JPS6229471B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a primer used for pretreatment to accelerate the curing speed of α-cyanoacrylate (hereinafter abbreviated as "ACA") adhesives. Since ACA adhesives were developed in the United States in 1959, they have come to be used as strong one-component instant adhesives not only in many industrial and medical fields, but also in general households in recent years. The most important feature of this adhesive is its instant adhesive property, but like general adhesives, its adhesive property is controlled by the surface condition of the surface to be adhered. In particular, since the present adhesive is of an anionic polymerization type, the curing speed is significantly delayed on acidic surfaces, such as wood surfaces, and surfaces containing various curing inhibitors, such as rubber and engineering plastic surfaces. This delay in curing speed not only diminishes the rapid curing characteristic of this adhesive and its special advantage of shortening bonding time, but also causes whitening in areas around the bonded area. Because of this, it has been strongly desired to improve the appearance of the metal. Until now, many proposals have been made to solve the above problems, in particular, using various basic substances such as alkanolamines, epoxy compounds, dimethylaniline, N-containing heterocyclic compounds, etc.
Diyutylamine, organic titanium compound, quaternary ammonium compound, phosphionium salt, N, N-
A typical method is to pre-treat the surface to be adhered using di-lower alkyl-P(or m)-toluidine or the like. According to the findings of the present inventors, among the above-mentioned methods, the last one that seems to be most effective for accelerating curing (accelerating monomer polymerization) and preventing whitening is N,N-di-lower alkyl-P (or m). - This is a method in which toluidine is dissolved in a solvent in advance and applied to the surface to be adhered, but unfortunately the effect of this pretreatment is not long-lasting and loses its effectiveness quickly after application. However, in actual bonding work, the time required for applying the ACA adhesive after pretreatment is usually indefinite, unless it is done in assembly line work, and users have been requesting that the durability of the primer be increased. is large. In response to such a demand, an important objective of the present invention is to provide durability to the pretreatment effect of N,N-dilower alkyl-P (or m)-toluidine. The present inventor conducted research on a number of additives to enhance the sustainability of N,N-di-lower alkyl-P(or m)-toluidine, and found that saccharin (O-
It has been found that the combined use of benzoic acid sulfimide) and ascorbic acid or isoascorbic acid has a remarkable effect. The present invention is based on this new knowledge, and uses N,N-di-lower alkyl-P (or m)-toluidine, saccharin, ascorbic acid or isoascorbic acid (erythrobic acid) as a pretreatment agent for ACA adhesives. The gist of this is to use them together. In the present invention, N used as a pretreatment agent,
N-di-lower alkyl para-toluidine is N,
Compounds in which two hydrogen atoms attached to the nitrogen atom are substituted with lower alkyl groups, such as N-dimethyl para-toluidine and N,N-diethyl para-toluidine, are also referred to as di-lower alkyl meta-toluidine. , N-dimethyl metatoluidine,
N,N such as N,N-diethyl metatoluidine
-lower alkyl-substituted metatoluidines. These N-substituted toluidines are methanol,
Lower alcohols such as ethanol, acetone,
It is used by dissolving it in an organic solvent such as ether or n-hexane, and its concentration is preferably 2 to 30% by weight. Several of the above N-substituted toluidines may be used as a mixture, or a small amount of amines such as dimethylaniline or alkanolamine may be mixed in addition to the N-substituted toluidines. Next, the amount of saccharin used in combination with the above N-substituted toluidine is 0.5 to 20% by weight based on the compound, and the amount of ascorbic acid or isoascorbic acid is 0.03 to 20% by weight based on the compound. % is preferred. These saccharin and ascorbic acid or isoascorbic acid are
- It may be added to a solution of substituted toluidines, or
Further, they may be used in combination by separately preparing an organic solvent solution and mixing at the time of use, or by separately spraying or the like. According to the present invention, the effect is still observed even 24 hours after the pretreatment, whereas in the case of pretreatment with only N-substituted toluidines, the pretreatment effect already decreases after 30 minutes. The effect almost disappears after a few hours. The natural whitening prevention effect also lasts for a long time in the case of the present invention. Note that amines such as N-substituted toluidine generally emit a strong amine odor, deteriorating the working environment, but if saccharin and ascorbic acid or isoascorbic acid are used together according to the present invention, the amines such as N-substituted toluidine emit a strong amine odor, although the cause is unknown. Since the generation of odor is suppressed, it is effective in terms of occupational hygiene and pollution prevention. This effect is also a noteworthy effect of the invention. The details of the present invention will be explained below with reference to Examples.
However, each example is for illustrative purposes and is not intended to limit the technical scope of the invention. (1) Examples 1 and 2, Comparative Examples 1 and 2 After applying the pretreatment solution shown in Table 1 to the surface of a polished mild steel plate (JISG3141) that had been degreased with acetone,
One drop (approximately 20 mg) of ACA was dropped onto the surface of the steel plate from a nozzle over time, and the curing time was measured. The end of curing is such that it no longer sticks to your fingertips. The results are shown in Table 1 below. The composition of the pretreatment agent for each example and comparative example is as follows (% is weight): - Reference example No pretreatment Example 1 N,N-dimethylparatoluidine (DMPT) 5%, methanol 93.5%, saccharin 1%, ascorbic acid 0.5%, Comparative example 1 Company A primer Comparative example 1' DMPT 5%, methanol 95% Example 2 DMPT 20%, methanol 78.5%, saccharin 1%, ascorbic acid 0.5% Comparative example 2 DMPT 20%, methanol 80 %

