JP2008001578A - Method for manufacturing metal oxide fine particle dispersion liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal oxide fine particle dispersion liquid substantially containing no impurity by using a solvent capable of easily forming a polymer composite, and to provide a polymer composite material in which the metal oxide fine particles are uniformly dispersed. <P>SOLUTION: The metal oxide fine particle dispersion liquid is manufactured by bringing a metal salt into contact with a basic ion exchange resin in a solvent other than alcohols and water. As the obtained dispersion liquid can easily dissolve various resins, polymer composite materials containing the metal oxide fine particles can be easily obtained. The polymer composite materials thus obtained are high in transparency and do not interfere the development of quantum effect of the metal oxide fine particles, because the aggregation among the metal oxide fine particles is suppressed in the composite materials. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a metal oxide fine particle dispersion.

  Metal oxide fine particles with a particle size of 20 nm or less are used in many applications such as catalysts, UV shielding materials, UV absorbing materials, fluorescent materials, luminescent materials, paints, and magnetic materials by utilizing their surface area and quantum characteristics. Is being considered. However, such metal oxide superparticles tend to aggregate because they have a large surface area and high surface activity, and it is difficult to produce fine particles in a stable dispersed state. Further, even if dispersed fine particles contain a large amount of impurities, the physical properties of the material are impaired. Therefore, a dispersed metal oxide fine particle dispersion containing no impurities is desired.

  As a method for producing metal oxide fine particles, there is a production method (top-down method) in which coarse particles having a size of 1 μm or more are mechanically pulverized, but the particle diameter of the obtained particles is usually 100 nm or more and exhibits a sufficient quantum effect. I can't get anything. On the other hand, a gas phase method is known as an example of the bottom-up method. The vapor phase method is a method in which the metal fine particles are collected while being oxidized by air by vaporizing the raw material metal at a high temperature and then cooling, and producing metal oxide fine particles having a particle diameter of 100 nm or less. Can do. However, it is difficult to prevent the particles from aggregating, and further, a large amount of energy is required to vaporize the metal, which is not suitable for mass production. There is also a drawback that it is difficult to keep the particle diameter uniform.

  A liquid phase method is known as a method for overcoming the above drawbacks. The method for producing metal oxide fine particles by a liquid phase method is a method in which a metal salt and hydroxide ions are reacted using a solvent. In the liquid phase method, fine particles having a particle diameter of 100 nm or less can be produced, and aggregation of the fine particles can be easily prevented (Non-Patent Document 1). Alkali metal hydroxides such as sodium hydroxide are generally used as raw materials for hydroxide ions, but quaternary ammonium hydroxide salts and ammonia can also be used (Patent Document 1, Non-Patent Document). 2). However, in the known liquid phase method, removal of by-products accompanying the synthesis of salts and the like is necessary, which is not economical. Examples of such a removal operation include a combination of centrifugation and washing, and filtration. Such an operation is time consuming and has a large loss, so it is difficult to increase productivity.

As a method for producing a metal oxide fine particle dispersion liquid substantially free of by-products, a method of bringing a metal salt alcohol solution into contact with a basic ion exchange resin as disclosed in Patent Document 2 is known.
JP-A-10-120419 JP 2003-286028 A R. Hoffmann et al. Phys. Chem 1987, 91, 3789 P. Mulvaney et al., Aust. J. et al. Chem. 2003, 56, 1051

  The problem to be solved by the present invention is to provide a method for producing a metal oxide fine particle dispersion containing substantially no impurities using a solvent capable of easily producing a polymer composite.

As means for solving the above problems, the present inventors have invented the following method.

That is, the present invention provides a method for producing a metal oxide fine particle dispersion, which comprises contacting a metal salt and a basic ion exchange resin in a solvent other than alcohol and water (Claim 1).

  2. The method for producing a metal oxide fine particle dispersion according to claim 1, wherein the basic ion exchange resin is a Bronsted type (OH type).

