JP2745750B2 - Method for producing aqueous solution of cationic thermosetting resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is useful as a paper wet strength improver, producing a cationic thermosetting resin aqueous solution having a high resin concentration and excellent stability. It is about the method.

<Conventional Technology> Polyamide polyamine-epichlorohydrin resin, which is a cationic thermosetting resin, is widely used as a paper wet strength improver. This resin is usually used in the form of an aqueous solution, but for production, storage, transportation, and the like, it is preferable that the resin concentration in the aqueous solution be high. However, when the resin concentration is increased, the stability of the resin aqueous solution is reduced, and the resin aqueous solution is easily gelled in a short time. Therefore, a method for improving the stability and concentration of this aqueous resin solution is disclosed in
-19715. In this method, a metal salt having a higher charge density than sodium is added to an aqueous resin solution to form a complex compound of the resin and the metal, which is then made acidic or neutral. According to this method, a stable polyamide polyamine-epichlorohydrin resin aqueous solution having a resin solid content of 20% by weight or more is obtained.

<Problems to be Solved by the Invention> However, in this method, since the amount of the complexing metal added to the aqueous resin solution is as large as 10 to 50% or more of the weight of the polymer, a large amount of precipitation may occur during storage. Insolubles may appear on the liquid surface. In addition, a large amount of metal enters the factory wastewater during papermaking, and furthermore, a large amount of metal is contained in the paper itself, which is not preferable in terms of toxicity particularly when heavy metals are used as the metal.

The present inventors have shown that, as well as exhibiting an excellent effect as a paper wet strength improver, they do not cause sedimentation or the like with the passage of time, have no problem in toxicity, and have a high concentration of polyamide polyamine having excellent stability. We studied diligently to produce an aqueous solution of epichlorohydrin resin. As a result, when a polyamide polyamine-epichlorohydrin resin produced under specific conditions is used, and a salt of a specific metal is used, a high-concentration polyamide having excellent stability even when the amount of the metal salt added is small. The present inventors have found that an aqueous solution of a polyamine-epichlorohydrin resin can be obtained, and that the problems of precipitation and toxicity due to aging can be solved, leading to the present invention.

<Means for Solving the Problem> That is, the present invention relates to a method in which a molar ratio of an aliphatic dicarboxylic acid and a polyalkylene polyamine having a molar ratio of 1: 1.0 to 1.2 is adjusted to a viscosity of 400 to 50% by weight of a 50% by weight aqueous solution of a produced polyamide polyamine at 25 ° C. The reaction was carried out so as to be 1000 cps. The obtained polyamide polyamine was mixed with epichlorohydrin 1.6 to 1.7 mol times the amount of the secondary amino group in the obtained polyamide polyamine, and the viscosity at 25 ° C. of a 30% by weight aqueous solution of the product was 150 to 150. Reaction to be 500 cps, the resulting polyamide polyamine-epichlorohydrin resin aqueous solution, a metal salt selected from the group consisting of aluminum, copper and nickel, the metal weight in the metal salt is 0.1 to the resin solid content to the resin solids It is present so as to be 2.0% by weight, and the pH of the aqueous resin solution is adjusted to 2.0 to 5.0.

A method for producing a cationic thermosetting resin aqueous solution having a resin concentration of 30% by weight or more.

The aqueous solution of a cationic thermosetting resin in which a metal salt is present according to the present invention is a polyamide polyamine-epichlorohydrin resin produced by the above-described method.

As the aliphatic dicarboxylic acid used for the production of the polyamide polyamine, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid and the like can be mentioned, but adipic acid is preferable industrially. Suitable polyalkylene polyamines include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, iminobispropylamine and the like. The reaction molar ratio between the aliphatic dicarboxylic acid and the polyalkylene polyamine is in the range of 1: 1.0 to 1.2.

In the polycondensation of an aliphatic dicarboxylic acid and a polyalkylene polyamine, sulfonic acids are preferably used as a catalyst. Examples of the sulfonic acids used for the catalyst include sulfuric acid, benzenesulfonic acid, and paratoluenesulfonic acid. The amount of the catalyst to be used is appropriately 0.005 to 0.1 mole times with respect to the polyalkylene polyamine, preferably
It is 0.01 to 0.05 mole times. The above catalysts may be used alone or in combination of two or more.

