Coal-based solid waste stone plastic composite master batch and preparation method thereof

Abstract

The application belongs to the field of plastic materials, and discloses a coal-based solid waste stone-plastic composite master batch and a preparation method thereof. The preparation method comprises the following steps: after coal-based solid waste is crushed and calcined and activated, the coal-based solid waste is added into a modified solution containing a boric acid compound and a lignin sulfonate, and heated and stirred to react, so that modified particles are obtained; polyolefin and an acid anhydride compound are mixed and heated to react, so that acid anhydride modified polyolefin is obtained, then an epoxy-based chain extender is added, and heating reaction is continued, so that modified molten liquid is obtained; the modified particles are added into the modified molten liquid for melting and stirring, so that mixed slurry is obtained, then an amine crosslinking agent and an epoxy borate are added, and heating, stirring, extrusion, cooling and granulation are performed, so that the coal-based solid waste stone-plastic composite master batch is obtained. The coal-based solid waste stone-plastic composite master batch prepared by the above method can maintain good toughness while maintaining a high content of coal-based solid waste.

Description

Technical Field

[0001] This application relates to the field of plastic materials, specifically to a coal-based solid waste stone-plastic composite masterbatch and its preparation method. Background Technology

[0002] Coal-based solid waste stone-plastic composite masterbatch is a composite material made by melt blending coal gangue, fly ash, gasification slag, desulfurization ash and other coal-based industrial solid wastes as the main inorganic fillers with thermoplastic resins such as polypropylene, polyethylene and high-density polyethylene. Because it can realize the resource utilization of coal-based solid waste, reduce the production cost of plastic products and improve the rigidity and dimensional stability of materials, it is now widely used in stone-plastic flooring, building decoration panels, pipes and packaging products.

[0003] In existing technologies, to further improve the utilization rate of coal-based solid waste and reduce resin usage, the proportion of inorganic fillers in composite masterbatches is usually increased. However, since coal-based solid waste itself consists of rigid inorganic particles, when the filler content is too high, a large number of inorganic particles will restrict the free movement of polymer molecular chains and weaken the toughness of the continuous resin phase. This leads to a significant increase in stress concentration within the composite material, resulting in increased brittleness of the obtained stone-plastic composite masterbatch. During subsequent extrusion, calendering, or injection molding processes, problems such as cracking, edge chipping, and breakage are likely to occur. At the same time, in low-temperature environments, due to the further decrease in the mobility of polymer molecular chains, the impact resistance of the material will be significantly reduced, making it prone to brittle fracture, which seriously affects the service life and structural stability of the products. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a coal-based solid waste stone-plastic composite masterbatch and its preparation method, aiming to solve the problem of reduced toughness of the composite masterbatch caused by high content of coal-based solid waste in the coal-based solid waste stone-plastic composite masterbatch.

[0005] To address the aforementioned technical problems, a method for preparing coal-based solid waste stone-plastic composite masterbatch is proposed, comprising the following preparation steps: S1. After crushing, calcining and activating the coal-based solid waste, it is added to a modified solution containing boric acid compounds and lignin sulfonate, and heated and stirred to react, thereby obtaining modified particles. S2. Mix polyolefin and acid anhydride compound, heat and react to obtain acid anhydride modified polyolefin, then add epoxy chain extender, continue heating and react to obtain modified melt, wherein the acid anhydride compound contains carbon-carbon double bonds; S3. Add the modified particles to the modified melt and stir to obtain a mixed slurry. Then add amine crosslinking agent and epoxy borate ester, heat and stir to react, extrude, cool and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch.

[0006] In addition, a coal-based solid waste stone-plastic composite masterbatch is proposed, which is prepared by the preparation method of the coal-based solid waste stone-plastic composite masterbatch described above.

[0007] As can be seen from the above technical solutions, the exemplary embodiments disclosed herein possess at least the following advantages and positive effects: On the one hand, by crushing and calcining coal-based solid waste to activate it, the number of active sites on the surface of the coal-based solid waste is increased. Then, boric acid compounds and lignin sulfonates are used to synergistically modify the surface of the coal-based solid waste particles, so that the boron-oxygen structure in the boric acid compounds forms a stable bond with the hydroxyl groups on the surface of the coal-based solid waste. At the same time, the aromatic skeleton and sulfonic acid groups in the lignin sulfonates form a flexible organic coating layer on the particle surface, thereby reducing the tendency of coal-based solid waste particles to agglomerate and improving the interfacial compatibility between coal-based solid waste and polyolefin matrix. Furthermore, by grafting the carbon-carbon double bonds in the anhydride compounds onto the polyolefin molecular chain, polar acids are introduced into the polyolefin matrix. The anhydride group enhances the interfacial bonding between polyolefins and coal-based solid waste. During subsequent melt blending, the amine crosslinking agent promotes interfacial crosslinking. Simultaneously, the borate structure in the epoxy borate ester forms dynamic boron-oxygen bonds with the oxygen-containing groups on the surface of the coal-based solid waste. This constructs a multi-functional synergistic network structure between the coal-based solid waste particles and the polyolefin matrix, which combines interfacial bonding and dynamic energy dissipation. This solves the problems of weak interfacial bonding, severe stress concentration, and increased material brittleness caused by the large amount of inorganic particles filling the matrix. As a result, it achieves uniform stress transmission and dissipation under external force, significantly improving the impact toughness, crack resistance, and long-term stability of the composite masterbatch.

[0008] On the other hand, by adding epoxy chain extenders during the reaction of polyolefins and acid anhydride compounds, the epoxy groups in the epoxy chain extenders undergo ring-opening addition reactions with the free radical chain ends generated by β-chain scission during the grafting process of polyolefins. This repairs the molecular chain breakage defects of polyolefins during high-temperature grafting, improves the molecular weight, molecular chain entanglement degree and melt strength of polyolefins, and avoids the problem of decreased melt processing performance due to degradation and chain breakage of polyolefins. This solves the problems of melt fracture and extrusion instability that are prone to occur in the traditional high-filling coal-based solid waste stone-plastic system during production, thereby improving the processing stability, melt flow performance and continuous production adaptability of composite masterbatch under high-filling conditions. Attached Figure Description

[0009] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 This is a schematic diagram of a method for preparing coal-based solid waste stone-plastic composite masterbatch in one embodiment; Figure 2 This is a schematic diagram of step S1 in a method for preparing coal-based solid waste stone-plastic composite masterbatch in one embodiment; Figure 3 This is a schematic diagram of step S2 in the preparation method of coal-based solid waste stone-plastic composite masterbatch in one embodiment; Figure 4 This is a schematic diagram of step S3 in the preparation method of coal-based solid waste stone-plastic composite masterbatch in one embodiment. Detailed Implementation

[0010] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art.

[0011] Furthermore, the described features or characteristics may be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure may be practiced without one or more of the specific details, or other methods, steps, etc. may be employed. In other instances, well-known methods, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0012] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0013] Please refer to Figure 1 This invention proposes a method for preparing coal-based solid waste stone-plastic composite masterbatch, the preparation method comprising the following steps: S1. After crushing, calcining and activating the coal-based solid waste, it is added to a modified solution containing boric acid compounds and lignin sulfonate, and heated and stirred to react, thereby obtaining modified particles.

[0014] In step S1, the coal-based solid waste includes at least one of coal gangue, fly ash, and gasification slag; the boric acid compound includes at least one of boric acid, borax, sodium metaborate, sodium perborate, or ammonium metaborate; and the lignin sulfonate includes at least one of sodium lignin sulfonate, calcium lignin sulfonate, magnesium lignin sulfonate, ammonium lignin sulfonate, and potassium lignin sulfonate.

