JP3450691B2 - Liquid absorbing / releasing sheet and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an object to release a sheet intended to absorb a liquid, such as a water or oil wiping sheet, or a liquid held in the sheet to the outside. The present invention relates to a liquid absorbing / releasing sheet useful as a sheet, for example, a cleaning sheet impregnated with a cleaning agent, and more particularly to a liquid absorbing / releasing sheet having improved liquid retention.

[0002]

2. Description of the Related Art When designing a liquid absorbing / releasing sheet for the purpose of absorbing and retaining a liquid or releasing the retained liquid to the outside, the liquid absorbing / releasing sheet is designed according to its intended use. It is important to set the absorption amount and the discharge amount of the liquid, and it is particularly required to increase the amount.
In order to increase the amount of absorption and release, it is important to increase the liquid holding capacity of the sheet. As one of means for increasing the liquid holding capacity, there is a means for increasing the space for holding the liquid in the sheet. It is possible to increase the space in the sheet by decreasing the density of the sheet or increasing the thickness of the sheet. Examples of the sheet having a low density include fiber aggregates such as non-woven fabrics and foams,
The space can be increased by increasing their thickness. However, the above sheet does not have the function of absorbing or releasing liquid. Therefore, the sheet
In order to form an absorbent sheet having a high liquid retaining property, it is necessary to dispose a sheet having a liquid absorbing function on the outer surface of the sheet.

Further, as a physical property required for a sheet having a high liquid holding capacity, when the sheet is handled by hand or the like, it is necessary to have a shape-retaining property for maintaining a space against the pressure to some extent even if pressure is applied in the thickness direction. Is. For example, if the sheet is deformed and easily crushed when it is lightly pressed with a hand, the space for absorbing and holding the liquid is reduced and the absorption amount is reduced. In addition, when the liquid held inside the sheet is discharged to the outside, a large amount of the liquid is discharged, and it becomes difficult to control the degree of discharge of the liquid. On the other hand, if the sheet is too shape-retaining, the sheet becomes too hard, and the sheet is sufficiently in contact with the surface that absorbs or releases the liquid, so that the sheet loses bendability.

Air-laid nonwoven fabrics and the like are excellent as bulky nonwoven fabrics having a low density and an increased thickness. However, with respect to the compression characteristics, this airlaid nonwoven fabric is difficult to be crushed by a light pressing with a hand, but is significantly crushed when a strong force is applied, and sufficient shape retention cannot be obtained. Further, this airlaid nonwoven fabric has a slow production speed and is inferior in productivity, resulting in high cost. Further, when this airlaid nonwoven fabric is stored in a roll form, it has a drawback that it is crushed in the thickness direction due to the pressure of winding and the bulkiness is lowered, and the space for holding the liquid is reduced.

Foams such as urethane foam are known as bulky materials other than nonwoven fabrics. The foam has an advantage that it has excellent compression elasticity and does not easily collapse even when stored in a roll form. However, since urethane foam does not have a heat-sealing property, an adhesive such as hot melt must be used when a sheet having a liquid absorbing / releasing function is arranged on the outer surface thereof. Furthermore, since the production cost of urethane foam is higher than that of the nonwoven fabric and it is bulky, the diameter of the urethane foam becomes too large and the handling becomes inconvenient when it is made into a long roll.

Accordingly, it is an object of the present invention to provide a liquid absorbing / releasing sheet having good bulkiness and compression characteristics and having a large liquid absorption / holding capacity.

[0007]

Means for Solving the Problems As a result of intensive investigations by the present inventors, it has been possible to bond a specific outer layer sheet to both surfaces of an inner layer sheet having a specific compression characteristic and a specific basis weight and retain a liquid. It has been found that the above object can be achieved by a liquid absorbing / releasing sheet provided with possible space portions.

