An unsaturated resin composition for artificial stone and a preparation method thereof

Abstract

The present invention relates to the field of unsaturated resin compositions, and discloses an unsaturated resin composition for artificial stone and a preparation method thereof. The unsaturated resin composition includes: an unsaturated resin, a modified additive, maleic anhydride, and a curing agent; the unsaturated resin includes an unsaturated polyester and a polymerizable monomer, the unsaturated polyester is a polymerization product of a polybasic acid and a polyhydric alcohol, and the polymerizable monomer includes a styrene-based monomer; the modified additive is obtained by grafting modified lignin and octadecyltrichlorosilane on the surface of nano-titanium dioxide, and the modified lignin is prepared by grafting reaction of oxidized lignin with p-phenylenediamine and DOPO, and then further grafting with p-phthalaldehyde, γ-aminopropyltriethoxysilane and DOPO. The present invention adds a modified additive and maleic anhydride to the unsaturated resin-based material to improve the appearance yellowing and water resistance and flame retardancy problems of the material, inhibit defects such as performance aging and mechanical property decline, and effectively extend the service life of artificial stone.

Description

Technical Field

[0001] The present invention belongs to the technical field of unsaturated resin compositions, and particularly relates to an unsaturated resin composition for artificial stone and a preparation method thereof. Background Art

[0002] Artificial stone is a practical building material using polymers. Its manufacturing process is a chemical material reaction process. It is a new type of environmentally friendly composite material that has emerged and been continuously improved with the progress of social science and technology. It is mainly applied in the building decoration industry. Compared with traditional building materials such as stainless steel and ceramics, artificial stone not only has diverse functions and rich colors, but also has a wider application range. Artificial stone is made by mixing unsaturated polyester resin with fillers and pigments through a certain processing procedure. Artificial stone has the advantages of being non-toxic, easy to cut and process, having colors that can be arbitrarily blended, and shapes that can be arbitrarily cast.

[0003] Unsaturated polyester resin is a linear polymer compound condensed from dihydric alcohol and unsaturated dibasic carboxylic acid (anhydride). It has the characteristics of low price, simple production process, high transparency, etc. Its application in the field of life is becoming more and more extensive. However, the waterproofness and heat resistance of unsaturated polyester resin are not prominent. Improving its toughness and flame retardancy is also the current research focus. In addition, since unsaturated polyester resin is a linear polymer compound containing ester bonds and generally contains a large number of benzene rings, long-term exposure to ultraviolet light will cause the aromatic structure therein to transform into a dark quinoid structure, resulting in yellowing and aging of the product, affecting the appearance and service life. Summary of the Invention

[0004] To solve the deficiencies mentioned in the above background art, the purpose of the present invention is to provide an unsaturated resin composition for artificial stone and a preparation method thereof, adding modified additives and maleic anhydride to the unsaturated resin-based material to improve the problems of yellowing of the appearance and water resistance and flame retardancy of the unsaturated resin-based material, inhibiting defects such as performance aging and decline in mechanical properties of the unsaturated resin-based material, and effectively extending the service life of artificial stone.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] An unsaturated resin composition for artificial stone, comprising the following raw materials in parts by weight: 50 - 70 parts of unsaturated resin, 10 - 20 parts of modified additive, 5 - 15 parts of maleic anhydride, and 2 - 5 parts of curing agent; the unsaturated resin includes unsaturated polyester and polymerizable monomer, the unsaturated polyester is a polymerization product of polybasic acid and polyhydric alcohol, and the polymerizable monomer includes styrene-based monomer; the modified additive is obtained by grafting modified lignin and octadecyltrichlorosilane on the surface of nano-titanium dioxide through chemical reaction, wherein the modified lignin is prepared by grafting reaction of oxidized lignin with p-phenylenediamine and DOPO, and then further grafting with p-phthalaldehyde, γ-aminopropyltriethoxysilane and DOPO.

