Treatment of fabrics in machine dryers

Abstract

Fabrics are treated in machine drying apparatus to reduce static electricity carried by the fabrics, soften the fabrics and improve other fabric properties. A sponge impregnated with a heat softenable solid or semi-solid fabric-conditioning agent is placed within the dryer drum and the fabrics are tumbled in the dryer thereby causing some of the fabric-conditioning agent to be transferred to the fabric. When the dryer is heated, the heat of the dryer helps the fabric-conditioning agent to soften and assists in its distribution over the surface of fabric with which the impregnated sponge is brought into tumbling contact.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application describes an impregnated sponge which can be used in the method and apparatus of copending patent application Ser. No. 232,432 filed Mar. 7, 1972.

BACKGROUND OF THE INVENTION

In laundering it is common to treat various types of fabrics such as wool, cotton, silk, nylon, polyester, permanent-press, and the like with chemicals which are fabric-conditioning or treating agents to render the fabrics soft to the touch, to reduce tangling, knotting or wrinkling, to render them free of static electricity, to render them bacteria-resistant, to deodorize them, and to otherwise condition them. For example, the proper use of fabric conditioners permits dried clothes to be sorted and folded more easily and quickly. These results are ordinarily achieved by introducing an aqueous solution or dispersion of the fabric-conditioning agent into the wash water during the washing cycle of the laundry process or by introducing such an aqueous solution or dispersion of fabric-conditioning agent into the rinse water during the rinsing cycle of the laundry process. Experience has shown that addition of the fabric-conditioning agents during the rinse cycle of the laundry process is often significantly more effective than addition of the fabric-conditioning agents during the wash cycle. Since some clothes washing machines do not have automatic fabric softener dispensers, a homemaker must be present during the washing of fabrics to manually add the fabric conditioner during the rinse cycle. This is an extra step, inconvenient and, consequently, is often forgotten. Even when the washing machine is equipped with an automatic dispenser, the use of a fabric-conditioner is still a messy operation requiring measuring of a liquid suspension, is wasteful and is ecologically undesirable because a significant amount of the fabric conditioner is lost to the drain. Moreover, the fabric softener is usually added to the deep rinse where some soap or detergent and soil may still be present, leading to redeposition problems and interaction between the anionic detergent and cationic softeners (which are mutually incompatible), with subsequent loss of efficiency.

As a result of combinations of the above factors, a survey has shown that many homemakers use fabric softeners irregularly and on the basis of "when I remember" or "when it is needed." This results in irregular performance as evidenced by static electricity and other fabric properties (e.g., softness).

The use of liquid fabric conditioning agents in machine dryers has been suggested in the past, but the idea has not gained widespread commercial acceptance probably as a result of such factors as the need for complex dispensing equipment.

Recently, it was suggested in U.S. Pat. No. 3,442,692 that chemicals which are fabric-conditioning agents might be applied to fabrics by tumbling or co-mingling the fabrics in a laundry dryer in contact with a fibrous substrate such as paper or cloth which has been coated with a chemical which is a fabric-conditioning agent. The chemical agent is presumably transferred to the fabrics to be conditioned by the tumbling action of the fabric within the dryer.

SUMMARY OF THE INVENTION

The present invention is based on the discovery that desired fabric properties (e.g., anti-static properties) can be obtained by treating the fabric in a machine dryer with a very small amount of a fabric-conditioning agent such as an anti-static agent, which agent is present in a multi-use reusable form. Briefly, described, the method of the present invention involves locating within the dryer a sponge which has been impregnated with a heat softenable material comprising a fabric conditioning agent such as an anti-static agent. Optionally, this impregnated sponge can be contained within a dispenser, a portion of which is permeable so that the fabric-conditioner can be released through the dispenser when the fabric conditioner is softened by the heat of the dryer. For example, a small rectangular sponge (e.g.,5 cm .times. 10 cm .times. 1 cm) can be impregnated with such a fabric conditioning agent and then encased within a cloth envelope. This cloth envelope can be removably mounted on a leading edge of one of the dryer vanes, which vanes form a part of the dryer drum wall. The fabric conditioning agent will have a softening or melting point within the range of the dryer temperature. When the fabric to be treated is tumbled within the heated dryer drum, the anti-static agent will pass through the cloth envelope and transfer to the fabric.

