US3230136A

US3230136A - Patterned tissue paper containing heavy basis weight ribs and fourdrinier wire for forming same

Info

Publication number: US3230136A
Application number: US371870A
Authority: US
Inventors: Kenneth V Krake
Original assignee: Kimberly Clark Corp
Current assignee: Kimberly Clark Corp
Priority date: 1964-05-22
Filing date: 1964-05-22
Publication date: 1966-01-18
Anticipated expiration: 1983-01-18

Description

Jan. 18, 1966 K. v. KRAKE 3,230,136

PATTERNED TISSUE PAPER CONTAINING HEAVY BASIS WEIGHT RIBS AND FOURDRINIER WIRE FOR FORMING SAME Original Filed June 16. 1961 6 Sheets-Sheet 1 Jan. 18, 1966 v. KRAKE 3,230,136 PATTERNED TISSUE PAPE ONTAINING HEAVY IS WEIGHT RIBS AND FOURDRINIER WIRE FOR FORM SAM Original Filed June 16, 1961 6 ets-Sheet 2 K v. KRAKE 3,230,136 PATTERNED TISSUE PAPER CONTAINING HEAVY BASIS WEIGHT RIBS Jan. 18, 1966 AND FOURDRINIER WIRE FOR FORMING SAME 6 Sheets$heet 5 Original Filed June 16, 1961 Jan. 18, 1966 a K. v. KRAKE 3,230,135

PATTERNED TISSUE PAPER CONTAINING HEAVY BASIS WEIGHT RIBS OURD 6 961 t Jan. 18, 1965 K. v. KRAKE ,2

PATTERNED TISSUE PAPER CONTAINING HEAVY BASIS WEIGHT RIBS V AND FQURDRINIER WIRE FOR FORMING SAME Original Filed June 16, 1963. 6 Sheets-Sheet 5 .Fan. 38, N66 K. v. KRAKE 9 PATTERNED TISSUE PAPER CONTAINING HEAVY BASIS WEIGHT RIBS v AND FOURDRINIER WIRE FOR FORMING SAME Original Filed June 16, 1961 6 Sheets-Sheet 6 United States Patent Continuation of abandoned application Ser. No. 117,702,

June 16, 1961. This application May 22, 1964, Ser. No. 371,870

6 Claims. (Cl. 162-111) This application is a continuation of my copending application Serial No. 117,702, filed June 16, 1961, now abandoned.

The invention relates to cellulosic products and, more specifically, to relatively light weight paper tissue sheets which are particularly suitable for facial usage.

It is an object of the present invention to provide an improved paper tissue which is patterned in a uniform manner by relatively light and heavy basis weight portions so as to have a cloth-like appearance.

It is also an object of the invention to provide a relatively light basis weight paper tissue which is very limp both in the longitudinal direction and also in the transverse direction.

It is a more particular object of the invention to pro vide such a tissue which has been worked by creping and by subsequent stretching in the longitudinal direction so as to be limp in this direction and which has longitudinally extending light weight stripes so as to make it very limp in the transverse direction.

In brief, the patterned paper tissue of the invention is made up of a plurality of longitudinally extending relatively heavy basis ribs spaced by relatively light basis weight stripes. The paper fibers in the ribs, for the most part, extend longitudinally while the fibers in the stripes, for the most part, extend transversely, so as to bridge and connect adjacent ribs to give strength and limpness to the sheet transversely of the sheet.

It is also an object of the invention to provide an improved method and to an improved Fourdrinier drainage belt for making such patterned tissue.

The invention consists of the novel cellulosic tissue sheets and of the novel manner for making such sheets 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 forms of such sheets and modes of manufacturing them, illustrated with reference to the accompanying drawings, wherein:

FIG. 1 is a side elevational view, partially schematic, of a paper web forming machine, including a Fourdrinier forming fabric movably trained in the form of a loop about a plurality of supporting rolls, a stock inlet for applying stock onto the fabric, and a drier drum having a doctor blade applied to it for doctoring web off the drum;

FIG. 2 is a schematic view of the terminal end of the papermaking machine shown in the preceding figure and also showing a soft roll into which 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 rolls;

