JP2006299126A - Method for modifying surface of nano-filler, polymer nano-composite and method for producing polymer nano-composite - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer nano-composite containing a surface modified nano-filler excluding bad influences of dysfunction such as filler aggregation, deterioration of molecular weight and discoloring by a surface modifier such as a coupling agent which cannot chemically be combined with the nano-filler, a condensate, etc., formed by mutually combining the surface modifier. <P>SOLUTION: The polymer nano-composite is produced as follows. The nano-filler is dispersed in a solvent and a prescribed modifier is added to modify the surface. The solvent containing the nano-filler is directly washed and the free modifier present as a residual component of the modifier in the solvent is removed to afford a surface modified nano-filler. The resultant surface modified nano-filler is compounded and dispersed in a prescribed organic polymer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for modifying the surface of a nanofiller to obtain a polymer nanocomposite that is excellent in properties such as transparency, mechanical properties, and moldability and that is extremely useful for producing an industrially advantageous polymer nanocomposite. And a method for producing a polymer nanocomposite, and the polymer nanocomposite.

  As a technique to improve various physical properties of organic polymers, while maintaining the flexibility, low density and moldability that are the characteristics of organic polymers, the high strength, high elastic modulus, heat resistance, and electrical characteristics that are the characteristics of inorganic compounds As a method for improving the physical properties, composite materials using nano-order level inorganic fine particles instead of conventional glass fiber or crushed resin, so-called polymer nano-materials, have been developed. Composites are gaining attention. Examples of such composite materials include “composite materials and manufacturing methods thereof (Patent No. 2519045 / Toyota Chuken)” and “polyamide composite materials and manufacturing methods thereof (Japanese Patent Publication No. 7-47644 / Ube Industries, etc.)”, “Polyolefin-based composite material and production method thereof (No. 10-30039 / Showa Denko)” and the like.

  Conventionally, inorganic fine particles such as silicon dioxide, titanium dioxide, and aluminum oxide have been widely used as organic polymer fillers. In applying inorganic fine particles to this application, surface modification of inorganic fine particles has been carried out for the purpose of improving dispersibility, developing characteristics that have not been heretofore, and improving affinity with other substances.

  In polymer nanocomposites, dispersion of inorganic fine particles at the nano-order level is a major point for improving physical properties. By appropriately modifying the surface of inorganic fine particles, the dispersion on the nano-order is maintained while preventing aggregation. It can be used as a “nanofiller”. As a result, the interaction with the organic polymer can be obtained, and further, it can contribute to the adhesiveness with other substances.

  As a means for surface modification of the nanofiller, a method of reacting an organic metal such as alkyllithium or alkylaluminum, a titanium coupling agent, a silane coupling agent or a silylating agent with a hydroxyl group on the surface of the nanofiller is generally used. It is.

  On the other hand, in order to impart a sufficient function to the nanofiller, it is necessary to bind more functional chemical species. For this purpose, more surface modifiers will be used, but especially with silane coupling agents and silylating agents, coupling agents that have not been chemically bonded to the nanofiller, As a result, the condensate formed by bonding has a problem that the effect of adding nanofillers and the function as a polymer nanocomposite are impaired.

  Furthermore, for transparent resins such as acrylic resin, vinyl resin, polyester resin, and polycarbonate resin, when inorganic fine particles are aggregated, the transparency is rapidly lost. If the behavior that connects the particles after oligomerization of the coupling agent is allowed, it becomes a source of aggregation, so it is necessary to remove unreacted substances and condensates as much as possible.

  In order to reduce free components (hereinafter referred to as “free modifiers”) composed of a condensate formed by coupling unreacted coupling agents and coupling agents as described above, Consideration has been made.

  JP-A-6-210857 (“Inkjet recording head manufacturing method” / Seiko Epson) and JP-A-6-93121 (“Water-repellent member and manufacturing method thereof” / Matsushita Electric Industrial Co., Ltd.) In this method, unreacted substances are removed and the method is limited to a thin layer structure.

  Studies on fillers for bulk compositions are also being conducted. In JP-A-2001-233963 (“Production method of resin composition” / Bridgestone), after adding a silane coupling agent to a filler, a two-stage treatment is performed to reduce unreacted components. In addition, no positive removal means are taken and the presence or absence of unreacted substances is defined by the residual amount of alkoxy groups, and free oligomer components and condensates are not taken into consideration. In JP-A-2000-95517 (“Method for producing inorganic fine particles” / Toray), the reaction of unreacted substances is promoted under high-temperature and high-humidity conditions. Since the method is limited to the method treatment, the crosslinking between the fillers due to unreacted substances proceeds during the promotion of the reaction, and agglomeration cannot be avoided.

  There is also an example in which a sol is filtered for purification. In JP-A-1-103904 (“Method for producing inorganic spherical particles” / Nippon Shokubai Kagaku Kogyo Co., Ltd.), ultrafiltration treatment of sol is performed. This is the basic substance (ammonia, amines) used for the catalyst. In the first place, the surface is not modified at all, and finally purified for the purpose of obtaining a dry submicron particle powder. On the other hand, in JP-A-10-316406 ("Inorganic fine particles and production method thereof" / Toray), solid-liquid separation is performed after heating in a solvent after modification of the filler. This is a technology for larger fillers, and is filtered using a membrane filter with a pore size of 1 μm. Furthermore, the filler is separated from the dispersion medium by solid-liquid separation and becomes almost solid, which makes it easy to agglomerate. For this reason, it cannot be applied at all to nanofillers having a particle size of several tens of nanometers. Therefore, nanocomposites with good particle dispersion cannot be obtained by these methods.

