WO2011108375A1

WO2011108375A1 - Sheet having water impermeability and water disintegrability

Info

Publication number: WO2011108375A1
Application number: PCT/JP2011/053600
Authority: WO
Inventors: 孝義小西; 水谷　聡
Original assignee: ユニ・チャーム株式会社
Priority date: 2010-03-05
Filing date: 2011-02-15
Publication date: 2011-09-09
Also published as: JP5582828B2; JP2011183613A

Abstract

Provided is a sheet having water impermeability and water disintegrability. Specifically, provided is a water-impermeable and water-disintegrable sheet containing a hydrophobic fine particle layer (A), a water-soluble resin layer (B), and a biodegradable non-aqueous layer (C), wherein: the water-soluble resin layer (B) is disposed between the hydrophobic fine particle layer (A) and the biodegradable non-aqueous layer (C), and is adhered to the biodegradable non-aqueous layer (C); the hydrophobic fine particle layer (A) has a water contact angle of over 90° as a consequence of the surface of the hydrophobic fine particle layer (A) on the opposite side of the non-aqueous resin layer (B) being provided with a finely irregular structure formed by laminating hydrophobic fine particles, and is a layer that disintegrates when subjected to water flow; and the biodegradable non-aqueous layer (C) is water insoluble, and is a layer that divides at least into two pieces when the water-soluble resin layer (B) dissolves in water.

Description

Impermeable and water-degradable sheet

The present invention relates to a water-impermeable and water-decomposable sheet comprising a hydrophobic fine particle layer (A), a water-soluble resin layer (B), and a biodegradable water-insoluble layer (C).

Absorbent articles such as sanitary napkins, vaginal absorbent pads, incontinence pads, etc. contain materials that are not water-degradable. After use, dispose of them in a storage box installed in the toilet and collect them. Need to be disposed of. However, if the used absorbent article is accidentally poured into a flush toilet when discarded, the piping of the flush toilet may be clogged. Accordingly, studies have been conducted on absorbent articles made of water-degradable materials that can be used as they are in a flush toilet after use.

Patent Document 1 includes a water-soluble waterproofing film comprising a water-soluble polyvinyl alcohol (hereinafter sometimes referred to as “PVA”) film and a biodegradable waterproof layer laminated on at least one surface of the PVA film. A film is disclosed in which the biodegradable waterproof layer contains a shellac resin derivative and a curing agent.

However, the water-soluble waterproof film described in Patent Document 1 has water impermeability on the biodegradable waterproof layer side containing shellac resin, but the water-soluble PVA film layer side does not have water impermeability. Accordingly, when the PVA film layer side is touched with a wet hand, or when sweat or the like enters the PVA film layer side, a problem may occur in water impermeability.

Furthermore, in Patent Document 1, in [0058], a mode of a water-soluble waterproof film in which a biodegradable waterproof layer is laminated on both sides of a PVA film layer to improve water impermeability is mentioned. When the person conducted an experiment (Comparative Example 2 to be described later), it was found that this aspect is excellent in water impermeability, but water disintegration is significantly reduced.
In addition, since water-soluble PVA film has high hygroscopicity, the water-soluble waterproof film from which the PVA film is exposed may cause curling, stickiness, etc. unless the humidity is sufficiently controlled, and productivity is increased. It may decrease.

JP2004-142426

As described above, the water-soluble waterproof film described in Patent Document 1 did not have water decomposability and water impermeability.
Accordingly, an object of the present invention is to provide a sheet having water impermeability and water decomposability.

As a result of intensive investigations to solve the above problems, the present inventors have found that a hydrophobic fine particle layer (A), a water-soluble resin layer (B), and a biodegradable water-insoluble layer (C) are included. A sheet having water permeability and water decomposability, wherein the water-soluble resin layer (B) is between the hydrophobic fine particle layer (A) and the biodegradable water-insoluble layer (C) and is biodegradable water-insoluble. The hydrophobic fine particle layer (A) is adhered to the layer (C), and the hydrophobic fine particles are laminated on the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B). It is a layer having a water contact angle of more than 90 ° by having a fine concavo-convex structure formed, and collapsing by being swallowed by a water stream, and the biodegradable water-insoluble layer (C) is water-insoluble It is a layer that is divided into at least two pieces as the water-soluble resin layer (B) dissolves in water. The sheet according to claim, can solve the above problems, and have completed the present invention.

Specifically, the present invention relates to the following aspects.
[Aspect 1]
A sheet having water impermeability and water decomposability, comprising a hydrophobic fine particle layer (A), a water-soluble resin layer (B), and a biodegradable water-insoluble layer (C),
The water-soluble resin layer (B) is between the hydrophobic fine particle layer (A) and the biodegradable water-insoluble layer (C) and adhered to the biodegradable water-insoluble layer (C),
The hydrophobic fine particle layer (A) has a fine uneven structure formed by laminating hydrophobic fine particles on the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B). And a biodegradable water-insoluble layer (C) is a water-insoluble and water-soluble resin layer (B) having a water contact angle of more than 90 ° and disintegrating by being swallowed by a water stream. ) Is dissolved in water and is divided into at least two pieces.
A sheet characterized by that.

[Aspect 2]
The sheet according to aspect 1, wherein the hydrophobic fine particles include inorganic fine particles.
[Aspect 3]
The sheet according to embodiment 1 or 2, wherein the hydrophobic fine particles have an average particle diameter of 1 to 100 nm.

[Aspect 4]
The sheet according to any one of aspects 1 to 3, wherein the hydrophobic fine particle layer (A) has a basis weight of 0.1 to 3 g / m ² .
[Aspect 5]
The sheet according to any one of aspects 1 to 4, further comprising a water-decomposable substrate layer (D) between the hydrophobic fine particle layer (A) and the water-soluble resin layer (B).