[0015] In the modified particles obtained in step S1, the surface of the coal-based solid waste after crushing and calcination activation exposes more silanol, aluminol, and metal oxide active sites. Boric acid compounds can form B-O-Si or B-O-M (M is a metal element) coordination or condensation reactions with the above active sites, thereby improving the interfacial reaction activity and stability of the particle surface. At the same time, the sulfonic acid groups in lignin sulfonate can be adsorbed onto the particle surface through hydrogen bonding, electrostatic adsorption, and metal ion coordination. Its aromatic structure and organic segments form a flexible organic coating layer on the particle surface. This flexible interfacial layer can disperse and buffer interfacial stress when the composite system is under stress, reduce stress concentration and crack propagation tendency, thereby effectively improving the problem of reduced toughness in highly filled coal-based solid waste stone-plastic composite masterbatch, and improving the impact resistance, processing stability, and interfacial bonding strength of the composite system.

[0016] Step S1 includes: S1.1 After crushing the coal-based solid waste, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 450~700℃ for 1~3h to obtain activated particles, wherein the particle size of the coal-based particles is 10~80μm.

[0017] Grinding coal-based solid waste to a particle size range of 10-80 μm through crushing and ball milling, followed by calcination at 450-700℃ for 1-3 hours, can significantly increase the specific surface area and surface active sites of the particles, exposing more silanol, aluminumol, and metal oxide sites, thus providing a reactive interface for subsequent surface modification. At the same time, the calcination activation process can remove some organic impurities and adsorbed water, improve the thermal and chemical stability of the particles, and make the particle surface structure more uniform and open, which is conducive to the adsorption and coordination reactions of boric acid compounds and lignin sulfonates. In addition, a suitable particle size distribution can improve the dispersibility of particles in the polyolefin matrix, reduce local stress concentration, and improve the interfacial bonding strength and overall toughness of the composite masterbatch under high filling conditions.

[0018] S1.2 Add boric acid compound and lignosulfonate to deionized water and stir at 50~70℃ for 20~40 min to obtain modified solution, wherein the concentrations of boric acid compound and lignosulfonate in modified solution are 1~5wt% and 2~8wt%, respectively.

[0019] Boric acid compounds and lignin sulfonates are thoroughly dissolved in deionized water at 50-70℃. This promotes hydrogen bonding and intermolecular synergistic effects between the boron hydroxyl groups in the boronic acid compounds and the sulfonic acid and phenolic hydroxyl groups in the lignin sulfonates, thereby constructing a stable and homogeneous modified system. The boronic acid compounds provide an active boron source for subsequent coordination or condensation reactions with the active hydroxyl groups on the surface of coal-based solid waste, while the lignin sulfonates, with their amphiphilic structure, enhance the dispersion stability of the modified components in the aqueous phase and enable more uniform coating of organic segments onto the particle surface. Simultaneously, controlling the concentration range of boronic acid compounds and lignin sulfonates helps to balance surface activity, interfacial coating capacity, and system flow stability, avoiding localized aggregation or excessive viscosity due to excessive concentration. This improves the uniformity of subsequent surface modification of coal-based solid waste particles and the interfacial construction effect.

[0020] S1.3 Add the activated particles to the modification solution, stir and react at 70~95℃ for 1~3h, filter and dry to obtain modified particles, wherein the mass ratio of activated particles to modification solution is 1:(1.5~4), and the stirring speed is 300~800r / min.

[0021] Adding activated particles to the modification solution and continuously stirring at 70–95°C promotes coordination or condensation reactions between the boron hydroxyl groups in the boric acid compound and the silanol, aluminol, and metal oxygen groups on the surface of the activated particles, forming a stable boron-containing active interface layer on the particle surface. Simultaneously, the sulfonic acid groups in the lignin sulfonate can be stably adsorbed onto the particle surface through hydrogen bonding, electrostatic adsorption, and metal ion coordination. Its aromatic structure and organic segments further form a flexible organic coating layer on the outer layer of the particles, thereby improving the organic affinity and interfacial wetting ability of the particle surface. Furthermore, a suitable ratio of activated particles to the modification solution and a suitable stirring speed can improve the uniformity of contact between the particles and the modified components, promoting more thorough surface coating and interfacial construction, avoiding problems of insufficient local modification or uneven coating, and ultimately improving the interfacial bonding strength, stress transfer ability, and toughness retention under high-filling conditions of the modified particles in the polyolefin system.

[0022] In one embodiment, step S1 further includes: S1.1 After crushing the coal-based solid waste, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 450~700℃ for 1~3h to obtain activated particles, wherein the particle size of the coal-based particles is 10~80μm. S1.2 Add boric acid compound and lignosulfonate to deionized water, stir at 50~70℃ for 20~40 min to obtain modified solution, wherein the concentrations of boric acid compound and lignosulfonate in the modified solution are 1~5wt% and 2~8wt%, respectively; S1.3 Add the activated particles to the modified solution and stir at 70~95℃ for 1~3h to obtain a modified dispersion. The mass ratio of activated particles to modified solution is 1:(1.5~4), and the stirring speed is 300~800r / min. S1.4. After the modified dispersion is cooled to 50~75℃, add the imidazole compound, continue stirring and reacting for 0.5~2h, filter and dry to obtain modified particles. The amount of imidazole compound added is 4~8wt% of the total mass of coal-based solid waste. The imidazole compound includes at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-hexyl-3-methylimidazolium bromide.

[0023] After the addition of imidazole compounds, the imidazole cations undergo polar association with the sulfonic acid groups and aromatic structures in lignin sulfonates through their positively charged imidazole rings. Simultaneously, the lone pair electrons on the imidazole rings can form weak coordination with oxygen atoms in the borate ester layer, thereby forming an ion interface layer with flexible flow characteristics on the surface of coal-based solid waste particles. This interface layer not only further improves the wettability and dispersibility of the particles with the polyolefin matrix, but also provides a deformable buffer space for the composite system, effectively absorbing external stress and reducing interfacial stress concentration. This significantly improves the toughness, impact resistance, and interfacial bonding strength of the highly filled coal-based solid waste stone-plastic composite masterbatch. At the same time, it provides a uniform and active surface environment for subsequent melt blending and chemical crosslinking reactions, which is conducive to the construction of a stable multivalent covalent crosslinking interfacial network.

[0024] S2. Mix polyolefin and acid anhydride compound, heat and react to obtain acid anhydride modified polyolefin, then add epoxy chain extender, continue heating and react to obtain modified melt, wherein the acid anhydride compound contains carbon-carbon double bonds.

[0025] In step S2, the polyolefin includes at least one of polyethylene, polypropylene, and high-density polyethylene; the acid anhydride compound includes at least one of maleic anhydride, itaconic anhydride, and methyltetrahydrophthalic anhydride; the free radical initiator includes at least one of dicumyl peroxide, benzoyl peroxide, and di-tert-butyl peroxide; and the epoxy chain extender includes at least one of glycidyl methacrylate, bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and pentaerythritol glycidyl ether.

[0026] Anhydride compounds are grafted onto polyolefin molecular chains via carbon-carbon double bonds under the action of free radical initiators, transforming the polyolefin from a nonpolar structure into a reactive matrix containing anhydride active groups. This enhances the interfacial interaction between the polyolefin and the borate, hydroxyl, and lignin sulfonate polar groups on the surface of coal-based solid waste. Subsequently, the epoxy groups in the epoxy chain extender further undergo ring-opening addition reactions with the free radical chain ends generated during the β-chain scission process of polyolefin grafting, repairing molecular chain breakage defects, increasing the length of polyolefin molecular chains and the degree of interchain entanglement, and improving the melt strength and plastic deformation capacity of the matrix. At the same time, the formed multifunctional interfacial structure can effectively buffer the modulus difference between particles and polymers, reduce the tendency of interfacial debonding and crack propagation under external forces, and thus significantly improve the toughness, impact resistance, and interfacial stability of high-content coal-based solid waste stone-plastic composite masterbatch.

