Primer Composition Containing an Organometallic Compound for Binding substrates with a Cyanoacrylate Adhesive

||||||llllllll||||||||llllllllllllllllllllllllllllll||l||ll|ll|l|l|||I|l||| . _ USO05ll0392A Umted States Patent [191 [11] Patent Number: 5,110,392 Ito et al. [45] Date of Patent: May 5, 1992 [54] PRIMER COMPOSITION CONTAINING AN [58] Field of Search ........................... .. 156/314, 331.2; ORGANOMETALLIC COMPOUND FOR 427/412.1, 412.3, 412.4, 412.5; 106/287.17, BINDING SUBSTRATES WITH A 287.23 . CY ANOCRYLATE ADHESIVE [56] References Cited [75] Inventors: Kenji Ito; Kaoru Kimura, both of U-5- PATENT DOCUMENTS Nagoya, Japan 4,818,325 4/1989 Hiraiwa et al. ................ .. 156/331.2 [73] Assignee: Toagosei Chemical Industry Co., Ltd., Tokyo, Japan [2]] Appl. No.: _518,657 [22] Filed: May 3, 1990 Related U.S. Application Data [63] Continuation-in-part of Ser. No. 219,815, Jul. 14, 1988, abandoned, which is a continuation of Ser. No. 899,800. Aug. 25, 1986, abandoned, which is a continu- ation of Ser. No. 611,691, May 18, 1984, abandoned. [30] Foreign Application Priority Data May 20, 1983 [JP] Japan ................................ .. 58-87761 Dec. 5, 1983 [JP] Japan 58-228323 Mar. 29, 1984 [JP] Japan ................................ .. 59-59367 [51] Int. Cl.5 ..... .._. ...................................... .. C09J 5/04 [52] U.S. Cl. ............................. .. 156/314; 106/287.17; 106/287.23; 156/33l.2;.427/412.1; 427/412.3; 427/412.4; 427/412.5 OTHER PUBLICATIONS Condensed Chemical Dictionary, p. 822, ©1977, 9th Edition. Primary Examiner——JOhn J. Gallagher Attorney, Agent, or J’irm—Cooper & Dunham [57] [ABSTRACT A process for bonding a polyolefinxpolyfluoroolefin, polyethylene terephthalate, polyacetal, nylon or plasti- cizer-rich soft polyvinyl chloride substrate to a like substrate or for bonding a polyolefin, polyfluoroolefin, polyethylene terephthalate, polyacetal, nylon or plasti- cizer-rich soft polyvinyl chloride substrates to another substrate which comprises applying to the surface of at least one of the substrates to be bonded together an adhesion promoter composition comprising 0.00l—1O wt. % of at least one organometallic compound contain- ing a metal selected from the group consisting of typical metals, applying a cyanoacrylate-based adhesive com- prising an alpha-cyanoacrylate and bringing together the thus-treated surface of the substrates to be bonded. 12 Claims, No'Drawings 5,110,392 1 PRIMER COMPOSITION CONTAINING "AN ORGANOMETALLIC COMPOUND FOR BINDING SUBSTRATES WITH A CYANOCRYLATE ADHESIVE This application is a continuation-in-part of applica- tion Ser. No. 219,815 filed Jul. 14, 1988, now abandoned which, in turn, is a continuation of application Ser. No. 899,800 filed Aug. 25, 1986, now abandoned, which, in turn, is a continuation of application Ser. No. 611,691 filed May 18, 1984, now abandoned. This invention relates to a primer which is used as such in bonding non-polar or highly crystalline resin substrates together or bonding other material thereto with use of an a-cyanoacrylate. (This invention has as its object to provide a primer satisfactorily useful in bonding together non-polar or highly crystalline resin substrates together or bonding another material to the resin substrate with use of an a-cyanoacrylate, the resin substrates having herefore been considered as difficult to bond together, bond the other material thereto, coat, paint and print thereon and being typified by polyethylene, polypropylene, polybu- tene, polyfluoroethylene, their copolymer and other polyolefin substrates as well as polyethylene terephthal- ate, polyacetal, nylon and soft PVC film (having a high content of a plasticizer) substrates.) _ To render these substrates or materials improved in adhesiveness, there has heretofore been proposed a surface treating method which comprises subjecting the substrates, for example polyethylene or polypropylene, to flame treatment, corona discharge treatment, irradia- tion treatment or oxidizing treatment with a bichro- mate, sulfate or the like so as to produce polar groups such as a carbonyl group on the surface of the sub- strates. In addition, to make a resin, such as polyfiuoro- ethylene, which is impossible to oxidize on the surface, improved in adhesiveness, there