JPS6236073B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is applicable to the interior of a steel ship, for example, a ballast tank, a void space, a coffer dam,
The present invention relates to an anticorrosive coating composition for use on low-grade base-treated surfaces to prevent corrosion of holds, chain rockers, etc. (Prior art) There are anticorrosion paints for the interior of ships that use epoxy resins, polyurethane resins, vinyl resins, chlorinated rubber, etc. and bituminous substances as coloring agents, and these paints have water resistance, salt water resistance, and corrosion resistance. It is excellent and widely used. Two-component paints such as coal tar epoxy paints and coal tar urethane paints are particularly popular. (Problem to be solved by the invention) However, in order for these paints to exhibit sufficient performance, careful preparation of the substrate is required, such as sandblasting SIS Sa2.5 or power tool treatment SIS.
St3 etc. is required. Furthermore, the interior of a ship has a complex structure and poor footing, and it is sometimes necessary to erect scaffolding to ensure work safety, and the careful preparation of the surface described above requires a great deal of effort and time. The reality is that it costs money. Furthermore, coal tar epoxy paints have drawbacks such as slow drying at low temperatures, and coal tar urethane paints cause foaming at high temperatures, so it is necessary to use both depending on the temperature. As an anti-corrosion paint that can be applied with simple preparation of the substrate,
Prior to the present invention, there was a one-component anticorrosive coating composition (Japanese Patent Application No. 138917/1982) containing a modified epoxy resin and a bituminous substance as main color vehicles (hereinafter referred to as the "original invention"). Although the original invention ensured corrosion resistance on low-grade substrate treated surfaces, the time required for complete curing was long, and it could not match the current coating process in shipyards, etc., especially in the winter. An object of the present invention is to improve drying properties without impairing the corrosion resistance of the original invention. Another object is to provide a two-component anticorrosive paint that can be applied year-round with the same paint. (Means for Solving the Problems) As a method for improving drying properties without impairing the corrosion resistance of the original invention, by crosslinking with a polyisocyanate compound using the alcoholic hydroxyl groups of a modified epoxy resin, Also, sufficient drying properties can be obtained, and adhesion can also be improved.
Furthermore, by slightly adjusting the reaction equivalent ratio of alcoholic hydroxyl groups and isocyanate groups, foaming can be suppressed even in high temperature periods, and the present invention was completed based on the discovery that the coating can be applied throughout the year. The polyhydric phenol-modified epoxy resin having adjacent hydroxyl groups used in the present invention penetrates into the rust composed of iron hydroxide, iron oxide, etc. generated on the surface of the steel material to be coated, forms a chelate with the rust, and eliminates the rust. It has an enveloping and stabilizing effect. The state of this chelate formation is shown in Formula-1. Furthermore, the polyvalent phenol group of the modified epoxy resin has reducing properties, and has the effect of converting active red rust into stable black rust and inhibiting the progress of rust, as shown in Formula-2. Modified epoxy resin has the general formula (However, R ₁ ; H or CH ₃ , R ₂ ; -CH ₂ - or

[Formula] A high molecular weight product obtained by reacting an epoxy resin represented by n; 3 to 200) with a polyhydric phenol carboxylic acid polyhydric alcohol ester having adjacent hydroxyl groups or a polynuclear polyhydric phenol having adjacent hydroxyl groups in a solvent. It is a reaction product. In order to bond a polyhydric phenol group having adjacent hydroxyl groups to an epoxy resin, a polyhydric phenol polyhydric alcohol ester having adjacent hydroxyl groups or (and/or) a condensate of a polyhydric phenol having adjacent hydroxyl groups and formalin is added to a solution. Inside, react with epoxy resin. Examples of polyhydric phenol polyhydric alcohol esters having adjacent hydroxyl groups include ethylene glycol, propylene glycol, butylene glycol, 1.
Polyhydric alcohols such as 6-hexanediol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, and glucose, and catechol-3-carboxylic acid, catechol-4-carboxylic acid, gallic acid, m-digallic acid, and pyrogallol.
