KR20040036298A - Process for preparing a pure melamine Derivative - Google Patents

Abstract

PURPOSE: A process for preparing high purity melamine derivatives are provided, thereby preparing melamine derivatives through one-step process, significantly reducing the amount of salts and ions prepared as by-products, and producing no unreacted formaldehyde because formaldehyde is not used in the process, so that purity of melamine derivatives can be improved. CONSTITUTION: A process for preparing high purity melamine derivatives represented by the formula(3) comprises the steps of: directly reacting melamine of the formula(1) with haloalkyl alkyl ether of the formula(2) of R¬7-O-R¬8-X at pH 10 to 13 regulated by alkali reaction catalyst and 20 to 70 deg. C; adding a neutralizing agent into the reaction product to regulate pH to 6.0 to 8.0; distilling the product to remove water and unreacted haloalkyl alkyl ether; and stirring the product containing solution with an adsorbing agent at 80 to 150 deg. C for 1 to 5 hours and filtering the solution to remove salts and ions, wherein X is halogen atom; R1, R2, R3, R4, R5 and R6 are the same or different, hydrogen or R8OR7, except that all of them are hydrogen simultaneously; R7 is hydrogen or C1 to C6 alkyl; and R8 is C1 to C4 alkylene.

Description

Process for preparing a pure melamine Derivative

The present invention relates to a method for producing a high purity melamine derivative, and more particularly, instead of the conventional production method for synthesizing the melamine derivative by a two-stage reaction of methylolation and methoxylation using melamine and formaldehyde as raw materials, A novel process for the preparation of melamine derivatives, which consists of a one-step reaction process in which a melamine and a haloalkyl alkyl ether are directly reacted to alkoxy alkylate.As in the conventional method, a large amount of salts, ions and unreacted formaldehyde remain in the reactants after the reaction is completed. There is no concern that the final target material to be obtained can be selectively and purely synthesized, and the manufacturing process is relatively simple and relates to a method for preparing melamine derivatives which is particularly useful for commercial applications.

Melamine derivatives are generally used as crosslinking agents in the manufacture of industrial products including paints, coatings, adhesives, tires, etc. because of their excellent crosslinking ability, mechanical and chemical properties and heat resistance. These melamine derivatives are generally transparent liquids, but may have a pale-white turbidity depending on the degree of methylolation and methoxylation, or may be mixed with white carbon and used in powder form depending on the intended use.

The crosslinking reaction of the melamine derivative proceeds as the alcohol is released by the transesterification reaction with the alcohols. Therefore, since the crosslinking reaction of melamine releases a low-volatile alcohol having high volatility, the crosslinking reaction occurs even at low temperature when used in thermosetting paint, the drying speed is high, and the solubility in paint solvent is also excellent.

The general production method for synthesizing melamine derivatives consists of a two-step reaction consisting of a methylolation process in which melamine and formaldehyde are reacted under alkaline or neutral conditions and a methoxylation process in which the prepared methylol melamine and methanol are reacted under acidic conditions. . The methylolation reaction is a condensation reaction between melamine and formaldehyde, which occurs as a nucleophilic bond between the amine group in the melamine molecule and the carbon atom in the formaldehyde molecule, and the methoxylation reaction introduces a large amount of acidic catalyst by transesterification reaction between methylol melamine and methanol. By an acidic atmosphere of pH 3 or less. Therefore, the conventional method for preparing a melamine derivative is complicated and it is impossible to synthesize purely the target substance to be finally obtained purely, and after the reaction is completed, a large amount of salts and ions are present in the reactants. However, since formaldehyde is used as a raw material for the production of melamine, unreacted formaldehyde remains in the product after the reaction is completed, and the problem that the unreacted formaldehyde is released when the crosslinking reaction proceeds to solve the problem. Many researches are being conducted intensively.

Regarding the method for preparing a melamine derivative, the following technique is known.

U.S. Patent No. 3,487,048 discloses a method in which the ratio of melamine and formaldehyde is 1: 3 to 6 to react under an acid catalyst, and then neutralized with alkali to obtain a product having an unreacted formaldehyde content of less than 16% by weight. Known.

In U.S. Patent No. 4,183,832, melamine and formaldehyde are reacted in an alkaline atmosphere of pH 8.5 to 9.5 to synthesize methoxymethylmelamine having a low content of unreacted formaldehyde used as a binder in glass fiber mats. Methylol melamine is synthesized, which is then subjected to methoxylation with methanol under an acidic atmosphere, and then neutralized with triethanolamine, and unreacted formaldehyde is removed by reacting with urea to remove unreacted formaldehyde content. It is known to obtain melamine derivatives of less than 6% by weight. However, when synthesized in this way, the amount of salts and ions increases in the final product and impurities such as urea-formaldehyde condensate are generated.

