Lightweight artificial granite slab and preparation process thereof

Abstract

The invention discloses a lightweight artificial granite slab and a preparation process thereof, and belongs to the technical field of slab preparation, and the preparation process comprises the following steps: S1, pretreating a substrate; s2, spraying bottom layer slurry on the pretreated substrate; s3, spraying pattern layer slurry and transparent protection layer slurry on the bottom layer slurry; and S4, the sprayed plate is cured step by step, the cured plate is subjected to surface treatment, and the light artificial granite plate is obtained. According to the invention, the artificial granite plate with light weight, high strength and excellent durability is prepared through the synergistic effect of the substrate pretreatment, the biomass modified phenolic prepolymer and the modified hollow ceramic microspheres.

Description

Technical Field

[0001] The invention relates to the technical field of plate preparation, and in particular to a lightweight artificial granite plate and a preparation process thereof. Background Art

[0002] As an important building decoration material, granite slabs are widely used in various occasions such as interior and exterior walls, floors, countertops, etc. due to their hard texture, beautiful color, and good wear resistance. At present, the granite slabs used in the market are mainly divided into two categories: natural granite and artificial granite.

[0003] Natural granite is an igneous rock composed of minerals such as quartz, feldspar and mica. It is mined from natural mines and processed through cutting, polishing and other processes. However, natural granite has problems such as high density, excessive weight, limited resources and environmental damage during the mining process. In addition, although natural granite has a high hardness, it is also very brittle and has limited flexural strength, making it prone to fracture in certain application scenarios. Summary of the invention

[0004] The invention discloses a light artificial granite plate and a preparation process thereof, which solves the technical problems of high density, great brittleness and limited flexural strength of natural granite plates in the prior art.

[0005] The preparation process of the lightweight artificial granite slab disclosed in the present invention comprises the following steps: S1, pre-treating the substrate; S2, spraying the bottom slurry on the pretreated substrate; S3, spraying the pattern layer slurry and the transparent protective layer slurry on the bottom slurry; S4, curing the sprayed plate in steps, and performing surface treatment on the cured plate to obtain a lightweight artificial granite plate.

[0006] Preferably, the base slurry is composed of the following components: 40-50 parts of unsaturated polyester resin, 15-20 parts of biomass-modified phenolic prepolymer, 20-25 parts of modified hollow ceramic microspheres, 2-4 parts of nano-silicon dioxide, and 1-3 parts of curing agent.

[0007] Preferably, the preparation method of the modified hollow ceramic microspheres is: drying the hollow ceramic microspheres at 100-110° C. for 10-14 hours, placing them in a 95% ethanol solution of KH-550 and stirring them for 1.5-2.5 hours, filtering them and drying them at 70-85° C. for 3-5 hours to obtain modified hollow ceramic microspheres.

[0008] Preferably, the preparation method of the biomass-modified phenolic prepolymer is: enzymatically hydrolyzed lignin and phenol are mixed in a mass ratio of 1:5, a formaldehyde solution with a concentration of 37wt% is added, the reaction temperature is controlled at 83-87°C under the condition of pH=9.3-9.7, the reaction is carried out for 2-3 hours, the temperature is lowered to 25°C, the pH is adjusted to 6.5-7.0 with dilute hydrochloric acid, and water is removed by vacuum rotary evaporation to obtain the biomass-modified phenolic prepolymer.

[0009] Preferably, the amount of KH-550 is 2% to 3%wt of the hollow ceramic microspheres.

[0010] Preferably, the molar ratio of phenol to formaldehyde is 1:1.8.

[0011] Preferably, the spraying process parameters of step S2 are: spraying pressure of 0.32-0.38 MPa, spraying distance of 23-27 cm, and thickness of 1.1-1.3 mm.

[0012] Preferably, the unsaturated polyester resin is an orthophthalic unsaturated polyester resin with a molecular weight ranging from 2200 to 2800 g / mol.

[0013] Preferably, the substrate pretreatment in step S1 includes: Choose granite slab as substrate, use high-pressure air gun to remove surface dust, use isopropyl alcohol to wipe and degrease the surface, dry at room temperature for 20 to 40 minutes, apply primer with a primer coating amount of 140 to 160 g / m2, and pre-dry at 55 to 65°C for 40 to 50 minutes.

