JPH03900A - Manufacture of soft tissue paper treated by polysiloxane - Google Patents

Abstract

PURPOSE: To economically produce the subject product having a soft silky and flannel-like feeling by applying a polysiloxane compound to a web formed by wet-laying cellulose fibers and kept in a wet state thereof. CONSTITUTION: Cellulose fibers are initially wet-laid to form a web and a polysiloxane compound in an amount capable of retaining the polysiloxane in an amount of 0.004-0.75% based on the dry fiber weight of the resultant tissue paper in the web is then applied to the web when the fiber consistency of the web is 10-80% based on the total web weight. The resultant web is subsequently dried and creped to produce the objective product having 10-65 g/m<2> basis weight and <=0.6 g/cc density. Furthermore, an amino-functional polydimethylpolysiloxane is preferred as the polysiloxane compound.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD This invention relates generally to a method for making tissue paper, and more particularly to a method for making tissue paper having a soft, silky, flannel-like feel and high tactile bulk and physiological surface smoothness. The present invention relates to a method for producing bulk tissue vapor.

BACKGROUND OF THE INVENTION Soft tissue papers are commonly preferred as disposable paper towels, facial and toilet tissues.

However, known methods and means for increasing the flexibility of tissue paper usually have an adverse effect on tensile strength. Therefore, in the design of tissue paper products, it is usually a challenge to balance flexibility against tensile strength.

Both mechanical and chemical means have been introduced with the aim of producing soft tissue paper, ie tissue paper that is perceived by users as soft to their touch.

Although the flexibility that can be sensed by touch is not particularly limited, elasticity, flexibility, etc.
bility) and smoothness, as well as a subjective feeling of silk or flannel. The present invention improves the quality of tissue paper, especially high quality tissue paper, by the introduction of chemical additives, particularly polysiloxane materials, which impart a silky or flannel-like feel to the tissue paper without making the tissue paper product feel sticky or crooked to the user. The present invention relates to a method for improving the tactile softness of bulk creped tissue paper. In addition, surfactants can also be added to further increase flexibility and/or surface smoothness and/or to at least partially compensate for any reduction in wettability caused by polysiloxanes; Such binder materials may also be added to at least partially compensate for the reduced strength and/or increased lintability caused by the polysiloxane and, if used, surfactant additives.

Representative high bulk creped tissue papers that are quite soft by current standards and amenable to the increased flexibility of the present invention are disclosed in the following US patents:
Lawrence H. Sanford
No. 3,301.746 dated January 31, 17, issued to James B. Sisson and Peter G. ) to 1
No. 3,974.02 dated August 10, 976
No. 5; George φ Morgan Jr.

(George Morgan, Jr.) and Thomas F. Rich (Thomas P. Rlch) 19
No. 3.994, 7 issued November 30, 1976
No. 71; Pau'l D.
No. 4,191.609 dated March 4, 1980 to Paul D. Trokhan; and No. 4.637 dated January 20, 1987 to Paul D. Trokhan.
, No. 859. Each of these vapors is characterized by a pattern of dense areas, ie, areas denser than the rest of each of them, where such dense areas are compacted during papermaking, such as by the cross-knuckles of the imprint carrier fabric. arises from something. Another high bulk soft tissue barber is Jerry E, Carstens at 198
U.S. Patent Section 4,300, issued November 17, 1999.
, No. 981; and Nidward R. Wells (Edv.
ard R. Wells) and Thomas A. Icnsler (1984).
No. 4,440,597 issued on April 3, 2007. In addition, obtaining high bulk tissue paper by avoiding gross densification before final drying has been demonstrated by D.L. Shaw.
U.S. Patent Section 3, issued June 28, 1974,
No. 821,068; the avoidance of overall densification through the combined use of debonders and elastic bonders in papermaking furnishes is disclosed in J.L. Sarputsi, Jr. (J,L
, US Pat. No. 3,812,000, issued May 21, 1974.

Chemical debonders and their theory of action, such as those considered by Salputy above, are published by Freemark (Friema).
No. 3, dated August 28, 1973,
No. 755,220; 19 to Meisel et al.
No. 3゜844.88 issued on October 29, 1974
No. 0; and Becker et al., 1979 1
No. 4,158,594, issued May 19, 2005, and in representative US patent applications such as US Pat. Other chemical treatments that have been proposed to improve tissue paper include, for example, Kenji Hara et al., West German Patent Section 3,42.
No. 0,940, i.e., impregnating toilet datesh vapor with a combination of a silicone oil, such as dimethyl silicone oil, and a vegetable, animal or synthetic hydrocarbon oil to provide cleanliness and ease of wiping. There is a way to do it.

In addition, a well-known mechanical method of increasing the tensile strength of vapor made from cellulose bulbs is by mechanically refining the bulbs before papermaking. Generally, the higher the degree of refinement, the higher the tensile strength. However, consistent with the above discussion regarding tissue tensile strength and flexibility, a high degree of mechanical refinement of the cellulose bulb will have a negative impact on the flexibility of the tissue paper, except that all other components of the papermaking furnish and process There is no change in this aspect. However, by application of the present invention, the tensile strength can be increased without adversely affecting the flexibility; on the other hand, the flexibility can also be improved without adversely affecting the tensile strength.

An object of the present invention is to provide a method for producing tissue paper with a high soft feel.

Another object of the present invention is to provide a method for producing tissue paper having a silky, flannel-like feel.

Another object of the present invention is to provide a method for producing tissue paper that has increased tactile softness at a certain level of tensile strength compared to tissue paper softened according to the prior art.

