WO2000070412A1

WO2000070412A1 - Timing device

Info

Publication number: WO2000070412A1
Application number: PCT/US2000/005962
Authority: WO
Inventors: Steven T. Adamy; Francis R. Cala
Original assignee: Church & Dwight Co., Inc.
Priority date: 1999-05-14
Filing date: 2000-03-07
Publication date: 2000-11-23
Also published as: CA2368263A1; US6269764B1; AU3619000A

Abstract

A timing device for visually determining the passage of a preselected period of time including an inverted U-shaped tube (2) having opposed ends with at least one of the opposed ends having a reservoir (10a or 10b) for storing a reactant or an indicator, transport means (12) extending from the reservoir (10a or 10b) to the other of the opposed ends of the tube (2) for transporting at least one of the reactant or the indicator until they contact each other, a reactant, and an indicator which when in contact with the reactant via the transport means (12) emits an observable change in a property wherein the minimum length of the period of time corresponds to the time it takes for the reactant and indicator to contact each other.

Description

TIMING DEVICE

Field of the Invention

The present invention is generally directed to a timing device for visually

determining the passage of a preselected period of time which is applicable to a wide

variety of consumer products, especially for products which have an extended shelf or

use life and for which it is desirable to know when the product must be replaced or

rejuvenated. The timing device can be attached to or incorporated in typical packaging

employed for consumer products.

Background of the Invention

Consumer products including food products, cleaning products, deodorizers and

the like have a shelf life determined by the length of time the components of the product

resist change to environmental influences. For example, food products have a given

shelf life based on their ability to resist chemical or physical changes due to contact with

air, heat and other influences in the environment. Many consumer products are date

stamped to provide the user with an indication of the shelf life of the product. The shelf

life may be relatively short such as a few days or may be relatively lengthy such as a

few months. Date stamping of consumer products provides the user with some

indication when the product may no longer be useful for its intended purpose. Quite often, date stamps are printed inconspicuously on the product package.

It is sometimes difficult to read the date stamp and in some cases even to find the date

stamp because it may be printed anywhere on the package. Date stamping is

particularly problematic for products which have a relatively long shelf life because such

products tend to get stored in an obscure recesses of a storage area, such as a food

cabinet or refrigerator. If the product is not used often, the consumer is often unaware

that the expiration date is shortly forthcoming or has even passed.

There have been attempts to provide a visible indication of when the useful life

of a product has expired. So called "life time indicators" are employed for food products

such as disclosed in U.S. Patent Nos. 2,671 ,028; 3,751 ,382; and 3,942,467. These

indicators typically work through chemical reactions initiated or increased in rate by

exposure to high temperatures. Other lifetime indicators rely on diffusion of a

component through a traditional wick or membrane as disclosed in U.S. Patent Nos.

3,414,415; 3,479,877 and 3,768,976, each of which is incorporated herein by reference.

Examples of such products include, for example, the Oral-B toothbrush indicator

which is based on the diffusion of a dye out of the bristles. When the color of a select

group of bristles disappears, the user is aware that the toothbrush may or should be

discarded and replaced. Another example is the Glade Neutralizer which is a

deodorizer product having a timer based on the evaporation of a solvent from a polymer

gel and subsequent shrinkage of the gel. The timing indicators mentioned above suffer from one or more disadvantages

which makes their universal applicability to a wide range of packaged products

problematical. Such disadvantages include a) the timing mechanism is part of the

product (e.g. a deodorizer) and is therefore limited to employment with that product or

that class of products, b) the timing mechanism is inaccurate or cannot be controlled

to accommodate a wide range of product shelf lives, c) the timing mechanism is

expensive and/or d) has a limited range of measurement.

It would therefore be an advance in the art of providing visible indicators for

determining when a product should be replaced or rejuvenated if a cost efficient and

effective shelf life indicator could be provided which provides a clear and distinct visible

indication of when a product should be replaced or rejuvenated. It would be a further

advance in the art if a shelf life indicator could be provided which enables the consumer

to see how much time is remaining for the shelf life of the product which indication is

accurate and clearly visible.

Summary of the Invention

The present invention is generally directed to a shelf life indicator hereinafter

referred to as a "timing device" for determining the remaining shelf life of a product and

visually displaying the same which has applicability to a wide range of consumer

products and packages containing the same. The timing device can be applied to products which have a relatively short shelf life (e.g. dairy products including milk) and

products which have a fairly long shelf life such as canned vegetables.

