JPS6228970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermosetting resin composition containing an epoxy resin, a regenerated cyanate product, and an oxazoline ring forming catalyst as essential components, which provides a cured product with excellent storage stability and excellent heat resistance. . Recently, it has been known that by reacting a polyfunctional bismaleimide-triazine resin (hereinafter referred to as BT resin) with an epoxy resin to form an oxazoline ring, a cured product with extremely excellent heat resistance can be obtained, and it is widely used. It is beginning to be used for various purposes. However, as is well known, cyanate group (R
-OCN) is a highly reactive functional group equivalent to an isocyanate group (R-NCO), so BT before forming an oxazoline ring to form a cured product.
When storing a liquid resin composition of resin and epoxy resin, if it is not stored in a sealed state, the cyanate groups will react with moisture in the atmosphere and the resin composition will deteriorate in a short period of time, resulting in poor storage stability. It had the disadvantage of being extremely poor at sex. The present inventors have conducted extensive research to overcome the drawbacks of the prior art described above and provide a resin composition consisting of BT resin and epoxy resin that has excellent storage stability and heat resistance. Using a regenerated cyanate obtained by protecting the functional groups (cyanate groups) of BT resin with a masking agent,
When a composition is prepared by curing this and an epoxy resin in the presence of an oxazoline ring-forming catalyst, a cured product that does not react with moisture in the atmosphere, has excellent storage stability, and has good heat resistance can be obtained. The present inventors have discovered that a resin composition can be obtained, and have completed the present invention. That is, the present invention provides a protected general formula () by adding 2.0 to 3.5 equivalents of a masking agent to 1 equivalent of cyanate group of epoxy resin and BT resin having two or more epoxy groups in the molecule: (In the formula, R is an organic group, X is a residue of XH representing a phenol, alcohol, or secondary amine as a masking agent, and n is the same number as the cyanate group in the bismaleimide-triazine resin) The essential ingredient is a polymerizable cyanate regenerated product.
The object of the present invention is to provide a thermosetting resin composition in which 0.4 to 2 equivalents of cyanate regenerant are blended with respect to 1 equivalent of the epoxy resin, and an oxazoline ring forming catalyst is further blended. General formula () used in the present invention: (In the formula, R is an organic group, X is a residue of XH representing a phenol, alcohol, or secondary amine as a masking agent, and n is the same number as the cyanate group in the BT resin) Since it does not have cyanate groups, it does not react with moisture and has excellent storage stability, and when heated, it dissociates and regenerates cyanate groups as shown in the following formula. Phenols, alcohols, or secondary amines, which are masking agents for protecting the cyanate groups of BT resin, dissociate from the regenerated cyanate product when heated, and volatilize from the resin composition after dissociation. Of these, phenols such as phenol and cresol are preferred. Further, the appropriate amount to be used is 2.0 to 3.5 equivalents per equivalent of BT resin. If the amount used is less than 2.0 equivalents, the effect of using the masking agent will not be sufficiently exhibited, and voids will be likely to occur in the process of heating and curing a resin composition that is estimated to have more than 3.5 equivalents, both of which are unfavorable. On the other hand, the BT resin protected by a masking agent is a resin obtained by modifying bismaleimide having a diphenylmethane skeleton and a triazine resin having a bisphenol A skeleton, and a resin having a cyanate equivalent of 150 to 350 is used. Preferably used.
Typical examples are BT-2170, BT-2400, BT
-2600 (all product names, manufactured by Mitsubishi Gas Chemical Co., Ltd.). Examples of the epoxy resin having two or more epoxy groups in the molecule used in the present invention include commercially available epoxy resins having an epoxy equivalent of about 150 to 1500, such as bisphenol A-based epoxy resin, novolac-based epoxy resin, and cyclo-based epoxy resin. can be given. Preferred representative examples include Epon 827, Epon 828, Epon 1001 (all trade names, bisphenol A epoxy resins manufactured by Yuka Shell Co., Ltd.), and DER-332 (trade name, bisphenol A manufactured by Dow Chemical Company). epoxy resin), DEN-431, DEN-438 (all product names,
Novolak epoxy resin manufactured by Dow Chemical Company), CY-179 (trade name, cyclo epoxy resin manufactured by Ciba Geigy), etc. In the present invention, the epoxy resin and the regenerated cyanate are essential components, and the regenerated cyanate is blended in an amount of 0.4 to 2 equivalents per equivalent of the epoxy resin. If the blending ratio is less than 0.4 equivalents, sufficient crosslinking will not be possible and the resulting cured product will be insufficiently cured.On the other hand, if the blending ratio exceeds 2 equivalents, the mechanical properties of the cured product will be markedly deteriorated. Undesirable. The composition of the invention can be prepared, for example, in advance.
This can be done by mixing a recycled cyanate obtained by reacting a BT resin with a masking agent with an epoxy resin at a blending ratio depending on the purpose, or an epoxy resin may be added to the recycled cyanate.
