WO1994002540A1 - Highly filled polymeric compositions - Google Patents

Highly filled polymeric compositions Download PDF

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Publication number
WO1994002540A1
WO1994002540A1 PCT/US1992/006116 US9206116W WO9402540A1 WO 1994002540 A1 WO1994002540 A1 WO 1994002540A1 US 9206116 W US9206116 W US 9206116W WO 9402540 A1 WO9402540 A1 WO 9402540A1
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WO
WIPO (PCT)
Prior art keywords
highly
filler
composition
filled composition
surface active
Prior art date
Application number
PCT/US1992/006116
Other languages
French (fr)
Inventor
Michael F. Lucey
Original Assignee
Lucey Michael F
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lucey Michael F filed Critical Lucey Michael F
Priority to PCT/US1992/006116 priority Critical patent/WO1994002540A1/en
Priority to AU24660/92A priority patent/AU2466092A/en
Publication of WO1994002540A1 publication Critical patent/WO1994002540A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
    • C08K3/013—Fillers, pigments or reinforcing additives
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/28—Applying non-metallic protective coatings
    • H05K3/285—Permanent coating compositions

Definitions

  • This invention relates to a highly filled coating composition.
  • the composition is suitable for use in providing a protective barrier coating on electrical and electronic components and as an ink for printing on various substrates.
  • the composition may include thermoset or thermoplastic polymers.
  • capacitors, and related electrical and electronic components must be, in general, provided with a protective coating.
  • a protective coating must provide ease in handling and be capable of providing the
  • electrical and electronic component certain desired physical, thermal, electrical insulation and moisture resistance properties.
  • the variety of different shapes of electrical and electronic components that are provided with a protective coating present certain unique problems.
  • the composition used must not only provide the desired properties mentioned as a protective coating, it must also be one that can be applied to the component involved using the most suitable coating procedure. Moreover, as with any coating composition, it is desired that the
  • the protective barrier coating on an electrical or electronic component is provided by first coating the electrical and electronic
  • the post curing step of the coating operation may be shortened in some cases by
  • composition used may be, in some cases, either a solid, powdery composition, or, in other cases, one that is liquid, depending somewhat upon the substrate being coated.
  • the use of such a coating composition and procedure is, however, attendant with certain disadvantages.
  • the resinous composition is solvent based, this may create
  • compositions sometimes result in the creation of bubbles and pin-holes in the coating layer created by entrapped air during the curing cycle. Furthermore, conventional thermal curing of resinous coating compositions is not only time consuming but also costly in terms of energy consumption, space,
  • Printing and screening inks are applied to a wide variety of substrates, e.g., metals, metal alloys, paper, thermoplastic and thermosetting resin layers, etc. Nevertheless, particular problems are presented when the substrate is heat sensitive.
  • the ink composition applied must be capable of being cured under conditions not damaging to the substrate.
  • U . S . 3 , 896 , 014 discloses liquid nail lacquer compositions which comprise as the essential components a polyene, a polythiol, a photocuring rate accelerator and, as disclosed by the patentee, a surfactant from a particular class.
  • surfactants are sorbitan
  • trioleate Other surfactants found operative in the composition disclosed, but deemed by the patentee to be somewhat less efficient, include
  • composition as it tended to "bead” when applied to the surface of the nail.
  • U.S. 4,349,605 there are disclosed radiation curable polymeric compositions having flame retardant properties which comprise copolymers of ethylene and a comonomer which may be vinyl ester or an acrylate or a methacrylate, a hydrated inorganic filler, an alkoxy silane, and a lubricant comprising lauric acid and ethylene-bis-stearamide.
  • the filler can, if desired, be silane treated, rather than adding the filler and silane separately to the composition.
  • Such polymeric compositions are disclosed to be preferably cured by radiation means, although
  • cross-linking of the polymers can also be achieved by chemical crosslinking or thermal crosslinking.
  • compositions will hold very large amounts of filler and still provide high flexibility and a high degree of crosslinking. This is deemed by the patentees to be quite surprising as high flexibility and high crosslinking are generally incompatible, as are high crosslinking and high filler loading (which implies low crosslinkable polymer content).
  • high flexibility and high crosslinking are generally incompatible, as are high crosslinking and high filler loading (which implies low crosslinkable polymer content).
  • best results, according to the patentees are obtained when from 44 to 80% by weight of filler in the composition, or 22 to 59% volume of filler, preferably 50 to 57% by weight of filler in the composition, or 26 to 32% volume of filler are employed.
  • U.S. 4,390,401 discloses ultraviolet curable coating compositions which comprise polyunsaturated polyacrylates or methacrylates and as a wetting agent and adhestive promoter an acrylate or methacrylate of a polyalkylene oxide derivative of a mono-hydric alkyl/aryl phenol.
  • an inorganic filler e.g., calcium carbonate, calcium silicate. titanium oxide, aluminum oxide, talc, clay, alumina, calcium hydroxide, and magnesium carbonate, coated with a surfactant.
  • Those surfactants specifically disclosed are stearic acid, lauric acid, rosin, lignin, and cationic surfactant.
  • the treated filler is used at 16.6 to 80% by weight of the composition.
  • the surface-treated filler is claimed to permit UV to penetrate the composition to deep inside, allowing production of thick sheets.
  • the present invention provides a highly, filled composition having a high volume % of filler allowing for the formation of a final durable coating.
  • the highly, filled compositions include a polymeric material at least one filler, and at least one surface active agent.
  • the present invention is based, at least in part, on the discovery that a particular pH relationship between the filler(s) and surface active agent(s) allows for high volume % filler loading of the composition.
  • One of the surface active agent(s) or filler(s) has an overall pH greater than or equal to seven while the other of the surface active agent(s) or filler(s) has an overall pH of less than or equal to seven. The pH's of both components cannot be equal to 7.
  • the present invention also pertains to methods of making the highly, filled compositions, methods of using the highly, filled compositions, and products coated with the highly, filled compositions.
  • the compositions can provide a protective coating on a localized area of, or can fully encapsulate, an electrical or electronic component.
  • the compositions further can be used as a printing ink for the
  • the highly filled compositions of the present invention include a polymeric material, at least one filler, and at least one surface active agent.
  • One of the surface active agent(s) and filler(s) has an overall pH greater than seven and the other of the surface active agent(s) and filler(s) has an overall pH of less than seven.
  • the pH of both components cannot be equal to 7.
  • the pH relationship between the filler(s) and surface active agent(s) enhances the dispersion of the filler(s) in the composition allowing for high filler loading of the composition.
  • polymeric material for purposes of this invention includes polymers, prepolymers and
  • Prepolymers is intended to include materials or subunits capable of being formed or polymerized into polymers, e.g., monomers, dimers, or oligomers.
  • the polymers of the present invention further may be thermoplastic or thermoset polymers.
  • Thermoset polymers are art-recognized and are extensively crosslinked polymers which do not
  • thermoset polymers are cured causing crosslinking forming a final coated product.
  • the curing may be any type of curing which causes crosslinking
  • thermoset polymer systems may include a polymer and/or prepolymer. The systems also may include additional agents which enhance the crosslinking process. Examples of thermoset polymers include the following: phenol-formaldehyde
  • the prepolymer is a material or subunit capable of being polymerized into a polymer.
  • the prepolymer includes monomers.
  • the prepolymer can be any mono- or multifunctional resinous materials having at least one vinyl group.
  • suitable materials for use as the prepolymer are: aliphatic urethane acrylate and methacrylate
  • poly(aeryloxypropylmethyl)-siloxane poly(dimethylsiloxane)- diphenylsiloxane) - (methylvinyl siloxane)
  • aromatic urethane acrylate and methacrylate aromatic urethane acrylate and methacrylate, hydrocarbon urethane acrylate and methacrylate, aromatic epoxy acrylate and methacrylate, and diallyl isophthalate are preferred.
  • the prepolymers may be added to the composition in amounts of from 0 to 70% by weight of the
  • the prepolymer may be a monomer.
  • Monomers used in the compositions of the invention can be mono- or multifunctional, e.g., mono- or multi-functional vinyl monomers.
  • the monomer has at least one vinyl, or unsaturated, group whereby it will, on curing as later more specifically disclosed,
  • thermoset coating or ink e.g., a thermoset coating or ink.
  • Monomers that will be found suitable in the practice of the invention are: cyclohexyl acrylate
  • tripropylene glycol diacrylate 1,6 hexanediol diacrylate
  • dipentaerythritol pentaacrylate dipentaerythritol hexaacrylate vinyl tris (isopropenoxy) silane 1,3,5 trivinyl-1,1,3,5,5- pentamethyltrisiloxane
  • the preferred monomers are alpha, beta unsaturated carboxy compounds.
  • Most preferred monomers are acrylates, and alkacrylates such as isobornyl acrylate, dicyclopentenyl acrylate,
  • 1,6-hexanediol diacrylate 1,6-hexanediol diacrylate, and trimethylol propane triacrylate and alkacrylate relatives of all of the foregoing.
  • these vinyl unsaturated monomers may be added to the composition in amounts ranging from 1 to 70% by weight of the composition, and preferably from about 3 to about 20% by weight of a coating composition used.
  • Photoinitiators and sensitizers suitable for use in the radiation curable compositions of this invention are any of those commonly used for this purpose.
  • compositions of this invention can include various known photosynergists, e.g.
  • alkylamines alkanolamines, and morpholines, or commonly used photoinitiators, e.g. either those involving hydrogen abstraction or intramolecular photocleavage.
  • suitable photosynergists and sensitizers are: alkylamines
  • photoinitiators which can be used in the practice of the invention include:
  • alpha alpha, alpha, alpha
  • the preferred photoinitiators for use in the compositions are 2-2 dimethoxy-2,
  • phenyl-acetophenone 2 hydroxy-2 methyl-1 phenyl propan-1-one, 2 ethylhexyl p-(N, N-dimethylamino) benzoate and 2 isopropylthioxanthone.
  • the amount photoinitiator or sensitizer used will depend somewhat upon that particular one chosen, and the formulation of the compositions, e.g., monomers and prepolymers
  • photoinitiator used will depend upon the desired depth of cure, reaction kinetics, solubility in the system, shelf life of the composition and wavelength of radiation used.
  • the photoinitiators may be added to the composition in amounts ranging from 1 to 15% by weight of the composition; and preferably from about 2 to about 6% by weight of a coating
  • peroxides or other known accelerators will hasten their cure.
  • the thickness of the coating layer is to be greater than about 10 mils, it may be desirable to include in the composition such an accelerator.
  • peroxides that will be found suitable for this purpose, and as an optional component, are: diacyl peroxide
  • thermoplastic polymers are art-recognized and are polymers which soften upon heating and harden upon cooling. The softening/hardening cycles may be repeated many times.
  • thermoplastic polymers include the following: polyethylene
  • Thermoplastic polymer systems typically include a solvent which is evaporated from the system producing a final coating.
  • the solvent can be evaporated at ambient temperature or heating may be used to shorten the evaporation time.
  • thermoplastic system may be any solvent capable of solvating the selected polymer.
  • solvents which may be used in this invention include: polytetrafluoroethylene
  • thermoset containing either thermoset or
  • thermoplastic polymers The type of polymer selected does not effect the ability of the pH relationship between the surface active agent(s) and filler(s) to enhance the filler loading of the composition.
  • compositions disclosed herein include at least one surface active agent.
  • Surface active agents are art-recognized components.
  • the total amount of surface active agent(s) are preferably added to the composition in amounts ranging from about 0.5 and about 4% by weight of the composition.
  • Such agents include various of those components that are variously referred to in the art as surfactants, dispersants or dispersing agents, emulsifiers, suspension agents and solubizers.
  • Silane does not, alone, provide maximum loading of fillers having a negative charge.
  • fillers e.g. calcium metasilicate (wollastonkup)
  • Such fillers disperse only to a certain loading, e.g. about 42% by weight of the composition, or 52% volume of filler, and above that loading, the filler tends to
  • agglomerate when a different surface active agent or a second surface active agent, e.g. phosphate acid ester (such as GAFAC, RE-610), is added to the composition, the filler particles then disperse from one another, with attendant reduction in viscosity (see Table 1, Experiment No. 1).
  • a different surface active agent or a second surface active agent e.g. phosphate acid ester (such as GAFAC, RE-610)
  • the surface active agent to be used can, if desired, be used to coat the filler particles prior to their introduction in the composition. Such a pretreatment of fillers is known, and silane treated fillers are available commercially. Moreover, where two surface active agents are desired in the composition, to obtain maximum loading and polymer properties, the use of a surface active agent coated filler will be found most advantageous.
  • Examples of surface active agents that can be used in the invention are: fish oil (one or more of oleic,
  • anionic/nonionic surfactant blend fatty alcohol ethoxylates organic phosphate ester acid
  • Examples of various surface active agent(s) that can be used in the invention to disperse fillers whose pH is greater than or equal to 7 are: fish oil (one or more of oleic,
  • a most preferred surface active agent is the phosphate acid ester GAFAC, RE-610 to disperse fillers whose pH is greater than or equal to 7. This surface active agent whose pH is less than 7 results in good dispersion of the calcium metasilicate filler whose pH is 9.9 when introduced into the
  • phosphate acids esters which are useful as dispersants are GAFAC: RS-610, RS-410, RE-410, RM-710, RM 510, RM 410, RS-710, RP 710,
  • non-phosphate acid esters such as: fish oil, oleic acid, palmitic acid, and stearic acid.
  • Table 1 is a list of
  • dispersants used herein give higher volume % filler loadings than the previous mentioned dispersants in U.S. Patent Nos. 3,896,014; 4,349,605; and
  • Table 2 is a selected list of dispersants and their effect on untreated filler.
  • dispersants used gave a higher % volume filler than previously disclosed in the patents just listed.