In a particular aspect of the present invention, there is provided a timing device

for determining and visually displaying the passage of a preselected period of time

comprising:

a) an inverted U-shaped tube having opposed ends with at least one of the

opposed ends having a reservoir for storing a reactant or an indicator;

b) transport means extending from the reservoir to the other of the opposed

ends of the tube for transporting at least one of the reactant or the indicator until they

contact each other;

c) a reactant; and

d) an indicator which when in contact with the reactant via the transport

means emits an observable change in a property wherein the minimal length of the

period of time corresponds to the time it takes for the reactant and indicator to contact

each other.

Methods of employing the device, packages employing the device and methods

of manufacturing the device also constitute a part of the invention set forth herein. Brief Description of the Drawings

The following drawings in which like reference characters indicate like parts are

illustrative of embodiments of the invention and are not intended to limit the invention

as encompassed by the claims forming part of the application.

Figure 1 is a front elevational view of a first embodiment of the inverted U-

shaped tube which is employed as part of the timing device of the present invention;

Figure 2 is a front elevational view of the embodiment shown in Figure 1 showing

contact of the reactant and indicator;

Figure 3 is a front elevational view of the embodiment of Figure 1 with contact

of the reactant and indicator occurring between the respective reservoirs;

Figure 4 is a front elevational view of another embodiment of the invention in

which the wicking material is impregnated with an indicator;

Figure 5 is a front elevational view similar to Figure 4 in which the timing device

is marked with the indicia indicating the incremental passage of time; Figure 6 is a front elevational view of another embodiment of the invention in

which one of the legs of the timing device is longer than the other of the legs;

Figure 7 is a perspective view of the timing device of Figure 6 contained with a

product package with the entire timing device visible;

Figure 8 is a perspective view of the timing device of Figure 6 contained with a

product package with spaced apart portions of the timing device visible;

Figure 9A is a side view of a portion of a timing device containing a wicking

material with a uniform profile;

Figure 9B is a side view similar to Figure 9A with the wicking material having a

non-uniform profile;

Figure 9C is a side view of another embodiment of a wicking material having a

non-uniform profile; and

Figure 10 is an embodiment of the timing device of the present invention

employing a solid reactant or indicator. Detailed Description of the Invention

The present invention is generally directed to a timing device for visually

determining the passage of a preselected period of time in which the timing device has

particular applicability to visually indicating the remaining shelf life of a product,

especially consumer products such as food products and household products. The

main component of the timing device is an inverted U-shaped tube which contains two

components, a reactant and an indicator as more fully described hereinafter. Contact

of the reactant and indicator directly or indirectly produces a visible change in at least

one property, preferably a color change which can indicate that the product should be

replaced or rejuvenated, the amount of time which has passed since the product was

used, and/or the amount of time remaining before the product must be replaced or

rejuvenated. Of particular importance to the present invention is the manner in which

the reactant and indicator come into contact with each other. Control over when the

reactant and indicator come into contact and where in the timing device they come into

contact provides the timing device with the means by which the above-mentioned time

periods can be realized.

A first embodiment of the inverted U-shaped tube is shown in Figure 1. The

inverted U-shaped tube 2 (hereinafter "Tube") is comprised of a pair of spaced apart

and parallel leg portions 4a and 4b connected to each other through a curvilinear central portion 6. The opposed leg portions 4a and 4b and the central portion 6 thereby

define a continuous passageway 8.

Each of the leg portions 4a and 4b have a corresponding reservoir 10a and 10b

at the respective ends of the leg portions 4a and 4b. At least one of the reservoirs will

contain a reactant and the other of the reservoirs may contain an indicator as explained

in more detail hereinafter.

In one embodiment of the invention, the reactant is contained within one of the

reservoirs and the indicator is contained within the other of the reservoirs 10a and 10b.

In accordance with the present invention, there is provided a means for transporting at

least one of the reactant and the indicator so that they may contact each other and

thereby cause a visible change in property (e.g. a color change) which is an indication

of the passage of time corresponding to all or a portion of the shelf life of a product.

The preferred transportation means represented by 12 in Figure 1 is a porous

material, most preferably a wicking material which can absorb the reactant and/or the

indicator and allow the reactant and/or indicator to pass therethrough.

The preferred wicking materials are those selected from the group consisting of

woven fabrics, non-woven fabrics and combinations thereof. What is particularly

important for the wicking material is to enable the reactant and/or indicator to move therethrough and travel at least a portion of the distance from one reservoir to another.

