Alpha-Cyanoacrylate-Type Adhesive Composition

United States Patent [191 Motegi et al. [54] a-CYANOACRYLATE-TYPE ADHESIVE COMPOSITION [75] Inventors: Akira Motegi; Eiji Isowa; Kaoru Kimura, all of Nagoya, Japan [73] Assignee: Toagosei Chemical Industry Co., Ltd., Tokyo, Japan [21] Appl. No.: 897,882 [22] Filed: Apr. 19, 1978 [30] Foreign Application Priority Data Apr. 19, 1977 [JP] Japan ................................ .. 52-44129 [51] Int. c1.2 ..................... .. C08F 4/00; C08F 113/14; co31= 118/16 [52] U.S. CI. .................................... .. 526/245; 424/61; 424/77; 428/463; 423/492; 423/514; 423/520; 423/522; 526/193; 526/196; 526/198; 526/204; 526/205; 526/285; 526/292; 526/298 [11] 4,171,416 [45] Oct. 16, 1979 [58] Field of Search ............. .. 526/204, 298, 193, 196, 526/198, 205, 245, 285, 292; 424/61, 77; 260/881 [56] References Cited U.S. PATENT DOCUMENTS 3,527,841 9/1970 Wicker et al. ..................... .. 526/298 3,701,758 10/1972 Maska ................................ .. 526/298 3,759,264 9/1973 Coover et al. ..................... .. 526/298 3,890,278 6/1975 Lehn et al. ......................... .. 526/204 Primary Examiner—Harry Wong, Jr. Attorney, Agent, or Firm—Sughrue, Rothwell, Mion, Zinn and Macpeak [5 7] ABSTRACI‘ A fast-setting a-cyanoacrylate-type adhesive composi- tion having good storage stability comprising an a- cyanoacrylate and about 0.1 ppm or more of at least one macrocyclic polyether compound or an analogue thereof, such as 18-crown-6 or 15-crown-5. 11 Claims, No Drawings 4,171,416 1 oL-CYANOACRYLATE-TYPE ADHESIVE COMPOSITION BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an a.-cyanoacrylate-type adhesive composition, and more particularly to an ad- hesive composition having a fast setting time. 2. Description of the Prior Art a-Cyanoacrylate-type adhesives, because of the in- herent anion-polymerizability of the a-cyanoacrylate monomer as a main component, begin to polymerize in the presence of a weak anion such as in the presence of slight moisture adhering to the surface of the adherend, and can firmly bond almost all materials except certain inert materials such as polyethylene and tetrafluoroeth- ylene resins (e.g., Teflon) within several seconds to several minutes. Hence, they have found extensive use as instantaneous adhesives in industry, in medical uses, in hobby applications, and in the home. The curing of cc-cyanoacrylate-type adhesives is due to the anionic polymerization of the a-cyanoacrylate monomer. When such an adhesive is used to bond mate- rials whose bonding surfaces are acidic, such as wood or surfaces which tend to permit the formation of an acidic oxide coating, the anionic polymerization of the a-cyanoacrylate is inhibited, and the setting time of the adhesive is slow. Thus, the adhesion strength is some- times not entirely satisfactory. For example, wooden materials in general use have a moisture content of about 10% by weight under normal conditions (i.e., at 23° C. and a relative humidity of 55%). In spite of this high water content in the woody tissue and on the sur- face of the wooden materials, a setting time of from several minutes to between ten and twenty minutes is required to bond these wooden materials with conven- tional a-cyanoacrylate-type adhesives. Since a-cyanoa- crylate-type adhesives penetrate into the woody tissue during this period, it is generally considered difficult to bond wooden materials with these adhesives. Usually, wooden materials are acidic because of the presence of sap, etc. in the wood. If the surface of the material is acidic, naturally the anionic polymerization of the a- cyanoacrylate monomer would be hindered, and the speed of curing decreased. Consequently, the effect of the adhesives as instantaneous adhesives decreases dras- tically. A chromate-treated surface of a metal is usually acidic, and a surface obtained by neutralizing the acidic surface using a Unichrome treatment has lower weath- erability than the