Exterior Emulsion Paint Formulation
Exterior wall planar latex paint formulation design ideas
I. Preamble:
Compared with the interior wall latex paint, the exterior wall latex paint is more complicated in terms of performance and formula composition. Exterior wall latex paint is usually color paint, so it requires better weather resistance, water resistance, light and color retention.
Dispersants, wetting agents and thickeners are indispensable additives in exterior paints. Conjugate thickeners have lipophilic and hydrophilic groups, similar to the role of “polymeric surfactants”, conjugate thickeners and surfactants not only produce a similar behavior, but also interact with the same or similar components. Currently widely used polymer coating dispersant is actually a special type of surfactant. Dispersants and binding thickeners in the common aqueous medium and in the pigment and emulsion particles on the surface of the competition adsorption, there is a complex relationship between the two competing, whether their matching combination is reasonable directly affect the performance of the emulsion paint.
Second, the choice of dispersant.
1, the dispersant used in emulsion paint should be chosen as the main water-resistant dispersant with coupling effect and compounded with some conventional dispersants.
2, proven by practice: in the formulation of exterior wall emulsion paint, we recommend the use of water-resistant dispersant GR-2500 as the main dispersant and GR-5040 as a supplement.
a) GR-2500 dispersing ability, at the same time with the system of excellent compatibility, will not affect the coating gloss, is an ammonium salt of acrylic acid copolymer, to avoid the drawbacks of sodium salt salting out; itself has a low-foaming, and can effectively wet the surface of the hydrophobic pigment, this dispersant even if you add too much also will not have a bad effect on the system. GR-2500 is a hydrophobic nonionic copolymer dispersant with excellent water resistance, which can also be used as a film-forming material; it stabilizes the pigment filler by spatial resistance of effective anchoring groups, and has a low HLB value, which can effectively solve the problem of floating color and blooming.
b)GR-5040 is acrylic acid copolymerized sodium salt, which plays the role of rapid viscosity reduction and enhanced dispersion.
c) GR-109 is a non-ionic wetting agent, low HLB value, can effectively solve the floating color and bloom.
3, we use 6.0 ‰ -8.0 ‰ of GR-2500 in the formula and compound 2.0 ‰ of GR-5040 and 2.0 ‰ of GR-109 in the external wall, high PVC latex paint formulations, color, water resistance, rain and late viscosity storage stability is excellent.
Third, the choice of filler.
1, the gloss of the film, air permeability and weather resistance requirements are different, the exterior wall emulsion paint formulations generally control the filler in the total amount of paint ranging from 20% to 45% (exterior paint formulations solid content should be higher than 45%).
2, pigment:
a) white pigment with rutile titanium dioxide, should be adjusted according to the color of the color paint color shades of titanium dioxide additive amount, dark paint titanium dioxide should be added less or not add, generally add the amount of control in the range of 0%-5% (white paint generally add 8%-20%); not suitable to add anatase titanium dioxide and Lidl powder. Can also be made of titanium content of 1%, 15% of the basic paint for mutual adjustment, ordinary or special requirements of white paint can be based on the actual situation of a separate formula.
3、Filler:the body pigment with not too fine particle size is good, the particle is fine, the number of particles in each unit volume is big, and it is easy to see the phenomenon of chalking on the surface, which is in fact the result of the increase of the area between pigment and base material, and the result of the deterioration of weathering resistance. In addition, large particle size particles are not easy to move, will also reduce the floating color phenomenon, small particle size particles will help to improve the covering power of the film and feel, and reduce the tendency of precipitation.
a) Calcined kaolin: good covering properties, excellent suspension and moisture absorption, impact resistance. It is divided into washed and calcined type.
b) Mica powder: enhance the coating film, anti-pollution, anti-UV.
c) Wollastonite powder: partial dry covering power, good hardness, UV resistance.
d) In the formulation of high-performance exterior wall surface coating latex paint, we do not recommend the use of calcium carbonate, because it is easy to “white frost” on the surface of the coating film, and it is generally only used in the formulation of primer or middle coating latex paint. But the current formula is basically in use.
4, we generally do not use light calcium carbonate and talcum powder in the formulation of exterior latex paint. Special requirements of the formula can be considered discretionary use, because easy weathering, weathering is not good.
5, barium sulfate: barite powder and precipitated barium sulfate. It is less used because it is not easy to be dispersed. Because of its low oil absorption and part of the masking effect, weather resistance is also good, so in some formulations, discretionary use or compound use.
