Artificial stone comprising fused silica particles and method of making same

Abstract

An artificial stone and a method of making the artificial are disclosed. The artificial stone comprises: 6 to 16 wt.% acrylic thermoset resin; and 84 to 94% fused silica particles, wherein at least 40 wt.% of the fused silica particles are characterized by a particle size larger than 100 pm.

Description

ARTIFICIAL STONE COMPRISING FUSED SILICA PARTICLES AND METHOD OF MAKING SAME CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of Israeli Patent Application No. 318363, filed 13 January 2025, entitled “ARTIFICIAL STONE COMPRISING FUSED SILICA PARTICLES AND METHOD OF MAKING SAME”. The contents of the above application are all incorporated by reference as if fully set forth herein in its entirety.FIELD OF THE INVENTION

[0002] The present invention relates generally to slabs from artificial stones. More specifically, the present invention relates to artificial stones comprising fused silica particles.BACKGROUND OF THE INVENTION

[0003] Engineered stones (also known in the art as artificial stones, agglomerated stone or quartz slabs) are widely used as building materials e.g., for kitchen countertops, work surfaces, indoor and outdoor floors, wall claddings, dressing tables, bathtubs, washbowls, and interior articles. Artificial stone products are in great demand due to their ability to be manufactured in a wide variety of patterns and colors that cannot be found in nature and to show superior physical and mechanical performance when compared to natural stone.

[0004] These artificial stones are generally manufactured by mixing unsaturated polyester thermoset or acrylic thermoset compositions and aggregate and / or mineral, in a single layer. The unsaturated polyester thermoset compositions comprise an oligomeric chain comprised of saturated dicarboxylic acids or its anhydride as well as unsaturated dicarboxylic acid or anhydride. These two acids are reacted with one or more di-alcohols. The Resin mixture also comprises a reactive solvent, e.g., styrene, and cobalt-octoate as a curing process accelerator. The acrylic thermoset compositions comprise monomeric units selected from acrylate, methacrylate, and any derivative thereof and possibly a crosslinker. The aggregate and / or mineral can be any type of quartz, quartzite, feldspar, glass particles, clay, calcium carbonate, aluminum hydroxide, magnesium hydroxide, or any combination thereof. The mixture is substantially homogeneous across the entire slab.

[0005] Traditional materials often lack the necessary optical clarity and may contain components, such as, crystalline silica, linked to health risks such as silicosis.

[0006] The industry seeks materials that provide both aesthetic appeal and high performance without compromising safety. Certain materials introduce health risks due to the presence of harmful components, and other fillers do not provide the same optical clarity. There is a need for a material with an optimized combination of transparency, mechanical strength, and safety.SUMMARY OF THE INVENTION

[0007] Some aspects of the invention may be directed to an artificial stone comprising: between 6 to 18 wt.% acrylic thermoset resin; and between 82 to 94% fused silica particles. In some embodiments, the composition of the acrylic resin is selected to have a refractive index of between ± 0.25 of a refractive index of the fused silica. In some embodiments, the composition of the acrylic resin is selected to have a refractive index of between ± 0.15 of a refractive index of the fused silica.

[0008] In some embodiments, the fused silica particles comprise amorphous silica having at most 1 wt.% crystalline silica from the total weight of the fused silica. In some embodiments, the fused silica particles are characterized by a particle size of between 5 pm to 5 mm. In some embodiments, the acrylic resin comprises at least one of acrylic or methacrylic monomer. In some embodiments, the acrylic resin comprises at least one of: poly(methyl methacrylate) (PMMA), 2-ethylhexyl acrylate (2 -EHA), methacrylic acid (MAA), acrylic acid, urethane acrylate (UA)„ methyl methacrylate (MMA), 2-ethylhexyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl methacrylate, isobomyl acrylate, isobomyl methacrylate, and any derivative or combination thereof.

[0009] In some embodiments, the artificial stone further comprises a coupling agent. In some embodiments, the coupling agent is silane. In some embodiments, the weight percentage of the coupling agent is between 0.001 to 1 wt.%.

[0010] In some embodiments, the artificial stone further comprises between 0.001 to 1 wt.%. peroxide. In some embodiments, the artificial stone further comprises at least one additive. In some embodiments, the at least one additive is selected from, a pigment, UV reflector, UV stabilizer, a wetting agent, an antibacterial additive, an emulsifier, a mechanical toughener, a scratch resistance additive, and any combination thereof.

[0011] Some additional aspects of the invention may be directed to a method of making an artificial stone comprising: mixing between 6 to 18 wt.% acrylic resin; and between 82 to 94% fused silica particles to form a mixture; spreading the mixture; pressing the spread mixture; and hardening the pressed mixture.

