US3754989A - Electrical resistor coated with flame-proof coating composition - Google Patents
Electrical resistor coated with flame-proof coating composition Download PDFInfo
- Publication number
- US3754989A US3754989A US00094198A US3754989DA US3754989A US 3754989 A US3754989 A US 3754989A US 00094198 A US00094198 A US 00094198A US 3754989D A US3754989D A US 3754989DA US 3754989 A US3754989 A US 3754989A
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- US
- United States
- Prior art keywords
- coating
- coating composition
- composition
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- titanium dioxide
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- Expired - Lifetime
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- 239000008199 coating composition Substances 0.000 title abstract description 49
- 239000000375 suspending agent Substances 0.000 claims abstract description 38
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 30
- 239000002245 particle Substances 0.000 claims abstract description 21
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 12
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 12
- 229910052901 montmorillonite Inorganic materials 0.000 claims description 8
- 125000005210 alkyl ammonium group Chemical group 0.000 claims description 5
- 229910001887 tin oxide Inorganic materials 0.000 claims description 5
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 claims description 4
- 239000011521 glass Substances 0.000 claims description 3
- 239000000758 substrate Substances 0.000 claims description 3
- 239000005909 Kieselgur Substances 0.000 claims description 2
- 239000004927 clay Substances 0.000 claims description 2
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical group O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 claims description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 abstract description 53
- 238000000576 coating method Methods 0.000 abstract description 34
- 239000011248 coating agent Substances 0.000 abstract description 27
- 239000000203 mixture Substances 0.000 abstract description 27
- 239000004408 titanium dioxide Substances 0.000 abstract description 27
- 229910052783 alkali metal Inorganic materials 0.000 abstract description 18
- 150000001340 alkali metals Chemical class 0.000 abstract description 18
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 abstract description 10
- 229910052792 caesium Inorganic materials 0.000 abstract description 4
- 229910052744 lithium Inorganic materials 0.000 abstract description 4
- 229910052700 potassium Inorganic materials 0.000 abstract description 4
- 229910052701 rubidium Inorganic materials 0.000 abstract description 4
- 229910052708 sodium Inorganic materials 0.000 abstract description 3
- 239000010408 film Substances 0.000 description 17
- 229910001413 alkali metal ion Inorganic materials 0.000 description 14
- 239000000463 material Substances 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 239000000945 filler Substances 0.000 description 6
- 239000011253 protective coating Substances 0.000 description 6
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 6
- 239000006185 dispersion Substances 0.000 description 5
- 239000000049 pigment Substances 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 230000006378 damage Effects 0.000 description 4
- 238000005204 segregation Methods 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007062 hydrolysis Effects 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- 239000004615 ingredient Substances 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical group CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 150000001339 alkali metal compounds Chemical class 0.000 description 2
- -1 alkyl orthosilicate Chemical compound 0.000 description 2
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000002939 deleterious effect Effects 0.000 description 2
- SWXVUIWOUIDPGS-UHFFFAOYSA-N diacetone alcohol Chemical compound CC(=O)CC(C)(C)O SWXVUIWOUIDPGS-UHFFFAOYSA-N 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 239000003063 flame retardant Substances 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910052605 nesosilicate Inorganic materials 0.000 description 2
- 150000004762 orthosilicates Chemical class 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 230000002829 reductive effect Effects 0.000 description 2
- 150000003839 salts Chemical group 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- NHTMVDHEPJAVLT-UHFFFAOYSA-N Isooctane Chemical compound CC(C)CC(C)(C)C NHTMVDHEPJAVLT-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 229910003251 Na K Inorganic materials 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 125000005907 alkyl ester group Chemical group 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- MPMSMUBQXQALQI-UHFFFAOYSA-N cobalt phthalocyanine Chemical compound [Co+2].C12=CC=CC=C2C(N=C2[N-]C(C3=CC=CC=C32)=N2)=NC1=NC([C]1C=CC=CC1=1)=NC=1N=C1[C]3C=CC=CC3=C2[N-]1 MPMSMUBQXQALQI-UHFFFAOYSA-N 0.000 description 1
- 229910021488 crystalline silicon dioxide Inorganic materials 0.000 description 1
- 230000003413 degradative effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- JVSWJIKNEAIKJW-UHFFFAOYSA-N dimethyl-hexane Natural products CCCCCC(C)C JVSWJIKNEAIKJW-UHFFFAOYSA-N 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 239000012767 functional filler Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- IGLNJRXAVVLDKE-UHFFFAOYSA-N rubidium atom Chemical compound [Rb] IGLNJRXAVVLDKE-UHFFFAOYSA-N 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 230000000391 smoking effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 239000008096 xylene Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
- C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
- C03C17/3411—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions with at least two coatings of inorganic materials
- C03C17/3417—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions with at least two coatings of inorganic materials all coatings being oxide coatings
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
- C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
- C03C17/3411—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions with at least two coatings of inorganic materials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/002—Inhomogeneous material in general
- H01B3/006—Other inhomogeneous material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C1/00—Details
- H01C1/02—Housing; Enclosing; Embedding; Filling the housing or enclosure
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C1/00—Details
- H01C1/02—Housing; Enclosing; Embedding; Filling the housing or enclosure
- H01C1/034—Housing; Enclosing; Embedding; Filling the housing or enclosure the housing or enclosure being formed as coating or mould without outer sheath