The present invention has been made on the basis of the above findings, and a liquid containing the same or different fiber aggregates is formed on both sides of an inner layer sheet made of a fiber aggregate having a large number of regularly arranged irregularities. A liquid absorbing / releasing sheet comprising: absorptive outer layer sheets attached to each other, and a space portion capable of holding a liquid formed by the irregularities is provided between the inner layer sheet and the outer layer sheet, The inner layer sheet has a thickness without load of 1 to 3 mm, a thickness under load of 5 g / cm ² is 90% or more of the thickness under load, and 30 g.
/ Cm ² The thickness under load is 50% or more of the thickness under no load, and the basis weight is 30 to 100 g / m ^2, which is formed from a fiber aggregate of thermoplastic fibers, and the outer layer sheet
The hydrophilic fibers and the fibers that can be bonded by heat treatment.
Suction heat-bonded non-woven fabric containing underfiber
Is a spunlace non-woven fabric or polyolefin fiber
It is obtained by achieving the above objects by providing a liquid absorption and release sheet, characterized in Rukoto such from Rutoburon nonwoven.

Further, according to the present invention, as a preferred method for producing the liquid absorbing / releasing sheet, a sheet made of a fiber assembly is heat-embossed by using a double-sided engraved concavo-convex roll to form a large number of regularly arranged sheets. To form an inner layer sheet on which the uneven portions are formed, and to bond both sides of the inner layer sheet with outer layer sheets made of the same or different fiber aggregates, respectively, to form a liquid layer between the inner layer sheet and the outer layer sheet. It is intended to provide a method for manufacturing a liquid absorbing / releasing sheet, which is characterized by providing a space portion capable of holding.

[0010]

Preferred embodiments of the liquid absorbing / releasing sheet of the present invention will be described below with reference to the drawings. Here, FIG. 1 is a partially cutaway perspective view showing an embodiment of the liquid absorbing / releasing sheet of the present invention, and FIG.
It is sectional drawing which follows the I line.

Liquid absorbing / releasing sheet 1 shown in FIGS. 1 and 2.
Is composed of an inner layer sheet 2 and outer layer sheets 3 and 3'which are attached to both surfaces of the inner layer sheet 2, respectively.

The inner layer sheet 2 is composed of a fiber aggregate and is subjected to heat embossing roll processing using a double-sided engraved concavo-convex roll, and a large number of regularly arranged convex portions 4 and concave portions 5 are formed on the entire surface thereof. Are formed alternately. The convex portion 4 has a substantially frustoconical shape, while the concave portion 5
Has a substantially inverted truncated cone shape corresponding to the shape of the convex portion 4.

The fibers used in the fiber assembly constituting the inner layer sheet 2 include polyolefin fibers such as polyethylene and polypropylene, polyethylene fibers such as polyethylene terephthalate, and thermoplastic fibers such as polyamide fibers such as nylon. Examples thereof include a mixture of plastic fibers and a mixture of these thermoplastic fibers and non-plastic fibers. Further, composite fibers such as core-sheath type fibers and side-by-side type fibers containing these substances as components can also be used.

A non-woven fabric is preferably used as the fiber assembly constituting the inner layer sheet 2. The type is not particularly limited, and thermal bond nonwoven fabric (for example, air through nonwoven fabric, airlaid nonwoven fabric, heat roll bond nonwoven fabric), chemical bond nonwoven fabric, needle punched nonwoven fabric,
Spunlace nonwoven fabric, meltblown nonwoven fabric, spunbond nonwoven fabric, etc. can be used.

The inner layer sheet 2 on which the convex portions 4 and the concave portions 5 are formed has compression characteristics such that the thickness under the following loads falls within the following range.

That is, the thickness of the inner layer sheet 2 is 1 under no load.
Is about 3 mm, preferably 1.5 to 2.8 mm. If the thickness under no load is less than 1 mm, the liquid holding capacity becomes small, and if it exceeds 3 mm, engraving in the depth direction using a double-sided engraving concavo-convex roll becomes difficult. In the present specification, “under no load” means under a load of 0.5 g / cm ² .

Further, the thickness of the inner layer sheet 2 under a load of 5 g / cm ² is 90% or more, and particularly preferably 95 to 100% of the thickness under no load. The thickness under a load of 5 g / cm ² corresponds to the thickness when the liquid absorbing / releasing sheet of the present invention is lightly pressed, and this thickness is 9% of the thickness under no load.
If it is less than 0%, when it is used as a liquid absorbing / releasing sheet by bonding with the outer layer sheets 3 and 3 ', the liquid absorbed and the liquid retained inside the sheet can be easily and all at once released by pressing lightly. I will end up.

