3,825,580 United States Patent Office Patented July 23, 1974 1. 2 3,825,580 cyanoacrylates having alkinyl groups (preferably having HEATRESISTANT ADHESIVE COMPOSITIONS 3 to 8 carbon atoms) include propargyl ox-cyanoacrylate, CONTAINING POLYMERIZABLE 1,1-dimethyl - 2 - propynyl ox-cyanoacrylate, 1-methyl-1- ALPHA-CYANOACRYLATES ethyl-2-propynyl ox-cyanoacrylate and 1-methyl-1-isobutyl Hiroyuki Kato, Isao Tsuzi, Kishiro Azuma, and Hide: 2-propynyl ox-cyanoacrylate; the ox-cyanoacrylates having maro Tatemichi, Nagoya, Japan, assignors to Toagosei alkenyloxyalkyl groups (preferably having 5 to 8 carbon Chemical Industry Co., Ltd., Tokyo, Japan atoms) include allyloxyethyl o-cyanoacrylates and allyl No Drawing. Original application Aug. 16, 1971, Ser. No. oxypropyl ox-cyanoacrylate; and the ce-cyanoacrylates hav 172,282, now abandoned. Divided and this application ing cycloalkenyl groups (preferably having 6 to 8 carbon Dec.Claims 13, 1972,priority, Ser. application No. 314,507 Japan, Aug. 18, 1970, O atoms) include 2-cyclohexenyl ox-cyanoacrylate and the 45/71,737 like. Among the above-mentioned ox-cyanoacrylates, allyl nt. C. CO7 c 12/18 c-cyanoacrylate and propargyl ox-cyanoacrylate are par U.S. C. 260-465.4 1. Claim ticularly preferable for use in the present invention, be cause of their being high in bonding strength at normal 5 temperature and in radical polymerizability. ABSTRACT OF THE DISCLOSURE The radical polymerizable ox-cyanoacrylates mentioned A heat-resistant adhesive composition comprising a in the above can be individually obtained according to a radical polymerizable ox-cyanoacrylate represented by the method in which a condensation product of a correspond formula, ing or -cyanoacetate with is depolymerized, CH=C(CN)COOR 20 or to a method in which an alkyl ox-cyanoacrylate such as wherein R is an alkenyl, alkinyl, alkenyloxyalkyl or cyclo methyl or ethyl ox-cyanoacrylate is subjected to ester ex alkenyl group, and at least 0.1% by weight based on the change reaction with a monohydric alcohol having such weight of the composition of a radical initiator. The said functional group as mentioned previously, e.g. allyl alco adhesive composition is not only instantaneously adhesive hol or propargyl alcohol. at room temperature but also has a sufficiently practical 25 The radical initiators used in the present invention are bonding strength even at such a high temperature as 150 not particularly limited in kind, and include known radi cal initiators such as, for example, various peroxides, azo C. or above. compounds and sulfur-containing compounds. Particular This is a Divisional Application of applicants' pending ly effective radical initiators are organic peroxides which 30 may be used alone or in admixture of two or more and application Ser. No. 172,282, filed Aug. 16, 1971, now which include, for example, ketone peroxides such as abandoned. methylethylketone peroxide and cyclohexanone peroxide; This invention relates to heat-resistant cyanoacrylate hydroperoxides such as cumene hydroperoxide and t-butyl type adhesive compositions, particularly those having in hydroperoxide; dialkyl peroxides such as dicumyl peroxide stantaneous adhesion. 35 and di-tert-butyl peroxide; peroxy-esters such as t-butyl Cyanoacrylates are cured by means of contained peroxybenzoate and t-butyl peroxy-isopropylcarbonate; in air and show strong instantaneous adhesion at room organic acid peroxides such as succinic acid peroxide and temperature to metals, glass and plastics, so that they have t-butylperoxymaleic acid; and diacyl peroxides such as heretofore been used for various purposes as main in benzoyl peroxide and the like. Dialkyl peroxides and per gredients of instantaneous adhesive compositions. 