By means of ionizing radiation sterilizable moulded parts made from polycarbonate

Abstract

The invention relates to a thermoplastic composition comprising A) aromatic polycarbonate, B) 0.1 to 5 wt.-% one or more polyether polyols and C) 0.01 to 0.30 wt.-% 3,3′-thiodipropionic acid. The invention also relates to medical technology products or parts of medical technology products consisting of such compositions as well as to a process for sterilization of such moulded parts by means of irradiation. The polycarbonate compositions according to the invention show significantly less yellowing after irradiation than known compositions and still have good mechanical properties.

Claims

1. A thermoplastic composition consisting of A) aromatic polycarbonate, B) 0.1 to 5 wt.-% one or more polyether polyols, C) 0.01 to 0.30 wt.-% 3,3′-thiodipropionic acid, and D) up to 30 wt.-% one or more further additives selected from the group consisting of flame retardants, antidripping agents, impact modifiers, fillers, antistats, colouring agents, pigments, thermal stabilizers different from components B and C, lubricants and/or demoulding agents, UV absorbers, IR absorbers, hydrolysis stabilizers and/or compatibilizer.

2. The thermoplastic composition according to claim 1, wherein the composition comprises 0.05 to 0.30 wt.-% 3,3′-thiodipropionic acid.

3. The thermoplastic composition according to claim 1, wherein the aromatic polycarbonate comprises bisphenol A-based polycarbonate.

4. The thermoplastic composition according to claim 3, wherein the composition does not comprise any other polycarbonate than bisphenol A-based polycarbonate.

5. Thermoplastic composition according to claim 1, comprising at least 95 wt.-% aromatic polycarbonate.

6. The thermoplastic composition according to claim 1, wherein the amount of polyether polyol is 0.1 to 2 wt.-%.

7. The thermoplastic composition according to claim 1, wherein the amount of 3,3′-thiodipropionic acid is 0.05 to 0.25 wt.-%.

8. The thermoplastic composition according to claim 1, consisting of A) 69.85 wt.-% to 98.5 wt.-% aromatic polycarbonate, B) 0.1 wt.-% to 2 wt.-% polyether polyol, C) 0.05 wt.-% to 0.25 wt.-% 3,3 ‘-thiodipropionic acid and D) up to 30 wt.-% one or more further additives selected from the group consisting of flame retardants, antidripping agents, impact modifiers, fillers, antistats, colouring agents, pigments, thermal stabilizers different from components B and C, lubricants, demoulding agents, UV absorbers, IR absorbers, hydrolysis stabilizers and/or compatibilizer.

9. The thermoplastic composition according to claim 1, wherein the polyether polyol is formed from repeating propylene oxide units with propylene glycol as starter molecule and has an OH number within a range of from 50 to 70 mg KOH/g determined according to DIN 53240-3:2016-03.

10. A process for sterilization of moulded parts, wherein a moulded part consisting of or comprising an area consisting of a thermoplastic composition according to claim 1 is exposed to β-radiation and/or γ-radiation with a dose of at least 20 kGy.

11. The process according to claim 10, wherein the irradiation is conducted in an oxygen atmosphere or in oxygen reduced atmosphere.

12. The process according to claim 10, wherein the moulded part is contained in a closed pouch during irradiation.

13. A medical technology product or part of a medical technology product comprising a composition according to claim 1.

14. The medical technology product according to claim 13, wherein the part is a part of a dialyzer, a part of an oxygenator, a tubing connector, a miscellaneous connector, an element for a blood pump, an infusion valve connector, an injection syringe, an intravenous access component, a surgical instrument, or a two-way valve or selector valve.

Description

EXAMPLES

(1) Components:

(2) A1: Makrolon® 2508 from Covestro Deutschland AG. Linear polycarbonate based on bisphenol A having a melt volume flow rate MVR of 15 cm.sup.3/10 min (according to DIN EN ISO 1133-1:2012-03), at a test temperature of 300° C. and load 1.2 kg.

