High-performance modified heavy calcium carbonate and application thereof in polymer composite material

Abstract

The invention discloses high-performance modified heavy calcium carbonate and application thereof in a polymer composite material, and relates to the technical field of composite materials. The polymer composite material is prepared from the following raw materials in parts by mass: 0.1 to 20 parts of high-performance modified heavy calcium carbonate, 0.1 to 5 parts of beta nucleating agent and 75 to 99.8 parts of polypropylene. The normal-temperature and low-temperature impact strength of the PP material can be improved by independently adding the modified heavy calcium carbonate or the beta nucleating agent, but the low-temperature toughness improvement effect is limited, and the tensile property of the material can be reduced to different degrees. The combination of the high-performance modified heavy calcium carbonate and the beta nucleating agent has a synergistic effect on the improvement of the tensile property and the normal-temperature and low-temperature impact properties of the PP material, so that the mechanical properties of the PP material are comprehensively improved.

Description

[Technical Field]

[0001] This invention belongs to the field of polymer composite material preparation technology, specifically relating to a high-performance modified heavy calcium carbonate and its application in polymer composite materials. [Background Technology]

[0002] Calcium carbonate, as an abundant inorganic filler, has been widely used in the fields of plastics, rubber, coatings, and other polymer materials due to its readily available raw materials, low production cost, and good reinforcing effect, playing an important role in reducing product costs and improving processing performance. However, untreated calcium carbonate particles have a large number of hydroxyl groups on their surface, exhibiting strong hydrophilicity. This results in a significant difference in interfacial energy between the filler and hydrophobic polymer matrices such as polyolefins, leading to poor compatibility and weak interfacial bonding. This directly causes uneven dispersion and easy aggregation of the filler in the matrix, which in turn leads to a decline in the mechanical properties of composite materials, especially in terms of reduced impact strength and deteriorated processing fluidity, severely limiting its application in high-performance polymer products.

[0003] Polypropylene (PP), as one of the world's most produced general-purpose thermoplastics, is widely used in automobile manufacturing, home appliances, and packaging materials due to its excellent mechanical strength, chemical stability, weather resistance, low cost, and ease of processing. However, the presence of numerous side methyl groups in the PP molecular chain results in high molecular chain rigidity and a tendency to form large spherulite structures during crystallization. This leads to insufficient impact toughness, especially at low temperatures where it is prone to brittle fracture. Consequently, it fails to meet the impact resistance requirements of high-end products, significantly limiting its application in fields with stringent toughness requirements, such as automotive bumpers and electronic device housings.

[0004] With the ever-increasing demands of modern industry on the performance of polymer materials, how to simultaneously improve the impact toughness of polypropylene and the dispersion compatibility of calcium carbonate fillers through simple and effective methods has become a pressing technical problem in this field. Currently, the industry has recognized that surface modification of calcium carbonate (such as using coupling agents and surfactants to change its surface from hydrophilic to oleophilic) can enhance its interfacial bonding with the polypropylene matrix; simultaneously, introducing β-nucleating agents can effectively refine the spherulitic structure of polypropylene and improve its impact performance. These technical approaches provide feasible solutions to the performance defects of polypropylene materials, but their synergistic mechanisms and industrial application effects still need further optimization. Therefore, developing efficient and low-cost composite modification technologies has significant practical importance and application value. [Summary of the Invention]

[0005] The purpose of this invention is to provide a high-performance modified heavy calcium carbonate and its application in polymer composites. This invention combines a β-nucleating agent with modified heavy calcium carbonate to optimize the performance of polypropylene (PP). The introduction of the β-nucleating agent effectively promotes the ordered arrangement of PP molecular chains, inducing the formation of β-crystals with higher toughness and better low-temperature performance, significantly accelerating the crystallization rate of PP, and thus enhancing the overall strength of the material. The introduction of modified heavy calcium carbonate allows PP to be both toughened and stiffened, significantly improving its low-temperature impact performance, crystallinity, and crystallization rate. Furthermore, the addition of modified heavy calcium carbonate brings cost benefits, helping to reduce material costs. In composite materials, the combination of modified heavy calcium carbonate and the β-nucleating agent not only has a synergistic effect on β-crystal formation but also significantly improves the impact strength of PP, especially under low-temperature conditions. Therefore, this invention develops a polymer composite material with excellent room-temperature and low-temperature impact performance and outstanding tensile strength, optimizing its mechanical properties while achieving effective cost control, providing a new approach for the development of high-performance, low-cost polymer composites.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0007] A method for preparing high-performance modified heavy calcium carbonate includes the following steps:

[0008] (1) Pretreatment of calcium carbonate

[0009] Heavy calcium carbonate was dried at a temperature of 103-121℃ and a vacuum degree of ≤-0.08MPa for 2-4 hours.

[0010] (2) High-speed hybridization modification

[0011] The dried calcium carbonate is put into a high-speed mixer, and 3.4-9.5% of the calcium carbonate mass of macromolecular auxiliary agent, 1.2-4.8% of the calcium carbonate mass of Span 80 and 0.1-1% of the calcium carbonate mass of sodium hexametaphosphate are added. The mixture is mixed for 13-32 minutes at a mixing temperature of 62-75℃ and a speed of 1200-1800 r / min.

[0012] (3) Coupling agent synergistic treatment

[0013] Add 0.6-2.8% (by weight of calcium carbonate) of silane coupling agent KH550 and 0.5-0.9% (by weight of calcium carbonate) of water, and mix for 6-10 minutes at a mixing temperature of 76-88℃ and a rotation speed of 800-1000 r / min to obtain the material.

[0014] (4) Secondary dispersion enhancement

[0015] The material is transferred to an air jet mill and ultra-finely pulverized under compressed air of 0.6-0.8MPa to further refine the particles and uniformly coat them with macromolecular additives. Process parameters: feed rate 5.3-9.9kg / h, classifier speed 3000-5000r / min, pulverization temperature ≤39℃.

[0016] (5) Drying and sieving

[0017] Finally, dry at 60-80℃ for 1-2 hours and pass through an 800-1200 mesh sieve to obtain high-performance modified heavy calcium carbonate.

[0018] Furthermore, a bag filter is installed at the outlet of the high-speed mixer described in step (2), with a dust collection rate of ≥99%.

[0019] Furthermore, a bag filter is installed at the outlet of the airflow pulverizer described in step (4).

[0020] The present invention also provides an application of high-performance modified heavy calcium carbonate in polymer composite materials, wherein the raw materials include, by weight, 0.1-20 parts of high-performance modified heavy calcium carbonate, 0.1-5 parts of β-nucleating agent, and 75-99.8 parts of polypropylene.

[0021] Furthermore, the β-nucleating agent includes one or a mixture of several of rare earth elements, amides, dicarboxylic acids, fused ring compounds, and polymers.

[0022] Furthermore, the application of high-performance modified heavy calcium carbonate in polymer composites includes the following steps:

[0023] 1) Weigh high-performance modified heavy calcium carbonate and polypropylene by weight, mix them, add them to a twin-screw extruder, and then granulate them to obtain high-performance modified heavy calcium carbonate / polypropylene composite masterbatch.

