KR850001087B1 - Process for the preparation of 2-cyanoacrylates - Google Patents

Abstract

2-Cyano acrylate(I), used as a fast adhesive, is prepared from a chemical compd., having the formula NC-CH2-COO-R1-OR2-O-R3, using a reaction with formaldehyde or para formaldehyde; where R1 = C2-C4 1,2-alkylene gp.; R2 = C2-C4 alkylene gp.; and R3 = C1 - C6 alkylene gp. Suitable catalysts for the condensation reaction are piperidine, diethyl amine, dibutyl amine, morpholine, KOH, NaOH, sodium alkoxide, or a secondary amine salt in the reaction solvent such as benzene, toluene, xylene, trichloroethylene, methyl chloroform, tetrahydrofuran, ethanol, butanol, or water.

Description

Method for preparing 2-cyanoacrylate

The present invention relates to a method for preparing 2-cyanoacrylate.

Conventionally, alkyl 2-cyanoacrylate monomers have been widely used for joining metals, plastics, rubbers, woods, ceramics, etc. as a room temperature hardening one-part type instant adhesive agent which anionically polymerizes with moisture adsorbed on the surface of the adherend. .

However, in the case of bonding rubber, leather, paper, cloth, fiber and the like, since the cured product (polymer) of alkyl-2-cyanoacrylate is very hard, there is a defect in that the joint is hard and the flexibility is insufficient.

Thus, in order to soften the cured product of the alkyl 2-cyanoacrylate-based adhesive, a method of adding rubber fine particles, or adding a plasticizer or a thickener has been proposed, but by these methods, an adhesive portion rich in flexibility can be obtained. I could not. It is inferred in the case of alkyl acrylate polymers to improve the flowability of the cured adhesive by changing the kind of the alcohol moiety of 2-cyanoacrylate. In other words, the higher the alcoholic portion of the alkyl acrylate, the more flexible the polymer is produced, and among these, the n-octyl acrylate polymer is known to be the most flexible polymer. Applying this idea to alkyl 2-cyanoacrylate and examining the properties of the higher-alcohol 2-cyanoacrylate polymer, it was not a flexible polymer, but rather a brittle polymer. That is, the alkyl 2-cyanoacrylate polymer is a polymer of 1,1-disubstituted vinyl compound, and its substituent is a very rigid linear polymer because it is a highly polar nitrile group and a carboxyl group, and introduces a higher alkyl group into the polymer side chain. It does not seem to be flexible enough. The same applies to the use of paints, coating agents, flame retardants, binders and the like.

The present inventors conducted extensive research on the conventional method of modifying the rigid 2-cyanoacrylate described above to obtain a flexible cured product. As a result, the hardened | cured material obtained from 2-cyanoacrylate by introducing into the side chain of a polymer the group which has affinity with the main chain structure of the hardened | cured material of 2-cyanoacrylate which is a rigid 1, 1-disubstituted vinyl polymer, and has a plasticizing effect The present invention has been completed successfully by obtaining a flexible material.

According to the present invention there is provided a 2-cyanoacrylate represented by the following general formula (I):

Wherein R ¹ is a 1,2-alkylene group having 2 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, and R ³ is an alkyl group having 1 to 6 carbon atoms being).

According to the present invention, a stabilizer and a mixture of 2-cyanoacrylate represented by the general formula (I) or the 2-cyanoacrylate and other 2-cyanoacrylate monomer represented by the following general formula (II) There is also provided a curing composition which is formulated with a.

(Wherein R ⁴ is an alkyl, alkenyl group, alkynyl group, cycloalkyl group, aryl group, aralkyl group or alkoxyalkyl group having 1 to 12 carbon atoms, the alkyl, alkenyl, alkynyl, cycloalkyl, allyl and The aralkyl group may optionally have a halogen substituent or an ether bond, and the alkoxyalkyl group may have a halogen substituent.)

