MXPA97003125A - Polycarbonate compositions that have demolishing properties - Google Patents

Abstract

A thermoplastic molding composition comprising polycarbonate and a complex ester is disclosed. It has been found that the ester, which is represented by (see formula), where p is an integer from 2 to 8, q is an integer from 7 to 13 and R and R 'represent, independently, a group CxH2x + 1, in the that x is an integer from 8 to 24, gives the composition excellent mold loading and desmold properties

Description

POLY.CARBONATE COMPOSITIONS THAT HAVE REMOVAL PROPERTIES FIELD OF THE INVENTION The invention relates to compositions for molding thermoplastics and, in particular, to compositions based on polycarbonates. COMPENDIUM OF THE INVENTION A thermoplastic molding composition comprising polycarbonate and a complex ester is described. It has been found that the ester, which is represented by COR 'I O f CH3 (CH2) p-CH- (CH2) q-COOR where p is an integer from 2 to 8, q is an integer from 7 to 13 and R and R 'represent, independently, a group CxH2x + ?, where x is an integer from 8 to 24, imparts excellent properties to the composition of mold loading and demoulding.

BACKGROUND OF THE INVENTION Polycarbonates are thermoplastics widely used in industry because they present an attractive series of physical and mechanical properties. There is however a disadvantage that is associated with their work and is that they have poor mold release properties. In the injection molding application, this disadvantage translates into relatively long cycle times. It has been possible to shorten the cycle times by injection molding at higher temperatures and using demolding agents. To improve the demolding properties of the compositions, long chain aliphatic carboxylic acid esters of monohydric and trihydric alcohols have been incorporated into the polycarbonate compositions: US Patent 4,007,150 describes the use of perfluoroalkanesulfonic acid amides and / or cyclic ammonium salts of these acids as release agents. The corresponding technology is described in US Pat. No. 3,784,595 which relates to polycarbonate molding compositions having improved mold release properties containing a trihydric alcohol ester and aliphatic carboxylic acid saturated with C? -22- According to that document, these esters are effective demolding agents, without at the same time giving rise to a degradation of the polycarbonate which reduces the quality in a measurable manner. Also relevant in this context is US Pat. No. 3,836,499 which discloses esters of C10-35 monovalent alcohols and saturated aliphatic Cs-25 monocarboxylic acids.

