MXPA00006169A - Paper products and methods for applying chemical additives to cellulosic fibers - Google Patents

Abstract

Chemical additives can be adsorbed on cellulosic papermaking fibers at high levels with a minimal amount of unadsorbed chemical additives present in the papermaking process water. A method includes treating a fiber slurry with an excess of the chemical additive, allowing sufficient residence time for adsorption to occur, filtering the slurry to remove unadsorbed chemical additives, and redispersing the filtered pulp with fresh water. Filtrate from the thickening process contains unadsorbed chemical additive and it is not sent forward in the process with the chemically treated fibers. The method can beemployed to make improved paper products.

Description

PAPER PRODUCTS AND METHODS FOR APPLYING CHEMICAL ADDITIVES TO CELLULOSE FIBERS Background of the Invention The present invention relates generally to paper products. More particularly, the invention relates to methods for applying chemical additives to cellulosic fibers to the paper products obtainable by the methods.

In the manufacture of paper products, it is often desirable to improve physical and / or optical properties by the addition of chemical additives. Examples of properties that are developed or improved through the addition of chemical additives include but are not limited to dry strength, wet strength, softness to absorbency, opacity, brilliance , and to color During the papermaking process, chemical additives are commonly added to the fiber solutions at the humid extremity, before the fibers are formed into a fabric, drains and dries. Traditionally, the extremite wet additives are added to a fiber solution that is between 0.5 and 5% consistency. The solution can then be further diluted in the papermaking process before a final dilution in the fan pump to the final formation consistency.

Chemical addition of wet end has several advantages over topical spraying, printing or chemical addition methods of sizing press. For example, the addition of wet end chemistry provides a uniform distribution of chemical additives over fiber surfaces. Additionally, the wet end chemical addition allows a selected fiber fraction to be treated with a specific chemical additive in order to improve the operation of the paper and / or the effectiveness of the chemical additive. In addition, the addition of wet end chemistry allows multiple chemicals to be added to the fiber solution, either simultaneously or sequentially, prior to paper tissue formation.

A difficulty associated with wet end chemical addition is that the water dispersible or water soluble chemical additives are suspended in the water and are not completely absorbed onto the cellulosic fibers. To improve the absorption of wet end additives, chemical additives are frequently modified with functional groups to impart an electrical charge when they are in water. The electrokinetic attraction between the charged additives and the anionically loaded fiber surfaces aids in the deposition and retention of chemical additives on the fibers. Notwithstanding this, the amount of chemical additive that can be retained at the wet end generally follows an adsorption curve that exhibits a diminishing effectiveness, similar to that described by Lagmuir. As a result of this, the adsorption of water-soluble water-dispersible chemical additives can be significantly less than 100 percent, particularly when trying to achieve high loading levels of chemical additives.

Consequently, at any level of chemical additive, and particularly at high addition levels, only a fraction of the chemical additive is retained on the surface of the fiber. The distant fraction of the chemical additive remained dissolved or dispersed in the suspension water phase. Non-adsorbed chemical additives can cause a number of problems in the papermaking process. The exact nature of the chemical additive will determine the specific problem that may arise, but a partial list of the problems that can result from non-adsorbed chemical additives include: foam, deposits, contamination of other fiber streams, poor fiber retention on the machine , a chemical layer purity compromised in multi-layer products, accumulation of dissolved solids in the water system, interactions with other process chemicals, clogging of felt or fabric, adhesion or excessive release on the dryer surfaces, a variability of physical properties in the finished product, similar.

Therefore, what is required and lacking in the art is a method to apply adsorbable chemical additives on the surfaces of cellulosic fibers at the wet end of the papermaking process so that the amount of non-adsorbed chemical additives in the water of process is reduced or eliminated. The method minimizes manufacturing problems of associated finished product quality that could otherwise occur.

Synthesis of the Invention It has now been discovered that chemical additives can be adsorbed onto the fibers to make cellulosic paper at higher levels with a minimum amount of non-adsorbed chemical additives present in the process water to paper. This is achieved by treating a fiber solution with an excess of the chemical additive, allowing a sufficient residence time for the adsorption to occur, filtering the solution to remove the adsorbed chemical additives, and redisperse the filtered pulp with fresh water. the filtering of the thickening process contains non-adsorbed chemical additives, this is not sent forward in the process with the chemically treated fibers. Rather, filtering can be sent to the sink or reused in the processing area before the filtration step.

Therefore, in one aspect the invention resides in a method for applying chemical additives to cellulosic fibers. The method comprises the steps of: creating a fiber solution comprising water, cellulosic fibers, and an adsorbable chemical additive, draining the fiber solution to remove the non-adsorbed chemical additive; and redispersing the fibers with fresh water This method for processing the fibers to make cellulosic paper allows the chemical additives to be adsorbed by the fibers while at the same time maintaining significantly lower levels of non-adsorbed chemical additives in the water phase compared to the chemical addition of traditional wet end. Therefore, the higher concentrations of the chemical additive on the fiber in relation to the process water can be achieved compared to what has been possible with the previous methods.

For the purposes of the present invention the term "cellulosic" refers to papermaking fibers comprising an amorphous carbohydrate polymer, in contrast to cellulosic fibers. The term "adsorbable" is used herein to refer to a chemical additive that can be assimilated by the surface of a cellulosic fiber in the absence of any chemical reaction involving the chemical additive and the cellulosic fibr. The term "non-adsorbed" refers to any part of the chemical additive that is not adsorbed by the fiber and therefore remains suspended in the process water. The term "fresh water" is used herein to refer to water that is essentially free of the non-adsorbed chemical additive. More desirably, fresh water is completely free of chemical additive.

The fiber solution is desirably drained to increase the consistency of the fiber solution to about 20 percent or more, and particularly about 30 percent or more, in order to remove most of the water containing the non-adsorbed chemical additive. . The fibers are then redispersed, desirably to decrease the consistency of the fiber solution to a suitable level for making paper, about 20 percent or less, and more particularly to about percent or less, such as about 3 to about of 5 percent.