Examples of groups represented by R ⁴ include methyl, n-ethylpropyl, isopropyl, n-butyl, isobutyl, pentyl, hexyl, methoxyethyl, ethoxyethyl, butyloxyethyl, methoxypropyl, methoxybutyl And tetrahydrofurfuryl, allyl, propargylcyclohexyl, benzyl, 2-chloroethyl, trifluoroethyl and the like. As the other 2-cyanoacrylate monomer mentioned above, all the 2-cyanoacrylates generally known can be used.

When the composition for curing according to the present invention is cured by anionic polymerization with moisture, it can be used as an adhesive. When anionic polymerization initiator or radical polymerization initiator is present in the composition, it can be used as a coating material, various coating agents and molding materials. Can be used.

In this case, the following polymer is formed and hardened | cured.

Conventionally, 2-cyanoacrylate is reacted with cyanoacetate and formaldehyde in the presence of a basic catalyst such as secondary amine, sodium alkoxide to prepare a condensate having a condensation degree of 5 to 50, and then P ₂ It has been prepared by thermally polymerizing at 150 to 200 ° C in the presence of O ₅ or the like. 2-cyanoacrylate represented by the general formula (I) of the present invention can also be produced by conventional and yarn-producing methods.

Cyanoacetate used as a raw material in the present invention is obtained by esterification of cyanoacetic acid with an alcohol or transesterification of an alkylcyanoacetate with an alcohol as shown in the following reaction process formula.

Specific examples of the alcohol represented by HO-R ¹ -OR ² -OR ³ used in the present invention include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol mono Pentyl ether, diethylene glycol monohexyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monopentyl ether, dipropylene glycol monohexyl Ether, dibutylene glycol monomethyl ether, dibutylene glycol monoethyl ether, dibutylene glycol monobutyl ether, mono (3-methoxypropyl) -ethylene glycol, mono (3-methoxybutyl) -ethylene glycol, Mono (3-methoxypropyl) -propylene-1. 2-glycol, mono (3-methoxybutyl) -propylene-1, 2-glycol, mono (methoxyethyl) -propylene-1, 2-glycol, mono (methoxyethyl) -butylene-1, 2 -Glycols and the like.

The cyanoacetate esters of the above-mentioned alcohols and formaldehyde or paraformaldehyde are condensed in the presence of a catalyst in a molar ratio of 0.5 to 1.5: 1 [preferably 0.8 to 1.2: 1] to obtain a condensate. The catalyst is a base or amine with piperidine, diethylamine, dibutylamine, morpholine, KOH, NaOH, sodium alkoxide, secondary amine salt, etc., from 0.001 to 10 [preferably 0.01 to 10] for cyanoacetate. 1] It is used in mol%. Benzene toluene, xylene, trichloroethylene, methylchloroform, tetrahydrofuran, ethanol, butanol, water and the like are used as the reaction solvent. When the reaction is carried out at 20 to 150 ° C. [preferably 50 to 130 ° C.], condensates having a condensation degree of about 5 to 50 are obtained with the condensation water.

The condensation reaction mixture is then subjected to depolymerization either directly or after removal of the condensation catalyst, which is carried out at a temperature of 140 to 250 ° C. and 0.1 to 50 mmHg pressure in the presence of 0.01 to 10% by weight of phosphorus pentoxide, phosphoric acid and condensed phosphoric acid. Perform. Crude cyanoacrylate obtained by depolymerization is distilled again to obtain a high purity cyanoacrylate according to the present invention.

The condensation reaction and depolymerization reaction can be represented by the following reaction process formula.

The novel 2-cyanoacrylate according to the present invention thus obtained is represented by the general formula (I) as a monomer having high purity and low or medium viscosity.

The 2-cyanoacrylate according to the present invention is a novel compound, capable of anionic polymerization with a small amount of water, amine, alkali, and the like, or radical polymerization with a peroxide or azo compound, and a conventional alkyl 2-cyanoacrylate. It can manufacture by the method similar to a manufacturing method.

Typical implementations of 2-cyanoacrylate represented by formula (I) are as follows.

