Novel alpha-cyanoacrylate and adhesive composition.

EP 0 470 722 A1 0’ European Patent Office Européiisches Patentamt @ Publication number: 0 Office européen des brevets @ EUROPEAN PATENT APPLICATION @ Application number: 913066593 @ Int. C|.5: C07C 255/23, C09J 4/04 @ Date of filing: 22.07.91 Priority: 07.08.90 JP 207679l90 @ Inventor: Mikuni, Hiroyuki 2-25-3 Aihara Sagamihara-shi, Kanagawa-ken (JP) Inventor: Chikusa, Toshiyuki 2295-2 Kobiki-cho Hachioji-shi, Tokyo (JP) Date of publication of application : 12.02.92 Bulletin 92/07 Designated Contracting States: DE FR GB Representative : Cropp, John Anthony David et al MATHYS & SQUIRE 10 Fleet Street @ Applicant: THREE BOND co., LTD. "°"°'°"’ E°4Y1AY(GB) 1456, Hazama-cho Hachioji-shi Tokyo (JP) Novel alpha-cyanoacrylate and adhesive composition. @ A novel neopentyl cx-cyanoacrylate is provided. It has superior adhesive properties even at high temperatures and whitening-preventing property. Jouve, 18, rue Saint-Denis, 75001 PARIS 10 15 20 25 30 35 40 45 50 55 EP 0 470 722 A1 Background of the Invention The present invention relates to a novel on-cyanoacrylate and a cyanoacrylate-based adhesive composition containing same. on-Cyanoacrylates such as methyl or-cyanoacrylate and ethyl on-cyanoacrylate are polymerized and cured rapidly by the action of a small amount of water present on the surface of a material to be bonded and afford an adhesive force of an extremely high strength, so are widely used as room-temperature one-pack type instan- taneous adhesives for the bonding of metals, plastics, rubber, wood and the like. As on-cyanoacrylate there are known propyl on-cyanoacrylate, allyl on-cyanoacrylate, propargyl oc-cyanoac- rylate, 2,2,2-trifluoroethyl on-cyanoacrylate, 2,2,3,3-tetrafluoropropyl or-cyanoacrylate, 2-methoxyethyl oc- cyanoacrylate, 2-ethoxyethyl a-cyanoacrylate and the like in addition to the above mentioned methyl and ethyl a-cyanoacrylates. Generally, in the case where an on-cyanoacrylate is used as an adhesive, a portion thereof volatilizes and is polymerized by water contained in the air and adheres as white powdertothe surrounding portion of a bonded part (whitening phenomenon), thus impairing the appearance of the bonded material. When used in the assem- bly of electric and electronic parts, the volatilized monomer contaminates the contact portion and causes defec- tive contact, or cures in a moving part, thereby causing malfunction. Moreover, the thermal stability of the cured product is not sufficient and the bonding strength is reduced rapidly over 100°C. It is known that oc-cyanoacry- lates having an unsaturated bond in the ester portion have improved thermal stability. In this case the cured or adhered portion is heat treated at an appropriate temperature (100°C - 150°C) in order to improve the thermal stability. However, the adhesive properties at high temperature are not improved. It is the object of the present invention to overcome the above mentioned drawbacks of the prior art. More concretely, it is the object of the present invention to provide a novel compound having superior adhesive properties as an instantaneous adhesive and superior whitening-preventing property and thermal stability including high temperature adhesive properties. Summary of the Invention The present invention resides in a novel neopentyl on-cyanoacrylate having the chemical structural formula: CN / CH 3 \ l COZCHZCI-CH3 CH3 CH2=C and an adhesive containing the above compound as an essential component. Detailed Description of the Invention The novel compound, neopentyl or-cyanoacrylate exhibits excellent instantaneous adhesive properties. It has a melting point of 40°C and is a solid at a room temperature It can be used by itself as hot-melt type instan- taneous adhesive and also as a liquid instantaneous adhesive in admixture with one or more conventional cyanoacrylates in the same manner as conventional instantaneous adhesives. The instantaneous adhesive containing neopentyl or-cyanoacrylate as an essential component does not induce the whitening phenomenon and is superior in thermal stability, especially in high temperature-bonding strength. Neopentyl on-cyanoacrylate may be used alone or in combination with one or more conventional oc-cyanoac- rylates. Such