chromate-treated surface. Accord- ingly, where parts with weatherability are required, such preferably have an acidic chromate-treated sur- face. In bonding such a surface, a-cyanoacrylate-type adhesives have a slow setting time, and the adhesion strength -of the bond is low. a-Cyanoacrylate-type adhesives are chemically reac- tive adhesives which cure by anionic polymerization. These adhesives usually have a low viscosity, and there- fore, when they are applied to the adherend, an initial tackiness, as in the case of rubber-type adhesives, is not obtained with a-cyanoacrylate-type adhesives. The adherend must be fixed for several minutes until anionic polymerization begins. Furthermore, in a bonding operation on an assembly line, the adherend must be fixed for a certain period of time by a jig, etc., and therefore, the efficiency of opera- 5 10 15 20 25 30 35 40 45 50 55 65 2 tion decreases. Since a-cyanoacrylate adhesives are “instantaneous” adhesives, it is necessary for them to cure on many materials with as fast a setting time as possible. The rapidity of the setting time will broaden the range of application of a-cyanoacrylate-type adhe- sives. Many methods for increasing the setting time of a- cyanoacrylate-type adhesives have been investigated heretofore. These methods include, for example, a method which involves increasing the purity of the a-cyanoacrylate monomer, and a method which in- volves decreasing the amount of anionic polymerization inhibitor to be added. Generally, the activity of anionic polymerization tends to be markedly affected by very small amounts of impurities, and in anionic polymerization of an a- cyanoacrylate monomer, an attempt has been made to minimize the amounts of impurities such as the presence therein of starting materials, catalyst and polymers of low degrees of polymerization in order to increase the setting time of the resulting product. However, because an or-cyanoacrylate monomer has unique anionic polymerizability, difficulties, such as the provision of a feasible apparatus, are encountered in obtaining an a- cyanoacrylate monomer of a high purity. Accordingly, this method of increasing the purity of the monomer is difficult to perform on a commercial scale. Usually, an anion polymerization inhibitor (stabilizer) such as sulfur dioxide, propane sultone or p-toluenesul- fonic acid is incorporated in a-cyanoacrylate-type ad- hesives to inhibit the anionic polymerization of the monomer due to the presence of water, etc. in the con- tainer during storage. The addition of the inhibitor serves to inhibit the anionic polymerization of the mon- omer during storage, but retards the setting time of the adhesive. An attempt has therefore been made to de- crease the amount of the anionic polymerization inhibi- tor and thereby to increase the setting time. This ap- proach, however, is limited in application because a reduction in the storate stability of the adhesive occurs as well. SUMMARY OE THE INVENTION Extensive investigations have been made on a method for accelerating the setting time of a-cyanoacrylate- type adhesives which is simple and which does not result in adverse effects. These investigations have led to the discovery that by incorporating a macrocyclic polyether or analogue thereof in an a-cyanoacrylate- type adhesive, the setting time of the a-cyanoacrylate- type adhesive becomes remarkably fast with little change in the storage stability from that of conventional a-cyanoacrylate-type adhesives occurring. According to the present invention, there is provided an adhesive composition comprising an a-cyanoacry- late and about 0.1 ppm or more of at least one macrocy- clic polyether compound or an analogue thereof. DETAILED DESCRIPTION OF THE INVENTION The a-cyanoacrylate-type adhesive of this invention is an adhesive containing as a main component an a- cyanoacrylate of the formula (I) 4,171,416 3 CN / CH2=C (1) COOR wherein R represents a straight chain or branched chain alkyl group having 1 