CA1245390A - Synergistic effect of metal flake and metal or metal coated fiber on emi shielding effectiveness of thermoplastics - Google Patents
Synergistic effect of metal flake and metal or metal coated fiber on emi shielding effectiveness of thermoplasticsInfo
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- CA1245390A CA1245390A CA000440432A CA440432A CA1245390A CA 1245390 A CA1245390 A CA 1245390A CA 000440432 A CA000440432 A CA 000440432A CA 440432 A CA440432 A CA 440432A CA 1245390 A CA1245390 A CA 1245390A
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Abstract
SYNERGISTIC EFFECT OF METAL FLAKE AND METAL
OR METAL COATED FIBRE ON EMI SHIELDING
EFFECTIVENESS OF THERMOPLASTICS
ABSTRACT OF THE DISCLOSURE
Conductive thermoplastic having high EMI shielding effectiveness comprise a thermplastic condensation polymer and incorporated therein a synergistic combination of metal flake and conductive metal or metal coated fiber.
OR METAL COATED FIBRE ON EMI SHIELDING
EFFECTIVENESS OF THERMOPLASTICS
ABSTRACT OF THE DISCLOSURE
Conductive thermoplastic having high EMI shielding effectiveness comprise a thermplastic condensation polymer and incorporated therein a synergistic combination of metal flake and conductive metal or metal coated fiber.
Description
l.Z~5390 - 1 - 8CV~4015 SYNERGISTIC EFFECT OF M~TAL FLAKE AND METAL OR METAL
COATED FIBER ON EMI SHIELDING EFFECTIVENESS OF
_ THERMOPLASmICS
.
1. Field of the Invention The present invention is concerned with thermo plastic compositions having high electromagnetic/radio frequency interference (EMI/~FI) shielding effective-ness as a result of the incorporation therein of asynergistic combination of conductive me~al filler~.O
More specifically, thermoplastic polymers having high EMI/RFI shielding effectiveness may be prepared by incorporating therein a synergis~ic combination o 10 metal flake and metal or metal coated .iber.
Electronic equipment, particularly sensitive electronic equipment such as computers, business machines, communications equipment a.nd the like are all susceptible to malfunction as a result of EMI/RFI.
Furthermore, in addition to being sensitive to foreign EMI/RFI, many of these electronic devices generate EMI/RFI. During the early years of the electronic age, EMI/RFI shielding of electronic equipment was accomplished by conductive metallic housings.
How~ver, with the boom in the use of non-conductive plastic materials in the electronic industry, particu-: larly as sturdy, lightweight housings, EMI/RFI has : . become a great problem~ .
Much research has.been undertaken to provide : 25 .plastic housings ha~ing EMI/RFI shielding effective-nes~. Until recently, EMI/~FI shielding effectiveness in plastics was accomplished by conductive coatlngs, metallization, and plating of mold~d plastic parts.
These methods, while effective, are ccstly and labor intensive in that they require substantial am~unts of material and involve secondar~ operations in preparing the final product.
~, *
r` 1 : -~2~5390
COATED FIBER ON EMI SHIELDING EFFECTIVENESS OF
_ THERMOPLASmICS
.
1. Field of the Invention The present invention is concerned with thermo plastic compositions having high electromagnetic/radio frequency interference (EMI/~FI) shielding effective-ness as a result of the incorporation therein of asynergistic combination of conductive me~al filler~.O
More specifically, thermoplastic polymers having high EMI/RFI shielding effectiveness may be prepared by incorporating therein a synergis~ic combination o 10 metal flake and metal or metal coated .iber.
Electronic equipment, particularly sensitive electronic equipment such as computers, business machines, communications equipment a.nd the like are all susceptible to malfunction as a result of EMI/RFI.
Furthermore, in addition to being sensitive to foreign EMI/RFI, many of these electronic devices generate EMI/RFI. During the early years of the electronic age, EMI/RFI shielding of electronic equipment was accomplished by conductive metallic housings.
How~ver, with the boom in the use of non-conductive plastic materials in the electronic industry, particu-: larly as sturdy, lightweight housings, EMI/RFI has : . become a great problem~ .
Much research has.been undertaken to provide : 25 .plastic housings ha~ing EMI/RFI shielding effective-nes~. Until recently, EMI/~FI shielding effectiveness in plastics was accomplished by conductive coatlngs, metallization, and plating of mold~d plastic parts.
These methods, while effective, are ccstly and labor intensive in that they require substantial am~unts of material and involve secondar~ operations in preparing the final product.
~, *
r` 1 : -~2~5390
- 2 - 8CV-4015 Recently, attempts have been made to prepare conductive plastics by incorporating in engineering thermoplastics certain conductive fillers.
Specifically, these fillers include conductive powders, flakes and fibers. Generallyr approximately 25 - 40% by wt. conductive powder, 36 - 49% by wt.
conductive 1ake or 25 - 30% by wt. (in extruded parts, 3 - 6% in injection molded parts) c~nductive fiber must be incorporated into plastic materials in order to obtain EMI/RFI shielding. (Materials Engineering, March, 1982, P. 37 - 43; Modern Plastics International, September,-1982, P. 46 - 49).
.
More recently, attempts have been made to find synexgistic combinations O r conductive fillers so as to provide eYtrudable and moldable (e.g. by injection molding, blow-molding, RIM, transfer moldinq and the like) compounds having consistent shielding at lower loadings which maintain properties in the finished part and are economical to make. Such combinations have included mixtures of flaXe and powder and mixtures of metallized glass fiber and carbon fibers.
Canadian Patent Application, Ser-al Number 412,186, filed Septémber ~4, l9B2~ discloses the use of aluminum flake and/or carbon fiber or a combination of either of them with carbon black powder.
SU~RY
It has now been found that improved EMI/RFI
shielding effectiveness can be obtained in thermo-plastic polymer compositions by incorporating therein the synergistic combination of metal flake and metal or metal coated fibers. Further, it has bee~ found that the improved EMI/RFI shielding effectiveness may be enhanced even more by the use of said synergistic combination of mietal flake and metal or metal coated iber in polymer blends. The compositions of this . ., . ~
: ~
.~
` ~L2~539~
~ 3 ~ 8CV-4015 invention m~y be directly injection molded or extruded and molded and still retain high E~iI/RFI shielding effectiveness.
Specifically, the present invention concerns thermoplastic compositions having high E~lI/RFI shield-ing effectiveness comprising (a) one or more thermo-plastic polymers; (b) from zbout 25 to about 50% by wt., preferably from about 25 to about 40% ~y wt., based on the total composition, of metal flake and (c) from about 2 to about 12% by wt., preferably from about 4 to about 8~ by wt., based on the total compo-sition, of metal or metal coated fibers ~herein the weight ratio of metal flake to metal or metal coated fiber is from about 4:1 to about 14:1, prefera~ly from about 6:1 to about 10:1.
Preferred thermoplastic pol~mers`for which the invention is applicable include polyesters, polycar~
bonates, copolyestercarbonates, poiyamides, polyary-lene ether sulfones or ketones, polyamide imides, polyetherimides, polyphenylene ethers, polystyrenes, acrylonitrile butadiene styrene copolymers or blends thereof. These thermoplastic polymers may further comprise one or more addition polymers andlor one or more rubber or rubher modified thermoplastic resins.
Suitable metal flakes may be prepared from aluminum, copper, silver or nickel or alloys thereof.
~letal fibers may be selected from the group consisting of silver, copper, nickel, aluminum or stainless steel. The metal coated fibers comprise a base fiber of glass, graphite and the like upon which a metal coat of nickel, silver, copper or aluminum is applied.
The compositions may further comprise up to about 25~ of glass fibers for reinforcement and/or effective amounts of flame retardants.
The novel compositions of the present invention can be molded, foamed or extruded into vaxious structures or articles, especially electronic ~ . . . .
. ~ .
lZ~539~;) ~ 4 ~ 8CV-4015 equipment components and housings, requiring EMI
shielding and such structures or articles are included within the scope of this invention.
DESCRIPTION OF THE PREFERRED EMBOI)IMENTS
.
The present invention provides for thermoplastic compositions comprising a thermoplastic polymer or polymer blend and a synergistic combination of conductive metal flake and conductive metal or metal coated fibers to provide hish EMI/RFI shielding effectiveness. In order to realize said synergism, it is necessary to employ from about 25 to about 50%, - preferably from about 25 to about 40%, by wt., basèd on the total composition, of metal flake in combination with from about 2 to about 12%, preferably from about 4 to about 8%, by wt., based on the total composition of metal or metal coated fiber.
Furthermore, the weight ratio of flake to fiber should be from about 4:1 to 14:1, preferably from about 6:1 to about 10:1, to obtain the most cost ef~ective materials.
Metal flalses suitable for use in the compositions of the present invention include those prepared from the following metals or alloys thereof: silver, aluminum, nickel, copper and the like. Generally, said flakes have a thickness of less than about 0.005"
and surface dimension of less than about 0.10'l each.
Preferred flakes which have been found to be highly effective have an approY~imate size of 0.001" x 0.040"
x 0.060".
Additionally, the metal flakes may be treated with suitable coupling agents such as, for example, silane or titanate coupling agents, to improve processability and/or promote compatibility or bonding of the metal flakes to the thermoplastic resin.
Suitable metal flakes are a~ailable from a number of sources including Transmet Corp. of Columbus~ Ohio and Atlantic Powered Metals, Inc. of New York, New York.
~,`
:' . ~.
~Z~539(3 Metal and metal coated fibers useful in the present composition are more varied and widely avail-able. Generally, the metal fibers may be made of aluminu~, copper, silver, nickel, stainless steel and the like, and alloys thereof. Similarly, the metal coated fibers are generally of a graphite or glass core with a coating of silver, nickel, aluminum or copper and the like and alloys thereof. Sources of these fibers include Transmet Corp. of Columbus, Ohio;
M.B. Associates of San Ramon, Calif.; Bekaert Steel ~ire Corp. of Pittsburgh, Penn.; Brunswick Technetics of Deland, Fla; American Cyanamide of Wayne, N.Y.;
Nichimen America Inc of N.Y., ~I.Y.; and Lundy Electronics of Pompano Beach, Fla., among others.
Suitable fihers may be of essentially any length an~ diameter which is practical from both a composi-tion an~ processing standpoint, as known in the art.
For example, aluminum fibers measuring 6 mm in length by 90 ~icrons diameter are useful and practical, whereas stainless steel fibers of similar dimensions may be impractical and cause unnecessary wear on processing equipment: instead stainless steel fibers of 3 mm length by 4 microns diameter may be more suitable. Generally,`all suitable fibers will have a length of about 14 mm or less, preferably about 7 mm or less and a diameter of 0.2 mm or less, preferably of 0.1 mm or less. Once again, the actual dimensions of the fibers used depends in part on the composition or the fibers and their availability.