[0027] Step S2 includes: S2.1 Add polyolefin, acid anhydride compound and free radical initiator to a reaction vessel, heat to 160~210℃ in an inert atmosphere and stir for 30~50 min to obtain acid anhydride modified polyolefin, wherein the mass ratio of polyolefin: acid anhydride compound: free radical initiator is 100:(4~8):(0.05~1), and the stirring speed is 300~1200 r / min.

[0028] Melting polyolefins, anhydride compounds, and free radical initiators under an inert atmosphere effectively prevents oxidative degradation of polyolefins at high temperatures and improves the stability of the grafting reaction. The free radical initiator, upon thermal decomposition, generates active free radical sites, enabling the stable grafting of anhydride compounds containing carbon-carbon double bonds onto the polyolefin molecular chain. This introduces polar functional groups such as anhydride groups into the polyolefin molecular chain, enhancing the interfacial reactivity and polar compatibility of the polyolefin matrix. Simultaneously, a melting reaction temperature of 160–210 °C ensures thorough plasticization of the polyolefin and promotes uniform dispersion of the anhydride. Combined with stirring conditions of 300–1200 r / min, this improves the free radical grafting efficiency and the uniformity of functional group distribution. The result is anhydride-modified polyolefin with good reactivity, interfacial bonding ability, and subsequent chain extension reaction capability, providing a foundation for improving the toughness and interfacial stability of highly filled coal-based solid waste stone-plastic composite masterbatches.

[0029] S2.2 Add epoxy chain extender to anhydride-modified polyolefin, heat to 170~230℃ and stir for 10~20 min to obtain pre-modified melt, wherein the amount of epoxy chain extender added is 1~5wt% of the total amount of polyolefin, and the stirring speed is 200~600r / min.

[0030] When epoxy chain extenders are added to anhydride-modified polyolefins, the epoxy groups can undergo ring-opening addition reactions with the free radical chain ends generated during the β-chain scission process of polyolefin grafting. This increases the length of the polyolefin molecular chain and the degree of interchain entanglement, repairs the molecular chain breakage defects generated during high-temperature grafting, and improves the melt strength and molecular structure stability of the system. The melting reaction conditions of 170~230℃ are conducive to promoting the full ring-opening of epoxy groups and improving the chain extension reaction efficiency. The appropriate stirring speed can improve the dispersion uniformity of epoxy chain extenders in the melt, so that the resulting pre-modified melt has better flow stability, interfacial reactivity and particle coating ability, thus providing a good toughness foundation and interfacial support for the subsequent high-filling coal-based solid waste system.

[0031] S2.3 Continue to heat and stir the pre-modified melt for 3~10 min, and then perform devolatilization treatment for 1~5 min under a vacuum of -0.06~-0.095MPa to obtain the modified melt.

[0032] Continuing to heat and stir the pre-modified melt is beneficial for the epoxy chain extender to react more fully with the active groups on the polyolefin chain, thereby improving the degree of chain extension reaction and the uniformity of molecular structure. Subsequently, vacuum devolatilization treatment can effectively remove unreacted small molecule anhydrides, oligomers and volatile byproducts generated during the reaction, reduce the impact of residual volatiles on subsequent composite processing and interface stability, and avoid the generation of bubbles, pores and local defects during high-temperature processing.

[0033] S3. Add the modified particles to the modified melt and stir to obtain a mixed slurry. Then add amine crosslinking agent and epoxy borate ester, heat and stir to react, extrude, cool and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch.

[0034] In step S3, the amine crosslinking agent includes at least one of ethylenediamine, diethylenetriamine, isophorone diamine, and polyetheramine; the epoxy borate ester is obtained by reacting boric acid compounds with epoxy compounds; and the functional additives include at least one of plasticizers, antioxidants, lubricants, and light stabilizers.

[0035] After the modified particles are uniformly dispersed in the modified melt, the hydroxyl and borate ester structures on the particle surface react with the borate ester ends and epoxy groups in the epoxy borate ester, fixing the epoxy borate ester to the particle surface. Subsequently, the amine groups in the amine crosslinking agent undergo ring-opening reactions with the unreacted epoxy groups of the epoxy borate ester and the hydroxyl groups on the particle surface to form β-hydroxyamine bonds, which further react with the anhydride groups or hydroxyl groups on the polyolefin chains in the modified melt to form amide bonds or hydroxyamine bonds, thereby constructing a continuous multivalent covalent interface network. This ordered interfacial covalent connection structure can significantly improve the interfacial bonding strength and stress transfer efficiency between particles and the matrix, effectively alleviating the problems of interfacial stress concentration and crack propagation in highly filled coal-based solid waste systems, thereby significantly improving the toughness, impact resistance, processing stability, and overall mechanical properties of coal-based solid waste stone-plastic composite masterbatch.

[0036] Step S3 includes: S3.1 Add the modified particles to the modified melt, and stir and react at 170~220℃ for 20~30min to obtain a mixed slurry. The amount of modified particles added is 40~60wt% of the total mass of the modified melt, and the stirring speed is 100~500r / min.

[0037] In the modified melt, the anhydride groups preferentially undergo interfacial esterification with the hydroxyl groups on the surface of the modified particles, initially anchoring the polyolefin segments covalently to the particle surface. This forms a stable pre-interfacial layer between the particles and the polyolefin matrix. This pre-interfacial layer not only improves the wettability and dispersion stability of the particles in the molten system but also facilitates the enrichment of subsequently added epoxy borate esters in the particle interface region and provides directional reaction sites for further reactions between the amine crosslinking agent and the interfacial active groups. Since the hydroxyl-anhydride reaction mainly occurs in the local contact area on the particle surface, some unreacted anhydride groups, hydroxyl groups, and other active sites remain in the system, which can continue to participate in subsequent interfacial crosslinking reactions. This allows the subsequently formed continuous covalent network to be oriented along the pre-anchored interface, further improving the interfacial bonding strength and stress transfer efficiency between the particles and the polyolefin matrix.

[0038] S3.2 Add the amine crosslinking agent and epoxy borate ester to the mixed slurry, and continue to melt and stir for 10-15 minutes to obtain the crosslinking liquid. The amount of amine crosslinking agent and epoxy borate ester added is 1-2 wt% and 2-6 wt% of the total mass of the modified melt, respectively.

[0039] After adding an amine crosslinking agent and epoxy borate ester to the mixed slurry, the epoxy borate ester preferentially accumulates and is fixed in the particle interface region pre-anchored by acid anhydride groups. The borate ester structure forms stable BOC linkages with the hydroxyl groups on the particle surface, while its epoxy groups further participate in subsequent crosslinking reactions as interfacial active sites. Subsequently, the amine groups in the amine crosslinking agent undergo a ring-opening reaction with the epoxy groups in the epoxy borate ester to form a β-hydroxyamine structure. Simultaneously, the remaining amine groups continue to react with unreacted acid anhydride groups in the modified melt, and with the carboxyl groups remaining from the ring-opening reaction between the hydroxyl groups and acid anhydride groups on the particle surface. This gradually constructs a continuous, multivalent covalently bridging network along the pre-anchored particle interface. This continuous interfacial crosslinking structure significantly improves the interfacial bonding strength and stress transfer efficiency between particles and the polyolefin matrix, reduces the tendency for interfacial debonding and crack propagation in highly filled coal-based solid waste systems, and effectively enhances the interfacial stability, melt processing stability, and the toughness and impact resistance of the final composite masterbatch.

