MXPA06007294A - Fibrous materials exhibiting thermal change during use - Google Patents

Abstract

Fibrous sheet materials, such as are useful as facial tissue, bath tissue and paper towels, for example, are provided with chemical agents, such as certain salts, which create a temperature change in the sheet when exposed to a particular stimulant, such as water, for example. These materials can provide a soothing feel to the user, either in the form of cooling or heating, depending upon the particular chemistry involved.

Description

FIBROUS MATERIALS THAT EXHIBIT THERMAL CHANGE DURING USE Background of the Invention The heat and cold are used to transmit calming and healing characteristics to a variety of personal care products. For example, people are very familiar with the use of hot or cold packaging to treat sports injuries or using cold packs to cool the body after exercise. In other products, certain chemicals such as menthol can be used to give the sensation of cooling, even when such sensations are driven by the interaction of the chemical that animates the skin and does not cause a de facto change in the temperature of the body or object. This also requires that the substance is in fact transferred to the skin to produce the desired effect.

Another approach to providing a sense of freshness is the use of a lotion that blends with the contact with the user. Heat fusion causes heat to be removed from the user and used to melt the lotion. Since no change in temperature is associated with the melting process, as the heat is removed from the user, the skin actually cools. While in theory this may provide a means to produce a product that is capable of changing the temperature of the wearer's skin, the temperature at which the lotion melts must be controlled closely.

In addition, the rate at which the lotion melts is slow and an extended period of contact may be required between the user's skin and the lotion. Also, heat fusion tends to be relatively low for these compounds and the change in temperature is minimal, therefore providing imperceptible changes for the user.

A similar approach to cooling is the use of a volatile substance. In this case a volatile fluid is applied to the product in use, the volatile fluid contacts the skin of the user. When the volatile fluid comes in contact with the skin it begins to vaporize. The heat removed from the skin vaporizes the substance causing a cooling on the surface of the skin. While such an approach can produce a significant cooling effect, the problems are significant. Among others are requirements to have a wet product form, environmental problems related to the generation of the volatile organic chemical (VOC) and the need to store the product in a vacuum vessel when it is not used. Additionally these volatile components can be harsh to the skin and can cause itching and other discomforts.

Therefore, there is a need to produce a fibrous sheet that has the ability to provide a sensation of heat or cooling. There is a further need for this sheet to be produced in such a way that it is able to be stored in the dry state, has a low content of volatile organic chemical (VOC) and non-irritating to the skin. There is a further need for this blade to have a relatively low caliber in such a way that it is suitable for cleaning the body. There is a further need for such sheets not to transfer unwanted chemicals to the wearer's skin.

Synthesis of the Invention In general, the invention resides in a product comprising a fibrous absorbent sheet containing one or more chemical agents that react exothermically or endothermically when the sheet is subjected to a non-thermal stimulus externally applied in such a way that the temperature of the sheet Increases or decreases at least 1 degree centigrade or greater.

More specifically, in one embodiment the invention resides in a product comprising an absorbent fibrous sheet containing one or more encapsulated chemical agents that react exothermically or endothermically when the sheet is subjected to sufficient pressure to break the capsules and release the encapsulated chemical agents. .

In another embodiment, the invention resides in a product comprising a fibrous absorbent sheet containing one or more salts that react exothermically or endothermically when the sheet is wetted. Such sheets may incorporate salts within a non-hygroscopic package that It is soluble in water. When the water contacts the capsule containing the so-called salts, the capsule and salts dissolve to create a heating or cooling effect.