  As described above, in polymer nanocomposites using nanofillers, several methods have been studied for removing free modifiers during filler surface modification, but a decisive method has not yet been established. However, it was necessary to further consider the application to bulk composites, the maintenance of dispersion in the nano-order, and the maintenance of transparency in blending with acrylic resins, vinyl resins, polyester resins, and polycarbonate resins.

Japanese Patent No. 2519045 Japanese Examined Patent Publication No. 7-47644 Japanese Patent Laid-Open No. 10-30039 JP-A-6-210857 JP-A-6-93121 JP 2001-233963 A JP 2000-95517 JP-A-1-103904 JP-A-10-316406

  The object of the present invention is to adversely affect the coupling agent that could not be chemically bonded to the nanofiller described above, or a condensate formed by bonding these coupling agents, that is, filler aggregation, molecular weight reduction, coloring, etc. It is to obtain a polymer nanocomposite using a surface-modified nanofiller with little functional deterioration.

In order to achieve the above object, the present invention provides:
A step of dispersing the nanofiller in a solvent and adding a predetermined modifier to surface-modify,
Washing the solvent containing the nanofiller directly, removing the free modifier present as a residual component of the modifier in the solvent, and purifying;
A method for modifying the surface of a nanofiller, characterized by comprising:
The present invention relates to a polymer nanocomposite comprising a surface-modified nanofiller obtained by the above method and an organic polymer.

  As a result of intensive studies to achieve the above object, the present inventors performed surface treatment on the nanofiller without drying or solid-liquid separation after arbitrarily modifying the surface of the nanofiller. It has been found that, for example, by directly washing a sol or slurry solution, the free modifier, which is a residual component of the surface modifier, present in the solution can be effectively almost completely removed. . Therefore, the surface-modified nanofiller only contains the original modifier chemically attached (bonded) to the surface of the nanofiller, and simply includes the free modifier attached to the surface or the like. Therefore, even when a desired polymer nanocomposite is obtained by blending in a predetermined organic polymer, the polymer nanocomposite does not contain a free modifier. As a result, in the polymer nanocomposite, due to the free modifier and the condensate of the free modifier, characteristics such as reduction in mechanical strength due to filler aggregation and molecular weight reduction of the polymer nanocomposite, and coloring. The above deterioration can be suppressed.

  As described above, according to the present invention, due to a surface modifier such as a coupling agent that could not be chemically bonded to the nanofiller, or a condensate formed by bonding the surface modifiers together. In addition, a polymer nanocomposite containing a surface-modified nanofiller that eliminates the adverse effects of functional degradation such as filler aggregation, molecular weight reduction, and coloring can be obtained. Therefore, the polymer nanocomposite can improve mechanical strength and dimensional stability without sacrificing its transparency, and has the characteristics of being able to suppress deformation, warping, distortion, etc. at high temperatures. Therefore, it is suitable for members that require these functions, for example, electronic components, optical components, automobile interior and exterior materials that are subject to heat cycle load, and transparent members, fixtures, and furniture used in home appliances and houses. It can be used suitably.

  Hereinafter, other features and advantages of the present invention will be described based on the best mode for carrying out the invention.

(Nanofiller surface modification method)
<Preparation of nano filler>
In order to obtain a polymer nanocomposite that is the object of the present invention, a surface-modified nanofiller is first prepared. In this manufacturing process, first, a predetermined nanofiller is prepared. The nanofiller is not particularly limited, and any nanofiller can be selected and used so as to obtain predetermined characteristics by being added to the organic polymer. Specific examples include (nano) particles selected from the group consisting of silica, alumina, aluminum hydroxide, calcium carbonate, titania, iron oxide, cerium oxide, zinc oxide, hydroxyapatite, carbon, gold, silver and mixtures thereof. can do. In view of availability, cost, ease of exerting the effect of the dispersant, and the like, (nano) particles made of silica and alumina are preferable.

  In addition, the nanofiller is desirably a commercially available sol type in view of handling, and an organosol dispersed in an organic solvent is particularly desirable in consideration of compatibility with an organic polymer. As an organic solvent for preparing the organosol, any solvent can be used. For example, an aliphatic hydrocarbon solvent such as pentane, hexane, heptane, decane, and cyclohexane, and an aromatic solvent such as benzene, toluene, and xylene. Hydrocarbon solvents, ketone solvents such as acetone, methyl ethyl ketone, methyl isoptyl ketone and cyclohexanone, ester solvents such as methyl acetate, ethyl acetate, propyl acetate and butyl acetate, ethers such as diethyl ether, dimethoxyethane, tetrahydrofuran and dioxane Solvents, methanol, ethanol, propanol, isopropanol, butanol, cyclohexanol and other alcohol solvents, chloroform, 1,2-dichloroethane, methylene chloride, carbon tetrachloride, trichloroethylene, Halogen solvents such as lachloroethylene, chlorobenzene, tetrachloroethane, promobenzene, 1,3-bis (trifluoromethyl) benzene, trifluoromethylbenzene, 1,1,2-trichloro-1,2,2-trifluoro Fluorine-based organic solvents such as ethane, aprotic polar solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone can be used.

  In addition, even if it is a powdery nanofiller, once it is dispersed in an organic solvent and then modified, it can be made into a sol and used as an organosol in the synthesis of the desired nanofiller composite. be able to.

  The shape of the nanofiller is not particularly limited, and not only a general substantially spherical shape, but also a rectangular parallelepiped shape, a plate shape, a linear shape such as a fiber, a branched shape, etc. can be used.

