JP2881984B2 - High solid paint composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel high-solid coating composition, and more particularly, to a high-solid coating composition containing a silicone compound in which a hydroxyl group is chemically bonded to a silicon atom and having excellent acid resistance and weather resistance. The present invention relates to a high solid coating composition.

[Prior art] In recent years, in the paint industry, there has been an increasing need for high solid type paints for the purpose of reducing organic solvent emissions due to problems such as environmental pollution, and also in terms of coating film performance, Due to the problem of deterioration of the coating film due to acid rain or the like, development of a coating material having excellent weather resistance and acid resistance is urgently required.

In general, in order to make a paint high solid, a low molecular weight base and a curing agent are used, and an attempt is also made to use a reactive diluent in combination. Usually, a relatively low molecular weight polyol is used as the base material, and a low molecular weight alkyl etherified melamine resin or an isocyanate compound is used as a curing agent, and a low molecular weight polyester compound is used as a reactive diluent. Often.

However, in the conventional high solid paint,
Because a low molecular weight base and curing agent are used,
There is a limit to the acid resistance of the coating film itself, and the use of a low molecular weight polyester compound as a reactive diluent also has the disadvantage that the coating film has insufficient weather resistance and acid resistance.

On the other hand, there is known a paint using a reaction product of a silicone compound in which a methoxy group is chemically bonded to a silicon atom and a diol compound (JP-A-60-168770). However, although this paint has relatively good weather resistance,
It has the disadvantage of poor acid resistance.

[Problems to be Solved by the Invention] Under such circumstances, the present invention has been made for the purpose of providing a high solid coating composition having excellent weather resistance and acid resistance.

[Means for Solving the Problems] The present inventors have conducted intensive studies to develop a high-solid coating composition having excellent weather resistance and acid resistance. Dramatically improve weather resistance, and a composition mainly composed of a resin mixture containing the resin, a hydroxyl group-containing resin and a curing agent having a specific functional group in a predetermined ratio, respectively, is suitable for the above purpose. The present inventors have found what can be done, and have completed the present invention based on this finding.

That is, the present invention relates to (A) a weight average molecular weight having two or more hydroxyl groups chemically bonded to a silicon atom per molecule.
5 to 50% by weight of a silicone compound having 200 to 4,000 and a hydroxyl equivalent of 100 to 600, and (B) 10 to 80% by weight of a hydroxyl group-containing resin
And (C) a curing agent 10 having a functional group capable of reacting with a hydroxyl group
The present invention provides a high solid coating composition containing a resin mixture of about 50% by weight as a main component.

 Hereinafter, the present invention will be described in detail.

The silicone compound (A) in the composition of the present invention has a hydroxyl group chemically bonded to a silicon atom in an amount of 2 per molecule.
Having a weight average molecular weight of 200 to 4.0
Those having a range of 00 and a hydroxyl equivalent in the range of 100 to 600 are used. If the number of hydroxyl groups chemically bonded to silicon atoms is less than 2 per molecule, the resulting coating film has a low crosslinking density, and the mechanical properties, particularly the impact resistance, are reduced.
On the other hand, if the weight average molecular weight is less than 200, the weather resistance of the coating film is insufficient, and if it exceeds 4,000, it becomes difficult to increase the solid content required for the high solid paint. Further, when the hydroxyl equivalent is less than 100, the mechanical properties of the coating film, particularly flexibility (for example, flex resistance) are poor, and when it exceeds 600, the weather resistance of the coating film tends to decrease.

Examples of the silicone compound used as the component (A) include KR-211, KR-212, KR-214, and KR-216.
[All are manufactured by Shin-Etsu Chemical Co., Ltd., trade names] and the like.

In the composition of the present invention, examples of the hydroxyl group-containing resin used as the component (B) include an acrylic resin, a polyester resin, an alkyd resin, an epoxy resin, a polyurethane resin, a fluororesin, and a silicone resin. One of these resins may be used, or two or more thereof may be used in combination within a range showing compatibility.

