JPH06128212A - 2-cyanoacrylate - Google Patents

Abstract

PURPOSE:To obtain a 2-cyanoacrylate having instant adhesiveness and bond strength especially even under high temperatures without causing a whitening phenomenon resulting from vaporization after application and emitting an irritating smell in the case of using the 2-cyanoacrylate as a raw material for an instant adhesive. CONSTITUTION:A 2-cyanoacrylate of the formula CH2=C(C)-CO2-R1-R2 (R1 is 1-6C alkylene; R2 is cyclohexyl). A cold-setting instant adhesive having less whitening phenomenon and irritating smell, showing high instant adhesiveness and high bond strength especially at high temperature is obtained and is used more widely than the existing instant adhesive. A polymer comprising the 2- cyanoacrylate as a component is used as a coating agent or a binder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel 2-cyanoacrylate used for instant adhesives, coating agents, etc., and is widely used in various industrial fields.

[0002]

_2. Description of the Related Art 2-Cyanoacrylate represented by the following general formula CH ₂ ═C (CN) -CO ₂ -R is widely used as a main component of an instant adhesive, and a small amount of it on the surface of an adherend. It rapidly undergoes anionic polymerization with water, and can adhere the adherend with an extremely high adhesive force. Known 2-cyanoacrylates include alkyl 2-cyanoacrylates such as methyl 2-cyanoacrylate, ethyl 2-cyanoacrylate, isopropyl 2-cyanoacrylate and isobutyl 2-cyanoacrylate, cyclopentyl 2-cyanoacrylate, cyclohexyl. 2-Cyroalkyl 2-cyanoacrylate such as 2-cyanoacrylate, cycloheptyl 2-cyanoacrylate, allyl 2-cyanoacrylate, propargyl 2-cyanoacrylate, benzyl 2-cyanoacrylate or the like having an unsaturated group or an aromatic group 2- Cyanoacrylate, 2-chloroethyl 2-cyanoacrylate, 2,2,2-trifluoroethyl 2-cyanoacrylate, 2- (2,2,2-trifluoroethoxy) ethyl
2-cyanoacrylate having halogen such as 2-cyanoacrylate, 2-methoxyethyl 2-cyanoacrylate,
Examples thereof include alkoxyalkyl 2-cyanoacrylate such as 2-ethoxyethyl 2-cyanoacrylate.

[0003]

However, when these 2-cyanoacrylates are used as an adhesive component, the 2-cyanoacrylate before polymerization volatilizes and re-adheres while polymerizing around the adhesive part. Occurs, and as a result, there arises a problem that the vicinity of the adhesion site of the adherend is whitened. In addition, the pungent odor caused by volatilized 2-cyanoacrylate is often a problem. In order to solve this problem, it is generally practiced to increase the alkyl group in the ester part, but this method can reduce the whitening phenomenon and irritating odor. There is a strong fear that it will decrease.

Further, although the 2-cyanoacrylate adhesive generally has high instantaneous adhesiveness and adhesive strength, it has low heat resistance and the temperature at which the adhesive strength can be practically maintained is 80.
Up to ℃. As a method of improving heat resistance, allyl 2-
A method of copolymerizing methyl methacrylate and diallyl itaconate using cyanoacrylate as a base monomer (Japanese Patent Publication No. 55-45590), a method of adding a sulfone compound and a dicarboxylic acid anhydride to 2-cyanoacrylate (Japanese Patent Publication No. 61-8112), Method of adding cyanuric halide to 2-cyanoacrylate (Japanese Patent Publication No. 1-4378)
9), 2-cyanoacrylate to 1-cyanobutadiene-1,3
-Method of adding carboxylic acid polyester (Japanese Patent Publication No. 2-
57835), a method using silicon-containing 2-cyanoacrylate (JP-A-4-8780), a method using neopentyl 2-cyanoacrylate (JP-A-4-91069), and the like. However, under the present circumstances, the performances such as heat resistance and instant adhesiveness are not sufficient.

[0005]

In order to solve the above-mentioned problems, the present inventors have synthesized various 2-cyanoacrylates, and a specific novel cyclohexylalkyl 2-cyanoacrylate has been proposed to solve these problems. The present invention has been completed by finding that the above can be solved.