The temperature in the polycondensation reaction between the aliphatic dicarboxylic acid and the polyalkylene polyamine is 100 to 250 ° C., preferably 130 ° C.
~ 200 ° C is appropriate, and the viscosity at 25 ° C when the resulting polyamide polyamine is a 50% by weight aqueous solution is 400
Continue the reaction until ~ 1000 cps. The viscosity at 25 ° C of a 50% by weight aqueous solution of the resulting polyamide polyamine is 400 cps.
If the viscosity is lower, the aqueous solution of the cationic thermosetting resin, which is the final product, does not exert a sufficient wet paper strength-improving effect, while if the viscosity exceeds 1,000 cps, the stability of the aqueous resin solution of the final product is reduced. , Often leads to gelation.

The polyamide polyamine thus obtained is then subjected to a reaction with epichlorohydrin, which is usually carried out in an aqueous solution having a reactant concentration of 50% by weight or less.
In order to obtain a product having a resin concentration of 30% by weight or more, the reaction is preferably performed in an aqueous solution having a reactant concentration of 30% by weight or more.

In this reaction, epichlorohydrin is used in a molar amount of 1.6 to 1.7 times the secondary amino group in the polyamide polyamine. If the molar ratio of epichlorohydrin to secondary amino group in the polyamide polyamine exceeds 1.7, the cationic thermosetting resin aqueous solution as the final product will not exert a sufficient wet paper strength improving effect, and unreacted epichlorohydrin Is increased, which is not preferable in terms of odor. On the other hand, if the molar ratio is less than 1.6, the stability of the final aqueous resin solution over time is reduced, which often leads to gelation. This reaction is carried out so that the viscosity of a 30% by weight aqueous solution of the product at 25 ° C. becomes 150 to 500 cps. If the viscosity is lower than 150 cps, the cationic thermosetting resin aqueous solution, which is the final product, will not exhibit a sufficient wet paper strength improving effect, while if it exceeds 500 cps, the stability of the final resin aqueous solution will decrease. However, when added to the pulp slurry during the papermaking process, strong foaming is involved, which not only makes the papermaking operation difficult but also impairs the paper formation.

In the present invention, the polyamide polyamine-epichlorohydrin resin aqueous solution obtained as described above, aluminum, a metal salt selected from the group consisting of copper and nickel, the weight of the metal in the metal salt with respect to the resin solids An aqueous solution of a cationic thermosetting resin is obtained by adjusting the pH of the aqueous resin solution to 2.0 to 5.0 by allowing it to be present in an amount of 0.1 to 2.0% by weight.

The metal salt added to the aqueous resin solution is a salt of aluminum, copper or nickel, and two or more of these may be used. The salt is not particularly limited as long as it is soluble in water, and examples thereof include sulfates, nitrates, chlorides, and bromides. These metal salts need only be present in the aqueous solution of the polyamide polyamine-epichlorohydrin resin obtained as described above, and the timing of their addition is not particularly limited. For example, when synthesizing the polyamide polyamine-epichlorohydrin resin by the above-described method, it may be added at the beginning or during the synthesis, or may be added to the aqueous solution after synthesizing the polyamide polyamine-epichlorohydrin resin. However, since precipitation easily occurs with respect to aluminum salts, a polyamide polyamine-epichlorohydrin resin was synthesized, and the pH of the aqueous solution was adjusted to 2.0.
After adjusting to 5.0, a method of adding a predetermined amount is preferable.

The metal salt has a metal weight of 0.
It is used in an amount of 1 to 2.0% by weight. 0.1% by weight
If the amount is less, the stability of the aqueous resin solution of the final product decreases, and gelation occurs within several days when stored at, for example, 50 ° C. The amount of the metal is more preferably 0.2% by weight or more based on the solid content of the resin. On the other hand, if the amount of the metal is more than 2.0% by weight, precipitation tends to occur in the aqueous resin solution of the product, which is problematic in terms of toxicity. It is advantageous from the viewpoint of toxicity that the metal salt is present such that the weight of the metal is 1.0% by weight or less based on the solid content of the resin, and sufficient stability can be obtained even in this case.

