WO2008068874A1

WO2008068874A1 - Particulates and the manufacturing methods for them

Info

Publication number: WO2008068874A1
Application number: PCT/JP2006/324987
Authority: WO
Inventors: Kazufumi Ogawa
Original assignee: Kazufumi Ogawa
Priority date: 2006-12-08
Filing date: 2006-12-08
Publication date: 2008-06-12

Abstract

Many types of particulates with electrical and other capabilities have been developed and manufactured; none of them have incorporated the idea of adding new capabilities to the original capabilities without losing the shape of the particulates. Particulates are dispersed into a chemical absorbent produced by mixing a chlorosilane compound with a nonaqueous organic solvent to allow the said chlorosilane compound to react with the surfaces of the said particulates. This process produces films consisting of molecules formed on the surfaces as covalent bonds, making it possible to provide particulates with the capability of improving dispersibility into solvents and other reactivity capabilities while maintaining the original capabilities of the particulates.

Description

DESCRIPTION

PARTICULATES AND THE MANUFACTURING METHODS FOR THEM

BACKGROUND OF THE INVENTION

Field of the Invention

The , inventions are associated with high-performance particulates.

Specifically, they are related to inorganic particulates that consist of a metal or metal oxide the surfaces of which are stabilized, or provided with thermal/light reactivity or radical/ion reactivity; organic particulates that consist of high polymers or polymeric micelles; and organic-inorganic hybrid particulates.

The "inorganic particulates," covered by the inventions include particulates of conductors, semiconductors, insulators, magnetic substances, fluors, light absorbing subsutances, light transmitting substances, and pigments. The "organic particulates," include particulates of organic fluors, organic light absorptive substances, organic light transmitting substances, organic pigments, and drugs. The "organic-inorganic hybrid particulates," include particulates of drugs for the DDS (Drug Delivery System), cosmetics, and organic-inorganic hybrid pigments.

Description of Related Art There are many known approaches to adding surface-active agents to mixtures of particulates and solvents to improve the particulate dispersibility into solutions.

However, no new particulates along with manufacturing processes for them have been developed or provided that have capabilities added to them, without loss of the original capabilities of theirs, by covering the particulates with organic films (e.g. functional monomolecular films) chemically absorbed (as covalent bonds) onto the surfaces of the particulates themselves.

Many particulates that have electrical, magnetic, light, and other capabilities have been developed and produced. However, these particulate do not include the idea of adding new capabilities to their original capabilities with virtually maintaining the shapes of particulates.

The inventions aim to provide particulates with additional capabilities that inactivate their surfaces and improve dispersibility into solvents and many other reactivity capabilities while virtually maintaining the original shapes and capabilities by covering the surfaces of particulates with organic thin coatings (e.g. functional monomolecular films that include capability functional groups such as inert or reactive functional groups with critical surface energy of 25 mN/m or less).

SUMMARY OF THE INVENTION ,

The first invention provided as a means to solve the problem mentioned above, is particulates characterized by how they are covered with organic thin coatings formed on the surfaces as covalent bonds.

The second invention is particulates characterized by how they consist of molecules that allow the organic thin coatings formed with the first invention as covalent bonds on the surfaces to include functional groups at one end and to form covalent bonds through Si or S at the other end on the surfaces of the particulates. The third invention is particulates characterized by their functional groups described in the second invention are inert or reactive groups with critical surface ^< energy, of 25 mN/m or less.

The fourth invention is particulates characterized by their inert groups with critical surface energy of 25 mN/m or less described in the third invention include - CF₃ and/or - CH₃.

The fifth invention is particulates characterized by their reactive functional groups as thermal/light reactive or radical/ion reactive functional groups. The sixth invention is particulates characterized by their reactive functional groups described in the fourth invention are epoxy, imino, or carconyl groups. The seventh invention is particulates characterized by their organic thin coatings formed on the surfaces as covalent bonds as described in the first and the second invention consist of monomolecular films.

The eighth invention is a method for manufacturing particulates characterized by including at least a process for dispersing particulates into a chemical absorptive liquid produced by mixing a chlorosilane compound with a nonaqueous organic solvent in order to allow the said chlorosilane compound to react with the particulate surfaces. The ninth invention is a method for manufacturing particulates characterized by including at least a process for dispersing particulates into a chemical absorptive liquid produced by mixing an alkoxysilane compound, silanol condensation catalyst, and nonaqueous organic solvent in order to allow the alkoxysilane compound to react with the particulate surfaces.

