CA1341099C - Structures exhibiting improved transmission of ultrahigh frequency electromagnetic radiation and structural materials which allow their construction - Google Patents

Structures exhibiting improved transmission of ultrahigh frequency electromagnetic radiation and structural materials which allow their construction

Info

Publication number
CA1341099C
CA1341099C CA 609708 CA609708A CA1341099C CA 1341099 C CA1341099 C CA 1341099C CA 609708 CA609708 CA 609708 CA 609708 A CA609708 A CA 609708A CA 1341099 C CA1341099 C CA 1341099C
Authority
CA
Canada
Prior art keywords
resin
cyanate
weight percent
resins
adhesives
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Fee Related
Application number
CA 609708
Other languages
French (fr)
Inventor
Jack D. Boyd
Hermann Sitt
Hong-Son Ryang
Theodore Frank Biermann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cytec Technology Corp
Original Assignee
Cytec Technology Corp
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 Cytec Technology Corp filed Critical Cytec Technology Corp
Application granted granted Critical
Publication of CA1341099C publication Critical patent/CA1341099C/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/42Housings not intimately mechanically associated with radiating elements, e.g. radome
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/24Structurally defined web or sheet [e.g., overall dimension, etc.]
    • Y10T428/24149Honeycomb-like
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/29Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913Rod, strand, filament or fiber
    • Y10T428/2933Coated or with bond, impregnation or core
    • Y10T428/2938Coating on discrete and individual rods, strands or filaments
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/29Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913Rod, strand, filament or fiber
    • Y10T428/2933Coated or with bond, impregnation or core
    • Y10T428/2964Artificial fiber or filament
    • Y10T428/2967Synthetic resin or polymer
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/31551Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]
    • Y10T428/31605Next to free metal

Abstract

Radomes having increased transparency and reduced reflectivity and refractivity to radar waves may be prepared or repaired utilizing heat-curable resin-containing structural materials in which the heat-curable resin contains greater than about 70 weight percent of cyanate functional monomers. The structural materials take the form of matrix resin impregnated prepegs and composites, film adhesives, paste adhesives, syntactic foams, and expandable foams, and may be used to prepare numerous useful structural features including honeycomb materials and leading edge radomes containing syntactic foams.

