JP5930639B2 - Sanitary tissue paper and method for producing sanitary tissue paper - Google Patents

Description

  The present invention relates to a sanitary thin paper and a method for producing a sanitary thin paper.

  In recent years, healthy ingredients such as vegetables and tofu have been favored due to growing health consciousness, and hygienic thin paper such as kitchen paper used for draining such wet ingredients and wiping around the kitchen has excellent water absorption. The demand for things is increasing.

For example, Patent Literature 1 proposes a sanitary thin paper that can absorb water efficiently by forming one surface side as a high water absorption layer and forming the other surface side as a low water absorption layer. Such a configuration is realized by means such as making a difference in fiber density between one side of the paper and the other side, or making a difference in the amount of binder contained.
However, since the technique of Patent Document 1 is a technique that enables efficient water absorption due to a difference in water absorption speed between the high water absorption layer and the low water absorption layer, the essential water absorption amount of the sanitary thin paper is increased. It is not a thing.

By the way, conventionally, in a paper diaper, a sanitary napkin, and the like, a technique using a highly water-absorbent resin for increasing the water absorption amount is known.
As the superabsorbent resin, for example, granules made of sodium polyacrylate or the like are used. In a paper diaper or the like, the end of the sheet is sandwiched between the superabsorbent resins so as to be dispersed between the sheets. The parts are heat sealed.

JP-A-11-244188

However, in the sanitary thin paper, as in the paper diaper described above, the superabsorbent resin is dispersed between the sheet materials constituting the sanitary thin paper, and the end portions of the sheet material are sandwiched between the superabsorbent resins. It is technically difficult to completely seal and prevent scattering of the powder of the superabsorbent resin, and even if it can be completely sealed, the superabsorbent resin is biased during use, causing problems in use. is there.
In addition, when the superabsorbent resin is fixed to the sheet material by using an adhesive or the like, the superabsorbent resin solidifies the solid content of the superabsorbent resin and inhibits the superabsorbent resin to absorb water. The water absorbing property of the water absorbing resin cannot be fully utilized.
In this way, the powdery or granular superabsorbent resin is dispersed and fixed uniformly on the sheet material constituting the sanitary thin paper, and the superabsorbent resin has sufficient water absorbency when the sanitary thin paper is used. Sanitary tissue paper that can be expressed in the world has not been developed yet.

  An object of the present invention is to provide a sanitary thin paper having high water absorption and a method for producing the sanitary thin paper.

To solve the above issues,
The invention according to claim 1 is a sanitary thin paper,
A first sheet material;
A second sheet material laminated on the first sheet material,
At least one of the inner surface of the first sheet material and the inner surface of the second sheet material is coated with a resin dispersion obtained by dispersing a superabsorbent resin in a medium liquid,
The liquid medium is water, a polyol, and I viscous liquid der containing a water blocking agent that prevents the absorption of water of the high water-absorbent resin, the water blocking agent, of saturated with the liquid medium in sodium chloride Or it is potassium chloride, It is characterized by the above-mentioned.

The invention according to claim 2 is the sanitary thin paper according to claim 1 ,
Wherein the first sheet material and the second sheet material, characterized in that the embossing is applied.

The invention according to claim 3
A method for producing sanitary thin paper for producing the sanitary thin paper according to claim 1,
Water, polyols, and the liquid medium containing the water blocking agent that prevents the absorption of moisture superabsorbent polymer, by dispersing super absorbent resin, and the resin dispersion preparing step of preparing a resin dispersion,
An application step of applying the resin dispersion prepared in the resin dispersion preparation step to one surface of the first sheet material and / or the second sheet material;
A bonding step in which the first sheet material and the second sheet material to which the resin dispersion is applied by the application step are bonded together with the application surface of the resin dispersion as an inner surface;
It is characterized by having.

