Silicon sealant do you know how to deal with common problems of gluing?
1. What is the reason why neutral transparent tape turns yellow?
The yellowing of neutral transparent tape is a defect of adhesive cement itself, which is mainly caused by the crosslinking agent and tackifier in the neutral glue. The reason is that these two raw materials have "amino groups", which are extremely easy to cause yellowing. In addition, if neutral transparent tape is used together with acidic silicon sealant, it may cause the neutral glue to turn yellow after curing. It may also be caused by the long storage time of glue or the reaction between glue and substrate.
2. Why does neutral porcelain white glue become pink? Some glue changed back to porcelain white one week after curing?
This phenomenon may occur in alcohol-type gel, which is caused by titanium chromium compound, the raw material for production. Titanium chromium compound itself is red, while the porcelain white color of glue is titanium dioxide in glue, which plays a role in color mixing. However, gum is an organic substance, and most organic chemical reactions are reversible reactions, and side reactions are also produced. Temperature is just the key to cause these reactions. When the temperature is high, positive reaction will change the color, but after the temperature drops and stabilizes, the reaction will proceed in reverse to restore the original appearance. This phenomenon should be avoided if the production technology and formula are well mastered.
3. Why is there some transparent silicon sealant glue that changes to porcelain white after five days? Neutral Green Glue turns porcelain white after construction. Why?
This should also belong to the problem of raw material selection and verification of glue. Because some domestic glue is added with plasticizer, which is easy to volatilize; While some glue is added with more reinforcing filler. When plasticizer volatilizes, the strip is stretched due to shrinkage, the color of the filler is displayed (all the filler of neutral glue is white). All kinds of colored plastic are added pigment to make it become various colors. If there is a problem in pigment selection, the color of glue will change after construction; Or the color glue will be too thin during construction, A small amount of shrinkage inherent in the curing process makes the color of the glue lighter. In this case, it is recommended to maintain a certain thickness (above 3mm) when sizing.
Door and window glue, 10 common problem solutions, many people don't know!
4. Why is there a silicon sealant mark on the back of the mirror? After a period of time, there are spots or glue marks on the mirror?
There are usually three different back plating layers on the market: Mercury, sterling silver and copper. A common mirror has speckles after sizing for a period of time. This situation should be that the user has used acidic silicon sealant, while acidic silicon sealant usually reacts with the above materials, causing the mirror to see speckles. Therefore, we emphasize that neutral glue should be selected, and neutral glue can be divided into alcohol type and ketoxime type. If the copper sole mirror uses ketoxime neutral glue, ketoxime will slightly corrode the copper material. After construction for a period of time, the mirror surface can see that there are traces of corrosion in the sizing area behind, this phenomenon will not occur if alcohol neutral glue is used instead. The above are due to the improper selection of materials caused by the diversity of the substrate. Therefore, it is recommended that users should do a compatibility test to see if the glue is compatible with the material before using the glue. Select appropriate silicon sealant products to avoid unnecessary losses.
5. Some silicon sealant are shot out with grains of salt size, and some grains will be automatically resolved after curing. Why?
This is a problem in choosing the raw material formula of glue. Because some glue contains cross-linking agents, there is crystallization phenomenon in the environment with low temperature. The cross-linking agent condenses in the plastic bottle, and after being beaten out, particles of the size of salt powder will be seen, but it will slowly melt, so after curing, the granular will automatically dissolve. This situation has little effect on the quality of the glue. This situation is mainly affected by low temperature.
Door and window glue, 10 common problem solutions, many people don't know!
6. Some glue is hit on the glass, and it has not been Fixature for 7 days. What is the reason?
Most of these situations occur when it is cold. 1. The glue is too thick, Fixature slow. II. Impact of construction environment and bad weather. 3. Adhesive cement expires or has problems. 4. The glue is too soft to dry.
7. What is the reason for the bubble sound of some silicon sealant when sizing?
There may be three reasons: first, the technology is not closed during sub-packaging, and air is mixed into the plastic bottle; Second, air is left in the bottle; Third, not silicone adhesive percent, the increased fill material will have a slight chemical reaction with the PE soft glue of silicon sealant packing bottle, causing the plastic bottle to swell and increase, and the Air retained in the space will penetrate into adhesive cement to generate gaps, bubbles will sound when sizing. The effective way to overcome this phenomenon is to change the packaging of hard bottles and pay attention to the product storage environment (cool place below 30℃).
Door and window glue, 10 common problem solutions, many people don't know!
8. Why do some neutral glue appear a lot of bubbles after curing on the joint part of concrete and metal window frame in high temperature weather, while others do not? Is it a quality problem? Why didn't similar phenomena appear before?
Many brands of neutral glue have seen similar phenomena, and it is not a quality problem of glue after careful testing and repeated experiments. Because there are two kinds of neutral glue: Alcohol type and ketoxime type, and methanol contained in alcohol type glue will release gas during curing (methanol starts to volatilize at about 50℃), in particular, the reaction of direct sunlight or high temperature is more intense. In addition, concrete and metal window frames are difficult to breathe. In addition, the temperature and humidity are relatively high in summer, and the curing will be faster. The gas released by the glue can only run out of the completely solidified glue layer, bubbles of different sizes will appear on the cured strip. However, ketoxime-type gel will not release gas during curing and will not generate bubbles. However, the disadvantage of ketoxime neutral glue is that once the technology and formula are not handled well, there will be a chance to shrink and crack when it gets cold in the curing process in winter, and the technology is good, this phenomenon does not occur for those who pass the formula.
In the past, there was no similar phenomenon because in the past, construction units used little silicone adhesive in this place, and generally used acrylic waterproof sealing materials, so the phenomenon of silicone gel foaming is not very common; in recent years, silicone sealant has been widely used, which has greatly improved the quality of the project. However, due to the lack of understanding of material characteristics, improper selection of sealant causes foaming phenomenon.
To solve such problems, we should pay attention to the following points: first, the most prudent way is to do local use test first to observe whether it meets the use needs (the reaction can be seen in two or three days after General sizing); second, distinguish the use time and base material type, and choose the appropriate neutral glue use: choose ketoxime type in summer and alcohol type in winter; Third, keep the construction surface clean and dry; Fourth, when sizing in summer, avoid high temperature period (above 35℃) and direct sunlight, which is usually appropriate in the evening.
9. How to do compatibility test?
Strictly speaking, the compatibility test between adhesive and building substrate should be carried out by the building material testing Department recognized by the state, if there is such a necessary project, of course, the qualified inspection report of the National authoritative testing agency must be sufficient to determine whether to use a certain building material product, the general project can provide the base materials to silicon sealant manufacturers for compatibility testing. The structural adhesive can be tested for 45 days, and the neutral adhesive and acid adhesive can be obtained for about 35 days. The simplest and fastest way is that users can test silicon sealant on a small amount of substrate by themselves. After it is completely cured, observe the surface effect and try its peel strength by hand, to simply determine whether the adhesion and tension of the silicon sealant product meet the needs of use.
Ten. Why is acid glue easy to fall off when used on cement?
This is actually a basic problem in silicon sealant applications. Acid glue produces acetic acid during curing, which will react with the surface of alkaline materials such as cement, marble and granite to form a chalk-like substance, thus causing shedding.
