JP2834183B2 - Method for producing soft tissue paper treated with polysiloxane - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates generally to a method for making tissue paper, and more particularly to a soft, silky flannel-like feel and a high bulk with tactilely-sensitive bulk and physiological surface smoothness. The present invention relates to a method for producing bulk tissue paper.

BACKGROUND OF THE INVENTION Soft tissue paper is usually preferred as disposable paper towels, facial and toilet tissue. However, known methods and means for increasing the softness of tissue paper usually have an adverse effect on tensile strength. Therefore, in the design of tissue paper products, it is usually an issue to balance flexibility against tensile strength.

Both mechanical and chemical means have been introduced for the purpose of producing soft tissue papers, that is, tissue papers that are softly perceived by the user in their feel.
The flexibility that can be sensed by such touch is not particularly limited, but it is elastic, flexible (flexibilit).
y) and smoothness, as well as subjective items that feel like silk or flannel.
The present invention relates to the use of tissue additives, especially tissue papers, by the introduction of chemical additives, especially polysiloxane materials which impart a silky or flannel-like sensation to the tissue paper without making the user feel greasy or greasy. High bulk creped (cr
eped) to improve the tactilely perceptible flexibility of tissue paper. In addition, surfactants
May be added to further increase flexibility and / or planar smoothness and / or at least partially compensate for any reduction in wettability caused by the polysiloxane;
Moreover, binder materials such as starch may also reduce the strength and / or linting caused by the polysiloxane and, if used, surfactant additives.
It can be added to at least partially compensate for the increase in propensity.

A representative high bulk creped tissue paper that is completely soft according to current standards and amenable to the increased flexibility provided by the present invention is disclosed in the following U.S. Patents: Lawrence H. Sanford .Sanfo
rd) and James B. Sisson
No. 3,301,746 issued January 31, 1967; Peter G. Ayers, August 10, 1976
No. 3,974,025, issued dated; issued to George Morgan, Jr. and Thomas F. Rich on November 30, 1976
No. 3,994,771; Paul D. Trokha
n) 4,191,609 issued March 4, 1980; and 4,637,859 issued January 20, 1987 to Paul D. Trockhan. Each is characterized by a pattern of dense areas, i.e. a denser area than the rest of each of them,
Such dense areas result from densification during papermaking that results in crossed knuckles of the carrier fabric for imprinting. Other high bulk soft tissue papers include Jerry E.
U.S. Pat. No. 4,300,981 issued Nov. 17, 1981 to Jerry E. Carstens; and Edward R. Wells and Thomas A.
• disclosed in Thomas A. Hensler, 4,440,597, issued April 3, 1984; In addition, obtaining high bulk tissue paper by avoiding overall consolidation prior to final drying requires a D.L.
-Disclosed in US Patent No. 3,821,068 issued June 28, 1974 to DLShaw; overall use of a combination of debonder and elastic bonder in paper furnish. To avoid congestion, see JL Salvucci, Jr.
r) U.S. Pat. No. 3,812,0, issued May 21, 1974
No. 00 is disclosed.

Chemical debonders such as those envisaged in Salvussi and their theory of action are described by Friemark.
No. 3,755,220 issued Aug. 28, 1973; Meissel et al. Issued No. 3, Oct. 29, 1974.
No. 3,844,880; and Becker et al., January 1, 1979
It is disclosed in representative U.S. Patents, such as 4,158,594, issued on May 9, 2009. Other chemical treatments proposed to improve tissue paper include, for example, the method disclosed in Kenzi Hara et al., German Patent No. 3,420,940, i.e., dimethyl silicone oil which cleans and facilitates wiping. Such as silicone oil and vegetable,
There is a method of impregnating toilet tissue paper in combination with animal or synthetic hydrocarbon oils.

In addition, a well-known mechanical method of increasing the tensile strength of paper made from cellulose pulp is by mechanically refining the pulp prior to papermaking. In general, the higher the degree of purification, the higher the tensile strength. However, consistent with the above description of tissue tensile strength and flexibility, a high degree of mechanical refining of the cellulose pulp will adversely affect the flexibility of the tissue paper, except for the paper furnish and all other aspects of the process. There is no change in the aspect. However, by applying the present invention, the tensile strength can be increased without adversely affecting the flexibility; while the flexibility can also be improved without adversely affecting the tensile strength.

It is an object of the present invention to provide a method for producing a tissue paper having a high soft feel.

It is another object of the present invention to provide a method for producing a tissue paper having a silky flannel-like feeling.

Another object of the present invention is to provide a method for producing tissue paper having a high level of tactile flexibility at a specific level of tensile strength as compared to tissue paper softened by the prior art.

These and other objects are achieved using the present invention, as will be apparent from the disclosure below.

SUMMARY OF THE INVENTION The present invention relates to a method for producing soft tissue paper. The method wets the cellulosic fibers to form a web, and provides from about 10 to about 80 of the polysiloxane in an amount sufficient to retain about 0.004 to about 0.75% of the polysiloxane on a tissue paper basis on a dry fiber weight basis. % (Based on total web weight) fiber consistency
Sometimes involves applying to the web and then drying and creping the web. Preferably, the amount of polysiloxane retained on the tissue paper is from about 0.004 to about 0.3% based on the dry fiber weight of the tissue paper.
The resulting tissue paper has a basis weight and less fiber density of about 0.6 g / cc to about 10~65g / m ^2.

The polysiloxane is applied after formation of the wet web and before drying completely. Surprisingly, it has been found that a significant tissue softening effect can be achieved with significantly lower levels of polysiloxanes when the polysiloxane is applied to a wet web compared to a dry web (eg, during a conversion operation). did. In fact, an important feature of the method disclosed herein is that the silicone levels are low enough and economical. Moreover, tissue paper treated with low levels of polysiloxane retains a high level of wettability, an important feature of tissue products.