"ice

FIG. 4 is a fragmentary plan view of the forming fabric used in the machine illustrated in FIGS. 1 and 2;

FIGS. 5 and 6 are sectional views taken respectively on lines 5-5 and 6-6 of FIG. 4 in the directions indicated;

FIGS. 7 and 8 are side views on respectively relatively small and large scales of the drier drum of the papermaking machine and the doctor blade associated with the drier drum;

FIGS. 9 and 10 are photographic plan views on an enlarged scale of paper tissue made with the papermaking apparatus illustrated in the preceding figures, the two opposite sides of the paper tissue in contact with and out of contact with the drier drum being respectively illustrated in these two views; and

FIGS. 11 and 12 are views corresponding to FIGS. 9 and 10 but on still further enlarged scales.

Like characters of reference designate like parts in the several views.

Referring now to FIGS. 1 and 2, the illustrated papermaking machine may be seen to comprise an endless fabric belt 10 (usually termed a Fourdrinier wire) movably positioned about a breast roll 11, a couch roll 12, table rolls 13 and a guide roll 14.

A felt 40 in the form of a loop extends around a plurality of relatively

large diameter rolls

41, 42 and 43 and a plurality of small diameter idler rolls 44. The roll 41 has a nip with the couch roll 12, and the roll 43 is a pressure roll and has a pressure nip with a steam heated drier drum 45. A roll 46 has a nip with the roll 42 so as to form a press for the felt 40 between the

rolls

42 and 46.

A doctor blade 47 is held in forceful contact with the drum by any suitable holding structure (not shown). The blade 47 is flexible in accordance with conventional practice and is flexed to some extent by its contact with the drum. The blade 47 is ground on its edge so as to have a surface 48 which extends at an obtuse angle with respect to the adjacent side of the blade, with the blade edge 49 formed by this surface 48 and the adjacent side of the blade being that part of the blade in contact with the drum 45.

A reel 50 supported by a standard 51 and driven by a motor 52 may, for example, be provided for taking up web W which is produced by the papermaking machine and forming it into a roll 53 (which may be termed a soft roll).

The paper web W is transferred from the fabric 10 onto the felt 40 beneath the roll 41 and has water expressed from it by the

press rolls

42 and 46. The felt 40 not only carries the web W, but it also has the function of extracting water from it as is well known. The paper web is transferred from the felt at the roll 43 onto the drier drum 45, and the latter dries the web. The doctor blade 47 scrapes the web W from the surface of the drier drum 45, and, in doing so, it crepes the Web. The drum 45 is heated for drying the web W, as by means of steam within the drum, and the web W is substantially completely dry, at least dry to the touch, having less than 10 percent moisture content by weight when it is creped by the blade 47 from the drum. The blade 47 is operative to provide the web W with a substantial crepe ratio, such as on the order of 2.2. Crepe ratio is defined as the length of a certain amount of web W on the drier drum 45 divided by the final length of the same amount of web, which in this case is just subsequent to the creping operation. For a crepe ratio of 2.2, the final length of paper is 5 /2 inches for a foot of paper on the drier drum 45. The blade 47 in creping the web W causes the web, as illustrated in FIGS. 7 and 8, to have relatively sharp peaks 54 on its surface which has previously been in contact with the surface of the drum and relatively blunt or round peaks 55 on the opposite surface of the web which is that surface that has been out of contact with the drum. The creping blade may be adjusted with respect to the drier drum so as to have more or less pressure; the blade 47 may be ground differently to change the angle of the surface 48 with respect to the adjacent side of the blade; and the angle a (which may generally be on the order of 50 to 55 degrees) of the blade with respect to the drum 45 may be changed so as to change the creping effect of the blade; however, the blade may, for example, provide about 40 to 60 peaks 54 per lineal inch of Web in its creped condition. After creping by the blade 47, the web W is wound by the roll 50 into a soft roll 53.

Incidentally, the web forming section, the felt section and the drier section of the papermaking machine may have the usual variations all of which are well known in the art; and the fabric 10, the felt 40 and the drier drum 45 may all be driven by conventional driving mechanism, the particular papermaking machine shown in the figures being shown for exemplary purposes only.

