CA1239239A - Polycarbonate blends having low gloss - Google Patents

Abstract

POLYCARBONATE BLENDS HAVING LOW GLOSS
ABSTRACT OF THE DISCLOSURE
The present invention is directed to a thermo-plastic molding composition comprising a blend of an aromatic polycarbonate, a graft copolymer and an impact modifier graft characterized by its properties wherein combined are low gloss and high impact strength.

Description

~3~3~
Mo-2456 PC~ 6 OLYCARBONATE BLENDS HAVING LOW GLOSS
FIELD OF THE INVENTION
The present invention is directed to a thermo-plastic molding composition and, more par~icularly, to a composition comprising a polycarbonate resin and a gra:ft eopolymer.
SUMelARY OF THE INVENTION
The thermoplastic molding compositions of the invention comprising an aromatic polycarbonate resin, a graft copolymer of acrylonitrile-butadiene-styrene and an elastomeric impact modifier are characterized by their properties including the combination of low gloss, high ultimate strength and high impact strength at low temperatures.
_ KGROUND OF THE INVENTION
Compositions containing a blend of polycar-bonate and ABS were disclosed in U S. Patents 3,130,177 and 3,852,393. Similar compositions were disclosed in ~ U.S. Patents 3,954,905 and 3,988,389 to possess ; 20 improved weld line strength.
Improved impact strength of polycarbonates by the incorporation of a graft elastomer has been the subject of numerous U.S. Patents, for instance, 4,299,928, 4,245,058, Re. 28,723, 4,263,4167 4,263,415, 4,260,693 and 4,G82,895 among others.
In some applications, notably power tool housing, business machine enclosures and automotive parts, the design requirements limit the permissible degree of gloss while at the same time specify a high degree of resistance to impact, especially as expressed in a relatively low sensitivity to notch effects.

~o-2456 ~ ' ~

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The present invention discloses thermoplastic compositions eminently suitable for these applications.
Gloss, as a material property, is determined in accordance with ASTM D~528, Standard Method of Test for Specular G]oss.
DETAII,ED DESCRIPTION OF THE INVENTION
.
The Polycarbonate Resin The polycarbonate resins useful in the practice of the invention are homopolycarbonates, co-polycarbonates and terpolycarbonates or mixtures there-of. The polycarbonates generally have molecular weights of 10,000-203,000 (average molecular weight), preferably 20,000-80,0Q0 and may have a melt flow rate per ASTM D-1238 at 300C of about 1 to about 24 gm/10 min., preferably about 2-6 gm/10 min. They may be prepared, for example, by the known diphasic interface process from a carbonic acid derivative such as phos-gene and from dihydroxy compounds by polycondensation see German Offenlegungsschriften 2,063,050; 2,0~3,052;
1,570,703; 2,211,956; 2,211,957 and 2,248,817; French Patent 1,561,518; and the monograph H. Schnell, "Chemis-try and Physics of Polycarbonates", Interscience Publishers, New York, 1964.
In the present context, dihydroxy compounds suitable for the preparation o~ the copolycarbonates of the invention conform to the structural formulae (1) or

(2) Mo-2456 =:

,~'g <~o~ (1) : (Z)d (z)d e H~ OH (2) ( )f (z)f wherein A denotes an alkylene group with 1 to ~ carbon atoms, an alkylidene group with 2 to 8 carbon atoms, a cyclo-5 . alkylene group with 5 to 15 carbon atoms, a cycloalkyli-dene group with 5 to 15 carbon atoms, a carbonyl group, an oxygen atom, a sulfur atom, an -SO- or -S02~
radical; or a radical conforming to ~H3 C H 3 ~C or C ~ CH 3 e and g both denote the number 0 to 1;
Z denotes F, Cl, Br or Cl-C4-alkyl and if several Z
radicals are substituents in one aryl radical, ~hey may be identical or different;
d denotes 0 or an integer of from 1 to 4 and f denotes 0 or an integer of from 1 to 3.
Among the useful bisphenols in the practice of the invention are hydroquinone, resorcinol, bis-(hydroxyphenyl~-alkanes, bis-~hydroxyphenyl)-ethers, bis-(hydroxyphenyl)-ketones, bis-(hydroxyphenyl)-sulfoxides, bis-(hydroxyphenyl)-sulfones and ~, ~-bis-(hydroxyphenyl~-diisopropyl-benzenes, as well as their Mo-2456 :

nuclear-alkylated compounds. These and further suitable aromatic dihydroY~y compounds are described, for example, in U.S. Patents 3,028,365; 2,999,835;