Further, the thickness of the inner layer sheet 2 under a load of 30 g / cm ² is 50% or more, and particularly preferably 90% or more of the thickness under no load. The thickness under a load of 30 g / cm ² corresponds approximately to the thickness when the liquid absorbing / releasing sheet of the present invention is used with force, and this thickness is 50% of the thickness under no load. If it does not satisfy the above condition, the compressive elasticity is lowered, the recoverability to the thickness under no load is deteriorated, the recovery of the sheet thickness is small, and the space for holding the liquid becomes small.

The inner layer sheet 2 has the above-mentioned compression characteristics and has a basis weight in the range of 30 to 100 g / m ² . That is, in the liquid absorbing / releasing sheet of the present invention,
Good compression characteristics can be exhibited at a low basis weight. More specifically, if the basis weight is less than 30 g / m ² , the thickness will be crushed without exhibiting the above compression characteristics even when the uneven portion is formed on the inner layer sheet 2, and 100 g / m ²
When it exceeds m ² , the texture of the liquid absorbing / releasing sheet itself becomes too hard, and the liquid absorbing / releasing sheet is sufficiently in contact with the surface for absorbing / releasing the liquid, so that the bending property is lost. The basis weight is preferably 40 to 60 g / m ² .

The convex portions 4 and the concave portions 5 formed on the inner layer sheet 2 are uniformly and regularly present on the entire surface of the inner layer sheet 2. The diameter of the top of the convex portion 4 and the bottom of the concave portion is 1 to
It is preferably 5 mm, and the repeating pitch of the convex portions 4 and the concave portions 5 is preferably 5 to 10 mm. Further, the larger the inclination connecting the adjacent tops and bottoms of the recesses, the closer to parallel to the thickness direction of the sheet, and the stronger the pressure applied in the thickness direction. Is 0.1 to 2 when the interval [= the length L of the inclined part (see FIG. 2)] between the adjacent tops and bottoms of the recesses is 0.1.
It is preferably mm.

As shown in FIG. 2, when the inner layer sheet 2 and the outer layer sheets 3, 3'are bonded together, the convex portions 4 and the concave portions 5 are formed.
And a large number of spaces 6, 6, between the outer layer sheet 3 and 3 '.
.. is formed, and the liquid absorbed through the outer layer sheets 3, 3 ′ can be retained by this space.

Next, 'when described, the outer layer sheet 3, 3' exterior sheet 3, 3 that have the ability to absorb liquid. For example, when the liquid absorbing / releasing sheet of the present invention is used as a water-wiping sheet, a sheet made of a hydrophilic fiber aggregate is used because of its liquid nature. When used as an oil wiping sheet, a sheet made of a lipophilic (hydrophobic) fiber aggregate is used. When used by absorbing and holding a liquid containing a surfactant or the like such as a detergent, a sheet made of a hydrophilic or hydrophobic fiber aggregate may be properly used as long as the fiber is wet. Absent. The two outer layer sheets 3 and 3'may be the same or different.

When the outer layer sheets 3, 3 ′ are made of hydrophilic fiber aggregates, the hydrophilic fiber or the hydrophilic fiber aggregate is used as the fiber aggregate .
And a binder containing binder fibers that can be bonded by heat treatment.
For ction heat bond nonwovens and spunlace nonwovens
Can be Examples of hydrophilic fibers include cotton and pal
, Hemp, rayon, polyolefin fiber and polyester
Corona treatment or surface hydrophilizing agent for hydrophobic fibers such as
Those subjected to the hydrophilic treatment are preferably used. preferable
Examples include rayon fibers. binder
Considering the thermal adhesiveness with the inner layer sheet 2 for the fiber (thermal adhesive fiber)
It is mixed with consideration .