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2217/00—Coatings on glass
- C03C2217/40—Coatings comprising at least one inhomogeneous layer
- C03C2217/43—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase
- C03C2217/44—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase characterized by the composition of the continuous phase
- C03C2217/45—Inorganic continuous phases
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2217/00—Coatings on glass
- C03C2217/40—Coatings comprising at least one inhomogeneous layer
- C03C2217/43—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase
- C03C2217/46—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase characterized by the dispersed phase
- C03C2217/47—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase characterized by the dispersed phase consisting of a specific material
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2217/00—Coatings on glass
- C03C2217/40—Coatings comprising at least one inhomogeneous layer
- C03C2217/43—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase
- C03C2217/46—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase characterized by the dispersed phase
- C03C2217/47—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase characterized by the dispersed phase consisting of a specific material
- C03C2217/475—Inorganic materials
- C03C2217/477—Titanium oxide
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2217/00—Coatings on glass
- C03C2217/40—Coatings comprising at least one inhomogeneous layer
- C03C2217/43—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase
- C03C2217/46—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase characterized by the dispersed phase
- C03C2217/47—Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase characterized by the dispersed phase consisting of a specific material
- C03C2217/475—Inorganic materials
- C03C2217/478—Silica
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/25—Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
- Y10T428/259—Silicic material
Definitions
- ABSTRACT An electrical resistor coated with a coating composition
- a coating composition comprising a) an at least partially hydrolyzed tetra alkyl orthosilicate, b) aluminum oxide, c) titanium dioxide, d) silicon dioxide, and e) a suspension agent, wherein said titanium dioxide and said suspension agent are added to the composition as dry particles having agglomerates greater than about 1 micron in size, and wherein the alkali metal content of said coating composition is such that, upon curing, a coating prepared from said composition contains f) less than about 0.05% Na, g) less than about 0.05 K, h) less than about 0.01% Li, i) less than about 0.001% Cs, and j) less than about 0.001% Rb, all percentages being in terms of the oxides of the respective alkali metals.
- the present invention relates to coating compositions for electrical resistors particularly, film resistors. More specifically, the present invention relates to flame-resistant coatings adapted for the protection of electrical film resistors against burning and smoking due to overload.
- these film resistors have come into wide use. Normally, these film resistors comprise a substrate such as glass coated with a thin film of resistor material such as tin oxide, for example. Also, it is known in the art to overcoat these film resistors with a protective layer. The prior art is faced with the problem, however, that these protective coatings very often burn and are destroyed due to the heat resulting from severe overloads on the film resistors. This burning of the resistor coating now only results in the destruction of the resistor itself, but, very often, results in damage to adjacent elements in the system in which it is employed. The consequent damage to electrical equipment and systems from this burning of resistor coatings has led to an intensive search for a flame-proof coating, which will withstand the heat arising from sudden, severe overloads on the resistor.
- the film resistors containing the protective coatings of the prior art suffer from the further disadvantage that upon overload the protective coatings not only burn, but also promote external arcing and in some cases tend to short out the circuit in which they are contained. Accordingly, an intensive search has been conducted for a resistor protective coating which will not burn under severe overload and which will inhibit external arcing and assist in opening the overload circuit.
- resistors It has recently been proposed to coat resistors with a composition containing tetraalkyl orthosilicates, aluminum oxide,-titanium dioxide, silicon dioxide and a suspension agent. This composition has been found to be more effective than the prior art protective coatings as a flame-resistant resistor coating.
- Titanium dioxide and suspension agents such as the bentones are employed in a variety of applications in the coating art and in other areas. They are usually supplied by the manufacturer and utilized in the art in a cowled form. Cowling is the process of forming a dispersion of a particulate solid in a carrier liquid at high speed and high shear. Titanium dioxide frequently utilized as a filler and pigment and suspension agents are normally most effectively employed in small particle size form. The most advantageous mode of achieving small particle size is by the aforedescribed process of cowling. Upon cowling, dispersions of titanium dioxide and the suspension agents are produced containing particles of sub-micron size.
- Cowling is also believed to be necessary in the preparation of dispersions of these materials and coating compositions containing these dispersions to facilitate the overall mixing process and to avoid segregation of the particles.
- segregation is meant the phenomenon whereby the particles agglomerate and settle out of the mixture in which they are incorporated.
- cowling filler and suspension materials dispersions containing extremely small particle size suspensions are obtained which do not tend to settle out or segregate on standing.
- the active surface area of the titanium dioxide and suspension agent is greatly increased due to the small particle size of the suspended material, thereby contributing to its catalytic effect on the degradation of the coating composition. It is to be understood, however, that I do not intend to be bound by this proposed theory.
- a cured coating prepared from the coating composition contains less than about 0.05 percent sodium, less than about 0.05 percent potassium, less than about 0.01 percent lithium, less than about 0.001 percent cesium, and less than about 0.001 percent of rubidium, (expressed in terms of the oxides) the moisture resistance and overall stability of the coating composition is greatly enhanced.
