JPH09309856A - Aqueous solution of formaldehyde - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous solution of formaldehyde capable of manifesting remarkable stabilizing effects in spite of a small amount of an added specific stabilizer and sustaining the effects thereof for a long period by adding the stabilizer to an aqueous solution of the formaldehyde. SOLUTION: This aqueous solution of formaldehyde is obtained by adding an organic mono- or a polycarboxylic acid of the formula R-COOH (R is a 2-10C aliphatic hydrocarbon residue having at least one substituent group selected from OH, amino, carboxyl, imidazolyl and carbamoyl or a 6-12C cyclic hydrocarbon residue or a nitrogen-containing 6-membered heterocyclic residue which may be substituted with OH, COOH, etc.) to an aqueous solution of the formaldehyde. Glycine, alanine, benzoic acid, malonic acid, lactic acid, aspartic acid, serine, phenylalanine, phthalic acid, malic acid, salicylic acid, malonic acid monoamide, etc., are cited as the organic mono- or polycarboxylic acid. The amount of the added organic mono- or polycarboxylic acid is 0.0001-0.1mol based on 1mol formaldehyde.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aqueous formaldehyde solution. More specifically, the present invention relates to an aqueous formaldehyde solution in which turbidity or precipitate formation during storage is prevented.

[0002]

Formaldehyde is generally 37% by weight.
Is commercially available as an aqueous formaldehyde solution. This formaldehyde is predominantly hydrated in aqueous solution and exists as an equilibrium mixture of methylene glycol and lower polyoxymethylene glycol. This equilibrium moves to the higher polymerization side as the formaldehyde concentration increases,
The high degree of polymerization component precipitates as paraformaldehyde insoluble in water. The precipitation of paraformaldehyde causes turbidity or precipitation of the aqueous formaldehyde solution, and in the extreme case, the entire aqueous solution may solidify. In addition, as the temperature of the formaldehyde aqueous solution becomes lower, the solubility of polyoxymethylene glycol decreases, and the paraformaldehyde precipitates. Thus, the aqueous formaldehyde solution has poor stability and its handling is very difficult. In addition, this turbidity or precipitation causes blockage of the device, piping and the like. Further, in recent years, 40 to 50% by weight of high-concentration formaldehyde aqueous solution has been industrially used, and there is an urgent need for solving the above problems.

Therefore, in order to prevent the precipitation of paraformaldehyde during the storage of such formaldehyde aqueous solution, a method of increasing the methanol content in the formaldehyde aqueous solution and the storage temperature and adding various additives is disclosed. (JP-B-57-61009, JP-B-62-41593, JP-A-4-330030, JP-A-4-330031, JP-B-8-2824, JP-B-8-28)
(See Japanese Patent No. 25).

[0004]

In recent years, aqueous solution of formaldehyde has been economically used due to the pursuit of cost reduction, or due to use reasons such as shortened reaction time in resin synthesis or reduction of industrial wastewater treatment load. It is desired to reduce the methanol content rate. In order to stabilize the low methanol content formaldehyde aqueous solution, it is necessary to increase the amount of the stabilizer added and to increase the storage temperature. However, when the storage temperature is increased, the Cannizzaro reaction produces formic acid, which causes a corrosion problem.

[0005]

SUMMARY OF THE INVENTION The inventors of the present invention have
As a result of diligent research to obtain a stable aqueous formaldehyde solution, a remarkable stabilizing effect despite the low addition amount, that is, it is not necessary to raise the storage temperature even if the methanol content is low, and the stabilizing effect is sustained. The present invention was completed by finding a stabilizer obtained by the above.

Thus, according to the present invention, the aqueous formaldehyde solution has the general formula (I): R-COOH (I) (wherein R is at least a hydroxyl group, an amino group, a carboxyl group, an imidazolyl group and a carbamoyl group). An aliphatic hydrocarbon residue having 2 to 10 carbon atoms having one substituent, or 6 to 12 carbon atoms optionally having at least one substituent selected from a hydroxyl group, an amino group and a carboxyl group. A stable formaldehyde aqueous solution obtained by adding an organic mono- or polycarboxylic acid represented by the cyclic hydrocarbon residue or the nitrogen-containing 6-membered heterocyclic residue of

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The organic mono- or polycarboxylic acid of the general formula (I) added to the stable aqueous formaldehyde solution of the present invention is preferably an organic mono-, di- or tricarboxylic acid. In addition, in the formula, the aliphatic hydrocarbon residue represents a saturated or unsaturated, linear, branched, or cyclic aliphatic hydrocarbon residue.

