阅读说明：本技术 一种用于环保纸基高阻隔包装材料的滑石粉的制备方法 (Preparation method of talcum powder for environment-friendly paper-based high-barrier packaging material ) 是由 杜艳芬 刘金刚 夏菲 于 2020-11-24 设计创作，主要内容包括：本发明属于制浆造纸领域,尤其涉及一种用于环保纸基高阻隔包装材料的滑石粉的制备方法。将粗磨后的滑石粉与助磨分散剂、润湿剂、抑泡剂等在研磨机中进行研磨、得到片状滑石粉微粒,其径厚比达到40以上、甚至可达110,平均粒径小于4μm、中位径(D50)小于2μm、小于2μm的粒子数量大于50％,在水中具有良好的润湿、分散性能,固含量高、稳定性好、泡沫少。该产品与可降解高分子分散液混合、施涂于纸基上,涂布量为20g/m~2左右时；或者该产品与可降解高分子分散液混合、施涂于纸基上,涂布量为7g/m~2左右,表面再施涂纯可降解高分子分散液5g/m~2左右时,可达到纯可降解高分子分散液涂布量16g/m~2左右的阻隔效果,显著提高纸基的阻水、阻油性能并降低生产成本。(The invention belongs to the field of pulping and papermaking, and particularly relates to a preparation method of talcum powder for an environment-friendly paper-based high-barrier packaging material. The coarse ground talcum powder, grinding aid dispersant, wetting agent, foam inhibitor and the like are ground in a grinding machine to obtain flaky talcum powder particles, the diameter-thickness ratio of the flaky talcum powder particles reaches more than 40 and even 110, the number of particles with the average particle size of less than 4 mu m, the median diameter (D50) of less than 2 mu m and less than 2 mu m is more than 50 percent, and the flaky talcum powder particles have good wetting and dispersing properties in water, high solid content, good stability and less foam. The product is mixed with degradable high molecular dispersion,Applying on paper base with coating weight of 20g/m 2 On the left and right sides; or the product is mixed with degradable high molecular dispersion liquid and applied on a paper base, and the coating weight is 7g/m 2 On the left and right sides, the surface is coated with 5g/m of pure degradable macromolecular dispersion liquid 2 About the same time, the coating weight of the pure degradable polymer dispersion liquid can reach 16g/m 2 The water and oil resistance of the paper base is obviously improved and the production cost is reduced due to the left and right blocking effects.)

1. A preparation method of talcum powder for an environment-friendly paper-based high-barrier packaging material is characterized by comprising the following steps of:

1) putting the grinding beads into a grinding machine, wherein the filling rate of the grinding beads is 30-70%;

2) adding the coarsely ground talcum powder into a tank body, wherein the mass ratio of grinding beads to the talcum powder (namely the ball-material ratio) is 5-30: 1, adding clear water to ensure that the solid content of the talcum powder is 30-95%, and adding a proper amount of auxiliary agent;

3) starting grinding, controlling the rotating speed of a grinding machine to be 500-1200 rpm, and grinding time to be 1-8 h, and supplementing the auxiliary agent for 1-2 times in the grinding process;

4) filtering the ground talcum powder dispersion liquid, or drying and crushing to obtain the flaky talcum powder pigment with high aspect ratio.

2. The preparation method of the talcum powder for the environment-friendly paper-based high-barrier packaging material as claimed in claim 1, wherein the preparation method comprises the following steps: the used coarse ground talc powder is 325-1500 meshes, and the granularity is about 10-45 mu m.

3. The preparation method of the talcum powder for the environment-friendly paper-based high-barrier packaging material as claimed in claim 1, wherein the preparation method comprises the following steps: the grinding beads are made of agate, high-strength wear-resistant rubber, glass or ceramic and the like, and the diameter of the grinding beads is 5-30 mm.

4. The preparation method of the talcum powder for the environment-friendly paper-based high-barrier packaging material as claimed in claim 1, wherein the preparation method comprises the following steps: the added auxiliary agents are grinding aid dispersing agents, wetting agents, foam inhibitors and the like.

