CN115532187A - Preparation method of expandable microspheres for improving dry powder agglomeration - Google Patents
Preparation method of expandable microspheres for improving dry powder agglomeration Download PDFInfo
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- CN115532187A CN115532187A CN202211108229.8A CN202211108229A CN115532187A CN 115532187 A CN115532187 A CN 115532187A CN 202211108229 A CN202211108229 A CN 202211108229A CN 115532187 A CN115532187 A CN 115532187A
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- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
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Abstract
The invention provides a preparation method of expandable microspheres for improving dry powder agglomeration, which comprises the steps of mixing monomers, an initiator, a cross-linking agent, a volatile foaming agent, an auxiliary agent and the like to obtain an oil phase; mixing an aqueous dispersion medium, inorganic salt, a dispersion stabilizer and a dispersion stabilizing auxiliary agent to obtain a water phase; stirring the oil phase and the water phase to disperse the oil phase and the water phase to obtain a suspension solution; the dry powder agglomeration is improved by adding the treating agent and the auxiliary agent for re-reaction after the preparation of the expandable microspheres by a suspension polymerization method is finished. The expandable microspheres with improved dry powder agglomeration provided by the invention can be used in various applications, such as various plastics, elastomers, plasticine, paper/paperboard and the like, and the specific applications comprise: PVC plastics, SBS elastomers, ultralight clay, braille paper, light cement, hollow ceramics, emulsion explosives and the like.
Description
Technical Field
The invention relates to the field of high polymer materials, in particular to a preparation method of expandable microspheres for improving dry powder agglomeration.
Technical Field
The expandable microspheres are microspheres with a core-shell structure, wherein the shells of the microspheres are thermoplastic polymers, and expandable substances such as volatile expanding agents of aliphatic hydrocarbon and the like are encapsulated in the shells. The expandable microspheres as a light filler are successfully applied to the fields of plasticine, printing paste, plastics, elastomers and the like. However, the expandable microspheres are easy to agglomerate after being dried after being prepared, and finally, the dispersibility of the microspheres in application is not ideal.
In the presently disclosed patents, there are few solutions to the dry powder agglomeration of microspheres themselves.
Disclosure of Invention
The invention aims to provide a preparation method of expandable microspheres for improving dry powder agglomeration, which overcomes the defects in the prior art.
The invention provides a preparation method of expandable microspheres for improving dry powder agglomeration, which comprises the steps of mixing a monomer, an initiator, a cross-linking agent, a volatile foaming agent, an auxiliary agent and the like to obtain an oil phase; mixing an aqueous dispersion medium, inorganic salt, a dispersion stabilizer and a dispersion stabilizing auxiliary agent to obtain a water phase; stirring the oil phase and the water phase to disperse the oil phase and the water phase to obtain a suspension solution; dry powder agglomeration is improved by adding a treating agent and an auxiliary agent thereof for re-reaction after the preparation of the expandable microspheres by a suspension polymerization method is finished.
A preparation method of expandable microspheres for improving dry powder agglomeration comprises the following steps:
(1) Mixing a monomer, an initiator, a cross-linking agent and a volatile expanding agent to obtain an oil phase;
(2) Mixing an aqueous dispersion medium, inorganic salt, a dispersion stabilizer and a dispersion stabilizing auxiliary agent to obtain a water phase;
(3) Stirring the oil phase and the water phase to disperse the oil phase and the water phase to obtain a suspension solution;
(4) And (2) carrying out polymerization reaction on the obtained suspension solution at 40-80 ℃ and under the pressure of 0.1-0.5 MPa in an inert atmosphere for 15-25 hours, adding a treating agent and an auxiliary agent thereof, continuing the reaction for 4-6 hours, filtering and drying to obtain the expandable microspheres with improved dry powder agglomeration.
Further, the treating agent is a silane coupling agent.
