The function and application of cellulose ether in environmental protection building materials
Cellulose ether is a non-ionic semi-synthetic polymer, water-soluble and solvent two, in different industries caused by the role is different, such as in the chemical building materials, it has a composite effect:
① water-retaining agent
② thickening agent
③ leveling
④ film forming
⑤ binder;
In the PVC industry, it is an emulsifier, dispersant; In the pharmaceutical industry, it is a kind of binder and slow release skeleton material, because cellulose has a variety of composite effects, so it is the most widely used field. Below I focus on the use of cellulose ether in environmental protection building materials and the role.
1. latex paint
In the latex paint line, to choose hydroxyethyl cellulose, the general specification of viscosity is RT3000-50000cps, the reference dosage is generally 1.5‰-2‰. The main role of hydroxyethyl in latex paint is to thicken, prevent pigment gelation, contribute to the dispersion of pigment, latex, stability, and can improve the viscosity of components, contribute to the leveling performance of construction: Hydroxyethyl cellulose is easy to use, can be dissolved in both cold and hot water, and is not affected by PH value, can be used between PH value 2 and 12, the use of the following three methods:
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I. Directly add:
For this method, hydroxyethyl cellulose delayed type — hydroxyethyl cellulose with dissolution time of more than 30 minutes should be selected. The procedure is as follows: (1) to have high should cut blender container and quantitative pure water (2) people began to slow stirring continuously, at the same time slowly add hydroxyethyl evenly to the solution of (3) continue to stir until all wet granular materials (4) to join other additives and alkaline additives (5) stir until completely dissolved all hydroxyethyl, add the other components of formula, grinding to the finished product.
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ⅱ. Equipped with mother liquor:
This method can choose the fast – soluble cellulose, and has mildew – proof effect. The advantage of this method is to have bigger flexibility, can join emulsioni paint directly in, make up a method is same as ①–④ step is same.
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ⅲ, with porridge for use:
Since organic solvents are poor solvents (insoluble) for hydroxyethyl, they can be used to prepare porridge. The most commonly used organic solvents are the organic liquids in latex paint formulations, such as ethylene glycol, propylene glycol and film forming agents (such as diethylene glycol butyl acetate), the porridge hydroxyethyl cellulose can be directly added to the paint, after adding, continue to stir until completely dissolved.
2. scraping the wall putty
At present, China is in most of the city water resistance, resistance to swab of environmental protection putty has been basically taken seriously by people, in a few years ago, because the putty made of building glue radiates formaldehyde gas damage to people’s health, building glue is made of polyvinyl alcohol and formaldehyde acetal reaction. So this material is gradually eliminated by people, and the replacement of this material is cellulose ether series of products, that is to say, the development of environmental protection building materials, cellulose is the only kind of material at present.
In water resistant putty is divided into dry powder putty and putty paste two kinds, the two kinds of putty generally choose modified methyl cellulose and hydroxypropyl methyl two kinds, viscosity specification is generally in 3000-60000cps between the most appropriate, in the main role of cellulose in putty is water retention, bonding, lubrication, etc..
Because the putty formula of each manufacturer is not the same, some are gray calcium, light calcium, white cement, some are gypsum powder, gray calcium, light calcium, etc., so the specification viscosity and infiltration amount of cellulose of the two formulas are not the same, the general amount of adding is 2‰-3‰ or so.
In blow wall be bored with child construction, the wall base has certain absorbent (brick wall of the bibulous rate was 13%, the concrete is 3-5%), coupled with the evaporation of the outside world, so if be bored with child water loss too fast, would lead to crack or the phenomenon such as pollen, so that the strength of the putty weakened, therefore, after joining cellulose ether will solve this problem. But the quality of filling material, especially the quality of gray calcium is also extremely important. Because of the high viscosity of cellulose, it also enhances the buoyancy of putty, and avoids the phenomenon of flow hanging in construction, and it is more comfortable and labor-saving after scraping.
3. concrete mortar
In concrete mortar, really achieve ultimate strength, must make the cement hydration reaction completely, especially in the summer, in the construction of the concrete mortar water loss too fast, completely hydrated measures on curing water, this method is a waste of water resource and inconvenient operation, the key is just on the surface, water and hydration is still not completely, so the ways to solve this problem, In mortar concrete generally choose to add hydroxypropyl methyl cellulose or methyl cellulose, viscosity specifications between 20000–60000cps, adding amount of 2‰–3‰ or so, water retention rate can be increased to more than 85%, in mortar concrete use method for dry powder evenly mixed after adding water.
4. paint gypsum, bonding gypsum, caulking gypsum
With the rapid development of the construction industry, people’s demand for new building materials is also increasing day by day, because of the increase of people’s awareness of environmental protection and the continuous improvement of construction efficiency, cementitious material gypsum products have been rapid development. At present the commonnest gesso goods has stucco gesso, caking gesso, set gesso, tile caking agent to wait.
Plaster is a kind of excellent quality of interior wall and roof plastering material, with it to wipe the wall is delicate and smooth, do not drop powder, and the base bond firmly, no cracking off phenomenon, and has fire prevention function; Adhesive gypsum is a new type of building light board adhesive, gypsum as the base material, plus a variety of additives and made of sticky material, it is suitable for all kinds of inorganic building wall materials bonding, with non-toxic, tasteless, early strength and fast setting, bonding is a building board, block construction supporting materials; Gypsum seam filling agent is gypsum plate between the gap filling material and wall, crack repair filling.
These gypsum products have a range of different functions, in addition to gypsum and related fillers to play a role, the key issue is the added cellulose ether additives play a leading role. As a result of gesso cent does not have water gesso and the cent of half water gesso, different gesso is different to the performance effect of the product, increase so thick, protect water, slow coagulate the quality that decides gesso building materials. The common problem of these materials is hollow drum cracking, initial strength is not up to, to solve this problem, is to choose the type of cellulose and retarding agent compound use method problem, in this respect, the general choice of methyl or hydroxypropyl methyl 30000–60000cps, adding amount is 1.5‰–2‰ between, the focus of cellulose is water retention and retarding lubrication.
However, in this to rely on cellulose ether as retarder is not up to, must also add citric acid retarder after mixed use will not affect the initial strength.
Water retention rate generally refers to the amount of natural water loss in the absence of external water absorption. If the wall is dry, the base surface absorbs water and natural evaporation makes the material lose water too fast, and there will also be empty drum and cracking phenomenon.
This method of use is to mix dry powder, if the preparation of solution can refer to the preparation method of solution.
5. insulation mortar
Thermal insulation mortar is a new type of interior wall thermal insulation material in north China. It is a wall material synthesized by thermal insulation material, mortar and binder. In this material, cellulose plays a key role in bonding and increasing strength. Generally, methyl cellulose with high viscosity (about 10000eps) is selected, and the dosage is generally between 2‰ and 3‰. The method of use is dry powder mixing.
6. interface agent
The interface agent is HPMC20000cps, the tile binder is more than 60000cps, and the interface agent is mainly used as thickener, which can improve the tensile strength and arrow strength