CN1163645A - Paper products containing chemical softeners based on vegetable oils - Google Patents

Abstract

The present invention discloses fibrous cellulosic materials for use in the manufacture of soft, absorbent paper products such as paper towels, facial tissues, and toilet tissue. Paper products contain vegetable oil based quaternary ammonium chemical softening compounds. Examples of preferred vegetable oil-based quaternary ammonium chemical softening compounds include dioleoyl dimethyl ammonium chloride (i.e., di(octadec-z-9-enyl) dimethyl ammonium chloride (DODMAC) and dioleoyl dimethyl ammonium chloride (DODMAC). Erucoyl dimethyl ammonium chloride (i.e., di(docos-z-13-enyl) dimethyl ammonium chloride) (DEDMAC). According to the characteristics of paper products, the fatty acyl group of vegetable oil can be adjusted Saturation. Parameters that need to be adjusted to maximize the benefit of the unsaturated vegetable oil-based acyl groups used include the iodine value (IV) of the fatty acyl group and the weight of cis/trans isomers in the fatty acyl group.

Description

Paper products containing chemical softeners based on vegetable oils

This invention relates to tissue paper webs. More particularly, the present invention relates to soft, absorbent tissue webs useful for tissue paper products such as paper towels, napkins, facial tissues, and toilet paper.

Paper webs or sheets, sometimes called tissue paper or tissue paper webs or sheets, are used in a wide variety of ways in today's society. Such items as paper towels, napkins, face towels and toilet paper are major industrial products. It has long been recognized that three important physical properties of these products are: their softness; their absorbency, especially into aqueous systems; and their strength, especially wet strength. Much research and development work has been done with the aim of improving each of these properties without seriously affecting the other properties and improving two or three properties simultaneously.

Softness is the tactile sensation consumers feel when holding a particular product, rubbing it against their skin or rubbing it in their hands. This tactile sensation is a combination of several physical properties. One of the more important physical properties involved in softness is considered by those of ordinary skill in the art to be the stiffness of the paper web from which the product is made. Stiffness is generally considered to be directly dependent on the dry tensile strength of the web and the stiffness of the fibers from which the web is made.

Strength is the ability of the product and its constituent webs to maintain their physical integrity and resist tearing, brittleness and shredding under conditions of use, especially wet.

Absorbency is a measure of the ability of an article and its constituent webs to absorb quantities of liquids, especially aqueous solutions and dispersions. Total absorbency as perceived by the consumer is generally considered to be a combination of the total amount of liquid absorbed by a given amount of tissue paper at which it is saturated with liquid, and the rate at which the given amount of tissue paper absorbs liquid.

The use of wet strength resins to enhance the strength of paper webs is well known. For example, Westfelt described a variety of such substances and discussed their chemical properties in Cellulose Chemistry and Technology, Vol. 13, pp. 813-825 (1979). U.S. Patent No. 3,755,220 issued August 28, 1973 to Freimark et al. mentions that certain chemical additives known as debonding agents interfere with the natural fibers produced during sheet formation in the papermaking process - Bonding of fibers. The reduction in bonding results in a softer or less rough sheet. Freimark et al. go on to describe the use of wet strength resins to enhance the wet strength of the sheet while employing debonding agents to counteract the undesirable effect of the wet strength resins. These debonding agents do reduce the dry tensile strength, but generally also reduce the wet tensile strength.

US Patent No. 3,821,068 to Shaw, issued June 28, 1974, also describes that chemical debonding agents can be used to reduce stiffness and thereby increase the softness of tissue webs.

A number of chemical debonding agents have been disclosed in numerous references, such as in US Patent No. 3,554,862, issued January 12, 1971 to Hervey et al. These materials include quaternary ammonium salts such as trimethylcocoyl ammonium chloride, trimethyl oleoyl ammonium chloride, di(hydrogenated) tallow dimethyl ammonium chloride and trimethylstearyl ammonium chloride.

U.S. Patent No. 4,144,122 issued March 13, 1979 to Emanuelsson et al. describes the use of complex quaternary ammonium compounds such as bis(alkoxy(2-hydroxy)propylene)quaternary ammonium chloride to soften paper web. These authors also attempted to overcome the reduction in absorbency caused by debonding agents by using nonionic surfactants such as adducts of fatty alcohols with ethylene oxide and propylene oxide.

Illinois State, Armak Company of Chicago disclosed in its bulletin 76-17 (1977) that fatty acid esters using dimethyl di(hydrogenated) tallow ammonium chloride in combination with polyethylene glycol can impart softness to tissue paper webs and absorbency.

Typical results of research directed at an improved web are described in US Patent No. 3,301,746, issued January 31, 1967 to Sanford and Sisson. Despite the high quality webs produced by the process described in this patent, and despite the commercial success of products made from these webs, research continues to find improved products.

For example, US Patent No. 4,158,594, issued January 19, 1979 to Becker et al., describes a process they claim by which a strong, soft cellulosic sheet will be prepared. More specifically, they describe that the strength of tissue webs (which may have been softened by the addition of chemical debonding agents) can be enhanced by passing one surface of the web through a bonding material during processing (such as acrylic latex rubber emulsion, water-soluble resin or elastomeric bonding material) bonded to the creped surface of the finely patterned structure, the bonding material has been bonded to one surface of the paper web and the finely patterned The creped surface of the structure from which the paper web is creped to form a sheet material.

Conventional quaternary ammonium compounds, such as the well-known dialkyldimethylammonium salts (e.g., ditallow dimethyl ammonium chloride, ditallow dimethyl ammonium methyl sulfate, di(hydrogenated) tallow dimethyl ammonium chloride Ammonium chloride, etc.) are effective chemical softeners. Unfortunately, these quaternary ammonium compounds can have odor issues and are difficult to diffuse. The applicants have found that vegetable oil based quaternary ammonium salts are also effective as chemical softeners for enhancing the softness of fibrous cellulosic materials. Tissue paper prepared with vegetable oil-based quaternary ammonium softeners has good softness and absorbency and improved odor compared to animal oil-based quaternary ammonium softeners. In addition, due to the good fluidity (low melting point) of the vegetable oil-based quaternary ammonium salt softener, better dispersibility can be obtained with minimal or no diluent.

It is an object of the present invention to provide a soft, absorbent tissue product.

Another object of the present invention is to provide a soft, absorbent tissue tissue product.

Yet another object of the present invention is to provide a soft, absorbent tissue product.

Yet another object of the present invention is to provide a method of making soft, absorbent tissue (ie, facial and/or toilet tissue) and tissue products.

These and other objects are attained by the present invention and will become apparent from the following description.

The present invention provides soft, absorbent paper products. Briefly, this flexible paper product consists of:

(a) cellulosic papermaking fibers; and

(b) about 0.005% to 5.0% of the weight of said cellulose papermaking fiber has a quaternary ammonium salt softening compound of the following structural formula:

(R) _4-m -N ⁺ -[R ² ] _m X ^-

Among them, m is 1 to 3;

Each R is C ₁ -~C ₆ alkyl, hydroxyalkyl, hydrocarbyl, substituted hydrocarbyl, benzyl, or mixtures thereof;

Each R ² is a C ₁₁ -C ₂₃ hydrocarbyl or substituted hydrocarbyl substituent; and

X- is any anion compatible with the softener;

wherein the ^R2 moiety of the softening compound is derived from a _C12 - _C24 fatty acyl group having an iodine number greater than about 5 and less than about 100. Preferably, the majority of the fatty acyl groups are derived from vegetable oil sources.

