Preparation method and application of high oil absorption value heavy calcium carbonate powder

Abstract

The present application relates to the technical field of non-metallic mineral processing, and particularly relates to a preparation method and application of high oil absorption value heavy calcium carbonate powder. The preparation method of the high oil absorption value heavy calcium carbonate powder is as follows: after raw material pretreatment, the raw material is transferred into a ring roller mill, and is processed in three zones, i.e., a low-speed crushing zone, an anchor reaction zone in which a pretreatment composite additive is added, and a solidification zone. Then, the processed product is classified by a double-stage turbine classifier and is subjected to low-temperature plasma treatment, so as to obtain the high oil absorption value heavy calcium carbonate powder. The proportion of particles with a particle size of 2 microns or less is greater than or equal to 65%, and the oil absorption value is greater than or equal to 90 g / 100 g. When the high oil absorption value heavy calcium carbonate powder is applied in PVC products, not only is the interface compatibility good, but also the powder surface interface bonding force is high, and the high oil absorption value heavy calcium carbonate powder has a good effect of replacing light calcium carbonate.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of non-metallic mineral processing, and in particular to a preparation method and application of high-oil-value heavy calcium carbonate powder. BACKGROUND

[0002] Heavy calcium carbonate, referred to as heavy calcium, is a kind of powder material prepared from natural carbonate minerals, mainly calcite, marble, chalk and limestone, through crushing, grinding and grading processing. The mechanical grinding process has the characteristics of small pollution and low energy consumption, and is currently vigorously promoted by the industry, gradually replacing light calcium carbonate since 2018. Ordinary heavy calcium carbonate adopts a vertical mill or a ball mill or a wet process superfine powder, and realizes high surface interface action on the powder surface by obtaining a higher specific surface area, while ignoring the influence of the micro-surface morphology and chemical groups of the powder on adsorption and surface interface action. As a result, the cost is greatly increased, but the effect is not satisfactory.

[0003] In the fields of plastics and coatings, high-oil-value heavy calcium carbonate powder can significantly improve the adsorption performance of plasticizers, but the traditional preparation method has problems such as uneven distribution of additives and unstable oil absorption value. Ordinary heavy calcium carbonate which simply depends on the particle size control performance mode cannot realize the substitution of light calcium carbonate with higher surface function at low cost.

[0004] Therefore, it is of great significance to develop a heavy calcium carbonate powder with high surface action force and relatively low price. SUMMARY

[0005] In order to develop heavy calcium carbonate powder with high surface action force and high oil absorption value, and solve the problems of high energy consumption, uneven modification and low fine powder rate in the traditional process, the application provides a preparation method and application of high-oil-value heavy calcium carbonate powder.

[0006] In a first aspect, the application provides a preparation method of high-oil-value heavy calcium carbonate powder, which adopts the following technical scheme:

[0007] S1, raw material pretreatment: crushing the stone block to a particle size of less than or equal to 5 mm; spraying liquid nitrogen on the crushed material at-50 DEG C to-30 DEG C for 5-10 min to induce the generation of micro-cracks, and obtaining pretreated stone block raw material;

[0008] S2, inputting the pretreated stone block raw material into a ring roller mill to complete the gradient treatment in three zones: low-speed crushing zone: linear speed of 12-15 m / s, residence time of 3-5 s; anchor reaction zone: adding pretreated composite additives, linear speed of 15-18 m / s, residence time of 8-10 s; solidification zone: linear speed of 18-20 m / s, residence time of 10-15 s;

[0009] S3 is classified by a double-stage turbo classifier, and the content of particles with a particle size less than 2 μm in the classified powder is controlled to be greater than or equal to 65%;

[0010] S4 is a low-temperature plasma treatment on the classified powder to obtain high oil absorption value heavy calcium carbonate powder.

[0011] Through the above scheme, the synergistic effect of low-temperature embrittlement, stepwise crushing, in-situ modification and plasma activation process realizes the high-value processing of heavy calcium carbonate, solves the problems of high energy consumption, uneven modification and low fine powder rate in traditional process; liquid nitrogen low-temperature spraying-50℃ to-30℃, generates thermal stress inside the stone, forms uniform micro-cracks, greatly reduces the subsequent crushing energy consumption, at the same time increases the active site on the particle surface, improves the reaction efficiency with the pretreatment composite additive; three-zone synergy: through the low-speed crushing zone to realize the gentle crushing of coarse particles and avoid over-crushing; the anchor reaction zone is high-speed shearing combined with atomized composite additives to promote the anchoring of the pretreatment composite additive on the new surface of the silane coupling agent; the solidification zone uniformly coats the pretreatment composite additive by mechanical force to form a stable modified layer. Double-stage turbo classification ensures that the high oil absorption value heavy calcium carbonate powder has a particle size of less than or equal to 2 μm and a particle size distribution of less than or equal to 3 μm, which meets the harsh requirements of high filling materials on fineness.

