If you need to ship vaccines, seafood or biotech samples, you might wonder how to keep them frozen without leaking ice or complicated regulations. A flexible dry ice pack wraps solid carbon dioxide (CO₂) in a moldable polymer sheet to deliver ultra cold cooling that stays dry and reusable. Unlike regular gel packs, these packs reach as low as –78.5 °C and can be reused 30 times. In 2025, global dry ice demand is growing 5 % annually while CO₂ supply rises only 0.5 %, causing price spikes. This guide explains what flexible dry ice packs are, how to choose and size them, safety rules, when to use alternatives and the latest innovations.
What makes a flexible dry ice pack different from gel packs or solid dry ice? Learn about polymer technology, temperature range and reusability.
How do you size and apply flexible dry ice packs for your shipment? Get weight ratios, thickness guidelines and practical tips for overnight, two day and three day transit.
What regulations and safety measures apply to flexible dry ice packs? Understand hazard labels, ventilation requirements and handling precautions.
When should you use flexible dry ice packs versus gel packs or phase change materials? Compare cooling methods, costs and sustainability.
What 2025 trends and innovations are reshaping flexible dry ice packs? Explore market growth, bio based CO₂, smart sensors and hybrid systems.
What Are Flexible Dry Ice Packs and How Do They Work?
Direct answer
Flexible dry ice packs are thin blankets filled with solid CO₂ or advanced phase change polymers that maintain ultra low temperatures while remaining bendable and reusable. They combine a super absorbent polymer core with perforated plastic and non woven textile layers. When soaked in warm water, the polymer cells swell to form a padded sheet weighing about 900 g. Once frozen, the water and CO₂ inside the cells turn into dry ice; the sheet stays flexible and conforms to irregular products. Because dry ice sublimates directly from solid to gas, there is no liquid residue, so packages stay clean.
Detailed explanation
Flexible dry ice packs differ fundamentally from conventional gel packs and solid dry ice. Solid dry ice is pure frozen CO₂ at –78.5 °C; it provides intense cooling but sublimates quickly and cannot be refrozen. Gel packs, often marketed as “dry ice packs,” use water based gel to hold temperatures around 0 °C and are reusable but cannot achieve ultra cold ranges. Flexible dry ice sheets bridge the gap: modern versions hold temperatures of –12 °C to –18 °C for up to 48 hours and can be reused over 30 cycles with less than 10 % capacity loss. The sheets remain pliable when frozen, allowing you to wrap them around odd shaped items such as vials or fish fillets. When the dry ice sublimates, it absorbs 571 kJ per kilogram of heat, maintaining deep freeze conditions without moisture.
Flexible dry ice technology relies on cross linked polyacrylate polymers and micro perforated plastic. A 4 ply sheet such as Techni Ice HDR uses two non woven textile layers encapsulating a special refrigerant, with two heavy duty plastic layers fused to the textile. The cross linked polymer can reach temperatures as low as –190 °C—more than twice as cold as regular dry ice. To activate, you immerse the sheet in warm water until air bubbles escape; the polymer swells to create multiple sealed cells. After freezing, the sheet becomes a flexible cold blanket that can be cut between the cells and reused.
Layered architecture and polymer technology
Anatomy of a flexible dry ice pack:
| Layer | Composition | Role | Practical significance |
| Outer plastic | Perforated polyethylene or polypropylene | Allows water to penetrate during hydration and contains the polymer | Ensures the sheet can be activated and remains leak proof |
| Inner textile | Non woven fabric | Encapsulates the polymer and provides flexibility | Enables bending around irregular items and enhances durability |
| Polymer core | Cross linked polyacrylate or other sodium polyacrylate copolymer | Absorbs water and converts to dry ice during freezing | Delivers ultra cold temperatures and reusability |
| CO₂ or PCM infusion | Solid CO₂ or phase change material within the polymer cells | Provides the cooling power; sublimates or changes phase | Maintains –78.5 °C to –12 °C without melting |
This structure gives flexible dry ice packs several advantages:
Moldability: Sheets can wrap around products, reducing dead space and improving temperature uniformity.