The distance of travel must be sufficient to enable the reactant and indicator to contact

each other and thereby react producing a visible change in a property such as a color

change.

The time it takes for a liquid to pass through a wicking material is dependent on

how well the liquid wets the material. The employment of polar liquids and wicking

materials of lower polarity generally result in longer wicking times. Polar liquids and

polar wicking materials generally result in a timing device where the passage of the

liquid is more rapid (i.e. shorter wicking times).

Specifically preferred wicking materials include polyesters, polyacrylates,

polyacrylamides, polypropylene, polyethylene terephthalate and copolymers thereof,

cellulosic materials (including but not limited to natural or synthetic cotton, wood, paper

and cellulosic polymers), wool, fiberglass, silica gel, ceramics and combinations thereof.

Low polarity wicking materials include polypropylene and polyethylene

terephthalate. Relatively high polarity wicking materials include paper, cotton, wool and

silica gel. The polarity of the wicking material can be altered and hence the time of

travel of the liquid therethrough by producing blends of low and high polarity wicking

materials. An example of such a blend is the combination of polyethylene terephthalate and cotton which are typically made by cross linking the hydroxyl groups of the cotton

with reactive functional groups of the polyethylene terephthalate.

The density of the wicking material may be a factor in controlling the rate of

absorption of the reactant and/or indicator. Generally, the denser the wicking material,

the slower the rate of adsorption. By selecting a suitable wicking material and density

thereof, one is able to control the rate at which the reactant and/or indicator proceeds

through the wicking material to enable the reactant and indicator to come into contact

with each other and thereby cause a visible change in properties.

The physical structure of the wicking material also can influence the rate at which

a fluid passes through the timing device. For example, fluid flow can be affected by the

type of weave and whether the wicking material has a uniform profile (e.g. having a

uniform circular cross-section) or has a non-uniform profile such as a corrugated

structure or combinations thereof.

The Tube 2 as shown in Figure 1 can be fabricated from any number of materials

including plastics and glass. It is preferred that the material used to construct the Tube

2 be unbreakable to prevent injury to the consumer. Preferred materials are plastics

including, for example, polyethylene and polyethylene terephthalate. The Tube 2 must enable the user to observe a color change or other change of

property that occurs within the tube. Thus, the term "clear" as used herein means that

the Tube can be transparent or translucent, but not opaque. The Tube 2 itself may be

colored so long as the color change taking place within the tube can be observed by

the user.

The reactant and indicator may be selected from solids, liquids or gases so long

as the reactant and indicator are able to contact each other. Liquid reactants and

indicators are preferred because gaseous reactants and indicators tend to travel over

a relatively short period of time because they more readily diffuse through the Tube 2

and are more difficult to control using the wicking material present therein. Where

desirable, one, but not both of the indicator and reactant may be a solid.

The reactant and indicator are selected so that when in contact with each other

there is a visible change of properties such as a color change. The reactant can be

selected from acids, bases, oxidizing agents and reducing agents. The indicators are

those materials which when in contact with the reactant cause the change in properties

which are visible to the user. For example, indicators include litmus compounds, methyl

orange, bromocresol green and congo red.

The change in property which results in a change observable by the user may

be from the direct interaction of the indicator and reactant or through an intermediary substance. Direct interaction indicators are those which change color through direct

contact with the reactant. Examples of direct indicators are so-called redox indicators

such as thymoiindolphenol and neutral red. Thymoiindolphenol is colorless in its

reduced form. Upon contact with a suitable oxidizing agent (e.g. Fe⁺³),

thymoiindolphenol is oxidized and thereby turns blue.

Neural red is likewise colorless in reduced form. When oxidized in the presence

of a suitable oxidizing agent, neutral red turns red. Other redox reactions may be

employed to effect a visible color change including the conversion of Cr0₂ ^" (green) to

Cr0₄-² (yellow).

The above-mentioned redox systems are examples of direct interaction systems.

Such systems produce a change of property by direct reaction of the reactant and

indicator.

In some reactant-indicator systems, it is possible to extend the time before the

reactant and indicator react to produce a change of property by employing a scavenger

for one of them. For example, a reactant (Fe⁺³), scavenger (Cu⁺¹) and indicator (e.g.

thymoiindolphenol) are contained within the timing device. Before the indicator can

undergo a color change, the reactant first reacts with the scavenger. Alternatively,

another method of obtaining a further delay is to initiate a series of reactions such that

a first reactant and a co-reactant produce a first intermediate. The first intermediate can either react with the indicator or with a second co-reactant to produce second

intermediate which second intermediate reacts with the indicator to produce a color

change. Any number of intermediary reactions and intermediates may be employed as

desired.

