A kind of high foaming ratio thermal expansion microsphere and preparation method thereof

Abstract

The invention relates to the technical field of polymer microspheres, in particular to a high-foaming-ratio heat-expandable microsphere and a preparation method thereof. The high-foaming-ratio heat-expandable microsphere is composed of the following raw materials in parts by weight: 10-15 parts of acrylonitrile, 12-15 parts of methyl methacrylate, 10-14 parts of butyl acrylate, 8-14 parts of hydroxyethyl methacrylate, 4-7 parts of a foaming agent, 4-8 parts of a dispersant, 3-6 parts of benzoyl peroxide, 2-3 parts of p-divinylbenzene, 2-3 parts of hydroquinone, 2-3 parts of sodium nitrate, 4-8 parts of polyvinylpyrrolidone and 30-40 parts of deionized water. The high-foaming-ratio heat-expandable microsphere prepared by the invention has not only a low expansion temperature, but also a wide expansion temperature range, and also has an excellent expansion ratio, thereby effectively ensuring its quality.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer microspheres, in particular to high-foaming-ratio thermal expansion microspheres and a preparation method thereof. Background Art

[0002] Thermally expandable microspheres are functional polymer particles with a core / shell structure. The core is typically composed of a hydrocarbon, and the shell is a thermoplastic polymer. When heated to a certain temperature, the hydrocarbon vaporizes, generating pressure that causes the microspheres to rapidly expand, exhibiting unique thermal expansion properties. These properties have led to their widespread application in a variety of fields. For example, adding thermally expandable microspheres to coatings can create coatings with properties such as thermal insulation; using them in plastics can achieve lightweighting and improve cushioning properties; and in the papermaking industry, they can impart a unique texture and feel to paper.

[0003] Many common thermal expansion microspheres on the market currently have the problem of relatively high foaming starting temperature. The higher foaming temperature limits their use in some temperature-sensitive material systems or application scenarios, and conventional thermal expansion microspheres cannot meet the requirements.

[0004] Based on this, the present invention provides a high foaming ratio thermal expansion microsphere and a preparation method thereof to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-expansion-ratio thermal expansion microsphere and a preparation method thereof. The prepared high-expansion-ratio thermal expansion microsphere not only has a low expansion temperature, but also has a wide expansion temperature range, and also has an excellent expansion ratio, effectively ensuring its quality.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The first aspect of the present invention provides a high-expansion-ratio thermally expandable microsphere, which is composed of the following raw materials in parts by weight: 10 to 15 parts of acrylonitrile, 12 to 15 parts of methyl methacrylate, 10 to 14 parts of butyl acrylate, 8 to 14 parts of hydroxyethyl methacrylate, 4 to 7 parts of a foaming agent, 4 to 8 parts of a dispersant, 3 to 6 parts of benzoyl peroxide, 2 to 3 parts of p-divinylbenzene, 2 to 3 parts of hydroquinone, 2 to 3 parts of sodium nitrate, 4 to 8 parts of polyvinyl pyrrolidone and 30 to 40 parts of deionized water.

[0008] The present invention is further configured as follows: the foaming agent is formed by mixing the first base material and the second base material in a mass ratio of 1:0.2-0.3.

[0009] The present invention is further configured as follows: the first base material is prepared by mixing n-pentane and isopentane in a mass ratio of 1:0.6-0.8.

[0010] The present invention is further configured as follows: the preparation process of the second base material is as follows:

[0011] The carbon nanospheres are placed in ultrapure water at a dosage of 0.01 to 0.04 g / mL and ultrasonically dispersed for 15 to 20 minutes to obtain a dispersion;

[0012] Under the condition of a water bath at 1-5° C., the mixed acid is added dropwise to the obtained dispersion, and the mixture is stirred and mixed at 200-300 r / min. After the addition is completed, the temperature is raised to 70-78° C. and the stirring is continued for 180-200 min. The mixture is cooled to room temperature and centrifuged at 8000-10000 r / min for 10-15 min. The supernatant is discarded, and the mixture is washed with ultrapure water for 2-4 times, and then dried in a vacuum drying oven to constant weight to obtain modified carbon nanospheres;

[0013] The modified carbon nanospheres, sodium carbonate powder, and concentrated sulfuric acid with a mass concentration of 97-98% are placed in anhydrous ethanol, magnetically stirred at room temperature for 10-15 minutes, naturally cooled to room temperature, centrifuged at 7000-9000 r / min for 10-15 minutes, the supernatant is discarded, and the mixture is washed with anhydrous ethanol 2-4 times, and then placed in a vacuum drying oven to dry to constant weight to obtain a second base material.

