CA1062394A - Phenolphthalein-dihydroxy aromatic compound polycarbonates - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Phenolphthalein-dihydroxy aromatic compound polycarbonates are disclosed wherein the mole ratio of phenolphthalein to dihydroxy aromatic compound is in the range from 0.05 to 0.7 and the molecular weight is from 25,000 to 60,000.
These copolymers exhibit improved impact strength, heat resistance, creep resistance, tensile strength at high temperatures and stress crack resistance.

Description

This invention relates to high molecular weight phenolphthalein-dihydroxy aromatic compound poly-carbonates having a mole ratio of phenolphthalein to dihydroxy aromatic compound in the range from 0.05 to 0.7 and a molecular weight which is greater than 25,000 to 60,000.
Polycarbonate resins made from 4,4'-isopropy-lidenediphenol (bisphenol A) have been known to the plastics art for some time and are characterized as having exceptionally high impact strength. Although this property - and other desirable properties for such conventional : polycarbonates make them useful for certain applications, the polymers' relatively low resistance to the effects of heat, stress, and organic solvents prevents their use in many other applications. These properties and limitations are described in detail in the book, "Chemistry and Physics ` of Polycarbonates", written by H. Schnell and published by Interscience Publishers (1964).
Improved polycarbonate resins made from phenol-phthalein are described in U. S. Patent 3,036,036 (1962) and an article written by P. W. Morgan (Journal of Polymer Science: Part A, Vol. 2, page 437, (1964)). These resins have higher melting points, higher heat distortion temperatures and better solvent resistance to chlorinated alkane solvents than resins made from 4,4'-isopropylidenediphenol. Copoly-carbonates of phenolphthalein and 4,4'-isopropylidenediphenol were also described. However, the molecular weights of these ; copolycarbonates were so low that only fibers or films were produced from them and molded articles made from such products have been found to have virtually no impact strength.
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-: , . ; . -It has been known for many years that the homopolycarbonate of 4,4'-isopropylidenediphenol possesses a combination of properties which make it especially useful as an engineering thermoplastic. It has also been well known, however, that the material has properties which significantly limits its use in certain applications. In particular, the tendency of molded parts of the polymer to craze or crack when placed under stress, the tendency of molded parts of the polymer to dissolve or be swelled or craze or crack when contacted with usual organic solvents, especially when also under stress and the tendency of molded ; parts of the polymer to loose impact strength or otherwise change when aged at moderately high temperatures such as 100C to 125C are reported as properties which limit the use of the polymer. Also, the frictional properties such as coefficient of friction and abrasion resistance of molded parts of the polymer are reported to be such as to preclude its general use in applications where these properties are important, such as in construction of gears or bearings.
An improved polycarbonate has been described in U. S. Patent 3,036,036 (1962) which contains phenolphthalein residues in the polycarbonate chain. Although this resin ; was described as having high molecular weight, the weight-average molecular weight of the products described therein as determined by gel permeation chromatography were not sufficiently high to allow molding of the polymer into parts suitable for the varied applications described above for the homopolycarbonate of 4,4'-isopropylidenediphenol, i.e., for use as an engineering thermoplastic.
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It has now been discovered that copolycarbonates prepared from phenolphthalein and 4,4'-isopropylidenediphenol which have a weight average molecular weight as determined by gel permeation chromatography of about 25,000 or greater are not only suitable for use as an engineering thermo-plastic but surprisingly exhibit significant improvements in many of the properties listed above which limits the application of the homopolycarbonate of 4,4'-isopropylidene-diphenol. However, the improvement in certain of these .~ 10 properties is only minimal if the mole ratio of phenol-phthalein to 4,4'-isopropylidenediphenol residues in the copolycarbonate is about 0.05 or lower and a significant ~ decrease in certain other properties, such as impact : strength, is observed if this mole ratio is about 0.7 or greater. Further, these copolycarbonates retain the improved properties as taught in U. S. Patent 3,036,036 (1962) of .`. higher melting point, higher heat distortion temperature, etc. and also exhibit properties, such as increased resistance to transmission of oxygen or resistance to foaming at high temperatures which make them suitable for use in applications where the homopolycarbonate of 4,4'-isopropylidenediphenol is unsuitable.
The present invention resides in a thermoplastic polycarbonate resin characterized by a chain of divalent .'. 25 phenolphthalein radicals mixed with divalent dihydroxy-: aromatic radicals in the mole ratio range of phenolphthalein `I to dihydroxyaromatic compound from 0.05 to 0.7 wherein the phenolphthalein and dihydroxyaromatic radicals are linearly ~ connected by carbonate ester groups, said resin having a -~. 30 weight average molecular weight from 25,000 to 60,000 as ~, determined by gel permeation chromatography.
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' 17~766-F -3-For the purposes of this invention, the terms divalent phenolphthalein radicals and divalent dihydroxy aromatic radicals means that the radicals are the residues obtained by removing the hydroxyl hydrogens from the phenolphthalein and dihydroxy aromatic compounds.
Preferably, the mole ratio range is from 0.12 to 0.43 with the range from 0.18 to 0.33 being the most preferred range.
Preferably, the molecular weight range as measured by gel permation chromatography is from 25,000 to 60,000 with the range from 33,000 to 50,000 being the most preferred range.
It is to be understood that the mole ratio of phenolphthalein to diaromatic compound is a convenient - 15 index to the amount of phenolphthalein content in the copolymer. In making these copolymers the monomers are substantially all converted to polymers so that if, for example, one mole of phenolphthalein is reacted with two moles of a dihydroxy aromatic compound such as 4,4-iso-propylidenediphenol, one obtains a mole ratio in the resulting polymer of 0.5 (phenolphthalein to bis A) or 33 mole percent of phenolphthalein. Thus, the reciprocal of the mole of dihydroxy compound used with each mole of phenolphthalein gives the mole ratio of the copolymer and the lower mole ratios used herein (0.05) represents the polymer resulting from the condensation of phosgene with one mole of phenolphthalein and twenty moles of a dihydroxy aromatic compound. The latter can also be designated as a copolymer having 4.7 mole percent of phenolphthalein.

