Silicon dioxide plastic film opening agent as well as preparation method and application thereof

Abstract

The invention provides a silicon dioxide plastic film anti-blocking agent as well as a preparation method and application thereof, and the preparation method of the anti-blocking agent comprises the following steps: diluting sodium silicate with water, heating to 40-60 DEG C, dropwise adding a sulfuric acid solution, and stirring for reaction until the pH is 8-10 to obtain a gel solution; adding an imidazole-containing silane coupling agent and magnesium stearate into the gel solution, heating to 80-100 DEG C, carrying out stirring reaction, dropwise adding a sulfuric acid solution, and carrying out stirring reaction until the pH value is 3-5 to obtain precipitate slurry; and filtering and washing the precipitate slurry, pulping, carrying out spray drying, and crushing to obtain the silicon dioxide plastic film opening agent. According to the silicon dioxide plastic film opening agent as well as the preparation method and the application thereof, the opening agent has the characteristics of high specific surface area and proper oil absorption value, can be effectively adsorbed at the tail end of a molecular chain of a plastic film, improves the opening ratio of the plastic film, also improves the dispersity of the opening agent in the plastic film, and improves the anti-blocking performance of the plastic film. And good processability is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of silicon dioxide, and in particular to a silicon dioxide plastic film opening agent and a preparation method and application thereof. Background Art

[0002] With the rapid development of the national economy, the demand for plastics has grown rapidly, driving the production of plastic films into a historical peak. Plastic films are widely used in food packaging, medical packaging, cultural products packaging and agricultural films. However, during the process of winding and storage of plastic films, the film layers are prone to adhesion due to heat or pressure, which affects the unwinding speed of the subsequent processing, or even makes it impossible to unfold and use. There are two main reasons for the adhesion of plastic films: one is that after the film is closed, a vacuum seal is formed between the films, which is not easy to separate; the other is that after the film is formed, there are a large number of exposed molecular chains on its surface, and after the two films are closed, the macromolecular chains are entangled with each other, making it impossible to open. Therefore, in order to solve this phenomenon, an opening agent is often added to the plastic film to form microscopic unevenness on the surface of the plastic film, which prevents the entanglement between low molecular weight substances and plays an anti-adhesion role.

[0003] There are three generations of plastic film opening agents: the first generation is talcum powder, diatomaceous earth, calcium hydrogen phosphate, etc., whose disadvantages are poor opening performance and the addition affects the optical and other physical and chemical properties of plastic films. The second generation is oleic acid amide and ethylene bis stearamide (EBS) derivatives, etc., whose disadvantages are that the organic opening agent precipitates are attached to the surface of the film, affecting the printability, heat sealing and color of the film, and also affecting its safety as a food packaging material. The third generation is synthetic silica, which has the advantages of good opening performance and non-toxicity, but because silica itself is a hydrophilic substance, its dispersibility and compatibility in plastic films are very poor, which affects the transparency and tensile strength of the plastic film, and thus affects the quality of the plastic film.

[0004] As the requirements for the quality of plastic films gradually increase, the requirements for their transparency, opening, tensile strength, tear strength and other properties are becoming more and more stringent. These properties of plastic films are directly related to the performance of silica opening agents. Summary of the invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a silicon dioxide plastic film opening agent and a preparation method and application thereof. The opening agent has the characteristics of high specific surface area and suitable oil absorption value, can be effectively adsorbed at the end of the plastic film molecular chain, and improves the opening rate of the plastic film while also improving its dispersibility in the plastic film, thereby obtaining good processing performance.

[0006] The present invention provides a method for preparing a silicon dioxide plastic film opening agent, comprising the following steps:

[0007] S1, dilute sodium silicate with water, raise the temperature to 40-60°C, add sulfuric acid solution dropwise, stir and react until the pH is 8-10, and obtain a gel solution;

[0008] S2, adding an imidazole-containing silane coupling agent and magnesium stearate to the gel solution, heating to 80-100° C. and stirring to react, then dropping a sulfuric acid solution, stirring to react until the pH is 3-5, to obtain a precipitate slurry;

[0009] S3, filtering, washing, beating, atomizing, drying and crushing the precipitate slurry to obtain the silicon dioxide plastic film opening agent.