The present method allows the production of fiber supplies that are useful for making paper products and particularly layered paper products. Therefore, another aspect of the invention resides in a fiber supply having a chemical additive charge higher than that which could otherwise be achieved in combination with a relatively low level of chemical additive not adsorbed in the water. This is because the loading of chemical additive through the addition of traditional wet end is often limited by the non-adsorbed chemical level d and its associated processing difficulties such as foam, deposits, chemical interactions, felt clogging , the adhesion or release of excessive drier or a variety of control issues d physical property of paper caused by the presence of chemically not adsorbed in water. ~~ In one embodiment, a fiber supply of the present invention comprises water, cellulosic fibers, and an adsorbable chemical additive. The amount of the chemical additive adsorbable on the fibers is about 2 kilograms per metric ton or greater, and the amount of chemical additive n adsorbed in the water is between 0 and about 20 percent of the amount of the chemical additive adsorbed on the fibers. In particularly desirable embodiments, the amount of adsorbed chemical additive is about kilograms / metric ton or greater, particularly about 4 kilograms / metric ton or greater, and more particularly about about 5 kilograms / metric ton higher. In addition, the amount of non-adsorbed chemical additive in the water is between 0 and about 15 percent, particularly between 0 and about 10 percent and more particularly between 0 and about 7 percent of the amount of the additive. chemical adsorbed.

Another aspect of the invention resides in a method for making chemically treated paper products. The method comprises the steps of: creating a first fiber solution comprising water, cellulosic fibers, and an adsorbable chemical additive; create a second fiber solution that is essentially free of an adsorbable chemical additive; draining the first fiber solution to remove the chemical additive n adsorbable; redispersing the fibers in the first fiber solution with fresh water; and forming a paper product using a layered head box, the first fibr solution supplied to a first head box layer and the second fiber solution supplied to a second head box layer.

In another embodiment, a method for making a paper product comprises the steps of: creating a fiber solution comprising water, cellulosic fibers and a first adsorbable chemical additive; drain the fiber solution to a consistency of about 20 percent or more; pass the drained fiber solution through a couple disperser to mechanically work the fibers; diluting the fibr solution with fresh water that is essentially free of the first chemical additive at a consistency of about 5 percent or less, adding a second adsorbable chemical additive comprising either a debinding agent or a softening agent for the fiber solution; dewatering the fiber solution to a consistency of about 20 percent or more, diluting the fiber solution with fresh water that is essentially free of the second chemical additive at a consistency of about 5 percent or less; and form a paper product of the fiber solution. The first chemical additive may comprise, for example, a binder agent to decrease the amount of lint of the product.

The present invention is particularly useful for adding chemical additives such as softening agents and debonding agents to the outer layer supplies in a three-ply paper product. In particular tis products, for example, the core layer is adapted to provide a development of strength and control. The present invention allows the softening agents and the binder agents to be applied to the outer layers while minimizing the contamination of the central strength layer.

Therefore, another aspect of the present invention resides in paper products formed from fibers that have been chemically treated to minimize the amount of residual non-adsorbed chemical additives in the process water. These paper products exhibit a high chemical "purity" on the fiber fraction that has been treated using the present method offer the ability to achieve a surplus chemical layer purity when using a stratified headbox and / or ability to achieve a specific chemical treatment of fiber in papers made of mixtures of two or more types of fibers. The term "paper" is used here to broadly include writing paper, printing, wrapping, industrial toipaper and paper, newsprint, liner board, tissue, napkins, cleansers, towels or the like.

Chemical additives that can be used in conjunction with the present invention include: dry strength auxiliaries, wet strength auxiliaries, softening agents, binder agents, absorbency aids, sizing agents, dyes, the optical brighteners, the chemical indicators, the opacifiers, the chemical adhesives of dryer, similar. Additional forms of chemical additives may include: pigments, emollients, humectants, viricides, bactericides, buffers, waxes, fluoropolymers, odor control and deodorant material, zeolites, perfumes, debanders, vegetable and mineral oils, humectants, sizing agents , superabsorbents, surfactants, humidifiers, ultraviolet blockers, antibiotic agents, lotions, fungicides, preservatives, aloe-vera extract, vitamin E, or the like. Suitable chemical additives are adsorbable by fibers to make cellulosic paper and are either water dispersible or water soluble.

The term "softening agent" refers to any chemical additive that can be incorporated into paper products such as a tissue to provide an improved feel. These chemicals may also act as dissociating agents or may act only to improve the surface characteristics of the tissue, such as by reducing the coefficient of friction between the tissue surface and the touch.

The term "debinding agent" refers to any chemicals that can be incorporated into paper products such as a tissue to prevent or interrupt the hydrogen bonding of the interfiber or intrafiber. Depending on the nature of the chemical, the binder agents can also act as softening agents. In contrast, the term "binding agent" refers to any chemical that can be incorporated into a tissue to increase or improve the level of interfiber or intrafiber binding in the sheet. The increased binding can be either ionic, hydrogen or covalent and nature.

The term "water soluble" refers to solid or liquids that will form a solution in water, and the term "water dispersible" refers to solids or liquids of colloidal size or larger that can be dispersed in an aqueous medium.

The method for applying chemical additives to papermaking fibers can be used in a wide variety of papermaking operations, including wet pressing, creped or non-creped continuous drying operations. By way of illustration, several processes are described for doing 'tis in the patent of the United States of North America No. 5.667.63 granted on September 16, 1997 to S.A. Engel and others; and U.S. Patent No. 5,607.55 issued March 4, 1997 to T.E. Farrington, Jr. and others; all of which are incorporated here by reference.

The method can also be used in alternating processes, including: chemical pretreatment pulp in a pulp mill before a dry-working wheel machine a crumb baler; add chemical additives in sequence to reduce interactions, remove chemical additives from a fiber solution (neutralizing anionic components, sizing or softening formulas) after the chemical additive has been added to facilitate the removal process; or similar.

Many types of fibers can be used for the present invention including the fibers of hardwood or softwood, straw, flax, loose silk fibers of benzene seed, abaca, hemp, soft rush, bagasse, cotton, cane, and the like. . All known papermaking fibers can be used, including bleached and unbleached fibers, fibers of natural origin (including wood fibers other cellulosic fibers, cellulose derivatives, and crosslinked or clinically stiffened fibers), some of which are component parts of the fibers. Synthetic fibers (fibers for synthetic paper include certain forms of fibers made d polypropylene, acrylic, aramides, acetates and the like), virgin and reclaimed or recycled fiber, hardwood and softwood, and fibers that have been mechanically pulped (for example, ground wood), which have been chemically reduced to pulp, including but not not limited to the reduction processes of sulfite and kraft pulp, reduction to pulp thermomechanically reduction to quimotermomecánicamente pulp, and the like. Mixtures of any sub-set of the aforementioned or related fiber classes can be used. The fibers can be prepared in a multiplicity of ways known to be advantageous in the art. Useful methods for making fiber include the dispersion for imparting curl and improved drying properties, such as described in US Pat. No. 5,348,620 issued September 20, 1994 and 5,501,768 granted March 26, 1996, both to MA Hermans et al. And U.S. Patent No. 5,656,132 issued August 12, 1997 Farrington, Jr. et al.

