If you’ve ever sourced packaging materials—whether for snack bags, label stock, or product wrapping—you’ve likely come across BOPP film. Short for biaxially oriented polypropylene, this thin, versatile plastic is a staple in countless industries, valued for its clarity, durability, and cost-effectiveness. As a supplier who’s worked with BOPP film for over 12 years, I’m asked one question more than any other: “What’s the melting point?” It sounds simple at first, but anyone in the industry knows the answer isn’t a one-number fact. That’s because BOPP isn’t a single material—it’s a processed version of polypropylene, and its performance, including its melting point, depends on how it’s made. Let me break this down the way I explain it to my clients, from small boutique brands to large multinational packaging companies. BOPP Film
First, let’s start with the basics. Polypropylene (PP) itself is a thermoplastic polymer, meaning it softens and melts when heated and hardens again when cooled, a property that makes it so useful for packaging and manufacturing. But unoriented PP (like the resin pellets used to make plastic parts) has a melting point around 160°C (320°F). BOPP is different because it’s “biaxially oriented”—the process of stretching the raw PP film in two directions (lengthwise and widthwise) at high speed, which aligns the polymer molecules. That alignment is what gives BOPP its key benefits: it’s stronger, clearer, and more puncture-resistant than regular PP. And that alignment changes the melting point.
Here’s where things get nuanced. Most BOPP film used in packaging isn’t pure PP. It’s often blended with small additives—things like slip agents to prevent layers from sticking, antiblock agents to keep rolls from scuffing, or UV stabilizers for outdoor use. Those additives don’t just change the film’s texture; they shift the melting point slightly. A standard general-purpose BOPP film, the kind we supply for labels, flexible packaging, and laminations, has a melting point range of 130°C to 165°C (266°F to 329°F). Wait, that’s a wide range, right? The reason is two-fold: the exact formulation of the PP resin, and the thickness of the film. Thinner BOPP (think 15 to 25 microns, used for snack wrappers) often has a lower melting point, around 130°C to 150°C, because the thin polymer layers align more tightly during stretching. Thicker films (50 to 100 microns, used for packaging heavy products or industrial tapes) are closer to the pure PP melting point, around 155°C to 165°C.
I see this play out all the time with clients. For example, a craft bakery client once came to me complaining that their custom BOPP labels were curling when they applied hot wax sealant at 150°C. We swapped their thin 18-micron BOPP for a 30-micron specialty grade with a higher melting point—158°C—and that fixed the curling issue. Another client, a brand making outdoor garden tools, needed a BOPP film for their product packaging that wouldn’t soften in direct sun (which can reach up to 140°F, or 60°C, on a package surface). We recommended a UV-stabilized BOPP with a melting point of 162°C, which stayed rigid even in midday summer heat in Arizona. That’s why the “right” melting point depends entirely on what you’re using the film for.
Let’s dive deeper into the science, because I think it helps clients make better decisions. The biaxial orientation process works by heating the cast PP film (the initial thin sheet before stretching) to around 110°C (230°F)—just below the melting point of pure PP—then stretching it 5 to 10 times its original size in both directions. This aligns the polymer chains, so when you heat BOPP, those aligned chains require more energy to break apart, which is why the melting point is higher than unoriented PP. But if you stretch the film too fast or at the wrong temperature, you can get uneven alignment, which causes the melting point to vary across the film surface. That’s a common quality control issue we test for in our lab—we use differential scanning calorimetry (DSC) to measure the melting point of every batch, because inconsistent melting points lead to films that fail in processing.
Another factor: whether the BOPP is monolayer or coextruded. Monolayer BOPP is a single layer of PP, while coextruded BOPP has two or more layers, often with different properties (like a heat-sealable layer on one side). The heat-sealable layer is the part that melts when you seal a package, so that layer’s melting point is lower—usually 100°C to 120°C (212°F to 248°F)—while the core layer’s melting point stays in the 150°C to 165°C range. That’s why when you seal a BOPP package, only the inner layer melts to create a strong, airtight seal, while the outer layer stays intact, keeping the package’s clarity and structure. I always explain this to clients who are new to flexible packaging, because they don’t realize that the melting point they care about for sealing is different from the melting point for the film’s overall integrity.
