TW201739805A - Method for producing 2-cyanoacrylate - Google Patents

Abstract

To provide a method for depolymerizing a polycondensate of 2-cyanoacrylate at a low temperature in a short time and obtaining high-purity 2-cyanoacrylate. A method for producing 2-cyanoacrylate, said method being characterized in that a basic substance is added to a solution of a polycondensate of a cyanoacetic acid ester and formaldehyde, depolymerization is performed, an acid is added to the resulting depolymerized composition for neutralization, and the generated salt is removed.

Description

Method for producing 2-cyanoacrylate (salt)

The present invention relates to a method for producing 2-cyanoacylate which is widely used as an instant adhesive.

2-cyanoacrylate (salt) quickly initiates polymerization by a little moisture existing near the surface of the adherend, and the adherends made of various materials are in a very short time of several seconds to several minutes. All of them are bonded, and because of their strong adhesion, they are used as a main component of instant adhesives in a wide range of fields such as electrical appliances, electronics, mechanical parts, precision machinery, household goods, and medical care.

A method for producing 2-cyanoacrylate (salt), which is widely used today, is a method using cyanoacetic ester and paraformaldehyde as raw materials. USP2721858: Japanese Patent No. 35-10309 Is an industrially efficient method. The manufacturing method is constituted by the following three manufacturing processes, that is, in the first manufacturing process, cyanoacetic ester and paraformaldehyde are in piperididine, etc. Condensation occurs in an organic solvent in the presence of a basic catalyst; in the second manufacturing procedure, the 2-cyanoacrylate polycondensate obtained in the first manufacturing procedure In the presence of a polymerization inhibitor such as diphosphorus pentaoxide, depolymerization is carried out under conditions of high temperature decompression; in the third manufacturing procedure, 2-derived by depolymerization The cyanoacylate monomer is distilled to obtain a purified 2-cyanoacrylate monomer.

However, in the method for producing 2-cyanoacrylate (salt), the high boiling point of 2,4-dicyanoglutaric diester or the like in the late stage of depolymerization of the second production procedure A large amount of by-products are distilled off; in addition, in order to increase the rate of formation of unrefined 2-cyanoacrylate (salt) monomer, long-term depolymerization is carried out, and instead, abnormal decomposition reaction is easily caused. , the number of impurities increased. As a result, in order to increase the production rate of the unpurified 2-cyanoacrylate (salt) monomer, the purity of the unpurified 2-cyanoacrylate monomer was lower.

On the other hand, a polymer of buty cyanoacylate dissolved in a solution of tetrahydrofuran (THF; tetrahydrofuran), hereinafter referred to as "THF", exists in Tetrabutylammonium hydroxide. The depolymerization is rapidly carried out at room temperature, and the polymer is repolymerized soon after the formation of the monomer to form a polymer having a lower molecular weight than the original molecular weight, which has been disclosed in the non-patent literature. [Prior technical literature] [Non-patent literature]

Polymer Journal, Macromolecular Rapid Communications, 17 (pp. 217-227 (1996)).

[The problem to be solved by the present invention]

However, the technique described in the above non-patent literature, the polymer of butyl cyanoacrylate becomes a reconstitution machine of a polymer having a lower molecular weight, and there is no disclosure about the production of a monomer.

The problem to be solved by the present invention is to provide a method for producing a 2-cyanoacrylate (salt) monomer, which is capable of providing depolymerization at a low temperature for a short period of time and maintaining a high degree of 2-cyanoacrylate ( Salt) A method of purity and production rate of a monomer. 【way of solving the problem】

The present inventors focused on the depolymerization reaction in the production of a 2-cyanoacrylate (polycarbonate) polycondensate, and found that if a basic substance is added to the 2-cyanoacrylate (condensate) polycondensate, Then, the depolymerization reaction can be carried out at room temperature for several minutes; further, it is found that after the depolymerization, the acid is added to neutralize the basic substance, and the amount of the 2-cyanoacrylate (salt) monomer is increased by a breakthrough; Further, it has been found that the salt produced in the neutralization process is removed by filtration, and the monomer can be stably obtained, and the present invention has been completed. That is, the present invention includes a 2-cyanoacrylate characterized by adding a basic substance to a solution of a polycondensate of cyanoacetate and formaldehyde to depolymerize the polycondensate. a method for producing a salt; and a method comprising: adding an acid to the depolymerization reaction solution obtained by the depolymerization operation step to neutralize the operation, and removing the salt formed in the neutralization operation program; A method for producing 2-cyanoacrylate (salt). [Results of the invention]

The present invention relates to the production of 2-cyanoacrylate (salt), since the depolymerization reaction can be carried out at a low temperature and in a short time, and a high-purity 2-cyanoacrylate (salt) monomer having few impurity components can be produced. In addition, productivity can be improved.

