US 3291678 A
Description (OCR text may contain errors)
Dec. 13, 1966 K M. ENLOE ETAL METHOD OF COMPRfiJSSING CREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 12 Sheets-Sheet l Dec. 13, 1966 K. M. ENLOE ETAL 3,291,678
METHOD OF COM 35 CREPED PAP TISSUE STACKS AT CI MOISTURE C ENT Original Filed May 9, 1961 12 Sheets-Sheet 2 Dec. 13, 1966 ENLOE ETAL 3,291,67
METHOD OF COMPRESSING CREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 v 12 Sheets-Sheet 3 Dec. 13, 1966 K. M. ENLOE ETAL 3,291,?
METHOD OF COMPRESSING GREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 12 Sheets-Sheet 4 3, 1956 K. M. ENLOE ETAL 3,291,678
METHOD OF COMPRESSING CREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 12 Sheets-Sheet 5 Dec. 13, 1966 K. M. ENLOE ETAL 2 METHOD OF COMPRESSING CREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 12 Sheets-Sheet 6 Dec. 13, 1966 ENLQE E L 3,291,678
METHOD OF COMPRESSING CREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 12 Sheets-Sheet 7 3, 1966 K. M. ENLOE ETAL METHOD OF COMPRESSING CREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 12 Sheets-Sheet 8 Dec. 13, 1966 K. M. ENLOE ETAL 3,291,678
METHOD OF COMPRESSING CREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 12 Sheets-Sheet 9 i l l 12 Sheets-Sheet 1O ENLOE ETAL METHOD OF COMPRESSING CREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 Dec. 13, 1966 @Q QQ Ru kmm bukk q Dec. 13, 1966 K. M. ENLOE ETAL 3,291,678
METHOD OF COMPRESSING CREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 12 Sheets-Sheet 11 QQv QQQ
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METHOD OF COMPRESSING CREPED PAPER TISSUE STACKS AT SPECIFIC MOISTURE CONTENT Original Filed May 9, 1961 l2 Sheets-Sheet 12 United States Patet 3,291,678 I METHOD ()FCQMPRESSlN-G CREPED PAPER TIS- SUE STACKS AT SPECEFIC MOISTURE CONTENT Kenneth M. Enloe and Le Roy L. Peterson, Neenah, Wis.,
assignors to Kimberly-(Dinah Corporation, Neenah, Wis., a corporation of Delaware Original application lvlay 9, 1961, Ser. No. 111,417, now Patent No. 3,172,564, dated Mar. 9, 1965. Divided and this application May 15, 1964, Ser. No. 367,810 4 Claims. (Cl. 162113) This application constitutes a division of our copending application, Serial No. 111,417, filed May 9, 1961, now Patent No. 3,172,564, for Manufacture of Cellulosic Products, which in turn, is a continuation-in-part of our application Serial No. 19,981, filed April 22, 1960, for Cellulosic Product and Method for Making Same (now abandoned).
The invention relates to paper tissues, particularly of the type-suitable for facial usage, and to methods for making, converting and packing such tissues.
Facial tissues comprising creped paper sheets of a basis weight (uncreped) of about 6 to 10 pounds per ream (2,880 square feet) and usually of two-ply construction have in recent years come into Widespread usage. Ordinarily, the tissues are boxed in a paperboard dispensing carton, and the tissues are folded in some manner Within the carton. In one well known form, the tissues are interfolded, so that each tissue when it is dispensed from the carton automatically brings the next successive tissue into easily accessible position.
Due to certain conditions, such as air entrapment between the tissues, lack of sharpness of the folds of the tissues, and the creped texture of the tissues with fibrous peaks of tissue being relatively upraised to give the tissues an apparent thickness greater than the actual tissue thickness, clips or stack of the tissues are quite space consuming. These conditions, particularly the amount of air entrapped and the sharpness of the folds, may also vary somewhat so that the tissue clips vary substantially in height; and thus it is necessary that the height of the cartons be sufficient to allow for such variability. A clip of 350 plies or 175 two-ply tissues, for example, would for these reasons require a relatively high carton of 3% inches in height, and a clip of 400 plies or 200 two-ply tissues would require a carton about 4 inches in height. Aged clips of 400 plies in uncompressed condition have heights of 3 inches to 4 /2 inches, and the densities of the uncompressed tissues range from 1.75 grams per cubic inch to 2.63 grams per cubic inch.
It has previously been proposed to compress clips of tissues so that the clips are not only more uniform in hei ht but are substantially lower in height than prior clips of uncompressed tissues, and it has also been noted that such compression improves the quality of the end product. The compression that has been found necessary varies with the moisture content of the tissues, a greater pressure being required for lower moisture content and vice versa, for obtaining substantially uniform heights. Such proposals have been made in a prior application of Kenneth J. Harwood, Serial No. 729,578, filed April 21, 1958 (now abandoned). The subject matter of the latter application has been included in a continuation-in-part application, Serial No. 110,612, filed May 9, 1961 now Patent No. 3,172,563, a division of which was filed on May 15, 1964, Serial No. 367,809 and now abandoned (all three applications being commonly owned).
In the latter Harwood application, more specifically it was proposed that stacks of tissues be compressed approximately to 12% to 29% of the original stack height. For tissues having about 6% moisture, 750 pounds per square inch pressure was proposed; while if the tissue moistures too were approximately 4% and 10%, pressures of 1,400 pounds per square inch and 240 pounds per square inch respectively were suggested.
Compression with such pressures has been found to yield permanently reduced height stacks of tissue; however, we have found that the quality of the end product may be increased still further if lower pressures are utilized. It is, therefore, an object of the present invention to provide an improved method for compressing stacks of facial tissues yielding a higher quality product, particularly utilizing smaller compression pressures than previously proposed. Pressures ranging from approximately 15 pounds per square inch to 900 pounds per square inch have been found appropriate for stacks of tissues having a moisture content of 5 /z%, yielding stacks that are permanently reduced in height a substantial amount and with tissues having a very high quality, particularly insofar as smoothness, softness and limpness are concerned.
Tissues of facial grade may be manufactured by creping the tissue from a drier drum of a papermaking machine and then calendering and stretching the tissue to remove again most of the creping, so as to provide a desirably soft, smooth and limp tissue. The tissue may be stored after calendering in the form of so-called hard rolls prior to its being folded by folding machines. The moisture content of the tissue, when the compressing operation is used, is somewhat critical; and We have found that if the moisture content of the tissue in the hard rolls is too high or too low, the hard rolls on their exterior surfaces either lose moisture or else gain moisture with storage. Such lack of uniformity leads to non-uniformity and spoilage of some of the end product. If there is an increase of moisture in the tissue, the tissue on compression between compression members of fixed spacing becomes relatively stiff and papery; and, on the other hand, if moisture is lost, the tissue is not compressed to its desired small clip height. Thus individual hard rolls that vary in moisture content can not be run on a compressor the adjustment of which remains the same. Also, too great a moisture content in the tissue when it is stored in hard roll form results in compression of the tissue by itself in the rolls, the tissue becoming relatively hard and stiff, particularly at the center of the roll.