conventional on-cyanoacrylates are those represented by the following general formula: 10 15 20 25 30 35 40 45 50 55 EP 0 470 722 A1 C—O—R ll 0 wherein R is a hydrocarbon group such as alkyl, alkenyl, or alkynyl, or an alkoxy hydrocarbon group such as alkoxyalkyl. Examples are methyl on-cyanoacrylate, ethyl on-cyanoacrylate, isopropyl or-cyanoacry|ate,those wherein R is alkoxyalkyl, e.g. 2-methoxyethyl on-cyanoacrylate and 2-ethoxyethyl or-cyanoacrylate, those whe- rein R is alkenyl, e.g. allyl or-cyanoacrylate, and those wherein R is alkynyl, e.g. propargyl or-cyanoacrylate. When using conventional cyanoacrylates in combination with neopentyl or-cyanoacrylate, the latter is pref- erably in an amount of 85 wt% or less, more preferably 5 to 85 wt% based on the weight of adhesive compo- nents. If the amount of neopentyl on-cyanoacrylate is more than 85 wt%, the composition becomes a solid at a room temperature (i.e. 20°C). Neopentyl on-cyanoacrylate of the present invention may be prepared by the following reactions. Neopentyl or-cyanoacetate having the following structural formula: IL‘ 3 -CH3 I NCCHZCOZCI-I2 O-—O-—O E is prepared and then it is reacted with formaldehyde or paraformaldehyde in the presence of a basic catalyst to produce a condensation polymer, and then the condensation polymer thus produced is heat-depolymerized or thermally decomposed to produce neopentyl or-cyanoacrylate. Neopentyl on-cyanoacrylate thus obtained is a solid at a room temperature but it is desirable to add thereto a stabilizer in order to store it more stably. Examples of such stabilizer include, as anionic polymerization inhibi- tors, sulfurous acid (S02), sultone compounds, organic sulfonic acids, mercaptans, trifluoroacetic acid, and fluoroboric acid, and as radical polymerization inhibitors, quinones, catechol, pyrogallol, and 2,6-di-t-buty|- phenol. The amount of these stabilizers differs depending on the respective inhibiting abilities, but is preferably in the range of 1 to 10,000 ppm, more preferably 10 to 1,000 ppm, relative to the monomer. The following examples are given to illustrate the present invention in more detail. The "part" and "%" in the following description are all by weight. Example 1 (Preparation of Neopentyl or-Cyanoacetate) 51g (0.6 mole) of cyanoacetic acid, 74g (0.84 mole) of neopentyl alcohol, 1g of sulfuric acid and 100g of toluene were reacted under reflux and water produced was removed by azeotropic distillation. Thereafter, the mixture thus produced was cooled to room temperature and filtered to remove insoluble matter. The filtrate was washed with water and dried overnight with magensium sulfate. Then, the desiccant was filtered off and the solvent was removed under reduced pressure, followed by vacuum distillation to afford 87.1g of neopentyl oc- cyanoacrylate (b.p. 79 - 81°C/3mmHg, yield 94%). 1R (neat)cm-1: 2262, 1751 60MHz 1H-NMR (CDCI3/TMS) 5(ppm): 3.87 (s, 2H), 3.46 (s, 2H), 0.97 (s, 9H) 90MHz 13C-NMR (CDCI3) 8(ppm): 162.91, 113.06, 75.41, 31.03, 25.86, 24.30 (Preparation of Neopentyl or-Cyanoacrylate) 46.5 (0.3 mole) of neopentyl or-cyanoacetate, 8.1g (0.27 mole) of paraformaldehyde, 140g of toluene and 3 10 15 20 25 30 35 40 45 50 55 EP 0 470 722 A1 46.5 mg of triethylenediamine were reacted together under reflux and water was removed by azeotropic distil- lation. Then, 23.5g of dioctyl phthalate, 0.465g of hydroquinone and 0.93g of phosphorus pentoxide were added and depolymerization allowed to take place at 150 - 210°C under a reduced pressure to afford 21.65g of crude neopentyl or-cyanoacrylate. Red istillation thereof afforded (8.3g of neopentyl on-cyanoacrylate (b.p. 65 - 67°C/2 mmHg, m.p. 40 - 41°C, yield 36%). 60MHz0+NMR(CDGyTMS) 5(ppm): 7.01 (s, 1H), 6.61 (s, 1H), 3.95 (s, 2H) 1.20 (s, 9H) 90MHz”GNMR(CDGg &ppmx160J4,14218,11644,11408,7546,3L22,2595. Example 2 Adhesives were prepared by mixing neopentyl on-cyanoacrylate (NPCA) and ethyl a-cyanoacrylate (ECA) as a conventional on-cyanoacrylate in such proportions as shown Table 1 below and then incorporating therein 20 ppm of BF3- ethyl ether complex and 1,000 ppm of hydroquinone. Their adhesive properties are as set forth in Table 1. \ Table 1 Adhesive Properties (iron /iron) Tensile Shear Hot: Tensile Strength Shear Strsngth (kgf/cm ) (kgf/cm ) Mixing Ratio whitening (parts) NPCA/ECA 1/100 whitened (Compara- tive example) slightly whitened 20/80 slightly whitened 40/60 60/40 not whitened so/20 not whitened 100/o not whitened Example 3 Adhesives were prepared by mixing neopentyl or-cyanoacrylate (NPCA) and allyl or-cyanoacrylate (ACA) as a conventional on-cyanoacrylate in such proportions as shown in Table 2 belowand then incorporating therein 20 ppm of BF3- ethyl ether complex and 1,000 ppm of hydroquinone. Their adhesive properties are as set forth in Table 2. 