Why carbon free carbon copy paper turns yellow

Carbon free copy paper contains CF layer and CB layer with chromogenic agent. The developer and chromogenic agent will turn yellow when they are oxidized with oxygen in the air, sunlight or high temperature for a long time. Carbonless copy paper is a kind of hidden color copy paper, which has the function of direct copying and color developing. Under the action of external force, the force sensitive pigment and oil solution in the microcapsule overflow and react with the chromogenic agent after contacting, thus playing the role of copying. It is mainly used for multiple forms, bills, continuous bills, general business bills, etc. The handwriting of the copy is clear and distinct, which can prevent alteration and imitation.

It does not pollute fingers, clothes and other stationery paper, keeps clean and clean; it has various colors and is easy to identify and deal with; the paper is excellent, smooth and smooth, stronger than 28g color printing paper, not easy to be damaged, and the printing color is gorgeous; it does not contain harmful raw materials and peculiar smell, and is safe and reliable, and the pictures and texts can be stored for more than 15 years after color development. Chromogenic agent is a special colorless dye, which has been dissolved in non-volatile carrier oil and encapsulated in 3-7 μ m microcapsules. The impact pressure of hard writing and printing can crush the microcapsules, make the colorless dye solution flow out and contact with the color reagent, produce chemical reaction, and present colored pictures and texts, so as to achieve the purpose of copying. According to the color of paper, it can be divided into five kinds: red, yellow, green, blue and white; according to the color trace, it can be divided into blue, yellow, orange, black, red and so on.

In the case of triple carbon free carbon copy paper receipt, it can be divided into paper on, paper in and paper out. The upper paper is also called back coated paper, the back of the paper is coated with microcapsules containing force sensitive pigment oil; the medium paper is also called positive and negative double coated paper, the front side of the paper is coated with color developing agent, and the back side is coated with microcapsules containing force sensitive pigment oil; the lower paper is also called top coated paper, and the paper surface is only coated with color developing agent. Self developing paper is coated with microcapsule layer containing force sensitive pigment oil on the back of paper, and coated with developer and microcapsule containing force sensitive pigment oil on the front. On the paper and under the paper is not a copy effect, only in the paper can have a copy effect. When using the documents printed by carbon free carbon copy paper, a small piece of paperboard is usually used to separate the sheets, so as to avoid the excessive writing force which may cause other sheets to be copied to the bottom.

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