  The solvent is at least one solvent selected from the group consisting of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric triamide, tetrahydrofuran, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, ethyl acetate, and butyl acetate. A method for producing a metal oxide fine particle dispersion according to claim 1 or 2 (claim 3).

  4. The method for producing a metal oxide fine particle dispersion according to claim 1, wherein the metal element in the metal salt is zinc or titanium (claim 4).

  The method for producing a metal oxide fine particle dispersion according to any one of claims 1 to 4, wherein the metal salt is a carboxylic acid salt (claim 5).

  A method for producing a metal oxide fine particle dispersion according to any one of claims 1 to 5, wherein a basic ion exchange resin is filled in a tubular reactor and a solution of a metal salt is circulated. ).

  7. The method for producing a metal oxide fine particle dispersion according to claim 1, wherein the number average particle diameter of the metal oxide fine particles is 1 to 20 nm (claim 7).

  A method for producing a resin composition containing metal oxide fine particles obtained by dissolving a resin in the metal oxide fine particle dispersion produced by any one of claims 1 to 7 and then removing the solvent (claim 8). ).

The resin is at least one resin selected from the group consisting of acrylic resins, styrene resins, olefin resins, vinyl chloride resins, polyester resins, polycarbonate resins, and thermoplastic elastomers. Item 9. A process for producing a metal oxide fine particle-containing resin composition according to Item 8 (claim 9). It is.

    In the production method of the present invention, since a solution of a basic compound is not used as a raw material, a by-product as an impurity is not substantially generated. Therefore, there is no need for complicated purification operations, and industrial production is possible economically. Furthermore, when producing a polymer composite material containing metal oxide fine particles, the resin can be directly dissolved in the metal oxide fine particle dispersion, so that the operation is easier compared to conventional methods using alcohol as a solvent. Simple and excellent productivity. In addition, since such metal oxide fine particles having a number average particle diameter of 20 nm or less are very easily aggregated, it is difficult to obtain a transparent polymer composite. However, according to the method of the present invention, metal oxide fine particles are isolated. Therefore, aggregation can be prevented and a highly transparent polymer composite can be obtained.

  The method for producing a metal oxide fine particle dispersion of the present invention is characterized in that a metal salt and a basic ion exchange resin are brought into contact in a solvent other than alcohol and water. The solvent used in the present invention is not particularly limited as long as it is a solvent other than alcohol and water, but dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), hexamethyl are available in terms of availability and price. Phosphoric triamide (HMPA), tetrahydrofuran (THF), acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), toluene, ethyl acetate, and butyl acetate are preferred, and DMF, DMAc, DMSO, HMPA, acetone, and ethyl acetate are more preferable. These solvents are also preferable from the viewpoint of the solubility of the resin described later.

  The basic ion exchange resin used in the present invention is not particularly limited, but a Bronsted type (OH type) basic ion exchange resin is preferable in terms of a high yield of metal oxide fine particles. A Bronsted type (OH type) basic ion exchange resin is an ion exchange resin that can capture metal ions and release hydroxide ions, such as an ion exchange resin having ammonium ions. As such a Bronsted type (OH type) basic ion exchange resin, for example, Amberlyst A26 hydroxide form (manufactured by Sigma Aldrich Japan Co., Ltd.), Dowex Monosphere 550A, Dowex Marathon MSA (Dow Chemical Company) Manufactured).

  It is also possible to use a Cl-type ion exchange resin capable of releasing chlorine ions by converting it to an OH type by treatment with an alkali metal hydroxide or the like. Examples of such Cl-type basic ion exchange resins include Diaion SA10A, Diaion SA12A, Diaion SA20A, Diaion PA316, Diaion PA418, Diaion HPA25 (manufactured by Mitsubishi Chemical Corporation), and Dowex Marathon A. , Dowex Marathon A2 (Dow Chemical Co.), Duolite A113, Duolite A109D, Duolite A116 (Sumitomo Chemtex Co., Ltd.), Amberlite IRA400J CL, Amberlite IRA400T CL, Amberlite 4400 CL, Amberlite IRA402J CL, Amberlite IRA402BL CL, Amberlite IRA458RF CL, Amberlite IRA900J CL, Amberlite IRA410J (manufactured by Organo (Ltd.)) CL, Amberjet 4200 chloride form (manufactured by Sigma-Aldrich Japan Co., Ltd.), and the like.

