MXPA97001810A - Polycarbonate mixtures and ethyl polymer - Google Patents

Abstract

The present invention relates to: A mixture of polycarbonate and a substantially linear ethylene polymer having a desirable balance of impact and solvency properties

Description

POLYCARBONATE MIXTURES AND ETHYLENE POLYMERS This invention relates to compositions containing polycarbonate and a substantially linear ethylene polymer. Polycarbonate has found many uses because, in general, it combines a high level of heat resistance and dimensional stability with good insulating and non-corrosive properties, and is easily molded. However, it suffers from a tendency to scratch and crack under the effects of contact with organic solvents such as gasoline. An undesirable result in the polycarbonate that has been scratched is that it is more likely to experience brittle failure instead of ductility. This drawback has been alleviated somewhat by the practice of mixing polycarbonate with different olefin polymers, such as low density polyethylene or linear low density polyethylene, or thermoplastic rubbers such as ethylene / propylene copolymer. These added substances are able to improve the strength of the polycarbonate to the solvents, but tend to delaminate and cause a reduction in hardness, impact strength, and strength of the bonding line of the mixed polycarbonate composition. This delamination, and the resulting loss of utility, is reported, for example, in U.S. Patent Number 4,496,693. Impact resistance in polycarbonate can be improved by the incorporation of emulsion or core-shell elastomers, such as methacrylate / butadiene / styrene copolymer, or a butyl acrylate rubber. However, these core-cover rubbers prevent the processability of the mixture by increasing the viscosity, and do not impart improvement to the solvent resistance of the polycarbonate. In accordance with the above, it would be desirable for modifiers to be mixed with the polycarbonate for the purpose of improving their resistance to the solvent and that they will not detrimentally affect their hardness and resistance to impact and the bonding line, nor will they cause delamination, as evidenced by separation or fragmentation in a molded article. In one aspect, accordingly, this invention involves a composition of matter containing, in admixture, polycarbonate and a substantially linear ethylene polymer. In another aspect, this invention involves the inclusion of this composition of a styrenic copolymer, a complementary impact modifier, and / or an additional molding polymer. It has been found that articles molded from the compositions of this invention show no tendency towards delamination, and exhibit a desirable balance of surprisingly high levels of impact resistance, solvent resistance, and processability. The compositions of this invention are useful, for example, in the production of films, fibers, extruded sheets, laminates in multiple layers, and molded or shaped articles of virtually all varieties, especially data storage devices, housings for apparatus and instruments. , motor vehicle body boards, and other parts and components for use in the automotive, electrical, and electronic industries. The compositions of this invention are those wherein: (a) polycarbonate has been mixed in a polymer blend, with (b) a substantially linear ethylene polymer. The compositions of this invention may also optionally contain: (c) a styrenic copolymer, (d) a complementary impact modifier, and (e) one or more additional molding polymers. The appropriate ranges of content for components (a) and (b) in the compositions of this invention, and the appropriate ranges of contents for components (c), (d), and (e), if and when they are present, expressed in parts by weight of the total composition, are as follows: (a) polycarbonate, at least about 60 parts, conveniently at least about 70 parts, and preferably at least about 80 parts, and yet not more than about 99 parts, conveniently no more than about 98 parts, and preferably no more than about 95 parts; (b) substantially linear ethylene polymer, at least about one part, conveniently at least about two parts, and preferably at least about 5 parts, and yet not more than about 40 parts, conveniently not more than about 30 parts, and preferably not more than about 20 parts; (c) styrenic copolymer, at least about 5 parts, conveniently at least about 10 parts, preferably at least about 15 parts, and more preferably at least about 20 parts, and yet not more than about 75 parts, conveniently no more of about 55 parts, preferably not more than about 50 parts, and more preferably not more than about 45 parts, - (d) complementary impact modifier, at least about 0.1 parts, conveniently at least about 0.5 parts, preferably at least about 1 part, and more preferably at least about 3 parts, and yet not more than about 25 parts, conveniently not more than about 20 parts, preferably not more than about 15 parts, and more preferably not more than about 10 parts; and (e) molding polymer, at least about 5 parts, conveniently at least about 10 parts, preferably at least about 15 parts, and more preferably at least about 20 parts, and yet not more than about 75 parts, conveniently no more than about 55 parts, preferably no more than about 50 parts, and more preferably no more than about 45 parts. The number of parts by weight of the different components from which the compositions of this invention can be prepared can be, but is not necessary, a total of up to 100 parts by weight. Within this invention, the reaction products, if any, of the aforementioned components, mixed in the compositions of this invention are also included. The preparation of the compositions of this invention can be carried out by any suitable mixing element known in the art. When softened or melted by the application of heat, the compositions of this invention are useful for manufacture, and can be formed or molded using conventional techniques. The component (a) in the compositions of this invention is a polycarbonate, which can be prepared from a dihydroxy compound, such as bisphenol, and a carbonate precursor, such as a disubstituted carbonic acid derivative, a haloformate ( such as a bishaloformate of a glycol or dihydroxybenzene), or a carbonate ester, such as diphenyl carbonate, or a substituted derivative thereof. These components are often reacted by means of the phase limit process, wherein the dihydroxy compound is dissolved and deprotonated in an aqueous alkaline solution, to form bisphenolate, and the carbonate precursor is dissolved in an organic solvent. The aqueous alkaline solution often has a pH higher than 8.0 or 9.0, and can be formed in water from caustic soda, such as NaOH, or from other bases such as those included in phosphates, bicarbonates, oxides, and hydroxides of alkali metal and alkaline earth metal. The base is typically used in an amount of about 2 to 4, preferably about 3 to 4 moles per mole of dihydroxy compound. These components are often reacted by means of a mixture initially prepared from the aromatic dihydroxy compound, water, and a non-reactive organic solvent immiscible with water selected from those wherein the carbonate precursor and the carbonate product are soluble. . Representative solvents include chlorinated hydrocarbons, such as methylene chloride, 1,2-dichloroethane, tetrachloroethane, chlorobenzene, and chloroform. Then caustic soda or other base is added to the reaction mixture to adjust the pH of the mixture to a level at which the dihydroxy compound is activated to a dianionic form. A carbonate precursor is contacted with a stirred mixture of the aqueous alkaline solution of the dihydroxy compound, and for that purpose, the carbonate precursor can be bubbled into the reaction mixture in the form of a gas, or can be Dissolve and introduce in solution form The carbonate precursor is typically used in an amount of about 1.0 to 1.8, preferably about 1.2 to 1.5 moles per mole of dihydroxy compound The mixture is stirred in a manner that is sufficient to dispersing or suspending droplets of the solvent containing the carbonate precursor in the aqueous alkaline solution The reaction between the organic and aqueous phases created by this stirring produces the bis (carbonate precursor) ester of the dihydroxy compound. The carbonate precursor is a carbonyl halide, such as phosgene, the products of this initial phase of the process are monomers or oligomers, which are either mono- or d i-chloroformates, or contain a phenolate ion in each term. These intermediate mono- and oligo-carbonates are dissolved in the organic solvent as they are formed, or they can then be condensed to a higher molecular weight polycarbonate by contact with a coupling catalyst, such as a tertiary amine.