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; 17~766-F _4_ In addition to the superior properties shown above over both homopolycarbonates of 4,4'-isopropylidene-diphenol and the copolycarbonates taught in U. S. Patent 3,036,036, the copolycarbonates made from phenolphthalein (A) and 4,4'-isopropylidenediphenol (B) wherein the mole ratio of A/B was between 0.08 and 0.70 for copolymers of weight average molecular weight greater than 25,000, were found by certain small scale tests to have improved resis-tance to burning, improved resistance to crazing or cracking under compressive stress, improved resistance to scratching, and improved gas barrier properties. The small scale burning tests are not intended to reflect hazards presented by these or any other materials under actual fire conditions.
The invention is illustrated by Figures 1, 2 and 3 of the drawings. Figure 1 illustrates how the impact strength increases dramatically where the phenolphthalein/
~ 4,4~-isopropylidenediphenol copolymers have a mole ratio - of (A) phenolphthalein to (B) 4,4'-isopropylidenediphenol of in the range from 0.08 to 0.31 if the molecular weight is also greater than about 27,000. This is shown in Figure l by the A/B ratio. Similar polymers, i.e., the controls which have an A/B ratio in the range from 0.91 to 1.0, are illustrated by the dotted line.
Figure 2 illustrates how the impact strength decreases with increasing values of the molecular ratio A/B which is defined above.
Figure 3 illustrates the superior tensile creep properties of the copolymers of this invention. The time in hours i8 plotted on a logarithmic scale and shows that the percent strain for example 14 is almost constant ,,, .
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through a 50 hour test whereas the percent strain of the control is constantly increasing with time throughout the same test.
In the examples that follow, the invention is illustrated by the use of copolymers of phenolphthalein and 4,4'-isopropylidenediphenol (bisphenol A). However, it is to be understood that the invention is applicable to a wide variety of related dihydroxy aromatic compounds such as those represented by the general formula HO~ (A)n~OH
., X
wherein A is a divalent hydrocarbon radical containing 1-15 O o O
~ carbon atoms, -S-, -S-S-, -S-, -S-, -O-, and -C-, X is ';' O
independently hydrogen, chlorine, bromine, flourine, or a monovalent hydrocarbon radical such as an alkyl group of ` 1-4 carbons, an aryl group of 6-8 carbons such as phenyl, .. tolyl, xylyl, an oxyalkyl group of 1-4 carbons and an oxyaryl group of 6-8 carbons and n is 0 or 1.
One group of suitable dihydric phenols are those illustrated below:
1,1-bis(4-hydroxyphenyl)-1-phenyl ethane . 1,1-bis(4-hydroxyphenol)-1,1-diphenyl methane 1,1-bis(4-hydroxyphenyl)cyclooctane 1,1-bis(4-hydroxyphenyl)cycloheptane 1,1-bis(4-hydroxyphenyl)cyclohexane 1,1-bis(4-hydroxyphenyl)cyclopentane ., ,.
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2,2-bist3-propyl-4-hydroxyphenyl)decane 2,2-bis(3,5-dibromo-4-hydroxyphenyl)nonane 2,2-bis(3,5-isopropyl-4-hydroxyphenyl)nonane 2,2-bis(3-ethyl-4-hydroxyphenyl)octane 4,4-bis(4-hydroxyphenyl)heptane

