JP3339083B2 - Epoxy resin composition - Google Patents

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, and more particularly to an epoxy resin composition having excellent weather resistance.

[0002]

2. Description of the Related Art In general, epoxy resin compositions are known to have excellent mechanical and electrical properties and good adhesiveness, solvent resistance, water resistance, heat resistance and the like. Widely used for insulating 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 sealed with an epoxy resin composition have been used for mounting on automobiles and for outdoor displays, while in the field of paints, epoxy resin compositions have been used for corrosion protection of outdoor storage tanks and pipes. In the direction that will be.

[0004] Although DGEBA has excellent physical properties unique to epoxy resins, there is room for improvement in weather resistance. For the purpose of resolving such drawbacks, addition of an ultraviolet absorber, a light stabilizer, and the like, and replacement with hydrogenated bisphenol A diglycidyl ether and an alicyclic epoxy resin have been performed.

[0005]

However, when a general-purpose DGEBA-containing cured product to which an ultraviolet absorber or a light stabilizer is added is left outdoors, discoloration and a decrease in gloss are suppressed in a short term. However, after long-term exposure, its efficacy is lost due to decomposition, volatilization, elution by rainfall, etc., causing significant yellow discoloration and reduction in gloss due to chalking.

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

When an alicyclic epoxy resin is used, crack resistance of the cured product is remarkably deteriorated, and yellow discoloration due to ultraviolet rays is caused by a cyclohexene skeleton remaining in the resin. For this reason, there has been a strong demand for the development of a formulation for improving the weather resistance without lowering the cured physical properties of the epoxy resin composition.

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.

[0009]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned drawbacks, and as a result, by selectively using and using two kinds of diglycidyl ethers having a specific structure as an epoxy resin, the cured product is obtained. The inventors have found that the weather resistance is significantly improved, and have completed the present invention based on such findings.

That is, the epoxy resin composition according to the present invention is a liquid composition at room temperature containing an epoxy resin and a curing agent, 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 effect of the present invention can be obtained, but usually, DME / HBE (weight ratio) = 20/8.
It is 0-80 / 20, preferably 30 / 70-60 / 40.

When DME is not used, long-term outdoor exposure causes a decrease in gloss of the surface of the cured product.
When BE is not used, the heat resistance, mechanical properties, moisture resistance, and the like of the cured product become insufficient, which makes practical use difficult. In addition, prolonged outdoor exposure causes significant choking.

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

As the curing agent according to the present invention, polyamines or acid anhydrides are mainly used, and compounds known so far (for example, edited by Hiroshi Kakiuchi, "New Epoxy Resin", p. 164, KK ), Is not particularly limited as long as it can form a liquid epoxy resin composition at room temperature.

The curing agent is appropriately selected depending on the application. For example, for outdoor paints, particularly when room temperature curing reactivity is required, an aliphatic polyamine-based curing agent is suitable. An acid anhydride-based curing agent is used when heat curing is possible such as sealing, and higher heat resistance and higher mechanical, electrical and optical properties are required.

Specific examples of the polyamine 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, mensendiamine, 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,
Modified products such as epoxy compounds, methyl methacrylate, phenol / formaldehyde, and acrylonitrile are exemplified.

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.

As the acid anhydride-based curing agent, specifically,
Hexahydrophthalic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, 3-methylhexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, 3-methyltetrahydrophthalic anhydride, 4-methyltetrahydrophthalic anhydride, methyl anhydride Nailsic acid, dodecenyl succinic anhydride, Diels-Alder reaction product of decatriene such as α-terpinene and allocymene with maleic anhydride and their hydrogenated products, structural isomers or geometric isomers, and mixed modified products thereof. Is exemplified.

The compounding amount of the acid anhydride-based curing agent is not particularly limited as long as a predetermined effect is obtained, but the equivalent ratio of the acid anhydride group to the epoxy group is usually 0.7 to 1.2, preferably 0 to 1.2. 0.8 to 1.1.

