JP7664787B2 - Carrier core material - Google Patents
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- JP7664787B2 JP7664787B2 JP2021125260A JP2021125260A JP7664787B2 JP 7664787 B2 JP7664787 B2 JP 7664787B2 JP 2021125260 A JP2021125260 A JP 2021125260A JP 2021125260 A JP2021125260 A JP 2021125260A JP 7664787 B2 JP7664787 B2 JP 7664787B2
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- 239000011162 core material Substances 0.000 title claims description 129
- 239000002245 particle Substances 0.000 claims description 170
- 229910000859 α-Fe Inorganic materials 0.000 claims description 63
- 238000011161 development Methods 0.000 claims description 42
- 239000000203 mixture Substances 0.000 claims description 32
- 229920005989 resin Polymers 0.000 claims description 27
- 239000011347 resin Substances 0.000 claims description 27
- 230000005415 magnetization Effects 0.000 claims description 21
- 229910052758 niobium Inorganic materials 0.000 claims description 13
- 229910052791 calcium Inorganic materials 0.000 claims description 11
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims description 11
- 239000011148 porous material Substances 0.000 claims description 11
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 4
- 229910052753 mercury Inorganic materials 0.000 claims description 4
- 238000002459 porosimetry Methods 0.000 claims description 2
- 238000000034 method Methods 0.000 description 42
- 239000011575 calcium Substances 0.000 description 30
- 239000010955 niobium Substances 0.000 description 30
- 239000002994 raw material Substances 0.000 description 30
- 238000005259 measurement Methods 0.000 description 19
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 17
- 239000000843 powder Substances 0.000 description 17
- 239000008187 granular material Substances 0.000 description 16
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 15
- 238000004458 analytical method Methods 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- 238000005245 sintering Methods 0.000 description 13
- 239000000243 solution Substances 0.000 description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 239000002270 dispersing agent Substances 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- 239000011777 magnesium Substances 0.000 description 10
- 238000010438 heat treatment Methods 0.000 description 9
- 239000002002 slurry Substances 0.000 description 9
- 238000010304 firing Methods 0.000 description 8
- 239000000395 magnesium oxide Substances 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 239000012298 atmosphere Substances 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- 239000011268 mixed slurry Substances 0.000 description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 6
- 150000001875 compounds Chemical class 0.000 description 6
- ZKATWMILCYLAPD-UHFFFAOYSA-N niobium pentoxide Chemical compound O=[Nb](=O)O[Nb](=O)=O ZKATWMILCYLAPD-UHFFFAOYSA-N 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 5
- 239000006229 carbon black Substances 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- 238000011156 evaluation Methods 0.000 description 5
- 229920005646 polycarboxylate Polymers 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- 239000007921 spray Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- 239000011230 binding agent Substances 0.000 description 4
- 239000002612 dispersion medium Substances 0.000 description 4
- AMWRITDGCCNYAT-UHFFFAOYSA-L manganese oxide Inorganic materials [Mn].O[Mn]=O.O[Mn]=O AMWRITDGCCNYAT-UHFFFAOYSA-L 0.000 description 4
- VASIZKWUTCETSD-UHFFFAOYSA-N manganese(II) oxide Inorganic materials [Mn]=O VASIZKWUTCETSD-UHFFFAOYSA-N 0.000 description 4
- 238000005086 pumping Methods 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000001694 spray drying Methods 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 3
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 3
- 239000002390 adhesive tape Substances 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 229910052742 iron Inorganic materials 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000003801 milling Methods 0.000 description 3
- 238000003918 potentiometric titration Methods 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- 229910052712 strontium Inorganic materials 0.000 description 3
- ZNQVEEAIQZEUHB-UHFFFAOYSA-N 2-ethoxyethanol Chemical compound CCOCCO ZNQVEEAIQZEUHB-UHFFFAOYSA-N 0.000 description 2
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910000616 Ferromanganese Inorganic materials 0.000 description 2
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- XECAHXYUAAWDEL-UHFFFAOYSA-N acrylonitrile butadiene styrene Chemical compound C=CC=C.C=CC#N.C=CC1=CC=CC=C1 XECAHXYUAAWDEL-UHFFFAOYSA-N 0.000 description 2
- 239000004676 acrylonitrile butadiene styrene Substances 0.000 description 2
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 235000011114 ammonium hydroxide Nutrition 0.000 description 2
- 238000009530 blood pressure measurement Methods 0.000 description 2
- 235000010216 calcium carbonate Nutrition 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000012937 correction Methods 0.000 description 2
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002149 energy-dispersive X-ray emission spectroscopy Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000006870 function Effects 0.000 description 2
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 239000006249 magnetic particle Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000003607 modifier Substances 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- -1 polyethylene Polymers 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 229920000915 polyvinyl chloride Polymers 0.000 description 2
- 239000004800 polyvinyl chloride Substances 0.000 description 2
- 238000010298 pulverizing process Methods 0.000 description 2
- 238000004445 quantitative analysis Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 229910000018 strontium carbonate Inorganic materials 0.000 description 2
- LEDMRZGFZIAGGB-UHFFFAOYSA-L strontium carbonate Chemical compound [Sr+2].[O-]C([O-])=O LEDMRZGFZIAGGB-UHFFFAOYSA-L 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- POAOYUHQDCAZBD-UHFFFAOYSA-N 2-butoxyethanol Chemical compound CCCCOCCO POAOYUHQDCAZBD-UHFFFAOYSA-N 0.000 description 1
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 238000012935 Averaging Methods 0.000 description 1
- 229910001369 Brass Inorganic materials 0.000 description 1
- DKPFZGUDAPQIHT-UHFFFAOYSA-N Butyl acetate Natural products CCCCOC(C)=O DKPFZGUDAPQIHT-UHFFFAOYSA-N 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- 229910000669 Chrome steel Inorganic materials 0.000 description 1
- 229910017135 Fe—O Inorganic materials 0.000 description 1
- NTIZESTWPVYFNL-UHFFFAOYSA-N Methyl isobutyl ketone Chemical compound CC(C)CC(C)=O NTIZESTWPVYFNL-UHFFFAOYSA-N 0.000 description 1
- UIHCLUNTQKBZGK-UHFFFAOYSA-N Methyl isobutyl ketone Natural products CCC(C)C(C)=O UIHCLUNTQKBZGK-UHFFFAOYSA-N 0.000 description 1
- 229910019440 Mg(OH) Inorganic materials 0.000 description 1
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 1
- 229910019714 Nb2O3 Inorganic materials 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000005062 Polybutadiene Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000004793 Polystyrene Substances 0.000 description 1
- 229920001328 Polyvinylidene chloride Polymers 0.000 description 1
- 229910002402 SrFe12O19 Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000005456 alcohol based solvent Substances 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 150000004292 cyclic ethers Chemical class 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003759 ester based solvent Substances 0.000 description 1
- 239000004210 ether based solvent Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- FUZZWVXGSFPDMH-UHFFFAOYSA-N hexanoic acid Chemical compound CCCCCC(O)=O FUZZWVXGSFPDMH-UHFFFAOYSA-N 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 239000005453 ketone based solvent Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 235000014380 magnesium carbonate Nutrition 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 239000006148 magnetic separator Substances 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 239000011656 manganese carbonate Substances 0.000 description 1
- 235000006748 manganese carbonate Nutrition 0.000 description 1
- 229910000016 manganese(II) carbonate Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000007909 melt granulation Methods 0.000 description 1
- PHQOGHDTIVQXHL-UHFFFAOYSA-N n'-(3-trimethoxysilylpropyl)ethane-1,2-diamine Chemical compound CO[Si](OC)(OC)CCCNCCN PHQOGHDTIVQXHL-UHFFFAOYSA-N 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- HFLAMWCKUFHSAZ-UHFFFAOYSA-N niobium dioxide Inorganic materials O=[Nb]=O HFLAMWCKUFHSAZ-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- FWFGVMYFCODZRD-UHFFFAOYSA-N oxidanium;hydrogen sulfate Chemical compound O.OS(O)(=O)=O FWFGVMYFCODZRD-UHFFFAOYSA-N 0.000 description 1
- 239000003002 pH adjusting agent Substances 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920002857 polybutadiene Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 239000005033 polyvinylidene chloride Substances 0.000 description 1
- 239000012286 potassium permanganate Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000010334 sieve classification Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 238000010671 solid-state reaction Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
- 229920002725 thermoplastic elastomer Polymers 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 239000012856 weighed raw material Substances 0.000 description 1
- 238000001238 wet grinding Methods 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Landscapes
- Developing Agents For Electrophotography (AREA)
- Compounds Of Iron (AREA)
- Hard Magnetic Materials (AREA)
- Soft Magnetic Materials (AREA)
Description
本発明は、キャリア芯材並びにこれを用いた電子写真現像用キャリア及び電子写真用現像剤に関するものである。 The present invention relates to a carrier core material and a carrier for electrophotographic development and a developer for electrophotography that use the carrier core material.
例えば、電子写真方式を用いたファクシミリやプリンター、複写機などの画像形成装置では、感光体の表面に形成された静電潜像にトナーを付着させて可視像化し、この可視像を用紙等に転写した後、加熱・加圧して定着させている。高画質化やカラー化の観点から、現像剤としては、キャリアとトナーとを含むいわゆる二成分現像剤が広く使用されている。 For example, in electrophotographic image forming devices such as facsimiles, printers, and copiers, toner is applied to an electrostatic latent image formed on the surface of a photoconductor to make it visible, and this visible image is then transferred to paper or the like and fixed by applying heat and pressure. From the perspective of achieving high image quality and colorization, so-called two-component developers, which contain a carrier and toner, are widely used as developers.
二成分現像剤を用いた現像方式では、キャリアとトナーとを現像装置内で撹拌混合し、摩擦によってトナーを所定量まで帯電させる。そして、回転する現像ローラに現像剤を供給し、現像ローラ上で磁気ブラシを形成させて、磁気ブラシを介して感光体へトナーを電気的に移動させて感光体上の静電潜像を可視像化する。トナー移動後のキャリアは現像ローラ上から剥離されて現像装置内で再びトナーと混合される。このため、キャリアの特性として、磁気ブラシを形成する磁気特性と、所望の電荷をトナーに付与する帯電特性および繰り返し使用における耐久性が要求される。 In a development method using a two-component developer, the carrier and toner are mixed and stirred in a development device, and the toner is charged to a specified amount by friction. The developer is then supplied to a rotating development roller, a magnetic brush is formed on the development roller, and the toner is electrically transferred to the photoconductor via the magnetic brush, making the electrostatic latent image on the photoconductor visible. After the toner has been transferred, the carrier is peeled off from the development roller and mixed with the toner again in the development device. For this reason, the carrier's characteristics require magnetic properties that form a magnetic brush, charging properties that impart the desired charge to the toner, and durability for repeated use.
このようなキャリアとして、マグネタイトや各種フェライト等の磁性粒子（キャリア芯材）の表面を樹脂で被覆したものが一般に用いられている。ところが、キャリア芯材の表面を樹脂で被覆した樹脂被覆キャリアをトナーと混合して二成分現像剤とした場合、現像ローラの１周前の画像の影響を受けて画像濃度が低下する「現像メモリ」と呼ばれる不具合が生じることがあった。 Such carriers are generally made of magnetic particles (carrier core material) such as magnetite or various ferrites, the surface of which is coated with resin. However, when a resin-coated carrier, in which the surface of a carrier core material is coated with resin, is mixed with toner to form a two-component developer, a problem called "development memory" can occur, in which the image density decreases due to the influence of the image from the previous rotation of the developing roller.
この現像メモリは樹脂被覆キャリアの電気抵抗が高いことに起因するものと推測され、その対策の一つとして、例えば、特許文献１では、キャリア芯材の形状を特定形状として、樹脂被覆したキャリアの表面からキャリア芯材を所定割合で露出させて現像メモリを抑制する技術が提案されている。また特許文献２には、Ｓｒ（ストロンチウム）を含有させて、キャリア芯材の粒子の表面に微小な凹凸を形成する技術が提案されている。 This development memory is believed to be due to the high electrical resistance of the resin-coated carrier, and as one of the countermeasures, for example, Patent Document 1 proposes a technology in which the shape of the carrier core material is specified and a specified proportion of the carrier core material is exposed from the surface of the resin-coated carrier to suppress the development memory. Also, Patent Document 2 proposes a technology in which Sr (strontium) is incorporated to form minute irregularities on the surface of the carrier core material particles.
しかしながら、キャリア芯材にＳｒに添加すると、組成ＳｒＦｅ１２Ｏ１９の酸化物が析出する。当該酸化物は高い残留磁化と高い保磁力を有するため、キャリアの流動性が低下し、また現像ローラからのキャリアの離脱不良が発生することがある。そして、このようなキャリアの流動性の低下や現像ローラからの離脱不良に起因して画像に濃度ムラが表れることがあった。 However, when Sr is added to the carrier core material, an oxide having the composition SrFe12O19 is precipitated. Since the oxide has high remanence and high coercive force, the fluidity of the carrier is reduced and the carrier may not be properly separated from the developing roller. Such a reduction in the fluidity of the carrier and the carrier may not be properly separated from the developing roller may cause density unevenness in the image.
そこで、本発明の目的は現像メモリが抑制でき、しかも画像の濃度ムラも抑制できるキャリア芯材を提供することにある。 The object of the present invention is to provide a carrier core material that can suppress development memory and also suppress uneven density in images.