This catalyst can be added to the reaction mixture before or after a dihydroxy compound is contacted with a carbonate precursor, and is typically used in an amount of about 0.01 to 0.1 moles per mole of dihydroxy compound. The polycarbonate forming reaction can be run at a pH from more than 7.0 to about 14, and at a temperature between 0 ° C and 100 ° C, although usually not higher than the boiling point (reflux temperature) of the solvent used. Frequently, the reaction is run at a temperature of about 0 ° C to about 45 ° C.

Upon completion of the polymerization, the organic and aqueous phases are separated to allow washing and purification of the organic phase and recovery of the polycarbonate product by devolatilization or precipitation. Examples of some suitable dihydroxy compounds for the preparation of polycarbonate include differently bridged, substituted, or unsubstituted aromatic dihydroxy compounds (or mixtures thereof), represented by the formula: wherein: (I) Z is (A) a divalent radical, of which all or different portions may be (i) linear, branched, cyclic, or bicyclic, (ii) aliphatic or aromatic, and / or (iii) saturated or unsaturated, this bivalent radical being composed of 1 to 35 carbon atoms, together with up to 5 oxygen, nitrogen, sulfur, phosphorus, and / or halogen atoms (such as fluorine, chlorine, and / or bromine); or (B) S, S2, SO, S02, O or CO; or (C) a single link; (II) each X is independently hydrogen, a halogen (such as fluorine, chlorine, and / or bromine), an alkyl, aryl, alkaryl, aralkyl, alkoxy, or linear or cyclic aryloxy radical, of 1 to 12 carbon atoms , preferably from 1 to 8 carbon atoms, such as methyl, lime, isopropyl, cyclopentyl, cyclohexyl, methoxy, ethoxy, benzyl, tolyl, xylyl, phenoxy, and / or xyloxy; or a nitro or nitrile radical; and (III) m is 0 or 1.