Hereinafter, the present invention will be described in detail. The chemical formula of 2-cyanoacrylate (salt) suitable for use in the present invention is shown below.

CH ₂ =C(CN)COOR (1) In the above chemical formula (1), R system: a saturated or unsaturated linear hydrocarbon group of 1 to 20 carbon atoms which may also contain a halogen atom (hydrocarbon group) a branched chain hydrocarbon group or an alicyclic hydrocarbon group; an aromatic hydrocarbon having 1 to 20 carbon atoms; a cyclic ether; or a chemical formula - (CH) ₂ ) _m (OA) _n H "In the chemical formula, each of the carbon atoms 1 to 10 independently of the A system is preferably an alkylene group of 2 to 6 or a divalent alicyclic hydrocarbon group or an aromatic hydrocarbon group. m and n are 1 or more, m+n is 2 to 20, m is preferably 2 to 4, and n is preferably an ether linkage chemical group represented by 1 to 3, and ether linkage. Any one or all of the aforementioned alkylene group and hydrocarbon group may have a halogen atom.

Specific examples of the 2-cyanoacrylate (salt) represented by the above chemical formula (1) include methyl ester, ethyl ester, chloroethyl, and chloroethyl 2-cyanoacrylate. -propyl-propyl, i-propyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, positive Amyl ester, 1-methyl-butyl ester, 1-ethyl-butyl ester, neopentyl, n-hexyl ester, 1-methylpentyl ester, n-heptyl, n-octyl Ester, n-decyl ester, n-decyl, n-undecyl, n-dodecyl, cyclohexyl ester, benzyl, benzene Ester (phenyl), tetrahydrofurfuryl, allyl, propargyl, 2-butenyl, phenethyl, chloropropyl, Ethoxyethyl, ethoxypropyl, ethoxy isopropyl, propoxyethyl, isopropoxyethyl, butoxyethyl, methoxypropyl ( Methoxypropyl), methoxyisopropyl ester, methoxy Butyl ester, propoxymrthyl, propoxypropyl propyl, butoxymethyl, butoxyethyl, butoxypropyl, butoxypropyl, butoxybutyl, Isoonyl, iso-decyl, cyclohexylmethyl, naphthyl, 2-(2'-methoxy)-ethoxyethyl ester (2-(2) '-methoxy)-ethoxyethyl), 2-(2'-ethoxy)-ethoxyethyl ester, 2-(2'-propoxy)-ethoxyethyl ester, 2-(2'-butoxy Ethyl ethoxyethyl ester, 2-(2'-pentyloxy)-ethoxyethyl ester, 2-(2'-hexyloxy)-ethoxyethyl ester, 2-(2'-A 2-(2'-methoxy)-propoxypropyl, 2-(2'-ethoxy)-propoxypropyl, 2-(2'-propoxy)- Propyloxypropyl, 2-(2'-pentyloxy)-propoxypropyl, 2-(2'-hexyloxy)-propoxypropyl Ester, 2-(2'-methoxy)-butoxybutyl, 2-(2'-ethoxy)-butoxybutyl ester, 2- (2'-butoxy)-butoxybutyl ester, 2-(3'-methoxy)-propoxyethyl ester, 2-(3'-methoxy)-butoxyethyl ester, 2 -(3'- Oxy)-propoxypropyl ester, 2-(3'-methoxy)-butoxypropyl ester, 2-(2'-methoxy)-ethoxypropyl ester, 2-(2'- An ester such as methoxy)-ethoxybutyl ester, which can be used as a main component or a subcomponent of a cyanoacrylate type instant adhesive.

The unit of the polycondensate cyanoacrylate in the present invention is based on the cyanoacrylate produced by the depolymerization reaction and the 2,4-dicyanoglutaric diester (2,4-dicyanoglutaric diester). 1) Obtained for the basic calculation.