[0040] It should be noted that epoxy borate esters are obtained by reacting boric acid compounds with epoxy compounds, and the boric acid compounds include at least one of boric acid, phenylboronic acid, and 4-carboxyphenylboronic acid, and the epoxy compounds include at least one of bisphenol A diglycidyl ether, 1,6-hexanediol diglycidyl ether, and polyethylene glycol diglycidyl ether. Therefore, when the boric acid compound is boric acid, the epoxy borate esters formed by it and the epoxy compound are bisphenol A diglycidyl ether borate, 1,6-hexanediol diglycidyl ether borate, and polyethylene glycol diglycidyl ether borate, respectively.

[0041] Similarly, when the boric acid compound is phenylboronic acid, the epoxy borate esters formed by it and the epoxy compound are bisphenol A diglycidyl ether phenylboronic acid ester, 1,6-hexanediol diglycidyl ether phenylboronic acid ester, and polyethylene glycol diglycidyl ether phenylboronic acid ester, respectively. When the boric acid compound is 4-carboxyphenylboronic acid, the epoxy borate esters formed by it and the epoxy compound are bisphenol A diglycidyl ether-4-carboxyphenylboronic acid ester, 1,6-hexanediol diglycidyl ether-4-carboxyphenylboronic acid ester, and polyethylene glycol diglycidyl ether-4-carboxyphenylboronic acid ester, respectively.

[0042] In one embodiment, the preparation process of epoxy borate ester is as follows: Boric acid compounds, epoxy compounds, and catalysts are added to a reaction vessel, heated to 70-120°C, and stirred for 1-4 hours. The mixture is then volatilized at -0.03 to -0.08 MPa for 5-30 minutes to obtain epoxy borate esters. The molar ratio of epoxy groups to boric acid hydroxyl groups is (2-4):1. The catalyst includes at least one of triethylamine, N,N-dimethylbenzylamine, 2-methylimidazole, and 2-ethyl-4-methylimidazole. The amount of catalyst added is 0.1-2 wt% of the total mass of the boric acid compounds and epoxy compounds.

[0043] In borate compounds, the borate hydroxyl group (B-OH) first undergoes a ring-opening esterification reaction with the epoxy group in the epoxy compound under the action of a catalyst. The epoxy group is activated under heating conditions, and its three-membered ring structure opens to form a β-hydroxy ether structure. The borate hydroxyl group then forms a BOC bond with the hydroxyl carbon after ring opening, thereby generating an epoxy borate ester containing a borate ester structure. Since the molar ratio of epoxy group to borate hydroxyl group is controlled at (2~4):1, after some epoxy groups participate in the borate esterification reaction, unreacted epoxy groups are still retained in the system. Therefore, the obtained product contains both the borate ester structure and the active epoxy groups that can participate in subsequent interfacial crosslinking. Furthermore, continuous stirring at 70~120℃ for 1~4h can improve the contact efficiency and reaction conversion rate between the borate hydroxyl group and the epoxy group. Subsequently, devolatilization treatment at -0.03~-0.08MPa can remove unreacted small molecules, byproducts, and volatile components, shifting the borate esterification equilibrium towards the product direction, thereby obtaining an epoxy borate ester with a stable structure and sufficient retention of active epoxy groups.

[0044] S3.3 Add functional additives to the crosslinking liquid, continue to melt and mix for 3~10 min, extrude at 170~200℃, cool, and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch, wherein the amount of functional additives added is 1~10 wt% of the total mass of the modified melt.

[0045] Adding functional additives to the crosslinking liquid and continuing to melt and mix allows functional components such as plasticizers, antioxidants, lubricants, and light stabilizers to be uniformly dispersed in the composite system that has formed a continuous covalent interfacial network. Among them, plasticizers can improve the flexibility of polyolefin segments and alleviate interfacial stress concentration in high-filled coal-based solid waste systems; antioxidants can inhibit the thermo-oxidative degradation of polyolefin chains during high-temperature melting and extrusion, and maintain the stability of the interfacial crosslinking structure; lubricants can reduce the viscosity of the melt system and improve the flowability and extrusion processing stability of the high-filled system; and light stabilizers can improve the aging resistance of the composite masterbatch during subsequent use.

[0046] The plasticizer includes at least one of dioctyl phthalate, epoxidized soybean oil, dibutyl phthalate, dioctyl adipate, and tributyl citrate; the antioxidant includes at least one of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 1098, and antioxidant 626; the lubricant includes at least one of zinc stearate, calcium stearate, paraffin wax, polyethylene wax, and stearic acid; and the light stabilizer includes at least one of ultraviolet absorber UV-531, ultraviolet absorber UV-326, ultraviolet absorber UV-327, hindered amine light stabilizer 770, hindered amine light stabilizer 944, and hindered amine light stabilizer 622.

[0047] In addition, a coal-based solid waste stone-plastic composite masterbatch is proposed, which is prepared by the preparation method of the coal-based solid waste stone-plastic composite masterbatch described above.

[0048] For example, the present invention provides the following specific embodiments to illustrate the specific preparation method: Example 1: S1.1 After crushing the coal gangue, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 600℃ for 2 hours to obtain activated particles, wherein the particle size of the coal-based particles is 50μm. S1.2 Add boric acid and sodium lignosulfonate to deionized water and stir at 60°C for 30 min to obtain a modified solution, wherein the concentrations of boric acid and sodium lignosulfonate in the modified solution are 3 wt% and 5 wt%, respectively. S1.3 Add the activated particles to the modification solution, stir and react at 80℃ for 2 hours, filter and dry to obtain the modified particles, wherein the mass ratio of activated particles to modification solution is 1:3, and the stirring speed is 500 r / min; S2.1 Add polypropylene, maleic anhydride and dicumyl peroxide to a reaction vessel, heat to 180°C in an inert atmosphere and stir for 40 min to obtain anhydride-modified polyolefin, wherein the mass ratio of polypropylene:maleic anhydride:dicumyl peroxide is 100:6:0.5 and the stirring speed is 800 r / min. S2.2 Add glycidyl methacrylate to the anhydride-modified polyolefin, heat to 200℃ and stir for 15 min to obtain a pre-modified melt. The amount of glycidyl methacrylate added is 3 wt% of the total amount of polypropylene, and the stirring speed is 400 r / min. S2.3. Continue to heat and stir the pre-modified melt for 6 minutes, and then perform devolatilization treatment under a vacuum of -0.08MPa for 3 minutes to obtain the modified melt. S3.1 Add the modified particles to the modified melt, melt and stir at 200℃ for 25 min to obtain a mixed slurry, wherein the amount of modified particles added is 50 wt% of the total mass of the modified melt, and the stirring speed is 300 r / min; S3.2 Add diethylenetriamine and bisphenol A diglycidyl ether borate to the mixed slurry, and continue to melt and stir for 10-15 minutes to obtain a crosslinked liquid. The amount of diethylenetriamine and bisphenol A diglycidyl ether borate added is 1.5 wt% and 4 wt% of the total mass of the modified melt, respectively. S3.3 Add functional additives to the crosslinking liquid, continue to melt and mix for 6 minutes, extrude at 185℃, cool, and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch. The amount of functional additives added is 5 wt% of the total mass of the modified melt, and the functional preparation is composed of dioctyl phthalate, antioxidant 1010 and zinc stearate mixed in a mass ratio of 50:40:10.

