Polycarbonate/Polyestercarbonate composition

Abstract: A composition comprising a. about 10 to 90 weight percent of an aromatic polycarbonate in admixture with b. about 90 to 10 weight percent of copolyestercarbonate having repeating units of the structure wherein: R is independently selected from halogen, monovalent hydrocarbon, and monovalent hydrocarbonoxy radicals; R 1 is independently selected from halogen, monovalent hydrocarbon, and monovalent hydrocarbonoxy radicals; W is selected from divalent hydrocarbon radicals, and n and n 1 are independently selected from integers having a value of from 0 to 4 inclusive; b is either zero or one; X is an alkylene group of about 6 to 18 carbon atoms, inclusive; d is from about 2 to 30 mole percent of the total units c+d; and a and b calculated as weight percent of a plus b.

Description: Polycarbonates are well known amorphous polymers known for their transparency, toughness, and impact resistance. Copolyestercarbonates are also well known. These polymers having both ester and carbonate linkages of the properties which are similar to polycarbonates. A copolyestercarbonate has been described in serial numbers 07/627,517 filed December 14, 1990, 07/476,068 filed January 30, 1990 and 07/455,118 filed December 22, 1989 WO 91/09896. This copolyestercarbonate has aromatic carbonate units and aromatic aliphatic ester units wherein the aromatic unit is a dihydric phenol and the ester unit is an aliphatic alpha omega dicarboxylic acid. This substantially differs from the totally aromatic copolyestercarbonates which are well known from the prior art particularly USP 4,522,980 and other relevant patents. As is observed from the data on the copolyestercarbonate of this invention it has the advantage of better flow and processability at a lower temperature than an ordinary aromatic polycarbonate of the same intrinsic viscosity. However heat related properties of the copolyestercarbonates such as DTUL are lowered. It has now been found that by blending aromatic polycarbonate with the copolyestercarbonate disclosed herein over a specific weight percent range, certain physical properties change over the range while other properties demonstrate very little if any change over the range. SUMMARY OF THE INVENTION In accordance with the invention there is an admixture comprising from 10-90 weight percent of a copolyestercarbonate having the repeating units of the structure: (i) wherein: R is independently selected from halogen, monovalent hydrocarbon, and monovalent hydrocarbonoxy radicals; R 1 is independently selected from halogen, monovalent hydrocarbon, and monovalent hydrocarbonoxy radicals; W is selected from divalent hydrocarbon radicals, -S-, -S-S-, -O-, n and n 1 are independently selected from integers having a value of from 0 to 4 inclusive; b is either zero or one; X is an alkylene group of 6 to 18 carbon atoms, inclusive; d is from 2 to 30 mole percent of the total units c+d; and (ii) 90-10 weight percent of an aromatic polycarbonate (i) and (ii) calculated as weight percent of (i) plus (ii), wherein the difference in intrinsic viscosity, measured at 25°C in methylene chloride, between (i) and (ii) is at least 0.04 dl/g and the composition does not contain an impack modifier. DETAILED DESCRIPTION OF THE INVENTION Dihydric phenols which are useful in preparing the copolyestercarbonate of the invention may be represented by the general formula wherein: R is independently selected from halogen, monovalent hydrocarbon, and monovalent hydrocarbonoxy radicals; R 1 is independently selected from halogen, monovalent hydrocarbon, and monovalent hydrocarbonoxy radicals; W is selected from divalent hydrocarbon radicals, -S-, -S-S-, -O-, n and n 1 are independently selected from integers having a value of from 0 to 4 inclusive; and b is either zero or one. The monovalent hydrocarbon radicals represented by R and R 1 include the alkyl, cycloalkyl, aryl, aralkyl and alkaryl radicals. The preferred alkyl radicals are those containing from 1 to 12 carbon atoms. The preferred cycloalkyl radicals are those containing from 4 to 8 ring carbon atoms. The preferred aryl radicals are those containing from 6 to 12 ring carbon atoms, i.e., phenyl, naphthyl, and biphenyl. The preferred alkaryl and aralkyl radicals are those containing from 