has been proposed a special chemical treatment such as lithium vapor treat- ment, heating treatment with an alkali in a helium stream or treatment of metallic sodium with liquid am- monia. However, the proposed methods and treatments need. special equipments, are complicated to carry out, are unable to uniformly treat every part of the surface of a substrate having a complicated shape and require great expenses, these being disadvantageous. Various primers also have been proposed. For exam- ple, Japanese Patent Appln. Laid-Open Gazettes Nos. 52-98062, 56-141328 and 57-119929 have proposed primers prepared by dissolving a chlorinated polyethyl- ene or chlorinated polypropylene or a fatty acid modi- fied acrylated alkyd resin in an organic acid. According to Japanese Pat. Appln. Laid-Open Ga- zette No. 58-8734, however, the primers so proposed are unsatisfactory in adhesiveness to a paint although they are satisfactory in adhesiveness to a polyolefin substrate, or, even if the paint and the polyolefin are satisfactory in adhesion to each other, the adhesiveness therebetween will undesirably decrease due to repeti- tion of the cold/hot cycle. Japanese Pat. Appln. Laid-Open Gazettes Nos. S4-124048, 54-124049 and 54-124095 have proposed a modified polyolefin prepared by incorporating solid rubber, an unsaturated carboxylic acid or the derivative thereof, and a radical generator in a polyolefin, how- ever, according to Japanese Pat. Appln. Laid-Open 10 15 20 25 30 35 40 45 50 55 65 2 Gazette No. 57-38827, the modified polyolefin will have undesirable effects on the adhesiveness of a paint formed thereon since the unreacted unsaturated carbox- ylic acid and the radical generator remain in the modi- fied polyolefin. Further, Japanese Pat. Appln. Laid-Open Gazettes Nos. 54-124050, 55-34270 and 55-84271 have proposed -an improved resin composed essentially of a propyle- ne/styrene/butadiene block copolymer and an inor- ganic filler, however, the improved resin so proposed seems to raise various problems as to poor weather- proofness of unpainted parts and low-temperature fra- gility due to the incorporation of the filler. (If non-polar or highly crystalline resins such as poly- olefin can be improved in adhesiveness or they can allow a coating, painting or print to be satisfactorily formed on the surface thereof,) they would be very conductive to various fields such as the automobile industry and electric appliance industry since they have many merits such as excellent properties, light weight, rust-proof and low cost as compared with metallic ma- terial. ‘ In attempts to develop a surface treating method which is simple and speedy as compared with the con- ventional methods, in view of the abovementioned situ- ations, the present inventors made intensive studies and, as the result of their studies, they developed desired primers which enable satisfactory adhesion, coating, painting and printing. This invention is based on this development or finding. This invention relates to a primer comprising at least one organometallic compound, which is used in bond- ing non-polar or highly crystalline resin substrates to- gether or bonding another material to the resin substrate with the use of an a-cyanoacrylate. The expression “bonding another material to the resin substrate with the use of an a-cyanoacrylate” used herein is intended to mean, for example, the use of an a-cyanoacrylate in adhesion of a solid material such as a metal, glass, a synthetic resin, rubber, leather, stone, cloth, paper, wood or ceramics to the resin substrate (or the use thereof in coating or printing a resin substrate with a coating material, paint or printing ink.) The primer of this invention is composed of one or more organometallic compounds in which the organic group is combined with a metal. Such organometallic compounds may be used in this invention irrespective of the kind, structure and the like thereof. The organic groups contained in the organometallic compounds include alkyl, cycloalkyl, haloalkyl, alke- nyl, cycloalkenyl, alkoxy, cycloalkoxy, aryl, aralkyl, aralkyloxy, acetylacetate, acyloxy and cycloalk- enyloxy, aryloxy group, with C3 or higher hydrocarbon groups being preferred. The metals contained in the organometallic compounds in this invention are