INTRODUCTION

This invention relates to a water-based paint stripper. In particular, but not exclusively, the invention relates to a water-based roof paint stripper (WBRPS) composition, a method of applying the composition to a metal roof; method of manufacturing the composition, and kit thereof.

BACKGROUND TO THE INVENTION

According to a machine translation of RU2204577C2, this patent relates to a composition for removing paint coatings. The composition includes sodium hydroxide, quicklime, chalk, water, soda ash and polyethylene oxide.

US1 ,589,219 relates to a paint and varnish removing compound consisting of a non-inflammable paste containing lye, sal soda, hydrated magnesium sulphate, corn starch, and calcium carbide. Calcium carbide is added to the solution just prior to application thereby liberating acetylene gas and producing hydrated lime.

These compositions are not available for removing paint from a metal roof.

It is an object of this invention to provide an improved water-based roof paint stripper composition and method of stripping paint/coatings from a metal roof.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention there is provided an aqueous composition for stripping paint from a surface, wherein the composition includes:

Sodium carbonate about 2% to 4% w/w;

Calcium hydroxide about 5% to 9% w/w;

Starch about 1 % to 3% w/w;

Sodium hydroxide about 10% to 14% w/w, and the balance is water; wherein: the composition has a viscosity of about 30 000 to 40 000 centipoise (cPs).

Preferably, the starch is corn starch.

The composition may comprise: about 3% w/w sodium carbonate; about 7% w/w calcium hydroxide; about 2% w/w starch; and about 12% w/w sodium hydroxide, about 76% w/w water; wherein the composition has a viscosity of about 33 000 to 36 000 cPs.

Typically, the composition comprises about 6 kg sodium carbonate; about 14 kg calcium hydroxide; about 5 kg starch; about 25 kg sodium hydroxide; and about 160 I of water, wherein the composition has a viscosity of about 33 000 to 36 000 cPs.

The composition may include a retardant, preferably the retardant is raw glycerol.

The composition may comprise: about 3% w/w sodium carbonate; about 7% w/w calcium hydroxide; about 2% w/w starch; about 12% w/w sodium hydroxide; about 1% w/w raw glycerol; and about 75% w/w water; wherein the composition has a viscosity of about 34 600 cPs.

Typically, the composition comprises: about 6 kg sodium carbonate; about 14 kg calcium hydroxide; about 5 kg starch; about 25 kg sodium hydroxide; about 2.5 kg raw glycerol; and about 160 I water; wherein the composition has a viscosity of about 34 600 cPs.

The composition may include zinc phosphate.

The composition may comprise: about 3% w/w sodium carbonate; about 7% w/w calcium hydroxide; about 2% w/w starch; about 12% w/w sodium hydroxide; about 1% w/w raw glycerol; about 1% w/w zinc phosphate about 74% w/w water; wherein the composition has a viscosity of about 34 600 cPs.

Typically, the composition comprises: about 6 kg sodium carbonate; about 14 kg calcium hydroxide; about 5 kg starch; about 25 kg sodium hydroxide; about 2.5 kg raw glycerol; about 1 .8 kg w/w zinc phosphate; about 160 I water; wherein the composition has a viscosity of about 34 600 cPs.

In accordance with another embodiment of the invention there is provided a method of manufacturing a paint stripper composition including the steps of:

(a) providing a mixture of water and sodium carbonate;

(b) blending the mixture of step (a) to produce a blended mixture;

(c) adding calcium hydroxide to the blended mixture of step (b), and blending the mixture to produce a blended mixture of water, sodium carbonate and calcium hydroxide;

(d) optionally adding a retardant and/or zinc phosphate to the blended mixture of step (c), and blending the mixture further;

(e) adding starch to the blended mixture of step (c) or (d), and blending the mixture even further;

(f) leaving the blended mixture of step (e) open to allow the mixture to settle; and

(g) breaking the mixture of step (f), and re-blending the mixture to produce a smooth, consistent composition.