Preferably, the quaternary ammonium compound is diluted with a liquid carrier to a concentration of about 0.01% to about 25% by weight before being incorporated into the fibrous cellulosic material. Preferably, the temperature range of the liquid carrier is 30°C to 60°C. Preferably, at least 20% of the quaternary ammonium compound added to the fibrous cellulose is retained.

Examples of preferred quaternary ammonium salts suitable for use in the present invention include compounds having the general formula:

(CH ₃ ) ₂ -N ⁺ -(C ₁₈ H ₃₅ ) ₂ X ^- and

(CH ₃ ) ₂ -N ⁺ -(C ₂₂ H ₄₃ ) ₂ X ^-

These compounds can be viewed as dioleoyl dimethyl ammonium chloride (i.e., bis(octadec-z-9-enyl) dimethyl ammonium chloride) (DODMAC) and dierucoyl dimethyl ammonium chloride, respectively. Ammonium chloride (ie, bis(docos-z-13-enyl)dimethylammonium chloride) (DEDMAC). It should be understood that since the oleoyl and erucyl fatty acyl groups are derived from naturally occurring vegetable oils (eg, olive oil, rapeseed oil, etc.), minor amounts of other fatty acyl groups can also be present. For a discussion of the composition of various naturally occurring vegetable oils, reference is made to Bailey's Industrial Oil and Fat Products, Third Edition, John Wiley and Sons (New York, 1964), incorporated herein by reference. According to the requirements of product characteristics, the saturation degree of vegetable oil fatty acyl group can be adjusted.

Briefly, the method of making the tissue paper web of the present invention comprises the steps of forming a papermaking furnish according to the aforementioned ingredients, depositing the papermaking furnish on a foraminous surface, such as a fourdrinier wire, and removing water from the deposited furnish.

All percentages, ratios and fractions herein are by weight unless otherwise specified.

Although the scope of protection of the subject matter of the present invention is specifically pointed out and clearly described in the claims at the end of the specification, it is believed that the present invention can be better understood by reading the following detailed description and the attached examples.

The terms "tissue web, paper web, paper sheet and paper product" as used herein refer to a paper sheet prepared by a process comprising the steps of forming an aqueous papermaking furnish, depositing the furnish on a porous surface Water is removed from the furnish (as on a fourdrinier paper machine), by gravity or vacuum assisted drainage (with or without pressure) and evaporation.

As used herein, "aqueous papermaking furnish" is an aqueous slurry of papermaking fibers and chemicals as described below.

The first step in the process of the present invention is to form an aqueous papermaking furnish. The furnish includes papermaking fibers (sometimes referred to hereinafter as wood pulp), and at least one vegetable oil-based quaternary ammonium compound, all of which are discussed below.

Various types of wood pulp are expected to generally comprise the papermaking fibers used in the present invention. However, other cellulosic fiber pulps such as linters, bagasse, rayon etc. may also be used, none of which are excluded from the claims of the present invention. Wood pulps useful herein include chemical pulps, such as kraft, sulfite, and kraft pulps, and mechanical pulps, such as groundwood, thermomechanical pulp, and chemically modified thermomechanical pulp (CTMP). Wood pulps derived from hardwoods and softwoods can also be used. Also useful in the present invention are fibers derived from recycled paper which may include any or all of the above pulps as well as other non-fibrous materials such as fillers and binders to facilitate virgin paper production. Preferably, the papermaking fibers used in the present invention comprise kraft pulp derived from northern softwood. (A) Quaternary ammonium compound

The present invention contains as an essential component about 0.005% to 5.0%, more preferably about 0.03% to 0.5% (based on dry fiber weight) of a quaternary ammonium compound having the following structural formula:

(a) cellulosic papermaking fibers; and

(b) about 0.005% to 5.0% by weight of said cellulose papermaking fibers of a quaternary ammonium salt softening compound having the following structural formula:

(R) _4-m -N ⁺ -[R ² ] _m X ^-where

m is 1 to 3;

Each R substituent is short chain C ₁ -C ₆ (preferably C ₁ -C ₃ ) alkyl, such as methyl (most preferred), ethyl, propyl, etc., hydroxyalkyl, hydrocarbyl, substituted hydrocarbyl , benzyl or mixtures thereof;

Each R ² is a long chain at least partially unsaturated (iodine value (IV) of about greater than 5 to about less than 100, preferably about 10 to 85), C ₁₁ to C ₂₃ hydrocarbyl or substituted hydrocarbyl substituent and trans Ion X ^- can be any softener-compatible anion, for example, acetate, chloride, bromide, methylsulfate, formate, sulfate, nitrate, and the like.

Preferably, the majority of ^R2 comprises fatty acyl groups comprising at least 90% of the _C18 - _C24 chain length. More specifically, the majority of ^R2 is selected from the group consisting of _C18 , _C22 and mixtures thereof containing at least 90%.

Quaternary ammonium compounds prepared entirely from saturated acyl groups are excellent softeners. However, it has now been found that compounds prepared with at least partially unsaturated acyl groups derived from vegetable oil sources (i.e., having an iodine value of about greater than 5 to about less than 85, more preferably about 10 to 85) have many benefits (such as better fluidity) ), and when certain conditions are met, are highly acceptable products to consumers.

Parameters that must be adjusted to obtain the benefits of using unsaturated acyl groups include: the iodine value (IV) of the fatty acyl group and the weight ratio of cis/trans isomers in the fatty acyl group. Any IV references below refer to the IV (iodine value) of the fatty acyl group, not the iodine value of the resulting quaternary ammonium compound.

Preferably, these quaternary ammonium salt compounds are made of fatty acyl groups with an IV of about 5-25, preferably about 10-25, more preferably about 15-20, and a cis/trans isomer weight ratio greater than about 30/70, Preferably greater than about 50/50, more preferably about 70/30; these compounds are stable when stored at low temperatures. These cis/trans isomer weight ratios provide optimum concentration properties within these IV ranges. At IVs in the range greater than about 25, the cis/trans isomer ratio is less critical unless higher concentrations are desired. The relationship between IV and concentration properties is described below.

Typically, hydrogenation of fatty acids to reduce polyunsaturation and IV to ensure better color results in a higher degree of trans configuration in the molecule. Thus, quaternary ammonium compounds derived from fatty acyl groups having lower IV values can be prepared by mixing fully hydrogenated fatty acids with contact hydrogenated fatty acids in a ratio that provides about 5 to 25 IV. The polyunsaturation content of the contact hardened fatty acids should be less than about 30%, preferably less than about 10%, more preferably less than about 5%. As used herein, these percentages of polyunsaturation refer to the number of polyunsaturated fatty acids (or fatty acyl groups) per 100 groups. During contact hardening, the weight ratio of cis/trans isomers can be controlled by methods known in the art, such as optimal mixing, use of specific catalysts and supply of sufficient _H2 , etc. Synthesis of Quaternary Ammonium Compounds

RCl＝衍生于油酸或芥子酸胺The synthesis of the preferred quaternary ammonium compounds used herein can be obtained by the following two-step process: Step A Amine Synthesis