On the other hand, when the outer layer sheets 3 and 3'are made of lipophilic (hydrophobic) fiber aggregates, a melt-blown nonwoven fabric of polyolefin fibers is used as the fiber aggregates .
Can be In the case of hydrophobic fibers, the liquid absorbency is largely due to the fiber capillary phenomenon, so it is better to reduce the fiber diameter in order to increase the capillary force. For example, if the fiber diameter is 10 μm or less, especially 5 μm or less. Polyolefin fiber
Is preferably used. The basis weight of the outer layer sheet may be such that, when the outer layer sheet is laminated with the inner layer sheet to form a liquid absorbing / releasing sheet, a strength sufficient to withstand use for each application is developed, and generally 10 to 10. It is about 50 g / m ² .

The means for laminating the inner layer sheet 2 and the outer layer sheets 3, 3'is not particularly limited, and for example, adhesion by heat embossing roll, adhesion by ultrasonic roll, adhesion by using hot melt adhesive, etc. are used. It is possible,
Particularly, from the viewpoint of production speed and cost, it is preferable to bond the entire surface of the inner layer sheet 2 and the outer layer sheets 3 and 3'by heat embossing as shown in FIG.

In the heat embossing roll processing of the inner layer sheet 2 and the outer layer sheets 3, 3'in the liquid absorbing / releasing sheet 1 shown in FIG. 1, the shape of the embossing pattern is not particularly limited. However, since it is possible to reduce the liquid holding space due to the reduction in thickness due to the embossed portion, the area for performing heat embossing roll processing was reduced within a range in which the bonding strength between the outer layer sheet and the inner layer sheet was sufficient for the intended use. Better In the liquid absorbing / releasing sheet shown in FIG. 1, the embossing pattern 7 of the heat embossing roll has a continuous rhombic shape having a certain area in order to prevent the uneven portion of the inner layer sheet 2 from being broken. It has been subjected. It is desirable that the lengths of the long diagonal line and the short diagonal line of this diamond are 40 to 80 mm and 20 to 60 mm, respectively. Further, the width W (see FIG. 1) of the embossed pattern 7 is 0.5 in order that the bonding strength between the inner layer sheet and the outer layer sheet is sufficient for the intended use and a wider internal space for retaining the liquid is secured. It is preferably ˜2 mm. In FIG. 1, only the upper outer layer sheet 3 is provided with the embossed pattern 7, but in the present embodiment, the lower outer layer sheet 3'is also similarly provided with the embossed pattern.

When the inner layer sheet 2 and the outer layer sheets 3 and 3'are attached to each other by heat embossing roll processing to form the liquid absorbing / releasing sheet 1, the embossed area ratio is 5 of the total area of the liquid absorbing / releasing sheet 1. -30% is preferable, and 10-20% is more preferable.

The total basis weight of the liquid absorbing / releasing sheet 1 is
In order to fully develop its function, 40-150 g /
is preferably m ^2, and further preferably 50~110g / m ^2. Further, the liquid absorbing / releasing sheet 1 is
The liquid holding capacity is preferably 1200 to 2000 g / m ² . The method for measuring the liquid holding capacity will be described in detail in Examples described later.

Next, a preferred method for manufacturing the liquid absorbing / releasing sheet 1 of this embodiment will be described with reference to FIG. Here, FIG. 3 is a schematic view showing an apparatus preferably used for manufacturing the liquid absorbing / releasing sheet 1 of the present embodiment.

In the apparatus 10 shown in FIG. 3, first, a sheet 12 made of a fiber assembly as a raw material constituting the inner layer sheet 2 is unwound from a roll 12a, and a space between a pair of double-sided engraved concavo-convex rolls 13 and 13 'is provided. Is inserted into. Each of the double-sided engraved concavo-convex rolls 13 and 13 'has engraved patterns of irregularities arranged regularly on its surface, and the concavities and convexities mesh with each other when both rolls in the direction of the arrow in FIG. It is done like this. By inserting the sheet 12 between the rolls meshed with each other,
The sheet 12 is formed with the convex portions 4 and the concave portions 5 corresponding to the above-mentioned concave and convex pattern to form the inner layer sheet 2. In this case, either or both of the double-sided engraved concavo-convex rolls 13 and 13 'may be heated depending on the material of the fibers forming the sheet 12. The heating temperature depends on the material of the fibers forming the sheet 12, but is generally 100 to 150.
The temperature is preferably set to ° C. Also, double-sided engraving roll 1
The pressure between 3 and 13 'may be in a range sufficient to form irregularities on the sheet 12.