2- (2'-methoxy) -ethoxyethyl-2 "-cyanoacrylate,

2- (2'-ethoxy) -ethoxyethyl-2 "-cyanoacrylate,

2- (2'-propyloxy) -ethoxyethyl-2 "-cyanoacrylate,

2- (2'-butoxy) -ethoxyethyl-2 "-cyanoacrylate,

2- (2'-pentyloxy) -ethoxyethyl-2 "-cyanoacrylate,

2- (2'-hexyloxy) -ethoxyethyl-2 "-cyanoacrylate,

2- (2'-methoxy) -propyloxypropyl-2 "-cyanoacrylate,

2- (2'-ethoxy) -propyloxypropyl-2 "-cyanoacrylate,

2- (2'-propyloxy) -propyloxypropyl-2 "-cyanoacrylate,

2- (2'-butyloxy) -propyloxypropyl-2 "-cyanoacrylate,

2- (2'-pentyloxy) -propyloxypropyl-2 "-cyanoacrylate,

2- (2'-hexyloxy) -propyloxypropyl-2 "-cyanoacrylate,

2- (2'-methoxy) -butyloxybutyl-2 "-cyanoacrylate,

2- (2'-ethoxy) -butyloxybutyl-2 "-cyanoacrylate,

2- (2'-butyloxy) -butyloxybutyl-2 "-cyanoacrylate,

2- (2'-methoxy) -propyloxybutyl-2 "-cyanoacrylate,

2- (2'-methoxy) -butyloxybutyl-2 "-cyanoacrylate,

2- (2'-methoxy) -propyloxypropyl-2 "-cyanoacrylate,

2- (2'-methoxy) -butyloxybutyl-2 "-cyanoacrylate,

2- (2'-methoxy) -ethoxypropyl-2 "-cyanoacrylate,

2- (2'-methoxy) -ethoxybutyl-2 "-cyanoacrylate,

The novel 2-cyanoacrylate represented by the general formula (I) according to the present invention has two ether bonds (-COC-) in the alcohol moiety of the ester, and the alkyl is directly bonded to the 2-cyanoacryloyl group. The rene group [R ¹ of the general formula (I)] is characterized by being an ethylene group, a propylene group or a butylene group bonded to adjacent ether bonds in the 1 and 2 positions. Such 2-cyanoacrylate is effective as an adhesive because of its ease of synthesis, high purity, and good storage stability. In terms of production and practical use, in general formula (I), R ² is an alkylene group having 2 to 4 carbon atoms (in this case, the alkylene group is 1, 2-, 1, 3- or 1, 4-one), Preference is given to 2-cyanoacrylates in which R ³ is an alkyl group having 1 to 6 carbon atoms.

When the novel 2-cyanoacrylate represented by the general formula (I) according to the present invention is used in the preparation of a curing composition used as a scavenger, etc., it is hydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol as a stabilizer. , Phenol, bisphenol A, anisole, 2, 6-di-tert-butyl phenol (BHT), sulfurous acid (SO ₂ ), p-toluenesulfonic acid, methanesulfonic acid, benzenesulfonic acid, trifluoro methanesulfonic acid, trifluoroacetic acid , At least one component selected from carbon dioxide gas, thionyl chloride and propanesultone is added in an amount of 1 to 10,000 ppm (preferably 10 to 1,000) by weight.

As a composition having a high viscosity, a curing composition according to the present invention may be used, for example, an alkyl acrylate polymer such as polyacrylate, alkyl acrylate and vinyl acetate, styrene, butadiene, acrylic acid, methacrylic acid, acrylonitrile, Copolymers with methacrylonitrile, glycidyl methacrylate and the like, alkyl methacrylate polymers, such as polyalkyl methacrylates, alkyl methacrylates and vinyl acetate, styrene butadiene, acrylic acid, methacrylic acid, acrylonitrile And polymers such as copolymers with methacrylonitrile, glycidyl methacrylate, alkylcyanoacrylate polymers acetyl cellulose, polystyrene and the like can be obtained in the composition. Generally, adhesives having a viscosity of 1 to 10,000 cps are effectively used.

