CA1227631A - Capacitor with dielectric comprising polyfunctional acrylate polymer and method of making - Google Patents
Capacitor with dielectric comprising polyfunctional acrylate polymer and method of makingInfo
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- CA1227631A CA1227631A CA000470162A CA470162A CA1227631A CA 1227631 A CA1227631 A CA 1227631A CA 000470162 A CA000470162 A CA 000470162A CA 470162 A CA470162 A CA 470162A CA 1227631 A CA1227631 A CA 1227631A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/018—Dielectrics
- H01G4/06—Solid dielectrics
- H01G4/14—Organic dielectrics
- H01G4/18—Organic dielectrics of synthetic material, e.g. derivatives of cellulose
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- 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
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
- H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
- H01B3/447—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from acrylic compounds
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- 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
- Y10T29/00—Metal working
- Y10T29/43—Electric condenser making
- Y10T29/435—Solid dielectric type
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Abstract
CAPACITOR WITH DIELECTRIC COMPRISING
POLY-FUNCTIONAL ACRYLATE POLYMER AND
METHOD OF MAKING
ABSTRACT OF THE DISCLOSURE
Novel electrical capacitors comprise two electrodes separated by a dielectric member, said dielectric member comprising a polymer of at least one polyfunctional acrylate. The capacitor structure may constitute a single dielectric coating separating two electrode layers, or may comprise a plurality of alternating electrode layers and dielectric coatings.
POLY-FUNCTIONAL ACRYLATE POLYMER AND
METHOD OF MAKING
ABSTRACT OF THE DISCLOSURE
Novel electrical capacitors comprise two electrodes separated by a dielectric member, said dielectric member comprising a polymer of at least one polyfunctional acrylate. The capacitor structure may constitute a single dielectric coating separating two electrode layers, or may comprise a plurality of alternating electrode layers and dielectric coatings.
Description
~L~;2763~
-CAPACITOR WITH DIELECTRIC COMPRISING
POLY-FUNCTIONAL CRUELTY POLYMER END
.
METHOD OF MAKING
This invention relates to electrical capacitors.
More particularly, it relates -to novel capacitors having polyfunctional acrylate polymer dielectrics, and a method for making them The development of electronic devices and circuits of reduced size has led to a need for significantly smaller capacitors having increased capacity per unit volume and high temperature capabilities In particular, such capacitors should be characterized by a low dissipation factor over a wide temperature range in order to conserve energy in the capacitor under operation conditions. Since t however, no single capacitor capable of satisfying the variety of service conditions and requirements was-known or available, a number of - different ones were developed over the years along three main product lines, i.e., the ceramic type, the metallized film type and the electrolytic type. The utility of many of these, however, is limited to somewhat less than the total electronic range up to about 100 micro farads. Moreover, each has other important shortcomings. For example, solid tantalum capacitors of the electrolytic type and ceramic multi layer capacitors typically have a relatively high dissipation factor and it
-CAPACITOR WITH DIELECTRIC COMPRISING
POLY-FUNCTIONAL CRUELTY POLYMER END
.
METHOD OF MAKING
This invention relates to electrical capacitors.
More particularly, it relates -to novel capacitors having polyfunctional acrylate polymer dielectrics, and a method for making them The development of electronic devices and circuits of reduced size has led to a need for significantly smaller capacitors having increased capacity per unit volume and high temperature capabilities In particular, such capacitors should be characterized by a low dissipation factor over a wide temperature range in order to conserve energy in the capacitor under operation conditions. Since t however, no single capacitor capable of satisfying the variety of service conditions and requirements was-known or available, a number of - different ones were developed over the years along three main product lines, i.e., the ceramic type, the metallized film type and the electrolytic type. The utility of many of these, however, is limited to somewhat less than the total electronic range up to about 100 micro farads. Moreover, each has other important shortcomings. For example, solid tantalum capacitors of the electrolytic type and ceramic multi layer capacitors typically have a relatively high dissipation factor and it
- 2 - 36-CA-3559 and also an undesirable failure mode. On the other hand, the metallized film capacitors have very limited volumetric efficiency and totally lack surface mounting capability.
In short, all presently available capacitors are deficient in various respects such as size, long term electronic stability and capability to operate satisfactorily at temperatures in the range of 230-380C.
The evolution of the art has accordingly entailed compromises resulting in general recognition of the need for a better answer to the problem. In this well-developed art, that need is one of relatively long standing.
In Canadian Application Serial No. 464,171, filed September 27, 1984, Skew et at there is disclosed a novel capacitor structure having particularly advantageous properties which make them adaptable to a wide variety of service conditions and requirements. Said structure comprises successive conductive layers which are offset so as to define a central capacitance region of stacked isolated extending layers, a coating of dielectric deposited on each of said layers so that the layers in the capacitance region are substantially spaced and separated by said coating of dielectric, said coating deposition being controlled so as to slope toward cutoff lines spaced substantially from two separated portions of the central capacitor region, said layer deposition extending beyond said cutoff lines so that successive layers fuse into spaced apart terminal portions, and sail cutoff line spacing being sufficient to cause the uppermost dielectric coating of said capacitor to have a horizontal dimension from the capacitor region to the terminal portion to accept a final layer deposition.
A principal object of the present invention, therefore, is to provide novel capacitors having an improved resin dielectrics, and a method for making them.
A further object is to provide such capacitors which are capable of use over a wide range of conditions ~2~76~
In short, all presently available capacitors are deficient in various respects such as size, long term electronic stability and capability to operate satisfactorily at temperatures in the range of 230-380C.
The evolution of the art has accordingly entailed compromises resulting in general recognition of the need for a better answer to the problem. In this well-developed art, that need is one of relatively long standing.
In Canadian Application Serial No. 464,171, filed September 27, 1984, Skew et at there is disclosed a novel capacitor structure having particularly advantageous properties which make them adaptable to a wide variety of service conditions and requirements. Said structure comprises successive conductive layers which are offset so as to define a central capacitance region of stacked isolated extending layers, a coating of dielectric deposited on each of said layers so that the layers in the capacitance region are substantially spaced and separated by said coating of dielectric, said coating deposition being controlled so as to slope toward cutoff lines spaced substantially from two separated portions of the central capacitor region, said layer deposition extending beyond said cutoff lines so that successive layers fuse into spaced apart terminal portions, and sail cutoff line spacing being sufficient to cause the uppermost dielectric coating of said capacitor to have a horizontal dimension from the capacitor region to the terminal portion to accept a final layer deposition.
A principal object of the present invention, therefore, is to provide novel capacitors having an improved resin dielectrics, and a method for making them.
A further object is to provide such capacitors which are capable of use over a wide range of conditions ~2~76~
- 3 - KIWI
A still further object is to provide capacitors in which the dielectric has a low dissipation factor and a relatively low degree of capacitance change over a wide temperature range and a wide variety of operating conditions.
Other objects will in part be obvious and will in part appear hereinafter.
The invention will be described subsequently with reference to the accompanying drawings in which:
Figure 1 is a sectional view of a capacitor in schematic form, depicting a form of the invention, Figures 2 and 3 are graphs of description factor plotted against temperature for different dielectrics, and Figure is an illustrative flow diagram.
In accordance with the foregoing, the present invention includes capacitors comprising two electrodes separated by a dielectric member, said dielectric member comprising a polymer of at least one polyfunctional acrylate having the formula o (I) R (OC-C=CH2)n , wherein:
Al is a hydrocarbon or substituted hydrocarbon radical containing at least 14 carbon atoms;
R2 is hydrogen or an alkyd radical containing 1-5 carbon atoms; and n is from to 6.
The electrodes in the capacitors of this invention may be formed of materials and in configurations known in the art. Typical conductive materials useful as electrodes are aluminum, copper, zinc, tin, stainless steel and alloys thereof, with aluminum being preferred.