[Aspect 6]
The sheet according to aspect 5, wherein the water-decomposable substrate layer (D) comprises a material selected from the group consisting of hydrolyzed paper and hydrolyzable nonwoven fabric.
[Aspect 7]
The biodegradable water-insoluble layer (C) comprises a material selected from the group consisting of shellac, polylactic acid, polycaprolactone, beeswax, paraffin wax, carnauba wax, rice wax, chitin, hydrophobic starch and polybutylene succinate; The sheet according to any one of aspects 1 to 6.

[Aspect 8]
The water-soluble resin layer (B) is selected from the group consisting of water-soluble urethane, polyvinyl alcohol polymer, polyacrylamide, polyacrylic acid polymer, polyethylene oxide, vinyl ether polymer, sulfo-modified polyester, polyurethane derivative and polysaccharide. The sheet according to any one of aspects 1 to 7, comprising a material.
[Aspect 9]
The sheet according to any one of aspects 1 to 8, wherein the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B) has a water pressure resistance of 30 to 300 mm.

[Aspect 10]
The sheet according to any one of aspects 1 to 9, wherein the surface of the biodegradable water-insoluble layer (C) opposite to the water-soluble resin layer (B) has a water pressure resistance of 400 mm or more.
[Aspect 11]
The sheet according to any one of aspects 1 to 10, wherein the dispersion rate (%) after the shake flask test is 50% by mass or more.

[Aspect 12]
The sheet according to any one of aspects 1 to 11, further comprising a water-soluble resin layer (B) as an additional layer on the biodegradable water-insoluble layer (C).
[Aspect 13]
Providing a water-soluble resin layer (B);
Laminating the hydrophobic fine particle layer (A) on the water-soluble resin layer (B); and laminating the biodegradable water-insoluble layer (C) on the water-soluble resin layer (B):
The manufacturing method of the sheet | seat of aspect 1 containing this.

[Aspect 14]
Laminating the water-soluble resin layer (B) on the water-decomposable substrate layer (D);
Laminating the hydrophobic fine particle layer (A) on the water-degradable substrate layer (D); and laminating the biodegradable water-insoluble layer (C) on the water-soluble resin layer (B):
The manufacturing method of the sheet | seat of aspect 5 containing this.

The sheet having water impermeability and water decomposability of the present invention has a hydrophobic fine particle layer (A) having a predetermined impermeability on one side and a predetermined impermeability on the other side. Since it has the biodegradable water-insoluble layer (C) it has, it has water impermeability at the time of use.
Further, when the sheet having water impermeability and water decomposability of the present invention is rubbed in water, the fine irregular structure of the hydrophobic fine particles of the hydrophobic fine particle layer (A) collapses to lose water impermeability, Since the remaining layers are water soluble or can be hydrolyzed, they are water decomposable after disposal in water.

FIG. 1 is a schematic cross-sectional view of one embodiment of a sheet having water impermeability and water decomposability according to the present invention.
FIG. 2 is a schematic view of a cross section of another embodiment of the sheet having water impermeability and water decomposability of the present invention.

Hereinafter, the sheet having water impermeability and water decomposability of the present invention will be described in detail.
[Hydrophobic fine particle layer (A)]
The hydrophobic fine particle layer (A) has a fine uneven structure formed by laminating hydrophobic fine particles on the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B). , A layer having a water contact angle of more than 90 ° and collapsing by being swallowed by a water stream. The hydrophobic fine particle layer (A) exhibits water impermeability when used in the sheet having water impermeability and water decomposability of the present invention, and becomes a starting point of water disintegration after disposal. The hydrophobic fine particle layer (A) can also reduce curling and stickiness due to moisture absorption of the water-soluble resin layer (B).
Since the hydrophobic fine particles adhere to the water-soluble resin layer (B), the water-degradable base material layer (D), etc. by van der Waals force, the hydrophobic fine particle layer (A) is swollen with a water flow after disposal. It collapses easily.

In the present specification, the “hydrophobic fine particle” means that the hydrophobic fine particle layer (A) having a fine concavo-convex structure formed by laminating the hydrophobic fine particles satisfies the water repellency requirement described later. Means fine particles.
The hydrophobic fine particles are not particularly limited, and for example, inorganic fine particles, for example, titanium oxide, zinc oxide, barium sulfate, boron nitride, SnO ₂ , silica, Cr ₂ O ₃ , Al ₂ O ₃ , Fe ₂ O. ₃ , SiC, cerium oxide and the like. As for the hydrophobic fine particles, the surface characteristics such as polarity are particularly important, and surface treatment and surface modification are performed as necessary so that the hydrophobic fine particle layer (A) satisfies the requirements for water repellency described later. Etc. may be applied.

As the hydrophobic fine particles that can be used in the present invention, silica, titanium oxide, and zinc oxide are particularly preferable from the viewpoint of safety. Examples of the commercially available hydrophobic fine particles include Adesso WR series manufactured by Nikka Chemical Co., Ltd.

The hydrophobic fine particle layer (A) having a fine concavo-convex structure has a larger contact angle of a liquid, for example, water than that having a flat surface. The reason is as follows.
When the contact angle of the liquid is θ and the contact angle of the liquid when the surface area of the material is increased r times in a specific substrate having a flat surface is θ _r , the following equation (1):
cos θ _r = _r cos θ (1)
Is established.
In Equation (1), since 1 <r, when 90 ° <θ, θr increases as _r increases, that is, the contact angle of the liquid increases.
When θ <90 °, the larger _r is, the smaller _θr is, that is, the liquid contact angle is smaller.

