Ultrafine talcum powder and preparation method thereof

Abstract

The present invention belongs to the technical field of talcum powder preparation, and specifically relates to an ultrafine talcum powder and a preparation method thereof. The preparation method of the ultrafine talcum powder provided by the present invention comprises the following steps: mixing talcum powder, vinyl triethoxysilane and an organic solvent, heating and reacting to obtain vinyl triethoxysilane-modified talcum powder; mixing vinyl triethoxysilane-modified talcum powder, diethyl allyl malonate, methacrylic acid, an emulsifier and water, and then adding an initiator aqueous solution and sodium bicarbonate, heating and stirring to react, and obtaining a secondary modified talcum powder; placing the secondary modified talcum powder in a sulfuric acid ethanol solution, heating and stirring, and wet grinding to obtain the ultrafine talcum powder. The ultrafine talcum powder obtained by the above method of the present invention is applied to the polypropylene doping process to effectively improve the tensile strength and impact strength of polypropylene.

Description

Technical Field

[0001] The invention belongs to the technical field of talcum powder preparation, and particularly relates to ultrafine talcum powder and a preparation method thereof. Background Art

[0002] Talc has excellent properties such as good heat resistance, lubrication, and insulation, and is widely used in papermaking, rubber, plastics and other fields. Talc is a hydrated silicate with a chemical formula of 3MgO.4SiO2.H2O. Its crystal shape can be flake, leaf, needle or block. Talc has an interlayer structure, and the layers can be combined by van der Waals force. When subjected to external force, the layers can slide relative to each other. When used as a filling material for plastics, it can enhance the mechanical properties of plastics and give the materials new properties. With the continuous development of industry, higher and higher requirements are placed on the fineness of talc, especially ultrafine talc, which has a wider range of applications.

[0003] Polypropylene is a plastic with excellent performance, good dielectric properties and insulation properties. It does not react with most chemical reagents and has good chemical stability. However, its mechanical strength, especially tensile strength and impact strength, is low, which greatly limits its application. In order to improve the tensile strength and impact strength of polypropylene, it is generally necessary to dope it.

[0004] Ultrafine talcum powder is a good doping material that can improve the tensile strength and impact strength of polypropylene to a certain extent. However, ultrafine talcum powder has a small particle size and the particles are easy to agglomerate. It has weak affinity with polypropylene and poor compatibility and dispersion properties, which restricts the improvement of the strength of polypropylene after doping. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of limited tensile strength and impact strength of polypropylene obtained by doping polypropylene with ultrafine talcum powder in the prior art, and further provide an ultrafine talcum powder and a preparation method thereof.

[0006] To this end, the technical solution adopted by the present invention is:

[0007] A method for preparing ultrafine talcum powder comprises the following steps:

[0008] 1) mixing talcum powder, vinyl triethoxysilane and an organic solvent, heating for reaction, filtering after the reaction is completed, and drying to obtain vinyl triethoxysilane-modified talcum powder;

[0009] 2) mixing vinyl triethoxysilane modified talc, diethyl allyl malonate, methacrylic acid, an emulsifier and water, then adding an initiator aqueous solution and sodium bicarbonate under an inert atmosphere, heating and stirring to react, cooling after the reaction is completed, filtering, washing and drying to obtain a secondary modified talc;

[0010] 3) placing the secondary modified talcum powder in a sulfuric acid ethanol solution, heating and stirring, filtering, drying, and then wet grinding the dried material. After the wet grinding is completed, drying is performed to obtain the ultrafine talcum powder.

[0011] Preferably, in step 1), the mass ratio of talc, vinyltriethoxysilane and organic solvent is 10:(1.0-2.0):(120-200);

[0012] The organic solvent is ethanol.

[0013] Preferably, in step 1), the heating reaction temperature is 60-72° C. and the reaction time is 2-5 h.

[0014] Preferably, in step 2), the mass ratio of vinyltriethoxysilane-modified talc, diethyl allyl malonate, methacrylic acid, emulsifier and water is 10:(5-7):(0.8-2):(0.3-1):(20-60).

