Glass is easy to mold its structural features decisions. Especially in the south of the Yangtze River, due to high temperatures lasted long, the humidity of the climate, it is more likely to lead to the glass mold. Glass mold glass component structure involves complex factors, manufacturing processes, storage and climatic conditions, there is no feasible way to eradicate the glass mold, glass mold remains an industry problem. According to statistics, the country due to the loss of moldy glass over one million tons. This collection of domestic glass companies common mold method, focusing on measures for the product after mold process, rather than to investigate the chemical stability and mildew problems before the process of glass.

1.mold-liquid method

The method is to mold spray or brush on the surface of the glass, the glass surface layer covering film, the use of antifungal solution to neutralize acidic glass surface bases, to mildew effect. This method is commonly used in PPG joint venture or the introduction of technology production lines in Guangdong as early float glass and later informed, Fuyao float. Since the mold was minimal wetting angle glass surface, and can fully wet glass surface, so the higher its antifungal properties. As we all know, PPG formulations in order to lower aluminum (<0.5%) Characteristics of poor chemical stability of the glass body, but with mildew liquid antifungal effects of their products from years of customer feedback, is not inferior to aluminum (1%), the formulation of glass, temperature and humidity box by laboratory experiments also proved this point. Usually smooth surface mold measuring instrument to measure the thickness and uniformity of liquid in the glass surface, the thickness of the claim 40 to 50, which is a contrast parameter, which is to measure the smooth glass surface data, there is mold was covered and then measure the glass surface data, the difference between them is the cover thickness. Disposable devices mildew liquid investment law is not large, mainly spray room, spray gun system, exhaust system, with hydraulic cylinder, but a larger area. Shortcoming mildew liquid method, one surface of the liquid crystal mold, poor appearance of the flu, can cause high-end customers, especially Japanese customer dissatisfaction; the second is an acid will corrode the metal surface of the glass mold liquid droplets produce spots . Fortunately, the Shenzhen company in the absorption liquid method PPG mildew on the creative use of neutral liquid mildew by absorbing glass mold base early, a protective film is formed on the glass surface. Click the mechanism should be able to avoid mildew liquid on the surface of the metal drip corrosion, mildew is a progressive tradition was law.

2. the chemical reaction

The method is to spray the liquid chemical chemical reaction on the surface of the glass, on the one hand to reduce the alkali metal ions by ion-exchange surface of the glass, on the other hand the chemical liquid metal ion is replaced by a larger ionic radius into the glass surface, to improve the the density of the glass surface, so as to achieve the effect of mildew. Widespread use of this method, such as early and later in Shanghai, Tianjin SYP NSG NSG in PILKINGTON joint venture or the introduction of technology and production lines .. From years of customer feedback, the antifungal effect of this law is relatively good, and the smooth glass surface, the appearance of good sense. But a one-time investment in equipment and operating costs of this method are quite large, and the reaction process and control requirements more stringent cleaning, a little mistake will generate a surplus in the glass surface salts thereof, itself becomes defective. This product shop paper, it is easy to form a paper profiling. Such cases are not uncommon in customer complaints.

3. mold powder method

The method is through a dedicated spray, sprinkle powder mildew isolation device powder evenly sprinkle on the glass surface, use powder acidic substances "acid field" around the particles, thereby delaying the glass mold. Powder effective mold material is usually an organic acid, such as boric acid, adipic acid, maleic acid, benzoic acid and the like. Although the effects of mildew mold powder formulations with acid, but also on the particle size distribution of a great relationship. At present, the main mold isolate powder according to particle size can be divided into two categories: fine type and meal type, such as former German F5B, British Lucite (LUCITE) and Nanjing Geli Seoul, an average particle diameter in between 60 to 70 microns, the latter of L PPG powder and treasure Manchester Shenzhen, the average particle diameter of between 130 to 140 microns. Under the premise of a certain amount of powder, the powder diameter and covering an area of a linear inverse relationship, the smaller the particle size of the powder, the greater the sum of the areas covered, the protection of the greater area of the glass, the higher the efficiency of powder. But meticulous parts in the course will produce more flying, so as to reduce the amount of powder actually remain in the glass surface. Powder and glass is solid with solid contact, so the effects of mildew mildew mold powder is not as liquid and chemical reaction, but it is its effect on the glass surface of the weak, substantially changing the surface properties of the glass, which meet those There are high demands on the glass surface of the high-end customers. Disposable equipment investment and running costs mold powder method is the lowest of all, one-sixth of the cost of paper law only shop, but also in line with the trend of social development, environmental protection, and therefore the law has been developing rapidly in recent years.

4. jammed law 

1. The method is glass packaging, artificial spread the paper on the glass surface, relying on acidic paper to slow down the rate of corrosion of glass. Paper can absorb moisture, but also to avoid the erosion of water vapor on the glass surface. There are certain buffer paper, broken glass can be reduced in the circulation process. Jammed law float glass production line in general the most widely used. Jam law disadvantages:
2.  Prone paper profiling can not be cleaned, can not meet the mirror, coated glass deep processing requirements
3. Easy to fold as the paper is difficult to completely flat against the glass surface of the ground, mildew effect is not high;
4.  Paper in the varnish and sand and other hard objects can cause the glass surface quality problems even affect the use of glass;
5. Although disposable equipment investment is low, but operating costs (including paper and labor) is very high;
6. Consumes a lot of wood, does not meet the trend of social development and environmental protection.
7. Comprehensive comparison of the four law

5. vacuum packaging method

 The method commonly used in the food industry, mainly used in glass industry for ultra-white glass. The method is based on the above mold method, using thick plastic film when the package wrapped in aluminum foil or glass, after removing the internal air seal, have an impact on the glass to prevent minor gas leak after placing a certain amount of desiccant bag . Practice at home and abroad show that the significant effect of the glass mold, the domestic one company using this method, the ultra-white glass placed almost no moldy after one year. There are also some high-end glass processing customers to adopt this approach. The disadvantage of this method is that the material (aluminum foil) and higher labor costs.

6. the surface film law

This method is used for coating of the product, in order to prevent oxidation and moldy film, a film put on the surface of the glass, isolated air. Due to the high cost, this method is not suitable promotion to float glass.

Conclusion

                                                                                               From "glass industry" 2009.08 

                                                                                                By Wu Yelin