MXPA97000901A - Method for manufacturing soft tisu using silicones cationi - Google Patents

Abstract

The present invention relates to adding a relatively small amount of a cationic silicone to an aqueous suspension of fibers for making paper at the wet end of the tissue manufacturing process, providing improved tactility (softness) to the tissue.

Description

METHOD FOR MANUFACTURING TI8D 8DAVE OSANDO SILICONA8 CATIÓNICAS Background of the invention In the manufacture of soft tissues, such as facial tissues and sanitary ware, the industry has continuously improved the tactile characteristics of the product to meet the needs and desires of consumers. One means to improve the feeling of the tissues is to incorporate an additive into the tissue, including a silicone such as a polysiloxane. The term "silicone" includes a wide range of products having chains of silicon atoms as their core structure. Different properties are achieved by joining selected chemical functional groups to the silicone column. The resulting structures are commonly referred to as polysiloxane, polydimethylsiloxane, or polydiorganosiloxanes. Silicones are usually hydrophobic and can be obtained as clear fluids, organic solvent solutions, or as water emulsions. These emulsions can have a positive, neutral or negative charge. The size of the emulsion particle can also be adjusted from about 50 nanometers (micro-emulsions) to about one miera. The silicones can be supplied as a fluid, but these usually have a low solubility in water unless an additional functional group is used to add the hydrophilic character.

Silicones are known to provide a desirable silky or soft sensation to the surface of the tissue and thus improve the perceived softness. Silicones are typically applied to tissue tissue at some point after it is formed, either before or after drying, by spraying or printing the silicones on the surface of the tissue. Even when such methods are effective, they require a capital investment in the printing or spraying equipment to apply the silicone. Also, the silicones themselves are expensive and a significant amount of silicone is generally required to impart the desired properties to the tissue. Aggregate amounts typically range from about 1-2 percent by dry weight based on the weight of the fibers.

The concept of adding silicones to the wet end of the tissue manufacturing process has been previously considered due to its simplicity and the avoidance of capital investment in equipment. But when used in significant quantities such as those ordinarily required for spraying and printing, silicone creates a problem in the downstream creping operation by preventing adequate adhesion of the sheet to the drying surface and therefore causes the sheet Camp outside the dryer. In addition, silicone accumulates rapidly in the wet end water system, which must be discarded, resulting in the loss of expensive silicone.

There is therefore a need for means to incorporate the silicone materials into the tissues which improve the tissue's touch properties and which are simple and relatively cheap in terms of material and capital costs.

Synthesis of the invention It has now been discovered that silicones, particularly polysiloxanes, can be introduced into the wet end of the papermaking process at very low levels which are still effective in improving the softening of the resulting tissue product and which do not interfere with the tissue. the creping operation. This is achieved by using low levels of a silicone which binds to the negatively charged sites on the surface of the cellulose fibers through a cationic charge either on the silicone itself on the surfactant used to stabilize the particles colloidal. The creping adhesive formula can be adjusted accordingly to take into account the presence of the silicone at high silicone adhesion rates. The cationic bond can be achieved by contacting cellulose fibers with a compatible cationic silicone in water Water-soluble or a silicone which has been treated with a cationic surfactant to provide positive binding sites Such silicones bind to the cellulose fibers and exhibit a higher retention on the fiber than the non-ionic anionic silicones. As a result of this there is a significantly less loss of silicone in the white water system 5 during the formation of the tissue tissue and the silicone remained virtually in the fiber layer to which it was added. Est allows the production of a strong and soft tissue sheet.

Therefore, in one aspect, the invention resides in a / "Or method for making a soft tissue sheet comprising the steps of (a) forming an aqueous suspension of fibers to make cellulosic paper containing from about 0.01 to about 1 percent by dry weight, based on the weight of the fibers, of a cationic silicone; (b) deposit the fibr suspension aqueous on a foraminous forming wire which retains the fibers to form a wet tissue; (c) draining or draining / dry the wet tissue; (d) adhering the fabric to a creped cylinder, such as a Yankee dryer with the creping adhesive and (e) creping the fabric of the creping cylinder with a knife. of creping to form a soft tissue.

