Process and composition for preventing the discoloration of radiation sterilized cellulosic material exposed to elevated post-sterilization temperatures

Claim 2

A process for sterilizing cellulosic material which is subject to possible subsequent exposure to undue thermal conditions, said process comprising the steps of: prehumidifying said cellulosic material to a moisture content not less than 6.5% by weight which is sufficient to prevent discoloration of said cellulosic material during a subsquent irradiation step and further sufficient to prevent discoloration of said cellulosic material upon possible thermal conditions after irradiation; sealing said cellulosic material from ambient conditions so as to maintain said cellulosic material at said moisture content; and irradiating said cellulosic material with a sufficient radiation dosage to cause biological death.

Claim 3

A process as set forth in claim 1 wherein said cellulosic material is sealed in a package having low vapor permeability.

Claim 4

A process as set forth in claim 1 wherein the cellulosic material is prehumidified to a moisture content which leaves the material dry to the touch after the material has been irradiated.

Claim 5

A process for sterilizing cellulosic material as set forth in claim 3 wherein the material is prehumidified to a water content within the range from about 8% to about 10% by weight.

Claim 6

A process as set forth in claim 1 wherein the cellulosic material is prehumidified by exposure to air at predetermined temperature and relative humidity.

Claim 7

A process as set forth in claim 5 wherein the cellulosic material is cotton which is prehumidified by exposure to air at 70° F.±2 and at 80%±5% relative humidity for a time period sufficient to stabilize the moisture content of the cotton at not less than 6.5% by weight.

Claim 8

A sterilized cellulosic material capable of resisting discoloration caused by possible subsequent exposure to undue post-sterilization thermal conditions, said material being made by a process comprising: prehumidifying said cellulosic material to a moisture content not less than 6.5% by weight which is sufficient to prevent discoloration of said cellulosic material during a subsequent irradiation step and further sufficient to prevent discoloration of said cellulosic material upon possible thermal conditions after irradiation; sealing said cellulosic material in a package having a low vapor permeability so as to maintain said prehumidified cellulosic material at a moisture content of not less than 6.5% by weight; and irradiating the prehumidified cellulosic material with a sufficient radiation dosage to cause biological death.

Claim 9

A sterilized cellulosic material capable of resisting discoloration caused by possible subsequent exposure to undue post-sterilization thermal conditions, said material being made by a process comprising: prehumidifying said cellulosic material to a moisture content not less than 6.5% by weight which is sufficient to prevent discoloration of said cellulosic material during a subsequent irradiation step and further sufficient to prevent discoloration of said cellulosic material upon possible thermal conditions after irradiation; sealing said cellulosic material in a package having a low vapor permeability so as to maintain said prehumidified cellulosic material at a moisture content of not less than 6.5% by weight; and irradiating the prehumidified cellulosic material with a sufficient radiation dosage to cause biological death.

Claim 10

A sterilized cellulosic material as set forth in claim 7 wherein the material is prehumidified to a water content which leaves the material dry to the touch after the material has been irradiated.

Claim 11

A sterilized cellulosic material as set forth in claim 8 wherein the material is prehumidified to a water content within the range from about 8% to about 10% by weight.

Claim 12

A sterilized cellulosic material as set forth in claim 7 wherein the material is prehumidified to a water content sufficient to prevent visually perceivable discoloration resulting from possible subsequent exposure of the material to post-irradiation temperatures up to and including 150° F.

Claim 13

A sterilized cellulosic material as set forth in claim 10 wherein the material is prehumidified to a water content which leaves the material dry to the touch after the material has been irradiated.

Claim 14

A radiation-sterilized, cellulosic material capable of resisting discoloration upon possible subsequent exposure to undue post-sterilization thermal heating, said material resulting from a process comprising the steps of: prehumidifying said cellulosic material to a predetermined moisture content based upon the weight of the cellulosic material with said moisture content being of a value not less than 6.5% which prevents visually noticeable discoloration of said radiation-sterilized, cellulosic material upon possible subsequent post-sterilization exposure to temperatures up to about 150° F.; sealing said cellulosic material in a package having a low vapor permeability so as to maintain said prehumidified cellulosic material approximately at said predetermined moisture content by weight; and irradiating the prehumidified cellulosic material with a sufficient radiation dosage to cause biological death.

Claim 15

A radiation-sterilized, cellulosic material capable of resisting discoloration upon possible subsequent exposure to undue post-sterilization thermal heating, said material resulting from a process comprising the steps of: prehumidifying said cellulosic material to a predetermined moisture content based upon the weight of the cellulosic material with said moisture content being of a value not less than 6.5% which prevents visually noticeable discoloration of said radiation-sterilized, cellulosic material upon possible subsequent post-sterilization exposure to temperatures up to about 150° F.; sealing said cellulosic material in a package having a low vapor permeability so as to maintain said prehumidified cellulosic material approximately at said predetermined moisture content by weight; and irradiating the prehumidified cellulosic material with a sufficient radiation dosage to cause biological death.

Claim 16

A radiation-sterilized, cellulosic material as set forth in claim 12 wherein the material is prehumidified to a water content within the range from about 8% to about 10% by weight.