JP3205706B2 - Method for manufacturing wet wipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a water-disintegratable wet wipe having excellent dispersibility or solubility in water.

[0002]

2. Description of the Related Art Conventionally, wet wipes are well known.
Further, a water-dispersible or water-decomposable sheet material that can be dispersed or dissolved and thrown away as it is thrown into water such as a flush toilet is also well known. Here, the water dispersibility and the water dissolvability are synonymous. When the wet wipes are water-dispersible, they have the contradictory properties of high strength when used in a wet state and quick dispersibility when thrown into a large amount of water. There must be. In order to achieve both the strength and the dispersibility, the wet wipes disclosed in JP-A-1-168999 use water-disintegrated paper mixed with water-insoluble carboxymethylcellulose, particularly a calcium salt thereof. In the wet wipes disclosed in JP-A-2-149237, water-disintegrated paper containing a water-soluble binder such as a water-soluble carboxymethylcellulose alkali metal salt,
It is impregnated with a detergent containing polyvalent metal ions such as alkaline earth metals, manganese and zinc and an organic solvent. JP 5
In the wet wipes disclosed in JP-A--25792, a sheet formed using a water-insoluble swellable carboxymethylcellulose alkali metal salt is added to a water-containing organic solvent containing polyvalent metal ions such as alkaline earth metals, nickel and iron. Is impregnated.

[0003]

Conventionally, carboxymethylcellulose and its salt used as a binder are:
In general, as the degree of substitution (DS) and the pH increase, it changes from water-insoluble to swellable, and it is well known that it becomes water-soluble. In order for a wet wipe composed of a sheet formed using carboxymethylcellulose and / or a salt thereof as a binder to have good water dispersibility, the binder only needs to have high swellability or water solubility. May be used to manufacture wet wipes using the above-mentioned conventional knowledge.

[0004] However, wet wipes using a highly swellable or water-soluble binder cause the binder to swell or dissolve during use or storage, resulting in reduced wet strength. However, it may not be practical.

On the other hand, as taught by the above-mentioned prior art, water-swellable or water-soluble carboxymethylcellulose to which a polyvalent metal ion is added and / or a salt thereof becomes a carboxymethylcellulose polyvalent metal salt, and is swellable by water. , The solubility is reduced. Then, the carboxymethylcellulose and / or its salt and the salt-forming reaction with the polyvalent metal ion are more easily dissociated from carboxymethylcellulose and / or its salt, in other words, DS,
The higher the pH, in other words the higher the swelling or water solubility, the faster the process. That is, the higher the carboxymethylcellulose and / or its salt, the higher the DS and pH, and the higher the swelling property or water solubility, the more remarkable the effect of adding a polyvalent metal ion.
The wet strength of the wet wipes may be higher than when a binder having a low H is used.

In the production of a sheet for wet wipes using carboxymethylcellulose or a salt thereof as a binder,
As disclosed in JP-A-2-149237, if carboxymethylcellulose or a salt thereof is water-soluble, when the paper and the fiber are mixed with a binder in water, the amount of the binder attached to the obtained sheet is small. In some cases, the strength of the sheet does not improve as much as the amount of the binder used. Instead of such a papermaking method, a binder can be sprayed and adhered to the sheet after papermaking. However, since aqueous solutions of carboxymethylcellulose and salts thereof are generally high in viscosity, it is difficult to spray uniformly.

As disclosed in JP-A-5-25792, when a water-insoluble or water-swellable binder is used, if the binder has a high swellability, it is difficult to uniformly mix the fibers with the fibers. Further, if the binder is not water-insoluble or has a low swelling property, the amount of adhesion to the formed sheet increases, but such a binder has a weak force of binding fibers to each other, and it is difficult to obtain high wet strength.

Accordingly, an object of the present invention is to provide a method for producing a wet wipe that can achieve both good wet strength and water dispersibility.

