DIGUANAMINE, AND PRODUCTION, DERIVATIVE AND USE THEREOF

Abstract: A diguanamine represented by general formula (1); a process for producing the same by the reaction of a dicarbonitrile represented by the general formula: NC-R-CN with dicyandiamide in the presence of a basic catalyst; and a thermosetting composition comprising, for example, a coating resin containing methylolated diguanamine, etherified diguanamine, precondensates thereof and derivatives thereof, and a thermosetting resin composition comprising, for example, a coating resin or an adhesive resin containing the diguanamine and an epoxy resin. In said formulae, R represents bicyclo[2.2.1]-2,5-heptylene, bicyclo[2.2.1]-2,6-heptylene or cyclohexylene.

Description: TECHNICAL FIELD This invention relates to novel diguanamines, which are useful as polymerizable monomers, as resin raw materials for paint resins, adhesive resins, paper coating resins, fiber treatment resins, powder coating resins and building materials, as raw materials for guanamine compound derivatives, as curing agents for epoxy resins and urethane resins, and as modifiers for high molecular substances such as rubber materials. The present invention is also concerned with a preparation process of the diguanamines, their derivatives useful as curing agents and intermediates for various resins, and also with use of the diguanamines and the derivatives thereof. BACKGROUND ART As resin raw materials for paint resins, adhesive resins, paper coating resins, fiber treatment resins and hide treatments, curing agents for various resins, modifiers for rubber materials, modifiers for organic materials, and the like, guanamines containing an aminotriazine group, such as melamine and benzoguanamine, have heretofore been used widely for their excellent properties including the high hardness and gloss, colorless clearness, great chemical resistance and waterproofness and excellent abrasion resistance and electrical properties and, as curing agents, for the superb pot life of the resulting resins. Further, a variety of research and development work has been conducted on such melamines and guanamines containing an aminotriazine group, resulting in the provision of even polyfunctional guanamines which contain a tetrafunctional group or a still higher functional group and show excellent characteristic properties from the viewpoint of the flexibility, toughness, high hardness, waterproofness, curability and the like of resins. Such polyfunctional guanamines are absolutely different in structure from the novel diguanamines according to the present invention, so that it is extremely difficult to make a comparison therebetween. For the sake of reference, however, examples which may be given boldly include phthaloguanamine represented by: and spiroguanamine represented by: The former compound is, however, accompanied by drawbacks such that resins obtained using it as a raw material are very poor in ultraviolet light resistance and weatherability and cannot hence be used at all as resin raw materials for exterior paints, weatherproof paints, automotive paints and building resins or are subjected to a considerable limitation upon such applications and that a substantial limitation is also imposed on its use as a raw material for water-base paint resins because the water reducibility of amino resins formed of phthaloguanamines as its derivatives is still insufficient in practice although it has been improved somewhat over conventional melamine-base amino resins. The latter compound, on the hand, is also accompanied by drawbacks such that resins obtained using it as a raw material have poor inferior heat resistance and poor wheatherability, ultraviolet light resistance and waterproofness and are difficult to retain their expected functions outdoors over a long time as resins for exterior paints, weatherproof paints, automotive paints and building materials. Further, because of the low activity of the amino groups in the latter compound as typified, for example, by the low reaction velocity of the reaction of the latter compound for the formation of a methylol derivative, the latter compound also involves such a problem that a substantial limitation is imposed on the production of various useful guanamine derivatives, resins and resin curing agents available by reactions of the amino groups and also on the production of formaldehyde co-condensation polymers between the latter compound and compounds such as melamine and benzoguanamine. Moreover, a reaction mixture obtained by the formation of a methylol derivative of the latter compound can hardly be obtained as a clear solution, leading to a further drawback such that when employed as a raw material for water-base resins, for example, water-base paint resins, adhesive resins, paper coating resins and fiber treatment resins, sufficient properties can hardly be obtained in the smoothness, curability and physical properties of the resulting coating films and the reaction mixture cannot be used for such applications or is subjected to a considerable limitation in such applications. The latter compound is accompanied by a still further drawback such that production of spironitrile as a starting material for the preparation of the latter compound involves not only technical problems such as the need for many complex steps including a cumbersome purification step but also a substantial impairment in economy. As has been described above, these compounds have been subjected to significant technical and economical limitations upon their use and preparation. In addition to the guanamine compounds represented by the formulae given above, further compounds containing diamino triazinyl groups have been disclosed in the prior art. US-A-3 408 254 describes 2,2'-(1,2-cyclobutylene)bis[4,6-diamino-s-triazine] as useful for preparing resin compositions. US-A-2 532 519 relates to complex aryl diguanamines which are comprised of diamino triazinyl moieties linked by a divalent aromatic radical. EP-A-0 391 665 relates to amino compounds which consist of substituted diamino triazinyl moieties linked via a -(CH 2 ) 4 - group. EP-A-0 422 402 discloses N,N,N',N'-tetraalkoxymethyl cyclohexanecarboguanamines. US-A-2 901 464 relates to compounds having triazinyl moieties linked via a -CR 1 R 2 -O-R-O-CR 3 R 4 - group, wherein R 1 , R 2 , R 3 and R 4 are hydrogen or lower alkyl and R is an alkylene, alkylidene or alkylidene diphenyl radical. DISCLOSURE OF THE INVENTION With the foregoing drawbacks in view, the present inventors have proceeded with an extensive investigation. As a result, diguanamines totally different in structure and characteristic properties from the multifunctional diguanamines described above for the sake of reference have been found. These diguanamines contain active amino groups which show excellent reactivity to compounds having various functional groups. Owing to the inclusion of eight active hydrogen atoms, the degree of methylol derivation and the like can be selected from a wide range. They are excellent in weatherability, ultraviolet light resistance and the like, so that they can retain their expected functions outdoors or under similar conditions over a long time. Further, their methylol derivatives are excellent in properties such as water dilution, curability, waterproofness, antifouling property, flexibility, hardness and toughness. An excellent process for the preparation of such diguanamines has also been found. According to the process, each target diguanamine compound can be obtained at a high purity with production of byproducts in extremely small amounts and in a high yield from a corresponding dicarbonitrile available at low cost and requires simple preparation steps such as a simple purification and isolation step. These findings have led to the present invention. As derivatives available from such useful diguanamines, the present inventors have also prepared N-methylol derivatives by reacting the diguanamines with aldehydes, etherified diguanamines by etherification of the N-methylol derivatives with alcohols, and their initial condensates. The present inventors have also found curing agents for various resins, thermosetting compositions containing these derivatives useful as raw materials for resins such as paint resins, and thermosetting resin compositions containing the diguanamines and epoxy-containing resins and useful as paint resins, powder coating resins and adhesive resins, leading to the present invention. The diguanamines described above are extremely useful compounds, and can provide polymers, compounds and compositions excellent as rubber modifiers, optical materials, resist materials, electrical insulating materials, automotive paints, paints for home electric and electronic appliances, antifouling paints, weather-proof paints, fluorescent paints, resinous building materials, powder coatings, water-base paints, oil-base paints, paper coating resins, fiber treatment resins, adhesive resins, IC packaging resins, anticorrosion resins, polymer modifiers, hide treatments, plastic magnets, latex antioxidants, electrophotographic photoconductors, surfactants, agricultural chemicals, medicines, etc. The present invention therefore provides: (a) a diguanamine represented by the following formula (1): wherein the bonding sites of the 4,6-diamino-1,3,5-triazin-2-yl groups are the 2,5- or 2,6-positions, or by the following formula (2) wherein the bonding sites of the 4,6-diamino-1,3,5-triazin-2-yl groups are the 1,2-, 1,3- or 1,4-positions; (b) a process for the preparation of a diguanamine, which comprises reacting a dicarbonitrile, which is represented by the following formula (3): wherein the bonding sites of the cyano groups are the 2,5- or 2,6-positions, or by the following formula (4): wherein the bonding sites of the cyano groups are the 1,2-, 1,3- or 1,4-positions, with dicyandiamide in the presence of a basic catalyst; (c) a process for the preparation of a diguanamine, as described above under (b), wherein the basic catalyst is at least one compound selected from the group consisting of alkali metals, alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal alcoholates, alkali metal salts of dicyandiamide, alkaline earth metal salts of dicyandiamide, amines and ammonia; (d) a process for the preparation of a diguanamine, as described above under (b), wherein the reaction is conducted using as a reaction solvent at least one solvent selected from the group consisting of non-aqueous protonic solvents and aprotonic polar solvents; (e) a process for the preparation of a diguanamine, as described above under (b), wherein the reaction is conducted in a temperature range of from 60°C to 200°C; (f) an N-methylol diguanamine obtained by subjecting the diguanamine described above under (a) and an aldehyde to an addition reaction; (g) an etherified diguanamine obtained by subjecting the N-methylol diguanamine derivative as described above under (f) and at least one alcohol selected from alcohols having 1-20 carbon atoms to esterification, said etherified diguanamine containing at least one R 1 OCH 2 group wherein R 1 represents a residual group formed by removing a hydroxyl group form the alcohol; (h) a primary condensate of N-methylol diguanamine obtained by subjecting the diguanamine described above under (a), a condensable compound as an optional reactant, and an aldehyde to addition condensation, having an average addition condensation degree greater than 1 and containing at least one methylol group; (i) a primary condensate of etherified diguanamine obtained by subjecting the diguanamine described above under (a), a condensable compound as an optional reactant and an aldehyde to an addition reaction or addition condensation reaction and then subjecting the reaction product and at least one alcohol selected from alcohols having 1-20 carbon atoms to etherification and optionally to simultaneous condensation, having an average addition condensation degree greater than 1 and containing at least one R 1 OCH 2 group wherein R 1 has the same meaning as defined above); (j) a thermosetting composition comprising, as an essential component, at least one compound selected from the group consisting of the N-methylol diguanamines as described above under (f), the etherified diguanamines as described above under (g), the primary condensates of the N-methylol diguanamines described above under (h), and the primary condensates of the etherified diguanamines described above under (i); (k) a thermosetting composition as described above under (j), further comprising a resin curable through a reaction with the component described above under (j); (ℓ) a paint resin composition comprising the thermosetting composition described above under (k); (m) a thermosetting resin composition comprising the diguanamine as described above under (a) and an epoxy-containing resin; (n) a paint resin composition comprising