- the coating composition of the present invention comprises an at least partially hydrolyzed tetraalkyl orthosilicate, aluminum oxide, titanium dioxide, silicon dioxide and a suspension agent wherein the titanium dioxide and suspension agent are added to the composition as dry particles having a particle agglomerate size greater than about 1 micron and wherein the alkali metal ion content of the coating composition is such that upon curing the coating prepared from the composition contains less than the percentages of alkali metal ions set forth above.
- any tetraalkyl orthosilicate in an at least partially pre-hydrolyzed form may be employed.
- a preferred orthosilicate is tetraethyl orthosilicate.
- the degree of hydrolysis, except as discussed above in connection with gel formation, is not overly critical.
- an orthosilicate hydrolyzed to an extent of from about to about 90 percent may be employed in the compositions of the present invention.
- amounts of the tetraalkyl orthosilicate ranging from about 5 to about 55 percent may be employed.
- other alkyl esters may be employed such as, for example, the methyl, propyl, butyl, esters, etc.
- Amounts of aluminum oxide ranging from about 4 to about 95 percent may be included in the coating composition of the present invention.
- Silicon dioxide is added to the coating composition for the purposes of inhibiting the tendency of the coatings prepared from these compositions to crack during and following curing.
- Ser. No. 724,220 filed Apr. 25, 1968, now abandoned, I have described the inhibitory effect of silicon dioxide on this tendency of tetraalkyl orthosilicate based coating compositions to crack.
- amounts ranging from about 1 to about 48 percent of crystalline silicon dioxide having a particle size in the range of from about 100 to about 325 mesh may be employed.
- the titanium dioxide component acts as a functional filler in the coating composition of the present invention.
- the TiO also aids in the processing and handling of the composition by operating as a suspension agent.
- the TiO also functions as a pigment in the coating composition. Generally, amounts of TiO, ranging from about 1 to about 45 percent may be employed. Additional conventional fillers and/or pigments may be added to the composition where desired.
- Suitable suspension agents include the organic derivatives of the various montmorillonites such as the alkyl ammonium montmorillonites, etc., commonly known as the bentones. Additional suspension agents include amorphous silica, clays such as the montmorillonites and diatomaceous earths such as kieselguhr. Generally, the alkyl ammonium montmorillonites are the pre ferred suspension agents and may be employed in an amount ranging from 0.1 to 2.0 percent.
- particle agglomerates having a size in the range of from about 1 to about microns are suitable. Agglomerate sizes in this range have been found to combine the best properties of facilitating processing of the coating composition and increased pot-life.
- agglomerate is meant a cluster or bundle of particles which exist in the composition as discrete units.
- a solvent may be added to the coating composition.
- Suitable solvents include the lower alkanols, methylethyl ketone, dimethyl formarnide, diacetone alcohol, dimethyl sulfoxide, toluene, xylene, trichloroethylene, tetrachloroethylene, trichloroethane, N-methylpyrrolidone, iso-octane, hexane, benzene, dioxane, etc.
- Isopropanol is the preferred solvent.
- amounts of solvent ranging from about 0 to about 20 percent may be employed.
- cowling is advantageous for another reason. Cowling is a time consuming and relatively expensive process. By eliminating this step, the overall expense and time involved in preparing the coating compositions of the present invention are greatly reduced.
- the alkali metal ion content of the coating composition be adjusted such that cured coatings prepared from these compositions contain less than the hereinabove indicated maximum percentage limits.
- Conventional suspension agents generally contain fairly high percentages of alkali metal ions. Accordingly, a reduction in the amount of suspension agent employed over those heretofore suggested, re sults in a corresponding reduction in the alkali metal ion content. It is to be understood, however, that the amounts of any of the ingredients of the coating compositions may be adjusted to achieve the required alkali metal ion concentrations.
- the ingredients of the coating composition of the invention may be preliminarily purified to reduce their alkali metal ion content prior to incorpo' ration in the coating composition.
- This purification may take the form of cold water or hot water leaching since most alkali metal compounds are water soluble. Those that are not water soluble are less likely to have an effect on the moisture resistance of the ultimate coating. It is to be understood, however, that any purification method may be employed to reduce the alkali metal ion content.
- the moisture resistance of the coated resistors are tested in accordance with the standard method Ml- L-STD-202B. Method 106A (May 31, 1957). The results of this test are normally expressed in terms of A R percentages. The maximum A R allowed in each particular case is dependent on the size of the resistor. Generally, A R percentages below about 1 percent have been accepted as meeting the MIL-STD requirements for moisture resistance.
- the coating compositions of the present invention may be coated on the resistor according to any of the conventional coating methods; e.g., dip, spray, brush; roller, etc. Generally sufficient material is applied to the resistor to give a final cured coating between 5 and mils, preferably between 5 and 7 mils, thick. It is especially preferred, although not mandatory, to apply two coats to the resistor.
- the coating is cured by heating at elevated temperatures, usually up to about 250C.
- a coating composition was prepared according to the following recipe:
- the suspension agent (Bentone 27) was also employed in a non-cowled form and had a particleagglomerate size of about 50 microns (325 mesh).
- the coating composition had a pot-life of more than six weeks.
- the composition was double-coated on glass-tin oxide film 1K resistors having a 4 watt rated power and cured at 250C. to yield a coating 10 mils thick.
- the cured coating was found to have a total alkali metal content (as oxides) of approximately 1.02 grams or 0.04 percent.