Additionallyl the fibers used in the present invention may be coated with any suitable sizing or coupling agents so as to improve processability as well as bonding and/or compatibility of the fibers and the thermoplastic material. Preferred coupling agents include those derived from silanes and titanates.
It is also possible, in accordance with the present invention, to use more than one type o~ metal ~ ~ . . . .
~Z~5390 - 6 - 8~V-4015 flake and/or fiber in the compositions of ~he present invention.
The aforementioned synergis~ic combination of conductive metal flake and metal or metal coated fiber S have improved EMI/RFI shielding over those employing only one conductive filler or a combination of conduc-tive fillers, as shown in the prior art, at the same level of incorporation. Thus the compositions pre-pared therefrom have reduced cost and better physical properties since less filler is added. Furthermore, these compositions avoid the problems associated with coatings, metallization and the lik;e with respect to being less labor intensive and time consuming to make the final product, more economical and devoid of the physical problems associated therewith including separation of the metal layer or coat from the plastic part.
The synergistic conductive filler combination is useful in most any thermoplastic polymer or polymer blend. Suitable prefe~red thermoplastic polymers include polyesters, polycarbonates, copolyestercarb-onates, polyamides, pol~arylene ether sulfones or ketonesl polyphenylene ethers, polyamide imides, polyetherimides, polystyrenes, acrylonitrile ~utadiene styrene copolymers or blends thereof. Further, it has been found that EMI/RFI shielding effectiveness of blends incorporating therein the synergistic conduc,ive filler combination often have even greater enhancement of EMI/RFI shielding than the single thermoplastic polymer alone.
(a) POLYESTERS
Suitable polyesters for the present invention are derived from one or more aliphatic and/or cycloaliph atic ~lycols and one or more aromatic dicarboxylic acids. The glycol may be selected from the group con-sisting essentially of ethylene ~lycol; 2 methyl-1,3 propanediol 1,4-butanediol; 1,5-pentanediol;
, .
/r - ~
~.,'2~S39(3 ~ 7 ~ 8CV-4015 1,6-hexanediol and 1,4-cyclohexanedimethanol, and the like. ~uitable dicarboxylic acids include terephthalic acid, phthalic acid, ~sophthalic acid and naphthalene ~,6-dicarboxylic acid. The polyesters of the present invention may also contain minor amounts of other units such as aliphatic dicarboxylic acids and/or aliphatic polyols to form copolyesters.
Generally, the polyesters of the present inven-tion may be represented by the ~ormula Il 10 - O ,1 C--O--- - R--OC ~
wherein R represents the divalent radical remaining after remova1 of the hydroxy groups from the glycol.
Preferred polyesters include poly~ethylene tere-phthalate), poly(butylene terephthala~e~ and blends thereof.
The polyesters described herein are either com-mercially available or can be produced by methods well known in the art, such as those set forth in United States PatentsNumbers 2,465,319; 3,047,539 -and 2,910,466. - Further, the polyesters used herein have an intrinsic viscosity of from about 0.4 to about 2.0 dl/g as measured in 60:40 phenol/tetra-chloroethane mixture or a similar solvent at 30C.
(b ) POLYCARBONATES
~ny of the polycarbonates known in the art may be used in accordance with the present invention. Espec-ially preferred polycarbonates are the aromatic poly-carbonates. ArGmatic polycarbonates useful herein are homopolymers, copolymers and mixtures thereof, which have an intrinsic viscosity o~ from about 0. to about 1.0 dl/g as measured in methylene chloxide at 25C.
Generally, the aromatic polycarbonates are ~; prepared by reacting a dihydric phenol with a carbon-atc pre~ursor su~h as phosgene, a haloformate or a , .
1;~45390 carbonate ester. Typical of the dihydric phenols that may be employed are 2,2-bis(4-hydroxyphenyl)propane;
bis(4-hydroxyphenyl)methane; 2,2-bis(4~hydroxy-
Specifically, these fillers include conductive powders, flakes and fibers. Generallyr approximately 25 - 40% by wt. conductive powder, 36 - 49% by wt.
conductive 1ake or 25 - 30% by wt. (in extruded parts, 3 - 6% in injection molded parts) c~nductive fiber must be incorporated into plastic materials in order to obtain EMI/RFI shielding. (Materials Engineering, March, 1982, P. 37 - 43; Modern Plastics International, September,-1982, P. 46 - 49).
.
More recently, attempts have been made to find synexgistic combinations O r conductive fillers so as to provide eYtrudable and moldable (e.g. by injection molding, blow-molding, RIM, transfer moldinq and the like) compounds having consistent shielding at lower loadings which maintain properties in the finished part and are economical to make. Such combinations have included mixtures of flaXe and powder and mixtures of metallized glass fiber and carbon fibers.
Canadian Patent Application, Ser-al Number 412,186, filed Septémber ~4, l9B2~ discloses the use of aluminum flake and/or carbon fiber or a combination of either of them with carbon black powder.
SU~RY
It has now been found that improved EMI/RFI
shielding effectiveness can be obtained in thermo-plastic polymer compositions by incorporating therein the synergistic combination of metal flake and metal or metal coated fibers. Further, it has bee~ found that the improved EMI/RFI shielding effectiveness may be enhanced even more by the use of said synergistic combination of mietal flake and metal or metal coated iber in polymer blends. The compositions of this . ., . ~
: ~
.~
` ~L2~539~
~ 3 ~ 8CV-4015 invention m~y be directly injection molded or extruded and molded and still retain high E~iI/RFI shielding effectiveness.
Specifically, the present invention concerns thermoplastic compositions having high E~lI/RFI shield-ing effectiveness comprising (a) one or more thermo-plastic polymers; (b) from zbout 25 to about 50% by wt., preferably from about 25 to about 40% ~y wt., based on the total composition, of metal flake and (c) from about 2 to about 12% by wt., preferably from about 4 to about 8~ by wt., based on the total compo-sition, of metal or metal coated fibers ~herein the weight ratio of metal flake to metal or metal coated fiber is from about 4:1 to about 14:1, prefera~ly from about 6:1 to about 10:1.
Preferred thermoplastic pol~mers`for which the invention is applicable include polyesters, polycar~
bonates, copolyestercarbonates, poiyamides, polyary-lene ether sulfones or ketones, polyamide imides, polyetherimides, polyphenylene ethers, polystyrenes, acrylonitrile butadiene styrene copolymers or blends thereof. These thermoplastic polymers may further comprise one or more addition polymers andlor one or more rubber or rubher modified thermoplastic resins.
Suitable metal flakes may be prepared from aluminum, copper, silver or nickel or alloys thereof.
~letal fibers may be selected from the group consisting of silver, copper, nickel, aluminum or stainless steel. The metal coated fibers comprise a base fiber of glass, graphite and the like upon which a metal coat of nickel, silver, copper or aluminum is applied.
The compositions may further comprise up to about 25~ of glass fibers for reinforcement and/or effective amounts of flame retardants.
The novel compositions of the present invention can be molded, foamed or extruded into vaxious structures or articles, especially electronic ~ . . . .
. ~ .
lZ~539~;) ~ 4 ~ 8CV-4015 equipment components and housings, requiring EMI
shielding and such structures or articles are included within the scope of this invention.
DESCRIPTION OF THE PREFERRED EMBOI)IMENTS
.
The present invention provides for thermoplastic compositions comprising a thermoplastic polymer or polymer blend and a synergistic combination of conductive metal flake and conductive metal or metal coated fibers to provide hish EMI/RFI shielding effectiveness. In order to realize said synergism, it is necessary to employ from about 25 to about 50%, - preferably from about 25 to about 40%, by wt., basèd on the total composition, of metal flake in combination with from about 2 to about 12%, preferably from about 4 to about 8%, by wt., based on the total composition of metal or metal coated fiber.
Furthermore, the weight ratio of flake to fiber should be from about 4:1 to 14:1, preferably from about 6:1 to about 10:1, to obtain the most cost ef~ective materials.
Metal flalses suitable for use in the compositions of the present invention include those prepared from the following metals or alloys thereof: silver, aluminum, nickel, copper and the like. Generally, said flakes have a thickness of less than about 0.005"
and surface dimension of less than about 0.10'l each.
Preferred flakes which have been found to be highly effective have an approY~imate size of 0.001" x 0.040"
x 0.060".
Additionally, the metal flakes may be treated with suitable coupling agents such as, for example, silane or titanate coupling agents, to improve processability and/or promote compatibility or bonding of the metal flakes to the thermoplastic resin.
Suitable metal flakes are a~ailable from a number of sources including Transmet Corp. of Columbus~ Ohio and Atlantic Powered Metals, Inc. of New York, New York.
~,`
:' . ~.
~Z~539(3 Metal and metal coated fibers useful in the present composition are more varied and widely avail-able. Generally, the metal fibers may be made of aluminu~, copper, silver, nickel, stainless steel and the like, and alloys thereof. Similarly, the metal coated fibers are generally of a graphite or glass core with a coating of silver, nickel, aluminum or copper and the like and alloys thereof. Sources of these fibers include Transmet Corp. of Columbus, Ohio;
M.B. Associates of San Ramon, Calif.; Bekaert Steel ~ire Corp. of Pittsburgh, Penn.; Brunswick Technetics of Deland, Fla; American Cyanamide of Wayne, N.Y.;
Nichimen America Inc of N.Y., ~I.Y.; and Lundy Electronics of Pompano Beach, Fla., among others.
Suitable fihers may be of essentially any length an~ diameter which is practical from both a composi-tion an~ processing standpoint, as known in the art.
For example, aluminum fibers measuring 6 mm in length by 90 ~icrons diameter are useful and practical, whereas stainless steel fibers of similar dimensions may be impractical and cause unnecessary wear on processing equipment: instead stainless steel fibers of 3 mm length by 4 microns diameter may be more suitable. Generally,`all suitable fibers will have a length of about 14 mm or less, preferably about 7 mm or less and a diameter of 0.2 mm or less, preferably of 0.1 mm or less. Once again, the actual dimensions of the fibers used depends in part on the composition or the fibers and their availability.
Additionallyl the fibers used in the present invention may be coated with any suitable sizing or coupling agents so as to improve processability as well as bonding and/or compatibility of the fibers and the thermoplastic material. Preferred coupling agents include those derived from silanes and titanates.
It is also possible, in accordance with the present invention, to use more than one type o~ metal ~ ~ . . . .
~Z~5390 - 6 - 8~V-4015 flake and/or fiber in the compositions of ~he present invention.
The aforementioned synergis~ic combination of conductive metal flake and metal or metal coated fiber S have improved EMI/RFI shielding over those employing only one conductive filler or a combination of conduc-tive fillers, as shown in the prior art, at the same level of incorporation. Thus the compositions pre-pared therefrom have reduced cost and better physical properties since less filler is added. Furthermore, these compositions avoid the problems associated with coatings, metallization and the lik;e with respect to being less labor intensive and time consuming to make the final product, more economical and devoid of the physical problems associated therewith including separation of the metal layer or coat from the plastic part.