In the case of a wet-pressure process, the tissue can be dried on the Yankee dryer. In the case of a continuous drying process, the fabric can be dried partially or may be completely dried before being adhered to the creping cylinder, which again may be a Yankee drying. Alternatively, the fabric may be continuously dried and left uncolored if the cationic silicone and the fibers provide adequate softness without creping. Tale continuously dried tissues not creped preferably in layers and have at least one outer layer containing predominantly hardwood fibers and cationic silicone.

Preferably the tissue is formed as a tis in layers having a layer of hard wood on the side surface to the outside and a layer of soft wood (strength) on the inner surface. Since the cationic silicone in some aspects acts as a debonder, the silicone is preferably added only to the supply of hard wood outer layer to improve the softness of the resulting tissue if degrading the strength of the soft wood layer. In addition, it is preferred that the hardwood layer containing cationic silicone be placed against the surface of the creping cylinder or a Yankee dryer during creping so that the cationic silicone ends on the side of the tissue which is smoother and more soft. Generally, the "dryer side" of the tissue is smoother than the opposite side (air side). The final tissue product may have one, two, three or more layers. For multi-layer products, the individual layers are preferably of a two-layer construction, with the resistance layer positioned inwardly and the softer hardwood layer on the exterior side of the product.

Therefore in another aspect, the invention resides in a layered tissue sheet comprising a first layer and a second layer, wherein the first layer is an outer layer and contains predominantly hardwood fibers, such as eucalyptus fibers, and from about 0.01 to about 0.2 percent by dry weight, based on the weight of the fibers in the outer layer, of a cationic silicone, and wherein said second layer contains predominantly soft wood fibers.

As used herein, a "cationic silicone" is any polymer or silicone oligomer having a silicon column, including polysiloxanes, having a positive charge, either as a result of the silicone structure itself or as a result of being in combination with a surfactant. The silicone can be delivered to the aqueous suspension of fibers to make paper as a silicone fluid, an emulsion, a suspension, or a solid. The silicone can be unsubstituted polydi-ethylsiloxane or this can be a polysiloxane having substituted functional groups such as amino-, epoxy-, silanol-, quaternary nitrogen, etc.

For tis being creped, the amount of cationic silicone added to the aqueous suspension of the papermaking fibers can be from about 0.01 to about 1 percent by dry weight, more specifically from about 0.05 to about 0.5. by dry weight, and even more specifically from about 0.1 to about 0.2 percent by dry weight. The aggregate amount may depend on the desired tact properties, the fiber composition for making paper and the creping adhesive composition. If the cationic silicone is added to a layer, the above amounts are applied to the specific layer. If the tissue is mixed (not in layers) the above amounts are applied to the total weight of the tissue. For non-creped tissues, the upper limit on the amount of added cationic silicone may be higher, limited primarily by savings since there is no creping step with which the silicone may interfere.

If the silicone is combined with a surfactant, suitable surfactants include those surfactants that stabilize the emulsions of the desired silicone compounds. The specific structures of these surfactants can vary widely, but should have at least some cationic character.

With regard to the creping adhesive formulas useful for making creping tissues according to the method of this invention, suitable creping adhesives comprise an aqueous solution of a plasticizer (referred to herein as a "release agent") and a resin. thermoformable cationic polyamide, and preferably further comprises a polyvinyl alcohol. The creping adhesive is applied as a solution containing from about 0.1 to about 1 percent solids, the rest being water.

Suitable thermosetting cationic polyamide resins are the water-soluble polymeric reaction product of an epihalohydrin, and preferably epichlorohydrin, and water-soluble polyamide having secondary amine groups derived from polyalkylene polyamine and saturated aliphatic carboxylic dibasic carboxylic acid containing from about 3 to 10 carbon atoms. Water-soluble polyamide contains recurring groups of the formula: -NH (CnH2nHN) x-CORCO- wherein n and x are each 2 or more and R is a divalent hydrocarbon radical of the dibasic carboxylic acid. An important characteristic of these resins is that they are phase compatible with polyvinyl alcohol. Suitable materials of this type are commercially available under the trademark KYMENE® (Hercules, Inc.) and CASCAMID® (Borden) and are more fully described in United States Patent No. 2,926,116 issued to Gerald Keim on February 23. 1960, United States Patent No. 3,058,873 issued to Gerald Keim et al. on October 16, 1962 and United States Patent No. 4,528,316 issued to Dave Soerens on July 9, 1985, all of which they are incorporated here by reference. The creping adhesive also preferably includes the polyvinyl alcohol. The amount of the thermosetting cationic polyamide resin in the creping composition based on percent by weight solids, can be from about 10 to about 80 percent, more specifically from about 20 to about 60 percent. hundred.