3,1~8,172; 2,991,273; 3,271,367; and 2,999,846.
Further examples of suitable bisphenols are 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol-A), ~,4-bis-(4-hydroxyphenyl)-2-methyl-bu~ane, 1,l~bis-(4-hydroxy-phenyl)-cyclohexane, ~,~-bis-(4-hydroxyphenyl)-p-diiso-propyl-benzene, 2,2-bis-~3-methyl-4-hydroxyphenyl)-propane, 2,2-bis-(3-chloro-4-hydroxyphenyl)-propane, bis-(3,5-dimethyl-4-hydroxyphenyl)-methane, 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane, bis-(3,5-di-methyl-4-hydroxyphenyl)-sulfoxide, bis-(3,5-dimethyl-4-hydroxyphenyl)-sulfone, hydroxybenzophenone, 2,~-bis-(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane, l,l-bis-~3,5-dimethyl-4-hydroxyphenyl)-cyclohexane, a~ -bis-(3,5-dimethyl-4-hydroxyphenyl)-p-diisopropyl-benzene and 4,4' sulfonyl diphenyl.
Examples of particularly preferred flromatic bisphenols are 2,2-bis-(4-hydroxyphenyl)-propane, 2,2-bis-(3,15-dimethyl-4-hydroxyphenyl)-propane and 1,1-. bis-(4-hydroxyphenyl)-cyclohexane.
The most preferred bisphenol is 2,2-bis-(4-~ hydroxyphenyl)-propane (bisphenol-A).
: 25 The polycarbonates of the invention may entail in their structure units derived from one or more of : the suitable bisphenols.
Among the resins suitable in the practice of ; the invention are included phenolphthalic-based poly-carbonate copolycarbonates and terpolycarbonates such as are described in U.S. Patents 3,036,036 and

4,210,741.

Mo-245~

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The polycarbonates of the invention may also be branched by incorporating small quantities of poly-hydroxyl compounds in them by condensation, e.g., 0.05-2.0 mol % (based on the quantity of bisphenols used).
Polycarbonates of this type have been described, for example, in German Offenlegungsschriften 1,570,533;
2,116,974 and 27113,374; Bri~ish Patents 885,442 and 1,079,821 and U.S. Patent 3,544,514. The following are some examples of polyhydroxyl compounds which may be used for this purpose: phloroglucinol; 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl~-heptane-2; 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptane; 1,3,5-tri-(4-hydroxyphenyl)-benzene; l,l,l-tri-(4-hydroxyphenyl)-benzene; l,l,l-tri-(4-hydroxyphenyl)~benzene; 1,1,1-tri-(4-hydroxyphenyl)-ethane; tri-(4-hydroxyphenyl)-phenylmethane; 2,2-bis-[4,4-(4,4'-dihydroxydiphenyl~-cyclohexyl]-propane; 2,4-bis-(4-hydroxyphenyl-4-iso-propyl)-phenol; 2,6-bis-(2'-dihydroxy-5'-methylbenzyl-4-methylphenol; 2,4-dihydroxybenzoic acid; 2-(4-hydroxy-phenyl)-2-(2,4-dihydroxyphenyl)-propane and 1,4-bis-(4'4"-dihydroxytriphenylmethyl) benzene. Some of the other polyfunctional compounds are 2,4-dihydroxybenzoic acid, trimesic acid, cyanuric chloride and 3,3-bis-(4-hydroxyphenyl)-2-oxo-2,3-dihydroindole.
In addition to the polycondensation process mentioned above and which essentials are described below~ other processes for the preparation of the poly-carbonates of the invention are polycondensation in a homogeneous phase and transesterification. The suitable processes are disclosed in U.S. Patents 3,028,365; 2,999,846; 3,153,008 and 2,991,273.