[0014] The present invention is further configured as follows: the mixed acid is formed by mixing concentrated nitric acid with a mass concentration of 65-68% and concentrated sulfuric acid with a mass concentration of 97-98% in a volume ratio of 1:1.8-2.8, the dropwise addition amount of the mixed acid is 4.2-8.5% of the mass of the carbon nanospheres, and the dropwise addition time is 20-30 minutes.

[0015] The present invention is further configured as follows: the added mass ratio of the modified carbon nanospheres, sodium carbonate powder and concentrated sulfuric acid with a mass concentration of 97-98% is 1:0.5-0.8:0.05-0.1, and the total mass of the modified carbon nanospheres, sodium carbonate powder and concentrated sulfuric acid with a mass concentration of 97-98% is 22-32% of the mass of anhydrous ethanol.

[0016] The present invention is further configured as follows: the dispersant is formed by mixing nano silicon dioxide and polyvinyl alcohol in a mass ratio of 1:0.3-0.5.

[0017] The second aspect of the present invention further provides a method for preparing the above-mentioned high expansion ratio thermally expandable microspheres, comprising the following steps:

[0018] Step 1: Accurately weigh acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, a dispersant, benzoyl peroxide, p-divinylbenzene, hydroquinone, sodium nitrate, polyvinyl pyrrolidone, and deionized water, and set aside;

[0019] Step 2: placing the dispersant, polyvinyl pyrrolidone, hydroquinone and sodium nitrate in deionized water, stirring at 800-1000 rpm for 6-10 minutes to obtain an aqueous phase;

[0020] Step 3: placing acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, benzoyl peroxide, and p-divinylbenzene in a mixing device, and stirring at 200-300 r / min for 10-12 minutes to obtain an oil phase substance;

[0021] Step 4: Place the oil phase substance in the water phase substance, continue stirring at 800-1000 r / min for 5-8 minutes, then polymerize and stir under a nitrogen atmosphere at 0.4-0.5 MPa. After cooling to room temperature, filter, wash, and dry to obtain a finished product of high-expansion-ratio thermal expansion microspheres.

[0022] The present invention is further configured as follows: in step 4, the polymerization stirring speed is 380-400 r / min, the temperature is 68-72° C., and the time is 22-24 h.

[0023] The present invention is further configured as follows: in step 4, the washing is performed 2 to 4 times with deionized water.

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

[0025] The present invention uses acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, a dispersant, benzoyl peroxide, p-divinylbenzene, hydroquinone, sodium nitrate, polyvinyl pyrrolidone and deionized water as raw materials, and the dispersant, polyvinyl pyrrolidone, hydroquinone and sodium nitrate are placed in deionized water and stirred to obtain an aqueous phase material, and then acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, benzoyl peroxide and p-divinylbenzene are placed in a mixing device and stirred to obtain an oil phase material, and finally the oil phase material is placed in the aqueous phase material and continued to be stirred, and polymerized and stirred under a nitrogen atmosphere, after cooling to room temperature, filtered, washed and dried to obtain a finished product of high expansion ratio heat-expandable microspheres. The high expansion ratio heat-expandable microspheres prepared by the present invention not only have a lower expansion temperature, but also have a wider expansion temperature range, and also have an excellent expansion ratio, effectively ensuring its quality and quality. The high-expansion-ratio thermally expandable microspheres and the preparation method thereof provided by the present invention have a broader market prospect and are more suitable for promotion. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] Example 1

[0028] This embodiment provides a high-expansion ratio thermally expandable microsphere, which is composed of the following raw materials in parts by weight: 10 parts of acrylonitrile, 12 parts of methyl methacrylate, 10 parts of butyl acrylate, 8 parts of hydroxyethyl methacrylate, 4 parts of a foaming agent, 4 parts of a dispersant, 3 parts of benzoyl peroxide, 2 parts of p-divinylbenzene, 2 parts of hydroquinone, 2 parts of sodium nitrate, 4 parts of polyvinyl pyrrolidone and 30 parts of deionized water.