The synergistic conductive filler combination is useful in most any thermoplastic polymer or polymer blend. Suitable prefe~red thermoplastic polymers include polyesters, polycarbonates, copolyestercarb-onates, polyamides, pol~arylene ether sulfones or ketonesl polyphenylene ethers, polyamide imides, polyetherimides, polystyrenes, acrylonitrile ~utadiene styrene copolymers or blends thereof. Further, it has been found that EMI/RFI shielding effectiveness of blends incorporating therein the synergistic conduc,ive filler combination often have even greater enhancement of EMI/RFI shielding than the single thermoplastic polymer alone.
(a) POLYESTERS
Suitable polyesters for the present invention are derived from one or more aliphatic and/or cycloaliph atic ~lycols and one or more aromatic dicarboxylic acids. The glycol may be selected from the group con-sisting essentially of ethylene ~lycol; 2 methyl-1,3 propanediol 1,4-butanediol; 1,5-pentanediol;
, .
/r - ~
~.,'2~S39(3 ~ 7 ~ 8CV-4015 1,6-hexanediol and 1,4-cyclohexanedimethanol, and the like. ~uitable dicarboxylic acids include terephthalic acid, phthalic acid, ~sophthalic acid and naphthalene ~,6-dicarboxylic acid. The polyesters of the present invention may also contain minor amounts of other units such as aliphatic dicarboxylic acids and/or aliphatic polyols to form copolyesters.
Generally, the polyesters of the present inven-tion may be represented by the ~ormula Il 10 - O ,1 C--O--- - R--OC ~
wherein R represents the divalent radical remaining after remova1 of the hydroxy groups from the glycol.
Preferred polyesters include poly~ethylene tere-phthalate), poly(butylene terephthala~e~ and blends thereof.
The polyesters described herein are either com-mercially available or can be produced by methods well known in the art, such as those set forth in United States PatentsNumbers 2,465,319; 3,047,539 -and 2,910,466. - Further, the polyesters used herein have an intrinsic viscosity of from about 0.4 to about 2.0 dl/g as measured in 60:40 phenol/tetra-chloroethane mixture or a similar solvent at 30C.
(b ) POLYCARBONATES
~ny of the polycarbonates known in the art may be used in accordance with the present invention. Espec-ially preferred polycarbonates are the aromatic poly-carbonates. ArGmatic polycarbonates useful herein are homopolymers, copolymers and mixtures thereof, which have an intrinsic viscosity o~ from about 0. to about 1.0 dl/g as measured in methylene chloxide at 25C.
Generally, the aromatic polycarbonates are ~; prepared by reacting a dihydric phenol with a carbon-atc pre~ursor su~h as phosgene, a haloformate or a , .
1;~45390 carbonate ester. Typical of the dihydric phenols that may be employed are 2,2-bis(4-hydroxyphenyl)propane;
bis(4-hydroxyphenyl)methane; 2,2-bis(4~hydroxy-
3-methylphenyl)propane; (3,3'-dichloro-4,4'-dihydroxy diphenyl)methane and the li~e. The aromatic poly-carbonates may be formed in accordance with the methods set forth in United States Patent Numb,ers , 2,999,835; 3,028,365; 2,999,844; 4,018,750 and
4,123,435, as well as other processes known to those skilled in ~he art.
The polycarbonates so produced, are typified as, possessing recur-ing structural units of the formuia O
_~- A _ o - C - -~-n wherein A is a divalent aromatic radical of the dihydric phenol employed in the polymer producing reaction and n is ~reater than one, preferably from about 10 to about 400.
It is of course possible to employ two or more dif~erent dihydric phenols or a dihydric phenol in combination with a slycol, a hydroxy or acid termin- -ated polyester, or a dibasic acid in the event a, carbonate copolymer or copolyester carbonate rather than a homopolymer polycarbonate is desired for use in the practice of th~ invention. Thus, it should be understood that the term "polycarbonate resin"
embraces within its scope carbonate co-polymers.
Suitable copolymers also include those poly-carbonate copolymers which comp~ise units derived from a first dihydric phenol which is a bis(hydroxyaryl)-sulfone and a second dihydric phenol such as2,2-bis~4-hydroxyphenyl)propane as disclosed in U.S.
Patent numbe~c 3,737,409; and 2,999,846.
~5390 ~ 9 - 8CV-4015 (c) POLYARYLE~E ~TE~ER SULF~ES OR KETONES
Polv(arylether) resin components suitable for use herein are linear, thermoplastic polyarylene polyether ~olysulfones, wherein the arylene units are inter-
The polycarbonates so produced, are typified as, possessing recur-ing structural units of the formuia O
_~- A _ o - C - -~-n wherein A is a divalent aromatic radical of the dihydric phenol employed in the polymer producing reaction and n is ~reater than one, preferably from about 10 to about 400.
It is of course possible to employ two or more dif~erent dihydric phenols or a dihydric phenol in combination with a slycol, a hydroxy or acid termin- -ated polyester, or a dibasic acid in the event a, carbonate copolymer or copolyester carbonate rather than a homopolymer polycarbonate is desired for use in the practice of th~ invention. Thus, it should be understood that the term "polycarbonate resin"
embraces within its scope carbonate co-polymers.
Suitable copolymers also include those poly-carbonate copolymers which comp~ise units derived from a first dihydric phenol which is a bis(hydroxyaryl)-sulfone and a second dihydric phenol such as2,2-bis~4-hydroxyphenyl)propane as disclosed in U.S.
Patent numbe~c 3,737,409; and 2,999,846.
~5390 ~ 9 - 8CV-4015 (c) POLYARYLE~E ~TE~ER SULF~ES OR KETONES
Polv(arylether) resin components suitable for use herein are linear, thermoplastic polyarylene polyether ~olysulfones, wherein the arylene units are inter-
5 spersed with ether and sulfone linkages. These resinsmay be obtained by the reaction of an alkali metal double salt of a dihydric phenol and a dihalobenzenoid compound, either or both of which contain a sulfone or ~etone lin~age i.e., - SO2 - or -CO- between arylene 10 groupings, to provide sulfone or ketone units in the polymer chain in addition to arylene units and ether units. The polysulfone polymer has basic structurè
comprising recurring units of the formula:
-O-E-O-E'-15 wherein E is the residuum of the dihydric phenol andE' is the residuum of the benzenoid compound having an inert electron withdrawing group in at least one of the positions ortho and para to the valence bonds;
both of said residua are valently bonded to the ether 20 oY.ygens through aromatic carbon atoms. Such polv~
sulfones are included within the class o~ polyarylene polyether resin described in, for example, United -~-States Patent Numbers 3,264,536 and 4,108,836.
The residuum of the dihydric phenol, E, is derived from dinuclear phenols having the stnlcture:
(I)n (ll)m OH-~- Ar - Rl - Ar-~-OH
wherein Ar is an aromatic group and preferably is a phenylene group, A and Al may be the same or different inert substituent groups, such a~ alkyl groups having from 1 to 4 carbon atoms halogen atoms or alkoxy radicals having from 1 to 4 carbon atoms, n and m are integers having a value of 0 to 4, inclusive, and R
is representative of a bond between aromatic carbon atoms as in dihydroxydiphenyl, or is a divalent radical including, for example, CO, O, S, S-S, SO2 or lZ45390 - 10 - ~CV-4015 a divalent or~anic hydrocarbon radicàl, such as alkylene, alkylidene,cycloalkyene, cycloalkylidene or the halogen, alkyl, or aryl or like substituted alkylene, alkylidene, cycloalkylene an~
cycloalkylidene radicals.
The polyarylene ether sulfones or ketones have a reduced viscosity of from about 0.4 to about 1.5 dl/g as measured in an appropriate solvent at a~ appro-priate temperature depending on the particular poly-ether, such as in methylenechloride at 25C. Thepreferred polyarylene ether sulfones or ketones have repeating units of the formula:
~'0 ~ SO2 ~
-+- O ~ C ~ and lS ~ O
(d) POLYAMIDES
Polyamides suitable for the presen~ invention may be obtained by polymerizing a monoaminomono-carboxylic acid or a lactam thereof having at least 2 carbon atoms between the amino and carboxylic acid group; or by polymerizing substantially equimolar proportions of . a diamine which contains at least 2 carbon atoms be-tween *he amino groups and a dicarboxylic acid; or by polymerizing a monoaminocarboxylic acid or a lactam thereof as defined above together with substantially equimolecular proportions of a diamine and a dicar~-oxylic acid. The dicarboxylic acid may be used in the form of a functional derivative thereof, far example an ester.
, , , .
~S3~0 ~ 8CV-4015 The term "substantially equimolecular" propor-tions (of the diamine and of the dicarboxylic acid) is used to cover both strict equimolecular proportions and slight departures therefrom which are involve~ in conventional techniques for stabilizing the viscosity of the resultant polyamides.
Examples of the aforementioned monoaminomonocar-boxylic acid~ or lactams thereof which are useful in preparing the polyamides include those compounds containing from 2 to 16 carbon atoms between the amino and carboxylic acid groups, said carbon atoms forming a ring with the -CO-NH- group in the case of a lactam.
As particular examples of aminocarboxylic acids and lactams there may be mentioned ~-aminocaproic acid, butyrolactam, pivalolactam, caprolactam, capryl-lactam, enantholactam, undecanolactam, dodecanol~ctam and 3- and 4- aminobenzoic acids.
Examples of diamines suitable for preparing the polyamides include diamines of the general formula 2 ( 2)n 2 wherein n is an integer of from 2 to 16, such as trimethylenediamine, tetramethylenediamine, penta methylenediamine, octamethylenediamine and especially hexamethylenediamine.
The dicarboxylic acids may be aromatic, for example isophthalic and terephthalic acids. Preferred dicarboxylic acids are of the formula HOOC-Y-COOH
wherein Y represents a divalent aliphatic radical con taining at least 2 carbon atoms, and examples of such acids are sebacic acid, octadecanedoic acid, suberic acid, glutaric acid, pimelic acid and adipic acid.
Preferred polyamides or nylons, as they are often called, include nylon 6, 6/6, 11, 12, 6/3, 6/4 and
comprising recurring units of the formula:
-O-E-O-E'-15 wherein E is the residuum of the dihydric phenol andE' is the residuum of the benzenoid compound having an inert electron withdrawing group in at least one of the positions ortho and para to the valence bonds;
both of said residua are valently bonded to the ether 20 oY.ygens through aromatic carbon atoms. Such polv~
sulfones are included within the class o~ polyarylene polyether resin described in, for example, United -~-States Patent Numbers 3,264,536 and 4,108,836.