[0014] The present invention also provides a lightweight artificial granite slab prepared by the above-mentioned preparation process.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The density of the lightweight artificial granite slab prepared by the present invention is 1945-2010 kg / m³, which is significantly lower than that of natural granite. At the same time, the flexural strength reaches 27.2-29.6 MPa, which is 80%-97% higher than that of natural granite, thereby achieving the goal of reducing the density of the granite slab while increasing its strength.

[0016] (2) The water absorption rate of the board prepared by the present invention is lower than that of natural granite, indicating that the material has excellent stability in a humid environment; in the freeze-thaw resistance test, the strength loss rate is only 2.2% to 2.8%, which is close to that of natural granite.

[0017] (3) The present invention significantly enhances the compatibility of the interface between the slurry and the microspheres by using KH-550 to modify the surface of the hollow ceramic microspheres, and effectively improves the overall performance and structural stability of the composite material.

[0018] (4) The present invention prepares a modified phenolic prepolymer by mixing enzymatically hydrolyzed lignin with phenol, which not only realizes the high-value utilization of biomass resources, but also significantly improves the toughness and environmental resistance of the material.

[0019] In summary, the present invention prepares an artificial granite slab with light weight, high strength and excellent durability through the synergistic effect of substrate pretreatment, biomass-modified phenolic prepolymer and modified hollow ceramic microspheres. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The granite slab used in this embodiment is a commercially available standard granite slab for construction, with a specification of 600mm×300mm×15mm, and a fine-grained gray-white granite. The surface of the slab is subjected to standard mechanical polishing treatment, and the flatness error is controlled within ±0.5mm. The edges are chamfered to avoid sharp edges, and the density is about 2650kg / m³, and the compressive strength is about 180MPa. The unsaturated polyester resin used is an orthophthalic unsaturated polyester resin, and the molecular weight range is 2200-2800g / mol; The pattern layer slurry used in the embodiment of the present application is composed of the following components: 40 parts of orthophthalic unsaturated polyester resin; 12 parts of iron oxide pigment; 25 parts of granite powder; 8 parts of mica powder; 5 parts of titanium dioxide; 2 parts of fumed silica thickener; 1.5 parts of polycarboxylate dispersant; 1.8 parts of methyl ethyl ketone peroxide curing agent; 0.6 parts of cobalt cyclooctanoate accelerator. The spraying process of the pattern layer is a spraying pressure of 0.30MPa, a spraying distance of 20cm, and a thickness of 0.8mm; the enzymatic lignin used comes from Shandong Longli Biotechnology Co., Ltd., which is corn straw enzymatic lignin; the curing agent used comes from Jiangsu Sanmu Group Co., Ltd., model M-50.

[0022] The transparent protective layer slurry used in the embodiment of the present application is composed of the following components: methyl methacrylate modified unsaturated polyester resin: 55 parts; nano silicon dioxide: 4 parts; hydroxybenzotriazole ultraviolet absorber: 2 parts; hindered phenol antioxidant: 1.5 parts; polysiloxane leveling agent: 1 part; di-tert-butyl peroxide curing agent: 2.5 parts; polyvinyl butyral low shrinkage agent: 3 parts. The spraying pressure of the transparent protective layer slurry spraying process is 0.30MPa, the spraying distance is 20cm, and the thickness is 0.6mm.

[0023] Example 1 This embodiment provides a process for preparing a lightweight artificial granite slab.

[0024] S1. Use a granite plate as the substrate, use a high-pressure air gun with an air pressure of 0.5 MPa to remove surface dust, then use isopropyl alcohol to wipe and degrease the surface of the substrate, and dry it at 25°C for 30 minutes.

[0025] S2. Apply primer with a coating amount of 150g / m² and pre-dry at 60°C for 45 minutes to complete substrate pretreatment.

[0026] S3. Spraying a base slurry on the pretreated substrate, the base slurry consisting of the following components: 45 parts of o-phthalic unsaturated polyester resin, 18 parts of biomass modified phenolic prepolymer, 22 parts of modified hollow ceramic microspheres, 3 parts of nano-silicon dioxide, and 2 parts of curing agent.

