High-airtightness expansion microsphere and preparation method thereof
By adding high-boiling-point compounds during the preparation of expanded microspheres, the problem of foaming agent leakage was solved, achieving a combination of high airtightness and good foaming performance, thus expanding the application range.
Patent Information
- Application Number
- CN202510914274.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-03
- Publication Date
- 2025-10-24
AI Technical Summary
Existing expandable microspheres are prone to foaming agent leakage during the foaming process, which leads to reduced expansion performance and affects application results.
One or more high-boiling-point compounds are added during the preparation of expanded microspheres. By keeping the high-boiling-point compounds in a liquid state in the inner shell of the microspheres during polymerization heating, the gaseous foaming agent is prevented from overflowing, thus improving air tightness.
It significantly improves the airtightness of expanded microspheres without affecting their foaming performance, thus broadening their application areas.
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Figure CN120829618A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of preparation of expanded microspheres, in particular to a kind of high air-tightness expanded microspheres and preparation method thereof. BACKGROUND
[0002] Expanded microspheres or thermal foaming microcapsules are a kind of temperature-driven volume expansion material. Expanded microspheres are divided into core and shell two-part structure, and the shell is composed of high molecular polymer, and the core component has the characteristic of being converted into gas after being heated. The industrial polymerization method of expandable microspheres is relatively single, mainly using suspension free radical copolymerization, which has long polymerization period and low polymerization efficiency. In addition, there are many factors affecting the performance of expandable microspheres, and each factor is mutually restricted, complex, which leads to the difficulty in synthesizing high-performance expandable microspheres.
[0003] Expanded microspheres are generally used as foaming materials in the fields of coatings, wallpapers, inks and the like, which can effectively reduce product density and save cost. In recent years, with the development of lightweight, low-cost and high-performance in the fields of automobiles, aerospace, electronics and electrical appliances, expanded microspheres are applied to the foaming processing of thermosetting resin, thermosetting elastomer, thermoplastic resin, rubber and thermoplastic elastomer, which gives the advantages of light weight, heat insulation, shock absorption, high specific strength and low price of foaming materials.
[0004] In the application of thermosetting resin and thermosetting elastomer, the initial foaming temperature of expanded microspheres is usually required to be lower than the curing temperature of resin, so low-boiling alkane (such as isobutane) is used as foaming agent. However, such small molecular alkane (especially C4 or less) is easy to leak when the shell of microsphere softens, which leads to the decrease of gas content and affects the expansion performance.
[0005] In summary, the problem of the decrease of expansion performance caused by the easy leakage of foaming agent in the current expanded microspheres still needs to be solved. SUMMARY
[0006] In view of the shortcomings of the prior art, one of the purposes of the present application is to provide a kind of high air-tightness expanded microspheres, which reduces the leakage of foaming agent when the microsphere expands by adding one or more high-boiling compounds at the same time as adding the foaming agent, improves the expansion ratio and reduces the risk of explosion when expanding.
[0007] To achieve this purpose, the present application adopts the following technical solutions:
[0008] A kind of preparation method of high air-tightness expanded microspheres, comprising the following steps: Step S1: mix monomer, initiator, crosslinking agent, volatile foaming agent and high-boiling compound to obtain oil phase; Step S2: mix water-based dispersion medium, inorganic salt, dispersant, dispersion stabilizing aid to obtain water phase; Step S3: stirring and dispersing the oil phase and the water phase to obtain a suspension solution; Step S4: polymerizing the obtained suspension solution in an inert atmosphere at 4080℃ under a pressure of 0.1-0.5 MPa for 15-25 hours, then reducing the temperature of the microsphere slurry to room temperature, filtering and drying to obtain high-airtightness expanded microspheres.
[0009] Further, the monomers used are one or more of acrylonitrile, methacrylonitrile, vinylidene chloride, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, butyl methacrylate, isobornyl methacrylate, ethyl methacrylate; preferably, the monomers are combined as 30-70wt% acrylonitrile, 0-20wt% methyl methacrylate, 30-70wt% vinylidene chloride; preferably, the monomers account for 60-80wt%, preferably 65-75wt% of the total weight of the expanded microspheres.
[0010] Further, the initiator used is one or more of azobisisobutyronitrile, azobisisoheptyl nitrile, benzoyl peroxide, lauryl peroxide, diisopropyl peroxydicarbonate, dicyclohexyl peroxydicarbonate; more preferably azobisisobutyronitrile; preferably, the initiator accounts for 0.1-5wt%, preferably 0.5-2wt% of the total weight of the expanded microspheres.
[0011] Further, the crosslinking agent is a multifunctional crosslinking agent containing carbon-carbon double bonds, preferably one or more of divinylbenzene, di(meth)acrylate ethylene glycol, di(meth)acrylate diethylene glycol, di(meth)acrylate triethylene glycol, di(meth)acrylate propylene glycol, di(meth)acrylate-1,4-butanediol, di(meth)acrylate-1,6-hexanediol, di(meth)acrylate glycerol, di(meth)acrylate-1,3-butanediol, di(meth)acrylate neopentyl glycol, di(meth)acrylate-1,10-decanediol, tri(meth)acrylate pentaerythritol, tetra(meth)acrylate pentaerythritol, hexa(meth)acrylate pentaerythritol, dimethylol tricyclodecane di(meth)acrylate, triallyl formaldehyde tri(meth)acrylate, allyl methacrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane triacrylate, di(meth)acrylate tributylene glycol, polyethylene glycol di(meth)acrylate, 3-acryloyloxy glycol monoacrylate, triacryloyl formaldehyde, triallyl isocyanate; preferably, the crosslinking agent is 0.1-1wt%, preferably 0.2-0.5wt% of the monomer combination.
