United States Patent [19]
Chapman et al.
[ii] 4,075,382 [45] Feb. 21, 1978
[54] DISPOSABLE NONWOVEN SURGICAL TOWEL AND METHOD OF MAKING IT
[75] Inventors: Benjamin E. Chapman, Memphis,
Tenn.; Danny R. Moore, Perry, Fla.;
Arthur F. Phillips, Memphis, Tenn.
[73] Assignee: The Procter & Gamble Company,
Cincinnati, Ohio
[21] Appl. No.: 690,514
[22] Filed: May 27, 1976
[51] Int. C1.2 B32B 3/02; B32B 7/14;
B32B 27/10
[52] U.S. CI 428/192; 128/156;
128/296; 156/219; 156/290; 428/198; 428/507;
428/511; 428/515; 428/517
[58] Field of Search 428/192, 193, 194, 198,
428/195, 332, 507, 508, 509, 517, 515, 516, 519, 511; 128/156, 296; 156/88, 219, 220, 290
[56] References Cited
U.S. PATENT DOCUMENTS
3,053,252 9/1962 Wolf 128/296
3,434,472 3/1969 Herniman et al 128/296
3,654,060 4/1972 Goldman 128/156 X
3,881,210 5/1975 Drach et al 128/296 X
3,886,942 6/1975 Bernardin 128/296 X
3,888,248 6/1975 Moore et al 128/296 X
3,916,447 11/1975 Thompson 128/296 X
3,967,623 6/1976 Butterworth et al 128/156 X
3,971,381 7/1976 Gibson 128/296
Primary Examiner—-Thomas J. Herbert, Jr.
Assistant Examiner—R. Eugene Varndell, Jr.
Attorney, Agent, or Firm—Melville, Strasser, Foster &
Hoffman
[57] ABSTRACT
A nonwoven disposable towel, having particular utility as a surgical towel, comprising a five-ply structure and method of making it. The outermost plies of the towel are tissue. To each of these tissue plies there is adhered an intermediate ply constituting a medium density, thermoplastic, long fibered, nonwoven material. These tissue-intermediate ply assemblies comprise primary laminates accounting for four plies of the towel. Between these primary laminates there is located a fifth or center ply constituting a low density, melt blown, long fibered, nonwoven material. The entire structure is heat sealed about its periphery and additional spot heat bonds may be employed to minimize slippage between the center ply and the two primary laminates. The two primary laminates may be embossed prior to assembly of the towel.
26 Claims, 3 Drawing Figures
1
DISPOSABLE NONWOVEN SURGICAL TOWEL
AND METHOD OF MAKING IT
BACKGROUND OF THE INVENTION 5
1. Field of the Invention
The invention relates to a disposable towel and its method of manufacture, and more particularly to such a towel having particular utility as a surgical towel and comprising a unique five-ply structure including three 10 thermoplastic, long fibered, nonwoven plies and two outermost tissue plies.
2. Description of the Prior Art
While the nonwoven, disposable towels of the present invention may have many uses, they are particularly 15 suited for use as surgical towels and will be described in terms of that application.
In preparation for surgery, the surgeon (as well as the scrub nurse and other members of the operating team) will exercise much care in scrubbing his hands and arms 20 prior to entering the operating theatre. Then, after entering the operating theatre with his hands and arms still wet from the scrub, the surgeon must exercise as much care in the drying of his hands as in the scrubbing operation itself to prevent any contamination of his now 25 clean, but obviously not sterile, hands. While procedures vary from hospital-to-hospital and from doctorto-doctor, in general a towel is very carefully manipulated by a surgeon after scrubbing so as to dry his hands without introducing any contamination. Usually, one 30 side of the towel is reserved for the drying of each hand and separate portions of the towel are used for each wiping action. This avoids contamination from hand-tohand. In view of these procedures it is desirable that the towel being used demonstrates a minimum of moisture 35 strike through.
While composite nonwoven surgical towels have been substituted for the more common woven surgical towels, they have not met with universal acceptance. This is true not so much because they fail to perform 40 adequately from the standpoint of absorbency, drying ability and the like, but largely because they lacked the bulk, softness, drape, surface feel and cloth-likeness of the traditional woven surgical towel. Additionally, such composite nonwoven surgical towels generally demon- 45 strated too much strike through. Where steps were taken to prevent such strike through, the remaining characteristics listed above were even more lacking.