[0009]

In order to solve the above-mentioned problems, the present invention is based on the premise that a liquid containing at least carboxymethylcellulose and / or a salt thereof and water-dispersible fibers and containing a polyvalent metal ion is provided. Is a method for producing a wet wipes impregnated with a.

[0010] In such a premise, the place to which the present invention is characterized by obtaining a sheet by papermaking a mixture of low water-swellable or water-insoluble carboxymethyl cellulose and / or its salt and water-dispersible fibers, carbon dioxide in this sheet Nato
Was added potassium Contact this carboxymethylcellulose said carboxymethylcellulose and / or its salt
And / or a salt of carboxymethylcellulose having a high water swellability or water solubility as compared with its salt ,
Water-swellable or water-insoluble carboxy of the mixture in water
Methylcellulose and / or a salt thereof may be used in the sheet
Water swelling or water obtained by adding sodium carbonate to
Low compared to soluble carboxymethylcellulose salts
An object of the present invention is to impregnate the sheet with a liquid containing polyvalent metal ions , which is water-swellable or water-insoluble .

[0011] By using sodium carbonate,
The low water-swellable or water-insoluble carboxymethylcellulose and / or a salt thereof can be changed to a highly swellable or water-soluble one after sheet forming. When the sheet containing such a change is impregnated with a liquid containing a polyvalent metal ion, a carboxymethyl cellulose polyvalent metal salt is rapidly formed. The resulting wet wipes will have good wet strength due to the presence of this metal salt. The polyvalent metal salt of carboxymethyl cellulose dissociates quickly and dissolves or swells when poured into a large amount of water such as flush toilets, septic tanks, sewers, etc., so that the water dispersibility of wet wipes is substantially impaired. Not.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Raw materials used in the production method according to the present invention include carboxymethylcellulose and / or a salt thereof, and water-dispersible fibers that can be formed into a sheet together with them. As the fiber, it is preferable to use pulp fiber, but in addition, linen, natural fiber such as wool and regenerated fiber such as rayon fiber,
Semi-synthetic fibers such as acetate, and synthetic fibers such as nylon and polyester can also be used.

For these fibers, relatively low water-swellable or water-insoluble carboxymethylcellulose and / or a salt thereof, preferably D.I. S. = 0.30-0.
Carboxymethylcellulose having a pH of 60 and a pH ≧ 5.0 and / or a salt thereof is used as a binder.
D. S. Is less than 0.30, which is not preferable because the effect of improving the swellability by adding a base is small. D. S. Is greater than 0.60
Extremely easy to swell or water-soluble,
The amount of binder attached to the sheet made is small.
If the pH is lower than 5.0, the amount of the base added to improve the swellability of the binder increases, which is not preferable.

The weight ratio of the binder to the water-dispersible fiber is from 2:98 to 45:55, preferably from 2:98.
98 to 20:80. If the amount of the binder is smaller than this, the function as the binder may not be sufficiently exhibited. On the other hand, if the amount is large, the amount of polyvalent metal ions added to temporarily suppress the swelling and dissolution of the binder increases, so that an increase in production cost cannot be avoided.

The base added to change the binder into a highly water-swellable or water-soluble binder may be any base, but sodium carbonate is used in consideration of safety and cost during sheet production. Is preferred. In order to add a base to the sheet after papermaking, an aqueous solution of the base may be sprayed or applied to the wet sheet.

By impregnating the thus obtained sheet with a liquid containing polyvalent metal ions, the wet wipes of the present invention can be obtained. The metal ions used are 2
Valent metal ions, especially calcium, magnesium,
Zinc and the like are desirable. It is also possible to use iron ions, aluminum ions, copper ions, etc., but in these cases, the metal salt of carboxymethyl cellulose becomes insoluble or non-swellable in water in a very small amount. , It is difficult to adjust its usage.

In order to obtain a liquid containing these divalent metal ions, a water-soluble divalent metal salt such as calcium chloride, magnesium sulfate, or zinc sulfate may be dissolved in water. The concentration of these metal salts is desirably about 0.1 to 10% by weight. If the concentration is lower than 0.1% by weight, the wet strength required for wet wipes cannot be obtained, and
If the amount is more than 10% by weight, the water dispersibility of the wet wipes may be significantly impaired.

