TRANSPARENT BRANCHED POLYCARBONATE

Abstract

A method for preparing a modified polycarbonate comprising i) providing a polycarbonate prepared by the melt transesterification of a bisphenol and a diaryl carbonate preferably having a Fries branching level of from 750 to 2000 ppm, ii) combining said polycarbonate and from 0.10-0.75 wt. %, based on the amount of polycarbonate, of a modifier, iii) reacting said modifier and said polycarbonate in molten state at a temperature of from 250-300 C. and a reaction time of at least 30 seconds so as to form the modified polycarbonate, wherein said modifier is a styrene-(meth)acrylate copolymer containing glycidyl groups and having i) from 250 to 500 gram epoxy groups per mol and ii) a weight average molecular weight of from 3000 to 8500 g/mol, and wherein said modified polycarbonate has a transmittance of at least 85% and a haze of at most 5% as determined in accordance with ASTM D1003-13 on an injection moulded sheet having a thickness of 3 mm.

Claims

1. A method for preparing a modified polycarbonate comprising: providing a polycarbonate prepared by the melt transesterification of a bisphenol and a diaryl carbonate, combining said polycarbonate and from 0.10-0.75 wt. %, based on the amount of polycarbonate, of a modifier, reacting said modifier and said polycarbonate in a molten state at a temperature of from 250-300 C. and a reaction time of at least 30 seconds so as to form the modified polycarbonate, wherein said modifier is a styrene-(meth)acrylate copolymer containing glycidyl groups and having from 250 to 500 gram epoxy groups per mol, and wherein said modified polycarbonate has a transmittance of at least 85% and a haze of at most 5% as determined in accordance with ASTM D1003-13 on an injection moulded sheet having a thickness of 3 mm.

2. The method of claim 1 wherein the amount of modifier is from 0.10-0.65 wt. %.

3. The method of claim 1 further comprising cooling the modified polycarbonate to a temperature below 100 C. to obtain the modified polycarbonate in a solid form.

4. The method of claim 1 wherein the polycarbonate has a melt flow index of from 3.0-12 g/10 min as determined in accordance with ASTM D 1238 (1.2 kg, 300 C.).

5. The method of claim 1 wherein the tan of the modified polycarbonate is at most 90% of the tan of the polycarbonate, wherein tan =G/G being the ratio of the loss modulus (G) and the storage modulus (G) and determined at 0.1 rad/s and 280 C. using a plate rheology measurement.

6. The method of claim 1 wherein tan of the modified polycarbonate is at most 15.

7. The method of claim 1 wherein the method is a continuous method.

8. A modified polycarbonate obtained by the method of claim 1.

9. The modified polycarbonate of claim 8 having an Izod Notched impact strength of at least 60 kJ/m.sup.2 as determined in accordance with ISO 180/A on a sample having a thickness of 3 mm and at a temperature of 23 C.

10. The modified polycarbonate of claim 8 having an R* value, as defined herein of from 2.2-4.2.

11. An article comprising the modified polycarbonate of claim 8.

12. The article of claim 11 wherein the article is a hollow container, a single layer sheet, a multi-wall sheet or an extruded profile.

13. The article of claim 11, wherein the article is a hollow container formed by blow molding.

14. The method of claim 1, further comprising extruding the modified polycarbonate to form extruded profiles, single layer sheets or multi-wall sheets.

Description

EXAMPLES

[0061] Samples of modified polycarbonate were prepared by modification of polycarbonate using a co-rotating twin-screw extruder with an L/D of about 41 and a screw diameter of 25 mm. The temperature ranged from 40 C. at the feed zone to 290 C. at the die. The torque was maintained in a range of from 60-70% of the maximum torque of the extruder equipment.

[0062] The following materials were used:

[0063] PC-1: Polycarbonate produced via the melt transesterification of diphenyl carbonate and bisphenol A, and having a MFR of 6 g/10 min and an amount of Fries branching of 1900 ppm. PC 1 is unquenched, meaning that after the polymerisation the catalyst is not deactivated.

[0064] PC-2: Polycarbonate produced via the melt transesterification of diphenyl carbonate and bisphenol A, and having a MFR of 10 g/10 min. PC 2 is unquenched, meaning that after the polymerisation the catalyst is not deactivated.

[0065] PC-3: Polycarbonate produced via the melt transesterification of diphenyl carbonate and bisphenol A, and having a MFR of 6 g/10 min and an amount of Fries branching of 900 ppm. PC 3 is quenched, meaning that after the polymerisation the catalyst is deactivated by addition of a suitable amount of butyl-tosylate.

[0066] Mod1: Polymeric chain extender Joncryl ADR-4368 commercially available from BASF and being a styrene-(meth)acrylate copolymer containing glycidyl groups having a Mw of 6800, a Tg of 54 C. and an epoxy equivalent weight of 285 g/mol, corresponding to about 3500 meq/kg of epoxy groups. The number of epoxy groups per unit chain length is about 23.