[0012] Preferably, the stone block in step S1 is microcrystalline marble with a purity of greater than or equal to 98% or limestone with a blue-white degree R457 of greater than or equal to 90%.

[0013] Preferably, the pretreatment composite additive is added in step S2 by spraying atomization, the compressed air pressure is 0.3-0.5 MPa, the flow rate is 0.8-1.2 L / min, and the droplet size is less than or equal to 20 μm.

[0014] Preferably, the pretreatment composite additive in step S2 comprises the following components by weight percentage of the pretreated stone block: PEG-6000 1.0-1.5%, KH-570 0.08-0.12%, nano cerium oxide 0.03-0.06%, and anhydrous ethanol 1.0-2.0%.

[0015] Through the above scheme, the pretreatment composite additive realizes the advantages of convenient performance adjustment, low energy consumption, small pollution, low cost, stable quality of heavy calcium powder and functionalization through the multi-mechanism synergy of chemical bonding, physical coating and nano enhancement. The long-chain PEG wraps the particles through physical adsorption, reduces the internal friction coefficient in the crushing process, inhibits the secondary agglomeration of particles, and at the same time improves the dispersibility of the powder in the molten resin; the silane coupling agent KH-570 is hydrolyzed by ethoxy to condense with the surface hydroxyl group of calcium carbonate to form a Si-O-Ca covalent bond, realizing chemical bonding modification and significantly improving the interfacial bonding force of the powder and the organic matrix; ethanol as a solvent promotes the uniform dispersion of KH-570 and avoids local agglomeration; under the action of high-energy mechanical force, part of the nano CeO2 is embedded in the defect site of calcium carbonate lattice to form a Ca-O-Ce interface structure, and at the same time the thermal stability of the powder is improved; the hydrophobic long chain of KH-570 and the hydrophilic segment of PEG form an amphoteric surface structure, so that the oil absorption value is significantly improved.

[0016] Preferably, the step S2 pretreatment composite additive further includes trace additives; the trace additives include the following components by weight percentage of the pretreated stone block raw material: KH-560 0.07-0.09 %, TMPTA 0.04-0.08 %, triethylene diamine 0.01-0.02 %, and TPO 0.01-0.02 %.

[0017] Through the above scheme, the pretreatment composite additive realizes performance transition by adding trace additives on the premise of the ternary main body of PEG-6000, KH-570 and nano CeO2. The addition of four kinds of small molecule oligomers has little impact on the original formula and is easy to produce directly on the existing production line. This minimalist scheme breaks the inert cognitive habit of "high anchoring rate = complex formula". The TPO photoinitiator triggers the rapid crosslinking of TMPTA and KH-560 to form a three-dimensional polymer network to wrap CaCO3 particles, thereby improving the oil absorption value; TPO produces active free radicals under light, which reacts with acrylate double bonds; triethylene diamine catalyzes the reaction of silane coupling agent and CaCO3 surface -OH, eliminating the competition of the two reactions and improving the catalytic efficiency.

[0018] Preferably, the step S2 curing zone is additionally provided with an outlet equipped with LED light strips, 365 nm, 10 W.

[0019] Through the above scheme, the curing zone is equipped with 365 nm LED light strips, which only needs to be irradiated for a short time. Its role is to trigger the photoinitiator TPO to produce free radicals instantaneously, rapidly crosslink TMPTA into an extremely thin net-like shell without changing the particle size of the powder; the residual heat continues to drive the silane-hydroxyl condensation of KH-560, KH-570 and CaCO3 to form "light nails + hot rivets" double anchor points, thereby improving the anchoring reaction rate.

[0020] Preferably, the step S2 pretreats the composite adjuvant: PEG-6000, KH-570, nano-CeO2 and trace adjuvant are dissolved in anhydrous ethanol in proportion, and ultrasonic dispersion is performed at 40 kHz for 10-15 min to ensure uniform dispersion of the nanoparticles.

[0021] Through the above scheme, the nano-sized coating is sprayed and atomized, the droplet particle size of the pretreated composite adjuvant after atomization is ≤20 μm, and a monomolecular layer is formed by high-speed collision to adsorb and anchor the KH-560 and KH-570 coupling agents on the particle surface, thereby improving the uniformity and realizing low consumption, high uniformity and high activity of the powder surface modification.

[0022] Preferably, the main classification wheel of the step S3 double-stage turbo classifier has a cutting particle size of D97=5 μm, and the auxiliary classification wheel has a cutting particle size of D97=2 μm.