40 However, cyanoacrylate type adhesives are extremely oxy-esters are preferable. However, it is, of course, pos low in resistance to heat, water and impact. For example, sible to use other radical initiators, e.g. azo compounds methyl cyanoacrylate type and ethyl cyanoacrylate type Such as azobisisobutyronitrile, phenyl-azoally sulfone and adhesives which are commercially available at present are derivatives thereof; sulfur-containing compounds such as greatly deteriorated in bonding strength at temperatures 45 persulfate, sulfur and tetramethylthiuram above 100° C. Since cyanoacrylate type instantaneous ad mono- and di-sulfides; peroxide; and N-nitrile hesives usable at temperatures above 150 C. have not N-amyl compounds. been found as yet, the development of such adhesives is The radical initiators used in the present invention in strongly desired. clude various compounds and are not particularly limited An object of the present invention is to provide cyano 50 in kind, as mentioned above. In carrying out the present acrylate type instantaneous adhesive compositions which process on commercial scale, however, the use of radical are free from the above-mentioned drawbacks of the con initiators which show a half of 10 hours at tempera ventional cyanoacrylate type adhesives and which have tures of 80 to 140 C. is desirable in view of the stability sufficiently practical bonding strengths even at such high of the resulting compositions. temperatures as above 150 C. 55 The present compositions comprising the above-men With an aim to accomplish the above object, the present tioned radical polymerizable a-cyanoacrylates and radical inventors made extensive studies to find that a composi initiators may be incorporated, to such extents as not to tion comprising an ox-cyanoacrylate represented by the injure the later-mentioned characteristics of the present formula CH2=C(CN)COOR, wherein R is a radical po invention, with acidic stabilizers such as lymerizable functional group, e.g. an alkenyl, alkinyl, 60 and p-toluenesulfonic acid; polymerization inhibitors such alkenyloxyalkyl or cycloalkenyl group, (hereinafter, the as hydroquinone, benzoquinone and methoxyhydroqui said ox-cyanocrylate will be referred to as "radical po none; plasticizers such as dibutyl phthalate and tricresyl lymerizable ox-cyanoacrylate"), and a radical initiator can phosphate; monomers such as diallyl phthalate, allyl ac be a heat-resistant, instantaneous adhesive composition. rylate and triallyl phosphate; viscosity increasing poly Based on the above finding, the inventors have accom 65 mers such as polyacrylic acid esters and the like; and dyes plished the present invention. for coloration. It is also possible to incorporate therein As the above-mentioned radical polymerizable ox-cyano cyanoacrylates such as methyl cyanoacrylate, ethyl cyano acrylates which are used in the present invention, there acrylate, isobutyl cyanoacrylate and 2-ethylhexyl cyano may be shown various compounds. For example, the O acrylate; vinylidene ; and methylenemalonic acid cyanoacrylates having alkenyl groups (preferably having 70 esters such as dimethyl methylenemalonate and the like, 3 to 8 carbon atoms) include allyl ox-cyanoacrylate, meth which are capable of being anionically polymerized with allyl ox-cyanoacrylate and crotyl ox-cyanoacrylate; the or Water. 3,825,580 3 4. Characteristics of the present composition comprising Method for measurement of tensile bonding strength: the aforesaid radical polymerizable ox-cyanoacrylate and Two iron test pieces (in all the examples shown below, radical initiator are explained in further detail below. iron test pieces were used as substrates) having a cross The present composition can provide instantaneous ad sectional area of 5 mm. X 20 mm. were bonded to each hesion even at room temperature, and the adhesion speed other at room temperature by use of an adhesive compo thereof does not substantially change, in general, even if 5 sition, allowed to stand at room temperature for a definite the radical initiator is present. When coated at room tem period of time (ordinarily for 24 hours), and then heated perature on materials to be bonded, the composition is at a definite temperature for a definite period of time. anionic-polymerized due to water, which has adsorbed or Subsequently, the bonded test pieces were subjected to a adhered onto the surfaces of said materials, to become a O tensile tester maintained at the same temperature as the mixture of the radical initiator and a g-polymer formed heating temperature, and the bonding strength of the ad by the chain-opening of double bond present between hesive composition was measured at a tensile rate of 50 two carbon atoms in the o- and 6-positions of the ox-cyano mm./min. acrylate. In this case, a tensile bonding