Inorganic silicon modified waterborne corrosion-inhibiting and anticorrosive coating containing functional polysiloxane, and preparation method and application thereof

Abstract

The application discloses an inorganic silicon modified water-based corrosion and rust prevention paint containing functional polysiloxane as well as a preparation method and application thereof. The paint contains, in parts by weight, 30-60 parts of a water-based hybrid acrylic emulsion, 1-15 parts of functional polysiloxane, 5-25 parts of inorganic silicon-based corrosion inhibitor filler, 10-40 parts of pigment and filler, 1-5 parts of water-based additive, and the balance of water. The functional polysiloxane is amino or silanol / alkoxy functionalized polysiloxane emulsion; and the inorganic silicon-based corrosion inhibitor filler is a combination of calcium ion exchange type silica gel pigment and calcium silicate. The inorganic hybrid emulsion, the functional polysiloxane and the inorganic silicon corrosion inhibitor pigment are compounded to endow the coating with excellent physical shielding property, active corrosion inhibition and surface hydrophobicity, realize fast drying, high hardness, excellent water and salt fog resistance and long-acting corrosion prevention performance, and especially can adapt to the harsh requirements of marine environment for the water-based corrosion prevention paint, which has important significance for the development of the shipbuilding industry.

Description

Technical Field

[0001] This invention belongs to the field of anti-corrosion coatings, and relates to an inorganic silicon-modified waterborne corrosion-inhibiting anti-corrosion coating containing functional polysiloxane, its preparation method, and its application. Background Technology

[0002] In the harsh marine environment, ships and their marine engineering structures are subjected to long-term erosion from high salt spray, high humidity, strong ultraviolet radiation, and wave erosion, placing extremely stringent demands on the performance of anti-corrosion coatings. While traditional solvent-based heavy-duty anti-corrosion coatings are reliable, their high VOC emissions pose a threat to the confined environment of ship cabins and port air quality, leading to increasing restrictions. Existing water-based anti-corrosion coatings, although environmentally friendly, often fail to fully meet the requirements for heavy-duty corrosion protection in the marine field due to limitations in salt water immersion resistance, impermeability, film density, and long-term weather resistance. Issues such as flash rust, slow drying, and poor tolerance to complex steel structure surface treatments, particularly during high-humidity application, limit their widespread use in critical areas such as ship primers, ballast tanks, and decks.

[0003] Currently common waterborne anti-corrosion coating systems include waterborne acrylic, waterborne alkyd, waterborne epoxy ester, two-component waterborne epoxy, and two-component waterborne polyurethane. However, these systems still have some shortcomings: for example, single-component waterborne acrylic coatings are prone to flash rust and tackiness under high temperature and humidity conditions, and their hardness build-up is slow; waterborne alkyd and epoxy ester coatings have slow drying speeds and low hardness; while two-component systems have better performance, they suffer from limited activation periods, inconvenient application, and higher costs. To address these issues, researchers have attempted to modify waterborne resins with inorganic materials or use novel corrosion-inhibiting pigments. For example, inorganic silicon-based corrosion-inhibiting pigments (such as calcium ion-exchange silica gel pigments and calcium silicate) are being used to replace traditional rust-inhibiting pigments containing heavy metals or with poor stability, and waterborne hybrid acrylic emulsions are being used as film-forming agents to improve the coating's fast drying, hardness, water resistance, and anti-corrosion performance.

[0004] Polysiloxanes, due to their unique Si-O-Si main chain structure, possess excellent high and low temperature resistance, weather resistance, UV resistance, low surface energy, high hydrophobicity, and good biocompatibility. Introducing polysiloxanes into coating systems is expected to significantly improve the coating's weather resistance, hydrophobicity, stain resistance, and flexibility. However, a mature solution has yet to be found for effectively and stably combining polysiloxanes with water-based inorganic modified systems (especially systems containing inorganic corrosion inhibitors and inorganic hybrid emulsions) and leveraging their synergistic effects to enhance the overall corrosion resistance of coatings.