It is, therefore, an object of the invention to provide hard rolls for facial tissue that is to be compressed, which rolls have such a moisture content that no substantial gain or loss of moisture occurs from the rolls at ordinary atmospheric humidities. Such moisture content has been found to be about 5 percent as a compromise value.
We have also found that if the calendering and stretching above referred to are practiced on tissue having this 5 /2 percent moisture content, the moisture content has proved to be too high for successful calendering and unnecessary stilfness and paperiness of the tissue results.
It is therefore another object of the invention to provide an improved method for making compressed folded facial tissues which includes the use of tissue having a relatively low moisture content in the calendering and stretching stages and subsequently adding moisture to the tissue, so that the hard rolls have a relatively high moisture content at which there is little gain or loss of moisture of the tissue in hard roll form.
Interfolded tissues for easy dispensing from a carton generally have been provided with tissue bonds between adjacent tissues for aiding in the dispensing and assuring that succeeding sheets are partially pulled out of the cartons for easy accessibility, due to the particular mode of interfolding practiced such as is shown in the patent to Reinhardt N. Sabee, No. 2,626,145, issued January 20,1953. Interfolding may also be practiced by longitudinally interfolding tissue webs which, however, does not provide such bonds.
It is another object of the present invention to provide interfacial bonding between adjacent sheets for use particularly with such longitudinal interfolding methods, as by compressing clips of the tissue, so that the tissues so interfolded without such bonds may nevertheless have sufiicient attachment to each other that the tissues are automatically dispensed from the cartons.
The invention consists of the novel constructions, ar-
rangements, devices and methods to be hereinafter described and claimed for carrying out the above stated objects, and such other objects, as will be apparent from the following description of preferred methods and apparatus for practicing the invention and which are illustrated in the accompanying drawings, wherein:
FIG. 1 is a side elevational view of the terminal end of a paper tissue making machine;
FIG. 2 is a view similar to FIG. 1 but on a smaller scale and in diagrammatic form and also showing a soft roll into which the paper is wound from the paper machine;
FIG. 3 is a diagrammatic elevational View of a rewinder or calender effective on paper drawn from soft tolls;
FIG. 4 is a top view of a portion of a paper interfolder;
FIG. 5 is a perspective view of fragmentary portions of the interfolder;
FIG. 6 is a cross sectional view of a stack of paper tissues as interfolded by the interfolder illustrated in FIGS. 4 and 5;
FIG. 7 is a perspective view of a compressing machine for compressing clips of the tissues as so interfolded;
FIG. 8 is a perspective view of a carton partially broken away to show a clip of the interfolded tissues packed therein;
FIG. 9 is a side elevational view of cutting mechanism for cutting the interfolded tissue into clips;
FIG. 10 is a perspective view of mechanism for adding moisture to the tissue as it passes through the rewinder;
FIG. 11 is a diagrammatic illustration of a moisture sensing head which is a part of the mechanism illustrated in FIG. 10;
FIG. 12 is a diagrammatic illustration of a part of the mechanism illustrated in FIG. 10;
FIG. 13 is a fragmentary sectional view of a portion of the mechanism illustrated in FIG. 12.
FIG. 14 is a graph showing the relationship between the pressure (P) in pounds per square inch applied on to a ZOO-ply stack of facial tissues and the gap (G) in inches between the members performing the compression on the tissue stack;
FIG. 15 is a graph similar to that of FIG. 14 for very small pressures of compression;
FIG. 16 is a graph showing the relationship of tissue stifiness (S) and the gap (G) in inches between the compressing members;
FIG. 17 is a graph showing the relationship of the bulk (B) in inches of ZOO-ply stacks of tissues with different gaps (G) in inches between the compressing members for various tissue moisture levels;
FIG. 18 is a graph showing the variation of bulk (VB) in inches of ZOO-ply tissue stacks with the gap (G) at which compression of the tissue stacks takes place;
FIG. 19 is a graph showing the pressures for compressing the tissues that shall preferably be used for securing a substantial reduction in bulk without undue tissue stiffness.
FIGS. 20A and 20B are respectively perspective views of cartons with noncompressed and compressed tissues therein, the views being disposed side by side so as to illustrate the difference in height of the cartons using these two types of tissues;
FIG. 21 is'an elevational view of C-folded tissues with which the invention may be practiced; and
FIG. 22 is a perspective view of a carton packed with C-folded tissues which have previously been compressed in accordance with the teachings of the invention.
Like characters of reference designate like parts in the several views.
The invention is concerned with facial tissues of the general type previously mentioned herein, the sheet of which have a basis weight of about 6 to 10 pounds per ream of 2880 square feet (drier basis weight uncreped). More particularly, it is contemplated that the basis Weight may be about 7.6 pounds per ream. Each tissue preferably comprises two plies of such paper sheets; and the tissues are folded, such as by interfolding. The furnish used for the paper is bleached by conventional processes so as to remove any coloring material as well as other impurities usually removed by such bleaching processes. In addition, no sizing is added to the furnish so that the tissues are quite absorbent, particularly in view of the light basis weight of the paper. The paper is dry creped from the drier drum of the papermaking machine and the paper is calendered as will be more specifically described for working the paper fibers and surface for giving a soft, smooth and limp paper particularly suitable for facial usage.
Referring now to the drawings, the paper converting apparatus as illustrated includes a conventional Fourdrinier type papermaking machine having a so-called Yankee drier drum 10 at the terminal end of the machine. A supporting frame 11 is provided for the drum 10. A shaft 12 extends through the drum, and the drum is rotatably supported by means of bearings 13 for the shaft 12 which are secured to the frame 11. The drum 1% is rotated by a conventionaldrive mechanism, such as a motor 14, which is drivingly connected to the shaft 12. A heating hood 15 is secured to the frame 11 and extends around the upper portion of the drum 1G. Suitable hot air inlets and outlets are provided in the hood for the entry and discharge of the air or other heating medium applied to the hood.
The wet paper web to be dried is carried by a felt web 16 which travels around felt rolls 17. The paper web is forced against the surface of the drum It) by a pressure roller 18 which is rotatably mounted in brackets 19 secured to an arm 20. The arm is pivoted to the frame 11, and the pressure roller 18 is forced against the surface of the drum 10 by a hydraulic piston and cylinder assembly 21 that acts against the arm 20.
