CA2056481A1 - Blow-moldable polycarbonate resin compositions of high impact strength - Google Patents

Abstract

BLOW-MOLDABLE POLYCARBONATE RESIN COMPOSITIONS
OF HIGH IMPACT STRENGTH

ABSTRACT OF THE DISCLOSURE
Processing of blow-moldable, branched polycarbonate resin is enhanced by the addition of a SAN copolymer processing modifier to the base resin. An impact modifier such as ABS resin is also present.

Description

BLOW--MOLDABLE POLYCARBONATE RESIN COMPOSITIONS
_~ ___ OF ~ GH IM~.ACT STRENGTH
BACRGROUND OF THE I ~ NTION
Field of the Invention ~ he invention relates to thermoplastic resin compositions and ~ore particularly relates to improved, blow-moldable polycarbonate resin compositions and artieles molded therefrom.
Brief Description of th~e ~ior Art Aromatic polycarbonate resins are a well known class of synthetic polymeric resins, generally prepared by the reaction of a polyhydric phenol with a carbonate precursor: sae for exa~ple U.S. Patent 3,989,672. Although such polycarbonate resins have been found to be thermoplastically moldable under a broad range of molding conditions, only select polycarbonate resin co~positions ar~ cuitable for blow-molding. Thi~ is due to the unique requirements of a ther~oplastic resin for blow-molding operatio~.
In the conventional blow-molding operation, a tube of the heat-softsned polycarbonate resin may be extruded vertically into a mold. The extrudate is then pressed unto ths ~old ~urfaces with a pressurized gas fl~w (usually air or inert gas), shaping the heat-softened resin. As appreciated by ~hose skilled in the art, the successful molding of a given thermoplastic resin is dependent upon a number of factors, including the characteristics and physical propertie~ o~ the heat-softened resin.
Among so~tened resin properties to be con~idered are the melt vi~cosity and the ~elt strength of the . .

resin. These two factors alone are of consider~le importance in the successful blow-moldina _l any resin, particularly in regard to t~- molding of large articles.
Many aromatic pOly~arbonate resins are eminently useful in blOw-m~laing operations because they meet the nec~s~ry requirements of melt viscosity, melt strength and other desirable physical properties.
Branched polycarbonate resins such as those described in the U.S. Patents 4,101,184 and 4,474,999 are particularly useful ~or blow-molding, having many o~ the desirable physical properties.
However, blow-molding the branched polycarbonate resin compositions has not been completely - satisfactory in all respects. In particular, many of the prior art compositions may have an inherent lack of a relatively high melt strength coupled with a relatively low melt viscosity. Resin additiv~s are known, such as amine types of aliphatic esters, which when admixed with many branched polycarbonate resins will lower the melt viscosity of the composition. ~owever, the additives generally degrade polycarbonate resin, and the molded articles consequently exhibit lowered impact strength.
We have found that blow moldable polycarbonate resin compositions containing a thermoplastic copolymer of a styrenic monomer and an acrylonitrlle monomer in addition to a conventional impact modifier, can be blow-molded to obtain articles exhibiting high impact strength. Most importantly the compositions possess a high melt strength, but also respond to shear-thinning, i.e.; under thermo-. ` `
: . . ` ` : ' .

processing conditions they exhibi~ low meltviscosities.
The improved processability is obtained without a significant loss of other properties in thC molded articles prepared from the compositio~o of the invention. In ~act, in some instances the property of impact strength may sho~ improvement.
SUMMARY OF THE INVENrION
The invention comprises blow-molding resin compositions, which comprise;
a blow-moldable, branched polycarbonate resin;
a processability-modifying proportion of a copolymer of a styrenic monomer and an acrylonitrile monomer: and an impact-modifying proportion of a polycarbonate impact modifier.
The invention also comprises articles blow-molded from compositions of the invention. The articles of the invention are useful as bottles, tool housings, automotive components and the like.

EMBODIMENTS OF THE INVENTION
Blow Moldable, branched polycarbonate (PC) resins are generally well known and may be prepared by reacting a dihydric phenol and a polyfunctional organic compound with a~carbonate precursor, such as phosgene, a haloformate or a carbonate ester.
Generally speaking, such carbonate polymers may be typified as possessing recurring structural units of the formula:

~ O - D - O - C 3 (I) .
.

.. . . . . . . . . . .

~3 ~.1 !3 J

wherein D i~ a divalent aromatic radical, residue of the dihydric phenol employed in the polymerization reaction. Occasional branch moieties occur als~ in the polymer chain bearing residues of the polyfunctional organic compound. The ~ethod of preparation is well known; see for example the inter~acial polymerization met~od described in U.S.
Patents 4,001,18~ and ~,474,999, both of which are herein incorporated by reference.
In general, the method of interfacial polymerization comprises the reaction o~ the dihydric phenol with a carbonyl halide (the carbonate precursor~ and the polyfunctional organic compound.
Although the reaction conditions of the preparative processes may vary, several o~ the preferred processes typically involve dissolving or dispersing the dihydric phenol and polyfunctional organic compound reactants in aqueous caustic, adding the resulting mixture to a suitable water immiscible solvent medium and contacting the reactants with the carbonate precursor, such as phosgene, in the presence of a suitable catalyst and under controlled pH conditions. The most commonly used water immiscible solvents include methylene chloride, 1,2-dichloroethane, chlorobenzene, toluene, and the lik~.
The catalyst employed accelerates the rate of polymerization of the dihydric phenol reactant with the carbonate precursor. Representative catalysts include but are not limited to tertiary amines such as triethylamine, quaternary phosphonium compounds, guaternary ammonium compounds, and the like. The .. .
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.

