JP3296989B2 - Water disintegrable 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 relates to a water-disintegrable sheet which is suitable for wiping off dirt and whose tissue collapses when discarded in a large amount of water, and a method for producing the same.

[0002]

2. Description of the Related Art It is called wet wipes, etc., and when it is thrown into the water of a flush toilet etc. after wiping off stains of hands and objects, the tissue collapses and the constituent fibers are dispersed or dissolved,
Water-disintegrable sheets that can be washed off as they are are known. Here, the water dissolvability is sometimes referred to as water dispersibility, water disintegration, or water solubility. Such a water-disintegrable sheet is required to have high strength when used in a wet state and rapid dispersibility when thrown into a large amount of water. In order to balance these strength and dispersibility,
Water-soluble or water-swellable carboxymethylcellulose or a metal salt thereof, in particular, a sodium salt of carboxymethylcellulose may be used as a binder to produce a water-decomposable sheet.

For example, in the production method disclosed in Japanese Patent Application Laid-Open No. 1-168999, a sheet using a metal salt of carboxymethylcellulose as a binder is impregnated with a liquid substance such as an alcohol or a surfactant.

Further, Japanese Patent Application Laid-Open Nos.
In the production method disclosed in JP-A--25792 or the like, a sheet containing a water-soluble polyvalent metal salt such as an alkaline earth metal, manganese, or zinc and an organic solvent is added to a sheet using a metal salt of carboxymethyl cellulose as a binder. Impregnated.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. HEI 1-168.
As in the production method disclosed in Japanese Patent Publication No. 999, it is difficult to prevent the carboxymethylcellulose metal salt from being eluted into the water-disintegratable sheet in a wet state only by using an alcohol or a surfactant, and the strength required for the water-disintegratable sheet is reduced. To do so, the concentration of these alcohols and activators must be quite high. However, a high concentration of these drugs is not preferable because it also increases the skin irritation.

On the other hand, Japanese Patent Application Laid-Open Nos.
As disclosed in JP-A--25792, when a sheet using a metal salt of carboxymethyl cellulose as a binder is impregnated with a water-soluble polyvalent metal salt, a polyvalent metal ion ionized from the water-soluble polyvalent metal salt becomes Because of its high ability to form salts with carboxymethylcellulose, carboxymethylcellulose polyvalent metal salts are easily produced. The resulting carboxymethylcellulose polyvalent metal salt has a lower solubility or swelling property than ordinary carboxymethylcellulose monovalent metal salt, and therefore, the sheet has a high wet strength and, at the same time, has low water solubility and water dispersibility. Tend to.

Accordingly, an object of the present invention is to provide a water-disintegrable sheet capable of satisfying both water solubility or water swellability and wet strength.

[0008]

Means for Solving the Problems One of the present invention for solving the above-mentioned problems is to provide a base sheet comprising water-dispersible fibers and water-swellable carboxymethylcellulose and / or a salt thereof, comprising at least water; A 0.5% by weight aqueous solution is impregnated with a liquid component comprising one or more water-soluble alkali metal salts and / or water-soluble ammonium salts having a pH of 5 to 9 and being in a wet state. Water disintegrable sheet.

[0009]

Another aspect of the present invention relates to a water-dispersible fiber and a fiber.
Carboxymethylcellulose and / or its salts
At least water and 0.5% by weight water
One or more of the solutions exhibiting a pH of 5 to 9
Water-soluble alkali metal salt and / or water-soluble ammonium
Make sure that the liquid component consisting of salt is impregnated and wet.
The feature is the water disintegrable sheet. These water disintegrable sheets
In a preferred embodiment of the invention, the fibrous cal
Boxymethylcellulose and / or its salts are swelled in water
Sex. The carboxymethyl cellulose and / or
Is the salt in the dry weight of the water-disintegrable sheet,
Accounts for 0.1 to 50% by weight. The water-soluble alkali
The metal salt is a sodium salt. The impregnating liquid
The pH of the components is adjusted to 5.5-7.0.