[0023] Preferably, the step S3 real-time monitors the powder after classification; if the content of particles with a particle size less than 2 μm is <54%, the rotation speed of the auxiliary classification wheel is increased to 6500-7000 rpm and the amount of coarse powder returned is increased by 10-15%; and if D97>8 μm, the rotation speed of the main classification wheel is reduced to 3500-3800 rpm.

[0024] Preferably, the step S4 low-temperature plasma treatment has a power of 1.0-1.5 kW, argon and oxygen are mixed at a volume ratio of (8-9):1, and the treatment time is 3-5 min.

[0025] Through the above scheme, the low-temperature plasma treatment etches the surface of the particles with the mixed gas of argon and oxygen, thereby improving the oil absorption value while maintaining a low volatile content.

[0026] In a second aspect, the application provides a high-oil-absorption-value heavy calcium carbonate powder, which adopts the following technical scheme:

[0027] A high-oil-absorption-value heavy calcium carbonate powder is prepared by the preparation method.

[0028] Preferably, the high-oil-absorption-value heavy calcium carbonate powder has a particle size of ≤2 μm and an oil absorption value of ≥90 g / 100 g.

[0029] Through the above technical scheme, the high-oil-absorption-value heavy calcium carbonate powder prepared by the preparation method has the advantages of stable quality and functionalization, and has a surface interface effect close to that of light calcium carbonate and higher dispersibility than light calcium carbonate.

[0030] In a third aspect, the application provides an application of a high-oil-absorption-value heavy calcium carbonate powder, which adopts the following technical scheme:

[0031] The application of the high-oil-absorption-value heavy calcium carbonate powder in a polymer composite material.

[0032] Preferably, when the high oil absorption value heavy calcium carbonate powder is filled by 30% in the polyvinyl chloride artificial leather, the tensile strength is greater than or equal to 19.0 MPa, the plasticizer migration rate is less than 3.2%, and the surface is smooth and free of cracks.

[0033] By the technical scheme, the high oil absorption value heavy calcium carbonate powder is applied in the PVC product, and has good interface compatibility and high powder surface interface bonding force, and has good effect of replacing light calcium carbonate.

[0034] In summary, the application has the following beneficial effects:

[0035] 1. The preparation method of the high oil absorption value heavy calcium carbonate powder of the application realizes high value processing of heavy calcium carbonate through the cooperation of low temperature embrittlement, stepwise crushing, in-situ modification and plasma activation process, and solves the problems of high energy consumption, uneven modification and low fine powder rate in the traditional process.

[0036] 2. The preparation method of the high oil absorption value heavy calcium carbonate powder of the application sprays liquid nitrogen at a low temperature of-50℃ to-30℃, so that thermal stress is generated inside the stone and uniform microcracks are formed, the subsequent crushing energy consumption is greatly reduced, the active sites on the particle surface are increased, and the reaction efficiency with the pretreatment composite additive is improved; three-zone cooperation: the low-speed crushing zone realizes gentle crushing of coarse particles to avoid over-crushing; the anchor reaction zone realizes high-speed shearing combined with atomization spraying of the pretreatment composite additive to promote the anchoring of the pretreatment composite additive on the new surface of the silane coupling agent; the solidification zone uniformly coats the additive by mechanical force to form a stable modified layer; double-stage turbine classification ensures that the proportion of particles with a particle size of 2μm or less in the high oil absorption value heavy calcium carbonate powder is greater than or equal to 65%, meeting the stringent requirements of high filling materials on fineness.

[0037] 3. The high oil absorption value heavy calcium carbonate powder of the application has a particle size of 2μm or less and a particle proportion of greater than or equal to 65%, an oil absorption value of greater than or equal to 90g / 100g, and has the advantages of stable quality and functionalization, close to the surface interface effect of light calcium carbonate, and higher dispersibility than light calcium carbonate.

[0038] 4. The high oil absorption value heavy calcium carbonate powder of the application is applied in the PVC product, has good interface compatibility, and has high powder surface interface bonding force, and has good effect of replacing light calcium carbonate. DETAILED DESCRIPTION

[0039] The technical scheme of the application is further illustrated by specific embodiments, and the specific embodiments do not represent a limitation on the protection scope of the application; some non-essential modifications and adjustments made by others according to the concept of the application still belong to the protection scope of the application.

[0040] The test methods shown in the following examples are conventional methods, unless otherwise specified. The reagents and materials shown are commercially available products.

[0041] Ring roller mill: Longyan Yifeng Machinery Co., Ltd., Model 318 ring roller mill.