- 2 ~ 5, ~

preferrod process ~or Pre~aring polycarbonate resins used in the invention comprises a phosgenation reaction. The temperature at which the phosa~ n reaction proceeds may vary from belo~ o C, to above 100C. The phosgenation reaction preferably proceeds at temperatur~ of from room temperatures (25C) to 50C. slnce the reaction is exothermic, the rate of phosgene addition may be used to control the reaction temperature. The amount of phosgene required will generally depend upon the amount of the dihydric phenol and the amount of polyfunctional organic compound present.
The dihydric phenols employed are known, and the reactive groups are the two phenolic hydroxyl groups. Some of the dihydric phenols are represented by the general fo~mula:
~ (X)4 ~ ~X) H0 ~ A ~

(II) wherein A is a divalent hydrocarbon radical containing from l to about 15 carbon atoms; a substituted divalent hydrocarbon radical containing from l to about 15 carbon atoms and substituent groups such as halogen;
-S- ; -S-S- ; -S(=0)- ; -S(=0)2- ; -0- : or -C(-0)- ;
wherain each X is independently selected from the group consisting of hydrogen, halogen, and a monovalent hydrocarbon radical such as an alkyl group of ~rom l to about 8 carbon atoms, an aryl group of from 6-l8 carbon atoms, an aralkyl group of from 7 to about 14 carbon atoms, an alkaryl group of from 7 to about 14 carbon atom~, an alkoxy group of - , : , . , ,. . , :

~ 3~ :3L

8CL-~838 from 1 to about 8 carbon ato~s, or an aryloxy group of from 6 to 18 carbon atoms; and wherein m is zero or 1 and n is an integer of from 0 to 5.
Typical of some of the dihydric phenols that can be employed in the practice of the present invention are bis-phenols such as (4-hydroxy-phenyl)methane, 2,2-bis(4-hydroxyphenyl)propane (also known as bisphenol-A), 2,2 bis(4-hydroxy-3,5-dibromophenyl)propane; dihydric phenol ethers such as bis(4-hydroxyphenyl) ether, bis(3,5-dichloro-4-hydroxyphenyl) ether; dihydroxydiphenyls such as p,p' dihydroxydiphenyl, 3,3'-dichloro-4,4'-dihydroxydiphenyl; dihydroxyaryl sulfones such as bis(4-hydroxyphenyl) sulfone, bis (3,5-dimethyl-4-hydroxyphenyl) sulfone~ dihydroxybenzenes such as - resorcinol, hydroquinone, halo- and alkyl-substituted dihydroxybenzenes such as 1,4-dihydroxy-2,5-dichlorobenzene, 1,4-dihydroxy-3-methylbenzene;
and dihydroxydiphenyl sul~ides and sulfoxides such as bis(4-hydro~yphQnyl) sul~ide, bis(4-hydroxy-phenyl) sulfoxide and bis~3,5-dibromo-4-hydroxy-phenyl) sulfoxide. A variety of additional dihydric phenols ar~ available and are disclosed in U.S. Pat.
Nos. 2,g99,835; 3,028,365 and 3,153,008; all of which are incorporated herein by reference. It is, of course, possible to ~ploy two or more dif~erent dihydric phenols or a combination of a dihydric phenol with glycol~
The carbonate precursor can be either a 30 carbonyl halide, a diarylcarbonate or a bishalo-- -formate. The carbonyl halides include carbonyl bromide, carbonyl chloride, and mixtures thereof.
The bishaloformates include the bishaloformates of . .
,.

.: .
.
. .
- . ~ ... :