Moreover, you may add a plasticizer as needed. For example, the flexible cured product may be prepared by adding dioctylphthalate, dibutyl phthalate, trioctyl trimellitate, dioctyl adipate, dioctyl glutarate and the like in an amount of 0 to 50% by weight based on the weight of 2-cyanoacrylate. You can get

In addition, as the filler, fine particles such as silica, alumina, silica-alumina, boron nitride, polyethylene, and teflon can be added to increase bonding strength and adhesion. In order to obtain such an effect, fine particles having a particle size of 0.001 to 100 mu are added in an amount of 1 to 30% by weight based on the weight of 2-cyanoacrylate.

If necessary, dyes or pigments can be added, and fragrances may be added to give aroma. When the curing composition adhesive composed of 2-cyanoacrylate represented by the general formula (I) according to the present invention is used on the surface of the adherend, anion polymerization occurs by a small amount of water absorbed on the surface of the adherend. Since it hardens | cures, the bonding effect similar to the conventional alkyl 2-cyanoacrylates is obtained. However, unlike conventional 2-cyanoacrylate adhesives, this adhesive is effective for bonding flexible materials such as leather, vinyl sheets, rubber, fibers, paper, etc., because it is a flexible curing adhesive. In other words, the cured product and the flap around have the same flexible advantages as the adherend.

Moreover, the intensity | strength can be increased by adding the conventional 2-cyanoacrylate represented by general formula (II) to the 2-cyanoacryl represented by general formula (I). In general, the higher the mixing ratio of the novel 2-cyanoacrylate (I) according to the present invention, the greater the flexibility, and the higher the mixing ratio of the conventional 2-cyanoacrylate, the harder the hardened product. There is a tendency to lose. The mixing ratio of the novel 2-cyanoacrylate (I) of the present invention to the conventional 2-cyanoacrylate (II) is 1 to 100: 99 to 0 [preferably 30 to 100: 70 by weight]. ~ 0].

As described above, the novel 2-cyanoacrylate (I) of the present invention or a mixture of this and the conventional 2-cyanoacrylate (II) is subjected to anionic polymerization with a small amount of water, and also to the conventional alkyl 2- Like cyanoacrylates, anionic polymerization occurs by bases or weak bases such as amines, alkalis, phosphines, sulfides, mercaptans, quaternary ammonium salts, water, alcohols, and the like, and polymers having the following skeleton can be obtained.

The molecular weight of such a polymer is usually about 10,000 to 1 million.

As the initiator of the anionic polymerization, N, N-dimethylamyline, N, N-dimethyl-p-toluidine, sodium ethoxide, triethylbenzyl ammonium chloride and the like are particularly effective. The novel 2-cyanoacrylate (I) of the present invention is radically polymerized with a radical initiator to obtain a cured product having the above skeleton. As the initiator for radical polymerization according to the present invention, peroxides and azo compounds such as benzoyl peroxide and azobisisobutyronitrile are effective.

In addition, the polymerization can be carried out by ultraviolet rays and sunlight. In this case, the addition of a photosensitizer such as benzophenone, benzoin monomethyl ether, etc. facilitates photopolymerization.

The novel 2-cyanoacrylate (I) of the present invention is capable of radical copolymerization with all kinds of vinyl monomers.

The novel curing composition of the present invention is useful not only as an adhesive but also as a coating material and various coating materials, and also as a molding material or a potting agent.

The homopolymer and copolymer of 2-cyanoacrylate according to the present invention can also be used for paints, various coating agents, preservatives, binders and the like.

The present invention will be described in more detail by enumerating the following examples, and the present invention is not limited only to these examples. In addition, unless otherwise specified, all show weight% in an Example.

