US 3916447 A
A protective covering is disclosed having at least one layer of synthetic polymeric microfibers bonded to at least one other layer of cellulosic fibers. The exposed microfibers exhibit a tendency to cling to other natural fibers found in clothing or other webs, while the exposed cellulosic fibers present an absorbent surface. The combination is a soft, flexible, aqeuous liquid-barrier web useful as a dinner napkin, bib, furniture cover, or the like.
Description (OCR text may contain errors)
I United States Patent 1191 Thompson LOW COST, ABSORBENT, CLINGING,
AQUEOUS LIQUID BARRIER PROTECTIVE COVERING  Inventor: Lenore E. Thompson, Menasha,
 Assignee: Kimberly-Clark Corporation,
 Filed: Apr. 24, 1972  Appl. No.: 247,116
 References Cited UNITED STATES PATENTS 2,768,247 10/1956 Graham 161/152 3,016,599 1/1962 Perry 161/169 3,097,991 7/1963 Miller et a1. 161/169 3,180,335 4/1965 Duncan et a1. 128/287 3,251,360 5/1965 Melges 128/132 D 3,310,459 3/1967 Guthrie 128/296 3,410,266 11/1968 Krzewinski 128/132 D 3,416,526 12/1968 Yeremian 128/296 3,484,330 12/1969 Sokolowski... 128/132 D 3,485,705 12/1969 Harmon 128/290 W Nov. 4, 1975 3,503,391 3/1970 Melges 128/132 D 3,509,009 4/1970 Hartmann 161/150 3,530,023 9/1970 Schutte et a1.. 161/152 3,532,800 10/1970 Wyly et a1 161/150 3,561,440 2/1971 Bayer et a1 128/132 D 3,595,235 7/1971 Jespersen 128/284 3,619,816 11/1971 Cowen 161/250 3,647,594 3/1972 Demme... 161/156 3,654,059 4/1972 Zisblatt 161/169 3,674,613 7/1972 Lavigne 161/250 3,695,985 10/1972 Brock et a1. 161/150 3,704,198 11/1972 Prentice 161/150 3,837,995 9/1974 Floden 161/150 FOREIGN PATENTS OR APPLICATIONS 1,217,892 l2/1970 United Kingdom OTHER PUBLICATIONS Wente, V. A., Industrial and Engineering Chemistry 48(8), 1342-1346 (1956).
Primary Examiner-George F. Lesmes Assistant Examiner-.1. Cannon Attorney, Agent, or FirmDaniel J. Hanlon, Jr.; William D. Herrick; Raymond J. Miller ABSTRACT A protective covering is disclosed having at least one layer of synthetic polymeric microfibers bonded to at least one other layer of cellulosic fibers. The exposed microfibers exhibit a tendency to cling to other natural fibers found in clothing or other webs, while the exposed cellulosic fibers present an absorbent surface. The combination is a soft, flexible, aqeuous liquidbarrier web useful as a dinner napkin, bib, furniture cover, or the like.
2 Claims, 6 Drawing figures US. Patent Nov. 4, 1975 Sheet 1 01*2 3,916,447
US. Patent Nov. 4, 1975 Sheet 2 of2 3,916,447
1 LOW COST, ABSORBENT, CLINGING, AQUEOUS LIQUID BARRIER PROTECTIVE COVERING BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to low-cost protective coverings having a bonded, multi-ply construction. More particularly, it concerns such coverings combining at least one layer of synthetic thermoplastic polymeric microfibers with at least one layer of cellulosic fibers. The combination exhibits desirable properties such as cling, strength, aqueous liquid-barrier capabilities and absorbency.
2. Prior Art Description The use of paper or other low-cost webs for the protection of objects from liquid contact has become very common. Fimiliar examples in the single-use disposables area include table napkins and bibs, as well as many others. More limited use protective coverings are also included such as, for example, headrest covers for airline passenger seats. These items are conventionally made of paper, usually creped wadding, or nonwoven materials. In most, if not all, such applications, it is desirable that the web remain in position on the user, seat, etc. until intended to be removed. Conventional paper webs have been unsuccessful to a large degree in meeting this objective even when positive fastening means have been employed. Efforts heretofore to economically render such webs clinging or self-attaching have met similarly with little success.
For many uses, including those mentioned, it is highly advantageous to have a web with good aqueous liquid barrier properties. Thus, coffee or milk, for example, spilled on a bib or napkin will not readily transfer to the garment underneath. Conventional napkins and tissues have substantially failed to provide this protection. Attempts to increase the barrier properties of such webs have been made, for example, by laminating them with a film layer. These attempts, while successful in that regard, have significantly increased the cost of such products and detrimentally affected a number of other properties, such as drape and cling.
