MXPA98000416A - Method for creating tissue fabrics containing a softener using a closing creaming bag - Google Patents

Abstract

The present invention relates to soft tissue products that result from the presence of a debonding / softening agent in the outer layers of the tissue and creped under "closed" bag conditions. The desuperiorizing / softening agents belong to a group of organic chemicals that include various quaternary imidazolinium compounds. These chemicals do not interfere adversely with the adhesion, unlike most of the debonders, to the drying surface of the tissue machine. These can therefore be placed on the outer layers of the tissue which contact the dryer surface and improve creping. The tea can then be creped out of the drying surface using a closed bag, which is a bag angle of less than 80 degrees. Closed bag creping usually produces a dense and thicker tissue but with a crepépero. Closed bag creping and the presence of most of the debonders in the side-to-dryer layers would be expected to produce crepe-like structures as well. However, the interaction of the disintegrating adhesive properties and the closed bag creping conditions produce a bulky tissue with a crepefin structure sufficiently that it results in a general softness to the

Description

METHOD FOR CREATING TISSUE FABRICS CONTAINING A SOFTENER USING A CLOSED CREAMING BAG Background of the Invention The use of detaching / softening agents in facial and bath tissues is a common practice in the industry. It has been shown that adding such chemicals to the wet end of a tissue machine reduces adhesion to the drying surface. Soerens et al. In U.S. Patent No. 4,795,530 teaches that quaternary amines interfere with the adhesive / release combination normally employed for proper adhesion prior to the drying and creping process. Oriaran et al. In U.S. Patent No. 5,399,241 teaches that these same chemicals cause running problems by circulating in the white water system. Both of the aforementioned patents teach that it is a method to avoid these problems by spraying such chemicals onto the sheet after the cloth is formed and partially dried. It is our experience that softening agents soften by interfering with fiber-to-fiber bonding. It is also our experience that most softening agents reduce dryer adhesion as described by Soerens and Oriaran. Reduced adhesion results in less efficient blade breakage and rougher creping.

This reduction in leaf breakage as demonstrated by the rougher creping decreases the total softness of the tissue, which is contrary to the purpose for which the softener was added.

It has also been shown that thin creping and soft tissue result from crepe bag angles of between 80 and 90 degrees. U.S. Patent No. 4,300,981 issued to Carstens shows this in his examples. Angles less than 80 degrees are considered "closed" and are known to reduce leaf breakage if adhesion is not increased. This also results in the generation of a rough crepe.

Synthesis of the Invention It has now been discovered that a particularly soft tissue can be produced using a closed creping bag if the appropriate softening agent is used. More specifically, this invention allows the wet end adhesion of certain softening agents which do not interfere adversely with the adhesion of the tissue to the drying surface coated with the creping adhesive. Due to the chemical nature of the softeners used in this invention, a creped tissue having a combination of low density and surface smoothness can be achieved. The low density is derived from the closed bag creping and the surface smoothness is derived from the proper adhesion to the drying surface.

Therefore, in one aspect, the invention resides in a method for creping a dry tissue fabric comprising: (a) spraying a creping adhesive onto the surface of a rotating creping cylinder (Yankee dryer), said creping adhesive comprises a mixture of an aqueous polyamide resin and a cationic oligomer, such as a quaternized amine polyamide; (b) adhering the tissue to the surface of the creping cylinder, said tissue contains an imidazolinium quaternary compound having the following structural formula: wherein X = methyl sulfate or any other compatible anion; Y R = C8 - C22 # saturated or unsaturated, normal, aliphatic; and (c) dislodging the tissue from the creping cylinder by contacting it with a doctor blade placed against the creping cylinder surface and presenting the fabric with a creping bag angle of about 78 degrees. or less, more specifically from about 70 degrees to 78 degrees, and even more specifically from about 75 degrees to 78 degrees, said tissue has a moisture content of about 2.5 percent by weight or less before contact the doctor blade.

In another aspect, the invention resides in a tissue made by the method described above.

