JPS58187465A - Epoxy resin composition for powder paint having flexibility - Google Patents

Abstract

PURPOSE:The titled composition useful for coating the outer face of steel pipe, etc., having improved adhesivity and corrosion resistance, and resistance to water, acid, and alkali, comprising a bisphenol type epoxy resin having a specific number of epoxy equivalent and a diglycidyl ester of a fatty dicarboxylic acid. CONSTITUTION:(A) 20-90pts.wt. bisphenol type epoxy resin (e.g., bisphenol A type diglycidyl ester-based epoxy resin) having 400-2,500 epoxy equivalents is blended with (B) 80-10pts.wt. diglycidyl ester of 10-25C fatty dicarboxylic acid obtained from (i) a fatty dicarboxylic acid (e.g., diglycidyl decanedioate) and (ii) epichlorohydrin, to give the desired composition. EFFECT:Having improved alkali resistance. USE:For coating steel bar, and for electrical insulating coating compound.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel epoxy resin composition for powder coatings which has excellent =I flexibility, adhesion and anti-corrosion performance.

Due to its excellent performance, epoxy resin is used in various applications such as paint, electrical appliances, and adhesives, but it is particularly used in paints. In paint applications, the demand for powder paints has been increasing in recent years due to the growing need for low pollution and resource conservation.

This powder coating is usually obtained by heating a resin component, #A material, and other additives, melting and kneading them using an extruder, cooling the mixture, and pulverizing the resulting solid material. Therefore, as a resin component to be used.

Resins that have good anti-blocking properties and low melt viscosity at storage temperatures (usually room temperature) are desirable. Resins that meet these requirements include thermosetting resins such as epoxy resins and polyester resins, and hot-mouth plastic resins such as vinyl chloride resins and polyethylene, but epoxy resins are used for applications that require corrosion resistance. It will be done. In applications that require corrosion resistance, there has recently been a demand for coatings that have excellent bending workability and impact strength at normal humidity or at low temperatures of about 120 degrees Celsius, and conventional epoxy threads have been used. It has become impossible to deal with the problem with paint.

The present inventors have made extensive studies on epoxy resins for powder coatings that can overcome these drawbacks, that is, have both corrosion resistance and flexibility, and as a result, they have discovered the present invention.

That is, the present invention provides (At epoxy equivalent is VOθ~2jθ
The flexibility obtained by mixing 90 parts by weight of bisphenol-type EBOKI V-fatty θ, which is θ, and (Bl carbon number / diglycidyl ether of aliphatic dicarboxylic acid with θ ~ 2j / θ ~ lθ overlapped part) This is an epoxy resin composition for powder coatings.

The epoxy resin used in the present invention is a compound having an average of 2 epoxy groups in the molecule, and a typical example is a condensate of epichlorohydrin and a bisphenol compound. In this case, the bisphenol compound is, for example, +2.2'-bis(
¥, ¥'-hydroxyphenyl) furopane (commonly known as bisphenol), halogenated bisphenol -2,2'
-bis(da,y'-hydroxyphenyl)methane (commonly known as bisphenol F), 2.2'-□bis(4t,
Da'-human autoxyphenyl) sulfone (commonly known as bisphenol S) can be mentioned. Preferably, it is a hisphenol A type diglycidyl ether type Evoquin resin, and in order to use it as a powder coating, the epoxy equivalent is O.
O~2jOθ is preferable. Such epoxy resins include the product name AgRJ Otsu/manufactured by Asahi Kasei Corporation.
(Epoxy equivalent gain θ~jOθ).

AERIA4t (epoxy equivalent de θθ~/θθθ).

A13Rjt<7 (epoxy equivalent/730~.2/jθ
), etc.

If the epoxy equivalent is less than 2000, the anti-blocking property as a powder coating is poor and it is not practical, and if the epoxy equivalent is more than 2 soo, the powder has poor flowability during baking and does not form a good coated surface.

