JPH06136092A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To provide an epoxy resin composition containing two kinds of diglycidyl ether compounds having specific structures as an epoxy resin, highly improved in weather resistance, and suitable for outdoor coatings, LED-sealing resins loaded on automobiles, etc. CONSTITUTION:The epoxy resin composition contains (A) an epoxy resin comprising the mixture of 1,4-cyclohexanedimethanol diglycidyl ether (DME) and hydrogenated bisphenol A diglycidyl ether (HBE). The DME and HBE in the component A is preferably mixed in a DME/HBE weight ratio of 30/70 to 60/40. The component B is preferably an aliphatic polyamine curing agent such as ethylene diamine when the ordinary temperature curing reactivity is required for outside coatings, and is also preferably an acid anhydride curing agent such as phthalic acid anhydride when used for sealing light emitting diodes, etc.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition, and more particularly to an epoxy resin composition having excellent weather resistance.

[0002]

2. Description of the Related Art Epoxy resin compositions are generally known to have excellent mechanical and electrical properties, as well as good adhesiveness, solvent resistance, water resistance, heat resistance, etc. Widely used in insulation materials, adhesives, paints, civil engineering and construction. Diglycidyl ether of bisphenol A (hereinafter abbreviated as "DGEBA") has been widely used as an epoxy resin which is a main component of such a composition.

In recent years, light emitting diodes encapsulated with an epoxy resin composition have been used for automobiles and for outdoor displays, while in the paint field, epoxy resin compositions have been used for corrosion protection of outdoor storage tanks and pipes. There is a direction to be.

Although DGEBA has excellent physical properties peculiar to epoxy resins, there is room for improvement in weather resistance. For the purpose of eliminating such drawbacks, addition of an ultraviolet absorber, a light stabilizer, or the like, or replacement with hydrogenated bisphenol A diglycidyl ether or an alicyclic epoxy resin has been carried out.

[0005]

However, when a general-purpose DGEBA-containing cured product containing an ultraviolet absorber, a light stabilizer, etc. is left outdoors, discoloration and deterioration of gloss are suppressed in the short term. However, due to long-term exposure, it loses its efficacy due to decomposition, volatilization, elution due to rainfall, etc., causing remarkable yellowing and a decrease in gloss due to chalking.

On the other hand, when hydrogenated bisphenol A diglycidyl ether is used, yellowing due to ultraviolet rays hardly occurs, but the gloss gradually decreases with long-term outdoor exposure.

When an alicyclic epoxy resin is used, the cured product is significantly inferior in crack resistance and the cyclohexene skeleton remaining in the resin causes yellowing due to ultraviolet rays. Therefore, it has been strongly desired to develop a formulation that improves the weather resistance without deteriorating the cured physical properties of the epoxy resin composition.

An object of the present invention is to provide a novel and useful epoxy resin composition having improved weather resistance, which is particularly suitable for outdoor coatings and LED sealing resins for outdoor and automobile mounting.

[0009]

Means for Solving the Problems As a result of intensive studies to solve such a drawback, the present inventors have found that a cured product can be obtained by selectively using two kinds of diglycidyl ethers having a specific structure as an epoxy resin. It has been found that the weather resistance is remarkably improved, and the present invention has been completed based on such findings.

That is, the epoxy resin composition according to the present invention is a composition which contains an epoxy resin and a curing agent and is liquid at room temperature, wherein the epoxy resin is 1,4-cyclohexanedimethanol diglycidyl ether (hereinafter abbreviated as "DME"). And hydrogenated bisphenol A diglycidyl ether (hereinafter abbreviated as “HBE”).

The mixing ratio of the epoxy resin component is not particularly limited as long as the predetermined effects of the present invention can be obtained, but usually DME / HBE (weight ratio) = 20/8.
It is 0 to 80/20, preferably 30/70 to 60/40.

When DME is not used, the gloss of the surface of the cured product is deteriorated by long-term outdoor exposure, while H
When BE is not used, the cured product has insufficient heat resistance, mechanical properties, moisture resistance and the like, which is not practical and causes remarkable chalking due to long-term outdoor exposure.

Further, the epoxy resin composition according to the present invention includes alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidyl ether type epoxy resin of long-chain polyol, dihydric phenol such as bisphenol A and bisphenol F, and epichlorohydrin. Bisphenol type epoxy resin, novolac type epoxy resin,
A resin component such as a polyolefin-type epoxy resin and an epoxy compound such as a relatively low-viscosity reactive diluent such as monoepoxide or polyepoxide can be appropriately blended within a range that does not adversely affect the predetermined effects of the present invention. .