The creping adhesive useful for the purposes of this invention comprises a mixture of an aqueous polyamide resin and a cationic oligomer, such as a quaternized amine polyamide. The amount of the polyamide resin in the creping adhesive formula can be from about 10 to about 80 percent by dry weight, more particularly from about 20 to about 40 percent by dry weight. The amount of the cationic oligomer in the creping adhesive formula can be from about 5 to about 50 percent by dry weight, more specifically from about 10 to about 30 percent by dry weight. Optionally, the creping adhesive may further comprise a polyvinyl alcohol, suitably in an amount of from about 20 to about 80 percent by dry weight, and more particularly from about 40 to about 60 percent by dry weight.

Suitable aqueous polyamide resins are thermosetting cationic polyamide resins as described in U.S. Patent No. 4,528,316 issued July 9, 1985 to Soerens and entitled "Creping Adhesives Containing Polyvinyl Alcohol and Cationic Polyamide Resins" , which is incorporated herein by reference. The polyamide resin component of the creping adhesive comprises a water-soluble polymeric reaction product of an epihalohydrin, preferably epirohydrin, and a water-soluble polyamide having secondary amine groups derived from a polyalkylene polyamide and a saturated aliphatic dibasic carboxylic acid which contains from about 3 to about 10 carbon atoms. Water-soluble polyamide reagents contain recurring groups of the formula HICnH ^ HN), --CORCO- where n and x are each two or more and R is the divalent hydrocarbon radical of the dibasic carboxylic acid. An essential characteristic of the resulting cationic polyamide resins is that they are phase compatible with the polyvinyl alcohol in the creping adhesive; for example, these do not separate phase in the presence of aqueous polyvinyl alcohol.

The preparation of the polyamide resin component useful for the purposes of this invention is described more fully in U.S. Patent No. 2,926,116 issued to Gerald I. Keim on February 23, 1960, and the U.S. Patent. of North America number 3,058,873 issued to Gerald I. Keim et al., October 16, 1962, both of which are incorporated herein by reference. Although both of these patents teach only the use of epirohydrin as the reagent with the polyamide, any epihalohydrin is believed to be useful for the purposes of the invention since all epihalohydrins must give a cationic active form of the polyamide resin to the polyamide resin. Suitable pH when reacted with the secondary amine groups of the polyamide.

Suitable commercially available aqueous polyamide resins include Ky ene 557 LX (from Hercules, Inc.), Quacoat A252 (from Quaker Chemical), and Unisoft 803 (from Houghton International), Crepeplus 97 (from Hercules, Inc.), and Cascamid (from Borden).

Suitable commercially available quaternized polyamide amines include Quaker 2008M (ex Quaker Chemical).

The quaternary imidazolinium compound or compounds can be added to the tissue manufacturing process at any point before the creping blade, but are preferably added at the wet end, more preferably they are added to the thick supply prior to the formation of the fabric where The consistency of the fiber suspension for making aqueous paper is around 2 percent or more. The quaternary imidazolinium compound can be added to the fiber suspension to make paper from a mixed tissue (without layers) or to a layered tissue. If it is layered, it is preferred to add the quaternary imidazolinium compound to the supply of the layer which finally has contact with the surface £ of the creping cylinder. In most cases this is also the layer facing away from the final tissue product that makes contact with the consumer.

The amount of imidazolinium quaternary ammonium compound in the tissue can be any amount, more specifically from about 0.5 to about 0.5 percent by dry weight based on the dry weight of the fiber in the finished product. The smaller amounts are less effective in providing adequate softness. Larger amounts are less economically attractive.

Suitable imidazolinium quaternary compounds include Varisoft 3690 (commercially available from Witco Corporation) and DPSC 5299-8 (from Witco Corporation), which is a quaternary imidazolinium mixed with a fatty acid alkoxylate and a polyether with 200-300 molecular weight.

In addition to the quaternary imidazolinium compound, the nonionic surfactants can also be added to the tissue at the wet end of the tissue manufacturing process to further improve the smoothness of the final product. Examples of the useful classes of the nonionic surfactants include the alkylphenol ethoxylates; the aliphatic alcohol ethoxylates (the alkyl chain of the aliphatic alcohol can be either straight or branched, primary or secondary); the fatty acid alkoxylates (the? fatty acids can be saturated or unsaturated); the fatty alcohol alkoxylates; the block copolymers of ethylene oxide and propylene oxide; the condensation products of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine; the condensation products of propylene oxide with the reaction product of ethylene oxide and ethylene diamine; semi-polar non-ionic surfactants, including water-soluble amine oxides; the alkylpolysaccharides, including alkyl polyglycosides; and the fatty acid amide surfactants. Particularly useful nonionic surfactants are the silicone glycols having the following structural formula wherein R = C, - C8, alkyl group; R, = acetate group or hydroxyl group; x = 1 to 1, 000; y = 1 to 50; m = 1 to 30; Y '"n = 1 to 30.