For example, the bridging radical represented by Z in the above formula can be an alkyl radical of 1 to 30 carbon atoms, cycloalkyl, alkylidene, or cycloalkylidene, or two or more thereof connected by an aromatic or ether, or it may be a carbon atom with which one or more groups such as CH, C2H5, C3H7, n-C3H7, i-C3H7, cyclohexyl, bicyclo [2.2.1] heptyl, benzyl, CF2, CF3, CC13, CF2C1, CN, (CH2) 2COOCH3, or PO (OCH3). Representative examples of the dihydroxy compounds of particular interest are the bis (hydroxyphenyl) alkanes, the bis (hydroxyphenyl) cycloalkanes, the dihydroxydiphenyls, and the bis (hydroxyphenyl) sulfones, and in particular are 2, 2-bis (4- hydroxyphenyl) propane ("bisphenol A" or "Bis-A"); 2, 2-bis (3,5-dihalo-4-hydroxyphenyl) propane ("Tetrahalo-Bisphenol-A"), wherein the halogen can be fluorine, chlorine, bromine, or iodine, for example 2, 2-bis ( 3, 5-dibromo-4-hydroxyphenyl) propane ("Tetrabromo-Bisphenol-A" or "TBBA"); 2, 2-bis (3, 5-dialkyl-4-hydroxyphenyl) propane ("Tetraalkyl-Bisphenol-A"), wherein the alkyl can be methyl or ethyl, for example 2, 2-bis (3,5-dialkyl) -4-hydroxyphenyl) propane ("Te ramethyl-Bisphenol -A"); 1, 1-bis (4-hydroxyphenyl) -1-phenylethane ("Bisphenol-AP" or BIS-AP "); bishydroxyphenyl-fluorene; and 1,1-bis (4-hydroxyphenyl) cyclohexane, employing a process as described in general above, a polycarbonate product having a weight average molecular weight, determined by light scattering or gel permeation chromatography, of 8,000 to 200,000, and preferably 15,000 to 40,000, and / or a melt value can be obtained from about 3 to 150, preferably from about 10 to 80 (determined by ASTM Designation 1238-89, Condition 300 / 1.2), although values outside these ranges are also allowed.Molecular weight can be controlled by addition or mixing of reaction, of a chain terminator, which can be selected from monofunctional substances, such as phenols, alcohols, amines, imides, carbonic acid chlorides, sulfonic acid chlorides, benzyltriethylammonium chloride, or phenylchlorocarbonates. A chain terminator may be added to the reaction mixture before or after a dihydroxy compound is contacted with a carbonate precursor, and is typically used in an amount of about 0.01 to 0.1 moles per mole of dihydroxy compound . A branched, rather than linear, polycarbonate molecule can be obtained by adding a tri- or polyfunctional monomer, such as trimellitic acid, or trisphenoxyethane to the reaction mixture. Also included within the term "polycarbonate", as used herein, are different copolycarbonates, which can be prepared by incorporating two or more different dihydroxy compounds into the reaction mixture.; or a poly (ester / carbonate), which can be prepared by incorporating an ester-forming compound, such as terephthalic acid, into the reaction mixture. However, in a preferred embodiment, the compositions of this invention exclude a poly (ester / carbonate). The methods generally described above for the preparation of carbonate polymers suitable for use in the practice of this invention are well known; for example, several methods are discussed in detail in Schnell, U.S. Patent No. USP 3,028,365; Glass, Patent of the United States of America USP number 4,529,791; and Grigo, United States Patent Number USP 4,677,162, each of which is incorporated as a part hereof. Component (b) in the compositions of this invention is a substantially linear ethylene polymer, or a mixture of more than one thereof. These substantially linear ethylene polymers are known, and they and their method of preparation are fully described in U.S. Patent Nos. USP 5,272,236 and USP 5,278,272, both of which are incorporated herein by reference. As used herein, "substantially linear" means that the base structure of the polymer is substituted with about 0.01 long chain branches / 1000 carbon atoms to about 3 long chain branches / 1000 carbon atoms, preferably about 0.01 long chain branches / 1000 carbon atoms to about one long chain branch / 1000 carbon atoms, more preferably about 0.05 long chain branches / 1000 carbon atoms to about 1 long chain branch / 1000 carbon atoms. The long chain branching is defined herein as a chain length of at least about 6 carbon atoms, above which, the length can not be distinguished using 13C nuclear magnetic resonance spectroscopy, and nevertheless, the branching of Long chain can be about the same length as the length of the polymer base structure. These substantially linear ethylene polymers are prepared by the use of catalysts of limited geometry, and are characterized by a narrow molecular weight distribution, and if it is an interpolymer, by a narrow comonomer distribution. As used herein, "interpolymer" means a polymer of two or more comonomers, for example a copolymer or terpolymer, such as could be prepared by the polymerization of ethylene with at least one other comonomer. Other basic characteristics of these substantially linear ethylene polymers include a low residue content (i.e., a low concentration therein of the catalyst used to prepare the polymer, unreacted comonomers, and low molecular weight oligomers made during the course of the polymerization), and a controlled molecular architecture that provides good processability, even when the molecular weight distribution is narrow in relation to conventional olefin polymers. Although the substantially linear ethylene polymers used in the practice of this invention include substantially linear ethylene homopolymers, preferably substantially linear ethylene polymers comprise between about 50 and 95 weight percent ethylene, and about 5 al 50, preferably 10 to 25 weight percent of at least one alpha-olefin comonomer. The comonomer content is measured using infrared spectroscopy according to ASTM D-2238, Method B. Typically, substantially linear ethylene polymers are copolymers of ethylene and one or more alpha-olefins of 3 to about 20 carbon atoms (e.g., propylene, l-butene, 1-hexene, 4-methyl-l-pentene, 1-heptene, 1-octene, and / or styrene), preferably alpha-olefins of 3 to about 10 carbon atoms, and more preferably These polymers are a copolymer of ethylene and 1-octene. The density of these substantially linear ethylene polymers is typically between about 0.850 and about 0.935 grams per cubic centimeter (g / cm3), preferably from about 0.860 to about 0.900 grams / cm3. Its melt flow rate, measured as I10 / I2, is greater than or equal to 5.63, preferably it is from about 6.5 to 15, and more preferably is from about 7 to 10. The I2 ASTM is measured in accordance with ASTM Designation D 1238, Condition 190 / 2.16, and I10 according to condition 190 / 10.0. Their molecular weight distribution [weight average molecular weight divided by number average molecular weight (Mw / Mn)], measured by gel permeation chromatography (GPC), is defined by the equation: Mw / Mn <; (I10 / I2) of up to 4.63, and preferably between about 1.5 and 2.5. For substantially linear ethylene polymers, the I10 / I2 ratio indicates the degree of long chain branching, i.e., the higher the l10 / l2 ratio, the more long chain branching there is in the polymer. According to Ramamurthy in 30 (2) Journal of Rheology 337-357 (1986), a superficial melt fracture of the polymer may occur above a certain critical flow velocity, which may result in irregularities, from loss of specular brightness to the most severe form of "shark skin". As used herein, the setting of the surface melt fracture is characterized as the principle of extrudate gloss loss where the surface roughness of the extrudate can only be detected by a 40x amplification. The substantially linear ethylene