2-Cyanoacrylate Adhesive Composition

_[22] Filed: United States Patent [19] Kimura et al. [54] 2-CYANOACRYLATE ADHESIVE COMPOSITION ’ [75] Inventors: Kaoru Kimura, Kuroishi; Kyoji Sugiura, Nagoya, both of Japan Toagosei Chemical Industry Co., Ltd., Tokyo, Japan [21] Appl. No.: 329,918 Dec. 11, 1981 [30] Foreign Application Priority Data Dec. 16, 1980 [JP] Japan .............................. .. 55-176502 [51] Int. Cl.3 .................... .. C08F 20/42; COSF 120/42 [52] U.S. Cl. .................................. .. 526/245; 526/ 206; 526/208; 526/292.2; 526/298 [58] Field of Search .......... .. 526/206, 208, 298, 292.2, 526/245 [73] Assignee: [56] References Cited U.S. PATENT DOCUMENTS 2,293,969 8/1942 Crawford et al. ................ .. 526/297 2,467,927 4/1949 Ardis .............. .. 526/297 2,776,232 1/1957 Shearer et al. 526/297 3,527,224 9/1970 Rabinowitz .. 526/297 3,564,078 2/1971 Wicker et al. 526/297 3,652,635 3/1972 Kawamura et a1. . 526/297 3,654,239 4/1972 Mclntire et al. 526/297 3,692,752 9/1972 Setsuda et al. 526/297 3,836,377 9/1974 Delahunty‘ ..... .. 526/297 4,139,693 2/1979 Schoenberg ...................... .. 526/297 Primary Examiner—Harry Wong, Jr. [11] 4,393,183 [45] Jul. 12, 1983 Attorney, Agent, or Firm—Cooper, Dunham, Clark, Griffin & Moran [57] ABSTRACT An adhesive composition comprising 2-cyanoacrylate and at least one compound selected from the group consisting of R1—CH2OH, R1 R1 \ \ CHOH, R2-—C0H, / R2 R3 R1-4-CH0, R1———CHO hydrate, R1 R1 \ \ C=O, C=O hydrate, / R2 R2 pentafluorophenol, hexachloroacetone, hexachloroace- tone hydrate, chloral and chloral hydrate as cationic- polymerization inhibitor. In the above formulas, R1 is a fluorinated alkyl or aryl group having up to 12 carbon atoms, and R2 and R3 are fluorinated or non-fluorinated alkyl or aryl groups having up to 12 carbon atoms. The above adhesive composition has an excellent storage stability and an improved bonding strength. 11 Claims, 1_‘Io Drawings 4,393,183 1 2-CYANOACRYLATE ADHESIVE COMPOSITION The present invention relates to a 2-cyano acrylate adhesive composition. More particularly, it relates to a 2-cyanoacrylate adhesive composition having an excel- lent storage stability and an improved bonding strength. 2-Cyanoacrylate adhesives are reactive adhesives which comprise 2-cyanoacrylate monomer as the main component, and therefore, they are often cured during storage in their containers owing to the radical or ani- onic polymerization of 2-cyanoacrylate monomer. In order to obtain a good storage stability, a polymeriza- tion inhibitor is added to them as a stabilizer. As inhibi- tors for the radical polymerization of 2-cyanoacrylate monomer, there are used hydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol, Bisphenol A and the like. The inhibitor is added in the range of 1 to 10,000 ppm in order to prevent the radical polymeriza- tion during storage at room temperature. On the other hand, the anionic polymerization is initiated by a very small amount of a basic substance such as water, an amine, ammonia or the like incorpo- rated during storage. For preventing the viscosity in- crease and gelation resulting from this anionic polymer- ization, it is known that S02, S03, SOCI2, SO2Cl2, HF, N02, p-toluenesulfonic acid, methanesulfonic acid, pro- panesultone, phosphoric acid, sulfuric acid and the like are effective. However, the addition of these anionic- polymerization inhibitors causes the coloring of adhe- sive composition with time and the prolongation of the setting time thereof with time. Accordingly, anionic- polymerization inhibitors of better quality which do not cause the above problems have been desired in this field. In view of the above need, the present inventors have made research on stabilizers which can prevent the anionic polymerization of 2-cyanoacrylate monomer. As a result, it has been found that a compound having an active hydroxyl group or a group which can be converted into an active hydroxyl group is an effective anionic-polymerization inhibitor unlike the conven- tional one. ‘ According to this invention, there is provided an adhesive composition which comprises a 2-cyanoacry- late and a compound having an active hydroxyl group or a group which can