  These may be used alone or in combination. The base of these ion exchange resins is not particularly limited, and a polystyrene type, a polyacrylic acid type and the like are typical, but a polystyrene type is preferable in terms of excellent durability when repeatedly used. The form of the ion exchange resin is not particularly limited, and either a gel type or a porous type can be used, but a porous type is preferable in terms of high reactivity. In general, since many basic ion exchange resins contain a large amount of moisture, it is preferable to perform a dehydration treatment before use.

  The amount of the basic ion exchange resin used in the present invention is not particularly limited, but in terms of increasing the yield of the metal oxide fine particles, the amount of the base is preferably 1 mol or more, preferably 2 mol or more, based on 1 mol of the metal salt. More preferred.

  It does not specifically limit as a metal element of the metal salt used by this invention, What is necessary is just to select according to the metal oxide to manufacture. In terms of the usefulness of the metal oxide fine particles obtained, Group II, Group III, Group IV, and Group V metals are preferable, and zinc, titanium, gallium, zirconium, cadmium, and indium are more preferable, and zinc and titanium Is most preferred. The form of the metal salt is not particularly limited, but chloride, bromide, iodide, nitrate, sulfate, carbonate, carboxylate, and sulfonate are preferable from the viewpoint of availability and solubility. More preferred are acetate, propionate, laurate, oleate, adipate, hydroxyacetate and the like. The metal salt can be used as an anhydride or a hydrate. In the present invention, the metal salts may be used alone or in combination.

  In the present invention, the method for bringing the metal salt in the solvent into contact with the basic ion exchange resin is not particularly limited, and a batch method in which the solvent, the metal salt, and the basic ion exchange resin are placed in a reaction vessel in an arbitrary order and stirred. And a continuous method in which a basic ion exchange resin is filled in a tubular reactor and a metal salt solution is circulated. Among these, the continuous method is preferable because of high reaction efficiency and high productivity. In the present invention, the basic ion exchange resin can be regenerated into an OH type by contacting with a solution such as an alkali metal hydroxide after the reaction. In the case of the continuous method, since it can be regenerated simply by switching between the metal salt solution and the alkali metal hydroxide solution, it is simple and highly productive. After regeneration, it is preferable to remove excess alkali metal hydroxide and the like using a dehydrated solvent.

  Although the number average particle diameter of the metal oxide fine particles obtained by the production method of the present invention is usually 100 nm or less, 1 to 20 nm is preferable and 1 to 10 nm is more preferable in that a quantum size effect appears remarkably. Typical parameters for controlling the number average particle size are the temperature at which the metal salt and the ion exchange resin are contacted, the concentration of the metal salt at the time of contacting the metal salt and the ion exchange resin, and the reaction time for contact. It is. Generally, when the temperature is increased, the concentration is increased, and the reaction time is increased, the number average particle diameter tends to increase. Therefore, in order to reduce the number average particle diameter of the metal oxide fine particles, it is effective to keep the reaction temperature as low as possible, reduce the concentration, and shorten the reaction time.

  However, these conditions differ depending on the type of raw material metal salt or basic ion exchange resin, the type of metal oxide to be produced, and there is a tradeoff between productivity and yield. Just choose. As an example of these conditions, the temperature when the metal salt and the ion exchange resin are brought into contact is 10 to 80 ° C., and the concentration of the metal salt when the metal salt and the ion exchange resin are brought into contact is 0. 0.005 to 0.5 mol / L can be exemplified as a preferred example of a reaction time of 5 to 100 minutes, and one or more of these conditions can be appropriately combined.