The amount of silicone glycol added to the wet end can be any effective amount to increase the softness of the tissue, more specifically from about 0.0005 to about 3 percent by dry weight based on the amount of fiber in the finished tissue, and still more specifically from about 0.005 to about 1 percent by dry weight.

In combination with silicone glycol and other nonionic surfactants, polyhydroxy compounds can also be advantageously included. Examples of useful polyhydroxy compounds include glycerol, and polyethylene glycols and polypropylene glycols having a weight average molecular weight of from about 200 to about 4,000, preferably from about 200 to about 1,000, more preferably from about 200 to about 600. Polyethylene glycols having a weight average molecular weight of from about 200 to about 600 are especially preferred.

The moisture content of the dried tissue fabric before contacting the doctor blade can be about 2.5 percent or less, more specifically about 2.0 percent or less, and even more specifically from about 2.0. to around 2.5 percent. The tissue fabrics to be creped according to the creping method of this invention can be wet compressed or can be continuous drying tissue fabrics. In both cases, it is preferable that the creping cylinder be a Yankee dryer, which dries the final fabric at the desired moisture level before setting.

Dry strength moisture additives can also be used within the scope of the present invention. Suitable dry strength agents include, without limitation, polyacrylamide resins and carboxymethyl cellulose. Suitable wet strength additives include both temporary and permanent wet strength additives. Suitable wet strength additives include, without limitation, urea-for-aldehyde resins, melamine-formaldehyde resins, epoxidized resins, polyamine-polyamide-epichlorohydrin resins, glyoxalated polyacrylamide quenches, polyethyleneimine resins, dialdehyde starch, starch cathodic aldehyde, cellulose xanthose, synthetic latexes, glyoxal acrylic emulsions, and amphoteric starch siloxanes.

Brief Description of the Drawings Figure 1 is a schematic diagram of a layered tissue forming process useful for the purposes of this invention.

Figure 2 is a schematic flow diagram of a tissue making process useful in carrying out the method of this invention.

Figure 3 is a schematic representation of the creping bag illustrating the creping geometry.

Figure 4 is a schematic of an optical surface creping analysis of different tissue products comparing the crepe structure of the products of this invention with the products of the prior art.

Figure 5 is a schematic representation of the apparatus used to measure the creping structure of the tissues to generate the data drawn in Figure 4.

Detailed Description of the Drawings Figure 1 is a schematic diagram of a layered forming process illustrating the sequence of layer formation. Also shown is a head box one of two layers containing a head box layer divider 2 separating the first supply layer (the bottom or bottom layer) from the second supply layer (the top layer). The two supply layers each consist of a dilute aqueous suspension of papermaking fibers which have different consistencies. In general, the consistencies of these supply layers will be around 0.04 percent to about 1 percent. An endless moving fabric 3 adequately supported and driven by rollers 4 and 5, receives the supply for making paper in layers that leaves the headbox and stops the fibers on it while allowing some of the water to pass. as shown by arrow 6. In practice, water removal is achieved by combinations of gravity, centrifugal force, and vacuum suction depending on the forming configuration. As shown, the first supply layer is the supply layer which first makes contact with the forming fabric. The second supply layer (and any successive supply layers if a headbox having more than one divider is used) is the second formed layer and is formed on top of the first layer. As shown, the second supply layer never makes contact with the forming fabric As a result of this, the water in the second and in any successive layers must pass through the first layer in order to be removed from the fabric. While passing through the forming fabric, even though this situation can be considered as disruptive to the formation of the first layer because all the additional water is deposited on the first supply layer fabric, it provides substantial improvements in the formation of the Second and successive layers without detriment to the formation of the first layer The softening agent is typically added to the thick supply before it is diluted.The supply layer to which the agent is added is typically that which makes contact with the surface of drying.