[0049] The preparation method of bisphenol A diglycidyl ether borate is as follows: Boric acid, bisphenol A diglycidyl ether, and triethylamine were added to a reaction vessel, heated to 100°C and stirred for 2.5 h. The mixture was then volatilized at -0.05 MPa for 20 min to obtain bisphenol A diglycidyl ether borate ester. The molar ratio of the epoxy group of bisphenol A diglycidyl ether to the boric acid hydroxyl group of boric acid was 3:1, and the amount of triethylamine added was 1 wt% of the total mass of boric acid and bisphenol A diglycidyl ether.

[0050] Example 2: S1.1 After crushing the coal gangue, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 600℃ for 2 hours to obtain activated particles, wherein the particle size of the coal-based particles is 50μm. S1.2 Add boric acid and sodium lignosulfonate to deionized water and stir at 60°C for 30 min to obtain a modified solution, wherein the concentrations of boric acid and sodium lignosulfonate in the modified solution are 3 wt% and 5 wt%, respectively. S1.3 Add the activated particles to the modified solution and stir at 80°C for 2 hours to obtain a modified dispersion. The mass ratio of activated particles to modified solution is 1:3, and the stirring speed is 500 r / min. S1.4. After the modified dispersion is cooled to 60℃, 1-ethyl-3-methylimidazolium tetrafluoroborate is added, and the reaction is continued with stirring for 1 hour. After filtration and drying, modified particles are obtained. The amount of 1-ethyl-3-methylimidazolium tetrafluoroborate added is 6 wt% of the total mass of coal gangue. S2.1 Add polypropylene, maleic anhydride and dicumyl peroxide to a reaction vessel, heat to 180°C in an inert atmosphere and stir for 40 min to obtain anhydride-modified polyolefin, wherein the mass ratio of polypropylene:maleic anhydride:dicumyl peroxide is 100:6:0.5 and the stirring speed is 800 r / min. S2.2 Add glycidyl methacrylate to the anhydride-modified polyolefin, heat to 200℃ and stir for 15 min to obtain a pre-modified melt. The amount of glycidyl methacrylate added is 3 wt% of the total amount of polypropylene, and the stirring speed is 400 r / min. S2.3. Continue to heat and stir the pre-modified melt for 6 minutes, and then perform devolatilization treatment under a vacuum of -0.08MPa for 3 minutes to obtain the modified melt. S3.1 Add the modified particles to the modified melt, melt and stir at 200℃ for 25 min to obtain a mixed slurry, wherein the amount of modified particles added is 50 wt% of the total mass of the modified melt, and the stirring speed is 300 r / min; S3.2 Add diethylenetriamine and bisphenol A diglycidyl ether borate to the mixed slurry, and continue to melt and stir for 10-15 minutes to obtain a crosslinked liquid. The amount of diethylenetriamine and bisphenol A diglycidyl ether borate added is 1.5 wt% and 4 wt% of the total mass of the modified melt, respectively. S3.3 Add functional additives to the crosslinking liquid, continue to melt and mix for 6 minutes, extrude at 185℃, cool, and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch. The amount of functional additives added is 5 wt% of the total mass of the modified melt, and the functional preparation is composed of dioctyl phthalate, antioxidant 1010 and zinc stearate mixed in a mass ratio of 50:40:10.

[0051] The preparation method of bisphenol A diglycidyl ether borate is as follows: Boric acid, bisphenol A diglycidyl ether, and triethylamine were added to a reaction vessel, heated to 100°C and stirred for 2.5 h. The mixture was then volatilized at -0.05 MPa for 20 min to obtain bisphenol A diglycidyl ether borate ester. The molar ratio of the epoxy group of bisphenol A diglycidyl ether to the boric acid hydroxyl group of boric acid was 3:1, and the amount of triethylamine added was 1 wt% of the total mass of boric acid and bisphenol A diglycidyl ether.

[0052] The process is basically the same as in Example 1, except that the modified particles obtained in step S1 are further treated with an imidazole compound.

[0053] Comparative Example 1: S1.1 After crushing the coal gangue, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 600℃ for 2 hours to obtain activated particles, wherein the particle size of the coal-based particles is 50μm. S1.2 Add sodium lignosulfonate to deionized water and stir at 60°C for 30 min to obtain a modified solution, wherein the concentration of sodium lignosulfonate in the modified solution is 5 wt%. S1.3 Add the activated particles to the modification solution, stir and react at 80℃ for 2 hours, filter and dry to obtain the modified particles, wherein the mass ratio of activated particles to modification solution is 1:3, and the stirring speed is 500 r / min; S2.1 Add polypropylene, maleic anhydride and dicumyl peroxide to a reaction vessel, heat to 180°C in an inert atmosphere and stir for 40 min to obtain anhydride-modified polyolefin, wherein the mass ratio of polypropylene:maleic anhydride:dicumyl peroxide is 100:6:0.5 and the stirring speed is 800 r / min. S2.2 Add glycidyl methacrylate to the anhydride-modified polyolefin, heat to 200℃ and stir for 15 min to obtain a pre-modified melt. The amount of glycidyl methacrylate added is 3 wt% of the total amount of polypropylene, and the stirring speed is 400 r / min. S2.3. Continue to heat and stir the pre-modified melt for 6 minutes, and then perform devolatilization treatment under a vacuum of -0.08MPa for 3 minutes to obtain the modified melt. S3.1 Add the modified particles to the modified melt, melt and stir at 200℃ for 25 min to obtain a mixed slurry, wherein the amount of modified particles added is 50 wt% of the total mass of the modified melt, and the stirring speed is 300 r / min; S3.2 Add diethylenetriamine and bisphenol A diglycidyl ether borate to the mixed slurry, and continue to melt and stir for 10-15 minutes to obtain a crosslinked liquid. The amount of diethylenetriamine and bisphenol A diglycidyl ether borate added is 1.5 wt% and 4 wt% of the total mass of the modified melt, respectively. S3.3 Add functional additives to the crosslinking liquid, continue to melt and mix for 6 minutes, extrude at 185℃, cool, and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch. The amount of functional additives added is 5 wt% of the total mass of the modified melt, and the functional preparation is composed of dioctyl phthalate, antioxidant 1010 and zinc stearate mixed in a mass ratio of 50:40:10.

[0054] The preparation method of bisphenol A diglycidyl ether borate is as shown in Example 1, and will not be described in detail here.

[0055] It is basically the same as Example 1, except that boric acid is not added in step S1.2, that is, boric acid compound is not used in step S1.

[0056] Comparative Example 2: S1.1 After crushing the coal gangue, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 600℃ for 2 hours to obtain activated particles, wherein the particle size of the coal-based particles is 50μm. S1.2 Add boric acid to deionized water and stir at 60°C for 30 minutes to obtain a modified solution, wherein the concentration of boric acid in the modified solution is 3 wt%. S1.3 Add the activated particles to the modification solution, stir and react at 80℃ for 2 hours, filter and dry to obtain the modified particles, wherein the mass ratio of activated particles to modification solution is 1:3, and the stirring speed is 500 r / min; S2.1 Add polypropylene, maleic anhydride and dicumyl peroxide to a reaction vessel, heat to 180°C in an inert atmosphere and stir for 40 min to obtain anhydride-modified polyolefin, wherein the mass ratio of polypropylene:maleic anhydride:dicumyl peroxide is 100:6:0.5 and the stirring speed is 800 r / min. S2.2 Add glycidyl methacrylate to the anhydride-modified polyolefin, heat to 200℃ and stir for 15 min to obtain a pre-modified melt. The amount of glycidyl methacrylate added is 3 wt% of the total amount of polypropylene, and the stirring speed is 400 r / min. S2.3. Continue to heat and stir the pre-modified melt for 6 minutes, and then perform devolatilization treatment under a vacuum of -0.08MPa for 3 minutes to obtain the modified melt. S3.1 Add the modified particles to the modified melt, melt and stir at 200℃ for 25 min to obtain a mixed slurry, wherein the amount of modified particles added is 50 wt% of the total mass of the modified melt, and the stirring speed is 300 r / min; S3.2 Add diethylenetriamine and bisphenol A diglycidyl ether borate to the mixed slurry, and continue to melt and stir for 10-15 minutes to obtain a crosslinked liquid. The amount of diethylenetriamine and bisphenol A diglycidyl ether borate added is 1.5 wt% and 4 wt% of the total mass of the modified melt, respectively. S3.3 Add functional additives to the crosslinking liquid, continue to melt and mix for 6 minutes, extrude at 185℃, cool, and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch. The amount of functional additives added is 5 wt% of the total mass of the modified melt, and the functional preparation is composed of dioctyl phthalate, antioxidant 1010 and zinc stearate mixed in a mass ratio of 50:40:10.