The residuum of the dihydric phenol, E, is derived from dinuclear phenols having the stnlcture:
(I)n (ll)m OH-~- Ar - Rl - Ar-~-OH
wherein Ar is an aromatic group and preferably is a phenylene group, A and Al may be the same or different inert substituent groups, such a~ alkyl groups having from 1 to 4 carbon atoms halogen atoms or alkoxy radicals having from 1 to 4 carbon atoms, n and m are integers having a value of 0 to 4, inclusive, and R
is representative of a bond between aromatic carbon atoms as in dihydroxydiphenyl, or is a divalent radical including, for example, CO, O, S, S-S, SO2 or lZ45390 - 10 - ~CV-4015 a divalent or~anic hydrocarbon radicàl, such as alkylene, alkylidene,cycloalkyene, cycloalkylidene or the halogen, alkyl, or aryl or like substituted alkylene, alkylidene, cycloalkylene an~
cycloalkylidene radicals.
The polyarylene ether sulfones or ketones have a reduced viscosity of from about 0.4 to about 1.5 dl/g as measured in an appropriate solvent at a~ appro-priate temperature depending on the particular poly-ether, such as in methylenechloride at 25C. Thepreferred polyarylene ether sulfones or ketones have repeating units of the formula:
~'0 ~ SO2 ~
-+- O ~ C ~ and lS ~ O
(d) POLYAMIDES
Polyamides suitable for the presen~ invention may be obtained by polymerizing a monoaminomono-carboxylic acid or a lactam thereof having at least 2 carbon atoms between the amino and carboxylic acid group; or by polymerizing substantially equimolar proportions of . a diamine which contains at least 2 carbon atoms be-tween *he amino groups and a dicarboxylic acid; or by polymerizing a monoaminocarboxylic acid or a lactam thereof as defined above together with substantially equimolecular proportions of a diamine and a dicar~-oxylic acid. The dicarboxylic acid may be used in the form of a functional derivative thereof, far example an ester.
, , , .
~S3~0 ~ 8CV-4015 The term "substantially equimolecular" propor-tions (of the diamine and of the dicarboxylic acid) is used to cover both strict equimolecular proportions and slight departures therefrom which are involve~ in conventional techniques for stabilizing the viscosity of the resultant polyamides.
Examples of the aforementioned monoaminomonocar-boxylic acid~ or lactams thereof which are useful in preparing the polyamides include those compounds containing from 2 to 16 carbon atoms between the amino and carboxylic acid groups, said carbon atoms forming a ring with the -CO-NH- group in the case of a lactam.
As particular examples of aminocarboxylic acids and lactams there may be mentioned ~-aminocaproic acid, butyrolactam, pivalolactam, caprolactam, capryl-lactam, enantholactam, undecanolactam, dodecanol~ctam and 3- and 4- aminobenzoic acids.
Examples of diamines suitable for preparing the polyamides include diamines of the general formula 2 ( 2)n 2 wherein n is an integer of from 2 to 16, such as trimethylenediamine, tetramethylenediamine, penta methylenediamine, octamethylenediamine and especially hexamethylenediamine.
The dicarboxylic acids may be aromatic, for example isophthalic and terephthalic acids. Preferred dicarboxylic acids are of the formula HOOC-Y-COOH
wherein Y represents a divalent aliphatic radical con taining at least 2 carbon atoms, and examples of such acids are sebacic acid, octadecanedoic acid, suberic acid, glutaric acid, pimelic acid and adipic acid.
Preferred polyamides or nylons, as they are often called, include nylon 6, 6/6, 11, 12, 6/3, 6/4 and
6/12. The number avera~e molecular weights of the polyamides useful in the invention are generally a~ove about 10,000.
~2~53~30 (e) ~OLYAMIDE-I~5IDES
The polyamide-imide copolymers useful for the present invention generally ha~re a crystalline struc-ture and a melting point of over about 340C. They 5 are prepared by the reaction of dianhydrides with - diamines containing preformed amide groups resulting in an amide-imide structure as follows:
O O
\ ~ C C - NH N \ ~ N-~ ~ ~C~ .
Other copolymers can be prepared by the reaction of trimelletic anhydride acid chloride with aromatic diamines. These copolymers can be prepared by ths methods disclosed in Supplement Volume, Kirk - Othmer Encyclopedia of Chemical Technology, pages 746 ~ 773 (1971).
~f) POLYPHENYLE~E ETHER
The polyphenylene ether resins useful for the present invention comprise ho~opolymers and copolymers of structural units of the formula:
1~~
Q " Q' n wherein Q, Q', Q'' and Q' " are independently selected from the group consisting of hyflrogen, hydrocarbon radicals, halohydrocarbon radicals having at least 2 carbon atoms between the halogen atom and the phenyl nucleus, hydrocaxbonoxy radicals and halohydrocar-bonoxy radicals having at least 2 carbon atoms betweenthe halogen atom and phenyl nucleus, and Q', Q'' and Q''' in addition may be halogen with the provi~o that Q and Q' are both free of a tertiary carbon atom; and lZ45390 n represents the total number of monomer residues and is an interger of at least 50.
The preferred polyphenylene ether resin is a poly~2,6-dimethyl-1,4-phenylene)ether resin having an intrinsic viscosity of from about 0.3 dlJg to about 0.60 dl/g in chloroform. The polyphenylene ether resins useful herein are well known in the art and may be prepared from a number of catalytic and non-cata lytic processes from correspondiny phenols or reactive derivates thereof. Examples of polyphenylene ethers and methods for their production are disclosed in U.S.
Patent numbers 3,306,874; 3,306,875; 3,257,357 and 3,257,358.
(c? POLYETHERIMIDES
Polyetherimides useful for the present invention may be prepared from the reaction between sub-stantially equimolar amounts o' aromatic bis(ether anhydride)s of the formula, O - O
I O /\ ~ O-P~-O - ~ /O
ll ll O O
and organic diamine of the formula, I T
the reaction may take place in the prsence or absence of a solvent and/or catalytic agent or compound, as known in the art.
~s shown in formula I, R is a member selected from the class consisting of (a) the following divalent organic radicals:
' --- lZ4S39~
CH3 Cl'13 3 CH3 c~3 c~3 CH ~ Br Br ~ CH3 and 3 Br Br 3 Br Br C(CH3) Br Br and (b) divalent organic radicals of the general formula ( )m ~
where X is a member selected from the class consisting of divalent radicals of the formula O O
CyR2~ C-, -S-, -O-, -C(CH ) o and - S-, m is 0 or l, and y is a whole number from 1 to 5. R' as shown in formula II is a divalent organic rad.ical selected from the class consisting of (a) aromatic hydrocarbon radicals having from 6 - 20 carbon atoms and halogenated derivates thereof, ~b) 15 alkylene radicals, C(2 8) alkylene terminated polvdiorganosiloxan~, cvcloalkylene radicals having from 2 - 20 carbon atoms and (c) di~alent radicals included by the formula, ' ~2453~0 ~ (Q)m ~
where Q is a member selected from the class consisting ~f O O
~l , CXH2x- and -C(C~ ) and x is a whole number from 1 to 5 inclusive, and m is as previously defined. These polyetherimides are prepared by methods well known in the art such as those described in, for example~ U.S. Patent numbers 3,917,643; 3,~52,242; 3,855,176; 3,~33,546; 3,875,116;
3,83~,097; 3,905,942 and 3,933,719.
-,,~; .
(h) ACR'LONITRILE BUTADIENE STYRENE COPOLYMERS
In general, ABS type polymers contain two or more polymeric parts of different compositions which are 15 bonded chemically. The polymer is preferably prepared by polymerizing a conjugated diene, such as butadiene or a conjugated diene with a monomer copolymerizable therewith, ~uch as styrene, to provide a polymeric backbone. After formation of the backbone, at least 20 one grafting monomer, and preferably two, are pol~er-ized in the presence of the prepolymerized backbone to obtain the graft polymer. These resins are prepared by methods well known in the art. -The backbone polymer, as mentioned, is preferably 25 a conju~ated diene polymer such as polybutadiene, -polyisoprene, or a copolymer, such as butadiene-styrene, butadiene-acrylonitrile, ox the like.
~ he specific conjugated diene monomers normally utilized in preparing the backbone of the graft 30 polymer are generically descrihed by the follo~ing formula:
.
. .
'~.
~2~5~390 X X ~;
\C=C--C=C~
X/ X
wherein X is selected from the group consisting of hydrogen, alkyl groups containing from one to five carbon atoms, chlorine or bromine. Examples of dienes that may be used are butadiene, isoprene, 1,3-hepta-diene, methyl-1,3-pentadiene, 2,3-dimethyl-1,3-buta-diene, 2-ethyl-1,3-pentadiene; 1,3- and 2,4-hexa-dienes, chloro and bromo substituted butadienes such as dichlorobutadiene, bromobutadiene, dibromobuta-diene, mi~tures thereof, and the like. A preferredconjugated diene~is butadiene.
One monomer or group of monomers that may be polymerized in the presence of the prepolymerized backbone are monovinylaromatic hydrocarbons. The monovinylaromatic monomers utilized are generically described by the following formula:
X X X
X~ I=C\
v,~, X X
., X
wherein .~ is as previously defined. Examples of the monovinylaromatic compounds and alkyl-, cycloalkyl-, aryl-, alkaryl-, aralkyl-, alkoxy-, aryloxy-, and other substituted vinylaromatic compounds include styrene, 3-methylstyrene; 3,5-diethylstyrene, 4-n-propylstyrene, ~-methylstyrene, ~-methyl vinyltoluene, ~-chlorostyrene, ~-bromostyrene, dichlorostyrene, dibromostyrene, tetera-chlorostyrene, mixtures thereof, and the like. ~he preferred monovinylaro-matic hydrocarbons used are styrene and/or ~-methylstyreneO
A second sroup of monomers that may be polymer-iæed in the presence of the prepolymeri~ed backbone ;.
~2~S390 are acrylic monomers such as acrylonitrile, substi-tuted acrylonitrile and/or acrylic acid esters/ exem-plified bv acrylonitrile, and alkyl acrylates such as methyl methacrylate.
The acrylonitrile, substituted acrylonitrile, or acrylic acid esters are described generically by the following formula:
X\ X
, /C=C Y
X
wherein Y~ is as previously defined and Y is selected from the group consisting of cyano and carbalkoxy wherein the alkoxy group of the carbalkoxy contains from one to about twelve carbon atoms. Examples of such monomers include acrylonitrile, ethacrylonitrile, methacrylonitrile, ~-chloroacrylonitrile, ~-chloro-acrylonitrile, ~-bromoacrylonitrile, and ~-bromo-acrylonitrile, methyl acrylate, methyl methacrylate, ethyl acrvlate, butyl acrylate, propyl acrylate, isopropyl acrylate, and mixtures thereof. The preferred acrylic monomer is acrylonitrile and the preferred acrylic acid esters are ethyl acrylate and methyl methacrylate.
In the preparation of the graft polymer, the conjugated diolefin polymer or copolymèr exempli~ied by a 1,3-butadiene polymer or copolymer comprises about 50% by weight of the total graft polymer compo-sition. The monomers polymerized in the presence of the backbone, exemplified by styrene and acrylo-nitrile, comprise from about 40 to about 95~ by weight of the total graft polym~er composition.