[0024] 2) Add β-nucleating agent to high-performance modified heavy calcium carbonate / polypropylene composite masterbatch, mix and melt blend in a Haake torque rheometer to obtain polymer composite material.

[0025] Furthermore, in step 1), the temperature range of the twin-screw extruder is set to 140-220℃.

[0026] Furthermore, in step 2), the rotor speed of the Haake torque rheometer is 30-120 r / min.

[0027] Furthermore, in step 2), the blending temperature is 150-200℃ and the blending time is 10-30min.

[0028] Furthermore, in step 2), the temperature range of the injection molding machine is set to 200-250℃.

[0029] Technical principle of the invention:

[0030] I. Principles of High-Performance Modified Heavy Calcium Carbonate Preparation Technology

[0031] 1. The role of core raw materials

[0032] Heavy calcium carbonate: As a matrix reinforcement phase, it has low cost and high hardness. After modification, it can form a good interfacial bond with polymers to achieve a stiffening effect while reducing the cost of composite materials.

[0033] Macromolecular additives: Coated on the surface of calcium carbonate, improving its surface polarity, enhancing compatibility with non-polar polypropylene (PP), and reducing interfacial defects.

[0034] Span 80: A nonionic surfactant that reduces the surface tension between calcium carbonate particles, promotes particle dispersion, prevents agglomeration, and enhances the spreadability of additives on the calcium carbonate surface.

[0035] Sodium hexametaphosphate: An inorganic dispersant that inhibits the agglomeration of calcium carbonate particles through electrostatic repulsion, further refining particle size and improving dispersion uniformity.

[0036] Silane coupling agent KH550: The two ends of the molecule contain polar groups (reacting with the hydroxyl groups on the surface of calcium carbonate) and non-polar groups (bonding with the PP molecular chain), which form a bridging effect, strengthen the interfacial bonding force between calcium carbonate and polymer, and improve the mechanical properties of composite materials.

[0037] Water: In the coupling agent treatment stage, it serves as a reaction medium to promote the hydrolysis of KH550 and ensure that the coupling agent is effectively grafted onto the calcium carbonate surface.

[0038] 2. The necessity of optimizing raw material usage and process parameters

[0039] Precise control of raw material dosage and process parameters is key to ensuring the modification effect. In the calcium carbonate pretreatment stage, the temperature needs to be controlled at 103-121℃, the vacuum degree ≤-0.08MPa, and the time 2-4h: if the drying is insufficient (the moisture content is too high), it will lead to uneven coating of subsequent additives; while excessive drying is unnecessary and will only waste energy.

[0040] In high-speed mixing modification, the amount of macromolecular additives should be 3.4-9.5% of the mass of calcium carbonate, Span 80 1.2-4.8%, and sodium hexametaphosphate 0.1-1%. The mixing temperature should be 62-75℃, the rotation speed 1200-1800 r / min, and the time 13-32 min. Insufficient additives will result in inadequate coating and limited improvement in compatibility; excessive additives will lead to excessive precipitation, affecting performance. Too low a rotation speed (<1200 r / min) will result in uneven mixing, while too high a rotation speed (>1800 r / min) will cause additive decomposition due to frictional heat. Matching the temperature and time can ensure that the additives melt and spread without degradation, ultimately achieving uniform coating of the additives on the calcium carbonate surface and initially improving dispersibility and compatibility.

[0041] When using coupling agent synergistic treatment, the dosage of KH550 is 0.6-2.8% of the calcium carbonate mass, and water is 0.5-0.9%. The mixing temperature is 76-88℃, the rotation speed is 800-1000 r / min, and the time is 6-10 min. Insufficient coupling agent will result in weak interfacial bonding; excessive coupling agent will form a "free layer," reducing mechanical properties. Too little water will not promote hydrolysis, while too much will lead to over-wetting of the system, affecting coating. Too low a temperature will result in incomplete reaction, while too high a temperature will cause the coupling agent to volatilize. Optimization of this step can strengthen the interfacial interaction between calcium carbonate and the polymer through chemical grafting, thereby improving the strength and toughness of the composite material.

[0042] In the secondary dispersion enhancement stage, the compressed air pressure needs to be controlled at 0.6-0.8 MPa, the feed rate at 5.3-9.9 kg / h, the classifier rotation speed at 3000-5000 r / min, and the temperature at ≤39℃. Too low a pressure will fail to refine the particles, while too high a pressure will cause a surge in energy consumption. The classifier rotation speed directly controls the particle size (too slow a speed results in overly coarse particles, while too fast a speed causes agglomeration of ultrafine particles). Temperatures exceeding 39℃ may lead to thermal decomposition of the additives or increase energy consumption. The optimized process can further refine the particles to the micron level, ensuring uniform coating of the additives and improving the subsequent mixing and dispersibility with the polymer.

[0043] 3. Technical Effects

[0044] The modified heavy calcium carbonate prepared by the above process has the characteristics of high surface polarity compatibility, excellent dispersibility, and strong interfacial bonding: after the surface is synergistically modified by multiple additives, its compatibility with PP is significantly improved, solving the problems of easy agglomeration and many interfacial defects of unmodified calcium carbonate; the ultrafine particle size (with secondary dispersion) can be uniformly dispersed in the polymer matrix, improving the tensile strength and elastic modulus of the material; compared with unmodified calcium carbonate, it can transfer stress more efficiently in composite materials, reduce local stress concentration under stress, and lay the foundation for subsequent synergistic effect with β nucleating agents.

[0045] II. Principles of Polymer Composite Material Preparation Technology

[0046] 1. The role of core raw materials

[0047] High-performance modified heavy calcium carbonate: As a reinforcing filler, it forms a strong interfacial bond with PP through optimized surface modification, which improves the rigidity of the material and enhances the impact toughness (especially at low temperatures) through uniform particle dispersion.

[0048] β-nucleating agent: It induces the orderly arrangement of PP molecular chains through intermolecular interactions, preferentially forming β crystals (which have higher toughness and low-temperature impact resistance compared to α crystals), while accelerating the crystallization rate and shortening the molding cycle.

[0049] Polypropylene (PP): As a matrix material, it provides the basic mechanical and processing properties of composite materials. Its crystallization morphology and rate are regulated by the synergistic effect of β nucleating agent and modified calcium carbonate.

[0050] 2. The necessity of optimizing raw material usage and process parameters

[0051] The amounts of raw materials must be strictly controlled as follows: 0.1-20 parts modified calcium carbonate, 0.1-5 parts β-nucleating agent, and 75-99.8 parts PP. Excessive use of modified calcium carbonate (>20 parts) will lead to agglomeration, thus reducing toughness; too little (<0.1 parts) will result in insignificant reinforcing effect. Insufficient β-nucleating agent (<0.1 parts) cannot induce sufficient β crystals; excessive use (>5 parts) will reduce performance due to its own agglomeration. Only within this range can the relationship between "reinforcement-toughening-cost" be balanced, ensuring maximum synergistic effect.