Specific examples of the compound represented by the general formula (I) include glycine, glycylglycine, alanine and β-.
Amino acids such as alanine, valine, leucine, isoleucine and piperidic acid; cyclic carboxylic acids such as benzoic acid and nicotinic acid; dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid and maleic acid; glycolic acid, lactic acid, Oxyacids such as glyceric acid, α-oxybutyric acid and hydroacrylic acid; monoaminodicarboxylic acids such as aspartic acid and glutamic acid; oxyamino acids such as serine and threonine; phenylalanine, histidine, anthranilic acid and p-aminobenzoic acid Cyclic amino acids; phthalic acid and methyl-cyclohexene-
Cyclic dicarboxylic acids such as dicarboxylic acids; oxydicarboxylic acids such as malic acid, tartaric acid and citric acid; cyclic oxyacids such as salicylic acid and mandelic acid; malonic acid monoamide, succinic acid monoamide, glutaric acid monoamide, adipic acid monoamide and maleic acid monoamide And other monoamidocarboxylic acids. Also, two or more of these compounds may be used in combination.

Among the above compounds, glycylglycine, alanine, β-alanine, benzoic acid, nicotinic acid, glutaric acid, glycolic acid, lactic acid, aspartic acid, glutamic acid, serine, phenylalanine, phthalic acid, methyl-
Cyclohexene-dicarboxylic acid, malic acid, salicylic acid, maleic acid and maleic acid monoamide are preferred,
Glycolic acid and glycylglycine are more preferred.

The addition amount (effective addition amount) of the organic mono- or polycarboxylic acid of the present invention necessary for suppressing the turbidity or precipitation of the formaldehyde aqueous solution can be appropriately determined depending on the concentration, pH and temperature of the formaldehyde aqueous solution. it can. For example, the aqueous formaldehyde solution tends to be stable as the concentration becomes lower, the pH becomes lower, and the temperature becomes higher. Therefore, if the stability is high, the addition amount of the organic mono- or polycarboxylic acid can be further reduced. Generally, the addition amount of the organic mono- or polycarboxylic acid can be 0.0001 to 0.1 mol, preferably 0.001 to 0.01 mol, relative to 1 mol of formaldehyde. When the amount added is within the above range, the organic mono- or polycarboxylic acid is easily dissolved in the aqueous formaldehyde solution, and a sufficient stabilizing effect can be obtained.

The aqueous formaldehyde solution to which the organic mono- or polycarboxylic acid of the present invention is added may contain a compound such as methylal, methanol, dimethyl ether, formic acid, methyl formate, or trioxane depending on the origin of the formaldehyde or the production process. It doesn't matter.

[0012]

The present invention is illustrated by the following formulation examples and test examples, but these exemplifications do not limit the scope of the present invention. Formulation Example 1 50 wt% formaldehyde aqueous solution 99.9 parts by weight β-alanine 0.1 part by weight Formulation Example 2 50 wt% formaldehyde aqueous solution 99.9 parts by weight Benzoic acid 0.1 part by weight Formulation Example 3 50 wt% formaldehyde aqueous solution 99 9.9 parts by weight Nicotinic acid 0.1 parts by weight Formulation example 4 50% by weight aqueous formaldehyde solution 99.9 parts by weight Glycolic acid 0.1 parts by weight Formulation example 5 50% by weight aqueous formaldehyde solution 99.9 parts by weight Aspartic acid 0.1 parts by weight Department

Formulation Example 6 50% by weight formaldehyde aqueous solution 99.9 parts by weight Methyl-cyclohexene-dicarboxylic acid 0.1 parts by weight Formulation Example 7 50% by weight formaldehyde aqueous solution 99.9 parts by weight Maleic acid 0.1 parts by weight Formulation Example 8 50 wt% formaldehyde aqueous solution 99.9 parts by weight Maleic acid monoamide 0.1 part by weight Formulation example 9 50% by weight formaldehyde aqueous solution 99.9 parts by weight Glycylglycine 0.1 part by weight Formulation example 10 50% by weight formaldehyde aqueous solution 98.9 Parts by weight alanine 0.1 parts by weight methanol 1.0 parts by weight

Formulation Example 11 50 wt% formaldehyde aqueous solution 98.9 parts by weight Nicotinic acid 0.1 part by weight Methanol 1.0 part by weight Formulation Example 12 50% by weight formaldehyde aqueous solution 98.9 parts by weight Glutaric acid 0.1 part by weight Methanol 1.0 parts by weight Formulation Example 13 50% by weight aqueous formaldehyde solution 98.9 parts by weight Lactic acid 0.1 parts by weight Methanol 1.0 parts by weight Formulation Example 14 50% by weight aqueous formaldehyde solution 98.9 parts by weight Glutamic acid 0.1 parts by weight methanol 1.0 parts by weight Formulation Example 15 50% by weight aqueous formaldehyde solution 98.9 parts by weight Serine 0.1 parts by weight Methanol 1.0 parts by weight

