US 3523535 A
Description (OCR text may contain errors)
United States Patent Inventors Appl. No. Filed Patented Assignee lngemar Liss-Albin Croon Alfredshem, Sweden;
Nils Verner Blomqvist, Ornskoldsvik, Sweden Aug. 15, 1967 Aug. 1 l, 1970 continuation-impart Ser. No. 606.956, filed Jan. 3, I967,
Moo ch Domsj'd Aktiebolag Ornskoldsvik, Sweden 2 Limited company TAMPON FOR DENTAL AND CATAMENIAL USE 5 Claims, 2 Drawing Figs.
Primary Examiner Charles F. Rosenbaum Attorney-lanes and Chapman ABSTRACT: A composite tampon is provided comprising an absorbent layer of cellulose pulp fibers, preferably cellulose fluff fibers, enclosed within a wrapper layer which can be a nonwoven material, or a laminate between nonwoven material and cellulose pulp tissue.
TAMPON FOR DENTAL AND CATAMENIAL USE This application is a continuation-in-part of Serial No. 606,956, filed January 3, 1967 now abandoned.
This invention relates to a tampon having an absorbent layer composed of cellulose pulp fibers, and particularly cellulose fluff fibers, and more particularly to tampons made of absorbent cellulose pulp fibers less than about 5 mm. in length, and enclosed within a sheath of non-absorbent fibrous woven or nonwoven material or a laminate between nonwoven fabric and cellulose pulp tissue.
It is generally accepted that a satisfactory tampon must have a sufficient initial stiffness and rigidity to facilitate its insertion in the body cavity, but at the same time should be sufficiently soft or softenable in the body cavity so that its pressure is acceptable there without irritation. The tampon must also have a high capacity for absorption of the desired body fluids, and it must be capable of absorbing the desired body fluids without disintegration, so that when it is necessary to remove it, it can be removed intact.
After many years of development and evolution, the tampon in common use today is made of absorbent cotton fibers, usually in the form of cotton wadding, which is wound into the form of a cylinder, with the aid of reinforcing material, and finally provided with a gauze covering that resists disintegration in the body cavity. However, it must be conceded that as a practical matter, tampons of this type can nonetheless liberate cotton fibers in the body cavity, and they also have a tendency to become far too soft, and lose their shape, upon absorption of an appreciable amount of body fluids. Typical tampons of this type are described in U.S. Patents Nos. 2,099,931, dated November 23, 1937 to Fourness, and 2,900,980, dated August 25, 1959, to Harwood. Tampons are also known which consist altogether of absorbent cotton fibers, the outer layers of which are bonded together with glue. These tampons also show the disadvantages mentioned above.
It has been suggested that synthetic mainly nonabsorbent fibers such as acetate rayon be employed in place of cotton. Such fibers are not capable of absorbing aqueous fluids, and consequently are not softened by body fluids. However, a large proportion of the absorbent capacity of a tampon made of cotton fibers is due to the absorption by the fibers them selves, and consequently, tampons made of acetate rayon, or other non-absorbent synthetic fibers of this type, have an insufficient capacity for absorption to make them generally acceptable as a substitute for cotton fiber tampons. It has also been suggested that fibers of regenerated cellulose (rayon staple fibers) be employed in place of cotton. Such tampons show, however, the same disadvantages as the cotton tampons described above.
In accordance with the invention, tampons are provided in which the absorbent material consists essentially of cellulose pulp fibers that are less than 5 mm. in length. Such fibers due to their short length give a dense, relatively noncompressible mass. The fibers are quite absorbent. The absorbent material composed of these fibers is enclosed within a wrapper or sheath of fibers having a high wet strength, such as high wet modulus viscose or acetate rayon fibers, associated as a nonwoven fabric. This sheath accordingly, is relatively unaffected by body fluids. The result is a tampon that although highly absorbent is more dimension-stable than prior tampons, and is therefore not readily susceptible to disintegration after absorption of body fluids. Moreover, the wet strength of the fibers of the wrapper makes it possible to employ a synthetic resin binder therefor that is also unaffected by body fluids, thus substantially preventing disintegration of the wrapper while in use in the body cavity. This means that the cellulose fibers of the absorbent layer can be prevented from detachment from the tampon in use.
In a preferred embodiment of the invention, the cellulose pulp fibers are enclosed within a sheath composed of a laminate between nonwoven fabric and cellulose pulp tissue. Such a sheath has superior strength and durability.