[Number 1] (1)

The basic substance in the present invention is not particularly limited as long as it exhibits a well-known basicity, and can be used. When the basic dissociation constant (pKb) of the basic substance becomes high, the rate of the depolymerization reaction becomes slow. Therefore, the basic substance having an alkali dissociation constant of 6 or less is more desirable, and more desirable is The basic substance having an alkaline dissociation constant of 3 or less is more preferably an alkaline substance having a basic dissociation constant of 0 to 3. When pKb is less than 0, the stability of the monomer generated by the depolymerization may be lowered, and the production rate may be lowered. The basic dissociation constant pKb in the present invention is calculated according to the following mathematical formula (2). pKb=14-pKa (2)

The pKa is an acid dissociation constant, and a generally known document such as the values described in "Maruzen Chemicals Handbook", Chapter II, Chapter 10, etc.; and, for example, alkaline dissociation not described in the literature are known. The constant pKb value can be determined, for example, by an acid-base neutralization reaction; the alkaline substance can also be titrated with an aqueous solution of an appropriate acid standard such as hydrochloric acid or oxalic acid, and the The titration curve can be obtained. The acid dissociation constant and the basic dissociation constant are usually values measured in an aqueous solution at a normal pressure of "1 atm." at 25 ° C. The basic dissociation constant in the present invention is also a value measured in the same manner.

As the alkaline substance, it is preferred from an amine, a phosphine, a thiolate, an alkoxide, a quaternary ammonium salt, and an alkali metal and/or an alkaline earth metal. One or more of oxides, hydroxides, carbonates, phosphates, and silicates are used. From the viewpoint of solubility in a solvent or salt precipitation property at the time of neutralization, an amine is preferable, and a specific example of the amine may be exemplified by methylamine or dimethylamine. , trimethylamine, ethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, diethylene tetramine, aniline Aniline), N,N-diisopropylethylamine, tetramethylethylenediamine, 4-aminopyridine, N,N-dimethyl- 4-aminopyridine, imidazole, 1,4-diazabicyclo[2.2.2]octane (1,4-Diazabicyclo[2.2.2]octane), cyclohexylamine, 2,6-dimethyl Pyridine, 1,4,7,10-tetraazacyclododecane, 2,4,6-tris(dimethylaminomethyl)phenol (2,4 ,6-Tris(dimethylaminomethyl)phenol) "hereinafter referred to as "DMP-30", three (hydroxymethyl) methylamine, 2,4,6-trimethyl Pyridine, piperazine, piperididine, pyridine, pyrrolidine, 1,2-propanediamine, 1,3-propanediamine, 1, 6-hexanediamine, hexylamine, benzylamine, 1-methylimidazole, 2-methylimidazole, 2-methylpyridine, 4-methylpyridine, 3-methyl Pyridyl and the like, wherein a large amount of monomeric product of piperidine is preferred; specific examples of phosphine include methylphosphine, ethylphosphine, dimethylphosphine, and Ethylphosphine, trimethylphosphine, triethylphosphine, phenylphosphine, diphenylphosphine, triphenylphosphine, etc.; specific examples of the thiolate, which may be exemplified by: methyl mercaptan (methanethiol), ethanethiol, 1-propanylthiol, 2-propanethiol, 1,2-ethanedithiol, 1,3-propane A conjugate base of a thiol, a thiophenol or the like; a specific example of an alkoxide, which is methoxide (m) Ethoxide), ethoxide, 1-propoxide, 2-propoxide, 1-butoxide, 2-methyl-1-propanolate, 2- Butanol salt, 2-methyl-2-propanol salt and the like; specific examples of the quaternary ammonium salt may be exemplified by: chlorodimethylammonium chloride "hydroxychloroaniline; chlorinated alkane Benzalkonium chloride, benzethonium chloride, methylbenzethonium chloride, chlorinated ten Hexylpyridinium chloride, cetylpyridinium chloride, cetyltrimethylammonium chloride, cetyltrimethylammonium chloride "cetrimonium bromide; cetyltrimethylammonium bromide", tetramethylammonium hydroxide "tetramethylammonium hydroxide", tetraethylammonium hydroxide "tetraethylammonium hydroxide", tetrapropyl hydroxide Ammonium, tetrabutylammonium hydroxide, dopoammonium chloride (dofan Olium chloride), tetraethylammonium bromide, didecyldimethylammonium chloride, degree of bromination Domiphen bromide and the like; specific examples of oxides, hydroxides, carbonates, phosphates, and silicates of alkali metals and/or alkaline earth metals, which may be exemplified by sodium oxide (Sodium oxide) ), potassium oxide, calcium oxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, magnesium carbonate, calcium carbonate, sodium phosphate, potassium phosphate, calcium phosphate, magnesium phosphate, sodium citrate, citric acid Potassium and so on.

