WO2021014492A1 - Anticorrosive filler used in organic paint, anticorrosive filler manufacturing method, and paint - Google Patents

Abstract

Provided is an anticorrosive filler for paint that improves the addition and release of layered double hydroxides that constitute an anticorrosive filler for paint. An anticorrosive filler, which is for organic paint and filled with an anionic corrosion inhibitor, is added to an anticorrosive material the particle diameter of which is reduced by irradiation with ultraviolet rays A and the surface of which is modified with a silane compound agent.

Description

Anticorrosion fillers used for organic paints, manufacturing methods and paints for anticorrosion fillers

The present invention relates to a technique for preparing a layered double hydroxide used as a filler for an anticorrosion protective coating material.

Layered double hydroxides (LDH), known as anionic clays, consist of a positively charged metal hydroxide sheet with interchangeable anions and water molecules in the interlayer space. The layered double hydroxide is represented by the following general formula.

Here, M ²⁺ and M ³⁺ are each divalent and trivalent metal cations, A ^n-is an anion of valence n, x is defined as the molar ratio of the trivalent cation to total cations ( Patent Document 1: EP2263976A1).

Since the anions in the interlayer space of the layered double hydroxide are not localized, they can be exchanged with other anion species. Therefore, there is great interest in a wide range of applications, for example, removal of NOx and SOx from the exhaust gas of coal-fired power plants (Patent Document 2: US5116587A), removal of dyes from wastewater (Patent Document 3: CN103159328B). And water purification (Patent Document 4: WO2015193087A1) is known.

It has also been found to be used in the protective paint industry because it is effective in storing anionic corrosion-preventing species for on-demand release when exposed to aggressive electrolyte conditions (Patent Document 5: US7578878B2). ..

There are various synthetic methods for the preparation of layered double hydroxide structures, including coprecipitation, hydrothermal, sol-gel, microwave and urea hydrolysis. However, the coprecipitation method is the simplest and most widely accepted for the synthesis of layered double hydroxides. Utilizing this method, a homogeneous precursor in which two or more precursors are closely mixed is used as a starting material (Non-Patent Document 1).

On the other hand, UV light can generate hydroxyl-free radicals that have been shown to promote zeolite crystallization (Non-Patent Document 2). Furthermore, UV irradiation has been shown to have a significant effect on the size of synthetic materials, such as silver (Non-Patent Document 3), indium nitride (Non-Patent Document 4), and reduced graphene oxide zinc oxide nanorod composites (Non-Patent Document 3). Non-patent document 5) is known.

European Patent Application Publication No. 2233976 U.S. Pat. No. 5,116,587 Chinese Patent No. 103159328 International release 2015/19 3087 U.S. Pat. No. 7578878

By the way, we have found that in the absence of UV irradiation, the particle size is usually large (5-10 microns) and contains aggregation, so the induction of UV light is smaller particle size (1-3 microns) and less aggregation. Found that can bring.

An object of the present invention is to prepare a layered double hydroxide by ultraviolet irradiation in order to improve the addition and release of layered double hydroxides constituting the anticorrosion filler for paints. The purpose is to provide a method for producing an agent and a paint.

The present invention is an ultraviolet assisted synthesis method for preparing a layered double hydroxide (LDH), which is an anticorrosive filler for preventing corrosion of paint, and is used as a method used for preparing a layered double hydroxide structure. Various synthetic methods are exemplified, including precipitation, hydrothermal, sol-gel, microwave and urea hydrolysis.

After the synthesis process is complete, the surface chemistry of the particles is modified by the appropriate surface modifier, resulting in ion exchange with corrosion-suppressing anions. The main synthetic method is the coprecipitation method. After the addition of divalent and trivalent cations and pH adjustment, the suspension is exposed to ultraviolet A waves (UV-A). After completion of the synthesis process, the surface chemistry of the particles is modified by a suitable surface modifier, resulting in ion exchange with corrosion-suppressing anions (anions).

The advantages presented by the present invention are:
1. 1. The particle size of the layered double hydroxide is small, and it is suitable for the preparation of corrosion-preventive paint (rust-preventive paint).
2. 2. The high crystal structure of the synthesized layered double hydroxide is a good choice for the addition and release of anionic corrosion inhibitors.
3. 3. Subsequent surface treatment with a surface modifier enhances compatibility with the polymeric coating and makes it easily dispersible.

