TEMPERATURE INDICATOR USEFUL AS A STEAM TRAP MONITOR

INDICATEUR THERMOMETRIQUE POUR DISPOSITIF ASSECHEUR DE VAPEUR

English Abstract

ABSTRACT OF THE DISCLOSURE
There is disclosed a temperature indicator particularly
useful as a steam trap monitor. The temperature is indicated
through the action of a composition of matter placed on an absor-
bent layer and formed of (1) a solvent made of substance(s)
adapted to change from a solid state at substantially a predeter-
mined temperature to a liquid state and (2) an indicator system
formed of substances different from the solvent and which are
soluble in the solvent when it is in the liquid state and which
can change color visible to the naked eye when the solvent passes
from the solid to the liquid state or from the liquid to the solid
state. A representative indicator system is a mixture of bromo-
chlorophenol blue and ethyl red and a representative solvent is
.alpha.,.alpha.'-dichloro-p-xylene. The absorbent layer containing the
temperature indicating composition is sandwiched between a trans-
parent tape for viewing purposes, a layer of adhesive, and a
paper backed foil. Another layer of adhesive is used as the
outer layer for attachment to a steam pipe or the like.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A temperature indicator for measuring temperature,
particularly useful as a steam trap monitor, consisting
essentially of:
a layer of paper-backed foil having a viewing area;
a layer of adhesive corresponding to said layer of
paper-backed foil located adjacent thereof;
a transparent tape located adjacent to said layer of
adhesive and continuing across the viewing area in said layer of
adhesive and said layer of paper-backed foil;
an absorbent layer containing a composition of matter
consisting essentially of:
(1) a solvent (I) consisting of a single substance or a
mixture of substances adapted to change from a solid state at
substantially a predetermined temperature to a liquid state; and
(2) an indicator system (II) consisting of one or more
substances different from (I), and inert to (I), further charac-
terized in that
(a) (II) is soluble in (I) when the latter is in the
liquid state; and
(b) (II) changes color visible to the naked eye when
(I) passes from the solid to the liquid state or from the liquid
to the solid state;
a layer of paper-backed foil located adjacent said
absorbent layer and the portions of said transparent tape not in
direct communication with said absorbent layer; and
a layer of adhesive located adjacent said layer of
paper-backed foil.
14

2. The temperature indicator according to claim l wherein
the solubility of the indicator system (II) in the solvent (I),
when the latter is in the solid state, is so much lower than the
solubility of (II) in (I), when the latter is in the liquid
state, that (II) is partly or entirely separated while (I) passes
from the liquid to the solid state.
3. The temperature indicator according to claim 1
wherein said composition of matter exhibits a sharp color change
upon transition from a liquid state to a solid state or from a
solid state to a liquid state capable of being supercooled for
at least several minutes, and consists essentially of
(a) a solvent adapted to change from a solid state at
a predetermined temperature to a liquid state, and
(b) an effective amount of at least one organic moiety
dissolved in and inert towards said solvent to form a solid
solution when the composition is in the solid state and adapted
to change the color of the composition visible to the naked eye
upon the change of state of the solvent at substantially the
predetermined temperature when so dissolved, and selected from
one or more of the group consisting of
(1) a group of single compounds consisting of the
following classes of compounds: cyanine, monoazo, disazo, tri-
aryl-methane, xanthene, sulphone, phthalein, acridine, quinoline,
azine, oxazine, thiazine, anthraquinone, indigoid, and the
following individual compounds: Aurantia, Orasol orange RLN,
Diamin green B, Direct green G, Fast red salt 3 GL, Fast blue
salt BB, Fast garnet salt GBC, Carta yellow G 180%, Murexide,
Savinyl blue GLS, Irgalith blue GLSM, phthalocyanine, and
Alcannin,
(2) mixtures of
(a) one or more organic acid compounds having a
pK of less than about four, and

(b) one or more basic dyes or basic indicators,
(3) mixtures of
(a) one or more organic acids having a pK of
less than about 2, and
(b) one or more acid dyes or acidic indicators,
(4) mixtures of
(a) one or more organic acid compounds having a
pK of less than about 4, and
(b) one or more of a group III body of compounds
consisting of pinacyanol iodide, 1,1'-diethyl-2,2'-cyanine iodide,
quinaldine red, pinacyanol chloride, thionin, methylene blue,
cresol red, chlorophenol red, neutral red iodide, neutral red
chloride, crystal violet, acridin orange, Orasol Orange RLN
Orasol Navy BlueTM, Irgalith Red PRTM, Fat Red BSTM, Xylene Cyan-
ol FFTM, Rhodamine BTM, Rhodamine 6GTM, Irgalith Magenta TCBTM,
Irgalith Pink TYNCTM, Toluidine Blue OTM, Savinyl Green BTM,
Savinyl Blue RSTM, purpurin, 3,3'-diethylthiadicarbocyanine
iodide, cryptocyanine, Dicyanine ATM, Merocyanine 540TM, 4-(p-
ethoxyphenylazo)-m-phenylene diamine monohydrochloride, Yellow
Orange STM, Chrysoidan GTM, fuchsin, aurintricarboxylic acid
(ammonium salt), Victoria Blue RTM, Pyronin GTM, gallein, Erythro-
sin Yellow BlendTM, chlorophenol blue, bromophenol blue, bromo-
cresol purple, Coriphosphine OTM/ acriflavine, acridine orange,
rhoduline violet, Alizarin cyanin 2RTM, Alizarin Red STM,
alcannin, Aurantia, Direct Green GTM, Fast Red Salt 3 GLTM,
Fast Blue Salt BBTM, Fast Garnet Salt GBCTM, Carta Yellow 180
o/oTM, Murexide, Savinyl Blue GLSTM, Irgalith Blue GLSMTM, phthalo-
cyanine, Di Amingreen BTM, Alizarin Blue S, Celliton Blue Extra
neocyanine, Janus Green TM, dimethyl yellow, Fast Yellow TM, methyl
red sodium salt, Alizaxin yellow RTM, Erichrome Black TTM,
Chromotrope 2RTM, Ponceau 6RTM, Brilliant Ponceau G/R/2RTM,
chromolan yellow, Sudan Red BTM, Bismarck brown GTM, Fat Black TM,
16