[0012] Further, the foaming agent used is one or more of n-butane, isobutane, cyclohexane, isopentane and dichloromethane, more preferably isobutane; preferably, the low-boiling alkane accounts for 10-35wt%, preferably 15-25wt% of the total weight of the expanded microspheres.
[0013] Further, the high-boiling compound used is one or more of dibutyl phthalate, diisooctyl adipate, polydimethylsiloxane; preferably, the high-boiling compound accounts for 2-10wt%, preferably 5-8wt% of the total weight of the expanded microspheres.
[0014] Further, the dispersant includes one or more of colloidal silicon dioxide, colloidal calcium carbonate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, aluminum hydroxide sol, iron hydroxide, calcium sulfate, calcium oxalate, calcium carbonate, barium sulfate, barium carbonate, magnesium carbonate, active calcium phosphate, preferably colloidal silicon dioxide; preferably, the mass of the dispersant is 1-20 parts, preferably 5-10 parts, based on 100 parts of the mass of the water.
[0015] Further, the inorganic salt is a metal salt, preferably the inorganic salt includes one or more of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium sulfate, potassium sulfate, magnesium sulfate, sodium carbonate, potassium carbonate, sodium nitrate, potassium nitrate, more preferably sodium chloride and / or potassium chloride; preferably, the mass of the inorganic salt is 10-50 parts, preferably 15-35, based on 100 parts of the mass of the water.
[0016] Further, the dispersion stabilizing aid includes one or more of sodium nitrite, potassium nitrite, ferric chloride, sodium sulfide, potassium dichromate, cuprous chloride, copper acetate, titanium trichloride, ammonium thiocyanate, preferably sodium nitrite; preferably, the mass of the dispersion stabilizing aid is 1-5 parts, based on 100 parts of the mass of the water.
[0017] Another aspect of the present application provides a high-gas-tightness expanded microsphere prepared by the above method.
[0018] Use of a high-gas-tightness expanded microsphere, the microsphere being the above-mentioned expanded microsphere, or being prepared by the above-mentioned preparation method, the expanded microsphere and the foamed microsphere after expansion, for printing and dyeing, paint, ink, polyurethane polishing material, shoe sole, sound-absorbing material or thermal insulation material.
[0019] The present inventors have found that, in the synthesis of expanded microspheres, the addition of one or more high-boiling compounds, during the temperature rise of polymerization, prevents the gaseous foaming agent from overflowing due to the liquid state of the high-boiling compound in the inner shell of the expanded microspheres, which cannot reach the boiling point of the high-boiling compound, thereby improving the gas tightness of the expanded microspheres, and obtaining high-gas-tightness expanded microspheres.
[0020] Compared with the prior art, the present application has the following beneficial effects:
[0021] The prepared expanded microspheres have a significantly improved air tightness, meanwhile, the foaming performance of the expanded microspheres is not affected, and the application field of the expanded microspheres is widened.
[0022] The features of the present application can be clearly understood by referring to the drawings and the following detailed description of preferred embodiments. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 is a statistical chart of the results of the embodiment of the thermal expansion microspheres of the present application. DETAILED DESCRIPTION
[0024] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application is further described below in combination with specific drawings.
[0025] The main raw materials used in the embodiment are as follows:
[0026] Monomers: acrylonitrile (AN), Shanghai Aladdin Biochemical Technology Co., Ltd., reagent grade 99%; methyl methacrylate (MMA), Shanghai Aladdin Biochemical Technology Co., Ltd., reagent grade 99%; methyl acrylate (MA), Shanghai Aladdin Biochemical Technology Co., Ltd., reagent grade 99%; vinylidene chloride (VDC), Juhua Co., Ltd., VDC high-boiling substance 1,1-dichloroethane 630 ppm, 1,2-dichloroethylene 220 ppm, 1,1,2-trichloroethylene 90 ppm.
[0027] Foaming agent: n-butane, Aladdin Group Co., Ltd., reagent grade 99%; isobutane, Aladdin Group Co., Ltd., reagent grade 99%; isopentane, Aladdin Group Co., Ltd., reagent grade 99%; isooctane, Aladdin Group Co., Ltd., reagent grade 99%.
[0028] Crosslinking agent: ethylene glycol dimethacrylate (EGDMA), Shanghai Aladdin Biochemical Technology Co., Ltd., reagent grade 99%; 1,4-butanediol acrylate dimethyl ester (BDDA), Shanghai Aladdin Biochemical Technology Co., Ltd., reagent grade 99%.
[0029] Dispersant: magnesium hydroxide; colloidal silicon dioxide containing 25 mass% of silicon dioxide as an active ingredient, Shandong Kohl Silica Products Co., Ltd.
[0030] Co-dispersant: sodium chloride, Shenghai Chemical Co., Ltd., industrial grade 99%; polyvinylpyrrolidone, Shanghai Aladdin Biochemical Technology Co., Ltd., reagent grade 99%.
[0031] Initiator: lauryl peroxide, Shanghai Aladdin Bio-Chem Technology Co., Ltd., 99% reagent grade; azobisisobutyronitrile, Shanghai Aladdin Bio-Chem Technology Co., Ltd., 99% reagent grade.
[0032] Inhibitor: sodium nitrite, Shanghai Aladdin Bio-Chem Technology Co., Ltd., 99% reagent grade.