[0015] Preferably, in step 2), the mass ratio of vinyltriethoxysilane-modified talc, the initiator aqueous solution and sodium bicarbonate is 10:(3-8):(1-5).

[0016] Preferably, the initiator aqueous solution is a potassium persulfate aqueous solution, and the mass concentration of the potassium persulfate aqueous solution is 2-8%;

[0017] The emulsifier is selected from sodium allyl sulfonate;

[0018] The inert atmosphere is a nitrogen atmosphere.

[0019] Preferably, the heating and stirring reaction temperature in step 2) is 60-70°C, and the reaction time is 60-120min;

[0020] Step 2) The washing step uses water and ethanol to wash in sequence.

[0021] Preferably, the mass ratio of the secondary modified talcum powder to the sulfuric acid ethanol solution in step 3) is 1:(8-15);

[0022] The sulfuric acid ethanol solution is obtained by mixing sulfuric acid solution and ethanol, the mass ratio of the sulfuric acid solution to ethanol is 1:(8-12), and the mass concentration of the sulfuric acid solution is 2-6%.

[0023] Preferably, in step 3), the heating and stirring temperature is 38-45° C., and the heating and stirring time is 10-20 min.

[0024] Preferably, the particle size of the ultrafine talc powder is 1-5 microns.

[0025] The ultrafine talc powder obtained by the preparation method of the present invention can be applied to polypropylene doping modification. Optionally, the doping amount of the ultrafine talc powder accounts for 10-20% of the mass of the polypropylene.

[0026] The technical solution of the present invention has the following advantages:

[0027] The preparation method of ultrafine talc provided by the present invention comprises the following steps: firstly, talc is modified by using vinyl triethoxysilane to obtain vinyl triethoxysilane-modified talc; then, vinyl triethoxysilane-modified talc and specific diethyl allyl malonate are polymerized and grafted; during the polymerized grafting of diethyl allyl malonate, the ester group is further hydrolyzed and combined with the active hydroxyl group on the surface of the talc; in the modification process, vinyl triethoxysilane and diethyl allyl malonate are introduced; the combination of the two can effectively improve the affinity of the modified talc with polypropylene and improve its agglomeration; at the same time, diethyl allyl malonate is used as The chemical bond is connected with vinyl triethoxysilane and can be further combined with talcum powder through hydrolysis, which greatly improves the bonding strength with talcum powder. Furthermore, after the secondary modified talcum powder obtained by the modification treatment is heat-treated with sulfuric acid ethanol solution, the modified talcum powder further swells under the action of ethanol and sulfuric acid, which is conducive to the exposure of the grafted groups on the surface of the talcum powder to the surface of the talcum powder and tightly covering the surface of the talcum powder to form a more compact coating structure. The ultrafine talcum powder obtained by the above method and the steps cooperate with each other can be applied to the polypropylene doping process to effectively improve the tensile strength and impact strength of polypropylene. DETAILED DESCRIPTION

[0028] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0029] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0030] Example 1

[0031] This embodiment provides a method for preparing ultrafine talcum powder, comprising the following steps:

[0032] 1) 10 g of talc, 1.2 g of vinyltriethoxysilane and 150 g of ethanol were mixed, reacted at 70° C. for 3 h, filtered after the reaction, and dried to obtain vinyltriethoxysilane-modified talc;

[0033] 2) 10 g of vinyl triethoxysilane-modified talc, 5 g of diethyl allyl malonate, 1 g of methacrylic acid, 0.5 g of sodium allyl sulfonate and 40 g of water were mixed, and then 5 g of potassium persulfate aqueous solution (the concentration of potassium persulfate aqueous solution was 5%) and 2 g of sodium bicarbonate were added under a nitrogen atmosphere, and the mixture was stirred and reacted at 60° C. for 80 min. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed with water and ethanol in sequence, and dried to obtain a secondary modified talc;

[0034] 3) 10 g of 5% sulfuric acid solution and 100 g of ethanol are mixed to obtain a sulfuric acid ethanol solution; 5 g of the secondary modified talc is placed in 50 g of the sulfuric acid ethanol solution prepared above, heated and stirred at 40° C. for 15 min, filtered, dried, and then wet-grinded the dried material. After the wet grinding is completed, it is dried to obtain the ultrafine talc powder, and the particle size of the ultrafine talc powder is 3.5 microns.

