US 2980941 A
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Description (OCR text may contain errors)
April 1961 R. E. MILLER 2,980,941
CLEANINGSHEET Filed Dec. 8, 1958 CAPSULES CONTAINING LIQUID CLEANER FIG. 2 CAPSULES CONTAINING LIQUID CLEANER Qi/FuLLERs EARTH PARTICLES 3 CAPSULES CONTAINING LIQUID CLEANER INVENTOR ROBERT E. MILLER HIS ATTORNEYS .CLEANING SHEET Robert E. Miller, Dayton, Ohio, assignor to The National Cash Register Company, Dayton, Ohio, a corporation of Maryland I Filed Dec. s, 1958, Ser. No. 778,643 8 Claims. c1. 15506) This invention relates to a cleaning sheet including a base web of absorbent fabric, and the base web fabric in cluding, in or on it, solid particles of an adsorbent material such as fullers earths, interspersed with or in juxtaposition to minute pressure-rupturable capsules each containing a liquid soil remover, said liquid preferably being of an evaporable nature, but not necessarily so. The capsules are ruptured when the cleaning sheet is rubbed against an article to be cleaned, freeing the liquid soil remover, which, together with the adsorbent nature of the particles of solid material and the absorbent nature of the fabric base web renders the cleaning sheet exceptionally efiicient for its purpose, as the removed soil is thereby retained on or in the sheet either by the base web fabric or the adsorbent particles.
The fact that the liquid soil remover is contained in capsules keeps the paper in a dry state, as far as superficial contact is concerned, until used, and such containment prevents the evaporation of the liquid soil remover if such is of a volatile nature. The liquid soil remover used in the capsules is such as to enable it to remove oily marks of a surface of a material to be cleaned. The com-' bination of an absorbent base web fabric, adsorbent particulate material, and a liquid soil remover, is known and is disclosed in United States Letters Patent 995,904, which issued on the application of John R. Rentz, June 20, 1911, but in that disclosure the soil removing liquid was not encapsulated and, consequently, was free to evaporate and rendered the sheet damp to the touch. In the present invention, the cleaning sheet feels dry and can be stored indefinitely without deterioration, by evaporation, of the liquid material.
It is within the scope of the invention to have particulate adsorbent solids of different kinds mixed together in the paper, and, likewise, it is within the scope of the invention to have a mixture of capsules containing different soil-removing liquids, or to have a mixture of soil-removing liquids in the same capsules.
The invention will be described with reference to the drawing, of which:
Fig. 1 is a diagrammatic cross-sectional view of the form of the invention in which the adsorbent material is in a coating next to the web (of paper) which is overlaid with a coating of the liquid-containing capsules;
Fig. 2 is a diagrammatic cross-sectional view of the for-tn of the invention in which the adsorbent material and the capsules are intermixed and applied as a coating to the web (of paper);
Fig. 3 shows the fibrous web (of paper) impregnated with' the adsorbent material, the web being overlaid with a coating of the capsules.
The absorbent base web preferably is made of untreated paper fibers, as shown in Figs. 1 and 2, although the solid adsorbent particulate materials may be mixed With the pulp before the paper sheet is formed, and thus become entangled in the paper fibers of the sheet, as shown'in Fig. 3. An incorporation of adsorbent material in the pulp fibers themselves before they are made into a paper sheet, is the subject matter of an application for I United States Letters Patent, Serial No. 552,237, filed by Leon Paquin, on November 29, 1955, which issued into United States Patent No. 2,902,399 on September 1, 1959, wherein an alumina-silicate material, of an adsorbent nature, is formed in the pulp suspension before the paper is made from the pulp fibers. Another way of incorporating the particulate adsorbent material in paper is simply to stir it in the pulp fiber suspension before it is made into a paper sheet. The preferred method, however, is to coat the solid adsorbent particles on a sheet of paper,
' either with the liquid-containing capsules interspersed therein, as shown in Fig. 2, or coated over such particu-- late absorbent coating after it is applied to the sheet and dried, as shown in Fig. 1.
