GB/T 33320-2016Adhesives in food packaging materials and containers (English PDF)

3.1 Heat sealing

The technique through which food packaging materials or containers are sealed under heating conditions to achieve certain functions.

3.2 Cold sealing

The technique through which food packaging materials or containers are sealed under the conditions of normal temperature to achieve certain functions.

7.8.2.2 Sample preparation

a) dilute and mix up adhesives in accordance with the operating instructions of adhesives;

b) apply the diluted adhesives uniformly on PET films and control the adhesive applying quantity (dry adhesive quantity) at 2.0 g/m² ~ 3.5 g/m²;

c) dry the PET films applied with adhesives for 2 min at 80°C to make the solvent fully evaporate and laminate PE films through the heating roll at 50°C ~ 70°C;

d) use heating and pressure composite roll (steel roll to rubber roll, the Shore A hardness of the rubber roll not lower than 85°) to press the laminated film, with the laminating pressure >= 1.0 MPa and the temperature controlled at 55°C ~ 60°C;

e) the laminated sample is conditioned for 48 h at 50°C ~ 55°C.

7.8.3 Peel strength of solvent-free polyurethane adhesives for laminating

7.8.3.1 Film materials

As in 7.8.2.1.

7.8.3.2 Sample preparation

a) prepare adhesives in accordance with the proportion of two components in accordance with the operating instructions of adhesives and mix up;

b) apply the adhesives mixed up on PET films on the solvent-free filming machine and control the adhesive applying quantity (dry adhesive quantity) within 1.8 g/m² ~ 2.2 g/m²;

c) press the PET films coated with adhesives and PE films, controlling the temperature of heating roll at 50°C ~ 65°C, and finish laminating after cooling PET/PE laminating films;

d) conduct curing under the curing conditions specified in the product specifications (at certain temperature and within certain time) of laminated samples and cut into sample strips as standby.

8.1 Batching and sampling

Inspection is conducted by batch and a batch consists of adhesives of the same material, composition and production process. The sampling quantity is as specified in GB 20740.

8.2 Delivery inspection

8.2.1 Delivery inspection for adhesives for laminating

8.2.1.1 The items of the delivery inspection of water-based adhesives include appearance, pH, nonvolatile content and viscosity.

8.2.1.2 The items of the delivery inspection of solvent-based adhesives include appearance, viscosity and nonvolatile content.

8.2.1.3 The items of the delivery inspection of solvent-free adhesives include appearance and viscosity.

8.2.2 Delivery inspection of adhesives for extrusion

The items of the delivery inspection include appearance, vicat softening temperature and melting rate.

8.2.3 Delivery inspection of adhesives for sealing

8.2.3.1 The items of the delivery inspection of hot melt adhesives include appearance, melting viscosity and softening temperature.

8.2.3.2 The items of the delivery inspection of water-based adhesives include appearance, pH, nonvolatile content and viscosity.

8.3 Type inspection

The type inspection is a full inspection. During normal production, the type inspection shall be conducted each year, as well as in one of the following situations.

a) when the trial-manufacture of a new product is evaluated;

b) when there is any significant change in materials or production processes which may influence the product quality;

c) when production is resumed after a production halt for more than half a year;

d) when there is significant difference between the results of delivery inspection and those of last type inspection; […]