7 to 14 carbon atoms. The preferred halogen radicals represented by R and R 1 are chlorine and bromine. The divalent hydrocarbon radicals represented by W include the alkylene, alkylidene, cycloalkylene and cycloalkylidene radicals. The preferred alkylene radicals are those containing from 2 to 30 carbon atoms. The preferred alkylidene radicals are those containing from 1 to 30 carbon atoms. The preferred cycloalkylene and cycloalkylidene radicals are those containing from 6 to 16 ring carbon atoms. The monovalent hydrocarbonoxy radicals represented by R and R 1 may be represented by the formula - OR 2 wherein R 2 is a monovalent hydrocarbon radical of the type described hereinafore. Preferred monovalent hydrocarbonoxy radicals are the alkoxy and aryloxy radicals. Some illustrative non-limiting examples of the dihydric phenols falling within the scope of Formula II include: 2,2-bis(4-hydroxyphenyl)propane (bisphenol-A); 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane; 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane; 1,1-bis(4-hydroxyphenyl)cyclohexane; 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane; 1,1-bis(4-hydroxyphenyl)decane; 1,4-bis(4-hydroxyphenyl)propane; 1,1-bis(4-hydroxyphenyl)cyclododecane; 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclododecane; 4,4 -dihydroxydiphenyl ether; 4,4 -thiodiphenol; 4,4 -dihydroxy-3,3 -dichlorodiphenyl ether; and 4,4 -dihydroxy-2,5-dihydroxydiphenyl ether. Other useful dihydric phenols which are also suitable for use in the preparation of the above polycarbonates are disclosed in U.S. Patent Nos. 2,999,835; 3,028,365; 3,334,154; and 4,131,575, all of which are incorporated herein by reference. The carbonate precursor utilized in the invention can be any of the standard carbonate precursors such as phosgene, diphenyl carbonate and the like. When using an interfacial process or a bischloroformate process it is also preferred to use a standard catalyst system well known in the synthesis of polycarbonates and copolyestercarbonates. A typical catalyst system is that of an amine system such as tertiaryamine, amidine or guanidine. Tertiary amines are generally employed in such reactions. Trialkylamines such as triethylamine are generally preferred. The monomer which supplies the ester units in the copolyestercarbonate is an aliphatic alpha omega dicarboxylic acid or ester precursor from 8 to 20 carbon atoms preferably 10 to 12 carbon atoms. The aliphatic system is normal, branched or cyclic. Examples of the system include azelaic acid, sebacic acid, dodecanedioic acid, C14, C18 and C20 diacids. The normal saturated aliphatic alpha omega dicarboxylic acids are preferred. Sebacic, and dodecanedioic acid are most preferred. Mixtures of the diacids can also be employed. It should be noted that although referred to as diacids, any ester precursor can be employed such as acid halides, preferably acid chloride, diaromatic ester of the diacid such as diphenyl, for example the diphenylester of sebacic acid. With reference to the carbon atom number earlier mentioned, this does not include any carbon atoms which may be included in the ester precursor portion, for example diphenyl. The copolyestercarbonates of the invention can be prepared by the known methods, for example those appearing in Quinn US-A 4,238,596 and Quinn and Markezich US-A 4,238,597. Examples of such processes include the formation of acid halides prior to the reaction of the ester forming group with the dihydric phenol and then followed by phosgenation. Still further, the basic solution process of Goldberg in the US-A 3,169,121 reference utilizing a pyridine solvent can also be employed while also using the dicarboxylic acid per se. A melt process utilizing the diesters of the alpha omega dicarboxylic acids can also be employed. An example of such a compound is the diphenylester of sebacic acid. After substantial experimentation, it has been found that a preferred process for making the copolyestercarbonates of this invention exists. The process of Kochanowski, USP 4,286,083 (083) was initially utilized and then improved upon. It was found that lower diacids such as adipic acid were not incorporated into the polymer backbone to any great extent. Rather, one had to go up to higher carbon atom dicarboxylic acids before any