Catalyst-free engineered stone and artificial marble

Abstract

An artificial stone is disclosed. The artificial stone may include: between 80 to 95 wt.% of an inorganic filler; and between 5 to 20 wt.% catalyst-free unsaturated polyester thermoset binder, wherein the amount of catalyst in the artificial stone is below a detectable limit. The unsaturated polyester thermoset binder may include between 0.2 to 5 wt.%, from the weight of the binder, an organic ketone peroxide, and wherein the organic ketone peroxide may be the only peroxide added to the unsaturated polyester thermoset binder.

Description

CST-P-019-PCTCATALYST-FREE ENGINEERED STONE AND ARTIFICIAL MARBLECROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 63 / 730,492, filed 11 December 2024, and Israeli Application No. 319663, filed on 17 March 2025. The contents of the above applications are all incorporated by reference as if fully set forth herein in their entirety.FIELD OF THE INVENTION

[0002] The present invention relates generally to slabs from artificial stones. More specifically, the present invention relates to catalyst-free engineered stone and artificial marble.BACKGROUND OF THE INVENTION

[0003] Engineered stones (also known in the art as artificial stones, agglomerated stone, artificial marble, 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 react with one or more di-alcohols. The Resin mixture also comprises additives, such as, a reactive solvent, e.g., styrene, and cobaltoctoate as a curing process accelerator. 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 methods for polymerizing unsaturated polyester resin (UPR) in these applications rely on organic peroxides with metallic catalysts. These methods present severalCST-P-019-PCT limitations, including unwanted coloration from metallic catalysts, safety concerns due to metallic residues, and suboptimal curing performance with certain fillers.

[0006] One traditional method involves the use of peroxyester-catalyst polymerization. This method includes the following steps: preparing a binder mixture of UPR; a metal catalyst salt at 0.01-0.5% by weight of the binder, and peroxyester at 0.2-4% by weight of the resin, depending on the desired curing profile. The binder mixture and pigments are added to the fillers to form the artificial stone mixture. The mixture may then be spread evenly to form the dimensions of a slab, and pressed using vibro-compression while applying a vacuum to remove air bubbles and eliminate air voids. The pressed mixture may then be cured at a temperature of between 60-110°C, depending on the peroxide used.

[0007] These methods present several limitations, including unwanted coloration from metallic catalysts, safety concerns due to metallic residues, and suboptimal curing performance with certain fillers.

[0008] Therefore, there is a need for new catalyst-free UPR artificial stone.SUMMARY OF THE INVENTION

[0009] Some aspects of the invention are directed at to an artificial stone that may include: between 80 to 95 wt.% of an inorganic filler; and between 5 to 20 wt.% catalyst- free unsaturated polyester thermoset binder, wherein the amount of catalyst in the artificial stone is below a detectable limit. In some embodiments, the unsaturated polyester thermoset binder may include between 0.2 to 5 wt.%, from the weight of the binder, an organic ketone peroxide, and wherein the organic ketone peroxide may be the only peroxide added to the unsaturated polyester thermoset binder.

[0010] In some embodiments, the detectable limit may be 1 ppm, from the total weight of the artificial stone. In some embodiments, the detectable limit is 0.1 ppm, from the total weight of the artificial stone.

[0011] Some additional aspects of the invention may be directed to a mixture for an artificial stone. The mixture may include between 80 to 95 wt.% of an inorganic filler; and between 5 to 20 wt.% catalyst-free unsaturated polyester thermoset binder, wherein the amount of catalyst in is below a detectable limit. In some embodiments, the unsaturated polyester thermoset binder may include between 0.2 to 5 wt.%, from the weight of the binder, an organic ketone peroxide, and wherein the organic ketone peroxide may be the only peroxide added to the unsaturated polyester thermoset binder.CST-P-019-PCT

[0012] In some embodiments, the unsaturated polyester thermoset binder may include: between 0.1 to 1 wt.%, from the weight of the binder, peroxydicarbonate; and between 1 to 4 wt.%, from the weight of the binder, peroxy ester.

