JP2003049118A - Coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition which can form coating films having excellent adhesiveness to steel materials, excellent corrosion resistance, excellent weather resistance, and the like. SOLUTION: This coating composition is characterized by comprising (A) a mercapto group-having organopolysiloxane prepared by hydrolyzing and condensing (a) an organic silicon compound having a mercapto group capable of reacting with an epoxy group and a hydrolysable group directly bonded to a silicon atom and (b) an organosilane represented by general formula (1): R<1> n Si(OR<2> )4-n [R<1> is a 1 to 8C organic group; R<2> is a 1 to 5C alkyl; (n) is 1 or 2] and/or its partially hydrolyzed condensation product, and (B) an epoxy resin having two or more epoxy groups in the molecule.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is capable of room temperature curing,
The present invention relates to a coating composition which forms a coating film having excellent adhesion, corrosion resistance, weather resistance and the like.

[0002]

2. Description of the Related Art In recent years, inorganic polysiloxane inorganic coatings containing organosilane and / or its partial hydrolyzed condensate as a binder form a coating film having excellent weather resistance and stain resistance. Widely used in various fields. However, the inorganic coating has been used only as a finishing coating because it has problems of poor adhesion to steel and corrosion resistance when it is applied to large steel structures such as bridges and tanks. That is, conventionally, the coating system for steel materials using an organopolysiloxane-based inorganic coating is usually an epoxy resin coating having excellent adhesion to steel and corrosion resistance as a primer, and then a primer coating and an organopolysiloxane-based coating. An intermediate paint having excellent adhesion was applied to both of the inorganic coating films, and then an organopolysiloxane inorganic paint was applied as a finishing paint. Therefore, there are many coating processes and there is a problem in coating workability.

[0003]

The present invention has been made against the background of the problems of the prior art as described above, and has improved the workability of coating on steel materials, that is, the coating of a primer or an intermediate coating paint is omitted. It is an object of the present invention to provide a room temperature curable coating composition capable of forming a coating film having excellent adhesion, corrosion resistance, weather resistance and the like.

[0004]

Means for Solving the Problems The inventors of the present invention have made extensive studies in order to achieve the above-mentioned objects, and as a result, have found that the above-mentioned objects can be achieved by the following constitutions, and have arrived at the present invention. That is, the present invention relates to the following inventions. (A) an organosilicon compound (a) having a mercapto group capable of reacting with an epoxy group and a hydrolyzable group directly bonded to a silicon atom, and a compound represented by the general formula (1), R ¹ _n Si (OR ² ) _{4 -n} [In the formula, R ¹ is an organic group having 1 to 8 carbon atoms, and R ² is
It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. ] An organopolysiloxane having a mercapto group formed by subjecting an organosilane and / or a partial hydrolysis-condensation product (b) thereof represented by the above to a hydrolysis-condensation reaction, and (B) two or more epoxy groups in one molecule. The present invention relates to a coating composition comprising an epoxy resin having

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. Each constituent component of the coating composition of the present invention will be described. [About component (A)] About component (a) The component (a) is an organosilicon compound having a mercapto group capable of reacting with an epoxy group and a hydrolyzable group directly bonded to a silicon atom. As the component (a), for example, a compound having the following structural formula can be used. Formula ^{(2), (HSR 4)} n (R 5) m Si (OR 3) 4-nm ( wherein, R ³ is an alkyl group of 1 to 5 carbon atoms, R ⁴
Is an alkylene group having 1 to 5 carbon atoms, R ⁵ is an alkyl group having 1 to 5 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or an aryl group having 6 to 8 carbon atoms, and n is 1 or 2, and m is 0 or 1. ) The alkyl group as R ³ may be linear or branched. Examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, and an n-group.
Preferable examples are alkyl groups such as -butyl group, i-butyl group, s-butyl group, t-butyl group, and pentyl group. A preferred alkyl group has, for example, 1 to 2 carbon atoms.