Resorcin BrownTM, senzofast pink 2BLTM, Oil Red EGNTM, Euroglauc-
ine, Fuchsin NBTM, parafuchsin, Patent BlueTM, Irgalith Blue
TNCTM, Phloxin BTM, fluorescein sodium salt, Rhodamine B baseTM,
Eosin Scarlet, Eosin YellowishTM, Erythrosin extra bluish,
4,5-dibromofluorescein, ethyleosin, PhloxineTM, Cyanovin BTM,
chlorocresol green, pinacyanol bromide, 2-(p-dimethylaminostyryl)-
1-ethyl pyridinium iodide, ethyl red, nigrosine, Savinyl Blue BTM,
Orasol Blue BLNTM, Safrainin OTM, Azocarnun GTM, PhenosafranineTM,
Azocarmine BXTM, Solophenyl Brilliant Blue BLTM, Nile Blue ATM,
gallocyanine, gallamine blue, celestine blue, methylene green,
Azure A/B/CTM, Blue VIF OrganolTM, Alizarin, Nitrofast Green
GSB , quinalizarine, Oil Blue N M, Solvay purple, Ciba Blue
Indigo syntheticTM, Chromophtal Bordeaux RSTM, Acid Alizarin Red
BTM, 5-Aminofluorescein, Rose BengalTM, Martius YellowTM, Chicago
Blue 6BTM, Alcian Blue 8GXTM, cresyl violet, 4,4'-Bis(dimethyl-
amino)benzylhydrol, zinc Phthalocyanine, Sudan IIITM, Pyronin yTM,
Toluylene BlueTM, cresyl violet perchlorate, Mendola's BlueTM,
Phosphine Dye, NitronTM, cresyl violet acetate, Ceres Orange RTM,
4-phenylazo-1-naphthyl-amine, 4-(4-Dimethylamino-l-naphthalazo)-
3-methoxybenzene sulfonic acid, Bindschedler's Green M, and p-(p-
dimethylaminophenylazo)benzoic acid,
(5) mixtures of
(a) one or more basic dyes or basic indicators,
and
(b) one or more members of the group III body
of compounds, and
(6) mixtures of
(a) one or more dyes having a molecular structure
containing a lactone group, and
(b) one or more acids having a pK of about 8 to
about 12.
17

4. The temperature indicator according to claim 1. wherein
said composition of matter exhibits a sharp color change upon
transition from a liquid state to a solid state or from a solid
state to a liquid state capable of being supercooled for at
least several minutes, and is substantially free of impurities,
consisting essentially of:
(a) a solvent adapted to change from a solid state
at substantially a predetermined temperature to a liquid state;
and
(b) an effective amount of at least one organic
moiety dissolved in and inert towards said solvent to form a
solid solution when the composition is in the solid state and
adapted to change the color of the composition visible to the
naked eye
18