[0042] Polyethylene glycol-600 (abbreviation PEG-6000): Jiangsu Maoheng Chemical Co., Ltd., Item No. P042;

[0043] KH-570: Guangzhou Jianduan Chemical Technology Co., Ltd., Item No. 59C0017;

[0044] KH-560: Guangzhou Jianduan Chemical Technology Co., Ltd., Item No. 59C006;

[0045] Nano cerium oxide (abbreviation nano CeO2): Guangdong Hongcai Nanometer Material Technology Co., Ltd., Item No. HC-10003, particle size 40 nm, purity > 99.9%;

[0046] Trimethylolpropane triacrylate (abbreviation TMPTA): Shandong Xinhongyun Guang Chemical Co., Ltd., Model TMPTA;

[0047] Triethylenediamine (abbreviation DABCO): Zhengzhou Meifu Chemical Product Co., Ltd., Item No. 245;

[0048] 2,4,6-Trimethylbenzoyl diphenyl phosphine oxide (abbreviation TPO): Zhongshan Di Xin Chemical Co., Ltd., Item No. yaner79.

[0049] The application will be further described in detail in combination with examples and comparative examples. Example

[0050] Example 1

[0051] A method for preparing a high oil absorption value heavy calcium carbonate powder, adopts the following technical scheme:

[0052] S1 raw material pretreatment: The microcrystalline marble with a purity of ≥98% is treated by spraying liquid nitrogen at -40℃ for 8min, and the crushed material is broken to a particle size of ≤5mm to obtain pretreated stone block raw material;

[0053] S2: 100kg of pretreated stone block raw material is input into a ring roller mill, and the step-by-step treatment is completed in three zones: low-speed crushing: linear speed 13m / s, residence time 4s; anchor reaction: pretreated composite additives are added by spraying atomization, the compressed air pressure is 0.4MPa, the flow rate is 1.0L / min for atomization, the linear speed is 16m / s, and the residence time is 9s; solidification zone: linear speed 19m / s, residence time 13s;

[0054] S3: The classified powder is classified by a double-stage turbo classifier, the main classifier wheel cuts the particle size of D97=5 μm, the auxiliary classifier wheel cuts the particle size of D97=2 μm, and the classified powder is monitored in real time; if the particle size less than 2 μm accounts for less than 54%, the rotation speed of the auxiliary classifier wheel is increased to 6800 rpm and the amount of coarse powder returned is increased by 13%; if D97>8 μm, the rotation speed of the main classifier wheel is reduced to 3600 rpm; the particle size less than 2 μm accounts for more than or equal to 65% in the classified powder;

[0055] S4: The classified powder is treated by low-temperature plasma, the power is 1.0 kW, argon / oxygen is mixed at a volume ratio of 9:1, the treatment time is 5 min, and the high oil absorption value heavy calcium carbonate powder is obtained.

[0056] The pretreatment composite additive is prepared by dissolving 1.25 kg of PEG-6000, 0.1 kg of KH-570 and 0.046 kg of nano CeO2 in 1.8 kg of anhydrous ethanol, and ultrasonic dispersion is performed at 40 kHz for 10 min to ensure uniform dispersion of the nano particles.

[0057] Example 2

[0058] A method for preparing a high oil absorption value heavy calcium carbonate powder is adopted, and the technical scheme is as follows:

[0059] S1: The raw material pretreatment: the microcrystalline marble with a purity of more than or equal to 98% is treated by liquid nitrogen spraying at-30°C for 10 min, and the crushed material is crushed to a particle size of less than or equal to 5 mm to obtain pretreated stone block raw material;

[0060] S2: The 100 kg of pretreated stone block raw material is input into a ring roller mill, and the step-by-step treatment is completed in three zones: low-speed crushing: the linear speed is 12 m / s, and the residence time is 5 s; anchor reaction: the pretreatment composite additive is added by spray atomization, the compressed air pressure is 0.3 MPa, the flow rate is 0.8 L / min for atomization, the linear speed is 15 m / s, and the residence time is 10 s; solidification zone: the linear speed is 18 m / s, and the residence time is 15 s;

[0061] S3: The classified powder is classified by a double-stage turbo classifier, the main classifier wheel cuts the particle size of D97=5 μm, the auxiliary classifier wheel cuts the particle size of D97=2 μm, and the classified powder is monitored in real time; if the particle size less than 2 μm accounts for less than 54%, the rotation speed of the auxiliary classifier wheel is increased to 6800 rpm and the amount of coarse powder returned is increased by 13%; if D97>8 μm, the rotation speed of the main classifier wheel is reduced to 3600 rpm; the particle size less than 2 μm accounts for more than or equal to 65% in the classified powder;

[0062] S4: The classified powder is treated by low-temperature plasma, the power is 1.0 kW, argon / oxygen is mixed at a volume ratio of 9:1, the treatment time is 5 min, and the high oil absorption value heavy calcium carbonate powder is obtained.