Lightweight activation: Dehydrated sheets weigh around 40 g; after hydration they weigh about 900 g, so shipping weight remains manageable.
No meltwater: When the dry ice sublimates, it turns into gas; there is no liquid to wet the package.
Rehydration and reuse: Cells can be rehydrated multiple times without losing capacity.
Comparison of cooling methods
| Attribute | Flexible dry ice pack | Gel pack | Phase change material (PCM) pack | Meaning for you |
| Temperature range | –78.5 °C to –20 °C | 0 °C to 5 °C | –20 °C to –70 °C (engineered set points) | Choose dry ice packs for ultra cold shipping; gel packs for refrigerated goods; PCMs for strict moderate ranges |
| Cooling duration | 24–72 h depending on thickness | 12–48 h | 24–72 h with proper conditioning | Match duration to your transit time; thicker dry ice sheets last longer |
| Reusability | Polymer casing can be rehydrated; CO₂ must be replenished | Fully reusable; refreeze after use | Reusable; PCMs can be conditioned repeatedly | Consider total cost and sustainability |
| Hazard status | Class 9 hazardous material; requires UN 1845 labeling and ventilation | Non hazardous; easy to handle | Typically non hazardous; some PCMs are food safe | Factor in regulatory compliance and handling effort |
| Residue | Sublimates to CO₂ gas; no liquid | Melts into water; risk of leaks | Usually no residue; PCMs absorb heat internally | Keep packaging dry and avoid soggy boxes |
| Typical use cases | Frozen pharmaceuticals, biologics and specialty seafood | Meal kits, fresh produce and 2–8 °C medications | Vaccines requiring strict 2–8 °C or –20 °C ranges | Pick based on temperature sensitivity and regulatory complexity |
How to Choose and Size Flexible Dry Ice Packs for Your Shipment?
Direct answer
Size your flexible dry ice packs by matching the weight of dry ice to your payload and choosing sheet thickness based on transit duration. A common guideline is a 1:1 ratio of dry ice weight to product weight for overnight deliveries, increasing to 1.5–2:1 for multi day shipments. Sheet thicknesses of 12 mm, 18 mm and 24 mm correspond to approximately 24 , 48 and 72 hour hold times respectively. Always pre chill your product and container to reduce the thermal load and place dry ice sheets above the payload so cold air can sink.
Expanded explanation
When sizing flexible dry ice packs, start by classifying your product’s temperature needs. Frozen biologics and seafood require temperatures below –20 °C, while fresh produce or meal kits need 2–8 °C refrigeration. For ultra cold shipments, flexible dry ice sheets deliver the necessary environment. The quantity of dry ice depends on payload weight and transit time. According to Tempk’s guideline, use half the payload weight in dry ice for shipments under 12 hours, equal weight for 24–48 hours and up to 1.5 times for 48–72 hours. For example, if you’re shipping a 10 lb biotech kit overnight, use about 5 lb of dry ice; for a 48 hour transit, use about 10 lb; for a 72 hour transit, use around 15 lb.
Sheet thickness also matters. A 12 mm sheet lasts roughly one day; an 18 mm sheet lasts two days; and a 24 mm sheet lasts three days. Thicker sheets contain more CO₂ and reduce sublimation rate. Combine multiple thin sheets when thicker sheets aren’t available. Always pre condition your container by chilling it and your product for at least 24 hours before packing. This reduces the heat load and slows sublimation. Minimize empty space in the container using insulation or padding to prevent warm air pockets. Ensure the container has vents or pressure relief channels to allow CO₂ gas to escape.