upon the change in state at substantially the predetermined temp-
erature when so dissolved, and selected from one or both of the
group consisting of:
(1) one or more of a group III body of compounds
consisting of pinacyanol iodide, 1,1'-diethyl-2,2'-cyanine iodide,
quinaldine red, pinacyanol chloride, thionin, methylene blue,
cresol red, chlorophenol red, neutral red iodide, neutral red
chloride, crystal violet, acridin orange, Orasol Orange RLNTM,
Orasol Navy BlueTM, Irgalith Red PRTM, Fat Red BSTM, Xylene Cyan-
ol FFTM, Rhodamine BTM, Rhodamine 6GTM, Irgalith Magenta TCBTM,
Irgalith Pink TYNCTM, Toluidine Blue OTM, Savinyl Green BTM,
Savinyl Blue RSTM, purpurin, 3,3'-diethylthiadicarbocyanine
iodide, cryptocyanine, Dicyanine ATM, Merocyanine 540TM, 4-(p-
ethoxyphenylazo)-m-phenylene diamine monohydrochloride, Yellow
Orange STM, Chrysoidan GTM, fuchsin, aurintricarboxylic acid
(ammonium salt), Victoria Blue RTM, Pyronin GTM, gallein, Erythro-
sin Yellow BlendTM, chlorophenol blue, bromophenol blue, bromo-
cresol purple, Coriphosphine OTM, acriflavine, acridine orange,
rhoduline violet, Alizarin cyanin 2RTM, Alizarin Red STM,
alcannin, Aurantia, Direct Green GTM, Fast Red Salt 3 GLTM,
Fast Blue Salt BBTM, Fast Garnet Salt GBCTM, Carta Yellow G 180
o/oTM, Murexide, Savinyl Blue GLSTM, Irgalith Blue GLSMTM, phthalo-
cyanine, Di Amingreen BTM, Alizarin Blue S, Celliton Blue Extra
neocyanine, Janus GreenTM, dimethyl yellow, Fast YellowTM, methyl
red sodium salt, Alizarin yellow RTM, Eriochrome Black TTM,
Chromotrope 2RTM, Ponceau 6RTM, Brilliant Ponceau G/R/2RTM,
chromolan yellow, Sudan Red BTM, Bismarck brown GTM, Fat BlackTM,
Resorcin BrownTM, Benzofast pink 2BLTM, Oil Red EGNTM, Euroglaucine,
Fuchsin NBTM, parafuchsin, Patent BlueTM, Irgalith Blue TNCTM,
Phloxin BTM, fluorescein sodium salt, Rhodamine B baseTM, Eosin
Scarlet, Eosin YellowishTM, Erythrosin extra bluish, 4,5-dibromo
fluorescein, ethyleosin, PhloxineTM, Cyanovin BTM, chlorocresol
19

green, pinacyanol bromide, 2-(p-dimethylaminostyry)-1-ethyl
pyridinium iodide, ethyl red, nigrosine, Savinyl Blue BTM,
Orasol Blue BLNTM, Safranin OTM, Azocarnun GTM, PhenosafranineTM,
Azocarmine BXTM, Solophenyl Brilliant Blue BLTM, Nile Blue ATM,
gallocyanine, gallamine blue, celestine blue, methylene green,
Azure A/B/CTM, Blue VIF OrganolTM, Alizarin, Nitrofast Green
GSBTM, quinalizarine, Oil Blue NTM, Solvay purple, Ciba BlueTM,
Indigo syntheticTM, Chromophtal Bordeaux RSTM, Acid Alizarin Red
BTM, 5-Aminofluorescein, Rose BengalTM, Martius YellowTM, Chicago
Blue 6BTM, Alcian Blue 8GXTM, cresyl violet, 4,4'-Bis(dimethyl-
amino)benzylhydrol, zinc Phthalocyanine, Sudan IIITM, Pyronin yTM,
Toluylene BlueTM, cresyl violet perchlorate, Mendola's BlueTM,
Phosphine Dye, NitronTM, cresyl violet acetate, Ceres Orange RTM,
4-phenylazo-1-naphthyl-amine, 4-(4-Dimethylamino-l-naphthalazo)-
3-methoxybenzene sulfonic acid, Bindschedler's GreenTM, and p-(p-
dimethylaminophenylazojbenzoic acid;
(2) a binary mixture of
(A) one or more of a group I body of
compounds soluble in said solvent consisting of the halogenated
sulfonphthaleins and the organic acids having a pK1 less than
about four; and
(B) one or more of a group II body of
compounds consisting of the aminotriphenylmethanes and their
soluble salts, 8-hydroxyquinoline, and the cyanines;
wherein the weight ratio of the group I body of
compounds to the group II body of compounds is more than or
about 3 to 1 and with the proviso that if the group II compounds
consist solely of one or more aminotriphenylmethanes or their
soluble salts, then the group I compound must be selected from
one or more of the group consisting of oxalic acid, suitable
soluble sulfonic acids, and the tetrahalogenated sulfonphthaleins,
and the other organic acids having a pK1 of less than or about 2;
and

(3) one or more of the aforesaid group III body
of compounds with one or more of the group I or group II bodies
of compounds.
5. The temperature indicator according to claim 4 wherein
(a) the group I body of compounds are one or more of the group
consisting of oxalic acid, bromophenol blue, bromothymol blue,
chlorophenol red, bromochlorophenol blue, bromocresol green,
3,4,5,6-tetrabromophenolsulfonphthalein, 2-naphthalene-sulfonic
acid, trichloroacetic acid, chloroanilic acid, bromophenol red,
and chlorocresol green and (b) the group II body of compounds are
one or more of the group consisting of 5-(p-dimethylaminobenzili-
dine)rhodanine, ethyl red, crystal violet, pararosaniline, para-
rosaniline acetate, 3-ethyl-2-~-5-(3-ethyl-2-benzothiazolinylidene)-
1,3-pentadienyl]-benzo-thiazolium iodide, basic fuchsin, 8-hydroxy-
quinoline, ethyl violet, brilliant green, Dicyanine A, pinacyanol
chloride, 2-(p-dimethylaminostyryl)-1-ethyl-pyridinium iodide,
3,3'-diethylthiodicarbocyanine iodide, and cryptocyanine.
6. The temperature indicator according to claim 5 wherein
the weight percentage of organic moieties soluble in the solvent
is from about 0.025 to about 0.05% of the weight of the solvent
and said soluble organic moieties.
7. The temperature indicator according to claim 5 wherein
the solvent is selected from one or more of the group consisting
of ortho-chloronitrobenzene, ortho-bromonitrobenzene, 1-thymol,
2-naphthol, 2-ethoxybenzamide, and naphthalene.
8. The temperature indicator according to claim 5 wherein
the group I compounds consist of the halogenated sulfonphthaleins
having a pK1 of about 2 and a PK2 of about 7 to about 9.
9. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of bromochlorophenol
21