in- tended to include typical metals, transition metals and metalloids and further include phosphorus, boron and silicon. The organometallic compounds are illustrated by the following structural formulae. (1) M—O—R (wherein M is an elemental metal and R an organic group; these definitions apply to the fol- lowing) which shows metal alcoholates: organoaluminum compounds such as aluminum iso- propylate, aluminum mono-sec. -butoxydiisopropylate, aluminum ethylacetoacetate diisopropylate, aluminum oleylacetoacetate diisopropylate; organotitanium com- pounds such as tetrabutyl titanate and tetraisopropyl titanate; organoboron compounds such as tri-n-butyl 3 borate, triphenyl borate, tri-n-octadecyl borate and monobutyldimethyl borate; phosphoric acid esters such as trioleyl phosphate, tridecyl phosphate, dibutyl phos- phite, trisisodecyl phosphite, di-2-ethylhexyl phosphite and tridecyl phosphite; tetraoctyl silicate; triisobutox- ygallium; and tetrabutyl zirconate. (2) / ()= \ M C \ // 0-C \ which shows 1,3-dicarbonyl complexes: complex salts of acetylacetonate such as aluminum trisacetylacetonate, aluminum monoacetylacetonate bisethylacetoacetate, aluminum trisethylacetoacetate; acetylacetone lithium, acetylacetone beryllium, acetyl- acetone sodium, acetylacetone magnesium, acetylace- tone calcium, acetylacetone titanium, acetylacetone strontium, acetylacetone barium, acetylacetone thal- lium, acetylacetone vanadium, acetylacetone manga- nese (IlI), acetylacetone iron (III), acetylacetone tho- rium, acetylacetone chromium (III), acetylacetone rho- dium, acetylacetone cobalt (II), acetylacetone cobalt (III), acetylacetone nickel, acetylacetone copper, ace- tylacetone zinc, acetylacetone zirconium, acetylacetone ‘ palladium, acetylacetone indium, acetylacetone tin (IV) and acetylacetone molybdenum; complex salt of aceto- acetic acid ester, trifluoroacetylacetone and benzoy- lacetone. M—O—C—R (3) ll 0 which shows carboxylates: magnesium stearate, aluminum stearate, calcium stea- rate, ferric stearate, zinc stearate, barium stearate, lead stearate, potassium stearate, copper stearate, manganese stearate, nickel stearate, nickel naphthenate, cobalt naphthenate, manganese naphthenate, magnesium naph- thenate, zinc naphthenate, magnesium palmitate, cad- mium palmitate, cobalt _ palmitate, sodium linoleate, sodium laurate, barium oleate, aluminum laurate, alumi- num oleate, potassium oleate, aluminum acetate, stan- nous acetate, stannous 2—ethylhexanoate, aluminum formoacetate, zinc tartrate and basic aluminum thiodi- glycolate. (4) M—R which shows hydrocarbon group-contain- ing metals: alkyl metals such as zinc 2-ethylhexyl, lithium hexa- decyl, sodium n-hexyl, potassium hexadecyl, aluminum n-trioctyl, lead n-propylethyl, antimony tri-n-pentyl, antimony tri-n-decyl and zinc isobutylisoamyl; organo- tin compounds such as dibutyl tin diacetate, di-n-butyl tin dimaleate, di-n-butyl tin dioxide, triphenyl tin ace- tate, tri-n-butyl tin oxide, dioctyl tin dilaurate, tributyl tin acetate, tributyl tin chloride, tin tetraamyl and dial- lyl tin dichloride; methylvinyldichlorosilane; AY43-021 (tradename of Toray Silicon Co., Ltd.); ferrocene; titanocene dichloride; and nickelocene. (5) M—X—R wherein X is a hetero atom such as the organometallic compounds, for example, metal thioalcoholates such as n-dodecylmercap- topotassium salt and aluminum trithiobutoxide; thi- odicarboxylates such as tin 2-ethylhexanemonothioate 5,110,392 10 15 20 25 30 35 45 50 55 65 4 and zinc 2-ethylhexanedithioate; dithiocarbamates such as nickel dimethyldithiocarbamate, copper dimethyldi- thiocarbamate, iron dimethyldithiocarbamate and zinc diethyldithiocarbamate; sulfonic acids such as nickel benzenesulfonate; phosphates such as vanadium dibu- tylphosphate; and zinc mercaptobenzothiazole. Among these organometallic compounds, the carbox- ylates (3) and the hydrocarbon group-containing metals (4) are preferred, and the metal alcoholates (l) and the 1,3-dicarbonyl complex salts (2) are more preferred. More particularly, the preferred organometallic com- pounds include acetylacetone lithium, acetylacetone sodium, acetylacetone magnesium, acetylacetone tita- nium, acetylacetone iron (III), acetylacetone palladium, acetylacetone indium, tri-n-octadecyl borate, sodium linoleate, magnesium