A single head box or a plurality of headbox can be used. The headbox or headboxes may be laminated to allow the production of a multi-layer structure of a headbox jet in the formation of a fabric. In particular embodiments, the fabric is produced with a stratified or layered headbox to preferably deposit shorter fiber on one side of the fabric for improved softness with relatively longer fibers on the other side of the fabric or in an inner layer of fabric. a fabric having three or more layers The fabric is desirably formed on an endless loop d a perforated forming fabric which allows draining of liquid and partial drainage of the fabric. The multiple embryonic tissues of the multiple head boxes can be chemically or mechanically joined in the wet state to create a single tissue having multiple layers.

Numerous features and advantages of the present invention will appear from the following description. In the description reference is made to the accompanying drawings which illustrate the preferred embodiments of the invention. Such incorporations do not represent the full scope of the invention. Reference should therefore be made to the claims given herein to interpret the full scope of the invention.

Brief Description of the Drawings Figure 1 shows a schematic process flow chart of a method according to the present invention for treating fibers for making paper with chemical additives.

Figure 2 shows a schematic process flow diagram of a method according to the present invention for both treating the fibers for making paper with chemical additives and for mechanically treating the fibers using a disperser.

Figure 3 shows a schematic process flow diagram for a method for making a creped n paper sheet.

Detailed Description of the Drawings The invention will now be described in more detail with reference to the figures. For simplicity, the various tensioning rollers used schematically to define the various fabric runs are shown but not numbered to the similar elements in the different figures have been given the same reference numbers. A variety of conventional papermaking apparatus and operations can be used co with respect to the supply preparation, the headbox, the forming fabrics, the fabric transferors, the creping on drying. However, the particular conventional components are illustrated for purposes of providing the context in which the various embodiments of the invention can be used.

Figure 1 shows a preparation preparation equipment used to apply chemical additives to the papermaking fibers according to an embodiment of the present invention. The supply preparation equipment comprises a first cassette 10, a second supply cassette 12 and a dewatering device 14 operably placed between the supply cassettes. The fibers for making paper and water are added to the first supply box 10 to form a fiber solution 20. The fiber solution in the first box of supply desirably has a consistency of about 20 percent lower, and particularly of about 5 percent lower, such as from around 3 to about 5 percent. The fiber solution in the first supply box is desirably under agitation using a mixed blade, rotor, recirculation pump, or other suitable device 18 for mixing the fiber solution.

One or more chemical additives 24 are administered from a tank 26 and added to the fiber solution 20 in the first supply box 10. The amount of chemical additive 2 is suitably from about 5 to about 2 kilograms / metric ton. In particular embodiments, the chemical additive comprises an imidazoline-based binder agent and is added in a quantity of from about 7.5 to about 15 kilograms / metric ton. The fiber solution and the chemical additive are desirably left standing together in the first supply box under agitation for a sufficient residence time to allow the paper fibers to adsorb a substantial part of the chemical additive 24. A residence time d around from 15 to around 30 minutesFor example, it may be enough.

The fiber solution 20 is then transferred through the appropriate conduits 27 and from a pump 28 to the drain device 14. In the illustrated embodiment, the drain device comprises a band press 14, even when alternate drainage devices such as a Centrifugal, a pressure point thickener or the like can be used. The fiber solution is injected between a pair of perforated fabric 30 so that the press filtrate 32 is removed from the solution. The press filtrate 32 comprises a part of process water together with the non-adsorbed chemical additives 2 in the water. The band press 14 or other suitably dewatered device increases the fiber consistency of the solution to about 20 percent or more, and particularly to about 30 percent or more. The non-adsorbed chemical additive can be removed from the process or used as dilution water in the previous preparation steps, but in an important way it is not sent forward with the chemically treated supply.

The thickened fiber solution 20 is then transported through the conduits 34 to the second cassette d. supply 12. The fiber solution is then rediluted with fresh water 35 from a suitable reservoir 36 and optionally stirred using a mixing device 18. The fiber consistency of the solution is suitably decreased to about 20 percent or less and particularly about 5 percent or less, such as around 3 about 5 percent. The fiber solution can then be removed from the second supply box through suitable conduits 37 and from a pump 38 for subsequent processing 39. Alternatively, the fibr solution can be processed through the above procedure again in an effort to further increase the level of retention of chemical additive.

Figure 2 shows an alternate embodiment of the present invention in which the supply preparation equipment was used to apply chemical additives to make fibers to make paper and to mechanically treat the fibers. In general, the equipment comprises three supply chests 10, 1 and 40, two dewatering devices 14 and 42, two dilution buffers 44 and 46, and a disperser 48 for mechanically treating the fibers for making paper.

The fibers for making paper and water are added to the first supply box 10 to form a fiber solution 20. The first solution in the first supply box desirably has a consistency of about 20 percent or less, and more particularly around 5 percent or lower. One or more chemical additives 24 are supplied from a tank 26 and fiber 20 is added to the solution 20 in the first supply box 10 while under agitation 18. The first chemical additive added to the fiber solution is desirably a cationic agglutinating agent. which is used to control the lint in the finished product. The first chemical additive is not desirably a softening agent or an anti-caking agent which could reduce the efficiency of the disperser.

After a sufficient residence time, the fiber solution is transferred through suitable conduits 27 and from a pump 28 to a band press 14 other suitable dewatering device. The chemical additives n adsorbed in the water are removed from the press filtrate 32 during the pressing operation and are stored in the first dilution water cask 44. The contents of the first cask of dilution water can be used as either water of manufacture. of the reducer to pulp or dilution water or can be discarded The drain device 14 suitably increases the consistency of the fiber of the solution to about 20 percent or more, and particularly to about 30 percent more.

The thickened fiber solution 20 is then transported through the suitable conduits 34 to the disperser 48 for the mechanical treatment of the fibers. Suitable dispersants for use in the present method are described in U.S. Patents of North America No. 5,348,620 issued September 20, 1994 and 5,501,776 issued March 26, 1996, both to M.A. Hermans and others, which are incorporated here by reference.