As described above, the hydrophobic fine particle layer (A) having a fine concavo-convex structure has an r value larger than 1, so that the contact angle of a liquid, for example, water is larger than that having a flat structure.
Examples of the fine concavo-convex structure having a larger r value include a fractal structure, for example, a fine protrusion-like fractal structure.
In the present specification, “liquid” includes a solution containing water, for example, body fluid, for example, menstrual blood, and excrement, for example, urine.

The water repellency of the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B) can be evaluated by a water contact angle. The water contact angle of the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B) is more than about 90 °, preferably about 120 ° or more, and about 140 ° or more. More preferably, it is more preferably about 160 ° or more. This is because the larger the water contact angle is, the more difficult it is for the liquid to penetrate into the hydrophobic fine particle layer (A), thereby leading to less leakage of the sheet of the present invention.
The water contact angle can be measured by, for example, an automatic contact angle meter CA-V type manufactured by Kyowa Interface Science Co., Ltd.

The surface of the hydrophobic fine particle layer (A) on the side opposite to the water-soluble resin layer (B) preferably has a certain water resistance according to the intended use. The water resistance can be evaluated by water pressure resistance. The range of the water pressure resistance varies depending on the application to be used. Generally, the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B) is about 30 to about 300 mm. The water pressure is preferably about 50 to about 250 mm, and more preferably about 50 to about 200 mm. If the water pressure is less than about 30 mm, leakage may occur when pressure is applied due to body pressure, etc., and if the water pressure exceeds about 300 mm, the water pressure will be hydrophobic due to the water pressure when flushed to a flush toilet. In some cases, the fine particle layer (A) is not easily disintegrated, and the sheet having water-imperviousness and water-decomposability of the present invention is difficult to hydrolyze.
In addition, the water pressure used in this specification can be measured according to JIS L 1092 water resistance test A method (low water pressure method).

The average particle size of the hydrophobic fine particles is not particularly limited as long as it is within the range where the effects of the present invention are exerted, but is preferably about 1 nm to about 100 nm, more preferably about 10 nm to about 80 nm, and More preferably, it is about 20 nm to about 60 nm. By using the hydrophobic fine particles having the above average particle diameter, aggregation can be prevented and dispersion stability can be improved. On the other hand, if the average particle size is less than about 1 nm, the production cost tends to increase, the thickness of the hydrophobic fine particle layer (A) tends to decrease, and water repellency tends to be difficult to ensure. Furthermore, when the average particle diameter exceeds about 100 nm, gaps are easily formed between the particles, it is difficult to ensure water repellency, hydrophobic fine particles are easily detached from the base material, and the tactile sensation during wearing tends to be hard. There is a tendency to become.
In the present specification, the “average particle diameter” is obtained by randomly picking up about 300 particles from an image taken with an electron microscope, measuring their particle diameters, and arithmetically averaging them. Value.

In the water-impermeable and water-decomposable sheet of the present invention, the hydrophobic fine particle layer (A) preferably has a basis weight of about 0.1 to about 3 g / m ² and about 0.1 to about 2 g. It is more preferable to have a basis weight of / m ² or less. When the basis weight is less than about 0.1 g / m ² , unevenness of the hydrophobic fine particles occurs, and a place where water repellency cannot be obtained may occur. If the basis weight exceeds about 3 g / m ² , it tends to be economically disadvantageous.
The thickness of the hydrophobic fine particle layer (A) is preferably about 1 μm or less.

[Water-soluble resin layer (B)]
The water-soluble resin layer (B) is a layer containing a water-soluble resin, and is adhered to the biodegradable water-insoluble layer (C). The water-soluble resin layer (B) is used to disintegrate the hydrophobic fine particle layer (A) and to be optionally water-decomposable when the water-impermeable and water-decomposable sheet of the present invention is discarded in a large amount of water such as a toilet. It dissolves in water following the hydrolysis of the base material layer (D), and has a role of assisting the adjacent biodegradable water-insoluble layer (C) to be divided into at least two pieces. Moreover, when the sheet | seat which has the water-impermeable property of this invention and water decomposability has a water-decomposable base material layer (D), a water-soluble resin layer (B) is a stop of water-degradable base material (D). Can also have a role.

It is preferable that the water-soluble resin layer (B) has water solubility such that it is dissolved in water by being swollen with a water stream at room temperature, for example, 25 ° C.
Adhesion between the water-soluble resin layer (B) and the biodegradable water-insoluble layer (C) may be performed using an adhesive, or without using an adhesive, the water-soluble resin layer (B ) And / or the biodegradable water-insoluble layer (C) itself may be adhered to each other.

The water-soluble resin layer (B) is not particularly limited as long as the water-soluble resin layer (B) is formed from the material having the above characteristics. Examples of the material constituting the water-soluble resin layer (B) include water-soluble urethane and polyvinyl alcohol polymers, such as , Polyvinyl alcohol and modified products thereof, polyacrylamide, polyacrylic acid polymers such as polyacrylic acid and acrylic acid-containing acrylic polymers, polyethylene oxide, vinyl ether polymers, sulfo-modified polyesters, polyurethane derivatives, and polysaccharides such as Carboxymethylcellulose salts and alginates are mentioned.

In the water-impermeable and water-decomposable sheet of the present invention, the water-soluble resin layer (B) preferably has a basis weight of about 10 to about 40 g / m ² and about 15 to about 30 g / m ² or less. It is more preferable to have a basis weight of If the basis weight is less than about 10 g / m ² , the biodegradable water-insoluble layer (C) may not be divided into at least two pieces, and the water-decomposable substrate (D) may not be sealed. It may be insufficient. When the basis weight exceeds about 40 g / m ² , the sheet becomes hard and the tactile sensation is deteriorated, and it takes time for the sheet having water impermeability and water decomposability of the present invention to be hydrolyzed and clogs the sewer pipe. There is a case.