Description

' STRUCTURES EXHIIBITING IMPROVED TRANSMISSION
OF ULTRAHIGH FREQCIENCY ELECTROMAGNETIC RADIATION
AND STRUCTURAL l~~IATERIALS WHICH ALLOW THEIR CONSTRUCTION
Ba;Ickground of the Invention 1. Field of the Invention The subject invention relates to structures exhibiting improved transmission of electromagnetic radia-tion in the radar wave region of the spectrum, and to structural materials which allow the construction of such structures.
2. Description of the Related Art Innumerable technological improvements in the amplification, signal conditioning and treatment, radiation and reception of electromagnetic radiation in the radar wave portion of the spectrum have been made since the inception of the use of radar in the 1930's, and extension of the range of operable .frequencies has been made well into the Ghz region. Howemer, because most radar antennae are enclosed, transmission of radar waves in the vicinity of the antenna is still p:roblem~atic.
The enclosure surrounding a radar antenna, regardless of its actual shape, is termed a radome. Radomes are strong, electrically transparent shells which provide protection of the ~intenn~a from meterological events, ~34i 09 9 especially wind and water. In the case of military radar, protection from concussive effects of nearby guns or the blast from near hits is also required. Some protection from ballistic energy is also required.
Radomes vary in size and shape from simple conical or parabolic housings whose diameters are measured in centimeters, to large dome shaped structures tens of meters in diameter. The construction methods and structural materials utilized in building radomes are equally varied.
Ideally, the pr~,nciple radome material should have the same transmission properties as air. However, this ideal cannot be achieved, and considerable losses in signal strength and changes in the wave envelope occur because of the electrical characteristics of the structural materials.
Due to large differences between the dielectric constants of the structural materials and air, reflections occur at the air/m,~terial interfaces, causing signal loss as well as complicating signal processing. In addition, due to the differences in geometric shape of the antenna and its radome, the variou;~ signal paths are generally not equal and thus refractance o:E the ,signal also occurs. Finally, the construction materials exhibit a power loss through absorp-tion of the signal. This absorption, quantified by the loss tangent, is roughly analogous to the phenomenon of electrical resistance in the transmission of current electricity, cause;a heating of the radome material, and is the basis for dielectric heating so commonly used in industry.
When radomes are constructed from fiber reinforced composites, epoxy ~~esins and bismaleimide matrix resins are generally used due to their excellent physical character-istics. Unfortunal=ely, 'the electrical characteristics of these materials arE~ far :Er.~m ideal. The fiber reinforcement in such applications generally consists of fibers spun from fused quartz, as these fibers have dielectric constants and loss tangents far better than ordinary glass fibers formed from borosilicate classes.
When radomes are constructed from honeycomb material, especial7.y common for large radomes, the outer, face-plies are generally a thin fiber reinforced composite prepared from epox~~ or bismaleimide impregnated heat-curable prepregs, while they honeycomb itself may be prepared from similar prepregs, from phenolic resin impregnated prepregs, or from extruded thermoplastics such as high temperature service polycarbona~tes or' polyimides. In this case, as with traditional fiber-reinforced composites, the resin systems utilized for forming the face plies and the honeycomb often do not have the desired electrical characteristics.
Moreover, the face sheets are adhesively joined to the honeycomb core thr~~ugh the use of film adhesives. In the past epoxy, bismal~eimide, and phenolic film adhesives have been used, and thus the film adhesives suffer from the same electrical drawbacks as the matrix resins used in the face plies. Moreover, many of these adhesives have less than the desired ability to bond to certain prepregging materials, particularly those prepared using bismaleimide matrix resins.
Ceramic rnateri~als have been utilized for small radomes, particular.-ly for missle applications. However it is well known that ceramic materials tend to be brittle and difficult to fabricate. When adhesives are utilized to bond ceramic constructs to themselves, to other parts of the radome structure, or to ithe missle or other base, once again epoxy and other connmon adhesives have been used, adhesives which have higher c9ielectric constants and greater loss than the ceramic materials they join.
_ q _ ~~'~~ X99 Sintered polytetrafluoroethylene (PTFE) powders and fibers have been used in radomes due to their excellent electrical properties, as disclosed in U.S. patents 4,364,884 and 4,615,859. However, such structures are difficult to fabricate and lack the strength required for many military applications. PTFE fibers could be used in conjunction with epoxy or bismaleimide matrix resins, but would then suffer from the electrical disadvantages of these resins.
In U.S. patent 4,436,569, a protective cover for use with radomes or other aircraft structures is proposed in which a polyethylene/polyurethane composite is adhesively bonded to the underlying structure, preferably with a polyurethane adhesive. Unfortunately, the polyurethane polymer and adhesive have relatively low strength properties at elevated temperatures, as does also the polyethylene.
Bismaleimide-triazine resins have been proposed for use in electrical circuit boards by the Mitsubishi Gas Chemical Company, Inc., in their brochure entitled "BT
Resin". These resins contain difunctional monomers having a bismaleimide group as one of the functional groups, and a ~~410gg .
cyanate group as the other. However the reported dielectric constant is reported to be high, being greater than 4.2 at 1 Mhz. Thus these resins would not appear to have the low dielectric constant desired of a prepregging resin or adhesive based on this publication, and moreover, their electrical behavior in the radar region (>100 Mhz), is unknown.
In U.S. ;patent 4,353,769, a composite material for radomes is propose~3 in which Astroquartz~ fiber reinforcing fabric is impregnated with..a specific prepolymer made from ethyleneglycol, 4,~4'-methylenediphenylenediisocyanate, and 2,4-toluenediisocy~~nate. However the dielectric constants of these materials are still higher than desirable, and loss tangents are truly improved over only a narrow compositional range. Moreover, the cured prepreg lacks adequate high temperature performance due to the use of polyurethane as the matrix resin.
The use of high temperature polimides has been proposed for fiber reinforced radomes in supersonic applica-tions. See, for example, M. C. Cray, "High Performance Radome Manufacture Using Polyimides," Vol. l, p. 309-319, t 341 09 9 Proceedings, International Conference on Electromagnetic Windows, 3d. (1976), and T. Cook, "Supersonic Radomes in Composite Materials," Vol. 1, p. 4-1 to 4-14, Proceedings of the Third Technology Conference (1983). However thermo-setting polyimides are difficult to process, especially with regard to the formation of volatiles during cure, and thermoplastic polyimides require high temperature extrusion or pressure forming, which again renders their use problem-atic. Furthermore, it is difficult to formulate suitable adhesives from pol:yimides,_ particularly when the adherends are composites prepared from bismaleimide resin impregnated prepregs.
E-glass :reinforced PTFE and S-glass reinforced perfluoroepoxy resins have been proposed as candidates for radome application;; by E. A. Welsh, "Evaluation of Ablative Materials for High Performance Radome Applications,"
Symposium on Elect~romagn~etic Windows, 15th, p. 179-185, (1980). Reinforced PTFE is expensive and difficult to process, however; <~nd pe:rfluoroepaxy resins are both difficult to prepare as well as not being readily available.
_ 7 _ The use ~of a variety of thermoplastics including polyimides, polyamide-imides, polyphenylene sulfides, nylons, polyesters, and polyethersulfones, among them, has been proposed by R. A. Mayor in "Cost Effective High Performance Plastics for Millimeter Wave Radome Applica-tions," Proceedings, Twenty-Fourth National SAMPE Symposium, Book 2, p. 1567-15'91 (1979). However many of these materials, such as melt processable nylons and polyesters do not have the hightemperature capabilities desired, and the high performance thermoplastics such as the polyimides and polyethersulfones ~sre difficult to process. In addition, many of these thermoplastics have undesirably high di-electric constants and loss tangents.
In U.S. patent 4,568,603 is disclosed a fiber reinforced syntactic foam useful for lightweight structures such as microwave iaaveguides. However, as can be surmised from their intende<i use, these materials are microwave reflective rather l.han transparent. The use of epoxy resins in formulating such syntactic foams and the inclusion of graphitic or carbon fibers is in agreement with this conclu-sion. Thus the usE~ of such syntactic foams as adhesives, fillers, or as structural materials in radar applications requiring transparE~ncy, :is prohibited.
_ g _ ~34~ 099 Thus there exists a need for structural materials, particularly structural adhesives, which have low dielectric constants and low :Loss tangents in the radar region of the spectrum, and which also have superior strength, toughness, and adhesive qualities. Thus far such products have not been available to the industry.
Summary of the Invention An object ~of this invention is to provide radomes having increased transparency to radar waves. A
further object is to provide structural materials which are suitable for the construction of such radomes. These structural materials include heat-curable fiber reinforced prepregs, film adhesives, paste adhesives, and syntactic foams wherein the f~rinciple heat curable monomer is a di-or polycyanate resin. These materials have unexpectedly low dielectric constants and loss tangents at radar and microwave frequencies, and, in addition, possess exceptional physical properties at high temperatures.
More particularly, the invention as claimed hereinafter providesa process for the manufacture or repair of radomes in which matrix resins, structural adhesives, and foams containing heat curable resin systems are utilized, wherein use is made, as raid heat curable resin system, of a resin system comprising, in weight percent relative to the totale resin system weight, a) about 70 percent or more of a cyanate resin;
b) from 0 to about 25 weight percent of a bismaleimide resin; .
c) from 0 to about 20 weight percent of an epoxy resin, d) from 0 to about 20 weight percent of an engineering thermoplastic' selected from the group consisting of the polyimides, polyetherimides, and polyamideimides; and _ g _ ~341~99 e) an effective' amount of a cyanate cure promoting catalyst.
The invention also provides a syntactic foam having increased transparency to radar waves, comprising:
a) from 90 to about 40 weight percent of a heat curable resin system component, comprising:
i) about 70 weight percent or more of a heat curable c:yanate resin; and ii) an amount of a catalyst effective to cure said cyanate resin;
and from 10 to about 60 weight percent of b) a mic:rosphere component.
The invention further provides a heat-curable cyanate adhesive composition, comprising:
a) a cyanate functional monomer and/or prepolymer;
b) an epoxy functional polysiloxane; and c) an arr~ount of a catalyst effective to promote the elevated tempE~rature cure of said composition, wherein the loss tangent of the neat resin as measured by ASTM D2520 is less than about 0.007 at 25°C.
Description of the Preferred Embodiments The radomes of the subject invention are varied in both size, shape, and construction. In the case of radar in the X, K, and Q bands, the size may be a matter of a few A
- 9a -centimeters or tens of centimeters onl y, while in the P and K bands, the size may be as large as tens of meters. The construction of such radomes is well known to those skilled in the art. In addition to the articles previously cited, construction and design details of such radomes may be found in the following references; G. Tricoles, "Wave Propagation Through Hollow Dielectric Shells", NTIS HC A05/MF A01 (1978); H. Bertram, "The Development Phase, Design, Manufac-ture, and Quality Control of the MRCA-radome", vol. l,p.
329-349, Proceedings, International Conference or Electromagnetic Windows, 3d., (1976); C.A. Paez, "Radome Design/Fabrication Criteria for Supersonic EW Aircraft", p.
166-186, Proceedings. Tenth National SAMPE TPCt,n; r.ai Conference, (1978); K. B. Armstrong, "British Airways Experience with Composite Repairs", The Repair of Aircraft Structures Involving Com~~osite Materials, NTIS HC All/MF A01 (1986); J. B. Styron, "A Broadband Kevlar Radome for Shipboard", Part 2" p. 135-144, Proceedings, Symp. on Electromagnetic Windows 1( 7th, (1984); Chuang, C. A.
"Miniaturization TE~chniques Benefit Conformal Arrays", Microwaves and RF, vol. 23, March 1984, p. 87-92; L. M.
Poveromo, "Polyimiiie Composites-Grumman Application Case ~34~ Ogg Histories, "Proceeain s, 27th National Sampe Sym osium, (1982); H. Feldman, "Design of Variable Thickness Sandwich Radomes", p. 40-43, Proceedings, Symposium or Electro-magnetic Windows, 15th, (1980); D. Purinton, "Hroadband High Speed Reinforced P:Lastic Radome", p. 1-5, ~mposium on Electromagnetic Windows, 14th, (1978); R. Chesnut, "LAMPS
Radome Design", p. 21-23, ~mposium on Electromagnetic Windows, 13th (197ii); J. Peck, "Development of a Lower Cost Radome", Society oi' Automotive Engineers, SAE Paper 730310 (1973). Of course,, thes~e~are but a sampling of the many articles which deal with radome construction.
The radonnes of the subject invention exhibit high transparency to elE~ctromagnetic radiation in the radar region of the spectrum byr virtue of the use of matrix resins, film adhesives, syntactic foams, cellular adhesives, core splice adhesives, and paste adhesives which are heat-curable resin systems containing a majority of a cyanate-functional resin. This c:yanate functional resin may be a di-or polyfunctiona~l cyanate monomer of relatively low molecular weight, a~ di- or polyfunctional cyanate oligomer, or a relatively higiher me>lecular weight cyanate-functional prepolymer.