After dispersion, the fiber solution is transported through the conduits 50 to the second supply coffer 12. A second chemical additive or a second group of chemical additives 52 are supplied from a reservoir 53 are added to the fiber solution 20 in the second supply box 12 while under agitation 18. Additionally, the fiber solution can optionally be diluted with the filtrate 56 from a source described hereinafter, the fiber consistency of the solutions being adequately decreased around 20 percent or lower, particularly around 5 percent lower, such as d around 3 to about 5 percent. In the particular embodiments, the second chemical additive 5 comprises a softening agent and / or a binder agent, and the fiber solution is not subjected to high cut refining forces such as those generated in a disperser once the softening agent and / or binder is added to the fiber solution. - After a sufficient residence time to allow the adsorption of the second chemical additive, the fiber solution 20 is transferred from the second supply box 12 through suitable conduits 58 and from a pump 59 to the second drain device 42. non-adsorbed portions of the second chemical additive 52 in the water are removed with the press filtrate 56 during the pressing operation and stored in the second dilution water box 46. The contents of the second water dilution box can be added to the second Supply chest 12 as described above or can be discarded. The second drainage device 42 suitably increases the fiber consistency of the solution to about 20 percent or more, and particularly to about 30 percent or more.

The thickened fiber solution 20 is then transported through the conduits 58 to the third supply cup 40. The fiber solution is then rediluted with fresh water from a suitable reservoir 36 and optionally stirred using a mixing device 18. L The fiber consistency of the solution is suitably lowered to about 20 percent or lower, and particularly about 5 percent lower, such as about 3 about 5 percent. The fiber solution can then be removed from the third supply box through suitable conduits 37 and a pump 38 for subsequent processing 39. Alternatively, the fiber solution can be returned to the second supply box 12 for repeated application of the fiber. second chemical additive 52.

A suitable process 39 for making the paper products of the fiber solutions 20 of FIGS. 1 or 2 is the non-creped continuous drying method shown in FIG. 3. The non-creped continuous drying method is also described in the United States of America No. 5,656.13 issued August 12, 1997 to Farrington, Jr. and others which is incorporated herein by reference. A twin wire former having a head box for making paper in layer 60 injects or deposits a stream of fiber solution 2 on the forming fabric 62 to form a cellulosic fabric 64. The fabric is then transferred to the fabric 66, the which serves to support and carry the newly formed moist tissue in the process as the fabric is partially dewatered to a consistency of about 10 percent by dry weight. Further dewatering of the wet fabric can be carried out, such as by vacuum suction, while the wet fabric is held by the forming fabric.

The wet fabric is then transferred from the forming fabric 66 to a transfer fabric 70 which travels at a slower speed than the forming fabric in order to impart a stretch in the direction of the machine to the fabric. A kiss transfer is carried out to prevent compression of the wet tissue, preferably with the aid of a vacuum shoe 72. The transfer fabric can be a fabric having print knuckles or it can be a softer fabric such as Asten 934, 937, 939, 959 or Albany 94M. If the transfer cord is of the print knuckle type described here, it can be used to impart some of the properties as the continuous drying cloth and can improve the effect when coupled with a continuous drying cloth also having the knuckles of printing . When a transfer fabric having the print knuckles is used to achieve the desired cross directional stretching properties, this provides the flexibility to optionally use a continuous or different drying fabric, such as one having a pattern or wave pattern. Decorative pair provide additional desirable properties that could not be achieved otherwise.

The fabric is then transferred from the transfer fabric to a continuous drying fabric 74 with the aid of either a transfer roller with vacuum 76 or a transfer shoe with vacuum. The continuous drying fabric may be displaced at about the same speed or at a different speed relative to the transfer fabric. If desired, the continuous drying fabric can be run at a slower speed to further improve the stretch in the machine direction. The transfer is then carried out with the help of the vacuum to ensure a deformation of the sheet to conform to the continuous drying fabric, thereby giving a desired flexibility, volume, stretch in the transverse direction and appearance. The continuous drying fabric and preferably of the print knuckle type.

The level of vacuum used for tissue transfers can be from about 3 to about 1 inch (about 75 to about 380 millimeters) d mercury, preferably about 10 to about 1 inch (about 254). to around 380 millimeters) d mercury. The vacuum shoe (negative pressure) can be complemented or replaced by the use of positive pressure from the opposite side of the fabric to blow the fabric over the next fabric in addition to or as a replacement to suck on the next fabric with vacuum. Also, a roller with vacuum rollers can be used to replace the shoe with vacuum shoes.

The specific incorporations and modes of operation that refer to the forming fabric, to the transfer cloth, to the rapid transfer, to the transfer shoes, to the placement of fabric, and to the vacuum levels are discussed in the patent of United States of America No. 5,667,636 granted on September 16, 199 to SA Engel et al. And US Pat. No. 5,607,551 issued March 4, 1997 to T.E. Farrington, Jr. and others which are incorporated herein by reference.

While held by the continuous dry cloth, the fabric is finally dried to a consistency of about 94 percent or more of the continuous dryer 80 then transferred to a carrier fabric 82. The dried bas leaf is transported to the carrier fabric. spool 84 using the carrier fabric 8 and an optional carrier fabric 86. An optional pressurized flip roller 88 can be used to facilitate the transfer of the fabric from the carrier fabric 82 to the fabric 86. The carrier fabrics suitable for this purpose are Alban International 84M or 94M and Asten 959 or 937, all of which are relatively smooth fabrics having a fine pattern. The tissue roll can then be calendered, cut, treated on the surface with emollient or softening agents, etched similarly in subsequent operations to produce the final product form.

EXAMPLES The following examples serve to illustrate the possible approaches pertaining to the present invention. The particular amounts, proportions, parameter compositions are intended to be exemplary, and are not intended to specifically limit the scope of the invention.

Example 1 (Comparative) For this example, a softening / debonding agent was added during the production of a multi-fiber three-layer tissue using a conventional packing box chemical addition method. The supply used for the two outer layers comprised 70% eucalyptus fibers, 29% broken tissue and 1% recycled fiber core supply. The outer layer supply components were mixed in the pulp reducer. After reducing them to pulp, the supply was transferred to a hood and treated with a binder agent, Parez 63INC which is commercially available from Cytec Industries, Inc., at a dose of 1 kilogram / metric ton. After allowing the solution to mix for 2 minutes, the supply was thickened to more than a consistency of 30 using a drain press and treated in a disperser to impart curl to the fibers. The disperser was operated with a force input of 80 kilowatts and an output supply temperature of around 180oF. After dispersing, the fibers were stored in a high density chest until required during the manufacture of the tissue.

At the time of manufacture, the outer cap supply, consisting of the eucalyptus / broken / supplied dispersed core mixture, was diluted to a 3.5% consistency in a box using the filtering from the previous thickening process. A softening / debonding agent, C-6092 which is commercially available from Witco Corporation, was added to this supply at a rate of 6.5 kilograms / metric ton in the cassette packing box recirculation circuit. This packing box supplies the fan pumps for both outer layers of a three-layer tissue sheet.