[0027] Among them, the preparation method of biomass modified phenolic prepolymer is: enzymatically hydrolyzed lignin and phenol are mixed in a mass ratio of 1:5, a formaldehyde solution with a concentration of 37wt% is added, and the molar ratio of phenol to formaldehyde is 1:1.8. Under the condition of pH=9.5, the reaction temperature is controlled at 85°C, the reaction is carried out for 2.5 hours, and after cooling to 25°C, the pH is adjusted to 6.8 with dilute hydrochloric acid, and the water is removed by vacuum rotary evaporation to obtain biomass modified phenolic prepolymer.

[0028] The preparation method of the modified hollow ceramic microspheres is as follows: the hollow ceramic microspheres are dried at 105°C for 12 hours, placed in a 95% ethanol solution of KH-550 and stirred for 2 hours, the amount of KH-550 used is 2.5%wt of the hollow ceramic microspheres, filtered and dried at 80°C for 4 hours to obtain modified hollow ceramic microspheres.

[0029] The bottom slurry spraying process parameters are: spraying pressure 0.35MPa, spraying distance 25cm, thickness 1.2mm.

[0030] S4. Spray the pattern layer slurry and the transparent protective layer slurry on the bottom slurry in sequence, and then perform step-by-step curing on the sprayed plate. The curing temperature is first maintained at 60°C for 1 hour, then maintained at 80°C for 2 hours, and finally maintained at 120°C for 0.5 hour. The cured plate is surface treated, including sanding and polishing, to obtain a lightweight artificial granite plate.

[0031] Example 2 This embodiment provides a process for preparing a lightweight artificial granite slab.

[0032] S1. Use a granite plate as the substrate, use a high-pressure air gun with an air pressure of 0.6 MPa to remove surface dust, then use isopropyl alcohol to wipe and degrease the surface of the substrate, and dry it at 24°C for 25 minutes.

[0033] S2. Apply primer with a primer coating amount of 145g / m² and pre-dry at 58°C for 42 minutes to complete substrate pretreatment.

[0034] S3. Spraying a base slurry on the pretreated substrate, the base slurry consisting of the following components: 40 parts of ortho-phthalic unsaturated polyester resin, 15 parts of biomass-modified phenolic prepolymer, 25 parts of modified hollow ceramic microspheres, 4 parts of nano-silicon dioxide, and 3 parts of curing agent.

[0035] Among them, the preparation method of biomass modified phenolic prepolymer is: enzymatically hydrolyzed lignin and phenol are mixed in a mass ratio of 1:5, a formaldehyde solution with a concentration of 37wt% is added, and the molar ratio of phenol to formaldehyde is 1:1.8. Under the condition of pH=9.3, the reaction temperature is controlled at 83°C, the reaction is carried out for 2 hours, the temperature is lowered to 25°C, the pH is adjusted to 7.0 with dilute hydrochloric acid, and the water is removed by vacuum rotary evaporation to obtain biomass modified phenolic prepolymer.

[0036] The preparation method of the modified hollow ceramic microspheres is as follows: drying the hollow ceramic microspheres at 100°C for 10 hours, placing them in a 95% ethanol solution of KH-550 and stirring them for 1.5 hours, wherein the amount of KH-550 is 2.0%wt of the hollow ceramic microspheres, filtering and drying them at 70°C for 3 hours to obtain modified hollow ceramic microspheres.

[0037] The bottom slurry spraying process parameters are: spraying pressure 0.32MPa, spraying distance 23cm, thickness 1.1mm.

[0038] S4, spray the pattern layer slurry and the transparent protective layer slurry on the bottom slurry in sequence, and then perform step-by-step curing on the sprayed plate, the curing temperature is first maintained at 55°C for 1.5 hours, then maintained at 75°C for 2.5 hours, and finally maintained at 115°C for 0.8 hours. The cured plate is surface treated, including sanding and polishing, to obtain a lightweight artificial granite plate.

[0039] Example 3 This embodiment provides a process for preparing a lightweight artificial granite slab.

[0040] S1. Use a granite plate as the substrate, use a high-pressure air gun with an air pressure of 0.55 MPa to remove surface dust, then use isopropyl alcohol to wipe and degrease the surface of the substrate, and dry it at 26°C for 40 minutes.

[0041] S2. Apply primer with a coating amount of 160g / m² and pre-dry at 65°C for 50 minutes to complete substrate pretreatment.

[0042] S3. Spraying a base slurry on the pretreated substrate, the base slurry consisting of the following components: 50 parts of o-phthalic unsaturated polyester resin, 20 parts of biomass modified phenolic prepolymer, 20 parts of modified hollow ceramic microspheres, 2 parts of nano-silica, and 1 part of curing agent.