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36-C~-3559
A still further object is to provide capacitors in which the dielectric has a low dissipation factor and a relatively low degree of capacitance change over a wide temperature range and a wide variety of operating conditions.
Other objects will in part be obvious and will in part appear hereinafter.
The invention will be described subsequently with reference to the accompanying drawings in which:
Figure 1 is a sectional view of a capacitor in schematic form, depicting a form of the invention, Figures 2 and 3 are graphs of description factor plotted against temperature for different dielectrics, and Figure is an illustrative flow diagram.
In accordance with the foregoing, the present invention includes capacitors comprising two electrodes separated by a dielectric member, said dielectric member comprising a polymer of at least one polyfunctional acrylate having the formula o (I) R (OC-C=CH2)n , wherein:
Al is a hydrocarbon or substituted hydrocarbon radical containing at least 14 carbon atoms;
R2 is hydrogen or an alkyd radical containing 1-5 carbon atoms; and n is from to 6.
The electrodes in the capacitors of this invention may be formed of materials and in configurations known in the art. Typical conductive materials useful as electrodes are aluminum, copper, zinc, tin, stainless steel and alloys thereof, with aluminum being preferred.
.,~
: 3L2~7G~
36-C~-3559
4 --The dielectric members are, as previously noted, polymers of polyfunctional acrylates having formula I.
In that formula, the Al value is a hydrocarbon or substituted hydrocarbon radical containing at least 4 carbon atoms. The types of substituents which are permissible will be apparent to those skilled in the art and generally include substituents having only minor effects on the electrical properties of the molecule.
Illustrative substituents of this type are hydroxy, alkoxy, carbalkoxy and nitrite substituents. Most often however, the Al value is an unsubstituted hydra-carbon radical.
The R value contains at least 4 carbon atoms.
There is no real upper limit to the number of carbon atoms therein, it is within the scope of the invention to use emends of formula I in which Al is a polymeric radical containing, for example, as many as 500 and preferably up to about 300 carbon atoms.
The Al radical may contain aliphatic t alcoholic or aromatic moieties or a mixture thereof. Preferably, however, all moieties present therein are aliphatie, allele or both.
The R value, as previously noted, may be hydrogen or an alkyd radical containing 1-5 carbon atoms Most often, R2 is hydrogen or methyl and especially hydrogen.
Thus, the term aerylate" as used herein embraces both aerylates and a-substituted aerylates including methacrylates and the like, although the acrylates (i.e.
the compounds in which R is hydrogen are usually preferred The value of n may be from 2 to 6, and is most often 2 or 3.
From the foregoing, it will be apparent that the compounds of formula I may typically be prepared by esterification of acrylic acid, methaerylic acid or the like, or functional derivatives thereof such as the acid I
CASEY
In that formula, the Al value is a hydrocarbon or substituted hydrocarbon radical containing at least 4 carbon atoms. The types of substituents which are permissible will be apparent to those skilled in the art and generally include substituents having only minor effects on the electrical properties of the molecule.
Illustrative substituents of this type are hydroxy, alkoxy, carbalkoxy and nitrite substituents. Most often however, the Al value is an unsubstituted hydra-carbon radical.
The R value contains at least 4 carbon atoms.
There is no real upper limit to the number of carbon atoms therein, it is within the scope of the invention to use emends of formula I in which Al is a polymeric radical containing, for example, as many as 500 and preferably up to about 300 carbon atoms.
The Al radical may contain aliphatic t alcoholic or aromatic moieties or a mixture thereof. Preferably, however, all moieties present therein are aliphatie, allele or both.
The R value, as previously noted, may be hydrogen or an alkyd radical containing 1-5 carbon atoms Most often, R2 is hydrogen or methyl and especially hydrogen.
Thus, the term aerylate" as used herein embraces both aerylates and a-substituted aerylates including methacrylates and the like, although the acrylates (i.e.
the compounds in which R is hydrogen are usually preferred The value of n may be from 2 to 6, and is most often 2 or 3.
From the foregoing, it will be apparent that the compounds of formula I may typically be prepared by esterification of acrylic acid, methaerylic acid or the like, or functional derivatives thereof such as the acid I
CASEY
- 5 --chlorides, androids and lower alkyd esters, with a wide variety of compounds containing the R valuer Illustrative compounds of this type are polyhydroxy compounds and polyepoxides~ Particularly useful polyfunctional acrylates of formula I are the following:
Acrylates of aliphatic polyhydroxy compounds containing about ~-20 carbon atoms, illustrated by neopentyl glycol, trimethylolpropane, 1, 6-hexanediol and a, widely mixtures having an average chain length of 12-20 carbon atoms.
Acrylates of polymers having groups capable of reacting with acrylic acid or derivatives thereof Illustrative are various hydroxy~terminated dine polymers such as polybutadiene, typically having a number average molecular weight within the range of about 1000-5000~
Acrylates of aromatic diepoxides and polyepoxides, illustrated by diepoxy derivatives of 2,2-bis(~-hydroxy-phenyl)propane or "bisphenol A".
A number of commercially available polyfunctional acrylates are useful for the preparation of dielectrics in the capacitors of this invention Among them are the following, many of which are identified by trademarks as indicated:
Trimethylolpropane triacrylate.
Neopentyl glycol diacrylate.
sisphenol A diacrylate~ `
Sullenness "Salaried 3700", a diacrylate of a diepoxide derived from his phenol A.
"Sartomer SR-349", a diacrylate of ethoxylated bisphenol A.
Sartomer 'tChemlink 2000", a diacrylate of an a, w-alkanediol containing an average of 1~~15 carbon atoms ~2~7~3~ 36-CA-3559 A diacrylate of Argo "Posy by", which is a hydroxy-terminated butadiene resin having a number average molecular weight of about 3000.
While i-t is within the scope of the invention to use a single polyfunctional compound in forming the dielectric, it is often preferred to employ copolymers prepared from blends of two or more such compounds This may result in lower dissipation faction than is the case for most polyfunctional acrylates used alone. It may also optimize the physical properties of the material, e.g., lower the viscosity of the monomer composition to facilitate its deposition It is also within the scope of the invention to use copolymers prepared from mixtures of at least one compound of formula I with at least one monoacrylate of the formula O
(II) R OC-C=CH2 wherein R2 is as previously defined and R3 is a hydra-carbon or substituted hydrocarbon radical, typically containing about 4-25 carbon atoms. Illustrative moo-acrylates of formula II are cyclohexyl methacrylate and various acrylated derivatives of fatty acids containing such substituents as carbomethoxy or nitrite. Typical copolymers of compounds of formulas I and II contain about 10-50~ by weight, most often about 15-35~, of compounds of formula II with the balance being compounds of formula I.
With respect to these commercially available acrylates and the like, it's frequently preferred to remove residual acrylic acid and other ionic compounds 7~3~L
and impurities which may be present in the materials as received prom the supplier. Such impurities are readily removed by known methods such as the use of absorption columns or ion exchange resins.
Illustrative polyfunctional acrylate compositions whose polymers are suitable as dielectrics in the capacitors of this invention are illustrated in Tables I and II. All percentages in these tables are by volume.
TABLE I
Ingredient Example 1 2 3 'I'Poly by" diacrylate 100 50 ---~'Chemlink 2000" --- 50 100 TABLE II
ingredient Example 4 5 6 7 3 9 10 11 Trimethylol- 50 100 -- -- -- 25 ]?rPane in-acrylate Neopentyl -- -- 50 60 40 4050 25 luckily diacrylate Bisphenol A -- -- -- -- -- 20 -- --,~iacrylate "Sartomer SR-349" -- -- 50 20 -- -- -- --"Salaried 3700" 50 -- -- 20 50 40 50 50 Cyclohexyl -- -- -- -- 10 --methacrylate A preferred subgenus of the capacitors of this invention is disclosed and claimed in United States Patent No. 4,490,774, issued December 25, I
3.-1 ~2~3~
KIWI
dielectric member in those capacitors is a polymer ox at least one polyfunctional acrylate of formula I in which R2 is hydrogen or methyl, n is from 2 to 4, and Al is an aliphatic, alicyclic or mixed aliphatic-alicyclic radical having about 10-40 carbon atoms which optionally contains up to about three olefinic linkages, said olefinic linkages being non-conjugated.
