Thermal expansion microsphere with high foaming rate and preparation method thereof

Abstract

The invention relates to the technical field of polymer microspheres, in particular to a high-foaming-ratio thermal expansion microsphere and a preparation method thereof. The thermal expansion microspheres with the high foaming rate are prepared from 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 methylacrylate, 4 to 7 parts of a foaming agent, 4 to 8 parts of a dispersing agent, 3 to 6 parts of benzoyl peroxide, 2 to 3 parts of p-divinyl benzene, 2 to 3 parts of hydroquinone, 2 to 3 parts of sodium nitrate, 4 to 8 parts of polyvinylpyrrolidone and 30 to 40 parts of deionized water. The high-foaming-rate thermal expansion microspheres prepared by the preparation method disclosed by the invention not only have lower expansion temperature, but also have a wider expansion temperature interval and excellent expansion rate, and the quality of the microspheres is effectively ensured.

Description

Technical Field

[0001] The 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 generally composed of hydrocarbons and the shell is a thermoplastic polymer. When heated to a certain temperature, the internal hydrocarbons vaporize to generate pressure, causing the volume of the microspheres to expand rapidly, thereby showing unique thermal expansion properties. With this characteristic, thermally expandable microspheres are widely used in many fields. For example, adding thermally expandable microspheres to coatings can prepare coatings with functions such as heat insulation; using them in plastic products can achieve lightweighting and improve cushioning performance; in the papermaking industry, they are used to give paper a special texture and touch, etc.

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

[0004] Based on this, the present invention provides a high foaming ratio heat-expandable 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 foaming ratio heat-expandable microsphere and a preparation method thereof. The prepared high foaming ratio heat-expandable microsphere not only has a lower expansion temperature, but also has a wider expansion temperature range, and also has an excellent expansion ratio, which effectively guarantees 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 foaming ratio heat-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 foaming agent, 4 to 8 parts of 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 selected from n-pentane and isopentane mixed 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 ratio of 0.01 to 0.04 g / mL and subjected to ultrasonic dispersion treatment for 15 to 20 minutes to obtain a dispersion;

[0012] Under the condition of 1-5° C. in a water bath, a 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 treatment is continued for 180-200 min, and the mixture is cooled to room temperature, and the mixture is 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, washed with anhydrous ethanol for 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 dripping amount of the mixed acid is 4.2-8.5% of the mass of the carbon nanospheres, and the dripping 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: also provides a method for preparing the above-mentioned high expansion ratio heat-expandable microspheres, comprising the following steps:

[0018] Step 1, accurately weigh acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, foaming agent, dispersant, benzoyl peroxide, p-divinylbenzene, hydroquinone, sodium nitrate, polyvinyl pyrrolidone and deionized water for use;

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

[0020] Step 3, placing acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, benzoyl peroxide and p-divinylbenzene in a mixing device, stirring at 200 to 300 r / min for 10 to 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 min, then polymerize and stir under a nitrogen atmosphere at 0.4-0.5 MPa, cool to room temperature, filter, wash, and dry to obtain a finished product of high foaming 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 with deionized water for 2 to 4 times.

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

[0025] In the present invention, acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, foaming agent, dispersant, benzoyl peroxide, p-divinylbenzene, hydroquinone, sodium nitrate, polyvinyl pyrrolidone and deionized water are used as raw materials, dispersant, polyvinyl pyrrolidone, hydroquinone and sodium nitrate are placed in deionized water and stirred to obtain water phase material, then acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, foaming agent, benzoyl peroxide and p-divinylbenzene are placed in a mixing device and stirred to obtain oil phase material, finally the oil phase material is placed in the water phase material and continues to stir, and under the condition of nitrogen atmosphere, polymerization and stirring are performed, after cooling to room temperature, suction filtration, washing and drying are performed 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, which effectively guarantees its quality and quality. The high foaming ratio heat-expandable microspheres and the preparation method thereof provided by the present invention have broader market prospects 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 described embodiments 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 creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] The present embodiment provides a high foaming ratio heat-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 foaming agent, 4 parts of 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 for ultrasonic dispersion treatment at a dosage of 0.01 g / mL 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 the mixture was 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, and the mixture was cooled to room temperature. The mixture was centrifuged at 8000 r / min for 10 min, the supernatant was discarded, and 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, washed twice with anhydrous ethanol, and then placed in a vacuum drying oven 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 the nano-silicon dioxide was purchased from Wuhan Kemik Biomedical Technology Co., Ltd.

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

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

[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 min 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 was 380 r / min, the temperature was 68° C., and the time was 22 h.