[0063] The pretreatment composite aid: 1 kg of PEG-6000, 0.08 kg of KH-570, and 0.06 kg of nano CeO2 are dissolved in 1 kg of anhydrous ethanol, and ultrasonic dispersion is performed at 40 kHz for 15 min to ensure uniform dispersion of the nanoparticles.

[0064] Example 3

[0065] A preparation method of high oil absorption value heavy calcium carbonate powder, adopts the following technical scheme:

[0066] S1 raw material pretreatment: the microcrystalline marble with a purity of ≥98% is treated by liquid nitrogen spraying at-50°C for 5 min, and the crushed material is crushed to a particle size of ≤5 mm to obtain pretreated stone block raw material;

[0067] S2: 100 kg of pretreated stone block raw material is input into a ring roller mill, and the step-by-step treatment is completed in three zones: low-speed crushing: linear speed 15 m / s, residence time 3 s; anchor reaction: pretreatment composite aid is added by spray atomization, compressed air pressure 0.5 MPa, flow rate 1.2 L / min for atomization, linear speed 18 m / s, residence time 8 s; solidification zone: linear speed 20 m / s, residence time 10 s;

[0068] S3: classified by a double-stage turbine classifier, the main classification wheel cutting particle size is D97=5 μm, and the auxiliary classification wheel cutting particle size is D97=2 μm, and the powder after classification is monitored in real time; if the particle size is less than 2 μm and the particle content is <54%, the auxiliary classification wheel speed is increased to 7000 rpm and the coarse powder return amount is increased by 10%; if D97>8 μm, the main classification wheel speed is reduced to 3800 rpm; the particle content of the powder after classification is controlled to be ≥65% for particle size less than 2 μm;

[0069] S4: the powder after classification is treated by low-temperature plasma, the power is 1.5 kW, argon / oxygen is mixed at a volume ratio of 9:1, and the treatment time is 3 min to obtain high oil absorption value heavy calcium carbonate powder.

[0070] The pretreatment composite aid: 1.5 kg of PEG-6000, 0.12 kg of KH-570, and 0.03 kg of nano CeO2 are dissolved in 2 kg of anhydrous ethanol, and ultrasonic dispersion is performed at 40 kHz for 10 min to ensure uniform dispersion of the nanoparticles.

[0071] Example 4

[0072] The same as example 1, except that the stone block is a limestone with a blue-white degree R457≥90%.

[0073] Example 5

[0074] The same as example 1, except that the step S2 pretreatment composite aid further includes trace additives;

[0075] The pretreatment composite adjuvant: 1.25 kg PEG-6000, 0.1 kg KH-570, 0.046 kg nano CeO2 and 0.08 kg KH-560, 0.06 kg TMPTA, 0.015 kg triethylene diamine, 0.015 kg TPO were dissolved in 1.8 kg anhydrous ethanol, and ultrasonic dispersion was performed at 40 kHz for 10 min to ensure uniform dispersion of the nanoparticles.

[0076] The step S2 curing zone outlet is equipped with LED light bar, 365 nm, 10 W.

[0077] Example 6

[0078] The same as example 5, except that the step S2 pretreatment composite adjuvant also includes trace adjuvant;

[0079] The pretreatment composite adjuvant: 1.25 kg PEG-6000, 0.1 kg KH-570, 0.046 kg nano CeO2 and 0.07 kg KH-560, 0.04 kg TMPTA, 0.01 kg triethylene diamine, 0.01 kg TPO were dissolved in 1.8 kg anhydrous ethanol, and ultrasonic dispersion was performed at 40 kHz for 10 min to ensure uniform dispersion of the nanoparticles.

[0080] Example 7

[0081] The same as example 5, except that:

[0082] The step S2 pretreatment composite adjuvant also includes trace adjuvant; The pretreatment composite adjuvant: 1.25 kg PEG-6000, 0.1 kg KH-570, 0.046 kg nano CeO2 and 0.09 kg KH-560, 0.08 kg TMPTA, 0.02 kg triethylene diamine, 0.02 kg TPO were dissolved in 1.8 kg anhydrous ethanol, and ultrasonic dispersion was performed at 40 kHz for 10 min to ensure uniform dispersion of the nanoparticles.

[0083] Example 8

[0084] The same as example 5, except that the stone is limestone with blue light whiteness R457≥90%.