[Biodegradable water-insoluble layer (C)]
The biodegradable water-insoluble layer (C) is a layer that is water-insoluble and is divided into at least two pieces as the water-soluble resin layer (B) is dissolved in water. The biodegradable water-insoluble layer (C) exhibits the water-impermeable nature of the biodegradable water-insoluble layer (C) side in use in the sheet having water-impermeable and water-degradable properties of the present invention, and is discarded into water. Later, as the water-soluble resin layer (B) is dissolved, it is divided into at least two pieces, preferably into small pieces.

Since the biodegradable water-insoluble layer (C) should be divided into at least two pieces as the water-soluble resin layer (B) is dissolved, it is preferably not crosslinked.
The water-insoluble is preferably one that does not dissolve in the liquid upon contact with the liquid during use.

The biodegradable water-insoluble layer (C) preferably has high water pressure resistance. Specifically, the surface of the biodegradable water-insoluble layer (C) opposite to the water-soluble resin layer (B) is about It preferably has a water pressure resistance of 400 mm or more, preferably has a water pressure resistance of about 600 mm or more, and most preferably has a water pressure resistance of about 1000 mm or more. If the water pressure resistance is less than about 400 mm, leakage may occur when body pressure or the like is applied during use. As long as the biodegradable water-insoluble layer (C) has performance such as biodegradability, there is no particular upper limit to the value of the water pressure resistance.

The water pressure resistance of the biodegradable water-insoluble layer (C) varies depending on the product to be used. In the case of a panty liner, the water pressure pressure is preferably about 400 mm or more, and in the case of a sanitary napkin, Is preferably about 800 mm or more, and in the case of paper diapers, the water pressure resistance is preferably about 1000 mm or more.
The water pressure resistance on the biodegradable water-insoluble layer (C) side can be controlled by the composition of the biodegradable water-insoluble layer (C), the thickness of the layer, and the like.

In addition, the biodegradable water-insoluble layer (C) preferably has a low moisture permeability, and specifically has a moisture permeability of about 50 g / m ² · 24 Hr or less. This is because when the moisture permeates, the water-soluble resin layer (B) therein dissolves and the biodegradable water-insoluble layer (C) may not be able to maintain the water pressure resistance.
The moisture permeability can be measured according to a moisture permeability test method for JIS Z 0208 moisture-proof packaging material.

In addition, from the same viewpoint as the moisture permeability, the biodegradable water-insoluble layer (C) preferably has low air permeability. Specifically, measurement is performed using a tester KES F8-AP1 manufactured by Kato Tech Co., Ltd. The measured ventilation resistance value preferably has a size exceeding the measurement range.

The biodegradable water-insoluble layer (C) is not particularly limited as long as it has the above-mentioned properties. For example, shellac, polylactic acid, polycaprolactone, beeswax, paraffin wax, carnauba wax, rice wax, chitin, hydrophobic Examples include starch and polybutylene succinate. As the biodegradable water-insoluble layer (C), shellac is preferable.

Shellac is a natural resin obtained by purifying a resin secreted by a lacquer parasite (Indian lacquer scale) that parasitizes certain plants. Examples of the shellac include those obtained by modifying the natural resin, for example, methacrylate-modified shellac, acrylate-modified shellac, epoxy-modified shellac, urethane-modified shellac, ester-modified shellac, acetyl-modified shellac, and phenol-modified shellac. Particularly preferred are ester-modified shellac, acetyl-modified shellac and methacrylate-modified shellac obtained by the reaction with A.

The beeswax is a wax collected by heating and squeezing a honeycomb and the main component is myricyl palmitate. The carnauba wax is a vegetable wax collected from narnabay palm. The rice wax is a wax oil separated when refining rice oil extracted from rice bran. Examples of the hydrophobic starch include fatty acid ester starch and acetate starch starch.

The surface of the biodegradable water-insoluble layer (C) on the side opposite to the water-soluble resin layer (B) may have water repellency from the viewpoint of preventing liquid from entering. The water repellency preferably has a water contact angle similar to that described in the section of the hydrophobic fine particle layer (A).

In the water-impermeable and water-decomposable sheet of the present invention, the biodegradable water-insoluble layer (C) preferably has a basis weight of about 3 to about 15 g / m ² and about 5 to about 10 g / m 2. More preferably, it has a basis weight of ² or less. If the basis weight is less than about 3 g / m ² , leakage may occur when pressure such as body pressure is applied during use. If the basis weight exceeds about 15 g / m ² , the biodegradability Although the water pressure resistance of the water-soluble layer (C) is improved, there are cases where the sheet becomes hard and the tactile sensation is deteriorated, and the biodegradable water-insoluble layer (C) is not divided into at least two fragments after disposal.

[Water-decomposable substrate layer (D)]
The water-decomposable substrate layer (D) is a layer of a substrate having water-decomposability, which is optionally disposed between the hydrophobic fine particle layer (A) and the water-soluble resin layer (B). Since the water-decomposable substrate layer (D) has high adhesive strength with the hydrophobic fine particle layer (A), the water pressure resistance of the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B) is reduced. Can be improved.
The meaning of “water decomposability” is as described in the section of “sheet having water impermeability and water decomposability” described later.

The water-decomposable substrate layer (D) is not particularly limited as long as it has water-decomposability. Can be mentioned. Examples of the hydrolyzed paper include hydrolyzed tissue obtained by wet papermaking of pulp such as toilet paper. Examples of the water-decomposable nonwoven fabric include a hydrolyzed spunlace nonwoven fabric in which fibers are slightly entangled by water jet treatment of wet papermaking.

Examples of fibers used in the water-decomposable nonwoven fabric include pulp, rayon, cupra, cotton, hemp, wool, silk, polyvinyl alcohol, polyethylene, polypropylene, polyester, nylon, and vinylon.