The liquid to be impregnated in the wet wipes preferably contains an organic solvent. By containing an organic solvent, swelling or dissolution of carboxymethylcellulose and / or a salt thereof during use of wet wipes can be further suppressed. 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 liquid containing divalent metal ions may be used as a surfactant, a bactericide, an antibacterial, a bacteriostat, a pH adjuster, an abrasive, a coloring agent, a thickener, depending on the use of the wet wipes. ,
One or two or more humectants, fragrances, deodorants, sizing agents, etc. may be contained.

The method of manufacturing a wet wipes according to the present invention will be described below with reference to embodiments.

[0021]

EXAMPLE 1-1 Papermaking softwood pulp (NBKP) and sodium carboxymethylcellulose (DS = 0.50, pH = 7.3, manufactured by Nichirin Kagaku Kogyo Co., Ltd.) were 87.5 / 1.
A sample having a dry weight ratio of 2.5 was mixed and dispersed in tap water. This sample solution was formed by a small test machine, and an aqueous solution containing sodium carbonate equivalent to 2.4% of the dry weight of sodium carboxymethylcellulose was added to the obtained wet sheet by 2.5 times the dry weight of the sheet. The volume was sprayed and impregnated. Next, the sheet was dried at 110 ° C. for 90 seconds using a rotating drum type drier to obtain a basis weight of 40 g /
to obtain a dried sheet of m ^2. On this sheet, calcium chloride / isoprene glycol / ion exchange water = 3/10/8
7 (weight ratio) was sprayed and impregnated with a liquid 2.5 times the sheet dry weight, and allowed to stand at 20 ° C. for 24 hours to obtain a wet wipe.

[0022]

Example 1-2 Except that the composition of the liquid to be spray-impregnated on the dry sheet was magnesium sulfate / isoprene glycol / ion-exchanged water = 3/10/87 (weight ratio).
Wet wipes were obtained under the same conditions as in Example 1-1.

[0023]

Example 1-3 Example 1 was repeated except that the composition of the liquid to be spray-impregnated on the dry sheet was zinc sulfate / isoprene glycol / ion-exchanged water = 3/10/87 (weight ratio).
Under the same conditions as in -1, a wet wipe was obtained.

[0024]

Comparative Example 1-1 The same procedure as in Example 1-1 was carried out except that the composition of the liquid to be spray-impregnated into the dry sheet was sodium sulfate / isoprene glycol / ion-exchanged water = 3/10/87 (weight ratio). Wet wipes were obtained under the conditions.

[0025]

Comparative Example 1-2 The composition of the liquid to be spray-impregnated into the dry sheet is isoprene glycol / ion exchange water = 10 /
A wet wipe was obtained under the same conditions as in Example 1-1 except that the weight was 90 (weight ratio).

[0026]

Example 2-1 Softwood pulp (NBKP) for papermaking and sodium carboxymethylcellulose (DS = 0.43, pH = 6.1, manufactured by Nichirin Kagaku Kogyo) at 87.5 / 1.
A sample having a dry weight ratio of 2.5 was mixed and dispersed in tap water. This sample solution was paper-formed by a small test paper machine, and an aqueous solution containing sodium carbonate equivalent to 4.0% of the dry weight of sodium carboxymethylcellulose was added to the obtained wet sheet by 2.5 times the dry weight of the sheet. The volume was sprayed and impregnated. Next, the sheet was dried at 110 ° C. for 90 seconds using a rotating drum type drier to obtain a basis weight of 40 g /
to obtain a dried sheet of m ^2. Calcium chloride / propylene glycol / ion exchange water = 0.5 / 30
A liquid consisting of /69.5 (weight ratio) was sprayed and impregnated 2.5 times the dry weight of the sheet, and allowed to stand at 20 ° C for 24 hours to obtain a wet wipe.