[0033] High boiling point compound: dibutyl phthalate, Jiangsu Raymon Chemical Technology Co., Ltd., 99% reagent grade; diisooctyl adipate, Jiangsu Raymon Chemical Technology Co., Ltd., 99% reagent grade; naphthenic oil KN4010, naphthenic oil KN4006, China Petroleum Karamay Petrochemical Company.
[0034] Example 1
[0035] 1. Preparation of water phase: 10000 g of deionized water was added to a 20 L polymerization kettle, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, stirring until the sodium chloride was completely dissolved and the silica was uniformly dispersed in the water to obtain the water phase;
[0036] 2. Preparation of oil phase: monomers (acrylonitrile 1600 g, methyl methacrylate 600 g, methacrylic acid 300 g), initiator (azobisisobutyronitrile 55 g, lauryl peroxide 5 g), crosslinking agent (1,4-butanediol dimethyl acrylate 100 g), foaming agent (isopentane 800 g, isooctane 100 g) and high boiling point compound (dibutyl phthalate 50 g) were added to a beaker and mixed under magnetic stirring.
[0037] 3. Mixing of water phase and oil phase: the homogenizer kettle was vacuumed, the oil phase was sucked into the homogenizer kettle, the homogenizer kettle was pressurized to 0.5 MPa with nitrogen, and the oil phase was dispersed in the water phase under mechanical stirring at 800 rpm for 30 min. The uniform suspension was transferred to a polymerization kettle with a 65 °C water bath, nitrogen was added to the polymerization kettle, the pressure was adjusted to 0.5 MPa, and the reaction was carried out under mechanical stirring at 200 rpm for 20 h. Next, the product was cooled to room temperature to obtain a microcapsule emulsion.
[0038] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter positive pressure filter, dried in a forced air oven at 50 °C for 10 h, and finally the agglomerates and larger particles were removed using a 120 mesh particle powder sieve to obtain the final physically expanded microspheres.
[0039] Comparative Example 1
[0040] The expanded microspheres were prepared according to the method of Example 1, except that in step 2, no high boiling point compound was added.
[0041] Example 2
[0042] 1. Preparation of the aqueous phase: 10000 g of deionized water was added to a 20 L polymerization kettle, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, stirring until the sodium chloride was completely dissolved, the silica was uniformly dispersed in the water, to obtain the aqueous phase;
[0043] 2. Preparation of the oil phase: monomers (acrylonitrile 1600 g, methyl methacrylate 500 g, methacrylic acid 400 g), initiator (azobisisobutyronitrile 50 g, lauroyl peroxide 10 g), crosslinking agent (1,4-butanediol acrylate dimethyl ester 100 g), foaming agent (isopentane 700 g, isooctane 200 g) and high-boiling compound (naphthenic oil (KN4010) 50 g) were added to a beaker and mixed under magnetic stirring.
[0044] 3. Mixing of the aqueous phase and the oil phase: the homogenizer kettle was evacuated, the oil phase was sucked into the homogenizer kettle, the homogenizer kettle was pressurized with nitrogen to 0.5 MPa, and the oil phase was dispersed in the aqueous phase by emulsification at 800 rpm mechanical stirring for 30 min. The uniform suspension was transferred to a polymerization kettle with a 65°C water bath, nitrogen was added to the polymerization kettle, the pressure was adjusted to 0.5 MPa, and the reaction was carried out under mechanical stirring at 200 rpm for 20 h. Next, the product was cooled to room temperature to obtain a microcapsule emulsion.
[0045] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter positive pressure filter, dried in a forced air oven at 50°C for 10 h, and finally, agglomerates and larger particles were removed using a 120 mesh granular powder sieve to obtain the final physically expanded microspheres.
[0046] Comparative Example 2
[0047] Expanded microspheres were prepared according to the method of Example 2, except that in Step 2, no high-boiling compound was added.
[0048] Example 3
[0049] 1. Preparation of the aqueous phase: 10000 g of deionized water was added to a 20 L polymerization kettle, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, stirring until the sodium chloride was completely dissolved, the silica was uniformly dispersed in the water, to obtain the aqueous phase;
[0050] 2. Preparation of the oil phase: monomers (acrylonitrile 1600 g, methyl methacrylate 400 g, methacrylic acid 500 g), initiator (azobisisobutyronitrile 45 g, lauroyl peroxide 15 g), crosslinking agent (1,4-butanediol acrylate dimethyl ester 100 g), foaming agent (isopentane 600 g, isooctane 300 g) and high-boiling compound (dibutyl phthalate 50 g) were added to a beaker and mixed under magnetic stirring.
[0051] 3. Mixing the aqueous and oil phases: Vacuum the homogenizer and draw the oil phase into the homogenizer. Nitrogen is then pressurized to 0.5 MPa and the mixture is emulsified for 30 minutes with mechanical stirring at 800 rpm to disperse the oil phase in the aqueous phase. The homogenized suspension is transferred to a polymerization reactor with a 65°C water bath. Nitrogen is added to the reactor, the pressure adjusted to 0.5 MPa, and the mixture is stirred at 200 rpm for 20 hours. The product is then cooled to room temperature to obtain a microcapsule emulsion.
[0052] 4. The microcapsule emulsion was washed and filtered using a 20-liter positive pressure filter, dried in a blast oven at 50°C for 10 h, and finally a 120-mesh granular powder sieve was used to remove agglomerates and larger particles to obtain the final physically expanded microspheres.
[0053] Comparative Example 3
[0054] Expanded microspheres were prepared according to the method of Example 3, except that in step 2, no high boiling point compound was added.