[0005] Therefore, developing a water-based anti-corrosion coating that combines environmental friendliness, ease of application, and excellent long-lasting protective performance, especially one that can meet the harsh requirements of the marine environment, is of great significance for the sustainable development of the shipbuilding industry. Summary of the Invention

[0006] The technical problem to be solved by this invention is to overcome the shortcomings of existing water-based anti-corrosion coatings in terms of drying speed, hardness, tackiness, long-term water and salt spray resistance, and film density. This invention provides an inorganic silicon-modified water-based corrosion-inhibiting anti-corrosion coating containing functional polysiloxane, which has low VOC content, is free of heavy metals, dries quickly, has high hardness, excellent water and salt spray resistance, and especially enhances film density and hydrophobicity, as well as long-term anti-corrosion performance, along with its preparation method.

[0007] To achieve the above-mentioned goals, the present invention provides an inorganic silicon-modified waterborne corrosion-inhibiting coating containing functional polysiloxane, wherein the raw material components, by weight, include:

[0008] Waterborne hybrid acrylic emulsion: 30-60 parts (based on solids content); functional polysiloxane: 1-15 parts (based on solids content); inorganic silicon-based corrosion inhibitor filler: 5-25 parts; pigments and fillers: 10-40 parts; waterborne additives: 1-5 parts; water: balance, to 100 parts.

[0009] Preferably, the solid content of the aqueous hybrid acrylic emulsion is 40-55 wt%.

[0010] More preferably, the aqueous hybrid acrylic emulsion is RJ-630 aqueous hybrid acrylic emulsion.

[0011] Preferably, the functional polysiloxane is selected from at least one of the following: amino-functionalized polysiloxane emulsions or aqueous dispersions; silanol or alkoxy-functionalized polysiloxane emulsions or aqueous dispersions.

[0012] The amino-functionalized polysiloxane emulsion or aqueous dispersion is specifically Shin-Etsu KF-8010. The silanol or alkoxy-functionalized polysiloxane emulsion or aqueous dispersion is specifically SILRES® BS 4004.

[0013] These functional groups in functional polysiloxanes help the polysiloxanes to physically entangle or chemically crosslink with components in aqueous hybrid acrylic emulsions or coatings, improving their compatibility and stability in the system, and enhancing the crosslinking density and performance of the coating film.

[0014] Preferably, the inorganic silicon-based corrosion inhibitor filler is selected from at least one of the following: calcium ion-exchange silica gel pigment; calcium silicate; calcium silicate phosphate.

[0015] More preferably, the inorganic silicon-based corrosion inhibitor filler comprises at least two combinations selected from calcium ion-exchange silica gel pigments, calcium silicate, and calcium silicate phosphate.

[0016] Particularly preferred is that the inorganic silicon-based corrosion inhibitor is a combination of calcium ion-exchange silica gel pigment and calcium silicate. The weight ratio of calcium ion-exchange silica gel pigment to calcium silicate is 1:3 to 3:1.

[0017] This invention preferably employs a combination of at least two different types of inorganic silicon-based corrosion inhibitors (calcium ion-exchange silica gel pigment and calcium silicate). Calcium ion-exchange silica gel pigment can rapidly release calcium ions, providing timely passivation and pH buffering at the initial stage of corrosion or at the site of paint film damage, effectively inhibiting the spread of rust at pitting and scratches; while calcium silicate can continuously release silicate ions, reacting with the metal substrate to form a more stable and dense silicate conversion film, providing long-lasting physical shielding and chemical passivation.

[0018] Preferably, the pigments and fillers are selected from at least one of conventional pigments and fillers such as titanium dioxide, iron oxide pigments, mica powder, talc powder, barium sulfate, and kaolin.

[0019] Preferably, the aqueous additive is selected from at least one of wetting agents, dispersants, defoamers, leveling agents, thickeners, film-forming aids, and pH adjusters. Film-forming aids with low VOC or zero VOC are preferred.

[0020] The present invention also provides a method for preparing the above-mentioned coating, comprising the following steps:

[0021] (S1) Add inorganic silicon-based corrosion inhibitors and pigments to water, disperse them at high speed in the presence of wetting agents and dispersants, and grind them to the specified fineness to obtain pigment slurry;

[0022] (S2) Under stirring, the aqueous hybrid acrylic emulsion and functional polysiloxane are added to the pigment slurry obtained in (S1);

[0023] (S3) Add other water-based additives (such as defoamer, leveling agent, thickener, film-forming agent) and the remaining water in sequence, stir evenly, adjust the viscosity and pH value according to actual needs, filter, and the coating is obtained.

[0024] The coating prepared by this invention is environmentally friendly, easy to apply, and has excellent long-lasting protective properties. In particular, it is a water-based anti-corrosion coating that can meet the harsh requirements of the marine environment.