Suitable plasticizers or release agents include the quaternized polyamino amides and sorbitol, even though the plasticizing mechanism of sorbitol is feasibly different from that of the quaternized polyamino amides. A preferred polyamino quaternized amide is Quaker 2008, commercially available from Quaker Chemical Company. A significant amount of this release agent must be included in the creping composition in order to prevent the tissue sheet from wrapping around the dryer and to virtually prevent the fibers from accumulating on the surface of the dryer. Suitable amounts of the release agents in the creping adhesive composition can be from about 10 to about 40 percent by weight, more specifically from about 15 to about 25 percent by weight, based on solid When present, the amount of polyvinyl alcohol can be from about 1 to about 80 percent by weight, more specifically from about 20 to about 60 percent by weight on a solids basis.

If the tissue is creped, the dryer temperature is such that the tissue is creped from the dryer surface as dry as possible. The temperature of the tissue tissue when it reaches the creping blade, as measured by an infrared temperature sensor, is about 200 degrees F or greater, preferably about 220 degrees F or greater, and more preferably about 100 degrees F. 235 degrees F. A suitable range is from about 225 degrees F to about 235 degrees F. At the same time, the moisture content of the fabric in the creping blade is about 3 percent or less, preferably 2.5 percent or less. An adequate range is from around 2 to 3 percent. These conditions provide very high adhesion of the fabric to the dryer surface and thus allow the creping blade to uniformly disengage the sheet.

Brief Description of the Drawing Figure 1 is a schematic flow chart of a process for making the tissue useful according to the invention, in which two tissues are individually formed and layered to form a fabric of layers.

Figure 2 is a schematic flow diagram of a process for making wet press tissue also useful in the practice of this invention, in which the layered tissue is formed using a layered headbox.

Figure 3 is a bar graph of the results of a study on the retention of various silicones by the fibers to make cellulosic paper, illustrating the greater retention of the cationic silicones. pr. Figure 4 is a bar graph of the results of the study of the hand sheet on the retention of silicones, illustrating the impact of silicones on the resistance of the leaves for hands. Figure 5 is a schematic graph of the amount of silicones against the amount of release agent in the creping adhesive formula, illustrating the window of operation available to balance the amounts of both chemicals.

Detailed Drawing Description Referring to Figure 1, there is disclosed a method for making a wet pressed tissue according to the invention, commonly referred to as layering, wherein two wet tissues are formed independently and then combined into a unitary fabric. To form the first fabric, a specified fiber (either softwood or hardwood) was prepared in a manner well known in the paper making arts and delivered to the first supply box 1, in which the fiber was maintained. in an aqueous suspension. A supply pump 2 delivers the required amount of suspension to the suction side of the fan pump 4. A metering pump 5 supplies a chemical such as a dry strength resin or silicone to the fiber suspension. The additional dilution water 3 is also mixed with the fiber suspension. The complete mixture is pressurized and delivered to the head box 6. The head box 6 leaves the aqueous suspension and is deposited on an endless paper cloth 7 on the suction box 8. The suction box is under vacuum which pulls the water out of the suspension, thus forming the first fabric. In this example, the supply coming out of the head box 6 will be referred to as the "air side" layer, that layer which will eventually be placed out of the surface of the dryer during drying.

The forming fabric may be any forming fabric, preferably having a fiber support index of about 150 or greater. Suitable specific forming fabrics include, without limitation, single layer fabrics, such as the Appleton Wire 94M available from Albany Internationa Corporation, Appleton Wire Division, Menasha Wisconsin; double layer fabrics such as Asten 866 available from Aste Group, of Appleton, Wisconsin; and triple layer fabrics, such as the Lindsay 3080, available from Lindsay Wire Florenc Mississippi.