The paper web W is removed from the surface of the drum 10 by a doctor blade 22 which is held in contact with the surface of the drum 10 by any suitable mounting mechanism. The web W of creped wadding from the drum 10 is wound into a so-called soft rol 24 formed on a mandrel 25 which is rotatably supported on a standard 26. The mandrel 25 is driven by any suitable driving mechanism, such as a motor 27.
In converting of tissues for cleansing or facial purposes, a so-called rewinder 28 is utilized. The tissues are preferably made of two plies of the creped tissue stock; and therefore, to provide a two-ply web, two rolls- 24 are rotatably mounted in the rewinder to permit withdrawal of the respective webs, with one web being superpositioned on the other. The rewinder includes sets of calender rolls 29, 30 and 31, idler rolls 32, and a pair of rolls 33 and 34 adapted to contact a so-called hard roll 35 of the web W which has passed through the rewinder.
The soft rolls 24 are each driven from a suitable prime mover, such as an electric motor 36; and each of the rolls 29, 30 and 31 are respectively driven from other prime movers, such as electric motors 37, 38 and 39. The roll 33 is driven by a prime mover, such as an electric motor 40. t
A system 41 for adding moisture to the web W subsequent to its travel between the calender rolls 31 is provided. The system 41 includes a housing 42 for a rotary brush 43 and having a slot 44 in its upper surface beneath the web W. The brush 43 is driven at a contant speed by any suitable driving mechanism, such as an electric motor 45. A water pick-up roll 46 is so positioned in the housing 42 that the bristles of the rotary brush 43 have a running clearance with the roll 46. A water trough 47 is disposed beneath the roll 46. Water is maintained in the trough 47 at a predetermined level by means of any suitable water supply and level controlling mechanism (not shown), the water level being such that the roll 46 has its lower peripheral surface in the pool of water in the trough.
The roll 46 is driven from one of the rolls 31 through a variable speed drive mechanism 48. The drive mechanism 48 may be of any suitable type and may comprise a drive pulley 49, a driven pulley 50, and a belt 51 extending around the pulleys 49 and 50. Both of the pulleys 49 and 50 are formed of opposite, separable, tapered pulley parts 52 and 53; and the belt 51 is of the V type so that its sides match the taper of the parts 52 and 53. The parts 52 are movable axially in unison by means of a lever 54 pivoted at 55, so that one of the parts 52 moves in one direction while the other moves in the opposite direction.
The pulley 49 is mounted on a shaft 56 and the pulley 59 is mounted on a shaft 57. Pulleys 58 and 59, respectively mounted for rotation with the calender roll 31 and the shaft 56, together with a belt 60, provide a driving connection to the pulley 49 from the roll 31; and pulleys 61 and 62, respectively fixed with respect to the shaft 57 and the roll 46, together with a belt63, provide a driving connection from the pulley 50 to the roll 46.
The lever 54 is actuated by means of an air pressure responsive motor 64 comprising a piston 65 reciprocable in a cylinder 66. A spring 67 is disposed between one end of the cylinder 66 and the piston 65.
The variable speed drive mechanism 48 is controlled by a capacitance responsive head 68 that is positioned in contact with the paper web W between the rolls 31 and the adjacent roll 32, subsequent to passage of the web beyond the housing 42. The head 68 comprises a plurality of opposite spaced plates 69 and 70 constituting a condenser 71, with the web W between the plates of the condenser constituting the dielectric. As will be understood, the capacity between the plates 69 and 70 increases with increases in the moisture in the paper web W between the plates 69 and 79. One of the plates 69 is grounded, and the other plate 70 is connected to the inlet end of an amplifier '72. Another condenser 73, which may be termed a reference condenser, is also connected to the inlet end of the amplifier 72. A motor 74 having an armature 75, an energizing winding 76 and a control Winding 77 has its winding 77 connected to the output end of the amplifier 72. The armature 75 is connected by shafting 78 with the variable element of the condenser 73, and the arrangement of the motor 74 and the amplifier 72 is such that the armature 75 is rotated in one direction or the other so as to move the variable element of the condenser 73 in such a direction and with such a degree of movement that the capacity of the condenser 73 corresponds with the capacity of the condenser 71. The position of the movable element of the condenser 73 thus corresponds to .and is indicative of the capacity of the condenser 71 and thus the degree of moisture that exists in the web W.
The motor 74 is connected to a pneumatic controller 79 which functions to change the air pressure in a conduit 80 connected to the cylinder 66, so as to change the speed ratio through the mechanism 48 in accordance with changes in web moisture. The pneumatic controller 79 comprises a cam 81 that is drivingly connected with the shafting 78 of the motor 74. A follower arm 82 rides on the cam 81 and is adapted to control the air discharged from -a nozzle 83 in the end of an air conduit 84 which is connected to a source of air pressure 85. The conduit 84 has a restriction 86 in it, and the conduit 80 is connected to the conduit 84 between the restriction 86 and the nozzle 83. A bellows 87 is connected at one end to the conduit and is fixed from axial movement on this end. The other end of the bellows is fixed to an arm 88 that is pivoted at 89, and a compression spring 9% acts on the arm 88 oppositely to the bellows. The conduits 84 and 80 are flexible in the portions so in dicated, so as to allow the nozzle 83 to move along with the arm 82 as it follows the cam 81.
Light responsive mechanism is used to detect breaks in the web W for automatically reducing the speed of the roll 46 when such breaks occur. This mechanism comprises a photo-cell 91 positioned beneath the web W and an opposite light source 92 positioned above the web W. The photo-cell 91 is connected by means of a conventional amplifier 93 with an electro-magnet 94 that is effective on a valve 95. The valve 95 comprises a piston 96 having a circumferential groove 97 therein which is so disposed that, when the electro-magnet 94 is de-en ergized, the valve 95 completes the conduit 80. The valve 95 is connected to a source of air pressure 98; and the valve is so arranged that, when the electro-magnet 94 is energized, the source of air pressure 915 is connected to the motor 64 through a portion of the conduit 80.
The tissue, subsequent to being calendered in the rewinder 28, is folded by any suitable mechanism, such as, for example, the interfolding mechanism shown in a copen ding application of Harold V. Rutkus and Charles J. Greiner, Serial No. 837,977, filed September 3, 1959 (now Patent No. 3,066,932, issued December 4, 1962). Basically, referring to FIG. 4, this mechanism may comprise a plurality of left-hand folding boards 99 and a plurality of right-hand folding boards 100. The folding boards 99 and 11113 are alternately arranged with a righthand folding board following a left-hand folding board and vice versa. The hard rolls 35 from the rewinder 28 are cut into segments by any suitable mechanism, and the segmented hard rolls 101 are mounted on opposite sides of the folding boards 99 and 109 by means of standards 192. The web W from the segmented hard rolls 101 extends over an obliquely extending folding bar 103 for each of the left-hand folding boards and over an oppositely extending folding bar 104 for each of the right-hand folding boards. The web W then extends over a bar 165 at the head end of each of the boards 99 and and underneath the boards which folds the webs so the folded webs travel in a path 196.
