Description:
PREAMBLE TO THE DESCRIPTION:

The following specification describes this invention.

FIELD OF THE INVENTION
The present invention relates to a primer composition. Specifically, the invention relates to a liquid primer composition exhibiting superior adhesion to surfaces while emitting low volatile organic compound (VOC).

BACKGROUND OF THE INVENTION
Preparing the walls for painting is always a tedious job and involves use of multiple coats of plaster of Paris (POP) followed by painting in multiple coats to obtain the desired finish. This is not only expensive, but also time consuming since there is a drying time required between coats. Skim coating is a texturing technique used to make a wall surface smooth. There are two types of skim coats - acrylic polymer based skim coats and cement based skim coats. Marketed skim coats are commonly acrylic polymer based which are applied to plastered walls to achieve optimal wall surface smoothness which are then ready for further application of paints/distempers.

The adhesive capacity of paint is over POP or a skim coat is a function of a primer applied over plastered surface or POP/skim coat. The adhesive property of the paint over plastered surface or over POP/skim coat is improved by way of application of a layer of primer. The primer is usually applied directly over a plastered surface or applied over surface of POP/skim coat.

Currently available primers, either oil-based or polymer (acrylic) based, which has a tendency to be brittle over a period of time after being applied. The substrate to which the primer is applied (plastered surface or POP/skim coat) flexes as temperature changes, whereas the primer, when hardened, does not flex or move in the same way.

Conventional acrylic based primers comprise of inorganic compounds such as ammonia, which lead to emission of undesirable bad odor/smell that also impacts health of user applying the primer. The pH of the acrylic based primers is in the range of pH 8-9. Known acrylic based primers are alkaline (pH>7) and it is important they remain so to maintain product performance. A drop in the pH level of the product will result in poor run off properties, and may change color and viscosity. Some acrylic primers have a very high volatile organic compound (VOC) and emits a pungent smell. The adhesive strength of known acrylic based primers are also low which results in powdering/chalking property at surface.

Thus, there exists a need for a composition for use as a primer that have low volatile organic compounds, enhanced durability and adhesion will resist hardening and stay flexible, thereby allowing the primer to move, expand and flex with the substrate to which it is applied.

SUMMARY OF THE INVENTION
The object of the invention is achieved a liquid primer composition which maintains the primer in liquid form, increase durability, adhesion with volatile organic compound (VOC). The formulation of liquid primer disclosed in proposed invention is based on cement which plays the role of an inorganic hydraulic binder providing strength and rigidity to the primer. The liquid primer composition includes 0.1 -5% of white cement, 8-20% of Acrylic emulsion or styrene acrylic emulsion based binder and 0.1-1 % of thickener in 20-40% of diluent or water.

In an embodiment, the composition further includes 0.1- 0.5 % of an accelerator; 0.1-1 % of preservatives; 0.1-1 % of a dispersing agent; 0.1-1 % of solubiliser; 0.1-1 % of wetting agent; 0.1-0.5 % of defoamer; 40-50 % of two mineral filler; 1-5 % of pozzolanic material; 1-6 % of an extender and 0.5-5 % of a smoothing agent or their combination to maintain the primer in liquid form.

In an embodiment, sodium aluminate is act as accelerator for cement to shorten the setting time.
In an embodiment, the preservative includes biocide and fungicide.

In an embodiment, Oratan 1288 act as dispersing agent to prevent sedimentation of particles.

In an embodiment, diethylene glycol act as solubiliser in water based primer and increases the coverage of primer.

In an embodiment, Triton X 405 act as wetting agent for better adherence of the primer particles to each other.

In an embodiment, TEGO Foamex 1488 act as deformer to achieve even coating and eliminates foam during primer application.

In an embodiment, thickeners are selected from HEC 250 HBR and Acrysol DR130 improve levelling, and prevent sedimentation of the filler and increase the viscosity of a primer.

In an embodiment, the mineral filler is selected from the group consisting of dolomite, calcite, talc, hydrated lime or a mixture thereof. Further, the weight percentage of calcite/dolomite is 33.2 % and talc is 2.5% in water based primer.

In an embodiment, pozzolanic material is preferably clay, comprising calcined kaolin which improves physical durability of the primer film.

In an embodiment, the binder includes Primal MC 76 based on Acrylic/styrene acrylic emulsion.