[0067] Mod2: Polymeric chain extender Joncryl ADR-4400 commercially available from BASF and being a styrene-(meth)acrylate copolymer containing glycidyl groups having a Mw of 7100, a Tg of 65 C. and an epoxy equivalent weight of 485 g/mol, corresponding to about 2060 meq/kg of epoxy groups. The number of epoxy groups per unit chain length is about 15.

[0068] Mod3: Polymeric chain extender Joncryl ADR-4300 commercially available from BASF and being a styrene-(meth)acrylate copolymer containing glycidyl groups having a Mw of 5500, a Tg of 56 C. and an epoxy equivalent weight of 445 g/mol, corresponding to about 2250 meq/kg of epoxy groups. The number of epoxy groups per unit chain length is about 12.

[0069] Table 1 provides an overview of the experimental data based on modifier 1 (Mod1).

TABLE-US-00001 TABLE 1 CE1 E1 E2 E3 CE2 CE3 CE4 PC1 [wt. %] 100 99.90 99.75 00.50 99.25 99.00 PC2 [wt. %] 100 Mod1 [wt. %] 0 0.10 0.25 0.5 0.75 1 0 Tan @ 0.1 rad/s 99.7 30.5 12 10.7 5.7 4 42.6 MFR [g/10 min] 6.0 5.9 5.6 4.5 10 Haze [%] 1.75 0.8 1.1 2 60.2 48.8 Transmission [%] 90.2 90.6 90.7 90.7 89 88 NA Notched impact 69 67 67 66 55 57 NA strength [KJ/m.sup.2] R* 2.2 2.5 3.3 3.7 7.9 NA NA

[0070] From this table it is clear that the optical properties unexpectedly deteriorate at modifier loading levels of about 0.75%. Similarly the impact strength at loading levels of 0.75% reduces. The melt flow rate (MFR) of modified polycarbonate with load levels of 0.75% or higher could not be determined. The inventors believe this is indicative for undesired levels branching or possibly even cross-linking of the polycarbonate chains. Based on the experimental data the present inventors believe that modifier loading levels of from 0.10 to 0.65% result in modified polycarbonates with acceptable properties.

[0071] Further experiments were carried out with PC-2 using both modifier 1 as modifier 3. Table 2 provides an overview of these experiments.

TABLE-US-00002 TABLE 2 CE5 E4 E5 E6 E7 E8 E9 PC2 [wt. %] 100 99.90 99.75 99.50 99.90 99.75 99.50 Mod1 [wt. %] 0.10 0.25 0.50 Mod3 [wt. %] 0.10 0.25 0.50 Tan @ 0.1 rad/s 29.69 NA 21.35 15.08 18.12 16.45 7.89 Haze [%] 0.66 0.81 1.15 0.89 0.69 0.72 0.69 Transmission [%] 91.3 90.8 90.4 90.9 91.1 90.9 91.1

[0072] The Table 2 shows that both Mod1 as Mod2 result in good optical properties.

[0073] Experiments with PC-3 were carried out and the results are shown in Table 3 below.

TABLE-US-00003 TABLE 3 CE6 E10 E11 E12 CE7 CE8 E13 CE9 CE10 PC3 [wt. %] 100 99.90 99.75 99.50 99.25 99.0 99.50 99.25 99.0 Mod1 [wt. %] 0.10 0.25 0.50 0.75 1.0 Mod2 [wt. %] 0.50 0.75 1.0 Tan @ 0.1 rad/s 76 23 21 12 4.4 1.2 12 11 3.5 MFR [g/10 min] 6.0 6.3 5.4 3.2 1.6 NA 4.3 3 1.2 Haze [%] 0.5 0.5 0.5 1.5 10 76 0.8 3.7 36 Transmission [%] 91.3 91.1 91.1 91.1 91.1 89.1 91.2 91.2 90.5 Notched impact 77 78 75.3 76.4 70.6 73 74.8 74.5 74.5 strength [KJ/m.sup.2] R* 1.7 1.7 2.0 2.7 5.6 8.6 2.7 2.9 3.7

[0074] From Table 3 the present inventors conclude that the use of the modifier according to the invention is suitable for modifying both quenched as unquenched polycarbonate prepared using the melt transesterification process. Similar results are obtained in haze, transmission and impact behaviour and the R* value indicates that the material is suitable for blow moulding applications.

[0075] In general, the invention may alternately comprise, consist of, or consist essentially of, any appropriate components herein disclosed. The invention may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objectives of the present invention. The endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of less than or equal to 25 wt %, or 5 wt % to 20 wt %, is inclusive of the endpoints and all intermediate values of the ranges of 5 wt % to 25 wt %, etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group. A combination is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms a and an and the herein do not denote a limitation of quantity, and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Or means and/or unless clearly indicated otherwise by context.

[0076] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference. Application EP Application No. 18175713.9, filed on Jun. 4, 2018, is incorporated herein in its entirety.

[0077] Unless specified to the contrary herein, all test standards are the most recent standard in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.