~~41 ~9 9 Thus one aspect of the subject invention concerns the use of one or more of the previously identified types of cyanate resin systems in the production of radomes; while a second, closely related aspect, are the radomes thusly produced. A further aspect of the subject invention relates to compositions of matter which may be utilized to prepare syntactic foams, cellular foams, and heat-curable adhesives and which exhibit auperior transparency to electromagnetic radiation in the microwave and radar regions of the spectrum. Finally, a stil3 further aspect of the subject invention relates ~to a novel process for the preparation of compositions suitable for cyanate-functional adhesives and prepregging resins..
By the tE~rm heat-curable resin system is meant a composition containing reactive monomers, oligomers, and/or prepolymers which will cure at a suitably elevated tempera-ture to an infusib7.e solid, and which composition contains not only the aforementioned monomers, oligomers, etc., but also such necessary and optional ingredients such as catalysts, co-monomers, Theology control agents, wetting agents, tackifiers, tougheners, plasticizers, fillers, dyes and pigments, and the li~:e, but devoid of microspheres or ~34~ 099 otrier "syntactic" fillers, continuous fiber reinforcement, whether woven, non-woven (random), or unidirectional, and likewise devoid of any carrier scrim material, whatever its nature. The heat-curable resin systems of the subject invention contain greater than about 70 weight percent of cyanate-functional monomers, oligomers. and/or prepolymers, not more than about 25 percent by weight of a bismaleimide comonomer, and optionally up to about 10 percent of an epoxy resin.
By the term "film adhesive" is meant a heat-curable film, which may be unsupported or supported by an optional carrier, ~~r scrim. Such films are generally strippably adhered to a release film which may be a poly-olefin film, a polyester film, or paper treated with a suitable release coating, for example a silicone coating.
Such film adhesive; are useful in joining metal and fiber reinforced composite adh~erends as well as adherends of other materials, such as wood, plastic, and ceramics. Certain film adhesives, for example those of the subject invention, may also be used as prep~egging matrix resins.
Hy the term "paste adhesive" is meant a heat-curable adhesive which ins semisolid or at least highly ~34~ X99 viscous or thixotr~~pic in nature, in order that it may be spread upon the adlaerends with suitable tools, for example brushes, spatulas, and trowels, and will remain upon the surface until the ~?arts .are cured. Such adhesives generally contain a greater proportion of fillers and thickeners than other adhesives, but of .course do not contain a carrier web. Curing of the paste adhesives of the subject invention paste adhesives is achieved at 177°C.
By the term "s;yntactic foam" is meant a heat-curable resin systE~m which.. contains an appreciable volume percent of preformE~d hollow beads or "microspheres". Such foams are of relat:lvely :low density, and generally contain from 10 to about 60 weight percent of microspheres, and have a density, upon cure, of from about 0.50 g/cm3 to about 1.1 g/cm3 and preferabT~.y have' loss tangents at 10 Ghz as measured by ASTM D 2520 of 0.008 or less. The microspheres may consist of glass, fused silica, or organic polymer, and range in diameter ):rom 5 to about 200 um, preferably about 150 ym, and have de~nsitie~s of from about 0.1 g/cm3 to about 0.4 g/cm3 to about 0.4 g,~cm3. The syntatic foams are cured at 177°C.

By the term "foam adhesive" or "expandable adhesive" is meant a heat-curable adhesive containing a blowing agent such that the cured adhesive contains numerous open or closed cells whose walls consist of the cured adhe-sive itself. Hybrid adhesives containing both microspheres (as in syntactic foams) .and adhesive-walled cells are also contemplated. The blowing agent may be a liquid of suitable volatility or an organic or inorganic compound which decomposes into at least one gaseous component at elevated temperature, for example, p,p-oxybisbenzenesulfonyl hydra-zide. Many other :such b:iowing agents are known to those skilled in the art..
Hy the tearm "matrix resin" is meant a heat-curable resin system which comprises the major part of the contin-uous phase of the impregnating resin of a continuous fiber-reinforced prepreg or composite. Such impregnating resins may also contain other reainforcing media, such as whiskers, microfibers, short chopped fibers, or microspheres. Such matrix resins are used to impregnate the primary fiber reinforcement at levels of between 10 and 70 weight percent, generally from 30 to 40 weight percent. Both solution and/or melt impregnation techniques may be used to prepare fiber reinforced preprega containing such matrix resins.
The matrix resins nnay also be used with chopped fibers as the major fiber reinforcement, for example, where pultrusion techniques are involved.
In the mainufact:ure of radomes having improved transparency to waves in the radar region of the spectrum, i.e. frequencies of from about 100 Mhz to about 100 Ghz, conventional methods of design and/or construction are used, except that the cya,nate resin systems of the subject invention will replace they'traditional epoxy, bismaleimide, phenolic or other heat-curable resins in one or more, and preferably all, of their respective areas of application.
In other words, it is preferable when utilizing honeycomb materials having fiber reinforced epoxy or bismaleimide resin face plies, that analogous face plies containing a cyanate functional resin will be utilized instead, and that cyanate adhesives will be used to bond the face plies to the honeycomb rather than the conventional epoxy, bismaleimide, or phenolic resins. Even the honeycomb itself may be formed from cyanate impregnated Astroquartzm, polyolefin, or PTFE fibers.

~34~ X99 When preparing radomes using either chopped or conventional continuous fiber reinforced heat curable resins, the cyanate matrix resins of the subject invention may replace analogous epoxy and bismaleimide resins. When it is desired to use syntactic foams as adhesives, fillers, or load bearing members, the cyanate functional syntactic foams of the subject invention may replace syntactic foams containing other heat curable resins. Of course, the low loss, low dielectric constant products of the invention may also be useful in ~electrortic applications requiring such properties, particularly when cyanates such as bis[4-cyanato-3,5-dimeth;ylphen;yl] methane are used.
The various cy~anate resin systems of the subject invention contain :in excess of about 70 weight percent of cyanate functional monomers, oligomers, or prepolymers, about 25 weight pe~~cent or less of bismaleimide comonomer, and up to about 10 weight percent of epoxy comonomer, together with from 0.000:1 to about 5.0 weight percent catalyst, and optionally, up to about 10 percent by weight of engineering thermoplaa~tic. In addition to these compon-ents, individual formulai:ions may require the addition of minor amounts of fillers" tackifiers, etc.