[0007] Preferably, the curing agent is tert-butyl peroxy-2-ethylhexanoate.

[0008] Preferably, the preparation method of the unsaturated resin comprises the following steps: Take phthalic acid, maleic anhydride and propylene glycol in a reactor, heat up to 95 - 105 °C, start stirring for polycondensation reaction after the raw materials are dissolved, initially heat up to 155 - 170 °C and keep the temperature constant for 20 - 30 min, then heat up again to 205 - 210 °C and keep the temperature constant for reaction for 2 - 3 h, then carry out dilution and cooling. When the temperature drops to 175 - 185 °C, add the inhibitor hydroquinone, continue stirring and cooling until the temperature drops to 120 - 125 °C, then add styrene, and then quickly stir until the temperature drops to 55 - 65 °C to obtain the unsaturated resin.

[0009] Preferably, the molar ratio of phthalic acid, maleic anhydride and propylene glycol is 1 - 1.5:1 - 1.5:2 - 3.

[0010] Preferably, the heating rate of the initial heating is 8 - 10 °C / h, and the heating rate of the re-heating is 10 - 12 °C / h.

[0011] Preferably, the preparation method of the modified additive comprises the following steps:

[0012] A. Take sulfate lignin in a reactor, add sodium hydroxide solvent, hydrogen peroxide oxidant and molybdenum trioxide catalyst, react at 65 - 75 °C for 3 - 5 h, then adjust the pH value of the system to 2 - 3 with dilute hydrochloric acid, continue to react at 75 - 85 °C for 20 - 30 min, and after the reaction is completed, carry out suction filtration, washing and drying to obtain oxidized lignin;

[0013] B. Take oxidized lignin, p-phenylenediamine and DOPO in a reactor, add ethanol solvent, react at 70 - 85 °C for 5 - 15 min, and after the reaction is completed, carry out suction filtration, washing and drying to obtain functionalized lignin;

[0014] C. Take functionalized lignin, terephthalaldehyde, and γ-aminopropyltriethoxysilane in a reactor, add ethanol solvent, reflux at 55-70 °C for 4-6 h. After dissolving DOPO in ethanol, add it to the reactor and continue to react at 70-85 °C for 5-7 h. After the reaction is completed, filter, wash, and dry to prepare modified lignin.

[0015] D. Take nano-titanium dioxide and add it to anhydrous ethanol for ultrasonic dispersion to obtain a suspension. Mix modified lignin and deionized water evenly, stir and react at 65-75 °C for 0.5-1 h to obtain a hydrolysis solution. Put the suspension, hydrolysis solution, and octadecyltrichlorosilane into a reactor, adjust the pH value of the system to 4-5 with dilute hydrochloric acid, and then continue to stir and react at 65-75 °C for 2-4 h. After the reaction is completed, filter, wash, and dry to prepare the modified additive.

[0016] Preferably, in step B, the mass ratio of oxidized lignin, p-phenylenediamine, and DOPO is 1-1.4:1:2-2.5.

[0017] Preferably, in step C, the mass ratio of functionalized lignin, terephthalaldehyde, γ-aminopropyltriethoxysilane, and DOPO is 2-3:1.3-2:1.2-1.7:3-3.5.

[0018] Preferably, in step D, the mass ratio of nano-titanium dioxide, modified lignin, and octadecyltrichlorosilane is 3-5:2-5:4-6.

[0019] The preparation method of the unsaturated resin composition for artificial stone as described above includes the following steps: Take parts by weight of unsaturated resin, modified additive, and maleic anhydride and heat at 65-80 °C to melt maleic anhydride, then stir until cooled to room temperature, and then add parts by weight of curing agent, stir evenly, pour into a mold, cure at 55-65 °C for 0.5-1 h, and then raise the temperature to 80-85 °C and continue to cure for 1-1.5 h to prepare the unsaturated resin composition for artificial stone.