また本発明の他の目的は、長期間の使用においても安定して良好な画質画像を形成することができる電子写真現像用キャリア及び電子写真用現像剤を提供することにある。 Another object of the present invention is to provide a carrier for electrophotography and a developer for electrophotography that can stably form images of good quality even after long-term use.
前記目的を達成する本発明に係るキャリア芯材は、組成式（ＭｎＯ）ｘ（ＭｇＯ）ｙ（Ｆｅ２Ｏ３）ｚ（但し、ｘ：３０ｍｏｌ％以上５５ｍｏｌ％以下，ｙ：０ｍｏｌ％より大きく２０ｍｏｌ％以下，ｚ：４０ｍｏｌ％以上６０ｍｏｌ％以下，ｘ＋ｙ＋ｚ＝１００ｍｏｌ％）で表されるフェライト粒子から構成されるキャリア芯材であって、Ｃａが０．１ｍｏｌ％以上１．５ｍｏｌ％以下の範囲、Ｎｂが０．１ｍｏｌ％以上１．５ｍｏｌ％以下の範囲含有されていることを特徴とする。 The carrier core material according to the present invention, which achieves the above-mentioned object, is a carrier core material composed of ferrite particles represented by the composition formula (MnO) x (MgO) y ( Fe2O3 ) z (wherein x is 30 mol% or more and 55 mol% or less, y is greater than 0 mol % and 20 mol% or less, z is 40 mol% or more and 60 mol% or less, and x+y+z=100 mol%), and is characterized in that it contains Ca in the range of 0.1 mol% or more and 1.5 mol% or less and Nb in the range of 0.1 mol% or more and 1.5 mol% or less.
なお、本明細書においてＣａ及びＮｂの含有量は後述する実施例に記載の方法で測定した値である。また、本明細書において「フェライト粒子」、「キャリア芯材」、「電子写真現像用キャリア」、「電子写真用現像剤」は、それぞれ個々の粒子の集合体（粉体）を意味するものである。 In this specification, the Ca and Nb contents are values measured by the method described in the Examples below. In addition, in this specification, "ferrite particles," "carrier core material," "electrophotographic development carrier," and "electrophotographic developer" each mean an aggregate (powders) of individual particles.
前記構成のキャリア芯材において、ＣａとＮｂのｍｏｌ％での含有比Ｃａ／Ｎｂが１．０以上であるのが好ましい。 In the carrier core material having the above-mentioned configuration, it is preferable that the Ca/Nb content ratio in mol% of Ca and Nb is 1.0 or more.
前記構成のキャリア芯材において、前記フェライト粒子の表面の最大山谷深さＲｚは１．７μｍ以上２．５μｍ以下であるのが好ましい。 In the carrier core material having the above configuration, it is preferable that the maximum peak-valley depth Rz of the surface of the ferrite particles is 1.7 μm or more and 2.5 μm or less.
また前記構成のキャリア芯材において、前記フェライト粒子の残留磁化σｒは１．０（Ａ・ｍ２／ｋｇ）以下であるのが好ましい。 In the carrier core material having the above-mentioned configuration, the residual magnetization σr of the ferrite particles is preferably 1.0 (A·m 2 /kg) or less.
また前記構成のキャリア芯材において、前記フェライト粒子の保磁力Ｈｃは１０（Ａ／ｍ×１０３／（４π））以下であるのが好ましい。 In the carrier core material having the above-mentioned configuration, the coercive force Hc of the ferrite particles is preferably 10 (A/m×10 3 /(4π)) or less.
また前記構成のキャリア芯材において、水銀圧入法で測定される前記フェライト粒子の細孔容積が０．００３ｃｍ３／ｇ以上０．０２ｃｍ３／ｇ以下であるのが好ましい。 In the carrier core material having the above-mentioned configuration, the ferrite particles preferably have a pore volume of 0.003 cm 3 /g or more and 0.02 cm 3 /g or less as measured by mercury intrusion porosimetry.
また前記構成のキャリア芯材において、磁場７９．５８×１０３Ａ／ｍ（１０００エルステッド）を印加した際の前記フェライト粒子の磁化σ１ｋが４５Ａｍ２／ｋｇ以上７５Ａｍ２／ｋｇ以下であるのが好ましい。 In the carrier core material having the above-mentioned configuration, the magnetization σ 1k of the ferrite particles when a magnetic field of 79.58×10 3 A/m (1000 Oersted) is applied is preferably 45 Am 2 /kg or more and 75 Am 2 /kg or less.
また前記構成のキャリア芯材において、前記フェライト粒子の体積平均粒子径（以下、「平均粒子径」と記すことがある。）Ｄ５０が２０μｍ以上７５μｍ以下であるのが好ましい。 In the carrier core material having the above-mentioned configuration, the volume average particle diameter (hereinafter, sometimes referred to as "average particle diameter") D50 of the ferrite particles is preferably 20 μm or more and 75 μm or less.
また本発明によれば、前記のいずれかに記載のキャリア芯材の表面が樹脂で被覆されていることを特徴とする電子写真現像用キャリアが提供される。 The present invention also provides a carrier for electrophotographic development, characterized in that the surface of the carrier core material described above is coated with a resin.
そしてまた本発明によれば、前記記載の電子写真現像用キャリアとトナーとを含むことを特徴とする電子写真用現像剤が提供される。 The present invention also provides an electrophotographic developer that contains the electrophotographic development carrier and toner described above.
なお、「最大山谷深さＲｚ」、「残留磁化σｒ」、「保磁力Ｈｃ」、「細孔容積」、「磁化σ１ｋ」、「体積平均粒子径Ｄ５０」は後述する実施例に記載の方法で測定した値である。 The "maximum peak-valley depth Rz", "residual magnetization σ r ", "coercive force H c " , "pore volume", "magnetization σ 1k ", and "volume average particle diameter D 50 " are values measured by the method described in the examples below.
本発明に係るキャリア芯材によれば現像メモリが抑制できると共に画像の濃度ムラも抑制できる。 The carrier core material of the present invention can suppress development memory and also suppress uneven density of images.
また本発明に係るキャリア芯材を含む現像剤を用いれば、長期間の使用においても安定して良好な画質画像を形成することができる。 In addition, by using a developer containing the carrier core material of the present invention, it is possible to stably form images of good quality even after long-term use.
本発明者は現像メモリと濃度ムラの抑制が可能なキャリア芯材を得るため鋭意検討を重ねた結果、所定組成のフェライト粒子から構成されるキャリア芯材において、所定量のＣａ（カルシウム）とＮｂ（ニオブ）とを含有させることによって、キャリアの流動性の低下や現像ローラからの離脱不良を招くことなく、キャリア芯材の表面を凹凸化させて現像メモリを抑制できることを見出し本発明をなすに至った。 The inventors conducted extensive research to obtain a carrier core material capable of suppressing development memory and uneven density. As a result, they discovered that by incorporating a specified amount of Ca (calcium) and Nb (niobium) in a carrier core material composed of ferrite particles of a specified composition, it is possible to suppress development memory by making the surface of the carrier core material uneven without reducing the fluidity of the carrier or causing problems in releasing it from the developing roller, which led to the invention.
すなわち本発明に係るキャリア芯材の大きな特徴の一つは、Ｃａが０．１ｍｏｌ％以上１．５ｍｏｌ％以下の範囲、Ｎｂが０．１ｍｏｌ％以上１．５ｍｏｌ％以下の範囲含有されていることである。 That is, one of the major features of the carrier core material according to the present invention is that it contains Ca in the range of 0.1 mol% to 1.5 mol% and Nb in the range of 0.1 mol% to 1.5 mol%.
キャリア芯材にＣａを単独で含有させるとＣａ－Ｆｅ－Ｏ化合物の結晶相が生成しキャリア芯材の表面凹凸化はある程度は図れるものの現像メモリの十分な発生抑制には至らない。一方、キャリア芯材にＣａと共にＮｂを含有させると、焼成時にＣａ－Ｎｂ－Ｏ化合物の結晶相が優先的に生成されてフェライト粒子の結晶粒界に留まってフェライト粒子の結晶の面内方向の成長が抑制されてフェライト粒子の表面凹凸化が促進される。加えて、Ｃａ－Ｎｂ－Ｏ化合物は、従来使用されていたＳｒとＦｅの酸化物に比べてキャリア芯材の残留磁化及び保磁力の上昇は招きにくい。 When Ca is added alone to the carrier core material, a crystalline phase of Ca-Fe-O compound is generated, which can create some surface irregularities in the carrier core material, but does not sufficiently suppress the occurrence of development memory. On the other hand, when Nb is added together with Ca to the carrier core material, a crystalline phase of Ca-Nb-O compound is preferentially generated during firing and remains at the grain boundaries of the ferrite particles, suppressing the in-plane growth of the ferrite particle crystals and promoting the creation of surface irregularities in the ferrite particles. In addition, the Ca-Nb-O compound is less likely to cause an increase in the residual magnetization and coercive force of the carrier core material than the oxides of Sr and Fe that were previously used.
なお、キャリア芯材の原料成分としてＣａとＮｂとを配合すると焼成時にＣａ－Ｎｂ－Ｏ化合物の結晶相が生成されることは、作製したキャリア芯材の走査型電子顕微鏡（ＳＥＭ：Scanning Electron Microscope）によるエネルギー分散型Ｘ線分析（ＥＤＳ：Energy dispersive X-ray spectroscopy）からも確認されている。図１にキャリア芯材のＳＥＭ－ＥＤＳ写真の一例を示す。同図（ａ）はキャリア芯材のＳＥＭ写真、同図（ｂ）は同図（ａ）の部分拡大写真、同図（ｃ）は同図（ｂ）の視野におけるＣａ元素の存在領域を示す写真、同図（ｄ）は同図（ｂ）の視野におけるＮｂ元素の存在領域を示す写真である。図１（ｃ）と図１（ｄ）を見比べれば明らかなように、Ｃａ元素とＮｂ元素とはほぼ同じ領域に存在しており、キャリア芯材中にＣａ－Ｎｂ－Ｏ化合物の結晶相が生成されていることがわかる。 It has also been confirmed by energy dispersive X-ray spectroscopy (EDS) of the carrier core material produced by a scanning electron microscope (SEM) that a crystal phase of the Ca-Nb-O compound is generated during firing when Ca and Nb are mixed as raw material components of the carrier core material. Figure 1 shows an example of an SEM-EDS photograph of the carrier core material. Figure 1(a) is an SEM photograph of the carrier core material, Figure 1(b) is a partially enlarged photograph of Figure 1(a), Figure 1(c) is a photograph showing the presence area of Ca element in the field of view of Figure 1(b), and Figure 1(d) is a photograph showing the presence area of Nb element in the field of view of Figure 1(b). As is clear from a comparison of Figure 1(c) and Figure 1(d), the Ca element and the Nb element are present in almost the same region, and it can be seen that a crystal phase of the Ca-Nb-O compound is generated in the carrier core material.
Ｃａ及びＮｂの各々の含有割合はいずれも０．１ｍｏｌ％以上１．５ｍｏｌ％以下の範囲である。Ｃａ及びＮｂの含有割合が０．１ｍｏｌ％未満であると本発明の所期の効果が得られない。一方、Ｃａ及びＮｂの含有割合が１．５ｍｏｌ％を超えるとキャリア芯材の保磁力Ｈｃの上昇を招き濃度ムラが発生するおそれがある。 The respective contents of Ca and Nb are in the range of 0.1 mol% to 1.5 mol%. If the Ca and Nb contents are less than 0.1 mol%, the desired effect of the present invention cannot be obtained. On the other hand, if the Ca and Nb contents exceed 1.5 mol%, the coercive force Hc of the carrier core material increases, which may cause concentration unevenness.
またＣａとＮｂのｍｏｌ％での含有比Ｃａ／Ｎｂは１．０以上であるのが好ましい。含有比Ｃａ／Ｎｂが１．０未満であると、すなわちＮｂの含有量がＣａの含有量よりも多いとＣａ－Ｎｂ－Ｏ化合物の生成に寄与しないＮｂが存在することとなり、理由は未だ明確には成っていないが、フェライト相の一部が分解してヘマタイト相が形成され現像メモリが発生するするおそれがある。含有比Ｃａ／Ｎｂの好ましい上限値は１０．０であり、より好ましい上限値は５．０である。 The Ca/Nb content ratio in mol% of Ca and Nb is preferably 1.0 or more. If the Ca/Nb content ratio is less than 1.0, that is, if the Nb content is greater than the Ca content, there will be Nb that does not contribute to the formation of Ca-Nb-O compounds, and although the reason is not yet clear, there is a risk that part of the ferrite phase will decompose to form a hematite phase, resulting in development memory. The preferred upper limit of the Ca/Nb content ratio is 10.0, and the more preferred upper limit is 5.0.