[0043] Among them, the preparation method of biomass modified phenolic prepolymer is: enzymatically hydrolyzed lignin and phenol are mixed in a mass ratio of 1:5, a formaldehyde solution with a concentration of 37wt% is added, and the molar ratio of phenol to formaldehyde is 1:1.8. Under the condition of pH=9.7, the reaction temperature is controlled at 87°C, the reaction is carried out for 3 hours, and after cooling to 25°C, the pH is adjusted to 6.5 with dilute hydrochloric acid, and the water is removed by vacuum rotary evaporation to obtain biomass modified phenolic prepolymer.

[0044] The preparation method of the modified hollow ceramic microspheres is as follows: the hollow ceramic microspheres are dried at 110°C for 14 hours, placed in a 95% ethanol solution of KH-550 and stirred for 2.5 hours, the amount of KH-550 used is 3.0%wt of the hollow ceramic microspheres, filtered and dried at 85°C for 5 hours to obtain modified hollow ceramic microspheres.

[0045] The bottom slurry spraying process parameters are: spraying pressure 0.38MPa, spraying distance 27cm, thickness 1.3mm.

[0046] S4, spray the pattern layer slurry and the transparent protective layer slurry on the bottom slurry in sequence, and then cure the sprayed plate in steps, the curing temperature is first kept at 65°C for 1.2 hours, then kept at 85°C for 1.8 hours, and finally kept at 125°C for 0.6 hours. The cured plate is surface treated, including sanding and polishing, to obtain a lightweight artificial granite plate.

[0047] Example 4 This embodiment provides a process for preparing a lightweight artificial granite slab.

[0048] S1. Use a granite plate as the substrate, use a high-pressure air gun with an air pressure of 0.58 MPa to remove surface dust, then use isopropyl alcohol to wipe and degrease the surface of the substrate, and dry it at 23°C for 35 minutes.

[0049] S2. Apply primer with a primer coating amount of 155g / m² and pre-dry at 62°C for 48 minutes to complete substrate pretreatment.

[0050] S3. Spraying a base slurry on the pretreated substrate, the base slurry consisting of the following components: 48 parts of ortho-phthalic unsaturated polyester resin, 17 parts of biomass-modified phenolic prepolymer, 23 parts of modified hollow ceramic microspheres, 3.5 parts of nano-silicon dioxide, and 1.5 parts of a curing agent.

[0051] Among them, the preparation method of biomass modified phenolic prepolymer is: enzymatically hydrolyzed lignin and phenol are mixed in a mass ratio of 1:5, a formaldehyde solution with a concentration of 37wt% is added, the molar ratio of phenol to formaldehyde is 1:1.8, under the condition of pH=9.4, the reaction temperature is controlled at 84°C, the reaction is carried out for 2.2 hours, the temperature is cooled to 25°C, the pH is adjusted to 6.7 with dilute hydrochloric acid, and the water is removed by vacuum rotary evaporation to obtain biomass modified phenolic prepolymer.

[0052] The preparation method of the modified hollow ceramic microspheres is as follows: the hollow ceramic microspheres are dried at 108°C for 13 hours, placed in a 95% ethanol solution of KH-550 and stirred for 2.3 hours, the amount of KH-550 used is 2.8%wt of the hollow ceramic microspheres, filtered and dried at 82°C for 4.5 hours to obtain modified hollow ceramic microspheres.

[0053] The bottom slurry spraying process parameters are: spraying pressure 0.37MPa, spraying distance 26cm, thickness 1.25mm.

[0054] S4. Spray the pattern layer slurry and the transparent protective layer slurry on the bottom slurry in sequence, and then perform step-by-step curing on the sprayed plate, with the curing temperature first maintained at 63° C. for 1.3 hours, then maintained at 83° C. for 2.2 hours, and finally maintained at 122° C. for 0.7 hours. The cured plate is surface treated, including sanding and polishing, to obtain a lightweight artificial granite plate.

[0055] Example 5 This embodiment provides a process for preparing a lightweight artificial granite slab.

[0056] S1. Use a granite plate as the substrate, use a high-pressure air gun with an air pressure of 0.52 MPa to remove surface dust, then use isopropyl alcohol to wipe and degrease the surface of the substrate, and dry it at 22°C for 20 minutes.