0 is folded or rolled lengthwise, forming a bilayered column with the wrapper as the outer layer forming a seam, which is then bonded. If the fiber layer and the wrapper sheet are continuously fed, it is possible to form an endlessly elongated column of absorbent cellulose pulp fibers with the wrapper constituting the outer layer, and this can be cut into any desired length to form the finished tampon.
If a multi-ply sheath is employed, as in the preferred embodiment described above, the multiple plies thereof are brought together preferably with heat and pressure before they are brought into contact with the layer of cellulose pulp fibers. The tampon is then completed using the described procedure and apparatus.
The composite tampon that is obtained by this process is a cylinder, comprising the absorbent layer of cellulose pulp fibers on the wrapper layer wound about itself, with the wrapper layer outermost, so that it serves as a protective outer layer. The wrapper layer also serves as a reinforcing layer for the tampon, and imparts rigidity. [f the composite is tightly wound, the absorbent layer can be compressed within the wrapper, increasing the density of the composite. lt is preferred that the density be within the range from about 0.05 to about 0.3 g/cc., preferably from 0.1 to 0.2 g/cc., which illustrates the high degree of fiber packing that characterizes the tampons of the invention.
The tampon will usually be cylindrical in cross-sectional configuration, but of course any configuration can ,be fashioned, such as polygonal, square, rectangular, or elliptical, according to the end use intended. A cylindrical composite is preferred. It is, of course, also possible to compress only the absorbent layer of cellulose pulp fibers,and then in another step enclose this material in an outer encircling wrapper. of wet strength fibers.
The apparatus comprises in combination, a porous base, preferably in the form of an endless porous belt, means for laying down cellulose pulp fibers upon the belt and forming a layer thereon, means for applying suction upon the layer on the belt from below and a small air pressure upon the layer on the belt from above, so as to hold the layer on the belt, means for bringing a sheet of wrapping material into contact with the fiber layer, means for folding or rolling the composite or wrapper and fiber layer longitudinally to form a column, means for sealing and bonding the lengthwise seam of the resulting column, and means for cutting the column into lengths to form the tampon.
lt is important that the cellulose pulp fibers employed in forming the absorbent layer of the tampons of the invention be less than 5 mm. in length. Fibers that are longer than this are too long to form a dense relatively non-compressible layer They are also subject to breaking under wet conditions and therefore give a weaker structure. It is preferred that the pulp fibers be less than about 3 mm. in length. For maximum density and non-swellability, at least 40% of the weight of the fibers should be less than about 0.8 mm. in length.
Such cellulose pulp fibers are obtained by disintegration of wood pulp in sheet or flash dried form, using mechanical disintegrating apparatus. Such processes are well known, and form no part of the instant invention. The process and apparatus must be of the type that separates the fibers in an efficient way without cutting the fiber too much. Over-cutting the pulp fibers results in cellulose flour which is unsuitable for this invention, and the proportion of which is therefore held to a minimum.
As a source of such cellulose pulp fibers, there can be used any pulping wood, such as spruce wood, pine wood, hemlock wood, fir wood, birch wood, and other types of coniferous and hard woods.
The cellulose pulp fibers that are preferred for use in the invention are of the type called fluff. These are obtained by disintegrating chemical cellulose pulp prepared by the sulphate or sulphite method in such a way that the fibers are set free from the pulp while at the same time avoiding the formation of fiber bundles or knots and cutting of the fibers. This disintegration can be carried out in a shredder or hammer mill or in a disk refiner or in an apparatus comprising a set of circular sawblades mounted on a rotating axis, or in a combination of these. For instance, the chemical pulp in the form of sheets can be first roughly dry-disintegrated in a shredder or hammer mill and then further disintegrated in a disk refiner. If the pulp is in the form of rolls, it is possible to disintegrate it directly in one step in a hammer mill. It is not necessary, and in fact it is undesirable to materially shorten the fibers of the cellulose pulp after such disintegration, and therefore the disintegration technique and apparatus used should be specially adapted to avoid this, using the known techniques.
It is preferred that the cellulose fibers fall within the following ranges of fiber length distribution, measured by the Bauer McNett method:
In fluff, the proportion of the median fraction of the fibers is somewhat greater than in ordinary chemical pulp. As a result of this difference, small as it is, in the distribution of fibers, fluff fibers have a higher bulk and a greater absorption than ordinary chemical pulp fibers.
