JP2799401B2 - Epoxy resin composition for paint - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high solid type paint composition and a composition for water-based paint aiming at low pollution.

"Prior art" The coating of a metal plate, for example, on the inner and outer surfaces of a can for cans and soft drinks, a bisphenol A-type epoxy resin having a number average molecular weight of 900 to 10,000 is usually formed using an amino resin or a phenol resin as a crosslinking agent. % To 80% of an organic solvent. With regard to metal cans, various types of can molds have been made, and paints used are required to have high workability because of severe workability. In addition, since the inner surface of the can is in contact with the contents for a long period of time, the adhesion to metal materials is also important.
Bisphenol A type epoxy resins having a high molecular weight of 00 to 3800 or more are widely used. However, in recent years, technological conversion has been desired from the viewpoint of resource saving, energy saving, environmental pollution, and the like.

The volatile organic solvent content of a high solid type paint or a water-based paint is usually 5% to 40%, but for a high molecular weight bisphenol A type epoxy resin, the solvent amount is 40%.
When the amount is reduced to below, the viscosity becomes high and satisfactory solution performance cannot be obtained, and there is a problem that when a low molecular weight epoxy resin is used to reduce the amount of the solvent to 40% or less, processability is inferior. Also, even when using a bisphenol F type epoxy resin having a lower viscosity than the bisphenol A type epoxy resin,
Although the amount of the solvent can be reduced, there is a problem that the processability is poor.

Furthermore, regarding the water-based paint for metal cans, a transition to a water-dispersed paint based on a high-molecular-weight epoxy resin has been studied, but the water-based paint based on a bisphenol A-type epoxy resin has been studied. Contains 10% to 18 organic solvents
%, And the organic solvent containing water must be distilled off at low temperature and reduced pressure in order to reduce this organic solvent.

"Problems to be Solved by the Invention" Under the above-mentioned circumstances, the present invention provides a high-solid type paint or a water-based paint which is a low-viscosity epoxy resin and excellent in adhesion and processability.

"Means and Actions for Solving the Problems" The present invention relates to a coating composition comprising a bisphenol-type epoxy resin and a curing agent component, wherein 5% to 100% of the bisphenol skeleton of the epoxy resin has a bisphenol F skeleton. And the binuclear purity in the components of bisphenol F epoxy resin and bisphenol F is
The present invention relates to an epoxy resin composition for coatings, which is manufactured using a composition comprising at least 96% and has a number average molecular weight of at least 900.

The bisphenol-type epoxy resin used in the present invention is bis (4-hydroxyphenyl) methane diglycidyl ether obtained from bis (4-hydroxyphenyl) methane (commonly called bisphenol F) and epihalohydrin and bis (4-hydroxyphenyl) propane (Commonly known as bisphenol A), or an addition polymer of bis (4-hydroxyphenyl) propane diglycidyl ether obtained from bisphenol A and epihalohydrin and bisphenol F, or bis (4-hydroxyphenyl) methane diglycidyl The number average molecular weight of an addition polymer of ether and bisphenol F is 900 or more, and the bisphenol F skeleton in one molecule is 5% or more.
Contains 100%.

The present invention blends bisphenol F and epihalohydrin or a low molecular weight epoxy resin obtained by condensing bisphenol A and epihalohydrin in the presence of an alkali metal catalyst or an alkaline earth metal catalyst at an arbitrary weight ratio, Bisphenol A and / or bisphenol F can be reacted at 50 to 200 ° C. with any of the catalysts conventionally used in this type of polyaddition reaction, such as alkali metal or alkaline earth metal compounds and various amines. The production can be carried out by selecting a condition at which the number average molecular weight is 900 or more from among the temperature and 20 minutes to 20 hours and performing a polyaddition reaction.

In the present invention, as described above, 5% to 100%, preferably 20% to 100% of the bisphenol skeleton of the epoxy resin.
It is important that the% is a bisphenol F skeleton in order to achieve the object of the present invention, and if it is 5% or less, no improvement in low viscosity is observed.

In order to achieve the object of the present invention, it is also important that the binuclear purity of the components of the bisphenol F and the low molecular weight bisphenol F type epoxy resin used in the present invention is 96% or more, preferably 98% or more. If the purity is 96% or less, a reaction occurs in a branched manner at the time of the polymerization reaction, so that sufficient coating film performance cannot be obtained.

Bisphenol F with high binuclear purity can be increased to 96% or more by molecular distillation or recrystallization of bisphenol F (binuclear purity 85-95%), which is usually used for low-viscosity bisphenol type epoxy resin. Can be done. Further, as bisphenol F type epoxy resin having high binuclear purity, specifically, Epototo YDF-170 manufactured by Toto Kasei Co., Ltd.
(Epoxy equivalent 160-180g / eq, viscosity 2000-5000cps / 25
YDF-8170 (epoxy equivalent 150-170 g / eq, viscosity 800-
1500 cps / 25 ° C., binuclear purity 98 to 100%).

Examples of the curing agent component used in the present invention include a resol type or novolak type phenol resin, a melamine resin, and a urea resin. For aqueous coatings, aqueous aminoplast resins are preferable, and for example, hexamethoxymethylmelamine resin, methylolmelamine resin, methylolated urea resin, and the like can be used.

