Thermotropic adhesive tape

• US 4,188,437 A
• Filed: 05/25/1978
• Issued: 02/12/1980
• Est. Priority Date: 05/25/1978
• Status: Expired due to Term

• Current Assignee: American National Can Company
• Original Assignee: United States Gypsum Company (GEBR Knauf Verwaltungsgesellschaft KG)
• Inventors: Rohowetz, Stanley E.
• Primary Examiner(s): Lesmes, George F.
• Assistant Examiner(s): Hess, Bruce H.
• Application Number:
  US05/909,481
• Time in Patent Office: 628 Days
• Field of Search: 8/1 D, 8/1 G, 8/15, 8/3, 8/4, 8/25, 8/26, 23/230 R, 73/356, 116/114 V, 128/2 H, 252/408, 260/38, 350/359, 428/40, 428/343, 428/344, 428/354, 428/913, 428/207, 428/209
• US Class Current: 428/199
• CPC Class Codes: A61L 2/28 Devices for testing the effectiveness or completeness of sterilisation, e.g. indicators which change colour apparatus involving enzymes or microorganisms C12M1/34; methods involving enzymes or microorganisms C12Q1/00
• CPC Class Codes: C09D 11/50 Sympathetic, colour changing or similar inks
• CPC Class Codes: C09J 7/22 Plastics; Metallised plastics
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/24835 including developable image or soluble portion in coating or impregnation [e.g., safety paper, etc.]
• CPC Class Codes: Y10T 428/24901 including coloring matter
• CPC Class Codes: Y10T 428/24917 including metal layer
• CPC Class Codes: Y10T 428/2804 Next to metal
• CPC Class Codes: Y10T 428/2848 Three or more layers

Abstract

Adhesive tapes which change color in the presence of water or steam at elevated temperature are provided which are useful as sterilization indicators. The tapes comprise an adhesive layer and a polymeric base film containing on one surface thereof a coating of a thermotropic ink comprising a binder resin, a colorant which undergoes a color change in the presence of water or steam at elevated temperature, and a solvent for said binder resin and colorant.

Claims

1. A thermotropic adhesive tape comprising a base layer of a material selected from the group consisting of polymers and metals, an adhesive coating on one surface of said base layer, and colored markings on either the outer surface of said base layer or the surface of said adhesive layer adjacent said base layer so as to be visible thereon;

said markings being formed from an ink composition comprising a solution of (1) about 3-30% by weight of an alcohol-soluble resole binder resin;

(2) about 0.1-5% by weight of a colorant selected from the group consisting of (a) a reactive thermotropic dye capable of exhibiting a visible color change upon exposure to steam at a temperature of at least about 215°

F. and (b) a combination of dyes of different color capable of exhibiting a visible color change upon exposure to water or steam at a temperature of at least about 120°

F., said dye combination including at least one dye which is water-extractible at said temperature and at least one other dye which is not water-extractible at said temperature;

(3) about 65-97% by weight of a solvent blend consisting essentially of (a) about 25-75% of an aliphatic alcohol having 1 to 3 carbon atoms or a mixture thereof and (b) about 25-75% of an organic compound selected from the group consisting of aliphatic and cyclic ketones, aldehydes, acetals, ethers and esters; and

(4) about 0.01-0.1% of a surfactant;

said ink composition being disposed on the outer surface of said base layer when said base layer is a metallic material and also being disposed on said base layer when said ink composition comprises said combination of dyes, said ink composition being adhered to said base layer when said base layer comprises a polymeric material by softening and swelling the surfaces of the polymer to allow penetration of the ink;

said composition being capable of undergoing a visible and permanent color change as seen on said base layer upon exposure to water at a temperature sufficient to activate a change in color of the colorant.

2. An adhesive tape as claimed in claim 1 in which the base layer is a material selected from the group consisting of polypropylene, polyethylene terephthalate and aluminum foil.

3. An adhesive tape as claimed in claims 1 or 2 in which the resole resin binder is an alkaline catalyzed condensation product of an aromatic compound with formaldehyde in which the ratio of formaldehyde to aromatic compound is greater than 1:

1, said aromatic compound being selected from the group consisting of phenol and resorcinol.

4. An adhesive tape as claimed in claim 1 or 2 in which said resole resin has a molecular weight of from about 1,300 to about 10,000.

5. An adhesive tape as claimed in claims 1 or 2 in which the colorant is a reactive thermotropic dye capable of exhibiting a visible color change upon exposure to steam at a temperature of at least about 215°

F.