Fluff fibers are rather different in physical nature from fibers of cellulose pulp tissue which are also obtained from cellulose pulp, but are prepared by a different process. Cellulose pulp tissue are obtained by placing sheets or bales of chemical or mechanical cellulose pulp in hollanders, where the pulp is beaten with water. The suspension obtained can then be stored and is next transported to beaters, after dilution to a pulp concentration of 0.5 to 1.5%. The beater can be a disk refiner, or a Jordan mill employing a rotating cone, and the beating is mild. After the beating, water is removed from the suspension in an uptaking machine. The fiber length distribution of the resulting tissue fibers is similar to that of fluff fibers, but the product is paper-like, and not bulky. The absorption capacity of tissue fibers is from 1/3 to H4 that offluff fibers.
Consequently, cellulose pulp tissue are not desirable in the absorbent layer of tampons in accordance with the invention, because of their low absorption capacity.
Cotton cellulose fibers differ materially from cellulose pulp fibers. They are materially longer, greatly exceeding 5 mm. in length. Because of their length, they are subject to breakage and rupture, and give tampons which are not as rigid as those obtained using cellulose pulp fibers. Moreover, they are more expensive. Consequently, they are not employed in the tampons of the invention.
The wrapper or outer layer can be any porous sheet material that has a high wet strength. By high wet strength according to the present invention is meant from 3 to 6 kilograms per 50 millimeters strip in the length direction and from 0.3 to kilogram per 50 millimeters strip in the transverse direction as measured according to TAPPl 456 m-49. Nonwoven mats, sheets and fabrics of nonabsorbent synthetic fibers or impregnated or coated natural fibers are preferred wrapper materials. The nonwoven materials are cheap, and would normally be employed. These materials can be made of any type of synthetic, fiber, such as acetate rayon, nylon, polyacrylamides, polyvinyl chloride, polyvinylidene chloride, terephthalic acid-ethylene glycol polymers (Dacron), poly-acrylonitrile (Orlon and Vinyon N), polyethylene, and polypropylene, or of natural fibers impregnated or coated with a sufficient amount of such materials to render them non-absorbent or of high wet modulus viscose rayon fibers.
For greatest strength and resistance to disintegration in use, the fibers of the nonwoven wrapper material are preferably bonded at their points of crossing by a synthetic resin binder material such as a thermoplastic or thermosetting resin. The amount of binder that is employed should not materially reduce the porosity of the wrapper, nor should the resiliency thereof be greatly affected, since an unduly rigid wrapper material is hard to roll and handle in the processing. Flexibility of the wrapping material is desirable and has very little effect on the stiffness of the final product, since the relative noncompressibility is obtained because of the nature of the cellulose pulp fiber layer. This layer can be rolled very tightly, and consequently is responsible for the relative rigidity and noncompressibility of the tampons of the invention as compared to the known products.
Among the binder materials that can be used are polyvinyl chloride, polyethylene, polyropylene, nylon, polyacrylonitrile, ethylene glycol-terephthalic acid copolymers, polyvinyl acetate, copolymers of vinyl acetate and vinyl chloride, polyvinyl butyral, polytrifluorochloroethylene, urea-formaldehyde, melamine-formaldehyde, phenol-formaldehyde, and alkyd resins. It is very suitable to use a binder comprising the same material as the fibers. These can be formulated into binder compositions of conventional type, including plasticizers, pigments, and fillers. Such compositions are well known, and form no part of the instant invention. In all cases, however, the binder composition should be resistant to and insoluble in body fluids.
A multi-ply wrapper can have superior strength and durability, and is preferred in many instances. Two or more plies of the same or different materials can be employed. Nonwoven fibrous materials can be used.
One preferred type of multi-ply wrapper is made of an outer layer of nonwoven fibrous material, as described above, and of one or more inner layers of cellulose pulp tissue. Cellulose pulp tissue is made as previously described, and is distinct from fluff fibers because of the different preparatory procedure. It is used to strengthen the wrapper, and not to impart greater absorbency, nor does it form a part of the absorbent fluff fiber layer.
The cellulose pulp tissue can be formed as separate tissue paper layer and then combined with the nonwoven material with heat and pressure to form the wrapper. Bonding of the tissue fibers to the outer nonwoven ply is desirable. Any of the binding agents mentioned above can be used for this purpose.
The cellulose pulp tissue ply and the outer plies can each have a thickness ranging from 0.05 mm. to about 2.5 mm. The wrapper overall can have a thickness of from about 0.1 mm. to about 5 mm. The tampons absorbent fluff fiber layer will have a diameter of from three to fifty times the thickness of the wrapper.
