Colored Cyanoacrylate Adhesive composition

United States Patent [19] Nakata et al. [54] [75] [73] [211] [22] [51] [52] [58] COLORED CY ANOACRYLATE ADHESIVE COMPOSITION Inventors: Tiaki Nakata, Ibaraki; Noriyuki Kawazoe, Motomachi; Toshio Takenaka, Toyono, all of Japan Assignees: Sumitomo Chemical Company, Ltd.; Taoka Chemical Company, Ltd., both of Osaka, Japan Appl. No.: 417,155 Filed: Sep. 13, 1982 Int. Cl.3 ............................................ .. C08L 33/14 U.S. Cl. .................................. .. 524/717; 524/775; 524/850; 252/301.35 Field of Search ............. .. 524/717, 775, 850, 110; 252/ 301.35 [11] 4,405,750 [45] Sep. 20, 1983 [56] References Cited U.S. PATENT DOCUMENTS 3,699,076 10/1972 Thomsen at al. ................. .. 524/719 4,016,133 4/1977 Hyosu et al. . . . . . . . . . . .. 524/717 4,062,827 12/1977 Zollman ........................ .. 524/718 4,125,494 11/1978 Schoenberg et al. . . . . . . . . . .. 524/850 4,297,160 I0/-1981 Kusayama ...................... .. 156/331.1 FOREIGN PATENT DOCUMENTS 1192165 5/1970 United Kingdom. Primary Examiner—Lewis T. Ja.cobs Attorney, Agent, or Firm-—Wenderoth, Lind & Ponack [5 7] ABSTRACT a-Cyanoacrylate adhesives of fluorescent color having incorporated therein at least one member selected from C.I. Solvent Green 5; C.I. Acid Red 50 and C.I. Acid Red 52. 4 Claims, No Drawings 4,405,750 1 COLORED CY ANOACRYLATE ADHESIVE COMPOSITION The present invention relates to novel a-cyanoacry- late adhesives. More particularly, it relates to cyanoac- rylate adhesives colored with particular fluorescent dyes. An a-cyanoacrylate having the following formula (I) CN I CI-I;_=C—CO—OR (1) wherein R is a C1—C;5 alkyl, C2-C5 alkenyl, C1-C5 alkoxy C2-C4 alkyl, tetrahydrofurfuryl, phenyl or cy- clohexyl group, is a colorless and transparent liquid of a high fluidity at room temperature, and when coated in a thin film on the surface of substrate body and exposed to ambient atmosphere for several seconds, it rapidly hardens to form a strong solid film. Taking advantage of these properties, the compound described above is rap- idly applied between two materials, whereby the mate- rials are very strongly bonded in several to several ten seconds without applying pressure or heat. Because of such properties of a-cyanoacrylate, adhesives compris- ing this compound have been used as instantaneous adhesives for producing precision apparatus, electrical and electronic apparatus, etc. Further in recent years, their demand for domestic use is increasing, and they are in use for bonding various metallic articles, ceram- ics, glass articles, rubber articles, plastic articles and the like. While various performances including viscosity, bonding strength, setting time and so on are required for this type of adhesive depending upon intended uses, for example the kind of materials to be bonded, the form of bonding, a period of time necessary for bonding, the property of bonded materials and the like, and for satis- fying these requirements, a different kind of this type of adhesive composition is now placed on the market. For satisfying these requirements, for example, this type of adhesive comprises 10 to 50 ppm of sulfur diox- ide and 50 to 500 ppm of hydroquinone to elevate stor- age stability, and also comprises other stabilizers, poly- merization inhibitors, thickeners, diluents, plasticizers, etc. It is therefore very desirable to have a means to distinguish various kinds of these adhesive compositions at a glance. The well-known methods intended to distinguish the kind of these cyanoacrylate adhesives is to color the adhesives by the addition of particular dyes, for exam- ple 1-hydroxy-4-amino (or 4-arylamino)anthraquinones (British Pat. No. 1,192,165 and U.S. Pat. Nos. 3,699,076 and 4,062,827). These dyes, however, lower the bond- ing strength and storage stability of the cyanoacrylate adhesives. Generally speaking, a deep coloration is favorable for discrimination or distinction but causes the staining of materials to be bonded as well as lowering of the bond- ing strength and storage stability. Whereas, a light col- oration makes discrimination between coated "area and uncoated one impossible, so that parts to be coated remain uncoated in part, or more parts than required are coated, thereby