stearate, aluminum stearate, alu- minum acetate, aluminum laurate, basic aluminum thi- odiglycolate, calcium stearate, ferric stearate, ferro- cene, copper dimethyldithiocarbamate, zinc stearate, zinc 2-ethylhexyl, zinc tartrate, stannous acetate, di-n- butyl tin maleate, di-n-butyl tin oxide, triphenyl tin acetate, barium stearate,‘ lead stearate, dibutyl phos- phite, tridecyl phosphate and trioleyl phosphate. The more preferred organometallic compounds include ace- tylacetone calcium, acetylacetone zinc, potassium ole- ate, nickel naphthenate and dioctyl tin dilaurate. The most preferred organometallic compounds include alu- minum isopropylate, aluminum mono-sec. -butoxydiiso- propylate, aluminum ethylacetoacetate diisopropylate, aluminum oleylacetoacetate diisopropylate, aluminum 'trisacetylaceton'ate, aluminum monoacetylacetonate bisethylacetoacetate, aluminum trisethylacetoacetate, acetylacetone manganese (III), acetylacetone cobalt (II), acetylacetone nickel, acetylacetone zinc, acetylac- etone zirconium, tetrabutyl titanate, tetraisopropyl tita- nate, dibutyl "tin diacetate, tri-1'1-butyl tin oxide, tin 2- ' ethylhexanoate, AY43-021 (tradename of a certain sili- con compound produced by Toray Silicon Co., Ltd.) and trisisodecyl phosphite. The primer composed of the organometallic com- pound or compounds according to this invention is used for coating on a non-polar or highly crystalline resin substrates in bonding the resin substrates together or bonding another material thereto with use of ci-cyanoa- crylate. In this case, it is desired to control the thickness of the organometallic compounds coated so that the full effects of this invention are attained as described later. (For this purpose, it is preferred that the compounds be used in solution.) The solvents used herein are preferably capable of completely dissolving or dispersing the organometallic compound therein, has suitable volatility and is industri- ally easily available. The solvents are also preferably such that a resin, such as polyolefm, can be fully wetted on the surface therewith, in order to allow the primers to exercise their performance more efficiently. For this purpose, it is further preferable to selectively use an organic solvent which has a surface tension lower than the critical surface tension 7c of the resin. The follow- ing Table indicates the surface tension and the critical surface tension of typical solvents to help one skilled in the art in selecting a solvent to be used. 5,110,392 5 TABLE Critical surface tension Surface tension of ‘ye of resin organic solvent (dyne/cm. 20° C.) (dyne/cm. 20° C.) Polytrifluoroethylene 22 l,l.2-trichloro-l,1,2- 19 trifluoroethane polyethylene 31 Ethanol 22 Polypropylene 31 Acetone 23 Polyacetal 40 Ethyl acetate 24 Polyvinylidene chloride 40 1,l.l-trichloroethane 26 Polyethylene terephthalate 43 Tetrahydrofuran 26 6-6 nylon 46 1,4-dioxane 27 Toluene 28 It is preferable that a solution of the organometallic compound in a solvent be in a concentration by weight of 0.001—l0% for the reason that the organometallic compound may be coated to nearly thickness of mono- molecular layer thereof whereby the compound can exhibit its best performance as described later. The a-cyanoacrylate used in this invention is repre- sented by the following general formula CN / CH2=C COOR wherein R is alkyl, alkenyl, cycloalkyl, aryl, alkoxya1- kyl, aralkyl, haloalkyl or the like and more particularly it is illustrated by methyl, ethyl, n-propyl, n-butyl, iso- butyl, n-pentyl, ally], cyclohexyl, benzyl or methoxy- propyl. The a-cyanoacrylates used herein are the main com- ponent of commercially available cyanoacrylate-based instant adhesives which may be used as they are, as a-cyanoacrylate in this invention. The commercially available cyanoacrylate-based adhesives are composed mainly of a-cyanoacrylate and may be further incorporated with various ingredients as illustrated below: ‘ (1) Stabilizer (2) Thickener (3) Modifier (4) Dyestuff The stabilizer is for enhancing the storage stability of the cyanoacrylate-based adhesives and is illustrated by sulfur dioxide, an aromatic sulfonic acid or a sultone as an anion polymerization inhibitor and by hydroquinone or hydroquinone monomethyl ether as a radical poly- merization inhibitor. The