The tampons in accordance with the invention can easily be prepared on any base by laying down a layer of the cellulose pulp fibers, and then rolling up the layer into an elongated column. Preferably, the layer is laid down on the wrapper, and the composite folded together so that the wrapper layer is outermost. This operation can be conducted manually or by machine. The lap at the outer edge of the column that is thus obtained is then bonded, so as to prevent unrolling. However, for economy of production costs and a greater rate of production, it is preferred to prepare the tampons by a continuous process, using apparatus provided.
FIGURE l represents a side view of a typical apparatus designed to form an elongated continuous cylinder that can be cut in sections according to the length of tampon desired.
FIGURE 2 represents a perspective view of a tampon produced by the apparatus of FIGURE 1.
The apparatus includes a disintegrator l for pulp sheets of the hammer mill, disk refiner, or circular sawblade type, capable of disintegrating the pulp sheets into separate fibers less than 5 mm. in length. Pulp 2 is continuously supplied to the disintegrator through line 3. In operating the disintegrator, air is sucked in together with the pulp sheets, at the same time causing compression of the air on the outlet side 5 of the disintegrator. The air entrains the cellulose pulp fibers 6 as they emerge from the mill, carrying the fibers, now airborne, through line 7 to an endless wire mesh belt 10. The belt passes over drive rolls 8 and idler rolls 9, which are adjustable to control belt tension. The eductor fan 11 below the belt draws the air across the belt. The diameter of the mesh openings of the belt, which can be made of stainless steel wire mesh, is less than 0.1, preferably from 0.05 to 0.01 mm., which corresponds to from about 150 to about 800 mesh, so that the fibers are filtered out from the air as it passes across the belt, and are deposited on the belt in the form of a layer 12, usually I to mm. thick, which is held firmly down on the belt under the air pressure of the air stream passing to eductor fan 11. The rate of flow of the air stream in the line, and the rate of production of fibers by the disintegrator, are matched with the travel speed of the endless belt, so that a uniform layer of cellulose pulp fibers is formed on the belt. This layer serves as the absorbent layer of the tampons of the invention, as is best seen in FIGURE 2.
A sheet of wrapper and reinforcing material, in this case, a nonwoven highly porous gauze 13 made of acetate rayon fibers bonded together by a cellulose acetate binder, provided, if desired, with a laminate between the nonwoven fabric and cellulose pulp tissue, is fed from a rolled source of supply 15 over an idler roll 16 and tensioning roll 17, and then over three guide rolls 18 to the top of an endless feed belt 21 running over drive roll 19, and idler roll 20. Roll 19 can be adjusted to control tension. Directly above the belt 21 is a second endless belt 22, spaced therefrom by a gap equal to or slightly less than the thickness of the layer 12 plus the gauze 13. Belt 22 is driven by roll 23 at the same travel speed as belt 21, and passes over two guide rolls 24 and a tensioning roll 25.
The wrapper material 13 is arranged to enter the nip between the belts 21, 22 beneath the layer 12 of cellulose pulp fibers which is fed in from belt 10. The composite layer of wrapper material and cellulose pulp fibers, slightly compressed if desired, in the nip between belts 21, 22, then passes through the former die 28, where the composite is folded over on itself, wrapper layer outermost, into a tampon cylinder 30, with the ends of the lapped sheet on top, forming a longitudinal seam 31 (best seen in FIGURE 2) running the length of the cylinder. The kissing roll 32 applies a band of adhesive 33 to the longitudinal seam, and sealing is completed by the heated pressure rolls 35, 36, which apply sufficient heat and pressure to effect the bonding of the seam by the adhesive. This secures the cylinder against unwinding. The knife blade cutter 37 is provided to cut the cylinder into the desired size of tampon.
The apparatus as illustrated is intended to form tampons that are cylindrical in cross-section. If a different type of crosssection or configuration is desired, all that is necessary is to substitute a suitably shaped forming die for the cylindrical forming die 28. Thus, for example, a rectangular die will form a rectangular tampon, an elliptical die will form an elliptical tampon, and so on. The tampon will be set in this configuration by the adhesive.
An adhesive is not needed to seal the longitudinal seam, if the binder and/or some or all of the fibers of the wrapper are softenable by heat. In this case, the temperature of the pressure rolls is elevated to a point at which the fibers are softened, so that the pressure rolls will bond the fibers at the lapped ends of the sheet together, forming a seal. The bonded fibers when they are hardened will retain this position. Moreover, the fibers will also be set in the configuration of the tampon. In this way, it is possible to produce a tampon having any desired cross-sectional configuration, that will retain this configuration in use.