The consistency of the aqueous suspension of the fibers to make paper leaving the head box can formars "" -0 of about 0.05 to about 2 percent, preferably about 0.2 percent. The cationic silicone may be added to the aqueous suspension of fibers to make paper at a point prior to tissue formation, such as in the supply box or in the raw material box. It is preferred that l The silicone is added to the supply layer which is placed against the surface of the dryer during creping, which in this case will be the layer leaving the second headbox 16. The cationic silicone is preferably added to the supply of hardwood fibers, which is used preferably to form one or both of the outer layers of the tissue. The first head box 6 can be a layered head box with two or more layer chambers that delivers a first layer or stratified wet fabric, or that can be a monolayer head box that delivers a first fabric. wet mixed or homogeneous.

To form the second fabric, a specified fiber (either hardwood or softwood) was prepared in a manner well known in the paper making arts and delivered to the second supply box 11, in which the fiber held in a suspension watery A supply pump provides the required amount of suspension to the suction side of the fan pump 14. A metering pump can alternatively supply chemicals such as the dry strength resin or the silicone inside the fiber suspension as described above. The additional dilution water is also mixed with the fiber suspension. The complete mix is then pressurized and delivered to the box 16. The aqueous suspension leaves the head box 16 and is placed on the endless paper fabric 17 on the suction box 18. The suction box 18 is under vacuum which leaves the water outside the suspension, thus forming the wet tissue. In this example, the supply coming out of head box 16 is referred to as the "dryer side" layer, that layer being in eventual contact with the surface of the dryer. The forming fabrics suitable for the forming fabric 17 of the second head box include those previously mentioned forming fabrics with respect to the first head box forming fabric.

After the initial formation of the first and second wet fabrics, the two fabrics are put together at a contact ratio while they are at a consistency of about 10 to about 30 percent. Whatever the selected consistency, it is preferred that the consistency of the two wet tissues be virtually identical. Layering is achieved by carrying the first wet fabric to contact the second wet fabric on the roll 19.

After the consolidated fabric has been transferred to the felt 22 in the vacuum box 20, the drainage, drying and creping of the consolidated fabric is achieved in a conventional manner. More specifically, the layered fabric is further dewatered and transferred to a Yankee dryer using a pressure roller 31 which serves to squeeze the water from the fabric, which is absorbed by the felt, and causes the fabric to adhere to the fabric. the surface of the Yankee. The fabric is then creped and rolled into a roll 32 for a subsequent conversion into the final creped product.

Figure 2 is a schematic flow chart of a wet-pressed tissue manufacturing process for use in accordance with this invention. A layered head box 41, a forming fabric 42, a formed roller 43, a papermaking felt 44, a pressure roller 45, a Yankee dryer 46, and a creping blade 47. Also shown but not numbered are the various loose tension rolls used to define the cloth runs in the schematic diagram, which may differ in practice. In operation, a layered head box 41 continuously deposited a layered supply jet between the forming fabric 42 the felt 44, which is partially wrapped around the forming roll 43. The water is removed from the aqueous supply suspension through of the forming fabric by centrifugal force to traverse the newly formed fabric of the forming roller. As the forming fabric and felt separate, the wet fabric remains on the felt and is transported to the dryer.

In the Yankee dryer, creped chemicals are applied continuously to the top of the existing adhesive in the form of an aqueous solution. The solution applied by convenient means, preferably using spray tube which evenly sprays the dryer surface with the creping adhesive solution. The application point on the surface of the dryer is immediately after the creping doctor blade allowing a sufficient time for the spreading and drying of the fresh adhesive film. The wet fabric is applied to the surface of the dryer by means of a pressure roller with an application force of about 200 pounds per square inch (psi). The incoming wet fabric is nominally around a 10 percent consistency (varying from from about to about 20 percent) to the moment it reaches the pressing knee. After the dewatering or pressing step, the consistency of the fabric is at or about 30 percent. A sufficient drying capacity of the cover and a sufficient steam strength of the dryer are applied to this fabric to reach a final moisture content of 3 percent or less preferably 2.5 percent or less. The temperature of the fabric sheet immediately preceding the creping blade is measured by an infrared temperature sensor, and preferably about 235 degrees F.