[0020] The beneficial effects of the present invention:

[0021] The present invention uses sulfate lignin as a raw material, improves the content of carbonyl groups in lignin through an oxidation reaction, and reacts the carbonyl in the oxidized lignin structure with the amino group at one end of p-phenylenediamine and the P-H bond in the DOPO structure to prepare a nitrogen and phosphorus modified functional lignin, thereby grafting the antioxidant p-phenylenediamine and the flame retardant DOPO onto the lignin surface to inhibit the aging decomposition and yellowing of unsaturated resin-based materials, and at the same time endowing the unsaturated resin-based materials with good flame retardant properties. Then, the functional lignin, terephthalaldehyde, and γ-aminopropyltriethoxysilane are reacted, so that the aldehyde groups at both ends of terephthalaldehyde react with the amino group in the functional lignin structure and the amino group in the γ-aminopropyltriethoxysilane structure respectively to generate two CH=N groups, and further graft DOPO to undergo an addition reaction to prepare a modified lignin, which is beneficial to the dispersion of lignin in unsaturated resin-based materials, further improving the mechanical properties and flame retardant properties of the matrix. At the same time, in the present invention, the silanol groups in the modified lignin and octadecyltrichlorosilane structure undergo a condensation reaction with the hydroxyl groups on the surface of nano-titanium dioxide to prepare a modified additive. Among them, nano-titanium dioxide is used as an inorganic ultraviolet shielding agent with good weather resistance and heat resistance, and due to its special photocatalytic activity, it has strong antibacterial and bactericidal abilities after absorbing ultraviolet light energy. And octadecyltrichlorosilane has a long hydrophobic chain structure. Grafting the modified lignin and octadecyltrichlorosilane onto the surface of nano-titanium dioxide is beneficial to the dispersion of nano-titanium dioxide, enabling its mechanical properties and ultraviolet light aging resistance to be fully exerted, and at the same time endowing the unsaturated resin-based materials with excellent waterproof and stain-resistant properties. The present invention adds the modified additive to the unsaturated resin-based materials to improve the appearance yellowing and water resistance and flame retardancy problems of the unsaturated resin-based materials, inhibit defects such as the performance aging and mechanical property degradation of the unsaturated resin-based materials, and effectively extend the service life of artificial stone. Specific Embodiments

[0022] The following will describe clearly and completely the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0023] Example 1 A preparation method of an unsaturated resin includes the following steps:

[0024] Measure phthalic acid, maleic anhydride and propylene glycol in a molar ratio of 1:1:2.15 and place them in a reactor. Heat up to 100 °C. After the raw materials are dissolved, start stirring for polycondensation reaction. Initially heat up to 160 °C and keep it at a constant temperature for 30 min with a heating rate of 10 °C / h. Then heat up again to 210 °C and keep it at a constant temperature for 3 h with a heating rate of 12 °C / h. Subsequently, carry out dilution and cooling. When the temperature drops to 180 °C, add 18 mg of polymerization inhibitor hydroquinone. Keep stirring and cool down to 120 °C, then add 60 mL of styrene. Subsequently, stir rapidly until the temperature drops to 60 °C to obtain unsaturated resin.

[0025] Example 2 A preparation method of a modified additive comprises the following steps:

[0026] A. Take 3.2 g of sulfate lignin and place it in a reactor. Add 10 mL of 2.5 wt% sodium hydroxide solvent, 15 mL of hydrogen peroxide oxidant and 0.15 g of molybdenum trioxide catalyst. React at 70 °C for 4 h. Then adjust the pH value of the system to 2 with dilute hydrochloric acid and continue to react at 80 °C for 30 min. After the reaction is completed, carry out suction filtration, washing and drying to obtain oxidized lignin.

[0027] B. Take 2.5 g of oxidized lignin, 2 g of p-phenylenediamine and 4.5 g of DOPO and place them in a reactor. Add 50 mL of ethanol solvent and react at 75 °C for 10 min. After the reaction is completed, carry out suction filtration, washing and drying to obtain functionalized lignin.