[0055] Example 4
[0056] 1. Preparation of the aqueous phase: To a 20 L polymerization kettle, add 10,000 g of deionized water, 1,000 g of silica containing 25% by mass as an active ingredient, 1 g of sodium nitrite, and 2,500 g of sodium chloride, and stir until the sodium chloride is completely dissolved and the silica is evenly dispersed in the water to obtain an aqueous phase.
[0057] 2. Preparation of oil phase: monomers (1600 g of acrylonitrile, 300 g of methyl methacrylate, 600 g of methacrylic acid), initiator (40 g of azobisisobutyronitrile, 10 g of lauroyl peroxide), crosslinking agent (100 g of ethylene glycol dimethacrylate), blowing agent (500 g of isopentane, 400 g of isooctane) and high boiling point compound (50 g of cyclohexane oil (KN4010)) were added to a beaker and mixed under magnetic stirring.
[0058] 3. Mixing the aqueous and oil phases: Vacuum the homogenizer and draw the oil phase into the homogenizer. Nitrogen is then pressurized to 0.5 MPa and the mixture is emulsified for 30 minutes with mechanical stirring at 800 rpm to disperse the oil phase in the aqueous phase. The homogenized suspension is transferred to a polymerization reactor with a 65°C water bath. Nitrogen is added to the reactor, the pressure adjusted to 0.5 MPa, and the mixture is stirred at 200 rpm for 20 hours. The product is then cooled to room temperature to obtain a microcapsule emulsion.
[0059] 4. The microcapsule emulsion was washed and filtered using a 20-liter positive pressure filter, dried in a blast oven at 50°C for 10 h, and finally a 120-mesh granular powder sieve was used to remove agglomerates and larger particles to obtain the final physically expanded microspheres.
[0060] Comparative Example 4
[0061] The expanded microspheres were prepared according to the method of Example 4, except that in Step 2, the high-boiling compound was not added.
[0062] Example 5
[0063] 1. Preparation of the aqueous phase: 10000 g of deionized water was added to a 20 L polymerization kettle, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, stirring until the sodium chloride was completely dissolved, and the silica was uniformly dispersed in the water, to obtain an aqueous phase;
[0064] 2. Preparation of the oil phase: the monomers (acrylonitrile 1600 g, methyl methacrylate 200 g, methacrylic acid 700 g), initiator (azobisisobutyronitrile 30 g, lauroyl peroxide 20 g), crosslinking agent (ethylene glycol dimethacrylate 100 g), foaming agent (isopentane 400 g, isooctane 500 g) and high-boiling compound (dibutyl phthalate 50 g) were added to a beaker and mixed under magnetic stirring.
[0065] 3. Mixing of the aqueous phase and the oil phase: the homogenizer kettle was evacuated, the oil phase was sucked into the homogenizer kettle, the homogenizer kettle was pressurized with nitrogen to 0.5 MPa, and the oil phase was dispersed in the aqueous phase by emulsification at 800 rpm mechanical stirring for 30 min. The uniform suspension was transferred to a polymerization kettle with a 65°C water bath, nitrogen was added to the polymerization kettle, the pressure was adjusted to 0.5 MPa, and the reaction was carried out under mechanical stirring at 200 rpm for 20 h. Next, the product was cooled to room temperature to obtain a microcapsule emulsion.
[0066] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter pressure filter, dried in a forced air oven at 50°C for 10 h, and finally, agglomerates and larger particles were removed using a 120 mesh particle powder sieve to obtain the final physical expanded microspheres.
[0067] Comparative Example 5
[0068] The expanded microspheres were prepared according to the method of Example 5, except that in Step 2, the high-boiling compound was not added.
[0069] Example 6
[0070] 1. Preparation of the aqueous phase: 10000 g of deionized water was added to a 20 L polymerization kettle, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, stirring until the sodium chloride was completely dissolved, and the silica was uniformly dispersed in the water, to obtain an aqueous phase;
[0071] 2. Oil phase preparation: Monomers (acrylonitrile 1600 g, methyl methacrylate 600 g, methyl acrylate 300 g), initiator (azobisisobutyronitrile 55 g, lauryl peroxide 5 g), crosslinking agent (1,4-butanediol dimethacrylate 100 g), foaming agent (isopentane 800 g, isooctane 100 g) and high-boiling compound (naphthenic oil (KN4010) 50 g) were added to a beaker and mixed under magnetic stirring.
[0072] 3. Mixing of water phase and oil phase: The homogenizer was evacuated, the oil phase was sucked into the homogenizer, the homogenizer was pressurized with nitrogen to 0.5 MPa, and the oil phase was dispersed in the water phase by emulsification under mechanical stirring at 800 rpm for 30 min. The homogeneous suspension was transferred to a polymerization kettle with a water bath at 65°C, nitrogen was introduced into the polymerization kettle, the pressure was adjusted to 0.5 MPa, and the reaction was carried out under mechanical stirring at 200 rpm for 20 h. Next, the product was cooled to room temperature to obtain a microcapsule emulsion.
[0073] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter pressure filter, dried in a forced air oven at 50°C for 10 h, and finally deagglomerated and larger particles were removed using a 120 mesh granular powder sieve to obtain the final physically expanded microspheres.
[0074] Comparative Example 6
[0075] Expanded microspheres were prepared according to the method of Example 6, except that in Step 2, no high-boiling compound was added.