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

SUMMARY OF THE INVENTION The present invention relates to a method for making soft tissue paper. This method wets the cellulose fibers to form a web, and on a dry fiber weight basis, from about 0.004 to about 0.7
Ladle 10 to about 80% polysiloxane in a dish enough that 5% polysiloxane can be retained on tissue paper.
(based on total web weight) to the web, and then drying and creping the web. Preferably, the amount of polysiloxane retained in 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 of about 10 to about 65 g/cc and a fiber density of about 0.6 g/cc or less.

The polysiloxane is applied after the wet web is formed and before it is completely dry. Surprisingly, it was found that a great deal of tissue softening effect could be achieved with significantly lower levels of polysiloxanes when the polysiloxanes were applied to a wet web compared to a dry web (e.g. during a conversion operation). did. In fact, an important feature of the method disclosed herein is that the silicone level is sufficiently low that it is economical. Moreover, tissue paper treated with low levels of polysiloxane retains high levels of wettability, an important characteristic of tissue products.

Preferred polysiloxanes for use in the method of the invention include amino-functional polydimethylpolysiloxanes, where up to about 10 mole percent of the polymer side chains contain amino functionality. Since the molecular weight of polysiloxane is difficult to confirm, the viscosity of polysiloxane is used in the present invention as an indicator of molecular weight that can be objectively confirmed.

Thus, for example, about 2% substitution has been found to be very effective for polysiloxanes having a viscosity of about 125 centistokes, but about 5 million (5,000,
000) centistokes or higher is also effective with or without substitution. In addition to such substitutions with amino functional groups, useful substitutions include carboxyl, hydroxyl, ether, polyether, aldehyde, ketone, amide,
It is also possible to work with ester and thiol groups. Among these effective poor substituents, the group comprising amino, carboxyl and hydroxyl groups is more preferred than others, with the amino functionality being the most preferred.

Examples of commercially available polysiloxanes include Dow Conning (
Dow Corning) Dow 8075 and Dow 2
00 ; and union carbide (tlnlonC
arbide) Silwet (Si 1wet)
720 and Ukarushiruku υcars11) E P S
There is.

The method for producing tissue paper treated with polysiloxane according to the invention is designed to at least partially compensate for any reduction in the wettability of the tissue paper that would otherwise result from the introduction of the polysiloxane and/or The method may further include adding an effective amount of a surfactant to enhance tactile surface smoothness. The effective amount of surfactant is preferably such that about 0.01% to about 2%, more preferably about 0.05% to about 1.0%, based on the dry fibers of the tissue paper, are retained by the tissue paper. It's the amount. Moreover, the preferred surfactants are non-cationic so that datesch vapor can substantially avoid post-manufacturing changes in tissue paper properties that would otherwise result from the introduction of surfactants. It is virtually immobile in situ after being manufactured. This is achieved, for example, by the use of surfactants with melting points above the temperatures normally encountered during storage, transportation, merchandising, such as about 50° C. or above, and the application of tissue paper product examples of the invention.

Moreover, the method for producing tissue paper according to the invention is designed to at least partially compensate for any decrease in tensile strength or increase in linching properties that would otherwise result from 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. Preferably, the effective amount of binder material is such that from about 0.01 to about 2%, based on the dry fiber weight of the tissue, is retained in the tissue paper.

All percentages, ratios and proportions herein are according to I)1 unless otherwise indicated.

The invention is described in more detail below.

DETAILED DESCRIPTION OF THE INVENTION Briefly stated, the present invention provides tissue paper having a silky flannel-like feel and high tactile softness due to the addition of polysiloxane additives to a wet tissue web.

Such methods may further include adding to the wet web an effective amount of a surfactant and/or a binder material such as starch. Generally speaking, surfactants are included to increase the slipperiness of a tactilely perceptible physiological surface and/or to obtain sufficient wettability for the intended purpose of the tissue (e.g., toilet tissue). can be made.

Additionally, binder materials such as starch may at least partially eliminate any reduction in tissue paper tensile strength and/or deterioration in linching properties that would otherwise occur with the addition of polysiloxane and surfactant, if used. It can be included to supplement.

Surprisingly, compared to the application of polysiloxanes to dry tissue webs (e.g., during conversion operations), very low levels of polysiloxanes can be applied to wet tissue webs according to the present invention. It was found that it exerts a tissue softening effect. To ensure high retention, a wet web is formed and dewatered prior to application of the polysiloxane additive in order to reduce loss of polysiloxane due to exclusion of free water. Importantly, the level of polysiloxane used to soften datesch vapor was found to be low enough that the tissue paper could retain high wettability.

The present invention is applicable to tissue paper in general, including, but not limited to, conventional felt compressed tissue paper: patterned densified tissue paper as exemplified by Sanford-Sisson and his disciples. : and high bulk decondensed tissue papers such as those exemplified by Sarputsi. Tissue paper may be of homogeneous or multilayer construction, and tissue paper products made therefrom may also be of single or multilayer construction. Tissue paper is about 10 to about 65
Preferably, it has a basis weight of g/rrr and a density of about 0.60 g/cc or less. Preferably, the basis weight is about 35g
/rrf or less, and the density is about 0.30 g/CC or less. Most preferably, the density is about 0.04 to about 0.20 g/
It is cc.

Conventional pressed tissue paper and methods for making such vapors are known in the art. Such vapors are typically produced by depositing papermaking furnish onto a perforated forming wire. This forming wire is commonly used in the industry for fourdrinier machines (
wire.

Once the furnish is deposited onto the forming wire, it is called a web. The web is dehydrated by compressing it and dried at high temperatures. Specific techniques and typical equipment for producing webs in the manner described above are well known to those skilled in the art. In a typical method, a low consistency valve furnish is fed into a pressurized headbox. The headbox has an opening for feeding a dilute deposit of pulp furnish onto the Fourdrinier wire to form a wet web. The web is then vacuum dewatered and further dried in a compression operation in which the web is spread and pressurized with opposing mechanical parts, such as cylindrical rolls, to a
It is typically dehydrated to a fiber consistency of ~25% (based on total web weight). The dewatered web is then pressure dried in a stream drum apparatus known in the art as a Yankee dryer. Pressure can be applied in a Yankee dryer by mechanical means such as opposed cylindrical drums compressing against the web. Multiple Yankee dryer drums can be used, so that additional pressure may be created 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 forces during which the fibers are wetted and then dried in the compressed state. .