  • surface active agents that can be used in the invention to disperse fillers whose pH is less than or equal to 7 are: polypropoxyglycol methyl diethyl
  • the most preferred surface active agent is the quaternary ammonium salt Emco, CC-42. This surface active agent whose pH is neutral or slightly basic gives good dispersion with carbon black
  • the quaternary ammonium salt gives good dispersion in systems whose filler is a metal and slightly acidic, i.e., electrolytic copper, and nickel. Equally good results are achieved when the metal or metal oxide is neutral. Neutral metals such as copper, silver, palladium, gold, tungsten, platinum, etc. are dispersed in the quaternary
  • ammonium salt Other quaternary ammonium salts which are equally useful as dispersants are Emco: CC-9, CC-55, and the low molecular weight quaternary ammonium salts of methacrylic (acrylic) functionality, such as: BM-604, 2-trimethylammonium ethylmethacrylate chloride, or phosphate, or acetates; BM-613,
  • N-trimethylammonium propylmethacrylamide chloride or phosphates, or acetates
  • BM-607 N-trimethylammonium propylmethacrylamide chloride, or phosphates, or acetates
  • fillers When the fillers are of opposite pH values or one filler is either acidic or basic and the other is neutral then one of the surface active agent (s) must have a pH greater than or equal to 7 and the other surface active agent must have a pH less than or equal to 7.
  • Table 4 illustrates the combining of fillers whose pH values are opposite or where one filler, either acidic or basic, is combined with a neutral filler (inorganic).
  • polyoxyethylene lauryl ether phosphate RD0510 poly(oxy-l, 2-ethanediyl), alpha-phenyl-omega-hydroxy,
  • a filler is an inorganic material (as compared to organic materials composed of carbon, oxygen, hydrogen or nitrogen) capable of occupying a percent of the volume of a composition .
  • the amount of surface active agent used in any particular formulation will depend to some extent on the
  • filler used, the process of manufacturing the filler, its surface area, etc., and the amount of filler to be loaded in the composition.
  • amount filler used will depend somewhat upon the particular application for the coating composition. Where a more fluid flowing coating is desired, for example, in potting electrical and electronic
  • filler examples include barium sulfate
  • examples of fillers that can be used in the compositions of this invention whose pH are less than or equal to 7 are: carbon black
  • inventions may contain a filler from about 20 to about 90% of filler by weight of the composition,
  • compositions are used for coating tantalum capacitors, ceramic disc capacitors, radial film foil capacitors, hybrid circuits, etc.
  • less than about 59% by weight of calcium metasilicate filler in the polymeric composition results in polymer degradation with formation of cracks in the coating when such coating is subject to 125°C for 4,000 hours, a specification which must be met in this application.
  • the amount filler in any composition will depend upon the particular application therefor, i.e., what electrical and electronic component is to be coated, and what physical properties are desired in the cured, polymerized, hardened coating.
  • the manner of coating the substrate will also determine to some extent the concentration of filler. In general, where the coating composition is used to end pour an electrical and electronic component less concentration of filler will be desired than in the case of encapsulating a tantalum capacitor.
  • the pH relationship between the surface active agent and the filler is an important aspect of this invention.
  • filler and surface active agent are selected such that the overall pH of one of the component is less than or equal to 7 while the overall pH of the other components is greater than or equal to 7.
  • the overall pH of both components cannot equal 7.
  • the language overall pH is used to cover the situation where more than one surface active agent or filler is used in the composition.
  • the overall pH is the combined pH of more than one surface active agent or more than one filler.
  • the preferred pH relationship of the present invention is where one of the components has an overall pH greater than 7 while the other component has an overall pH less than or equal to 7.
  • the most preferred pH relationship is where one of the components has a pH greater than 7 while the other component has a pH less than or equal to 7.
  • the volume % of filler in the present invention also is an important aspect of the present invention.
  • the volume % of filler in the composition is sufficiently high to impart durability into a coating formed from the composition.
  • a durable coating is intended to include coatings which do not crack under high humidity conditions (70% relative) at 85°C.
  • the volume % of filler is calculated as follows: the volume % filler is equal to the volume of the filler expressed in cubic centimeters divided by the volume of filler and residual organic
  • the volume % filler of the present invention may be greater than about 50%, preferably greater than about 60%, more preferably greater than about 75%, most preferably greater than about 90%.
  • the term "about” is intended to include a reasonable range on either side of the explicitly stated numerical range, e.g., ⁇ 5%, most preferably ⁇ 3%.
  • compositions in addition to the aforesaid essential ingredients, other components such as disclosed hereinafter can be included in the composition, as desired, and so long as they do not interfere with the curing process. Thus, for example, it may be desirable for a particular application, to include in the composition one or more of the following
  • a wetting agent a plasticizer, a leveling agent, a thixotropic agent, a flame
  • wetting Agents examples of various wetting agents that can be used in the invention are:
  • polyethylene glycol fatty esters nonyl phenol ethylene oxide, fluorinated hydrocarbons, 2,2,3,3 tetrafluoropropylmethacrylate and acrylate,
  • polypropoxy quaternary ammonium acetate polymethylsiloxane, and ammonium salt of sulfated nonylphenoxypoly (ethyleneoxy) ethanol.
  • preferred wetting agents are fluorinated
  • Fc-430 is the fluorinated hydrocarbon used herein that is soluble in the composition and, likewise, lowers the composition's surface tension.
  • Plasticizers examples of various plasticizers that can be used in the invention are: adipates, azelates, benzoates, epoxidized linseed oil, hydrocarbons, phosphates, polyesters,
  • phthalates trimellitates, aliphatic siloxanes, nonionic (polyethylene oxides), anionic (sodium lauryl sulfates), and cationic (cetyl pyridinium chloride) .
  • nonionic polyethylene oxides
  • anionic sodium lauryl sulfates
  • cationic cetyl pyridinium chloride
  • Leveling Agents examples of various leveling agents that can be used in the invention are: sucrose benzoate, copolymer 2-ethylhexyl acrylate and ethyl acrylate, calcium stearate, and nonionic surface active agents.
  • Thixotropic Agents Examples of various thixotropic agents that can be used in the invention are: aluminum, calcium and zinc salts of fatty acids such as lauric or stearic acid; fumed silica,
  • hydrated siliceous material calcium carbonate, magnesium oxide, high molecular weight polyacrylic acids, stearates, polysubstituted sorbitols,
  • Flame Retardants examples of various flame retardants that can be used in the invention are: tetrabromo disphenol A-diacrylate, methyl
  • pentachlorostearate bis(tribromo-phenoloxy) ethane, aluminum trihydrate, antimony oxide, chlorinated paraffins, chlorinated cycloaliphatics, aromatic bromine compounds, phosphates, zinc borates, barium metaborates, ammonium floroborates, decabromodiphenyl oxide, ammonium bromide, and phosphorium bromide.
  • Adhesion Promoters examples of various adhesion promoters that can be used in the invention are: dimethylaminoethyl acrylate and methacrylate, diethlaminoethyl acrylate and methacrylate, silanes, titanates, allyl ether of cyclic ureido,
  • the adhesion will be obtained by first heating the substrate, and then applying the coating composition.
  • stabilizers that can be used in the invention are: 2-hydroxy-4-alkoxy benzophenones, 2(2 hydroxy phenyl) benzotriazole, salicylates, resorcinol monobenzoates, aryl or alkyl hydroxy benzoates, substituted
  • oxanilides substituted formamidine, 2,2 thiobis (4-octylphenolato)-n-butylamine nickel II, nickel salts of thiocarbamate, alkylated phenol phosphonate nickel, and tetramethyl pyperidine.
  • Such compounds will be used as necessary to increase the pot life of the coating or ink composition.
  • Inhibitors examples of various inhibitors that can be used in the invention are: hydroquinone, p-methoxyphenol, alkyl and aryl-substituted
  • hydroquinones and quinones tert-butyl cathechol, pyrogallol, octadecyl-B-(hydroxy-3,5-di-t-butyl ⁇ henyl)-propionate, 2,6-di-tert,-butyl-4-methyl phenol, phosphorous acid, beta-napthol,
  • compositions of this invention will increase the shelf life, as desired.
  • Those skilled in the art of formulating coating compositions can readily determine the amounts of such optional additives, to be added to any particular composition of our invention, for any particular application and desired property. Such materials are, in general, present in the
  • compositions in very minor concentrations ranging from less than 5% by weight of the polymer
  • additives are not included in any significant amount whereby the additives do not interfere with the cross-linking of the polymeric material or to lessen the good properties desired, and achieved, in the cured coating.
  • the components are mixed together by conventional procedures used in the production of inks, and coating compositions. These procedures are so well known to those skilled in the art that they do not require further discussion here. However, it should be noted that when the composition is to be UV cured it will be necessary that the photoinitiator be incorporated into the coating compositions and that the curable coating formulation be mixed or blended under "safe light” such as a yellow light source to obviate or minimize photopolymerization.
  • safe light such as a yellow light source to obviate or minimize photopolymerization.
  • the components can be mixed together and formulated into the desired composition using any conventional mixing apparatus, e.g. a Banbury or Werner & Pfliderer mixer.
  • the components can be added together in any sequence desired.
  • the surface active agent be added first to the prepolymer, monomer mixture followed by addition of the filler. Any processing apparatus used should obtain thorough mixing of the essential components and provide that the surface active agent is intimately and thoroughly dispersed throughout the polymer/monomer mixture.
  • the filler will be pre-treated with a surface active agent. This can be accomplished by using filler coated in a previous operation, or by adding the surface active agent first to the mixer and next dispersing the filler therein.
  • curable coating compositions of this invention can be applied to a suitable surface or substrate, e.g. an electrical and electronic
  • compositions by conventional means such as roll or dip coating, end pouring, spraying, etc. Curing, or photopolymerization of the coating compositions occurs on exposure of the compositions to any source of radiation emitting actinic radiation at a
  • Exposures may be from less than about 4 seconds to 5 minutes or more depending upon the amounts of particular polymerizable materials and photoinitiators being utilized, and depending upon the radiation source and distance from the source, and the thickness of the coating to be cured.
  • the compositions may also be polymerized by exposure to electron beam irradiation without the need of photoinitiator or synergist in the composition. Generally speaking the dosage necessary is from less than 1 megarad to 100 megarad or more.
  • thermoplastic coating compositions of this invention can be applied to a suitable surface or substrate as described above.
  • the solvent can be evaporated from the system at ambient temperature or with the application of some heat.
  • composition is prepared by mixing together the prepolymer, monomer, photoinitiators, sensitizers, wetting agent and dispersant in the weight percentages given below.
  • the mixture is preferably heated to 60°C whereby any solid
  • photoinitiator is completely dissolved, the filler, flame retardant additives and pigment are added and mixing continued for 15 minutes while maintaining a temperature within the range of 60-80°C.
  • the mixture is allowed to cool to ambient conditions before adding the peroxide and bubble breaker. Mixing is resumed at low shear and ambient temperatures until peroxide and bubble breaker are thoroughly mixed.
  • compositions are coated onto dry slug tantalum capacitors by dipping the preheated
  • this electrical and electronic component is 250 mils
  • the coating is further subjected to a postheat treatment for 15 minutes at 85°C.
  • This thermal treatment hastens the further cross-linking of the polymeric composition. Nevertheless, where the coating thickness is less than about 10 mils, no such thermal treatment is needed, as the crosslinking of the polymeric
  • composition is essentially completed during the UV curing.
  • the cured coating composition was evaluated according to usual techniques and was found to exhibit low shrinkage, high tensile and compression strength, as well as broad operating temperatures (-65 to 125°C) over 2000 hours of service life. In addition, the coating is able to withstand high temperature concomitant with high humidity conditions without seriously degrading the electrical behavior of the component.
  • Table 7 illustrates the average electrical properties for twenty units of each of the compositions A-F set forth in Table 6 tested under high temperature (85°C) concomitant with high
  • compositions B and C compositions B and C than for the untreated filler (composition D) .
  • the untreated filler composition showed severe cracking after 500 hours at 125°C.
  • compositions of this invention combine ease in handling with desired physical, thermal, electrical insulation and moisture resistance properties.
  • composition (%wt.)
  • composition (%wt.)
  • *400-NYAD-10024 is calcium metasilicate treated with 1%, Z-6030 silane (Dow Corning) at a 1% by weight silane per calcium metasilicate (Wallastokup)
  • compositions of this example are particularly suitable as protective coatings for smaller electrical and electronic components such as axial leaded film foil capacitors, hybrid circuits, printed circuit boards, transformers, delay lines, electrolytic capacitors, axial leaded resistors, etc., in which the composition is poured into the end of the tape wrapped unit, preformed casing, metal casing, etc.
  • the units, end poured in this example, are axial leaded film foil cylindrical capacitors whose diameter ranges from 0.0625 to 0.25 inches, and whose length ranges from 0.50 to 1.50 inches.
  • compositions (A-H in Table 8) are generally applied by automatic, premeasured,
  • volumetric dispensers Other methods such as spray and dip application before potting are also possible.
  • Coating thicknesses generally range from 0.010 to 0.500 inches.
  • the coating is subjected to UV curing, as before disclosed in Example 1, by exposure for 6 seconds under a medium pressure mercury vapor lamp whose wavelength for curing ranges from 185-400 nm. Afterwards, the coating was
  • Table 9 illustrates the electrical properties taken before and after humidity (95% RH) testing at 75°C for 100 hours. The data is an average of twenty axial leaded film foil capacitor values. Compositions A through H gave good
  • compositions in this example are highly suitable for use in applications involving potting and coating the same electrical components as in Example 2, e.g. axial leaded film foil capacitors, hybrid circuits, printed circuit boards, electrolytic capacitors, transformers, delay lines, resistors. etc.
  • the compositions eliminate, or at least lessen the formation of, pin-holes and bubbles that often form in potting applications due to outgassing of entrapped air during the potting application.
  • the resin system cures quickly forming an air tight seal, hence, preventing escape of air within the electrical and electronic package.
  • Humidity resistance is a characteristic property for the composition of this example as well as its adhesion to aluminum, copper, gold, palladium, and silver.
  • compositions A-H set forth in Table 10 are applied as in Example 2. Units that are end poured in this Example are axial leaded film foil cylindrical capacitors whose diameter ranged from 1.25 to 2.0 inches.
  • composition (%wt.)
  • the resin compositions A-H of this example polymerize to a hard thermoset plastic within 6 seconds of exposure to actinic radiation within the wavelength range of 185-400 nm, from a mercury vapor lamp as earlier disclosed. A postheat treatment for 15 minutes at 85°C was necessary to effect complete cure.