- the coated resistors were tested for moisture resistance according to MlL-STD202B Method 106A and found to have an average A R of 1.0 percent.
- the resistor Upon being subjected to an overload of times rated power, the resistor opened the circuit with no burning or flaming. There was no evidence of external arcing and the coating was found to be non-conductive during overload.
- EXAMPLE 2 A coating composition was prepared according to the following recipe:
- the thus prepared coating composition was coated on resistors identical to that and under the same conditions as in Example 1.
- the cured coating was found to have an alkali metal content (as oxides) of 10.0 grams or 0.4 percent.
- the moisture resistance test indicated an average A R of 3.0 percent, indicating that the increased alkali metal content in the composition deleteriously affected its moisture resistance.
- the coating Upon being subjected to an overload of 100 times rated power the coating was found to be conductive and there was evidence of some external arcing, thereby indicating the deleterious effects of high alkali metal content on the dielectric properties of the coating.
- a coating composition was prepared according to the following recipe: Component Parts by Weight Aluminum oxide 2160 The particle size of the suspension agent was about 0.] micron while the TiO had an average particle size of about 0.05 micron.
- the resulting composition was found to have a potlife of only about 1 week, before it deteriorated into a thick, viscous gel, thereby indicating the deleterious effect of cowled suspension agents and the titanium dioxide on the pot-life of the composition.
- An electrical resistor coated with a nonconductive coating composition consisting essentially of a. an at least partially hydrolized tetraalkyl ortho silicate present in an amount of from about to about 55 percent,
- titanium dioxide present in an amount of from about I to about 45 percent
- silicon dioxide present in an amount of from about 1 to about 48 percent
- a suspension agent present in an amount of from about 0.1 to about 2.0 percent, said percentages being present by weight, wherein said titanium dioxide and said suspension agent are present in the composition as agglomerates greater than about 1 micron in size, and wherein the alkali metal content of said coating composition is such that a cured coating contains less than about 0.05 percent Na, less than about 0.05% K, less than about 0.01% Li, less than about 0.001% Cs, and less than about 0.001% Rb, said percentages of said alkali metals being by weight, based on the total composition, in terms of the oxides of the respective alkali metals.
- suspension agent is selected from the group consisting of alkyl ammonium montmorillonites, amorphous silica, clays and diatomaceous earth.
Abstract
An electrical resistor coated with a coating composition comprising a) an at least partially hydrolyzed tetraalkyl orthosilicate, b) aluminum oxide, c) titanium dioxide, d) silicon dioxide, and e) a suspension agent, wherein said titanium dioxide and said suspension agent are added to the composition as dry particles having agglomerates greater than about 1 micron in size, and wherein the alkali metal content of said coating composition is such that, upon curing, a coating prepared from said composition contains f) less than about 0.05% Na, g) less than about 0.05 K, h) less than about 0.01% Li, i) less than about 0.001% Cs, and j) less than about 0.001% Rb, all percentages being in terms of the oxides of the respective alkali metals.
Description
Unite States Patent [191 Bockstie, Jr.
[ Aug. 28, 1973 1 ELECTRICAL RESISTOR COATED WITH FLAME-PROOF COATING COMPOSITION [75] Inventor: Lawrence G. Bockstle, Jr., Bradford,
[21] Appl. No.: 94,198
Related US. Application Data [62] Division of Ser. No. 724,271, April 25, 1968, Pat. No.
[56] References Cited UNITED STATES PATENTS 3,487,349 12/1969 Halloran 117/137 3,412,063 11/1968 Jarboe et al. 106/3835 4/1960 Davis 338/308 5/1964 Pritkin et a1. 338/308 Primary Examiner-Cameron K. Weiffenbach Attorney-Sughrue, Rothwell, Mion, Zinn and Macpeak [57] ABSTRACT An electrical resistor coated with a coating composition comprising a) an at least partially hydrolyzed tetra alkyl orthosilicate, b) aluminum oxide, c) titanium dioxide, d) silicon dioxide, and e) a suspension agent, wherein said titanium dioxide and said suspension agent are added to the composition as dry particles having agglomerates greater than about 1 micron in size, and wherein the alkali metal content of said coating composition is such that, upon curing, a coating prepared from said composition contains f) less than about 0.05% Na, g) less than about 0.05 K, h) less than about 0.01% Li, i) less than about 0.001% Cs, and j) less than about 0.001% Rb, all percentages being in terms of the oxides of the respective alkali metals.
6 Claims, No Drawings ELECTRICAL RESISTOR COATED WITH F LAME-PROOF COATING COMPOSITION CROSS REFERENCE TO A RELATED APPLICATION This is a division of application, Ser. No. 724,271, filed Apr. 25, 1968 now US. Pat. No. 3,598,617.
BACKGROUND OF THE INVENTION The present invention relates to coating compositions for electrical resistors particularly, film resistors. More specifically, the present invention relates to flame-resistant coatings adapted for the protection of electrical film resistors against burning and smoking due to overload.
Recently, electrical film resistors have come into wide use. Normally, these film resistors comprise a substrate such as glass coated with a thin film of resistor material such as tin oxide, for example. Also, it is known in the art to overcoat these film resistors with a protective layer. The prior art is faced with the problem, however, that these protective coatings very often burn and are destroyed due to the heat resulting from severe overloads on the film resistors. This burning of the resistor coating now only results in the destruction of the resistor itself, but, very often, results in damage to adjacent elements in the system in which it is employed. The consequent damage to electrical equipment and systems from this burning of resistor coatings has led to an intensive search for a flame-proof coating, which will withstand the heat arising from sudden, severe overloads on the resistor.