[0029] The foaming agent is prepared by mixing the first base material and the second base material in a mass ratio of 1:0.2.

[0030] Furthermore, the first base material is prepared by mixing n-pentane and isopentane in a mass ratio of 1:0.6.

[0031] Furthermore, the preparation process of the second base material is as follows:

[0032] The carbon nanospheres were placed in ultrapure water at a dosage of 0.01 g / mL and ultrasonically dispersed for 15 min to obtain a dispersion;

[0033] In a water bath at 1°C, the mixed acid was added dropwise to the obtained dispersion and stirred at 200 r / min. After the addition was completed, the temperature was raised to 70°C and the stirring was continued for 180 min. The dispersion was cooled to room temperature and centrifuged at 8000 r / min for 10 min. The supernatant was discarded, the mixture was washed twice with ultrapure water, and then dried in a vacuum drying oven to constant weight to obtain modified carbon nanospheres.

[0034] The modified carbon nanospheres, sodium carbonate powder, and concentrated sulfuric acid with a mass concentration of 97% are placed in anhydrous ethanol, magnetically stirred at room temperature for 10 minutes, naturally cooled to room temperature, centrifuged at 7000r / min for 10 minutes, the supernatant is discarded, and the mixture is washed twice with anhydrous ethanol, and then placed in a vacuum drying oven to dry to constant weight to obtain a second base material.

[0035] The mixed acid is prepared by mixing concentrated nitric acid with a mass concentration of 65% and concentrated sulfuric acid with a mass concentration of 97-98% in a volume ratio of 1:1.8. The amount of the mixed acid added is 4.2% of the mass of the carbon nanospheres, and the addition time is 20 minutes.

[0036] In addition, the added mass ratio of the modified carbon nanospheres, sodium carbonate powder and concentrated sulfuric acid with a mass concentration of 97% is 1:0.5:0.05, and the total mass of the modified carbon nanospheres, sodium carbonate powder and concentrated sulfuric acid with a mass concentration of 97% is 22% of the mass of anhydrous ethanol.

[0037] In this embodiment, it should be noted that the carbon nanospheres were purchased from Beijing Zhongke Keyou Nanotechnology Co., Ltd.

[0038] The dispersant is prepared by mixing nano-silicon dioxide and polyvinyl alcohol in a mass ratio of 1:0.3.

[0039] In this embodiment, it should be noted that nano-silica was purchased from Wuhan Kemik Biopharmaceutical Technology Co., Ltd.

[0040] In addition, this embodiment also provides a method for preparing the above-mentioned high expansion ratio thermally expandable microspheres, comprising the following steps:

[0041] Step 1: Accurately weigh acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, a dispersant, benzoyl peroxide, p-divinylbenzene, hydroquinone, sodium nitrate, polyvinyl pyrrolidone, and deionized water and set aside.

[0042] Step 2: Place the dispersant, polyvinyl pyrrolidone, hydroquinone and sodium nitrate in deionized water, and stir at 800 r / min for 6 minutes to obtain an aqueous phase material.

[0043] Step 3: Place acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, benzoyl peroxide and p-divinylbenzene in a mixing device and stir at 200 r / min for 10 minutes to obtain an oil phase substance.

[0044] Step 4: Place the oil phase substance in the water phase substance, continue stirring at 800 r / min for 5 minutes, then polymerize and stir under a nitrogen atmosphere and 0.4 MPa. After cooling to room temperature, filter, wash, and dry to obtain a finished product of high foaming ratio thermal expansion microspheres.

