Typical Problems and Solutions of Glass Glue
1. Why does neutral transparent adhesive turn yellow?
Yellowing of neutral transparent adhesive is due to defects in the adhesive itself, mainly caused by cross-linking agents and tackifiers in the neutral adhesive. The reason is that these two raw materials contain "amino groups", which are extremely prone to yellowing; If neutral transparent adhesive and acidic adhesive are used in the same space at the same time, it will cause the neutral adhesive to turn yellow after curing.
2. Why does neutral porcelain white glue turn pink? Some adhesives turn back to porcelain white after a week of curing?
Answer: Alcohol type neutral adhesives may have this phenomenon, which is caused by the production of titanium chromium compounds as raw materials. The titanium chromium complex itself is red, and the porcelain white color of the glue is the titanium dioxide in the glue that plays a color mixing role. However, glue is an organic substance, and most organic chemical reactions are reversible, as well as side reactions. "Temperature is precisely the key to causing these reactions. When the temperature is high, a positive reaction occurs, resulting in a change in color. However, when the temperature decreases and stabilizes, the reaction proceeds in the reverse direction, restoring its original appearance.". With a good grasp of production technology and formula, this phenomenon should be avoided.
3. Some domestic transparent adhesives turn porcelain white after five days of printing? The neutral green glue turns porcelain white after construction, why?
Answer: This should also be a quality issue for the glue, as it pertains to the selection and verification of raw materials. Because some domestic adhesives contain plasticizers that are volatile; "Some adhesives have more reinforcing fillers added to them, and when the plasticizer evaporates, the adhesive strip is stretched due to shrinkage, showing the color of the filler (all fillers for neutral adhesives are white in themselves).". Various colored adhesives are made by adding pigments to make them turn into various colors. If there is a problem with the selection of pigments, the color of the adhesive will change after construction; "Or if the color adhesive is applied too thinly during construction, the inherent small amount of shrinkage of the adhesive during the curing process will make the color of the adhesive lighter. In this case, it is recommended to maintain a certain thickness (more than 3mm) when applying the adhesive.".
4. Why is it that glass glue is applied to the back of the mirror, and after a period of time, there are spots or glue marks on the mirror surface?
A: There are usually three different types of back plating for mirrors on the market: mercury, pure silver, and copper. A common phenomenon is that speckles appear on the mirror surface after a period of adhesive application. This situation should be attributed to the use of acidic glass glue by users, which usually reacts with the above materials, causing speckles to be seen on the mirror surface. Therefore, we emphasize that neutral adhesives should be selected, and neutral adhesives are divided into alcohol type and ketoxime type. If the mirror with a copper bottom is made of ketone oxime type neutral adhesive, the ketone oxime will slightly corrode the copper material. After a period of construction, there will be traces of corrosion on the mirror surface at the adhesive application point behind it. If alcohol type neutral adhesive is used instead, this phenomenon will not occur. The above are all due to improper material selection due to the diversity of the substrate. Therefore, it is recommended that users conduct a compatibility test to see if the adhesive is compatible with the material before using it. Only by selecting appropriate glass adhesive products can unnecessary losses be avoided.
5. Some glass adhesives come out in particles the size of salt particles, and some particles will dissolve automatically after solidification. Why?
Answer: This is a question of selecting the raw material formula for glue. Due to the crystallization phenomenon of the crosslinking agent contained in some adhesives under low temperatures, the crosslinking agent coagulates in the rubber bottle, and after being pumped out, particles of the size of salt powder can be seen, but it slowly dissolves, so the particles will automatically dissolve after solidification. This situation has little impact on the quality of the adhesive. This situation is mainly due to the relatively large impact of low temperature.
6. Some domestic adhesives have been applied to glass and have not dried for 7 days. What is the reason?
A: Most of these situations occur during cold weather. 1、 Gluing is too thick and drying is slow. 2、 The construction environment is affected by bad weather. 3、 The glue has expired or has problems. 4、 The glue is soft and feels like it won't dry thoroughly.