Example 1

85 parts of cyanoacetic acid, 161 parts of diethylene glycol monoethyl ether, 100 parts of toluene and 1 part of sulfuric acid were reacted under reflux, and the produced water was removed as an azeotrope with toluene. After completion of the reaction, the acid of the emi reaction was neutralized with sodium hydroxide, and then the oil phase was distilled off to obtain 2- (2'-ethoxy) -ethoxyethylcyanoacetate. The properties of the product are as follows.

bp = 120 ° C./2 mmHg, d ₄ ²⁰ = 1.098, n _D ²⁰ = 1.4448, yield 170 parts of 2-cyanoacrylate.

Next, 166 parts of 2- (2'-ethoxy) -ethoxyethylcyanoacetate, 24 parts of paraformaldehyde, 80 parts of toluene and 0.2 parts of piperidine were condensed under reflux for 7 hours while removing the generated water. . After washing the reaction mixture with an aqueous p-toluenesulfonic acid solution, the oil layer was separated, mixed with 0.7 parts and 0.5 parts of hydroquinone, and then 95 parts of depolymerized fraction was obtained under reduced pressure at 165 to 205 ° C. Distillation was carried out again to obtain 65 parts of 2- (2'-ethoxy) -ethoxyethyl-2 " -cyanoacrylate having a boiling point of 107 to 110 DEG C / 2mmHg. 21 ppm SO ₂ was added thereto, and the adhesive performance was investigated. The results are described below.

Curing time measured according to JIS K 6861-1977:

Iron / iron: 15 seconds

Rigid PVC / PVC: 10 seconds

ABS / ABS: 5 seconds

This monomer was subjected to anionic polymerization with N, N-dimethyl-p-toluidine to obtain a polymer. This polymer was transparent and had a glacial transition point (Tg) of −5 ° C. with flexibility.

Example 2

85 parts of cyanoacetic acid, 144 parts of diethylene glycol monoethyl ether, 1 part of sulfuric acid, and 100 parts of toluene were subjected to esterification under reflux while removing the produced water. Next, the unreacted acid was neutralized, and the mixture was distilled off to obtain 160 parts of 2- (2'-methoxy) -ethoxyethylcyanoacetate. The properties of this product are as follows:

bp = 120 ° C./3 mmHg, d ₄ ²⁰ = 1.132, n _D ²⁰ = 1.4426.

154 parts of 2- (2'-methoxy) -ethoxyethylcyanoacetate, 24 parts of paraformaldehyde, 80 parts of toluene and 0.2 parts of piperidine were subjected to condensation under reflux while removing the produced water by azeotropic distillation. It was. After washing the condensation mixture with water, the oil layer was mixed with 0.5 parts of P ₂ O _{5 and} 0.5 parts of hydroquinone, and then depolymerized to obtain 50 parts of a fraction having a boiling point of 100 to 148 ° C./5 mmHg. The product was distilled off again to obtain liquid 2- (2'-methoxy) -ethoxyethyl-2 "-cyanoacetate (boiling point: 100-112 DEG C / 3mmHg) having a viscosity of 20 to 30 cps. After the addition of ₂ 21 ppm, the adhesion performance was examined. The curing time for hard vinyl chloride was 10 seconds and the curing time for iron was 15 seconds.

Example 3

85 parts of cyanoacetic acid, 194 parts of diethylene glycol mono n-butyl ether, 100 parts of toluene, and 2 parts of p-toluenesulfonic acid were subjected to esterification under reflux while removing the produced water by azeotropic distillation to obtain 2- (2 ' 195 parts of -n-butyloxy) -ethoxyethylcyanoacetate were obtained. The properties of this product are as follows.

bp = 131-133 ° C. 2 mmHg, d ₄ ²⁰ = 1.053, n _D ²⁰ = 1.4442.

