JPH06192202A - 2-cyanoacrylate - Google Patents

Abstract

PURPOSE:To obtain a 2-cyanoacrylate, used as a raw material for adhesives without causing a whitening phenomenon due to polymerization following vaporizing when applied to a material to be adhered and without emitting irritant smell and capable of manifesting excellent action on both instantaneous adhesion and adhesive strength. CONSTITUTION:The 2-cyanoacrylate of the formula CH2=C(CN)-CO2-R-C6H5 (R is 2-6C alkylene), e.g. 2-phenylethyl 2-cyanoacrylate. The 2-cyanoacrylate of the formula is readily obtained by subjecting the corresponding cyanoacetate and paraformaldehyde or formaldehyde to dehydrating condensation in the presence of a basic catalyst, providing a condensate, then heating and depolymerizing the resultant condensate. An instantaneous adhesive obtained from this compound of the formula has curability at ordinary temperature with a high adhesive strength. A polymer containing the compound of the formula 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 trace amount on the surface of an adherend. The water content causes rapid anionic polymerization, and the adherend can be bonded with an extremely strong 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. As a method for solving this problem, it is generally considered to increase the alkyl group in the ester part, but it is possible to reduce the whitening phenomenon and irritating odor with this method, but at the same time There is a risk that the instantaneous adhesiveness and adhesive strength, which are important properties, may also be reduced.

[0004]

In order to solve the above-mentioned problems, the present inventors have synthesized various 2-cyanoacrylates, and identified 2-cyanoacrylates containing a specific novel aromatic group. The present invention has been completed by finding that these problems 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-C 6 H 5 ( where, R represents an alkylene group having 2 to 6 carbon atoms)

The present invention relates to a novel 2-cyanoacrylate represented by the above general formula, and specific compounds include 2-phenylethyl 2-cyanoacrylate and 3-phenylacrylate.
Phenylpropyl 2-cyanoacrylate, 1-methyl-2-
Phenylethyl 2-cyanoacrylate, 2-phenylpropyl 2-cyanoacrylate, 4-phenylbutyl 2-cyanoacrylate, 1,1-dimethyl-2-phenylethyl 2-cyanoacrylate, 1-ethyl-2-phenylethyl 2- Cyanoacrylate, 2-phenylbutyl 2-cyanoacrylate, 3-phenylbutyl 2-cyanoacrylate, 5-phenylpentyl 2-cyanoacrylate, 6-phenylhexyl
2-cyanoacrylate and the like can be mentioned.

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-cyanoacrylates of the present invention are
Like the conventional compounds, it is an unstable compound that is easily polymerized by water present in the air or on the surface of the substance, but can be stably used by adding an appropriate polymerization inhibitor. 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-butylphenol, etc. It can be stably used by adding at least one of radical polymerization inhibitors. The appropriate addition amount of such a polymerization inhibitor varies somewhat depending on the kind of each polymerization inhibitor, but in general, it is preferably in the range of 1 to 10000 ppm, respectively.

Although the novel 2-cyanoacrylate of the present invention can be used alone as a raw material for instant adhesives, it can also be used as a mixture 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 an amount that does not impair the properties of the novel 2-cyanoacrylate of the present invention. % Or less is preferable.

In order to improve heat resistance and durability,
It is also possible to add a cross-linking agent in which both ends of the alkylene glycol are esters of 2-cyanoacrylic acid or 2-cyano-2,4-pentadienoic acid.

In the case where 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 is 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 another vinyl monomer, is converted into a homopolymer or a copolymer and dissolved in a solvent. Can be used as a coating agent or binder.

[0014]

The 2-cyanoacrylate of the present invention, when used as a raw material of an adhesive and applied to an adherend, does not cause a whitening phenomenon due to polymerization after volatilization and does not emit a pungent odor. It also has an excellent effect on adhesiveness and adhesive strength.

[0015]

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

Example 1 Synthesis of 2-phenylethyl 2-cyanoacrylate In a three-necked flask equipped with a stirrer, a thermometer, and a water separator, 510 g of 2-phenylethanol, 355 g of cyanoacetic acid, 417 ml of toluene, and 15 g of p-toluenesulfonic acid. Charge
The reaction was carried out for 7 hours while azeotropically removing the produced water under heating under reflux. After neutralization with 1000 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 628 g (yield 80%) of 2-phenylethylcyanoacetate having a boiling point of 146 to 156 ° C./5 mmHg. In a four-necked flask equipped with a stirrer, a thermometer, a water separator, and a dropping funnel, 33 g of paraformaldehyde and 160 m of toluene.
l, 0.4 ml of piperidine were charged, and after heating to 80 ° C,
At the same temperature, 189 g of 2-phenylethyl cyanoacetate was added from a dropping funnel. The mixture was heated to reflux and reacted for 15 hours while azeotropically removing water produced by the condensation reaction to obtain a viscous yellowish brown liquid. After removing toluene under atmospheric pressure, 3.6 g of polyphosphoric acid, 3 g of hydroquinone and 100 g of tricresyl phosphate were added and mixed sufficiently. Desolvation under reduced pressure followed by 170-2 under reduced pressure of 4 mmHg
Depolymerization was carried out by heating to 05 ° C to obtain 112 g of a distillate having a temperature of 128 to 149 ° C. This fraction was distilled in the presence of a small amount of polyphosphoric acid and hydroquinone to give a boiling point of 117 to 125 ° C / 3.
78 g (yield 39%) of mmHg compound was obtained, and ¹ H-NMR
From the spectrum, it was confirmed to be 2-phenylethyl 2-cyanoacrylate. This compound is a solid at room temperature,
The melting point was 30-31 ° C. 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 to 7.50 ppm (m, 5H, (* d)) 6.97ppm (s, 1H, (* a)) 6.56ppm (s, 1H, (* a)) 4.44ppm (t, J = 9.6Hz, 2H , (* b)) 3.01ppm (t, J = 9.6Hz, 2H, (* c)) CH 2 (* a) = C (CN) -CO 2 - CH ₂ ^{(* b)} -CH ₂ ^{(* c)} -
C ₆ H ₅ ^{(* d)}