the thermosetting resin composition described above under (m); (o) a paint resin composition as described above under (n), said composition being a powder coating resin composition; and (p) an adhesive resin composition comprising the thermosetting resin composition as described above under (m). BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an infrared absorption spectrum of a compound obtained in Example 1; FIG. 2 is a mass spectrum of the compound obtained in Example 1; FIG. 3 is an infrared absorption spectrum of a compound obtained in Example 3; and FIG. 4 is a mass spectrum of the compound obtained in Example 3. BEST MODE FOR CARRYING OUT THE INVENTION In the diguanamine (1) according to this invention, the bonding sites of the 4,6-diamino-1,3,5-triazin-2-yl groups are the 2,5- or 2,6-positions. The configuration of such groups is an endo-endo form, end-exo form or exo-exo form. These stereoisomers are all useful compounds. Although the diguanamine (1) is a compound selected from the group consisting of the above-described isomers in bonding sites or configuration, mixtures of different compounds selected from such a group are also extremely useful from the industrial viewpoint like the individual compounds. Specific examples of the diguanamine (1) include, but are not limited to, 2,5-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane (end-exo form), 2,5-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane (exo-exo form), 2,6-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane (endo-endo form), and 2,6-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane (exo-exo form). In the diguanamine (2) according to this invention, the bonding sites of 4,6-diamino-1,3,5-triazin-2-yl groups are the 1,2-, 1,3- or 1,4-positions. The configuration of such groups are either a trans form or a cis form. These stereoisomers are all useful compounds. Although the diguanamine (2) is a compound selected from the group consisting of the above-described isomers in bonding sites or configuration, mixtures of different compounds selected from such a group are also extremely useful from the industrial viewpoint like the individual compounds. Specific examples of the diguanamine (2) include, but are not limited to, 1,2-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane (cis form), 1,2-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane (trans form), 1,3-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane (trans form), 1,3-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane (cis form), 1,4-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane (trans form), and 1,4-bis-(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane (cis form). Each diguanamine according to the present invention can be obtained, for example, by a process in which a dicarbonitrile represented by the following formula (3): wherein the bonding sites of the cyano groups are the 2,5- or 2,6-positions, or by the following formula (4): wherein the bonding sites of the cyano groups are the 1,2-, 1,3- or 1,4-positions is reacted with dicyandiamide in the presence of a basic catalyst or by a process in which an ester of a dicarboxylic acid corresponding to the dicarbonitrile and a biguanide are reacted optionally in the presence of a basic compound. The former process is excellent both technically and economically and is extremely practical, because the raw materials are readily available and are easy to handle, byproducts are minimized and the target compound can be obtained with high purity, preparation including a purification step is simple, the loss of the raw materials is very small, and the target compound can be obtained in a high yield. It is however to be noted that the preparation process of the diguanamine is not necessarily limited to these processes. In the dicarbonitrile (3) in the preparation process of the diguanamine, said process pertaining to this invention, the bonding sites of the cyano groups are the 2,5- or 2,6-positions. The configuration of these groups is an endo-endo form, endo-exo form or exo-exo form. These stereoisomers are all useful. Although the dicarbonitrile (3) is a compound selected from the group consisting of the above-described isomers in bonding sites or configuration, mixtures of different compounds selected from such a group are also useful like the individual compounds. The dicarbonitrile (3) can be obtained, for example, by a process in which bicyclo[2.2.1]hepta-5-ene-2-carbonitrile and a hydrogen cyanide are reacted in the presence of a particular catalyst such as Co 2 (CO) 8 , Fe(CO) 5 or Ni[P(OC 6 H 5 ) 3 ] 4 as disclosed in U.S. Patent No. 2666748 or the like, by a process in which 5-(and/or 6-)cyano-bicyclo[2.2.1]hepta-2-carbaldehyde and a hydroxylamine are reacted as disclosed in U.S. Patent No. 3,143,570 or the like, or by a process in which 2,5- (and/or 2,6-)dichloro-bicyclo[2.2.1]heptane and a cyanating agent such as an alkali metal cyanate or alkaline earth metal cyanate are reacted. It is however to be noted that the preparation process is not limited to such processes. Specific examples of the dicarbonitrile (3) include, but are not limited to, bicyclo[2.2.1]heptane-2,5-dicarbonitrile (endo-exo form), bicyclo[2.2.1]heptane-2,5-dicarbonitrile (endo-endo form), bicyclo[2.2.1]heptane-2,6-dicarbonitrile (endo-exo form), and bicyclo[2.2.1]heptane-2,6-dicarbonitrile (exo-exo form). In the dicarbonitrile (4) in the preparation process of the diguanamine, said process pertaining to this invention, the bonding sites of the cyano groups are the 1,2-, 1,3- or 1,4-positions. The configuration of these groups is either a trans form or a cis form. These stereoisomers are all useful compounds. Although the dicarbonitrile (4) is a compound selected from the group consisting of the above-described isomers in bonding sites or configuration, mixtures of different compounds selected from such a group are also useful like the individual compounds. The dicarbonitrile (4) can be obtained, for example, by a process in which 4-cyanocylohexene and hydrogen cyanide are reacted in the presence of a catalyst such as Ni[P(OC 6 H 5 ) 3 ] 4 as disclosed in U.S. Patent No. 3496217 or the like, by a process in which 3- (and/or 4-)cyano-cyclohexanecarbaldehyde and a hydroxylamine are reacted as disclosed, by a process in which a dihalogenated cyclohexane corresponding to the dicarbonitrile (4) and a cyanating agent such as an alkali metal cyanate or alkaline earth metal cyanate are reacted, by a process in which a dicarboxylic acid corresponding to the dicarbonitrile (4) or the diammonium salt, diamide or diester derivative of the dicarboxylic acid and ammonia are reacted using a dehydrating agent such as alumina catalyst or thionyl chloride, or by a process in which 1-cyanocyclohexene and hydrogen cyanide are reacted in the presence of an alkali such as sodium hydroxide. It is however to be noted that the preparation process is not limited to such processes. Specific examples of the dicarbonitrile (4) include, but are not limited to, 1,2-cyclohexanedicarbonitrile (trans form), 1,3-cyclohexanedicarbonitrile (trans form), 1,3-cyclohexanedicarbonitrile (cis form), 1,4-cyclohexanedicarbonitrile (trans form), and 1,4-cyclohexanedicarbonitrile (cis form). In the process of the present invention for the preparation of the diguanamine, the molar ratio of the dicarbonitrile to dicyandiamide to be reacted with each other can be chosen suitably as needed. The molar ratio of the dicarbonitrile to dicyandiamide to be reacted with each other is 1:2 stoichiometrically. Use of dicyandiamide at an unduly small molar ratio relative to the dicarbonitrile is not preferred because the yield of the diguanamine according to this invention becomes low and, moreover, the corresponding mono-guanamine [1:1 (by molar ratio) reaction product of the dicarbonitrile and dicyandiamide] is formed more and the purification step and the like thus become irksome. Use of dicyandiamide at an unduly large molar ratio makes irksome the removal, separation and the like of unreacted dicyandiamide, etc. Use of dicyandiamide at such an unduly small or large molar ratio is therefore not preferred both technically and economically. With a view toward improving the yield of the diguanamine according to the present invention and also simplifying the process including the purification step, it is generally desired to react 1.5-10.0 moles, preferably 2.0-5.0 moles of dicyandiamide with 1 mole of the dicarbonitrile. Examples of the basic catalyst in the process of the present invention for the preparation of the diguanamine include alkali metals such as potassium and sodium; alkali metal and alkaline earth metal hydroxides such as lithium hydroxide, potassium hydroxide, sodium hydroxide, calcium hydroxide and barium hydroxide; alkali metal and alkaline earth metal carbonates such as potassium carbonate, sodium carbonate and barium carbonate; alkali metal alcoholates such as potassium ethylate, sodium methylate and sodium ethylate; alkali metal and alkaline earth metal salts of dicyandiamide; amines such as 1,8-diazabicyclo[5.4.0]undecene-7, triethylenediamine, piperidine, ethylenediamine, diethylenetriamine, pyrrolidone and tetrahydroquinoline; and ammonia. Particularly preferred are alkali metals, alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal alcoholates, the alkali metal salts of dicyandiamide, the alkaline earth metal salts of dicyandiamide, amines and ammonia. They can be used either singly or in combination. Although no particular limitation is imposed on the amount of such a catalyst, it can be added in an amount of 500-0.001 mole%, preferably 300-0.1 mole% based on the dicarbonitrile from the viewpoint of preparation conditions and economy. The amount of the catalyst can be chosen suitably as needed. In the above process for the preparation of the diguanamine, it is extremely practical to conduct the process while using one of various solvent as a reaction solvent in order to perform the reaction more smoothly. It is however not preferred to use any solvent which may induce the formation of a compound other than the target compound or may cause an inhibition on the reaction, for example, a solvent such as a fatty acid, a fatty acid anhydride, trifluoroacetic acid, liquid sulfur dioxide, sulfuryl chloride, a mineral acid or water. Illustrative of the reaction solvent include alcohols such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, tert-butanol, 2-ethylhexanol, dodecyl alcohol, allyl alcohol, propargyl alcohol, benzyl alcohol, cyclohexanol, ethylene glycol, butanediol, glycerin, 1,2,6-hexanetriol, 2-methoxyethanol, 2-ethoxyethanol, 2-isopropoxyethanol, 2-butoxyethanol, furfuryl alcohol, tetrahydrofurfuryl alcohol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, diacetone alcohol, 2,2,2-trifluoroethanol and 1,3-dichloro-2-propanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and acetophenone; esters such as ethyl acetate, butyl acetate and benzyl acetate; ethers such as diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetrahydrofuran, dioxane, crown ethers and anisol; carboxylic acid amides such as N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and 1,3-dimethyl-2-imidazolidinone; sulfolanes such as sulfolane, methylsulfolane and 1,3-propanesultone; sulfoxides such as dimethyl sulfoxide; amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, isopropylamine, butylamine, 2-ethylhexylamine, allylamine, aniline, cyclohexylamine, pyridine, piperidine, monoethanolamine, 2-(dimethylamino)ethanol, diethanolamine, triethanolamine, isopropanolamine and triisopropanolamine; and ammonia. Particularly preferred are non-aqueous protonic solvents such as alcohols, amines and ammonia and aprotonic polar solvents such as carboxylic acid amides, sulfolanes and sulfoxides. These solvents can be used either singly or as mixed systems consisting of two or more of them like mixed solvents such as ammonia-alcohol and dimethylsulfoxide-cellosolve. They can be chosen suitably as needed. Such solvents preferably have a water content as low as possible, notably a water content of 1.0 wt.