RCl = derived from oleic acid or erucicamide

In a 22-liter three-necked flask equipped with an addition funnel, a thermometer, a mechanical stirrer, a condenser and an argon purging device, N-methyldiamine (440.9 grams, 3.69 moles) and triethylamine (561.2 grams, 5.54 mol) was dissolved in _CH2Cl2 ( _12L ). Vegetable oil based fatty acid chlorides (2.13 kg, 7.39 mol) were dissolved in 2 L _{of CH2Cl2} and slowly added to the amine solution. The amine solution was then heated to 35°C to keep the fatty acid chloride in solution as it was added. The acid chloride was added to raise the reaction temperature to reflux temperature (40°C). The addition of the acid chloride should be slow enough to maintain reflux, but not so fast that the dichloromethane escapes from the top of the condenser. The addition of the acid chloride was maintained for 1.5 hours. The solution was heated at reflux for an additional 3 hours. Heating was stopped and the reaction solution was stirred for 2 hours to cool to room temperature. _CHCl3 (12 L) was added. Wash the solution with 1 gallon of saturated NaCl and 1 gallon of saturated Ca(OH) ₂ . Let the organic layer stand overnight at room temperature. It _was then extracted three times (2 gallons each) with 50% _K2CO3 . It was then washed twice with saturated NaCl (2 gallons each). Any emulsion formed during these extractions can be dissolved by adding _CHCl3 and/or saturated salt and heating on a steam bath. The organic layer was then dried over MgSO ₄ , filtered and concentrated. Yield 2.266 kg oleoyl or erucoyl precursor amine, thin layer chromatography (TLC) on silica gel (one spot at Rf 0.69 in 75% ether/25% hexane).

Step B Quaternization

The oleoyl/erucoyl precursor amine (2.166 kg, 3.47 mol) and _CH3CN were heated on a steam bath until it became a liquid. This mixture was then poured into a 10 gallon glass-lined, stirred Pfaudler reactor containing _CH3CN (4 gallons). _CH3Cl (25 lbs, liquid) was added via test tube and the reaction was heated to 800C for 6 hours. The _CH3CN /amine solution was removed from the reactor, filtered, and the solids were dried at room temperature for about a week. The filtrate was rotovaped, allowed to air dry overnight and combined with the other solids. Yield: 2.125 kg of white powder.

Quaternary ammonium compounds can also be synthesized by other methods:

Put 0.6 mol of diethanolmethylamine into a 3-liter three-necked flask equipped with a reflux condenser, an argon (or nitrogen) inlet, and two addition funnels. In one addition funnel was placed 0.4 molar triethylamine and in a second addition funnel was placed a 1.2 molar 1:1 solution of erucoyl _chloride in _CH2Cl2 . _CH2Cl2 ( _750ml ) was added to the reaction flask containing the amine and heated to 35°C (water soluble). Triethylamine was added dropwise, and the temperature was raised to 40-45°C with stirring within 1.5 hours. Erucoyl chloride/dichloromethane solution was added dropwise, and the reaction solution was heated at 40-45° C. overnight (12-16 hours) under inert gas.

The reaction mixture was cooled to room temperature and diluted with chloroform (1500ml). The chloroform solution of the product was placed in a separatory funnel (4 L) and washed with saturated NaCl, dilute Ca(OH) ₂ , 50% _K2CO3 (three times) ^* and _finally with saturated NaCl. The organic layer was collected, dried over MgSO ₄ , filtered, and the solvent was removed by rotary evaporation. Final drying was performed under high vacuum (0.25 mmHg). ^* Note: The 50% _K2CO3 layer is below _the chloroform layer. Step Polymerization B Quaternization

The methyldiethanol erucate amine from step A was placed in the autoclave jacket along with 200-300 ml of acetonitrile (anhydrous). The sample was then inserted into the autoclave and vented three times with _N2 (16275 mmHg/21.4 atm) and once with _CH3Cl . The reaction was heated to 80° C. under CH ₃ Cl pressure of 3604 mmHg/4.7 atmospheres for 24 hours. The autoclave jacket was then removed from the reaction mixture. The samples were dissolved in chloroform, and the solvent was removed by rotary evaporation, then dried under high vacuum (0.25 mmHg).

Another method that can be used commercially to prepare the preferred quaternary ammonium compounds is to react fatty acids (eg, oleic acid, erucic acid) with methyldiethanolamine. Amine precursors can be formed using known reaction methods. As previously discussed, quaternary ammonium salts can be formed by reaction with methylene chloride.

The above-mentioned reaction method is a method well known in the art for preparing quaternary ammonium softening compounds. In order to achieve the IV, cis/trans ratios, and percent unsaturation set forth above, these methods usually must make other changes.

Several types of vegetable oils (eg, olive oil, rapeseed oil, safflower oil, sunflower oil, soybean oil, meadow foam, etc.) can be used as fatty acid sources to synthesize quaternary ammonium compounds. Preferably olive oil, Dowberry oil, safflower oil high in oleic acid, and/or rapeseed oil high in erucic acid are used to synthesize the quaternary ammonium compound. Most preferably, homoerucic acid derived from rapeseed oil is used to synthesize the quaternary ammonium compound. It should be understood that as the fatty acyl groups are derived from naturally occurring vegetable oils (eg, olive oil, rapeseed oil, etc.), minor amounts of other fatty acyl groups may also be present. For a discussion of the various constituents of naturally occurring vegetable oils, see Bailey's Industrial Oil and Fat Products, Third Edition, John Wiley and Sons (New York 1964), incorporated herein by reference.

Importantly, it has been found that the vegetable oil-based quaternary ammonium compounds of the present invention can be dispersed without the use of dispersing aids such as wetting agents. Without being bound by theory, it is believed that their excellent dispersibility is due to the good fluidity (low melting point) of vegetable oils. This is in contrast to conventional tallow based quaternary ammonium compounds which require a dispersing aid due to their relatively high melting point. Vegetable oils also provide improved oxidative and hydrolytic stability. Additionally, tissue paper prepared with vegetable oil-based softeners exhibited good softness and absorbency as well as improved odor performance compared to animal oil-based softeners.

The present invention is generally applicable to tissue papers including, but not limited to, conventional felt-pressed tissue papers; pattern-compacted tissue papers such as those exemplified by the aforementioned U.S. patents of Sanford-Sisson et al.; and high-bulk , Uncompacted tissue paper, as exemplified by US Patent issued May 21, 1974 to Salvucci, Jr. The tissue paper may be of homogeneous or multi-ply construction; the tissue paper thus produced may be of single-ply or multi-ply construction. Tissue structures formed from layered webs are described in US Patent 3,944,771, Morgan, Jr. et al., issued November 30, 1976, incorporated herein by reference. Typically, wet-laid composite, soft, bulky and absorbent paper structures are prepared from two or more layers of furnish preferably comprising different fiber types. The layers are preferably prepared by depositing onto one or more annular perforated screens separate streams of dilute fiber slurries, the fibers typically being relatively long softwood and relatively short hardwood fibers used in tissue papermaking. These layers are then combined to form a layered composite web. The web is then forced against the surface of an open mesh drying/imprinting fabric by application of a fluid, followed by thermal predrying on said fabric as part of the low density papermaking process. The layered web may be layered according to fiber type or the fiber content of each layer may be substantially the same. The tissue paper preferably has a basis weight of 10 g/m ² to about 65 g/m ² and a density of about 0.60 g/cm ³ or less. Preferably, the basis weight is 35 g/m ² or ^less ; the density is about 0.30 g/cm ³ or ^less . Most preferably, the density is between 0.04 g/ ^cm3 and about 0.20 g/ ^cm3 .