The paints of Reference Example 1 and Example 1 prepared according to the formulation shown in Table 1 were applied to a metal plate, and a sample having an X-shaped scratch (scribe) was exposed to salt water, and the sample after 500 hours had passed. (A) is Reference Example 1, (b) is S / LDH, and (c) is S / UV-LDH. The paints of Reference Example 2 and Example 2 prepared according to the formulation shown in Table 2 were applied to a metal plate, and a sample having an X-shaped scratch (scribe) was exposed to salt water, and the sample after 500 hours had passed. (A) is Reference Example 2, (b) is S / LDH, and (c) is S / UV-LDH.

The method of the present invention will be described below.
A) Synthesis of layered double hydroxides (hereinafter referred to as UV-LDH) supported by ultraviolet rays (UV) The present invention is supported by ultraviolet rays to prepare layered double hydroxides used as corrosion inhibitors for coatings. Synthesize. The main synthetic method of LDH is the coprecipitation method. Divalent cations (preferably, but not limited to, Zn ²⁺ and Mg ²⁺ ) and trivalent cations (preferably, but not limited to) in the form of salts (preferably nitrates, but not limited to). , Al ³⁺ ) to water (preferably deionized water, preferably distilled water).

In the general formula of the layered double hydroxide (anticorrosion substance) shown in the above formula (1), in the formula (1), M ²⁺ is at least one selected from the group consisting of Zn ²⁺ , Mg ²⁺ , or Ni ²⁺ . represents one metal ^{ion, M 3+} is ^{Al 3+,} Fe ^3+, represents at least one kind of metal ion selected from the group consisting of ^{Cr 3+, a n-} is _{^{OH -, Cl -, NO 3}} - , _CO ³ 2-, represent at least one kind of n dianion is selected from the group consisting of _SO ^{4 2-.} m represents the amount of hydrated water.

The concentration of the salt having a divalent cation in the solution of LDH is 0.5-2.5 mol, and the molar ratio (x) of the trivalent to divalent cation is preferably 0.4-0.6. is there. The pH of the solution is adjusted to pH 9.5 ± 0.5 with an alkaline solution (preferably 10% sodium hydroxide, but not limited to).

Next, the suspension is irradiated with ultraviolet A wave (UV-A) and exposed (preferably at least 12 hours). The suspension is then washed with water (preferably deionized water).

Subsequently, the suspension is dried in the oven, or more preferably using a spray dryer. Ultraviolet A wave (UV-A) irradiation aids LDH crystallization and reduces particle size.

B) Surface modification (S / UV-LDH) of UV-exposed LDH (UV-LDH) with an appropriate surface modifier.
Surface modification of UV-exposed layered double hydroxides (UV-LDH) can be performed when organic silane compounds are applied to solvent bases and powder coatings. Surface modifications for application to water-based paints can be ignored. The type of organic silane compound can preferably be selected based on the chemical properties of the paint, for example oxylan or amine functional silanes in epoxy paints, amine or hydroxyl functional silanes in polyurea paints and polyurea paints, vinyl esters. In the paint, vinyl functional silane can be exemplified. However, alkyl, preferably methyl functional silanes, can be used to modify the surface of UV exposed LDH (UV-LDH) for all types of paints.

Surface modification of UV-exposed LDH (UV-LDH) can be carried out directly by the sol-gel method, or preferably by graft polymerization in a solvent medium. The solvent can be selected from a wide range of organic solvents, preferably ethanol or toluene or xylene. A suspension of "ultraviolet exposed LDH (UV-LDH)" particles (preferably 5-30% by weight) in a solution of a silane compound in a solvent (preferably a concentration of 1-10%) at a high temperature (preferably reflux temperature). ) For a certain period of time (preferably at least 12 hours). After cooling the mixed suspension, it is preferably washed with the same solvent and then dried in the oven or more preferably using a spray dryer.

C) Addition of anionic (anionic) corrosion inhibitor (inhibitor) Adjustment of LDH (Inh-S / UV-LDH) The corrosion inhibitor (corrosion inhibitor) added to the surface-modified LDH (S / UV-LDH) is It is selected from a wide range of inhibitory anionic compounds such as phosphates, polyphosphates, molybdenates, vanazine salts, tungstates and the like. The cation moiety of the inhibitory salt can be selected from a wide range of cations, preferably Na ⁺ , K ⁺ , Ba ^{+ 2} .