(3) B1: Multranol 3600 DHP from Lanxess AG, Germany. Alpha, omega-bis(tetrahydro-2H-pyran-2-yl)-poly[oxy(methyl-1,2-ethanediyl)]. Polyether polyol.

(4) B2: Desmophen® 3600 Z from Covestro Deutschland AG. Bifunctional polyether polyol, based on propylene oxide with propylene glycol as starter. OH number: 56 mg KOH/g. Determined according to DIN 53240-3:2016-03. Most of the hydroxyl end groups are secondary hydroxyl end groups.

(5) M.sub.n=2,000 g/mol, determined as described before.

(6) C: 3,3′-thiodipropionic acid from Dr. Spiess Chemische Fabrik GmbH.

(7) D1: pentaerythrityl tetrakis(3-laurylthiopropionate). Songnox® 4120 from Songwon International AG, Switzerland.

(8) D2: mixture of colouring agents.

(9) Procedure:

(10) Laminate pouches (aluminium laminated) for irradiation-sterilization (OPA/Al/PE) from Sudpack Medica, Germany, size: length 24.5 cm*width 15.0 cm, were used. (OPA is a biaxially stretched polyamide film). As oxygen scavengers, those from 02 Zero, UK, were used. For irradiation-sterilization under O.sub.2-reduced atmosphere, one FMP (colour sample plate) and 5 pieces oxygen scavenger (50 cc intake capacity) were put into a laminate pouch which was then sealed. For irradiation-sterilization under O.sub.2-atmosphere, the FMP alone was sealed in a pouch.

(11) For all examples, FMP with a thickness of 4 mm were used. The compounds according to the examples were produced on an extruder ZE 25 of the company Berstorff with a throughput of 10 kg/h and a rotational speed of 50/min and a temperature of 270° C. The colour sample plates were injection molded on an Arburg ALLROUNDER injection molding machine. Process temperature was 280° C. during injection molding and the mold temperature was 80° C.

(12) As “relaxation time”, which the sample had for decoloration (loss of colour) after irradiation, a period of >21 days was used. This period was chosen, as at first, bleaching/decoloration happens slowly, but after a certain period, no further decoloration due to temporary colour centres takes place. Use of the light-proof, aluminium-laminated packagings has an influence on decoloration, as radiation in the VIS range speeds up decoloration.

(13) The irradiation experiments were conducted with β- as well as with γ-radiation with different doses according to DIN EN ISO 11137-1:2015:11. In principle, there is no difference in decoloration of the material after irradiation with β- or γ-radiation.

(14) Radiation used: 1) β-radiation (generation in electron accelerator 10 MeV): high dose rate and limited penetration depth.fwdarw.duration of sterilization process: few seconds 2) γ-radiation (generation by means of Co.sup.60-source): very high penetration depth and relatively low dose rate.fwdarw.duration of sterilization process: several hours until the intended dose was reached. This was followed by means of a dosimeter.

(15) In case of all compositions according to the invention, no significant plaque formation after irradiation was detectable.

(16) Melt volume flow rate (MVR) was determined as per DIN EN ISO 1133-1:2012-03 (test temperature 300° C., mass 1.2 kg) with a Zwick 4106 apparatus from Zwick Roell after 4 minutes.

(17) Determination of the IMVR-value was made according to DIN EN ISO 1133-1:2012-03 (test temperature 300° C., mass 1.2 kg) with a Zwick 4106 apparatus from Zwick Roell after 19 min.

(18) The Yellowness Index (Y.I.) was determined according to ASTM E 313-15e1 (2015-01-01, observer: 100/illuminant: D65) with sample sheets having a wall thickness of 4 mm measured with a Hunter UltraScanPro device. The difference ΔY.I. between the value 21 days after irradiation and before radiation was formed.