The diglycidyl ester of aliphatic dicarboxylic acid used in the present invention is obtained from an aliphatic dicarboxylic acid having a carbon number of /θ to 2j and epichlorohydrin. Examples of aliphatic dicarboxylic acids include diglycidyl decanedioate, diglycidyl undecanedioate, diglycidyl dodecanedioate, diglycidyl tetradecanedioate, diglycidyl pentadecanedioate, i
/Diglycidyl esters of linear aliphatic dicarboxylic acids such as diglycidyl butadecanedioate and diglycidyl dodecanedioate, and branched chains such as diglycidyl (3-methyldecane)dioate and diglycidyl (dimethylundecane)dioate. The diglycidyl esters of aliphatic dicarboxylic acids can be made into fists. Preferably, the number of carbon atoms is 20/glue. If the number of carbon atoms is 9 or less, the flexibility will be less than 1 minute, and if the number of carbon atoms is 2 or more, the chemical resistance will be less than 1 minute.

It has the disadvantage of low surface hardness.

The composition of the present invention has a weight ratio of the prisoner component/component (B) of θ/
It is in the range of fθ to 9θ/10, and may be selected depending on the purpose.

The method for obtaining the composition of the present invention is not particularly limited, and it can be obtained by any of the commonly used methods such as melt blending, dry blending, and semi-dry blending.

In the present invention, the curing agent is not particularly limited, and skewers can be made using commonly used curing agents, such as novolak type phenolic resin, dicyandiamide, imidazoles, hydrazides, aromatic amines, acid anhydrides, etc.

According to the invention, the addition of extenders, flow control agents, reinforcing agents, fillers and pigments is possible. Examples of these additives include glass fibers, asbestos fibers, carbon fibers, polyethylene powder 1 quartz powder, mineral silicates 1 e.g. mica,
Asbestos powder and slate powder, kaolin, aluminum oxide, aluminum hydroxide, antimony trioxide, silica, titanium dioxide, carbon black, oxide color pigments.

Examples include metal powder, polyester resin, acrylic resin, and the like.

The coating film using the composition of the present invention exhibits good i'I flexibility, adhesion, and excellent corrosion resistance, and has water resistance, acid resistance,
It also has good alkali resistance.

The use of the resin composition according to the present invention is not particularly limited, and can be applied to a wide range of uses such as external coating of steel pipes and electrical insulation coating for steel bars.

The present invention will now be explained in more detail with reference to Examples. In the examples, unless otherwise specified, parts represent parts by weight.

Example/~Bisphenol A type epoxy resin A, E, R, -664t (Asahi Kasei Co., Ltd. Tai; trade name) with 19jθ per guepoxy and diglycidyl ester of saturated aliphatic dicarboxylic acid with carbon number/l are shown in Table-/ A powder coating was prepared by blending dianediamide and comethylimidazole as an accelerator, and the film performance was examined by baking at 1θ°C/2θ minutes. The results are shown in Table-/.

(The following is a blank space) Comparative Example/In the same manner as in Example/, a paint was made with the formulation shown below, and the film characteristics were examined.

Blend AER-j≦G 700 parts Dicyandiamide 9 parts Co-methylimidazole 0.2 parts Film property elongation 4A j Tensile strength jwwJ Example j, Comparative example λ The lkM obtained in Example 3 and Comparative example/ is -20 The performance at ℃ was investigated. The results are shown below.

Example 3 Comparative Example - Coating film performance at 20°C Bendability λ゛ake / θ■ e or more DuPont Togeki jOtx or less L 10 om (O θ0 f x 0 inches) Examples 6, 7 A, W, R , −, < j 4t and diglycidyl ester of saturated aliphatic dicarboxylic acid having carbon number/θ and coj are mixed in a weight ratio of O θ/Da θ, and powdered using anhydrous trimeric acid) M as a hardening agent. A body paint was prepared and a coating film was obtained by baking at 20θ°C for 10 minutes. The coating performance of the obtained coating film at θ°C was investigated. The results are shown in Table-2.

Claims (1)

[Claims] Epoxy 5 - 0 to 90 parts by weight of a bisphenol-type epoxy resin having a ratio of 0 to 23 θθ and (B) diglycidyl varnish of an aliphatic dicarboxylic acid having carbon number/θ to 2j! Flexible epoxy resin composition for powder coatings prepared by mixing 0 to 10 parts by weight