本発明のキャリア芯材を構成するフェライト粒子は、組成式（ＭｎＯ）ｘ（ＭｇＯ）ｙ（Ｆｅ２Ｏ３）ｚ（但し、ｘ：３０ｍｏｌ％以上５５ｍｏｌ％以下，ｙ：２０ｍｏｌ％以下，ｚ：４０ｍｏｌ％以上６０ｍｏｌ％以下，ｘ＋ｙ＋ｚ＝１００ｍｏｌ％）の組成を有する。上記ｘが５５ｍｏｌ％超及び上記ｙが２０ｍｏｌ％超では、キャリア芯材の磁化が低すぎて実使用においてはキャリア付着などの不具合が発生するおそれがある。またｘが３０ｍｏｌ％未満では、キャリア芯材の磁化が高くなるため画像ムラが発生するおそれがある。 The ferrite particles constituting the carrier core material of the present invention have a composition represented by the formula (MnO) x (MgO) y ( Fe2O3 ) z (wherein x is 30 mol% or more and 55 mol% or less, y is 20 mol% or less, z is 40 mol% or more and 60 mol% or less, and x+y+z=100 mol%). If x is more than 55 mol% and y is more than 20 mol%, the magnetization of the carrier core material is too low, and problems such as carrier adhesion may occur in practical use. If x is less than 30 mol%, the magnetization of the carrier core material is too high, and image unevenness may occur.
本発明のキャリア芯材を構成するフェライト粒子の表面の最大山谷深さＲｚは１．７μｍ以上２．５μｍ以下の範囲が好ましい。フェライト粒子の表面の最大山谷深さＲｚが１．７μｍ未満であると、キャリア芯材表面が樹脂被覆されて樹脂被覆キャリアとされた際に樹脂被覆キャリアの表面にキャリア芯材が十分に露出することができず、樹脂被覆キャリアに溜まったカウンタチャージが円滑に外部に放出されずに現像メモリが発生するおそれがある。一方、フェライト粒子の表面の最大山谷深さＲｚが２．５μｍを超えると、樹脂被覆キャリアの流動性が低下し濃度ムラが発生するおそれがある。最大山谷深さＲｚのより好ましい範囲は１．７μｍ以上２．２μｍ以下の範囲である。フェライト粒子の表面の最大山谷深さＲｚの制御は、原料におけるＣａ及びＮｂの添加量及び製造工程における焼成条件などによって行うことができる。 The maximum peak-valley depth Rz of the surface of the ferrite particles constituting the carrier core material of the present invention is preferably in the range of 1.7 μm to 2.5 μm. If the maximum peak-valley depth Rz of the surface of the ferrite particles is less than 1.7 μm, when the surface of the carrier core material is resin-coated to form a resin-coated carrier, the carrier core material cannot be sufficiently exposed on the surface of the resin-coated carrier, and the counter charge accumulated in the resin-coated carrier cannot be smoothly released to the outside, which may cause development memory. On the other hand, if the maximum peak-valley depth Rz of the surface of the ferrite particles exceeds 2.5 μm, the fluidity of the resin-coated carrier may decrease and density unevenness may occur. A more preferable range of the maximum peak-valley depth Rz is 1.7 μm to 2.2 μm. The maximum peak-valley depth Rz of the surface of the ferrite particles can be controlled by the amount of Ca and Nb added to the raw material and the firing conditions in the manufacturing process.
本発明のキャリア芯材を構成するフェライト粒子の残留磁化σｒは１．０（Ａ・ｍ２／ｋｇ）以下であるのが好ましい。フェライト粒子の残留磁化σｒが１．０（Ａ・ｍ２／ｋｇ）を超えると、現像ローラからのキャリアの離脱不良が発生し画像に濃度ムラが表れるおそれがある。フェライト粒子の残留磁化σｒのより好ましい上限値は０．８（Ａ・ｍ２／ｋｇ）である。また残留磁化σｒの好ましい下限値は０．５（Ａ・ｍ２／ｋｇ）である。 The residual magnetization σr of the ferrite particles constituting the carrier core material of the present invention is preferably 1.0 (A· m2 /kg) or less. If the residual magnetization σr of the ferrite particles exceeds 1.0 (A· m2 /kg), there is a risk that the carrier may not be properly separated from the developing roller, resulting in uneven density in the image. A more preferable upper limit of the residual magnetization σr of the ferrite particles is 0.8 (A· m2 /kg). Also, a preferable lower limit of the residual magnetization σr is 0.5 (A· m2 /kg).
本発明のキャリア芯材を構成するフェライト粒子の保磁力Ｈｃは１０（Ａ／ｍ×１０３／（４π））以下であるのが好ましい。フェライト粒子の保磁力Ｈｃが１０（Ａ／ｍ×１０３／（４π））を超えると、現像ローラからのキャリアの離脱不良が発生し画像に濃度ムラが表れるおそれがある。フェライト粒子の保磁力Ｈｃのより好ましい上限値は９．５（Ａ／ｍ×１０３／（４π））である。また保磁力Ｈｃの好ましい下限値は５．０（Ａ／ｍ×１０３／（４π））である。 The coercive force Hc of the ferrite particles constituting the carrier core material of the present invention is preferably 10 (A/m×10 3 /(4π)) or less. If the coercive force Hc of the ferrite particles exceeds 10 (A/m×10 3 /(4π)), poor separation of the carrier from the developing roller may occur, resulting in uneven density in the image. A more preferred upper limit of the coercive force Hc of the ferrite particles is 9.5 (A/m×10 3 /(4π)). A preferred lower limit of the coercive force Hc is 5.0 (A/m×10 3 /(4π)).
本発明のキャリア芯材を構成するフェライト粒子の細孔容積は０．００３ｃｍ３／ｇ以上０．０２ｃｍ３／ｇ以下の範囲が好ましい。フェライト粒子の細孔容積が０．００３ｃｍ３／ｇ未満であると、キャリア芯材一粒子あたりの磁化が大きくなり過ぎて現像ローラからのキャリアの離脱不良が発生し画像に濃度ムラが表れるおそれがある。一方、フェライト粒子の細孔容積が０．０２ｃｍ３／ｇを超えると内部空隙が大きくなり過ぎてキャリア芯材一粒子あたりの磁化が小さくなり過ぎキャリア飛散が生じやすくなる。フェライト粒子の細孔容積のより好ましい範囲は０．００４ｃｍ３／ｇ以上０．０１５ｃｍ３／ｇ以下の範囲である。 The pore volume of the ferrite particles constituting the carrier core material of the present invention is preferably in the range of 0.003 cm 3 /g or more and 0.02 cm 3 /g or less. If the pore volume of the ferrite particles is less than 0.003 cm 3 /g, the magnetization per particle of the carrier core material becomes too large, which may cause the carrier to be poorly separated from the developing roller, resulting in uneven density in the image. On the other hand, if the pore volume of the ferrite particles exceeds 0.02 cm 3 /g, the internal void becomes too large, which causes the magnetization per particle of the carrier core material to become too small, which may cause carrier scattering. The pore volume of the ferrite particles is more preferably in the range of 0.004 cm 3 /g or more and 0.015 cm 3 /g or less.
本発明のキャリア芯材を構成するフェライト粒子の磁化σ１ｋは４５Ａｍ２／ｋｇ以上７５Ａｍ２／ｋｇ以下であるのが好ましい。フェライト粒子の磁化σ１ｋが４５Ａｍ２／ｋｇ未満であると磁力が小さくなりすぎてキャリア飛散が発生するおそれがある。一方、フェライト粒子の磁化σ１ｋが７５Ａｍ２／ｋｇを超えると磁力が大きくなりすぎて現像ローラからのキャリアの離脱不良が発生し画像に濃度ムラが表れるおそれがある。 The magnetization σ 1k of the ferrite particles constituting the carrier core material of the present invention is preferably 45 Am 2 /kg or more and 75 Am 2 /kg or less. If the magnetization σ 1k of the ferrite particles is less than 45 Am 2 /kg, the magnetic force may be too small, causing carrier scattering. On the other hand, if the magnetization σ 1k of the ferrite particles exceeds 75 Am 2 /kg, the magnetic force may be too large, causing poor separation of the carrier from the developing roller, causing density unevenness in the image.
本発明のキャリア芯材を構成するフェライト粒子の平均粒子径Ｄ５０は２０μｍ以上７５μｍ以下の範囲が好ましく、より好ましくは３０μｍ以上４０μｍ以下の範囲である。またフェライト粒子の粒度分布はシャープであるのが好ましい。 The average particle diameter D50 of the ferrite particles constituting the carrier core material of the present invention is preferably in the range of 20 μm to 75 μm, more preferably in the range of 30 μm to 40 μm. The particle size distribution of the ferrite particles is preferably sharp.
本発明のキャリア芯材を構成するフェライト粒子の製造方法に特に限定はないが、以下に説明する製造方法が好適である。 There are no particular limitations on the method for producing the ferrite particles that make up the carrier core material of the present invention, but the manufacturing method described below is preferred.
まず、Ｆｅ成分原料、Ｍｎ成分原料、Ｍｇ成分原料、Ｃａ成分原料、Ｎｂ成分原料、そして必要により添加剤を秤量する。Ｆｅ成分原料としては、Ｆｅ２Ｏ３等が好適に使用される。Ｍｎ成分原料としてはＭｎＣＯ３、Ｍｎ３Ｏ４等が使用でき、Ｍｇ成分原料であればＭｇＯ、Ｍｇ（ＯＨ）２、ＭｇＣＯ３、ＭｇＦｅ２Ｏ４が使用でき、Ｃａ成分原料としては、ＣａＯ、Ｃａ（ＯＨ）２、ＣａＣＯ３等が使用でき、Ｎｂ成分原料としては、Ｎｂ２Ｏ５、ＮｂＯ２、Ｎｂ２Ｏ３等が使用できる。 First, Fe component raw material, Mn component raw material, Mg component raw material, Ca component raw material, Nb component raw material, and additives are weighed out as necessary. As the Fe component raw material, Fe2O3 and the like are preferably used. As the Mn component raw material, MnCO3 , Mn3O4 , and the like can be used, as the Mg component raw material, MgO, Mg(OH) 2 , MgCO3 , MgFe2O4 can be used, as the Ca component raw material, CaO, Ca(OH) 2 , CaCO3, and the like can be used, and as the Nb component raw material, Nb2O5 , NbO2 , Nb2O3 , and the like can be used.
次いで、原料を狙いとするキャリア芯材組成と同じ質量比で分散媒中に投入しスラリーを作製する。本発明で使用する分散媒としては水が好適である。分散媒には、前記仮焼成原料の他、必要によりバインダー、分散剤等を配合してもよい。バインダーとしては、例えば、ポリビニルアルコールが好適に使用できる。バインダーの配合量としてはスラリー中の濃度が０．１質量％～２質量％程度とするのが好ましい。また、分散剤としては、例えば、ポリカルボン酸アンモニウム等が好適に使用できる。分散剤の配合量としてはスラリー中の濃度が０．１質量％～２質量％程度とするのが好ましい。その他、カーボンブラックなどの還元剤、アンモニアなどのｐＨ調整剤、潤滑剤、焼結促進剤等を配合してもよい。スラリーの固形分濃度は５０質量％～９０質量％の範囲が望ましい。より好ましくは６０質量％～８０質量％である。６０質量％以上であれば、造粒物中に粒子内細孔が少なく、焼成時の焼結不足を防ぐことができる。 Next, the raw materials are put into a dispersion medium in the same mass ratio as the target carrier core material composition to prepare a slurry. Water is a suitable dispersion medium for use in the present invention. In addition to the pre-sintered raw materials, a binder, a dispersant, etc. may be mixed into the dispersion medium as necessary. For example, polyvinyl alcohol is suitable for use as a binder. The amount of binder mixed is preferably about 0.1% by mass to 2% by mass in the slurry. For example, ammonium polycarboxylate is suitable for use as a dispersant. The amount of dispersant mixed is preferably about 0.1% by mass to 2% by mass in the slurry. In addition, a reducing agent such as carbon black, a pH adjuster such as ammonia, a lubricant, a sintering accelerator, etc. may be mixed. The solid content concentration of the slurry is preferably in the range of 50% by mass to 90% by mass. More preferably, it is 60% by mass to 80% by mass. If it is 60% by mass or more, there are few pores in the particles in the granulated material, and insufficient sintering during firing can be prevented.
なお、秤量した原料を混合し仮焼成し解粒した後、分散媒に投入しスラリーを作製してもよい。仮焼成の温度としては７５０℃～１０００℃の範囲が好ましい。７５０℃以上であれば、仮焼による一部フェライト化が進み、焼成時のガス発生量が少なく、固体間反応が十分に進むため、好ましい。一方、１０００℃以下であれば、仮焼による焼結が弱く、後のスラリー粉砕工程で原料を十分に粉砕できるので好ましい。また、仮焼成時の雰囲気としては大気雰囲気が好ましい。 The weighed raw materials may be mixed, pre-fired, and deagglomerated, and then poured into a dispersion medium to produce a slurry. The pre-fire temperature is preferably in the range of 750°C to 1000°C. A temperature of 750°C or higher is preferable because partial ferritization by pre-fire progresses, the amount of gas generated during firing is small, and solid-state reactions progress sufficiently. On the other hand, a temperature of 1000°C or lower is preferable because sintering by pre-fire is weak, and the raw materials can be sufficiently pulverized in the subsequent slurry pulverization process. Furthermore, air is preferable as the atmosphere during pre-fire.
