Use of polycarbonate for the manufacture of hollow containers

Abstract

The present invention relates to the use of an aromatic polycarbonate prepared by the transesterification of a bisphenol and a diaryl carbonate and having a viscosity average molecular weight, Mv, of from 22000 to 32000 g/mol, a polydispersity, defined as Mw/Mn, of from 1.8-3.2, a melt-flow index of from 3.0-10 g/10 min as determined in accordance with ASTM D 1238 (1.2 kg, 300° C.), an amount of Fries branching of from 750 to 2500 ppm, for the manufacture of bottles having a volume of at least 15 liter by means of an injection blow moulding or an extrusion blow moulding process.

Claims

1. A bottle, comprising: a volume of at least 15 liter, and obtained via injection blow moulding or extrusion blow moulding a polycarbonate prepared by the transesterification of a bisphenol and a diaryl carbonate, said polycarbonate having: a viscosity average molecular weight, Mv, of from 22000 to 32000 g/mol, a polydispersity, defined as Mw/Mn, of from 1.8-3.2, a melt-flow index of from 3.0-10 g/10 min as determined in accordance with ASTM D 1238 (1.2) kg, 300° C.), and an amount of Fries branching of from 750 to 2500 ppm.

2. The bottle of claim 1 having a volume of at least 18.9 liters (5 US gallon).

3. The bottle of claim 1 wherein the polycarbonate further contains from 20-200 ppm, by weight based on the weight of the polycarbonate of a zeolite suitable for the removal of aromatic molecules.

4. The bottle of claim 1, wherein the polydispersity is from 2.0-3.0.

5. The bottle of claim 4, wherein the polycarbonate further contains from 20-200 ppm, by weight based on the weight of the polycarbonate of a zeolite suitable for the removal of aromatic molecules.

6. The bottle of claim 5, wherein the polycarbonate contains from 70-150 ppm of the zeolite.

7. A method for the manufacture of a bottle having a volume of at least 15 liters, comprising: melt transesterification of a bisphenol and a diaryl carbonate to form a polycarbonate having a viscosity average molecular weight, Mv, of from 22000 to 32000 g/mol, a polydispersity, defined as Mw/Mn, of from 1.8-3.2 and a melt-flow index of from 3.0-10 g/10 min as determined in accordance with ASTM D 1238 (1.2) kg, 300° C.), optionally adding stabilisers and/or a dye to said polycarbonate, and injection blow moulding or extrusion blow moulding said polycarbonate to form said bottle.

8. The method of claim 7 wherein the bottle has a volume of at least 18.9 liters (5 US gallon).

9. The method of claim 7, further comprising adding from 20-200 ppm by weight based on the weight of the polycarbonate of a zeolite suitable for the removal of aromatic molecules prior to forming of the bottle.

10. The method of claim 9, comprising adding from 70-150 ppm of the zeolite prior to forming of the bottle.

11. The method of claim 7, comprising adding stabilisers and/or a dye to said polycarbonate, and wherein the polydispersity is from 2.0-3.0.

12. The method of claim 11, wherein the bottle has a volume of at least 18.9 liters (5 US gallon).

Description

EXAMPLES

(1) A polycarbonate was manufactured in accordance with the melt transesterification method using BPA and DPC as the starting materials.

(2) A comparative example consists of a branched polycarbonate manufactured in accordance with the interfacial process. Such polycarbonate is known not have any Fries branching.

(3) The polycarbonates used in the experiments had the following properties

(4) TABLE-US-00001 TABLE 1 Example Comparative Example Fries 1729 [ppm] [—] branching Mn 10828 [g/mol] 8513 [g/mol] Mw 26753 [g/mol] 31724 [g/mol] Mw/Mn 2.47 [—] 3.73 [—] Mv 24043 [g/mol] 27101 [g/mol] MI 6.0 [g/10 min] 2.6 [g/10 min] (Mn, Mw and Mv being determined using TDA-GPC)

(5) The materials as specified in the Table 1 above were used in experiments to manufacture bottles by an extrusion blow molding process. The volume of the bottles was 5 US gallons (18.9 liter). The equipment comprised a single screw extruder an extrusion die and a mold operated at the settings indicated in Table 2 below.

(6) TABLE-US-00002 TABLE 2 Extruder Temp (° C.) Die Temp (° C.) Mold Temp (° C.) Zone CE EX Zone CE EX CE EX Cyl 1 248 240 Die Head 236 210 75 75 Cyl 2 235 220 Cyl 3 242 213 Die 1 220 201 Cyl 4 242 213 Cyl 5 240 214 Die 2 220 203 Adaptor 236 210 Neck 228 210 Die 3 236 205

(7) Bottles without any visual defects could be produced from both comparative polycarbonate as the polycarbonate according to the invention. Both bottles also passed the drop test. The Table 2 shows that, compared to the Comparative Example, the polycarbonate as defined herein not only allows good quality bottles to be produced, but also a lower energy consumption as a result of the lower temperature settings of the extruder and die.

(8) The materials as specified in the Table 1 above were also used in experiments to manufacture bottles by an injection stretch blow molding process (ISBM). The volume of the bottles was 5 US gallon (18.9 liter). The equipment used was a commercially available injection stretch blow molding machine comprising an extruder having five heating zones in the barrel, three hot zones in the hot runner and seven zones in the preheater (also referred to as hot pot). The hot pot is used to condition the preform prepared in the hot runner prior for said preform to be blown to its final bottle shape. Injection stretch blow molding equipment is known to a skilled person.

(9) The settings in the ISBM process were as follows, wherein M/C refers to the molding conditions.

(10) TABLE-US-00003 TABLE 3a ISBM settings for PC according to the invention (EX) Zones M/C (° C.) Hot Runner (° C.) Hot Pot (° C.) 1 260 290 173 2 260 285 142 3 270 335 140 4 260 140 5 290 148 6 166 7 240

(11) TABLE-US-00004 TABLE 3b ISBM settings for PC according to the invention (EX) Zones M/C (° C.) Hot Runner (° C.) Hot Pot (° C.) 1 285 290 200 2 285 290 185 3 290 335 175 4 285 160 5 290 160 6 170 7 240

(12) From comparing Tables 3a and 3b again it becomes clear that the polycarbonate according to the invention allows for less energy consumption while the experiments resulted in good quality bottles for both the experiment as the comparative experiment. Both bottles passed the drop test.

(13) Zeolite Addition

(14) Polycarbonates with and without zeolite were analysed on presence of volatiles using head space GCMS techniques performed at a temperature of 200° C. The zeolite was ZEOflair® 810 which was added in an amount of 100 ppm. The surface area's of the peaks relating to phenol, 2,4-di-tert-butylphenol and diphenyl-carbonate were determined. It was found that under the given test conditions the total surface area was reduced with 19% indicating that the zeolite captured the said molecules and prevented the same from being released from the material upon performance of the GCMS headspace test.