3,3-bis(3-methyl-4-hydroxyphenyl)hexane 3,3-bis(3,5-dibromo-4-hydroxyphenyl)pentane 2,2-bis(3,5-difluoro-4-hydroxyphenyl)butane 2,2-bis(4-hydroxyphenyl)propane (Bis A) 1,1-bis(3-methyl-4-hydroxyphenyl)ethane l,l-bis(4-hydroxyphenyl)methane.
Another group of dihydric phenols useful in the practice of the present invention include the dihydroxyl diphenyl sulfoxides such as for example:
bis(3,5-diisopropyl-4-hydroxyphenyl)sulfoxide bis(3-methyl-5-ethyl-4-hydroxyphenyl)sulfoxide bis(3,5-dibromo-4-hydroxyphenyl)sulfox~de bis(3,5-dimethyl-4-hydroxyphenyl)sulfoxide bis(3-methyl-4-hydroxyphenyl)sulfoxide bis(4-hydroxyphenyl)sulfoxide.
Another group of dihydric phenols which may be used in the practice of the invention includes the dihydroxyaryl sulfones such as, for example:
bis(3,5-diisopropyl-4-hydroxyphenyl)sulfone bis(3-methyl-5-ethyl-4-hydroxyphenyl)sulfone bis(3-chloro-4-hydroxyphenyl)sulfone ~ bis(3,5-dibromo-4-hydroxyphenyl)sulfone .~ bis(3,5-dimethyl-4-hydroxyphenyl)sulfone i bis(3-methyl-4-hydroxyphenyl)sulfone i 30 bis(4-hydroxyphenyl)sulfone.

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- Another group of dihydric phenols useful in the practice of the invention includes the dihydroxydiphenyls:
3,3',5,5'-tetrabromo-4,4'-dihydroxydiphenyl 3,3'-dichloro-4,4'-dihydroxydiphenyl 3,3'-diethyl-4,4'-dihydroxydiphenyl 3,3'-dimethyl-4,4'-dihydroxydiphenyl p,p'-dihydroxydiphenyl.
Another group of dihydric phenols which may be used in the practice of the invention includes the dihydric phenol ethers-bis(3-chloro-5-methyl-4-hydroxyphenyl)ether bis(3,5-dibromo-4-hydroxyphenyl)ether bis(3,5-dichloro-4-hydroxyphenyl)ether bis(3-ethyl-4-hydroxyphenyl)ether , 15 bis(3-methyl-4-hydroxyphenyl)ether -^~ bis(4-hydroxyphenyl)ether.
~" The invention is illustrated by the following i Tables I and II which are graphically illustrated in Figures 1 and 2, re~pectively.