Ester compounds in any combination with polyhydric phenol carboxylic acids such as 4-carboxylic acid, pyrogallol-4,6-dicarboxylic acid, and tannic acid can be used, but when these are reacted with an epoxy resin, salicylic acid ester , mononuclear phenol carboxylic acid ester such as P-hydroxybenzoic acid ester may be mixed. Examples of polynuclear polyhydric phenol compounds having adjacent hydroxyl groups include catechol, catechol-3 (or 4)-carboxylic acid (or its esterified product), pyrogallol, pyroganol-4-carboxylic acid (or its esterified product), pyrogallol-4. 6
- dicarboxylic acid (or its esterified product),
Formalin condensates such as 3,4,5-trioxybenzoic acid (or its ester), tannic acid (or its ester), and urushiol are used. Furthermore, when polyhydric phenol is condensed with formalin, mononuclear phenols such as phenol, cresol, hydroquinone, and salicylic acid may be mixed. As such a modified epoxy resin, for example, Asahi Denka Kogyo Co., Ltd.'s Adekal Resin EPX-881 (trade name)
It is preferable to use one having a weight average molecular weight of 10,000 to 100,000. If the weight average molecular weight is low, such as 10,000 or less, the drying properties of the paint in which a bituminous substance is used in combination are extremely poor, so it is necessary to crosslink it at high density using a curing agent. In this case, cohesive failure is likely to occur within the rust layer because the shrinkage stress generated during curing of the coating film becomes large and the strength of the coating film exceeds the strength of the rust layer. On the other hand, if the molecular weight is 100,000 or more, the paint will have a high viscosity and will have poor spray workability, making it difficult to obtain a high-quality thick film. Therefore, the molecular weight is most preferably in the range of 30,000 to 60,000. The larger the molecular weight of the modified epoxy resin, the better the drying properties and physical properties of the coating film, but the coating composition that uses a bituminous substance in combination still has insufficient drying properties in cold weather, which is the drawback of the original invention. Since drying properties can be improved by slight crosslinking in the high molecular weight range, cohesive failure within the rust layer that occurs in the case of high density crosslinking in the low molecular weight range can be prevented. For crosslinking, it is preferable to react a polyisocyanate compound that can react even in cold weather with the alcoholic hydroxyl group of the modified epoxy resin. There is also a method of crosslinking with polyamine or polyamide using the epoxy group at the end of modified epoxy resin, but if the modified epoxy resin is a polymer, the concentration of epoxy groups is low and the reaction in cold weather is extremely slow, making it impractical. The improvement in drying performance is immeasurable. Examples of the polyisocyanate compounds used in the present invention include commercially available curing agents for polyurethane resin paints, curing agents for various urethane molding resins, and moisture-curable paints (polyisocyanates).
Any polyisocyanate compound having more than one isocyanate group in one molecule can be used. The amount of the polyisocyanate compound to be added to the modified epoxy resin is not particularly limited as the appropriate amount varies depending on the isocyanate group content and reactivity in the polyisocyanate compound, but the amount of hydroxyl groups in the modified epoxy resin and the isocyanate in the polyisocyanate compound is The reaction equivalent ratio of the groups is 1:
The balance between dryness and foaming prevention can be determined within the range of 0.2 to 1:1.0. During high-temperature periods, when a thick film is applied, the isocyanate group reacts with rust, paint, moisture contained in the atmosphere, etc., and is likely to generate carbon dioxide gas. and isocyanate groups (1:0.2 to 1:0.6), drying properties can be ensured and the foaming phenomenon can be prevented. Since the reactivity is relatively slow in the cold season, in order to ensure dryness, approximately twice as much polyisocyanate compound as in the high temperature season is added (the reaction equivalent ratio of hydroxyl groups and isocyanate groups is 1:0.4).
~1:1.0), but there is no foaming phenomenon.
When the reaction equivalent ratio is less than 1:0.2 or more than 1:1.0, it is difficult to improve the drying property or prevent the floating phenomenon even if the type of polyisocyanate compound is changed. Conventionally, coal tar epoxy paints dry slowly in the winter, and coal tar urethane paints foam in the summer, so it was necessary to use these two types of paints depending on the temperature, but with the present invention, By slightly adjusting the amount of polyisocyanate compound added to one type of paint, it has become possible to paint throughout the entire season. Another advantage of the present invention is that it has improved adhesion compared to the original invention. Bituminous substances used to improve waterproofness can be roughly divided into those made from petroleum and those made from coal. The latter has excellent properties such as waterproofness, hardness, and caking properties, and among them, so-called swollen coal, which is made by swelling coal powder with a mixture of coal tar and coal tar pitch at a high temperature of 300°C or higher, is most preferable.
The mixing ratio with the modified epoxy resin is most preferably 30 to 600 parts per 100 parts of the modified epoxy resin in order to balance chelate forming ability and waterproofness.