[0057] S2. Apply primer with a coating amount of 140g / m² and pre-dry at 55°C for 40 minutes to complete substrate pretreatment.

[0058] S3. Spraying a base slurry on the pretreated substrate, the base slurry consisting of the following components: 42 parts of ortho-phthalic unsaturated polyester resin, 16 parts of biomass-modified phenolic prepolymer, 24 parts of modified hollow ceramic microspheres, 2.5 parts of nano-silicon dioxide, and 2.5 parts of curing agent.

[0059] Among them, the preparation method of biomass modified phenolic prepolymer is: enzymatically hydrolyzed lignin and phenol are mixed in a mass ratio of 1:5, a formaldehyde solution with a concentration of 37wt% is added, and the molar ratio of phenol to formaldehyde is 1:1.8. Under the condition of pH=9.6, the reaction temperature is controlled at 86°C, the reaction is carried out for 2.8 hours, and after cooling to 25°C, the pH is adjusted to 6.6 with dilute hydrochloric acid, and the water is removed by vacuum rotary evaporation to obtain biomass modified phenolic prepolymer.

[0060] The preparation method of the modified hollow ceramic microspheres is as follows: the hollow ceramic microspheres are dried at 102°C for 11 hours, placed in a 95% ethanol solution of KH-550 and stirred for 2.0 hours, the amount of KH-550 used is 2.3%wt of the hollow ceramic microspheres, filtered and dried at 75°C for 3.5 hours to obtain modified hollow ceramic microspheres.

[0061] The bottom slurry spraying process parameters are: spraying pressure 0.34MPa, spraying distance 24cm, thickness 1.15mm.

[0062] S4, spray the pattern layer slurry and the transparent protective layer slurry on the bottom slurry in sequence, and then cure the sprayed plate in steps, the curing temperature is first kept at 58°C for 1.4 hours, then kept at 78°C for 2.3 hours, and finally kept at 118°C for 0.6 hours. The cured plate is surface treated, including sanding and polishing, to obtain a lightweight artificial granite plate.

[0063] Comparative Example 1 This comparative example provides a preparation process of a lightweight artificial granite slab, which is different from Example 1 in that no biomass-modified phenolic prepolymer is used in the bottom slurry.

[0064] S1. Use a granite plate as the substrate, use a high-pressure air gun with an air pressure of 0.5 MPa to remove surface dust, then use isopropyl alcohol to wipe and degrease the surface of the substrate, and dry it at 25°C for 30 minutes.

[0065] S2. Apply primer with a coating amount of 150g / m² and pre-dry at 60°C for 45 minutes to complete substrate pretreatment.

[0066] S3. Spraying a base slurry on the pretreated substrate, the base slurry consisting of the following components: 63 parts of orthophthalic unsaturated polyester resin, 22 parts of modified hollow ceramic microspheres, 3 parts of nano-silicon dioxide, and 2 parts of a curing agent.

[0067] The preparation method of the modified hollow ceramic microspheres is as follows: the hollow ceramic microspheres are dried at 105°C for 12 hours, placed in a 95% ethanol solution of KH-550 and stirred for 2 hours, the amount of KH-550 used is 2.5%wt of the hollow ceramic microspheres, filtered and dried at 80°C for 4 hours to obtain modified hollow ceramic microspheres.

[0068] The bottom slurry spraying process parameters are: spraying pressure 0.35MPa, spraying distance 25cm, thickness 1.2mm.

[0069] S4, spraying the pattern layer slurry and the transparent protective layer slurry on the bottom slurry in sequence, and then curing the sprayed plate in steps, the curing temperature is first maintained at 60°C for 1 hour, then maintained at 80°C for 2 hours, and finally maintained at 120°C for 0.5 hour. The cured plate is surface treated, including sanding and polishing, to obtain an artificial granite plate.

[0070] Comparative Example 2 This comparative example provides a preparation process of a lightweight artificial granite slab, which is different from Example 2 in that unmodified ordinary hollow ceramic microspheres are used in the bottom slurry instead of modified hollow ceramic microspheres.

[0071] S1. Use a granite plate as the substrate, use a high-pressure air gun with an air pressure of 0.6 MPa to remove surface dust, then use isopropyl alcohol to wipe and degrease the surface of the substrate, and dry it at 24°C for 25 minutes.