[0052] The temperature for twin-screw extrusion granulation needs to be set between 140-220℃: too low a temperature (<140℃) will result in insufficient melting of PP and uneven mixing; too high a temperature (>220℃) may cause PP degradation and a decrease in mechanical properties. A suitable temperature can ensure that modified calcium carbonate and PP are mixed evenly to form a stable composite masterbatch.

[0053] During the melt blending stage, the rotor speed of the Haake torque rheometer needs to be controlled at 30-120 r / min, the blending temperature at 150-200℃, and the blending time at 10-30 min. Too low a speed (<30 r / min) will result in uneven mixing; too high a speed (>120 r / min) will cause excessive shearing, potentially leading to PP degradation. Temperature and time must be matched to ensure uniform dispersion and non-decomposition of the β-nucleating agent, ultimately promoting its dispersion in the matrix and allowing it to fully interact with the PP molecular chains, inducing β-crystal formation.

[0054] 3. Technical Effects

[0055] The synergistic effect of modified calcium carbonate and β-nucleating agents is the core of improving the performance of composite materials:

[0056] Crystallization behavior regulation: β nucleating agent accelerates the crystallization rate of PP, and modified calcium carbonate further promotes the orderly arrangement of molecular chains through surface effect. The two work together to improve crystallinity and shorten the molding cycle.

[0057] Mechanical property optimization: The formation of β crystals improves the low-temperature impact strength, and the reinforcing effect of modified calcium carbonate improves the tensile strength, achieving toughening without sacrificing strength;

[0058] Cost-effectiveness: Modified calcium carbonate replaces part of PP, reducing material costs while maintaining high performance, thus solving the problem of "difficulty in balancing high performance and low cost" in traditional PP modification.

[0059] Compared with the prior art, the present invention has the following technical advantages:

[0060] (1) By adding a small amount of β nucleating agent, the present invention can change the crystallization behavior and crystallization morphology of PP, accelerate the crystallization rate of PP, shorten the production cycle, ensure product rigidity, and significantly improve its impact performance.

[0061] (2) The high-performance modified heavy calcium carbonate of the present invention can not only significantly improve the impact performance of the material under low temperature conditions and achieve the dual effects of toughening and strengthening, but also help reduce the material cost and has an irreplaceable role compared to other additives.

[0062] (3) This invention employs a strategy of using a stable and efficient β-nucleating agent and modified heavy calcium carbonate to toughen and modify PP. By fully leveraging the synergistic effect between the β-nucleating agent and modified heavy calcium carbonate, the crystallization behavior and morphology of PP are regulated, aiming to improve the impact performance of PP. This leads to the development of high-performance polymer composite materials. The elastic modulus and tensile properties are not reduced, but the room temperature and low temperature impact toughness of the material can be significantly improved, expanding its application range and potential. [Attached Image Description]

[0063] Figure 1 The graph shows the effect of the content of modified heavy calcium carbonate in the sample of Example 1 on the room temperature and low temperature impact strength of the polymer composite material.

[0064] Figure 2 The graph shows the effect of the modified heavy calcium carbonate content in the sample of Example 1 on the room temperature and low temperature impact strength of the modified heavy calcium carbonate / PP composite material.

Detailed Implementation Methods

[0065] To facilitate a better understanding of the present invention, the following examples are provided. These examples fall within the scope of protection of the present invention, but do not limit the scope of protection of the present invention.

[0066] In the embodiments, the preparation method of the functional macromolecular auxiliaries includes the following steps:

[0067] (1) Monomer premixing

[0068] Add 30-40 parts by weight of maleic anhydride, 20-30 parts of styrene, and 10-15 parts of acrylic acid to the reactor, add 50-80 parts of ethanol, and then stir at 42-48℃ and 200-300 r / min for 35-55 minutes until completely dissolved.

[0069] (2) Free radical polymerization

[0070] Nitrogen gas is introduced to replace the air, the temperature is raised to 83-96℃, and an ethanol solution of benzoyl peroxide (mass concentration 5-10%) is added dropwise. The reaction is carried out for 3.5-7.8 hours, during which ethylene glycol dimethacrylate is added to form a slightly cross-linked structure. The dropping rate of benzoyl peroxide is 1-2 mL / min, the reaction temperature is controlled at ±2℃, and the nitrogen flow rate is 0.6-1 L / min.

[0071] (3) Neutralization and hydrolysis treatment

[0072] After the reaction is complete, the temperature is lowered to 62-69℃, and a 5-10% sodium hydroxide solution is added to neutralize the anhydride groups for 32-58 minutes. The pH is then adjusted to 6.3-7, followed by the addition of deionized water (21-29% of the reaction system). The mixture is stirred at a hydrolysis temperature of 62-69℃ and a stirring speed of 300-500 r / min for 1-2 hours to hydrolyze some of the anhydride into carboxylates, thereby enhancing the hydrophilicity and obtaining the product.

[0073] (4) Drying and pulverizing

[0074] The product was transferred to a spray dryer, and macromolecular additive powder with a particle size of 5.2-19.8 μm was obtained by adjusting the atomization pressure to 0.3-0.5 MPa, the inlet temperature to 115-125℃, and the outlet temperature to 52-65℃.

[0075] Performance indicators and environmental evaluation of functional macromolecular additives:

[0076] Molecular weight > 30000 Da (GPC determination);

[0077] Hydroxyl content: 2.6-3.4 mmol / g (acid-base titration method);

[0078] Crosslinking density: 0.14-0.23 mmol / g (determined by swelling method);

[0079] Toxicity: Meets ISO10993 biocompatibility standards, LD50 > 5000 mg / kg (oral, rat).

[0080] The preparation principle of functional macromolecular auxiliaries:

[0081] I. Mechanism of Action of Core Raw Materials

[0082] Maleic anhydride, as a key monomer, is not only the basic unit of polymerization but also the core source of functional groups. Its anhydride groups can be converted into carboxylates during subsequent neutralization and hydrolysis. This conversion endows the auxiliaries with the ability to form polar bonds with the surface of heavy calcium carbonate, while also providing key sites for hydrophilicity regulation.

[0083] As a hydrophobic monomer, styrene can effectively balance the hydrophilicity and hydrophobicity of the polymer when copolymerized with maleic anhydride and acrylic acid. This balance helps to improve the adsorption stability of the additive on the calcium carbonate surface. At the same time, its own properties can enhance the rigidity of the polymer chain, thereby improving the mechanical resistance of the additive.

[0084] The addition of acrylic acid introduces a carboxyl functional group, which works synergistically with the anhydride group of maleic anhydride. After hydrolysis, it can further increase the hydrophilic sites, improve the dispersibility of the additive in the aqueous system, and provide more active centers for ionic bonding with the surface of calcium carbonate.

[0085] Benzoyl peroxide, as a free radical polymerization initiator, initiates monomer polymerization by generating free radicals through decomposition. Its dosage and dropping rate directly affect the polymerization rate and polymer molecular weight distribution, and are key to ensuring the controllability of the reaction.