[0045] The polymerization stirring speed is 380 r / min, the temperature is 68° C., and the time is 22 h.

[0046] Washing was done twice with deionized water.

[0047] Example 2

[0048] The preparation method of the high foaming ratio heat-expandable microspheres provided in this embodiment is basically the same as that in Example 1, except that the specific raw material composition and the specific preparation method of the high foaming ratio heat-expandable microspheres in this embodiment are different. The specific raw material composition and the specific preparation method of the high foaming ratio heat-expandable microspheres in this embodiment are as follows:

[0049] A high-expansion-ratio thermal expansion microsphere is composed of the following raw materials in parts by weight: 12 parts of acrylonitrile, 13 parts of methyl methacrylate, 12 parts of butyl acrylate, 11 parts of hydroxyethyl methacrylate, 5 parts of a foaming agent, 6 parts of a dispersant, 4 parts of benzoyl peroxide, 3 parts of p-divinylbenzene, 3 parts of hydroquinone, 3 parts of sodium nitrate, 5 parts of polyvinyl pyrrolidone, and 35 parts of deionized water.

[0050] The foaming agent is prepared by mixing the first base material and the second base material in a mass ratio of 1:0.2.

[0051] Furthermore, the first base material is prepared by mixing n-pentane and isopentane in a mass ratio of 1:0.7.

[0052] Furthermore, the preparation process of the second base material is as follows:

[0053] The carbon nanospheres were placed in ultrapure water at a dosage of 0.02 g / mL and subjected to ultrasonic dispersion for 17 min to obtain a dispersion liquid;

[0054] The mixed acid was added dropwise to the obtained dispersion under 3°C water bath conditions and stirred at 250 r / min. After the addition was completed, the temperature was raised to 74°C and the stirring was continued for 190 min. The mixture was cooled to room temperature and centrifuged at 9000 r / min for 12 min. The supernatant was discarded, and the mixture was washed with ultrapure water three times and then dried in a vacuum drying oven to constant weight to obtain modified carbon nanospheres.

[0055] The modified carbon nanospheres, sodium carbonate powder, and concentrated sulfuric acid with a mass concentration of 98% are placed in anhydrous ethanol, magnetically stirred at room temperature for 12 minutes, naturally cooled to room temperature, centrifuged at 8000r / min for 12 minutes, the supernatant is discarded, and the mixture is washed with anhydrous ethanol three times, and then placed in a vacuum drying oven to dry to constant weight to obtain a second base material.

[0056] The mixed acid is prepared by mixing concentrated nitric acid with a mass concentration of 67% and concentrated sulfuric acid with a mass concentration of 97% in a volume ratio of 1:2.3. The amount of the mixed acid added is 6.3% of the mass of the carbon nanospheres, and the addition time is 25 minutes.

[0057] In addition, the added mass ratio of the modified carbon nanospheres, sodium carbonate powder and concentrated sulfuric acid with a mass concentration of 98% is 1:0.6:0.07, and the total mass of the modified carbon nanospheres, sodium carbonate powder and concentrated sulfuric acid with a mass concentration of 98% is 27% of the mass of anhydrous ethanol.

[0058] In this embodiment, it should be noted that the carbon nanospheres were purchased from Beijing Zhongke Keyou Nanotechnology Co., Ltd.

[0059] The dispersant is prepared by mixing nano-silicon dioxide and polyvinyl alcohol in a mass ratio of 1:0.4.

[0060] In this embodiment, it should be noted that nano-silica was purchased from Wuhan Kemik Biopharmaceutical Technology Co., Ltd.

[0061] In addition, this embodiment also provides a method for preparing the above-mentioned high expansion ratio thermally expandable microspheres, comprising the following steps:

[0062] Step 1: Accurately weigh acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, a dispersant, benzoyl peroxide, p-divinylbenzene, hydroquinone, sodium nitrate, polyvinyl pyrrolidone, and deionized water and set aside.

