KR20120128004A - Dimethyl 2-methylenemalonate process - Google Patents

Abstract

PURPOSE: A manufacturing method of dimethyl 2-methylenemalonate is provided to manufacture dimethyl 2-methylenemalonate with high stability and low emitting amount of formaldehyde by hydrolysis, to have excellent solubility and thermal stability, and moderate hardness and flexibility. CONSTITUTION: A manufacturing method of dimethyl 2-methylenemalonate comprises a step of synthesizing a polymer through a condensation of formaldehyde and malonate, and conducting heat depolymerization in a vacuum state. When polymerizing, a solvent with a density lower than water and a boiling point of 74-177°C is used. The solvent is one selected from methyl isobutyl ketone, acetic acid and ethylacetate. The comprised amount of the solvent is 200-300 parts by weight based on 100.0 parts by weight of the formaldehyde and malonate. [Reference numerals] (AA) Estimated value 72g(0.5mol); (BB) Estimated value 9g(0.5mol)

Description

Method for producing dimethyl 2-methylenemalonate {Dimethyl 2-methylenemalonate process}

The present invention relates to a method for preparing dimethyl 2-methylenemalonate, and more particularly, has excellent solubility and thermal stability, has a predetermined hardness and appropriate flexibility, and has a high safety due to a small amount of formaldehyde emission due to hydrolysis. It relates to a process for preparing dimethyl 2-methylenemalonate.

Instant adhesive has fast adhesion speed and good bonding strength. Due to its properties such as ease of use, it is used in industrial and household applications such as bonding plastics, rubber, glass, metal, wood, and medical / surgical applications such as biological tissues, medical tissues, or living tissues. Among these instantaneous adhesives, cyanoacrylate-based instant adhesives are cyanoacrylates used as main components, which are electrophilic monomers having strong electron attraction.

Such cyanoacrylates are polymerized and cured even with moisture in the air or a small amount of moisture adhering to the surface of the material, and the curing time is known to be within 10 seconds. Thickeners, plasticizers, and colorants are used to increase the performance of the adhesive. It is suitably mixed and used with a preservative, a heat dissipating agent, and a stabilizer.

Such cyanoacrylates are generally prepared by obtaining polymers by Knoevenagel condensation reactions between formaldehyde precursors such as paraformaldehyde and alkyl cyanoacetates using basic catalysts, and depolymerization under high temperature and reduced pressure. Adhesion performance and curing properties vary depending on the type of alkyl group. It is therefore reported that methyl is mainly suitable for metals, ethyl for rubber, plastics, wood, isobutyl for medical use, and oligomeric forms for porous use.

However, cyanoacrylates prepared by this method generally have low purity, poor adhesion performance, stability, and the like, and thus have been distilled back into purified cyanoacrylates.

Regarding distillation and purification of cyanoacrylate, in order to prevent polymerization of 2-cyanoacrylate, anionic polymerization inhibitors such as diphosphorous pentoxide (P ₂ O ₅ ), phosphoric acid, paratoluenesulfonic acid, hydroquinone, catechol, There is known a method of adding a radical polymerization inhibitor such as pyrogallol to the prepared 2-cyanoacrylate, and distilling under reduced pressure.

At this time, it is important to remove the water produced in the manufacturing process as described above, but if there is a lot of moisture hydrolyzes the cured product, the adhesive strength drops sharply, and formaldehyde is released by hydrolysis, which is harmful. there was.

Therefore, volatile organic compounds (VOCs) such as toluene, xylene, isopropyl alcohol, methyl ethyl ketone (MEK), paraffin, acetone, etc. are commonly used for the removal of water. However, these solvents are harmful to the human body as a carcinogenic harmful substance, there was a problem that the main culprit of air pollution.

On the other hand, methylenemalonate is another type of monomer used as a main component of the instant adhesive. The methylenemalonate is also prepared by a method similar to the preparation of cyanoacrylate. For example, US Patent No. 3197318 proposes a method for preparing dimethyl 2-methylenmalonate, and US Patent No. 3523097 discloses diethyl 2-methylenmalonate. A manufacturing method has been proposed, and a method of preparing diethyl ethoxy-methylenmalonate has been proposed in US Patent 3221745.

However, the main components of the instant adhesive prepared by the method described in the US patent also used a solvent harmful to the human body for the generation and removal of water, and the problem that the amount of formaldehyde remaining is harmful to the human body when used in excess. there was.

The present invention is to solve the above problems,

It is a method of preparing dimethyl 2-methylenemalonate which is used as a main component of instant adhesive because it is harmless to human body by preventing the use and occurrence of carcinogenic harmful substances, has excellent solubility and thermal stability, and has good adhesiveness and easy removal of water. It aims to provide.