[0010] In the present invention, a sodium silicate solution is rapidly polymerized in an initial alkaline environment, thereby promoting the rapid generation of silicon dioxide, and the generated particles are small and have good dispersibility; thereafter, an imidazole-containing silane coupling agent and magnesium stearate are added, and the imidazole-containing silane coupling agent is hydrolyzed to generate silanol, which can form a condensation with a hydroxyl group on the silicon surface of a silicon dioxide particle, so that an imidazole group is grafted on the surface of a silicon dioxide crystal particle, which, on the one hand, reduces the hydroxyl group on the surface of the silicon dioxide, forms a steric hindrance on the surface of the silicon dioxide, hinders the secondary agglomeration of the silicon dioxide particles, controls the particle size, and improves the dispersibility; on the other hand, the grafted imidazole group can be complexed with the magnesium ion in the magnesium stearate, so that the magnesium stearate is adsorbed on the surface of the silicon dioxide, which can not only further improve the particle fluidity of the silicon dioxide, further increase the dispersibility of the silicon dioxide in the plastic film, but also increase the packing density of the silicon dioxide, and avoid particle agglomeration.

[0011] Preferably, in step S1, the modulus of the sodium silicate is 3-3.5;

[0012] Preferably, the sodium silicate is diluted with water to a concentration of 0.5-2.5 mol / L.

[0013] Preferably, in step S1, the concentration of the sulfuric acid solution is 0.1-1 mol / L.

[0014] Preferably, in step S2, the imidazole-containing silane coupling agent is obtained by addition reaction of vinyl imidazole and silicon hydride; the silicon hydride is preferably triethoxysilane;

[0015] Preferably, the amount of the imidazole-containing silane coupling agent is 1-5wt% of the sodium silicate, and the amount of the magnesium stearate is 0.1-0.5wt% of the sodium silicate.

[0016] In the present invention, vinyl imidazole can be used as an unsaturated compound to react with a silicon hydride compound to produce a hydrosilylation reaction, thereby preparing an imidazole-containing silane coupling agent, the structure of which is shown as follows:

[0017]

[0018] Preferably, in step S2, the concentration of the sulfuric acid solution is 5-10 mol / L.

[0019] Preferably, in step S3, the filtering and washing are performed until the mass percentage of sodium ions is less than 0.1%.

[0020] Preferably, in step S3, the atomization drying is performed until the mass percentage of moisture is less than 3%.

[0021] Preferably, in step S3, the pulverization is air flow pulverization, and the pulverization is performed until the average particle size of the opening agent is 3-4 μm.

[0022] The present invention also provides a silicon dioxide plastic film opening agent, which is prepared by the above preparation method.

[0023] The present invention also provides an application of the above-mentioned opening agent in a plastic film.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The preparation method provided by the present invention, by adjusting the initial concentration, reaction temperature, reaction pH, sulfuric acid concentration, etc., makes the prepared opening agent have the characteristics of high specific surface area, high porosity, and suitable oil absorption value, which can effectively adsorb the macromolecular chains exposed on the surface of the film molecules, solve the problem of macromolecular chain entanglement between the films, significantly reduce the static / dynamic friction, and improve the opening effect.

[0026] (2) The present invention improves the surface properties of silicon dioxide particles by adding imidazole-containing silane coupling agents and magnesium stearate, greatly improving the affinity between the anti-blocking agent and the organic polymer of the plastic film, and has very little effect on the increase of haze in the plastic film, and has high transparency. DETAILED DESCRIPTION

[0027] The technical solutions of the present invention are described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustration only and are not to be construed as limiting the scope of the present invention.