[0063] Step 2: Place the dispersant, polyvinyl pyrrolidone, hydroquinone and sodium nitrate in deionized water, and stir at 900 r / min for 8 minutes to obtain an aqueous phase material.

[0064] Step 3: Place acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, benzoyl peroxide and p-divinylbenzene in a mixing device and stir at 250 r / min for 11 minutes to obtain an oil phase substance.

[0065] Step 4: Place the oil phase substance in the water phase substance, continue stirring at 900 r / min for 6 minutes, then polymerize and stir under a nitrogen atmosphere and 0.5 MPa. After cooling to room temperature, filter, wash, and dry to obtain a finished product of high foaming ratio thermal expansion microspheres.

[0066] The polymerization stirring speed is 390 r / min, the temperature is 70° C., and the time is 23 h.

[0067] Washing was performed 3 times with deionized water.

[0068] Example 3

[0069] The preparation method of the high foaming ratio heat-expandable microspheres provided in this embodiment is basically the same as that in Example 1, except that the specific raw material composition and the specific preparation method of the high foaming ratio heat-expandable microspheres in this embodiment are different. The specific raw material composition and the specific preparation method of the high foaming ratio heat-expandable microspheres in this embodiment are as follows:

[0070] A high-expansion-ratio heat-expandable microsphere is composed of the following raw materials in parts by weight: 15 parts of acrylonitrile, 15 parts of methyl methacrylate, 14 parts of butyl acrylate, 14 parts of hydroxyethyl methacrylate, 7 parts of a foaming agent, 8 parts of a dispersant, 6 parts of benzoyl peroxide, 3 parts of p-divinylbenzene, 3 parts of hydroquinone, 3 parts of sodium nitrate, 8 parts of polyvinyl pyrrolidone, and 40 parts of deionized water.

[0071] The foaming agent is prepared by mixing the first base material and the second base material in a mass ratio of 1:0.3.

[0072] Furthermore, the first base material is prepared by mixing n-pentane and isopentane in a mass ratio of 1:0.8.

[0073] Furthermore, the preparation process of the second base material is as follows:

[0074] The carbon nanospheres were ultrasonically dispersed in ultrapure water at a dosage of 0.01 to 0.04 g / mL for 20 minutes to obtain a dispersion.

[0075] In a water bath at 5°C, the mixed acid was added dropwise to the obtained dispersion and stirred at 300 r / min. After the addition was completed, the temperature was raised to 78°C and the stirring was continued for 200 min. The mixture was cooled to room temperature and centrifuged at 10,000 r / min for 15 min. The supernatant was discarded, the mixture was washed with ultrapure water 4 times, and then dried in a vacuum drying oven to constant weight to obtain modified carbon nanospheres.

[0076] The modified carbon nanospheres, sodium carbonate powder, and concentrated sulfuric acid with a mass concentration of 98% are placed in anhydrous ethanol, magnetically stirred at room temperature for 15 minutes, naturally cooled to room temperature, centrifuged at 9000r / min for 15 minutes, the supernatant is discarded, and the mixture is washed with anhydrous ethanol 4 times, and then placed in a vacuum drying oven to dry to constant weight to obtain a second base material.

[0077] The mixed acid is prepared by mixing concentrated nitric acid with a mass concentration of 68% and concentrated sulfuric acid with a mass concentration of 97-98% in a volume ratio of 1:2.8. The amount of the mixed acid added is 8.5% of the mass of the carbon nanospheres, and the addition time is 30 minutes.

[0078] In addition, the added mass ratio of the modified carbon nanospheres, sodium carbonate powder and concentrated sulfuric acid with a mass concentration of 98% is 1:0.8:0.1, and the total mass of the modified carbon nanospheres, sodium carbonate powder and concentrated sulfuric acid with a mass concentration of 98% is 32% of the mass of anhydrous ethanol.

[0079] In this embodiment, it should be noted that the carbon nanospheres were purchased from Beijing Zhongke Keyou Nanotechnology Co., Ltd.

[0080] The dispersant is prepared by mixing nano-silicon dioxide and polyvinyl alcohol in a mass ratio of 1:0.5.