Each of the right-hand folding boards 191) has an inclined plane portion 197 extending transversely of the path 106, an inclined plane portion 108 extending parallel with the path 106, and a horizontal plane portion 109 overlying the path 106. The portion 1119 is defined by a straight edge 110 extending obliquely across the path 106. The left-hand folding boards 99 have parts 197a, 108a, 109a and 110:: corresponding to the parts 197, 198, 199 and 110 respectively of the boards 1%; but, as is apparent from the drawings, the left-hand folding boards are formed oppositely, with the parts 1118a being opposite to the parts 168 with respect to the path of travel 106.
A cutting mechanism 111 of any suitable type is provided for cutting the tissue as folded by the boards 99 and 109. The mechanism 111, as illustrated, comprises a plurality of pressure feet 112 carried by a wheel 113. A cutter knife 114 is disposed on one side of each of the pressure feet and is actuated by any suitable mechanism causing it to have a slicing action along side of the respective pressure foot, so that the folded tissue is cut into clips 115 of predetermined length as the wheel 113 rotates and the knives have their slicing action. A belt 116 supported by rollers 117 and a second belt 118 supported by an elongated shoe 119 are positioned respectively above and below the clips 115.
The clips 115 may be compressed by any suitable mechanism, such as by the mechanism disclosed in the copending application of Charles J. Greiner and Anthony S. Hubin, Serial No. 731,061, filed April 25, 1958 (now Patent No. 2,960,023, issued November 15, 1960). Such a compressing mechanism, in brief,'may comprise a plurality of platens 120 and 121 carried on upper and lower articulated chains 122 and 123. The chain 122 extends around opposite sprockets 124 and 125, and the chain 123 extends around opposite sprockets 126 and 127. The sprockets are driven in timed relationship to each other by any suitable mechanism (not shown) so that the platens 120 and 121 move along with and individually vertically disposed with respect to each other.
A cam 128 is provided for the upper chain 122 and a cam 129 is provided for the lower chain 123. The cams 128 and 129 are so arranged that the platens 120 and 121 are moved toward each other as they pass between the cams. A plurality of buckets 130 are provided for holding the clips 115 of tissue, and buckets are positioned at one side of the platens 120 and 121 on a suitable conveyor (not shown) so that the clips may he slid from the buckets between opposite pairs of the platens 120 and 121.
In operation, the Fourdrinier papermaking machine functions in the well known manner, carrying the Web W on the felt 16 that passes over the rolls 17 and 18. The web W is transferred at the roll 18 onto the drum 10 and the web W is then doctored off the drum 10 by the blade 22 and is wound onto the mandrel 25 for forming the soft roll 24.
Steam under pressure is applied to the drier drum 10 for heating the drum so as to partially dry the web W as it passes around the drum. The speed of the papermaking machine and the temperature of the drum 10 are so controlled that a predetermined amount of moisture remains in the web W as it leaves the drum at the blade 22. Preferably, the web W shall have a moisture content of less than percent, and the moisture content shall desirably be in the range of 3 to 5 percent, as the web is doctored off the drum 10. The moisture in the web W may be determined by conventional measuring methods, such as by weighing the web prior to complete voiding of moisture from the web, as by heating, and subsequent to such evacuation. It will be understood that the moisture content may be decreased by increasing the temperature of the drum and/or decreasing the speed of the papermaking machine, while an increase in moisture content may be obtained by decreasing the temperature of the drum 10 and/ or increasing the speed of the machine. The blade 22, as with conventional operation, crepes the web W to a certain extent as the web is doctored off the drum 10, and the creping may be on the order of 120 percent, that is, the web is decreased in length by the action of the blade 22 to less than half its length when in position on the drum 10. For this degree of creping, the web W has a crepe ratio of 2.2, the crepe ratio being the length on the drier divided by the final length. In this case, one foot of web on the drier has been longitudinally compressed to 5 /2 inches, so that the crepe ratio is 2.2. The doctor blade 22 in its action crinkles the web in creping it, producing peaks and valleys in the web, with the peaks being relatively sharp and high compared to the thickness of the web. The web W from the papermaking machine is wound onto the mandrel to form the soft roll 24 for subsequent use in the rewinder 28.
The rewinder 28 may be used either with one or more of the rolls 24 simultaneously. If two plies are desired in the finished tissue, two of the rolls 24 are used as is illustrated. Web W is drawn from each of the rolls 24 and is passed consecutively between the rolls 29, 30 and 31 and is finally wound into a so-called hard roll 35. The pairs of rolls 29, 30 and 31 have a pressure nip between them so as to compress and calender the web as it passes between the rolls. various rolls in the rewinder 28, which are connected to the. motors 36 to 40, are so driven thereby that the web Furthermore, the
is stretched as it passes through the rewinder, the total stretch being preferably such as to decrease creping from the 2.2 ratio previously mentioned to about 1.2 ratio. For the web having a length on the drier of one foot and shortened by creping to a length of 5% inches, the rewinder stretches the web back to a length of 10 inches, so that its crepe ratio is now 1.2 (1 foot drier length divided by 10 inches final length), and this ratio may well vary in the range of 1.05 to 1.30 within the teachings of this invention. The web has thus been again stretched, practically back into its original length. The restretching of the web by the rewinder and the calendering action by the rolls 29, 30 and 31, acting with pressure on the web as it passes between the rolls, have the effect of rendering the tissue quite soft and limp, so that the tissue has these desirable qualities for use as a facial tissue. Incidentally, practically all of the stretching, about percent of it, in such a rewinder 28 is preferably done between the soft rolls 24 and the first press rolls 29, and the subsequent press rolls 30' and 31 function principally as calender rolls so that the web not only is soft and limp but, in addition, has a smooth surface.
The system 41 functions to add moisture to the web W subsequent to the calendering action of the rolls 31 and prior to the winding of the web into a hard roll 35. The brush 43 is driven at a constant speed by the motor 45, and the brush 43 makes contact on the bristle ends with the roll 46 that functions as a metering roll. Water is maintained at a constant level in the trough 47 with the roll 46 dipping into the pool of water, and the brush 43 in contacting the roll 46 picks up water from the surface of the roll 46 and throw it through the slot 44 in the housing 42 onto the web W. The speed of rotation of the roll 46 is varied in order to vary the amount of water picked up by the roll 46 from the trough 47 and transferred onto the brush 43, thus to vary the rate at which water is thrown by the brush 43 through the slot 44 onto the web W and to vary the increase of moisture thus provided in the web W by the system 41.