Mo-2456 j, . .'~, The preferred process for the preparation of polyrarbonates is the in~erfacial polycondensation process.
Other methods of synthesis in forming the polycarbonates of the invention such as disclosed in U.S. Patent 3,912,688 may be used.
Suitable polycarbonate resins are available in commerce, for instance, under the tradename Merlon*
M-39, Merlon* M-40 and Merlon* M-50, all of which are bisphenol-A based pulycarbonate resins differing in their respective molecular weights and characterized in that their melt indices per ASTM D-1238 are 12-24, 6-11.9 and 3.0-5.9 gm/10 min., respectively, all availa-ble from Mobay Chemical Corporation of Pittsburgh, Pennsylvanla.
Graft Copolymers In the context of the present practice, graft copolymers are ABS (acrylonitrile-butadiene-styrene~
resins prepared by either bulk or bulk (~ass) sus pension polymerization (as distinguished from similar resins prepared by emulsion polymerization) charac-terized in that their polybutadiene content is about 1 to 25% by weight, preferably 3 to 20% by weight, and in that its average particle size is greater than 0.75, preferably bet~leen 0.8 to 15 microns.
Essentially, the molecules of ABS graft poly-mers consist of two or more polymeric parts of dif-ferent compositions chemically united. The graft poly-mers may be prepared by polymerizing at least one con-jugated diene, such as butadiene or a conjugated diene~ith a monomer polymerizable therewith, such as * Trademark Mo-2456 ~ ' ~'~ L3..

~2~

styrene, to provide a backbone, with subsequent polymer-iza~ion of at least one grafting monomer, and prefer-ably two, in the presence of the prepolymerized backbone to complete the graft polymer.
The backbone9 as mentioned, is preferably a conjugated diene polymer or copolymer such as polybuta-diene, butadiene-styrene, butadiene-acrylonitrile or the like.
A specific conjugated diene monomer which may be utilized in preparing the backbone of the graft polymer is generically described by the formula:
X ~ x x ~ X
C = C - C = C

wherein X may be selected from the group consisting of hydrogen, alkyl groups containing from one to five carbon atoms, chloro and bromo. Examples of dienes that may be used are butadiene; isoprene; 1,2-hepta-diene; methyl-1,3-pentadiene; 2,3-dimethyl-1,3-buta-diene; 1,3-pentadiene; 2-methyl-3-ethyl-1,3-butadiene;
2-ethyl-1,3-pentadiene; 1,3- and 2,4-hexadienes, chloro- and bromo-substituted butadienes such as dichlorobutadiene, bromobutadiene, chloroprene, dibromo-butadiene, mixtures thereof and the like. The preferred conjuga~ed diene utilized herein is buta-diene.
The first monomer or group of monomers polymerized in the presence of the prepolymerized backbone are preferably monovinyl aromatic hydro-carbons. The preferred monovinyl aromatic monomers utilized are generically described by the formula:

Mo-2456 :, Y y - 8 Y~l--C\Y

wherein Y may be selected from the group consisting of hydrogen 9 alkyl groups containing from 1 to 5 carbon atoms, chloro and bromo. Examples of the monovinyl aromatic compounds and substituted monovinyl aromatic compounds that may be used are styrene and other vinyl-substituted aromatic compounds inclucling alkyl-, cyclo-, alkyl-, aryl-, alkaryl-, aralkyl-, alkoxy-, aryloxy-, and other substituted vinyl aromatic compounds. Examples of such compounds are 3-methyl-styrene; 3,5-diethylstyrene and 4-n-propylstyrene, ~methylstyrene, ~-methylvinyltoluene, ~-chlorostyrene, vinyltoluene, ~-bromostyrene, chlorophenyl ethylenes, dibromophenyl ethylenes, tetrachlorophenyl ethylenes, l-vinylnaphthalene, 2-vinylnaphthalene, mixtures ; thereof and the like. The preferred monovinyl aromatic hydrocarbon used herein is styrene and/or ~-methyl-styrene.
The second group of monomers that are polymer-ized in the presence of the prepolymerized backbone are acrylonitrile, substituted acrylonitrile and/or acrylic acid esters exemplified by acrylonitrile and alkyl acrylates such as methylmethacrylate. The acrylo~
nitrile, substituted acrylonitrile or acrylic acid esters are described generically by the formula:

S~
~, ~C - C - z Mo-2456 , ' ~3~3~
~9--wherein S may be selected from the group consisting of hydrogen, alkyl groups containing from 1 to 5 carbon atoms, chloro and bromo and Z is selected from the group consisting of cyano and carbalkogy wherein the alkyl group of the carbalkoxy group contains from 1 to about 12 carbon atoms. Examples of monomers of this description, i.e., acrylonitrile, substituted acrylo-nitrile, or acrylic acid esters of the above formula are acrylonitrile, ethacrylonitrile, methacrylonitrile, a-chloroacrylonitrile, ~-chloroacrylonitrile, ~-bromo-acrylonitrile and ~bromoacrylonitrile, methacrylate, methylmethacrylate, ethylacrylate, butylacrylate 3 propylacrylate, isopropylacrylate, isobutylacrylate, mixtures thereof and the like. The preferred acrylic monomer used herein is acrylonitrile and the preferred acrylic acid esters are ethylacrylate and methylmeth-acrylate.
In the preparation of the graft polymer, the conjugated diolefin polymer or copolymer exemplified by 1,3-butadiene polymer or copolymer comprises 1 to 25%
by weight, preferably 3% to 20% by weight, of the total graft polymer composition and the monomers polymerized in the presence of ~he backbone e~emplified by styrene and acrylonitrile comprise about 75 to 99%, preferably 80 to 97% by weight~ of the total graf~ polymer compo-sition.
Essentially, the ABS resins of the invention, described more fully in U.S. Patent 3,852,393, are obtained by dissolving a butadiene type rubber, such as polybutadiene or a butadiene-styrene copolymer, in a mixture of a vinyl cyano compound represented, for Mo-2456 1()-example, by acrylonitrile and a vinyl aromatic hydro-carbon (including a halogenated compound~ represented by styrene, polymerizing the mixture substantially under bulk polymerization conditions, although a small amount of ~ater can be present in some cases t under sufficiently high agitation so as to shear the rubber being precipitated as polymerization advances until 1 to 40~ by weight of vinyl cyano compound and vinyl aromatic compound are polymerized.
In the case of bulk suspension, water and a suspension stabilizer are then added to the polymer-iza~ion system whereas in the case of the bulk process, the polymerization continues to a predetermined degree.
Among the grafts suitable in the present context is an ABS resin available as Dow ABS Resin* 213 from Dow Chemical Company, of Midland, Michigan - see below a table summarlzing its characteristlc proper-ties.

*Trademark Mo-2456 ~f,~

;23~3 Property ASTMInjection MethodMolded Yield ~ensile Strength lbf/in D-6384,300 Ultima~e Tensile Strength lbf/in D-6385,000 Yield Elongation, ~ D-638 2 Ultimate Elongation, % D-638 50 Tensil~ Modulus lbf/in D-638360,000 Izod Impa~t Strength, ft lbf/in of Notch @ i30F D-256 1.8 @ 0F 1.2 @ -40F 1.0 Vicat Softening Point F D-1525 216 Deflection Temperature 2 Annealed F @ 264 lbf/in D 648 200 Flexur~l Strength, lbf/in D-7909,500 Flexur~l Modulus, lbf/in D-790380,000 Hardness, Rockwell R D-785 1705 L
Specific Gravity D-792 1.05 Linear Coefficient of Ther- 5 mal Expansion, In/In/F D-6965 x 10 Melt Flow Rate, Cond. I
g/10 min. D-1238 5.5 Particle size range, microns 0.5-10 average microns ~3 Mo-2456 ~3~23~