Other reactant-indicator pairs and scavengers used therewith are known and

available such as the employment of a system including Ti⁺² (indicator), Fe⁺³

(scavenger) and neutral red (indicator).

In another reactant-indicator system, the reactant may be water which induces

a color change from a reactant which is an anhydrous compound. For example, cobalt

chloride is an anhydrous compound which is blue. Upon contact with water (reactant),

the cobalt chloride converts to the hydrated form which has a pink color. Other

anhydrous compounds which are suitable for use in the present invention would be

known to those of ordinary skill in the art.

In the embodiment shown specifically in Figure 1 , there is employed two

reservoirs 10a and 10b. The reactant may be contained in the reservoir 10a and the

indicator may be contained in the reservoir 10b. The wicking material 12 is contained

within the passageway 8 extending from the reservoir 10a to the reservoir 10b. The

selection of a suitable wicking material will enable at least one of the reactant and

indicator to travel up the wicking material until the reactant contacts the indicator. If both the reactant and indicator travel through the wicking material, they will meet at

some location in the wicking material depending on the relative rates of absorption of

the reactant and indicator. Thus, the visible color change will take place at some point

along the wicking material and the time it takes for that visible color change to take

place is the period of time coinciding with the desirable shelf life of the product. If

desired, a portion of the tube may be opaque or hidden so that a visible window area

is present at a different location than where the reactant and indicator initially react. If

the indicator is not absorbed by the wicking material then the color change will take

place in the reservoir 10b after the reactant has traveled the full distance through the

wicking material from the reservoir 10a and to the reservoir 10b.

For longer periods of time, the reactant (which can be a solvent) may be a liquid

or in solution and the indicator may be solid. The tube is opaque except for a window.

The liquid traverses the tube to reach the solid indicator, dissolves the indicator, and

draws the dissolved indicator back along the wicking material until the window portion

of the tube is reached and a visual observation can be made.

The employment of a reactant and indicator pair provides a fixed period of time

before a color change takes place depending on the type and density of the wicking

material. Quite often, it is desirable to modify the rate at which the reactant and/or the

indicator travel through the wicking material in order to provide a longer or shorter shelf

life measurement which may be accomplished by adding a viscosity modifying agent. The employment of a viscosity modifying agent is dependent in part on the recognition

that when the reactants and/or indicators are liquids they typically move through the

wicking material in opposite directions which will impede the forward progress of each

flow. Furthermore, the viscosity of the reactant and/or indicator will have an effect on

the rate of movement of the same through the wicking material. As previously indicated

if a modification of the rate of movement is desired a viscosity modifying agent may be

used.

In accordance with the present invention, a viscosity modifying agent may be

added either to the reactant or to the indicator or to both. The viscosity modifying

agent, depending on its viscosity, can be used to speed up or slow down the rate of

travel of the reactant and/or indicator. The slowing down of the travel time is desirable

when the shelf life of the product is relatively long. The speeding up of the travel time

is desirable for those products having a relatively short shelf life.

Viscosity modifying agents for use in the present invention are desirably

compatible with the other components (i.e. reactants and indicators) in that they do not

cause any change in the composition of the components or the manner in which they

react with each other. Another desirable property of the viscosity modifying agents is

that they are able to be absorbed and passed through the wicking material without

adversely affecting the reactant and indicator. Still further, it is desirable that the

viscosity modifying agent be nontoxic, particulary when associated with products used by consumers. Typical examples of viscosity modifying agents for use in the present

invention include water, glycerine, alkylene glycols (e.g. propylene glycol) and

combinations thereof.

The amount of the reactant, indicator, and optional viscosity modifying agent will

vary. The amounts selected for each of the components are made to ensure a visible

change in property after a desirable preselected period of time (i.e. the length of the

time of the shelf life of the product). The amount of each of these components should

be sufficient to travel through the wicking material for the estimated distance of travel

to have contact of the reactant and indicator. This represents a minimum amount of the

components to achieve the desired time period measurement. More than the minimum

amount of each component can be used to ensure a proper reaction at a desirable

location within the timing device. Generally, the amount of the reactant is at least

0.01 % by weight and most typically from about 0.01 to 5.0% by weight, based on the

total weight of the materials of the reactant solution. The amount of the indicator is

typically at least 0.01 % by weight, most typically within the range of from about 0.01 to

0.5% by weight and the amount of the viscosity modifying agent, if necessary, may

approach 100% by weight of the indicator and/or reactant solution and is typically in the

range of from about 25 to 75% by weight based on the weight of the respective solution.