6, we use 8% rutile titanium dioxide, 10% calcined kaolin, 15% wollastonite powder, 12% heavy calcium carbonate in the high PVC exterior wall formula, 17% rutile titanium dioxide, 5% mica powder, 5% kaolin, 10% wollastonite powder (accounting for the total amount of paint) in the low PVC white exterior wall paint formulations, the performance of the excellent. Color mixing base paint formula is otherwise required.
Fourth, the choice of thickener.
1, in the exterior wall emulsion paint, we recommend not to use HEC thickener or a small amount of HEC. experiments have proved that: with HEC thickening of paint film densification is not as good as with HASE type and HEUR type of thickening of paint film, so the water resistance of the film will be reduced; the other on the HEC will lead to rollers or brush marks, stubble, etc., the fullness of the paint film is not high, easy to spatter in the process of construction.
2. We recommend GR-60, GR-935, GR-8W and GR-2020 for exterior emulsion paint.
a) GR-60 anionic alkali activated acrylic thixotropic thickener, low dosage, strong anti-settling effect, improve the storage stability of the finished paint, so as to solve the problem of delamination and sedimentation.
b) GR-935 anionic hydrophobic alkali activated acrylic thickening agent, low dosage, unique internal cross-linking mechanism makes the product in the static state (shear rate is zero) has a very high yield value, the water phase, emulsion, pigment and filler have become a bridge linking, which can help to solve the problem of water splitting of the paint and floating color bloom.
c) GR-8W meets the requirements of zero and low VOC environment protection, and has certain thixotropy, which can effectively improve the viscosity of the paint in low and medium shear rate; GR-8W has excellent color spreading and very low color difference value (△E), which can effectively solve the problem of stomer viscosity (KU) decline caused by adding color paste, and it is especially suitable for use in color paints.
c) GR-2020 has excellent thickening and leveling effect, with high and medium shear and high shear viscosity, providing excellent can opening effect and dry film fullness, which can improve the splashing during the construction process to the minimum.
3, color paint, the addition of color paste can cause the viscosity of the paint to reduce, especially HEUR thickener is the most sensitive to color paste, so can not use HEUR as a basic paint thickener alone, even in the semi-gloss and high-gloss latex paints should be added to the appropriate amount of HASE thickener, we recommend GR-935 or GR-615 with GR-8W and GR-2020 thickeners used. We recommend GR-935 or GR-615 with GR-8W and GR-2020 thickener.
4, we in the high, medium and low PVC exterior formulations according to the situation (optional) or the use of 0.5 ‰ -1 ‰ of HEC cellulose (optional or not), 1 ‰ GR-HV2 or GRB, 1 ‰ -2 ‰ GR-60, 2 ‰ -3 ‰ GR-935 and 2 ‰ -3 ‰ GR -8W, 2‰-3‰GR-2020 (accounting for the total amount of paint), adjust the formula to make the paint low, medium and high shear viscosity is more balanced. 48 hours later, the viscosity tends to stabilize.
Fifth, the choice of synthetic emulsion.
1, from the film gloss, air permeability and weather resistance and other considerations, the emulsion content is generally controlled in the total amount of paint from 20% to 60%.
2, exterior latex paint formulations we generally rarely recommend the use of phenylpropylene emulsion, in the weathering requirements are not too high occasions (such as primer and paint formulations), we recommend that the excellent performance of phenylpropylene and pure propylene emulsion with the use of.
3, exterior wall emulsion paint weathering and stain resistance has been the most concerned, and these two properties are mainly provided by the synthetic emulsion, so we are in the choice of emulsion, glass transition temperature (Tg) and the minimum film temperature (MFT) balance between the must be considered.
4. The thickening efficiency of HEUR-type thickeners depends on the nature and concentration of the dispersed particles (i.e., synthetic emulsions) in the formulation. For cellulose-based thickeners formulations, different emulsions can be used interchangeably, whereas for HEUR-type thickeners, the viscosity changes extensively by switching to different emulsions. We have observed in our experiments that in some hydrophobic emulsion systems (e.g., Baddeford’s RS-2204 emulsion, the amount of thickener is much less than in hydrophilic emulsion systems).
5、We use Bardolph Group’s phenylpropylene emulsion RS-998A (10% of the total amount of paint) and Bardolph’s pure C emulsion RS-2806 (10% of the total amount of paint) mixed in the middle and high PVC formulations of the exterior wall, and Bardolph’s pure C emulsion RS-2806 (40% of the total amount of paint) is used in the exterior wall’s low PVC formulations, and, of course, it can be chosen according to the specific situation: Individual or compound use RS-998A, RS-2204, exterior wall king, RS-2806, etc., the comprehensive performance of the manufactured coatings are very excellent.