次に、以上のようにして作製されたスラリーを湿式粉砕する。例えば、ボールミルや振動ミルを用いて所定時間湿式粉砕する。粉砕後の原材料の平均粒子径は５μｍ以下が好ましく、より好ましくは１μｍ以下である。振動ミルやボールミルには、所定粒径のメディアを内在させるのがよい。メディアの材質としては、鉄系のクロム鋼や酸化物系のジルコニア、チタニア、アルミナなどが挙げられる。粉砕工程の形態としては連続式及び回分式のいずれであってもよい。粉砕物の粒径は、粉砕時間や回転速度、使用するメディアの材質・粒径などによって調整される。 Next, the slurry prepared as described above is wet-milled. For example, wet-milling is performed for a predetermined time using a ball mill or a vibration mill. The average particle size of the raw material after milling is preferably 5 μm or less, more preferably 1 μm or less. It is preferable that the vibration mill or ball mill contains media of a predetermined particle size. Examples of media materials include iron-based chrome steel and oxide-based zirconia, titania, alumina, etc. The milling process may be either continuous or batch-based. The particle size of the milled product is adjusted by the milling time, rotation speed, material and particle size of the media used, etc.
そして、粉砕されたスラリーを噴霧乾燥させて造粒する。具体的には、スプレードライヤーなどの噴霧乾燥機にスラリーを導入し、雰囲気中へ噴霧することによって球形に造粒する。噴霧乾燥時の雰囲気温度は１００℃～３００℃の範囲が好ましい。これにより、粒径１０μｍ～２００μｍの球形の造粒物が得られる。次いで、必要により、得られた造粒物を振動篩を用いて分級し所定の粒径範囲の造粒物を作製する。 The pulverized slurry is then spray-dried to form granules. Specifically, the slurry is introduced into a spray dryer or other spray drying machine, and sprayed into the atmosphere to form spherical granules. The atmospheric temperature during spray drying is preferably in the range of 100°C to 300°C. This results in spherical granules with a particle size of 10 μm to 200 μm. Next, if necessary, the resulting granules are classified using a vibrating sieve to produce granules in a specified particle size range.
次に、前記の造粒物を所定温度に加熱した炉に投入して、フェライト粒子を合成するための一般的な手法で焼成することにより、フェライト粒子を生成させる。焼成温度としては１１００℃～１３５０℃の範囲が好ましい。焼成温度が１１００℃以下であると、相変態が起こりにくくなるとともに焼結も進みにくくなる。また、焼成温度が１３５０℃を超えると、過剰焼結による過大グレインの発生がするおそれがある。前記焼成温度に至るまでの昇温速度としては２５０℃／ｈ～５００℃／ｈの範囲が好ましい。焼成温度での保持時間は２時間以上が好ましい。フェライト粒子の表面の凹凸は焼成工程における酸素濃度によっても調整可能である。具体的には酸素濃度を５００ｐｐｍ～１０００００ｐｐｍとする。また、冷却時の酸素濃度を焼成時の酸素濃度よりも低くすることによって、フェライト相の酸化状態の調整を図ってもよい。具体的には酸素濃度を５００ｐｐｍ～３００００ｐｐｍの範囲とする。昇温・焼結・冷却における酸素濃度は５００ｐｐｍ～１０００００ｐｐｍの範囲に制御するのが好ましい。 Next, the granulated material is put into a furnace heated to a predetermined temperature and sintered by a general method for synthesizing ferrite particles to generate ferrite particles. The sintering temperature is preferably in the range of 1100°C to 1350°C. If the sintering temperature is 1100°C or lower, phase transformation is unlikely to occur and sintering is unlikely to proceed. If the sintering temperature exceeds 1350°C, excessive sintering may cause excessive grains to be generated. The heating rate up to the sintering temperature is preferably in the range of 250°C/h to 500°C/h. The holding time at the sintering temperature is preferably 2 hours or more. The unevenness of the surface of the ferrite particles can also be adjusted by the oxygen concentration in the sintering process. Specifically, the oxygen concentration is set to 500 ppm to 100,000 ppm. In addition, the oxidation state of the ferrite phase may be adjusted by setting the oxygen concentration during cooling lower than the oxygen concentration during sintering. Specifically, the oxygen concentration is set to the range of 500 ppm to 30,000 ppm. It is preferable to control the oxygen concentration during heating, sintering, and cooling to a range of 500 ppm to 100,000 ppm.
このようにして得られた焼成物を必要により解粒する。具体的には、例えば、ハンマーミル等によって焼成物を解粒する。解粒工程の形態としては連続式及び回分式のいずれであってもよい。また解粒処理後、必要により、粒径を所定範囲に揃えるため分級を行ってもよい。分級方法としては、風力分級や篩分級など従来公知の方法を用いることができる。また、風力分級機で１次分級した後、振動篩や超音波篩で粒径を所定範囲に揃えるようにしてもよい。さらに、分級工程後に、磁場選鉱機によって非磁性粒子を除去するようにしてもよい。フェライト粒子の平均粒子径としては２０μｍ以上７５μｍ以下の範囲が好ましい。 The sintered product thus obtained is disintegrated as necessary. Specifically, the sintered product is disintegrated, for example, by a hammer mill or the like. The disintegration process may be either continuous or batchwise. After the disintegration process, classification may be performed to adjust the particle size to a predetermined range, if necessary. As a classification method, a conventionally known method such as wind classification or sieve classification may be used. After primary classification using a wind classifier, the particle size may be adjusted to a predetermined range using a vibrating sieve or ultrasonic sieve. Furthermore, after the classification process, non-magnetic particles may be removed using a magnetic separator. The average particle size of the ferrite particles is preferably in the range of 20 μm to 75 μm.
その後、必要に応じて、分級後のフェライト粒子を酸化性雰囲気中で加熱して、粒子表面に酸化被膜を形成してフェライト粒子の高抵抗化を図ってもよい（高抵抗化処理）。酸化性雰囲気としては大気雰囲気又は酸素と窒素の混合雰囲気のいずれでもよい。また、加熱温度は２００℃以上８００℃以下の範囲が好ましく、３６０℃以上５５０℃以下の範囲がさらに好ましい。加熱時間は０．５時間以上５時間以下の範囲が好ましい。なお、フェライト粒子の表面と内部とを均質化する観点からは加熱温度は低温であるのが望ましい。 If necessary, the classified ferrite particles may then be heated in an oxidizing atmosphere to form an oxide film on the particle surface and increase the resistance of the ferrite particles (resistance-increasing treatment). The oxidizing atmosphere may be either an air atmosphere or a mixed atmosphere of oxygen and nitrogen. The heating temperature is preferably in the range of 200°C to 800°C, more preferably in the range of 360°C to 550°C. The heating time is preferably in the range of 0.5 hours to 5 hours. From the viewpoint of homogenizing the surface and interior of the ferrite particles, a low heating temperature is desirable.
以上のようにして作製したフェライト粒子を本発明のキャリア芯材として用いる。そして、所望の帯電性等を得るために、キャリア芯材の外周を樹脂で被覆して電子写真現像用キャリアとする。 The ferrite particles prepared as described above are used as the carrier core material of the present invention. Then, in order to obtain the desired charging properties, the outer periphery of the carrier core material is coated with resin to form a carrier for electrophotographic development.
キャリア芯材の表面を被覆する樹脂としては、従来公知のものが使用でき、例えば、ポリエチレン、ポリプロピレン、ポリ塩化ビニル、ポリ－４－メチルペンテン－１、ポリ塩化ビニリデン、ＡＢＳ（アクリロニトリル－ブタジエン－スチレン）樹脂、ポリスチレン、（メタ）アクリル系樹脂、ポリビニルアルコール系樹脂、並びにポリ塩化ビニル系やポリウレタン系、ポリエステル系、ポリアミド系、ポリブタジエン系等の熱可塑性エストラマー、フッ素シリコーン系樹脂などが挙げられる。 The resin that coats the surface of the carrier core material can be any of the conventionally known resins, such as polyethylene, polypropylene, polyvinyl chloride, poly-4-methylpentene-1, polyvinylidene chloride, ABS (acrylonitrile-butadiene-styrene) resin, polystyrene, (meth)acrylic resin, polyvinyl alcohol resin, as well as thermoplastic elastomers such as polyvinyl chloride, polyurethane, polyester, polyamide, and polybutadiene, and fluorosilicone resin.
キャリア芯材の表面を樹脂で被覆するには、樹脂の溶液又は分散液をキャリア芯材に施せばよい。塗布溶液用の溶媒としては、トルエン、キシレン等の芳香族炭化水素系溶媒；アセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノン等のケトン系溶媒；テトラヒドロフラン、ジオキサン等の環状エーテル類溶媒；エタノール、プロパノール、ブタノール等のアルコール系溶媒；エチルセロソルブ、ブチルセロソルブ等のセロソルブ系溶媒；酢酸エチル、酢酸ブチル等のエステル系溶媒；ジメチルホルムアミド、ジメチルアセトアミド等のアミド系溶媒などの１種又は２種以上を用いることができる。塗布溶液中の樹脂成分濃度は、一般に０．００１質量％以上３０質量％以下、特に０．００１質量％以上２質量％以下の範囲内にあるのがよい。 To coat the surface of the carrier core material with a resin, a solution or dispersion of the resin may be applied to the carrier core material. As the solvent for the coating solution, one or more of the following may be used: aromatic hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cyclic ether solvents such as tetrahydrofuran and dioxane; alcohol solvents such as ethanol, propanol, and butanol; cellosolve solvents such as ethyl cellosolve and butyl cellosolve; ester solvents such as ethyl acetate and butyl acetate; and amide solvents such as dimethylformamide and dimethylacetamide. The resin component concentration in the coating solution is generally in the range of 0.001% by mass to 30% by mass, and particularly 0.001% by mass to 2% by mass.
キャリア芯材への樹脂の被覆方法としては、例えばスプレードライ法や流動床法あるいは流動床を用いたスプレードライ法、浸漬法等を用いることができる。これらの中でも、少ない樹脂量で効率的に塗布できる点で流動床法が特に好ましい。樹脂被覆量は、例えば流動床法の場合には吹き付ける樹脂溶液量や吹き付け時間によって調整することができる。 Methods for coating the carrier core with resin include, for example, the spray-drying method, the fluidized bed method, the spray-drying method using a fluidized bed, and the immersion method. Among these, the fluidized bed method is particularly preferred because it allows efficient application with a small amount of resin. In the case of the fluidized bed method, for example, the amount of resin coating can be adjusted by the amount of resin solution sprayed and the spraying time.
キャリアの粒子径は、一般に、体積平均粒子径で２０μｍ以上７５μｍ以下の範囲、特に３０μｍ以上４０μｍ以下の範囲が好ましい。 The particle size of the carrier is generally in the range of 20 μm to 75 μm in volume average particle size, and preferably in the range of 30 μm to 40 μm.
本発明に係る電子写真用現像剤は、以上のようにして作製したキャリアとトナーとを混合してなる。キャリアとトナーとの混合比に特に限定はなく、使用する現像装置の現像条件などから適宜決定すればよい。一般に現像剤中のトナー濃度は１質量％以上１５質量％以下の範囲が好ましい。トナー濃度が１質量％未満の場合、画像濃度が薄くなりすぎ、他方トナー濃度が１５質量％を超える場合、現像装置内でトナー飛散が発生し機内汚れや転写紙などの背景部分にトナーが付着する不具合が生じるおそれがあるからである。より好ましいトナー濃度は３質量％以上１０質量％以下の範囲である。 The electrophotographic developer according to the present invention is made by mixing the carrier and toner prepared as described above. There is no particular limitation on the mixture ratio of the carrier and toner, and it may be appropriately determined based on the development conditions of the developing device to be used. In general, the toner concentration in the developer is preferably in the range of 1% by mass to 15% by mass. If the toner concentration is less than 1% by mass, the image density becomes too thin, while if the toner concentration exceeds 15% by mass, toner scattering may occur in the developing device, causing problems such as dirt inside the device and toner adhesion to the background parts of transfer paper, etc. A more preferable toner concentration is in the range of 3% by mass to 10% by mass.
トナーとしては、重合法、粉砕分級法、溶融造粒法、スプレー造粒法など従来公知の方法で製造したものが使用できる。具体的には、熱可塑性樹脂を主成分とする結着樹脂中に、着色剤、離型剤、帯電制御剤等を含有させたものが好適に使用できる。 Toners that can be used are those manufactured by conventional methods such as polymerization, pulverization and classification, melt granulation, and spray granulation. Specifically, toners that contain colorants, release agents, charge control agents, etc. in a binder resin that is mainly composed of a thermoplastic resin are preferably used.
トナーの粒子径は、一般に、コールターカウンターによる体積平均粒子径で５μｍ以上１５μｍ以下の範囲が好ましく、７μｍ以上１２μｍ以下の範囲がより好ましい。 The particle size of the toner is generally preferably in the range of 5 μm to 15 μm, and more preferably in the range of 7 μm to 12 μm, as measured by a Coulter counter.
トナー表面には、必要により、改質剤を添加してもよい。改質剤としては、例えば、シリカ、アルミナ、酸化亜鉛、酸化チタン、酸化マグネシウム、ポリメチルメタクリレート等が挙げられる。これらの１種又は２種以上を組み合わせて使用できる。 If necessary, a modifier may be added to the toner surface. Examples of modifiers include silica, alumina, zinc oxide, titanium oxide, magnesium oxide, polymethyl methacrylate, etc. One or more of these may be used in combination.
キャリアとトナーとの混合は、従来公知の混合装置を用いることができる。例えばヘンシェルミキサー、Ｖ型混合機、タンブラーミキサー、ハイブリタイザー等を用いることができる。 The carrier and toner can be mixed using a conventional mixing device. For example, a Henschel mixer, a V-type mixer, a tumbler mixer, a hybridizer, etc. can be used.