[0076] Example 7
[0077] 1. Water phase preparation: Deionized water 10000 g, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, was added to a 20 L polymerization kettle, stirred until the sodium chloride was completely dissolved and the silica was uniformly dispersed in the water to obtain a water phase;
[0078] 2. Oil phase preparation: Monomers (acrylonitrile 1600 g, methyl methacrylate 500 g, methyl acrylate 400 g), initiator (azobisisobutyronitrile 50 g, lauryl peroxide 10 g), crosslinking agent (1,4-butanediol dimethacrylate 100 g), foaming agent (isopentane 700 g, isooctane 200 g) and high-boiling compound (dibutyl phthalate 50 g) were added to a beaker and mixed under magnetic stirring.
[0079] 3. Mixing of water phase and oil phase: The homogenizer was evacuated, the oil phase was sucked into the homogenizer, and the homogenizer was pressurized with nitrogen gas to 0.5 MPa. The oil phase was dispersed in the water phase by emulsification at 800 rpm for 30 min under mechanical stirring. The uniform suspension was transferred to a polymerization kettle with a water bath at 65°C, nitrogen gas was added to the polymerization kettle, the pressure was adjusted to 0.5 MPa, and the reaction was performed for 20 h under mechanical stirring at 200 rpm. Next, the product was cooled to room temperature to obtain a microcapsule emulsion.
[0080] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter pressure filter, dried using a forced air oven at 50°C for 10 h, and finally, agglomerates and larger particles were removed using a 120 mesh granular powder sieve to obtain the final physically expanded microspheres.
[0081] Comparative Example 7
[0082] Expanded microspheres were prepared according to the method of Example 7, except that in Step 2, the high-boiling compound was not added.
[0083] Example 8
[0084] 1. Preparation of water phase: Deionized water 10000 g was added to a 20 L polymerization kettle, and 1000 g of silica having a content of 25 mass% as an active ingredient, 1 g of sodium nitrite, and 2500 g of sodium chloride were added. The mixture was stirred until the sodium chloride was completely dissolved and the silica was uniformly dispersed in the water to obtain a water phase.
[0085] 2. Preparation of oil phase: Monomers (acrylonitrile 1600 g, methyl methacrylate 400 g, methyl acrylate 500 g), an initiator (azobisisobutyronitrile 45 g, lauroyl peroxide 15 g), a crosslinking agent (1,4-butanediol dimethacrylate 100 g), a blowing agent (isopentane 600 g, isooctane 300 g), and a high-boiling compound (naphthenic oil (KN4010) 50 g) were added to a beaker and mixed under magnetic stirring.
[0086] 3. Mixing of water phase and oil phase: The homogenizer was evacuated, the oil phase was sucked into the homogenizer, and the homogenizer was pressurized with nitrogen gas to 0.5 MPa. The oil phase was dispersed in the water phase by emulsification at 800 rpm for 30 min under mechanical stirring. The uniform suspension was transferred to a polymerization kettle with a water bath at 65°C, nitrogen gas was added to the polymerization kettle, the pressure was adjusted to 0.5 MPa, and the reaction was performed for 20 h under mechanical stirring at 200 rpm. Next, the product was cooled to room temperature to obtain a microcapsule emulsion.
[0087] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter pressure filter, dried using a forced air oven at 50°C for 10 h, and finally, agglomerates and larger particles were removed using a 120 mesh granular powder sieve to obtain the final physically expanded microspheres.
[0088] Comparative Example 8
[0089] The expanded microspheres were prepared according to the method of Example 8, except that in Step 2, the high-boiling compound was not added.
[0090] Example 9
[0091] 1. Preparation of the aqueous phase: 10000 g of deionized water was added to a 20 L polymerization kettle, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, stirring until the sodium chloride was completely dissolved, and the silica was uniformly dispersed in the water, to obtain an aqueous phase;
[0092] 2. Preparation of the oil phase: the monomers (acrylonitrile 1600 g, methyl methacrylate 300 g, methyl acrylate 600 g), the initiator (azobisisobutyronitrile 40 g, lauroyl peroxide 10 g), the crosslinking agent (ethylene glycol dimethacrylate 100 g), the foaming agent (isopentane 500 g, isooctane 400 g), and the high-boiling compound (dibutyl phthalate 50 g) were added to a beaker and mixed under magnetic stirring.
[0093] 3. Mixing of the aqueous phase and the oil phase: the homogenizer kettle was evacuated, the oil phase was sucked into the homogenizer kettle, the homogenizer kettle was pressurized with nitrogen to 0.5 MPa, and the oil phase was dispersed in the aqueous phase by emulsification at 800 rpm mechanical stirring for 30 min. The uniform suspension was transferred to a polymerization kettle with a 65°C water bath, nitrogen was added to the polymerization kettle, the pressure was adjusted to 0.5 MPa, and the reaction was carried out under mechanical stirring at 200 rpm for 20 h. Next, the product was cooled to room temperature to obtain a microcapsule emulsion.
[0094] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter pressure filter, dried in a forced air oven at 50°C for 10 h, and finally, agglomerates and larger particles were removed using a 120 mesh particle powder sieve to obtain the final physical expanded microspheres.
[0095] Comparative Example 9
[0096] The expanded microspheres were prepared according to the method of Example 9, except that in Step 2, the high-boiling compound was not added.