The amount of the basic substance to be added is preferably 0.001 to 5 times the molar equivalent of the basic substance based on the cyanoacrylate unit of the 2-cyanoacrylate (salt) polycondensate, more preferably 0.1 to 0.1. The amount of 3 times the molar equivalent is more preferably an amount of 1 to 2 times the molar equivalent. If it is less than 0.001 times the molar equivalent, it is difficult to carry out the depolymerization; when it is 0.001 times the molar equivalent or more, although the depolymerization reaction proceeds, when it exceeds 5 times the molar equivalent, 2-cyanide is produced. The salt of 5 times molar equivalent or more of the acrylate monomer may promote the polymerization of the 2-cyanoacrylate monomer, and the monomer formation rate may be lowered.

In the present invention, as the solvent to be used, an organic solvent having an ether, ketone and/or ester structure, that is, ether, ketone and/or is preferable. Or an ester is more desirable; in particular, since a depolymerization reaction is fast, tetrahydrofuran (hereinafter, referred to as "THF" or acetone (acetine) is preferably an organic solvent having a high polarity. Further, toluene, xylene, benzene, trichloroethylene, cyclohexane, and ethyl acetate used in the condensation procedure of 2-cyanoacrylate (salt) Ethyl acetate, methanol, ethanol, isopropanol, tricresyl phosphate, dioctyl phthalate, dioctyl phthalate, diphenyl phenyl phosphate Diphenylphenyl phosphate or the like may be used as a part or all of the above organic solvent.

The weight average molecular weight "Mw" of the polycondensate of 2-cyanoacrylate (salt) is preferably from 1,000 to 10,000, more preferably from 1,500 to 5,000. When the weight average molecular weight exceeds 10,000, the viscosity of the polycondensate becomes high, and the efficiency of depolymerization is deteriorated; when the weight average molecular weight is less than 1,000, 2,4-dicyanopentane remains after depolymerization. There are many diacid diesters and the like, and there is a case where the monomer formation rate is lowered.

Further, the number average molecular weight "Mn" and the weight average molecular weight "Mw" in the present invention are determined by gel permeation chromatography (hereinafter referred to as "GPC"). The value. On the gel permeation chromatograph, tetrahydrofuran was used as a mobile phase, and a polystyrene gel column was used, and the temperature was set at 40 °C. The value of the molecular weight was determined in terms of polystyrene.

The temperature of the depolymerization procedure is preferably from 0 to 130 ° C; if it is less than 0 ° C, the depolymerization rate is low, and the depolymerization efficiency is deteriorated; and if it exceeds 130 ° C, the decomposition reaction is abnormal. The amount of impurities increases, and there is a case where the monomer generation rate is lowered.

The substance which is an acid is not particularly limited as long as it can react with a basic substance, and examples thereof include those which are acidic when dissolved in water or alcohol, and which are not dissolved in water or alcohol but are not dissolved in water or alcohol. A salt obtained by a Brønsted base or a Lewis base reaction. Specific examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, polyphosphoric acid, methane sulfonic acid, benzene sulfonic acid, and p-toluenesulfonic acid (p). -toluenesulfonic acid) hereinafter referred to as "PTS", sulfonic acid such as 10-Camphorsulfonic acid; acid chloride, acetic acid, carbonic acid, and the like. More desirable are inorganic acids, sulfonic acids, mercapto chlorides, etc., among which monovalent acids and water-free ones are preferred; from the viewpoint of salt precipitation or handling, sulphur Acids are particularly desirable, and methanesulfonic acid is more desirable.

The neutralization procedure is not particularly limited, and may be continuous or batch; since the temperature of the system is raised due to the heat of neutralization, it is preferable to perform cooling while performing.

The method for removing the salt to be formed is not particularly limited, such as filtration, centrifugal separation, decantation, and the like, and may be continuous or batch.