thickener used herein is for increasing the viscos- ity of the cyanoacrylate-based adhesives to several ten to several thousand cp since usually a-cyanoacrylate is a low viscous liquid having a viscosity of about several op. The thickener used herein includes a polymethyl- methacrylate, acryl rubber or cellulose derivative. The modifier used herein is for improving the impact resistance or heat resistance which are drawbacks of conventional cyanoacrylate-based adhesives and is illus- trated by maleic anhydride or a derivative thereof as an improver of heat resistance as indicated in Japanese Pat. Appln. Gazette No. 52-12737. To enable a porous and acidic sap-containing woody material which has hereto- fore been considered difficult to bond, to be bonded, crown compounds and the like may be used as indicated in,’ for example, Japanese Pat. Appln. Publication Ga- zette No. 55-2238. 5 IO 20 25 30 35 45 50 55 60 65 6 Further, to provide a flexible adhesive layer, the original adhesive may be incorporated with a plasticizer such as tricresyl phosphate, dioctyl phthalate or di- methyl sebacate. The dyestuff used herein is for, for example, render- ing a bonded portion easily identifiable, the original adhesive may be incorporated with, for instance, an acidic salt of basic dye as indicated in Japanese Pat. . Appln. Laid-Open Gazette No. 53-37260 or the like. Furthermore, the original adhesive may further be incorporated with a perfume such as an ester derivative as indicated in Pat. Appln. Laid-Open Gazette No. 53-58541 or the like, in order to provide the adhesive with fragrance. In the practice of this invention, the a-cyanoacrylate may be used in the form of a diluted solution in a spe- cific organic solvent. The organic solvent should be such that it is compatible with the a-cyanoacrylate and does not impair the stability thereof, and it includes toluene, butyl acetate or methylchloroform. It is pre- ferred that the organic solvent contains none of mois- ture and other impurities. In a case where two substrates to be bonded together are each a non-polar or highly crystalline resin, coating of the organometallic compound may be effected by immersing both of the substrates in a solution of the primer for several seconds”or coating it with the solu- tion by the use of a brush or spray gun and then air drying, while in a case where only one of the substrates to be bonded together is a non-polar or highly crystal- line resin, that substrate may be treated in the same manner as above. The primer coated non-polar or highly crystalline resin substrates are bonded together or with another material using the a-cyanoacrylate to obtain a bonded body having very excellent bond strength. In the coating method of the primer, there may also be used a method which comprises coating a mixture of the a-cyanoacrylate and the organometallic compound ‘ on a substrate with or without using organic solvent, or a method which comprises ejecting an a.-cyanoacrylate and a solution of the organometallic compound simulta- neously by the use of spray gun having two nozzles. In the former method, full care must be taken to prevent moisture, amines, alcohols and other foreign matters from mixing in the mixture since the a-cyanoacrylate specifically has a strong anionic activity. In a process for forming a coating, painting or print- ing on a non-polar or highly crystalline resin substrate, the primer is coated on the resin substrate by the above- mentioned coating method, and then an a-cyanoacry- "late is coated and polymerized to form a polymer film thereof, thus producing a resin substrate having satisfac- tory receptivity and bond strength to coating materials, paints and printing‘ ink. The thus produced resin sub- strates may be coated or printed by a conventional means to form an excellent coating, painting and print- ing thereon. ' In the coating steps the following steps will show more excellent effects in coatings. In a first step, a primer prepared by dissolving the organometallic compound in an organic solvent to pro- duce a primer composition comprising or consisting essentially of the organometallic compound in the or- ganic solvent. The primer composition is coated on a substrate on which a coating, painting or printing is to be formed by an immersing