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Mole Ratio Wt.-Avg. Notch Izod Polymer A/B (a) Mol. Wt. (b) Impact Strength (c) Control 1 0.91 17,452 <1 Control 2 0.08 19,247 2.5 Control 3 0.11 6,998 <1 Control 4 1.00 21,200 2.1 Control 5 1.00 27,300 2.3 Control 6 1.00 32,800 2.9 Control 7 1.00 39,900 2.2 Example 1 0.08 29,800 14.3 Example 2 0.08 31,400 15.0 Example 3 0.08 35,300 15.5 - (a) Mole ratio of phenolphthalein residues to 4,4'-isopropy-lidene residues in the copolycarbonates (b) by Gel Permeation Chromatograp~y (c) by ASTM Method D-256 (average of eight test bars) Table I shows the effect of molecular weight as determined by gel permeation chromatography, on impact strength, as determined by the notched izod impact test method (ASTM No. D-256), for a series of copolycarbonates containing a mole ratio of phenolphthalein to 4,4'-isopropy-lidenediphenol residues of 0.08 to 0.11 and for such a ; series wherein that mole ratio is 0.91 to 1Ø These ~ same data are shown in Figure 1 of the drawings to1 graphically illustrate the dual effect of molecular weight, as determined by gel permeation chromatography, and the above mole ratio on impact strength.
In Table II below is shown the effect of mole q ratio of phenolphthalein residues to 4,4'-isopropylidene-~ diphenol residues in the copolycarbonate on the impact ~ 30 strength for a series of copolymers of 30,000 to 40,000 'J
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Table II
Mole Ratio Wt.-Avg. Notch Izod Polymer A/B (a) Mol. Wt. (b) Impact Strength (c) Example 3 0.080 35,300 15.5 Example 4 0.080 34,000 16.5 Example 5 0.18 29,544 13.8 Example 6 0.181 32,200 12.1 Example 7 0.238 38,813 10.9 Example 8 0.308 30,508 10.9 Example 9 0.308 29,900 8.9 Example 10 0.308 34,335 8.5 Example 11 0.429 35,600 4.8 Example 12 0.429 33,200 4.0 Control 7 1.00 39,900 2.2 Control 8 1.50 33,900 2.3 ,.
!,,, (a) Mole ratio of phenolphthalein residues to 4,4'-isopropy-lidene diphenol residues (b) by Gel Permeation Chromatography '''! 20 (c) by ASTM Method D-256 ; It is to be understood that the copolymers of this invention are those having a weight-average molecular weight of at least 25,000 as determined by the gel permeation chromatography method. This method is described below and compared to other methods for determining the lecular ~3 weight of polymers. ~-Absolute values for the weight-average molecular weights of polycarbonates may be determined by such methods .~ ~ ,.. - ,.
; as sedimentation rates using the ultracentrifuge or 17,766-F -10-, -light-scattering measurements made on polymer solutions.
These methods are described in the book written by H.
Schnell, previously mentioned, and are very time-consuming.
In practice it is more common to perform absolute measurements one time and relate such measurements to the measurement of some property which is rapidly determined, such as relative viscosity of a polymer solution.
The relative viscosity or inherent viscosity of polymer solutions may be used to determine the molecular weights of two polymers differing only in molecular weights as they relate to each other but only qualitatively unless a calibration curve has been established using one of the absolute methods. For copolycarbonates it has been common practice to measure the relative viscosity of a series of polymers of different molecular weights and assume that these viscosities will be the same for any given molecular weight as those for a known polycar-bonate of similar structure for which absolute molecular weight determinations have been made, such as the homo-polycarbonate made from 4,4'-isopropylidenediphenol. This assumption is frequently valid, however, it also often introduces di~crepancies in the molecular weights found for the unknown copolycarbonate since the relative viscosity values are dependent on its structure, temperature, solvent, . .~.
concentration and to some extent the method by which it is measured. Further, molecular weights found for the unknown `` copolycarbonates are then highly dependent on the accuracyof the absolute values determined for the homopolycarbonate used as a standard.

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A more recent method for determination of the lecular weight of polymers is the use of gel permeation chromatography. The method is more rapidly performed than the measurement of relative viscosities, does not depend on the concentration of polymer in solution and also provides information on the molecular weight distri-bution of a polymer. It is especially convenient with polycarbonates since most of them are ~oluble in tetra-hydrofuran, the solvent most commonly employed in gel - -permeation chromatography. Details of the method are described in the book, "Modern Practice of Liquid Chromatography", edited by J. J. Kirkland and published by Wiley-Interscience (1971). The method, like that using relative viscosities of polymer solutions, depends on the ; 15 correlation of measurements made on an unknown polymer with the same measurements made on a similar polymer of : known molecular weight.
The following is a description of the gel permeation chromatography method used for determination of the molecular weights of the various copolycarbonates made from phenol-phthalein and 4,4'-isopropylidenediphenol which are described in the disclosure.
Samples of polymer were prepared for analysis by dissolving in tetrahydrofuran in such amount to make an approximately 2 weight percent solution. The solution ` (about 0.2 ml) was injected into a gel permeation chroma-tography instrument, such as one manufactured by Waters Associates~ Inc., which contained a 16' by 3/8" column i packed with polystyrene beads containing small pore~.
Eight feet of the column contained beads with a pore size .~

; 17,766-F -12-of 3 x 103 A and eight feet contained beads with a pore size of 3 x 10 A. Tetrahydrofuran was passed through the column and the polymer was thus eluted from the column selectively according to the size of the individual molecules in the polymer. The presence of the polymer in the eluent was detected by differential refractive index measurements. The quantity of the polymer found in each fraction of eluent was indicated by refractive index response and the molecular weight of the polymer in that fraction was indicated by the elution volume. The elution volume measurements and the refractive index measurements were used in equations, with the aid of a computer, for the calculation of molecular weights and molecular weight distribution as described in articles written by J. C.
Moore (J. Polymer Sci., A2, 835 (1964) and L. H. Tung, ~ et al., (J. Appl. Polymer Sci., 10 375, 1261, 1271 (1966)).
- For this calculation it is necessary that the gel permeation chromatography equipment and conditions be standardized i.e.
calibrated, using similar polymers of various known molecular weights. Thus the same type measurements were made under the same conditions on several homopolycarbonates of