Formed webs of synthetic thermoplastic polymeric microfibers are known. For example, work done at the Naval Research Laboratories in Washington, DC. is described by Van A. Wendt in an article entitled Superfine Thermoplastic Fibers appearing in INDUS- TRIAL AND ENGINEERING CHEMISTRY, Vol. 48, No. 8, pgs. 1342 to 1346. It is also known to combine these microfibrous webs with other layers or components to form filter material or the like. Furthermore, it is known to form synthetic electrical papers from such microfibrous webs. Examples of such products may be found by reference to British Pat. No. 1,217,892 and U.S. Pat. No. 3,532,800.
SUMMARY OF THE INVENTION Briefly, in accordance with the invention, there is provided an absorbent, strong, flexible, aqueous liquidbarrier protective covering including at least one layer of synthetic polymeric thermoplastic microfibers bonded to at least one layer of cellulosic fibers. The microfiber and cellulosic fiber layers may be adequately bonded autogenously simply by contact as described, for example, in copending U.S. application Ser. No. 247,130 filed Apr. 24, 1972 by John G. Floden, now Pat. No. 3,837,995, entitled Autogenously Bonded Composite Web and assigned to the assignee of this 2 application; alternatively, known laminating processes may be utilized. Preferably the polymeric microfibers have diameters of 10 microns or less, and the cellulosic fibers are of a larger size, usually 20 to 40 microns in diameter.
The resulting composite web is soft and strong with a tendency exhibited by its microfibrous surface to adhere tenaciously to most common fabric materials, especially those containing natural fibers.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates schematically an embodiment of the invention showing the two layer structure in roll form, where one layer is composed of the microfibers and the other layer is composed of cellulosic fibers;
FIG. 2 illustrates the protective covering of the invention in the form of a bib;
FIG. 3 illustrates the protective covering of the invention in the form of a table napkin;
FIG. 4 illustrates the protective covering of the invention in use as a furniture cover;
FIG. 5 illustrates the protective covering of the invention in the form of a disposable handkerchief; and
FIG. 6 illustrates in partial view a special purpose tissue and dispenser.
DESCRIPTION OF THE PREFERRED EMBODIMENTS As used herein the term microfiber layer may be defined as a non-woven web of generally discontinuous fibers predominantly having a diameter in the range less than about 10 microns.
The term synthetic thermoplastic polymer is intended to include all man-made polymers capable of melt extrusion into microfibers. This embraces, in particular, polyolefins, polyamides, and polyesters. The preferred thermoplastic polymers include polyolefins, especially polypropylene. The web weight of the microfibrous layer is not critical and, in general, may vary within the range of 0.5 to 30 grams per square meter depending upon the particular properties desired in the composite structure. Increased web weights result in higher overall strength and opacity. For most uses, the web weight range of from 5 to 20 grams per square meter is preferred. While the particular length of these microfibers is not critical, they are usually discontinuous when formed. A method for forming such fibers is not a part of this invention, and the one described, for example, in the article by Wendt, supra, as well as in Naval Research Laboratory Report 1 1 1,437 dated Apr. 15, 1954 entitled Manufacture of Superfine Organic Fibers can be utilized. Generally, the process involves the extrusion of molten polymeric material into fine streams and attenuating them by opposing flows of high velocity heated gas, usually air. As formed the microfibrous web displays some two-sidedness with the surface contacting the collector (usually a belt) being more free from loose and extended fibers. It is preferred that, when bonding to the other layer, the microfibrous web be positioned so that the belt side (surface contacting the collector) will be exposed in the resulting composite. This generally results in stronger interlayer bonding due to the greater degree of fiber entanglement.
For enhanced aqueous liquid barrier properties, the use of hydrophobic polymers is preferred, and diameter ranges of 2 to 6 microns are also considered most desirable. While the web thus remains vapor permeable and is not uncomfortable to skin contact, it still acts as a barrier to the passage of aqueous liquids. The term liquid barrier for the purpose of this invention means having a Mason Jar test rating in excess of 30 minutes. The Mason Jar test is conventionally used and described as follows: 600 milliliters of water is placed in a 1 quart Mason jar; a piece of the material to be tested is placed on the top of the jar and fastened in place with an O ring; the jar is inverted and placed on a flat glass plate with the fluid head being about 4 inches. The time required to wet the plate is a measure of the water repellency of the material.
The term autogenously bonded is used to describe the tendency of the microfibrous and cellulosic fiber layers to adhere to each other when brought into contact. The bonds thus formed need not be supplemented by adhesive or physical means and generally exceed about 0.40 g/cm as measured with an Instron Universal Test Instrument using the A cell attachment and set for maximum sensitivity.