Conventional pressed tissue papers and methods of making such papers are well known in the art. Such papers are usually deposited from a papermaking furnish on a foraminous forming wire. The forming wire is known in the art as a Fourdrinier wire. Once the furnish is deposited on the forming wire, the furnish is called a web. The web is dewatered by pressing the web and drying at elevated temperature. Specific techniques and typical equipment for preparing paper webs according to the methods described above are well known in the art. In a typical process, a low consistency pulp furnish is provided by a pressurized headbox. The headbox has an opening for conveying a thin deposit of pulp furnish onto a fourdrinier wire to form a wet web. The web is then dewatered, usually by vacuum dewatering, to a fiber concentration of about 7% to 25% (based on the weight of the entire web) and further dried by a press operation in which the web is subjected to a vacuum produced by opposing mechanical components such as cylindrical rolls. pressure.

The dewatered web is then further pressed and dried using steam dryer equipment known in the art, such as a Yankee dryer. The web can be pressed by means of mechanical means such as cylindrical rolls against the web, which create pressure on the Yankee dryer. Vacuum can also be applied to the web as it is pressed against the Yankee surface. It is also possible to use multiple Yankee dryers, optionally with additional pressing between these dryers. The resulting tissue structure is hereinafter referred to as a conventional, pressed tissue structure. Such sheets are generally considered to be compacted because the web is subjected to considerable overall mechanical compression while the fibers are in a wet state, and then the web is dried (and optionally creped) while in the compressed state. ).

A densely patterned tissue paper is characterized by relatively high loft regions of relatively low fiber density and a series of compacted regions of relatively high fiber density. High loft regions, on the other hand, are characterized in that they are pillow regions. The dense areas are called knuckle regions. The dense regions can be discretely distributed in the high-loft regions or can be all or partly connected in the high-loft regions. A preferred method of making a densely patterned tissue paper web is disclosed in U.S. Patent No. 3,301,746, issued January 31, 1967 to Sanford and Sisson; U.S. Pat. Patent No. 3,974,025; US Patent No. 4,191,609 issued March 4, 1980 to Paul D. Trokhan; and US Patent 4,637,857 issued January 20, 1987 to Paul D. Trokhan; all of which are incorporated herein by reference.

Typically, densely patterned webs are preferably formed by depositing papermaking furnish on a foraminous forming wire, such as a Fourdrinier wire, to form a wet web, and then juxtaposing the web on a series of supports. The web is then pressed against a series of supports to form densified regions in the web at locations corresponding geographically to the points of contact between the propagation supports and the wet web. The remainder of the web that is not compressed during this operation is known as the high loft region. The high loft zone can be further dedensified by applying fluid pressure, eg with vacuum type devices or blow-through, or by mechanically pressing the web against a series of supports. The web is dewatered and optionally predried in such a way that compression of high expansion loose areas is substantially avoided. This is preferably accomplished by fluid pressure, such as with vacuum type devices or blown into dryer cylinders, or by mechanical compression of the web on a series of supports (wherein the high loft areas are not compressed). The dewatering operations, optional pre-drying and formation of the compaction zone may be combined or partially combined to reduce the total number of processing steps performed. After formation of the densified zone, dewatering and optional predrying, the paper web is dried completely, preferably still avoiding mechanical pressing. Preferably, about 8 to 55 percent of the tissue surface includes dense knuckle regions having a relative density of at least 125 percent of the density of the high loft regions.

The set of supports is preferably an embossed carrier fabric containing patterned displacement joints which act as a set of supports to facilitate the formation of the densified zone when pressure is applied. The pattern of joints constitutes the series of supports referred to earlier. Embossed carrier fabrics are disclosed in: U.S. Patent No. 3,301,746 issued January 31, 1967 to Sanford and Sisson; U.S. Patent No. 3,821,068 issued May 21, 1974 to Salvucci, Jr et al; U.S. Patent No. 3,974,025 issued to Ayers on August 10; U.S. Patent No. 3,573,164 issued to Friedbery et al. on March 30, 1971; U.S. Patent No. 3,473,576 issued to Amneus on October 21, 1969; December 16, 1980 US Patent No. 4,239,065, issued to Trokhan, and US Patent No. 4,528,239, issued July 9, 1985 to Trokhan, all of which are incorporated herein by reference.

Preferably, the furnish is first formed into a wet web on a foraminous forming support such as a Fourdrinier wire. The web is dewatered and conveyed to the press fabric. On the other hand, the furnish can also be initially deposited on a porous support carrier which also serves as an embossing fabric. Once the wet web is formed, it is dewatered and preferably thermally predried to a selected fiber consistency of between about 40-80%. Dewatering can also be done with suction boxes or other vacuum devices or blown into dryers. Before the web is completely dried, knuckle impressions of the embossing fabric are pressed into the web as previously discussed. One way to achieve this is through the application of mechanical pressure. This can be done, for example, by pressing a press roll supporting the imprinting fabric against the surface of a drying drum, such as a Yankee dryer. Also, it is preferred that the web is formed onto the impression fabric before the web is completely dry by applying vacuum means such as a suction box or fluid pressure blown into the dryer. The indentation of the densified regions can be induced by the application of fluid pressure during initial dehydration, in a separate, subsequent processing step, or in a combination of the two.

Uncompacted, unpatterned dense tissue structures are described in U.S. Patent Nos. 3,812,000, issued May 21, 1974, to Joseph L. Salvucci, Jr. and Peter N. Yiannos, and 6, 1980 US Patent No. 4,208,459 issued October 17 to Henry E. Becker, Albert L. McConnell and Richard Schutte, both of which are incorporated herein by reference. Generally, uncompacted, non-patterned dense tissue paper is prepared by depositing the papermaking furnish on a foraminous forming wire (such as a Fourdrinier wire) to form a wet paper web, draining the web and compressing it without mechanical compression. Excess water is removed until the web has a fiber consistency of at least 80%, and the web is creped. Water is removed from the web by vacuum dewatering and thermal drying. The resulting structure is a soft but relatively low strength sheet of high loft relatively uncompacted fibers. The bonding material is preferably applied to the web prior to creping.

Compacted, non-patterned dense tissue structures are conventional tissue structures well known in the art. Typically, compacted, non-patterned dense tissue paper structures are prepared by depositing papermaking furnish on a porous wire (such as a fourdrinier wire) to form a wet paper web, draining the web, Remove excess water with the help of the paper web until the paper web has a consistency of 25 to 50%, transfer the paper web to a hot dryer (such as a Yankee dryer), and crepe the paper web. In general, water is removed from the web by vacuum, mechanical pressing, and thermal means. The resulting structure is stronger and generally of uniform density, but less bulky, absorbent and soft.

The tissue webs of the present invention can be used in any application requiring a soft, absorbent tissue web. A particularly advantageous application of the tissue webs of the present invention is in the manufacture of paper towel, toilet tissue and facial tissue products. For example, two tissue webs of the present invention may be embossed and secured together in face-to-face relationship with an adhesive as described in U.S. Patent No. 3,414,459, issued December 3, 1968 to Wells (incorporated by reference) to form two layers of paper towels.