polymers of the present are further characterized by a critical tear rate at the setting of the surface melt fracture that is at least 50 percent greater than the tear rate critical to the setting of the surface melt fracture. a linear olefin polymer having approximately the same I2 and Mw / Mn. The unique characteristic of these substantially linear, homogeneously branched ethylene polymers is a highly unexpected flow property, wherein the I10 / I2 value of the polymer is essentially independent of the polydispersity index (Mw / Mn) of the polymer. This is in contrast to homogeneously branched and linear heterogeneously branched linear polyethylene resins having conventional rheological properties such that, in order to increase the I10 / I2 value, the polydispersity index must also be increased. The preferred I2 melt index for these substantially linear ethylene polymers is from about 0.01 grams / 10 minutes to about 100 grams / minutes, and more preferably from about 0.1 to 10 grams / 10 minutes. Typically, these polymers are homogeneously branched, and do not have a measurable high density fraction, i.e., short chain branching distribution measured by Elution Fractionation with Temperature Raise which is described in US Pat. No. US Pat. 5,089,321 (incorporated herein by reference in its entirety). Stated another way, these polymers do not contain a polymer fraction having a degree of branching less than, or equal to, two methyl groups / 1000 carbon atoms. These substantially linear ethylene polymers are also characterized by a single melting peak by differential scanning calorimetry (DSC). Component (c) in the compositions of this invention is a styrenic copolymer prepared from one or more styrenic monomers, and one or more ethylenically unsaturated monomers copolymerizable with a carbon, cycloalkyl, alkenyl, cycloalkenyl, aryl, alkaryl monomer , aralkyl, or alkoxy; a halogen atom such as chlorine or bromine; or two E can be joined to form a naphthalene structure. Representative examples of suitable styrenic monomers, in addition to styrene itself, include one or more of the following: ring-substituted alkyl styrenes; Haloestyrenes substituted by ring; ring alkyl, styrenes substituted by ring halogen; and vinylnaphthalene or anthracene. The ethylenically unsaturated monomers of particular interest for copolymerization with a styrenic monomer include one or more of those described by the formula: D-CH == C (D) - (CH 2) n -G, wherein each D represents independently selected from the group consisting of hydrogen, halogen (such as fluorine, chlorine, or bromine), alkyl of 1 to 6 carbon atoms or alkoxy, or taken together represent an anhydride bond; G is hydrogen, vinyl, alkyl of 1 to 12 carbon atoms, cycloalkyl, alkenyl, cycloalkenyl, alkaryl, arylalkyl, alkoxy, aryloxy, ketoxy, halogen (such as fluorine, chlorine, or bromine), cyano, or pyridyl; and n is from 0 to 9. Representative examples of ethylenically unsaturated monomers copolymerizable with a styrenic monomer are those that carry a polar or electronegative group, and include one or more of the following: a styrenic. The styrenic copolymer can be a random, alternating, block, or grafted copolymer, and a mixture of more than one styrenic copolymer can also be used. Styrenic monomers of particular interest for use in the preparation of a styrenic copolymer, in addition to styrene itself, include one or more of the substituted styrenes or vinyl aromatic compounds described by the following formula [it being understood that a reference to "styrene" as a comonomer in component (c), it should be read as a reference to any of the styrenic or vinyl aromatic monomers described herein, or any others of a similar kind]: wherein each A is independently hydrogen, an alkyl radical of 1 to 6 carbon atoms, or a halogen atom, such as chlorine and bromine; and each E is independently hydrogen, an alkyl radical of 1 to 10 vinylnitrile compound; a diene; an alkylene compound of 2 to 10 carbon atoms, including halogen-substituted derivatives thereof, - alpha, beta-ethylenically unsaturated carboxylic acids and their anhydrides, and alkyl esters and amides of 1 to 10 carbon atoms, aminoalkyl, and hydroxyalkyl; an aliphatic or aromatic maleimide, - vinyl ketones, - vinyl or allyl acetate, and higher alkyl or arylvinyl or allyl esters, - vinyl alcohols; vinyl ethers and their derivatives substituted by alkyl or halogen; and an oxazoline compound. Examples of the preferred styrenic copolymers are aromatic vinyl / vinyl nitrile copolymers, such as styrene / acrylonitrile copolymer ("SAN"), styrene / maleic anhydride copolymer, styrene / glycidyl methacrylate copolymer, aryl maleimide / vinyl nitrile copolymer / diene / styrenic, styrene / alkyl methacrylate copolymer, styrene / alkyl methacrylate / glycidyl methacrylate copolymer, styrene / butyl acrylate copolymer, methyl methacrylate / acrylonitrile / butadiene / styrene copolymer, or an aromatic vinyl copolymer / rubber modified vinylnitrile, such as an ABS, AES, or ASA copolymer. ABS (acrylonitrile / butadiene / -styrene copolymer) is an elastomeric-thermoplastic compound wherein the aromatic vinyl / vinylnitrile copolymer is grafted onto a polybutadiene substrate latex. The polybutadiene forms rubber particles - the rubber modifier or the elastomeric component - which are dispersed as a separate phase in a thermoplastic matrix formed by the random vinyl aromatic / vinylnitrile copolymer. Typically, the vinyl aromatic / vinyl nitrile copolymer becomes clogged as much as it is grafted onto the rubber particles. AES (acrylonitrile / EPDM / styrene copolymer) is a styrenic copolymer obtained when the vinyl aromatic / vinylnitrile copolymer is modified with rubber by grafting vinyl aromatic / vinylnitrile copolymer onto a substrate made of an EPDM rubber ( ethylene / propylene / non-conjugated diene). An aromatic vinyl / vinyl nitrile copolymer can also be crosslinked in an alkyl acrylate elastomer to form a rubber modified styrenic copolymer, as in the case of an ASA (acrylonitrile / styrene / acrylate) copolymer. A styrenic copolymer can be made by an emulsion, suspension, or bulk (by volume) method. Component (d) in the compositions of this invention is a complementary impact modifier, including, for example, elastomers, such as a block copolymer, a core-shell graft copolymer, or mixtures thereof. A block copolymer useful as a complementary impact modifier herein may be linear, branched, radial, or teleblock, and may be a diblock copolymer ("AB"), a triblock copolymer ("ABA") , or a radial teleblock copolymer with or without thinned sections, ie, portions of the polymer wherein the monomers alternate or are in a random order near the transition point between blocks A and B. Portion A is often prepared by polymerizing one or more vinyl aromatic hydrocarbon monomers, such as the different styrenic monomers described above with respect to a styrenic copolymer; it has a weight average molecular weight of about 4,000 to about 115,000; and has . characteristic properties of thermoplastic substances, because it has the necessary stability to process at high temperatures, and yet, have a good resistance below the temperature at which it softens. B portion of the block copolymer typically results from polymerizing substituted or unsubstituted 3 to 10 carbon atoms, particularly conjugated dienes such as butadiene or isoprene; it has a weight average molecular weight of from about 20,000 to about 450,000; and is characterized by elastomeric properties that allow it to absorb and dissipate an applied tension, and then regain its shape.