Next, 189 parts of 2- (2'-n-butyloxy) -ethoxyethylcyanoacetate, 24 parts of paraformaldehyde, 80 parts of toluene and 0.2 parts of piperidine were refluxed for 7 hours while removing the produced water. . The condensation reaction mixture was washed with 5% p-toluenesulfonic acid aqueous solution, the oil layer was separated, mixed with 0.5 parts of P ₂ O _{5 and} 0.5 parts of hydroquinone, and depolymerized under reduced pressure at 150 to 200 ° C. to obtain a boiling point of 130 to 152 ° C. 88 parts of fractions which were / 3mmHg were obtained. The fraction was distilled again to give 2- (2'-n-butyloxy) -ethoxyethyl-2 "-cyanoacrylate having a boiling point of 120 mm to 124 ° C. 3 mm Hg. The product was pale yellow with a viscosity of 20 to 30 cps. After adding 53 ppm of SO ₂ to it, the performance as an adhesive was examined. As a result, the curing time for hard polyvinyl chloride was 45 seconds, and the curing time for iron was 60 seconds.

Example 4

85 parts of cyanoacetic acid, 228 parts of diethylene glycol mono-n-hexyl ether, 1 part of p-toluenesulfonic acid and 150 parts of benzene were reacted under reflux while removing the produced water by azeotropic distillation. Next, the reaction mixture was neutralized and distilled to obtain 220 parts of 2- (2'-n-hexyloxy) -ethoxyethylcyanoacetate. The properties of this product are as follows.

bp = 152-145 C / 2 mm Hg, d ₄ ²⁰ = 1.022, n _D ²⁰ = 1.4465.

Next, 212 parts of 2- (2'-n-hexyloxy) -ethoxyethylcyanoacetate, 24 parts of paraformaldehyde, 80 parts of toluene and 0.2 parts of piperidine, while removing condensed water by azeotropic distillation After the reaction, the reaction product was subjected to reduced pressure depolymerization at 150 to 200 ° C. in the presence of 0.5 parts of P ₂ O _{5 and} 0.5 parts of hydroquinone to give 2-2′-n-hexyloxy) having a boiling point of 143 to 160 ° C./3 mmHg. Ethoxyethyl-2 "-cyanoacrylate was obtained.

After adding 50 ppm sulfurous acid gas, the performance as an adhesive was examined. As a result, the curing time for the hard polyvinyl chloride was 30 seconds, and the tensile shear bond strength was 75 kg / cm ² .

Example 5

85 parts of cyanoacetic acid, 178 parts of diethylene glycol monomethyl ether, 1 part of sulfuric acid and 100 parts of toluene were esterified under reflux while removing the produced water by azeotropic distillation, and then the reaction mixture was distilled off to obtain 2- (2 185 parts of -methoxy) -propyloxypropylcyano acetate were obtained. The properties of cyanoacetate are as follows:

bp = 115-118 ° C./2.5 mmHg, d ₄ ²⁰ = 1.060, n _D ²⁰ = 1.4368.

Next, 177 parts of 2- (2'-methoxy) -propyloxy-propylcyano acetate, 24 parts of paraformaldehyde, 80 parts of toluene and 0.2 parts of piperidine were removed under reflux while removing the produced water by azeotropic distillation. Reacted. Next, 0.5 part of P ₂ O _{5 and} 0.5 part of hydroquinone were added to the reaction product obtained above, and the reaction product was polymerized under reduced pressure at 150 to 200 ° C. to obtain 100 parts of a stroke having a boiling point of 110 to 130 ° C./3 mmHg. This fraction was distilled again to obtain 2- (2'-methoxy) -propyloxypropyl-2 "-cyanoacrylate having a boiling point of 103 to 105 占 폚 / 3mmHg.

After adding 34 ppm of sulfurous acid gas to the colorless liquid obtained above, the performance as an adhesive was examined. As a result, the curing time for hard vinyl chloride was 30 seconds, and the curing time for iron was 45 seconds.

Example 6

Next, a 2% N, N-dimethylformamide was added to the 2-cyanoacrylate monomer shown in Table 1 to prepare a homogeneous solution. This monomer was subjected to anionic polymerization, and cured at 40 to 60 ° C. for at least 12 hours to obtain a cured product having a molecular weight of 100,000 to 300,000 measured by high performance liquid chromatography in tetrahydrofuran. Other measurements of this cured product are shown in the following first table.