In an embodiment, extenders are preferably titanium dioxide and talk. Titanium dioxide pigment is a fine white powder, provides maximum whiteness and opacity.

In an embodiment, smoothing agent is an epoxy compound, preferably Epotech to improve stability and reduces water sensitivity of primer.

DETAILED DESCRIPTION OF THE EMBODIMENTS
The invention summarized above and defined by the enumerated claims may be better understood by referring to the following description, which should be read in conjunction with the accompanying claims. This description of an embodiment, set out below to enable one to build and use an implementation of the invention, is not intended to limit the invention, but to serve as a particular example thereof. Those skilled in the art should appreciate that they may readily use the conception and specific embodiments disclosed as a basis for modifying or designing other methods and systems for carrying out the same purposes of the present invention.

It is to be noted that, as used in the specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a composition containing “a compound” includes a mixture of two or more compounds. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.

The expression of various quantities in terms of “%” or “% w/w” means the percentage by weight, relative to the weight of the total solution or composition unless otherwise specified.

The term “primer” refers to a white cement-based polymer modified coating material used for building structures applied over different wall/surfaces to provide longer durability to paint.

The term “filler” used in reference are by products of cement industry which helps in controlling the final finish of the skim coat composition and is responsible for its unique natural bright & white color.

The term “volatile organic compounds” used in refers to organic chemical compounds that evaporate easily at room temperature.

The term “accelerator” as used herein refers to a compound that accelerates the cement hydration reaction with water.

The term “dispersing agent” as used herein refers to a compound ensure which viscosity stability & prevents sedimentation of particles in liquid primer.

The term “defoamer” as used herein refers to a chemical compound that reduces and hinders the formation of foam in industrial process liquids.

The term “thickener” as used herein refers compounds which can increase the viscosity of a liquid without substantially changing its other properties.

The term “smoothing agent” as used herein refers to a chemical compound that gives smoothing effect over surfaces.

The present invention provides a solution of cement based liquid wall primer white cement based liquid wall primer which applied as under coat over plastered wall as external primer & over putty wall surface as internal primer respectively. This cement based primer is an inorganic composite material in liquid form includes water, white cement, fillers, pozzolanic materials, accelerator, dispersing agent, wetting agent, defoamer, thickeners, extenders, binder, solubiliser, Biocides, Fungicide & water etc. Cement based liquid primer provides high durability and very low smell property by removing extra ammonia in the composition. The introduction of cement in primer give very good opacity and adhesive property. Water with cement, filler materials and other additives are added in predetermined proportion to protect wall surface & topcoat from normal/extreme weathering condition.

In an embodiment, the cementitious material is either white or grey cement, preferably white cement. The cementitious material plays the role of an inorganic hydraulic binder providing strength and rigidity to the primer. It helps in adherence of the primer once applied to the wall surface. The white cement in primer composition also imparts property of opacity to the primer.

Further, the liquid primer composition includes
a) 20-40 % of water;
b) 0.1 to 5% of white cement;
c) 1 to 5% of at least one pozzolanic material;
d) 0.1 to 0.5% of at least one accelerator;
e) 0.1-1% of at least one dispersing agent;
f) 0.1-1 % of at least two preservatives;
g) 0.1-1 % of at least one solubiliser
h) 0.1-1% of at least one wetting agent;
f) 0.1-3.0% of at least one defoamer;
g) 0.1-1% of at least two thickeners;
h) 40-50% of at least two mineral filler;
i) 1 to 6% of at least two extenders;
j) 8-20% of at least one binder;
k) 1-6% of at least one pigment; and
l) 0.5-5% of at least one smoothing agent

The accelerator is preferably sodiumaluminate. Sodium aluminate is known in the art as an accelerator for cement. Addition of sodium aluminate decreases and shorten the setting time of cement. Sodium aluminate performs cement hydration reaction in 15-20 minutes making the cement particles stable in liquid form for longer time period.

The dispersing agent is Oratan 1288. Dispersing agent is an essential component of most primer and coating formulations. Dispersing agent ensures viscosity stability and prevents sedimentation of particles.

Diethylene glycol act as solubilizer and imparts solvent properties to the primer and increases the coverage of primer. Di-ethylene glycol has good solvent properties with a low freezing point. Di-ethylene glycol imparts anti-freezing properties. Di-ethylene glycol easily mix water based primers for glossiness and smooth surface.