To reduce oxidation and thermal instability, the block copolymers used herein may also be desirably hydrogenated to reduce the degree of unsaturation on the polymer chain and on the pendant aromatic rings. The most preferred aromatic vinyl block copolymers are the vinyl aromatic / conjugated diene block copolymers formed from styrene and butadiene, or styrene and isoprene. When the styrene / butadiene copolymers are hydrogenated, they are often represented as a styrene / (ethylene / butylene) copolymer in the diblock form, or as a styrene / (ethylene / butylene) / styrene copolymer in the triblock form. When the styrene / isoprene copolymers are hydrogenated, they are often represented as a styrene / (ethylene / propylene) copolymer in the diblock form, or as a styrene / (ethylene / propylene) / styrene copolymer in the triblock form. The aromatic vinyl block / diene copolymers as described above are commercially available as the different Kraton ™ elastomers from Shell Chemical Company. The core-shell graft copolymer elastomers suitable for use herein as a complementary impact modifier, are those that are based either on a diene rubber, an alkyl acrylate rubber, or mixtures thereof, and have an elastomeric or rubber phase that is greater than about 45 percent or more of the copolymer by weight. A core-shell graft copolymer based on a diene rubber contains a substrate latex, or core, which is made by the polymerization of a diene, preferably a conjugated diene, or by the copolymerization of a diene with a mono- olefin or a polar vinyl compound, such as styrene, acrylonitrile, or an alkyl ester of an unsaturated carboxylic acid such as methyl methacrylate. A mixture of ethylenically unsaturated monomers in the substrate latex is then polymerized by grafting. A variety of monomers can be used for this grafting purpose, of which the following are examples: vinyl aromatics; vinylnitriles, - an alkyl acrylate or methacrylate of 1 to 8 carbon atoms, - glycidyl methacrylate; acrylic or methacrylic acid; and the like, or a mixture of two or more thereof. Preferred graft monomers include one or more of styrene, acrylonitrile, and methyl methacrylate. A core-shell graft copolymer based on an alkyl acrylate rubber has a first phase that forms an elastomeric core, and a second phase that forms a rigid thermoplastic phase around the elastomeric core. The elastomeric core is formed by emulsion or suspension polymerization of monomers which consist of at least about 50 weight percent alkyl and / or aralkyl acrylates, having up to 15 carbon atoms, and although more chains may be used long, the alkyl groups are preferably 2 to 6 carbon atoms, more preferably butyl acrylate. The rigid thermoplastic phase of the acrylate rubber is formed on the surface of the elastomeric core, using suspension or emulsion polymerization techniques. The monomers necessary to create this phase include ethylenically unsaturated monomers, such as glycidyl methacrylate, or an alkyl ester of an unsaturated carboxylic acid, for example, an alkyl acrylate or methacrylate of 1 to 8 carbon atoms, such as methyl methacrylate. , or mixtures of any of the foregoing. Other complementary impact modifiers or elastomers useful in the compositions of this invention are those generally based on a long chain hydrocarbon base structure ("olefinic elastomers"), which can be prepared predominantly from different monomers of mono- or di-alkenyl, and can be grafted with one or more styrenic monomers. Representative examples of a few olefinic elastomers that illustrate the variation in known substances that would be sufficient for this purpose are as follows: butyl rubber, - chlorinated polyethylene rubber; chlorosulfonated polyethylene rubber, - an olefin polymer or copolymer, such as ethylene / propylene copolymer, ethylene / styrene copolymer, or ethylene / propylene / diene copolymer, which can be grafted with one or more styrenic monomers; neoprene rubber, - nitrile rubber; polybutadiene, and polyisoprene. An example of a preferred olefinic elastomer is a copolymer prepared from: (i) at least one olefin monomer, such as ethylene, propylene, isopropylene, butylene, or isobutylene, or at least one conjugated diene, such as butadiene and the like , or mixtures thereof; and (ii) an ethylenically unsaturated monomer carrying an epoxide group (e.g., glycidyl methacrylate), and optionally (iii) an ethylenically unsaturated monomer not bearing an epoxide group (e.g., vinyl acetate). The component (e) in the compositions of the invention is a molding polymer selected from: (i) polyester, (ti) other olefin-based polymers, and mixtures thereof. Component (e) (i), a polyester, as used in the compositions of this invention, can be made, for example, by the self-esterification of hydroxycarboxylic acids, or by direct esterification, which involves the reaction growing by Steps of a diol with a dicarboxylic acid, with the resulting elimination of water, giving a polyester with a repeating unit of - [-AABB-] -.