blue and ethyl red.
10. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of bromochlorophenol
blue and ethyl violet.
11. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of bromophenol blue
and basic fuchsin.
12. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of bromophenol red
and brilliant green.
13. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of bromochlorophenol
blue and pinacyanol chloride.
14. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of 3,3'-diethylthio-
dicarbocyanine iodide and bromocresol purple.
15. The temperature indicator according to claim 4 whereinthe
organic moieties selected are a mixture of 3,3'-diethylthiodi-
carbocyanine iodide and bromophenol blue.
16. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of pinacyanol chloride
and 3,4,5,6-tetrabromophenolsulfonphthalein.
17. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of pinacyanol chloride
and bromocresol purple.
18. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of ethyl red and bromo-
chlorophenol blue.
22

19. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of pinacyanol chloride
and chlorocresol green.
20. The temperature indicator according to claim 4 wherein
the organic moiety selected is pinacyanol iodide.
21. The temperature indicator according to claim 4 wherein
the organic moiety selected is guinaldine red.
22. The temperature indicator according to claim 4 wherein
the organic moiety is 1,1-diethyl-2,2'-cyanine iodide.
23. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of chlorophenol blue
and ethyl red.
24. The temperature indicator according to claim 4 wherein
the organlc moieties selected are a mixture of bromophenol blue
and ethyl red.
25. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of chlorophenol red
and ethyl red.
26. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of ethyl red and
3,4,5,6-tetrabromophenolsulfonphthalein.
27. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of ethyl red and
bromophenol red.
28. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of pinacyanol chloride
and bromochlorophenol blue.
23

29. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of ethyl red and
bromocresol purple.
30. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of crystal violet and
bromophenol blue.
31. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of bromochlorophenol
blue and brilliant green.
32. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of naphthalene sul-
fonic acid and ethyl violet.
33. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of naphthalene sulfonic
acid and crystal violet.
34. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of naphthalene sulfonic
acid and ethyl red.
35. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of trichloroacetic
acid and cryptocyanine.
36. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of trichloroacetic
acid and ethyl violet.
37. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of 3-ethyl-2-[5-(3-
ethyl-2-benzothiazolinylidene)-1,3-pentadienyl]-benzothiazolium
iodide and trichloroacetic acid.
24

38. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of chloroanilic acid
and basic fuchsin.
39. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of chlorophenol red
and dicyanine A.
40. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of chlorophenol red
and cryptocyanine.
41. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of bromochlorphenol
blue and dicyanine A.
42. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of 5-p-dimethylamino-
benzylidine rhodanine and dicyanine A.
43. The temperature indicator according to claim 4 wherein
the organic moieties selected are a mixture of 5-p-dimethylamino-
benzylidine rhodanine and cryptocyanine.
44. The temperature indicator according to claim 1 wherein
the layer of paper-backed foil is a paper-backced aluminum foil.
45. The temperature indicator according to claim 1 wherein
the layer of adhesive is a silicone adhesive.
46. The temperature indicator according to claim 1 wherein
said transparent tape is a polyimide tape.
47. The temperature indicator according to claim 46 wherein
said polyimide tape also contains a silicone adhesive.
48. The temperature indicator according to claim 1 wherein

said absorbent layer has a filter paper base.
26

Description

3L~2;2 ~L~2
The present invention relates to a temperature indicat
or particularly useful as a steam trap monitor.
The invention relates to the field of temperature-
indicating compos1tions and devices therefor, and in particular,
the sub-fields of disposable steam trap indicators and compositions
of matter which change characteristics with change in phases for
use in disposable thermometers.
A variety of temperature indicators have been used in
the past to determine temperature xanges in general and in certain
instances for determining leaks in steam traps. A disadvantage
of the prior art temperature indicators for steam trap monitors
is that they are irreversible, i.e., when a preset -temperature is
ascertained, the steam trap monitor changes color but no provision
is made for allowing the monitor, to revert to an original operating
mode after the temperature is indicated. A representative meas-
uring defice of this type is the Wahl TEMP-PLATE* temperature
recorders that contain from one to several sealed heat sensitive
elements that change chemical structure at a given calibrated
temperature. As each indicator, ordinarily pearl gray, is
exposed to a heat exceeding the calibrated temperature, the
indicator will permanently and irreversibly turn black in less
than one second. It is impossible for an indicator of this
type to be used in more than one application.
Furthermore, the rapidly increasing cost of producing
steam in the last few years has resulted in a renewed interest
in efficient steam trapping and good trap maintenance. The
wisdom of good steam trap maintenance becomes evident when one
considers that, based on the current cost of producing steam,
a 100 psi line that has a one-half inch ]eaking trap results in
a ~30,000 per year loss. In order to eliminate or reduce losses
* Trade Mark
-- 1 --
.~ ~

