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GB/T 25263 · MIO云母氧化铁 · 单道100-150μm

Epoxy Mica Intermediate Coating Epoxy MIO Intermediate

Name: Epoxy Micaceous Iron Oxide Intermediate Coating KF-MIO500 | KeXin New Material
Brand: KeXin New Material
Availability: InStock

2K/Two-Component环氧聚酰胺/云母氧化铁厚浆型Intermediate Coat — MIO迷宫效应物理屏蔽

Epoxy Mica Intermediate Coating（Epoxy MIO Intermediate）Uses epoxy resin and polyamide curing agent as film-forming materials、超细锌粉（Dry Film含量≥70%）High-performance two-component anticorrosive primer with main anti-rust pigments。The coating provides active corrosion protection through the sacrificial anode cathodic protection mechanism of zinc powder on steel.——即使Paint Film局部破损，The surrounding zinc powder continues to provide electrochemical protection to the exposed steel.。CompliesHG/T 3668-2020《Epoxy Mica Intermediate Coating》2类Standard，配套Epoxy Mica Intermediate Coating和聚氨酯/Fluorocarbon Topcoat后System耐中性盐雾≥1000h，MeetsISO 12944 C4-C5高腐蚀Environment等级要求。广泛应用于跨海大桥、Offshore oil platforms、石化Storage Tank、输电铁塔、Wind turbine tower、Anti-corrosion primer for major projects such as large steel structure workshops.。

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≥100μm/道

单道干Film Thickness度

MIO屏蔽

迷宫效应

≥65%

Volume solids content

≥5MPa

Adhesion by pull-out method

GB/T25263

Product Execution Standards

Sa2.5

Substrate treatment grade

5~40°C

Construction ambient temperature

2K/Two-Component5:1

Mixing ratio

ISO12944

C4-C5 corrosion level

Dry film zinc powder content

1000h+

Salt spray resistance system

≥6MPa

Adhesion by pull-out method

≥60%

Volume solids content

HG/T3668

Product Execution Standards

Sa2.5

Substrate treatment grade

5~40°C

Construction ambient temperature

2K/Two-Component10:1

Mixing ratio

ISO12944

C4-C5 corrosion level

Product Overview

product概述

Product Overview: Who is it suitable for? What problem does it solve?

Epoxy Mica Intermediate Coating是为需要在C4-C5高腐蚀Environment中获得15Heavy-duty anticorrosive primer designed for steel structures requiring long-term protection of over one year。它解决的核心问题是：普通Rust-Proof漆在沿海、化工大气、高湿等恶劣Environment下3-5年即失效，而Epoxy Mica Intermediate Coating通过"Cathodic protection+屏蔽防护"双重机制，配套Intermediate Coat和Topcoat后可Provides15-25年的长效防护——大幅Reduces全寿命周期维护cost。

Product Definition

Epoxy Mica Intermediate Coating（Epoxy MIO Intermediate），Chinese standard number HG/T 3668-2020. It is a two-component (2K) room-temperature crosslinking anticorrosive primer using epoxy resin (bisphenol-A type, CAS 25068-38-6) and polyamide curing agent (CAS 68410-23-1) as the film-forming material, ultrafine spherical zinc powder (CAS 7440-66-6, particle size 3-8μm, dry film mass fraction ≥70%) as the anticorrosive pigment, and xylene/n-butanol as the solvent system.

Corrosion protection mechanism:High-content zinc powder particles in the coating form continuous conductive pathways between themselves and with the steel substrate. Since the standard electrode potential of zinc (-0.76V vs SHE) is lower than that of iron (-0.44V), zinc acts as the anode in corrosion microcells and preferentially undergoes oxidation (Zn → Zn²⁺ + 2e⁻). The released electrons flow through the conductive network to the steel surface, cathodically polarizing the steel below its immune potential—this is known as "sacrificial anode cathodic protection." Meanwhile, the corrosion products of zinc (ZnO, Zn(OH)₂, basic zinc carbonate, etc.) gradually fill the coating pores, forming a dense secondary barrier layer—the "corrosion product self-healing effect."