Preferred polysiloxanes for use with the method of the present invention include amino-functional polydimethylpolysiloxanes, wherein up to about 10 mole percent of the polymer side chains contain amino functional groups. Since it is difficult to confirm the molecular weight of the polysiloxane, the viscosity of the polysiloxane is used in the present invention as an index of the molecular weight that can be confirmed objectively.
Thus, for example, while about 2% substitution has been found to be very effective for polysiloxanes having a viscosity of about 125 centistokes, viscosities of about 5 million centistrokes or more can be substituted. It is effective with or without. In addition to such substitution by an amino function, effective substitutions can also be made at carboxyl, hydroxyl, ether, polyether, aldehyde, ketone, amide, ester and thiol groups. Among these available substituents, one group that includes amino, carboxyl, and hydroxyl groups is even more preferred than others, and the amino function is most preferred.

Examples of commercially available polysiloxanes are Dow 8075 and Dow 200 from Dow Corning; and Silwet 720 and Ucarsil EPS from Union Carbide.

The process for producing tissue paper treated with a polysiloxane according to the present invention may be performed to at least partially compensate for any decrease in wettability of the tissue paper that would otherwise result from the introduction of the polysiloxane and / or The method may further include the step of adding an effective amount of a surfactant to enhance the surface smoothness that can be perceived by touch. The effective amount of surfactant is preferably about 0,5 to the dry fiber weight of the tissue paper.
An amount such that 01 to about 2%, more preferably about 0.05 to about 1.0%, is retained by the tissue paper. Moreover, the preferred surfactants are non-cationic, and the tissue paper is manufactured such that post-production changes in the properties of the tissue paper that would otherwise occur due to the introduction of the surfactant can be substantially avoided. It is virtually immobile on the spot after being done. This has a melting point above that normally encountered during storage, transportation, commercialization, for example, about 50
This is achieved by the use of surfactants having a melting point above ℃ and the application of the tissue paper product example of the invention.

Moreover, the method for producing tissue paper according to the present invention is to at least partially compensate for any decrease in tensile strength or increase in lynching properties that would otherwise be caused by the introduction of the polysiloxane and the surfactant, if present. The method may further include the step of adding an effective amount of a binder material such as starch to the mixture. Preferably, the effective amount of binder material is such that about 0.01 to about 2%, based on the dry fiber weight of the tissue paper, is retained in the tissue paper.

All percentages, ratios and proportions herein are by weight unless otherwise indicated.

 The invention is described in further detail below.

DETAILED DESCRIPTION OF THE INVENTION Briefly stated, the present invention provides a tissue paper having a silky flannel-like feel and a high softness that can be perceived by the addition of a polysiloxane additive to a wet tissue web. Such methods may further include the addition of an effective amount of a surfactant material and / or a binder material such as starch to the wet web. Generally speaking, surfactants may be included to enhance tactilely perceptible physiological surface smoothness and / or to provide sufficient wetting for the intended purpose of the tissue paper (eg, toilet tissue). Yes; furthermore, binder materials such as starch are also present, at least in part, in any loss of tissue paper tensile strength and / or degradation of lynching that would otherwise be caused by the addition of polysiloxanes and surfactants if used. Can be included to make up for it. Surprisingly, very low levels of polysiloxanes when applied to wet tissue webs according to the present invention, as compared to the application of polysiloxanes to dry tissue webs (e.g., during conversion operations), result in a significant amount of It has been found that a tissue softening effect can be exhibited. To ensure a high retention rate,
A wet web is formed and dewatered prior to the application of the polysiloxane additive in reducing polysiloxane loss due to free water exclusion. Importantly, the level of polysiloxane used to soften the tissue paper was found to be low enough that the tissue paper could retain high wettability.

The present invention is applicable to, but not limited to, general tissue paper, conventional felt compacted tissue paper; patterned densified tissue paper as exemplified by Sanford-Sisson and his disciples; There are high bulk de-consolidated tissue papers as exemplified by Salvussy. The tissue paper may be of homogeneous or multi-layer construction, and the tissue paper product constructed therefrom may also be of single-layer or multi-layer construction. Tissue paper is about 10 to about 65 g /
It preferably has a basis weight of m ² and a density of about 0.60 g / cc or less. Preferably, basis weight of about 35 g / m ² or less, a density of about 0.
It is less than 30g / cc. Most preferably, the density is from about 0.04 to about
It is 0.20 g / cc.

Conventional pressed tissue papers and methods for making such papers are well known in the art. Such papers are typically made by depositing paper furnish on foraminous forming wires. This forming wire is commonly used in the industry by Fourdrinier
r) Called wire. If the furnish is deposited on the forming wire, it is called a web. The web is dewatered by compressing it and dried at an elevated temperature. The specific techniques and typical equipment for producing a web in the manner described above are well known to those skilled in the art. In a typical process, a low consistency pulp furnish is fed to a pressurized headbox. The headbox has an opening for supplying a dilute deposit of pulp furnish onto the fourdrinier wire to form a wet web. The web is then dewatered in a vacuum and dried in a compression operation in which the web is spread and pressed, for example, on a counter-mechanical part of a cylindrical roll, to provide about 7 to about 25% (by total web weight) fibers. It is typically dehydrated to consistency. The dewatered web is then used by Yankee
ee) Streams known in the art as dryers (stre
am) Pressurized and dried by a drum device. Pressure can be applied with a Yankee dryer by mechanical means such as a counter cylindrical drum that compresses against the web. A number of Yankee dryer drums are available, whereby additional pressurization may optionally occur between the drums. The tissue paper structure formed is referred to below as a conventional pressed tissue paper structure. Such sheets are considered to be densified because the web is subjected to substantial mechanical compression, during which the fibers are wet and then dried in compression. .