In particular, it has been discovered that by incorporating various salts into the fibrous sheets, such are useful as products of tissues, towels or other personal cleansing cloth products, a significant endothermic or exothermic temperature change is provided when the sheets are wetted. Whether the leaf warms or cools depends on the enthalpy of the salt or salt solution being used. When the water is absorbed by the leaf, the salt or salts dissolve and a remarkable temperature change is created. This temperature change occurs within the sheet itself and does not require transfer of an ingredient in the product to the user's skin. The products of this invention can have a wide range of applicability to clean hands, face and body since the change in temperature can be initiated by absorption of body fluids, such as sweat or surface moisture on the skin, for example . Such products may comprise sheets of synthetic and / or natural fibers formed by an air laying or wet laying process, for example. The invention encompasses not only forms of the final product to the user, but also intermediate base sheet materials useful as components for disposable personal care articles and other applications.

In general, the invention resides in a product comprising a fibrous absorbent sheet containing one or more chemical agents that react exothermically or endothermically when the sheet is subjected to a non-thermal stimulus applied externally such that the temperature of the sheet Increases or decreases at least 1 degree centigrade or greater.

More specifically, in one embodiment the invention resides in a product comprising an absorbent fibrous sheet containing one or more encapsulated chemical agents that react exothermically or endothermically when the sheet is subjected to sufficient pressure to break the capsules and release the chemical agents encapsulated In another embodiment the so-called encapsulates are soluble in water in such a way that with the addition of water the encapsulates dissolve and the chemical reaction occurs.

In another embodiment, the invention resides in a product comprising a fibrous absorbent sheet containing one or more salts that react exothermically or endothermically when the sheet is wetted.

For various dry cleaning cloth products, such as facial tissue, bath tissue, or paper towels, for example, upon contact with water the temperature of the sheet will rise or fall depending on the desired effect. For other applications, the sheets according to this invention they can also be used as a sports cleaning cloth, where the sweat absorbed by the product causes the dissolution of a material with an endothermic enthalpy of solution to produce a refreshing effect. They can also be used as a disposable towel, in which as water is absorbed from the body, a salt having an exothermic notch of solution is dissolved to provide an increase in temperature and a feeling of warmth to the body. Other executions of the product include products intended to be used against the body and which will heat or cool the body as body moisture is introduced into the product. For example, a disposable headband or a sweat band can provide a feeling of freshness as used. Another possible application can be in disposable rainwear, where a small amount of rain can allow the passage in the garment allowing the dissolution of a salt with an exothermic heat of solution, thus causing an increase in the temperature of the garment. and providing a feeling of warming to the user.

In the specific embodiments described above, the mechanism for producing the temperature change is due to the enthalpy of solution of the various salts used. However, it is within the scope of this invention to induce the change in temperature by other reaction mechanisms. For example, two chemicals capable of reacting with each one can be applied in discrete locations on the sheet. For example, in a multi-layer sheet, a chemical can be incorporated into the inner layer and the other chemical can be incorporated into one or more of the outer layers of the sheet. When the leaf is dry, the chemicals do not migrate through the leaf and can not contact each one. Therefore, no chemical reaction occurs. However, when water is applied to the leaf, the chemicals can become mobile and can interact with each other within the leaf. The resulting chemical reaction causes an increase or decrease in the temperature of the leaf, depending on the heat of the reaction associated with the specific chemical interaction. Examples of chemical reactions used to provide electrochemical heat sources are described in U.S. Patent No. 5,538,020 issued to Farrier and assigned to R. J. Reynolds Tobacco Company, which is incorporated herein by reference.

Even when in some incorporations the specific change of temperature is induced by the addition of water and the use of salts with very highly positive or negative slots of solution, the cleaning cloth products that produce a temperature change when exposed to an external stimulus In addition to water and where the temperature change occurs via a different mechanism, they are possible. For example, two separate chemicals can be encapsulated and incorporated into the tissue. When the capsules are broken, the chemicals inside the capsules are allowed to mix and a chemical reaction that produces or abs heat causes the temperature to fall or fall. For example, acids and bases can be added to the tissue as separate encapsulated materials. When the tissue is subjected to external working stresses in use, the capsules are broken, thus causing a neutralized reaction with acid base, and the release of heat.