The Impact Modifyin~ Graft In the context of the present invention, the impact modifying graft is a rubber elastic based graft copolymer characterized in that its glass transition temperature is below 10C, preferably below O~C, and in that elastomeric content is about 15 to 98%, preferably from about 20 to about 95~ by weight and in that its average particle size is less than 0.75 micron.
In the preferred grafts, a monomer mixture phase of from 95 to 50% by weight of styrene, methyl-methacrylate or mixtures thereof and from 5 to 50% by weight of acrylonitrile is graft polymerized onto a rubber. In principle, any rubber may be used as the graft backbone so long as its properties meet the criteria set out above. Cross-linking of the rubber elastic phase is an optional feature of the impact modifier graft.
Particularly suitable rubbers are polybuta-diene, butadiene/styrene copolymers having up to 30% by weight of copolymerized styrene, copolymers of buta-diene and acrylonitrile with up to 20% by weight of a lower alkyl ester of an acrylic or a methacrylic acid for example, methylacrylate, ethylacrylate, methylmeth-acrylate and ethylmethacrylate or an acrylate based rubber such as Cl-C6-alkyl acrylate, preferably a butylacrylate.
The weight ratio of rubber to graft polymerized monomers is generally within the range of from 85:15 to 40:60 and the impact modifier graft must be present in the molding composition in the form of particles which diameters may range from about 0.01 to Mo 2456 about 5 microns provided, however, that the average value is less than 0.75 microns.
Graft polymers of this kind are known. They are obtained, for example, by polymeriging the monomers on a rubber latex in the presence of a radical catalyst, and are available in commerce from for in-stance, Bayer AG of Leverkusen, West Germany.
~ mong the acrylate based grafts are the multi-phase acrylic rubber interpolymer composites described in U.S. Patents 3,808,180 and 4,096,202. Briefly, the technology described therein is that of the preparation of a specific class of multiphase compounds. These are compositions comprising about 25 to 95% by weight o-f a first elastomeric phase and about 75 to 5~ by ~eight of a second, rigid, thermoplastic phase. The first phase is polymerized from about 75 to 99.8~ by weight Cl-C6-acrylate resulting in an acrylic rubber core having a glass transition temperature below about 10C, which is cross-linked with 0.1 to 5~ by ~leight of a cross-linking monomer and to which is added 0.1 to 5 by weight of a graft-linking monomer.
The preferred alkyl acrylate is butyl-acrylate. The cross-linking monomer is a polyethyleni-cally unsaturated monomer having a plurality of ad-dition polymerizable reactive groups all of whichpolymerize at substantially the same rate of reaction.
Suitable cross-linking ~onomers include polyacrylic and polymethacrylic esters of polyols such as butylene diacrylate and dimethacrylate, trimethylol propane trimethacrylate and the like; di- and trivinyl benzene, vinyl acrylate and methacrylate, and the like. The Mo-2456 ~,.....

preferred cross-linking monomer is butylene diacrylate. The graft-linking monomer i5 a polyethylen-ically unsaturated monomer having a plurality of addition polymerizable reactive groups, at least one of which polymeri~ing at a substantially different rate of polymerization from at least one other of said reactive groups. The function of the graft-linking monomer is to provide a residual level of unsaturation in the elastomeric phase, particularly in the latter stage of lo polymerization and, consequently, at or near the surface of the elastomer particles. The preferred graft-linking monomer is allyl methacrylate and diallyl maleate.
The final stage monomer system can be comprisecl of Cl-C6-methacrylate, styrene, acrylo-nitrile, alkyl acrylates, alkyl methacrylate, dialkyl methacrylate and the like, as long as the over Tg is at least 20C. Preferably, the final stage monomer system is at least 50% by weight Cl-C4-alkyl meth-acrylate. It is ~urther preferred that the final statepolymer be free of units which tend to degrade poly(alkylene terephthalate); for example, acid, hydroxyl amino and amide groups.
A certaln such acrylic rubber interpolymer composite characterized in that acrylic rubber core is comprised of n-butyl-acrylate and in that its cross-linking agent is 1,3-butylene diarylate and in which ; the graft-linking agent is diallyl maleate and the second phase monomeric system of which is methyl meth-acrylate is noted to be particularly suitable in the present context.

Mo-2456 :

The compositional makeup of the preferred interpolymer compound is described by the weight ratios of its constituent monomers as follows: n butyl-acrylate/1,3-butylene diacrylate/diallyl maleate/methyl-methacrylate - 79.2/0.4/0.4/20Ø
A suitable acrylic rubber interpolymer com-posite is available under the tradename Acryloid* KM-330 from Rohm ~ Haas Company of Philadelphia, Pennsyl-vania.
The thermoplastic molding compositions of ~he invention comprise a blend containing 20 to 95 phr of polycarbonate resin, 3 to 78 phr of the graft copolymer and a 2 to 40 phr of the impact modifying graft; a corresponding preferred set of ranges is 30 to 80 phr of polycarbonate, 10 to 60 of the graft copolymer and 5 to 30 of the impact modifying graft.
:[n addition to the components of the compo-sition of the invention, as noted above, the compo-sition may contain mold release agents, pigments, dies, flame retardants, stabilizers to heat and moisture as well as fillers and reinforcing agents of the types known in the art.
The preparation of the composition of the invention follows a procedure comprising dry blending of the ingredients followed by extrusion and pel-letizing by means well established in the art and ex-emplified below.
The invention will be illustrated but is not intended to be limited by the Examples below. In all the examples described below, except where noted other wise, the graft polymer was Dow ~BS resin 213 and the polycarbonate resin was a bisphenol-A homopolycarbonate *Trademark Mo 2456 F~,7 ~;~3~