The present invention is directed to a nonwoven disposable towel having high absorptive capacity and 50 excellent drying ability with a minimum of strike through. Typically, a surgeon may have from about 15 to about 20 grams of water remaining on his hands and arms after the scrubbing operation. If he is a large man, he may have as much as 30 grams of water remaining. 55 The towel of the present invention has an absorptive capacity of about 4 to about 7 grams of water per gram of towel and weighs about 30 grams. Therefore, the towel of the present invention has a capacity of at least about 4 to 7 times the maximum amount of water to be 60 absorbed from the surgeon's hands and arms.
The towel of the present invention is substantially low in lint tendency, demonstrating excellent abrasion resistance, strength and sturdiness. At the same time, the towel is characterized by markedly improved ap- 65 pearance and surface feel. The towel is soft, cloth-like and is further characterized by desirable bulk, good conformability and drape. Drape, for example, is
2
needed to prevent contamination of the towel. If the towel is too stiff it will have a tendency to rub against the surgeon's scrub suit. This is also true if the towel, to provide sufficient absorptive capacity, must be made too long, too wide or both. Finally, the towel of the present invention may be easily and inexpensively manufactured and readily sterilized.
While particularly adapted for use as surgical towels, the nonwoven, disposable towel structures of the present invention may have many applications. For example, they may be used as professional towels or as hand towels or bath towels for hospital patients and the like. They may serve as disposable towels for use in hotels and motels or for use in institutions such as nursing homes, metal institutions, prisons and the like.
SUMMARY OF THE INVENTION
The nonwoven disposable towel of the present invention is made up of five plies. The outermost or surface plies are tissue plies. Various types of tissue may be used, as will be described hereinafter. Each tissue ply had adhered to its inner or unexposed surface an intermediate ply of a medium density, thermoplastic, long fibered, nonwoven material. The two tissue-intermediate ply assemblies comprise what will be termed hereinafter; "primary laminates". Between the two primary laminates there is located a fifth or center ply of low density, melt-blown, long fibered, nonwoven material. The medium density intermediate plies and the low density center ply are preferably formed of melt-blown polypropylene. Since this material is hydrophobic in nature, the center and intermediate plies of polypropylene are treated with a wetting agent to increase absorbancy.
The primary laminates are preferably subjected to hot or cold embossing and/or mechanical micro-compaction. This improves the surface texture, softness and appearance of the towel structure. When the primary laminates include outer plies of cellulose tissue, they are sprayed or coated on their tissue side with a material commonly used as wet resin to increase the wet abrasion resistance of the end product to withstand the hand and arm drying action of a surgeon, for example. The wet strength resin also ties down any loose cellulosic fibers.
When the primary laminates are located to either side of the center ply, the edges of the towel structure are heat sealed, thereby joining the primary laminates to the center ply. To prevent shifting of the center ply with respect to the primary laminates during a drying and wiping action, additional spot heat bonds may be made throughout the length and width of the towel structure, totally randomly or in a patterned arrangement which may additionally enhance the appearance of the towel.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of the towel of the present invention.
FIG. 2 is a perspective view of the towel of FIG. 1 and illustrating the individual plies thereof, the thickness of the plies being greatly exaggerated for purposes of clarity.
FIG. 3 is a fragmentary view diagramatically illustrating the cross section of the towel structure.
DESCRIPTION OF THE PREFERRED
EMBODIMENTS
Turning to the Figures wherein like parts have been given like index numerals, the towel of the present in- 5 vention is generally indicated at 1. As is clear from FIG. 2, the towel is made up of five plies. In FIG. 2 the five plies have been exaggerated in thickness for purposes of clarity.
The outermost plies 2 and 3 are made of tissue. Tissue 10 plies 2 and 3 are followed by intermediate plies 4 and 5 formed from medium density, thermoplastic, long fibered, nonwoven webs. Finally, the fifth or center ply 6, located between intermediate plies 4 an 5, is formed from a low density, melt-blown, long fibered, nonwo- 15 ven web.
Each of the five plies 2 though 6 must have certain characteristics. The outermost tissue plies 2 and 3 must be characterized by fast strike through, abrasion resistance, low linting tendencies, softness, flexibility, drape 20 and wet strength. In addition, these plies should present a good visual appearance inclusive of surface characteristics, texture and color, if a color is used. Finally, the outermost plies should be characterized by an excellent tactile impression, again inclusive of surface character- 25 istics, texture and the like.