Subsequently, the outer layer sheets 3 and 3'are attached to both surfaces of the obtained inner layer sheet 2 by an in-line operation. The outer layer sheets 3 and 3 ′ are unwound from the rolls 3a and 3a ′, guided by the guide rolls 14 and 14 ′, and at the positions of the embossing rolls 15 and 15 ′, the inner layer sheet 2 is formed.
When these three meet, they emboss rolls 15 and 15 '
Inserted in between. Of the embossing rolls 15 and 15 ',
The upper roll 15 is an engraving roll engraved with a predetermined pattern, and the lower roll 15 'is a smooth roll. By heat embossing roll processing with the embossing rolls 15 and 15 ′, the outer layer sheets 3 and 3 ′ are bonded to the inner layer sheet 2, and the three are integrated. Then, between the outer layer sheets 3 and 3 ′ and the inner layer sheet 2, there is provided a space formed by the convex portion 4 and the concave portion 5 capable of holding the liquid. In this heat embossing roll processing, the temperature of the embossing rolls 15 and 15 'is generally 100.
It is about 150 ° C. The embossing rolls 15 and 1
Both of 5'may be heated, or only one of them may be heated.

Next, the liquid absorbing / releasing sheet 1 is obtained by cutting a long sheet in which the outer layer sheets 3 and 3'and the inner layer sheet 2 are integrated into a predetermined length.

When the liquid absorbing / releasing sheet 1 thus obtained is used as a cleaning sheet impregnated with a cleaning agent, a predetermined cleaning agent is impregnated by spraying or dipping in the subsequent step. .

According to this manufacturing method, the inner layer sheet 2 having the irregularities is once wound and then the outer layer sheet 3,
Compared to the off-line manufacturing method that is attached to 3 ',
Since the inner layer sheet 2 is prevented from being crushed in the thickness direction and the bulkiness of the inner layer sheet 2 is not lowered, a liquid absorbing / releasing sheet having excellent compression characteristics can be obtained. In addition, a roll of a bulky sheet has a shorter winding length than a roll of a sheet having a low bulkiness due to its bulkiness, when compared with the same roll diameter, and a winding time interval when performing high-speed processing. Since it is short, there is a drawback in that productivity is reduced by changing the scroll. On the other hand, in the above-described manufacturing method, since bulkiness is imparted to the inner layer sheet during the manufacturing process of the liquid absorbing / releasing sheet, the winding length of the unrolled raw material can be lengthened, and the winding time interval is also long. Therefore, productivity is improved.

Although the liquid absorbing / releasing sheet of the present invention has been described based on its preferred embodiment, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. is there. For example, the shape of the concavo-convex portion formed on the inner layer sheet 2 is not limited to the shape shown in FIGS. 1 and 2, and there is a space portion that can hold a liquid between the inner layer sheet 2 and the outer layer sheets 3 and 3 ′. Any shape may be used as long as it is formed and can exhibit the above-mentioned compression characteristics. Further, as will be apparent from the examples described later, it is also possible to use two or more nonwoven fabrics or the like that are superposed on each other and have irregularities formed thereon as the inner layer sheet.

The liquid absorbing / releasing sheet of the present invention can be used by itself as a wiping sheet for various liquids (for example, water and oil), or can be used for various liquids (cleaning agents, etc.).
It can be used as a cleaning sheet impregnated with. Then, as described above, by appropriately selecting the material of the fibers constituting the inner layer sheet and the outer layer sheet,
A liquid absorbing / releasing sheet most suitable for each application can be formed.

[0037]

EXAMPLES Hereinafter, the liquid absorbing / releasing sheet of the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited to such embodiments.

Prior to the Examples and Comparative Examples, the methods for measuring the compression characteristics of the inner layer sheet, the liquid retention capacity and the bendability of the liquid absorption / release sheets obtained in the Examples and Comparative Examples will be described. .