Among the solid particulate materials which may be used are the well-known fullers earths, such as montmorillonite, kaolin, bentonite, natural or artificial sodium aluminum silicate zeolite materials, and artificially activated forms of the aforementioned materials. There are a large number of such adsorbent materials which may be used, but, for the purposes of the preferred embodiment of this invention, attapulgite is chosen as being very suitable for such purposes as it is very efiicient and is readily obtained from natural deposits.
In the United States Patents 2,581,186, which issued on the application of Barrett K. Green, on January 1, 1952, and 2,641,557, which also issued on the application of Barrett K. Green on January 9, 1953, there are disclosed papers which are coated with zeolite material and with attapulgite material, respectively, and which, if they had applied thereto a coating of pressure-rupturable capsules containing a soil-removing liquid, would serve the purposes of this invention.
, The principal object of this invention is to provide a cleaning sheet of an absorbent base web fabric, so coated with adsorbent particulate material and with capsules containing soil-removing liquid, that, by rubbing it on the surface of an object to be cleaned, it is activated by rupture of the capsules and release of the liquid soil remover, to loosen and remove soil, particularly of an oily nature,
which removed soil is adsorbed and absorbed by the cleaning sheet. It will be understood, therefore, that the cleaning sheet has the three characteristics of solvent action, adsorbent characteristics, and absorbent characteristics, which operating in a concerted relation prove most effective for the purposes stated.
There are several methods known for incorporating the soil-removing liquid within the pressure-rupturable capsules, one of them being disclosed in United States Letters Patent 2,800,457, which issued on the application of Barrett K. Green and Lowell Schleicher on July 23, 1957, and another being disclosed in United States Letters Patent 2,800,458, which issued on the application of Barrett K. Green on July 23, 1957.
In the preferred embodiment of the invention, it is proposed to make the liquid-containing pressure-rupturable capsules of a diameter of under 10 microns, by .a process similar to that disclosed in the Green and Schleicher United States Patent No. 2,800,457, wherein a large amount of liquid is contained in only the least necessary encapsulating wall material that will keep the liquid from being dissipated during ordinary handling and storage conditions, before being required for use.
In the preferred embodiment, grams of diethyl-,
7, and the temperature being kept at about 55 degrees centigrade, throughout the process, until the capsules are finally formed. To" thissolution-minture is added 60 milliliters" of a 1%, by weight, aqueous solution of polyvinylrnethylethermaleic anhydride copolymer, havingj'a pH of 9, andthe'n' adjusting the whole of theflinixture solutionto pH 9. Finally, thereis' added850 grams of water and, after thorough incorporation of theing're'die'nts, the pH is lowered to 416, by the addition" of a 10%", by weight, aqueous solntion'of acetic acid, drop by drop, with continuous stirring, which stirring is continued as the temperature then is dropped to ,14 degrees centigrade, which solidifies the walls on the formed capsules, after which there is stirred in 10 milliliters of a 25% by weight, aqueoussolution of glutaraldehyde. The capsules which now contain the liquid soil remover are now corn plete, and the water content in which they are suspended may be adjusted to provide a coating slurry of the proper viscosity, and they maybe applied to paper which has in or on it the absorbent particulate material.
A second method of making the capsules involves the use. of carbon tetrachloride, which is added, drop by drop, in the amount of 150 milliliters into a mixture consisting of 180 grams of a 11%, by weight, aqueous gum -arabie solution, 180 grams of a 11%, by weight, aqueous gelatin solution, 40 milliliters of a 2%, by weight, aqueous solution of polyethylenemaleic anhydride copolymer at pH 9, and 1200 milliliters of water, the whole thereafter being adjusted to pH 7, the temperature being 7 maintained at '35 degrees centigrade. The materials are continuously stirred in a manner to reduce thedrop size of the carbon tetrachloride to between 50 and 400 microns, after which the pH is lowered to 5 to form an;initial capsular wall around each droplet. The pH then is raised to 5.5, using a 20%, by weight, aqueous solution of sodium hydroxide, and thereafter 40 milliliters of a 2%, by weight, aqueous solution of polyethylenemaleic anhydride copolymer is added with a slight rise to pH 6 noted. Immediately thereafter, the pH is adjusted to 5.3 and, with continued stirring, the temperature is allowed to fall to degrees centigrade. By this time, a second and thicker wall of the capsular material has formed around the initial wall of each partially formed capsule. Thereafter, l5 ccs. of 25%, by weight, aqueous solution of glutaraldehyde is added, and the stirring is continued for several hours to harden the then-finished capsules. The suspension of the so-rormed capsules may have the water adjusted to give the proper coating conditions desired to give the necessary thickness of the coating on the base web fabric, which coating should be a few thousandths of an inch in thickness.