  The nanofiller preferably has a major axis of 2 to 200 nm in order to develop the desired performance as a polymer nanocomposite. By making the major axis of the inorganic fine particles considerably smaller than the lower limit of visible light wavelength of 380 nm, the visible light is hardly scattered by the inorganic fine particles, and a nanocomposite having excellent physical properties can be obtained without sacrificing transparency. . More preferably, the major axis is 100 nm or less. The major axis here means the diameter if the shape of the inorganic fine particles is substantially spherical, and the longest side if the shape is a rectangular parallelepiped or plate. Particles smaller than 2 nm are difficult to disperse and expensive. If it exceeds 200 nm, there is a risk that transparency may be hindered.

  The method for producing the nanofiller is not particularly limited, and may be obtained by any method such as a gas phase method, a sol-gel method, a colloidal precipitation method, a molten metal spray oxidation method, or arc discharge.

<Surface modification treatment>
After preparing a predetermined nanofiller as described above, surface modification treatment is performed on the nanofiller using a surface modifier. This surface modification treatment is performed by dispersing the nanofiller in a predetermined solvent, specifically an organic solvent, and adding the surface modifier to cause a condensation reaction. At this time, the solution subjected to the surface modification can be appropriately heated to a temperature not higher than the boiling point of the solvent, and a method such as ultrasonic wave, microbead mill, stirring, and high-pressure emulsification is used in the dispersion mixing. You can also. Moreover, in the said stirring, arbitrary things, such as a magnetic stirrer and a motor with a stirring blade, can be used according to a manufacturing scale. The surface modifier can be diluted in advance with an organic solvent.

  Although the said surface treating agent is not specifically limited, For example, organometallic compounds, such as a silane coupling agent, a silylating agent, a titanium coupling agent, alkyllithium, and alkylaluminum, can be mentioned. Of these, silane coupling agents and silylating agents are particularly preferred from the viewpoints of ease of use and cost.

  A silane coupling agent has a structure in which an organic substituent having affinity or reactivity for organic substances is chemically bonded to a hydrolyzable silyl group having affinity or reactivity for inorganic materials. Silane compound. Examples of the hydrolyzable group bonded to silicon include an alkoxy group, a halogen, an acetoxy group, and an alkenoxy group. Usually, an alkoxy group, particularly a methoxy group and an ethoxy group are used.

  Examples of the organic substituent include an alkyl group, an aryl group, an amino group, a methacryl group, an acrylic group, a vinyl group, an epoxy group, and a mercapto group. Specifically, alkyltrichlorosilane, alkyltrialkoxysilane, alkyldialkoxychlorosilane, dialkylalkoxychlorosilane, trialkylchlorosilane, trialkylalkoxysilane, aryltrichlorosilane, aryltrialkoxysilane, diaryldichlorosilane, diaryldialkoxysilane, Triarylchlorosilane, triarylalkoxysilane, γ-aminopropyltrialkoxysilane, γ-aminopropylmethyldialkoxysilane, γ-ureidopropyltrialkoxysilane, γ-methacryloxypropyltrialkoxysilane, vinyltrialkoxysilane, vinyltri Acetoxysilane, vinyltrichlorosilane, γ-glycidoxypropyltrialkoxysilane, γ-glycy Carboxypropyl methyl dialkoxysilane, and the like can be exemplified (3,4-epoxycyclohexyl) ethyl trialkoxysilane, .gamma.-mercaptopropyl trialkoxysilane, .gamma.-chloro-Bro built trialkoxysilane.

  Examples of the silylating agent include trimethylsilylating agents, alkylsilanes, and allylsilanes. Examples of the trimethylsilylating agent include trimethylchlorosilane, hexamethyldisilazane, n-trimethylsilylimidazole, bis (trimethylsilyl) urea, trimethylsilylacetamide, bistrimethylsilylacetamide, trimethylsilyl isocyanate, trimethylmethoxysilane, and trimethylethoxysilane. it can. Examples of the alkylsilanes include 1,6-bis (trimethoxysilyl) hexane, dimethylsilyl diisocyanate, and methylsilyl triisocyanate. Examples of allylsilanes include phenylsilyl triisocyanate.

  Further, as the solvent, it is desirable to use a solvent that can disperse the nanofiller and dissolve the surface modifier. When a solvent with low dispersibility is used, aggregation of nanofillers occurs, and when a solvent with low solubility is used, the modifier is separated. Specifically, it can be used by appropriately selecting from the solvents used in preparing the organosol described above.

<Removal and purification of free modifier>
Next, after the surface modification treatment is completed, the solvent in which the nanofiller remains is directly washed, and chemically bonded to the surface of the nanofiller and free modification that does not contribute to the surface modification. The material is removed and purified. In the present invention, the free modifier is removed by directly washing the solvent without applying a technique such as drying or solid-liquid separation to the solvent in which the free modifier remains. Yes. Therefore, removal and purification of the free modifier can be performed efficiently.

  In addition, it is preferable that the content of the surface modified nanofiller in the solvent before and after the direct washing of the solvent is substantially the same. Thereby, the loss of the surface-modified nanofiller due to the direct cleaning can be prevented. Note that “substantially the same” means that the concentration after cleaning is in the range of 0.8 to 1.2 when the concentration before cleaning is 1.

  The direct washing is preferably performed using at least one of ultrafiltration and centrifugation. This makes it possible to easily perform direct cleaning that satisfies the above-described requirements.

