GB1567517A - Polycarbonate moulding compositions - Google Patents

Description

(54) POLYCARBONATE MOLDING COMPOSITIONS (71) We, GENERAL ELECTRIC COMPANY. a corporation organised and existing under the laws of the State of New York. United States of America, of 1 River Road, Schenectady 12305, New York, United States of America, do hereby declare the invention.

for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention is directed to a thermoplastic molding composition comprising an aromatic carbonate polymer and from 0.1 to 3.0 weight percent. based on the weight of the polycarbonate composition, of an ester.

Thermoplastic compositions containing a release agent so as to facilitate disjoining a shaped article in contact with a shaping and cooling surface such as a mold are known in the art. Specifically, it is known from U.S. Patents 3,784,595 and 3,836.499 that the addition of esters of particular alcohols and acids to polycarbonates results in the ease of mold release of these polymeric products when injection molded.

However, in order to be an effective mold release agent an additive besides releasing the article from a mold should be compatible during processing, not adverselv affect the Physical properties of the end product; not contribute undesirable color or color drift; and be easily added to the resin. Also, it is important that the mold release agent does not plate out on the surface of the mold or the molded part.

It has now been found that certain precisely defined esters of certain organic acids and certain alcohols can be incorporated into a thermoplastic aromatic carbonate polymer which results in a composition which when formed into shaped articles release easily from the mold. In addition, the composition of the present invention is compatible with the polycarbonate melt. No apparent degradation of the polymer properties results from the addition of the ester. The ester additives aid in processing the aromatic polycarbonate polymer composition by reducing its apparent melt viscosity which results in improved moldability. No plate out is apparent in either the surface of the mold or the molded part whereby the original surface characteristics of the molded composition are retained.The additives also act synergistically with known ultraviolet stabilizers for polycarbonates to enhance ultraviolet light stability.

Esters which are effective in accordance with the invention are the reaction products, obtainable according to known processes. of saturated aliphatic monocarboxylic and dicarboxylic acids selected from the following formulae:

where n is from 5 to 34, such as valeric acid. caproic acid. capric acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid. melissic acid. tetratriacontoic acid. glutaric acid, adipic acid and azelaic acid, with alcohols, containing no hydrogen atoms on any carbon atom beta to the hydroxy group and selected from the following general formulae::

wherein n is 1 to 20;

wherein RX and R2 are independently alkyl and substituted alkyl of 1 to 1(1 carbon atoms or R1 together with R2 form the remainder of a 5 or 6 membered ring;

wherein R3 and R5 are independently alkyl and substituted alkyl of 1 to 4 carbon atoms and R4 is alkylene of 1 to 4 carbon atoms or -(CH2),,-O-(CH2)a- wherein a is an integer of from 1 to 4:

wherein R4 is alkvlene of 1 to 4 carbon atoms or -(CH2),-O-(CH2),,- wherein a is an integer from 1 to 4 and mixtures thereof.Illustrative alcohols include az (x- dihydroperfluoropropanol, neopentylene glycol. pentaerythritol. ditrimethylolpropane and dipentaerythritol.

Examples of the esters to be used herein include pentaerythrityl tetrastearate and neopentylene glycol distearate. Mixtures of such esters from acids which occur naturally are also effective and included herein.

The esters are used in amounts of from 0.10 to 3.0 weight percent. based on the weight of the composition.

The incorporation of the ester in the polycarbonate composition can be effected by admixing it with granules of the polycarbonate composition and subsequently extruding these through an extruder under standard conditions. The esters may also be incorporated when the polycarbonate is manufactured by dissolving them in a solvent in which the polycarbonate is dissolved and subsequently recovering the polymer composition from the solvent bv known methods.

The aromatic carbonate polymers employed in the practice of this invention are homopolymers and copolymers and mixtures thereof that are prepared by reacting a dihvdric phenol with a carbonate precursor.

