Research on the application of water-based bottom all-in-one paint based on old wall renovation

There are still some old building exterior walls decorated with old mosaics and veneer materials in our country, which not only affects the appearance, but also has the hidden danger of falling off
.
Therefore, refurbishing these old walls is an urgent problem to be solved
.
Water-based exterior wall coatings are the mainstream of many exterior wall decoration materials.
Generally, water-based exterior wall coatings include base treatment, putty layer, primer and topcoat.
Multi-layer construction process coating online coatingol.
com
.
For the renovation of old mosaics and veneer materials, paint finishes are used for renovation.
Usually the first step of construction is to remove the original veneer, and then carry out the conventional construction process, which is time-consuming and time-consuming.
Increase costs
.

In addition, ordinary exterior wall coatings are not waterproof, and rainwater is likely to penetrate the wall, causing the paint film to blistering, fading, and falling powder
.
It is difficult to realize the construction directly on the surface of the wall tiles that need to be refurbished
.
Because the surface of the tile is dense and smooth, the bonding strength of ordinary exterior wall coatings is low, and it is difficult to directly attach to the tile surface
.
Therefore, the requirements for exterior wall coatings are even higher
.
Therefore, the research and development of a water-based bottom surface all-in-one coating that can be applied to the surface of ordinary putty, cement mortar and ceramic tiles with excellent performance, not only reduces labor costs, but also has excellent waterproof functions.
The construction process and construction cost of refurbishing old walls Shows a huge advantage in
.

The designed and developed water-based bottom surface all-in-one paint is a composite system of organic liquid material (organic resin) and inorganic powder material.
It combines the advantages of organic and inorganic materials.
It is a valuable research direction for architectural coatings
.
After repeated testing, the water-based bottom surface all-in-one coating not only meets the performance requirements of exterior wall coatings (primer and topcoat), but also conforms to the trend of exterior wall coatings to multi-functional development
.

1 Experimental part

1.

The main raw materials of the water-based bottom surface all-in-one coating are shown in Table 1
.

Sand-milling dispersion mixing machine (SFJ-400 type); washing resistance tester (JTX-Ⅲ type); reflectivity tester (C84-Ⅲ type); Stormer viscometer (STM-V type), Shanghai Modern Environment Engineering Ltd; Desktop xenon lamp aging chamber (BGD 865 type), Guangzhou standard laboratory equipment supplies Ltd.
Baghdad; high and low temperature (TL-100 type), the Suzhou Creek environmental test equipment Co.
, Ltd.
Chi
.

1.

See Table 2 for the basic formulation of the water-based bottom all-in-one coating
.

1.

First, fix the container on the high-speed dispersing machine, add water, wetting agent and hydroxyethyl cellulose to the dispersing container, control the speed at 600～800r/min, disperse for 15min to dissolve the cellulose completely, and then add the dispersion in sequence Disperse for 10 minutes, then add emulsion, film-forming aids and pH adjuster for 10 minutes, and finally add thickener for 10 minutes to prepare the A component slurry
.
Then, the A-component slurry and the integrated decoration powder are uniformly mixed according to the mass ratio of 1:1, and then the water-based bottom surface all-in-one paint is prepared
.

1.

See Table 3 for the main performance testing standards of the water-based bottom surface all-in-one coating
.

2 Results and discussion

2.

Table 4 shows the viscosity and pH measurement results of the A-component slurry and the water-based bottom coating
.
It can be seen from Table 4 that the viscosity of the A-component slurry is relatively low.
After the two components are fully mixed, the viscosity will increase.
Therefore, in order to meet the different construction requirements of customers, such as spraying or roller coating, the viscosity of the A-component slurry can be adjusted.
Viscosity is controlled
.
In addition, the pH of the A-component slurry is relatively low, and the pH rises slightly after preparing the water-based bottom surface all-in-one coating.
This is because the hydration product generated by the B-component powder encountering the A-component slurry contains alkaline substances.
Lead to
.
Therefore, in the actual production process, it is not advisable to adjust the pH of the A-component slurry too high.
The B-component powder must be stored in a cool and dry place to avoid being affected by moisture or contact with water
.

2.

The drawing method was used to test the bond strength on three different substrates: cement base, uneven tile surface and smooth glazed tile surface.
The results are shown in Figure 1
.

Figure 1 The bonding strength test results of cement base (a), non-flat tile surface (b) and flat glazed tile surface (c)

It can be seen from the figure that the bond strengths measured on different substrates are different.
Among them, the bond strength on the cement base layer is the lowest.
The untreated bond strength reaches 1.
36 MPa, and the cement base layer is damaged.
The cement base layer has high bonding strength, which reflects the bonding strength of the cement base layer itself from a certain angle
.
After being treated with alkali, water immersion and wet base, the bonding strength is different.
The analysis reason is that the water content and pH of the substrate have a greater impact on the tested bonding strength
.
The water content of the cement base layer is different, which causes the cement base layer to absorb the moisture in the coating differently, which in turn leads to the difference in the bonding strength test results
.