[0011] Still another aspect of the present invention is a water-dispersible fiber.
And water-swellable carboxymethylcellulose and / or
At least water and 0.5 wt.
1 or 2 types in which the pH of the aqueous solution by weight is 5 or more and 9 or less
At least one water-soluble alkali metal salt and / or
Impregnated with liquid component consisting of monium salt to make it wet
And a method for producing a water-disintegrable sheet.
Still another aspect of the present invention is directed to water-dispersible fibers and fibrous
Consisting of boxymethylcellulose and / or its salt
At least water and a 0.5% by weight aqueous solution
One or more water-soluble compounds having a pH of 5 to 9
Alkali metal salts and / or water-soluble ammonium salts
Characterized by being impregnated with a liquid component
In the method for producing a water-disintegrable sheet. Further of the present invention
The other is water-dispersible fiber and water-swellable or water-insoluble.
Carboxymethylcellulose and / or its salt
Obtained by adding a base in the manufacturing process of a base sheet made of
At least water and a 0.5% by weight aqueous solution
One or two or more aqueous solutions exhibiting a pH of 5 to 9
Water-soluble alkali metal salt and / or water-soluble ammonium salt
And impregnated with a liquid component consisting of
The present invention relates to a method for producing a water-disintegrable sheet. These water dissolving properties
In a preferred embodiment of the invention relating to a method for manufacturing a sheet
The fibrous carboxymethylcellulose and / or
Is a salt that is water-swellable. The liquid component has a pH
It is adjusted to 5.5 to 7.0. The carboxymethyl
Cellulose and / or a salt thereof, wherein the water-decomposable sheet
Occupies 0.1 to 50% by weight of the dry weight of
Impregnated. The water-soluble alkali metal salt is sodium
Salt.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As a water-disintegrable sheet according to the present invention, a base sheet comprising a water-dispersible fiber and a binder is used.

As the water-dispersible fiber, pulp fiber is suitable because it is easy to handle and does not cost much, but natural fibers such as linen and cotton having a fiber length easily dispersible in water and regenerated fibers such as rayon And semi-synthetic fibers such as acetate and synthetic fibers such as polyester and nylon can be used alone or in combination.

As the binder, carboxymethylcellulose and / or a salt thereof, particularly an alkali metal salt of carboxymethylcellulose such as a sodium salt of carboxymethylcellulose is used.

These binders may be either water-soluble or water-swellable. However, when paper is made by mixing fibers and a binder, carboxymethylcellulose which is fibrous and water-swellable is used. It is desirable to use the sodium salt. Further, carboxymethylcellulose having low water swellability or water insolubility and / or a salt thereof is used as a binder, and the water dissolving agent disclosed in Japanese Patent Application No. 7-285479 or Japanese Patent Application No. 7-285480 filed by the same applicant as the present invention. Based on the method for producing a functional sheet, a binder having an improved water solubility by adding a base in the step of producing the sheet can also be an object of the present invention. The sheet may be produced by spraying or applying water-soluble carboxymethylcellulose and / or a salt thereof to a fiber web such as a card web or an airlaid web, in addition to the papermaking method.

The fiber and the binder are 99.9: 0.1
It is preferable that the weight ratio is about 50:50. If the amount of the binder is smaller than this ratio, the required wet strength for the sheet cannot be obtained. On the other hand, if the ratio of the binder is larger than this ratio, it is difficult to obtain a uniform distribution of the fibers in the sheet, and the cost is increased unnecessarily. Two or more sheets obtained by a papermaking method or the like can be used after being stacked and integrated by embossing or an adhesive.

A sheet composed of water-dispersible fibers and a binder is impregnated with a liquid component composed of at least water and a water-soluble alkali metal salt and / or ammonium salt to obtain a wet state water-disintegrable sheet of the present invention. Can be The addition of the alkali metal salt or ammonium salt may be performed before the step of wetting the sheet, after the step of wetting the sheet, or may be performed simultaneously with the wetting of the sheet. Nevertheless, a solution in which an alkali metal salt or an ammonium salt is dissolved is prepared in advance, and the salt is added to the sheet by impregnating the solution, whereby the salt is uniformly distributed throughout the sheet. It becomes easy to do.

