How much do you know about de-molding/re-molding processes?
The technology of plastic-free/replacement plastics mainly comes from the trend of 'using paper instead of plastic' and environmentally friendly packaging. Traditional paper packaging, to look good, be waterproof and oil-resistant, and be heat-sealable (like food wrappers), usually needs to be laminated with a layer of plastic film, such as PE coating, BOPP/PET lamination, etc. But this layer of film is difficult to separate, making the paper packaging hard to recycle.
The emergence of plastic-free/replacement plastics aims to solve issues like recyclability, biodegradability, and repulpability without sacrificing functionality. Its core value is that it can provide protective and decorative effects similar to traditional plastic lamination (like abrasion resistance, waterproofing, gloss/matte finish, special tactile feel), while completely avoiding the use of plastic film, significantly improving the eco-friendliness of printed materials. It's one of the key technologies for the printing and packaging industry to achieve a green transformation.
Currently, the four main industry routes for plastic-free/replacement plastics are: hot transfer release films, PLA polylactic acid films, cellulose coatings, and plastic-replacement oils.
These four routes differ in process principles, commercialization progress, recyclability levels, and applicable scenarios. Let's follow the 'slash youth' to understand them one by one ---
1. Hot Transfer Release Film
Also called plastic-free film, plastic-free transfer film, replacement plastic transfer film, de-BOPP/PET, release transfer film, plastic-free peel-off film, eco-friendly release film, etc.
Starting in Guangdong in 2020, some material manufacturers started researching this process and were the first to commercialize it in 2023/24. This process can directly use existing conventional laminating machines and glue, simply add film winding devices, and have already been promoted in the South China printing circle.
Process principle: The printing surface is laminated with a special heat transfer film. The backend process is hot-pressed, and the BOPP/PET carrier film is completely stripped off. Only an ultra-thin functional protective coating remains on the paper surface. The printed sheet is made of pure paper substrate, and the carrier film produced by peeling is separately recycled and disposed of.
PPWR Recyclability Rating: ⭐⭐⭐⭐
Disadvantages: Still produces waste plastic film
This process is an emerging technology in the printing and packaging field in recent years, lacking mature foreign sources. It is a new process independently iterated from the domestic packaging environmental protection sector.
2. PLA
PLA stands for Polylactic-Acid, and its raw materials are fermented from biomass starch sources such as corn, cassava, and sugarcane. It is a mature bio-based biodegradable film material industrialized in the printing and packaging plastic replacement sector. PLA particles are just raw materials; film factories process them physically by melting to produce finished films that printing factories can purchase. The process involves no chemical reactions and is a form of physical molding. Laminating machines do not require modification but require specialized glue.
Since 2021, the industry has gradually promoted it.
PLA film used in printing and packaging is divided into several mainstream processes: 1. BOPLA biaxially stretched polylactic acid film: Benchmarked against BOPP film, highly transparent, suitable for color printing and window films; 2. PLA+PBAT blended casting film: improves flexibility and low temperature resistance, mostly used for bag making and composite flexible packaging; 3. PLA laminated paper: paper + PLA composite, replacing PE laminated paper cups and cartons, representing a plastic-reducing solution rather than completely plastic-free.
PPWR classifies it as a paper-bioplastic composite structure, classified as recyclable ⭐⭐
Disadvantages: 1. Poor heat resistance, with a long-term maximum temperature of about 55°C; 2. High brittleness at low temperatures, prone to film cracking at folded positions; 3. Incorrect glue selection can cause film peeling; 4. Barrier defects: water vapor barrier is weaker than PP and PE films; 5. Significant fluctuations in raw material prices; 6. Only degradable in industrial composting environments, not in natural household environments, and not considered pure paper recyclable packaging.
3. Cellulose coating
Also known as nanocellulose, regenerated cellulose, or plastic-substituted cellulose coatings.