<Measurement of compression characteristic> To measure the compression characteristic of the inner layer sheet, a KES-FB test system (Kawaba) was used.
ta's Evaluation System fo
Kato Tech Co., Ltd., which is a part of r Fabrics)
A compression tester KES-FB3 (registered trademark) manufactured by the same company was used. The compression load was set in the range of 0 to 50 g / cm ² , and the thickness of the inner layer sheet was plotted. The inner layer sheet thickness under no load was the thickness under a load of 0.5 g / cm ² . The thickness of the inner layer sheet was measured with a load of 5 g / cm ² when lightly pushed by hand and a load of 30 g / cm ² when strongly pushed. The measurement value was measured at 5 points on the sheet, and the average value was taken as the thickness of the inner layer sheet.

<Measurement of liquid holding capacity> The liquid holding capacity of the liquid absorbing / releasing sheet was measured by first measuring 10 cm of the liquid absorbing / releasing sheet.
Cut into a size of 10 cm and measure the weight. Although the liquid varies depending on the intended use, the liquid absorbing / releasing sheet is soaked in the target liquid, and the upper and lower surfaces of the sheet are pressed by the hand to absorb the liquid sufficiently, and then the sheet is pulled up. And
The weight is measured when the liquid does not drop from the sheet. The weight difference before and after the absorption of the liquid was determined, and the liquid retention capacity (g / m ² ) was calculated from the following formula. As the liquid to be absorbed, tap water assuming a water-wiping sheet and salad oil [Honen Corporation S (Honen Corporation S Co., Ltd.)] assuming a oil-wiping sheet were used. Furthermore,
As a liquid to be absorbed, a dishwashing detergent that assumes a cleaning sheet [Family Fresh 1/2 made by Kao Corporation]
(Registered trademark)] was also used as a 1000-fold dilution.

[0041]

[Equation 1]

<Bendability> The following ability to the absorbing surface and the discharging surface due to the bending of the sheet when the liquid absorbing / releasing sheet was wiped by hand was evaluated. Five monitors wiped a hard surface (such as a wooden table), and then the curved surface of the table was wiped to examine the followability due to sheet bending. As a criterion, a sheet having sufficient bendability was 2 points, a sheet having a slightly hard but bendability was 1 point, and a sheet having no bendability was 0 point. 6 points were marked with Δ, and 0 to 2 points were marked with x.

[Example 1] A polypropylene spunbonded nonwoven fabric having a basis weight of 30 g / m ² [Spunbonded nonwoven fabric Syntex PS-106 (registered trademark) manufactured by Mitsui Chemicals, Inc.] was used as a double-sided engraved concavo-convex roll [Yuri]. roll Co. sided engraved uneven roll] sets the heat roll embossing machine [Yuri roll Co., steel match clearance embossed machine interior sheets with uneven embossing by (R)] (basis weight 38 g / m ²⁾ Got The compression characteristics and thickness of this inner layer sheet are shown in Table 1. Rayon fiber [Rayon fiber Corona (registered trademark) manufactured by Daiwabo Co., Ltd.] and thermal adhesive fiber [Thermal adhesive fiber NBF manufactured by Daiwabo Co., Ltd.]
(Registered trademark)] in a weight ratio of 4: 6, and spun lace nonwoven fabric (basic weight 4
0 g / m ² ), an outer layer sheet made of 0 g / m ² ) is overlaid on both sides of this inner layer sheet in-line, and heat embossing is performed on the three parts [embossing roll; rhombus embossing roll manufactured by Toyo Riken Co., Ltd., rhombus long diagonal 60 mm, short Diagonal line 4
0 mm, rhombic pattern width 1 mm and depth 1 mm, receiving roll; mirror roll] were bonded and integrated to obtain a liquid absorbing / releasing sheet shown in FIGS. 1 and 2. The basis weight of this liquid absorbing / releasing sheet was 118 g / m ² .

[Example 2] ^Two polypropylene spunbonded nonwoven fabrics having a grammage of 40 g / m ² [Spunbonded nonwoven fabric Syntex PS108 (registered trademark) manufactured by Mitsui Chemicals, Inc.] were stacked, and the same as in Example 1. Then, an inner layer sheet (basis weight: 100 g / m ² ) was produced. Furthermore, using the spunlace nonwoven fabric used in Example 1 as the outer layer sheet, Example 1
The three sides were stuck together with the diamond-shaped embossing roll used in 1. to obtain a liquid absorbing / releasing sheet. The basis weight of this liquid absorbing / releasing sheet is 1
It was 80 g / m ² .