The amount of the liquid to be impregnated varies depending on the type and mixing ratio of fibers and binders, the basis weight, thickness, and density of the sheet, the composition of the impregnating liquid, the use of the water-disintegrable sheet, and the like. 150 to 300% by weight, preferably 175 to 275% by weight.

The effect of adding an alkali metal salt and / or an ammonium salt will be described below by taking a water-disintegrable sheet using a sodium salt of carboxymethylcellulose as a binder as an example.

The carboxymethylcellulose sodium salt as a binder is in an ionization equilibrium state represented by the following chemical formula in a water-disintegratable sheet in a wet state.

[0021]

Embedded image That is, under humid conditions, sodium carboxymethylcellulose undergoes ionization and swells or dissolves, significantly lowering the function as a binder, and lowering the wet strength of the sheet. However, when a solution in which an alkali metal salt or an ammonium salt is dissolved is added to this sheet, the ion concentration increases in the above equilibrium, and the equilibrium moves to the left. That is, since the ionization of carboxymethylcellulose sodium salt is suppressed, a decrease in the function of this salt as a binder can be prevented. However, when this sheet is discarded in a large amount of water such as a flush toilet, a septic tank, a sewer, or the like, the ion concentration decreases, so that ionization of carboxymethylcellulose sodium salt proceeds and the sheet is rapidly dispersed or dissolved.

The liquid to be impregnated preferably contains an organic solvent in addition to the salts. This is because the organic solvent can suppress swelling and elution of carboxymethylcellulose and / or a salt thereof.

Examples of the organic solvent include monohydric alcohols such as methanol, ethanol and propanol, polyhydric alcohols such as propylene glycol, isoprene glycol and polyethylene glycol, and derivatives thereof. These organic solvents can be used as a mixture of two or more kinds.

The water-soluble alkali metal salt and ammonium salt used in the present invention are those whose aqueous solution shows weak acidity to weak alkalinity, specifically, 0.5% by weight aqueous solution of p.
Those in which H represents 5 or more and 9 or less are preferable. Those having a pH outside this range may irritate the user's skin.
Use of an alkali metal salt or an ammonium salt having a pH of more than 9 is not preferable because carboxymethyl cellulose and / or a salt thereof may be denatured.

Examples of usable alkali metal salts include sodium and / or potassium chlorides, bromides, iodides, sulfates, thiosulfates, bicarbonates, phosphates, nitrates and other inorganic salts, acetates, and the like. Propionate, salicylate, phthalate, lactate, malate, tartrate, citrate, oxalate, malonate, succinate, aspartate, glutamate, thioglycolate, ethylenediamine Organic salts such as tetraacetate, and their complex salts, mixtures, hydrates, and the like. Further, ammonium salts such as ammonium chloride, ammonium sulfate, and ammonium acetate can also be used. An alkali metal salt and an ammonium salt can be used as a mixture, or a complex salt of both can be used.

The amount of the alkali metal salt or ammonium salt used depends on the type of salt, strength required for the sheet, water dispersibility, and the like. It preferably accounts for 1 to 20% by weight.
If the amount of salt is small, the required wet strength of the sheet cannot be obtained. When the amount of salt is large, the cost is wasted.

Depending on the types and amounts of these alkali metal salts and ammonium salts, the pH of the impregnating solution may be biased toward the alkali side. In such a case, it is preferable to adjust the pH from weakly acidic to neutral by appropriately adding an acid. For example, when impregnating with an aqueous solution of 10% by weight of propylene glycol, 1% by weight of ethanol and 5% by weight of sodium citrate, the pH of the liquid is 8.6, so that 10% by weight of propylene glycol and 1% by weight of ethanol are used. %,
If the aqueous solution is obtained by adding 0.2% by weight of citric acid to 5% by weight of sodium citrate, the pH becomes 6.5. There is almost no adverse effect on the water-disintegrable sheet due to such pH adjustment (see Examples 3-1 and 3-2 and Comparative Example 3-1 described later).

