US 3627621 A
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Description (OCR text may contain errors)
United States Patent  Inventor William L. Mowers Oshkosh, Wis.
 Appl. No. 876,864
 Filed Nov. 14, 1969  Patented Dec. 14, 1971  Assignee Kimberly-Clark Corporation Neenah, Wis.
 CROSS THREAD REINFORCED NONWOVEN MATERIAL 3 Claims, 11 Drawing Figs.
 US. Cl. 161/59, 156/179, 161/60, 161/129, 161/148, 161/156  Int. Cl B32b 3/28, B32b 5/12  FieldofSearch 161/57,58, 59, 60, 148, 156, 128, 129, 170
 References Cited UNITED STATES PATENTS 2,902,395 9/1959 Hirschy et a1 161/143 X 3,424,643 1/1969 Lewis, Jr. et al. 161/59 X Primary ExaminerRobert F. Burnett Assistant Examiner-Raymond D. Linker, Jr. A!!urneyWolfe, Hubbard, Leydig, Voit, & Osann Ltd.
9/1969 Bassett 12/1969 Sokolowskietal.
.ABSTRACT: A cross thread reinforced nonwoven material having highly oriented fibers therein and the method of making same are disclosed. A highly oriented web or film and a spaced-pattern layer of adhesive are introduced to a crosslayer apparatus where reinforcing threads are deposited on the web with the threads disposed in spaced-apart parallel relation extending across the highly oriented web or film and partially embedded in and held in such relation by the adhe I sive of the spaced-pattern layer at locations where the adhesive extends between the web and the threads. The material may also include layers of cellulose wadding on one or both faces of the cross thread reinforced fiber web.
PATENTED DEC 1 41971 SHEET 1 [IF 3 PATENTEDDECMIQ?! 3.627.621
SHEET 3 [1F 3 The present invention relates generally to nonwoven materials and more particularly concerns thread reinforced nonwoven materials and methods of making same.
In copending Sokolowski et a1. application Ser. No. 546,067, filed Apr. 28, 1966, now Pat. No. 3,484,330 there is disclosed a nonwoven material including outer layers of cellulose wadding and inner layers of highly-drafted fibers angularly disposed to each other. A spaced-pattern layer of adhesive is disposed between each fiber layer and its adjacent wadding layer with the fibers in each fiber layer partially embedded in and held by the adhesive of its adjacent adhesive layer and partially embedded in and held by the adhesive in the other adhesive layer where it extends between the fibers of its adjacent fiber layer and with a portion of the adhesive in both adhesive layers joined where the adhesive patterns are superimposed.
As mentioned in the above-identified Sokolowski et al. application, one method of forming such a cross-laid, nonwoven fabric is to first form two separate components such as disclosed in U.S. Pat. No. 3,327,708 and then to cross-lay the two components by hand, or by suitable cross-laying apparatus such for example as is shown and described in U.S. Pat. No. 2,841,202. This results in the fabrication of a nonwoven fabric of high strength, good flexibility and sofi hand and feel which is especially suited for single or limited use, disposable fabrics.
ln following that method in practice, however, certain operational difficulties are encountered which restrict the output speed of the cross-laying apparatus. One of these difficulties, namely, the tendency of the cross-laid components to fold back along their leading edges incident to the calendering operation, can be eliminated by providing a third helical wrap on the cross-layer mandrel and introducing the machine direction web in registry with the carrier belt as it travels over this third helical wrap and before slitting the cross-laid component previously applied directly to the cross-layer belt as disclosed in copending Anderson application Ser. No. 803,175, filed Feb. 28, 1969. Even so, it is still necessary to preform the web component to be crosslaid and due to the surface area and windage of supply material in such an apparatus the output speed is restricted as compared to a threadtype cross-layer as for example as is also described and illustrated in U.S. Pat. No. 2,841,202 and in U.S. Pat No. 3,025 ,196. Also, the preceding methods generally produce a visible overlap or joint along each edge of the cross-laid components.
SUMMARY OF THE INVENTION The foregoing difficulties are eliminated according to the present invention by cross-laying spaced-apart reinforcing threads onto a highly drafted fiber web component and utilizing the adhesive of the fiber web component for bonding the threads to the fibers where they cross one another in the presence of the adhesive. Creped tissue, carded webs, spread tow, plastic films or split film networks, highly oriented in the direction of helical travel, may be substituted for the highly drafted fiber web is drafted and deposited on a spaced-pattem layer of adhesive printed either on a release coated carrier belt or on a web of cellulose wadding carried in a multiple helical path of a thread cross-laying apparatus. Preferably the webs are carried through the apparatus by a helically traveling belt. The cross threads are then pressed into and embedded in the adhesive bonding the drafted fibers where it extends between the fibers. Before cutting the cross threads another elongated medium which may be edge control threads, another sheet of wadding or even another web component including highly drafted fibers is introduced to imprison the cross threads against the fibers of the first fiber web component.