Ultrafiltration is a filtration technique applied at the 2 nm to 100 nm level in membrane separation, and is a technique that is originally used for protein removal and purification in an aqueous solvent. In the present invention, this is used in an organic solvent system and adopted as a means for removing a free modifier. The filter membrane may be selected appropriately by selecting a molecular weight cut off so that the free trade agent can pass through and the nanofiller hardly passes through. Any commercially available ultrafiltration device may be used according to the scale. For example, Kuraray's "CHARACTER ^(R) " series, Organo's "Olfine MTA" series, Daisen Menprene Systems'"MOLSEP" Series.

  As the ultrafiltration operation, a circulation flow path is set together with a pump in the ultrafiltration device, the modified nanofiller-dispersed organosol is circulated while being pressurized, and the solvent is flowed to the filtrate side to wash away the free modifier. At this time, it is extremely important to replenish the organosol side with a pure solvent as needed to keep the sol concentration substantially constant, and it is possible to prevent filler aggregation and precipitation due to the increase in concentration.

  When centrifuging, in a small amount, use a general ultracentrifuge to repeat the centrifugation several tens of times while replenishing the volatile components of the solvent. The supernatant solvent is discarded when the height becomes about 30%, and the filler is recovered in the form of a slurry. In the case where the scale is large, for example, a decanter for nano particles “Separating plate type Centrifugy DZ” manufactured by Mitsubishi Chemical Corporation can be used. In any case, aggregation of the nanofiller can be prevented by replenishing the solvent so that the concentration becomes the same as that at the start immediately after the nanofiller slurry is collected.

<Remaining amount management / analysis>
In order to confirm whether or not the free modifier can be removed reliably, the bond of “Si-substituent” contained in the silane coupling agent / silylating agent, which is a modifier, can be detected. ²⁹ Si -NMR analysis is the most effective technique. When one organic substituent is bonded to the Si atom, that is, Si represented by the formula RSiO _3/2 is commonly called “T unit”, and its peak is related to the electron withdrawing / donating properties of the substituent. However, in general, the chemical shift when TMS is Oppm appears in the range of -40 to -85 ppm. When two organic substituents are bonded to the Si atom, that is, Si represented by the formula of RR'SiO _2/2 is commonly called “D unit”, and its peak is generally at a chemical shift of 5 to −45 ppm. Appears in range. When three organic substituents are bonded to the Si atom, that is, Si represented by the formula RR′R ″ SiO _2/2 is commonly called a D unit, and its peak generally has a chemical shift of 30 to −20 ppm. Appears in the range of.

By performing ²⁹ Si-NMR analysis of the surface modifier used, the peak position when not reacted can be confirmed. In general, the chemical shift shifts to one side by hydrolysis, but since it shifts with a width of 5 to 10 ppm with respect to the raw material peak, it can be easily identified. ^{In 29} Si-NMR analysis, the relaxation time is shortened by adding a trace amount of a complex such as Fe or Cr as a relaxation reagent. Due to the effect of the relaxation reagent, the peak of the modifying agent and its degradation product becomes sensitive and easy to detect. On the other hand, the Si atom derived from the modifier bonded to the nanofiller surface has a very high degree of restraint, and does not form a sharp peak even in the presence of a relaxation reagent. Therefore, ²⁹ Si-NMR analysis of the solution was performed before and after the removal of the free modifier, and the chart of the same range was obtained to measure the height of the sharp peak, so that the remaining free modifier was measured. You can manage the amount. That is, when the peak is high, the residual amount of the free modifier is large, and when the peak is low, the residual amount of the free modifier is small.

Although it is desirable that the reduction amount of the free modifier is reduced to a level of 1/10 before the removal operation, in practice, the operation of the present invention can be substantially reduced to below the detection limit. The modifier bonded to the surface of the nanofiller can be detected by Soxhlet extraction of the nanofiller and then solid ²⁹ Si-NMR analysis such as CP / MAS-NMR.

<Polymer nanocomposites>
The polymer nanocomposite of the present invention comprises a surface-modified nanofiller obtained through the above-described surface modification treatment and free modifier removal purification process, and a predetermined organic polymer. In the surface-modified nanofiller, the free modifier is almost completely removed efficiently through the steps as described above. Therefore, when the polymer nanocomposite is prepared by dispersing and blending in the organic polymer, The free modifier may be substantially absent from the composite. In addition, this “substantially nonexistent” means, for example, the case where the above-described ²⁹ Si-NMR analysis is performed on the polymer nanocomposite and the peak thereof is below the detection limit.

Any organic polymer can be used as the organic polymer, but light transmittance is sufficient to ensure sufficient transparency of the target polymer nanocomposite by taking advantage of the characteristic of nanofiller that does not scatter visible light. It is preferably composed of 80% or more transparent resin. Such transparent resins include polycarbonate resin (PC), acrylic resins such as PMMA and PMA, polyethylene terephthalate (PET), transparent polypropylene resin, transparent ABS resin, transparent polystyrene, transparent eboxy resin, polyarylate (PAR), and polysulfone. (PSF),
Polyether sulfone, transparent nylon resin, transparent polybutylene terephthalate (PBT), transparent fluororesin, poly-4-methylpentene (PMP), transparent phenoxy resin, transparent polyimide resin, transparent phenol resin, MS resin (methyl metallate styrene) Monomer copolymer) and the like. Among these, from the viewpoint of easy availability and cost, it is desirable to use any of acrylic resin, polyester resin, and polycarbonate resin.