In the present invention, the above-mentioned alkali metal salts and ammonium salts can be used in combination with other salts, for example, alkaline earth metal salts. As an example, a sheet impregnated with 225% by weight of an aqueous solution containing 20% by weight of propylene glycol, 1% by weight of ethanol and 0.2% by weight of calcium chloride by spraying has a high wet strength and a remarkable dispersibility in flowing water. become worse. But,
A sheet sprayed with 225% by weight of an aqueous solution containing 20% by weight of propylene glycol, 1% by weight of ethanol, 0.2% by weight of calcium chloride and 5% by weight of sodium aspartate has the same wet strength as the former sheet, and has a fluidity. The dispersibility in water is better than the former (see Example 5-1 and Comparative Example 5-1).

The water-disintegratable sheet according to the present invention may contain a surfactant, a bactericide, an antibacterial agent, an abrasive, a coloring agent,
One or more of a thickener, a humectant, a fragrance, a deodorant, a sizing agent and the like can be contained.

Next, the details of the water-disintegrable sheet according to the present invention will be described based on examples.

[0031]

EXAMPLES Example 1-1 79.6% by weight of softwood kraft pulp, sodium carboxymethylcellulose (Nichirin Kagaku Kogyo: D.C.
S. = 0.43, pH = 5.9) 8.8% by weight, soda ash 11. Using a 6% by weight raw material and a paper machine,
A sheet having 0 g / m ² and a crepe rate of 40% was produced, three of these sheets were stacked, embossed, and integrated to obtain a base sheet. Propylene glycol / ethanol / sodium chloride / water = 10 /
A liquid prepared at 1 / 3.8 / 85.2 (% by weight) (pH =
5.9) was impregnated with 225% of the dry weight of the substrate sheet by spraying to obtain a water-disintegrable sheet of the present invention.

Example 1-2 79.6% by weight of softwood kraft pulp, sodium carboxymethylcellulose (Nichirin Chemical Industries:
S. = 0.43, pH = 5.9) Using 8.8% by weight and soda ash 11.6% by weight as raw materials, and using a paper machine to obtain a basis weight of 3
A sheet having 0 g / m ² and a crepe rate of 40% was produced, three of these sheets were stacked, embossed, and integrated to obtain a base sheet. Propylene glycol / ethanol / sodium sulfate / water = 10 /
A liquid prepared at 1 / 4.6 / 84.4 (% by weight) (pH =
6.2) was spray impregnated with 225% of the dry weight of the base sheet to obtain a water-disintegrable sheet of the present invention.

Comparative Example 1-1 79.6% by weight of softwood kraft pulp, sodium salt of carboxymethylcellulose (Nichirin Kagaku Kogyo: D.I.
S. = 0.43, pH = 5.9) 8.8% by weight, soda ash 11. Using a 6% by weight raw material and a paper machine,
A sheet having 0 g / m ² and a crepe rate of 40% was produced, three of these sheets were stacked, embossed, and integrated to obtain a base sheet. This sheet was impregnated with a liquid (pH = 6.0) prepared in propylene glycol / ethanol / water = 10/1/89 (% by weight) by spraying only 225% of the dry weight of the base sheet. Was obtained.

[Example 2-1] 81.8% by weight of softwood kraft pulp, sodium salt of carboxymethylcellulose (D.I.
S. = 0.42, pH = 6.0) 9.1% by weight of soda ash and 9.1% by weight of soda ash as raw materials, and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. For this sheet, polyethylene glycol # 1500 / ethanol / ethylparaben / methylparaben / potassium citrate / water = 10/1 / 0.0
The liquid (pH = 7.8) prepared to 5 / 0.1 / 5 / 83.85 (% by weight) was impregnated with 250% of the sheet dry weight by spraying to obtain a water-disintegrable sheet of the present invention.