The Al radical in this preferred subgenus may be aliphatic, alycyclic or mixed aliphatic-alicyclic; it - 10 may optionally contain up to about three olefinic linkages which are non-conjugated, and contains about 10-40 carbon atoms. Suitable polyhydroxy compounds include straight chain compounds such as hexadecanediol and octadecanediol, with the hydroxy groups being located anywhere on the chain, and branched chain isomers thereof. sty branched chain" is meant that at least one carbon atom is present in a branch. Thus, configurations such as H t H2)15 CH3(CH2~6CH(CH2)6OH
OH
are unbranched, while 3(CH2~6CIH(CH2)6CH2OH and SHEA
WHOOSH (SHEA) 6fH(CH2) SUE
SHEA SHEA
are branched.
~2~7~3~L
KIWI
_ g A first preferred class of polyhydroxy compounds within this subgenus consists of -those characterized by being branched and also by having at least 18 carbon atoms in a single chain; that is, at least 18 carbon atoms are successively bonded without branching Particularly suitable polyfunctional acrylates derived therefrom are those having the formulas (III) CH3(CH2)rCH(CH2)sCH20C-CH=CH2 and o CH201C~CH=CH
(IV) Cheshire ~_(cH2)scH2oc-cH C~2 CH20C-CH=CH2 wherein r and s are each 7 or 8 and theism of r and s is 15. They may be obtained, for example by acrylic acid esterification of the hydroformylation products of oleic acid as disclosed in US. Patent 4,2~3,818. Another suitable compound is 1,12-octadecanediol diacrylate, formed by hydrogenolysis of ricinoleic acid followed by esterification.
Also within this first preferred class of polyhydroxy compounds are single compounds and mixtures, usually mixtures, in which Al is at least one aliphatic or alicyclic radical containing about 20-40 carbon atoms and optionally up to about three non-conjugated olefinic linkages. At least about 40%, and preferably at least about 50%, of the total number of Al radicals therein are alicyclic. Thus, the polyhydroxy compounds may be entirely alicyclic or may be mixtures of cyclic and alicyclic compounds satisfying these percentage limitations. Acrylates prepared from such polyhydroxy compounds, and their polymers, are disclosed and claimed in United States Patent No. 4,515,931, issued May 7, 1985 to Olson et at.
It is frequently convenient to prepare such polyhydroxy compounds by reduction of at least one corresponding polycarboxylic acid or ester thereof, which may be saturated or may contain olefinic linkages. A typical suitable polycarboxylic acid is linoleic acid diver (hereinafter "diver acid"), a mixture consisting essentially of cyclic, moo-cyclic and by cyclic dicarboxylic acids which typically contain up to two olefinic bonds per molecule. A particularly suitable diver acid is sold by Emery Industries under the trade mark "Employ 1010". According to Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition, Volume 7, pp. 768-770, the following are structures of typical molecular species present in the methyl ester of diver acid:
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763~
(V) CH3(C~2)7CH(CH2)8COOCH3 CH3(CH2~7~=CH(CH2)7COOCH3 (VI) OH CH(CH2)7COOCH3 C~3~C~l2)s~ (C~12)7Cooc~3`
Chocolate (VII) (1 2)7 SHEA
(C~12)7cOocH3 lo CH3(C112)3C~7=CH X J
C113(CH2)3 Thus, free diver acid obviously comprises free dicarboxylic acids having corresponding structures.
The esters of formula V, VI and VII, their corresponding free acids, and similar polvc~rho~vlic acids and esters may be reduced by known methods, such as by hydrogen in the presence of a hydrogenation catalyst or by lithium aluminum hydrides to produce dills useful for preparation of the polyfunctional acrylates. Depending on the method of reduction of these or similar acids or esters, the reduction product may be saturated or may contain olefinic linkages. For example, lithium aluminum hydrides reduction normally will not affect olefinic linkages while some hydrogenation methods (e.g., in the presence of a palladium catalyst) Jill reduce them to saturated linkages. Thus, reduction of compounds V, VI and YIP may produce dills of the ~2~7 Eye 36-C~ 3559 respective formulas (VIII)CH3(CH2)71~l(C~2)8cH2 CH3(CH2~7 -~HtCH2)7CH2 H
Ho [Hi (IX)~H _CH(cH2)7cH20H
Shekel (Cll2)7c~l20H
C~3(C~l2) (X)( 2)7 Ho (cliche ill] [Hi C~3(C~l2)3CH SUE
CH3(CH2) I
wherein tile broken lines and hydrogen atoms in brackets indicate that the corresponding carbon carbon bonds may be single or double bonds depending on the method of reduction. It is frequently found that the compounds which contain only single bonds have properties somewhat more favorable than those of the analogous double-bonded compounds. Suitable dill mixtures of this type are commercially available from Henkel Corporation under the trade- "Demurral".
Other suitable polyhydroxy compounds within this first preferred class may be prepared by reduction of various acrylic acid-unsaturated fatty acid condensation products. These polyhydroxy compounds may be illustrated by the formula 763~
13 - 36-C~-3559 I\
(XI) CF13(CH2)m - (Sheepish wherein m may be, for example, from 3 to 5, p may be from 7 to 9 and the sum of m and p is 12. A typical commercially available dicarboxylic acid which may be reduced to a dill of formula XI is sold under the trade mark "Westvaco 1550 Dozed"; it has the formula (XII) C~3(CH2)5 (SCHICK
COO
and is an adduce of linoleic and acrylic acids. It is also described in Kirk-Othmer, op. cit., at p. 779.
A second preferred class of polyhydxoxy compounds consists of 1,2-alkanediols in which Al has the formula wherein R4 is an alkyd radical containing about 8-28 carbon atoms. Acrylates of such 1,2-alkanediols, and polymers thereof, are disclosed and claimed in U.S.
Patent No. 4,533,710, issued August 6, 1986 to Olson et at.
Examples of suitable R4 radicals are l-octyl, 2-methylheptyl, l-nonyl, 2,3-dimethylheptyl, l-decyl, 2-dodecyl, l-tetradecyl, l-octadecyl, l-eicosyl and l-docosyl. Radicals having the formula R5CH2, wherein R5 is an alkyd and especially a straight chain alkyd radical having about 7-27 and most often about 9-17 carbon atoms, are preferred as R .
Procedures for acrylic or methacrylic acid l~Z~631 esterification of the above-describecl polyhydroxy compounds will be apparent to one skilled in the art.
Thus, the acid and alcohol may typically be reacted in a suitable solvent, in the presence of a small amount of an acidic esterification catalyst such as sulfuric acid, p-toluenesulfonic acid, acidic ion exchange resins or acidified clays. Ordinarily, a stoichiometric excess of the acid is used, the ratio of equivalents of acid to dill typically being between about 2:1 and about 4:1.
The reaction is ordinarily carried out at about 100-200C, most often about lQ0-150C. It is often preferred to incorporate in the esterification mixture a minor amount of a polymerization inhibitor such as p-methoxyphenol, 2,6-di-t-butylphenol or 2,4,6-tri-t-butylphenol. The acrylic or methacrylic acid may be replaced by a functional derivative thereof such as an azalea halide, lower alkyd ester or aside, with suitable modification of the reaction conditions.
The preparation of the polyfunctional acrylates of the above-described preferred subgenus is illustrated by the following examples.
