US 4,880,855 AGrant

Enhancing Color Stability to Sterilizing Radiation of Polymer Compositions

Issue Date:1989-11-14

•9 Claims

Abstract

Compounds having defined sulfone functional groups are described which color stabilize aromatic carbonate polymers or blends therewith upon exposure to sterilizing radiation.

Metadata

Assignee

General Electric Company

Inventors

Linda H. Nelson
Roger W. Avakian
Arnold Factor

Application Information

Application Number:US 1366092

Filing Date:1987-12-22

Priority Date:1984-02-10

Art Unit:153

Classifications

IPC:

C08R 541

Field of Search:

52252452359;79;163167;170;171136

Patent Drawings

This patent does not have any drawings.

Description

Description of Specific Embodiments

Further illustration of this invention is set forth in the following examples. There is no intention to limit the scope of the invention to merely what is shown.

The following resins were used in the formulations of the examples:

Polycarbonate - LEXAN.RTM. 145 resin, poly(bisphenol-A carbonate), General Electric Company (contains 0.06% by weight of a conventional phosphite stabilizer).

Poly(ester-carbonate) - an ester content of 75% mole % and being 93 mole % isophthalate and 7 mole % terephthalate.

Polycarbonate/polyester blend - 80 weight parts polycarbonate with 20 weight parts KODAR A150 resin, Eastman Kodak Company, poly(1,4-cyclohexanedimethanolterephthalate-co-isophthalate) and a phosphorous acid stabilizer.

Unless otherwise noted, the formulations containing 100 weight parts of the indicated resin or blend were extruded on a sterling single screw (13/4") extruder at a melt temperature of Tl. Test plaques 1/8" in thickness were injection molded on a 3 oz. Van Dorn using a T2 melt set temperature, a T3 mold cavity temperature, and a 10/20 cycle time. Tl, T2, and T3 were 5 set according to the resin or blend used:

The samples were irradiated by one of the following methods:

Gamma Irradiation - samples were exposed to a Co.sup.60 source on a continuous conveyor system, dosimetry was monitored with a calibrated NBS, radiochromic, nylon dosimeter and different Co60 sources were used.

Electron Beam Irradiation - samples irradiated on one side in air using a linear cathode electron beam system, 5 Mrad dose, 20 ft/min line speed, 5 mA beam current, 200 KV terminal voltage, dosimetry monitored with a calibrated NBS, radiochromic, nylon dosimeter.

Unless otherwise noted, testing of the samples has been conducted with gamma radiation and yellowness index, Y.I., measured on a Gardner colorimeter in accordance with ASTM D1925 both before and after radiation. The less change in Y.I. upon irradiation, the more effective the stabilizer.

Examples 107-118

The following formulations were extruded at from 271.degree. to 299.degree. C. and injection molded into test plaques 1/8" in thickness using a melt temperature of from 271.degree. to 288.degree. C. and a mold temperature of from 49.degree. to 82.degree. C. Measurementof yellowness index was made on a Pacific-Scientific Spectrogard II unit in accordance with ASTM D1925.

Example 121

The following composition was extended from 260.degree. to 316.degree. C. and injection molded into test plaques 1/8" in thickness using a melt temperature of from 260.degree. to 304.degree. C. Measurement of yellowness index was made on a Pacific Scientific Spectrogard II unit in accordance with ASTM D-1925.

Examples 129-131

The following formulations were molded in accordance with the conditions of Examples 107-118:

Claims

What is claimed is:

1. A composition comprising an aromatic carbonate polymer in admixture with an effective amount of a stabilizing sulfone (--SO.sub.2) compound effective to inhibit yellowing upon exposure to sterilizing radiation, wherein said stabilizing sulfone compound has the general formula R.sup.5 --SO.sub.2 --R.sup.6, R.sup.5 and R.sup.6 are the same or different, and R.sup.5 and R.sup.6 are selected from the group consisting of alkyl and aryl.

2. The composition of claim 1 wherein at least one of R.sup.5 and R.sup.6 of said stabilizing compound is a substituted or unsubstituted benzyl group.

3. The composition of claim 1 wherein said aromatic carbonate polymer is a poly(bisphenol-A) carbonate.

4. The composition of claim 1 wherein said aromatic carbonate polymer is a poly(ester-carbonate).

5. The composition of claim 1 which further comprises a polyester resin.

6. The composition of claim 1 which contains 0.01-5.0 weight parts stabilizing compound per 100 weight parts polymer.

7. The composition of claim 1 which contains 0.01-0.50 weight parts stabilizing compound per 100 weight parts polymer.

8. The composition of claim 1 which comprises a plurality of stabilizing compounds.

9. The composition of claim 1 which further comprises a polyestercarbonate resin.

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