Example 2-2 Needle tree kraft pulp 81.8% by weight, carboxymethylcellulose sodium salt (manufactured by Nichirin Kagaku Kogyo Co .;
S. = 0.42, pH = 6.0) 9. 1% by weight, soda ash 1% by weight as a raw material and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. For this base sheet, polyethylene glycol # 1500 / ethanol / ethylparaben /
Methyl paraben / potassium citrate / water = 10/1 /
A solution (pH = 8.0) prepared to 0.05 / 0.1 / 10 / 78.85 (% by weight) was added to 25% of the substrate sheet dry weight.
It was impregnated with 0% by spray to obtain a water-disintegrable sheet of the present invention.

Comparative Example 2-1 81.8% by weight of softwood kraft pulp, sodium salt of carboxymethylcellulose (D.C.
S. = 0.42, pH = 6.0) 9. 1% by weight, soda ash 1% by weight as a raw material and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. For this base sheet, polyethylene glycol # 1500 / ethanol / ethylparaben /
Methyl paraben / water = 10/1 / 0.05 / 0.1 / 8
The liquid (pH = 6.3) prepared to 8.85 (% by weight)
The sheet was impregnated with 250% of the dry weight of the sheet by spraying to obtain a water-disintegrable sheet of Comparative Example.

Example 3-1 81.8% by weight of softwood kraft pulp, sodium carboxymethylcellulose (Nichirin Kagaku Kogyo: D.I.
S. = 0.42, pH = 6.0) 9. 1% by weight, soda ash 1% by weight as a raw material and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. Propylene glycol / ethanol / sodium citrate / water = 10
/ 1/5/84 (% by weight) (pH = 8.
6) was impregnated with 225% of the dry weight of the substrate sheet by spraying to obtain a hydrolyzable sheet of the present invention.

Example 3-2 81.8% by weight of softwood kraft pulp, sodium carboxymethylcellulose (Nichirin Kagaku Kogyo: D.I.
S. = 0.42, pH = 6.0) 9. 1% by weight, soda ash 1% by weight as a raw material and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. A liquid (pH = 6.5) prepared with propylene glycol / ethanol / sodium citrate / citric acid / water = 10/1/5 / 0.2 / 83.8 (% by weight) with respect to this base sheet. Was spray impregnated with 225% of the dry weight of the base sheet to obtain a hydrolyzable sheet of the present invention.

Comparative Example 3-1 81.8% by weight of softwood kraft pulp, sodium salt of carboxymethylcellulose (D.C.
S. = 0.42, pH = 6.0) 9. 1% by weight, soda ash 1% by weight as a raw material and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. Propylene glycol / ethanol / water = 10/1/89 (% by weight)
The liquid (pH = 6.0) prepared above was impregnated with 225% of the dry weight of the substrate sheet by spraying to obtain a water-disintegrable sheet of Comparative Example.

Example 4-1 77.6% by weight of softwood kraft pulp, sodium carboxymethylcellulose (Nichirin Kogyo: DS.
= 0.42, pH = 5.9) 8.6% by weight, soda ash 1
Using 3.8% by weight as a raw material, a basis weight of 36.
A sheet having a thickness of 5 g / m ² and a crepe rate of 30% was manufactured, three of these sheets were stacked, embossed, and integrated to obtain a base sheet. Propylene glycol / ammonium acetate / acetic acid / water = 10/4.
8 / 0.2 / 85 (% by weight) (pH = 6.
0) was impregnated with 225% of the dry weight of the substrate sheet by spraying to obtain a hydrolyzable sheet of the present invention.

[Example 4-2] 77.6% by weight of softwood kraft pulp, sodium carboxymethylcellulose (Nichirin Chemical Industries, Ltd .;
S. = 0.42, pH = 5.9) 8.6% by weight and 13.8% by weight of soda ash as raw materials, and using a paper machine, a basis weight of 3
6.5 g / m ² , a sheet having a crepe ratio of 30% was produced,
Three sheets were stacked, embossed, and integrated to obtain a base sheet. Propylene glycol / ammonium acetate / acetic acid / water = 10 /
A liquid prepared at 9.4 / 0.6 / 80 (% by weight) (pH =
5.9) was impregnated with 225% of the dry weight of the substrate sheet by spraying to obtain a water-disintegrable sheet of the present invention.

