DE2231645A1 - Soft absorbent fibrous sheet material and method and apparatus for making the same - Google Patents

Description

P. 1457

Scott Paper Company, Industrial Highway at Tinicum Island Road, Delaware County, Pennsylvania, V.St.A.

Soft absorbent fibrous sheet material and method and apparatus for making the same

The invention relates to a method of making soft, absorbent, creped, fibrous sheet materials and to soft fibrous sheet materials made by such processes.

Such sheet materials are useful for sanitary paper products, e.g. fabrics, towels and the like. In particular, the invention relates to the manufacture of a soft, absorbent, fibrous sheet material, which by unusually large mass, i.e. low density, measured by a calculated Average density through its thickness under no load and is characterized by a high TEA-to-stiffness ratio, which is at least in part due to the use of a elastomeric bonding material to provide much of the interfiber bond strength of the sheet material.

In the past and recently there has been extensive activity in the papermaking field to explore ways to give the paper webs softness without reducing their strength.

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Paper webs are liorkömrallich softened by they are finished in various ways, e.g. by embossing them, calendering or by removing them from crepe an adherent surface with a creping blade. Such procedures break with and break many the rather crumbly natural interfiber connections in the paper web that passed through while it was being scanned the hydrate bond process that occurs with papermaking connected is. However, these interfiber connections are the main source of strength in an ordinary paper web. A very low strength results from the physical interweaving of the fibers, since the papermaking fibers are extremely short in length, generally on the order of 1.6 mm or less fewer. Furthermore, they are arbitrarily deposited from a watery mud, so that entanglement is not favored will.

Further, although the breaking interfiber bonds in a previously formed web provide substantial softness primarily on the surface of such 3-seams as a result of the loose fiber ends extending therefrom, this does not help to increase the bulk, compressibility and flexibility of the product, or the To lower the density of the product, which are all characteristics that subjectively indicate to a person the softness without significantly lowering the strength of the material. This undesirable result is clearer _s when efforts are made to increase the softness of the web.

Attempts to improve this situation have creped webs in only selected spaced-apart webs Areas across its surface, e.g., by creping with a notched or serrated creping blade or

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the creping τοη of an interrupted surface, e.g. an uafangsaiäßig grooved roller with the ropes in between left with essentially all of their strength. However, such crepe patterns are necessarily produced Lines of weakness through the sheet or sheet, so that the final sheet at least in certain directions wasn't very strong. Creping or embossing the web while it is wet will reduce the Strength decreased or reduced.

When paper webs are formed by conventional papermaking techniques, they are generally between pressed two opposing surfaces, at least one of which is porous, so that the water is removed from the web will. It is common to have such tracks on the Fourdrinier wire or other shaping surfaces such as by a take-up roll or in a press section on a felt between two press rolls or on the hard surface of a cast iron Yankee dryer drum that is steam heated to Removing moisture from the web and providing a surface from which the web can be creped. In order to provide quick drying of the web it has been shown to be important for uniform contact to provide between the Ym & ket dryer surface and / the web. It has been suggested by a number of prior patents that paper webs especially those used for sanitary Paper products are used, shaped and partially dried before being subjected to mechanical pressure of such kind which would compress the structure and bring the fibers into intimate contact connections with one another. For example, here is TJS Patent No. 3,301,746 to Sanford et al should be noted. This same patent discloses that one such sheet has the knot pattern of a woven wire

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or other imprinting fabric is printed on the Yankee dryer after it is partially dried to adhere portions of the web to the surface of the dryer and cause differential creping when the web is creped by the Yankee dryer. The indented portions were used to create areas of extensive interfiber connection to provide strength to the web. Meanwhile, in areas between these indented portions, the web lacks the desired degree of strength due to the reduced amount of interfiber connection resulting from the lack of compression during formation. The interfiber binders which are present are of a hard, friable nature, ie hydrogen or hydrate binders, and deleteriously add softness to the web. Furthermore, the pressures created by the hump pattern of the woven wire are so high that they create hard parts of the web which give the resulting product a feeling of hardness. In addition, even any form of printing the web before it is at least 80 $ dry creates a loss of bulk in the web and an increase in web density, all of which are undesirable in a sanitary paper product which requires softness and absorbency.

One of the hallmarks of a sheet product, which is strength appearance is the toughness of the sheet. In essence, this is characteristic of the combination of tensile strength of the leaf and its ability to stretch. If the leaf gave him some by stretching Can absorb force to withstand the full force applied, the resulting web is tougher. It's been since It has long been known to crepe webs in various ways to create stretch and accordingly Grant toughness. However, flat paths are

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in one direction or in several different directions are creped to give it a universal or isotropic stretch "weakened and jerked by the creping accordingly not as much stretch as desired, especially if they have a relatively low basic weight, such as sanitary papers.

the area of nonwoven webs which. in general contain significant amounts of fiber that are greater than 1.6 mm (1/4 ") in length, it has been common practice to To attach binding material to spaced parts of the web, so that lasers in a few parts and maybe be connected to one another in a network across the web in order to provide strength to the web. However, they are fibers in such nonwoven webs are long enough to allow small amounts of glue to form the web To give substantial strength, since any two adjacent areas of adhesive attachment are quite wide can be separated from each other and still be able to connect a fiber in a network.

It has often been assumed that the application of binding material to a paper web in order to achieve the same strength to be granted ^ hard surfaces in the web were revealed, which destroy the sense of alertness that is desired. Also, in view of its extremely short length of papermaking fibers has been believed to be the amount of binder required and the large percentage the total area of the web that would have to be impregnated in order to impart any strength to the sheet would result in a very hard sheet which has little or no elongation and low softness characteristics.

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Previous applications of adhesives to paper webs are generally suitable from an educational standpoint soft paper unsatisfactory for sanitary paper products since such adhesives, when needed, made the webs quite hard and heavy.

One form of web that overcomes these problems is made by compression bonding material, and is preferably one elastomeric bonding material on a previously formed web containing a reduced amount of natural interfiber bonding agent and includes the creping of such webs in a manner which interconnects the joined web portions softened, which contain the strength-imparting connecting material. Meanwhile the paths are through one Lack of uniform interfiber connector through the web is characterized, as is often the case in sanitary Products is desirable to give them uniform strength, elongation and softness. Instead it is Connection material in these tracks only in Akatand standing areas exist as a result of such webs printed in a pattern with the binding material are.

It has been discovered quite unexpectedly that fibrous Sheets can be formed which have unusually high softness and bulk and which nevertheless have an elastomeric adhesive have uniform at interfiber contact points is distributed through the web. This is achieved by adding the elastomeric binding material to aqueous slurry from which the web is originally formed, as well as by substantially drying the web before any mechanical compression is applied to create and maintain mass. Such a path is even further improved

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by successively printing such a web with a pattern of binding material by which the web is adhered to a creping surface so that it differential can be creped to even more bulk and to create softness.

It was extremely surprising to discover that such webs have the very low density which is a desirable feature in disposable sanitary paper products that must be soft and absorbent in order to perform wiping functions. Furthermore, the webs have fairly uniform strength and elongation to a substantial extent, as a result of the elastomeric bonding material which provides interfiber bonds uniformly throughout the webs, as well as the differential creping operation where it is needed. The webs also have good strength or the ability to absorb force without tearing or breaking. One of the unique advantages of these webs is that they can be made on conventional paper machines with modifications to avoid compression until the webs are at least 80 fi dry.