The film resistors containing the protective coatings of the prior art suffer from the further disadvantage that upon overload the protective coatings not only burn, but also promote external arcing and in some cases tend to short out the circuit in which they are contained. Accordingly, an intensive search has been conducted for a resistor protective coating which will not burn under severe overload and which will inhibit external arcing and assist in opening the overload circuit.
It has been proposed to add several conventional flame-retardants to film resistor protective coatings. These efforts, however, have consistently met with failure. Many of these conventional flame-retardants were ineffective to inhibit burning at the extremely high temperatures (400600C.) attained in film resistors under high overload.
It has recently been proposed to coat resistors with a composition containing tetraalkyl orthosilicates, aluminum oxide,-titanium dioxide, silicon dioxide and a suspension agent. This composition has been found to be more effective than the prior art protective coatings as a flame-resistant resistor coating.
Although constituting an advance over the prior art, these recently proposed coating compositions are not free from drawbacks.
Titanium dioxide and suspension agents such as the bentones are employed in a variety of applications in the coating art and in other areas. They are usually supplied by the manufacturer and utilized in the art in a cowled form. Cowling is the process of forming a dispersion of a particulate solid in a carrier liquid at high speed and high shear. Titanium dioxide frequently utilized as a filler and pigment and suspension agents are normally most effectively employed in small particle size form. The most advantageous mode of achieving small particle size is by the aforedescribed process of cowling. Upon cowling, dispersions of titanium dioxide and the suspension agents are produced containing particles of sub-micron size. Cowling is also believed to be necessary in the preparation of dispersions of these materials and coating compositions containing these dispersions to facilitate the overall mixing process and to avoid segregation of the particles. By segregation is meant the phenomenon whereby the particles agglomerate and settle out of the mixture in which they are incorporated. By cowling filler and suspension materials, dispersions containing extremely small particle size suspensions are obtained which do not tend to settle out or segregate on standing.
However, in the particular case of flame-proof resistor coating compositions containing tetraalkyl orthosilicates, aluminum oxide, silicon dioxide and titanium dioxide, it has been found that the utilization of cowled titanium dioxide and suspension agents results in a reduction of the pot-life of the coating composition. The mechanism by which the pot-life is reduced is not completely understood. It is theorized, however, that the titanium dioxide and suspension agent act as catalysts in the composition, exerting a degradative effect on the system. It is believed that titanium dioxide and many of the conventional suspension agents catalyze or promote the hydrolysis of the tetraalkyl orthosilicate component of the coating composition to such an extent that the excess alkanol produced by this hydrolysis functions as a gel-forming agent. It will be readily apparent that the formation of a viscous gel in the coating composition will deteteriously affect its coating properties. Measures must then be taken such as dilution with additional solvent to break the gel and render it processable as a coating composition. Dilution, however, will have an adverse effect on the properties of the ultimate coating prepared from the diluted composition.
By employing a cowled material, the active surface area of the titanium dioxide and suspension agent is greatly increased due to the small particle size of the suspended material, thereby contributing to its catalytic effect on the degradation of the coating composition. It is to be understood, however, that I do not intend to be bound by this proposed theory.
It has been further found that the presence of alkali metal ions in the composition has an adverse effect on the moisture resistance of coatings prepared from these compositions and otherwise contributes to the degradation of the coating. The conventional suspension agents normally supplied in the industry often contain a relatively high percentage of alkali metal ions. The utilization of relatively large amounts of suspension agents and other coating components containing excessive amounts of alkali metal will deteteriously affect the moisture resistance of the resulting coating.
BRIEF DESCRIPTION OF THE INVENTION I have found that employing a non-cowled titanium dioxide filler and suspension agents having particle agglomerate sizes greater than about 1 micron greatly increases the pot-life of the tetraalkyl orthosilicate base flame-proof coating compositions to which they are added.
I have further found that by adjusting the alkali metal ion content of the coating composition such that a cured coating prepared from the coating composition contains less than about 0.05 percent sodium, less than about 0.05 percent potassium, less than about 0.01 percent lithium, less than about 0.001 percent cesium, and less than about 0.001 percent of rubidium, (expressed in terms of the oxides) the moisture resistance and overall stability of the coating composition is greatly enhanced.
Briefly, the coating composition of the present invention comprises an at least partially hydrolyzed tetraalkyl orthosilicate, aluminum oxide, titanium dioxide, silicon dioxide and a suspension agent wherein the titanium dioxide and suspension agent are added to the composition as dry particles having a particle agglomerate size greater than about 1 micron and wherein the alkali metal ion content of the coating composition is such that upon curing the coating prepared from the composition contains less than the percentages of alkali metal ions set forth above.