The intermediate plies 4 and 5 should have a medium density. While other nonwoven material may be used, the intermediate plies 4 and 5 are preferably made up of thermoplastic fibers heat sealable to the center ply 6. 30 Plies 4 and 5 must also be capable of adhesive bonding to outermost tissue plies 2 and 3. The intermediate plies should be soft, flexible and possessed of adequate drape. They should also permit fast strike through and be inherently wetable or capable of being rendered wetable. 35
In addition to the characteristics listed for the tissue and intermediate plies, the primary laminates made therefrom should be embossable. Preferably, they should be heat embossable and heat setable. As a consequence of the characteristics of the tissue and intermedi- 40 ate plies making up each primary laminate, each primary laminate will display an adequate ability to absorb the stretch and energy of a wiping action. They will have good visual appearance and tactile impression. Above and beyond the necessary wet strength, the 45 primary laminates will be low in linting tendencies and high in abrasion resistance. The primary laminates will permit fast strike through of moisture to the center ply.
The center ply serves as the reservoir for the mositure absorbed by the towel structure and should be 50 inherently wettable or capable of being rendered wettable. It therefore should have high absorptive capacity and a wicking rate greater than that of the primary laminates. The center ply should be bulky and of low density, soft, bendable and capable of adequate drape. 55 The combination of absorptive capacity, wicking rate and bulk of the center ply 6 enables the towel structure to demonstrate a minimum of strike through from one outside surface to the other outside surface. While center ply 6 may be made of any appropriate nonwoven 60 material it is preferably made up of melt-blown, nonwoven, long fibered material, heat bondable to the adjacent primary laminates.
Outermost plies 2 and 3 may be made of any appropriate tissue having a basis weight of from 10 to 30 65 g/m2. The tissue may be made from wet-strength paper, carded webs, air-laid bonded fibrous webs, spun bonded webs, wet laid cellulose webs containing some long
cellulose or synthetic fibers, melt-blown polymer webs or the like. While not intended to be so limited, the plies 2 and 3 may be made of a wet strength cellulose tissue of the type taught in U.S. Pat. No. 3,301,746, in the name of Sanford, et al, dated Jan 31, 1967. Preferably a conventional cellulose tissue made on conventional tissue machines is used.
As indicated above, intermediate plies 4 and 5 are preferably made of thermoplastic fibers. They may be produced from spun bonded webs, for example. Preferably, they are derived from a medium density, meltblown, long fibered, nonwoven web. Such melt-blown webs are taught, for example, in the article entitled SUPERFINE THERMOPLASTIC FIBERS by Van A. Wente appearing in INDUSTRIAL AND ENGINEERING CHEMISTRY, Aug. 1956, Volume 48, No. 8 (pp. 1342-1346). While the melt-blown material may be nylon, polyester, or the like, a melt-blown polypropylene web is preferred.
Where a melt-blown polypropylene web is used for intermediate plies 4 and 5, the composition should be primarily linear polypropylene and the bonding should be medium. The web preferably has a basis weight of from about 10 to about 30 g/m2 and preferably about 15 g/m2. The web filaments should have a diameter of from about 1 to about 8 microns and preferably less than 4 microns. The web should be characterized by a tensile strength of from about 0.5 to about 1.5 lbs./in.; a minimum Elmendorf tear strength of at least about 20 g. in the machine and cross machine directions; a minimum elongation at maximum force of at least about 25% in the machine direction and at least about 35% in the cross direction; and a low load density of from about 0.06 to about 0.09 g/cc.
The low load density is determined in the following manner. The material to be tested is conditioned in a room maintained at 23 ± 1° C (73.4 ± 2° F) and 50 ± 2% relative humidity for a minimum of twelve hours prior to testing. The material to be tested must have an area large enough to provide a sufficient number of thickness measurements to accurately represent the material. Normally, five different locations will be sufficient to determine the average thickness of a nonwoven fabric material. The thickness is measured with a motorized, dead weight micrometer (having a total load of 300 g.) which lowers the micrometer anvil at a uniform rate and pressure on the surface of the material. Five determinations are made on each sample. The median value is reported as the thickness in inches of the material. The low load density of a material is determined by the following calculation:
Low Load Density g/cc = basis wt. in R/m2 X 0 0000394 ^ thickness in niches
The center ply 6 is preferably made from a nonwoven web of any appropriate super fine melt-blown, long fibered material. Again, polypropylene is preferred, the center ply 6 being a low density, lightly bonded ply having a composition comprising primarily linear polypropylene and having a basis weight of from about 20 to about 60 g/m2 and preferably about 30 g/m2. Again, the filament diameter should be from about lto about 8 microns. The ply 6 should be characterized by a tensile strength less than 1.5 lbs./in. in both the machine and cross machine directions; an Elmendorf tear strength of from about 80 to about 300 g. and preferably 150-300 g.
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