Thus, the primary object and advantage of the invention is to provide unique, soft, absorbent, creped, fibrous webs to accomplish.

Another object and advantage of the invention is to make it possible that such webs on a modified Paper making machine that operates at high speed can be manufactured.

According to the invention is a method of making a soft, absorbent, creped, fibrous sheet material created showing the steps of mixing

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contains a fiber entry from lignocellulosic lasers, an elastomeric binding material and water, one Web is formed from the fiber entry, in which the fiber entry is introduced into a drainage zone in which they at least touches a perforated support surface that allows water to be removed therefrom, additional water to be removed Water from the web without mechanical compression until it is at least 80 # dry, then the web adhering to a crepe surface and the removal of the web from the said surface with a crepe blade.

The present invention thus provides a soft, absorbent, creped, fibrous web formed by deposition from an aqueous slurry. The web contains randomly arranged, contacting lignocellulosic fibers and an elastomeric binding material at substantially uniformly distributed points of contact between the fibers, generally through the web, to impart structural integrity to the web. The web is characterized as having a basis weight of about 4.54 kg to about 13.6 kg per 261552Q cm ² (10 to about 30 pounds per 2880 ft ² ), a TEA to stiffness ratio greater than 1.50 χ 10 and an average calculated density due to its thickness without load of less than 0.300 g per cubic centimeter. In some cases, the web is formed from fibers that have been treated with a debonding agent to reduce their natural interfiber bonding capacity. Some embodiments of the web contain additional amounts of elastomeric binding material in a predetermined pattern to create higher strength web segments that are spaced from one another by lower strength web segments. More preferred embodiments of the fibrous sheet of the invention have a TEA-to-stiffness ratio, which is greater than 2.0 χ 10th

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The invention is also a method of forming the soft, absorbent, creped, fibrous web or sheet material described above. According to the method, a fiber insert made of lignocellulo-acaca fibers, an elastomeric binding material and water is mixed. A web is formed from the fiber input by introducing the fiber input into a drainage z one in which it touches at least one perforated support surface that allows water to be removed therefrom. Additional water is removed from the web without using mechanical compression until the web is at least 80 fi dry. The web is then adhered to a creping surface and removed therefrom by a creping blade. In some implementations, the web is adhered to the crepe surface with an adhesive. The method also includes, in some cases, the steps of applying an adhesive to selected areas of the web, e.g., by printing, and pressing the web into engagement with the creping surface so that only selected areas of the web are adhered to the creping surface.

The invention is described below, for example, in more detail with reference to the drawings, in which are:

1 is a side elevational view of one form of apparatus for forming the fibrous web in accordance with the method of FIG the invention,

Figure 2 is a side elevational view of part of one form of device to carry out one form of the method according to the invention,

Figure 3 is a side elevational view of part of an alternative Device form for carrying out one form of the method according to the invention,

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Fig. 4 is a graphical representation showing the manner

in which the dryness of a web when it is pressed is the caliber of the web after it is pressed causes

Fig. 5 is a photomicrograph with a 75 times linear Enlargement, of a cross-section of a type of prior web as described in Example 1 and which has a drawn outline above it according to the method used for determining its calculated density is described,

6 is a photomicrograph at 75 times linear magnification of a cross section of another type earlier track, as described in Example 1 and with an outline drawn over it according to the described method for determining its calculated density,

7 is a photomicrograph with 75 times linear magnification of a cross section of a web after Invention formed as described in Example 1 and with one drawn over it Outline according to the method described to determine its calculated density, and

8 is a photomicrograph at 75 times linear magnification of a cross section of a web after Invention which is shaped as described in Example 2 and which has an outline drawn over it according to the method described for determining its calculated density.

Figure 1 shows a type of papermaking machine capable of producing the soft, absorbent, fibrous sheet materials of the present invention in accordance with the method of the invention.

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The papermaking machine has a material distribution device associated therewith and is generally associated with the Numeral 10 "denotes an aqueous papermaking mousse or to deliver fiber input to a Fourdrinier wire 16. The material distribution facility contains a tapered ear distributor or head piece 11 with a source not shown an aqueous papermaking sludge or laser-in A number of branch pipes or side pieces 12 connect the tapered manifold 11 with a mixing chamber 13 'formed by generally parallel upper and lower walls 14 and 15, respectively. That Material distribution system 10 may be similar to that disclosed in U.S. Patent 3,298,905, issued Jan. 17 1967 to AC Spengos et al. The Foudrinier sieve 16 is transported over a suction chest roll 17, as well as over a plurality of table rolls 18, after which it is all around a wire reversing roller 20 runs and is guided back to the suction breast roller 17 by three guide rollers 21, 22 and 23 is. The entirety of the wire 16 and its support rollers is driven by a drive device, not shown driven, which is connected to the wire reversing roller 20.

One or more vacuum boxes, water fans, or other drainage or formation aids Devices (none of which are shown in fig. 1) can be used in conjunction with the foudrinier screen 16, furthermore, the shape of the papermaking machine can vary widely from that previously described without affecting the present invention. It is important, however, that this is done on the foudrinier sieve 16 formed web is kept free of any mechanical compression or compaction until at least

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$ 80 > is dry, for reasons that will be discussed below

At this point the spell is essentially shaped free of any compaction or mechanical compression from the top surface of the foudrinier screen 16 transfer the surface of a perforated drying fabric 24, which may be a woven sheet material, such as it is made from wire or other filamentary materials, or on perforated or punched holes Base. The drying fabric 24 is brought past a point which closely adjoins the part of the Foudriniersiebes 16 between the wire reversing roller 20 and the first Guide roller 22 is running. This involves a rotating suction take-up roller 25 or a stationary suction take-up shoe and transmission thereto can be assisted, if desired, by steam or Air jet coming from a collecting tube 26, as indicated in dashed lines in Fig. 1, which opposite the Foudriniersieb 16 and the suction take-up roller 25 is arranged. The drying fabric 24, which the Web carries, moves from the suction take-up roll into a drying device, indicated generally by the reference numeral 27, and is then transported over guide rolls 28 and 30 and around a pressure roll 31, which the BaTm into engagement with the surface of a Crepe drum 32 presses. One or more vacuum boxes, not shown, can be arranged behind the drying fabric 24 be which the take-up roller 25 pounds to remove additional entrained water from the web without compression to remove. The drying fabric 24 advances to another guide roller 33 and then returns to the transfer point adjoining the take-up roller 25.

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The drying device 27 may comprise any means for drying the web at a point where it has a moisture content of less than 20 weight percent that is, so that it is dry over $ 80>. It is important that no mechanical compression or densification of the web occurs before it has reached this drying level and therefore traditional Yankee drying techniques, in which the paper web is pressed tightly against the surface of a steam heated Lankeet drying drum, must be avoided if it has a moisture content above $ 20 > · However, it has various other techniques are used for drying the web, including radiant heat lamps, tunnel dryer or Transpirationstrockner, preferably wherein heated air is passed through the web. FIG. 1 illustrates a typical form of a transpiration dryer in which air is passed from a hood 34 through the web and through the drying fabric 24 as well as through the drum 35, which supports both and from there from inside the drum 35 through another hood 36 Will get removed. A typical form of such a drying apparatus is shown in U.S. Patent No. 3,432,936 dated March 18, 1969, issued to RI CoIe et al.

