US3424643A - Sheet material creped tissue product - Google Patents

Description

Jan.28,1969 M EWIS, JR, ETAL 3,424, 43

SHEET MATERIAL CREPED TISSUE PRODUCT Filed NOV. 8, 1965 Sheet of 2 F. M. LEWIS, JR., ET AL 3,424,643

SHEET MATERIAL CREPED TISSUE PRODUCT Jan. 28, 1969 Filed Nov. 8, 1965 Sheet g of2 FIG. 5

FIG. 6

United States Patent 4 Claims ABSTRACT OF THE DISCLOSURE A crepe tissue product having particular utility as a cleaning medium as in washcloths, towels and the like where a capacity for fluid retention and toughness are important. Crepe tissue sheets bound interior plies of cross-laid relatively inextensible synthetic fibers forming striated webs. Each striated web is bonded to a tissue to bridge valleys of the crepe tissue and each crepe tissue ply is creped substantially perpendicularly with respect to the striation of the web to which it is adhered and substantially perpendicularly also to the crepe direction of the tissue bonded to the other layer of striated web material.

This invention relates to the art of creped paper and, more particularly, to creped paper with a striated web reinforcement.

Creped paper is produced by a crowding of a tissue paper sheet. The crowding is effected with equipment such as a doctor blade, embossing equipment including rollers bearing a pattern, and gears or the like. Such crepe may be pulled from the paper by stretching the paper mechanically or the crepe may be lost in other ways as by wetting the sheet.

It is a purpose of this invention to provide a sheet material having highly creped paper which imparts bulk, porosity, absorbency, softness and flexibility to the product and which crepe is substantially completely retained in the use of the product even when the sheet is wetted. The product is therefore useful as a cleaning medium as in washcloths, towels, wipes, and the like.

The invention will be more fully understood by reference to the following detailed description and accompanying drawings wherein:

FIG. 1 is a view of a four ply product in accordance with the invention but with plies partially opened to illustrate the cooperative relationship of the plies;

FIG. 2 is a schematic representation in cross-section and on a larger scale of a four ply product as is illustrated in FIG. 1;

FIG. 3 is an illustration of an apparatus arrangement for producing a creped paper-striated web composite;

FIG. 4 is an illustration of an apparatus arrangement for producing a sheet material of multiple plies using composites as produced with the apparatus of FIG. 3;

FIG. 5 is a view illustrating the surface appearance of a product in accordance with the invention and portions of plies have been removed to illustrate the ply nature and relationship; and

FIG. 6 is a view of an alternative form of the product.

The invention comprises thin but relatively bulky sheet material including cellulosic crepe tissue and a body of striated web material which is low in stretch relative to the crepe tissue and is bonded to peaks of the crepe tissue. The striated web material extends transversely to the crepe of the tissue and restrains the tissue from stretching in service. Preferably, two plies of the striated web material form the inner body of the sheet and these plies of striated material are cross-laid, that is, disposed at substantially right angles. Outer plies of crepe tissue in this preferred embodiment then cover each of the striated webs and the crepe of each tissue is transverse and substantially perpendicular to the associated striated web direction.

The tissue in accordance with the invention is highly creped, having a crepe ratio of between about 2:1 to 3:1 or more. By this is meant that a tissue with a crepe ratio of 2:1 would be extended to twice its length if all crepe were removed. In contrast, the striated web material has a stretch of only about 10% or less and may suitably be nonshrinking although this latter is not a particular factor since the tendency of the product under most service conditions is to stretch. The tissue peaks are very close together, which provides for a multiplicity of closely spaced bondings between the tissue and striated web material, even though many peaks may not, in fact, be bonding points.