The alkylene group as R ⁴ may be linear or branched. Examples of such an alkylene group include a methylene group, an ethylene group, a propylene group and the like. The alkyl group having 1 to 5 carbon atoms as R ^{5 is the same} as the above R ³ . Moreover, examples of the cycloalkyl group as R ⁵ include a cyclohexyl group, a cycloheptyl group, and the like. Moreover, examples of the aryl group as R ⁵ include a phenyl group and a naphthyl group. Examples of the organosilicon compound (a) represented by the general formula (2) include γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, and γ-mercaptopropyltrimethoxysilane. Typical examples include mercaptopropylmethyldiethoxysilane.

Component (b) The component (b) is represented by the general formula (1), R ¹ _n Si (OR ² ) _4-n [wherein R ¹ is an organic group having 1 to 8 carbon atoms, R ² is
It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. ] The organosilane or its liquid partial hydrolysis-condensation product shown by these. Examples of the organic group as R ¹ include an alkyl group, a cycloalkyl group, an aryl group,
Examples thereof include a vinyl group. Here, the alkyl group may be linear or branched. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group,
Examples thereof include alkyl groups such as i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, heptyl group and octyl group. Preferred alkyl groups have 1 to 4 carbon atoms.

Preferable examples of the cycloalkyl group include a cyclohexyl group, a cycloheptyl group, a cyclooctyl group and the like. As the aryl group, for example,
Examples thereof include a phenyl group and a naphthyl group. Each of the above functional groups may optionally have a substituent. Examples of such a substituent include a halogen atom (for example, a chlorine atom,
Bromine atom, fluorine atom, etc.), (meth) acryloyl group, alicyclic group and the like. In addition, since the phenyl group has excellent compatibility with the epoxy resin (B) described later, the organosilane or its partial hydrolyzed condensate in which R ¹ is a phenyl group in all components (b) is, for example, 10 mass%. % Or more, preferably 20 to 90% by mass is preferably used.

The alkyl group as R ² may be linear or branched. Examples of such an alkyl group include a methyl group, an ethyl group, an n-propyl group,
Examples thereof include an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, and a pentyl group, and a preferable alkyl group has a carbon number of 1 to 2.
Specific examples of the organosilane represented by the general formula (1) include, for example, methyltrimethoxysilane and
Methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, γ-chloropropyltrimethoxysilane ,

Γ-chloropropyltriethoxysilane,
Vinyltrimethoxysilane, vinyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, cyclohexyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, methylphenyldimethoxysilane , Dimethyldipropoxysilane, etc., but preferably methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysila And dimethyldimethoxysilane.

These organosilanes may be used alone or in combination of two or more.
The component (b) may be a partially hydrolyzed condensate of these organosilanes. The polystyrene equivalent weight average molecular weight of the condensate is, for example, 300 to 5,000, preferably 500 to 4,200. By using such a condensate, a coating film having good storage stability and good adhesion can be obtained.

Specific examples of such a condensate include commercially available products such as SR2 manufactured by Toray Dow Corning.
402, DC3037, DC3074; Shin-Etsu Chemical Co., Ltd. KR-211, KR-212, KR-213,
KR-214, KR-216, KR-218; TSR-145, TSR-160, TS manufactured by Toshiba Silicone Co., Ltd.
R-165, YR-3187 etc. are mentioned.

Next, a method for producing the organopolysiloxane (A) having a mercapto group, which is the resin component for coating material of the present invention, will be described. Organopolysiloxane (A)
Is produced by subjecting the mixture of the above-mentioned component (a) and component (b) to hydrolysis and condensation reaction in the presence of water and a catalyst. The mixing ratio of the component (a) and the component (b) is such that the organopolysiloxane (A) having a mercapto group is used.
Has an active hydrogen equivalent (solid content) of, for example, 150 to 100.
A ratio of 0, preferably 300 to 800 is suitable.

The amount of water is, for example, 45 to 100%, preferably 50 to 90% of the hydrolyzable group initially present in the mixture of the components (a) and (b). Is a sufficient amount for the hydrolysis and condensation reaction, and specifically, for example, 0.45 to 0.45 of the total number of hydrolyzable groups in the mixture.
A suitable amount is 1.0 times, preferably 0.5 to 0.9 times the number of moles. The hydrolysis-condensation reaction is carried out by adding a mixture of the above components to water, optionally in the presence of a catalyst, for example,
40-80 ° C, preferably 45-65 ° C, generally,
A method of reacting while stirring for 2 to 10 hours is suitable, but not limited to this method.