The tenth invention is a method for manufacturing particulates characterized by including at least a process for dispersing particulates into a chemical absorptive liquid to allow a chlorosilane or alkoxysilane compound to react with the particulate surfaces as described in the eighth and ninth inventions, followed by a process for cleaning the particulate surfaces with an organic solvent to allow monomolecular films to form on the surfaces of particulates as covalent bonds.

The eleventh invention is a method for manufacturing particulates characterized by its use of a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or amino alkyl alkoxysilane compound in place of the silanol condensation catalyst described in the ninth invention.

The twelfth invention is a method for manufacturing particulates characterized by the silanol condensation catalyst described in the ninth invention is mixed with at least one substance selected among a ketimine compound, organic acid, or aldimine compound, enamine compound, oxazolidine compound, or amino alkyj alkoxysilane compound as a promoter. The inventions are outlined below.

The inventions aim to provide particulates covered with organic thin coatings formed on the surfaces as covalent bonds through a process for dispersing particulates into a chemical absorptive liquid produced by mixing a chlorosilane compound with a nonaqueous organic solvent to allow the mentioned chlorosilane compound to react with the surfaces of the said particulates or a process for dispersing particulates into a chemical absorptive liquid produced by mixing an alkoxysilane compound, silanol condensation catalyst, and nonaqueous organic solvent to allow the alkoxysilane compound to react with the particulate surfaces. It is convenient if the organic films formed on the surfaces as covalent bonds include functional groups at one end and consist of molecules that form covalent bonds through Si or S at the other end because capabilities can be added without loss of the stability of particulates. In addition, if the functional groups are inert or reactive groups with critical surface energy of 25 mN/m or less, then it is easy to add dispersibility or reactivity to particulates.

In order to achieve critical surface energy of 25 mN/m or less, - CF₃ and/or - CH3 can be used as inert groups. In addition, reactivity is conveniently added to particulates if the reactive functional groups are thermal/light reactive or radical/ion reactive groups.

Practical usable reactive functional groups include epoxy, imino, and carconyl groups, which produce covalent bonds. In addition, it is convenient if the organic thin coatings formed on the surfaces as covalent bonds consist of monomolecular films because the shape of the particulate surfaces is maintained.

Furthermore, if particulates are dispersed into a chemical absorptive liquid to allow a chlorosilane or alkoxysilane compound to react with particulate surfaces, followed by a process for cleaning particulate surfaces with an organic solvent to form monomolecular films on the surfaces as covalent bonds, then monomolecular films are conveniently formed at a low cost.

Besides, if a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or amino alkyl alkoxysilane compound is used in place of the silanol condensation catalyst, then the processing time is conveniently reduced.

Furthermore, if the silanol condensation catalyst is mixed with at least one substance selected among a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, and amino alkyl alkoxysilane compound as a promoter, the processing time is further reduced.

As described above, the inventions have the effect of stabilizing particulates while virtually maintaining the original capabilities of particulates, improving the dispersibility into solvents, and providing particulates with reactive capabilities added to them. In addition, covering particulates with chemically absorbed monomolecular films provides the capabilities of stabilizing them while maintaining their original shape and capabilities and improving dispersiblity along with the effect of providing particulates with chemical reaction capabilities added to them. BRIEF DESCRIPTION OF THE DRAWINGS

Figs. 1 A and 1 B show the particulate surfaces before the reaction occurs and after monomolecular films are formed, respectively. The figures are conceptual drawings that indicate the particulate reactions in Implementation Example 1 enlarged to the molecular level; and

Figs. 2A and 2B show the particulate surfaces before the reaction occurs and after monomolecular films containing epoxy groups are formed, respectively. Fig. 2

C shows the particulate surfaces after monomolecular films containing amino groups are formed. The figures are conceptual drawings that indicate the particulate reactions in Implementation Example 2 enlarged to the molecular level.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The inventions provide particulates that have molecules formed on the particulate surfaces as covalent bonds have reactive functional groups (e.g. thermal/light reactive or radical/ion reactive functional groups) and monomolecular films formed by using at least a process for dispersing particulates into a chemical absorptive liquid produced by mixing a chlorosilane compound with a nonaqueous organic solvent to allow the chlorosilane compound to react with particulates surfaces, followed by a process for cleaning particulates with an organic solvent, or at least a process for dispersing particulates into a chemical absorptive liquid produced by mixing an alkoxysilane compound, silanol condensation catalyst, and nonaqueous organic solvent to allow the alkoxysilane compound to react with particulate surfaces, followed by a process for cleaning the surfaces with an organic solvent. For this reason, the inventions have the capabilities of stabilizing the surfaces of particulates themselves while virtually maintaining the original shape and capabilities of particulates, improving dispersibility, and providing particulates with many chemical reaction capabilities added to them.