Example 3 Using the polypropylene spunbonded nonwoven fabric used in Example 1, an inner layer sheet (basis weight: 38 g / m ² ) was produced in the same manner as in Example 1. Inline polypropylene meltblown non-woven fabric on both sides of this inner layer sheet [manufactured by Mitsui Chemicals, Inc., fiber diameter 3 μm, basis weight 1
5 g / m ² ], and the three layers were laminated with the diamond-shaped embossing roll used in Example 1 to obtain a liquid absorbing / releasing sheet. The basis weight of this liquid absorbing / releasing sheet was 68 g / m ² .

Example 4 An inner layer sheet (basis weight: 100 g / m ² ) was produced in the same manner as in Example 2 using the polypropylene spunbonded nonwoven fabric used in Example 2. An outer layer sheet made of polypropylene meltblown nonwoven fabric (manufactured by Mitsui Chemicals, Inc., fiber diameter: 3 μm, basis weight: 15 g / m ² ) was overlaid on both sides of this inner layer sheet with the rhombus heat embossing roll used in Example 1. The three members were stuck together to obtain a liquid absorbing / releasing sheet. The basis weight of this liquid absorbing / releasing sheet was 130 g / m ² .

[Comparative Example 1] A sheet having a three-layer structure was obtained in the same manner as in Example 1 except that the spunbonded nonwoven fabric of the inner layer sheet was not subjected to uneven embossing.

Comparative Example 2 A sheet having a three-layer structure was obtained in the same manner as in Example 2 except that the spunbonded nonwoven fabric of the inner layer sheet was not subjected to uneven embossing.

Comparative Example 3 A polypropylene spunbonded nonwoven fabric having a basis weight of 20 g / m ² [Spunbonded nonwoven fabric Syntex PS-104 (registered trademark) manufactured by Mitsui Chemicals, Inc.] was prepared in the same manner as in Example 1. Concavo-convex embossing was performed to produce an inner layer sheet (basis weight 26 g / m ² ). The spunlaced nonwoven fabric used in Example 1 as an outer layer sheet was superposed on both sides of this inner layer sheet, and the three members were bonded by the diamond-shaped embossing roll used in Example 1 to obtain a sheet having a three-layer structure.

[Comparative Example 4] A polypropylene spunbonded nonwoven fabric having a basis weight of 50 g / m ² [Spunbonded nonwoven fabric Syntex PS-110 (registered trademark) manufactured by Mitsui Chemicals, Inc.] was layered on two sheets. In the same manner as in Example 1, uneven embossing was applied to produce an inner layer sheet (basis weight 130 g / m 2). The spunlaced nonwoven fabric used in Example 1 as an outer layer sheet was superposed on both sides of this inner layer sheet, and the three members were bonded by the diamond-shaped embossing roll used in Example 1 to obtain a sheet having a three-layer structure.

[Comparative Example 5] A sheet having a three-layer structure was obtained in the same manner as in Example 3 except that the spunbonded nonwoven fabric of the inner layer sheet was not embossed.

Comparative Example 6 A polypropylene spunbonded nonwoven fabric having a basis weight of 20 g / m ² [Spunbonded nonwoven fabric Syntex PS-104 (registered trademark) manufactured by Mitsui Chemicals, Inc.] was prepared in the same manner as in Example 1. Concavo-convex embossing was performed to produce an inner layer sheet (basis weight 26 g / m ² ). The melt blown nonwoven fabric used in Example 3 was superposed on both surfaces of this inner layer sheet as an outer layer sheet, and the three members were bonded by the diamond-shaped embossing roll used in Example 1 to obtain a sheet having a three-layer structure.

[Comparative Example 7] A polypropylene spunbonded nonwoven fabric having a basis weight of 50 g / m ² [Spunbonded nonwoven fabric Syntex PS-110 (registered trademark), manufactured by Mitsui Chemicals, Inc.] was stacked on two sheets. In the same manner as in Example 1, uneven embossing was applied to produce an inner layer sheet (basis weight 130 g / m 2). The melt blown nonwoven fabric used in Example 3 was superposed on both surfaces of this inner layer sheet as an outer layer sheet, and the three members were bonded by the diamond-shaped embossing roll used in Example 1 to obtain a sheet having a three-layer structure.