% or less. Reaction temperatures not higher than 60°C are not preferred, because the reaction is extremely slow so that a long time is required for the preparation and the yield is very low. When the reaction is conducted generally at a temperature of 60°C or higher, preferably at a temperature of 80°C or higher, the reaction proceeds promptly and smoothly so that the target compound can be obtained in a high yield. However, if the reaction temperature exceeds about 200°C, the formation of byproducts suddenly increases to such an extent that these byproducts can no longer be ignored, and the purity of the product is lowered considerably. Reaction temperatures above 200°C are therefore not preferred. In the process of this invention for the preparation of the diguanamine, it is therefore preferred to conduct the reaction in a temperature range of 60-200°C, more preferably 80-180°C. In such a temperature range, byproducts are minimized and the target compound can be obtained with high purity, the preparation including the purification can be performed easily, and the target compound can be obtained in a higher yield. Although no particular limitation is imposed on the reaction system, the reaction can be carried out either under normal pressure or under naturally-occurring pressure or elevated pressure in a closed vessel. The reaction system can be suitably selected as needed. To obtain the diguanamine of the present invention, that is, the target compound from the reaction mixture of the above reaction, it is most desirable to cool the reaction mixture and collect the crystallized diguanamine by filtration. As an alternative, the reaction mixture may be poured, as is, into hot water, followed by crystallization and filtration. Unreacted dicyandiamine and/or dicarbonitrile, which accompany with the crude diguanamine, can be easily removed by washing the crude diguanamine with hot water or methanol. When further purification is required depending on the application purpose, the diguanamine can be purified further by subjecting to recrystallization in the above-described reaction solvent, for example, an alcohol, cellosolve, carboxylic acid amide, sulfolane or sulfoxide, a mixed solvent of such a solvent and water, or water; by dissolving it in the above-described reaction solvent and then pouring the resultant solution in hot water, thereby effecting reprecipitation; or by dissolving the crude diguanamine in an HCl-acidified aqueous solution and mixing the resulting solution with an alkali, thereby reprecipitating the diguanamine. Such additional purification is however not required practically in most instances, because the yield is extremely good in the process of this invention for the preparation of the diguanamine and, moreover, the diguanamine can be obtained with high purity sufficient for practical applications when washed simply with one of various solvents such as methanol, water, a mixed solvent thereof or the like. The diguanamine according to the present invention has excellent polymerizability with various compounds such as aldehydes, epoxy compounds, carboxylic acids and isocyanates and also has various excellent reactivity, so that the diguanamine is extremely useful as a raw material for resins and also as a raw material for derivatives. Moreover, diguanamine derivatives such as reaction products of the diguanamine with aldehydes, reaction products obtained by etherifying the first-mentioned reaction products with alcohols, and reaction products obtained by subjecting the first-mentioned and second-mentioned reaction products to condensation are particularly useful as curing agents and raw materials for various resins. Such diguanamine derivatives include, for example, the above-described derivatives: (f) N-methylol diguanamine obtained by subjecting the diguanamine described under (a) and an aldehyde to an addition reaction and represented by the following formula (5) or (6): wherein the bonding sites of the N-substituted-4,6-diamino-1,3,5-triazin-2-yl groups are the 2,5- or 2,6-positions, R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 individually represent one substituent selected from a hydrogen atom and an HOCH 2 group, and R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 may be the same or different, or wherein the bonding sites of the N-substituted-4,6-diamino-1,3,5-triazin-2-yl groups are the 1,2-, 1,3- or 1,4-positions, R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 have the same meaning as defined above, and R 2 , R 3 , R 4 , R 5 , R 6 , R 7 and R 8 may be the same or different; (g) etherified diguanamines each obtained by etherifying the N-methylol diguanamine described above under (f) with at least one alcohol selected from the group consisting of alcohols having 1-20 carbon atoms, containing at least one R 1 OCH 2 group, R 1 representing a residual group formed by removing a hydroxyl group from the alcohol, and represented by the following formula (7) or (8): wherein the bonding sites of the N-substituted-4,6-diamino-1,3,5-triazin-2-yl groups are the 2,5- or 2,6-positions, R 1 represents a residual group formed by removing a hydroxyl group from the alcohol, R 9 , R 10 , R 11 , R 12 , R 13 , R 14 and R 15 individually represent one substituent selected from a hydrogen atom and HOCH 2 and R 1 OCH 2 groups, and R 9 , R 10 , R 11 , R 12 , R 13 , R 14 and R 15 may be the same or different, or wherein the bonding sites of the N-substituted-4,6-diamino-1,3,5-triazin-2-yl groups are the 1,2-, 1,3- or 1,4-positions, R 1 represents a residual group formed by removing a hydroxyl group from the alcohol, R 9 , R 10 , R 11 , R 12 , R 13 , R 14 and R 15 have the same meaning as defined above, and R 9 , R 10 , R 11 , R 12 , R 13 , R 14 and R 15 may be the same or different; (h) primary condensates of the N-methylol diguanamine each obtained by subjecting the diguanamine described above under (a), a condensable compound as an optional reactant and an aldehyde to an addition condensation reaction, having an average addition condensation degree greater than 1 and containing at least one methylol group; and (i) primary condensates of the etherified diguanamine each obtained by subjecting the diguanamine described above under (a), a condensable compound as an optional reactant and an aldehyde to an addition reaction or an addition condensation reaction and then etherifying the reaction product with at least one alcohol selected from the group consisting of alcohols having 1-20 carbon atoms and optionally to a simultaneous condensation reaction, having an average addition condensation degree greater than 1 and containing at least one R 1 OCH 2 group, R 1 having the same meaning as defined above. Examples of the aldehydes used for the preparation of these derivatives include, but are not limited to, formaldehyde, paraformaldehyde, hexamethylenetetramine, methylhemiformal, butylhemiformal, formaldehyde-sodium bisulfite addition product, and glyoxal. Preferred are formaldehyde, formalin, paraformaldehyde, hexamethylenetetramine, methylhemiformal and butylhemiformal. Useful as the alcohols employed for the etherification in the preparation of these derivatives are alcohols such as saturated or unsaturated aliphatic alcohols having 1-20 carbon atoms, alicyclic alcohols, alcohols containing one or more ether groups, and alcohols containing one or more aromatic groups. Examples of such alcohols include, but are not limited to, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-alcohol, n-hexyl alcohol, sec-heptyl alcohol, 2-ethylhexyl alcohol, n-nonyl alcohol, n-hexadecyl alcohol, n-octadecyl alcohol, n-eicosyl alcohol, cyclohexyl alcohol, cyclohexenyl alcohol, 4-methylhexyl alcohol, 4-hexylcyclohexyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, and benzyl alcohol. In the preparation of these derivatives, co-condensable compounds can be used in some instances as described above. Examples of such co-condensable compounds include, but are not limited to, melamine, urea, alkylureas, thiourea, alkylthioureas, aniline, and guanamines such as benzoguanamine and cyclohexylcarboguanamine. In the case of the N-methylol diguanamine described above, the reaction proceeds promptly and smoothly to provide the derivative with at least one HOCH 2 group when the reaction is conducted, for example, in a solvent and, if necessary, in the presence of a basic compound, at pH 8.0-13.0, preferably pH 8.5-11.5 and a reaction temperature of not lower than 30°C, preferably 40-80°C. To obtain an N-methylol diguanamine with a high degree of methylol derivation, the derivative can be obtained with high purity and in a high yield when the reaction is conducted using water and the alcohol in smaller amounts. Use of water and the alcohol in appropriate amounts, however, leads to a reduction in the stirring effects, unevenness in the reaction temperature, etc., thereby making it difficult to smoothly proceeding with the reaction. It is hence not preferred to reduce the amounts of water and the alcohol. To allow the reaction to proceed smoothly, it is effective to conduct the reaction in the presence of a solvent substantially insoluble in water and free from inhibition to the reaction, for example, an aromatic hydrocarbon such as toluene, xylene, ethylbenzene, cumene or benzene, an aliphatic hydrocarbon such as hexane, heptane, octane or cyclohexane, a halogenated hydrocarbon such as dichloromethane or a aliphatic ether such as diisopropyl ether; or to add an amine as an aid, for example, an aliphatic amine such as hexamethylenetetramine, piperazine or piperidine, an aliphatic amine such as triethylamine, diethylamine, dibutylamine or hexylamine, an aromatic amine such as pyridine or aniline, or ammonia in an amount of 0.01-10 mole% based on the aldehyde. The reaction can be performed by suitably choosing these methods as needed. It is however to be noted that the practice of the reaction is not necessarily limited to the use of such methods. The etherified diguanamine described above can be obtained, for example, by reacting the above-obtained N-methylol diguanamine for 1-8 hours under acidic conditions of pH 2-4 at a temperature of 40-80°C in the presence of the alcohol with which an etherification reaction is to be conducted. It is particularly preferred to conduct the etherification by reducing the amount of water in the reaction system as much as possible and charging the reactants at a ratio of at least 20 moles of the alcohol to each mole of the N-methylol diguanamine. The primary condensate of N-methylol diguanamine described above can be obtained, for example, by reacting with the aldehyde at a temperature of 40-100°C under conditions of pH 8.0 or lower or pH 13.0 or higher. Further, the primary condensate of etherified diguanamine can be obtained, for example by subjecting the N-methylol diguanamine or the primary condensate of N-methylol diguanamine to etherification or to both etherification and condensation under acidic conditions of pH 1.0-5.0 at a temperature of 50-100°C in the presence of the alcohol with which an etherification reaction is to be conducted. It is however to be noted that the preparation process is not limited to that described above. The N-methylol diguanamine, etherified diguanamine, primary condensate of N-methylol diguanamine and primary condensate of etherified diguanamine have excellent reactivity with compounds and resins having various kinds of functional groups and are extremely useful as curing agents for various resins and also as intermediates for resin raw materials. For example, it is possible to provide a thermosetting composition which comprises at least one derivative selected from the group consisting of the derivatives (f), (g), (h) and (i). Although such compositions are useful as adhesives, crease resistant finishing agents for fibers, for example, synthetic fibers such as polyester fibers and acrylic fibers and natural fibers such as cotton and wool, excellent surface improving agents for antifouling agents, paper coating agents and hide treatments even if these derivatives alone are contained as curing components, these diguanamine derivatives can be reacted further with those containing one or more hydroxyl, carboxyl, isocyanate and/or epoxy groups so that resins having excellent properties can be obtained. In combination with various polymers such as acrylic resins, epoxy resins, polyester resins, urethane resins, aminoalkyd resins, phenol resins, fluorinated resins and vinyl resins, the above derivatives can provide thermosetting compositions extremely useful as chain extenders, crosslinking agents, curing agents, denature agents and/or modifiers. They are accordingly useful for a wide variety of application fields, for example, as adhesive resins, paint resins and building resins. Especially, thermosetting compositions comprising at least one derivative, which is selected from the group consisting of the N-methylol diguanamines, etherified diguanamines, primary condensates of the N-methylol diguanamines and primary condensates of the etherified diguanamines, and a resin curable through a reaction with the derivative are useful as resins for paints such as water-base paints and oil-base paints. The resin curable through a reaction with such a derivative can be any resin having functional groups capable of reacting with the derivative so that the resin is cured. For example, resins containing at least one type of groups selected from hydroxyl groups, carboxyl groups, epoxy groups, methylolamido groups, alkoxymethylolamido groups and isocyanate groups are useful. Examples of such resins include, but are not limited to, acrylic resins, epoxy resins, polyester