Further, in the composition of the present invention, examples of the curing agent having a functional group capable of reacting with a hydroxyl group used as the component (C) include an alkyl etherified melamine resin and an isocyanate compound. Among them, the alkyl etherified melamine resin is preferably one having an alkyl group of 8 or less and a number average molecular weight of 1,000 or less. If the carbon number of this alkyl group exceeds 8, there is a possibility that the water resistance of the obtained coating film is reduced, and if the number average molecular weight exceeds 1,000, it becomes difficult to highly solidify the paint,
Not preferred. As such alkyl etherified melamine resin, for example, as commercial products, Cymel 300, Cymel 301, Cymel 303, Cymel 350, Cymel 111
6, Cymel 1130, Cymel 1168 [all manufactured by American Cyanamid Co., Ltd., trade name], Nikarac MW-30, Nikarac MW-22A, Nikarac MX-40, Nikarac MX-45
[All are manufactured by Sanwa Chemical Co., Ltd., trade name], Regimin
730, Regimin 731, Regimin 735, Regimin 745, Regimin 746, Regimin 747, Regimin 753, Regimin 755, Regimin 764 [all manufactured by Monsanto, trade name], U-Van 120 [produced by Mitsui Toatsu Co., Ltd., trade name] , And the like.

In this case, an aromatic or aliphatic sulfonic acid compound can be used as a curing catalyst, but an aliphatic sulfonic acid compound is more preferable in terms of storage stability of a paint, appearance of a coating film, and the like.

Further, as the isocyanate compound, in one molecule,
Aromatic or aliphatic compounds having two or more isocyanate groups, such as 2,4-tolylene diisocyanate, 4,4 '
-Diphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, polyisocyanate compounds such as cyclohexane-1,4-diisocyanate, polyisocyanate compounds ethanol, alcohols such as hexanol, phenol, compounds having a phenolic hydroxyl group such as cresol, Blocked isocyanate compounds blocked with blocking agents such as oximes such as acetoxime and methyl ethyl ketoxime, and lactams such as ε-caprolactam and γ-caprolactam.

One of these curing agents containing a functional group capable of reacting with a hydroxyl group may be used alone, or two or more of them may be used in combination.

In the composition of the present invention, the content ratio of the silicone compound of the component (A), the hydroxyl group-containing resin of the component (B) and the curing agent of the component (C) is the same as that of the components (A), (B) and (C). (A) component is 5 to 50% by weight based on the total weight of
Component (B) is 10 to 80% by weight, and component (C) is 10 to 50% by weight.
Must be in the range of

When the content of the component (A) is less than 5% by weight, the effect of improving the acid resistance and weather resistance of the obtained coating film is not sufficiently exhibited, and when it exceeds 50% by weight, the mechanical properties of the obtained coating film, especially There is a tendency for flexibility to decrease. If the content of the component (B) is less than 10% by weight, the obtained coating film has poor mechanical properties, particularly flexibility, and if it exceeds 80% by weight, it is difficult to achieve high solid differentiation required for high solid paints. Becomes On the other hand, if the content of the component (C) is less than 10% by weight, the hardness of the obtained coating film is not sufficient, and if it exceeds 50% by weight, the mechanical properties, particularly flexibility, of the obtained coating film tend to decrease. Can be

The high solid coating composition of the present invention can be prepared by mixing the above components with a dispersing device used in the production of ordinary coating materials, for example, a ball mill, a sand mill, an attritor, or the like by an ordinary addition method. In this case, if necessary, pigments, dyes, glass flakes, colorants such as aluminum flakes, and other additives commonly used in paints, for example, pigment dispersants, viscosity modifiers, leveling agents, curing catalysts, gelling inhibitors , An ultraviolet absorber, a radical scavenger, and the like.