[Example 4-3] 77.6% by weight of softwood kraft pulp, sodium carboxymethylcellulose (DS, manufactured by Nichirin Kogyo Co., Ltd.)
= 0.42, pH = 5.9) 8.6% by weight, soda ash 1
Using 3.8% by weight as a raw material, a basis weight of 36.
A sheet having a thickness of 5 g / m ² and a crepe rate of 30% was manufactured, three of these sheets were stacked, embossed, and integrated to obtain a base sheet. Propylene glycol / ammonium acetate / acetic acid / water = 10/1
Liquid prepared to 4.2 / 0.8 / 75 (wt%) (pH =
6.0) was impregnated with 225% of the dry weight of the substrate sheet by spraying to obtain a water-disintegrable sheet of the present invention.

[Comparative Example 4-1] 77.6% by weight of softwood kraft pulp, sodium salt of carboxymethylcellulose (D.I.
S. = 0.42, pH = 5.9) 8.6% by weight and 13.8% by weight of soda ash as raw materials, and using a paper machine, a basis weight of 3
6.5 g / m ² , a sheet having a crepe ratio of 30% was produced,
Three sheets were stacked, embossed, and integrated to obtain a base sheet. A liquid (pH = 6.2) adjusted to propylene glycol / water = 110/90 (% by weight) was added to the base sheet at a dry weight of 225 of the base sheet.
% By spraying to obtain a water-disintegrable sheet of Comparative Example.

Example 5-1 81.8% by weight of softwood kraft pulp, sodium carboxymethylcellulose (Nichirin Kagaku Kogyo: D.I.
S. = 0.42, pH = 6.0) 9. 1% by weight and 9.1% by weight of soda ash as raw materials, and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. For this base sheet, propylene glycol / ethanol / calcium chloride / sodium aspartate / water = 20/1 / 0.2 / 5 / 73.8.
(% By weight) by spraying the liquid (pH = 6.9) by spraying 225% of the dry weight of the base sheet.
The hydrolyzed sheet of the present invention was obtained.

Example 5-2 81.8% by weight of softwood kraft pulp, sodium salt of carboxymethyl cellulose (D.C.
S. = 0.42, pH = 6.0) 9. 1% by weight and 9.1% by weight of soda ash as raw materials, and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. A solution (pH = 7.7) prepared with propylene glycol / ethanol / calcium chloride / sodium glutamate / water = 20/1 / 0.2 / 5 / 73.8 (weight% ratio) was applied to the base sheet. 225% of the dry weight of the substrate sheet was impregnated with a spray to obtain a water-disintegrable sheet of the present invention.

[Example 5-3] 81.8% by weight of softwood kraft pulp, sodium carboxymethylcellulose (Nichirin Kagaku Kogyo: D.I.
S. = 0.42, pH = 6.0) 9.1% by weight of soda ash and 9.1% by weight of soda ash as raw materials, and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. For this substrate sheet, propylene glycol / ethanol / calcium chloride / EDTA-3
The liquid (pH = 6.8) prepared so that sodium / water = 20/1 / 0.2 / 5 / 73.8 (% by weight) is impregnated with 225% of the dry weight of the substrate sheet by spraying, and the present invention is applied. Water dissolution sheet was obtained.

Example 5-4 81.8% by weight of softwood kraft pulp, sodium carboxymethylcellulose (Nichirin Kagaku Kogyo: D.I.
S. = 0.42, pH = 6.0) 9. 1% by weight and 9.1% by weight of soda ash as raw materials, and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. A solution (pH = 8.5) prepared to propylene glycol / ethanol / calcium chloride / sodium acetate / water = 20/1 / 0.2 / 5 / 73.8 (% by weight) was applied to the base sheet. The base sheet was impregnated with 225% of the dry weight of the sheet by spraying to obtain a water-disintegrable sheet of the present invention.