Pattern densified tissue papers are characterized by having a relatively high bulk portion of relatively low fiber density and an arrangement of dense zones of relatively high fiber density.
The high bulk portion is characterized as a pillow region. The dense zone is on the one hand called the knuckle area. The dense zones are either separated within the high bulk portion or are connected either completely or partially within the high bulk portion. A preferred method for producing a patterned densified tissue web is described in US Pat. No. 3,301,746 issued Jan. 31, 1967 to Sanford and Sisson; Aug. 1976 issued to Peter G. Ayers.
U.S. Pat. No. 3,974,025, issued on Mar. 10, and US Pat. No. 4,191,609 issued on Mar. 4, 1980, all of which are incorporated herein by reference. Incorporated in the specification.

Generally, a pattern densified web is formed by depositing a paper product on a perforated forming wire, such as a fourdrinier wire, to form a wet web, and then juxtaposing the web against an array of supports. It is preferably manufactured. The web is pressed against the array of supports, thereby obtaining a tight zone in the web at a location that spatially corresponds to the point of contact between the support array and the wet web. The remainder of the web that was not compressed during this operation is called the high bulk. The formation of the tight zone is effected by the application of hydraulic pressure, such as with a vacuum-type device or a blue-through dryer, or by mechanically pressing the web against a support array. The web is dewatered and optionally pre-dried in such a way that compression of the high bulk portion is substantially avoided. This is preferably done by hydraulic pressure, such as with a vacuum type device or blow dryer, where the high bulk portions are not compressed, or alternatively by mechanically pressing the web against the support array. The operations of dewatering, optional pre-drying and dense zone formation can be adjusted or partially adjusted to reduce the total number of processing steps performed. After formation of a dense zone, dewatering and optional pre-drying, the web is preferably completely dried so that mechanical processing can still be avoided. Preferably, from about 8 to about 55% of the tissue paper surface comprises a dense knuckle having a relative density of at least 120% of the high bulk portion.

The support arrangement is preferably a stamped carrier fabric having a knuckle-patterned substitution that functions as a support arrangement that promotes the formation of a dense zone when pressed. The knuckle pattern constitutes the support arrangement. Imprint carrier fabric is disclosed in U.S. Pat. No. 3,301,746 issued Jan. 31, 1967 to Sanford and Sisson; Salbusy J.
US Patent No. 3,821,068 issued May 21, 1974 to r.
No. 3,974,025, issued Aug. 10, 1976 to Ayers; Friedberg et al., 1971.
U.S. Pat. No. 3,573,164 issued Mar. 30, 1997; U.S. Pat. No. 3,473,576 issued to Amneus on Oct. 21, 1969; U.S. Patent issued Dec. 16, 1980 to Trokhan No. 4,239,065; and U.S. Pat. No. 4,528,239 issued to Trokhan on July 9, 1985.
The disclosures of each of the foregoing are incorporated herein by reference in their entirety.

Preferably, the paper furnish is first formed in a wet web on a perforated forming carrier, such as a Fourdrinier wire. The web is dewatered and transferred to a stamping fabric. on the other hand,
The paper product may be first deposited on a perforated support carrier that also functions as a marking fabric. Once formed, the wet web is dewatered and preferably thermally pre-dried to a selected fiber consistency at about 40 to about 80%. Dehydration is preferably performed in a suction box or other vacuum device or in a blow-through dryer. The knuckle imprint of the imprint fabric is imprinted on the web as described above before the web is completely dried. One way to do this is by mechanical pressure. This is done by pressing a nip roll that supports the printing fabric against the surface of a drying dryer, such as a Yankee dryer, where the web is placed between the nip roll and the drying drum. Further, preferably, the web is shaped against the printing fabric prior to complete drying by application of hydraulic pressure in a vacuum device such as a suction box or a blow dryer. Hydraulic pressure is applied during the initial dehydration, at another later process step, or a combination thereof, to imprint a denser zone.

The non-densified, non-pattern densified tissue paper structure includes Joseph Salbusy Jr and Peter N
U.S. Pat. No. 3,812,000 issued May 21, 1974 to Peter N. Yiannos; and Henry E.
-Described in U.S. Patent No. 4,208,459 issued June 17, 1980 to Henry E. Becker, Albert L. McConnell, and Richard Schutte. All of which are incorporated herein by reference. In general, the unconsolidated, unpatterned, densified tissue paper structure is used to deposit a paper product on an effective forming wire, such as a fourdrinier wire, to form a wet web, drain the web, and allow the web to drain. Produced by creping the web by removing further water without mechanical compression until it has a fiber consistency of at least 80%. Water is removed from the web by vacuum dewatering and thermal drying. The resulting structure is a soft but somewhat bulky sheet of relatively unconsolidated fibers. Preferably, the binding material is applied to each part of the web before grouping.

Papermaking fibers that can be used in the present invention include fibers typically obtained from wood pulp. Other cellulosic fibrous pulp fibers, such as cotton linters, bagasse, etc., can be used and are considered to be within the scope of the present invention. Synthetic fibers such as rayon, polyethylene and polypropylene fibers can also be used in combination with natural cellulose fibers. One example of a polyethylene fiber that can be used is Pulpex ^{™ from} Hercules, Inc. (Wilmington, Del.).

Available wood pulp includes kraft, chemical pulp such as sulfite and sulfate pulp, and mechanical pulp including, for example, groundwood and thermomechanical pulp and chemically modified thermomechanical pulp. However, chemical pulps are preferred because they can impart an excellent soft feel to the tissue sheets made therefrom. Pulp obtained from both deciduous trees (hereinafter, also referred to as "hardwood") and coniferous trees (hereinafter, also referred to as "softwood") can be used.

The paper products used to make the tissue paper structure in addition to the papermaking fibers may have other components or substances added to them, but they will be known in the art or later. Would. The type of additive desired depends on the specific end use of the tissue sheet envisioned. In products such as toilet paper, paper towels, facial tissue and other similar products, high wet strength is a desirable property. Thus, it is usually desirable to add a chemical known in the art as a "wet strength resin" to paper products.