?34~ X99 ' Cyanate resins are heat-curable,resins whose reactive functionality is the cyanate, or -OCN group. These resins are genera lly prepared by reacting a di- or poly-functional phenolic compound with a cyanogen halide, generally cyanogen chloride or cyanogen bromide. The method of synthesis by nosy is well known to those skilled in the art, and examples may be found in U.S. patents 3,448,079, 3,553,244, and 3,7~~0,348. The products of this reaction are the di- and polycyanate esters of the phenols.
The cyanate eslter prepolymers useful in the compositions of the' subject invention may be prepared by the heat treatment of c;yanate functional monomers either with or without a catalyst. The degree of polymerization may be followed by measurement of the viscosity. When catalysts are used to assist the polymerization, tin catalysts, e.g.
tin octoate, are preferred. Such prepolymers are known to the art.
Suitable cyanat:e resins may be prepared from mono, di-, and polynuclear phenols, including those containing fused aromatic structures. They phenols may optionally be sub-stituted with a wide variety of organic radicals including, but not limited to halogen, nitro, phenoxy, acyloxy, acyl, ~34~ ~99 cy~no, alkyl, aryl, alkaryl, cycloalkyl, and the like.
Alkyl substituents may be halogenated, particularly per-chlorinated and perfluorinated. Particularly preferred alkyl substituents are methyl and trifluoromethyl.
Particularly preferred phenols are the mononuclear diphenols such as hydroquinone and resorcinol; the various bisphenols such as bisphenol A, bisphenol F, bisphenol K, and bisphenol S; t:he various dihydroxynaphthalenes; and the oligomeric phenol .and cresol derived novolacs. Substituted varieties of these phenols-are also preferred. Other preferred phenols are the phenolated dicyclopentadiene oligomers prepared by the Friedel-Crafts addition of phenol or a substituted phenol to dicyclopentadiene as taught in U.S. patent 3,536,')34.
Bismaleirnide resins are heat-curable resins containing the maleimido group as the reactive function-ality. The term busmale:imide as used herein includes mono-, bis-, tris-, tetra4;is-, and higher functional maleimides and their mixtures as yell, unless otherwise noted. Bismale-imide resins with an average functionality of about two are preferred. Bismale~imide resins as thusly defined are prepared by the reaction of malefic anhydride or a sub-.
stituted malefic anlaydrid~e such as methylmaleic anhydride, with an aromatic oar alipihatic di- or polyamine. Examples of the synthesis may he found, for example, in U.S. patents 3,018,290, 3,018.2!2, 3,627,780, 3,770,691, and 3,839,358.
The closely related nadic imide resins, prepared analogously from a di- or polyamine but wherein the malefic anhydride is substituted by a Diels-Alder reaction product of malefic anhydride or a sub:.tituted malefic anhydride with a diene such as cyclopentadiene, are also useful. As used herein and in the claims, the term bismaleimide resin shall include the nadic imide re:cins a7lso.
Preferred di- and polyamine precursors include aliphatic and aromatic di.amines. The aliphatic diamines may be straight chain, branched, or cyclic, and may contain heteroatoms. Many examples of such aliphatic diamines may be found in the above cited references. Especially prefer-red aliphatic diamines are hexanediamine, octanediamine, decanediamine, dodecanedi.amine,.and trimethylhexanediamine.
The aromatic diamines may be mononuclear or polynuclear, and may contain fused ring systems as well.
Preferred aromatic diamines are the phenylenediamines; the toluenediamines: the various methylenedianilines, partic-ularly 4,4'-methylenedianiline; the naphthalenediamines; the various amino-terminated polyarylene oligomers corresponding to or analogous to the formula:
H2N-Ar[X-ArjnNH2 wherein each Ar may individually be a mono-or polynuclear arylene radical, each X may individually be O O O O
-O-~ -S-~ -C-. -S-, -0-C-, -O-C-O, . C1-C10 lower O
alkyl, and C2-C10 lower alkyleneoxy, or polyoxyalkylene; and wherein n is an integer of from about 1 to 10; and primary aminoalkyl terminated di-,and polysiloxanes.
Particularly useful are bismaleimide "eutectic"
resin mixtures containing several bismaleimides. Such mixtures generally have ;melting points which are consider-ably lower than th~~ individual bismaleimides. Examples of such mixtures may lbe found in U.S. patents 4,413,107 and 4,377,657. Several such eutectic mixtures are commercially available.
Epoxy resins are thermosetting resins containing the oxirane, or ep~~xy group, as the reactive function-ality. The oxirane group may be derived from a number of ~34~ X99 diverse methods of synthesis, for example by the reaction of an unsaturated compound with a peroxygen compound such as peracetic acid; or by the reaction of epichlorohydrin with a compound having an active hydrogen, followed by dehydrohalo-genation. Methods of synthesis are well known to those skilled in the art, and may be found, for example, in the Aandbook of Epoxy ;Resins, Lee and Neville, Ed. s., McGraw-Hill, 0 1967, in chapters 1 and 2 and in the references cited therein.
The epoxy resins-useful in the practice of the subject invention ~~re substantially di- or polyfunctional resins. In general, the functionality should be from about 1.8 to about 8. Many such resins are available commer-cially. Particularly useful are the epoxy resins which are derived from epich:lorohydrin. Examples of such resins are the di- and polygl;,rcidyl derivatives of the bisphenols, particularly bisphenol A, bisphenol F, bisphenol K and bisphenol S; the d:ihydro:Kynaphthalenes, for example 1,4-, 1,6-, 1,7-, 2,5-, ;t,6-, and 2,7-dihydroxynaphthalenes; 9,9-bis[4-hydroxypheny:l]fluo;rene; the phenolated and cresolated monomers and oligorners of dicyclopentadiene as taught by U.S. patent 3,536,',134 ; the aminophenols, particularly 4-aminophenol; various amines such as 4,4'-, 2,4'-, and 3,3'-methylenedianiline and analogs of methylenedianiline in which the methylene group is replaced with a C1-C4 substi-tuted or unsubstituted lower alkyl, or -O-, -S-, -CO-, -O-CO-, -O-CO-O-, -S02-, or aryl group; and both amino, hydroxy, and mixed amino and hydroxy terminated polyarylene oligomers having -~0-, -S-, -CO-, -O-CO-, -O-CO-0-, -S02-, and/or lower alkyl groups interspersed between mono or polynuclear aryl groups as taught in U.S. patent 4,175,175.
Also suitable ar-a the epoxy resins based on the cresol and phenol novolacs. The novolacs are prepared by the condensation of phenol or cresol with formaldehyde, and typically have more than two hydroxyl groups per molecule.
The glycidyl derivatives of the novolacs may be liquid, semisolid, or solid, and generally have epoxy functional-ities of from 2.2 to about B.
Also useful are epoxy functional polysiloxanes.
These may be prepared by a number of methods, for example by the hexachloroplatinic acid catalyzed reaction of allyl-glycidyl ether witlh dimethylchlorosilane followed by hydrolysis to the Ibis-substituted disiloxane. These materials may be equilibration polymerized to higher moYecular weights by reaction with a cyclic polysiloxane such as octamethylc:yclot~etrasiloxane. Preparation of the epoxy functional polysiloxanes is well known to those skilled in the art., Useful epoxy functional polysiloxanes have molecular weights from about 200 Daltons to about 50,000 Daltons, prE~ferab:ly to about 10,000 Daltons.
Suitable thermoplastic tougheners are high tensile strength, high gla:os transition polymers which fit within the class of compo:~ition:a known as engineering thermo-plastics. If more than ~~-5 weight percent of such thermo-plastics are used i.n the compositions of the subject invention, then their elE~ctrical properties become important. In thi:~ case,. the thermoplastic, fully imidized polyimides, polyetr~erimic~es, polyesterimides, and polyamide-imides are preferred. Such products are well known, and are readily commercially available. Examples are MATRIMIDm 5218, a polyimide available from the Ciba-Geigy Co., TORLONm, a polyamif~eimide~ available from the Amoco Co., ULTEMm, a polyetherimide available from the General Electric Co., and KAPTONm, a polyertherimide available from the DuPont Company. Such polyimides; generally have molecular weights above 10,000 Daltons, preferably above 30,000 Daltons.