having a melt flow index of about 6 to 11.9 gm/10 min.
Also, the polybutadiene based impact modifiers iden~ified as A, C, D and G used in the examples below were characterized in that their glass transition temperature is -85C and in that their average particle size is below 0.4 microns.
EXAMPLES
Examples 1-7 Compositions in accordance wlth the invention were prepared and their properties determined as is summarized below in Table 1. The blended components were extruded (2" MPM-Extruder, Compression ratio 2.75:1, screen pack 20-40-60-20~ at a temperature profile (rear to front): 270/280/270/255/245/265/
265C. The compositions were injection molded into test specimens at 450F. In addition to the components noted in the Table, a thermal stabilizer described generally in DOS 2,929,229 was incorporated in the composition at a level of 0.2~. No criticality in the context o~ the present invention is assigned to the addition of said stabilizer.

Mo-2456 ~,, 3~

TA~3LE 1 Control Polycarbonate, pbw60.060.060.060.060.060.0 60.0 Graft polymer, pbw40.035.030.025.035.030.0 25.0 Impact modifier, pbw c~ 5.010.015.0 -- ~
D!2) __ __ __ -- 5.0 10.0 15.0 Melt index, gm/
10 min. 13.2 10.7 9.39.5 11.3 10.6 8.4 Gloss( ) low low low low low low some Impact strength, Izod-Notched 1/8" r.t. 11.414.013.2 12.1 13.5 13.3 11.9 -20C 2.6 3.4 4.97.6 6.8 7.3 8.q ~30C 1.9 2.9 3.73.8 3.1 7.1 6.5 -40C 2.1 2.3 2.92.~3 3.4 3.5 4.7 Heat deflection temperature at 26q psi, C 109.4 111.1109.6104.510~.8111 103.9 (1) C denotes a graft consisting of 20~
polybutadiene and 80~ SAN (So~N ratio 72/28) (2) D denotes a graft ccnsisting of 50% poly-butadiene grafted with 50~ S~N (S/~N ratio 72/28) (3) determined by observation.

Mo-2456 ~3~3~

Compositions in accordance with the invention were prepared and their properties determined as is summarized below in Table 2. The blended components were extruded (2" MPM-Extruder; compression ratio 2.75:1, screen pack 20-40-60-20) at a temperature profile of (rear to front) 270/280/270/255/245/265/
265C. The compositions were injection molded into test specimens at 450F except as noted below. All the compositions were noted to yield specimens character-ized by their low gloss.

~10-2456 T~BLE 2 Control Polycarbonate, pbw 60.0 60.060.0 63.1550.0 50.050.050.0 Graft polymer, pbw 30.0 25.030.0 26.3237.5 32.037.532.0 Impact modifier, pbw A( ) 10.0 15.0 ~ 12.5 18.0 -- --B( ) -- -- 10.0 10.53 -- -- 12.518.0 Melt index 6.9 5.26.7 5.9 6.9 4.7 6.8 6.2 Impact s-trength, notched Izod ft. lb/in.
Specimen~ tested at room temperature Specimens molded at 450F 1/8" 15.8 16.013.6 12.2 12.3 13.711.710.8 1/4" 10.7 10.710.3 9.7 12.0 9.710.3 8.9 475F 1/8" 12.6 13.612.3 10.8 16.2 13.811.910.2 1~4" 10.0 10.89.9 9.7 10.9 9.8 8.9 8.2 500F 1/8" 13.0 12.612.4 10.9 12.4 12.910.810.4 l/4~ 10.1 10.59.8 9.8 9.7 9.9 9.0 8.6 525F 1/8" 12.1 12.311.6 11.2 13.3 11.910.9 9.5 1/4" 10.3 10.59.5 9.3 9.8 9.9 7.8 7.9 Tested at:
1/8" -20C 7.9 9.68.2 8.4 8.9 8.8 7.2 7.0 -30C 5.8 8.36.0 7.6 6.6 7.6 6.8 5.4 -40C 3.8 7.25.4 6.7 3.4 5.9 4.0 4.8 Mo- ~4 5 6 ;;
~' 3~