DETAILED DESCRIPTION OF THE INVENTION Aromatic polycarbonates within the scope of the present invention include homopolycarbonates and copolycarbonates and mixtures thereof. Suitable polycarbonates have a weight average molecular weight of 10,000-200,000, preferably 20,000-80,000 and their melt flow rate, by D-1238 of ASTM at 300 ° C, is from about 1 to 65 g / 10 minutes, preferably about 2-24 g / 10 minutes. They can be prepared, for example, by the known biphasic interface process from a carbonic acid derivative such as phosgene and dihydroxy compounds by polycondensation (see German Patent Publications, German Offenlegunsschriften, 2,063,050, 2,063,052, 1,570. 703; 2,211,956; 2,211,957 and 2,248,817; French Patent 1,561,518; and the monograph by H. Schnell, "Chemistry and Polycarbonate Physics", Interscience Publishers, New York, NY 1964, which are incorporated herein, all of them, as reference). In the present context, suitable dihydric compounds for the preparation of the polycarbonates of the invention correspond to the following structural formulas (1) and (2). where A represents an alkylene group with 1 to 8 carbon atoms, an alkylidene group with 2 to 8 carbon atoms, a cycloalkylene group with 5 to 15 carbon atoms, a cycloalkylidene group with 5 to 15 carbon atoms, a group carbonyl, an oxygen atom, a sulfur atom, - SO-, or -S02- or a radical represented by e and g represent, both, a number from 0 to 1; Z represents F, Cl, Br or C 1-4 alkyl and if there are several radicals Z as substituents on an aryl radical, these may be the same or different one from another d represents an integer from 0 to 4; and f represents an integer from 0 to 3. Among the dihydroxy compounds useful in the practice of the invention are hydroquinone, resorcin, bis- (hydroxyphenyl) -alkanes, bis- (hydroxyphenyl) -ethers, bis- (hydroxyphenyl) -ketones, bis - (hydroxyphenyl) -sulphoxides, bis- (hydroxyphenyl) -sulfides, bis- (hydroxyphenyl) -sulfones, a, a-bis- (hydroxyphenyl) -diisopropyl-benzenes, as well as their alkylated compounds in the nucleus. These and other suitable aromatic dihydroxy compounds are described, for example, in U.S. Patent 3,028,356; 2,999,835; 3,148,172; 2,991,273; 3,271,367; and 2,999,846, all incorporated herein by reference. Other examples of suitable bisphenols are 2,2-bis- (4-hydroxyphenyl) -propane (bisphenol A), 2,4-bis- (4-hydroxyphenyl) -2-methyl-butane, 1,1-bis- (4 -hydroxyphenyl) -cyclohexane,, a'-bis (4-hydroxyphenyl) -p-diisopropylbenzene, 2,2-bis- (3-methyl-4-hydroxyphenyl) -propane, 2,2-bis- (3-chloro- 4-hydroxyphenyl) -propane, bis- (3, 5-dimethyl-4-hydroxyphenyl) -methane, 2,2-bis- (3, 5-dimethyl-4-hydroxyphenyl) -propane, bis, (3, 5- dimethyl-4-hydroxyphenyl) -sulfide, bis- (3, 5-dimethyl-4-hydroxyphenyl) -sulfoxide, bis- (3, 5-dimethyl-4-hydroxyphenyl) -sulfone, dihydroxybenzophenone, 2,4-bis- ( 3, 5'-dimethyl-4-hydroxyphenyl) -cyclohexane, a, a'-bis- (3, 5-dimethyl-4-hydroxyphenyl) -p-diisopropylbenzene and 4,4'-sulphonyl diphenol. Among the examples of preferred aromatic biphenols in particular are 2, 2-bis- (4-hydroxyphenyl) -propane, 2,2-bis- (3, 5-dimethyl-4-hydroxyphenyl) -propane and 1,1-bis- (4-hydroxyphenyl) -cyclohexane. The most preferred bisphenol is 2,2-bis- (4-hydroxyphenyl) -propane (bisphenol A). The polycarbonates of the invention can carry in their structure units derived from one or more of the suitable bisphenols. Suitable resins in the practice of the invention include polycarbonates, copolycarbonates and phenolphthalein-based terpoly carbonates, such as those described in U.S. Patent 3,036,036 and 4. 210,741, incorporated herein, both, by reference. The polycarbonates of the invention can also be branched by their condensation with small amounts, for example 0.05-2.0 mole percent (relative to the bisphenols) of polyhydroxy compounds. Polycarbonates of this type are described, for example, in the German Patent Publications German Offenlegungsschriften 1,570,533; 2,116,974 and 2,113,374; British Patents 885,442 and 1,079,821 and U.S. Patent 3,544,514. The following are some examples of polyhydroxy compounds that can be used for this purpose; phloroglucin; 4,6-dimethyl-2, 6-tri- (4-hydroxyphenyl) -heptane; 1, 3, 5-tri- (-hydroxyphenyl) -benzene; 1,1,1- tri- (4-hydroxyphenyl) -ethane; tri- (4-hydroxyphenyl) -phenylmethane; 2, 2-bis- [4, 4- (4,4'-dihydroxydiphenyl)] -cyclohexyl-propane; 2, 4-bis- (4-hydroxy-l-isopropylidino) -phenol; 2,6-bis- (2'-dihydroxy-5'-methylbenzyl) -4-methyl-phenol; 2,4-dihydroxybenzoic acid; 2- (4-hydroxyphenyl) -2- (2,4-dihydroxyphenyl) -propane and 1,4-bis- (4,4'-dihydroxytriphenylmethylbenzene.) Some of the other polyfunctional compounds are 2,4-dihydroxybenzoic acid, Trimesic acid, cyanuric chloride and 3,3-bis- (-hydroxyphenyl) -2-oxo-2,3-dihydroindole In addition to the aforesaid polycondensation process, other processes for the preparation of the polycarbonates of the invention are polycondensation in homogeneous phase and transesterification Suitable methods are described in US Patents 3,028,365, 2,999,846, 3,153,008, and 2,991,273, which are incorporated herein by reference.The preferred process for the preparation of polycarbonates is the • interfacial polycondensation process Other synthesis methods can also be used in the production of polycarbonates of the invention such as those described in US Pat. No. 3,912,688 incorporated herein by reference. Suitable polycarbonate resins can be found in commerce, for example, Makrolon FCR, Makrolon 2600, Makrolon 2800 and Makrolon 3100, all of which are bisphenol-based