A mixture of 102 parts by weight (0.34 mole) of a commercially available (from Honeywell Corporation) dill having the formula CH3(CH2)rCH((CH2)sCH2OH
SHEA
in which the sum of r and s is 15, 2~55 parts of p-methoxyphenol and 2.38 parts of p-toluenesulfonic acid in 153 parts of Nixon was heated to reflex with stirring and 5.44 parts (0.76 mole) of acrylic acid was added over several hours. Heating was continued as ~'7~i31 36-C~-3559 water was removed by azeotropic distillation. When the theoretical amount of water had been removed, the solution was diluted with 206 parts of Nixon and extracted five times with a I (by weight) aqueous potassium hydroxide solution and twice with aqueous sodium chloride solution. Upon evaporation of the hexane, there was obtained 127 parts (92% of theoretical) of the diacrylate which was filtered through glass fibers and stabilized by the addition of 100 ppm of p-methoxyphenol.
A mixture of 100 grams (0.3 mole) of a com~ercially-available (from Henkel Corporation) trio having the formula SHEA
CH3(CH2)rl-(CH2)SCH2OH
SHEA
in which the sum of r and s is 15, 0.3 gram of p-methoxyphenol and 2 grams of p-toluenesulfonic acid in 500 ml. ox Tulane was heated to 120C and 115 ml.
(1.64 moles) of acrylic acid was added drops. Heating was continued as water was removed by azeotropic distillation. When the theoretical amount of water had been removed t the solution was washed with aqueous potassium carbonate solution and dried. The desired triacrylate was obtained as a liquid upon evaporation of solvent.
Following a procedure similar to that of Example 13, 1,12-octadecanediol diacrylate was prepared.
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EXAM LOWE
To a solution of 96 grams (2.5 moles) of lithium aluminum hydrides in 3000 ml. of tetrahydrofuran was added drops, with stirring, kiwi grams (0.7I mole) of imply 1010" diver acid. The mixture was heated under reflex for about 40 hours and then neutralized by the sequential addition of 96 ml. of water, 96 ml. of 15 percent aqueous sodium hydroxide solution, and 288 ml.
of water. The neutralized mixture was filtered and the solvent was evaporated prom the filtrate to yield the desired dill.
A solution of 200 grams (0.37 mole) of the dill, 157 ml. (2.24 moles) of acrylic acid, 3 grams of p-toluenesulfonic acid and 0.5 gram of p-methoxyphenol in 1000 ml. of Tulane was heated under reflex as water was removed by azeotropic distillation. when the stoichiometric amount of water (about 13.3 ml.) had been removed, the solution was cooled, filtered and washed several times with dilute potassium carbonate solution and once with dilute sodium chloride solution. It was then dried over magnesium sulfate and the solvent was evaporated to afford the desired diacrylate as a liquid.
Following the procedure of Example 15, "Westvaco 1550 Dozed" was reduced by lithium aluminum hydrides in tetrahydrofuran to a dill having formula VIII in which m is 5, p is 7 and the broken line indicates a double bond. This dill (85 grams, 0.25 mole) was reacted with acrylic acid (90 ml., 1~28 mole) in Tulane solution to 0 yield the desired diacrylate as a liquid.
Following a procedure similar to that of Example 13, a liquid diacrylate was prepared from a commercially available dill which was in turn prepared by hydrogenation of a methyl ester of linoleic acid diver, and whose 763~
36-C~-3559 principal components have formulas VIII, IX and X
wherein the broken lines represent predominantly single bonds.
AMPULE
A solution of 51 grams (0020 mole) of 1,2-hexadecanediol, 100 ml. (1.5 moles) of acrylic acid, 1~5 grams of p-toluenesulfonic acid and 2 grams of p-methoxyphenol in 400 grams of Tulane was heated for about 24 hours under reflex as water was removed by azeotropic distillation. The solution was cooled, filtered and washed several times with dilute potassium carbonate solution and once with dilute sodium chloride solution. It was then dried and the solvent was evaporated to afford the desired 1,2-hexadecanediol diacrylate as a liquid.
The polyfunctional acrylates may be polymerized under free-radical'conditions, either alone or in the presence of other monomers The term "polymer," as used herein, includes addition homopolymers and copolymers with one or more other monomers.
Polymerization by the free-radical method may be effected in bulk, solution, suspension or emulsion, by contacting the monomer or monomers with a polymerization initiator either in the absence or presence of a delineate at a temperature of about 0-200C Suitable initiators include bouncily peroxide, tertiary bottle hydroperoxide, acutely peroxide hydrogen peroxide, asobisisobutyronitrile, persulfate-bisulfite, persulfate~sodium formaldehyde sulfoxylate, chlorate-sulfite and the like.
Alternatively, polymerization may be effected by irradiation techniques, as by ultraviolet electron beam or plasma irradiation. The polymers thus obtained are generally cross linked, as a result of the polyp functionality of the acrylates.
Referring now to Figure l, there is shown in Sue schematic form a capacitor comprising lower electrode 10 which may be aluminum foil, a dielectric coating 11 of a polyfunctional acrylate polymer which may be formed by deposition of one of the above described acrylate compositions on the surface of electrode 10 by, for example, vacuum evaporation or roller coating and suitable polymerization, and upper electrode 12 which is a thin metallized layer of aluminum deposited on dielectric film 11. Leads 13 and 14 are respectively attached to lower and upper electrodes 10 and 12.
Another aspect of the present invention to a method of making a capacitor, said method comprising the steps of forming on a substrate a dielectric coating of a polymer of at least one polyEunctional acrylate as previously described and depositing an electrode layer on said dielectric coating. The coating may be produced by applying the polymer, optionally in solution in a substantially inert solvent, by conventional means such as flowing, spraying dipping, brushing, roller coating, spin coating, drawing down or the like, followed by evaporation of any solvent used. It is usually preferred, however, to apply a polyfunctional acrylate monomer film and subsequently polymerize it by one of the methods previously described. The use of electron beam polymerization is particularly preferred since such a process very rapidly polymerizes the monomer composition without the need for additional curing agents, and thus leads to economical production of very thin coatings In one embodiment of the method of this invention, the substrate is itself a conductive material which may serve as an electrode whereupon the two electrodes and the dielectric coating separating them may constitute the entire capacitor. Figure 4 of the drawing is an illustrative flow diagram of this embodiment which is also illustrated by the following example.
~2;2~3~
Uniform prototype capacitors were produced by drawing down layers of the compositions of Examples 1-11 on an aluminum foil substrate, polymerizing said monomer layer by contact with an electron beam, and depositing a metallic aluminum layer thereon. The thickness of the aluminum foil electrode was 12.5 microns, that of the dielectric layer was 3-6 microns and that of the deposited aluminum electrode was 300-500 Angstroms (0.03-0.05 micron). The areas of the prototype capacitors were about 1 square inch. The dissipation factors of said capacitors were measured at 60 Ho. using an AC bridge.
Figures 2 and 3 graphically depict the relationship between temperature and dissipation factor for typical prototype capacitors prepared as described above in which the polyfunctional acrylate compositions of Examples 1 and 2, respectively, were respectively polymerized by 15- and 10-megarad electron beams to form the dielectric coatings. As is apparent, the dissipation factors remained well below 0.3% from 30 to 130C.
Table III lists the dissipation factors at various temperatures of other typical capacitors made as described above, using the previously described polyfunctional acrylate compositions.
j . ____ ..... _ _ ... I_ .
763~
TABLE III
Electron Dissipation factor, %
beam, Examplemagarads 30C 100C 120C__125C 165C
3 15 1.55 --- 0.25 - - ---4 10 1.05 --- 0.95 --- ------ ox ___ ___ ___
Acrylates of aliphatic polyhydroxy compounds containing about ~-20 carbon atoms, illustrated by neopentyl glycol, trimethylolpropane, 1, 6-hexanediol and a, widely mixtures having an average chain length of 12-20 carbon atoms.