  The concentration of the nanofiller in the nanocomposite in the present invention is preferably in the range of 0.2 to 60% by weight as the solid content. If it is less than 0.2% by weight, it is difficult to recognize improvement of various properties such as mechanical strength. If it exceeds 60% by weight, not only the increase in specific gravity can not be ignored, but also the decrease in impact strength cannot be ignored. Generally, when a large amount of inorganic fine particles are blended with a polymer, the impact strength is reduced. However, since the nanocomposite of the present invention is a uniform dispersion of nano-order inorganic fine particles, the decrease in impact strength is practically small, but 60% by weight. If it exceeds, this cannot be ignored. More preferably, it is 1 to 30% by weight.

(Production method of polymer nanocomposite)
The method for producing the polymer composite of the present invention can be appropriately selected according to the type of the organic polymer constituting the polymer nanocomposite, but in order to avoid aggregation of the nanofiller, mixing with the organic polymer or its raw material monomer Before, it is necessary to avoid the technique of using the nanofiller as a dry powder as much as possible.

  A preferred first method is to disperse the surface-modified nanofiller obtained as described above in a predetermined organic solvent, prepare a nanofiller dispersion solution, and then add the nanofiller dispersion solution and the organic polymer. A target polymer nanocomposite is obtained by mixing and melt-kneading. As the kneader, a twin screw extruder, a vacuum microkneader extruder, a laboratory blast mill, or the like can be used.

  As a preferred second method, an organic polymer is dispersed and mixed in the nanofiller dispersion solution, and only the solvent is distilled off under high temperature and reduced pressure to obtain a target polymer nanocomposite.

  In both the first method and the second method, the organic solvent is a solvent that can dissolve the organic polymer, and preferably has a polarity close to that of the solvent in which the nanofiller is dispersed. It is done. For example, in the case of polycarbonate, tetrahydrofuran, chloroform, methylene chloride, 1,4-dioxane, cyclohexanone, 1,1,1-trichloroethane and the like can be mentioned.

  A preferred third method is a so-called solution polymerization method or melt polymerization method. The solution polymerization method is applied when a vinyl polymer such as acrylic resin or styrene resin is used as the organic polymer. In this case, the monomer of the organic polymer is dissolved in a nanofiller dispersion (optionally in the form of an organosol), the polymerization is advanced by a radical initiator, and after completion of the reaction, it is injected into a poor solvent. Polymer nanocomposites are deposited. For example, in the case of methyl methacrylate, polymer nanocomposites can be precipitated by radical polymerization in toluene and injection into hexane.

  The melt polymerization method can be applied when a condensation polymerization polymer is used as the organic polymer. In this case, a mixture containing a condensable monomer and a nanofiller dispersion (in some cases, in the form of an organosol) is heated while stirring under reduced pressure, and the condensation polymerization of the monomer proceeds while distilling off the solvent of the organosol. And the resulting polymerized by-product is removed to obtain a polymer nanocomposite. For example, in the case of polyethylene terephthalate, a nanocomposite can be obtained by mixing terephthalic acid, ethylene glycol, and nanofiller sol, and then distilling off the water generated by condensation with the solvent of the sol by stirring, heating, and vacuum distillation. .

  Examples are given below, but the present invention is not limited thereto.

Example 1.
1-1: Nanofiller modification / free modifier removal Nanofiller dispersion "IPA-ST" (isopropanol-dispersed silica sol, particle size 15nm, solid content 30%) manufactured by Nissan Chemical Industries, Ltd. Add 5 g of “KBM-402” (= γ-glycidoxypropylmethyldimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. as a quality agent, and mix at room temperature with stirring blades and a three-one motor (BL300R manufactured by HEIDON) at room temperature. Mixed for minutes. Thereafter, while continuing stirring, 0.2 g of triethylamine was diluted with isopropyl alcohol to a 10-fold amount, and then dropped, and the mixture was continuously mixed at 60 ° C. for 12 hours to sufficiently react the modifier. Next, the sol was transferred to an ultrafiltration device ("MOLSEP" FSlO-FUS1582 manufactured by Daisen Membrane Systems Co., Ltd .: membrane area 5m ² , manufactured by polyethersulfone, molecular weight cut off 150,000, length 1129mm x diameter 89mm) Unreacted modifier (free modifier) was washed. The solution was pumped to a filtration pressure of 1.6 kg / cm ^2, and pure isopropanol was fed to the outside of the membrane. Filtration was continued while returning the sol that passed without being filtered, and when the amount of the sol reached about 60 to 70% of the initial amount, pure isopropanol was added to maintain the concentration. The pure isopropanol used for washing was 8 L in total.

Solution ²⁹ Si-NMR before removal of free modifier (Figure 1), Solution ²⁹ Si-NMR after removal (Figure 2), CP / MAS solid ²⁹ Si-NMR after removal (Figure 3), and before removal the dispersion attach ultracentrifugation supernatant solution ²⁹ Si-MR chart (Figure 4). From FIG. 1, the peak of the modifier and the condensate can be seen before the removal of the modifier, and this has almost disappeared after the removal of FIG. However, it can be confirmed from the modifying group peak in FIG. 3 that the modifier is bound to the filler surface as intended. In order to confirm that most of the modifier is present for reference, the supernatant of the sample in Fig. 1 was collected and analyzed, and a sharp peak as shown in Fig. 4 was detected and confirmed. Was supported.

