CN1583860A - Preparing method for high cross-linked olefinic polymer/calcium carbonate composite nanometer particle - Google Patents

Abstract

The invention discloses a preparation method of highly cross-linked olefin polymer/calcium carbonate composite nanoparticles, which belongs to the field of polymer materials. The method uses nanometer CaCO ₃ particles with lipophilic surface, olefin monomer and cross-linking agent as raw materials, and carries out emulsion polymerization with water as dispersion medium in the presence of emulsifier and initiator. Among them, the percentage by weight of olefin monomer, CaCO ₃ particles, cross-linking agent, emulsifier and initiator is: olefin monomer: 54.5-97.8%, CaCO ₃ particles: 1-25%, cross-linking agent: 0.1- 15%, emulsifier: 1-5%, initiator: 0.1-0.5%, the nano-particles prepared by the present invention have the structural characteristics of using nano- _CaCO3 particles as the core and organic olefin cross-linked polymer as the shell. Spherical or ellipsoidal, narrow particle size distribution and less than 100 nanometers, and highly cross-linked.

Description

A preparation method of highly cross-linked olefin polymer/calcium carbonate composite nanoparticles

technical field

The invention relates to a preparation method of highly cross-linked olefin polymer/calcium carbonate (CaCO ₃ ) composite nanoparticles, which belongs to the field of polymer materials.

Background technique

Due to its low price and various excellent properties, nano-CaCO ₃ is widely used as a filler in plastics, rubber, coatings, inks and other fields. However, due to its high surface energy, the particles are easy to agglomerate; and the surface is alkaline and has a certain polarity, and its affinity with the organic matrix is not good, so its use in the organic phase is greatly limited. It is usually necessary to modify its surface to improve its dispersion and compatibility in organic matrices. Commonly used low-molecular modifiers are stearic acid, in addition to acrylic acid, condensed phosphoric acid, etc. The modification mechanism is to use acids to react with Ca ⁺ on the surface of CaCO ₃ particles to form salt deposition or coating on the surface of CaCO ₃ particles thereby changing its surface properties. In addition to acid substances, coupling agents are also commonly used modifiers. For example, the surface of CaCO ₃ is treated with a titanate coupling agent, and then polystyrene is coated on the surface, and the polymer and CaCO are reinforced by the coupling agent. ₃ The interface effect of the surface. Coating a layer of polymer on the surface of _CaCO3 , on the one hand, can make the hydrophilic surface become lipophilic; on the other hand, in the application of filled polymers, the physical entanglement between polymer chains can effectively strengthen the filler and The compatibility and interfacial strength between the matrix and thus is an important modification method.

There are currently two main methods for preparing polymer/inorganic composite nanoparticles, namely coating method and grafting method. Among them, the coating method is to select the prepared polymer through physical effects such as solvation, or to select certain monomers through chemical reactions such as polymerization to form a polymer coating layer on the surface of inorganic nanoparticles, but this method Because there is no chemical bond between the polymer layer and the surface of the inorganic particles, it is easy to fall off under the action of the solvent or under the shearing action of mechanical force; and the grafting method is to select the surface with energy and inorganic particles, or the energy and introduction in the inorganic The polymer or monomer reacted by the functional group on the surface of the particle is grafted on the surface of the inorganic nanoparticle to form a polymer coating layer by the reaction of the functional group or by a polymerization reaction. The polymer layer and the inorganic There are strong chemical bonds between the particle surfaces, so the coating layer is not easy to fall off. In the past, most of the literature work on the preparation of polymer/CaCO ₃ composite particles by the emulsion method was aimed at micron or submicron CaCO ₃ particles, and the coating ratio was generally less than 100%, and the final polymer coated on the surface of CaCO ₃ The non-extractable part of the extract generally does not exceed 20%.

Except for the above-mentioned coating method and grafting method, cross-linked polymer/CaCO ₃ composite particles are very rare. In fact, using a cross-linking agent to obtain a firm coating is another important method besides the grafting method, and it is different from the grafting method in that it can solve the problem of using simple grafting or simple coating microspheres. Collapse problem when hollow ball. Chinese patent CN1351896 utilizes _CaCO3 as a solid pore-forming agent, cooperates with a liquid pore-forming agent, mixes them with monomers, cross-linking agents, and initiators to prepare microspheres through suspension polymerization, and then extracts them with ethanol, soaks them in acid, and dries them. and other steps to prepare porous separation media.