A general article on the types of wet strength resins used in the paper industry can be found in TAPPI Monograph Series No. 29, Wet Strength in Paper and Paperboard, Technical Association of the Pulp and Paper Industry (New York, 1965). The most useful wet strength resins were typically cationic in character. Polyamide-epichlorohydrin resin is a cationic wet-strength resin for which specific applications have been found. Suitable types of such resins are described in U.S. Pat. No. 3,700,623 issued Oct. 24, 1972 and 3,772,076 issued Nov. 13, 1973, both issued to Keim. Which are all incorporated herein by reference. One useful polyamide-epichlorohydrin resin is sold by Hercules, Inc. of Wilmington, Del., Under the trade name Kymeme ^™ 557H.
Such resins are commercially available.

Polyacrylamide resins have also found use as wet strength resins. These resins are disclosed in U.S. Pat. No. 3,556,932, issued Jan. 19, 1971 to Coscia et al.
No. 3,556,933, issued Jan. 19, 1971 to Williams et al., Each of which is incorporated herein by reference. One market for polyacrylamide resins is American Cyanamid Co. of Stamford, CT, which sells one such resin under the trade name Parez ^™ 631NC.

Still other water soluble cationic resins useful in the present invention are urea formaldehyde and melamine formaldehyde resins. More common functional groups in these polyfunctional resins are amino groups and nitrogen-containing groups such as methylol groups bonded to nitrogen. Polyethyleneimine type resins also have utility in the present invention. It will be appreciated that the addition of a compound such as the above-mentioned wet strength resin to the pulp composition is optional and unnecessary for the practice of the present invention.

Types of polysiloxane materials suitable for use in the present invention include polymers, oligomers, copolymers and other multimonomer siloxane materials. The term polysiloxane as used herein includes all such polymers, oligomers, copolymers and other multimonomer siloxane materials. Moreover, the polysiloxane may be linear or branched, or may have a cyclic structure.

Preferred polysiloxane materials include those having monomeric siloxane units of the following structure: In the above formula, R ₁ and R ₂ for each siloxane monomer unit
Is each independently any alkyl, aryl, alkenyl, alkaryl, aralkyl, cycloalkyl, halogenated hydrocarbon or other group. Any of such groups may be substituted or unsubstituted. The R ₁ and R ₂ groups of any particular monomer unit may be different from the corresponding functional groups of the next adjacent monomer unit. Moreover,
The group may be linear or branched, or may have a cyclic structure. The groups R ₁ and R ₂ may further and independently of each other be other silicone functional groups such as, but not limited to, siloxanes, polysiloxanes and polysilanes. The groups R ₁ and R ₂ can also have any of a variety of organic functionalities, including, for example, alcohol, carboxylic acid, and amine functionalities.

The degree of substitution and the type of substituents have been found to affect the soft, silky feel and the relative degree of hydrophilicity imparted to the tissue paper structure. In general, the softness provided by polysiloisan increases in the degree of silkiness as the hydrophilicity of the substituted polysiloxane decreases. Amino-functional polysiloxanes are particularly preferred in the present invention.

Preferred polysiloxanes include linear organopolysiloxane materials of the general formula: In the above formula, each R ₁ -R ₉ group is independently any C ₁ -C
Is a ₁₀ unsubstituted alkyl or aryl group, and R ₁₀ is any substituted C ₁ -C ₁₀ alkyl or aryl group. Preferably, each R ₁ -R ₉ group is independently any C ₁ -C ₄ unsubstituted alkyl group. If skilled in the art, for example, R ₉ or
It will be appreciated that there is no technical difference in whether R ₁₀ is a substituent or not. The molar ratio of b to (a + b) is preferably 0 to about 20%, more preferably 0 to about 10%, and most preferably about 1 to about 5%.

In one particularly preferred example, R ₁ -R ₉ is a methyl group and R ₁₀ is a substituted or unsubstituted alkyl, aryl or alkenyl group. Such materials are commonly described herein as polydimethylsiloxanes having the appropriate specific functionality in the specific case. Examples of polydimethylsiloxanes include, for example, polydimethylsiloxane, polydimethylsiloxane having alkyl hydrocarbon R ₁₀ groups and one or more amino, carboxyl, hydroxyl, ether, polyether, aldehyde, ketone,
Amides, esters, polydimethyl siloxanes with other R ₁₀ functionalities including alkyl and alkenyl analogs of thiol and / or such functional groups. For example, R
The amino-functional alkyl group as ₁₀ is an amino-functional or aminoalkyl-functional polydimethylsiloxane. The exemplary list of these polydimethylsiloxanes is not meant to exclude other components not specifically set forth thereby.

The viscosity of the polysiloxanes useful in the present invention can vary over a wide range in which the viscosity of the polysiloxanes can usually vary, so long as the polysiloxanes are flowable or can be made to flow upon application to tissue paper. Within. This is not particularly limited and can range from as low as about 25 centistokes to as high as about 20,000,000 centistokes or more. High viscosity polysiloxanes that are themselves resistant to flow can be obtained by methods such as emulsifying the polysiloxane with a surfactant or dissolving the polysiloxane with the aid of a solvent such as hexane, shown for illustrative purposes only. , Can be effectively deposited on tissue paper webbing. Specific methods of applying the polysiloxanes to the tissue paper web are described in further detail below.

However, while not intending to be bound by operational theory, it is believed that the tactile efficacy of a polysiloxane is directly related to its average molecular weight, and that the viscosity is directly related to molecular weight. Therefore, it is relatively difficult to directly measure the molecular weight of polysiloxanes compared to measuring viscosity, so that tissue papers have high tactile responsiveness, i.e., flexibility, silkiness and flannel-like. Viscosity is used here as the apparent operational parameter for applying.

References that disclose polysiloxanes include, for example, U.S. Pat.
U.S. Pat. No. 3,964,500 issued June 22, 1976 to Drakoff; Pade
r) U.S. Pat. No. 4,364,8 issued on Dec. 21, 1982
37; and U.S. Patent No. 849,433, issued September 28, 1960 to Woolston. In 1984, Petrarch Systems, Inc.
ch Systems, Inc.)
Pages 81-217 contain a large list and description of polysiloxanes in general.

