In-mold coating technology is booming! Saying goodbye to traditional spraying, it paves a new path for the green upgrade of the film‑material industry.

Preface 

The membrane and plastics processing industries have long relied on conventional post‑spraying processes, but their… High VOCs Emissions, cumbersome processes, low efficiency, and high overall costs These pain points can no longer keep pace with the trends of green manufacturing and product premiumization. 2026 At the annual rubber and plastics exhibition, In-mold coating ( IMC/IMD-IMC )   Becoming a hot topic, this… \\ “ Molding +  Integrated Coating ”\\  The technology is transitioning from the laboratory to large-scale mass production, emerging as a key avenue for upgrading surface treatments of membrane materials and plastic components. 

This article reviews the definition, principles, advantages, processes, applications, industry developments, and common misconceptions of in-mold coating, helping you quickly master this cutting-edge technology and seize emerging opportunities in the industry. 

I. Basic Understanding: What is In-Mold Coating Technology? 

In-mold coating (also known as In-mold coating, in-mold painting, IMC ), is to Substrate Forming and Surface Coating An integrated process carried out simultaneously within the mold, primarily used for… Plastic parts, film‑plastic composite parts Surface decoration and protection, compared with traditional… “ Spray coating after molding. ”  There is an essential difference. 

1. Core Definition 

The plastic substrate is molded within the injection mold, after which it is injected into the cavity through a reserved gap. Liquid coatings (commonly two-component polyurethane) / Single-component PUR , acrylic system) , the coating is inside the mold Low-temperature, low-pressure leveling and heating / Moisture-cured , once the mold is opened, the painted finished product can be obtained, No secondary spraying, baking, or sanding required. 。

2. Core Positioning 

Replacing traditional post‑spraying, it addresses the surface of plastic and film‑molded parts. Decoration, protection, wear resistance, weather resistance According to demand, achieve One-piece molding, low VOC , stable quality, improved efficiency , suitable for applications such as automobiles, home appliances, and high-end laminated film components. 

3. Differences from Traditional Post-Spray Coating 

• Process: Traditional 5–6 Way (forming) → Deburring → Pre-processing → Spraying → Drying → Inspection) → In-mold coating 2–3 Integrated Road System (Injection molding → In-mold coating → Curing and demolding) 
• Environmental protection: Traditional VOCs High emissions and large solvent consumption. → In-mold coating VOC Emissions reduced by approximately 70%–85% (Not absolute 90% ), enclosed operations and a significant reduction in solvent usage 
• Quality: Traditional products are prone to color variation, sagging, pinholes, and scratches. → In-mold coating The coating is uniform, exhibits excellent consistency, and has few surface defects. 
• Costs: Traditional labor, equipment, facilities, and environmental remediation all entail high expenses. → In-mold coating After scaling up, the unit-level total cost decreases. 15%–25% (Not absolute 30% ) 

II. Core Principle: How Is Integrated Molding Achieved? 

The core of in-mold coating is Simultaneous substrate molding and surface coating are performed within a closed mold. , the key lies in Mold structure, coating formulation, and process parameter optimization , divide 4 Step: 

1. Preparation: Mold allowance 0.1–0.3mm Uniform spray gap , prepare the plastic substrate (or PET/BOPP Membrane pre-embedded components, conformable liquid coatings; 
2. Injection molding: The molten plastic is injected into the mold cavity, where its surface conforms to the cavity walls. 
3. Spraying: Close the mold to the preset gap, Low-pressure metered coating injection , the coating flows and levels within the gaps, covering the substrate surface; 
4. Curing: In-mold Low-temperature heating / Moisture-cured The coating forms a strong bond with the substrate, and upon cooling, the mold can be opened to obtain the finished product. 

Critical Control Point: Mold sealing performance, coating leveling, interfacial adhesion, curing temperature and time , directly determining the yield and stability of the finished product. 