  Since the metal oxide fine particle dispersion obtained in the present invention uses a solvent other than alcohol and water, the general-purpose resin can be easily dissolved as compared with the case where these solvents are used, and therefore contains metal oxide fine particles. A resin can be obtained easily. That is, a polymer composite material can be obtained by dissolving a desired resin in the metal oxide fine particle dispersion and removing the solvent. The method for removing the solvent is not particularly limited, and examples thereof include removal by distillation, precipitation of the resin by addition of a poor solvent to the resin, and removal of the solvent by a casting method or spin coating to obtain a film. Moreover, you may use for coating liquids, paints, etc. as it is, without removing a solvent.

  In the metal oxide fine particle-containing resin of the present invention, the resin that can be used is not particularly limited, and may be a synthetic resin or a polymerized material using a natural product as a raw material, and is dissolved in a solvent depending on the purpose. You can use what you want.

  In terms of the usefulness and versatility of the resulting composite material, polymethyl methacrylate (PMMA or acrylic resin), a copolymer of methyl methacrylate and other (meth) acrylic acid ester or (meth) acrylic acid, methacrylic acid, Acrylic resins such as copolymers of methyl acid and styrene (MS resin), copolymers of methyl methacrylate and acrylonitrile; polystyrene (PS), copolymers of styrene and α-methylstyrene, styrene and p-styrene sulfone Copolymers with acids, copolymers of styrene and acrylonitrile (SAN), styrene resins such as high impact polystyrene (HIPS); polyethylene (PE), polypropylene (PP), maleic acid modified polypropylene, polyolefin wax, etc. Olefin resin; polyvinyl chloride (P C), polyvinylidene chloride (PVDC), chlorinated polyvinyl chloride (CPVC), chlorinated polyethylene, vinyl chloride and vinyl acetate copolymers, etc .; polyethylene terephthalate (PET), polybutylene terephthalate (PBT) ), Polycaprolactone (PCL), polylactic acid (PLA), polyhydroxybutanoic acid (PHB), a copolymer of hydroxybutanoic acid and hydroxyhexanoic acid (PHBH); a polycarbonate resin; a styrene thermoplastic Elastomer (SBC), vinyl chloride thermoplastic elastomer (TPVC), olefin thermoplastic elastomer (TPO), urethane thermoplastic elastomer, polyester thermoplastic elastomer, nitrile thermoplastic elastomer, polyamide heat Thermoplastic elastomers such as plastic elastomer (TPAE) are preferred. These may be used alone or in combination.

  In general, metal oxide fine particles having a number average particle diameter of less than 20 nm are very easily aggregated, and it is difficult to uniformly disperse them in the resin. Therefore, it is difficult to obtain a transparent polymer composite material. Since the metal oxide fine particle-containing resin of the present invention is dispersed in the resin in a state where the metal oxide fine particles are not aggregated, the transparency is high and the quantum effect derived from the nanosize is not lost. Therefore, the metal oxide fine particle-containing resin of the present invention is excellent in heat resistance, weather resistance, UV resistance, scratch resistance, and mechanical strength, and further, a light emission phenomenon due to ultraviolet irradiation is recognized due to the quantum effect of the metal oxide fine particles. Because of these characteristics, it can be used for various surface protective films and coatings, display materials, luminescent materials, insect-proof films, UV-absorbing materials, interlayer films for laminated glass, paints and the like.

Hereinafter, examples will be shown to further clarify the features of the present invention.
Measurement of number average particle diameter of metal oxide fine particles in resin composition: After making an ultrathin section from the obtained resin composition using an ultramicrotome (Ultracut UCT manufactured by Leica), a transmission electron microscope (TEM) ) (JEOL JEM-1200EX) was used to photograph the dispersed state of the metal oxide fine particles at a plurality of locations at a magnification of 10,000 to 400,000 times. The number average particle size of the particles was calculated by measuring the particle size of at least 100 particles in the obtained TEM photograph.

