Definition of putty:
putty is a thick material used to eliminate pores or other defects in the base surface before coating coating, generally considered to be a coating matching material.
putty is generally used on primer, its main role is to fill the grass, for coating to provide an ideal floor. The rougher base is used to form a thicker putty film by applying multiple puttys to
. Putty film after grinding, into a flat, smooth surface, for the surface coating coating paint to provide a good foundation, not only to reduce the amount of paint, but also to make the coating film with good decorative effect.
type of putty is related to the type of coating. For example, automotive paint putty, mechanical coating putty, building putty, etc. Among them, the building putty is divided into wall putty, floor putty, pull hair putty and so on. In the building putty, from the use of the amount, the largest or wall putty, one is that the wall grass is usually poor flatness, the unit area putty use is large; Second, the need to paint the use of putty building wall area is large; In terms of variety, the most is the wall putty.
putty performance requirements
putty variety, from the common characteristics of putty, putty should have the following performance:
(1) viscosity is appropriate, easy to scrape, scraping when not rolling edge, good construction performance; (2) be able to self-dry (some putty also requires fast drying), dry performance is good; Good tentacle performance, low dry shrinkage; (4) good filling performance, delicate surface; (5) good polishing performance, grinding without rolling edges, non-stick sandpaper; (6) Putty film has good mechanical strength, has a certain flexibility, itself is not easy to crack, at the same time can cover the grass-roots micro-cracks, and resist the grass-roots micro-crack size changes; (7) with the primer matching, has good protection performance; (8) Putty for indoor environmental protection performance is good, can not contain (especially after drying) harmful substances to the human body or the environment.
the characteristics of putty
putty performance is different from paint, from its composition, construction performance, putty film performance, economy, technology, dosing and so on, have significantly different characteristics from paint.
The composition of putty characteristics
putty composition material, the type of film-forming substances than the paint is much less, its dosing is very low, the body pigment occupies a large proportion, its pigment volume concentration PVC value of up to 80% or higher. In addition, for most putty, the quality of the body pigment (e.g. whiteness, fineness, etc.) requirements are much lower than the paint; For some puttys (e.g., coarse flat putty with filling as the main function), it is even better to require the fineness of the body pigment. This material composition characteristics of putty make putty from scraping the paste to change into a dry putty film process, will not produce a large volume contraction, thus ensuring that putty film can be coated very thick and not cracked in the drying process, which is very beneficial for putty filling rough grass.
the bonding performance of the grass
putty to the base bonding performance is the importance of putty energy, directly affect the use of putty. Putty is generally required to bond firmly to the base to ensure that the paint in the process of use putty film will not fall off from the grass
the putty construction performance requirements are lower than the paint. Usually require putty has a good tentacle and consistency, because putty is more than the use of batch coating method construction, the approval performance requirements are usually easy to batch coating, not sticky, not rolling edge, batch coating a certain thickness will not produce flow hanging, with appropriate drying time to meet the local rest after batch coating. In addition, putty is also required to have good polishing after drying until the final strength is reached.
Desty layer dry performance
As far as the wall putty is, because the wall base is cement-based material, with a high alkaline, therefore, putty film should have good alkaline resistance, water resistance, and have a certain mechanical strength. Putty membranes are sometimes required to have certain special properties, such as crack resistance, flexibility, etc. But in general, the physical and physical properties of putty membrane is worse than the physical and physical properties of coated film
pym environmental performance
putty can not contain toxic and harmful substances to human body or the environment, putty for the inner wall of toxic and harmful substances limit should meet the national standard GB18582-2020 requirements
The amount of putty unit area is large, and is also coated supporting materials, should have reasonable costs, economics is not good, will affect the use of putty
There are fewer kinds of inner wall putty, the requirement of its physical and technical performance is lower than that of outer wall putty, but the requirement of inner wall putty is higher than that of outer wall putty in its easy scraping, delicateness of putty film, etc. In addition, for the same building, the interior wall needs to be coated in a much larger area than the outer wall, so the actual use of the inner wall putty is also larger than the outer wall putty.