impairing the bonding strength or caus- ing the staining of materials to be bonded. The present inventors extensively studied to improve the foregoing defects of the conventional coloration of 5 10 15 20 2 cyanoacrylate adhesives, and as a result, found that particular dyes having fluorescence well color the cya- noacrylate adhesives without impairing the bonding performances and storage stability thereof, and exhibit a very good visible distinguishabillity even in a light col- oration. An object of the present invention is to provide col- ored cyanoacrylate adhesives. Another object of the present invention is to provide cyanoacrylate adhesives which are easy to distinguish their kindsand coated areas from uncoated ones even in a light coloration. A further object of the present invention is to provide a method for giving fluorescence to cyanoacrylate adhe- sives and cyanoacrylate adhesives having fluorescence. According to the present invention, there is provided an adhesive composition comprising an a-cyanoacry- late having the formula, CN I CH2=C-C0---OR wherein R is a C1—C15 alkyl, C2-C5 alkenyl, C1-C5 alkoxy C2-C4 alkyl, tetrahydrofurfuryl, phenyl or cy- 5 clohexyl group, and at least one dye selected from the 30 35 40 45 50 55 60 65 group consisting of C.I. Solvent Green 5, C.I. Acid Red 50 and C.I. Acid Red 52. The a-cyanoacrylate usable in the present invention includes, for example, methyl a-cyanoacrylate, ethyl ct-cyanoacrylate, propyl ct-cyanoacrylate, butyl a- cyanoacrylate, amyl a-cyanoacrylate, hexyl a-cyanoa- crylate, cyclohexyl a-cyanoacrylate, benzyl a-cyanoa- crylate, phenyl a-cyanoacrylate, octyl a-cyanoacrylate, dodecyl a-cyanoacrylate, allyl a-cyanoacrylate, pro- pargyl on-cyanoacrylate, methoxyethyl a-cyanoacry- late, ethoxyethyl a-cyanoacrylate, furfuryl a-cyanoa- crylate, tetrahydrofurfuryl a-cyanoacrylate, chloro- ethyl a-cyanoacrylate, fluoroethyl a-cyanoacrylate, hexachloroethyl a-cyanoacrylate and the like. These a-cyanoacrylates may be used each alone or in combi- nation of two or more of them. The dyes used in the present invention, C.I. Solvent Green 5, C.I. Acid Red 50 and C.I. Acid Red 52, have structures represented by the formulae II, III and IV, respectively. These dyes are well soluble in the ct- cyanoacrylates in a bright yellow having a greenish fluorescence, a bright yellowish red having a greenish fluorescence and a bright bluish red having a greenish fluorescence; respectively. C.I. Solvent Green 5: 1 II 0. COOCH2—CH(CH3)2 (CH3)2CI-I--CI-I2OOC Q Q C.I. Acid Red 50: + 111 C2Hs-HN o ¢NH--CZH5 H3C: : :cé: ‘CH3 S03‘ ‘ SO3Na 4,405,750 3 -continued C.I. Acid Red 52: + IV (C2H5)2N N(C2Hs)2 5 ‘(EDT)’ C¢ S03‘ 10 SO3Na These dyes may be used each alone or as a mixture of two or more. The amount of these dyes added is 0.1 to 10000 ppm, 15 preferably 0.5 to 2000 ppm, based on the weight of the cyanoacrylate adhesives. When the amount is less than 0.1 ppm, both coloration and fluorescence show little effect. When the amount is more than 10000 ppm, the dissolution of dye becomes difficult, and an adverse effect is sometimes exerted on the bonding strength. Other dyes known for coloring cyanoacrylate may be used together so far as the result of the present inven- tion is not affected, and also in this case, the fluores- cence is maintained to effect the objects of discrimina- tion and visible distinction to a sufficient extent. In the dyes usable in the present invention are some- times contained basic substances and other impurities caused in the course of production, and therefore in such case, it is preferred to previously wash the dyes with a very dilute aqueous acid solution (e. g. 1% hydro- chloric acid), followed by drying and pulverizing. When such dyes are used without washing, they tend to affect the storage stability of the adhesives. The colored cyanoacrylate adhesives having fluores- cence of the present invention may contain various additives used in the conventional cyanoacrylate adhe- sives, for example, radical polymerization inhibitors such as hydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol, bisphenol A and the like (about 1 to about 10000 ppm, preferably 10 to 5000 ppm based on the weight of the adhesive), anionic polymeri- zation inhibitors such as