According to the present invention, a water-based viscous lotion liquid containing water and polyol as a main component contains sodium chloride, potassium chloride, or the like that suppresses the osmotic pressure of the superabsorbent resin and prevents water absorption. Thus, it becomes a monovalent metal ion and acts as a water absorption inhibitor, and a resin dispersion in which a highly water-absorbent resin is uniformly dispersed in a medium liquid can be formed. By applying this to the sheet material, the superabsorbent resin can be uniformly dispersed and fixed to the sheet material constituting the sanitary thin paper without swelling.
When the laminated sheet material absorbs moisture, moisture is absorbed from the surface of the sheet material to the inside, the amount of moisture in the medium liquid applied inside the sheet material increases, and the salinity concentration around the dispersed superabsorbent resin Is lowered and the osmotic pressure of the highly water-absorbent resin is increased, so that the water-absorbing property of the highly water-absorbent resin is expressed.
In addition, the above resin dispersion is mainly composed of water and polyol, and its viscosity and moisture retention are not changed by salt (water absorption inhibitor). Therefore, the touch of sanitary thin paper should be softened and comfortable to wipe. it can.

It is an external view of the sanitary thin paper of this invention. It is sectional drawing of the sanitary thin paper of FIG. It is a flowchart which shows the manufacturing method of the sanitary thin paper of this invention.

  Hereinafter, embodiments of the sanitary thin paper according to the present invention will be described in detail. In the embodiment according to the present invention, sanitary thin paper is described as kitchen paper.

First, the configuration will be described.
As shown in FIG. 1, the kitchen paper 10 in the present embodiment is obtained by laminating and integrating two sheet materials (first sheet material, second sheet material) 11 and 12.
Since at least one of the inner surfaces of the two sheet materials 11 and 12 is coated with a resin dispersion 13 (described later), the kitchen paper 10 has two sheet materials in a sectional view as shown in FIG. The resin dispersion liquid 13 is interposed between 11 and 12.

The sheet materials 11 and 12 are made from raw material pulp in which at least one of softwood kraft pulp (NBKP) and hardwood kraft pulp (LBKP) is blended.
The softwood which is the raw material of NBKP has a fiber length twice or more longer than that of hardwood. Therefore, by blending NBKP, the bond between fibers is strengthened, and the strength (paper strength) of the paper substrate can be increased.
Hardwood, the raw material of LBKP, has a short fiber length. Therefore, by blending LBKP, the surface of the paper substrate becomes smooth and the formation can be improved.
Therefore, it is preferable that the blending ratio of NBKP and LBKP is appropriately set according to the characteristics that the kitchen paper 10 should have. That is, it is effective to increase the blending ratio of NBKP to improve paper strength, and to increase the blending ratio of LBKP to improve smoothness.

  Further, as the raw material pulp, not only chemical pulps such as NBKP and LBKP but also other suitable pulps can be used. For example, unbleached softwood kraft pulp (NUKP), unbleached hardwood kraft pulp (LUKP), waste paper pulp (DIP), non-wood pulp (eg, kenaf, manila hemp, bagasse, cotton linter, etc.), mechanical pulp (eg, , Thermomechanical pulp: TMP, chemithermomechanical pulp: CTMP, decolorized chemothermomechanical pulp: BCTMP, and the like.

10-50 g / m < ² > of the rice tsubo of the sheet materials 11 and 12 is preferable. In addition, the measuring method of a tsubo is a measuring method according to JIS P8124 (1998). When the weight per square meter is less than 10 g / m ² , the sheet materials 11 and 12 become thin, which makes it difficult to break the sheet and absorb the absorption performance. On the other hand, if the rice tsubo exceeds 50 g / m ² , the sheet materials 11 and 12 themselves become hard and the feeling of use decreases. In recent years, IH cooking heaters have become widespread, and there is a user's request to wipe lightly without damaging the heater surface.

  The sheet materials 11 and 12 are preferably embossed. By performing embossing, an uneven space for absorbing and retaining moisture and oil is formed, so that the amount of absorption can be increased.

  Such sheet materials 11 and 12 can be manufactured by a known wet method. That is, the sheet materials 11 and 12 are a paper material adjusting step for adjusting a paper material which is a suspension of fibers (raw material pulp) from the raw material, and a raw material pulp is made from the paper material to form a fiber web. And a papermaking process for drying the fiber web.

  The resin dispersion 13 is obtained by dispersing a superabsorbent polymer (SAP) in the following medium liquid.

