JPH0410899B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an epoxy resin composition that provides a cured product that is colorless and transparent and does not change color for a long period of time. [Prior Art] By combining epoxy resins with various curing agents, cured products with excellent performance can be obtained. In other words, epoxy resin compositions have excellent heat resistance, water resistance, chemical resistance, electrical properties, mechanical strength, dimensional stability, flexibility, etc., and are therefore useful for paints, adhesives, electrical equipment materials, etc.
It is widely used industrially in laminated products, molded products, structural materials, fiber processing agents, etc. Recently, it has been proposed that its properties can be used for optical purposes such as manufacturing optical lenses, prisms, etc., and sealing light emitting diodes, etc. In this case, it is particularly important to avoid coloring of cured products over time and devitrification phenomena. Improvements are required. Conventional solutions to this problem include methods using epoxy resins, organic acid anhydride curing agents, and tertiary amines or their organic acid salts as curing accelerators, organic phosphites, hindered phenols, bluing agents, etc. Although a method of adding , etc., has been proposed, the results were still unsatisfactory. Furthermore, as a method for improving these, a method of adding an organic phosphorus compound represented by the following formula (A) or (B) has been proposed (Japanese Patent Laid-Open No. 57-205418). [In the formula, R ₁ to _{R 8} are hydrogen, halogen, or carbon number 1
~10 monovalent aliphatic or aromatic substituents,
R ₁ to R ₈ may be the same or different. [Problems to be Solved by the Invention] According to the study results of the present inventors, the above-mentioned proposed method is more effective in preventing discoloration of epoxy resin compositions and cured products obtained therefrom than in conventional known techniques. Although they are excellent in effectiveness, the organic phosphorus compounds represented by formulas (A) and (B) have problems in compatibility with each component of the epoxy resin composition and the composition, and are inconvenient in blending operations. Furthermore, when epoxy resin compositions are used in the optical field, further improvement in the coloring prevention effect has been desired. [Means for Solving the Problems] The present inventor has made extensive studies in response to such requests for improvement, and has arrived at the present invention. That is, the present invention provides an epoxy resin composition consisting essentially of (a) an epoxy resin, (b) an organic polybasic acid anhydride, and (c) a curing accelerator, [In the formula, R ₁ and R ₂ each independently represent a halogen atom, an alkyl group, an aryl group, or an aralkyl group that may optionally be substituted with a halogen atom or an alkyl group, and x and y are 0 or 1
an integer of ~3, R ₃ is the residue excluding the hydroxyl group of an organic compound having m hydroxyl groups,
And m represents an integer of 1 to 10, preferably 1 to 6, more preferably 1 to 4. however,
When m is 1, _R3 is a _C8 - _C20 alkyl group or an aryl group substituted at least at the 2-position with a tertiary alkyl group. ] An epoxy resin composition characterized in that the organic phosphorus compound represented by the formula is contained in an amount of 0.1 to 20% by weight based on the total amount of components (a) to (c). The resin composition of the present invention is extremely effective in preventing discoloration and deterioration of transparency during storage, molding, and long-term aging of the molded product, and
The above-mentioned organophosphorus compounds have good compatibility with resin compositions and their constituent components, and therefore operations such as blending, processing, and molding are easy, and molded products of uniform and good quality can be obtained, and they can be used for various purposes. It is extremely advantageous in applications, especially when used for optical system purposes. The organic phosphorus compound represented by the general formula () is produced according to the method described in Japanese Patent Publication No. 49-45397. That is, a compound of formula () is obtained by reacting a hydroxy group-containing organic compound with a compound of formula () obtained by reacting an o-phenylphenol compound of formula () with phosphorus trichloride. It will be done. If R ₃ − (OH) _n is a low molecular weight (low boiling point) monohydric alcohol or phenol, it can be produced directly according to the above reaction formula, but R ₃ − (OH) _n is relatively high. In the case of molecular weight or polyhydric hydroxy compounds, the compound of formula () is first reacted with an appropriate monovalent hydroxy compound, preferably phenol, to obtain the compound of formula (), and then R ₃ −(OH ) A compound of formula () is advantageously obtained by adding a hydroxy compound of _n and heating to carry out an exchange reaction with phenol. [In each of the above reaction formulas, R ₁ , R ₂ , R ₃ , x, y and m
is the same as the definition in formula () above. ] For example, the following organic phosphorus compounds can be obtained by the above method. {However, if x=y=0, the symbol in brackets after the structural formula is its abbreviation} (1) From 1 mole of formula () and 1 mole of decyl alcohol (2) 2 moles of formula () and 1,1-bis(4-hydroxy-2-methyl-5-t-butylphenyl)
From 1 mole of butane (3) From 1 mole of formula () and 1 mole of 2,4-di-t-butylphenol (4) From 1 mol of formula () and 1 mol of 2-t-butyl-4-cresol (5) From 2 moles of formula () and 1 mole of 2,5-di-t-butylhydroquinone These organic phosphorus compounds should be added at 0.1% relative to the total amount of epoxy resin, polybasic acid anhydride, and curing accelerator.