As the curing agent according to the present invention, a polyamine or an acid anhydride is mainly used, and a compound known so far (for example, Hiroshi Kakiuchi, "New Epoxy Resin", page 164, (stock) ) Shokoido, 1985) is not particularly limited as long as it can form an epoxy resin composition which is liquid at room temperature.

Such a curing agent is appropriately selected according to the application. For example, for outdoor coating, an aliphatic polyamine curing agent is suitable especially when room temperature curing reactivity is required, while a light emitting diode is used. An acid anhydride-based curing agent is used when heat curing is possible, such as in sealing, and where higher heat resistance and mechanical, electrical, or optical characteristics are required.

Specific examples of the polyamine-based curing agent include ethylenediamine, tetramethylenediamine, hexamethylenediamine, diethylenetriamine, iminobispropylamine, bis (hexamethylene) triamine, triethylenetetramine, tetraethylenepentamine and pentaethylene. Hexamine, 1,3,6-trisaminomethylhexane, N-benzylethylenediamine,
Trimethylhexamethylenediamine, dimethylaminopropylamine, diethylaminopropylamine, aminoethylethanolamine, diethylene glycol / bispropylenediamine, menthenediamine, isophoronediamine,

N-aminoethylpiperazine, diaminodicyclohexylmethane, bis (4-amino-3-methylcyclohexyl) methane, 1,3-bis (aminomethyl) cyclohexane, 3,9-bis (3-aminopropyl) -2 , 4,8,10-Tetraoxaspiro [5,
5] Undecane and mixtures thereof, carboxylic acids,
Examples include modified products of epoxy compounds, methyl methacrylate, phenol / formaldehyde, acrylonitrile and the like.

The blending amount of the polyamine-based curing agent is not particularly limited as long as a predetermined effect is obtained, but usually, the equivalent ratio of active hydrogen in the curing agent to the epoxy group is 0.5 to 1.2. , Preferably about 0.7 to 1.0.

Specific examples of the acid anhydride-based curing agent include:
Hexahydrophthalic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, methylanhydride Nadesic acid, dodecenyl succinic anhydride, Diels-Alder reaction products of decatrienes such as α-terpinene and alloocimene and maleic anhydride, and hydrogenated products thereof, structural isomers or geometric isomers, and their mixed modifications are It is illustrated.

The amount of the acid anhydride-based curing agent to be compounded is not particularly limited as long as a predetermined effect can be obtained, but usually, the equivalent ratio of the acid anhydride group to the epoxy group is 0.7 to 1.2, preferably 0. It is about 8 to 1.1.

If desired, the curing agent according to the present invention may be used in combination with a curing accelerator. As such a curing accelerator, conventionally known compounds, for example, tertiary amines such as benzyldimethylamine, tris (dimethylaminomethyl) phenol, and dimethylcyclohexylamine; 2-ethyl-4-methylimidazole, 2-methylimidazole, Imidazoles such as 1-benzyl-2-methylimidazole; diazabicycloalkenes such as 1,8-diazabicyclo (5,4,0) undecene-7 and salts thereof, zinc octylate, tin octylate and aluminum acetylacetone. Organometallic compounds such as complexes;

Quaternary ammonium compounds; organic phosphorus compounds such as triphenylphosphine and triphenyl phosphite; boron compounds such as boron trifluoride and triphenylborate; metal halogens such as zinc chloride and stannic chloride. Compounds are listed.

The compounding amount of the curing accelerator can be appropriately selected depending on the kind of the curing agent.
Usually, 0.01 to 10 parts by weight is used with respect to 0 parts by weight.

The curing accelerator can be applied as a constituent of the curing agent composition, or can be blended with other additives when preparing the epoxy resin composition.

Examples of such other additives include plasticizers, dyes, pigments, release agents, antioxidants, ultraviolet absorbers, light stabilizers, flame retardants, fillers, leveling agents, defoaming agents, anti-sag agents. , Various additives such as solvents and base materials are exemplified, and the application amount thereof, unless adversely affecting the predetermined effects of the present invention,
It is not particularly limited.

The epoxy resin composition thus obtained is
When using a polyamine-based curing agent, it is particularly useful as a weather-resistant anticorrosion coating for storage tanks and pipes used outdoors, and when using an acid anhydride-based curing agent, it is suitable for use in automobiles and It is particularly useful as a weather-resistant sealing material for light-emitting diodes for outdoor display.

[0027]

EXAMPLES The present invention will be described in detail below with reference to Examples and Comparative Examples. The properties of the epoxy resin composition obtained in each example were measured and evaluated by the following methods.

Glass transition temperature : A sample cut out from a cured product is measured using a differential scanning calorimeter (manufactured by Shimadzu Corporation, DSC-30).