The capacitance head 68 functions as a sensing unit to increase the speed of rotation of the roll 46 if the web W is too dry, thereby increasing the moisture applied to the web to bring its moisture up to the predetermined desired value, and functions oppositely to reduce the speed of rotation of the roll 46 for decreasing the amount of water applied to the web W when the moisture content in the web W is too high.
The head 68, as above described, includes opposite plates 69 and 70; and, if there is too little moisture in the web W, the capacity between the plates is unduly low. The amplifier 72 so functions, if the capacity of the condenser 71 is too low, to correspondingly'decrease the capacity of the condenser 73 by correspondingly rotating the armature 75 of the motor 74. The rotative position of the movable part of the condenser 73 is, incidentally, indicative of the relative moisture that exists in the web W. The armature 75, in rotating, turns the cam 81 drivingly connected to it correspondingly and opens the nozzle 83 to a greater extent, due to the movement of the lever 82 following the cam 81. Air under pressure is supplied to the conduit 84; and, when the nozzle 83 is thus opened to a greater extent, the air pressure in the conduit 84 between the restriction 86 and the nozzle 83 is reduced. The air under pressure in the conduit 80 connected to this portion of the conduit 84 is applied onto the piston 65 in the cylinder 66 for changing the action of the speed changing unit 48, and this reduction of air pressure in the conduit 80 allows the spring 67 to be effective to move the piston 65 to the left as seen in FIG. 12.
The bellows 87, which is under the air pressure in the conduit 80, is under these condition less etfective in its action counter-balancing the spring 90, so that the spring 90 returns the nozzle in close proximity to the follower 9 82, with the nozzle 83 and bellows moving about the pivot 89. Equilibrium is thus again effected between the force on the lever 88 due to the spring 90 and the force on the lever due to the bellows 87, maintaining the pressure in the conduit 80 at a certain predetermined lower value corresponding to the rotation of the cam 81.
The solenoid 94 is assumed to be de-energized under the conditions just described, and the conduit 80 is thus complete between the nozzle 83 and the piston 65. The reduction in air pressure in the conduit 80 causes the spring 67 to be effective to move the piston 65 and lever 54 and to move the movable pulley parts 52 in opposite directions to decrease the effective diameter of the pulley 50 and increase the effective diameter of the pulley 49. Assuming that the speeds of the rolls 31 and thus the pulleys 58 and 59 and the drive shaft 56 remain without change; the speeds of the shaft 57, the pulleys 61 and 62, and the roll 46 are thus increased. The roll 46 thus draws more water from the pond within the trough 47, and the brush 43 removes this increased amount of water from roll 46 and throws it onto the web W so as to increase the moisture in the web W. Thus, the capacitance sensing head 69, in sensing a decreased amount of moisture in the web W, is effective to control the speed of the roll 46 through the connecting electrical and pneumatic systems so as to increase the moisture in the web W to make up the deficiency in moisture and return it to a predetermined value.
Conversely, if the moisture in the web W is too great, the parts of the capacitance sensing head 68 and the electrical and pneumatic control systems controlled by the head 68 function oppositely to reduce the speed of the roll 46 and thereby reduce the amount of water thrown onto the web W by the brush 43 so as to decrease the moisture within the web W to its desired predetermined value.
The function of the photo-cell 91 is to cause a reduction in speed of the water pickup roll 46 if a break in the web W should occur, so that an unduly great amount of water is not thrown off by the brush 43 under these conditions. If the web W breaks, the photo-cell 91 is energized, and it is effective through the amplifier 93 to energize the solenoid 94. The solenoid 94, when energized, moves the valve piston 96 so as to connect the source of air pressure 98 with the motor 64 through a part of the conduit 80. The air pressure is thus increased on the piston 65 and moves the piston 65 against the action of the spring 67 so as to increase the effective diameter of the pulley 50 and decrease the effective diameter of the pulley 49. The change speed unit 48 is thus effective to reduce the speed of the roll 46 under these conditions.
The electrical and pneumatic portions of the moisture adding system 41 are preferably so set that the brush 43 sprays just sufiicient water through the slot 44 to raise the moisture content of the web W as close to /2% as possible with the range of 5 /:%:L-1%, particularly. As will be subsequently pointed out, however, more or less moisture may also be used, if desired, to obtain satisfactory quality compressed tissues. For example, the web W may be maintained at a 4% moisture level by disabling the moisture adding mechanism 41, in which case, the increased pressures hereinafter mentioned may be utilized in using the compressor shown in FIG. 7 to obtain satisfactory tissues. The moisture in the web W may also be increased to much higher levels, as by means of the mechanism 41, in which case the hard rolls 35 are immediately used without storage and the pressures necessary for obtaining tissue stacks compressed to a certain reduced height are less.
We have found that if the creped wadding is run through the rewinder 28 with a moisture content greater than 5 percent, the web is squeezed out, stiffened and flattened due to the calendering action of the rolls 29, 30 and 31. Some of this stiffening action may be due to the fact that undue moisture content of the wadding in and of itself tends to unduly release the creping of the web. Sufiicient tension must be maintained on the web in order to obtain a uniform hard roll 35, and this tension also is effective to pull out the creping at high moisture levels of the web W. The desirable softness of the wadding is thus not obtained and the tissue is not fully satisfactory for facial uses when the web is run through the rewinder at high moisture levels. On the other hand, if the wadding is maintained at a relatively low moisture content of less than 5% as it is run through the calender rolls 29, 30 and 31, the wadding is not permanently compressed and stiffened, and the rewinder functions as intended, namely to smooth the tissue and render it soft and limp.
It is quite often necessary to store the hard rolls 35 prior to usage of them in folding the tissues. We have found that, if the hard rolls 35 have a moisture content of about 5 /2%; at ordinary humidities, the hard rolls do not increase in moisture content nor decrease in moisture content materially. At this moisture content, the wadding is at equilibrium with the atmosphere at the usual humidities at which the hard rolls are stored and the finished tissues are used. It is desirable that the hard rolls remain uniform as to moisture content due to the differences of action of later steps to be taken caused by non-uniformities of moisture content. When the tissue is stored as a hard roll 35, it is preferable that the hard roll have a moisture content less than 7.5 percent, since the tissue tends to compress itself in a hard roll, particularly at the core, and when so compressed, the tissue hardens and stiffens. Furthermore, at higher moisture content, some of the crepe is pulled out of the tissue when it is wound as a hard roll.
