JPH0725989A - Heat-hardening epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain a heat-hardening epoxy resin composition whose curing ability and storage stability are compatible with each other on practical level. CONSTITUTION:This heat-hardening epoxy resin is obtained by compounding the components (a), (b) and (c) shown below. (a) An epoxy resin having >=2 epoxy groups in a molecule. (b) A hardener. (c) A potential cure accelerator carrying a cure accelerator and a metallic ion among layers of an inorganic laminate compound having ion-exchanging function.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting epoxy resin composition which is excellent in curability and storage stability at room temperature. The composition of the present invention is a coating material, an adhesive, a laminated material (board), a molding material. Also, it can be used in various fields where epoxy resin has been conventionally used such as a sealing material.

[0002]

2. Description of the Related Art Generally, an epoxy resin composition comprises an epoxy resin which is a main material, a curing agent and a curing accelerator. The curing agent and the main agent are separately stored, and when they are used, they are mixed and used. There is a liquid type) and a type in which a curing agent and a main agent are already mixed (called a one-component type). In these types, the labor of weighing and blending is unnecessary when using,
A one-pack type epoxy resin composition is preferred because it has advantages such as no mixing error and less material loss. The one-pack type epoxy resin composition has a limitation in usable time because the curing reaction gradually progresses with the lapse of storage time, and various additives or storage methods are used to alleviate this limitation. Proposed. Increasing the storage stability in order to prolong the usable time of the epoxy resin composition generally leads to a decrease in the curability of the epoxy resin composition, so that a practical one-pack type epoxy resin composition is prepared. In order to develop, of the epoxy resin composition,
It is important to achieve both curability and storage stability. Currently, in order to achieve both curability and storage stability, a method of transporting a one-pack type epoxy resin composition at low temperature or storing at low temperature is adopted. Since the cost of storage greatly increases, it is strongly desired to enhance the storage stability at room temperature without impairing the curability of the epoxy resin composition. Conventionally, in order to achieve both curability and storage stability of the epoxy resin composition,
Research on latent curing accelerators has been extensively conducted, and as a result, many latent curing accelerators have been proposed, but each proposal satisfies practical requirements regarding curability and storage stability at room temperature. It wasn't something. In addition, many proposals have been made to impart latentity by using a microencapsulated curing accelerator, but at the time of premixing with a hot roll, the capsules are destroyed because high shear stress is applied to the capsules. There were drawbacks such as loss of sex.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermosetting epoxy resin composition which realizes both curability and storage stability, which were insufficient in the prior art, at a practical level. It is a thing.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors found that a curing accelerator and a metal ion supported between layers of an ion-exchangeable layered inorganic compound are latently cured. It is effective as an accelerator, and by incorporating this in an epoxy resin composition, new knowledge that the storage stability can be improved without impairing the curability of the epoxy resin is obtained, and the present invention is completed. Came to.
That is, the present invention is a thermosetting epoxy resin composition characterized by containing the following components (a), (b) and (c). (A) Epoxy resin having two or more epoxy groups in one molecule (b) Curing agent (c) Curing accelerator and latent curing accelerator having metal ions supported between layers of ion-exchangeable layered inorganic compound The present invention will be described in detail.

Epoxy Resin The epoxy resin in the present invention has two or more epoxy groups in one molecule and may be of any type as long as it can be cured. Preferable specific examples include phenol / novolak type epoxy resin, orthocresol / novolak type epoxy resin, bisphenol F type epoxy resin, alicyclic epoxy resin and the like, bromide of these resins and the like, and mixtures thereof and the like. is there.