THE DRAWINGS

FIG. 1 is a front view of a machine dryer.

FIG. 2 is a cross-sectional view of a sponge which has been impregnated with a heat softenable fabric conditioning agent.

FIG. 3 is a perspective view of an impregnated sponge encased within a cloth dispenser.

DETAILED DESCRIPTION

Method of Treating Fabrics

The present method of treating fabrics in machine dryers can be understood by referring to the following description when read in conjunction with the drawings.

In FIG. 1 is shown a machine dryer generally designated by the Numeral 1. The dryer 1 includes a heat source (not shown) which may be electric, gas, or other. The dryer is provided with a rotating drum 2 and an exhaust 3. Dryer 1 is further provided with an access door 4 and a latch 5.

Rotating drum 2 of dryer 1 is typically provided with a plurality of vanes 6 which extend inwardly from the cylindrical wall of drum 2 and which are generally parallel to the axis of rotation of drum 2. Although drum 2 might rotate in either direction, it has arbitrarily been shown in FIG. 1 to rotate in a clockwise direction. An impregnated sponge 7 is carried by one of the vanes 6. The purpose of impregnated sponge 7 is to distribute a fabric-conditioning agent onto fabric 8 being tumbled within drum 2. As shown in FIG. 1, the impregnated sponge 7 is secured to a leading edge of one of the vanes 6. However, if desired, several impregnated sponges 7 can be attached to a single vane 6 or several impregnated sponges 7 can be attached to different vanes 6. Although an impregnated sponge 7 can be loosely tumbled with the clothes or other fabric 8 (i.e., it does not need to be attached to the drum), attaching the impregnated sponge 7 to the drum 2 avoids the disadvantage of having to sort the impregnated sponge 7 from the clothes 8 after each dryer load. Moreover, various placements of the impregnated sponge 7 in drum 2 can be used to alter dispensing rates or compensate for different dryer types, makes, temperatures, drying cylces, and the like.

In operation, fabric 8 (usually damp and ready to be dried) is placed within drum 2 and the fabric 8 (e.g., clothes) is tumbled within the drum 2 by rotation of the drum 2. In this manner, the fabric 8 is brought into repeated contact with a surface of impregnated sponge 7. The heat from the dryer causes the fabric-conditioning agent to soften and be transferred to the fabric 8 by contact between the tumbling fabric 8 and the surface of impregnated sponge 7.

It has been observed that some beneficial anti-static properties can be obtained by merely tumbling dry clothes in an unheated dryer. Presumably, fabric-conditioner which is on or near the outer surface of the impregnated sponge 7 is transferred to the fabric through abrading contact with the fabric.

The Impregnated Sponge

The details of construction of the impregnated sponge 7 of FIG. 1 are shown in more detail in FIG. 2. Although sponge 7 is hereinafter described with reference to means for attaching it to a dryer drum 2, it will be appreciated that the fastening means could be omitted and the impregnated sponge 7 simply tumbled loosely within drum 2. However, best results are obtained if the impregnated sponge 7 is attached to some portion of the dryer drum 2, preferably a vane 6.

Impregnated sponge 7 can be prepared by melting one or more fabric conditioning agents (e.g., a normally solid quaternary ammonium chloride), optionally in admixture with various additives, carriers or the like, and pouring or otherwise contacting a sponge with the molten mixture. Usually, the amount of molten material will be about 0.3 to 0.7 grams per cubic centimeter of un-impregnated sponge, although more or less molten material may be used. Impregnation of the sponge can be assisted by kneading or otherwise manipulating the sponge to cause the molten fabric conditioning agent to penetrate further into the interior of the sponge. The sponge used in the practice of the present invention may be of natural or synthetic origin (e.g., a polyurethane foam). Desirably, the pore size of the sponge will be relatively fine, usually averaging between about 0.05-4 millimeters (e.g., 0.1 to 2 mm) in diameter as measured in the plane of a cut surface of the sponge.