Sizing guidelines and scenarios
| Transit duration | Recommended sheet thickness | Dry ice weight per kilogram of product | Typical applications |
| < 12 hours | 12 mm sheet or half sheet | 0.5 kg dry ice per kg product | Overnight medical samples, short haul seafood |
| 24–48 hours | 18 mm sheet or two 12 mm layers | 1–1.5 kg dry ice per kg product | Two day meal kits, vaccines shipping internationally |
| 48–72 hours | 24 mm sheet or three 12 mm sheets | 2 kg dry ice per kg product | Three day shipments of mRNA vaccines, cell therapies |
Practical tips and suggestions
Hydrate correctly: Soak the sheet in warm water for about 15 minutes, gently scrunching it so all cells fill. Remove when it indents under light pressure; over hydration can make cells prone to puncture.
Pre freeze thoroughly: Freeze the hydrated sheet for at least 24 hours at –20 °C or colder. This ensures uniform dry ice formation and reduces early sublimation.
Position strategically: Place the sheet above the product so cold air sinks around it. Use additional sheets below for long transit times.
Cut to fit: Use the perforated cells to cut the sheet around irregular items; seal cut edges with tape to prevent gel loss.
Rotate inventory: Keep at least two sets of sheets so one can be freezing while the other is in use.
Real world case: A biotechnology company shipping 25 lb of cell culture kits across the U.S. used 30 lb of flexible dry ice sheets and pre chilled containers. The shipment maintained sub zero temperatures for 60 hours with only 5 % dry ice loss.
Safety, Handling and Regulatory Requirements
Direct answer
Flexible dry ice packs contain dry ice, which is regulated as a Class 9 hazardous material. Packages must display the proper shipping name “carbon dioxide, solid” or “dry ice,” the UN number 1845 and the net weight of dry ice. Ventilation is crucial: never seal dry ice in an airtight container; provide pressure relief vents so CO₂ gas can escape. Wear insulated gloves and eye protection when handling sheets.
Expanded explanation
Although flexible dry ice sheets simplify handling, they do not change the underlying hazards of dry ice. Dry ice sublimates into CO₂ gas, which can displace oxygen and cause suffocation in confined spaces. Always work in well ventilated areas and avoid breathing the gas. Airlines and couriers limit the amount of dry ice per package—typically 2.5 kg for passengers and up to 200 kg for commercial shipments. When shipping biological samples, triple packaging is mandatory: a watertight primary receptacle, a secondary container with absorbent material and a strong outer box. Flexible dry ice packs also require hazardous materials training for anyone preparing shipments.
Regulatory compliance checklist
| Requirement | Details | Why it matters |
| Proper shipping name & UN number | Label packages as “dry ice” or “carbon dioxide, solid” and include UN 1845 | Ensures compliance and avoids fines |
| Net weight declaration | Record the dry ice weight on the package (e.g., 5 kg) | Allows carriers to verify weight limits |
| Class 9 hazard label | Use a diamond shaped label at least 100 mm per side | Alerts handlers to potential hazards |
| Ventilation | Use vented packaging or pressure relief valves | Prevents pressure buildup and suffocation |
| Personal protective equipment (PPE) | Wear insulated gloves and eye protection when handling dry ice | Prevents frostbite and injury |
| Training & documentation | Ensure handlers are trained and include required paperwork | Maintains safety and legal compliance |
Safety tips for users
Use vented containers: Never seal dry ice sheets inside airtight plastic bags or jars.
Monitor CO₂ levels: Use CO₂ monitors in storage areas, especially inside vehicles or small warehouses.
Limit quantities on aircraft: Passengers may carry up to 2.5 kg of dry ice without documentation; commercial shipments can carry up to 200 kg.
Dispose responsibly: Allow leftover dry ice to sublimate outdoors or in a vented space; never flush it down the drain.
Train your team: Personnel should complete hazardous materials training and update procedures regularly.
When to Use Flexible Dry Ice Packs vs. Gel Packs or PCMs?