Here, implementation examples are used to detail the inventions, which will not limit the, inventions.

Particulates related to the inventions include the particulates of conductors, semiconductors, insulators, magnetic substances, fluors, light absorptive substances, light transmitting substances, pigments, drugs, cosmetics, abrasives, and anti-abrasion materials that include hydrophilic oxides on their surfaces. First, lead oxides, which are pigment particulates, are explained as an example. [Implementation Example 1] First, lead oxide particulates 1 with an average diameter of 100 nm or so were prepared (Figure 1 ) and then well dried. Then, a chemical absorbent (e.g. CF₃ (CF₂)₇(CH₂)₂SiCl₃) that contains carbon fluoride groups (functional site) and chlorosilane groups (active site) that exhibit critical surface energy of 25 mN/m or less with formation of monomolecular films was dissolved in a nonaqueous organic solvent (e.g. dewatered nonane) in a concentration of 0.1 weight percent or so to produce a chemical absorptive solution (hereafter referred to as the absorptive solution). When the described lead oxide particulates were immersed into this absorptive solution and agitation reacted in a dry atmosphere (a relative humidity of 30% or less was preferable), the surfaces of the lead oxide particulates 1 included many hydroxyl groups (see Figure 1A). As a result, chlorosilyl groups (SiCI) contained in the described chemical absorbent reacted with the hydroxyl groups (OH) on the_^ said particulate surfaces, which caused a dehydrochlorination reaction, generating bonds shown by the expression below (Chemical Expression 1 ) all over the surfaces of the lead oxide particulates. Then, a CFC-family solvent was added and agitation cleaning was performed. This produced lead oxide particulate 4 covered with monomolecular films 3 consisting of the chemical absorbent mentioned above. [Chemical Expression 1]

O—

CF₃(CF₂)7(CH₂)2Si — O — O—

Since the monomolecular films formed on the particulate surfaces have critical surface energy of 6 mN/m or so, these pigment particulates are easily dispersed into CFC- and silicon-family solvents and fluorine resins with low critical surface energy, producing extremely high-quality paint.

These chemical absorptive films were formed on the particulate surfaces as extremely strong covalent bonds, which were not removed through normal reactions. In addition, since the thickness of the film is only that of one molecular (approximately 1 nm), the surface shape of the particulates were not virtually compromised or no change in color was seen even if particulates with diameters of a few tens of nanometers or so (nanoparticles) were used.

When the particulates were taken out into air without cleaning, the dispersity remained almost the same and the solvent vaporized; the chemical absorbent that remained on the particulate surfaces reacted with moisture in air, generating particulates that had very thin chemical absorptive polymer films consisting of the said chemical absorbent formed on the particulate surfaces.

The implementation example above used as the chemical absorbent a drug containing carbon fluoride family functional groups in its functional site that have the effect of reducing surface energy. When a drug containing carbon hydride groups (- CH₃ groups) in its functional site (e.g. CH₃(CF2)7(CH₂)2SiCI₃), was used, coatings with critical surface energy of about 25 mN/m were generated. When these drugs were arbitrarily mixed, the critical surface energy of the coatings on the particulate surfaces could be controlled at will within the range from 6 to 25 mN/m. It goes without saying that it is possible to manufacture particulates with new capabilities added to them and the surface energy controlled to a desired value without loss of the original shape of the particulates by changing the functional groups to different ones.

Since this method produces hydrochloric acid when coatings are formed, particulate surfaces may be scratched to some extent. However, Implementation Example 1 showed very few scratches, presenting no problem. Particulates thus covered with monomolecular films (e.g. particulates covered with hydrocarbon-family monomolecular films with critical surface energy of 25 mN/m or so) had the capability of suppressing cohesion and dispersed into hydrocarbon-family solvents and acryl-family plastics.

