JPH0251924B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a curing agent for epoxy resin, and more specifically, to a curing agent for epoxy resin that provides a cured epoxy resin having a high glass transition point. [Prior art and its problems] Various compounds have been known as curing agents for epoxy resins, but maleic anhydride has been widely used as a curing agent because relatively mild conditions can be adopted. Acids and phthalic anhydride are known. However, the epoxy resin cured products obtained using these curing agents have a glass transition point of 120~
Due to the low temperature of 170°C, the uses of epoxy resins were often limited. Furthermore, pyromellitic anhydride is known as a curing agent used for the purpose of obtaining a cured epoxy resin product having a high glass transition point. However, this pyromellitic anhydride has a high melting point of 286°C, which is much different from the normal curing temperature of epoxy resin (nearly 170°C), so the phase between unmelted pyromellitic anhydride and uncured epoxy resin is high. Currently, it has very poor solubility and is hardly used in practice. For this reason, attempts have been made to mix maleic anhydride or phthalic anhydride with this pyromellitic anhydride to form a curing agent. However, in order to harmonize the melting point of the curing agent and the curing temperature of the epoxy resin, a complicated mixing operation of the pyromellitic anhydride and the maleic anhydride or phthalic anhydride is required, and it is not always possible to obtain a uniform mixture. Not necessarily. Furthermore, since pyromellitic anhydride has extremely high hygroscopicity, more care than expected must be taken in the production and handling of curing agents containing pyromellitic anhydride. This invention was made based on the above circumstances, and the glass transition point of the cured epoxy resin is
It is an object of the present invention to provide a curing agent for epoxy resin that can be easily handled and that can obtain a cured epoxy resin product at a temperature exceeding 200°C. [Means for solving the above problems] In order to solve the above problems, the present inventors conducted intensive research and surprisingly found that known polymer compounds are suitable as curing agents for epoxy resins.
Moreover, the present invention was achieved by discovering that the polymer compound is easy to manufacture and handle. The outline of this invention is a curing agent for epoxy resin characterized by having a reaction product obtained by a polymerization reaction of dicyclopentadiene and maleic anhydride. The dicyclopentadiene and maleic anhydride themselves are known compounds, and there are no particular limitations on the two compounds in this invention. However, it is preferable that both dicyclopentadiene and maleic anhydride be sufficiently purified prior to the polymerization reaction. When unpurified dicyclopentadiene and maleic anhydride are polymerized,
Side reactions may occur and it may not be possible to obtain a suitable reaction product. The above reaction product is obtained by a known copolymerization reaction between dicyclopentadiene and maleic anhydride, and although this reaction product can be obtained by a known copolymerization reaction, its structure is still unknown. Although there is no established theory, it is presumed to be a copolymer of dicyclopentadiene and maleic anhydride, but it is also possible that it is a copolymer of cyclopentadiene produced by thermal decomposition of dicyclopentadiene. The reaction product may also contain dicyclopentadiene or a cyclopentadiene homopolymer. However, in order to make the reaction product suitable as a curing agent for the epoxy resin of the present invention, for example, the number average molecular weight of this reaction product must be
It is preferably 300-5000, especially 500-2000,
Further, it is preferable that the maleic anhydride component in this reaction product is contained in an acid value of 50 to 700, particularly 100 to 500. As the polymerization reaction conditions for producing a reaction product suitable as described above as a curing agent for this epoxy resin, for example, the temperature at which dicyclopentadiene and maleic anhydride are heated is 200 to 300°C, particularly preferably 250°C. ~280°C, and the polymerization reaction time is 0.5 to 12 hours, particularly preferably 3 to 5 hours. Incidentally, a solvent is not necessarily required in the copolymerization reaction, and when a solvent is used for controlling the reaction temperature, dispersing monomers, etc., it is preferable to use, for example, benzene, toluene, xylene, etc. Further, this copolymerization reaction does not particularly require a catalyst. In the curing agent for epoxy resin according to the present invention, when a solvent is not used during copolymerization, the reaction product obtained by polymerizing the dicyclopentadiene and maleic anhydride and removing unreacted monomers can be used as is. can. A cured epoxy resin product can be obtained by mixing this reaction product with an uncured epoxy resin and setting predetermined curing conditions. The uncured epoxy resin can be arbitrarily selected from known ones having at least two epoxy groups per molecule, such as brominated epoxy resin, epoxy novolac resin, bisphenol A-epichlorohydrin. Resins, polyfunctional epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, etc. can be used. A typical example of these epoxy resins is a resin obtained by the reaction of bisphenol and epichlorohydrin, and is represented by the following general formula, (In the formula, n is 0 or an integer of 10 or less.) Generally, n is 2 or 3 or less, and the epoxy equivalent is 170
~300 is preferred. Furthermore, diluents such as glycidyl ethers of aliphatic alcohols having 3 to 10 carbon atoms, such as butyl glycidyl ether, allyl glycidyl ether, and other commercially available epoxy diluents can also be added to these epoxy resins. The diluent is usually 20% of the epoxy resin.