Surface modifier addition 2-20 wt% solution of corrosion inhibitor (preferably sodium phosphate) in water (preferably deionized water) (corrosion inhibitor) to add LDH (S / UV-LDH) A solution containing) is used. For this purpose, a suspension of surface modifier-added LDH (S / UV-LDH) (1-30% by weight, preferably 10% by weight) is prepared in the inhibitory solution. The suspension is mixed for a period of time (preferably at least 12 hours). After that, it is preferable to wash with deionized water. The suspension is then dried in the oven, or more preferably using a spray dryer.

D) Application to paints The prepared anionic corrosion inhibitor-added LDH (Inh-S / UV-LDH) can be used in the formulation of protective paints as an effective corrosion resistant filler. The recommended amount of this corrosion resistant filler to use is 0.5-5% by weight of all components, depending on the protective coating required. It is also recommended to replace up to 30% by weight. It is recommended to replace up to 30% by weight of the total content of the anticorrosive pigment with LDH (Inh-S / UV-LDH) with anionic corrosion inhibitors, the rest being inert fillers such as talc, calcium carbonate or It is a barite.

Example 1
A Zn-Al phosphate-based LDH surface-modified with aminopropyltriethoxysilane was prepared and added to a solvent-based epoxy paint as follows.

The concentration of Zn (NO ₃ ) _{2 in} the solution is 1 mol, and the molar ratio of Al (NO ₃ ) ₃ to Zn (NO ₃ ) ₂ is 0.5. The pH of the solution is adjusted to 9.5 ± 0.5 with an alkaline solution (sodium hydroxide 10%). The suspension is then exposed for 24 hours by irradiation with ultraviolet A wave (UV-A, 40 W, manufactured by Philips, wavelength 315-400 nm). The suspension is then washed with deionized water. Further, the suspension is dried using a spray dryer.

To prepare a specific suspension, first prepare a 5% by weight solution (silane solution) of aminopropyltriethoxysilane in ethanol, and then use the synthesized LDH (Zn-Al LDH to which phosphate is added). A 15 wt% suspension was prepared in addition to the silane solution.

The prepared suspension was mixed under reflux for 24 hours and then washed with deionized water. The suspension was then dried using a spray dryer.

A 5 wt% solution of sodium phosphate in deionized water was used to dope the surface modified LDH. To this end, a 10 wt% suspension of surface-modified LDH (S / UV-LDH) was prepared in an inhibitory solution. The suspension was mixed for 12 hours and then washed with deionized water. The suspension was then dried using a spray dryer.

Table 1 shows the formulation of the epoxy paint, and Reference Example 1 shows the surface of 20% by weight of the total zinc phosphate content by adding the prepared phosphoric acid in a typical formulation containing 11.3% zinc phosphate. Was replaced with modified Zn—Al LDH, and the rest was replaced with talc (80% by weight). All other conditions, namely surface treatment, dispersion and dry film thickness, paint application and storage treatment, remained the same.

The components of the thickener gel of No. 3 are adjusted with the organic clay thickener shown by No. 11-13, xylene, and methanol in the formulation shown in Table 1. Further, the components of No. 1-10 were used as part A, the polyamide 115 of No. 14 as part B, and the mixing ratio of A: B was 10: 1.

The LDH synthesis procedure was repeated without UV irradiation, and the final sample was represented as S / LDH. The particle sizes of S / LDH and S / UV-LDH were in the range of 5-10 and 1-3 microns, respectively.

In FIG. 1, the paints of Reference Example 1 and Example 1 prepared according to the formulation shown in Table 1 were applied to a metal plate, and a sample having an X-shaped scratch (scribe) was exposed to salt water for 500 hours. The image of the sample after the lapse is shown, (a) is Reference Example 1, (b) is S / LDH, and (c) is S / UV-LDH.

As shown in FIGS. 1B and 1C, the sample coated with the LDH-containing paint of Example 1 did not show any swelling around the region where the X-shaped scratch was formed. However, as shown in FIG. 1 (a), an X-shaped scratch is applied to the sample coated with the paint of Reference Example 1 containing only zinc phosphate (No. 8 in Table 1) as a general anticorrosive pigment. There was swelling and corrosion around the wound.