The polysiloxane is applied after formation of the wet web and before drying completely. Wet end of paper machine (we
It has been found that the addition of polysiloxane to the t-end (i.e., the papermaking composition) is impractical due to low retention levels of polysiloxane. Thus, in a typical process, the web is formed prior to the application of the polysiloxane to reduce the loss of the polysiloxane due to free water elimination and then dewatered. The polysiloxane is preferably used in the production of conventional pressed tissue paper, preferably at a fiber consistency level of about 10 to about 80% (based on the weight of the wet web), more preferably about 15 to about 35%.
% To about 20% to about 35% in the manufacture of tissue paper by a paper machine where the newly formed web is transferred from a fine mesh fourdrinier to a relatively coarse imprint / carrier fabric. Applied to a wet web having a fiber consistency of The reason for this is that it is preferred that the fibers be migrated at a fiber consistency that is sufficiently low that the fibers are substantially mobile during the migration, and that the polysiloxanes are discharged after the wastewater has progressed in the paper machine and their mobility has been substantially lost. Is preferably applied. In addition, the addition of polysiloxane at high fiber consistency ensures greater retention in and on the paper, i.e., the polysiloxane is significantly lost by water being removed from the web to increase its fiber consistency. Disappears. Surprisingly, retention of greater than about 90% is expected at preferred fiber consistency without the use of chemical retention aids.

Preferably, the polysiloxane is applied to the wet web in an aqueous solution, emulsion or suspension. The polysiloxane can also be applied as a solution containing a suitable non-aqueous solvent, for example, hexane, in which the polysiloxane is soluble or in which the polysiloxane can be mixed. The polysiloxane may be supplied in its raw form or preferably emulsified with a suitable surfactant emulsifier. Emulsified polysiloxanes are preferred for ease of application, i.e., the raw polysiloxane aqueous solution must be agitated to prevent separation into water and the polysiloxane phase.

The polysiloxane should be applied uniformly to the wet tissue paper web so that substantially the entire sheet has the tactile effect of the polysiloxane. Applying the polysiloxane to the wet tissue paper web in a continuous and patterned distribution is both within the scope of the present invention and meets the above criteria.

Methods for uniformly applying the polysiloxane to the web include suley and gravure printing. Spraying has proven to be most preferred because it is economical and allows for easy control of the amount and distribution of polysiloxanes. Preferably, the aqueous mixture containing the emulsified polysiloxane is sprayed onto a wet tissue web as it passes through a paper machine, which may be, for example, without limitation, depending on the desired fiber consistency level. Sunfard-Sisson, either before the dryer or after the pre-dryer (see above)
There is a paper machine with an overall configuration disclosed by J. A less preferred method is to deposit the polysiloxane on a forming wire or fabric and then contact the tissue web. Apparatus suitable for spraying a polysiloxane-containing liquid onto a wet web includes VIB Systems, Inc. of Tucker, Georgia (VIB Systems).
Systems, Inc.) external mixing air milling nozzles, such as 2 mm nozzles. An apparatus suitable for printing a polysiloxane-containing liquid on a wet web is a rotogravure printer.

It is surprising that low levels of polysiloxanes applied to wet tissue paper webs can impart a softened, silky, flannel-like, non-greasy feel to tissue paper without the aid of additives such as oils or lotions. Significantly, it has been discovered that these effects can be obtained in many embodiments of the present invention with high wettability in the range desired for toilets. Preferably, tissue paper treated with a polysiloxane according to the present invention contains no more than about 0.75% polysiloxane. It is an unexpected effect of the present invention that tissue paper treated with about 0.75% or less of polysiloxane could have the substantial softness and silky effect imparted to it at such low levels of polysiloxane. Generally, about
Tissue papers having less than 0.3%, preferably less than about 0.2% posiloxane, can have a substantial increase in softness, silkiness and flannel-like properties, but to compensate for any adverse effects on wettability arising from the polysiloxane. It maintains sufficient wettability for use as toilet paper without requiring the addition of a surfactant.

The minimum level of polysiloxane that should be maintained in the tissue paper is the level that is at least effective in imparting a tactile difference in softness, silky or flannel-like properties to the paper. The minimum effective level will depend on the specific type of sheet, the method of application, the specific type of polysiloxane, and whether the polysiloxane is supplemented with starch, surfactants or other additives or treatments. fluctuate. There is no limitation on the polysiloxane retention range applicable to tissue paper, but preferably at least about 0.004%, more preferably at least about 0.01%.
%, Most preferably at least about 0.02% of the polysiloxane is retained by the tissue paper.

Preferably, a sufficient amount of the polysiloxane to impart a soft feel is applied to both sides of the tissue paper, ie, to the outer surface of the surface level fibers. If the polysiloxane is applied to one side of the tissue paper, a portion will usually at least partially penetrate inside the tissue paper. In a preferred example, sufficient polysiloxane to provide tactile responsiveness has penetrated the entire thickness of the tissue paper so that both surfaces can impart the effects of the polysiloxane to it. One method that has been found to be useful in promoting polysiloxane penetration on the opposite side when the polysiloxane is applied to one side of the wet tissue paper web is from the other side of the wet tissue paper at the point of application of the polysiloxane. This is to vacuum-dry tissue paper.

In addition to treating tissue paper with a polysiloxane as described above, it has also been found desirable to treat such tissue paper with a surfactant. This can be any surfactant that can be present as an emulsifier for the polysiloxane.