Curing Agent The curing agent in the present invention is an epoxy resin curing agent, and any conventionally known curing agent can be used. For example, methyl butylene tetrahydrophthalic anhydride, methyl nadic acid, phthalic anhydride, mellitic acid anhydride, hettic acid anhydride, trimellitic acid anhydride, acid anhydrides such as tetracarboxylic acid pyromellitic dianhydride; aliphatic amines, Amine-based curing agents such as alicyclic amines, benzylmethylamine, diaminodiphenylmethane, and aromatic amines such as metaphenylenediamine. Mercaptan-based curing agents, dicyandiamide, and phenol-based curing agents such as phenol novolac resins and cresol novolac resins. . The preferable blending ratio of the curing agent is not particularly limited, but as is well known, it is desirable to prepare such that the epoxy groups of the epoxy resin and the active hydrogen of the curing agent are close to equivalent amounts.
For example, with respect to 100 parts by weight of a brominated bisphenol A type epoxy resin (hereinafter simply referred to as "part"), 10 to 70 parts of a phenol novolac resin may be blended.

Latent Curing Accelerator The latent curing accelerator in the present invention is one in which a curing accelerator for an epoxy resin and a metal ion are supported between layers of an ion-exchange layered inorganic compound. Ion-exchangeable layered inorganic compound An ion-exchanged layered inorganic compound has an ion-exchange function because the layer is not electrically neutral and therefore has oppositely charged ions between the layers. Is. Preferred ion-exchangeable layered inorganic compounds include, for example, silicates such as montmorillonite, vermiculite, beidellite, kaolinite, dikite, nacrite, halloysite, smectite, allophane, heractite, sepiolite, bentonite, pyrophyllite, muscovite, margarite. , Clay minerals such as antigorite, chrysotile, talc, phlogopite, xanthophyllite; hydrous sodium silicates such as kanemite, macatite, ilaite, magadiite, kenyaite; calcium silicates such as tobermorite; zirconium phosphate,
Phosphates of tetravalent metals such as titanium phosphate; other titanium such as potassium titanate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, cobalt titanate, nickel titanate, lead titanate and zinc titanate. Acid salt; other, uranate, vanadate,
There are niobates, tungstates, molybdates, hydrotalcite compounds, aluminates, basic copper acetate and the like. Preferred as the ion-exchangeable layered inorganic compound in the present invention are those in which the exchangeable ions between the layers are H type, and particularly preferred are tetravalent metal phosphates such as zirconium phosphate, titanium phosphate and tin phosphate. is there. Regarding the particle size of the latent curing accelerator, it is very important to maintain the dispersibility of the epoxy resin composition in a molten state, and the average particle size is preferably 5 μm or less, more preferably 1 μm or less. Is good.

Curing accelerator The curing accelerator is not reactive with the epoxy resin, but has a function of lowering the activation energy of the curing reaction, and is known as a curing accelerator for the epoxy resin in the present invention. Any of the above compounds can be used. Preferred specific examples include imidazoles, tertiary amines, and tertiary phosphines. Among these, imidazoles,
Tertiary amines are preferred. Specific compounds include imidazole, benzimidazole, 2-ethyl-4-methylimidazole, 2-methylimidazole, tridimethylaminophenol, tridimethylaminomethylphenol, triethanolamine, benzylmethylamine, hexamethylenetetramine, triethylenediamine, quinoline. , N-methylmorpholine, dimethylaniline, dimethylcyclohexylamine, 1,8-diazabicyclo (5,4,0) undecene-7 (DBU), 1,4-diaza-bicyclo (2,2,2) octane and triphenyl. There are phosphines.

Metal ion A metal ion promotes release of the curing accelerator from the ion-exchangeable layered inorganic compound, and any ion can be used as long as it can be supported between the layers of the ion-exchanged layered inorganic compound. . Specific examples of preferable metal ions include alkali metals such as sodium, lithium and potassium, and alkaline earth metals such as calcium and magnesium. The preferable amount of the metal ion depends on the kind of the metal ion, but the amount that gives the fastest release rate of the curing accelerator is preferable, based on the saturated ion exchange capacity of the metal ion of the ion-exchangeable layered inorganic compound. It is preferably about 5 to 60%. For example, the total ion exchange capacity is 6.7 m
In the case of sodium ions, zirconium phosphate having an eq / g of 0.3 to 4 meq / g is preferably loaded.

