JPH03115378A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which gives a coating film excellent in anticorrosiveness and adhesiveness and is suitable especially for recoating or mending a fluororesin coating film by mixing a solvent-insoluble epoxidized fluorocopolymer, an epoxy resin, and a curing agent. CONSTITUTION:An objective composition contains 100 pts.wt. solvent-insoluble fluorocopolymer having an epoxy group as the site undergoing curing reaction in the molecule, 1-100 pts.wt., preferably 20-80 pts.wt., epoxy resin, and a curing agent.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a coating composition that provides a coating film with excellent corrosion resistance, adhesion, etc., and is particularly suitable for repainting and repairing fluororesin coatings. relating to things.

[Conventional technology and problems to be solved] Fluororesin-based paints have traditionally been known as paints with good weather resistance, but in recent years, solvent-soluble fluorine-containing copolymers have been developed, and they are used as binders. Fluororesin paints can be used on steel structures such as tanks, chimneys, bridges, and architecture! It has come to be widely applied to various objects such as iron and other objects. For the purpose of saving labor, it has become common for these objects to be painted to be painted at a factory and then erected on site. In such cases, during transportation or installation of the pre-painted object (or parts thereof), the paint film suffers damage such as scratches, peeling, breakage, etc., and this damage often extends to the base material. In addition, there are some areas where rust occurs during repainting, so it is necessary to apply anti-corrosion paint before applying the top coat. Therefore, in order to protect the substrate from rust, it is necessary to apply an epoxy resin paint that is usually erodible. Therefore, it was necessary to sufficiently polish and roughen the surface of the fluororesin coating using disc sandpaper, sandpaper, etc., or to remove the fluororesin coating before applying epoxy resin paint. . As a result, the painting process and man-hours are significantly increased and the painting process becomes complicated.

In view of the current situation, the inventors of the present invention have developed a system for not only unpainted objects, but also for repairing and repainting fluororesin coatings.
A coating composition that has excellent adhesion without surface treatments such as polishing or roughening, has excellent adhesion to materials such as iron, has excellent corrosion resistance, and can be coated with various top coats. developed something.

[Means to solve the problem]

That is, the present invention includes the following components: (a) a solvent-soluble fluorine-containing copolymer having an epoxy group as a curing reactive site in the molecule, (b) an epoxy resin, and (c) a curing agent, and (b) for 100 parts by weight of component (a).
The present invention relates to a coating composition comprising 1 to 100 parts by weight of the components.

The present invention will be explained in detail below.

The fluorine-containing copolymer used as component (a) in the present invention is a fluorine-containing copolymer having an epoxy group as a curing reactive site in the nine molecules and is soluble in a solvent at room temperature. As such a fluorine-containing copolymer, a copolymer consisting of a fluoroolefin and a comonomer capable of copolymerizing with the fluoroolefin is preferably employed. As a fluoroolefin,
Tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene and the like are preferably employed. As the comonomer, an ethylenically unsaturated compound copolymerizable with a fluoroolefin or the like is employed. Examples of such ethylenically unsaturated compounds include olefins, vinyl ethers, vinyl esters, allyl ethers, and compounds containing acryloyl or methacryloyl groups. In particular, vinyl ethers, vinyl esters, and allyl ethers are preferably employed because they have excellent copolymerizability with fluoroolefins.

In order to provide component (a) with an epoxy group, glycidyl vinyl ether is used as a part of the comonomer, and approximately
Copolymerize at a ratio of 15 mol%. Alternatively, as described in JP-A-1-113451, a hydroxyl group-containing fluorine-containing copolymer is reacted with an incyanate group-containing unsaturated monomer having an incyanate group and an addition-polymerizable unsaturated group. It is also possible to impart epoxy groups to the unsaturated group-containing fluorine-containing copolymer obtained by reacting with glycidyl acrylate or glycidyl methacrylate. The ratio of the epoxy group-containing monomer is preferably within the above range; if it exceeds the above range, the flexibility of the resulting coating film will decrease, and the workability of the coating will tend to deteriorate; If it is too small, the solvent resistance of the resulting coating film will decrease,
Furthermore, the curing time tends to be longer. The number average molecular weight of component (a) thus obtained was approximately 5,000 to 30,
000 is appropriate.