homopolycarbonate resins that differ in their respective molecular weights and are characterized in that their Melt flow rates (MFR), according to ASTM D-1238, are approximately 16.5-24, 13-16, 7.5-13.0 and 3.5-6.5 g / 10 minutes, respectively . These products are from Bayer Corporation of Pittsburg, Pennsylvania. The polycarbonate resin suitable in the practice of the invention is known and its structure and methods of preparation are described, for example, in U.S. Patent 3,030,331; 3,169,121; 3,395,119; 3,729,447; 4,255,556; 4,260,731; 4,369,303 and 4,714,746 all incorporated herein by reference. The release agent according to the invention is a complex ester which corresponds to COR 'I O i CH3 (CH2) p-CH- (CH2) q-COOR where p is an integer from 2 to 8, preferably 4 to 6, q is an integer from 7 to 13, preferably 9 to 11 and R and R ', independently, represent a group CxH2? + ?, where x is an integer of 8 to 24, preferably 14 to 20. Advantageously, the complex ester is at least one member selected from the group consisting of stearyl stearoyl stearate, isostearyl stearoyl stearate and isocetyl stearoyl stearate. Suitable complex esters in the context of the present invention can be found commercially, for example under the trade name HETESTER of Bernel Chemical Company, Ine. The amount of complex ester added to the carbonate polymer is a positive amount which is sufficient to impart improved demolding property to the composition as compared to the corresponding composition that does not contain the complex ester. Preferably, the composition of the invention contains about 0.1 to 2, more preferably 0.2 to 1.0 percent relative to the weight of the carbonate polymer. The incorporation of the complex ester to the polycarbonate can be carried out using conventional techniques. These include drum mixing of the complex esters which are usually in the form of waxy solids or liquids with polycarbonate nodules followed by extrusion (at about 280-300 ° C) to form a strip which is then cut into nodules. Alternatively, the complex ester can be introduced in the form of a molten liquid directly into the molten polycarbonate in an extruder. Another alternative is represented by the incorporation of the demolding agent to the solid polycarbonate during the manufacture of the resin. In that case, the complex ester is mixed as a solution in a solvent with the p-barbonate solution before reaching the devolatilization screw, or it is introduced without solvent directly into the polycarbonate melt. The method for the determination of the demolding force for the purpose of comparing the efficiencies of the release agents is well known. Essentially the injection cylinder of an injection molding machine, for example a Newbury of 113.36 g (4 ounces), is equipped with a pressure transducer to measure and record force during the ejection phase of molding a disc flat 90 mm diameter. The mold is characterized because it has four ribs of decreasing section of 5 mm in height by 1-2 mm of intersection thickness resting on a grid. There are four ejector tips at the intersections of the ribs and four ejector tips along the perimeter of the disc. The mold is designed with a minimum conicity on the ribs to favor the tendency of the piece to stick to the core. The moldings are injected at a melt temperature of 280 ° C with a cycle time of 45 seconds between injections. The mold is maintained at a solidification temperature of 79.5 ° C. The values of the demolding force given below represent averages of the last twelve consecutive values of the hydraulic ejection pressure of the mold taken after the mold has stabilized, usually after 25-30 ejections. The invention is further illustrated, without being to be construed as limited by the following examples in which all parts and percentages are by weight unless otherwise specified. EXAMPLES Experimental Example 1 A complex ester useful in the present invention was prepared as follows: Step 1: to a reaction vessel of suitable size, equipped with stirrer, temperature controller, distillation column, variable ratio reflux condenser and inlet nitrogen, 542 grams (g) of stearic acid (acid number 203, 2.0 moles) and 600 g of 12-hydroxystearic acid (acid number 179, 2.0 moles) and 0.114 g of dibutyltin oxide catalyst are added. . The stirred molten mixture is heated to 215 ° C under purging with nitrogen to facilitate removal of water from the reaction. The purging is stopped with nitrogen when the water temperature of the reaction vapor pressure in the filled distillation column falls below 80 ° C at which point a full vacuum is applied. The molten mixture is kept under full vacuum at 215 ° C with stirring until the acid number has fallen to about 110 (about 8 hours) at which time the first stage of the reaction is completed. Step 2: The partial ester formed above is converted to the complex ester by reacting the contents of the reaction vessel of step 1 with 665 grams of ALFOL 20 + alcohol (a mixture of about 4: 2: 1 of Eicosonal, Docosanol and Tetracosanol from Vista Chemical Co.). This reaction is carried out over a period of 5 hours at a temperature of 215 ° C with stirring and purging of nitrogen to facilitate the separation of water of reaction. When the temperature in the filled distillation column falls below 80 ° C, a full vacuum is applied and the nitrogen purge is stopped. The molten mixture is kept under full vacuum at 215 ° C with stirring until the acid number has dropped to 3 or less (about 7 hours). A tan-colored waxy solid having a melting point of about 40 ° C was obtained.