significant incorporation of diacid into the backbone was observed. We have found that the diacid is preferentially introduced as the preformed salt, preferably an alkali metal such as sodium into the interfacial reaction reactor. The water phase is maintained at an alkaline pH preferably from about 8 to 9 for most of the phosgenation period and then raising the pH to a level of about 10 to 11 for the remainder of the phosgenation time period which is generally a minimum of 5%. In order to control molecular weight, it is standard practice to utilize a chain stopping agent which is a monofunctional compound. This compound when reacting with the appropriate monomer provides a non-reactive end. Therefore the quantity of chain stopping compound controls the molecular weight of the polymer. Bulkier chain terminators than phenol should provide substantially better retention of physical properties such as impact. Examples of these bulkier substituents include paratertiarybutylphenol, isononyl phenol, isooctyl phenol, cumyl phenols such as meta and paracumyl phenol, preferably paracumyl phenol, as well as chromanyl compounds such as Chroman I. The copolyestercarbonate of this invention with the standard endcapping reagent possesses a substantially lowered glass transition temperature, Tg, therefore providing processability at a lower temperature. Surprisingly accompanying this low temperature processability are substantially equivalent physical properties as a standard polycarbonate of the same intrinsic viscosity as the inventive composition and very high flow rates. The aliphatic alpha omega dicarboxylic acid ester is present in the copolyestercarbonate in quantities from 2 to 30 mole percent, based on the dihydric phenol. Generally with quantities below 2 mole percent the Tg is insufficiently lowered and significantly altered flow rate is not observed. Above 30 mole percent, the physical properties of the copolyestercarbonate are significantly hindered in comparison to the polycarbonate without the aliphatic ester linkages. Preferred mole percents of aliphatic alpha omega dicarboxylic acid ester are from 5 to 25 and more preferably 7 to 20 mole percent of the dihydric phenol. The weight average molecular weight of the copolyestercarbonate can generally vary from 10,000 to 100,000 as measured by GPC, using a polystyrene standard corrected for polycarbonate. A preferred weight average molecular weight is from 16,000 to 40,000. The copolyestercarbonate has the following structural units. where R, R 1 , n, n 1 , W and b have been previously described and X is an alkylene group of 6 to 18 carbon atoms, inclusive. The d repeating unit is present in the copolyestercarbonate in from 2 to 30 mole percent of the total of the repeating units c+d, X is preferably 8 to 16 carbon atoms, inclusive. The alkylene system is preferably saturated and is normal, branched, cyclic or alkyl substituted cyclic. The mole percent of d is preferably 5 to 25 and more preferably 7 to 20 mole percent. For example, when 5 moles of bisphenol-A reacts completely with 4 moles of phosgene and 1 mole of dodecanedioic acid, the resulting copolyestercarbonate is said to have 20 mole percent ester content. That is, the d unit is 20 mole percent of the c + d units. Of course the aromatic polycarbonates which are utilized in the invention are those which are used in the standard manner and which can be readily prepared from dihydric phenol and carbonate precursor. The previous dihydric phenols which can be employed for the copolyestercarbonate of course the same type of dihydric phenols which can be used for the aromatic polycarbonate. In like manner the carbonate precursors which can be utilized for the copolyestercarbonate may be also used for the polycarbonate. The aromatic polycarbonate can vary from 10 to 90 weight percent of the total aromatic polycarbonate and copolyestercarbonates while the copolyestercarbonate is from 90 to 10 weight percent of the two. It is preferred to use 20 to 80 weight percent of the copolyestercarbonate in conjunction with 80 to 20 weight percent of the polycarbonate. It is also preferred to have the composition components endcapped with large, bulky endcapping agents such as cumylphenol, isooctylphenol, isononyl phenol or a chroman. Preferably the polycarbonate