【table】

[Table] As is clear from the results in the above table, when comparing the examples of the present invention and the comparative examples, it can be seen that the curing time becomes significantly different as the standing time elapses. In addition, the prevention of whitening phenomenon lasted for a long time as well as the curing time. (2) Examples 3 to 6, Comparative Examples 3 to 6 Planed cherry wood with a moisture content of 8.7% was used as the base material, and after applying the following pretreatment agent on both sides, α-cyanoethyl acrylate was applied over time. was applied to the surface to be bonded, the base materials were bonded together (bonded area of 1 square inch), and the set time was measured (Measurement method:
According to JISK6861-1977 set time measurement method. ). The results are shown in Table 2 below. Pretreatment agent Reference example No pretreatment Example 3 DMPT 3%, methanol 95%, saccharin 1%, ascorbic acid 1% Comparative example 3 Company A primer Comparative example 3' DMPT 3%, methanol 97% Example 4 DMPT 5%, methanol 93% %, saccharin 1%, ascorbic acid 1% Comparative example 4 DMPT 5%, methanol 95% Example 5 DMPT 8%, methanol 90%, saccharin 1%, ascorbic acid 1% Comparative example 5 DMPT 8%, methanol 92% Example 6 DMPT20 %, methanol 77.5%, saccharin 2%, ascorbic acid 0.5%

[Table] As is clear from the table above, a noticeable difference appears after one hour between the example and the comparative example, and in the case of the present invention, the setting time was as short as 10 to 15 seconds even after being left for 72 hours. I understand that. Incidentally, as can be seen from each example, when the concentration of DMPT is 5% or more, there is no noticeable correlation between the durability of the primer effect and the concentration of DMPT. (3) Examples 7 to 10, Comparative Examples 7 to 10 After polishing an aluminum (JISH4000) test piece with abrasive paper AA#240 and degreasing with acetone,
Apply the following pretreatment agent on both sides, then apply over time.
ACA was applied, the test pieces were crimped together, and the set time was measured (Measurement method: JISK6761-
Based on the 1977 Set Time Measurement Method. ). The results are shown in Table 3 below. Pretreatment agent Reference example No pretreatment Example 7 DMPT 3%, methanol 95%, saccharin 1%, ascorbic acid 1% Comparative example 7 Company A primer Comparative example 7' DMPT 3%, methanol 97% Example 8 DMPT 5%, methanol 93% %, saccharin 1%, ascorbic acid 1% Comparative example 8 DMPT 5%, methanol 95% Example 9 DMPT 8%, methanol 90%, saccharin 1%, ascorbic acid 1% Comparative example 9 DMPT 8%, methanol 92% Example 10 DMPT20 %, methanol 77.5%, saccharin 2%, ascorbic acid 0.5% Comparative example 10 DMPT 20%, methanol 80%

[Prescription example]

500 g of N,N-dimethylamino metatoluidine (DMMT), 100 g of saccharin, and 50 g of ascorbic acid are brought to a total volume of 10 with anhydrous methanol, and the mixture is poured into a pound bottle and sealed to produce a primer. As described above, the present invention has great practical value because it can significantly enhance the lasting effect of the primer when adhering with an ACA adhesive.

Claims (1)

[Scope of Claims] 1. α-cyano characterized by containing N,N-di-lower alkyl para-toluidine and/or N,N-di-lower alkyl meta-toluidine, saccharin, and ascorbic acid and/or isoascorbic acid. Acrylate adhesive-like primer. 2 α according to claim 1, comprising an organic solvent solution of N,N-di-lower alkyl para-toluidine and/or N,N-di-lower alkyl meta-toluidine, saccharin, and ascorbic acid and/or isoascorbic acid. -Cyanoacrylate adhesive-like primer.