[0072] S2. Apply primer with a primer coating amount of 145g / m² and pre-dry at 58°C for 42 minutes to complete substrate pretreatment.

[0073] S3. Spraying a base slurry on the pretreated substrate, the base slurry consisting of the following components: 40 parts of ortho-phthalic unsaturated polyester resin, 15 parts of biomass-modified phenolic prepolymer, 25 parts of ordinary hollow ceramic microspheres, 4 parts of nano-silicon dioxide, and 3 parts of curing agent.

[0074] The preparation method of the biomass-modified phenolic prepolymer is as follows: enzymatically hydrolyzed lignin and phenol are mixed in a mass ratio of 1:5, a formaldehyde solution with a concentration of 37wt% is added, the molar ratio of phenol to formaldehyde is 1:1.8, the reaction temperature is controlled at 83°C under the condition of pH=9.3, the reaction is carried out for 2 hours, the temperature is lowered to 25°C, the pH is adjusted to 7.0 with dilute hydrochloric acid, and water is removed by vacuum rotary evaporation to obtain the biomass-modified phenolic prepolymer.

[0075] The bottom slurry spraying process parameters are: spraying pressure 0.32MPa, spraying distance 23cm, thickness 1.1mm.

[0076] S4, spraying the pattern layer slurry and the transparent protective layer slurry on the bottom slurry in sequence, and then curing the sprayed plate in steps, the curing temperature is first maintained at 55°C for 1.5 hours, then maintained at 75°C for 2.5 hours, and finally maintained at 115°C for 0.8 hours. The cured plate is surface treated, including sanding and polishing, to obtain an artificial granite plate.

[0077] Performance Testing The artificial granite slabs prepared in the examples and comparative examples were selected as samples for performance testing.

[0078] 1. Density test: Test according to GB / T1463-2005 standard, cut the sample into test blocks of 50mm×50mm×20mm, measure its volume and mass, and calculate the density value.

[0079] 2. Compressive strength test: The test was conducted in accordance with GB / T 1941-2009 standard. The sample was processed into a cube of 100mm×100mm×100mm and tested on a universal material testing machine with a loading rate of 1.0mm / min. The maximum compression load was recorded and the compressive strength was calculated.

[0080] 3. Flexural strength test: According to GB / T 17671-1999 standard, prepare a 160mm×40mm×40mm specimen, use a three-point bending test method on a universal material testing machine, with a loading rate of 0.5mm / min, measure the maximum flexural load of the specimen, and calculate the flexural strength.

[0081] 4. Wear resistance test: According to GB / T 9966.1-2001 standard, use an abrasion tester to test the wear resistance of the sample and measure the wear thickness after 1000 revolutions.

[0082] 5. Water absorption test: According to GB / T 23266-2009 standard, dry the sample at 105°C to constant weight, measure the dry mass, then soak it in water for 48 hours, take it out, wipe the surface dry and weigh it, and calculate the water absorption.

[0083] 6. Freeze-thaw resistance test: According to GB / T 2419-2005 standard, soak the sample in water for 24 hours, then freeze it in a -20℃ environment for 4 hours, and then thaw it in 20℃ water for 4 hours. Repeat 25 cycles and test the strength loss rate of the sample.

[0084] Test data Table 1. Mechanical properties test results

[0085] Table 2. Durability test results

[0086] Data analysis As can be seen from Table 1, the density range of Examples 1-5 is between 1945 and 2010 kg / m³, which achieves a significant weight reduction effect compared with natural granite. At the same time, the compressive strength of the examples is 63.5-68.2 MPa, and the flexural strength is 27.2-29.6 MPa. Although the compressive strength is lower than that of natural granite, the flexural strength is about 80% to 97% higher than that of natural granite, which is particularly important for plate applications. Comparative Example 1 lacks biomass-modified phenolic prepolymer, resulting in a decrease in the elastic modulus of the material, and Comparative Example 2 uses unmodified hollow ceramic microspheres, resulting in poor slurry interface bonding.