  • the coated film foil capacitor was subjected to operating temperatures between -55 to 105°C for 1000 hours without delamination of the coating from the metallized surface.
  • the pigmentation of the resin did not affect the cure properties of the coating, and did not significantly decrease cure speed.
  • Table 11 illustrates the electrical values for the said capacitor units after humidity (95% RH) testing at 75oC for 100 hours. Measurements are an average of twenty film foil capacitor values.
  • compositions A through H gave good electrical values.
  • compositions A-F set forth in Table 12 are useful for potting or casting electrical and electronic components and may be used in combination with the compositions of Example 3.
  • the rapid cure of the composition in Example 3 allows application of this coating to a substrate that is free of bubbles and pin-holes, often generated during the potting process due to entrapped air within the electrical and electronic components.
  • Example 4 The compositions of Example 4 are applied in a manner as described in Example 2.
  • the end pour units of this example are cylindrical film foil axial leaded capacitors, with a diameter whose range is from 1.0 to 2.50 inches and a length whose range is from 1.25 to 2.0 inches.
  • composition (%wt.)
  • compositions cure within 6 seconds exposure to radiation from a mercury vapor lamp as disclosed in Example 1.
  • a postheat treatment for 15 minutes at 85oC is required to effect complete cure.
  • the said capacitors of Example 4 are humidity (95% RH) tested at 75°C for 100 hours.
  • the data illustrated in Table 13, is an average of twenty film foil capacitor values. Compositions A through F gave good electrical values for coating thicknesses that ranged from 0.010 to 0.090 inches.
  • the cured coatings exhibit uniform grafting to the polymer coating of Example 3, and good
  • compositions A-F set forth in Table 14 are useful in coating hybrid circuits, radial film foil
  • the electrical and electronic components e.g., hybrid circuits, radial film foil capacitors, and ceramic capacitors, are dip-coated into the resin composition of Example 5, and curing is accomplished by exposing the electrical and electronic units to actinic radiation as described in Example 1, for 6 seconds. A second coating application is necessary to ensure complete electrical and electronic
  • the units are exposed to actinic radiation as previously described.
  • the radiation cure is followed by a heat treatment in a convection oven at 85oC for 15
  • the amount of resin used depends upon the configuration and size of the electrical and
  • the resin thickness applied in each case depends upon the type of
  • Coating thicknesses vary anywhere from 0.010 to 0.225 inches per dipping application.
  • Example 5 Electrical values for disc shaped ceramic capacitors of Example 5 are illustrated in Table 15. These measurements are an average of twenty ceramic capacitor values. Compositions A through F gave good electrical values after humidity (95% RH) testing at 85°C for 1000 hours. Example 6
  • An ink composition is prepared by combining the following Table 16 components in the amounts indicated in Table 16.
  • the viscosity of this composition is determined, in accordance with ASTM D115-82, to be 90,000 cps to 300,000 at 25°C.
  • composition is printed onto
  • composition (% wt.)

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Abstract

A highly filled composition is described containing a polymeric material, at least one filler, and at least one surface active agent. The filler(s) and surface active agent(s) are selected based upon the relationship between their pH's allowing for enhanced filler loading of the compositions. The compositions of the present invention can be used to coat electrical and electronic components or as covering substrates.

Description

HIGHLY FILLED POLYMERIC COMPOSITIONS
Field of the Invention
This invention relates to a highly filled coating composition. The composition is suitable for use in providing a protective barrier coating on electrical and electronic components and as an ink for printing on various substrates. The composition may include thermoset or thermoplastic polymers.
Background of the Invention
Electrical and electronic components, e.g., thick and thin film hybrid circuits, tantalum capacitors, axial leaded film-foil capacitors, ceramic disk and tubular capacitors, electrolytic capacitors, radial film foil capacitors, resistors, stacked film
capacitors, and related electrical and electronic components must be, in general, provided with a protective coating. Such a coating must provide ease in handling and be capable of providing the
electrical and electronic component certain desired physical, thermal, electrical insulation and moisture resistance properties. The variety of different shapes of electrical and electronic components that are provided with a protective coating present certain unique problems. The composition used must not only provide the desired properties mentioned as a protective coating, it must also be one that can be applied to the component involved using the most suitable coating procedure. Moreover, as with any coating composition, it is desired that the
protective coating be obtained in the most economical manner without compromise to the various properties desired.
In general, the protective barrier coating on an electrical or electronic component is provided by first coating the electrical and electronic
component, or a portion thereof, with a resinous composition, and then heating the coated component at a suitable temperature and for a suitable length of time whereby the coating composition is cured and adheres to the underlying electrical or electronic component. The post curing step of the coating operation may be shortened in some cases by
preheating the component before application of the resinous coating composition. The coating
composition used may be, in some cases, either a solid, powdery composition, or, in other cases, one that is liquid, depending somewhat upon the substrate being coated. The use of such a coating composition and procedure is, however, attendant with certain disadvantages. In particular, where the resinous composition is solvent based, this may create
environmental considerations. Moreover, such
compositions sometimes result in the creation of bubbles and pin-holes in the coating layer created by entrapped air during the curing cycle. Furthermore, conventional thermal curing of resinous coating compositions is not only time consuming but also costly in terms of energy consumption, space,
equipment, coating material usage and personnel.
Printing and screening inks are applied to a wide variety of substrates, e.g., metals, metal alloys, paper, thermoplastic and thermosetting resin layers, etc. Nevertheless, particular problems are presented when the substrate is heat sensitive. The ink composition applied must be capable of being cured under conditions not damaging to the substrate.
The ultraviolet curing of coating compositions has been known now for sometime. Exemplary of the prior art are United States Patents Nos. 3,896,014; 4 , 349 , 605 ; and 4 , 390 , 401. U . S . 3 , 896 , 014 discloses liquid nail lacquer compositions which comprise as the essential components a polyene, a polythiol, a photocuring rate accelerator and, as disclosed by the patentee, a surfactant from a particular class.
Among the preferred surfactants are sorbitan
sesquioleate, sorbitan dioleate, sorbitan trioleate, pentaerythritol dioleate and pentaerythritol
trioleate. Other surfactants found operative in the composition disclosed, but deemed by the patentee to be somewhat less efficient, include
alkenyldimethylethyl ammonium bromide;
di"coco"dimethyl ammonium chloride' quaternary imidazolinium salt (from stearic acid); glyceryl monooleate; glyceryl dioleate; glyceryl trioleate and polyglyceril ester of oleic acid. Nevertheless, a host of other surfactants were discovered to be inoperative in the invention due to the fact that they were either insoluble in the composition, or they did not improve the wettability of the
composition as it tended to "bead" when applied to the surface of the nail.
In U.S. 4,349,605, there are disclosed radiation curable polymeric compositions having flame retardant properties which comprise copolymers of ethylene and a comonomer which may be vinyl ester or an acrylate or a methacrylate, a hydrated inorganic filler, an alkoxy silane, and a lubricant comprising lauric acid and ethylene-bis-stearamide. The filler can, if desired, be silane treated, rather than adding the filler and silane separately to the composition.
Such polymeric compositions are disclosed to be preferably cured by radiation means, although
cross-linking of the polymers can also be achieved by chemical crosslinking or thermal crosslinking.
According to the patentees, such polymeric
compositions will hold very large amounts of filler and still provide high flexibility and a high degree of crosslinking. This is deemed by the patentees to be quite surprising as high flexibility and high crosslinking are generally incompatible, as are high crosslinking and high filler loading (which implies low crosslinkable polymer content). In compositions used for coating, e.g., extruding onto electrical wire and cables, best results, according to the patentees, are obtained when from 44 to 80% by weight of filler in the composition, or 22 to 59% volume of filler, preferably 50 to 57% by weight of filler in the composition, or 26 to 32% volume of filler are employed.
U.S. 4,390,401 discloses ultraviolet curable coating compositions which comprise polyunsaturated polyacrylates or methacrylates and as a wetting agent and adhestive promoter an acrylate or methacrylate of a polyalkylene oxide derivative of a mono-hydric alkyl/aryl phenol.
Others in addition to the patentees in U.S.
4,349,605 have disclosed using a pretreated filler in a polymeric composition. Thus, in U.S. 2,952,595, it is disclosed that vinyltriethoxysilane treated filler, e.g., hydrated silica, in amounts from about 11 to 34% by weight of the composition or 10 to 30% volume of filler, enhances the beneficial effect that radiation treatment has on the filled polyethylene. Thus, with such treated fillers the impact strength of the compositions was improved, and the brittle point was lowered, in addition to improved torsional hepteresis.
In Japanese 56147846 (Matsushita Electric Works) there is disclosed a photocurable polyester resin composition for the production of thick sheets which comprises unsaturated polyester resin, a
photopolymerization initiator, and an inorganic filler, e.g., calcium carbonate, calcium silicate. titanium oxide, aluminum oxide, talc, clay, alumina, calcium hydroxide, and magnesium carbonate, coated with a surfactant. Those surfactants specifically disclosed are stearic acid, lauric acid, rosin, lignin, and cationic surfactant. According to the abstract, the treated filler is used at 16.6 to 80% by weight of the composition. The surface-treated filler is claimed to permit UV to penetrate the composition to deep inside, allowing production of thick sheets.
For some purposes, it would be desirable to obtain a composition which is sufficiently fluid to allow coating on a substrate yet has a volume % of filler which is sufficiently high to impart
durability into the final formed coating. It is sometimes difficult to achieve the desired volume % of filler in a particular composition.
Summary of the Invention
The present invention provides a highly, filled composition having a high volume % of filler allowing for the formation of a final durable coating. The highly, filled compositions include a polymeric material at least one filler, and at least one surface active agent. The present invention is based, at least in part, on the discovery that a particular pH relationship between the filler(s) and surface active agent(s) allows for high volume % filler loading of the composition. One of the surface active agent(s) or filler(s) has an overall pH greater than or equal to seven while the other of the surface active agent(s) or filler(s) has an overall pH of less than or equal to seven. The pH's of both components cannot be equal to 7.
The present invention also pertains to methods of making the highly, filled compositions, methods of using the highly, filled compositions, and products coated with the highly, filled compositions. The compositions can provide a protective coating on a localized area of, or can fully encapsulate, an electrical or electronic component. The compositions further can be used as a printing ink for the
imprinting of various substrates.
Detailed Description
The highly filled compositions of the present invention include a polymeric material, at least one filler, and at least one surface active agent. One of the surface active agent(s) and filler(s) has an overall pH greater than seven and the other of the surface active agent(s) and filler(s) has an overall pH of less than seven. The pH of both components cannot be equal to 7. The pH relationship between the filler(s) and surface active agent(s) enhances the dispersion of the filler(s) in the composition allowing for high filler loading of the composition.
The term polymeric material for purposes of this invention includes polymers, prepolymers and
combinations thereof. Prepolymers is intended to include materials or subunits capable of being formed or polymerized into polymers, e.g., monomers, dimers, or oligomers. The polymers of the present invention further may be thermoplastic or thermoset polymers.
Thermoset Polymer Systems
Thermoset polymers are art-recognized and are extensively crosslinked polymers which do not
significantly soften upon heating. Typically
thermoset polymers are cured causing crosslinking forming a final coated product. The curing may be any type of curing which causes crosslinking
including radiation, e.g., electron beam, catalyst, humidity or air curing. Thermoset polymer systems may include a polymer and/or prepolymer. The systems also may include additional agents which enhance the crosslinking process. Examples of thermoset polymers include the following: phenol-formaldehyde
melamine-formaldehyde
urea-formaldehyde
polyurethane
unsaturated polyester
epoxy
phenolic anilin
furan
polyester
polyurethane
polyphenylene sulfide
polyimide silicone
poly-p-phenylene benzobisthiazole polyacrylate
polymethacrylate
novolac
phenolic
alkyd
The prepolymer is a material or subunit capable of being polymerized into a polymer. The term
prepolymer includes monomers. For example, the prepolymer can be any mono- or multifunctional resinous materials having at least one vinyl group. Illustrative of suitable materials for use as the prepolymer are: aliphatic urethane acrylate and methacrylate
aromatic urethane acrylate and
methacrylate
polyester urethane acrylate and methacrylate
hydrocarbon urethane acrylate and methacrylate
cycloaliphatic epoxy acrylate and methacrylate
aliphatic epoxy acrylate and
methacrylate
aromatic epoxy acrylate and
methacrylate
amine modified epoxy acrylate and methacrylate
poly(aeryloxypropylmethyl)-siloxane poly(dimethylsiloxane)- diphenylsiloxane) - (methylvinyl siloxane)
polyvinylmethylsiloxane
tetramethlydisiloxane-ethylene
copolymer vinyl
terminated polydumethylsiloxane- vinylmethyl copolymers
acrylated and methacrylated epoxy linseed oil
vinyl unsaturated polyesters polybutadiene acrylate and
methacrylate
polystyrene acrylate and
methacrylate
polyester acrylate and methacrylate vinyl caprolactam
caprolactam acrylate and
methacrylate
silicone acrylates and
methacrylates
melamine acrylate and methacrylate copolymerized amine acrylate and methacrylate
cellulose acrylate and methacrylate cellulose ester ether acrylate and methacrylate
hydrocarbon acrylate and
methacrylate
polyoxyalkylated bisphenol A
acylate and methacrylate acrylamidomethyl substituted
cellulose ester acrylate and methacrylate
1-norbornene spiroorthocarbonate
2-bismethylene spiroorthocarbonate diallyl isophthalate
diallyl maleate
diallyl phthalate
Of the above prepolymers, aromatic urethane acrylate and methacrylate, hydrocarbon urethane acrylate and methacrylate, aromatic epoxy acrylate and methacrylate, and diallyl isophthalate are preferred.
