JPH0790795A - Sheet disintegrating in water - Google Patents

Abstract

PURPOSE:To provide a sheet disintegrating in water, having high paper strength in a state impregnated with a water-containing organic solvent, especially exhibiting extremely low wet paper strength, keeping excellent disintegrating performance and disposable into a toilet, etc., after use. CONSTITUTION:This sheet disintegrating in water, having increased swelling degree of a water-insoluble swellable carboxymethylcellulose alkali metal salt and/or a water-insoluble swellable carboxymethylcellulose, exhibiting extremely low wet strength and having excellent disintegrating performance in water is produced by making a paper from a compounded paper stock containing water-insoluble swellable carboxymethylcellulose alkali metal salt and/or water- insoluble swellable carboxymethylcellulose and sodium bicarbonate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-decomposable sheet which can be used for cleaning articles impregnated with a water-containing organic solvent.

[0002]

2. Description of the Related Art Sheets used for conventional cleaning articles and the like are wet paper strengthening agents such as epoxidized polyamide resin and melamine-formaldehyde resin so that they can withstand use in a state of being impregnated with a water-containing organic solvent. Is given. Therefore, although it has sufficient strength when used, if it is discarded in a flush toilet, sink, sewage after use,
If water is not dissolved, it may clog the piping and cause trouble.
In addition, polyvinyl alcohol for the purpose of maintaining water decomposability,
Although a water-soluble binder such as sodium carboxymethyl cellulose is used, it has water-decomposability and paper strength in a dry state, but when impregnated with a water-containing organic solvent, the paper strength is remarkably reduced and it is difficult to put it into practical use.

For this reason, a special material and method have been required to obtain a sheet having a suitable water decomposability and a paper strength that can be practically used even when impregnated with a water-containing organic solvent. For example, a method of using a polyvinyl alcohol fiber whose saponification degree is adjusted as a binder, a method of using a carboxymethylcellulose calcium salt as a binder as in JP-A-1-168999, and the like are known. However, although the sheets obtained by these methods have an appropriate degree of water disintegration, the strength of paper when impregnated with a water-containing organic solvent is low, and it is insufficient especially at a high water content.

[0004]

The present applicant previously applied for a patent for a sheet having high paper strength when impregnated with a water-containing organic solvent in Japanese Patent Application No. 3-133711, but there is a problem in water-wet paper strength. It was The present invention is a further improvement of the patent of the prior application, the paper strength is high when impregnated with a water-containing organic solvent and does not break during use, and especially the water-wet paper strength is very low, after use flush toilet, sink, sewage, etc. It provides a sheet that immediately dissolves in water even after being discarded and does not cause troubles such as clogging in the piping.

[0005]

Means for Solving the Problems As a result of intensive studies by the present inventor, the present invention contains water-insoluble swelling carboxymethyl cellulose alkali metal salt or / and water-insoluble swelling carboxymethyl cellulose (hereinafter abbreviated as binder CMC) and sodium bicarbonate. After papermaking of the compounded paper stock, by impregnating it with a water-containing organic solvent containing polyvalent metal ions, the paper strength at the time of impregnation with a water-containing organic solvent is high, especially the water-wet paper strength is very low, and it is water-degradable. Invented a sheet with superior performance.

The present invention will be described in detail below. The binder CMC used in the present invention has a low degree of substitution (hereinafter abbreviated as DS) and a water-insoluble swelling property, or a general DS, unlike water-soluble CMC that is generally commercially available.
Even if it is (0.5 to 1.0), it is a water-insoluble swelling agent in which the contained carboxymethyl group is partially neutralized with an alkali metal salt. The type of alkali metal is sodium,
Although there are potassium, lithium, etc., sodium is preferable from the viewpoint of low cost. In addition to the alkali metal salts, ammonium salts, amine salts and the like can be used, but the alkali metal salts are preferable because they generate ammonia gas and amine gas during the production.

The fibrous material constituting the sheet is not particularly limited, and wood pulp, non-wood pulp, rayon fiber, synthetic fiber and the like are used, but a biodegradable material is preferable in consideration of environmental issues.

As a method for producing the sheet, a conventionally known method may be used, and a wet papermaking method is generally suitable.

The mixing ratio of the binder CMC and the fiber material is not particularly limited, but is usually 2:98 to 40:
A range of 60 weight ratio is preferred. If the blending ratio of the binder CMC is small, the paper strength at the time of impregnation with a water-containing organic solvent is lowered, and if it is too large, papermaking becomes difficult.

The amount of the sodium bicarbonate added is 0.1 to 0.1% of the amount of the binder CMC before the drying step during paper making.
Blend so that 10.0 wt% is present. 0.1% by weight
Below, there is no effect on the strength of wet paper strength and water disintegration.
On the other hand, if it is 10.0% by weight or more, there is no difference in the effect and it is wasted, and it becomes difficult to make the paper.

