Wood filler composition

Abstract

This invention relates to a wood filler composition and more particularly, but not exclusively, to a wood filler composition that includes a water-based acrylic polymer emulsion combined with calcium sulfate. The composition may be either a one-component or a two-component formulation. The one- component composition of the wood filler consists of 21.5% water-based acrylic polymer; 76.4% calcium sulphate; 0.3% plasticizer; 0.8% mineral oxide; and 1 % protein water solution. The two-component composition of the wood filler consists of a water-based acrylic polymer liquid including a plasticizer, combined with a calcium sulphate powder containing mineral oxide, mixed in a ratio of 1 :3 - 1 :4.

Description

[0001] WOOD FILLER COMPOSITION

[0002] FIELD OF THE INVENTION

[0003] This invention relates to a wood filler composition and more particularly, but not exclusively, to a wood filler composition that includes a water-based acrylic polymer emulsion combined with calcium sulfate.

[0004] BACKGROUND

[0005] Wood fillers are widely utilized in the woodworking industry to address gaps, cracks, and imperfections in wooden surfaces. Currently, two main categories of wood fillers dominate the market: solvent-based and water-based formulations.

[0006] Solvent-based wood fillers, while effective in repairing wood surfaces, come with significant drawbacks. The presence of volatile organic compounds in these formulations results in the release of toxic fumes and a strong odour during manufacture and application. This necessitates adequate ventilation or the use of protective gear. Additionally, the flammability of solvent-based wood fillers poses a fire hazard during storage and application.

[0007] On the other hand, water-based wood fillers, though environmentally friendly and low in toxicity, have their own set of challenges. Their susceptibility to moisture makes them prone to swelling or disintegration in damp conditions, jeopardising their structural integrity. These fillers also tend to dry slowly compared to their solvent-based counterparts, causing inconvenience for time-sensitive projects. Moreover, they may raise the wood grain upon application, requiring additional sanding for a smooth finish. Despite their eco- friendly nature, water-based wood fillers are less suitable for outdoor use or environments with fluctuating humidity.

[0008] Both solvent-based and water-based wood fillers exhibit durability issues, especially in high-traffic or exterior applications. They are susceptible to wear, cracking, or breaking over time, necessitating periodic maintenance or reapplication. Moreover, these fillers can undergo dimensional changes with variations in temperature and humidity.

[0009] Existing wood fillers, though effective for small repairs, prove inadequate for larger or deeper repairs, lacking the structural integrity of the surrounding wood. This structural weakness is exacerbated when the applied filler undergoes sanding, drilling, or planing.

[0010] Furthermore, achieving a perfect colour match with the surrounding wood remains a persistent challenge with existing wood fillers. Despite claims of stainability or paintability, replicating the natural colour and grain of the wood often results in a noticeable contrast after application. OBJECT OF THE INVENTION

[0011] It is an object of this invention to provide a wood filler composition which, at least partially, alleviates the above-mentioned difficulties.

[0012] SUMMARY OF THE INVENTION

[0013] In accordance with a first aspect of the invention a one-component wood filler composition is provided. This composition includes a water-based acrylic polymer and calcium sulphate.

[0014] The water-based acrylic polymer of the one-component composition contains 1 % - 70%, and preferably, 45% - 50% solids by weight.

[0015] The water-based acrylic polymer is furthermore an emulsion, being a single emulsion or a combination of two or more emulsions.

[0016] The calcium sulphate of the one-component composition contains 10% - 90% final blend solids by weight.

[0017] The calcium sulphate may be of different grades, including calcium sulphate dihydrate (gypsum), calcium sulphate hemihydrate (plaster of Paris), and calcium sulphate anhydrous. Furthermore, the preferred form of the calcium sulphate hemihydrate is the alpha form thereof (CaSO4 >2H2O). The one-component composition may further contain a plasticizer in the range of 0.1 % - 10% solids by weight. The plasticizer is selected, but not limited to the phthalates group, such as dioctyl phthalate. The plasticizer can also be an adipate, sebacate, trimellitate, epoxy, phosphate, or other bio-based plasticizer.