Z4~;~
of this type, steam traps must be routinely checked for leaks.
The frequency of these checks can vary from daily inspection of
very critical operations at pressures of 200 psi and over to
semi-annual inspections of very low pressure systems. Recommended
methods for checkin~ steam traps to date have included:
(1) thermometers inserted in lines between equipment and
traps;
(2) pressure gauges on steam supply sys-tems and at
condensate receiver tanks;
(3~ listening devices such as a steel rod, a long screw-
driver, or an industrial stethoscope; and
(4) portable contact pyrometers for measuring temperatures
on both sides of the traps~
Since these methods are either expensive or time consuming or
both, there is a need for a simple, inexpensive way to monitor
steam traps.
It is therefore an object of the present invention to
provide a temperature indicator useful as a steam trap monitor
that can be modified to permit its use in a variety of environ-
ments.
It is also an object of the present invention toprovide a temperature indicator useful as a steam trap monitor
that can be calibrated so that there is a minimum number of
materials required along a steam line system.
It is ~urther an object of the present invention to
provide a temperature indicator useful as a steam trap monitor
that can be used more than once, permitting its retention on
the steam line or other object whose temperature is being recorded~
It is furthermore an object of the present invention
to provide a temperature indicator useful as a steam trap monitor
that can be modified to function at a variety of predetermined
temperature ranges.
-- 2 --

It is also an object oE the present invention to
provide a temperature indicator useful as a steam trap monitor
that has a relatively simple construction and good durability.
The instant invention is based on the discovery of
a temperature indicator useful as a steam trap monitor whose
temperature is indicated through the action of a composition of
matter placed on an absorbent layer and formed of tl) a solvent
made of substance(s) adapted to change from a solid state at
substantially a predetermined temperature to a li~uid state
and (2) an indicator system formed of substances different ~rom
the solvent and which are soluble in the solvent ~hen it is in
the liquid state and which can change color visible to the naked
eye when the solvent passes from the solid to the li~uid state
or from the liquid to the solid state.
The invention accordingly provides a temperature
indicator for measuring temperature, particularly useful as a
steam trap monitor, consisting essentially of:
a layer of paper-backed foil having a viewing area;
a layer of adhesive corresponding to said layer of
0 paper-backed foil located adjacent thereto;
a transparent tape located adjacent to said layer of
adhesive and continuing across the viewing area in said layer of
adhesive and said layer of paper-backed foil;
an absorbent layar containing a composition of matter
consisting essentially of:
(1) a solvent ~I) consisting of a single substance or
a mixture of substances adapted to change from a
solid state at substantially a predetermined tempera-
ture to a liquid state; and
(2~ an indicator system (II) consisting of one or more
substances different from (I3, and inert to ~I), further
characterized in that
--3--

z
(a) (II) is soluble in (I) when the latter is in the
liquid state; and
(b) (II) changes color visible to the naked eye when
(I) passes from the solid to the liquid state or from
the liquid to the solid state;
a layer of paper backed foil located adjacent said
absorbent layer and the portions of said transparent tape not in
direct communication with said absorbent layer; and
~ a layer of adhesive located adjacent said layer of paper
backed foil.
The composition of matter is more particularly described ~-
in our Canadian application filed on even date herewith, inventors:
Hof and Ulin, entitled "Temperature Indicating Compositions of
Matter", Serial No. 313,986. The compositions of matter useful
for the above application are likewise useful herein as the con-
cept of formulating a reversible temperature indicating composition
has joint applicability.
According to a preferred embodiment of the invention,
the solubility of the indicator system (II) in the solvent (I),
when the latter is in the solid state, is so much lower than the
solubility of (II) in (I), when the latter is in the llquid state,
that (II) is partly or entirely separated while ~I) passes from
the liquid to the solid state.
The indicator system (II) is preferably an effective
amount of at least one organic moiety dissolved in and inert
towards said solvent to form a solid solution when the composition
is in the solid state and adapted to change the color of the
composition visible to the naked eye upon the change of state
of the solvent at substantially the predetermined temperature
when so dissolved, and selected from one or more of the group
consisting of
(1) a group of single compounds consisting of -the following
-- 4 --