Acrylates of polymers having groups capable of reacting with acrylic acid or derivatives thereof Illustrative are various hydroxy~terminated dine polymers such as polybutadiene, typically having a number average molecular weight within the range of about 1000-5000~
Acrylates of aromatic diepoxides and polyepoxides, illustrated by diepoxy derivatives of 2,2-bis(~-hydroxy-phenyl)propane or "bisphenol A".
A number of commercially available polyfunctional acrylates are useful for the preparation of dielectrics in the capacitors of this invention Among them are the following, many of which are identified by trademarks as indicated:
Trimethylolpropane triacrylate.
Neopentyl glycol diacrylate.
sisphenol A diacrylate~ `
Sullenness "Salaried 3700", a diacrylate of a diepoxide derived from his phenol A.
"Sartomer SR-349", a diacrylate of ethoxylated bisphenol A.
Sartomer 'tChemlink 2000", a diacrylate of an a, w-alkanediol containing an average of 1~~15 carbon atoms ~2~7~3~ 36-CA-3559 A diacrylate of Argo "Posy by", which is a hydroxy-terminated butadiene resin having a number average molecular weight of about 3000.
While i-t is within the scope of the invention to use a single polyfunctional compound in forming the dielectric, it is often preferred to employ copolymers prepared from blends of two or more such compounds This may result in lower dissipation faction than is the case for most polyfunctional acrylates used alone. It may also optimize the physical properties of the material, e.g., lower the viscosity of the monomer composition to facilitate its deposition It is also within the scope of the invention to use copolymers prepared from mixtures of at least one compound of formula I with at least one monoacrylate of the formula O
(II) R OC-C=CH2 wherein R2 is as previously defined and R3 is a hydra-carbon or substituted hydrocarbon radical, typically containing about 4-25 carbon atoms. Illustrative moo-acrylates of formula II are cyclohexyl methacrylate and various acrylated derivatives of fatty acids containing such substituents as carbomethoxy or nitrite. Typical copolymers of compounds of formulas I and II contain about 10-50~ by weight, most often about 15-35~, of compounds of formula II with the balance being compounds of formula I.
With respect to these commercially available acrylates and the like, it's frequently preferred to remove residual acrylic acid and other ionic compounds 7~3~L
and impurities which may be present in the materials as received prom the supplier. Such impurities are readily removed by known methods such as the use of absorption columns or ion exchange resins.
Illustrative polyfunctional acrylate compositions whose polymers are suitable as dielectrics in the capacitors of this invention are illustrated in Tables I and II. All percentages in these tables are by volume.
TABLE I
Ingredient Example 1 2 3 'I'Poly by" diacrylate 100 50 ---~'Chemlink 2000" --- 50 100 TABLE II
ingredient Example 4 5 6 7 3 9 10 11 Trimethylol- 50 100 -- -- -- 25 ]?rPane in-acrylate Neopentyl -- -- 50 60 40 4050 25 luckily diacrylate Bisphenol A -- -- -- -- -- 20 -- --,~iacrylate "Sartomer SR-349" -- -- 50 20 -- -- -- --"Salaried 3700" 50 -- -- 20 50 40 50 50 Cyclohexyl -- -- -- -- 10 --methacrylate A preferred subgenus of the capacitors of this invention is disclosed and claimed in United States Patent No. 4,490,774, issued December 25, I
3.-1 ~2~3~
KIWI
dielectric member in those capacitors is a polymer ox at least one polyfunctional acrylate of formula I in which R2 is hydrogen or methyl, n is from 2 to 4, and Al is an aliphatic, alicyclic or mixed aliphatic-alicyclic radical having about 10-40 carbon atoms which optionally contains up to about three olefinic linkages, said olefinic linkages being non-conjugated.
The Al radical in this preferred subgenus may be aliphatic, alycyclic or mixed aliphatic-alicyclic; it - 10 may optionally contain up to about three olefinic linkages which are non-conjugated, and contains about 10-40 carbon atoms. Suitable polyhydroxy compounds include straight chain compounds such as hexadecanediol and octadecanediol, with the hydroxy groups being located anywhere on the chain, and branched chain isomers thereof. sty branched chain" is meant that at least one carbon atom is present in a branch. Thus, configurations such as H t H2)15 CH3(CH2~6CH(CH2)6OH
OH
are unbranched, while 3(CH2~6CIH(CH2)6CH2OH and SHEA
WHOOSH (SHEA) 6fH(CH2) SUE
SHEA SHEA
are branched.
~2~7~3~L
KIWI
_ g A first preferred class of polyhydroxy compounds within this subgenus consists of -those characterized by being branched and also by having at least 18 carbon atoms in a single chain; that is, at least 18 carbon atoms are successively bonded without branching Particularly suitable polyfunctional acrylates derived therefrom are those having the formulas (III) CH3(CH2)rCH(CH2)sCH20C-CH=CH2 and o CH201C~CH=CH
(IV) Cheshire ~_(cH2)scH2oc-cH C~2 CH20C-CH=CH2 wherein r and s are each 7 or 8 and theism of r and s is 15. They may be obtained, for example by acrylic acid esterification of the hydroformylation products of oleic acid as disclosed in US. Patent 4,2~3,818. Another suitable compound is 1,12-octadecanediol diacrylate, formed by hydrogenolysis of ricinoleic acid followed by esterification.
Also within this first preferred class of polyhydroxy compounds are single compounds and mixtures, usually mixtures, in which Al is at least one aliphatic or alicyclic radical containing about 20-40 carbon atoms and optionally up to about three non-conjugated olefinic linkages. At least about 40%, and preferably at least about 50%, of the total number of Al radicals therein are alicyclic. Thus, the polyhydroxy compounds may be entirely alicyclic or may be mixtures of cyclic and alicyclic compounds satisfying these percentage limitations. Acrylates prepared from such polyhydroxy compounds, and their polymers, are disclosed and claimed in United States Patent No. 4,515,931, issued May 7, 1985 to Olson et at.
It is frequently convenient to prepare such polyhydroxy compounds by reduction of at least one corresponding polycarboxylic acid or ester thereof, which may be saturated or may contain olefinic linkages. A typical suitable polycarboxylic acid is linoleic acid diver (hereinafter "diver acid"), a mixture consisting essentially of cyclic, moo-cyclic and by cyclic dicarboxylic acids which typically contain up to two olefinic bonds per molecule. A particularly suitable diver acid is sold by Emery Industries under the trade mark "Employ 1010". According to Kirk-Othmer, Encyclopedia of Chemical Technology, Third Edition, Volume 7, pp. 768-770, the following are structures of typical molecular species present in the methyl ester of diver acid:
.,, I
763~
(V) CH3(C~2)7CH(CH2)8COOCH3 CH3(CH2~7~=CH(CH2)7COOCH3 (VI) OH CH(CH2)7COOCH3 C~3~C~l2)s~ (C~12)7Cooc~3`
Chocolate (VII) (1 2)7 SHEA
(C~12)7cOocH3 lo CH3(C112)3C~7=CH X J
C113(CH2)3 Thus, free diver acid obviously comprises free dicarboxylic acids having corresponding structures.
The esters of formula V, VI and VII, their corresponding free acids, and similar polvc~rho~vlic acids and esters may be reduced by known methods, such as by hydrogen in the presence of a hydrogenation catalyst or by lithium aluminum hydrides to produce dills useful for preparation of the polyfunctional acrylates. Depending on the method of reduction of these or similar acids or esters, the reduction product may be saturated or may contain olefinic linkages. For example, lithium aluminum hydrides reduction normally will not affect olefinic linkages while some hydrogenation methods (e.g., in the presence of a palladium catalyst) Jill reduce them to saturated linkages. Thus, reduction of compounds V, VI and YIP may produce dills of the ~2~7 Eye 36-C~ 3559 respective formulas (VIII)CH3(CH2)71~l(C~2)8cH2 CH3(CH2~7 -~HtCH2)7CH2 H
Ho [Hi (IX)~H _CH(cH2)7cH20H
Shekel (Cll2)7c~l20H
C~3(C~l2) (X)( 2)7 Ho (cliche ill] [Hi C~3(C~l2)3CH SUE
CH3(CH2) I
wherein tile broken lines and hydrogen atoms in brackets indicate that the corresponding carbon carbon bonds may be single or double bonds depending on the method of reduction. It is frequently found that the compounds which contain only single bonds have properties somewhat more favorable than those of the analogous double-bonded compounds. Suitable dill mixtures of this type are commercially available from Henkel Corporation under the trade- "Demurral".