In one embodiment of the invention, as previously described and as shown in

connection with Figure 2, the reactant contained within a reservoir (e.g. 10a) travels the entire length of the wick until it reaches the reservoir (e.g. 10b) containing the indicator

at which time a color change occurs. The time it takes for the reactant to travel through

the wick and into the reservoir 10b containing the indicator corresponds to the desired

shelf life of the product and when the color change occurs the user knows that the

product should be discarded or rejuvenated. In special "window" embodiments, the

time period and the initial reaction time are not the same; rather the desired time period

is for a color change to occur at a particular location along the inverted "U"-shaped

tube.

In another embodiment of the invention as shown in Figure 3 both the reactant

contained in the reservoir 10a and the indicator contained in the reservoir 10b travel

through the wicking material and eventually contact each other at some point within the

passageway 8 of the device 2. By suitably selecting reactants and indicators as well

as the type and density of the wicking material, and optionally a viscosity modifying

agent, the point of contact of the reagent and indicator and their time of travel can be

accurately predicted and controlled. As shown specifically in Figure 3, the point of

contact of the reactant and indicator is about midway of the total length of the

passageway and when a color change is observed at the point of contact, the product

should be discarded or rejuvenated by the user. Where desired, time periods

corresponding to periods other than the initial contact point between the reactant and

the indicator may also be selected by utilizing a substantially opaque tube and a

window enabling visible observations at a preselected position along the tube. The desired time period would then correspond to a visible color change visible in the

"window" region of the tube.

The embodiments of the present invention as described in connection with

Figures 1 -3 provide for the movement of the reactant alone or the movement of both

the reactant and the indicator through the wicking material and eventual contact

causing a visible color change. It will be understood that in accordance with the present

invention, the reactant may remain within the reservoir 10a while the indicator moves

from the reservoir 10b through the wicking material over the entire length of the

passageway 8 into the reservoir 10a where a reaction occurs causing a color change.

In all of these embodiments (Figures 1 -3) the occurrence of a color change coincides

with the useful shelf life of the product. When the color change occurs, the product is

discarded or rejuvenated.

However, the present invention is applicable to the employment of a color

change as a continuous indication of the passage of time so that the user can readily

identify how much time has passed since the product has been used and how much

time remains until the product must be discarded. In this embodiment of the invention,

it is desirable to place either the reactant or the indicator throughout the wicking

material and let the other of the reactant and indicator be absorbed through the wicking

material from one of the reservoirs causing a continuous color change from one

reservoir to the other. Referring to Figures 4 and 5, there is shown the device 2 of the present invention having a wicking material 12 extending from one leg portion 4a to the

other leg portion 4b. Within the reservoir 10a is, for example, a reactant. The wicking

material 12 is impregnated with one of the reactant or indicator (e.g. the indicator). The

wicking material 12 has the indicator impregnated therein from just above the reservoir

10a containing the reactant all the way to the opposed end of the timing device 2. As

the reactant is absorbed by the wicking material, the reactant contacts the indicator

imbedded in the wicking material at a point 14 lying just above the reservoir 10a. As

the reactant continues to move through the wicking material, a simultaneous color

change occurs because of the continuous contact of the reactant and the indicator.

Thus, the embodiment of Figure 4 measures the product life from the time of its use

until the passage of a time period corresponding to the useful shelf life of the product.

As specifically shown in Figure 5 the embodiment of Figure 4 can be employed

to measure the passage of time and provide the user with the remaining shelf life of the

product.

For example, if a product has a useful shelf life of approximately five weeks, the

timing device of the present invention based on the embodiment shown in Figure 4 may

be constructed as shown in Figure 5. The timing device may be marked with weeks 1-5

(i.e. wk1 =the first week; wk2=the second week, etc). Thus, as the color change

commences from point 14 (the beginning of use of the product) and passes from point

14 to the marker indicating week one (wk1 ) the user will know that one week has passed since the product was used and about four weeks remain before the product

must be discarded. It will be understood that the timing device can be constructed so

that longer or shorter periods of time may be indicated depending on the type of

reactant and indicator, the type and density of the wicking material, and the optional use

of a viscosity modifying agent.

