Cholesteric liquid crystal formulations and time/temperature monitoring means

Claim 2

Time/temperature-monitoring means comprising a choloesteric liquid crystal material having an irreversible phase wherein said material quenched from a first temperature at or above its color-play temperature range to a second temperature below its color-play temperature range while retaining a color characteristic of said material at said material at said first temperature, wherein said material has a pseudo-irreversible liquid crystal phase at a temperature below said color-play temperature range and at a temperature above said irreversible phase, said pseudo-irreversible phase being the only phase located between said color-play temperature range and said irreversible phase, said material having a defined time-dependent temperature-dependent limit said pseudo-irreversible liquid crystal phase, wherein when said limit is exceeded, said material exhibits a color change which is irreversible by cooling.

Claim 3

The time/temperature-monitoring means of claim 1 suitable for monitoring a heat-degradable physiologically active substance contained in a heat conductive container and maintained at a holding temperature below said defined limit-temperature, said time/temperature-monitoring means being adapted to be placed in heat-transfer relation to said container at said holding temperature and upon warming to a limit-temperature in the pseudo-irreversible range exhibits an irreversible color change when said substance reaches said defined limit-temperature, thereby providing a visual indication of whether the temperature of said substance has risen to said defined limit-temperature at any time after said time-temperature-monitoring means was placed in said heat-transfer relation.

Claim 4

Time/temperature-monitoring means of claim 2 wherein said substance comprises a biological, a blood component, or a polymeric synthetic blood product.

Claim 5

Time/temperature-monitoring means of claim 2 wherein said substance comprises a blood component and said container is a medical blood bag.

Claim 6

Time/temperature-monitoring means of claim 4 wherein said defined limit-temperature is about 10° C.

Claim 7

Time/temperature-monitoring means of claim 2 wherein said material includes at least one member selected from the group consisting of cholesteryl benzoate and dicholesteryl carbonate.

Claim 8

Time/temperature-monitoring means of claim 6 wherein said material also includes cholesteryl p-nonylphenyl carbonate.

Claim 9

Time/temperature-monitoring means as defined in claim 7 wherein said material further includes cholesteryl nonanoate.

Claim 10

Time/temperature-monitoring means of claim 2 wherein said cholesteric liquid crystalline material exhibits a glass-transition temperature range of -7° to +10.5° C.

Claim 11

Time/temperature-monitoring means of claim 9 wherein said cholesteric liquid crystalline materials comprise cholesteryl p-nonylphenyl carbonate, cholesteryl nonanoate, cholesteryl benzoate and discholesteryl carbonate.

Claim 12

Time/temperature-monitoring means of claim 10 wherein said material includes, in approximate percentage by weight, 27.0% cholesteryl p-nonylphenyl carbonate, 31.0% cholesteryl nonanoate, 20.0% cholesteryl benzoate, and 22.0% dicholesteryl carbonate.

Claim 13

Time/temperature-monitoring means of claim 2 wherein said cholesteric liquid crystalline material exhibits a glass-transition temperature range of -8° to +4° C.

Claim 14

Time/temperature-monitoring means of claim 12 wherein said cholesteric liquid crystalline materials comprise cholesteryl p-nonylphenyl carbonate, cholesteryl nonanate, cholesteryl benzoate and dicholesteryl carbonate.

Claim 15

Time/temperature-monitoring means of claim 13 wherein said materials includes in approximate percentage by weight, 24.4% cholesteryl p-nonylphenyl carbonate, 29.1% cholesteryl nonanoate, 8% cholesteryl benzoate and 21.9% dicholesteryl carbonate.

Claim 16

Time/temperature-monitoring means of claim 2 and further comprising a second cholesteric liquid crystal-line material which when the said time/temperature-monitoring means is placed in said heat-transfer relation exhibits a reversible color change in its color-play temperature range as the temperature of said time/temperature-monitoring means approaches said defined limit-temperature.

Claim 17

Time/temperature-monitoring means of claim 15 wherein said substance comprises a blood component, said defined limit temperature is about 10° C., and said second material exhibits said color change when the temperature of said substance is in a range of about 1° C. to 9° C.

