(19) ⌃&↵↵ ⇣✏ ✏⌫ ⌃ (11) EP 2 154 214 A2 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: (51) Int Cl.:⇤ 17.02.2010 Bulletin 2010/07 C09J 4/00 (2006.01) (21) Application number: 09167423.4 (22) Date of filing: 07.08.2009 (84) Designated Contracting States: • Elgrabli, Sophie AT BE BG CH CY CZ DE DK EE ES FI FR GB GR 95310, Saint Ouen L’Aumone (FR)⇤ HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL •Motoki, Shigekazu PT RO SE SI SK SM TR Hachioji-⇤shi Tokyo 193-0941 (JP)⇤ (30) Priority: 07.08.2008 JP 2008204737 (74) Representative: Grünecker, Kinkeldey, Stockmair & Schwanhäusser (71) Applicant: Threebond Co., Ltd.⇤ Anwaltssozietät Hachioji-⇤shi, Tokyo 193-0941 (JP)⇤ Leopoldstrasse 4 80802 München (DE)⇤ (72) Inventors: •Kojima, Kazuhiro 95310, Saint Ouen L’Aumone (FR)⇤ (54) Cyanoacrylate-⇤based adhesive composition (57) The present invention relates to a cyanoacr- a high decreasing rate from initial value, namely an ex- ylate-⇤based adhesive composition containing (A) an α- cellent retention rate of wet heat resistance, in a wide cyanoacrylate, (B) a (meth)⇤acryloyl group-⇤containing range of applications such as adhesion of synthetic rub- multifunctional compound and (C) cumene hydroperox- bers or elastomers such as SEBS, EPDM and chloro- ide in which a content of cumene (1-⇤methyl-⇤1-⇤ethylben- prene rubber, and adhesion of heterogeneous materials zene) is less than 5 wt%. According to the invention, there of iron/⇤synthetic rubbers or elastomers, to say nothing of can be provided an α-⇤cyanoacrylate-⇤based adhesive adhesion of iron/⇤iron. composition having excellent wet heat resistance, also having excellent chemical resistance and further having EP 2 154 214 A2 Printed by Jouve, 75001 PARIS (FR) EP 2 154 214 A2 Description [Technical Field] 5 ⇤[0001] The present invention relates to an α-⇤cyanoacrylate-⇤based adhesive used for instant adhesion for a wide range of applications such as metals, rubbers and plastics, and particularly to a cyanoacrylate-⇤based adhesive composition excellent in wet heat resistance under conditions of high temperature and humidity and in chemical resistance. [Background Art] 10 ⇤[0002] An α-⇤cyanoacrylate-⇤based adhesive is rapidly anionically polymerized and cured with a slight amount of moisture adsorbed on surfaces of adherends to allow the adherends to be extremely strongly adhered to each other in a short period of time, so that it has been widely utilized for adhesion of metals, plastics, rubbers and the like, as a instant adhesive of a one-⇤component roomtemperature curing type. 15 ⇤[0003] The α-⇤cyanoacrylate-⇤based adhesive is generally poor in moisture resistance and water resistance, and has had the drawback of being difficult to use particularly for water-⇤related applications. The reasons for that include a significant influence on an adhesive interface under high wet heat, because a cured material itself of the α-⇤cyanoacrylate- based adhesive decomposes with water, an alkaline solvent or the like, or cure strain is liable to occur at the time of adhesion due to poor flexibility of the cured material, which causes a poor relaxing action to external stress or internal 20 stress. However, it is hard to throw away the merits of rapid curing capability with moisture at room temperature with one component constitution, so that an α-⇤cyanoacrylate-⇤based adhesive having good productivity and showing excellent moisture resistance and water resistance has been desired. ⇤[0004] As techniques for relaxing internal stress which occurs at the time of adhesion, or external stress applied from the outside after adhesion, there have been reported one in which a saturated copolyester is incorporated for the purpose 25 of imparting flexibility (JP-⇤A-⇤63-284279), one in which an acrylonitrile-⇤butadiene copolymer is incorporated (JP-⇤A- 7-53924) and the like. However, in these systems, the flexibility imparting agent is present only in a dispersed state in a cyanoacrylate cured material, and does not prevent deterioration of the cyanoacrylate cured material itself. It is therefore hard to say that satisfactory wet heat resistance is possessed under circumstances of high temperature and humidity. ⇤[0005] Further, aside from these, there have been reported techniques of improving wet heat resistance of a cured 30 material itself by incorporating a specific acrylic monomer into an α-⇤cyanoacrylate-⇤based adhesive. First, JP-⇤A-⇤58-185666 has reported an α-⇤cyanoacrylate-⇤based adhesive to which a C1-⇤C4 alkyl or alkoxy (meth)⇤acrylate has been added. However, even this has not showed sufficient wet heat resistance. Thereafter, it has been reported to add a trifunctional or more functional acrylate containing a pentaerythritol residue in JP-⇤A-⇤6-145605 and JP-⇤A-⇤145606. In these