3 ~

dihydric phenols ~uch as bischloroformates of 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, hydroquinone, and th~ like, or bishaloformates o~ glycols such as bishalo-formates of ethylene glycol, and the like. Whileall of the above carbonate precursors are useful, carbonyl chloride, also known as phosgene, is preferred.
Branching results ~rom th~ inclusion of the polyfunctional organic compound, which is a branching agent. The polyfunctional organic compounds are generally well Xnown, aromatic and contain at least three functional groups which are carboxyl, carboxylic anhydrides, phenol~, haloformyls or mixtures thereof. Some nonlimiting examples of these polyfunctional aromatic compounds include l,l,l-tri(4-hydroxyphenyl) ethane, trimellitic anhydride, trimellitic acid, trimellitoyl trichloride, 4-chloroformyl phthalic anhydride, pyromellitic acid, pyromellitic dianhydride, mellitic acid, mellitic anhydride, trimesic acid, benzophenonetetracarboxylic acid, benzophenonetetracarboxylic anhydride, and the like.
The preferred polyfunctional aromatic compounds are ~5 l,l,l-tri~4-hydroxyphenyl)ethane, trimellitic anhydride or trimellitic acid or their haloformyl derivatives.
Also included herein are blends of a linear polycarbonate and a branchad polycarbonate.
The aromatic carbonate branched polymers for use as a component of the compositions of the invention include polyester-carbonates, also known a copolyester-polycarbonates, i.e., resin~ which , , contain, in addition to recurring polycarbonate chain units oP the formula (I), given above, repeating or recurring carboxylate units, for example of the ~ormula:
~ O-C(=O)-R1-C(-O)-O D~
wherein D is as defined above a~d Rl~s as defined below.
In general ~he copolyester-polycarbonate resins are prepared as d~cribed above for the preparation of polycarbon~te homopolymers, but by the added presence o~ a dicarboxylic acid (ester precursor) in the water immiscible solvent.
In general, any dicarboxylic acid convention-ally used in the preparation of linear polyesters may be utilized in the preparation of the copolyester-carbonate resins of the instant invention. Generally, the dicarboxylic acids which may be utilized include the aliphatic dicarboxylic acids, the aromatic dicarboxylic acids, and the 2Q aliphatic-aro~atic dicarboxylic acids. These acids are well known and are disclosed for example in U.S.
Pat. No. 3,169,121 which is hereby incorporated herein by reference. Representative of such aromatia dicarboxylic acids are those represented by the general formula:
HOOC-RI-COOH
(IV) wherein Rl represents an aromatic r~dical such as phenylene, naph$hylene, biphenylene, substituted phenylene and the like; a divalent aliphatic-aromatic hydrocar~on radical such as an aralkyl or alkaryl radical; or two or more aromatic groups ~;J ~ _i i .~ ~ i connected through non-aromatic linkages of the formula:
- E -wharein E is a dival~nt alkylene or alkylidene group. E may also consist o~ two or more alkylene or alkylidene groups, connected by a non-alkylene or alkylidene group, connected by a non-alkylene or non-alkylidene group, such a~ an aromatic linkage, a tertiary amino linkage, an ether linkage, a carbonyl linkage, a silicon-containing linkage, or by a sulfur-containing linkage such as sulfide, sulfoxide, sul~one and the like. In addition, E may be a cycloaliphatic group o~ five to seven carbon atoms, inclusive, ~e.g. cyclopentyl, cyclohexyl), or a cycloalkylidene of five to sev~n carbon atoms, inclusive, such as cyclohexylidene. E may al o be a carbon-free sulfur-containing linkage, such as sulfide, sulfoxide or ~ul~one; an ether linkage; a carbonyl group; a direct bond; a tertiary nitrogen group; or a silicon-containing linkage such as silane or siloxy. Other groups which E may represent will occur to those skilled in the art.
For purposes of th~ present invention, the aromatic dicarboxylic acids ara preferred. Thus, in the preferred aro~atic difunctional carboxylic acids, R
is an aromatic radical such as phenylene, biphenylene, naphthylene, or substituted phenylene.
Some non-limiting examples of ~uitable aromatic dicarboxylic acids which may be used in preparing the poly(ester-Carbonate) or polyarylate resins o~
the instant invention include phthalic acid, isophthalic acid, terephthalic acid, homophthalic acid, o-~ m-, and p-phenylenediacetic acid, and the .
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polynuclear aromatic acids such as diphenyl dicarboxylic acid, and isomeric naphthalene dicarboxylic acids. The aromatics may be substituted with Y groups. Y may be an inorganic atom such as chlorine, bromine, fluorine and the like; an oxganic group such as the nitro group; an organic group such as alkyl; or an oxy group such as alkoxy, it being only necessary that Y be inert to and unaffected by the reactants and the reaction conditions. Particularly use~ul aromatic dicarboxylic acids are those represented by the general formula: -(R3) HOOC ~
~ ~ COOH
(V)wherein j is a positive whole integer having a value of from 0 to 4 inclusive; and each R3 is independently selected from the group consisting of alkyl radicals, preferably lower alkyl (1 to about 6 carbon atoms).
Mixtures of these dicarboxylic acids may be employed. Therefore, where the term dicarboxylic acid is used herein it is to be understood that this term includes mixtures of two or more dicarboxylic acids.
Most preferred as aromatic dicarboxylic acids are isophthalic acid, terephthalic acids, and mixtures thereof. A particularly useful difunctional carboxylic acid comprises a mixture of isophthalic acid and terephthalic acid wherein the weight ratio of terephthalic acid to isophthalic .
:, C~ ~ ''' I"' ld ~ ~