Patterned densified tissue paper is characterized by having a relatively high bulk portion of relatively low fiber density and an arrangement of dense zones of relatively high fiber density. High bulk regions, on the other hand, are characterized as pillow regions. The dense zone is the knuckle (knu) on the one hand.
ckle) It is called the 6M area. The dense zones are either separated within the high bulk portion or connected either completely or partially within the high bulk portion. A preferred method for producing patterned densified tissue webs is described in Sanford and Sisson, 1% January 7, 311.
U.S. Patent No. 3,301,746 issued on August 10, 1976 [Ball φD-]
U.S. Patent No. 4.191 issued to Rokuhan on March 4, 1980. 6o9-q, all of which are incorporated herein by reference.

Generally, patterned densified webs are produced by depositing the paper product onto a perforated forming wire, such as fourdrinier machine wire, to form a wet web and then juxtaposing the web against an array of supports. Preferably, it is manufactured.

The web is pressed against the array of supports, thereby providing dense zones in the web at locations corresponding in location to the points of contact between the array of supports and the wet web. The remainder of the web that is not compressed during this operation is referred to as the high bulk portion. Formation of the dense zone is carried out by the application of hydraulic pressure, such as by a vacuum type device or blow-through dryer, or by mechanically pressing the web against the support arrangement. The web is dewatered and optionally predried in a manner that substantially avoids compaction of the high bulk portions. This is preferably done by hydraulic pressure, such as by a vacuum-type device or a blow dryer, or alternatively by mechanically pressing the web against the support arrangement, in which the high bulk portions are not compressed. The operations of dewatering, optional pre-drying and formation of dense zones reduce the total number of processing steps carried out29
or can be partially adjusted.

After dense zone formation, dewatering and optional pre-drying, the web is preferably completely dried so that mechanical pressure can still be avoided. Preferably, about 8 to about 55% of the tissue paper surface includes dense knuckles having a relative density of at least 120% of the high bulk portion.

Preferably, the support arrangement is an imprint carrier can with a patterned replacement of the knuckles that acts as a support arrangement to promote the formation of dense zones upon pressurization. The knuckle pattern constitutes the support arrangement. The imprint carrier fabric is disclosed in U.S. Pat. Tf No. 3,821.068; U.S. Patent No. 3.9 issued August 10, 1976 to Ayers.
No. 74,025; U.S. Patent No. 3,573.164 issued to Fricdbcrg et al., dated March 30, 1971; Patent No. 3.473,576; Torokuhan 1
U.S. Patent No. 4,2, issued December 16, 1980.
No. 39.065: and U.S. 11 No. 4.528,239, issued July 9, 1985 to Trokhan, all of which are incorporated herein by reference. .

Preferably, the papermaking furnish is first formed in a wet web on a foraminous forming carrier such as Fourdrinier wire. The web is dehydrated and transferred to a printing fabric. Alternatively, the paper product may first be allowed to settle onto a perforated support carrier which also serves as a marking fabric. Once formed, the wet web is dewatered and thermally predried to a selected fiber consistency, preferably from about 40 to about 80%. Preferably, dewatering is carried out in a suction box or other vacuum device or in a blow-through dryer.

Knuckle stamps on the stamping fabric are stamped on a web as described above before the web is completely dried.

One way to do this is through mechanical pressure. This is the nip that supports the printing fabric against the surface of a drying drum, such as a Yankee dryer.
) by pressing the rolls, in which case the web is placed between the nip rolls and the drying drum. Furthermore, the web is preferably shaped to the marking fabric prior to complete drying by application of hydraulic pressure in a vacuum device such as a suction box or in a blow dryer. Hydraulic pressure is applied to imprint the dense zone during the initial dewatering, at another later process step, or a combination thereof.

Decondensed, non-patterned densified tissue paper structures were developed by Josephite Sarputsi Jr. and Beta 11.
Peter N, Ylannos
No. 3, issued May 21, 1974.
No. 812.000 - and Henry E. Beraker ()
Ienry E., Becker), Albert L.
-7 Cornell (Albert L, McConnel
l) and Richard Shutt (Rlchard 5c)
No. 4,208,459, issued June 17, 1980 to U.S. Pat. Generally, de-densified, non-pattern densified tissue paper structures are produced by depositing the paper product onto a perforated forming wire, such as fourdrinier machine wire, to form a wet web, draining the web, and then The web is produced by further removing water and creping the web without mechanical compaction until it has a fiber consistency of at least 80%. Water is removed from the web by vacuum dehydration and heat drying. The resulting structure is a soft but somewhat high bulk sheet of relatively unconsolidated fibers. The binding substance is
Preferably, it is applied to each section of the web before creping.

Papermaking fibers that can be used in the present invention include fibers typically obtained from wood bulbs. Other cellulosic fibrous bulb fibers such as cotton linters, bagasse, etc. may also be used and are considered within the scope of this invention. Synthetic fibers such as rayon, polyethylene and polypropylene fibers can also be used in combination with natural cellulose fibers.

An example of a polyethylene fiber that can be used is Pulpex, manufactured by Hercules, Inc., Wilmington, PA.
TM).

Available wood valves include chemical valves such as kraft, sulfite and sulfate valves, and mechanical valves including, for example, ground wood and thermomechanical valves and chemically modified thermomechanical valves. However, chemical valves are preferred because they can impart a superior soft feel to tissue sheets made therewith. Deciduous trees (hereinafter also referred to as “hard water”) and coniferous trees (hereinafter referred to as “hard water”)
Valves obtained from both types of wood (also called "softwood") can also be used.

