JPH06116359A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition, comprising an epoxy resin, a tetrafunctional epoxy resin and a curing agent and excellent in heat-resistant adhesion, impregnating properties and operating efficiency. CONSTITUTION:This resin composition is obtained by blending (A) an epoxy resin expressed by formula I (R is H or lower alkyl) (preferably having 100-110 deg.C glass transition temperature and 180-200 epoxy equiv.) with (B) a tetrafunctional epoxy resin expressed by formula II (G is formula III) (preferably having 80-100 deg.C glass transition temperature and 180-220 epoxy equiv.), (C) a curing agent {preferably a novolak type phenolic resin, expressed by formula IV [(n':n'') is (2:1)]} and having 90-110 deg.C softening point and 140-160 phenolic equiv.] and (D) a curing accelerator (preferably an imidazole resin expressed by formula V).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition having excellent heat resistance and impregnation property.

[0002]

2. Description of the Related Art In recent years, powder compositions, such as powder coatings, have been
It is widely used as a pollution-free, resource-saving and energy-saving paint, and is replacing the solvent-based paint that has been used conventionally.

However, since a general powder coating material has a high viscosity at the time of melting, it has an advantage that a thick film can be finished by one coating operation, but on the other hand, wettability with an object to be coated,
It has the drawback of poor penetration into details, that is, gap filling and thin film coating.

Further, with the recent expansion of applications, there has been a demand for improvement of the above-mentioned drawbacks as well as improvement of heat resistance and adhesiveness. In order to meet these demands, it is necessary to develop a coating material as a new material. Has become. Epoxy resin compositions are commonly used as the paints often used. Examples of the epoxy resin composition include bisphenol A type epoxy resin, novolac type epoxy resin,
An epoxy resin such as an alicyclic epoxy resin as a main component, which is mixed with a curing agent such as acid anhydride or polyamine, a curing accelerator such as a tertiary amine or imidazole, a filler, and other additives. Are known.

[0005]

However, the above epoxy resin composition is not yet satisfactory in terms of heat resistance. Considering the above heat resistance, a maleimide resin composition containing a maleimide resin as a main component is mentioned as being superior to the epoxy resin composition. However, when the above maleimide resin composition is used, the heat resistance is improved, but on the other hand, the coating film formed is fragile, resulting in a problem that the adhesive strength is significantly reduced.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an epoxy resin composition which is excellent in heat-resistant adhesiveness and impregnation property and is also excellent in workability.

[0007]

In order to achieve the above object, the present invention has as its first gist an epoxy resin composition containing the following components (A) to (C):

(A) An epoxy resin represented by the following general formula (1).

[Chemical 3] [In the above formula (1), R is H or a lower alkyl group. ] (B) A tetrafunctional epoxy resin represented by the following general formula (2).

[Chemical 4] (C) Hardener. A second gist is an epoxy resin composition containing a curing accelerator in addition to the components (A) to (C).

[0009]

That is, the present inventors have conducted a series of studies in order to obtain an epoxy resin composition having excellent fluidity and heat-resistant adhesiveness, and also excellent workability. As a result, when the specific epoxy resins (A component and B component) represented by the above general formulas (1) and (2) are used together as the main component, they have excellent impregnability (A component). The heat resistance (component B) is fully utilized, and the respective drawbacks [decrease in heat resistance (component A) and impregnation (component B)] are compensated for, and the fluidity is excellent, and in a high temperature atmosphere. The inventors have found that it is possible to suppress a decrease in adhesive force caused by heat history due to continuous use of the above, and have reached the present invention. Further, the above specific epoxy resin (A component and B
It has been found that the use of a curing accelerator in addition to the (component) is more effective.

Next, the present invention will be described in detail.

The epoxy resin composition of the present invention is obtained by using a specific epoxy resin (component A), a special epoxy resin (component B), and a curing agent (component C). Further, it is more effective to use a curing accelerator in the above components A to C.

The above-mentioned specific epoxy resin (component A) is represented by the following general formula (1), and is a crystalline epoxy resin which has been widely used conventionally. This particular epoxy resin (component A) has a very low viscosity in a high temperature atmosphere, and therefore has a characteristic of being excellent in impregnation property. This crystalline epoxy resin has a glass transition temperature of 100 to 1
Those having 10 ° C. and an epoxy equivalent of 180 to 200 are preferably used.

[0013]

[Chemical 5] [In the above formula (1), R is H or a lower alkyl group. ]

However, the above specific epoxy resin (component A) has an excellent impregnation property, but on the other hand, it has the drawback of being inferior in heat resistance.

The special epoxy resin (component B) is a tetrafunctional epoxy resin represented by the following general formula (2). Particularly, it is preferable to use one having a glass transition temperature of 80 to 100 ° C. and an epoxy equivalent of 180 to 220.