The central layer supply comprises 100% d kraft fibers from bleached soft wood from the north. This supply was refined to a power input of 2 days horsepower / metric ton for a dry strength development. The Parez 631NC was also added to this supply at a dose of 5.8 kilograms / metric ton to achieve control of wet tensile strength. E dry strength control was achieved by varying the ratio of the core layer to the outer layer supply.

A tissue dried through dried air from a cap was produced using a pilot tissue machine. This same tissue machine was used for Examples 1-4. The machine contains a three-layer head box of which the outer layer containing the same supply (70% eucalyptus, 29 broken, 1% core supply) and the core layer was 100% softwood fiber . The resulting trellis sheet structure was formed on a twin-wire former, d-shaped roll. The speed of the forming cloths was 2250 feet per minute (fpm). The newly formed fabric was then drained at a consistency of about 20-27% using a vacuum suction from below the forming fabric before transferring to the transfer cloth, which has been displaced at 1800 feet per minute (25 % fast transfer). A vacuum shoe pulling about 10 inches of mercury vacuum was used to transfer the fabric to the transfer cloth. The fabric was then transferred to a continuous drying fabric by moving at a rate of about 1800 feet per minute. The fabric was carried over a pair of Honeycom continuous dryers operating at temperatures around 325 ° F and dried to a final dryness of about 94-98 percent consistency.

The air-dried base weight of the sheet was 27. grams per square meter. The proportion of final fiber in the sheet was 32% of soft wood fiber (in the middle layer) of 68% of a mixture of eucalyptus / broken / core supply (outer layers). The final resistance of the tissue was 80 grams by 3 inches in width (resistance to the geometric head tension).

Example 2 For this example, the improved chemical addition method shown in Figure 1 was used to treat or supply with a softening / debonding agent. The treated supply was then used as the outer cap supply in a multi-layer three-layer tissue structure. Because the improved chemical addition method removes most of the softening / debonding agent n retained from the water phase during tissue formation, the resulting product can be produced at an equivalent tensile strength, at a softener / deagglutinant content. and a lower softwood fiber content than a tissue made with the identical softening agent using the conventional chemical addition method described in Example 1.

In Example 2, the supply used for the outer layers comprised 70% eucalyptus fibers, 29% broken tissue and 1% recycled fiber core supply During the supply preparation phase, the supply of outer layer was mixed during pulping and s placed in a storage box at a consistency of 3.5 The supply was then treated as a binding agent, Parez 63 INC of Cytec Industries, Inc., at a dose of kilogram / metric ton. After leaving the solution and mixing for 20 minutes, a softening / debonding agent, C-6092 from Witco Corporation, was added at a dose of 7.5 kilograms of chemical additive / metric tonne d fiber. After an additional 20 minutes of mixing time, the solution was drained using a band press approximately a 32 percent consistency. The filtering of the drainage process was used as water from the pulp reducer for subsequent loads but was not sent forward in the preparation of the supply or the tissue manufacturing process. The thickened pulp was then passed through a dispersion with a force input of 80 kilowatts and a supply temperature of about 180oF to impart the curl to the fibers. After the dispersion operation, the supply was placed in a high density storage chest as needed during the manufacturing of the tissue.

A tissue dried through air, not creped, and a layer was made using a three layer head layer, as described in Example 1. The supply for the two outer layers comprised the 32% supply mix d chemically treated eucalyptus / broken / core d supply, which had been rediluted to 3% consistency with fresh agu in a shallow flask. The core layer consisted of 100% softwood fibers refined to a power input of 2 horsepower / metric ton, to which 5.8 kilograms / one metric of Parez 631NC was added for wet strength control. The dry strength control of the finished product was achieved by adjusting the ratio of the core layer and the supply of the outer layer to the sheet.

The air-dried base weight of the sheet was 27. grams per square meter. The proportion of final fiber in the sheet was 17% of soft wood fiber (in the center layer) and 83% of the eucalyptus / broken / core supply mix (outer layers). The final resistance of the tissue was 80 grams by 3 inches in width (resistance to the geometric head tension).

Example 3 For this example, the improved chemical addition method shown in Figure 2 was used to first treat or supply with a binding people, mechanically modify the fibers using a disperser, and then treat the delivery with a softening / debonding agent. The chemically treated feed was used as a supply in a multi-fiber three-ply tissue structure. Because the improved chemical addition method removes the majority of non-retained softening / debonding agent from the water phase during tissue formation, the resulting product was much stronger (in an equal fiber composition) than a tissue made with a tissue. similar softening agent using the conventional chemical addition method described in Example 1. In addition, because the softener / binder is not present in the supply during the dispersing operation, there is more efficient transfer of energy to the fibers. This results in a higher level of binder than that demonstrated in Example 2 due to the fiber curling properties imparted during dispersion.

In Example 3, the supply used for the outer layers comprised 70% eucalyptus fibers, 29% broken tissue and 1% recycled fiber core supply. During the supply preparation phase, the supply of the outer layer was mixed during pulping and placed in a supply box at a consistency of 3.5%. The supply was then treated with a binding agent, Parez 63 IN from Cytec Industries, Inc., at a dose of 1 kilogram / metric ton. After allowing the solution to mix for 2 minutes, the supply was drained using a d band thickener at a consistency greater than 30%. The thickened pulp was then passed through a disperser with a force input of 80 kilowatts and a delivery temperature of about 180 ° F to impart the curl to the fibers. The dispersed pulp of superior consistency was then stored in a chest until sufficient quantities could be produced.

In order to treat the supply with a second chemical additive, the high consistency pulp was then diluted to a 3.5% consistency with a combination of fresh water and a thickener filtrate (containing the non-adsorbed softening / debonding agent) as shown in Figure 2. The supply was then treated with 7. ki 1 ogram or 1 metric meter of a softening / debonding agent C-6092 from Witco Corporation, and allowed to mix for 20 minutes. The supply was then drained using a band press of approximately 32% d consistency. The filtering of the drainage process was used with partial dilution water for the dilution step of high consistency supply, as previously mentioned. After the second thickening operation, the supply was placed in a high density storage chest until required during the manufacturing of the tissue.

A tissue dried through non-creped air and a layer was made using a three-layer headbox, as described in Example 1. The supply for the two outer layers comprised 32% consistency of a eucalyptus / broken mixture. / supply of chemically treated core which had been rediluted to a consistency of 3% with fresh water in a box under agitation. The core layer comprised 100% softwood fiber refined to an energy input of 2 days horsepower / metric ton to which 5.8 kilograms / metric ton of Parez 631NC had been added for wet strength control. The dry strength control of the finished product was achieved by adjusting the proportion of the central layer and the supply of outer layer in the sheet.