Supporting Method There is no particular limitation on the method of supporting the curing accelerator and the metal ion between the layers of the ion-exchangeable layered inorganic compound, and the curing accelerator and the metal ion can be ion-exchanged in an environment capable of ion exchange. When contacted with the exchangeable layered inorganic compound, the curing accelerator and the metal ion can be easily supported between the layers of the ion exchangeable layered inorganic compound due to the ion exchange ability of the ion exchangeable layered inorganic compound. Specific methods include, for example, the following methods. That is, a predetermined amount of a compound having a curing accelerator and metal ions to be supported between layers is weighed,
If it is water-soluble, it is added to water or warm water, and if it is water-insoluble or sparingly water-soluble, the curing accelerator is added by adding it to an organic solvent capable of dissolving the compound having a metal ion. And a solution containing metal ions are prepared. Next, an ion-exchangeable layered inorganic compound is added to this solution and stirred for several hours to obtain a curing accelerator and a latent curing accelerator having metal ions supported between the layers. Further, as the order of carrying the curing accelerator and the metal ion, first, a method of carrying a predetermined amount of the metal ion and then carrying the predetermined amount of the curing accelerator, a method of simultaneously carrying the curing accelerator and the predetermined amount of the metal ion, and hardening promotion There is a method of supporting a predetermined amount of the metal ion after supporting the predetermined amount of the agent. The amount of the curing accelerator and the metal ion supported can be freely controlled by changing the solution concentration of the curing accelerator and the metal ion, and the amount of the ion-exchangeable layered inorganic compound added to the solution of the curing accelerator and the metal ion. Can be done.

Blending of latent curing accelerator into epoxy resin composition The preferable blending amount of latent curing accelerator into the epoxy resin composition is the type and amount of epoxy resin, and the type and amount of curing agent. The amount of the curing accelerator supported between the layers of the ion-exchangeable layered anonymous compound may be the same as the amount of the curing accelerator directly added to the epoxy resin composition. For example, bisphenol A type epoxy resin 10
When a curing accelerator is directly added to a composition consisting of 0 part and 60 parts of a phenol novolac resin, the amount of the curing accelerator added is conventionally in the range of 0.1 to 1.0 part. A latent curing accelerator having the same amount of curing accelerator as the above can be blended.

Other components In the epoxy resin composition of the present invention, if necessary, an inorganic filler, a halogenated epoxy resin, a flame retardant such as antimony trioxide, a coloring agent such as carbon black, a silane coupling agent, etc. Surface treating agents, carnauba wax, montan wax, releasing agents such as stearic acid, thickeners, antioxidants and other additives.

The composition of the present invention may be prepared by blending the above-mentioned various components in a predetermined composition ratio and mixing them with a mixer or the like. When the composition is solid at room temperature, it is further melt-mixed with a hot roll or a kneader. Or by mixing an organic solvent capable of dissolving the epoxy resin and the curing agent and uniformly mixing them. Specific examples of the organic solvent include acetone, methyl ethyl ketone, dimethylformamide, and the like, and the blending amount of these may be in accordance with a conventionally used conventional method. When the curing accelerator is wrapped with microcapsules, high shear stress is applied during mixing with a heat roll or the like, and microcapsules that are low-strength composites are destroyed, resulting in impaired latent curability. Although there was a problem, the composition of the present invention itself contains a latent curing accelerator in which a curing accelerator is supported between layers of a compound having sufficiently high strength, so that it is mixed by a heat roll or the like. Occasionally, the latent curing accelerator is physically destroyed and the latent curability is not deteriorated.

Uses The composition of the present invention is useful in various fields in which an epoxy resin has been conventionally used such as a coating material, an adhesive, a cast product, a laminated material such as a laminated board, and a molding material.

The composition of the present invention has substantially no curability at room temperature and is extremely excellent in storage stability, and the curing is performed by heating. The heating conditions such as the heating temperature, the heating time, and the heating device are not particularly limited, and the usual method may be used according to various applications.