[0028] Example 1

[0029] A method for preparing a silicon dioxide plastic film opening agent comprises the following steps:

[0030] (1) diluting solid sodium silicate with a modulus of 3.2 with distilled water to a concentration of 1.5 mol / L, heating the solution to 50° C., dripping a 0.5 mol / L sulfuric acid solution into the sodium silicate dilute solution, stirring the solution to react until the pH value reaches 9, and aging the solution for 50 min to obtain a gel solution;

[0031] (2) adding an imidazole-containing silane coupling agent and magnesium stearate to the gel solution, wherein the amount of the imidazole-containing silane coupling agent is 3wt% of the mass of the sodium silicate, and the amount of the magnesium stearate is 0.3wt% of the mass of the sodium silicate; heating the solution to 90° C. and stirring the solution for reaction for 30 min; then dropping a 7.5 mol / L sulfuric acid solution, stirring the solution until the pH value is 4, and aging the solution for 100 min to obtain a precipitate slurry;

[0032] The imidazole-containing silane coupling agent is prepared by the following method: 1-vinylimidazole and 1wt% of tetrakis(triphenylphosphine)platinum by weight of 1-vinylimidazole are added to triethoxysilane by weight of 10 times the weight of 1-vinylimidazole, the mixture is heated to 80°C and stirred for reaction for 36h, cooled, washed with ether, and the solvent is removed by rotary evaporation to obtain the imidazole-containing silane coupling agent;

[0033] (3) The precipitate slurry is filtered and washed with deionized water until the mass percentage of sodium ions is less than 0.1%, and then slurried with high-speed stirring. The obtained slurry is spray-dried to a water mass percentage of less than 3%, and air flow pulverized to an average particle size of 3.5 μm to obtain the silicon dioxide plastic film opening agent.

[0034] Example 2

[0035] A method for preparing a silicon dioxide plastic film opening agent comprises the following steps:

[0036] (1) diluting solid sodium silicate with a modulus of 3.2 with distilled water to a concentration of 0.5 mol / L, heating the solution to 60° C., dripping a sulfuric acid solution with a concentration of 0.1 mol / L into the sodium silicate dilute solution, stirring the solution to react until the pH reaches 8, and aging the solution for 50 min to obtain a gel solution;

[0037] (2) adding an imidazole-containing silane coupling agent and magnesium stearate to the gel solution, wherein the amount of the imidazole-containing silane coupling agent is 5wt% of the mass of the sodium silicate, and the amount of the magnesium stearate is 0.1wt% of the mass of the sodium silicate; heating the solution to 100° C. and stirring the solution for reaction for 30 min; then dropping a 5 mol / L sulfuric acid solution, stirring the solution until the pH value is 5, and aging the solution for 100 min to obtain a precipitate slurry;

[0038] The imidazole-containing silane coupling agent is prepared by the following method: 1-vinylimidazole and 1wt% of tetrakis(triphenylphosphine)platinum by weight of 1-vinylimidazole are added to triethoxysilane by weight of 10 times the weight of 1-vinylimidazole, the mixture is heated to 80°C and stirred for reaction for 36h, cooled, washed with ether, and the solvent is removed by rotary evaporation to obtain the imidazole-containing silane coupling agent;

[0039] (3) The precipitate slurry is filtered and washed with deionized water until the mass percentage of sodium ions is less than 0.1%, and then slurried with high-speed stirring. The obtained slurry is spray-dried to a water mass percentage of less than 3%, and air flow pulverized to an average particle size of 3.5 μm to obtain the silicon dioxide plastic film opening agent.