~20% by weight, preferably 0.3-5%, especially 0.5-1.5%
It has very good compatibility. Known epoxy resins are used as the epoxy resin in the present invention, but colorless or light-colored ones are suitable, particularly in view of the characteristics of the effects of the present invention. Typical epoxy resins include bisphenol type resins obtained from bisphenol A, bisphenol F, etc. and epichlorohydrin;
Cycloaliphatic type, tetra or hexa-
Examples include polyglycidyl ester types of polybasic acids such as hydrophthalic acid, and polyglycidyl ether types of phenol novolaks and long-chain polyols. Examples of organic polybasic acid anhydrides include phthalic anhydride,
Examples include tetra- or hexahydrophthalic anhydride, methylnadic anhydride, dodecylsuccinic anhydride, chlorendecic anhydride, adipic anhydride, maleic anhydride, pyromellitic anhydride, trimellitic anhydride, and the like. Preferably, these acid anhydrides are sufficiently purified and colorless to light-colored. As a curing accelerator, benzylmethylamine,
Pyridine, 2,4,6-tris(dimethylaminomethyl)phenol (DPM-30), K-603
(Tris 2-ethylhexoate salt of DMP-30),
Examples include triamylammonium phenolate, sodium hexanetriolate, 1,8-diazabicyclo(5,4,0)undensen-7, and the like. Further, the resin composition of the present invention includes a known diluent,
Fillers, extenders, dyes, plasticizers, etc. can be added depending on the purpose of use. The epoxy resin composition of the present invention provides a good cured product under commonly used curing conditions. That is, the curing temperature is usually 80 to 150°C for several minutes to several hours, but even if rapid curing is performed at 120 to 150°C, a sufficient coloring prevention effect is exhibited. [Example] Next, an example of the coloring prevention effect of a cured product using the epoxy resin composition of the present invention will be described. (Test method) 100g of methylhexahydrophthalic anhydride (or
90g), 1g (or 0.5g) of the curing accelerator, and 2g of the compound of the general formula () of the present invention, if necessary, heated to about 50°C and mixed to prepare a curing agent liquid, and add 100g of epoxy resin. to make a uniform resin liquid,
The mixture was poured into a mold that yields a cured product with a thickness of 4 mm, a width of 15 mm, and a length of 150 mm, and was heated at 130° C. for 30 minutes to cure. The cured product was then taken out from the mold and visually evaluated for coloring and transparency. In addition, the obtained cured product was left for 1000 hours at 100°C and then evaluated in the same way. For comparison, triphenyl phosphite and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-
Tests were also conducted with 10-oxide and without additives. (Evaluation method) ◎: Colorless and transparent ○: Transparent but slightly colored △: Transparent but slightly colored ×: Significantly colored The test results are shown in Table 1. That is, when the epoxy resin composition of the present invention is cured, the cured product is colorless and transparent, and its properties are not easily impaired even after long-term aging at high temperatures. 【table】

Claims (1)

[Claims] 1. An epoxy resin composition consisting essentially of (a) an epoxy resin, (b) an organic polybasic acid anhydride, and (c) a curing accelerator,
In the composition, the general formula () [In the formula, R ₁ and R ₂ each independently represent a halogen atom, an alkyl group, an aryl group, or an aralkyl group that may be optionally substituted with a halogen atom or an alkyl group, and x and y are 0 or 1 ~
3 is an integer, R ₃ is the residue of an organic compound having m hydroxyl groups, excluding the hydroxyl group,
And m represents an integer from 1 to 10. However, when m is 1, _R3 is a _C8 to _C20 alkyl group or an aryl group substituted at least at the 2-position with a tertiary alkyl group. ] An epoxy resin composition containing 0.1 to 20% by weight of an organic phosphorus compound represented by the formula above based on the total amount of components (a) to (c).