The medium liquid is a viscous liquid containing a monovalent metal salt typified by moisture, polyol, and sodium chloride. Among the monovalent metal salts, sodium salts and potassium salts are preferable from the viewpoint of versatility and economy. A divalent metal salt such as calcium chloride is not suitable for the present invention because a sufficient water absorption cannot be obtained because a cross-linking reaction occurs inside the superabsorbent resin.
Specifically, the liquid medium is composed mainly of raw materials such as liquid oily components that are liquid at room temperature (25 ° C.) represented by water and glycerin, and a monovalent metal salt such as sodium chloride is added thereto. Has been configured. In addition to this, ingredients that are safe even when touched by ingredients such as moisturizing ingredients can be blended as appropriate. In addition, the water | moisture content contained in a medium liquid is about 10 weight%.
Due to the viscosity of this medium liquid, SAP is stably dispersed when SAP is added to the medium liquid. Moreover, the kitchen paper 10 becomes soft and flexible by applying the resin dispersion liquid 13 containing the medium liquid to the sheet materials 11 and 12.

Here, sodium chloride is a water absorption inhibitor that prevents the absorption of water in the medium liquid of SAP. For example, about 3.6 g is added to 10 g of water in the medium liquid, and is saturated in the medium liquid. It has become.
That is, by making sodium chloride saturated in the medium solution, when SAP is added to the medium solution, the SAP can be prevented from swelling due to moisture in the medium solution at that time. If sodium chloride is insufficient, when SAP is added to the medium solution, SAP absorbs too much water in the medium solution, and thus the viscosity of the medium solution increases.
As a water absorption inhibitor, sodium chloride is most preferably used because it has a low solubility in water and is less affected by temperature, but potassium chloride may be used instead of sodium chloride.

  For example, SAP is mainly a polymer of acrylic acid or acrylate, or a copolymer thereof, but if it is specifically listed together with other polymers that can be used, for example, poly (meth) acrylic In addition to a water-soluble ethylenically unsaturated polymer comprising an acid salt or a salt thereof as a main component and optionally adding a crosslinking agent, a crosslinked product of polyethylene oxide, polyvinylpyrrolidone, sulfonated polystyrene and polyvinylpyridine, starch-poly ( Saponified product of (meth) acrylonitrile graft copolymer, starch-poly (meth) acrylic acid (and its salt) graft copolymer (and its cross-linked product), starch-poly (meth) acrylic ester graft copolymer (and its) Cross-linked product), hydrolyzate of starch-poly (meth) acrylic ester graft polymer, etc. It is. Moreover, a polyvinyl alcohol sulfonate, a polyvinyl alcohol-acrylic acid graft copolymer, etc. can be illustrated. Preferably, it is a polymer of a water-soluble ethylenically unsaturated monomer mainly composed of acrylic acid or acrylate, or a cross-linked product thereof.

The SAP preferably has an average particle size of 50 to 300 μm in consideration of dispersibility in the medium liquid. If the average particle size is larger than 300 μm, it tends to sink in the medium liquid. On the other hand, if the average particle size is less than 50 μm, it absorbs moisture in the medium liquid and increases the viscosity.
The average particle diameter of the SAP powder was measured in a solvent by a dynamic light scattering method (light source: He—Ne laser, measurement temperature: 25 ° C., solvent: cyclohexane), and obtained by weight average.
Moreover, it is preferable that content in the medium liquid of SAP is 0.01-30 weight%. If the SAP content is less than 0.01% by weight, the effect cannot be obtained. On the other hand, if the SAP content is more than 30% by weight, precipitation and secondary agglomeration increase, and the coating becomes unstable due to dirt in the piping.

Moreover, as a manufacturing method of SAP, two types, the aqueous solution polymerization method (crushing method) and the reverse phase suspension polymerization method, are mentioned.
The aqueous solution polymerization method is a method in which an aqueous monomer solution is polymerized, and the gelated material is dried and then pulverized. The feature of this aqueous solution polymerization method is that the polymerization is performed from the raw material monomer, so that the degree of polymerization can be adjusted. Therefore, by extending the polymerization, the molecular weight can be increased and a polymer having high water absorption can be synthesized.
The reverse phase suspension polymerization method is a method for producing a pearl-like polymer by dispersing monomer water droplets in an organic solvent and stirring them. The characteristics of this reversed-phase suspension polymerization method are that, firstly, the particles are connected to each other, so that the particle surface area is large and the water absorption speed is high. The distribution is stable, and a polymer with high quality accuracy such as water absorption amount and water absorption speed can be produced.
In addition, although the above-mentioned two methods are mentioned as a manufacturing method of SAP, in order to raise water absorption power more, the aqueous solution polymerization method is preferable.