For cleaning cloth products in general, the chemicals used to create the temperature change will be located on the outer surfaces of the cleaning cloth product. In many cases it will be preferable not to cause the chemical to come into contact with the user's skin due to possible skin irritation. There are a variety of means by which chemicals can be incorporated into the products of this invention to minimize the potential for skin contact. If the cleaning cloth product is a product of multiple strata, which have three, four, five or more layers, for example, the chemical or chemicals that produce the temperature change can be located within the stratum or inner strata. When an external stimulus (such as water addition) is applied to the product, a reaction occurs in the stratum or strata chemically treated and the product heats or cools accordingly. The majority of the reaction is contained within the stratum or inner strata with little chemical transfer to the outer strata. In another embodiment, the dry chemical reagent that produces the change The temperature can be encapsulated in a particle that has a water-soluble outer shell. When the water is absd by the product, the outer shell dissolves and the chemical and water will react to produce a change in temperature. In yet another embodiment, the reactive chemical is dissolved or dispersed within the water soluble film sandwiched between two absnt layers. When water contacts the film, the film dissolves, thereby releasing the chemical. As the chemist is released, reacts with water to produce the desired temperature change. In yet another embodiment, the chemical can be applied and absorbed into fibers, such as by soaking the fibers in a solution of the chemical. The fibers are removed from the solution, dried and individualized to form a material of the sponge-like type. The treated foamed pulp fibers may be incorporated in a middle stratum of a multi-stratified product or within a layer of a multi-layered stratum to provide an absorbent product capable of producing the desired temperature change.

The chemicals can be applied to the sheet by any suitable means known in the art. This may include, without limitation: addition as solid particles on the sheet; spraying an aqueous solution of the chemicals onto 1 leaf and subsequently drying the leaf; after treatment of the fibers with salts or other chemicals before drying final; apply microspheres containing chemicals; dip the sheet in a solution of the chemicals followed by drying; apply as a movie, etc.

The amount of chemical applied to the product will depend on the product and the particular chemicals chosen, but they must be sufficient to provide a change in temperature that is noticeable to the user. In terms of absolute value (either an increase or decrease in temperature), the change in temperature may be 1 degree centigrade or greater, more specifically about 3 degree centigrade or more, more specifically about 5 degree centigrade or more, more specifically from 1 degree centigrade to about 10 degree centigrade, even more specifically from about 2 degrees centigrade to about 10 degrees centigrade, and even more specifically from about 3 degrees centigrade to about 6 degrees centigrade. When the enthalpies of solution for salts are used to affect the temperature change, it is advantageous if the enthalpy of salt solution to infinite dissolution is around 2,000 cal / mol or greater at 25 degrees centigrade if cooling is desired and -2,000 cal / mol or less at 25 degrees centigrade if heating is desired. Values of higher enthalpy solution (for cooled) and lower values (for heating), respectively, are advantageous because less salt is required to produce the desired temperature change. Some specific salts useful for purposes of this invention include, without limitation, KCl with? H ° 8 of 4,115 cal / mol, NH4N03 with a? H ° 8 of 6,400 cal / mol, NaNo3 with a? H ° 8 of 4,900 cal / mol, NH4C1 with a ? H 8 of 3,533 cal / mol, CaCl 2 with a? H 8 of -8,102 cal / mol, LiCl with an? H 8 of -8,850 cal / mol, NaC2H302 with an? H 8 of -4,140 cal / mol. The enthalpy values of solution for these and other monovalent salts can be found in the CRC Manual, 72nd edition, pages 5-101.

When deliquescent salts such as calcium chloride or lithium chloride are used, it is necessary to prevent such materials from coming into contact with the humidity of the air before use. Such salts are able to absorb enough moisture from the air to become a solution. As such, the salts will slowly absorb moisture from the air and warm up over time. However, once the moisture balance is reached they are no longer able to heat up with the addition of more water. Air humidity can be prevented from the sheet by the encapsulation of so-called salts as previously described, use of sealed packages, or any other packaging technique generally known in the art to prevent atmospheric moisture from contacting sensitive materials. Smoke until use.