Since the web attached to the surface of the crepe drum 32 is over 80 i> dry, it is often necessary to apply a crepe adhesive, e.g., starch, to the web surface or the crepe drum 32 by means of an elongated spray device 37, as shown in broken lines in 1 is shown. This is especially true where the sheet has dried to a height of 90 degrees or above because there is insufficient moisture in the web at this point for it to reach the crepe drum

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to glue and to allow her to be covered with crepe of it. A crepe blade 38 is on the opposite Side of the creping drum 32 from the pressure roller 31 and is used to the web of the crepe drum 32 to remove. The Pig. Figures 2 and 3 illustrate alternative methods of applying adhesive to the Bshn to glue it to the crepe drum 32. Thus, FIG. 2 shows a glue application roller 40, which picks up glue from a container 41 and applies it to the surface of the web immediately before the web Crepe drum 32 touches, transfers. Fig. 3 shows an application roller 42 drawing glue from a container picks up and attaches it directly to the crepe drum 32, after which the web is pressed into contact therewith and adhered.

Each of the embodiments shown in Figures 2 and 3 are particularly useful in the practice of the method of the invention where only predetermined parts of the web are adhered to the crepe surface to provide a differential or Patterned creping of the web to increase bulk, softness and strength. Where, for example If additional strength is to be incorporated into the web, the adhesive that is printed on the web contains is, as in Fig. 2, or on the crepe drum, as in Fig. 3 »an elastomeric binding material, which further Interfiber connection carries out in the parts of the web which it is applied. The advantages of this are shown below.

As previously stated, the method of the present invention includes a number of steps that differ result in the formation of the new sheet materials of the invention. The process includes the mixing of a fiber

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loads of lignocellulosic fibers, an elastomeric binding material and water. A web is then formed from the furnish according to any number of different techniques, most of which are standard techniques used in papermaking. The web is then subjected to the treatment to remove water therefrom without mechanically compressing the web. It is important that enough water be removed from the web in this manner so that it is at least 80 % dry before it is mechanically compressed. The web is then adhered to the creping surface and creped from the surface with a creping blade.

The mixing step is normally carried out in a head box preceding the flow distribution equipment used on the papermaking machine. The parsers are in the entry largely contain relatively short fibers, ie, those mm a length of less than 1.6 have (1 / 4- ^11), and the predominantly short and are substantially all of the fibers are lignocellulosic fibers, ie, those derived from any natural wood fiber sources, such as wood pulp, to form hydrogen binders of the type associated with papermaking.

The elastomeric binding materials that can be used in the present invention are basically any materials that are capable of at least 75 % elongation when broken. Such materials should generally have an original Young's modulus by extension that is less than 1757.5 kg / cm (25,000 psi).

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! Typical materials can be of the butadiene-acrylonitrile type his or other natural or synthetic gummilatixes or dispersions of the same with elastomeric properties, such as butadiene-styrene, neoprene, Acrylic copolymers, polyvinyl chloride, vinyl copolymers, or nylon. Elastomeric properties can be achieved through the Addition of suitable plasticizers to polymers, such as polyvinyl alcohol or carboxy methyl cellulose can be obtained.

Although webs can be formed according to the present invention with virt parts in a wide range of basis weights, namely sanitary for purposes of forming paper products, it is preferred that the basis weight (10 ft to about 50 pounds per Hies 2880 ²⁾ of about 4 , 54 kg to about 15.6 kg per ream of 26? Stf20 cm ^2. Sheets or sheet products in this particular basis weight range are most useful in the method of the present invention as they find extensive use in areas where softness and bulk are important. For example, where the product is a wiper, both softness and bulk are important, as are liquid absorption and strength. This basis weight range is one where it is very difficult to give a product the combination of properties that can be achieved by the present invention. As indicated above, the web can be formed by any technique which involves the deposition and drainage of the fibrous sludge on a perforated condenser such as a boudrinier screen, and of course the rate of formation of such webs can be several hundred feet per minute vary to over 5,000 feet per minute.

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The steps of the process in which the web is formed and is partially dried without being compressed in any way, are for the invention for Achieving the formation of a web is extremely important, having the desired characteristics of great bulk and softness and has unusually low density. It is through extensive experiments that it would be found that if an orbit passed through Depositing a fibrous sludge on a foudrinier sieve is formed and dried to at least 80 # dryness, before being subjected to any mechanical compression If, for example, between two surfaces in a felt or roller clamp, the subsequent compression is only minimal Effect on the following properties such as mass or caliber has, if not such a compression sufficiently hard is to cause the breaking of fasteners or the chemical transformation of the lignocellulosic material, as it often occurs in a stamping or calender clamp. So after the web will use the water removal techniques has been subjected to make them $ 80 or more dry, their eventual caliber is not appreciable causes typical pressing processes, such as those in paper-making machines in pressure nips and in the nip between the platen and the Yankee dryer.

Figure 4 of the drawings graphically shows the experimental results in this area. For testing purposes, a fiber furnish composed of 50 # Western softwood sulfite pulp and 50 # Southern gum kraft pulp was formed into handsheets having a basis weight of 4.54 kg (10 pounds) per ream of 26 * 5520 cm ² .

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One of the handsheets was not subjected to any pressure and was dried. Its caliber was measured and found at the level shown in broken line on the graph. Additional handsheets were dried to give heights of web dryness as indicated by the fiducial points on the graph. They were then subjected to pressure between surfaces at a height of 2.819 cm (40 psig). The samples were then dried to 95 Ψ> dry and their caliber was measured.

From the resultant graph line which accompanies this experimellen points, it is seen that, is dry to the web at least 80 i ", their caliber is substantially reduced, it wcim is pressed, under that of an unpressed sheet. This is known to result in a largely increased number of τοη inter fiber connections, which, as previously mentioned, is undesirable. There is also an increased web density, which means less softness

The caliber and basis weight values reported herein were determined by the following methods; The basic weight was measured in accordance with TAPPI Standard T 410-05-61. The caliber or thickness of a sheet was made with Federal Micrometer Gauge, Model No. D 815 in accordance measured with TAPPI Standard T-411-44. A face of

ρ ρ

(1 ") 6.452 cm (0.5 psi pressure) was used when 12.7 kg (28 pounds) per ream of sheet were tested instead

the 0.25 inch ² face (pressure from 7-9 psi)

0.49 kg / cm ² to 0.63 kg / cm ² .

The caliber is given in 1/1000 "(mils).

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The web at this point has less hydrogen binder than would normally be present in a web that did has the same basis weight but which has been subjected to at least 80 # compression prior to the dryness. This small amount of hydrogen binders gives the web an unusual softness and compressibility and natural the web has greater mass (lower density) due to the fact that it was not compressed when it was compressed Condition was damp or soaked.

A more preferred embodiment of the present invention results from an even further reduction in number of hydrogen binders of the type used between fibers in papermaking. It is well known that such binders are typically quite hard and inelastic, and unfortunately these give the resultant Bahn some general properties. By treating the fibers from which the web is formed with a chemical Delivery devices, e.g. by adding such a delivery device (debonder) to the fibrous sludge or slurry in the head box, the number of joints becomes longitudinal of the individual pasers is reduced, so that the pasers are less receptive to interfiber connection through hydrogen bonding are. The debinding agents that can be used for this purpose include, for example, the cationic debinding agents, as disclosed in U.S. Patent No. 3,395,708, which issued to Hervey et al on August 6, 1968; Substances in the class of long-chain cationic surfactants, preferably having at least 12 carbon atoms in at least one alkyl chain, such as quaternary amine salts, monofatty alkyl tertiary amine salts, primary amine salts and unsaturated fatty alkyl amine salts; the cation-active tertiary amine oxides described in US Pat. 2 432 126 of Disclosed December 9, 1947 to Schlosser et al; and the

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cationic amino compositions disclosed in U.S. Patent 2,432,127 issued December 9, 1947 to Schlosser et al are.