[0025] Compared with the prior art, the present invention has the following significant advantages:

[0026] (1) This invention organically combines inorganic silicon-based corrosion inhibitors, water-based hybrid acrylic emulsions, and functional polysiloxanes. Functional polysiloxanes can be better dispersed and may participate in the film-forming process, filling the micropores of the paint film and forming a denser physical barrier. At the same time, their low surface energy and hydrophobicity significantly reduce the penetration of water and corrosive media. Inorganic silicon corrosion inhibitors play a corrosion-inhibiting role at the interface, especially inhibiting corrosion propagation when the paint film is slightly damaged. This multi-effect of "physical shielding enhancement + active corrosion inhibition + surface hydrophobic modification" significantly improves the long-term water resistance and salt spray resistance of the coating, especially the ability to resist corrosion propagation in scratched areas.

[0027] (2) Waterborne hybrid acrylic emulsions have a fast drying speed and high early hardness. The introduction of functional polysiloxanes (especially those that can participate in crosslinking) can further increase the crosslinking density of the coating film, so that the coating can achieve a higher final hardness (up to H or higher) while drying quickly, and effectively improve the problem of high-temperature tackiness. At the same time, the flexibility of polysiloxane segments helps to maintain or improve the flexibility and impact resistance of the coating.

[0028] (3) This invention is a water-based system, and the VOC content can be controlled at a low level (e.g., ≤100 g / L, or even lower). It does not contain toxic heavy metal corrosion inhibitors and meets environmental protection requirements. The coating is a single component, is stable in storage, and is easy to apply. It can be applied using conventional methods such as spraying or brushing.

[0029] (4) This invention introduces specific functional polysiloxanes into a specific waterborne anti-corrosion system comprising inorganic silicon-based corrosion inhibitors and waterborne hybrid acrylic emulsions. It achieves comprehensive effects, particularly in improving film density, hydrophobicity, long-term salt spray resistance, and hardness, while overcoming tackiness. The functional polysiloxanes are not simply physical additives; their functional groups enable them to be more effectively anchored in the system or participate in film formation. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to specific embodiments. It should be noted that the following embodiments are merely illustrative examples of this invention and are not intended to limit the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the protection scope of this invention.

[0031] Unless otherwise stated, all parts used in the examples are by weight.

[0032] Raw materials:

[0033] Water-based hybrid acrylic emulsion, RJ-630, with a solid content of approximately 50%, commercially available from Shenzhen Ruijing New Materials Technology Co., Ltd.

[0034] Water-based acrylic emulsion: Ordinary pure acrylic emulsion, solid content approximately 50%, commercially available, BASF.

[0035] Amino-functional polysiloxane emulsion: Shin-Etsu KF-8010, amino value approximately 0.3 mmol / g (solid content), solid content approximately 50%.

[0036] Non-functional polysiloxane emulsion E (PDMS emulsion): Commercially available, hydroxyl-terminated or non-functionalized, with a solid content of approximately 50%.

[0037] Calcium ion exchange silica gel pigment: HOMAC® LM-50, Lingwei Technology;

[0038] Calcium silicate: Commercially available, with an average particle size of 5-15 μm.

[0039] Titanium dioxide R-902: Commercially available. Mica powder: Commercially available, wet process, 200 mesh.

[0040] Wetting agent: BYK-348. Dispersant: Water-based sodium polyacrylate dispersant. Defoamer: BYK-028. Film-forming aid: Texanol (Dow Chemical). Thickeners and pH adjusters may be added as needed (preferred thickener: associative polyurethane thickener; pH adjuster: AMP-95).

[0041] Coating preparation method:

[0042] (1) According to the formulation of each embodiment or Table 1, add water, wetting agent, dispersant and half of the defoamer into the dispersion tank, stir evenly, add inorganic silicon-based corrosion inhibitor and pigment filler, disperse at high speed (1500-2000 rpm) for 30 minutes, and then grind to fineness ≤40μm through a sand mill to obtain pigment slurry.

[0043] (2) Under low-speed stirring, slowly add (aqueous hybrid acrylic emulsion or aqueous acrylic emulsion) and polysiloxane emulsion to the pigment slurry.

[0044] (3) Then add the remaining additives (film-forming aid, remaining defoamer) in sequence, and adjust to the working viscosity with deionized water. Stir evenly and filter out the material.