1-2: Composition (mixed solution)
After dissolving 85 g of polycarbonate “Novalex 7030A” (number average molecular weight 13000) made by Mitsubishi Engineering Plastics Co., Ltd. in 400 g of methylene chloride, add 50 g of nanofiller dispersion (solid content 30%) prepared in 1-1. The solvent was removed while gradually increasing the degree of vacuum, and finally, drying was performed at 100 ° C. under a reduced pressure of 10 mTorr or less for 4 hours, and further kneaded at 280 ° C. for 15 minutes to obtain a polymer nanocomposite. The ash content of the product was 14.5 wt%, and it was confirmed that almost all of the added silica was composited. This composition was colorless and had no yellowing, had a transparent appearance, and had a total light transmittance of 88% and a Haze value of 4% for the A light of a plate molded to a thickness of 1 mm. When the composite matrix polymer was analyzed by GPC, the number average molecular weight was 11,800, and the initial molecular weight was almost maintained.

Light transmittance measurement:
Method: ASTM D-1003 (Haze and Lumlnous Transmittace Of Transparent Plastics)
Equipment: HM-65 haze meter manufactured by Murakami Color Research Laboratory Measurement area: approx. 6mmφ, light source: halogen lamp 50W A light

Example 2
2-1: 600g of nanotech alumina / alcohol dispersion product (particle size 31nm, solid content 15%) manufactured by C-I Kasei Co., Ltd. was used as a nanofiller dispersion for nanofiller modification and free modifier removal. Add 5 g of “KBE-903” (= γ-aminoxypropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. and remove the free modifier by performing the same ultrafiltration operation as in Example 1-1. Thus, an isopropanol dispersion was obtained. It was confirmed by ²⁹ Si-NMR analysis of the dispersion that a sharp peak derived from the modifying agent present before removing the modifying agent was not detected.

2-2: Composition (melt polymerization)
Prepared in 2-1, by adding 18 mg (0.1 mmol) of zinc acetate as a catalyst to 124.1 g (2 mol) of ethylene glycol manufactured by Kanto Chemical Co., Ltd. and 194.2 g (1 mol) of dimethyl terephthalic acid manufactured by Kanto Chemical Co., Ltd. After adding 53 g of nano-filler dispersion (solid content 15%), gradually raising the degree of vacuum to 195 ° C to sufficiently remove the solvent and water generated, and proceeding with the transesterification, 280 Polymerization was carried out under reduced pressure of 3 mTorr or less at 3 ° C. for 3 hours, and this was further kneaded at 280 ° C. for 15 minutes to obtain a polymer nanocomposite. The product had an ash content of 3.9 wt%, and it was confirmed that almost all of the added alumina was composited. This composition was colorless and had no yellowing, had a transparent appearance, and had a total light transmittance of 84% and a Haze value of 6% for A light of a plate molded to a thickness of 1 mm.

Example 3
3-1: Nanofiller modification / removal of free modifier As a nanofiller, 5 g of “Nanotech Iron Oxide” manufactured by Cai Kasei Co., Ltd. was dispersed in 100 g of chloroform, and then Shinetsu Chemical Industry Co., Ltd. as a modifier. 1 g of “KBE-903” (= γ-aminoxypropyltriethoxysilane) manufactured by the method was added, and the free modifier was removed by performing the same ultrafiltration operation as in Example 1-1 to obtain a chloroform dispersion. It was. It was confirmed by ²⁹ Si-NMR analysis of the dispersion that a sharp peak derived from the modifying agent present before removing the modifying agent was not detected.

3-2: Composition (melt polymerization)
Kanto Chemical Co., Ltd. Bisphenol A 50.4g (221mmol), Kanto Chemical Co., Ltd. diphenyl carbonate 49.6g (232mmol), 100g of nanofiller dispersion (solid content 5%) prepared in 3-1, Add 5 mg of zinc oxide manufactured by Wako Pure Chemical Industries, Ltd. as a condensation polymerization catalyst, distill off chloroform with stirring blades and three-one motor (BL300R manufactured by HEIDON) in a nitrogen gas atmosphere, then heat to 160 ° C did. After confirming the melting of both monomer components, the temperature was raised to 230 ° C., the internal pressure was reduced to 30 kPa at this temperature, and stirring was continued for 1 hour. Subsequently, the temperature was increased and reduced to 250 ° C. and 3 kPa over 30 minutes, followed by stirring for 30 minutes. The temperature was further increased to 280 ° C. and 10 Pa, and the mixture was stirred at this temperature and reduced pressure for 30 minutes, then returned to normal pressure with nitrogen gas and allowed to cool. The obtained polymer nanocomposite had a pale yellow and almost transparent appearance. The total light transmittance of A light of a 2 mm thick plate was 85%, and the Haze value was 8%.

Example 4
4-1: Centrifugation removal of nano filler modification / release modifier In place of “IPA-ST” manufactured by Nissan Chemical Industries, Ltd. in Example 1-1, “MEK-ST” manufactured by the same company (methyl ethyl ketone dispersed silica sol, trimethylsilyl) The same as Example 1 except that 333g of several area% surface-treated product, particle size 15nm, solid content 30%) was used and 15g of "Hexamethyldisilazane" manufactured by Aldrich Co. was added as a modifier. Was performed.

4-2: Composition (solution polymerization)
Into 400 mL of toluene, add 100.1 g (1 mol) of methyl methacrylate manufactured by Kanto Chemical Co., Ltd. and 12.2 g (0.05 mol) of W-40 Pure Chemical Industries, Ltd. V-40 as a radical initiator, and prepare in 4-1. 150 g of the nanofiller dispersion liquid (30% in individual form) was added, the temperature was raised to 90 ° C. to initiate radical reaction, and polymerization was continued for 3 hours while stirring. After the reaction, the reaction solution was poured into 2 L of hexane, dried at 80 ° C. under a reduced pressure of 10 mTorr or less for 4 hours, and then kneaded at 200 ° C. for 15 minutes to obtain a polymer nanocomposite. The product had an ash content of 30.9 wt%, and it was confirmed that almost all of the added silica was composited. This composition was colorless and had no yellowing, had a transparent appearance, and had a total light transmittance of 87% and a Haze value of 3% for a plate formed to a thickness of 1 mm.