The basis weight of the absorbent fibrous sheets useful for the purposes of this invention may have a basis weight from about 5 grams per square meter to around 200 grams per square meter. For use as a facial tissue or bath tissue, the base weight range can range from about 5 grams per square meter to about 50 grams per square meter. For paper towels and the like, the basis weight can be in the range from about 15 grams per square meter to about 200 grams per square meter.

In addition, the absorbent fibrous sheets useful herein for facial tissue, bath tissue, and paper towels and the like can also be characterized by a leaf volume of about 2 cubic centimeters per gram or greater, more specifically from about 5 cubic centimeters per gram or more. to around 20 cubic centimeters per gram or more. The leaf volume is calculated as the quotient of the caliber (hereinafter defined) of the leaf, expressed in microns, divided by the dry basis weight, expressed in grams per square meter. The resulting leaf volume is expressed in cubic centimeters per gram. More specifically, the caliber is measured as the total thickness of a stack of ten representative sheets and dividing the total thickness of the stack by ten, where each sheet within the stack is placed with the same side up. The caliber is measured in accordance with the T402 test methods of the Technical Association of the Pulp and Paper Industry (TAPPI) "Standard Conditioning and Test Atmosphere for Paper, Cardboard, Pulp Hand Sheets and Related Products", and the T411 om-89"Thickness (gauge) of Paper, Cardboard, and Cardboard Combined with note 3 for stacked sheets The micrometer used to perform the T 11 om-89 test is an Emveco 200-A Tissue Calibrator Tester available from Emveco, Inc., of Newberg, Oregon. 2.00 kilo-pascals (132 grams per square inch) a foot pressure area of 2500 square millimeters, a pressure foot diameter of 56.42 millimeters, a dwell time of 3 seconds and a decrease rate of 0.8 millimeters per second The size of the products of this invention can be from about 10 to about 4000 microns, more specifically from about 100 to about 2000 microns, and even more specifically from about 100 to about 800 microns.

Optional chemical additives may also be added to the base sheet or product formed to impart additional benefits to the product and process considering that they are not antagonistic to the intended benefits of the invention. Examples of such additives include charge promoters, wet strength agents (permanent and temporary), dry strength agents, debonders and softening agents, all of which are well known in the art. Such chemicals can be added at any point in the process, including being added simultaneously with the chemicals that provide the temperature change.

Change promoters and control agents are commonly used in the papermaking process to control the zeta potential of the supply to make paper at the wet end of the process. These species may be anionic or cationic, more usually cationic, and may be either naturally occurring materials such as alum or synthetic polymers of high density of change and low molecular weight typically of molecular weight of less than 500,000. Drain and retention aids can also be added to the supply to improve training, drainage and fine retention. Included within the retention and drainage aids are micro-particle systems that contain a high surface area, highly anionic charge density materials.

Wet strength agents and dry strength agents can also be applied to the tissue, either directly or to the fibers within the tissue prior to tissue formation. As used herein, "wet strength agents" are materials used to immobilize the bonds between the fibers in the wet state. Typically, the means by which the fibers are held together in the paper and tissue products involve hydrogen bonds and sometimes combinations of hydrogen bonds and covalent and / or ionic bonds. In the present invention, it may be useful to provide a material that will allow the binding of fibers in such a way as to immobilize fiber-to-fiber bonding points and make them resistant to disruption in the wet state. In In this instance, the wet state will usually mean when the product is heavily saturated with water or other aqueous solutions, but it can also mean significant saturation with body fluids such as urine, blood, mucus, menstrual fluid, fluid intestinal movement, lymph and other exudates. of the body .