Claim 18

Time/temperature-monitoring means of claim 15 wherein said first-named materials includes cholesteryl p-nonylphenyl carbonate, cholesteryl nonanoate, cholesteryl benzoate, and dicholesteryl carbonate; and said second material includes cholesteryl nonanoate, cholesteryl oleyl carbonate, and cholesteryl chloride.

Claim 19

Time/temperature-monitoring means as defined in claim 17 wherein the components of said materials are present in the following approximate proportions, in percentages by weight: ______________________________________ First Named Material Component Proportion ______________________________________ Cholesteryl p-nonylphenyl carbonate 27.0 Cholesteryl nonanoate 31.0 Cholesteryl benzoate 20.0 Dicholesteryl carbonate 22.0 Second Material Cholesteryl nonanoate 55.4 Cholesteryl oleyl carbonate 33.4 Cholesteryl chloride 11.2 ______________________________________

Claim 20

Time/temperature-monitoring means of claim 1 suitable for monitoring a heat-conductive container encasing a substance and maintained at a holding temperature below a defined limit-temperature for minimizing degradation thereof, said time/temperature-monitoring means being adapted to be placed in heat-transfer relation to said container at said holding temperature and comprising a cholesteric liquid crystalline material dispersed in a film-forming polymer matrix, said material being capable of existing at a temperature below its color-play temperature range in characteristic mestable ordered glass state exhibiting a color normally exhibited in its color-play temperature range, the color of said material irreversibly changing, upon warming to its limit-temperature, and when the time/temperature-monitoring means is placed in said heat-transfer relation said material exhibiting an irreversible color change when said substance substantially reaches said defined limit-temperature upon warming, thereby providing a visual indication of whether the temperature of the substance has risen substantially to said defined limit-temperature at any time after the temperature-monitoring means is placed in said heat-transfer relation.

Claim 21

Time/temperature-monitoring means of claim 19 wherein said substance comprises a biological, a blood component, or a polymeric synthetic blood product.

Claim 22

Time/temperature-monitoring means of claim 20 wherein said material is microencapsulated in capsules formed of gelatin-gum arabic, and the capsules are dispersed in said matrix.

Claim 23

Time/temperature-monitoring means of claim 21 wherein said matrix is polyvinyl alcohol.

Claim 24

Time/temperature-monitoring means of claim 19 wherein said substance comprises a blood component and said container is a medical blood bag.

Claim 25

Time/temperature-monitoring means of claim 23 wherein said defined limit-temperature is about 10° C.

Claim 26

Time/temperature-monitoring means of claim 19 wherein said material is microencapsulated, and the capsules are dispersed in said matrix.

Claim 27

Time/temperature-monitoring means of claim 25 wherein said capsules are formed of gelatin-gum arabic.

Claim 28

Time/temperature-monitoring means of claim 26 wherein said matrix is polyvinyl alcohol.

Claim 29

Time/temperature-monitoring means of claim 19 wherein said material is dispersed in said matrix in the form of finely divided naked aggregates.

Claim 30

Time/temperature-monitoring means of claim 28 wherein said matrix is polyvinyl butyral, polyurethane, or an acrylic resin.

Claim 31

Time/temperature-monitoring means of claim 19 and further comprising a second cholesteric liquid crystalline material dispersed in a second film-forming polymer matrix, said second material when the temperature-monitoring means is placed in said heat-transfer relation exhibiting a reversible color change in its color-play temperature range when the temperature of said substance approaches said defined limit-temperature upon warming, to give a visual warning of such approach.

Claim 32

Time/temperature-monitoring means of claim 30 wherein said substance comprises a blood component, said defined temperature is about 10° C., and said second material exhibits said color change when the time/temperature of said substance is in a range of about 7° C. to 9° C.

Claim 33

Time/temperature-monitoring means of claim 30 wherein each of said first and second materials is microencapsulated, and the capsules containing the materials are dispersed in their respective matrices.

Claim 34

Time/temperature-monitoring means of claim 32 wherein said capsules are formed of gelatin-gum arabic, and for each matrix the polymer is polyvinyl alcohol.

Claim 35

Time/temperature-monitoring means of claim 30 wherein each of said first and second materials is dispersed in its matrix in the form of finely divided naked aggregates, and for each matrix the polymer is polyvinyl butyral, polyurethane, or an acrylic resin.