In addition to paper fibers, the paper product used to create the tissue paper structure may have other components or substances added thereto that are known or later become known in the art. Probably. The type of additive desired depends on the specific end use of the tissue sheet contemplated.

For example, high wet strength is a desirable property in products such as toilet vapor, vapor towels, facial tissues, and other similar products. Therefore, in our industry “
It is usually desirable to add chemicals known as "wet strength resins" to paper products.

A general article on the types of wet strength resins used in the paper industry can be found in the TAPPI monograph series Nα292 Wet Strength in Paper and Board, Pulp and Paper Industry Technical Association (Nyo 2,1% 5). The most useful wet strength resins have typically been cationic in character. Polyamide-shrimp chlorohydrin resin is a cationic wet strength resin that has found specific use. Suitable types of such resins are both Caim (Wets
U.S. Pat. No. 772°076, all of which are incorporated herein by reference. One commercial source of useful polyamide shrimp chlorohydrin resin is Percules, Inc. of Wilmington, PR, under the trade name KymcIleTM.
Such a resin is commercially available as 557H.

Polyacrylamide resins have also found use as wet strength resins. These resins are Cosci
a) U.S. Patent Section 3,556,932, issued January 19, 1971 to Williams (V!
3,556,933, issued January 19, 1971, both of which are incorporated herein by reference.

One customer for polyacrylamide resin is American-Cyanamide Co., Stamford, Connecticut.
erlcan CyanamidCo, ), with the trade name ParezTM 631NC 1
A tough resin is commercially available.

Still other water-soluble cationic resins useful in the present invention are urea formaldehyde and melamine formaldehyde resins. More common functional groups in these multifunctional resins are nitrogen-containing groups such as amino groups and nitrogen-bonded methylol groups.

Polyethyleneimine type resins also have utility in the present invention. It will be appreciated that the addition of compounds such as the wet strength resins described above to the valve composition is optional and not necessary for the practice of this development.

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, oligomeric copolymers and other multimonomeric siloxane materials. Furthermore, 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: 5i-0- where R1 and R2 for each siloxane monomer unit are each independently any alkyl, aryl, alkenyl, alkyl, Ryl, aralkyl, cycloalkyl, halogenated hydrocarbon or other groups. Any such group may be substituted or unsubstituted.

The R1 and R2 groups of any particular monomer unit may be different from the corresponding functional groups of the next adjacent monomer unit.

Furthermore, the group may be linear or branched, or may have a cyclic structure. The groups R1 and R2 can further and each independently include, but are not limited to, siloxanes,
Other silicone functionalities such as polysiloxanes and polysilanes are also possible.

MR and R2 can also have any of a variety of organic functional groups, including, for example, alcohol, carboxylic acid, and amine functional groups.

The degree of substitution and the type of substituents have been found to influence the relative variation in soft, silky feel and hydrophilicity imparted to the tissue paper structure. Generally, the degree of soft silkiness imparted by a polysiloxane increases as the hydrophilicity of the substituted polysiloxane decreases. Amino functional polysiloxanes are particularly preferred in this invention.

Preferred polysiloxanes include linear organopolysiloxane materials of the general formula: where each R group is independently any 01-010 unsubstituted alkyl or aryl group; is any permutation C
1-010 alkyl O or an aryl group. Preferably, each RIR9 group is each independently any 01.C4 unsubstituted alkyl group. Those skilled in the art will recognize that there is no technical difference whether, for example, R9 or Rlo is a substituent.

The molar ratio of b to (a+b) is preferably from 0 to about 20%,
More preferably 0 to about 10%, most preferably about 1 to about 5%.

In one particularly preferred example, R1-R9 are methyl groups and Rlo is a substituted or unsubstituted alkyl, aryl or alkenyl group. Such materials are generally described herein as polydimethylsiloxanes with appropriate specific functional groups in the specific case. Examples of polydimethylsiloxanes include, for example, polydimethylsiloxanes, polydimethylsiloxanes having alkyl hydrocarbon R1o groups and one or more amino, carboxyl, hydroxyl, ether, polyether, aldehyde, ketone, amide, ester, thiol and/or polydimethylsiloxane. or other R1 including alkyl and alkenyl analogs of such functional groups.
There are polydimethylsiloxanes with o functional groups. For example, an amino-functional alkyl group as Rlo is an amino-functional or aminoalkyl-functional polydimethylsiloxane. This exemplary list of polydimethylsiloxanes is not meant to exclude others not specifically listed.

The viscosity of the polysiloxanes useful in this invention typically varies over a wide range, so long as the polysiloxane is flowable or can be made to be flowable upon application to tissue paper. It can vary within. This includes, but is not limited to, approximately 25 centistokes, which ranges from approximately 20,000,000 centistokes to approximately 25 centistokes.
Some have a viscosity of centistokes or higher.

High viscosity polysiloxanes that are themselves resistant to flow can be prepared, for example, by emulsifying the polysiloxane with a surfactant or by bringing the polysiloxane into solution with the aid of a solvent such as hexane, which is shown for illustrative purposes only. , can be effectively deposited onto a tissue paper web. Specific methods of applying polysiloxanes to tissue paper webs are described in further detail below.

However, without wishing to be bound by any theory of operation, it should be noted that the tactile efficacy of a polysiloxane is directly related to its average molecular weight;
It is also believed that viscosity is directly related to molecular weight.

Therefore, since it is relatively difficult to directly measure the molecular weight of polysiloxanes compared to measuring viscosity, tissue paper has high tactile responsiveness, i.e. flexibility, silkiness and flannel-like properties. The apparent operating parameters for imparting 1° and viscosity are used here.