本発明の現像剤を用いた現像方法に特に限定はないが、磁気ブラシ現像法が好適である。図４に、磁気ブラシ現像を行う現像装置の一例を示す概説図を示す。図４に示す現像装置は、複数の磁極を内蔵した回転自在の現像ローラ３と、現像部へ搬送される現像ローラ３上の現像剤量を規制する規制ブレード６と、水平方向に平行に配置され、互いに逆向きに現像剤を撹拌搬送する２本のスクリュー１，２と、２本のスクリュー１，２の間に形成され、両スクリューの両端部において、一方のスクリューから他方のスクリューに現像剤の移動を可能とし、両端部以外での現像剤の移動を防ぐ仕切板４とを備える。 There is no particular limitation on the developing method using the developer of the present invention, but a magnetic brush development method is preferable. Figure 4 shows a schematic diagram of an example of a developing device that performs magnetic brush development. The developing device shown in Figure 4 is equipped with a rotatable developing roller 3 that incorporates multiple magnetic poles, a regulating blade 6 that regulates the amount of developer on the developing roller 3 that is transported to the development section, two screws 1 and 2 that are arranged in parallel in the horizontal direction and stir and transport the developer in opposite directions, and a partition plate 4 that is formed between the two screws 1 and 2 and allows the developer to move from one screw to the other screw at both ends of the two screws, while preventing the developer from moving anywhere other than at both ends.
２本のスクリュー１，２は、螺旋状の羽根１３，２３が同じ傾斜角で軸部１１，２１に形成されたものであって、不図示の駆動機構によって同方向に回転し、現像剤を互いに逆方向に搬送する。そして、スクリュー１，２の両端部において一方のスクリューから他方のスクリューに現像剤が移動する。これによりトナーとキャリアからなる現像剤は装置内を常に循環し撹拌されることになる。 The two screws 1 and 2 have helical blades 13 and 23 formed on shafts 11 and 21 at the same inclination angle, and are rotated in the same direction by a drive mechanism (not shown), transporting developer in opposite directions. Developer moves from one screw to the other at both ends of the screws 1 and 2. This causes the developer, which is made up of toner and carrier, to constantly circulate and be stirred within the device.
一方、現像ローラ３は、表面に数μｍの凹凸を付けた金属製の筒状体の内部に、磁極発生手段として、現像磁極Ｎ１、搬送磁極Ｓ１、剥離磁極Ｎ２、汲み上げ磁極Ｎ３、ブレード磁極Ｓ２の５つの磁極を順に配置した固定磁石を有してなる。現像ローラ３の筒状体が矢印方向に回転すると、汲み上げ磁極Ｎ３の磁力によって、スクリュー１から現像ローラ３へ現像剤が汲み上げられる。現像ローラ３の表面に担持された現像剤は、規制ブレード６により層規制された後、現像領域へ搬送される。 Meanwhile, the developing roller 3 is a metallic cylindrical body having a surface with a few μm of unevenness, and has a fixed magnet with five magnetic poles arranged in order as magnetic pole generating means: a developing magnetic pole N1 , a transport magnetic pole S1 , a peeling magnetic pole N2 , a pumping magnetic pole N3 , and a blade magnetic pole S2 . When the cylindrical body of the developing roller 3 rotates in the direction of the arrow, the developer is pumped up from the screw 1 to the developing roller 3 by the magnetic force of the pumping magnetic pole N3 . The developer carried on the surface of the developing roller 3 is layer-regulated by a regulating blade 6, and then transported to the development area.
現像領域では、直流電圧に交流電圧を重畳したバイアス電圧が転写電圧電源８から現像ローラ３に印加される。バイアス電圧の直流電圧成分は、感光体ドラム５表面の背景部電位と画像部電位との間の電位とされる。また、背景部電位と画像部電位とは、バイアス電圧の最大値と最小値との間の電位とされる。バイアス電圧のピーク間電圧は０．５ｋＶ～５ｋＶの範囲が好ましく、周波数は１ｋＨｚ～１０ｋＨｚの範囲が好ましい。またバイアス電圧の波形は矩形波、サイン波、三角波などいずれであってもよい。これによって、現像領域においてトナー及びキャリアが振動し、トナーが感光体ドラム５上の静電潜像に付着して現像がなされる。 In the development area, a bias voltage consisting of a DC voltage superimposed on an AC voltage is applied from the transfer voltage power source 8 to the development roller 3. The DC voltage component of the bias voltage is set to a potential between the background potential and the image potential on the surface of the photoconductor drum 5. The background potential and the image potential are set to potentials between the maximum and minimum values of the bias voltage. The peak-to-peak voltage of the bias voltage is preferably in the range of 0.5 kV to 5 kV, and the frequency is preferably in the range of 1 kHz to 10 kHz. The waveform of the bias voltage may be any of a square wave, a sine wave, a triangular wave, and the like. This causes the toner and carrier to vibrate in the development area, and the toner adheres to the electrostatic latent image on the photoconductor drum 5, resulting in development.
その後現像ローラ３上の現像剤は、搬送磁極Ｓ１によって装置内部に搬送され、剥離電極Ｎ２によって現像ローラ３から剥離して、スクリュー１，２によって装置内を再び循環搬送され、現像に供していない現像剤と混合撹拌される。そして汲み上げ極Ｎ３によって、新たに現像剤がスクリュー１から現像ローラ３へ供給される。 The developer on the developing roller 3 is then transported into the device by the transport magnetic pole S1 , peeled off from the developing roller 3 by the peeling electrode N2 , and circulated again within the device by the screws 1 and 2, where it is mixed and stirred with the developer not being used for development. Then, new developer is supplied from the screw 1 to the developing roller 3 by the pumping pole N3 .
なお、図４に示した実施形態では現像ローラ３に内蔵された磁極は５つであったが、現像剤の現像領域での移動量を一層大きくしたり、汲み上げ性等を一層向上させるために、磁極を８極や１０極、１２極と増やしてももちろん構わない。 In the embodiment shown in FIG. 4, the developing roller 3 has five magnetic poles, but it is of course possible to increase the number of magnetic poles to eight, ten, or twelve in order to increase the amount of developer movement in the development area or to improve the pumping performance.
（実施例１）
原料として、Ｆｅ２Ｏ３（平均粒径：０．６μｍ）１０．０ｋｇ、Ｍｎ３Ｏ４（平均粒径：３．４μｍ）３．８ｋｇ、ＭｇＦｅ２Ｏ４（平均粒径：３．２μｍ）２．６ｋｇ、ＣａＣＯ３（平均粒径：０．６μｍ）０．０８１ｋｇ、Ｎｂ２Ｏ５（平均粒径：３．５μｍ）０．０９５ｋｇを純水５．４ｋｇ中に分散し、還元剤としてカーボンブラックを３０ｇ、分散剤としてポリカルボン酸アンモニウム系分散剤を１３９ｇ、アンモニア水（２５ｗｔ％水溶液）を５ｇ添加して混合物とした。この混合物を湿式ボールミル（メディア径２ｍｍ）により粉砕処理し、混合スラリーを得た。
この混合スラリーをスプレードライヤーにて約１４０℃の熱風中に噴霧し、粒径１０μｍ～７５μｍの乾燥造粒物を得た。この造粒物から粒径２５μｍ以下の微小な粒子は篩を用いて除去した。
この造粒物を、電気炉に投入し１２００℃まで４．５時間かけて昇温した。その後１２００℃で３時間保持することにより焼成を行った。電気炉内の酸素濃度は昇温の段階では１０００００ｐｐｍ、冷却の段階では１５０００ｐｐｍとなるよう、炉内の酸素濃度を調整した。
得られた焼成物をハンマーミルで解粒した後に振動篩を用いて分級し、平均粒子径３５．７μｍのキャリア芯材を得た。
Example 1
As raw materials, 10.0 kg of Fe2O3 (average particle size: 0.6 μm), 3.8 kg of Mn3O4 (average particle size: 3.4 μm), 2.6 kg of MgFe2O4 (average particle size: 3.2 μm), 0.081 kg of CaCO3 (average particle size: 0.6 μm), and 0.095 kg of Nb2O5 (average particle size: 3.5 μm) were dispersed in 5.4 kg of pure water, and 30 g of carbon black was added as a reducing agent, 139 g of a polycarboxylate ammonium dispersant as a dispersant, and 5 g of ammonia water (25 wt% aqueous solution) were added to obtain a mixture. This mixture was pulverized by a wet ball mill (media diameter 2 mm) to obtain a mixed slurry.
This mixed slurry was sprayed into hot air at about 140° C. using a spray dryer to obtain dried granules with a particle size of 10 μm to 75 μm. Fine particles with a particle size of 25 μm or less were removed from the granules using a sieve.
The granulated material was placed in an electric furnace and heated to 1200° C. over 4.5 hours. Then, the material was sintered by holding the material at 1200° C. for 3 hours. The oxygen concentration in the electric furnace was adjusted to 100,000 ppm during the heating stage and 15,000 ppm during the cooling stage.
The obtained fired product was disintegrated with a hammer mill and then classified with a vibrating sieve to obtain a carrier core material having an average particle size of 35.7 μm.
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。 The composition, powder characteristics, shape characteristics, magnetic properties, etc. of the obtained carrier core material were measured using the methods described below. The measurement results are shown in Table 1.
次に、このようにして得られたキャリア芯材の表面を樹脂で被覆してキャリアを作製した。具体的には、シリコーン樹脂４５０質量部と、（２－アミノエチル）アミノプロピルトリメトキシシラン９質量部とを、溶媒としてのトルエン４５０質量部に溶解してコート溶液を作製した。このコート溶液を、流動床型コーティング装置を用いてキャリア芯材５００００質量部に塗布し、温度３００℃の電気炉で加熱してキャリアを得た。以下の実施例及び比較例についても同様にしてキャリアを得た。 The surface of the carrier core material thus obtained was then coated with resin to produce a carrier. Specifically, 450 parts by mass of silicone resin and 9 parts by mass of (2-aminoethyl)aminopropyltrimethoxysilane were dissolved in 450 parts by mass of toluene as a solvent to produce a coating solution. This coating solution was applied to 50,000 parts by mass of the carrier core material using a fluidized bed coating device, and the carrier was obtained by heating in an electric furnace at a temperature of 300°C. Carriers were obtained in the same manner for the following examples and comparative examples.
得られたキャリアと平均粒子径５．０μｍ程度のトナーとを、ポットミルを用いて所定時間混合し、二成分系の電子写真現像剤を得た。この場合、キャリアとトナーとをトナーの質量／（トナーおよびキャリアの質量）＝５／１００となるように調整した。以下、全ての実施例、比較例についても同様にして現像剤を得た。得られた現像剤について後述の実機評価を行った。評価結果を表１に合わせて示す。 The obtained carrier and toner having an average particle size of about 5.0 μm were mixed for a specified time using a pot mill to obtain a two-component electrophotographic developer. In this case, the carrier and toner were adjusted so that the mass of the toner/(mass of the toner and carrier) was 5/100. Developers were obtained in the same manner for all the following examples and comparative examples. The obtained developer was evaluated using an actual machine as described below. The evaluation results are also shown in Table 1.
（実施例２）
焼成工程における電気炉温度を１２４０℃に変更した以外は実施例１と同様にして平均粒子径３６．２μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
Example 2
A carrier core material having an average particle size of 36.2 μm was obtained in the same manner as in Example 1, except that the electric furnace temperature in the firing step was changed to 1240° C.
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（実施例３）
焼成工程における電気炉温度を１２１０℃に変更し、電気炉内の酸素濃度は昇温の段階では１０００００ｐｐｍ、冷却の段階では２５０００ｐｐｍとなるよう、炉内の酸素濃度を調整した以外は実施例１と同様にして平均粒子径３６．１μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
Example 3
A carrier core material having an average particle diameter of 36.1 μm was obtained in the same manner as in Example 1, except that the electric furnace temperature in the firing process was changed to 1210° C. and the oxygen concentration in the electric furnace was adjusted so that it was 100,000 ppm during the heating stage and 25,000 ppm during the cooling stage.
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（実施例４）
原料として、Ｆｅ２Ｏ３（平均粒径：０．６μｍ）１０．０ｋｇ、Ｍｎ３Ｏ４（平均粒径：３．４μｍ）３．８ｋｇ、ＭｇＦｅ２Ｏ４（平均粒径：３．２μｍ）２．６ｋｇ、ＣａＣＯ３（平均粒径：０．６μｍ）０．１２２ｋｇ、Ｎｂ２Ｏ５（平均粒径：３．５μｍ）０．１４３ｋｇを使用した以外は実施例３と同様にして平均粒子径３５．６μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
Example 4
A carrier core material with an average particle diameter of 35.6 μm was obtained in the same manner as in Example 3 , except that the raw materials used were 10.0 kg of Fe 2 O 3 (average particle diameter: 0.6 μm), 3.8 kg of Mn 3 O 4 (average particle diameter: 3.4 μm), 2.6 kg of MgFe 2 O 4 (average particle diameter: 3.2 μm), 0.122 kg of CaCO 3 (average particle diameter: 0.6 μm), and 0.143 kg of Nb 2 O 5 (average particle diameter: 3.5 μm).
