US 3072511 A
Description (OCR text may contain errors)
Jan. 8, 1963 K. J. HARwooD 3,072,511
LAMINATED SHEET MATERIAL Filed Sept. 30, 1954 2 Sheets-Sheet 1 @w MVM Jan. 8, 1963 K. J. HARwooD LAMINATED SHEET MATERIAL 2 Sheets-Sheet 2 Filed Sept. 50, 1954 Mwvw @new Z50/wood.
United States Patent tlice assignments, to Kimberly-Clark Corporation, a corporation of Delaware Filed Sept. 30, 1954, Ser. No. 459,487 2 Claims. (Cl. 154-46) This invention relates to improvements in cellulosic products in the nature of laminated sheeting suitable for the production of towels, wiping material, bibs, aprons, and many other products, especially products which benefit by a capacity for fluid Aabsorption although the latter is not a necessary attribute of all products which may be made of the improved material.
lThe main objects of the present invention are to provide low cost cellulosic products of the above indicated character in which substantial strength and dimensional stabiilty are -built into the products in their entireties so that flimsy and weak components may be successfully employed in producing products which, in their normal use, are subjected to tensile and other forces which would normally break or disrupt the weaker individual components; to provide such products which may be folded and rumpled like a conventional textile dusting or wiping cloth without impairing the usefulness of the product for its intended purpose; to provide a reinforced product which compares favorably with non-reinforced material such as cloth in respect of softness and smoothness, and to provide cellulosic products such as toweling, wiping and dusting material, and similar sheet material which may be produced and sold at low cost to make economically feasible, limited-use disposable products for the indicated and other purposes. In general, it is the object of this invention to provide improved cellulosic products of the character indicated.
Other objects and advantages of the invention will be understood by reference to the following specification and accompanying drawings wherein there are illustrated certain selected products embodying selected forms of the invention together with schematic representations of variousmethods for producing the products or elements thereof. Y
In the drawings: Y
FIG. l is a plan on a somewhat enlarged scale of one form of an improved, reinforced cellulosic wadding product; Y j
FIG. 2 is a plan on an enlarged scale of a netflike web or fabric constructed of` threads which typilies one form of reinforcing element which is employed in the product represented in FIG; 1; r
FIG. 3 isa cross-section on the line 3--3 of FIG. 2;y i' FIG. 4 is a typical section of the material shown in FIG. l, the view being representative of the formation in any section such as indicated by the line 44 of FIG. l, and being onl an enlarged scale with thickness exaggerated to facilitate illustration;
FIGS. 5 and 6 are, respectively, schematic representa- `tions of methods used in producing the product shown,
in FIGS. l to 4 inclusive. r
` The fabric represented in FIG. 1 comprises four plies 1, 2,3, and 4 respectively, of creped tissue paper or socalled cellulosic wadding. Although heavier plies may be used, those presently preferred are individually very 072,511 Patented Jan. 8, 1963 thin and tenuous, `and highly porous. The presently'p'referred tissue plies are of such light weight and are so tenuous that they have but little utility except that of a component in a product in which the tissue is supported by other tissues or other material. However, for some purposes heavier weight and stronger material may be used. Between the innermost plies 2 and 3 of said wadding there is a reinforcing and bonding web, 5 formed of interwoven or of cross-laid, lengthwise and transverse threads, the web being in this instance, a cross-laid web consisting of two sets of spaced parallel threads dis posed in face-to-face relation, one set being wholly on one side of the other set. These sets of threads are adhesively bonded to each other at the crossings of their threads. Parallel thread arrangement is not essential and may give way to non-parallel threads including various arrangements such as sets of wavy or undulating threads which threads may extend in one general direction without necessarily being parallel to one another.