[0013] Some additional aspects of the invention may be directed to a method of making catalyst-free artificial stone comprising: providing unsaturated polyester thermoset binder mixture; adding to the mixture one of: (a) between 0.2 to 5 wt.%, from the weight of the binder, an organic ketone peroxide wherein the organic ketone peroxide is the only peroxide added to the unsaturated polyester thermoset binder; adding to the mixture between 80 to 95 wt.% of an inorganic filler; spreading the mixture evenly to form a product; pressing the mixture; and curing the mixture at between 60 tol 10°C.

[0014] Some additional aspects of the invention may be directed to an artificial stone comprising: between 80 to 95 wt.% of an inorganic filler; and between 5 to 20 wt.% catalyst- free unsaturated polyester thermoset binder, wherein the amount of catalyst in the artificial stone is below a detectable limit, and wherein the unsaturated polyester thermoset binder comprises between 0.2 to 5 wt.%, from the weight of the binder a mixture of two or more peroxides comprising Peroxydicarbonate and at least one additional different peroxide.

[0015] In some embodiments, the detectable limit is 1 ppm, from the total weight of the artificial stone. In some embodiments, the detectable limit is 0.1 ppm, from the total weight of the artificial stone.

[0016] Some additional aspects of the invention may be directed to a mixture for an artificial stone, comprising: between 80 to 95 wt.% of an inorganic filler; and between 5 to 20 wt.% catalyst-free unsaturated polyester thermoset binder, wherein the amount of catalyst in is below a detectable limit, and wherein the unsaturated polyester thermoset binder comprises between 0.2 to 5 wt.%, from the weight of the binder a mixture of two or more peroxides comprising peroxydicarbonate and at least one additional different peroxide.

[0017] In some embodiments, the mixture may include: between 0.1 to 1 wt.%, from the weight of the binder, peroxydicarbonate; and between 1 to 4 wt.%, from the weight of the binder, peroxyester.

[0018] Some additional aspects of the invention may be directed to a method of making catalyst-free artificial stone comprising: providing unsaturated polyester thermoset binder mixture; adding to the mixturevbetween 0.2 to 5 wt.%, from the weight of the binder a mixture of two or more peroxides comprising peroxydicarbonate and at least one additional different peroxide; adding to the mixture between 80 to 95 wt.% of an inorganic filler;CST-P-019-PCT spreading the mixture evenly to form a product; pressing the mixture; and curing the mixture at between 60 tol 10°CBRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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:

[0020] Fig. 1 is a flowchart of a method of making an artificial stone according to some embodiments of the invention.

[0021] 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

[0022] 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.

[0023] Embodiments of the present invention disclose a catalyst-free artificial stone. The absence of metallic catalysts may eliminate unwanted coloration, such as pink or purple hues, which can limit design flexibility. These results may provide a broader range of aesthetic possibilities, allowing for the creation of more vibrant and customizable patterns and colors that are not achievable with traditional methods. In some embodiments, the elimination of metallic residues enhances the safety and environmental compliance of the final product, making it suitable for sensitive applications where metallic contamination is a concern.CST-P-019-PCT

[0024] Additionally, catalyst-free systems may exhibit superior reactivity with various fillers, including glass particles, leading to improved curing performance and mechanical properties. This enhanced reactivity may ensure a more homogeneous and robust final product. Furthermore, the process flexibility of catalyst-free systems may allow for controlled reaction kinetics, making them adaptable to diverse manufacturing conditions and enabling more efficient production processes. Overall, catalyst-free artificial stone may represent a significant advancement in the field, offering improved aesthetics, safety, performance, and manufacturing efficiency.

[0025] As should be understood, the term “artificial stone” is interchangeable with, “engineered stone”, “artificial marble”, “agglomerated stone”, and “quartz slabs”.

[0026] In some embodiments, an artificial stone may include between 80 to 95 wt.% of an inorganic filler, and between 5 to 20 wt.% catalyst-free unsaturated polyester thermoset binder, wherein the amount of catalyst is below a detectable limit. In some embodiments, the unsaturated polyester thermoset binder may include an oligomeric chain formed by the reaction of saturated and unsaturated dicarboxylic acids (or their anhydrides) with one or more di-alcohols. The unsaturated polyester resin (UPR) is characterized by the presence of reactive double bonds in its backbone, which facilitate crosslinking during the curing process. In some embodiments, the binder may include catalyst-free additives, such as pigments, wetting additives, coupling agents, UV absorbers, antimicrobial additives, toughness, hardness modifiers and / or nano particles, and the like.