[0016]

[Chemical 6]

The tetrafunctional epoxy resin (component B) has a characteristic of being excellent in heat resistance in a high temperature atmosphere, contrary to the above crystalline epoxy resin (component A). On the other hand, the above-mentioned tetrafunctional epoxy resin (component B) is more reactive than other epoxy resins, and has the drawbacks of shortening gel time and impregnating property. As described above, by using the crystalline epoxy resin (component A) and the tetrafunctional epoxy resin (component B) together, the excellent properties of the impregnability of the component A and the heat resistance of the component B, which are advantages of each other, are utilized. However, it becomes possible to obtain an epoxy resin composition which is excellent in both impregnating property and heat resistant adhesiveness by compensating for the defects of both.

Further, in addition to the crystalline epoxy resin (component A) and the tetrafunctional epoxy resin (component B), other epoxy resins may be used. For example, a novolac epoxy resin represented by the following general formula (3) can be given. As the epoxy resin, one having a glass transition temperature of 80 to 90 ° C. and an epoxy equivalent of 210 to 230 is usually used.

[0019]

[Chemical 7]

The epoxy resin represented by the above general formula (3) is a widely used novolac epoxy resin, and is characterized by excellent heat resistance in a high temperature atmosphere like the tetrafunctional epoxy resin (component B). On the other hand, it has the drawback of high rigidity and poor mechanical strength. Also,
Since the melting point is also lower than that of the above-mentioned components A and B, it has the drawback of being poor in blocking resistance in a high temperature atmosphere. However, by using this novolac epoxy resin, it is possible to improve the decrease in impregnating property due to the blending of the tetrafunctional epoxy resin (component B).

In the above epoxy resin component,
When the crystalline epoxy resin (component A), the tetrafunctional epoxy resin (component B) and the novolac epoxy resin are used, the respective compounding ratios are such that the total epoxy resin component is 10
In 0 parts by weight (hereinafter abbreviated as "part"), the amount of the component A is 50 to 70.
It is preferable that the parts and the B components are set to 15 to 30 parts and the novolac epoxy resin is set to 15 to 35 parts. That is, when the component A is less than 50 parts in 100 parts of the epoxy resin component, the impregnating property of the obtained epoxy resin composition is remarkably lowered, and conversely, when it is more than 70 parts, the heat resistance tends to be lowered. Also, the epoxy resin component 100
This is because when the component B is less than 15 parts, the heat resistance of the obtained epoxy resin composition is remarkably reduced, and when it exceeds 30 parts, the impregnation property tends to be reduced. further,
This is because when the novolac epoxy resin is less than 15 parts in 100 parts of the epoxy resin component, the heat resistance of the obtained epoxy resin composition is remarkably reduced, and when it exceeds 35 parts, the blocking resistance tends to be lowered.

In addition to the above epoxy resin components, a commonly used epoxy resin is 20% by weight based on the total weight of the epoxy resin.
It is also possible to mix within the range. However, when the above-mentioned normally used epoxy resin is used, it may be difficult to prepare a powder coating, and in such a case, it is used as a solvent type coating.

The hardener (C component) used together with the epoxy resin component is not particularly limited and conventionally known ones can be used. In particular, the novolak type represented by the following general formula (4) is used. Preference is given to using phenolic resins. This novolac type phenol resin is a condensate of tertiary butyl novolac phenol resin and orthocresol novolac phenol. This novolac type phenol resin has a softening point of 90-
It is preferable to use one having a phenol equivalent of 140 to 160 at 110 ° C.

[0024]

[Chemical 8]

When the above novolac type phenol resin is used as the curing agent, the compounding amount thereof is preferably set to 40 to 70 parts with respect to 100 parts of the epoxy resin component. That is, when the compounding amount of the novolac type phenol resin is less than 40 parts, the reactivity (workability) of the obtained epoxy resin composition is remarkably lowered, and conversely, when it exceeds 70 parts, the heat resistance tends to be lowered. is there.

Further, it is preferable to add a curing accelerator in addition to the epoxy resin component and the curing agent (C component), and the curing accelerator is particularly represented by the following general formula (5). It is preferable to use an imidazole resin.

[0027]

[Chemical 9]

When an imidazole resin is used as the above curing accelerator, the compounding amount thereof is the epoxy resin component 10 mentioned above.
It is preferably set to 0.5 to 3.0 parts with respect to 0 parts. That is, if the blending amount of the imidazole resin is less than 0.5 part, the curing time may be long and the workability may be deteriorated.
On the contrary, if it exceeds 3.0 parts, the melting time tends to be shortened and the fluidity tends to be lowered.

In the epoxy resin composition of the present invention, in addition to the epoxy resin component, the curing agent and the curing accelerator, various conventionally used additives can be appropriately blended.

As the above-mentioned various additives, there are used fillers such as talc, silica sand, silica, calcium carbonate and barium sulfate, pigments such as carbon black, red iron oxide, titanium oxide, chromium oxide, cyanine blue and cyanine green, and other streams. Examples include regulators.

The amount of such additives to be added is usually preferably 0.5 to 200% by weight (hereinafter abbreviated as "%") of the entire epoxy resin composition, and particularly preferably 0. 5 to 50%.

The epoxy resin composition of the present invention is prepared by mixing the above-mentioned epoxy resin component, curing agent, curing accelerator, and various additives by a conventionally known means such as a melt mixing method. It can be manufactured by crushing and classifying.

