JPH06198644A - Molding method for epoxy resin tablet - Google Patents

Abstract

PURPOSE:To form epoxy resin into tablet by polymer processing without necessitating heating, crushing, and compressing processes at ordinary temperature and pressure, which has excellent preservation stability at room temperature and manifests excellent fluidity and clearance filling property by being heated so as to be solidified with reaction. CONSTITUTION:Crystal nucleus is added to a liquid epoxy resin, which is in an excessively cooled state at room temperature, so as to generate crystallization phenomenon in the resin. The resin is crystallized and solidified, and molded into tablet at ordinary temperature and pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding an epoxy resin tablet, which is capable of molding an epoxy resin into a tablet at room temperature and atmospheric pressure, and in particular, the obtained solid epoxy resin tablet is stored at room temperature. The present invention relates to a molding method of an epoxy resin tablet which is excellent in stability and exhibits excellent fluidity and gap filling property by heating and can be solidified by reaction.

[0002]

2. Description of the Related Art As a method for molding an epoxy resin tablet, there has been known a method in which a thermosetting epoxy resin is melted by heating, extruded, cut into a tablet size, and rapidly cooled to obtain a tablet. There is.

Further, there is also adopted a method in which an epoxy resin is partially reacted with a curing agent to be cooled and solidified in a B stage state, that is, a semi-cured state, crushed while suppressing the subsequent reaction, and a tablet is obtained by tableting. Has been done.

[0004]

However, the former method requires heating, cooling, and swarf steps, and thus requires these facilities.

In the latter method, since the crushed resin is tableted by tableting, voids are unavoidably generated in the tablet, and it is difficult to mold a high-density tablet. Molding under high pressure was necessary, or vacuum molding in the tableting mold was necessary. In addition, this method requires heating, cooling, and pulverization steps, so these facilities are required. In addition, in this method, since the reaction is partially cooled and pulverized by cooling, there is a problem in storage stability, and careful storage is required.

In order to solve the above-mentioned drawbacks of the known art,
A method of making tablets using the crystallinity of an epoxy resin is proposed in, for example, Japanese Patent Laid-Open No. 30025/1993. However, since this method heats and melts a crystalline epoxy resin which is solid at room temperature and contains a latent curing agent and the like, there is a problem in its stability.

Therefore, an object of the present invention is to mold an epoxy resin into a tablet at room temperature and atmospheric pressure, and the tablet obtained has excellent storage stability at room temperature and excellent fluidity and gap filling by heating. It is an object of the present invention to provide a method for molding an epoxy resin tablet which exhibits the properties and can be solidified by reaction and which has improved the above-mentioned drawbacks of the known art.

[0008]

In order to achieve the above-mentioned object, according to the present invention, crystal nuclei are added to a liquid epoxy resin which is supercooled at room temperature to cause the resin to undergo a crystallization phenomenon. It is characterized in that it is crystallized and solidified, and thereby it is formed into a tablet at room temperature and normal pressure.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention is described in detail below. The liquid epoxy resin in the supercooled state at room temperature used in the present invention contains at least two compounds in total of 80% by weight or more among the following compounds A to C, and the total amount of the compound A and / or the compound B. Contains 50% by weight or more of all compounds. Compound A:

[Chemical 4] Compound B:

[Chemical 5] R = H, or CH ₃ compound C:

[Chemical 6] R = H or CH ₃ , n = 0.1 or less

The compound A is a polyhydric phenol glycidyl ether, and in the present invention, a compound having a purity of 95% or more is preferable. If it is less than this range, crystallization does not occur or the crystallization speed becomes extremely slow, which is not practical. Specific examples of this compound include R manufactured by Nippon Kayaku Co., Ltd.
E701 is mentioned. This compound A has excellent crystallinity in the presence of crystal nuclei and retains the shape after crystal solidification.

The compound B is an epoxy resin which is crystalline at room temperature, and as the commercially available one, YX-4000 manufactured by Yuka Shell Epoxy Co., Ltd. may be mentioned. By adding compound A and / or compound C to this and heating and melting, it becomes a liquid in a supercooled state at room temperature, and the liquid state is maintained for a relatively long time. Further, when the crystal nuclei are present, the crystals solidify rapidly.

Compound C is a bisphenol type epoxy resin. It is known that commercially available bisphenol type epoxy resins, for example, Epicoat 828, 807 (n = 0.11 to 0.14) also crystallize at room temperature, but in the present invention, such a resin is added when crystal nuclei are added. Is not suitable because the rate of crystal formation is slow. In the present invention, n ≦ 0.1 is used, and more preferably n ≦ 0.05.

The liquid epoxy resin which is supercooled at room temperature according to the present invention precipitates and solidifies crystals in a short time of several tens of minutes to several hours in the presence of a substance serving as a crystal nucleus,
Further, when there is no substance that becomes crystal nuclei, the supercooled state is maintained for a relatively long period of time.

As the above-mentioned crystal nuclei, powders such as latent hardeners and fillers are used. As the latent curing agent, a generally used latent curing agent can be used as long as it is in a powder state at room temperature. Examples thereof include dicyandiamide, dibasic hydrazides, imidazoles, imidazole epoxy adducts, boron trifluoride amine complex, and the like. As the filler, if it is also in a powder state at room temperature, commonly used fillers such as silica and titanium oxide, and fine powder rubber or elastomer can be used. The amount of these crystal nuclei added is preferably 20 to 400% by weight relative to the liquid epoxy resin in a supercooled state.

In the present invention, in addition to the above-mentioned crystal nuclei, generally used plasticizers and additives may be used as long as they do not hinder crystallization.
It is also possible to use a powdery elastomer or rubber as crystal nuclei, and it is also possible to use a dispersed elastomer-containing epoxy resin obtained by vulcanizing the elastomer in a liquid epoxy resin while stirring.