[0081] In this embodiment, it should be noted that nano-silica was purchased from Wuhan Kemik Biopharmaceutical Technology Co., Ltd.

[0082] In addition, this embodiment also provides a method for preparing the above-mentioned high expansion ratio thermally expandable microspheres, comprising the following steps:

[0083] Step 1: Accurately weigh acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, a dispersant, benzoyl peroxide, p-divinylbenzene, hydroquinone, sodium nitrate, polyvinyl pyrrolidone, and deionized water and set aside.

[0084] Step 2: Place the dispersant, polyvinyl pyrrolidone, hydroquinone and sodium nitrate in deionized water, and stir at 1000 r / min for 10 minutes to obtain an aqueous phase material.

[0085] Step 3: Place acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, benzoyl peroxide and p-divinylbenzene in a mixing device, and stir at 300 r / min for 12 minutes to obtain an oil phase substance.

[0086] Step 4: Place the oil phase substance in the water phase substance, continue stirring at 1000 r / min for 5 to 8 minutes, then polymerize and stir under a nitrogen atmosphere and 0.5 MPa. After cooling to room temperature, filter, wash, and dry to obtain a finished product of high-expansion-ratio thermal expansion microspheres.

[0087] The polymerization stirring speed is 400 r / min, the temperature is 72° C., and the time is 24 h.

[0088] Washing was performed 4 times with deionized water.

[0089] Comparative Example 1: The difference from Example 1 is that an equal amount of the first base material is used to replace the foaming agent in this example.

[0090] Comparative Example 2: The difference from Example 1 is that an equal amount of polyvinyl alcohol is used instead of the dispersant in this example.

[0091] Performance test: The high foaming ratio heat-expandable microsphere samples provided in Examples 1 to 3 and Comparative Examples 1 to 2 are marked as Examples 1 to 3 and Comparative Examples 1 to 2, respectively; and the relevant properties of the high foaming ratio heat-expandable microspheres provided in Examples 1 to 3 and Comparative Examples 1 to 2 are tested as follows:

[0092] 1. Thermal expansion performance test: The test method is to use a thermomechanical analyzer produced by Mettler Toledo. The test conditions are nitrogen atmosphere, heating rate of 10℃ / min, and probe pressure of 0.02N.

[0093] 2. Expansion ratio test: The test method is to measure the diameter of each group of thermal expansion microspheres before thermal expansion and after the temperature reaches the maximum thermal expansion temperature, and calculate the expansion diameter ratio = the diameter of the thermal expansion microspheres at the maximum thermal expansion temperature / the diameter of the thermal expansion microspheres before thermal expansion.

[0094] The obtained test data are recorded in Table 1 and Table 2 below:

[0095] Table 1 Test results of thermal expansion properties of each group of thermal expansion microspheres

[0096] Group Initial expansion temperature (℃) Maximum expansion temperature (℃) Example 1 group 53.6 147.4 Example 2 group 53.4 147.1 Example 3 group 53.9 147.6 Comparison group 1 62.7 141.8 Comparison of 2 groups 59.3 136.3

[0097] Table 2 Expansion ratio performance test results of each group of thermal expansion microspheres

[0098]

[0099]

[0100] By comparing and analyzing the relevant data in Table 1 and Table 2, it can be seen that the high expansion ratio heat-expandable microspheres prepared by the present invention not only have a low expansion temperature, but also have a wide expansion temperature range, and also have an excellent expansion ratio, effectively ensuring their quality. This shows that the high expansion ratio heat-expandable microspheres and the preparation method provided by the present invention have a broader market prospect and are more suitable for promotion.