The compounding ratio of the bisphenol type epoxy resin to the above curing agent is preferably in the range of 95/5 to 50/50. Paratoluenesulfonic acid or a salt thereof or phosphoric acid may be added as a curing accelerator.

The epoxy resin composition for paints of the present invention is obtained by dissolving a bisphenol type epoxy resin and the curing agent resin in a solvent having a solid content of 25 to 40% in a lipophilic solvent or a lower alcohol solvent of the epoxy resin. A metal material such as a treated steel plate, a tin plate and an aluminum plate is coated by a known method such as spraying, roll coating and immersion so as to have a dry film thickness of 1 to 20 microns, particularly 5 to 15 microns.

The curing condition of the coating film can be selected from a baking temperature of 180 ° C. to 230 ° C. and a baking time of 3 minutes to 30 minutes.

The bisphenol-type epoxy resin of the present invention can be used in the form of a powder coating or a water-based coating obtained by a known method.

In the method of forming an aqueous coating, generally, an acrylic acid monomer using an arbitrary initiator is grafted to an epoxy resin and dispersed in an aqueous medium in the presence of a tertiary amine, or an arbitrary polymerization initiator is used. To produce a copolymer of four to four types of acrylic monomers, an epoxy resin modified with an organic acid having one arbitrary functional group is dispersed in an aqueous medium in the presence of a tertiary amine, etc. I have. The polymerization initiator used is preferably a compound that generates a radical, azobisisobutyronitrile or benzoyl peroxide. The acrylic monomer used is preferably acrylic acid, ethyl acrylate, ethyl methacrylate methacrylate, hydroxyethyl methacrylate, fumaric acid, or the like.

Hereinafter, the present invention will be described specifically with reference to Examples. Parts in the examples are parts by weight.

"Examples and Comparative Examples" Example 1-1 A bisphenol A type epoxy resin having an epoxy equivalent of 186.5 g / eq (Epototo manufactured by Toto Kasei Co., Ltd.) was placed in a reaction vessel equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas supply device. YD-128) Bisphenol F-type epoxy resin with 50 parts and epoxy equivalent of 158.3 g / eq, dinuclear substance purity 98.3% molecular distilled product
50 parts (Epototo YDF-8170 manufactured by Toto Kasei Co., Ltd.) 57 parts of bisphenol A and 0.1 part of a 10% aqueous sodium hydroxide solution are added and stirred, and the temperature is raised to 170 ° C. while passing a nitrogen gas. To obtain a high molecular weight epoxy resin. Table 1 shows the properties of this epoxy resin.

30.0 g of the above-mentioned epoxy resin 30.0 g of solvent naphtha,
An epoxy resin solution was prepared by dissolving in 23.0 g of cellosolve acetate and 13.0 g of ethylene glycol monobutyl ether. 80.0 g of this epoxy resin solution was used as a curing agent component as a resol type phenol resin, HITANOL 4010 (non-volatile content 50 wt%, viscosity A, GH method / 25 ° C., manufactured by Hitachi Chemical Co., Ltd.)
13.6 g and 85% phosphoric acid 0.2 g were mixed to obtain a coating material of Example 1-1.

Example 1-2 The above YD-128 10 was placed in the same reaction vessel as in Example 1-1.
0 parts, 42.6 parts of bisphenol F (binuclear purity 99.2%) molecularly distilled at a temperature of 180 ° C. and a degree of vacuum of 0.05 torr, and 0.1% of a 10% sodium hydroxide solution were added and stirred. Depending on the conditions, a high molecular weight epoxy resin was obtained. Table 1 shows the properties of this epoxy resin. Example 1 below
Preparation of an epoxy resin solution and preparation of a coating were performed in the same manner as in Example 1 to obtain a coating of Example 1-2.

Example 1-3 The same YDF-8170 was placed in the same reaction vessel as in Example 1-1.
100 parts, 57.9 parts of bisphenol A and 0.1 minute of a 10% aqueous solution of sodium hydroxide were added, and thereafter, a high-molecular-weight epoxy resin was obtained under the same conditions as in Example 1-1. Table 1 shows the properties of this epoxy resin. Thereafter, adjustment of the epoxy resin solution and preparation of a paint were carried out in the same manner as in Example 1-1, and Example 1-3 was performed.
Paint was obtained.

Example 1-4 The same YDF-8170 was placed in the same reaction vessel as in Example 1-1.
100 parts, 51.9 parts of the above-mentioned molecular-distilled bisphenol F, and 0.1 part of a 10% aqueous sodium hydroxide solution were added, and a high-molecular-weight epoxy resin was obtained under the same conditions as in Example 1-1. Table 1 shows the properties of this epoxy resin. Example 1-1 below
The preparation of the epoxy resin solution and the preparation of a paint were carried out in the same manner as in the above to obtain a paint of Example 1-4.