The dihydric phenols that can be employed are bisphenols such as bis(4-hydroxyphenyl) methane. 2,2-bis(4-hydroxyphenyl) propane (hereinafter referred to as bisphenol-A), 2.2-bis(4-hydroxy-3-methylphenyl) propane, 4,4-bis(4-hydroxyphenyl) heptane, 2,2-bis(4 hydroxv-3.5-dichlorophenyl) propane, and 2.2-bis(4-hydroxy-3 5-dibromophenyl) prop ane, dihvdric phenol ethers such as bis(3-hvdroxvphenol) ether, and bis(3,5-dichloro-4hydroxyphenyl) ether. dihydroxydiphenyls such as p,p'-dihydroxydiphenyl and 3,3' dichloro-4.4'-dihydroxydiphenyl:: dihydroxyaryl sulfones such as bis(4-hydroxyphenyl) sulfone and bis(3,5-dimethyl-4-hydroxyphenyl) sulfone. dihydroxy benzenes, such as resorcinol and hydroquinone, halo- and alkvl-substituted dihydroxy benzenes such as 1 ,4-dihydroxy-2,5-dichlorobenzene and 1 ,4-dihydroxy-3-methylbenzene, and dihydroxy diphenvl sulfoxides such as bis(4-hydroxyphenyl) sulfoxide, and bis(3,5-dibromo-4hydrophenyl) sulfoxide. A variety of additional dihydric phenols are also available to provide carbonate polymers and are disclosed in U.S.Patents 2,999,835, 3,028.365 and 3.153.008. Also suitable for preparing the aromatic carbonate polymers are copolymers prepared from any of the above copolymerized with halogen-containing dihydric phenols such as 2,2-bis(3,5-dichloro-4-hydroxyphenyl) propane or 2,2-bis(3,5-dibromo-4hydroxyphenyl) propane. It is, of course, possible to employ two or more different dihydric phenols or a copolymer of a dihydric phenol with a glycol or with hydroxy or acid terminated polyester, or with dibasic acid in the event a carbonate copolymer or interpolymer rather than a homopolymer is desired for use in the composition of this invention. Also employed in the practice of this invention may be blends of any of the above materials to provide the aromatic carbonate polymer.

The carbonate precursor may be either a carbonyl halide, a carbonate ester or a haloformate. The carbonyl halides which can be employed herein are carbonyl bromide, carbonyl chloride and mixtures thereof. Typical of the carbonate esters which may be employed herein are diphenyl carbonate, di-(halophenyl) carbonates such as di (chlorophenyl) carbonate, di-(bromophenyl) carbonate, di-(trichlorophenyl) carbonate or di-(tribromophenyl) carbonate, di-(alkylphenyl) carbonate such as di-(tolyl) carbonate, di-(naphthyl) carbonate, di-(chloronaphthyl) carbonate, phenyl tolyl carbonate, and chlorophenyl chloronaphthyl carbonate, or mixtures thereof. The haloformates suitable for use herein include bishaloformates of dihydric phenols (bischloroformates of hydroquinone) or glycols (bishaloformates of ethylene glycol, neopentyl glycol or polyethylene glycol).While other carbonate precursors will occur to those skilled in the art, carbonyl chloride also known as phosgene is preferred.

Also included are the polymeric derivatives of a dihydric phenol, a dicarboxylic acid and carbonic acid. These are disclosed in U.S. Patent 3,169.121 which is incorporated herein by reference.

The aromatic carbonate polymers are prepared by employing a molecular weight regulator, an acid acceptor and a catalyst. The molecular weight regulators which can be employed include monohydric phenols such as phenol. chroman-I. paratertiarybutylphenol, parabromophenol and primary and secondary amines. Preferably, phenol is employed as the molecular weight regulator.

A suitable acid acceptor may be either an organic or an inorganic acid acceptor. A suitable organic acid acceptor is a tertiary amine and includes such materials as pyridine, triethylamine, dimethylaniline or tributylamine. The inorganic acid acceptor may be one which can be either a hydroxide. a carbonate, a bicarbonate. or a phosphate or an alkali or alkaline earth metal.