The above two encapsulating techniques may be used to encapsulate other soil-removing liquids such as petroleum distillate (including fractions such as gasoline, kerosene, and light lubricating oil), toluene, xylene and other liinown water-soluble preferably volatile soil-removing uids.
A paper coating composition, including as the adsorbent particulate material, attapulgite, is set forth in the above-mentioned United States Letters Patent 2,641,557, of Barrett K. Green, in which 20%, by weight, of paper coating starch is cooked in water at 200 degrees Fahrenheit for fifteen minutes and allowed to cool to room temperature, followed by the dispersion therein of four parts, by weight, of a dispersion of 1 part, by weight, finely divided attapulgite, in three parts, by weight, of
water, to one part, by weight, of the starch solution.
The resultant mixture is applied to the selected paper at room temperature and dried, the coating preferably being of a thickness, more or less, of .001 to .005 of an inch. Other binders than the starch may be used, such being well known in theclarcuating-of-paper art, ex amples being casein, polyvinyl alcohol, animal glue, and obvious equivalents. The making of paper, including as the'adsorbent particulate material, zeolite, is described in the-beforementioned patent relating to zeolite-coated paper. The invention is not to be deemed limited in scope by the. particular soil-removing materials and coating compositions described, as the invention resides in the combination of the absorbent "base web fabric, the adsorbent-solid particulate matter, thereon or therein, and pressure-rupturable minute capsules containing soil-removing liquid positioned thereon or therein in juxtaposition. I
It will' be understood from the foregoing that the cleaning sheet, while containing'a considerable amount of available liquid soil-removing material, feels dry to the touch, and will remain in that condition until activated by being rubbed on a surface of material to be cleaned.
What is claimed is: y i
1. As an article of manufacture, a'cleaning sheet, in cluding an absorbent fabric web provided with a profusion of minute pressure-rupturable capsules, each cap- 'sule containing aliquid soil remover, and further provided with particles of adsorbent material for adsorbing the liquid and soil removed thereby, the cleaning sheet by being rubbed against the surface of an article to be cleaned, resulting in the rupture of the capsules, thus releasing the liquid to remove the soil'from the object to be cleaned, the liquid and included soil being adsorbed on the adsorbent particles and absorbed by the fabric web. 1
2. The cleaning sheet of claim'l in which theparticulate material and capsules are applied to the web as separate coatings in contact. I
- 3. The cleaning sheet of claim 1 in which the particulate material and capsules are interspersed and applied to the web as a coating.
4. The cleaning sheet of claim 1 in which the web is paper.
5. The cleaning sheet of claim 1 in which the particulate material is an adsorbent of water-insoluble liquids, and in which the liquid is water insoluble.
6. The cleaning sheet of claim 1 in which the web is paper and the particulate material and capsules are applied thereto as separate coatings in contact.
7. The cleaning sheet of claim 1 in which the web is paper and the particulate material and capsules are in' terspersed and applied to the sheet as a coating.
8. The cleaning sheet of claim 1 in which the web is paper, in which the particulate material is interspersed in the fabric thereof, and in which the capsules are applied to the paper as a coating.
References Cited in the file of this patent UNITED STATES PATENTS 995,904 Rentz June 20, 1911 1,056,067 Sporer Mar. 18, 1913 1,143,614 Criswell June 22, 1915 2,641,557 Green June 9, 1953 2,730,457 Green et al. June 30, 1953