Figure 2 is a schematic flow chart of the conventional tissue manufacturing process. The specific illustrated training mode is commonly mentioned as a growing training. A layered headbox 21, a forming fabric 22, a forming roller 23, a papermaking felt 24, a compression roller 25, a Yankee dryer 26 and a creping blade 27 are shown. Also shown, but they are not numbered, several tension or loose rolls used to define the cloth runs in the schematic diagram which may differ in practice. As shown, a layered headbox 21 continuously deposits a supply jet in layers between forging cloth 22. and felt 24, which is partially wrapped around the formed roll 23. Water is removed from the aqueous supply slurry through the forming fabric by means of centrifugal force as the newly formed fabric passes through the forming roll arc. As the forming fabric and felt separate, the wet fabric remains with the felt and is transported to the Yankee dryer 26.

In the Yankee dryer, the creping chemicals are applied continuously on top of the adhesive, subtracting after creping in the form of an aqueous solution.

The solution is applied by any convenient means, preferably using a spray device which evenly sprays the surface of the dryer with the creping adhesive solution. The point of application on the surface of the dryer is immediately after the creping doctor 27, allowing sufficient time for the spreading and drying of the fresh adhesive film.

The wet cloth is applied to the surface of the dryer by means of a compression roller with an application force of about 200 pounds per square inch (psi). The incoming wet fabric is nominally of a consistency of about 10 percent (varying from about 8 to about 20 percent) by the time it reaches the pressure roller. After the drainage or compression step, the consistency of the fabric is at or about 30 percent. Sufficient Yankee dryer steam and cover drying capacity are applied to this fabric to achieve a final moisture content of 3 percent or less, preferably 2.5 percent or less. The temperature sheet or cloth immediately preceding the creping blade, as measured by an infrared temperature sensor with a sensitivity of about 0.95, is preferably around 235 degrees F.

Figure 3 is a schematic view of the creping operation, illustrating the creping geometry. The creping bag, or bag angle, is formed by the angle of a tangent to the yankee and at the point of contact with the doctor blade and the surface of the doctor blade against which the blade reaches. The creping bag angle is schematically indicated by the double arrow and is commonly 80 to 90 degrees. The lower angles cause more energy to be transferred to the tissue / adhesive sandwich. However, unless the adhesion is adequate, the increased energy will cause a failure in the fabric / adhesive interface resulting in the bending of the sheet (as demonstrated by the rough crepe) rather than a compressive detachment will remain a sheet less dense which therefore will be softer. Unexpectedly, the proper adhesion of this invention allows the increased energy derived from the closed bag creping to result in a failure in the adhesive layer itself. This allows the sheet to be disjoined compressively, giving a smoother and less dense sheet.

The creping that results from this invention is not rougher as is usually seen with closed bag creping. However, it is also not as fine as described in the prior art as measured by a surface profilometer. In fact, this crepe structure is a combination of both rough and thin structures. What is seen when the product of this invention is observed is a fine crepe structure over imposed on the underlying rough crepe structure. Therefore, the fine structure confirms the effective breaking of the sheet while the underlying rough structure improves the perception of substance. Surface profilometer measurements of the prior art of the products of this invention will place the products of this invention out of the range of fine crepe and a soft tissue would not be expected.

Figure 4 shows the results of the optical surface creping measurements, which have been shown to correlate with the surface profilometry, confirming the differences between the examples of this invention (hereinafter described) and the tissues of the prior art are as described in the Carstens patent mentioned above. The optical surface crepe test provides an account of crepe fold height as well as the distance between the crepe valleys. The production of the test is an average crepe height and average distance between the crepe valleys. The production also shows the distribution of the account in various size ranges. The total count of peak heights greater than 68.29 microns is shown in Figure 4. Surprisingly, a consumer view and a management study showed that the tissue of Example 1 was preferred over softness to the prior art tissue 2 by a margin of 63 percent to 37 percent. This difference is significant at or above the 95 percent confidence level. Clearly fine crepe is not a prerequisite for soft tissue.

Figure 5 is a schematic representation of the apparatus used to measure the crepe structure as will be described below. The collimated light source is shown (slide projector) which projects the light at an angle of degrees outside the object plane. The prepared tissue sample is placed flat on the top of the table with the crepe pattern aligned at a 90 degree angle to the light source, resulting in shadows projected by the crepe folds as illustrated by the lines dotted The reflected light is seen and analyzed by the camera Quanti et having 50 mm lenses.