[0086] Ethylene glycol dimethacrylate acts as a crosslinking agent, introducing a mildly crosslinked structure. This structure needs to be strictly controlled to avoid excessive rigidity caused by over-crosslinking, while also improving the polymer's heat resistance and shear strength through moderate crosslinking, so as to ensure that the additive does not easily decompose during the calcium carbonate modification process.

[0087] Sodium hydroxide is used to neutralize acid anhydride groups to form carboxylate salts. During the neutralization process, the time and solution concentration need to be controlled to adjust the pH of the system to a neutral or near-neutral range of 6.3-7. This not only avoids the corrosive effect of the acidic environment on the subsequent calcium carbonate modification, but also promotes the hydrolysis of acid anhydride and enhances the hydrophilicity of the additive.

[0088] Ethanol, as the initial reaction solvent, mainly functions to dissolve monomers and adjust the viscosity of the polymerization system, ensuring uniform dispersion of monomers and avoiding uneven product distribution caused by localized polymerization.

[0089] Deionized water is added during the hydrolysis stage. Its dosage and hydrolysis temperature work together to promote the hydrolysis of some acid anhydride groups into carboxylate salts, precisely controlling the hydrophilicity of the additives, and providing suitable system flowability for spray drying.

[0090] II. The Necessity and Importance of Optimizing Raw Material Usage and Process Parameters

[0091] Precise control of raw material dosage and process parameters is the core of ensuring the performance of additives, and its necessity is reflected in the following aspects:

[0092] 1. Synergistic balance of monomer ratio

[0093] The ratio of maleic anhydride (30-40 parts), styrene (20-30 parts), and acrylic acid (10-15 parts) directly determines the polymer's affinity / reluctance level and functional group density. If the maleic anhydride ratio is too high, the excessive hydrophilicity can easily lead to excessive adsorption and agglomeration of the additive on the calcium carbonate surface; if the styrene ratio is too high, the excessive hydrophobicity will reduce the compatibility with calcium carbonate. Optimizing the ratio can achieve a "polar-nonpolar" balance, ensuring that the additive can be firmly adsorbed on the calcium carbonate surface and uniformly dispersed in the application system (such as PP).

[0094] 2. Precise control of crosslinking degree

[0095] The amount of ethylene glycol dimethacrylate and the reaction conditions determine the formation of a mildly cross-linked structure. Excessive cross-linking leads to excessive rigidity of the additive, making it difficult to spread on the calcium carbonate surface; insufficient cross-linking results in poor thermal stability and easy decomposition during processing. By controlling the timing of its addition and the reaction temperature (±2℃), a moderately cross-linked network can be formed, balancing the flexibility and stability of the additive.

[0096] 3. Ensuring the stability of polymerization reaction parameters

[0097] The polymerization rate is controlled by the dropping rate (1-2 mL / min) and concentration (5-10%) of benzoyl peroxide: too fast a rate will lead to intense local exothermic reaction and cause a broadening of the molecular weight distribution; too slow a rate will result in incomplete reaction and residual monomers that affect the purity of the additives.

[0098] Nitrogen flow rate (0.6-1L / min) and temperature control (83-96℃): Nitrogen isolates oxygen to prevent free radicals from being oxidized, and a stable temperature ensures that the polymerization reaction proceeds uniformly, avoiding abnormal chain transfer or termination reaction caused by temperature fluctuations.

[0099] 4. Precise control of neutralization and hydrolysis

[0100] The concentration of sodium hydroxide solution (5-10%) and neutralization time (32-58 min) determine the degree of neutralization of the anhydride groups, while the pH value (6.3-7) ensures a balance between the carboxylate and unhydrolyzed anhydride ratio. The amount of deionized water (21-29%) and hydrolysis temperature (62-69℃) control the depth of hydrolysis; excessive hydrolysis leads to excessive hydrophilicity, while insufficient hydrophilicity results in inadequate hydrophilicity. Optimizing this step can achieve biphase compatibility of the additive in both aqueous and organic phase systems.

[0101] 5. Effects of drying parameters on powder properties

[0102] The atomization pressure (0.3-0.5 MPa) and inlet / outlet temperature (115-125℃ / 52-65℃) of spray drying directly determine the powder particle size (5.2-19.8 μm) and morphology. Excessive pressure or improper temperature can lead to powder agglomeration or uneven particle size, affecting its dispersion efficiency during calcium carbonate modification. Optimizing these parameters can yield powders with uniform particle size, ensuring maximum contact area with calcium carbonate particles.

[0103] III. Technical Effects and Unexpected Advantages

[0104] 1. Core Technology Effects

[0105] The mildly cross-linked structure endows the additive with excellent thermal stability (resistance to high temperatures during calcium carbonate processing) and shear resistance, solving the problems of easy decomposition and dispersion failure of traditional linear additives.

[0106] The synergistic effect of carboxylates and unhydrolyzed anhydrides enables the additives to both firmly bind to the calcium carbonate surface through ionic bonds (polar effect) and be compatible with organic matrices (such as PP) through styrene segments (non-polar effect), thus achieving interfacial bridging function and significantly improving the dispersibility of calcium carbonate and the mechanical properties of composite materials.

[0107] The controllable particle size of the powder (5.2-19.8μm) ensures the compatibility between the additives and calcium carbonate particles, reduces agglomeration, and improves the modification efficiency.

[0108] 2. Unexpected technical effects

[0109] The synergistic effect of mild cross-linking structure and hydrophilic-hydrophobic balance enables the additive to maintain the fluidity of the composite material even at high filler content, overcoming the problem of the dramatic increase in system viscosity caused by traditional additives at high filler content.

[0110] The dynamic equilibrium between partially hydrolyzed carboxylate groups and residual anhydrides endows the additives with adaptability to systems with different pH values, thus expanding their application range.

[0111] The powder obtained by spray drying has a porous structure. When mixed with calcium carbonate, it can reduce dust flying through the pores, improve the production environment, and improve the uniformity of modification.

[0112] The method for preparing the high-performance modified heavy calcium carbonate includes the following steps:

[0113] (1) Pretreatment of calcium carbonate

[0114] Heavy calcium carbonate (d50 = 2.1-5.2 μm) was dried at a temperature of 103-121℃ and a vacuum degree of ≤-0.08MPa for 2-4 hours to remove surface adsorbed water.

[0115] (2) High-speed hybridization modification

[0116] The dried calcium carbonate is put into a high-speed mixer (with a bag filter installed at the outlet, dust collection rate ≥99%), and 3.4-9.5% of macromolecular additives, 1.2-4.8% of Span 80 and 0.1-1% of sodium hexametaphosphate are added. The mixture is mixed for 13-32 minutes at a mixing temperature of 62-75℃ and a speed of 1200-1800 r / min.

[0117] (3) Coupling agent synergistic treatment

[0118] Add 0.6-2.8% by weight of calcium carbonate silane coupling agent KH550 and 0.5-0.9% by weight of calcium carbonate deionized water (to promote hydrolysis). Mix for 6-10 minutes at a mixing temperature of 76-88℃ and a rotation speed of 800-1000 r / min to allow the coupling agent to be fully hydrolyzed and react with the surface of calcium carbonate to obtain the material.