[0028] C. Take 3 g of functionalized lignin, 1.6 g of terephthalaldehyde and 1.5 g of γ-aminopropyltriethoxysilane and place them in a reactor. Add 50 mL of ethanol solvent and reflux at 60 °C for 5 h. Take 3 g of DOPO dissolved in 20 mL of ethanol and add it to the reactor, then continue to react at 80 °C for 6 h. After the reaction is completed, carry out suction filtration, washing and drying to obtain modified lignin.

[0029] D. Take 3 g of nano-titanium dioxide and add it to 100 mL of absolute ethanol for ultrasonic dispersion to obtain a suspension. Take 2 g of modified lignin and 30 mL of deionized water and mix them evenly. Stir and react at 70 °C for 1 h to obtain a hydrolysis solution. Put the suspension, the hydrolysis solution and 4.8 g of octadecyltrichlorosilane into a reactor. Adjust the pH value of the system to 4 with dilute hydrochloric acid, then continue to stir and react at 70 °C for 4 h. After the reaction is completed, carry out suction filtration, washing and drying to obtain the modified additive.

[0030] Example 3 An unsaturated resin composition for artificial stone comprises the following raw materials in parts by weight:

[0031] 55 parts of the unsaturated resin prepared in Example 1, 12 parts of the modified additive prepared in Example 2, 7 parts of maleic anhydride, and 2 parts of curing agent tert-butyl peroxy-2-ethylhexanoate.

[0032] The preparation method of the above unsaturated resin composition for artificial stone comprises the following steps:

[0033] Take parts by weight of unsaturated resin, modified additive and maleic anhydride, heat at 70 °C to melt maleic anhydride, then stir until cooled to room temperature, then add parts by weight of curing agent thereto, stir evenly, pour into a mold, cure at 60 °C for 0.5 h, then raise the temperature to 85 °C and continue to cure for 1 h to prepare an unsaturated resin composition for artificial stone.

[0034] Example 4 An unsaturated resin composition for artificial stone, comprising the following raw materials in parts by weight:

[0035] 62 parts of the unsaturated resin prepared in Example 1, 15 parts of the modified additive prepared in Example 2, 10 parts of maleic anhydride, 4 parts of tert-butyl peroxy-2-ethylhexanoate as the curing agent.

[0036] The preparation method of the above unsaturated resin composition for artificial stone is the same as that in Example 3.

[0037] Example 5 An unsaturated resin composition for artificial stone, comprising the following raw materials in parts by weight:

[0038] 70 parts of the unsaturated resin prepared in Example 1, 18 parts of the modified additive prepared in Example 2, 14 parts of maleic anhydride, 5 parts of tert-butyl peroxy-2-ethylhexanoate as the curing agent.

[0039] The preparation method of the above unsaturated resin composition for artificial stone is the same as that in Example 3.

[0040] Comparative Example 1 The preparation method of a modified additive comprises the following steps:

[0041] A. Take 3.2 g of sulfate lignin in a reactor, add 10 mL of 2.5 wt% sodium hydroxide solvent, 15 mL of hydrogen peroxide oxidant and 0.15 g of molybdenum trioxide catalyst, react at 70 °C for 4 h, then adjust the pH value of the system to 2 with dilute hydrochloric acid, continue to react at 80 °C for 30 min, and after the reaction is completed, carry out suction filtration, washing and drying to prepare oxidized lignin;

[0042] B. Take 2.5 g of oxidized lignin, 2 g of p-phenylenediamine and 4.5 g of DOPO in a reactor, add 50 mL of ethanol solvent, react at 75 °C for 10 min, and after the reaction is completed, carry out suction filtration, washing and drying to prepare the modified additive.