[0027] In some embodiments, the artificial stone may include at least 80 wt.% of an inorganic filler. In some embodiments, the artificial stone may include at least 82 wt.% of an inorganic filler. In some embodiments, the artificial stone may include at least 85 wt.% of an inorganic filler. In some embodiments, the artificial stone may include at least 90 wt.% of an inorganic filler. In some embodiments, the artificial stone may include at most 95 wt.% of an inorganic filler. In some embodiments, the artificial stone may include at most 94 wt.% of an inorganic filler. In some embodiments, the artificial stone may include at most 93 wt.% of an inorganic filler. In some embodiments, the artificial stone may include at most 91 wt.% of an inorganic filler.

[0028] In some embodiments, the inorganic filler is selected from quartz, feldspar, quartzite amorphous silica, glass particles, frits, or any combination thereof.

[0029] In some embodiments, the inorganic filler (or aggregates) is in the form of a plurality of particles having a median diameter ranging from 0.001 to 10 mm or more. AsCST-P-019-PCT 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.

[0030] In some embodiments, the inorganic filler may include a mixture of two or more types of aggregates, for example, 50 wt.% quartzite and 50 wt.% quartz, or 20 wt.% quartzite and 80 wt.% quartz.

[0031] As used herein “amount of catalyst that is below a detectable limit” refers to the inability to detect any traces of metallic catalyst using, for example, X-ray fluorescence (XRF) spectroscopy, meaning that the detectable limit is 1 ppm, from the total weight of the artificial stone. In yet another example, wet chemical analysis may be used to detect traces of metallic catalysts, therefore, the detectable limit is 0.1 ppm, from the total weight of the artificial stone. Both of these measurements may indicate that the artificial stone is free from any metallic catalyst.

[0032] In order to replace the metallic catalyst as a polymerizing agent for unsaturated polyester thermoset, several approaches are suggested. In some embodiments, a pre-cured mixture for making an artificial stone may include between 80 to 95 wt.% of an inorganic filler, and between 5 to 20 wt.% catalyst-free unsaturated polyester thermoset binder, wherein the amount of catalyst is below a detectable limit. To this mixture, one of the two following additions may be added in order to facilitate polymerizing of the unsaturated polyester.

[0033] In a first embodiment, catalyst-free peroxides, such as, organic ketone peroxides, and peroxydicarbonates may be added to the mixture in an amount of between 0.2 to 5 wt.%, from the weight of the binder. For example, organic ketone peroxides and peroxydicarbonates may be added in an amount of, 0.2 wt.%, 0.5 wt.%, 0.7 wt.%, 1 wt.%, 1.2 wt.%, 1.5 wt.%, 1.7 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 4 wt.%, 4.5 wt.%, 5 wt.% and any value or range in between. In some embodiments, the mixture may include between 0.2 to 5 wt.%, from the weight of the binder, an organic ketone peroxide, and wherein the organic ketone peroxide may be the only peroxide added to the unsaturated polyester thermoset binder. In such case no additional peroxide may be needed in order to form a catalyst free artificial stone. Some nonlimiting examples for organic ketone peroxides may include Methyl Ethyl Ketone Peroxide (MEKP), Methyl Isobutyl Ketone Peroxide (MIBKP), Cyclohexanone Peroxide, Acetyl Acetone Peroxide, Diacetone Alcohol Peroxide, and the like. Some nonlimiting examples for peroxydicarbonates may include,CST-P-019-PCTDi(4-tert-butylcyclohexyl) Peroxydicarbonate (BCHPC), Dibutyl Peroxydicarbonate, Di(2- ethylhexyl) Peroxydicarbonate, Di-isopropyl Peroxydicarbonate, Di-cyclohexyl Peroxydicarbonate, and the like. These peroxides may initiate and support the curing of unsaturated polyesters.