[0054]

[Table 1]

As is clear from the results shown in Table 1, Example 1 provided with an inner layer sheet having concavo-convex portions formed by heat embossing roll processing using a double-sided engraved concavo-convex roll and having a specific compression characteristic and specific weight. The liquid absorbing / releasing sheets (invention products) of Nos. 4 to 4 exhibit sufficient shape retention of the uneven portion against compression, and can increase the liquid absorbing capacity, as compared with the sheets of Comparative Examples. It can be seen that the bendability is also sufficiently maintained. Further, since the emboss of the inner layer sheet is not crushed by a light force, a large amount of the absorbed liquid is not released at a time, and the release amount is adjusted by the liquid absorbing ability of the outer layer sheet.

[0056]

As described above in detail, according to the present invention,
A liquid absorbing / releasing sheet having good bulkiness and compression characteristics and having a large liquid absorption / holding capacity can be obtained. In particular, by forming the concavo-convex portion of the inner layer sheet with a double-sided engraving embossing roll, the bulkiness and compression characteristics are further improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a liquid absorbing / releasing sheet of the present invention.

FIG. 2 is a cross-sectional view taken along line I-I in FIG.

FIG. 3 is a schematic view showing an apparatus preferably used for manufacturing the liquid absorbing / releasing sheet 1 of the present embodiment.

[Explanation of symbols]

1 Liquid absorption / release sheet 2 Inner layer sheet 3,3 'outer layer sheet 4 convex 5 recess

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Hanaoka, 2606, Kao Co., Ltd., Kaiga-cho, Haga-gun, Tochigi Prefecture (72) Inventor, Eiichi Hoshino, 2606, Akabane, Kai-cho, Haga-gun, Tochigi, Ltd. (56) References JP-A-6-189884 (JP, A) JP-A-10-272082 (JP, A) JP-A-6-14859 (JP, A) JP-A-8-243065 (JP, A) (58) Survey Areas (Int.Cl. ⁷ , DB name) A47L 13/16

Claims (5)

(57) [Claims] 1. A liquid-absorbent outer layer sheet made of the same or different fiber aggregate is attached to both surfaces of an inner layer sheet made of a fiber aggregate in which a large number of regularly arranged irregularities are formed, A liquid absorbing / releasing sheet having a space formed between the inner layer sheet and the outer layer sheet capable of holding a liquid formed by the uneven portion, wherein the inner layer sheet has a thickness under no load. 1-3 mm, 5
The thickness under g / cm ² load is 90% or more of the thickness under no load, the thickness under 30 g / cm ² load is 50% or more of the thickness under no load, and the basis weight is 30-100g / m
² is formed from a fiber assembly of thermoplastic fibers .
Ri, the outer layer sheet, contact by a hydrophilic fibers and heat treatment
Suction heat bond containing binder fibers that can be worn
Nonwoven or spunlace nonwoven, or polyolefin
A liquid absorbing / releasing sheet, which is made of a melt-blown non-woven fabric . 2. The liquid absorbing / releasing sheet according to claim 1, wherein the uneven portion of the inner layer sheet is formed by heat embossing roll processing using a double-sided engraving uneven roll. 3. The liquid absorbing / releasing sheet according to claim 1, wherein the inner layer sheet and the outer layer sheet are laminated by heat embossing. 4. A liquid holding capacity of 1200 to 2000 g /
It is m ^2, and liquid absorption and release sheet according to any one of claims 1-3. 5. The method for producing a liquid absorbing / releasing sheet according to claim 1, wherein the sheet made of the fiber assembly is heat-embossed using a double-sided engraved concavo-convex roll and arranged regularly. An inner layer sheet having a large number of concavo-convex portions is formed, and outer layer sheets made of the same or different fiber aggregates are attached to both surfaces of the inner layer sheet, respectively, and a liquid is applied between the inner layer sheet and the outer layer sheet. A method of manufacturing a liquid absorbing / releasing sheet, characterized in that a space portion capable of holding the liquid is provided.