The present invention to achieve the above object,

In the manufacturing method of dimethyl 2-methylenemalonate which synthesize | combines a polymer by the condensation reaction of formaldehyde and malonate, and heat-depolymerizes under vacuum,

It provides a method for producing dimethyl 2-methylenemalonate, characterized in that a solvent having a lower density than the water and a boiling point of 74 ~ 177 ℃ when synthesizing the polymer.

In addition, the solvent is characterized in that any one selected from methyl isobutyl ketone, acetic acid, ethyl acetate.

In addition, the synthesis of the polymer is mixed with a solvent, formaldehyde under a basic catalyst and maintained at 70 ~ 80 ℃ and stirred for 150 minutes, then dropwise or added all the malonate and reacted for 240 minutes while maintaining 100 ~ 110 ℃, Distillation to remove the solvent and water, and vacuum filtration to obtain a dimethyl 2-methylenemalonate liquid polymer, vacuum distillation to obtain a dimethyl 2- methylenemalonate polymer.

The solvent may be used in an amount of 200 to 300 parts by weight based on 100 parts by weight of formaldehyde and malonate.

In addition, the amount of formaldehyde is characterized in that 0.25 ~ 0.6mole compared to malonate 0.5mole.

As described above, the dimethyl 2-methylenemalonate prepared by the method for preparing dimethyl 2-methylenemalonate according to the present invention can be controlled to use a safe solvent other than VOCs and to reduce the amount of harmful substances such as formaldehyde. It is harmless to the human body, it is excellent in the water removal effect through the solvent, storage stability and thermal stability is given, and has the effect that it can be used as an adhesive having excellent adhesion.

1 is a process chart showing a method for preparing dimethyl 2-methylenemalonate according to an embodiment of the present invention.
2 is a process chart showing a method for preparing dimethyl 2-methylenemalonate according to another embodiment of the present invention.
Figure 3 is the FT-IR analysis of the dimethyl 2-methylenemalonate prepared in Example 1.

Hereinafter, a method for preparing dimethyl 2-methylenemalonate according to the present invention will be described in more detail with reference to the drawings, which are presented to assist in understanding the present invention, but the present invention is not limited thereto.

1 is a process chart showing a manufacturing method of dimethyl 2-methylenemalonate according to an embodiment of the present invention, Figure 2 is a process chart showing a manufacturing method of dimethyl 2-methylenemalonate according to another embodiment of the present invention.

The present invention relates to a method for preparing pure dimethyl 2-methylenemalonate which can be used as a main raw material of an instant adhesive. The dimethyl 2-methylenemalonate prepared by the method of the present invention is a release amount of toxic substances. It has less properties, has excellent adhesiveness, solubility and thermal stability when manufactured with an adhesive, and can be produced with an adhesive having a predetermined hardness and flexibility.

The dimethyl 2-methylenemalonate is a method of producing dimethyl 2-methylenemalonate which is synthesized by condensation reaction of formaldehyde and malonate, and then depolymerized by heating under vacuum. It is possible by using the solvent which is 74-177 degreeC.

The solvent effectively removes water generated during the synthesis of the polymer to prevent side reactions, and the reaction of the malonate and formaldehyde without reaction is performed smoothly to reduce the content of formaldehyde contained in the prepared dimethyl 2-methylenemalonate. It plays an important role in minimizing the generation of harmful substances due to side reactions.

In this case, by controlling the ratio of malonate and formaldehyde together with the solvent, and by controlling the temperature during distillation, water can be more effectively removed to minimize the generation of harmful substances due to side reactions.

In addition, since the density can be easily determined whether the separation is lower than water, if the density is higher than water, it may not be easy to remove the water when quantitating moisture. Therefore, it is preferable to use a solvent having a density lower than the density 1 of water, and more specifically, one having a density of 0.75-0.95 can be more preferably used.

In addition, if the boiling point is less than 74 ℃ temperature is too low unsuitable for water removal, on the contrary, if the boiling point of the malonate exceeds 177 ℃ there is a problem that dimethyl 2-methylenemalonate is distilled before the synthesis is completed is unsuitable. .

In the present invention, it is preferable to use any one selected from methyl isobutyl ketone, acetic acid and ethyl acetate as a solvent harmless to the human body while satisfying the above conditions, and in particular, it is preferable to use methyl isobutyl ketone. It is more preferable because it shows excellent physical properties.