In one method of forming the sheet material the highly creped web is passed in substantially kiss contact with a roll dipping in adhesive so that only the peaks of the crepe are treated, the valleys and hills forming the peaks being largely untreated with adhesive. The striated Web is produced from synthetic fibers of a denier in the range of 0.5 to 3 or more, with a denier of 1.5 to 3 preferred. One method of forming such a web by a series of procedural steps, including a draw frame operation, is described in United States Patent 2,407,548 issued Sept. 10, 1946. The output of the draw frame in the instance of this present application is preferably unbonded, and the striated web is fed into contact with the treated side of the crepe tissue. No significant tension is required in the application of the striated web to the crepe tissue. The fibers or filaments of the striated web lie in aligned and substantially contacting relation so that they, in effect, cover the surface of the tissue to which they are applied. When adhesively united, the individual strands of the striated web are found to bond to closely spaced, though not necessarily adjacent, peaks of the tissue. In the preferred embodiment a composite of tissue and striated web is cross-laid with another composite of striated web and tissue to provide the product illustrated in FIGS. 1 and 2.

As shown in FIGS. 1, 2 and 5, the sheet material generally designated at 1 includes a top or outer ply of crepe tissue 2 in which the crepe is in the direction indicated by the arrow 3. The numeral 4 designates a bottom or outer play in which the crepe is in the direction indicated by the arrow 5.

It will be understood that, While the crepe as illustrated in FIG. 2 is idealized as to uniformity, the peaks or, more specifically, the hills and valleys, are very generally arranged in rows as shown in FIG. 2 at 4. The actual variations in the shape and extent of the hills and valleys designated respectively at 6 and 7 in FIG. 2 may vary widely but the overall pattern is, nevertheless, in the sheet as generally illustrated. Sheet 2 is, of course, similar to sheet 4 and, as illustrated in FIG. 2, is transversely arranged to sheet 4, surface protuberances being indicated at 8 (FIG. 2).

The numeral 9 (FIG. 2) designates the peaks which are coated with small droplets 10 of the adhesive. Some peaks, as at 9a may be out of the general plane and may be uncoated or out of contact with the web material 11. In FIG. 2 the web material 11 is perpendicularly arranged to the web material 12 as well as to the crepe of tissue 4. The web material 12 is bonded at 13 to tissue 2 similarly, as described in connection with web 11. The two webs are themselves preferably retained together by only the adhesive 10. This adhesive may be caused to flow sufiiciently under pressure and, in the case of thermoplastic adhesives heat, to unite the two striated webs.

The product of FIGS. 1 and 2 is produced as illustrated in FIG. 3. Therein at a supply roll of creped wadding is illustrated. This crepe wadding in specific application is produced by the action of a doctor blade scraping the sheet from a Yankee dryer in well known manner and as illustrated, for example, in United States Patent 3,013,- 832, H. F. Donnelly, inventor. The crepe ratio is high, suitably about 3:1 and at least 2:1, and stretching and ironing of the sheet after crepe formation are specifically avoided in order to retain the crepe ratio high. The wadding basis Weight is dependent upon the application to which the final product is subjected but commonly is about 13# per 3,000 sq. ft. Such basis weight material holds the crepe well. The crepe cellulose wadding for most applications contains a wet strength material, usually a resin such as melamine formaldehyde, urea for-[nah dehyde, polyalkylamine-epichlorohydrin, polyamide-epichlorohydrin condensation products or a wet strength ma terial of less permanent nature such as dialdehyde starch. Wet strength treatments are common and are described in Tappi Monograph No. 13 entitled, Wet Strength in Paper and Paperboard.

The crepe tissue in single ply form 16 is passed from supply roll 15; the roll is preferably driven in the direc tion indicated by the arrow to minimize tension on the web as it is advanced toward a dip roll 18 in contact with an adhesive 19 in dip pan 20. The crepe tissue 16 is directed to roll 18 in such manner as to kiss contact the roll so that only the peaks of the tissue receive adhesive. Roll 18 is also driven and rotates in the direction indicated by the arrow. The adhesive application is maintained very light so that some peaks may not receive adhesive; this light application insures maintaining the valleys free of adhesive and much of the hills leading to the peaks free also. Such application is important in several respects; adhesive is conserved, the web is not altered materially by the adhesive application as to stiffness, absorbency, porosity or the like, and cost is maintained low. In general, the total adhesive on spaced peak areas will not cover more than about 10% to 25% of the tissue area. The roll 18 may be smooth but preferably has a lightly etched design overall which assists in maintaining a complete film of adhesive on the roll surface. To prevent excess adhesive passing to the web, a scraping blade 21 bearing against the roll 18 is provided.