The fabric is of such construction that it produces a web W when used in the manner indicated which has longitudinal ribs of relatively heavy basis weight separated by stripes of light basis weight as will be subsequently described.

.In converting the web W for subsequent use, particularly as tissues for cleansing or facial purposes, a so-called calender or rewinder 56 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 53 are r-otativelymounted 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

57, 58 and 59, idler rolls 60, and a pair of rolls 6] and 62 adapted to contact a so-called hard roll 63 of the web W which has passed through the rewinder.

The soft rolls 53 are each driven from a suitable prime mover, such as an electric motor 64; and each of the

rolls

57, 58 and 59 are respectively driven from other prime movers, such as electric motors 65, 66 and 67. The roll 61 is driven by a prime mover, such as an electric motor 68.

In the operation of the rewinder, web W is drawn from each of the rolls 53 and is passed consecutively between the

rolls

57, 58 and 59 and is finally wound into the hard roll 63. The pairs of

rolls

57, 58 and 59 have pressure nips between them so as to compress and calender the web as it passes between the rolls. Furthermore, the various rolls in the rewinder 56, which are connected to the motors 64 to 68, are so driven thereby that the web is stretched as it passes through the rewinder, the total stretch preferably being such as to decrease the creping from the value of 2.2 previously mentioned to between 1.05 and 1.3 and preferably about 1.2, using the length of the web on the drier drum 45 as a basis of comparison. A foot of tissue on the drier drum that was decreased in length by the doctor blade 47 to 5 /2 inches has thus been stretched back to a length of about 10 inches for the 1.2 value, as it is wound into the hard roll 63. The restretching of the web by the rewinder and the calendering action by the

rolls

57, 58 and 59, acting with pressure on the web as it passes between the rolls augments the effect of the doctor blade 47 in rendering the tissue very soft and limp, so that the tissue has these desirable qualities for use as a facial tissue. Incidentally, practically all of the web stretching, about 85 percent of it, in such a rewinder is preferably done between the soft rolls 53 and the first calender rolls 57; and the subsequent rolls 58 and 59 function principally to calender, so that the web not only is soft and limp, but in addition has a smooth surface. The web W after being wound into the rolls 63 may be cut by any suitable mechanism into individual two ply sheets, such as of about 8 /2 inches by 10 inches, and these may be packed into suitable cartons for subsequent usage as facial tissues.

As previously mentioned, the fabric belt 10 is of such construction and is so used that it produces a longitudinally ribbed pattern in the resulting web W. A fabric suitable for this purpose is illustrated in FIGS. 4, 5 and 6 and comprises pairs of warp wires 69. The warp wires 69 of each pair lie in contact with each other and are in substantially the plane of the belt 10, and the warp wire pairs thus in effect each form a warp strand 70 which is twice as wide in the plane of the belt 10 as it is thick in the direction normal to the plane of the belt. The warp strands 70 are interwoven with shute wires or strands 71, with each of the shute strands 71 on thepapermaking side of the fabric looping over single warp strands 70 and under two warp strands 70 and the shute strands being staggered with respect to the warp strands over and under which the shute strands extend, all as will be apparent from FIG. 4 showing the papermaking side of the fabric. There may be, for example, 36 warp strands or pairs of wires 69 per inch; and there may, for example, be 68 shute wires per inch. The warp strands 70 extend longitudinally of the fabric 10, or in the machine direction, and the shute wires 71 extend transversely of the fabric or in the cross machine direction. The strands for one example of the fabric may have the following dimensions: the warp wires 69 may each have a diameter of .0067 inch, and each of the shute wires 71 may have a diameter of .00875 inch. Each of the warp strands 70 in effect forms a region extending longitudinally of the fabric 10, that is, in the machine direction, which has a width of .0134 inch. The wire is so woven that the knuckles 72 of the shute wires 71 on the papermaking side of the wire, as illustrated in FIG. 4, are about .002 inch above the plane of the knuckles 73 of the warp wires 69. On the bottom or suction box side of the wire, the shute wire knuckles 74 may extend downwardly or inwardly .0045 inch farther than the warp knuckles 75. The total thickness of the wire may be about .0193 inch. The openings through the wire are rectangular with the longest dimension in the shute direction. The projected size of the openings through the fabric looking directly down on it, as in FIG. 4, are .0054 inch by .0142 inch, and the projected open area is equivalent to about 20.1 percent of the total. Although the warp and

shute wires

69 and 71 may be made of different materials, such as bronze and stainless steel, they may both well be made of the same material, such as bronze.