Tissue papers having greater than about 0.3% polysiloxane are preferably treated with a surfactant when contemplated for applications where high wettability is desired. Most preferably, a non-cationic surfactant is applied to the wet tissue paper web to obtain a more flexible effect on a constant tensile basis as described above. The amount of surfactant required to increase hydrophilicity to the desired level is
It depends on the type and level of polysiloxane and the type of surfactant. However, as a general guideline, about 0.01 to about 2%, preferably about 0.05 to about 1.0
If the surfactant is retained by tissue paper, it is considered sufficient for most applications, including tissue paper, to have sufficient wettability at polysiloxane levels of about 0.75% or less. Can be

Preferred surfactants for the present invention are non-cationic, more preferably non-ionic. However,
Cationic surfactants can also be used. Non-cationic surfactants include anionic, nonionic, amphoteric and zwitterionic surfactants. Preferably, as described above, the surfactant was manufactured such that the tissue paper could substantially avoid post-production changes in the properties of the tissue paper that would otherwise result from the introduction of the surfactant. After being virtually immobile on the spot. This is achieved, for example, by the use of surfactants having a melting point above the temperature normally encountered during storage, transport and commercialization, for example a melting point above about 50 ° C. and the application of the tissue paper product examples of the invention. Further, it is preferred that the surfactant be water-soluble when applied to the wet web.

The level of non-cationic surfactant applied to the wet tissue paper web to exert the softness / tensile effect may be from the minimum effective level required to impart such effect on a constant tensile basis for the final product. Up to about 2%: preferably from about 0.01 to about 1%, more preferably from about 0.05 to about 1.0%, most preferably from about 0.05 to about 0.3% as a non-cationic surfactant retained on the web.

The surfactant preferably has an alkyl chain having 8 or more carbon atoms. Examples of anionic surfactants include:
There are linear alkyl sulfonates and alkyl benzene sulfonates. Examples of nonionic surfactants include alkyl glycoside esters such as Crodasta ^™ SL-40 from Croda, Inc. [New York, NY]; WK Langdong.
on) et al., US Patent No. 4,01, issued March 8, 1977.
Alkylglycoside ethers as described in US Pat. No. 1,389; and Glyco Chem.
alkylglycosides, including alkyl polyethoxylated esters, such as Pegosperse ^™ 200 ML (Greenwich, Conn.).
Alkyl polyglycosides are particularly preferred for use in the present invention. The above list of exemplified surfactants is merely illustrative of the type and is not meant to limit the scope of the invention.

Surfactants can be applied in the same manner and equipment used to apply the polysiloxanes, in addition to any emulsifying surfactants that may be present on the polysiloxane. These methods include spray and gravure printing. Preferably, the surfactant-containing aqueous mixture is sprayed onto a wet tissue web as it passes through a paper machine. Another method is to apply it to a forming wire or fabric before contacting the web. Any surfactant other than the polysiloxane emulsifying surfactant is hereinafter referred to as "surfactant", and any surfactant present as an emulsifying component of the emulsified polysiloxane is hereinafter referred to as "emulsifier".

The surfactant is applied to the tissue paper simultaneously with, after or before the polysiloxane. In a typical process, the surfactant is applied after formation of the wet web and before final drying. The surfactant is preferably from about 10 to about 80
%, More preferably from about 15 to about 35%, at a fiber consistency level of the wet tissue web. Surprisingly, the retention of non-cationic surfactant applied to the wet web is high even when it is applied under conditions where the surfactant is not ionically substantial on the battlefield. Retention of greater than about 90% is expected at preferred fiber consistency without the use of chemical retention aids.

As noted above, it is also desirable to treat the polysiloxane-containing tissue paper with a relatively low level of binder for lint control and / or to increase tensile strength. The term "binder" as used herein relates to various wet and dry strength additives known in the art. The binder is applied to the tissue paper simultaneously with, after, or before the polysiloxane and the surfactant, if used. The binder is preferably from about 10 to about 80%, more preferably from about 15 to
Added to wet tissue webs at a fiber consistency level of about 35%.

Starch has been found to be a preferred binder for use in the present invention. Preferably, the tissue paper is treated with an aqueous starch solution, and as described above, the sheet is wet when applied. In addition to reducing the linching of the final tissue paper product, even low levels of starch provide a reasonable amount of tissue paper tensile strength without imparting the boardiness (ie, stiffness) that would result from high levels of starch addition. Give improvement. Furthermore, according to this, improved strength compared to conventionally strengthened tissue papers, such as sheets having higher tensile strength due to increased pipe refining or the addition of other dry strength additives, for example. / A tissue paper having a flexibility relationship is obtained. This achievement is particularly surprising. This is because starch has traditionally been used in applications where flexibility is not a critical property, for example, in paperboard, for strength at the expense of flexibility. Moreover, starch has been used as a filler for printing and writing papers to improve surface printability.

Generally, starches suitable for the practice of the present invention are characterized by water solubility and hydrophilicity. Examples of starch materials include corn starch and potato starch, although this is not intended to limit the range of suitable starch materials, and waxy corn starch, which is technically known as amioca starch, is particularly preferred. Amioca starch differs from ordinary corn starch in that it is all amylopectin, since ordinary corn starch contains both amylopectin and amylose. The various unique features of Amioka starch are described in "Amika-starch from waxy corn", HH Choppeyer, Food Industries, December 1945, pp. 106-108 (p. 14).
76-1478).

The starch may be in granular or dispersed form, however, granular form is preferred. Preferably, the starch is cooked sufficiently to induce swelling of the granules. More preferably, the starch granules are expanded, such as by cooking just prior to dispersion of the starch granules. Such highly expanded starch granules are referred to as "fully cooked".
Dispersion conditions usually vary according to the size of the starch granules, the crystallinity of the granules and the amount of amylose present. A fully cooked amioca starch can be prepared, for example, by adding a starch granule aqueous slurry having a consistency of about 4% to about 190 ° F (about 88 ° C).
For about 30 to 40 minutes.