The particle size in the classification is preferably set so as to pass through 30 mesh.

The epoxy resin composition thus obtained has a low viscosity when melted and an excellent gap filling property due to the action of the crystalline epoxy resin (component A) and tetrafunctional epoxy resin (component B). It has good wettability with respect to an object to be coated and coatability with a coating film, and has excellent heat resistance after curing.

[0035]

As described above, the epoxy resin composition of the present invention contains the crystalline epoxy resin represented by the general formula (1) and the tetrafunctional epoxy resin represented by the general formula (2). Therefore, by taking advantage of each of them, and by compensating each other's drawbacks, it is excellent in both adhesive strength in a high temperature atmosphere and shear adhesive strength after being left in a high temperature atmosphere, and also has good fluidity and excellent impregnation property. .

Next, examples will be described together with comparative examples.

First, prior to the examples, the following epoxy resins a to f, phenol resin g, maleimide resin h, diamine resin i and imidazole resin j were prepared.

[Epoxy resin a]

[Chemical 10] Glass transition temperature 100-110 ° C, epoxy equivalent 180
~ 200

[Epoxy resin b]

[Chemical 11] Glass transition temperature 80 to 90 ° C, epoxy equivalent 210 to 2
Thirty

[Epoxy resin c]

[Chemical 12] Glass transition temperature 80 to 100 ° C, epoxy equivalent 180 to
220

[Epoxy resins d to f]

[Chemical 13] (In the above structural formula, the epoxy resin d is α = 0 to 1,
Epoxy resin e is α = 2 to 3, and epoxy resin f is α = 4.
~ 5. )

[Phenolic resin g]

[Chemical 14] Softening point 90-110 ° C, phenol equivalent 140-160

[Maleimide resin h]

[Chemical 15]

[Diamine resin i]

[Chemical 16]

[Imidazole resin j]

[Chemical 17]

[0046]

Examples 1 to 8 and Comparative Examples 1 to 7 Epoxy resin compositions of interest by blending the components shown in Tables 1 to 3 below in the proportions shown in the table, melt-kneading and pulverizing Alternatively, a maleimide resin composition was obtained.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

With respect to the epoxy resin composition and maleimide resin composition of the example product and the comparative example product thus obtained, the shear adhesive strength at 200 ° C., the heat resistance rate, the gap filling rate, and the crack generation rate were measured by the following methods. It was measured and evaluated according to. The results are shown in Tables 4 to 6 below.

(A) Shear adhesive strength at 200 ° C. Two steel plates having a width of 10 mm, a length of 150 mm and a thickness of 1.0 mm were preheated at 200 ° C. and then lapped for 5 mm and bonded with this resin composition. Next, this is 200 ℃ × 20
It was held for curing for a minute to prepare a shear adhesive strength test piece.
Then, the shear adhesive strength of this test piece in a 200 ° C. atmosphere was measured.

(B) Heat resistance The test piece prepared by the above shear adhesive strength test was left in an atmosphere of 200 ° C. for 1200 hours, then cooled to room temperature, and the shear adhesive strength was measured to give a ratio% to the initial shear adhesive strength. ).

(C) Gap filling ratio Two spacers having a thickness of 0.5 mm were sandwiched between two steel plates having a width of 10 mm, a length of 150 mm and a thickness of 1.0 mm, at intervals of 10 mm, and the steel plates were heated. Then, 200
When the temperature reached ℃, the resin composition was sprinkled into the slit-shaped gap formed between both steel plates and the spacer, and the melt was poured. After that, hold at 200 ° C. for 20 minutes to cure, cool to room temperature, then measure the shear adhesive strength,
The ratio (%) to the initial shear adhesive strength obtained in (b) above is shown.

(D) Crack occurrence rate The resin composition was heated to 200 ° C. and 80 mm × 20 m.
A molded product of m × 5 mm in thickness was prepared, and was cooled to room temperature 20 minutes after the start of heating. Then, after cooling, the number of samples in which a crack was generated inside the cured product of the resin composition within 24 hours was shown as a ratio to the total number of measurement samples.

(E) Blocking resistance The resin composition is stored in a constant temperature and constant humidity chamber set at a temperature of 40 ° C. and a humidity of 80%, and after 500 hours from the start of storage, the powder state of the resin composition is the same as before storage. Was investigated.

[0056]

[Table 4]

[0057]

[Table 5]

[0058]

[Table 6]

From the results of Tables 4 to 6 above, the comparative example products have low shear adhesive strength, heat resistance, gap filling ratio, and crack generation ratio. On the other hand, the example products obtained favorable values for all the test results. From this,
It can be seen that the example products are excellent in both heat resistance and impregnation property.

Claims (2)

[Claims] 1. An epoxy resin composition comprising the following components (A) to (C). (A) An epoxy resin represented by the following general formula (1). [Chemical 1] [In the above formula (1), R is H or a lower alkyl group. ] (B) A tetrafunctional epoxy resin represented by the following general formula (2). [Chemical 2] (C) Hardener. 2. An epoxy resin composition comprising a curing accelerator in addition to the components (A) to (C) according to claim 1.