Also suitable are the various soluble polyarylene polymers containing substituted and unsubstituted lower alkyl, -CO-, -CO-O-, -S-, -0-, -O-CO-O, and -S02- inter-spersed between the arylene groups, as taught in U.S. patent 4,175,175. Particularly preferred are the polyetherether-ketones, polyetherl~cetones, polyetherketoneketones, poly-ketonesulfones, po:lyethersulfones, polyetherethersulfones, and polyetherketon~~sulfones. Several of such polyarylene polymers are comme:rciall;y available.
It is ne~:essar;y -that the thermoplastic be capable of dissolution into the remaining resin system components during their preparation. However, it is not necessary that this solubility be maintained during cure, so that the thermoplastic may phase out during cure. The order of mixing the thermop:Lastic containing prepregs of the subject invention is most :important. Surprisingly, the mere mixing together of the ingredients does not afford a useful composition when cyanate prepolymers are used. In this case, solution of t:he po:Lyimide may be obtained by first preparing a subasseambly consisting of the polyimide dis-solved in either tt~e bisrnaleimide component, when the latter is used, or into cyanate functional monomer.

Suitable catalysts for the cyanate resin systems of the subject invention are well known to those skilled in the art, and include the various transition metal carboxy-lates and naphthen~ates, for example zinc octoate, tin octoate, dibutylti;ndilaurate, cobalt naphthenate, and the like; tertiary amines such as benzyldimethylamine and N-methylmorpholine; imidaz~oles such as 2-methylimidazole;
acetylacetonates such as iron(III) acetylacetonate; organic peroxides such as dicumylperoxide and benzoylperoxide; free radical generators such ~as~azobisisobutyronitrile; organo-phoshines and orgaoophos~phonium salts such as hexyldiphenyl-phosphine, triphen~~rlphos~phine, trioctylphosphine, ethyltri-phenylphosphonium .'iodide and ethyltriphenylphosphonium bromide; and metal complexes such as copper bis[8-hydroxy-quinolate]. Combination:; of these and other catalysts may also be used.
Preferrei9 reiniEorcing fibers, where such fibers are used, include fiberglass, polyolefin, and PTFE. Other types of fiber reir~forcernent may also be used, particularly those with low dielectric: constants. When fiberglass is used, it is preferable that the fibers be greater than 90 weight percent pure: silica. Most preferably, fused silica fillers are used. .Such fibers are commercially available under the name AST;ROQUARTZm, a trademark of the J.P. Stevens Company.
Polyolefin fibers are also preferred. High strength polyolefin fibers are available from Allied-Signal Corporation under the tr~adename SPECTRAm polyethylene fiber. Such fiber;; have a dielectric constant of approxi-mately 2.3 as compared t~o values from 4-7 for glass and about 3.75 for fused silica.
The examples wlhi-Eh follow will serve to illustrate the practice of this inmention, but are in no way intended to limit its appli~:ation. The parts referred to in the examples which follow arse by weight unless otherwise designated, and the temperatures are in degrees Celcius unless otherwise designated. In the claims, the term "adhesive" refers 1.o adhesives of all types previously identified, i.e. f:ilm adhesives, syntactic foam adhesives, paste adhesives, foam adhesives, and the like, unless more specifically identified.
Example 1 A cyanate-funcitional structural adhesive was prepared by mixing 200 parts by weight of bis[4-cyanato-3,5-~ 341 49 9 dimethylphenyl]methane and 60 parts of Compimide~353A, a eutectic mixture of bismaleimides believed to contain the bismaleimides of 4,~4'-diaminodiphenylmethane, 2,4-toluene-diamine, and 1,6-diaminotrimethylhexane, and which is avail-able from the Boots-Technochemie Co.. The mixture was heated and stirred <it 130'°C for one hour, following which 20 parts by weight of :gin epo:Ky-terminated polysiloxane and 0.2 part by weight of copper bis[8-hydroxyquinolate] catalyst was added. Adhesive' tapea were prepared by coating the mixture as a 15-20 nnil film on both sides of glass fabric.
Test specimens were cured for 4 hours at 177°C and post cured for 2 hours at: 232°(:. Electrical properties of the neat resins are pre:~ented in Table I.
Example 2(Comparative) An attempt: was made to prepare a thermoplastic toughened cyanate functional adhesive by dissolving MATRIMIDm 5218, a frilly imidized thermoplastic polyimide available from the C'iba-Ge~igy Corporation and based on 5(6)-amino-1-(4'-aminophernyl)-7.,3-trimethylindane, into the pre-polymer derived from bis[4-cyanato-3,5-dimethylphenyl]-methane. However, solution could not be effected.

.. '._ ... _ .

1 341 O9 g ' Example 3 Into 17.~D parts by weight of bis[4-cyanato-3,5-dimethylphenyl]methane was slowly added 4.25 parts of Matrimid~' 5218. The mixture was heated to 150°C to effect solution of the po:lyimid~e. Next, 19.7 parts Compimidem 353A
was heated to 150°1~ in a mixing vessel, following which the previously prepared cyan,ate/polyimide was added. After complete solution :is obtained, 53.0 parts of bis[4-cyanato-3,5-dimethylphenyl]methane prepolymer was added, mixed for 20 minutes, and cooled to 120°C, at which time 2.7 parts hydrophillic silic<3 (CAB~~SILmM5) was added, and the composi-tion stirred under vacuum for 60 minutes. The mixture was then cooled to 79°c~ and 10.22 parts of copper bis[8-hydroxy-quinolate] dissolved in 3.1 part of DENm 431 epoxy resin, a product of the Dow Chemical Company was added. This material was then east a;s a film and coated onto glass fiber for use as a strucl:ural adhesive.
Exarnples ~4 and 5 (Comparative Structur~~l adhesives were prepared by coating commercial epoxy (Example 4) and bismaleimide (Example 5) adhesives onto a g7lass fiber support as in Examples 1 and 3. Electrical prod>ertiea were measured over the 10-12.5 Ghz ~34~ 099 range. The results of the cured, neat resin testing are summarized below i:n Table I.
_ 3o _ Table I

Examples ConditionDielectric Constant Loss Tangent 25C 2.74 0.005 149C 2.75 0.007 232C 2.76 0.009 3 25C 2.8 0.002 204C 2.81 0.003 4b 25C 3.07 0.008 (Comparative) 25C 2.95 0.007 (Comparative) 2.96 0.008 aneat resin bEpoxy decomposest,emperat,ures of c.a.and above at 204C

Examp7Le 6 (Comparative A composition was prepared and coated in accor-dance with Example 1 but without the epoxy functional polysiloxane. The composition contained 80 parts bis(4-cyanato-3,5-dimeth;ylphenyl]methane, 100 parts Compimide~
353A bismaleimide resin, and 0.2 parts copper bis(8-hydroxy-quinolate) catalyst.