The catalysts which are employed herein can be any of the suitable catalvsts that aid the polymerization of bisphenol-A with phosgene. Suitable catalysts include tertiary amines such as, for example, triethylamine, tripropvlamine. n , n-dimethylaniline, quaternary ammonium compounds such as, for example, tetraethvlammonium bromide, cetyl triethyl ammonium bromide, tetra-n-heptylammonium iodize tetra-n-propyl ammonium bromide, tetramethylammonium chloride, tetramethvl ammonium hydroxide, tetra-nbutylammonium iodide, benzyltrimethylammonium chloride and quaternary phosphonium compounds such as, for example, n-butyltriphenyl phosphonium bromide and methyltriphenyl phosphonium bromide.

Also, included herein are branched polycarbonates wherein a polyfunctional aromatic compound is reacted with the dihydric phenol and carbonate precursor to provide a thermoplastic randomly branched polycarbonate.

These polyfunctional aromatic compounds contain at least three functional groups which are carboxyl, carboxylic anhydride, haloformyl or mixtures thereof. Examples of these polyfunctional aromatic compounds include: trimellitic anhydride. trimellitic acid. trimellityl trichloride, 4-chloroformyl phthalic anhydride. pyromellitic acid. pyromellitic dianhydride, mellitic acid, mellitic anhydride, trimesic acid. benzophenonetetracarboxylic acid, benzophenonetetracarboxylic anhydride and diphenolic acid.

Obviously, other materials can also be employed with the aromatic carbonate polymer composition of this invention and include such materials as antistatic agents, other mold release agents, thermal stabilizers such as phosphites. ultraviolet light stabilizers such as hydroxyaryl benzotriazoles and reinforcing fillers such as glass and other inert fillers, foaming agents, colorants and flame retardant additives.

The following examples are set forth to illustrate the invention. Unless otherwise specified, where parts or percents are mentioned, they are parts or percents by weight.

Example I (Comparative) A polycarbonate molding composition is prepared by extruding a homopolymer of 2,2-bis(4-hydroxyphenyl) propane, (hereinafter referred to as bisphenol-A), prepared by reacting essentially equimolar amounts of bisphenol-A and phosgene in an organic medium with triethylamine. sodium hydroxide, and phenol. under standard conditions. The polymer is fed into an extruder operated at about 265"C. and the extrudate strands are chopped into pellets. The pellets are injection molded under standard conditions into test specimens of about 3 inches by 2 inches by 1/8 inch at 600"F and 700"F. The specimen is designated as Sample A Control.Thermal stability to discoloration is measured in accordance with ASTM Yellowness Index Test D1925 on samples molded at 6000F and 700"F. The results are set forth in Table I.

Example II (Samples D-G comparative) Example I is repeated except that 0.3 weight percent of the following additives are mixed with the polycarbonates: Sample B pentaerythrityl tetrastearate Sample C poly(neopentylene azelate) Sample D organopolysiloxane fluid Sample E glycerol tristearate Sample F Loxiol (R.T.M.) G 47 (stearyl fatty acid esters of C2(,-C24 fatty acids) Sample G stearic acid Each of the compositions are processed and molded into test specimens as in Example I.

The test specimens are subjected to the test as described in Example I and the results are set forth in Table I.

TABLE I Yellowness Index as Molded at Sample 600"F 700"F A700 -600 F A (Control) .1 10.4 10.5 B -.2 6.9 7.1 C -.1 6.8 6.9 D -.4 6.7 7.1 E -.3 9.2 9.5 F -.6 8.7 9.3 G -.5 10.4 10.9 Example III (Samples I-K comparative) Example I is repeated except that 0.3 weight percent of the following additives are mixed with the polycarbonate: Sample H pentaerythritvl tetrastearate Sample I organopolysiloxane fluid Sample J glycerol tristearate Sample K Loxiol G 47 Each of the compositions is formed into pellets as in Example I.The pellets are injection molded into test specimens of open box configuration 3 inches x 3 inches x 1 inch deep with 0.1 inch sidewall thickness in a low draft mold equipped with a pressure transducing ejector svstem which measures the force required to release the molded part of the mold and records this force on a pen recording instrument. The results are set forth in Table II.