[0085] Comparative example

[0086] Comparative example 1

[0087] The same as example 1, the difference is that the step S1 raw material pretreatment is cancelled, liquid nitrogen pretreatment is used, normal temperature crushing is carried out using a cone crusher, the back-impact breaking rotor linear speed is 35-45 m / s, the discharge gap is adjusted to 3-5 mm, and crushing is carried out to ≤5 mm.

[0088] Comparative example 2

[0089] The same as example 1, the difference is that the step S2 anchor area, the pre-treatment composite additive is not added by spraying atomization, but is directly added and then stirred and mixed.

[0090] Comparative example 3

[0091] The same as example 1, the difference is that the step S4 plasma treatment is cancelled.

[0092] Comparative example 4

[0093] The same as example 1, the difference is that the step S2 pre-treatment composite additive, KH-570 is replaced by stearic acid, the pre-treatment composite additive: 1.25 kg of PEG-6000, 0.1 kg of stearic acid, and 0.046 kg of nano CeO2 are dissolved in 1.8 kg of absolute ethanol, and ultrasonic dispersion is carried out at 40 kHz for 10 min to ensure uniform dispersion of the nano particles.

[0094] Comparative example 5

[0095] The same as example 1, the difference is that the step S2 pre-treatment composite additive does not add nano CeO2; the pre-treatment composite additive: 1.25 kg of PEG-6000, 0.1 kg of KH-570 are dissolved in 1.8 kg of absolute ethanol, and ultrasonic dispersion is carried out at 40 kHz for 10 min to ensure uniform dispersion of the nano particles.

[0096] Comparative example 6

[0097] The same as example 1, the difference is that the step S2 pre-treatment composite additive does not add KH-570; the pre-treatment composite additive: 1.25 kg of PEG-6000, 0.046 kg of nano CeO2 are dissolved in 1.8 kg of absolute ethanol, and ultrasonic dispersion is carried out at 40 kHz for 10 min to ensure uniform dispersion of the nano particles.

[0098] Comparative example 7

[0099] The same as example 5, except that the step S2 pretreatment composite auxiliary removes KH-560 and TMPTA, and the other components are retained; the pretreatment composite auxiliary: 1.25 kg of PEG-6000, 0.1 kg of KH-570, 0.046 kg of nano CeO2, 0.015 kg of triethylene diamine, and 0.015 kg of TPO are dissolved in 1.8 kg of anhydrous ethanol, and ultrasonic dispersion is performed at 40 kHz for 10 min to ensure uniform dispersion of the nanoparticles.

[0100] Comparative example 8

[0101] The same as example 5, except that the step S2 pretreatment composite auxiliary removes TPO, and the other components are retained; the pretreatment composite auxiliary: 1.25 kg of PEG-6000, 0.1 kg of KH-570, 0.046 kg of nano CeO2, 0.08 kg of KH-560, 0.06 kg of TMPTA, and 0.015 kg of triethylene diamine are dissolved in 1.8 kg of anhydrous ethanol, and ultrasonic dispersion is performed at 40 kHz for 10 min to ensure uniform dispersion of the nanoparticles.

[0102] Comparative example 9

[0103] The same as example 5, except that the step S2 pretreatment composite auxiliary removes DABCO, and the other components are retained; the pretreatment composite auxiliary: 1.25 kg of PEG-6000, 0.1 kg of KH-570, 0.046 kg of nano CeO2, 0.08 kg of KH-560, 0.06 kg of TMPTA, and 0.015 kg of TPO are dissolved in 1.8 kg of anhydrous ethanol, and ultrasonic dispersion is performed at 40 kHz for 10 min to ensure uniform dispersion of the nanoparticles.

[0104] Comparative example 10

[0105] The same as example 5, except that the step S2 uses traditional thermal curing instead of LED irradiation, and the thermal curing is 80°C hot air for 10 s.

[0106] Performance detection test

[0107] 1. Oil absorption value: determined according to GB / T 19281-2014 by linseed oil titration method;

[0108] 2. Particle size distribution: a Malvern Mastersizer 3000 laser particle size instrument is used to detect the content of particles with a particle size of less than 2 μm in the high oil absorption value heavy calcium carbonate powder;

[0109] 3. Application performance: The high oil absorption value heavy calcium carbonate powder prepared by using Examples 1-8 and Comparative Examples 1-10 is applied in polyvinyl chloride (PVC) artificial leather, and the filling is 30%; the tensile strength and plasticizer migration rate are detected.

[0110] Specific application method: 100 kg of PVC resin, 30 kg of heavy calcium carbonate powder, 45 kg of DOP plasticizer, etc. are added into a high-speed mixer, mixed at 500 rpm and 80°C for 5 min to be uniform, the temperature of the internal mixer is 160°C, the rotor speed is 30 rpm, the plasticizing time is 8-10 min, the four-roll calender, the roller temperature is 170°C, 12 m / min, the thickness is controlled to be 0.8 mm, and after cooling, it is wound up.