4,4~-isopropylidenediphenol for which the absolute weight--average molecular weights had been determined by the light-scattering technique mentioned above. Similar measurements were also made on compounds of the structure O\ Me OH Me ~O\
CH2-CH-CH2-0~ ~ C ~3-o-cH2-cH-cH2-o ~ C-OE~-O-CH2-CH-CH2 ~e _ n ~e wherein n was 2, 4, 6 and 8. In this way the equipment and conditions were calibrated in the weight-average molecular weight range of 1000 to 50,000.
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~06Z394 In Table III is shown a comparison of the weight--average molecular weights as determined by relative viscosity measurements using published values for this relationship (W. F. Christopher and D. W. Fox, "Polycar-bonates", Reinhold Publishing Corp., 1962, page 42) with weight-average molecular weights as determined by the gel permeation chromatography method for a number of homo-polycarbonates of 4,4'-isopropylidenediphenol and - copolycarbonates containing phenolphthalein. It is believed that the weight-average molecular weight values determined by gel permeation chromatography are more accurate for the copolycarbonates than those values determined from viscosity measurements since the constants, ~; K and a, in the equation relating intrinsic viscosity to molecular weight [n ] = KMa are not known for the copoly-carbonates and will probably vary depending on the mole ratio of phenolphthalein residues to 4,4'-isopropylidene-dlphenol residues in the copolycarbonate~.

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The invention is further illustrated by the following tests which demonstrate the foaming and strength properties of the copolycarbonate~ of this invention at high temperatures.
Injection molded tensile bars (1/8 x 1/2 x 6-1/2") of various polymers were placed in an oven held at a constant temperature. They were placed, along their length, over an opening which was 7.5 cm wide. On some bars were placed standard weights in the center of the bars. After heating for a period of time the bars sagged in the center of the bar and after removing from the oven the amount of sagging ! (or inflection distance) was measured with a cathetometer.
After heating for one hour at 300F with a 100 gm standard weight in the center of the bars, the following inflection distances were noted in Table IV for the various polymers and copolymers.

TABLE IV
Molecular Mole Ratiol Inflection Distance, PolymerWt. (by GPC) A/8 mm Control 11 29,900 Bis A 22.3 ; Homopolymer Example 13 27,800 0.08 N.D.
Example 14 28,700 0.18 N.D.
` Example 15 33,046 0.238 N.D.
Control 1 17,452 0.91 could not make molded ~, specimen Control 3 6,998 0.11 could not make molded specimen 1 A/B z mole ratio of phenolphthalein to 4,4'-isopropylidene-` diphenol in copolycarbonate 2 N.D. = no deflection noted (beyond experimental error of measurement) ..
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'' ' ., . ' :' The product from Example No. 15 also supported a 200 gm weight under these conditions with no significant inflection distance noted (<2 mm).
After heating at 350F, some of the tensile bars sagged under their own weight and the inflection distance noted for this sagging increased with time. The following results were noted in Table V.

TABLE V
Inflection Distance in (mm) Polymer 72 hrs 147 hrs 188 hrs Control 11 95 125 138 ; Example 13 - - 35 Example 14 N.D. N.D. 3 Example 15 N.D. N.D. 3 Control 1 molecular wt. too low to make molded specimen Control 3 lecular wt. too low to make lded specimen N.D. = no deflection '~,'r On heating at 350F some of the tensile bars developed tiny bubbles throughout the bars which might be described as N foaming". Such foaming rendered the other-wise clear, transparent tensile bars opaque. The following res~lts in T~ble VI were observed.

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Appearance of Bubbles at:
Polymer 13 min. 72 hrs. 188 hrs.
Control 11 M.B. V.M.B. V.M.B.
Example 14 N.B. N.B. N.B.
Example 15 N.B. N.B. N.B.
Control 1 mol. wt. too low to make molded tensile bars Control 3 mol. wt. too low to make molded tensile bars M.B. = many bubbles N.B. = no bubbles V.M.B. = very many bubbles The product from Example No. 15 above did not exhibit any bubbles even after heating at 392F for 10 minutes.
The tensile strength of the various polymers and copolymers was measured according to A.S.T.M. Methods D-638 and D-759 at 300F using the molded tensile bars.
The following results in Table VII were observed.