In the present invention, the pH of the aqueous resin solution is adjusted to 2.0 to 5.0, preferably 2.5 to 4.5. The pH adjustment may be performed in the presence of a metal salt, or as described above, the pH may be adjusted before adding the metal salt, and then the metal salt may be added. It is necessary to add salt so that the pH of the aqueous resin solution falls within the above range. The pH is adjusted by adding an acid such as hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, and acetic acid. Here, if the pH of the aqueous resin solution is lower than 2.0, the effect of improving the wet paper strength of the final product decreases over time. Also pH
Exceeds 5.0, the stability of the aqueous resin solution of the final product is reduced. For example, when stored at 50 ° C., gelation occurs within a few days.

<Effect of the Invention> Although the resin concentration of the aqueous solution of a polyamide polyamine-epichlorohydrin resin stable to gelation obtained by the conventional method is at most about 25% by weight, the method of the present invention has excellent stability. And an aqueous solution of a polyamide polyamine-epichlorohydrin resin having a high resin concentration of 30% by weight or more. Furthermore, since the amount of the metal salt to be added is small, there is no precipitation due to aging, and the problem of toxicity can be solved. The aqueous resin solution obtained according to the present invention exhibits the same wet paper strength improving effect as that of the aqueous polyamide polyamine-epichlorohydrin resin solution produced by the conventional method.

<Examples> Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
The percentages in the examples are on a weight basis.

Example 1 138.7 g (0.95 mol) of adipic acid, 103 g (1.0 mol) of diethylenetriamine, 10 g of water and 3 g (0.022 mol) of 71% sulfuric acid were charged and reacted at 160 to 165 ° C. for 19 hours while removing water. Thereafter, 206 g of water was gradually added to obtain a polyamide polyamine aqueous solution. It has a solid content of 50.2% and 25 ° C
Was 530 cps. Next, the total amount of the polyamide polyamine aqueous solution was diluted with 458.5 g of water, and 148 g (1.6 mol) of epichlorohydrin was added dropwise at 20 ° C. over 15 minutes. Then, the temperature was raised to 40 ° C., and the mixture was stirred at the same temperature for 3 hours. Thereafter, the temperature was raised to 60 ° C to increase the viscosity, and the temperature of the reaction solution was 25 ° C.
When the viscosity at 280 cps reached pH 3.
It was adjusted to 5 to obtain a high-concentration polyamidepolyamine-epichlorohydrin resin aqueous solution. Thereafter, 171.8 g of water was added to dilute the solid content to 30%. Aluminum sulfate was added to the thus obtained aqueous solution of the polyamide polyamine-epichlorohydrin resin so that the aluminum weight was 0.2% based on the solid content of the resin. The pH of the aqueous resin solution after the addition of aluminum sulfate was 3.3. The polyamidepolyamine-epichlorohydrin resin aqueous solution thus obtained was stable for about one month or more without gelation in a temporal stability test at 50 ° C.

Example 2 The high-concentration polyamidoamine-epichlorohydrin resin aqueous solution (solid content: 35%) before dilution obtained in Example 1 was
Aluminum sulfate was added so that the aluminum weight was 0.2% based on the resin solids. The pH of the aqueous resin solution after the addition of aluminum sulfate was 3.3. The thus obtained high-concentration polyamidepolyamine-epichlorohydrin resin aqueous solution was stable for about one month or more without gelation in a temporal stability test at 50 ° C.