In many modes of forming crepe tissue one side is more rough than the other and preferably the rougher side is presented to the adhesive applicator dip roll 18.

The adhesive should be water-insoluble for most product applications. Preferably, the adhesive is a plastisol but nonaqueous dispersions, solutions in organic solvents and the like may be employed. A conventional plastisol comprising 100 parts of polyvinyl chloride dispersed in about 60 parts by weight of diisodecyl phthalate and having a viscosity of about 3,000 centipoises Brookfiel-d as measured with a #4 spindle at rpm. is useful as the adhesive of dip pan 20. However, other polyvinyl resins, plasticized or unplasticized, such as polyvinyl acetate, and copolymers serve the purpose; also, the acrylic resins such as the alkyl acrylates, the butadiene resins such as lbutadiene-styrene and butadiene-acrylonitrile; the epoxy resins and the formaldehydes such as melamine formaldehyde; may be employed. The extent of penetration of the web material by the adhesive is dependent upon the adhesive system; for most applications, plastisols comprising vinyl chloride resins and/or vinyl chloride with other vinyl resins plasticized with the organic phthalates, sebacates or adipates are desirable as they penetrate only part Way into the hills of the crepe, and migration is limited.

The adhesive carrying crepe tissue is directed around roll 23. Closely adjacent the roll 23, as illustrated at 25, is

a draw frame from which the highly drafted unbonded striated web material 26 of rayon is directed to the adhesive-carrying side of the web. Only sufficient tension exists in the striated web material to maintain fiber alignment. This tension is very low and the web material is, in effect, simply wafted to and laid down upon the peaks of the crepe tissue. Since these peaks in a crepe tissue may be very closely spaced, about 40 to the inch, for example, when the crepe ratio is 2:1, the web material will be across the uppermost of the peaks and be well supported. Since the uppermost of the peaks will also have received the major portion of the adhesive, the web will be Well supported. The striated web, since it is formed of synthetic fibers 24 of a denier of between about 0.5 to 3 or more, will have little tendency to sag into the closely spaced valleys of the crepe tissue even though the fibers may pass across a plurality of hills without contacting adhesive. The individual strands of the web function, in fact, relative to the crepe tissue like rigid rods and there is no significant tendency to sag even when the peaks are spaced as close as 3 to the inch.

The striated web fibers, as described, are suitably of rayon and also, preferably, the web is as light and thin as possible consistent with the requirement of handling in drafting and through the draw frame to the tissue. Webs having a square yard weight of between about 3 to 20 grams have been drawn at speeds of from 20 to 500 feet per minute. In such operations the web fed to the tissue maintains in general the highly aligned condition of the fibers; some fiber grouping may be tolerated in view of the bulk of the final product. Commonly, however, or more of the fibers will be in aligned condition. Useful staple length fibers or'monofilamerits in the drafted drawn form useful in the products of this invention include: nylon, rayon, polyesters, acrylonitriles, polyamides, polypropylene and other synthetics. Important to the product is that the striated web material have low stretch, that is, 10% or less elongation at break. With such fibers present in sufficient number to cover the peaks carrying adhesive, preferably contiguous or nearly so, there will then be no tendency for isolated areas to lose their crepe characteristic upon wetting.