For cellulosic layers, the use of tissue or creped wadding in the basis weight range of from about 10 to about 60 grams per square meter is preferred. However, other cellulosic fibrous materials, such as air laid felts, may be utilized as well. For most disposable and limited use applications, though, tissue and creped wadding provide the advantages of ready availability and low cost.
The layer of cellulosic fibers may be dry or wet formed and have a thickness generally from 0.5 to 50 and preferably from 1 to 5 times the thickness of the microfibrous layer. The size of the cellulosic fibers is not critical so long as they have an average diameter substantially larger than the average diameter of the microfibers. For example, cellulose fibers having an average diameter in the range of from about to about 50 microns have been used, and the range of from to 40 microns is preferred. The cellulosic layer may include one or more separate plies, and when a plurality of plies are used, they may be supplementally bonded to each other as by the use of adhesives or physical bonding means such as needling or embossing.
EXAMPLES The following examples illustrate the invention in terms of a number of preferred combinations of microfibers and cellulosic fibers and related embodiments.
EXAMPLE 1 A multipurpose sheet material in roll form was prepared by combining conventional cellulosic tissue (Kleenex single ply facial grade tissue) and microfiber webs. The tissue had a basis weight of about 15.77 grams per square meter, and the microfiber web was made up of polypropylene fibers having an average fiber diameter predominantly in the range of from about 2 microns to about 6 microns and basis weight of about 15.42 grams per square meter. The webs were united by placing the microfiber web in position with the side having the greatest number of loose fibers against the tissue web and running the two plies over an idler roll. The resulting composite was perforated at 16 inch intervals, trimmed, and wound onto cores in I00 sheet lengths convenient for consumer use.
FIG. 1 illustrates this embodiment in somewhat schematic form showing roll 10 of sheets 12 wound on core 14. The sheets are two ply with the thermoplastic microfibers 16 on one surface and the larger, cellulosic fibers 18 on the opposite side. Perforation line 20 provides for easy separation of the individual sheets 12.
4 These sheets can be simply dispensed and placed wherever a protective covering is desired, or used for other similar purposes.
' EXAMPLE 2 An infant bib was prepared from a combination of tissue and microfibrous polypropylene formed in the manner of Example 1. The composite sheets were cut by hand into sections of 14 inches by 17 /2 inches with a cut-away section at the neck.
FIG. 2 illustrates the bib 22 schematically showing microfibers 16 and cellulosic fibers 18 on opposing surfaces. Yoke 24 is formed by ends 26 resulting from the cutout. The bib may be simply pressed into position and will resist displacement during normal use.
EXAMPLE 3 A table napkin was formed from the composite web of Example 1 by processing the material with a conventional (Paper Converting Machine Company) napkin folder machine which folded, cut and stacked the product from 15 inch by 15 inch sheets into eighths.
FIG. 3 schematically illustrates the dinner napkin 28 showing plies of microfibers 16 and cellulose fibers 18 combined and folded along lines 30 and transversely along fold 32. Other folding methods, of course, may be utilized to provide napkins of desired configurations. When unfolded and pressed gently into position on ones lap, the napkin will resist displacement from most clothing during normal use.
EXAMPLE 4 A protective furniture cover in the form of a headrest cover was prepared from the composite of Example 1. The sheet was cut to 14 inch by 17 /2 inch covers and interfolded into stacks for convenient distribution.
FIG. 4 schematically illustrates this embodiment in use. Seat 34 includes base 36, armrests 38, seat cushion 40 and back 42 including headrest portion 44. The protective covering 46 is pressed into position on headrest 44 with the microfibers l6 contacting the fabric of the seat, and the absorbent cellulosic fibers l8 exposed. Once in position, it will resist displacement during normal use. Of course, similar furniture protective coverings may be utilized where desired, for example, on armrests 38.
EXAMPLE 5 A disposable handkerchief was prepared utilizing two tissue layers similar to those used in the previous examples and a center ply of polypropylene microfibers as in Example 1 and having a basis weight of about 7.42 grams per square meter. The microfiber web was combined with the first tissue layer as in Example 1, then a second tissue ply was joined, and the composite run over a second idler roll. Sheets of 16 inches by 16 inches were cut and folded into sixteenths by hand to form strong, absorbent handkerchiefs.
FIG. 5 schematically illustrates this embodiment showing handkerchief 48 of three-ply construction with exposed cellulosic fibers l8 and center ply of thermoplastic microfibers l6.