Key performance data:

The dry film zinc powder content is ≥70% (compliant with HG/T 3668-2020 Category 2).
Volume solids content ≥60% (ISO 3233:1998)
Pull-off adhesion ≥6 MPa (ISO 4624:2016, test doll diameter 20mm)
Single coating resistance to neutral salt spray (NSS) ≥400h (ISO 9227:2022, rust width at the crisscrossing ≤2mm)
The complete system (epoxy zinc-rich 80μm + epoxy micaceous iron oxide intermediate coat 150μm + polyurethane topcoat 80μm) has an NSS resistance of ≥1000h.
Mixed application period: 4-8 hours (23°C, main agent: curing agent = 10:1 w/w)

Applicable substrates and limitations:Applicable to carbon steel, low-alloy steel, and cast iron substrates blasted to Sa2.5 (ISO 8501-1:2007). Not recommended for direct application on galvanized steel (the passivation film on the zinc surface will block the conductive path—sweep blasting pretreatment or an epoxy primer transition layer is advised), stainless steel (the surface passivation film must be removed first), or aluminum alloy (risk of galvanic corrosion—the potential difference between zinc and aluminum is too large). Application temperature limits: standard type 5–40°C (below 5°C, the epoxy-amine crosslinking reaction rate is extremely low, resulting in incomplete coating curing).

Industry position and application:Epoxy Mica Intermediate Coatingis one of the most widely used primer types in global heavy-duty anticorrosive coating systems (ISO 12944-5:2019 systems A2.08/A3.08/A4.08, etc.), forming a classic triple-protection system with epoxy MIO intermediate coat and PU/fluorocarbon/polysiloxane topcoat. Typical applications include: Akashi Kaikyo Bridge Japan (opened 1998, 100-year design life), Hong Kong-Zhuhai-Macao Bridge (opened 2018, 500,000m² steel box girders), North Sea offshore oil platforms (NORSOK M-501 system certification), etc. According to Grand View Research, the global zinc-rich primer market was approximately USD 2.8 billion in 2023, with Asia-Pacific accounting for 48% share.

Features

productFeatures

Cathodic protection sacrificial anode principle

1. Cathodic protection (sacrificial anode) mechanism

CoatingDry Film含≥70%锌粉形成连续导电网络。锌的Standard电极电位（-0.76V）低于铁（-0.44V），腐蚀发生时锌优先氧化（Zn→Zn²⁺+2e⁻），Releasing electrons to cathodically polarize steel to its immune potential——即使Coating有3-5mm破损，The surrounding zinc powder can still provide continuous electrochemical protection for exposed steel.，This makes the anti-corrosion performance of epoxy micaceous iron oxide intermediate paint far superior to that of ordinary anti-rust primers relying solely on physical shielding.。

2. Superior corrosion resistance and durability

单CoatingNSS≥400h（HG/T 3668 2类），配套Epoxy Mica Intermediate Coating+聚氨酯Topcoat后SystemNSS≥1000h。ISO 12944-2的C5-M极高腐蚀Environment（海洋飞溅区）下Designed service life15-25年。日本明石海峡大桥1998年采用Epoxy Mica Intermediate CoatingSystem，至今25Years or moreCoating仍保持完好——实际Service life远超Design值。

Heavy-Duty Anti-Corrosion Coating System

3. Excellent compatibility

与Epoxy Mica Intermediate Coating（MIO屏蔽层）、聚氨酯Topcoat（Weather-resistant decoration层）、Fluorocarbon Topcoat（超Weather-Resistant≥25年）、Polysiloxane topcoat（高Weather-Resistant+高耐化学）均FeaturesExcellent的层间Adhesion（Pull-off method≥5MPa）。Epoxy Mica Intermediate Coating+Epoxy Mica Intermediate Coating+Topcoat是ISO 12944-5The most classic heavy-duty three-coat protection system in the series——PrimerProvidesCathodic protection，Intermediate CoatProvidesThickness和物理屏蔽，TopcoatProvidesWeather-Resistant和装饰。

4. Wide adaptability to construction

Supports airless spray (nozzle 0.43–0.53 mm, 15–25 MPa), air spray, and brush/roller application (for small-area touch-ups). Single-pass dry film thickness: 60–80 μm. Mixing ratio: 10:1 (w/w). Pot life: 4–8 h (23°C). Wide temperature range for application (5–40°C); low-temperature formulation can be applied down to –5°C. Continuous stirring is required during spraying to prevent zinc powder sedimentation—use of a pressure pot with a pneumatic agitator is recommended to ensure coating uniformity.