or spraying method and 5,110,392 7 being laid usually 5-60 minutes at room temperature or several days depending on the operational steps taken. In a second step, the a-cyanoacrylate is coated on the primer-coated substrate to form a poly-a-cyanoacrylate film, by a coating method using a preliminarily acid- treated brush, an immersing method, a spraying method, or the like. In a case where the spraying method is used, it is preferred to use a diluted solution of on-cyanoacrylate in an organic solvent in order to pre- vent the nozzles of spray gun from being clogged. In addition, in a case where a commercially available cyanoacrylate-based adhesive is used, it is preferable to choose the low viscosity one. The substrate on which the a-cyanoacrylate has been coated is allowed to stand at room temperature for at least 12 hours to form a poly-a-cyanoacrylate film. The poly-a-cyanoacrylate film is not particularly limited in thickness, but it is preferable that the thick- ness be in the range of 0.l—100p., preferably l0—50p. to eliminate defective coated portions. The substrate on which the primer and a-cyanoacry- late have been coated as indicated above, is then coated with a usual coating material, painted with a paint or printed with a usual printing ink. There are various kinds of coating materials, paints or printing inks which may be classified in various ways, however, they may be enumerated from the view-point of the kind of vehicle resin used, as follows: rosin derivatives, nitrocellulose resins, vinylic resins, acrylic resins, polyester resins, polyamide resins, poly- urethane resins, phenolic resins, epoxy resins, ami- noalkyd resins, melamine resins and UV-curable acryl oligomers. From the View-point of use, particularly preferred coating materials, paints or printing inks for use in ap- plying to a polyolefin substrate are those containing a polyurethane resin, an epoxy resin, or an alkyd resin. As to thermosetting coating materials, those which may be cured at a baking temperature of not higher than 90° C. are preferred. ' A coating material or a paint may be applied by a usual method such as a coating method using a brush, a bar coater, a roller coater or a spray gun, while a print- ing ink may be applied by a usual method such as a silk screen printing method, a gravure printing method or a flexographic printing method. It is not clear why the adhesiveness of a non-polar or highly crystalline resin to another material is improved by using the organometallic compound of this invention as the primer and the a-cyanoacrylate, however, the organometallic compounds will exhibit their best primer performance when they are very thinly coated to an extent that the amount thereof coated reaches 0.001 to 1 g/m2 although the optimum thickness varies 10 15 20 25 30 35 45 50 55 depending on the kind of the organometallic compound ' used. Bonding tests were made by using a polypropylene plate (2 mm thick) as the resin substrate, acetylacetone zirconium (used as solutions of various concentrations in methylchloroform) as the primer, and an a-cyanoa- crylate-based adhesive (produced under the tradename of Aron Alpha No. 201 by Toagosei Chemical Industry Co., Ltd.), to obtain bonded products which were mea- sured for tensile shear strength at the bonded portion. The following Table A indicates the differences in ten- sile shear strength due to the differences in amount of the primer coated. The bonded products were aged at 65 8 23° C. under a relative humidity (RH) of 60% for one day. TABLE A Amount of Tensile shear Cone. of primer primer coated strength (wt. %) (g/m2) (Kgf/cmz) 5 ’ 0.5-2.5 » 3 3 0.3-1.5 10 l ’ 0.1-0.5 15 0.5 0.05-0.25 36 0.25 0.025—0.l25 . 