TABLE VII
Mol. Wt. Mole R~tioTensile Strength Polymer (by GPC) A/Bat 300F, psi ::
Commercial30,000 Bis A 1,600 Polycarbonate Homopolymer Resin Example 3 33,800 0.08 ~ 2,200 Example 1428,700 0.18 5,100 '~ Control 1 17,456 0.91 2 Control 3 6,998 0.11 2 1 Same as above 2 Molded ten~ile bars of sufficient strength to perform the test could not be made due to the lower molecular weight of the polymer 17~766-F -18-, .
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' The invention is still further illustrated by the following creep resistance test.
The tensile creep property of the homopoly-carbonate of 4,4'-isopropylidenediphenol (homopolymer from Control 11) was measured by a method similar to and consistent with ASTM Method D-2990, at 2000 psi loading and at 80C. The results were compared to those obtained from the same measurement on the copolycarbonate from phenol-phthalein (A) and 4,4'-isopropylidenediphenol (B) (mole ratio A/B = 0.18; polymer from Example No. 14). Copoly-carbonates from Controls 1 and 3 could not be sujected to this test because specimens of sufficient strength to perform the test could not be molded due to the low molecular weight of these preparations. The results from these tests, shown in Figure 3 of the drawings, show that under these conditions the homopolymer exhibits "run-away" creep after about 5 to 10 hours whereas the copolymer was resistant to creep.
The following tests demonstrate the improved stress crack resistance of the copolycarbonates of this invention.
Molded specimens of the polymers (0.125 x 0.5 x 4.0~) were notched on opposite sides (0.25" radius-of-curvature) to provide a point in the specimen with a width of 0.35". The speCimens were then surrounded by special chambers, sealed on the bottom with a silicone grease or a gas-resistant sealer, then covered and mounted on an instrument for dead weight load testing. The instrument was arranged such that the specimen was holding a certain amount of weight (which created a certain stress in the polymer) and when the polymer "
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broke, the weights fell on a switch which shut off a timer thus giving the time-to-failure. Solvents were then added to the chamber by way of a syringe and weights were applied until the full load was in force.
The results shown in Table VIII were obtained at room temperature (about 22C) using n-heptane as the solvent.
TABLE VIII

Stress on Time-to-Failure, min., for various polymers SpecLmen, .
; psi Homopolymer Copolymer 1~ Copolymer 2~ Copolymer 3' ~; 10 3000 300 2400 -- 15,000 3500 32 60 300 1,380 1 Commercial homopolycarbonate of 4,4'-isopropylidenediphenol of weight average molecular weight 30,000 2 Copolycarbonate from 4,4'-isopropylidenediphenol (B) and phenolphthalein (A) with mole ratio of A/B = 0.08, from Example 3 (molecular weight = 35,300) 3 Same as 2 but A/B = 0.18, from Example 14 (molecular weight = 28,700) 4 Same as 2 but A/B = 0.31, from Example 8 (molecular weight = 30,508) . .
Improvements were also noted for such stress crack resistance in solvents such as gasoline and isopro-panol for copolycarbonatés of 4,4'-isopropylidenediphenol (B) and phenolphthalein (A) where the mole ratio of A/B
was greater than 0.08 and the weight average molecular weight, as determined by gel permeation chromatography, was greater than 25,000.
The control polymers and the examples used in the foregoing tests were prepared by two general procedures, the pyridine solution technique and the interfacial technique.

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, However, other known polymerization techniques can be used such as transesterification. Also, the following procedures can utilize known phosgene equivalents, such as the chloroformates of the diphenols, in place of phosgene.
It is noted that the polymers in the examples all had melt indexes in a range suitable for use as an injection molding resin by ASTM D1238-70, condition O.
The polymer of Control 9, Table IX had a melt index of zero when tested in this manner indicating the polymer would be very difficult, if not impossible, to injection mold and would not be useful as a commercial resin.
The general procedure for the preparation of phenolphthalein polycarbonates by the solution technique ; 15 is as follows:
; A glass reactor was placed in a water bath controlled to operate at about 25C. Methylene chloride was added and the reactor was purged with nitrogen.
Then, varying amounts of phenolphthalein, para bisphenol A, and para t-butyl phenol, as the chain ter-minator, was added to the reactor along with varying amounts of pyridine.
Phosgene gas was then added to the reactor at a `` variable rate of about 2.8 gms per minute to keep the reaction temperature in the range from 23-25C until an excess of phosgene had been added to the reactor.
The pyridine was then extracted with 3.25 molar hydrochloric acid and the methylene chloride solution } containing the polycarbonate was water-wa~hed twice, filtered and hexane was added to precipitate the poly-carbonate which was then recovered and dried.