5. Shop Primer Solderability

Specialized formulation (dry film 15-25μm) can be used as a shop primer—after application in the steel structure prefabrication plant, the steel remains suitable for welding and cutting. Welding fumes comply with occupational exposure limits (GBZ 2.1-2019), and the pass rate of X-ray inspection of welds is not affected. Suitable for automated spray painting on steel structure production lines—parts can be handled and stacked within 3-5 minutes after spraying. Note: Only the specialized shop primer formulation is weldable—the standard type with a dry film thickness of 60-80μm is not suitable for welding.

6. Environmental Compliance · Global Standards

Complies with HG/T 3668-2020 (China) Standard Class 2, ISO 12944-5:2019 system numbers A2.08/A3.08/A4.08, NORSOK M-501:2022 (Norwegian Petroleum Industry) System 1, SSPC Paint 20 (USA) Zinc-rich Primer Type II (≥77% zinc powder). VOCs<420g/L（GB 30981-2020），可通过ROHS 2011/65/EU和REACH (EC) 1907/2006ComplianceTesting。product碳足迹约2.8kg CO₂e/kg（摇篮到大门，SimaPro 9.5计算）——低于Inorganic zinc-rich primer（3.5kg CO₂e/kg）。

Technical Specifications

技术Parameters

Physicochemical parameters

Product TypeTwo-component epoxy polyamide/zinc powder coating (2K EP/Zn)

Dry film zinc powder content≥70% (HG/T 3668-2020 Category 2)

Volume solids content60±3%（ISO 3233:1998）

Mass solids content85±3%（GB/T 1725-2007）

Density (after mixing)2.10-2.30 g/cm³（20°C）

Mixing ratio (by weight)Main agent: curing agent = 10:1

Mixed use period4-8h（23°C）/ 2h（35°C）

Recommended dry film thickness (DFT)60-80μm / channel

Theoretical coating rate0.17-0.22 kg/m²（75μm DFT）

VOC content<420 g/L（GB 30981-2020）

Packaging Specs30kg base agent + 3kg hardener kit

Drying and performance

Dry to touch time≤1h (23°C, GB/T 1728-2020 Method B)

Dry hard time≤24h (23°C, GB/T 1728-2020 Method A)

Fully cured7 days (23°C, Tg stable by DSC method)

Minimum recoating interval8h（23°C）

Maximum recoating interval7 days (23°C; sand removal is required if the expiration date is exceeded)

Adhesion by pull-out method≥6 MPa（ISO 4624:2016，dolly Ø20mm）

Cross-cut adhesion≤1 level (ISO 2409:2020, spacing 1mm)

Impact resistance≥50 kg·cm（GB/T 1732-2020）

Resistance to neutral salt spray (NSS)Single coating ≥400h / Complete system ≥1000h (ISO 9227:2022)

Continuous operating temperature-20°C ~ 150°C

Technical parameters based on
• March 2024, National Coatings Quality Inspection and Testing Center Test Report (No.: NTC-2024-0315-ZR)
· HG/T 3668-2020《Epoxy Mica Intermediate Coating》第2类指标
The data in this table are typical values under standard laboratory conditions (23±2°C, 50±5%RH). Actual values may vary slightly depending on the substrate condition, construction process, and environmental conditions. Please contact technical support to obtain the batch COA (Certificate of Appointment).

Application Process

ApplicationProcess

Surface preparation

Sandblast to Sa2.5 (ISO 8501-1:2007), roughness Rz 40-75μm. Manual rust removal ≥ St3. Grease must be removed with SSPC-SP1 solvent. Primer application (RH) must be completed within 4 hours after sandblasting.<50%可延至8h）。禁忌：雨天/雾天/SubstrateTemperature低于露点3°C时禁止Application。

Paint mixing

Stir the main agent for 3-5 minutes until the zinc powder is completely and evenly dispersed. Add the curing agent at a ratio of 10:1 (w/w) and continue stirring for 3-5 minutes. Let it stand for 15-30 minutes (23°C) to mature. Continuously stir during application to prevent zinc powder from settling—a pneumatic mixer is recommended. The mixed usable period is 4-8 hours (23°C). Do not dilute and use materials that have gelled beyond this period.