Adhesive carried by said web 5 serves to bond to-V gether the wadding plies 1 to 4 inclusive so as to integrate the describedy components into a unitary sheet. However, it is not essential that the adhesive for this purpose be carried" by said web 5; adhesive may be applied in any suitable pattern and manner to one of the inner plies 2 or 3 in an amount sufficient to produce the required bonding of the plies, or adhesive may be printed on the outside of the sheet in any suitable pat,- tern and in such an amount that it will penetrate the sheet to produce the desired bonding of the wadding plies to each other;
One form of the web 5 is represented in a somewhat enlarged scale in FIG. 2, the lengthwise threads being designated 6V and the crosswise threads 7. These threads 6 and 7 are of multi-filament, low twist construction so that each thread is very flexible, soft, and smooth surfaced. Long, unbroken, smooth surfaced, rayon or other extruded filaments are preferably used to make the threads. Flexibility and softness of these threads is such that although the twisting of the filaments together .tends initially to form the same into threads of cylindrical crosssection, the threads readily assume a somewhat flattened or oval form as shown at 8 in FIG. 3. This distorted cross-sectional shape occurs as an incident to the passage of the thread under slight tension through or over guiding elements during the final stages of its fabrication and as an incident to the winding of the threads into spools or'reels. When the threads 6 and 7 are assembled into relative transverse relationship as shown in FIG.` 2, said threads tend to fan out into flattened intersecting portions as represented at `9 n FIGS. 2 and 3, and this flattening may be subsequently increased by subjecting the product containing the cross-laid thread web to a brushing, rubbing or similar working operation,or to la calendering or similar pressing operation. As shown in FIG. 3, the thread 7 is ,flattened to a substantially widened but thinned intersecting portion 10 and the thread 6 is similarly flattened into a widened thin portion 11 which `engages, the adjacent flattened portion 1 0 of the other thread. This flattening occurs to some extent merely as an incident tof the deposition ofthe threads 7 in cross-laid relation to the thread 6 but, as already indicated, this flattening effect is substantially increased by a calendering operation which is employed either as a finishing operation for the cross-laid thread web or for the laminated product of FIG. 1, or both.
The multi-tilament threads 6 and 7 have a denier within the range of about 30 to 150, embodying from 2 to 150 continuous filaments, and a twist less than 6 per inch. The respective filaments in the threads are of a denier within the range of about l to l5. In one practical embodiment, the cross threads 7 were of 100 denier comprising 40 individual filaments with a twist of about 4 per inch. The lengthwise threads 6 were of 75 denier, having 30 individual filaments with a twist of about 21/2 per inch.
The cross-laid thread web of FIG. 2 may be produced by any suitable cross-laying apparatus, one form of which is' schematically represented in FIG. 5. As there shown a series of threads 6 are guided over an adhesive applying roller 12 which rotates in a bath of suitable adhesive contained in a tank or trough 13. The threads receive a coating of adhesive from the roller 12 and are guided into circumferentially spaced relation around an elongated cylindrical mandrel 14, a suitable guiding device 15 beingV provided for so guiding the threads 6. Depending upon the type of adhesive used, provision may be made to dry or partially dry the adhesive on the threads to prevent wet adhesive from gumming up the guide 15 or mandrel 14, and suitable provision such as heating or moistening means may be provided for reactivating the adhesivey at the required time to make such adhesive useful for bonding the threads together and other components to the threads 6.
One or more spools 16 of thread are supported by a rotatably driven annulus 17 which is so arranged that the spools 16 will be carried around the mandrel so as to wind one or more threads 7 around the mandrel and around the lengthwise extending threads 6 which are being propelled along said mandrel. The adhesive carried vby said threads 6 serves to anchor the cross threads 7 in place on the lengthwise threads 6. The tube of net-like material thus formed is slit longitudinally at one side by a suitable slitting device represented at 18, and the resulting net-like sheet is distended into Hat Web form as represented at 19. The tension under which the cross threads 7 are wound around the longitudinal threads and the mandrel, may be sucient to contribute somewhat to theV above described iiattening effect on the thread crossings. If desired, the web 19 may be passed between feed rolls which will effect longitudinal movement of the threads 6 along the mandrel, and through a suitable calendering stack to press the threads tightly together to atten their intersections as already explained and to increase the embedment of the cross threads 7 in the adhesive on the longitudinal threads 6. For some purposes, the calender stack may be heated.
The roll 12 which applies adhesive to the threads 6 may be so formed or operated that the adhesive to the threads 6 will be discontinuous as indicated by adhesivefree lengths 21 on the longitudinal threads 6 (FIG. 2). For example, the adhesive applying roll may be formed with openings or recesses which will not carry adhesive to the threads or it may be smooth surfaced and rotated at a surface speed which is somewhat slower than the speed of travel of the threads so that there will be an adhesive stretching effect as the threads leave the roll 12. Such stretching will cause breaks in the continuity of the adhesive to leave said adhesive-free areas 21 at irregular intervals. The frequency of these adhesive-free areas may be controlled to a considerable extent by varying the speed relationship between the travel of the threads and the surface speed of the adhesive applicator. These adhesive-free areas serve to retain in such areas the normal softness and tiexibility of the lengthwise threads so that the stiffening effect of the adhesive applied to said threads is held down to a practical minimum. At the same time, the cross threads 7 will be adhesively bonded to all of the longitudinal threads excepting for an infrequent occurrence of the passage of a cross thread over an adhesivefree area on a longitudinal thread. Hence, effective bonding of the cross threads to the longitudinal threads is attained even though a few crossings may remain unbonded.