[0119] (4) Secondary dispersion enhancement

[0120] The material is transferred to an air jet mill (with a bag filter installed at the outlet) for ultrafine grinding under compressed air of 0.6-0.8MPa, further refining the particles and uniformly coating them with macromolecular additives. Process parameters: feed rate 5.3-9.9kg / h, classifier speed 3000-5000r / min, grinding temperature ≤39℃.

[0121] (5) Drying and sieving

[0122] Finally, dry at 60-80℃ for 1-2 hours and pass through an 800-1200 mesh sieve to obtain high-performance modified heavy calcium carbonate.

[0123] The application of high-performance modified heavy calcium carbonate in polymer composites, the raw materials by weight include: 0.1-20 parts high-performance modified heavy calcium carbonate, 0.1-5 parts β nucleating agent, and 75-99.8 parts polypropylene.

[0124] The β-nucleating agent is one or a mixture of several of the following: rare earth elements (WBG, WBG-II), amides (TMB-5, TATA, DCHT, DCNDCA), dicarboxylic acids (CA-19, NBDA30), fused ring compounds (E3B, TPDT, MBIM), and polymers (PBDPS, PDAPs, ABS).

[0125] The application of high-performance modified heavy calcium carbonate in polymer composites includes the following steps:

[0126] (1) Weigh high-performance modified heavy calcium carbonate and polypropylene by mass, mix them and add them to a twin-screw extruder for mixing. The high-performance modified heavy calcium carbonate / polypropylene composite masterbatch is prepared by extrusion granulation.

[0127] (2) Add β nucleating agent to high-performance modified heavy calcium carbonate / polypropylene composite masterbatch, mix and melt blend in Haake torque rheometer to obtain polymer composite material.

[0128] In step (1), the temperature range of the twin-screw extruder is set to 140-220℃.

[0129] In step (2), the rotor speed of the Haake torque rheometer is 30-120 r / min, the blending temperature is 150-200℃, and the blending time is 10-30 min; the temperature range of the injection molding machine is set to 200-250℃.

[0130] To make the present invention more fully disclosed, the present invention will be described below through more specific embodiments.

[0131] Example 1

[0132] The preparation method of functional macromolecular auxiliaries includes the following steps:

[0133] (1) Monomer premixing

[0134] By mass, 36 parts maleic anhydride, 25 parts styrene, and 13 parts acrylic acid were added to the reactor, along with 64 parts ethanol. The mixture was then stirred at 45°C and 300 r / min for 35 min until completely dissolved.

[0135] (2) Free radical polymerization

[0136] Nitrogen gas was introduced to replace the air, the temperature was raised to 90°C, and an ethanol solution of benzoyl peroxide (mass concentration 8%) was added dropwise. The reaction was carried out for 5.6 h, during which ethylene glycol dimethacrylate was added to form a slightly cross-linked structure. The dropping rate of the benzoyl peroxide was 1.3 mL / min, the reaction temperature was controlled at ±2°C, and the nitrogen flow rate was 0.8 L / min.

[0137] (3) Neutralization and hydrolysis treatment

[0138] After the reaction was completed, the temperature was lowered to 65℃, and 8.2% sodium hydroxide solution was added to neutralize the anhydride groups for 48 min. The pH was adjusted to 6.8, and then deionized water (accounting for 25% of the reaction system) was added. The mixture was stirred at a hydrolysis temperature of 66℃ and a stirring speed of 400 r / min for 1.5 h to hydrolyze some of the anhydride into carboxylate, thereby enhancing the hydrophilicity and obtaining the product.

[0139] (4) Drying and pulverizing

[0140] The product was transferred to a spray dryer, and macromolecular additive powder with a particle size of 14.3 μm was obtained by adjusting the atomization pressure to 0.4 MPa, the inlet temperature to 120 °C, and the outlet temperature to 60 °C.

[0141] The method for preparing the high-performance modified heavy calcium carbonate includes the following steps:

[0142] (1) Pretreatment of calcium carbonate

[0143] Heavy calcium carbonate (d50 = 3.2 μm) was dried at 115 °C and under a vacuum of ≤ -0.08 MPa for 3 h to remove surface adsorbed water.

[0144] (2) High-speed hybridization modification

[0145] The dried calcium carbonate was put into a high-speed mixer (with a bag filter installed at the outlet, dust collection rate ≥99%), and 6.3% of the calcium carbonate mass of macromolecular additives, 3% of the calcium carbonate mass of Span 80 and 0.6% of the calcium carbonate mass of sodium hexametaphosphate were added. The mixture was mixed for 20 minutes at a mixing temperature of 70℃ and a rotation speed of 1600 r / min.

[0146] (3) Coupling agent synergistic treatment

[0147] Add 1.5% by weight of calcium carbonate silane coupling agent KH550 and 0.7% by weight of calcium carbonate deionized water (to promote hydrolysis). Mix at 80℃ and 900 r / min for 8 min to allow the coupling agent to fully hydrolyze and react with the calcium carbonate surface to obtain the material.

[0148] (4) Secondary dispersion enhancement

[0149] The material is transferred to an air jet mill (with a bag filter installed at the outlet) for ultrafine grinding under 0.7MPa compressed air to further refine the particles and uniformly coat them with macromolecular additives. Process parameters: feed rate 8.1kg / h, classifier speed 4000r / min, grinding temperature 38℃.

[0150] (5) Drying and sieving

[0151] Finally, it was dried at 68℃ for 1.6 hours and passed through a 1000-mesh sieve to obtain high-performance modified heavy calcium carbonate. The oil absorption value was 14.3 g / 100 g, the activation degree was 98.1% (sedimentation volume method), the whiteness was 97.2%, and the dispersibility (SEM observation) showed that the single particles were uniformly coated and there was no agglomeration.

[0152] The application of high-performance modified heavy calcium carbonate in polymer composites, the raw materials include: high-performance modified heavy calcium carbonate, β nucleating agent, polypropylene (PP), the raw material dosage is shown in Table 1.

[0153] The β-nucleating agent is a rare earth element (WBG-Ⅱ).

[0154] The application of high-performance modified heavy calcium carbonate in polymer composites includes the following steps:

[0155] (1) Weigh high-performance modified heavy calcium carbonate and polypropylene, mix them and add them to a twin-screw extruder for mixing. The high-performance modified heavy calcium carbonate / polypropylene composite masterbatch is prepared by extrusion granulation.

[0156] (2) Add β nucleating agent to high-performance modified heavy calcium carbonate / polypropylene composite masterbatch, mix and melt blend in Haake torque rheometer to obtain polymer composite material.

[0157] The extruder temperature in step (1) is set to: 150℃, 180℃, 190℃, 200℃, 200℃, 210℃, 200℃.

[0158] In step (2), the rotor speed of the Haake torque rheometer is 60 r / min, the blending temperature is 180℃, and the blending time is 10 mins; the injection molding machine temperature is set to 215℃, 220℃, 215℃.