[0057] The preparation method of bisphenol A diglycidyl ether borate is as shown in Example 1, and will not be described in detail here.

[0058] It is basically the same as Example 1, except that sodium lignosulfonate is not added in step S1.2, that is, lignosulfonate is not used in step S1.

[0059] Comparative Example 3: S1.1 After crushing the coal gangue, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 600℃ for 2 hours to obtain activated particles, wherein the particle size of the coal-based particles is 50μm. S1.2 Add boric acid and sodium lignosulfonate to deionized water and stir at 60°C for 30 min to obtain a modified solution, wherein the concentrations of boric acid and sodium lignosulfonate in the modified solution are 3 wt% and 5 wt%, respectively. S1.3 Add the activated particles to the modification solution, stir and react at 80℃ for 2 hours, filter and dry to obtain the modified particles, wherein the mass ratio of activated particles to modification solution is 1:3, and the stirring speed is 500 r / min; S2.1 Add polypropylene to the reactor, heat to 180°C in an inert atmosphere, stir and react for 40 minutes to obtain polypropylene melt, wherein the stirring speed is 800 r / min; S2.2 Add glycidyl methacrylate to the polypropylene melt, heat to 200℃ and stir for 15 min to obtain the pre-modified melt. The amount of glycidyl methacrylate added is 3 wt% of the total amount of polypropylene, and the stirring speed is 400 r / min. S2.3. Continue to heat and stir the pre-modified melt for 6 minutes, and then perform devolatilization treatment under a vacuum of -0.08MPa for 3 minutes to obtain the modified melt. S3.1 Add the modified particles to the modified melt, melt and stir at 200℃ for 25 min to obtain a mixed slurry, wherein the amount of modified particles added is 50 wt% of the total mass of the modified melt, and the stirring speed is 300 r / min; S3.2 Add diethylenetriamine and bisphenol A diglycidyl ether borate to the mixed slurry, and continue to melt and stir for 10-15 minutes to obtain a crosslinked liquid. The amount of diethylenetriamine and bisphenol A diglycidyl ether borate added is 1.5 wt% and 4 wt% of the total mass of the modified melt, respectively. S3.3 Add functional additives to the crosslinking liquid, continue to melt and mix for 6 minutes, extrude at 185℃, cool, and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch. The amount of functional additives added is 5 wt% of the total mass of the modified melt, and the functional preparation is composed of dioctyl phthalate, antioxidant 1010 and zinc stearate mixed in a mass ratio of 50:40:10.

[0060] The preparation method of bisphenol A diglycidyl ether borate is as shown in Example 1, and will not be described in detail here.

[0061] It is basically the same as Example 1, except that maleic anhydride is not used in step S2.1, that is, no acid anhydride compound is used in step S2.

[0062] Comparative Example 4: S1.1 After crushing the coal gangue, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 600℃ for 2 hours to obtain activated particles, wherein the particle size of the coal-based particles is 50μm. S1.2 Add boric acid and sodium lignosulfonate to deionized water and stir at 60°C for 30 min to obtain a modified solution, wherein the concentrations of boric acid and sodium lignosulfonate in the modified solution are 3 wt% and 5 wt%, respectively. S1.3 Add the activated particles to the modification solution, stir and react at 80℃ for 2 hours, filter and dry to obtain the modified particles, wherein the mass ratio of activated particles to modification solution is 1:3, and the stirring speed is 500 r / min; S2.1 Add polypropylene, maleic anhydride and dicumyl peroxide to a reaction vessel, heat to 180°C in an inert atmosphere and stir for 40 min to obtain anhydride-modified polyolefin, wherein the mass ratio of polypropylene:maleic anhydride:dicumyl peroxide is 100:6:0.5 and the stirring speed is 800 r / min. S2.2. The anhydride-modified polyolefin is heated to 200℃ and stirred for 15 min to obtain a pre-modified melt, wherein the stirring speed is 400 r / min; S2.3. Continue to heat and stir the pre-modified melt for 6 minutes, and then perform devolatilization treatment under a vacuum of -0.08MPa for 3 minutes to obtain the modified melt. S3.1 Add the modified particles to the modified melt, melt and stir at 200℃ for 25 min to obtain a mixed slurry, wherein the amount of modified particles added is 50 wt% of the total mass of the modified melt, and the stirring speed is 300 r / min; S3.2 Add diethylenetriamine and bisphenol A diglycidyl ether borate to the mixed slurry, and continue to melt and stir for 10-15 minutes to obtain a crosslinked liquid. The amount of diethylenetriamine and bisphenol A diglycidyl ether borate added is 1.5 wt% and 4 wt% of the total mass of the modified melt, respectively. S3.3 Add functional additives to the crosslinking liquid, continue to melt and mix for 6 minutes, extrude at 185℃, cool, and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch. The amount of functional additives added is 5 wt% of the total mass of the modified melt, and the functional preparation is composed of dioctyl phthalate, antioxidant 1010 and zinc stearate mixed in a mass ratio of 50:40:10.

[0063] The preparation method of bisphenol A diglycidyl ether borate is as shown in Example 1, and will not be described in detail here.

[0064] It is basically the same as Example 1, except that glycidyl methacrylate is not used in step S2.2, that is, epoxy chain extender is not used in step S2.

[0065] Comparative Example 5: S1.1 After crushing the coal gangue, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 600℃ for 2 hours to obtain activated particles, wherein the particle size of the coal-based particles is 50μm. S1.2 Add boric acid and sodium lignosulfonate to deionized water and stir at 60°C for 30 min to obtain a modified solution, wherein the concentrations of boric acid and sodium lignosulfonate in the modified solution are 3 wt% and 5 wt%, respectively. S1.3 Add the activated particles to the modification solution, stir and react at 80℃ for 2 hours, filter and dry to obtain the modified particles, wherein the mass ratio of activated particles to modification solution is 1:3, and the stirring speed is 500 r / min; S2.1 Add polypropylene, maleic anhydride and dicumyl peroxide to a reaction vessel, heat to 180°C in an inert atmosphere and stir for 40 min to obtain anhydride-modified polyolefin, wherein the mass ratio of polypropylene:maleic anhydride:dicumyl peroxide is 100:6:0.5 and the stirring speed is 800 r / min. S2.2 Add glycidyl methacrylate to the anhydride-modified polyolefin, heat to 200℃ and stir for 15 min to obtain a pre-modified melt. The amount of glycidyl methacrylate added is 3 wt% of the total amount of polypropylene, and the stirring speed is 400 r / min. S2.3. Continue to heat and stir the pre-modified melt for 6 minutes, and then perform devolatilization treatment under a vacuum of -0.08MPa for 3 minutes to obtain the modified melt. S3.1 Add the modified particles to the modified melt, melt and stir at 200℃ for 25 min to obtain a mixed slurry, wherein the amount of modified particles added is 50 wt% of the total mass of the modified melt, and the stirring speed is 300 r / min; S3.2 Add bisphenol A diglycidyl ether borate to the mixed slurry and continue to melt and stir for 10-15 minutes to obtain a crosslinked liquid. The amount of bisphenol A diglycidyl ether borate added is 4 wt% of the total mass of the modified melt. S3.3 Add functional additives to the crosslinking liquid, continue to melt and mix for 6 minutes, extrude at 185℃, cool, and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch. The amount of functional additives added is 5 wt% of the total mass of the modified melt, and the functional preparation is composed of dioctyl phthalate, antioxidant 1010 and zinc stearate mixed in a mass ratio of 50:40:10.