The preparation method is not limited to these. The composition of the present invention is heat-cured using an oxazoline ring-forming catalyst, and the catalyst may be added during the preparation of the composition of the present invention or during curing treatment. Oxazoline ring formation catalysts that can be used include, for example, acetylacetone and Al, Ba, Cd, Cu, Cr, Fe, Mg, Mn,
Examples include metal carbonyl compounds made of divalent or trivalent metals such as Ni, Pb, and Zn. The amount of the oxazoline ring forming catalyst added is 0.05 to 5% to the mixture of the epoxy resin and cyanate regenerated product.
(% by weight, the same applies hereinafter) is appropriate. If the amount added is outside the range of 0.05 to 5%, the oxazoline ring may not be sufficiently formed, or the heat resistance of the resulting cured product may tend to deteriorate. The thermosetting resin composition of the present invention has excellent storage stability, and in the presence of an oxazoline ring formation catalyst,
It is easily cured by heating at 100 to 220℃ for 1 to 40 hours, and the resulting cured product can be heated at high temperatures (for example, 230℃).
It can be used continuously for a long period of time and has excellent heat resistance. Furthermore, the resulting cured product has excellent electrical and mechanical properties, so it has a wide range of uses, including heat-resistant insulating varnish, impregnating resin, and resin for laminated boards. The excellent properties of the resulting cured product include the formation of an oxazoline ring (heat resistance), the coexistence of the BT resin part with high crosslink density and the relatively flexible epoxy resin part in an appropriate balance (electrical, mechanical properties). Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples. Note that the present invention is not limited to these examples. Example 1 50g of BT resin (BT-2170) with cyanate equivalent of 200
60g (2.2 equivalents) of m-cresol as a masking agent
38g of epoxy resin (CY-179) with an epoxy equivalent of 152 and 2.5g of Mn() acetylacetonate were added to the cyanate regenerated product obtained by heating at 60°C for 2 hours to form a resin composition (cyanate regenerated product). Equivalent: 1 Epoxy resin equivalent (hereinafter abbreviated as BT/EP): 1) was prepared. The obtained composition was heated and cured, and the obtained cured product was cured at 100℃ for 4 hours to examine its heat resistance.
The composition was then heated and cured at 220°C for 12 hours, and the weight loss onset temperature of the cured product was measured in a nitrogen atmosphere.The weight loss initiation temperature did not reach 340°C, and it showed excellent heat resistance. In addition, when the resin composition obtained between 25 mm square iron blocks was uniformly applied, both coated surfaces were bonded and cured under the same conditions as above, and the adhesive strength was measured, it was 250 kg/cm ² (5 pieces average value), which was very good. Furthermore, in order to investigate the storage stability of the resulting resin composition, the composition was left in a room at 25°C and 80% humidity for two months, and its appearance and adhesive strength were examined, and there was no change in appearance. The adhesive strength (under the same conditions as above) was 245 Kg/cm ² , showing almost no change. The above results are shown in Table 1. Example 2 25g of BT-2170, DEN- as epoxy resin
431 (epoxy equivalent 175) 55g, m-cresol
A resin composition (BT/EP: 0.4) was prepared in the same manner as in Example 1 except that 35 g (2.6 equivalents) was used, and its properties were investigated, and it was found to be as excellent as in Example 1. The results are shown in Table 1. Example 3 A resin composition (BT/EP: When Example 2) was prepared and its properties were investigated, it was found to be as excellent as Example 1. The results are shown in Table 1. Example 4 Example 1 except that 57.5 g of BT-2400 with a cyanate equivalent of 230, 38 g of CY-179 with an epoxy equivalent of 152, and 69 g (2.9 equivalents) of phenol as a masking agent were used.
A resin composition (BT/EP: 1.0) was prepared in the same manner as in Example 1, and its properties were examined and found to be as excellent as in Example 1. The results are shown in Table 1. Example 5 50g of BT-2600 with cyanate equivalent of 250, CY-
A resin composition (BT/
EP: 0.8) was prepared and its properties were investigated, and it was found to be as excellent as in Example 1. The results are shown in Table 1. Comparative example 1 34.5g of BT-2400, 19g of Epicote 828, Cr
(2) A resin composition (BT/EP: 1.5) was prepared by using 5 g of acetylacetonate and mixed uniformly, and the adhesive strength was 250 kg when heat bonded using this under the same conditions as in Example 1. / ^cm2 , but in terms of storage stability, the resin composition deteriorated into a gel-like state after 7 days from preparation, and even if this modified resin composition was used for bonding under the same conditions as above, it could no longer be bonded. No strength was shown. The results are shown in Table 1. Example 6 20g of resin composition prepared in the same manner as Comparative Example 1
11.2 g (2.1 equivalents) of phenol as a masking agent was added to the resin composition, dissolved and stored in a sealed state at room temperature for one day.The properties of the resin composition were investigated and found to be as excellent as in Example 1. The results are shown in Table 1. Comparative Example 2 20g of resin composition prepared in the same manner as Comparative Example 1
When 40 g (7.5 equivalents) of phenol was added as a masking agent to the resin composition, the resin composition was dissolved and stored in a sealed state at room temperature for 1 day, and the adhesive strength was measured.