                          Analysis and Test Methods

Analysis of the amount of treatment chemical used in the present invention or left on the tissue web can be performed by any method available in the art. A. Quantitative Analysis of Quaternary Ammonium Compounds

For example, the amount of quaternary ammonium compound (such as dioleoyl dimethyl ammonium chloride (DODMAC), dierucoyl dimethyl ammonium chloride (DEDMAC)) left on the tissue paper can be determined by using the organic solvent DODMAC/ Solvent extraction method of DEOMAC, and then determined by anion/cation titration using Dimidium Bromide as indicator. These methods are intended to be exemplary and not exclusive of other methods that can be used to determine the amount of a particular component retained by tissue paper. B. Hydrophilic (Absorptive)

Hydrophilicity of tissue paper generally refers to the tendency of the tissue paper to be wetted by water. The hydrophilicity of tissue paper can be quantified to some extent by measuring the time required for a dry tissue paper to be completely wetted by water. This time is called "wetting time". In order to provide a consistent and repeatable test of the wetting time, the following method can be used to determine the wetting time: First, provide an adjusted sample unit paper sheet (the environmental condition for the paper test is 23+1°C and relative Temperature 50 + 2%, as specified by TAPPI (Association of Pulp and Paper Technology) Method T 402), approximately 4-3/8 inches x 4-3/4 inches (approximately 11.1 cm x 12 cm) tissue paper construction ; the second step is to fold the paper into 4 juxtaposed equal parts, and then roll it into a ball with a diameter of about 0.75 inches (about 1.9cm) to about 1 inch (about 2.5cm); the third step is to form a ball The paper sheet is placed on the surface of distilled water at a temperature of 23±1°C, and a timer is started at the same time; the fourth step is to stop the timer and read the time when the balled paper sheet is completely wetted. Complete wetting can be observed with the naked eye.

Of course, the hydrophilicity of embodiments of the tissue papers of the present invention can also be determined immediately after manufacture. However, the hydrophilicity of paper aged two weeks after manufacture increased significantly during the first two weeks after tissue paper preparation. Therefore, it is best to measure the wetting time at the end of the two weeks. Accordingly, the wetting time measured at the end of the two-week aging period at room temperature is referred to as the "two-week wetting time". c. Density

As used herein, the term "density of tissue paper" is the average density calculated by dividing the basis weight of the paper by its thickness, with appropriate unit conversions. As used herein, the caliper of tissue paper refers to the caliper of the paper under a compressive load of 95 grams per square ^inch (15.5 grams per square centimeter ⁾ . optional ingredients

Other chemicals commonly used in papermaking can be added to the chemical softening compositions described herein, or to the papermaking furnish, as long as they do not significantly and adversely affect the softening, absorbency and the present invention of the fibrous material. The softness enhancing effect of the quaternary ammonium softening compound. A. Wetting agent:

The present invention may contain, as an optional component, from about 0.005% to 3.0%, more preferably from about 0.03% to 1.0%, based on the weight of the as-formed fibers, of a wetting agent. (1) Polyol

Examples of water-soluble polyols useful as wetting agents in the present invention include glycerin, polyglycerol with a weight average molecular weight of about 150 to 800, and a weight average molecular weight of about 200 to 4000, preferably about 200 to 1000, most preferably About 200-600 polyethylene glycol and polypropylene glycol. Polyethylene glycol having a weight average molecular weight of about 200-600 is particularly preferred. Mixtures of the aforementioned polyols may also be used. A particularly preferred polyol is polyethylene glycol having a weight average molecular weight of about 400. This material is commercially available from Union Carbide Corporation of Danbury, Connecticut under the trade designation "PEG-400". (2) Nonionic surfactants (alkoxylated substances)

Suitable nonionic surfactants that may be used as wetting agents in the present invention include the addition products of fatty alcohols, fatty acids, fatty amines and the like with ethylene oxide and optionally propylene oxide.

Any of the specific types of alkoxylated materials described below can be used as nonionic surfactants. Suitable compounds are substantially water-soluble surfactants having the general formula:

R ² -Y-(C ₂ H ₄ O) _z -C ₂ H ₄ OH wherein, R ² of the solid and liquid compositions is selected from: primary, secondary and branched chain alkyl and/or acyl hydrocarbon groups; primary, secondary and branched alkenyl hydrocarbon groups; and primary, secondary and branched alkyl and alkenyl substituted phenolic hydrocarbon groups; said hydrocarbon groups having a hydrocarbon chain length of about 8 to 20, preferably about 10 to 18 carbon atoms. More preferably, the hydrocarbon chain length is about 16-18 carbon atoms for liquid compositions and about 10-14 carbon atoms for solid compositions. For the general formulas of ethoxylated nonionic surfactants herein, Y is typically -O-, -C(O)-O-, -C(O)N(R)- or -C( O) N(R) ^R2- , wherein ^R2 and R (if present) have the meanings given above, and/or R may be hydrogen, and z is at least about 8, preferably at least about 10-11. The performance and generally stability of the softener composition is reduced when fewer ethoxylated groups are present.

The nonionic surfactants herein are characterized by an HLB (Hydrophile-Lipophile Balance) of about 7-20, preferably about 8-15. Of course, by defining ^R2 and the number of ethoxylated groups, the HLB of a surfactant can generally be determined. It should be noted, however, that the nonionic ethoxylated surfactants used herein, for use in concentrated liquid compositions, contain relatively long chain ^R2 groups and are quite highly ethoxylated. Although shorter alkyl chain surfactants with short ethoxylated groups have desirable HLBs, they are not effective herein.

Examples of nonionic surfactants are listed below. The nonionic surfactants of the present invention are not limited to these examples. In these examples, the integer defines the number of ethoxy (EO) groups in the molecule. Linear alkoxylated alcohols a. Linear primary alcohol alkoxylates

The decyl, undecyl, dodeca, tetradecyl, pentadecyl alcohols having HLB values in the ranges described herein are useful wetting agents in the sense of the present invention. Examples of ethoxylated primary alcohols useful in the present invention as viscosity/dispersibility modifiers for the composition are n- _C18EO (10) and n- _C10EO (11). Ethoxylates of mixed natural or synthetic alcohols in the "oleic acid" chain length range are also useful in the present invention. Specific examples of such materials include oleyl-EO (11), oleyl-EO (18) and oleyl-EO (25). b. Linear secondary alcohol alkane hydrides

10, 11, 12, 14, 15, 18, and 18 of 3-hexadecanol, 2-octadecanol, 4-eicosanol, and 5-eicosanol with HLB values within the ranges described herein Nonadecethoxylates can be used as wetting agents in the present invention. Examples of ethoxylated secondary alcohols that can be used as wetting agents in the present invention are: 2-C ₁₆ EO (11), 2-C ₂₀ EO (11) and 2-C ₁₆ EO (14). Linear alkylphenoxylated alcohols

For alcohol alkoxylates, alkoxylated phenols, especially hexa-octadecyl ethoxylates of monohydric alkylphenols with an HLB within the range described in this invention, can be used as combinations according to the invention. Viscosity/dispersibility modifiers for materials. The hexa-octadecyl ethoxylates of p-tridecylphenol and m-pentadecylphenol and the like are useful in the present invention. Examples of ethoxylated alkylphenols useful as wetting agents in the mixtures according to the invention are: p-tridecylphenol EO (11) and p-pentadecylphenol EO (18).

The phenylene in the nonionic formula used in the present invention and known in the art is the equivalent of an alkylene group containing 2 to 4 carbon atoms. For the purposes of this invention, phenylene-containing nonionic surfactants are considered to contain an equivalent number of carbon atoms. The number of carbon atoms is: "calculated by adding the number of carbon atoms in the alkyl group to the sum of about 3.3 carbon atoms per phenylene group. Olefinic alkoxylates

Alkenols (both primary and secondary) and alkenylphenols corresponding to those previously disclosed can be ethoxylated to have their HLB within the range described herein for use as lubricants in the present invention. aerosol. branched chain alkoxylates

Branched primary and secondary alcohols derived from the well known "OXO" process can be ethoxylated and can be used as wetting agents in the present invention.

The above ethoxylated nonionic surfactants may be used alone or in combination in the compositions of the present invention. The term "nonionic surfactant" includes mixed nonionic surfactants.