-- ~o --TABLE 2-Cont ' d Control Heat deflection temperature, C, at 264 psi 115.2 115.1 119.0 116.5 107.0 106.7 109.2 109.8 (1) A denotes a graft consisting of 80% polybutadiene grafted with 20% SAN (S/AN ratio being 72/28), the average particle size is about 0.3 to 0.5 microns.
~2) B denotes Acryloid KM-653 which is an MBS System (methylmethacrylate butadiane-styrene copolymer); a product of Rohm & Haas, character-ized in that the Tg of the rubber phase is below -50C.

Mo-2456 3~31 The compositions noted below were prepared and tested in much the same way as was described above.
Excep~ for composition 19, a small amount (0.3 pbw) of a thermal stabilizer of the type described in DOS
2,929,229 was added to the compositions. No criticality is ascribed to that addition in the present invention.

Mo-2456 ~3~ ,3~

Control 16 17 18 19 Polycarbonate, pbw 60.0 60.0 50.0 50.0 Graft polymer, pbw 30.0(a) 40.0( ~ 37.5( ) 37.5( ) Impact modifier D(2), pbw 10.0 - 12.5 12.5 Melt index, gm/10 min. 9.2 very high 10.0 9.4 Gloss some high somevery low Heat deflection temperature at 26~l psi, C 114.5 113.1 103.2 104.3 Impact strength, Izod notched, ft.lb/in.
1/8'i r.t.16.3 12.4 15.6 12.4 -20C 9.7 3.8 7.1 9.5 -30C 6.2 1.3 3.6 4.8 -40C 2.9 1.1 2.4 2.7 tl) Novodur* PK - Emulsion ABS, containing 30% poly-butadiene and 70% SAN (S/AN = 72/28), particle size average about 0.4 microns, Tg of the rubber phase is -85C, Commercial Product of Bayer AG.
(2) An impact modifier graft consisting of 50% poly-butadiene and 50% SAN (S/AN = 72/28).
~a) Dow Chemical ABS resin, 213.

* Trademark Mo-2456 ,~

As may be readily appreciated, the addition of the impact modifiers of the invention have a most profound effect on the low temperature impact performance of the blends of polycarbonate and graft polymer. This is particularly unexpected in view of the decline, or at best the marginal improvement, in room temperature impact strength of these compositions.
The compositions of the invention are further noted to be of a characteristically low gloss.

Further compositions in accordance with the invention were prepared and their properties determined as noted below. The blended components were extruded (ZSK 53, 100-110 rpm, 90~100 lbs/hr) at a temperature profile (rear to front): 270/250/235/240/235/240C.
The compositions were injection molded at 450F except as noted.

Mo-2456 ~3~;23~

~ABLE 4 Control 20 2122 23 24 Polycarbonate, pbw 60.0 60.0 60.0 60.0 52 60 Graft polymer, pbw 40.0 30.0 30 0 __ 48(1) 30 Impact modifier, pbw G (3~ lO.o -_ __ __ __ D ( -- -- 10.024.0 -- --SAN CN 51 ) -- -- --16.0 -- --Polybutadiene content (%) 3.2 9.9 7.412.0 9.0 2.4 Melt Index ~gm/10 min.)12.9 7.5 8.7 6.0 5.2 9.0 HDT a-t 264 psi, C 110.3109.5112.7115.2 113.6 111.2 Gardner impact, in. lb.
room temperature 440 380395354 363 368 a~ -29 292 290 330339344 288 Gloss (60) ~52 45 61.995.6 95.5 68 Ultimate elongation, % 70.0 120.0120.0100.030.0 110 Notched Izod Impact (ft.lb./in.) specimens tested at room temperature Molded at 450F, 1/8"11.6 13.1 13.211.8 11.3 12.7 1/4" 9.2 10.5 10.410.0 9.2 9.8 475F, 1/8"11.7 12.5 12.811.5 11.3 15.9 1/4" 9.0 10.4 10.5 9.3 8.9 10.4 500F, 1/8"11.3 11.9 12.210.8 9.9 12.3 1/4" 8.8 10.0 10.5 9.4 7.4 11.3 Mo-2456 ~3~