(Example 1)
An ion exchange resin Amberlyst A26 hydroxyl form (manufactured by Sigma-Aldrich Japan, 6.3 mL, 6.0 mmol) was placed in a reactor equipped with a reflux condenser, a nitrogen gas inlet tube, a thermometer, and a magnetic stirrer. DMF (manufactured by Wako Pure Chemical Industries, Ltd., 100 mL) dried with molecular sieves 3A (manufactured by Wako Pure Chemical Industries, 5 g) as a solvent was added overnight, and potassium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., 5.6 g) was added. , 0.1 mol) was added, and the mixture was stirred for 1 hour, and then the DMF solution in the system was removed using a cannula and a syringe to regenerate the ion exchange resin. Drying DMF (100 mL) was newly added, and the washing operation of removing the DMF solution after stirring for 30 minutes was performed 3 times. Thereafter, dry DMF (100 mL) was newly added and allowed to stand for 30 minutes to obtain a DMF dispersion of ion exchange resin. The supernatant DMF solution (about 0.1 mL) was taken with a syringe, and the water content was analyzed with a Karl Fischer moisture meter (MKC-610, manufactured by Kyoto Electronics Industry Co., Ltd.).

After heating the obtained DMF dispersion of the ion exchange resin to 40 ° C. with a water bath, Zn (OAc) ₂ .2H ₂ O (manufactured by Nacalai Tesque Co., Ltd., 0.44 g, 2 mmol) was added and stirred for 45 minutes. went. After allowing to cool, the dispersion liquid was decanted and the supernatant liquid containing ZnO fine particles was transferred to another glass container and separated from the ion exchange resin. This dispersion was colorless and transparent, and no change such as aggregation was observed in the ZnO fine particles after storage for 2 months (sealed and 0 ° C.).

  This DMF dispersion of ZnO fine particles showed an emission spectrum of 510 nm with respect to 314 nm excitation light by a spectrofluorimeter (manufactured by JASCO Corporation, FP-6500 type). After adding polymethyl methacrylate (Sumipex MH, manufactured by Sumitomo Chemical Co., Ltd., 0.8 g) to the DMF dispersion (4.9 mL) of the ZnO fine particles and stirring for 30 minutes to dissolve, a glass petri dish (diameter 8.8 cm). ) And dried for 120 minutes with a vacuum dryer (degree of vacuum: about 1.0 Torr) to obtain a transparent film. This film had a thickness of 87 μm, and it was 0.83% when haze measurement was performed using COH300A (manufactured by Nippon Denshoku Industries Co., Ltd.). Observation of the film with a transmission electron microscope revealed that the ZnO fine particles were uniformly dispersed in the resin, and the number average particle diameter of the fine particles was 7 nm. The content of ZnO fine particles was estimated by burning this film and measuring the ash content, and it was 1.0 wt%.

(Comparative Example 1)
In the same manner as in Example 1, except that the cation exchange resin Amberlyst 15 hydrogen form (manufactured by Sigma Aldrich Japan Co., Ltd., 3.3 mL, 6.0 mmol) was used instead of the ion exchange resin Amberlyst A26 hydrogen form. An attempt was made to synthesize a fine DMF dispersion. However, since the obtained DMF dispersion did not show an emission spectrum with respect to excitation light of 314 nm with a spectrofluorimeter, it was confirmed that no ZnO fine particles were generated.

(Comparative Example 2)
In place of the DMF dispersion (4.9 mL) of ZnO fine particles of Example 1, A 0.02 M methanol dispersion (4.9 mL) of ZnO microparticles prepared according to the method of Spanhel et al. (L. Spanhel et al .; J. Am. Chem. Soc., 113, 2826 (1991)) and DMF (20 mL) A polymethyl methacrylate film containing ZnO fine particles was prepared in the same manner as in Example 1 except that it was mixed to obtain a DMF dispersion, and this was used. However, the film did not become transparent but became a cloudy film (haze 13.5%).