[0159] The polymer composite material obtained in step (2) was crushed and then injected into standard test strips for testing relevant parameters, as shown in Tables 1 and 2. Figure 1 , 2 ,in Figure 2 No β-nucleating agent is used; therefore, no β-nucleating agent is added in the corresponding preparation method.

[0160] Table 1. Non-isothermal crystallization and melting parameters of the sample from Example 1

[0161]

[0162] Note: a T c on The initial crystallization temperature;

[0163] b T c p, crystallization peak temperature;

[0164] c △T=T m pT c p, supercooling;

[0165] d S i The slope of the crystallization peak initiation;

[0166] e T m α α melting peak temperature;

[0167] f T m β β melting peak temperature;

[0168] Relative content of β crystals.

[0169] Table 2 Tensile properties of the sample from Example 1

[0170]

[0171] The following conclusions can be drawn from Table 1:

[0172] (1) Increased crystallization temperature significantly improves nucleation effect

[0173] Compared with pure PP, the composite material with modified heavy calcium carbonate and β nucleating agent (WBG-Ⅱ) showed significantly higher initial crystallization temperature and crystallization peak temperature (e.g., the initial crystallization temperature of the 0.5wt% modified heavy calcium carbonate sample was 114.7℃, higher than that of pure PP at 106.3℃). This indicates that the modified heavy calcium carbonate and β nucleating agent synergistically promote PP crystallization, reduce supercooling (from 42.5℃ to 36.4-37.4℃), and accelerate the crystallization process.

[0174] (2) β-crystal phase formation enhances toughness potential.

[0175] Pure PP without β-phase The samples with added modified heavy calcium carbonate all showed a β melting peak ( f T m β =135.6-135.9℃), relative content of β crystals The content is around 30% (reaching 33.0% in a 4.0 wt% modified heavy calcium carbonate sample). The formation of the β-phase typically improves the toughness of the material, which corresponds to the subsequent mechanical property results.

[0176] (3) Increased crystallinity and more stable structure

[0177] The crystallinity of the composite material (29.2%→35.1%-36.9%) was higher than that of pure PP, indicating that the addition of modified heavy calcium carbonate promoted the orderly arrangement of PP molecular chains, improved crystal integrity, and may have enhanced the rigidity of the material.

[0178] The following conclusions can be drawn from Table 2:

[0179] From the tensile property data, the polypropylene composites with modified heavy calcium carbonate showed certain regular changes in key indicators compared to pure polypropylene (PP). Regarding the elastic modulus, the values ​​of each composite sample (1099.1-1133.4 MPa) were close to those of pure PP (1133.0 MPa), with small fluctuations, indicating that the addition of modified heavy calcium carbonate did not significantly affect the rigidity of the material. As for the yield strength, the values ​​of the composites (48.7-50.4 MPa) were slightly lower than the 52.5 MPa of pure PP, but remained generally stable without a significant decrease, indicating that the basic strength of the material was well preserved.

[0180] The changes in elongation at break were more pronounced. The sample with 4.0 wt% modified heavy calcium carbonate achieved an elongation at break of 102.7%, significantly higher than the 79.8% of pure PP. While other samples showed varying degrees of increase and decrease, the 4.0 wt% sample generally performed best, indicating that the material's ductility was effectively improved at this ratio. The area under the stress-strain curve reflects the material's energy absorption capacity. The 4.0 wt% sample had the highest area under stress at 12.09 GPa, indicating it absorbed more energy and exhibited the best toughness under stress.

[0181] In summary, the addition of 4.0 wt% modified heavy calcium carbonate significantly improved the elongation at break and energy absorption capacity of the composite material while maintaining stable basic strength (elastic modulus and yield strength), achieving a good balance between strength and toughness. The tensile properties were optimal under this ratio.

[0182] Depend on Figure 1 The following conclusions were drawn from the analysis:

[0183] (1) Effect of temperature on impact performance: The impact strength at room temperature (23℃) is generally higher than that at low temperature (-10℃), which is consistent with the low-temperature brittleness characteristics of polymer materials. However, the performance gap between low temperature and room temperature may be narrowed after adding modified heavy calcium carbonate, indicating that modified heavy calcium carbonate helps to improve low-temperature toughness.

[0184] (2) Effect of modified heavy calcium carbonate content: As the modified heavy calcium carbonate content increases, the peak value of impact strength is at 4.0 wt% (consistent with the best toughness of the 4.0 wt% sample in Table 2), indicating that the material has the strongest impact resistance at this ratio, which is consistent with the result of the highest β crystal phase content (Table 1).

[0185] Based on Tables 1 and 2 above and Figure 1 Conclusion Analysis:

[0186] (1) Crystallization and structural optimization: The synergistic effect of modified heavy calcium carbonate and β nucleating agent WBG-Ⅱ significantly improves the crystallization temperature and crystallinity of PP, promotes the formation of β crystal phase, and lays the structural foundation for improving mechanical properties.

[0187] (2) Optimal mechanical properties: The addition of 4.0wt% modified heavy calcium carbonate makes the composite material exhibit the best performance in terms of elongation at break, energy absorption capacity and impact strength, achieving a balance between strength and toughness.

[0188] (3) Application value: This modification scheme can effectively improve the crystallization behavior and mechanical properties of PP, and is especially suitable for polymer composite materials with high toughness requirements (such as packaging, automotive parts, etc.).

[0189] Example 2

[0190] The preparation method of functional macromolecular auxiliaries includes the following steps:

[0191] (1) Monomer premixing

[0192] By mass, 32 parts maleic anhydride, 21 parts styrene, and 12 parts acrylic acid were added to the reactor, along with 54 parts ethanol. The mixture was then stirred at 43°C and 200 r / min for 54 min until completely dissolved.

[0193] (2) Free radical polymerization

[0194] Nitrogen gas was introduced to replace the air, the temperature was raised to 84°C, and an ethanol solution of benzoyl peroxide (mass concentration 5.6%) was added dropwise. The reaction was carried out for 7.5 h, during which ethylene glycol dimethacrylate was added to form a slightly cross-linked structure. The dropping rate of the benzoyl peroxide was 1.2 mL / min, the reaction temperature was controlled at ±2°C, and the nitrogen flow rate was 0.7 L / min.

[0195] (3) Neutralization and hydrolysis treatment

[0196] After the reaction was completed, the temperature was lowered to 62℃, and a 5.6% sodium hydroxide solution was added to neutralize the anhydride groups for 55 min. The pH was adjusted to 6.8, and then deionized water (accounting for 22% of the reaction system) was added. The mixture was stirred for 2 h at a hydrolysis temperature of 63℃ and a stirring speed of 300 r / min to hydrolyze some of the anhydride into carboxylate, thereby enhancing the hydrophilicity and obtaining the product.

[0197] (4) Drying and pulverizing

[0198] The product was transferred to a spray dryer, and macromolecular additive powder with a particle size of 7.1 μm was obtained by adjusting the atomization pressure to 0.3 MPa, the inlet temperature to 115 °C, and the outlet temperature to 52 °C.