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Table IX gives the amounts of reactants and the physical properties of the resultant polycarbonates.

TABLE IX
A/B Termin- Monomer Used MoleMoles ation (gms/moles)Mol. Wt.
Polymer Ratio Pyridine Mole ~* A B (by GPC) Control 4 1.00 8.82 4 477 5342 S 21,200 Control 5 1.00 8.82 3 477.5342.5 27,300 1.5 1.5 Control 6 1.00 8.82 2 477 5342 5 32,800 Control 7 1.00 8.82 1.5 477.5342.5 39,900 1.5 1.5 Control 8 1.50 8.82 2 572.9274.0 33,900 1.8 1.2 , 10 Control 12 0.24 1.58 0 93.75 31.25 75,000 ` 0.41 0.098 Example 1 0.08 13.28 2.6 120 1080 29,800 .377 4.731 Example 6 0.18 13.42 2.6 250 1000 32,200 ` ~.785 4.380 -Example 9 0.30 12.54 2.6 360 840 29,900 ~.131 3.679 Example 11 0.43 7.80 2 296 5 479 4 35,600 Example 12 0.43 8.82 2 289.5 479.4 33,200 0.9 2.1 * (based on total moles) A - phenolphthalein B - bisphenol A

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~06Z394 The interfacial process for the preparation of phenolphthalein polycarbonates is illustrated by the procedure set forth below for Example 5.
Example 5 320 gms of p-Bisphenol A, 80 gms phenolphthalein, and 1.0 gm of sodium sulfite are suspended in 1475 ml of water. In a 5 liter flask equipped with stirrer, thermo-meter, reflux condenser, and gas addition dip tube, oxygen is removed from the mixture by purging with nitrogen while agitating for 5 minutes. Then 180 ml of 35% sodium hydroxide solution are added, continuing the nitrogen purge and agitation for 5 minutes. At this point, with continued stirring and external cooling, are added 1150 ml of methylene chloride and 2.4 ml of triethyl amine. The contents are stirred for 5 minutes. Then gaseous phosgene was fed in at a rate of about 1.9 gms per minute, main-taining a reaction temperature of 25C. External cooling is necessary for good temperature control. Additions of 35~ sodium hydroxide are added intermittently during phosgenation until 213 gms of phosgene are added.
The intermittent additions of ml 35% NaOH/gms of phosgene are as follows:
(180 ml/95 gms), (70 ml/40 gms), (70 ml/31 gms) (70 ml/29 gms) and (40 ml/18 gms).
After phosgenation the reactants were allowed to ` stir and digest at 25C for 30 minutes. At this time stirring was stopped allowing the reactants to separate into a 2 phase system. The water layer was separated from the oil phase. The methylene chloride polymer solution was acidified with hydrochloric acid and diluted with 17~766-F -23-additional methylene chloride to a desired viscosity.
This solution was washed thoroughly with water, then transferred to a separatory funnel where it was allowed to stand for about 2 hours. Then the solution was filtered through dry diatomaceous earth to remove the last trace of water, then added to 3 volumes of hexane where the polymer precipitates out into a stringy fibrous precipitate. This firm dough-like material was chopped to desired particle size in a Waring blender containing - 10 H2O, filtered and vacuum dried.
Mol. wt. by GPC - 29,544 This polymer was injection molded resulting in ~a plastic with the following physical characteristics:
Melt Index 300C 4.96 gms/min Yield Tensile 9570 lbs/in2 % Elongation, mm 6.7 Heat Deflection 319F
Izod Notch Impact 13 8 ` By ASTM Method D-256 Color Index 5.4 Following essentially this procedure, the controls ard examplea in Table X may be prepared.