acid is in the range of from about 10:1 to about 002:9.8.
Rather than utilizing the dicarboxylic acid per se, it is possible, and sometimes even preferred, to employ the reactive derivatives of said acid.
Illustrative of these reactive derivatives are the acid halides. The preferred acid halides are the acid dichlorides and the acid dibromides. Thus, for example instead of using isophthalic acid, texephthalic acid or mixtures thereof, it is possible to employ isophthaloyl dichlori~e, terephthaloyl dichloride, and mixtures thereo~.
The proportions of reactants employed to prepare the copolyester-carbonate resins of the invention will vary in accordance with the proposed use of the product resin. Those sXilled in the art are aware of useful proportions, as described in the U.S. patents referred to above. In general, the amount of the ester bonds may be from about 5 to about 90 mole percent, relative to the carbonate bonds. For example, 5 moles of bisphenol A reacting completely with 4 moles of isophthaloyl dichloride and 1 mole of phosgene would give a copolyester-carbonate of 80 mole percent ester bonds.
The preferred branched polycarbonates for use in the present invention are those derived from bisphenol A and phosgene and having an intrinsic viscosity of 0.3 to 0.75 deciliters per gram, measured in methylene chloride at 25 C.
In general, blow-moldable polycarbonate basPd resins will have an R* value within the ranqe of from about 1.4 to about 10Ø Relatively small moldings are advantageously blow-molded from resins having an R* value below about 4.3 while larger ,: . - : -, '' ' `' ' ' . 3 moldings (on the order of about 4-20 Kg) will have R* values above 5Ø The R* value is an indication of blow~moldability of a composition and may be calculated as follows:
STEP 1 - Generate viscosity (~ and elastic modulus (G') da~a on test compositions at three tempera~ures, with a rotational rheometer such as the RD5 7000, (Rheometrics Inc.).
STEP 2 - Using the data ~rom STEP 1 fitted to the Arrhenius type equations, calculate optimum melt temperature for parison extrusion ti.e., the temperature required to yield a malt viscosity of 20,000 poise at 100 sec~l).
STEP 3 - Calculats the ratio of viscosity at low shear rate (1 sec 1 nominal) to viscosity at 100 sec 1 ~20,000 poise), R*, at temperature estimated in STEP 2. Elastic modulus values (@ 1 sec 1) are also calculated at this temperature.
The copolymer of styrenic monomer and an acrylonitrile monomer is added to the polycarbonate in a processability-modifying proportion.
The term "processability-modifying proportion"
as used herein means a proportion of the processing modifier sufficient to enhance the shear-thinning property of the polycarbonate, when melted. In general, such a proportion is within the range of from about 5 to about 30 parts by weight of the total molding composition polymers.
In accordance with the present invention, a copolymer of a styrenic monomer and an acrylonitrile monomer employed as components of resin blends o~
the invention include those sometimes referred to in the art as "SAN types of polymers"~ Th~ "SAN types of Polymers" are a wide variety of polymPrs, the molecules of which contain two or more monomeric . .

.

`3 8CL-6~33~

parts that are copolymerized. One monomer or group of monomers that may be co-polymerized and referred to above as styrene types of monomer are monovinylaromatic hydrocarbons. The monovinylaromatic monomers may be generically described by the formula:
X X
X ~/~--C C~
X ~ X

(VI) wherein each X is independently selected from the group consisting of hydrogen, alkyl of 1-5 carbon atoms, chlorine or bromine. Examples of the monovinylaromatic compounds and alkyl-, cycloalkyl-, aryl-, alkaryl-, aralkyl-, alkoxy-, aryloxy-, and other substituted vinylaromatic compounds include styrene, 4-methyl- styrene; 3,5-diethylstyrene, 4-n-propylstyrene, ~-methylstyrene; ~-methyl-vinyltoluene, ~-chlorostyrene, ~-bromostyrene, dichlorostyrene, dibromostyrene, tetra-chlorostyrene, mixtures thereof, and the like. Thepreferred monovinyl- aromatic hydrocarbons used are styrene and/or ~-methylstyrene and p-methylstyrene.
The second group of monomers, i.e.; the acrylonitrile type that may be polymerized in preparing the SAN type of copolymer are acrylic monomers such as acrylonitrile and substituted acrylonitrile. Minor amounts of acrylic acid esters, or methyl acrylic esters exemplified by alkyl acrylates such as methyl methacrylate may be ,' , .. ..

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1~
present during the polymerization of the SAN type of copolymers used hersin.
The acrylonitrile and substituted acrylonitriles, are described generically by the fo~mula:
X
~ C = C CN
(VII) wherein X i5 as previously definedO Examples of such monomers include ethacrylonitrile, methacrylonitrile, ~-chloroacrylonitrile, ~-chloroacrylonitrile, ~-bromoacrylonitrile, and ~-bromoacrylonitrile.
The most preferred SAN copolymers employed in the ~lends of the invention contain 20-35 percent acrylonitrile segments (by weight) and 80-65%
styrene or alkyl-substituted styrene or mixtures thereof, segments (by weight)~
It is advantageous that the compositions of the invention include an impact-modifying proportion of an impact modifier. Any o~ the known polycarbonate impact modi$iers may be used. Representative of such impact-modifiers are selectively hydrogenated linear, sequential or ~adial teleblock copolymers o~
a vinyl aromatic compound ~A) and (A') n and an olefinic elastomer (B) o~ the A-B-A~: A (B-A-B )nA; A
( B-A )n~; or B [( A-~) B]4 type wherein n is an integer of from 1 to 10 inclusive.
The selectively hydrogenated line r block copolymers are well known as are methods of their preparation, and they are commercially available.
The selectively hydrogenated lineax block copolymers -~ . .
.