Example 3 138.7 g (0.95 mol) of adipic acid, 103 g (1.0 mol) of diethylenetriamine, 10 g of water and 3 g (0.022 mol) of 71% sulfuric acid were charged and reacted at 160 to 165 ° C. for 19 hours while removing water. Thereafter, 206 g of water was gradually added to obtain a polyamide polyamine aqueous solution. It has a solid content of 50.2% and 25 ° C
Was 530 cps. Next, the total amount of the polyamidepolyamine aqueous solution was diluted with 329.8 g of water, and 148 g (1.6 mol) of spikychlorhydrin was added dropwise at 20 ° C. over 15 minutes. Then, the temperature was raised to 40 ° C., and the mixture was stirred at the same temperature for 3 hours. Thereafter, the temperature was raised to 60 ° C to increase the viscosity, and the temperature of the reaction solution was 25 ° C.
When the viscosity at 280 cps reached pH 3.
It was adjusted to 5 to obtain a high-concentration polyamidepolyamine-epichlorohydrin resin aqueous solution (solid content: 40%). Aluminum sulfate was added to the thus obtained aqueous solution of the polyamide polyamine-epichlorohydrin resin so that the aluminum weight was 0.7% based on the resin solid content. The pH of the aqueous resin solution after the addition of aluminum sulfate was 3.3.
The thus obtained high-concentration polyamide polyamine-
The aqueous epichlorohydrin resin solution was stable for about one month or more without gelation in a temporal stability test at 50 ° C.

Example 4 Highly concentrated aqueous solution of polyamide polyamine-epichlorohydrin resin before dilution obtained in Example 1 (solid dark 35%)
Copper sulfate was added to the mixture so that the copper weight was 0.2% based on the solid content of the resin. The pH of the aqueous resin solution after the addition of copper sulfate was 3.3. The thus obtained high-concentration polyamidepolyamine-epichlorohydrin resin aqueous solution was stable for about one month or more without gelation in a temporal stability test at 50 ° C.

Comparative Example 1 A high-concentration polyamidepolyamine-epichlorohydrin resin aqueous solution (solid content 35%) before dilution obtained in Example 1
Iron chloride was added so that iron weight was 44% based on resin solids. The pH of the aqueous resin solution after the addition of iron chloride was 3.3. The high-concentration polyamide polyamine-epichlorohydrin resin aqueous solution obtained in this manner did not gel for several months in the stability test at 50 ° C., but after one week, the entire resin aqueous solution turned yellow-brown,
A large amount of insoluble matter such as iron rust was formed on the liquid surface, and the resin form was remarkably deteriorated, making it unusable for use.

Comparative Example 2 High-concentration polyamide polyamine-epichlorohydrin resin aqueous solution (solid content 35%) before dilution obtained in Example 1
Calcium chloride was added so that the weight of calcium was 1% based on the solid content of the resin. The pH of the aqueous resin solution after the addition of calcium chloride was 3.3. The high-concentration polyamide polyamine-epichlorohydrin resin aqueous solution obtained in this manner showed a stability of 6
Gelled in days.

Example 3 High-concentration polyamide polyamine-epichlorohydrin resin aqueous solution (solid content 35%) before dilution obtained in Example 1
Then, zinc sulfate was added so that the zinc weight was 1% based on the resin solid content. The pH of the aqueous resin solution after adding zinc sulfate is 3.
Was 3. The high-concentration polyamide polyamine-epichlorohydrin resin aqueous solution thus obtained gelled in two days in a stability test at 50 ° C. over time.

Claims (1)

(57) [Claims] An aliphatic dicarboxylic acid having a molar ratio of 1: 1.0 to 1.2 and a polyalkylene polyamine are prepared by mixing a 50% by weight aqueous solution of the resulting polyamide polyamine at 25 ° C. with a viscosity of 400 to 1
The reaction was carried out so as to be 000 cps. The obtained polyamide polyamine was reacted with epichlorohydrin 1.6 to 1.7 mole times the amount of the secondary amino group in the obtained polyamide polyamine and the polyamide polyamine at a viscosity of 25 to 30% by weight of an aqueous solution of the product at 150 ° C. The resulting polyamide polyamine-epichlorohydrin resin aqueous solution is reacted with a metal salt selected from the group consisting of aluminum, copper and nickel, and the weight of the metal in the metal salt is 0.1 to 2.0% by weight
A method for producing an aqueous solution of a cationic thermosetting resin having a resin concentration of 30% by weight or more, wherein the pH of the aqueous resin solution is adjusted to 2.0 to 5.0.