In order to remove the organic solvent or a trace amount of water remaining in the depolymerized composition obtained after the filtration, a polymer which is an impurity, or the like, the distillation is further carried out, whereby the purity of the monomer can be further increased. After distilling off the organic solvent, it is preferred to heat the under reduced pressure of 0.01 to 1.33 kPa (kilopascal) to distill the 2-cyanoacylate in the depolymerized composition; At the time of distillation, diphosphorus pentaoxide, sulfur dioxide (SO ₂ ), phenyltrichlorosilane (PTS; phenyltrichlorosilane), boron trifluoride (BF ₃ ; Boron) are added to the depolymerized composition of the pot. Anionic polymerization inhibitors such as Trifluoride, Propane sultone, methane sulfonic acid, etc. are ideal; in addition, hydroquinone or hydroquinone is added to hydroquinone Radical polymerization inhibitors such as hydroquinone monomethyl ether and pyrogallol are also desirable. [Examples]

Hereinafter, the present invention will be specifically described in more detail by way of examples, but the invention is not limited thereto.

[1] Depolymerization method of 2-cyanoacrylate (salt) polycondensate * Example 1 Polycondensate of ethyl-2-cyanoacylate "120 g, weight average molecular weight = 2,183 , the number average molecular weight = 1,238, ethyl cyanoacrylate monomer equivalent to 0.78 moles dissolved in 280 ml of tetrahydrofuran, piperidine (66.4 grams, 0.78 moles) was added, after stirring at room temperature for 10 minutes, Phenyltrichlorosilane (PTS; phenyltrichlorosilane) "141.2 g, 0.82 mol" was added, neutralized, and the salt was precipitated; the precipitated salt was filtered off with a glass filter, and the phenyl group was distilled off under reduced pressure. Trichloromethane, which gave a depolymerized composition of 115.2 g "96%".

* Example 2 The acid to be added to the solution to be polymerized was methane sulfonic acid, and the same depolymerization reaction as in Example 1 was carried out.

* The amount of piperidine added to the solution of Examples 3 to 5 was 0.1, 1, 2, and 5, respectively, based on the monomer calculated from the number average molecular weight of the polycondensate. The same depolymerization reaction as in Example 1 was carried out except for the Momo equivalent.

* Examples 6 to 9 Basic substances were used in the same manner as in Example 2 except that the basic substance contained in Table 1 was used.

* Examples 10 to 12 The organic solvent in which the polycondensate was dissolved was ethyl acetate, acetone, and toluene, and the same depolymerization reaction as in Example 2 was carried out.

* Examples 13 to 15 The type of polycondensate used was methyl cyanoacrylate "weight average molecular weight = 1,600", isopropyl cyanoacrylate "weight average molecular weight = 2,200", ethoxyethyl cyanoacrylate "weight average Molecular weight = 2,200", except that the same depolymerization reaction as in Example 2 was carried out.

* The amount of piperidine added to the solution of the polycondensate of Examples 16 and 17 was 0.001 times and 0.01 times of the molar equivalent of the cyanoacrylate unit calculated by the formula (1). Except for the same, the same depolymerization reaction as in Example 2 was carried out.

* Examples 18 to 20 The same depolymerization reactions as in Examples 2 to 4 were carried out, except that no acid was added.

* Example 21 The precipitated salt was removed without using a glass filter, and the same depolymerization reaction as in Example 2 was carried out.

* Comparative Example 1 No piperidine was added, and the same depolymerization reaction as in Example 2 was carried out.

* Comparative Example 2 Hydroquinone "1.01% by weight" and diphosphorus pentaoxide "0.76% by weight" were added to the polycondensate of ethyl cyanoacrylate as individual bath stabilizers. (tank liquid stabilizer), under normal pressure, the reaction vessel temperature was 25 ° C, and the depolymerization reaction was carried out for 10 minutes.

* Comparative Example 3 The reaction tank temperature was 200 ° C, and the same depolymerization reaction as in Comparative Example 2 was carried out.

* Comparative Example 4 The polymerization reaction time was 360 minutes, and the same depolymerization reaction as in Comparative Example 3 was carried out.