○ Action The reason why the composition of the present invention exhibits so-called latent curing reaction is not clear in detail, but the present inventors consider as follows. That is, since the curing accelerator is supported between the layers of the ion-exchangeable layered inorganic compound, at a melting temperature or lower that is usually adopted for preparing a thermosetting epoxy resin composition, the curing accelerator is removed from the layers. Not released, the contact between the curing accelerator and the curing agent is limited only to the layer end surface of the layered inorganic compound, the curing reaction is substantially stopped, while heating the epoxy resin composition to the curing temperature,
It is presumed that the curing reaction is promoted because the curing accelerator supported between the layers of the layered inorganic compound is released from the layers to allow contact with the curing agent. When a curing accelerator and a metal ion are allowed to coexist between the layers of the ion-exchangeable layered inorganic compound, the coexistence of the metal ion changes the charge in the layer of the ion-exchangeable layered inorganic compound and carries the curing accelerator. It is presumed that the curability is improved because the force is reduced and the supported curing accelerator is easily released into the epoxy resin composition.

[0017]

【Example】

Reference Examples 1 to 4 (Preparation of latent curing accelerator) 1.0 g or 3.0 g of sodium hydroxide was dissolved in 500 ml of pure water to prepare two kinds of aqueous solutions having different sodium ion concentrations. In these aqueous solutions, zirconium phosphate [Zr (HPO ₄ ) ₂ · H
₂ O] 25.0 g was added, and the mixture was shaken and agitated at 40 ° C. for 15 hours, suction filtered, and the residue was dried at 90 ° C. for 24 hours to give two kinds of ions having sodium ions supported between layers. An exchangeable layered inorganic compound was obtained. Using the curing accelerator imidazole or 2-methylimidazole, the former 3.4 g or the latter 4.1 g was dissolved in 300 ml of pure water to prepare two kinds of aqueous solutions. To each of these solutions, 5.0 g of each of the two types of ion-exchangeable layered inorganic compounds supporting sodium ions as described above was added, and the mixture was shaken and stirred at 40 ° C. for 15 hours, and then suction-filtered. Was carried out and the residue was dried at 90 ° C. for 24 hours to obtain four latent curing accelerators. The conditions for preparing the latent curing accelerator thus obtained are shown in Table 1 below. In addition, the latent curing accelerator No. No. of the reference example which prepared each.
Is the same as.

[0018]

[Table 1] Note) Unit of supported amount: meq / g (The number in parentheses indicates the weight percentage with respect to the latent curing accelerator.)

Comparative Reference Examples 1 and 2 3.4 g of imidazole and 4.1 g of 2-methylimidazole were separately dissolved in 300 ml of pure water,
Two aqueous solutions were prepared. 5.0 g of zirconium phosphate [Zr (HPO ₄ ) ₂ · H ₂ O] was added to these aqueous solutions.
After adding and shaking and stirring at 40 ° C for 15 hours, suction filtration is performed, and the residue is dried at 90 ° C for 24 hours to promote latent curing promotion by supporting only a curing accelerator without supporting metal ions. I got an agent. The preparation conditions of the latent curing accelerator thus obtained are shown in Table 2 below.

[0020]

[Table 2] Note) Unit of supported amount: meq / g (The number in parentheses indicates the weight percentage with respect to the latent curing accelerator.)

The latent curing accelerator thus obtained is referred to as No. Is the N of the comparative reference example as follows.
o. It corresponds to.

Examples 1 to 4 No. For each of 1 to 4 latent curing accelerators,
3.3 parts of this was added to the composition shown in Table 3 below, and these were uniformly mixed using a mixer and then desolvated with an evaporator at 30 ° C. for 2 hours to obtain 4 kinds of thermosetting epoxy resin compositions. I got a thing. No. A thermosetting epoxy resin composition containing the latent curing accelerator of Example 1 was used in Example 1, No. The thermosetting epoxy resin composition containing the latent curing accelerator of No. 2 was designated as Example 2, and thereafter, in the same manner as above, No. A thermosetting epoxy resin composition containing the latent curing accelerator of No. 4 is set as Example 4.

[0023]

[Table 3] * 1: Yuka Shell Co., Ltd. product name 828 * 2: Nippon Kayaku Co., Ltd. product name PN-100

Comparative Example 1 In Example 1, 3.3 parts of latent curing accelerator No.
0.46 parts (latent curing accelerator N instead of 1)
o. The same amount of imidazole as the curing accelerator supported on 1) was added to the compositions in Table 3 above, and a high-viscosity liquid thermosetting epoxy resin composition was obtained by the same method.