In a preferred embodiment of the present invention, one of the reservoirs lies

below the plane of the other of the reservoirs. This system provides more efficient

travel of the reactant or indicator and a more accurate indication of the shelf life of the

product. Referring to Figure 6, the timing device 2 has one of the leg portions 4a

shorter than the other of the leg portions 4b so that the reservoir 10a lies completely

above the reservoir 10b. Thus, the reactant contained in reservoir 10a has a shorter

distance to travel to pass through the leg portion 4a into the leg portion 4b than in the

embodiments shown in Figures 1-5. The difference in length of the two legs, "delta",

is one factor controlling the efficiency of the transfer of fluid from one leg to the other.

By increasing delta either by increasing the downward leg length 4a or by shortening

the upward leg length 4b, or both, the siphoning effect, and hence the efficiency of the

movement of liquid from 10a to 10b is enhanced.

The timing device of the present invention can be contained within a packaging

or housing which has one or more ports or windows that enables the user to view the

device to observe a color change at one or more locations. Referring to Figure 7, there is shown an embodiment of the timing device shown

in Figures 5 and 6 contained within a housing 20 of a package 22 which contains a

consumer product. The housing 20 provides sufficient space to house the timing device

2. The housing 20 has a front face 24 with a clear window 26 enabling the viewer to

view the entire timing device 2. In this embodiment of the invention, the user can view

the entire timing device 2 as discussed above in connection with Figures 1-5. Thus, all

color changes and the location of all color changes can be observed by the user.

In another embodiment of the invention as shown in Figure 8, the package 22

may be provided with a housing 20 in which the front face 24 contains one or more

ports or windows 28 which shows periodic color changes through the window indicating

the passage of a fixed period of time such as one week or one month. If only one

window is used, it should be at the point that there is a final color change indicating that

the product needs to be replaced or rejuvenated. The employment of multiple windows

28 enables the user to periodically observe how much time has passed and how much

time remains of the product shelf life. In the specific embodiment of Figure 8, there are

six windows with the first two windows indicating a color change. If each window was

indicative of the passage of one week of time, then the product would have been used

for two weeks with about four weeks remaining of the product shelf life.

The timing device 2 of the present invention can be affixed to a product by

adhesive or the like or can become prepackaged with the product as indicated in the embodiments of Figures 7 and 8. In some cases, it is desirable to package the reactant

and indicators in the respective reservoirs within a breakable container which can be

broken by pressure applied to the user. Such containers include capsules made of a

variety of materials including gelatins and the like. The breakable capsules enable the

user to commence the start of the product life and thereby disregard that the period of

time from manufacture to purchase by the user.

The wicking material employed in the timing device of the present invention may

be arranged in a uniform profile or a non-uniform profile. The term "uniform profile"

shall mean that the cross-sectional area and shape of the wicking material is the same

throughout the length thereof. The term "non-uniform profile" shall mean that the cross-

sectional area and shape of the wicking material is not the same throughout the length

thereof.

Referring to Figure 9A there is shown a uniform profile wicking material 30

having a uniform diameter and shape throughout the length of the wicking material.

Figure 9B shows a non-uniform profile in which the wicking material 40 has a center

portion 42 having a smaller cross-sectional area than the opposed legs 44 thereof.

In another embodiment of a non-uniform profile, the wicking material may have

a corrugated profile. Referring to Figure 9C the wicking material 50 includes a series of peaks 52 and valleys 54 so that at any one location the cross-sectional area and/or

shape is different from another location along the length thereof.

As previously indicated the timing device may employ a reactant or indicator

which is comprised of a solid material. One such embodiment is shown in Figure 10.

Referring to Figure 10, a timing device 2 is packaged in a manner similar to the

embodiment shown in Figure 7. In particular, the package 22 has a front face 24 which

can expose all or part of the timing device 2 through a window 26. A reservoir 10b

contains a solid indicator (e.g. cobalt chloride) while a reservoir 10a contains a liquid

reactant (e.g. water). Water travels from the reservoir 10a to the reservoir 10b to cause

a color change (e.g. from blue to pink) which is observable through the window 26.