References disclosing polysiloxanes include Geen E. U.S. Patent No. 1@2.826,551, issued March 11, 1958:
U.S. Patent No. 3,%4.500, issued June 22, 1976;
r) l:: U.S. Pat. No. 4,364.837, issued December 21, 1982; and Woolston (V
There are various specifications of British Patent No. 849,433 published on September 28, 1%0 in OOTSTON). Furthermore,
In 1984, Petrarch Fist Systems Co., Ltd.
"Silicon Compounds", pp. 181-217, published by J. Ch. 5ystens, Inc., contains numerous listings and descriptions regarding polysiloxanes in general.

The polysiloxane is applied after the wet web is formed and before it is completely dry. Paper machine wet end (we
The addition of polysiloxanes to papermaking compositions (i.e., papermaking compositions) has been found to be impractical due to the low retention levels of polysiloxanes. Therefore, in typical methods, a web is formed prior to application of the polysiloxane to reduce loss of polysiloxane due to exclusion of free water;
It is then dehydrated. The polysiloxane is preferably
In the production of conventional pressed tissue paper, the wet web is preferably added at a fiber consistency level of about 10 to about 80% (based on the weight of the wet web), and more preferably at a fiber consistency level of about 15 to about 35%. and applied to wet webs having a fiber consistency of about 20 to about 35% in the production of tissue paper by paper machines where the newly formed web is transferred from a fine mesh Fourdrinier paper machine to a relatively coarse imprint/carrier fabric. be done. The reason is that it is preferable to do this at a time when the fiber consistency is low enough that the fibers are substantially mobile during the transfer, and yet after the drainage has proceeded in the paper machine and their mobility has essentially disappeared, the polysiloxane This is because it is preferable to apply. Furthermore, the addition of polysiloxane at high fiber consistency ensures greater retention in and on the vapor,
That is, less polysiloxane is lost by the water that is removed from the web to increase its fiber consistency. Surprisingly, retention rates of greater than about 90% are 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, such as hexane, in which the polysiloxane is dissolved or miscible.

The polysiloxane may be supplied in neat form or preferably emulsified with a suitable surface-active emulsifier. Emulsified polysiloxanes are preferred for ease of application; the raw aqueous polysiloxane solution must be agitated to prevent separation into water and polysiloxane phases.

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.

Application of polysiloxane to a wet tissue paper web in both continuous and patterned distributions both fall within the scope of the present invention and meet the above criteria.

Methods for uniformly applying polysiloxane to the web include spraying and gravure printing-11. The spray is
It was found to be the most preferred because it is economical and it is easy to precisely control the amount and distribution of polysiloxane. Preferably, the aqueous mixture containing the emulsified posiloxane is sprayed onto the wet tissue web as it passes through a paper machine including, but not limited to, a pre-dryer depending on the desired fiber consistency level. Sanford-Do-Sisson (see above) either before or after the pre-dryer.
There is an overall arrangement paper making machine disclosed by. A less preferred method involves depositing the polysiloxane on the forming wire or fabric and then contacting the tissue web. Suitable equipment for spraying polysiloxane-containing liquids onto a wet web includes the V-1-B Systems Inc. (V,1-B Systems, Inc., Tucker, Georgia).
．． There is an external mix air comminution nozzle, such as a 2 mm nozzle manufactured by B. B., 5ystes, Inc.). A suitable device for printing polysiloxane-containing liquids onto a wet web is a rotogravure printer.

It is surprising that low levels of polysiloxane applied to a wet tissue paper web can impart a softened, silky, flannel-like, non-greasy feel to the tissue paper without the aid of additives such as oils or lotions. It was discovered as it should have been. Importantly, these effects can be obtained in many instances of the present invention, with high humidity levels within the desired range for toilet vapors.

Preferably, tissue paper treated with polysiloxane in accordance with the present invention contains no more than about 0.75% polysiloxane. It is an unexpected advantage of the present invention that tissue paper treated with less than about 0.75% polysiloxane could have substantial softness and silkiness effects imparted thereto with such low levels of polysiloxane. be. Generally, tissue papers having less than about 0.3% polysiloxane, preferably less than about 0.2%, can have substantially increased softness, silkiness, and flannel-like properties, with the exception of the moisture content resulting from the polysiloxane. It maintains sufficient wettability for use as a toilet vapor without requiring the addition of surfactants to compensate for any adverse effects on properties.

The minimum level of polysiloxane to be maintained in tissue paper is that level that is at least effective in imparting a tactile distinction to the vapor with respect to softness, silkiness, or flannel-like properties.

The minimum effective level depends on the specific type of sheet, application method, specific type of polysiloxane, and whether the polysiloxane is supplemented with starch, surfactants, or pond additives or treatments. fluctuate. Although there is no limit to the range of polysiloxane retention that can be applied in tissue paper, preferably at least about 0.004%, more preferably at least about 0.01%, and most preferably at least about 0.02% polysiloxane is present in tissue paper. is maintained by

Preferably, a sufficient amount of 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. When the polysiloxane is applied to one side of the tissue paper, some of it typically penetrates at least partially into the interior of the tissue paper. In a preferred example, sufficient polysiloxane to provide touch-responsiveness is permeated through the entire thickness of the tissue paper so that both surfaces can impart the effects of the polysiloxane to it.

When the polysiloxane is applied to one side of a wet tissue paper web, one method that has been found useful in promoting polysiloxane penetration to the opposite side is to apply the polysiloxane from the other side of the wet tissue paper at the point of application of the polysiloxane to the opposite side. It involves dehydrating tissue paper.