are well known and are describad by Hae~ele et al, U.S. Pat. No. 3,333,024, which is incorporated herein by reference.
Prior to hydrogenation, the end blocks of these copolymers comprise homopolymers or copolymers preferably prepared from alkenyl aromatic hydrocarbons and particularly vinyl aromatic hydrocarbons wherein the aromatic moiety may be either mono~yclic or polycyclic. Typical monomers include styrene, alpha methyl styrene, vinyl xylene, ethyl vinyl ~ylene, vinyl naphthalene, and the like, or mixtures thereo~ The end block (A) ~nd (Al), may be the same or dif~erent. They are preferably selected from styrene, ~-m~thyl styrene, vinyl toluene, vinyl xylene, vinyl naphthalene, especially styrene. The center block (B) may be derived ~rom, for example, butadiene, i~oprene, 1,3-pentadiene, 2,3,dimethyl butadiene, and the like, and it may havs a linear, se~uential or teleradial structure.
The ratio of the copolymers and the average molecular veights can vary broadly although the molecular weight center block should be greater than that of the co~bined terminal blocks. It is preferred to form terminal blocks A having weight average molecular weight~ of 2,000 to 100,000 and center block B, e.g., a hydrogenated polybutadiene block with a wei~ht average molecular weight of 25,000 to 1,000,000. 5till more prefera~ly, the terminal blocks may have weight average molecular weights of 8,000 to 60,000 while the hydrogenated polybutadiene polymer blocks have a weight av~rage molecular weight between 50,000 and 300lO00. The terminal blocks will pre~erably comprise 2 to 60~ by , weight, or more, preferably, 15 to 40~ by weight, of the total block co-polymer. The preferred copolymers will be those formed from a copolymer having a hydrogenated/ saturated polybutadiene S center block wherein 5 to 55%, or more, preferably, 30 to 50% of the butadiene carbon atoms, are vinyl side chains.
The hydrogenated copolymers will have the average unsaturation reduc d to less than 20% of the original value. It is preferred to have the unsaturation o~ the center block B reduced to 10%, or less, preferably 5% of its original value.
The block copolymers are formed by techniques well known to those skilled in the art.
Hydrogenation may be conducted utilizing a variety of hydrogenation catalysts such as nickel on kieselguhr, Raney nickel, copper chromate, molybdenum sulfide and finely divided platinum or other noble metals on a low surface area carrier.
Hydrogenation may be ~onducted at any desired temperature or pressure, from atmospheric to 300 psig, the usual range being between 100 and 1,000 psig at temperatures from 75 F. to 600 F. for times betwQen 0.1 and 2~ hours, preferably from 0.2 to 8 hours.
Hydrogenated block copolymers such as Kraton~ G-6500, Kraton~ G-6521, Kratone G-1650 and Kraton~ &-1652 are available from Shell Chemical Company, Polymers Division. Kraton~ G-1550 and Kraton~ G-1651 are preferred for use in the compositions ofthe invention. Also usable are the so-called hydrogenated Solprenes of Phillips Petroleum Co., especially the product designated Solprene0-512.

,, .
,, :

The radial teleblock copolymers, of which the Solprenes are typical examples, ca~ be characterized as having at least three polymer bxanches with each branch of the radial block polymer comprising texminal non~elastomeric segments, e.g. ~A) and (Al ) as defined hereinaboveO The branches of the radial block polymer contain a terminal non-elastomeric segment attached to an elastomeric polymer segment, e.g. (B) as defined above. These are described by Marrs, U.S. Pat. No. 3,753,936 and by æelinski~ U.S.
Pat. No. 3,281,383, both o~ which are incorporated herein by refer2nce, and they are selectivPly hydrogenated by procedures as described above. In any event, the term "selective hydrogenation" is usPd herein to contemplate polymers in which the elastomeric blocks (B) have been hydrogenated, but the non-elastomeric blocks (A) and (A1) have been left unhydrogenated, i.e., aromatic.
The selectively hydrogenated copol~er is used in a proportion of from about 1 to 4 parts by weight (prefarably 2 parts by weight for each 100 parts of polycarbonate resin.
Preferred as the impact-modifier used in the compositions o~ the invention are the so-called "ABS" polymers. ABS polymers are defined, for example, in the Modern Plastics Encyclopedia, 19~9 edition, page 92, as the family of thermoplastics made from the three monvmers acrylonitrile, butadiene and styrene, and more speci~ically as a mixture (alloy) o~ ~tyrene-acrylonitrile copolymer with SAN-gra~ted polybutadiene rubber.
The preferred ABS polymer of high rubber content for use as an impact-modifier i5 an ABS having ' ' ' ' ' .