To measure the optical surface crepe using the set described in Figure 5, samples of wrinkle-free tissue are mounted on 10-by-12-inch glass plates by adhering them with SCOTCH® tape at the corners, and pulling the tissue under. a soft tension. A layer is used for the bath; Two layers (stratum) are used for the facial. A 5-by-5-inch patch of tissue was "painted" with a 2/3: 1/3 mixture of PENTEL® correction fluid and isopropyl alcohol, using a high-quality camel hair brush and applying only one address. A drying time of 20 minutes is sufficient.

The glass plates with the painted tissue are placed on the automacrostage (12 by 12 inch DCI) of a Cambridge Quantimet 900 image analyzer system, under the optical axis of a 50 mm El-Nikkor lens. The sample is illuminated at 30 degrees with a slide projector to form shadows. The program routine "OCREP5" (which is established below) is run to carry out the analysis. Exact shading correction and system calibration are carried out first. A two-histogram print is typically obtained after 15 fields of view of a centimeter are analyzed. The first histogram of peak heights. The second histogram measures the distances of the valleys.

Quantimet 900 Program Cambridge Instruments QUANTIMET 900 QUIPS: V03.02 USER: ROUTINE: OCREP5 DATE: RUNNING: 0 SPECIMEN: NAME OCREP5 DO: Optical crepe analysis providing two histograms: one on PICO HT; the other on the distance from PEAK TO PEAK.

AUTH = DATE = COND = Camb. Macrovisor: Automacrostage; 50 mm EL glasses - NIKKOR at f / 4; Posn pole = 42.2 cm (check focus); Bell and Howell slide projector, 5 seats up to placement 30 des; 1/8"Posterbd on glass sts; sample of 7 x 9" painted with PENTEL 2/3 + 1/3 ISOPROPANOL, curb on glass of 5-inch plate between the macrovisor and the table. Lenses B & H to the object plane focus point. Working Distance = 3 'with a 40 mm extension tube, providing a field size (LIVE CHART Max) = 11.6 x 9.09 mm.

Meter specimen identity.

Examine (No. 2 Newvicon LV = 0.00 SENS = 1.64, Load Shading Corrector.

Calibrate Use Specified (Calibration Value = 14.54 micras per pixel) STANDARD CALL DO NOT NO = 18 TANTHETA: = 0 TANTHETA: = 0.57725 LFRAMECNT: = 0 TOTSCANL: = 0 Analysis Phase (origin of exam 15000.0 25000.0 field size 2000 2000 number of fields 5 3 Detect 2D (more Obscure than 24 PAUSE) For FIELD FRAMEPOSX: FRAMEPOSY: XPOS: = 70 YPOS: = 50 Examiner (No. 2 Ne vicon AUTO- SENSIBILITY LV = 0.00) The Living Table is a multiple rectangle (X: 48, Y: 36,: 800, H: 128) The Picture Box is a multiple rectangle (X: XPOS, Y: YP0S, W: 750, H: 10) Detect 2D (more Obscure than 24) Modify (OPEN by 2) Modify (DILATE by 1-Vertically) Measure feature area FERET 0 FERET 90 in fix feature (of 700 features and 4 parameters) CHARACTERISTICS CALC: = TANTHETA * AREA / FERET 90 Distribution of ACCOUNT and CALC of CHARACTERISTICS in HISTO 1 from 20.00 to 2000.0 in 15 bins (LOG) Modify (SKELETON - Sub mode = Peel end) Modify (DILATE by 10 - Vertically) Transfer image from Invert A to Binary Production) Measure feature FERET AREA 0 FERET 90 in feature set (of 600 features and 4 parameters) CALC FEATURE: = AREA / FERET 90 ACCOUNT and CALC distribution of the CHARACTERISTICS in HISTO 2 from 50.00 to 2000.00 in 15 bins (LOG) LFRAMCNT: = LFRAMECNT + 1.

Step of Phase Next FIELD TOTSCANL: = NO * LFRAMECNT * CAL. CONST * I: FRAM: R / 10000.