[0066] The preparation method of bisphenol A diglycidyl ether borate is as shown in Example 1, and will not be described in detail here.

[0067] It is basically the same as Example 1, except that diethylenetriamine is not used in step S3.2, that is, no amine crosslinking agent is used in step S3.

[0068] Comparative Example 6: S1.1 After crushing the coal gangue, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 600℃ for 2 hours to obtain activated particles, wherein the particle size of the coal-based particles is 50μm. S1.2 Add boric acid and sodium lignosulfonate to deionized water and stir at 60°C for 30 min to obtain a modified solution, wherein the concentrations of boric acid and sodium lignosulfonate in the modified solution are 3 wt% and 5 wt%, respectively. S1.3 Add the activated particles to the modification solution, stir and react at 80℃ for 2 hours, filter and dry to obtain the modified particles, wherein the mass ratio of activated particles to modification solution is 1:3, and the stirring speed is 500 r / min; S2.1 Add polypropylene, maleic anhydride and dicumyl peroxide to a reaction vessel, heat to 180°C in an inert atmosphere and stir for 40 min to obtain anhydride-modified polyolefin, wherein the mass ratio of polypropylene:maleic anhydride:dicumyl peroxide is 100:6:0.5 and the stirring speed is 800 r / min. S2.2 Add glycidyl methacrylate to the anhydride-modified polyolefin, heat to 200℃ and stir for 15 min to obtain a pre-modified melt. The amount of glycidyl methacrylate added is 3 wt% of the total amount of polypropylene, and the stirring speed is 400 r / min. S2.3. Continue to heat and stir the pre-modified melt for 6 minutes, and then perform devolatilization treatment under a vacuum of -0.08MPa for 3 minutes to obtain the modified melt. S3.1 Add the modified particles to the modified melt, melt and stir at 200℃ for 25 min to obtain a mixed slurry, wherein the amount of modified particles added is 50 wt% of the total mass of the modified melt, and the stirring speed is 300 r / min; S3.2 Add diethylenetriamine to the mixed slurry and continue to melt and stir for 10-15 minutes to obtain a crosslinked liquid, wherein the amount of diethylenetriamine added is 1.5 wt% of the total mass of the modified melt. S3.3 Add functional additives to the crosslinking liquid, continue to melt and mix for 6 minutes, extrude at 185℃, cool, and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch. The amount of functional additives added is 5 wt% of the total mass of the modified melt, and the functional preparation is composed of dioctyl phthalate, antioxidant 1010 and zinc stearate mixed in a mass ratio of 50:40:10.

[0069] It is basically the same as Example 1, except that bisphenol A diglycidyl ether borate is not used in step S3.2, that is, epoxy borate is not used in step S3.

[0070] Comparative Example 7: After crushing the coal gangue, it was added to a ball mill for grinding to obtain coal-based particles with a particle size of 50μm. The coal-based particles were then calcined at 600℃ for 2 hours to obtain activated particles. Polypropylene was then heated to 180℃ in an inert atmosphere and stirred for 40 minutes to obtain molten polyolefin. Coal gangue was then added and stirred at 200℃ for 25 minutes to obtain a mixed slurry. Finally, functional additives were added, and the mixture was stirred and mixed for another 6 minutes. The mixture was then extruded at 185℃, cooled, and pelletized to obtain coal-based solid waste stone-plastic composite masterbatch. The amount of functional additives added was 5wt% of the total mass of the molten polyolefin, and the functional preparation was composed of dioctyl phthalate, antioxidant 1010, and zinc stearate mixed in a mass ratio of 50:40:10.

[0071] Performance testing: 1. Mechanical property testing: Impact strength: Refer to GB / T 1043.1-2008 "Determination of impact properties of simply supported plastic beams - Part 1: Non-instrumental impact test", prepare type A notched specimens respectively. The specimen condition is conditioned in the standard environment (23±2℃, relative humidity 50±5%) for at least 24 hours as specified in GB / T 2918. At least 5 specimens are tested in each group and the average value is taken.

[0072] Tensile elongation at break: The test was conducted in accordance with GB / T 1040.2-2022 "Determination of tensile properties of plastics - Part 2: Test conditions for molded and extruded plastics". A type 1A dumbbell-shaped specimen (total length ≥ 150 mm, gauge length 50 mm) was used. The specimen condition was conditioned in accordance with GB / T 2918 at (23±2)℃ and (50±10)% relative humidity. The specimen was stretched at a speed of 50 mm / min using a universal testing machine until it broke. At least 5 specimens were tested in each group and the average value was taken.

[0073] The test results are shown in Table 1.

[0074] Table 1. Performance Tests of Coal-Based Solid Waste Petrochemical Composite Masterbatch: As shown in Table 1, compared with the coal-based solid waste stone-plastic composite masterbatch prepared by conventional melting in Comparative Example 7, the coal-based solid waste stone-plastic composite masterbatch prepared in Examples 1-2 exhibits higher impact strength and elongation at break. Among them, Example 2 further introduces imidazole ionic compounds based on Example 1, which can improve the dispersion uniformity of modified particles in the molten system, making stress transmission more uniform, and thus better toughness. Further observation of Examples 1 and Comparative Examples 1-6 shows that, compared with Example 1, Comparative Examples 1-6 lack at least one of boric acid compound, lignin sulfonate, acid anhydride compound, epoxy chain extender, amine crosslinking agent or epoxy borate ester, resulting in reduced interfacial bonding ability and stress transmission ability between coal-based solid waste particles and polypropylene matrix. Therefore, their impact strength and elongation at break are lower than those of Example 1.

[0075] 2. Stability Test: Melt Flow Index (MFR): The coal-based solid waste stone-plastic composite masterbatches prepared in Example 1 and Comparative Example 4 were tested according to GB / T3682.1-2018. The preferred test conditions were 230℃ and 2.16kg load. The appearance of the extruded strip was observed to see if there were any phenomena such as melt fracture or broken strips. The test results are shown in Table 2.

[0076] Table 2. Stability of Coal-based Solid Waste Petrochemical Composite Masterbatch: As shown in Table 2, in Comparative Example 4, due to the absence of epoxy chain extender, polypropylene was prone to molecular chain breakage during high-temperature grafting and melt shearing, resulting in a decrease in molecular weight and melt viscosity. Consequently, its melt index increased to 11.2 g / 10 min. However, due to insufficient melt strength, melt fracture and strip breakage were prone to occur during extrusion, resulting in poor processing stability. In contrast, in Example 1, after the addition of epoxy chain extender, the epoxy groups could undergo chain extension reactions with the hydroxyl chain ends generated by polypropylene degradation, thereby repairing the broken molecular chains and improving the degree of molecular chain entanglement. This reduced the melt index of the system to 8.8 g / 10 min, while significantly improving melt continuity. The extrusion process was stable and there were no obvious strip breakage phenomena.