The elastomeric binding material, which is also the fibrous Slurry added to the head box replaces its binding capacity for those of the hydrogen binder, which is prevented by the binder and ensures sufficient Interfiber link to ensure the railway's structural integrity granted. Furthermore, the bonds formed by such elastomeric binding materials are quite soft and compliant and impart further softness to the web without reducing its absorbency or its mass, i. e. without increasing their density.

As mentioned earlier, those in the Pig. The devices shown in FIGS. 2 and 3 can be used to apply adhesive to the web or to the creping surface to increase the bond of the web to the creping surface to promote better dry crepe and a softer product. This 1st particularly important where the moisture content of the web which is attached to the Kreppierungsoberfläche is less than 10 i ", for example, when the web 90 i> is dry. The creping adhesive replaces the lack of moisture commonly used to attach the web to the dryer surface.

In certain more preferred embodiments of the invention, the devices shown in Figs. 2 and 3 are used to to print binding material in predetermined patterns on the web or alternatively on the crepe surface, to selectively adhere the web to the creping surface.

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However, in addition to the unique creping effects, which are achieved by this manner have been found desirable to be either an elastomeric To use binding material as the adhesive between the web and the creping surface, or elastomeric Add binding material to the adhesive so that when bs finally follow the web through one of the devices the Mg. 2 and 3 is attached, it provides additional strength to the web. That is, the elastomeric binding material, which is attached in this manner creates areas of greater interfiber connection and therefore areas of greater web strength than adjacent ones to which no additional adhesive has been applied beyond that attached to the pasers themselves in the head box is.

The pattern of binding material which is applied to the web can be of any shape which leaves a substantial portion of the surface of the web free of extra amounts of binding material other than that used during web formation. Most preferably, the pattern contains less than about $ 35> of the total surface area of the web to at least leave about 65 or more of the surfaces of the web of additional binding material when printed. In this manner, any of the patterns disclosed by U.S. Patents 3,047,444; 3 009 822j 3 059 313 and 3 009 823 can advantageously be used for the rollers 40 or 42, which in this case comprise engraved rollers. Any migration of binding material occurs after printing. In this way the binding material penetrates at least partially through the web and in all directions in the plane of the web. However, the migration in all directions in the plane of the railway is minimal,

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to leave areas that contain a substantial portion of the web free of any additional binding material, which is other than that attached by the head boxes, and for the purposes that appear below.

It has been found particularly desirable that the additional To attach binding material in a reticulated pattern so that the additional binding material is a reticulated web of forms additional strength across the web. Thus it is well known that papermaking fibers are generally one Less than about 6.3 mm (1/4 ") in length and typically less than about 1.6 mm predominant fiber length have in length. Therefore, it is when the sheet is given additional strength in addition to that in the by a binding material Headbox added, as in this embodiment of the present invention, it is important that a uninterrupted interconnection of at least some of the fibers by the additional binding material throughout the web is present through it. If the pattern of additional binding material take the form of parallel lines, bars or other Has forms of discrete surfaces, the web will lack the added strength beyond that desired provided by the binding material added to the head box, if not separate areas spaced apart by stretches that are less or typically less than the average fiber lengths than about 1.6mm. However, where the pattern of adhesive in the form is reticulated or reticulated, the interconnected create Lines of binding material apply a network of strength, even where essential areas in some cases much larger than 1.6 mm, in each sighting between the lines of binding material application are determined, such as web parts that one have less amount of interfiber bond.

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The creping drum 32 may in some cases be heated Pressure vessel, such as a Yankee dryer, or in other cases can have a narrower roller and unheated to be available. It is characterized by an outer smooth polished surface on which the binding material, which is attached to the web, adheres. The importance of heating depends on both the characteristics of the particular used binding material and the moisture level in the Train off. Thus the binding material may require drying or hardening by heating, in which case the crepe drum 32 may be provided with conventional means to accomplish this. Or else, the moisture level the web fed to the creping drum 32 can be higher than that ultimately desired and the crepe drum 32 may be heated to remove some of this moisture evaporate.

In each of the embodiments shown in FIGS. 2 and 3, the Web is transported on the surface of crepe drum 32 for a distance and then away from it by the action of a crepe doctor blade 38 The doctor blade 38 performs a customary creping effect on the additionally connected parts of the Web off, i.e., it gives a series of fine fold lines to portions of the web that are adhered to the crepe surface 32 are. However, since in this case the web is only adhered to the crepe surface 32 in a pattern which either has a reticulate shape or contains a plurality of spaced apart discrete areas causes the creping blade 38 the lesser bound web parts that are not attached to the crepe drum 32 to puff up and bend open, to form molded sheet parts that have excellent softness characteristics.

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The binding material used in the embodiment of the invention described above must be capable of various punctures, one being the ability to bind fibers together in the web, the other being the ability to do so in addition bonded parts of the web to the surface of the crepe drum 32. In general, any material which has both of these abilities to be used as the binding material when the material is dried or hardened ' can be to sit down. Among the binders capable of performing these two functions and the can be used successfully are acrylic latex rubber emulsions, useful on an unheated crepe surface; Emulsions of resins such as acrylates, vinyl acetates, vinyl chlorides and methacrylates, all of which are useful on a heated crepe surface; also water-soluble resins, such as carboxymethyl cellulose, polyvinyl alcohol and polyacrylamides. In other cases, however, the binding material may be a Mixture of different substances, one of which has the ability to carry out the interfiber connection while the other is useful to prevent the web from sticking to the crepe surface to generate a laugh. However, in each case the materials are preferably used as an integral blend of the same areas of the web applied. Such materials can include any of the materials listed above are mixed with a low molecular weight starch such as dextrin or a low molecular weight polymer, such as arboxymethyl cellulose or polyvinyl alcohol. Of course, compatible wet strength additions may be used with any of the foregoing materials to provide additional wet strength strength to the resulting sheet material.

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It has been found desirable to apply the binding material to the surface of the crepe drum 32 just prior to the Covering this surface with the web, particularly where the binding material is volatile or volatile Contains ingredients that set or cure rapidly, especially at elevated temperatures in the event that the Crepe drum 32 is heated. This ensures that the binding material will penetrate the web to the desired thickness and that portions of the web are tacked to the dryer before the binding material cures and loses its tackiness,

The sheet materials of the present invention resulting from the treatment with an elastomeric binding material of webs formed by deposition from an aqueous slurry of lasers, water, and preferably a debinding agent, are of any other prior art in properties such as softness and wipeability of sheet material which so formed was not subjected to such treatment. These properties can be characterized in many different ways when applied to sheet material used in sanitary paper products such as tissues, towels and the like. This is due to the fact that softness and wipeability are largely subjective impressions received from the treatment of the sheet material and which are an estimate of the combination of thickness or mass, density, resistance to bending and compression, and other physical properties, which are accessible to ^{E 1 UhI observation.}

However, for purposes of measuring the acceptability of these materials of the present invention for use in the aforementioned sanitary paper products from that

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general point of view of softness two different properties has been found to be a basis for an accurate distinction of such materials from those in combination the previous technique. These properties are (1.) the TEA to rigidity ratio of the sheet material and (2.) the mean calculated density through the thickness of the sheet material under no load, these properties, the desired areas therefor and the procedures and techniques, as well as the determination thereof, are described in detail herein, to explain the invention, and to allow others to choose its scope with reference to such sheet materials to determine.