55‘ 0.05 0.005—0.025 60‘ 0.025 0.0025—0.0125 27 0.01 0001-0005 11 0.001 0.000l—0.0005 3 Note: The symbol “"‘ indicates the destruction of plate. It is seen from the results in Table A that the primer will exhibit its best performance when it is coated in nearly the thickness of its monomolecular layer. From the above results and the fact that the organometallic compounds have a polar segment and non-polar seg- ment in structure, it is surmised that the effects of this invention are produced under the following mecha- nism. The organometallic compound, that is, the primer of this invention is present in approximately the monomo- lecular layer between the surface of the non-polar or highly crystalline resin substrate and the a-cyanoacry- late layer (monomer or polymer film layer) whereby the groups highly compatible with the resin layer and the groups highly compatible with the a-cyanoacrylate layer, in other words, the lipophilic groups and the polar groups are arranged in order and these groups act as a bonding agent to obtain the effects of this invention. To obtain the best results in accordance with this invention, it is necessary to determine an organometal- lic compound to be used, the concentration of the com- pound, the amount thereof applied, and the like in view of the nature of the organometallic compound, a sub- strate and a material to be bonded thereto. As to the amount of the organometallic compound (primer) ap- plied, the use of the primer in such a small amount that the resulting primer layer does not cover all the surface of the substrate which is needed, will naturally not give good results, whereas the use thereof in such a large amount that the resulting primer layer is thicker than the monomolecular layer, will result in forming a fragile primer layer whereby the results of this invention are not obtained. Thus, the concentration of solution of an organometallic compound (primer solution) is prefera- bly 0.001—10% by weight and the amount of the primer coated is in the range of preferably 0.001-1 g/m2, more preferably 0.01-0.1 g/m2. A secure bond is effected between a non-polar or highly crystalline resin substrate and an a-cyanoacry- late with aid of the organometallic compound present therebetween whereby the resin substrate is much im- proved in adhesiveness and, further, a usual coating material or printing ink can easily be applied to the treated resin substrate without causing any problems owing to the presence of a poly-a-cyanoacrylate film formed thereon. The excellent effects obtained by the practice of this invention are those which may be attained by the com- bined use of the a-cyanoacrylate, organometallic com- pound and non-polar or highly crystalline resin sub- strate. On the other hand, in cases where a bond is 5,110,392 9 10 attempted to be effected between polyolefin (such as -1-ABLE Lcominued polyethylene) and something, an organotitanium com- _ pound was once studied to find whether it is useful as a primer or preliminary treatment; in these cases, how- ever, excellent effects were not appreciated since an 5 Primer used Run ?£"—'—"'MaX Min Ave epoxy, urethane, rubber or acrylic adhesive was used. ,_ These conventional means do not anticipate at all the 1 b“‘°""d“S°p'°pyl""e g 32 1': present invention which will unexpectedly excellent A] monoacetylacmnate 1 ‘:9. 0:9 1:5 effects when practiced. diethylacetoacetate 2 1.7‘ 0.6 1.3 The effects of this invention will be exhibited only 10 , 2 1~7‘ 0-3 1-2 when a non-polar or highly crystalline resin is used as A1 ‘"‘°‘hy1‘’°°‘°a°°"“° ; 3'3 the substrate, whereas they will not be exhibited when 3 1:3. 0:7 1:2 other materials (such as a metal, wood or porcelain) are Com. No primer used 1 0 used as the substrate. Example 2 0 The primer of this invention is effective for a non- 15 I 3 0 polar or highly crystalline resin such as polyethylene ,’l“.:“‘ ho] d. h d . m terephthalate, polyacetal or nylon and is particularly esym m mm 5 emmono ‘ms’ effective for polyolefin such as polyethylene and poly- _ propylene. « EXAMPLE 2 AND COMPARATIVE EXAMPLE 2 1o$i1:;1er;;:‘It)‘l°eIs'Xlglgfmtggfiiigggigfilcggsky the fol" 20 One gram of each of aluminum isoProPV1ate and aluminum ethylacetoacetate dusopropylate were dis- EXAMPLE 1 AND COMPARATIVE EXAMPLE 1 solved in 99 g of toluene to prepare a primer solution; ‘ Two pieces, 12.7 mm square>< 38 mm, of each of polyethylene, polypropylene and polyacetal were ground with a smooth-cut plain file to obtain pieces 0.3 g of each of aluminum mono-sec. butoxydiisopro- pylate, aluminum monoacetylacetonate diethylacet- 25 oalcetgt‘? 