[0111] Tensile strength detection method: referring to GB / T 1040.3-2006, determination of tensile properties of plastics, the sample is cut into 63 mm long and 3.2 mm wide, and is placed at 23±2°C and 50±5%RH for 24 h, a tensile testing machine is used, the tensile speed is 50 mm / min, and the test is started until breaking; the tensile strength (MPa) = maximum load / (width x thickness).

[0112] Plasticizer migration rate detection method: referring to QB / T 2729-2005, plasticizer extraction test, the sample is cut into a 20 mm x 20 mm square, the sample is clamped between two filter papers, a pressure of 10 kPa is applied, and it is placed in a 70°C oven for 7 days, the filter paper is taken out, weighed after cooling, and the migration rate (%) = (weight after migration test-initial weight of filter paper) / initial weight of sample x 100%.

[0113] The high oil absorption value heavy calcium carbonate powder prepared by Examples 1-8 and Comparative Examples 1-10 is subjected to oil absorption value, content of particles with particle size less than 2 μm, tensile strength and plasticizer migration rate determination test results as shown in Table 1.

[0114]

[0115] As shown in Table 1, the oil absorption value of Examples 1-4 is in the range of 96-98 g / 100 g, the content of particles with particle size less than 2 μm is all ≥65%, and the detection result data of each example fluctuates very little, indicating that the process parameter fault tolerance is high and is suitable for industrialization.

[0116] The oil absorption value of Examples 5-8 is in the range of 100-104 g / 100 g, the content of 2 μm particles is all ≥65%, the tensile strength is 22.4-22.7 MPa, and the plasticizer migration rate is 2.7-2.9%, and the comprehensive performance is better than that of Examples 1-4.

[0117] The oil absorption value of the powder prepared by normal temperature crushing in Comparative Example 1 is reduced to only 68 g / 100 g, and the content of particles with a particle size less than 2 μm is 52%, which does not meet the product requirements, and the energy consumption of later crushing is increased due to the lack of micro-cracks.

[0118] In the preparation of Comparative Example 2, the pre-treatment composite additive is mixed by stirring, resulting in uneven distribution of the pre-treatment composite additive, and the oil absorption value is 85 g / 100 g, and when applied to polyvinyl chloride artificial leather, it leads to easy separation of DOP, and the plasticizer migration rate is increased to 5.2%; it is proved that spraying and atomization are very necessary for uniform modification;

[0119] In the preparation of Comparative Example 3, no plasma treatment is performed, although the particle size meets the standard, but the surface polarity group is not activated, and the oil absorption value is reduced to 80 g / 100 g.

[0120] In the preparation of Comparative Example 4, the KH-570 of the pre-treatment composite additive is replaced by stearic acid, which only has physical adsorption function and cannot form Si-O-Ca covalent bond, resulting in weak powder-PVC interfacial bonding force and a decrease in tensile strength to 15 MPa.

[0121] In the preparation of Comparative Example 5, no nano-CeO2 is added to the pre-treatment composite additive, resulting in a decrease in oil absorption value of 86 g / 100 g, the embedding of nano-CeO2 can increase the surface defect pores of particles, and the lack of nano-CeO2 leads to a decrease in adsorption sites, and the absence of the grinding aid effect of CeO2 leads to a deterioration of particle size control, and the content of particles with a particle size less than 2 μm is reduced to 58%.

[0122] In the preparation of Comparative Example 6, no KH-570 is added, resulting in a sharp drop in oil absorption value to 72 g / 100 g, the hydrophobic long chain (-CH=CH2) of KH-570 is the main contributor to the oil absorption value, and the lack of KH-570 leads to a sharp drop in the adsorption capacity of polar oil, and the interface bonding is invalid, resulting in a decrease in tensile strength of 14.2 MPa, and PEG can only be physically adsorbed and cannot form Si-O-Ca covalent bond like KH-570; the plasticizer migration rate is doubled, and DOP is easily separated due to the weak interfacial bonding force.

[0123] Comparative Example 7 is the same as Example 5, except that in the preparation process, the pre-treatment composite additive removes KH-560 and TMPTA, and the oil absorption value is only 92 g / 100 g, which proves that the cross-linked network structure of KH-560 and TMPTA is the key to improving the oil absorption value.

[0124] Comparative Example 8 is the same as Example 5, except that in the preparation process, the pre-treatment composite additive removes TPO; the plasticizer migration rate is relatively high at 3.2%, which indicates that incomplete photoinitiation of TPO removal will lead to interface bonding defects.