resins, phenol resins, phenol-alkyd resins, urethane resins, fluorinated resins, silicone resins, and modified resins thereof. The diguanamines according to the present invention can provide thermosetting resin compositions which comprise, as essential components, at least one diguanamine selected from the diguanamines described above and an epoxy-containing resin. A conventional composition comprising an epoxy-containing resin and an amine as a curing agent cures at relatively low temperatures but, because the amine used as a curing agent is chemically active, the amine reacts with the epoxy-containing resin when they are stored as a mixture. This has resulted in the drawback that the composition has a shorter pot life and its handling is difficult. A composition containing dicyandiamide as a curing agent has relatively good storage stability, but articles obtained by curing the composition are accompanied by the drawbacks that their properties such as flexibility and light resistance are not good. Considerable limitations are therefore imposed on the use of such compositions. With these drawbacks in view, the present inventors have proceeded with an extensive investigation. As a result, they have found the above-described thermosetting resin compositions which have excellent storage stability and can provide cured resin articles having excellent properties as cured products such as excellent flexibility and light resistance. These thermosetting resin compositions are useful for a wide variety of applications, for example, as IC packaging materials, adhesives, powder coatings, oil-base paints, electric insulating materials and the like. Any epoxy-containing resin can be used widely in this invention insofar as it contains at least one epoxy group. In general, a polyepoxide containing at least two epoxy groups per molecule is preferred. Although no particular limitations are imposed on the epoxy-containing resins, illustrative exemplary epoxy-containing resins include, but are not limited to, diglycidyl ether type epoxy resins of bisphenol A; butadiene epoxide; 4,4-di(1,2-epoxyethyl)diphenyl ether; 4,4'-di(epoxyethyl)biphenyl, diglycidyl ether of resorsine; diglycidyl ether of fluoroglycine; triglycidyl ether of p-aminophenol; triglycidyl ether of m-aminophenol; tetraglycidyl-bis-(aminophenol)methane; 1,3,5-tri(1,2-epoxyethyl)benzene; 2,2,4,4-tetra-glycidoxybenzophenone; tetraglycidoxytetraphenylethane; polyglycidyl ethers of novolak phenol-formaldehyde resins; triglycidyl ether of trimethylolpropane; triglycidyl ether of glycerin; diglycidyl ether type epoxy resins of halogenated bisphenol A; polyglycidyl ethers of halogenated novolak phenol-formaldehyde resins; cycloaliphatic epoxy resins such as vinylcyclohexene dioxide and 3,4-epoxycyclohexylmethyl 3,4-epoxyclohexanecarboxylate; heterocyclic epoxy resins such as hydantoin epoxy resin and triglycidyl isocyanurate; polymers of epoxy-containing vinyl monomers, such as glycidyl acrylate and glycidyl methacrylate, with copolymerizable vinyl monomers such as acrylate esters, methacrylate esters, fumarate esters, maleate esters, acrylamides, methacrylamides, acrylonitrile, methacrylonitrile, styrenes, butadienes and vinyl esters; and modified polymers thereof. Where a high-molecular, bisphenol A-diglycidyl ether type epoxy resin cannot be used for its high viscosity in the present invention, the resin can be modified using as a modifier such as a low-molecular bisphenol A-glycidyl ether type epoxy resin, bisphenol A, bisphenol S, brominated bisphenol A or brominated bisphenol S. The mixing ratio of the diguanamine according to this invention to the epoxy-containing resin can be suitably selected depending on the application. In general, however, the diguanamine is used in an amount of 0.2-3.0 equivalents, preferably 0.4-1.5 equivalents per equivalent of epoxy groups in the epoxy-containing resin. For each thermosetting resin composition according to the present invention, a curing accelerator such as a novolak type phenol resin, a metal salt of an organic acid or imidazole can be suitably chosen and mixed. Use of such a curing accelerator is preferred especially where a novolak type phenol resin is used, because a thermosetting resin composition excellent in storage stability and curability can be obtained. Examples of the novolak type phenol resin include, but are not limited to, those produced by a process known per se in the art from a phenol such as phenol, cresol, xylenol, ethylphenol, butylphenol, p-phenylphenol, non-ylphenol, bisphenol A, resorcinol or chlorophenol and an aldehyde such as formaldehyde or paraformaldehyde. Although the mixing proportion of the novolak type phenol resin is generally 0.1-10 parts by weight per 100 parts by weight of the epoxy-containing resin, it can be suitably chosen as needed. The thermosetting resin compositions according to the present invention can each be obtained by mechanically mixing a raw material batch, which is composed of the diguanamine, the epoxy-containing resin and, if necessary, other optional components in prescribed mixing proportions, within a Z-blade mixer, extruder, dry ball mill or the like to a sufficient extent. Further, the mixture so obtained can be subjected to melt mixing by hot rolls or the like in some instances. The diguanamine according to the present invention, however, has a high melting point so that the mixture may not flow evenly or the resulting cured article may not be homogeneous. Even when such melt mixing is not preferred, a thermosetting resin composition in a fully compatibilized form can still be obtained, for example, by heating, melting and mixing the diguanamine in advance together with a low-viscosity diluent, a solbilizing agent, a novolak type phenol resin, etc., adding an epoxy-containing resin to the resultant melt and then mixing them under heat, by dissolving and mixing the guanamine and the epoxy-containing resin in a solvent, or by removing the solvent from the mixed solution. These methods can be suitably chosen as needed. It is to be noted that the present invention is not necessarily limited to any of these methods. Besides the diguanamine and epoxy-containing resin described above, each thermosetting resin composition according to the present invention can be added, as needed, with an inorganic filler, for example, silica powder, alumina, antimony trioxide, talc, calcium carbonate, titanium white, clay, mica, red oxide, glass fibers or carbon fibers; a mold release agent such as a natural wax, a synthetic wax, a metal salt of a fatty acid, an acid amide, an ester or a paraffin; a flame retardant such as chlorinated paraffin, bromotoluene, hexabromobenzene or antimony trioxide; a colorant such as carbon black or red oxide; a silane coupling agent; a flexibilizer; a viscosity-reducing diluent; one or more of various curing accelerators; etc. Each diguanamine according to the present invention can provide compounds and resins such as polyamic acids, polyimides and polyamides, all having excellent properties, when reacted with carboxylic acids, for example, phthalic acid, adipic acid, maleic acid, trimellitic acid, ethylenetetracarboxylic acid, cyclopentanetetracarboxylic acid, pyrromellitic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 2,2',3,3'-benzophenonetetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,2',3,3'-biphenyltetracarboxylic acid, 2,2-bis(3,4-dicarboxyphenyl)propane, bis(2,3-dicarboxyphenyl)methane, 2,3,6,7-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 1,2,3,4-benzenetetracarboxylic acid, 2,3,6,7-anthracenetetracarboxylic acid and 1,2,7,8-phenanthrenetetracarboxylic acid; or with their precursors, i.e., partial cesters, acid anhydrides, halogenoacylates and the like. Further, each diguanamine according to the present invention can provide compounds and resins such as polyurea, all having excellent properties, when reacted with isocyanates, for example, 1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, diisocyanates derived from dimeric acids, bis(2-isocyanatoethyl) fumarate, methylcyclohexane-2,4-diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isopropylidene bis(4-cyclohexylisocyanate), xylylene diisocyanate, m-phenylene diisocyanate, tolidine diisocyanate, dianisidine diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and the like, or with polyisocyanates which have been obtained by reacting such isocyanates with polyols, amines, water or the like. In addition, each diguanamine according to the present invention can also provide resins having excellent properties when reacted with compounds containing one or more N-substituted unsaturated imido groups, for example, with monophenylmaleimide, monophenylcitraconimide, monophenylitaconimide, 2-chlorophenylmaleimide, 2,6-dichlorophenylmaleimide, 2-methylphenylmaleimide, 2,6-dimethylphenylmaleimide, 4-hydroxyphenylmaleimide, N,N'-ethylenebismaleimide, N,N'-hexamethylenebismaleimide, N,N'-dodecanemethylenebismaleimide, N,N'-m-phenylenebismaleimide, N,N'-p-phenylenebismaleimide, N,N'-p-phenylenebiscitraconimide, N,N'-p-phenylenebisitaconimide, N,N'-p-phenylene-endomethylenetetrahydrophthalimide, N,N'-4,4'-diphenylmethanebismaleimide, 2,2-bis-[4-(4-maleimidophenoxy)phenyl]propane, N,N'-4,4'-dicyclohexylmethanebismaleimide, N,N'-m-xylenebismaleimide, N,N'-diphenylcyclohexanebismaleimide, 4,4'-bismaleimidocinnamanilide, 4,4'-methylene-bis(2-isopropyl-6-methyl-phenylmaleimide) and 2,2-bis[4-(4-maleimidophenoxy)phenyl]hexafluoropropane. Further, each diguanamine according to the present invention can also be used as metallic chain extenders, crosslinking agents, curing agents, high-molecular modifiers and the like, which have excellent properties, for various polymers such as urethane resins and epoxy resins. It is however to be noted that the use of each diguanamine is not limited to them. As has been described above, the diguanamines according to the present invention have excellent reactivity and polymerizability with various compounds. Such polymerizations, reactions and the like can be conducted by any polymerization or reaction process such as solution polymerization, emulsion polymerization, suspension polymerization, bulk polymerization, interfacial polymerization, solution reaction or water-system reaction. A suitable polymerization or reaction process can be chosen as needed. The diguanamines according to the present invention have specific inherent properties such that they are excellent in weatherability, ultraviolet light resistance and the like and can retain initial performance outdoors over a long time, their methylol derivatives are extremely good in water reducibility and have excellent properties as raw materials for water-base resins without any substantial limitation, they contain active amino groups having extremely good reactivity with aldehydes, epoxy compounds, carboxylic acids, isocyanates and the like, and owing to the inclusion of eight active hydrogen atoms, permit the selection of a methylol derivation degree from a wide range. Moreover, they can provide various guanamine derivatives and resins having excellent properties such as flexibility, toughness, high hardness, waterproofness and curability and can show superb performance, so that they are extremely useful compounds. When the specific compounds described above are used and the reaction catalyst, solvent, reaction temperature, the molar ratio of the raw materials and the like are suitably selected, the process of the present invention for the preparation of the diguanamine can obtain the target product with high purity while substantially minimizing byproducts. The preparation process including the purification step is simple, can substantially reduce the loss of the raw materials, can obtain the target product in a high yield from the raw materials available economically, and therefore is excellent in technology and economy and has extremely high practical utility. Such diguanamines have excellent polymerizability with various compounds such as aldehydes, epoxy compounds, carboxylic acids and isocyanates and also have various superb reactivity. They are hence extremely useful as raw materials for resins and derivatives. They can provide, for example, derivatives extremely useful as curing agents for various resins and also as intermediates for resin raw materials, such as N-methylol diguanamines obtained by reacting the diguanamines with aldehydes, etherified diguanamines obtained by subjecting the N-methylol diguanamine derivatives and alcohols to etherification, and their initial condensates; thermosetting compositions comprising these derivatives; and thermosetting resin compositions comprising the above diguanamines and epoxy-containing resins, said compositions being useful as IC packaging material resins, paint resins and adhesive resins. The diguanamines according to the present invention are excellent compounds capable of providing