strength of 100 Reference Example 1 to 300 kg./cm. can be attained. When the bonded mate 5 A mixture comprising 494 g. of allyl alcohol, 681 g. rials are subjected to heating, the radical initiator con of cyanoacetic acid, 1,000 g. of and 35 g. of tained in said mixture decomposes to yield a radical, and p-toluenesulfonic acid was fed to a 3 liter glass flask such functional group as allyl or propargyl group radical equipped with a stirrer, a cooler and a water separator, polymerizes, whereby the above-mentioned 3-polymer is and then heated with stirring. When the inner tempera crosslinked to an infusible and insoluble three dimen 20 ture of the flask became 70° C., an azeotropic mixture sional polymer (y-polymer). Thus, the adhesive compo of formed water and the benzene distilled. After cooling sition of the present invention, when subjected to heat with the cooler, the azeotropic mixture was separated ing, takes the three dimensional structure, and hence is by means of the water separator into a water layer and a far more excellent in heat resistance than the known cya benzene layer. The benzene layer was returned to the noacrylate type adhesive. A specific technical idea of the 25 flask, and the water layer was removed out of the sys present invention resides in the finding of an instanta tem. After 5 hours, the temperature of the flask became neous adhesive composition capable of taking such struc 86° C., and the theoretical amount of water completed ture as mentioned above. In the above case, the concen the distillation. Subsequently, the benzene was removed tration of the radical initiator is preferably at least 0.1% by distillation at normal pressure and, after substantial by weight based on the weight of the adhesive composi 30 distillation of the benzene, the pressure was gradually re tion, so as to carry out sufficiently the crosslinking of duced to obtain under a pressure of 5 mm. Hg, 795 g. of such a 6-polymer as mentioned above. However, if the a colorless transparent liquid as a main fraction, b.p. concentration is more than 10% by weight, the propor tion of non-polymerizable material increases, and the ad 92°Elementary C., n.19 1.4422. analysis.-Calculated (percent): C, 57.6; hesion of the resulting composition tends to lower quick ly. Further, said 3-polymer is generally in a glass state H, 5.6; N, 11.2. Found (percent): C, 57.5; H, 5.6; N, at a temperature lower than 100° C., and hence, the 11.0.According to gas chromatography and infrared anal molecular movement of the polymer is difficult to cause. ysis, it was confirmed that the product was allyl cyano Accordingly, the crosslinking of said polymer is generally acetate. preferably effected at a temperature of 100 to 120° C. 40 Subsequently, 500 g. of trichloroethylene and 94 g. of Therefore, the radical initiators used in the present in paraformaldehyde were charged into a 1 liter glass re vention preferably have a decomposition temperature actor equipped with a stirrer, a dropping funnel, a cooler higher than said temperatures. As mentioned above, the and a water separator, and then heated to reflux the tri reason why dialkylperoxides and peroxyesters are prefer chloroethylene. Thereafter, a mixture comprising 375 g. able is that these radical initiators have in general such of the above-mentioned allyl cyanoacetate and 0.3 cc. of decomposition temperatures. Said radical initiators are suitable both in storage stability and cross-linking. piperidine was charged into the dropping funnel, and The adhesive composition of the present invention, like gradually dropped into the reactor over a period of 2 the known cyanoacrylate adhesive, is widely applicable hours. Water formed during the reaction azeotropically to metals, glass and plastics. When the present adhesive distilled together with the trichloroethylene. The water composition is used to bond, for example, 2 iron plates 50 layer was removed out of the system, and the trichloro at 20° C., a sufficient bonding can be attained within 1 layer was returned to the reactor. After carry minute after application of the composition, and the bond ing out the reaction for 6 hours, the trichloroethylene was ing strength thereof is sufficiently high even at such a removed under reduced pressure, whereby a