[0040] Example 3

[0041] A method for preparing a silicon dioxide plastic film opening agent comprises the following steps:

[0042] (1) diluting solid sodium silicate with a modulus of 3.2 with distilled water to a concentration of 2.5 mol / L, heating to 40° C., dripping a sulfuric acid solution with a concentration of 1 mol / L into the sodium silicate dilute solution, stirring the reaction until the pH reaches 10, and aging for 50 min to obtain a gel solution;

[0043] (2) adding an imidazole-containing silane coupling agent and magnesium stearate to the gel solution, wherein the amount of the imidazole-containing silane coupling agent is 1wt% of the mass of the sodium silicate, and the amount of the magnesium stearate is 0.5wt% of the mass of the sodium silicate; heating the solution to 80° C. and stirring the solution for reaction for 30 min; then dropping a 10 mol / L sulfuric acid solution, stirring the solution for reaction until the pH value is 3, and aging the solution for 100 min to obtain a precipitate slurry;

[0044] The imidazole-containing silane coupling agent is prepared by the following method: 1-vinylimidazole and 1wt% of tetrakis(triphenylphosphine)platinum by weight of 1-vinylimidazole are added to triethoxysilane by weight of 10 times of 1-vinylimidazole, the mixture is heated to 80°C and stirred for reaction for 36h, cooled, washed with ether, and the solvent is removed by rotary evaporation to obtain the imidazole-containing silane coupling agent;

[0045] (3) The precipitate slurry is filtered and washed with deionized water until the mass percentage of sodium ions is less than 0.1%, and then slurried with high-speed stirring. The obtained slurry is spray-dried to a water mass percentage of less than 3%, and air flow pulverized to an average particle size of 3.5 μm to obtain the silicon dioxide plastic film opening agent.

[0046] Comparative Example 1

[0047] A method for preparing a silicon dioxide plastic film opening agent comprises the following steps:

[0048] (1) diluting solid sodium silicate with a modulus of 3.2 with distilled water to a concentration of 1.5 mol / L, heating the solution to 50° C., dripping a 0.5 mol / L sulfuric acid solution into the sodium silicate dilute solution, stirring the solution to react until the pH value reaches 9, and aging the solution for 50 min to obtain a gel solution;

[0049] (2) heating the gel solution to 90° C., then dropping a 7.5 mol / L sulfuric acid solution, stirring the mixture until the pH value reaches 4, and aging the mixture for 100 min to obtain a precipitate slurry;

[0050] (3) The precipitate slurry is filtered and washed with deionized water until the mass percentage of sodium ions is less than 0.1%, and then slurried with high-speed stirring. The obtained slurry is spray-dried to a water mass percentage of less than 3%, and air flow pulverized to an average particle size of 3.5 μm to obtain the silicon dioxide plastic film opening agent.

[0051] Comparative Example 2

[0052] A method for preparing a silicon dioxide plastic film opening agent comprises the following steps:

[0053] (1) diluting solid sodium silicate with a modulus of 3.2 with distilled water to a concentration of 1.5 mol / L, heating the solution to 50° C., dripping a 0.5 mol / L sulfuric acid solution into the sodium silicate dilute solution, stirring the solution to react until the pH value reaches 9, and aging the solution for 50 min to obtain a gel solution;

[0054] (2) adding magnesium stearate to the gel solution, wherein the amount of magnesium stearate is 0.3 wt % of the mass of sodium silicate, heating to 90° C. and stirring for reaction for 30 min, then dropping a 7.5 mol / L sulfuric acid solution, stirring for reaction until the pH value is 4, and aging for 100 min to obtain a precipitate slurry;

[0055] (3) The precipitate slurry is filtered and washed with deionized water until the mass percentage of sodium ions is less than 0.1%, and then slurried with high-speed stirring. The obtained slurry is spray-dried to a water mass percentage of less than 3%, and air flow pulverized to an average particle size of 3.5 μm to obtain the silicon dioxide plastic film opening agent.

[0056] Performance Test:

[0057] The specific surface area of ​​the opening agent is measured with reference to the measurement method in the national standard GB / T 19587-2004; the bulk density of the opening agent is measured with reference to the measurement method of bulk density in the national standard GB / T 20316.1-2009; the oil absorption value of the opening agent is measured with reference to the measurement method of oil absorption value in the industry standard HG / T 3072-2019.