Furthermore, the silane coupling agent is one or more of vinyltriethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane, gamma-mercaptopropyltriethoxysilane and vinyltriethoxysilane.
Furthermore, the auxiliary agent is an acid substance which is one or more of hydrochloric acid, nitric acid and sulfuric acid.
Further, the expandable microspheres comprise a thermoplastic shell and a volatile expanding agent encapsulated in the thermoplastic shell.
Further, the monomer comprises the following components in parts by weight:
nitrile monomer 40-90 parts
0 to 60 parts of acrylic monomer
5-50 parts of acrylate monomers.
Further, the nitrile monomer is one or more of acrylonitrile, methacrylonitrile, alpha-chloroacrylonitrile, alpha-ethoxyacrylonitrile or fumaronitrile; the acrylic monomer is one or more of acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, alpha-methyl cinnamic acid maleic acid, itaconic acid, fumaric acid and citraconic acid; the acrylate monomer is one or more of methyl acrylate, ethyl acrylate, butyl acrylate, dicyclopentenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate or isobornyl methacrylate.
Further, the boiling point of the volatile expanding agent is not higher than the softening temperature of the thermoplastic shell, and the volatile expanding agent is C4-C12 aliphatic hydrocarbon compounds.
Preferably, the volatile expanding agent is a C4-C8 linear or branched saturated hydrocarbon compound.
Furthermore, the volatile expanding agent is one or more of low molecular weight hydrocarbons such as isooctane, isopentane, isobutane, neopentane, n-hexane, heptane, petroleum ether and the like, tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane and trimethyl-n-propylsilane.
Preferably, the volatile expanding agent is one or more of isooctane, isopentane, isobutane, n-hexane and petroleum ether.
Preferably, based on the total weight of the nitrile monomer and the acrylic ester monomer: the thermoplastic shell also comprises the following components in percentage by weight:
0.1 to 5 weight percent of cross-linking agent
1-5 wt% of initiator
0.1 to 0.5 percent of dispersion stabilizer
0.1 to 0.5 percent of dispersion stabilizing additive
1 to 3 percent of inorganic salt.
Further, the crosslinking agent is one or more of divinylbenzene, ethylene glycol di (meth) acrylate, di (ethylene 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, glycerin 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, dipentaerythritol hexa (meth) acrylate, triallylformal tri (meth) acrylate, allyl methacrylate, trimethylolpropane tri (meth) acrylate, tributylene glycol di (meth) acrylate, PEG #200 di (meth) acrylate, PEG #400 di (meth) acrylate, PEG #600 di (meth) acrylate, 3-acryloxydiol monoacrylate, triacylglycol, triallyl isocyanate, triallyl isocyanurate, divinyl ether, divinyl vinyl ether, diethylene glycol ether, triethylene glycol di (meth) ether, tetraethylene glycol ether; the initiator is one or more of dicetyl peroxydicarbonate, bis (4-tert-butylcyclohexyl) peroxydicarbonate, dioctanoate peroxide, di- (2-ethylhexyl) peroxydicarbonate, dibenzoate peroxide, dilaurate peroxide, didecanoic acid peroxide, tert-butyl peracetate, tert-butyl peroxylaurate, tert-butyl peroxybenzoate, tert-butyl hydroperoxide, cumene ethylperoxide, diisopropylhydroxydicarboxylate, 2 '-azobis ((2, 4-dimethylvaleronitrile), 2' -azobis (isobutyronitrile), 1 '-azobis (cyclohexane-1-carbonitrile), dimethyl 2, -azobis (2-methylpropionate), or 2,2' -azobis [ 2-methyl-N- (2-hydroxyethyl) -propionamide ]; the dispersion stabilizer is one or more of colloidal silicon dioxide, colloidal clay, calcium carbonate, calcium phosphate, calcium sulfate, calcium oxalate or barium carbonate, and the dispersion stabilizing auxiliary agent is one or more of methylcellulose, methyl hydroxypropyl cellulose, polyvinyl alcohol, gelatin, polyvinylpyrrolidone, polyethylene oxide, dialkyl dimethyl ammonium chloride, alkyl trimethyl ammonium chloride, alkyl sodium sulfate, alkyl sodium sulfonate, alkyl dimethyl amino acetic acid betaine or alkyl dihydroxy ethyl amino acetic acid betaine.