333 ';11umiIfm11T 1trtiS?t:1y1a°et£aCetate were dis' having a smooth ground face. The thus obtained pieces s°.Ve m] t.’ g 0 ’ ’ ' “C omet me to prepare a were brushed with the primer solution and air dried for pnmer 5° “ lon‘ about 10 minutes. In each of the polymers coated with Two pieces, 25Xl0OX0.2 mmt, of a polyethylene different - - - . primers, the two primer coated pieces were mm were each ijrushed 09 one fac‘? wlih each of the 30 bonded together with Aron Alpha No. 201 (cyanoacry- thus prepared primer solutions and air dried for about 5 lawbased adhesive produced by Toagosei Chemical minutes. Thus the primer coated film pieces were Industry Co.’ Ltd), and were then aged under a com_ bonded together about one half (5) of its length with - 2 Aron Alpha No. 221 (Trade name, cyanoacrylate-based Egisrsgve load of 0'1 Kgf/cm at room temperature for 24 adhesive produced by Toagosei Chemical Industry Co., 35 The thus obtained test pieces were measured for ten_ L _ , ]-1 ' . . . otldfi :1.’/‘Smv;’:l;e1_go::Zfifid61:23:;i.::;p1::)::f01::‘Ea?If sile bond strength at a pull rate of 20 mm/min. using a a'teSIgpieCe p Strograph W-type tester in accordance with I IS K6861- ‘ . . 1977. peghsotfizt spt1ree‘:gSt}sl°a(t)bataI1)':$iinzegtfaggl$8a:::;1mfi:r 40 For comparison, the above procedure was followed using a Strograph W-type tester in accordance with J IS ::f;1:t at the pnmer was no‘ used (comparatwe Ex- K6854'1977 (Example 1)‘ The results are as shown in Table 2. TABLE 2. ’ Bond Between Polyethylene Substrates, Polypropylene Substrates Or Polyacetal Substrates Tensile strength §Kgf/cmzl Polyethylene/ Polypropylene/ Polyacetal/ Primer used Run polyethylene polypropylene polyacetal Example 2 Al isopropylate l 45 43 134 2 38 47 Ill 3 41 ' 39 130 Al ethylacetoacetate 1 56 47 127 diisopropylate 2 43 51 141 ’ 3 48 55 133 Comparative No primer used 1 13 16 90 Example 2 ' 2 16 ll 71 3 10 13 83 For comparison, the above procedure was followed except that the primer ‘was not used (Comparative Ex- ample 1). The results are as shown in Table 1. 60 EXAMPLE 3 AND COMPARATIVE EXAMPLE 3 0.5 g of each of aluminum oleylacetoacetate diisopro- TABLE 1 pylate, aluminum isopropylate and aluminum ethylacet- Bond Between polyethylene Films oacetate diisopropylate were dissolved in 99.5 g of Peel strength 65 1,1,2-trichloro-1,2,2-trifluoroethane to prepareta primer _£!{_E£/_Z5_'"_"_1L_ solution. The two film pieces were treated and tested in Prime‘ “Ed R“ Max Min Me the same manner as in Example 1 except using Example Al mono-sec. 1 2.0- 0.7 1.6‘ 25 X l0Ox0.1 mmt of a polytrifluoroethylene and Aron 5,110,392 11 Alpha No. 221F (cyanoacrylate-based adhesive pro- duced by Toagosei Chemical Industry Co., Ltd.). For comparison, the above procedure was followed except that the primer was not used (Comparative Ex- ample 3). The results are as shown in Table 3. 5 TABLE 3 Bond Between polytrilluoroethvlene Films ’ Peel strength ggf/25 mm! 10 Primer Run Max Min Ave Example A1 triisopropylate 1 80 20 55 3 2 93 65 80 . 3 91 47 74 Al ethylacetoacetate l 145 60 113 diisopropylate 2 120 17 110 15 3 119 . 52 105 A1 oleylacetoacetate 1 125 105 115 diisopropylate 2 ‘90 30 65 - 3 107 88 72 Com. No primer used 1 0 Example 2 0 20 3 3 0 EXAMPLE 4 AND COMPARATIVE EXAMPLE 4 0.5 g of aluminum oleylacetoacetate diisopropylate 25 was dissolved in 99.5 g of each of ethanol, ethyl acetate and tetrahydrofuran to prepare primer solutions. Thereafter, the two film pieces were treated and tested in the same manner as in Example 1 except using 25 X l0OXO.5 mmt of a PVC film and Aron Alpha No. 30 201. For "comparison, the above procedure was followed except that a primer was not used (Comparative Exam- ple 4). The results are as indicated in Table 4. 35 TABLE 4 Bond Between Transparent Soft PVC Films Peel strength (Kgf/25 mm) Solvent used n Max Min Ave 40 Example 4 Ethanol 1 10.0 2.2 6.7 2 8.4 1.9 5.9 3 9.2 1.8 6.3 Ethyl acetate 1 9.6 2.3 7.3 2 7.7 1.5 - 6.6 3 7.1 1.8 6.1 45 Tetrahydrofuran l 8.2 2.4 7.0 2 6.7 1.2 5.8 3 9.3 1.9 6.5 Com. No primer used 1 0.4 0.2 0.3 Example 4 2 0.3 0.1 0.2 3 0.3 0.1 0.2 so EXAMPLE 5 AND COMPARATIVE EXAMPLE 5 The primers, polyolefin substrates and a-cyanoacry- late used were as follows: 55 1. primers (1) Acetylacetone zirconium (2) Acetylacetone manganese (III) (3) Acetylacetone nickel 0.2 g of each of the above compounds, that is primers, 60 were dissolved in 99.8 g of toluene to prepare a primer solution. 2. Substrates to be bonded (1) Polyethylene plate (25)< lOOX2 mm) (2) Polypropylene plate (25 X 100x 2 mm) (3) Polybutene plate (25X l00>