5. The preparation method of the talcum powder for the environment-friendly paper-based high-barrier packaging material as claimed in claims 1 and 4, wherein the preparation method comprises the following steps: the grinding-aid dispersing agent is polyacrylate dispersing agent, polycarboxylate dispersing agent and the like, and is added twice, wherein the adding amount is 0.5-5% and 0.01-3% respectively.

6. The preparation method of the talcum powder for the environment-friendly paper-based high-barrier material as claimed in claims 1 and 4, wherein the preparation method comprises the following steps: the wetting agent is dioctyl sodium succinate, polyhydric alcohol polyoxyethylene ether and the like, and the dosage of the wetting agent is 0.1-1%.

7. The preparation method of the talcum powder for the environment-friendly paper-based high-barrier packaging material as claimed in claims 1 and 4, wherein the preparation method comprises the following steps: the foam inhibitor is organic silicon foam inhibitor, wax emulsion and the like, and the dosage is 0.01-0.5%.

8. The preparation method of the talcum powder for the environment-friendly paper-based high-barrier packaging material as claimed in claim 1, wherein the preparation method comprises the following steps: the product particles are monolithic, have smaller particle size and higher form ratio, the average particle size of the product is smaller than 4 mu m, the median diameter (D50) is smaller than 2 mu m by adopting a sedimentation method, and the diameter-thickness ratio of the particles is 40-110 by observing and analyzing through a scanning electron microscope.

9. The preparation method of the talcum powder for the environment-friendly paper-based high-barrier packaging material as claimed in claims 1 and 8, wherein the preparation method comprises the following steps: the product is mixed with degradable high molecular dispersion liquid and applied on a paper base, and the coating weight is 20g/m²About the same time, the coating weight of the pure degradable polymer dispersion liquid can reach 16g/m²Barrier effect around, i.e. a Cobb value (2min) of less than 1g/m²And the oil resistance grade of Kit is 12 grade, and the oil resistance is qualified.

10. The preparation method of the talcum powder for the environment-friendly paper-based high-barrier packaging material as claimed in claims 1 and 8, wherein the preparation method comprises the following steps: the product is mixed with degradable high molecular dispersion liquid and applied on a paper base, and the coating weight is 7g/m²On the left and right sides, the surface is coated with 5g/m of pure degradable macromolecular dispersion liquid²About 16g/m of coating weight of the pure degradable polymer dispersion liquid can be achieved²Barrier effect around, i.e. a Cobb value (2min) of less than 1g/m²And the oil resistance grade of Kit is 12 grade, and the oil resistance is qualified.

Technical Field

The invention belongs to the field of pulping and papermaking, and particularly relates to a preparation method of flaky high-form-ratio talc powder for an environment-friendly paper-based high-barrier packaging material.

Background

With the advance of plastic-limiting reams, development and application of environment-friendly degradable paper-based high-barrier packaging materials are receiving more and more attention. The traditional paper-based high-barrier packaging material takes paper or paperboard as a base material, and a high molecular polymer such as Polyethylene (PE) is coated on the surface of the base material to achieve the functions of resisting water, oil, oxygen or water vapor permeation; these composite high barrier materials are difficult to recycle and biodegrade due to the difficulty in peeling and degrading the plastic film. The environment-friendly degradable material, such as natural high molecular polymer, such as nano cellulose, starch, chitosan and the like, or synthetic high molecular polymer, such as polyacrylic emulsion, polyvinyl alcohol and the like, is adopted to carry out surface treatment on paper or paperboard, so that the barrier property of the material is improved, and the material replaces a high-barrier packaging material of plastic coating film, and becomes a new trend for the development of the paper packaging field.

The degradable high molecular polymer is applied on the surface of paper or paperboard by a conventional coating mode (such as a scraper, a bar, curtain coating and the like) to form a continuous, compact and hydrophobic film layer for blocking liquid and gas from permeating through the material. To obtain a dense film layer, good barrier effect, the coating application level generally needs to exceed 15g/m²(ii) a The price of these degradable high polymer materials is usually higher than that of plastic films such as PE, which leads to high cost of the degradable barrier coating and limits the popularization and use of the environment-friendly degradable paper-based barrier package. The inorganic mineral pigment with flake shape and high aspect ratio (namely diameter-thickness ratio) and the high molecular polymer are used for preparing the coating and coating, so that the barrier property of the material can be effectively improved, and the production cost can be obviously reduced.