Direct answer
Use flexible dry ice packs for shipments requiring ultra cold temperatures (below –20 °C) or extended frozen conditions; use gel packs or PCMs when products need chilled or moderate temperatures with simpler handling. Flexible dry ice packs excel at keeping vaccines, mRNA therapies and frozen seafood at –78.5 °C to –20 °C for up to 72 hours. Gel packs maintain 0–5 °C for 12–48 hours and are non hazardous. PCMs hold narrow set points (2–8 °C or –20 °C) for 24–72 hours and are reusable.
Expanded explanation
Selecting the right refrigerant depends on temperature requirements, duration, regulatory complexity and cost. Gel packs are ideal for meal kits, produce and pharmaceuticals requiring 2–8 °C; they’re non toxic, reusable and easy to handle. However, they offer limited hold times and may leak water. Flexible dry ice packs deliver the lowest temperatures without moisture and mold to irregular shapes, but they are classified as hazardous materials and require labeling and training. PCMs offer a compromise by providing stable temperature bands (e.g., –20 °C or +5 °C) for 24–72 hours, but they generally cannot reach the –78.5 °C needed for deep frozen biologics. Hybrid systems combine PCMs and dry ice sheets; a PCM layer buffers the payload, while a dry ice sheet on top extends freezing by 40 %.
Advantages and disadvantages of each cooling method
Flexible dry ice packs: Ultra cold temperatures, conform to products, no water residue; require hazard labeling and ventilated packaging.
Gel packs: Reusable, non hazardous and cost effective; limited hold time and risk of leaks.
PCMs: Maintain specific temperature bands and are reusable; higher upfront cost and narrower applicability.
Water packs: Cheap and simple; suitable for very short chilled shipments but melt quickly and can leak【811187269995851†L91-L93】.
Hybrid solutions for mixed loads
Hybrid systems are increasingly common, especially for mixed shipments. For example, a meal kit company may use a PCM pack to keep vegetables at 2–8 °C and a flexible dry ice sheet to keep frozen meats below –20 °C. Hybrid configurations can reduce dry ice usage by up to 40 % and lower the risk of supercooling. They also simplify compliance for the non hazardous portion of the shipment. When designing a hybrid packout, place the PCM or gel pack closer to temperature sensitive items and the dry ice sheet above everything else; use partitions to separate zones.
2025 Trends and Innovations Shaping Flexible Dry Ice Packs
Trend overview
The flexible dry ice pack industry is undergoing rapid change as supply constraints, sustainability and digitalization drive innovation. Dry ice consumption is rising about 5 % per year, while CO₂ supply grows only 0.5 % per year, causing shortages and price volatility up to 300 %. The global dry ice market, valued at USD 1.54 billion in 2024, is projected to reach USD 2.73 billion by 2032 (7.4 % CAGR). Meanwhile, the cold chain packaging refrigerants market—including dry ice, gel packs and PCMs—is forecast to grow from USD 1.57 billion in 2024 to USD 2.92 billion by 2032 (8.14 % CAGR), with Europe holding a 31.85 % share. In personal therapy, the reusable ice pack market is expected to grow from USD 1.2 billion in 2024 to USD 2.14 billion by 2032, a 7.5 % annual rate.
Latest advances at a glance
Localized CO₂ sourcing: Producers are building regional CO₂ capture hubs and capturing emissions from bioethanol fermentation to supply dry ice. Bioethanol plants can supply 30–60 % of a country’s CO₂ needs.
Biodegradable polymers: Manufacturers are adopting compostable or recyclable materials for sheet casings, reducing waste and appealing to eco conscious customers.
Hybrid cooling systems: Shippers mix dry ice sheets with PCMs to extend freezing by 40 % and reduce dry ice consumption.
Vacuum insulation panels (VIPs): High performance insulation reduces sublimation loss from 8 % to 3 % per day, allowing lighter packages.
Smart monitoring: Flexible sheets are increasingly embedded with temperature, humidity and location sensors that transmit data for real time intervention.
AI and route optimization: Sophisticated software models evaluate variables such as route length, ambient temperature and container insulation to recommend the optimal mix of dry ice sheets, PCMs and container types.