6. An adhesive tape as claimed in claims 1 or 2 in which the colorant is a phenazine dye derived by diazotization of the reaction product of naphthol and 3,7-diamino-2,8-dimethyl-5-phenyl-phenazinium chloride.

7. An adhesive tape as claimed in claims 1 or 2 in which the colorant is Indoine Blue.

8. An adhesive tape as claimed in claims 1 or 2 in which the colorant is a combination of dyes of different colors capable of exhibiting a visible color change upon exposure to water at a temperature of at least about 120°

F.

9. An adhesive tape as claimed in claims 1 or 2 in which said extractible dye is Aniline Blue, Palacet Yellow or Light Green SF and said non-extractible dye is Safranine O or Victoria Blue.

10. A thermotropic adhesive tape comprising a base layer of a material selected from the group consisting of polypropylene, polyethylene terephthalate, and aluminum foil, an acrylic polymer adhesive coating on one surface of said base layer and colored markings on either the other surface of said base layer or the surface of said adhesive layer adjacent said base layer so as to be visible thereon;

said markings being formed from an ink composition comprising a solution of (1) about 3 to 7 percent by weight of an alcohol-soluble resole resin derived from an alkaline catalyzed condensation product of an aromatic compound selected from the group consisting of phenol and resorcinol with formaldehyde in which the ratio of formaldehyde to said aromatic compound is greater than 1;

1, said resin having a molecular weight within the range of about 1300 L to 10,000;

(2) about 1 to 5 percent by weight of a colorant which is a phenazine dye capable of reacting to undergo a visible color change when exposed to steam at a temperature of at least about 215°

F.;

(3) a solvent consisting essentially of about 25 to 75 percent by weight of an alcohol selected from the group consisting of methanol and ethanol and about about 25 to 75 percent by weight of ethylene glycol monomethyl ether; and

(4) about 0.01-0.1 percent by weight of a fluorinated alkyl ester surfactant, said solvent comprising the remainder of said composition;

said ink composition being disposed on the outer surface of said base layer when said base layer is aluminum foil, said ink composition being adhered to said base layer when said base layer comprises one of the polymeric materials by softening and swelling the surfaces of said polymeric material to allow penetration of the ink into the body thereof, and undergoing a visible and permanent color change as seen on said base layer upon exposure to steam at a temperature of at least about 215°

F.

11. An adhesive tape as claimed in claim 10 in which said colorant is Indoine Blue.

12. A thermotropic adhesive tape comprising a base layer of a material selected from the group consisting of polypropylene, polyethylene terephthalate, and aluminum foil, an acrylic polymer adhesive coating on one surface of said base layer and colored markings applied to the other surface of said base layer so as to be visible thereon;

said markings being formed from an ink composition comprising a solution of (1) about 3 to 7 percent by weight of an alcohol-soluble resole resin derived from an alkaline catalyzed condensation product of an aromatic compound selected from the group consisting of phenol and resorcinol with formaldehyde in which the ratio of formaldehyde to said aromatic compound is greater than 1;

1, said resin having a molecular weight within the range of about 1300 to 10,000;

(2) about 1 to 5 percent by weight of a colorant which is a combination of dyes of different color comprising an extractible/non-extractible pair, said combination of dyes being capable of undergoing a visible color change upon exposure to water at a temperature of at least about 120°

F.;

(3) a solvent consisting essentially of about 25 to 75 percent by weight of an alcohol selected from the group consisting of methanol and ethanol and about 25 to 75 percent by weight of dimethyl formamide; and

(4) about 0.01-0.1 percent by weight of a fluorinated alkyl ester surfactant, said solvent comprising the remainder of said composition, said dye pair including one dye which is not water-extractible at said temperature; and

one dye which is water extractible at said temperature;

said ink composition being disposed on the outer surface of said base layer and adhered to said base layer when said base layer comprises one of the polymeric materials by softening and swelling the surfaces of the polymer to allow penetration of the ink into the body thereof and undergoing a visible and permanent color change by extraction of the extractible dye from said base layer upon exposure to water at a temperature of at least about 120°

F.

13. An adhesive tape as claimed in claim 12 in which the extractible dye is Aniline Blue, Palacet Yellow or Light Green SF and said non-extractible dye is Safranine O or Victoria Blue.

14. A thermotropic adhesive tape comprising a base layer of a material selected from the group consisting of polypropylene and polyethylene terephthalate, an acrylic ester polymer adhesive layer on one surface of said base layer and colored markings on either the other surface of said base layer or the surface of said adhesive layer adjacent said base layer, said markings being formed from an ink composition comprising a solution of about 5% by weight of alcohol-soluble phenol-formaldehyde resole resin, about 1% by weight Indoine Blue dye, about 47% by weight methanol, about 47% by weight methyl cellosolve and about 0.1% by weight fluorinated alkyl ester surfactant, said composition being capable of undergoing a visible and permanent color change upon exposure to steam at a temperature of at least about 215°

F.