[0045] Example 1: By weight, the raw material components of the coating are: water-based hybrid acrylic emulsion: 35 parts (based on solid content); amino-functionalized polysiloxane emulsion: 4.0 parts (based on solid content); calcium ion exchange silica gel pigment: 8 parts; calcium silicate: 7.0 parts; titanium dioxide R-902: 10 parts; water-based additives: 3.5 parts; water: balance, to 100 parts.

[0046] Example 2: By weight, the raw material components of the coating are: water-based hybrid acrylic emulsion: 40 parts (based on solid content); amino-functionalized polysiloxane emulsion: 2.0 parts (based on solid content); calcium ion exchange silica gel pigment: 6 parts; calcium silicate: 5.0 parts; titanium dioxide R-902: 12 parts; water-based additives: 3.8 parts; water: balance, to 100 parts.

[0047] Example 3: By weight, the raw material components of the coating are: water-based hybrid acrylic emulsion: 45 parts (based on solid content); amino-functionalized polysiloxane emulsion: 3.2 parts (based on solid content); calcium ion exchange type silica gel pigment: 10 parts; calcium silicate: 8.0 parts; titanium dioxide R-902: 15 parts; water-based additives: 4.0 parts; water: balance, to 100 parts.

[0048] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the amino-functional polysiloxane is replaced with a conventional non-functional polysiloxane, while the other operations are the same as in Example 1.

[0049] Comparative Example 2: Compared with Example 1, Comparative Example 2 differs in that all inorganic silicon-based corrosion inhibitor fillers were replaced with calcium ion-exchange silica gel pigments. All other operations were the same as in Example 1.

[0050] Comparative Example 3: Compared with Example 1, Comparative Example 3 differs in that all inorganic silicon-based corrosion inhibitors were replaced with calcium silicate. All other operations were the same as in Example 1.

[0051] Comparative Example 4: Compared with Example 1, Comparative Example 4 differs in that all inorganic silicon-based corrosion inhibitors were replaced with zinc phosphate. All other operations were the same as in Example 1.

[0052] Comparative Example 5: Compared with Example 1, Comparative Example 5 differs in that the inorganic silicon-based corrosion inhibitor filler is replaced with 8 parts calcium ion-exchange silica gel pigment and 7 parts zinc phosphate. All other operations are the same as in Example 1.

[0053] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that the aqueous hybrid acrylic emulsion is replaced with an aqueous acrylic emulsion (ordinary pure acrylic emulsion), and the other operations are the same as in Example 1.

[0054] Table 1:

[0055]

[0056] Performance testing:

[0057] The prepared coating was sprayed onto a Q235 steel plate that had been sandblasted to Sa 2.5 grade, and the dry film thickness was controlled at (60±5) μm. Performance testing was conducted after curing under standard conditions (23±2℃, 50±5% RH) for 7 days.

[0058] Testing standards:

[0059] Surface drying / actual drying time: GB / T 1728-1979;

[0060] Hardness (pencil test): GB / T 6739-2006;

[0061] Adhesion (cross-cut test): GB / T 9286-1998;

[0062] Water resistance: GB / T 1733-1993 (immersion time as required);

[0063] Resistance to neutral salt spray: GB / T 1771-2007 (scratch sample, observe blistering, rusting, peeling and corrosion spread width on both sides of the scratch), 240h, 480h.

[0064] Adhesion test: Place the coated sample in a 50°C oven for 1 hour, then immediately press it with your finger after removing it and observe whether it sticks to your finger or leaves an indentation.

[0065] Contact angle: The static contact angle of a water droplet on a coating surface is determined using a contact angle meter.

[0066] Table 2

[0067]

[0068] Comparative Example 1, by replacing the functional siloxane with a non-functional siloxane, resulted in a decrease in hardness from H to HB, slight tackiness, poorer long-term salt spray resistance (480h blistering and scratch propagation), and a significant reduction in contact angle (95° vs 105°). This demonstrates that the functional groups of polysiloxanes play a crucial role in improving coating hardness, anti-tackiness, enhancing long-term corrosion protection, and improving surface hydrophobicity. Comparative Example 2 used only calcium ion-exchange silica gel pigments, and Comparative Example 3 used only calcium silicate. Compared to Example 1, both showed a significant decrease in neutral salt spray resistance (especially scratch propagation at 240h and overall performance at 480h). Comparative Example 3 (using only calcium silicate) performed particularly poorly. This strongly demonstrates the significant synergistic corrosion inhibition effect of calcium ion-exchange silica gel pigments and calcium silicate in the system of this invention, which is superior to the use of a single component.