In the water-impermeable and water-decomposable sheet of the present invention, the water-decomposable substrate layer (D) preferably has a basis weight of about 15 to about 50 g / m ² and about 20 to about 40 g / m ^2. It is more preferable to have the following basis weight. When the basis weight is less than about 15 g / m ² , the strength of the water-decomposable substrate (D) is weak and it may be difficult to integrate with the water-soluble resin layer (B). When the basis weight exceeds about 50 g / m ² , the sheet may become hard and the tactile sensation may be deteriorated, and it takes time for the sheet having water impermeability and water decomposability of the present invention to be hydrolyzed. In some cases, the filter medium may be clogged and / or piping such as pumps and sewers may be clogged.

[Sheet having water impermeability and water decomposability]
The schematic diagram of the cross section of the two aspects of the sheet | seat which has the water-impermeable property and water-disintegration property of this invention is shown in FIG.1 and FIG.2. In FIG. 1, a sheet 1 having water impermeability and water decomposability includes, in order from the top, a hydrophobic fine particle layer (A) 2, a water-soluble resin layer (B) 3, and a biodegradable water-insoluble layer (C) 4. .

Reference numerals

5 and 6 respectively denote a surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B) and a water-soluble resin layer (B) of the biodegradable water-insoluble layer (C). The opposite surface.

The sheet having water impermeability and water decomposability of the present invention has a higher water impermeability on the biodegradable water-insoluble layer (C) side than on the hydrophobic fine particle layer (A) side. The sheet having water permeability and water decomposability is usually used with the biodegradable water-insoluble layer (C) side facing the human body that is more frequently in contact with the liquid.

In FIG. 2, the sheet 1 having water impermeability and water decomposability includes a hydrophobic fine particle layer (A) 2, a water decomposable substrate layer (D) 7, a water-soluble resin layer (B) 3 and biodegradation in order from the top. Water-insoluble layer (C) 4.

Reference numerals

In the sheet having water impermeability and water decomposability according to the present invention, “water impermeability” means water impermeability on the hydrophobic fine particle layer (A) side and water impermeability on the biodegradable water-insoluble layer (C) side. Means both.
The above-mentioned “water decomposability” means a property that disintegrates in water when flowing into a flush toilet. The water decomposability of the sheet having water impermeability and water decomposability of the present invention can be evaluated according to the shake flask method and the dispersion rate described below.

The procedure of the shake flask method is as follows.
Place a 10 cm x 10 cm square sample in a 1000 mL flask containing 800 mL of distilled water, shake the shaker (SHKV-200 manufactured by IWAKI) for 60 minutes at a shaking speed of 240 rpm, and after shaking The condition of the sample is visually evaluated.
The evaluation criteria are as follows.
A: Dispersed to a level where the original shape is not retained.
B: Some original shapes remain, but are dispersed in three or more.
C: The original shape is retained.
The sheet having water impermeability and water decomposability of the present invention is most preferably an evaluation A, and is preferably an evaluation B.

The procedure for measuring the dispersion rate is as follows.
The sample after the shake flask method test is filtered through a 2 mesh (wire diameter: 1.5 mm, opening: 11.2 mm, space ratio: 77.8%) wire mesh, and the dry mass of the sheet before the test is A. , And the dry mass of the sheet fiber remaining on the wire mesh as B, the following formula:
Dispersion rate (%) = 100 × (A−B) / A
Calculate based on

The sheet having water impermeability and water decomposability of the present invention preferably has a dispersion ratio of about 50% by mass or more, more preferably about 60% by mass or more, and about 90% by mass or more. Is more preferred and is most preferably about 100% by weight. This is because if the dispersion ratio is low, the equipment in the septic tank is likely to be entangled, resulting in an obstacle that hinders the normal functioning of the septic tank.

While the sheet having water impermeability and water decomposability of the present invention has water impermeability at the time of use, the mechanism having water decomposability after disposal in water is as follows.
-In use-
(1) When a liquid touches the biodegradable water-insoluble layer (C) side of the water-impermeable and water-decomposable sheet of the present invention, the water-impermeable property of the biodegradable water-insoluble layer (C) Prevents liquid from entering.

(2) When the hydrophobic fine particle layer (A) side of the sheet having water impermeability and water disintegration of the present invention is exposed to wet hands, sweat, liquid leaked due to unforeseen circumstances, etc., hydrophobic Infiltration of the liquid is prevented by the water impermeability of the conductive fine particle layer (A).

-After disposal-
(1) When the sheet having water impermeability and water decomposability of the present invention is disposed in water after use, the fine uneven structure in the hydrophobic fine particle layer (A) is collapsed by being swallowed by a water flow. , Its water repellency is reduced, and then its water impermeability is lost. The hydrophobic fine particles in the hydrophobic fine particle layer (A) are adhered to the water-soluble resin layer (B), the water-degradable substrate layer (D), etc. by van der Waals force. , Collapse easily.
(2) When the water impermeability of the hydrophobic fine particle layer (A) is lost and water penetrates into the inside and has the water-decomposable substrate layer (D), the water-degradable substrate layer (D) Hydrate.
(3) Then, the water-soluble resin layer (B) is dissolved in water, and with the dissolution of the water-soluble resin layer (B), the biodegradable water-insoluble layer (C) is divided into at least two fragments, and Dissolve. The hydrolyzed biodegradable water-insoluble layer (C) is transported along with the water stream and rapidly biodegrades in a septic tank, sewage, etc., usually within 3 months.
The sheet having water impermeability and water decomposability according to the present invention employs different mechanisms for the hydrophobic fine particle layer (A) side and the biodegradable water-insoluble layer (C) side, so Both function and sex.