[0012] In some embodiments, the method further comprises adding to the mixture between 0.001 to 1 wt.%. coupling agent. In some embodiments, the method further adding to the mixture between 0.001 to 1 wt.%. Peroxide. In some embodiments, the method further comprises polishing the hardened mixture.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

[0014] Fig. 1 is a flowchart of a method of making an artificial stone according to some embodiments of the invention.

[0015] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0016] One skilled in the art will realize the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting of the invention described herein. Scope of the invention is thus indicated by the appended claims, rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

[0017] Embodiments of the present invention are directed to an artificial stone that may have an optimized combination of transparency, mechanical strength, and safety. The present invention may address these issues by introducing an artificial stone comprising fused silica particles and acrylic resin. This combination may eliminate the presence of crystalline silica, offering a safer alternative. Selecting a closed match of refractive indices between the resin and filler may result in minimal light scattering, producing a clear, translucent appearance. This material may achieve the marble-like look traditionally desired in artificial stone without the need for pigments oradditives to achieve color or clarity. An artificial stone according to embodiments of the invention may offer superior aesthetic appeal and excellent mechanical performance, making the artificial stone suitable for applications such as kitchen countertops, flooring, and wall cladding.

[0018] In some embodiments, the artificial stone may include between, 3 to 20 wt.%, for example, between 6 to 18 wt.% acrylic resin and between, 80 to 97 wt.%, for example, 82 to 94 wt.% fused silica particles.

[0019] In some embodiments, the artificial stone may include at least 80 wt.% of fused silica particles. In some embodiments, the artificial stone may include at least 82 wt.% of fused silica particles. In some embodiments, the artificial stone may include at least 85 wt.% of fused silica particles. In some embodiments, the artificial stone may include at least 90 wt.% of fused silica particles. In some embodiments, the artificial stone may include at most 95 wt.% of fused silica particles. In some embodiments, the artificial stone may include at most 94 wt.% of fused silica particles. In some embodiments, the artificial stone may include at most 93 wt.% of fused silica particles. In some embodiments, the artificial stone may include at most 91 wt.% of fused silica particles.

[0020] In some embodiments, the fused silica particles may comprise amorphous silica having at most 1 wt.% crystalline silica from the total weight of the fused silica. For example, the fused silica particles may have at most 0.8 wt.% crystalline silica, 0.6 wt.% crystalline silica, 0.5 wt.% crystalline silica or less.

[0021] In some embodiments, the fused silica particles are characterized by a particle size of between 5 pm to 5 mm. In some embodiments, the size is defined as a median diameter ranging from 5 pm to 5 mor more. As used herein, the term "diameter" may encompass a size of at least one dimension, e.g., length. In some embodiments, the term "diameter" refers to a median size of a plurality of particles. Herein, the term "particles", refers to one or more particles. In some embodiments, the particle size may be determined using any known method such as, passing the particles through a series of mesh screens / meshes with varying apertures to separate them by size, laser diffraction, dynamic light scattering (DLS), and the like.

[0022] In some embodiments, the fused silica particles may include particles having size of 5 pm, 10 pm, 20 pm, 50 pm, 70 pm, 100 pm, 200 pm, 500 pm, 750pm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm and any value or range in between.

[0023] In some embodiments, the fused silica particles may include or may be pure fused silica with at most 0.1 wt.% of impurities from the total weight of the fused silica particles. Therefore, the fused silica particles may include trace amounts of impurities, which are generally limited toat most 0.1 % of the total weight. These impurities can include metallic oxides such as aluminum oxide (AI2O3), iron oxide ( C2O3). and titanium dioxide (TiCE), among others. The presence of these impurities is minimal and does not significantly affect the overall properties of the fused silica. The stringent control of impurity levels ensures that the fused silica maintains its exceptional optical clarity, low thermal expansion, high chemical resistance, and durability under UV radiation and high temperatures, making it an ideal component for high-performance engineered stone applications.

[0024] In some embodiments, the artificial stone may include between 3 to 20 wt.% acrylic resin. In some embodiments, the artificial stone may include at least 5 wt.% of the acrylic resin. In some embodiments, the weight percentage of the acrylic resin is between 6 to 18 wt.%. In some embodiments, the weight percentage of the acrylic resin is between 6 to 15 wt.%. In some embodiments, the weight percentage of the acrylic resin is between 7 to 17 wt.%. In some embodiments, the weight percentage of the acrylic resin is between 7 to 20 wt.%. In some embodiments, the weight percentage of the acrylic resin is between 6 to 16 wt.%.

[0025] In some embodiments, the acrylic binder may include a plurality of monomeric units selected from acrylate, or any derivative thereof.