[0035] Example 2

[0036] This embodiment provides a method for preparing ultrafine talcum powder, comprising the following steps:

[0037] 1) 10 g of talc, 1.6 g of vinyltriethoxysilane and 180 g of ethanol were mixed, reacted at 72° C. for 3 h, filtered after the reaction, and dried to obtain vinyltriethoxysilane-modified talc;

[0038] 2) 10 g of vinyl triethoxysilane-modified talc, 5.5 g of diethyl allyl malonate, 1 g of methacrylic acid, 0.5 g of sodium allyl sulfonate and 40 g of water were mixed, and then 5 g of potassium persulfate aqueous solution (the concentration of potassium persulfate aqueous solution was 5%) and 2 g of sodium bicarbonate were added under a nitrogen atmosphere, and the mixture was stirred at 65° C. for 80 min. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed with water and ethanol in turn, and dried to obtain a secondary modified talc;

[0039] 3) 10 g of 5% sulfuric acid solution and 110 g of ethanol are mixed to obtain a sulfuric acid ethanol solution; 5 g of the secondary modified talc is placed in 50 g of the sulfuric acid ethanol solution prepared above, heated and stirred at 40° C. for 15 min, filtered, dried, and then wet-grinded the dried material. After the wet grinding is completed, it is dried to obtain the ultrafine talc powder, and the particle size of the ultrafine talc powder is 3.5 microns.

[0040] Example 3

[0041] This embodiment provides a method for preparing ultrafine talcum powder, comprising the following steps:

[0042] 1) 10 g of talc, 1.8 g of vinyltriethoxysilane and 180 g of ethanol were mixed, reacted at 72° C. for 3 h, filtered after the reaction, and dried to obtain vinyltriethoxysilane-modified talc;

[0043] 2) 10 g of vinyl triethoxysilane-modified talc, 6.0 g of diethyl allyl malonate, 1.2 g of methacrylic acid, 0.6 g of sodium allyl sulfonate and 40 g of water were mixed, and then 5 g of potassium persulfate aqueous solution (the concentration of potassium persulfate aqueous solution was 5%) and 2 g of sodium bicarbonate were added under a nitrogen atmosphere, and the mixture was stirred at 70° C. for 70 min. After the reaction was completed, the mixture was cooled to room temperature, filtered, washed with water and ethanol in turn, and dried to obtain a secondary modified talc;

[0044] 3) 10 g of 5% sulfuric acid solution and 90 g of ethanol are mixed to obtain a sulfuric acid ethanol solution; 5 g of the secondary modified talc is placed in 50 g of the sulfuric acid ethanol solution prepared above, heated and stirred at 45° C. for 15 min, filtered, dried, and then wet-grinded the dried material. After the wet grinding is completed, it is dried to obtain the ultrafine talc powder, and the particle size of the ultrafine talc powder is 3.5 microns.

[0045] Comparative Example 1

[0046] This comparative example provides a method for preparing ultrafine talc powder, which differs from Example 1 in that in step 1), vinyltriethoxysilane is replaced by an equal molar amount of γ-aminopropyltriethoxysilane.

[0047] Comparative Example 2

[0048] This comparative example provides a method for preparing ultrafine talc, which differs from Example 1 in that in step 2), diethyl allylmalonate is replaced by an equal molar amount of methyl methacrylate.

[0049] Comparative Example 3

[0050] This comparative example provides a method for preparing ultrafine talc powder, which differs from Example 1 in that in step 3), 5 g of secondary modified talc powder is wet-ground, and after the wet grinding, it is dried to obtain the ultrafine talc powder, and the particle size of the ultrafine talc powder is 3.5 microns.