For assembling the elements L1 to 5 inclusive as shown in FIG. l, an arrangement such as schematically represented in FIG. 6 may be employed.. As there shown, there is provided a continuously driven conveyor belt 22 on which the elements 1 to 15 are continuously assembled into superposed relationship, the respective elements being drawn from suitably mounted supply rolls thereof. From the assembling conveyor 22, the assembled ele ments are guided between rolls of a calender stack 23 which is adjusted to apply the desired pressure to the assemblage. From the calender stack the assembled product may be delivered to winding mechanism whereby the assemblage is wound into suitable rolls for subsequent use, or it may be subjected to additional operations represented in FIG. 6 which will presently be explained.
When the assembled web is calendered as represented at 23 in FIG. 6, or when the cross-laid web 5 is calendered before assembly thereof with the tissue plies 1 to 4 inclusive, flattening of the intersecting thread portions may be effected to such an extent that at the thread crossings, the combined thickness of the crossing thread portions is reduced to only very slightly more than the normal di ameter in the same direction of a single thread. If desired, the calendering pressure may be high enough to reduce the thicknesses at the crossings to such an extent that the thickness will not be noticeably different at the thread crossings than it is intermediate said crossings. To avoid cutting of the threads at their intersections incident to the pressure under which they are pressed together, one of the calender rolls between which the web is calendered, may be of cotton construction and the other of steel. The relatively soft cotton roll is sufficiently resilient to permit the web being calendered to be pressed partially into the roll -to prevent thread cutting. The longitudinal threads of the web are preferably on the side of the web which engages said cotton roll so that said threads can act as strippers for removing the cross threads from the cotton roll. If the adhesive on the threads is of heat sensitive character, hot calendering will aid in the iiattening effect.
The adhesive employed for bonding the threads together may be of any suitable kind having the desired properties of flexibility, water proofness, oil proofness, bonding strength, toxicity, and other characteristics to suit the end uses of the product. One type of adhesive which has general utility for the production of products such as herein contemplated and which is well suited for application by means of an applying roller, is polyvinyl acetate solution containing a plasticizer. One example of such adhesive may contain 30 percent polyvinyl acetate, 67 percent solvent, (such as commercial Solox, an alcohol preparation), and 3 percent of dibutyl phthalate plasticizer. This adhesive is one which remains flexible and which does not deeply penetrate the threads but rather tends to remain surfaced thereon, thereby avoiding stiifening of the threads and providing for effective embedmcnt of the cross threads in the adhesive. Also, it is of thermoplastic character. Adhesives of the emulsion, plastisol or organisol types may be used as may also hot melt type adhesive such as polyethylene. In general, the adhesives are usually of a moderate to high viscosity so that they will tend to remain on the thread surfaces to which they are applied and will not tend seriously to creep or spread along the surfaces of other threads which come into contact with said adhesive.
In the present instances, it is preferred that the adhesive applied to the longitudinal threads 5 be of thermoplastic character so that when the sheet material is calendered t a hot calender, the adhesive will be reactivated so as to permit it to spread over the widened surfaces of the thread intersections to thereby effect adhesive bonding over said increased-width surfaces so that highly effective adhesive bonding is obtained. At the same time, the softening or reactivating of the adhesive permits it to penetrate the adjacent wadding plies 2 and 3 and to contact the outer wadding plies 1 and 4 to thereby effect adhesive bonding of all of said elements into a unitary article. v
For a towel product, a good body is preferred and this is readily obtained in the described structure by reason of the adhesive bonding of the parts along the narrow spaced zones determined by the adhesive bearing threads 6. In one practical embodiment the threads in the netlike web are arranged in a 4 x 4 construction so that only a small percentage of the area of the web is actually adhesively bonded, such area being that which coincides with the adhesive bearing longitudinal threads 6. The areas intermediate said threads remain free of adhesive and depending largely upon the amount of moisture in v gether by parts of the wadding along the threads 6 and 7, especially along the adhesively coated threads 6, or to the consolidation of said wadding plies along said threads incident to the calendering operation, the areas 24 being unaffected by the threads and accordingly permitted to retain the relatively uncompacted condition. In one example, a calendered sheet had a thickness of .0065 inch.
If desired, the wadding plies 1, 2, 3 and 4 may be suitably treated to impart wet strength thereto but such treatments usually tend to reduce the absorbency of the wadding. F or toweling purposes a high absorbing capacity is, of course, desired so that wet strength treatment, if employed at all, should preferably be restricted to the minimum treatment required to provide suitable wet strength. The cross-laid thread fabric embedded in the sheeting serves to inpart adequate tensile strength to the sheeting in all directions so that it will not tear or pull apart, even when wetted, under normal conditions of use, and it also imparts desirable surface characteristics to the product as already explained.
rl`oweling constructed as above set forth has good body but is nevertheless very soft and flexible and has a feel which compares very favorably with a cloth face towel. The appearance of the towel incident to the design effect resulting from the presence of the square mesh reinforcing fabric is very attractive.v The threads are not visible as such on the outside of the sheeting but are evidenced on the outside by thin thread-like lines of compaction as indicated at 25 which register with the threads as an incident to the calendering operation.