Examples of other starch materials that can be used include the National Starch and Chemical Company (New Jersey) modified to have a nitrogen-containing group, such as an amino group and a methylol group attached to the nitrogen. Modified cationic starches, such as those manufactured by Bridgewater, Inc.). Such modified starch materials have hitherto mainly been used as pulp composition additives to increase wet and / or dry strength. However, when applied in accordance with the present invention by application to wet tissue paper webs, they will have less effect on wet strength as compared to the wet end addition of similar modified starch materials. The latter was usually preferred, given that such modified starch materials are more expensive than unmodified starch.

The starch must be applied to the tissue paper while the paper is wet. The starch matrix material is preferably added to the wet tissue paper web when the web has a fiber consistency of about 80% or less. The non-cationic starch material is retained on the web sufficiently to provide an observable effect on flexibility at a particular strength level, even at higher degrees of purification, but is preferably about
Applied to wet tissue webs having a fiber consistency of 10 to about 80%, more preferably 15 to about 35%.

Preferably, the starch is applied to the tissue paper web as an aqueous solution. The method of application may be the same as described above for the application of the polysiloxane, preferably by spraying, or less preferably by printing. The starch is applied to the tissue paper web either before or after the addition of the polysiloxane and / or surfactant.

An amount of binder effective to increase lint control and associated strength when dried compared to the same sheet except that it is at least unbindered,
Preferably, starch is applied to the sheet. Preferably, from about 0.01 to about 2.0% of the binder is retained on the dry sheet, calculated on a dry fiber weight basis, more preferably, from about 0.1 to about 1.0% of the binder material,
Preferably, the starch substrate is retained.

Analysis of the amount of treatment chemical retained on the tissue paper web can be performed by any method accepted by the application industry. For example, the level of polysiloxane retained by tissue paper is measured by solvent extraction of the polysiloxane with an organic solvent, followed by atomic absorption spectroscopy to determine the level of silicon in the extract; nonionic surfactants such as alkyl glycosides The level of the agent is determined by extraction with an organic solvent followed by gas chromatography, which compares the level of surfactant in the extract; the level of anionic surfactants, such as linear alkyl sulfonates, is determined by aqueous extraction. The starch level is then determined by colorimetric analysis of the extract; the amylase digestion of starch to glucose,
It is then measured by colorimetry which checks the glucose level. These methods are exemplary and are not meant to exclude other methods useful for measuring the level of a particular component retained by the tissue paper.

The hydrophilicity of a tissue paper refers to the tendency of a tissue paper to be usually wetted with water. The hydrophilicity of the tissue paper will be determined somewhat by measuring the time required for the dry tissue paper to completely wet with water. This time is called the "wetting time". To provide a test method that is consistent and repeatable with respect to wet time, the following procedure is used for wet time measurement; first, about 4-3 / 8 x 4-3 / 4 inches (about 11.1) ×
A sample unit sheet of tissue paper structure (12 cm) dry (with fiber consistency level of 90% or more) is provided; second, the sheet is folded in parallel and then back to about 0.75 inch (about 1.9 cm) in diameter. 1 inch (about 2.5cm)
Third, the ball-shaped sheet is placed on a surface of distilled water at 72 ° F. (about 22 ° C.) and a timer is simultaneously set; When wetting is complete, the timer is stopped and read. Completion of the wetting is visually observed.

The preferred hydrophilicity of the tissue paper depends on its intended end use. In the case of tissue paper used in various fields of application, for example, toilet paper, it is desirable to completely wet in a relatively short time in order to prevent clogging when draining in a toilet. Preferably, the wetting time is no more than 2 minutes. More preferably, the wetting time is 30 seconds or less. Most preferably, the wetting time is less than 10 seconds.

The hydrophilic properties of the tissue examples of the present invention can, of course, be measured immediately after production. However, a substantial increase in hydrophilicity occurs in the first two weeks after the tissue paper has been manufactured, ie, two weeks after the paper has been manufactured. Therefore, it is preferable that the wet time is measured at the end of the second week.
Therefore, the wetting time measured after 2 hours at room temperature is referred to as "two week wetting time".

Tissue paper density, as that term is used herein, is the average density calculated as the basis weight of the paper divided by calipers, at which the appropriate unit conversion is made. As used herein, tissue caliper is 95 g / in ²
(15.5 g / cm ² ) is the thickness of the paper when subjected to a compressive load.

Example 1 The purpose of this example is to describe one method that can be used to produce a polysiloxane treated soft tissue paper sheet according to the present invention.

A pilot scale fourdrinier is used in the practice of the present invention. The paper machine has a laminated headbox having a top chamber, a center chamber and a bottom chamber. Where applicable, as shown in the examples below, the following operations also apply in such later examples. Briefly, a first fiber slurry, mainly from short papermaking fibers, is pumped from the top and bottom headbox chambers, while a second fiber slurry, mainly from long papermaking fibers, is pumped from the central headbox chamber. The fourdrinier wire is then fed to the top to form a three layer initial web there. The first slurry has a fiber consistency of about 0.11%, the fiber content of which is Eycalyptus Hardwood Kraft. The second slurry has a fiber consistency of about 0.15%, the fiber content of which is from Northern Softwood Kraft.
d Kraft). Dewatering occurs via Fourdrinier wire and is assisted by a deflector and vacuum box. Fourdrinier wire is 5 shed and the weave arrangement has 87 machine directions and 76 cross machine directions per inch each. The incipient wet web is transferred from the fourdrinier wire to a carrier fabric having a 5 shed weave of monofilaments at 35 machine directions and 33 cross machine directions per inch each at about 22% fiber consistency. . The following aqueous solution containing the emulsified polysiloxane composition is sprayed on the non-fabric side of the web from a 2 mm spray nozzle located on the opposite side of the vacuum dewatering box. Wet webs are about 22% when sprayed with an aqueous solution
% (Based on total web weight) fiber consistency. The sprayed web is carried on a carrier fabric through a vacuum dewatering box and then blow-through (bl
An ow through pre-dryer transfers the web onto a Yankee dryer. Other process and machine conditions are described below. The fiber consistency is about 27% after passing through the vacuum dewatering box and about 65% before being transferred onto the Yankee dryer by the action of the pre-dryer; creped adhesive of polyvinyl alcohol 0.25% aqueous solution is spray applied with an applicator The fiber consistency is increased to an estimated 99% before dry creping the web with a doctor blade. The doctor blade has a tilt angle of about 24 degrees and is placed at an impact angle of about 83 ° to the Yankee dryer; the Yankee dryer is about 800 fpm (feed / min) (about 244 m /
Minutes). The dried creped web is then
Pass between the calender rolls of the book. The two calender rolls are biased relative to each other by the roll weight, and the surface speed is 66
Operate at 0 fpm (about 201 m / min).