Example 2
Zn-Al LDHs surface modified with methyltriethoxysilane and filled with molybdate were prepared for solvent-based epoxy coatings as follows.

The concentration of Zn (NO ₃ ) _{2 in} the solution is 1 mol, and the molar ratio of Al (NO ₃ ) ₃ to Zn (NO ₃ ) ₂ is 0.5. The pH of the solution is adjusted to 9.5 ± 0.5 with an alkaline solution (sodium hydroxide 10%). The suspension was then irradiated with ultraviolet A waves (UV-A, 40 W, manufactured by Philips, wavelength 315-400 nm) and exposed for 24 hours. The suspension was washed with deionized water and then the suspension was dried using a spray dryer.

For specific suspension preparation, a 5 wt% toluene solution of methyltriethoxysilane was prepared. The synthesized LDH was added to the silane solution to prepare a 15% by weight suspension. The suspension was mixed under reflux for 24 hours and then washed with deionized water. The suspension was then dried using a spray dryer.

A 5 wt% solution of sodium molybdate in deionized water was used to dope the surface modified LDH. To this end, a 10 wt% suspension of surface-modified LDH (S / UV-LDH) was prepared in an inhibitory solution. The suspension was mixed for 12 hours and then washed with deionized water. The suspension was then dried using a spray dryer.

Table 2 shows the formulation of the epoxy ester paint, and Reference Example 2 is prepared with 11.3% by weight of the total zinc phosphate content in a typical formulation of the epoxy ester paint containing 10% zinc phosphate. The surface was replaced with Zn—Al-based LDH whose surface was modified by adding phosphoric acid, and the rest was replaced with 90% by weight of heavy crystal stone. All other conditions, namely surface treatment, dispersion and dry film thickness, paint application and storage treatment, remained the same.

The LDH synthesis procedure was repeated without UV irradiation, and the final sample was designated as (S / LDH). The particle sizes of S / LDH and S / UV-LDH were in the range of 5-10 and 1-3 microns, respectively.

In FIG. 2, the paints of Reference Example 2 and Example 2 prepared according to the formulation shown in Table 2 were applied to a metal plate, and a sample having an X-shaped scratch (scribe) was exposed to salt water for 500 hours. The image of the sample after the lapse is shown, (a) is Reference Example 2, (b) is S / LDH, and (c) is S / UV-LDH.

As shown in FIGS. 2B and 2C, the sample coated with the LDH-containing paint of Example 2 did not show any swelling around the region where the X-shaped scratch was formed. However, as shown in FIG. 2A, an X-shaped scratch is applied to the sample coated with the paint of Reference Example 2 containing only zinc phosphate (No. 29 in Table 2) as a general anticorrosive pigment. Severe swelling and corrosion were seen around the wound. Further, the sample coated with the paint containing S / UV-LDH shown in FIG. 2 (c) is more corroded than the sample coated with the paint containing the S / LDH anticorrosive pigment shown in FIG. 2 (b). There were few.

Claims (16)

1. Anticorrosive filling used for organic paints in which an anionic corrosion inhibitor is filled in an anticorrosive substance represented by the following formula (1) whose particle size is reduced by irradiation with ultraviolet A wave and whose surface is modified with a silane compound. Agent.
   

   

   In formula (1), M ²⁺ represents at least one metal ion selected from the group consisting of Zn ²⁺ , Mg ²⁺ , or Ni ²⁺ , and M ³⁺ is the group consisting of Al ³⁺ , Fe ³⁺ , and Cr ^3+. represents at least one kind of metal ion selected ^{from, a n-is _{OH -, Cl -, NO 3}} -, CO 3 2-, at least one selected from the group consisting of _SO ^{4 2-} Represents the n-valent anion of. x is 0.4 or more and 0.6 or less, and m is the amount of hydrated water.
2. In the anticorrosion filler according to claim 1,
   The silane compound is an anticorrosion filler characterized by being an alkyl, preferably a methyl functional silane.
3. In the anticorrosion filler according to claim 1,
   The anticorrosion filler, wherein the anionic corrosion inhibitor is any one selected from the group consisting of phosphate, polyphosphate, molybdate, vanadate, and tungstate.
4. In the anticorrosion filler according to claim 3,
   An anticorrosive filler characterized in that the cationic portion of the anionic corrosion inhibitor is any one selected from the group of Na ⁺ , K ⁺ , and Ba ^{+ 2} .
5. A method for manufacturing an anticorrosion filler used in organic paints.
   The first step of irradiating a suspension in which an anticorrosive substance represented by the following formula (2) is added to water or deionized water with ultraviolet A wave for a predetermined time and exposing the anticorrosive substance with ultraviolet rays.
   The second step of surface-modifying the UV-exposed anticorrosive substance by a sol-gel method or graft polymerization in a solvent medium, and
   The third step, in which the surface-modified anticorrosive substance is added to an inhibitory solution containing a corrosion inhibitor and mixed.
   A method for producing an anticorrosion filler having and.
   