DETAILED DESCRIPTION OF THE INVENTION Generally, any tetraalkyl orthosilicate in an at least partially pre-hydrolyzed form may be employed. A preferred orthosilicate is tetraethyl orthosilicate. The degree of hydrolysis, except as discussed above in connection with gel formation, is not overly critical. Generally, an orthosilicate hydrolyzed to an extent of from about to about 90 percent may be employed in the compositions of the present invention. Generally, amounts of the tetraalkyl orthosilicate ranging from about 5 to about 55 percent may be employed. In addition to tetraethyl orthosilicate, other alkyl esters may be employed such as, for example, the methyl, propyl, butyl, esters, etc.
Amounts of aluminum oxide ranging from about 4 to about 95 percent may be included in the coating composition of the present invention.
Silicon dioxide is added to the coating composition for the purposes of inhibiting the tendency of the coatings prepared from these compositions to crack during and following curing. In my co-pending application, Ser. No. 724,220, filed Apr. 25, 1968, now abandoned, I have described the inhibitory effect of silicon dioxide on this tendency of tetraalkyl orthosilicate based coating compositions to crack. Generally, amounts ranging from about 1 to about 48 percent of crystalline silicon dioxide having a particle size in the range of from about 100 to about 325 mesh may be employed.
The titanium dioxide component acts as a functional filler in the coating composition of the present invention. In addition to its function as a filler, the TiO, also aids in the processing and handling of the composition by operating as a suspension agent. The TiO, also functions as a pigment in the coating composition. Generally, amounts of TiO, ranging from about 1 to about 45 percent may be employed. Additional conventional fillers and/or pigments may be added to the composition where desired.
Any conventional suspension agent may be employed in the coating compositions of the present invention. Suitable suspension agents include the organic derivatives of the various montmorillonites such as the alkyl ammonium montmorillonites, etc., commonly known as the bentones. Additional suspension agents include amorphous silica, clays such as the montmorillonites and diatomaceous earths such as kieselguhr. Generally, the alkyl ammonium montmorillonites are the pre ferred suspension agents and may be employed in an amount ranging from 0.1 to 2.0 percent.
As stated above, adding the titanium dioxide filler and suspension agent in non-cowled form such that the particle agglomerate size of the additives is greater than about 1 micron greatly increases the pot-life of the overall coating composition. Generally, particle agglomerates having a size in the range of from about 1 to about microns are suitable. Agglomerate sizes in this range have been found to combine the best properties of facilitating processing of the coating composition and increased pot-life. By agglomerate is meant a cluster or bundle of particles which exist in the composition as discrete units.
If desired, a solvent may be added to the coating composition. Suitable solvents include the lower alkanols, methylethyl ketone, dimethyl formarnide, diacetone alcohol, dimethyl sulfoxide, toluene, xylene, trichloroethylene, tetrachloroethylene, trichloroethane, N-methylpyrrolidone, iso-octane, hexane, benzene, dioxane, etc. Isopropanol is the preferred solvent. Generally, amounts of solvent ranging from about 0 to about 20 percent may be employed.
The elimination of the cowling step in the processing the titanium dioxide and suspension agents is advantageous for another reason. Cowling is a time consuming and relatively expensive process. By eliminating this step, the overall expense and time involved in preparing the coating compositions of the present invention are greatly reduced.
It will be recalled from the discussion above that cowling of titanium dioxide and conventional suspension agents is believed to be necessary in the art in order to facilitate incorporation in other systems and to avoid segregation or settling-out of the particles. Although the utilization of non-cowled materials has been found to produce advantageous results as explained above, the disadvantageous results normally associated with non-cowled materials are not produced in connection with the tetraalkyl orthosilicate based coating compositions of the present invention. That is, even though non-cowled titanium dioxide and suspension agents are employed in the compositions of the invention, no problems such as incomplete mixing, segregation, etc., arise.
It is essential in order to obtain a moisture resistant coating meeting the exacting requirements of the electrical industry, that the alkali metal ion content of the coating composition be adjusted such that cured coatings prepared from these compositions contain less than the hereinabove indicated maximum percentage limits. Conventional suspension agents generally contain fairly high percentages of alkali metal ions. Accordingly, a reduction in the amount of suspension agent employed over those heretofore suggested, re sults in a corresponding reduction in the alkali metal ion content. It is to be understood, however, that the amounts of any of the ingredients of the coating compositions may be adjusted to achieve the required alkali metal ion concentrations.
Alternatively, the ingredients of the coating composition of the invention may be preliminarily purified to reduce their alkali metal ion content prior to incorpo' ration in the coating composition. This purification may take the form of cold water or hot water leaching since most alkali metal compounds are water soluble. Those that are not water soluble are less likely to have an effect on the moisture resistance of the ultimate coating. It is to be understood, however, that any purification method may be employed to reduce the alkali metal ion content.
The exact mechanism by which the alkali metal ions affect the moisture resistance and otherwise contribute to the overall degradation of the coatings of the present invention is not completely undstood. It is theorized that a high alkali metal ion content will render the coating electrically conductive at high temperatures encountered during overload. Moreover, in the presence of high humidity free alkalies cause electrolysis of the tin oxide film. Being conductive, the resistor would not open the circuit under severe overload thereby leading to short circuiting and damage to other components in the circuit.
These problems are more apt to occur if the alkali metal is in salt form and capable of being liberated in free ionic form in the presence of water. If the alkali metals are chemically bound in complex insoluble silicates, for example, there is less danger of deterioration of the coating in the presence of moisture. However, in cases of severe overload, these complex alkali metal compounds may decompose to loose the alkali metals in salt form. Hence, it is always desirable to rid the coating composition ingredients of all alkali metal constituents.