The second ~roup of grafting monomers, exempli-fied by acrylonitrile, ethyl acrylate or methyl meth-acrylate, of the graft polymer composition, preferably comprise from about 10% to about 40~ by weight of the total graft copolymer composition. The mono~inylaro-matlc hydrocarbon exemplified by styrene comprise from .
.
~53~
about 30 ~o about 70% by ~eight of the total graft polymer composition.
In preparing the polymer, it is normal to have a certain percentage of the polymerizing monomers that are grafted on the backhor.e co~bine with each other and occur as free copolymer. If styrene is utilized as one of the grafting monomers and acrylonitrile as the second grafting monomer, a certain portion of the composition will copolymerize as free styrene-acrylo-nitrile copolymer. In the case where ~methylstyrene(or other monomer) is substituted ~or the styrene in the composition used in preparing the graft polymer, a certain percentage of the composition may be an ~-methylstyrene-acrylonitrile copolymer. Also, there are occasions where a copol~ner, such as ~-methyl-styrene-acrylonitrile, is added to the graft polymer copolymer blend. When the graft as polymer-copolymer blend is referred tc herein, it is meant optionally to include at least one copolvmer blended with the graft polymer composition and which may contain up to 90% of free copolymer.
Optionally, the elastomeric backbone may be an acrylate rubber, such as one based on n-butyl acryl-ate, ethylacrylate, 2-ethylhexylacrylate, and the li~ie. Additionally, minor amounts of a diene may be copolymerized in the acrylate rubber backbone to yield impro~ed grafting Wit]l the matrix polymer.
These resins are well known in the art and many are commercially available.
It is also pos ible to use blends of the forego-ing thermoplastic polymers in 'he present invention.
These blends often result in composition having en-hanced ~MI/RFI shielding effectiveness as compared to the single thermoplastic polymer. Exemplary of useful blends are poly(ethylene terephthalate~/poly(1,4-butylene terephthalate), polycarbonate/poly(ethylene -- lZ~5390 terephthalate) and polycarbonate/poly(~,4-butylene terephthalate).
The ~MI/RFI shielding compositions of the present invention may further comprise thermoplastic addition polymers, rubbers or rubber modified resins.
Preferred addition polymers include those selected from the group consisting of styrene resins, alkyl acrylate resins, or combinations thereof. h~hen used herein and in the appended claims, the terms "styrene resins" and alkyl "acrylate resins" are meant to be defined as set forth below.
Suitable styrene resins include homopolymers~
copolymers and graft copolymers thereof. Especially preferred styrene resins include homopolymer poly-styrene, ABS type graft copolymers, and core-shell type graft copolymers as discIosed in U.S. Patent numbers 4,180,494, 3,808,180; 4,096,20 ; 4,260,693, 4,034,013 and 4,292,233. Also preferred are rubber modified poly~tyrene such as a butadiene rubber modi-fied polystyrene also referred to as high l~act poly-styrene or HIPS; styrene-butadiene-styrene block co-~ ~ ~r ~
polymer such as the Kraton or Kraton-G polymers that are described in U.S. Patent numbers 3,646,162 and 3,595,942; the modified alpha and para substituted styrenes or any of the styrene resins disclosed in United States Patent number 3,383,435.
.
Alkyl acrylate resins which may be used herein include homopolymers and copolymers of alkyl acrylates and alkyl methacrylates in which the alkyl group contains from 1 to 8 carbon atoms, such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacryl-ate. Suitable copolymers include the copolymers of the foregoing ~lith vinyl or allyl monomers (e.g. acrylo-nitrile, N-allymaleimide or N-vinyl maleimide~ or with olefins (e.g. ethylene). Especially preferred alkyl ... . .
~'~45390 acrylate resins are the homopolymers and copolymers of methyl methacrylate ~e.g. polymethyl methacrylate)~
~ dditional acrylic resins useful in the present invention include the core-shell type graft S copolymers, wherein the alkyl acrylate resin, alone or copolymerized wlth a vinvl monomer, may be gxafted onto an elastomeric polyolefin backbone, such as polybutadiene, polybutadiene-styrene, polyisoprene, znd/or butadiene or isoprene copolymers or a rubbery crosslinked acrylate or alkyl acrylate backbone such as n-butylacrylate. These resins are well known in the art (~I.S. 4~o3atol3; U.S. 4,096,202, U.S.
3,808,180, among others) and are commercially available (for e~ample, Rohm & Haas Acryloid XM 653, ~l1 330 and K~ 611).
Also suitable for the present invention are rubbers including ethylene-propylene-diene monomer type rubbers and ethylene-propylene rubbers. Many of these are described in IJ.S. Patent numbers 2,933,480;
3,000,866; 3,407,158; 3,093,621 and 3,379,701.
Especially preferred compositions incorporating therein one or more of the aforementioned addition polymers and the like include polycarbonate/ABS compo-sitions, polyphenylene ether/high impact polystyrene compositions, and poly(butylene terephthalate)/-ethylene ethylacrylate~EEA)-acrylic core-shell gra~t copolymers (Rohm & Haas KM-330).
Optionally, the compositions of this invention may further contain one or more reinforcing agents.
Typical reinorcing agents useful for the invention include but are not limited to, glass fiber, mica or both. The filAmentous glass that may be used in the embodiments of this invention is well known to those skilled in the art and is widely available from a number of manufacturers. The glass may be untreated or, preferably, treated with suitable coupling agents, especially preferred are the silane and titanate ,;
~245390 coupling agents. The glass filaments are made by standard processes, e.g., by steam or air blowing, flame blo~ing and mechanical pulling.
The thermoplastic compositions of the present invention may also be rendered flame retardant with an effective amount of a conventional flame retardant agent. As is well known, flame retardants can be based on elementary red phosphorus, phosphorus com-pounds, halogen and nitrogen compounds alone or pre-ferably in further combination with synergists such asantimony compounds. Especially useful are polymeric and oligomeric flame retardant agents comprising tetrabromohisphenol-A carbonate units, e.g., U.S.
~atent number 3,833,685, alone or in combination with an antimony compound.
The compositions of the present invention may be prepared by known methods. For example, the ingre-dients may be placed into an extrusion compounder with the thermoplastic resin to produce molding pellets wherein the additive ingredients are dispersed in a matrix of the thermoplastic resin. Alternatively, the ingredients may be mixed with a thermoplastic resin by dry blending, then either fluxed on a mill and comminuted, or eXtruded and chopped. Further, the ingredients may also be mixed with powder or granuIar thermoplastic resin and directly molded, e.g., by injection or transferred molding techniques.
Finally, the conductive thermoplastic composi-tions of the present invention may be prepared by first forming a concentrate of any one or more con-ductive fillers in the base thermoplastic resin or any compatible thermoplastic resin (i.e. one which will not cause delamination in the blended composition) and thereafter incorporate the concentrate into the compo-sition hy any of the foregoing methods or methodsknown in the art.
' ' , The novel compositions or composites of the present invention may be molded, ~oamed or e:struded into various structures or articles, especially into electronic equipment, components or housings, requir-ing EMT/RF shielding, and such structures or articlesare included within the scope of the present inven-tion. Examples include, but are not limited to~ panel boards for printed circuits, radio and television panels and housings, and housings for computers and large calculators, audio and high fidelity equipment, ~ensitive test instruments and the like.
In order that those s~illed in the art may better understand how to practice the present invention, the followin~ e~amples are given by way of illustration and not by way of limitation.
E~lI Shielding effectiveness data was determined based on a coaxial transmission method developed by Battelle Laboratorv of Columbus, Ohio. Shielding effectiveness is a measure of the attenuation of EMItRFI expressed in decibels wherein attenuation is a functi~n of the electrical conductivity andjor magnetic susceptability of the shield. ~he decibel unit is a logarithmic measure of the degree of the shielding. A 10 decibel reading indicates that q0% of the EMI/RFI energy is effectively dissipated. Twenty decibels means that 99g of the EMI/RFI is dissipated, and so on. The shielding effectiveness is measured at various radio frequencies (in MHz). In each o~ the following examples, shielding effectiveness was determined over a frequency range of 0.5MHz to 1000MHz, however, only the results for shielding effectiveness at 0.5MHz and 1000MHz are shown.
Unless other~ise specified, all compositions were prepared by extrusion compounding.
FXAMPLES El-E2, Comparative EXAMPLES CEl-CE3 Conductive glass filled and unfilled poly~l,4-butylene terephthalate) compositions were prepared ' ~:
Z~5390 incorporating therein conductive fillers of the prior art as well as the synergistic combination of conduc-tive fillers taught by the present inventio~ All conductive fillers were incorporated by ~te~iknr molding. The compositions and their shielding effec-tiveness are shown in Table 1. The improved shielding effectiveness of the present invention demonstrated by eY.amples E1 + E2 clearly is shown over the prior art formulation of comparative examples CE1 - CE3 (Table 1).
CEl CE2 El E2 CE3 - Poly(1,4-butylene60 55 60 55 55 terephthalate)a Glass Fiber - 10 5 - 5 5 Aluminum Flake - 40 36 ~6 36 Aluminum.Fiber 30 - -4 4-Carbon Fiber - - - - 4 Shielding effec-13-20 25-23 45-31 51-4514-38 tiveness (dB) @ 0.5-lOOOMHz includes 0.2% by wt. stabilizer F..XAMPLES E3-E6, Comparative EXA~IPLES CE3-CE4 A series of glass filied poly(l,4-butylene : ~erephthalate) composition were prepared with various metal and metal coated fiber in combination with the aluminum flake. The specific compositions and their .Shielding effectiveness are shown in Table 2.
.
24539~) ~c ~;r In n Ln u~ ~ I I ~ I I
~ In ~ ~r er ,~ I
C
¢l Ln ~ ~
r~ , - o ~D
o I I I I O
~ r~
E~
u~ o I I I I, Q
r~l ~ er n ~ ..
o a~
D~ N
S-l r~
tl~ O ~rl a~
a) 3 R ~ N U~
Ql Q
rl O Q
~ O rl oP
o rt~ 1 c) o 4~
a) R a~
~ ~ h ~ ~ o v td R ~ u~ U O V~ ~J a~ o .
I Q ~ u2 ~ U
a~
o ~ ~ ~ c o ~ ~ ",, ~
Z ~ * td ,:
~LZ~53~0 ~ x2mples F,3 - ~6 demonstrate the usefulness of various me.al and metal coated fibers for the present invention. A comparison of CE2 and CE4 with E3 clearly demonstrates the enhancement in shielding 5 effectiveness by the use of the synergistic combin-ation of conductive fillers.
EX~PLrS E7-E12, Comparative EXAMPLE CE5 Co~positions were prepared by extrusion compound-ing o. all conductive fillers and then injection mold-lO ing. Various levels of aluminum flake and nickel coated carbon fiber were used demonstrating the need for at least about 25~ aluminum flake. The formula-tions and shielding effectiveness are shown in Table 3.