U.S. Patent No. 3,488,350 provides a method of proceeding a methoxylation reaction using a cation exchange resin, which is completely separated from the methylolation reaction and the methoxylation reaction, making continuous production of the product difficult and dehydrating and washing the cation exchange resin. There is a problem that must be recovered.

In US Pat. No. 3,322,762, high purity products were synthesized by adding methanol twice in the methylolation and methoxylation processes. In the methylolation process, formaldehyde is used as paraformaldehyde. In this case, methanol used in the methoxylation process is pre-injected to facilitate stirring of the reactants. However, methanol is known as a substance that interferes with the methylolation reaction. Therefore, if the reaction is carried out by adding only a minimum amount to facilitate stirring without adding the entire amount of methanol, high-purity methoxymethylmelamine having a high content of hexamethoxymethylmelamine is obtained. Can be synthesized. However, even in this case, since the alkaline catalyst is used in the methylolation process, a large amount of salts and ions are generated.

U.S. Patent No. 4,433,143 provides that the reaction ratio of melamine and formaldehyde is 1: 3 to 5 and is reacted under an alkaline atmosphere of pH 8-9.

In addition, in US Pat. No. 5,821,323, the reaction ratio of melamine and formaldehyde is 1: 2.6 to 4.6, and the reaction is carried out in an alkaline atmosphere of pH 8, and the content of unreacted formaldehyde is less than 0.5% by weight, and the content of N-substituted methylol is 6.0. It is known to prepare a methoxymethylmelamine crosslinking agent which is less than% by weight.

However, the conventional manufacturing methods as described above are complicated by the reaction in two stages, and it is impossible to selectively synthesize purely the target substance to be finally obtained. The final product is directly used by using formaldehyde during the reaction. There is a problem that a large amount of unreacted formaldehyde is detected in the bar, an effort to solve this problem is required.

The present invention has been made to solve the problems of the conventional manufacturing method as described above, by directly reacting haloalkyl alkyl ether and melamine under alkaline conditions, it is possible to directly synthesize a high purity melamine derivative, the amount of salt and ions produced A novel method for the preparation of high purity melamine derivatives, which not only significantly reduces the efficiencies but also improves their removal efficiency and does not detect any unreacted formaldehyde at all by not directly using formaldehyde during the reaction. The purpose is to provide.

The present invention is characterized by a method for producing a melamine derivative represented by the following formula (3) by directly reacting the melamine represented by the formula (1) and the haloalkyl alkyl ether represented by the following formula (2).

In the above formula, 나타내고 represents a halogen atom, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are the same or different and represent a hydrogen atom or -R ⁸ OR ⁷ , provided that Except for the case, R ⁷ represents a hydrogen atom or an alkyl group of C _{1 to} C ₆ , and R ⁸ represents an alkylene group of C ₁ to C ₄ .

Referring to the present invention in more detail as follows.

The method for preparing a melamine derivative according to the present invention is composed of one step of an alkoxy alkylation reaction in which a melamine and a haloalkyl alkyl ether are directly reacted instead of performing a conventional two-stage reaction, and do not use formaldehyde as a reaction material. An improved process for the preparation of melamine derivatives with no concern for residual residual formaldehyde.

Further subdividing the process for preparing melamine derivatives according to the invention is as follows: alkoxy alkylation reaction step of directly reacting haloalkyl alkyl ether and melamine under alkaline conditions; Neutralizing by injecting a neutralizing agent into the reactant; Distilling off and recovering water and unreacted haloalkyl alkyl ethers in the reactants; Adsorbing and removing salts and ions remaining in the reactants by the above step.

In the alkoxy alkylation reaction of the present invention, the alkali metal or alkaline earth metal hydroxides, oxides, alkoxides, and the like are used under alkaline conditions as reaction promoters. Specifically, the reaction accelerator uses one or two or more selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium oxide, magnesium hydroxide, sodium methoxylate, sodium ethoxylated, potassium methoxylated and potassium ethoxylated.

The melamine and haloalkyl alkyl ether used in the raw material of the present invention are reacted in the range of 1: 2 to 30 molar ratio, preferably 1: 3 to 12 molar ratio. In addition, the reaction accelerator used in the alkoxy alkylation reaction is added in a range of 2 to 20 molar ratios, preferably 3 to 10 molar ratios per 1 mole of melamine to adjust the pH to 10 to 13 and proceed with the alkoxy alkylation reaction at 20 to 70 ° C. do.

After the alkoxy alkylation reaction is completed, the pH of the reaction is neutralized by injecting at least one neutralizing agent selected from the group consisting of formic acid, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, perchloric acid and nitrous acid.

When neutralization is complete, water and unreacted haloalkyl alkyl ethers in the reactants are removed by distillation.