[0058] Table 1 Performance test results of the opening agent described in the examples and comparative examples

[0059]

[0060] As shown in the results in Table 1, the anti-blocking agent prepared by the method described in the embodiment of the present invention has a large specific surface area, a bulk density of more than 0.45 g / ml, and a moderate oil absorption value.

[0061] Polypropylene (F800EDF) and opening agent are added to a high mixer in a mass ratio of 90:10 for mixing at a rotation speed of 150r / min. The resulting mixture is added to a twin-screw extruder for granulation. The 10-section temperatures are 175°C, 185°C, 190°C, 190°C, 190°C, 190°C, 190°C, 185°C, 190°C and 190°C respectively to obtain a masterbatch, which is then added to a casting machine for casting sample preparation. The main machine is set to 10Hz, and the temperatures from the first zone of the screw to the die lip are 190°C, 195°C, 200°C, 200°C, 200°C, 215°C, 210°C, 210°C, 210°C and 210°C respectively. The chilled roller is 25°C to obtain a plastic film.

[0062] The dynamic / static friction coefficient of the plastic film is measured according to the measurement method in the national standard GB / T10006-2021; the light transmittance / haze of the plastic film is measured according to the measurement method in the national standard GB2410-2008.

[0063] Table 2 Performance test results of the plastic film corresponding to the opening agent of the embodiment and the comparative example

[0064]

[0065]

[0066] As shown in the results in Table 1, after the opening agent prepared by the method described in the embodiment of the present invention is applied to the plastic film, the light transmittance is significantly improved, the haze is effectively reduced, and the friction coefficient is also significantly reduced, so that the opening performance is improved.

[0067] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a silicon dioxide plastic film opening agent, characterized in that: The steps include: S1, dilute sodium silicate with water, raise the temperature to 40-60°C, add sulfuric acid solution dropwise, stir and react until the pH is 8-10, and obtain a gel solution; S2, adding an imidazole-containing silane coupling agent and magnesium stearate to the gel solution, heating to 80-100° C. and stirring to react, then dropping a sulfuric acid solution, stirring to react until the pH is 3-5, to obtain a precipitate slurry; S3, filtering, washing, beating, atomizing, drying and crushing the precipitate slurry to obtain the silicon dioxide plastic film opening agent.

2. The method for preparing the silicon dioxide plastic film opening agent according to claim 1, characterized in that: In step S1, the modulus of the sodium silicate is 3-3.5; Preferably, the sodium silicate is diluted with water to a concentration of 0.5-2.5 mol / L.

3. The method for preparing the silicon dioxide plastic film opening agent according to claim 1 or 2, characterized in that: In step S1, the concentration of the sulfuric acid solution is 0.1-1 mol / L.

4. The method for preparing the silicon dioxide plastic film opening agent according to any one of claims 1 to 3, characterized in that: In step S2, the imidazole-containing silane coupling agent is obtained by addition reaction of vinyl imidazole and silicon hydride; the silicon hydride is preferably triethoxysilane; Preferably, the amount of the imidazole-containing silane coupling agent is 1-5wt% of the sodium silicate, and the amount of the magnesium stearate is 0.1-0.5wt% of the sodium silicate.

5. The method for preparing the silicon dioxide plastic film opening agent according to any one of claims 1 to 4, characterized in that: In step S2, the concentration of the sulfuric acid solution is 5-10 mol / L.

6. The method for preparing the silicon dioxide plastic film opening agent according to any one of claims 1 to 5, characterized in that: In step S3, the filtering and washing are performed until the mass percentage of sodium ions is less than 0.1%.

7. The method for preparing the silicon dioxide plastic film opening agent according to any one of claims 1 to 6, characterized in that: In step S3, the atomization drying is performed until the mass percentage of water is less than 3%.

8. The method for preparing the silicon dioxide plastic film opening agent according to any one of claims 1 to 7, characterized in that: In step S3, the pulverization is air flow pulverization, and the pulverization is performed until the average particle size of the opening agent is 3-4 μm.

9. A silicon dioxide plastic film opening agent, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the opening agent according to claim 9 in a plastic film.

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