Other suitable polyhydroxy compounds within this first preferred class may be prepared by reduction of various acrylic acid-unsaturated fatty acid condensation products. These polyhydroxy compounds may be illustrated by the formula 763~
13 - 36-C~-3559 I\
(XI) CF13(CH2)m - (Sheepish wherein m may be, for example, from 3 to 5, p may be from 7 to 9 and the sum of m and p is 12. A typical commercially available dicarboxylic acid which may be reduced to a dill of formula XI is sold under the trade mark "Westvaco 1550 Dozed"; it has the formula (XII) C~3(CH2)5 (SCHICK
COO
and is an adduce of linoleic and acrylic acids. It is also described in Kirk-Othmer, op. cit., at p. 779.
A second preferred class of polyhydxoxy compounds consists of 1,2-alkanediols in which Al has the formula wherein R4 is an alkyd radical containing about 8-28 carbon atoms. Acrylates of such 1,2-alkanediols, and polymers thereof, are disclosed and claimed in U.S.
Patent No. 4,533,710, issued August 6, 1986 to Olson et at.
Examples of suitable R4 radicals are l-octyl, 2-methylheptyl, l-nonyl, 2,3-dimethylheptyl, l-decyl, 2-dodecyl, l-tetradecyl, l-octadecyl, l-eicosyl and l-docosyl. Radicals having the formula R5CH2, wherein R5 is an alkyd and especially a straight chain alkyd radical having about 7-27 and most often about 9-17 carbon atoms, are preferred as R .
Procedures for acrylic or methacrylic acid l~Z~631 esterification of the above-describecl polyhydroxy compounds will be apparent to one skilled in the art.
Thus, the acid and alcohol may typically be reacted in a suitable solvent, in the presence of a small amount of an acidic esterification catalyst such as sulfuric acid, p-toluenesulfonic acid, acidic ion exchange resins or acidified clays. Ordinarily, a stoichiometric excess of the acid is used, the ratio of equivalents of acid to dill typically being between about 2:1 and about 4:1.
The reaction is ordinarily carried out at about 100-200C, most often about lQ0-150C. It is often preferred to incorporate in the esterification mixture a minor amount of a polymerization inhibitor such as p-methoxyphenol, 2,6-di-t-butylphenol or 2,4,6-tri-t-butylphenol. The acrylic or methacrylic acid may be replaced by a functional derivative thereof such as an azalea halide, lower alkyd ester or aside, with suitable modification of the reaction conditions.
The preparation of the polyfunctional acrylates of the above-described preferred subgenus is illustrated by the following examples.
A mixture of 102 parts by weight (0.34 mole) of a commercially available (from Honeywell Corporation) dill having the formula CH3(CH2)rCH((CH2)sCH2OH
SHEA
in which the sum of r and s is 15, 2~55 parts of p-methoxyphenol and 2.38 parts of p-toluenesulfonic acid in 153 parts of Nixon was heated to reflex with stirring and 5.44 parts (0.76 mole) of acrylic acid was added over several hours. Heating was continued as ~'7~i31 36-C~-3559 water was removed by azeotropic distillation. When the theoretical amount of water had been removed, the solution was diluted with 206 parts of Nixon and extracted five times with a I (by weight) aqueous potassium hydroxide solution and twice with aqueous sodium chloride solution. Upon evaporation of the hexane, there was obtained 127 parts (92% of theoretical) of the diacrylate which was filtered through glass fibers and stabilized by the addition of 100 ppm of p-methoxyphenol.
A mixture of 100 grams (0.3 mole) of a com~ercially-available (from Henkel Corporation) trio having the formula SHEA
CH3(CH2)rl-(CH2)SCH2OH
SHEA
in which the sum of r and s is 15, 0.3 gram of p-methoxyphenol and 2 grams of p-toluenesulfonic acid in 500 ml. ox Tulane was heated to 120C and 115 ml.
(1.64 moles) of acrylic acid was added drops. Heating was continued as water was removed by azeotropic distillation. When the theoretical amount of water had been removed t the solution was washed with aqueous potassium carbonate solution and dried. The desired triacrylate was obtained as a liquid upon evaporation of solvent.
Following a procedure similar to that of Example 13, 1,12-octadecanediol diacrylate was prepared.
~l2;~763~
EXAM LOWE
To a solution of 96 grams (2.5 moles) of lithium aluminum hydrides in 3000 ml. of tetrahydrofuran was added drops, with stirring, kiwi grams (0.7I mole) of imply 1010" diver acid. The mixture was heated under reflex for about 40 hours and then neutralized by the sequential addition of 96 ml. of water, 96 ml. of 15 percent aqueous sodium hydroxide solution, and 288 ml.
of water. The neutralized mixture was filtered and the solvent was evaporated prom the filtrate to yield the desired dill.
A solution of 200 grams (0.37 mole) of the dill, 157 ml. (2.24 moles) of acrylic acid, 3 grams of p-toluenesulfonic acid and 0.5 gram of p-methoxyphenol in 1000 ml. of Tulane was heated under reflex as water was removed by azeotropic distillation. when the stoichiometric amount of water (about 13.3 ml.) had been removed, the solution was cooled, filtered and washed several times with dilute potassium carbonate solution and once with dilute sodium chloride solution. It was then dried over magnesium sulfate and the solvent was evaporated to afford the desired diacrylate as a liquid.
Following the procedure of Example 15, "Westvaco 1550 Dozed" was reduced by lithium aluminum hydrides in tetrahydrofuran to a dill having formula VIII in which m is 5, p is 7 and the broken line indicates a double bond. This dill (85 grams, 0.25 mole) was reacted with acrylic acid (90 ml., 1~28 mole) in Tulane solution to 0 yield the desired diacrylate as a liquid.
Following a procedure similar to that of Example 13, a liquid diacrylate was prepared from a commercially available dill which was in turn prepared by hydrogenation of a methyl ester of linoleic acid diver, and whose 763~
36-C~-3559 principal components have formulas VIII, IX and X
wherein the broken lines represent predominantly single bonds.
AMPULE
A solution of 51 grams (0020 mole) of 1,2-hexadecanediol, 100 ml. (1.5 moles) of acrylic acid, 1~5 grams of p-toluenesulfonic acid and 2 grams of p-methoxyphenol in 400 grams of Tulane was heated for about 24 hours under reflex as water was removed by azeotropic distillation. The solution was cooled, filtered and washed several times with dilute potassium carbonate solution and once with dilute sodium chloride solution. It was then dried and the solvent was evaporated to afford the desired 1,2-hexadecanediol diacrylate as a liquid.
The polyfunctional acrylates may be polymerized under free-radical'conditions, either alone or in the presence of other monomers The term "polymer," as used herein, includes addition homopolymers and copolymers with one or more other monomers.
Polymerization by the free-radical method may be effected in bulk, solution, suspension or emulsion, by contacting the monomer or monomers with a polymerization initiator either in the absence or presence of a delineate at a temperature of about 0-200C Suitable initiators include bouncily peroxide, tertiary bottle hydroperoxide, acutely peroxide hydrogen peroxide, asobisisobutyronitrile, persulfate-bisulfite, persulfate~sodium formaldehyde sulfoxylate, chlorate-sulfite and the like.