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（実施例５）
原料として、Ｆｅ２Ｏ３（平均粒径：０．６μｍ）１０．０ｋｇ、Ｍｎ３Ｏ４（平均粒径：３．４μｍ）３．８ｋｇ、ＭｇＦｅ２Ｏ４（平均粒径：３．２μｍ）２．６ｋｇ、ＣａＣＯ３（平均粒径：０．６μｍ）０．１６３ｋｇ、Ｎｂ２Ｏ５（平均粒径：３．５μｍ）０．１９０ｋｇを使用した以外は実施例３と同様にして平均粒子径３５．１μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
Example 5
A carrier core material with an average particle diameter of 35.1 μm was obtained in the same manner as in Example 3 , except that the raw materials used were 10.0 kg of Fe 2 O 3 (average particle diameter: 0.6 μm), 3.8 kg of Mn 3 O 4 (average particle diameter: 3.4 μm), 2.6 kg of MgFe 2 O 4 (average particle diameter: 3.2 μm), 0.163 kg of CaCO 3 (average particle diameter: 0.6 μm), and 0.190 kg of Nb 2 O 5 (average particle diameter: 3.5 μm).
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（実施例６）
原料として、Ｆｅ２Ｏ３（平均粒径：０．６μｍ）１０．０ｋｇ、Ｍｎ３Ｏ４（平均粒径：３．４μｍ）３．８ｋｇ、ＭｇＦｅ２Ｏ４（平均粒径：３．２μｍ）２．６ｋｇ、ＣａＣＯ３（平均粒径：０．６μｍ）０．０６１ｋｇ、Ｎｂ２Ｏ５（平均粒径：３．５μｍ）０．０７１ｋｇを使用した以外は実施例３と同様にして平均粒子径３５．２μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
Example 6
A carrier core material with an average particle diameter of 35.2 μm was obtained in the same manner as in Example 3 , except that the raw materials used were 10.0 kg of Fe 2 O 3 (average particle diameter: 0.6 μm), 3.8 kg of Mn 3 O 4 (average particle diameter: 3.4 μm), 2.6 kg of MgFe 2 O 4 (average particle diameter: 3.2 μm), 0.061 kg of CaCO 3 (average particle diameter: 0.6 μm), and 0.071 kg of Nb 2 O 5 (average particle diameter: 3.5 μm).
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（実施例７）
原料として、Ｆｅ２Ｏ３（平均粒径：０．６μｍ）１０．０ｋｇ、Ｍｎ３Ｏ４（平均粒径：３．４μｍ）３．８ｋｇ、ＭｇＦｅ２Ｏ４（平均粒径：３．２μｍ）２．６ｋｇ、ＣａＣＯ３（平均粒径：０．６μｍ）０．０４１ｋｇ、Ｎｂ２Ｏ５（平均粒径：３．５μｍ）０．０４８ｋｇを使用した以外は実施例３と同様にして平均粒子径３６．１μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
(Example 7)
A carrier core material with an average particle diameter of 36.1 μm was obtained in the same manner as in Example 3 , except that the raw materials used were 10.0 kg of Fe 2 O 3 (average particle diameter: 0.6 μm), 3.8 kg of Mn 3 O 4 (average particle diameter: 3.4 μm), 2.6 kg of MgFe 2 O 4 (average particle diameter: 3.2 μm), 0.041 kg of CaCO 3 (average particle diameter: 0.6 μm), and 0.048 kg of Nb 2 O 5 (average particle diameter: 3.5 μm).
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（実施例８）
原料として、Ｆｅ２Ｏ３（平均粒径：０．６μｍ）１０．０ｋｇ、Ｍｎ３Ｏ４（平均粒径：３．４μｍ）３．８ｋｇ、ＭｇＦｅ２Ｏ４（平均粒径：３．２μｍ）２．６ｋｇ、ＣａＣＯ３（平均粒径：０．６μｍ）０．０８１ｋｇ、Ｎｂ２Ｏ５（平均粒径：３．５μｍ）０．０７１ｋｇを使用した以外は実施例３と同様にして平均粒子径３５．７μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。また図２にキャリア芯材のＳＥＭ写真を示す。
(Example 8)
A carrier core material with an average particle diameter of 35.7 μm was obtained in the same manner as in Example 3 , except that the raw materials used were 10.0 kg of Fe 2 O 3 (average particle diameter: 0.6 μm), 3.8 kg of Mn 3 O 4 (average particle diameter: 3.4 μm), 2.6 kg of MgFe 2 O 4 (average particle diameter: 3.2 μm), 0.081 kg of CaCO 3 (average particle diameter: 0.6 μm), and 0.071 kg of Nb 2 O 5 (average particle diameter: 3.5 μm).
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1. Also, a SEM photograph of the carrier core material is shown in Figure 2.
（実施例９）
原料として、Ｆｅ２Ｏ３（平均粒径：０．６μｍ）１０．０ｋｇ、Ｍｎ３Ｏ４（平均粒径：３．４μｍ）３．８ｋｇ、ＭｇＦｅ２Ｏ４（平均粒径：３．２μｍ）２．６ｋｇ、ＣａＣＯ３（平均粒径：０．６μｍ）０．０８１ｋｇ、Ｎｂ２Ｏ５（平均粒径：３．５μｍ）０．０４７ｋｇを使用した以外は実施例３と同様にして平均粒子径３５．５μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
(Example 9)
A carrier core material with an average particle diameter of 35.5 μm was obtained in the same manner as in Example 3 , except that the raw materials used were 10.0 kg of Fe 2 O 3 (average particle diameter: 0.6 μm), 3.8 kg of Mn 3 O 4 (average particle diameter: 3.4 μm), 2.6 kg of MgFe 2 O 4 (average particle diameter: 3.2 μm), 0.081 kg of CaCO 3 (average particle diameter: 0.6 μm), and 0.047 kg of Nb 2 O 5 (average particle diameter: 3.5 μm).
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（実施例１０）
原料として、Ｆｅ２Ｏ３（平均粒径：０．６μｍ）１０．０ｋｇ、Ｍｎ３Ｏ４（平均粒径：３．４μｍ）３．８ｋｇ、ＭｇＦｅ２Ｏ４（平均粒径：３．２μｍ）２．６ｋｇ、ＣａＣＯ３（平均粒径：０．６μｍ）０．０８１ｋｇ、Ｎｂ２Ｏ５（平均粒径：３．５μｍ）０．０２４ｋｇを使用した以外は実施例３と同様にして平均粒子径３５．３μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
(Example 10)
A carrier core material with an average particle diameter of 35.3 μm was obtained in the same manner as in Example 3 , except that the raw materials used were 10.0 kg of Fe 2 O 3 (average particle diameter: 0.6 μm), 3.8 kg of Mn 3 O 4 (average particle diameter: 3.4 μm), 2.6 kg of MgFe 2 O 4 (average particle diameter: 3.2 μm), 0.081 kg of CaCO 3 (average particle diameter: 0.6 μm), and 0.024 kg of Nb 2 O 5 (average particle diameter: 3.5 μm).
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（比較例１）
原料として、Ｆｅ２Ｏ３（平均粒径：０．６μｍ）９．５ｋｇ、Ｍｎ３Ｏ４（平均粒径：２．０μｍ）４．２ｋｇ、ＭｇＦｅ２Ｏ４（平均粒径：３．２μｍ）２．７ｋｇ、ＳｒＣＯ３（平均粒径：０．６μｍ）０．１８１ｋｇを純水５．４ｋｇ中に分散し、還元剤としてカーボンブラックを５７ｇ、分散剤としてポリカルボン酸アンモニウム系分散剤を８２ｇ、塩酸（３５ｗｔ％水溶液）を３２ｇ添加して混合物とした。この混合物を湿式ボールミル（メディア径２ｍｍ）により粉砕処理し、混合スラリーを得た。
この混合スラリーをスプレードライヤーにて約１４０℃の熱風中に噴霧し、粒径１０μｍ～７５μｍの乾燥造粒物を得た。この造粒物から粒径２５μｍ以下の微小な粒子は篩を用いて除去した。
この造粒物を、電気炉に投入し１２００℃まで４．５時間かけて昇温した。その後１２００℃で３時間保持することにより焼成を行った。電気炉内の酸素濃度は昇温の段階では１００００ｐｐｍ、冷却の段階では１５０００ｐｐｍとなるよう、炉内の酸素濃度を調整した。
得られた焼成物をハンマーミルで解粒した後に振動篩を用いて分級し、平均粒子径３４．９μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
(Comparative Example 1)
As raw materials, 9.5 kg of Fe2O3 (average particle size: 0.6 μm), 4.2 kg of Mn3O4 (average particle size: 2.0 μm), 2.7 kg of MgFe2O4 (average particle size: 3.2 μm), and 0.181 kg of SrCO3 (average particle size: 0.6 μm) were dispersed in 5.4 kg of pure water, and 57 g of carbon black as a reducing agent, 82 g of a polycarboxylate ammonium dispersant as a dispersant, and 32 g of hydrochloric acid (35 wt % aqueous solution) were added to obtain a mixture. This mixture was pulverized by a wet ball mill (media diameter 2 mm) to obtain a mixed slurry.
This mixed slurry was sprayed into hot air at about 140° C. using a spray dryer to obtain dried granules with a particle size of 10 μm to 75 μm. Fine particles with a particle size of 25 μm or less were removed from the granules using a sieve.
The granulated material was placed in an electric furnace and heated to 1200° C. over 4.5 hours. Then, the material was sintered by holding the material at 1200° C. for 3 hours. The oxygen concentration in the electric furnace was adjusted to 10,000 ppm during the heating stage and 15,000 ppm during the cooling stage.
The obtained fired product was disintegrated with a hammer mill and then classified with a vibrating sieve to obtain a carrier core material having an average particle size of 34.9 μm.
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（比較例２）
Ｆｅ２Ｏ３（平均粒径：０．８μｍ）を５０．０ｍｏｌ、Ｍｎ３Ｏ４（平均粒径：２．０μｍ）をＭｎＯ換算で５０．０ｍｏｌとなるように秤量し、ローラーコンパクターでペレット化した。得られたペレットを大気雰囲気の条件下、８５０℃にてロータリー式の焼成炉で仮焼成をおこなった。乾式ビーズミルで６時間粉砕し、仮焼原料（平均粒径：２．２μｍ）を得た。この仮焼原料１６．４ｋｇとＳｒＣＯ３（平均粒径：０．６μｍ）０．１９７ｋｇを純水５．５ｋｇ中に分散し、還元剤としてカーボンブラックを４９ｇ、分散剤としてポリカルボン酸アンモニウム系分散剤を９８ｇ添加して混合物とした。この混合物を湿式ボールミル（メディア径２ｍｍ）により粉砕処理し、混合スラリーを得た。
この混合スラリーをスプレードライヤーにて約１４０℃の熱風中に噴霧し、粒径１０μｍ～７５μｍの乾燥造粒物を得た。この造粒物から粒径３０μｍ以下の微小な粒子は篩を用いて除去した。
この造粒物を、電気炉に投入し１２００℃まで４．５時間かけて昇温した。その後１２００℃で３時間保持することにより焼成を行った。電気炉内の酸素濃度は１５０００ｐｐｍとなるよう、炉内の酸素濃度を調整した。
得られた焼成物をハンマーミルで解粒した後に振動篩を用いて分級し、平均粒子径３４．８μｍの焼成物を得た。
次いで、得られた焼成物を大気雰囲気下３８０℃で１時間保持することにより酸化処理（高抵抗化処理）を行い、キャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
(Comparative Example 2)
Fe 2 O 3 (average particle size: 0.8 μm) was weighed out to 50.0 mol, and Mn 3 O 4 (average particle size: 2.0 μm) was weighed out to 50.0 mol in terms of MnO, and pelletized with a roller compactor. The obtained pellets were pre-fired in a rotary firing furnace at 850° C. under atmospheric conditions. The pellets were pulverized for 6 hours with a dry bead mill to obtain a pre-fired raw material (average particle size: 2.2 μm). 16.4 kg of the pre-fired raw material and 0.197 kg of SrCO 3 (average particle size: 0.6 μm) were dispersed in 5.5 kg of pure water, and 49 g of carbon black was added as a reducing agent and 98 g of polycarboxylate ammonium dispersant was added as a dispersant to obtain a mixture. The mixture was pulverized with a wet ball mill (media diameter 2 mm) to obtain a mixed slurry.
This mixed slurry was sprayed into hot air at about 140° C. using a spray dryer to obtain dried granules with a particle size of 10 μm to 75 μm. Fine particles with a particle size of 30 μm or less were removed from the granules using a sieve.
The granulated material was placed in an electric furnace and heated to 1200° C. over 4.5 hours. Then, the material was sintered by holding the material at 1200° C. for 3 hours. The oxygen concentration in the electric furnace was adjusted to 15000 ppm.
The obtained fired product was disintegrated in a hammer mill and then classified using a vibrating sieve to obtain a fired product having an average particle size of 34.8 μm.
Next, the obtained fired product was subjected to an oxidation treatment (resistance increasing treatment) by holding it at 380° C. for 1 hour in an air atmosphere, thereby obtaining a carrier core material.
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（比較例３）
原料として、Ｎｂ２Ｏ５を添加しなかったこと以外は実施例３と同様にして平均粒子径３４．３μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。また図３にキャリア芯材のＳＥＭ写真を示す。
(Comparative Example 3)
A carrier core material having an average particle size of 34.3 μm was obtained in the same manner as in Example 3, except that Nb 2 O 5 was not added as a raw material.