[0026] In some embodiments, the acrylate is selected from the acrylic resin comprises at least one of: poly(methyl methacrylate) (PMMA), 2-ethylhexyl acrylate (2 -EHA), methacrylic acid (MAA), acrylic acid, urethane acrylate (UA), methyl methacrylate (MMA), 2-ethylhexyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl methacrylate, isobomyl acrylate, isobomyl methacrylate, and any derivative or combination thereof. In some embodiments, the monomeric unit comprises 2-EHA and MMA. In some embodiments, the MMA and 2-EHA are present at a weight ratio ranging from 5:1 to 3:1, respectively.

[0027] In some embodiments, the composition of the acrylic resin is selected to have a refractive index of between ± 0.25 of a refractive index of the fused silica. In some embodiments, the composition of the acrylic resin is selected to have a refractive index of between ± 0.15 of a refractive index of the fused silica. For example, the refractive index of fused silica ranges from 1.45 to 1.46 at a temperature of 20 °C, therefore, the refractive index of the acrylic resin may be selected to be between 1.2 to 1.7, between 1.3 to 1.6, between 1.25 to 1.65, between 1.35 to 1.55, or any value or range in between, at a temperature of 20 °C. Some nonlimiting examples for the selection of acrylic resin compositions according to some embodiments of the invention are given in the Examples section herein below.

[0028] In some embodiments, polymeric binder may further include a pigment. For example, the pigment may be selected from titanium-dioxide based pigments, iron-oxide based pigments, chromium-oxide based pigments, zinc-oxide based pigments, or any other organic or metal-oxide-based pigments.

[0029] In some embodiments, the polymeric binder may include additional additives. In some embodiments, the polymeric binder may include between 0.1 to 10 wt.% of one or more types of additives. In some embodiments, the additive may be selected from, a pigment, UV reflector, UV stabilizer, a wetting agent, an antibacterial additive, an emulsifier, a mechanical toughener, a scratch resistance additive, and any combination thereof.

[0030] In some embodiments, the artificial stone may further comprise a coupling agent. In some embodiments, the weight percentage of the coupling agent is between 0.001 to 1 wt.%. In some embodiments, the coupling agent is silane. In some embodiments, the weight percentage of the coupling agent is between 0.05 to 1.5 wt.%. In some embodiments, the weight percentage of the coupling agent is between 0.01 to 1 wt.%. In some embodiments, the weight percentage of the coupling agent is between 0.005 to 1 wt.%. In some embodiments, the weight percentage of the coupling agent is between 0.005 to 0.5 wt.%. In some embodiments, the amount of coupling agent is at least, 0.001 wt.%., 0.002 wt.%. 0.003 wt.%., 0.004 wt.%. 0.005 wt.%., 0.007 wt.%., 0.01 wt.%., 0.02 wt.%., 0.03 wt.%., 0.05 wt.%., 0.07 wt.%., 0.08 wt.%., 0.1 wt.%., 0.2 wt.%., 0.3 wt.%., 0.4 wt.%, and 0.05 wt.%. In some embodiments, the amount of coupling agent is at most 0.5 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, 1.1 wt.%, 1.2 wt.%, 1.3 wt.%, 1.5 wt.%, 1.7 wt.%, and 2 wt.%.

[0031] In some embodiments, the artificial stone may include between 0.001 to 1 wt.%. peroxide. In some embodiments, the selection of peroxides as polymerization initiators may be critical to achieving the desired properties of the final product. Various types of peroxides may be employed, each offering unique benefits tailored to specific production needs. Benzoyl peroxide is a commonly used organic peroxide, valued for its effectiveness in initiating polymerization at relatively low temperatures, which helps in maintaining the integrity of the acrylic resin. Methyl ethyl ketone peroxide (MEKP) is another popular choice, known for its high reactivity and suitability for room temperature curing, making it ideal for large-scale production processes. Acetyl acetone peroxide (AAP) and cyclohexanone peroxide (CHP) are also frequently utilized due to their stability and controlled decomposition rates, which contribute to uniform curing and minimize defects such as bubbles or uneven surfaces in the artificial stone. In some embodiments,organic percarbonate peroxides may also be used as peroxides for the resin as separate peroxides or in combination with other organic peroxides.

[0032] In some embodiments, the artificial stone may include between 0.001 to 1 wt.%. peroxide, for example, 0.005 wt.%, 0.01 wt.%, 0.05 wt.%, 0.1 wt.%, 0.5 wt.%, 1 wt.% or any value or range in between.

[0033] In some embodiments, the artificial stone may further include fine lines or shades of different colors for mimicking veins and areas with different colors as in a natural marble. This may be achieved by spreading, applying, printing pigments as specific areas on top of the mixture, prior to pressing and hardening.