Print "" Print "PICO HEIGHT PROGRAM (UM)" Print Distribution (HIST01, differential, bar scheme, 0.00 scale) To print To print " " Print (VALLEY DISTANCE HISTOGRAM (UM) Print Distribution (HIST02, differential, bar scheme, 0.00 scale) To print " " Print "TOTAL FIELDS =", FIELD NUMBER, "TOT SCA LENG (cm) = 'TOTSCANL for LOOPCOUNT = 1 to 6 To print Following End of the Program E 1 e p l o s The employment A soft tissue product was made using a layered headbox as illustrated in Figure 1 and using the general process of Figure 2. The first supply layer contained eucalyptus hardwood fiber which constituted up to 60 percent of the leaf by weight. This layer is the first layer to contact the forming fabric. Because it is transferred to the carrier felt, this is also the layer that contacts the dryer surface. The second supply layer contained soft northern wood kraft. This constituted up to 40 percent of the leaf by weight. An imidazolinium softener agent (methyl-1-oleyl amidoethyl-2-oleyl imidazolino methyl sulfate, identified as Varisoft 3690, commercially available from Witco Corporation) was added as a mixture with water at 4 percent solids. The addition was 0.2 percent of the fiber in the entire sheet. The addition was made to the thick supply of eucalyptus, which was at 2.25 percent solids. The base weight of the blade was 7.3 pounds per 2880 square feet of air-dried tissue. A moisture / dry strength agent, Parez 631 NC commercially available from Cytec Industries, Inc., was added to the soft wood layer as a 6 percent mixture with water. The addition rate was 0.9 percent of the fiber in the entire sheet.

This was added to the thick supply which was at 1.14 percent solids. The sheet was formed on a multilayer polyester fabric with a Fiber Support Index of 261. The Fiber Support Index is a measurement described by RL Beran in "The Evaluation and Selection of Fabric Formers" TAPPI, 62 ( 4), page 39 (1979). This was transferred to a conventional wet compression carrier felt. The water content of the sheet on the felt just before the transfer to the Yankee dryer was about 88 percent. The sheet was transferred to the Yankee dryer with a vacuum pressure roller. The clamping pressure was around 230 pounds per square inch and an equalized void of 5.5 inches per Mercury. The leaf moisture after the pressure roller was around 53 percent. The adhesive mixture sprayed onto the surface of the Yankee just before the compression roller consisted of 40 percent polyvinyl alcohol, 40 percent polyamide resin and 20 percent quaternized polyamide amine. The spray application rate was around 5.5 pounds of dry adhesive per metric ton of dry fiber. The creping bag angle was 78 degrees. A heated deck of natural gas partially around the Yankee had a supply air temperature of 533 degrees F to aid in drying. Leaf moisture after the creping blade was around 2.5 percent, the blade machine speed 24 inches wide was 3,000 feet per minute. The crepe ratio was 1.30 or 30 percent. This tissue was applied and calendered with two steel rollers at 20 pounds per linear inch. The product of two layers had the dryer / softener layer applied to the exterior side. The finished basis weight of the two-layer tissue at the standard temperature and in the TAPPI unit was 17.1 pounds per 2,880 square feet. The MD tension was 9126 grams per 3 inches and the DC tension was 461 grams per 3 inches. The thickness of a two-layer tissue was 0.0097 inches. The stretch of the machine direction in the finished tissue was 20.8 percent. All stress tests were in TAPPI conditions. The crepe value of optical surface (number of crepe peak heights greater than 68.29 micras) was 1,802.