Formulation Example 16 50 wt% formaldehyde aqueous solution 98.9 parts by weight Phenylalanine 0.1 part by weight methanol 1.0 part by weight Formulation Example 17 50% by weight formaldehyde aqueous solution 98.9 parts by weight phthalic acid 0.1 part by weight methanol 1 0.0 parts by weight Formulation Example 18 50% by weight aqueous formaldehyde solution 98.9 parts by weight Malic acid 0.1 parts by weight Methanol 1.0 parts by weight Formulation Example 19 50% by weight aqueous formaldehyde solution 98.9 parts by weight Salicylic acid 0.1 parts by weight methanol 1.0 parts by weight Formulation Example 20 50% by weight aqueous formaldehyde solution 94.9 parts by weight Nicotinic acid 0.09 parts by weight Phenylalanine 0.01 parts by weight Methanol 5.0 parts by weight

Comparative formulation example 1 50% by weight aqueous formaldehyde solution 99.0 parts by weight methanol 1.0 part by weight Comparative formulation example 2 50% by weight aqueous formaldehyde solution 95.0 parts by weight Methanol 5.0 parts by weight Comparative formulation example 3 50% by weight Aqueous formaldehyde solution 99.9 parts by weight Ethylene glycol 0.1 part by weight Comparative formulation example 4 50% by weight formaldehyde aqueous solution 99.9 parts by weight Triethylene glycol 0.1 part by weight Comparative formulation example 5 50% by weight formaldehyde aqueous solution 99.9 parts by weight Propionamide 0.1 part by weight

Comparative Formulation Example 6 50% by weight aqueous formaldehyde solution 99.9 parts by weight Succinamic acid 0.1 parts by weight Comparative formulation example 7 50% by weight aqueous formaldehyde solution 99.9 parts by weight Dimethyl glutarate 0.1 parts by weight Comparative formulation example 8 50 wt% formaldehyde aqueous solution 99.9 parts by weight acetylacetone 0.1 part by weight Comparative formulation example 9 50% by weight aqueous formaldehyde solution 98.9 parts by weight acetylacetone 0.1 part by weight methanol 1.0 part by weight Comparative formulation example 10 50% by weight formaldehyde Aqueous solution 98.9 parts by weight Propionic acid 0.1 parts by weight Methanol 1.0 parts by weight

Comparative formulation example 11 50% by weight formaldehyde aqueous solution 98.9 parts by weight sorbic acid 0.1 part by weight methanol 1.0 part by weight Comparative formulation example 12 50% by weight formaldehyde aqueous solution 98.9 parts by weight oleic acid 0.1 part by weight Parts Methanol 1.0 parts by weight Comparative Preparation Example 13 50% by weight aqueous formaldehyde solution 98.9 parts by weight Dimethyl glutarate 0.1 parts by weight Methanol 1.0 parts by weight Comparative Preparation Example 14 50% by weight aqueous formaldehyde solution 98.9 parts by weight Succinamide Acid 0.1 parts by weight Methanol 1.0 parts by weight Comparative Preparation Example 15 50% by weight aqueous formaldehyde solution 98.9 parts by weight Ethylene glycol 0.1 parts by weight Methanol 1.0 parts by weight

Test Example 1 [Stability Confirmation Test of 50% by Weight Formaldehyde Aqueous Solution at 50 ° C.] With respect to the formaldehyde aqueous solution formulations of Formulation Examples 1 to 9 and Comparative Formulation Examples 1 to 8, stability at 50 ° C. was measured every several days. confirmed. The evaluation criteria are defined as follows. ◯: No precipitate in the formaldehyde aqueous solution Δ: Slight turbidity of the formaldehyde aqueous solution ×: Formation of precipitate in the formaldehyde aqueous solution The results are shown in Table 1.

[0020]

[Table 1]

It can be seen from Table 1 that the addition of the organic mono- or polycarboxylic acid is effective in stabilizing the aqueous formaldehyde solution.

Test Example 2 [Stability Confirmation Test of 50% by Weight Formaldehyde Aqueous Solution at 50 ° C.] Formaldehyde aqueous solutions containing 1% of methanol (5% only in Formulation Example 19) of Formulation Examples 10 to 19 and Comparative Formulation Examples 9 to 15 The stability at 50 ° C was confirmed every several days. The evaluation criteria were the same as in Test Example 1. The results are shown in Table 2.
Shown in

[0023]

[Table 2]

It can be seen from Table 2 that the addition of the organic mono- or polycarboxylic acid is effective in stabilizing the aqueous formaldehyde solution containing a small amount of methanol.