After a sponge has been saturated or otherwise impregnated with molten fabric conditioning agent, the impregnated sponge 7 will be allowed to cool to room temperature. It will then become relatively firm or rigid. When properly impregnated, the cell structure of the sponge surface may still be seen (i.e., the cells are not over-filled with fabric conditioning agent).

As previously indicated, it is desirable for the impregnated sponge 7 to be pre-positioned within the drum 2 of dryer 1. Although a variety of means may be used to fasten the impregnated sponge 7 to the dryer, the arrangement shown in FIG. 2 is particularly effective. As shown in FIG. 2, an impregnated sponge pad 7 is backed with cloth or heavy paper 9. To this assembly is attached (by sewing or adhesives) the hook half 10 of a hook and loop fastener (e.g., Velcro). The loop half 11 of the hook and loop fastener is attached to an adhesive strip 12, one surface of which is protected with glazed backing paper 13.

When it is desired to install the impregnated sponge 7 in a clothes dryer 1, the glazed backing paper 13 can be removed from adhesive strip 12 and the adhesive strip firmly secured by pressing it against the leading edge of a dryer vane 6. The impregnated sponge pad 7 can then be selectively attached or removed at will by merely pressing the hook half 10 of the hook and loop fastener into the loop half 11 of the hook and loop fastener, or by pulling the hook and loop halves of the fasteners apart.

For some purposes, it may be desirable to reduce the rate of transfer of fabric conditioning agent from impregnated sponge 7 to the clothes 8, particularly during the early cycles in which the impregnated sponge 7 is used. Improved control over the dispensing rate of the fabric conditioning agent can be obtained by covering the impregnated sponge 7 with a permeable material. As shown in FIG. 3, this can be accomplished by encasing the impregnated sponge pad 7 within a cloth envelope 14. The side of the envelope not shown can be provided with fastening means (such as shown in FIG. 2) for attaching the envelope-covered, impregnated sponge 7 to a portion of the dryer drum 2.

Fabric-Conditioning Agents

The fabric-conditioning agents useful in the practice of the present invention are those chemicals used for fabric-conditioning, particularly anti-static agents, which either soften when heated to the operating temperature of a laundry dryer or which can be made to soften at such temperatures by proper compounding with other chemicals. Liquid fabric-conditioning agents are not practical for use in the present invention unless they can be formed into a suitable gel or other heat softenable solid. Thus, the use of solid and semi-solid fabric-conditioning agents (particularly those which impart anti-static properties) is preferred over the use of liquid agents which are formed into a heat softenable mass.

A particularly useful class of fabric-conditioning agents comprises the quaternary ammonium salts. Desirably, such quaternary salts will be the chlorides and will contain at least one and usually two C.sub.12 -C.sub.24 fatty acid radicals (e.g., C.sub.18 radicals). One preferred product is dimethyl di (hydrogenated tallow) ammonium chloride, whether used alone or in a mixture with other chemicals. If desired, two or more fabric-conditioning agents can be blended together. Additives can be used to improve bar-forming characteristics, modify the softening point of the bar and to control the rate of migration or penetration of the agents from the contact surface of impregnated sponge 7 or through the permeable portion of a dispenser in which the sponge is located.

A particular useful mixture of fabric-conditioning agents is a mixture of stearyl dimethyl benzyl ammonium chloride and dimethyl di (hydrogenated tallow) ammonium chloride in a weight ratio of 2-4:1.