10 15 20 25 30 35 40 45 50 55 EP 0 470 722 A1 Table 2 Adhesive Properties (iron/iron) Tensile Shear Hot Tensile Strengta Shear Strength (kgf/cm ) (kgf/Cm 3 Mixing Ratio (parts)" whitening NPCA/ECA O/100 (Compara- tive example) whitened 20/80 slightly whitened 40/60 slightly whitened 60/40 not shitened 80/20 not whitened I'10t whitened Example 4 Adhesives were prepared by mixing neopentyl on-cyanoacrylate (N PCA) and 2-ethoxyethyl a-cyanoacrylate (EECA) as a conventional on-cyanoacrylate in such proportions as shown in Table 3 below and then incorporat- iwmawfl0wmdBfiemwwmmmwaam10%pmmmwmwmmeTmkMmmmpmmm%am as set forth in Table 3. 10 15 20 25 30 35 40 45 50 55 EP 0 470 722 A1 Table 3 Adhesive Properties (iron/iron) Mixing Ratio (parts) Tensile Shear Hot Tensile Whitening . Strengt Shear Strength NPCA/ECA (kgf/cm ) (kgf/cm ) slightly whitened O/100 (Compara- tive example) slightly whitened 20/80 not whitened 40/60 not whitened 60/40 not whitened 80/20 not whitened 100/0 Comparative Example The adhesive properties of neopentyl on-cyanoacrylate were compared with those of n-amyl oc-cyanoacry- late (n-AmCA) and iso-amyl on-cyanoacrylate (i-AmCA). The results are as set forth in Table 4. 10 15 20 25 30 35 40 45 50 55 EP 0 470 722 A1 Table 4 Adhesive Properties ( iron / iron) Tensile Hot Tensile Shear Shear Strengtg Strengta Chemical 5 true ture Cyanoacrylate CH2=C lxozcsnu _7fi_- cH2=q CH3 co2cH2ca2¢H cu; Testing Method Tensile Shear Strength: Measured at 25°C after aging 24 hours at 43 : 1°C, 60 i 2% RH, according to JIS K6861. Hot Tensile Shear Strength: Measureds at 150°C x 1 hr after agint 24 hours at 43 : 1°C, 60 i 2% RH, according to JIS K6861. Whitening: A schale which had been made clean was placed on black paper, and each adhesive was dropped one drop into the schale. After standing 24 hours at 43°C, 60% RH, the presence or the state of whitening was checked. Claims 1. 2. Neopentyl on-cyanoacrylate having the formula CN /’ CH2=C CH3 \ ‘ I ‘ cozcnzc-CH3 CH3 An instantaneous adhesive comprising as an essential component neopentyl oz-cyanoacrylate having the 7 10 15 20 25 30 35 40 45 50 55 EP 0 470 722 A1 formula. /CN CI-I =C H 2 3 \ ‘i COZCHZCI‘-CH3 CH3 An instantaneous adhesive as set forth in claim 2, further containing a conventional on-cyanoacrylate. An instantaneous adhesive as set forth in Claim 3 wherein said conventional on-cyanoacrylate is a liquid compound at a room temperature. An instantaneous adhesive as set forth in Claim 3 or Claim 4 wherein the amount of the neopentyl oc- cyanoacrylate is 5 to 85 wt% based on the weight of adhesive components. .0) EPO FORM I503 (012 (P1301) EP 0 470 722 A1 European Patent Office EUROPEAN SEARCH REPORT Application Numbq EP 91 30 6659 A Place of reach Die of unaoletlon of the reset THE HAGUE 19 MJVEMBER 1991 : theory or principle underlying the invention : earlier patent document, but published on, or after the filing date : document cited in the application ' documait cited for other rasons "UO> -¢ DOCUMENTS CONSIDERED TO BE RELEVANT Citation of document with indication, where appropriate, of relevant pnges l.lS—A-3 142 698 (B, D. HALPERN) * the whole document * GB—A—1 158 997 (EASTMAN KODAK) * column 1, l1ne11 -l1ne13 * * page 2, column 1, line 11- line 27 * * examples 2,5 * The present search report has been drawn up for In claims CATEGORY OF CITED DOCUMENTS particularly relevant if taken alone : particularly relevant if combined with another document of the same category 2 technological background : non—writta disclosure : intermediate document #5 F5 I'll-I Relevant CLASSlI"ICA'I'ION OF THE to claim APPLICATION (Int. Cl.5 ) 1-5 C07C255/23 C[]9J4/U4 1-5 TECIINICAL FIELDS SEARCHED (Int. Cl.5 ) C07C Exams WRIGHT M, H,