to 12 carbon atom (which may be substituted with a substituent such as a halogen atom or an alkoxy group) a straight chain or branched chain alkenyl group having 2 to 12 carbon atoms, a straight chain or branched chain alkynyl group having 2 to 12 carbon atoms, a cycloalkyl group, an aralkyl group or an aryl group. Specific examples of the groups for R are a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a pentyl group, a hexyl group, an allyl group, a methallyl group, a crotyl group, a propargyl group, a cyclohexyl group, a benzyl group, a phenyl group, a cresyl group, a 2-chloroethyl group, a 3-chloropropyl group, a 2- chlorobutyl group, a trifluoroethyl group, a 2-methox- yethyl group, a 3-methoxybutyl group and a 2-ethox- yethyl group. . The a-cyanoacrylate monomer present can be a sin- gle cc-cyanoacrylate monomer or a mixture of two or more a-cyanoacrylate monomers can be employed. Generally, the a-cyanoacrylate monomer alone has insufficient properties as an adhesive, and other compo- nents such as the following may be added. (1) An anionic polymerizaton inhibitor. (2) A radical polymerization inhibitor. (3) A thickener. (4) Special additives such as plasticizers or heat stabi- lizers. (5) Perfumes, dyes, pigments, etc. A suitable amount of the a-cyanoacrylate monomer present in the adhesive composition is about 80 to 99.9% by weight preferably 90 to 99.9% by weight, based on the total weight of the adhesive composition. As stated hereinabove, an anionic polymerization inhibitor is added to the at-cyanoacrylate-type adhesive e.g., in an amount of about 1 to 1000 ppm based on the total weight of the adhesive composition, to increase the stability of the adhesive during storage, and exam- ples of known inhibitors are sulfur dioxide, aromatic sulfonic acids, aliphatic sulfonic acids, sultones, and carbon dioxide. Suitable examples of radical polymerization inhibi- tors include, for example, hydroquinone and hydroqui- none monomethyl ether. A radical polymerization in- hibitor is added e.g., in amount of about 1 to 5000 ppm based on the total weight of the adhesive composition, for the purpose of capturing radicals which are formed by light during storage. A thickener is added to increase the viscosity of the a-cyanoacrylate-type adhesive. The a-cyanoacrylate monomer generally has a low viscosity of about several centipoises, and therefore, the adhesive penetrates into porous materials such as wood and leather or adherends having a rough surface Thus, good adhesion strengths are difficult to obtain. Various polymers can be used as thickeners, and examples include poly(methy1 methac- rylate), a methacrylate-type copolymers, acrylic rub- bers, cellulose derivatives, polyvinyl acetate and poly- (a-cyanoacrylate). A suitable amount of thickener is generally about 20% by weight or less based on the total weight of the adhesive composition. 10 15 20 25 30 35 45 50 55 65 4 The plasticizers, perfumes, dyes, pigments, etc. may be added depending on use purposes in amounts which do not adversely affect the stability of the a-cyanoacry- late monomer. A suitable amount of the plasticizer is about 0.1 to 50% by weight, of the heat stabilizer is about 0.01 to about 5% by weight and of each of the perfume, the dyes and the pigments is about 0.01 to 5% by weight, based on the total weight of the adhesive composition. The crown compound used in this invention is a ge- neric term for macrocyclic polyether compounds. Since the formation of these compounds was confirmed in 1967 by C. J. Pedersen of E. I. du Pont de Nemours & Co., U.S.A., many compounds falling within this cate- gory have been discovered. The name “crown ethers” comes from their structural form. The most typical cyclic hexamer of ethylene oxide is called 18-crown-6. The numeral 18 denotes the number of atoms in the ring, and the numeral 6 denotes the number of oxygen atoms in the ring. 0(\o/NO < 0 0: you (l) 18-Crown-6 The oxygen atoms of the crown ether are aligned toward the