15. A thermotropic adhesive tape comprising an aluminum foil base layer, an acrylic ester adhesive layer on one surface of said base layer and colored markings on either the other surface of said base layer or the surface of said adhesive layer adjacent said base layer, said markings being formed from an ink composition comprising a solution of about 5% by weight of an alcohol-soluble phenol-formaldehyde resole resin, about 1% by weight Indoine Blue dye, about 47% by weight methanol, about 47% by weight methyl cellosolve and about 0.1% by weight fluorinated alkyl ester surfactant, said composition being capable of undergoing a visible and permanent color change upon exposure to steam at a temperature of at least about 215°

F.

16. A thermotropic adhesive tape comprising a base layer of a material selected from the group consisting of polypropylene, polyethylene terephthalate, and aluminum foil, an acrylic ester adhesive layer on one surface of said base layer and colored markings on the other surface of said base layer, said markings being formed from an ink composition comprising a solution of about 7% by weight of an alcohol-soluble phenol-formaldehyde resole resin, about 1% by weight of a mixture of Safranine O and Light Green SF in a weight ratio of about 1:

2, about 45% by weight methanol, about 45% by weight dimethyl formamide and about 0.04% by weight fluorinated alkyl ester surfactant, said composition being capable of undergoing a visible and permanent color change upon exposure to water at a temperature of at least about 120°

F.

17. A thermotropic adhesive tape comprising an aluminum foil base layer, an acrylic ester adhesive layer on one surface thereof and colored markings on the other surface of said base layer, said markings being formed from an ink composition comprising a solution of about 7% by weight phenol-formaldehyde resole resin, about 1% by weight of a mixture of Safranine O and Light Green SF in a weight ratio of about 1:

2, about 45% by weight methanol, about 45% by weight dimethyl formamide and about 0.04% by weight fluorinated alkyl ester surfactant, said composition being capable of undergoing a visible and permanent color change upon exposure to water at a temperature of at least about 120°

F.

18. A thermotropic adhesive tape comprising a base layer of a material selected from the group consisting of polymers and metals, an adhesive coating on one surface of said base layer, and colored markings on either the outer surface of said base layer or the surface of said adhesive layer adjacent said base layer so as to be visible thereon;

said markings being formed from an ink composition comprising a solution of (1) about 3-30% by weight of an alcohol-soluble resole binder resin;

(2) about 0.1-5% by weight of a colorant selected from the group consisting of (a) a reactive thermotropic dye capable of exhibiting a visible color change upon exposure to steam at a temperature of at least about 215°

F. and (b) a combination of dyes of different color capable of exhibiting a visible color change upon exposure to water or steam at a temperature of at least about 120°

F., said dye combination including at least one dye which is water-extractible at said temperature and at least one other dye which is not water-extractible at said temperature; and

(3) about 65-97% by weight of a solvent blend consisting essentially of (a) about 25-75% of an aliphatic alcohol having 1 to 3 carbon atoms or a mixture thereof and (b) about 25-75% of an organic compound selected from the group consisting of aliphatic and cyclic ketones, aldehydes, acetals, ethers and esters;

said ink composition being disposed on the outer surface of said base layer when said base layer is a metallic material and also being disposed on said base layer when said ink composition comprises said combination of dyes, said ink composition being adhered to said base layer when said base layer comprises a polymeric material by softening and swelling the surfaces of the polymer to allow penetration of the ink;

said composition being capable of undergoing a visible and permanent color change as seen on said base layer upon exposure to water at a temperature sufficient to activate a change in color of the colorant.

19. An adhesive tape as claimed in claim 18 in which the base layer is a material selected from the group consisting of polypropylene, polyethylene terephthalate and aluminum foil.

20. An adhesive tape as claimed in claims 18 or 19 in which the resole resin binder is an alkaline catalyzed condensation product of an aromatic compound with formaldehyde in which the ratio of formaldehyde to aromatic compound is greater than 1:

1, said aromatic compound being selected from the group consisting of phenol and resorcinol.

21. An adhesive tape as claimed in claims 18 or 19 in which the colorant is a reactive thermotropic dye capable of exhibiting a visible color change upon exposure to steam at a temperature of at least about 215°

F.

22. An adhesive tape as claimed in claims 18 or 19 in which the colorant is a combination of dyes of different colors capable of exhibiting a visible color change upon exposure to water at a temperature of at least about 120°

F.