A fabric 10, as illustrated in FIGS. 4, 5 and 6, has been found to produce a creped tissue as illustrated in FIGS. 9, 10, 11 and 12. The tissue comprises a series of rela tively heavy basis weight ribs 76 alternating with stripes 77 of light weight basis. The paper product also has a plurality of transversely extending peaks 78 which are visible on one side of the sheet, which is that side away from the surface of the drier drum 45 and which is illustrated in FIGS. 10 and 12. These peaks correspond with the relatively sharp peaks 54 as seen in FIG. 8, which are formed by the edge 49 and slanted surf-ace 48 of the doctor blade 47. The other side of the product, as illustrated in FIGS. 9 and 11, does not have these peaks, since the peaks 55 as seen in FIG. 8 formed by the edge 49 and surface 48 are not as pointed as are the peaks 54.

There are as many ribs 76 and stripes 77 as there are warp strands 70. The particular fabric above mentioned had 36 pairs of warp strands 69 per inch, and hence the tissue illustrated in these figures as formed by this particular fabric likewise has, per inch, 36 heavy basis weight ribs 76 and 36 relatively light basis weight stripes 77, it being understood that the ribs 76 and stripes 77, like the 3 warp wires 69, extend in the machine direction as the web is creped from the drier drum 45 by the doctor blade 47.

In an actual paper product according to the invention, there may be quite a wide variation of numbers of fibers in the ribs 76 and in the stripes 77. It has been found by actual count in such a paper product, after rewinding and calendering by the rewinder 56, that the number of fibers per millimeter length of rib 76 varied from 55 to 120, and the number of fibers per millimeter length of stripe 77 varied from zero to 20. The stripes thus had a multitude of minute openings through them, such as the openings 77a, 77b and 77c illustrated in FIG. 11. The average number of fibers in the rib was 82 per mm., and the average number in the stripe was 12 per mm. The stripes 77 were about .07 inch wide and the ribs 76 were about .2085 inch wide. Thus the approximate ratio of rib width to stripe width is .20-85/ .07 or 2.98, and the ribs are thus about 3 times as wide as the stripes.

The drier basis weight (the basis weight of the web before creping from the drier 45) may for this material be about 7.6 pounds per 2880 square feet; and the finished basis weight, subsequent to creping by the doctor blade 47 and stretching and calendering by the rewinder 56, may be about 9.9 pounds per 2880 square feet (this figure is for -a single ply-the basis weight is double or 19.8 pounds per 2880 square feet for the double ply product mentioned in connection with the rewinder 56). The average basis weight after calendaring and rewinding (the finished basis weight) of the ribs 76 may be approximately 11.7 pounds per 2880 square feet of rib, and the basis weight of the stripes 77 may be about 5.1 pounds per 2880 square feet of stripe. Thus, the ratio of the basis weight of the ribs to the basis weight of the stripes is 11.7/ 5.1 or 2.3, which is slightly more than 2.

From FIGS. 11 and 12 showing the tissue paper prodnot on a greatly magnified scale, it will be observed that most of the fibers in the stripes 77 extend transversely of the sheet, bridging and connecting adjacent ribs. On the other hand, the fibers in the relatively heavy basis weight ribs 76 generally extend longitudinally of the product (in the machine direction and in the direction in which the ribs and the stripes extend). The longitudinal ribs 76 thus account for most of the basis Weight to the product as a whole, while the fibers in the stripes 77 function to provide transverse strength to the sheet by connecting the adjacent ribs 76 together.

The fabric 19 in operation provides the relatively light basis weight stripes 77 due to the relatively large width of the warp strands 79, each of which includes a pair of warp wires 6?. These warp pairs impede drainage of the t white water from the stock deposited on the fabric 10, and since the fibers follow the stream lines of the white water flowing through the fabric, as the stock is being drained and the web is being formed, the fibers tend to move and to be deposited between the warp pairs and over the drainage openings defined by adjacent warp and shute wires and into the valleys between the warp strands 70. The heavy basis weight ribs 76 thus correspond in spacing and more or less in extent with the drainage openings between adjacent Warp and shute wires and with these valleys between adjacent warp strands 70.