[0043] Comparative Example 2 The preparation method of a modified additive comprises the following steps:

[0044] A. Take 3.2 g of sulfate lignin in a reactor, add 10 mL of 2.5 wt% sodium hydroxide solvent, 15 mL of hydrogen peroxide oxidant, and 0.15 g of molybdenum trioxide catalyst. Place it at 70 °C for reaction for 4 h. Then adjust the pH value of the system to 2 with dilute hydrochloric acid, and continue to place it at 80 °C for reaction for 30 min. After the reaction is completed, filter, wash, and dry to prepare oxidized lignin;

[0045] B. Take 2.5 g of oxidized lignin, 2 g of p-phenylenediamine, and 4.5 g of DOPO in a reactor, add 50 mL of ethanol solvent, and place it at 75 °C for reaction for 10 min. After the reaction is completed, filter, wash, and dry to prepare functionalized lignin;

[0046] C. Take 3 g of functionalized lignin, 1.6 g of p-phthalaldehyde, and 1.5 g of γ-aminopropyltriethoxysilane in a reactor, add 50 mL of ethanol solvent, and reflux at 60 °C for reaction for 5 h. Take 3 g of DOPO dissolved in 20 mL of ethanol and add it to the reactor, and continue to react at 80 °C for 6 h. After the reaction is completed, filter, wash, and dry to prepare a modified additive.

[0047] Comparative Example 3 An unsaturated resin composition for artificial stone, comprising the following raw materials in parts by weight:

[0048] 70 parts of the unsaturated resin prepared in Example 1, 18 parts of the modified additive prepared in Comparative Example 1, 14 parts of maleic anhydride, and 5 parts of the curing agent tert-butyl peroxy-2-ethylhexanoate.

[0049] The preparation method of the above unsaturated resin composition for artificial stone is the same as that in Example 3.

[0050] Comparative Example 4 An unsaturated resin composition for artificial stone, comprising the following raw materials in parts by weight:

[0051] 70 parts of the unsaturated resin prepared in Example 1, 9 parts of the modified additive prepared in Comparative Example 2, 9 parts of nano-titanium dioxide, 14 parts of maleic anhydride, and 5 parts of the curing agent tert-butyl peroxy-2-ethylhexanoate.

[0052] The preparation method of the above unsaturated resin composition for artificial stone is the same as that in Example 3.

[0053] Comparative Example 5 An unsaturated resin composition for artificial stone, comprising the following raw materials in parts by weight:

[0054] 70 parts of the unsaturated resin prepared in Example 1, 9 parts of lignin, 9 parts of nano-titanium dioxide, 14 parts of maleic anhydride, and 5 parts of the curing agent tert-butyl peroxy-2-ethylhexanoate.

[0055] The preparation method of the above unsaturated resin composition for artificial stone is the same as that in Example 3.

[0056] Performance detection

[0057] The unsaturated resin compositions prepared in Examples 3-5 and Comparative Examples 3-5 were subjected to performance detection:

[0058] (1) Tests on mechanical properties and flame retardancy: For the tensile strength, dumbbell-shaped tensile specimens were prepared according to GB / T 1040.2, and the tensile rate was 50 mm / min; for the impact strength, rectangular specimens were prepared according to GB / T 1843-2008, and a cantilever beam pendulum impact testing machine was used for testing; for the flexural property, rectangular specimens were prepared according to GB / T 9341-2008, and a universal testing machine was used with a test speed of 30 mm / min; the flame retardancy of the samples was tested according to the limiting oxygen index, and the data results are shown in Table 1.