copolyestercarbonate composition is essentially absent or completely free from polyester, rubbery materials such as acrylonitrile butadiene styrene or methylmethacrylate butadiene styrene materials or mixtures of the polyester and rubbery materials as well as from other impact modifiers known as useful in polycarbonate, for example polyolefins and the like. Although various mixtures of the copolyestercarbonate and polycarbonate can be employed, it is preferred to employ a mixture wherein there is a significant difference in the molecular weight of the two resins. Generally with reference to intrinsic viscosity units of dl/g measured at 25°C in methylene chloride, a difference of 0.04 I.V., or greater, preferably 0.06 I.V. units or greater is significant. For example, a resin with an intrinsic viscosity (I.V.) of 0.52-0.57 dl/g is combined with a resin with an I.V. of 0.42-0.47 dl/g, I.V. measured in methylene chloride at 25°C. Either resin can be the higher I.V., however the copolyestercarbonate is preferred. When resins are of similar I.V., most properties remain essentially constant while other property(ies) can vary substantially. The I.V. referred to above is measured on the powder. The compositions can be blended in the usual manner and processed in the usual manner. Below are examples of the invention. These examples are meant to exemplify the invention and are not intended to narrow the examples. In the examples below, the polycarbonate of the invention was prepared by standard means and is bisphenol-A polycarbonate. The copolyestercarbonate is a 10 mole% dodecanedioate ester content bisphenol-A copolyester-carbonate. In Example 1 the polycarbonate is endcapped with phenol. In Example 2, the polycarbonate and in Examples 1 and 2 the copolyestercarbonate is endcapped with paracumylphenol. Abbreviations used in the Table have the following meanings: MVI melt Viscosity Index measured at 280°C and 12 Newtons. s.d. standard deviation T.S. tensile strength INI Impact Notched Izod as measured by ASTMD256 Vicat- 50N, 120°C per hour DTUL measured at 1.82 MPa, ASTM D648 DSC Tg glass transition temperature BI Biaxial Instrumented Impact, ASTM D3763 3.2mm thickness X 101.6mm diameter; 12.77 mm Tup PB Partial Break MF melt flow - ASTM D1238, condition O DTUL264 at 1.82 MPa, ASTM D648 TY tensile yield, units MPa per ASTM D638 TE tensile elongation, % TB tensile break, MPa, ASTM D638 6.4mm NI 6.4mm Notched Izod, J/M ASTM D256 1.8mm NI 1.8mm Notched Izod, J/M ASTM D256 BI Biaxial Instrumented Impact, ASTM D3763 3.2mm thickness X 101.6mm diameter; 12.77 mm Tup YI yellowness index in accordance with ASTM D1925-70 %T percent transmission in accordance with ASTM D1925-70 %H percent haze Example 1 In Example 1 the polycarbonate and copolyestercarbonate were extruded at 260°C (500°F) and molded with parts at 299°C (570°F). As is observed from the data, the thermal properties, (Vicat, HDT, Tg) show a steady downward trend with increasing PEC content while the melt viscosity index shows an almost 4 fold increase! The remainder of the tested properties are essentially the same. Therefore, an admixture with strikingly more processability is obtained while maintaining virtually all the properties of the original polycarbonate. Example 2 The bisphenol-A polycarbonate was extruded at 260°C (500°F) and molded at 299°C (570°F). The dodecanedioate bisphenol-A copolyestercarbonate was extruded at 260°C (500°F) and molded at 299°C (570°F). The blend was extruded at 260°C (500°F) and molded at 299°C (570°F). As shown by the data in Table II, the addition of a lower I.V. polycarbonate to a higher I.V. copolyester-carbonate brings up the melt flow substantially for easier processing and results in a general titration of properties except for one - tensile elongation (TE). In this single property, the addition of the polycarbonate having a sharply lower TE (63±17) to the copolyestercarbonate having a sharply higher TE (98±2) brought little or no change at the various dilutions of copolyestercarbonate with polycarbonate. Rather the value stayed about the same. This is a highly unexpected result. Additionally the low temperature impact strength of the blended polymer up to at least a 50 weight percent PC content demonstrated exceptional retention of the copolyestercarbonate impact resistance.