[2] Method for Calculating Weight Average Molecular Weight (Mw) The weight average molecular weight in Table 1 is obtained by diluting the depolymerized composition produced in [1] with tetrahydrofuran by gel permeation chromatography (GPC). Based on the measurement, it is calculated. As a gel permeation chromatograph, HLC-8220 manufactured by TOSOH Co., Ltd. was used, and tetrahydrofuran was used as a mobile phase, and a polystyrene gel column (TSKgel G2500 HxL manufactured by TOSOH Co., Ltd.) was used. 6.0 mm X length 30 cm>, 2 pieces; temperature set at 40 ° C, flow rate: 1.0 ml / min, using radioactive isotope detection and measurement. The value of the weight average molecular weight is determined by a value in terms of polystyrene. In addition, when a polycondensate having a weight average molecular weight of 1,000 or more is not contained, it is represented by "N.D.".

[3] Calculation method of monomer concentration in the depolymerized composition The monomer concentration in Table 1 is determined by "nuclear magnetic resonance spectrometry" (hereinafter, " ¹ H-NMR" Based on the measurement, the integral ratio of the protons of the proton and the ester function bound to the C=C double bond is determined. Based on the following mathematical formula (3), each is calculated. The proportion of cyanoacrylate (salt) monomer. The ester group in the formula (3) is a condensation polymer and a decomposition product thereof, and an ethyl ester group, a methyl ester group, an isopropyl ester group or an ethoxyethyl group contained in the monomer. The sum of the ester groups.

Monomer concentration = (monomer [mole]) / (ester group [mole]) X 100 (%) (3)

[4] Stability of the depolymerized composition After the reaction mixture is allowed to stand at room temperature for 12 hours or more, the concentration of the monomer in the depolymerized composition is 80% or more of the initial value, and is represented by ○; 80% of them are represented by Δ; those of less than 10% are represented by r; thereby determining the stability of the depolymerized composition.

【Table 1】

The results of the respective examples and comparative examples are shown in Table 1. According to the results, when a piperylene having a polycondensate cyanoacrylate unit of 1 time molar equivalent is added to the tetrahydrofuran solution of the polycondensate, at 25 ° C, The solution is quickly depolymerized in 10 minutes. Next, since the acid is added and the salt formed is removed, 50% or more of the monomer is produced in Examples "1 and 2"; when the piperidine is 0.1 times, 2 times, or 5 times the molar equivalent, and 1 time In the case of the molar equivalent, although the concentration of the monomer is low, 10% or more of the monomers "Examples 3 to 5" are produced; on the other hand, if added to the monomer calculated from the polycondensate, In the case of an alkaline substance which does not have 1 molar equivalent, the weight average molecular weight hardly changes, and only 1% of the monomer is produced (Examples 16 and 17). Further, when piperidine was not added and only an acid was added, "Comparative Example 1" was not produced at all in the monomer. When piperidine is added to depolymerize, and then no acid is added, although the monomer is formed, the concentration of the monomer is lower than that in the case of adding an acid; in addition, the depolymerized composition is unstable, Polymerization was repeated within a few hours to further reduce the monomer concentration (Examples 18-20). When piperidine is added to depolymerize and then acid is added, if the precipitated salt is not removed, the salt reacts with the formed monomer, and when tetrahydrofuran is distilled off, the polymerization proceeds again, and the monomer disappears. Example 21".

Further, in the case where the type of the added basic substance is changed, although any one undergoes a depolymerization reaction, in particular, a base having a low basic dissociation constant (pKb), the depolymerization reaction proceeds rapidly, and the monomer concentration Increasingly, "Examples 6 to 9". In the case where the solvent used in the reaction is changed, the monomer concentration in the case of using acetone is 54%, which is the highest; the order is ethyl acetate, toluene; in the organic solvent having high polarity, the monomer The "Examples 10 to 12" were generated faster. That is, a 2-cyanoacrylate polycondensate of ethyl, isobutyl or ethoxyethyl group can also be used for depolymerization to form a monomer product (Examples 13 to 15). In the case of the original depolymerization method in which no basic substance is added, under normal pressure conditions, depolymerization cannot be carried out at 25 ° C, and the monomer cannot produce "Comparative Example 2"; at 200 ° C, although monomeric substances are formed, However, if the heating time is prolonged, the polymerization due to heat in the system also occurs at the same time, and the maximum concentration of the monomer is 26%; further, the depolymerization composition is very unstable due to heat, and the monomer is rapidly polymerized at room temperature. Also disappeared "Comparative Examples 3, 4".