[0059] Table 1 Test results of the mechanical properties and flame retardancy of the samples

[0060]

[0061] It can be seen from the data in Table 1 that the unsaturated resin compositions prepared in Examples 3-5 of the present invention have high tensile strength, flexural strength, impact strength and limiting oxygen index, and have good mechanical properties and flame retardancy. Among them, in Comparative Example 3, the modified additive component only carried out the grafting reaction of oxidized lignin, p-phenylenediamine and DOPO, and its measured mechanical properties and flame retardancy were worse than those in Examples 3-5. The reason is that DOPO and nano-titanium dioxide were not further grafted. In Comparative Example 4, the modified additive component was simply mixed with nano-titanium dioxide, and its measured tensile strength, flexural strength and impact strength were lower than those in Examples 3-5. The reason may be that the agglomeration of nano-titanium dioxide led to the reduction of its mechanical properties. In Comparative Example 5, lignin and nano-titanium dioxide were simply mixed. Since the flame retardant component was not grafted and lignin and nano-titanium dioxide were not evenly dispersed in the matrix, its measured mechanical properties and flame retardancy were significantly lower than those in Examples 3-5.

[0062] (2) Test on heat-oxygen aging resistance: Referring to GB / T 7141-2008, an accelerated heat-oxygen aging experiment was carried out in a constant temperature forced-air drying oven at 150 °C. The specimens were taken out at different time intervals, cooled and then tested. According to HG / T 3862-2006, a full-automatic color difference meter was used to calculate the yellow index, and the data results are shown in Table 2.

[0063] (3) Test on ultraviolet light aging resistance: The specimens were placed in an ultraviolet aging test chamber, and 4 UV340-type ultraviolet lamp tubes with a power of 40 W each were used. The specimens were taken out at intervals for testing. According to HG / T 3862-2006, a full-automatic color difference meter was used to calculate the yellow index, and the data results are shown in Table 2.

[0064] (4) Water absorption rate test: Unsaturated resin composition was taken and distilled water was added. Experiments were carried out using a constant temperature water bath at 20 °C, 60 °C, and 100 °C. It was denoted as M1 before soaking in water and M2 after soaking in water. After completion, the water absorption rate K after soaking for 12 h was calculated, K = [(M2 - M1) / M1] × 100%. The smaller K is, the more water-resistant the resin is; the larger K is, the stronger the water absorption ability. The data results are shown in Table 2.

[0065] Table 2 Test results of yellowing resistance and waterproof performance of samples

[0066]

[0067]

[0068] It can be seen from the data in Table 2 that the unsaturated resin compositions prepared in Examples 3 - 5 of the present invention have better yellowing resistance and water resistance than those in Comparative Examples 3 - 5. Among them, the measured ultraviolet aging yellow index and water absorption rate in Comparative Examples 3 - 4 are higher than those in Examples 3 - 5. The reason is that the modified additive component did not introduce nano-titanium dioxide or only simply mixed with nano-titanium dioxide, and the hydrophobic long chain was not introduced, resulting in a decrease in its ultraviolet yellowing resistance and water resistance compared with Examples 3 - 5. The measured thermal oxygen aging yellow index, ultraviolet aging yellow index, and water absorption rate in Comparative Example 5 are higher than those in Examples 3 - 5. The reason is that only lignin and nano-titanium dioxide were simply mixed, and the antioxidant p-phenylenediamine and the hydrophobic long chain were not grafted, resulting in a decrease in its yellowing resistance and water resistance.