Talc is a magnesium silicate with good laminarization, high whiteness, stable chemical property, lubricity, thermal stability, adsorptivity, suspension property and the like, is widely applied to industries such as papermaking, plastics, coatings, paints, ceramics, rubber, waterproof materials, medicines, cosmetics and the like, plays roles of filling, increasing and reducing cost, can enhance the processing performance, mechanical strength, thermodynamic performance and the like of products, and is an important inorganic mineral raw material. The talcum powder is the most traditional mineral powder raw material in the paper making industry in China, and the highest consumption reaches 140 ten thousand t/year in the late 90 th of the 20 th century. Domestic papermaking talcum powder is mainly used for filling, and a small amount of the talcum powder is used for controlling stickies and coating. Talc powder can be used for light coated paper and coated offset printing paper, but is not much applied as a coating pigment in domestic paper mills because the talcum powder is hydrophobic and oleophilic, is difficult to disperse, has lower solid content of dispersion liquid, can generate more foams and has poorer suspension stability.

At present, the talc powder in China is mainly produced by dry processing, namely, selecting smooth stone blocks, coarse crushing, drying, middle crushing, and then carrying out fine grinding and superfine grinding. The processing equipment such as a Raymond mill, a mechanical impact crusher, an air flow mill and the like is used for producing the talcum powder with 200 meshes, 325 meshes and 500-1250 meshes; the fineness of the produced superfine-ground talcum powder can reach 500-5000 meshes by using a superfine-ground talcum powder pulverizer. Most of the talcum powder on the market is simply purified and refined, the obtained talcum powder is also in a granular shape formed by stacking a plurality of layers, and although the small part of the talcum powder is stripped, the stripping effect is not ideal, and the defects of low content of single-layer flaky talcum powder and damaged laminated structure exist.

Patent 201611211666.7 discloses a method for preparing low viscosity high dispersion type paper-making talcum powder, mixing fluorite and hectorite, ball milling, stirring and mixing with deionized water, stirring and mixing with chitosan and acetic acid solution, and performing ultrasonic dispersion to obtain modified dispersion liquid; mixing with talcum powder dispersion, keeping the temperature, standing for aging, filtering, collecting filtrate, washing with deionized water, drying, cooling to obtain dry modified talcum powder, preheating, heating, calcining, cooling, and ball-milling calcined substance to obtain the low-viscosity high-dispersion papermaking talcum powder.

Patent 201810461943.2 discloses a method for preparing talc powder specially used for coating pigment, which comprises heating, pressurizing, stirring and reacting talc powder, phospholipid and water, filtering, washing, drying and roasting to obtain pretreated talc powder; then ball-milling and mixing the pretreated talcum powder and an inorganic strong acid solution to prepare a ball grinding material, and filtering, washing and drying the ball grinding material to obtain ball-milled modified talcum powder; ultrasonically dispersing the ball-milling modified talcum powder, polyvinylpyrrolidone and water to obtain a dispersion liquid, dropwise adding tetraethoxysilane into the dispersion liquid under the stirring state, continuously stirring for reaction after the tetraethoxysilane is dropwise added, discharging, filtering, washing and drying to obtain coated modified talcum powder; and calcining the obtained coated modified talcum powder, cooling along with the furnace, and discharging to obtain the special talcum powder for coating the pigment.

Patent 201710949109.3 discloses a method for preparing monolithic talc powder by adding talc powder and a coupling agent to a high speed mixer to obtain a premix; dispersing and mixing the talcum powder and a foaming agent, adding the mixture into a rotary homogenizer, and gradually stripping the talcum powder under the shearing action of a rotary blade to obtain a single-sheet talcum powder primary product; after washing with water, acetone and drying, monolithic talc is obtained. However, none of these inventions mention the morphological indications that the product achieves, nor does it mention whether it can be used as a coating for paper-based high barrier packaging materials to improve the barrier properties of the material.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a preparation method of flaky high-aspect-ratio talc powder. The talcum powder particles produced by the method are monolithic, have the diameter-thickness ratio of more than 40 and even up to 110, have the average particle diameter of less than 4 mu m, the median diameter (D50) of less than 2 mu m and the particle number of less than 2 mu m of more than 50 percent, have good wetting and dispersing properties in water, have high solid content, good stability and less foam, can be prepared into a coating with environment-friendly and degradable high polymer dispersion liquid, and can be applied to paper or paperboard, thereby obviously improving the water and oil resistance of the paper base and reducing the production cost.