The epoxy resin used in the present invention as component ('b) is a resin having an epoxy equivalent of about 150 to 1.200,
Ordinary solvent-soluble paint epoxy resins can be used. Specifically, for example, Epicoat 828 and Epicoat 834, which are generally commercially available as bisphenol-type epoxy resins, are used.
, 836, 1001, 1004, DX-255
(Product name manufactured by Yuka Shell Epoxy Co., Ltd.), Araldite GY-260 (Product name manufactured by Ciba Geigy Co., Ltd.), DER3
30, 331, 337 (trade names manufactured by Dow Chemical Co., Ltd.), Evicron 800 (trade names manufactured by Dainippon Ink and Chemicals Co., Ltd.); (Product name manufactured by Chemical Co., Ltd.); ARALDAI) CT- which is generally commercially available as a polyglycol type epoxy resin
508 (product name manufactured by Ciba Geigy), DER-732
, Same 736 (all product names manufactured by Dow Chemical Company); Evicron 200 and Same 400 as ester type epoxy resins
(The above are trade names manufactured by Dainippon Ink and Chemicals Co., Ltd.); BF-10, which is generally commercially available as a linear aliphatic epoxy resin
00 (trade name manufactured by Nippon Soda Co., Ltd.) and the like are representative examples. Other polyol type epoxy resins, alicyclic epoxy resins, halogen-containing epoxy resins, etc. can also be used.

The amount of the epoxy resin (b) component is (a) component 1
1 to 100 parts by weight, preferably 20 to 00 parts by weight
80 parts by weight is suitable. If the amount of component (b) exceeds the above range, the adhesion to the fluororesin coating will decrease, and if it is too low, the anticorrosion effect of the epoxy resin will decrease, which is not preferred.

The curing agent that is component (c) used in the present invention is not particularly limited as long as it reacts with the epoxy groups of components (a) and (b) at room temperature and forms a cured coating film, but representative For this purpose, those commonly used for paints such as amine adducts and polyamide resins can be used. Specifically, for example, Tomide ¥-25, Tomide ¥245, Tomide ¥2400, Tomide ¥2500, which are generally commercially available as polyamide resins.
(The above are product names manufactured by Fuji Kasei Kogyo Co., Ltd.), Xenamide 200
0, Persamide 115, Persamide 125 (all product names manufactured by Daiichi General), Persamide 320, Persamide 330, Persamide X20
00 (trade names manufactured by Sanso Kagaku Co., Ltd.), Ebicure 3255, 4255 (trade names manufactured by Yuka Shell Epoxy Co., Ltd.); Tomide 238 and Fujicure 202, which are generally commercially available as amine adducts (trade names manufactured by Fuji Kasei Co., Ltd.) company product name), Adeka Hardener EH-53
1 (trade name manufactured by Asahi Denka Co., Ltd.): Sanmide T-100 and D-100, which are generally commercially available as aliphatic polyamines.
, P-100 (trade names manufactured by Sansho Kagaku Co., Ltd.); Evomate B-002 and C- as heterocyclic diamine derivatives;
Typical examples include 002 and S-005 (all trade names manufactured by Ajinomoto Co., Ltd.).

The curing agent, which is component (c), is mixed with components (a) and (b) to form a paint just before use, and the blending ratio is (
0.7 to 1.0% per equivalent of the total of component a) and component (b).
A range of about 3 equivalents is appropriate. Note that when blending the curing agent, it is also possible to add a curing accelerator such as an amine compound. The coating composition of the present invention has been described above (a
), (b) and (c) are essential components, and when used as a paint, various solvents can be used, including aromatic hydrocarbons such as xylene and toluene, and alcohols such as n-butanol. In addition to esters such as butyl acetate, ketones such as methyl isobutyl ketone, glycol ethers such as ethyl cellosolve, various commercially available thinners may also be employed.

Furthermore, various inorganic pigments (sintered pigments, extender pigments,
(including metal pigments, etc.), organic pigments, dispersion stabilizers, viscosity modifiers, leveling agents, anti-gelling agents, ultraviolet absorbers, etc. can be added.