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

Tissue papers having more than about 0.3% polysiloxane are preferably treated with surfactants when considered for applications where high wettability is desired. Most preferably, a non-cationic surfactant is applied to the wet tissue paper web to obtain additional softening effects 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%
~1.0% surfactant retained in tissue paper provides high enough wetting properties for most applications, including toilet vapor, at polysiloxane levels of about 0.75% or less. The above is considered to be sufficient.

Preferred surfactants for the present invention are non-cationic;
More preferably, it is nonionic. However, cationic surfactants can also be used. Non-cationic surfactants include anionic, nonionic, amphoteric and zwitterionic surfactants. Preferably, the surfactant, as described above, is such that the tissue paper is manufactured in a manner that substantially avoids post-manufacturing changes in the properties of the tissue paper that would otherwise result from the introduction of the surfactant. It is then virtually immobile in situ.

This is achieved, for example, by the use of surfactants with melting points above the temperatures normally encountered during storage, transportation, merchandising, eg, with a furrow point above about 50° C., and application of the tissue paper product examples of the present invention. Additionally, it is preferred that the surfactant is water soluble when applied to a wet web.

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

Preferably, the surfactant has an alkyl chain of 8 or more carbon atoms. Examples of anionic surfactants include linear alkyl sulfonates and alkylbenzene sulfonates. Examples of nonionic surfactants include:
Croda.

Alkyl glycoside esters such as "Crodesta") S L-40, manufactured by New York, New York, Inc.), Langton (d
, K.

Clyco Chemicals, as described in U.S. Pat. No. 4,011,389 issued March 8, 1977 to
Examples of alkyl glycosides include alkyl polyethoxylated esters, such as Pegosperse™ 200 ML manufactured by Pegosperse Inc., Greenwich, Conn.). Alkyl polyglycosides are particularly preferred for use in the present invention. The above list of exemplified surfactants is merely illustrative of the types and is not meant to limit the scope of the invention.

The surfactant, in addition to any emulsifying surfactant that may be present on the polysiloxane, can be applied with similar methods and equipment used to apply polysiloxanes. These methods include spray and gravure printing. Preferably, the surfactant-containing aqueous mixture is sprayed onto the wet tissue web as it passes through the paper machine. Other methods include applying it to the forming wire or fabric before contacting the web.

Any surfactant other than the polysiloxane emulsifying surfactant is hereinafter referred to as a "surfactant" and any surfactant present as an emulsifying component of the emulsifying polysiloxane is hereinafter referred to as an "emulsifier."

The surfactant is applied to the tissue paper at the same time, after or before the polysiloxane.

In a typical process, surfactants are applied after formation of the wet web and before final drying. The surfactant is preferably about 10 to about 80%, more preferably about 15 to about 35%.
applied to a wet tissue web at a fiber consistency level of . Surprisingly, the retention of non-cationic surfactants applied to the wet web is high even when it is applied under conditions where the surfactant is not ionically substantial to the fibers. Retention rates in excess of about 90% are expected at preferred fiber consistency without the use of chemical retention aids.

As mentioned above, it is also desirable to treat polysiloxane-containing tissue papers with relatively low levels of binder for lint control and/or to increase tensile strength. “Binder” as used herein
The term relates to a variety of wet and dry strength additives known in the art. The binder is applied to the tissue paper at the same time, after or before the polysiloxane and the surfactant, if used. The binder is
Preferably about 10 to about 80%, more preferably about 15 to about 80%
It is added to the wet tissue web at a fiber consistency level of approximately 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 moist at the time of application. In addition to reducing linching in the final Tissinivaber product, even low levels of starch reduce the boardiness (i.e., stiffness) that would result from high levels of starch addition.
Provides moderate improvement in tensile strength of tissue paper without imparting. It further provides improved strength compared to conventionally reinforced tissue papers that increase tensile strength, e.g. sheets with higher tensile strength due to increased pulp refinement or addition of other dry strength additives. /A tissue paper having flexibility is obtained. This result is particularly surprising. This is because starch has traditionally been used to provide strength at the expense of flexibility in applications where flexibility is not an important characteristic, such as paperboard. Additionally, starch has been used as a printing and writing vapor filler to improve surface printability.

Generally, starches suitable for the practice of this invention are characterized by water solubility and hydrophilicity. Examples of starch materials include corn starch and potato starch, without thereby intending to limit the range of suitable starch materials, and waxy corn starch, known commercially as amloca starch, is particularly preferred. Amioca starch differs from regular corn starch in that it is all amylopectin, whereas regular corn starch contains both amylopectin and amylose. The various unique characteristics of Amioca starch are:
“Ami-Kai-Starch from Waxy Corn”, H,1
(, Schopmair (II, II, Schopm
eyeer), Food Industries (FoodI
industries), December 1945, No. 1
Further discussion is provided on pages 06-108 (pages 1476-1478).

The starch may be in granular or dispersed form, although granular form is preferred. Preferably, the starch is sufficiently cooked to induce expansion of the granules.

More preferably, the starch granules are expanded, such as by cooking, immediately before dispersing the starch granules. Such highly expanded starch granules are referred to as "fully cooked." Dispersion conditions usually vary depending on the size of the starch granules, the crystallinity of the granules and the amount of amylose present. Fully cooked Amioca starch can be made, for example, from an aqueous slurry of starch granules of about 4% consistency.
It can be produced by heating at about 88° C. for about 30 to about 40 minutes.

Examples of other starch materials that can be used include National Starch and Chemical Co. (NaLiona!
There are modified cationic starches such as those manufactured by Mical Company (Bridgewater, New Jersey). Such modified starch materials have been used primarily as valve composition additives to enhance wet and/or dry strength.

However, when applied according to the present invention by application to a wet tissue paper web, they will be less effective on wet strength compared to wet end additions of similar modified starch materials. Given that such modified starch materials are more expensive than unmodified starches, the latter was usually preferred.