The reaction catalyst optionally used is, for example, trialkoxyborane such as trimethoxyborane or triethoxyborane; tri-n-butoxyethylacetoacetate zirconium, di-n-butoxydi (ethylacetoacetate) zirconium, Zirconium chelate compounds such as tetrakis (ethylacetoacetate) zirconium, titanium isochelate compounds such as diisopropoxybis (acetylacetate) titanium, diisopropoxybis (ethylacetoacetate) titanium, monoacetylacetate bis (ethylacetoacetate) aluminum, Examples thereof include organic metal compounds such as aluminum chelate compounds such as diisopropoxyethyl acetoacetate aluminum and inorganic acids such as hydrochloric acid.

The hydrolysis-condensation reaction product is a solution of an organosiloxane (A) having a mercapto group in a solution state, depending on the alcohol content produced in the reaction, or the alcohol content and an organic solvent which will be described later added if necessary. ) A solution can be synthesized.

[About component (B)] The epoxy resin (B) used in the present invention is an epoxy resin having two or more epoxy groups in one molecule, and particularly, the epoxy equivalent is, for example, 150 to 1500, preferably 180-
The range of 1000 is preferable from the viewpoints of corrosion resistance and weather resistance of the obtained coating film. As such an epoxy resin (B), a bisphenol A type epoxy resin which is usually used for paints, a bisphenol F type epoxy resin, a phenol novolac type epoxy resin, an alkyl ether type epoxy resin, a hydrogenated bisphenol A type epoxy resin. Resins and the like are preferable, and these resins may be used alone or in combination of two or more.

The mixing ratio of the component (A) and the component (B) is
The ratio of the active hydrogen equivalent of the former and the epoxy equivalent of the latter is
For example, 0.7 to 1.3, preferably 0.9 to 1.1.
Is appropriate. When the components (A) and (B) are coated, the mercapto group in the component (A) reacts with the epoxy group in the component (B) to cure the coating film.

[Component (C)] In the present invention, optionally, inorganic particles having photocatalytic activity (component (C)).
Can be used. The inorganic particles may be in the form of a sol. This ingredient is antibacterial and
In order to impart antifungal properties, antifouling properties, and the action of decomposing and removing nitrogen oxides in the air, they are blended as necessary. As such a component, for example, TiO 2
₂ , TiO ₃ , SrTiO ₃ , FeTiO ₃ , WO ₃ , Sn
O ₂ , BiO ₂ , In ₂ O ₃ , ZnO, Fe ₂ O ₃ , Ru
O ₂ , CdO, CdS, CdSe, GaP, GaAs,
CdFeO ₃ , MoS ₂ , LaRhO _{3 and the} like,
Preferred is TiO ₂ .

The content of the component (C) is 0 to 60% by mass, preferably 10 to 50% by mass in the solid content of the coating composition.
Is appropriate. The coating composition of the present invention comprises the above-described component (A), component (B) and component (C) optionally blended, and further, if necessary, the solid content of the coating, It contains a solvent for adjusting to about 20 to 70% by mass, a filler, a dye, and various additives such as a curing accelerator, an ultraviolet absorber, a light stabilizer, a thickener, and a pigment dispersant. be able to.

Examples of such a solvent include alcohols such as methanol, ethanol, propyl alcohol and butanol, alcohol ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether and propylene glycol monopropyl ether, acetone, In addition to hydrophilic solvents such as ketones such as methyl ethyl ketone, various coating solvents such as toluene, xylene, ethyl acetate, and butyl acetate can be used.

Examples of the filler include talc, body pigments for various paints such as talc, barium carbonate, calcium carbonate, barium carbonate, bentonite, titanium oxide, carbon black, red iron oxide, lithopone and the like, and further rust prevention. Pigments can be used. The content of the filler is 0 to 70% by mass, preferably 0 to 50% by mass in the solid content of the coating composition.