The paint obtained in this manner can be coated with a desired material to be coated, such as a metal or other inorganic material, plastic or other, by a usual coating method, for example, air spray coating, airless spray coating, electrostatic coating, dip coating, or the like. 1 coat, 1 coat, 2 coats 2 bake, 2 coats 1 bake, 3 coats 3 bake, 3 coats 2 bake, etc., and dried at a temperature of usually 60 to 180 ° C for about 20 to 60 minutes Thereby, an excellent coating film can be obtained.

[Examples] Next, the present invention will be described in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

 In addition, the coating film performance was evaluated as follows.

(1) Pencil hardness Using a pencil stipulated in JIS S-6006, the angle between the test piece and the pencil was 45 degrees, and the paint film was scratched. The hardness symbol is used as the evaluation value.

(2) 60 degree specular gloss JIS K-5400 6.7 Based on 60 degree specular gloss.

(3) QUU test An accelerated weather resistance test was performed using QUV [Q-Panel, trade name], and after lapse of 2000 hours, the 60-degree specular gloss and the time of occurrence of cracks in the coating film (cracks and cracks due to deterioration of the coating film) Was observed by visual observation).

(4) Acid resistance 0.2 ml of 0.4N HCl solution was put on the coating film, kept at 85 ° C for 15 minutes, and then visually inspected for spot marks immediately after rinsing with tap water, according to the following criteria. evaluated.

Good: There is no change in color and gloss in the coating film, and no defects such as blisters are observed.

Slightly poor: Some defects such as color, gloss change or blistering are observed in the coating film.

Poor: Defects such as color, gloss change or blistering are remarkably observed in the coating film.

(5) Flex resistance JIS K-5400 8.1 Flex resistance was evaluated according to the following criterion by a flex resistance test method.

Good: No cracking or peeling of the coating film was observed.

Poor: Cracks, peeling, etc. are observed in the coating film.

Production Examples 1 to 3 Production of Acrylic Resin Solution 61.8 parts by weight of methyl amyl ketone was charged into a four-necked flask equipped with a reflux condenser, a stirrer, a dropping funnel, and a thermometer, and heated to 150 ° C. while stirring. went. Next, a mixture 10 of the monomer component and the polymerization initiator shown in Table 1 was used.
0 parts by weight was added dropwise at a constant addition rate at 150 ° C. over 2 hours. After the completion of the dropwise addition, the reaction was terminated when the temperature was kept at 150 ° C. for further 2 hours to obtain acrylic resin solutions I to III having the characteristic values shown in Table 1, respectively.

Production Example 4 Production of Crosslinked Polymer Fine Particles (a) Production of Aqueous Dispersion of Crosslinked Polymer Fine Particles Surfactant aqueous solution deionized water 380.0 parts by weight Syntrex L100 ¹⁾ 7.0 parts by weight Polymerization initiator aqueous solution-1 deionized water 10.0 Parts by weight Sodium persulfate 0.3 parts by weight Vinyl-type monomer mixture 2-hydroxyethyl acrylate 2.0 parts by weight 1,6-hexanediol dimethacrylate 40.0 parts by weight Styrene 10.0 parts by weight n-butyl methacrylate 48.0 parts by weight Ionized water 10.0 parts by weight Sodium persulfate 0.3 parts by weight Note 1) Syntrex L100 [trade name of sodium lauryl sulfate, manufactured by NOF CORPORATION, active ingredient 100%] Stirrer, reflux condenser, dropping funnel (2 bottles) , A surfactant aqueous solution was charged into a flask equipped with a nitrogen inlet tube and a thermometer, and the temperature was raised to 80 ° C. under a nitrogen stream to raise the polymerization initiator aqueous solution-1
Was added. After the temperature was raised to 80 ° C. again, the vinyl-type monomer mixture was added dropwise over 3 hours while maintaining the mixture in the flask at 80 ± 2 ° C. During the dropping of the monomer mixture, the polymerization initiator aqueous solution-2 was dropped over 2 hours from 1 hour after the start of dropping. Vinyl type monomer mixture and polymerization initiator aqueous solution-2
After completion of the dropwise addition, the mixture was further polymerized at 80 ° C. for 2 hours to obtain an aqueous dispersion A1 of crosslinked polymer fine particles having the characteristic values shown in Table 2.

