Alpha-Cyanocrylate adhesive composition of matter

Abstract: An α -cyanoacrylate adhesive composition of matter consisting essentially of 100 weight parts of α - cyanoacrylate and 0,01∼0,1 weight parts of at least a compound represented by a general formula wherein X represents a hydrogen atom or methyl group and Y an R or RCO (R represents a hydrocarbon residual group not containing any anion polymeric group) and m is an integer of 100≧m≧4. By addition of the above compound to α - cyanoacrylate the adhesive's set time can be shortened and the adhesion strength in the initial stage can be improved even if the surface of the material to be adhered is acidic or tends to dry.

Description: The present invention relates to α-cyanoacrylate adhesive composition of matter for improvement of initial adhesion strength and set time. α-cyanoacrylate being conventionally used as adhesive composition of matter represented by a general formula CH₂ = C(CN)-COOR' (where R' represents alkyl group, alkenyl group, aralkyl group, haloalkyl group, dicyclohexyl group, phenyl group et cetera with a carbon number of not more than 16) has the property to be susceptible to anionic polymerization. It can be polymerized to set within a short time of several seconds to several minutes at normal temperature through the action of various anion active substances such as water adhering to the surface of a solid substance, humidity in the atmosphere and other alkaline substances even in the absence of any catalyst. It has, therefore, hitherto been widely used as a material of instantaneous adhesives for industrial, medical and general household uses. The α-cyanoacrylate adhesive, however, has the defect of its set time getting markedly longer if the surface to be adhered should be acidic or the quantity of water should be too small and, when the materials to be adhered are such as wooden articles, zinc chromate-plated steel plates, polyester, bakelite or EPDM, the set time is unduly long and the adhesion strength is too low. As a prior art for improving the initial adhesion strength of α-cyanoacrylate adhesives has been known a method of using a polyalkyl ether (metha)acrylate-type plasticizer in combination with polyhydroxyphenyl carboxylic acid ester, pyrogallol or the like (Japanese Patent Publication No. 26513/1985, Japanese Patent Publication No. 41668/1989). The European Patent Application EP-A-063 037 discloses an adhesive composition which comprises (A) an α-cyanoacrylate ester, (B) an aliphatic polyol or a derivative thereof or a polyether or a derivative thereof and (C) an aromatic polyol. Even with these improvements, there are still problems concerning the set time and the initial adhesion strength obtainable, these being important problems still to be solved. According to the present invention, an α-cyanoacrylate adhesive composition is provided as defined in the claims. The present inventors have found that the set time and the adhesion strength as well as the storage stability can be improved by adding to the α-cyanoacrylate a compound having an acryloxy group or methacryloxy group which is copolymerizable with α-cyanoacrylate and also an urethane linkage in its structure of molecules without loss of any of the known favorable properties of α-cyanoacrylate. In the present invention the aforementioned reactive compounds to be added to cyanoacrylate are represented by the following general formula (1) or (2): wherein X represents a hydrogen atom or methyl group and Y an R or RCO ( R , in turn, represents a hydrocarbon residual group not containing any anion polymeric group) and m is an integer of 100 ≧ m ≧ 4. As the reactive compound represented by the aforementioned, any reactive compound of those represented by the following chemical formulae may preferably be used: As the reactive compound of general formula (2) above, the substances represented by the following chemical formulae, among others, are preferably used: The amount to be added of such compounds is most preferably within a range of 0.01 ∼ 1.0 weight parts to 100 weight parts of α-cyanoacrylate. If it is more than 1.0 parts, it results in a too high viscosity and too long set time of the adhesive in question, while, if it is less than 0,01 parts, it results in an insufficient acceleration of setting and resultant failure of shortening the set time and improving the adhesion strength. Of the compounds represented by the above general formulae (1) and (2), those with the integer n less than 4 are less effective to shorten the set time, while, if the integer is not less than 100, the solubility for α-cyanoacrylate monomer tends to get worse. EXAMPLES The reactive compound represented by the general formula (2) was prepared by stirring a mixture of 2-methacryloyloxyethyl isocyanate and polyethylene glycol for several hours under heating at 40∼70°C in the presence of an organic tin compound (di-n-butyl tin dilaurate et cetera). The number m in the formula (2) was adjusted through proper selection of the number of repetition m of CH₂-CH₂-O in the material polyethylene glycol. The reactive compounds in the formulae (4) and (6) could be easily synthesized by letting 2-methacryloyloxyethyl isocyanate react with methoxypolyethylene glycol. The adhesive behavior test of the adhesive composition of matter according to the present invention prepared by adding compounds (6) or (8) was carried out as follows. As materials to be adhered were selected steel plate, zinc-chromate-plated steel plate and birch plate, each surface of the materials was coated with the adhesive composition of matter, the same kind of the materials to be adhered to the above materials were pressed onto the coated surface via the adhesive and the set time , tensile shear strength after setting, compressive shear strength and storage stability of the aforementioned composition were tested. These tests were made according to JIS (Japanese Industrial Standard) as below. 1. Set time: JIS K6861 "Test method for α-cyanoacrylate-based adhesives" 2. Tensile shear strength: JIS K6861 "Test method for α-cyanoacrylate-based adhesives" 3. Compressive shear strength: JIS K6852 "Test method for adhesive's compressive shear strength" 4. Storage stability: JIS K6861 "Test method for α-cyanoacrylate-based adhesives" In these tests examined were the influences that the quantity of the admixed reactive compounds have on the adhesion properties. More specifically, Examples 1-10 were prepared by adding 0.01∼1 weight parts of those compounds of the formula (6) or (8) (X=CH₃, m≒23) to 100 weight parts of α-cyanoacrylate. Comparative Examples 1-6 were also prepared by the addition of 0,005 and 5 weight parts either of compounds of formulae (6) and (8) to 100 weight parts of α-cyanoacrylate and by the addition of no compound. The results of adhesive behavior tests are shown in Table 1. As can be seen from Table 1, the set time can be shortened and the strength after setting is practically enough if the quantity of the reactive compound is not less than 0.01 part. Thus, by admixing α-cyanoacrylate with a compound having acryloxy group or methacryloxy group copolymerizable with α-cyanoacrylate also having urethane linkage in its molecule it is possible to markedly improve the setting property in the initial stage of setting. This is supposed to be due to the presence of urethane linkage in the reactive compound but the reaction mechanism has not yet been clarified to date. By the use of α-cyanoacrylate adhesive composition of matter of the present invention it is possible to markedly improve the setting time in the initial stage of setting and also to improve the adhesion strength after setting even if the material to be adhered has its surface acidic or is tending to dry.