[0097] Example 10
[0098] 1. Preparation of the aqueous phase: 10000 g of deionized water was added to a 20 L polymerization kettle, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, stirring until the sodium chloride was completely dissolved, and the silica was uniformly dispersed in the water, to obtain an aqueous phase;
[0099] 2. Oil phase preparation: Monomers (acrylonitrile 1600 g, methyl methacrylate 200 g, methacrylic acid 700 g), initiator (azobisisobutyronitrile 30 g, lauryl peroxide 20 g), crosslinking agent (ethylene glycol dimethacrylate 100 g), foaming agent (isopentane 400 g, isooctane 500 g) and high-boiling compound (naphthenic oil (KN4010) 50 g) were added to a beaker and mixed under magnetic stirring.
[0100] 3. Mixing of water phase and oil phase: The homogenizer was evacuated, the oil phase was sucked into the homogenizer, the homogenizer was pressurized with nitrogen to 0.5 MPa, and the oil phase was dispersed in the water phase by emulsification under mechanical stirring at 800 rpm for 30 min. The homogeneous suspension was transferred to a polymerization kettle with a water bath at 65°C, nitrogen was introduced into the polymerization kettle, the pressure was adjusted to 0.5 MPa, and the reaction was carried out under mechanical stirring at 200 rpm for 20 h. Next, the product was cooled to room temperature to obtain a microcapsule emulsion.
[0101] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter pressure filter, dried in a forced air oven at 50°C for 10 h, and finally deagglomerated and larger particles were removed using a 120 mesh granular powder sieve to obtain the final physically expanded microspheres.
[0102] Comparative Example 10
[0103] Expanded microspheres were prepared according to the method of Example 10, except that in Step 2, no high-boiling compound was added.
[0104] Example 11
[0105] 1. Water phase preparation: Deionized water 10000 g, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, was added to a 20 L polymerization kettle, and stirred until the sodium chloride was completely dissolved and the silica was uniformly dispersed in the water to obtain a water phase;
[0106] 2. Oil phase preparation: Monomers (acrylonitrile 1600 g, methyl methacrylate 600 g, vinylidene chloride 300 g), initiator (azobisisobutyronitrile 55 g, lauryl peroxide 5 g), crosslinking agent (1,4-butanediol acrylate dimethyl ester 100 g), foaming agent (isopentane 800 g, isooctane 100 g) and high-boiling compound (dibutyl phthalate 50 g) were added to a beaker and mixed under magnetic stirring.
[0107] 3. Mixing of water phase and oil phase: The homogenizer tank was evacuated, the oil phase was sucked into the homogenizer tank, the homogenizer tank was pressurized with nitrogen to 0.5 MPa, and the oil phase was dispersed in the water phase by emulsification at 800 rpm mechanical stirring for 30 min. The uniform suspension was transferred to the polymerization tank with a water bath at 65°C, nitrogen was added to the polymerization tank, the pressure was adjusted to 0.5 MPa, and the reaction was carried out at 200 rpm mechanical stirring for 20 h. Next, the product was cooled to room temperature to obtain the microcapsule emulsion.
[0108] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter positive pressure filter, dried at 50°C for 10 h using a forced air oven, and finally agglomerates and larger particles were removed using a 120 mesh granular powder sieve to obtain the final physically expanded microspheres.
[0109] Comparative Example 11
[0110] Expanded microspheres were prepared according to the method of Example 11, except that in Step 2, the high-boiling compound was not added.
[0111] Example 12
[0112] 1. Water phase preparation: Deionized water 10000 g was added to a 20 L polymerization tank, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, and stirred until the sodium chloride was completely dissolved and the silica was uniformly dispersed in the water to obtain the water phase;
[0113] 2. Oil phase preparation: The monomers (acrylonitrile 1600 g, methyl methacrylate 500 g, vinylidene chloride 400 g), initiator (azo-bis-isobutyronitrile 50 g, lauryl peroxide 10 g), crosslinking agent (1,4-butanediol dimethacrylate 100 g), foaming agent (isopentane 700 g, isooctane 200 g), and high-boiling compound (naphthenic oil (KN4010) 50 g) were added to a beaker and mixed with magnetic stirring.
[0114] 3. Mixing of water phase and oil phase: The homogenizer tank was evacuated, the oil phase was sucked into the homogenizer tank, the homogenizer tank was pressurized with nitrogen to 0.5 MPa, and the oil phase was dispersed in the water phase by emulsification at 800 rpm mechanical stirring for 30 min. The uniform suspension was transferred to the polymerization tank with a water bath at 65°C, nitrogen was added to the polymerization tank, the pressure was adjusted to 0.5 MPa, and the reaction was carried out at 200 rpm mechanical stirring for 20 h. Next, the product was cooled to room temperature to obtain the microcapsule emulsion.
[0115] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter positive pressure filter, dried at 50°C for 10 h using a forced air oven, and finally agglomerates and larger particles were removed using a 120 mesh granular powder sieve to obtain the final physically expanded microspheres.
[0116] Comparative Example 12
[0117] Expanded microspheres were prepared according to the method of Example 12, except that in step 2, no high boiling point compound was added.
[0118] Example 13
[0119] 1. Preparation of the aqueous phase: To a 20 L polymerization kettle, add 10,000 g of deionized water, 1,000 g of silica containing 25% by mass as an active ingredient, 1 g of sodium nitrite, and 2,500 g of sodium chloride, and stir until the sodium chloride is completely dissolved and the silica is evenly dispersed in the water to obtain an aqueous phase.
[0120] 2. Preparation of oil phase: Add monomers (1600 g of acrylonitrile, 400 g of methyl methacrylate, 500 g of vinylidene chloride), initiator (45 g of azobisisobutyronitrile, 15 g of lauroyl peroxide), crosslinker (100 g of 1,4-butanediol dimethyl acrylate), foaming agent (600 g of isopentane, 300 g of isooctane) and high boiling point compound (50 g of dibutyl phthalate) into a beaker and mix under magnetic stirring.