Preferably, the thermoplastic shell is suspension polymerized in an aqueous dispersion medium containing a dispersion stabilizer and/or a dispersion stabilizing aid, the aqueous dispersion medium is water, and inorganic salts can be added, and the inorganic salts are sodium chloride and sodium sulfate.
The expandable microspheres with improved dry powder agglomeration provided by the invention can be used in various applications, such as various plastics, elastomers, plasticine, paper/paperboard and the like, and the specific applications comprise: PVC plastics, SBS elastomers, ultralight clay, braille paper, light cement, hollow ceramics, emulsion explosives and the like.
The inventor finds that in the expandable microspheres, by introducing the treating agent and the auxiliary agent thereof after the polymerization reaction is finished, groups generated after the treating agent is hydrolyzed under certain temperature and auxiliary agent conditions can be subjected to chemical reaction with silicon hydroxyl on the surfaces of the microspheres, the silicon hydroxyl can be effectively killed, and finally the expandable microspheres improved by dry powder agglomeration are obtained. The beneficial effects of the invention are:
the agglomeration of the dry powder is obviously improved, the foaming performance of the expandable microspheres is not influenced, and the application field of the expandable microspheres is widened.
Drawings
Fig. 1 is a schematic diagram of the structure of expandable microspheres with improved dry powder agglomeration.
FIG. 2 is a topographical view of expandable microspheres prepared in the blank example.
FIG. 3 is a topographical view of expandable microspheres prepared in example 1.
FIG. 4 is a topographical view of expandable microspheres prepared in example 2.
FIG. 5 is a topographical view of expandable microspheres prepared in example 3.
FIG. 6 is a topographical view of expandable microspheres prepared in example 4.
FIG. 7 is a topographical view of expandable microspheres prepared in example 5.
FIG. 8 is a topographical view of expandable microspheres prepared in example 6.
Detailed Description
Referring to fig. 1, a thermoplastic shell 1 and a volatile expansion agent 2 encased in said thermoplastic shell 1.
The invention is further illustrated by the following examples. In the examples listed, all parts and percentages in the examples refer to parts and percentages by weight unless otherwise indicated, and the analysis of the thermally expandable microspheres was carried out using the following methods and apparatus:
(1) Analysis of particle size distribution characteristics:
the particle size distribution of the microspheres was measured by a particle size distribution laser diffraction analyzer LS13320 manufactured by Bekman coulter corporation, and the average diameter was measured as the volume average particle size;
(2) Analysis of foaming characteristics:
the properties of the thermally expandable microspheres were measured by a thermomechanical analyzer TMA Q-400 manufactured by TA Instrument Co. Samples were prepared from 1.0mg of thermally expandable microspheres contained in aluminum pans of 6.7mm diameter and 4.5mm depth. The aluminum pan was then sealed with an aluminum pan of 6.5mm diameter and 4.0mm depth. The sample temperature was raised from ambient to 280 ℃ at a ramp rate of 20 ℃/min depending on the TMA extension probe type, and a force of 0.1N was applied by the probe. The analysis is performed by measuring the vertical displacement of the probe;
-initial temperature of expansion (Tstart): temperature (. Degree. C.) at which probe displacement starts to increase
Maximum foaming temperature (Tmax): temperature at which probe displacement reaches maximum (. Degree. C.)
-foaming density (Dmin): ratio of microsphere addition to foamed volume (kg/m) 3 ）
(3) The evaluation method of the dry powder agglomeration comprises the following steps: the experimental instrument is a biological microscope, namely an Oumeck particle image processor of Zhuhai Oumeck instruments, inc., the model is PIP8.1, and observation and analysis of the dry powder are carried out by 10 times of magnification.