reactive high temperature as 200° C. Considering the fact that viscous condensation product of the allyl cyanoacetate the known cyanoacrylate adhesive provides no substan 5 5 with the formaldehyde was left in the reactor. To this tial adhesion at an elevated temperature of more than condensation product were added 6 g. of p-toluenesulfonic 150° C., it is understood how excellent is the present acid, 4.5 g. of hydroquinone and 6 g. of phosphorus pent composition in heat resistance as compared with the oxide, and the resulting mixture was depolymerized un known adhesive. der the conditions of 150 to 170° C. and 7 to 5 mm. As mentioned above, the adhesive composition of the 60 Hg to obtain. 265 g. of a pale yellow liquid having a present invention has overcome the lack of heat resist boiling point of 89 to 95° C. The thus obtained liquid ance, which is a great drawback of the known instanta had an ability to bond iron test pieces in 2 minutes. This neous adhesive, and is substantially identical in instanta liquid was re-distilled to obtain 240 g. of a colorless trans neous adhesion and bonding strength at normal tempera parent fraction having a boiling point of 78 to 81 C./ ture with the known instantaneous adhesive. Moreover, 4 mm. Hg (uncorrected). The thus obtained liquid had when the present composition is subjected to heating, the a specific gravity of 1.046 (at 20° C.), a viscosity of 6.4 adhesive polymer contained in the composition takes a cps. (at 20° C.) and a refractive index of n20 1.4574. three dimensional reticular structure, so that the composi According to gas chromatography and infrared analysis tion becomes markedly excellent in chemical resistance. and from the results of elementary analysis set forth The present invention is illustrated in further detail 70 below, it was found that the liquid was allyl cyanoacrylate below with reference to examples, reference examples and of substantially 100% in purity. comparative examples. The measurement of adhesion was Elementary analysis.--Calculated (percent): C, 61.3; carried out according to the method shown below to cal H, 5.1;N, 10.2. Found (percent): C, 61.5; H, 5.5; N, 10.2. culate the tensile bonding strength of each adhesive com Using two iron test pieces, the liquid was measured in position. 75 tensile bonding strength, whereby the liquid could bond 8,825,580 5 6 the test pieces in 30 seconds and the bonding strength TABLE thereof after aging for 24 hours was 127 kg./cm. Heat- Bonding ing strength time (kg.f Reference Example 2 Trade name 1 Chemical name (hr.) cna.2) Perbutyl H------t-Butyl hydroperoxide------43 A mixture comprising 262 g. of propargyl alcohol, 398 Percumyl D Dicumyl peroxide------50 PernekN--- Methylethylketone peroxi 84 g. of cyanoacetic acid, 500 g. of benzene, 12.7 g. of Perbutyl Z-. t-Butyl peroxybenzoate.---- 25 p-toluenesulfonic acid and 6.4 g. hydroquinone was fed Perhexa H- Cyclohexanone peroxide------B 56 to a 2 liter glass flask equipped with a stirrer, a cooler Percumyl H------Cunene hydroperoxide------3 86 and a water separator, and then reacted at an azeotropic O it. Trademark of Nippon Yushi Co. temperature of the benzene and water formed during the reaction. The water distilled was removed out of the Sys Comparative Example 1 tem, and the benzene was returned to the flask. After re Each of the alkyl ox-cyanoacrylates shown in Table 2 acting for 12 hours, the reaction mixture was washed with was used, either singly or in combination with a radical a 5% aqueous caustic soda solution and then with Water, 5 initiator, to bond two iron test pieces and heated at 150 and the benzene was removed by distillation under nor C. for 1 hour, and the tensile bonding strength thereof at mal pressure. After removal of the benzene, a fraction 150° C. was measured. The results obtained were as Set having a boiling point of 88 to 89 C. was recovered un forth in Table 2. der a reduced pressure of 3 mm. Hg to obtain 250 g. of TABLE 2 a colorless transparent liquid having a specific gravity of 20 1.1356 (at 30° C.), a refractive index of 1.4520 (at 27 Peroxide Concen- Bonding C.) and a viscosity of 10.8 cps. (at 24° C.). According Alkyl group tration strength to infrared analysis and from the results of elementary of alkyl ox- (wt. (kg.f analysis, it was confirmed that the liquid was propargyl cyanoacrylate Name of compound percent) cm.2) Cyanoacetate. 