It is considered important, however, that the shute knuckles 72 on the papermaking side of the fabric 10 illustrated in FIG. 4 are higher than the warp knuckles 73, since this attribute of the fabric 1!) apparently provides the bridging fibers in the stripes 77 connecting adjacent relatively heavy weight ribs 76. Apparently at the beginning of deposit of stock on the fabric 10, when the white water first begins to drain through the fabric and into the breast roll 11, there is a relatively high velocity of white water flow through the drainage openings between the shute and warp wires and the relatively high transversely extending shute knuckles 72 tend to turn the fibers, which initially are deposited on the wire generally in the machine direction, so that they extend transversely and parallel with the shute knuckles". As the drainage openings between the warps and shutes fill up with fibers, the velocity of the white water flow through the fabric becomes less, and the fibers then tend to remain in the same direction in which they are deposited on the fabric, namely in the machine direction, and they line up with the drainage openings in the fabric between the warp pairs and form the relatively heavy basis weight ribs 76 composed principally of such longitudinally extending fibers. Thus the tissue web composed of longitudinal ribs 76 bridged by transversely extending fibers in the stripes 77 is formed.

The advantageous result of such a deposit of fibers, with an initial relative few in the transverse direction bridging a subsequently laid relatively large number extending in longitudinal ribs, is a ribbed paper tissue that has practically the same strength in both directions as ordinary facial tissue for which there is no attempt to form ribs or to direct fibers in the transverse machine direction. Due to the large number of fibers extending longitudinally of the sheet, it is obviously very strong longitudinally. Advantageously, the sheet also is quite strong in the cross direction due to the fibers in the stripes 77 that bridge and connect adjacent ribs 76, having been turned from their original longitudinal direction by following the stream lines of stock flow around the high trans versely extending shute knuckles 72. This mode of formation results in a patterned tissue having a series of coarsely spaced heavy basis weight ribs alternating with light basis weight stripes that appears to a great extent like a piece of patterned cloth. Due to the relatively few fibers in the stripes 77, the tissue stripes are diaphanous or have a multitude of minute openings through them, and a tissue having a very high esthetic value is thus provided as compared to tissues of uniform basis weight.

Mechanically the striped tissue is very limp in both the machine direction and in the cross direction and is hence considered very valuable for facial usage. The heavy weight ribs 76 extend in the machine direction and hence might be thought on a superficial analysis to give stiffness to the sheet in this direction; however, the web W and the resulting sheet are made limper in the machine direction, due to the mechanical working of the web, that is, in particular, the creping by the doctor blade which creases the web at the

peaks

54 and 55 and thus crumples the fibers at these points to remove the stiffness from them and the subsequent straightening of the fibers, particularly at these peaks, in the rewinder 56 which removes most of the crepe and stretches the web back into nearly its original length. This working and reworking of the fibers extending longitudinally of the web thus renders the web and resulting sheet very limp in the longitudinal direction.

The doctor blade 47 and the rewinder 56 are not effective to crease and straighten any transversely extending fibers; however, inasmuch as there are only a relative few of such fibers, which connect the heavy weight ribs 76, the web W and the resulting tissue sheets are also limp in the transverse direction, even though there has been no great working of the web in this direction.

As above described, the doctor blade 47 produces the

peaks

54 and 55, and these form corrugations which, if the web were of uniform basis weight transversely, would understandably tend to stiffen the tissue in the cross direction, particularly since the tissue is not worked in this direction. The light basis weight stripes 77 extending in the machine direction apparently allow crinkling of any such corrugations in the sheet of the invention to undermine the strength that would be provided by such corrugations, and the sheet of the invention is considerably limper crosswise for this reason.

The use of the relatively short high shute knuckles 72, bridging only single pairs of warps on the papermaking side of the fabric, is considered important. Relatively long high shute knuckles bridging at least two adjacent pairs of warps would instead produce a relatively uniform basis weight tissue without ribs and stripes, due to the fact that the long shute knuckles would support the fibers and cause the fibers to drape over the knuckles without allowing the fibers to reach the twin warps for formation of the light basis weight stripes as above described.