guanamine derivatives, resins and compositions, which are industrially useful in an extremely wide range of fields as rubber modifiers, optical materials, resist materials, electrical insulating materials, paints for home electric and electronic appliances, automotive paints, antifouling paints, anticorrosion paints, weatherable paints, fluorescent paints, powder coatings, water-base paints, oil-base paints, building materials, IC packaging materials, paper coating agents, fiber treatments for antifouling treatment of interior items such as curtains, sofas, wall cloths and carpets and also for water vapor barrier treatment, sweat absorption treatment, SP treatment, wrinkle resistance treatment, water- and oil-repellant treatment of fibers, adhesive resins, hide treatments, plastic magnets, latex antioxidants, anticorrosion agents, electrophotographic photoconductors, surfactants, agricultural chemicals, medicines, and the like. The present invention will next be described in detail by the following referential examples and examples. It should however be borne in mind that this invention is by no means limited to or by these referential examples and examples. Referential Example 1 Preparation of a dicarbonitrile (3) In a 500-mℓ flask equipped with a stirrer, a thermometer, a liquid inlet tube and a condenser, 297.92 g (2.50 moles) of bicyclo[2.2.1]hepta-5-ene-2-carbonitrile, 8.77 g (6.75 mmoles) of Ni[P(OC 6 H 5 ) 3 ] 4 , 4.80 g (35.22 mmoles) of ZnCl 2 and 32.27 g (0.104 mole) of P(OC 6 H 5 ) 3 were charged. After the flask was fully purged with nitrogen gas, the reaction mixture was maintained at 65°C under stirring. Into the flask, 94.59 g (3.50 moles) of ice-cooled liquid hydrocyanic acid were then charged at a flow rate of 45-55 mℓ/hr over three hours, followed by a further reaction for one hour. The flask was again purged with nitrogen gas, followed by the addition of deionized water. The water layer so obtained was removed, whereby an oil was obtained in a semi-solid form. The oil was filtered and then was subjected to vacuum distillation, whereby 362.20 g of a mixture of bicyclo[2.2.1]heptane-2,5-dicarbonitrile and bicyclo[2.2.1]heptane-2,6-dicarbonitrile were obtained at 129-137°C/1 mmHg (yield: 99.01%). The following is the results of an elemental analysis of the target product. Elemental analysis: C H N Found: 73.9% 6.9% 19.2% Calculated: 73.94% 6.90% 19.16% Referential Example 2 Preparation of bicyclo[2.2.1]heptane-2,5-dicarbonitrile In a 2-ℓ flask equipped with a stirrer, a thermometer and a reflux condenser, 179.0 g (1.2 moles) of 5-cyano-bicyclo[2.2.1]hepta-2-carbaldehyde, 292.6 g (1.3 moles) of N,O-bis(trifluoroacetyl)hydroxylamine, 197.8 g (2.5 moles) of pyridine and 600 mℓ of benzene were charged. The resulting mixture was gradually heated and refluxed for 3 hours under stirring. Deionized water (500 mℓ) was thereafter added to the reaction mixture. The water layer so obtained was removed, whereby an oil was obtained. The oil was distilled under reduced pressure, whereby 128.0 g of bicyclo[2.2.1]heptane-2,5-dicarbonitrile were obtained at 131-136°C/1 mmHg (yield: 73%). The following is the results of an elemental analysis of the target product. Elemental analysis: C H N Found: 74.0% 6.9% 19.1% Calculated: 73.94% 6.90% 19.16% Referential Example 3 Preparation of a dicarbonitrile (4) In a 500-mℓ flask equipped with a stirrer, a thermometer, a gas inlet tube and a condenser, 188.6 g of 4-cyanocyclohexene, 6.0 g of Ni[P(OC 6 H 5 ) 3 ] 4 , 3.0 g of ZnCl 2 and 23.9 g of P(OC 6 H 5 ) 3 were charged. After the flask was fully purged with nitrogen gas, the reaction mixture was maintained at 75°C under stirring. Into the flask, nitrogen-diluted hydrocyanic acid gas having a concentration of 42 mole% was then charged at a rate of 177.0 mmoles/hour for seven hours. After the flask was again purged with nitrogen gas, the reaction mixture was cooled. As a result of its analysis, a dicarbonitrile (4) was obtained in a yield of 64.9%. Water and ethyl acetate, each 500 g, were added to the reaction mixture. After the resulting mixture was left over under stirring for 5 hours, the organic layer was separated. Ethyl acetate was then caused to evaporate, followed by vacuum distillation at 0.5-1.0 mmHg, whereby 132.0 g of a mixture of 1,3-cyclohexane dicarbonitrile and 1,4-cyclohexane dicarbonitrile were obtained as a 120-130°C fraction. As a result of its analysis, the fraction was found to consist of 64.4% of 1,3-cyclohexane dicarbonitrile and 35.6% of 1,4-cyclohexane dicarbonitrile. The following is the results of an elemental analysis of the target product. Elemental analysis: C H N Found: 71.5% 7.6% 20.9% Calculated: 71.61% 7.51% 20.88% Example 1 Preparation of a diguanamine (1) In a 3-ℓ flask equipped with a stirrer, a thermometer and a reflux condenser, 146.2 g (1.0 mole) of the dicarbonitrile (3) prepared in the same manner as in Referential Example 1, 210.2 g (2.5 moles) of dicyandiamide, 16.8 g of potassium hydroxide and 1,000 mℓ of methyl cellosolve were charged, followed by gradual heating. The reaction mixture became transparent as its temperature arose. When the temperature approached about 105°C, the reaction proceeded rapidly with substantial exotherm so that the solvent was refluxed. Some time after the reflux started, the reaction mixture became turbid. The resulting mixture was reacted at 120-125°C for 10 hours under stirring. Subsequent to removal of the solvent from the reaction mixture, 3 ℓ of deionized water were poured. The resulting white precipitate was collected by filtration. The solid so obtained was washed with deionized water and then with methanol, followed by vacuum drying. The resulting solid was dissolved in ethyl cellosolve, to which deionized water was added to conduct precipitation. The precipitate was collected by filtration. The solid so obtained was washed with water and then dried in a vacuum, whereby 2,5-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane and 2,5-bis(4,6-diamino-1,3,5-triazin-2-yl)bicyclo[2.2.1]-heptane were obtained as a mixture in the form of white powdery crystals having a melting point of 317-324°C (as measured by DSC). Incidentally, as a result of an analysis of the reaction mixture (before treatment) by liquid chromatography, it was found that, based on the amount of the dicarbonitrile (3) charged, the yield (mole%) of the diguanamine (1) was 98.2% and that of compounds other than the raw materials and the target compound was 0.08 wt.%. The results of an elemental analysis and 1 H nuclear magnetic resonance spectrum analysis of the target compound are presented below. In addition, the results of an infrared ray absorption spectrum analysis and mass spectrum analysis of the target compound are shown in FIG. 1 and FIG.2, respectively. Elemental analysis: C H N Found: 49.7% 5.8% 44.5% Calculated: 49.67% 5.77% 44.56% 1 H Nuclear magnetic resonance spectrum analysis (internal standard substance : TMS, solvent: d 6 -DMSO) Absorption based on NH 2 groups, δ 6.50 ppm (singlet), 6.72 ppm (singlet) Example 2 Preparation of 2,5-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane In a similar manner to Example 1 except that 146.2 g (1.0 mole) of the dicarbonitrile (3) prepared in the same manner as in Referential Example 1 were replaced by 160.8 g (1.1 moles) of bicyclo[2.2.1]heptane-2,5-dicarbonitrile prepared in the same manner as in Referential Example 2, a reaction was conducted and the resulting reaction mixture was treated. The solid so obtained was subjected to vacuum drying, whereby 2,5-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]-heptane was obtained as white powdery crystals having a melting point of 318-321°C (as measured by DSC). Incidentally, as a result of an analysis of the reaction mixture (before treatment) by liquid chromatography, it was found that the yield of the diguanamine (1) was 96.4 mole% based on the amount of the dicarbonitrile (3) charged. In an infrared absorption spectrum of the target compound, the nitrile-based absorption (at 2235 cm -1 ) of the raw material compound disappeared and instead, a triazine-ring-based absorption was observed at 821 cm -1 . Its elemental analysis data were found to conform well with the calculated values as shown below. Elemental analysis: C H N Found: 49.7% 5.7% 44.6% Calculated: 49.67% 5.77% 44.56% Example 3 Preparation of a diguanamine (2) In a 3-ℓ flask equipped with a stirrer, a thermometer and a reflux condenser, 134.2 g (1.0 mole) of the dicarbonitrile (4) prepared in the same manner as in Referential Example 3, 210.2 g (2.5 moles) of dicyandiamide, 16.8 g of potassium hydroxide and 1,000 mℓ of methyl cellosolve were charged, followed by gradual heating. The reaction mixture became transparent as its temperature arose. When the temperature approached about 105°C, the reaction proceeded rapidly with substantial exotherm so that the solvent was refluxed. Some time after the reflux started, the reaction mixture became turbid. The resulting mixture was reacted at 120-125°C for 10 hours under stirring. Subsequent to the removal of the solvent from the reaction mixture, 3 ℓ of deionized water were poured. The resulting white precipitate was collected by filtration. The solid so obtained was washed with deionized water and then with methanol, followed by vacuum drying. The resulting solid was dissolved in ethyl cellosolve, to which deionized water was added to induce reprecipitation. The precipitate so formed was collected by filtration. The solid so obtained was washed with water and then dried in a vacuum, whereby 1,3-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane and 1,4-bis(4,6-diamino-1,3,5-triazin-2-yl)cyclohexane were obtained as a mixture in the form of white powdery crystals having a melting point of 317-321°C (as measured by DSC). Incidentally, as a result of an analysis of the reaction mixture (before treatment) by liquid chromatography, it was found that, based on the amount of the dicarbonitrile (4) charged, the yield of the diguanamine (2) was 97.3 mole% and that of the compound(s) except the raw materials and the target compound was 0.12 wt.%. The results of an elemental analysis and 1 H nuclear magnetic resonance spectrum analysis of the target compound are presented below. In addition, the results of an infrared ray absorption spectrum analysis and a mass spectrum analysis of the target compound are shown in FIG. 3 and FIG. 4, respectively. Elemental analysis: C H N Found: 47.6% 6.1% 46.3% Calculated: 47.67% 6.00% 46.33% 1 H Nuclear magnetic resonance spectrum analysis (internal standard substance: TMS, solvent: d 6 -DMSO) Absorption based on NH 2 groups, δ: 6.49 ppm (singlet) Example 4 Preparation of 1,4-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane In a similar manner to Example 3 except that 134.2 g (1.0 mole) of the dicarbonitrile (4) prepared in the same manner as in Referential Example 3 were replaced by 147.6 g (1.1 moles) of 1,4-cyclohexane dicarbonitrile, a reaction was conducted and the resulting reaction mixture was treated. The solid so obtained was subjected to vacuum drying, whereby 1,4-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane was obtained as white powdery crystals having a melting point of 319-322°C (as measured by DSC). Incidentally, as a result of an analysis of the reaction mixture (before treatment) by liquid chromatography, it was found that, based on the amount of the dicarbonitrile (4) charged, the yield of the diguanamine (2) was 95.8 mole%. In an infrared absorption spectrum of the target compound, it was found that the nitrile-based absorption (at 2237 cm -1 ) of the raw material compound disappeared and instead, a triazine-ring-based absorption was newly observed at 821 cm -1 . Its elemental analysis data were found to conform well with the calculated values as shown below. Elemental analysis: C H N Found: 47.7% 6.1% 46.2% Calculated: 47.67% 6.00% 46.33% 1 H Nuclear magnetic resonance spectrum (internal standard substance: TMS, solvent: d 6 -DMSO) Absorption based on NH 2 groups δ: 6.50 ppm (singlet) Example 5 Preparation of 1,2-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane In a similar manner to Example 3 except that 134.2 g (1.0 mole) of the dicarbonitrile (4) prepared in the same manner as in Referential Example 3 were replaced by 134.2 g (1.0 mole) of 1.2-cyclohexane dicarbonitrile, a reaction was conducted and the resulting reaction mixture was treated. The solid so obtained was subjected to vacuum drying, whereby 1,2-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane was obtained as white powdery crystals. In an infrared absorption spectrum of the target compound, the nitrile-based absorption of the raw material compound disappeared and instead, a triazine-ring based absorption was newly observed. Its elemental analysis data were found to conform well with the calculated value as shown below. Elemental analysis: C