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greater than 32% rubber content and made by emulsion polymerization, rather than ~y bulk or suspension polymerization which are processes ~requently used to manufacture commercial ABS; an ABS made by 5 emulsion polymerization is U.S. Pat. 2,820,773 (1958) which is incorporated by reference. ABS
resins made by emulsion polymerization and having high rubber content are commercially available, for example the following:
Novalar made by ~ova Polymers, Inc.: a powdered ABS
having about 41% butadiene rubber content, a density of 1.04 and a melt flow index of 4.0; and Blendex 301 made by General Electric Company: a powdered ABS having about 34~ polybutadien rubber 15 content, a specific gravity of 0.99 by ASTM D-792 Method A-l, and a heat deflection temperature of 172 F at 10 mil deflection and 264 psi (annealed) by ASTM D-648.
Impact - modifying agents for use with the polycarbonate compositions of the invention also include the various polyacrylate resins known in the art. For example, suitable polyacrylates can be made in known ways, but are abundantly commercially available from many sources, e.g., Rohm & Haas Chemical Company, Philadelphia, Pa. under the trade designations Acryloid~ KM 330, and 7709 XP; Goodyear Tire & Rubber Company, Akron, Ohio under the trade designation RXL~ 6886; from American Cyanamid Company, Stamford, CT., ùnder the trade designation CyanacrylX 770; from M&T Chemicals Co., Trenton, NJ, under the trade designation Durostrength~ 200: and from Polysar Corporation, Canada, under the trade designation Polysar~ 100S. In general any of the :,. - . - . ~ . ~ ,, ' J j~ J ' polyalkyl acrylates described by Brinkman et al., U.S. Pat. No. 3,591,659 can be used, especially those containing units derived from n-butyl acrylate. Preferably, the polyacrylate will comprise a multiple stage polymer having a rubbery first stage and a thermoplastic hard final stage as described in Farnham et al., U.S. Pat. No. 4,096,202 incorporated herein by reference. It has also been found advantageous to add both polyalky acrylate and an acrylate-based core-shell polymer such as Acryloid~ KM-330, above-mentioned.
The polyacrylate resin impact modifiers may be added to the compositions of the invention in conventional amounts of from 0.01% to 50% by weight based on the weight of the overall composition and usually in amounts of from 0.01% to 10% by weight on the same basis.
Another class of known polycarbonate impact modifiers which may be used as an ingredient of the resin compositions of the invention are polyamide-polyether block copolymers which may be represented by the schematic formula: -~O O
HO- - ~ - PA - ~ - O - PE - O- - H
n (IX) wherein PA represents the polyamide segment, PE
represents a polyether segment and n is an integer such that the block copolymer has a weight average molecular weight (~) of from about 5,000 to about 100,000. Polyamide-polyether bloc~ copolymers of the class described above are generally well known and may be prepared for example by the condensation ., :-, ~ . :

,:

~ 3 reaction of a prepolyamide and a polyoxyalkylene glycol, by conventional technique; see for example the preparative methods described in U.S. Patents 4,20~,493; 4,230,838: 4,361,680: and 4,331,786, all of which are incorporated herein by reference thereto. The polyamide - polyether block copolymers so prepared are commercially available and may be wide ranging in their make-up from a wide range of prepolyamides and polyoxyalkyiene glycols.
The prepolyamide may have an inherent viscosity of at least about 0.1 (determined at a temperature of 25~C. using o.25 ~m of polymer per 100 ml. of a solvent consisting of 60 percent phenol and 40 percent by volume of tetrachloroethane) and will be terminated with acid or amine groups. The prepolyamide may be the polymerization product of a difunctional diamine component and a difunctional dicarboxylic acid.
In general, any aliphatic, alicyclic, and aromatic difunctional diamine or mixture ot diamines can be used to prepare the prepolyamide. Examples of such diamines include polymethylenediamines of the formula H2N (CH2~XNH2, wherein x is a positive integar of ~rom 2 to 12 (such as dimethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, and dodecamethylenediamine);
1,1-, 1,2-, 1,3-, and 1,4- cyclohexane-bis-(methylamines); o-, m-, and p-xylenediamines; l,2-, 1,3- and 1,4-cyclohexanediamines; 3-methylhexa-methylenediamine; 3-methylheptamethyenediamine;

`, , ~ ~ . '' ' . "' . ' ' ' - .

2,4-dimethylhexamethylenediamine;
2,4-toluenediamine; p,p'-diphenydiamine;
1,4-dimethyl 3,5-diaminobenezene;
2,5-norcamphane-bis-(methylamine); o-, m-, and p-phenylenediamines; 2,5-,2,6-, and 2,7-naphthalenediamines; benzidine;
4,4'-methylenedianiline; and 3,4'-diaminodiphenyl.
The N,N'-diphenyldiamines of U.S. Pat. 3,297,656 can also be employed.
In general, any aliphatic, alicyclic, and aromatic difunctional dicarboxylic acid can be used to prepare the prepolyamide. Examples of such acids include oxalic; malonic; dimethylmalonic; succinic;
glutaric; adipic; trimethyladipic; pimelic;
2,2-dimethylglutaric; azelaic; sebacic; suberic;
fumaric; maleic, itaconic;
1,3-cyclopentanedicarboxylic:
1,2-cyclohexanedicarboxylic;
1,3-cyclohexanedicarboxylic;
1,4-cyclohexanedicarboxylic; phthalic; terephthalic;
isophthalic; t-butyl isophthalic;
2,5-norbornanedicarboxylic~
1,4-naphthalenedicarboxylic; diphenic;
4,4'-oxydiben~oic; diglycolic; thiodipropionic;
2,2,4-trimethyladipic; 4,4'-sulfonyldibenzoic;
2,5 naphthalenedicarboxylic;
2,6-naphthalenedicarboxylic; and 2,7-naphthalenedicarboxylic acids.
The prepolyamides are prepared by conventional and known techniques for the preparation of a polyamide resin and may have a weight average molecular weight of from 300 to 15,000.

.
.