The dry basis weight in air of the leaf was 27. grams per square meter. The proportion of final fiber in the sheet was 24% of soft wood fiber (in the center layer) and 76% of the eucalyptus / broken / core supply (outer layers). The final resistance of the tissue was 80 grams by 3 inches in width (resistance to the geometric head tension).

Example 4 = This example is similar to Example 3 except that 15 kilograms / metric ton d softener / debitter C-6092 was added to the outer layer supply (instead of 7.5 kilograms / metric ton of Example 3).

Because the improved chemical addition method has removed the majority of the non-retained softening / debonding agent from the water phase during tissue formation, the resultant product contains 55% or more softening / debonding agent than the product described in Example 1, at an equivalent tensile strength and fiber composition.

The delivery preparation and the tissue manufacturing processes were identical to those of Example 3. The base weight of dry air of the sheet was 27.5 grams per square meter. The proportion of final fiber in the sheet was 31% d softwood fiber (in the center layer) and 69% of the eucalyptus / broken / core supply (in the outer layer) mix. The final resistance of the tissue was 795 grams po 3 inches wide (resistance to geometric head tension).

The results shown in Table 1 given below indicate that a layered tissue sheet can be made with a geometric head tension strength of about 800 grams by 3 inches wide (795 grams by 3 inches wide) under the conditions of processing described in Example 4, containing 31% softwood fiber and 5.9 kilograms / metric tonne of binder / softener C-6092 retained by using the improved chemical addition method. When using the conventional chemical addition method described in Example 1, and the otherwise identical manufacturing conditions, a layered tissue sheet with a main geometric stress strength of 800 g / 3 inches of width contains 32% of soft wood fiber but only 3. kilograms / metric ton softener / binder C-609 retained. The reason for this difference in the C-6092 retained tissue equivalent resistance, is concluded by hypothesis, which is because the deagglutinating characteristic of C-6092 n adsorbed in the conventional chemical addition method comprises the development of resistance of the soft wood fibers in the central layer. As a result of this, more soft wood fibr is required to achieve the same tensile strength of the finished product.

By using the improved chemical addition method, the tissue / chemical fiber combinations can be produced at target strength levels that can not otherwise be made using conventional chemical addition methods. In Examples 2-4, the tissues were manufactured with the basis weight and generally constant strength by adjusting the relative amounts of softwood and hardwood. Of course, various alternatives are possible such as maintaining the resistance generally constant and a proportion of softwood / hardwood and adjusting the basis weight.

TABLE 1 E plos 1-4 Resistance% Layer% Binder Layer Binder The operation (cr /: 3 DUlcf.) External Central Acrecuted Retained 1 800 32 68 4.4 3.8 2 802 17 83 6.2 4.6 3 806 24 76 5.7 3.8 4 795 31 69 10.4 5.9 In Table 1, "Resistance" refers to the resistance to the geometric head tension which is calculated for the purposes of the present invention according to the formula: / V [[((tensionMD) (tensidnCD.) Resistance to stress MD "of a tissue sample is the conventional measure, known to those skilled in the art, of the load of width per sample at the point of failure where a tissue of tissue is stressed in the direction of the machine. , the resistance to the "DC tension" is the analogous measure taken in the direction transverse to the machine.The tensile strength MD and C are measured using an Instron tension tester using a 3-inch jaw width, a jaw spacing of inches, and a crosshead speed of 10 inches per minute Before the test, the sample is maintained under TAPP conditions (73oF, 50% relative humidity) for 4 hours before the test.

Tension resistance was reported in units of grams po 3 inches wide (to the point of failure).

The% Central Layer and% Outer Layer refers to the percent by weight of the fibers in the appropriate layers.

The Aggregate Binder reflects the chemical additive that is added to the supply in kilogram / metric tonne of the complete sheet. This was calculated based on the aggregate level of the outer layer supply and the amount of outer layer supply in the final sheet.

The retained binder reflects the amount of chemical additive adsorbed on the tissue. The Desaglutinant Retained can be determined using the following procedure suitable for imidazoline-based chemical additives such as Witco C-6092 that are added to the tissue. The procedure refers to the aggregate percent, which has been converted to kilograms / metric ton (multiplied by 10) in Table 1.

In general, a sample of the tissue is weighed and extracted in a sealed container for a given amount of time on a flat bed shaker at ambient conditions. After the extraction, the tissue is removed and the extract is allowed to settle. The extract is then analyzed by ultraviolet spectrometer. After the percent extracted and calculated, the aggregate percent can be determined with reference to an aggregate correlation curve that is generated as described below.

The following equipment and chemicals are used: pipettes 1, 3, 5, 10 and 100 mL; volumetric bottles, 100 and d 1000 mL; sealed containers, eg, specimen cups; a flat bed agitator, such as an orbital bed shaker (Orbital Shaker Model for Laboratory Line No. 3590, from Lab Line Instruments, Inc.); an ultraviolet spectrometer (a Hewlett Packard Model 8451A Diode Array Spectrophotometer from Hewlett Packard); methanol, reagent class; imidazolino, standard such as Witco C-6092; beaker, 30 mL; and control tissues that differ from the tissue that is being tested only by the absence of the chemical additive that is being tested.

A standard imidazoline solution of supply (1000 ppm active) was prepared; weight 0.1250 grams of C-6092 (80% active) in a 30 mL weighted glass; transfer quantitatively to a 100 mL bottle with methanol; and dilute to mark methanol and invert several times.

The standard imidazoline solutions (10, 30, 50 and 100 ppm) were prepared: in four volumetric bottles of 100 mL, add 1, 3, 5 and 10 mL of the standard imidazolin solution of 1000 ppm; and dilute for co-methanol brands. The standards are 10, 30, 50 and 100 ppm, respectively.

Generate a Standard Solution Curve: With the UV spectrophotometer set at a wavelength of 238 nm, refer the instrument using a methanol sample. Read the absorbance of the standard solutions (10, 30, 50 and 100 ppm), then draw a concentration curve against the absorbance. Generate a suitable first-order equation for the data.

Nailing solutions (100 and 5000 ppm) are prepared in: Weight 1,250 and 6,250 grams of C-6092 in 50 mL beaker; transfer quantitatively to a 1000 ml bottle with distilled water; Shake well and let dissolve before diluting the brand. If excessive foam occurs, fill the stem with the bottle and add a small amount of methane to remove the foam and dilute to the mark and then invert several times. This makes nail solutions of 1000 ppm and 5000 ppm.

Generate an Aggregate Correlation Curve: A minimum of three duplicates must be carried out for each aggregate level and for the targets. It must be at least four levels of aggregate to generate a curve. The nailing solutions must be made with distilled water so that the nailing sample can be dried in an oven at 60 degrees Celsius.