In addition, the surfaces were inactivated and protected from air, and therefore prevented from oxidizing even for metal nanoparticulates that are likely to react with oxygen.

Implementation Example 1 above used CF₃(CF₂)₇(CH₂)2SiCI₃ as the carbon ^■ fluoride family chemical absorbent. Besides this, substances (1) to (12) listed below, including hydrocarbon-family substances, could be used. (1 ) CF₃CH₂O(CH₂)₁₅SiCl3 (2) CF₃(CH₂)₃Si(CH3)2(CH₂)₁₅SiCl3 (3) CF3(CF2)5(CH₂)₂Si(CH3)2(CH₂)9SiCl3 (4) CF₃(CF₂)7(CH₂)2Si(CH3)2(CH₂)9SiCl3

(5) CF₃COO(CH₂)I₅SiCI₃

(6) CF₃(CF₂)₅(CH₂)₂SiCI₃

(7) CH₃CH₂O(CH₂)₁₅SiCI₃ (8) CH₃(CH₂)3Si(CH3)2(CH₂)i5SiCl3 (9) CH₃(CH₂)₅Si(CH₃)₂(CH₂)₉SiCI₃ (10) CH₃(CH2)7Si(CH3)2(CH₂)₉SiCl3 (11) CH₃COO(CH₂)₁₅SiCI₃ (12) CH₃(CH₂)₉SiCI₃ For particulates of Au, when a drug (e.g. H₃C(CH₂)n-SH and H₃C(CH₂)₃-SH) that included - SH groups or triazine thiol groups as a replacement of the SiCI3 , groups at the end was used, Au particulates that had monomolecular films formed through S were manufactured. On the other hand, when a drug that had - SH groups and methoxyethyl groups at both ends (e.g. HS(CH₂)₃Si(OCH₃)₃) was used, Au particulate that had monomolecular films containing methoxyethyl formed on the surfaces were manufactured. Furthermore, this approach enabled Au particulates to form covalent bonds with conductors, semiconductors, insulators, magnetic substances, fluors, light absorptive substances, light transmitting substances, pigments, medicinal substances, cosmetic materials, abrasives, anti-abrasion materials (the shapes are not limited, same effect for particulates), and other materials that contain a hydrophilic oxide or hydroxide on the surfaces through -S ... Si- groups; the surfaces of the materials mentioned above were successfully covered with Au. [Implementation Example 2] First, anhydrous cerium oxide particulates 11 were produced and well dried.

Then, a chemical absorbent was produced by measuring a drug that includes reactive functional groups (e.g. epoxy and imino groups) and alkoxysilane groups at the other end in its functional site (e.g. drugs shown by Chemical Expression 2 or 3 shown below) and dibutyltin diacetyl acetonate or acetic acid, which is an organic acid, as a silanol condenation catalyst so that the former would be 99 weight percent and the latter one weight percent, and then dissolving them in a solvent (e.g. a solution of 50% hexamethyldisiloxane and 50% dimethyl formamide) produced by mixing the same amounts of silicon and dimethyl formamide so that the concentration would be one- weight percent or so (preferable concentrations are about 0.5 - 3%). [Chemical Expression 2]

O OCH₃

CH₂-CHCH₂O(CH₂)SSi -OCH₃

OCH₃

[Chemical Expression 3]

OCH₃

H₂N(CH₂)₃Si —OCH₃ OCH₃

Particulates of anhydrous cerium oxide were mixed into this absorptive liquid and agitated, then allowed to react with the liquid for about two hours in. normal air (with a relative humidity of 45%). Because the particulate surfaces of the anhydrous cerium oxide include many hydroxyl groups 12 (Figure 2A), the - Si (OCH₃) groups in the chemical absorbent and hydroxyl groups mentioned above undergo a dealcoholization reaction (de-CH₃OH in this case) with existence of the silanol condensation catalyst or acetic acid, which is an organic acid, forming bonds as shown by Chemical Expression 4 or 5 below, producing chemical absorptive monomolecular films 13 that include epoxy groups or chemical absorptive films 14 that include amino groups with a film thickness of about 1 nanometer formed as chemical bonds all over the particulate surfaces (Figures 2B and 2C).

When an absorbent that includes amino groups is used, sedimentation occurs for tin-family catalysts; acetic acid or any other organic acid should have been used. Amino groups include imino groups. Other substances that include imino groups are absorbents such as pyrrole and imidazole erivatives. In addition, when a ketimine derivative absorbent was used, amino groups were easily introduced through hydrolytic degradation after the film formation.