According to the construction industry standard "Building indoor putty" (JG/T298-2010) provisions, according to its applicable characteristics and according to the main physical and mechanics of putty film performance, the inner wall putty is divided into general type, flexible type and water-resistant type three categories. General inner wall putty is suitable for general interior decoration projects, with the symbol Y; Flexible interior wall putty is suitable for indoor decoration projects with certain cracking requirements, indicated by the symbol R; Water-resistant interior wall putty is suitable for indoor decoration projects that require water-resistant, high bonding strength, represented by the symbol N.
The inner wall water-resistant putty formula analysis
so that putty has bonding strength of the main material is glue material, currently in the dry powder putty application is more divided into two categories of materials: one is inorganic materials, such as white silicate cement, cooked lime; Gray calcium powder, white cement do cement materials have a wide range of sources, cheap and other advantages, but they are strong alkaline materials, simply with such materials scraping walls will be due to large shrinkage and cracking, paint flowering and other quality problems, used more in the past, is now basically not alone as glue material. Organic powder has the characteristics of rapid dissolution in cold water, good bonding performance, in recent years, more and more use in putty, but because of the use of separate glue material, putty water resistance is poor, easy to appear powder, peeling and other phenomena, thus affecting the use of function. Therefore, combined with the inorganic materials and organic materials of their respective advantages, the preparation of high-performance building putty is the main direction of current and even future development.
filler is the largest amount of material used in putty, putty scraping, polishing, etc. will have a greater impact. At present, putty inert fillers mainly have heavy calcium carbonate, light calcium carbonate, talcum powder, etc. , the main requirements are a wide range of sources, cheap, fineness and whiteness have certain requirements. At present, the basic choice of thick particle size of heavy calcium carbonate, a small amount of light calcium carbonate and talcum powder for fillers to prepare dry powder putty. Because a large number of coarser particle size of heavy calcium carbonate is not only conducive to reducing the cost of putty, but also the particle size is coarser, the need for glue material is relatively reduced, or in the case of the same amount of glue material dosing putty performance can be relatively improved;
(1) water thickener
putty water preservation is directly related to its batch scratching, with a good water preservation effect putty batch scraping soft, time-saving, labor-saving, so water preservation The selection of materials is very important, the current commonly used materials are mainly various types of cellulose ether, these materials are widely sourced, easy to use, is currently the putty industry with water preservation agent mainstream products, but when using should pay attention to viscosity and doping control, at the same time should pay attention to its water-soluble rate, such as speed.
dry powder putty uses a lot of organic additives, these materials together when stirring will introduce a large number of bubbles, directly into the putty products, in putty construction prone to fine holes, affecting the appearance of the material and the use of performance, so can be added desiccant to reduce the production of bubbles.
dry powder putty is a water-based material, after construction, if in humid air conditions, prone to mold and other phenomena, thus affecting the use of function, so adding a certain amount of dry powder preservatives in putty powder is to ensure long-term use of the material basis, preservative selection and doping should be determined according to the putty system and the use of the site.
Putty water resistance directly affects the quality of putty products, glue powder can provide good bonding performance, but water resistance is generally poor, the cost is too high when using large quantities, so white cement, gray calcium powder is a single-group water-resistant putty important ingredients, is to give high bonding strength, high water resistance and cost-effective important raw materials. First of all, gray calcium powder in the air reaction to form a hard calcium carbonate high-strength waterproof layer, cement and water chemical reaction to form a high-strength gel material, so a certain amount of white cement, gray calcium powder can fully ensure that putty bonding strength and water resistance to meet the standard requirements, but doping should be determined by a detailed ratio test. Hydroxypropyl methyl cellulose has good dispersion and cold water solubility, providing good water preservation performance for putty, thus ensuring that putty is smooth and delicate during construction. But its main disadvantage is that when scraping the surface of the putty film local bubbles and produce fine holes, thus affecting the flatness of the putty layer, desiccant with its matching use can better make up for this defect, get a good flat effect.