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1. Also, a SEM photograph of the carrier core material is shown in Figure 3.
（比較例４）
原料として、ＣａＣＯ３を添加しなかったこと以外は実施例３と同様にして平均粒子径３５．９μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
(Comparative Example 4)
A carrier core material having an average particle size of 35.9 μm was obtained in the same manner as in Example 3, except that CaCO 3 was not added as a raw material.
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（比較例５）
原料として、Ｆｅ２Ｏ３（平均粒径：０．６μｍ）１０．０ｋｇ、Ｍｎ３Ｏ４（平均粒径：３．４μｍ）３．８ｋｇ、ＭｇＦｅ２Ｏ４（平均粒径：３．２μｍ）２．６ｋｇ、ＳｒＣＯ３（平均粒径：０．６μｍ）０．１１９ｋｇ、Ｎｂ２Ｏ５（平均粒径：３．５μｍ）０．０９５ｋｇを純水５．４ｋｇ中に分散し、還元剤としてカーボンブラックを３０ｇ、分散剤としてポリカルボン酸アンモニウム系分散剤を１３９ｇ、アンモニア水（２５ｗｔ％水溶液）を５ｇ添加して混合物とした。この混合物を湿式ボールミル（メディア径２ｍｍ）により粉砕処理し、混合スラリーを得た以外は実施例３と同様にして平均粒子径３４．５μｍのキャリア芯材を得た。
得られたキャリア芯材の組成、粉体特性、形状特性、磁気特性などを後述の方法で測定した。測定結果を表１に示す。
(Comparative Example 5)
As raw materials, 10.0 kg of Fe2O3 (average particle size: 0.6 μm), 3.8 kg of Mn3O4 (average particle size: 3.4 μm), 2.6 kg of MgFe2O4 (average particle size: 3.2 μm), 0.119 kg of SrCO3 (average particle size: 0.6 μm), and 0.095 kg of Nb2O5 (average particle size: 3.5 μm) were dispersed in 5.4 kg of pure water, and 30 g of carbon black was added as a reducing agent, 139 g of polycarboxylate ammonium dispersant as a dispersant, and 5 g of ammonia water (25 wt% aqueous solution) were added to obtain a mixture. This mixture was pulverized by a wet ball mill (media diameter 2 mm) to obtain a mixed slurry, and the same procedure as in Example 3 was used to obtain a carrier core material with an average particle size of 34.5 μm.
The composition, powder characteristics, shape characteristics, magnetic characteristics, etc. of the obtained carrier core material were measured by the methods described below. The measurement results are shown in Table 1.
（組成分析）
（Ｆｅの分析）
鉄元素を含むキャリア芯材を秤量し、塩酸と硝酸の混酸水に溶解させた。この溶液を蒸発乾固させた後、硫酸水を添加して再溶解し過剰な塩酸と硝酸とを揮発させる。この溶液に固体Ａｌを添加して液中のＦｅ３＋を全てＦｅ２＋に還元する。続いて、この溶液中のＦｅ２＋イオンの量を過マンガン酸カリウム溶液で電位差滴定することにより定量分析し、Ｆｅ（Ｆｅ２＋）の滴定量を求めた。
（Ｍｎの分析）
キャリア芯材のＭｎ含有量は、ＪＩＳ Ｇ１３１１－１９８７記載のフェロマンガン分析方法（電位差滴定法）に準拠して定量分析を行った。本明細書に記載したキャリア芯材のＭｎ含有量は、このフェロマンガン分析方法（電位差滴定法）で定量分析し得られたＭｎ量である。
（Ｍｇの分析）
キャリア芯材のＭｇ含有量は、以下の方法で分析を行った。キャリア芯材を酸溶液中で溶解し、ＩＣＰにて定量分析を行った。本明細書に記載したキャリア芯材のＭｇ含有量は、このＩＣＰによる定量分析で得られたＭｇ量である。
（Ｃａの分析）
キャリア芯材のＣａ含有量は、Ｍｇの分析同様にＩＣＰによる定量分析で行った。
（Ｎｂの分析）
キャリア芯材のＮｂ含有量は、Ｍｇの分析同様にＩＣＰによる定量分析で行った。
（Ｓｒの分析）
キャリア芯材のＳｒ含有量は、Ｍｇの分析同様にＩＣＰによる定量分析で行った。
(Composition Analysis)
(Fe Analysis)
The carrier core material containing iron element was weighed and dissolved in a mixed acid solution of hydrochloric acid and nitric acid. After evaporating this solution to dryness, sulfuric acid water was added to redissolve it and volatilize the excess hydrochloric acid and nitric acid. Solid Al was added to this solution to reduce all Fe3 + in the liquid to Fe2 + . Then, the amount of Fe2 + ions in this solution was quantitatively analyzed by potentiometric titration with potassium permanganate solution to determine the titration amount of Fe (Fe2 + ).
(Mn Analysis)
The Mn content of the carrier core material was quantitatively analyzed in accordance with the ferromanganese analysis method (potentiometric titration method) described in JIS G1311-1987. The Mn content of the carrier core material described in this specification is the Mn amount obtained by quantitative analysis using this ferromanganese analysis method (potentiometric titration method).
(Mg Analysis)
The Mg content of the carrier core material was analyzed by the following method: the carrier core material was dissolved in an acid solution and quantitatively analyzed by ICP. The Mg content of the carrier core material described in this specification is the amount of Mg obtained by this quantitative analysis by ICP.
(Ca Analysis)
The Ca content of the carrier core material was quantitatively analyzed by ICP in the same manner as in the analysis of Mg.
(Nb Analysis)
The Nb content of the carrier core material was quantitatively analyzed by ICP in the same manner as in the analysis of Mg.
(Sr Analysis)
The Sr content of the carrier core material was quantitatively analyzed by ICP in the same manner as in the analysis of Mg.
後述する表１における組成値（ｍｏｌ％）は以下の手順で算出した。
Ｆｅ、ＭｎおよびＭｇの分析値から、Ｆｅ２Ｏ３、ＭｎＯおよびＭｇＯのそれぞれのモル量を計算し、Ｆｅ２Ｏ３、ＭｎＯおよびＭｇＯの合計が１００ｍｏｌ％となるようにＦｅ２Ｏ３、ＭｎＯおよびＭｇＯのそれぞれのモル比（ｍｏｌ％）を算出した。次に、Ｆｅ２Ｏ３、ＭｎＯおよびＭｇＯの合計量（１００ｍｏｌ％）に対するＣａ、ＮｂおよびＳｒのそれぞれのモル比（ｍｏｌ％）を算出した。
The composition values (mol %) in Table 1 described later were calculated by the following procedure.
From the analytical values of Fe, Mn, and Mg, the molar amounts of Fe2O3 , MnO, and MgO were calculated, and the molar ratios (mol%) of Fe2O3 , MnO, and MgO were calculated so that the total of Fe2O3 , MnO, and MgO was 100 mol%. Next, the molar ratios (mol%) of Ca , Nb , and Sr relative to the total amount (100 mol%) of Fe2O3, MnO, and MgO were calculated.
（見掛け密度ＡＤ）
キャリア芯材の見掛け密度はＪＩＳ Ｚ ２５０４に準拠して測定した。
(Apparent density AD)
The apparent density of the carrier core material was measured in accordance with JIS Z 2504.
（流動度ＦＲ）
キャリア芯材の流動度はＪＩＳ Ｚ ２５０２に準拠して測定した。
(Flow Rate FR)
The fluidity of the carrier core material was measured in accordance with JIS Z 2502.
（体積平均粒子径Ｄ５０）
キャリア芯材の体積平均粒子径Ｄ５０は、レーザー回折式粒度分布測定装置（日機装社製「マイクロトラックＭｏｄｅｌ９３２０－Ｘ１００」）を用いて体積基準の累積５０％粒子径として測定した。
(Volume average particle diameter D50 )
The volume average particle diameter D 50 of the carrier core material was measured as the cumulative 50% particle diameter on a volume basis using a laser diffraction particle size distribution measuring device (Microtrac Model 9320-X100 manufactured by Nikkiso Co., Ltd.).
（細孔容積）
細孔容積の測定については、以下の通り行った。評価装置は、Ｑｕａｎｔａｃｈｒｏｍｅ社製のＰＯＲＥＭＡＳＴＥＲ－６０ＧＴを使用した。具体的には、測定条件としては、Ｃｅｌｌ Ｓｔｅｍ Ｖｏｌｕｍｅ：０．５ｃｍ３、Ｈｅａｄｐｒｅｓｓｕｒｅ：２０ＰＳＩＡ、水銀の表面張力：４８５．００ｅｒｇ／ｃｍ２、水銀の接触角：１３０．００ｄｅｇｒｅｅｓ、高圧測定モード：Ｆｉｘｅｄ Ｒａｔｅ、Ｍｏｔｅｒ Ｓｐｅｅｄ：１、高圧測定レンジ：２０．００～１００００．００ＰＳＩとし、サンプル１．２００ｇを秤量して０．５ｃｍ３のセルに充填して測定を行った。また、１００００．００ＰＳＩ時の容積Ｂ（ｃｍ３／ｇ）から１００ＰＳＩ時の容積Ａ（ｃｍ３／ｇ）を差し引いた値を、細孔容積とした。
(Pore volume)
The pore volume was measured as follows. The evaluation device used was a POREMASTER-60GT manufactured by Quantachrome. Specifically, the measurement conditions were Cell Stem Volume: 0.5 cm 3 , Head pressure: 20 PSIA, Surface tension of mercury: 485.00 erg/cm 2 , Contact angle of mercury: 130.00 degrees, High pressure measurement mode: Fixed Rate, Motor Speed: 1, High pressure measurement range: 20.00 to 10000.00 PSI, and 1.200 g of the sample was weighed and filled into a 0.5 cm 3 cell for measurement. The pore volume was calculated by subtracting the volume A (cm 3 /g) at 100 PSI from the volume B (cm 3 /g) at 10,000.00 PSI.
（最大山谷深さＲｚ、平均長さＲＳｍ）
超深度カラー３Ｄ形状測定顕微鏡（「ＶＫ－Ｘ１００」株式会社キーエンス製）を用い、１００倍対物レンズで表面を観察して求めた。具体的には、まず、表面の平坦な粘着テープにフェライト粒子を固定し、１００倍対物レンズで測定視野を決定した後、オートフォーカス機能を用いて焦点を粘着テープ面に調整した。フェライト粒子を固定した平坦な粘着テープ面に対し、垂直方向（Ｚ方向）からレーザー光線を照射し、面のＸ方向Ｙ方向に走査した。また、表面からの反射光の強度が最大となった時のレンズの高さ位置をつなぎ合わせることでＺ方向のデータを取得した。これらＸ、ＹおよびＺ方向の位置データをつなぎ合わせフェライト粒子表面の３次元形状を得た。なお、フェライト粒子表面の３次元形状の取り込みにはオート撮影機能を用いた。
各パラメータの測定には、粒子粗さ検査ソフトウェア（三谷商事製）を用いて行った。まず、前処理として、得られたフェライト粒子表面の３次元形状の粒子認識と形状選別を行った。粒子認識は以下の方法で行った。
撮影によって得られた３次元形状のうち、Ｚ方向の最大値を１００％、最小値を０％として最大値から最小値までの間を１００等分する。この１００～３５％にあたる領域を抽出し、独立した領域の輪郭を粒子輪郭として認識した。次に形状選別で粗大、微小、会合などの粒子を除外した。この形状選別を行うことで以降に行う極率補正時の誤差を小さくすることができる。具体的には面積相当径２８μｍ以下、３８μｍ以上、針状比１．１５以上に該当する粒子を除外した。ここで針状比とは粒子の最大長／対角幅の比から算出したパラメータであり、対角幅とは最大長に平行な２本の直線で粒子を挟んだときの２直線の最短距離を表す。
つぎに表面の３次元形状から解析に用いる部分の取り出しを行った。まず上記の方法で認識した粒子輪郭から求められる重心を中心として１５．０μｍの正方形を描く。描いた正方形の中に２１本の平行線を引き、その線分上にあたる粗さ曲線を２１本分取り出した。
フェライト粒子は略球形状であるため、取り出した粗さ曲線は、バックグラウンドとして一定の曲率を持っている。このため、バックグラウンドの補正として、最適な二次曲線をフィッティングし、粗さ曲線から差し引く補正を行った。この場合、ローパスフィルタを１．５μｍの強度で適用し、カットオフ値λを８０μｍとした。
また、解析に用いるキャリア芯材の平均粒子径については３２μｍ～３４μｍに限定した。このように測定対象となるキャリア芯材の平均粒子径を狭い範囲に限定することで、曲率補正の際に生じる残渣による誤差を小さくすることができる。
(Maximum peak/valley depth Rz, average length RSm)
The surface was observed with a 100x objective lens using an ultra-deep color 3D shape measuring microscope ("VK-X100" manufactured by Keyence Corporation). Specifically, first, ferrite particles were fixed to a flat adhesive tape on the surface, and the measurement field of view was determined with a 100x objective lens, and then the focus was adjusted to the adhesive tape surface using the autofocus function. A laser beam was irradiated from the vertical direction (Z direction) to the flat adhesive tape surface on which the ferrite particles were fixed, and the surface was scanned in the X and Y directions. In addition, data in the Z direction was obtained by connecting the height positions of the lens when the intensity of the reflected light from the surface was maximized. The position data in the X, Y, and Z directions were connected to obtain the three-dimensional shape of the ferrite particle surface. In addition, an auto-photography function was used to capture the three-dimensional shape of the ferrite particle surface.