Then, a chlorine-family solvent (e.g. trichloroethylene) was added and agitated, and cleaned several times. As with Implementation Example 1 , this produced on the surfaces cerium oxide covered with chemical absorptive monomolecular films that have reactive functional groups (e.g. epoxy and amino groups). [Chemical Expression 4]

O O—

CH₂-CHCH₂O(CH₂)SSi — O—

O—

[Chemical Expression 5]

O—

H₂N(CH₂J₃Si -O- O—

As with Implementation Example 1 , this processing area also had extremely thin coatings with a thickness of a few nanometers, which did not compromise the diameter and surface shape of the particulate.

When they were taken out into air without cleaning, the reactivity remained almost the same; the solvent vaporized and the chemical absorbent that remained on the particulate surfaces reacted with moisture in air, producing particulates that had very thin polymer coatings consisting of the said chemical absorbent formed on the particulate surfaces.

This approach that uses alkoxysilane derivatives is characterized by requiring no dry atmosphere and excels in mass productivity unlike Implementation

Example 1 , which uses chloro silyl derivatives. In addition, because the approach uses a dealcoholization reaction instead of a dehydrochlorination reaction, it can be used even for organic and inorganic substances the particulates of which are destroyed by hydrochloric acid, providing a wider range of applications.

Then, the same amounts of cerium oxide particulates covered with chemical absorptive monomolecular films that have the epoxy or amino groups mentioned above were taken out and well mixed with each other and heated to about 50 - 60⁰C in a mold. This allowed the epoxy and amino groups to be added to the particulates through the reaction as shown by the expression below (Chemical Expression 6), which combined and solidified the particulates, producing a whetstone that did not include any binder resins at all. In addition, an adequate amount of imidazole, which is a cross linking agent, was added to the serium oxide particulates covered with chemical absorptive monomolecular films that have epoxy groups, and the mixture was well mixed and heated to 50 - 60⁰C in a mold. This cross linked the epoxy groups on the particulate surfaces, and combined and solidified them, producing a whetstone that did not include any binder resins at all. Furthermore, this mixture was dispersed into an organic solvent, and was put on the surface of a metal disc, which was then heated. This produced a cutting whetstone that included no binder resin. [Chemical Expression 6]

O

/ \ -(CH₂)CH-CH₂ + H₂NCH₂ —

► - (CH₂)CHCH₂-NHCH₂ -

OH

Implementation Example 2 above used the substance shown by Chemical

Expression 2 or 3 as the chemical absorbent that includes reactive groups. Besides these, the substances shown by (21 ) to (36) listed below were usable.

(21) (CH₂OCH)CH₂O(CH₂)7Si(OCH3)3

(22) (CH₂OCH)CH2θ(CH2)iiSi(OCH₃)3

(23) (CH₂CHOCH(CH₂)2)CH(CH2)2Si(OCH3)3

(24) (CH₂CHOCH(CH₂)₂)CH(CH₂)₄Si(OCH₃)₃ (25) (CH₂CHOCH(CH₂)2)CH(CH2)6Si(OCH₃)3

(26) (CH₂OCH)CH₂O(CH₂)7Si(OC₂H5)3

(2Z) (CH₂OCH)CH₂O(CH₂)HSi(OC₂Hs)₃ (28) (CH2CHOCH(CH₂)2)CH(CH2)2Si(OC₂H₅)3 (29) (CH2CHOCH(CH2)2)CH(CH₂)4Si(OC₂H5)3 (30) (CH₂CHOCH(CH₂)₂)CH(CH₂)₆Si(OC₂H₅)₃

(31 ) H₂N(CH2)5Si(OCH₃)3 (32) H₂N(CH₂)7Si(OCH₃)3

(33) H₂N(CH2)9Si(OCH₃)3

(34) H₂N(CH₂)SSi(OC₂Hs)₃

(35) H₂N(CH₂)TSi(OC₂Hs)₃

(36) H₂N(CH₂J₉Si(OC₂Hs)₃ Here, the (CH₂OCH)- and (CH₂CHOCH(CH₂) ₂)CH- groups represent the functional groups represented by Chemical Expressions 7 and 8 below, respectively. When particulates are made of Au and a drug that has Si(OCH₃) ₃at the end replaced with -SH groups or triazine thiol groups (e.g. H₂N(CH₂)n-SH and H₂N(CH₂)₂-SH) was used, Au particulates with functional monomolecular films formed through S were produced.