Contents of the invention

The purpose of the present invention is to provide a kind of preparation method of highly cross-linked olefin polymer/ _CaCO Composite nanoparticle, the nanoparticle prepared by this method has nano- _CaCO3 particle as core, with organic olefin cross-network polymerization The substance is a structural feature of a shell, with a spherical or ellipsoidal shape, a narrow particle size distribution and less than 100 nanometers, and a high degree of cross-linking.

The preparation method of highly cross-linked olefin polymer/ _CaCO3 composite nanoparticles of the present invention is to use _CaCO3 particles, olefin monomers, and crosslinking agents as raw materials, and realize it by emulsion polymerization in the presence of emulsifiers and initiators. It is characterized in that the diameter of the _CaCO3 particles is less than 100nm and has an lipophilic surface, and the olefin monomer is a monoolefin substance containing a carbon-carbon unsaturated double bond in the molecule, which can be styrene, vinyl chloride , any one or more of acrylonitrile, acrylate, methacrylate, the crosslinking agent can be a substance containing more than one polymerizable ethylenically unsaturated bond in the molecule and at least one Any of the coupling agents of carbon-carbon unsaturated double bonds, substances containing more than one polymerizable vinyl unsaturated bond in the molecule can be 1,3-butadiene, 2-methyl-1,3- Butadiene, 2,3-dimethyl-1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, divinylbenzene, divinylnaphthalene, ethylene glycol Diacrylate, Ethylene Glycol Dimethacrylate, Allyl Acrylate, Trimethylolpropane Triacrylate, Trimethylolpropane Trimethacrylate, Triallyl Isocyanurate, Any one or more of polybutadiene, divinylsilane compounds, diallylsilane compounds, and low molecular weight organopolysiloxanes containing at least two vinyl groups in the molecule, and at least one carbon in the molecule The coupling agent for unsaturated double bonds can be any one or more of silane type, aluminate type, borate type, titanate type coupling agent, and the emulsifier is cationic and nonionic Type emulsifier compound system, cationic emulsifier can be dodecyl ammonium chloride, dodecyl ammonium acetate, cetyl trimethyl ammonium bromide, cetyl trimethyl ammonium chloride , cetyl pyridinium bromide, any one or more, the non-ionic emulsifier can be C _3-10 alkylphenol polyoxyethylene (4-50) ether, C _2-18 fatty alcohol polyoxygen Any of ethylene (4-50) ether, polyoxyethylene (4-50) sorbitan mono C _11-18 fatty acid ester, polyoxyethylene (4-50) sorbitan tri-C _11-18 fatty acid ester or several, the initiator is a substance that can have a dissociation energy of 105 to 150 kJ/mol at 40 to 95°C and can generate free radicals to cause the polymerization of olefin monomers. The substance can be potassium persulfate, persulfuric acid Any one of ammonium, azobisisobutyronitrile, azobisisoheptanonitrile, and dibenzoyl peroxide. The polymerization method is emulsion polymerization with water as the dispersion medium. During polymerization, olefin monomers, CaCO ₃ The weight percentage of each component of particle, linking agent, emulsifier, initiator is:

Olefin monomer: 54.5～97.8%

CaCO ₃ particles: 1 to 25%

Crosslinking agent: 0.1～15%

Emulsifier: 1~5%

Initiator: 0.1～0.5%

Concrete preparation steps of the present invention are as follows:

(1) _CaCO3 particles are added to the olefin monomer to mix and disperse evenly;

(2) Add the above-mentioned mixture into a reactor containing deionized water, emulsifier and initiator and pre-heated to 40°C, and make it warm up to a temperature range of 70-95°C for 0.5-10 hours;

(3) The crosslinking agent can be added to the reactor together with the olefin monomer in step (1), or it can be added by a continuous method or a semi-continuous method after the reaction starts, and the present invention preferably selects a one-step method;

(4) After cooling and discharging, the highly cross-linked olefin polymer/ _CaCO3 composite nanoparticles in the emulsion state can be obtained, and the emulsion can also be demulsified, washed, and dried to obtain highly cross-linked particles in the powder state. Type Olefin Polymer/CaCO ₃ Composite Nanoparticles.