Although the manufacturing method of the sheet | seat which has the water-impermeable property of this invention and water disintegration is not restrict | limited in particular, For example, as one of the aspects, the following;
Providing a water-soluble resin layer (B);
Laminating the hydrophobic fine particle layer (A) on the water-soluble resin layer (B); and laminating the biodegradable water-insoluble layer (C) on the water-soluble resin layer (B):
Can be mentioned.

In order to prepare the water-soluble resin layer (B), for example, a solution of a resin constituting the water-soluble resin layer (B), for example, an aqueous solution, can be coated on the support substrate by, for example, a slit coater. The melt of the resin constituting the water-soluble resin layer (B) can be formed into a film shape, or the water-soluble resin layer (B) marketed in a film shape can be used as it is.

The hydrophobic fine particle layer (A) is formed on the water-soluble resin layer (B) by coating the solution in which the hydrophobic fine particles are dispersed in a solvent by a method such as spray coating, curtain coating, gravure coating or foam coating. Can be stacked.
Since the hydrophobic fine particle layer (A) needs to maintain water repellency up to a certain water pressure and disintegrate when the certain water pressure is exceeded, it is not a film-like continuous film but a porous discontinuous film. preferable.

The solvent for dispersing the hydrophobic fine particle layer (A) is preferably other than water in consideration of the influence on the water-soluble resin layer (B) and the desired hydrolyzable substrate layer (D). Aliphatic alcohols such as methanol, ethanol, isopropyl alcohol, isobutyl alcohol; ketones such as acetone, ethyl methyl ketone; esters such as ethyl acetate; ethers such as diethyl ether, diisopropyl ether, methyl t-butyl ether; Examples of the hydrocarbons include paraffins; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as toluene.

For example, the biodegradable water-insoluble layer (C) is coated with a solution containing the resin constituting the biodegradable water-insoluble layer (C) by a method such as roll coating, gravure coating, comma coating, or lip coating. Thus, it can be laminated on the water-soluble resin layer (B).
The step of laminating the hydrophobic fine particle layer (A) on the water-soluble resin layer (B) and the step of laminating the biodegradable water-insoluble layer (C) on the water-soluble resin layer (B) are in no particular order. Either may be implemented first.

As another aspect of the manufacturing method of the sheet | seat which has the water-impermeable property and water-decomposability of this invention, following;
Laminating the water-soluble resin layer (B) on the water-decomposable substrate layer (D);
Laminating the hydrophobic fine particle layer (A) on the water-degradable substrate layer (D); and laminating the biodegradable water-insoluble layer (C) on the water-soluble resin layer (B):
Can be mentioned.

The water-soluble resin layer (B) is laminated on the water-decomposable substrate layer (D) by, for example, coating a solution of the resin constituting the water-soluble resin layer (B), for example, an aqueous solution with, for example, a slit coater. can do.
The hydrophobic fine particle layer (A) can be laminated by coating the hydrolyzable substrate layer (D) with the above-mentioned solution in which the hydrophobic fine particles are dispersed in a solvent by the above-described method.
The method for laminating the biodegradable water-insoluble layer (C) on the water-soluble resin layer (B) is as described above.
The step of laminating the water-soluble resin layer (B) on the water-degradable substrate layer (D), the step of laminating the hydrophobic fine particle layer (A) on the water-degradable substrate layer (D), and biodegradation The step of laminating the water-insoluble water layer (C) on the water-soluble resin layer (B) is in no particular order.

In the sheet having water impermeability and water decomposability of the present invention, the basis weight thereof varies depending on the use, but generally it is preferably about 15 to about 100 g / m ² , and preferably about 15 to More preferably, it is about 75 g / m ² and even more preferably about 30 to about 75 g / m ² . If the basis weight is less than about 15 g / m ² , the water impermeability may be inferior, and if it exceeds about 100 g / m ² , the sheet becomes hard and the tactile sensation deteriorates, and / or water decomposability. May be inferior.

The sheet having water impermeability and water decomposability according to the present invention is within the range that does not impair the effects of the present invention, the hydrophobic fine particle layer (A), the water-soluble resin layer (B), the biodegradable water-insoluble layer (C) In addition to the optional three layers and four layers of the water-degradable substrate layer (D), additional layers can be further included. Examples of such additional layers include an additional hydrophobic fine particle layer (A) and an additional water-soluble resin layer (B) on the biodegradable water-insoluble layer (C).
By further laminating the hydrophobic fine particle layer (A) on the biodegradable water-insoluble layer (C), the water-repellent property on the biodegradable water-insoluble layer (C) side is improved, and thus the water impermeability is improved. Can be made. Moreover, by further laminating the water-soluble resin layer (B ′) on the biodegradable water-insoluble layer (C), the biodegradable water-insoluble layer (C) deteriorates with time during storage before use. In addition, when the liquid is absorbed, the water-soluble resin (B ′) dissolves in the liquid, thereby increasing the viscosity of the liquid and enhancing the leakage preventing effect.

The water-impermeable and water-decomposable sheet according to the present invention is used for sanitary products such as sanitary napkins and panty liners, sanitary products such as disposable diapers, urine leak prevention sheets, and urine collecting pads for incontinence patients. be able to.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated, this invention is not limited to these Examples.
The materials used in the following production examples, examples and comparative examples are shown together with abbreviations used in them.
-Hydrophobic fine particle layer (A)-
Nanosilica particles: manufactured by Nikka Chemical Co., Ltd., Adesso WR1
-Water-soluble resin layer (B)-
PVA film: Nippon Synthetic Chemical Co., Ltd., Hi-Selon MS-25, Basis weight: 25 g / m ²
Water-soluble urethane: manufactured by Ohara Palladium Chemical Co., Ltd., AF36
Sulfo-modified polyester: AQ29D manufactured by Eastman Chemical Company
-Biodegradable water-insoluble layer (C)-
Shellac: manufactured by East Japan Paint Co., Ltd., red label bleached shellac varnish-water-degradable substrate layer (D)-
Hydrolytic paper: NBKP 100%, Basis weight: 35 g / m ²

[Production Example 1]
On one side of the PVA film, nanosilica particles were spray-coated to a basis weight of 1.0 g / m ² and dried. Next, shellac was gravure-coated on the surface of the PVA film opposite to that coated with the nanosilica particles so as to have a basis weight of 7.0 g / m ² and dried to produce a sheet 1.