EXAMPLE 2 A complex ester useful in the present invention was prepared in two steps as follows: Step 1: To a reaction vessel of suitable size provided with stirrer, temperature controller, distillation column, variable ratio reflux condenser and inlet nitrogen are added 2034 g of stearic acid (acid number 203, 7.5 moles) and 2251 q of 12-hydroxystearic acid (acid number 179, 7.5 moles) and 0.4 g of dibutyltin oxide catalyst. The stirred molten mixture is heated to 205 ° C under purging with nitrogen to facilitate the separation of water of reaction. The purging is stopped with nitrogen when the water temperature of the reaction steam pressure in the filled distillation column falls below 80 ° C at which time a complete vacuum is applied. The molten mixture is kept under full vacuum at 200-206 ° C with stirring until the acid number has dropped to about 110 (about 10 hours) at which time the first stage of the reaction is completed. In step 2, the partial ester formed is converted to a complex ester by reaction of the content of the reaction vessel of step 1 with 2123 grams of stearyl alcohol. This reaction is carried out over a period of 15 hours at a temperature of 205 ° C with stirring and purging of nitrogen or vacuum to facilitate the separation of water from the reaction until the acid number has fallen to 7 or less . A tan-colored waxy solid having a melting point of about 40 ° C was obtained.

EXAMPLE 3 Compositions according to the invention were prepared and their demolding properties were determined. The results are collected later. In the preparation of the compositions, the carbonate polymer was a bisphenol A-based homopolycarbonate and was characterized by a melt flow index of 19 g / 10 minutes, as determined by D-1238 of ASTM (Makrolon resin 2508-1112). , a commercial product of Bayer Corporation); the representative demolding agent of the present invention, cited as MSE in the table was the complex ester prepared according to Example 1 above. A comparative example was prepared where the release agents were trimethylol propane tripelargonate (cited in the table as TPT). All compositions contained a small amount (0.10% by weight) of a thermal stabilizer that is not critical to the present invention. The compositions contained 99.15% by weight of polycarbonate and approximately 0.74% by weight of the said release agent, Table 1 Melt flow rates 1 melt flow rate in g / 10 minutes per D-1238 of ASTM measured at 300 ° C, 1200 g charge Table 2 'Release force (barias) The results indicate that the demolding agent of the invention is effective to reduce the demolding force in proportion to the content thereof in the composition. If it is compared with the corresponding demolding force of a 1 Polycarbonate composition that does not contain mold release agents (25.5) The results demonstrate that the agent of the invention is more effective than TPT which is a known mold release agent for polycarbonate resins. The edge color of the compositions containing 0.75% of the release agent of the invention (MSE) was yellow. The corresponding compositions containing TPT were transparent. The loading characteristics of the mold. the composition of the invention were evaluated as shown below. The composition of the invention (Composition B below), which contained polycarbonate and 0.75% stearyl stearoyl stearoyl was evaluated by comparing it with Makrolon 2558 composition (Composition A below), a demoulding grade polycarbonate composition having an index of very similar melt flow. The results are shown below: Table 3 1- not determined Although the invention has been described in detail in the foregoing for illustrative purposes, it is to be understood that this detail responds solely to that purpose and that variations may be made therein by those skilled in the art without departing from the spirit and scope of the invention. except as limited by the claims.

Claims (10)

Claims

1. A thermoplastic molding composition comprising a carbonate polymer and an effective amount of an ester that is represented by COR '0 CH3 (CH2) p-CH- (CH2) q-COOR where p is an integer from 2 to 8, q is an integer from 7 to 13 and R and R1 represent, independently, a group CxH2x + ?, where x is an integer from 8 to 24., said quantity being sufficient for imparting to the composition improved mold release properties compared to a corresponding composition that does not contain the said complex ester. The composition according to claim 1 wherein p is an integer from 4 to 6. 3. The composition according to claim 1 wherein q is an integer from 9 to 11. 4. The composition according to claim 1 wherein x is an integer of 14 to 20. The composition according to claim 1 wherein the complex ester is at least one member selected from the group consisting of stearyl stearoyl stearate, isostearyl stearoyl stearate and isocetyl stearoyl stearate. 6. The composition according to claim 1 wherein said carbonate polymer is a bisphenol-A based homopolycarbonate. 7. The composition according to claim 1 wherein said amount is from about 0.1 to 2 percent relative to the weight of said carbonato-polymer. The composition according to claim 1 wherein said amount is from about 0.2 to 1.0 percent relative to the weight of said carbonate polymer. 9. A thermoplastic molding composition comprising a bisphenol-A-based homopolycarbonate and having about 0.2 to 1.0 percent of a complex ester which is represented by COR 'l 0 I CH3 (CH2) p-CH- (CH2) q-COOR where p is an integer from 4 to 6, q is an integer from 9 to 11 and R and R 'represent, independently, a group CxH2x + ?, wherein x is an integer from 14 to 20. The composition according to claim 9 wherein the complex ester is at least one member selected from the group consisting of stearyl stearate. stearoyl, isostearyl stearoyl stearate and isocetyl stearoyl stearate.