Weigh 5.00 grams of the control tissue in a specimen container. For four levels, three duplicates, and blanks, prepare 15 samples. A typical curve should be d 0.1, 0.3, 0.8, and 1.0% of aggregate C-6092 based on the tissue weight.

The nailing samples with dipping solution and dried for 48 hours in an oven at 60 degrees Celsius. Use volumetric pipettes. Example: Nailing Solution Volume for a tissue of 5.00 grams Level Added 100 Oppm 00 Oppm White 0 mL 0 mL 0, .1% 5 mL 0. .3% 15 mL 0. .8% 8 mL 1. .0% 10 mL Add 100 mL of methanol using a pipette to seal the containers. Place on a flat bed shaker extract for% hour. Remove the tissue and leave the extract that is nods. With a transfer pipette, remove the supernatant and fill a glass receptacle with the spectrophotometer. Measure the absorbance at a wavelength of 238 nm using the UV spectrometer. A dilution of 1 to 10 may be required to stay within the standard curve. Whites should be read with and without this dilution. Subtract the absorbance readings from the targets. Use the 1/10 dilution white d readings for the 1/10 dilution samples and the undiluted blank readings for the undiluted samples The extracted percent is then calculated from the ppm reading of the standard curve (imidazoline) as follows: % Extracted (without dilution) = ppm read X 0.1 X 100/5000% Extracted (1/10 dilution) = ppm read X 0.1 X 10 X 100/5000 Construct an Aggregate Correlation curve with e percent of values extracted (y-axis) against the corresponding aggregate level (x-axis). Select the best adjustment curve (first or second order).

Sample Analysis: Weigh 5.00 grams of sample into a specimen container and add 100 mL of methanol Place on a flat bed shaker and extract for half an hour Remove the tissue and let it settle. Read the extracts at a wavelength of 238 nm and subtract the main white absorbency reading. Calculate the ppm of the standard curve then calculate the percent of value extracted. Use the aggregate correlation curve, calculate the aggregate percent with e percent of value extracted.

Imidazoline has a peak absorbance at a wavelength of 238 nm. While white tis extracts do not have this peak absorbance at 238 nm, it has some absorbance that interferes with quantification. Whites are very reproducible and can be subtracted for determination. It is important that the weight of the sample, the volume of methanol and the extraction time remain constant. An aggregate correlation curve should be generated for the different tissue samples because several chemicals used in the tissue process can affect the binding of imidazoline thus affecting recovery. The percentage added also affects the percent of recovery using several levels of aggregate to build the correlation curve helps determine the value added.

Example 5 _ To better illustrate the ability for the improved chemical addition method to remove non-adsorbed chemicals from the supply of a papermaking process, a laboratory-scale experiment was carried out. The objective of this experiment was to demonstrate how much non-adsorbed chemical is present in systems that do not use the improved addition method and compare this with systems in which the same amount of chemical is added using the improved method. The supply used in this experiment was 100% eucalyptus fibers. The chemical additive used was C-6092, a softener / debonder commercially available from Witc Corporation. Addition levels were 0.5% and 1.0% d active binder on dry fiber. 0.5% Addition Experiment: Step 1 During the experiment, 1800 grams of a fiber solution at a consistency of 2.5% (45 g dry fiber) was stirred using a mechanical mixer. To the stirred fibr solution, the appropriate amount of chemical C-609 was added in the form of an active 1% solution. The volume of C-609 1% active required for the 0.5% loading was 22.5 ml. After stirring at 15 minutes, 600 mL of the solution was removed and spread out on a plate to dry at room temperature under a cover. This sample will be mentioned as IA.

Step 2 The remaining 1200 grams of the solution was filtered using a Whatman 4 filter paper and a Buchner funnel apparatus. The filtration step simulates the drainage step of the improved chemical addition method shown in Figure 1. The filter pad (at a consistency of approximately 25%) was divided into two sections of an approximately equal mass. A section was placed on the cover to dry at room temperature. This sample will be mentioned as 2A.

Step 3 The other half of the filter pad (d approximately 600 g) was redispersed to a consistency of 2.5 using distilled water. The solution was stirred mechanically for 1 minute and then filtered using a Whatman filter paper and a Buchner funnel apparatus. This filtration step simulates the drainage that occurs in the drainage areas with vacuum and d formation of a tissue machine. The filter pad s placed on the cover to dry at room temperature. This sample will be mentioned as 3A. 1.0% Addition Experiment Steps 1-3 were repeated using a level of 1.0% addition of C-6092. The corresponding samples were coded IB, 2B and 3B.

All samples were analyzed for C-6092 content using methanol extraction followed by UV spectroscopic analysis at 238 nm compared to absorbance at acceptance to a known calibration curve. The results are shown in the table given below: Sample No.

Content of C-6092 (%) ÍA 2A 3A IB 2B 3B 0.51 0.30 0.28 1.05 0.73 0.68 The sample results of the impact of using the improved chemical addition method on the reduction of the amount of binder not adsorbed on the supply. Comparing the C-6092 content of samples IA and 2A showed that 41% of the chemistry is not sufficiently retained on the fibers and that it is removed during the drainage. If the method of chemical addition of conventional packing box is used, this non-adsorbed chemical is free in the supply to contaminate the other fiber streams and cause the processing problems previously described. Comparing the content of C-6092 of samples 2A and 3A, however, it is shown that only an additional 6% of the C-6092 retained was removed during the second drain step, which simulated leaf formation on a machine tissue.

When the C-6092 content of samples IB, 2B and 3B were compared it can be shown that 30% of the original 1.0% chemical load was removed during the first step d, but only an additional 7% of C-6092 retained was removed during the second drain step.

It is believed that this simulation of the improved chemical addition method demonstrates the ability to significantly reduce the amount of non-adsorbed chemical additive in the water of a papermaking process while maintaining chemical retention levels above the fiber fraction.

The above detailed description has been given for purposes of illustration. Therefore, a number of modifications and changes can be made without departing from the spirit and scope of the present invention. For example, the alternative or optional features described as part of an embodiment may be used to give yet another modality. Additionally, two named components can represent parts of the same structure. In addition, various alternate processes and equipment arrangements can be employed, particularly with respect to the preparation of supply, of the headbox, of the forming fabrics, of the tissue transfers, of the creping and drying. Therefore, the invention should not be limited by the specific embodiments described, but only by the claims and all equivalents thereof.