inventions, wet heat resistance adhesion to EPDM and chloroprene rubber has been reported. However, all are the results of an 35 accelerated test for a relatively short time of 72 hours at 70°C and 95%, and it is somewhat open to question whether sufficient wet heat resistance is possessed under high wet heat and for water-⇤related applications or not. Furthermore, the trifunctional or more functional acrylate carried out in these inventions is only a trifunctional or hexafunctional acrylate. ⇤[0006] Additionally, WO 2006/098438 discloses an α-⇤cyanoacrylate-⇤based adhesive which shows an excellent wet heat resistance by adding specific (meth)⇤acrylate to α-⇤cyanoacrylate. However, in view of a decreasing rate from initial 40 value, namely a retention rate of wet heat resistance, the wet heat resistance thereof was not necessarily sufficient. ⇤[0007] [Patent Document 1] JP-⇤A-⇤63-284279 [Patent Document 2] JP-⇤A-⇤7-53924 45 [Patent Document 3] JP-⇤A-⇤58-185666 [Patent Document 4] JP-⇤A-⇤6-145605 [Patent Document 5] JP-⇤A-⇤6-145606 [Patent Document 6] WO 2006/098438 50 [Disclosure of the Invention] [Problems That the Invention Is to Solve] ⇤[0008] An object of the invention is to provide an α-⇤cyanoacrylate-⇤based adhesive composition having excellent wet 55 heat resistance, also having excellent chemical resistance and further having a high decreasing rate from initial value, namely an excellent retention rate of wet heat resistance, in a wide range of applications such as adhesion of synthetic rubbers or elastomers such as SEBS, EPDM and chloroprene rubber, and adhesion of heterogeneous materials of iron/ synthetic rubbers or elastomers, to say nothing of adhesion of iron/⇤iron. 2 EP 2 154 214 A2 [Means for Solving the Problems] ⇤[0009] In order to solve the above-⇤mentioned problems, intensive studies have been made. As a result, it has been found that an α-⇤cyanoacrylate-⇤based adhesive composition in which a specific (meth)⇤acrylate and a peroxide are con- 5 tained in an α-⇤cyanoacrylate shows excellent wet heat resistance, thus completing the invention. Incidentally, wet heat resistance of the invention means good deterioration resistance under conditions of high temperature and high humidity. ⇤[0010] That is, in the invention, the above-⇤mentioned problems have been solved by a cyanoacrylate-⇤based adhesive composition containing (A) an α-⇤cyanoacrylate, (B) a multifunctional (meth)⇤acrylate and (C) cumene hydroperoxide in which the content of cumene (1-⇤methyl-⇤1-⇤ethylbenzene) is less than 5 wt%, as essential components. 10 ⇤[0011] As a preferred embodiment, the invention provides a composition in which the above-⇤mentioned component (B) is (B1) trimethylolpropane tri⇤(meth)⇤acrylate, that is, a cyanoacrylate-⇤based adhesive composition containing (A) an α-⇤cyanoacrylate, (B1) trimethylolpropane tri⇤(meth)⇤acrylate, and 15 (C) cumene hydroperoxide in which the content of cumene (1-⇤methyl-⇤1-⇤ethylbenzene) is less than 5 wt%.⇤ The composition of this embodiment is preferred because it shows extremely excellent wet heat resistance. [Advantages of the Invention] 20 ⇤[0012] The cyanoacrylate-⇤based adhesive composition according to the invention shows excellent wet heat resistance and has appropriate flexibility, and further, has sufficient resistance also to an acidic atmosphere, a basic atmosphere, boiling water, gasoline and the like. This widens the application range to water-⇤related applications, applications under circumstances of high humidity or the use under special circumstances which has been difficult to be realized by con- ventional instant adhesives, thereby industrially making a substantial contribution to process reduction, cost cutting and 25 the like. [Best Mode for Carrying Out the Invention] ⇤[0013] The invention is described in detail below. As the kind of α-⇤cyanoacrylate (component (A)), an α-⇤cyanoacrylate 30 which has hitherto been known is usable. Specific examples thereof include alkyl and cycloalkyl α-⇤cyanoacrylates such as methyl α-⇤cyanoacrylate, ethyl α-⇤cyanoacrylate, propyl α-⇤cyanoacrylate, butyl α-⇤cyanoacrylate and cyclohexyl α- cyanoacrylate, alkenyl and cycloalkenyl α-⇤cyanoacrylates such as allyl α-⇤cyanoacrylate, methallyl α-⇤cyanoacrylate and cyclohexenyl α-⇤cyanoacrylate, alkynyl α-⇤cyanoacrylates such as propangyl α-⇤cyanoacrylates, aryl α-⇤cyanoacrylates such as phenyl α-⇤cyanoacrylate and toluyl α-⇤cyanoacrylate, hetero atom-⇤containing methoxyethyl α-⇤cyanoacrylate, 35 ethoxyethyl α-⇤cyanoacrylate and furfuryl α-⇤cyanoacrylate, silicon-⇤containing trimethylsilylmethyl α-⇤cyanoacrylate, tri- methylsilylethyl α-⇤cyanoacrylate, trimethylsilylpropyl α-⇤cyanoacrylate and dimethylvinylsilylmethyl α-⇤cyanoacrylate. Of these, ethyl α-⇤cyanoacrylate is most preferred for