[4] Method for producing purified 2-cyanoacrylate (salt) monomer * Example 22 In the 115.2 g of the depolymerized composition obtained in Example 1, phosphorus pentaoxide was added to 149.8 mg of p-benzoate. 576.0 mg of hydroquinone was distilled to obtain a purified ethyl-2-cyanoacylate monomer (hereinafter referred to as "fine monomer") 58.6 g. The generation rate of the fine monomer is calculated based on the following mathematical formula (4); the monomer concentration is based on the proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) measurement, and is the same as the mathematical formula (3). The calculation method is based on the basis. The results are shown in Table 2.

Fine monomer formation rate = amount of fine monomer [g] / 2-cyanoacrylate polycondensate [g] r100 (%) (4)

* Example 23 Using the depolymerized composition obtained in Example 2, except that in the same manner as in Example 22, 59.2 g of a fine monomer was obtained.

*Example 24 Using the depolymerized composition obtained in Example 13, except that in the same manner as in Example 22, 61.7 g of a fine monomer was obtained.

【Table 2】

According to the results of Table 2, the monomer concentration of the monomer obtained after the depolymerization composition was distilled showed a high value of 99.7% or more, and the fine monomer formation rate also showed the monomer in the depolymerized composition. The value of the substance concentration hardly changed "Examples 22 to 24". [Probable application of industry]

According to the present invention, since 2-cyanoacrylate (salt) monomer having few impurity components can be produced at a low temperature and for a short period of time, it is an industrially useful 2-cyanoacrylate (salt). Production method.

Claims (13)

A method for producing 2-cyanoacylate comprising: adding a basic substance to a solution of a polycondensate of a cyanoacetic ester and a formaldehyde to cause the polycondensation The working procedure for the depolymerization of the material is a method for producing the 2-cyanoacrylate. The method for producing 2-cyanoacrylate (salt) according to the first aspect of the invention, comprising: a neutralization operation procedure for adding an acid to the depolymerization reaction solution obtained by the depolymerization operation procedure, and The removal operation procedure of the salt generated by the aforementioned neutralization operation program. The method for producing 2-cyanoacrylate (salt) according to the first or second aspect of the invention, wherein the amount of the basic substance added is alkaline with respect to the cyanoacrylate unit of the polycondensate. The amount of the substance is 0.001 to 5 times the molar equivalent. The method for producing 2-cyanoacrylate (salt) according to any one of claims 1 to 3, wherein the amount of the basic substance added is relative to the cyanoacrylate of the polycondensate The unit, the basic substance is 0.1 to 3 times the molar equivalent amount. The method for producing 2-cyanoacrylate (salt) according to any one of claims 1 to 4, wherein the alkaline substance has a basic dissociation constant (pKb) of 6 or less. The method for producing a 2-cyanoacrylate according to any one of the preceding claims, wherein the alkaline substance is selected from the group consisting of an amine, a phosphine, and a sulfur. Thioxide, alkoxide, quaternary ammonium salt, and oxides, hydroxides, carbonates, phosphates, silicates of alkali metals and/or alkaline earth metals At least one of the groups. The method for producing 2-cyanoacrylate (salt) according to any one of claims 1 to 6, wherein the polycondensate has a weight average molecular weight of 1,000 to 10,000. The method for producing a 2-cyanoacrylate according to any one of the preceding claims, wherein the solvent of the solution of the polycondensate is selected from the group consisting of ethers and ketones. At least one of a group of ketones and/or esters. The method for producing 2-cyanoacrylate (salt) according to any one of claims 2 to 8, wherein the acid added to the depolymerization reaction solution is selected from the group consisting of inorganic acids and sulphur. At least one of a group of acids and acid chlorides. The method for producing 2-cyanoacrylate (salt) according to any one of claims 2 to 9, wherein the basic substance is an amine, and further, in the above-mentioned depolymerization reaction solution The acid sulfonic acid added. The method for producing a 2-cyanoacrylate according to any one of claims 2 to 10, wherein the alkaline substance is piperidine, and the depolymerization reaction solution The acid methane sulfonic acid added in the medium. The method for producing 2-cyanoacrylate (salt) according to any one of the items 1 to 11, wherein the temperature of the depolymerization operation program is 0 to 130 °C. The method for producing 2-cyanoacrylate (salt) according to any one of claims 1 to 12, further comprising a distillation operation procedure.