2 августа, 2015 
Malyar These acrylic resins are essentially based on pure acrylic monomers or blends of these with styrene monomer. They are applied by brush, roller or airless spray. The last method allows the application of thick coatings over large areas, though heavily textured coatings will require more specialised equipment such as spatter, or plaster guns. The heavy film builds applied require the use of thixotropic or fibrous additives to impart the shear thinning behaviour necessary to eliminate sagging of the wet coating.
A typical starting point formulation for a textured masonry finish is given below:
WHITE HIGH BUILD TEXTURED MASONRY FINISH
|
Synocryl 874S (Cray Valley) |
36.70 |
|
Cereclor 54 (Zeneca) |
4.93 |
|
Thixotrope — Hydrogenated castor oil |
2.30 |
|
Rutile titanium Dioxide |
13.42 |
|
Calcium carbonate |
12.00 |
|
20 micron talc |
8.40 |
|
Micronised mica |
1.26 |
|
Polyethylene fibre FPE 920T (Sparkford Chemicals) |
1.68 |
|
Low density texture filler EUP13 (Johns Manville) |
2.50 |
|
Shellsol A |
16.81 |
|
Total |
100.00 |
|
Volume solids |
45% |
|
PVC |
44% |
|
VOCg/1 |
480 |
The formulation is based on a thermoplastic acrylic plasticised with chlorinated paraffin, Cereclor 54, (3:1 wt/wt).
Synocryl 874S is a hard TPA copolymer, 40%nvc in Shellsol A.
The plasticiser increases the solids content of the coating, but also makes the white film prone to yellowing on exterior exposure.
In addition to the usual pigments and extenders, the formulation contains a fibrous polyethylene filler which reduces cracking and helps prevent sagging.
A hydrogenated castor oil wax imparts thixotropy. Texture is achieved through the use of a low density filler which is a heat treated mineral with high bulking value.
Опубликовано в рубрике 