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The polyoxyalkylene glycols used to prepare the polyamidepolyether block copolymers used as impact-modifiers in the pre~ent invention are well known compounds and include for example polyoxypropylene glycol, polyoxyethylene glycol and polyoxybutylene glycol, each of which are commercially available and have weight average molecular weights (~) of from 200 to 15,000. The preferred polyoxyalkylene glycols may also be charactexized by an inherent viscosity of from 0.1 to 0.5 (determined a~ described above for the determination of inharent viscosity of the prepolyamide). The polyether can have diol and/or diamine end groups, amino end groups can be prepared through cyanoethylation of the polyether followed by hydrogenation. Other modifications of the polyether end groups can also be made to facilitate bonding to the polyamide blocks.
The preferred impact-modifying polyamide-polyether block copolymer employed in the compositions and the method of the invention are of the formula (IX) given above, wherein PA represen~s a saturated amide sequence formed from a lactam or an amino acid having a hydrocarbon chain containing from 4 to 14 carbon atoms, inclusive, or from a diamine and a dicarboxylic acide each having from 4 to 40 carbon atoms, inclusive; said amide having a weight average molecular weight of from 300 to 15,000; and PE represents a polyether sequence formed from a polyoxyalkylene glycol having a weight of ~rom 200 to 15,000. Most preferred, the copolymer will be one wherein the proportion by weight of polyoxyalkylene glycol with respect to the total . . , ~

weight of the copolymer is from 5 to 85 percent. In general, these preferred block copolymers will have an intrinsic viscosity of from 0.8 to 2.05 as measured in meta-cresol at 25 C. (initial concentration: 0.8 gms/100 ml).
The polyamide-polyether impact-modifying copolymer can be present in a wide range of concentrations. However, to obtain the most useful blends, it is preferable to maintain the concentration of impact-modifying copolymer to less than 40% by weight of the total composition of the invention. Concentrations of from 2 to 30 weight percent of impact-modifying copolymer provide a significant enhancement in impact strength without a significant enhancement in impact strength without a significant loss to other desirable physical properties of the blend, such as heat distortion temperature. Concentrations bPlow 5% by weight can be expected tohave an enhancing ~ffect on impact strength but atlevels which correspond to the low concentration. The most preferred concentrations fall within the highest impact modifying e~ect varying with the ratio of polycarbonate to polyamide, as discuss~d above.
Other representative impact modifiers are the synthetic polymeric resin elastomers such as silicone rubber, polyether rubber and ethylene-propylene-diene rubber; diene rubbers, i.e., homopolymers of conjugated dienes having, e.g. 4 to 8 carbon atoms, such as butadiene, isoprene, norbornene, piperylene and chloroprene: and copolymers of dienes such as ethylene with each other or with styrene, acrylic acid, methacrylic , :
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acid, or derivatives thereof (e.g., acrylonitrile, methacrylo-nitrile, acrylic acid, methacrylic acid, butyl acrylate and methyl methacrylate), or isobutylene.
An impact-modifying proportion of the latter impact modifers described above is generally within the range of from about 0.05 to 15 parts by weight of the composition, preferably from 3-10 parts, most preferably 4 to 8 parts.
Other impact-modifying agents useful in the compositions of the invention will be appreciated by those skilled in the art.
It will be appreciated by those skilled in the art that an impact modifying proportion of the lS impact modifier used in the compositions of the invention will be dependent upon the particular modifier selected. In general however, the proportion will be most preferably one within the range of from about 5 to about 20 parts by weight of the polycarbonate.
The compositions of the invention may be prepared by homogeneously blending with the polycarbonate the copolymer of the styrene-acrylonitrile and the impact modifier described above. The blending may be carried out by use of conventional and known techniques and apparatus for the blending together of synthetic polymeric resin components. In general, the mixtures of components may be blanded by pre-mixing in conventional mixing rolls, dough mixers, Banbury mixers and the like and by blending the pre-mix in an extruder or fluxing it on a mill at an elevated temperature sufficient to achieve a homogeneous blending. Upon cooling, the -- , , : : .

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blend may be palletized and stored for molding into articles.
The thermoplastic blend o~ the invention may also be compounded with conventional ~olding aids such as, for example, antioxidant~; antistatic agents; inert fillers such as glass, talc, mica, and clay; ultraviolet radiation absorbers such as the benzophenones, benzotriazoles, and the like:
hydrolytic stabilizers such as the epoxides disclosed in U.S. Pats. Nos. 3,489,716, 4,138,379 and 3,839,247, all of which are incorporated herein by reference: color stabilizers such as the organophosphites; thermal stabilizers such as phosphite; mold release agents and ~lame retardants.
Some particularly useful flame retardants are the alkali and alkaline earth metal salts of sulfonic acids. TheRe type~ of flame retardants are disclosed in U.S. Pats. Nos. 3,933,734; 3,931,100;
3,978,~24; 3,948,851; 3,926,980; 3,919,167;
3,909,490; 3,953,396; 3~953/300; 3,917,559;
3,951,910 and 3,940,366, all o~ which are hereby incoxporated herein by reference.
The following examples describe the manner and proce~s of making and using the invention and set forth the ~est mode contemplated by ths inventor ~or carrying out the invention but are not to be construed as limiting the scop~ of the invention.
All parts are by w~ightO Test results are in accordance with the following test m~thode.
Inkrinsic Viscosity:
The intrinsic YisCOsity O~ polycarbonates was measured at a temperature of 25C in methyl~ne chloride and i8 reported in deciliters/gram (de/g).