EXAMPLE 6 A superstrength facial tissue was prepared from the composite of Example 5 by cutting it into 10 inches by l0 inches sheets which were interfolded by hand and placed in top dispensing cartons.
FIG. 6 illustrates this embodiment showing facial tissues 50 including exposed cellulose fibers 18 and center ply of microfibers 16. As shown the tissues 50 are interfolded along lines 52 for dispensing through open- 6 Thus, it is apparent that there has been provided in accordance with the' inventiori, an improved, strong, low cost, absorbent, clinging, aqueous liquid barrier web that fully satisfies the objects, aims and advantages ing 54 in carton 56. These tissues are extra strong when 5 set forth above. While the invention has been described compared with conventional facial tissues and are espein conjunction with specific embodiments thereof, it is clally suited for heavy duty applications. evident that many alternatives, modifications and vari- In order to demonstrate the highly advantageous tenations will be apparent to those skilled in the art in light dency of the webs produced ln accordance with the of the foregoing description. Accordingly, it is intended present lnventlon, to cling or self-attach to various 10 to embrace all such alternatives, modifications and varfabrlcs, the following test was devisedi a inch by 15 iations that fall within the spirit and broad scope of the inch sheet prepared as in Example 3 was smoothed appended claims. onto a fabric by hand in the manner that one might I claim: spread a napkin onto his lap. This was done with seven 1. In combination, a fabric garment containing natudlfferent fabrics with the microfiber layer contacting 15 ral fibers and a protective cover attached to said fabric the fabrlc. The composites were hung vertically from a garment, llne, suspended by the fabrics only, and the time the improvement wherein said protective cover is of elapsed before they dropped was measured. A conveninterbonded, multi-layer construction having as a tlonal paper Kleenex dinner napkin was included as a first surface in contact with said garment, a layer control. substantially composed of generally discontinuous, Table I describes the results of these tests: thermoplastic, hydrophobic microfibers having an Table I average fiber diameter of from about 2 microns to about 6 microns and a basis weight in the range of Protective Fabric Type Covering Time Elapsed from 0.5 to grams per square meter and, as an exposed second surface, a layer havln-g a basis i883: g ss 3 2 weight of from about 10 to 60 grams per square [00% Rayon 5 meter substantially composed of absorbent cellu- 100% Flax 5 losic fibers, 100% Jute 5 h b 100% Acrylic 5 sa1 protective cover avlng aqueous lqLlI arrler 65% Polyester, Cotton 5 30 propertles and a tendency to cllng to sald fabric 100% Cotton Conventional dinner napkin Less than arment d resist di lacement d i normal I second g p g 100% Rayon use. 2. In combination, an article of furniture having a Test terminated after 5 hours fabric outer material containing natural fibers and a protective cover attached to said fabric, Table II Basis Handleometert 2) Tensile( 3) Energy( 3) Sample NO. Plies Weight Bulk(l) MD CD MD CD MD CD g/m inches in grams/3" g. g.
Example 3 2 31.2 0.0099 7.4 5.4 2048 1323 2836 3240 Kleenex 2 3L5 0.0105 l5.2 95 I824 528 795 I60 Dinner Napkin Kleenex 2 35.0 0.0220 9.9 8.9 l9l8 639 990 265 Boutique Napkin (I )As measured on the Ames Bulk Tester Model No. l3
(3)Tensile and energy measurements made with The lnstron Universal Test Instrument F.S. 10,000 grams Example 1 setting CT 20"lmin. CM 20"min. Jaw span 4" Kleenex Dinner Napkin F.S. 5,000 Kleenex Boutique Napkin PIS. 5,000 I The barrier properties of webs produced in accorthe improvement wherein said protective cover is of dance with this invention are also superior to cellulosic webs and comparable to film laminates with a Mason Jar test rating in excess of 30 minutes. The properties of drapability, strength and softness are shown by Table II to be improved, in general, in the composites of this invention. Since no supplemental bonding is required between the layers of microfibers and cellulosic fibers the desirable properties of each layer may be retained or enhanced. When appropriate, however, these composite webs may be treated as by means of wet strength resins, adhesives, or other finishes, for example, to develop specific properties in the same manner as used for conventional disposable or limited use materials.
interbonded, multi-layer construction having as a first surface in contact with said fabric, a layer substantially composed of generally discontinuous, thermoplastic, hydrophobic microfibers having an average fiber diameter of from about 2 microns to about 6 microns and a basis weight in the range of from 0.5 to 30 grams per square meter and, as an exposed second surface, a layer having a basis weight of from about 10 to 60 grams per square meter substantially composed of absorbent cellulosic fibers,
said protective cover having aqueous liquid barrier properties and a tendency to cling to said fabric and resist displacement during normal use.