It has also been found that such a ribbed product as shown in FIGS. 9 to 12 may be formed if the fabric illustrated in FIG. 4 is run with the shutes 71 extending in the machine direction, with the same side of the wire (shown in FIG. 4) being used as the papermaking side. There is, however, in the resulting product, not as high a ratio of the number of fibers in the dense ribs 76 to the number of fibers in the light weight stripes 77, as has been above mentioned.

The number of ribs 76 and stripes 77 in the tissue paper product may be changed simply by changing the spacing of the warp wires 69 or changing their diameters. Increasing the diameters of the Warp wires will thicken the ribs 76, while decreasing the diameters of the wanp wires will decrease the width of the ribs. Obviously, many other changes in dimensions of the wire may be made for producing a ribbed product of the type illustrated in FIGS. 9 to 12, and the dimensions of the wire are referred to above only for the purpose of example. Also, the dimensions and fiber counts of the ribbed product may be changed, and variations of these factors will now be mentioned.

If desired, the ribbed tissue may be made considerably lighter or heavier than above mentioned. The tissue may, for example, be made with a drier basis weight between 4 /2 to 20 pounds per 2880 square feet and with a finished basis weight between 5 /2 to 25 pounds per 2,880 square feet. The crepe ratio of the finished product can also be varied as between 1.00 to 1.4 for example. The number of crepes per inch of the finished product may also well be varied, as from 40 to 60, with a median of 49. The basis weights of the ribs and stripes can also be varied such as, respectively, between 6 to 18 and between 2 to 7.5 pounds per 2880 square feet of rib or stripe, for a finished web, with the median values for the ribs and stripes being 11.7 and 5.1. For drier basis weight, these values for the ribs would be 4 /2, 9 /2 and and for the stripes would be 1%, 4 and 6 (pounds per 2880 square feet of the rib or stripe as the case may be).

The average number of fibres in the stripes and ribs can also well be varied such as from 6 to 100 per mm. for the stripes and 40 to 250 per mm. for the ribs on a finished basis, with medians being 82 and 12 respectively. The ratio of rib width to stripe width is preferably about 3 to 1, but this ratio may well vary between 1 to 2 and 5 to 1.

The dimensions of the fabric may well be varied as above noted. In addition, it can be mentioned that the diameters of the warps 69 can well vary between .004 inch and .012 inch and the shutes 71 between .006 inch and .012 inch. The shute knuckles may well be about .002 inch above the warp knuckles on the papermaking side of the fabrics as mentionedthis dimension can well vary between .001 inch and .007 inch with good results. The open area of the fabric 10 Should preferably be between and I wish it to be understood that the invention is not to be limited to the specific tissue products or to the method for making the same as above described, ex cept only insofar as the claims may be so limited, as it will be understood to those skilled in the art that changes may be made without departing from the principles of the invention.

What is claimed is:

1. A patterned sheet of tissue paper consisting of a series of discrete, continuous, parallel, equally spaced, relatively heavy basis weight ribs formed of paper fibers separated by a series of relatively light basis weight stripes formed of paper fibers, the stripes being of such low basis weight that they have a multitude of minute openings through them and having a basis weight of between 2 to 7.5 pounds per 2,880 square feet of stripe, and said ribs having a basis weight more than twice the basis weight of said stripes.

2. A patterned sheet of tissue paper consisting of a series of discrete, continuous, parallel, equally spaced, relatively heavy basis weight ribs formed of paper fibers separated by a series of relatively light basis weight stripes formed of paper fibers, said stripes being of such low basis weight that they have a multitude of minute openings through them, said ribs having a basis weight which is more than twice the basis weight of said stripes and which is approximately 11.7 pounds per 2,880 square feet of rib and the ribs being about 3 times as wide as the stripes.

3. A patterned sheet of tissue paper consisting of a series of discrete, continuous, parallel, equally spaced, relatively heavy basis weight ribs formed of paper fibers separated by a series of relatively light basis weight stripes formed of paper fibers, said stripes being of such low basis weight that they have a multitude of minute openings through them and having a basis weight of between 2 to 7.5 pounds per 2,880 square feet of stripe and said ribs having a basis weight more than twice the basis weight of said stripes, the sheet having approximately 36 ribs and 36 stripes per inch.