The coating rate of the sheet material of the resin dispersion 13 with respect to the rice floor is preferably 4.5 to 35%.
If the coating rate is greater than 35%, it is presumed that the paper strength is significantly attenuated and it is difficult to roll.
The grounds for setting the coating rate to 4.5% or more are as follows. When the content of the SAP in the medium liquid is set to 30% by weight and the necessary amount of SAP is 0.3 g, the total amount of the medium liquid and the SAP is 1.0 g. Here, when the US basis weight of the sheet material is 22 g / m ² , 1.0 / 22 = 4.5.

Here, the manufacturing method of the kitchen paper 10 is demonstrated.
As shown in FIG. 3, the kitchen paper 10 is manufactured by a manufacturing method including a resin dispersion creating process (step S1), an application process (step S2), and a bonding process (step S3).

The resin dispersion creating process (step S1) is a process for creating the resin dispersion 13 by dispersing SAP in the medium liquid.
First, the above-described granular SAP and medium liquid are prepared. Next, a predetermined amount of SAP is added to the medium liquid and uniformly dispersed therein, thereby creating a resin dispersion liquid 13.

The applying process (step S2) is a process of applying the resin dispersion 13 created in the resin dispersion creating process (step S1) to one surface of the sheet material 11 and / or the sheet material 12.
Thereby, the granular SAP dispersed in the resin dispersion 13 is uniformly distributed on one surface of the sheet material 11 and / or the sheet material 12.

In the bonding step (step S3), the sheet material 11 and the sheet material 12 to which the resin dispersion 13 is applied in the application step (step S2) are applied to the inner surface of the application surface of the resin dispersion 13 and laminated glue. It is a process of bonding.
Thereby, the kitchen paper 10 is manufactured.

Next, the operation will be described.
In the kitchen paper 10 of the present embodiment, the SAP is dispersed in the sheet materials 11 and 12 without being swollen by using the resin dispersion 13 in which SAP is dispersed in the medium liquid having the above composition. It is fixed.
And in this kitchen paper 10, when it is used for draining a foodstuff with a lot of moisture or when it is used for wiping around the kitchen, the moisture that has permeated through the sheet materials 11 and 12 is dispersed in the resin dispersion 13. Absorbed and retained by SAP.
Since SAP has a water absorption power more than ten times its own weight and is difficult to separate even when pressure is applied, the water absorption power of the kitchen paper 10 is remarkably improved as compared with that without SAP.
Further, since SAP swells by absorbing moisture, it is difficult for moisture to break through and the kitchen paper 10 is not easily torn.
In addition, the kitchen paper 10 is soft to the touch and comfortable to wipe by using the medium liquid having the above composition.

As described above, according to this embodiment, the kitchen paper 10 includes the sheet materials 11 and 12, and the resin dispersion liquid in which SAP is dispersed in the medium liquid on at least one inner surface of the sheet materials 11 and 12. 13 is applied, and the medium liquid is a viscous liquid containing water, a polyol, and sodium chloride as a water absorption inhibitor that prevents absorption of water in SAP.
By using the resin dispersion 13 in which SAP is dispersed in the medium liquid having the above-described composition, the SAP can be fixed to the sheet materials 11 and 12 constituting the kitchen paper 10 so as to be dispersed without swelling. it can.
Moreover, since the kitchen paper 10 will exhibit the water absorptivity which SAP has when water | moisture content is absorbed, the highly water-absorbing kitchen paper is realizable. Thereby, it is possible to reduce the usage-amount of the kitchen paper per time.
Moreover, the touch of the kitchen paper 10 can be made soft by using the above-mentioned resin dispersion liquid 13, and it can be set as the thing which is comfortable to wipe.

Further, according to the present embodiment, the sheet materials 11 and 12 are embossed.
For this reason, since the uneven | corrugated space which absorbs and hold | maintains a water | moisture content and an oil component is formed in the sheet | seat materials 11 and 12, when absorbing a water | moisture content, absorption amount can be enlarged.