The technical scheme adopted by the invention is as follows:

(1) putting the grinding beads into a grinding machine, wherein the filling rate of the grinding beads is 30-70%;

(2) adding the coarsely ground talcum powder into a tank body, wherein the mass ratio of grinding beads to the talcum powder (namely the ball-material ratio) is 5-30: 1, adding clear water to ensure that the solid content of the talcum powder is 30-95%, and adding a proper amount of auxiliary agent;

(3) starting grinding, controlling the rotating speed of a grinding machine to be 500-1200 rpm, and grinding time to be 1-8 h, and supplementing the auxiliary agent for 1-2 times in the grinding process;

(4) filtering the ground talcum powder dispersion liquid, or drying and crushing to obtain the flaky talcum powder pigment with high aspect ratio.

The grinding beads in the step (1) can be made of agate, high-strength wear-resistant rubber, glass or ceramic and the like, and the diameter of the grinding beads is 5-30 mm; the adopted grinder is a planetary ball mill or a sand mill, and the material of the tank body is polytetrafluoroethylene, corundum or ceramic and the like;

in the step (2), the talcum powder is 325-1500 meshes and has the granularity of 10-45 mu m; the added auxiliary agents are grinding aid dispersing agents, wetting agents, foam inhibitors and the like;

the grinding-aid dispersing agent in the step (2) is a polyacrylate dispersing agent, a polycarboxylate dispersing agent and the like, and the using amount is 0.5-5%; the wetting agent is dioctyl sodium succinate, polyhydric alcohol polyoxyethylene ether and the like, and the using amount is 0.1-1%; the foam inhibitor is organic silicon foam inhibitor, wax emulsion and the like, and the dosage is 0.01-0.5%;

the rotating speed of the grinder in the step (3) can be kept unchanged, and the high speed can be carried out at first and then the medium-high speed is carried out; the supplementary assistant is a grinding-aid dispersant, the type of the supplementary assistant is polyacrylate, polycarboxylate or the like, and the using amount of the supplementary assistant is 0.01-3%;

filtering the ground talcum powder dispersion liquid (for example, the solid content is below 70%) in the step (4) by using a 100-325-mesh screen to obtain flaky talcum powder pigment dispersion liquid with high aspect ratio, and directly coating the flaky talcum powder pigment dispersion liquid with a coating prepared from degradable high polymer dispersion liquid and the like;

drying and crushing the ground talcum powder (with solid content of about 90%) in the step (4) to obtain flaky talcum powder pigment with high aspect ratio, directly dispersing the flaky talcum powder pigment in water to form dispersion liquid, and coating the dispersion liquid with a coating prepared from degradable high-molecular dispersion liquid and the like;

the drying and pulverizing of the talc powder in the step (4) may be carried out by using conventional equipment such as a vacuum dryer, a pneumatic pulverizer, a grinder, etc.

The talcum powder particles produced by the method are monolithic and have smaller particle size and higher form ratio: detecting that the average particle size is less than 4 microns, the median diameter (D50) is less than 2 microns by a sedimentation method, and analyzing the particle size-thickness ratio of 40-110 by scanning electron microscope observation; the dispersion has good dispersibility in water, and the solid content of the dispersion is high and bubbles are few; the water-resistant oil-resistant paper base material can be prepared into uniform and stable coating with environment-friendly degradable high molecular polymers such as polyacrylic emulsion, polyvinyl alcohol, modified starch and the like, and the coating is coated on the surface of paper or paperboard, so that the water resistance and oil resistance of the paper base material are obviously improved, and the production cost is reduced.

