Let’s break it down: "plastic" in food-contact materials

"Did you hear that eating food wrapped in plastic can cause cancer?"

"Are plastic bags and plastic containers safe for holding hot food?"

"Reducing the use of plastic products may affect children's development or increase the risk of autism."

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The topic of "plastics" in food-contact materials has long been a hotly debated issue. Inexpensive and widely used, plastics are ubiquitous in the food industry—leading to ongoing criticism. So, from Food Packaging Testing From the perspective, what exactly is "plastic" in food-contact materials?

I. What is plastic?

Plastics are primarily composed of synthetic or natural polymeric compounds, with synthetic resins forming the majority of these components. According to Food Packaging Testing We know that, in addition to the basic polymers, plastic food packaging typically contains several additives, such as fillers, plasticizers, colorants, and more.

2. What are the classifications of plastics?

Plastics are classified into thermoplastics and thermosets based on how their properties change when heated, and the processing and molding of food-contact products also rely primarily on these distinct property characteristics to determine the most suitable manufacturing methods.

1. Thermoplastic plastics : Made primarily from thermoplastic resins, these materials soften when heated, harden upon cooling, and can be reshaped repeatedly. In thermoplastics, polymer molecules typically have a linear, chain-like structure. When heated, they soften and flow; upon cooling, they solidify again—this entire process represents a physical change, without any alteration in the material's chemical structure.

2. Thermosetting plastics : Made primarily from thermosetting resins, these materials undergo a process where, after being heated to soften (or melt) once and then cooled to solidify, they permanently become insoluble and infusible. Before curing, thermosetting resins typically have linear or branched structures; however, when heated to a certain temperature, they undergo cross-linking reactions, transforming into three-dimensional, networked polymer networks that give the material its rigid, durable form. Importantly, this transformation is irreversible—once cured, the material will not soften again upon reheating. Instead, if exposed to intense heat, it may break down and degrade, making it impossible to reshape repeatedly.

At Food Packaging Testing During the process, most food-contact plastic products commonly used in daily life are made from thermoplastic materials.

3. What’s the difference between thermosetting plastics and thermoplastic plastics?

The fundamental difference between thermosetting and thermoplastic plastics lies in their ability—or lack thereof—to be repeatedly reshaped through heat treatment. This is precisely why food-contact materials made of "plastic" must undergo specific testing when assessed for food packaging compliance.

1. Commonly Used Thermoplastic Plastics : Polyethylene PE ), polypropylene ( PP ), polyvinyl chloride ( PVC ), polystyrene ( P.S. ), polyvinylidene chloride ( PVDC ), Polyoxymethylene ( POMI ), polycarbonate ( PC ), polyamide ( PA ), polyacrylate, polysulfone ( PU ), polyethylene terephthalate ( PET ), polyphenylene oxide, acrylonitrile-styrene-butadiene copolymer ABS )、Acrylonitrile-Styrene Copolymer AS ) and various types of olefin copolymers, among others.

2. Commonly Used Thermosetting Plastics : Epoxy resin, amino resin, unsaturated polyester UP ) Resins, among others. Melamine-formaldehyde in amino resins MF ) and urea-formaldehyde UF ) is the primary material commonly known as "melamine tableware" or "faux porcelain tableware."

Four, what are the advantages of using plastic for food packaging?

According to food packaging testing data, plastic packaging materials, compared to rigid packaging materials like glass, ceramics, and metal:

1. Lightweight and soft in texture, resistant to tearing, easy to transport and carry, with a long shelf life, simple to store and convenient to open.

2. The material is smooth, sleek, and transparent, making it easy to print on and shape for decorative purposes—perfect for enhancing the visual appeal of products and boosting their display effectiveness.

3. By combining materials and adhesives with different properties, composite packaging can be created to tailor material performance and meet a wide range of application needs.

Plastic containers and kitchenware, compared to products made from other materials:

1. Plastics are lightweight and have low density, making them easy to mold, process, and carry around conveniently.

2. Plastic is easy to color or apply decorative patterns, resulting in a wide variety of vibrant appearances.

3. Plastic containers are affordable and offer excellent corrosion resistance, along with a certain level of mechanical strength.

4. As a mass-market product, it is widely used in everyday life.

5. What are the quality control measures for plastic products intended for food contact?

The quality of plastic food-contact products encompasses aspects such as hygiene, performance during use, and appearance. During the processing and molding stages, these factors can be effectively controlled through careful selection of raw materials and auxiliary components, as well as optimization of production processes. Food Packaging Testing Meanwhile, these indicators are typically examined and tested one by one.

1. Raw Material and Auxiliary Ingredient Control The impact of food contact materials on human health stems from the migration of their components into food. Therefore, selecting appropriate raw and auxiliary materials is a critical step in controlling product hygiene quality. The production of plastic food contact products involves a wide range of base polymers and additives, each with distinct properties and functions. These base polymers and additives contain numerous chemicals, varying widely in terms of toxicity levels, and exhibit different migration behaviors under diverse usage conditions. Moreover, regulatory requirements differ across countries. To ensure product safety, it’s essential to carefully evaluate all these factors, make informed choices about raw and auxiliary materials, establish stringent quality controls at the source, and rigorously conduct food packaging testing.

2. Selection of Base Polymers : Polymers themselves are high-molecular-weight macromolecules that are not easily absorbed by the human body. However, polymers may contain unreacted monomers and starting materials, as well as intermediate degradation or transformation products. Additionally, some polymerization aids used during synthesis can also remain in the polymer. These small-molecule substances are one of the primary sources of migration during the process. Food Packaging Testing Typically, key migration-related checks are conducted within it.

3. Selection of Additives Specifically, functional additives expected to play a technical role in the final product—such as plasticizers, fillers and reinforcing agents, colorants, stabilizers, impact modifiers (toughening agents), coupling agents, foaming agents, crosslinking agents, surface property enhancers, and specialty functional additives—are also one of the primary sources of material components migrating into food. This makes them a critical focus for testing and analysis in food packaging inspections.

4. Process Control : In addition to controlling the raw and auxiliary materials stage, combined with Food Packaging Testing The report indicates that controlling the process formulation and production techniques can also reduce the migration of material components, thereby enhancing the product's hygiene quality.