Alternatively, polymerization may be effected by irradiation techniques, as by ultraviolet electron beam or plasma irradiation. The polymers thus obtained are generally cross linked, as a result of the polyp functionality of the acrylates.
Referring now to Figure l, there is shown in Sue schematic form a capacitor comprising lower electrode 10 which may be aluminum foil, a dielectric coating 11 of a polyfunctional acrylate polymer which may be formed by deposition of one of the above described acrylate compositions on the surface of electrode 10 by, for example, vacuum evaporation or roller coating and suitable polymerization, and upper electrode 12 which is a thin metallized layer of aluminum deposited on dielectric film 11. Leads 13 and 14 are respectively attached to lower and upper electrodes 10 and 12.
Another aspect of the present invention to a method of making a capacitor, said method comprising the steps of forming on a substrate a dielectric coating of a polymer of at least one polyEunctional acrylate as previously described and depositing an electrode layer on said dielectric coating. The coating may be produced by applying the polymer, optionally in solution in a substantially inert solvent, by conventional means such as flowing, spraying dipping, brushing, roller coating, spin coating, drawing down or the like, followed by evaporation of any solvent used. It is usually preferred, however, to apply a polyfunctional acrylate monomer film and subsequently polymerize it by one of the methods previously described. The use of electron beam polymerization is particularly preferred since such a process very rapidly polymerizes the monomer composition without the need for additional curing agents, and thus leads to economical production of very thin coatings In one embodiment of the method of this invention, the substrate is itself a conductive material which may serve as an electrode whereupon the two electrodes and the dielectric coating separating them may constitute the entire capacitor. Figure 4 of the drawing is an illustrative flow diagram of this embodiment which is also illustrated by the following example.
~2;2~3~
Uniform prototype capacitors were produced by drawing down layers of the compositions of Examples 1-11 on an aluminum foil substrate, polymerizing said monomer layer by contact with an electron beam, and depositing a metallic aluminum layer thereon. The thickness of the aluminum foil electrode was 12.5 microns, that of the dielectric layer was 3-6 microns and that of the deposited aluminum electrode was 300-500 Angstroms (0.03-0.05 micron). The areas of the prototype capacitors were about 1 square inch. The dissipation factors of said capacitors were measured at 60 Ho. using an AC bridge.
Figures 2 and 3 graphically depict the relationship between temperature and dissipation factor for typical prototype capacitors prepared as described above in which the polyfunctional acrylate compositions of Examples 1 and 2, respectively, were respectively polymerized by 15- and 10-megarad electron beams to form the dielectric coatings. As is apparent, the dissipation factors remained well below 0.3% from 30 to 130C.
Table III lists the dissipation factors at various temperatures of other typical capacitors made as described above, using the previously described polyfunctional acrylate compositions.
j . ____ ..... _ _ ... I_ .
763~
TABLE III
Electron Dissipation factor, %
beam, Examplemagarads 30C 100C 120C__125C 165C
3 15 1.55 --- 0.25 - - ---4 10 1.05 --- 0.95 --- ------ ox ___ ___ ___
6 10 0.65 --- 1.35 --- ---
7 10 0.65 --- 1.40 --- ---
8 10 0.80 --- 0.85 --- ---
9 10 0.80 --- 0.85 --- 1.10 16 0.60 --- 0.95 --- ---11 15 0.80 --- --- 1.10 ---In another and preferred embodiment ox the method of this invention, alternating electrode layers and dielectric coatings are deposited as described in the aforementioned Canadian application Serial No. 464/171.
The capacitors thus produced have particularly advantageous properties, such as high efficiency, capability of operation at high temperatures, long term electronic stability, favorable failure mode and versatility over a wide range of capacitances. The following examples illustrate some of the advantageous properties of such capacitors.
The procedure described in the aforementioned Canadian Application Serial No 464,171 was used to prepare a capacitor about 18 mm. in width. The substrate was aluminum foil about 50 microns thick. Alternate dielectric thickness about 1 micron) and electrode (thickness about 200-500 Angstroms layers were deposited.
The dielectric layers were wormed by evaporation of the product of Example 12 at 375C and deposition on an electrode surface maintained at 24C, followed by electron beam-initiated polymerization, and the electrode layers by vapor deposition of aluminum. The finished I
KIWI
capacitor contained 1000 layers each of dielectric and deposited electrode. The dissipation factor thereof, measured at 60 Ho. over a 30 15Q C temperature range, varied from a maximum of 3.10% at 30C to a minimum of 0.300% at 150C.
A capacitor was prepared as described in Example 20, except that dielectric was a polymer of the product of Example 17, said product was deposited by evaporation at 400C and deposition at 48C, the thickness of the electrode layers was 300-500 Angstroms and the capacitor contained 200 layers each of dielectric and deposited electrode. the dissipation factor thereof, measured at 100 Ho. over a 30 130 C temperature range, varied from a maximum of 2.8% at 30C to a minimum of 0.7% at 90-130C.
A number of capacitors, prepared as in Example 20 except for numbers of layers and dielectric layer thickness in some cases, were cut to various sizes to provide specific capacitance values and tested for extended periods under the AC voltage and temperature conditions listed in Table II. None of said capacitors had failed at the ends of the test periods listed.
......................
76~31 TABLE IV
Keeps-Dielectric lance, thickness, micro Temp.
Layers microns farads Voltage Cheerios 1000 1.2 0.2 20 130 500 100 1.1 0.19 50 85 66~
930 1.1 0~19 (25 85 68 (50 85 609
The capacitors thus produced have particularly advantageous properties, such as high efficiency, capability of operation at high temperatures, long term electronic stability, favorable failure mode and versatility over a wide range of capacitances. The following examples illustrate some of the advantageous properties of such capacitors.
The procedure described in the aforementioned Canadian Application Serial No 464,171 was used to prepare a capacitor about 18 mm. in width. The substrate was aluminum foil about 50 microns thick. Alternate dielectric thickness about 1 micron) and electrode (thickness about 200-500 Angstroms layers were deposited.
The dielectric layers were wormed by evaporation of the product of Example 12 at 375C and deposition on an electrode surface maintained at 24C, followed by electron beam-initiated polymerization, and the electrode layers by vapor deposition of aluminum. The finished I
KIWI
capacitor contained 1000 layers each of dielectric and deposited electrode. The dissipation factor thereof, measured at 60 Ho. over a 30 15Q C temperature range, varied from a maximum of 3.10% at 30C to a minimum of 0.300% at 150C.
A capacitor was prepared as described in Example 20, except that dielectric was a polymer of the product of Example 17, said product was deposited by evaporation at 400C and deposition at 48C, the thickness of the electrode layers was 300-500 Angstroms and the capacitor contained 200 layers each of dielectric and deposited electrode. the dissipation factor thereof, measured at 100 Ho. over a 30 130 C temperature range, varied from a maximum of 2.8% at 30C to a minimum of 0.7% at 90-130C.
A number of capacitors, prepared as in Example 20 except for numbers of layers and dielectric layer thickness in some cases, were cut to various sizes to provide specific capacitance values and tested for extended periods under the AC voltage and temperature conditions listed in Table II. None of said capacitors had failed at the ends of the test periods listed.
......................
76~31 TABLE IV
Keeps-Dielectric lance, thickness, micro Temp.
Layers microns farads Voltage Cheerios 1000 1.2 0.2 20 130 500 100 1.1 0.19 50 85 66~
930 1.1 0~19 (25 85 68 (50 85 609
10 500 1 0~11 (25 85 68 (50 85 776 500 1.1 0.1 (25 85 68 (50 85 776 These results show the stability of capacitors of this type over prolonged operation periods at relatively high temperature.
In addition to the capacitor structures previously disclosed herein, the present invention is applicable to wound roll and other known types of capacitors. The dielectric coating in suitable cases may be a self-supporting film, instead of being adherently deposited on the electrode substrate.