Detailed Description

The above and further features and advantages of the invention are explained in more detail below with reference to examples and test data, without being limited thereto.

Example 1:

weighing 300g of agate grinding beads, and putting the agate grinding beads into a grinding tank of a planetary ball mill, wherein the agate grinding beads with the diameter of 25-30 mm account for 55% of the total mass of the grinding beads, and the agate grinding beads with the diameter of 10-15 mm account for 45% of the total mass of the grinding beads; weighing 60g of 325-mesh talcum powder, putting the talcum powder into a grinding tank, adding 60g of water, adding 0.29g of dioctyl sodium succinate wetting agent, 1.25g of acrylate grinding dispersant and 0.02g of foam inhibitor; and (3) starting a grinding machine, controlling the rotating speed to be 800rpm, adding 0.25g of grinding dispersant after grinding for 4 hours, stopping after continuing grinding for 2 hours, and filtering by adopting a 100-mesh screen to obtain the talcum powder pigment dispersion liquid. Taking materials for detection, wherein the average particle size of the talcum powder is 2.995 micrometers, the median diameter is 1.994 micrometers, and the number of particles smaller than 2 micrometers is 50.6%; the talcum powder is in a sheet shape and the diameter-thickness ratio reaches 42 under the observation of a scanning electron microscope.

Example 2:

weighing 600g of ceramic grinding beads, and putting the ceramic grinding beads into a grinding tank of a planetary ball mill, wherein the ceramic grinding beads with the diameters of 20-25 mm account for 50% of the total mass of the grinding beads, and the ceramic grinding beads with the diameters of 5-10 mm account for 50% of the total mass of the grinding beads; weighing 60g of 325-mesh talcum powder, putting the talcum powder into a grinding tank, adding 40g of water, adding 0.50g of wetting agent, 55g of grinding dispersant and 0.015g of foam inhibitor; and (3) starting a grinding machine, controlling the rotating speed to be 1000rpm, adding 0.93g of grinding dispersant after grinding for 2h, stopping grinding after continuing grinding for 2h, and filtering by adopting a 100-mesh screen to obtain the talcum powder pigment dispersion liquid. Taking materials for detection, wherein the average particle size of the talcum powder is 2.704 mu m, the median diameter is 1.611 mu m, and the number of particles smaller than 2 mu m is 57.7%; the talcum powder is in a sheet shape and the diameter-thickness ratio reaches 49 under the observation of a scanning electron microscope.

Example 3:

weighing 600g of agate grinding beads with the diameter of 10-20 mm, putting the agate grinding beads into a grinding tank of a planetary ball mill, weighing 30g of 1250-mesh talcum powder, putting the talcum powder into the grinding tank, adding 30g of water, and adding 0.19g of wetting agent, 0.47g of grinding dispersant and 0.007g of foam inhibitor; and (3) starting a grinding machine, controlling the rotating speed to be 1000rpm, adding 0.11g of grinding dispersant after grinding for 0.5h, stopping grinding after continuing grinding for 0.5h, and filtering by adopting a 325-mesh screen to obtain the talcum powder pigment dispersion liquid. Taking materials for detection, wherein the average particle diameter of the talcum powder is 1.461 μm, the median diameter is 0.958 μm, and the number of particles smaller than 2 μm is 72.9%; the talcum powder is in a sheet shape and the diameter-thickness ratio reaches 110 under the observation of a scanning electron microscope.

And mixing the ground talcum powder dispersion liquid with polyacrylic acid emulsion to prepare a coating, coating the coating on base paper of the packaging paper by using a scraping rod, drying at 105 ℃, and detecting the Cobb water absorption value, the Kit oil resistance grade (Tappi UM 557) and the oil and grease resistance degree (GB36392-2018) of the paper according to related standards. The Cobb Water absorption value (2min) of the base paper is 24.7g/m²The Kit oil resistance grade is 0 grade, and the oil resistance degree is unqualified; the coating is applied by degradable polyacrylic acid emulsion, and the coating weight is 16.5g/m²When the water absorption value of Cobb is 0.29g/m (2min)²The oil resistance grade of Kit is 12 grade, and the oil resistance is qualified; the talcum powder and polyacrylic emulsion mixed coating (the mass ratio is 50: 50) are applied in a single layer, and the coating weight is 21.0g/m²When the water absorption value of Cobb is 0.29g/m (2min)²The oil resistance grade of Kit is 12 grade, and the oil resistance is qualified; the talcum powder and polyacrylic emulsion mixed coating (mass ratio is 75: 25) are pre-coated on the base paper, and the coating weight is 6.4g/m²Then pure polyacrylic acid emulsion is coated on the surface, and the coating weight is 5.8g/m²The Cobb water absorption value (2min) is 0.16g/m²And the oil resistance grade of Kit is 12 grade, and the oil resistance is qualified.