The prepolymers may be added to the composition in amounts of from 0 to 70% by weight of the
composition, and preferably from 3 to 20% by weight of a coating composition. Nevertheless, as will be the case with all the components involved, the amount used will be determined somewhat by the properties desired in the cured composition, which, in turn, will be determined by the particular application involved, i.e., whether the composition is an ink composition or a composition to be used for coating electronic or electrical components. If the latter, the particular formulation desired will also be influenced by the particular components to be coated, including the shape thereof, and the manner of coating to be employed, e.g. dip coating, end pour, roll coating, etc. The prepolymer may be a monomer. Monomers used in the compositions of the invention can be mono- or multifunctional, e.g., mono- or multi-functional vinyl monomers. Preferably, the monomer has at least one vinyl, or unsaturated, group whereby it will, on curing as later more specifically disclosed,
cross-link and form a coating or ink, e.g., a thermoset coating or ink. Monomers that will be found suitable in the practice of the invention are: cyclohexyl acrylate
ethyl acrylate
butyl acrylate
2-ethylhexyl acrylate
2-hydroxyethyl acrylate hydroxypropyl acrylate
N-vinyl-2-pyrrolidone
2-ethoxy ethoxyethyl acrylate
isobornyl acrylate
methyl acrylate
dimethylaminoethyl acrylate
diethylaminoethyl acrylate tetrahydrofurfuryl acrylate
n-hexyl acrylate
n-lauryl acrylate
2-phenoxyethyl acrylate furfuryl-2-acrylate
3-dimethylamino neopentyl acrylate 2-cyanoethyl acrylate
benzyl acrylate
2-N-morpholinoethyl acrylate 2-tert-butyl aminoethyl acrylate N-benzyl methacrylamide
2-(l-aziridinyl)-ethylacrylate methacrylopyethyl phosphate bismethacrylopyethyl phosphate N-(iso-butoxymethyl) acrylamide 3-phenoxy-2-hydroxyproρyl acrylate 3-methacryloxypropyltris
(trimethylsiloxy) silane
3-methacryloxypropylpentamethyl- disiloxane
calcium methacrylate
chromium (III) dimethacrylate sodium methacrylate
magnesium methacrylate
silicone (IV) trimethacrylate tributyl tin methacrylate
zinc methacrylate
zirconium (IV) dimethacrylate 2-methacryloxyethyl phenylurethane dicyclopentenyl acrylate
monomethoxy tripropylene glycol monoacrylate
monomethoxy neopentyl glycol
ethoxylate monacrylate
monomethoxy 1,6 hexanediol
monoacrylate
propargyl methacrylate
isocyanotoethyl methacrylate
2-N-morpholinoethyl acrylate allyl acrylate
styrene vinyl acetate
N-cyclohexyl methacrylamide
N, N'-isovalerylidene- bis-methacrylamide
3,3,5 trimethylcyclohexyl acrylate dihydrodicyclopentadienyl acrylate maleic acid-mono- 2-acryloxyethylester
maleic acid-mono-2- methacryloxyethylester
n-octyl acrylate
diallyl fumarate
tripropylene glycol diacrylate 1,6 hexanediol diacrylate
N, N'-methylenebisacryamide triethylene glycol diacrylate ethylene glycol diacrylate
polyethylene glycol diacrylate
1.3 butylene glycol diacrylate
1.4 butanediol diacrylate
diethylene glycol diacrylate diphenylvinylchlorosilane
1,3 divinyl-1,3 diphenyl-1,3
dimethyldisiloxane
1,3-divinyltetramethyldisiloxane neopentyl glycol diacrylate ethoxylated bisphenol A diacrylate caprolactone diacrylate
2-methyl-2-carboxy propanediol diacrylate
thiodiglycol diacrylate
allyl acrylate dianol diacrylate
3-methylbutene-2-yl-1-acrylate N,N' hexamethylene- bis-methacrylamide
monomethoxy trimethylolpropane
diacrylate
monomethoxy pentaerythritol
propoxylate triacrylate
monomethoxy glycerol propoxylate diacrylate
trimethylol propane triacrylate pentaerythritol triacrylate trimethylolpropane ethoxylate
triacrylate
polyether triacrylate
mono-methoxy pentaerythritol
propoxylate triacrylate
triallylcyanurate
melamine acrylate
tris (2-hydroxy ethyl)
isocyanurate trimethacrylate 1,6 hexanediol diglycidyl ether diacrylate
triallyl trimellitate
pentaerythritol tetraacrylate dipentaerythritol monohydroxypenta acrylate
dipentaerythritol pentaacrylate dipentaerythritol hexaacrylate vinyl tris (isopropenoxy) silane 1,3,5 trivinyl-1,1,3,5,5- pentamethyltrisiloxane The preferred monomers are alpha, beta unsaturated carboxy compounds. Most preferred monomers are acrylates, and alkacrylates such as isobornyl acrylate, dicyclopentenyl acrylate,
1,6-hexanediol diacrylate, and trimethylol propane triacrylate and alkacrylate relatives of all of the foregoing.
In general, these vinyl unsaturated monomers may be added to the composition in amounts ranging from 1 to 70% by weight of the composition, and preferably from about 3 to about 20% by weight of a coating composition used.
Photoinitiators and sensitizers suitable for use in the radiation curable compositions of this invention are any of those commonly used for this purpose. Thus, compositions of this invention can include various known photosynergists, e.g.
alkylamines, alkanolamines, and morpholines, or commonly used photoinitiators, e.g. either those involving hydrogen abstraction or intramolecular photocleavage. Examples of suitable photosynergists and sensitizers are: alkylamines
alkanolamines
morpholines
2-(n-butoxy) ethyl
4-dimethylaminobenzoate
ethyl para dimethyl amino benzoate 2-(dimethylamino) ethyl benzoate diethanol amine
monoethanol amine
dimethylethanol amine
dimethylaminoethyl acrylate and
methacrylate
diethylaminoethyl acrylate and
methacrylate
N-methyldiethanolamine
2-ethylhexyl p-(N, N-dimethylamino)
benzoate
2,2 dithiobisbenzothiazole bis-ethylamino benzophenone
Examples of photoinitiators which can be used in the practice of the invention include:
N,N'dimethylaminobenzophenone
d,1-camphorquinone
2-isopropylthioxanthone
4-isopropylthioxanthone
benzophenone
benzil
2-chlorothioxanthone
2-methylthioanthone
chlorine functional substituted
benzophenone
halogen substituted alkyl-arylketone 4-benzoyl-4-methyl-diphenyl sulphide 2,4,6 trimethylbenzoyldiphenylphosphine oxide
methyl phenylglyoxlate
dibenzosuberone isobutyl benzoin ether
isopropyl benzoin ether
benzoin ethyl ether
benzoin methyl ether
1-phenyl-1,2
propane-dione-2-(O-ethoxycarbonyl) oxime
2-2, dimethoxy-2, phenyl-acetophenone 1,hydroxy cyclo hexyl phenyl ketone
2.2 diethoxyacetophenone
2-hydroxy-2 methyl-1 phenyl propan-1-one 2-methyl-1-(4-methylthio) phenyl)-2-(4 morpholinyl)-1-propanone
4,4'bis-(dimethylamino) benzophenone dibenzosuberone
valerophenone
alpha-tetralone
9-fluorenone
tri-o-tolylphosphine
benz [a] anthacene-7,12-dione
7-H-benz [de] anthracene-7-one
hexanophenone
4,4'dimethoxybenzophenone
4-methoxybenaldehyde
2,4 dimethylthioxanthone
2.3 butanedione
alpha, alpha, alpha
trichloroacetophenone
dimethylsilane-dimethylsiloxane
copolymer The preferred photoinitiators for use in the compositions are 2-2 dimethoxy-2,
phenyl-acetophenone, 2 hydroxy-2 methyl-1 phenyl propan-1-one, 2 ethylhexyl p-(N, N-dimethylamino) benzoate and 2 isopropylthioxanthone.
In general, the amount photoinitiator or sensitizer used will depend somewhat upon that particular one chosen, and the formulation of the compositions, e.g., monomers and prepolymers
involved. However, as a rule of thumb the
photoinitiator used will depend upon the desired depth of cure, reaction kinetics, solubility in the system, shelf life of the composition and wavelength of radiation used. The photoinitiators may be added to the composition in amounts ranging from 1 to 15% by weight of the composition; and preferably from about 2 to about 6% by weight of a coating
composition.
It will be readily appreciated by those skilled in the art that such photoinitiators and sensitizers as set forth above will not be
incorporated in any composition where such is to be cured by electron beam radiation.
Although not a critical feature of the invention, the addition of peroxides or other known accelerators to the compositions disclosed herein will hasten their cure. Thus, in the case where the thickness of the coating layer is to be greater than about 10 mils, it may be desirable to include in the composition such an accelerator. Examples of peroxides that will be found suitable for this purpose, and as an optional component, are: diacyl peroxide
ketone peroxides
peroxydicarbonates
peroxyesters
dialkyl peroxides
hydroperoxides
sulfonyl peroxides
peroxyketals
symmetric and unsymmetric azonitrile dialkyl peroxydicarbonate tetra-alkyl peroxyester
tetra-alkyl hydroperoxide peroxyacids
Thermoplastic Polymer Systems
Thermoplastic polymers are art-recognized and are polymers which soften upon heating and harden upon cooling. The softening/hardening cycles may be repeated many times. Examples of thermoplastic polymers include the following: polyethylene
polypropylene
polystyrene
polyvinyl chloride
polyvinyl alcohol
polytetrafluoroethylene
polytetrafluoroethylene-co-ethylene polymethyl methacrylate polymethyl methacrylate-co-acrylonitrile polystyrene
polystyrene/polybutadiene
polystyrene/polybutadiene-co- arcylonitrile
polybutadiene
polystyrene-co-acrylonitrile
polyoxymethylene
polyethylene terephthalate
polycarbonate
poly e-caprolactam
polyhexamethylene adipamide
polysulfone
cellulose acetate
cellulose acetobutyrate
cellulose
polyisoprene
polybutadiene-co-styrene
polybutadiene-co-acrylonitrile
polychloroprene
polyisobutene-co-isoprene
bromo butyl rubber
polyethylene chlorosulfonated
polyethyl acrylate
polyethylene-co-vinyl acetate
polyethylene-co-propylene
polyurethane rubber
polysulfide rubber
silicone rubber
polyvinyl butyrate
polyvinyl fluoride
polyvinylidene f luorid polyester
polyacetal
polyamide
nitrile
cellulose nitrate
acrylonitrile-butadiene-styrene
polysulphone
polymethylpentene
ethylene/vinyl acetate copolymer polyoxymethylene
polyethylene oxide
polyimide
ethyl cellulose
cellulose propionate
cellulose acetate butyrate polyvinyl acetate
styrene-butadiene copolymers
polyvinyl acetate copolymers
polymethyl methacrylate copolymers
Thermoplastic polymer systems typically include a solvent which is evaporated from the system producing a final coating. The solvent can be evaporated at ambient temperature or heating may be used to shorten the evaporation time. The solvents used in a
thermoplastic system may be any solvent capable of solvating the selected polymer. One of ordinary skill in the art would be able to select a useful solvent for a particular polymer. Examples of solvents which may be used in this invention include: polytetrafluoroethylene
neopentane polyacrylonitrile
water
n-pentane
n-hexane
n-octane
diisopropylketone
cyclohexand
carbon tetrachloride
toluene
xylene
isopropyl alcohol
methyl ethyl ketone
ethyl acetate
dioxane
acetone
pyridine
ethanol
methanol
glycerol
dibutyl phthalate
trixylyl phosphate
butyl acetate
The following description applies to compositions containing either thermoset or
thermoplastic polymers. The type of polymer selected does not effect the ability of the pH relationship between the surface active agent(s) and filler(s) to enhance the filler loading of the composition. Surface Active Aσents
The compositions disclosed herein include at least one surface active agent. Surface active agents are art-recognized components. The total amount of surface active agent(s) are preferably added to the composition in amounts ranging from about 0.5 and about 4% by weight of the composition. Such agents include various of those components that are variously referred to in the art as surfactants, dispersants or dispersing agents, emulsifiers, suspension agents and solubizers.
In some cases, the use of more than one surface active agents is preferred for best results. Silane, for example, does not, alone, provide maximum loading of fillers having a negative charge. Such fillers, e.g. calcium metasilicate (wollastonkup), disperse only to a certain loading, e.g. about 42% by weight of the composition, or 52% volume of filler, and above that loading, the filler tends to
agglomerate. Nevertheless, when a different surface active agent or a second surface active agent, e.g. phosphate acid ester (such as GAFAC, RE-610), is added to the composition, the filler particles then disperse from one another, with attendant reduction in viscosity (see Table 1, Experiment No. 1).
The surface active agent to be used can, if desired, be used to coat the filler particles prior to their introduction in the composition. Such a pretreatment of fillers is known, and silane treated fillers are available commercially. Moreover, where two surface active agents are desired in the composition, to obtain maximum loading and polymer properties, the use of a surface active agent coated filler will be found most advantageous.
