What Are the Material Differences Between Microwaveable Bowls and Refrigerator Bowls?
author: Iris
2025-12-08
I. Basic Definitions and Material Classification
1.1 Definition and Materials of Disposable Plastic Microwave Bowls
Disposable plastic microwave bowls are single-use plastic containers specifically designed for microwave heating. According to the latest GB/T 18006.1-2025 "General Technical Requirements for Disposable Plastic Tableware," these products are explicitly included in the category of disposable tableware and are applicable to products made from food-grade resins and other thermoplastic materials through thermoforming processes, including lunch boxes, plates, bowls, dishes, and cups.
From a material classification perspective, disposable plastic microwave bowls mainly use the following types of plastics:
From a material classification perspective, disposable plastic microwave bowls mainly use the following types of plastics:
Polypropylene (PP) is the most common choice, and most takeout and catering industry lunch boxes on the market use PP5 material. This material has the characteristics of high-temperature resistance, non-toxicity, microwave heating compatibility, and resistance to deformation. PP material lunch boxes usually have a temperature resistance range of -20℃ to 120℃, making them particularly suitable for holding hot meals such as fried rice and noodle soup.
Polystyrene (PS) is also a common material for plastic serving bowls with lids. The temperature resistance range of the PS material is relatively low, generally between 70-90℃, so it is more suitable for short-term, low-temperature microwave heating.
Polyethylene terephthalate (PET), although highly transparent, has poor heat resistance and can generally only withstand temperatures of 60-70℃, so its application in plastic microwave bowls is relatively limited.
Polystyrene (PS) is also a common material for plastic serving bowls with lids. The temperature resistance range of the PS material is relatively low, generally between 70-90℃, so it is more suitable for short-term, low-temperature microwave heating.
Polyethylene terephthalate (PET), although highly transparent, has poor heat resistance and can generally only withstand temperatures of 60-70℃, so its application in plastic microwave bowls is relatively limited.
1.2 Definition and Materials of Refrigerator Storage Plastic Bowls
Refrigerator storage plastic bowls are plastic containers specifically used for refrigerating and storing food, including both reusable food storage containers and disposable refrigerator containers. These products are explicitly excluded from the category of disposable tableware in the latest national standards. They are primarily used for food preservation, display, storage, and packaging purposes, such as fresh food trays, yogurt cups, and jelly cups.
The main materials used for refrigerated plastic bowls include:
The main materials used for refrigerated plastic bowls include:
Polyethylene (PE) is the most commonly used material for refrigerated plastic bowls. Based on density, it can be divided into high-density polyethylene (HDPE) and low-density polyethylene (LDPE). HDPE has high hardness and chemical resistance, with a temperature range of -50℃ to 80℃, and can be used for frozen food packaging. LDPE is softer and more transparent, with better low-temperature resistance, able to withstand extremely low temperatures of -70℃.
Polyethylene terephthalate (PET) is also widely used in refrigerated plastic bowls. PET material has high transparency and strong cold resistance, and is often used to make cold drink cups and fruit containers. Its excellent transparency makes it particularly suitable for packaging applications where the contents need to be displayed.
Polyethylene terephthalate (PET) is also widely used in refrigerated plastic bowls. PET material has high transparency and strong cold resistance, and is often used to make cold drink cups and fruit containers. Its excellent transparency makes it particularly suitable for packaging applications where the contents need to be displayed.
1.3 Relevant Standards and Specifications
Both types of products must comply with strict national standards. GB 4806.7-2023 "National Food Safety Standard for Plastic Materials and Products for Food Contact" is the latest mandatory standard. This standard integrates the original GB 4806.6-2016 and GB 4806.7-2016 standards and adds requirements for starch-based plastic materials and products.
The basic requirements for materials in the standard include:
The basic requirements for materials in the standard include:
- Raw materials must comply with food safety standards and not contain substances harmful to human health.
- The use of additives must comply with GB 9685-2016 "Standard for the Use of Additives in Food Contact Materials and Products".
- The use of recycled materials is explicitly prohibited; raw materials must be food-grade plastics (such as PP, PE, PET, etc.).