Compared with the prior art, the present invention has some advantages and outstanding effects: a highly cross-linked olefin polymer/CaCO ₃ composite nanoparticle proposed by the present invention has a total reaction yield of about 80%, and cannot be extracted The amount of polymer is about 90%, which is higher than the reports in relevant literature or patents that can be seen so far. After the preparation is completed, it can be kept in the emulsion state, or it can be dried and kept in the powder state, but no matter what state it is kept in, its composite nanoparticles will have nano-CaCO ₃ particles as the core and organic olefin cross-linked network. The polymer is the structural feature of the shell, with spherical or ellipsoidal shape, narrow particle size distribution and less than 100 nanometers, and highly cross-linked features, which can be used directly or further prepared into hollow spherical nanoparticles for use. This method can not only solve the problems of low grafting rate and low grafting efficiency in the preparation of simple grafted nanoparticles, but also fundamentally overcome the easy coating layer that existed in the use of simple coated nanoparticles in the past. The problems of shedding, poor heat resistance, solvent resistance and easy aggregation between particles can be solved. More importantly, it can solve the problem of collapse when preparing hollow spherical nanoparticles by using simple grafted or simple coated nanoparticles, etc. . The preparation is simple and easy to realize industrial production. The cross-linked composite nanoparticles can be stably kept in the state of emulsion, and can also be dried into a powder state, which is easy to store and use. It has great potential in the future development of nanomaterial science and technology Wide range of uses.

Description of drawings

Figure 1 is the electron microscope image of polystyrene/CaCO ₃ cross-linked composite nanoparticles

Detailed ways:

Example 1: Add 60ml of deionized water, 0.5g of cetyltrimethylammonium bromide and 0.1g of nonylphenol polyoxyethylene to a four-necked flask equipped with mechanical stirring, reflux condenser, nitrogen protection and thermometer (10) Ether, be warming up to 40 ℃, after stirring and dissolving, add 2g average particle diameter and have lipophilic surface _CaCO Particle and 15ml styrene monomer, 0.68g trimethylol propane trimethacrylate ( TMPTMA), 0.1 g of azobisisobutyronitrile, heated up to 80° C., reacted for 1 to 2 hours, then raised to 90° C., continued to react for 0.5 to 1 hour, and cooled to discharge. Part of the emulsion after the discharge is demulsified, washed and dried to obtain a white powdery product. The total reaction yield is calculated to be 76%. After the dried composite nanoparticles are extracted with xylene for 12 hours, it is measured that it cannot The amount of polymer extracted was 99%. It can be seen from the electron microscope photo of composite nanoparticles in Figure 1 that the particle size is mainly distributed in the range of 50-70nm. In addition, after immersing the cross-linked composite nanoparticles with excess dilute hydrochloric acid for 24 hours, the _CaCO3 core was removed without changing the appearance of the particles, and hollow nanoparticles were obtained, which could maintain the original dispersed shape and granularity. path.

Embodiment 2: add 60ml deionized water, 0.07g ammonium persulfate, 0.5g cetyltrimethylammonium bromide and 0.1g Nonylphenol polyoxyethylene (10) ether, warming up to 40°C, stirring and dissolving, adding 2g of CaCO with an average particle diameter of 40nm and _15ml of styrene monomer mixture, raising the temperature to 80°C, After reacting for 1-2 hours, the temperature was raised to 90° C., the reaction was continued for 0.5-1 hour, and the material was cooled and discharged. Part of the emulsion after discharge was demulsified, washed, and dried to obtain a white powder product. The total reaction yield was calculated to be 74%. After the dried composite nanoparticles were extracted with xylene for 12 hours, it was measured that they could not be extracted. The amount of polymer extracted was 96%. In addition, after immersing the cross-linked composite nanoparticles with excess dilute hydrochloric acid for 24 hours, the _CaCO3 core was removed without changing the appearance of the particles, and hollow nanoparticles were obtained, which could maintain the original dispersed shape and granularity. path.

Embodiment 3: The preparation method is the same as that of Example 1, except that styrene is changed into methyl methacrylate. The results obtained are shown in Table 1.

Embodiment 4: The preparation method is the same as that of Example 1, except that TMPTMA is replaced by divinylbenzene. The results obtained are shown in Table 1.

Example 5: The preparation method is the same as in Example 1, except that TMPTMA is replaced by γ-methacryloxypropyltrimethoxysilane. The results obtained are shown in Table 1.

Embodiment 6: The preparation method is the same as that of Embodiment 1, except that TMPTMA is replaced by vinyltriethoxysilane. The results obtained are shown in Table 1.

Embodiment 7: The preparation method is the same as that of Embodiment 1, and the addition amount of TMPTMA is reduced from 0.68g to 0.14g. The results obtained are shown in Table 1.