Examples of surface active agents that can be used in the invention are: fish oil (one or more of oleic,
palmitic and stearic acid)
anionic polyelectrolyte
linoleic acid
oleic acid
palmitic acid
stearic acid
carboxylic acids
oleoyl acids
stearoyl sarcosine
sodium salt of polycarboxy...
anionic/nonionic surfactant blend fatty alcohol ethoxylates organic phosphate ester acid
acid phosphate ester of fatty alcohol alkoxylate
silanes
titanates
Examples of various surface active agent(s) that can be used in the invention to disperse fillers whose pH is greater than or equal to 7 are: fish oil (one or more of oleic,
palmitic and stearic acid)
anionic polyelectrolyte linoleic acid
oleic acid
palmitic acid
stearic acid
carboxylic acids
oleoyl acids
stearoyl sarcosine
sodium salt of polycarboxylic acids anionic/nonionic surfactant blends fatty alcohol ethoxylates
organic phosphate ester acid methacryloyloxyethane 1, 1
diphosphoric acid
vinyl (acrylic or methacrylic)
substituted polyaliphatic phosphoric acid
vinyl (acrylic or methacrylic)
substituted aromatic
phosphoric acid
vinyl (acrylic or methacrylic)
substituted bisphenol A
phosphoric acid
vinyl (acrylic or methacrylic)
substituted polyethoxy
phosphoric acid
vinyl (acrylic or methacrylic)
substituted polypropoxy
phosphoric acid
acid phosphate ester of fatty
alcohol alkoxylate
maleic mono acryloyloxyethylester maleic mono methacryloyloxyethylester phthalic mono methacryloyloxyethylester methacrylic acid
A most preferred surface active agent is the phosphate acid ester GAFAC, RE-610 to disperse fillers whose pH is greater than or equal to 7. This surface active agent whose pH is less than 7 results in good dispersion of the calcium metasilicate filler whose pH is 9.9 when introduced into the
composition. Other phosphate acids esters which are useful as dispersants are GAFAC: RS-610, RS-410, RE-410, RM-710, RM 510, RM 410, RS-710, RP 710,
PE-510, RD-510, RA-600, and Emphos, PS-21A, and also non-phosphate acid esters such as: fish oil, oleic acid, palmitic acid, and stearic acid. The effect each dispersant has on silane treated calcium
metasilicate (400-NYAD-1024) and untreated calcium metasilicate (400-NYAD) are given in Table 1 and Table 2, respectively. Table 1 is a list of
dispersants and their effect on the treated filler as illustrated by the high volume % filler. The
dispersants used herein give higher volume % filler loadings than the previous mentioned dispersants in U.S. Patent Nos. 3,896,014; 4,349,605; and
4,390,401. Table 2 is a selected list of dispersants and their effect on untreated filler. The
dispersants used gave a higher % volume filler than previously disclosed in the patents just listed. Examples of surface active agents that can be used in the invention to disperse fillers whose pH is less than or equal to 7 are: polypropoxyglycol methyl diethyl
quaternary ammonium chloride
polypropoxyglycol methyl diethyl
quaternary ammonium phosphate
polypropoxyglycol methyl diethyl
quaternary ammonium acetate
cationic/nonionic surfactant blends 2-trimethylammonium
ethylmethacrylate chloride, or phosphates, or acetates
N-trimethylammonium propylmethacrylamide chloride, or phosphates, or acetates 2-trimethylammoniumethyl acrylate
chloride, or phosphate, or acetate
The most preferred surface active agent is the quaternary ammonium salt Emco, CC-42. This surface active agent whose pH is neutral or slightly basic gives good dispersion with carbon black
(Monarch 1,000) whose pH is 2.5 when introduced into the composition. Also, the quaternary ammonium salt gives good dispersion in systems whose filler is a metal and slightly acidic, i.e., electrolytic copper, and nickel. Equally good results are achieved when the metal or metal oxide is neutral. Neutral metals such as copper, silver, palladium, gold, tungsten, platinum, etc. are dispersed in the quaternary
ammonium salt. Other quaternary ammonium salts which are equally useful as dispersants are Emco: CC-9, CC-55, and the low molecular weight quaternary ammonium salts of methacrylic (acrylic) functionality, such as: BM-604, 2-trimethylammonium ethylmethacrylate chloride, or phosphate, or acetates; BM-613,
N-trimethylammonium propylmethacrylamide chloride, or phosphates, or acetates; and BM-607,
2-trimethylammoniumethyl acrylate chloride, or phosphates, or acetates. The effect each dispersant has on carbon black, nickel, and copper are given in Table 3.
When the fillers are of opposite pH values or one filler is either acidic or basic and the other is neutral then one of the surface active agent (s) must have a pH greater than or equal to 7 and the other surface active agent must have a pH less than or equal to 7. Table 4 illustrates the combining of fillers whose pH values are opposite or where one filler, either acidic or basic, is combined with a neutral filler (inorganic).
The monomer, photoinitiator, and surface active agent were mixed at ambient temperature for 15 minutes. Filler was added gradually over 30 minutes, whereby the mixture temperature increased to 85° due to the high shear generated during mixing. The mixture composition upon mixing with dispersant remained fluid, whereas, the mixture composition without dispersant was a solid compact cake of high viscosity. Table 5 is a summary of materials referred to herein by trade or code names listing
corresponding chemical names therefor and available sources of supply.
Table 1
Effect of Dispersant on Silane Treated Calcium Metasilicate Filler
Experiment Number acid average value molecular
Materials 1 2 3 4 5 6 7 8 9 range weight
%wt. %wt %wt. %wt. %wt. %wt. %wt. "Wt. %wt.
Monomer
HDODA. 12.87 12.9 14.8 16.4 12.8 12.8 12.8 12.8 12.8
Photoinitiator
1173 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6
Dispersants
Re-610 1.6 62.72 837
Rs-610 1.6 75-85 701
PS-21A 1.8 130 431
RS-410 3.4 95-115 534
RE-410 3.2 85-100 606
RM-710 1.6 1516
Table 1 (continued)
acid average
value molecular
Materials 1 2 3 4 5 6 7 8 9 range weight
%wt. %wt. %wt. %wt. %wt. %wt. %wt. %wt. %wt
RM-510 1.6 45-55 1122
RM-410 5.1 51-64 975
BH-650 19.4 370-390 147 I
Filler
400-NYAD- 84.0 83.9 81.8 78.7 82.3 82.3 82.6 82.0 82.0
10024
VOLUME % 65.9 65.7 62.4 63.3 65.5 65.6 60.8 47.2
FILLER
Table 1 (continued) acid average value molecular
Materials 10 11 12 13 14 15 16 17 18 range weight
%wt. %wt. %wt. %wt. %wt %wt. %wt. %wt. %wt.
Monomer
HDODA 12.8 12.8 12.8 12.8 12.8 12.8 12.8 12.8 12.8
Photoinitiator
1173 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6
Dispersants
RS-710 2.5 58-70 876
RP-710 5.0 85-100 575
PE-510 5.5 49-59 1039
RD-510 4.9 100-115 522
RA-600 7.3 100-115 522
Table 1 (continued) acid average value molecular
Materials 10 11 12 13 14 15 16 17 18 range weight
%wt. %wt. %wt. %wt. %wt %wt. %wt. %wt. %wt.
RK-500 11.8 132-145 405
BI-750 15.9 250-275 214
2-ethyl- 9.7 389 144 hexoic acid
myristic acid 1.6 247 227
Filler
400-NYAD- 82.4 82 82 82 82 82 82 81 52.7
10024
VOLUME % 64.3 60.9 60.3 61.1 58.2 53.6 50 55.3 54.8
FILLER
Table 1 (continued) acid average value molecular
Materials 19 20 21 22 23 24 range weight
%wt. %wt. %wt. %wt. %wt. %wt.
Monomer
HDODA 12.8 12.8 12.8 12.8 12.8 12.8
Photoinitiator
1173 1.6 1.6 1.6 1.6 1.6 1.6
Dispersants
palmitic 1.9 218 257 acid
steric acid 1.8 198 283 oleic acid 1.6 202 278 fish oil 1.6
Z-6030 2.4
Filler
400-NYAD- 77.2 78 78.6 80 72.22 42.2
10024
VOLUME % 63.6 63.9 64.4 64.8 49.6 51.9
Table 2
Effect of Dispersant on Untreated Calcium Metasilicate Filler
Experiment Number acid average value molecular
Materials 1 2 3 4 5 6 7 8 9 10 range weight
%wt. %wt. %wt. %wt . %wt. %wt. %wt. %wt. %wt. %wt.
Monomer
HDODA 12.8 12.8 12.8 12.8 12.8 12.8 12.8 12.8 12.8 12.8
Photoinitiator
1173 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6
Dispersant
RE-610 1.6 62-72 837
Rs-610 1.6 75-85 701
Ps-21A 1.6 130 431
RE-410 3.5 85-100 606 fish oil 1.6
Table 2 (continued) acid average value molecular
Materials 1 2 3 4 5 6 7 8 9 10 range weight
%wt. %wt. %wt. %wt. %wt. %wt. %wt. %wt. %wt. %wt.
RA-600 8.5 100-115 522 mysteric 1.6 247 227 acid
oleic acid 1.6 202 278
Z-6030 2.6
filler
400 NYAD 83.6 82.0 80.7 81.5 78.0 81.5 51.0 77.6 48.2 41.2
VOLUME % 65.8 51.1 51.4
Table 3
Effect of Dispersant on Carbon, Copper and Nickel
Experiment Number acid average value molecular
Materials 1 2 3 4 5 6 7 8 9 range weight
%wt. %wt. %wt. %wt. %wt. %wt. %wt. %wt. %wt.
Monomer
HPA 8 8 8 5 5 5 5 5 5
Photoinitiator
1173 1.0 1.0 1.0 0.5 0.5 0.5 0.5 0.5 0.5
Dispersants
CC-42 1.6 0.2 0.2 N/A 2,500
CC-9 1.6 0.2 0.2 N/A 2,500
CC-55 1.7 0.2 0.2 N/A 2,500
Filler
Carbon Monarch
1000 89.4 89.4 89.3
Copper
R-290 94.3 94.3 94.3
Nickel
PN200 94.3 94.3 94.3
VOLUME % 83.4 83.4 84.7 66.5 66.5 66.5 66.5 66.5 66.5
FILLER
Table 4
Effect of Dispersant on Filler Whose pH > 7 and Filler Whose pH < 7
Materials 1 2
% wt. % wt
Monomer
HPA 7.0 5.0
Photoinitiator
1173 0.5 0.5
Dispersant pH < 7
0.3
Filler pH > 7
400 NYAD 50.3 50.3
Dispersant pH > 7
CC-42 0.5 0.1
Filler pH < 7
Carbon
Monarch 1000 41.4
(pH < 7)
Nickel
PN 200 (pH=7) 43.8
Volume
Filler 83.8 80.2
Table 5
Materials Used
Code Trade Name/Chemical Name Company
NYCO 400
Wallastonite calcium metasilicate NYCO
NYCO 400
Wollastokup 10024 calcium metasilicate NYCO
(silane treated filler with Z-6030)
231 Lupersol (1, 1-di-t-butylperoxy) Penwalt
-3, 3, 5 trimethylcyclohexane Corp.
Z-6030 -methacryloxypropyltrimethoxysilane Dow
Corning
Anionic GAFACR Surfactant GAF
Chemicals poly(oxy-1, 2-ethanediyl), alpha-(dinonylphenyl)-omega-hydroxy, phosphate; common names:
nonyl nonoxynol-7-phosphate RM-410
nonyl nonoxynol-10-phosphate RM-510
nonyl nonoxynol-15-phosphate RM-710
poly(oxy-1, 2-ethanediyl), alpha-(nonylphenyl)-omega-hydroxy, phosphate; common names:
nonoxynol-9-ρhosphate RE-610
nonoxynol-4-phosphate RE-410
poly(oxy-l, 2-ethanediyl), alpha-tridecyl-omega-hydroxy,
phosphate; common names:
trideceth-6-phosphate RS-610
trideceth-4-phosphate RS-410
trideceth-7-phosphate RS-710
poly(oxy-1, 2-ethanediyl), alpha-dodecyl-omega-hydroxy,
phosphate; common names:
polyoxyethylene lauryl ether phosphate RD0510 poly(oxy-l, 2-ethanediyl), alpha-phenyl-omega-hydroxy,
phosphate or, polyoxyethylene phenyl ether phosphate
RP 710 Table 5
Materials Used
Code Trade Name/Chemical Name Company
3, 6, 9, 12-tetraoxyhexadecan-1-ol, 15 methyl,
dihydrogenphosphate and monohydrogen phosphate; or,
isoamyl alcohol, ethoxylated, phosρhate-BI750 polyphosphoric acids; 2-Butoxyethyl esters polyoxyethylene butoxyethyl ether phosphate, BH-650
poly(oxy-l, 2-ethanediyl), alpha-hexyl-omega-hydroxy-,
phosphate; polyoxyethylene hexyl ether phosphate, RK-500
Fish oil oleic acid, palmitic acid H.J.
and steric acid Baker
& Bro. , Inc.
PS-21A, Emphos, phosphate acid ester. Witco
Chemical
1173 Darocur, 2-hydroxy-2-methyl-1- EM
phenyl-propan-1-one
1573 Epoxy acrylate Resin Cargill,
Inc.
HDODA 1, 6 hexanediol diacrylate Interez TMPTA trimethylolpropane triacrylate Interez Fc430 Fluorad, fluorinated hydrocarbon 3M Oncor Thermoguard S, antimony trioximide M&T
Chemicals Inc.
Air Out petrolium ether Furane
Products
Co.
IR-651 Irgacure, 2, 2 dimethoxy-2, Ciby phenyl-acetophenone Geigy Table 5 (cont'd)
Materials Used
Code Trade Name/Chemical Name Company DCPA dicyclopentenyl acrylate Alcolac DBDPO decabromodiphenyl oxide Great
Lakes
ITX isopropylthioxanthone Ward/
Blenkinship
TBP TRIGONOX-C t-butyl peroctoate Noury
Chemical
Co.
3600 Celrad, amine modified Interez diacrylate ester of bisphenol
A epoxy resin
Cab-o-sil fumed silica Cabot
325, NYAD calcium metasilicate NYCO
325 calcium metasilicate NYCO
Wallastokup-10022 NYAD
L-722 polydimethylsiloxane Union Silwet Carbide
MK 4,4-Bis(dimethylamino)- Eastman benzophenone
Black-F2302 CrCuMnMo Ferro
Color Corp.
Blue-F5203 CoCrAl Ferro
Color Corp.
Green-V7687 CrCoMgAl Ferro
Color Corp. Table 5 (cont'd)
Materials Used
Code Trade Name/Chemical Name Company EPB ethyl-para-dimethylaminobenzoate Ward/
Blenkinsnop
HPA Hydroxypropyl acrylate Rohm
Tech
PETA Pentaerythritol triacrylate Sartomer CC-42 Polypropoxyglycol methyl diethyl Witco quaternary ammonium chloride
CC-55 Polypropoxyglycol methyl diethyl Witco quaternary ammonium acetate
CC-9 Polypropoxyglycol methyl diethyl Witco quaternary ammonium phosphate
Monarch 1000 Carbon black Cabot R-290 Copper powder U.S.
Bronze
PN200 Nickel powder Ametek BM-605 Dimethylaminoethyl acrylate Rhom
Tech
BM-604 2-trimethylammonium Rhom ethylmethacrylate chloride Tech
BM-613 N-trimethylammonium Rhom propylmethacrylamide chloride Tech
BM-607 2-trimethylammoniumethyl Rhom acrylate chloride Tech Table 5 (cont'd)
Materials Used
Code Trade Name/Chemical Name Company Brown-F6114 CrFeSi Ferro
Color Corp.
Yellow-V9400 NiSbTi Ferro
Color Corp.