H N Found: 47.7% 6.0% 46.3% Calculated: 47.67% 6.00% 46.33% Example 6 Preparation of diguanamines (1) In a similar manner to Example 1 except that the charged amount (in moles) of dicyandiamide and the reaction solvent were changed, reactions were conducted and the reaction mixtures so obtained were treated. The yields of the target compounds, diguanamines (1), are shown in Table 1. Amount of dicyandiamide charged (moles) Reaction solvent Yield of diguanamine (1) [based on dicarbonitrile (3) charged (mole%)] Example 6-1 2.2 Ethyl cellosolve 95.8 Example 6-2 2.5 Ethylene glycol 97.0 Example 6-3 2.5 A mixed solvent of dimethyl sulfoxide/methyl cellosolve (weight ratio:1/1) 98.2 Example 7 Preparation of a diguanamine (1) In a 3-ℓ flask equipped with a stirrer, a thermometer and a reflux condenser, 146.2 g (1.0 mole) of the dicarbonitrile (3) obtained in the same manner as in Referential Example 1, 210.2 g (2.5 moles) of dicyandiamide, 54.0 g of sodium methylate and 1,000 mℓ of dimethyl sulfoxide were charged, followed by gradual heating. When the temperature approached about 105°C, the reaction proceeded rapidly with substantial exotherm. The temperature was thereafter raised gradually to 140°C, followed by reaction at 140-145°C for 2 hours under stirring. The reaction mixture so obtained was treated in a similar manner to Example 1, whereby 2,5-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane and 2,6-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane was obtained as a mixture. Incidentally, as a result of an analysis of the reaction mixture (before treatment) by liquid chromatography, it was found that, based on the amount of the dicarbonitrile (3) charged, the yield of the diguanamine (1) was 99.7 mole%. Example 8 Preparation of diguanamines (2) In a similar manner to Example 3 except that the charged amount (in moles) of dicyandiamide and the reaction solvent were changed, reactions were conducted and the reaction mixtures so obtained were treated. The yields of the target compounds, diguanamines (2), are shown in Table 2. Amount of dicyandiamide charged (moles) Reaction solvent Yield of diguanamine (2) [based on dicarbonitrile (4) charged (mole%)] Example 8-1 2.5 Isopropyl cellosolve 96.1 Example 8-2 1.7 N,N-dimethylacetamide 61.5 Example 8-3 2.5 Sulforan 98.2 Example 8-4 3.0 A mixed solvent of dimethyl sulfoxide/methyl cellosolve (weight ratio:1/1) 98.6 Example 9 Preparation of 1,4-bis(4,6-diamino-1,3,5-triazin-2-yl)cyclohexane In a 3-ℓ flask equipped with a stirrer, a thermometer and a reflux condenser, 134.2 g (1.0 mole) of 1,4-cyclohexane dicarbonitrile, 210.2 g (2.5 moles) of dicyandiamide, 54.0 g of sodium methylate and 1,000 mℓ of dimethyl sulfoxide were charged, followed by gradual heating. The reaction mixture became transparent as its temperature arose. When the temperature approached about 105°C, the reaction proceeded rapidly with substantial exotherm. The temperature was thereafter raised to 140°C, followed by reaction at 140-145°C for 2 hours under stirring. The reaction mixture so obtained was treated in a similar manner to Example 3, whereby 1,4-bis(4,6-diamino-1,3,5-triazin-2-yl)-cyclohexane was obtained as white powdery crystals. Incidentally, as a result of an analysis of the reaction mixture (before treatment) by liquid chromatography, it was found that the yield of the diguanamine (2) was 99.1 mole% based on the amount of the dicarbonitrile (4) charged. According to the preparation process of the present invention which can provide a diguanamine by reacting a particular dicarbonitrile and dicyandiamide while suitably selecting a reaction catalyst, a solvent, a reaction temperature, the molar ratio of the raw materials and/or the like, the target compound can be obtained with extremely minimized byproducts and high purity and in a high yield as demonstrated above in Examples 1-9. The process, including the purification step, is easy to practice and is excellent. Example 10 Preparation of an N-methylol derivative of a diguanamine (1) and water dilution test of the derivative To 15.7 g (0.05 mole) of the diguanamine (1) obtained in the same manner as in Example 1, 42.2 g of 37% formalin (0.52 mole in terms of 100 % formaldehyde) which had been adjusted to pH 10.5 with a 10% aqueous solution of sodium hydroxide were added. The resulting mixture was heated at 60-65°C for 30 minutes under stirring. The reaction mixture was homogeneous and clear. As a result of its analysis, it was found that 7.2 moles of formaldehyde were methylol-bonded to one mole of the diguanamine (1). To the resulting solution of the N-methylol derivative, 50 g of deionized water were gradually added at room temperature. The solution so obtained was also homogeneous and clear. Example 11 Preparation of an N-methylol derivative of a diguanamine (2) and a water dilution test of the derivative To 15.1 g (0.05 mole) of the diguanamine (2) obtained in the same manner as in Example 3, 42.2 g of 37% formalin (0.52 mole in terms of 100% formaldehyde) which had been adjusted to pH 10.5 with a 10% aqueous solution of sodium hydroxide were added. The resulting mixture was heated at 60-65°C for 30 minutes under stirring. The reaction mixture was homogeneous and clear. As a result of its analysis, it was found that 7.3 moles of formaldehyde were methylol-bonded to one mole of the diguanamine (2). To the resulting solution of the N-methylol derivative, 50 g of deionized water were gradually added at room temperature. The solution so obtained was also homogeneous and clear. As demonstrated in Examples 10 and 11, the N-methylol derivative of each diguanamine according to the present invention has been found to have excellent water reducibility so that it is excellent as a raw material for a resin to be used in an aqueous system such as a water-base paint resin and is extremely useful for a wide variety of applications. Comparative Example 1 Preparation of an N-methylol derivative of phthaloguanamine and a water dilution test of the derivative In a similar manner to Example 10 except 14.8 g (0.05 mole) of o-phthaloguanamine were used instead of 15.7 g (0.05 mole) of the diguanamine (1) obtained in the same manner as in Example 1, a reaction was conducted. The reaction mixture contained a large amount of an insoluble solid so that it was subjected to solid-liquid separation by hot filtration. The solid was dried under reduced pressure, whereby 13.7 g of crystals, which were found to contain 13.6 g (0.046 mole) of o-phthaloguanamine as a result of an elemental analysis, were obtained. Deionized water (1.0 g) was then added to the filtrate at room temperature, whereby substantial turbidity occurred. Comparative Example 2 Preparation of an N-methylol derivative of spiroguanamine and a water dilution test of the derivative In a similar manner to Example 10 except 15.7 g (0.05 mole) of the diguanamine (1) obtained in the same manner as in Example 1 were replaced by 21.7 g (0.05 mole) of 3,9-bis[2-(3,5-diamino-2,4,6-triazaphenyl)ethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane] ("CTU guanamine"; product of Ajinomoto Co., Inc.), a reaction was conducted. The reaction mixture so obtained contained a large amount of an insoluble solid so that it was subjected to solid-liquid separation by hot filtration. The solid was dried under reduced pressure, whereby 18.3 g of crystals, which were found to contain 18.2 g (0.042 mole) of CTU guanamine as a result of an elemental analysis, were obtained. Deionized water (1.0 g) was then added to the filtrate at room temperature, whereby substantial turbidity occurred. As have been demonstrated above in Comparative Examples 1 and 2, methylol-forming reaction of phthaloguanamine and spiroguanamine with aldehydes are extremely slow. The amino groups in such compounds have poor reactivity, so that it is difficult to produce resin intermediates, such as co-condensates with melamine, guanamines or ureas, or various derivatives. Further, the N-methylol derivatives of such compounds have extremely poor water reducibility. It is hence difficult to employ them as raw materials for resins to be used in aqueous systems, such as water-base paint resins. Moreover, substantial limitations are imposed on their applications. Example 12 Preparation of an N-methylol derivative of a diguanamine (1) To 15.7 g (0.05 mole) of the diguanamine (1) obtained in the same manner as in Example 1, 17.9 g of 37% formalin (0.22 mole in terms of 100% formaldehyde) which had been adjusted to pH 9.0 with a 5% aqueous solution of sodium carbonate were added. The resulting mixture was heated at 70-75°C for 30 minutes under stirring. The reaction mixture was clear. As a result of an analysis of the mixture, it was found that 4.0 moles of formaldehyde were methylol-bonded with one mole of the diguanamine (1). Example 13 Preparation of an N-methylol derivative of a diguanamine (1) To 15.7 g (0.05 mole) of the diguanamine (1) obtained in the same manner as in Example 1, 19.9 g (0.32 mole) of methylhemiformal and 40.0 g of methanol were added, followed by the adjustment to pH 9.5 with a 20% aqueous solution of potassium hydroxide. The resulting mixture was heated at 60°C for one hour under stirring. The reaction mixture was clear. As a result of an analysis of the mixture, it was found that 6.1 moles of formaldehyde were methylol-bonded with one mole of the diguanamine (1). Example 14 Preparation of an N-methylol derivative of a diguanamine (1) To 15.7 g (0.05 mole) of 2,5-bis(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane obtained in the same manner as in Example 2, 81.2 g of 37% formalin (1.0 mole in terms of 100% formaldehyde) which had been adjusted to pH 10.5 with a 5% aqueous solution of sodium hydroxide were added. The resulting mixture was heated at 60°C for one hour under stirring. The reaction mixture was clear. As a result of an analysis of the mixture, it was found that 7.8 moles of formaldehyde were methylol-bonded to one mole of 2,5-bis-(4,6-diamino-1,3,5-triazin-2-yl)-bicyclo[2.2.1]heptane. Example 15 Preparation of an N-methoxymethyl derivative of a diguanamine (1) Under reduced pressure, the N-methylol derivative of 5.0 g of the diguanamine (1), said derivative being a reaction mixture prepared in the same manner as in Example 10 and being formed of formaldehyde and the diguanamine bonded together at a molar ratio of 7.2:1, was dehydrated, followed by the addition of 50 mℓ of methanol. After being adjusted to pH 2.0 with a 20% nitric acid, the resulting mixture was heated at 40-45°C for 2 hours. The reaction mixture was adjusted to pH 8.0 with a 10% aqueous solution of sodium hydroxide. From the solution, methanol and water were removed under reduced pressure and then a solid was then filtered off, whereby a viscous liquid was obtained. As a result of an analysis of the liquid, it was found that 5.3 equivalents of N-methoxymethyl groups were bonded to one mole of the diguanamine (1). Example 16 Preparation of an N-methoxymethyl derivative of a diguanamine (2) Under reduced pressure, the N-methylol derivative of 5.0 g of the diguanamine (2), said derivative being a reaction mixture prepared in the same manner as in Example 11 and being formed of formaldehyde and the diguanamine bonded together at a molar ratio of 7.3:1, was dehydrated, followed by the addition of 50 mℓ of methanol. After being adjusted to pH 2.0 with a 20% nitric acid, the resulting mixture was heated at 40-45°C for 2 hours. The reaction mixture was adjusted to pH 8.0 with a 10% aqueous solution of sodium hydroxide. From the solution, methanol and water were removed under reduced pressure and a solid was then filtered off, whereby a viscous liquid was obtained. As a result of an analysis of the liquid, it was found that 4.9 equivalents of N-methoxymethyl groups were bonded to one mole of the diguanamine (2). As is understood from Examples 15 and 16, the N-methylol derivative of each diguanamine, said derivative pertaining to the present invention, readily undergoes an alkyl-etherification reaction with an alcohol under mild conditions, thus having excellent reactivity and can provide N-alkoxymethylated derivatives of the N-methylol derivative, said alkoxymethylated derivatives being extremely useful as resin intermediates. Example 17 Preparation of a primary condensate of N-methylol diguanamine (2) To 15.1 g (0.05 mole) of the diguanamine (2) obtained in the same manner as in Example 4, 13.1 g of paraformaldehyde (80% grade) (0.35 mole in terms of 100% formaldehyde) and 50 mℓ of methanol were added. The resulting solution was adjusted to pH 13.2 with a 20% aqueous solution of potassium hydroxide under stirring, followed by heating at 80°C for one hour under stirring. After the completion of the heating, the reaction mixture was adjusted to pH 8.0 with a 10% aqueous solution of hydrochloric acid. The resulting precipitate was filtered off, whereby a clear solution was obtained. As