[Comparative Example 5-1] 81.8% by weight of softwood kraft pulp, sodium carboxymethylcellulose (Nichirin Chemical Industries, Ltd .;
S. = 0.42, pH = 6.0) 9. 1% by weight and 9.1% by weight of soda ash as raw materials, and a basis weight of 30 using a paper machine.
A sheet having a g / m ² and a crepe ratio of 30% was produced, three sheets of this sheet were stacked, embossed, and integrated to obtain a base sheet. Propylene glycol / ethanol / calcium chloride / water = 20/1
/0.2/78.8 (wt%) (pH =
4.6) was impregnated with 225% of the dry weight of the base sheet by spraying to obtain a water-disintegrable sheet of Comparative Example.

The following items were evaluated for each of the water-disintegrable sheets of Examples and Comparative Examples obtained as described above. (1) Dispersibility of water-disintegrable sheet in fluidized water A piece of water-disintegrable sheet cut to 10 cm x 10 cm in a wet state is put into a 300 ml glass beaker containing 300 ml of ion-exchanged water, and stirred by a magnetic stirrer (rotation). (Several 600 rpm), and the disintegration of the structure of the water-disintegratable sheet and the dispersion state of the fibers were observed with time. The observation results were evaluated as follows.

A: The sheet is fragmented in less than 50 seconds, and is sufficiently resistant to use as a water-disintegrable sheet.

：: The sheet is fragmented in 50 seconds or more and less than 100 seconds, and can be used as a water-disintegrable sheet.

×: The sheet does not shred when the sheet is shorter than 100 seconds, and is difficult to use as a water-disintegrable sheet.
Or impossible. (2) Wet breaking strength A water-disintegratable sheet piece in a wet state cut into a width of 25 mm and a length of 150 mm was chucked at a distance of 100 mm and a tensile speed of 100.
The wet breaking strength when pulled at a rate of mm / min was measured in directions perpendicular to each other on the sheet pieces, and the average value of the strength in both directions was calculated. In this evaluation, if the average breaking strength of the sheet was 150 g or more, it was evaluated that the sheet could be used as a water-disintegrable sheet. The results of the evaluation are as shown in Tables 1 and 2, and can be arranged as follows. (1) According to the comparison between Examples 1-1 and 1-2 and Comparative Example 1-1, when a sodium salt is used, the wet rupture strength of the sheet can be improved without substantially deteriorating the dispersibility. (2) By comparing Examples 2-1 and 2-2 with Comparative Example 2-1, even when a potassium salt is used, it is possible to improve the wet breaking strength of the sheet without substantially deteriorating the dispersibility. it can. (3) When the pH of the liquid to be impregnated is increased by using a sodium salt as in Example 3-1, if the acid is added as in Example 3-2, the pH is set to near neutral. , And good dispersibility and wet rupture strength can be maintained. (4) From the comparison between Examples 4-1 and 4-2 and 4-3 and Comparative Example 4-1, even when an ammonium salt and an acid are used, good dispersibility and high wet rupture strength can be obtained. . (5) When an alkaline earth metal salt such as calcium chloride is added to the liquid to be impregnated as in Comparative Example 5-1, even if the wet rupture strength of the sheet increases, at the same time, the dispersibility is extremely poor. Become. However, Examples 5-1, 5-2, and 5
When a sodium salt is added as in -3 and 5-4, both high wet breaking strength and good dispersibility can be achieved.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

The water-disintegrable sheet in the wet state according to the present invention uses water-swellable or water-insoluble carboxymethylcellulose and / or a salt thereof as a binder, ionization, a indicating a specific pH range
Since it is suppressed by the lukali metal salt and / or ammonium salt , a good wet rupture strength is exhibited when the sheet is used.

