| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | February 3, 1987 |
| PATENT TITLE |
Modified phenolic resin composition |
| PATENT ABSTRACT | The present invention provides a resinous composition of modified phenolic compounds comprising a phenolic compound and an unsaturated cycloacetal, the composition being curable with an active energy rays, the improvement residing in the use of an onium salt. The cured material has no appreciable odor of acrolein and is stable in storage |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | July 19, 1985 |
| PATENT CLAIMS |
What we claim is: 1. A modified phenolic resinous composition curable with active energy rays comprising at least one phenolic compound selected from the group consisting of substituted or unsubstituted mononuclear phenol, bisnuclear phenol linked through a linking group, phenolic novolacs, and polyvinylphenols, at least one compound containing in one molecule at least two unsaturated cycloacetal radicals having the formula: ##STR4## wherein R represents hydrogen or a methyl group, and an onium salt selected from the group consisting of salts of diarylhalonium, triarylsulfonium and triarylselenium with tetraflourinated boron, hexafluorinated arsenic, hexafluorinated phosphorus, and hexafluorinated antimony. 2. The composition according to claim 1 wherein said unsaturated cycloacetal radical-containing compound is selected from pentaerythritoldiacroleinacetal, pentaerythritoldicrotonaldehydeacetal, cyclohexanonetetramethyloldiacroleineacetal, cyclohexanonetetramethyloldicrotoneacetal, and sorbitoltriacroleinacetal. 3. The composition according to claim 1 wherein the relative molar proportion of the unsaturated cycloacetal radical-containing compound to the mononuclear phenol is about 1.5 to 1. 4. The composition according to claim 1 wherein the relative weight proportion of the novolac to the unsaturated cycloacetalradical containing compound is about 80-130 part by weight of said compound to 100 parts by weight of said novolac. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
BACKGROUND OF THE INVENTION The present invention relates to a curable resinous composition of modified phenolic compounds and more particularly it relates to a resinous composition of modified phenolic compounds curable by active energy rays and comprising phenolic compounds, a compound having at least two unsaturated cycloacetal groups in its molecule as a cross-linking agent, and an onuim salt as an photoinitiator. DESCRIPTION OF THE PRIOR ART Reactions between a phenolic compound such as phenol, cresol, xylenol and resorcinol and formaldehyde produce reactive type resole resins or non-reactive type novolac resins. These novolac resins represent so-called two stage cure phenolic resins which cure by the addition of a curing agent such as hexamethylene teramine. Although the phenolic resins are historically the oldest resins having a variety of superior properties, they require heating, pressurizing or degassing due to the release of reaction by-products upon curing such as water, formaldehyde, lower nitrogen-containing compounds, or ammonia on the basis of their polycondensation reactions. They also have drawbacks of occluding the reaction by-products into the cured products. For remedying these drawbacks, Japanese Patent Publications Nos. 34-8138, 34-8139 and 34-8141, disclose one of the few known counter-measures, wherein a phenolic compound and a diallylidenepentaerythrytol, which is known as a condensation product of acrolein and a polyhydric alcohol such as pentaerythrytol, are cured in the presence of a strong acid catalyst such as paratoluenesulfonic acid. These methods, however, still have such drawbacks that upon curing, decomposition of the diallylidenepentaerythrytol concommitantly takes place thereby releasing aldehyde, i.e., acrolein having a strong irritating odor and that the stability of the resinous composition after formulation thereof is lower. Therefore, these resinous compositions have yet not been practically utilized. SUMMARY OF THE INVENTION The main object of the present invention resides in the provision of a resinous composition comprising phenolic compounds and unsaturated cyctoacetal compounds such as diallylidenepentaerythrytol capable of curing without any irritating odor of acrolein, thereby eliminating the drawbacks of the prior art. Thus the present invention is based on the discovery that a resinous composition comprising phenolic compounds unsaturated cycloacetal compounds such as diallylidenepentaerythritol system can be very rapidly photocured by the addition of an onium salt, which is a photocuring catalyst for curing a photo-curable composition comprising an unsaturated cycloacetal and polythiol (Japanese Patent Publication No. 57-33292), and which is selected from triarysulfonium, triarylselenium, and diarylhalonium with the result that there is very little irritating acrolein odor and no foaming takes place and that it has a superior shelf stability. The present invention relates to a modified phenolic resinous composition curable with an active energy rays comprising at least one phenolic compound, at least one compound containing in one molecule at least two unsaturated cycloacetal radicals having the formula: ##STR1## wherein R represents hydrogen or a methyl group, and an onium salt. More particularly, the present invention relates to an active energy radiation-curable modified phenolic resious composition comprising at least one phenolic compound selected from the group of a substituted or non-substituted mononuclear phenolic compound, dinuclear phenolic compound linked through a linking group, phenolic novolacs and polyvinyl phenolic compounds, at least one compound which contains substantially two or more unsaturated cyclo-acetal radicals in its molecule, as a cross-linking agent, the unsaturated cyclo-acetal radical being represented by the formula: ##STR2## wherein R represents hydrogen or a methyl group, and an onium salt as a photoinitiator selected from the group consisting of an onium salt selected from diarylhalonium, triarylsufonium, or triarylselenium salt of tetrafluoroboron, hexafluoroarsenic, hexafluorophosphorus or hexafluoroantimony respectively. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a chart of the infra-red spectrum of a mixture of diallydenepentaerythritol and phenolic novolac in a weight ratio of 50/50 to which was added 1.5% by weight of an photoinitiator, UVE-1014, sold by Gernal Electric Company, USA, FIG. 2 is a chart of the infra-red spectrum of the photo-cured product of FIG. 1, FIG. 3 is a chart of infra-red spectrum after thermally post-cured product of the photocured product of FIG. 2. DESCRIPTION OF THE PREFERRED EMBODIMENT The phenolic compounds employable herein include monohydric or polyhydric mononuclear phenolic compounds such as phenols, cresols, xylenols, resorcinols, and the like; dinuclear phenols resulting from linking phenolic compounds typified by phenols or cresols with a linking group, such as bisphenols derived from the condensation of the phenolic compounds with formaldehyde, its equivalent paraformaldehyde, or a ketone such as acetone in the presence of an acid catalyst; and novolac resins still having active hydrogen atoms in their phenolic nuclears. The novolac resins also include those having alkylphenols such as p-t-butylphenol, or phenylphenol as a portion of the novol composition. Polyvinyl phenol known as a polymer derived from p-vinyl phenol can also be employed similarly. Any mixture of these phenols can naturally be employed herein. The compounds having two or more unsaturated cycloacetal radicals employable herein are those disclosed in Japanese Patent Publication No. 57-33292 and typically prepared by the condensation of a polyol and an unsaturated aldehyde in the presence of an acid catalyst. Thus, the compounds can be obtained by condensing at an elevated temperature pentaerythritol and a molar excess of an unsaturated aldehyde such as acrolein or crotonaldehyde in the presence of a strong acid such as paratoluenesulfonic acid. After the condensation, the reaction mixture is neutralized, and then the excess aldehyde is driven off. Thereafter the condensation product is obtained by either of crystallization, distillation or extraction. The typical method for the production is described by Schulz et al. in the Angew. Chem. 62 105 (1950) and is incorporated herein by referring same. Among these unsaturated cycloacetal compounds, pentaerythritoldiacroleinacetal (diallydenepentaerythritol), pentaerythritoldicrotonaldehydeacetal (3.9-dipropenyl-2, 4, 8, 10-tetraoxasphiro-5.5-undecane), cyclohexanontetramethyloldiacroleinacetal, cyclohexanonetetramethyloldicro tonacetal, and sorbitoltriacroleinacetal are typical ones. The relative proportions of phenolic compounds and the unsaturated cycloacetal radical-containing compounds may be determined stoichiometrically in some degree. For example, if phenol, as a component for the phenolic compounds and diallylidene pentaerythritol, one of the most representative unsaturated cycloacetal compounds are used, 1.0 mol of phenol and about 1.5 mol of the latter are used. If bisphenol A is used, then 1 mol of bisphenol A is mixed with about 1 mol of diallylidenepentaerythritol to form the curable resinous composition. When polyvinylphenol or novolac is used, the relative proportion can be varied over a wide range depending upon the molecular weight of the polyvinylphenol or novolac or the object to be achieved. However, if common commercially available novolac is used, about 15 parts by weight of diallylidenepentaerythritol per 100 parts by weight of novolac can contribute to the gelling of the composition, while, 80-130 parts, preferably 100-130 parts by weight of diallylidenepentaerythritol per 100 parts by weight of novolac give a very hard, tough cured resin. For achieving the object of retaining flame-retandant property inherent to phenolnovolac, the proportion of diallylidenepentaerythritol is less, and for achieving toughness the latter may be used in relatively large amounts. In this way, the relative proportion can be determined in accordance with the stoichiometric handling of the average molecular weight of polyvinyl phenol and novolac. The scope of the present invention includes other compound or compounds in an amount not damaging the concept of the present invention. Thus, it is within the scope of the present invention to modify the composition by further adding polythiol employed in the above-mentioned Japanese Patent Publication in an amount smaller than the stoichiometric amount for the unsaturated cycloacetal thereby providing flexibility. It is also contemplated to add an epoxy resin for the dilution of the system or modification and further the incorporation of polymer compounds such as polyvinylbutyral or neoprene rubber is included within the scope of the present invention. It is also contemplated to incorporate a light-transmitting filler and/or fiber such as glass fibers. The photoinitiator, herein referred to is onium salts which have been described by Crivello et al. in the J. Poly. Sci. Sym. No. 56, pages 1-11. In the above literature, however, only the polymerization of cationically polymerizing compounds, for example, a polymerization of monomers such as .alpha.