TABLE II Sample Release Force (psi) A (Control) Did not release. injector pins broke part H 9.700 I 12.400 J 10.100 K 12,000 Example IV Example I is repeated except that 0.35 weight percent of pentaerythrityl tetrastearate is mixed with the polycarbonate. This is designated as Sample L. The processability of the pellets is determined by their apparent melt viscosity - as determined by melt flow as measured by ASTM D1238 Condition 0. The molecular weight of the composition is determined by measuring intrinsic viscosity in a standard way utilizing a 0.4 (volume/weight percent) polymer solution in dioxane at 30"C. The results are set forth in Table III.

TABLE III Sample Melt Flow I.V.

A (Control) 13.3 0.496 L 17.3 0.503 Example V (Comparative) Example I is repeated except that 0.3 weight percent of a commercially available hydroxyphenylbenzotriazole [Tinuvin (R.T.M.) P] is admixed with the polycarbonate. The polymer is formed into pellets and injected molded into test specimens as described in Example I. The test specimens are exposed to a 4000 watt mercury vapor lamp for 7 days and 14 days. The discoloration is measured in accordance with ASTM Yellowness Index Test D1925 on samples molded at 6000F. The test specimens are designated as Sample M.

The results are set forth in Table IV.

Example VI (Comparative) Example V is repeated except that 0.3 weight percent of organopolysiloxane fluid is added to the polymer. The composition is processed, molded into test specimens and subjected to the test as described in Example V. The test specimens are designated as Sample N. The results are set forth in Table IV.

Example VII Example V is repeated except that 0.3 weight percent of pentaerythrityl tetrastearate is added to the polymer. The composition is processed. molded into test specimens and subjected to the test as described in Example V. The test specimens are designated as Sample O. The results are set forth in Table IV.

TABLE IV Yellowness Index Sample 7 days 14 days M 9.1 33.6 N 11.0 36.8 0 8.1 29.8 The data in Table I shows that a polycarbonate composition of the present invention (Samples B and C) has a smaller change in Yellowness Index number, i.e., less discoloration of the polymer and therefore better thermal stabilitv. than the polymer without additive (Sample A) and polymer with commercially available additives (Samples D, E, F and G). The data of Table II shows that an article molded from a polymer composition of the present invention (Sample H) requires less pressure to release a molded part than commercially available additives (Samples I. J. K). The control sample (Sample A) without additive would'not release.

The data of Table III illustrates the processabilitv of a composition of the present invention (Sample L) since the melt flow increased while the I.V. did not significantly change indicating no degradation of molecular weight as compared with the control containing no additive.

The data of Table IV illustrates the synergistic effect when a commercially available ultraviolet stabilizer is added to a polvcarbonate composition of the present invention (Sample 0) over a composition containing ultraviolet stabilizer alone (Sample M) and a composition containing ultraviolet stabilizer and a commercially available mold release agent (Sample N). This is shown bv the lower Yellowness Index number.

WHAT WE CLAIM IS.