The TEA to stiffness ratio is obtained by first Measurement of the TEA (tensile energy absorption) jH5k «strain energy absorption of a given sample of sheet material in accordance with the TAPPI test, T 494 su-64, both in the machine direction (M.D.) and the cross machine direction (CD.) In kilometers per square meter, with the exception that a jaw distance of 2 "instead of 8", which is through TAPPI is recommended because of the particular nature of the product, some of which have perforation lines, which must be avoided.

This test method is not a TAPPI standard but is suggested by TAPPI as the most suitable method. The stiffness of the product is then measured by subjecting the sample to the test, TAPPI Stanaard test T is set 451m -60 in, both in the machine direction mnd in cross-machine direction to the effective overhanging length (critical length) to determine , which is labeled as "L" in centimeters. The stiffness of the product is proportional

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209353/0908

- ■ 27 -

the cube of effective overhanging length and is therefore expressed herein as L.

Briefly described, the TEA of a product is obtained by clamping a 2.54-0.01 cm wide sample into two spaced sets of jaws when they are 5 * 08 cm apart, with any noticeable slack pulled out before the Strip is clamped · Tension is placed on the sample by moving the jaws further apart at a constant rate of 2.54-0.02 cm / min, the elongation with an accuracy of ί 2 i> the real value and the load is recorded in pounds or kilograms with an accuracy of - $ 0.5 up to the break of the sample. The area under the strain extension curve is then framed by a planimeter or integrator with an accuracy of -2 #. The TEA is then calculated using the equation

TEA = 100A with units of kilometers per square LW meter, where are:

A = area under the load extension curve in kilogram-centimeters

L = original span between the clamping lines in Centimeters,

W = original width of the sample in centimeters.

The stiffness of a product is obtained with a Clark softness tester, by cutting the ends of a 15-50 mm wide specimen with parallel edges and normal length between the jaws or rollers are set which includes a clamp attached to a rotatable spindle. The spindle can

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rotated about a horizontal axis parallel to the longitudinal axis of the jaws or rollers and perpendicular to the longitudinal axis of the paper strip. The overhanging length of the sample will be set by re-adjusting the jaws or turning the rollers until when the spindle slowly goes back and forward over Is rotated 90 °, the sample just falls over at each of the endpoints of the rotation. The overhanging or critical length L. is then measured from the line where the edges of the jaws or rollers grip the sample at the end of the strip. For purposes of determining the products of the present invention, the stiffness is indicated by the L cube.

In using the above tests for TEA and stiffness to establish a ratio which will determine a desired property of a fibrous product of the invention, samples are taken in both the machine direction (MD) and the cross machine direction (CD.) For each test. Preferably, various tests are run on each and the results are averaged to eliminate errors due to the measurement or formation. The resulting values are then combined in a ratio as follows: The TEA-to-stiffness ratio is = TEA / ^ - _ΰ s χ TEAz _{0 D} \

Ί? (MD) χ Ί? (CD.)

The mean calculated density through the thickness of the sheet material under no load is determined by the following procedure. A sample of the The product is oven-dried to eliminate any moisture in it. The dried sample is put into a small container and slowly immersed in a solution of butyl methacrylate monomer at atmospheric pressure, which

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in it a small amount of beniyl peroxide as a catalyst contains. The container and submerged sample are then placed in an oven that has an internal temperature of 55 ° for a period of about 16 hours to cause the monomer to polymerize. It appears a small amount of volumetric shrinkage which is insignificant because it is constant for each sample. It will Cross-sections cut from the resulting embedded sample using a microtome and with the Sections 10-12 microns thick. Each section is placed on a glass sled and covered with mineral oil and covered by a glass lid. The section of the sample is now photographed by transmitting light through a microscope, which has a 24mm objective lens and an eye part of 12.5X The expansion of the bellows is 50 cm. The resulting linear magnification is 75 and the enlarged image is in printed in a 5 "x 7" format.

The resulting photomicrograph is mounted on a board and a transparent paper is placed over it. The outer line of the resulting cross-section shown in the photomicrograph is now drawn on the tracing paper, care being taken to follow the base curves and corrugations of the cross-sectional outer line to an extent sufficient to allow at least 95 ^c ß> or on the inside of the outer line to get more of the cross-sectional area that contains any stray fibers. Certain stray fibers that deviate from the outline should be left on the outside of the surface in order to obtain accurate tightness values.

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2 0 9853/0908

A planimeter is then used to measure the area within the inside edge of the line which is the cross-sectional outside line determined in square inches. Different photographs of each sample are preferably used, and they become different Cross-sectional area measurements are taken, the results being the average, to obtain a reliable cross-sectional area to obtain.

The actual thickness of the sample was obtained by dividing the area by the length of the cross-section, which is marked with is provided with an outline and by the linear magnification of 75. The calculated density under no load in grams per cubic centimeter was obtained by the equation:

Calculated density g / cc = basic weight g / m

actual thickness (in) χ 2.54 cm χ

10,000 cm

where the basis weight is that of the original sheet material from which the sample was taken.

All of the sheet materials of this improved form of the invention contain a web of randomly arranged lignocellulosic ones Fibers and elastomeric binding material, such as the one previously mentioned, at some of the points of contact between said fibers to provide structural integrity to the sheet material or web. The tignocellulosic Fibers can be any of the wood pulp fibers normally used in papermaking. In Depending on the particularly fine pattern in which the binding material is applied to the web and the extent of the Migration of this material through the web can form bonded web segments, the elastomeric binding material, which in the

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- 51 -

Distance from unbound ban segments are arranged. In a particular embodiment, the binding material in the web is in a continuous predetermined reticulate manner Pattern present which is an interrupted, predetermined intermittent pattern of separate unbonded web segments certainly.

Preferably, the fibers are coated with a binder treated in an amount sufficient to increase their interfiber capacity so that a flat sheet consisting essentially of such fibers has a breaking length of less than 800 meters and preferably less than 700 meters as determined by the method set forth in the TAPPI Hevised Tentative Standard T 220 m-60 disclosed. In this Process is a pulp sheet, which has a basis weight (r) in 0 grams per square meter (on a moisture-free Basis) measured to determine its tensile breaking load (p) in kilograms measured on a 15 mm strip. The fracture length in meters is calculated from the equation:

Fracture length = 200,000 ρ
3 r

and is equivalent to the length in meters of a uniformly wide strip of paper that when held at one end (e.g. freely hung a spool of this paper by its strip end), just causing the strip to be underneath to break its own weight.

The following examples comparatively illustrate the difference between the sheet materials of the present invention and the common sheet materials used in the past.

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This difference is clearly evident from the properties measured according to the above methods, and to a large extent from the use of elastomeric binding materials therein with a reduced amount of Interfiber binder due to natural connections before drying the web. However, some specific listing of details should be included should not be construed as a limitation within the scope of the invention.