The amount of surfactant used, if used, is preferably from about 0.01% to 2.0% by weight based on dry tissue fiber weight. The surfactant preferably has an alkyl chain of 8 or more carbon atoms. Examples of anionic surfactants are linear alkylsulfonates and alkylbenzenesulfonates. Typical nonionic surfactants are alkyl glycosides including alkyl glycosides, such as Crodesta SL-40 available from Croda Corporation (New York); U.S. Patent issued March 8, 1977 to W.K.Langdon et al. Alkyl glycoside ethers described in No. 4,011,389; and alkyl polyethoxylated esters such as Pegosperse 200ML available from Glyco Chemical Company (Greenwich, Connecticut) and from Rhone Poulenc Company (Cranbury, NJ) Bought IGEPALRC-520. B. Strength Additives

Other types of chemicals that can be added include strength additives to increase the dry tensile and wet burst strength of the tissue web. The present invention may contain, as an optional component, from about 0.01% to 3.0%, more preferably from about 0.3% to 15% by weight, based on dry fiber weight, of a water-soluble strength additive resin. (a) Dry Strength Additives

Examples of dry strength additives include carboxymethylcellulose and the Acco Chemicals series of cationic polymers (such as Acco 711 and Acco 514), with the Acco Chemicals series being preferred. These substances are commercially available from the American Cyanamide Company of Wayne, NJ. (b) Permanent wet strength additives

The permanent wet strength resins useful in the present invention can be of several types. In general, those resins which have been discovered and are hereafter employed in the art of papermaking can be used in the present invention. Several examples are shown in the aforementioned Westfelt text, incorporated herein by reference.

In general, wet strength resins are water-soluble, cationic materials. This means that the resin is water soluble when added to the papermaking furnish. It is highly likely, and even expected, that subsequent events such as crosslinking will render the resin insoluble in water. Also, some resins are soluble only under specific conditions (eg, within a limited pH range).

It is generally accepted that after wet strength resins have been deposited on, within, or between papermaking fibers, they typically undergo crosslinking or other curing reactions. As long as a large amount of water is present, crosslinking or curing reactions generally do not occur.

Various polyamide-epichlorohydrin resins are particularly useful. These substances are low molecular weight polymers with reactive functional groups such as amino, epoxy, and azetidinium groups. Methods for the preparation of such materials are fully described in the patent literature. US Patent No. 3,700,623, issued to Keim on October 24, 1972, and US Patent No. 3,772,076, issued to Keim on November 13, 1973, are examples of such patents, both of which are incorporated herein by reference.

Polyamide-epichlorohydrin resins sold under the trademarks Kymene 557H and Kymene 2064 by Hercules Incorporated of Wilmington, Delaware are particularly useful in the present invention. These resins are generally described in the aforementioned Keim patents.

Alkali-activated polyamide-epichlorohydrin resins useful in the present invention are sold under the Santo Res trademark, such as Santo Res 31 sold by Monsanto Company of St. Louis, MO. These types of materials are generally described in the following patents: U.S. Patent No. 3,855,158, Petrovich, issued December 17, 1974; U.S. Patent No. 3,899,388, August 12, 1975, Petrovich; US Patent No. 4,129,528 to Petrovich; US Patent 4,147,586 to Petrovich, issued April 3, 1979; and US Patent 4,222,921 to Van Eenam, issued September 16, 1980; all of which are incorporated herein by reference.

Other water-soluble cationic resins useful herein are polyacrylamide resins sold under the Parez trademark (eg, Parez 631NC) by the American Cyanamid Company of Stanford, Connecticut. These materials are generally described in the following US Patents: 3,556,932, Coscia et al., issued January 19, 1971, and 3,556,933, Williams et al., issued January 19, 1971, both of which are incorporated herein by reference.

Other types of water-soluble resins useful in the present invention include acrylic emulsions and anionic styrene-butadiene latexes. Many examples of these types of resins are described in US Patent 3,844,880, issued October 29, 1974 to Meisel, Jr. et al., incorporated herein by reference.

Other water-soluble cationic resins useful in the present invention are urea-formaldehyde resins and melamine-formaldehyde resins. These multifunctional, living polymers have a molecular weight of the order of several thousand. The more common functional groups include nitrogen-containing groups such as amino groups and nitrogen-attached hydroxymethyl groups.

Although less preferred, polyethyleneimine type resins can be used in the present invention.

A more comprehensive description of the aforementioned water-soluble resins, including their preparation, can be found in the TAPPI Monograph Series No. 29, Wet Strength of Paper and Board, of the Association for Pulp and Paper Technology (TAPPI) (New York, 1965) (Wet Strength In Paper and Paperboard), incorporated herein by reference. As used herein, the term "permanent wet strength resin" means a resin which, when placed in an aqueous medium, allows a sheet to retain a substantial portion of its original wet strength for a period of at least greater than two minutes. (C) Temporary wet strength additives

The above-mentioned wet strength additives generally result in paper products having permanent wet strength, ie, paper that retains a substantial portion of its initial wet strength over time when placed in an aqueous medium. However, in some types of paper products permanent wet strength can be a non-essential and unwanted property. Paper products, such as toilet paper, etc., are usually disposed of after entering the humic system after short-term use. If the paper product permanently retains its hydrolytic strength properties, clogging of these systems can result. More recently, producers have added temporary wet strength additives to paper products whose wet strength is sufficient for the intended application, but which decrease when soaked in water. The reduction in wet strength aids the flow of the paper product through the humic system.

Examples of suitable temporary wet strength resins include modified starch temporary wet strength agents sold by National Starch and Chemical Corporation (New York City, NY), such as National Starch 78-0080. Such wet strength agents can be prepared by reacting dimethoxyethyl-N-methyl-chloroacetamide with cationic starch polymers. Modified starch temporary wet strength agents are also described in US Patent No. 4,675,394, Solarek et al., issued June 23, 1987, incorporated herein by reference. Preferred temporary wet strength resins include those disclosed in US Patent No. 4,981,557, issued January 1, 1991 to Bjorkquist, incorporated herein by reference.

With regard to the types and specific examples of permanent and temporary wet strength resins listed above, it should be understood that these resins are exemplary only and are not intended to limit the scope of the invention.

Mixtures of compatible wet strength resins may also be used in the practice of this invention.

The optional chemical additives listed above are exemplary only and are not meant to limit the scope of the present invention.

The following examples are used to illustrate the practice of the present invention, but not to limit the present invention. Example 1

The purpose of this example is to illustrate aqueous dispersions that can be used to prepare vegetable oil-based quaternary ammonium compounds such as dioleoyldimethylammonium chloride (DODMAC) or dierucoyldimethylammonium chloride (DEDMAC) liquid method.

A 2% dispersion of DODMAC was prepared according to the following procedure: 1. Measure a known weight of DODMAC; 2. Heat DODMAC to about 50°C (122°F); 3. Pre-adjust the dilution water to pH=3 and about 50 °C (122°F); 4. Mix thoroughly to form an aqueous submicron particle dispersion of DODMAC softening composition. 5. The particle size of the vesicle dispersion was measured by optical microscopy. The particle size range is about 0.1 to 1.0 microns.