4. A patterned sheet of tissue paper consisting of a series of discrete, continuous, parallel, equally spaced, relatively heavy basis weight ribs separated by a series of relatively light basis weight stripes, said stripes being of such low basis weight that they have a multitude of minute openings through them and having a basis weight of between 2 to 7.5 pounds per 2,880 square feet of stripe, and said ribs having a basis weight more than twice the basis weight of said stripes and having a basis weight of between 6 to 18 pounds per 2,880 square feet of rib, said ribs being made up of paper fibers most of which extend generally longitudinally of the ribs and said stripes being made up of a very much smaller number of paper fibers most of which extend transversely of the stripes so as to bridge and connect adjacent ribs, the longitudinally extending fibers of said ribs having fiexionally worked, pliant crease lines in them so that the sheet is limp longitudinally and the relatively small number of fibers extending transversely of the sheet in said stripes giving limpness to the sheet in the transverse direction.

5. An endless foraminous belt for a Fourdrinier type papermaking machine having an outer surface on which paper stock may be deposited for drainage to form a paper tissue web, said belt comprising spaced longitudinal strands extending lengthwise of the belt and spaced transverse strands extending crosswise of the belt which are interwoven together, each transverse strand passing alternately over a single longitudinal strand on said outer belt surface and then under a plurality of longitudinal strands, said strands being so crimped that said transverse strands have crests on said outer belt surface that are higher than crests of the longitudinal strands on said outer belt surface, said longitudinal strands in cross section being at least approximately twice as wide in the plane of the belt as they are thick in the direction normal to the plane of the belt.

6. An endless foraminous belt as set forth in claim 5, said longitudinal strands each being made up of a pair of round wires in substantially continuous contact with each other and lying in the plane of the belt, each of said round wires having a diameter of about .004 to .012 inch and said transverse strands being about .001 to .007 inch higher than said longitudinal strands on said outer side of the belt, and the belt having an open area of 20 percent to 25 percent.

(References 011 following page) References Cited by the Examiner UNITED STATES PATENTS Jenks 162116 Smith et a1 162-109 Weston 162-116 Harrigan 162116 Fourness et a1 162113 Specht 2458 Specht 139425.5

11/1956 Fish 162-117 6/ 1960 Muller 162113 7/ 1961 Hornbostel et a1. 162-348 1/ 1962 Voigtman et a1 1621 11 7 1962 Peterson 162--1 11 FOREIGN PATENTS 5/ 1940 Austria,

DONALL H. SYLVESTER, Primary Examiner.

Claims

5. AN ENDLESS FORAMINOUS BELT OF A FOURDRINIER TYPE PAPERMAKING MACHINE HAVING AN OUTER SURFACE ON WHICH PAPER STOCK MAY BE DEPOSITED FOR DRAINAGE TO FORM A PAPER TISSUE WEB, SAID BELT COMPRISING SPACED LONGITUDINAL STRANDS EXTENDING LENGTHWISE OF THE BELT AND SPACED TRANSVERSE STRANDS EXTENDING CROSSWISE OF THE BELT WHICH ARE INTERWOVEN TOGETHER, EACH TRANSVERSE STRAND PASSING ALTERNATELY OVER A SINGLE LONGITUDINAL STRAND ON SAID OUTER BELT SURFACE AND THEN UNDER A PLURALITY OF LONGITUDINAL STRANDS, SAID STRANDS BEING SO CRIMPED THAT SAID TRANSVERSE STRANDS HAVE CRESTS ON SAID OUTER BELT SURFACE THAT ARE HIGHER THAN CRESTS OF THE LONGITUDINAL STRANDS ON SAID OUTER BELT SURFACE, SAID LONGITUDINAL STRANDS IN CROSS SECTON BEING AT LEAST APPROXIMATELY TWICE AS WIDE IN THE PLANE OF THE BELT AS THEY ARE THICK IN THE DIRECTION NORMAL TO THE PLANE OF THE BELT.