Sixth: the problem of thinking.
1, weatherability is one of the most important performance of exterior latex paint, but due to the long testing time, expensive testing equipment, so far there is no good testing method, so it is the most difficult for paint manufacturers to grasp, the most prone to quality problems of the indicators. The causes of poor weatherability are often the following.
a) The chemical structure and crystal type of the pigment are not suitable;
b) The particle size of the pigment is too small;
c) Poor weatherability of the emulsion in the coating;
d) The particle size volume concentration of the pigment is too large;
e) Use of unstable emulsions;
f) Using poor quality pigment filler.
2, affect the film texture, exterior latex color paint in the filler thicker can improve weathering performance, the reason is that coarse filler surface area is small, less base material required, its critical PVC is larger, so allow the paint can be used in a high PVC system still does not exceed the CPVC, the coating film is still very good weather resistance.
3, water resistance for exterior latex paint and weathering is equally important, whether high PVC or low PVC exterior.
a) First of all, we should choose water-resistant dispersant, GR-2500 not only improves water resistance due to the introduction of hydrophobic groups, but also improves the coupling between organic and inorganic pigments and fillers, and the spatial site resistance improves the storage stability of pigments and fillers.
b) The thickener has the property similar to surfactant, so the emulsion paint made is more or less water-sensitive, which is mainly manifested in the reduction of wet adhesion and the greater tendency of blistering when the paint film meets the rain in the early stage, which may be partly attributed to the tendency of the thickener to gather on the interface of the substrate in the film formation. General selection principle (principle of competitive adsorption): GR-2500 as the main system, with GR-8W + GR-935; if GR-5040 as the main system, with GR-935 + GR-8W (the former as the main thickener).
c) HASE and ASE thickeners are anionic, more water-sensitive than non-ionic, which restricts their application in exterior paints, especially in the chalking of the old paint film. So we recommend in the formulation of exterior paint to make HEUR class (such as GR-8W and GR-2020) thickener, HEUR belongs to the non-ionic thickener, and thickened to the same viscosity dosage than the HASE class dosage is less, and HEUR class is the thickening agent in the water resistance of the film the smallest impact of a class.
Seven, the exterior wall emulsion paint reference formula: unit / g
1、Exterior wall high PVC latex paint (dispersant with GR-2500 and GR-5040, thickening system with GR-935 and GR-8W)
Material name
High-speed dispersion for 10 minutes, over sanding, washing machine and into the back, slow down the mixing speed, add the following:
2. Formulation constants.
Dry film thickness: 35uM Theoretical density of paint: 1.41KG/L Painted area: 10.69M2/KG
Mass solids: 55.57% Volumetric solids: 37.41% Face to base ratio: 4.28:1
PVC: 57.75% Contrast ratio: 0.95 Scrub resistance: >5000 times
Water resistance: 96 hours without exception Alkali resistance: 48 hours without exception PH value: 8.8
Flowability: excellent Open: no delamination, good stirring lag
3. Viscosity and thermal storage stability measurements: 60rpm 6rpm stomer.
60rpm 6rpm stomer
Overnight: 3200cps 13500cps 96KU
50℃/15days: 3600cps 14000cps 97KU
50℃/30days: 4000cps 14800cps 98KU
4、Low PVC emulsion paint for exterior wall (GR-2500 and GR-5040 for dispersant, GR-8W and GR-2020 for thickening system)
Material name
5、 Formulation constant
Dry film thickness: 35uM Theoretical density of paint: 1.31KG/L Painting area: 12.20M2/KG
Mass solids: 56.71% Volumetric solids: 42.72% Face to base ratio: 1.88:1
PVC: 34.68% Contrast ratio: 0.95 Scrub resistance: >10000 times
Water resistance: 96 hours without exception Alkali resistance: 48 hours without exception PH value: 8.8
Flowability: excellent Open: no delamination, good stirring lag
6. Viscosity and thermal storage stability measurements: 60rpm 6rpm stomer.
60rpm 6rpm stomer
Overnight: 2800cps 12000cps 93KU
50℃/15days: 3000cps 13000cps 94KU
50℃/30days: 3500cps 13800cps 95KU
7、Use of HEUR polyurethane (PU) thickener.
A. HEUR thickener is mainly bonded with the emulsion, so firstly, you should choose the synthetic emulsion with strong bonding effect with HEUR thickener.
B. HEUR thickener itself has high viscosity, when adding it should be diluted with alcohol solvent (we recommend Texanol), in order to facilitate the addition and reduce unnecessary waste.