(Example 2)
A glass tube having an inner diameter of 1 cm and a length of 10 cm was filled with an ion exchange resin Amberlyst A26 hydroxyl form (Sigma Aldrich Japan Co., Ltd., 6.3 mL, 6.0 mmol), and a liquid feeding tube and a liquid discharging tube were attached. A thermocouple for temperature measurement and a ribbon heater were attached to the glass tube, and a dry DMF solution (120 mL) of potassium hydroxide (10 g) was introduced into the glass tube at room temperature using a liquid feed pump. Subsequently, dry DMF (800 mL) was introduced using a liquid feed pump to replace the potassium hydroxide solution in the glass tube. The temperature of the glass tube is kept at 50 ° C. with a ribbon heater, and a solution in which Zn (OAc) ₂ .2H ₂ O (manufactured by Nacalai Tesque Co., Ltd., 0.44 g, 2 mmol)) is dissolved in dry DMF (100 mL) is fed. It introduced into the glass tube using the pump. By adjusting the liquid feeding speed to 0.25 mL / min, the contact time between zinc acetate and the ion exchange resin was adjusted to 25 minutes. The reaction solution coming out of the glass tube was taken in a receiver cooled with ice water. The obtained DMF dispersion of ZnO fine particles was colorless and transparent, and no change such as aggregation of ZnO fine particles was observed even after storage for 3 months (sealed at 0 ° C.). This DMF dispersion showed a 511 nm emission spectrum with respect to 314 nm excitation light by a spectrofluorimeter (manufactured by JASCO Corporation, FP-6500 type).

  A polymethyl methacrylate (Sumipex MH, manufactured by Sumitomo Chemical Co., Ltd., 1.0 g) is added to the DMF dispersion (5.5 mL) of the ZnO fine particles to obtain a solution, and a bar coater (K303 multi-coater, RK Print Coat Instruments, LTD). A film having a thickness of 110 μm was prepared by a casting method. The obtained film had high transparency, and it was 0.75% when haze measurement was performed using COH300A (manufactured by Nippon Denshoku Industries Co., Ltd.). Observation of the film with a transmission electron microscope revealed that the ZnO fine particles were uniformly dispersed without aggregating in the resin, and the number average particle size of the fine particles was 5.3 nm. The content of ZnO fine particles was estimated by burning this film and measuring the ash content, and it was 0.9 wt%.

As described above, according to the method of the present invention, the metal oxide fine particles can be dispersed in the resin without isolation, and a highly transparent polymer composite can be obtained.

Claims (9)

  A method for producing a metal oxide fine particle dispersion, comprising contacting a metal salt and a basic ion exchange resin in a solvent other than alcohol and water.   2. The method for producing a metal oxide fine particle dispersion according to claim 1, wherein the basic ion exchange resin is a Bronsted type (OH type).   The solvent is at least one solvent selected from the group consisting of dimethylformamide, dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoric triamide, tetrahydrofuran, acetone, methyl ethyl ketone, methyl isobutyl ketone, toluene, ethyl acetate, and butyl acetate. The method for producing a metal oxide fine particle dispersion according to claim 1 or 2, wherein   4. The method for producing a metal oxide fine particle dispersion according to claim 1, wherein the metal element in the metal salt is zinc or titanium.   The method for producing a metal oxide fine particle dispersion according to any one of claims 1 to 4, wherein the metal salt is a salt of a carboxylic acid.   The method for producing a metal oxide fine particle dispersion according to any one of claims 1 to 5, wherein a basic ion exchange resin is filled in a tubular reactor and a metal salt solution is circulated.   The number average particle diameter of metal oxide fine particles is 1-20 nm, The manufacturing method of the metal oxide fine particle dispersion liquid in any one of Claim 1 to 6 characterized by the above-mentioned.   A method for producing a metal oxide fine particle-containing resin composition obtained by dissolving a resin in a metal oxide fine particle dispersion produced by the method according to claim 1 and then removing the solvent. The resin is at least one resin selected from the group consisting of acrylic resins, styrene resins, olefin resins, vinyl chloride resins, polyester resins, polycarbonate resins, and thermoplastic elastomers. Item 9. A method for producing a resin composition containing metal oxide fine particles according to Item 8.