Example 2 Synthesis of 3-phenylpropyl 2-cyanoacrylate In a three-necked flask equipped with a stirrer, a thermometer and a water separator, 253 g of 3-phenyl-1-propanol and 158 of cyanoacetic acid were added.
g, 186 ml of toluene and 6.8 g of p-toluenesulfonic acid were charged, and the reaction was carried out for 6 hours while heating and refluxing to remove produced water by azeotropic distillation. NaHCO ₃ 10% aqueous solution 357ml
After neutralizing with, Na ₂ SO ₄ was added to the organic layer and dried. After filtration, the solvent was removed under reduced pressure, followed by distillation to obtain 266 g (yield 70%) of 3-phenylpropyl cyanoacetate having a boiling point of 137 to 144 ° C./3 mmHg. A four-necked flask equipped with a stirrer, a thermometer, a water separator, and a dropping funnel was charged with 18.6 g of paraformaldehyde, 62 ml of toluene and 0.1 ml of piperidine, heated to 80 ° C, and then heated to 3-phenylpropylcyano at the same temperature. Acetate 13
2 g was added from the dropping funnel. The mixture was heated to reflux and the water produced by the condensation reaction was azeotropically removed while reacting for 13 hours to obtain a viscous yellowish brown liquid. After removing toluene under atmospheric pressure, 3.7 g of polyphosphoric acid and 0.9 of hydroquinone
g, tricresyl phosphate 66 g, and mixed well. Following vacuum dewatering, 180 mm under reduced pressure of 3 mmHg
Depolymerization was performed by heating to ~ 215 ° C to obtain 79 g of a fraction at 136-152 ° C. This fraction is distilled in the presence of a small amount of polyphosphoric acid and hydroquinone to give a boiling point of 128 to 134 ° C /
44 g (yield 33%) of 3 mmHg compound was obtained, and ¹ H-NM
From the R spectrum, it was confirmed to be 3-phenylpropyl 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: 6.99 to 7.40 ppm (m, 5H, (* e)) 6.94ppm (s, 1H, (* a)) 6.52ppm (s, 1H, (* a)) 5.24ppm (T, J = 9.0 Hz, 2H, (* b)) 2.72 ppm (t, J = 10.4 Hz, 2H, (* d)) 1.80 to 2.20 ppm (m, 2H, (* c) ^{_{)) CH 2 (* a)}} = C (CN) -CO 2 -CH 2 (* b) -CH 2 (* c) -
^{_{CH 2 (* d) -C 6}} H 5 (* e)

Application Example 1 2-Phenylethyl 2-cyanoacrylate obtained in Example 1 was heated to 35 ° C. to form a liquid, and 40 ppm of sulfur dioxide and 200 ppm of hydroquinone were added. JIS-K-6
According to 861, when the set time of the hard vinyl chloride was measured at 35 ° C. and 60% RH, it was 30 seconds. Also, when the tensile shear bond strength of iron was measured, it was 110
It was kgf / cm ² .

Application Example 2 3-phenylpropyl 2-cyanoacrylate obtained in Example 2 was added with 40 ppm of sulfur dioxide and 200 ppm of hydroquinone.
Was added and the set time of the hard vinyl chloride was measured according to JIS-K-6861. When the tensile shear bond strength of iron was measured,
It was 125 kgf / cm ² .

Application Example 3 75/25 (weight / weight) of 2-phenylethyl 2-cyanoacrylate and ethyl 2-cyanoacrylate obtained in Example 1
By weight) a mixture was made and 40 ppm sulfur dioxide and 200 ppm hydroquinone were added. When the set time of the hard vinyl chloride was measured according to JIS-K-6861, it was 20 seconds. The tensile shear bond strength of iron was measured and found to be 130 kgf / cm ² .

Application Example 4 In order to examine 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 Examples 2 and 3 and the commercially available ethyl 2-cyanoacrylate adhesive were dropped in another petri dish. When left at 23 ° C. and 50% RH for 24 hours, the entire glass surface of the petri dish turned white with the commercially available adhesive, but the adhesives of Application Example 1, Application Example 2 and Application Example 3 showed a complete whitening phenomenon. There wasn't. Further, when the odors of the four adhesives were compared, a strong irritating odor was perceived with the commercially available adhesive, but a slight irritating odor was observed with the adhesive of Application Example 3. The adhesive of No. 2 had almost no odor.

[0022]

EFFECT 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 and adhesive strength can be obtained.
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 2-phenylethyl 2-cyanoacrylate obtained in Example 1. FIG.

2 is an NMR chart of 2-phenylpropyl 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-C 6 H 5 ( where, R represents an alkylene group having 2 to 6 carbon atoms)