Example 4:

weighing 600g of glass grinding beads with the diameter of 10-20 mm, putting the glass grinding beads into a grinding tank of a planetary ball mill, weighing 50g of 1250-mesh talcum powder, putting the talcum powder into the grinding tank, adding 60g of water, adding 0.3g of wetting agent, 1.9g of grinding dispersant and 0.015g of foam inhibitor; and (3) starting a grinding machine, controlling the rotating speed to be 1100rpm, adding 0.1g of grinding dispersant after grinding for 2h, stopping after continuing grinding for 2h, and filtering by adopting a 325-mesh screen to obtain the talcum powder pigment dispersion liquid. Taking materials for detection, wherein the average particle diameter of the talcum powder is 1.033 mu m, the median diameter is 0.675 mu m, and the number of particles smaller than 2 mu m is 90.1%; the talcum powder is in a sheet shape and the diameter-thickness ratio reaches 88 under the observation of a scanning electron microscope.

And mixing the ground talcum powder dispersion liquid with polyacrylic acid emulsion to prepare a coating, coating the coating on laminating base paper by using a scraping rod, drying at 105 ℃, and detecting the Cobb water absorption value, the Kit oil resistance grade (Tappi UM 557) and the oil and grease resistance degree (GB36392-2018) of the paper according to related standards. The Cobb Water absorption value (2min) of the base paper was 26.1g/m²The Kit oil resistance grade is 0 grade, and the oil resistance degree is unqualified; the coating is applied by degradable polyacrylic acid emulsion, and the coating weight is 15.9g/m²When the water absorption value of Cobb is 0.34g/m (2min)²The oil resistance grade of Kit is 12 grade, and the oil resistance is qualified; the talcum powder and polyacrylic emulsion mixed coating (mass ratio 50: 50) is applied in a single layer, and the coating weight is 19.2g/m²When the water absorption value of Cobb is 0.45g/m (2min)²The oil resistance grade of Kit is 12 grade, and the oil resistance is qualified; the talcum powder and polyacrylic emulsion mixed coating (mass ratio is 70: 30) are pre-coated on the base paper, and the coating weight is 7.2g/m²Then pure polyacrylic acid emulsion is coated on the surface, and the coating weight is 4.4g/m²The Cobb water absorption value (2min) is 0g/m²And the oil resistance grade of Kit is 12 grade, and the oil resistance is qualified.

Example 5:

weighing 300g of agate grinding beads, and putting the agate grinding beads into a grinding tank of a planetary ball mill, wherein the agate grinding beads with the diameter of 15-25 mm account for 30% of the total mass of the grinding beads, and the agate grinding beads with the diameter of 10-15 mm account for 70% of the total mass of the grinding beads; weighing 1250-mesh talcum powder 30g, putting the talcum powder into a grinding tank, adding water 2g, adding a wetting agent 0.15g, a grinding dispersant 0.6g and a foam inhibitor 0.003 g; and (3) starting the grinding machine, controlling the rotating speed to be 1000rpm, supplementing 0.3g of grinding dispersant after grinding for 0.5h, stopping after continuing grinding for 0.5h, and drying in an oven to obtain the dry powder of the talcum powder pigment. After grinding by a mortar, the average particle size of the talcum powder is 2.350 micrometers, the median diameter is 1.551 micrometers, and the number of particles smaller than 2 micrometers is 59.2 percent; the talcum powder is in a sheet shape and the diameter-thickness ratio reaches 83 when observed by a scanning electron microscope.