[0018] Additionally, the one-component composition may contain a mineral oxide in the range of 0.01 % to 5% solids by weight.

[0019] Furthermore, the one-component composition may contain a protein water solution in the range of 0.01% - 10% solids of the total blend by weight.

[0020] Preferably, the one-component composition consists of 21.5% water-based acrylic polymer; 76.4% calcium sulphate; 0.3% plasticizer; 0.8% mineral oxide; and 1 % protein water solution.

[0021] The one-component composition may further include an inhibitor, selected from the group including proteins, polycarboxylates, polyphosphates, polymers of carboxylic acid, or sodium or ammonium salts.

[0022] The one-component composition may be a putty or a paste.

[0023] Other additives such as surfactants, thickeners, pH adjusters, wetting agents, extenders such as fly ash, nutshell flour, perlite, and hollow glass spheres may be added to the one-component wood filler composition to adjust certain characteristics and parameters thereof.

[0024] In accordance with a second aspect of the invention a two-component wood filler composition is provided. This composition includes a water-based acrylic polymer liquid component and a calcium sulphate powder component.

[0025] The liquid component may further contain a plasticizer in the range of 0.1 % - 10% solids by weight. The plasticizer is selected, but not limited to the phthalates group, such as dioctyl phthalate. The plasticizer can also be an adipate, sebacate, trimellitate, epoxy, phosphate, or other bio-based plasticizer.

[0026] The powder component may include a mineral oxide in the range of 0.01 % to 5% solids by weight.

[0027] The liquid component is in a mixture with the powder component in a ratio range of 1 :0.5 - 1 :10, and preferably, in a ratio range of 1 :3 - 1:4.

[0028] The mixture of the liquid component and the powder component is of a smooth consistency.

[0029] The water-based acrylic polymer of the two-component compositions contains 1 % - 70%, and preferably, 45% - 50% solids by weight. It is further provided for the water-based acrylic polymer to be an emulsion, being a single emulsion or a combination of two or more emulsions.

[0030] The calcium sulphate of the two-component composition may be of different grades, including calcium sulphate dihydrate (gypsum), calcium sulphate hemihydrate (plaster of Paris), and calcium sulphate anhydrous. Furthermore, the preferred form of the calcium sulphate hemihydrate is the alpha form thereof (CaSO^F ).

[0031] It is further provided for the calcium sulphate of the two-component composition to be in the range of 10% - 90% solids by weight.

[0032] The two-component composition may further include an inhibitor, selected from the group including proteins, polycarboxylates, polyphosphates, polymers of carboxylic acid, or sodium or ammonium salts.

[0033] An activator, such as calcium sulphate, aluminium sulphate, ferric sulphate, zinc sulphate or ferric chloride, may be employed before use of the two- component wood filler composition to accelerate the setting thereof.

[0034] Mineral oxides may be added to the two-component wood filler composition to adjust the colour thereof. The quantity of mineral oxide added to the two- component wood filler composition can range between 0.01 % to 5% of total blend by weight. Other additives such as surfactants, thickeners, pH adjusters, wetting agents, extenders such as fly ash, nutshell flour, perlite, and hollow glass spheres may be added to the one-component wood filler composition to adjust certain characteristics and parameters thereof.

[0035] These and other features of the invention are described in more detail below.

[0036] DETAILED DESCRIPTION OF THE INVENTION

[0037] The following description is provided as illustrating the principles of the invention and is not intended to limit the scope of the invention.

[0038] In accordance with a first aspect of the invention a one-component wood filler is provided.

[0039] A ready to use wood filler putty is prepared with the following composition: 21.5% water-based acrylic polymer; 76.4% calcium sulphate; 0.3% plasticizer; 0.8% mineral oxide; and 1 % protein water solution.

[0040] The water-based acrylic polymer is a water-based acrylic resin containing 45% to 50%, solids by weight.