TABLE 4 - Cont.
Control 20 21 22 23 24 525F, 1/8"11.8 11.2 llo9 10~0 8~012~1 1/4"8.7 9.9 g.9 ~.3 3.111.0 Notched Izod in.lb./ft.
1/8" at ~20C 2.3 12.6 9.9 9.1 7.2 7.5 at -30C1.7 10.8 8.2 7.5 2.7 5.2 at -40C1.3 4.8 5.7 7.9 2.4 3.5 (1) Blendex* 206 - Emulsion ABS, a product of Borg-Warner - characterized in that its average particle size is about 0.1 - 0.2 microns and in that its polybutadienP content is about 18%.
(2) SAN CN Sl - styrene acrylonitrile copolymer - a product of Monsanto having a S/AN ratio of about 3:1.
(3) denotes an impact modifier graft containing 75%
polybutadiene grafted with 25% SAN (S/AN - 72/28).
The average particle size is about 0.3 ko 0.5 microns.
(4) denotes an impact modifier graft containing 50%
polybutadiene grafted with 50% SAN (S/AN - 72/28).
The average particle size is about 0.3 to 0.5 microns.

*Trademark Mo-2456 '` L'~

3~3 The results presented in Table 4 clearly indicate that the compositions in accordance with the invention, i.e., 20 and 21 feature an attractive combination of good impact properties, low gloss values and high ultimate elongation as compared with either the control or with compositions 22 and 23.
Although the invention has been described in d~tail in the foregoing for the purpose of illustra-tion, it is to be understood that such detail is solely for that purpose and that variations can be made there-in by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.

Mo-2456

Claims (9)

The embodiments of the invention in which exclusive property or privilege is claimed are defined as follows:

1. A thermoplastic molding composition com-prising a blend of (i) an aromatic polycarbonate resin, (ii) an acrylonitrile butadiene styrene graft copolymer characterized in that its polybutadiene content is about 1 to less than 20% relative to its weight and in that its average particle size is greater than 0.75 micron and (iii) an impact modifying graft consisting of a rubber elastic phase and a grafted on phase charac-terized in that its glass transition temperature is less than 10°C and in that the content of its elast-omeric phase is 15% to 98% relative to its weight and in that its average particle size is less than 0.75 micron.

2. The composition of Claim 1 wherein said (i) is present at an amount of from 20 to 90%, said (ii) is present at an amount of from 3 to 78% and said (iii) is present at an amount of from 2 to 40%, said percents being in relation to the weight of said blend.

3. The composition of Claim 2 wherein said (i) is a bisphenol-A based on polycarbonate resin.

4. The composition of Claim 2 wherein said (ii) is characterized in that its polybutadiene content is about 3 to less than 20% by weight.

5. The composition of Claim 4 wherein said (ii) is further characterized in that its said average particle size is between 0.8 and 15 microns.

6. The composition of Claim 1 wherein said (iii) is characterized in that its glass transition temperature is below 0°C.

7. The composition of Claim 1 wherein said (iii) is characterized in that said content of said elastomeric phase is about 20 to 95% by weight.

8. The composition of Claim 6 wherein said temperature is less than -50°C.

9. A thermoplastic molding composition com-prising a resinous blend of (i) 30 to 80 phr of an aromatic polycarbonate resin, (ii) 10 to 60 phr of an acrylonitrile butadiene styrene graft copolymer charac-terized in that its butadiene content is about 3 to less than 20% by weight and in that its average particle size is about 0.8 to 15 microns and (iii) 5 to 30 phr of an impact modifying graft consisting of a rubber elastic phase and a grafted-on phase characterized in that the glass transition temperature of the rubbery phase is less than -50°C and in that the content of its rubbery phase is about 20 to about 95% relative to the weight and in that its average particle size is less than 0.75 microns.