[0034] In a second embodiment, traditional peroxides, for example, peroxyesters may be used together with peroxydicarbonates, meaning that the mixture must include peroxydicarbonates and at least one additional peroxide. In such a chemical system the peroxydicarbonates may replace the metallic catalysts. In some embodiments, the unsaturated polyester binder may further include peroxydicarbonates at between 0.1 to 1 wt.%, from the weight of the binder. The peroxydicarbonates, as listed above, may be used as “kicker” for a curing process that may be performed by peroxyester at an amount of between 1 to 4 wt.%, from the weight of the binder. Some nonlimiting examples for peroxyester may include, tert-Butyl Peroxybenzoate (TBPB), tert-Butyl Peroxy-3,5,5- trimethylhexanoate, tert-Butyl Peroxyacetate, tert-Butyl Peroxyisobutyrate, Cumyl Peroxyneodecanoate, tert-Butyl Peroxypivalate, and the like.

[0035] In some embodiments, the binder may include peroxydicarbonates at an amount of, 0.1 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, 1 wt.%, from the weight of the binder, and any amount or range in between. In some embodiments, the binder may include peroxyester at an amount of 1 wt.%, 1.5 wt.%, 2 wt.%, 2.5 wt.%, 3 wt.%, 3.5 wt.%, 4 wt.% from the weight of the binder, and any amount or range in between.

[0036] In some embodiments, the mixture may further include pigments, and any additional additives selected from, wetting additives, coupling agents, UV absorbers, antimicrobial additives, toughness, hardness modifiers and / or nano particles, and the like, and any combination thereof.

[0037] Reference is now made to Fig. 1 which is a method of making catalyst-free artificial stone according to some embodiments of the invention. In step 110, the method may include providing an unsaturated polyester thermoset binder mixture. In some embodiments, additives such as [wetting additives, coupling agents, UV absorbers, antimicrobial additives, toughness, hardness modifiers and / or nano particles, and the like] may be added to the unsaturated polyester thermoset binder mixture.

[0038] In step 120A, the method may include adding to the mixture between 0.2 to 5 wt.%, from the weight of the binder, of least one of, organic ketone peroxides andCST-P-019-PCT peroxydicarbonates, as discussed herein above. Alternatively, in step 120B the method may include adding to the mixture between 0.1 to 1 wt.%, from the weight of the binder, peroxy dicarbonates, and between 1 to 4 wt.%, from the weight of the binder, peroxy ester, as discussed herein above.

[0039] In step 130, the method may include adding to the mixture between 80 to 95 wt.% of an inorganic filler. The inorganic filler may be selected from quartz, feldspar, quartzite amorphous silica, glass particles, frits, or any combination thereof.

[0040] The binder and the filler may be mixed in any known mixer. In step 140, the method may include spreading the mixture evenly to form a product. In a nonlimiting example, the mixture may be introduced into a weighing and dosing unit to be spread on a conveyor or a mold.

[0041] In step 150, the method may include pressing the mixture. In a nonlimiting example, the pressing may be done using vibro-compression while applying a vacuum to remove air bubbles and eliminate air voids.

[0042] In step 160, the method may include curing the pressed mixture in an oven at temperatures between 60 to 110 °C. In some embodiments, the curing temperature may be determined based on the peroxide added to the mixture.

[0043] In some embodiments, additional finishing processes may be performed on the hard-cured product. For example, the product (e.g., a slab) may be polished and the upper surface of the slab may be calibrated to form a substantially flat surface.Examples

[0044] Several compositions according to embodiments of the invention were made and tested.Example 1 : Catalyst-Free Ketone Peroxide Polymerization

[0045] 15% (w / w) UPR, mixed with a silane, such as 3-Methacryloxypropyltrimethoxysilane (MEMO), was further mixed with soda lime glass (85% w / w) and MEKP (2% w / w). The mixture was pressed and cured at 90°C. The result showed a cured composite with no discoloration or metallic residues.Example 2: Catalyst-Free Peroxy dicarbonate PolymerizationCST-P-019-PCT

[0046] 15% (w / w) UPR was mixed with quartz filler (85% w / w), and BCHPC (2% w / w).The pressed mixture was cured at 90°C. The result showed a rapid curing with enhanced clarity and strength.Example 3: Dual Peroxide System

[0047] 15% (w / w) UPR was mixed with glass particles (90% w / wand BCHPC (0.5% w / w), and TBPB (1.5% w / w). The pressed mixture was cured at 85°C. The result showed an optimized polymerization with excellent filler-resin bonding and no metallic residues.Example 4: Traditional Peroxyester-Catalyst PolymerizationA comparison to traditional catalysts included artificial stone was made. 11% (w / w) UPR was mixed with cobalt catalyst (0.2% w / w) and TBPB (2% w / w) and feldspar (89%) filler. The pressed mixture was cured at 85C. The results showed an effective curing but with pink coloration and metallic residues.