In addition, according to the present embodiment, the resin dispersion creating step (step S1) for creating the resin dispersion 13 by dispersing SAP in the medium liquid, and the created resin dispersion 13 are used as the sheet material 11 and / or the sheet. An application process (step S2) for applying to one surface of the material 12, and a bonding process for bonding the sheet material 11 to which the resin dispersion 13 is applied and the sheet material 12 with the application surface of the resin dispersion 13 as an inner surface ( The kitchen paper 10 is manufactured by the manufacturing method which has step S3).
For this reason, granular SAP can be applied (fixed) so as to be dispersed in the sheet material 11 without swelling, and the kitchen paper 10 having high SAP water absorption can be manufactured.

[Example]
Next, examples of kitchen paper according to the present invention described above will be described together with comparative examples.

As Examples 1 to 3, application rate of the resin dispersions for the basis weight of the sheet material [g / ^{m 2]} [%], the coating amount of resin dispersion [g / ^{m 2],} SPA content [g / ^{m 2} ] Prepared kitchen paper having the values shown in Table 1, and measured the amount of water absorption.
Moreover, as Comparative Example 1, a kitchen paper to which no resin dispersion was applied was prepared, and the water absorption was measured.

In addition, as for the kitchen paper of Examples 1-3 and the comparative example 1, all used the sheet material of 22 g / m < ² > of rice basis weight with which NBKP80% and LBKP20% were mix | blended, and 2 ply bonding was performed with the lamination paste. Is.
The resin dispersion was adjusted to a particle size of 50 to 300 μm by adding 3.6 g of sodium chloride to 100 g of a medium liquid having a water content of 10% (active ingredient 90%, viscosity 86.5 mPa · s). It is the one with 5.5g of SAP added.

Moreover, after measuring the weight of the dry sample (each kitchen paper of Examples 1-3 and Comparative Example 1) cut into 100 mm square, the water absorption amount was sufficiently immersed in pure water, The weight after 30 seconds of lifting from the water was measured, and the value obtained by subtracting the weight in the dry state from the measured value was taken as the water absorption.
Moreover, the water absorption shown in Table 1 is obtained by measuring the above three times for each of the kitchen papers of Examples 1 to 3 and Comparative Example 1, and taking the average value.

<Result>
From Example 1 and Comparative Example 1, it can be seen that when a resin dispersion having an SAP content of about 0.3 g / m ² was applied, the absorption increased by about 170 g / m ² .
Moreover, from Example 2 and Comparative Example 1, it can be seen that when a resin dispersion having an SAP content of about 0.4 g / m ² was applied, the absorption increased by about 190 g / m ² .
Further, from Example 3 and Comparative Example 1, it can be seen that when a resin dispersion having an SAP content of about 0.6 g / m ² was applied, the absorption increased by about 230 g / m ² .

10 Kitchen paper 11 Sheet material (first sheet material)
12 Sheet material (second sheet material)
13 Resin dispersion

Claims (3)

A first sheet material;
A second sheet material laminated on the first sheet material,
At least one of the inner surface of the first sheet material and the inner surface of the second sheet material is coated with a resin dispersion obtained by dispersing a superabsorbent resin in a medium liquid,
The liquid medium is water, a polyol, and I viscous liquid der containing a water blocking agent that prevents the absorption of water of the high water-absorbent resin, the water blocking agent, of saturated with the liquid medium in sodium chloride Or sanitary thin paper characterized by being potassium chloride . Wherein the first sheet material and the second sheet material, sanitary thin paper according to claim 1, characterized in that embossing is applied. A method for producing sanitary thin paper for producing the sanitary thin paper according to claim 1,
Water, polyols, and the liquid medium containing the water blocking agent that prevents the absorption of moisture superabsorbent polymer, by dispersing super absorbent resin, and the resin dispersion preparing step of preparing a resin dispersion,
An application step of applying the resin dispersion prepared in the resin dispersion preparation step to one surface of the first sheet material and / or the second sheet material;
A bonding step in which the first sheet material and the second sheet material to which the resin dispersion is applied by the application step are bonded together with the application surface of the resin dispersion as an inner surface;
A method for producing sanitary thin paper, comprising:

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