Ti02 titanium dioxide DuPont ZnS zinc sulfide Aceto
Chemical
Lucirin LR8728 2,4,6 trimethylbenzoyldiphenyl- BASF phosphine oxide
DMAEA demethylaminoethyl acrylate CPS
Chemical
Co.
Butvar (B-79) Polyvinyl butyral Monsanto
MEK methyl ethyl ketone Ashland Tol toluene Ashland DBP dibutyl phthalate Monsanto
Fi ller
A filler is an inorganic material (as compared to organic materials composed of carbon, oxygen, hydrogen or nitrogen) capable of occupying a percent of the volume of a composition . The amount of surface active agent used in any particular formulation will depend to some extent on the
particular filler used, the process of manufacturing the filler, its surface area, etc., and the amount of filler to be loaded in the composition. The amount filler used, in turn, will depend somewhat upon the particular application for the coating composition. Where a more fluid flowing coating is desired, for example, in potting electrical and electronic
components, a lesser amount of filler in general will be used.
Examples of filler that can be used in the compositions of this invention whose pH are greater than or equal to 7 are: barium sulfate
talc
sodium carbonate
zinc oxide
silica
silicates
alumina
aluminates
beryllia
metaborates
calcium sulfate
aluminum silicate phosphates
metasilicates
zirconates
metal oxides
lithium aluminum silicate
wollastonite
titanates
Likewise, examples of fillers that can be used in the compositions of this invention whose pH are less than or equal to 7 are: carbon black
copper
iron oxide
palladium
silver
platinum
glass
nickel
gold
tantalum
tungsten
iron
molybdenum
cadmium
metals
metal oxides
boron
aluminum
titanium
iridiurn In general, the compositions of this
invention may contain a filler from about 20 to about 90% of filler by weight of the composition,
preferably from about 25 to 84% by weight of the composition. Where such compositions are used for coating tantalum capacitors, ceramic disc capacitors, radial film foil capacitors, hybrid circuits, etc., less than about 59% by weight of calcium metasilicate filler in the polymeric composition results in polymer degradation with formation of cracks in the coating when such coating is subject to 125°C for 4,000 hours, a specification which must be met in this application. To some extent the amount filler in any composition will depend upon the particular application therefor, i.e., what electrical and electronic component is to be coated, and what physical properties are desired in the cured, polymerized, hardened coating. Furthermore, the manner of coating the substrate will also determine to some extent the concentration of filler. In general, where the coating composition is used to end pour an electrical and electronic component less concentration of filler will be desired than in the case of encapsulating a tantalum capacitor. pH Relationship of Surface Active Aαent and Filler
The pH relationship between the surface active agent and the filler is an important aspect of this invention. For ease of discussion, either the singular form of "filler" and "surface active agent" will be used but the form is intended to encompass a single filler or surface active agent or a plurality of such agent. The filler and surface active agent are selected such that the overall pH of one of the component is less than or equal to 7 while the overall pH of the other components is greater than or equal to 7. The overall pH of both components cannot equal 7. The language overall pH is used to cover the situation where more than one surface active agent or filler is used in the composition. The overall pH is the combined pH of more than one surface active agent or more than one filler. The preferred pH relationship of the present invention is where one of the components has an overall pH greater than 7 while the other component has an overall pH less than or equal to 7. The most preferred pH relationship is where one of the components has a pH greater than 7 while the other component has a pH less than or equal to 7.
Volume % of Filler
The volume % of filler in the present invention also is an important aspect of the present invention. The volume % of filler in the composition is sufficiently high to impart durability into a coating formed from the composition. A durable coating is intended to include coatings which do not crack under high humidity conditions (70% relative) at 85°C. The volume % of filler is calculated as follows: the volume % filler is equal to the volume of the filler expressed in cubic centimeters divided by the volume of filler and residual organic
material, both expressed in cubic centimeters, whereby the result is multipled by 100. The volume % filler of the present invention may be greater than about 50%, preferably greater than about 60%, more preferably greater than about 75%, most preferably greater than about 90%. The term "about" is intended to include a reasonable range on either side of the explicitly stated numerical range, e.g., ±5%, most preferably ±3%.
Additional Components
In addition to the aforesaid essential ingredients, other components such as disclosed hereinafter can be included in the composition, as desired, and so long as they do not interfere with the curing process. Thus, for example, it may be desirable for a particular application, to include in the composition one or more of the following
components: a wetting agent, a plasticizer, a leveling agent, a thixotropic agent, a flame
retardant, an adhesion promoter, a stabilizer, or an inhibitor, all of which are commonly used in the formulation of coating compositions and inks, to afford certain desired physical properties thereto. To further illustrate the various other additives that may be incorporated in the composition of the invention, the following is given:
Wetting Agents: Examples of various wetting agents that can be used in the invention are:
polyethylene glycol fatty esters, nonyl phenol ethylene oxide, fluorinated hydrocarbons, 2,2,3,3 tetrafluoropropylmethacrylate and acrylate,
fluorinated alkyl polyoxyethylene ethanol,
polypropoxy quaternary ammonium acetate, polymethylsiloxane, and ammonium salt of sulfated nonylphenoxypoly (ethyleneoxy) ethanol. The
preferred wetting agents are fluorinated
hydrocarbons. Fc-430 is the fluorinated hydrocarbon used herein that is soluble in the composition and, likewise, lowers the composition's surface tension.
Plasticizers: Examples of various plasticizers that can be used in the invention are: adipates, azelates, benzoates, epoxidized linseed oil, hydrocarbons, phosphates, polyesters,
phthalates, trimellitates, aliphatic siloxanes, nonionic (polyethylene oxides), anionic (sodium lauryl sulfates), and cationic (cetyl pyridinium chloride) . Those skilled in the art of formulating coating compositions will be able to select that particular plasticizer most suitable in any
particular application. It will be appreciated, as earlier suggested, that use of such a component in any specific case is entirely optional and will depend upon the desired flexibility in the cured coating. For example, it may be desirable to include a plasticizer in a coating composition containing an epoxy acrylate resin, as such compositions, in general, will be found, on curing, to be relatively rigid.
Leveling Agents: Examples of various leveling agents that can be used in the invention are: sucrose benzoate, copolymer 2-ethylhexyl acrylate and ethyl acrylate, calcium stearate, and nonionic surface active agents. Thixotropic Agents: Examples of various thixotropic agents that can be used in the invention are: aluminum, calcium and zinc salts of fatty acids such as lauric or stearic acid; fumed silica,
hydrated siliceous material, calcium carbonate, magnesium oxide, high molecular weight polyacrylic acids, stearates, polysubstituted sorbitols,
bentonite, and chrysotile asbestos. In general, such an additive will be found desirable in compositions used on radial leads, or in applications involving roll coating and dipping. Of the above, fumed silica will be found particularly satisfactory. Also, in addition to the above, it will often be found that any of the fillers above mentioned, will produce the desired thixotropic properties.
Flame Retardants: Examples of various flame retardants that can be used in the invention are: tetrabromo disphenol A-diacrylate, methyl
pentachlorostearate, bis(tribromo-phenoloxy) ethane, aluminum trihydrate, antimony oxide, chlorinated paraffins, chlorinated cycloaliphatics, aromatic bromine compounds, phosphates, zinc borates, barium metaborates, ammonium floroborates, decabromodiphenyl oxide, ammonium bromide, and phosphorium bromide.
Adhesion Promoters: Examples of various adhesion promoters that can be used in the invention are: dimethylaminoethyl acrylate and methacrylate, diethlaminoethyl acrylate and methacrylate, silanes, titanates, allyl ether of cyclic ureido,
zircoaluminate, lignocellulosic, and thiodigylcol diacrylates and methacrylates. In some instances, where greater adhesion is required with a particular substrate coated, the adhesion will be obtained by first heating the substrate, and then applying the coating composition.
Stabilizers: Examples of various
stabilizers that can be used in the invention are: 2-hydroxy-4-alkoxy benzophenones, 2(2 hydroxy phenyl) benzotriazole, salicylates, resorcinol monobenzoates, aryl or alkyl hydroxy benzoates, substituted
oxanilides, substituted formamidine, 2,2 thiobis (4-octylphenolato)-n-butylamine nickel II, nickel salts of thiocarbamate, alkylated phenol phosphonate nickel, and tetramethyl pyperidine. Such compounds will be used as necessary to increase the pot life of the coating or ink composition.
Inhibitors: Examples of various inhibitors that can be used in the invention are: hydroquinone, p-methoxyphenol, alkyl and aryl-substituted
hydroquinones and quinones, tert-butyl cathechol, pyrogallol, octadecyl-B-(hydroxy-3,5-di-t-butyl ρhenyl)-propionate, 2,6-di-tert,-butyl-4-methyl phenol, phosphorous acid, beta-napthol,
2,6-di-tert-butyl p-cresol, 2,2-methylene
bis(4-ethyl-6-t-butylphenol), p-toluquinone, aryl and alkyl phosphites, and benzotriazoles. Addition of such components to the compositions of this invention will increase the shelf life, as desired. Those skilled in the art of formulating coating compositions can readily determine the amounts of such optional additives, to be added to any particular composition of our invention, for any particular application and desired property. Such materials are, in general, present in the
compositions in very minor concentrations, ranging from less than 5% by weight of the polymer
composition, and usually less than 3% by weight of the polymer compositions. In any event, such
additives are not included in any significant amount whereby the additives do not interfere with the cross-linking of the polymeric material or to lessen the good properties desired, and achieved, in the cured coating.
In preparing the coating compositions of this invention, the components are mixed together by conventional procedures used in the production of inks, and coating compositions. These procedures are so well known to those skilled in the art that they do not require further discussion here. However, it should be noted that when the composition is to be UV cured it will be necessary that the photoinitiator be incorporated into the coating compositions and that the curable coating formulation be mixed or blended under "safe light" such as a yellow light source to obviate or minimize photopolymerization.
The components can be mixed together and formulated into the desired composition using any conventional mixing apparatus, e.g. a Banbury or Werner & Pfliderer mixer. The components can be added together in any sequence desired.
Nevertheless, it is preferred that the surface active agent be added first to the prepolymer, monomer mixture followed by addition of the filler. Any processing apparatus used should obtain thorough mixing of the essential components and provide that the surface active agent is intimately and thoroughly dispersed throughout the polymer/monomer mixture.
In the more preferred manner of formulating the compositions of this invention, the filler will be pre-treated with a surface active agent. This can be accomplished by using filler coated in a previous operation, or by adding the surface active agent first to the mixer and next dispersing the filler therein.
The curable coating compositions of this invention can be applied to a suitable surface or substrate, e.g. an electrical and electronic
component, by conventional means such as roll or dip coating, end pouring, spraying, etc. Curing, or photopolymerization of the coating compositions occurs on exposure of the compositions to any source of radiation emitting actinic radiation at a
wavelength within the appropriate ultraviolet or visible spectral regions. Suitable sources of radiation include mercury, xenon, carbon arc and tungsten filament lamps, sunlight, etc. Exposures may be from less than about 4 seconds to 5 minutes or more depending upon the amounts of particular polymerizable materials and photoinitiators being utilized, and depending upon the radiation source and distance from the source, and the thickness of the coating to be cured. The compositions may also be polymerized by exposure to electron beam irradiation without the need of photoinitiator or synergist in the composition. Generally speaking the dosage necessary is from less than 1 megarad to 100 megarad or more.
The thermoplastic coating compositions of this invention can be applied to a suitable surface or substrate as described above. The solvent can be evaporated from the system at ambient temperature or with the application of some heat.
The following examples, in which all parts are expressed by weight percent of total composition will serve to illustrate the invention more fully.
Example 1
UV Curable, Highly Thixothropic,
Flame Retardant Conformal Coating for Electrical and Electronic Components
This example illustrates the effectiveness of the composition in coating pear-shaped electrical and electronic components such as tantalum capacitors
The composition is prepared by mixing together the prepolymer, monomer, photoinitiators, sensitizers, wetting agent and dispersant in the weight percentages given below. The mixture is preferably heated to 60°C whereby any solid
photoinitiators are dissolved. When the
photoinitiator is completely dissolved, the filler, flame retardant additives and pigment are added and mixing continued for 15 minutes while maintaining a temperature within the range of 60-80°C. The mixture is allowed to cool to ambient conditions before adding the peroxide and bubble breaker. Mixing is resumed at low shear and ambient temperatures until peroxide and bubble breaker are thoroughly mixed.
These compositions are coated onto dry slug tantalum capacitors by dipping the preheated
capacitors at 85°C into the resin composition and withdrawing the units on chipboards with mechanical agitation. Units are then exposed to actinic
radiation within the wavelength region of 185-400 nm for 5 seconds. The same units are subsequently dipped a second time and exposed again to the said radiation for 5 seconds. Coating thicknesses of 250 mils were necessary to ensure complete coverage of the "hockey stick" leads that make up the cathode and anode functions of the capacitor.
As the coating thickness of this electrical and electronic component is 250 mils, the coating is further subjected to a postheat treatment for 15 minutes at 85°C. This thermal treatment hastens the further cross-linking of the polymeric composition. Nevertheless, where the coating thickness is less than about 10 mils, no such thermal treatment is needed, as the crosslinking of the polymeric
composition is essentially completed during the UV curing.
The cured coating composition was evaluated according to usual techniques and was found to exhibit low shrinkage, high tensile and compression strength, as well as broad operating temperatures (-65 to 125°C) over 2000 hours of service life. In addition, the coating is able to withstand high temperature concomitant with high humidity conditions without seriously degrading the electrical behavior of the component. Table 7 illustrates the average electrical properties for twenty units of each of the compositions A-F set forth in Table 6 tested under high temperature (85°C) concomitant with high
humidity (95%RH) conditions for 1,000 hours. In the table, electrical properties are better for the treated filler with dispersant added (composition A) and for the treated filler without dispersant
(compositions B and C) than for the untreated filler (composition D) . The untreated filler composition showed severe cracking after 500 hours at 125°C.
As this example shows, the compositions of this invention combine ease in handling with desired physical, thermal, electrical insulation and moisture resistance properties. TABLE 6
Dry Slung Tantalum Capacitor Compositions
Composition (%wt.)
