US3520016A - Absorbent wipes - Google Patents

Description

July l14, 1970 G. H. MEiTNER 3,520,016

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United States Patent O1 hee 3,520,016 Patented July 14, 1970 3,520,016 ABSORBENT WIPES Gary H. Meitner, Oshkosh, Wis., assignor to Kimberly- Clark Corporation, Neenah, Wis., a corporation of Delaware Filed Oct. 9, 1968, Ser. No. 766,195 Int. Cl. A471 25/08 U.S. Cl. -209 5 Claims ABSTRACT OF THE DISCLOSURE A wipe embodying a at, low-density, absorbent pad composed of a multiplicity of layers of creped cellulosic tissue, which absorbs and holds large amounts'of organic cleaning solvent, or water, and releases such liquids readily under wiping pressure, and a gauze envelope wrapped around the pad which protects the pad from tearing, screens loose pad fibers from escaping, and provides a rough, non-abrading surface for better cleaning.

DESCRIPTION OF THE INVENTION This invention relates to improvements in highly absorbent wipes for applying cleaning solvent.

Heretofore in cleaning metal surfaces, for example, in cleaning grease, oil and dirt from the metal skin of aircraft before painting, it has been common practice to apply cleaning solvents to the surface with fabric such as gauze folded into pads. When such pads become choked with dirt they either must be cleaned, requiring storage which raises a problem of tire hazard, or disposed of. Even gauze, however, is a somewhat expensive material for a disposable pad.

The principal object of this invention is to provide an inexpensive, disposable, wipe for cleaning operations that involve the use of either organic solvents or water.

A related object is to provide such a wipe that will meet stringent limitations as to the amounts of constituent materials which will be extracted from the wipe by the organic solvents or water with which the wipe is to be used.

Another object is to provide a wipe that incorporates a pad of light, low-density, multi-ply creped tissue product to obtain high capacity to absorb and hold organic solvents or water, and a gauze cover material to improve the structural integrity of the pad particularly at its edges, to screen pad bers from escape to the surface being cleaned, and to enhance the appearance of the wipe.

Another related object is to provide such a wipe which will leave the surface being cleaned substantially clear of fibers and will be usable on surfaces having slight projections, such as caused by rivets or by uneven edges at joints or seams between metal plate, which tend to catch the face of the wipe and pull the fibers of the material therefrom.

Another object is to provide such a wipe which can be manufactured at lower cost and may, therefore, be treated as a disposable product to eliminate the safety hazard involved in storage of solvent saturated pads.

Further objects will be apparent from the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a top plan view of a wipe constructed of a multi-ply pad wrapped in a gauze envelope;

FIG. 2 is a sectional view taken along line 2 2 of FIG. l;

FIG. 3 is a greatly enlarged fragmentary sectional view as indicated in FIG. l;

FIGS. 4 and 5 are fragmentary plan views illustrating alternative methods of fastening side edges of the gauze envelope.

Referring now more particularly to the accompanying drawings, the invention is embodied in a wipe represented in FIG. l, comprising a multi-ply pad 10 and a gauze fabric envelope 12 wrapped around the pad 10 and having sewn side edges 13 and unfastened ends 14 which project beyond the edges of the pad. It has been found that a wipe so constructed and utilizing a multi-ply creped tissue product for the pad 10 which has a lowdensity within a preferred range provides a high capacity to absorb organic solvents or water, which are used for cleaning surfaces such as the metal skin of aircraft prelminary to painting, and will readily release such liquids for their cleaning action upon the application of hand wiping pressure.

In accordance with the invention, the product for the pad 10 is comprised of a multiplicity of layers 15 of creped cellulosic tissue united by uniformly distributed embossments 16. To provide a pad 10 having superior solvent absorbency and release characteristics, the layers of creped cellulosic tissue preferably have a low density within a range of between about 0.02 gram/cm.3 and 0.06 gram/cm3. Such a product for the pad has been made by employing nine plies of coarsely creped tissue 17 (crepe ratio about 1.8) having a dry, uncreped basis weight of between 4.5 and 6 pounds per ream of 3000 square feet and asembling the nine plies of coarsely creped tissue 17 with cover sheets 18 of finely creped tissue (crepe ratio of about 2.70) having a dry, uncreped basis weight of about 4.5 pounds per ream of 3000 square feet, so as to produce a composite product with a density of about 0.026 gram/cm.3 (1.62 pounds/f). Multiple layers of coarsely creped tissue sheets having a basis weight within the range of from about 4.5 to 6 pounds per 3000 square feet and a crepe ratio within the range of 1.6 to 2.2 pounds also are suitable for the pad product without also employing such finely creped tissue cover sheets 18, although there is a small sacrifice in appearance when such a product is used for the pad because of the less uniform surface texture of the coarsely creped tissue 17. Of course, when multiple layers of coarsely creped tissue comprise the product used for the pad, such product should preferably be made so that it has a density within the range specified.