Comparative Example 1-1 The above YD-128 10 was placed in the same reaction vessel as in Example 1-1.
0 parts, 49.2 parts of bisphenol A, and 0.1 part of a 10% aqueous sodium hydroxide solution were added, and thereafter a high-molecular-weight epoxy resin was obtained under the same conditions as in Example 1-1. Table 1 shows the properties of this epoxy resin. Thereafter, epoxy preparation and coating were performed in the same manner as in Example 1-1 to obtain a coating of Comparative Example 1-1.

Comparative Example 1-2 Properties of Bisphenol A type epoxy resin, Epicoat 1007 manufactured by Yuka Shell Co., Ltd. are shown in Table 1. Thereafter, adjustment of the epoxy resin solution and preparation of a coating were performed in the same manner as in Example 1-1 to obtain a coating of Comparative Example 1-2.

Comparative Example 1-3 The same YDF-8170 was placed in the same reaction vessel as in Example 1-1.
100 parts, dinuclear substance purity 88% bisphenol F 50.6 parts, 10%
0.1 part of an aqueous solution of sodium hydroxide was added, and Example 1
Under the same conditions as in 1, a high molecular weight epoxy resin was obtained.
Table 1 shows the properties of this epoxy resin. Example 1 below
Preparation of an epoxy resin solution and preparation of a coating were performed in the same manner as in Preparation No.-1 to obtain a coating of Comparative Example 1-3.

Comparative Example 1-4 The same YDF-1701 was placed in the same reaction vessel as in Example 1-1.
Then, 00 parts, 55.3 parts of bisphenol A and 0.1 part of a 10% aqueous sodium hydroxide solution were added, and a high-molecular-weight epoxy resin was obtained under the same conditions as in the following examples. Table 1 shows the properties of this epoxy resin. Thereafter, adjustment of the epoxy resin solution and preparation of a coating were performed in the same manner as in Example 1-1 to obtain a coating of Comparative Example 1-4.

The coatings prepared in Examples and Comparative Examples were applied to an arosin-finished aluminum plate (0.3 × 50 × 200 mm) with a bar coater so as to have a dry coating of 10 μm, baked at 200 ° C. for 10 minutes, and then gel with chloroform. The fraction (solvent-insoluble content) was measured. Table 1 shows the results of the curing test.

Next, the coating materials prepared in Examples and Comparative Examples were applied to an arosin-finished aluminum plate (0.3 × 50 × 200 mm) with a bar coater so as to have a dry film thickness of 5 μm, and baked at 200 ° C. for 10 minutes. This test piece was subjected to a 1T bending process, and the energization current value (mA) when a voltage was applied to the processed portion was measured by an enamellator tester (manufactured by Nichia Instruments Inc.). Table 1 shows the results of the processing test.

Epoxy equivalent (g / eq): hydrochloric acid-dioxane method Softening point (° C.): ring and ball method Melt viscosity (GH): butyl carbitol 40% (resin)
Solution, Gardner-Holt method at 25 ° C Number average molecular weight (M
N), weight average molecular weight (MW), dispersion (MN / MW): GPC method GPC, Tosoh HLC-802A column; G-2000H, G-3000H, G-4000H polystyrene calibration curve Example 2 Example 1-2 The obtained epoxy resin (72 g) was charged into n-butanol (13.5 g) and butyl cellosolve (9.0 g) and dissolved by heating at 100 ° C., and then methacrylic acid (11.7 g), ethyl acrylate (0.2 g) and benzoyl peroxide (75%) 1.6 g were dissolved. The resulting monomer mixture was added dropwise at 115 to 119 ° C. over 2 hours, and the mixture was further stirred for 2 hours. Next, the mixture was cooled to 85 ° C., 9.0 g of dimethylethanolamine was added dropwise over 1 hour, and 232.9 g of ion-exchanged water was added dropwise at 50 ° C. over 1 hour to obtain an aqueous epoxy resin dispersion. This dispersion had a volatile organic solvent of 6.2% and a nonvolatile content of 28.
8%, water content 65%, pH 8.0, viscosity 450 cps / 25 ° C.

Comparative Example 2 The bisphenol A type epoxy resin obtained in Comparative Example 1-1 was reacted under the same conditions as in Example 2. However, after the addition of the monomer mixture, the viscosity increased, and stirring became impossible.

"Effect of the invention" The epoxy resin composition for coating of the present invention shown in the Examples,
Low viscosity and excellent workability compared to bisphenol A epoxy resin and bisphenol F epoxy resin synthesized using bisphenol F and bisphenol F epoxy resin having low binuclear purity shown in Comparative Examples It is possible to obtain a coating. Further, the content of the organic solvent can be easily reduced as the epoxy resin composition for a water-based paint.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C09D 163/00-163/10 C08G 59/20

Claims (1)

(57) [Claims] 1. A coating composition comprising a bisphenol type epoxy resin and a curing agent component, wherein 5% to 100% of the bisphenol skeleton of the epoxy resin is a bisphenol F skeleton, wherein the bisphenol F type epoxy resin and the bisphenol F The binuclear purity in the constituents of F is
An epoxy resin composition for a paint, wherein the epoxy resin composition has a number average molecular weight of 900 or more, which is produced using a composition comprising 96% or more.