60 to 400 parts is preferred. Other ingredients used in the present invention include extender pigments such as mica, talc, and barium sulfate, coloring pigments such as iron oxide, anti-sagging/settling agents such as zinc phosphate, aromatic solvents, ketone solvents, At least two organic solvents selected from alcohol solvents, ester solvents, and cellosolve solvents, and dehydrating agents such as silica/alumina gel and orthoformate esters can be used. The paint can be prepared using a dispersion device such as a three-roll mill, a ball mill, or a sand grind mill, and immediately before use, it is mixed with a polyisocyanate compound varnish and applied by conventional painting methods such as brushing, rolling, or spraying. It can be painted. In addition to the interior of steel ships mentioned above, it is also used as an anticorrosive coating for the low-grade surface treated surfaces of steel structures such as oil storage tanks, various onshore plants, and bridge girders. (Effects of the Invention) (1) The polyvalent phenol group having adjacent hydroxyl groups in the modified epoxy resin forms a chelate with rust to stabilize the rust. (2) The polyvalent phenol group having adjacent hydroxyl groups in the modified epoxy resin has reducing properties and also has the effect of converting red rust into stable black rust. (3) By crosslinking the modified polymeric epoxy resin with a small amount of polyisocyanate compound, drying performance is improved and the stress applied to the rust layer can be minimized, thereby preventing agglomeration from within the rust layer. Peeling can be prevented. (4) By slightly adjusting the amount of polyisocyanate compound added, it was possible to achieve dryness in cold seasons and prevention of foaming in hot seasons, making it possible to use the same anticorrosion paint all year round. (5) The bituminous material used in combination has excellent waterproof and permeation resistance, and prevents the penetration of water, oxygen, and salts that promote rust. With the functions (1), (2), (3), (4), and (5), it is possible to use the anticorrosive paint for a long time throughout the year with simple preparation of the substrate. (Example) Examples and comparative examples of the present invention are shown in Attached Table-1. Adjustment of paint: Comparative Example 3 and Examples 1, 2, 3, and 4 had 3 main ingredients.
Prepared using this roll. In Comparative Examples 1 and 2 and Examples 1, 2, 3, and 4, predetermined amounts of the main ingredient and curing agent were sufficiently stirred and mixed before use. Evaluation of coating film: Regarding drying properties and foaming, the coatings of comparative examples and examples were applied to polished plate glass using a doctor blade so that the dry film thickness was 200 μm, and the temperature and relative humidity were 5°C and 70%, respectively. It was dried and evaluated under two conditions: 30°C and 80%. Regarding the paint film performance, the size was determined by being exposed outdoors for 6 months to develop rust.
The dry film thickness of the above paint was applied to a 1.6 x 70 x 150 mm steel plate.
Spray coated to a thickness of 200 μm, dried at room temperature for 10 days, and immersed in 3% saline solution at room temperature for 6 months to determine rust prevention, blistering, adhesion, impact resistance, and 50℃
After a two-month test in a high temperature, high humidity, zero atmosphere with a relative humidity of 98%, blistering, adhesion, and impact resistance were evaluated. The evaluation results are shown in Attached Table-2.

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Claims (1)

[Claims] 1 (a) General formula (However, R ₁ ; H or CH ₃ , R ₂ ; -CH ₂ - or [Formula] n; 30 to 200) and a polyvalent phenol carboxylic acid polyhydric alcohol ester having an adjacent hydroxyl group or an adjacent A high molecular weight reaction product obtained by reacting a polynuclear polyhydric phenol having a hydroxyl group in a solvent (hereinafter simply referred to as "modified epoxy resin"), (b) a bituminous substance, and (c) 1 in 1 molecule. An anticorrosive paint composition for the interior of a ship for a low-grade base-treated surface, which uses a polyisocyanate compound having more than 3 isocyanate groups as a color vehicle. 2. In claim 1, the polyhydric phenol polyhydric alcohol ester having adjacent hydroxyl groups includes ethylene glycol, propylene glycol, butylene glycol, 1,6-hexanediol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, Polyhydric alcohol of glucose, catechol-3-carboxylic acid, catechol-4-carboxylic acid, gallic acid, m
-digallic acid, pyrogallol-4-carboxylic acid,
An anticorrosive coating composition characterized by being an ester compound of any combination of pyrogallol-4,6-dicarboxylic acid and tannic acid with polyhydric phenolcarboxylic acid. 3 In claim 1, the polynuclear polyhydric phenol having adjacent hydroxyl groups refers to catechol, catechol-3 (or 4)-carboxylic acid (or its esterified product), pyrogallol, pyrogallol-4-carboxylic acid (or its ester), esterified product), pyrogallol-4,6-dicarboxylic acid (or its esterified product), 3,4,5-trioxybenzoic acid (or its esterified product), tannic acid (or its esterified product), formalin condensate of urushiol An anticorrosive paint composition characterized by: 4. The anticorrosive coating composition according to claim 1, characterized in that 30 to 600 parts of a bituminous substance is mixed with 100 parts of a modified epoxy resin. 5 In claim 1, the reaction equivalence ratio between the hydroxyl groups in the modified epoxy resin and the isocyanate groups in the polyisocyanate compound is 1:0.2.
-1:1 anticorrosive coating composition.