external wall environment on the characteristics of putty requirements
the outer wall directly in the atmospheric environment, will be directly affected by the natural climate, so the performance requirements of materials coated on the outer wall surface is naturally very strict, which is mainly reflected in the physical and physical properties of putty film requirements. First of all, putty film should be able to adhere firmly to the wall grass, and after a certain amount of water erosion, freeze-thaw cycle damage and other circumstances do not fall off, which requires putty has a higher stretch, bond strength and water resistance; Secondly, the water absorption rate of the outer wall putty is low, and the volume expansion after absorbing water should be as small as possible, so as not to have a greater destructive effect on the coating film; Third, the outer wall putty film should have a certain dynamic crack resistance, that is, after the emergence of fine cracks in the grass, putty film does not crack with it, but can form a bridge effect on the crack. Obviously, all of these performance characteristics need to be achieved by selecting the right film-forming substance and a reasonable formulation. In addition, as a widely used product, the outer wall putty also needs to have good batch coating, wearability and other necessary construction performance.
Flexive outer-wall putty
flexible putty to eliminate cracks
flexible outer-wall putty and elastic outer-wall putty belong to the same type, is its putty film can produce significant deformation of putty, this kind of putty can mask the wall appeared in the fine cracks. Cement mortar, slurry surface of the wall grass, because dry shrink often appear on the surface width, depth of fine cracks, such cracks also have "hot expansion cold shrink" and "wet expansion dry shrink" dynamic change nature, if the use of ordinary putty, when the wall cracks or cracks in the size of the change, putty film can not produce corresponding deformation, there may be cracks, and will be permeable to the coating film. The use of flexible or elastic putty is one of the effective ways to solve this problem.
The principle of using flexible putty to solve the dynamic change of cracks is mainly because the flexible putty film can produce deformation and absorb the stress applied to the putty film and coating film due to the contraction of the mortar layer (or slurry layer), thus ensuring that the putty layer does not crack.
Flexible outer wall putty formula
(1) formula design ideas
putty can actually be regarded as a high viscosity coating, but this high viscosity is not completely thickened by thickener results, but to have a relatively high solid content. Therefore, putty formula design ideas and coatings are not essentially different. Its special features are: First, to be able to putty into a paste, with a scraper to provoke not to hang, that is, with a high viscosity of high tentacles; Second, when the extrusion strength and fracture elongation of putty are required to be high, the pigment volume concentration of putty should be lower than or close to its critical pigment volume concentration. Third, flexible or elastic putty use of film-forming substances must be elastic building emulsion, not the use of glassy temperature higher ordinary building emulsion; Fourth, taking into account the batch scratching problem of putty, we should pay attention to the use of water-preserving thickeners.
(2) the basic formula of two-part flexible putty
the external wall flexible putty needs to be flexible, for stretch strength, bond strength, water resistance also has higher requirements, so it is advisable to use two-part method preparation, so that cement can be used to improve water resistance of putty film, while avoiding paste products can not use cement and powdered products of the high price of latex powder contradictions.
(3) Formula Description:
polymeric parts are the key materials that determine the flexibility of putty membranes. When a certain amount can not be reached, putty film crack resistance indicators can not meet the standard requirements. The role of deboist in the formulation is very important to prevent the production of pores in putty film; Due to the addition of water to the polymer emulsion, the concentration of the original anti-mold agent in the emulsion is reduced, so it needs to be replenished to ensure that the liquid storage will not mold. The addition of cellulose ether to the powder can reduce the mold-proof requirements of the liquid parts. Preparation of flexible putty requires the use of glassy lower temperature polymer emulsion, its minimum film-forming temperature is low, so the liquid does not need to be added as a membrane additive, but in order to ensure the stability of low-temperature storage of liquid, still need to use antifreeze (freeze-thaw stabilizer).
Generally speaking, the inner and outer wall putty is best not to mix, the inner wall putty can not meet the performance requirements of the outer wall putty, the external wall putty environmental protection performance will be worse than the inner wall putty.