Further, in the molding of the present invention, powders of these latent curing agents, fillers and the like are added as crystal nuclei to the liquid epoxy resin in a supercooled state at room temperature, and the liquid epoxy resin is preliminarily added in this state. By pouring into a prepared mold having a desired shape, a high density epoxy resin tablet is obtained at room temperature and normal pressure.

The shape of the molding die may be a fairly small shape or a complicated shape as long as the resin liquid spreads. The tablet mentioned here does not necessarily mean only a columnar one, but also includes a shape that can fill the volume of the component to be sealed as it is. It also includes things such as precoating.

The tablet formed by the present invention is further melted by permeating into the details of the component by heating in a state adapted to the component, and then reactively cured. By this method, an epoxy resin tablet suitable for potting sealing and adhesion is obtained.

[0019]

The present invention described above is one in which crystal nuclei are simply added to a liquid epoxy resin that is supercooled at room temperature, and this is poured into a desired molding die to cause the resin to crystallize and solidify. Since it does not require heating, pressurization, crushing, compression, etc., these facilities are not required, and at room temperature,
It can be molded into tablets under normal pressure. Furthermore, the obtained solid epoxy resin tablet has few voids, is strong and does not chip, and is excellent in storage stability at room temperature and is also excellent in fluidity by heating. Further, the shape at the time of molding can be easily changed as necessary.

[0020]

EXAMPLE The formulations shown in Examples 1 to 7 and Comparative Examples 1 to 4 in Table 1 were mixed and stirred, and immediately after the mixture was in a liquid state, a radius of 3 cm,
It is poured into a cylindrical mold having a height of 1 cm and the time until solidification is measured, and the results are shown in Table 1.

[0021]

[Table 1]

In Table 1, No .: Compound A (RE-701 manufactured by Nippon Kayaku Co., Ltd.) 〃: Compound B (however, R = CH ₃ ) 〃: Compound C (however, R = CH ₃ , n = 0.01) ) 〃: Compound C (however, R = H, n = 0.03) 〃: Compound C (however, R = CH ₃ , n = 0.14) 〃: Compound C (however, R = H, n = 0.11) 〃: Latent Hardening agent (manufactured by Ajinomoto Co.) 〃: Silica-based filler (manufactured by Tatsumori Co., Ltd.) However, the numbers and are compound C outside the range of compound C of the present invention.

Further, in Table 1, the storage stability of the resin is such that crystals are precipitated when the resin is (melted) mixed and returned to room temperature (25 ° C.) and then stored as it is without adding a substance as a core. Is the number of days until the crystals solidify, and the crystallization time is the time until the crystals precipitate and solidify at 25 ° C. after the crystal nuclei are charged. In Comparative Example 4, crystallization started as soon as the curing agent and the filler (crystal nuclei) were added, and the crystals were completely solidified in 5 minutes without being sufficiently mixed.

Further, as is clear from Table 1, in Examples 1 to 7 of the present invention, the total of at least two compounds among compounds A to C is 80% by weight or more, and all are Crystallization time is short. On the other hand, in Comparative Examples 1 to 4, none of the compounds A to C was used (Comparative Examples 1 and 2), or the sum of the two compounds was 80% by weight or less (Comparative Example 3), Furthermore, only one compound was used (Comparative Example 4), and therefore the crystallization time was either long or too short.

Reaction Curability Test When the solid tablets obtained in Examples 1 to 7 in Table 1 were heated in a hot air dryer at 100 ° C., they were melted and cured, and after 1 hour, completely reacted epoxy cured products were obtained. .

Stability of Tablets The solid tablets obtained in Examples 1 to 7 in Table 1 were stored at room temperature for 6 months and then heated in a hot air dryer at 100 ° C. to react and cure, and after 1 hour, completely reacted epoxy. A cured product was obtained. The epoxy resin thus obtained did not differ in performance from that obtained by reacting immediately after production.

Molding of tablets of complicated shape The liquid epoxy resins of Examples 1 to 7 in Table 1 are poured into a mold as shown in FIG. 1 and left at 25 ° C. for 3 to 6 hours to obtain the mixture shown in FIG.
It was possible to obtain an unreacted solid resin (epoxy resin tablet) 2 having such a shape. The tablet resin obtained by this method is effective for sealing relays and the like.

[0028]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the epoxy resin can be molded into a tablet shape at normal temperature and normal pressure without requiring steps such as heating, crushing and compression, and the obtained tablet is at normal temperature. It has excellent storage stability at room temperature, and it can be solidified by heating by exhibiting excellent fluidity and gap filling properties.
This is a practically useful method.

[Brief description of drawings]

FIG. 1 is an example of a molding die used in the present invention.

2 is an epoxy resin tablet according to the present invention molded by using the mold of FIG.

[Explanation of symbols]

 1 Mold 2 Unreacted solid resin (epoxy resin tablet)

Claims (4)

[Claims] 1. A crystal epoxy is added to a liquid epoxy resin in a supercooled state at room temperature to cause the resin to crystallize and solidify, thereby forming a tablet at room temperature and atmospheric pressure. A method for molding an epoxy resin tablet, which is characterized by: 2. The molding method according to claim 1, wherein the crystal nucleus is a latent hardener or a filler. 3. The molding method according to claim 1, wherein the liquid epoxy resin in a supercooled state at room temperature contains at least two compounds of the following compounds A, B and C in a total amount of 80% by weight or more. Compound A: Compound B: R = H, or CH ₃ compound C: R = H or CH ₃ , n = 0.1 or less 4. The molding method according to claim 3, wherein the total amount of the compound A and / or the compound B is 50% by weight or more of the total amount of the compounds.