[Chemical Expression 7]

O CH₂-CH -

[Chemical Expression 8]

0 CH-CH₂

\ / \

CH CH

\ /

CH₂ -CH₂

In addition, the substances shown in (41) - (46) below were usable as chemical absorbents that include energy beam (e.g. light and electron radiations) reactive functional groups: (41 ) CH ≡ C - C ≡ (CH₂)₁₅SiCI₃ (42) CH ≡ C - C ≡ C - (CH₂)2Si(CH3)2(CH₂)i5SiCl3

(43) CH ≡ C - C ≡ C - (CHa)₂Si(CHa)₂(CH₂)QSiCI₃ (44) (C6H₅)(CH)₂CO(C6H4)O(CH₂)₆OSi(OCH3)3 (45) (C6H₅)(CH)₂CO(C6H4)O(CH₂)₆OSi(OC2H₅)3 (46) (C6H₅)CO(CH)₂(C6H4)O(CH₂)6OSi(OCH3)₃

Here, (CeHs)CO(CH) ₂ (C₆H₄) represents carconyl groups. The particulates covered with these films formed as they are or formed films; they were cured when they were only exposed to ultraviolet rays.

In Implementation Example 2, carboxylic metal salt, carboxylic ester metal salt, carboxylic metal salt polymer, carboxylic metal salt chelate, ester titanate, and ester chelate titanate families can be used as the silanol condensation catalyst. More specifically, the following substances were usable: stannous acetate, dibutyltin laurate, dibutyltin dioctate, dibutyltin diacetate, dioctyltin Laurate, dioctyltin dioctate, dioctyltin diacetate, stannous dioctane acid, lead naphthenate, cobalt naphthenate, iron 2-ethylhexoate, dioctyltin bis octylthio glycolate acid ester salt, dioctyltin ester salt maleate, didutyltin maleic acid salt polymer, dimethyltin mercapto- propione acid salt polymer, didutyltin bis acetylacetate, dioctyltin bis acetyl Laurate, tetrabutyl titanate, tetranonyl titanate, and bis (acetylacetonyl) depropyl tintanate.

As solvents for forming films, usable were organic chlorine family solvents, carbon hydride family solvents, and silicon family solvents that contain no water or mixtures of any of them for alkoxysilane- or chlorosilane-family chemical absorbents. If the concentration of particulates is increased by vaporizing the solvent without performing cleaning, then the solvent should desirably have a boiling point between of about 50 - 250⁰C. When the absorbent is made of an alkoxysilane family substance and organic films are formed by vaporizing the solvent, then methanol, ethanol, propanol, and other alcohols or mixtures of them were usable in addition to the solvents above mentioned.

More specifically, usable were organic chlorine family solvents, nonaqueous petroleum naphtha, solvent naphtha, petroleum ether, petroleum benzin, isoparaffin, normal paraffin, decalin, industrial gasoline, nonane, decane, kerosene, dimethylsilicon, phenylesilicon, alkyl degeneration silicon, polyether silicon, and dimethylformamide, for example.

Carbon fluoride family solvents include CFC family solvents, Fluorinert (from 3M), and Aflude (from Asahi Glass). These solvents can be used alone or two or more solvents can be mixed if they mix well with each other. In addition, chloroform or any other organic chlorine family solvent may be added.

On the other hand, when a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or amino alkyl alkoxysilane compound was used in place of the above mentioned silanol condensation catalyst, the processing time was reduced to about 1/2 or 2/3 of the original time even if the concentration was the same.

Furthermore, when the silanol condensation catalyst was mixed with a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or amino alkyl alkoxysilane compound (while the mixture ratio could be from 1 :9 to 9:1 , the desirable ratio is normally 1 :1 or so), the processing time was further sped up (to about 30 minutes), reducing the time required for producing films to a fraction of the original time.

For example, dibutyltin oxide, which is a silanol condensation catalyst, was replaced with H3 from Japan Epoxy Resins, which is a ketimine compound, without changing the other conditions; the result was almost the same except that the reaction time was reduced to about one hour.