[0121] 3. Mixing the aqueous and oil phases: Vacuum the homogenizer and draw the oil phase into the homogenizer. Nitrogen is then pressurized to 0.5 MPa and the mixture is emulsified for 30 minutes with mechanical stirring at 800 rpm to disperse the oil phase in the aqueous phase. The homogenized suspension is transferred to a polymerization reactor with a 65°C water bath. Nitrogen is added to the reactor, the pressure adjusted to 0.5 MPa, and the mixture is stirred at 200 rpm for 20 hours. The product is then cooled to room temperature to obtain a microcapsule emulsion.
[0122] 4. The microcapsule emulsion was washed and filtered using a 20-liter positive pressure filter, dried in a blast oven at 50°C for 10 h, and finally a 120-mesh granular powder sieve was used to remove agglomerates and larger particles to obtain the final physically expanded microspheres.
[0123] Comparative Example 13
[0124] Expanded microspheres were prepared according to the method of Example 13, except that in step 2, no high boiling point compound was added.
[0125] Example 14
[0126] 1. Preparation of the aqueous phase: To a 20 L polymerization kettle, add 10,000 g of deionized water, 1,000 g of silica containing 25% by mass as an active ingredient, 1 g of sodium nitrite, and 2,500 g of sodium chloride, and stir until the sodium chloride is completely dissolved and the silica is evenly dispersed in the water to obtain an aqueous phase.
[0127] 2. Oil phase preparation: Monomers (acrylonitrile 1600 g, methyl methacrylate 300 g, vinylidene chloride 600 g), initiator (azobisisobutyronitrile 40 g, lauryl peroxide 10 g), crosslinking agent (ethylene glycol dimethacrylate 100 g), foaming agent (isopentane 500 g, isooctane 400 g) and high-boiling compound (naphthenic oil (KN4010) 50 g) were added to a beaker and mixed under magnetic stirring.
[0128] 3. Mixing of water phase and oil phase: The homogenizer was evacuated, the oil phase was sucked into the homogenizer, the homogenizer was pressurized with nitrogen to 0.5 MPa, and the oil phase was dispersed in the water phase by emulsification under mechanical stirring at 800 rpm for 30 min. The homogeneous suspension was transferred to a polymerization kettle with a water bath at 65°C, nitrogen was introduced into the polymerization kettle, the pressure was adjusted to 0.5 MPa, and the reaction was carried out under mechanical stirring at 200 rpm for 20 h. Next, the product was cooled to room temperature to obtain a microcapsule emulsion.
[0129] 4. The microcapsule emulsion was washed and pressure-filtered using a 20 liter pressure filter, dried in a forced air oven at 50°C for 10 h, and finally deagglomerated and larger particles were removed using a 120 mesh granular powder sieve to obtain the final physically expanded microspheres.
[0130] Comparative Example 14
[0131] Expanded microspheres were prepared according to the method of Example 14, except that in Step 2, no high-boiling compound was added.
[0132] Example 15
[0133] 1. Water phase preparation: Deionized water 10000 g, containing 25 mass% of silica as an active ingredient: 1000 g, sodium nitrite: 1 g; sodium chloride: 2500 g, were added to a 20 L polymerization kettle, and stirred until the sodium chloride was completely dissolved and the silica was uniformly dispersed in the water to obtain a water phase;
[0134] 2. Oil phase preparation: Monomers (acrylonitrile 1600 g, methyl methacrylate 200 g, vinylidene chloride 700 g), initiator (azobisisobutyronitrile 30 g, lauryl peroxide 20 g), crosslinking agent (ethylene glycol dimethacrylate 100 g), foaming agent (isopentane 400 g, isooctane 500 g) and high-boiling compound (dibutyl phthalate 50 g) were added to a beaker and mixed under magnetic stirring.
[0135] 3. Mix the water phase and oil phase: evacuate the homogenizer, suck the oil phase into the homogenizer, pressurize the homogenizer with nitrogen to 0.5 MPa, emulsify for 30 min under mechanical stirring at 800 rpm to disperse the oil phase in the water phase. Transfer the uniform suspension into the polymerization kettle with a water bath at 65 °C, add nitrogen into the polymerization kettle, adjust the pressure to 0.5 MPa, and react for 20 h under mechanical stirring at 200 rpm. Next, cool the product to room temperature to obtain the microcapsule emulsion.
[0136] 4. Wash the microcapsule emulsion by pressure filtration using a 20 liter pressure filter, dry for 10 h using a forced air oven at 50 °C, and finally remove agglomerates and larger particles using a 120 mesh particle powder sieve to obtain the final physically expanded microspheres.
[0137] Comparative Example 15
[0138] Prepare the expanded microspheres according to the method of Example 15, except that in Step 2, do not add the high boiling point compound.
[0139] Compare the examples, comparative examples
[0140] Test instruments:
[0141] Discovery TGA 55 thermal gravimetric analyzer produced by TA Instruments, USA; sample 1.00 mg, test method: record the weight loss change with the temperature rising at a rate of 10 °C / min to 380 °C.
[0142] BT-9300S laser particle size distribution instrument, disperse for 10 min at 1600 rpm, and record the average particle size.