Figure 3 is a bar graph illustrating the retention of various types of silicones by cellulosic paper fibers as described in the hand sheet study described herein in example 1, illustrating a significantly higher retention of cationic silicones. . The percent of Soxhlet extractants is shown as a function of the particular silicone as identified by the silicone code. As indicated by the bar graph, the cationic silicones (1716 and 108) have significantly higher retention values than the other silicone tested.

Figure 4 is a bar graph showing and impact of the silicones described above on the strength and tension of the leaves for hands. The silicones with cationic emulsions and the higher Soxhlet extractants (1716 and 108) had the greatest impact on the tension of the hand sheet. The silicone 1716 had a 58 percent reduction in tensile strength. The non-ionic "DS" did not show a significant change in tension.

Figure 5 is a schematic graph showing the concentration of the cationic silicone in the fibers which makes contact with the creping cylinder as a function of the - * - 0 concentration of the release agent in the creping adhesive composition, illustrating the operation window (the shaded part under the curve) in which the creping function is effective. It is believed that cationic silicone functions as a release agent, necessitating adjustments to achieve a balancing action. suitable between the two chemicals. As shown, at high levels of cationic silicone adhesion, which is believed to be up to about 1 percent by dry weight based on the weight of the fibers to which the silicone was added, adequate creping can not be achieved no matter the amount of agent release in the creped adhesive formula. At lower levels of the cationic silicone adhesion, the area of the graph to the left of the operation window represents an area in which an adhesion is formed on the drying surface due to excessive adhesion. The area to the right of the operation window represents an area in which the sheet is flared out of the dryer due to inadequate adhesion.

As shown, at high levels of release agent the proper creping can not be achieved either. Even when the precise form of the operation window is not known, there is place under these limits to balance and optimize the amounts of the silicone 5 and the release agent.

Examples Example 1. j- * ~) A study of a hand sheet was carried out to evaluate the effect of the different silicones on the physical and tactile properties of various types of fibers (eucalyptus, dispersed eucalyptus, and maple BCTMP). In the preparation of the leaves for hands, a supply solution of 50 grams dry (g) of fiber and 1950 g of distilled water were prepared for each code. The solution was then placed in a British Pulp Disintegrator at 3000 revolutions per minute for 5 minutes. The resulting solution was made up to 8 liters with distilled water. A 0.5 percent active silicone solution was prepared and 1.81 percent by weight of active silicone, based on the weight of the fibers, was added to the solution. The mixture was allowed to settle for 10 minutes before proceeding. 450 milliliters of this solution were used well mixed to make an 8.5-inch by 8.5-inch hand sheet in a Valley Ironwork mold. The hand sheets were layered off the grid, placed on the press with blotter sheets, and pressed at a pressure of 75 pounds per square inch for one minute. They were dried on a steam dryer for two minutes, and finally dried in an oven at around 60-70 degrees centigrade at a constant weight (60 grams per square meter, completely dry). The leaves for hands were cut to 7.5 square inches. The hand sheets were then conditioned for at least 48 hours in a room kept at a constant relative humidity and at a constant temperature according to the TAPPI 402 standard. Ten standard hand sheets were produced for each code.

The hand-sheet study evaluated several different silicones: "DSW softener" was an epoxy-substituted polysiloxane in the form of a non-ionic aqueous emulsion having a pH of 7, available from Dow Corning, Midland, Michigan. "Q4-3667" was a copolymer silicone fluid, available from Dow Corning. The "Micro-Emulsion 1716" was a substituted polysiloxane emulsion of cationic silanol having a pH of 5.7, available from Dow Corning. "Emulsion 108" was an emulsion of cationic amino-substituted polysiloxane having a pH of 4.5-5.5, available from Dow Corning. "Emulsion E-677" was a non-ionic amino-substituted polysiloxane emulsion available from Wacker Silicones Corporation of Adrián, Michigan.