Example I.

As an explanation of the prior art, a first web was formed from a fiber insert consisting of water and the the following conventional papermaking pulps.

20 ° / o Softwood Bleached force

20 f> Softwood Bleached Sulphite

40 for Hard Wood Bleached force

20 ° β> mechanical fiber

The web was formed on a conventional paper making machine of the Fo ^ rdrini'erart and was transferred to the surface of a Yankee dryer by a felt web. The web was creped from the Yankee dryer, as dry fi about 65, that is, as it contained only about 35 7 ° moisture by weight. The web was further dried in an after-dryer section in the form of heated drums until it was more than about 92 % dry. The resulting sheet material was one typically used in sanitary paper products, such as wet creped bathroom fabrics, and had the following general properties:

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G-round weight

Base weight 20.8 gms / M ² - 12.3 lbs / 2880 ft ²

Bulk 0.081 in / 24 sheets (Federal Bulker)

tension

Tensile (MD) 12.8 oz / in (TAPPI STANDARD, T220 m-60)

strain

Stretch (MD) 7.9 # (TAPPI STANDARD, T 220 m-60) TEA (MD) 0.993 Kg - Μ / Μ ² (TAPPI TEST, T494 su-64)

tension

Tensile (DD) 5.3 oz / in (TAPPI STANDARD, T 220 m-60)

strain

Stretch (OD) 3.3 f> (TAPPI STANDARD, T220 m-60) TEA (CD) 0.189 Kg - M / M ² (TAPPI Test, T494 su-64) Lo (MD) 5.5 cm (Critical length - TAPPI STANDARD, T -451 m-66)

Lo (CD) 4.5 cm (Critical length - TAPPI STANDARD, T-451 m-66)

This first web was subjected to the tests previously described and found to have a TEA to 3 stiffness ratio of 0.12 10 " ⁴ and a mean calculated density through the thickness of the web under no load of 0.441 A typical cross-section of this first web, photographed at a linear magnification of 75, as described above for determining the mean calculated density, is shown in Figure 5. The actual appearance of the web shows the close-packed arrangement of the Fibers and the relative hardness of the sheet even after creping has occurred An outline of the cross-section has also been drawn on the photograph to illustrate the manner in which FIG

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which this for the purpose of determining the area and the Average diameter of the cross-section is executed.

As another illustration of the prior art, a second web was formed from a fiber insert made up of water and the following papermaking pulps.

30 i> Softwood Bleached Kraft Softwood Bleached Kraft

25 fi Softwood Bleached Sulphite Softwood Bleached Sulphite

35 fi Hardwood Bleached Kraft Hardwood Bleached Kraft

10 yes Mechanical laser Mechanical Fiber

The web was formed on a conventional Fourdrinier type papermaking machine and was fed through a Transfer felt belts to the surface of a Yankee dryer.

The sheet was creped from the Yankee dryer when she i "was dry, that is, as it contained about 94 just 6 i 'moisture by weight. The resulting crepe material was one typically used in sanitary paper products, such as dry creped bathroom fabrics, and had the following general properties:

Basic weight

Base Weight 9.6 lbs / 2880 ft ²

Dimensions

Bulk 0.086 in / 24 sheets (Federal Bulker)

209853/0908

tension

Tensile (MD) 12.6 oz / in (TAEPI STAETDAEI), T220 m-60)

strain

Stretch (MD) 1? .5 i> (TAPPI STAUDAIiD, T220 m-60) TEA (MD) 1.29 Kg - M / M ² (TAPP! TEST, T494 su-64)

tension

Tensile (OD) 2.4 oz / in (TAPPI STAIiDAED, T220 m-60)

strain

Stretch (CD) 5.6 $ (TAPPI STANDARD, T220 m-60) TEA (OD) 0.20 kg - M / M ² (TAPPI TEST, T494 su-64)

Lo (MD) 3.8 cm (Critical length - TAPPI STAUDABD, T-451

m - 60)

Lo (CD) 4.5 cm (Critical length - TAPPI STANDARD ',

T-451 m - 60)

This second track was used in the experiments previously described and found to calculate a TEA to stiffness ratio of 0.527 x 10 and an average Density through the thickness of the web under no load of 0.466 grams per cubic centimeter. A typical cross-section of this second web, which was photographed with a linear magnification of 75 as described, to the Determining the mean calculated density is shown in Mg. 6. The real appearance of the leaf shows the tightly packed one Arrangement of the fibers and the relative hardness of the sheet even after creping has occurred. An outline The cross-section has also been drawn on the photograph to illustrate the manner in which this is done the determination of the area and the average diameter of the cross-section is carried out.

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- 56 -

By. Comparison as an explanation of the present In accordance with the invention, a third web was formed from an uncleaned fiber insert, that of water and the following conventional papermaking pulps consisted of:

80 # Softwood Bleached Kraft Softwood Bleached Kraft

20 i ° Hardwood Bleached Kraft Hardwood Bleached Kraft

The following chemicals were added to the papermaking entry as a weight percentage of the wood pulp:

0.7 9 »Quaker 2000, debinding agent produced

a debonding agent manufactured by
by Quaker Chemical Company, Conshohocken,

Pennsylvania, used to reduce interfiber bond capacity Pennsylvania, used to reduce interfiber bonding capacity,

0.085 fo S-243 Amine -.a cationic polyelectrolyte used for beater deposition of anionic materials, and

5.0 io Ehoplex P 339 - an anionic acrylic latex used as an elastomeric bonding material.

The web was formed on a conventional Fourdrinier type papermaking machine and attached to a synthetic one Twill fabric of 72 χ 60 meshes transferred by means of a suction shoe at a point where the web connects to a stretch of the Pourdriniersiebes is transported, which runs between two support rollers. While they are being promoted on the fabric is, the web was subjected to a vacuum, which on

209853/0908

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the underside of the tissue is applied at 25.4 cm - 28 cm (10 to 11 inches) of mercury for a period of 15 milliseconds. This reduced the moisture content of the wet web to approximately $ 70 by weight of the wet web. The web was further dried on the web by passing heated air at 127 ° C (260 ° F) through the web while it was conveyed on the web through a tunnel dryer. The tunnel dryer had sufficient heat capacity to reduce the moisture content of the web to less than $ 10 by weight of the wet web that the web was now over $ 90> dry. The conveyed web was then transferred from the fabric to the surface of a 50.8 cm (20 inch) diameter creping dryer by means of a nip formed against the dryer surface by a 127 mm (5 inch) diameter elastomeric roller having a neoprene cover of dam 12.7 mm (1/2 inch) thick, and a hardness of 55 Shore A.