[0041] The calcium sulphate used is the alpha form of calcium sulphate hemihydrate (CaSO4%H2O). In accordance with a second aspect of the invention a two-component wood filler is provided. This composition includes a water-based acrylic polymer component and a calcium sulphate powder component.

[0042] A biobased plasticizer, is added to the water-based acrylic polymer component in the range of 0.1 % to 10% solids by weight.

[0043] A mineral oxide is added to the calcium sulphate powder component in the range of 0.01 % to 5% solids by weight.

[0044] The liquid component and powder component are mixed, under high shear, in a ratio range of 1 :05 to 1 :10. The mixture is blended until a smooth consistency is achieved.

[0045] The water-based acrylic polymer of the liquid component is a water-based acrylic resin and contains 45% to 50%, solid by weight.

[0046] The plasticizer composition is added to the acrylic polymer at approximately 1 % level by weight. The plasticizer composition works by increasing the plasticity and spreadability of the final blend for better application.

[0047] The calcium sulphate used is the alpha form of calcium sulfate hemihydrate (CaSO4 / 2H2O). During the mixing with the water-based acrylic polymer liquid component, the calcium sulphate hemihydrate rehydrates to form calcium sulfate dihydrate. Calcium sulfate hemihydrate has a relatively short setting time, which is advantageous when used as a wood filler.

[0048] It is envisaged that the wood filler described herein will be convenient to use as it is designed for user-friendliness, incorporating a water-based acrylic emulsion combined with inorganic minerals to yield a high-performance product. Distinguished by its non-shrinking and non-cracking properties, this composition is well-suited for both interior and exterior applications. It exhibits exceptional adhesion to wooden surfaces, allowing for versatile use, including drilling and screwing. Notably, the wood filler is fast setting, enhancing efficiency in various woodworking processes.

[0049] Key advantages of this wood filler include its solvent-free formulation, rendering it non-flammable, odour-free, and more environmentally friendly. Additionally, it boasts lower toxicity compared to many existing wood fillers, aligning with sustainability standards. The components and manufacturing process contribute to its cost-effectiveness, offering an economical alternative to current wood fillers without compromising on performance.

[0050] It will be appreciated by those skilled in the art that many other embodiments of the invention are possible without departing from the scope thereof.

[0051] The acrylic polymer can be a single emulsion or a combination of two or more emulsions. Combining emulsions allows for the adjustment of the final properties of the two-component wood filler, including hardness, flexibility, and spreadability.

[0052] A biobased plasticizer, can be added to the wood filler blend in the range of 0.5% to 10% by weight, to soften the wood filler blend, making it more spreadable.

[0053] Inhibitors, such as proteins, polycarboxylates, polyphosphates, and polymers of carboxylic acid, sodium or ammonium salts, can be added to the wood filler blend to increase the pot life and shelf life thereof.

[0054] An activator, such as calcium sulphate, aluminium sulphate, ferric sulphate, zinc sulphate, or ferric chloride, can be employed before use of the wood filler putty to accelerate the setting thereof.

[0055] Mineral oxides can be added to the wood filler putty to adjust the colour thereof. The quantity of mineral oxide added to the two-component wood filler can range between 0.1% to 5% by weight.

[0056] Other additives such as surfactants, thickeners, pH adjusters, wetting agents, extenders such as fly ash, nutshell flour, perlite, and hollow glass spheres can be added to the wood filler to adjust certain characteristics thereof.

Claims

CLAIMS1. A wood filler comprising a one-component composition consisting of a water-based acrylic polymer and calcium sulphate.

2. A wood filler as claimed in claim 1 in which the water-based acrylic polymer contains 1 % - 70% solids by weight.

3. A wood filler as claimed in claim 1 in which the water-based acrylic polymer is 45% - 50% solids by weight.

4. A wood filler as claimed in any one of the preceding claims in which the water-based acrylic polymer is an emulsion.

5. A wood filler as claimed in claim 4 in which the emulsion is a single emulsion or a combination of two or more emulsions.