A 2% dispersion of DEDMAC was prepared according to the following procedure: 1. Measure a known weight of DEDMAC; 2. Heat DEDMAC to about 50°C (122°F); 3. Pre-adjust the dilution water to pH=3 and about 50 °C (122°F); 4. Mix well to form an aqueous submicron particle dispersion of the DEDMAC softening composition. 5. The particle size of the vesicle dispersion was measured by optical microscopy. The particle size range is about 0.1 to 1.0 microns. Example 2

The purpose of this example is to illustrate the use of blow-dry papermaking techniques to produce soft and absorbent paper towels treated with a chemical softener composition of vegetable oil based quaternary ammonium salt softeners (DODMAC) and permanent wet strength resins .

A small scale Fourdrinier paper machine was used in the practice of the present invention. First, a 1% chemical softener solution was prepared according to the method of Example 1. Next, a 3% (by weight) aqueous NSK (Northern Softwood Kraft) slurry was prepared in a conventional repulper. The NSK slurry was lightly refined, and a solution of 2% permanent wet strength resin (i.e., sold by Hercules, Wilmington, Delaware) was added to the NSK slurry pipeline at a ratio of 1% dry fiber weight. Kymene 557H). The adsorption of NSK to Kymene 557H was enhanced by an in-line mixer. A 1% solution of carboxymethylcellulose (CMC) was added after the in-line mixer at a rate of 0.2% dry fiber weight to enhance the dry strength of the fiber matrix. The adsorption of NSK to CMC can be enhanced by an in-line mixer. Then, a 1% solution of a chemical softener (DODMAC) was added to the NSK slurry at a rate of 0.1% by dry fiber weight. The adsorption of NSK to the chemical softener mixture can also be enhanced by an in-line mixer. Dilute NSK to 0.2% with a fan pump. In the third step, 3% (by weight) CTMP pulp (pre-impregnated preheated chip groundwood pulp) was prepared in a conventional repulper. The nonionic surfactant was added to the repulper at a rate of 0.2% by dry fiber weight. Before the slurry pump, add a solution of 1% chemical softener mixture to the CTMP slurry delivery pipeline at a ratio of 0.1% by weight of the dry dimension. Adsorption of the chemical softener mixture by CTMP can be enhanced by an in-line mixer. The CTMP slurry was diluted to 0.2% with a fan pump. The treated furnish mixture (NSK/CTMP) is mixed in the headbox and deposited on a Fourdrinier wire to form a web. Dewatering is carried out through fourdrinier wires with the help of baffles and vacuum boxes. Fourdrinier was a 5-shed, satin weave configuration with 84 filaments per inch in the machine direction and 76 filaments per inch in the cross-machine direction, respectively. A wet web with a fiber concentration of about 22% was conveyed from a Fourdrinier wire at the nipple onto a photopolymer fabric having 240 linear Idaho units per square inch, 34% knuckle area, and a depth of 14 mils. photopolymer. Further dewatering was accomplished with vacuum assisted draining to a fiber concentration of about 28%. The patterned web was predried by air blowing to a fiber concentration of about 65% by weight. The web was then adhered to the surface of the Yankee dryer with a spray-on creping adhesive containing a 0.25% aqueous solution of polyvinyl alcohol (PVA). The fiber concentration was increased to about 96% before the web was dry creped with a doctor blade. The doctor blade had a bevel angle of about 25° and was positioned relative to the Yankee dryer to provide an impingement angle of about 81°; the Yankee dryer was operating at about 800 ft/min (about 244 m/min). The dry web was formed into a roll at a speed of 700 feet per minute (214 meters per minute).

The two-ply web was made into a tissue product by embossing and lamination using a PVA binder. The tissue has a basis weight of about 26#/3M Sq Ft (square feet), contains about 0.2% chemical softener (DODMAC) and about 1.0% permanent wet strength resin. The resulting tissue is soft, absorbent and has great strength when wet. Example 3

The purpose of this example is to illustrate the preparation of soft and absorbent toilet paper treated with a chemical softener composition of a vegetable oil based quaternary ammonium salt softener (DEDMAC) and a temporary wet strength resin using blow-drying and layered papermaking techniques .

A small scale Fourdrinier paper machine was used in the practice of the present invention. First, a 1% solution of chemical softener was prepared according to the method of Example 1. In the second step, a 3% by weight aqueous slurry of NSK was prepared in a conventional repulper. The NSK slurry was lightly refined and added to the NSK infusion line at a rate of 0.75% dry fiber weight with a 2% solution of a temporary wet-strength resin (i.e., NSK sold by National Starch and Chemicals, New York City, NY). National Starth 78-0080). Adsorption of temporary wet strength resin on NSK fibers was enhanced by an in-line mixer. The NSK slurry was diluted to a concentration of about 0.2% at the fan pump. In the third step, a 3% (by weight) aqueous slurry of eucalyptus fibers was prepared in a conventional repulper. A 1% solution of chemical softener mixture was added to the eucalyptus stock line prior to the stock pump at a rate of 0.2% dry fiber weight. The adsorption of the eucalyptus fiber to the chemical softener mixture was enhanced by an in-line mixer. The eucalyptus slurry was diluted to a concentration of about 0.2% at the fan pump.

The treated furnish mixture (30% NSK/70% eucalyptus) was mixed in the head box and deposited on a Fourdrinier wire to form a web. Dewatering is carried out through fourdrinier wires with the help of baffles and vacuum boxes. The fourdrinier was a 5-shuttle, satin weave configuration with 84 filaments per inch in the machine direction and 76 filaments per inch in the cross-machine direction, respectively. At the nipple, a wet web with a fiber concentration of approximately 15% is transferred from a photopolymer wire onto a photopolymer fabric with 562 linear Idaho units per square inch, 40% knuckle area, and 9 mil deep photopolymer fabric. polymer. Further dewatering was accomplished by vacuum assisted drainage until the web had a fiber consistency of about 28%. The patterned web was further predried by air blowing to a fiber consistency of about 65% by weight. The web was then bonded to the Yankee dryer surface with a spray creping adhesive containing an aqueous solution of 0.25% polyvinyl alcohol (PVA). The fiber concentration was increased to 96% of the projected value before drying the creped web with a doctor blade. The doctor blade had a bevel angle of about 25° and was positioned relative to the Yankee dryer to provide an impingement angle of about 81°; the Yankee dryer was operating at a rate of about 800 feet per minute (about 244 meters per minute). The dry web was formed into a roll at a rate of 700 feet per minute (214 meters per minute).

Converts the paper web into a single ply tissue paper product. The tissue paper has a basis weight of about 18#/3M Sq Ft, contains about 0.1% vegetable oil based quaternary ammonium softener (DEOMAC) and about 0.2% temporary wet strength resin. Importantly, the resulting tissue paper is soft, absorbent and suitable for use as facial and/or toilet paper. Example 4

The purpose of this example is to illustrate the preparation of soft and absorbent toilet paper treated with a vegetable oil-based quaternary ammonium softener (DEDMAC) and dry strength additive resin using the blow-dry papermaking technique.

A small scale Fourdrinier paper machine was used in the practice of the present invention. First, a 1% chemical softener solution was prepared according to the method of Example 1. Next, a 3% by weight aqueous slurry of NSK was prepared in a conventional repulper. The NSK slurry was gently refined and 2% dry strength resin (i.e., Acco 514 and Acco 711, sold by American Cyanamid, Fairfield, Ohio) was added to the NSK stock line at a rate of 0.2% dry fiber weight. Adsorption of dry strength resin on NSK fibers was enhanced by an in-line mixer. At the fan pump, the NSK slurry was diluted to a concentration of about 0.2%. In the third step, a 3% by weight aqueous slurry of eucalyptus fibers was prepared in a conventional repulper. A 1% chemical softener solution was added to the eucalyptus stock line before the stock pump at a rate of 0.2% by dry fiber weight. The adsorption of eucalyptus fibers to chemical softeners can be enhanced by an in-line mixer. At the fan pump, the eucalyptus slurry was diluted to a concentration of about 0.2%.