S02, SOCl2, SO2Cl2, HF, N02, p-toluenesulfonic acid, methanesulfonic acid, propane- sultone, phosphoric acid, sulfuric acid, and the like. Further, for producing adhesive compositions having an increased viscosity, viscosity regulators such as methyl methacrylate polymer, vinyl acetate polymer, cellulose acetate isobutyrate, acrylic rubber, etc. may be incorporated in the adhesive. In addition to these, plasti- cizers may be added to give softness to hardened bond layer, and modifiers for giving impact strength and thermal resistance may be added. The colored cyanoacrylate adhesives having fluores- cence of the present invention have a beautiful yellow or red color having a greenish fluorescence, even when C.I. Solvent Green 5, C.I. Acid Red’ 50 or C.I. Acid Red 52 is used in small amounts. The adhesives of the present invention are colored without impairing bond- ing performances and storage stability, and therefore they are superior in the bonding performance and stabil- ity of a-cyanoacrylate itself to the conventional colored adhesives. Besides, the present adhesives are improved so that discrimination of their kinds and between coated areas and uncoated ones can easily be achieved even in a light coloration. The colored cyanoacrylate adhesives having fluores- cence of the present invention are suitable for bonding almost all the materials, i.e. rubbers, plastics, metals, 20 25 30 35 40 45 50 55 60 65 4 woods and the like, to which the conventional instanta- neous adhesives have been applied, and also preferably used, for example, in the fields of small-sized parts, construction of precision apparatus, thread-locking, sealing, artificial nail and the like. The present invention will be illustrated in more de- tail with reference to the following Examples. The test items and test methods in the Examples are as follows: VISCOSITY Measured at 20° C. by means of a Brookfield viscom- eter (cps). TENSILE SHEAR STRENGTH The test was carried out as follows according to “Test method for cyanoacrylate adhesives” described in JIS K-6861: A test piece according to JIS G-3141 (SPCC,‘cold-rolled steel sheet), 100 mmX25 mm>< 1.6 mm in size, was polished at the surface with Sand paper AA-150 and defatted with an acetone/toluene (1:1) mixed liquor; after coating the adhesive on the surface, a pair of the test pieces were superposed so that the bond area was 25 mm>< 12.5 mm, pressed against each‘ other by a force of about 2 kgf and aged as they were for 24 hours in a room of 20° C. and 60% RH; and then tensile shear strength was measured on a 5-ton capacity tensile tester, and a mean value of five tests was taken as tensile shear strength. SETTING TIME Test pieces were prepared for in the same manner as in the foregoing test method for tensile shear strength. After coating the adhesive so that the bond area was 25 mm>< 12.5 mm, the test pieces were superposed and pressed against each other by a force of about 2 kgf. According to the lapse of time, the bonded test piece was fixed at the upper end by jig, and a weight of 5 kg was put on the lower end of the test piece to apply tensile load. Thus, a period of time from the bonding to the time when the test piece no longer showed bonding break, was measured, and taken as a setting time. STORAGE STABILITY After storing at 70° C. for 7 days, the viscosity, tensile shear strength and setting time were measured in the manner described above. EXAMPLES 1 TO 5 AND COMPARATIVE EXAMPLES 1 AND 2 C.I. Solvent Green 5 in an amount (ppm) shown in Table 1 was dissolved in ethyl a-cyanoacrylate contain- ing 15 ppm of S02 and 500 ppm of hydroquinone. Ei- ther of the adhesive compositions obtained had a green- ish fluorescence and a bright yellow color. These adhe- sives were examined for bonding performances and storage stability in comparison with non-colored adhe- sives, and the results are as shown in Table 1. During these tests in which the colored adhesives and non-colored ones were coated on steel plate, each coated state was observed. With the former ones, the boundary of coating was clearly recognized irrespec- tive of the depth of coloration. While with the latter ones, the boundary of coating was hardly recognized. In the room of poor illumination, the boundary of coat- ing was little recognized for both the colored and non- colored adhesives, but on irradiation with black light, it 4,405,750 5 was able to be recognized very clearly for the colored adhesives because of a bright greenish fluorescence. 