Changes in percent extractive (Figure 3) by Soxhlet extraction and tensile strength (Figure 4) indicate that the cationic emulsions, from Dow Corning "Emulsion 108" and "Micro Emulsion 1716w, were the best candidates to achieve a adequate retention in the wet extreao of the tissue machine This supports the retention mechanism requiring a difference in charge between the silicone emulsion (cationic) and the fiber (anionic).

To further evaluate various silicone materials for making a tissue, several prototypes of tissue were produced (Example 2-7) on a small scale continuous pilot machine configured as shown in Figure 1. This machine formed two separate sheets of tissue and He put them in layers together on a single sheet which was then pressed, dried and creped. This configuration allowed the simulation of a tissue sheet in I. layers with a very high layer purity. Each trainer had its own supply system including the supply chest, the dosing pump, the fan pump and the white water handling. This allowed each layer to have its own fiber mixture and an independent chemical treatment. Chemists can be added to the chest to create a single load at a concentration or dosed within the supply line to allow periodic adjustment.

Example 2 The "DSW Softener" from Dow Corning was added in an amount equivalent to 12 pounds / MT (0.54 percent) to the air side supply chest containing maple BCTMP at a consistency of approximately 0.8 percent. The dryer side supply chest contained a softwood kraft fiber from the north (LL19). A layered tissue sheet was produced containing 50 percent silicone-treated maple BCTMP and 50 percent untreated softwood.

The untreated soft wood was run on the side of the dryer. A dry strength starch (RediBond 2005 from National Starch and Chemical Company) was added to the supply pump on the softwood side to control the tensile strengths. The sheet of tissue was collected with hard wood on the side to the outside. Subsequent testing indicated that there was no tactile improvement compared to controls produced with 50 percent BCTMP from untreated maple and 50 percent kraft fiber from northern softwood.

Example 3 The "Q4-3667" from Dow Corning was added in an amount equivalent to 10 pounds / MT (0.45 percent) to the air side supply chest containing the dispersed eucalyptus fiber at a consistency of approximately 0.8 percent. The dryer side supply chest containing the soft wood fiber (LL19). A sheet of layered tissue was produced containing 50 percent dispersed eucalyptus treated with silicone and 50 percent untreated softwood. The untreated soft wood was run on the side of the dryer. A dry strength starch (RediBond 2005) was added to the supply pump on the softwood side to control the '' Or tensile strengths to the target The observations included an increase in the basis weight when the silicone was added This is an indirect indication that the silicone was retained in the sheet (Other cationic chemicals also create this effect when they are added first when operating charged molecules as a retention aid). The tissue sheet was folded with the hard wood on the side to the outside. Subsequent testing indicated a tactile improvement compared to controls produced with 50 percent untreated eucalyptus dispersed and 50 percent untreated softwood. twenty Example 4 The "Q4-3667" from Dow Corning was added in a amount equivalent to 10 pounds / MT (0.45 percent) to the dryer-side supply chest containing the eucalyptus fiber dispersed to a consistency of approximately 0.3 percent. The air side supply chest contained a soft wood fiber (LL19). One sheet of layered tissue was produced containing 50 percent dispersed eucalyptus treated with silicone and 50 percent untreated softwood. The treated hardwood was run on the side of the dryer. A dry strength starch (RediBond 2005) was added to the supply pump on the softwood side to control the tensile strengths to the target. There was a minor deterioration in crepe quality indicating that the silicone was present in the tissue. The tissue sheet was collected with the hard wood on the outer side. Subsequent tests indicate an improvement in touch compared to controls.

Example 5 The "Microemulsion 1716" from Dow Corning was added in an amount equivalent to 10 pounds / MT (0.45 percent) to the dryer-side supply chest containing the dispersed eucalyptus fiber at a consistency of approximately 0.8 percent. The air side supply chest contained a soft wood fiber (LL19). One sheet of layered tissue was produced containing 50 percent dispersed eucalyptus treated with silicone and 50 percent untreated softwood. A dry strength starch (RediBond 2005) was added to the supply pump on the softwood side to control the tensile strengths to the target. There was a minor deterioration in the crepe quality indicating that the silicone was present in the tissue. The sheet of tissue was collected with hard wood on the outside. Subsequent tests indicated an improvement in tact compared to the controls.