Reagents suitable for making the polyester used in this invention, in addition to the hydroxycarboxylic acids, are diols and dicarboxylic acids, either or both of which may be aliphatic or aromatic. Accordingly, a polyester which is a poly (alkylene alkadicarboxylate), a poly (alkylene arylene dicarboxylate), a poly (to the aryl carboxylate), or a poly (arylene dicarboxylate) of the present invention is suitable for use herein. ethylene). The alkyl portions of the polymer chain may be substituted with, for example, halogens, alkoxy groups of 1 to 8 carbon atoms, or alkyl side chains of 1 to 8 carbon atoms, and may contain bivalent heteroaromatic groups (such as -OR-, -Si-, -S-, or -S02-) in the paraffinic segment of the chain. The chain may also contain unsaturation and non-aromatic rings of 6 to 10 carbon atoms. The aromatic rings may contain substituents such as halogens, alkoxy groups of 1 to 8 carbon atoms or alkyl of 1 to 8 carbon atoms, and may be attached to the base structure of the polymer at any position on the ring, and directly to alcohol or the functionality of acid, or the atoms that intervene. Typical aliphatic diols used in the ester formation are the primary and secondary glycols of 2 to 10 carbon atoms. The alkadicarboxylic acids frequently used are oxalic acid, adipic acid, and sebasic acid. The diols containing rings can be, for example, a 1,4-cyclohexylenyl glycol or a 1,4-cyclohexane-dimethylene glycol, resorcinol, or one of the many bisphenols such as 2,2-bis (4-hydroxyphenyl) propane. Aromatic diacids include, for example, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenylethericarboxylic acid, and diphenylsulfondicarboxylic acid. In addition to the polyesters formed from a diol and a diacid only, the term "polyester" as used herein, includes random copolyesters, in patterns, or block, for example, those formed from two or more different diols, and / or two or more different diacids, and / or from other bivalent heteroatomic groups. Mixtures of these copolyesters, blends of polyesters derived from a diol and a diacid only, and mixtures of members of both of these groups, are also all suitable for use in this invention, and are all included in the term " polyester ". Aromatic polyesters, those prepared from an aromatic diacid, such as the poly (alkylene arylene dicarboxylates), polyethylene terephthalate, and polybutylene terephthalate, or mixtures thereof, are particularly useful in this invention. Component (d) (ii) includes a variety of olefin-based polymers that are not part of the substantially linear ethylene polymer category described above as component (b). These other olefin-based polymers include conventional homogeneously branched or heterogeneously branched linear ethylene polymers, either of which may be grafted or non-grafted. Examples of these polymers include high density polyethylene, low density polyethylene, linear low density polyethylene, ultra low density polyethylene, polypropylene, polyisobutylene, ethylene / acrylic acid copolymer, ethylene / vinyl acetate copolymer, copolymer ethylene / vinyl alcohol, ethylene / carbon monoxide copolymer (including those described in U.S. Patent Nos. 4,916,208 and 4,929,673), ethylene / propylene / carbon monoxide copolymer, ethylene / carbon monoxide / acid copolymer acrylic, polystyrene, poly (vinyl chloride), and the like, and mixtures thereof. Conveniently a variety of additives may be employed to promote fire retardancy or ignition resistance in the compositions of this invention, or as antimicrobial agents; antioxidants; antistatic agents; fillers and reinforcing agents, - hydrolytic stabilizers, - lubricants, mold release agents; pigments, dyes, and colorants; plasticizers; heat stabilizers; stabilizers in ultraviolet light. A preferred hindered phenolic antioxidant is the antioxidant Irganox ™ 1076, available from Ciba-Geigy Corp. These additives, if used typically, do not exceed 45 weight percent of the total composition, and conveniently are from about 0.001 to 15 percent, preferably from about 0.01 to 10 percent, and more preferably from about 0.1 to 10 percent by weight of the total composition. To illustrate the practice of this invention, examples of several preferred embodiments are stipulated below; however, these examples (Examples 1 to 3) in no way restrict the scope of this invention. Some of the particularly desirable characteristics of this invention can be seen by contrasting the characteristics of Examples 1 to 3 with those of the different controlled formulations (Controls AH) that do not possess the characteristics of, and therefore are not modalities of, this invention. The compositions of Examples 1 to 3 and of the A-H controls are prepared by mixing the dry components in the paint agitator for 5 minutes, and then feeding the dry mixed formulation to a Werner & Pfleiderer of 30 millimeters established at a barrel zone temperature of 280 ° C, at 250 rpm, and with a torque of 70 to 85 percent. The extrudate is cooled in the form of strands, and then crushed as granules. The granules are dried in an air extraction oven for 3 hours at 120 ° C, and then used to prepare test samples in a 70 ton Arburg molding machine having positions in the temperature zone of 150 ° C, 200 ° C, 250 ° C, 250 ° C, and 250 ° C, and a mold temperature of 80 ° C. The content of the formulation of Example 1 and of Controls A-E is given below in Table I, in parts by weight of the total composition. In Table I: "Polycarbonate" is a polycarbonate of bisphenol-A, having a weight average molecular weight of 28,000; "LLDPE I" is a linear low density polyethylene having a melt index, according to ASTM D 1238, of 2; "LLDPE II" is a linear low density polyethylene having a melt index, according to ASTM D 1238, of 26; "EPR" is a copolymer of 45 weight percent ethylene and 55 weight percent propylene; "MBS" is methacrylate / styrene / -butadiene copolymer (Paraloid ™ 8963 from Rohm &Haas), - and "ITP" is a substantially linear ethylene polymer, as described above as component (b), having a density of approximately 0.87 grams per cubic centimeter. The following tests are performed on Example 1 and Controls A-E, and the results of these tests are also shown in Table I: Impact resistance is measured by the test Izod ("Izod") according to ASTM Designation D 256-84 (Method A) at -35 ° C. The notch is 10 thousandths (0.254 millimeters) in radius. The impact is perpendicular to the flow lines on the plate from which the bar is cut. The Izod results are reported in ft-lb / in. Impact resistance is also measured by the Izod test ("Weldline") according to ASTM Designation D 256-84 (Method A) at room temperature (23-25 ° C), but with respect to a sample that forms with a butt joint in a double gate mold. The sample has no notch, and is placed in the lathe, in such a way that the union is 1 millimeter above the upper surface of the jaws of the lathe. The results of the joint line are also reported in ft-lb / in. The percentage of elongation at break is measured according to ASTM Designation D 638-84 at a rate of 5.08 centimeters per minute with respect to a drawbar that has been placed under a tension of 0.5 percent, while being submerged in a 60 weight percent isooctane bath and 40 weight percent toluene for 5 minutes. After being removed from the bathroom, the sample is allowed to dry without tension for at least 24 hours before the test. The percentage of elongation at break is also measured with respect to a drawbar that has not been subjected to a bath with solvent. The results are expressed as "elongation / wet" and "elongation / dry", respectively. The percentage of retention of length ("retention") is calculated by dividing the value of the percentage of elongation obtained with respect to a sample that has received the bath with solvent, as described above (elongation / wet), between the value of the percentage of elongation obtained with respect to the sample of the same formulation that has not received the bath with solvent (elongation / dry). The "viscosity" is determined by placing a disk molded from the composition between two plates, each of which rotates in a reciprocating manner through an arc of 0.1 radian with a frequency of 1 second, while the disk is maintained at 270 ° C. The energy consumption required to maintain the mentioned arc and the frequency, is proportional to the viscosity of the composition. The viscosity is exposed in poise.

