JPH0220672B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a 2-cyanoacrylic acid ester adhesive, and particularly to a 2-cyanoacrylic acid ester adhesive (hereinafter referred to as cyano adhesive) that has improved dissolution and removability of the cured adhesive. Cyano adhesives are used in various fields to bond various materials such as metals, ceramics, plastics, rubber, and wood because they polymerize and harden in a short time at room temperature due to moisture and alkali adsorbed on the surface of the adherend, resulting in strong adhesion. It is used for. This adhesive has 2-cyanoacrylic acid ester as its main polymerization component, and is prepared by adding stabilizers, plasticizers, thickeners, and other modifiers as necessary. Through these modification methods, the original purpose of the adhesive,
In other words, efforts have been made to improve various properties such as quick curing, high adhesion, heat resistance, water resistance, impact resistance, peeling resistance, and heat resistance, and to develop compositions that bond faster and more firmly. ing. In recent years, cyano-based adhesives have been used for temporary fixing, especially for temporary fixing, where parts are glued together and then subjected to a specified process, after which the parts are peeled off and collected to be used for their original purpose. Adhesive usage is rapidly increasing. When conventional cyano-based adhesives are used for this purpose, the adhesion speed and adhesion are sufficient, but it is difficult to peel and recover the processed parts, which is the main purpose of this method, and requires long peeling work under harsh conditions. This not only resulted in poor work efficiency, but also often resulted in deterioration and damage to processed parts, which was a practical problem. Therefore, the present inventors have developed a cyano-based adhesive that has excellent releasability and is suitable for temporary adhesion for processing work of parts. As a result of investigating a new cyano-based adhesive composition that can be peeled off and recovered in a short period of time under milder processing conditions without worrying about deterioration or damage to the parts, we found that The inventors have found that a composition in which a polymer is added to 2-cyanoacrylic acid ester to modify it is preferable, leading to the present invention. Therefore, the present invention provides X-CH ₂ -Y (in the formula
is a polymer obtained by addition condensation of an active methylene compound represented by COOR (R is an alkyl group or an alkoxyalkyl group, groups selected from CN, NO ₂ , which are the same or different from each other) and formaldehyde, and 2- An adhesive composition containing a cyanoacrylic acid ester is provided. To explain the present invention in detail, the 2-cyanoacrylic acid ester used in the present invention includes all common esters. Specific examples include methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, allyl, propargyl, benzyl, phenyl, methyl cellosolve, ethyl cellosolve, 2-
Examples include esters such as chloroethyl, fluoroethyl, and fluoropropyl. In the present invention, an adhesive composition is formed by adding a polymer obtained by addition condensation of an active methylene compound and formaldehyde or paraformaldehyde to the above-mentioned 2-cyanoacrylic acid ester. X, Y
represents the same or different groups selected from COOR, CN, NO ₂ , and when the above R represents an alkyl group or an alkoxyalkyl group having 10 or less carbon atoms, the formula X-CH ₂ -Y The compounds shown are used. Such active methylene compounds include malonic acid diesters such as dimethyl malonate, diethyl malonate, dipropyl malonate, and dibutyl malonate, particularly those with C=1 to 2-cyanoacrylate in terms of solubility and stability. Malonic acid diesters having 6 alkyl groups are preferred;
In addition, cyanoacetates such as malondinitrile, methyl cyanoacetate, ethyl cyanoacetate, propyl cyanoacetate, butyl cyanoacetate, octyl cyanoacetate, octadecyl cyanoacetate, ethoxyethyl cyanoacetate, butoxyethyl cyanoacetate, methyl nitroacetate, nitroacetate, etc. Examples include nitroacetic esters such as ethyl acetate and butyl nitroacetate. In addition-condensing such an active methylene compound with formaldehyde or paraformaldehyde, both of these compounds are dissolved in a solvent and reacted by heating in the presence of a catalyst. That is, an active methylene compound and formaldehyde or paraformaldehyde are used alone or in combination of two or more in water, alcohol, hydrocarbon, ether, etc. as a solvent,