Example 6 The "Microemulsion 1716" from Dow Corning was added in an amount equivalent to 30 pounds / MT (1.36 percent) to the dryer-side delivery chest containing the eucalyptus fiber dispersed to a consistency of approximately 0.8 percent. The air side supply chest contained a soft wood fiber (LL19). One sheet of layered tissue was produced containing 50 percent dispersed eucalyptus treated with silicone and 50 percent untreated softwood. There was a rapid deterioration in crepe quality within a few minutes after the silicone was introduced into the delivery system. The resulting sheet did not possess crepe and had a stiff sheet very similar to a machine-glazed paper produced for other purposes. The absence of stretching precluded the conversion into a two-layer product.

Example 7. The "Emulsion 108" from Dow Corning was added in an amount equivalent to 10 pounds / MT (0.45 percent) to the dryer-side supply chest containing eucalyptus fiber dispersed to a consistency of about 0.8 percent. The air side supply chest containing a soft wood fiber (LL19). One sheet of layered tissue was produced containing 50 percent dispersed eucalyptus treated with silicone and 50 percent untreated softwood. The treated soft wood was run on the side of the dryer. A dry strength starch (RediBond 2005) was added to the supply pump on the softwood side to control the tensile strength to the target. At 10 pounds / MT, "Emulsion 108" resulted in a poor and eventual profile and in an uneven dryer coating after several rollers indicating that the silicone was present in the fabric. The tissue sheet was folded with the hard wood on the outside. Subsequent tests indicate an improvement in touch compared to controls.

The additional test of the addition of the silicone was carried out as described in Examples 8-14 using a growing former, a wet pressure machine as illustrated in Figure 2. For all the following Examples, an agent of Moisture resistance (Ky ene 557LX) was added to around 5 pounds per metric ton. It was equally divided between short and long fiber. The calculation of "pounds per metric ton" was based on the base weight of the entire sheet dryer even though in many cases the chemical was only added to a part of the sheet. In all cases, the silicone was cationic silicone (Emulsion 108 from Dow Corning).

Example 8 A silicone emulsion was added to a hardwood supply layer (dryer side layer) at 0.1 percent by dry weight based on the weight of fiber in the hardwood cap. The silicone was added to the bulk supply on a loading base before dilution before the headbox. A dry strength agent (Parez 631 available from American Cyanamid) was added to the soft mader supply layer (air side layer) at about 0.125 weight percent. The dry strength agent was added to a coarse supply on a continuous basis before dilution before the headbox. In this example, the dry strength agent was added at the same level as the control which did not contain silicone. The creping adhesive contained 40 percent polyvinyl alcohol, 40 percent Kymene 557LX 20 percent of a Quaker 2008 release agent, which was identical to the control. This tissue exhibited substantial improvements in tactile properties compared to control.

Example 9, The silicone was added as described in example 8, except at 0.08 percent by weight. The proportion of the creping adhesive composition was also changed to 45/45/10. The dry strength agent had to be increased to about 0.25 percent by weight because with less agent d release the creping blade did not run deep enough in the coating and the resistance degradation was greater. The softness did not improve greatly. The lack of better softness is believed to be due to the change in the creping adhesive composition coupled to the low silicone levels compared to Example 8.

Example 10 The silicone was added as described in Example 8, except at 0.32 percent by weight. The proportion of the creping adhesive composition was also changed to 80/20/0. The dry strength was increased to about 0.5 per cent by weight because without the release agent the creped blade did not run deep enough in the coating and the strength degradation was greater. The softness was slightly improved. The lack of an improvement of virtuous smoothness is believed to be due to the deviation of the optimal crepe conditions compared to Example 8. There was, however, enough silicone on the tissue to overcome the negative effects of undue creping.