7. What is the reason for the bubble sound that occurs when some domestic glass adhesives are applied?
Answer: There may be three reasons: First, the packaging technology is not up to standard, and air is mixed into the plastic bottle; 2、 A few black-hearted manufacturers deliberately do not press the bottom cap of the bottle tightly, leaving air in the bottle but giving a sense of sufficient glue content; 3、 Due to the fact that some domestic adhesives are not 100% silicone adhesives, the added filler will react slightly with the PE soft glue in the glass rubber packaging bottle, causing the rubber bottle to swell and increase. The air remaining in the space seeps into the glue paste to create voids, which will produce an air bubble sound during sizing. An effective way to overcome this phenomenon is to change to hard bottle packaging and pay attention to the storage environment of the product (in a cool place below 30 ℃).
8. Why do some neutral adhesives appear a lot of bubbles when they solidify at the junction of concrete and metal window frames in summer, while others do not? Is it a quality issue? Why hasn't there been a similar phenomenon before?
A: Many brands of neutral adhesives have experienced similar phenomena, and careful testing and repeated experiments have confirmed that it is not a quality issue with the adhesive. Because there are two types of neutral adhesives: alcohol type and ketoxime type, and the methanol contained in alcohol type adhesives during the curing process will release gas (methanol starts to volatilize at about 50 ℃), especially when exposed to direct sunlight or high temperatures, the reaction is more intense. In addition, concrete and metal window frames are difficult to breathe. In addition, due to high temperature and humidity in summer, curing will be faster, and the gas released by the adhesive can only escape from the incompletely solidified adhesive layer. Bubbles of different sizes will appear on the solidified adhesive strip. The ketoxime type neutral adhesive does not release gas during the curing process, and therefore does not generate bubbles. However, the disadvantage of ketoxime type neutral adhesives is that once the technology and formulation are not well handled, there is a chance of shrinkage and cracking during the curing process in winter when it is cold. If the technology is good and the formulation is qualified, this phenomenon does not occur. Of course, the price of ketoxime type neutral glue is slightly higher than that of alcohol type.
In the past, there has been no similar phenomenon because in the past, construction units rarely used silicone adhesive in such places, and generally used propylene based waterproof and sealing materials. Therefore, the phenomenon of silicone neutral adhesive foaming is not very common; In recent years, silicone sealants have gradually been widely used, which has greatly improved the quality of the project. However, due to lack of understanding of material properties, improper selection of materials has resulted in foaming of the sealant.
To solve such problems, the following points should be noted: First, the most prudent approach is to first conduct a local use test to observe whether it meets the use needs (generally, reactions can be seen within two or three days after sizing); 2、 Distinguish between the use time and the type of base material, and choose the appropriate neutral glue to use: choose ketone oxime type in summer, choose alcohol type in winter; 3、 Keep the construction surface clean and dry; 4、 When applying glue in summer, avoid high temperature periods (above 35 ℃) and direct sunlight, and it is generally suitable in the evening; 5、 Similar projects can be tracked by the manufacturer's technical personnel.
9. How do I do compatibility testing?
Answer: Strictly speaking, the compatibility test between adhesives and building substrates should be conducted at a nationally recognized building material testing department. However, due to well-known reasons, it takes a long period of time and costs to submit results to these departments for inspection. For such necessary projects, it is necessary to obtain a qualified inspection report from a national authoritative testing agency at a sufficient level to determine whether to use a certain building material product. For general projects, the substrate can be provided to the glass adhesive manufacturer for compatibility testing. The test results can be obtained after 45 days for structural adhesives, and about 35 days for neutral adhesives and acidic adhesives. The simplest and fastest way is for the user to test apply the glass adhesive onto a small amount of substrate, observe the surface effect after complete solidification, and manually test its peel resistance to easily determine whether the adhesion and tensile force of the glass adhesive product meet the use needs.