Materials A B C D E F
Prepolymer
1573 5.5 4.0 5.0 9.0
Monomer
DCPA 6.0 4.0 7.6 8.3
TMPTA 6.5 12.5 10.7 8.0
HDODA
BM-605 1.5 1.5
HPA 5 5
PETA 6 6
Wetting Agent
FC430 0.8 1.3 1.3 0.8
Photoinitiator
& Sensitizers
IR-651 2.0 2.1 2.1 2.1 1.5 1.5
ITX 1.0 0.7 0.7
EBP 1.5
Dispersant
RE-610 1.3 1.3 1.0
CC-42 0.3
TABLE 6 (CONT.)
Dry Slung Tantalum Capacitor Compositions
Composition (%wt.)
Materials A B C D E F
Flame Retardants
Oncor 2 2 2 2.0 1.8 1.8
DBDPO 5.7 5.7 5.7 5.7 5.4 5.4
Fillers
*400-NYAD-10024 66 62.8 61.5 75.8 65.
(Wallastonite)
*400-NYAD
(Wallastonite) 61.5
Monarch 1000 10.0
Pigment
Dye 0.5 0.5 0.5 0.5 0.5 0.5
Peroxide
TBP 5.0 3.5 2.0
L-231 1 0.5 0.5
Bubble Breaker
Air Out 0.1 0.1 0.1 0.1
*400-NYAD-10024 is calcium metasilicate treated with 1%, Z-6030 silane (Dow Corning) at a 1% by weight silane per calcium metasilicate (Wallastokup)
Table 7
Electrical Properties
Humidity at 85°C, 95%RH, for 1,000 hours
Testing Done at 0.5V, 12Hz
Compo- Initial Electrical Final Electrical sition Values Values
CAP(uf) DF(%) ESR(ohm) CAP(uf) DF(%) ESR(ohm)
A 48.40 3.60 0 .99 49.52 3.80 1.04
B 49.11 3.72 1 .01 51.00 4.29 1.12
C 48.87 3.37 .91 50.70 3.89 1.02
D* 49.21 3.42 .92 51.57 6.74 1.66
E 48.6 3.61 .97 49.71 3.81 1.02
F 49.0 3.47 .93 52.0 5.63 1.46
*Test done for only 500 hours. Parts are severely split.
CAP - Capacitance in microfarads
DF - dissipation factor in percent
ESR - electrical series resistance ih ohms
Example 2
Low Viscosity, Flame Retardant,
UV Curable End Pour System for Smaller
Electrical and Electronic Components
The compositions of this example are particularly suitable as protective coatings for smaller electrical and electronic components such as axial leaded film foil capacitors, hybrid circuits, printed circuit boards, transformers, delay lines, electrolytic capacitors, axial leaded resistors, etc., in which the composition is poured into the end of the tape wrapped unit, preformed casing, metal casing, etc.
The units, end poured in this example, are axial leaded film foil cylindrical capacitors whose diameter ranges from 0.0625 to 0.25 inches, and whose length ranges from 0.50 to 1.50 inches.
TABLE 8
End Pour Encapsulant
Composition (%wt )
Materials A B C D E F G H
Prepolymer
1573 10 10 10
Monomer
DCPA 12 20.3 13 21.1 12 20.3
HD0DA 14 14 14
TMPTA 10.5 10.5 10.5
HPA
PETA
Photoinitiator
IR-651 2.1 2.1 2.1 2.1 2.1 2.1 1.5 1.5
Dispersant
RE-610 1.0 0.9 1.0 1.0 1.2 1.0
CC-44 0.3
Pigment
Dye 1.2 1.2 1.2 1.2 1.2 1.2 0.7 0.7
Flame Retardent
Oncor 2 1.7 1.7
DBDPO 5.7 5.7 5.7 5.7 5.7 5.7 5.7 5.7
Filler
NYAD-325 50 46.3
NYAD-325-10022 50 46.3 50 46.3 74.5 64.4
Monarch 1000 10.0
Peroxide
TBP 2 2 2 2 22 22 0.7 .07 Viscosity 550 1000 750 1200 400 800 10,000 15,000 (cps; centipoise) Table 9
Electrical Properties
End Pour, "Mylar" Tape Wrapped Capacitors
Humidity at 75ºC, 95%RH, for 100 hours
CompoIni .tial Electrical Final Electrical sition Values Values
CAP(uf) DF(%) ESR(ohm) CAP(uf) DF(%) ESR(ohm)
A 10.41 .004 .01 10.46 .004 .01
B 10.37 .004 .01 10.38 .004 .01
C 10.30 .003 .01 10.28 .003 .01
D 10.39 .004 .01 10.41 .004 .01
E 10.37 .004 .01 10.41 .004 .01
F 10.21 .003 .01 10.28 .003 .01
G 10.38 .003 .01 10.41 .003 .01
H 10.31 .003 .01 10.34 .003 .01
The above compositions (A-H in Table 8) are generally applied by automatic, premeasured,
volumetric dispensers. Other methods such as spray and dip application before potting are also
possible. Coating thicknesses generally range from 0.010 to 0.500 inches. The coating is subjected to UV curing, as before disclosed in Example 1, by exposure for 6 seconds under a medium pressure mercury vapor lamp whose wavelength for curing ranges from 185-400 nm. Afterwards, the coating was
subjected to a post heat treatment of 85ºC for 15 minutes, to effect complete cure.
Table 9 illustrates the electrical properties taken before and after humidity (95% RH) testing at 75°C for 100 hours. The data is an average of twenty axial leaded film foil capacitor values. Compositions A through H gave good
electrical values. These compositions are
particularly effective in eliminating bubbles and pin-holes often created by entrapped air in the end-pour units.
Example 3
Low Viscosity, UV Curable
Potting System
The compositions in this example are highly suitable for use in applications involving potting and coating the same electrical components as in Example 2, e.g. axial leaded film foil capacitors, hybrid circuits, printed circuit boards, electrolytic capacitors, transformers, delay lines, resistors. etc. The compositions eliminate, or at least lessen the formation of, pin-holes and bubbles that often form in potting applications due to outgassing of entrapped air during the potting application. The resin system cures quickly forming an air tight seal, hence, preventing escape of air within the electrical and electronic package. Humidity resistance is a characteristic property for the composition of this example as well as its adhesion to aluminum, copper, gold, palladium, and silver.
The compositions A-H set forth in Table 10 are applied as in Example 2. Units that are end poured in this Example are axial leaded film foil cylindrical capacitors whose diameter ranged from 1.25 to 2.0 inches.
Table 10
End Pour Encapsulant
Composition (%wt.)
Materials A B C D E F
Prepolymer
1573 10 10 10
Monomer
DCPA 12 20.3 12 20.3 12 20.3
HDODA 14 15 14
TMPTA 10.5 11.4 10.5
HPA
PETA
Photoinitiator
IR-651 2.1 2.1 2.1 2.1 2.1 2.1 1.5 1.5
Dispersant
RE-610 1.0 0.9 1.0 0.9 1.3 1.2
CC-42 0.2
Filler
NYAD-325 58.9 55.2 84.5 74.4
NYAD-325- -10022 58.9 55.2 58.9 55.2
Monarch 1000 10.0
Peroxide
TBP 2 2 2 2 2 2 0.7 0.7 Viscosity(cps) 1700 2000 2300 2500 1500 1800 9000 14,000 Table 11
Electrical Properties
End Pour, "Mylar" Tape Wrapped Capacitors
Humidity at 75°C, 95%RH, for 100 hours
CompoInitial Electrical Fiiαal Electrical sition Values Values
CAP(uf) DF(%) ESR(ohm) CAP(uf) DF(%) ESR(ohm)
A 9.87 .05 .01 9.94 .05 .01
B 10.21 .04 .01 10.18 .04 .01
C 9.92 .03 .01 9.93 .03 .01
D 9.85 .04 .01 9.97 .04 .01
E 9.92 .04 .01 9.98 .04 .01
F 9.84 .03 .01 9.96 .03 .01
G 9.96 .04 .01 9.99 .04 .01
H 9.89 .04 .01 9.98 .04 .01
The resin compositions A-H of this example polymerize to a hard thermoset plastic within 6 seconds of exposure to actinic radiation within the wavelength range of 185-400 nm, from a mercury vapor lamp as earlier disclosed. A postheat treatment for 15 minutes at 85°C was necessary to effect complete cure.
The coated film foil capacitor was subjected to operating temperatures between -55 to 105°C for 1000 hours without delamination of the coating from the metallized surface. The pigmentation of the resin did not affect the cure properties of the coating, and did not significantly decrease cure speed.
Table 11 illustrates the electrical values for the said capacitor units after humidity (95% RH) testing at 75ºC for 100 hours. Measurements are an average of twenty film foil capacitor values.
Compositions A through H gave good electrical values.
Example 4
Low Viscosity, UV Curable Coating System for Electrical and Electronic Components
The compositions of this example
(compositions A-F set forth in Table 12) are useful for potting or casting electrical and electronic components and may be used in combination with the compositions of Example 3. The rapid cure of the composition in Example 3 allows application of this coating to a substrate that is free of bubbles and pin-holes, often generated during the potting process due to entrapped air within the electrical and electronic components.
The compositions of Example 4 are applied in a manner as described in Example 2. The end pour units of this example are cylindrical film foil axial leaded capacitors, with a diameter whose range is from 1.0 to 2.50 inches and a length whose range is from 1.25 to 2.0 inches.
Table 12
End Pour Encapsulant
Composition (%wt.)
Materials A B C D E F
Prepolymer
1573 10 10 10
3600
Monomer
DCPA 10.2 4 11.2 5.0 10.2 4
TMPTA 10.5 15 10.5 15 10.5 15
Photoinitiator
IR-651 2.1 2.1 2.1 2.1 2.1 2.1
Dispersant
RE-610 1.0 1.0 1.0
Piσment
Dye 1.2 1.2 1.2 1.2 1.2 1.
Flame Retardant
Oneor 2 2 2 2 2 2
DBDPO 5.7 5.7 5.7 5.7 5.7 5.
Filler
NYAD-325 56.3 57
NYAD-325-10022 56.3 57 56.3 57
Peroxide
TBP 2 2 2 2 2 2
Viscosity(cps) 9100 13,200 10,000 14,100 8000 11,100 Table 13
Electrical Properties
End Pour, "Mylar" Tape Wrapped Capacitors
Humidity at 75°C, 95%RH, for 100 hours
CompoInitial Electrical Final Electrical sition Values Values
CAP(uf) DF(%) ESR(ohm) CAP(uf) DF(%) ESR(ohm)
A 9.42 .05 .01 9.63 .05 .01
B 9.32 .05 .01 9.52 .05 .01
C 8.22 .04 .01 8.32 .04 .01
D 8.18 .06 .01 8.26 .06 .01
E 8.20 .07 .01 8.29 .07 .01
F 9.61 .05 .01 9.73 .05 .01
These compositions cure within 6 seconds exposure to radiation from a mercury vapor lamp as disclosed in Example 1. A postheat treatment for 15 minutes at 85ºC is required to effect complete cure.
The said capacitors of Example 4 are humidity (95% RH) tested at 75°C for 100 hours. The data illustrated in Table 13, is an average of twenty film foil capacitor values. Compositions A through F gave good electrical values for coating thicknesses that ranged from 0.010 to 0.090 inches.
The cured coatings exhibit uniform grafting to the polymer coating of Example 3, and good
adhesion to metallic substrates.
In many cases, a satisfactory coating may be achieved without pre-coating the electrical and electronic components with the composition of Example 3.
Example 5
Flame Retardant, UV Curable Conformal
Coatings for Hybrid Circuits, Radial Film
Foil Capacitors, and Ceramic Capacitors
The compositions of this example
(compositions A-F set forth in Table 14) are useful in coating hybrid circuits, radial film foil
capacitors and ceramic capacitors due to their ability to withstand high humidity environments and temperature extremes from -55 to 125°C. Table 14
Hybrid Circuit, Radial Film Foil Capacitor,
Ceramic Capacitor Encapsulant
Composition (%wt )
Materials A B C D E F
Prepolymer
1537 8.5 6.3 7.6
Monomer
DCPA 7.5 4.0 4.0
TMPTA 4.3 4.7 4.7
BM-605 2.0
HPA 5.0 5.0 5.0
PETA 6.0 6.0 6.0
Wetting Agent
Fc-430 0.8 0.8
Plasticizer
L-722 3.5 3.0 3.0
Photoinitiator
IR-651 2.8 2.0 2.0 1.5 1.5 1.5
ITX 2.0 2.0 1.0
MK 0.7
EPB 2.0
Dispersant
RE-610 1.6 1.6 1.4 1.3 1.4
CC-42 0.2
Pigment
Dye 0.8 0.6 0.6 0.5 0.5 Table 14 (continued)
Materials A B C D E F
Flame Retardant
Oncor 2 1.9 1.9 1.8 1.8
DBDPO 10.5 5.7 5.7 5.7 5.7
Filler
400-NYAD- 52.6 64.3 64.3 74.3 67.8 84.9
10024
Monarch 1000 10
Bubble breaker
Air Out 0.1 0.1 0.1
Peroxide
TBP 5.5
L231 1.0 1.0 0.7 0.7 0.7
Table 15
Electrical Properties
Ceramic Capacitors
Humidity at 85°C, 95%RH, for 1000 hours
CompoInitial Electrical Final Electrical sition Values Values
CAP(uf) DF(%) ESR(ohm) CAP(uf) DF(%) ESR(ohm)
A 48.12 1.21 0.40 47.79 1.21 0.39
B 48.95 1.19 0.39 49.12 1.17 0.42
C 49.14 1.29 0.42 49.46 1.32 0.44
D 49.12 1.30 0.44 49.40 1.31 0.44
E 48.66 1.19 0.40 49.12 1.22 0.42
F 48.67 1.21 0.41 49.23 1.26 0.44
The electrical and electronic components, e.g., hybrid circuits, radial film foil capacitors, and ceramic capacitors, are dip-coated into the resin composition of Example 5, and curing is accomplished by exposing the electrical and electronic units to actinic radiation as described in Example 1, for 6 seconds. A second coating application is necessary to ensure complete electrical and electronic
component coverage. After a second costing, the units are exposed to actinic radiation as previously described. The radiation cure is followed by a heat treatment in a convection oven at 85ºC for 15
minutes. The amount of resin used depends upon the configuration and size of the electrical and
electronic component. Also, the resin thickness applied in each case depends upon the type of
components surface mounted on the hybrid circuit, upon the type of attachment of lead wires to the ceramic capacitor and size of the ceramic capacitor, and upon the size, and shape, and roughness of the radial film foil capacitor. Coating thicknesses vary anywhere from 0.010 to 0.225 inches per dipping application.