6 ethyl a-cyanoacrylate containing 15 ppm of S02 and 500 ppm of hydroquinone. The adhesives obtained had TABLE 1 Initial stage Storage stability Amount ‘Ten- Set- Ten- Set- of dye sile ting sile ting added Visco- shear time Visco- shear time Exp. No. (ppm) sity strength (sec) sity strength (sec) Example 1 5 2.5 202 45 3.0 196 60 Example 2 100 2.5 211 45 3.0 203 60 Example 3 500 2.5 207 45 3.0 208 60 Example 4‘ 500 60 201 70 110 204 70 Example 5 1000 2.5 212 50 3.0 210 60 Compar- None 2.5 205 45 3.0 219 60 ative Example 1 Compar- None 60 207 60 100 212 75 ative Example 2‘ Note: Each adhesive of Example 4 and Comparative Example 2 additionally comprises 10 parts by weight based on 100 parts by weight of the adhesive (PHR) of methyl methacrylate polymer. EXAMPLES 6 TO 12 AND COMPARATIVE EXAMPLES 3 AND 4 C.I. Acid Red 50 and C.I. Acid Red 52 in amounts as shown in Table 2 were dissolved in methyl a-cyanoa- crylate containing 15 ppm of S02 and 200 ppm of hy- droquinone. Either of the adhesive compositions ob- tained had a greenish fluorescence and a bright red color. ‘ The foregoing both dyes were treated before use as follows: Five grams of the crude product of them was dispersed in 200 ml of 1% aqueous hydrochloric acid solution, stirred for 30 minutes for washing, filtered, dried at 80° C. for 24 hours and then pulverized. The results about the bonding performances and stor- age stability are as shown in Table 2. The coated state on steel plate was observed, and it was found that either of the colored adhesives was clearly recognized, but with the non-colored ones, the boundary of coating was undistinguishable. In a dark place, both the adhesives were invisible, but on irradia- tion with black light, the colored ones only emitting a beautiful greenish fluorescence could clearly be recog- nized. a color as shown in Table 3, but fluorescence. These colored adhesives were examined and the re- sults are as shown in Table 3. 25 TABLE 3 Storage Compa- stability rative Tensile Example shear Visco- 30 No. Name of dye Color strength sity 1 Non Non 209 105 5 5-Amino-4-anilino— Blue 204 410 1,8—dihydroxy-anthra- quinone 6 l-Hydroxy-3-bromo-4- Red 151 110 35 amino-anthraquinone 7 2-(3—Hydroxy-2-quino- Yellow 140 105 linyl)-1H-indene- 1,3(2I-I)-dione 8 4-p-Anisidino-1- Purple 186 260 40 hydroxy-anthraquinone What is claimed is: 1. An adhesive composition comprising an a—cyanoa- crylate having the formula, TABLE 2 Amount of dye added Initial stage Storage stability Tensile Setting Tensile Setting C.I. Acid C.I. Acid Visco- shear time Visco- shear time Exp. No. Red 50 Red 52 Vsity strength (sec.) sity strength (sec.) Example 6 5 -— 2.5 201 45 3.0 196 45 Example 7 500 — 2.5 207 45 3.0 206 45 Example 8 1000 —— 2.5 203 45 3.0 207 45 Example 9 —- 5 2.5 198 45 3.0 g 207 45 Example 10 — 500 2.5 206 45 3.0 206 45 Example 11’ —- 500 60 199 60 130 200 60 Example 12 — 1000 2.5 201 45 3.0 203 45 Compa- — —— 2.5 205 45 3.0 209 45 rative example 3 Compa- -— — 60 207 60 100 200 60 rative example 4‘ Note: Each adhesive of Example 11 and Comparative Example 4 additionally comprises 10 parts by weight based on 100 parts by weight of the adhesive (PHR) of methyl methacrylate polymer. COMPARATIVE EXAMPLES 5 TO 8 Two hundred ppm of each of the dyes described in U.S. Pat. Nos. 3,699,076 and 4,062,827 was dissolved in 65 CN I CH2=C—C0-OR 4,405,750 7 wherein R is a C1—C15 alkyl, C2-C5 alkenyl, C1-C5 alkoxy C2-C4 alkyl, tetrahydrofurfuryl, phenyl or cy- clohexyl group, and at least one dye selected from the group consisting of C.I. Solvent Green 5, C.I. Acid Red 50 and C.I. Acid Red 52. 2. The adhesive composition according to claim 1, wherein the content of the dye is 0.1 to 10000 ppm based on the weight of the adhesive composition. 3. The adhesive composition according to claim 1, 10 15 20 25 30 35 40 45 50 55 60 65 8 wherein the composition additionally comprises atleast one member selected from the group consisting of poly- merization inhibitors, viscosity regulators, plasticizers and impact strength modifiers. 4. Materials bonded with the adhesive composition of claim 1.