In formulating any bar containing a fabric conditioner, the bar should have a melting or softening point within the operating temperature range of the dryer. It is helpful if the bar has a softening point that is broad (i.e., it melts or softens over a wide range of temperatures) as contrasted to a sharply defined or narrow melting point. For many machine dryers, bars having a softening point range of at least 10 C. .degree., and preferably at least 20 C. .degree. are preferred. At the present time, the optimum softening point of the bar appears to be within the range of 50.degree.-90.degree.C.

The present invention is further illustrated by the following specific example. Unless otherwise indicated, all parts and percentages are by weight.

EXAMPLE I

A 3/8 inch thick polyurethane sponge, of relatively fine porosity (0.3 to 1 mm cell size), backed with a heavy glazed paper was cut into rectangular pieces 13/8 by 23/4 inch. Next, the hook half of a Velcro fastener 3/4 by 2 inch was sewn onto the paper backed side of each sponge pad, with the hooks facing away from the paper back.

A powdered blend consisting of 25 percent dimethyl di (hydrogenated tallow) ammonium chloride, 72 percent stearyl dimethyl benzyl ammonium chloride and 3 percent coconut monoethanol amide was carefully heated (to avoid discoloration) to 160.degree.-180.degree.C in a beaker and poured over the sponges. At 160.degree.C, it was found necessary to squeeze or knead the sponges with a glass rod to work the molten fabric conditioner into the sponge interior. At 180.degree.C, the molten fabric conditioner readily penetrated the sponges with very little squeezing action. Approximately 15-20 grams of the molten mixture was impregnated into each sponge, the exact weight being determined by weighing the sponges before and after impregnating. Before impregnation, the sponges with fastener, each weighed about 2.2 grams. The impregnated sponges were allowed to cool to room temperature. whereupon they hardened or set up as a firm bar. After impregnation and cooling, the cell structure at the sponge surfaces could still be seen.

To complete the assembly of each sponge, the mating loop half of the Velcro fastener was positioned over the hook half (now attached to the impregnated sponge) and the two halves were pressed together. Next a piece of double faced adhesive tape 3/4 by 2 by 1/16 inch was placed over the back side of the loop half of the Velcro fastener and pressed to form a bond, leaving the glazed protective paper of the urethane adhesive tape in place to protect the virgin side of the tape. For test purposes the impregnated sponges were attached to a suitable interior clothes dryer surface by first thoroughly cleaning the immediate area of the attachment. Next the glazed protective paper was removed from the urethane adhesive tape and the impregnated sponge was positioned and pressed onto the desired location. To assure firmer adhesion of the loop side of the Velcro fastener, the impregnated sponge was carefully detached and the adhering loop side (which remained attached to the clothes dryer surface) was firmly pressed into place by rubbing briskly with the fingers. The impregnated sponge was reattached to the drum by carefully aligning the mating halves of the Velcro fastener and pressing firmly.

Two of the impregnated sponges were evaluated by running a 20 cycle wash and dry test using a normal 7-8 pound load of clothes with dryer settings of: (a) 120.degree.F; and (b) 160.degree.F. respectively. The actual exit air temperature was recorded at both settings with a recording thermometer and found to be about 130.degree. and 150.degree.F., respectively, for these two settings. The use of fabric softener for each cycle was determined by detaching and weighing the impregnated sponge pad after each dry cycle and reattaching it for the next cycle.

The weight loss during the early cycles was somewhat higher than for the later cycles during the 20 cycle runs. The rate of weight loss may be controlled by varying the porosity, varying the sponge cell strength, impregnating the sponge with less fabric conditioner, altering the softening range of the fabric conditioner, covering the impregnated sponge with a thin, fine, poromeric or permeable membrane, by using a sponge with poregradient such that the base will have relatively large pores and the contact surface will have relatively fine pores, or by other means.

The 20 cycle wash and dry tests summarized in Table I (120.degree.F Dryer Setting) and in Table II (160.degree.F Dryer Setting) demonstrate the advantages of the present invention. "Marking" refers to the possible tendency of the fabric softener to be transferred to portions of the fabric in such large amount as to leave readily detectable, visable marks on the fabric.