Furthermore, the silanol catalyst was replaced with a mixture of H3 from Japan Epoxy Resins and dibutyltin bis acetylacetate, which is a silanol catalyst, (with a mixture ratio of 1 :1 ) without changing the other conditions; the result was almost the same except that the reaction time was reduced to about 30 minutes. These results revealed that ketimine compounds and organic acids, aldimine compounds, enamine compounds, oxazolidine compounds, and amino alkyl alkoxysilane compounds are more active than the silanol condensation catalyst.

They also indicated that a mixture of the silanol condensation catalyst and any of ketimine compounds, organic acids, aldimine compounds, enamine compounds, oxazolidine compounds, and amino alkyl alkoxysilane compounds provides higher reactivity.

The usable ketimine compounds are not limited in particular; they include 2, 5, 8 - triaza -1 , 8 - nonadiene; 3, 11 - dimethyl - 4, 7, 10 - triaza - 3, 10 - tridecadien; 2,

10 - dimethyl - 3, 6, 9 - triaza - 2, 9 - undecadien; 2, 4, 12, 14 - tetramethyl - 5, 8,

11 - triaza - 4, 11 - pentadecadien; 2, 4, 15, 17 - tetramethyl -5, 8, 11 , 14 - tetraaza - 4, 14 - octadecadien; and 2, 4, 20, 22 - tetramethyl - 5, 12, 19 - triaza - 4, 19 - trieicosadien.

The usable organic acids are not limited in particular; they include formic acid, acetic acid, propionic acid, butyric acid, and malonic acid, which all produced almost the same effect.

While the two implementation examples used sodium oxide and cerium oxide particulates, the inventions can apply to any particulates if they include active hydrogen, i.e. hydrogen in hydroxyl groups or hydrogen in amino or imino groups, on their surfaces.

Specifically, they can apply to "inorganic particulates," such as the particulates of conductors, semiconductors, insulators, magnetic substances, fluors, light absorbing substances, light transmitting substances, and pigments; "organic particulates," such as the particulates of organic fluors, organic light absorbing substances, organic light transmitting substances, organic pigments, and drugs; and "organic-inorganic hybrid particulates," such as the particulates of drugs for the DDS (Drug Delivery System), cosmetics, and organic-inorganic hybrid pigments.

Claims

1. Particulates characterized by how they are covered with organic thin coatings formed on their surfaces as covalent bonds.

2. Particulates described in Claim 1 characterized by the organic films formed on their surfaces as covalent bonds include at one end capability functional groups and at the other end consist of molecules that form covalent bonds on the particulate surfaces through Si or S.

3. Particulates described in Claim 2 characterized by their capability functional groups are inert groups or reactive functional groups with critical surface energy of 25 mN/m or less.

4. Particulates described in Claim 3 characterized by their inert groups with critical surface energy of 25 mN/m or less include - CF₃ and/or - CH₃.

5. Particulates described in Claim 3 characterized by their reactive functional groups are heat/light reactive or radical/ion reactive.

6. Particulates described in Claim 4 characterized by their reactive functional groups are epoxy, imino, or carconyl groups.

7. Particulates described in Claims 1 and 2 characterized by organic thin coatings formed on the surfaces as covalent bonds consist of monomolecular films.

8. A method for manufacturing particulates characterized by including at least a process for dispersing particulates into a chemical adsorptive liquid produced by mixing a chlorosilane compound with a nonaqueous organic solvent to allow the mentioned chlorosilane compound to react with the surfaces of the said particulates.

9. A method for manufacturing particulates characterized by including at least a process for dispersing particulates into a chemical adsorptive liquid produced by mixing an alkoxysilane compound, silanol condensation catalyst, and nonaqueous organic solvent to allow the alkoxysilane compound to react with the particulate surfaces.

10. A method for manufacturing particulates described in Claims 8 and 9 characterized by a process for dispersing particulates into an chemical absorptive liquid to allow a chlorosilane or an alkoxysilane compound to react with the particulate surfaces, followed by a process for forming monomolecular films on the particulate surfaces as covalent bonds after cleaning the surfaces with an organic solvent.

11. A method for manufacturing particulates described in Claim 9 characterized by its uses of a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, or amino alkyl alkoxysilane compound in place of a silanol condensation catalyst.

12. A method for manufacturing particulates described in Claim 9 characterized by its use of at least one promoter chosen among a ketimine compound, organic acid, aldimine compound, enamine compound, oxazolidine compound, and amino alkyl alkoxysilane compound mixed with a silanol condensation catalyst.