(B) Production of non-aqueous dispersion of crosslinked polymer fine particles Aqueous dispersion A1 of crosslinked polymer fine particles obtained in (a),
To 500 parts by weight, add 200 parts by weight of methyl isobutyl ketone and 22.7 parts by weight of a 3N aqueous solution of NaOH and raise the temperature to 85 ° C to 85 ± 2.
The hydrolysis reaction was performed at a temperature of 3 ° C. for 3 hours. Then, the temperature was lowered to 80 ° C., neutralized by adding 22.7 parts by weight of a 3N aqueous hydrochloric acid solution, and then 18.5 parts by weight of the acrylic resin solution III obtained in Production Example 3 as a particle dispersion-stabilizing resin was added, followed by stirring for 10 minutes. Thereafter, 25 parts by weight of a 20% by weight aqueous solution of triethylamine acetate (described later) was added, and stirring was immediately stopped.
The organic layer in which the crosslinked polymer particles were dispersed was separated into the upper layer, and the aqueous layer was separated below, so the lower aqueous layer was removed.

200 parts by weight of deionized water was added to the organic layer in which the remaining crosslinked polymer fine particles were dispersed, and the temperature was raised to 70 ° C. with stirring, and when the temperature reached 70 ° C., a 20% by weight aqueous solution of triethylamine acetate was added.
12.5 parts by weight was added, stirring was immediately stopped, and the mixture was allowed to stand. again,
Since the organic layer in which the crosslinked polymer particles were dispersed was separated into an upper layer and the aqueous layer was separated into a lower layer, the lower aqueous layer was removed. 1.7% by weight of water remained in the remaining organic layer by a Karl Fischer moisture meter.

Next, the temperature of the organic layer was cooled to 50 ° C., and 70 parts by weight of methyl orthoformate was added dropwise from the dropping funnel over 30 minutes, and the reaction was continued at 50 ° C. for 30 minutes to decompose residual water. Thereafter, 200 parts by weight of xylene was added, a new Dean-Stark trap was attached between the reflux condenser and the flask, the upper part of the reflux condenser was connected to the aspirator, and the inside of the flask was evacuated under heating and stirring, and 300 ± 100 mmHg, 80 The solvent was distilled off under a condition of ± 10 ° C. until the nonvolatile content of the dispersion became 40% by weight to obtain a non-aqueous dispersion A2 of crosslinked polymer fine particles. Table 2 shows the characteristic values of the obtained non-aqueous dispersion.

(Preparation method of 20% by weight aqueous solution of triethylamine acetate salt) 7.5 parts by weight of acetic acid is dissolved in 80 parts by weight of deionized water, and 12.5 parts by weight of triethylamine is added thereto while stirring at room temperature.
Prepared by addition over 30 minutes.

Example 1 (1) Preparation of paint for base coat ・ 111.2 parts by weight of acrylic resin solution III obtained in Production Example 3 ・ Methylated melamine resin [98% by weight heating residue, Cymel
303, manufactured by American Cyanamid Co., Ltd .; 30.6 parts by weight ・ Non-aqueous dispersion of crosslinked polymer fine particles obtained in Production Example 4
A2 83.5 parts by weight ・ Aluminum pigment [65% by weight of heating residue, aluminum paste 7160N, manufactured by Toyo Aluminum Co., Ltd., trade name] 15.4 parts by weight ・ Sulfonic acid catalyst (described later) 1.6 parts by weight ・ UV absorber [Tinuvin 900 10.0 parts by weight of a 10% by weight xylene solution of Ciba Geigy Co., Ltd.] 1.0 part by weight of n-butyl alcohol A paint having the above composition was coated with a thinner (toluene / xylene / n
-Butyl alcohol = 5/3/2 weight ratio) to dilute the coating viscosity (Ford Cup No. 4, 14 seconds at 20 ° C.) to prepare a coating for base coat.