Further, the wetting agent used in the composition is Triton X 405. Wetting agent increases the spreading and penetrating properties of a liquid by lowering its surface tension resulting in better adherence of the primer particles to each other.

Defoamer rapidly eliminates foam during primer application and contributes to achieving even coatings that are free from defects.

In an embodiment, the defoamer is preferably TEGO Foamex 1488.

Additionally, thickeners are rheology modifiers which controls the rheological properties of the primer thereby preventing sagging during primer application. Thickeners adjust application thickness, improve levelling, and prevent sedimentation of the filler. Thickener increase the viscosity of a primer without substantially changing its properties.

In an embodiment, the thickener used in composition are preferably HEC 250 HBR and Acrysol DR130.

The mineral filler fills in all the pores of the walls and ceiling and provides a smooth and dry surface for painting and contributes to increasing the life of the painted surface.

In an embodiment, the mineral filler is selected from the group consisting of dolomite, calcite, talc, hydrated lime or a mixture thereof. The weight percentage of calcite/dolomite is 33.2 % and talc is 2.5% in water based primer.

Preferably, finer particles of calcite or dolomite having size of the calcite particles (8-15) microns is used. Due to the smooth finish, paint is not lost in uneven surface areas or undulations on the wall surface thereby decreasing the volume of primer is required for application, thereby further reducing the costs to the customer. Additionally, the high whiteness of the wall surface results in solar thermal infer-red reflectivity. It is a known phenomenon that products utilizing reflective technology are likely to have a longer service life because of the lower surface temperatures which in turn lessen the chemical and atmospheric degradation and also lessen the expansion and contraction. The lower surface temperature also keeps the interiors of the house cooler during hot days.

Furthermore, the pozzolanic material is preferably clay, comprising calcined kaolin. Calcined kaolin improves physical durability of the primer film and its burnish resistance.

The extenders are preferably titanium dioxide and talk. Titanium dioxide pigment is a fine white powder, when used in primers, it provides for maximum whiteness and opacity. It gives the primer high hiding power thereby enabling the ability of primer to mask or hide the substrate underneath.

The smoothing agent is an epoxy compound to improve stability and reduces water sensitivity of primer.

In an embodiment, the smoothing agent is preferably Epotech.

Lastly, the liquid primer composition further comprises of at least two preservatives as preservatives in the range of 0.1 to 0.6%, by weight of the composition. The preservatives are preferably biocide and fungicide. Preferably, the biocide is a selected from a group consisting of antimicrobial bactericide /fungicide. The preservatives prevent microbial contamination of the primer during storage and on the applied primer surface, thus increasing shelf life of primer. Said biocide is preferably chloromethyl isothyaazolinone and said fungicide is preferably Carbendazim.

The liquid primer of the present application is in liquid form, in spite of the presence of cement and water. It is well known to a person skilled in the art that, water and liquid when combined, which cures and harden into a solid form. However, the liquid primer of preset application maintains the primer in liquid form. The predetermined amount of white cement, Acrylic/styrene acrylic Binder and thickener provides desired technical results in form of, viscosity, pH, scrub resistance & film of primer in wall shown in table 1.

Ingredient Example-1
(without Cement ) Example-2
(with 5% Cement) Example-3
(with 10% Cement )
% Composition Water (Diluent) 28.7 30 31.6
White Cement (Binder) 0 5 10
Sodium Aluminate (Accelerator) 0.1 0.2 0.5
Kathon LXE (Biocide) 0.1 0.3 0.6
Rocima 363 (Fungicide) 0.1 0.3 0.6
Oratan 1288 (Dispersing Agent) 0.1 0.3 0.6
Diethylene Glycol (solubiliser) 0.1 0.1 1
Triton X 405 (Wetting agent) 0.1 0.1 1
TEGO Foamex 1488 (deformer) 0.1 2.5 0.5
HEC 250 HBR (Thickener) 0.1 0.3 0.6
Calcite/dolomite (Filler) 55 33.6 13
Talc (Filler) 3 2.5 5
Calcine kaolin (Clay) 3 4.5 7
TiO2 (Pigment) 1 3 6
Primal MC 76 (Binder)
(Acrylic/styrene acrylic emulsion) 8 15 17
Epotech (Smoothing agents) 0.5 2.3 5
Results Viscosity Low Viscosity Good Viscosity High Viscosity
pH 8.5-9.0 10-11 11-12
Scrub Resistance Poor Good Hard
Brashbility No Brush mark No Brush mark High brush mark
% Water Ratio 1:1 1:1 1:2
Settling @ 1:1 dilution after 24 hrs No Setting No Setting High Setting
Stability stable stable Unstable
Application on wall Smooth finish Smooth finish Matt finish
Film of primer in wall Very thin film Moderate film Matt film