Voids were generated during the curing process, and the adhesive strength was very low. The results are shown in Table 1. Comparative example 3 8g of BT-2170, DER- as epoxy resin
332 (epoxy equivalent: 175) 35g, phenol 6g
A resin composition (BT/EP: 0.2) was prepared in the same manner as in Example 1 except that (1.6 equivalents) was used, and the heat resistance and adhesive strength of the resulting resin composition were examined. Equivalence ratio with BT resin (BT/
EP) was less than 0.4, oxazoline rings were not sufficiently formed, and both heat resistance and adhesive strength were very poor. In addition, regarding storage stability, the effect of adding a masking agent was not apparent because the amount of the masking agent was less than 2.0 equivalents, and therefore, 7 days after preparation, the resin composition changed into a gel-like state and no longer had adhesive ability. .
The results are shown in Table 1. Comparative Example 4 Example 1 except that 50 g of BT-2170, 17.5 g of DER-332, and 40 g (1.48 equivalents) of m-cresol were used.
A resin composition (BT/EP: 2.5) was prepared in the same manner as above, and its properties were investigated. As BT/EP exceeded 2.0, unreacted cyanate groups were present, and the heat resistance and adhesive strength were very poor. It was hot. Regarding storage stability, as in Comparative Example 3, since the amount of masking agent used was less than 2.0 equivalents, the product changed into a gel-like state 7 days after preparation. Results first
Shown in the table. Comparative Example 5 760 g of Epicote 828 and 250 g of 4,4'-diphenylmethane diisocyanate were mixed, and 0.6 g of tetraethylammonium bromide was used as a catalyst.
After reacting at 150° C. for 3 hours to produce an isocyanate-modified epoxy resin having an oxazoline ring and an isocyanurate ring and solid at room temperature, dioxane was added to prepare a solution with a solid content of 50%. On the other hand, 557 g of 2,2-bis(4'-cyanatophenyl)propane, which is a cyanate ester compound of bisphenol A, and N,N'-(oxydi-p-
(phenylene) bismaleimide 721g and N,N-
Add to 1278 g of dimethylformamide, heat to 80°C to dissolve uniformly, then add 0.5 g of 2-ethyl-4-methylimidazole and heat and stir for 2 hours.
A prepolymer solution was prepared. 1,800 g of the prepolymer solution and 1,200 g of the dioxane solution of the isocyanate-modified epoxy resin were mixed, 7 g of Co() acetylacetonate was added, and the mixture was thoroughly stirred and dissolved to obtain a uniform resin solution. Using the resulting resin solution with the solvent removed, a sample was prepared and evaluated in the same manner as in Example 1. The heat resistance was 360°C and the adhesive strength was 273 Kg/ ^cm2 , which were good. As for the storage stability, which was measured in the same manner as in Example 1, the appearance changed to gel-like, and the adhesive strength could not be determined. From the above-mentioned Examples and Comparative Examples, resin compositions having free cyanate groups as in the prior art have poor storage stability when stored in an open state.
On the other hand, it has become clear that if a regenerated cyanate product is used as in the present invention, it will not react with moisture in the atmosphere at all even if it is not stored in a sealed state. In addition, the cured product obtained has very good heat resistance, so the thermosetting resin composition of the present invention is of great industrial value. 【table】

Claims (1)

[Claims] 1. 2.0 to 3.5 of the masking agent per equivalent of cyanate group in epoxy resins and bismaleimide-triazine resins having two or more epoxy groups in the molecule.
Equivalent plus protected general formula (): (In the formula, R is an organic group, X is a residue of XH representing a phenol, alcohol, or secondary amine as a masking agent, and n is the same number as the cyanate group in the bismaleimide-triazine resin) The regenerated cyanate is an essential component, and the regenerated cyanate is 0.4 to 2 per equivalent of the epoxy resin.
A thermosetting resin composition in which an equivalent amount of an oxazoline ring forming catalyst is further blended. 2. The composition according to claim 1, wherein the oxazoline ring forming catalyst is blended in an amount of 0.05 to 5% by weight based on the mixture of the epoxy resin and the regenerated cyanate product. 3 The epoxy equivalent of the epoxy resin is 150~
1500. The composition according to claim 1 or 2, wherein the composition is 4. Claim 1, wherein the epoxy resin is a bisphenol A-based epoxy resin, a novolac-based epoxy resin, or a cyclo-based epoxy resin,
The composition according to item 2 or 3. 5. The composition according to claim 1 or 2, wherein the bismaleimide-triazine resin has a cyanate equivalent of 150 to 350. 6. The composition according to claim 2, characterized in that a metal carbonyl compound is used as the oxazoline ring forming catalyst.