[0087] As can be seen from Table 2, the mass change rate of Examples 1-5 before and after water absorption is only 0.15% to 0.17%, which is lower than that of natural granite and comparative samples, indicating that the material has good waterproof performance. In terms of water resistance, the mass change rate of the embodiment is 0.12% to 0.17%, which is significantly lower than that of the comparative example, indicating that the material has excellent stability in a humid environment. The wear resistance test shows that the wear thickness of the embodiment is 0.025-0.030mm, slightly higher than that of natural granite, but much better than that of the comparative sample. In the freeze-thaw resistance test, the strength loss rate of the embodiment is only 2.2% to 2.8%, close to that of natural granite, while the strength loss rate of the comparative sample is as high as 5.6% and 7.8%, indicating that the material of the present invention has excellent freeze-thaw cycle resistance. The introduction of biomass-modified phenolic prepolymer significantly improves the toughness and environmental resistance of the material, while the use of modified hollow ceramic microspheres enhances the compatibility of the slurry and microsphere interface and improves the overall performance of the composite material.

[0088] In summary, the present invention successfully prepared an artificial granite slab with light weight, high strength and excellent durability through the synergistic effect of substrate pretreatment, biomass-modified phenolic prepolymer and modified hollow ceramic microspheres. Compared with natural granite, the density is reduced by more than 35%, the flexural strength is increased by more than 80%, and the durability is not inferior to that of natural granite.

[0089] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that all equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A process for preparing a lightweight artificial granite slab, characterized in that: The following steps are involved: S1, pre-treating the substrate; S2, spraying the bottom slurry on the pretreated substrate; S3, spraying the pattern layer slurry and the transparent protective layer slurry on the bottom slurry; S4, curing the sprayed plate in steps, and performing surface treatment on the cured plate to obtain a lightweight artificial granite plate.

2. The process for preparing the lightweight artificial granite slab according to claim 1, characterized in that: The bottom slurry is composed of the following components: 40-50 parts of unsaturated polyester resin, 15-20 parts of biomass modified phenolic prepolymer, 20-25 parts of modified hollow ceramic microspheres, 2-4 parts of nano silicon dioxide, and 1-3 parts of curing agent.

3. The process for preparing the lightweight artificial granite slab according to claim 2, characterized in that: The preparation method of the modified hollow ceramic microspheres is as follows: drying the hollow ceramic microspheres at 100-110° C. for 10-14 hours, placing them in a 95% ethanol solution of KH-550 and stirring them for 1.5-2.5 hours, filtering them and drying them at 70-85° C. for 3-5 hours to obtain the modified hollow ceramic microspheres.

4. The process for preparing the lightweight artificial granite slab according to claim 2, characterized in that: The preparation method of the biomass-modified phenolic prepolymer comprises the following steps: enzymatically hydrolyzed lignin and phenol are mixed at a mass ratio of 1:5, a formaldehyde solution with a concentration of 37 wt% is added, the reaction temperature is controlled at 83-87°C under the condition of pH=9.3-9.7, the reaction is carried out for 2-3 hours, the temperature is lowered to 25°C, the pH is adjusted to 6.5-7.0 with dilute hydrochloric acid, and water is removed by vacuum rotary evaporation to obtain the biomass-modified phenolic prepolymer.

5. The process for preparing the lightweight artificial granite slab according to claim 3, characterized in that: The amount of KH-550 used is 2% to 3%wt of the hollow ceramic microspheres.

6. The process for preparing the lightweight artificial granite slab according to claim 4, characterized in that: The molar ratio of phenol to formaldehyde is 1:1.

8.

7. The process for preparing the lightweight artificial granite slab according to claim 1, characterized in that: The spraying process parameters of step S2 are: spraying pressure of 0.32-0.38 MPa, spraying distance of 23-27 cm, and thickness of 1.1-1.3 mm.

8. The process for preparing the lightweight artificial granite slab according to claim 2, characterized in that: The unsaturated polyester resin is an orthophthalic unsaturated polyester resin with a molecular weight ranging from 2200 to 2800 g / mol.

9. The process for preparing the lightweight artificial granite slab according to claim 1, characterized in that: The substrate pretreatment in step S1 includes: Granite slabs were selected as substrates. The surface dust was removed with a high-pressure air gun. The surface was wiped and degreased with isopropyl alcohol. The surface was dried at room temperature for 20 to 40 minutes. The primer was applied with a primer coating amount of 140 to 160 g / m 2 , pre-dry at 55~65℃ for 40~50 minutes.

10. A lightweight artificial granite slab obtained by the preparation process according to any one of claims 1 to 9.

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