[0046] The washing was performed 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 embodiment 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 foaming ratio heat-expandable 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 treatment for 17 min to obtain a dispersion liquid;

[0054] In a water bath at 3°C, the mixed acid was added dropwise to the obtained dispersion, and the mixture was 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, cooled to room temperature, and centrifuged at 9000 r / min for 12 min. The supernatant was discarded, washed with ultrapure water for 3 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, washed with anhydrous ethanol for 3 times, and then placed in a vacuum drying oven 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 a mixture of nano silicon dioxide and polyvinyl alcohol in a mass ratio of 1:0.4.

[0060] In this embodiment, it should be noted that the nano-silicon dioxide was purchased from Wuhan Kemik Biomedical Technology Co., Ltd.

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

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

[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 was 390 r / min, the temperature was 70° C., and the time was 23 h.

[0067] Washing was done 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 embodiment 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 foaming 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 a mixture of normal 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 are placed in ultrapure water at a dosage ratio of 0.01 to 0.04 g / mL and subjected to ultrasonic dispersion treatment for 20 minutes to obtain a dispersion liquid;

[0075] In a water bath at 5°C, the mixed acid was added dropwise to the obtained dispersion, and the mixture was 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, cooled to room temperature, and centrifuged at 10000 r / min for 15 min. The supernatant was discarded, and the mixture was washed with ultrapure water for 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, washed with anhydrous ethanol for 4 times, and then placed in a vacuum drying oven 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 the nano-silicon dioxide was purchased from Wuhan Kemik Biomedical Technology Co., Ltd.

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

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

[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 foaming 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] The 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 to replace 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 lower expansion temperature, but also have a wider expansion temperature range, and also have excellent expansion ratio, which effectively guarantees its quality. This shows that the high expansion ratio heat-expandable microspheres and the preparation method thereof provided by the present invention have a broader market prospect and are more suitable for promotion.

[0101] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0102] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high expansion ratio heat-expandable 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 polyvinyl pyrrolidone and 30-40 parts of deionized water.

2. The high expansion ratio heat-expandable microsphere according to claim 1, characterized in that: 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.

3. The high expansion ratio heat-expandable microsphere according to claim 2, characterized in that: The first base material is prepared by mixing n-pentane and isopentane in a mass ratio of 1:0.6-0.

8.

4. The high expansion ratio heat-expandable microsphere according to claim 2, characterized in that: The preparation process of the second base material is as follows: The carbon nanospheres are placed in ultrapure water at a dosage ratio of 0.01 to 0.04 g / mL and subjected to ultrasonic dispersion treatment for 15 to 20 minutes to obtain a dispersion; Under the condition of 1-5° C. in a water bath, a 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 treatment is continued for 180-200 min, and the mixture is cooled to room temperature, and the mixture is 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, centrifuged at 7000-9000 r / min for 10-15 minutes, the supernatant is discarded, washed with anhydrous ethanol for 2-4 times, and then placed in a vacuum drying oven to dry to constant weight to obtain a second base material.

5. The high expansion ratio heat-expandable microsphere according to claim 4, 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.

6. The high expansion ratio heat-expandable microsphere according to claim 4, 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.

7. The high expansion ratio heat-expandable microsphere according to claim 1, characterized in that: The dispersant is prepared by mixing nano silicon dioxide and polyvinyl alcohol in a mass ratio of 1:0.3-0.

5.

8. A method for preparing high expansion ratio heat-expandable microspheres according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step 1, accurately weigh acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, foaming agent, dispersant, benzoyl peroxide, p-divinylbenzene, hydroquinone, sodium nitrate, polyvinyl pyrrolidone and deionized water for use; Step 2: placing the dispersant, polyvinyl pyrrolidone, hydroquinone and sodium nitrate in deionized water, stirring at 800-1000 r / min for 6-10 minutes to obtain an aqueous phase material; Step 3, placing acrylonitrile, methyl methacrylate, butyl acrylate, hydroxyethyl methacrylate, a foaming agent, benzoyl peroxide and p-divinylbenzene in a mixing device, stirring at 200 to 300 r / min for 10 to 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 min, then polymerize and stir under a nitrogen atmosphere at 0.4-0.5 MPa, cool to room temperature, filter, wash, and dry to obtain a finished product of high foaming ratio thermal expansion microspheres.

9. The method for preparing high foaming ratio heat-expandable microspheres according to claim 8, 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.

10. The method for preparing high foaming ratio heat-expandable microspheres according to claim 8, characterized in that: In step 4, the washing is performed with deionized water for 2 to 4 times.

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