a result of an analysis of the resinous product obtained by the solvent removal of the clear solution, it was found to be a primary condensate of N-methylol diguanamine, said condensate being formed of the diguanamine (2) and formaldehyde methylol-bonded at a ratio of 6.0 moles of the latter to one structural unit of the former and having an average addition condensation degree of 1.3. Example 18 Preparation of a primary condensate of a diguanamine (1) To 15.7 g (0.05 mole) of the diguanamine (1) obtained in the same manner as in Example 1, 18.8 g of paraformaldehyde (80% grade) (0.5 mole in terms of 100% formaldehyde) and 50 mℓ of n-butanol were added. Under stirring, the solution was adjusted to pH 11.0 with a 10% aqueous solution of sodium hydroxide. The reaction mixture was heated at 60°C for 30 minutes under stirring, followed by the adjustment to pH 3.0 with a 20% aqueous solution of nitric acid. The reaction mixture was heated for 2 hours under reflux temperature conditions and stirring while being dehydrated. After the completion of the heating, the reaction mixture was adjusted to pH 8.0 with a 10% aqueous solution of sodium hydroxide. The resulting precipitate was filtered off, whereby a homogeneous and clear solution was obtained. As a result of an analysis of the resinous product obtained by the solvent removal of the solution, it was found to be a primary condensate of an etherified diguanamine formed of the diguanamine (1) and formaldehyde methylol-bonded at a ratio of 1.9 moles of the latter to one structural unit of the former, containing butyl ether groups and having an average addition condensation degree of 1.6. Example 19 Polymerization of an N-methylol derivative of a diguanamine and ultraviolet light resistance test of the resin so obtained In 10 mℓ of n-butyl alcohol, 5.0 g of an N-methylol derivative of the diguanamine (1), which had been obtained in the same manner as in Example 10 and was formed of the diguanamine (1) and formaldehyde bonded together at a ratio of 7.2 moles of the latter to one mole of the former, were dissolved, followed by the addition of 0.025 g of p-toluenesulfonic acid as a curing catalyst. The resulting solution was coated on a galvanized sheet steel and then, heated and cured at 140°C for 20 minutes. Using a germicidal lamp (manufactured by Toshiba Corporation; 19W) as an ultraviolet light source, the sheet steel so coated, that is, a test sheet steel, was exposed for 200 hours to ultraviolet light at a vertical distance of 25 cm. The surface gloss of the test sheet steel was measured in accordance with JIS K 5400 (specular reflection at 60°). As a result, the gloss retention was found to be 97%. Example 20 Polymerization of an N-methylol derivative of a diguanamine and ultraviolet light resistance test of the resin so obtained In 10 mℓ of n-butyl alcohol, 5.0 g of an N-methylol derivative of the diguanamine (2), which had been obtained in the same manner as in Example 11 and was formed of the diguanamine (2) and formaldehyde bonded together at a molar ratio of 7.3:1, were dissolved, followed by the addition of 0.025 g of p-toluenesulfonic acid as a curing catalyst. The resulting solution was coated on a galvanized sheet steel and then, heated and cured at 140°C for 20 minutes. Using a germicidal lamp (manufactured by Toshiba Corporation; 19W) as an ultraviolet light source, the sheet steel so coated, that is, a test sheet steel, was exposed for 200 hours to ultraviolet light at a vertical distance of 25 cm. The surface gloss of the test sheet steel was measured in accordance with JIS K 5400 (specular reflection at 60°). As a result, the gloss retention was found to be 98%. As has been shown in Examples 19 and 20, the N-methylol derivatives of diguanamines, said derivatives relating to the present invention, had excellent properties including superb polymerizability and an extremely small deterioration in gloss under ultraviolet rays. Example 21 Crease resistance test of a fiber treatment containing an N-methylol derivative of a diguanamine Deionized water was added to an N-methylol derivative of the diguanamine (1), which had been prepared in the same manner as in Example 10 and was formed of the diguanamine (1) and formaldehyde bonded together at a molar ratio of 7.2:1, to prepare its 10 wt.% aqueous solution. To the solution, 3 wt.% (relative to the solid content of the derivative) of ammonium secondary phosphate were added as a catalyst. A cotton cloth (cotton broadcloth No. 60) was dipped in the resulting solution, followed by padding. The cloth was subjected to preliminary drying at 80°C for 5 minutes and then, heated at 140°C for 5 minutes. A crease resistance test was conducted in accordance with JIS L 1059 (Monsanto method), using the cloth so treated. As a result, it was found that the cloth had a crease resistance of 86%, thus exhibiting excellent crease resistance. Each N-methylol derivative of a diguanamine, said derivative pertaining to the present invention, can impart, as demonstrated above, excellent crease resistance and the like to fibers when they are treated with the derivative. A thermosetting composition containing the diguanamine derivative therein is therefore extremely useful as a fiber treatment. Example 22 Curing test of a water-base paint resin containing an N-methylol derivative of a diguanamine To a solution obtained by gradually adding 1.84 g of dimethylethanolamine to 40.0 g of "Almatex WA 911" (product of Mitsui Toatsu Chemicals, Inc., NV: 60 %) under stirring and then adjusting its nonvolatile content to 20% with deionized water, a 50 wt.% aqueous solution of 6.0 g of an N-methylol derivative of the diguanamine (1), which had been prepared in the same manner as in Example 10 and was formed of formaldehyde and the diguanamine (1) bonded together at a molar ratio of 7.2:1, was added and mixed. The resulting resin solution so obtained was coated on a galvanized sheet steel and then, heated at 160°C for 20 minutes. On the coating film of the steel sheet so coated, cissing, blisters, discoloration or the like was not observed at all. The surface gloss of the coating film was measured in accordance with JIS K 5400 (specular reflection at 60°). As a result, the film was found to have a surface gloss of 98%, thus exhibiting outstanding smoothness and gloss. Furthermore, no peeling was observed on the film even after rubbing the film surface 50 times with an acetone-soaked cloth. It was, therefore, a fully cured and excellent coating film. Example 23 Curing test of a water-base paint resin containing an N-methylol derivative of a diguanamine To a solution obtained by gradually adding 1.84 g of dimethylethanolamine to 40.0 g of "Almatex WA 911" (product of Mitsui Toatsu Chemicals, Inc., NV: 60 %) under stirring and then adjusting its nonvolatile content to 20% with deionized water, a 50 wt.% aqueous solution of 5.9 g of an N-methylol derivative of the diguanamine (2), which had been prepared in the same manner as in Example 11 and was formed of formaldehyde and the diguanamine (2) bonded together at a molar ratio of 7.3:1, was added and mixed. The resulting resin solution so obtained was coated on a galvanized sheet steel and then, heated at 160°C for 20 minutes. On the coating film of the steel sheet, cissing, blisters, discoloration or the like was not observed at all. The surface gloss of the coating film was measured in accordance with JIS K 5400 (specular reflection at 60°). As a result, the film was found to have a surface gloss of 94%, thus exhibiting outstanding smoothness and gloss. Furthermore, no peeling was observed on the film even after rubbing the film surface 50 times with an acetone-soaked cloth. It was, therefore, a fully cured and excellent coating film. As has been demonstrated in Examples 21-23, each diguanamine derivative according to the present invention has excellent water reducibility and a thermosetting composition containing the derivative therein is not only excellent as a resin to be used in an aqueous system, such as a water-base paint resin, adhesive resin or fiber treatment but also exhibits excellent curing and crosslinking properties when used as a paint resin. It is therefore extremely useful for a wide variety of applications. Example 24 Curing test of a water-base paint resin containing an N-methoxymethyl derivative of a diguanamine To a solution obtained by gradually adding 1.84 g of dimethylethanolamine to 40.0 g of "Almatex WA 911" (product of Mitsui Toatsu Chemicals, Inc., NV: 60 %) under stirring and then adjusting its nonvolatile content to 20% with deionized water, a 50 wt.% solution of 6.8 g of an N-methoxymethyl derivative of the diguanamine (1), which had been prepared in the same manner as in Example 15 and was formed of formaldehyde and the diguanamine (1) bonded together at a molar ratio of 5.3:1, in a 50:50 (by weight) mixed solvent of butyl cellosolve and water as well as 0.15 g of p-toluenesulfonic acid were added and mixed. The resulting resin solution so obtained was coated on a galvanized sheet steel and then, heated at 160°C for 20 minutes. On the coating film of the steel sheet, cissing, blisters, discoloration or the like was not observed at all. The surface gloss of the film was measured in accordance with JIS K 5400 (specular reflection at 60°). As a result, the film was found to have a surface gloss of 96%, thus exhibiting outstanding smoothness and gloss. Furthermore, no peeling was observed on the film even after rubbing the film surface 50 times with an acetone-soaked cloth. It was, therefore, a fully cured and excellent coating film. As has been demonstrated above, each etherified diguanamine according to the present invention has excellent polymerizability and in addition, a thermosetting resin composition which contains the etherified diguanamine and a resin reactive therewith and therefore curable is extremely useful as a water-base paint resin. Example 25 Polymerization of an N-methoxymethylated diguanamine and a weathering test of the resin so obtained. In 10 g of methyl isobutyl ketone, 4.9 g of an N-methoxymethyl derivative of the diguanamine (2), which had been obtained in the same manner as in Example 16 and was formed of formaldehyde and the diguanamine (2) bonded together at a molar ratio of 4.9:1, were dissolved. To the resulting solution, 47.2 g of "Almatex P 646" (product of Mitsui Toatsu Chemicals, Inc., NV: 60%) were added and mixed. The resulting resin solution was coated on a galvanized sheet steel and then, cured by heating it at 180°C for 50 minutes. An exposure test of the sheet steel thus coated was conducted for 500 hours using a weather-o-meter. Neither blisters nor discoloration was observed on the surface of the coating film of the sheet steel. The surface gloss of the coating film was measured in accordance with JIS K 5400 (specular reflection at 60°). As a result, the gloss retention was found to be 95%. Example 26 Polymerization of a primary condensate of etherified diguanamine and a weathering test of the condensate so obtained. In 10 g of methyl isobutyl ketone, 5.0 g of a primary condensate of the etherified diguanamine (1), which had been obtained in the same manner as in Example 18 and had an average addition condensation degree of 1.6 per structural unit of the diguanamine (1) were dissolved. To the resulting solution, 47.2 g of "Almatex P 646" (product of Mitsui Toatsu Chemicals, Inc., NV: 60%) were added and mixed. The resulting resin solution was coated on a galvanized sheet steel and then, cured by heating it at 160°C for 30 minutes. An exposure test of the sheet steel thus coated was conducted for 500 hours using a weather-o-meter. Neither blisters nor discoloration was observed on the surface of the coating film of the sheet steel. The surface gloss of the coating film was measured in accordance with JIS K 5400 (specular reflection at 60°). As a result, the gloss retention was found to be 97%. As has been demonstrated in Examples 25 and 26, each of etherified diguanamines and these primary condensates according to the present invention have excellent polymerizability. In addition, a cured product obtained from a thermosetting resin composition containing therein the etherified derivative or the primary condensate and a resin curable through a reaction therewith has excellent weather resistance. It is, therefore, extremely useful as a paint resin. Example 27 Curing test of an epoxy-containing resin with a diguanamine (1) Dissolved in 100.0 g of butyl cellosolve were 100 g of an epoxy-containing resin ("Epicoat # 828"; product of Shell Kagaku K.K.). To the resulting solution, 19.6 g of the diguanamine (1) prepared in the same manner as in Example 1 were added and dissolved, whereby a resin solution was prepared. The resin solution was coated on a galvanized sheet steel, followed by heating at 110°C for 30 minutes and then, 200°C for 40 minutes. No peeling was observed