0. O O 36 Elementary analysis.-Calculated (percent): C, 58.54; 0. 5 H, 4.09; N, 11.38. Found (percent): C, 58.58; H, 4.10; N, O 1.37. 3 O Subsequently, 32 g. of paraformaldehyde and 300 g. of 3. O trichloroethylene were charged into a 1 liter glass flask Example 2 equipped with a stirrer, a cooler, a dropping funnel and A composition comprising allyl ox-cyanoacrylate and a water separator, and then heated with stirrring to re flux the trichloroethylene. On the other hand, a mixture 3% by weight of Permek N was used to bond two iron comprising 123 g. of the above-mentioned propargyl test pieces, heated at 150° C. for such a period of time as cyanoacetate and 0.5 ml. of piperidine was charged into 35 shown in Table 3, and then subjected to tensile test at the dropping funnel, and then dropped into the flask over said temperature to examine the influence of heating time. a period of 1 hour. Water formed during the reaction The results obtained were as set forth in Table 3. formed an azeotropic mixture with the trichloroethylene, Comparative Example 2 and came to distill. The water layer was removed out of 40 Example 2 was repeated, except that each of methyl, the system and the trichloroethylene was returned to the ethyl and allyl ox-cyanoacrylate was used singly to bond flask. The reaction terminated in 3 hours, and substan tially the theoretical amount of water distilled. The prod the iron test pieces. The results obtained were as set forth uct was a trichloroethylene- and benzene-insoluble pale in Table 3. yellow solid formed by condensation of the propargyl TABLE 3 45 Tensile bonding cyanoacetate with the paraformaldehyde. This solid was strength (kg.icm.) in sufficiently washed with and then dried under heating time of - reduced pressure. To 120 g. of the dried condensation a-Cyano Radical product were added 2.2 g of p-toluenesulfonic acid, 0.6 acrylate initiator 1 hr., 3 hr. 5 hr. 7hrs Example 2------Allyl cy- Methylethyl- 84 72 65 68 g. of hydroquinone and 2 g. of phosphorus pentoxide, 50 Cyano- ketone and the resulting mixture was depolymerized under the acrylate. peroxide. Methyla- None.----...-...- 12 12 12 12 conditions of 150 to 180° C. and 3 mm. Hg to obtain cyano acrylate. 63 g. of a fraction having a boiling point of 62 C. This Ethyla- -...-- do------35 30 33 33 fraction was a colorless transparent liquid and confirmed Comparative Cyano Example 2. acrylate. to be propargyl cyanoacrylate according to infrared anal 55 Allyl or ----- do------5 12 12 12 ysis and from the results of elementary analysis set forth cyano below. acrylate. Elementary analysis.-Calculated (percent): C, 62.22; 1 Or less. H, 3.73; N, 10.37. Found (percent): C, 62.20; H, 3.75; Example 3 N, 10.38. 60 A composition comprising the propargyl-o-cyanoacry Using two iron test pieces, the thus obtained liquid was late prepared in Reference Example 2 and 3% by weight measured in tensile bonding strength, whereby the liquid of Permek N was used to bond two iron test pieces, could bond the test pieces in 30 seconds, and the bonding heated at 150° C. and 190 C. for a definite period of strength thereof after aging for 24 hours was 2.98 kg/ time and then subjected to tensile test at said tempera cm. 65 ture to examine the influence of heating time. The results Example 1 obtained were as set forth in Table 4. The allyl ox-cyanoacrylate prepared in Reference Ex TABLE 4 Bonding strength ample 1 was incorporated with 3% by weight of each of 70 (kg/cm.) at the organic peroxides shown in Table 1 to obtain a com Heating time (hr.) 150° C. 190° C. position. This composition was used to bond two iron 2 48 test pieces and then heated at 150° C. for 1 or 3 hours, 62 44 and the tensile bonding strength thereof was measured at 50 53 150 C. The results obtained were as set forth in Table 1. 