\
.
`: :
'.
-- ~
~53~C~
. . r~
r~
U~ ~ CO
r~
. .
o In ~ .
~D r) ~D
O I
. .
l-) G U~
l~ ~ CO
, Ct.' I~-- ~ C ~
' ~`: ' .
G~ ~ ~
E~
~r)OG ~
~ U~ ~ ~ O
C~ .. .~
C` rl .,, . Q
~J
U~
.~, .
~ ~ .
Q
~) ~,1 0 N
~ O
O ~ OC
~1 o Q ~ o Q a) 4~ , I R ~ ti~ G ~
~ 1 0 ~ ^
O ~ ~ r1 ,C ~
,, ~ ~ ~ Z U~
". ~
"
Comparison of CE5 with EY.amples E7-E12 demon-strate the need for at least about 25~ aluminum flake.
Shieldir.g effectiveness as a whole suffers somewhat when all insredients are mixed by extrusion. This is most likely due to breakage of fibers.
EXA~5PLES E13-E15 Polymer blends with poly(l,4-butylene terephthal~
ate) were prepared to demonstrate the present inven-tions usefulness in such compositions. The formula-tion and Shielding effectiveness are presented inTahle 4. A comparison of the resul's shows enhance-ment of shielding effectiveness in the blend over the strict poly(l,4-butylene terephthalate).
E13 E14 ~15 Poly(1,4-butylene terephthalate)a 61.3 46.3 46.3 Aluminum flake 31 31 31 Aluminum fiber 3.4 3.4 3.4 Glass fiber 4.3 4.3 4.3 Poly(ethylene terephthzlate) - 15 Polycarbonate - 15 Shielding effectiveness 40-29 44-30 48-34 (dB) @ 0.5-lOOOMHz a includes 0.2% by wt. stabilizer EXAMPLES E16 and E17 Flame retardant and impact modified poly(1,4-butylene terephthalate) may also be rendered conduc-tive by the present invention. The formulation znd results zre shown in Table 5.
, ~
''-~Z 4S390 - 2& - 8CV-4015 , i Poly(1,4-butylene terephthalate)a 46.3 46.3 5 Aluminum flake 31 31 Aluminum fiber 3.4 3.4 Glass fiber 4.3 4.3 Flame retardantb 15 Impact ~.odifierC - 15 Shielding effectiveness 35-29 30-~1 (dB) @ 0.5-lOOOMHz a. includes 0.2% by wt. stabilizer b. halogenated bisphenol based polycarbonate flame retardant in combination with antimony oxide.
c. KM330 core-shell acrylic-styrenic impact modifier (Rohm & Haas) and ethylene ethylacrylate blend.
EX~PLES E18-E22 A series of compositions comprising different base polymers with the synergistic combination of conductive fillers were prepared to demonstrate the usefulness of the present teaching to other linear thermoplastic polymers and blends thereof. The specific formulations and results are presented in Table 6.
S39~
'`31 ~ ~r I I I I o i'l ~r ~D ~r o I I ~
er o ~ i`
ol ~D ~ I I o ~r a~ I O I I 'I
~ O
~ . ~ .
-~1l ~ 0 S~
S ~ ~ ~
~1 ~ ~ rl 3 o o ~ r~ ~
EiEi R S ` s: ~ tn o : I I S-l JJ ~ Il) 1~] r~
Ei k ~ ~ o ~ .E~ ~ ~
r ~ I rl ~
~ ~ O O ~1 ~ O S -' .
~ 5390 Obviously, other modifications and variations of the present invention are possible in light of the above teachingsO For example, these compositions may further comprise plasticizers, antioxidants, stabil-izers, flow promoters, mold release agents, UV stabil-izers, and the like, as necessary. It is therefore to be understcod that changes may be made in the partic-ular embodiments of the invention described which are within the ~ull intended scope of the invention so`
defined by the appended claims.
~2~53~30 (e) ~OLYAMIDE-I~5IDES
The polyamide-imide copolymers useful for the present invention generally ha~re a crystalline struc-ture and a melting point of over about 340C. They 5 are prepared by the reaction of dianhydrides with - diamines containing preformed amide groups resulting in an amide-imide structure as follows:
O O
\ ~ C C - NH N \ ~ N-~ ~ ~C~ .
Other copolymers can be prepared by the reaction of trimelletic anhydride acid chloride with aromatic diamines. These copolymers can be prepared by ths methods disclosed in Supplement Volume, Kirk - Othmer Encyclopedia of Chemical Technology, pages 746 ~ 773 (1971).
~f) POLYPHENYLE~E ETHER
The polyphenylene ether resins useful for the present invention comprise ho~opolymers and copolymers of structural units of the formula:
1~~
Q " Q' n wherein Q, Q', Q'' and Q' " are independently selected from the group consisting of hyflrogen, hydrocarbon radicals, halohydrocarbon radicals having at least 2 carbon atoms between the halogen atom and the phenyl nucleus, hydrocaxbonoxy radicals and halohydrocar-bonoxy radicals having at least 2 carbon atoms betweenthe halogen atom and phenyl nucleus, and Q', Q'' and Q''' in addition may be halogen with the provi~o that Q and Q' are both free of a tertiary carbon atom; and lZ45390 n represents the total number of monomer residues and is an interger of at least 50.
The preferred polyphenylene ether resin is a poly~2,6-dimethyl-1,4-phenylene)ether resin having an intrinsic viscosity of from about 0.3 dlJg to about 0.60 dl/g in chloroform. The polyphenylene ether resins useful herein are well known in the art and may be prepared from a number of catalytic and non-cata lytic processes from correspondiny phenols or reactive derivates thereof. Examples of polyphenylene ethers and methods for their production are disclosed in U.S.
Patent numbers 3,306,874; 3,306,875; 3,257,357 and 3,257,358.
(c? POLYETHERIMIDES
Polyetherimides useful for the present invention may be prepared from the reaction between sub-stantially equimolar amounts o' aromatic bis(ether anhydride)s of the formula, O - O
I O /\ ~ O-P~-O - ~ /O
ll ll O O
and organic diamine of the formula, I T
the reaction may take place in the prsence or absence of a solvent and/or catalytic agent or compound, as known in the art.
~s shown in formula I, R is a member selected from the class consisting of (a) the following divalent organic radicals:
' --- lZ4S39~
CH3 Cl'13 3 CH3 c~3 c~3 CH ~ Br Br ~ CH3 and 3 Br Br 3 Br Br C(CH3) Br Br and (b) divalent organic radicals of the general formula ( )m ~
where X is a member selected from the class consisting of divalent radicals of the formula O O
CyR2~ C-, -S-, -O-, -C(CH ) o and - S-, m is 0 or l, and y is a whole number from 1 to 5. R' as shown in formula II is a divalent organic rad.ical selected from the class consisting of (a) aromatic hydrocarbon radicals having from 6 - 20 carbon atoms and halogenated derivates thereof, ~b) 15 alkylene radicals, C(2 8) alkylene terminated polvdiorganosiloxan~, cvcloalkylene radicals having from 2 - 20 carbon atoms and (c) di~alent radicals included by the formula, ' ~2453~0 ~ (Q)m ~
where Q is a member selected from the class consisting ~f O O
~l , CXH2x- and -C(C~ ) and x is a whole number from 1 to 5 inclusive, and m is as previously defined. These polyetherimides are prepared by methods well known in the art such as those described in, for example~ U.S. Patent numbers 3,917,643; 3,~52,242; 3,855,176; 3,~33,546; 3,875,116;
3,83~,097; 3,905,942 and 3,933,719.
-,,~; .
(h) ACR'LONITRILE BUTADIENE STYRENE COPOLYMERS
In general, ABS type polymers contain two or more polymeric parts of different compositions which are 15 bonded chemically. The polymer is preferably prepared by polymerizing a conjugated diene, such as butadiene or a conjugated diene with a monomer copolymerizable therewith, ~uch as styrene, to provide a polymeric backbone. After formation of the backbone, at least 20 one grafting monomer, and preferably two, are pol~er-ized in the presence of the prepolymerized backbone to obtain the graft polymer. These resins are prepared by methods well known in the art. -The backbone polymer, as mentioned, is preferably 25 a conju~ated diene polymer such as polybutadiene, -polyisoprene, or a copolymer, such as butadiene-styrene, butadiene-acrylonitrile, ox the like.
~ he specific conjugated diene monomers normally utilized in preparing the backbone of the graft 30 polymer are generically descrihed by the follo~ing formula:
.
. .
'~.
~2~5~390 X X ~;
\C=C--C=C~
X/ X
wherein X is selected from the group consisting of hydrogen, alkyl groups containing from one to five carbon atoms, chlorine or bromine. Examples of dienes that may be used are butadiene, isoprene, 1,3-hepta-diene, methyl-1,3-pentadiene, 2,3-dimethyl-1,3-buta-diene, 2-ethyl-1,3-pentadiene; 1,3- and 2,4-hexa-dienes, chloro and bromo substituted butadienes such as dichlorobutadiene, bromobutadiene, dibromobuta-diene, mi~tures thereof, and the like. A preferredconjugated diene~is butadiene.
One monomer or group of monomers that may be polymerized in the presence of the prepolymerized backbone are monovinylaromatic hydrocarbons. The monovinylaromatic monomers utilized are generically described by the following formula:
X X X
X~ I=C\
v,~, X X
., X
wherein .~ is as previously defined. Examples of the monovinylaromatic compounds and alkyl-, cycloalkyl-, aryl-, alkaryl-, aralkyl-, alkoxy-, aryloxy-, and other substituted vinylaromatic compounds include styrene, 3-methylstyrene; 3,5-diethylstyrene, 4-n-propylstyrene, ~-methylstyrene, ~-methyl vinyltoluene, ~-chlorostyrene, ~-bromostyrene, dichlorostyrene, dibromostyrene, tetera-chlorostyrene, mixtures thereof, and the like. ~he preferred monovinylaro-matic hydrocarbons used are styrene and/or ~-methylstyreneO
A second sroup of monomers that may be polymer-iæed in the presence of the prepolymeri~ed backbone ;.
~2~S390 are acrylic monomers such as acrylonitrile, substi-tuted acrylonitrile and/or acrylic acid esters/ exem-plified bv acrylonitrile, and alkyl acrylates such as methyl methacrylate.
The acrylonitrile, substituted acrylonitrile, or acrylic acid esters are described generically by the following formula:
X\ X
, /C=C Y
X
wherein Y~ is as previously defined and Y is selected from the group consisting of cyano and carbalkoxy wherein the alkoxy group of the carbalkoxy contains from one to about twelve carbon atoms. Examples of such monomers include acrylonitrile, ethacrylonitrile, methacrylonitrile, ~-chloroacrylonitrile, ~-chloro-acrylonitrile, ~-bromoacrylonitrile, and ~-bromo-acrylonitrile, methyl acrylate, methyl methacrylate, ethyl acrvlate, butyl acrylate, propyl acrylate, isopropyl acrylate, and mixtures thereof. The preferred acrylic monomer is acrylonitrile and the preferred acrylic acid esters are ethyl acrylate and methyl methacrylate.
