JPS5838719A - Thermosetting epoxy resin composition - Google Patents

Abstract

PURPOSE:The titled composition that is obtained by adding boron oxide to an epoxy resin as a curing agent, thus being suitably used as a heat-resistant insulation material, heat-resistant structure material or heat-resistant adhesive, because of its high heat resistance and hot-water resistance after curing. CONSTITUTION:2-300, preferably 100-200pts.wt. of boron oxide such as boron sesquioxide are added to 100pts.wt. of an epoxy resin such as a bisphenol A type to give the objective thermosetting epoxy resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to thermosetting epoxy resin compositions containing boron oxide as a curing agent.

Epoxy resins have ethylene oxide and hydroxyl functional groups, so they combine with curing agents such as amines, acid anhydrides, or boron trisulfide-amine complexes to improve adhesiveness, abrasion resistance, and chemical resistance. , a thermosetting resin material with excellent insulation properties and hardness. Therefore, epoxy resin compositions containing such curing agents have conventionally been used in a wide range of applications such as adhesives, electrical insulation materials, and civil engineering and construction materials.

However, these conventional thermosetting epoxy resin compositions do not have sufficient heat resistance after curing. In other words, the occurrence of thermal decomposition is observed at about 25,000 or more, and at about 500,000 or more
If it is stored in hot water at 0°C for a long time, it will not retain its shape and its hardness will become zero. Although the reason for this is not fully clear, it is probably because the chemical bond energy between the epoxy resin and the curing agent is low, and the composition decomposes at high temperatures or in hot water. Therefore, conventional epoxy resin compositions are used as heat-resistant insulating materials, heat-resistant structural materials, heat-resistant adhesives, etc. when used under high-temperature conditions, or when handling or using hot water in bathtubs, high-temperature submersible motors, etc. It is unsuitable as a material for cases.

The present inventors have conducted intensive research to eliminate the drawbacks of such conventional thermosetting epoxy resin compositions, and as a result, by adding boron oxide as a curing agent, which has completely different properties from conventional curing agents, A thermosetting epoxy resin composition and water scale with excellent heat resistance and hot water resistance were discovered, and the present invention was completed.

The boron oxide used in the present invention is diborotrioxide (B
One or a mixture of two or more of boron trioxide (B4O3), diboron trioxide (B4O3), and tetraboron pentoxide (B4O5) can be used, but boron trioxide is particularly preferred. Boric acid or metaboric acid can also be used as a curing agent, but is not preferred because its effects on heat resistance and hot water resistance are insufficient. The amount of boron oxide used is 2 to 30 parts per 100 parts (by weight, same below) of the epoxy resin.
0! , preferably 100 to 200 parts. If the amount used is less than 2 parts, sufficient heat resistance and hot water resistance cannot be achieved after curing, and curing takes a long time. Moreover, if more than 300 parts are used, the curing time becomes too short, which is not preferable for working, and the hot water resistance also deteriorates.

The epoxy resin used in the present invention is not particularly limited, but preferably, for example, bisphenol A is in a liquid or solid state at room temperature, but it may be in any state.

When the thermosetting epoxy resin composition of the present invention is solid at room temperature, it is prepared by heating the epoxy resin to about 75°C to make it fluid and then adding boron oxide. As the number of additives increases, the curing time becomes shorter, so the curing temperature in operation is limited. For example, when boron oxide is used in an amount of 50 to 200 parts per 100 parts of epoxy resin, the curing temperature should be 80°O or higher.

In addition, during the initial process of curing, boron oxide particles tend to aggregate, so when used for cast molding, for example, in order to obtain a uniformly cured product, it is necessary to stir thoroughly before use and then stir. However, it is preferable to proceed with curing to a certain degree of viscosity, then pour it out, and finally allow it to harden completely.

The thermosetting epoxy resin composition thus obtained is 250
It has a heat softening temperature of 0.00 or higher, and hardly loses its mechanical strength even if it is left in hot water or steam at 100 to 300 °C for 100 hours.

Next, the present suction will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is limited only to these Examples.
It's not something you can do.