Necked flask fitted with a stirrer (preparation of sulfonic acid _{catalyst), C 18 H 37 SO 3} Na3
A mixture of 56.0 parts by weight and 861.4 parts by weight of n-butyl alcohol was added, and 98.1 parts by weight of 37.2% by weight hydrochloric acid was added with stirring at room temperature to remove sodium. At this time, the sodium removal reaction proceeds immediately after the addition of hydrochloric acid, and 58.5 parts by weight of
NaCl precipitated. After filtering out the precipitated NaCl by absorption filtration, 79.0 parts by weight of pyridine was added to the filtrate, and an aliphatic sulfonic acid compound solution having an active ingredient concentration (aliphatic sulfonic acid) of 25% by weight blocked with an equimolar amount of pyridine was added. Obtained.

(2) Preparation of paint for clear coat ・ Silicone compound [heating residue 70% by weight, molecular weight 3,00
0, effective hydroxyl equivalent 343, KR-214, manufactured by Shin-Etsu Chemical Co., Ltd., trade name] 10.0 parts by weight ・ Acrylic resin solution II obtained in Production Example 2 133.3 parts by weight ・ Methylated melamine resin [Heating residue 98% by weight, Cymel
303, manufactured by American Cyanamid Co., Ltd., 13.3 parts by weight-Tinuvin 900 in 10% by weight xylene solution
(1)] 10.0 parts by weight ・ 10 parts by weight of a 10% by weight xylene solution of a hindered amine light stabilizer [Sanol LS440, manufactured by Ciba Geigy Co., Ltd.] 10.0 parts by weight ・ Sulfonic acid catalyst [supra, (1)] 1.6 parts by weight ・ n -Butyl alcohol 1.0 part by weight A paint having the above composition was applied to a thinner (toluene / xylene / n
-Butyl alcohol = 4/4/2 weight ratio) was diluted to a coating viscosity (Ford Cup No. 4, at 20 ° C. for 25 seconds) to prepare a clear coat paint.

(3) Preparation of coating film A cationic electrodeposition paint [Aqua No.4200, trade name, manufactured by NOF CORPORATION] is applied to a zinc phosphate-treated mild steel sheet with a dry film thickness of 20 µm
Electrodeposition coating, baking at 175 ° C for 25 minutes, and air spray coating with a middle coating (trade name: Epico No. 1500CP Sealer, manufactured by Nippon Oil & Fats Co., Ltd.) to a dry film thickness of 40 μm. A test plate baked at 30 ° C. for 30 minutes was prepared. On this test plate, the base coat paint of the above (1) was dried at an interval of 1 minute 30 seconds and a dry film thickness of 20 μm in two stages.
It was air spray painted so that After setting horizontally for 3 minutes, the paint for clear coating of the above (2) was applied by air spray and baked horizontally at a temperature of 140 ° C. for 30 minutes to obtain a smooth coating film. As shown in Table 5, this coating film was excellent in acid resistance and weather resistance.

Examples 2-3 (1) Preparation of paint for base coat A mixture of the raw material compositions shown in Table 3 was used in Example 1 (1).
By performing the same operation as described above, each base coat paint was prepared.

(2) Preparation of clear coat A mixture having the raw material composition shown in Table 4 was used in Example 1 (2).
By performing the same operation as described above, each clear coat paint was prepared.

(3) Preparation of coating film Example 1 was prepared using each of the obtained paints (1) and (2).
By performing the same operation as in (3), Examples 2 and 3
In each case, a coating film having smoothness and excellent acid resistance and weather resistance as shown in Table 5 was obtained.