[0048] 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.

[0049] 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.

[0050] 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

CST-P-019-PCTCLAIMS1. An artificial stone comprising: between 80 to 95 wt.% of an inorganic filler; and between 5 to 20 wt.% catalyst-free unsaturated polyester thermoset binder, wherein the amount of catalyst in the artificial stone is below a detectable limit, and wherein the unsaturated polyester thermoset binder comprises between 0.2 to 5 wt.%, from the weight of the binder, an organic ketone peroxide, and wherein the organic ketone peroxide is the only peroxide added to the unsaturated polyester thermoset binder.

2. The artificial stone of claim 1, wherein the detectable limit is 1 ppm, from the total weight of the artificial stone.

3. The artificial stone of claim 1, wherein the detectable limit is 0.1 ppm, from the total weight of the artificial stone.

4. A mixture for an artificial stone, comprising: between 80 to 95 wt.% of an inorganic filler; and between 5 to 20 wt.% catalyst-free unsaturated polyester thermoset binder, wherein the amount of catalyst in is below a detectable limit, and wherein the unsaturated polyester thermoset binder comprises between 0.2 to 5 wt.%, from the weight of the binder, an organic ketone peroxide, and wherein the organic ketone peroxide is the only peroxide added to the unsaturated polyester thermoset binder.

5. The mixture of claim 4, wherein the unsaturated polyester thermoset binder comprises: between 0.1 to 1 wt.%, from the weight of the binder, peroxydicarbonate; and between 1 to 4 wt.%, from the weight of the binder, peroxyester.

6. A method of making catalyst-free artificial stone comprising: providing unsaturated polyester thermoset binder mixture; adding to the mixture one of: between 0.2 to 5 wt.%, from the weight of the binder, of least one of, organic ketone peroxides and peroxy dicarbonates; or adding to the mixture between 80 to 95 wt.% of an inorganic filler; spreading the mixture evenly to form a product;CST-P-019-PCT pressing the mixture; and curing the mixture at between 60 tol 10°C.

7. An artificial stone comprising: between 80 to 95 wt.% of an inorganic filler; and between 5 to 20 wt.% catalyst-free unsaturated polyester thermoset binder, wherein the amount of catalyst in the artificial stone is below a detectable limit, and wherein the unsaturated polyester thermoset binder comprises between 0.2 to 5 wt.%, from the weight of the binder a mixture of two or more peroxides comprising Peroxydicarbonate and at least one additional different peroxide.

8. The artificial stone of claim 7, wherein the detectable limit is 1 ppm, from the total weight of the artificial stone.

9. The artificial stone of claim 7, wherein the detectable limit is 0.1 ppm, from the total weight of the artificial stone.

10. A mixture for an artificial stone, comprising: between 80 to 95 wt.% of an inorganic filler; and between 5 to 20 wt.% catalyst-free unsaturated polyester thermoset binder, wherein the amount of catalyst in is below a detectable limit, and wherein the unsaturated polyester thermoset binder comprises between 0.2 to 5 wt.%, from the weight of the binder a mixture of two or more peroxides comprising peroxydicarbonate and at least one additional different peroxide.

11. The mixture of claim 4, wherein the mixture comprises: between 0.1 to 1 wt.%, from the weight of the binder, peroxydicarbonate; and between 1 to 4 wt.%, from the weight of the binder, peroxyester.

12. A method of making catalyst-free artificial stone comprising: providing unsaturated polyester thermoset binder mixture; adding to the mixture one of: between 0.2 to 5 wt.%, from the weight of the binder a mixture of two or more peroxides comprising peroxydicarbonate and at least one additional different peroxide; adding to the mixture between 80 to 95 wt.% of an inorganic filler; spreading the mixture evenly to form a product;CST-P-019-PCT pressing the mixture; and curing the mixture at between 60 tol 10°C.

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