Can thermal paper come into direct contact with food?
Compared to ordinary paper, thermal paper has an additional layer of thin film on its surface and contains a special chemical component, namely latent dye. The latent dye itself is colorless, so the newly purchased thermal paper looks as white as ordinary paper.
However, when appropriate conditions arise, they will undergo a chemical reaction, and newly generated substances can absorb visible light, allowing us to see colors. For example, lipids in crystalline structures, although colorless, turn purple when exposed to acidity. This means that when we print with thermal paper, the ink in the printer is not printed on the paper.
In recent years, thermal paper has attracted widespread attention from consumers due to its BPA content. BPA is an acidic substance, so it is used as a latent dye in thermal paper, which reacts chemically with the latent dye at high temperatures to produce color; In addition, bisphenol A is commonly used as a raw material for manufacturing certain plastics or coatings. So, in using these containers, the main pathway for bisphenol A to enter the human body is to mix trace amounts of BPA from food with it. But recent studies have also shown that contact with thermal paper can cause bisphenol A to enter the human body.
For example, a new study shows that long-term exposure to thermal paper increases the level of BPA in urine.
Because the chemical structure of BPA is similar to the main estrogen secreted by the human body, estradiol, people are concerned that it may interfere with normal endocrine function after entering the body, thereby increasing the risk of many diseases. However, it should be noted that the bisphenol A content on food and thermal paper stickers is very low and will not have any impact on our body. However, although bisphenol A has not yet been banned from the production of thermal paper, many manufacturers have started using other acidic substances to replace it.
Why do thermal paper stickers fade?
Thermal paper, as the name suggests, is a type of paper that displays handwriting through thermal reactions. It does not require ink or ribbon, only heating through a thermal print head can cause the special coating on the paper to undergo a color change reaction, thereby displaying the desired text or pattern. This technology is widely used in various occasions such as supermarket price tags, delivery notes, movie tickets, etc.
However, the disadvantage of thermal paper adhesive labels is also very obvious, which is that they are prone to fading. This is because the coating on thermal paper will gradually lose its original color under the influence of factors such as sunlight, high temperature, and friction. Especially in direct sunlight or high temperature environments, the fading speed is accelerated.
What are the reasons for unclear printing on thermal paper?
1. Poor quality of thermal paper: Some cheap thermal paper has uneven ink penetration, resulting in blurry printed text.
2. Insufficient printing temperature: Thermal printers require a certain temperature to fully melt the ink. If the temperature is not sufficient, the ink cannot fully penetrate the paper, resulting in unclear printing.
3. Aging or blockage of the print head: If the print head is used or blocked for a long time, it will affect the ink ejection and lead to poor printing results.
4. Printing speed too fast: Some thermal printers may not have enough time to fully penetrate the ink into the paper when the printing speed is too fast, resulting in unclear printing.
5. Improper printing density setting: If the density set during printing is not appropriate, it can also affect the printing effect and cause unclear text.
Take you to a deeper understanding of the difference between thermal paper and copperplate paper
1. Different storage times
The storage time of copperplate paper adhesive labels is slightly longer than that of thermal paper adhesive labels, so what kind of adhesive label to buy depends on the storage time of the product you are pasting
2. Different temperature effects
Copperplate paper adhesive labels are less affected by temperature, but thermal sensitive paper adhesive labels are more affected by temperature. Therefore, if the adhesive labels attached to the surface of the product are greatly affected by temperature, printing factories generally recommend choosing copperplate paper adhesive labels
3. Different printing options
Copperplate paper needs to be printed together with carbon tape, while thermal paper does not require carbon tape printing and can be directly installed in a barcode printer for printing
4. Differences in Prices
Thermal paper is relatively expensive and can be customized according to customer needs. If there are samples, they can be printed directly based on the samples. The most important thing is that the quotation is not based on how much it costs at the beginning, but on the printing quantity. The more quantity, the more cost-effective the price
How to distinguish the quality of thermal paper?
1. Appearance: If the paper is very white, it indicates that the protective coating and thermal sensitive coating of the paper are unreasonable, and too much fluorescent powder has been added. A better paper should have a slight greenish tint. If the smoothness of the paper is not high or appears uneven, it indicates that the coating on the paper is not uniform. If the paper appears to reflect strong light, it is also due to the addition of too much fluorescent powder, resulting in poor quality.
2. Fire baking: The method of fire baking is also very simple. Use a lighter to heat the back of the paper. If the color appearing on the paper after heating is brown, it indicates that the heat sensitive formula is not very reasonable and the storage time may be relatively short. If there are small stripes or uneven color blocks on the black part of the paper, it indicates that the coating is uneven. High quality paper should be black green (with a hint of green) after heating, and the color blocks should be uniform, gradually fading from the center to the surrounding areas.
3. Comparison and identification of sunlight exposure: After applying a fluorescent pen to the printed paper, place it in the sun to accelerate the reaction of the thermosensitive coating to light. Which type of paper turns black the fastest indicates a shorter shelf life.