Adhesives from Examples 1 and 3'and Comparative Example 6 were subjected to physical testing, the results of which are summarized in Table II. As can be seen, the subject invention formulations not only possess the excel-lent electrical characteristics portrayed in Table I, but also are exceptional high performance structural adhesives. Table II also indicates that the adhesive from Comparative Example 6 lacks the strength exhibited by the subject invention .adhesives.

f 34f X99 ' Table II
Tensil~s Lap Shear Strengthd Test Temperature/Condition Adhesive from Example 1 3a 3b 6 25°C (dry) 2680 4700 - 1270 25°C (wet)c - 3600 2540 -191°C(wet)c - 2800 3200 -204°C(dry) 3670 - - 1827 232°(dry) - 2000 - -a. adherend=bismaleimide/glass fabric laminates 0.20 inch thick (.51 cm) b. adherend=2024 T3 Aluminum c. hot/wet bond strength after 72 hour water boil d. ASTM D1002 ' Example 7 A honeycomb core structural material was prepared by laminating two 4 layer (0°/90°)2 carbon fiber (Hercules AS4) uncured face plies to a 12.5 mm thick aluminum honeycomb having a 3.2 mm cell size, by means of two 40 mil films of the adhesive of Example 3. The assembly, under 30 psi pressure, was ramped at 1.7°C/minute to 120°C where it was held for 1 hour, following which the tempera-ture was raised to 177°C: for 6 hours. Thus the face plies and adhesive were cocured. The assembly was post cured for 2 hours at 227°C and 1 hour at 250°C. The flatwise tensile strength (ASTM
C297) was 980 psi at 25°C, 840 psi at 204°C, and 610 psi at 232°C.
Example 8 Syntactic foams were prepared by mixing together at 130°C
for 2 hours 7.5 parts of bis[4-cyanato-3,5-dimethylphenyl]methane, 67.9 parts of a commercial cyanate resin based on phenolated dicyclopentadiene, and from 15 to 40 weight percent, based on total composition weight, of glass microspheres. Following cooling to 90°C, .105 part of copper bis[8-hydroxyquinoline) dissolved in 1.5 parts of DENm 431 epoxy resin was added. The foams were cured at 177°C. Electrical and physical properties of the cured foams are presented in Table III.

~ ~ N N O

L 0 .? ~ N

~ O

V7 t~~N .- ~ ,_ w ~ ~

Or .- .- ~ N
C

O

dl W

d ~i ~ M ~

~ N ~ ~ ~ N

, N

U

U "i O

ri ri N 0r!

O
O a r- , 4~

C .? vD vG LL1tf1lf1 tf1 ~ O

H o 0 o g ' 0 o o "

o O o o O o O no, o o m a U

L

'O
O ' G

O

U

~ ~ ~ ~

U 00 ~ ~ C O

s. N .-,...r- ~ ~ r- ~ y y a~

'~ ~ o co .., r., v n~ a ~

a, "'i s. o H E

U

\ v _ ~ U
N W ~ ~ ~ A

D ~ 1 e~
u O O O O O O O

U

a m A

~..~ cb dt c c.. a~

v E
a~

d d v v v ~ v ~

c a a ~ .
\ \ \ \ U c \ U O
O 0D 00 00 00 \ 00 \ O r-1 -I

M M M

M N M
DO

~ O O O O O O O c0 00 W i..

U

C

d a N V

07 v .r O

t N _ 8 " Ca N M ~ M N M ~

r1 ed o a ~

a c.

U

.1 c0 ~ U

'341099 Example 9 A paste .adhesive was prepared as follows. At 150°C, 23 parts by weight of ERLm 4221 cycloaliphatic epoxy resin available from the Union Carbide Corporation, 50 parts of a cyan,ate ester resin based on phenolated dicyclopentadiene .and available from the Dow Chemical Company as Dow XU7:1787.02 resin, and 20 parts of bis[4-cyanato-3,5-dimeth:Ylphenyl]methane was combined with 5.0 parts of MATRIMIDm 5218. The mixture was stirred for a period of from 4-6 hours until a homogenous solution was obtained whereupon 4.0 parts of silicon dioxide filler (CABOSILm M5) was added .and stirred until fully dispersed.
After cooling to 90°C, 0.1 parts of copper bis[8-hydroxyquinolate] c9issolved in 3.0 parts of an epoxy novolac resin was added. '.the pa;ste adhesive was stored at -18°C
until use.
Example 10 An expanc9able lEoam adhesive was prepared by mixing, at 150°C, 70 parts by weight of bis(4-cyanato-3,5-dimethylphenyl]methane and 5.0 parts of Matrimid 5218 polyimide. The mixture was stirred for from 4-6 hours until homogenous whereupon 20 parts of a eutectic mixture of bismaleimide resins, COMPIMIDEm 353, was added. Following solution of the bi;smalei;mide, 3.0 parts of CABOSIL M5 was dispersed into the mixture. After cooling to 90°C, 0.1 part copper bis[8-hydro:Kyquin~olatej and 0.2 part p,p-oxybis-benzenesulfonyl hynrazid~e (CELOGENm OT, a product of Uniroyal), both di:~solve~d in 3.0 part of epoxy novolac resin, was added. The adhesive was then cast as a 50 mil thick film and sor~~ed at -18°C prior to use.
Example 11 The composition of Example 3 was coated onto ASTROQUARTZm 503 for use as a prepreg. A 12.5 mm thick composite was prep~ired bay laying up approximately 50 plies of fabric into an :isotropic [0°, 90°j25 layup and curing at 177°C. Electrical properties of the cured composite were measured at lOGhz and are presented below in Table III.
T~L1~ TTT
Temp Dielectric Constant Loss Tangert 25°C 3.26 0.002 204°C 3.25 0.004 f 341 ~9 9 Example 12 A leading edge radome is prepared by laying up Astroquartzm fabric, impregnated with a matrix resin system whose cyanate resin content is approximately 80 weight percent, into the ~9esired exterior and interior configura-tions. The interior space is filled with a syntactic foam prepared as in Example 8 and having a 20 weight percent microsphere loading and .a density of 0.74 g/cm3. The finished radome ha:a considerably enhanced radar wave transmission properties over otherwise similar radomes prepared using epo:~y and,/or bismaleimide resins instead of cyanate resins.
Example 13 A large shipboard type radome is prepared from honeycomb core structural material. The honeycomb material is prepared by lam9W ating two exterior face plies and one internal ply to two extruded polyimide honeycombs each 2.54 cm thick. The facE~ plies are prepared by impregnating Astroquartz fabric (0,90")2 with c.a. 35 weight percent of a matrix resin similar to that of Example 12. At the inter-faces between the exterior face plies and the honeycomb and also between the two honeycomb layers and the internal ply ~~~1099 are layed up the cyanate structural adhesive of Example 3.
The layup is pressure bay3ged to 30 psi and cured as in Example 7. The resulting two layer honeycomb structure has increased transparE~ncy to radar waves as well as lower reflection and refraction than similar radomes prepared using epoxy or bismaleim:ide structural materials in the place of one or more of i=he above applications containing cyanate resins.
Example 14 A radome protec:t-ive cover of a polyethylene composite is adhesi.vely fastened to a radome as in U.S.
patent 4,436,569, lout the' cyanate adhesive of Example 3 is used. The cover shows increased adhesion even at 232°C
while having excellent transparency to radar waves.
Example 15 In a manner similar to that of Example 8, a syntactic foam was prepared employing 8.2 parts bis[4-cyanato-3,5-dimethylphenyl)methane, 65.9 parts of a commercial cyanate resin based on phenolated dicyclopentadiene, and catalysed with 0.2 parts copper bis[8-hydroxyquinoline) dlissolved in 2.6 parts DEN~ 431 epoxy resin. Microsphere~s having a density of 0.2 g/cm3 were added at a 23.1 percent by weight level.