Test Example 3 [Stability Confirmation Test by Concentration, pH and Temperature Change of Formaldehyde Aqueous Solution] Paraformaldehyde and water were mixed and stirred at 80 ° C. to obtain an aqueous formaldehyde solution having a predetermined concentration, and a small amount of sodium hydroxide was added to each. Or add hydrochloric acid
Adjusted to H. Then, this aqueous solution was cooled to a predetermined temperature to obtain a test sample. Β-Alanine as an organic mono- or polycarboxylic acid was added to the obtained test sample at each concentration, and the number of days required for precipitation or clouding was confirmed. Table 3 shows the results.

[0026]

[Table 3]

From Table 3, the lower the concentration of the formaldehyde aqueous solution, the lower the pH, and the higher the temperature, the more stable the aqueous solution is. Even if the addition amount of the organic mono- or polycarboxylic acid is small, the aqueous solution tends to be stable. It can be seen that is stabilized.

[0028]

EFFECTS OF THE INVENTION The present invention adds a stable and effective amount of organic mono- or polycarboxylic acid to an aqueous formaldehyde solution, so that the addition amount is small,
A stable formaldehyde aqueous solution can be provided by significantly suppressing turbidity or precipitation of the formaldehyde aqueous solution. In particular, it is possible to provide a formaldehyde aqueous solution that is more stable than a conventional formaldehyde aqueous solution to which additives are added and that is stable regardless of the storage temperature.

Claims (13)

[Claims] 1. An aqueous formaldehyde solution containing at least one substituent selected from the general formula (I): R—COOH (I) (wherein R is a hydroxyl group, an amino group, a carboxyl group, an imidazolyl group, and a carbamoyl group). An aliphatic hydrocarbon residue having 2 to 10 carbon atoms, or a cyclic hydrocarbon residue having 6 to 12 carbon atoms, which may optionally have at least one substituent selected from a hydroxyl group, an amino group and a carboxyl group. A stable formaldehyde aqueous solution obtained by adding an organic mono- or polycarboxylic acid represented by a group or a nitrogen-containing 6-membered heterocyclic residue). 2. The organic mono- or polycarboxylic acid of general formula (I) is glycine, glycylglycine, alanine, β-
The amino acid selected from at least one of alanine, valine, leucine, isoleucine and piberidic acid.
The aqueous solution described. 3. The aqueous solution according to claim 1, wherein the organic mono- or polycarboxylic acid of the general formula (I) is a cyclic carboxylic acid selected from one or more kinds of benzoic acid and nicotinic acid. 4. The aqueous solution according to claim 1, wherein the organic mono- or polycarboxylic acid of the general formula (I) is a dicarboxylic acid selected from at least one of malonic acid, succinic acid, glutaric acid, adipic acid and maleic acid. . 5. The organic mono- or polycarboxylic acid of general formula (I) is an oxy acid selected from one or more of glycolic acid, lactic acid, glyceric acid, α-oxybutyric acid and hydroacrylic acid. Aqueous solution. 6. The aqueous solution according to claim 1, wherein the organic mono- or polycarboxylic acid of the general formula (I) is a monoaminodicarboxylic acid selected from at least one of aspartic acid and glutamic acid. 7. The aqueous solution according to claim 1, wherein the organic mono- or polycarboxylic acid of the general formula (I) is an oxyamino acid selected from one or more kinds of serine and threonine. 8. The aqueous solution according to claim 1, wherein the organic mono- or polycarboxylic acid of the general formula (I) is a cyclic amino acid selected from one or more selected from phenylalanine, histidine, anthranilic acid and p-aminobenzoic acid. 9. The aqueous solution according to claim 1, wherein the organic mono- or polycarboxylic acid represented by the general formula (I) is a cyclic dicarboxylic acid selected from one or more of phthalic acid and methyl-cyclohexene-dicarboxylic acid. 10. The aqueous solution according to claim 1, wherein the organic mono- or polycarboxylic acid of the general formula (I) is an oxydicarboxylic acid selected from one or more kinds of malic acid, tartaric acid and citric acid. 11. The aqueous solution according to claim 1, wherein the organic mono- or polycarboxylic acid of the general formula (I) is a cyclic oxy acid selected from at least one of salicylic acid and mandelic acid. 12. The organic mono- or polycarboxylic acid of general formula (I) is malonic acid monoamide, succinic acid monoamide,
The aqueous solution according to claim 1, which is a monoamide carboxylic acid selected from one or more of glutaric acid monoamide, adipic acid monoamide and maleic acid monoamide. 13. The organic mono- or polycarboxylic acid represented by the general formula (I) is 0.000 with respect to 1 mol of formaldehyde.
The formaldehyde aqueous solution according to any one of claims 1 to 12, which is contained in an amount of 1 to 0.1 mol.