To illustrate the superior solvent absorbency and releasibility characteristics of wipes constructed in accordance with the invention and having a pad made from multiply tissue product having a density within the preferred range, it has been found that rectangular 8" x 9" wipes approximately 1A" thick and so constructed, hold up to 68% more methyl ethyl ketone solvent and up to 154% more water than all gauze wipes of the same weight.

By comparing the solvent capacity of wipes having different density multi-ply tissue pads, it has been discovered that the solvent capacity per wipe increases as the density of the pad product decreases. For example, measurements of methyl ethyl ketone solvent capacity show that a multiply creped tissue product with a density of 0.099 gram/ cm.3 (and thus substantially above the preferred range) will hold 6.0 grams solvent per gram of product, while a multi-ply tissue product with a density of 0.026 gram/ cm.3 (within the preferred range) will hold 9.0 grams solvent per gram of product. This comparison demonstrates a 50% greater solvent capacity for the low density preferred pad material, and wipes constructed therewith hence provide substantially higher solvent capacity per wipe.

In addition to having higher solvent capacity per wipe, wipes constructed according to this invention also release solvent better under hand wiping pressure than all gauze pads and hence are effective to carry more solvent to the surface being cleaned. Wipes so constructed also are more effective in delivering solvent under hand wiping pressure than wipes constructed with pads of higher density (i.e.,

0.099 gram/cm?) multi-ply creped tissue product because the amount of solvent which may be squeezed from each wipe is about 50% of its solvent capacity; since the solvent capacity of the Wipe of this invention is greater, the amount of solvent delivered to the surface being cleaned will be greater per wipe.

It has been found that wipes constructed according to the invention not only are more effective for carrying solvent to the surface being cleaned, due to the highly absorbent character of the pad and the open non-blocking cover afforded by the gauze envelope, they are also more effective for carrying dirt and other foreign matter away from the surface being cleaned. After the lfresh solvent has been squeezed by hand from the wipe to flood the surface being cleaned, dirt, grease and other foreign matter freed from the surface and floating or dissolved in the solvent is absorbed into the pad and thereby removed.

Further in keeping with one of the main objectives of the invention, namely, to provide a wipe which after the solvent has dried will leave the cleaned surface Substantially free of residue extracted by the solvent from the wipe, the elements of the Wipe are made lfrom materials characterized by substantial absence of constituents extractable in organic solvents including methyl ethyl ketone and certain other organic solvents listed below, or water. To accomplish this end, the multi-ply product for the pad has been made from kraft or sulte pulps, or mixtures thereof, with or Without wet strength resins added, which meet the requirements of low extractables in the specified solvents.

The following tabulations present test results obtained by the Soxhlet method of testing for extractables in the solvents listed from the designated pulps, which test results demonstratethat creped tissue made from such pulps will meet the low extractables requirement, for example, of less than 0.5%.

SOFTWOOD KRAFT PULP Solvent: Percent extractables Acetone 0.21 Methyl ethyl ketone 0.17 Toluene 0.18 Carbon tetrachloride 0.13 Water 0.25

SOFTWOOD SULFITE PULP Solvent: Percent extractables Acetone 0.41 Methyl ethyl ketone 0.39 Toluene 0.29 Carbon tetrachloride 0.30 Water 0.28

SOFTWOOD KRAFT PULP WITH 0.75% KYMENE 557 WET STRENGTH RESIN Solvent: Percent extractables Acetone 0.40 Methyl ethyl ketone 0.18 Toluene 0.15 Carbon tetrachloride 0.14 Water 0.30

Further in keeping with the aim to provide a wipe which will leave substantially no residue of extractables from the Wipe materials, the gauze envelope 12 is preferably woven of cotton threads without binders, and its side edges rather than being adhesively bonded are preferably stitched or embossed for integrity of the composite assembly. The side edges 20 (FIG. 2) are sewn with stitches through the pad to enhance structural integrity, or said side edges 20' are embossed (FIG. 4), so that no adhesives or binders which might be leached out by organic solvents such as listed in the above tabulations, are employed. Stitching provides an envelope and composite assembly which holds together better than embossed edge pads and, therefore, sewn edges are preferred. In the gauze envelope for the preferred form of wipe the ends are unsewn, with the margins of the gauze envelope projecting substantially beyond the pad, so that the raw edges of the material of the pad are protected and fibers from the pad are screened from escaping through the gauze. It has been found that the gauze cover and its projecting margins protect the pad from the tearing action of projections on the surface being cleaned, such as rivets on metal surfaces which tend to tear the fibers of the pad free, and provides a rough, open non-abrading surface to aid in cleaning.

