De-powdering and whitening of interior wall putty powder are currently the most common problems after putty construction. To understand the reasons for interior wall putty powder de-powdering, one must first understand the basic raw material components and curing principles of interior wall putty powder, and then combine During putty construction, the dryness of the wall surface, water absorption rate, temperature, dryness of the weather, etc., find out the main reasons for the powder drop of the putty powder on the inner wall and use the corresponding method to solve the problem of powder drop of the putty powder.
The basic raw material composition of interior wall putty powder:
The most basic ingredients of interior wall putty powder include: inorganic bonding materials (ash calcium), fillers (heavy calcium powder, talcum powder, etc.) polymer additives (HPMC, polyvinyl alcohol, rubber powder, etc.)
Among them, the interior wall putty powder generally does not add white cement or only adds a small amount of white cement. Redispersible latex powder has little effect in the case of low dosage, so it is not used in interior wall putty powder mainly because of cost, or it is rarely used.
So because of the problem of the interior wall putty powder formula itself:
1. Inorganic bonding materials, such as the addition of ash calcium is too low, and the quality of ash calcium is not up to standard;
2. If the amount of the bonding component in the polymer additive is too low or the quality is not up to standard, it may cause the putty powder on the inner wall to fall off.
Divided into the following aspects:
01. The adhesive strength of the putty is not enough to cause powder removal. The manufacturer blindly reduces the cost. The adhesive strength of the rubber powder is poor and the amount of addition is small, especially for the inner wall putty. The quality of rubber powder and glue has a lot to do with the amount added.
02. The design formula is unreasonable, the problem of material selection and structure are very important in the putty formula. For example, hydroxypropyl methylcellulose (HPMC) is used as a non-waterproof putty for the inner wall. Although HPMC is very expensive, it does not work for fillers such as double fly powder, talcum powder, wollastonite powder, etc. If only HPMC is used, it will cause delamination. However, CMC and CMS with low prices do not remove powder, but CMC and CMS cannot be used as waterproof putty, nor can they be used as exterior wall putty, because CMC and CMS react with gray calcium powder and white cement, which will cause delamination. There are also polyacrylamides added to lime calcium powder and white cement as waterproof coatings, which will also cause chemical reactions to cause powder removal.
03. Uneven mixing and stirring is the main reason for the powder removal of putty on the interior and exterior walls. Some manufacturers in the country produce putty powder with simple and varied equipment. They are not special mixing equipment, and uneven mixing causes putty powder removal.
04. The error in the production process causes the putty to be powdered. If the mixing mixer does not have the function of cleaning and there are more residues, the CMC in the ordinary putty will react with the ash calcium powder in the waterproof putty. The CMC, CMS and The white cement of the exterior wall putty reacts and causes de-powdering. Some companies’ special equipment is equipped with a cleaning port, which can clean the residue in the machine, not only to ensure the quality of the putty, but also to use one machine for multiple purposes, and buy one equipment to produce a variety of putty.
05. The quality of fillers is also easy to cause de-powdering. A large number of fillers are used in interior and exterior wall putty, but the content of Ca2CO3 in heavy calcium powder and talc powder in various places is different, and the difference in pH will also cause de-powdering of putty, such as Chongqing and Chengdu’s interior wall putty powder uses the same rubber powder, but talcum powder and heavy calcium powder are different. It does not de-powder in Chongqing, but it does de-powder in Chengdu. It does not de-powder in Henan and Northeast China, but it does de-powder in some areas.
06. The reason of the weather is also a reason for the powder removal of the putty on the inner and outer walls. For example, the putty on the inner and outer walls has a dry climate and good ventilation in some arid areas in the north. Some areas have rainy weather, long-term humidity, putty film-forming properties are not good, and it will also lose powder, so some areas are suitable for waterproof putty with ash calcium powder.
07. Inorganic binders such as gray calcium powder and white cement are impure and contain a large amount of Shuangfei powder. The so-called multi-functional gray calcium powder and multi-functional white cement on the market are impure, because a large amount of these impure inorganic binders are used, and the waterproof putty of the inner and outer walls will definitely be powder-free and not waterproof.
08. In summer, the water retention of the putty on the exterior wall is not enough, especially in the high-temperature and ventilated places such as high-rise doorways and windows. The initial setting time of ash calcium powder and cement is not enough, and the water will be lost. If it is not maintained well, it will also be seriously powdered .