In addition, the bonding strength on the flat glazed tile surface is the highest, and the untreated bonding strength reaches 7.
69MPa, which destroys the tile surface.
This indicates that the bonding strength between the water-based bottom surface all-in-one paint and the glazed tile is greater than or Equal to the bonding strength of the glazed tile itself
.
In addition, from the bond strength data after different treatments on three different substrates, it can be found that the bond strengths after immersion treatment and alkali treatment are higher than those without treatment
.

The bonding strength of non-flat glazed tiles is lower than that of flat glazed tiles.
There are two reasons for analysis.
On the one hand, the flatness of glazed tiles greatly affects the bonding area of ​​the specimen, and the same amount of adhesive is used.
In the case of, the flatter the base layer, the larger the bonding area, which helps to reduce or avoid the separation phenomenon or hidden dangers between the water-based bottom surface all-in-one paint and the adhesive, as shown in the picture of the wet base layer in Figure 1(b), part The water-based bottom surface all-in-one paint still adheres to the surface of the uneven glazed tile, that is, there is a phenomenon of separation between the adhesive and the paint interface.
The bond strength tested under such conditions is usually lower than the real bond strength, so , To avoid the separation between the adhesive and the coating, can improve the bond strength (unreal bond strength)
.
On the other hand, due to the unevenness of the non-flat glazed tiles, the water-based bottom surface all-in-one paint has poor film thickness uniformity during the construction process, and the convex surface of the non-flat glazed tiles will have a thinner paint film.
Phenomenon
.
On the contrary, a thicker paint film is bound to appear on the concave surface
.
The uniformity of the paint film thickness has a greater impact on the bond strength test.
Within a certain range, with the increase of the paint film thickness, the bond strength between the paint film and the base layer will increase, so the water-based bottom coating is equivalent In the case of dosage, the same area of ​​non-flat glazed tiles and flat glazed tiles are constructed.
The thickness of the raised part of the non-flat glazed tiles is thinner than that of the flat glazed tiles, so the bonding strength will also appear Small phenomenon
.

In summary, the water-based bottom surface all-in-one coating has extremely strong bonding strength and adhesion on the cement base layer and the surface of the glazed tile under various treatment conditions
.

2.

Figure 2 shows the water permeability test results of the water-based bottom surface all-in-one coating
.
It can be seen from the figure that the water permeability of the water-based bottom surface all-in-one coating is only 0.
1mL, which meets the standard requirements of exterior wall coatings
.
Water permeability is an effective method to test the compactness of paint film.
The low water permeability indicates that the paint film is denser.
It also reflects that the paint film has a certain degree of waterproof function, which is beneficial to improve the protection of the wall
.

2.
4 Analysis of resistance to washing

See Figure 3 for the scrub resistance test results of the water-based bottom surface all-in-one coating
.
It can be seen from the figure that after 12,000 washing resistance tests, the coating film of the water-based bottom surface all-in-one coating did not appear to be damaged, exposed, or blistered
.
This shows that the water-based bottom surface all-in-one coating has excellent film-forming properties and excellent scrub resistance, which is largely determined by its good adhesion and water permeability
.

2.
5 Main technical index test

The main technical index test results of the water-based bottom surface all-in-one coating are shown in Table 5
.

Remarks: The bond strength test data comes from the cement base
.

It can be seen from Table 5 that the anti-alkalinity and salting-out resistance of the water-based bottom surface all-in-one coating are higher than the standard requirements of the exterior wall paint primer, which shows that the water-based bottom surface all-in-one coating has a very strong film Sealing and high compactness
.
In addition, the water resistance test of the water-based bottom surface all-in-one coating has reached 144h without any abnormality in the paint film, which is much higher than the index requirement, which shows that the paint film has excellent water resistance
.
The impermeability pressure reaches 0.
8MPa.
The stronger the impermeability pressure of a material, the more prominent the impermeability and the better the waterproof ability
.
In addition, the tensile strength and elongation at break of the water-based bottom surface all-in-one coating have reached the performance indicators
.
From a formulation perspective, the proper ratio between organic and inorganic base materials plays an important role
.
It is worth noting that the flexibility reaches 66.
2mm, which is 33 times the standard requirement.
This shows that the water-based bottom surface all-in-one coating has excellent flexibility and can adapt to slight vibration and displacement of the building structure
.
The calculated flexural ratio (the ratio of compressive strength to flexural strength) is 2.
75, which once again shows that the water-based bottom surface all-in-one coating has excellent flexibility
.
In a word, the water-based bottom surface all-in-one coating not only meets the standard requirements of exterior wall paint primer and topcoat, but also has a high waterproof function
.

3 conclusion

The water-based bottom surface all-in-one coating is developed for the current general exterior wall coatings are not waterproof, the renovation construction on the old ceramic tile surface has the disadvantages of low bonding strength and adhesion, complex construction technology, and high construction cost.