[0027]

Example 2-2 A wet wipe was obtained under the same conditions as in Example 2-1 except that the amount of sodium carbonate was 8.0% of the dry weight of sodium carboxymethylcellulose.

[0028]

Comparative Example 2-1 A wet wipe was obtained under the same conditions as in Example 2-1 except that the aqueous solution of sodium carbonate was not impregnated by spraying. The wet wipes obtained in these Examples and Comparative Examples were evaluated as follows. (1) Evaluation of water dispersibility A wet wipe piece of 10 cm × 10 cm was put into a 300 ml glass beaker containing 300 ml of ion-exchanged water, and stirred with a magnetic stirrer (rotation speed 600 r).
pm), the state of dispersion of the wet wipes was observed over time. The observation results were evaluated as follows.

A: The paper fragment is fragmented within 100 seconds.

B: The piece of paper is not subdivided within 100 seconds. (2) Evaluation of wet tensile strength A wet wipe paper strip having a width of 25 mm and a length of 150 mm was chucked at a distance of 100 mm and a pulling speed of 100 mm / min.
The tensile strength at the time of pulling was measured. If the breaking strength was at least 300 g, the wet wipes would not be insufficient in practical use.

Table 1 shows the evaluation results of the example and the comparative example. Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-
2, and Examples 2-1 to 2-2 and Comparative example 2-
As compared with 1, the wet strength of the wet wipes impregnated with the liquid containing the polyvalent metal ion is remarkably increased, and the water dispersibility is at a level at which there is no problem. However, wet wipes impregnated with only a monovalent metal ion or a liquid containing no metal ion have insufficient wet strength.

[0032]

[Table 1]

[0033]

In the method for producing wet wipes according to the present invention, the wet wipes are obtained by mixing relatively low water-swellable or water-insoluble carboxymethylcellulose and / or a salt thereof with water-dispersible fibers as a binder. It is easy to attach the required amount of binder to the sheet. Such a binder becomes highly water-swellable or water-soluble by the addition of a base after papermaking,
Rapid dissolution or dispersion of the wet wipes becomes possible. Further, the salt between the binder and the polyvalent metal ion formed by impregnating the sheet containing the binder with the base added with the liquid containing the polyvalent metal ion temporarily increases the wet strength when using the wet wipes. Improve.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masanori Monobe 2-1-2-11-711, Kamenoko, Kakegawa-shi, Shizuoka (56) References JP-A-6-101191 (JP, A) JP-A-7-90795 (JP, A) JP-A-6-192991 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (5)

(57) [Claims] 1. A method for producing a wet wipe comprising at least carboxymethylcellulose and / or a salt thereof and a water-dispersible fiber and impregnated with a liquid containing a polyvalent metal ion, comprising: a low water swelling property or a low water insolubility property. A sheet of a mixture of carboxymethylcellulose and / or a salt thereof and water-dispersible fibers is obtained to obtain a sheet, and sodium carbonate is added to the sheet to convert the carboxymethylcellulose and / or a salt thereof to the carboxymethylcellulose and / or
Compared to the salt and high salt water swellable or water-soluble carboxymethyl cellulose, the mixture in the papermaking
Low water swelling or water insoluble carboxymethyl cellulose
And / or a salt thereof is added to the sheet with sodium carbonate.
Water-swellable or water-soluble carb
Less water swelling than xymethylcellulose salt
Water-insoluble, and the sheet is further impregnated with a liquid containing a polyvalent metal ion. 2. The low water swellable or water insoluble carb
Xymethylcellulose and / or its salts can be obtained from D.I.
S. = 0.30-0.60, pH ≧ 5.0
Item 1. The production method according to Item 1. 3. The method according to claim 1, wherein the polyvalent metal ion is a divalent metal ion. 4. The method according to claim 1, wherein the liquid containing the polyvalent metal ion is an aqueous solution of a polyvalent metal salt. 5. The liquid according to claim 1, wherein the liquid contains an organic solvent.
5. The method according to any one of the above items.