In more detail, the dimethyl 2-methylenemalonate manufacturing method according to the present invention will be described sequentially. First, in order to synthesize the polymer, a solvent and formaldehyde are mixed under a basic catalyst, and then stirred at 150 ° C. for 70 minutes to 80 ° C. , Malonate is added dropwise as shown in FIG. 1 or all added as shown in FIG. 2. At this time, an exothermic reaction occurs and the reaction is carried out for 240 minutes while maintaining 100 to 110 ° C. Thereafter, the solvent and water are distilled off to remove the solvent, followed by vacuum filtration to obtain a dimethyl 2-methylenemalonate liquid polymer, which is then vacuum distilled to obtain a dimethyl 2-methylenemalonate polymer.

Synthesis of the dimethyl 2-methyllinmalonate polymer through the formaldehyde and malonate can be produced through a complex reaction as shown in Scheme 1, by depolymerizing the polymer thus synthesized in a vacuum at 150 ~ 260 ℃ Dimethyl 2-methylenemalonate (Formula V of Scheme 1) used as the main component of the adhesive can be prepared.

[Reaction Scheme 1]

In this case, piperidine, diethylamine, dibutylamine, morpholine, potassium hydroxide, sodium hydroxide, sodium alkoxide, etc. may be selectively used as the basic catalyst, and the basic catalyst is based on 100 parts by weight of malonate. It is preferable that 15-25 weight part is used.

If the amount of the basic catalyst is out of the above range, the generation or removal of water generated during the reaction of malonate and formaldehyde may not be easily performed, and thus the production rate of dimethyl 2-methylenemalonate may be reduced.

The solvent is preferably used in an amount of 200 to 300 parts by weight based on 100 parts by weight of formaldehyde and malonate. If the amount of the solvent is used in an amount less than 200 parts by weight, the dissolution of malonate and formaldehyde is sufficient. Other side reactions may occur. In addition, when the amount of the solvent used exceeds 300 parts by weight, the remaining amount may be largely removed when the solvent is removed later.

On the other hand, the amount of formaldehyde is preferably 0.25 ~ 0.6mole compared to 0.5 mole of malonate, if the amount of formaldehyde is used less than 0.25 mole compared to 0.5 mole (mole) of malonate, the reaction is not sufficiently made dimethyl- When the yield of 2-methylenemalonate is lowered and used more than 0.6 moles, the reaction is sufficiently performed, but the amount of formaldehyde remaining is increased, and the removal of water is not effective, and harmful substances may be generated due to side reactions. At this time, the use of the formaldehyde and malonate in a molar ratio of 1: 1 is more preferable because it can be completely reacted without remaining components.

The present invention will be described in more detail with reference to the following examples. However, the following examples are only presented to aid the understanding of the present invention, and the claims of the present invention are not limited thereto.

≪ Example 1 >

10 g of piperidine, 15 g of paraformadehyde, and 250 g of methyl isobutyl ketone (d = 0.800) as a solvent were mixed and the mixture was stirred at 70 to 80 ° C. for 150 minutes, followed by dimethyl 66 g of malonate was added dropwise for 20 minutes, and the reaction mixture was maintained at 100 to 110 ° C. for 240 minutes while the water determination device and the reflux cooler were installed, followed by distillation to remove the solvent and water, followed by vacuum filtration. Methylenemalonate liquid polymer was obtained, and vacuum distillation was carried out to distill the methyl isobutyl ketone remaining in the liquid polymer in the first step, and to obtain the dimethyl 2-methylenemalonate polymer in the second step. Depolymerization was carried out to prepare dimethyl 2-methylenemalonate used as the main component of the adhesive.

<Example 2>

Dimethyl 2-methylenemalonate was prepared in the same manner as in Example 1 except that ethyl acetate (Ethyl acetate (d = 0.897)) was used as a solvent.

&Lt; Comparative Example 1 &

Dimethyl 2-methylenemalonate was prepared in the same manner as Example 1 except for using toluene (Toluene (d = 0.867)) as a solvent.

Comparative Example 2

Dimethyl 2-methylenemalonate was prepared in the same manner as in Example 1, except that trichloroethylene (Trichlorethylene (d = 1.460)) was used as a solvent.

<Experimental Example 1>

As a result of confirming the production state of the dimethyl 2-methylenemalonate prepared in Example 1, Example 2 and Comparative Examples 1 to 2, in the case of Example 1 and Comparative Example 1 was effectively removed water pure dimethyl 2-methylene Malonate could be obtained. In Example 2, although the density of the solvent was sufficiently low compared to water, the boiling point was too low, and the water removal effect was slightly inferior to that of Example 1. In the case of Comparative Example 2, since the density is higher than that of water, water is not easily removed during water quantification, and thus it is difficult to obtain pure dimethyl 2-methylenemalonate.

