The strengthening of national environmental protection awareness, on the one hand, the whole society advocates cleaner production, and requires the entire life cycle of the product to achieve energy saving, consumption reduction, pollution reduction, and efficiency improvement; on the other hand, in order to meet the needs of green packaging, it requires packaging. Product safety, hygiene, and good adaptability to environmental protection can save resources. The production and use of paper cups is in line with the national environmental protection policy. The use of paper cups instead of disposable plastic cups reduces “white pollution”. The convenience and hygienic quality of paper cups is the key to replacing other utensils in the market. Paper cups are divided into cold drink cups and hot drink cups according to their purposes. In addition to meeting the needs of their packaging processing performance, the materials of the paper cups must also satisfy their printing adaptability. In the printing technology, many factors must also meet the paper cup processing heat sealing conditions. The paper will discuss some issues concerning the material composition and printability of paper cups.
Composition of paper cup material
The production process of the cold drink cup is directly printed by paper cup base paper, die-cutting, forming processing, and double-sided lamination. The production process of the hot drink cup is the lamination of paper cup paper into paper cup paper, printing, die-cutting and forming processing.
1 paper cup base paper composition
The paper cup base paper is composed of plant fibers, and its production process is generally through the use of plant fibers such as softwood, hardwood wood, etc., through pulping, pulp refining, adding chemical auxiliary materials, screening, and paper machine copying.
Composition of 2 paper cups
The paper cup paper is composed of paper cup base paper and plastic resin particles. The plastic resin generally uses polyethylene resin (PE). The paper cup base paper is single PE paper cup or double PE paper cup paper after laminating single-sided PE film or double-sided PE film. . PE has its own non-toxic, odorless, odorless; reliable sanitary performance; chemical stability; balanced physical and mechanical properties, good cold resistance; The advantages of heat sealing and other properties. PE has a large amount of production, convenient source and low price, but it is not suitable for high-temperature cooking. If the paper cup has special performance requirements, plastic resins with corresponding properties should be selected when laminating.
Printability of paper cups
1 Cup substrate requirements
1.1 Surface requirements of paper cup base paper
The directly printed paper cup base paper should have a certain surface strength (wax stick value ≥ 14A) to prevent the appearance of hair fall off during printing; at the same time, it must have good surface fineness in order to meet the uniformity of the print ink.
1.2 Surface treatment before printing
The base paper or base film to be printed must have a clean, dry, flat, dust-free, and oil-free surface. For materials such as non-polar and smooth-surfaced PE, the surface tension is low, only 29 to 31mN?m-1, but also corona treatment in advance, so that its surface state changes, surface tension increased to 40mN?m-1, at least 38mN?m-1, so that printing ink can reach a certain degree of prison degree.
2 Paper cup printing ink requirements
Printing inks for paper cups require better printing fastness, good acid and alkali resistance, water resistance, temperature resistance, and light resistance, and will not fade, discolor, or peel off due to the effects of these factors; other prints should have good Scratch and gloss, semi-dull and matting.
Paper cup printing technology (Supplement to general printing technology)
1 Ink components: The components of the ink must comply with the Food Sanitation Law and the corresponding food packaging hygiene standards.
2 Residual solvent: The amount of residual solvent should be controlled to a small extent to prevent odor from being produced in the printed matter. When the backside of the printed material is contaminated and the solvent adheres to the base material or base film of the seal, it will cause poor heat sealing and form a seal joint. Poor or badly made due to bad cohesion.
3 Drying temperature: The drying temperature of the ink cannot be too high. When the temperature is too high, over-oxidation occurs on the surface of the base film, resulting in poor heat sealing. However, it is also necessary to prevent printing ink from drying badly to avoid odor.
4 ink and ink solvent selection: the use of ink solvents as possible can not make the PE film swell or solvent water, in order to prevent curling of the printed matter; as far as possible the use of plastic containing free carrier ink to prevent ink film and PE film due to temperature changes The resulting shrinkage is different and forms a printed curl. The curled prints are warped after die-cutting into fan-shaped pieces, making it difficult to convey and wind-up the cups.
5 Ambient temperature and humidity: If the humidity of the workshop is too high, the curl of the printed matter will be formed. If the temperature of the rolled film after printing is too high, the adhesion between the upper and lower layers of the film will occur, which will also affect the subsequent processing of the paper cup.
Paper cup processing performance
According to the paper cup processing performance and use performance, it is determined that the paper cup base paper must have the following technical requirements:
1 strong water resistance: made of paper cups without water seepage, water leakage phenomenon.
2 easy processing and forming: when making paper cups, in order to avoid paper jams and wrinkles during the production process, and the deformed paper cups are not easy to be deformed, it is required that the base paper of the paper cup has high stiffness, good flatness and proper looseness, and is easy to be processed and formed.
3 Paper surface exquisiteness: It is required to control the surface roughness value of the base paper to be printed on the printing surface or the laminating film PE in order to meet the surface exquisiteness required for printing on the paper cup surface.
4 High brightness: Under the premise of not using fluorescer, the original paper should maintain the corresponding paper whiteness to ensure the clear and beautiful printing pattern.
5 High safety and health: Paper cup paper and paper cup products are regularly sent to the local national health and epidemic prevention system for health and safety testing to ensure the safety of users. The paper cup base paper complies with the Hygienic Standard for Food Packaging Paper (GB 1 1680), paper cups. The paper complies with the "Hygienic Standards for Polyethylene Products for Food Packaging" (GB/T 9687). Meanwhile, the products (including special plastic particles) must also be sent to relevant institutions for the quality inspection of the lZDA to ensure that the national hygiene standards are met in terms of hygiene and safety. And meet the requirements of foreign users.
in conclusion
Paper cups are food packaging materials and are in direct contact with the population. In terms of hygiene, they must meet hygienic standards. The heat sealing performance of the continuous forming process of paper cups and the printing on the PE film surface require the incorporation of the paper technology and the performance of the paper cup. Appropriate ink composition, residual solvent amount, moderate drying conditions and other factors.
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