Cellulose coating is currently one of the mainstream plastic-free barrier solutions for paper-based packaging to replace PE coatings, BOPP laminations, and fluorine-containing oil-resistant coatings.
Between 2016 and 2019, universities such as South China University of Technology, Jiangnan University, and Nanjing Forestry University published numerous papers on nanocellulose barrier coatings, and a few new materials companies in Guangdong began initiating projects to develop modified cellulose composite plastic replacement coatings. At this stage, there were very few cases of printing and packaging factories landing in the field; most were just samples with no bulk orders.
After 2020, with the implementation of domestic plastic restriction orders, the difficulties in recycling PE coatings and BOPP lamination became prominent; Modified cellulose composite water-based plastic replacement coatings began entering small batches in printing, paper cups, and food packaging sectors. A few printing companies in the Pearl River Delta began trial orders of cellulose-coated plastic-free paper products, mainly supplying export foreign trade customers.
The EU's new regulations on PPWR and PFAS banning fluorine in 2026 will force export paper packaging to be single-material recyclable, and cellulose barrier coatings are rapidly adopting and becoming one of the mainstream alternatives for printing and packaging.
Looking back, cellulose has accompanied the printing industry as a raw material for papermaking for over a century, but achieving plastic replacement with functional barrier coatings is a relatively young technological route. Modified cellulose raw materials such as carboxymethyl cellulose and hydroxypropyl methylcellulose were industrially produced as early as the last century, and for a long time were only used as additives in papermaking coatings to improve paper printing performance, without being developed as a waterproof or oil-resistant barrier layer. Entering the 21st century, breakthroughs in scientific research of nano-cellulose materials have shown the industry hope for plant-based coatings to replace petroleum-based plastics.
Process principle: Using cellulose extracted from wood pulp and plant fibers (modified cellulose, nanocellulose) as core raw materials, blended into water-based coatings, coated on the surfaces of paper and cardboard to form a dense functional film, thereby endowing the paper with waterproof, oil-proof, oxygen-blocking, heat-sealing, and other protective properties similar to plastics. The coating itself contains no petroleum-based plastics.
PPWR Recyclability Rating: ⭐⭐⭐⭐⭐ Highest
Disadvantages: 1. High material cost; 2. Weak water vapor barrier in high-humidity environments: cellulose contains a large amount of hydroxyl groups, and its water vapor barrier performance in humid environments is far inferior to PE plastic coating; In high-humidity scenarios, hydrophobic modification or double-layer composite coatings are generally required; 3. Limited long-term water immersion resistance.
4. Plastic replacement oil
Also known as surface plastic replacement oil, resin replacement oil, water-based plastic replacement oil, water-based plastic replacement gloss oil, scratch-resistant oil, etc.
Starting in 2022, the industry gradually promoted it.
Process principle: This is an environmentally friendly coating mainly composed of water-based polyurethane resin, applied to paper-based packaging surfaces. It provides protective functions similar to plastic films (waterproof, oil-resistant, wear-resistant, etc.), while maintaining the recyclability and degradability of the substrate.
Core resin systems: 1. Waterborne polyurethane dispersions (PUD) --- the most mainstream; 2. Waterborne acrylic resins; 3. Polyurethane-acrylic hybrid/blended systems.
Technical Specifications: All parameters are not mandatory national standards and are for reference only
Film formation method: moisture evaporation + resin particle fusion + self-crosslinking curing, classified as "chemical film formation"; Film formation thickness: usually 3–8 μm; Solid content: 28–40%; pH value: 7–9; Wet coating amount: 4–12 g/㎡; Surface drying time: about 50 seconds; Gloss (60°): glossy type 75–85°, matte type 1–15°; viscosity (4 cups) 40–90 s / 25°C; abrasion resistance: over 800 cycles at 4 pounds; fold resistance: no powder shedding or delamination after more than 10 cycles at 360°; Scratch resistance: Can withstand 30~40 wipes with alcohol; Anti-stickiness: None; Cobb value: None; Kit level: None; WVTR value: None; OTR value: None.