6. A wood filler as claimed in any one of the preceding claims in which the calcium sulphate component comprises 10% - 90% of the final blend solids by weight.

7. A wood filler as claimed in any of the preceding claims in which the calcium sulphate is of different grades, including calcium sulphate dihydrate (gypsum), calcium sulphate hemihydrate (plaster of Paris), and calcium sulphate anhydrous.

8. A wood filler as claimed in claim 7 in which the calcium sulphate is the alpha form of the calcium sulphate hemihydrate (CaSO^F ).

9. A wood filler as claimed in any one of the preceding claims in which the one-component composition includes a plasticizer in the range of 0.1 % - 10% solids by weight.

10. A wood filler as claimed in claim 9 in which the plasticizer is a biobased plasticizer.

11. A wood filler as claimed in any one of the preceding claims in which the one-component composition includes a mineral oxide in the range of 0.01 % to 5% solids by weight.

12. A wood filler as claimed in any one of the preceding claims in which the one-component composition contains a protein water solution of 0.01 % - 5% solids of the total blend by weight.

13. A wood filler as claimed in any one of the preceding claims in which the one-component composition consists of 21.5% water-based acrylic polymer; 76.4% calcium sulphate; 0.3% plasticizer; 0.8% mineral oxide; and 1 % protein water solution.

14. A wood filler as claimed in any one of the preceding claims in which the one-component composition includes an inhibitor.

15. A wood filler as claimed in claim 14 in which the inhibitor is selected from the group including proteins, polycarboxylates, polyphosphates, polymers of carboxylic acid, or sodium or ammonium salts.

16. A wood filler as claimed in any of the preceding claims in which the one- component composition is a putty or a paste.

17. A wood filler comprising a two-component composition consisting of a water-based acrylic polymer liquid component and a calcium sulphate powder component.

18. A wood filler as claimed in claim 17 in which the liquid component includes a plasticizer in the range of 0.1 % - 10% solids by weight.

19. A wood filler as claimed in claim 18 in which the plasticizer is a biobased plasticizer.

20. A wood filler as claimed in any one of claims 17 - 19 in which the powder component includes a mineral oxide in the range of 0.01% to 5% solids by weight.

21. A wood filler as claimed in any one of claims 17 - 20 in which the liquid component is in a mixture with the powder component in a ratio range of 1 :0.5 - 1 :10.

22. A wood filler as claimed in any one of claims 17 - 20 in which the liquid component is in a mixture with the powder in a ratio range of 1 :3 - 1 :4.

23. A wood filler as claimed in any one of claims 17 - 22 in which the liquid and powder mixture is of a smooth consistency.

24. A wood filler as claimed in any one of claims 17 - 23 in which the waterbased acrylic polymer contains 1 % - 70% solids by weight.

25. A wood filler as claimed in any one of claims 17 - 23 in which the waterbased acrylic polymer is 45% - 50% solids by weight.

26. A wood filler as claimed in any one of claims 17 - 25 in which the waterbased acrylic polymer is an emulsion.

27. A wood filler as claimed in claim 26 in which the emulsion is a single emulsion or a combination of two or more emulsions.

28. A wood filler as claimed in any one of claims 17 - 27 in which the calcium sulphate is of different grades, including calcium sulphatedihydrate (gypsum), calcium sulphate hemihydrate (plaster of Paris) and calcium sulphate anhydrous.

29. A wood filler as claimed in claim 28 in which the calcium sulphate is the alpha form of the calcium sulphate hemihydrate (CaSO^F ).

30. A wood filler as claimed in any one of claims 28 - 29 in which the calcium sulphate in the range of 10% - 90% solids by weight.

31. A wood filler as claimed in any one of claims 17 - 30 in which the two- component composition includes an inhibitor.

32. A wood filler as claimed in claim 31 in which the inhibitor is selected from the group including proteins, polycarboxylates, polyphosphates, polymers of carboxylic acid, or sodium or ammonium salts.