[Production Example 2]
The hydrolytic paper was spray-coated with nanosilica particles to a basis weight of 1.0 g / m ² and dried. Here, when the ventilation resistance value of the hydrolytic paper coated with nano silica particles was measured, it was 0.289 kPa · S / m, and it was confirmed to have air permeability. Next, water-soluble urethane was coated on the surface of hydrolytic paper opposite to the surface coated with nanosilica particles with a slit coater so that the basis weight was 20.0 g / m ² and dried. Here, when the ventilation resistance value of the water-disintegrating paper coated with water-soluble urethane was measured, it had a size exceeding the measurement range. Next, shellac was gravure-coated on the water-soluble urethane layer so as to have a basis weight of 7.0 g / m ² and dried to produce a sheet 2.

[Production Example 3]
A sheet 3 was produced according to Production Example 2 except that the basis weight of shellac was changed to 3.0 g / m ² .
[Production Example 4]
A sheet 4 was produced according to Production Example 2 except that the basis weight of shellac was changed to 15.0 g / m ² .

[Production Example 5]
A sheet 5 was produced according to Production Example 2 except that sulfo-modified polyester was used instead of water-soluble urethane.
Sulfo-modified polyester is a kind of ion-sensitive resin, which shows insolubility under high ion concentration conditions such as in body fluids, but has low ion concentration as in the presence of a large amount of water such as toilets. Under circumstances, it is a resin that exhibits solubility.

[Production Example 6]
On the shellac layer of the sheet manufactured according to the method of Preparation Example 2, as an additional layer, water-soluble urethane is coated with a slit coater so as to have a basis weight of 5.0 g / m ² and dried. 6 was produced.
Table 1 summarizes the outline of the sheets 1 to 6 produced in Production Examples 1 to 6.

[Comparative Production Example 1]
On one side of the PVA film, shellac was gravure-coated so that the basis weight was 7.0 g / m ² and dried to produce a sheet 7.
Since moisture and moisture cause curling and stickiness, humidity control is necessary.
[Comparative Production Example 2]
On one side of the PVA film, shellac is gravure coated to a basis weight of 7.0 g / m ² and dried, and then on the side of the PVA film opposite to the shellac-coated side, shellac is applied. The sheet 8 was manufactured by gravure coating to a basis weight of 7.0 g / m ² and drying.

[Comparative Production Example 3]
One side of the water-disintegrating paper was coated with water-soluble urethane by a slit coater so that the basis weight was 20.0 g / m ² and dried. Next, shellac was gravure-coated on the water-soluble urethane layer so as to have a basis weight of 7.0 g / m ² and dried to produce a sheet 9.
[Comparative Production Example 4]
Shellac was gravure-coated on one side of the hydrolytic paper so that the basis weight was 7.0 g / m ² , and dried to produce a sheet 10.
Table 1 summarizes the outline of the sheets 7 to 10 produced in Comparative Production Examples 1 to 4.

[Examples 1 to 6 and Comparative Examples 1 to 4]
The following tests were performed on the sheets 1 to 10 produced in Production Examples 1 to 6 and Comparative Production Examples 1 to 4.
Test items and test procedures are listed below, and the results are also shown in Table 1.
-Water disintegration-
Evaluation was performed according to the shake flask method and the dispersion rate described above.
In addition, regarding the visual evaluation of the shake flask method, the results of three tests were comprehensively judged.

-Constant temperature and high humidity test-
The sheet was held for 24 hours under the conditions of 40 ° C. and 90% relative humidity, and the warpage caused by the hygroscopicity of the sheet was visually evaluated. In the case where the sheet has hygroscopicity, curling, stickiness, and the like may occur during production, which may cause a reduction in productivity, and thus it may be necessary to strictly control the humidity.
The evaluation criteria are as follows.
A: No curling or stickiness due to moisture absorption B: There is some curling or stickiness due to moisture absorption, but there is no effect on processing. C: Curling or sticking due to moisture absorption is significant and processing is affected.

−Contact angle−
The water contact angle on the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B) was measured using an automatic contact angle meter CA-V type manufactured by Kyowa Interface Science Co., Ltd. The average value of the results of five measurements is adopted as the contact angle value.
-Water pressure resistance-
The water pressure resistance on the hydrophobic fine particle layer (A) side and the water pressure resistance on the biodegradable water-insoluble layer (C) side are evaluated.
In accordance with JIS L 1092, the average value of 10 test results is adopted as the value of the water pressure resistance.

In the sheet 1 of Example 1, the biodegradable water-insoluble layer (C) has a water pressure resistance of 1000 mm or more, and has sufficient water impermeability as the biodegradable water-insoluble layer (C). Moreover, in the sheet 1, the hydrophobic fine particle layer (A) has a contact angle of 157 ° and a water pressure resistance of 42 mm, and has sufficient water impermeability as the hydrophobic fine particle layer (A). Furthermore, it was confirmed that the sheet 1 of Example 1 also has sufficient water decomposability because the visual evaluation by the shake flask method is A and the dispersion rate is 100%.

In the sheet 2 of Example 2, the water resistance of the hydrophobic fine particle layer (A) is improved as compared with the sheet 1. This seems to be due to the fact that the bond between the nanosilica particles and the hydrolytic paper is higher than the bond between the nanosilica particles and the PVA film.