It can be used in an amount of not more than parts by weight. During curing, the proportion of uncured epoxy resin and this reaction product is usually 50 to 200 parts by weight per 100 parts by weight of the epoxy resin.
Parts by weight, particularly preferably 80 to 130 parts by weight. The curing conditions are, for example, 1 at a temperature of 100 to 200°C.
Examples include heating for ~3 hours. Furthermore, during curing, a curing accelerator such as tris(dimethylaminomethyl)phenol, triethylamine, diethylamine, ethanolamine, etc. may be added. The epoxy resin cured product obtained by the curing reaction has a glass transition point of 200℃ or higher, so
It is suitably used as a material for baking paints, adhesives, sealing members for various parts of electronic devices, printed wiring boards, etc., which require good thermal properties such as thermal shock resistance. [Effects] In this invention, a single reaction product obtained by the copolymerization reaction of dicyclopentadiene and maleic anhydride is used for the first time as a curing agent for epoxy resin, and it is easy to manufacture and handle. When uncured epoxy resin is cured with an epoxy resin curing agent, the glass transition point is 200.
It is possible to obtain a cured epoxy resin having excellent thermal shock resistance at a temperature of at least .degree. The curing agent for epoxy resins of the present invention can also provide cured epoxy resins suitable for electronic parts, paints, and adhesives that require thermal shock resistance. [Example] Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Examples 1-3 150g of dicyclopentadiene and maleic anhydride
150 g and 90 g of xylene were charged into a 1 liter autoclave, and a copolymerization reaction was carried out at 260° C. for 3 hours in a nitrogen atmosphere. After the reaction was completed, xylene and unreacted substances were removed under reduced pressure to obtain 288 g of a reaction product. The number average molecular weight of this reaction product was 1450, and the acid value was 466. Next, 100 parts by weight of a bisphenol type liquid epoxy resin [trade name: Epicote 828, manufactured by Ciel Kagaku Co., Ltd.], the reaction product in the proportions shown in Table 1, and tris (dimethylaminomethyl) as a curing accelerator were added. Mix with phenol and heat at 170℃ for 2 hours.
A curing reaction was performed to obtain a cured product for epoxy resin. Regarding this cured product for epoxy resin, JIS K6911
Measure bending strength and bending modulus in accordance with
The glass transition point was measured by dynamic viscoelasticity measurement. The results are shown in Table 1. Comparative Examples 1 and 2 The same procedure as in the above Examples was carried out except that the same epoxy resin used in Examples 1 to 3 and the curing agent of the type and amount shown in Table 1 were mixed. The results are shown in Table 1. Incidentally, even if the amount of curing agent added was greater than the amount shown in Table 1, no effect was obtained.

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Claims (1)

[Scope of Claims] 1. A curing agent for epoxy resin characterized by comprising a reaction product obtained by a polymerization reaction of dicyclopentadiene and maleic anhydride. 2 The reaction product has a number average molecular weight of 300 to
5000, and its acid value is 50-700.