Za~42
classes of compounds: cyanine, monoazo, disazo, triaryl-methane,
xanthene, sulphone, phthalein, acridlne, quinoline, azine, oxa-
zine, thiazine, anthraquinone, indigoid, and the following in-
dividual compounds: Aurantia, Orasol orange RLN, Diamin green
B, Direct green G, Fast red salt 3 GL, Fast blue salt Bs, Fast
garnet salt GBC, Carta yellow G 180%, Murexide, Savinyl blue GLS,
Irgalith blue GLSM, phthalocyanine, and Alcannin,
(2) mi~tures of (a) one or more organic acid compounds
having a pK of less than about four, and (b) one or more basic
dyes or basic indicators,
(3) mixtures of (a) one or more organic acids having a
pK of less than about 2, and (b) one or more acid dyes or acldic
indicators,
(4) mixtures of (a) one or more organic acid compounds
having a pK of less than about ~, and (b) one or more members
of the group III body of compounds,
(5) mixtures of (a) one or more basic dyes or basic
indicators, and (b) one or more members of the group III body
of compounds, and
(6) mixtures of (a) one or more dyes having a molecular
structure containing a lactone group, and (b) one or more acids
having a pK of about 8 to about 12. Still more preferably the
organic moiety or moieties is/are selected from the group
consisting of:
(1) one or more of a group III body of compounds
consisting of pinacyanol iodide, l,l'-d,iethyl 2,2'-cyanine iodide,
quinaldine red, pinacyanol chloride, thionin, methylene blue,
cresol red, chlorophenol red, neutral red iodide, neutral red
chloride, crystal violet, acridin orange, Orasol Orange RLN
Orasol Navy Blue , Irgalith Red PRTM, Fat Red BS , Xylene
Cya~ol FFTl, Rhodamine BTM, Rhodamine 6GT , Irgalith Magne,ta TCB
Irgalith Pink TYNC , Toluidine Blue O , Savinyl Green sTM,
Savinyl Blue RS , purpurin, 3,3'-diethylthiadicarbocyanine io-
- 5 -

4;~
dide, cryp-tocyanlne, Dicyanine ATM, Merocyanine 540TM, 4-~p-
ethoxyphenylazo)-m-phenylene diamine monohydrochloride, Yellow
Orange ST~, Chrysoidan GTM, fuchsin, aurintricarboxylic acid
(ammonium salt), Victoria Blue R , Pyronin G M, gallein, Ery-
throsin Yellow BlendTM, chlorophenol blue, bromophenol blue,
bromocresol purple r Coriphosphine oTM, acrifl.avine, acridine
orange, rhoduline violet, Alizarin cyanin 2RTM, Alizarin Red STM,
alcannin, Aurantia, Direct Green GTM, Fast Red Salt 3GLTM, Fast
Blue Salt BBTM, Fast Garnet Salt GBCTM, Carta Yellow G 180 o/oTM,
Murexide, Savinyl Blue GLST~, Irgalith Blue GLSMTM, phthalocyanine,
Di Amingreen BTM, Alizarin Blue S, Celliton Blue ExtraTM, neocyan-
ine, Janus GreenTM, dimethyl yellow, Fast YellowTM, methyl red
sodium salt, Alizarin yellow RTM, Eriochrome BlackTM, Chromotrope
2RTMt Ponceau 6RTM, Brilliant Ponceau G/R/2RTM, chromolan yellow,
Sudan Red BTM, Bismarck brown GTM, Fat BlackTM, Resorcin BrownTM,
Benzofast pink 2BLTM, Oil Red EGNTM, Euroglaucine, Fuchsin NBTM,
parafuchsin, Patent BlueTM, Irgalith Blue TNCTM, Phloxin BTM,
fluorescein sodium salt, Rhodamine B baseTM, Eosin Sca:rlet,
Eosin YellowishTM, Erythrosin extra bluish, 4,5-dibromo fluorescein,
ethyleosin, PhloxineTM, Cyanovin BTM, chlorocresol green, pina-
cyanol bromide, 2-(p-dimethylaminostyryl)-1-ethyl pyridinium io-
dide, ethyl red, nigrosine, Savinyl Blue BTM, Orasol Blue BLNTM,
Safranin oTM/ Azocarnun GTM, PhenosafranineTM, Azocarmine BXTM,
Solophenyl Brilliant Blue BLTM, Nile Blue ATM, gallocyanine,
gallamine blue, celestine blue, methylene green, Azure A/B/CTM,
Blue VIF OrganolTM, Alizarin, Nitrofast Green GSBTM, quinalizarine,
Oil Bl.ue NTM, Solvay purple, Ciba BlueTM, Indigo syntheticTM,
Chromophtal Bordeaux RSTM, Acid Alizarin Red BTM, 5-Aminofluores-
cein, Rose BengalTM, Martius YellowTM, Chicago Blue ~BTM, Alcian
Blue 8GXTM, cresyl violet, ~,4'Bi.s(dimethylamino)benzylhydrol,
zinc Phthalocyanine, Sudan IIITM, Pyronin yTM~ Toluylene BlueTM,
cresyl violet perchlorate, Melola's BlueTM, Phosphine Dye,