That is, the present invention is represented by the following general formula.
It relates to 2-cyanoacrylate. _{CH 2 = C (CN) -CO} 2 -R 1 -R 2 ( where, R ₁ represents an alkylene group having 1 to 6 carbon atoms, R ₂ represents a cyclohexyl group)

The present invention relates to a novel 2-cyanoacrylate represented by the above general formula, and specific compounds include cyclohexylmethyl 2-cyanoacrylate, 2-cyclohexylethyl 2-cyanoacrylate, 1-
Cyclohexylethyl 2-cyanoacrylate, 3-cyclohexylpropyl 2-cyanoacrylate, 2-cyclohexylpropyl 2-cyanoacrylate, 1-cyclohexylpropyl 2-cyanoacrylate, 4-cyclohexylbutyl 2-cyanoacrylate, 5-cyclohexylpentyl 2-
Examples thereof include cyanoacrylate and 6-cyclohexylhexyl 2-cyanoacrylate.

The 2-cyanoacrylate of the present invention is a known 2-cyanoacrylate.
Similar to the method for producing cyanoacrylate, the corresponding cyanoacetate and paraformaldehyde or formaldehyde are dehydrated and condensed in the presence of a basic catalyst to produce a condensate, and then the condensate is heated to depolymerize. Can be easily obtained.

The novel 2-cyanoacrylate of the present invention is an unstable compound which is easily polymerized by water present in the air or on the surface of the substance, but it should be stably used by adding an appropriate polymerization inhibitor. You can

That is, at least one of anionic polymerization inhibitors such as sulfur dioxide, organic sulfonic acids, carboxylic acids and boron trifluoride, and hydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol, 2,6-di-tert- It can be stably used by adding at least one kind of radical polymerization inhibitor such as butylphenol.

The appropriate addition amount of such a polymerization inhibitor varies somewhat depending on the kind of each polymerization inhibitor, but generally it is preferably in the range of 1 to 10000 ppm, respectively.

The novel 2-cyanoacrylate of the present invention can be used alone as a raw material for instant adhesives, but can also be used in combination with a known 2-cyanoacrylate. Well-known that can be used by mixing
As 2-cyanoacrylate, methyl 2-cyanoacrylate, ethyl 2-cyanoacrylate, propyl 2-cyanoacrylate, isopropyl 2-cyanoacrylate, butyl 2-cyanoacrylate, isobutyl 2-cyanoacrylate, pentyl 2-cyanoacrylate, hexyl 2 -Cyanoacrylate, cyclohexyl 2-cyanoacrylate, 2-methoxyethyl 2-cyanoacrylate, 2-ethoxyethyl 2-cyanoacrylate, allyl 2-cyanoacrylate and the like can be mentioned.

When the known 2-cyanoacrylate is mixed, it is preferable to mix the known 2-cyanoacrylate in such an amount that the characteristics of the novel 2-cyanoacrylate of the present invention are not impaired. % Or less is preferable.

In order to further improve heat resistance and durability, a cross-linking agent in which both ends of alkylene glycol are ester of 2-cyanoacrylic acid or 2-cyano-2,4-pentadienoic acid is added. You can also

When the novel 2-cyanoacrylate of the present invention is used alone or in combination with a known 2-cyanoacrylate as an instant adhesive, polymethacrylic acid can be used when high viscosity is required. Ester, cellulose acetate, diallyl phthalate prepolymer and the like can be used as a thickener. Further, when coloring is required, a dye or the like can be added.

Further, the novel 2-cyanoacrylate of the present invention, by itself or by radical polymerization or anionic polymerization of a mixture with other vinyl monomers, is converted into a homopolymer or copolymer and dissolved in a solvent. Can be used as a coating agent or binder.

[0017]

The 2-cyanoacrylate of the present invention, when used as a raw material for an adhesive and applied to an adherend, does not cause a whitening phenomenon due to polymerization after volatilization, and does not emit an irritating odor. The adhesiveness and the adhesive strength, especially the adhesive strength at high temperature, also show excellent effects.

[0018]

The present invention will be described below with reference to examples.
The present invention is not limited to this.