[0077] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

[0078] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A method for preparing coal-based solid waste stone-plastic composite masterbatch, characterized in that, The preparation method includes the following preparation steps: S1. After crushing, calcining and activating the coal-based solid waste, it is added to a modified solution containing boric acid compounds and lignin sulfonate, and heated and stirred to react, thereby obtaining modified particles. S2. Mix polyolefin and acid anhydride compound, heat and react to obtain acid anhydride modified polyolefin, then add epoxy chain extender, continue heating and react to obtain modified melt, wherein the acid anhydride compound contains carbon-carbon double bonds; S3. Add the modified particles to the modified melt and stir to obtain a mixed slurry. Then add amine crosslinking agent and epoxy borate ester, heat and stir to react, extrude, cool and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch.

2. The method for preparing a coal-based solid waste stone-plastic composite masterbatch according to claim 1, characterized in that, Step S1 includes: S1.1 After crushing the coal-based solid waste, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 450~700℃ for 1~3h to obtain activated particles, wherein the particle size of the coal-based particles is 10~80μm. S1.2 Add boric acid compound and lignosulfonate to deionized water, stir at 50~70℃ for 20~40 min to obtain modified solution, wherein the concentrations of boric acid compound and lignosulfonate in the modified solution are 1~5wt% and 2~8wt%, respectively; S1.3 Add the activated particles to the modification solution, stir and react at 70~95℃ for 1~3h, filter and dry to obtain modified particles, wherein the mass ratio of activated particles to modification solution is 1:(1.5~4), and the stirring speed is 300~800r / min.

3. The method for preparing a coal-based solid waste stone-plastic composite masterbatch according to claim 2, characterized in that, In step S1, the coal-based solid waste includes at least one of coal gangue, fly ash, and gasification slag; the boric acid compound includes at least one of boric acid, borax, sodium metaborate, sodium perborate, or ammonium metaborate; and the lignin sulfonate includes at least one of sodium lignin sulfonate, calcium lignin sulfonate, magnesium lignin sulfonate, ammonium lignin sulfonate, and potassium lignin sulfonate.

4. The method for preparing a coal-based solid waste stone-plastic composite masterbatch according to claim 2, characterized in that, Step S1 also includes: S1.1 After crushing the coal-based solid waste, it is added to a ball mill for grinding to obtain coal-based particles. The coal-based particles are then calcined at 450~700℃ for 1~3h to obtain activated particles, wherein the particle size of the coal-based particles is 10~80μm. S1.2 Add boric acid compound and lignosulfonate to deionized water, stir at 50~70℃ for 20~40 min to obtain modified solution, wherein the concentrations of boric acid compound and lignosulfonate in the modified solution are 1~5wt% and 2~8wt%, respectively; S1.3 Add the activated particles to the modified solution and stir at 70~95℃ for 1~3h to obtain a modified dispersion. The mass ratio of activated particles to modified solution is 1:(1.5~4), and the stirring speed is 300~800r / min. S1.

4. After the modified dispersion is cooled to 50~75℃, add the imidazole compound, continue stirring and reacting for 0.5~2h, filter and dry to obtain modified particles. The amount of imidazole compound added is 4~8wt% of the total mass of coal-based solid waste. The imidazole compound includes at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-hexyl-3-methylimidazolium bromide.

5. The method for preparing a coal-based solid waste stone-plastic composite masterbatch according to claim 1, characterized in that, Step S2 includes: S2.1 Add polyolefin, acid anhydride compound and free radical initiator to a reaction vessel, heat to 160~210℃ in an inert atmosphere and stir for 30~50 min to obtain acid anhydride modified polyolefin, wherein the mass ratio of polyolefin: acid anhydride compound: free radical initiator is 100:(4~8):(0.05~1), and the stirring speed is 300~1200 r / min; S2.2 Add epoxy chain extender to anhydride-modified polyolefin, heat to 170~230℃ and stir for 10~20 min to obtain pre-modified melt, wherein the amount of epoxy chain extender added is 1~5wt% of the total amount of polyolefin, and the stirring speed is 200~600r / min; S2.3 Continue to heat and stir the pre-modified melt for 3~10 min, and then perform devolatilization treatment for 1~5 min under a vacuum of -0.06~-0.095MPa to obtain the modified melt.

6. The method for preparing a coal-based solid waste stone-plastic composite masterbatch according to claim 5, characterized in that, In step S2, the polyolefin includes at least one of polyethylene, polypropylene, and high-density polyethylene; the acid anhydride compound includes at least one of maleic anhydride, itaconic anhydride, and methyltetrahydrophthalic anhydride; the free radical initiator includes at least one of dicumyl peroxide, benzoyl peroxide, and di-tert-butyl peroxide; and the epoxy chain extender includes at least one of glycidyl methacrylate, bisphenol A diglycidyl ether, polyethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and pentaerythritol glycidyl ether.

7. The method for preparing a coal-based solid waste stone-plastic composite masterbatch according to claim 1, characterized in that, Step S3 includes: S3.1 Add the modified particles to the modified melt, and stir and react at 170~220℃ for 20~30min to obtain a mixed slurry. The amount of modified particles added is 40~60wt% of the total mass of the modified melt, and the stirring speed is 100~500r / min. S3.2 Add the amine crosslinking agent and epoxy borate ester to the mixed slurry, and continue to melt and stir for 10-15 minutes to obtain a crosslinked liquid. The amount of amine crosslinking agent and epoxy borate ester added is 1-2 wt% and 2-6 wt% of the total mass of the modified melt, respectively. S3.3 Add functional additives to the crosslinking liquid, continue to melt and mix for 3~10 min, extrude at 170~200℃, cool, and pelletize to obtain coal-based solid waste stone-plastic composite masterbatch, wherein the amount of functional additives added is 1~10 wt% of the total mass of the modified melt.

8. The method for preparing a coal-based solid waste stone-plastic composite masterbatch according to claim 7, characterized in that, In step S3, the amine crosslinking agent includes at least one of ethylenediamine, diethylenetriamine, isophorone diamine, and polyetheramine; the epoxy borate ester is obtained by reacting boric acid compounds with epoxy compounds; and the functional additives include at least one of plasticizers, antioxidants, lubricants, and light stabilizers.

9. The method for preparing a coal-based solid waste stone-plastic composite masterbatch according to claim 8, characterized in that, Boric acid compounds include at least one of boric acid, phenylboronic acid, and 4-carboxyphenylboronic acid; epoxy compounds include at least one of bisphenol A diglycidyl ether, 1,6-hexanediol diglycidyl ether, and polyethylene glycol diglycidyl ether. Plasticizers include at least one of dioctyl phthalate, epoxidized soybean oil, dibutyl phthalate, dioctyl adipate, and tributyl citrate; The antioxidants include at least one of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 1098, and antioxidant 626; Lubricants include at least one of zinc stearate, calcium stearate, paraffin wax, polyethylene wax, and stearic acid; The light stabilizer includes at least one of the following: UV absorber UV-531, UV absorber UV-326, UV absorber UV-327, hindered amine light stabilizer 770, hindered amine light stabilizer 944, and hindered amine light stabilizer 622.

10. A coal-based solid waste stone-plastic composite masterbatch, characterized in that, The coal-based solid waste stone-plastic composite masterbatch is prepared by any one of the preparation methods of coal-based solid waste stone-plastic composite masterbatch according to claims 1-9.

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