Table I, Contents and Properties of Controls A-E and Example I The data in Table I demonstrate that, although polycarbonate has a high impact resistance in certain aspects, it has very little solvent resistance. The addition of an olefin-based modifier to the polycarbonate, such as LLDPE or EPR, definitely results in a composition having a solvent resistance that greatly improves upon that of the polycarbonate, but in which case the low impact resistance is sacrificed completely. it owns the polycarbonate by itself, as indicated by the values of the junction line. The use of MBS as a modifier in a polycarbonate composition produces a material that has an unbearable impact resistance but has poor solvent resistance. In contrast, Example 1, where polycarbonate is mixed with a substantially linear ethylene polymer, shows a desirable balance of relatively good values in both impact strength and solvent resistance properties, and overcomes the problem caused by the above modifiers that , although they improve a polycarbonate property, they caused a decline in the other properties. Example 1 shows no tendency toward delamination, and the lower viscosity of Example 1 makes it easier to process. The content of the formulation of Examples 2-3 and of the F-H Controls is given below in Table II, in parts by weight of the total composition.

In Table II: "Polycarbonate" is a polycarbonate of Bisphenol-A having a weight average molecular weight of 23,000; "M B S" s p o p o l m e r o d methacrylate / styrene / butadiene (Paraloid ™ 8963 from Rohm &Haas), - "HDPE" is high density polyethylene; "GRC" is a grafted core-shell elastomer prepared from acrylonitrile, butadiene, and styrene; and "ITP!" is a substantially linear ethylene polymer, as described above as the component (b), which has a density of approximately 0.87 grams per cubic centimeter.