Disposable plastic microwave bowls must also meet the specific requirements in GB/T 18006.1-2025 regarding hot water resistance, hot oil resistance, and microwave oven temperature resistance. However, refrigerated plastic bowls need to comply with relevant industry standards for food storage containers, such as T/ZZB 1283—2019 "Environmentally Friendly Plastic Food Storage Containers," which strictly limits the chemical indicators of main materials such as PP and AS plastics, and EPDM sealing materials.
II. In-depth Analysis of Material Composition
From the comparison of material composition, it can be seen that there are significant differences in the selection of basic resins for plastic bowls with different uses:
| Comparison Item | Disposable Microwave Plastic Bowl | Refrigerated Plastic Bowl |
| Main Resin Type | Mainly polypropylene (PP), supplemented by polystyrene (PS) | Polyethylene (PE), polyethylene terephthalate (PET) |
| Density Range | PP: 0.90-0.91g/cm³ PS: 1.04-1.06g/cm³ | HDPE: 0.941-0.965g/cm³ LDPE: 0.91-0.94g/cm³ PET: 1.38g/cm³ |
| Main Additives | Antioxidants, nucleating agents, heat stabilizers, antistatic agents, etc. | Antioxidants, slip agents, anti-fogging agents, etc. |
| Additives Requirements | Must be high-temperature resistant, stable above 120℃ | Must be low-temperature resistant, stable below -20℃Must be low-temperature resistant, stable below -20℃ |
III. Performance Characteristics Comparison Analysis
3.1 Temperature Resistance Range Comparison
Temperature resistance is one of the most important characteristics that distinguishes disposable black plastic bowls from refrigerated plastic bowls. The two products have significant differences in temperature resistance range, which directly determines their usage scenarios.
Temperature resistance characteristics of disposable microwave plastic bowls:
Temperature resistance characteristics of disposable microwave plastic bowls:
- Polypropylene (PP) material: Has the widest temperature resistance range, able to withstand temperature changes from -20℃ to 120℃, and some modified PP can withstand high temperatures of 130-140℃. The melting point of PP is approximately 167℃, and the continuous use temperature can reach 100-120℃, making it resistant to microwave heating and boiling water. Polystyrene (PS) material: Has a relatively low temperature resistance range, generally between 70-90℃. Therefore, it is more suitable for short-term, low-temperature microwave heating and not suitable for prolonged high-temperature heating.
- Polyethylene terephthalate (PET) material: Has the worst heat resistance, only able to withstand temperatures of 60-70℃, so its application in microwave plastic bowls is very limited.
- According to the national standard GB/T 18006.1-2025, disposable tableware is divided into two categories based on temperature resistance: temperature-resistant (≥100℃) and non-temperature-resistant (<100℃). Microwave plastic bowls must belong to the temperature-resistant category and be able to withstand conventional microwave heating temperatures.
- Temperature resistance characteristics of refrigerated plastic bowls:
- High-density polyethylene (HDPE): The temperature resistance range is between -50℃ and 80℃, and the long-term use temperature should not exceed 70℃. HDPE has excellent low-temperature resistance and can maintain good toughness at -40℃.
- Low-density polyethylene (LDPE): Has even more outstanding low-temperature resistance, able to withstand a temperature range of -70℃ to 80℃, and some special formulations of LDPE can even withstand extremely low temperatures of -100℃.
- Polyethylene terephthalate (PET): Although it has poor heat resistance, it has good low-temperature resistance, making it particularly suitable for refrigeration and freezing applications.
- From the comparison of temperature resistance ranges, it can be seen that the design focus of disposable microwave plastic bowls is on high-temperature resistance, while the design focus of refrigerated plastic bowls is on low-temperature resistance. This difference reflects the distinctly different usage requirements of the two types of products.
3.2 Comparison of Mechanical Properties
Mechanical properties include various aspects such as hardness, flexibility, strength, and impact resistance of the material. These properties directly affect the user experience and durability of the product.