The vinyl chloride plastisol on the tissue 16 does not immediately bond to the striated web. For the purpose of attaining adequate bonding, the composite passes from the roll 23 to a large diameter drum 27 operated at a surface temperature of about 325 F. The drum rotates in the direction indicated by the arrow and the composite passes to the drum over guide roll 28. The highly drafted web is now at least frictionally held on the surface of the crepe tissue, covers the adhesive on the peaks, and may be adhesively retained if the adhesive is selected for this purpose. In any event the tension on the composite may be increased over that applied to the tissue alone at the adhesive application stage. The plastisol adhesive, softened by the heat, tends to flow around the fibers and to be set when cooled. The driven roll 29 is relatively soft, about 60 durometer, and presses the composite to the surface of drum 27. From the drum 27 and roll 29 the composite passes in the direction indicated by the arrows around guide rolls 30, 31 and is drawn around roll 32 to windup on driven spindle 33 carried by a bracket 34 pivoted at 35. Roll 32 is driven by friction contact wth the roll as it is wound up.

Two such composites are roll formed to make the product of FIG. 1. The composites are cross-laid by any of several arrangements, one type of suitable mechanism being illustrated in United States Patent 2,841,202. For this purpose, as illustrated in FIG. 4, one tissue-striated fiber composite 30 is passed longitudinally in the direction indicated by the arrow to the cross-layer 38. The cross-laying equipment 38 includes the belt 39 which follows a helical path, as described in the above-mentioned patent, the general belt traverse only being indicated in FIG. 4. The cross-laid composite is laid down and cut as the combination proceeds to the hot box 40. It is not necessary to add adhesive between the composites if a thermoplastic has been employed as described hereinbefore. The thermoplastic adhesive softens in the hot box 40, and the traveling material passes between calender rolls 41, 42. The pressure exerted need only be light to insure that the adhesive carried by the composites flows sufficiently to bond the inner cross-laid plies of striated web material together. From the calender rolls the product passes through a cooling zone designated at 43 and which may be simply a cold air blast directed to the sheet material. The sheet material thus formed is wound at 44 and is the product illustrated at 1 in FIGS. 1 and 2.

A finely creped tissue product, in accordance with the invention, is illustrated in FIG. 5 with portions of plies removed to more clearly illustrate component arrangement. Fine creping provides for uniformity in the tissue paper itself, as well as in the sheet product of the invention. The illustration of the surface in FIG. 5 is derived from a photomicrograph. The product has a hill and valley count of about 40 per inch of product length. For purposes of use in toweling, =washcloths, wipes and the like, the hill and valley count is preferably between about 25 to 50 per inch. It will be understood that this is a more critical criterion for many purposes than crepe ratio since the latter does not take into account the nature of the crepe, that is, whether it is fine or coarse.

In practice, the sheet material produced as described herein and having a crepe ratio of about 2:1 and a hill and valley count of about 40 per inch has been thoroughly soaked with water and dried. The crepe ratio and the count also were found to be substantially unaffected after drying; the count, in some cases, may decrease slightly if a very large number of the peaks are not bonded to the web. In contrast, similar sheet material lacking the restraining striated web loses its crepe completely when similarly wetted. Additionally, twsting and balling up of the sheet material in the Wet condition does not occasion any significant loss of crepe. Importantly also, the inclusion of the web material in the product does not have any noticeable effect in the absorbency of the tissues, probably because such a small amount of adhesive is necessary to attain the product.

The product, after immersion in clear and soapy water, shows no appreciable shrinkage or extension of dimens1ons.

Important to the process of producing a product of optimum properties is that the striated web material be wafted or floated onto the tissue. Such inhibits collapse of the crepe and is more important where the crepe is more coarse for, in such tissue, the tendency of the peaks to be depressed is greater.

Certain rearrangements of the layer structure and layer elimination also are possible for specific applications. Thus, as illustrated in FIG. 6, the striated web may form one outer surface 50 with the crepe tissue forming one outer ply 51 and an inner oppositely disposed ply 52, the second striated web 53 forming the restraining element for tissue 51. In this instance the ply 50 is relatively smooth to the touch, and the absorbency of the product is unimpaired. Where less absorbency is required, the combination of only a highly creped tissue layer and a restraning striated web is effective, one surface in the instance being relatively rough (the crepe surface) and the other relatively smooth (the fiber layer).