As a catalyst, acidic substances such as sulfuric acid, paratoluenesulfonic acid, phosphoric acid, strongly acidic ion exchange resins, etc., and basic substances such as caustic soda, caustic potash, soda carbonate, potassium carbonate, calcium hydroxide, etc.
Addition condensation is carried out using pyridine, piperidine, triethylamine, triethylamine hydroxide, tributylamine hydroxide, basic ion exchange resin, etc. The addition condensation polymer obtained in this way may be used as it is, but if the solubility in 2-cyanoacrylic acid ester or the stability of the dissolved composition is lacking, the addition polymer may be dehydrated, dried, It can also be used after performing purification treatment such as removal of adhering catalyst residues, etc., as necessary. When obtaining the adhesive composition of the present invention, if the addition polymer obtained by addition condensation of the above-mentioned active methylene compound and formaldehyde is used, 10 parts or less of the 2-cyanoacrylic acid ester is cured. The solubility of the adhesive used was insufficient, and 180%
If the amount is more than 10 parts, the quick curing property and adhesive strength will be too low, so 10 to 180 parts, particularly preferably 50 to 150 parts, are dissolved. In order to improve the stability and other physical properties of this melt,
Acidic substances such as SO ₂ , paratoluenesulfonic acid, dodecylbenzenesulfonic acid, adipic acid ester, phthalic acid ester, sebacic acid ester, phosphoric acid ester, citric acid ester, tartaric acid ester, polyalkylene glycol diether, polyalkylene glycol diester It can also be modified by adding polyalkylene glycol ether ester, etc. If desired, methyl methacrylate polymer, butyl acrylate polymer, 2-
Soluble polymers such as cyanoacrylate polymers, polyvinyl ether, polyvinyl butyral, polyvinyl acetate, cellulose ethyl, etc. can also be used as fluidity modifiers (thickeners). If too much of these thickeners is added, the solubility and releasability of the cured adhesive may decrease, so it is desirable to use them within the range necessary to adjust fluidity. When increasing the solubility of adhesives cured with conventional compositions obtained by adding plasticizers, ordinary polymers, solvents, surfactants, etc. to 2-cyanoacrylate esters, the adhesive strength becomes extremely slow. This is not preferable because it has drawbacks such as a markedly reduced adhesive strength and cannot withstand processing operations. However, the composition obtained by adding a specific polymer, that is, an addition condensation polymer of an active methylene compound and formaldehyde to the 2-cyanoacrylic acid ester obtained by the present invention, has a high adhesion speed and normal adhesive strength. is roughly the same as conventional cyano adhesives and has excellent bonding work and workability of parts, but after processing, it can be used with organic solvents such as acetone, methyl ethyl ketone, acetonitrile, nitromethane, dimethyl formaldehyde, methylene chloride,
Trichlene, ethyl acetate, butyl acetate, toluene, perfluoroethane, chlorofluorobutane, cyclohexane, tetrahydrofuran, etc. and water can be used singly or in combination, and if necessary, an alkali or surfactant can be added at room temperature or under heating. The parts can be treated and peeled off, or they can be heated in an inert gas atmosphere and peeled off, and the parts can be recovered and worked on. Thus, the adhesive composition of the present invention is an adhesive composition characterized by adding a specific polymer, particularly an addition condensation polymer of an active methylene compound and formaldehyde to 2-cyanoacrylic acid ester, and is an adhesive composition characterized by adding a specific polymer, particularly an addition condensation polymer of an active methylene compound and formaldehyde, to a 2-cyanoacrylic acid ester. It has the same adhesion speed and normal strength as other adhesives, and after processing parts, it can be peeled off and recovered without causing deterioration or damage to the processed parts by subjecting them to room temperature or heat treatment in water, organic solvents, air, or inert gas. This is a new adhesive that can be used for the intended purpose of the component. The composition of the present invention is useful as a temporary adhesive for processing mechanical parts, electronic parts, ceramics, lenses, glass, etc., and can be widely used in the fields of electronic parts, precision machinery, optical equipment, audio equipment, etc. useful. Examples of the present invention are shown below together with synthesis examples.