Example 5.
5-1: Nanofiller modification / release modifier Centrifugation removal Nanofiller dispersion of 600 nanograms of “Nanotech alumina / alcohol dispersion” (particle size 31 nm, solid content 15%) manufactured by Cai Kasei Co., Ltd. As a material, 5 g of “KBE-903” (= γ-aminoxypropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. was added, and instead of the ultrafiltration in Example 1-1, Mitsubishi Chemical Corporation In the nano particle decanter “Separation Plate Type Centrifugation DS-10V”, the centrifugal operation at the maximum capacity (7000 rpm) was performed for 1 H while discharging the solvent from the Investor Pump to a maximum of 450 cc in small amounts, and was discharged at this time. The operation of adding a new amount of isopropanol equal to the amount of the solvent was repeated three times to remove the free modifier, and an isopropanol dispersion was obtained.

5-2: Composition (solution mixing)
InChemCo. After dissolving 92.5 g of phenoxy resin "INCHEMREZ ^(R) Phenoxy PKFE" in 400 g of chloroform, add 50 g of nanofiller dispersion (solid content 15%) prepared in 5-1, while gradually increasing the degree of vacuum The solvent was removed, and finally the polymer nanocomposite was obtained by drying at 100 ° C. under reduced pressure of 10 mlbrr or less for 4 hours and further kneading at 220 ° C. for 15 minutes. The ash content of the product was 7.6 wt%, and it was confirmed that the added alumina was almost entirely composited. This composition was colorless and free from yellowing, had a transparent appearance, and had a total light transmittance of A light of 80% and a Haze value of 8% for a plate molded to a thickness of 1 mm.

Examples 6-14.
In place of “IPA-ST” manufactured by Nissan Chemical Industries, Ltd. in Example 1, the following modifications were made in the same manner as in Example 1 except for the following <Nano filler / dispersed solvent when removing modifier / solid content in composite>. The material removal operation and the composite operation were performed. Of these, since 6, 7 and 11 contained coarse particles, they were used after pulverization with a zirconia bead mill for 30 minutes after addition of the solvent.
6: Aluminum hydroxide <“Hijilite H42M” manufactured by Showa Denko KK / Methyl ethyl ketone / 2wt%>
7: Calcium carbonate <Calfine 500 by Maruo Calcium Co., Ltd./cyclohexanol/2wt%>
8: Titania <"Nanotech titania-toluene-dispersed crystals" / 5wt% manufactured by CI Kasei Co., Ltd.>
9: Cerium oxide <Nanotech Cerium Oxide-Toluene Dispersed Crystal / 5% by weight manufactured by CI Kasei Co., Ltd.>
10: Zinc oxide <Nanotech Zinc Oxide Silene Dispersion / 15 wt%, manufactured by CI Kasei Co., Ltd.>
11: Hydroxyabatite <Sangi Co., Ltd. "Hydroxyabatite" / Tetrahydrofuran / 5wt%>
12: Carbon <Nanomu Black / Toluene / 5wt% made by Frontier Carbon Co., Ltd.>
13: Gold <Tanaka Kikinzoku Kogyo Co., Ltd. "Gold citrate colloid solution" / 2wt%>
14: Silver <Nihon Paint Co., Ltd. “Silver Colloid Paste” / Tetrahydrofuran / 5wt%>

Comparative example

  In the comparative example, in the surface modification of the nanofiller in the above-described example, the same number is used for the case where the removal operation of the free modifier was not performed.

Comparative Example 1.
1-1: Nanofiller modification / release modifier residual nanofiller dispersion "IPA-ST" (isopropanol-dispersed silica sol, particle size 15 nm, solid content 30%) manufactured by Nissan Chemical Industries, Ltd. Add 5 g of “KBM-402” (= γ-glycidoxypropylmethyldimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd. as a quality agent, and stir at room temperature while stirring with a stirring blade and a three-one motor (BL300R manufactured by HEIDON). Mixed for minutes. Thereafter, while continuing stirring, 0.2 g of triethylamine was diluted with isopropyl alcohol to a 10-fold amount, and then dropped, and the mixture was continuously mixed at 60 ° C. for 12 hours to sufficiently react the modifier. This sol was used in the next step with the free modifier remaining.

1-2: Composition (mixed solution)
After dissolving 85 g of polycarbonate “Novalex 7030A” (number average molecular weight 13000) made by Mitsubishi Engineering Plastics Co., Ltd. in 400 g of methylene chloride, add 50 g of nanofiller dispersion (solid content 30%) prepared in 1-1. The solvent was removed while gradually increasing the degree of vacuum, and finally, drying was performed at 100 ° C. under a reduced pressure of 10 mTorr or less for 4 hours, and further kneaded at 280 ° C. for 15 minutes to obtain a polymer nanocomposite. The ash content of the product was 14.9 wt%, and it was confirmed that almost all of the added silica was composited. This composition was colored light brown by kneading at 280 ° C. and had a translucent appearance. The plate formed to a thickness of 1 mm had a total light transmittance of A of 71% and a Haze value of 34%. When the matrix polymer of the composite was analyzed by GPC, the number average molecular weight was 5700, which was greatly reduced from the initial molecular weight. The 1mm sample plate was not tough and could be easily broken by hand.