While the preferred method combines the fiber drafting and thread cross-laying operations with a fresh adhesive system, the invention also contemplates reactivation of the adhesive used to bond and stabilize drafted fiber web components which have previously been made and wound on supply rolls. Moreover, provision is made for combined operations which utilize both fresh and reactivated adhesive.
Other objects and advantages of the invention will become more readily apparent upon reading the following detailed description and upon reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:
FIG. 1 is a schematic perspective view of a cross-laying apparatus for carrying out the method of the present invention;
FIG. 2 is a plan view on a somewhat enlarged scale of one form of the improved material with sections of individual layers broken away to show the multicomponent construction;
FIG. 3 is an enlarged and somewhat exaggerated cross section of the material shown in FIG. 2; and,
FIG. 4 to FIG. 11 are alternately plan views and cross sections similar to FIGS. 2 and 3 of other materials made according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to the drawings there is shown schematically in FIG. 1 an apparatus for forming cross thread reinforced nonwoven materials which have highly oriented fibers therein. In the illustrative apparatus, multiple slivers of textile fibers are drawn from their respective supply cans ll over a guide comb l2 and in juxtaposed relation into a draw frame 13 which comprises a series of pairs of grooved rolls l4 and 15. The rolls of each pair are driven by appropriate gearing, well known in the art, at a peripheral rate of speed faster than the rate of rotation of the preceding roll pair.
As the juxtaposed slivers pass through the draw frame 13, the individual fibers are drafted and spread out to form a flat striated web of substantially aligned fibers as indicated at 16. From the draw frame 13, the web 16 while still under tension passes under a guide bar 17 and is deposited on an elongated carrier sheet 18 on the surface of which a patterned adhesive has been applied. In the preferred embodiment, the carrier sheet 18 consists of a creped wadding sheet, which has been stretched and ironed to facial tissue softness by known means, drawn from a supply roll 20 and around guide rolls 21 and 22. An offset printing roll 23 is located between guide rolls 21 and 22 and a metered amount of adhesive is supplied to roll 23 from an intaglio print roll 24 rotatably disposed in an adhesive dip pan 25. The intaglio print roller is provided with a spaced pattern, such as the diamond pattern 28 shown in FIG. 2 and excess adhesive is wiped from the roll with a suitable doctor blade 26.
Other suitable adhesive patterns may be employed, it being' important, however, that the pattern of applied adhesive be substantially open, and that the total area occupied by the adhesive comprise not more than 25 percent of the total area of the final product, and preferably only about 15 percent or less of that area. For maximum transverse strength, the pattern chosen may be interconnected, as for example the diamond pattern of FIG. 2, in which the lines of adhesive cross each other. Alternatively, a spaced brick or open gridlike pattern, wherein the lines extend transversely of the web in spaced parallel arrangement and the adhesive in each line is substantially discontinuous, may be used. The discontinuous pattern is preferred for maximum flexibility and drape of the finished product.
The wadding 18 thus printed is drawn around guide roll 22 positioned closely adjacent the draw frame 13 and guide bar 17. The web 16 of drafted fibers impinge against the adhesive coated surface of the wadding which causes the fibers to become partially embedded in the adhesive. The wadding sheet 18 is preferably continuously subjected to tension as it is unwound from supply roll 20 and the web 16 of drafted fibers is likewise maintained under tension due to attachment with the adhesive so that substantially all of the individual fibers remain in their parallelly aligned and substantially fully extended straight condition on the wadding sheet 18. In order to insure that tension is maintained in the drafted fiber web 16 during transfer to the wadding sheet 18, the latter must, of 5 course, travel at a speed slightly faster than the discharge speed of the web 16 from the draw frame 13. The combined fiber web 16 and wadding sheet 18 are fed into a thread crosslayer apparatus 30.
The illustrated cross-laying apparatus 30 includes a generally cylindrical mandrel 31 around which an endless belt 32 is helically wound through a plurality of turns. The mandrel 30 is preferably in the form of a hollow cylindrical shell having a plurality of air discharge openings therein and the interior of the mandrel is supplied with air under pressure in order to floatingly support the belt 32 on the surface of the mandrel. In the present instance, the belt 32 makes three turns or wraps on the mandrel 31 and the belt is further supported by a plurality of guide rollers and turning bars 34-39 mounted in a suitable frame (not shown).