All parts here indicate parts by weight. Synthesis Example 1 158 parts of diethyl malonate are dissolved in 300 parts of methanol, and 33 parts of paraformaldehyde are added thereto and mixed uniformly. Add 5 parts of piperidine to this mixture and heat to 50°C while stirring. An exothermic reaction occurs and methanol reflux occurs. The reaction was further carried out for 1 hour under refluxing methanol to obtain a pale yellow viscous solution. Methanol is distilled off from this viscous solution at normal pressure, and toluene is
Add 300 parts, heat, and distill off at normal pressure. The obtained residue is treated under reduced pressure of 50 to 10 mmHg to remove the remaining solvent and the like to obtain a pale yellow transparent polymer. Dissolve this in 400 parts of toluene and add 10 parts of
Add 200 parts of ion-exchanged water containing H ₂ SO ₄ and shake thoroughly at room temperature. Leave to stand still to separate the aqueous phase, wash three times with the same amount of ion-exchanged water, and confirm that there is no SO ₄ ^-- . The toluene layer was collected and dehydrated with anhydrous magnesium sulfate, and the toluene was distilled off under normal pressure and reduced pressure to obtain 80 parts of a pale yellow candy-like polymer. Infrared analysis revealed that it was a diethyl malonate-formaldehyde addition condensation polymer. Synthesis Example 2 Instead of washing with sulfuric acid water in Synthesis Example 1, the polymer was treated by passing through a column filled with a sulfonic acid type ion exchange resin, and toluene was distilled off to obtain 75 parts of a similar polymer. Synthesis Example 3 In Synthesis Example 1, 114 parts of ethyl cyanoacetate was used instead of diethyl malonate, and the same reaction was carried out to obtain 65 parts of a pale yellow solid. Infrared analysis revealed that this solid was an addition condensation polymer of ethyl cyanoacetate and formaldehyde. Synthesis Example 4 In the Synthesis Example, instead of washing with sulfuric acid water, Synthesis Example-
The same ion exchange resin treatment as in 2 was carried out to obtain 58 parts of a pale yellow solid, and the same polymer as in Synthesis Example 3 was obtained. Example 1 40 parts of the polymer obtained in (Synthesis Example-1) and 5 parts of triethyl citrate were added to 55 parts of ethyl cyanoacrylate containing SO ₂ as a stabilizer and 0.06% (wt) hydroquinone. It was uniformly dissolved to obtain a pale yellow transparent adhesive composition. The adhesive performance of this composition was measured according to JISK6828, and the set time was 15 to 30 seconds, and the tensile shear strength was 230 kg/cm ² (material: mild steel), showing performance comparable to that of ordinary cyano adhesives. . Furthermore, using this adhesive, a 20 x 20 x 1 mm alumina ceramic plate and a 10 x 20 mm steel plate were bonded together, cured at room temperature for 2 hours, and then peeled under various conditions. For comparison, a conventional product manufactured by Matsumoto Pharmaceutical Industries Co., Ltd. under the trade name "Visca 18M" was used.
An ethyl cyanoacrylate adhesive was used. The results are as shown below, and it was found that peeling was significantly easier than with conventional products, and the material could be recovered without damage or deterioration of quality.

[Table] (Examples 2 to 4) Adhesive compositions were prepared in the same manner using the polymers of Synthesis Examples 2 to 4 in place of the polymer of (Synthesis Example 1) in (Example 1). Obtained. The adhesive properties of these compositions were measured in the same manner as in Example 1, and the results were as follows, and there was no significant difference from ordinary products.

[Table] Furthermore, the releasability was measured in the same manner as in Example 1. The results are shown in Table 3, and the releasability was good without causing any deterioration or damage to the member.

【table】

Claims (1)

[Claims] _1. An _active methylene compound represented by An adhesive composition comprising a polymer obtained by addition condensation of formaldehyde and 2-cyanoacrylic acid ester.