Example 2 This product was made using a layered head box. The first supply layer contained hardwood fiber of eucalyptus. This constituted 60 percent of the leaf by weight. This layer is the first layer to contact the forming fabric. Because it is transferred to the carrier felt, this is also the layer that contacts the drying surface. The second supply layer contained soft northern wood kraft. This constituted up to 40 percent of the leaf by weight. A softening agent of imidazoline (quaternary imidazolinium, fatty acid alkoxylate and polyether with 200-800 molecular weight identified as DPSC-5299-8, produced by Witco Corporation) was added as a mixture with water at 4 percent solids. The addition rate was 0.17 percent of the fiber in the complete sheet. The addition was made to the thick supply of eucalyptus, which was at 2.25 percent solids. The base weight of the blade was 7.3 pounds per 2,880 square feet of air-dried tissue. A dry / wet strength agent, Parez 631 NC was added to the soft wood layer as a 1 percent mixture with water. The addition rate was 0.06 percent of the fiber in the complete sheet. This was added to the thick supply which was at 1.14 percent solids. The thick supply of the soft wood layer was also passed through a disk refiner before the addition of Pare.z .631 NC. The refiner's workload was 1.41 horsepower-days per metric ton of dry fiber. The eucalyptus layer contained a moisture resistance agent, Kymene 557LX commercially available from Hercules, Inc., added at 1.2 pounds per metric ton dry fiber in the entire sheet. The softwood layer contained a moisture resistance agent, Kymene 557LX, added at 2.3 pounds per metric ton dry fiber on the entire sheet. The sheet was formed on a multilayer polyester fabric with a fiber support index of 241. This was transformed into a conventional wet press carrier felt. The water content of the sheet on the felt just before the transfer to the Yankee dryer was about 88 percent. The sheet was transferred to the Yankee dryer with a vacuum pressure roller. The clamping point pressure was around 285 pounds per square inch and the vacuum equaled 5.5 inches of Mercury. The leaf moisture after the compression roll was around 53 percent. The adhesive mixture sprayed onto the Yankee surface just before the compression roll consisted of 50 percent polyamide resin and 50 percent quaternized amine polyamide. The application rate sprayed was around 3.9 pounds of dry adhesive per ton of dry fiber. The creping bag angle was 78 degrees. A heated deck of natural gas partially around the Yankee had a supply air temperature of 675 degrees F. to aid in drying. The leaf moisture after the creping blade was around 2.5 percent. The speed of the sheet machine 24 inches wide was 3,000 feet per minute. The crepe ratio was 1.30 or 30 percent. This tissue was folded together and calendered with two steel rollers at 20 pounds per linear inch. The product of two layers had the dryer / softener layer folded to the outside. The base weight of tissue delivery of two strata at room temperature and humidity was 16.9 pounds per 2,880 square feet. The MD tension was 919 grams per 3 inches and the DC tension was 490 grams per 3 inches. The thickness of a two-layer tissue was 0.0097 inches. The MD stretch in the finished tissue was 21.9 percent.

The optical surface crepe value was 2908 Employ This product was made using a layered head box. The first supply layer contained hardwood fiber of eucalyptus. This was made from 60 percent of the leaf by weight. This layer was the first layer to contact the forming fabric. Because it was transferred to the carrier felt, this is also the layer that contacts the dryer surface. The second supply layer contained soft northern wood kraft. This was made from 40 percent of the leaf by weight. An agent of. Softening of -imidazoline (Varisoft 3690) was added as a mixture with water and glycol silicone at 5 percent solids. Silicone glycol is available from Dow Corning Corporation as Dow Corning 190. By weight, the blend was 4 percent varisoft 3690 and 1 percent Dow Corning 190. The addition rate was 0.17 percent of the fiber in the full sheet The addition was made to the thick supply of eucalyptus, which was 2.25 percent solids. The base weight of the blade was 7.3 pounds per 2,880 square feet of air-dried tissue. A Parez 631 NC wet / dry strength agent was added to the soft wood layer as a 1 percent mixture with water. The addition rate was 0.07 percent of the fiber in the complete sheet. This was added to the thick supply which was at 1.14 percent solids. The thick supply of the soft wood layer was also passed through a disc refiner before the addition of Parez 631 NC. The refiner's workload was 1.43 horsepower days per metric ton of the drying fiber. The eucalyptus layer contained a wet strength agent, Kymene 557LX, which was added to 1.2 pounds per metric ton of dry fiber in the whole leaf. The softwood layer contained a moisture resistance agent, Kymene 557LX, added at 2.3 pounds per metric ton dry fiber on the entire sheet. The sheet was formed on a multi-layer polyester fabric with a fiber support index of 241. This was transformed into a conventional wet press carrier felt. The water content of the sheet on the felt just before the transfer to the Yankee dryer was about 88 percent. The sheet was transferred to the Yankee dryer with a vacuum compression roller. The clamping point pressure was around 285 pounds per square inch and the vacuum equaled 5.5 inches of mercury. The leaf moisture after the compression roll was around 53 percent. The adhesive mixture sprayed onto the surface to the Yankee dryer just before the compression roll consisted of 40 percent polyvinyl alcohol, 40 percent polyamide resin and 20 percent quaternized polyamide amine. The spray application rate was about 5.5 pounds of dry adhesive per pound of dry fiber. The creping bag angle was 78 degrees. A heated cover of natural gas partially around the Yankee had a supply air temperature of 680 degrees F to aid in drying. The moisture of the sheet after the creping blade was around 2.5 percent. The speed of the sheet machine 24 inches wide was 3,000 feet per minute. The crepe ratio was 1.30 or 30 percent. This tissue was folded together and calendered with two steel rollers at 20 pounds per linear inch. The product of two strata had the dryer / softener layer placed on the outside. The finished basis weight of the two-layer tissue at ambient humidity and temperature was 16.9 pounds per 2,880 square feet. The MD tension was 955 grams per 3 inches and the DC tension was 528 grams per 3 inches. The thickness of a tissue of two strata was 0.0088 inches. The stretch in the machine direction in the finished tissue was 18.7 percent. The optical surface crepe value was 1791.