From Example 3, it can be seen that when the amount of shellac is reduced to 3.0 g / m ² , the water decomposability is improved, and the water pressure resistance of the biodegradable water-insoluble layer (C) is slightly reduced. From this, it can be seen that when the amount of shellac is increased to 15.0 g / m ² , the water disintegration shown by the shake flask method and the dispersion ratio is slightly inferior, but the water resistance is greatly improved. Accordingly, the amount of shellac can be appropriately increased or decreased depending on the application in which the sheet having water impermeability and water decomposability of the present invention is used.
Example 5 shows that the same effect is obtained when the water-soluble resin layer (B) is changed from PVA to sulfo-modified polyester. In addition, it can be seen from Example 6 that even when water-soluble urethane is further laminated as an additional layer on the biodegradable water-insoluble layer (C), the water decomposability does not decrease so much.

In Comparative Example 1 corresponding to the water-soluble waterproof film described in Patent Document 1, it can be seen that the PVA film surface has a contact angle of 0 ° and a water pressure resistance of 3 mm, and hardly has water impermeability. Furthermore, the sheet | seat 7 of the comparative example 1 was remarkable in the curvature of the sheet | seat in a constant temperature high humidity test.
In Comparative Example 2 corresponding to an embodiment in which a biodegradable water-insoluble layer is laminated on both sides of the PVA film layer described in [0058] of Patent Document 1, although water impermeability is excellent, water decomposability is almost the same. It turns out that it does not have.

From Comparative Example 3, it can be seen that if the hydrophobic fine particle layer (A) is not provided, the surface not having the hydrophobic fine particle layer (A) is inferior in water impermeability. From the comparative example 4, when it does not have a water-soluble resin layer (B), it is inferior in water decomposability | degradability as it is clear also from the evaluation C by a shake flask method and 5% of a dispersion rate. This seems to be because there is no water-soluble resin layer (B) that plays a role of dividing the biodegradable water-insoluble layer (C) into at least two fragments.

1 Sheet having water impermeability and water decomposability 2 Hydrophobic fine particle layer (A)
3 Water-soluble resin layer (B)
4 Biodegradable water-insoluble layer (C)
5 Surface of hydrophobic fine particle layer (A) opposite to water-soluble resin layer (B) 6 Surface of biodegradable water-insoluble layer (C) opposite to water-soluble resin layer (B) 7 Water-decomposable group Material layer (D)

Claims

A sheet having water impermeability and water decomposability, comprising a hydrophobic fine particle layer (A), a water-soluble resin layer (B), and a biodegradable water-insoluble layer (C),
The water-soluble resin layer (B) is between the hydrophobic fine particle layer (A) and the biodegradable water-insoluble layer (C) and adhered to the biodegradable water-insoluble layer (C),
The hydrophobic fine particle layer (A) has a fine uneven structure formed by laminating hydrophobic fine particles on the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B). And a biodegradable water-insoluble layer (C) is a water-insoluble and water-soluble resin layer (B) having a water contact angle of more than 90 ° and disintegrating by being swallowed by a water stream. ) Is dissolved in water and is divided into at least two pieces.
A sheet characterized by that.
The sheet according to claim 1, wherein the hydrophobic fine particles include inorganic fine particles.
The sheet according to claim 1 or 2, wherein the hydrophobic fine particles have an average particle diameter of 1 to 100 nm.
The sheet according to any one of claims 1 to 3, wherein the hydrophobic fine particle layer (A) has a basis weight of 0.1 to 3 g / m 2 .
The sheet according to any one of claims 1 to 4, further comprising a water-decomposable substrate layer (D) between the hydrophobic fine particle layer (A) and the water-soluble resin layer (B).
The sheet according to claim 5, wherein the water-decomposable substrate layer (D) comprises a material selected from the group consisting of hydrolyzed paper and hydrolyzable nonwoven fabric.
The biodegradable water-insoluble layer (C) comprises a material selected from the group consisting of shellac, polylactic acid, polycaprolactone, beeswax, paraffin wax, carnauba wax, rice wax, chitin, hydrophobic starch and polybutylene succinate; The sheet according to any one of claims 1 to 6.
The water-soluble resin layer (B) is selected from the group consisting of water-soluble urethane, polyvinyl alcohol polymer, polyacrylamide, polyacrylic acid polymer, polyethylene oxide, vinyl ether polymer, sulfo-modified polyester, polyurethane derivative and polysaccharide. The sheet according to any one of claims 1 to 7, comprising a material.
The sheet according to any one of claims 1 to 8, wherein the surface of the hydrophobic fine particle layer (A) opposite to the water-soluble resin layer (B) has a water pressure resistance of 30 to 300 mm.
The sheet according to any one of claims 1 to 9, wherein the surface of the biodegradable water-insoluble layer (C) opposite to the water-soluble resin layer (B) has a water pressure resistance of 400 mm or more.
The sheet according to any one of claims 1 to 10, wherein a dispersion rate (%) after the shake flask test is 50% by mass or more.
The sheet according to any one of claims 1 to 11, further comprising a water-soluble resin layer (B) as an additional layer on the biodegradable water-insoluble layer (C).
Providing a water-soluble resin layer (B);
Laminating the hydrophobic fine particle layer (A) on the water-soluble resin layer (B); and laminating the biodegradable water-insoluble layer (C) on the water-soluble resin layer (B):
The manufacturing method of the sheet | seat of Claim 1 containing this.
Laminating the water-soluble resin layer (B) on the water-decomposable substrate layer (D);
Laminating the hydrophobic fine particle layer (A) on the water-degradable substrate layer (D); and laminating the biodegradable water-insoluble layer (C) on the water-soluble resin layer (B):
The manufacturing method of the sheet | seat of Claim 5 containing this.