The following examples in the opinion of the inventors represent preferred embodiments of this invention.
EXAMPLE 1 Employing the apparatus of FIGURE 1, tampons were prepared made of cellulose fluff fibers from spruce wood pulp, prepared by the sulfite process. The spruce wood pulp in sheet form was fed to a hammer mill disintegrator, where it was reduced to fluff.
The fluff fibers had the following fiber length distribution:
These fibers were made airborne, and carried thus from the disintegrator to a stainless steel 320 mesh wire belt, where they were laid down to form a mat, 8 mm. thick. This mat was brought into contact with a nonwoven wet strength viscose rayon gauze 0.1 mm. thick, having an average pore size of microns, and bonded by a polyvinyl acetate binder. The resulting composite was tightly pressed together, and then formed longitudinally into a tightly wound cylinder. A polyethylene emulsion adhesive was applied to the longitudinal seam of the resulting cylinder, and this was set by heat and pressure, so as to seal the seam and retain the cylindrical configuration. The cylinder was then cut into one inch lengths, to form tampons.
The wet strength of the tampons thus prepared was determined by subjecting them to the following test procedure.
The tampon was transferred with a pair of nippers to the perforated plate of a Buchner funnel, connected at the bottom to a niveau tube placed at an equal level to the Buchner funnel. Water was added with a burette to the niveau tube, so that the level of water was at the upper part of the perforated plate of the Buchner funnel. By means of capillary forces, water was then absorbed into the tampon. The amount of water that was absorbed was noted, as well as the physical condition of the tampon after the water had been absorbed.
The tampon of the invention absorbed 9.7 g. of water per gram of tampon. The tampon retained its shape and its strength thereafter.
Using the same test, a commercially available tampon was evaluated composed of rolled cotton, the outer side of which was glued together with a water-soluble glue. This tampon swelled and burst after absorbing 10.2 g. of water pe. gram. Another tampon of this type, but from a different manufacturer, was tested. This one swelled, and then went to pieces completely, so that it was impossible to determine the amount of water absorbed.
It is apparent from the results of this test that the tampon of the invention is quite desirable for use in dentistry. It is capable of absorbing the saliva of the mouth during surgical operations. The other commercially available tampons tested would have been unsatisfactory for this purpose, because bundles of fibers would be separated from the tampons, and probably would find their way into the wound, after which it would be necessary to pick out the fibers with a pair of nippers.
EXAMPLE 2 layer and the mat were each 0.1 mm. thick, and the layer of cellulose fluff fibers was 6 mm. thick. This was wound up longitudinally, to form an elliptical tampon with the polyethylene mat outermost, and the entire mass subjected to heat and pressure at a temperature just above the softening point of the polyethylene fibers of the wrapper, so as to bond the lapped edges of the longitudinal seam together, and retain the elliptical shape. These tampons were cut into lengths inches long, for use as catamenial appliances.
It is apparent from the preceding disclosure that in accordance with the invention tampons can be provided for any medical or surgical use. The cellulose pulp fibers that are employed in the absorbent layer have bulk and very high absorption capacity, and because of its construction and theshort length of the fibers, the tampon retains its rigidity and strength even after absorption of a considerable proportion of body fluids.
1. A shaped relatively rigid composite tampon that retains its rigidity and strength even after absorption of a considerable proportion of fluid, comprising a compressed absorbent layer which is wound about itself and which consists essentially of cellulose fluff fibers that are less than 5 mm. in length, and a wrapper holding the absorbent layer under compression and tightly enclosing the absorbent layer in a sheath whose edges are lapped in a bonded seam extending longitudinally of the tampon and comprising a nonwoven, water-permeable fibrous mat formed of fibers having a high wet strength bonded together by a bonding agent.
2. A tampon according to Claim 1 wherein the density of the compressed absorbent layer is within the range from about 0.05 to about 0.3 g. per cc.
3. A tampon in accordance with Claim 1 in which at least 40% by weight of the cellulose pulp fibers are less than 0.8 mm. in length, and the remainder are less than about 3 mm. in length.
4. A tampon in accordance with Claim 1, in which the wrapper layer is a multi-ply layer.
5. A tampon in accordance with Claim 4, in which the inner wrapper layer is a cellulose pulp tissue layer.