;29L4~
Nitron , cresyl violet acetate, Ceres Orange R , 4-phenylazo-
l-naphthyl-amine, 4-(4-dimethylamino-l-naphthalazo)-3-methoxy-
benzene sulfonic acid, Bindschedler's GreenTM, and p-(p-dimethyl-
aminophenylazo)benzoic acid;
(2) a binary mixture of (A) one or more of a group I body
of compounds soluble in said solvent consisting of the halogenated
sulfonphthaleins and the organic acids having a pKl less than
about four; and (B) one or more of a group II body of compounds
consisting of the aminotriphenylmethanes and their soluble salts,
8-hydroxyquinoline, and the cyanines;
wherein the weight ratio of the group I body of compounds to the
group II body of compounds is more than or about 3 to l and with
the proviso that if the group II compounds consist solely of one
or more aminotriphenylmethanes or their soluble salts, then the
group I compound must be selected from one or more of the group
consisting of oxalic acid, suitable soluble sulfonic acids, and
the tetrahalogenated sulfonphthaleins, and the other organic
acids having a pKl of less than or about 2; and
(3) one or more of the aforesaid group III body of compounds
with one or more of the group I or group II bodies of compounds.
A particularly preferred embodiment of the invention
is a temperature indicator as defined above in which (a) the
group I body of compounds are one or more of the group consisting
of oxalic acid, bromophenol blue, bromothymol blue, chlorophenol
red, bromochlorophenol blue, bromocresol green, 3,4,5,6-tetra-
bromophenolsulfonphthalein, 2-naphthalene-sulfonic acid, tri-
chloroacetic acid, chloroanilic acid, bromophenol red, and
chlorocresol green and (b) the group II body of compounds are
one or more of the group consisting of 5(p-dimethylaminobenzili-
dine)rhodanine, ethyl red, crystal violet, pararosaniline,pararosaniline acetate, 3-ethyl-2-[5-(3-ethyl-2-benzothiazolinyli-
dene)-1,3-pentadienyl~ -benzo-thiazolium iodide, basic fuchsin,
-- 7 --

;Z44;~
8-hydroxy~ulnoline, ethy]. violet, brilliant green, dicyanine A,
pinacyanol chloride, 2-(p-dimethylaminostyryl)-1-ethyl-pyridin-
ium iodide, 3,3'-diethylthiodicarbocyanine iodide, and crypto-
cyanine~ In such a temperature indicator it is preferable that
the weight percentage is from about 0.025 to about 0.05% of the
weight of the solvent and said soluble organic moieties. Pre-
ferred solvents for use in such a temperature indicator are
one or more of the group consisting of ortho-chloronitrobenzene,
ortho-bromonitrobenzene, 1-thymol, 2-naphthol, 2-ethoxybenzamide,
and naphthalene. Furthermore, preferred group I compounds are
those consisting of the halogenated sulfonphthaleins having a pK
of about 2 and a PK2 of about 7 to about 9.
The following constitute particularl.y preferred
organic moieties:
(a) a mixture of bromochlorophenol blue and ethyl red;
(b) a mi.xture of bromochlorophenol blue and ethyl violet;
tc) a mixture of bromophenol blue and basic fuchsin;
(d) a mixture of bromophenol red and brilliant green;
(e) a mixture of bromochlorophenol blue and pinacyanol
chloride;
(f) a mixture of 3,3'-diethylthiodicarbocyanine iodide and
bromocresol purple;
(g) a mixture of 3,3'-diethylthiodicarbocyanine iodide and
bromophenol blue;
(h) a mixture of pinacyanol chloride and 3,4,5,6-tetra-
bromophenolsulfonphthalein;
(i) a mixture of pinacyanol chloride and bromocresol purple;
(j) a mixture of ethyl red and bromochlorophenol blue;
(k) a mixture of pinacyanol chloride and chlorocresol green;
(1) pinacyanol iodide;
(m) .guinaldine red;
(n) 1,1-diethyl-2,21-cyanine iodide;
-- 8

(o) a mixture of chlorophenol blue and ethyl red;
(p) a mixture of bromophenol blue and ethyl red;
(q) a mixture of chlorophenol red and ethyl red;
(r) a mixture of e-thyl red and 3,4,5,6-tetrabromophenol-
sulfonphthalein;
(s) a mixture of ethyl red and bromophenol red;
(t) a mixture of pinacyanol chloride and bromochlorophenol
blue;
(u) a mlxture of ethyl red and bromocresol purple;
(v) a mixture of crystal violet and bromophenol blue;
(w) a mixture of bromochlorophenol blue and brilliant green;
(x) a mixture of naphthalene sul:fonic acid and ethyl
violet;
(y) a mixture of naphthalene sulfonlc acid and crystal
violet;
(z) a mixture of naphthalene sulfonic acid ana ethyl red;
(aa) a mixture of trichloroacetic acid and cryptocyanine;
(ab) a mixture of trichloroacetic acid and ethyl violet;
(ac) a mi~ture of 3-ethyl-2-r5-(3-ethyl-2-benzothiazolinyl-
idene)-1,3-pentadienyl3 -benzothiazolium iodide and
trichloroacetic acid;
(ad) a mixture of chloroanilic acid and basic fuchsin;
~ae) a mixture of chlorophenol red and dicyanine A;
(af) a mixture of chlorophenol red and cryptocyanine;
(ag) a mixture of bromochlorphenol blue and dicyanine A;
(ah) a mixture of 5-p-dimethylaminobenzylidine rhodanine
and dicyan.ine A;
(ai) a mixture of 5-p-dimethylaminobenzy]idine rhodanine
and cryptocyanine.
The composition of matter is used to saturate an
a~rbent layer formed of a porous matrix such as filter paper,
non-woven polyester, and other well~known materials of this nature..
_ g