10. Why is acid adhesive easy to fall off when used on cement?
Answer: This is actually a fundamental issue in the application of glass adhesive. Acid adhesives produce acetic acid during solidification, which reacts with the surfaces of alkaline materials such as cement, marble, and granite to form a chalky substance that can cause peeling.
11. What is the cause of surface wrinkling after curing of neutral adhesive?
Answer: Generally, there are several reasons: (1) The expansion coefficient of the substrate is relatively large; （2） There is displacement or vibration; （3） Some domestic adhesives themselves are too thin, and there is less filler in the adhesive and more plasticizer (white oil) is added. During the curing process, the plasticizer (white oil) has a certain degree of volatilization, which makes the volume of the adhesive smaller, resulting in shrinkage and wrinkling of the adhesive; （4） If the adhesive is too thin and can easily shrink and wrinkle after curing, thickening the thickness of the adhesive can reduce the occurrence of this phenomenon (it is recommended to apply more than 2mm adhesive).
12. What is the reason for the oil leakage of the adhesive?
Answer: Generally, the glue with oil leakage phenomenon is not of good quality, because it is not 100% silicone glass glue. It adds petroleum plasticizers to it, and the plasticizer itself is an oily substance with swelling property, which destroys the balance between the plasticizer and other components, and oil will leak out. In this case, it is best to use 100% silicone glass adhesive with good quality.
13. What is the cause of neutral glue sagging?
Answer: The main reason is that the thixotropy of the adhesive is not good, the sag is not qualified, and the adhesive feels too thin.
14. Under what circumstances can acid adhesives not be used normally?
Answer: All materials that can exude grease, plasticizer, or solvent; A tightly ventilated place; Frosted or wet surfaces; Assembly of metal and coated glass; It is not suitable for use in situations where alkaline substances such as marble, granite, concrete, etc. come into contact. "Acid silicone glass adhesives can corrode or fail to adhere to copper, brass (and other copper containing alloys), magnesium, zinc, electroplated metals (and other zinc containing alloys). It is also recommended that acidic glass adhesives not be used on items made of brick and stone materials and on carbide substrates, such as methyl isobutyrate (PLEXIGLAS), polycarbonate, polypropylene," Using this product on materials made of polyethylene and TEFLON (Teflon, PTFE) will not achieve good adhesion and compatibility. Acidic glass adhesive is not suitable for connections that move more than 25% of the joint width. It is also best not to use ordinary acid glass adhesive on structural glass. In addition, acid glass adhesive should not be used in areas where there is abrasion and substantial drawbacks. In addition, too high or too low temperature, too high or too low humidity can affect the drying speed.
15. Why is the mottled glue of the same grade more granular than the transparent glue?
Answer: This phenomenon generally occurs in domestic adhesives. Due to the fact that variegated adhesives require more pigment than transparent adhesives, one more process increases the possibility of granulation. If mixed unevenly, granular substances may occur.
16. After drying the neutral adhesive, there is something powdery on the surface. What is the reason?
Answer: Generally, there are several situations: (1) The pulverization phenomenon of the adhesive strip is due to defects in the selection of raw materials for the adhesive; （2） Uneven mixing of raw materials; （3） This may occur due to the impact of the construction environment, where more dust is easily adsorbed on the rubber surface.
17. What are the common causes of yellowing, mildewing, and blackening of glass glue in bathrooms or kitchens?
Answer: Bathrooms, kitchens, and other places are often damp and dark, and the glass glue can turn yellow and black due to mold. Therefore, neutral anti mold adhesive should be used for the bonding, sealing, and caulking of visible objects in the bathroom, including bathtubs, bathtubs, bathroom mirrors, and pipes, because the anti mold adhesive is added with anti mold agent, which can sterilize and inhibit bacterial growth.