The starch must be applied to the tissue while the vapor is still wet. The starch matrix material is preferably added to the wet Tissini Baber web when the web has a fiber consistency of about 8090 or less. The non-cationic starch material is retained in the web sufficiently to have an observable effect on flexibility at a particular strength level even with increased refinement, preferably from about 10% to about 80%, more preferably from about 15%. Applied to a wet tissue web with a fiber consistency of ~35%.

Preferably, the starch is applied to the tissue paper web as an aqueous solution. Application methods include the same methods as described above for polysiloxane applications, preferably by spraying, less preferably by printing. The starch is applied to the tissue paper web at the same time, before or after the addition of the polysiloxane and/or surfactant.

At least except for the fact that it is not binder processed.
binder in an amount effective to increase lint control and concomitant strength when dry compared to sheets of
Preferably starch is applied to the sheet. Preferably from about 0.01 to about 2.0% binder is retained in the dryer sheet, more preferably from about 0.1 to about 1.0% binder material, preferably from about 0.01 to about 2.0%, calculated on a dry fiber weight basis. The starch matrix is retained.

Analysis of the amount of treatment chemical retained in the tissue paper web can be performed by any method accepted in the application industry. For example, the level of polysiloxane retained by tissue paper can be determined by solvent extraction of the polysiloxane with an organic solvent, followed by atomic absorption spectroscopy to determine the silicon level in the extract.
ν1 determined: Levels of nonionic surfactants such as alkyl glycosides are determined by extraction with organic solvents followed by gas chromatography to examine surfactant levels in the extract: linear alkyl sulfonates. Levels of anionic surfactants were determined by water extraction followed by colorimetric analysis of the extract; levels of starch were determined by amylase digestion of starch to glucose followed by colorimetry to determine glucose levels. Ru. These methods are exemplary and are not meant to exclude other methods useful for determining the levels of particular components retained by tissue paper.

The hydrophilicity of tissue paper refers to the tendency of the tissue paper to become wetted with normal water. The hydrophilicity of tissue paper may be quantified somewhat by measuring the time required for dry tissue paper to become completely wetted with water. This time is called the "wetting time".

In order to provide a test method that is consistent and repeatable with respect to wetting time, the following procedure is used for wetting time measurements; first, about 4-3/8 x 4-3 inches (about 11.
A dry (fiber consistency level greater than 90%) sample unit sheet of a tissue paper structure of 1 x 12 mm is prepared; second, the sheet is folded in parallel in quarters so that the rear diameter is approximately 0.75 inch (approximately 1.5 mm). 9cm) ~ approx. 1
Mush into 2.5 inch balls: Third, the ball sheets are placed on a surface of 72'F distilled water and a timer is set at the same time; Fourth, the timer is stopped and read when wetting of the ball sheet is complete. Completion of wetting is visually observed.

The preferred hydrophilicity of tissue paper depends on its intended end use. In the case of tissue paper used in various applications, such as toilet vapor, complete wetting is desired in a relatively short period of time in order to prevent clogging when draining the toilet. Preferably the wetting time is 2 minutes or less. More preferably,
Wetting time is 30 seconds or less. Most preferably, the wetting time is 10 seconds or less.

The hydrophilic properties of the tissue paper examples of the invention can of course be determined immediately after production. However, a substantial increase in hydrophilicity occurs in the first two weeks after the tissue paper is manufactured, ie after the vapor is two weeks old after its manufacture. Therefore, it is preferred that the wetting time is measured at the end of such two-week period. Therefore, the wet time measured after two weeks at room temperature is referred to as the "two week wet time."

The density of tissue paper, as that term is used herein, is the average density calculated as the basis weight of the vapor divided by the caliper (cat 1 per), where appropriate unit conversions are made. Ru. The tissue paper caliper used herein is 95
This is the thickness of vapor when subjected to a compressive load of g/in2 (15.5 g/cj).

Example 1 The purpose of this example is to illustrate one method that can be used to produce soft tissue paper sheets treated with polysiloxane in accordance with the present invention.

A pilot scale fourdrinier paper machine is used in the practice of the present invention. The paper machine has a laminated headbox with a top chamber, a middle chamber and a bottom chamber. Where applicable, as shown in the examples below, the operations described below also apply in such later examples. Briefly, a first fiber slurry consisting mainly of rectangular paper fibers is pumped from the top and bottom headbox chambers, and at the same time a second fiber slurry consisting mainly of long-cut paper fibers is pumped from the central headbox chamber. and fed onto the top of the Fourdrinier machine wire to form a three-layer initial web thereon. The first slurry has a fiber consistency of about 0.11% and its fiber content is Eucalyptus Iardvood.
Krart). The Nisslary has a fiber consistency of approximately 0.15% and its fiber content is Northern Softwood Kraft.
Kraft). Dewatering occurs via fourdrinier wire and is assisted by a deflector and vacuum box. The long paper machine wire is 5 shed and the sash weave arrangement each has 87 machine direction and 76 cross machine direction filaments per inch. The initially wet web is transferred from the fourdrinier wire at a fiber consistency of about 22% to a carrier fabric having a 5-sheet weave of single fibers of 35 machine directions and 33 cross machine directions per inch, respectively. . The non-fabric side of the web is sprayed with an aqueous solution containing an emulsified polysiloxane composition as described below from two spray nozzles located on opposite sides of the vacuum dehydration box. The wet web is approximately 22% (total web ff1ffi) when sprayed with an aqueous solution.
tJA II consistency (base). The sprayed web is conveyed on a carrier fabric through a vacuum dewatering box and then blow-through.
A 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 dehydration box,
Approximately 65% before being transferred onto the Yankee dryer by the action of the pre-dryer; polyvinyl alcohol 0
．． A 25% aqueous creped adhesive is spray applied with an applicator; the fiber consistency increases to an estimated 99% before dry creping the web with a doctor blade. The doctor blade has an inclination angle of approximately 24rR and is placed at an impact angle of approximately 83 degrees to the Yankee dryer; the Yankee dryer is approximately 8001'pm.
(feet 7 minutes) (approximately 244 m/min). The dry creped web is then passed between two calender rolls. The two calender rolls are offset from each other in roll weight and are operated at a surface speed of 660 f'pm (approximately 201 m/min).