The curing agent according to the present invention may optionally use a curing accelerator. Examples of such curing accelerators include 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 triphenyl borate; metal halogens such as zinc chloride and stannic chloride; And the like.

The amount of the curing accelerator can be appropriately selected depending on the type of the curing agent.
Usually, about 0.01 to 10 parts by weight is used per 0 parts by weight.

The curing accelerator can be used as a component of the curing agent composition, or can be added together with other additives when preparing the epoxy resin composition.

Such other additives include plasticizers, dyes, pigments, release agents, antioxidants, ultraviolet absorbers, light stabilizers, flame retardants, fillers, leveling agents, defoamers, anti-sagging agents. Examples include various additives and base materials such as solvents, and the amount of the additive is not adversely affected as long as the predetermined effect of the present invention is not adversely affected.
There is no particular limitation.

The epoxy resin composition thus obtained is
When a polyamine-based curing agent is used, it is particularly useful as a weather-resistant paint for storage tanks and pipes used outdoors. It is particularly useful as a weather-resistant sealing material for light-emitting diodes for outdoor display.

[0027]

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 from a cured product is measured using a differential scanning calorimeter (DSC-30, manufactured by Shimadzu Corporation).

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

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

Accelerated weathering test : Using a weatherometer (manufactured by Toyo Seiki Seisaku-sho, Ltd.), a xenon burner 0.39 wa
tt / cm ² , black panel temperature 63 ° C, humidity 60% R.
H. The following evaluation is performed on the test piece exposed for a predetermined time under the condition of watering for 18 minutes / 120 minutes.

Gloss retention : thickness 0.7 formed on steel plate
The surface gloss after the accelerated weathering test for a coating film of ~ 0.8 mm was measured using a gloss meter (manufactured by Murakami Color Research Laboratory Co., Ltd., GM-
3) and is expressed as a retention rate with respect to the surface gloss before the accelerated weathering test.

Light transmittance : The transmittance of light (wavelength 400 nm) before and after the accelerated weathering test was measured for a 5 mm-thick plate-shaped test piece cured using an iron mold with a mirror-finished inner surface.
Measure according to 7105.

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

Example 2 A coating film was prepared without changing the blending ratio of the epoxy resin and using an ultraviolet absorber or a light stabilizer, and the gloss retention was measured. Table 1 shows the obtained results.

Comparative Examples 1 and 2 In Example 1, the gloss retention of the composition obtained without blending DME or HBE was measured. Table 1 shows the obtained results.

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

[Table 1]

Example 3 HBE, DME and ERL-422 as epoxy resins
1 (UCC, alicyclic epoxy resin, epoxy equivalent 1
41), Ricacid MH (4-methylhexahydrophthalic anhydride, manufactured by Shin Nippon Rika Co., Ltd.) as an acid anhydride-based curing agent, and Ucat SA102 (1,8-diazabicyclo (manufactured by San Apro Co., Ltd.) as a curing accelerator. 5,4,0) undecene-7 2-ethylhexanoate) was blended in a predetermined amount to prepare an epoxy resin composition. 100 of this
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 (° C. × 3 h + 130 ° C. × 3 h) were measured. Table 2 shows the obtained results.

Comparative Examples 4 to 6 In Example 3, the physical properties of the cured product when DME or HBE was not added were evaluated. Table 2 shows the obtained results.

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

[Table 2]

[0041]

The epoxy resin composition according to the present invention can suppress yellowing of the cured product due to exposure to ultraviolet rays and decrease in surface gloss due to chalking, resulting in heat resistance, mechanical properties, moisture resistance, etc. of the cured product. It is possible to remarkably improve the weather resistance without impairing the characteristics of the above.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-2-215824 (JP, A) JP-A-2-296820 (JP, A) JP-A-56-76448 (JP, A) JP-A-58- 214225 (JP, A) JP-A-56-135517 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 59/24 C08L 63/00-63/10

Claims (1)

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