Claims: A composition comprising (i) 10 to 90 weight percent of an aromatic polycarbonate in admixture with (ii) 90 to 10 weight percent of copolyester-carbonate having repeating units of the structure wherein: R is independently selected from halogen, monovalent hydrocarbon, and monovalent hydrocarbonoxy radicals; R 1 is independently selected from halogen, monovalent hydrocarbon, and monovalent hydrocarbonoxy radicals; W is selected from divalent hydrocarbon radicals, -S-, -S-S-, -O-, n and n 1 are independently selected from integers having a value of from 0 to 4 inclusive; b is either zero or one; X is an alkylene group of 6 to 18 carbon atoms, inclusive; d is from 2 to 30 mole percent of the total units c+d; and (i) and (ii) calculated as weight percent of (i) plus (ii), wherein the difference in intrinsic viscosity, measured at 25°C in methylene chloride, between (i) and (ii) is at least 0.04 dl/g and the composition does not contain an impact modifier. A composition comprising (i) 20 to 80 weight percent of linear aromatic polycarbonate in admixture with (ii) 80 to 20 weight percent of copolyester-carbonate having repeating units of the structure wherein: R is independently selected from monovalent hydrocarbon, and monovalent hydrocarbonoxy radicals; R 1 is independently selected from monovalent hydrocarbon, and monovalent hydrocarbonoxy radicals; W is selected from divalent hydrocarbon radicals, -S-, -S-S-, -O-, n and n 1 are independently selected from integers having a value of from 0 to 4 inclusive; b is either zero or one; X is an alkylene group of about 6 to 18 carbon atoms, inclusive; d is from 2 to 30 mole percent of the total units c+d; and (i) and (ii) calculated as weight percent of (i) plus (ii), wherein the difference in intrinsic viscosity, measured at 25°C in methylene chloride in dl/g between (i) and (ii) is at least 0.04 dl/g, the melt Viscosity index measured at 280°C and 12 Newtons increases proportionally with the weight percent of copolyester-carbonate, the tensile elongation, measured in percent, is substantially the same for all proportions of copolyestercarbonate and the tensile break measured in Mpa according to ASTM D638, of the composition is greater than either the copolyester carbonate or polycarbonate alone. The composition in accordance with claim 1 wherein (i) is from 25 to 75 wt.% and (ii) is from 25 to 75 wt.%. The composition in accordance with claim 1 or claim 2 wherein (i) is bisphenol-A polycarbonate and (ii) is bisphenol-A copolyester-carbonate. The composition in accordance with any preceding claim wherein X is a saturated normal alkylene group. The composition in accordance with claim 5 wherein X has from eight to ten carbon atoms. The composition in accordance with any preceding claim wherein the mole percent of ester in (ii) is from 5 to 25 mole percent. The composition in accordance with any preceding claim wherein intrinsic viscosity difference between (i) and (ii) is 0.06 dl/g. The composition in accordance with any preceding claim wherein added polyesters, rubbery materials, polyolefins and impact modifiers known as useful in polycarbonates are essentially absent from the composition. The composition in accordance with any preceding claim wherein n=o and the aromatic polycarbonate is prepared from bisphenol-A and carbonate precursor.

Inventors: BOUTNI OMAR MOHAMED, FONTANA LUCA PIETRO, MORGAN SARAH ELIZABETH, BOUTNI, OMAR MOHAMED, FONTANA, LUCA PIETRO, MORGAN, SARAH ELIZABETH
Applicants: GEN ELECTRIC, GENERAL ELECTRIC COMPANY
Application year: 1992
Main classification: C08L69
IPC codes: C08L69, C08L67