[Effects of the Invention] The coating composition of the present invention can form coating films with excellent adhesion and corrosion resistance on various objects to be coated, especially iron substrates, and is also capable of forming coating films with excellent adhesion and anticorrosion properties on various objects to be coated, especially iron substrates. It also has excellent adhesion, so when repairing or repainting a fluororesin coating, it can be painted on the fluororesin coating without polishing or roughening the coating surface, and the polishing and roughening steps described above can be applied. This eliminates the need for this process, which has great practical value in shortening the process.

Hereinafter, the present invention will be explained in more detail with reference to Examples. In the examples, "parts" and "%" are expressed on a weight basis.

Example 1 Units based on chlorotrifluoroethylene/cyclohexyl vinyl ether/ethyl vinyl ether/glycidyl vinyl ether were 51.0 mol% and 17.0 mol%, respectively.
Fluorine-containing copolymer A containing mol%, 22.5 mol% and 9.5 mol% (in tetrahydrofuran, 30%
36 parts of a 60% xylene solution with an intrinsic viscosity of 0.276 A/g measured at °C, a bisphenol type epoxy resin ["
Epicoat 1001” (trade name manufactured by Yuka Shell Epoxy Co., Ltd.), epoxy equivalent 450-500, non-volatile content 70%]
A mixture consisting of 12 parts of titanium oxide pigment, 15 parts of titanium oxide pigment, talc 15B, 10 parts of precipitated barium sulfate, 1 part of antisettling agent, 5 parts of methyl isobutyl ketone, and 4 parts of quijirole was kneaded to form a main ingredient. Amine adduct resin [Adeka Hardener EH-531J (
A paint was prepared by blending 3.4 parts of Asahi Denka Co., Ltd. (trade name)].

Examples 2 to 6 and Comparative Examples 1 to 3 Paints were prepared in the same manner as in Example 1 using the formulations consisting of the main component and curing agent component shown in Table 1.

The following tests were conducted on the paints obtained in Examples 1 to 6 and Comparative Examples 1 to 3, and the results are shown in Table 2.

Experimental Example 1 The paints obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were #2
Polished with 40 emery paper and degreased with Kijiroll (JIS G3141.150 x 70 x 0.8 mm)
) with a brush so that each coat has a dry film thickness of 50 μm, and dried at room temperature for - weeks, followed by initial adhesion tests (row cut, cellophane tape peeling test) and salt water spray tests (JIS G5400). ) An adhesion test was conducted after 500 hours, and the results are shown in Table 2.

Experimental Example 2 The paint of Comparative Example 2 was applied to a chromate-treated aluminum plate by air spray to a dry film thickness of 30 μm, and -
It was dried at room temperature for a week. Examples 1-
6 and Comparative Examples 1 to 3 with a dry film thickness of 50 μm.
After drying at room temperature for -1 week, the initial adhesion test and the adhesion test after the salt spray test were conducted in the same manner as in Experimental Example 1, and the results are shown in Table 2.

Experimental Example 3 The painted board of Experimental Example 2 coated with the paint of Comparative Example 2 was subjected to an outdoor natural atomization test for 6 months, and then the stains on the painted board surface were removed with a cloth moistened with Kijiroll, and the same procedure as in Experimental Example 2 was carried out. The coatings of Examples 1 to 6 and Comparative Examples 1 to 3 were applied to the coatings, and an initial adhesion test was conducted. The results are shown in Table 2.

As is clear from Table 2, the coatings of Examples 1 to 6 obtained from the coating compositions of the present invention can be applied directly to mild steel plates or on fluororesin coatings. All had excellent adhesion.

On the other hand, in Comparative Example 1, which is a conventional epoxy resin-based paint, and Comparative Example 2, which is a fluororesin-based paint with an excess of epoxy resin, those applied directly to a mild steel plate had excellent adhesion; When applied onto a system coating, interlayer peeling occurred and adhesion was poor.

Furthermore, in Comparative Example 3, which is a conventional fluororesin paint without an epoxy group, when it was directly applied to a mild steel plate, the adhesion was somewhat poor, and the corrosion resistance was also poor.

Claims (1)

Scope of Claims: (a) a solvent-soluble fluorine-containing copolymer having an epoxy group as a curing-reactive site in the molecule; (b) an epoxy resin; and (c) a curing agent; ) per 100 parts by weight of component (b)
A coating composition comprising 1 to 100 parts by weight of the components.