Claims (10)

1. In a process for the manufacture or repair of radomes in which matrix resins, structural adhesives, and foams containing heat curable resin systems are utilized, the improvement comprising employing as said heat curable resin system, a resin system comprising, in weight percent relative to the totale resin system weight, a) about 70 percent or more of a cyanate resin;
b) from 0 to about 25 weight percent of a bismaleimide resin;
c) from 0 to about 20 weight percent of an epoxy resin, d) from 0 to about 20 weight percent of an engineering thermoplastic selected from the group consisting of the polyimides, polyetherimides, and polyamideimides; and e) an effective amount of a cyanate cure promoting catalyst.
2. A radome prepared by the process of claim 1.
3. A syntactic foam having increased transparency to radar waves, comprising:
a) from 90 to about 40 weight percent of a heat curable resin system component, comprising:
i) about 70 weight percent or more of a heat curable cyanate resin; and ii) an amount of a catalyst effective to cure said cyanate resin;
and from 10 to about 60 weight percent of b) a microsphere component.
4. The syntactic foam of claim 3, wherein said resin system component (a) comprises in excess of 90 weight percent cyanate resin.
5. The syntactic foam of claim 3, wherein said microspheres comprise borosilicate glass or fused quartz microspheres.
6. The syntactic foam of claim 3, wherein the loss tangent at 10 Ghz is less than about 0.008 as measured in accordance with ASTM D2520.
7. A heat-curable cyanate adhesive composition, comprising:
a) a cyanate functional monomer and/or prepolymer;
b) an epoxy functional polysiloxane; and c) an amount of a catalyst effective to promote the elevated temperature cure of said composition, wherein the loss tangent of the neat resin as measured by ASTM D2520 is less than about 0.007 at 25°C.
8. The adhesive composition of claim 7, which is a paste adhesive.
9. The adhesive composition of claim 7, further comprising a blowing agent.
10. The adhesive composition of claim 8, further comprising a blowing agent.
CA 609708 1988-08-29 1989-08-29 Structures exhibiting improved transmission of ultrahigh frequency electromagnetic radiation and structural materials which allow their construction Expired - Fee Related CA1341099C (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US07/238,021 US4956393A (en) 1988-08-29 1988-08-29 Structures exhibiting improved transmission of ultrahigh frequency electromagnetic radiation and structural materials which allow their construction
US07/238,021 1988-08-29

Publications (1)

Publication Number Publication Date
CA1341099C true CA1341099C (en) 2000-09-19

Family

ID=22896160

Family Applications (1)

Application Number Title Priority Date Filing Date
CA 609708 Expired - Fee Related CA1341099C (en) 1988-08-29 1989-08-29 Structures exhibiting improved transmission of ultrahigh frequency electromagnetic radiation and structural materials which allow their construction

Country Status (6)

Country Link
US (1) US4956393A (en)
EP (1) EP0357006B1 (en)
JP (1) JPH02177602A (en)
CA (1) CA1341099C (en)
DE (1) DE68912991T2 (en)
ES (1) ES2049785T3 (en)

Families Citing this family (41)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5139843A (en) * 1988-11-24 1992-08-18 Tonen Kabushiki Kaisha Elongated lightweight fiber reinforced composite resin pultrusion-formed piece
US5184141A (en) * 1990-04-05 1993-02-02 Vought Aircraft Company Structurally-embedded electronics assembly
US5077319A (en) * 1990-05-18 1991-12-31 Hexcel Corporation Cyanate resin-based foams
US5212495A (en) * 1990-07-25 1993-05-18 Teleco Oilfield Services Inc. Composite shell for protecting an antenna of a formation evaluation tool
JP2687805B2 (en) * 1991-03-29 1997-12-08 松下電工株式会社 Resin composition, prepreg and laminated board
US5182155A (en) * 1991-04-15 1993-01-26 Itt Corporation Radome structure providing high ballistic protection with low signal loss
US5296280A (en) * 1991-11-25 1994-03-22 E. I. Du Pont De Nemours And Company Process for making a honeycomb core from a honeycomb half-cell structure and honeycomb core made thereby
DE69304086T2 (en) * 1992-01-07 1997-04-03 Hitachi Chemical Co Ltd Polyimides, thermosetting resin compositions with the polyimides, moldings on the resin compositions and processes for producing their polyimides
CA2077125C (en) * 1992-01-13 2002-04-09 Louis B. Brydon Self-supporting convex cover for spacecraft
US5338594A (en) * 1992-02-07 1994-08-16 Hexcel Corporation Foam filled honeycomb and methods for their production
WO1993017860A1 (en) * 1992-03-13 1993-09-16 Rogers Corporation Cyanate ester microwave circuit material
US5405107A (en) * 1992-09-10 1995-04-11 Bruno; Joseph W. Radar transmitting structures
FR2711845B1 (en) * 1993-10-28 1995-11-24 France Telecom Planar antenna and method for producing such an antenna.
US5494981A (en) * 1995-03-03 1996-02-27 Minnesota Mining And Manufacturing Company Epoxy-cyanate ester compositions that form interpenetrating networks via a Bronsted acid
US5837739A (en) * 1995-06-07 1998-11-17 Mcdonnell Douglas Corporation Loaded syntactic foam-core material
US5665787A (en) * 1995-06-07 1997-09-09 Mcdonnell Douglas Corporation Loaded syntactic foam-core material
US5707723A (en) * 1996-02-16 1998-01-13 Mcdonnell Douglas Technologies, Inc. Multilayer radome structure and its fabrication
FR2752835B1 (en) * 1996-09-05 1999-05-07 Ctmi Cotton Textiles Pour Mate CERAMIC COMPOSITE MATERIAL WITH SANDWICH-TYPE STRUCTURE
US5912316A (en) * 1996-11-08 1999-06-15 Johnson Matthey, Inc. Flexible interpenetrating networks formed by epoxy-cyanate ester compositions via a polyamide
US6028565A (en) * 1996-11-19 2000-02-22 Norton Performance Plastics Corporation W-band and X-band radome wall
US6350513B1 (en) 1997-10-08 2002-02-26 Mcdonnell Douglas Helicopter Company Low density structures having radar absorbing characteristics
US6146484A (en) * 1998-05-21 2000-11-14 Northrop Grumman Corporation Continuous honeycomb lay-up process
US6406783B1 (en) 1998-07-15 2002-06-18 Mcdonnell Douglas Helicopter, Co. Bulk absorber and process for manufacturing same
US6132546A (en) * 1999-01-07 2000-10-17 Northrop Grumman Corporation Method for manufacturing honeycomb material
DE69924509T2 (en) * 1999-05-21 2006-02-16 The Government Of The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration (Nasa) POLYIMID MICROHOLE BALLS
CN1098879C (en) * 2000-03-14 2003-01-15 复旦大学 Polyetherimide modified bimalieimide resin
DE10117979A1 (en) * 2001-01-05 2002-08-14 Fraunhofer Ges Forschung Microwave heated molding tool for manufacture of plastic components, is made from triazine and/or cyanate polymers
US6811418B2 (en) * 2002-05-16 2004-11-02 Homac Mfg. Company Electrical connector with anti-flashover configuration and associated methods
US7205043B1 (en) * 2004-08-09 2007-04-17 The United States Of America As Represented By The Secretary Of The Navy Pressure resistant anechoic coating for undersea platforms
US7901535B2 (en) * 2005-02-23 2011-03-08 Teh Yor Co., Ltd. Apparatus and method for making cellular shade material
CN100482718C (en) * 2006-01-26 2009-04-29 长春应化特种工程塑料有限公司 Polyimide semi-interpenetrating network resin and its prepn. method
CN100410325C (en) * 2006-01-26 2008-08-13 广东生益科技股份有限公司 Resin composition and its use in bonding sheet and copper clad plate
FR2946179B1 (en) * 2009-05-29 2012-11-30 Saint Gobain Quartz Sas DIELECTRIC TAPE PREIMPREGNE FOR RADOME
EP2756548A1 (en) * 2011-09-12 2014-07-23 DSM IP Assets B.V. Composite radome wall
JP5900258B2 (en) * 2012-09-11 2016-04-06 株式会社デンソー Epoxy resin production method and curable epoxy resin composition
CN103074027A (en) * 2013-01-11 2013-05-01 西北工业大学 Phenolphthalein cyanate/benzoxazine resin adhesive resistant to 250 DEG C and preparation method
CN108485592A (en) * 2018-03-23 2018-09-04 黑龙江省科学院石油化学研究院 A kind of long-term resistance to 300 DEG C of paper honeycombs core bar adhesive and preparation method thereof
US11637367B2 (en) 2018-04-06 2023-04-25 3M Innovative Properties Company Gradient permittivity film
FR3082667B1 (en) * 2018-06-14 2021-06-11 Dassault Aviat RADOME INCLUDING A LAMINATED STRUCTURE INCLUDING COMPOSITE LAYERS WHOSE FIBER REINFORCEMENT IS CONSISTING OF POLYOLEFIN FIBERS
CN111786102A (en) * 2019-04-03 2020-10-16 莱尔德电子材料(深圳)有限公司 Low-dielectric and low-loss antenna housing
CN112250989A (en) * 2020-11-05 2021-01-22 成都佳驰电子科技有限公司 Wave-absorbing slurry and preparation method of honeycomb wave-absorbing material