18. What is the reason why there have been soft particles, hard lumps, and black spots in glass glue?
Answer: These three situations may occur separately or together. They are all caused by improper handling during the production or sub packaging process, as well as the mixing of solidified glass adhesive blocks or debris. Soft particles and hard lumps are caused by the formation of crusts on the surface of parts that dry quickly and are mixed with glue; It may also be caused by the scraping of the bottom and surface of the drum during repacking. Black spots are caused by unclean raw materials.
19. Why do some imported high-grade silicone acid adhesives and some aluminum plastic plates, stainless steel, and aluminum alloys have poor adhesion, while domestic adhesives stick very firmly?
Answer: Because their structural systems are different. High grade silicone acid adhesives are generally 100% silicone glass adhesives, which are made of extremely hard material and lack wettability. They have poor compatibility with some aluminum plastic plates, stainless steel, and aluminum alloys, and their curing speed is relatively fast. However, the surfaces of aluminum plastic plates, stainless steel, and aluminum alloys are very smooth and smooth, and the adhesive has cured before fully penetrating into the surfaces of aluminum plastic plates, stainless steel, and aluminum alloys, so it cannot be firmly adhered. "The curing speed of domestic adhesives is slightly slower, the penetration time is longer, and other materials such as plasticizers are added, making their properties softer. Therefore, domestic acid adhesives are easily miscible with the above materials, so they adhere more firmly.". Therefore, the better the adhesive may not have good compatibility with some aluminum plastic plates, stainless steel, and aluminum alloys, but the domestic adhesive will be better. These are all caused by the diversity of substrate materials. Therefore, we repeatedly emphasize that users should conduct a self test before using to observe whether the material meets the use needs.
20. Why does the same bottle or batch of glue have different thicknesses?
Answer: This phenomenon often occurs in poor quality glue. Due to uneven mixing of the glue and the inclusion of filler material in the glue, the filler material will drill down as soon as it sees a vacancy, resulting in a phenomenon of uneven consistency. Good mastery of production technology and formula can avoid this phenomenon. The difference in viscosity of the same bottle of glue may often be due to a reaction between the glue and the bottle, or the glue has expired.
21. When acid adhesive is applied to a stainless steel door and applied for a few minutes, sometimes the surface will blister. Why does this phenomenon occur?
Answer: The solubility of acidic adhesive with stainless steel is not good, and it is generally not recommended to use acidic adhesive on stainless steel. The main reason for blistering is the quality problem of stainless steel. In order to reduce costs, some stainless steel manufacturers make stainless steel contain more impurities, while acidic adhesives have a low pH value and strong acidity. Acidic substances can react with this type of stainless steel, so they emit bubbles.
22. Why does neutral adhesive bonding some aluminum plastic panels, plastic steel doors and windows not work well or stick well?
Answer: This phenomenon generally occurs on alcohol based neutral adhesives because the materials on aluminum plastic panels, plastic steel doors and windows do not have a good compatibility with alcohol based silicone adhesives, affecting the bonding quality. In this case, it is recommended that users choose ketoxime type neutral adhesives, which will greatly reduce the occurrence of this situation; If the user selects an alcohol based neutral adhesive, first wipe the surface of the substrate with acetone or xylene, and then apply the adhesive after the surface of the substrate is completely dry; The substrate after scrubbing should be constructed within one hour. Therefore, we have repeatedly emphasized that due to the diversity of substrate materials, users should test the compatibility between the glass adhesive and the substrate before use according to their own needs to observe whether it meets the use needs.
23. What is the reason why both ends of silicone adhesive for flexible packaging are dry and the length of dry adhesive increases with time?
Answer: The drying of both ends of the flexible packaging adhesive mainly occurs in summer. In summer, when the weather is hot, the aluminum foil layer of the packaging film ruptures under the action of external forces and internal pressure for a long time, causing moisture in the air to enter the sealant through the packaging film. The sealant will react with moisture and cause the sealant to solidify. If the fastener is not secure, it may also cause moisture to enter the sealant through the poorly sealed area of the fastener, causing both ends to dry.