Glass bottle surface treatment

In the last issue, we introduced the glass bottle production process. Next, we will introduce the surface treatment of glass bottles. Reminder: For those who have not read the previous issue, it is recommended to read the previous issue first, which will be helpful for reading this issue.

For the surface treatment of glass bottles, there are mainly two processes, one is coating and the other is printing. The following introduces the situation of the two processes respectively, and first introduces the coating process. After the glass bottle is formed and before cooling (about 800°C), spray metal oxide (organic tin oxide) on the surface of the bottle body to repair the fine cracks on the bottle body and form a protective film on the surface. To improve the mechanical impact resistance of empty bottles, this process is called thermal coating. It has been proved by experiments that the strength of glass bottles can be increased by about 55% by thermal coating.

After the empty bottle is cooled, spray polyethylene on the surface to improve the wear resistance of the surface and avoid abrasion, and at the same time, the strength of the glass bottle is also improved to a certain extent. Spraying the etchant on the surface of the bottle can form a frosting effect on the surface of the bottle and improve the appearance of the product. However, if the empty bottle has been cold/hot coated and there is a protective film on the surface, the etchant will not be able to function, and the frosting design cannot be performed.

Another surface treatment process is introduced below, which is printing. The decoration on the surface of the empty bottle includes labeling, sleeve labeling, and printing, among which printing can be divided into two methods: screen printing and thermal transfer printing.

Screen printing is generally about 3 colors, up to 8 colors. The more common three-color curved surface screen printing machine on the market is suitable for printing beer bottles, beverage bottles, and glasses, and can solve the problem of inaccurate color registration without positioning points.

Glass heat transfer printing refers to the use of a special heat transfer machine to quickly transfer the graphics and texts printed on the heat transfer film to the surface of the glass bottle under the condition of heating and pressure. And through proper baking (180 ℃, more than 40 minutes, if the temperature is increased, the baking time can be shortened), the graphics and texts are firmly combined on the surface of the glass bottle, and the shape of the glass bottle is usually required to be a single curved surface. The transfer process is completed automatically or semi-automatically under the electric eye tracking, so the positioning is accurate and labor is saved. The transferred layer has excellent characteristics such as acid and alkali resistance, water resistance, peeling resistance, and alcohol wiping resistance.

Heat transfer printing film is the key to the whole glass heat transfer process, it is composed of PET film substrate, separation layer, protective layer, ink layer and adhesive layer. This kind of flower film is printed by gravure printing, and the resolution of the printed image and text can reach 175 lines to 200 lines, which is very fine, and can also express metallic lines or patterns. The product packaging form of the flower film is in the form of a roll. During the thermal transfer process, only the graphic part of the flower film can be completely transferred on the glass surface, while the film substrate is peeled off.

Since the ink layer of thermal transfer printing is basically composed of organic materials, it is bonded to the glass surface by organic hot-melt adhesive, which is different from inorganic sintering ink. Therefore, the following items must be paid attention to during the use of the transferred glass bottle:

(1) Try to avoid friction with sharp objects or objects with rough surfaces;

(2) The products are preferably separated by packaging during transportation;

(3) Appropriate protection should be carried out according to the actual situation in the subsequent production process, such as avoiding severe friction and scratching when filling glass bottles. For some products such as rice wine, fruit juice, etc. that require high-temperature sterilization, the bottles should be separated and protected during the process to avoid friction and collision.

The surface treatment of the glass bottle has been explained to everyone. In the next issue, I will introduce the precautions for the design of the glass bottle.We welcome more people to pay attention to our company, ZHUHAI BAOLI FOAM SPRAY PUMP CO.,LTD.

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