[0125] Comparative Example 9 is the same as Example 5, except that the pretreatment composite auxiliary removes DABCO in the preparation process, and the tensile strength is low, indicating that the epoxy-acrylic dual catalysis can enhance the interfacial stress transfer of PVC and CaCO3.

[0126] Comparative Example 10 is the same as Example 5, except that the step S2 uses traditional heat curing instead of LED irradiation, which has higher energy consumption and higher plasticizer migration rate.

[0127] From the above test results, the application prepares a high oil absorption value heavy calcium carbonate powder preparation method, through the synergy of low temperature embrittlement, stepwise crushing, in-situ modification and plasma activation process, realizes the high value processing of heavy calcium carbonate, solves the problems of high energy consumption, uneven modification and low fine powder rate in the traditional process. The high oil absorption value heavy calcium carbonate powder has a particle size of 2 μm or less, an oil absorption value of ≥90 g / 100 g, and the advantages of stable quality and functionalization, which is close to the surface and interface effect of light calcium carbonate, and has higher dispersibility than light calcium carbonate. When applied in PVC products, it not only has good interfacial compatibility, but also has high powder surface and interface bonding force, and has good replacement of light calcium carbonate

[0128] The specific embodiments are only an explanation of the application, and are not a limitation of the application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the application and are protected by the patent law.

Claims

1. A method for producing a high oil absorption value heavy calcium carbonate powder, characterized by, The technical scheme comprises the following steps: S1: raw material pretreatment: the stone is crushed to a particle size of ≤5 mm; the crushed material is treated by spraying liquid nitrogen at -50 to -30 ℃ for 5-10 min to induce micro-crack generation, thereby obtaining pretreated stone raw material; S2: the pretreated stone raw material is input into a ring roller mill, and the material is processed in three zones: low-speed crushing zone: linear velocity of 12-15 m / s, residence time of 3-5 s; anchor reaction zone: pretreated composite additives are added, linear velocity of 15-18 m / s, residence time of 8-10 s; solidification zone: linear velocity of 18-20 m / s, residence time of 10-15 s; S3: the material is classified by a double-stage turbo classifier, and the content of particles with a particle size of less than 2 μm in the classified powder is controlled to be ≥65%; S4: the classified powder is treated by low-temperature plasma, thereby obtaining high oil absorption value heavy calcium carbonate powder; In step S2, the pretreated composite additives are added by spraying atomization, the compressed air pressure is 0.3-0.5 MPa, the pretreated additive solution flow rate is 0.8-1.2 L / min, and the mist droplets with a particle size of ≤20 μm are formed; In step S2, the pretreated composite additives comprise the following components by weight percentage of the pretreated stone raw material: PEG-6000 1.0-1.5%, KH-570 0.08-0.12%, nano cerium oxide 0.03-0.06%, and anhydrous ethanol 1.0-2.0%; In step S2, the pretreated composite additives further comprise trace additives; the trace additives comprise the following components by weight percentage of the pretreated stone raw material: KH-560 0.07-0.09%, TMPTA 0.04-0.08%, triethylenediamine 0.01-0.02%, and TPO 0.01-0.02%. In step S1, the stone is microcrystalline marble with a purity of ≥98% or limestone with a blue-white degree R457 of ≥90%.

2. The method for preparing high oil absorption value heavy calcium carbonate powder according to claim 1, characterized in that, In step S3, the main classification wheel of the double-stage turbo classifier has a cutting particle size of D97=5 μm, and the auxiliary classification wheel has a cutting particle size of D97=2 μm.

3. The method for preparing high oil absorption value heavy calcium carbonate powder according to claim 1, characterized in that, In step S3, the classified powder is monitored in real time; if the content of particles with a particle size of less than 2 μm is <54%, the rotation speed of the auxiliary classification wheel is increased to 6500-7000 rpm, and the amount of coarse powder returned is increased by 10-15%; if D97>8 μm, the rotation speed of the main classification wheel is reduced to 3500-3800 rpm.

4. The method for preparing high oil absorption value heavy calcium carbonate powder according to claim 1, characterized in that, In step S4, the low-temperature plasma treatment is performed at a power of 1.0-1.5 kW, argon and oxygen are mixed at a volume ratio of (8-9):1, and the treatment time is 3-5 min.

5. The method for preparing high oil absorption value heavy calcium carbonate powder according to claim 1, characterized in that, The high oil absorption value heavy calcium carbonate powder is prepared by the preparation method of any one of claims 1-5.

6. A high oil absorption value ground calcium carbonate powder, characterized in that:

7. Application of the high oil absorption value heavy calcium carbonate powder of claim 6 in polyvinyl chloride materials. ​

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