Example 4 (1) Preparation of paint for base coat ・ 88.0 parts by weight of acrylic resin solution III obtained in Production Example 3 ・ Non-aqueous dispersion of crosslinked polymer fine particles obtained in Production Example 4
A2 55.7 parts by weight-Aluminum paste 7160N [supra, Example 1] 15.4 parts by weight-10% by weight xinylene solution of tinuvin 900 [supra, example 1] 10.0 parts by weight Hexamethylene was added to the mixture of the above composition immediately before coating. 45.0 parts by weight of a diisocyanate trimer [heating residue 100%, isocyanate group content 21% by weight, coronate EH, manufactured by Nippon Polyurethane Industry Co., Ltd.] was added, and a thinner (toluene / xylene / acetic acid n- A base coat paint was prepared by diluting the coating viscosity (Ford Cup No. 4, 14 seconds at 20 ° C.) with a butyl = 4/4/2 weight ratio.

(2) Preparation of paint for clear coat ・ Silicone compound [heating residue 70% by weight, molecular weight 3,00
0, effective hydroxyl equivalent 420, KR-211, manufactured by Shin-Etsu Chemical Co., Ltd., trade name] 14.3 parts by weight ・ 75.0 parts by weight of acrylic resin solution III obtained in Production Example 3 ・ 10% by weight xylene of tinuvin 900 Solution [supra, Example 1] 10.0 parts by weight-10% by weight xanol solution of SANOL LS440 [supra, Example 1] 10.0 parts by weight Coronate EH [supra, (1)] 45.0 parts by weight and diluting with a thinner (xylene / n-butyl acetate = 5/5 weight ratio) to a coating viscosity (Ford Cup No. 4, 25 seconds at 20 ° C.) to give a clear coat paint. Produced.

(3) Preparation of coating film Example 1 using each of the obtained paints (1) and (2).
By performing the same operation as in (3), a smooth coating film having excellent acid resistance and weather resistance as shown in Table 5 was obtained.

Comparative Examples 1 to 3 (1) Preparation of Base Coating Paint A mixture having exactly the same raw material composition as the base coating paints of Examples 1 to 3 was subjected to the same operation as in Example 1 (1) to obtain Comparative Examples. 1 to 3 base coat paints were prepared.

(2) Preparation of Clear Coating Paint A mixture having the raw material composition shown in Table 6 was used in Example 1 (2).
By performing the same operation as described above, each clear coat paint was prepared.

(3) Preparation of coating film Example 1 was prepared using each of the obtained paints (1) and (2).
The same operation as in (3) was performed, but as shown in Table 7, a coating film satisfying both the coating film performance and the weather resistance was not obtained. That is, in Comparative Example 1, the coating film was insufficient in acid resistance and bending resistance and slightly inferior in weather resistance. This is because the amount of the silicone compound in the clear coat was less than 5% by weight, the effect of improving the acid resistance and weather resistance was not sufficient, and the amount of the curing agent in the clear coat exceeded 50% by weight, so that the bending resistance was low. Was inferior to In Comparative Example 2, although the effect of improving acid resistance and weather resistance was observed, a coating film having insufficient flex resistance was obtained. This is because the amount of the silicone compound in the clear coat exceeded 50% by weight, and the amount of the hydroxyl group-containing resin was less than 10% by weight. In Comparative Example 3, the coating film was insufficient in acid resistance and coating film hardness. This was inferior in acid resistance because the amount of the silicone compound in the clear coat was less than 5% by weight, and further inferior in film hardness because the amount of the curing agent in the clear coat was less than 10% by weight.

[Effects of the Invention] According to the present invention, two or more hydroxyl groups chemically bonded to a silicon atom are contained per molecule and the weight average molecular weight is 20
By containing a silicone compound having a hydroxyl equivalent of 100 to 600 in a range of 0 to 4,000, a high solid coating composition capable of forming a coating film having excellent acid resistance and weather resistance can be obtained.

Claims (1)

(57) [Claims] (A) a weight average molecular weight of from 200 to 4,000 having (A) two or more hydroxyl groups chemically bonded to a silicon atom per molecule;
And 5 to 50% by weight of a silicone compound having a hydroxyl equivalent of 100 to 600, (B) 10 to 80% by weight of a hydroxyl group-containing resin, and (C) 10 to 50% by weight of a curing agent having a functional group capable of reacting with a hydroxyl group. A high solid coating composition containing a resin mixture as a main component.