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Tensile Stren~ths and Elonqation ASTM Test Method D-638.
Flexural Yield and Modulus ASTM Test Method D-790.
Notched Izod Impact Strength:
ASTM Test Method D~256; all specimens were 100%
ductile at failure, unless otherwise noted.
Melt Flow:
ASTM Test Method D-1232.
Weld Line Strenath:
ASTM Test ~ethod D-256.
R*:
R* may be calculated as follows:
STEP 1 - Generate viscosity (~*) and elastic modulus (G') data on test compositions at three temperatures, with a rotational rheometer such as the RDS 7000, (Rheometrics Inc.).
STEP 2 - Using the data from STEP 1 fitted to the Arrhenius type equations, calculate optimum melt temperature for parison extrusion (i.e., the temperature required to yield a melt viscosity of 20,000 poise at 100 sec~l).
STEP 3 - Calculate the ratio of viscosity at low shear rate (1 sec 1 nominal) to viscosity at 100 sec 1 (20,000 polse), R*, at temperature estimatad in STEP 2. Elastic modulus ~alues (@ 1 sec 1) are also calculated at this temperature.
Exa~ple 1:
Sixty-five parts by weight of a branched poly-carbonate prepared according to the method described in U.S. Patent No. 4,101,184 and having an intrinsic viscosity of from about 0.5 to about 0.65 deciliters/gram dl/g) as determined in a methylene chloride solution at a temperature o~ 25 C (LEXAN9 , . -:

' : ' ' 155, General Electric Co.) is mixed with 25 parts of Blendex~ 580 SAN, General Electric Co., (a SAN
copolymer of styrene and acrylonitrile with a SAN
ratio of ~2:28) and 10 parts of Blendex~ 338, Gen~ral Electric Co., supra. (a powdered ABS, made by emulsion polymerization). The mixture is uniformly blended together in a laboratory tumbler and the blend then introduced into a melt extruder.
The extrudate is pelletized and the pellets are fed to an injection molding machine to mold test ~ars of 5.715 cm x 1.27cnwith a thickness of 3.175mm. The moldings are subjected to tests to determine their blow-moldability and physical properties. The test results are given in the Table, below.
Examples a- 4:
The procedure of Example 1, supra., is repeated except that the proportions of the ingredients are modified. The proportions of ingredients and test results are given in the Table below.
Example 5 (Comparative Example!
The procedure of Exam~les 2-4, supra. is repeated except that the weight proportion of ABS
resin as used therein is replaced by an equal proportion of additional Lexan ~ 155 polycarbonate resin. The test results are shown in the Table, below.
All af the resin compositions prepared in accordance with the Examples 1-4, supra., are readily blow molded into articles such as bottles and automotive parts having large dimensions and exhibiting the same physical properties assigned to the resin compositions from which they are molded.

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As can be seen from the Table above, the compositions of the invention produce molded articles useful where impact-resistance is required and have processing properties useful in blow-molding technique, particularly where articles of relatively large size (circa 4-20 Kg) are molded.

,

Claims (11)

1. A thermoplastic, blow-molding resin compomition of improved processability, which comprises;
a blow-moldable branched polycarbonate resin;
a processability enhancing proportion of a thermoplastic copolymer of a styrenic monomer with an acrylonitrile monomer; and an impact modifying proportion of a polycarbonate impact modifier.

2. The composition of claim 1 wherein the styrene-acrylonitrile copolymer has from 20 to 35 percent acrylonitrile segments.

3. The composition of claim 1 wherein the styrene-acrylonitrile copolymer has from 23 to 32 percent of acrylonitrile segments.

4. The composition of claim 1 wherein the enhancing proportion is within the range of from about 5 to 30 parts by weight of the composition.

5. The composition of claim 1 wherein the styrenic monomer is a compound of the formula:

wherein each X is independently selected from the group consisting of hydrogen or alkyl of from 1 to 5 carbon atoms, inclusive; and the acrylonitrile monomer is of the formula:

wherein X is as defined above.

6. The composition of claim 5 wherein the thermoplastic copolymer is styrene-acrylonitrile.

7. The composition of claim 1 wherein said impact modifier is a selectively hydrogenated block copolymer resin of the A-B-A'; A(B-A-B)nA; A(B-A)nB;
or B[(A-Bn)B]4 type wherein n is an integer of from 1 to 10, inclusive; (A) and (A') are selected from styrene, alphamethylstyrene, p-methylstyrene, vinyl toluene vinyl xylene, and vinyl naphthalene and (B) is selected from butadiene, isoprene, 1,3-pentadiene and 2,3-dimethylbutadiene residues.

8. The composition of claim 1 wherein the impact modifier is an ABS copolymer.

9. The composition of claim 1 wherein the impact modifier is an ABS copolymer having at least 34% rubber content and made by emulsion polymerization.

10. An article molded from the composition of claim 1.

11. The invention as defined in any of the preceding claims including any further features of novelty disclosed.