[0069] In the description of this specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0070] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. An unsaturated resin composition for artificial stone, characterized in that: The invention comprises the following raw materials in parts by weight: 50-70 parts of unsaturated resin, 10-20 parts of modified additive, 5-15 parts of maleic anhydride and 2-5 parts of curing agent; the unsaturated resin comprises unsaturated polyester and polymerizable monomer, the unsaturated polyester is a polymerization product of polyacid and polyol, and the polymerizable monomer comprises styrene monomer; the modified additive is obtained by grafting modified lignin and octadecyl trichlorosilane on the surface of nano titanium dioxide by chemical reaction, wherein the modified lignin is obtained by grafting oxidized lignin with p-phenylenediamine and DOPO by chemical reaction, and then further grafting with terephthalaldehyde, γ-aminopropyltriethoxysilane and DOPO; The preparation method of the modified additive comprises the following steps: A. Put kraft lignin in a reactor, add sodium hydroxide solvent, hydrogen peroxide hydrogenation agent and molybdenum trioxide catalyst, react at 65-75°C for 3-5h, then adjust the pH value of the system to 2-3 with dilute hydrochloric acid, continue to react at 75-85°C for 20-30min, and after the reaction is completed, filter, wash and dry to prepare oxidized lignin; B. Put oxidized lignin, p-phenylenediamine and DOPO in a reactor, add ethanol solvent, and react at 70-85°C for 5-15 minutes. After the reaction is completed, filter, wash and dry to prepare functionalized lignin. C. Take the functionalized lignin, terephthalaldehyde and γ-aminopropyltriethoxysilane in a reactor, add ethanol solvent, place it under reflux reaction at 55-70°C for 4-6 hours, take DOPO dissolved in ethanol and add it to the reactor, place it under 70-85°C for further reaction for 5-7 hours, and after the reaction is completed, filter, wash and dry to prepare modified lignin; D. Take nano titanium dioxide and add anhydrous ethanol for ultrasonic dispersion to obtain a suspension, take modified lignin and deionized water and mix them evenly, place them at 65-75°C with stirring for 0.5-1h to obtain a hydrolyzate, put the suspension, hydrolyzate and octadecyltrichlorosilane into a reactor, adjust the pH value of the system to 4-5 with dilute hydrochloric acid, and then place them at 65-75°C for continuous stirring for 2-4h. After the reaction is completed, filter, wash and dry to prepare a modified additive.

2. The unsaturated resin composition for artificial stone according to claim 1, characterized in that: The curing agent is tert-butyl peroxide-2-ethylhexanoate.

3. The unsaturated resin composition for artificial stone according to claim 1, characterized in that: The preparation method of the unsaturated resin comprises the following steps: taking phthalic acid, maleic anhydride and propylene glycol in a reactor, heating to 95-105° C., stirring to carry out polycondensation reaction after the raw materials are dissolved, initially heating to 155-170° C. and keeping the temperature constant for 20-30 minutes, heating again to 205-210° C. and keeping the temperature constant for 2-3 hours, then diluting and cooling, adding a polymerization inhibitor hydroquinone when the temperature drops to 175-185° C., adding styrene when the temperature drops to 120-125° C. with continuous stirring, and then rapidly stirring until the temperature drops to 55-65° C. to prepare the unsaturated resin.

4. The unsaturated resin composition for artificial stone according to claim 3, characterized in that: The molar ratio of phthalic acid, maleic anhydride and propylene glycol is 1-1.5:1-1.5:2-3.

5. The unsaturated resin composition for artificial stone according to claim 3, characterized in that: The heating rate of the initial heating is 8-10°C / h, and the heating rate of the second heating is 10-12°C / h.

6. The unsaturated resin composition for artificial stone according to claim 1, characterized in that: In the step B, the mass ratio of oxidized lignin, p-phenylenediamine and DOPO is 1-1.4:1:2-2.

5.

7. The unsaturated resin composition for artificial stone according to claim 1, characterized in that: In the step C, the mass ratio of the functionalized lignin, terephthalaldehyde, γ-aminopropyltriethoxysilane and DOPO is 2-3:1.3-2:1.2-1.7:3-3.

5.

8. The unsaturated resin composition for artificial stone according to claim 1, characterized in that: In the step D, the mass ratio of nano titanium dioxide, modified lignin and octadecyltrichlorosilane is 3-5:2-5:4-6.

9. A method for preparing an unsaturated resin composition for artificial stone according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: taking parts by weight of an unsaturated resin, a modification additive and maleic anhydride, heating them at 65-80°C to melt the maleic anhydride, stirring them until they are cooled to room temperature, adding parts by weight of a curing agent thereto, stirring them evenly, pouring them into a mold, curing them at 55-65°C for 0.5-1h, then heating them to 80-85°C and continuing curing them for 1-1.5h to prepare an unsaturated resin composition for artificial stone.

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