It will be appreciated that the foregoing examples, given for purposes of illustration, are not to be construed as limiting the scope of this invention, which is defined by the following claims and all equivalents thereof.

Claims (12)

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

1. A method for creping a dried tissue fabric comprising: (A) spraying a creping adhesive onto the surface of a rotating creping cylinder, said creping adhesive comprising a mixture of aqueous polyamide resin and an amine polyamido quaternized; (b) adhering the tissue to the surface of the creping cylinder, said tissue comprising an imidazolinium quaternary compound having the following structural formula: wherein X = methyl sulfate or other compatible anion; and R = C 8 -C 22, aliphatic, normal, saturated or unsaturated; Y (c) dislodging the tissue from the creping cylinder by contacting the doctor blade positioned against the surface of the creping cylinder and presenting the fabric with a creping bag angle of 78 degrees or less, said crepe fabric tissue having a moisture content of about 2.5 percent by weight or less before contacting the doctor blade.

2. The method as claimed in clause 1 characterized in that the creping adhesive comprises from about 40 to about 50 percent by dry weight of polyamide.

3. The method as claimed in clause 1 characterized in that the creping adhesive comprises about 50 percent by dry weight of polyamide and about 50 percent by dry weight of quaternized amine polyamide.

4. The method as claimed in clause 1 characterized in that the creping adhesive comprises polyvinyl alcohol.

5. The method as claimed in clause 1 characterized in that the creping adhesive comprises about 40 percent by dry weight of polyamide, about 20 percent by dry weight of quaternized polyamide amine, and about 40 percent by weight Dry polyvinyl alcohol.

6. The method as claimed in clause 1 characterized in that the tissue fabric contains from about 0.05 to about 0.5 percent by dry weight of the imidazolinium quaternary compound.

7. The method as claimed in clause 1 characterized in that the tissue also comprises a silicone glycol having the following structural formula: wherein R = alkyl group Cj-Cg; Ri = acetate or hydroxyl group; x = 1 to 1,000; y = 1 to 50; m = 1 to 30; Y n = 1 to 30

8. The method as claimed in clause 1 characterized in that the creping bag angle is from about 70 degrees to 78 degrees.

9. The method as claimed in clause 1 characterized in that the tissue is layered and wherein the quaternary imidazolinium compound is in the layer that contacts the creping cylinder.

10. The method as claimed in clause 1 characterized in that the tissue is wet compressed.

11. The method as claimed in clause 1 characterized in that the tissue is dried continuously.

12. A tissue made by the method as claimed in clause 1. SUMMARY The invention consists of soft bulky tissue products resulting from the presence of a debonding / softening agent in the outer layers of the tissue and creped under "closed" bag conditions. The desuperiorizing / softening agents belong to a group of organic chemicals that include various quaternary imidazolinium compounds. These chemicals do not interfere adversely with the adhesion, unlike most of the debonders, to the drying surface of the tissue machine. These can therefore be placed in the outer layers of the tissue that make contact with the dryer surface and improve creping. The tissue can then be creped out of the drying surface using a closed bag, which is a bag angle of less than 80 degrees. Closed bag creping usually produces a less dense and thicker tissue but with a rough crepe. Closed bag creping and the presence of most of the debonders in the side-to-dryer layers would be expected to also produce rough crepe structures. However, the interaction of the debonding adhesive properties and the closed bag creping conditions produce a bulky tissue with a sufficiently fine crepe structure resulting in a high overall smoothness.