Preferably, steps (b) to (d) further include blending the mixtures using an electric mixer at a speed of about 700 revolutions per minute (rpm) for about to 5 minutes. Preferably, step (e) further includes blending the mixture using an electric mixer at a speed of about 700 rpm for about 10 minutes.

Preferably, the blended mixture of step (f) is left open for about 48 to 72 hours depending on ambient temperature to allow the mixture to settle.

In accordance with another embodiment of the invention, there is provided a kit including:

(a) the composition defined above; and

(b) a cover.

Preferably, the cover is a low density polyethylene sheet.

In yet another embodiment of the invention, there is provided a method of applying the composition as defined above to a surface, wherein the method comprises of the steps of:

(a) providing a composition to be applied to a surface;

(b) applying the composition of step (a) to the surface;

(c) immediately covering the surface containing the composition with a cover;

(d) after about 24 hours to 48 hours, partially removing the cover from an area of the covered surface, and scraping the uncovered surface to remove paint/paint coatings from the surface;

(e) repeating step (d) until the entire covered surface is uncovered, and paint coatings are scraped off from the whole surface; and

(f) washing the paint coatings of step (d) or (e) with water and/or with a cleaning apparatus and detergent. Preferably, the composition is applied in 1 ,5-meter strips at a time and covered at once.

Typically, the surface is a metal roof.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail, by way of examples only, with reference to the accompanying drawings in which:

Figure 1 shows a method of covering a surface containing a paint stripper composition in accordance with the invention;

Figure 2 shows a method of removing the cover and scraping the surface of Figure 1 in accordance with another embodiment of the invention;

Figure 3 shows a method of washing the scraped surface of Figure 2 in accordance with another embodiment of the invention; and

Figure 4 shows personal protective equipment (PPE) required when applying the methods of Figure 1 to 3.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

As used herein, throughout this specification, the singular forms “a”, “an” and “the” include the plural form, unless the context clearly indicates otherwise.

The terminology and phraseology used herein is for the purpose of description and should not be regarded as limiting. The use of the terms “comprising”, “containing”, “having”, “including”, and variations thereof used herein, are meant to encompass the items listed thereafter, and equivalents thereof as well as additional items.

In this specification, all amounts are expressed as percentage weight in relation to the total weight (% w/w) of the composition.

This invention relates to a composition for stripping or removing paint/paint coatings from a surface. The composition includes:

Sodium carbonate about 2% to 4% w/w;

Calcium hydroxide about 5% to 9% w/w;

Starch about 1 % to 3% w/w;

Sodium hydroxide about 10% to 14% w/w, and the balance is water, and wherein the composition has a viscosity of about 30 000 to 40 000 cPs. Optionally, the composition may include about 0% to 2% w/w retardant, preferably about 1 % retardant. The retardant is raw glycerol.

The composition may comprise: about 3% w/w sodium carbonate; about 7% w/w calcium hydroxide; about 2% w/w starch; about 12% w/w sodium hydroxide; and about 76% w/w water; wherein the composition has a viscosity of about 33 000 to 36 000 cPs.

Preferably, the composition comprises: about 6 kg sodium carbonate; about 14 kg calcium hydroxide; about 5 kg starch; about 25 kg sodium hydroxide; and about 160 I of water, wherein the composition has a viscosity of about 33 000 to 36 000 cPs.

The composition may comprise: about 3% w/w sodium carbonate; about 7% w/w calcium hydroxide; about 2% w/w starch; about 12% w/w sodium hydroxide; about 1% w/w raw glycerol; and about 75% w/w water; wherein the composition has a viscosity of about 34 600 cPs.

Preferably, the composition comprises: about 6 kg sodium carbonate; about 14 kg calcium hydroxide; about 5 kg starch; about 25 kg sodium hydroxide; about 2.5 kg raw glycerol; and about 160 I water; wherein the composition has a viscosity of about 34 600 cPs.

The composition may include about 0% to 1% w/w zinc phosphate.