Claims: An α-cyanoacrylate adhesive composition of matter consisting essentially of 100 weight parts of α-cyanoacrylate and 0.01 to 1.0 weight parts of at least one reactive compound represented by general formula (1) below: [wherein X represents a hydrogen atom or methyl group and Y represents an R or RCO ( R represents a hydrocarbon residual group not containing any anion polymeric group), and m is an integer of 100 ≥ m ≥ 4]. An α-cyanoacrylate adhesive composition of matter according to claim 1, wherein X in said general formula (1) represents a methyl group and m is 4 or 23. An α-cyanoacrylate adhesive composition of matter according to claim 1, wherein the reactive compound represented by said general formula (1) is replaced by a reactive compound represented by general formula (2): [wherein X represents a hydrogen atom or methyl group, and m is an integer of 100 ≥ m ≥ 4]. An α-cyanoacrylate adhesive composition of matter according to claim 3, wherein X in said general formula (2) is a methyl group and m is 4 or 23. An α-cyanoacrylate adhesive composition of matter according to claim 4, wherein m is 23.

Inventors: HIRAI KENICHIRO, NISHIOKA YOSHINOBU, SUGIMAE TOSHIO, TSUGIYAMA TATEKI, HIRAI, KENICHIRO, NISHIOKA, YOSHINOBU, SUGIMAE, TOSHIO, TSUGIYAMA, TATEKI, Hirai, Kenichiro, c/o Koatsu Gas Kogyo Co.,Ltd, Nishioka, Yoshinobu, c/o Koatsu Gas Kogyo Co.,Ltd, Sugimae, Toshio, c/o Koatsu Gas Kogyo Co.,Ltd, Tsugiyama, Tateki, c/o Koatsu Gas Kogyo Co.,Ltd
Applicants: KOATSU GAS KOGYO, KOATSU GAS KOGYO CO., LTD.
Application year: 1992
Main classification: C09J4
IPC codes: C09J4