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TABLE X

A/B Mole Mol. Wt.
Polymar Ratio (by GPC) Control 2 0.08 19,247 Control 9 homopolymer 20,924 Control 10 homopolymer 25,381 Control 11 homopolymer 29,900 Example 2 0.08 31,400 Example 3 0.08 35,300 Example 4 0.08 34,000 Example 5 0.18 29,544 Example 7 0.238 38,813 Example 8 0.308 30,508 Example 10 0.308 34,335 : Example 13 0.08 27,800 :~ 15 Example 14 0.18 28,700 Example 15 0.238 33,046 A = phenolphthalein B = bisphenol A

~- ` The following controls 1 and 3 were run as , 20 exact duplicates of Examples 1 and 2 of U.S.P. 3,036,036 and the weight-average molecular weights determined by gel permeation chromatography (GPC).
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Control 1 (Example No. 1 of Patent 3,036,036) A sample of 3.3 parts by weight of 4,4'-isopropy-lidenediphenol bis (chloroformate) in 100 parts by volume of methylene chloride is added to 2.71 parts by weight of phenolphthalein, 1.46 parts by weight of sodium bicarbonate, 1.0 parts by volume of 5 percent aqueous solium hydroxide, 3 parts by volume of 3 percent benzyltrimethylammonium chloride and 80 ~arts by volume of water. The mixture containing a pink colored aqueous layer, is stirred for 1/2 hour with a high-speed mixer at room temperature resulting in a colorless emulsion. Stirring is continued for an additional hour during which time 5 percent aqueous sodium hydroxide is added dropwise to maintain the color of the reaction mixture pink. On standing overnight at room temperature the mixture separates into two layers.
The supernatant aqueous layer is decanted and the methylene chloride portion is then extracted with slightly alkaline water. The methylene chloride portion is then added dropwise to 1000 parts by volume of 95 percent ethyl alcohol which is constantly stirred. A fine white precipitate thus formed is recovered by filtration and is further purified by washing and precipitation from solution ' and then dried. Analysis of this precipitate provided the following results:
Mol. wt. by GPC 17,452 Relative Viscosity (0.5~ dioxane) 25C - 1.128 $ Centipoise The molded polymer results in a weak brittle plastic. A clear fiber may be drawn from a melt of the polymer.

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Control 3 (Example 2 of Patent 3,036,036) To 1. 55 parts by weight of 4,4'-isopropylidene-diphenol, 1.43 parts by weight of sodium bicarbonate, 0.54 parts by weight of phenolphthalein, 10 parts by volume of

5 percent aqueous sodium hydroxide, and 3 parts by volume of 3 percent aqueous benzyltrimethylammonium chloride dissolved in 85 parts by volume of water, is added 2.97 parts by weight of 4,4'-isopropylidenediphenol bis (chloroformate) dissolved in 85 parts by volume of methy-lene chloride. The mixture is stirred vigorously for one hour during which time 5 percent aqueous sodium hydroxide is added dropwise to maintain the color of the reaction mixture pink. After standing over night at room temperature the mixture separates into two layers. The supernatant aqueous layer is decanted and the methylene chloride portion is extracted with water. The methylene chloride portion is then added dropwise to 500 parts by volume of 95 percent ethyl alcohol and a fine white precipitate forms.
The polymer is recovered by filtration followed by vacuum drying. Analysis of the polymer provided the following results:
Mol. wt. by GPC 6,998 Relative Viscosity (0.5% dioxane) - 1.104 Centipoise Molding of the polymer resulted in a weak, brittle ~ 25 plastic. A clear fiber may be drawn from a melt of the ~; -s polymer.

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Claims (7)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A thermoplastic polycarbonate resin con-sisting of a chain of divalent phenolphthalein radicals mixed with divalent dihydroxyaromatic radicals in the mole ratio range of phenolphthalein to dihydroxyaromatic compound from 0.05 to 0.7 wherein the phenolphthalein and dihydroxyaromatic radicals are linearly connected by carbonate ester groups, said resin having a weight average molecular weight from 25,000 to 60,000 as determined by gel permeation chromatography.

2. The polycarbonate resin as set forth in Claim 1, wherein the mole ratio range is from about 0.12 to about 0.43.

3. The polycarbonate resin as set forth in Claim 1, wherein the mole ratio range is from about 0.18 to about 0.33.

4. The polycarbonate resin as set forth in Claim 1, wherein the resin has a molecular weight range from about 30,000 to about 60,000.

5. The polycarbonate resin as set forth in Claim 1, wherein the dihydroxyaromatic radicals are derived by, removing the hydroxyl hydrogens from 4,4'-isopropylidene-diphenol.

6. The polycarbonate resin as set forth in Claim 5, wherein the mole ratio range is from about 0.12 to about 0.43.

7. The polycarbonate resin as set forth in Claim 5, wherein the mole ratio range is from about 0.18 to about 0.33.