Example 1 Synthesis of cyclohexylmethyl 2-cyanoacrylate 300 g of cyclohexylmethanol and 222 g of cyanoacetic acid were placed in a three-necked flask equipped with a stirrer, thermometer and water separator.
Toluene (249 ml) and p-toluenesulfonic acid (9.5 g) were charged, and the resulting water was azeotropically distilled off while heating under reflux.
The reaction was allowed for 0 hours. After neutralizing with 500 ml of 10% NaHCO ₃ aqueous solution, Na ₂ SO ₄ was added to the organic layer for drying.
After filtration, desolvation was performed under reduced pressure, and then distillation was performed to obtain 318 g (yield 67%) of cyclohexylmethylcyanoacetate having a boiling point of 119 to 124 ° C./4 mmHg. A 4-necked flask equipped with a stirrer, a thermometer, a water separator, and a dropping funnel was charged with 24.3 g of paraformaldehyde, 80 ml of toluene, and 0.16 ml of piperidine, heated to 80 ° C., and then 153 g of cyclohexylmethylcyanoacetate at the same temperature. Was added from a dropping funnel. The mixture was heated to reflux and reacted for 18 hours while azeotropically removing water produced by the condensation reaction to obtain a viscous yellowish brown liquid. After removing toluene under normal pressure, 4.9 g of phosphorus pentoxide and 1.2 g of hydroquinone were added and mixed well. After the desolvation under reduced pressure, the mixture was heated to 175 to 200 ° C. under reduced pressure of 4 mmHg for depolymerization to obtain 76 g of a fraction at 108 to 130 ° C. This fraction was distilled in the presence of a small amount of phosphorus pentoxide and hydroquinone to give 58 g (yield 37%) of a compound having a boiling point of 113 to 118 ° C./5 mmHg, which was confirmed by cyclohexylmethyl 2-cyanoacrylate from ¹ H-NMR spectrum. I confirmed that there is. The chemical shifts of NMR are shown below, and the chart is shown in FIG. ¹ H-NMR spectrum (100 MHz, CDCl ₃ / T
MS) δ: 7.02 ppm (s, 1H, (* a)) δ: 6.59 ppm (s, 1H, (* a)) δ: 4.08 ppm (d, J = 8.4 Hz, 2H, (*
b)) δ: 0.60 to 2.00 ppm (m, 11H, (* c)) CH ₂ ^{(* a)} = C (CN) -CO ₂ -CH ₂ ^{(* b)} -C ₆ H ₁₁ ^{(* c)}

Example 2 Synthesis of 2-cyclohexylethyl 2-cyanoacrylate In a three-necked flask equipped with a stirrer, thermometer, and water separator, 2-cyclohexylethanol (456 g) and cyanoacetic acid (303) were added.
g, toluene 356 ml, p-toluenesulfonic acid 13.5 g
Was charged, and the reaction was carried out for 7 hours while heating and refluxing the generated water by azeotropic removal. 10% NaHCO ₃ aqueous solution 890
After neutralizing with ml, Na ₂ SO ₄ was added to the organic layer for drying. After filtration, desolvation was carried out under reduced pressure, followed by distillation to obtain 445 g of 2-cyclohexylethyl cyanoacetate having a boiling point of 131 to 142 ° C / 4 mmHg (yield 40%).
Obtained. A four-necked flask equipped with a stirrer, a thermometer, a water separator, and a dropping funnel was charged with 31.5 g of paraformaldehyde, 105 ml of toluene, and 0.22 ml of piperidine, heated to 80 ° C, and then heated to 2-cyclohexylethylcyano at the same temperature. 215 g of acetate was added from a dropping funnel. The mixture was heated to reflux and reacted for 14 hours while azeotropically removing water produced by the condensation reaction to obtain a viscous yellowish brown liquid. After removing toluene under normal pressure, 6.3 g of polyphosphoric acid and 1.6 g of hydroquinone were added and mixed sufficiently. Subsequent to vacuum dewatering, heating was performed at 185 to 210 ° C. under reduced pressure of 5 mmHg for depolymerization to obtain 130 g of a distillate at 126 to 130 ° C. This fraction was distilled in the presence of a small amount of polyphosphoric acid and hydroquinone to give 87 g of a compound having a boiling point of 111 to 122 ° C / 3 mmHg.
(Yield 40%) was obtained, and it was confirmed from ¹ H-NMR spectrum that it was 2-cyclohexylethyl 2-cyanoacrylate. The chemical shifts of NMR are shown below, and the chart is shown in FIG. ¹ H-NMR spectrum (100 MHz, CDCl ₃ / T
MS) δ: 7.00 ppm (s, 1H, (* a)) δ: 6.57 ppm (s, 1H, (* a)) δ: 4.29 ppm (t, J = 9.4 Hz, 2H, (*
b)) δ: 0.52 to 1.96 ppm (m, 13H), (* c) and (* d)) CH ₂ ^{(* a)} = C (CN) -CO ₂ -CH ₂ ^{(* b)} - CH ₂ ^{(* c)} −
C ₆ H ₁₁ ^{(* d)}