Then, after the sheet is formed, the alkaline metal portion of the carboxymethyl group is replaced with an alkaline earth metal ion such as calcium ion or a polyvalent metal ion. In other words, unless substitution is performed with polyvalent metal ions, the hydrophilicity of the binder CMC itself reduces the paper strength when impregnated with a water-containing organic solvent, particularly a high water-content organic solvent.
Therefore, after exhibiting the ability as a binder, it is replaced with an alkaline earth metal ion or a polyvalent metal ion to form a cross-linking complex to suppress hydrophilicity. This method may be the method described in Japanese Patent Application No. 3-133711.

The metal ions added to the water-containing organic solvent include
There are alkaline earth metal ions such as calcium, magnesium and barium, and polyvalent metal ions such as nickel, iron, copper and cobalt. These metal ions are supplied as water-soluble salts such as hydroxides, chlorides, sulfates and nitrates, but in this case as well, it is preferable to select in consideration of environmental problems.

The water-containing organic solvent with which the sheet is impregnated is a mixed solution of alcohols such as methanol, ethanol, propanol, ethylene glycol and propylene glycol, hydrocarbons such as liquid paraffin and water and, if necessary, a surfactant. A substance that contributes to the cleaning effect such as, a bactericide, and a fragrance may be added.

The mixing ratio of water and the organic solvent is determined depending on the purpose of use, but it is generally in the range of 10:90 to 95: 5 weight ratio. For example, if importance is attached to the bactericidal effect, it is preferable to increase the content of alcohols such as methanol, ethanol and propanol. If the purpose is to remove general stains in the home, it is preferable to increase the water content.
The amount of the water-containing organic solvent with which the sheet is impregnated is not particularly limited and may be determined in consideration of workability, safety, cost and the like.

The water-decomposable sheet of the present invention thus obtained has a high paper strength when impregnated with a water-containing organic solvent and does not break during use. In particular, it has a very low wet paper strength and is washed with water after use. Even if it is discarded in the toilet, sink, sewage, etc., it immediately dissolves and has excellent performance that does not cause troubles such as clogging in the piping.

[0016]

Although the logical elucidation of the present invention is still insufficient, it is considered as follows. The water-insoluble swellable binder CMC used in the present invention has a property that the degree of swelling is small in acidic, neutral or slightly alkaline water, and conversely, it is large in medium or strong alkali. In the wet papermaking method, since the papermaking is generally acidic or neutral, the binder CMC has a small degree of swelling, so that the papermaking is not difficult. If the swelling degree of the binder CMC is large, however, even though it is water-insoluble, the releasability of the wire part and the felt part is insufficient, and papermaking becomes difficult.

Considering the degree of swelling from the viewpoint of water-wet strength, the greater the degree of swelling of the binder CMC when wet with water, the weaker the binder strength and the lower the strength of water-wet strength.

In order to solve the conflicting problems,
The relationship between the swelling degree of the binder CMC and sodium bicarbonate is important. An aqueous solution of sodium bicarbonate has the property of changing to carbon dioxide by releasing carbon dioxide at 65 ° C.

That is, when sodium bicarbonate is blended with the stock material containing the binder CMC, the sodium bicarbonate does not change because the temperature is room temperature until the felt part stage, and the stock material is in an acidic, neutral or slightly alkaline state. Therefore, the binder CMC has a small degree of swelling and does not adversely affect the papermaking property.

At the dry part stage, sodium bicarbonate is overheated to 110 to 130 ° C., so carbon dioxide is released to change to sodium carbonate, and the paper stock becomes a medium or strong alkali, so that the binder CMC has a large swelling degree. As a result, it is considered that when the binder CMC is re-wetted with water, the degree of swelling is large, so that the binder strength becomes weak and the water-wetting paper strength becomes low.

[0021]

EXAMPLES Examples will be shown below, but the present invention is not limited thereto. The evaluation method is as follows. "Paper strength when impregnated with water-containing organic solvent" Sheet width 10mm,
Cut into strips with a length of 120 mm and add 1 part of calcium chloride.
Aqueous ethanol solution containing 3% by weight (ethanol: water = 3
0:70 weight ratio)
Immediately measure the paper strength.

A "water-wet paper strength" sheet with a width of 10 mm,
Cut into strips with a length of 120 mm and add 1 part of calcium chloride.
Immersion in an aqueous ethanol solution containing 30 wt% for 30 minutes, and further immersion in water for 5 minutes, the paper strength is immediately measured.

"Water-decomposability": inner diameter 3.2 cm, length 30 cm
Ion-exchanged water (150 ml) was added to the colorimetric tube, and a 2 x 2 cm sheet preliminarily dipped in an ethanol aqueous solution containing 1% by weight of calcium chloride for 30 minutes was inserted and the rubber stopper was inserted. Then, the colorimetric tube was turned upside down. Compare the collapsed states. For comparison, a commercially available water-decomposable wet tissue was used, and this water-decomposability was made good.