Claims (35)

R E I V I N D I C A C I O N S

1. A method comprising: creating a fiber solution comprising water, cellulosic fibers, and an adsorbable chemical additive; draining the fiber solution to remove the non-adsorbed chemical additive; Y redisperse the fibers with fresh water.

2. A method comprising: create a first fiber solution comprising water, cellulosic fibers, and an adsorbable chemical additive; create a second fiber solution that is essentially free of the adsorbable chemical additive; dewatering the first fiber solution to remove the non-adsorbed chemical additive; redispersing the fibers in the first fiber solution with fresh water; and forming a "paper product using a layered head box, the first fiber solution supplied to a first head box layer and the second fibr solution supplied to a second head box layer.

3. The method as claimed in clause 1, characterized in that the creation of the fiber solution comprises adding the adsorbable chemical additive to an aqueous solution comprising the water and the cellulose fibers.

4. The method as claimed in clauses 1 or 2, characterized in that the chemical additive is added to a solution of water and the cellulosic fibers in an amount of about 5 kilograms per metric ton or more.

5. The method as claimed in clauses 1 or 2, characterized in that the drainage increases the consistency of the fiber solution to about 30 per cent more.

6. The method as claimed in clauses 1 or 2, characterized in that the redispersing of the fiber decreases the consistency of the fiber solution to around d 5 percent or lower.

7. The method as claimed in clauses 1 or 2, further characterized in that it comprises and maintaining the non-adsorbed chemical additive separated from the fiber solution.

8. The method as claimed in clauses 1 or 2, characterized in that the fresh water is completely free of non-adsorbed chemical additive.

9. The method as claimed in clauses 1 or 2, characterized in that the sufficient residence time is provided after the chemical additive is added to allow adsorption.

10. The method as claimed in clauses 1 or 2, characterized in that the removed adsorbed chemical additive n is reused in the processing step before the drainage of the fiber solution.

11. The method as claimed in clauses 1 or 2, characterized in that the adsorbable chemical additive comprises an unglutinating agent.

12. The method as claimed in clauses 1 or 2, characterized in that the adsorbable chemical additive comprises a softening agent.

13. The method as claimed in clauses 1 or 2, characterized in that the chemical additive comprises a debinding agent or a softening agent and the fiber solution is not subjected to higher shear refining forces once the chemical additive is added to the product. fiber solution.

14. The method as claimed in clauses 1 or 2, characterized in that the redispersed fibr solution is treated with a second adsorbable chemical additive, drained a second time to remove the n adsorbed chemical additives and redispersed a second time.

15. The method as claimed in clause 14, characterized in that the second chemical additive comprises a softening agent.

* 16. The method as claimed in clause 14, characterized in that the second chemical additive comprises an unglutinating agent.

17. The method as claimed in clause 1, further characterized in that it comprises forming a paper product comprising a plurality of layers, with one, but not all, layers being formed from the fibr solution containing the adsorbable chemical additive. .

18. A method comprising: create a fiber solution comprising water cellulosic fibers, and a first adsorbable chemical additive; drain the fiber solution s. a consistency of around 20 percent or more; passing the dewatered fiber solution through a disperser to mechanically work the fibers; diluting the fiber solution with fresh water which is essentially free of the first chemical additive at a consistency of about 5 percent or less; adding a second adsorbable chemical additive comprising a debinding agent or a softening agent to the fiber solution; drain the fiber solution a. a consistency of around 20 percent or more; diluting the fiber solution with fresh water which is essentially free of the second chemical additive at a consistency of about 5 percent or less; and form a paper product for the fiber solution,

19. The method as claimed in clause 18, characterized in that the first chemical additive comprises a binder.

20. A supply of fiber produced using the described method as claimed in clause 1 characterized in that the amount of chemical additive adsorbed on the fibers is about 2 kilograms per metric ton or more, and the amount of non-adsorbed chemical additive is the water is within 0 and about 20 percent of the amount of chemical additive adsorbed on the fibers.

21. A fiber supply comprising water cellulosic fibers, and an adsorbable chemical additive, wherein the amount of chemical additive adsorbed on the fibers is about 2 kilograms per metric ton or more, and the amount of non-adsorbed chemical additive in the water is of entr 0 and about 20 percent of the amount of the chemical additive adsorbed on the fibers.

22. The supply of fiber as claimed in clauses 20 or 21, characterized in that the amount of chemical additive adsorbed on the fibers is d about 3 kilograms per metric ton or more.

23. The fiber supply as claimed in clause 22, characterized in that the amount of chemical additive adsorbed on the fibers is about kilograms per metric ton or more.

24. The fiber supply as claimed in clause 22, characterized in that the amount of chemical additive adsorbed on the fibers is about kilograms per metric ton or more.

25. The fiber supply as claimed in clauses 20 or 21, characterized in that the amount of chemical additive not adsorbed in the water is between 0 and about 15 percent of the amount of chemical additive adsorbed on the fibers.

26. The fiber supply as claimed in clause 25, characterized in that the amount of the chemical additive not adsorbed in the water is between about 10 percent of the amount of the chemical additive adsorbed on the fibers.

27. The fiber supply as claimed in clause 25, characterized in that the amount of chemical additive not adsorbed in the water is between 0 and about 7 percent of the amount of the chemical additive adsorbed on the fibers. -

28. The supply as claimed in clauses 20 or 21, characterized in that the chemical additive is selected from the group comprising softening agents, debinding agents, dry strength agents, wet strength agents and opacifying agents.

29. A paper product made from the ta supply and as claimed in clause 21.

30. A paper product made using the method as claimed in clause 1.

31. A paper product comprising a plurality of unit layers, the paper product made using the method as claimed in clause 2.

32. Such a paper product is claimed in clauses 29 or 30, characterized in that it has a chemical additive retention of about 4 kilograms per metric ton or more.

33. The paper product as claimed in clause 32, characterized in that it has a chemical additive retention of about 5 kilograms per metric ton or more.

34. The paper product as claimed in clause 31, characterized in that it comprises a central cap consisting essentially of soft wood fibers, two outer layers comprising about 70 percent more hardwood fibers.

35. The paper product as claimed in clauses 29 or 30, characterized in that the paper product is a layered tissue. E S U M E N Chemical additives can be adsorbed onto the fibers to make cellulosic paper at higher levels with a minimum amount of non-adsorbed chemical additives present in the process water to make paper. One method involves treating a fiber solution with an excess of the chemical additive leaving a sufficient residence time for the adsorption to occur, filtering the solution to remove the non-adsorbed chemical additives, and redispersing the filtered pulp with the fresh water. Filtration of the thickening process contains the non adsorbed chemical additive and it is not sent forward in the process with the chemically treated fibers.The method can be used to make improved paper products.