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(Designed for packers, cold-chain operators and retailers; shelf-life extension ≥ 14 days) 1. Background  • China’s post-harvest fruit loss: 15–25 %, mainly dehydration, browning and fungal decay.  • Conventional coatings (shellac or petroleum wax) are brittle, contain volatile organic compounds (VOCs) and face EU/US import restrictions.  • Carnauba wax (E903) is a natural, food-grade wax extracted from Brazilian palm leaves. High melting point (82–86 °C), excellent gloss, fully edible and globally compliant. 2. Technical Objective  Create a 8–12 µm semi-permeable edible film that:  • Reduces water-vapor transmission rate (WVTR) to 40–60 g m⁻² day⁻¹  • Maintains selective O₂/CO₂ exchange (internal O₂ 3–5 %, CO₂ 5–8 %)  • Extends marketable life of citrus, apples, mangoes, avocados, stone fruit by ≥ 14 days at 4–8 °C, 85–90 % RH. 3. Coating Formulation  (100 kg working solution; treats 10–12 t fruit) | Ingredient                             | Function                          | Mass (kg) | Regulatory Note               |---------------------------------------|----------------------------------|-----------|----------------------------------| Carnauba wax, refined         | Primary film former          | 4.0       | E903, FCC, GB 1886.84       | High-methoxyl pectin            | Thickener & anti-settling  | 0.3       | E440, GRAS                          | Tween-80 (Polysorbate 80)   | Emulsifier (HLB 15)          | 0.4       | E433, < 10 mg kg⁻¹ residue    | Potassium sorbate               | Antimould                          | 0.15     | E202, ≤ 200 mg kg⁻¹ in final fruit  | Ascorbic acid                       | Browning inhibitor              | 0.2       | E300, GRAS                          | Citric acid                             | pH adjuster / synergist      | 0.1       | E330, GRAS                          | De-ionised water                  | Solvent                              | 94.85   | —                                          Final solids 4.7 %; pH 3.9 ± 0.2; viscosity 25 °C: 40–60 cP. 4. Manufacturing Protocol  Lab (1 L) → Pilot (100 L) → Plant (10 t) Step 1: Melt carnauba wax at 90 °C under slow agitation.  Step 2: At 65 °C add Tween-80, shear 3 000 rpm for 5 min.  Step 3: Continuously shear at 10 000 rpm while adding aqueous phase (pectin, preservatives, acids, 65 °C) over 10 min.  Step 4: Pass twice through high-pressure homogeniser at 55 °C, 30 MPa.  Step 5: Filter through 100 µm mesh.  Step 6: Cool to 25 °C.  Final emulsion: off-white with bluish cast, mean droplet size 200–400 nm, zeta-potential −30 mV, stable ≥ 6 months at 5–25 °C. 5. Application Line (in-line or batch)  a. Pre-treat: Sort, brush-wash, 100 ppm chlorine rinse, spin-dry (< 1 % surface moisture).  b. Coating: Immerse 30 s or spray 2–3 bar, coverage 8–10 mL kg⁻¹ fruit.  c. Drain: 20 s on perforated belt.  d. Set: Warm air 45 °C, 60 s, then ambient 5 min.  e. Pack: Return to 4 °C cold-chain; maintain 85–90 % RH. 6. Performance Data (independent lab, ‘Valencia’ oranges, 20 °C)  Parameter | Control | Coated--------------------------|---------|---------Weight loss day-14 | 6.8 % | 2.3 %Firmness retention | 78 % | 93 %Decay incidence   | 12 % | 2 %Internal O₂            | 21 % | 4.1 %Internal CO₂         | 0.03 % | 6.2 %Surface gloss (GU 60°) | 4.2 | 8.9 7. Regulatory & Labelling  • Complies with EU 231/2012, US 21 CFR §184.1978, GB 2760.  • Declarable as “coating (carnauba wax)” or “surface-treated with food-grade wax”. 8. Cost & Sustainability  • Material cost: ~USD 0.22 per 10 kg fruit batch.  • Zero VOC, water-based, no microplastics; wax is RSPO-certified sustainable. 9. Troubleshooting Quick Guide  Observation → Cause → Fix  • Cracking film → high solids → dilute to 4 %.  • White bloom → cooling too slow → increase airflow 45 °C.  • Off-flavor → over-dose sorbate → verify 150 ppm max residue. 10. Scale-Up Contacts  Pilot tolling: 500 L batch available at Shanghai–Kunshan Food-Tech Park.  Full plant design: 2 t h⁻¹ line (dip + dryer + UV-C) quoted at USD 180 k. Ps.:The above information is for reference only. For detailed information, please consult the salesperson

In the industrial coating sector, epoxy resin is widely used due to its excellent adhesion, chemical resistance, and mechanical properties. However, its poor yellowing resistance limits its application in outdoor settings and scenarios where color requirements are high. On the other hand, acrylic emulsion is renowned for its superior weatherability and yellowing resistance. Combining these two materials can effectively address the yellowing issue of coatings while retaining the excellent properties of epoxy resin. This article presents a successful case of using this combination.   Case Background A well-known automotive manufacturing company, aiming to enhance the weatherability and yellowing resistance of its car body coatings while maintaining good mechanical properties and adhesion, decided to improve its existing epoxy resin coating system. The company's previous coating system exhibited significant yellowing after a period of outdoor use, affecting the appearance quality of the cars. Therefore, a coating solution that could effectively solve the yellowing problem was urgently needed.   Technical Solution In collaboration with material suppliers and research institutions, the company adopted a novel water-based acrylic epoxy resin emulsion as the main material for the coating. This emulsion was prepared by grafting modification of epoxy resin with specific nonionic surfactants and then using the modified surfactant in the subsequent fine emulsion polymerization, achieving an organic combination of acrylic emulsion and epoxy resin.   During the preparation process, the epoxy resin was first melted and reacted with the specific nonionic surfactant to form a nonionic surfactant containing epoxy structure. Subsequently, monomers such as styrene, methyl methacrylate, and butyl methacrylate were mixed with the surfactant and subjected to emulsion polymerization. By precisely controlling the reaction temperature, time, and raw material ratios, the stability of the polymerization process and the uniformity of the emulsion were ensured.   Application Results After applying this novel water-based acrylic epoxy resin emulsion to the car body coatings, a series of rigorous tests were conducted. The results showed a significant improvement in yellowing resistance. In outdoor exposure tests, the coating maintained a much lower yellowing index compared to traditional epoxy resin coatings, preserving its appearance quality even after prolonged UV exposure and temperature changes. Additionally, the mechanical properties and adhesion of the coating were not significantly affected and continued to meet the high standards required for automotive manufacturing.   Moreover, the coating system exhibited good chemical and water resistance, effectively withstanding various environmental factors and extending the service life of the car body. Through this innovative material combination and process improvement, the automotive manufacturing company successfully solved the yellowing problem of the coatings, enhancing the market competitiveness of its products. This case also provides valuable experience and reference for other companies in the same industry.   Conclusion The combination of acrylic emulsion and epoxy resin offers an effective solution to the yellowing resistance problem of coatings. By employing specific graft modification and emulsion polymerization processes, the advantages of both materials can be fully leveraged to produce high-performance coating materials. This innovative material combination and process improvement not only meets the strict requirements for coating properties in high-end industrial fields such as automotive manufacturing but also holds broad application prospects and promotional value.