The Table shows the comparison of prime composition with different amount of cement. In experiment no 1, when white cement is 0%, binder (Acrylic/styrene acrylic Binder) 8% & Thickener (HEC 250 HBR) 0.1 % of total composition. The desired technical results in form of, viscosity, pH, scrub resistance & film of primer in wall is found lower side value. Similarly, in application test, tool movement over wall/surface is found easy with thin film & less adhesion on wall by applicators/painters as compared to experiment-2 with 5% cement, binder (Acrylic/styrene acrylic emulsion) 15% & Thickener (HEC 250 HBR) 0.3 %.

In experiment no. 3, when white cement is 10%, binder (Acrylic/styrene acrylic Binder) 17% & Thickener (HEC 250 HBR) 0.6 % the desired technical results in form of, viscosity, pH, scrub resistance & film of primer in wall is found higher side value. Similarly, in application test, tool movement over wall/surface is found hard with thick film & hard adhesion on wall by applicators/painters as compared to experiment-2 with 5% cement, binder (Acrylic/styrene acrylic emulsion) 15% & Thickener (HEC 250 HBR) 0.3 % of total composition.

Hence, experiment 2 (with 5wt% of white cement) formulation provides moderate film with smooth finishing leads to good adhesion with wall, good viscosity and scrub resistance, and good stability with moderate pH value.

The liquid primer of the present application is maintained in a liquid form over a period of up to 3 years without degradation of the property.

Further, the liquid primer of present application does not include ammonia and hence does not emit volatile organic compounds during and after application. The pH of the liquid primer when applied on to a surface is in range of pH 10-11. The higher pH of the cement primer prevents discoloration & carbonation of paint over a long period of time.

Hence, cement based liquid primer improve the adhesion of liquid primer to a plastered & cementitious surface. The cement adhesion with cementitious material gives very high adhesion & durability to the surface as compared to non-cementitious acrylic based primer with plastered.
, Claims:I/We Claim:

1. A liquid primer composition comprising:
20-40 wt% of water;
0.1- 5 wt% of white cement;
8-20 wt% of a binder based on Acrylic emulsion or styrene acrylic emulsion; and
0.1-1 wt% of a thickener to maintain the primer in liquid form.

2. The liquid primer composition as claimed in claim 1, consists of at least:
0.1- 0.5 wt% of an accelerator;
0.1-1 wt% of one or more preservatives;
0.1-1 wt% of a dispersing agent;
0.1-1 wt% of a solubiliser;
0.1-1 wt% of a wetting agent;
0.1-3.0 wt% of a defoamer;
40-50 wt% of one or more mineral filler;
1-5 wt% of a pozzolanic material;
1-6 wt% of an extender and
0.5-5 wt% of a smoothing agent or combination thereof.

3. The liquid primer composition as claimed in claim 2, wherein the accelerator is sodium aluminate.

4. The liquid primer composition as claimed in claim 2, wherein the preservative is selected from biocide and fungicide.

5. The liquid primer composition as claimed in claim 2, wherein the dispersing agent is Oratan 1288, or the solubiliser is diethylene glycol,or the wetting agent is Triton X 405, or the combination thereof.

6. The liquid primer composition as claimed in claim 2, wherein the defoamer is TEGO Foamex 1488.

7. The liquid primer composition as claimed in claim 1, wherein the thickeners is selected from HEC 250 HBR, Acrysol DR130, or combination thereof, or the binder is Primal MC 76,or combination thereof.

8. The liquid primer composition as claimed in claim 2, wherein the mineral filler is selected from the group consisting of dolomite, calcite, talc, hydrated lime or a mixture thereof, wherein when the calcite/dolomite and/or talc are selected, the weight percentage of calcite/dolomite is 33.2 % and talc is 2.5% in water based primer.

9. The liquid primer composition as claimed in claim 2, wherein the pozzolanic material is clay, optionally including calcined kaolin

10. The liquid primer composition as claimed in claim 2, wherein the Titanium dioxide pigment is the extender, or the Epotech is the smoothing agent, or combination thereof.