æ
The absorbent layer containing the temperature
indicating composition of matter is then placed on a paper
backed foil, such as aluminum foil, and covered with a trans-
parent cover for both protecting the absorbent layer and allowing
one to view the layer ~hen the device is attached to a steam
line or other object whose temperature is to be monitored.
A layer of adhesive is placed over the assembly and
another layer of paper backed foil is placed over the layer of
adhesive, care being taken to assure that a viewing area is
present in the over layers to permit a reading of the composition.
Fig. 1 is a top view of a temperature indicator of
the present invention;
Fig. 2 is a bottom view o a temperature indicator
of the present invention; and
Fig. 3 is a side view of a temperature indicator of
the present invention taken along line 3-3 of Fig. 1.
A representative temperature indicator is shown in
the attached figures showing a separated side view of the
temperature indicator of the present invention wherein 12 is a
layer of paper backed foil, e.g., aluminum foil, wherein 12A is
one layer of the paper-backed foil, e.g., paper and 12B represents
the other layer, e.g., aluminum; 15 is a layer of adhesive, e.g.,
a silicone adhesive; 17 is a transparent tape functioning as a
cover; 22 is an absorbent layer con~aining the temperature
indicating composition; 25 is also a layer of paper backed Eoil,
e.gO, aluminum foil, wherein 25A is one layer of the paper-
hacked foil, e.g., aluminum, and 25B represents the other layer,
e.g., paper; and 36 is also a layer of adhesive such as silicone
adhesi~e for attaching the temperature indicator to a steam line
or the like. It is necessary that the configuration of 15, 17,
and 25 form an airtight area for the absorbent layer 22 and the
temperature indicating composition contained thereon to allow
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z~
-the temperature indica-tor to be used a number of times.
The paper backed ~oil is used to permit the temperature
indicator to be used at the contemplated temperatures ofoperation~
and material of -this type is available from the Gravure Flex
Packaging Corp., o~ South ~Iackensack, New Jersey. Materials
performing an equivalent function are equally useful in place of
the paper backed foil.
The layer of adhesive is used to assure an air tight
bond between the transparent cover tape 17, the absorbent layer
containing the temperature indicating composition 22, and the
pa!per backed foil 12 and 25. The second adhesive layer 36 allows
one to readily attach the temperature indicator to the steam
line or other object whose temperature is to be monitored. A .
representative adhesive for either layer is a silicone adhesive
such as Densil* 2079 available from the Dennison Company of
Framingham, Massachusetts.
The transparent cover tape has to have a strength
sufficient to permit continued use of the temperature indicator
and any heavy duty heat resistant plastic can be used. A
typical material is a polyimide tape optionally containing its
own silicone adhesive sold as Kapton* material ~5413 available
from the 3M Company of St. Paul, Minnesota.
The absorbent layer can take the form of a variety of
products, the most readily available material being paper and
a preferred embodiment being filter paper such as a filter paper
disc available from Schleicker and Schnell, Inc. of Keene, New
Hampshire. Any substrate having adequate absorbency to permit
saturation thereof with the temperature i.ndicating composition
can be used.
The temperatures contemplated for monitoring by the
temperature indicator of the present invention can range from
about 30C to about 150C, the temperature being calibrated
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4~Z
depending upon the temperature the user wishes to monitor. The
manner of adjustmen-t of the compositions is more fully explained
in the Hof and Ulin application Serial No. 313,986.
The following examples represent various embodiments
of the invention.
_AMPLE I
A solution consisting of O.OlO grams of bromochloro-
phenol blue and 0.002 grams of ethyl red dissolved in 4.90 grams
of ~,a'-dichloro-p-xylene was prepared by heating the mixture to
~150C. Strips of filter paper were saturated with the dark red
solution and allowea to cool to room temperature. Small discs
cut from the treated strips were placed in an aluminum pan and
covered with a piece of 3M transparent polyimide film. The
aluminum pan was then heat sealed to a larger strip of the same
type of aluminum which contained a hole that was slightly smaller
than the disc. This device was attached to the outside surface
of a steam pipe and the yellow "window" turned dark red when the
steam temperature was 97 to 103C. When the temperature was
allowea to cool to 95C, the yellow color returned.
EXAMPLE II
A number of solutions containing the same concentrations
of bromochlorophenol blue and ethyl red in different solvents were
prepared and the colors of their solid and liquid phases checked.
The results of these tests are given below.
Color
Solvent Solid Liquid
2-naphthol gold dark red
m-toluic acid burnt orange cloudy red
p-toluic acid gold red
succinic anhydride yellow red
benzoic acid burnt orange purple red
Each of these mixtur~s could be recycled through the solid-liquid-
solid phases and each time give the listed colors.
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EXAMPLE III
In this example, various combinations of Group I and
Group II compounds (set out in the table below) were mixed in
succinic anhydride.
Solutions containing 0~010 g of a Group I compound and
0.002 g of a Group II compound in succinic anhydride as a solvent
were prepared and used to form a temperature indicator similar
to that prepared in Example I. The colors of the solid and
liquid states and the temperature range at which the color change
in each device were determined and appear in the table below.
Group I/Group IIColor Range _ Color_
rA~binaL}~ _Temp ~ Solid Li
naphthalene sulfonic 117 to 146 burnt orange dark
acid/ethyl violet green
naphthalene sulfonic 119 to 143 yellow purple
acid/~uinaldine red red
naphthalene sulfonic 117 to 152 burnt oranye dark
acid/ethyl violet green
Each temperature indicator was passed through several solid-liquid-
solid cycles and the phase colors appearing above were obtained
each time.
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