Comparative Examples 2 to 14.
Similarly, polymer nanocomposites were obtained in the same manner as in Examples 2 to 14, except that the nanofiller sol was used in the next step with the free modifier remaining. In these composites, the aggregation of nanofillers generally progressed and the transparency was poor, and most of the 1 mm sample plates were easily broken by hand.

  The data of the above examples and comparative examples are summarized in Table 1.

  As is apparent from Table 1, the polymer nanocomposite obtained according to the present invention contains almost no free modifier, and thus eliminates adverse effects such as aggregation of the free modifier and molecular weight reduction due to the free modifier. It can be seen that it is excellent in properties such as transparency and toughness.

  The present invention has been described in detail above with reference to specific examples. However, the present invention is not limited to the above contents, and various modifications and changes can be made without departing from the scope of the present invention.

  For example, the polymer nanocomposites of the present invention can optionally contain antioxidants and heat stabilizers (including, for example, hindered phenols, hydroquinones, thioethers, phosphites and their substitutions and combinations thereof), UV absorption. Agents (for example, resorcinol, salicylate, benzotriazole, benzophenone, etc.), lubricants, mold release agents (for example, silicon resin, montanic acid and salts thereof, stearic acid and salts thereof, stearyl alcohol, stearylamide, etc.), dyes (for example, nitrocin) , Coloring agents containing facials (for example, cadmium sulfide, phthalocyanine, etc.), additive additives (for example, silicon oil), crystal nucleating agents (for example, talc, kaolin, etc.), etc. can be added alone or in appropriate combination. .

In the surface modification method of the nano filler of the present invention, before the free modifier removal, is a graph showing an example of a ²⁹ Si-NMR chart of the surface modification solution. In the surface modification method of the nano filler of the present invention, after the free modifier removal, it is a graph showing an example of a ²⁹ Si-NMR chart of the surface modification solution. 6 is a graph showing an example of a CP / MAS solid ²⁹ Si-NMR chart of the surface modified solution after removing a free modifier in the nanofiller surface modifying method of the present invention. In the surface modification method of the nano filler of the present invention, before the free modifier removal, is a graph showing an example of a ²⁹ Si-NMR chart of the surface modification solution from ultracentrifugation was obtained supernatant.

Claims (16)

A step of dispersing the nanofiller in a solvent and adding a predetermined modifier to surface-modify,
Washing the solvent containing the nanofiller directly, removing the free modifier present as a residual component of the modifier in the solvent, and purifying;
A method for modifying the surface of a nanofiller, comprising:   The method for surface modification of a nanofiller according to claim 1, wherein the concentration of the nanofiller in the solvent is substantially the same before and after the direct washing of the solvent.   The method for surface modification of a nanofiller according to claim 1 or 2, wherein the direct washing of the solvent is performed using at least one of ultrafiltration and centrifugation.   The method for modifying a surface of a nanofiller according to any one of claims 1 to 3, wherein the modifier is at least one of a silane coupling agent and a silylating agent. The method for modifying the surface of a nanofiller according to claim 4, wherein the residual state of the free modifier is controlled by the peak intensity in ²⁹ Si-NMR.   The nano filler is selected from the group consisting of silica, alumina, aluminum hydroxide, calcium carbonate, titania, iron oxide, cerium oxide, zinc oxide, hydroxyapatite, carbon, gold, silver and mixtures thereof, and has a major axis of 2 to 200 nm. It is a nanoparticle, The surface modification method of the nano filler as described in any one of Claims 1-5 characterized by the above-mentioned.   The said nano filler is used in the state of organosol, The surface modification method of the nano filler as described in any one of Claims 1-6 characterized by the above-mentioned.   The method for surface modification of a nanofiller according to claim 7, wherein the surface modification is performed in a solvent constituting the organosol.   A polymer nanocomposite comprising a surface-modified nanofiller obtained by the method according to claim 1 and an organic polymer.   The polymer nanocomposite according to claim 9, wherein the polymer nanocomposite is substantially free of the free modifier.   The polymer nanocomposite according to claim 9 or 10, wherein the organic polymer is a transparent resin having a light transmittance of 80% or more.   The polymer nanocomposite according to claim 11, wherein the organic polymer is at least one selected from the group consisting of an acrylic resin, a polyester resin, and a polycarbonate resin.   The polymer nanocomposite according to any one of claims 9 to 12, wherein the content of the surface-modified nanofiller is 0.2 wt% to 60 wt% as a solid content. It is a manufacturing method of the polymer nanocomposite as described in any one of Claims 9-13,
Dispersing the surface-modified nanofiller in a predetermined organic solvent to produce a nanofiller dispersion solution;
Mixing the nanofiller dispersion solution and the organic polymer, and obtaining the polymer nanocomposite by melt-kneading;
A method for producing a polymer nanocomposite, comprising: It is a manufacturing method of the polymer nanocomposite as described in any one of Claims 9-13,
A step of dispersing the nanofiller in a predetermined organic solvent to prepare a nanofiller dispersion solution;
Dispersing and mixing the organic polymer in the nanofiller dispersion solution, distilling off only the solvent under high temperature and reduced pressure, and obtaining the polymer nanocomposite;
A method for producing a polymer nanocomposite, comprising: It is a manufacturing method of the polymer nanocomposite as described in any one of Claims 9-13,
A step of dispersing the nanofiller in a predetermined organic solvent to prepare a nanofiller dispersion solution;
Mixing the nanofiller dispersion solution and the monomer of the organic polymer, and polymerizing the monomer to obtain the polymer nanocomposite;
A method for producing a polymer nanocomposite, comprising:

Images