The hard rolls 35, which preferably have the 5 /2 percent moisture content, are cut into segments by any suitable mechanism and are then mounted on the standards 102 of the interfolding mechanism. Web W passes off of one of the rolls 101, over folding bars 103 and 105, and under a left-hand folding board 99. The bars 103 and 105 simply function to change the direction of motion of the Web, as is apparent. The web, in passing under the board 99, has one half or .fold 101a of it passing under the plane portion 107a; and the other half or fold 101b of it passes under the plane portion 108a, under the horizontal portion 109a and across the obliquely extending edge 110a, all as is quite completely shown in FIG. 5. The horizontal portion 109a and its obliquely extending edge 110a thus function to fold the latter half of the web underneath the former half that passes under the portion 107a which is in the path of travel 106.
A right-hand folding board 100 is positioned just behind the left-hand board 99 in the path of travel 106, and the top fold 101a from the previous board 99 is trained over the horizontal portion 109 of the board 100. Web is folded by the board 100 in substantially the same manner as by the board 99, except that the told is made on the opposite side. One half or fold 1010 of the web from a roll 101 passes underneath the portion 107 of the board 100 and is thus positioned on top of the upper fold 101a produced by the previous board 99. The other half of the web from the roll 101, which is on the right side as seen in FIG. 5, passes under the portion 108, thence under the horizontal portion 109, and is folded under by the obliquely extending edge 110. In view of the fact that the upper fold of the web from the previous folding board 99 travels over the horizontal portion 109 of the board 100, the right-hand half 101d of the web on the board 100 is folded underneath not only the left half 1010 of the web on the board 100, but also underneath the top fold 101a from the previous left-hand board 99. Thus, the two boards produce a stack of interfolded tissues having upper and lower folds 101a and 101b from the left-hand board 99, and upper and lower folds 101s and 101d from the right-hand board 100, with the folds 1010 and 101d being respectively above and below the upper fold 101a from the board 99.
Subsequent, alternately arranged, left and right boards 99 and 100 each function, as will be understood, to provide folds just below the top fold from the previous board so that a stack of interfolded tissues, such as shown in FIG. 6, having folds 101a to 161k, results.
The pressure feet 112 of the wheel 113 function to crease the interfolded web W as the wheel 113 is rotated, and each cutter 63 is actuated when the corresponding pressure foot is positioned substantially vertically over the compressed bundle of tissues to cut the tissues into clipS 115. The clips 115 of tissue have any entrapped air squeezed from them by the belts 116 and 118, which are respectively supported by rollers 117 and shoe 119, so that the tissue clips 115 have a nearly uniform uncompressed height.
The clips 115 are inserted into the buckets 139, and the clips are slid from the buckets between the platens 120 and 121 of the compressor shown in FIG. 7. The chains 122 and 123 are driven, and the platens 120 and 121 are moved toward each other due to the action of the cams 128 and 129 as the chains move, in order to compress the clips of tissue. The tissue clips 115 are removed from between the platens in substantially compressed condition after the clips pass beyond the cams 128 and 129 and the clips 115 are then packed into dispensing cartons 131, each of which has a slot 132 on its upper face through which the tissues may be withdrawn one at a time. In view of the fact that the tissues are interfolded, the withdrawal of the top tissue causes the tissue immediately therebelow to be partially drawn through the slot so that it may be easily grasped for usage. The cartons 131 are made of paperboard and, as shown, are in the form of boxes having rectangular sides, top and bottom.
The compressing machine illustrated in FIG. 7 thus functions to compress the tissue clips 115, leaving them with a height substantially less than their uncompressed height. Although the illustrated apparatus and method may obviously be used with clips 115 containing many different numbers of tissues; as an example, the apparatus and method permit the packing of 350 tissue plies or 175 two-ply tissues into a 2-inch high box allowing a substantial air space between the top of the clip and the top of the box 131. Such a clip prior to compression has a height of about 2.6 inches, and the compression step reduced the height of the clip just after compression to about one inch. Assuming a tissue moisture content of /2 percent, the cams 128 and 129 in the compressor illustrated in FIG. 7 may be so set as to compress the clips 115 from the 2.6 inch height to inch; and the speed of the machine, although this is not critical, may be such as to maintain the tissues so compressed for about one second. Such a compression corresponds to 440 pounds per square inch. As the platens 120 and 121 pass beyond the cams 128 and 129 so as to release compression on the clips, the clips re-expand from /8 inch to the one inch height. The clips are then put into their boxes 131, and it is contemplated that the tissues shall be stored as so packed for a predetermined length of time prior to usage, such as for a period of at least two weeks.
As has been previously described, the actions of the doctor blade 22 in creping the tissue from the Yankee drier drum to a 2.2 crepe ratio, for example, and the subsequent elongating of the tissue by the rewinder 28 for taking out most of the creping of the tissue results in a relatively soft limp tissue. The creping, however, produces a myriad number of sharp peaks in the paper which remain. The clips 115 in being compressed between the platens 120 and 121 have these peaks dulled or depressed so that the tissues are in effect smoother sheets and are thus of higher quality for facial use. The tissue thu in eifect has an improved feel for use as a facial tissue due to the compression. The sheet thus is worked not only by the doctor blade in creping, the rewinder 29 in stretching the tissue and calendering it, but also by the compressor illustrated in FIG. 7 in compressing it.
During the storage period for the tissues after packaging in the boxes 131, the clips re-expand to some extent, such as to 1% inch to 1% inch for the 350 ply clip previously mentioned. Although the moisture content of the tissues has been brought to 5 /2 percentil percent as previously mentioned by the moisture adding mechanism 41, which is that moisture content that remains substantially the same in the humidities commonly encountered in which the tissues are used and the hard rolls 34 are stored, nevertheless, the actual height to which the tissues re-expand in this storage period varies principally due to the different atmospheric humidities in which the tissues are stored for this period. If the humidity is about 75 percent, for example, the increase in height of the packaged clips will be to about 1% inch while if the humidity is quite low, the tissues may re-expand to only the 1% inch height (this latter re-expansion during storage is considered abnormally low). It is quite desirable that the tissues shall not re-expand to the full 2 inch height of the box, since initial dispensing of the tissues would thus be made relatively difficult. It is contemplated that the tissues on re-expansion during storage in the cartons for an indefinite length of time, such as two weeks or a month, shall not have an uninhibited height more than the height of the cartons and shall preferably have a height somewhat less than carton height so that the tissues may dispense easily and do not bulge the tops and bottoms of the cartons.