Electrical values for disc shaped ceramic capacitors of Example 5 are illustrated in Table 15. These measurements are an average of twenty ceramic capacitor values. Compositions A through F gave good electrical values after humidity (95% RH) testing at 85°C for 1000 hours. Example 6
UV Curable Printing Ink for
Heat Sensitive Substrate
An ink composition is prepared by combining the following Table 16 components in the amounts indicated in Table 16.
The viscosity of this composition is determined, in accordance with ASTM D115-82, to be 90,000 cps to 300,000 at 25°C.
The composition is printed onto
polypropylene, mylar, and polystyrene (heat
sensitive), in accordance with usual techniques, after which it is exposed to actinic radiation as previously described in Example 1, for 2 seconds.
These ink formulations are tested according to Military Standards 883C and all inks pass.
Table 16
Ink Formulations for Heat Sensitive Substrates
Composition (% wt.)
Material A B
Prepolymer
1570 50 50 50 50 50 40
Dispersant
Re-610 0.04 0.04 0.04 0.04 0.04 0.04 1.6 0.5
CC-42 1.4 0.8
Monomer
TMPTA 32.96 32.96 32.96 32.96 32.96 32.6
HPA 5
PETA 6
Photoinitiator
IR-651 6
Lucirin LR8728 0.5 0.5
ITX 2.5 2.5 2.5 2.5 2.5 1.5 1.5
BP 1.5 1.5 1.5 1.5
DMAEA 3.5 3.5 3.5 3.5 3.5 2.0 2.0 2.0 2.0
Table 16 ( continued) Material A B C D E F G H I
Thixotropic agent
Cab-o-sil 3 3 3 3 3 3.0 1.0 1.0
Pigment
Black
F2302 2 81.6 52.7
Blue
F5203 2
Green 2
Brown 2
Yellow 2
TiO2 10 30 30
ZnS 10 52.4
Table 17
Ink Formulations for Non-Heat Sensitive Substrates
Composition (% wt.)
Material A B C D E F G H
Prepolymer
1570 45 45 45 45 45
Dispersant
RE-610 0.1 0.1 0.1 0.1 0.1 1.6 0.5
CC-42 1.4 0.8
Monomer
TMPTA 34.9 34.9 34.9 34.9 34.9
HPA
PETA
Photoinitiator
IR-651 6
Lucirin LR8728 0.5
ITX 2.5 2.5 2.5 2.5 2.5 1.0 1.0
BP 1.0 1.0 1.0
Thixotropic agent
Cab-o-sil 3 3 3 3 1.0 1.0
Pigment
Black 5 84.6 53.7
Blue 5
Green 5
Brown 5
Yellow
TiO2 30 30 ZnS 53.9 Example 7
UV Curable Composition for
Non-Heat Sensitive Substrate
A further ink composition is prepared for non-heat sensitive substrates by mixing together the following Table 17 components illustrated in Table 17,
These compositions, which had viscosity of 90,000 cps at 25°C, are printed onto an aluminum can and cured as in the previous example for 8 seconds. The ink compositions exhibit properties comparable to those of the previous example.
Example 8
Thermoplastic polymer containing
compositions were prepared as shown in Tables 18-20. The thermoplastic polymer used is Butvar (B79) as described in Table 18 and the volume % filler ranged from 46.1 to 95%.
Table 18
NYAD and Carbon Fillers
Experiment Number
Materials 1 2 3 4 5 6 7
%wt %wt. %wt. %wt. %wt. %wt. %wt
Polymer
Butvar 7.0 7.0 7.0 7.0 7.0 7.0 7.0
B79
Solvents
MEK. 12.0 12.0 12.0 12.0 12.0 12.0 12.0
Tol. 18.0 18.0 18.0 18.0 18.0 18.0 18.0
DBP 1.3 1.3 1.3 1.3 1.3 1.3 1.3
Fillers
NYAD 400 61.1 51.15 41.2 31.1 21.2 11.2
CB(1000) 10.0 20.0 30.15 40.1 50.2 61.4
Dispersants
Re-610 0.6 0.5 0.4 0.3 0.2 0.1
CC-42 0.05 0.1 0.15 0.2 0.2 0.3
VOLUME % 69.2 71.2 72.9 74.5 75.9 77.3 78.4
FILLER
Table 19
NYAD and Copper Fillers
Experiment Number
Materials 1 2 3 4 5 6
%wt. %wt %wt. %wt. %wt %wt
Polymer
Butvar 7.0 7.0 7.0 7.0 7.0 7.0
B79
Solvents
MEK. 12.0 12.0 12.0 12.0 12.0 12.0
Tol. 18.0 18.0 18.0 18.0 18.0 18.0
DBP 1.3 1.3 1.3 1.3 1.3 1.3
Fillers
NYAD 400 51.15 41.2 31.1 21.2 11.2
Copper 10.0 20.0 30.15 40.1 50.2 61.4
R290
Dispersants
Re-610 0.5 0.4 0.3 0.2 0.1
CC-42 0.05 0.1 0.15 0.2 0.2 0.3
VOLUME % 67.0 64.3 61.2 57.5 53.0 46.1
FILLER
Table 20
NYAD and Nickel Fillers
Experiment Number
Materials 1 2 3 4 5 6
%wt. %wt %wt. %wt. %wt. %wt
Polymer
Butvar 7.0 7.0 7.0 7.0 7.0 7.0
B79
Solvents
MEK. 12.0 12.0 12.0 12.0 12.0 12.0
Tol. 18.0 18.0 18.0 18.0 18.0 18.0
DBP 1.3 1.3 1.3 1.3 1.3 1.3
Fillers
NYAD 400 51.15 41.2 31.1 21.2 11.2
Nickel 10.0 20.0 30.15 40.1 50.2 61.4
PN200
Dispersants
Re-610 0.5 0.4 0.3 0.2 0.1
CC-42 0.05 0.1 0.15 0.2 0.2 0.3
VOLUME % 95.0 94.6 94.2 93.6 93.3 91.3
FILLER
It will now be apparent to those skilled in the art that other embodiments, improvements, details, and uses can be made consistent with the letter and spirit of the foregoing disclosure and within the scope of this patent, which is limited only by the following claims, construed in accordance with the patent law, including the doctrine of equivalents.
What is claimed is:

Claims

1. A highly, filled composition, comprising: a polymeric material;
at least one filler, and at least one surface active agent;
wherein one of the surface active agent, or filler has an overall pH greater than or equal to 7 and the other of the surface active agent or filler has an overall pH less than or equal to 7, provided that both overall pH's do not equal 7, the pH
relationship between the surface active agent and filler enhancing the filler loading of the
composition.
2. The highly, filled composition of claim 1 wherein the polymeric material, includes a thermoset polymer.
3. The highly, filled composition of claim 2 wherein the composition further comprises a
photoinitiator.
4. The highly, filled composition of claim 2 wherein the polymeric material includes a prepolymer,
5. The highly, filled composition of claim 4 wherein the prepolymer is an aromatic epoxy acrylate,
6. The highly, filled composition of claim 5 wherein the aromatic epoxy acrylate is a diacrylate ester of bisphenol A epoxy.
7. The highly, filled composition of claim 4 wherein the polymeric material includes a monomer.
8. The highly, filled composition of claim 7 wherein the monomer is selected from the group consisting of trimethylol propane triacrylate, 1, 6 hexanediol diacrylate, dicyclopentenylacrylate, hydroxypropyl acrylate, and dimethylaminoethyl acrylate.
9. The highly, filled composition of claim 3 wherein the photoinitiator is selected from the group consisting of 2-isopropyl-thioxanthone, 2-2
dimethoxy-2, phenylacetophenone, 2-hydroxy-2
methyl-1-phenyl propan-1-one, 2-ethylhexyl
p-(N,N-dimethylamino) benzoate, and 2-(dimethyl amino) ethyl benzoate.
10. The highly, filled composition of claim 1 wherein the polymeric material includes a
thermoplastic polymer.
11. The highly, filled composition of claim 10 wherein the composition further comprises a solvent.
12. The highly, filled composition of claim 11 wherein the thermoplastic polymer is selected from the group consisting of polyvinylbutryate and
n-butylpolymethacrylate.
13. The highly, filled composition of claim 11 or 12 wh rein the solvent is selected from the group consisting of methylethylketone, toluene, isopropyl alcohol and xylene.
14. The highly, filled composition of claim 1, 2 or 10 wherein the filler is selected from the group consisting of calcium metasilicate, titanium dioxide and zinc sulfide.
15. The highly, filled composition of claim 1, 2 or 10 wherein the composition contains two surface active agents.
16. The highly, filled composition of claim 1, 2, 10 or 11 wherein the composition contains two fillers.
17. The highly, filled composition of claim 1, 2 or 11 wherein one of the surface active agents is an organic phosphate ester.
18. The highly, filled composition of claim 1, 2 or 10 wherein the filler used has been precoated with a surface active agent.
19. The highly, filled composition of claim 18 wherein the precoated filler is calcium metasilicate and the surface active agent is silane.
20. The highly, filled composition of claim 19 wherein the silane is methacryloxy propyltrimethoxy- silane.
21. The highly, filled composition of claim 13 wherein the organic phosphate acid ester is selected from the group of nonyl nonoxynol-7-phosphate, nonyl nonoxynol-10-phosphate, nonyl nonoxynol-15-phosphate, nonoxynol-9-phosphate, nonoxynol-4-phosphate,
trideceth-6-phosphate, trideceth-4-phosphate,
trideceth-7-phosphate, polyoxyethylene lauryl ether phosphate, polyoxyethylene phenyl ether phosphate, isoamyl alcohol ethoxylated phosphate,
polyoxyethylene butoxyethyl ether phosphate,
polyoxyethylene hexyl ether phosphate, oleic acid, palmitic acid and stearic acid.
22. The highly, filled composition of claim 1, 2 or 10 wherein the filler is carbon black.
23. The highly, filled composition of claim 1, 2 or 10 wherein the filler is an alloy of
chromium/copper/manganese/molybelenum, or
cobalt/chromium/aluminum/or chromium/cobalt/magnesium/aluminum or chromium/iron/silicon, or mickel/tin/titanium.
24. The highly, filled composition of claim 1, 2 or 10 wherein the filler is selected from the group consisting of copper, aluminum, iron oxide, silver, gold, palladium, platinum, iridium, tin, lead, cobalt, iron, magnesium, silicon, nickel, manganese, chromium, tungsten and titanium.
25. The highly, filled composition of claim 1, 2 or 10 wherein the surface active agent is a
quaternary ammonium salt.
26. The highly, filled composition of claim 1, 2 or 10 wherein the filler is calcium metasilicate and the surface active agent is silane.
27. The highly, filled composition of claim 1, 2 or 10 wherein the filler is calcium metasilicate and the surface active agent is an organic phosphate ester.
28. The highly, filled composition of claim 1 or 10 wherein the filler is calcium metasilicate and the surface active agent is an organic acid and/or alcohol.
29. The highly, filled composition of claim 1, 2 or 10 wherein the filler is carbon black and the surface active agent is an quaternary ammonium salt, alcohol or combination thereof.
30. The highly, filled composition of claim 1, 2 or 10 wherein the filler is a metal alloy and the surface active agent is a quaternary ammonium salt, alcohol, or combinations thereof.
31. The highly, filled composition of claim 1, 2 or 10 wherein the composition further comprises a flame retardant component.
32. The highly, filled composition of claim 1, 2 or 10 wherein the composition further comprises an inhibitor component.
33. The highly, filled composition of claim 1, 2 or 10 wherein the composition further comprises a thixotropic agent.
34. A highly, filled composition, comprising: a polymeric material;
at least one filler, and at least one surface active agent;
wherein the volume % of filler in the composition is sufficiently high to impart durability into a coating formed from the composition.
35. The highly, filled composition of claim 34 wherein the polymeric material includes a thermoset polymer.
36. The highly, filled composition of claim 34 wherein the polymeric material includes a
thermoplastic polymer.
37. The highly, filled composition of claim 35 or 36 wherein the volume % filler is greater than about 50.
38. The highly, filled composition of claim 37 wherein the volume % filler is greater than about 60.
39. The highly, filled composition of claim 38 wherein the volume % of filler is greater than about 75.
40. The highly, filled composition of claim 39 wherein the volume % of filler is greater than about 90.
41. A method of preparing a highly, filled composition, comprising:
selecting a polymeric material;
selecting at least one filler having a first overall pH;
selecting at least one surface active agent having a second overall pH; and
mixing the polymeric material,
filler(s) and surface active agent(s) forming a highly, filled composition, whereby one of the first and second overall pH's is greater than or equal to 7 and the other of the first and second overall pH's is less than or equal to 7 provided that both overall pH's do not equal 7.
42. The method of claim 41 wherein the polymeric material includes a thermoset polymer.
43. The method of claim 41 wherein the polymeric material includes a thermoplastic polymer.
44. The method of claim 42 or 43 wherein the filler has been pretreated with a surface active agent.
45. An electrical or electronic component coated with a composition as claimed in any one of claims 1, 2, 10 and 34.
46. A substrate painted with ink having a composition as claimed in any one of claims 1, 2, 10 or 34.
PCT/US1992/006116 1992-07-22 1992-07-22 Highly filled polymeric compositions WO1994002540A1 (en)

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US10676571B2 (en) 2013-12-02 2020-06-09 Sabic Global Technologies B.V. Polyetherimides with improved melt stability
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US7557139B2 (en) 2000-10-02 2009-07-07 Emory University Triptolide analogs for the treatment of autoimmune and inflammatory disorders
US8193249B2 (en) 2000-10-02 2012-06-05 Emory University Triptolide analogs for the treatment of autoimmune and inflammatory disorders
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