The composition may comprise: about 3% w/w sodium carbonate; about 7% w/w calcium hydroxide; about 2% w/w starch; about 12% w/w sodium hydroxide; about 1% w/w raw glycerol; about 1% w/w zinc phosphate about 74% w/w water; and wherein the composition has a viscosity of about 34 600 cPs.

Preferably, the composition comprises about 6 kg sodium carbonate; about 14 kg calcium hydroxide; about 5 kg starch; about 25 kg sodium hydroxide; about 2.5 kg raw glycerol; about 1 .8 kg w/w zinc phosphate; about 160 I water; and wherein the composition has a viscosity of about 34 600 cPs. Surprisingly, it has been found that the addition of a retardant such as raw glycerol during the manufacturing of the composition reduces the time it takes the composition to dry once it is applied to a surface.

The surface can be any surface for which paint/paint coating has previously been applied, including a metal, wood, concrete, and asbestos. Preferably the surface is a metal roof.

The calcium hydroxide used is preferably brown/white hydrated lime. The starch is preferably, corn starch (food grade), and sodium hydroxide is caustic soda (NaOH 99%).

The composition for stripping paint from a surface is manufactured using the following steps:

(a) providing a mixture of water and sodium carbonate;

(b) blending the mixture of step (a) to produce a blended mixture;

(c) adding calcium hydroxide to the blended mixture of step (b), and blending the mixture to produce a blended mixture of water, sodium carbonate and calcium hydroxide;

(d) optionally adding a retardant and/or zinc phosphate to the blended mixture of step (c), and blending the mixture further;

(e) adding starch to the blended mixture of step (c) or (d), and blending the mixture even further;

(f) leaving the blended mixture of step (e) open to allow the mixture to settle; and

(g) breaking the mixture of step (f), and re-blending the mixture to produce a smooth, consistent composition.

Steps (b) to (d) further include blending the mixtures using an electric mixer at a speed of about 700 rpm for about 5 minutes. In step (e) the mixture is blended using an electric mixer at a speed of about 700 rpm for about 10 minutes.

Preferably, the blended mixture of step (f) is left open for about 48 to 72 hours depending on ambient temperature to allow the mixture to settle. After 48 or 72 hours depending on ambient temperature, break the settled product and mix the product again using an electric mixer on medium speed to produce a smooth consistent composition.

The composition for stripping paint from a metal roof may also be supplied as a kit, comprising of the said composition, and a cover.

Preferably, the cover is a low density polyethylene sheet. The low density polyethylene sheet may be washed and re-used.

The paint stripper composition is applied to a surface using the following steps:

(a) providing a composition to be applied to a surface;

(b) applying the composition of step (a) to the surface;

(c) immediately covering the surface containing the composition with a cover (as shown in Figure 1 );

(d) after about 24 hours to 48 hours, partially removing the cover from an area of the covered surface, and scraping the uncovered surface to remove paint/paint coatings from the surface (as shown in Figure 2) ;

(e) repeating step (d) until the entire covered surface is uncovered, and paint coatings are scraped off from the whole surface; and

(f) washing the paint coatings of step (d) or (e) with water and/or with a cleaning apparatus and detergent (as shown in Figure 3). Preferably, the composition is applied in 1 ,5-meter strips at a time, and covered at once.

The method of manufacturing a paint stripper composition, and applying the paint stripper composition to a metal roof, will now be further described more fully with reference to the below non-limiting embodiment:

Example 1 : Manufacturing method for a paint stripper composition

Components

Per 180-liter Batch

• 160 1 Clean Water

• 6 kg Soda ash dense

• 14 kg Brown/white hydrated lime (Calcium hydroxide)

• 5 kg Corn starch (food grade)

• 25 kg Caustic soda (NaOH 99%)

• 2.5 kg Raw Glycerol (retardant)

Step by step mixing method

1 . Put water into 200lt drum

2. Add soda ash slowly to drum

3. Put electric mixer on low speed and mix for 5 minutes

4. Add brown or white hydrated lime and mix for 5 minutes on low speed

5. Add caustic soda slowly and mix for 5 minutes on low speed

6. Add raw glycerol and/or zinc phosphate and mix at low speed

7. Add corn starch and mix for 10 minutes low speed 8. Leave mixture open to stand for 48 to 72 hours to settle depending on ambient temperature

9. Break product up with flat wooden paddle/rafter (76x50mm) then mix again with electric mixer on medium speed until smooth consistency

10. Decan product into plastic 5LT/20LT pales

Step by step application method of the paint stripper composition

1. Make sure all persons working with the paint stripper composition have proper personal protective equipment (see Figure 4 for the recommended personal protective equipment).