In the preparation of the graft polymer, the conjugated diolefin polymer or copolymèr exempli~ied by a 1,3-butadiene polymer or copolymer comprises about 50% by weight of the total graft polymer compo-sition. The monomers polymerized in the presence of the backbone, exemplified by styrene and acrylo-nitrile, comprise from about 40 to about 95~ by weight of the total graft polym~er composition.
The second ~roup of grafting monomers, exempli-fied by acrylonitrile, ethyl acrylate or methyl meth-acrylate, of the graft polymer composition, preferably comprise from about 10% to about 40~ by weight of the total graft copolymer composition. The mono~inylaro-matlc hydrocarbon exemplified by styrene comprise from .
.
~53~
about 30 ~o about 70% by ~eight of the total graft polymer composition.
In preparing the polymer, it is normal to have a certain percentage of the polymerizing monomers that are grafted on the backhor.e co~bine with each other and occur as free copolymer. If styrene is utilized as one of the grafting monomers and acrylonitrile as the second grafting monomer, a certain portion of the composition will copolymerize as free styrene-acrylo-nitrile copolymer. In the case where ~methylstyrene(or other monomer) is substituted ~or the styrene in the composition used in preparing the graft polymer, a certain percentage of the composition may be an ~-methylstyrene-acrylonitrile copolymer. Also, there are occasions where a copol~ner, such as ~-methyl-styrene-acrylonitrile, is added to the graft polymer copolymer blend. When the graft as polymer-copolymer blend is referred tc herein, it is meant optionally to include at least one copolvmer blended with the graft polymer composition and which may contain up to 90% of free copolymer.
Optionally, the elastomeric backbone may be an acrylate rubber, such as one based on n-butyl acryl-ate, ethylacrylate, 2-ethylhexylacrylate, and the li~ie. Additionally, minor amounts of a diene may be copolymerized in the acrylate rubber backbone to yield impro~ed grafting Wit]l the matrix polymer.
These resins are well known in the art and many are commercially available.
It is also pos ible to use blends of the forego-ing thermoplastic polymers in 'he present invention.
These blends often result in composition having en-hanced ~MI/RFI shielding effectiveness as compared to the single thermoplastic polymer. Exemplary of useful blends are poly(ethylene terephthalate~/poly(1,4-butylene terephthalate), polycarbonate/poly(ethylene -- lZ~5390 terephthalate) and polycarbonate/poly(~,4-butylene terephthalate).
The ~MI/RFI shielding compositions of the present invention may further comprise thermoplastic addition polymers, rubbers or rubber modified resins.
Preferred addition polymers include those selected from the group consisting of styrene resins, alkyl acrylate resins, or combinations thereof. h~hen used herein and in the appended claims, the terms "styrene resins" and alkyl "acrylate resins" are meant to be defined as set forth below.
Suitable styrene resins include homopolymers~
copolymers and graft copolymers thereof. Especially preferred styrene resins include homopolymer poly-styrene, ABS type graft copolymers, and core-shell type graft copolymers as discIosed in U.S. Patent numbers 4,180,494, 3,808,180; 4,096,20 ; 4,260,693, 4,034,013 and 4,292,233. Also preferred are rubber modified poly~tyrene such as a butadiene rubber modi-fied polystyrene also referred to as high l~act poly-styrene or HIPS; styrene-butadiene-styrene block co-~ ~ ~r ~
polymer such as the Kraton or Kraton-G polymers that are described in U.S. Patent numbers 3,646,162 and 3,595,942; the modified alpha and para substituted styrenes or any of the styrene resins disclosed in United States Patent number 3,383,435.
.
Alkyl acrylate resins which may be used herein include homopolymers and copolymers of alkyl acrylates and alkyl methacrylates in which the alkyl group contains from 1 to 8 carbon atoms, such as methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacryl-ate. Suitable copolymers include the copolymers of the foregoing ~lith vinyl or allyl monomers (e.g. acrylo-nitrile, N-allymaleimide or N-vinyl maleimide~ or with olefins (e.g. ethylene). Especially preferred alkyl ... . .
~'~45390 acrylate resins are the homopolymers and copolymers of methyl methacrylate ~e.g. polymethyl methacrylate)~
~ dditional acrylic resins useful in the present invention include the core-shell type graft S copolymers, wherein the alkyl acrylate resin, alone or copolymerized wlth a vinvl monomer, may be gxafted onto an elastomeric polyolefin backbone, such as polybutadiene, polybutadiene-styrene, polyisoprene, znd/or butadiene or isoprene copolymers or a rubbery crosslinked acrylate or alkyl acrylate backbone such as n-butylacrylate. These resins are well known in the art (~I.S. 4~o3atol3; U.S. 4,096,202, U.S.
3,808,180, among others) and are commercially available (for e~ample, Rohm & Haas Acryloid XM 653, ~l1 330 and K~ 611).
Also suitable for the present invention are rubbers including ethylene-propylene-diene monomer type rubbers and ethylene-propylene rubbers. Many of these are described in IJ.S. Patent numbers 2,933,480;
3,000,866; 3,407,158; 3,093,621 and 3,379,701.
Especially preferred compositions incorporating therein one or more of the aforementioned addition polymers and the like include polycarbonate/ABS compo-sitions, polyphenylene ether/high impact polystyrene compositions, and poly(butylene terephthalate)/-ethylene ethylacrylate~EEA)-acrylic core-shell gra~t copolymers (Rohm & Haas KM-330).
Optionally, the compositions of this invention may further contain one or more reinforcing agents.
Typical reinorcing agents useful for the invention include but are not limited to, glass fiber, mica or both. The filAmentous glass that may be used in the embodiments of this invention is well known to those skilled in the art and is widely available from a number of manufacturers. The glass may be untreated or, preferably, treated with suitable coupling agents, especially preferred are the silane and titanate ,;
~245390 coupling agents. The glass filaments are made by standard processes, e.g., by steam or air blowing, flame blo~ing and mechanical pulling.
The thermoplastic compositions of the present invention may also be rendered flame retardant with an effective amount of a conventional flame retardant agent. As is well known, flame retardants can be based on elementary red phosphorus, phosphorus com-pounds, halogen and nitrogen compounds alone or pre-ferably in further combination with synergists such asantimony compounds. Especially useful are polymeric and oligomeric flame retardant agents comprising tetrabromohisphenol-A carbonate units, e.g., U.S.
~atent number 3,833,685, alone or in combination with an antimony compound.
The compositions of the present invention may be prepared by known methods. For example, the ingre-dients may be placed into an extrusion compounder with the thermoplastic resin to produce molding pellets wherein the additive ingredients are dispersed in a matrix of the thermoplastic resin. Alternatively, the ingredients may be mixed with a thermoplastic resin by dry blending, then either fluxed on a mill and comminuted, or eXtruded and chopped. Further, the ingredients may also be mixed with powder or granuIar thermoplastic resin and directly molded, e.g., by injection or transferred molding techniques.
Finally, the conductive thermoplastic composi-tions of the present invention may be prepared by first forming a concentrate of any one or more con-ductive fillers in the base thermoplastic resin or any compatible thermoplastic resin (i.e. one which will not cause delamination in the blended composition) and thereafter incorporate the concentrate into the compo-sition hy any of the foregoing methods or methodsknown in the art.
' ' , The novel compositions or composites of the present invention may be molded, ~oamed or e:struded into various structures or articles, especially into electronic equipment, components or housings, requir-ing EMT/RF shielding, and such structures or articlesare included within the scope of the present inven-tion. Examples include, but are not limited to~ panel boards for printed circuits, radio and television panels and housings, and housings for computers and large calculators, audio and high fidelity equipment, ~ensitive test instruments and the like.
In order that those s~illed in the art may better understand how to practice the present invention, the followin~ e~amples are given by way of illustration and not by way of limitation.
E~lI Shielding effectiveness data was determined based on a coaxial transmission method developed by Battelle Laboratorv of Columbus, Ohio. Shielding effectiveness is a measure of the attenuation of EMItRFI expressed in decibels wherein attenuation is a functi~n of the electrical conductivity andjor magnetic susceptability of the shield. ~he decibel unit is a logarithmic measure of the degree of the shielding. A 10 decibel reading indicates that q0% of the EMI/RFI energy is effectively dissipated. Twenty decibels means that 99g of the EMI/RFI is dissipated, and so on. The shielding effectiveness is measured at various radio frequencies (in MHz). In each o~ the following examples, shielding effectiveness was determined over a frequency range of 0.5MHz to 1000MHz, however, only the results for shielding effectiveness at 0.5MHz and 1000MHz are shown.
Unless other~ise specified, all compositions were prepared by extrusion compounding.
FXAMPLES El-E2, Comparative EXAMPLES CEl-CE3 Conductive glass filled and unfilled poly~l,4-butylene terephthalate) compositions were prepared ' ~:
Z~5390 incorporating therein conductive fillers of the prior art as well as the synergistic combination of conduc-tive fillers taught by the present inventio~ All conductive fillers were incorporated by ~te~iknr molding. The compositions and their shielding effec-tiveness are shown in Table 1. The improved shielding effectiveness of the present invention demonstrated by eY.amples E1 + E2 clearly is shown over the prior art formulation of comparative examples CE1 - CE3 (Table 1).
CEl CE2 El E2 CE3 - Poly(1,4-butylene60 55 60 55 55 terephthalate)a Glass Fiber - 10 5 - 5 5 Aluminum Flake - 40 36 ~6 36 Aluminum.Fiber 30 - -4 4-Carbon Fiber - - - - 4 Shielding effec-13-20 25-23 45-31 51-4514-38 tiveness (dB) @ 0.5-lOOOMHz includes 0.2% by wt. stabilizer F..XAMPLES E3-E6, Comparative EXA~IPLES CE3-CE4 A series of glass filied poly(l,4-butylene : ~erephthalate) composition were prepared with various metal and metal coated fiber in combination with the aluminum flake. The specific compositions and their .Shielding effectiveness are shown in Table 2.
.
24539~) ~c ~;r In n Ln u~ ~ I I ~ I I
~ In ~ ~r er ,~ I
C
¢l Ln ~ ~
r~ , - o ~D
o I I I I O
~ r~
E~
u~ o I I I I, Q
r~l ~ er n ~ ..
o a~
D~ N
S-l r~
tl~ O ~rl a~
a) 3 R ~ N U~
Ql Q
rl O Q
~ O rl oP
o rt~ 1 c) o 4~
a) R a~
~ ~ h ~ ~ o v td R ~ u~ U O V~ ~J a~ o .