   

   In formula (2), M ²⁺ represents at least one metal ion selected from the group consisting of Zn ²⁺ , Mg ²⁺ , or Ni ²⁺ , and M ³⁺ is the group consisting of Al ³⁺ , Fe ³⁺ , and Cr ^3+. represents at least one kind of metal ion selected ^{from, a n-is _{OH -, Cl -, NO 3}} -, CO 3 2-, at least one selected from the group consisting of _SO ^{4 2-} Represents the n-valent anion of. m represents the amount of hydrated water. x is 0.4 or more and 0.6 or less.
6. In the method for producing an anticorrosion filler according to claim 5.
   In the graft polymerization in the solvent medium of the second step, a suspension of the anticorrosive substance exposed to ultraviolet rays in a solution of a silane compound in an organic solvent is mixed at a reflux temperature, cooled, washed and dried to obtain the ultraviolet rays. A method for producing an anticorrosive filler, which comprises surface modification of an exposed anticorrosive substance.
7. In the method for producing an anticorrosion filler according to claim 5.
   A method for producing an anticorrosion filler, which comprises washing each of the anticorrosion substances with water or deionized water and drying them after the completion of the first step and the third step.
8. In the method for producing an anticorrosion filler according to any one of claims 5 to 7.
   The corrosion inhibitor used in the third step is sodium phosphate, and the surface is modified with an inhibitory solution in which the sodium phosphate is dissolved in water or deionized water in a concentration range of 2 to 20 wt%. A method for producing an anticorrosive filler, which comprises adding an anticorrosive substance.
9. In the method for producing an anticorrosion filler according to claim 8.
   A method for producing an anticorrosion filler, which comprises preparing a suspension of the surface-modified anticorrosion substance in the inhibitory solution in the second step, which contains 1 to 30 wt% of the anticorrosion substance with respect to the silane solution. ..
10. In the method for producing an anticorrosion filler according to any one of claims 6 to 9.
    The organic solvent is any one selected from the group consisting of ethanol, toluene or xylene and is a suspension having 5 to 30 wt% anticorrosive material in a silane compound solution in a solvent having a concentration of 1 to 10%. A method for producing an anticorrosion filler, which comprises adding a liquid to the inhibitory solution.
11. In the method for producing an anticorrosion filler according to any one of claims 5 to 10.
    The suspension in the first step has a concentration of a salt having a divalent cation in the solution of 0.5 to 2.5 mol, and the pH is adjusted to 9.5 ± 0.5 by an alkaline solution. A method for producing an anticorrosion filler.
12. In the method for producing an anticorrosion filler according to any one of claims 5 to 11.
    A method for producing an anticorrosion filler, wherein the ultraviolet A wave has a wavelength of 315 to 400 nm and exposes the suspension for 12 to 24 hours.
13. A solvent-based, water-based or powder-based paint filled with the anticorrosion filler according to any one of claims 1 to 4.
14. In the paint according to claim 13,
    The silane compound of the anticorrosion filler is a paint characterized by being an oxylane or amine functional silane in an epoxy paint, an amine or hydroxyl functional silane in a polyurethane paint and a polyurea paint, and a vinyl functional silane in a vinyl ester paint. ..
15. In the paint according to claim 13 or 14.
    The anticorrosion filler is a paint characterized by being 0.5 to 5% by weight of the total composition of the paint.
16. In the paint according to any one of claims 13 to 15.
    The coating material is characterized in that the anticorrosion filler replaces up to 30% by weight of the total content of the anticorrosion pigment, and the rest is talc, calcium carbonate or barite which is an inert filler.

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