Primer application

Airless spraying (recommended): Nozzle 0.43-0.53mm/0.017-0.021", pressure 15-25MPa. Air spraying: Nozzle 1.5-2.0mm, pressure 0.3-0.5MPa. Brush/roller coating is only suitable for small-area pre-coating and repair. Single-coat DFT 60-80μm. Pre-coat welds, free edges, etc.

Drying and recoating

Surface dry ≤ 1h (23°C), hard dry ≤ 24h. Minimum recoating interval 8h (23°C). Maximum recoating interval 7d—exceeding this interval requires sandblasting (low pressure 0.2-0.3MPa, non-metallic abrasive) to remove surface zinc salts (basic zinc carbonate). Matching: Epoxy micaceous iron oxide intermediate coat 100-150μm → Polyurethane/fluorocarbon topcoat 50-80μm × 2.

Inspection and Acceptance

DFT measurement (ISO 2808:2019, SSPC-PA2): 80% of measuring points ≥ specified value, no measuring points<80%规定值。AdhesionTesting（ISO 4624Pull-off method或ISO 2409Cross-cut test）。针孔Testing（湿海绵法，67.5V/90V）。Appearance检查：无流挂/漏涂/起泡/缩孔/锌粉不均匀。

Applications

应用Field/Area

Cross-sea/cross-river bridges

Steel box girder, bridge tower, arch rib

Offshore oil platforms

jacket, deck, living quarters

outer wall of petrochemical storage tank

Crude oil/refined oil/chemical storage tanks

Transmission towers/pipe towers

High-voltage/Ultra-high-voltage transmission line steel structure

Large steel structure factory building

Industrial plants and sports stadiums

Port machinery

Quay cranes, gantry cranes, ship unloaders

Wind turbine tower

Onshore/Offshore wind turbine towers

Naval Architecture and Ocean Engineering

Hull sections, ballast tanks, decks

Pipeline external corrosion protection

Oil and gas/water long-distance pipelines

Mining/Construction Machinery

Excavators, crushers, conveying equipment

Chemical/Refining Plant

Steel structure of reaction vessel, heat exchanger, and pipe gallery

Water treatment/water conservancy facilities

Wastewater treatment plant, sluice gate, trash rack

FAQ

常见问题

The anti-corrosion of epoxy micaceous iron oxide intermediate paint is based on the principle of electrochemical cathodic protection：Coating中高含量（≥70%）的锌粉颗粒之间形成导电通路，且与钢材基体导通。由于锌的Standard电极电位（-0.76V）比铁（-0.44V）更负，腐蚀发生时锌优先氧化：Zn→Zn²⁺+2e⁻。Released electrons flow toward the steel surface through the conductive network，使其阴极极化——电位降至-0.85V（vs Cu/CuSO₄）以下即可实现有效保护。如果锌粉含量不足（<60%），锌粉颗粒被环氧树脂绝缘包裹无法形成连续导电通路——Cathodic protection失效——Coating仅剩物理屏蔽功能，Anticorrosive寿命大幅缩短。这就是HG/T 3668Standard严格要求锌粉含量的原因：第1类≥80%（高Anticorrosive），第2类≥70%（Standard重Anticorrosive），第3类≥60%（一般Anticorrosive）。

It cannot be used alone.Tiga Sebab：(1)Epoxy Mica Intermediate Coating单层暴露在酸性（酸雨pH<5.6）或碱性（Concrete渗出碱液）Environment中，锌粉会被Quick化学消耗（反应速率较中性Environment快3-10倍），丧失Cathodic protection能力。Epoxy Mica Intermediate Coating（MIO片状填料层叠排列形成"迷宫效应"）Provides物理屏蔽层——保护锌粉不过早消耗。(2)环氧树脂含芳香醚键——紫外光（290-400nm）照射下3-6个月即开始光氧化降解——粉化/变色/失光。聚氨酯/Fluorocarbon Topcoat（含UV吸收剂和HALS光稳定剂）ProvidesWeather-Resistant保护。(3)配套System总DFT更厚（≥280μm）——Anticorrosive等级更高。ISO 12944-5推荐的重Anticorrosive配套：Epoxy Mica Intermediate Coating60-80μm + Epoxy Mica Intermediate Coating100-150μm + 聚氨酯Topcoat50-80μm×2。

