What is the difference between thermal paper and adhesive paper?
Thermal paper, to be precise, is also a type of adhesive paper. Unlike other types of adhesive paper, the key lies in the printing method. Thermal paper uses a thermal coating and does not require carbon tape printing, but has a shorter storage time. All other ordinary adhesive paper is printed using carbon tape or inkjet printing (with a long storage time).
Thermal paper is a special type of coated processing paper that has a similar appearance to ordinary white paper. The surface of thermal paper is smooth and is made of ordinary paper as the paper base. A layer of thermal color development layer is coated on top of it, all of which are coated on one side of the surface of ordinary paper. The color development layer is composed of adhesive, color developer, and colorless dye (or hidden dye), and is not separated by microcapsules. The chemical reaction is in a "latent" state. When thermal paper encounters a heated print head, the color developer and colorless dye on the printed area of the print head undergo a chemical reaction and change color, forming graphics and text. When thermal paper is placed in an environment above 70 ℃, the thermal coating will begin to change color.
Let's take a look at other adhesive papers. Taking copperplate paper as an example, the production process of copperplate paper is relatively simple. It is made by applying a layer of white coating on the surface of a piece of original paper and processing it through super calendering technology. According to the amount of coating applied, copperplate paper can be divided into two types: single-sided copperplate paper and double-sided copperplate paper; According to the different paper surfaces, copperplate paper can be divided into two types: matte copperplate paper and textured copperplate paper.
Copperplate paper has a wide range of applications, such as product brochures, books, magazines, product packaging, printed posters, promotional brochures, calendars, business cards, etc. that we often see in our daily lives. Most of them are printed and produced using copperplate paper. Copperplate paper made labels, trademarks, etc. are not only moisture-proof and have a long service life, but also convenient to use and have a long storage time, which is deeply loved by users.
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.