[0199] The method for preparing the high-performance modified heavy calcium carbonate includes the following steps:

[0200] (1) Pretreatment of calcium carbonate

[0201] Heavy calcium carbonate (d50 = 2.3 μm) was dried at 106 °C and under a vacuum of ≤ -0.08 MPa for 3.8 h to remove surface adsorbed water.

[0202] (2) High-speed hybridization modification

[0203] The dried calcium carbonate was put into a high-speed mixer (with a bag filter installed at the outlet, dust collection rate ≥99%), and 3.7% of the calcium carbonate mass of macromolecular additives, 1.4% of the calcium carbonate mass of Span 80 and 0.2% of the calcium carbonate mass of sodium hexametaphosphate were added. The mixture was mixed for 32 minutes at a mixing temperature of 64℃ and a rotation speed of 1200 r / min.

[0204] (3) Coupling agent synergistic treatment

[0205] Add 0.9% by weight of calcium carbonate silane coupling agent KH550 and 0.7% by weight of calcium carbonate deionized water (to promote hydrolysis). Mix for 10 minutes at a mixing temperature of 80℃ and a rotation speed of 800 r / min to allow the coupling agent to be fully hydrolyzed and react with the surface of calcium carbonate to obtain the material.

[0206] (4) Secondary dispersion enhancement

[0207] The material is transferred to an air jet mill (with a bag filter installed at the outlet) for ultrafine grinding under 0.6MPa compressed air to further refine the particles and uniformly coat them with macromolecular additives. Process parameters: feed rate 5.8kg / h, classifier speed 3000r / min, grinding temperature 39℃.

[0208] (5) Drying and sieving

[0209] Finally, it was dried at 62℃ for 1.8 hours and passed through an 800-mesh sieve to obtain high-performance modified heavy calcium carbonate.

[0210] The application of high-performance modified heavy calcium carbonate in polymer composites, the raw materials by weight include: 10 parts high-performance modified heavy calcium carbonate, 2.5 parts β nucleating agent, and 87.5 parts polypropylene.

[0211] The β-nucleating agent is an amide (TMB-5).

[0212] The application of high-performance modified heavy calcium carbonate in polymer composites includes the following steps:

[0213] (1) Weigh high-performance modified heavy calcium carbonate and polypropylene by mass, mix them and add them to a twin-screw extruder for mixing. The high-performance modified heavy calcium carbonate / polypropylene composite masterbatch is prepared by extrusion granulation.

[0214] (2) Add β nucleating agent to high-performance modified heavy calcium carbonate / polypropylene composite masterbatch, mix and melt blend in Haake torque rheometer to obtain polymer composite material.

[0215] The extruder temperature in step (1) is set to: 160℃, 190℃, 200℃, 210℃, 210℃, 220℃, 210℃.

[0216] In step (2), the rotor speed of the Haake torque rheometer is 50 r / min, the blending temperature is 190℃, the blending time is 15 min, and the injection molding machine temperature is set to 225℃, 230℃, 225℃.

[0217] Example 3

[0218] The preparation method of functional macromolecular auxiliaries includes the following steps:

[0219] (1) Monomer premixing

[0220] By mass, 38 parts maleic anhydride, 28.5 parts styrene, and 14 parts acrylic acid were added to the reactor, along with 78 parts ethanol. The mixture was then stirred at 47°C and 300 r / min for 35 min until completely dissolved.

[0221] (2) Free radical polymerization

[0222] Nitrogen gas was introduced to replace the air, the temperature was raised to 92°C, and an ethanol solution of benzoyl peroxide (mass concentration 8%) was added dropwise. The reaction was carried out for 4.5 h, during which ethylene glycol dimethacrylate was added to form a slightly cross-linked structure. The dropping rate of the benzoyl peroxide was 2 mL / min, the reaction temperature was controlled at ±2°C, and the nitrogen flow rate was 0.9 L / min.

[0223] (3) Neutralization and hydrolysis treatment

[0224] After the reaction was completed, the temperature was lowered to 65℃, and a 6.8% sodium hydroxide solution was added to neutralize the anhydride groups for 40 min. The pH was adjusted to 6.9, and then deionized water (accounting for 27% of the reaction system) was added. The mixture was stirred at a hydrolysis temperature of 68℃ and a stirring speed of 500 r / min for 1 h to hydrolyze some of the anhydride into carboxylate, thereby enhancing the hydrophilicity and obtaining the product.

[0225] (4) Drying and pulverizing

[0226] The product was transferred to a spray dryer, and macromolecular additive powder with a particle size of 19.2 μm was obtained by adjusting the atomization pressure to 0.5 MPa, the inlet temperature to 125 °C, and the outlet temperature to 64 °C.

[0227] The method for preparing the high-performance modified heavy calcium carbonate includes the following steps:

[0228] (1) Pretreatment of calcium carbonate

[0229] Heavy calcium carbonate (d50=5μm) was dried at 118℃ and under a vacuum of ≤-0.08MPa for 2.1h to remove surface adsorbed water.

[0230] (2) High-speed hybridization modification

[0231] The dried calcium carbonate was put into a high-speed mixer (with a bag filter installed at the outlet, dust collection rate ≥99%), and 9% of the calcium carbonate mass of macromolecular additives, 4.5% of the calcium carbonate mass of Span 80 and 1% of the calcium carbonate mass of sodium hexametaphosphate were added. The mixture was mixed for 14 minutes at a mixing temperature of 72℃ and a rotation speed of 1800 r / min.

[0232] (3) Coupling agent synergistic treatment

[0233] Add 2.5% by weight of calcium carbonate silane coupling agent KH550 and 0.9% by weight of calcium carbonate deionized water (to promote hydrolysis). Mix for 7 minutes at a mixing temperature of 83℃ and a rotation speed of 1000 r / min to allow the coupling agent to be fully hydrolyzed and react with the surface of calcium carbonate to obtain the material.

[0234] (4) Secondary dispersion enhancement

[0235] The material is transferred to an air jet mill (with a bag filter installed at the outlet) for ultrafine grinding under 0.7MPa compressed air to further refine the particles and uniformly coat them with macromolecular additives. Process parameters: feed rate 9.4kg / h, classifier speed 4000r / min, grinding temperature 38℃.

[0236] (5) Drying and sieving

[0237] Finally, it was dried at 75℃ for 1.2 hours and passed through a 1200-mesh sieve to obtain high-performance modified heavy calcium carbonate.

[0238] The application of high-performance modified heavy calcium carbonate in polymer composites, the raw materials by weight include: 15 parts high-performance modified heavy calcium carbonate, 3.8 parts β nucleating agent, and 81.2 parts polypropylene.

[0239] The β-nucleating agent is a dicarboxylic acid (NBDA30).

[0240] The application of high-performance modified heavy calcium carbonate in polymer composites includes the following steps:

[0241] (1) Weigh high-performance modified heavy calcium carbonate and polypropylene by mass, mix them and add them to a twin-screw extruder for mixing. The high-performance modified heavy calcium carbonate / polypropylene composite masterbatch is prepared by extrusion granulation.