[0101] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0102] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high expansion ratio thermal expansion microsphere, characterized in that: It is composed of the following raw materials in parts by weight: 10-15 parts of acrylonitrile, 12-15 parts of methyl methacrylate, 10-14 parts of butyl acrylate, 8-14 parts of hydroxyethyl methacrylate, 4-7 parts of foaming agent, 4-8 parts of dispersant, 3-6 parts of benzoyl peroxide, 2-3 parts of p-divinylbenzene, 2-3 parts of hydroquinone, 2-3 parts of sodium nitrate, 4-8 parts of polyvinylpyrrolidone and 30-40 parts of deionized water; The foaming agent is prepared by mixing the first base material and the second base material in a mass ratio of 1:0.2-0.3; The first base material is prepared by mixing n-pentane and isopentane in a mass ratio of 1:0.6-0.8; The preparation process of the second base material is as follows: The carbon nanospheres are placed in ultrapure water at a dosage of 0.01 to 0.04 g / mL and ultrasonically dispersed for 15 to 20 minutes to obtain a dispersion; Under the condition of a water bath at 1-5° C., the mixed acid is added dropwise to the obtained dispersion, and the mixture is stirred and mixed at 200-300 r / min. After the addition is completed, the temperature is raised to 70-78° C. and the stirring is continued for 180-200 min. The mixture is cooled to room temperature and centrifuged at 8000-10000 r / min for 10-15 min. The supernatant is discarded, and the mixture is washed with ultrapure water for 2-4 times, and then dried in a vacuum drying oven to constant weight to obtain modified carbon nanospheres; The modified carbon nanospheres, sodium carbonate powder, and concentrated sulfuric acid with a mass concentration of 97-98% are placed in anhydrous ethanol, magnetically stirred at room temperature for 10-15 minutes, naturally cooled to room temperature, and centrifuged at 7000-9000 r / min for 10-15 minutes. The supernatant is discarded, and the mixture is washed with anhydrous ethanol 2-4 times, and then dried in a vacuum drying oven to constant weight to obtain a second base material; The dispersant is prepared by mixing nano silicon dioxide and polyvinyl alcohol in a mass ratio of 1:0.3-0.

5.

2. The high expansion ratio thermal expansion microsphere according to claim 1, characterized in that: The mixed acid is prepared by mixing concentrated nitric acid with a mass concentration of 65-68% and concentrated sulfuric acid with a mass concentration of 97-98% in a volume ratio of 1:1.8-2.

8. The amount of the mixed acid added is 4.2-8.5% of the mass of the carbon nanospheres, and the addition time is 20-30 minutes.

3. The high expansion ratio thermal expansion microsphere according to claim 1, characterized in that: The added mass ratio of the modified carbon nanospheres, sodium carbonate powder and concentrated sulfuric acid with a mass concentration of 97-98% is 1:0.5-0.8:0.05-0.1, and the total mass of the modified carbon nanospheres, sodium carbonate powder and concentrated sulfuric acid with a mass concentration of 97-98% is 22-32% of the mass of anhydrous ethanol.

4. The method for preparing high-expansion-ratio thermally expandable microspheres according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: Accurately weigh acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, a dispersant, benzoyl peroxide, p-divinylbenzene, hydroquinone, sodium nitrate, polyvinyl pyrrolidone, and deionized water, and set aside; Step 2: placing the dispersant, polyvinyl pyrrolidone, hydroquinone and sodium nitrate in deionized water, stirring at 800-1000 rpm for 6-10 minutes to obtain an aqueous phase; Step 3: placing acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, benzoyl peroxide, and p-divinylbenzene in a mixing device, and stirring at 200-300 r / min for 10-12 minutes to obtain an oil phase substance; Step 4: Place the oil phase substance in the water phase substance, continue stirring at 800-1000 r / min for 5-8 minutes, then polymerize and stir under a nitrogen atmosphere at 0.4-0.5 MPa. After cooling to room temperature, filter, wash, and dry to obtain a finished product of high-expansion-ratio thermal expansion microspheres.

5. The method for preparing high expansion ratio thermal expansion microspheres according to claim 4, characterized in that: In step 4, the polymerization stirring speed is 380-400 r / min, the temperature is 68-72° C., and the time is 22-24 h.

6. The method for preparing high-expansion-ratio thermally expandable microspheres according to claim 4, wherein: In step 4, the washing is performed with deionized water for 2 to 4 times.

Images