The adsorbent was added to the reaction product from which water and unreacted haloalkyl alkyl ether were removed, and then stirred at 80 to 150 ° C. for 1 to 5 hours, followed by filtration, thereby obtaining a melamine derivative from which salts and ions were completely removed. The adsorbent may be selected from silicate salts and sulfate salts of alkaline earth metals. Specifically, at least one selected from the group consisting of magnesium silicate, magnesium sulfate, calcium silicate and calcium sulfate may be used. The adsorbent is used in the range of 0.1 to 10% by weight relative to the crude final target.

As described above, the method for preparing the melamine derivative according to the present invention must be an improved method, in which the process is relatively simple and there is no fear of remaining of salts, ions, and fatal unreacted substances after the reaction is completed.

Hereinafter, the present invention will be described in more detail based on the following examples, the present invention is not limited to these examples, and those skilled in the art to which the present invention pertains without departing from the scope of the claims. Various modifications may be made without departing from the scope of the invention.

Example 1

1 mole (126.12 g) of melamine and 7 mole (933.27 g) of 30% aqueous sodium hydroxide solution were added to a four-necked reactor equipped with a thermometer, agitator, and reflux, and stirred. 9 mole (724.62) of chloromethyl methyl ether (CMME) at room temperature. g) was slowly added dropwise over 30 minutes, and then the temperature was raised to 60 ° C. and reacted for 3 hours. After the reaction, the mixture was cooled to room temperature, neutralized to pH 7.0 with 10% aqueous hydrochloric acid solution, and water and unreacted chloromethyl methyl ether were removed by distillation and recovered. 0.2 wt% magnesium silicate of the remaining product was added to the remaining product, stirred at 110 ° C. for 3 hours, and vacuum filtered to obtain 0.98 mole (382.63 g; yield 98%) of a colorless transparent liquid product.

HPLC analysis showed that the final product was hexamethoxymethylmelamine (HMMM) 99.0%, pentamethoxymethylmelamine (PMMM) 0.6%, butamethoxymethylmelamine (BMMM) and other low molecular weight 0.4%, dimer and high molecular weight The content of 0%, moisture and residual formaldehyde was 0%.

Examples 2-4

Melamine derivatives were synthesized under the same reaction and post-treatment conditions as in Example 1, except that only the amount of chloromethyl methyl ether (CMME) added to melamine was changed. As a result, the yield and content of residual components in the product are shown in Table 1 below.

division Reaction ratio (molar ratio) yield(%) % Of ingredient in final product Melamine CMME HMMM PMMM BMMM and others Dimers and High Molecular Weight Materials Moisture and formaldehyde Example 1 One 9 98 99.0 0.6 0.4 0.0 0.0 Example 2 One 7 90 94.0 4.5 1.5 0.0 0.0 Example 3 One 8 95 97.0 2.2 0.8 0.0 0.0 Example 4 One 10 98 99.0 0.7 0.3 0.0 0.0

Examples 5-14

Melamine derivatives were synthesized under the same reaction and post-treatment conditions as in Example 1, but only the type and amount of the reaction promoter were changed. As a result, the yield and content of residual components in the product are shown in Table 2 below.

division Reaction ratio (molar ratio) yield(%) % Of ingredient in final product Melamine CMME HMMM PMMM BMMM and others Dimers and High Molecular Weight Materials Moisture and formaldehyde Example 5 One KOH (7) 98 99.0 0.7 0.3 0.0 0.0 Example 6 One MgO (7) 95 96.5 2.5 1.0 0.0 0.0 Example 7 One Mg (OH) ₂ (7) 94 95.5 3.0 1.5 0.0 0.0 Example 8 One NaOH (5) 98 99.0 0.5 0.5 0.0 0.0 Example 9 One NaOH (5) 98 99.0 0.6 0.4 0.0 0.0 Example 10 One NaOH (5) KOMe (2) 98 99.0 0.6 0.4 0.0 0.0 Example 11 One NaOH (5) KOEt (2) 98 99.0 0.6 0.4 0.0 0.0 Example 12 One NaOH (6) 94 95.7 2.9 1.4 0.0 0.0 Example 13 One NaOH (8) 98 99.0 0.5 0.5 0.0 0.0

Comparative example

Into a four-necked reactor equipped with a thermometer, agitator, and reflux, 1 mole of melamine, 20 mole of paraformaldehyde, 60 mole of methanol, and 0.4% by weight of 50% aqueous sodium hydroxide solution were heated up to 70 ° C until a completely transparent phase was obtained at pH 8.5. The reaction was carried out for 90 minutes. The reactor gradually changed from a transparent phase to a pale white cloudy phase, where formic acid was added 1.5% by weight to adjust the pH to 3.4 and reacted at 70 ° C. for 14 hours. The solution was neutralized with 50% aqueous sodium hydroxide solution to pH 7.0. The solution was passed through a thin film distillation apparatus under conditions of a temperature of 120 ° C., a pressure of 50 torr, a rotational speed of 300 rpm, and a flow rate of 1.0 L / hour. To remove salts and ions of the reactants separated by the thin film distillation apparatus, 2 wt% of magnesium silicate was purified and stirred at 110 ° C. for 3 hours, followed by vacuum filtration to obtain a colorless transparent liquid product.