Any material which, when added to a fabric or sheet of paper, results in providing the sheet with a ratio of medium geometric wet tensile strength to the average dry geometric tensile strength in excess of 0.1 is, for purposes of this invention, a wet resistance agent. Typically, these materials are referred to as either "permanent" wet strength agents or as "temporary" wet strength agents. For purposes of differences between the permanent wet strength of the storm, the permanent will be defined as those resins that, when incorporated into paper or tissue products, will provide a product that retains more than 50 percent of its original wet strength after exposure to water for a period of at least five minutes. Temporary wet strength agents are those that show less than 50 percent of their original wet strength after being saturated with water for five minutes. The amount of wet strength agent added to the pulp fibers before tissue formation can be about 0.1 percent or dry weight or greater, more specifically around 0.2 percent by dry weight or greater, and even more specifically from about 0.1 to about 3 percent by dry weight, based on the dry weight of the fibers. Permanent wet strength agents will provide a more or less long term wet flexibility to the structure. In contrast, temporary wet strength agents can provide structures that have high flexibility and low density, but that can not provide a structure that has a long term resistance to exposure to water or body fluids.

Temporary wet strength additives can be cationic, non-ionic, or anionic. Commercially available composites include: PAREZ® 631 NC and PAREZ® 725, which are cationic glyoxylated polyacrylamides, available from Cytec Industries (of West Paterson, New Jersey); Hercobond 1366, which is also a cationic glyoxylated polyacrylamide manufactured by Hercules, Inc. (of Wilmington, Delaware); and dialdehyde starches, such as Cobond 1000® from the National Starch and Chemical Company.

Permanent wet strength agents comprising cationic or polymeric oligomeric resins useful for the purposes of this include epichlorohydrin-polyamine-polyamide type resins such as KYMENE 557H sold by Hercules, Inc. (of Wilmington, Delaware). Other cationic resins include polyethyleneimine resins and resins aminoplast obtained by the reaction of formaldehyde with melamine or ure. It is often advantageous to use permanent and / or temporary wet strength resins in the manufacture of tissue products such as facial tissue, bath tissue, and paper towels.

Dry strength resins can also be applied to the fabric to control the dry strength of the resulting product. Such materials are well known in the art and include, but are not limited to, modified starches and other polysaccharides such as cationic, amphoteric, and anionic starches and guar and locust bean gums, modified polyacrylamides, carboxymethyl cellulose, sugars, polyvinyl alcohol, chitosan , and similar. Such dry strength additives are typically added to the fiber slurry prior to the formation of the sheet or as part of the crepe pack.

Sometimes it may be advantageous to add additional binder or chemical smoothing agents to the sheet. Examples of debonders or softening chemistries are widely taught in the art. Exemplary compounds include the simple quaternary ammonium salts having the general formula (R1 ') 4_b-N + - (R1") bX ~, wherein R1' is a C6_6 alkyl group, R1" is a C14 alkyl group C22 b is an integer from 1 to 3 and X "is any suitable against ion." Other similar compounds include the onoster, diester, monoamide, and diamide derived from simple quaternary ammonium salts. A number of variations on these quaternary ammonium compounds are known and should be considered to fall within the scope of the present invention. Additional softening compositions include cationic oleyl imidazoline materials such as Prosoft TQ-1003, available from Hercules, Inc. Such softeners may also incorporate a humectant or a plasticizer such as a low molecular weight polyethylene glycol (molecular weight <4,000). Daltons) or a polyhydroxy compound such as glycerin or propylene glycol. These softeners can be applied to the fibers while in a slurry prior to the formation of the sheet to aid in volume softness.