Mechanical properties of disposable microwave plastic bowls:
Mechanical properties of disposable microwave plastic bowls:
- Polypropylene (PP) material: Has high toughness and excellent impact resistance. PP plastic bowls are strong and have good tensile and bending resistance. Even with collisions and compression during daily use, they are not easily brittle or damaged, resulting in high durability. The elastic modulus of PP material is approximately 1.2-1.6 GPa, exhibiting good rigidity and dimensional stability.
- Polystyrene (PS) material: Characterized by high rigidity and brittleness. PS plastic containers have good stiffness and are not easily deformed, maintaining a good shape, but they have poor impact resistance and may crack or even break with slight impact, especially in low-temperature environments where the brittleness becomes more pronounced.
Mechanical properties of refrigerated plastic bowls:
- High-density polyethylene (HDPE): High rigidity, high hardness, high mechanical strength, and excellent chemical resistance. The tensile strength of HDPE is generally between 20-35 MPa, exhibiting good rigidity and compressive strength.
- Low-density polyethylene (LDPE): Excellent flexibility, strong impact resistance, and outstanding low-temperature performance and processing fluidity. The elongation at break of LDPE can reach 400-600%, showing excellent flexibility.
- Polyethylene terephthalate (PET): High mechanical strength, with tensile strength 3-5 times that of PE, exhibiting excellent rigidity and toughness. The tensile strength of PET can reach 50-70 MPa, making it one of the strongest types among all thermoplastics.
From the comparison of mechanical properties, it can be seen that:
- PP material has excellent toughness while maintaining good rigidity, making it particularly suitable for applications requiring a certain degree of flexibility.
- HDPE material has the strongest rigidity, suitable for containers that need to maintain a stable shape.
- LDPE material has the best flexibility, suitable for applications requiring bending or deformation.
- PET material has the highest strength, but is relatively brittle, requiring special attention in design.
3.3 Comparison of Optical Properties
Optical properties mainly refer to the transparency, gloss, and other appearance characteristics of the material, which have a significant impact on the visual effect and user experience of the product.
Optical properties of disposable microwave plastic bowls:
Optical properties of disposable microwave plastic bowls:
- Polypropylene (PP) material: Relatively poor transparency, with a light transmittance of about 85%, and the container is slightly milky white and translucent, unable to clearly display food details like other materials. However, the transparency of PP can be significantly improved by adding nucleating agents and other modification methods. Polystyrene (PS) material: Excellent transparency, with a light transmittance of over 90%, approaching the texture of glass, clearly displaying the color and shape of the food inside the container, resulting in a good visual effect.
- Polyethylene terephthalate (PET): Possesses excellent transparency and gloss, with a light transmittance of over 90%, clearly displaying the state and color of the contents.
Optical properties of refrigerated plastic bowls:
- High-density polyethylene (HDPE): Usually opaque or translucent, with poor transparency, which is related to its high crystallinity.
- Low-density polyethylene (LDPE): Has good transparency and a certain degree of gloss, suitable for packaging that needs to display the contents.
- Polyethylene terephthalate (PET): Has extremely high transparency and is one of the best materials for transparency in refrigerated packaging, especially suitable for applications that require a clear view of the contents.
From the comparison of optical properties, it can be seen that PS and PET materials have a significant advantage in transparency, making them particularly suitable for packaging applications that require displaying the contents. Although PP material has relatively poor transparency, this defect can be improved to some extent through technological improvements.
IV. Safety Assessment
4.1 Chemical Migration Risk Analysis
Chemical migration refers to the transfer of chemical substances from plastic to the food it comes into contact with, which is a core indicator for assessing the safety of plastic food containers. Two types of black plastic bowls with different uses show significant differences in chemical migration risk.
Chemical migration risk of disposable plastic microwave bowls:
Chemical migration risk of disposable plastic microwave bowls:
Studies show that microwave heating significantly accelerates the migration of chemical substances. According to a 2023 report by the European Food Safety Authority (EFSA), when plastic containers are heated in a microwave oven, the amount of microplastics and chemical additives (such as bisphenol A and phthalates) released increases by 2-5 times compared to room temperature.