The compression step by the machine illustrated in FIG. 7 has the function of jamming the fibers on the faces of the tissues together so that the fibers interlock to some extent to thus form interfacial bonds. The initial reexpansion, just after compression between the cams 128 and 129, has the effect of breaking some of these interfacial bonds with accompanying breakage of some of the fibers on the faces of the tissues. One by one the fibers break loose from each other on contacting sheets; and as one fiber breaks, it releases more force on a next one so that it breaks, and this process continues until the tissues are not so closely associated. During the two weeks storage period this process continues, the fibers on the surfaces of the tissues being broken to some extent with an accompanying lessening of the interfacial bonding. This reduction of interfacial bonding and breakage of surface fibers has the elfe-ct of increasing the bulk and rendering the tissue more limp. Both of these qualities are desirable in a facial tissue, and thus it is preferable that this storage take place prior to usage, in order that the tissues may not be of relatively low bulk and relatively stiff. In this connection, although the tissues may be used as single plies, preferably the two-ply tissue is used, since a twoply tissue tends to be more soft and less stilf than a single ply tissue. The basis weight of the tissues is not considered critical, however, in actual usage a 7.6 basis weight (uncreped) per ream (2800 square feet) has been use As has been previously mentioned, the moisture content of the tissues just prior to compression is preferably maintained at 5 /2 percent and in the range of 5 /2 percent i1 percent, which is a compromise moisture content corresponding to the humidities of the air in which the paper before compression is generally stored. In this connection, it may be mentioned that in order to obtain the ultimate uniform compressed clip heights desired, the action of the compressor as illustrated in FIG. 7, and particularly the distances between the cams 128 and 129, should preferably be changed with changes in moisture content; with a greater pressure being applied to the clips at the low end of the range, at 4 /2 percent moisture content, as compared to the pressure at the high end of the range, 6 /2 percent moisture content.
Various carton heights may be used with the compressed tissues of the invention. For example, 200 tissue plies may be packed into a 1% inch high carton, 400 plies may be packed into a 2% inch high carton, and 600 plies may be packed into a 3 /2 inch carton.
Assuming that the compression is performed with tissues having the preferred moisture content of 5.5 the following table indicates, as an example, the gap in inches between the platens 120 and 121 and the corresponding pressures applied to the tissue stacks for packing the tissues in various sized cartons with the tissue stacks being packed sufiiciently loosely in the cartons for easy dispensing, even assuming that the filled cartons are stored at high humidities, such as 75 percent, causing a relatively large growth of the tissue stacks after packing. The gaps between the platens on the basis of 200 plies or individual sheets (100 two-ply tissues), in each case, is also indicatcd:
Of course, the paper furnish used for the tissues and also other factors may vary, so that actually a variation of is contemplated with respect to the pressures above listed. In the above example, the various gaps are particularly applicable to tissue clips, weighing about 328 grams for 400 plies in bone dry condition. The sheets when folded have about 42 square inches surface area and are about 8% inches by 9% inches. The thickness of the particular tissues used was about .004 inch.
The relationship between the gap of the platens in compressing the tissue stacks (on the basis of 200 plies) and the pressure thereby applied by the platens is shown by the graphs of FIGS. 14 and 15. It will be observed that the pressure varies widel at high pressures and relatively small gaps and varies relatively slightly at relatively large gaps and small pressures.
Although the invention is preferably practiced with the tissue moisture being at 5.5% or thereabouts, the same end bulk of the tissue stacks may be obtained at Other moistures. For example, at 4% moisture and at 10% moisture contents of the tissue, the following gaps and pressures may be utilized to obtain the same bulk of the compressed tissue stacks:
The quality of the tissues is indicated approximately by an arbitrary measure of stiffness such as is shown in the ordinates of FIG. 16. This figure shows the relationship between the gap G in inches of the platens for a ZOO-ply tissue stack and the resulting stiffness of the tissues. Using the stiffness scale of the graph, a stiffness above three may be considered generally objectionable for facial tissues, while stiffnesses below three are satisfactory. Stiffnesses below 2 or 2.5 are very satisfactory. It will be observed from the graph that for very small gaps, the resulting tissue stiffness rises above three, and hence these gaps with the resulting high pressures would be objectionable. As is apparent from the graph, larger gaps (and hence smaller pressures) are usable with higher moisture contents for obtaining the same stiifnesses.
In order for the stacks of tissues to remain permanently compressed so that there is a substantial saving in space,
substantial pressures (at gaps that are substantially less than the initial uncompressed height of the stacks) should be used. FIG. 17 shows the relationship between the gap in inches and the ultimate bulk or height of a ZOO-ply tissue stack. The bulk was measured at the end of 14 days after compression and after storage of the stacks at a high relative humidity of As will be observed, as an example, if the gap is /2 inch for stacks at a moisture of 10%, the bulk is reduced from about 2 inches (uncompressed) to about 1.2 inches. Likewise, other readings of eventual bulk may be obtained from the FIG. 17 graph.
FIG. 18 shows the variations in bulk of stacks of 200- ply tissues that may be expected for various compressed conditions depending on the gap used during compression. For example, if a one-inch gap is used, the variation in height of a number of stacks at the end of 14 days is about inch. On the other hand, the variation in height of uncompressed stacks is inch. Since the variation is so much less for compressed stacks as compared to uncompressed stacks and is less if the gap is decreased, it will be understood that packing of the stacks after compression may be in smaller sized cartons that need not provide for large variations of tissue bulk.
A stiffness rank above approximately three is generally considered undesirable for facial tissues; and it will be understood that, in order to make the compression step economically worthwhile, a substantial ultimate reduction in issue bulk should be obtained. A reduction in bulk from about 2 inches to 1.75 inches (for a 200- ply tissue stack, referring to FIG. 17), for example, makes the compression step economically desirable. The gaps that should be used are below .90 inch, .70 inch, and .63 inch corresponding to relative humidities of 10%, 5.5% and 4% at the ultimate bulk of 1.75 inches as is apparent generally from FIG. 17. On the other hand, referring to FIG. 16, it is obvious that if the gaps are too low, undue stiffness of the tissues results. For stiffnesses below three, the gaps should be greater than about .42 inch, .300 inch and .27 inch which correspond respectively to 10%, 5.5% and 4% moisture levels. For a moisture content of 4%, the gap per 200 tissue plies should preferably be between .27 inch and .63 inch; for a moisture content of 5.5%, the gap should be between .300 inch and .70 inch; and for a moisture content of 10%, the gap should be between .42 inch and .90 inch. The corresponding -pressures of compression in pounds per square inch are approximately 1350 to 28 for 4% moisture; 890 to 15 for 5.5% moisture; and 140 to 4 for 10% moisture, the graphs of FIGS. 14 and 15 showing generally the relationship between compression pressure and gap.
Corresponding desired limits of pressure exist for the other tissue moistures at which compression may take place. These limits are set forth in the graph of FIG. 19. In addition to the pressure limits above mentioned, it will be observed from the FIG. 19 graph that the desirable pressure limits are approximately (in pounds per square inch) 18. to 1000. for 5% moisture; 12.5 to 720. for 6% moisture; 9. to 500. for 7% moisture; 7. to 340. for 8% moisture; 5. to 220. for 9% moisture, and 3. to for 11% moisture.