be converted into an active hy- droxyl group. The present invention has enabled the prevention of the reduction in the adhesive properties of 2-cyanoacrylate monomer with time during storage experienced with conventional anionic-polymerization inhibitors, namely the prevention of the coloring with time and the prolongation of setting time with time. Further, the adhesive composition according to the present invention has not only excellent storage stabil- ity, but also an improved bonding strength. The present anionic-polymerization inhibitor for 2- cyanoacrylate monomer which has an active hydroxyl group or a group which can be converted into an active hydroxyl group is a compound possessing in the mole- cule fluorine or chlorine atoms and a hydroxyl, alde- hyde or carbonyl group. Specifically, the following compounds are included: 10 15 20 25 30 35 40 45 50 55 65 2 R1 R1 (1) \ \ R1‘-CH7_OH, CHOH, R2“COH; / / R2 R3 (2) R1—CHO, R1—CHO hydrate; (3) C=O hydrate; R2 (4) pentafluorophenol; (5) hexachloroacetone, hexachloroacetone hydrate; and (6) chloral, chloral hydrate. In the above formulas, R1 is a fluorinated alkyl or aryl group having up to 12 carbon atoms; and R2 and R3 are fluorinated or non-fluorinated alkyl or aryl groups hav- ing up to 12 carbon atoms. Among the above compounds, the compounds (1), (2), (3), (4) and (5) are preferred, and more preferable are the compounds represented by the formulas, R] R1 R1 \ \ \ R2—COI-I, C=O, C=O hydrate, / / / R3 R2 R2 and pentafluorophenol. Specific examples of these compounds include triflu- oroethanol, 1H,1H-pentafluoropropanol, 1H,lH-hepta- fluorobutanol, lH,1H-nonafluoropentanol, 1, l, 1-tri- fluoroisopropanol, hexafluoroisopropanol, octafluoro- sec-butanol, perfluoro-tert-butanol, hexafluoro-tert- butanol, 2-trifluoromethylpropanol-2, 1-ch1oro- 1,1,3,3,3-pentafluoro-2-propanol, 3,3,4,4,4-penta- fluorobutanol-2, 3,3,4,5,5,5-hexafluoro-2-methylpen- tanol-2, 1H,1H,5H-octafluoro-1-pentanol, 1H, lH-pen- tadecafluorooctanol-1, trifluoroacetaldehyde, tri- fluoroacetaldehyde hydrate, heptafluorobenzaldehyde, 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, pentafluoroben- zyl alcohol, hexafluoroacetone, hexafluoroacetone hy- drate, trifluoromethyl trichloromethyl ketone, penta- fluoroethyl ethyl ketone, pentafluorophenyl methyl ketone, methyl heptafluoropropyl ketone, hexafluoro-2- phenylisopropanol, hexafluoro-2-(p-tolyl)isopropanol, pentafluorophenol, hexachloroacetone, hexachloroace- tone hydrate, sym-dichlorotetrafluoroacetone and sym- dichlorotetrafluoroacetone hydrate. Among the above specific compounds, preferable are trifluoroethanol, 1H,1H—pentafluoropropanol, 1, 1, l-tri- fluoroisopropanol, hexafluoroisopropanol, octafluoro- sec-butanol, perfluoro-tert-butanol, hexafluoro-tert- butanol, 2-trifluoromethylpropanol-2, 3,3,4,4,4-penta- fluorobutanol-2, trifluoroacetaldehyde, tri- fluoroacetaldehyde hydrate, heptafluorobenzaldehyde, pentafluorobenzyl alcohol, hexafluoroacetone, hexa- fluoroacetone hydrate, trifluoromethyl trichloromethyl ketone, pentafluorophenyl methyl ketone, methyl hep- tafluoropropyl ketone, pentafluorophenol, hexachlor- oacetone, and sym-dichlorotetrafluoroacetone. More preferable are hexafluoroisopropanol, perfluoro-tert- butanol, trifluoroacetaldehyde, trifluoroacetaldehyde hydrate, hexafluoroacetone, hexafluoroacetone hydrate and pentafluorophenol. 4,393,183 3 These compounds possess a hydroxyl group activated by electron-attractive fluorine or chlorine atoms, or, in the case of aldehyde and ketone compounds, they can be converted into compounds having active hydroxyl group as shown in the following formulas, by combin- ing or reacting with a very small amount of water or an alcohol present in the adhesive composition: OH H 0 / CF3CHO 2% CF3CH OI-I c H OH CF3CHO -—2—5—-9 CF3(|2H--OH OCZH5 /on H 0 CF3CCH3 2% (CF3)2C ll 0 OH The above fluorinated or chlorinated compounds have the nature that they become acidic because of the dissociation of hydroxyl groups into H+ due to the electron attractive property of the fluorinated or chlori- nated alkyl or aryl groups. Therefore, these compounds prevent the anionic polymerization of 2-cyanoacrylate monomer during storage, and accordingly, no reduc- tion of its