interior of the ring, and byholding a metal- lic ion or an organic ion at the center of or at the upper or lower position of the ring by a coordination bond, crown ethers have a unique property of solubilizing inorganic salts (such as silver nitrate, silver chloride, etc.), alkali metal salts (such as potassium cyanide, po- tassium fluoride, etc.), and ammonium salts (such as ammonium thiocyanate, ammonium chloride, etc.) in aprotic or weakly polar solvents such as organic sol- vents (e.g., nitromethane, dimethyl sulfoxide, dimethyl- formamide, benzonitrile, etc.). Typical crown ether compounds and their structures are shown in James J. Cristensen, Delbert J. Eatough and Reed M. Izatt, Chemical Reviews, 1974, Vol. 74, No. 3, pages 351-384. All of these compounds can be used in this invention. Good results can be obtained also with other crown compounds having a macrocyclic poly- ether structure and capable of selectively complexing with a metallic ion or an organic ion. Crown ethers having nitrogen, sulfur, phosphorus, boron, etc. wholly or partly replacing the oxygen atoms, such as dithia-15-crown-5 S O C 0 D K/SJ O (2) Dithia-15-crown-5 can also be used in the present invention. In such case the second numeral designates the total number of oxy- genatoms and analogue atoms present. Analogues of the crown ethers whose ethylene group has been partly replaced‘ by benzo, cyclohexyl, decalyl, naphtho, me- 5 4,171,416 thylbenzo, butylbenzo, vinylbenzo, butylcyclohexyl, oxocyclohexane, methylene, trimethylene, tetramethyl- ene, or pentamethylene groups, and in which some of the hydrogen atoms of the ethylene group are replaced 5 by methyl, ethyl, propyl, butyl, acetyl, phenyl, etc., groups, oxygen or fluoro atoms, etc. can also be used in this invention. Typical examples of crown compounds that can be 10 used in this invention are listed below. (1) 18-Crown—6 (\O /\ CO 0) O O K/ O J , (2) Dithia-l5-crown—5 S 0 3 0 O 0 OJ’ K/ V (8) Dibenzo-30-crown-10 20 25 30 45 50 55 65 6 rmw CCO 0):) K/0K/O JJ ’ (9) Tribenzo-18-crown-6 M? cg O) COTE V (10) asym-Dibenzo-22-crown-6 (\O /\ 2 O O O O (/ ° 0 (l l) Dibenzo-l4—crown-4 O‘/\(i) cg, go (12) Dicyclohexyl-l8—crown-6 (\O /\ CCU OI) O 0 K,o J » (13) Dicyc1ohexyl—24—crown-8 CW0 /—\o/\O O: I) O O K’°\_/OJ’ (14) Cyclohexyl-12-crown-4 O 0 CCO 0) \__/ (15) 1,2-Deca1yl—l5-criown-5 fem 03:0 3. O O (16) 1,2-Naphtho—l 5-crown-5 4,171,416 7 8 -continued . -contmued rm 0 ° °>. 5 ffio 0 o » ( j , ¥—/ 0 O (17) 3,4,5-Naphthy1— 1 6-crown-5 \/ 10 (25) 1,2-Benzo-3,4-benzo—5-oxygen—20-crown-7 KN» /\ 0 0 O O Q j 15 CC I) 0 O O 0 K/OJ ’ K/o\/OJ Y (18) 1,2-Methylbenzo-l8—crown—6 11 (26) 2-Methyl—4-methyl-6-methyl-8-methyl-12-crown—4 o(\0 Waco on ,_ CH3 0 O KZO J ’ (21) 1,2-Vinylbenzo-15-crown-5 F03 O O cH2=cH—©: D _ O 0 \_/ or polymer thereof (22) [,2-Vinylbenzo-18-crown-6 (\o /\ O O CH2=CH—q D 0 O K/0 J ’ or polymer thereof (23) 1,2-tert-Butylcyclohexyl-18-crown-6 CH3 o(\O/we 3 um (24) 14-Crown-5 W°’\ 0 0 E D . °\/O (25) I,2-Benzo-3,4—benzo-5-oxygen-20-crown-7 4,171,416 21 22 -continued -continued CH3\ ,CH3 N I N P N Fm 5 913 III 0 0 / \ CH _N 3 ED: 3:) I /N: 0 0 P\N/ CH3\N/P CH3 K/°\/°\) ' 10 N/Cfi3 CH3 Cm \N u \ N: C"3\ / o / CH3 /N\ CH —N/ \N/ (26) 2-Methyl-4-methy1-6-methy1-8-methyl-12-crown—4 3 I CH CH \CH 15 CH3 3\N/ 3 3 , CH3 I < N El’ N CH 0 o N 3\E l CH3’ \CH3 0 0 CH3 20 (32) (\ S S /\ CH3 HN NH (27) 25 K/5 \_/S J ' o WSW (: 0) so 0 S jé K/S J ’ (34) 12-Crown-4 (28) 35 (O /\oj Q t E/SJ , (35) 21-Crown-7 40 /\ c/—\o—o> 0 (go a O N/\/0 N and k/ 0 & (36) 24—Crown-8 /\ (so) . 50 re 0 /N O B C D / O 0 av ‘r 5) b°\_/°J 55 CH3 /N CHSIN N\ CH3 IN CH3 N NICH 10. The composition of claim 1, wherein said compo- CH3 I I I 3 sition additionally contains an anionic polymerization 0 0 O , inhibitor and a radical polymerization inhibitor. l / 50 11. The composition of claim 10, wherein said com- B position further contains at least one of a thickener, a plasticizer, a heat stabilizer, a perfume, or a colorant. (31) 4: * I: :1: at 65