[Table 1]

As a control, anion polymerization was performed on ethyl 2-cyanoacrylate in the same manner as above to obtain a cured product. This cured product was hard and the Tg was 100 ° C.

Moreover, when the hardened | cured material of n-hexyl 2-cyanoacrylate was examined, it was a hard and fragile substance.

Example 7

0.1% azobisisobutyronitrile was added to each of the 2-cyanoacrylate monomers described in Table 1 above, degassed, and the monomers were subjected to radical polymerization at 60 ° C. for 24 hours to obtain a cured product. . The cured products obtained were all transparent and flexible.

Example 8

Dissolve 0.2% of benzophenone in 2- (2'-ethoxy) -ethoxyethyl-2 "-cyanoacrylate and irradiate the solution with ultraviolet light emitted from a high pressure mercury lamp in an inert gas atmosphere such as nitrogen gas. As a result, a transparent cured product rich in flexibility was obtained.

In addition, 20 g of 2- (2'-ethoxy) -ethoxyethyl-2 "-cyanoacrylate was injected into a 20-g polyethylene container, and the sunlight was irradiated. As a result, 2- ( A 2'-ethoxy) -ethoxyethyl-2 "-cyanoacrylate polymer was obtained, the properties of which were the same as in Example 7.

Example 9

2- (2'-ethoxy) -ethoxyethyl-2 "-cyanoacrylate (I) obtained in Example 2 was reacted with ethyl 2-cyanoacrylate (II) in the ratios listed in the following table. After the mixing, 50 ppm of sulfurous acid gas and 1,000 ppm of hydroquinone were added to prepare an adhesive, and the adhesive performance of the adhesive was measured to obtain the results shown in the following table.

[Table 2]

Reference: *: Measured according to JIS K 6861-1977

**: Measured by JIS K 6861-1977

Example 10

Using neoprene rubber as the flexible material, the two pieces of neoprene rubber are bonded to each other using the 2-cyanoacrylate adhesive described in Table 3 below, and the bond tensile shear strength of JIS K 6861-1977 is obtained. Measured. The results are shown in Table 3 below.

Test piece: Neoprene rubber: 3 × 25 × 100mm

Bonding area: 3.125cm ²

Bonding condition: 23 ± 1 ℃, 60 ± 2% RH, aging time 24 hours.

[Table 3]

Reference: ^* Material Breaking

Example 11

Esterification reaction with 85 parts of cyanoacetic acid and 2- (2'-ethoxy) -ethoxybutanol was carried out in the same manner as in Example 1 to 2- (2'-ethoxy) -ethoxybutylcyanoacetate Was synthesized. The properties of this composite are as follows:

bp = 130 ~ 135 ° C / 2.5mmHg, d ₄ ²⁰ = 1.05

Next, 189 parts of 2- (2'-ethoxy) -ethoxybutyl cyanoacetate, 24 parts of paraformaldehyde, 80 parts of toluene, and 0.2 parts of piperidine are condensates obtained by condensation in the same manner as in Example 1. Was depolymerized to obtain 70 parts of a stroke having a boiling point of 135 to 150 ° C / 3mmHg. This fraction was distilled again to obtain 2- (2'-ethoxy) -ethoxybutyl-2 "-cyanoacrylate with a boiling point of 122-125 degreeC / 3mmHg.

In the adhesive obtained by adding 50 ppm of sulfurous acid gas, the curing time of hard polyvinyl chloride exceeded 45 seconds, and a flexible cured product was obtained.

Claims (1)

General formula

A method of preparing 2-cyanoacrylate of the following general formula (I) by reacting a compound of with formaldehyde or para formaldehyde and then depolymerizing the resulting condensate.

In the general formula, R ¹ is a 1, 2-alkylene group having 2 to 4 carbon atoms, R ² is an alkylene group having 2 to 4 carbon atoms, and R ³ is an alkyl having 1 to 6 carbon atoms It's Rengi.