(19) TABLE-US-00001 TABLE 1 β-sterilization 50 kGy under O.sub.2-reduced atmosphere 1V 2V 3 4 5 6V 7V 8V 9V wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% A1 ≥99.99 99.249 99.199 99.149 98.999 98.749 98.499 99.149 98.499 B1 B2 0.75 0.75 0.75 0.75 0.75 0.75 0.75 0.75 C 0.05 0.1 0.25 0.5 0.75 D1 0.1 0.75 D2 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 properties MVR 17.5 18.2 20.2 38.8 51.6 IMVR 19.4 21.6 26.3 n.d. n.d. ΔYI 53.14 20.30 13.62 12.40 11.73 10.17 10.98 16.81 14.86 (After at least 21 days relaxation-before irradiation) n.d.: not determinable V: means comparison example Unstabilized polycarbonate compositions (1V) show a strong yellowing after radiation with β-radiation. The addition of stabilizers in the form of polyether polyols (2V) already effects a significant reduction of yellowing, but still not satisfying. Already as low amounts as 0.05 wt.-% additional 3,3′-thiodipropionic acid (example 3) effect a remarkable reduction of yellowing, wherein the addition of larger amounts of 3,3′-thiodipropionic acid (examples 4, 5) brings a further improvement. However, even larger amounts, e.g. 0.5 wt.-% und 0.75 wt.-% (6V, 7V) of added 3,3′-thiodipropionic acid lead to such high melt volume rates even before irradiation that processing of such compositions is no longer possible. Known stabilizer pentaerythrityl tetrakis(3-laurylthiopropionate) effects a higher increase in yellowing compared to 3,3′-thidipropionic acid (8V, 9V) compared with examples 4 and 7V.

(20) TABLE-US-00002 TABLE 2a γ-sterilization 30 kGy under O.sub.2 atmosphere 10V 11V 12 13 14 15V 16V 17V 18 19 20 wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% A1 ≥99.99 99.249 99.199 99.149 98.999 98.749 98.499 99.249 B1 0.75 0.75 0.75 0.75 B2 0.75 0.75 0.75 0.75 0.75 0.75 C 0.05 0.1 0.25 0.5 0.75 0.05 0.1 0.25 D2 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 Properties MVR 17.5 18.2 20.2 38.8 51.6 18.3 18.5 19.6 IMVR 19.4 21.6 26.3 n.d. n.d. 20.5 22.2 26.5 ΔYI 16.71 11.04 8.25 6.88 6.64 7.49 8.50 8.88 7.72 6.69 5.65 (After at least 21 days relaxation-before irradiation) n.d.: not determinable V: means comparison example Also after irradiation with γ-radiation, moulded parts produced from unstabilized polycarbonate compositions (10V) exhibit a significant yellowing, which can already be remarkably reduced by the addition of a polyether polyol (11V, 17V). A further, significant reduction of yellowing can be achieved by the addition of 3,3′-thiodipropionic acid (examples 12-14, 18-20), wherein for amounts of 0.5 wt.-% respectively 0.75 wt.-% (15V, 16V) the melt volume rates are that high that a good processability is not given anymore.

(21) TABLE-US-00003 TABLE 2b γ-sterilization 30 kGy under O.sub.2 atmosphere 21V 22V 23V 24V 25V 26V 27V wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% wt.-% A1 ≥99.99 99.249 99.149 98.499 99.249 99.249 98.499 B1 0.75 0.75 0.75 B2 0.75 0.75 0.75 C D1 0.1 0.75 0.1 0.75 D2 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 ≤0.001 Properties ΔYI 16.71 11.04 11.38 10.51 8.88 10.48 9.64 (After at least 21 days relaxation-before irradiation) The combination of a polyether polyol with a conventional stabilizer, Songnox 4120, effects a reduction of yellowing after irradiation (23V, 24V respectively 26V, 27V compared to 21V or 22V), but the effect is not so pronounced than with the combination of 3,3′thiodipropionic acid (examples 19, respectively 13).