on the coating film of the sheet steel so heated even after rubbing the film surface 50 times with a toluene-soaked cloth. It was a fully cured, transparent, excellent coating film. Example 28 Curing test of an epoxy-containing resin with a diguanamine (2) In a similar manner to Example 27 except that 18.9 g of the diguanamine (2) prepared in the same manner as in Example 3 were used instead of 19.6 g of the diguanamine (1) prepared in the same manner as in Example 1, a resin solution was prepared and a coating film curing test of the film was conducted. No peeling was observed on the coating film of the sheet steel so heated even after rubbing the film surface 50 times with a toluene-soaked cloth. It was a fully cured, transparent, excellent coating film. Example 29 Storage stability test of a thermosetting resin composition In each example, an epoxy-containing resin and the diguanamine shown in Table 3 were blended in the amounts indicated in the same table. The resulting blend was kneaded in a twin roll, which had been heated to 90-110°C in advance, for 15-30 minutes until the blend became fully uniform. The blend was taken out in the form of a sheet and then ground. The resulting sample was left over in a drier maintained at 40°C, whereby its storage stability was judged. The results are shown in Table 3. As can be seen from Table 3, each thermosetting resin composition according to the present invention has been found to have excellent storage stability. Epoxy-containing resin Diguanamine Storage stability at 40°C Kind Amount blended (parts by weight) kind Amount blended (parts by weight) Example 29-1 Epicoat #828 (Shell Kagaku K.K.) 100.0 Diguanamine (1) in Example 1 19.6 At least 3 months Example 29-2 Epicoat #828 (Shell Kagaku K.K.) 100.0 Diguanamine (2) in Example 4 18.9 At least 3 months Example 30 Flexibility test of a cured resin product obtained from a thermosetting resin composition Blended were 100 g of an epoxy-containing resin (''Epicoat # 828; product of Shell Kagaku K.K.) and 19.6 g of the diguanamine prepared in the same manner as in Example 1. They were kneaded in a twin roll, which had been heated at 90-110°C in advance, for 30 minutes until the blend became fully uniform. The blend was then taken out in the form of a sheet and then ground. The resulting sample was cured at 190°C for 3 hours to obtain a cured resin product. The Charpy impact resistance of the cured resin product was measured as an index for flexibility. The results are shown in Table 4. Incidentally, another cured resin product was produced as a comparative example under optimal curing conditions in a similar manner to the above except the dicyandiamide was used instead of the diguanamine in its optimum blending amount, and its Charpy impact resistance was measured. Amount of EP#828, an epoxy-containing resin, blended Amount of a diguanamine or dicyandiamide blended Curing conditions Charpy impact strength (kg·cm/cm 2 ) Example 30 100.0 g 19.6 g 190°C/3 hr 8.0 Comparative Example 3 100.0 g 5.5 g 170°C/1 hr 3.0 As is shown in Table 4, a cured resin product available from each thermosetting resin composition according to the present invention has been found to have excellent flexibility. Example 31 Weathering test of a cured coating film obtained from a thermosetting resin composition Dissolved in 200 g of butyl cellosolve were 100.0 g of an epoxy-containing resin ("Almatex PD # 7610"; product of Mitsui Toatsu Chemicals, Inc.; epoxy equivalent of solid: 530). The diguanamine (11.1 g) prepared in the same manner as in Example 1, was add to and dissolved in the resulting solution, whereby a resin solution was prepared. The resin solution was coated on a galvanized sheet steel and then heated and cured at 200°C for 40 minutes. A weathering test was conducted by exposing the sheet steel so coated to light for 300 hours under a weather-o-meter. The surface gloss of the coating film on the sheet steel was measured in accordance with JIS K 5400 (specular reflection at 60°). As a result, the gloss retention was found to be 94%. As has been demonstrated above, a cured resin product obtained from each thermosetting resin composition according to the present invention has been found to have excellent weatherability and is extremely useful as a paint resin. Example 32 Test on a coating film of a powder coating resin obtained from a thermosetting resin composition A resin solution of the thermosetting resin composition prepared in the same manner as in Example 31 was heated under reduced pressure to remove a solvent therefrom, whereby a resin was obtained in a solid form. The solid resin was coarsely ground in a coarse grinder, followed by fine grinding in an atomizer. The finely-ground particles so obtained were sifted through a 150-mesh sieve. Those passed through the sieve were employed for a test as a powder coating resin. The powder coating resin was coated on a bonderized sheet steel by electrostatic coating to give a film thickness of about 50 µm, and then heated at 200°C for 40 minutes. The coating film of the sheet steel so coated and heated was found to have good smoothness according to visual judgment. Furthermore, no peeling was observed on the film even after rubbing the film surface 50 times with a toluene-soaked cloth. It was a fully cured, excellent coating film. Using a germicidal lamp (manufactured by Toshiba Corporation; 19W) as an ultraviolet light source, the sheet steel so coated, that is, a test sheet steel was exposed for 200 hours to ultraviolet light at a vertical distance of 25 cm. Neither blisters nor discoloration was observed on the surface of the coating film of the sheet steel. The surface gloss of the test sheet steel was measured in accordance with JIS K 5400 (specular reflection at 60°). As a result, the gloss retention was found to be 96%. The coating film thus had excellent ultraviolet light resistance. Example 33 Adhesion test of a thermosetting resin composition Blended were 100 g of an epoxy-containing resin ("Epicoat # 828"; product of Shell Kagaku K.K.) and 15.7 g of the diguanamine (1) prepared in the same manner as in Example 1. They were kneaded in a twin roll, which had been heated to 90-110°C in advance, until they were fully and homogeneously mixed. Using the resin so kneaded, steel sheets were adhered. The resin was then cured at 200°C for one hour. The resin so cured was found to have a tensile shear adhesive strength of 176 kg/cm 2 at 25°C. As has been demonstrated above, each thermosetting resin composition according to the present invention has been found to have excellent adhesion and is extremely useful as an adhesive resin or the like. ADVANTAGEOUS EFFECTS OF THE INVENTION The diguanamines according to the present invention are useful for an extremely wide range of applications, because they are excellent in weatherability, ultraviolet light resistance and the like and can retain expected functions outdoors and the like over a long time; can provide methylol derivatives which have extremely good water reducibility; are substantially free of limitations as raw materials for resins used in water systems such as water-base paints and show excellent performance; have characteristic properties such that they contain active amino groups having extremely good reactivity with formaldehyde, epoxy compounds and the like and, owing to the inclusion of the eight active hydrogen atoms, permit selection of a methylol derivation degree from a wide range; and, in addition, can provide compounds, resins, compositions an the like which have excellent properties such as flexibility, toughness, high hardness, waterproofness and curability. Moreover, the process of the present invention for the preparation of such diguanamines is excellent because the target compound can be obtained in a high yield and with high purity while minimizing byproducts by reacting the specific dicarbonitrile, which is available economically, and dicyandiamide under specific conditions and the process including the purification step is simple. Such diguanamines have excellent polymerizability with various compounds such as aldehydes, epoxy compounds, carboxylic acids and isocyanates and also have various superb reactivity, so that the diguanamines are extremely useful as raw materials for resins and derivatives. They can provide, for example, derivatives extremely useful as curing agents and raw materials for various resins, such as N-methylol diguanamines obtained by reacting the diguanamines with aldehydes, etherified diguanamines, and their primary condensates; thermosetting compositions comprising these derivatives; and thermosetting resin compositions comprising the above diguanamines and epoxy-containing resins, said compositions being useful as paint resins and adhesive resins. The present invention is therefore excellent from the industrial standpoint.

Claims: A diguanamine represented by the following formula (1): wherein the bonding sites of the 4,6-diamino-1,3,5-triazin-2-yl groups are the 2,5- or 2,6-positions, or by the following formula (2) wherein the bonding sites of the 4,6-diamino-1,3,5-triazin-2-yl groups are the 1,2-, 1,3- or 1,4-positions. A process for the preparation of a diguanamine, which comprises reacting a dicarbonitrile, which is represented by the following formula (3): wherein the bonding sites of the cyano groups are the 2,5- or 2,6-positions, or by the following formula (4): wherein the bonding sites of the cyano groups are the 1,2-, 1,3- or 1,4-positions, with dicyandiamide in the presence of a basic catalyst. A process of claim 2, wherein the basic catalyst is at least one compound selected from the group consisting of alkali metals, alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal alcoholates, alkali metal salts of dicyandiamide, alkaline earth metal salts of dicyandiamide, amines and ammonia. A process of claim 2, wherein the reaction is conducted using as a reaction solvent at least one solvent selected from the group consisting of non-aqueous protonic solvents and aprotonic polar solvents. A process of claim 2, wherein the reaction is conducted in a temperature range of from 60°C to 200°C. An N-methylol diguanamine obtained by subjecting the diguanamine of claim 1 and an aldehyde to an addition reaction. An etherified diguanamine obtained by subjecting the N-methylol diguanamine of claim 6 and at least one alcohol selected from alcohols having 1-20 carbon atoms to etherification, said etherified diguanamine containing at least one R 1 OCH 2 group wherein R 1 represents a residual group formed by removing a hydroxyl group form the alcohol. A primary condensate of an N-methylol diguanamine obtained by subjecting the diguanamine of claim 1, a condensable compound as an optional reactant, and an aldehyde to addition condensation, having an average addition condensation degree greater than 1 and containing at least one methylol group. A primary condensate of an etherified diguanamine obtained by subjecting the diguanamine of claim 1, a condensable compound as an optional reactant and an aldehyde to an addition reaction or addition condensation reaction and then subjecting the reaction product and at least one alcohol selected from alcohols having 1-20 carbon atoms to etherification and optionally to simultaneous condensation, having an average addition condensation degree greater than 1 and containing at least one R 1 OCH 2 group wherein R 1 has the same meaning as defined above. A thermosetting composition comprising, as an essential component, at least one compound selected from the group consisting of the N-methylol diguanamine of claim 6, the etherified diguanamine of claim 7, the primary condensate of the N-methylol diguanamine of claim 8, and the primary condensate of the etherified diguanamine of claim 9. A thermosetting composition of claim 10, further comprising a resin curable through a reaction with the essential component as described in claim 10. A paint resin composition comprising the thermosetting composition of claim 11. A thermosetting resin composition comprising the diguanamine of claim 1 and an epoxy-containing resin. A paint resin composition comprising the thermosetting resin composition of claim 13. A paint resin composition of claim 14, which is a powder coating resin composition. An adhesive resin composition comprising the thermosetting resin composition of claim 13.

Inventors: INOMATA MASAMITU, KAMADA KAZUNORI, KARASAWA MINATO, MEGA IZUMI, NAKAHATA SHIGERU, NAKASHIMA TATSUNOBU, OISHI TETSUYA, OZAWA HIROSHI, SAKAMOTO KATSUMI, WATANABE AKITO, YAMAUCHI ATSUYOSHI, INOMATA, MASAMITU, KAMADA, KAZUNORI, KARASAWA, MINATO, MEGA, IZUMI, NAKAHATA, SHIGERU, NAKASHIMA, TATSUNOBU, OISHI, TETSUYA, OZAWA, HIROSHI, SAKAMOTO, KATSUMI, WATANABE, AKITO, YAMAUCHI, ATSUYOSHI
Applicants: MITSUI CHEMICALS INC, MITSUI CHEMICALS, INC.
Application year: 1993
Main classification: C07D251
IPC codes: C08G59, C08G12, C07D251