The basis weight of sheet material produced in accordance with the invention may vary widely and is primarily dependent upon the basis weights of the crepe tissue layers. For specific purposes these, of course, need not be the same. Sheet material (FIG. 1) formed with crepe tissues having a basis weight of about 13# per 3,000 sq. ft. and rayon of a denier of 1.5 will have in the finished product a basis weight of about 59 pounds. Preferably a for toweling, washcloth and wipe use, the basis weight of the product will be in the range of 25 to about 75 pounds. For such purposes the crepe tissue ply may have a basis weight of from about 4 pounds to 20 pounds. Additionally, for some uses the crepe ratio may be somewhat lower, that is, about 1.5, particularly when the count per inch is high, but, in general, higher crepe ratios are preferred.

To attain the desired basis weight the structure may include more or less plies of crepe tissue and for this purpose the crepe tissue may be bonded to itself initially before striated web application and the crepe ratio of each ply may be different.

For the purpose of attaining further bulk and improving product appearance and feel, the sheet material of the invention may be cold calendered, embossed or both. Suitably, the material is random dot embossed to soften the product as indicated at 48 in FIG. 5 and is heat embossed as at 49 to provide an even more rugose surface.

The product has been specifically described in connection with crepe cellulosic webs which are creped only transversely to the longitudinal direction of the creped sheet itself. In some instances a crepe sheet may be so creped that a single sheet is extensible in all directions. The four ply product described is materially effective in retaining crepe in such webs also.

The product is generally characterized by bulk, flexibility, soft hand and feel when wet and dry, strength, resistance to puncture, good ply adhesion particularly when wet, wet rub resistance, high absorbency, excellent toughness wet and dry, drapes well and is reusable in toweling and wipe applications many times. The material may itself be washed clean, thus making it very suitable for wipe applications. The valleys of the crepe are so formed that they constitute not only zones for fluid retention, including water and oil, but the valleys serve as dead air spaces to provide heat insulation characteristics. Additionally, there is some yield in the product in the bias direction, that is, at an angle of about 45 to the web material directions, a factor which probably contributes to the toughness and workability when wet.

What is claimed is:

1. A sheet material crepe tissue product having a capacity for the retention of fluids and exhibiting a toughness which permits manual working of the product without significant loss of physical characteristics including fluid retaining capacity, said tissue product comprising self-sustaining but extensible cellulosic crepe tissues forming outer plies of the product and having hills and valleys including rows of closely spaced peaks defining the crepe structure and providing for bulk and absorbency in the tissues, adhesive on peaks on one side of the tissues, and cross-laid layers of striated web material of relatively inextensible synthetic fibers lying in generally aligned relation forming inner plies of the product, each said crepe tissue ply being bonded at tissue peaks to striated web material so that the aligned fibers of said striated Web bridge rows of adhesive-carrying peaks of the tissue without substantial sag into the valleys of the tissue and each tissue ply being creped substantially perpendicularly with respect to the striation direction of the web material to which it is adhered and substantially perpendicularly also to the crepe direction of the tissue bonded to the other layer of striated -web material.

2. A sheet material tissue product as claimed in claim 1 and in which the synthetic fibers have a denier in the range of about 1.5 to 3.

3. A sheet material crepe tissue product as claimed in claim 1 and in which adhesive on the peaks of the crepe bonds the crepe to the striated web material and extends to and bonds the layers of striated web material together also.

4. A sheet material crepe tissue product as claimed in claim 1 and in which the crepe tissue has a basis weight of between about 4 to 20 pounds per 3,000 sq. ft. and the 7 8 product has a 'basis Weight of between about 25 and 75 2,653,870 9/1953 Kast 241162 pounds per 3,000 sq. ft. 2,996,424 8/1961 Voightrnan et a1. 162-112 JACOB H. STEINBERG, Primary Examiner.

5 I. D. FOSTER, Assistant Examiner.

1,870,215 8/1932 Anderson 161-129 2,014,460 9/1935 Alm 161148 2,314,876 5/1943 Greene 161129 16159,129,136;162-112;15-209 References Cited UNITED STATES PATENTS

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