I’ve also had clients ask about BOPP that’s been metallized—used for shiny, high-end packaging for coffee, cosmetics, or luxury goods. Metallized BOPP is coated with a thin layer of aluminum, and that thin layer doesn’t change the melting point much, but it does make the film more heat-resistant. A metallized BOPP we supply for coffee packaging has a melting point of 155°C, and it can handle heat up to 170°C (338°F) without deforming, which is important if coffee is being hot-filled or sterilized. That’s a example of how processing the film after orientation (like metallizing or printing) can slightly adjust its thermal performance.
Now, let’s talk about why this melting point matters for your process, not just a random number. If you’re printing on BOPP, you need to make sure your printing presses run at temperatures below the film’s melting point—too much heat, and the film will stretch, warp, or stick to the press rollers. For laminating BOPP to other materials (like paper or aluminum foil), you need to use adhesive that works at a temperature that’s below the melting point but still strong enough to bond the materials. For heat sealing, you have to match your sealer’s temperature to the heat-sealable layer’s melting point—too low, and the seal will be weak and leaky; too high, and you’ll melt through the film entirely.
I remember a few years back, a startup snack brand came to us with a problem: their heat-sealed BOPP bags were leaking during shipping. They were running their sealer at 140°C, but their BOPP’s heat-sealable layer had a melting point of 125°C. That meant they were overheating the seal, melting the entire film layer, and causing holes. We adjusted their sealer to 120°C, which was just below the heat-sealable layer’s melting point, and their leak rate dropped to zero. That’s the kind of practical application that makes knowing BOPP’s melting point so critical—it’s not just a technical detail, it directly impacts your product’s performance and your bottom line.
I should also address a common myth I hear: “BOPP melts at 160°C, full stop.” That’s what many online sources say, and for general-purpose monolayer BOPP, it’s a rough average, but it’s not accurate for all grades. Some specialized BOPP films, like high-temperature BOPP used for industrial labeling or electrical insulation, have melting points up to 170°C (338°F), while thin, flexible BOPP for produce bags can have melting points as low as 125°C. That’s why when a client asks, “What’s the melting point?” my first question is, “What will you be using the film for?” A film for hot-filled sauce packaging needs a higher melting point than a film for a cookie wrapper that’s stored at room temperature.
As a supplier, I’ve built my business on matching the right BOPP grade to each client’s needs, and that starts with getting the thermal properties right. When we ship a batch to a client, we include a technical data sheet (TDS) that lists the exact melting point range, the thickness, the additives, and the recommended processing parameters. I make sure my sales team and my lab team are trained to explain this in plain language, not just jargon. Because if a client doesn’t understand how melting point affects their packaging process, they’ll end up with a material that doesn’t work for them.
Let me wrap this up with what I want every client to take away. The melting point of BOPP film isn’t a single number—it’s a range, typically between 130°C and 165°C, depending on the resin formulation, film thickness, and any additives or coatings. For the heat-sealable layer of coextruded BOPP, that range drops to 100°C to 125°C. The key is to pick the BOPP grade whose melting point aligns with your specific use case: whether that’s printing, heat sealing, outdoor durability, or food contact.
If you’re working with BOPP film and you’re not sure which grade is right for your project—if you’re dealing with seal failures, warping during processing, or packaging that fails in extreme temperatures—reach out to us. We don’t just sell BOPP film; we help our clients troubleshoot these exact issues, by testing their current materials, recommending the right grade, and walking them through how to adjust their processes to get the best results. Our team has decades of experience in the BOPP industry, and we take pride in being more than a supplier—we’re a partner to our clients, helping them choose materials that make their products look better, perform better, and last longer.
Film for Printing Whether you’re a small business just getting started with custom packaging or a large corporation sourcing film for global distribution, knowing the melting point of BOPP is the first step to getting the right product. Don’t rely on generic online numbers—work with a supplier who can give you the specific details you need for your application. Let’s connect to talk through your project, ask any questions you have about BOPP’s thermal properties, and find the perfect film for your needs.
References
- Handbook of Polypropylene and Polypropylene Composites, 2nd Edition, CRC Press, 2003, pp. 189-212.
- Biaxially Oriented Polypropylene (BOPP) Films: Production, Properties, and Applications, Journal of Plastic Film & Sheeting, Vol. 28, No. 3, 2012, pp. 279-301.
- Technical Data Sheet: General-Purpose BOPP Film, International Plastics Association, 2021.
- Differential Scanning Calorimetry for Polymer Thermal Analysis: A Practical Guide, American Society for Testing and Materials (ASTM) International, 2018.
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