The aqueous solution sprayed from the spray nozzle onto the wet web contains 0.71% by weight Dow Corning Q2-722.
4 (a 35% nonionic emulsion of amino-functional polydimethylpolysiloxane manufactured by Dow Corning). The volumetric flow rate of the aqueous solution from the nozzle is approximately 3
Gallon/hr-tM direction ft (approx. 374!/hr・
m). Retention of polysiloxane applied to the web is typically about 90%.

The resulting tissue paper has a base M content of 30 g/rf, a density of 0.10 g/cc, and contains 0.025% by weight of amino-functional polydimethylpolysiloxane compound.

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

Example 2 The purpose of this example is that the tissue paper is polysiloxane
One method that can be used to produce soft tissue paper sheets treated with surfactants and starch is to be described.

A three-layer paper sheet is prepared according to the method of Example 1 above. In addition to treatment with the polysiloxane compound, the tissue web was also treated with Clodesta 5L-40 (an alkyl glycoside polyester nonionic surfactant manufactured by Croda) and fully cooked amiocadenbum prepared as described above in the specification. It is processed. The surfactant and starch are applied simultaneously with the emulsified polysiloxane composition as part of an aqueous solution sprayed from a paper machine spray nozzle. Clodesta 5L-4 in aqueous solution
The nonionic surfactant concentration is adjusted so that the level of surfactant retained is about 0.15% based on dry fiber weight. Similarly, the concentration of starch in an aqueous solution is
The level of amiocadene retained is adjusted to be about 0.2% based on dry fiber weight.

The resulting tissue paper had a basis weight of 30 g/rrl', a density of 0.10 g/cc, 0.025 wt% Dow Q2-7224 polydimethylpolysiloxane, 0.15 wt% Clodesta 5L- 40 nonionic surfactant and 0.40 nonionic surfactant. Contains 2ffl% cooked amiocadenbun. Importantly, the resulting datesch vapor has a silky, flannel-like feel and high tactile softness, as well as higher wettability and lower lint properties than tissue paper treated with polysiloxane compositions alone. This is what we are doing.

Claims (1)

Claims: 1. A method for producing soft tissue paper, comprising: a) wet-depositing cellulose fibers to form a web; applying a polysiloxane compound to the web at a fiber consistency of from about 10 to about 80%, based on total web weight, in an amount sufficient to allow about 0.75% of the polysiloxane to be retained in the web; and c) drying and creping the web (wherein the tissue paper has a basis weight of about 10 to about 65 g/m^3 and a density of about 0.60 g/cc or less). 2. The method of claim 1, wherein about 0.004 to about 0.3% polysiloxane is retained in the web. 3. Polysiloxane is amino, carboxyl, hydroxyl, ether, polyether, aldehyde, ketone,
2. A polydimethylpolysiloxane having hydrogen-bonding functional groups selected from the group consisting of amide, ester, and thiol groups, wherein said hydrogen-bonding functional groups are present at a substitution molar percentage of about 20% or less. the method of. 4. The method of claim 3, wherein the polysiloxane has a molar substitution of about 10% or less and a viscosity of about 25 centistokes or more. 5. The method of claim 3, wherein the polysiloxane has a molar substitution of about 1.0 to about 5% and a viscosity of about 25 to about 20,000,000 centistokes. 6. The method of claim 3, wherein the substitution molar percentage is about 2% and the viscosity is about 125 centistokes. 7. The method according to claim 3, wherein the hydrogen bonding functional group is an amino functional group. 8. The method of claim 1, wherein the polysiloxane is applied to the web when the web has a fiber consistency of about 15% to about 35%. 9. Approximately 0.0% based on the dry fiber weight of tissue paper.
applying a water-soluble surfactant to the web at a fiber consistency of from about 10 to about 80%, based on total web weight, in an amount sufficient to allow 0.01 to about 2.0% surfactant to be retained in the web; 2. The method of claim 1, further comprising: 10. Claim 9, wherein the amount of surfactant is from about 0.05 to about 1.0% based on the dry fiber weight of the tissue paper.
The method described in. 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 of claim 9, wherein the surfactant has a melting point of at least about 50<0>C. 14. Approximately 0 relative to the dry fiber weight of tissue paper
．． 1 . The method of claim 1 , further comprising applying a sufficient amount of binder to the web at a fiber consistency of from about 10 to about 80%, based on total web weight, such that 0.01 to about 2.0% binder can be retained in the web. The method described in. 15. The method of claim 14, wherein the binder is starch. 16. Approximately 0 relative to the dry fiber weight of tissue paper
．． 16. The method of claim 15, wherein 1 to about 1.0% starch is retained in the web. 17. Claim 15, wherein the starch is amioca starch.
The method described in. 18. Approximately 0 relative to the dry fiber weight of tissue paper
．． 10. The method of claim 9, further comprising applying a sufficient amount of binder to the web at a fiber consistency of from about 10 to about 80%, based on total web weight, such that from 0.01 to about 2.0% binder can be retained in the web. The method described in. 19. The method of claim 18, wherein the surfactant is non-cationic and the binder is starch. 20. A product manufactured by the method according to claim 1. 21. A product manufactured by the method according to claim 5. 22. A product manufactured by the method according to claim 9. 23. A product manufactured by the method according to claim 14. 24. A product manufactured by the method according to claim 18. 25. A product manufactured by the method according to claim 19.