-methylstyrene, a vinylether and the like and a ring-opening polemerization of a ring compound such as trioxane, epoxides, acetals, lactones, and the like in the presence of the onium salt are reported, and no reference is made to the polymerization of unsaturated cycloacetals and phenols. Thus, this onium salt catalyst has been heretofore only noted as an good catalyst for a curing epoxy resin, especially for an cycloaliphatic epoxy compound. It is quite surprising to find that the curing of the mixture of phenols and unsaturated cycloacetals can proceed without releasing an irritating acrolein odor if the onium is used as the curing catalyst. The photoinitiator, i.e., photoinitiating cationic catalyst, is onium salts of diarylhalonium such as diaryliodinium, triarylsulfonium, triarylselenium of fluorinated boron, fluorinated arsenic, fluorinated phosphorus, fluorinated antimony, and the like. These onium salts are potential Lewis acid sources which generate Lewis acid upon absorption of active energy such as ultraviolet light. These include onium salts comprising dibenzeneiodinium, ditoluene iodinium, di-t-butylbenzeneiodinium, tribenzenesulfonium, tritoluenesulfonium, trimethoxybenzenesulfonium, tribenzeneselenium and the like of tetrafluoroboron, hexafluoroarsenic, hexafluorophosphorus, hexafluoroantimony, and the like. As these onium salts for photoinitiating an epoxy resin, triaryl sulfonium salt has recently become readily commercially available under the trade name of "UVE 1014" (General Electric Co.). Particular reference is made to these onium salts in a test entitled "UV Curing: Science and Technology", edited by S. Peter Pappas, and relevant descriptions from the text which are incorporated by refering it herein. The amount of these catalysts to be used is 0.1-5% by weight, more preferably 0.25-3% by weight of onium salt per 100 parts by weight of phenols plus the unsaturated cycloacetal. The resinous composition of the present invention can be gelled or cured by irradiating active energy rays such as those obtainable from a UV generation apparatus such as a medium to high pressure mercury lamps. However, it is preferable, contray to the conventional polymerization of epoxides alone or a polymerization of vinylether, to perform a post thermal curing for a short period of time, without relying on the radiant heat from the UV lamp, in combination with the photo-irradiation in which the onium salts effectively generate a source of Lewis acid as a catalyst for the addition reaction between phenolic compounds and the unsaturated cycloacetal compounds under photoirradiation. It may be possible to add a photochemical sensitizer such as acridine orange as set forth in J. POLY. SCI. CHEM. 16, 2441 (1979). The composition of the cured material of the curable modified phenolic resinous composition according to the present invention is not yet precisely understood, but it is thought that a cross-linking reaction based on the reaction between the active hydrogens on the benzene ring of phenolic compounds and the unsaturated groups of the unasaturated cycloacetal compounds takes place because according to the above-mentioned Japanese Patent Publication No. 34-8138, or a bisphenol is synthesized containing spiro (m-dioxane) from a largle excess of phenol and diallylidenepentaerythritol. However, upon photo-curing of the composition according to the present invention it may be expected that ring opening of the diallylidenepentaerythritol, a six-membered ring, may partly happen, because as we already published that a ring opening of diallylidenepentaerythritol or unsaturated cyclooxoranacetal is observed in the presence of a free radical-generating catalyst or under the irradiation of radiation (see the journal "Shikizai" 53[3]140-145(1980), & Japan Adhesive Association Kanto Branch 1978, December Regular Meeting as to the former and "MACROCHEMIE"95(1966) 168-178, Furukawa, et al. about the latter). Thus, the reactions between the phenols and the unsaturated cycleacetals is modeled as follows, taking phenol novolac as the phenols and the unsaturated cycleacetals is modeled as follows, taking phenol novolac as the phenols and diallylidenepentaerythritol as the unsaturated cyclo-acetals: ##STR3## FIG. 1 is a chart of infra-red spectrum analysis of a composition comprising phenol novolac and diallylidenepentaerythritol in a weight ratio of 50/50 to which is added 1.5% by weight of an photoinitiator, UVE-1014. FIG. 2 is a chart of infra-red spectrum analysis after photo-curing and FIG. 3 is a chart of infra-red spectrum analysis after subsequent post heat-curing, in which the peak of 1720 cm.sup.-1 represents the obsorption of carbonyl in ester, and the peaks at 1470 cm.sup.-1 and 880M.sup.-1 are absorption due to tetra-substituted benzene nucleaus. Upon ignition of the cured resin, generally a sever irritation occurs if the unreacted diallylidenepentaerythritol remains. However, the cured resin of the present invention does not give an appreciable irritation due to acrolein, and thus it is thought that hydrallylidenepentaerythritol almost entirely participates in resin formation. The resinous compositions according to the present invention are useful for the preparation of coatings, adhesive materials, inks, and reinformed laminates. |
| PATENT EXAMPLES | available on request |
| PATENT PHOTOCOPY | available on request |
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