I Q ~ u2 ~ U
a~
o ~ ~ ~ c o ~ ~ ",, ~
Z ~ * td ,:
~LZ~53~0 ~ x2mples F,3 - ~6 demonstrate the usefulness of various me.al and metal coated fibers for the present invention. A comparison of CE2 and CE4 with E3 clearly demonstrates the enhancement in shielding 5 effectiveness by the use of the synergistic combin-ation of conductive fillers.
EX~PLrS E7-E12, Comparative EXAMPLE CE5 Co~positions were prepared by extrusion compound-ing o. all conductive fillers and then injection mold-lO ing. Various levels of aluminum flake and nickel coated carbon fiber were used demonstrating the need for at least about 25~ aluminum flake. The formula-tions and shielding effectiveness are shown in Table 3.
\
.
`: :
'.
-- ~
~53~C~
. . r~
r~
U~ ~ CO
r~
. .
o In ~ .
~D r) ~D
O I
. .
l-) G U~
l~ ~ CO
, Ct.' I~-- ~ C ~
' ~`: ' .
G~ ~ ~
E~
~r)OG ~
~ U~ ~ ~ O
C~ .. .~
C` rl .,, . Q
~J
U~
.~, .
~ ~ .
Q
~) ~,1 0 N
~ O
O ~ OC
~1 o Q ~ o Q a) 4~ , I R ~ ti~ G ~
~ 1 0 ~ ^
O ~ ~ r1 ,C ~
,, ~ ~ ~ Z U~
". ~
"
Comparison of CE5 with EY.amples E7-E12 demon-strate the need for at least about 25~ aluminum flake.
Shieldir.g effectiveness as a whole suffers somewhat when all insredients are mixed by extrusion. This is most likely due to breakage of fibers.
EXA~5PLES E13-E15 Polymer blends with poly(l,4-butylene terephthal~
ate) were prepared to demonstrate the present inven-tions usefulness in such compositions. The formula-tion and Shielding effectiveness are presented inTahle 4. A comparison of the resul's shows enhance-ment of shielding effectiveness in the blend over the strict poly(l,4-butylene terephthalate).
E13 E14 ~15 Poly(1,4-butylene terephthalate)a 61.3 46.3 46.3 Aluminum flake 31 31 31 Aluminum fiber 3.4 3.4 3.4 Glass fiber 4.3 4.3 4.3 Poly(ethylene terephthzlate) - 15 Polycarbonate - 15 Shielding effectiveness 40-29 44-30 48-34 (dB) @ 0.5-lOOOMHz a includes 0.2% by wt. stabilizer EXAMPLES E16 and E17 Flame retardant and impact modified poly(1,4-butylene terephthalate) may also be rendered conduc-tive by the present invention. The formulation znd results zre shown in Table 5.
, ~
''-~Z 4S390 - 2& - 8CV-4015 , i Poly(1,4-butylene terephthalate)a 46.3 46.3 5 Aluminum flake 31 31 Aluminum fiber 3.4 3.4 Glass fiber 4.3 4.3 Flame retardantb 15 Impact ~.odifierC - 15 Shielding effectiveness 35-29 30-~1 (dB) @ 0.5-lOOOMHz a. includes 0.2% by wt. stabilizer b. halogenated bisphenol based polycarbonate flame retardant in combination with antimony oxide.
c. KM330 core-shell acrylic-styrenic impact modifier (Rohm & Haas) and ethylene ethylacrylate blend.
EX~PLES E18-E22 A series of compositions comprising different base polymers with the synergistic combination of conductive fillers were prepared to demonstrate the usefulness of the present teaching to other linear thermoplastic polymers and blends thereof. The specific formulations and results are presented in Table 6.
S39~
'`31 ~ ~r I I I I o i'l ~r ~D ~r o I I ~
er o ~ i`
ol ~D ~ I I o ~r a~ I O I I 'I
~ O
~ . ~ .
-~1l ~ 0 S~
S ~ ~ ~
~1 ~ ~ rl 3 o o ~ r~ ~
EiEi R S ` s: ~ tn o : I I S-l JJ ~ Il) 1~] r~
Ei k ~ ~ o ~ .E~ ~ ~
r ~ I rl ~
~ ~ O O ~1 ~ O S -' .
~ 5390 Obviously, other modifications and variations of the present invention are possible in light of the above teachingsO For example, these compositions may further comprise plasticizers, antioxidants, stabil-izers, flow promoters, mold release agents, UV stabil-izers, and the like, as necessary. It is therefore to be understcod that changes may be made in the partic-ular embodiments of the invention described which are within the ~ull intended scope of the invention so`
defined by the appended claims.
Claims (37)
1. A thermoplastic polymeric composition having high electromagnetic interference shielding effectiveness comprising (a) a thermoplastic resin or resin blend, (b) from about 25 to about 50% by weight based on the total composition of metal flake, and (c) from about 2 to about 12% by weight based on the total composition of metal or metal coated fiber, wherein the weight ratio of flake to fiber is from about 4:1 to about 14:1.
2. The composition of Claim 1 wherein the thermoplastic resin (a) is selected from the group consisting of polyesters, polycarbonates, polyamides, co-polyetheresters, polyphenylene ethers, co-polyester-carbonates, poly(aryl ether)s, polyamide imides, polyetherimides, polystyrenes, acrylonitrile butadiene styrene copolymers and blends thereof.
3. A composition as defined in Claim 2 wherein the polyester has repeating units of the general formula wherein n is a whole number of from 2 to 4.
4. The composition of Claim 3 wherein the polyester is poly(1,4-butylene terephthalate).
5. The composition of Claim 3 wherein the polyester is poly(ethylene terephthalate).
6. A composition of Claim 2 wherein the polycarbonate is an aromatic polycarbonate derived from 2,2-bis(4-hydroxy phenyl)propane.
7. A composition of Claim 2 wherein the polyamide is Nylon 6,6.
8. A composition of Claim 2 wherein the thermoplastic resin (a) is a blend of poly(ethylene terephthalate) and poly(1,4-butylene terephthalate).
9. A composition of Claim 2 wherein the thermoplastic resin (a) is a blend of polycarbonate and poly(1,4-butylene terephthalate).
10. A composition of Claim 2 wherein the thermoplastic resin (a) is a blend of polycarbonate and poly(ethylene terephthalate).
11. The composition of Claim 2 wherein the thermoplastic polymer is polyphenylene ether.
12. The composition of Claim 11 which further comprises a rubber or a rubber modified thermoplastic resin selected from the group consisting of high impact polystyrene, rubber modified alpha-substituted or para-substituted styrene polymers, ethylene-propylene rubber and ethylene propylene-diene monomer rubbers.
13. The composition of Claim 2 wherein the thermo-plastic condensation polymer (a) is a blend of polyphenylene ether and high impact polystyrene.
14. A composition as defined in Claim 2 which further comprises a thermoplastic addition polymer resin.
15. The composition of Claim 14 wherein the thermo-plastic addition polymer resin is selected from the group consisting of 2 styrene resin, an alkyl acrylate resin or a mixture of any of the foregoing.
16. The composition of Claim 15 wherein the thermo-plastic addition polymer resin is acrylonitrile-butadiene-styrene resin.
17. The composition of Claim 6 which further comprises acrylonitrile-butadiene-stryene resin.
18. The composition of Claim 15 wherein the thermo-plastic addition polymer is a graft copolymer selected from the group consisting of core-shell type acrylic elastomers, acrylic copolymers and vinylic copolymers.
19. The composition of Claim 15 wherein the addition polymer is a blend of a graft copolymer and ethylene ethylacrylate.
20. A composition as defined in Claim 2 which further comprises a rubber or a rubber modified resin selected from the group consisting essentially of high impact polystyrene, rubber modified substituted styrene resins, ethylene-propylene-diene monomer rubbers and ethylene-propylene rubbers.
21. The composition as defined in Claim 1 wherein the metal flake is present in an amount of from about 30 to about 40% by weight.
22. The composition as defined in Claim 1 wherein the metal flake is selected from the group consisting essentially of aluminum flake, nickel flake, copper flake and silver flake.
23. The composition of Claim 22 wherein the flake is aluminum or aluminum alloy.
24. The composition of Claim 1 wherein the weight ratio of flake to fiber is from about 6:1 to about 10:1.
25. The composition of Claim 1 wherein the metal or metal coated fibers are present in an amount of from about 4 to about 8% by weight based on the total composition.
26. The composition of Claim 1 wherein the metal fibers are selected from the group consisting essentially of aluminum fibers, stainless steel fibers, nickel fibers, silver fibers, copper fibers, and fibers prepared from alloy thereof.
27. The composition of Claim 1 wherein the metal coated fibers are selected from the group consisting essentially of metal coated glass and carbon fibers.
28. The composition of Claim 27 wherein the metal coating is selected from the group consisting essentially of nickel, aluminum, silver, copper and alloys thereof.
29. The composition of Claim 27 wherein the metal coated fiber is aluminum coated glass fiber.
30. The composition of Claim 27 wherein the metal coated fiber is nickel coated graphite fiber.
31. The composition of Claim 1 which further comprises from about 3 to about 25%
by weight of glass fibers.
by weight of glass fibers.
32. The composition as defined in Claim 2 which further comprises from about 3 to about 25% by weight of glass fibers.
33. The composition as defined in Claim 14 which further comprises from about 3 to about 25% by weight of glass fibers.
34. The composition as defined in Claim 20 which further comprises from about 3 to about 25% by weight of glass fibers.
35. The composition of Claim 1 which further comprises an effective amount of flame retardant.
36. The composition of Claim 31 which further comprises an effective amount of flame retardant.
37. The composition of Claim 35 wherein the flame retardant is selected from the group consisting essentially of halogenated bisphenol based polycarbonate and phosphorus compounds, either alone or in combination with an antimony compound.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL8204288 | 1982-11-05 | ||
| NL8204288A NL8204288A (en) | 1982-11-05 | 1982-11-05 | POLYMER MIX, METHOD FOR PREPARING THE POLYMER MIX, ARTICLES FORMED FROM THE POLYMER MIX. |
| US545,339 | 1983-10-25 | ||
| US06/545,339 US4566990A (en) | 1982-11-05 | 1983-10-25 | Synergistic effect of metal flake and metal or metal coated fiber on EMI shielding effectiveness of thermoplastics |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1245390A true CA1245390A (en) | 1988-11-22 |
Family
ID=26645826
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000440432A Expired CA1245390A (en) | 1982-11-05 | 1983-11-04 | Synergistic effect of metal flake and metal or metal coated fiber on emi shielding effectiveness of thermoplastics |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1245390A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9901017B2 (en) | 2011-05-24 | 2018-02-20 | Sabic Global Technologies B.V. | EMI shielding material having improved delamination behavior |
-
1983
- 1983-11-04 CA CA000440432A patent/CA1245390A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9901017B2 (en) | 2011-05-24 | 2018-02-20 | Sabic Global Technologies B.V. | EMI shielding material having improved delamination behavior |
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