Embodiment 8: The preparation method is the same as that of Embodiment 1, and the addition amount of TMPTMA is increased from 0.68g to 0.95g. The results obtained are shown in Table 1.

Embodiment 9: The preparation method is the same as that in Example 1, and the amount of CaCO added is increased from 2.0 _g to 4.0 g. The results obtained are shown in Table 1.

Embodiment 10: The preparation method is the same as in Example 1, and the _amount of CaCO is reduced from 2.0 g to 1.0 g. The results obtained are shown in Table 1.

Example 11: The preparation method is the same as in Example 1, and the amount of cetyltrimethylammonium bromide is increased from 0.5 g to 0.75 g. The results obtained are shown in Table 1.

Example 12: The preparation method is the same as in Example 1, except that cetyltrimethylammonium bromide is changed to cetyltrimethylammonium chloride. The results obtained are shown in Table 1.

Example 13: The preparation method is the same as in Example 1, except that nonylphenol polyoxyethylene (10) ether is replaced by octylphenol polyoxyethylene (20) ether. The results obtained are shown in Table 1.

Table 1 Preparation data of olefin polymer/CaCO ₃ crosslinked composite nanoparticles Example Polymerization yield% Non-extractable polymer % Example 1 76 99 Example 2 74 96 Example 3 88 87 Example 4 89 86 Example 5 82 94 Example 6 80 90 Example 7 79 94 Example 8 74 95 Example 9 75 83 Example 10 80 97 Example 11 78 96 Example 12 77 94 Example 13 76 95

Claims (1)

1, a kind of preparation method of highly cross-linked type olefin polymer/calcium carbonate composite nanoparticle, this method is to be raw material with calcium carbonate particle, olefin monomer, linking agent, under the condition that emulsifier, initiator exist, Realized by emulsion polymerization, it is characterized in that described calcium carbonate particle diameter is less than 100nm and has lipophilic surface; Described olefin monomer is the single olefin material that contains a carbon-carbon unsaturated double bond in the molecule, can be Any one or more of styrene, vinyl chloride, acrylonitrile, acrylate, and methacrylate; the crosslinking agent can be a substance containing more than one polymerizable ethylenically unsaturated bond in the molecule and Any of the coupling agents containing at least one carbon-carbon unsaturated double bond in the molecule, and substances containing more than one polymerizable vinyl unsaturated bond in the molecule can be 1,3-butadiene, 2-methyl -1,3-butadiene, 2,3-dimethyl-1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, divinylbenzene, divinyl Naphthalene, Ethylene Glycol Diacrylate, Ethylene Glycol Dimethacrylate, Allyl Acrylate, Trimethylolpropane Triacrylate, Trimethylolpropane Trimethacrylate, Triallyl Isotriacrylate Any one or more of polycyanate, polybutadiene, divinylsilane compound, diallylsilane compound, and low-molecular-weight organopolysiloxane containing at least two vinyl groups in the molecule. The coupling agent containing at least one carbon-carbon unsaturated double bond can be any one or more of silane-type, aluminate-type, borate-type, titanate-type coupling agents; the emulsifier is A compound system of cationic and non-ionic emulsifiers, cationic emulsifiers can be dodecyl ammonium chloride, dodecyl ammonium acetate, cetyltrimethylammonium bromide, cetyltrimethylammonium Any one or more of methyl ammonium chloride, cetyl pyridinium bromide, non-ionic emulsifier can be C _3~10 alkylphenol polyoxyethylene (4~50) ether, C _{2~ 18} fatty alcohol polyoxyethylene (4-50) ether, polyoxyethylene (4-50) sorbitan mono C _11-18 fatty acid ester, polyoxyethylene (4-50) sorbitan tri-C _11-18 fatty acid ester Any one or more of them; the initiator is a substance that can have a dissociation energy of 105 to 150 kJ/mol under the condition of 40 to 95 ° C and can generate free radicals to lead to the polymerization of olefin monomers. Potassium sulfate, ammonium persulfate, azobisisobutyronitrile, azobisisoheptanonitrile, and dibenzoyl peroxide. The polymerization method is emulsion polymerization with water as the dispersion medium. During polymerization, olefin The weight percent of each component of monomer, calcium carbonate particle, linking agent, emulsifier, initiator is: Olefin monomer: 54.5～97.8% Calcium carbonate particles: 1-25% Crosslinking agent: 0.1～15% Emulsifier: 1~5% Initiator: 0.1-0.5%.

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