[0024]

Examples 1, 2, 3 and Comparative Example 1 In Example 1, 44.8 g of pulp (NBKP, beating degree 720 mlc, s, f) was used.
And binder CMC (DS = 0.39, pH = 6.5)
11.2 g and 500 g of sodium bicarbonate are dissolved in 60 l of water to prepare a blended stock. 600 ml of this mixed paper material is JIS
Paper was made with a tappy standard sheet machine according to P 8209 to obtain a sheet of 30 g / m ² . At this time, the amount of CMC in the wet paper was 0.112 g, the amount of sodium bicarbonate was 1.47 × 10 ⁻³ g, and the amount of sodium bicarbonate was C.
It becomes 1.31% by weight with respect to MC.

In Example 2, 300 g of sodium bicarbonate was added,
Others were the same as in Example 1. At this time, the amount of CMC in the wet paper was 0.112 g, and the amount of sodium bicarbonate was 8.8.
It becomes 3 × 10 ⁻⁴ g, and the amount of sodium bicarbonate becomes 0.79% by weight with respect to CMC.

In Example 3, 100 g of sodium bicarbonate was added,
Others were the same as in Example 1. At this time, the amount of CMC in the wet paper was 0.112 g, and the amount of sodium bicarbonate was 2.9.
It becomes 4 × 10 ⁻⁴ g, and the amount of sodium bicarbonate becomes 0.26% by weight with respect to CMC.

In Comparative Example 1, paper was made without using sodium bicarbonate. Others were the same as in Example 1. The results are shown in Table 1.

[0028]

[Table 1]

In this example, the amount of sodium bicarbonate added was changed variously. It can be seen that the wet paper strength is low and the water disintegration is excellent.

[Example 4 and Comparative Examples 2 and 3] 44.8 g of pulp (NBKP, beating degree 720 mlc, s, f) and binder C
11.2 g of MC (DS = 0.42, pH = 6.6) and 500 g of sodium bicarbonate are dissolved in 60 l of water to prepare a mixed stock material. 600 ml of this mixed paper material is added to JIS P 8209.
Paper was made with a tappy standard sheet machine to obtain a sheet of 30 g / m ² . CMC in wet paper at this time
The amount is 0.112g, sodium bicarbonate is 1.47 × 1
0 ^-3 g, and the amount of sodium bicarbonate becomes 1.31% by weight relative to CMC.

In Comparative Example 2, paper was made without using sodium bicarbonate. Others were the same as in Example 4.

In Comparative Example 3, papermaking was carried out without using sodium bicarbonate, and calcium chloride was not added to the hydrous ethanol solution. Others were the same as in Example 4.

The results are shown in Table 2.

[0033]

[Table 2]

This embodiment is a binder CMC having a different DS.
It was used. It can be seen that the paper strength at the time of impregnation with a water-containing organic solvent is high and the water-wet paper strength is low, and the water decomposability is excellent.

[0035]

Example 5 and Comparative Example 4 44.8 g of pulp (NBKP, beating degree 720 mlc, s, f) and binder CMC
(DS = 0.42, pH = 6.6) 5.6 g and 100 g of sodium bicarbonate are dissolved in 60 l of water to prepare a mixed stock material.
28 g of paper is made from 600 ml of this mixed paper material by a tappy standard sheet machine according to JIS P 8209.
A sheet of / m ² was obtained. At this time, the amount of CMC in the wet paper was 0.056 g, and the amount of sodium bicarbonate was 2.94 × 10.
^-4 g, and the amount of sodium bicarbonate was 0.
It becomes 53% by weight.

In Comparative Example 4, paper was made without using sodium bicarbonate. Others were the same as in Example 5.

The results are shown in Table 3.

[0038]

[Table 3]

In this example, the amount of binder CMC used was reduced. It can be seen that the wet paper strength is low and the water disintegration is excellent.

[0040]

Industrial Applicability The water-decomposable sheet of the present invention has high paper strength when impregnated with a water-containing organic solvent and does not break when used, and particularly has very low water-wet paper strength, and has a flush toilet after use, a sink, sewage, etc. Even if it is discarded, it will be immediately hydrolyzed, and it will not cause troubles such as clogging in the piping.

Claims (2)

[Claims] 1. A water-decomposable sheet prepared by making a paper stock containing a water-insoluble carboxymethyl cellulose alkali metal salt or / and a water-insoluble carboxymethyl cellulose and sodium bicarbonate. 2. The amount of sodium bicarbonate is 0.1 to 10.0% by weight of the amount of the water-insoluble carboxymethyl cellulose alkali metal salt or / and the water-insoluble carboxymethyl cellulose in the step before the drying step. 1. Water-degradable sheet.