When salts are incorporated at relatively high levels in the leaf, a certain level of value can be imparted to the leaf. To counteract this value, it may be beneficial to topically apply a polysiloxane to the sheet to improve the feeling of softness. The presence of the polysiloxane will have little impact on the change in temperature and, in general, any polysiloxane known in the art useful as a topical softening agent can be used to impart the desired softness to the product or base sheet. Particularly suitable polysiloxanes include aminofunctional polysiloxanes, polyether polysiloxanes, polyether amino functional polysiloxanes and mixtures thereof. When polysiloxanes with sheets of the present invention are used, if the Water is used as the external stimulant to cause the temperature change, the polysiloxane must be used on a level or in conjunction with wetting agents in such a way that the hydrophobicity of the product does not exceed certain limits. To this end, the Automatic Gravimetric Absorbency Test (AGAT) (defined below) can be used to measure the water intake in the products. The Automatic Gravimetric Absorbance Test (AGAT) values for the products of the present invention can suitably be about 0.4 g / g / s1 / 2 or greater, more specifically about 0.5 g / g / s1 / 2 or greater , and more specifically around 0.7 g / g / s1 / 2 or greater. When water is not used as the activator to induce the temperature change, no specific requirement is necessary for the water intake rates with respect to the function of the invention.

The "Automatic Gravimetric Absorbency Test (AGAT)" is a test that generally measures the initial absorbency of a tissue sheet that has been aged for 2 weeks at 130 degrees Fahrenheit. The apparatus and the test are well known in the art and are described in U.S. Patent No. 4,357,827 entitled Gravimetric Absorbency Tester and issued November 9, 1982 to McConnell, which is incorporated herein by reference. In general, the value of the Automatic Gravimetric Absorbentness Test (AGAT) is determined by testing a stack of six representative samples of a tissue product. During In the test, the sample cell is placed on the test cell that is in communication with the reservoir container. A valve is then opened in such a way that the liquid is free to flow from the container to the test cell. The tissue stack being tested absorbs liquid from the reservoir container. The amount of liquid taken by the battery is determined for a period of time. In particular, the Automatic Gravimetric Absorbency Test (AGAT) machine generates an absorption curve from 2.25 seconds to as much as desired. The result of the Automatic Gravimetric Absorbance Test (AGAT) is obtained by measuring the average inclination between 2.25 and 6.25 seconds. Ten replicas are run for each product and the average of the ten replicates is the value of the Automatic Gravimetric Absorbance Test (AGAT) for that product.

Other chemicals that may be added to the products of this invention include absorbency aids, usually in the form of cationic, anionic or non-ionic surfactants, humectants and plasticizers, such as low molecular weight polyethylene glycols, and polyhydroxy compounds, such as glycerin. and propylene glycol. Materials that provide skin health benefits, such as mineral oil, aloe extract, vitamin E, lotions in general and the like may also be incorporated into the tissue. Further materials include odor control agents, such as odor absorbers, fibers and particles of activated carbon, baby powder, baking soda, chelating agents, zeolites, perfumes, or other odor masking agents, cyclodextrin compounds, oxidants, and the like. Super absorbent particles, synthetic fibers, or films can also be used. Additional options include cationic dyes, optical brighteners, humectants, emollients, fillers such as kaolin clay, titanium dioxide, and the like.

In the interest of brevity and concreteness, any ranges of values indicated in this specification contemplate all values within the range and should be constructed as support for the claims by pointing out any sub-ranges that have endpoints that are values of integers within the specified range in question. By way of a hypothetical illustrative example, a description in this specification of a range from 1 to 5 should be considered in the support claims to be any of the following ranges: 1-5; 1-4; 1-3; 2-5; 2-4; 2-3; 3-5; 3-4; and 4-5.

Examples Approximately 5 grams of NaN02 was dissolved in 100 cubic centimeters of distilled water. A standard two-layer facial tissue was then soaked in the solution and the excess of water squeezed by hand. The tissue sheet was placed in an oven at 65 degrees Celsius and left to dry for 1 hour. The leaf was removed from the oven and left to cool.