III. Core Advantages: Why Are They Becoming the New Industry Trend? 

1. Stable quality, suitable for high-end applications. 

• Uniform coating: thickness is controllable within 0.1–0.3mm , minimal color variation, no particulates, and no sagging; 
• Strong adhesion: formed through in-mold curing Chemistry + Physical combination , wear-resistant, scratch-resistant, and not easy to peel off; 
• Diverse aesthetics: It can achieve effects such as high gloss, matte finish, metallic texture, and wood grain, with no need for post‑processing. 
• Functional enhancements: Antibacterial, antistatic, hydrolysis‑resistant, and flame‑retardant additives can be incorporated to suit medical and electronic applications. 

2. Improved efficiency and shortened production cycle 

• Streamlined process: eliminates transfer, secondary spraying, high-temperature baking, and sanding. Production process shortened 20%–30% ；
• Work-hour optimization: single-piece production + Painting cycle 150–300 seconds (Non-uniform ability 120 within seconds), reducing man-hours by 20%–30% ；
• Flexible manufacturing: eliminates the need for large, dedicated painting facilities, enables quick changeovers, and supports multi‑variety, small‑to‑medium batch production. 

3. Environmentally friendly and compliant with regulatory requirements. 

• Low pollution: Enclosed operations, VOC Emissions reduced 70%–85% , reduce pollutants at the source; 
• High recyclability: Production waste can 90% The above is recycled and reused. , compliant with REACH 、 RoHS Environmental standards; 
• Low hazard: Reduces the use of thinners and cleaning agents, thereby lowering occupational health risks. 

4. Reduce costs and boost efficiency to enhance overall competitiveness. 

• Cost optimization: reduce labor, coating equipment, environmental protection measures, and facility investment. Unit costs decrease with scale. 15%–25% ；
• Yield Improvement: The overall pass rate can reach 95%–97% (Traditional appointment 88%–92% ), reduced scrap and waste; 
• Controllable investment: No need to build a new large-scale spraying line; the equipment typically has a short payback period. 1.5–3 Year. 

IV. Classification of Mainstream Processes: Scenario-Based Selection 

1. Polyurethane ( PUR / Two-component PU ) In-mold spraying (mainstream) 

Moderate curing speed, strong adhesion, and excellent wear and corrosion resistance, Minor scratches can self-heal at a certain temperature. ; compatible Automotive interior and exterior trim, high-end appliance housings, decorative panels ; Mature technology and high cost-effectiveness make it suitable for medium- to large-scale mass production. 

2. Acrylic ( PMMA ) In-mold spraying 

High transparency, excellent gloss, UV-resistant and resistant to yellowing ; compatible Transparent plastic parts, electronic housings, high-end cosmetic packaging, and optical film laminates ; It boasts an excellent aesthetic and tactile quality, making it ideal for applications requiring high transparency and superior weather resistance. 

3. In-mold silicone coating 

Soft and skin-friendly, waterproof and moisture-proof, High and low temperature resistance ( -40℃~120℃ ), good elasticity, and excellent biocompatibility ; compatible Medical protective films, maternal and infant products, outdoor waterproof components, soft-touch parts ; Highly functional, with stringent safety and compliance requirements. 

V. Core Application Scenarios: Implementation Domains 

1. Automotive (core application area) 

• Exterior: Bumper, side skirts, wheel arches, small exterior trim panels ( 1.4m×1.2m Large sizes still use conventional spraying. /  Primarily in-mold lamination, IMC Gradual penetration); 
• Interior: center console, B Column trim panels, door panel trim pieces, and dashboard bezels are paired with decorative films to enhance their premium texture. 
• Case: Several domestic automakers in Non-appearance A Tier-level, small and medium-sized interior and exterior trim parts Apply in-mold coating on a batch basis. 

2. Membrane Materials and Packaging 

• High-end membrane‑molded composite components: PET/BOPP Membrane–plastic composite components, achieving antibacterial, antistatic, and high-gloss surface finishes; 
• Packaging: Cosmetic, pharmaceutical, and food-grade packaging shells / Membrane material , balancing sealing and protection with an upgraded aesthetic; 
• Value: Addresses the pain points of membrane materials—prone to scratches, oxidation, and poor adhesion—thereby enhancing product value. 

3. Home appliances 

• Housing: refrigerator side panels, washing machine front panels, and air conditioner housings—replacing traditional painting to achieve metallic and wood-grain finishes. 
• Panel: control panel, smart lock panel, and small appliance housing—wear-resistant, fingerprint‑proof, and easy to clean. 
• Value: Reduced VOC It reduces emissions, enhances aesthetic appeal, and improves durability, meeting the growing demand for greener home appliances. 