Market insights
Supply shortages and sustainability pressures are pushing the industry toward alternative CO₂ sources and hybrid systems. Localized production hubs reduce transport losses and respond to regional demand. On site CO₂ capture at food processing plants and breweries reuses emissions and stabilizes supply. Bio based CO₂ from fermentation reduces reliance on fossil fuels and lowers the carbon footprint. However, geopolitical factors can threaten local supply: in the UK, a trade deal allowing cheap U.S. bioethanol imports jeopardizes domestic CO₂ producers, which supply 30–60 % of the nation’s CO₂. Shippers therefore diversify their refrigerants and invest in better insulation to mitigate supply risks.
Frequently Asked Questions
Q1: Are flexible dry ice packs reusable?
The polymer casing can be rehydrated and refrozen multiple times, but the dry ice itself sublimates, so you must replenish the CO₂ for each use. For true reusability without replenishing, consider gel or PCM packs.
Q2: How long do flexible dry ice packs stay cold?
A properly sized sheet maintains ultra cold temperatures for 24–72 hours. A 12 mm sheet lasts about one day, an 18 mm sheet two days and a 24 mm sheet up to three days.
Q3: How do I activate and hydrate a flexible dry ice pack?
Soak the sheet in warm water for roughly 15 minutes, gently scrunching until the cells fill and air bubbles escape. Once hydrated, freeze it for at least 24 hours before use.
Q4: Are flexible dry ice packs safe for food contact?
Yes. High quality sheets use food grade polymers sealed within plastic. They do not leak harmful substances and leave no liquid residue.
Q5: What are the main safety precautions when using flexible dry ice packs?
Wear insulated gloves and eye protection, ensure containers are vented, label packages with UN 1845 and record the net weight of dry ice. Let unused dry ice sublimate outdoors.
Summary and Recommendations
Key takeaways
Flexible dry ice packs combine ultra cold cooling with moldable, reusable polymer sheets, delivering temperatures down to –78.5 °C without water residue.
They suit frozen pharmaceuticals, biologics and seafood requiring 24–72 hour protection; size the sheet using a 0.5–2:1 dry ice to product weight ratio and choose 12–24 mm thickness based on duration.
Safety and compliance are essential: label shipments with “dry ice,” UN 1845 and net weight, provide ventilation and wear PPE.
Gel packs and PCMs provide moderate temperatures and reusability; use them when your cargo needs 2–8 °C or strict temperature bands.
2025 trends favor hybrid systems, localized CO₂ sourcing, biodegradable materials and smart sensors to mitigate supply shortages and environmental impact.
Actionable advice
Evaluate your product’s temperature tolerance and transit time. Use the sizing table to match sheet thickness and dry ice weight to your payload and adjust for seasonal conditions.
Invest in quality insulation. Vacuum panels or recyclable liners reduce sublimation and allow you to use thinner sheets.
Train and equip your team. Ensure everyone who packs or ships flexible dry ice packs completes hazardous materials training and uses proper PPE.
Explore hybrid solutions. Combine flexible dry ice sheets with PCMs or gel packs to extend hold time and reduce CO₂ usage.
Monitor market trends and innovations. Keep up with local CO₂ sourcing, biodegradable polymers and smart sensor integration to stay competitive and sustainable.
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About Tempk
Tempk is a cold chain packaging specialist dedicated to preserving product quality during transit. We design flexible dry ice packs, gel packs, PCMs and insulated containers that cater to temperature ranges from 0 °C down to –78.5 °C. Our R&D team innovates with biodegradable polymers, smart sensors and hybrid cooling solutions to reduce waste and improve performance. With global certifications and decades of experience, we support pharmaceutical, food and biotech clients by delivering customizable packaging solutions that balance cost, compliance and sustainability.
Call to Action: Ready to optimize your cold chain? Contact Tempk’s experts for personalized advice on flexible dry ice packs, sizing strategies and hybrid cooling systems. We’ll help you choose the right solution, comply with regulations and meet your sustainability goals.