Compression of tissues according to the invention has been found to produce clips or stacks of tissues that have a bone dry density between 2.75 grams per cubic inch to 3.95 grams per cubic inch. These densities correspond to 278 to 400 thicknesses of the tissue paper per inch. It will be understood that there are twice as many thicknesses in a certain clip or stack of tissues as there are plies or sheets in view of the fact that each tissue of two plies and each sheet has been folded over. These values of thicknesses per inch and density are applicable to clips of tissues which have freely expanded within their cartons during an indefinite storage time, such as of 2 weeks or longer. Each of the tissue stacks within the cartons, it will be understood, as an uninhibited height which is the same or less than the internal height of the carton, so that the tissues may be freely dispensed and so that they do not cause bulging of the carton. These thicknesses per inch and densities allow the use of an Tissues Thick- Carton Clip Thick- Density (2-Ply) Plies nesses Height Height nesses (gr./cu.
(Inches) (Inches) per Inch in.)
100 200 i 400 1% 1-1 As 400-278 395-2. 75 200 400 800 2% 2?% 400-355 3.95-3.51 300 600 1 1,200 3% 34% 400-343 3.95-3.39
Referring to the above table, in explanation, the number of plies listed are the number of sheets that are in the clip which is packaged in the particular size of carton that is listed under carton height. Each individual tissue contains two plies so that the number of tissues is half the number of plies. The clip heights listed in the above table are the heights of the clips within their cartons after the re-exp-ansion that takes place during an indefinite storage time, such as, for example, of two weeks or longer. The column entitled thicknesses lists the total number of thicknesses in each clip which is twice the number of sheets or plies due to the fact that each tissue is folded over on itself in the clip. In the column entitled thicknesses per inch, the number of thicknesses per inch of clip height after this re-expansion are indicated. It will be observed that the number of thicknesses of paper per inch of clip height varies from 400 to 278. The density of the re-expanded clips is in the Density column of the table and is in grams per cubic inch. It is to be noted from the table that the densities vary from 2.75 grams per cubic inch to 3.95 grams per cubic inch. The tissue stacks, according to the table, have heights (the stacks being unrestrained and exerting substantially no pressure on their cartons) from 1 inch to 1 inches, 2 inches to 2 inches and 3 inches to 3 /2 inches, respectively. The densities are given for the paper in bone dry condition and if measurements of these tissues are made at various moisture contents, the densities measured, of course, will be greater. For example, in lieu of the densities between 2.75 and 3.95 grams per cubic inch, the densities will range between 2.91 grams per cubic inch to 4.19 grams per cubic inch at 6 percent moisture content. The moisture contents are on the basis of weights, the weight of a clip including the weight of the moisture being used as the basis. 6% moisture content, for example, indicates that the moisture by weight amounts to 6% of the weight of the clip prior to removal of moisture therefrom. Although the figures given in this table are considered important regardless of variations in basis weight and crepe ratio, they are considered particularly important for a final crepe ratio of about 1.2 and a drier basis weight of about 7.6 pounds per ream of 2880 square feet.
The interfolded tissues are used by withdrawing them one by one from the carton 131 through the slot 132 in the top of the box. The withdrawal of one tissue automatically draws the top fold of a following tissue partially through the slot 132 so that the succeeding tissue is easily accessible. The interfacial bonding which exists between adjacent tissue folds due to the compression assures that the succeeding sheet will be drawn through the slot 132, and this interfacial bonding is particularly important in connection with interfolding of the type illustrated in which there are no bonds of tissue between adjacent tissues.
Our improved method of manufacturing tissues provides boxed clips of tissue that have a substantially uniform height which is less than previous uncompressed clips of tissue. Three hundred fifty ply clips may easily be packed int-o a 2 inch high box with sufficient space remaining between the top of the clip and the top of the box, so that the tissues may be readily withdrawn through the slot in the box. Such a quantity of tissue previously, without compression, would have required a box of about 3% inches high. There is thus, for the same number of tissues, a considerable saving of space, not only on dealers shelves, but also invehicles used in transporting the tissues, with consequent monetary savings.
The tissues manufactured in accordance with our improved methods furthermore are of improved quality as compared to prior tissues. The tissues made according to our invention are desirably soft and limp, and they are smoother than prior uncompressed tissues, due to the fact that the sharp peaks produced by the creping have been dulled or depressed by the compression. The uninhibited re-expansion of the tissues within their cartons allowed by the diiference in height between the clips and cartons during the storage period of the clips after packaging and compression results in softer tissues; and, although the peaks due to the creping tend to again rise with the release of interfacial bonding that occurs during storage, the original condition of the high peaks of crepe is never again reached, so that the tissues remain smoother.
Due to the fact that the tissue is preferably passed through the rewinder 28 with a relatively low moisture content, the undesirable stiffness and paperiness that would occur if the tissue had a relatively high moisture content when passed through the rewinder are not obtained. Nevertheless, the relatively high moisture content of 5 /2 percent :1 percent desired in the hard roll exists due to the additional moisture added subsequent to calendering, and thus large variations of moisture content throughout the hard roll or the hardening and stiffening of the tissue in the hard roll, particularly at the center of the roll, do not exist.
The compression of the tissue clips has the effect on the tissues of providing interfacial :bonding which is particularly advantageous when the tissues are interfolded by an interfolder of the type that does not provide any tissue bonds between adjacent sheets. The interfacial bonding exists even after prolonged storage periods and assures that leading portions of succeeding tissues are drawn through the slot in the top of the box, so that the succeeding tissues are easily available. The dry creping operation tends to raise lint in the tissues apparently by splintering fibers loose from the body of the web, and the compression operation has the advantageous function of rebonding the linty fibers back into the body of the tissues, so that the latter become less linty.
FIGS. 20A and 20B illustrate the advantages of the present invention. The same number of tissues may be packed in and occupy a carton 200 which is only slightly more than half the size of a carton 201 for the original uncompressed tissues. For example, in lieu of a 4 inch high carton for 200 2-ply tissues, a 2% inch high carton is satisfactory. The slack fill that occurs as a general rule and which is quite variable, in connection with the uncompressed tissues, as illustrated in FIG. 20A, is overcome; and only a slight spacing, such as of A inch or less, may be used satisfactorily in connection with the compressed tissues as is illustrated in FIG. 20B.
As is apparent, the invention may also be utilized in connection with tissues which are folded in some configuration other than interfolding. The invention is illustrated in FIGS. 21 and 22 in connection with C-folded tissues 202, FIG. 21 illustrating an uncompressed stack 203' of such C-folded tissues which are each preferably of two plies similar to the interfolded tissues previously described. Each of these tissues has a central base portion 202a and has side edge portions 202]; and 202:: which are folded over the central portion 202a and have a space 292d between them. The base portion 202a may, for