4. Healthcare and Electronics 

• Medical: Disposable protective film, tourniquet housing, small medical device components , antibacterial, hydrolysis-resistant, and sterile‑compatible; 
• Electronics: consumer electronics housings, insulating components, and structural parts—antistatic, flame-retardant, and ultra-thin—designed to meet the demands of precision‑critical applications. 

VI. Industry Breakthroughs: 2026 Latest developments 

1. Technological Breakthrough: Medium- and Large-Sized Components with Complex Structures Are Gradually Entering Mass Production 

Already achieved domestically Small and medium sizes ( ≤0.8m×0.6m ) stable mass production, 1.2m×1.0m Medium- and large-sized components have entered the pilot production phase, with gradual progress in addressing deformation control, mold sealing, and coating uniformity. A challenging issue, covering components such as automotive bumpers and appliance panels. 

2. Domestication Breakthrough: Breaking the Monopoly of Overseas Equipment and Materials 

Domestic equipment manufacturers such as Yizhimi and Haitian have launched… In-house developed injection molding machines and molds specialized for in-mold coating. ; Wanhua Chemical and domestic coating companies are developing Domestic PUR / Acrylic-specific coating , form “ Equipment +  Mold +  Materials ”  Domestic substitution solutions to reduce procurement costs. 

3. End-to-end industrial-chain collaboration: accelerating large-scale implementation. 

Automakers and home appliance companies are collaborating. Molds, materials, coatings, equipment Enterprises collaborate to establish joint laboratories, develop industry standards, optimize process parameters, and advance technologies from pilot production toward… Medium- to large-scale mass production Rapid implementation. 

VII. Common Practical Pitfalls: Must Avoid 4 a pit 

1. All membrane materials / Plastic can be used for everything. → Wrong. Need Good heat resistance, suitable surface tension, and compatible adhesion to coatings. , priority PET/BOPP 、 ABS 、PC/ABS ; ordinary PE 、 PP Because Low surface polarity and poor heat resistance , it is prone to insufficient adhesion and high-temperature deformation, requiring a specially formulated primer for modification. 
2. Once scaled up, costs will inevitably be lower than those of traditional methods. 30% → Wrong. High short-term investment in equipment and tooling , the comprehensive cost after scaling up Reduce 15%–25% , which requires a comprehensive cost analysis incorporating output, yield, and environmental protection expenses. 
3. The thicker the coating, the better the protective effect. → Wrong. 0.1–0.3mm For the optimal range , if too thick, it is prone to出现 Cracking, delamination, and uneven curing ; If it is too thin, it will lack sufficient wear resistance, weather resistance, and protective performance. 
4. No cleanroom is required; production can be carried out in a standard workshop. → Wrong. Minute dust and impurities can cause pitting, particles, and pinholes in the coating. , required Class 10,000 to Class 100,000 cleanroom environment , the yield can be increased to 95% The above; the yield in a standard workshop is prone to be lower than 85%。

Conclusion 

In-mold coating is Green upgrading and high-end product development in the plastics and film‑plastic composite industries. an important pathway, resolving traditional spraying in one go High pollution, low efficiency, unstable quality, and high costs Addressing key pain points while balancing environmental sustainability, efficiency, cost-effectiveness, and quality. 

2026 Year, along with Mature domestic production of equipment and materials. , the technology is gradually transitioning from pilot production to large-scale manufacturing, with application scenarios rapidly expanding from automotive and home appliances to healthcare, electronics, and high-end packaging. Mastering in-mold coating… Core principles, process selection, quality control, and key pitfalls to avoid , is the key for relevant enterprises to capitalize on industry-driven opportunities, achieve cost reduction and efficiency gains, and upgrade their product offerings. 

In the future, technology will move toward High-efficiency curing, low VOC Formulation, flexible manufacturing, and stable large‑size molding Through iterative strategic direction, we continue to empower sectors such as membrane materials, automotive, and home appliances, driving high-quality, sustainable industry development.