The moisture resistance of the coated resistors are tested in accordance with the standard method Ml- L-STD-202B. Method 106A (May 31, 1957). The results of this test are normally expressed in terms of A R percentages. The maximum A R allowed in each particular case is dependent on the size of the resistor. Generally, A R percentages below about 1 percent have been accepted as meeting the MIL-STD requirements for moisture resistance.
The coating compositions of the present invention may be coated on the resistor according to any of the conventional coating methods; e.g., dip, spray, brush; roller, etc. Generally sufficient material is applied to the resistor to give a final cured coating between 5 and mils, preferably between 5 and 7 mils, thick. It is especially preferred, although not mandatory, to apply two coats to the resistor. The coating is cured by heating at elevated temperatures, usually up to about 250C.
The invention will be illustrated by the following nonlimiting examples.
EXAMPLE 1 A coating composition was prepared according to the following recipe:
lsopropanol, Anhydrous A spectographic analysis of each of the components employed in the above composition for their alkali metal content revealed the following percentages by weight expressed in terms of the oxide of each of the alkali metals.
Constituent Li Na K Rb Cs Orthosilicate ND ND ND ND ND Aluminum oxide 0.005 0.03 0.0l ND ND Silicon dioxide 0.001 0.0! 0.0] ND ND Titanium dioxide 0.00l 0.05 0.05 ND ND Bcntonc 27 l.() 0.25 0.l ND ND Pigment 0.0l O. l 5 005 ND ND ND not detected The titanium dioxide added was in a non-cowled form and had a particle-agglomerate size of about 50 microns (325 mesh).
The suspension agent (Bentone 27) was also employed in a non-cowled form and had a particleagglomerate size of about 50 microns (325 mesh).
The coating composition had a pot-life of more than six weeks.
The composition was double-coated on glass-tin oxide film 1K resistors having a 4 watt rated power and cured at 250C. to yield a coating 10 mils thick. The cured coating was found to have a total alkali metal content (as oxides) of approximately 1.02 grams or 0.04 percent. The coated resistors were tested for moisture resistance according to MlL-STD202B Method 106A and found to have an average A R of 1.0 percent.
Upon being subjected to an overload of times rated power, the resistor opened the circuit with no burning or flaming. There was no evidence of external arcing and the coating was found to be non-conductive during overload.
The following example is illustrative of the results achieved employing a coating composition high in alkali metal ion content:
EXAMPLE 2 A coating composition was prepared according to the following recipe:
Component Parts by Weight Aluminum oxide 2l60 Silicon dioxide 540 Titanium dioxide 453 Suspension agent (Bentone 27) Alkyl ammonium montmorollonite 24 Pigment (Cobaltous Alurninate chromic oxide) 225 Pre-Hydrolyzed Tetraethyl Orthosilicate 915 lsopropanol, Anhydrous 204 The components were not selected for low alkali content as in Example 1. The TiO, and suspension agent components were the same as in Example I.
The thus prepared coating composition was coated on resistors identical to that and under the same conditions as in Example 1. The cured coating was found to have an alkali metal content (as oxides) of 10.0 grams or 0.4 percent.
The moisture resistance test indicated an average A R of 3.0 percent, indicating that the increased alkali metal content in the composition deleteriously affected its moisture resistance.
Upon being subjected to an overload of 100 times rated power the coating was found to be conductive and there was evidence of some external arcing, thereby indicating the deleterious effects of high alkali metal content on the dielectric properties of the coating.
The following example is illustrative of the results achieved employing a coating composition containing cowled suspension agent and TiO EXAMPLE 3 A coating composition was prepared according to the following recipe: Component Parts by Weight Aluminum oxide 2160 The particle size of the suspension agent was about 0.] micron while the TiO had an average particle size of about 0.05 micron.
The resulting composition was found to have a potlife of only about 1 week, before it deteriorated into a thick, viscous gel, thereby indicating the deleterious effect of cowled suspension agents and the titanium dioxide on the pot-life of the composition.
Throughout the specification and appended claims, all coating component percentages are by weight based on the total coating composition except as otherwise indicated.
1 claim:
1. An electrical resistor coated with a nonconductive coating composition consisting essentially of a. an at least partially hydrolized tetraalkyl ortho silicate present in an amount of from about to about 55 percent,
b. aluminum oxide present in an amount of at least about 4 percent,
c. titanium dioxide present in an amount of from about I to about 45 percent,
d. silicon dioxide present in an amount of from about 1 to about 48 percent, and
e. a suspension agent present in an amount of from about 0.1 to about 2.0 percent, said percentages being present by weight, wherein said titanium dioxide and said suspension agent are present in the composition as agglomerates greater than about 1 micron in size, and wherein the alkali metal content of said coating composition is such that a cured coating contains less than about 0.05 percent Na, less than about 0.05% K, less than about 0.01% Li, less than about 0.001% Cs, and less than about 0.001% Rb, said percentages of said alkali metals being by weight, based on the total composition, in terms of the oxides of the respective alkali metals.
2. The electrical film resistor of claim 1, said resistor comprising a glass substrate coated with a film of tin oxide.
3. The electrical film resistor of claim 1, wherein said ortho silicate is hydrolized to an extent of from about 10 to about percent.