1. A thermoplastic molding composition comprising an aromatic carbonate polymer and from 0.1 to 3.0 weight percent based on the weight of the polycarbonate composition,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. pellets is determined by their apparent melt viscosity - as determined by melt flow as measured by ASTM D1238 Condition 0. The molecular weight of the composition is determined by measuring intrinsic viscosity in a standard way utilizing a 0.4 (volume/weight percent) polymer solution in dioxane at 30"C. The results are set forth in Table III. TABLE III Sample Melt Flow I.V. A (Control) 13.3 0.496 L 17.3 0.503 Example V (Comparative) Example I is repeated except that 0.3 weight percent of a commercially available hydroxyphenylbenzotriazole [Tinuvin (R.T.M.) P] is admixed with the polycarbonate. The polymer is formed into pellets and injected molded into test specimens as described in Example I. The test specimens are exposed to a 4000 watt mercury vapor lamp for 7 days and 14 days. The discoloration is measured in accordance with ASTM Yellowness Index Test D1925 on samples molded at 6000F. The test specimens are designated as Sample M. The results are set forth in Table IV. Example VI (Comparative) Example V is repeated except that 0.3 weight percent of organopolysiloxane fluid is added to the polymer. The composition is processed, molded into test specimens and subjected to the test as described in Example V. The test specimens are designated as Sample N. The results are set forth in Table IV. Example VII Example V is repeated except that 0.3 weight percent of pentaerythrityl tetrastearate is added to the polymer. The composition is processed. molded into test specimens and subjected to the test as described in Example V. The test specimens are designated as Sample O. The results are set forth in Table IV. TABLE IV Yellowness Index Sample 7 days 14 days M 9.1 33.6 N 11.0 36.8 0 8.1 29.8 The data in Table I shows that a polycarbonate composition of the present invention (Samples B and C) has a smaller change in Yellowness Index number, i.e., less discoloration of the polymer and therefore better thermal stabilitv. than the polymer without additive (Sample A) and polymer with commercially available additives (Samples D, E, F and G). The data of Table II shows that an article molded from a polymer composition of the present invention (Sample H) requires less pressure to release a molded part than commercially available additives (Samples I. J. K). The control sample (Sample A) without additive would'not release. The data of Table III illustrates the processabilitv of a composition of the present invention (Sample L) since the melt flow increased while the I.V. did not significantly change indicating no degradation of molecular weight as compared with the control containing no additive. The data of Table IV illustrates the synergistic effect when a commercially available ultraviolet stabilizer is added to a polvcarbonate composition of the present invention (Sample 0) over a composition containing ultraviolet stabilizer alone (Sample M) and a composition containing ultraviolet stabilizer and a commercially available mold release agent (Sample N). This is shown bv the lower Yellowness Index number. WHAT WE CLAIM IS.

1. A thermoplastic molding composition comprising an aromatic carbonate polymer and from 0.1 to 3.0 weight percent based on the weight of the polycarbonate composition,

of an ester of an acid selected from saturated aliphatic monocarboxylic and dicarboxylic acids of the following formulae:

where n is from 5 to 34, and mixtures thereof, with an alcohol selected from the following general formulae:

wherein n is 1 to 20;

wherein R and R2 are independently alkyl and substituted alkyl of l to 10 carbon atoms or R1 together with R2 form the remainder of a 5 or 6 membered ring::

wherein R3 and R5 are independently alkyl and substituted alkyl of 1 to 4 carbon atoms and R4 is alkylene of 1 to 4 carbon atoms or -(CH2)a-O-(CH2)a- wherein a is an integer from 1 to 4;

wherein R4 is alkylene of 1 to 4 carbon atoms or -(CH2);,-O-(CH2),1- wherein a is an integer from 1 to 4, and mixtures thereof.

2. A composition as claimed in claim 1. wherein the alcohol is ,a- dihydroperfluoropropanol, neopentylene glycol. pentaerythritol. ditrimethylolpropane or dipentaerythritol.

3. A composition as claimed in claim 1 or 9. wherein the ester is pentaerythrityl tetrastearate or neopentylene glycol distearate.

4. A composition as claimed in any preceding claim, which includes a stabilizing amount of an ultraviolet light stabilizer.

5. A composition as claimed in claim 4, wherein the ultraviolet light stabilizer is a hydroxyphenylbenzotriazole.

6. A thermoplastic molding composition as claimed in claim 1 and substantially as hereinbefore described.