.,
In addition to the capacitor structures previously disclosed herein, the present invention is applicable to wound roll and other known types of capacitors. The dielectric coating in suitable cases may be a self-supporting film, instead of being adherently deposited on the electrode substrate.
.,
Claims (20)
1. A capacitor comprising two electrodes separated by a dielectric member, said dielectric member comprising a polymer of at least one polyfunctional acrylate having the formula, (I) wherein:
R1 is a hydrocarbon or substituted hydrocarbon radical containing at least 4 carbon atoms;
R2 is hydrogen or an alkyl radical containing 1-5 carbon atoms; and n is from 2 to 6.
R1 is a hydrocarbon or substituted hydrocarbon radical containing at least 4 carbon atoms;
R2 is hydrogen or an alkyl radical containing 1-5 carbon atoms; and n is from 2 to 6.
2. A capacitor according to claim 1 wherein the electrodes are aluminum.
3. A capacitor according to claim 2 wherein R2 is hydrogen or methyl and n is 2 or 3.
4. A capacitor according to claim 3 wherein the polyfunctional acrylate is derived from an aliphatic polyhydroxy compound containing about 4-20 carbon atoms, a polymer having groups capable of reacting with acrylic acid or derivatives thereof and having a number average molecular weight within the range of about 1000-5000, or an aromatic diepoxide or polyepoxide.
5. A capacitor according to claim 4 wherein the polyfunctional acrylate is selected from the group consisting of trimethylolpropane triacrylate, neopentyl glycol diacrylate, bisphenol A diacrylate, diacrylates of diepoxides derived from bisphenol A and ethoxylated derivatives thereof, diacrylates of a,w-alkanediols containing an average of 12-20 carbon atoms and diacrylates of butadiene resins having a number average molecular weight of about 3000.
6. A capacitor according to claim 5 wherein R2 is hydrogen.
7. A capacitor according to claim 5 wherein the polymer is prepared from a blend of polyfunctional acrylates.
8. A capacitor according to claim 7 wherein R2 is hydrogen.
9. A capacitor according to claim 4 wherein the polymer is a copolymer prepared from a mixture of at least one compound of formula I with at least one monoacrylate of the formula (II) wherein R3 is a hydrocarbon or substituted hydrocarbon radical containing about 4-25 carbon atoms.
10. A capacitor according to claim 9 wherein the monoacrylate is cyclohexyl methacrylate.
11. A method of making a capacitor which comprises the steps of forming on a substrate a dielectric coating of a polymer of at least one polyfunctional acrylate having the formula.
(I) , wherein:
R1 is a hydrocarbon or substituted hydrocarbon radical containing at least four carbon atoms;
R2 is a hydrogen or an alkyl radical containing 1-5 carbon atoms; and n is from 2 to 6;
and depositing an electrode layer on said dielectric coating.
(I) , wherein:
R1 is a hydrocarbon or substituted hydrocarbon radical containing at least four carbon atoms;
R2 is a hydrogen or an alkyl radical containing 1-5 carbon atoms; and n is from 2 to 6;
and depositing an electrode layer on said dielectric coating.
12. A method according to claim 11 wherein the dielectric coating is formed by applying a polyfunctional acrylate monomer film and subsequently polymerizing said film.
13. A method according to claim 12 wherein R2 is hydrogen or methyl and n is 2 or 3.
14. A method according to claim 13 wherein the polyfunctional acrylate is derived from an aliphatic polyhydroxy compound containing about 4-20 carbon atoms, a polymer having groups capable of reacting with acrylic acid or derivatives thereof and having a number average molecular weight within the range of about 1000-5000, or an aromatic diepoxide or polyepoxide.
15. A method according to claim 14 wherein the monomer film is polymerized by an electron beam.
16. A method according to claim 14 wherein R2 is hydrogen.
17. A method according to claim 16 wherein the polymer is prepared from a blend of polyfunctional acrylates.
18. A method according to claim 17 wherein R2 is hydrogen.
19. A method according to claim 14 wherein the polymer is a copolymer prepared from a mixture of at least one compound of formula I with at least one monoacrylate of the formula (II) wherein R3 is a hydrocarbon or substituted hydrocarbon radical containing about 4-25 carbon atoms.
20. A method according to claim 19 wherein the monomer film is polymerized by an electron beam.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US562,873 | 1983-12-19 | ||
| US06/562,873 US4499520A (en) | 1983-12-19 | 1983-12-19 | Capacitor with dielectric comprising poly-functional acrylate polymer and method of making |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1227631A true CA1227631A (en) | 1987-10-06 |
Family
ID=24248158
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000470162A Expired CA1227631A (en) | 1983-12-19 | 1984-12-14 | Capacitor with dielectric comprising polyfunctional acrylate polymer and method of making |
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| Country | Link |
|---|---|
| US (1) | US4499520A (en) |
| CA (1) | CA1227631A (en) |
Families Citing this family (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0242462B1 (en) * | 1986-04-21 | 1994-12-28 | SPECTRUM CONTROL, INC. (a Pennsylvania corporation) | Capacitor with dielectric comprising a polymer of polyacrylate polyether pre-polymer |
| US5170318A (en) * | 1991-10-28 | 1992-12-08 | International Business Machines Corporation | Flexible capacitor |
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| US6890363B1 (en) * | 1999-05-24 | 2005-05-10 | Showa Denko K.K. | Solid electrolytic capacitor and method for producing the same |
| US7931787B2 (en) * | 2002-02-26 | 2011-04-26 | Donald Bennett Hilliard | Electron-assisted deposition process and apparatus |
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| US10738143B2 (en) | 2015-08-13 | 2020-08-11 | National Research Council Of Canada | Radiation curable polymer formulation and methods for the preparation thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE520401A (en) * | 1952-06-03 | |||
| US3068510A (en) * | 1959-12-14 | 1962-12-18 | Radiation Res Corp | Polymerizing method and apparatus |
| US3259816A (en) * | 1963-07-12 | 1966-07-05 | Gen Electric | Electrical capacitor with a plastic dielectric |
| US3264536A (en) * | 1964-07-20 | 1966-08-02 | Union Carbide Corp | Capacitor with a polyarylene polyether dielectric |
| GB1168641A (en) * | 1966-05-19 | 1969-10-29 | British Iron Steel Research | Formation of Polymer Coatings on Substrates. |
| US3743532A (en) * | 1969-12-29 | 1973-07-03 | Gen Electric | Coated substrate formed from photopolymerized gas |
| JPS4870855A (en) * | 1971-12-29 | 1973-09-26 | ||
| FR2379889A1 (en) * | 1977-02-08 | 1978-09-01 | Thomson Csf | DIELECTRIC CONSTITUTED BY A THIN LAYER POLYMER, PROCESS FOR MANUFACTURING THE SAID LAYER, AND ELECTRIC CAPACITORS CONTAINING SUCH A DIELECTRIC |
| DE2843581C2 (en) * | 1978-10-05 | 1986-03-27 | Siemens AG, 1000 Berlin und 8000 München | Electric film capacitor and process for its manufacture |
| US4347169A (en) * | 1980-06-30 | 1982-08-31 | Nippon Petrochemicals Company, Limited | Electrical insulating oil and oil-filled electrical appliances |
| US4351746A (en) * | 1980-07-25 | 1982-09-28 | E. I. Du Pont De Nemours And Company | Compound dispersions and films |
| US4329419A (en) * | 1980-09-03 | 1982-05-11 | E. I. Du Pont De Nemours And Company | Polymeric heat resistant photopolymerizable composition for semiconductors and capacitors |
-
1983
- 1983-12-19 US US06/562,873 patent/US4499520A/en not_active Expired - Lifetime
-
1984
- 1984-12-14 CA CA000470162A patent/CA1227631A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4499520A (en) | 1985-02-12 |
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