After the reaction is finished, 100 g of slurry is taken, and a filter cake after suction filtration is placed in an oven and dried for 16 hours at the set temperature of 50 ℃. Grinding after drying, and sieving with 150 mesh sieve. The sieved dry powder was subjected to morphology and TMA analysis. We will compare the blank examples with examples 1 to 6.
Preparation example of blank expandable microspheres
Water phase:
280 g water (aqueous dispersion medium)
10g sodium chloride (inorganic salt)
0.5 g aqueous silica solution (dispersion stabilizer) having a concentration of 50 wt%
0.5 g a 5% strength by weight aqueous solution of methylhydroxypropylcellulose (average molecular weight 26000 g/mol) (dispersion stabilizing assistant)
0.2g sodium lauryl sulfate (Dispersion stabilizing aid)
Oil phase:
135 g acrylonitrile (monomer)
60g methacrylic acid (monomer)
40g of methyl methacrylate (monomer)
4g benzoyl peroxide (initiator)
0.6g trimethylolpropane tri (meth) acrylate (crosslinker)
50g isopentane (volatile expanding agent)
The oil phase and the aqueous phase were dispersed by stirring with a homomixer at 7000rpm for 2 minutes to prepare a suspension solution. The suspension was immediately injected into a 1 liter high pressure reactor, air was replaced by nitrogen, and the reactor was pressurized to an initial pressure of 0.3 MPa. Then, the polymerization was carried out at 50 to 70 ℃ for 20 hours. After polymerization, basic expandable microspheres are obtained by filtering, washing and drying, and the related properties of the microspheres are shown in table 1.
TABLE 1
In Table 1, (nitrile monomer) AN acrylonitrile, (acrylate monomer) MAA methacrylic acid, methyl methacrylate, TMPDMA trimethylolpropane trimethacrylate, BPO benzoyl peroxide, IP: isopentane.
Example 1
Preparation of blank examples 12 g of gamma- (methacryloyloxy) propyltrimethoxysilane were added after the reaction was complete and reacted at 50 ℃ for 6 hours. The resulting product was filtered and dried to obtain expandable microspheres with improved dry powder agglomeration, as listed in table 2.
Example 2
Preparation of blank examples after the end of the reaction 12 g of gamma- (methacryloyloxy) propyltrimethoxysilane and 6g of dilute hydrochloric acid (10% by mass) were added and reacted at 50 ℃ for 6 hours. The resulting product was filtered and dried to obtain expandable microspheres with improved dry powder agglomeration, as listed in table 2.
Example 3
Preparation of blank example after the end of the reaction, 12 g of vinyltriethoxysilane and 6g of dilute hydrochloric acid (10% by mass) were added and reacted at 50 ℃ for 6 hours. The resulting product was filtered and dried to obtain expandable microspheres with improved dry powder agglomeration, as listed in table 2.
Example 4
Preparation of blank example after the end of the reaction, 6g of vinyltriethoxysilane and 6g of dilute hydrochloric acid (10% by mass) were added and reacted at 50 ℃ for 6 hours. The resulting product was filtered and dried to obtain expandable microspheres with improved dry powder agglomeration, as listed in table 2.
Example 5
Preparation examples 18 g of vinyltriethoxysilane and 6g of dilute hydrochloric acid (10% by mass) were added to the oil phase composition and reacted at 50 ℃ for 6 hours. The resulting product was filtered and dried to obtain expandable microspheres with improved dry powder agglomeration, as listed in table 2.
Example 6
Preparation examples 12 g of vinyltriethoxysilane and 12 g of dilute hydrochloric acid (10% by mass) were added to the oil phase composition to react at 50 ℃ for 6 hours. The resulting product was filtered and dried to obtain expandable microspheres with improved dry powder agglomeration, as listed in table 2.