75 55 44 3,825,580 7 8 Example 4 Example 7 A mixture comprising 80% by weight of allyl ox-cyano The same test as in Example 2 was effected at 173° C. acrylate and 20%, by weight of each of the alkyl ox-cyano The results obtained were as set forth in Table 5. acrylates shown in Table 8 was incorporated with 1% Comparative Example 3 by weight based on the weight of said mixture of Permek N to prepare a composition. This composition was used The same test as in Comparative Example 2 was to bond two iron test pieces, heated at 150° C. or 173° C. effected at 173° C. The results obtained were as set forth for 1 hour, and then measured in tensile bonding strength in Table 5. at 150 C. or 173° C. The results obtained were as set TABLE5 10 forth in Table 8. Tensile bonding strength (kg.fcm.2 in heating tinae of or-Cyano- Radical TABLE 8 acrylate initiator hr. 3 hr. 5 hr. 7 hr. 5 Tensile bonding Example 4----. Allyl az- Methylethy 57 62 82 71 Strength (kg.fcm.) cyanoac- ketone Alkyl group of alkyl am-mm rylate. peroxide. a-cyanoacrylate 50° C. 73° C. ethyla- None.------1.5 , 5 10 1.0 cyanoac Methyl------32 27 rylate. Ethyl------21 21 Ethyl o- ----. do------1.5 15 1.0 1.0 Isobutyl------20 15 Comparative cyanoac 20 Example 3. rylate. Allyl or ----- do------1,5 .5 .0 , 0 cyanoac rylate. Example 8 Example 5 25 A mixture of allyl ox-cyanoacrylate and 3% by weight of Permek N was incorporated with each of the additives A composition comprising allyl ox-cyanoacrylate and shown in Table 9 to prepare a composition. This com 3% by weight of Permek N was used to bond two iron position was used to bond two iron test pieces, heated test pieces, heated at temperatures within the range from 30 at 150 C. for 1 hour, and then measured in tensile bond 120° to 195 C. for 3 hours, and then subjected to tensile ing strength at 150° C. The results obtained were as set test at said temperature to examine the influence of heat forth in Table 9. ing temperature. The results obtained were as set forth in Table 6. Comparative Example 4 TABLE 9 Amount Example 5 was repeated, except that each of methyl, of ethyl and allyl ox-cyanoacrylates was used singly. The re additive incor- Tensile sults obtained were as set forth in Table 6. porated bonding - (wt. strength TABLE 6 40 Additive percent) (kg.fcn.2) Tensile bonding strength Allyl acrylate------2 64 (kg.lcm.9) at heating Dialyl phthalate----- 5 48 temperature of - Triallylphosphate------5 29 dinnethacrylate------5 53 oy-Cyano- Radical 120 150 173 195 Trimethylolpropane trimethacrylate. - 2 34 acrylate initiator o C. o C. o C. o C. Rikaitesin R.E.------5 51

45 Acrycon ?------2 60 Example 5-...--- Allyl cy- Methylethyl 85 7. 62 35 cyanoac- ketone 1 Trademark of Shin Nippon Rika Co., the main component: rylate. peroxide. Methyl or None.------28 O O 0 cyano-ac / -COO CHCH-CH rylate. O Ethyl ox------do------82 30 0 O 50 Comparative cyano-ac -COO CHCH-CH . Example 4. rylate. Allyl a------do------5 0 O 0 2 Trademark of Mitsubishi Rayon Co., the main component: poly Cyano-ac rylate. methylmethacrylate. 55 Example 6 Example 9 A composition comprising allyl ox-cyanoacrylate and 0 A composition comprising allyl ox-cyanoacrylate and to 10% by weight of Permek N was used to bond two 3% by weight of Permek N was used to bond iron test iron test pieces, allowed to stand at normal temperature 60 pieces and then subjected to tensile test before and after and 150° C. for 1 hour, and then measured in tensile heating. Subsequently, two polymers were recovered from bonding strength at 150° C. The results obtained were as the two kinds of test pieces which had been formed, set forth in Table 7. respectively, before and after heating, and the solubilities TABLE 7 of said polymers for were investigated to find 65 that the former polymer was soluble and the latter pol Tensile bonding strength (kg/cm2) ymer was entirely insoluble. at Example 10 Amount of Normal peroxide temper (wt. percent) ature 150° C. 70 A composition comprising propargyl cyanoacrylate and 127 5 0 to 3% by weight of Permek N was measured in bond 55 53 ing speed, bonding strength at room temperature, and 150 84 50 85 bonding strength at 150° C. after heating at 150° C. for 140 28 3 hours. The results obtained were as set forth in Table 130 0 75 10. 3,825,580 9 O TABLE 10 References Cited Paiyath UNITED STATES PATENTS --ee-ne 3,142,698 7/1964. Halpern et al. ------260 465.4 as Best St. 3,254,111 5/1966 Hawkins et al. ------260-465.4 (wt. percent) (Sec.) ature 50 C. 5 30 298 15 JOSEPH PAUL BRUST, Primary Examiner ge 829 60 60 220 62 : U.S. C., X.R. What is claimed is: 10 260-30.6R, 31.8 R, 464 1. Propargyl alpha-cyanoacrylate,