Rockwell hardness (M scale) : JIS K-
Measure according to 6911.

Charpy impact strength : Measured according to JIS K-6911.

Accelerated weather resistance test : A weatherometer (manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used, and a xenon burner of 0.39 wa was used.
tt / cm ² , black panel temperature 63 ° C, humidity 60% R.
H., 18 minutes of water spraying / 120 minutes, the following evaluation is performed on the test piece exposed for a predetermined time.

Gloss retention : Thickness 0.7 created on steel plate
About 0.8 mm coating film, the surface gloss after accelerated weathering test is measured by gloss meter (GM-Murakami Color Research Laboratory, GM-
It is measured according to 3) and is represented by the retention rate with respect to the surface gloss before the accelerated weather resistance test.

Light transmittance : With respect to a plate-like test piece having a thickness of 5 mm, which was cured by using an iron mold whose inner surface was mirror-finished, the light transmittance (wavelength 400 nm) before and after the accelerated weathering test was measured according to JIS K-
Measure according to 7105.

Example 1 As an epoxy resin, HBE (epoxy equivalent 215),
DME (epoxy equivalent 155), N-benzylethylenediamine as a polyamine curing agent, rutile titanium oxide as another additive, CAB551-0.2 (EAST
Manufactured by MAN CHEMICAL, cellulose butyrate acetate), toluene,
Butyl acetate, isopropanol, KS-603 (Shin-Etsu Silicone Co., Ltd., silicone defoamer), Seesor
b100 (manufactured by Cipro Kasei Co., Ltd., benzophenone-based ultraviolet absorber) and Sanol LS-770 (manufactured by Ciba-Geigy, hindered amine-based light stabilizer) were mixed in predetermined amounts to prepare an epoxy resin composition. The gloss retention rate under the accelerated weather resistance test was measured for the coating film obtained by curing this under the condition of 25 ° C. × 7 days. The results obtained are shown in Table 1.

Example 2 By changing the compounding ratio of the epoxy resin, a coating film was prepared without using an ultraviolet absorber or a light stabilizer, and the gloss retention rate was measured. The results obtained are shown in Table 1.

Comparative Examples 1 to 2 In Example 1, the gloss retention of the composition obtained without blending DME or HBE was measured. The results obtained are shown in Table 1.

Comparative Example 3 In Example 1, the gloss retention was measured when DGEBA (epoxy equivalent 188) was used instead of HBE.
The results obtained are shown in Table 1.

[Table 1]

Example 3 HBE, DME and ERL-422 as epoxy resins
1 (UCC, alicyclic epoxy resin, epoxy equivalent 1
41), RIKACID MH (produced by Shin Nippon Rika Co., Ltd., 4-methylhexahydrophthalic anhydride) as an acid anhydride curing agent, and Ucat SA102 (produced by San Apro Co., Ltd., 1,8-diazabicyclo ( 5,4,0) Undecene-7 2-ethylhexanoate) was mixed in a predetermined amount to prepare an epoxy resin composition. This one 100
The glass transition temperature, the Rockwell hardness, the Charpy impact strength, the light transmittance and the appearance under the accelerated weather resistance test of the cured product cured under the conditions of ℃ × 3h + 130 ℃ × 3h were measured. The results obtained are shown in Table 2.

Comparative Examples 4 to 6 In Example 3, the physical properties of the cured product without DME or HBE were evaluated. The results obtained are shown in Table 2.

Comparative Example 7 In Example 3, the physical properties of the cured product were evaluated when DGEBA was used instead of HBE. The results obtained are shown in Table 2.

[Table 2]

[0041]

The epoxy resin composition according to the present invention can suppress the yellowing of the cured product due to exposure to ultraviolet rays and the reduction of the surface gloss due to chalking. As a result, the cured product has heat resistance, mechanical properties, moisture resistance and the like. It is possible to significantly improve the weather resistance without deteriorating the various characteristics.

[Procedure amendment]

[Submission date] October 7, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

An object of the present invention, weather resistance is improved, especially <br/> to provide novel useful epoxy resin compositions suitable for LED encapsulation resins for outdoor paints and outdoor, automotive mounted is there.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

Example 2 A coating film was prepared by changing the compounding ratio of the epoxy resin and using no ultraviolet absorber or light stabilizer, and the gloss retention rate was measured. The results obtained are shown in Table 1 .

Claims (1)

[Claims] 1. In an epoxy resin composition which is liquid at room temperature and contains an epoxy resin and a curing agent, the epoxy resin is 1,
An epoxy resin composition, which is a mixture of 4-cyclohexanedimethanol diglycidyl ether and hydrogenated bisphenol A diglycidyl ether.