To ensure complete transfer and uniform adhesion of the web to the creping dryer surface, a 1.5 $ solution of Peter Cooper TG 220 creping adhesive was sprayed into the nip between the web and the creping dryer surface. The amount of adhesive that was present in the web after spraying is about 0.1 # by weight of the web. The nip pressure between the elastomeric roll and the creping dryer was maintained at 4.22 kg / cm (60 psi). The crepe dryer contained electrical heating coils of sufficient capacity to maintain a surface temperature of 93 ° C (200 ° F), which is sufficient drying to reduce the moisture content of the sprayed web to about 6 <fo by weight on the crepe blade at a crepe dryer speed of 9 »15 m (30 feet)

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- 58 -

reduce in the minute. The web was creped from the surface of the drying drum by a conventional creping blade set at the point of contact at a creping angle of 5 ° above the radial line. The creped web or sheet material was taken up at a rate of 7.95 m (26 feet) per minute, which in a perspective drawing of the web in the machine direction shows 15 ^c ß> , ie the formation of 15 $> crepe in the resulting sheet material. The track had the following general characteristics:

Basic weight

Base Weight 22.5 lbs / 2880 ft ²

Bulk .252 "/ 24 sheets (Federal Bulker)

tension

Tensile (MD) 17.0 oz / in (TAPPI STANDARD, T 220 m-60)

strain

Stretch (MD) 18.6? 6 (TAPPI STANDARD, T 220 m-60) TEA (MD) 1.286 Kg - M / M ² (TAPPI TEST, T494 su-64)

tension

Tensile (CD) 5.4 oz / in (TAPPI STANDARD, T220 m-60)

strain

Stretch (CD) 10.5 # (TAPPI STANDARD, T220 m-60) TEA (CD) Ο »557 Kg - M / M ² (TAPP! TEST, T494 su-64)

Lo (MD) 5.8 cm (Critical length - TAPPI STANDARD, T-451 m-60)

Lo (CD) 4.26 cm (Critical length - TAPPI STANDARD, T-451 m-60)

Elastomeric binder content through Any lysis 4.0 $>.

- 59 -209853/0908

Biwatra sheet material was used in the experiments described previously and had a TEA to stiffness ratio of 1.55 x 10 and a mean calculated density through the thickness of the sheet under no load of 0.180 grams per cubic centimeter. Typical cross-section of this third web, the Photographed at a linear magnification of 75 as previously described to determine the mean calculated density, is shown in FIG. It is easy to see from the appearance of this sheet that the ridges are loosely arranged are to provide low density and high bulk, which are both key factors in the softness of the web. An outline of the cross-section has also been drawn on the photograph to indicate the way in which this is done for the purpose of determining the area and the average thickness of the cross-section.

Example II

A fourth web was formed from an uncleaned fiber furnish consisting of water and the following conventional ones Papermaking pulps consisted of:

80 i> softwood bleached Kraft
Softwood Bleached Kraft

20 ° jo hardwood bleached force
Hardwood Bleached Kraft

The following chemicals were added to the papermaking charge as a percentage by weight of wood pulp.

0.5 $> Quaker 2000, delivery made with t el

a debonding agent manufactured

by Quaker Chemical Company, Conshohocken, Pennsylvania, used to increase inter-fiber linkage capacity

reduce used to reduce interfiber bonding capacity,

209853/0908

- 40 -

0.05 i> S - 243 Amine - cationic polyelectrolyte used for racket storage of

used for beater deposition of anionic materials, and 2.0 i » Hhoplex P 339 - an anionic acrylic latex used as an

elastomeric bonding material - used as an elastomeric bonding material *

The web was formed on a conventional Fourdrinier type papermaking machine and transferred to a synthetic twill fabric of 72 × 60 mesh by means of a suction shoe at a point where the web is transported to a stretch of the Fourdrinier wire which runs between two support rollers. While it was being conveyed on the fabric, the web was subjected to a vacuum applied to the underside of the fabric at 25.4 cm - 28 cm (10-11 inches) of mercury for a period of 15 milliseconds. This reduced the moisture content of the wet web to approximately 70 % by weight of the wet web. The web was further dried on the web by passing heated air at 127 ° 0 (260 ° F) through the web while it was conveyed on the web through a tunnel dryer. The tunnel dryer had sufficient heat capacity to reduce the moisture content of the web to less than $ 10 by weight of the wet web that the web was now more than 90 ° / <> dry. The web was then conveyed through apparatus similar to those shown in FIG. So it was printed in a nip formed by a patterned engraving roller that was 12.7 cm (5 inches) in diameter and an elastomeric roller that was 12.7 cm (5 inches) in diameter and a neoprene blanket 12 , 7 mm (1/2 inch) thick with a hardness of 65 Shore A. The engraved roller had a reticulate pattern of interconnected deformed

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Hexagons, the two sides perpendicular to the machine direction and a pattern repeat length of 0.254 mm (0.040 inches) had. The vertex to vertex distance in the transverse direction was 2.032 mm (0.080 inches). The engraved lines of the Patterns were 180-190 microns wide and approximately 46 microns deep. The engraved lines of the pattern approximated 27 # of total surface area.

The binder material, which has been attached to the web through the engraved roller containing an elastomeric binder material which ia Celanese 5269 consisted of a mixture of 70 i »Calanese 6308 and 30 by weight. This binding material is an aqueous emulsion with a pesticide content of $ 45 and a viscosity of 250 centipoise at 25 ° C, as measured on a BrookfieLd RF7 viscometer spindle

3 at 20 revolutions per minute. The pressure in the print nip was averaged 7.03 kg / cm (100 psi) and the average basis weight of the sheet was increased by $ 12.0 during the print. The printed web was then attached to the surface of a 38.1 cm (15 inch) diameter cast iron creping dryer by means of the elastomeric roller previously described and with an average nip pressure of 8.79 kg / cm (125 psi). The crepe dryer was oil heated with a surface temperature of 88 ° C (190 ° F) and the drum surface speed was 6.10 m (20 t feet) per minute. When the web was pressed against the dryer the average dryness was $ 84 > and when it exited the drum the web had an average dryness of about $ 94. The web was creped from the surface of the drying drum by a conventional creping blade set at an angle of 6 ° below the radial line of the point of contact.

209853/0908 " ⁴² "

The quilted web or sheet material was wound up at a speed of 5 m (16.6 feet) per minute, resulting in a perspective in the machine direction of $ 20>, the formation ie of 20 f> crepe in the resulting sheet material. The sheet material had the following general properties:

G-round weight

Base Weight 23.5 lbs / 2880 ft ²

Bulk 0.354 in / 24 sheets (federal bulkers)

tension

Tensile (MD) 8.3 oz / ± n (TAPPI STANDARD, T220 m-60)

strain

Stretch (MD) 21.8 # (TAPPI STANDARD, T220 m-60) TEA (MD) 3.372 Kg - M / M ² (TAPPI TEST, T494 su-64)

tension

Tensile (CD) 5.8 oz / in (TAPPI STANDARD, T220 m-60)

strain

Stretch (CD) 16.4% (TAPPI STANDARD, T220 m-60) TEA (CD) 0.779 Kg - M / M ² (TAPPI TEST, T494 eu-64)

Io (MD) 3.8 cm (Critical length - TAPPI STANDARD, T-451 m-60)

Lo (CD) 4.6 cm (Critical length - TAPPI STANDARD? T-451 m-60)

Elastomeric Bonder Content by Analysis

beater addition 1.5 #
print bonding 5.5 #

The sheet material was subjected to the tests previously described and had a TEA to solubility ratio of 4.91 ι 10 and a mean calculated density by the

209853/0908

- 43 -

Thickness of the sheet he lint no load of 0.139 grams per Cubic centimeter. A typical cross-section of this third web, the one with a linear magnification of 75, as before was photographed to determine the mean calculated density is shown in FIG. It is easy it can be seen from the appearance of this sheet that the fibers are loosely arranged to allow for low density and large mass to care, which are both key factors in the softness of the web. An outline of the cross section is also on The photograph has been drawn to indicate the manner in which it is used for the purpose of determining the area and the - the average thickness of the cross-section is carried out. The results for the four webs in Examples 1 and 2 are listed in Table I for comparison purposes.