The coating composition of the present invention can be applied to the surface of an object to be coated with a coating means such as a brush, spray, roll, dipping, etc. to form a cured coating film at room temperature, but forced drying or It may be cured by heating. Examples of the object to be coated include metals such as steel plates, but it is also possible to use various objects to be coated such as an inorganic ceramic substrate, a glass substrate, a plastic substrate, and a paper substrate.

[0024]

EXAMPLES The present invention will now be described in more detail with reference to examples. In the examples, “parts” and “%” are based on mass unless otherwise specified.

Synthesis Example 1 A reactor equipped with a reflux condenser and a stirrer was charged with 15 parts of propylene glycol mono-n-propyl ether and 10 parts of xylene, and γ-mercaptopropyltrimethoxysilane was added at room temperature and with stirring. 50 parts of 2 parts of a partial hydrolysis cocondensation product of phenyltrimethoxysilane (DC3074 manufactured by Toray Dow Corning Co., Ltd .; solid content 100%)
After 0 parts and 30 parts of methyltrimethoxysilane were added and mixed, 9.0 parts of ion-exchanged water and 5 parts of isopropyl alcohol were added and reacted at 60 ° C. for 3 hours. Next, 0.5 part of triethoxyborane was added, and stirring was continued at 60 ° C. for 3 hours to give a solid content of 60% and an active hydrogen equivalent of 510.
(Varnish value) organopolysiloxane solution (A-1)
Got

Synthesis Example 2 A reactor equipped with a reflux condenser and a stirrer was charged with 20 parts of propylene glycol mono-n-propyl ether and 10 parts of xylene, and γ-mercaptopropyltrimethoxysilane was added at room temperature and with stirring. 40 parts of phenyltrimethoxysilane partially hydrolyzed co-condensate (DC3074 manufactured by Toray Dow Corning Co., Ltd .; solid content 100%) 2
0 part, partially hydrolyzed cocondensate of phenyltrimethoxysilane (DC3037 manufactured by Dow Corning Toray Co., Ltd .;
30 parts of solid content 100%) and 10 parts of methyltrimethoxysilane were added and mixed, and then 7.2 parts of ion-exchanged water and 5 parts of isopropyl alcohol were added, and the mixture was mixed at 60 ° C. for 3 days.
Reacted for hours. Next, 0.5 part of triethoxyborane was added, and stirring was continued at 60 ° C. for 3 hours to give a solid content of
%, And an active hydrogen equivalent of 680 (varnish value) was obtained as a polyorganosiloxane solution (A-2).

Synthesis Example 3 In a reactor equipped with a reflux condenser and a stirrer, 50 parts of isopropyl alcohol and a partially hydrolyzed cocondensate of phenyltrimethoxysilane (DC3037 manufactured by Toray Dow Corning Co .; solid content 100) %) And 3 parts of a partially hydrolyzed condensate of methyltrimethoxysilane (SR2402 manufactured by Toray Dow Corning Co., Ltd .; solid content 100%).
After 0 parts and 30 parts of methyltrimethoxysilane were added and mixed, 6.0 parts of ion-exchanged water and 0.05 parts of 0.1N hydrochloric acid aqueous solution were added and reacted at 60 ° C. for 3 hours. Next, 1.5 parts of ion-exchanged water was added, and stirring was continued at 60 ° C. for 3 hours to obtain an organopolysiloxane solution (A-3) having a solid content of 55%.

Examples 1 to 4 and Comparative Examples 1 to 2 Component 2 [component (B)], component 4 and component 5 shown in Table 1 were
After mixing in the proportions shown in Table 1, the component (1) [component (A)] and the component (3) were added, and stirring was continued until uniform mixing was performed to prepare a coating material.

