Radiation sterilizable composition and articles made therefrom

Claim 2

An improved radiation sterilizable composition of the type comprising (a) a semi-crystalline polymer having a narrow molecular weight distribution; and an effective, radiation stabilizing amount of (b) a radiochromic hindered phenolic stabilizer, said improvement comprising using as said polymer a controlled-rheology polypropylene having a melt flow of greater than about 5 and including in said composition (c) a blue compound in an amount sufficient to form in the composition a green color by interaction with said radiochromic hindered phenolic stabilizer after said composition has been subjected to a sterilizing dose of gamma irradiation.

Claim 3

A composition as defined in claim 1 wherein said radiochromic hindered phenolic stabilizer comprises from about 0.01 to 1 part by weight per 100 parts by weight of said polymer.

Claim 4

A composition as defined in claim 2 wherein said radiochromic hindered phenolic stabilizer comprises from about 0.1 to about 0.3 parts by weight per 100 parts by weight of said polymer.

Claim 5

A composition as defined in claim 1 wherein said blue compound comprises from about 1 to about 13 parts by weight per 10 6 parts by weight of said polymer.

Claim 6

A composition as defined in claim 4 wherein said blue compound comprises from about 4 to about 8 parts by weight per 10 6 parts by weight of said polymer.

Claim 7

A composition as defined in claim 1 which optionally includes additives selected from: (d) an effective amount of co-stabilizer for (b) of an organic thioester or thioether; (e) an effective amount of an organic ultraviolet radiation stabilizer for said composition; (f) a mixture of (d) and (e).

Claim 8

A composition as defined in claim 1 wherein said polypropylene is a controlled rheology polypropylene.

Claim 9

A composition as defined in claim 7 wherein said controlled rheology polypropylene had, initially, a melt flow of below about 5.

Claim 10

A composition as defined in claim 8 wherein said polypropylene had, initially, a melt flow in the range of 0.01 to 1.

Claim 11

A composition as defined in claim 7 wherein said polypropylene has a final melt flow of between about 5 and about 50.

Claim 12

A composition as defined in claim 1 wherein said radiochromic hindered phenolic stabilizer compries a compound of the formula ##STR2## wherein R 1 , R 2 , R 3 and R 4 are substituents on phenols to provide oxidative and chemical stabilization of polyolefins, and said compound turns yellow when exposed to a sterilizing dose of gamma radiation.

Claim 13

A composition as defined in claim 11 wherein said radiochromic hindered phenolic stabilizer comprises (i) a 3,5-di-t-butyl-4-hydroxyphenyl dihydrocinnamic acid ester of a long chain alcohol, (ii) a 3,5-di-t-butyl-4-hydroxyphenyl dihydrocinnamic acid ester of pentaerythitol, (iii) 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-s-triazine-2,4,6-(1H, 3H, 5H)-trione, or a mixture of any of (i), (ii) and (iii), alone, or in further combination with 2,2'-methylene bis 6-tert-butyl-p-cresol.

Claim 14

A composition as defined in claim 12 wherein said radiochromic hindered phenolic stabilizer comprises (iii) 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-di-methylbenzyl)-s-triazine-2,4,6-(1H, 3H, 5H)-trione.

Claim 15

A composition as defined in claim 1 wherein said blue compound is selected from a diazo condensation violet; a quinacridone magenta; carbozole dioxazine violet; a vat blue or a vat violet; a phthalocyanine blue; an iron blue or a disperse blue dye; a chromium oxide blue; a basic blue of the aryl methane derivative type; an inorganic complex oxide; a solvent blue which is oil soluble; a titanate; or a mixture of any of the foregoing.

Claim 16

A composition as defined in claim 14 wherein said blue compound comprises copper phthalocyanine blue.

Claim 17

A composition as defined in claim 6 wherein said organic thioester (d) comprises distearyl thiodipropionate, dilauryl thiodipropionate, dimyristyl thiodipropionate or a mixture of any of the foregoing.

Claim 18

A composition as defined in claim 16 wherein said organic thioester comprises dilauryl thiodipropionate.

Claim 19

A composition defined in claim 6 wherein said ultraviolet radiation stabilizer comprises a hindered benzoate compound, a polymeric hindered amine compound, or a mixture thereof.

Claim 20

A composition as defined in claim 18 wherein said stabilizer comprises 3,5-di-tert-butyl-4-hydroxybenzoic acid hexadecyl ester.

Claim 21

A composition as defined in claim 18 wherein said stabilizer comprises poly (6-morpholino-5-triazine-2,4-diyl)2,2,6,6-tetramethyl-4-piperidyl)imino) hexamethylene((2,2,6,6-tetramethyl-4-piperidiyl)imino)).

Claim 22

A composition as defined in claim 1 comprising (a) a semi-crystalline polypropylene having a narrow molecular weight distribution having a Q in the range of from about 3 to about 6 and a melt flow range of from about 10 to about 25; (b) from about 0.05 to 0.3 parts by weight per 100 parts by weight of (a) of 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-s-triazine-2,4,6-(1H, 3H, 5H)-trione; (c) from about 4 to about 8 parts by weight per 10 6 parts by weight of (a) of copper phthalocyanine blue; (d) from 0 to about 2.0 parts by weight per 100 parts by weight of (a) of dilauryl thiodipropionate or distearyl thiodipropionate; and (e) from 0 to about 0.5 parts by weight per 100 parts by weight of (a) of 3,5-di-tert-butyl-4-hydroxybenzoic acid hexadecyl ester.

Claim 23

A medical instrument sterilized by gamma irradiation made from the improved composition defined by claim 1.

Claim 24

A medical instrument as defined in claim 22 wherein said medical instrument is a syringe.