[0034] Reference is now made to Fig. 1 which is a flowchart of a method for manufacturing an artificial stone according to some embodiments of the invention. In step 110, between 5 to 20 wt.% acrylic resin and between 80 to 95% fused silica particles, may be mixed to form a mixture.

[0035] In step 120, the mixture may be spread, for example, on a mold or a conveyor. In step 130, the mixture may be pressed, for example, using a vibrating press. In step 140, the pressed mixture is inserted into an oven at a temperature of 80-100C to be hardened (e.g., cured), for example, for 30-50- minutes, to form a slab. In some embodiments, the method may include spreading, applying, or printing pigments as specific areas on top of the mixture, prior to pressing and hardening.

[0036] In some embodiments, after curing, the slab is cooled down and then goes through a calibration and polishing process.Experimental results

[0037] Several fused silica powders having different particles sizes been mixed with acrylic resin, peroxide and silane, as shown in Table 1.Table 1

[0038] Components 1.1 to 1.5 include the optional particle size distribution within the total fused silica.

[0039] The fused silica was mixed with the resin to form the artificial stone according to the method of Fig.1. The result, showed a clearer slab, having a more natural marble-like appearance.

[0040] Table 2 shows various optional compositions of acrylic resins that were selected based on their reflective index.Table 2resin having a refractive index of between ± 0.15 of a refractive index of the fused silica, or even ± 0.05 of a refractive index of the fused silica.

[0042] Unless explicitly stated, the method embodiments described herein are not constrained to a particular order or sequence. Furthermore, all formulas described herein are intended as examples only and other or different formulas may be used. Additionally, some of the described method embodiments or elements thereof may occur or be performed at the same point in time.

[0043] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

[0044] Various embodiments have been presented. Each of these embodiments may of course include features from other embodiments presented, and embodiments not specifically described may include various features described herein.

Claims

CLAIMS1. An artificial stone comprising:6 to 16 wt.% acrylic thermoset resin; and84 to 94% fused silica particles,wherein at least 40 wt.% of the fused silica particles are characterized by a particle size larger than 100 pm.

2. The artificial stone of claim 1, wherein the composition of the acrylic resin is selected to have a refractive index of between ± 0.25 of a refractive index of the fused silica.

3. The artificial stone of claim 2, wherein the composition of the acrylic resin is selected to have a refractive index of between ± 0.15 of a refractive index of the fused silica.

4. The artificial stone of any one of claims 1 to 3, wherein the fused silica particles comprise amorphous silica having at most 1 wt.% crystalline silica from the total weight of the fused silica.

5. The artificial stone of any one of claims 1 to 4, wherein the fused silica particles are characterized by a particle size of between 5 pm to 5 mm.

6. The artificial stone of any one of claims 1 to 5, wherein the acrylic resin comprises at least one of acrylic or methacrylic monomer.

7. The artificial stone of any one of claims 1 to 6, wherein the acrylic resin comprises at least one of: poly(methyl methacrylate) (PMMA), 2-ethylhexyl acrylate (2-EHA), methacrylic acid (MAA), acrylic acid, urethane acrylate (UA)„ methyl methacrylate (MMA), 2-ethylhexyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl methacrylate, isobornyl acrylate, isobornyl methacrylate, and any derivative or combination thereof.

8. The artificial stone of any one of claims 1 to 7, further comprising a coupling agent.

9. The artificial stone of claim 8, wherein the coupling agent is silane.

10. The artificial stone of claim 8 or claim 9, wherein the weight percentage of the coupling agent is between 0.001 to 1 wt.%.

11. The artificial stone of any one of claims 1 to 10, further comprising between 0.001 to 1 wt.%. peroxide.

12. The artificial stone of any one of claims 1 to 11, further comprising at least one additive.

13. The artificial stone of claim 12, wherein the at least one additive is selected from, a pigment, UV reflector, UV stabilizer, a wetting agent, an antibacterial additive, anemulsifier, a mechanical toughener, a scratch resistance additive, and any combination thereof.

14. A method of making an artificial stone comprising:mixing between 6 to 16 wt.% acrylic resin; and between 84 to 94% fused silica particles to form a mixture;spreading the mixture;pressing using vibro-compactization the spread mixture; andhardening the pressed mixture.

15. The method of claim 14, further comprising adding to the mixture between 0.001 to 1 wt.%. coupling agent.

16. The method of claim 14 or claim 15, further comprising adding to the mixture between 0.001 to 1 wt.%. peroxide.

17. The method of any one of claims 14 to 16, further comprising polishing the hardened mixture.

Images