The main components of PU oil: propionic acid resin + Hardener;
The main components of gorgeous oil are: Lacquer + Hardener
Hardener can be divided into yellowing and yellowing resistance. Some customers need the PU oil with harder which possesses yellowing resistance.
PU paper’s Physical properties:
(1) Scratch resistance, tested with the special abrasion tester.
(2) Dirt resistance, tested with coffee, alcohol, liquid paraffin, etc.
(3) Stickiness resistance, tested with special adhesive tape.
The surface of PU paper or matt PU paper is easy to produce base paper fiber or sticky paper, the main reason is that too much PU oil coating on the surface and the drying time is not enough. After printing, PU paper needs to be dried in an oven at 50 ℃ for at least 72 hours to achieve the best physical properties. The purpose of baking is to make propionic acid resin and hardener better adhesive.
PU paper is divided into matte and bright according to brightness.
Full mute — 6-10 ° semi mute — 15-20 ° high brightness — above 35 °
Gorgeous paper is usually highlighted, with the highest brightness of about 40-43 degrees. The quality of the paper also determines the brightness. The highest brightness of the Hengda paper is about 5 ° higher than that of Jinrui.
4.Printing color standards:
(1) Check the surface color of the paper sample
(2) Check the oil scraping and color matching of the paper sample
(3) Color matching of hand pasted board
The lower the weight of the paper, the more likely to produce the phenomenon of penetration, which affects the color of the pasted board. When you meet customers with high requirements for color, you need to know that the difference between basic materials and the phenomenon of penetration has a great impact on color.
(1) PU paper is suitable for high or low temperature pasting (temperature 50-100 ℃), while gorgeous paper is only suitable for low temperature pasting (temperature 50-60 ℃)
(2) The Pasting process is divided into manual paste and machine paste. The machine is generally a sticker machine, which uses white latex to realize the adhesion of paper and board.
6.Problems in subsequent processing:
PU paper and gorgeous paper are finished paper, which do not need subsequent painting treatment; in a few cases, full dumb PU paper can be sprayed with a small amount of paint to improve the surface effect.
7.Type of PU paper:
Our main varieties are:
Single PU, double PU; single matt Pu, double matt Pu, DPU, etc.
The coating amount of single PU and double PU is as follows:
Single Pu — 3.25-3.75g/m2;
Double Pu —- 6-7g/m2
In printing, the increase of weight should be determined according to the color depth, the number of rollers and other factors. There is no uniform standard.
When we discuss the weight with customers, we must know whether it is the weight of base paper or finished product.