It will be understood that the location and disposition of the roller 34 relative to the mandrel 31 determines the approach angle of the belt 32 to the mandrel and thus the angle of the helical turns. In the illustrated embodiment roller 35 not only guides and supports the belt as it moves off the mandrel, but also drives the belt around the helical turns through suitable means (not shown). The belt also is guided by rollers 36 and 39 and turning bars 37 and 38, which are preferably of the air floating type, as it returns from drive roll 35 to guide roll 34.
A serving ring 40 is rotated about the mandrel 31 in the direction of the arrow 41 in timed relation to the helical movement of the belt 32 around the mandrel. AS the serving ring rotates, a plurality of reinforcing threads 42 drawn from respective supply cones 43 are helically wound about the mandrel 31 and the belt 32, with the threads disposed in spacedapart parallel relation and extending at a substantial angle, such as 90, with respect to the longitudinal dimension of the belt. The precise spacing of the threads and their angular orientation relative to the belt, of course, depend upon the number of threads served by the ring 40, the rotational speed of the ring relative to the belt as well as the helical angle of the belt.
' In keeping with the present invention, the reinforcing threads 42 are partially embedded in and held in their parallel, spaced-apart relation by the spaced-pattern layer of adhesive where the adhesive extends between the highly drafted fibers of the web 16 and the threads and fibers cross. Thus, each thread is adhesively attached to the fiber web at a plurality of points, as it extends across the width of the web 16.
Following the helical wrapping of the threads 42 on the fiber web 16, another web 45 is preferably introduced in registry with the belt 32 and wound about a subsequent helical turn on the mandrel 31. In the illustrated apparatus 30, the web 45 is drawn from a supply roll 46 and is trained around guide rolls 47, 48 and 49 which guide the web 45 to the mandrel in registry with the belt and the fiber web 16 as they travel around the mandrel. The web 45 thus overlies the threads 42 and imprisons the threads between the fiber web 16 and the top web 45. The top web 45 preferably makes at least one complete helical turn on the mandrel 31 and a slitter 44 is disposed along the edges of the web 45 and belt 32 to cut the threads 42 into transverse segments after they are imprisoned between the webs 16 and 45.
After the slitting operation, the belt 32 and composite web comprising the bottom wadding layer 18, fiber web 16, cross threads 42 and top web 45 travel off the mandrel 31 in the direction of the belt drive and support roller 35. The composite web is then separated from the belt 32 and in the illustrated apparatus 30 is wound around the surface of a preheat drum 50 before being directed into the nip of a pair of heated calender rolls 51 and 52.
The preheat drum serves to at least partially cure or dry the adhesive in the composite web and brings the adhesive to the desired condition for final bonding of the assembled components. The required surface temperature will depend on the type of adhesive employed as well as the length of time the web remains in contact with the heated drum surface. While various adhesives may be employed, advantages reside in the use of plastisols which, as is well known, are colloidal dispersions of synthetic resins in a suitable organic ester plasticizer. While many adhesives of this nature are known, those found particularly useful for incorporating in the product of this in vention include vinyl chloride polymers, and copolymers of vinyl chloride with other vinyl resins, plasticized by organic phthalates, sebacates, or adipates. These combinations provide a fast curing plastisol adhesive characterized by relatively low viscosity, low migration tendencies, and minimum volatility. Such adhesives remain soft and flexible after curing, can be reactivated by the application of heat and pressure, such as by hot-calendering, and insure that the resultant laminated product retains the desired softness, and proper hand and feel. Although plastisols are preferred, polyvinyl resins per se, plasticized or unplasticized, such as polyvinyl acetate, and copolymers may also be used. Other flexible adhesive may also be used, including acrylic resins such as the alkyl acrylates, and butadiene resins such as butadiene-styrene and butadiene acrylonitriles.
When using the preferred plastisol adhesives described above, the steel drum 50 is heated to a temperature of about 250 to 350 F., to advance the curing or drying of the adhesive. Hot calender rolls 51 and 52 operate at temperatures of 300-375 F. and serve to complete the curing or drying of the adhesive while firmly bonding the cross threads 42 and fiber web 16 to the bottom web 18 and top web 45. The composite web then passes over a series of cooling drums 53 and 54 prior to being wound on a takeup roll 55.
In the preferred embodiment, the top web 45 is formed of creped cellulose wadding similar to the bottom web 18. Such a material is shown, in somewhat exaggerated form, in FIGS. 2 and 3. lfdesired, the under surface of the top web can also be printed with adhesive in a manner similar to the adhesive printing of the bottom wadding layer 18. For this purpose, an offset adhesive printer, indicated generally at 60 is provided.
In another of its aspects, the present invention also contemplates the utilization of previously fabricated tissue fiber laminates 56 and 58 in place of wadding layers 18 and 45, respectively. Such laminates may first be made for example as disclosed in U.S. Pat. No. 3,327,708 and stored on supply rolls from which the material is unwound and introduced to the thread cross-layer 30,. As disclosed in copending application Ser. No. 546,067, filed Apr. 28, 1966, now US. Pat. No. 3,484,330 the adhesive in such material may be reactivated and, according to the present invention, this reactivated adhesive is utilized to bond the cross threads in the composite product. A material of this character is shown in FIGS. 4 and 5.