Specific migration risks include:
Specific migration risks include:
- Bisphenol A (BPA) migration: Although PP material itself does not contain BPA, some substandard products may contain BPA. Studies show that PC material can release up to 0.05 μg/L of BPA when heated to 100°C, exceeding the EU safety threshold of 0.01 μg/L.
- Plasticizer migration: When ordinary polyethylene plastic boxes are heated in a microwave oven to above 60°C, the amount of plasticizer migration increases rapidly. After 3 minutes of heating, billions of plasticizer molecules can be released into each liter of food, far exceeding the national standard limit by 2-3 times.
- Oligomer migration: Even PP5 material that meets safety standards may still lead to the migration and release of oligomers at high temperatures.
It is particularly important to note that high-oil and high-sugar foods significantly accelerate the migration of chemical substances. Experiments show that after microwave heating of food containing chili oil, the pigments and oils in the food container dissolve into each other, and the amount of chemical substances leached out is 4 times higher than at room temperature. Tests by the Shanghai Center for Disease Control and Prevention found that after microwave heating of plastic food containers containing hot and sour soup (containing vinegar), the amount of bisphenol A migration exceeded the national standard by 8.3 times (acidic environment accelerates degradation).
Chemical migration risk of refrigerated plastic bowls:
- Although refrigerated plastic bowls are used at lower temperatures, there is still a certain risk of chemical migration:
- Migration at low temperatures: Some plasticizers may still migrate at low temperatures (such as PVC), and long-term freezing can accelerate the release of harmful substances. Interaction with food types: Prolonged contact with oils and acidic foods (such as vinegar and lemon juice) can accelerate the release of harmful substances.
- Risks of repeated use: Reusable plastic food containers may increase the risk of chemical migration due to wear and aging during long-term use.
4.2 Thermal Stability Assessment
Thermal stability refers to the ability of plastic to maintain its chemical structure and properties under high-temperature conditions.
Thermal stability of disposable plastic microwave bowls:
- PP material: Has excellent thermal stability and can be used for extended periods at 120℃ without significant chemical changes. The thermal decomposition temperature of PP is above 300℃, so it will not decompose under normal microwave heating conditions.
- PS material: Has relatively poor thermal stability and may begin to soften above 70℃, and significant deformation and chemical changes may occur above 90℃.
- PET material: Undergoes significant thermal deformation above 70℃; therefore, it is not suitable for high-temperature applications.
It is important to note that color and patterns may affect thermal stability. Colored and patterned plastic bowls may release heavy metals and other harmful substances when heated.
Thermal stability of refrigerated plastic bowls:
- PE material: Has good thermal stability, but is prone to softening and deformation at high temperatures. The softening point of HDPE is approximately 120℃, and the softening point of LDPE is approximately 100℃.
- PET material: Although stable at room temperature, it may begin to undergo thermal deformation above 60℃. 4.3 Food Safety Certification Standards
Both types of plastic bowls must comply with strict food safety standards:
Chinese National Standard (GB 4806.7-2023) requirements:
- Sensory requirements: Normal color, no peculiar odor, no impurities; the immersion solution obtained from the migration test should be free of turbidity, precipitation, peculiar odor, and other sensory deterioration.
- Overall migration limit: ≤10mg/dm² for general food contact materials, ≤60mg/kg for infant and child-specific products.
- Potassium permanganate consumption: ≤10mg/kg, reflecting the dissolution of organic matter.
- Heavy metal content: Lead (Pb) ≤1mg/kg, Cadmium (Cd) ≤0.02mg/kg, Arsenic (As) ≤0.04mg/kg.
- Bisphenol A (BPA) migration: The limit is reduced from 0.6mg/kg to 0.05mg/kg, and its use in food contact materials for infants and children is prohibited.
- Total migration of aromatic primary amines: Not detectable, i.e., less than 0.01mg/kg.
- Decolorization test: The result must be negative, ensuring that the color does not migrate into the food.