HPLC analysis showed that the final product was HMMM 24.9%, PMMM 18.9%, BMMM and other 12.6%, dimer and high molecular weight material 38.1%, unreacted formaldehyde 2.2%, water 3.3%.

Comparative Example 2

1 mole of melamine, 20 mole of paraformaldehyde, 60 mole of methanol and 0.01 mole of zinc acetate were added to a 4-necked reactor equipped with a thermometer, a stirrer, and a refluxing device, and the reaction was performed for 70 minutes until the temperature became completely transparent at pH 6.9. I was. The reactor gradually changed from a transparent phase to a pale white cloudy phase, and formic acid was added thereto to adjust the pH to 3.4, followed by reaction at 70 ° C. for 14 hours. The solution was neutralized with 50% aqueous sodium hydroxide solution to pH 7.0. The solution was passed through a thin film midstream under conditions of a temperature of 120 ° C., a pressure of 50 torr, a rotational speed of 300 rpm, and a flow rate of 1.0 L / hour. To remove salts and ions of the reactants separated by the thin film distillation apparatus, 2 wt% of magnesium silicate was purified and stirred at 110 ° C. for 3 hours, followed by vacuum filtration to obtain a colorless transparent liquid product.

HPLC analysis showed that the final products, HMMM 26.0%, PMMM 17.2%, BMMM and other 11.5%, dimer and high molecular weight material 41.0%, unreacted formaldehyde 1.5%, water 2.8%.

The present invention is capable of synthesizing melamine derivatives by one step reaction of alkoxy alkylation reaction which directly reacts haloalkyl alkyl ether and melamine under alkaline conditions, and dramatically reduces the amount of salts and ions generated after the reaction is completed. It was possible not only to improve the removal efficiency, but also to selectively synthesize purely hexamethoxymethylmelamine, which is the target substance to be finally obtained, and by not using formaldehyde directly during the reaction, unreacted formaldehyde It is not detected at all and has the advantage of high purity of the product by effectively removing the unreacted material.

Claims (7)

A method for preparing a melamine derivative represented by the following Chemical Formula 3, which is prepared by reacting melamine represented by the following Chemical Formula 1 with a haloalkyl alkyl ether represented by the following Chemical Formula 2. [Formula 1] [Formula 2] [Formula 3] In the above formula, 나타내고 represents a halogen atom, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are the same or different and represent a hydrogen atom or -R ⁸ OR ⁷ , provided that Except for the case, R ⁷ represents a hydrogen atom or an alkyl group of C _{1 to} C ₆ , and R ⁸ represents an alkylene group of C ₁ to C ₄ . The method for producing a melamine derivative according to claim 1, wherein the haloalkyl alkyl ether represented by the formula (2) is used in a range of 2 to 30 molar ratio with respect to 1 mole of the melamine. The alkoxy alkylation reaction according to claim 1, wherein the alkaline reaction promoter is added to adjust the pH to 10 to 13, and the melamine represented by the formula (1) and the haloalkyl alkyl ether represented by the formula (2) are reacted directly at 20 to 70 ° C. Proceeding with; Injecting a neutralizing agent to neutralize the pH to 6.0 to 8.0; Distilling off and recovering water and unreacted haloalkyl alkyl ethers; Method for producing a melamine derivative characterized in that it comprises a step of adsorbing and removing salts and ions contained in the reaction product after stirring for 1 hour to 5 hours at 80 ~ 150 ℃ using an adsorbent. 4. The alkaline reaction accelerator according to claim 3, wherein one or two or more selected from the group consisting of hydroxides, oxides and alkoxides of alkali metals or alkaline earth metals is used as the alkaline reaction promoter, and 2 to 20 moles are used for 1 mole of melamine. Method for producing a melamine derivative, characterized in that. The method according to claim 4, wherein the alkaline reaction accelerator is selected from the group consisting of sodium hydroxide, potassium hydroxide, magnesium oxide, magnesium hydroxide, sodium methoxylate, sodium ethoxylated, potassium methoxylated, and potassium ethoxylated Method for producing a melamine derivative, characterized in that the mixed use. 4. The method for producing a melamine derivative according to claim 3, wherein at least one selected from the group consisting of formic acid, acetic acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, perchloric acid and nitrous acid is used as the neutralizing agent. 4. The melamine derivative according to claim 3, wherein at least one adsorbent selected from the group consisting of magnesium silicate, magnesium sulfate, calcium silicate and calcium sulfate is used in an amount of 0.1 to 10% by weight relative to the crude final target. Manufacturing method.