[0242] (2) Add β nucleating agent to high-performance modified heavy calcium carbonate / polypropylene composite masterbatch, mix and melt blend in Haake torque rheometer to obtain polymer composite material.

[0243] The extruder temperature in step (1) is set to: 145℃, 175℃, 185℃, 195℃, 195℃, 205℃, 195℃.

[0244] In step (2), the rotor speed of the Haake torque rheometer is 90 r / min, the blending temperature is 175℃, the blending time is 25 min, and the injection molding machine temperature is set to 210℃, 215℃, 210℃.

[0245] Example 4

[0246] The application of high-performance modified heavy calcium carbonate in polymer composites, the raw materials by weight include: 20 parts high-performance modified heavy calcium carbonate, 5 parts β nucleating agent, and 75 parts polypropylene.

[0247] The preparation process of the high-performance modified heavy calcium carbonate is the same as in Example 1.

[0248] The β-nucleating agent is a polymer (PBDPS).

[0249] The application of high-performance modified heavy calcium carbonate in polymer composites includes the following steps:

[0250] (1) Weigh high-performance modified heavy calcium carbonate and polypropylene by mass, mix them and add them to a twin-screw extruder for mixing. The high-performance modified heavy calcium carbonate / polypropylene composite masterbatch is prepared by extrusion granulation.

[0251] (2) Add β nucleating agent to high-performance modified heavy calcium carbonate / polypropylene composite masterbatch, mix and melt blend in Haake torque rheometer to obtain polymer composite material.

[0252] The extruder temperature in step (1) is set to: 155℃, 185℃, 195℃, 205℃, 205℃, 215℃, 205℃.

[0253] In step (2), the rotor speed of the Haake torque rheometer is 100 r / min, the blending temperature is 185℃, the blending time is 20 min, and the injection molding machine temperature is set to 220℃, 225℃, 220℃.

[0254] Example 5

[0255] The application of high-performance modified heavy calcium carbonate in polymer composites, the raw materials by weight include: 5 parts high-performance modified heavy calcium carbonate, 1 part β nucleating agent, and 94 parts polypropylene.

[0256] The preparation process of the high-performance modified heavy calcium carbonate is the same as in Example 1.

[0257] The β-nucleating agent is a fused ring compound (MBIM).

[0258] The application of high-performance modified heavy calcium carbonate in polymer composites includes the following steps:

[0259] (1) Weigh high-performance modified heavy calcium carbonate and polypropylene by mass, mix them and add them to a twin-screw extruder for mixing. The high-performance modified heavy calcium carbonate / polypropylene composite masterbatch is prepared by extrusion granulation.

[0260] (2) Add β nucleating agent to high-performance modified heavy calcium carbonate / polypropylene composite masterbatch, mix and melt blend in Haake torque rheometer to obtain polymer composite material.

[0261] The extruder temperature in step (1) is set to: 140℃, 170℃, 180℃, 190℃, 190℃, 200℃, 190℃.

[0262] In step (2), the rotor speed of the Haake torque rheometer is 75 r / min, the blending temperature is 170℃, the blending time is 30 min, and the injection molding machine temperature is set to 205℃, 210℃, 205℃.

[0263] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0264] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing high-performance modified heavy calcium carbonate, characterized in that, Includes the following steps: (1) Pretreatment of calcium carbonate Heavy calcium carbonate was dried at a temperature of 103-121℃ and a vacuum degree of ≤-0.08MPa for 2-4 hours. (2) High-speed hybridization modification The dried calcium carbonate is put into a high-speed mixer, and 3.4-9.5% of the calcium carbonate mass of macromolecular auxiliary agent, 1.2-4.8% of the calcium carbonate mass of Span 80 and 0.1-1% of the calcium carbonate mass of sodium hexametaphosphate are added. The mixture is mixed for 13-32 minutes at a mixing temperature of 62-75℃ and a speed of 1200-1800 r / min. (3) Coupling agent synergistic treatment Add 0.6-2.8% (by weight of calcium carbonate) of silane coupling agent KH550 and 0.5-0.9% (by weight of calcium carbonate) of water, and mix for 6-10 minutes at a mixing temperature of 76-88℃ and a rotation speed of 800-1000 r / min to obtain the material. (4) Secondary dispersion enhancement The material is transferred to an air jet mill and ultra-finely pulverized under compressed air of 0.6-0.8MPa to further refine the particles and uniformly coat them with macromolecular additives. Process parameters: feed rate 5.3-9.9kg / h, classifier speed 3000-5000r / min, pulverization temperature ≤39℃. (5) Drying and sieving Finally, dry at 60-80℃ for 1-2 hours and pass through an 800-1200 mesh sieve to obtain high-performance modified heavy calcium carbonate.

2. The method for preparing high-performance modified heavy calcium carbonate according to claim 1, characterized in that, A bag filter is installed at the outlet of the high-speed mixer described in step (2), with a dust collection rate of ≥99%.

3. The method for preparing high-performance modified heavy calcium carbonate according to claim 1, characterized in that, The outlet of the airflow pulverizer described in step (4) is equipped with a bag filter.

4. A high-performance modified heavy calcium carbonate prepared by the method according to any one of claims 1-3.

5. An application of the high-performance modified heavy calcium carbonate according to claim 4 in polymer composite materials, characterized in that, The raw materials, by weight, include: 0.1-20 parts high-performance modified heavy calcium carbonate, 0.1-5 parts β-nucleating agent, and 75-99.8 parts polypropylene.

6. The application of the high-performance modified heavy calcium carbonate according to claim 5 in polymer composite materials, characterized in that, The β-nucleating agent includes one or a mixture of several of the following: rare earth elements, amides, dicarboxylic acids, fused ring compounds, and polymers.

7. The application of the high-performance modified heavy calcium carbonate according to claim 5 or 6 in polymer composite materials, characterized in that, The application of high-performance modified heavy calcium carbonate in polymer composites includes the following steps: 1) Weigh high-performance modified heavy calcium carbonate and polypropylene by weight, mix them, add them to a twin-screw extruder, and then granulate them to obtain high-performance modified heavy calcium carbonate / polypropylene composite masterbatch. 2) Add β nucleating agent to high-performance modified heavy calcium carbonate / polypropylene composite masterbatch, mix and melt blend in Haake torque rheometer to obtain polymer composite material.

8. The application of the high-performance modified heavy calcium carbonate according to claim 7 in polymer composite materials, characterized in that, In step 1), the temperature range of the twin-screw extruder is set to 140-220℃.

9. The application of the high-performance modified heavy calcium carbonate according to claim 6 in polymer composite materials, characterized in that, In step 2), the rotor speed of the Haake torque rheometer is 30-120 r / min, the blending temperature is 150-200℃, and the blending time is 10-30 min.

10. The application of the high-performance modified heavy calcium carbonate according to claim 6 in polymer composite materials, characterized in that, In step 2), the temperature range of the injection molding machine is set to 200-250℃.

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