2. Always have neutralizer (White Vinegar) on hand for spillages or when product gets in contact with skin or eyes.

3. Always make sure that the correct safety precautions are adhered to on dangerous workplaces.

4. Pre-cut cover sheets (LDPE Low density polyethylene 60 microns) to correct size in order to cover the WB Roof Paint Stripper.

5. Make sure all movable assets have been moved away from direct working area in advance and cover all plants and valuables that can’t be moved away.

6. Always work in the opposite direction to which the WB Roof Paint Stripper is applied and apply with soft nylon broom to ±1 .2lt per m ² and do not walk on the applied area (it will be slippery). The WB Roof Paint Stripper must be applied in 1 ,5m strips at a time and covered at once.

7. Use normal cement bricks to anchor the cover sheeting on roof that it doesn’t blow around or get affected by weather elements.

8. Repeat the process with an overlap of 200mm and 200mm over ridging to the desired roof area being stripped. 9. Two teams of two persons must apply the full system. First one (1 ) person applies the product and the other three (3) close product with cover sheets and anchor with normal cement bricks.

10. Particularly important to make sure sheeting is anchored properly.

1 1. After 24 hours do a test and open a corner and scrape with scraper to see if paint is coming off, if not leave another 24 hours and repeat test. Generally, after (3) days all the layers of old roof coatings will have softened and will be easy to remove.

12. Remove cover sheets and bricks and dispose of safely alternatively it may be washed and re-used.

13. Hydro wash with HP Cleaner 2500-3000psi with rotating nozzle to remove the old roof coatings and then rinse with clean water.

14. If the building has gutters rinse and clean the gutters with clean water.

15. Once hydro washing of roof area has been completed. Wash roof with general purpose cleaner and rinse all other areas that have been affected, such as plants and paving if necessary.

Units which are used in this specification and which are not in accordance with the metric system may be converted to the metric system with the aid of the following conversion factors: 1 centipoise (cP) = 1 x 10’ ³ Pa.s, and 1 psi = 6,895 x 10 ³ Pa .

Advantages of the water based roof paint stripper composition and/or method

The entire WB Roof Paint Stripper system saves time, labour and is in the long run more cost effective. • For example, a 500m ² roof will take approximately five (5) days to apply the complete WB Roof Paint Stripper process to get old flacking paint back to bare metal. Where normally it would take 1 .5 to 2 weeks to mechanically sand, grind and scrap any old paint coatings off surfaces. This older method leaves ±70% of the old coatings stay and the paint coatings that have been left behind has been weakened by friction in this process.

• Anti-corrosive primers have been designed to apply to metal and for corrosion but not designed to apply on old flaking roof coatings.

• With WB Roof Paint Stripper applications, you don’t have failed coatings on top of failed coatings that has been built up over time.

• The WB Roof Paint Stripper system is more effective as it is always going back to bare metal, rust treat where necessary, prime and overcoat with roof coat on specification will make any roof coating lifespan last longer.

• Many manufacturers will back out of a claim that may arise due to failure of roof coatings. It’s always the preparation that is not done properly to manufacturers specifications that causes roof coating failures. Going back to bare metal is always the best choice for any coating to adhere to substrate.

• Corrosion creeps under old roof coatings when the application is not done according to manufacturer specifications and is not always visible once the roof has been re-painted. By using WB Roof Paint Stripper and taking the roof back to bare metal you can prevent comebacks due to corrosion resurfacing through the new system.