According to HG/T 3668-2020, three types of zinc content are selected: Type 1 (≥80%) — suitable for C5/CX extremely corrosive environments (offshore splash zones, tidal zones, chemical plant acid mist areas) or major projects with a design life >25 years. It offers the highest cathodic protection efficiency, but excessive zinc powder increases internal stress and reduces flexibility (flexibility ≥3mm vs. Type 2's ≥2mm), and has the highest unit price. Type 2 (≥70%) — a general heavy-duty anti-corrosion primer suitable for C4-C5 environments (coastal industrial areas, sea-crossing bridges, petrochemical storage tanks), offering the best cost-performance ratio — an optimal balance between anti-corrosion performance and mechanical properties. Recommended for most industrial projects. Type 3 (≥60%) — suitable for C3-C4 environments (urban atmosphere, ordinary industrial plants) with general anti-corrosion requirements. Can be selected if the budget is limited and the environmental corrosion level is low. Selection suggestion: When in doubt, choose Type 2 (70%) — the safest universal option.

Zinc powder has a high density (7.14 g/cm³) and tends to settle easily in low-viscosity epoxy resin solutions. Solutions: (1) After opening the container, thoroughly stir with an electric/pneumatic stirrer for ≥5 minutes—completely lift the zinc powder from the bottom until no sediment remains. (2) After adding the hardener, continue stirring for 3-5 minutes until the mixture has a uniform color. (3) Maintain continuous low-speed stirring throughout the application process—a pressure tank with a pneumatic stirrer (rotation speed 30-60 rpm) is recommended to prevent zinc powder from re-settling during spraying, which could cause inconsistent zinc content between the initial and final spray. (4) Paint that has settled and hardened into lumps—do not forcibly stir for use (the zinc powder has separated from the resin and may form lumps, leading to pinholes, uneven zinc distribution, and reduced adhesion after spraying). Paint that has exceeded its mixed pot life and shows gelation—must be discarded. It is recommended to prepare the paint as needed (estimate usage within 2 hours), in small, multiple batches.

Epoxy Mica Intermediate CoatingWhen exposed to air, surface zinc powder reacts with CO₂ and H₂O to form basic zinc carbonate ("white rust"). After 7 days (23°C, 50%RH), the following treatment is required: (1) Visual inspection — white powdery zinc salts must be removed by sweep blasting using low pressure (0.2-0.3MPa) non-metallic abrasive (garnet/alumina) to remove the zinc salt layer and create 20-30μm roughness. (2) For coatings within 6 months without visible zinc salts — light sanding (180-240 grit hand sanding) is sufficient. (3) If the coating shows extensive chalking/rusting/peeling — complete blast removal and reapplication is required. Prevention: Complete intermediate coat application within the minimum recoat interval (8-24h) when the primer surface still has active amine groups (incompletely crosslinked), achieving optimal intercoat adhesion without sanding.

The key difference lies in the film-forming material.Epoxy zinc-rich — organic epoxy resin + polyamide curing agent; inorganic zinc-rich — inorganic ethyl silicate/lithium silicate hydrolysis condensation. Selection comparison: (1) Anti-corrosion performance: Inorganic zinc-rich primer (zinc content ≥85%) offers higher cathodic protection efficiency, certified under NORSOK M-501 and SSPC Paint 20 Type I (inorganic) — Type II (organic). Both can achieve equivalent anti-corrosion grades, but inorganic is slightly superior. (2) Application tolerance: Epoxy zinc-rich >> inorganic zinc-rich. Epoxy can be applied at 5–40°C/RH<85%宽条件Application；无机对RH要求苛刻——RH需50-90%（硅酸乙酯水解需要水分），低温（<5°C）和低湿（<40%）均无法正常Curing——Application窗口窄。(3)层间Adhesion：环氧富锌+Epoxy Mica Intermediate Coating的层间结合力（>5 MPa) is superior to inorganic zinc-rich + epoxy intermediate paint (possibly due to the porous nature of the inorganic coating increasing the contact area, but also potentially leading to insufficient adhesion due to surface chalking—requiring sweep blasting). (4) Cost: Epoxy zinc-rich is approximately 0.7–0.8 times the cost of inorganic zinc-rich. Selection recommendations: For conventional heavy-duty anti-corrosion projects, choose epoxy zinc-rich (easy application + high cost-effectiveness); for extreme marine environments (splash zone/tidal zone) or top-tier projects with a design life of ≥30 years—choose inorganic zinc-rich + sealer + epoxy intermediate coat + polysiloxane topcoat.

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