[0029]

[Table 1] Table 1 Note 1) Epoxy resin Epicoat 1004 (epoxy equivalent: 900) (bisphenol A type epoxy resin, 2 epoxy groups) manufactured by Yuka Shell Epoxy Co., Ltd. was diluted with xylene to a solid content of 50%. Note 2) Epoxy resin Epicoat 1001 (epoxy equivalent: 450) (bisphenol A type epoxy resin, 2 epoxy groups) manufactured by Yuka Shell Epoxy Co., Ltd. was diluted with xylene to a solid content of 70%. Note 3) Sanwa Chemical Industry Co., Ltd., modified polyamine (solid content: 50%, active hydrogen equivalent: 290 (solid content)) is used as a curing agent. Note 4) Dibutyltin dilaurate is used as a curing accelerator. Note 5) Photocatalytic titanium oxide manufactured by Ishihara Sangyo Co., Ltd. (average particle size 8 μm)

With respect to the obtained coating compositions of Examples 1 to 4 and Comparative Examples 1 and 2, test plates were prepared as follows, and the coating film appearance, corrosion resistance, stain resistance, and weather resistance were applied. A membrane performance test was conducted and the results are shown in Table 2. <Coating film performance test> A coating composition shown in Table 1 was spray-coated on a steel sheet degreased with xylene so that the dry film thickness was about 80 μm, and the coating composition was dried at 20 ° C. for 10 days, and then a test plate. Used as. The test method and evaluation criteria were as follows. Appearance : The appearance of the coating film formed on the coated plate was visually evaluated. Evaluation Criteria ○: A glossy, smooth film. Δ: Although glossy, the smoothness of the film is poor. X: There is no gloss and the smoothness of the film is poor.

Anticorrosion property : A salt spray test was carried out for 150 hours according to JIS K5400.9.1, and then the state of the coating film was visually judged. Evaluation criteria ○: No change Δ: Minor changes such as decrease in gloss and whitening ×: Large changes such as decrease in gloss and whitening

Contamination resistance : After 24 hours from application of the red and black magic inks, wipe with a cloth moistened with xylene, and the decontamination property was visually judged. Evaluation criteria ◎: Complete removal ○: Very slight contamination △: Slight contamination ×: Significant contamination

Weather resistance : Sunshine weather-O-meter 1000 hour evaluation standard ○: No change in appearance of coating film, gloss retention rate of 95% or more △: slight change in appearance of coating film, gloss retention rate of 80 to 94
% ×: The change in coating film is remarkable, the gloss retention rate is less than 80%

[0034]

[Table 2] Table 2

As is clear from Table 2, Examples 1 to 4, which are coating compositions of the present invention, had excellent coating film performance. On the other hand, in Comparative Example 1 containing no organopolysiloxane, the weather resistance was poor, and in Comparative Example 2 containing the organopolysiloxane having no mercapto group, the corrosion resistance was poor.

[0036]

EFFECTS OF THE INVENTION The coating composition of the present invention can form a coating film having excellent adhesion to steel, corrosion resistance, weather resistance and the like.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Toru Taki, the inventor             7-1414 Shimonagata, Nishinasuno Town, Nasu District, Tochigi Prefecture             34 (72) Inventor Masanori Nagai             1926-9 thin leaf, Otawara City, Tochigi Prefecture F-term (reference) 4J038 DB041 DB042 DB061 DB062                       DB071 DB072 DL031 DL032                       DL071 DL072 DL091 DL092                       HA216 KA06 KA08 MA14                       NA03 NA04 NA12 PA18 PA19                       PC02 PC03 PC04 PC08 PC10

Claims (4)

[Claims] 1. An organosilicon compound (a) having (A) a mercapto group capable of reacting with an epoxy group, and a hydrolyzable group directly bonded to a silicon atom, and a compound of the general formula (1), R ¹ _n Si (OR ² ) _4-n [In the formula, R ¹ is an organic group having 1 to 8 carbon atoms, and R ² is
It is an alkyl group having 1 to 5 carbon atoms, and n is 1 or 2. ] An organopolysiloxane having a mercapto group formed by subjecting an organosilane and / or a partial hydrolysis-condensation product (b) thereof represented by the above to a hydrolysis-condensation reaction, and (B) two or more epoxy groups in one molecule. A coating composition containing an epoxy resin having: 2. The epoxy resin (B) is 100 to 1
At least selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, alkyl ether type epoxy resin and hydrogenated bisphenol A type epoxy resin having an epoxy equivalent in the range of 500. The coating composition according to claim 1, which is one type of epoxy resin. 3. The coating composition according to claim 1, wherein R ¹ in the general formula (1) is a phenyl group. 4. The coating composition according to claim 1, further comprising inorganic fine particles (C) having photocatalytic activity.