In a similar way, about 5 grams of CaCl2 was dissolved in 100 cubic centimeters of distilled water. A standard two-layer facial tissue was then soaked in the solution and the excess of water squeezed by hand. The tissue sheet was placed in an oven at 65 degrees centigrade and left to dry for 1 hour. The leaf was removed from the oven and left to cool in a vacuum desiccator. After cooling the sheet was immediately cut to size and to the sample as follows.

Each of the above tissue sheets was cut into approximately 1-inch strips weighing 0.5 grams. The strip was then wrapped securely around the bulb of a thermometer and the recorded temperature. The transparent tape, such as the Scotch® brand transparent tape, can be used to secure the strip to the thermometer considering that sufficient exposed tissue is present to allow absorption of the water. The thermometer was then placed in a vial of 100 cubic centimeters and 1.0 of distilled water was then added to the tissue and the temperature change recorded.

(Note: when cooling solutions are used it is necessary to use a vial in such a way that evaporation of the water does not lead to erroneous results.) The temperature was observed to determine the maximum or minimum temperature that was reached. The results are listed in the table given below.

It will be appreciated that the foregoing description and examples are for purposes of illustration and are not to be construed as limiting the scope of the invention, which is defined by the following claims and all equivalents thereto.

Claims (17)

1. A product comprising a fibrous absorbent sheet containing one or more chemical agents that react exothermically or endothermically when the sheet is subjected to an externally applied non-thermal stimulus such that the temperature of the sheet increases or decreases by at least 1 ° C or more.

2. The product as claimed in clause 1 characterized in that one or more of the chemical agents are encapsulated and the non-thermal stimulus not applied externally is of sufficient pressure to break the capsules and release the encapsulated chemical agent or agents.

3. The product as claimed in clause 1 characterized in that one or more of the chemical agents are encapsulated in a water soluble encapsulant and the externally applied non-thermal stimulus is water absorbed inside the sheet to dissolve the capsules and release the chemical agent or agents encapsulated.

4. The product as claimed in clause 1 characterized in that the externally applied non-thermal stimulus is water absorbed within the sheet

5. The product as claimed in clause 1 characterized in that the reaction is exothermic.

6. The product as claimed in clause 1 characterized in that the reaction is endothermic.

7. The product as claimed in clause 1 characterized in that at least one of the chemical agents is a salt.

8. The product as claimed in clause 1 characterized in that the absolute value of enthalpy of the salt solution is about 2,000 calories per mole or more.

9. The product as claimed in clause 1 characterized in that the salt is selected from the group consisting of KCl, NH4N03, NaN03, NHC1, CaCl2, LiCl and NaC2H302.

10. The product as claimed in clause 1 characterized in that the fibers of the absorbent fibrous sheet essentially consist of cellulosic fibers.

11. The product as claimed in clause 1 characterized in that it is selected from the group consisting of facial tissue, bath tissue and paper towels.

12. The product as claimed in clause 1 characterized in that the temperature of the sheet increases or decreases by about 3 ° C or more.

13. The product as claimed in clause 1 characterized in that the temperature of the sheet increases or decreases around 5 ° C or more.

14. The product as claimed in clause 1 characterized in that the temperature of the sheet increases or decreases from 1 ° C to around 10 ° C.

15. The product as claimed in clause 1 characterized in that the temperature of the sheet increases or decreases from about 2 ° C to about 10 ° C.

16. The product as claimed in clause 1 characterized in that the temperature of the sheet increases or decreases from about 3 ° C to about 6 ° C.

17. The product as claimed in clause 1 characterized in that it comprises two outer layers and one or more inner layers wherein the sheet containing the chemical agents is an inner layer. E S U M E N Fibrous sheet materials, such as are useful as facial tissue, bath tissue and paper towel, for example are provided with chemical agents, such as certain salts, which create a leaf change when exposed to a particular stimulant. such as water, for example. These materials can provide a calming effect to the user either in the form of cooling or heating depending on the use of the particular chemical involved.