Family Cites Families (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3002190A (en) * 1955-04-15 1961-09-26 Zenith Plastics Company Multiple sandwich broad band radome
DE1248668B (en) * 1963-02-16 1967-08-31 Farbenfabriken Bayer Aktienge Seilschaft Leverkusen Process for the preparation of aromatic cyano acid esters
NL6609886A (en) * 1966-07-14 1968-01-15
US4110364A (en) * 1974-03-19 1978-08-29 Mitsubishi Gas Chemical Company, Inc. Curable resin compositions of cyanate esters
JPS5610529A (en) * 1979-07-09 1981-02-03 Mitsubishi Gas Chem Co Inc Curable resin composition
JPS5626911A (en) * 1979-08-08 1981-03-16 Mitsubishi Gas Chem Co Inc Curable resin composition
JPS5626951A (en) * 1979-08-08 1981-03-16 Mitsubishi Gas Chem Co Inc Curable resin composition
JPS5698221A (en) * 1980-01-07 1981-08-07 Mitsubishi Gas Chem Co Inc Curable resin composition
US4396745A (en) * 1980-05-08 1983-08-02 Mitsubishi Gas Chemical Company, Inc. Curable resin composition
US4364884A (en) * 1980-05-15 1982-12-21 Rogers Corporation Method of manufacturing a radome
US4353769A (en) * 1980-10-03 1982-10-12 Lee Henry J Radar transparent rigid polyurethane laminate systems for radomes
US4615859A (en) * 1981-05-13 1986-10-07 Rogers Corporation Method of manufacture of improved radome structure
US4436569A (en) * 1981-09-21 1984-03-13 The United States Of America As Represented By The Secretary Of The Navy Method for forming a protective cover for aircraft having conical radomes
US4645805A (en) * 1984-03-14 1987-02-24 Mitsubishi Gas Chemical Company, Inc. Adhesive composition and adhesive film or sheet on which the composition is coated
DE3410501C2 (en) * 1984-03-22 1990-09-13 Dornier System Gmbh, 7990 Friedrichshafen Radome material
US4568603A (en) * 1984-05-11 1986-02-04 Oldham Susan L Fiber-reinforced syntactic foam composites prepared from polyglycidyl aromatic amine and polycarboxylic acid anhydride
CA1242796A (en) * 1984-10-12 1988-10-04 Yoshihiro Kitsuda Microwave plane antenna
US4731420A (en) * 1986-02-24 1988-03-15 The Dow Chemical Company Co-oligomerization product of a mixed cyanate and a polymaleimide and epoxy resin thereof
US4777226A (en) * 1986-06-12 1988-10-11 Allied Corporation Terpolymer from (1) a poly(vinylbenzylether) of a polyphenol (2) a cyanate ester of a polyphenol and (3) alkenyl aryl compound
US4709008A (en) * 1986-06-30 1987-11-24 Interez, Inc. Blend of tris (cyanatophenyl) alkane and bis(cyanatophenyl) alkane
US4774316A (en) * 1986-08-15 1988-09-27 The Dow Chemical Company Copolymer of vinylbenzyl ether of polyhydric halogenated phenolic compound and aromatic polycyanate ester compound
US4740584A (en) * 1986-09-08 1988-04-26 Interez, Inc. Blend of dicyanate esters of dihydric phenols
EP0266986A3 (en) * 1986-11-06 1989-09-06 Amoco Corporation Resin compositions comprising aromatic cyanate esters, polyepoxide compounds and thermplastic polymers and prepreg made therefrom
US4876153A (en) * 1987-04-09 1989-10-24 Basf Corporation Process for the preparation of cyanate resin-based prepregs and films which maintain their tack
US4785075A (en) * 1987-07-27 1988-11-15 Interez, Inc. Metal acetylacetonate/alkylphenol curing catalyst for polycyanate esters of polyhydric phenols

Also Published As

Publication number Publication date
EP0357006B1 (en) 1994-02-09
EP0357006A1 (en) 1990-03-07
DE68912991T2 (en) 1994-06-01
JPH02177602A (en) 1990-07-10
DE68912991D1 (en) 1994-03-24
ES2049785T3 (en) 1994-05-01
US4956393A (en) 1990-09-11

Similar Documents

Publication Publication Date Title
CA1341099C (en) Structures exhibiting improved transmission of ultrahigh frequency electromagnetic radiation and structural materials which allow their construction
US5134421A (en) Structures exhibiting improved transmission of ultrahigh frequency electromagnetic radiation and structural materials which allow their construction
KR102455920B1 (en) Resin composition, support with resin layer, prepreg, laminated board, multilayer printed wiring board, and printed wiring board for millimeter wave radar
AU634615B2 (en) Thermosettable resin composition containing resin particles
CA1235990A (en) High impact strength fiber resin matrix composites
JP2016131243A (en) Resin film, resin film with support, prepreg, metal-clad laminated sheet for high multilayer, and high multilayer printed wiring board
WO2014210236A1 (en) Cyanate resin blends and radomes including them
TWI745627B (en) Thermal-curable resin composition, and pre-preg, metal-clad laminate and printed circuit board manufactured using the same
US5434226A (en) Epoxy resin toughened with a polyether sulfone and polyarylsulfidesulfone
JPH11323087A (en) Reinforced thermosetting structural material
JP2016204639A (en) Resin composition, laminate and multilayer printed board
JP2016131244A (en) Resin film, resin film with support, prepreg, metal-clad laminated sheet and multilayer printed wiring board
US5167870A (en) Structures exhibiting improved transmission of ultrahigh frequency electromagnetic radiation and structural materials which allow their construction
EP0266986A2 (en) Resin compositions comprising aromatic cyanate esters, polyepoxide compounds and thermplastic polymers and prepreg made therefrom
US5021519A (en) Epoxy-polyimide blend for low temperature cure, high-performance resin system and composites
JPH01279964A (en) Thermosetting resin composition
Shimp Technologically driven applications for cyanate ester resins
EP0486044A2 (en) Damage tolerant composites containing infusible particles
JP2012193322A (en) Prepreg, and carbon fiber-reinforced composite material
JPH01129084A (en) Heat-curable epoxy resin adhesive
Wilson Polyimides as resin matrices for advanced composites
WO2015103427A1 (en) Composites for protecting signal transmitters/receivers
US5003013A (en) Intermediate for composite of polymaleimide, polycyanate, epoxy resin and polyester
JP4159902B2 (en) Resin composition, prepreg and laminate
Juska et al. Matrix resins and fiber/matrix adhesion

Legal Events

Date Code Title Description
MKLA Lapsed