From the data of Table 2-1 we first found: after the treatment agent is added and reacted for 6 hours, the expansion performance of the microspheres is not greatly influenced.
We can find from the data of figures 2-8 that: after the polymerization reaction is finished and the treating agent is added for reaction at a certain temperature, the hydrolysate of the treating agent can possibly react with silicon hydroxyl on the surface of the microsphere, and the dry powder agglomeration phenomenon of the microsphere is obviously improved; in addition, the hydrochloric acid added as an auxiliary agent has the influence on the hydrolysis of the treating agent and the reaction of a hydrolysate and silicon hydroxyl, and the addition amount of the hydrochloric acid has an optimal value, so that the dry powder agglomeration is improved under a certain amount of conditions.
We can also find from the data of figures 2-8: the treating agents with different structures have no need of improving the dry powder agglomeration, the vinyltriethoxysilane with relatively short chain length or small molecular weight may have relatively high effective functional group content, and the killing effect on the silicon hydroxyl on the surface of the microsphere is relatively good, so that the improvement effect on the dry powder agglomeration is relatively good.
We can also find from the data of figures 2-8 that: when other conditions are fixed, after the treating agent and the auxiliary agent are added, three reactions including hydrolysis reaction of the treating agent, reaction of the treating agent and silicon hydroxyl on the surface of the microsphere and reaction between hydrolysis products of the treating agent may exist in a reaction system, and when the addition amount of the treating agent is large, the reaction generated by hydrolysis of the treating agent is enhanced, so that the killing effect on the silicon hydroxyl on the surface of the microsphere is weakened, and therefore, the addition amount of the treating agent also has an optimal value.
TABLE 2-1
Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions. Therefore, the protection scope of the present invention is not limited to the disclosed embodiments, and any suitable changes or modifications thereof by those skilled in the art should be considered as not departing from the scope of the present invention.
Claims (6)
1. A preparation method of expandable microspheres for improving dry powder agglomeration is characterized by comprising the following steps:
(1) Mixing a monomer, an initiator, a cross-linking agent and a volatile expanding agent to obtain an oil phase;
(2) Mixing an aqueous dispersion medium, inorganic salt, a dispersion stabilizer and a dispersion stabilizing auxiliary agent to obtain a water phase;
(3) Stirring the oil phase and the water phase to disperse the oil phase and the water phase to obtain a suspension solution;
(4) And (3) carrying out polymerization reaction on the obtained suspension solution for 15 to 25 hours at the temperature of 40-80 ℃ and under the pressure of 0.1 to 0.5MPa in an inert atmosphere, adding a treating agent and an auxiliary agent thereof, continuing the reaction for 4 to 6 hours, filtering and drying to obtain the expandable microspheres with improved dry powder agglomeration.
2. The method of making expandable microspheres for improved dry powder agglomeration according to claim 1, wherein the treating agent is a silane coupling agent.
3. The method for preparing expandable microspheres for improving dry powder agglomeration according to claim 2, wherein the silane coupling agent comprises one or more of vinyltriethoxysilane, gamma- (methacryloyloxy) propyltrimethoxysilane, gamma-mercaptopropyltriethoxysilane, and vinyltriethoxysilane.
4. The method for preparing expandable microspheres for improving dry powder agglomeration according to claim 1, wherein the auxiliary agent is an acid substance selected from one or more of hydrochloric acid, nitric acid and sulfuric acid.
5. The method of claim 1 wherein said expandable microspheres comprise a thermoplastic shell and a volatile expansion agent encapsulated within said thermoplastic shell.
6. The method for preparing expandable microspheres for improving dry powder agglomeration according to claim 1, wherein the monomer comprises the following components in parts by weight:
nitrile monomer 40-90 parts
0 to 60 parts of acrylic monomer
5-50 parts of acrylate monomers.
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