The present invention also contemplates the method of producing cross thread reinforced fiber webs which does not require the addition of a top layer of cellulose wadding. However, in practicing this method it is desirable to introduce holddown threads on each side of the slitter as disclosed, for example, in U.S. Pat No. 3,025,196. A cross thread rein forced tissue fiber laminate of this type is shown in FIGS. 6 and 7.
The bottom wadding layer 18 may also be eliminated if desired to produce a cross thread reinforced fiber web of the nature shown in FIGS. 8 and 9. One method to produce a nonwoven material of this character is to discharge the highly drafted web 16 of fibers directly on the release coated surface of the carrier belt 32 after it has been printed with a spaced pattern of adhesive such as by an adhesive printer indicated generally at 62. Afier the cross threads 42 are wound around the helically traveling web 16 and cut into transverse segments as described above the composite web of threads, fibers and adhesive binder is stripped from the carrier belt 32, cured on the surface of drum 50 and calendered by rolls 51 and 52. In
this instance the belt may be heated by means (not shown) to partially cure or dry the adhesive to the point where it releases cleanly from the belt.
Yet another alternative is to introduce self-sustaining fiber webs 63 and 64 of the type disclosed for example in copending application Ser. No. 498,929, filed Oct. 20, 1965, in place of the bottom wadding layer 18 and top layer 45. Here again, the adhesive originally bonding the fiber webs is reactivated to also bond the cross threads 42 and produce a product of the type shown in FIGS. and 11.
It will be apparent to those skilled in the art that many variations from the examples given may be employed without departing from the spirit of this invention. For example, the slivers introduced into the draw frame 13 may include thermoplastic fibers which, when heated, bond the other fibers and threads together. Also other types of oriented webs, especially webs which are deficient in cross direction strength, such as creped tissue, carded webs, spread tow, plastic films or split film networks, highly oriented in the direction of helical travel, may be substituted for the highly drafted fiber web if desired. Other suitable changes, modifications and variations may also be made without departing from the scope of the invention.
I claim as my invention:
1. A cross thread reinforced nonwoven material having highly oriented fibers therein comprising, in combination, a unitary, multicomponent structure which includes cellulose wadding, lightweight webs of highly drafted staple length fibers closely spaced in side-by-side relationship and in which 80 to 95 percent of the fibers are parailelly aligned in fully extended and straight condition, reinforcing cross threads, and adhesive binder; said structure comprising a top and a bottom layer of said wadding, inner layers of said fiber webs adjacent each of said wadding layers with the fiber direction in both fiber layers being disposed parallel to each other, said reinforcing threads being disposed in spaced apart, parallel relation and extending across said fibers at a substantial angle thereto, a spaced-pattern layer of adhesive disposed substantially between said top wadding layer and its adjacent fiber layer, and a spaced-pattern layer of adhesive disposed substantially between said bottom wadding layer and its adjacent fiber layer; each of said adhesive layers partially penetrating its adjacent wadding layer; the fibers in each of said fiber layers being partially embedded in and held in said parallelly aligned, fully extended and straight condition by its adjacent adhesive layer; and said reinforcing threads being partially embedded in and held in said parallel, spaced-apart relation by the adhesive in both of said adhesive layers where it extends between fibers in its adjacent fiber layer and said threads and fibers cross.
2. A cross thread reinforced nonwoven material having highly oriented webs therein comprising, in combination, top and bottom layers of cellulose wadding, a pair of lightweight webs of highly oriented fibers, a plurality of substantially parallel reinforcing threads disposed in spaced-apart relation and extending across said highly oriented fibers at a substantial angle thereto, and a spaced-pattern layer of adhesive disposed between said top wadding layer and its adjacent fiber web and a spaced-pattern layer of adhesive disposed between said bottom layer and its adjacent fiber web, the fibers in said webs being partially embedded in and held in said highly oriented condition by the adhesive of said spaced-pattern layer of adhesive, and said reinforcing threads disposed between said fiber webs and being partially embedded in and held by the adhesive of said spaced-pattern layers at locations where the adhesive extends between said fibers and said threads and fibers cross.
3. A cross thread reinforced nonwoven material having highly oriented fibers therein comprising, in combination, at least one layer of cellulose wadding, at least one lightweight web of highly oriented fibers disposed substantially parallel to the machine direction of an adjacent one of said wadding layers, a plurality of substantially parallel reinforcing threads disposed in spaced-apart relation and extending across said