The parameters were measured using particle roughness inspection software (Mitani Shoji Co., Ltd.). First, as a pretreatment, particle recognition and shape selection of the three-dimensional shape of the obtained ferrite particle surface were performed. Particle recognition was performed in the following manner.
Of the three-dimensional shape obtained by photography, the maximum value in the Z direction is set to 100%, the minimum value to 0%, and the range between the maximum value and the minimum value is divided into 100 equal parts. The region corresponding to 100-35% is extracted, and the outline of the independent region is recognized as the particle outline. Next, particles that are large, small, associated, etc. are excluded by shape selection. By performing this shape selection, it is possible to reduce errors during the curvature correction performed later. Specifically, particles with an area equivalent diameter of 28 μm or less, 38 μm or more, and an acicular ratio of 1.15 or more are excluded. Here, the acicular ratio is a parameter calculated from the ratio of the maximum length/diagonal width of the particle, and the diagonal width represents the shortest distance between two straight lines when a particle is sandwiched between two straight lines parallel to the maximum length.
Next, the portion to be used for analysis was extracted from the three-dimensional shape of the surface. First, a 15.0 μm square was drawn with the center of gravity determined from the particle outline recognized by the above method as the center. 21 parallel lines were drawn within the square, and 21 roughness curves corresponding to the line segments were extracted.
Since the ferrite particles are approximately spherical, the roughness curve has a certain curvature as the background. Therefore, to correct the background, an optimal quadratic curve was fitted and subtracted from the roughness curve. In this case, a low-pass filter was applied with a strength of 1.5 μm, and the cutoff value λ was set to 80 μm.
In addition, the average particle diameter of the carrier core material used in the analysis was limited to 32 μm to 34 μm. By limiting the average particle diameter of the carrier core material to be measured to a narrow range in this way, it is possible to reduce errors due to residues that occur during curvature correction.
最大山谷深さＲｚは、粗さ曲線の中で最も高い山の高さと最も深い谷の深さの和として求めた。最大高さＲｚの算出には、各パラメータの平均値として、３０粒子の平均値を用いることとした。 The maximum peak-valley depth Rz was calculated as the sum of the height of the highest peak and the depth of the deepest valley in the roughness curve. The average value of 30 particles was used as the average value of each parameter to calculate the maximum height Rz.
平均長さＲＳｍは、粗さ曲線のうち、谷と山の組み合わせを一つの要素と規定し、それぞれの要素の長さを平均したものである。平均長さＲＳｍの算出には、各パラメータの平均値として、３０粒子の平均値を用いることとした。 The average length RSm is calculated by averaging the length of each element, with a combination of a valley and a peak on the roughness curve defined as one element. To calculate the average length RSm, the average value of 30 particles was used as the average value of each parameter.
以上説明した最大高さＲｚ、平均長さＲＳｍの測定は、ＪＩＳ Ｂ０６０１（２００１年度版）に準拠して行われるものである。 The measurements of maximum height Rz and average length RSm described above are performed in accordance with JIS B0601 (2001 edition).
（磁気特性）
室温専用振動試料型磁力計（ＶＳＭ）（東英工業社製「ＶＳＭ－Ｐ７」）を用いて、外部磁場を０～７９．５８×１０４Ａ／ｍ（１００００エルステッド）の範囲で１サイクル連続的に印加して、磁場７９．５８×１０３Ａ／ｍ（１，０００エルステッド）を印加した際の磁化σ１ｋ、飽和磁化σｓ、残留磁化σｒ、保磁力Ｈｃを測定した。
(Magnetic properties)
Using a room temperature dedicated vibrating sample magnetometer (VSM) ("VSM-P7" manufactured by Toei Kogyo Co., Ltd.), an external magnetic field in the range of 0 to 79.58×10 4 A/m (10,000 Oersted) was continuously applied for one cycle, and the magnetization σ 1k , saturation magnetization σ s , residual magnetization σ r , and coercivity H c when a magnetic field of 79.58×10 3 A/m (1,000 Oersted) was applied were measured.
（ブリッジ式抵抗）
電極として表面を電解研磨した板厚２ｍｍの真鍮板２枚を電極間距離が２ｍｍとなるように配置し、２枚の電極板の間の空隙にキャリア芯材２００ｍｇを装入した後、それぞれの電極板の背後に断面積２４０ｍｍ２の磁石を配置して電極間に被測定粉体のブリッジを形成させた状態で電極間に１０００Ｖ直流電圧を印加し、キャリア芯材を流れる電流値を４端子法により測定した。その電流値と、電極間距離２ｍｍおよび断面積２４０ｍｍ２からキャリア芯材の電気抵抗を算出した。
(bridge resistor)
Two 2 mm thick brass plates with electrolytically polished surfaces were placed as electrodes with an interelectrode distance of 2 mm, and 200 mg of carrier core material was placed in the gap between the two electrode plates. A magnet with a cross-sectional area of 240 mm2 was then placed behind each electrode plate to form a bridge of the powder to be measured between the electrodes. A DC voltage of 1000 V was then applied between the electrodes, and the current flowing through the carrier core material was measured by the four-terminal method. The electrical resistance of the carrier core material was calculated from the current value, the interelectrode distance of 2 mm, and the cross-sectional area of 240 mm2 .
（実機評価）
（現像メモリ）
得られた現像剤を、図４に示す構造の現像装置（現像ローラの周速度Ｖｓ：４０６ｍｍ／ｓｅｃ，感光体ドラムの周速度Ｖｐ：２０５ｍｍ／ｓｅｃ，感光体ドラム－現像ローラ間距離：０．３ｍｍ）に投入し、感光体ドラムの周方向にベタ画像部と非画像部とが隣り合い、その後は広い面積の中間調が続く初期画像を取得し、現像ローラ２周目の現像ローラ１周目のベタ画像が現像された領域とそうでない領域との画像濃度を反射濃度計（東京電色社製の型番ＴＣ－６Ｄ）を用いて測定し、その差を求め下記基準で評価した。結果を表２に示す。
「◎」：０．００３未満
「○」：０．００３以上０．００６未満
「△」：０．００６以上０．０２０未満
「×」：０．０２０以上
(Actual machine evaluation)
(Development memory)
The obtained developer was put into a developing device having a structure shown in Figure 4 (circumferential speed of developing roller Vs: 406 mm/sec, peripheral speed of photosensitive drum Vp: 205 mm/sec, distance between photosensitive drum and developing roller: 0.3 mm), and an initial image was obtained in which solid image areas and non-image areas were adjacent to each other in the circumferential direction of the photosensitive drum, followed by a wide area of intermediate tones. The image density of the area where the solid image of the first rotation of the developing roller was developed and the area where it was not developed on the second rotation of the developing roller was measured using a reflection densitometer (Model TC-6D, manufactured by Tokyo Denshoku Co., Ltd.), and the difference was determined and evaluated according to the following criteria. The results are shown in Table 2.
"◎": Less than 0.003 "○": 0.003 or more and less than 0.006 "△": 0.006 or more and less than 0.020 "X": 0.020 or more
（濃度ムラ）
前記評価機による評価用画像３枚について１枚当たり５カ所の濃度を反射濃度計（東京電色社製の型番ＴＣ－６Ｄ）を用いて測定し下記基準で評価した。
「◎」：濃度の濃淡差の最大が０．１未満であり、濃度ムラが視認できない。
「○」：濃度の濃淡差の最大が０．１以上０．２未満あり、濃度ムラが視認できない。
「△」：濃度の濃淡差の最大が０．２以上０．３未満あり、濃度ムラが視認できる。
「×」：濃度の濃淡差の最大が０．３以上であり、濃度ムラが視認でき使用できない。
(Uneven density)
The density of five points on each of three evaluation images obtained by the evaluation machine was measured using a reflection densitometer (Model TC-6D, manufactured by Tokyo Denshoku Co., Ltd.) and evaluated according to the following criteria.
"Excellent": The maximum difference in density between light and dark areas is less than 0.1, and density unevenness is not visible.
"◯": The maximum density difference is 0.1 or more and less than 0.2, and density unevenness is not visible.
"B": The maximum density difference is 0.2 or more and less than 0.3, and density unevenness is visible.
"X": The maximum difference in density between light and dark areas is 0.3 or more, and density unevenness is visible, making it unusable.
表１から明らかなように、ＣａとＮｂとを含むＭｎＭｇフェライトから構成される実施例１～１０のキャリア芯材では現像メモリ及び濃度ムラは実使用上問題のないレベルに抑えられていた。 As is clear from Table 1, the development memory and density unevenness of the carrier core materials of Examples 1 to 10, which are made of MnMg ferrite containing Ca and Nb, were suppressed to levels that were not problematic in practical use.
これに対して、Ｓｒを含むＭｎＭｇフェライトから構成される比較例１のキャリア芯材では現像メモリは問題のないレベルに抑えられていたものの濃度ムラは視認でき実使用上問題のあるレベルであった。また、Ｓｒを含むＭｎフェライトから構成される比較例２のキャリア芯材でも現像メモリは実使用上問題のないレベルに抑えられていたものの濃度ムラは視認でき実使用上問題のあるレベルであった。 In contrast, in the carrier core material of Comparative Example 1, which is made of MnMg ferrite containing Sr, the development memory was suppressed to a level that was not a problem, but the unevenness in density was visible and was at a level that was problematic in practical use. In addition, in the carrier core material of Comparative Example 2, which is made of Mn ferrite containing Sr, the development memory was suppressed to a level that was not a problem in practical use, but the unevenness in density was visible and was at a level that was problematic in practical use.
またＣａを含みＮｂを含まないＭｎＭｇフェライトから構成される比較例３のキャリア芯材では濃度ムラは実使用上問題のないレベルに抑えられていたものの現像メモリは実使用上問題のあるレベルであった。また、Ｎｂを含みＣａを含まないＭｎＭｇフェライトから構成される比較例４のキャリア芯材でも濃度ムラは実使用上問題のないレベルに抑えられていたものの現像メモリは実使用上問題のあるレベルであった。 In the carrier core material of Comparative Example 3, which is made of MnMg ferrite containing Ca but not Nb, the unevenness in density was suppressed to a level that does not cause problems in practical use, but the development memory was at a level that causes problems in practical use. In the carrier core material of Comparative Example 4, which is made of MnMg ferrite containing Nb but not Ca, the unevenness in density was suppressed to a level that does not cause problems in practical use, but the development memory was at a level that causes problems in practical use.
ＮｂとＳｒとが含有されたＭｎＭｇフェライトから構成される比較例５のキャリア芯材では現像メモリは問題のないレベルに抑えられていたが濃度ムラは実使用上問題のあるレベルであった。 In the carrier core material of Comparative Example 5, which is composed of MnMg ferrite containing Nb and Sr, the development memory was suppressed to a non-problematic level, but the density unevenness was at a level that was problematic in practical use.
本発明に係るキャリア芯材によれば現像メモリが抑制できると共に、画像の濃度ムラも抑制でき有用である。 The carrier core material of the present invention is useful because it can suppress development memory and also suppress uneven density in images.
３ 現像ローラ
５ 感光体ドラム
3 developing roller 5 photosensitive drum
Claims (10)
Ｃａが０．１ｍｏｌ％以上１．５ｍｏｌ％以下の範囲、
Ｎｂが０．１ｍｏｌ％以上１．５ｍｏｌ％以下の範囲、
含有されていることを特徴とするキャリア芯材。 A carrier core material made of ferrite particles represented by a composition formula (MnO) x (MgO) y ( Fe2O3 ) z (wherein x is 30 mol% or more and 55 mol% or less, y is more than 0 mol % and 20 mol% or less, z is 40 mol% or more and 60 mol% or less, and x+y+z=100 mol%),
Ca is in the range of 0.1 mol% or more and 1.5 mol% or less,
Nb is in the range of 0.1 mol% or more and 1.5 mol% or less,
A carrier core material comprising:
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| JP2018141864A (en) | 2017-02-28 | 2018-09-13 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material |
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| JP2022071924A (en) | 2020-10-29 | 2022-05-17 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material |
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| JPS6140823A (en) * | 1984-07-31 | 1986-02-27 | Dowa Mining Co Ltd | Hydrothermal synthesis of magnetoplumbite type ferrite |
| JPS62297856A (en) * | 1986-06-18 | 1987-12-25 | Hitachi Metals Ltd | Ferrite carrier for electrophotographic development |
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| JP2007031210A (en) | 2005-07-27 | 2007-02-08 | Nec Tokin Corp | Mn-Zn FERRITE |
| JP2008096975A (en) | 2006-09-14 | 2008-04-24 | Ricoh Co Ltd | Electrophotographic developer carrier and developer |
| US20100078587A1 (en) | 2008-09-30 | 2010-04-01 | Tdk Corporation | NiMnZn-BASED FERRITE |
| JP2018025702A (en) | 2016-08-11 | 2018-02-15 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core |
| JP2018141864A (en) | 2017-02-28 | 2018-09-13 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material |
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| JP2021028705A (en) | 2019-08-10 | 2021-02-25 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core |
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