bonding performance with time takes place. The 2-cyanoacrylate adhesive composition according to the present invention can be obtained by adding at least one compound selected from the above com- pounds (1) to (6) to a 2-cyanoacrylate monomer, prefer- ably in a quantity of 0.1 to 10,000 ppm, more preferably 1 to 6,000 ppm. In this case, the above compound may also be used in combination with a conventional anion- ic-polymerization inhibitor such as S02, S03, p-toluene- sulfonic acid, propanesultone or the like. Representative examples of the 2-cyanoacrylate mon- omer, which is the main component of the adhesive composition according to the present invention, include methyl 2-cyanoacrylate, ethyl 2-cyanoacrylate, propyl 2-cyanoacrylate, allyl 2-cyanoacrylate, butyl 2-cyanoa- crylate, heptyl 2-cyanoacrylate, hexyl 2-cyanoacrylate, octyl 2-cyanoacrylate, decyl 2-cyanoacrylate, dodecyl 2-cyanoacrylate, 2-chloroethyl 2-cyanoacrylate, methyl Cellosolve 2-cyanoacrylate, ethyl Cellosolve 2-cyanoa- crylate, butyl Cellosolve 2-cyanoacrylate, benzyl 2- cyanoacrylate, phenyl 2-cyanoacrylate, trifluoroisopro- pyl 2-cyanoacrylate, and the like. The adhesive composition according to the present invention may also contain a radical polymerization inhibitor in a quantity of l to 10,000 ppm, preferably 10 to 5,000 ppm. For example, hydroquinone, hydroqui- none monomethyl ether, catechol and pyrogallol are effective. When it is desired to thicken the present adhesive composition, a thickener such as methyl methacrylate polymer, vinyl acetate polymer, cellulose acetate isobu- tyrate, acrylic rubber or the like may also be dissolved in a proportion of several percent. Other additives such as plasticizers for imparting flexibility to cured adhesive layers, modifiers for im- parting impact resistance and heat resistance and dyes and pigments for identification of coating may also be added. Because of containing a small amount of at least one of the compounds (1) to (6), the adhesive composition l0 15 20 25 30 35 45 50 55 60 65 4 according to this invention exhibits aniexcellent storage stability and simultaneously has a higher bonding strength than the conventional adhesive compositions. The adhesive composition according to this invention has a high setting rate (namely a short setting time) and is suitable for instantaneous adhesion of most materials such as rubbers, plastics, metals, wood and the like. The composition is used, for instance, for assembling small parts. This invention is explained in more detail below re- ferring to Examples. However, this invention should not be understood to be limited to the Examples. In the Examples and Comparative Examples, parts are by weight unless otherwise specified. Examples 1 to 17 and Comparative Example 1 To 100 parts of ethyl 2-cyanoacrylate were added 0.05 part of hydroquinone and 0.002 part of each of the inhibitors shown in Table 1. Each of the adhesive com- positions thus obtained was charged into a polyethylene container and then subjected to heating tests at 60° C. Results are shown in Table 1. TABLE 1 Tensile shear strength of bond (iron) (Kgf/cmz) Setting time (iron) (sec) Heat gelation test at Inhibitor 60° C. Ex- ample 1 CF3Cl-I201-I 10 200 Stable for more than 35 days Stable for more than 35 days Stable for more than 46 days 2 (CF3)2CHOH 10 205 3 (CF3)3COH 10 205 4 CH3 10 200 Stable for I more than CF3"CHOH 35 days 5 CF3CF2Cl-I201-I 10 200 Stable for more than 35 days Stable for more than 35 days Stable for more than 43 days Stable for more than 35 days Stable for more than 50 days Stable for more than 35 days Stable for more than 40 days Stable for more than 35 days Stable for more than 43 days Stable for more than 45 days 6 HCFZCFZCI-I201-I 10 210' 7 C5F5Ol-I 10 210 3 C5F5CH20H 10 220 9 (CF3)2C=O hydrate 10 220 10 (cc13-)2—c=o 10 200 ll CF3CHO hydrate 10 210 12 10 CCl3CI-IO 190 13 C5F5CHO 10 195 14 (cc11=2-)z—c=o hydrate 10 200 4,393,183 5 6 TABLE 1-continued TABLE 3 Tensile Tensile shear shear Setting strength Heat Strength Heat‘ time ‘ of bond gelation 5 al Seniflg 0f bond 8913*)“ (iron) (1,-oh) test gt fsddition time (iron) test at Inhibitor (sec) (Kg,-/cmz) 60- C_ Inhibitor (sec) (Kgf/cmz) 60' C. is C3F7CCH3 10 200 Stable for _1:3_X2I2L1