Industry News

Coffee paper cups, milk tea paper cups, juice paper cups and other paper cup products can be found everywhere in our daily life. The high demand for paper cups in the food industry continues to attract paper cup manufacturers to expand their production. So, how are food-grade paper cups produced? In this article, we will introduce you in detail from substrate selection, coating, flexographic printing and die cutting, cup forming, sterilization and packaging.

Stack Type Flexo Printing Machine for PE Coated Paper Cups

Substrate Selection

Virgin pulp paper should be purchased from large source paper mills as the substrate for paper cups. Virgin pulp paper is usually made from fresh wood fibers. Wood fiber has few impurities and low content of harmful substances, and no fluorescent whitening agent is added in the production process, which is very pure and suitable for the production of mousse paper cups, cupcake paper cups, pudding paper cups and other food packages; the wood fiber is long and tough, with high strength and high toughness, and is able to hold larger food products. It is suitable for producing bubble tea paper cups, coke paper cups, beer paper cups and other beverages packaging, and is not easy to break or deform.

CI Type Flexographic Printing Machine for PLA Coated Paper Cups

Coating

Coating has a pivotal role in the process of making paper cups. Coating virgin pulp paper can make them safer, more waterproof, more oil-proof and more environmentally friendly. Currently, common coating materials include PE (polyethylene) coating, PLA (polylactic acid) coating, etc. The selection of coating raw materials should be combined with the needs of cup usage, cost control, environmental protection requirements and other aspects.

Coating Machine of Jiangsu Laiyi Packaging Machinery Co., Ltd

PE Coating - the Most Commonly Used

As the most commonly used coating material, PE coating can be made into single PE coated paper and double PE coated paper. Single PE coated paper is made by coating on one side of the paper, which is low cost and suitable for making wine beverage paper cup, Cola paper cup, sprite paper cup and other cold drink paper cups; double PE coated paper is made by coating on both sides of the paper, which is more resistant to high temperature and anti-penetration, and suitable for making hot chocolate paper cup, cappuccino paper cup, ginger tea paper cup and other hot drink paper cups.

PE Coating has now entered a mature and stable stage of use, with low cost and high adaptability to printing to obtain most of the paper cup manufacturers. But at the same time, it also has the disadvantages of non-degradable, difficult to recycle, not environmentally friendly, etc. It should be used with caution in countries with strict environmental regulations.

Stacking Type Flexo Printing Machinery for Milkshake Paper Cups

PLA Coating--Biodegradable

PLA is extracted from pure natural resources such as corn starch and can be completely degraded, which can contribute greatly to environmental protection. It is non-toxic and tasteless, and meets the food contact safety standard, which is very suitable for making ice water paper cup, yogurt paper cup, chicken soup paper cup and so on.

Stacked Flexo Press for Soda Paper Cups

Flexographic Printing and Die Cutting

Flexographic press can be equipped with die-cutting unit, integrating flexo printing, die-cutting and other multi-functions. The coated virgin pulp paper can be printed with fine patterns and texts by printing machine, dried in the drying system and then die-cut into fan-shaped cups by the die-cutting unit. This series of processes requires attention to details such as machine commissioning, ink management, print quality monitoring, imposition and die-cutting.

Die-Cutting Unit of Vertical Stack Flexo Printer for Popcorn Paper Cups

Machine Commissioning

Latte paper cup, ice cream paper cup, jelly paper cup, lemonade paper cup, etc. require high printing accuracy. Therefore, before the plate mounting and printing of the flexographic printer, it is necessary to carefully clean the printing plate and other components, adjust the pressure between the anilox roller, plate roller, printing roller, and keep the tension control stable to avoid overprinting inaccuracy during the printing process.

Printing Unit of Stacking Flexography Machine for Soy Milk Paper Cups

Ink Management

Flexo presses generally use water-based ink for flexo printing. Water-based ink has low viscosity, good fluidity, and is good for environmental protection and harmless to human body, which is very suitable for the printing of cold beverage paper cup, hot apple cider paper cup, black tea paper cup and so on. When printing, the printing speed and drying speed should be selected according to the characteristics of the substrate and the viscosity of the ink to avoid ink accumulation or uneven drying.

Print Quality Monitoring

During the printing process, pay attention to the video inspection system of the flexographic machine and make regular sampling checks to ensure the printing quality. If you find the dot gain and other problems, timely adjust the printing pressure or ink parameters.

Video Inspection System of Paper Cup Printing Machine

Imposition and Die-Cutting

Special attention should be given to the preparation of pressure strips during plate imposition for flexographic printing. It can be used to hold the printing plate in place to prevent it from moving during printing, and to ensure the accuracy of the die cutter when die-cutting to avoid uneven cuts.

Cup Forming

The fan-shaped cup forming process is mainly divided into side wall curling, bottom insertion, rim curling and bottom sealing. High-temperature resistant structure, thermal curing, knurling, bonding and other operations can ensure the quality of paper cups.

Paper Cup Forming Machine of Zhejiang Discover Machinery Manufacturing Co., Ltd.

Side Wall Curling

The fan-shaped cup pieces is rolled into the wall of the cup by means of the sleeve and high-frequency vibration of a paper cup forming machine. During the side wall curling process, the PE film at the seams of the fan-shaped cup pieces is fused and glued together by means of hot pressing.

Paper Cup Forming Machine of Zhejiang New Debao Machinery Co., Ltd.

Bottom Insertion

The cup bottom and wall are heated and pressed by a paper cup forming machine for gluing.

Paper Cup Forming Machine of Michael Hörauf Maschinenfabrik GmbH & Co.KG

Rim Curling and Bottom Sealing

After the paper cup is formed, rim curling is needed for the cup rim, which can enhance the firmness and beauty of the cup rim, especially suitable for strawberry mousse paper cup, caramel pudding paper cup, nut yogurt paper cup and so on, which have higher requirements on the appearance. It is especially suitable for strawberry mousse paper cup, caramel pudding paper cup, nut yogurt paper cup and other paper cups which require high appearance.

Sterilization and Packaging

For safety reasons, food-grade paper cups need to be sterilized after forming before packaging to ensure that they meet food safety standards.

Sterilized paper cups are usually packaged in sealed plastic bags. This packaging not only isolates the cups from dust and microorganisms, but also protects them from moisture, keeping them dry and clean.

Kraft Paper Cup Printed by Central Impression Flexo Printing Machine

In a word, the production of food grade paper cups is a complex and delicate process, from the careful substrate selection to a series of processes such as coating, flexographic printing, die-cutting, forming, sterilization and packaging, each step needs to be strictly controlled. Only in this way can the quality and safety of hot water paper cups, vegetable soup paper cups, etc. be guaranteed. It is these rigorous production processes that allow food grade paper cups to meet the needs of our daily lives and the food industry, and become an indispensable part of our lives.