Example 11 The silicone was added, as described in Example 8 to 0.16 percent by weight. The base weight of drying was reduced from 7.0 pounds per 2,880 square feet. (Example 8) 5.0 pounds per 2,880 square feet. The crepe adhesive composition ratio was changed 45/45/10. Dry strength was increased from 0.7 percent to 0.8 percent in comparison to the control. The softness was not greatly improved. The lack of improvement of softness is believed to depart from the optimum creping conditions, which are believed to be different for the 5 pound sheet used in this example compared to the 7 pound sheet used in the Example 8 Example 12 For this example, the long fiber and the short fiber were mixed before dilution before the headbox. Head box divider that normally separates the long and short fiber supply was left in place but it did not serve for a functional purpose. The dryer base weight was 5.0 pounds per 2,880 square feet compared to 7.0 in Example 8. Silica was added to the short fibers at 0.08 percent po weight before mixing with the long fibers. The dry strength agent was added to the long fiber at about 0.6 percent before mixing with the short fiber and compared to 0.5 percent for the control. The proportion of the creping adhesive composition was also changed to 45/45/10. The softness was improved, illustrating that the addition of cationic silicone can improve the smoothness of the mixed leaves (if layers).

Example 13 • '' O For this Example, long fiber and short fiber were mixed before dilution before the headbox.The divider that normally separates the short fiber and long fiber layers was left in place but did not A functional purpose The base weight of the dryer was 5.0 pounds per 2,880 square feet compared to 7.0 of Example 8. The silicone was added to the short fiber at 0.32 percent by weight before mixing with the long fiber. The dry strength was added to the long fiber at about 0.8 percent before mixing with the short fiber compared to 0.5 percent for the control. The proportion of the creping adhesive composition was also changed to 50/50/0. The softness was improved compared to Example 12. Increasing the addition of silicone resulted in improved smoothness even when the creping conditions had not been optimal. It will be appreciated that the foregoing Examples, given for purposes of illustration, should not be construed as limiting the scope of the invention, which is defined by the clauses that follow and all equivalents thereof. 5 20 25

Claims (12)

1. A method for making a soft tissue sheet comprising the steps of: a) forming an aqueous suspension of cellulosic paper fibers containing from about 0.01 to about 1 percent by dry weight, based on the weight of the fibers, of a cationic silicone; b) depositing the aqueous suspension on a foraminous forming wire that retains the fibers to form a wet fabric; c) draining or draining / drying the wet tissue; d) adhering the fabric to a creping cylinder with a creping adhesive; Y e) creping the fabric of the creping cylinder with a creping blade to form a soft tissue.

2. The method as claimed in clause 1 characterized in that the amount of cationic silicone is from about 0.05 to about 0.5 percent by dry weight.

3. The method as claimed in clause 1 characterized in that the amount of cationic silicone is from about 0.1 to about 0.2 percent by dry weight.

4. The method as claimed in clause 1 characterized in that the creping adhesive comprises from about 20 to about 60 percent by dry weight of polyvinyl alcohol, from about 20 to about 60 percent by dry weight of a thermosetting cationic polyamide resin, and from about 15 to about 25 weight percent of a quaternized polyamino amide release agent.

5. The method as claimed in clause 1 characterized in that the fabric is dried at a moisture content of about 3 percent less in the creping blade.

6. The method as claimed in clause 1 characterized in that the fibers for making paper are hardwood fibers which are subsequently deposited on the forming wire as an outer layer of tissue tissue.

7. The method as claimed in clause 6 characterized in that the hardwood layer is placed against the surface of the creping cylinder during creping.

8. The method as claimed in clause 1 characterized in that the silicone is a polysiloxane.

9. The method as claimed in clause 1 characterized in that the wet fabric is dewatered by wet pressure and adhered to a Yankee dryer.

10. The method as claimed in clause 1 characterized in that the wet fabric is continuously dried and then adhered to a creping cylinder.

11. A sheet of soft tissue containing from about 0.01 to about 1 percent by weight of a cationic silicone.

12. A layered tissue sheet comprising a first layer and a second layer, wherein the first layer is an outer layer and contains predominantly soft wood fibers and from about 0.01 to about 1 percent by weight of a cationic silicone , and where the second layer contains predominantly soft wood fibers.