The time for a color change to occur in the embodiment shown in Figure 10 will

in part be dependent on the time it takes the reactant (e.g. water) to reach the solid

indicator (e.g. cobalt chloride). It will be observed that contact of the liquid reactant and

solid indicator will result in the formation of a solution in the reservoir 10b. Due to

capillary action, and concentration gradients, the solution (which will have a pink color

in the example mentioned above) will migrate toward the reservoir 10a. As a

consequence, it is possible to place a window along the path of the wicking material to

observe the "pink" colored solution. Such a window is shown in Figure 10 by numeral

60. Thus the length of the period of time can be extended because the liquid indicator

must first travel from reservoir 10b to 10a to cause a color change therein and then for an additional period of time until the colored solution in the reservoir 10a reaches the

window 60 where it is observed by the consumer. Alternatively, solid indicator may be

placed in reservoir 10b and liquid reactant may be placed in reservoir 10a.

Example 1

A timing device of the type shown in Figure 6 was constructed by inserting into

a U-shaped tube. Grade 3 chromatographic paper obtained from Whatman, Inc. of

Clifton, New Jersey may serve as the wicking material. Reservoirs were made from the

bulbs of 3 ml disposable pipettes obtained from Becton Dickinson Co. of Franklin

Lakes, New Jersey.

A reactant solution was prepared by combining 9.80 weight % of deionized

water, 88.24 weight % of glycerine and 1.96 weight % of glacial acetic acid. An

indicator solution was prepared by combining 10 weight % of deionized water, 89.95

weight % of glycerine and 0.05 weight % of litmus. The reactant solution was clear

while the indicator solution was blue.

In order to activate the timing mechanism, 1.5 ml of the indicator solution was

placed in the indicator reservoir and 1.5 ml of the acidic solution was placed in the

reactant reservoir. The U-shaped wick was then placed in the reservoirs until each end of the wick touched the bottom of the reservoirs. The entire assembly was then

wrapped in a covering of plastic film.

The timer duration was noted as the time it took the indicator reservoir to turn

from blue to red. Multiple samples were tested in this matter at ambient temperature

(typically at 68-70°F) or in a thermostatic chamber which maintained a constant

temperature of 80°F and a relative humidity of 80%. The results are shown in Table

1.

Table 1

Samples Duration (Room Temp.) Duration (80 °F/80% Rm

Group 1 42±2 days 36±2 days

Group II 38±2 days 35±2 days

As shown in Table 1 , the duration of the respective samples at room temperature

was fairly consistent and provided a fairly accurate means of measuring shelf life of the

product. It was noted that when the temperature and relative humidity increased

significantly, there was a reduction in the time it took for the reactant to contact the

indicator. Example 2

A timing device of the type shown in Figure 6 using Whatman Grade 17

chromatography paper was employed to measure the effective life of a box of baking

soda used as a deodorizer within a cool environment such as maybe found in a

refrigerator or freezer.

An indicator solution was prepared containing 7.50% by weight of deionized

water, 67.47% by weight of glycerine, 24.98 weight % of propylene glycol and 0.05

weight % litmus. A reactant solution was prepared containing 7.35 weight % of

deionized water, 66.18 weight % of glycerine, 24.51 weight % of propylene glycol and

1.96 weight % of glacial acidic acid. Several samples of the timing device of the type

shown in Figure 6 were combined with the above-mentioned reactant and indicator

solutions and tested in a refrigerator at 40°F. The timing device showed an average

life of 80±4 days.

Example 3

The process of Example 2 was repeated except that the indicator solution

contained 7.49 weight % of deionized water, 67.43 weight % of glycerine, 24.9 weight

% of propylene glycol and 0.10 weight % litmus. The reactant solution remained the same as in Example 2. This system was tested in the same manner as in Example 2

and the duration of the timing device samples averaged 92±4 days.

Claims

What Is Claimed Is:

1. A timing device for visually determining the passage of a preselected

period of time comprising:

(a) an inverted U-shaped tube having opposed ends with at least

one of the opposed ends having a reservoir for storing a reactant or an indicator;

(b) transport means extending from the reservoir to the other of the

opposed ends of the tube for transporting at least one of the reactant or the indicator

until they contact each other;

(c) a reactant; and

(d) an indicator which when in contact with the reactant via the

transport means emits an observable change in a property wherein the minimum

length of the period of time corresponds to the time it takes for the reactant and

indicator to contact each other.

2. The timing device of claim 1 wherein each of said opposed ends has a

reservoir.

3. The timing device of claim 2 wherein the reactant is initially present in

a first reservoir at one of said ends and the indicator is present in a second reservoir

at the other of said ends.

4. The timing device of claim 1 wherein at least one of said reactant and

said indicator is a liquid.