The treated furnish mixture (30% NSK/70% Eucalyptus) was mixed in a head box and deposited on a Fourdrinier wire to form a web. Dewatering is carried out through fourdrinier wires with the help of baffles and vacuum boxes. The Fourdrinier was a 5-shuttle, satin weave configuration with 84 and 76 filaments in the machine and cross-machine directions, respectively. At the nipple, a wet web with a fiber concentration of approximately 15% is transferred from a photopolymer web onto a photopolymer fabric having 562 linear Idaho units per square inch, 40% knuckle area, and 9 mils deep of photopolymers. Further dewatering was achieved by vacuum assisted draining until the web had a fiber consistency of about 28%. The patterned web was predried to a fiber concentration of about 65% by weight by air blowing. The web was then bonded to the surface of the Yankee dryer with a spray-on creping adhesive containing 0.25% polyvinyl alcohol (PVA) in water. The fiber concentration was increased to 96% of the projected value before drying the creped web with a doctor blade. The doctor blade had a bevel angle of about 25° and was positioned relative to the Yankee dryer to provide an impingement angle of about 81°; the Yankee dryer was operating at a speed of about 800 feet per minute (about 244 meters per minute). The dry web was wound on a take-up roll at a speed of 700 ft/min (214 m/min).

The ply bonding technique is used to form two ply webs into a tissue product and laminate them together. The tissue has a basis weight of about 23#/3M Sq Ft, contains about 0.1% chemical softener (DEDMAC) and about 0.1% dry strength resin. Importantly, the resulting tissue paper is soft, absorbent and suitable for use as facial and/or toilet paper. Example 5

The purpose of this example is to illustrate the preparation of soft and absorbent toilet paper treated with a vegetable oil based quaternary ammonium softener (DEDMAC) and dry strength additive resin using conventional dry papermaking techniques.

A small scale fourdrinier paper machine is used in the practice of the present invention. First, a 1% chemical softener solution was prepared according to the method of Example 3. In the second step, a 3% by weight aqueous slurry of NSK was prepared in a conventional repulper. The NSK stock was lightly refined and a 2% dry strength resin solution (i.e., Acco 514, Acco 711 available from American Cyanamid Company, Wayne, NJ) was added to the NSK stock line at a rate of 0.2% by dry fiber weight. Sale). Adsorption of dry strength resin on NSK fibers was enhanced by an in-line mixer. At the fan pump, the NSK slurry was diluted to a concentration of about 0.2%. In the third step, an aqueous slurry of 3% (by weight) eucalyptus fibers was prepared in a conventional repulper. A 1% chemical softener solution was added to the eucalyptus stock line before the stock pump at a rate of 0.2% by dry fiber weight. The adsorption of the eucalyptus fiber to the chemical softener mixture can be enhanced by an in-line mixer. At the fan pump, the eucalyptus slurry was diluted to a concentration of about 0.2%.

The treated furnish mixture (30% NSK/70% Eucalyptus) was mixed in a head box and deposited on a Fourdrinier wire to form a web. Dewatering is carried out through fourdrinier wires with the aid of baffles and vacuum boxes. The Fourdrinier wire was a 5-shed, satin weave configuration with 84 filaments per inch in the machine direction and 76 filaments in the cross-machine direction, respectively. At the delivery, the wet web with a fiber concentration of about 15% is conveyed from the Fourdrinier wire onto a conventional felt. Further dewatering was performed by vacuum assisted draining until the web had a fiber consistency of about 35%. The web is then bonded to the surface of the Yankee dryer. The fiber concentration was raised to 96% of the projected value before the web was dry creped with a doctor blade. The doctor blade had a bevel angle of about 25° and was positioned relative to the Yankee dryer to provide an impingement angle of about 81°; the Yankee dryer was running at about 800 feet per minute (about 244 meters per minute). The dry web was wound on a take-up roll at a speed of 700 ft/min (214 m/min).

Two-ply paper webs are formed into tissue paper products and laminated together using ply bonding techniques. The tissue paper has a basis weight of about 23#/3M Sq Ft, contains about 0.1% chemical softener (DEDMAC) and about 0.1% dry strength resin. Importantly, the resulting tissue paper is soft, absorbent and suitable for use as facial and/or toilet paper.

Claims (24)

1. A soft paper product comprising: (a) cellulosic papermaking fibers; and (b) about 0.005-5.0% by weight of said cellulose papermaking fibers of a quaternary ammonium salt softening compound of the general formula: (R) _4-m -N ⁺ -[R ² ] _m X ^-where m is 1 to 3; Each R is C ₁ -C ₆ alkyl, hydroxyalkyl, hydrocarbyl, substituted hydrocarbyl, benzyl, or mixtures thereof; Each R ² is a C ₁₁ -C ₂₃ hydrocarbyl or substituted hydrocarbyl substituent; and X- is any anion compatible with the softener; wherein the ^R2 moiety of the softening compound is derived from a _C12 - _C24 fatty acyl group having an iodine value of about greater than 5 to less than about 100. 2. A paper product according to claim 1 wherein a majority of said fatty acyl groups are derived from a vegetable oil source. 3. The paper product according to claim 2, wherein said fatty acyl group has an iodine value of about 10-85. 4. The paper product according to claim 3, wherein the cis/trans isomer weight ratio of said fatty acyl groups is greater than about 50/50. 5. The paper product according to claim 3, wherein the majority of ^R2 comprises fatty acyl groups comprising at least 90% of the _C18 - _C24 chain length. 6. A paper product according to claim 5, wherein the majority of ^R2 comprises fatty acyl groups comprising at least 90% _C18 . 7. A paper product according to claim 5, wherein the majority of ^R2 comprises fatty acyl groups containing at least 90% _C22 . 8. The paper product according to claim 1, further comprising from about 0.005% to 3.0% of a humectant. 9. The paper product according to claim 8, wherein said wetting agent is a water-soluble polyol. 10. The paper product according to claim 8, wherein said wetting agent is a linear alkoxylated alcohol. 11. The paper product according to claim 8, wherein said wetting agent is a linear alkylphenoxylated alcohol. 12. The paper product according to claim 2, wherein each R is a _C1 to _C3 alkyl group. 13. The paper product according to claim 12, wherein each R is methyl. 14. The paper product according to claim 2, wherein m=2. 15. The paper product according to claim 3, wherein the polyunsaturation of the fatty acyl groups is less than about 30%. 16. The paper product according to claim 15, wherein the polyunsaturation of the fatty acyl groups is less than about 10%. 17. The paper product according to claim 12, wherein X is selected from the group consisting of chloride, acetate, methylsulfate, and mixtures thereof. 18. The paper product according to claim 6, wherein a majority of said vegetable oil-based fatty acyl groups are derived from olive oil. 19. The paper product according to claim 7, wherein a majority of said vegetable oil-based fatty acyl groups are derived from rapeseed oil. 20. The paper product according to claim 6, wherein a majority of said vegetable oil-based fatty acyl groups are derived from high oleic safflower oil. 21. The paper product according to claim 7, wherein a majority of said vegetable oil-based fatty acyl groups are derived from Peckia Dowthorne oil. 22. The paper product according to claim 1, wherein said paper product is a tissue. 23. The paper product according to claim 1, wherein said paper product is a facial tissue. 24. The paper product according to claim 1, wherein said paper product is toilet paper.