Example 1 100 parts of liquid Epicoat 828 (manufactured by Mitsubishi Yuka) was used as an epoxy resin, heated to 4000 ℃, 100 parts of diboron trifluoride was added with stirring, and the mixture was gradually cured for 15 minutes (hereinafter referred to as (referred to as first curing), then casting,
It was cured at 60'O for 3 hours (hereinafter referred to as second curing), and finally at 200'O for 2 hours (hereinafter referred to as sixth curing) to complete curing.

The obtained cured material was tested for its primary properties by the following method.

(1) Thermogravimetric Analysis Three parts (mg) of the powdered test sample were measured in the air using a thermostat to measure the change in weight of the sample with respect to humidity. Note that the temperature increase rate was 10°0/min. Figure 1 shows the change in weight retention with respect to temperature.

(2) Using a thermal softening temperature thermomechanical analyzer (#@Shimadzu Corporation, model TMA (funded)), a measurement of 5 mm x 5 mm x was performed using the penetration method.
A 1 mm plate-shaped test piece was placed under a load of 9/am2 at 25 mm.
Measured by a heating rate of 10oO/min. The results obtained are shown in Table 1.

(3) Hot water test j Qmm x 2 parts mrn x 2mm (7) Plate-shaped (7) Test piece Totally left in 500'O steam for 100 hours, then taken out into the air and allowed to cool to room temperature.

The retention rate of the bending strength of this test piece was measured by the method of J.Eng. S-6911.

The results obtained are shown in Table 1.

Example 2 A thermosetting resin composition was obtained in the same manner as in Example 1, except that solid DIN439 (manufactured by Dow Chemical Co., USA) was used as the epoxy resin.

This composition was cured under the conditions shown in Table 1, and the resulting cured material was tested in the same manner as in Example 1. The results of the thermogravimetric analysis obtained are shown in FIG. 1, and the results of the thermal softening point and hot water test are shown in Table 1.

Examples 5 to 6 Type and usage amount of epoxy resin, type and usage amount of curing agent, and 1st & I! A cured material was obtained by carrying out the same operations as in Example 1, except that the conditions for curing and second curing were changed to those shown in Table 1.

The test results are shown in Table 1 and FIG.

Comparative Examples 1 to 5 The operations were carried out in the same manner as in Example 1, except that the type and amount of epoxy resin, the type and amount of curing agent, and the conditions for first curing and second curing were changed to those shown in Table 1. I obtained a cured material.

The test results are shown in Table 1 and FIG.

From FIG. 1, it can be seen that the composition of the present invention after curing has a lower weight loss rate at high temperatures of 600° a or higher than that of the conventional composition. Furthermore, from Table 1, the composition of the present invention after curing has a bending strength of 8 after being left in hot water at a high heat softening temperature of 250°a or more and 600°a for 100 hours.
It can be seen that it has a high retention rate of 0% or more.

As mentioned above, the thermosetting epoxy resin composition of the present invention can provide a cured product having higher heat resistance and UM hydrothermal properties than conventional ones, so it can be used as a heat-resistant insulating material,
゛It can be applied to heat-resistant structural materials, heat-resistant adhesives, etc.

[Brief explanation of drawings]

FIG. 1 is a graph showing the change in weight retention with respect to temperature of the epoxy resin composition after curing. (Main symbols in the drawings) (1&) to (2&): Characteristic lines (1b) to (21:+) showing the weight retention of the cured products obtained in Examples 1 and 2: Seen in Comparative Examples 1 and 2 Characteristic line showing the weight retention rate of the cured product. 'T+'j'l Agency 1<Palace'
-゛'1, =IIl'lυ) Display Patent application 1973
No. 6-137325 2, Name of the invention Thermosetting evo-cow arm composition 3-? +Ii+E person 5, symmetry of the amendment (1) Grasping of the “detailed description of the invention” in the specification (2) Drawing 6, content of the amendment (1) “And Figure 1” on page 7, line 3 of the specification Delete. (2) Drawing (Fig. 1) that has been revised from the drawing (Fig. 1)
Correct as shown below. 7. List of attached documents

Claims (1)

[Claims] (1) For 100 parts of epoxy resin, 2 parts of boron oxide
500 parts by weight of an epoxy resin composition as a curing agent.