The following tests are carried out on the Examples 2-3 and the F-H Controls, and the results of these tests are also shown in Table II: Izod and Union Line tests are performed as described above. "P" indicates that the impact is perpendicular to the flow lines on the plate from which the bar is cut. "PL" indicates that the impact is parallel to the flow lines in the plate from which the bar is cut. The deviation temperature under load (D.T.U.L. ") is measured in accordance with ASTM Designation D 648-82 at 66 psi.

The tensile strength to the yield ("yield"), the resistance to the traction to the break ("breaking"), and the percentage of elongation to the break ("elongation"), and the traction module ("module T") , all are determined in accordance with ASTM Designation D 638. All except elongation are reported in psi. The flexural modulus ("Module F") is determined in accordance with ASTM D 790. The results are reported in psi.

Table II, Contents and Properties of the F-H Controls and Examples 2-3 A review of the data in Table II with respect to the FH Controls and Examples 2-3, indicates that mixing of even a small amount of a substantially linear ethylene polymer in a polycarbonate composition containing a conventional impact modifier , produces a composition that has a desirable balance of several properties. For example, when the HDPE of Control F is replaced with a substantially linear ethylene polymer, the resulting composition, Example 2, shows a distinctly improved low-temperature Izod. Although there is a decrease in the binding line with respect to Example 2, the value remains at an acceptable level, and other properties show essentially comparable values. In a similar manner, when a portion of the GRC of Control G, or all of the HDPE of Control H, is replaced with a substantially linear ethylene polymer, the resulting composition, Example 3, shows better Izod at low temperature, tensile strength. to breaking, and Elongation, while maintaining an acceptable level of performance with respect to the other properties. In addition, Examples 2-3 show no tendency towards delamination.

Claims (15)

1. A composition of matter, which comprises, in admixture: (a) polycarbonate, and (b) a substantially linear ethylene polymer having: (i) a melt flow ratio, I10 / I2, which is greater than, or equal to, 5.63; (ii) a molecular weight distribution, Mw / Mn, that is less than, or equal to, the value: (I10 / I2) - 4.63; and (iii) a critical tear rate to the setting of the surface melt fracture of at least 50 percent greater than the tear rate critical to the setting of the surface melt fracture of a linear olefin polymer having approximately the same I2 and Mw / Mn.

2. The composition of claim 1, which further comprises a styrenic copolymer.

3. The composition of claim 2, wherein the styrenic copolymer is an aromatic vinyl / vinylnitrile modified rubber copolymer. The composition of claim 3, wherein the rubber modifier in the vinyl aromatic vinylnitrile copolymer modified with rubber, is polymerized from a diene, an olefin monomer, an alkyl acrylate or methacrylate, or a mixture thereof, or a mixture of one or more of the above with an aromatic vinyl compound or a vinylnitrile compound. The composition of claim 3, wherein the aromatic vinyl / vinyl nitrile modified rubber copolymer is acrylonitrile / butadiene / styrene copolymer. The composition of claim 1, which further comprises an elastomeric impact modifier selected from an aromatic vinyl / diene block copolymer, a core-shell graft copolymer, or a mixture thereof. The composition of claim 1, which further comprises a polyester. 8. The composition of claim 7, which further comprises a styrenic copolymer. The composition of claim 7, which further comprises an elastomeric impact modifier selected from an aromatic vinyl / diene block copolymer, a core-shell graft copolymer, or a mixture thereof. The composition of claim 1, which further comprises an olefin molding polymer. The composition of claim 1, wherein the substantially linear ethylene polymer has a density greater than about 0.850 grams per cubic centimeter. The composition of claim 1, wherein the substantially linear ethylene polymer has a melt flow ratio, I] / I2, of about 6.5 to 15. The composition of claim 1, wherein the polymer substantially linear ethylene has a molecular weight distribution (Mw / Mn) of about 1.5 to 2.5. 1

4. The composition of claim 1, which further comprises a filler. 1

5. The composition of claim 1, in the form of a molded or extruded article.