International standard requirements:
- FDA standards: Must use FDA-approved plastic resins (such as PP polypropylene, PE polyethylene, PET polyester, etc.), complying with specific sections such as 21 CFR 177.1520.
- EU standards: Must comply with relevant regulations such as EU Regulation No. 10/2011, prohibiting the use of harmful substances such as phthalates and bisphenol A (BPA).
V. Comprehensive Comparison of Advantages and Disadvantages
5.1 Advantages and Disadvantages of Disposable Plastic Microwave Bowls
Advantages:
- Strong high-temperature resistance: Can withstand temperatures up to 120℃, and some products can reach 130-140℃, suitable for microwave heating, and is the only plastic material that can be safely used for microwave heating.
- High strength and good toughness: Not easy to break, suitable for hot food delivery scenarios. PP material has excellent impact resistance and is not easily broken under heavy pressure or impact.
- Affordable price: Low cost and high cost-effectiveness. PP material has a low density (0.90-0.91 g/cm³), making it lighter for the same volume, resulting in relatively lower material costs.
- High food safety: It is a food-grade material that meets international safety standards. PP material has strong chemical stability and is resistant to acid, alkali, and oil corrosion.
- Convenient to use: Disposable, no cleaning required, avoiding the risk of cross-contamination.
Disadvantages:
- Poor transparency: The appearance is not as transparent as PET, with a light transmittance of only about 85%, appearing milky white and translucent.
- Environmental issues: Non-biodegradable, a traditional plastic that poses a certain burden on the environment. Most disposable food containers are difficult to degrade and may take hundreds of years to decompose naturally.
- Single-use: Discarded after use, resulting in resource waste. Large-scale production and use will increase waste and put pressure on the environment.
- High-temperature risk: Even PP material may still lead to the migration and release of oligomers at high temperatures.
- Accumulated cost: Although the unit price is low, the accumulated cost of long-term use is higher.
5.2 Advantages and Disadvantages of Refrigerated Plastic Bowls
Advantages:
- Reusable: More environmentally friendly than disposable products, reducing waste. It can be reused repeatedly, is made of thickened food-grade PP5 material, and is odorless.
- Excellent low-temperature resistance: PE material can withstand extremely low temperatures from -50℃ to -70℃, suitable for refrigeration and freezing applications.
- Good sealing performance: Many products are equipped with silicone rings and multi-layer buckles, which can effectively prevent soup from spilling, making them suitable for carrying various foods.
- High transparency: PET material has a light transmittance of over 90%, which can clearly display the contents and enhance product appeal.
- Diverse materials: A variety of materials are available, including PP, PE, and PET, allowing you to choose the appropriate material according to different needs.
- Economical: Although the unit price is slightly higher, the long-term cost is lower.
Disadvantages:
- Poor heat resistance: The temperature limit of ordinary PP plastic is only 100℃; exceeding this temperature can easily cause deformation or release trace amounts of harmful substances.
- Easy to absorb stains: Plastic easily absorbs oil stains and condiment residues. If not thoroughly cleaned after long-term use, it will breed bacteria or turn yellow. Aging Issues: Repeated use can lead to aging, discoloration, and deformation, affecting the lifespan.
- Cleaning and Maintenance: Requires regular cleaning, increasing costs and time.
- Space Requirements: Requires storage space compared to disposable products.
5.3 Comprehensive Comparison Summary
Based on a comprehensive comparison of the two types of plastic bowls, the following conclusions can be drawn:
| Comparison Dimension | Disposable Microwave Plastic Bowl | Reusable Refrigeration Plastic Bowl |
| Main Advantages | High temperature resistance, inexpensive, convenient to use | Reusable, environmentally friendly, good sealing |
| Main Disadvantages | Not environmentally friendly, single-use, poor transparency | Poor heat resistance, requires cleaning, prone to aging |
| Applicable Temperature | -20℃ to 120℃ (PP) | -70℃ to 80℃ (PE) |
| Transparency | Poor (PP) | Excellent (PET) |
| Environmental Friendliness | Poor (non-biodegradable) | Good (reusable) |
| Long-term Cost | High (cumulative) | Low (amortized) |
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