When this sheet is poured into a large amount of flowing water, the concentration of the alkali metal salt and / or ammonium salt rapidly decreases, the binder swells quickly, the structure of the sheet collapses, and the fibers are dispersed. I do. Such a sheet can be easily treated in a flush toilet, a septic tank, a sewer, or the like.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masanori Monobe 1531-7 Takada, Wadahama, Toyohama-cho, Mitoyo-gun, Kagawa Prefecture 7 Within the Development Headquarters of Unicharm Co., Ltd. 1531-7 Takasuka Inside Development Headquarters, Unicharm Corporation (56) References JP-A-2-149237 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 11/00-27 / 42 D04H 1/04 D06M A47K 7 / 00,10 / 00

Claims (13)

(57) [Claims] 1. A substrate sheet comprising a water-dispersible fiber and a water-swellable carboxymethylcellulose and / or a salt thereof, wherein at least water and at least one kind of a 0.5% by weight aqueous solution having a pH of 5 to 9 or A water-decomposable sheet characterized by being impregnated with a liquid component comprising two or more water-soluble alkali metal salts and / or water-soluble ammonium salts and in a wet state. 2. A water-dispersible fiber and fibrous carboxymethyl.
Base sheet made of cellulose and / or its salt
At least water and the pH of the 0.5 wt% aqueous solution are 5 or more.
One or more water-soluble alkali golds showing the above 9 or less
Liquid consisting of a genus salt and / or a water-soluble ammonium salt
Water degradability characterized by being impregnated with moist components
Sheet. 3. The fibrous carboxymethyl cellulose.
And / or the salt thereof is water-swellable.
Resolvable sheet. 4. The carboxymethyl cellulose and / or
Or a salt thereof, in the dry weight of the water disintegratable sheet, claims 1-3 Neu occupying 0.1 to 50 wt%
The water-disintegrable sheet according to any one of the preceding claims. Wherein said water-disintegratable sheet according to any one of claims 1 to 4 water-soluble alkali metal salt is sodium salt. 6. The pH of the impregnated liquid component is 5.
6. The method according to claim 1, wherein the pressure is adjusted to 5 to 7.0.
The water-disintegrable sheet according to Item. 7. A substrate sheet comprising a water-dispersible fiber and water-swellable carboxymethylcellulose and / or a salt thereof, wherein at least water and at least one kind of a 0.5% by weight aqueous solution having a pH of 5 or more and 9 or less. A method for producing a water-disintegratable sheet, comprising impregnating a liquid component comprising at least two water-soluble alkali metal salts and / or water-soluble ammonium salts to obtain a wet state. 8. A water-dispersible fiber and fibrous carboxymethyl.
Base sheet made of cellulose and / or its salt
And at least water and the pH of a 0.5% by weight aqueous solution are 5 or less.
One or more water-soluble alkali golds showing the above 9 or less
Liquid consisting of a genus salt and / or a water-soluble ammonium salt
Hydrolysis, characterized by impregnating the components to make them wet
Method for producing a functional sheet. 9. The fibrous carboxymethyl cellulose
And / or the salt thereof is water-swellable.
Manufacturing method of dissolvable sheet. 10. Water-dispersible fiber and water-swellable or water-insoluble
Carboxymethylcellulose and / or its salt
Obtained by adding a base in the manufacturing process of a base sheet made of
At least water and a 0.5% by weight aqueous solution
One or two or more aqueous solutions exhibiting a pH of 5 to 9
Water-soluble alkali metal salt and / or water-soluble ammonium salt
And impregnated with a liquid component consisting of
A method for producing a water-disintegrable sheet. 11. The liquid component has a pH of 5.5 to 7.5.
The production method according to any one of claims 7 to 10 , which is adjusted to 0. 12. the carboxymethylcellulose and / or a salt thereof, in the dry weight of the water disintegratable sheet, according to any one of claims 7 to 11 for impregnation to occupy 0.1 to 50 wt% Production method. 13. The method according to any one of the water-soluble claim 7-12 alkali metal salt is sodium salt.