Table I.

Web TEA to Stiffness Ratio Calculated Density TEA-To-Stiffness Ratio Calculated Density

First train.

First Web 0.12 χ 10 ~ ⁴ 0.441 gms / cc

Second lane _A

Second Web 0.527 x 10 "" * 0.466 gms / cc

Third track.

Third Web 1.55 x 10 "" * 0.180 gms / cc

Fourth lane _A.

Fourth Web 4.91 x 10 "" ⁴ 0.139 gms / cc

From the above data it can be seen that a remarkable Product improvement in the third and fourth lanes which form preferred embodiments of the invention with respect to properties as described and of which are believed to be most responsible for the softness and wipeability of the sheet material of the invention are clear.

209853/0908

- 44 -

In view of the foregoing description of specific embodiments of the process and products of the present invention In accordance with the invention, it will be seen that the invention provides a new and improved form of sheet material which is a combination has properties that were previously not achievable in paper webs. This is how the sheet materials are of the present invention quite strongly as a result of the elastomeric binding material incorporated therein, however also extremely soft and bulky, as it is due to the high TEA to stiffness ratio and shows the low density. Furthermore, the sheet material according to the invention has an essential Stretching in all directions in its own plane originating from the elastomeric joints in those cases where differential or patterned creping is used, from the structure so formed. One of the Surprising features of the method of the invention is the simplicity by which the products according to the invention are formed particularly with regard to some of the alternative methods used in the past, to achieve some of these characteristics individually.

From the foregoing it will be seen that various modifications in the process and products can be made within the scope of the invention. For example, the Vary the composition of the binding material quite widely, as well as the pattern in which the binding material is attached to the web. Furthermore, the special device that is used to Execution of the method according to the invention is used, not indicative. For example, a wide variety of various means for drying the web, creping the web and applying the binding material the train can be used. As a result, the invention is not limited to the specific details of the method described herein and the products are limited.

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- 45 -

Claims (24)

- 45 claims 1.) Process for the production of a soft, absorbent, creped fibrous sheet material with the steps of mixing a fiber input from lignocellulosic fibers and water, the formation of a web from the 3-fiber input by introducing this fiber input into a drainage zone in which it perforated at least one Touches the support surface, which allows the removal of water therefrom, the adherence of the web to a creping surface and the removal of the web from this surface by a creping blade, characterized by the admixture of an elastomeric binding material in the fiber insert and after formation of the web the removal of additional water from it without mechanical compression until it is at least $ 80> dry before sticking the web to the crepe surface. 2. The method according to claim 1, characterized in that the web is treated to remove additional water therefrom without mechanical compression until it is at least 95 Ί » dry before it is sent to the crepe. rungsoberflache is glued. 3. The method according to claim T or 2, characterized in that that the web is adhered to the creping surface with an adhesive. 4. The method according to claim 3 »characterized by the application of the adhesive to a surface of the web and bringing that one surface into engagement with the creping surface. - 46 209853/0908 5. The method according to claim 3 »characterized by the application of the adhesive to the creping surface and bringing the web into engagement with that creping surface. 6. The method according to any one of the preceding claims, characterized in that it includes pressing the web into engagement with the creping surface. 7. The method according to any one of the preceding claims, characterized in that the creping surface is heated and that the step of adding moisture to the web immediately prior to adhering it to the Creping surface is contained therein, as well as the evaporation of said moisture by heat from the Crepe surface. 8. The method according to claim 7, characterized in that the additional moisture makes the web less than 90 % dry. 9. The method according to any one of the preceding claims, characterized by promoting the formation of the web and the removal of water from it by applying a partial Vacuum to a surface of the web prior to adhering the web to a creping surface. 10. The method according to claim 9, characterized in that it involves the application of a partial vacuum to a surface of the web while in the drainage zone for removal of water therefrom, as well as the Applying a partial vacuum to the opposite surface of the web to keep it out of contact with the remove perforated support surface. 209853/0908 ~ ⁴⁷ ~ 11. The method according to claim 10, characterized in that it involves the application of a partial vacuum to a surface of the web after it is out of contact with the perforated support surface has been removed. 12. The method according to any one of the preceding claims, characterized by the passage of air through the web until it üb water prior to the attachment thereof to the dry Kreppierungsoberfläche least 80 i »to remove therefrom. 13. The method according to any one of the preceding claims, characterized in that only selected areas or areas of the web to be glued or tacked to the crepe surface. 14. The method according to claim 13, characterized by the attachment the adhesive on selected areas of the web and pressing the web into engagement with the creping surface, whereby only the selected areas of the web are adhered to the crepe surface. 15. The method of claim _13f characterized by applying the adhesive to selected areas of the creping surface and pressing the web into engagement with the creping surface, whereby only areas of the web contacting the selected areas are adhered to the creping surface. 16. The method according to claim 14 or 15 »characterized in that that the adhesive includes an elastomeric binder, which fibers in the selected Areas of the web or in areas of the web which binds together the selected areas of the creping surface touch to a greater extent than in other areas of the track gQ9853 / 0908 - 48 - 17. Method according to one of the preceding claims, characterized in that the web is initially under conditions is formed resulting from very low interfiber bond strength result from natural bonds. 18. The method according to any one of the preceding claims, characterized in that the fibers prior to the formation of the web treated with a delivery agent to their Reduce inter-fiber link capacity. 19. The method according to claim 18, characterized by the addition a quantity of debinding agent to the fiber entry, which is sufficient to reduce the breaking length of a flat sheet to less than 800 meters, which consists essentially of such fibers. 20. Soft, absorbent, creped, fibrous web formed by deposition from an aqueous slurry after the process is formed according to claim 1, characterized in that the web is randomly arranged touching lignocellulosic Fibers and an elastomeric binding material at substantially uniformly distributed points of contact contains between said fibers generally throughout the web in order to provide structural integrity to the web to grant, with the web having a basis weight of about 4.54 kg to about 13.6 kg per 2675520 cm ² (10-30 lbs / 2880ft ² ) has a tensil energy absorption to stiffness ratio greater than 1.50 χ 10 and a mean calculated density by their thickness under no load of less than 0.300 grams per cubic centimeter. - 49 - 209853/0908 21. Soft, absorbent, creped, fibrous web after Claim 20, characterized in that the fibers have a natural inter-fiber binding capacity, the results from treatment with a debinding agent, such that a flat sheet consisting essentially of such fibers has a breaking length of less than 800 meters. 22. Soft, absorbent, creped, fibrous web according to claim 20 or 21, characterized in that additional Amounts of said elastomeric binding material in of the web are present in a predetermined pattern of higher strength web segments, which are divided by lower strength Track segments are at a distance. 23. A soft, absorbent, creped, fibrous web according to claim 22, characterized in that the predetermined Sample of said elastomeric binding material in the path is a continuous web-like pattern, which is a broken, predetermined, intermittent one Pattern of separate, less solid track segments certainly. 24. Soft, absorbent, creped, fibrous web according to any one of claims 20-23 »characterized in that the web train energy absorption-to-stiffness ratio (TEA-to-stiffness ratio), which is greater than 2.0 χ 10 " ⁴ is. 0 / G 209853/0908 . so. Blank page