[0069] Comparative Example 4 used conventional zinc phosphate instead of the calcium ion-exchange silica gel pigment and calcium silicate combination, while Comparative Example 5 used a combination of calcium ion-exchange silica gel pigment and zinc phosphate. The results showed that the salt spray resistance (especially scratch protection and long-term performance) of Comparative Examples 4 and 5 was inferior to that of Example 1. Although the F+H combination of Comparative Example 5 was superior to the single H in Comparative Example 4, it was still inferior to Example 1. This indicates that the preferred combination of inorganic silicon-based corrosion inhibitors of the present invention, in specific hybrid / functional siloxane systems, has a better anti-corrosion effect than the combination of conventional zinc phosphate or calcium ion-exchange silica gel pigment and zinc phosphate.

[0070] Comparative Example 6, which replaced the hybrid emulsion with a regular pure acrylic emulsion, resulted in slower drying speed, significantly reduced hardness, severe tackiness, poorer water resistance, and a sharp deterioration in salt spray resistance (especially over long periods and at scratched areas), as well as the lowest contact angle. This clearly demonstrates that a high-performance waterborne hybrid acrylic emulsion is one of the fundamental and key components for achieving the excellent fast-drying, high-hardness, anti-tackiness, and strong protective properties described in this invention.

[0071] This invention organically combines a specific waterborne inorganic hybrid acrylic emulsion, a functional polysiloxane, and a preferred calcium ion-exchange silica gel pigment with a calcium silicate composite corrosion inhibitor system. Utilizing their significant synergistic effect, it successfully yields a waterborne corrosion-inhibiting coating with excellent overall performance. While maintaining environmentally friendly characteristics, this coating excels in drying speed, hardness, anti-blocking properties, surface hydrophobicity, and long-term corrosion protection (especially protection of scratched areas), significantly outperforming comparative systems using non-functional siloxanes, single corrosion inhibitors, traditional corrosion inhibitors, or ordinary acrylic emulsions. In particular, this waterborne anti-corrosion coating, capable of meeting the harsh requirements of the marine environment, is of great significance to the development of the shipbuilding industry.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An inorganic silicon-modified water-based anticorrosive coating containing a functional polysiloxane, characterized by, Raw material components by weight parts include: water-based hybrid acrylic emulsion: 30 - 60 parts, by solid content; functional polysiloxane: 1 - 15 parts, by solid content; inorganic silicon-based corrosion inhibitor filler: 5 - 25 parts; pigment filler: 10 - 40 parts; water-based additive: 1 - 5 parts; water: the balance, added to 100 parts; wherein the functional polysiloxane is selected from amino-functionalized polysiloxane emulsion or aqueous dispersion; The inorganic silicon-based corrosion inhibitor filler is a combination of calcium ion exchange type silica gel pigment and calcium silicate; the weight ratio of the calcium ion exchange type silica gel pigment to the calcium silicate is 1:3 ~ 3:1; the water-based hybrid acrylic emulsion is RJ-630 water-based hybrid acrylic emulsion.

2. The inorganic silicon-modified water-based corrosion-preventing and -inhibiting paint containing a functional polysiloxane according to claim 1, characterized by, The amino-functionalized polysiloxane emulsion or aqueous dispersion is KF-8010.

3. The inorganic silicon-modified water-based corrosion-preventing and -inhibiting paint containing a functional polysiloxane according to claim 1, characterized by, The pigment filler is selected from at least one of titanium dioxide, iron oxide pigment, mica powder, talc, barium sulfate, and kaolin; the water-based additive is selected from at least one of wetting agent, dispersant, defoamer, leveling agent, thickening agent, film-forming aid, and pH adjuster.

4. A process for the preparation of the coating material according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: (1) The inorganic silicon-based corrosion inhibitor filler and the pigment filler are added to water, and are dispersed and ground at high speed in the presence of a wetting agent and a dispersant to a specified fineness to prepare a pigment slurry; (2) The water-based hybrid acrylic emulsion and the functional polysiloxane are added to the pigment slurry obtained in step (1) under stirring; (3) Other water-based additives and the remaining water are sequentially added, and are stirred uniformly, adjusted to a construction viscosity, and filtered to obtain the coating.

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