5. The timing device of claim 1 wherein the inverted U-shaped tube

comprises a pair of legs extending downwardly from the central portion, one of said

legs being of greater length than the other of said legs.

6. The timing device of claim 4 wherein each of said reactant and

indicator is a liquid.

7. The timing device of claim 6 wherein the reactant is selected from the

group consisting of an acid and a base.

8. The timing device of claim 7 wherein the indicator changes color when

contact by the reactant.

9. The timing device of claim 1 wherein the indicator comprises a color

changing compound and a viscosity modifying agent and the reactant optionally

further comprises a viscosity modifying agent.

10. The timing device of claim 9 wherein the viscosity modifying agent is

selected from the group consisting of water, glycerine, alkylene glycols and mixtures

thereof.

11. The timing device of claim 1 wherein the transport means is comprised

of porous material.

12. The timing device of claim 1 wherein the transport means is comprised

of a wicking material.

13. The timing device of claim 1 wherein the wicking material is selected

from the group consisting of woven fabrics, non-woven fabrics and combinations

thereof.

14. The timing device of claim 1 wherein the wicking material is selected

from the group consisting of polyesters, polyacrylates, polyacrylamides,

polypropylene and copolymers thereof, natural or synthetic cellulosic materials,

wood, paper, cellulosic polymers, cotton, wool, fiberglass, silica gel, ceramics and

combinations thereof.

15. The timing of device of claim 12 wherein at least one of the reactant

and indicator are present in the wicking material.

16. The timing device of claim 1 further comprising location means for

identifying a location on the transport means where a desirable observable change

occurs corresponding to said preselected period of time.

17. The timing device of claim 1 wherein the indicator is an anhydrous

compound and the reactant is water.

18. The timing device of claim 1 further comprising a scavenger material.

19. The timing device of claim 18 wherein the reactant reacts with the

scavenger material preferentially to prevent substantial reaction of the reactant with

the indicator until the scavenger material is substantially consumed.

20. The timing device of claim 1 further comprising an intermediary

substance wherein the reactant reacts with the intermediary substance to produce a

second reactant which reacts with the indicator to produce said observable change

of property.

21. The timing device of claim 1 wherein the reactant or indicator is a solid

material.

22. The timing device of claim 1 wherein the other of said reactant or

indicator travels via the transport means to the solid material.

23. The timing device of claim 22 wherein the reactant and indicator

contact each other to produce said liquid exhibiting a change of property, said period

of time including the length of time it takes the liquid to travel a predetermined

distance through the wicking material.

24. A package having on an outer surface thereof a timing device for

timing a preselected period of time corresponding to a product replacement period of

time of a product contained with the package, said timing device comprising:

(a) an inverted U-shaped tube having opposed ends with at least

(b) transport means extending from the reservoir to the other of the

until they contact each other;

(c) a reactant; and

(d) an indicator which when in contact with the reactant via the

transport means emits an observable change in a property, wherein the minimum

length of the period of time corresponds to the time it takes for the reactant and the

indicator to contact each other.

25. The package of claim 24 wherein each of the said opposed ends has a

reservoir.

26. The package of claim 25 wherein the reactant is initially present in a

first reservoir at one of said ends and the indicator is present in a second reservoir

at the other of said ends.

27. The package of claim 24 further comprising location means for

occurs corresponding to said preselected period of time.

28. The package of claim 27 wherein the location means is at least one

window.

29. A method of determining the passage of a preselected period of time

corresponding to the useful life of a product comprising:

(a) attaching to said product or to a package containing said product a

timing device comprising;

(1 ) an inverted U-shaped tube having opposed ends with at least

one of the opposed ends having a reservoir for storing a reactant or an indicator,

and (2) transport means extending from the reservoir to the other of the

opposed ends of the tube,

(b) placing one of said reactant or indicator in the reservoir and the other

of said reactant or indicator at the opposed end remote from the reservoir;

(c) transporting at least one of the reactant or indicator along the transport

means for a sufficient distance so that the reactant and indicator contact each other,

and

(d) observing a change in property of said indicator as a result of said

contact as an indication of the passage of said preselected period of time.

30. The method of claim 29 comprising controlling the rate of flow of at

least one of the reactant and indicator through the transport means.

31. The method of claim 29 comprising selecting a point on said transport

means as a measure of the distance of travel of at least one of the reactant and

indicator corresponding to the preselected period of time.

32. The method of claim 29 wherein the reactant and indicator are

contained within separate breakable containers, said process further comprising

breaking said containers to commence the preselected period of time.