'Ihe calendering of the sheet effects tiattening of the threads so that the presence thereof in the sheeting is barely, if at all noticeable, especially by feel. This deemphasizing of the prominence of the thread component is achieved by the use of small denier, soft, low twist thread which initially is less abrasive and softer than conventional spun threads, and also by treatment which causes the ber web component to be moreA or less iluffed or puffed in the areas intermediate threads. The smoothness of such a calendered sheet provides a surface which may be readily printed upon.
The very desirable body resulting from the puffed effect above referred to, and the softness and conformability of the sheet, may be amplified by subjecting the material to a creping or crinkling operation which will produce irregular creping in the sheet as indicated at 26 in FIGS. 1 and 4. This creping is somewhat irregular v in pattern and does not provide continuous corrugations extending across the width of the sheet but instead pro- Vides an irregular, transversely discontinuous, crinkled ef fect. rI'his creping may be effected by doctoring the sheet in slightly moistened condition off a rotated roll or in any other suitable manner. For example, the laminated material issuing from the calender stack Z3 in FIG. 6 may be slightly moistened by a mist-like water spray 27, guided around a rotated roll or drum 28 which may be heated to dry the web as it is doctored olf the roll as indicated at 29. The creped or crinkled web 26 may be delivered to a conveyor 30 and thence to winding or other apparatus.
The creping tends to subdue the uniform puffed pattern appearance represented at 24 in FIG. 1 and replaces it with a seersucker-like fabric appearance. This creping or crinkling increases the body of the fabric and its absorbing capacity per unit of area and also has a softer1/ing effect on the fabric, all ofv which contributes significantly to the desirability of the fabric for toweling purposes.
The described products may be used once and discarded, but they are suiciently durable -to permit more extensive use; for example, a towel made according to FIG. 1, whether or not it includes the crinkling, may be used at intervals throughout a day and then replaced with a new, clean towel, the used one being disposed of, as by burning, thereby avoiding laundering. In home use, this capacity of the towel makes it especially suited to use by children and in industrial use, it eliminates burdensome handling of cloth towels for laundering purposes as well as the laundering, while providing a towel which is much superior to conventional, single use, paper towels.
Other uses for the described laminated sheeting include bibs, apro-ns, wiping and polishing cloths, and many others which will appear from time to time.
Many Variations and changes may be -rnade in the described structures while retaining the advantages and principles thereof.
l. Laminated sheet material comprising a pair of flexible layers of non-Woven absorbent material, each of said layers including a plurality of plies of crepe tissue wadding, and an open mesh, non-woven web of crossed threads interposed between said layers, the threads of said web being of 10W twist, continuous multi-filament construction, said threads having a twist less than 6 turns per inch and a denier of from about 30 to 150 with the filaments having a denier of from about l to 15, and the threads of said web which extend in one direction being coated with the adhesive to thereby bond such threads to the threads extending transversely thereof at their crossings and to bond said Web to said layers of absorbent material, and said thread web and tissue layers being calendered into intimate face-to-face engagement, the low twist and denier of said threads providing for easy Hattening of the threads without appreciably detracting from the ilexibility and softness of said absorbent layers.
2. Laminated sheet material comprising a pair of flexible layers of non-woven absorbent material, each of said layers including a plurality of plies of crepe tissue wadding, and an open mesh, non-woven web of crossed threads interposed between said layers, the threads of said Web being of low twist, continuous multi-filament construction, said threads having a twist less than 6 turns per inch and a denier of from about 30 to 150 with the filaments having a denier of from about l to 15, and the threads of said web which extend in one direct-ion being coated with the adhesive to thereby bond such threads -to the threads extending transversely thereof at their crossings and to bond said web to said layers of absorbent material, said transverse threads being essentially free of adhesive except at said crossings, and said thread web and tissue layers being calendered into intimate face-toface engagement, the low twist and denier of said threads provi-ding for easy flattening of the threads without appreciably detracting from the flexibility and softness of said absorbent layers.
References Cited in the leof this patent UNITED STATES PATENTS To-les Deci 1, 1931 Rowe Sept. 3, 1940 Jackson Dec. 23, 1941 lournvessy et all. Sept. 8, 1942 Voightman Sept. 8, 1942 Carlson Sept. 16, 1952 Maynes May 4, 1954 Aher et al June 8, 1954 Holland Dec. 7, 1954 Carlson Oct. 4, 1955 Chadwick et al Nov. 19, 1955 Stevenson Mar. 20, 1956 FOREIGN PATENTS Great Britain Mar. 25, 1937 Great Britain July 8, 1953