[0051] Comparative Example 4

[0052] This comparative example provides a method for preparing ultrafine talc powder, which differs from Example 1 in that in step 3), 5 g of secondary modified talc powder is placed in 50 g of ethanol, heated and stirred at 40° C. for 15 min, filtered, dried, and then the dried material is wet-ground. After the wet grinding is completed, it is dried to obtain the ultrafine talc powder, and the particle size of the ultrafine talc powder is 3.5 μm.

[0053] Test Case

[0054] The ultrafine talc powder prepared in the above embodiments and comparative examples was mixed with polypropylene (model BX3800) in a mixer (the amount of ultrafine talc powder was 15% of the mass of polypropylene), the mixed materials were mixed in an internal mixer and then extruded into granules, and then injection molded by an injection machine to prepare samples, and the performance of the samples was tested, wherein the tensile strength was tested according to GB / T1040-2006; the impact strength was tested according to GB / T1043-1993.

[0055] The test results are shown in Table 1.

[0056] Table 1

[0057] sample Tensile strength / MPa <![CDATA[Impact strength / (KJ / m 2 )]]> Example 1 32 29 Example 2 34 30 Example 3 35 32 Comparative Example 1 24 23 Comparative Example 2 26 24 Comparative Example 3 28 26 Comparative Example 4 29 27

[0058] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing ultrafine talcum powder, characterized in that: The steps include: 1) mixing talcum powder, vinyl triethoxysilane and an organic solvent, heating for reaction, filtering after the reaction, and drying to obtain vinyl triethoxysilane modified talcum powder; 2) Vinyl triethoxysilane modified talc, diethyl allyl malonate, methacrylic acid, an emulsifier and water are mixed, and then an initiator aqueous solution and sodium bicarbonate are added under an inert atmosphere, and the mixture is heated and stirred for reaction. After the reaction is completed, the mixture is cooled, filtered, washed and dried to obtain a secondary modified talc; 3) placing the secondary modified talc in a sulfuric acid ethanol solution, heating and stirring, filtering, drying, and then wet grinding the dried material. After the wet grinding is completed, drying is performed to obtain the ultrafine talc; In step 2), the mass ratio of vinyltriethoxysilane-modified talc, diethyl allyl malonate, methacrylic acid, emulsifier and water is 10: (5-7): (0.8-2): (0.3-1): (20-60); In step 2), the mass ratio of vinyltriethoxysilane-modified talc, initiator aqueous solution and sodium bicarbonate is 10:(3-8):(1-5); The initiator aqueous solution is a potassium persulfate aqueous solution, and the mass concentration of the potassium persulfate aqueous solution is 2-8%; The mass ratio of the secondary modified talcum powder to the sulfuric acid ethanol solution in step 3) is 1: (8-15); The sulfuric acid ethanol solution is obtained by mixing a sulfuric acid solution and ethanol, the mass ratio of the sulfuric acid solution to the ethanol is 1:(8-12), and the mass concentration of the sulfuric acid solution is 2-6%.

2. The method for preparing ultrafine talcum powder according to claim 1, characterized in that: In step 1), the mass ratio of talc, vinyltriethoxysilane and organic solvent is 10:(1.0-2.0):(120-200); The organic solvent is ethanol.

3. The method for preparing ultrafine talcum powder according to claim 1 or 2, characterized in that, In step 1), the heating reaction temperature is 60-72° C. and the reaction time is 2-5 h.

4. The method for preparing ultrafine talcum powder according to claim 1, characterized in that: The emulsifier is selected from sodium allyl sulfonate; The inert atmosphere is a nitrogen atmosphere.

5. The method for preparing ultrafine talcum powder according to claim 1, characterized in that: In step 2), the heating and stirring reaction temperature is 60-70°C and the reaction time is 60-120min; Step 2) The washing step uses water and ethanol to wash in sequence.

6. The method for preparing ultrafine talcum powder according to claim 1, characterized in that: In step 3), the heating and stirring temperature is 38-45° C., and the heating and stirring time is 10-20 min.

7. The method for preparing ultrafine talcum powder according to claim 1, characterized in that: The particle size of the ultrafine talc powder is 1-5 microns.