In addition, FT-IR analysis was performed to confirm whether synthesis of dimethyl 2-methylenemalonate prepared in Example 1 was properly performed, and the results are shown in FIG. 3.

As shown in FIG. 3, the dimethyl 2-methylenemalonate prepared in Example 1 was confirmed to be well synthesized through a C = CH ₂ double bond.

<Example 3>

Dimethyl 2-methylenemalonate was prepared in the same manner as in Example 1 except that all of the dimethylmalonate was added.

<Experimental Example 2>

The amount of water generated during the preparation of the dimethyl 2-methylenemalonate prepared in Examples 1, 3 and Comparative Example 1 was checked through a water determination device and a reflux cooler, and the residual amount of formaldehyde and the amount of VOCs were measured. The results are shown in Table 2 below. At this time, the test method and the standard used for the residual amount of formaldehyde and VOCs detection were used in the method of Table 1 below.

Test Items Test Methods Remarks Reference value Standard Products Formaldehyde US EPA 8315 A: 1996 HPLC 20 mg / kg or less Safety Certification Safety Standard Annex 01 (Acceleration Eyelashes) Accelerated eyebrow glue VOCs (Benzene, Toluene, Xylene) US EPA 5021: 1996 Headspace-GC / MS 20 mg / kg or less KS M 0031: 2002 GC / FID

Test result (mg / kg) ACN extraction DW extraction Benzene Toluene Xylene Example 1 26 8 ND 4 ND Example 3 ND ND ND ND ND Comparative Example 1 174 249 ND 7.2 1320

ND: not detected

As shown in Table 2, in the case of Example 1 and Example 3, it was confirmed that the residual amount of formaldehyde or VOCs was not detected or very low regardless of the method of adding the solvent, and thus the level did not affect the human body.

On the other hand, in the case of Comparative Example 1 using toluene as a solvent, the residual amount of formaldehyde in the prepared dimethyl 2-methylenemalonate was found to be harmful to the human body.

<Examples 4 to 6>

Dimethyl was prepared in the same manner as in Example 3, except that the amount of paraformaldehyde was prepared while changing from 0.5 mole of malonate to 0.25 (Example 4), 0.3 (Example 5), 0.45 (Example 6) mole. 2-methylenemalonate was prepared.

<Experimental Example 3>

The amount of water produced during the preparation of dimethyl 2-methylenemalonate prepared in Examples 3 to 6 was confirmed, and the residual amount of formaldehyde and the amount of VOCs detected were measured, and the results are shown in Table 3 below. At this time, the test method and standard used for the residual amount of formaldehyde and VOCs detection are the same as the method of Table 1.

Test result (mg / kg) ACN extraction DW extraction Benzene Toluene Xylene Example 3 ND ND ND ND ND Example 4 ND ND ND ND ND Example 5 ND ND ND 39 ND Example 6 11 ND ND 6 ND

ND: not detected

As shown in Table 3, all of the dimethyl 2-methylenemalonate prepared by the use amount of formaldehyde and malonate presented in the present invention was confirmed that little or no harmful substances were detected.

That is, the dimethyl 2-methylenemalonate prepared by the production method according to the present invention can be used as the main component of the instant adhesive which is harmless to the human body since no residual amount of formaldehyde or volatile organic compounds (VOCs) is detected or hardly remained in the component. And it was found.

Claims (5)

In the manufacturing method of dimethyl 2-methylenemalonate which synthesize | combines a polymer by the condensation reaction of formaldehyde and malonate, and heat-depolymerizes under vacuum,
A method for producing dimethyl 2-methylenemalonate, characterized in that a solvent having a lower boiling point than water and having a boiling point of 74 to 177 ° C when synthesizing a polymer. The method according to claim 1,
The solvent is a method for producing dimethyl 2-methylenemalonate, characterized in that any one selected from methyl isobutyl ketone, acetic acid, ethyl acetate. The method according to claim 2,
In the polymer synthesis, a solvent and formaldehyde were mixed under a basic catalyst and maintained at 70 ° C. to 80 ° C., followed by stirring for 150 minutes. Then, malonate was added dropwise or added thereto. A solvent and water are removed, and vacuum filtration to obtain a dimethyl 2-methylenemalonate liquid polymer, which is vacuum distilled to obtain a dimethyl 2-methylenemalonate polymer. The method according to claim 3,
The solvent is a method for producing dimethyl 2-methylenemalonate, characterized in that 200 to 300 parts by weight based on 100 parts by weight of formaldehyde and malonate used. The method according to claim 3,
Formaldehyde is used in the production method of dimethyl 2-methylenemalonate, characterized in that 0.25 ~ 0.6mole compared to malonate 0.5mole.

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