4. The electrical film resistor of claim 1, wherein said silicon dioxide has a particle size in the range of from about to about 325 mesh.
5. The electrical film resistor of claim 1, wherein said suspension agent is selected from the group consisting of alkyl ammonium montmorillonites, amorphous silica, clays and diatomaceous earth.
6. The electrical film resistor of claim 1, wherein said clay is montmorillonite.
Claims (5)
- 2. The electrical film resistor of claim 1, said resistor comprising a glass substrate coated with a film of tin oxide.
- 3. The electrical film resistor of claim 1, wherein said ortho silicate is hydrolized to an extent of from about 10 to about 90 percent.
- 4. The electrical film resistor of claim 1, wherein said silicon dioxide has a particle size in the range of from about 100 to about 325 mesh.
- 5. The electrical film resistor of claim 1, wherein said suspension agent is selected from the group consisting of alkyl ammonium montmorillonites, amorphous silica, clays and diatomaceous earth.
- 6. The electrical film resistor of claim 1, wherein said clay is montmorillonite.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US72427168A | 1968-04-25 | 1968-04-25 | |
US9419870A | 1970-12-01 | 1970-12-01 |
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US3754989A true US3754989A (en) | 1973-08-28 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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US00094198A Expired - Lifetime US3754989A (en) | 1968-04-25 | 1970-12-01 | Electrical resistor coated with flame-proof coating composition |
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
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US4771095A (en) * | 1986-07-17 | 1988-09-13 | Dynamit Nobel Ag | Aluminum hydroxide filled casting resins on a basis of methacrylic acid esters, and plastic objects and moldings manufactured therefrom |
US5124211A (en) * | 1982-08-02 | 1992-06-23 | Saint-Gobain Vitrage | Distribution of powder for making coated glass |
EP0928009A2 (en) * | 1997-12-26 | 1999-07-07 | Sony Corporation | Resistor, electron gun for cathode-ray tube using the same, and method of manufacturing a resistor |
US6309708B1 (en) * | 1995-09-22 | 2001-10-30 | Daikin Industries, Ltd. | Stain-proofing agent for preventing adherence of stain and composition for paints |
US20050026300A1 (en) * | 2003-07-31 | 2005-02-03 | Agency For Science, Technology And Research | Microfluidics packages and methods of using same |
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US2934736A (en) * | 1957-10-08 | 1960-04-26 | Corning Glass Works | Electrical resistor |
US3134689A (en) * | 1961-03-24 | 1964-05-26 | Intellux Inc | Thin film structure and method of making same |
US3412063A (en) * | 1965-09-07 | 1968-11-19 | Plas Chem Corp | Low temperature cured ceramic coating composition |
US3487349A (en) * | 1967-11-06 | 1969-12-30 | Bell Telephone Labor Inc | Fire retardant composition and elements coated therewith |
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1970
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Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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US2934736A (en) * | 1957-10-08 | 1960-04-26 | Corning Glass Works | Electrical resistor |
US3134689A (en) * | 1961-03-24 | 1964-05-26 | Intellux Inc | Thin film structure and method of making same |
US3412063A (en) * | 1965-09-07 | 1968-11-19 | Plas Chem Corp | Low temperature cured ceramic coating composition |
US3487349A (en) * | 1967-11-06 | 1969-12-30 | Bell Telephone Labor Inc | Fire retardant composition and elements coated therewith |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5124211A (en) * | 1982-08-02 | 1992-06-23 | Saint-Gobain Vitrage | Distribution of powder for making coated glass |
US4771095A (en) * | 1986-07-17 | 1988-09-13 | Dynamit Nobel Ag | Aluminum hydroxide filled casting resins on a basis of methacrylic acid esters, and plastic objects and moldings manufactured therefrom |
US6309708B1 (en) * | 1995-09-22 | 2001-10-30 | Daikin Industries, Ltd. | Stain-proofing agent for preventing adherence of stain and composition for paints |
EP0928009A2 (en) * | 1997-12-26 | 1999-07-07 | Sony Corporation | Resistor, electron gun for cathode-ray tube using the same, and method of manufacturing a resistor |
EP0928009A3 (en) * | 1997-12-26 | 1999-07-21 | Sony Corporation | Resistor, electron gun for cathode-ray tube using the same, and method of manufacturing a resistor |
US6184616B1 (en) | 1997-12-26 | 2001-02-06 | Sony Corporation | Resistor electron gun for cathode-ray tube using the same and method of manufacturing resistor |
US20050026300A1 (en) * | 2003-07-31 | 2005-02-03 | Agency For Science, Technology And Research | Microfluidics packages and methods of using same |
US7357898B2 (en) * | 2003-07-31 | 2008-04-15 | Agency For Science, Technology And Research | Microfluidics packages and methods of using same |
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Owner name: VISHAY INTERTECHNOLOGY, INC., 63 LINCOLN HIGHWAY, Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. SUBJECT TO LICENSE RECITED;ASSIGNOR:CORNING GLASS WORKS;REEL/FRAME:004821/0304 Effective date: 19871110 Owner name: VISHAY INTERTECHNOLOGY, INC.,PENNSYLVANIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CORNING GLASS WORKS;REEL/FRAME:004821/0304 Effective date: 19871110 |