The gauze cover also prevents the tissue of the pad from pilling, which is a rolling up of bers when the surface of the tissue is abraded by rubbing. The open mesh of the gauze (illustratively 9 x 14) allows the dirt and grime to pass through the gauze cover and be absorbed into and retained by the pad 10 until the mesh becomes choked or the pad laden with dirt. Wipes so constructed have been found particularly useful for cleaning aircraft surfaces before painting, wlere grease or oil, dust, and varnish-like or lacquer-like screen materials which are soluble in the cleaning solvents, are on the surfaces and must be removed. By virtue of their high capacity for carrying solvents, and their high absorbency for removing the cleaning liquids, wipes made in accordance with this invention are more elfective for such cleaning operation than prior products such as all gauze pads. They also retain the advantageous rough surface characteristics of folded cheese cloth or gauze, While providing a softer feel and a product into which the dirt penetrates more readily and is then trapped than pads of such cheesecloth or gauze.

Several gauze plies may be used on either one or both faces of the pad where a stronger or rougher cover is desired. The threads of the gauze plies do not align to any substantial extent over the face of the wipe and the multiplicity of threads appear to provide the increased roughness characteristic. Moreover, instead of a woven cover fabric for the envelope, in keeping with the invention a non-woven gauze fabric with binder resistant to specified solvents may be used for the envelope where the Wipe is intended solely for cleaning operations involving such specified solvents. Also, as shown in FIG. 5, the cover fabric may be fastened at its side edges by a strip 22 of adhesive where the wipe is intended solely for cleaning operations with particular solvents that do not attack the material of the strip. For example, the gauze may be fastened by a polyvinyl alcohol adhesive, providing a wipe which meets low extractables requirements (preferably below 0.5%) for all solvents listed in the above tabulations except water. As another example, the gauze may be attached with strips of polyethylene to provide a wipe which meets such low extractables requirements in water, acetone and methyl ethyl ketone.

As illustrated in FIG. l, the plies of coarsely creped tissue 17 and finely creped cover sheets 18 are united by embossments 16 which cover 2 to 10% of the area of the pad and, together with the sewn or embossed edges, insure the structural integrity of the composite assembly of pad and gauze envelope. As illustrated in FIG. 3, said embossments deeply penetrate both faces of the pad, and for cleaning operations where large size dirt or foreign matter particles might be present on the surface being cleaned, the embossments also may provide retention cavities for such particles. For uses where suicient pad integrity is obtained by sewing or adhesively joining the pad edges, the tissue plies may be assembled wthout the addition of embossments to further unite the layers of tissue.

I claim as my invention:

1. An absorbent wipe including a flat, low-density, multi-ply pad comprised of a multiplicity of layers of creped cellulosic tissue, wrapped in a gauze envelope, said envelope having gauze sheets covering the opposite faces of the pad and fastened together along at least one edge of the pad,.the gauze sheets being unfastened along the remaining edges of the pad with margins of said sheets along said unfastened edges projecting substantially beyond the pad thereby protecting said pad over its surfaces and along its edges from the tearing action of uneven surfaces over Which the wipe is rubbed, said pad having a density of between about 0.02 and 0.06 gram/cm3.

2. A wipe according to claim 1 in which said pad is rectangular and said envelope is formed by only a single gauze sheet on at least one of the opposite faces of said pad, said sheets being sewn together along two edges of said pad and being unfastened along the remaining two edges of said pad.

3. A Wipe according to claim 1 in which said envelope is formed by a gauze sheet on each of the opposite faces of said pad, said sheets being fastened together along at least one edge of said pad by adhesive.

4. A wipe according to any one of the preceding claims in which said envelope and said layers of creped cellulosic tissue contain less than 0.5% solids which are extractable in solvents of the group consisting of acetone, methyl ethyl ketone, toluene, and carbon tetrachloride.

5. A Wipe according to any one of preceding claims 1, 3 or 4 in which the gauze of said envelope is a woven cotton fabric, in which the fastening of said envelope is by sewing along at least one of said side edges, and in which said envelope and said layers of creped cellulosic tissue contain less than 0.5% solids which are extractable in solvents of the group consisting of acetone, methyl ethyl ketone, toluene, carbon tetrachloride and water, so as to provide a Wipe having less than 0.5% extractables in said solvents.

References Cited UNITED STATES PATENTS 1,786,513 l2/193() Zuckerman 15--208 X 2,233,746 3/1941 Potter 15-209 2,297,639 9/ 1942 Thauwald 15-209 X 2,902,395 9/1959 Hirschy et al 15--209 X 2,932,839 4/1960 Flanigan et al. 15-209 X 3,124,825 3/1964 Iovenko 15-l04.93 3,396,420 8/1968 Mitchell 15-210 FOREIGN PATENTS 360,066 l1/l93l Great Britain.

WALTER A. SCHEEL, Primary Examiner L. G. MACHLIN, Assistant Examiner U.S. Cl. X.R.

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