TABLE I __________________________________________________________________________ WEIGHT LOSS AND PERFORMANCE OF SPONGE IMPREGNATED ANTISTAT OF EXAMPLE I DRYER SETTING 120.degree.F __________________________________________________________________________ Number of Wash & Dry Weight of Weight Cycles Impregnated loss/cycle Observation for Static, Completed Sponge gms Cling, Marking, etc. __________________________________________________________________________ 0 14.3g -- -- 5 11.6 0.5g No static or clinging, tangling, knotting, no marking for all cycles 10 10.9 0.14 No static or clinging, tangling, knotting, no marking for all cycles 15 10.5 0.10 No static or clinging, tangling, knotting, no marking for all cycles 20 10.1 0.10 No static or clinging, tangling, knotting no marking for all cycles Average weight loss/cycle for 20 cycles: 0.2 gm. __________________________________________________________________________

TABLE II __________________________________________________________________________ WEIGHT LOSS AND PERFORMANCE OF SPONGE IMPREGNATED ANTISTAT OF EXAMPLE I DRYER SETTING 160.degree.F __________________________________________________________________________ Number of Wash & Dry Weight of Weight Cycles Impregnated loss/cycle Observation for Static, Completed Sponge gms Cling, Marking, etc. __________________________________________________________________________ 0 19.7 -- -- 5 15.0 0.9 No static or clinging, tangling, knotting, no marking for all cycles 10 13.3 0.3 No static or clinging, tangling, knotting, no marking for all cycles 15 12.2 0.2 No static or clinging, tangling, knotting no marking for all cycles 20 11.2 0.2 No static or clinging, tangling, knotting no marking for all cycle Average weight loss/cycle for 20 cycles: 0.42 gm. __________________________________________________________________________

Claims

What is claimed is:

1. An article of manufacture comprising:

a. an impregnated sponge having an average pore size of 0.05 to 4 millimeters which has been impregnated from its surface into its interior with about 0.3 to about 0.7 gram, per cubic centimeter of unimpregnated sponge, of a heatsoftenable fabric conditioning agent comprising a quaternary ammonium salt, said fabric conditioning agent having a softening point range of at least 10 C. .degree. being softened within the range of 50.degree. to 90.degree.C.; and

b. attaching means operably associated with said impregnated sponge for attaching the impregnated sponge to a wall of a machine dryer.

2. The product of claim 1 in which the sponge has an average pore size of from 0.1 to 2 mm.

3. The product of claim 2, wherein said attaching means includes a woven loop and hook fastener.

4. The product of claim 3 wherein the impregnated sponge is contained within a cloth envelope, and said attaching means is attached to said cloth envelope.

5. The product of claim 3 wherein the fabric conditioning agent comprises dimethyl di (hydrogenated tallow) ammonium chloride.

6. The product of claim 1 wherein the sponge has a smaller pore size along one surface of the sponge relative to the pore size along the opposite surface of the sponge.

7. The product of claim 1 wherein the impregnated sponge is contained within a dispenser, at least a portion of which is permeable to the fabric conditioning agent under the conditions of use.

8. An article of manufacture comprising:

a. an impregnated sponge having an average pore size of from 0.1 to 2 mm which has been impregnated from its surface to its interior with about 0.3 to about 0.7 gram, per cubic centimeter of unimpregnated sponge, of a heat-softenable, solid or semi-solid fabric conditioning agent consisting essentially of stearyl dimethyl benzyl ammonium chloride admixed with dimethyl di (hydrogenated tallow) ammonium chloride in a weight ratio of about 2:1 to about 4:1, said fabric conditioning agent having a softening point range of at least 10 C. .degree. and being softened within the range of 50.degree. to 90.degree.C; and

b. attaching means operably associated with said impregnated sponge for attaching the impregnated sponge to a wall of a machine dryer, said attaching means including a woven loop and hook fastener.