[0143] Conclusion: After adding the high boiling point compounds dibutyl phthalate or naphthenic oil KN4010, it can be found that the speed of the blowing agent leakage is significantly slower and the leakage temperature is also shifted to a higher temperature. Table 1 Examples and Comparative Examples 1-4 Table 2 Examples and Comparative Examples 5-8 Table 3 Examples and Comparative Examples 9-12 Table 4 Examples and Comparative Examples 13-15 The above shows and describes the basic principles and main features of the present application and the advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of the present application is defined by the appended claims and their equivalents.
Claims
1. A process for the preparation of high gas-tight expanded microspheres, characterized in that, The method comprises the following steps: Step S1: mixing monomers, initiators, cross-linking agents, volatile blowing agents and high-boiling compounds to obtain an oil phase; Step S2: mixing an aqueous dispersion medium, inorganic salts, dispersants and dispersion stabilizing aids to obtain an aqueous phase; Step S3: stirring and dispersing the oil phase and the aqueous phase to obtain a suspension solution; Step S4: after the suspension solution is polymerized at 40-80℃ under a pressure of 0.1-0.5 MPa for 15-25 hours in an inert atmosphere, the temperature of the microsphere slurry is reduced to room temperature, and the microspheres are filtered and dried to obtain high-gas-tightness expanded microspheres.
2. The method of claim 1, wherein the high-gas-barrier expanded microspheres are prepared by the steps of: The high-boiling compound is one or more of dibutyl phthalate, diisooctyl adipate and polydimethylsiloxane; the high-boiling compound accounts for 2-10 wt% of the total weight of the expanded microspheres.
3. The method of claim 2, wherein the high-gas-barrier expanded microspheres are prepared by the steps of: The monomer is one or more of acrylonitrile, methacrylonitrile, vinylidene dichloride, methyl acrylate, ethyl acrylate, butyl acrylate, isooctyl acrylate, methyl methacrylate, butyl methacrylate, isobornyl methacrylate and ethyl methacrylate.
4. The method of claim 3, wherein the high-gas-barrier expanded microspheres are prepared by the steps of: The combination of the monomers is 30-70 wt% acrylonitrile, 0-20 wt% methyl methacrylate and 30-70 wt% vinylidene dichloride.
5. The method of claim 4, wherein the high-gas-barrier expanded microspheres are prepared by the steps of: The monomers account for 60-80 wt% of the total weight of the expanded microspheres.
6. The method of claim 2, wherein the high-gas-barrier expanded microspheres are prepared by the steps of: The initiator is one or more of azobisisobutyronitrile, azobisisoheptyl nitrile, benzoyl peroxide, lauroyl peroxide, diisopropyl peroxydicarbonate and dicyclohexyl peroxydicarbonate.
7. The method of claim 6, wherein the high-gas-barrier expanded microspheres are prepared by the steps of: The initiator accounts for 0.1-5 wt% of the total weight of the expanded microspheres.
8. The method of claim 2, wherein the high-gas-barrier expanded microspheres are prepared by the steps of: The cross-linking agent is a multi-function cross-linking agent containing a carbon-carbon double bond.
9. The method of claim 8, wherein the high-gas-barrier expanded microspheres are prepared by the steps of: The cross-linking agent is one or more of divinylbenzene, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, glycerol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol hexa(meth)acrylate, dimethylol tricyclodecane di(meth)acrylate, triallyl formaldehyde tri(meth)acrylate, allyl methacrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane triacrylate, tributylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 3-acryloyloxy ethylene glycol monoacrylate, triacryloyl formaldehyde, triallyl isocyanate.
10. The method of claim 2, wherein the high-gas-barrier expanded microspheres are prepared by the steps of: The volatile blowing agent is one or more of n-butane, isobutane, cyclohexane, isopentane and dichloromethane.
11. The method of claim 10, wherein the high-gas-barrier expanded microspheres are prepared by the steps of: The volatile blowing agent accounts for 10-35 wt% of the total weight of the expanded microspheres.
12. The method for preparing high-air-tightness expanded microspheres according to claim 2, characterized in that: The inorganic salt is one or more of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium sulfate, potassium sulfate, magnesium sulfate, sodium carbonate, potassium carbonate, sodium nitrate, and potassium nitrate.
13. The method for preparing high-air-tightness expanded microspheres according to claim 12, characterized in that: The mass of the inorganic salt is 15-35 parts based on 100 parts of the mass of the water.
14. The method for preparing high-air-tightness expanded microspheres according to claim 2, characterized in that: The dispersant includes one or more of colloidal silicon dioxide, colloidal calcium carbonate, magnesium hydroxide, calcium hydroxide, aluminum hydroxide, aluminum hydroxide sol, iron hydroxide, calcium sulfate, calcium oxalate, calcium carbonate, barium sulfate, barium carbonate, magnesium carbonate, and active calcium phosphate.
15. The method for preparing high-air-tightness expanded microspheres according to claim 14, characterized in that: The mass of the dispersant is 1-20 parts based on 100 parts of the mass of the water.
16. The method for preparing high-air-tightness expanded microspheres according to claim 2, characterized in that: The dispersion stabilizing aid includes one or more of sodium nitrite, potassium nitrite, ferric chloride, sodium sulfide, potassium dichromate, cuprous chloride, copper acetate, titanium trichloride, and ammonium thiocyanate.
17. The method for preparing high-air-tightness expanded microspheres according to claim 16, characterized in that: The mass of the dispersion stabilizing aid is 1-5 parts based on 100 parts of the mass of the water.
18. A high-gas-barrier expanded microsphere, characterized by, It is prepared by the method of any one of claims 1-17.