COMPARATIVE EXAMPLE 2 In Example 1, the latent curing accelerator No. 3 carrying a metal ion and a curing accelerator was carried out. Instead of blending 1, the latent curing accelerator No. 1 supporting only the curing accelerator. 5
A thermosetting epoxy resin composition in the form of a highly viscous liquid was obtained by adding it to the composition shown in Table 3 and following the same procedure.

Comparative Example 3 In Example 3, 3.3 parts of latent curing accelerator No.
0.66 parts (latent curing accelerator N instead of 3)
o. 2-methylimidazole (the same amount as the curing accelerator supported on 3) was added to the composition in Table 3 above, and a high-viscosity liquid thermosetting epoxy resin composition was obtained by the same method.

COMPARATIVE EXAMPLE 4 In Example 3, the latent curing accelerator No. 3 carrying a metal ion and a curing accelerator was used. Instead of blending 3, the latent curing accelerator No. 3 supporting only the curing accelerator was used. 6
A thermosetting epoxy resin composition in the form of a highly viscous liquid was obtained by adding it to the composition shown in Table 3 and following the same procedure.

Evaluation Method of Curability and Storage Stability of Epoxy Resin Composition-Evaluation of Curability About thermosetting epoxy resin compositions in high viscosity liquid state prepared in Examples 1 to 4 and Comparative Examples 1 to 4 The curability was evaluated using a gelation tester. The evaluation conditions are as follows. Temperature: 170 ° C Gel time: Time from the start of heating to gelation (unit: minutes)

Evaluation of Storage Stability The thermosetting epoxy resin compositions in the form of high viscosity liquid prepared in Examples 1 to 4 and Comparative Examples 1 to 4 had a gel time of 50% when stored at 40 ° C. It was evaluated by the number of days until.

The evaluation results of curability and storage stability are shown in Table 4 below. The storage stability shown in Table 4 below and
The evaluation criteria are shown below. (Display of storage stability) A: 10 days or more B: 4 days or less (Display of comprehensive evaluation) ◎: Particularly excellent as overall evaluation ○: Excellent as overall evaluation ×: Poor storage stability or curability

[0031]

[Table 4]

As can be seen by comparing the results of Examples 1 and 2 in Table 4 and Comparative Example 1 and Examples 3 and 4 and Comparative Example 3, when the curing accelerator is contained in the epoxy resin composition, curing acceleration is promoted. Compared with the case where the curing agent is directly compounded, when the latent curing accelerator in which the curing accelerator is supported on the ion-exchangeable layered inorganic compound is compounded, the epoxy resin composition has practical curability and at the same time storage stability. The character is remarkably excellent. Further, as can be seen by comparing the results of Examples 1 and 2 in Table 4 with Comparative Example 2 and Examples 3 and 4, and Comparative Example 4,
Compared with the case where only the latent curing accelerator is loaded with the curing accelerator, when the metal ion is further loaded, the epoxy resin composition has excellent storage stability, and at the same time,
The curability is further enhanced.

[0033]

INDUSTRIAL APPLICABILITY The composition of the present invention is an excellent thermosetting epoxy resin composition capable of sufficiently satisfying the requirements of a practical level in terms of both storage stability and curability at room temperature. It is useful in various fields where epoxy resins have been conventionally used such as laminated materials such as plates, molding materials and sealing materials.

Continued Front Page (72) Inventor Tomohisa Iinuma 1-1 Funami-cho, Minato-ku, Nagoya, Aichi Prefecture Toagosei Chemical Industry Co., Ltd. Nagoya Research Institute

Claims (1)

[Claims] 1. A thermosetting epoxy resin composition comprising the following components (a), (b) and (c). (A) Epoxy resin having two or more epoxy groups in one molecule (b) Curing agent (c) Curing accelerator and latent curing accelerator having metal ions supported between layers of ion-exchangeable layered inorganic compound