The aqueous solution sprayed onto the wet web from the spray nozzle contains 0.71% by weight of Dow Corning Q2-7224 (35% nonionic emulsion of amino-functional polydimethylpolysiloxane from Dow Corning). The volume flow rate of the aqueous solution from the nozzle is about 3 gallons / hr
・ It is ft (about 37 / hr · m) in the horizontal direction. The retention of polysiloxane applied to the web is typically about 90%.

The basis weight of the resulting tissue paper is 30g / m ^2, 0.
It has a density of 10 g / cc and contains 0.025% by weight of an amino-functional polydimethylpolysiloxane compound.

Importantly, the resulting tissue paper has a silky flannel-like feel and high tactile flexibility.

Example 2 The purpose of this example is to describe one method by which a tissue paper can be used to produce a soft tissue paper sheet that has been treated with a polysiloxane, a surfactant, and a starch.

A three-layer paper sheet is produced according to the method of Example 1 above. The tissue web, in addition to the treatment with the polysiloxane compound, also includes Clodesta SL-40 (an alkyl glycoside polyester nonionic surfactant from Croda) and fully cooked amioca produced as described herein. Processed with starch. The surfactant and starch are applied simultaneously with the emulsified polysiloxane composition as part of the aqueous solution sprayed from the paper machine spray nozzle. The concentration of Clodesta SL-40 nonionic surfactant in the aqueous solution is adjusted so that the level of surfactant retained is about 0.15% by dry fiber weight. Similarly, the starch concentration in the aqueous solution is such that the level of retained amioca starch is about
Adjusted to be 0.2%.

The resulting tissue paper has a basis weight of 30 g / m ^2,
0.10 g / cc density, 0.025 wt% Dow Q2-7224 polydimethylpolysiloxane, 0.15 wt% clostar SL
Contains -40 nonionic surfactant and 0.2% by weight cooked amioca starch. Importantly, the resulting tissue paper has a silky flannel-like feel and high tactile flexibility, yet has higher wettability and lower lint than tissue paper treated with only the polysiloxane composition. That is.

────────────────────────────────────────────────── (5) References JP-A-2-224626 (JP, A) US Patent 3,755,220 (US, A) US Patent 4,028,172 (US, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) D21H 27/40 D21H 3/62

Claims (19)

(57) [Claims] 1. A method for producing a soft tissue paper, comprising: a) wet depositing cellulosic fibers to form a web; b) 0.2% of the dry fiber weight of the tissue paper.
Applying a sufficient amount of a polysiloxane compound to the web at a fiber consistency of 10-80% based on total web weight, such that 004-0.75% polysiloxane is retained on the web; and c) the web Drying and creping; (the tissue paper has a basis weight of 10-65 g / m ² and 0.60
g / cc or less). 2. The method of claim 1, wherein 0.004 to 0.3% of the polysiloxane is retained on the web. 3. A polysiloxane comprising an amino, carboxyl,
Hydroxyl, ether, polyether, aldehyde,
The polydimethylpolysiloxane having a hydrogen bonding functional group selected from the group consisting of ketone, amide, ester, and thiol groups, wherein the hydrogen bonding functional group is present at a substitution molar ratio of 20% or less. The described method. 4. The method of claim 3, wherein the polysiloxane has a substitution mole fraction of 10% or less and a viscosity of 25 centistokes or more. 5. The method of claim 3 wherein the polysiloxane has a substitution mole ratio of 1.0 to 5% and a viscosity of 25 to 20,000,000 centistokes. 6. The method of claim 3 wherein the substitution mole is 2% and the viscosity is 125 centistokes. 7. The method according to claim 3, wherein the hydrogen bonding function is an amino function. 8. The method of claim 1, wherein the polysiloxane is applied to the web when the web has a fiber consistency of 15-35%. 9. A sufficient amount of a water-soluble surfactant, such that 0.01 to 2.0% of the surfactant, based on the dry fiber weight of the tissue paper, can be retained on the web by 10 to 80%, based on the total web weight. 2. The method of claim 1, further comprising applying to the web during fiber consistency. 10. The method according to claim 9, wherein the amount of the surfactant is 0.05 to 1.0% based on the dry fiber weight of the tissue paper. 11. The method according to claim 9, wherein the surfactant is non-cationic. 12. The method according to claim 11, wherein the non-cationic surfactant is a nonionic surfactant. 13. The method according to claim 9, wherein the surfactant has a melting point of at least 50 ° C. 14. A binder in an amount sufficient to retain 0.01 to 2.0% of the binder, based on the dry fiber weight of the tissue paper, on the web, based on the total web weight.
The method of claim 1, further comprising applying to the web at a fiber consistency of ~ 80%. 15. The method according to claim 14, wherein the binder is starch.
The method described in. 16. The method of claim 15, wherein 0.1 to 1.0% of the starch, based on the dry fiber weight of the tissue paper, is retained on the web. 17. The method of claim 15, wherein the starch is amioca starch. 18. A sufficient amount of binder, based on the total web weight, such that 0.01 to 2.0% of the binder, based on the dry fiber weight of the tissue paper, can be retained on the web.
10. The method of claim 9, further comprising applying to the web at a fiber consistency of ~ 80%. 19. The method according to claim 18, wherein the surfactant is non-cationic and the binder is starch.