Application Example 1 Cyclohexylmethyl 2-cyanoacrylate obtained in Example 1 was mixed with 40 ppm of sulfur dioxide and 200 pp of hydroquinone.
When m was added to form an adhesive and the set time of hard vinyl chloride was measured according to JIS-K-6861, it was 2
It was 0 seconds. The tensile shear bond strength of iron was measured and found to be 110 kgf / cm ² . Furthermore, 120 ℃
The tensile shear bond strength of iron under heating after heating for 1 hour was 100 kgf / cm ² .

Application Example 2 2-Cyclohexylethyl 2-cyanoacrylate obtained in Example 2 was mixed with 40 ppm of sulfur dioxide and 20 parts of hydroquinone.
Add 0ppm to make an adhesive, JIS-K-6861
When the set time of the hard vinyl chloride was measured according to the above, it was 30 seconds. The tensile shear bond strength of iron was measured and found to be 100 kgf / cm ² . Furthermore, 1
When the tensile shear bond strength of iron under heating after heating at 20 ° C. for 1 hour was measured, it was 90 kgf / cm ² .

Comparative Application Example 1 Regarding a commercially available ethyl 2-cyanoacrylate adhesive,
When the set time of the hard vinyl chloride was measured according to JIS-K-6861, it was 5 seconds. The tensile shear bond strength of iron was measured and found to be 140 kgf / cm ² . Further, the tensile shear bond strength of iron under heating after heating at 120 ° C. for 1 hour was 40 kgf / cm ² .

Application Example 3 In order to investigate the whitening phenomenon, a drop of the adhesive of Application Example 1 was dropped into a dish that had been cleaned beforehand. Similarly, the adhesives of Application Example 2 and Comparative Application Example 1 were dropped in another petri dish. When left at 23 ° C. and 50% RH for 24 hours, the commercially available adhesive of Comparative Application Example 1 turned the entire glass surface of the petri dish white, but Application Example 1 and Application Example 2
No whitening phenomenon was observed with the adhesive of No. Also,
When the odors of the three adhesives were compared, a strong pungent odor was felt with the commercially available adhesive of Comparative Application Example 1, but almost no odor was found with the adhesives of Application Example 1 and Application Example 2.

[0025]

EFFECTS OF THE INVENTION By using the novel 2-cyanoacrylate of the present invention, a room temperature curable instant adhesive having little whitening phenomenon and irritating odor and having high instant adhesiveness, adhesive strength and adhesive strength under heating is obtained. Therefore, it can be used more widely than conventional 2-cyanoacrylate instant adhesives. Further, the novel polymer containing 2-cyanoacrylate of the present invention can be used as a coating agent or a binder. Therefore, the role of the present invention widely in the industrial world is extremely large.

[Brief description of drawings]

1 is an NMR chart of cyclohexylmethyl 2-cyanoacrylate obtained in Example 1. FIG.

2 is an NMR chart of 2-cyclohexylethyl 2-cyanoacrylate obtained in Example 2. FIG.

Claims (1)

[Claims] 1. A 2-cyanoacrylate represented by the following general formula. _{CH 2 = C (CN) -CO} 2 -R 1 -R 2 ( where, R ₁ represents an alkylene group having 1 to 6 carbon atoms, R ₂ represents a cyclohexyl group)