PPWR Recyclability Rating: ⭐⭐⭐⭐⭐ Highest
Disadvantages: 1. High cost: unit price higher than traditional lamination, production requires adjustment of printing equipment parameters (such as drying temperature and speed), potentially increasing energy consumption and debugging time; 2. Performance limitations: not absolute barrier; its waterproofing and moisture resistance are "waterproof" rather than "waterproof," unable to achieve complete, long-term, high-strength barrier effects of plastic lamination. Not suitable for products requiring long-term soaking, extreme high humidity, or ultra-long shelf life; No edge protection; like all surface coatings, paper cutting edges are exposed, and liquid may seep through the edges; 3. Higher processing and application threshold: more precise process requirements, with certain demands on paper surface strength and water absorption, coating amount and drying degree must be precisely controlled to avoid affecting results; Printing factories need to learn and adapt to master the best process; Printing factories need to select the corresponding model based on the specific packaging contents (water-based, oil-based, pH), as improper selection can easily lead to functional failure; 4. Market and Awareness Challenges: Insufficient end-consumer awareness: The product's appearance may not be as "bright" as laminated film, and consumers may mistakenly think it is "low-end" or unaware of its environmental value. Performance misunderstandings: If misused as a fully waterproof material, packaging may fail and trigger customer complaints.
In short, you can think of it as "brushing" paper with an invisible layer of "liquid plastic film," giving the paper both protective properties similar to lamination and direct recyclability without removing the plastic film. Its core feature is using water as the dispersion medium, with extremely low VOC (volatile organic compounds) content, making it an alternative to traditional non-degradable plastic lamination processes.
Application scenarios:
1. Food Packaging Sector (Largest Application Market)
Paper lunch boxes/cups/bowls: such as takeout lunch boxes, instant noodle bowls, paper cups (cold/hot drink cups), paper plates, etc., with coatings that effectively resist oil, water, and leakage, and meet food contact safety standards.
Fast food packaging: burger paper, French fry bags, pastry boxes, etc., providing short-term oil and water resistance.
Food paper bags: such as bread bags, snack bags, etc.
2. Packaging of daily chemical products
Cosmetic color boxes: replace traditional plastic laminated packaging, enhancing environmental image while maintaining aesthetics and mild waterproofing.
Tissue/wet wipe packaging: Enhances the moisture resistance of packaging.
Detergent labels: used for bottle labels, water- and rub-resistant.
3. Packaging for electronic products and high-end gifts
3C products (such as mobile phones and headphone packaging boxes): offer a delicate touch and wear resistance, aligning with the brand's environmental protection philosophy.
Gift boxes/luxury packaging: replacing plastic lamination, achieving matte/glossy visual effects and being recyclable.
4. Surface protection of paper products
Book covers/albums: waterproof and stain-resistant, extending service life.
Labels/Posters: Such as wine labels and outdoor posters, which must withstand moisture environments.
Cardboard/Carrying Paper Bags: Enhances strength and water resistance.
5. Industrial and specialty paper
Moisture-proof paper for building materials: temporary waterproof protection.
Agricultural seedling paper: biodegradable and water-resistant.
Special label paper: such as oil drum labels, oil- and chemical-resistant.
6. Biodegradable tableware package
Combined with degradable materials such as PLA (polylactic acid), used in eco-friendly meals.
Overall, the deplasticization/plastic-replacing process is evolving along the path of "plastic reduction → plastic replacement → plastic-free." Heat transfer peel films and PLA belong to the "plastic reduction" phase solutions, while cellulose coatings and plastic-replacing oils point toward the ultimate direction of "plastic-free and recyclable."
Enterprises should select products comprehensively based on their target market (such as whether exporting to the EU), product functional requirements (waterproof rating, shelf life requirements), production line conditions, and cost budget.