JPH0477686B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing surface-modified silica composite oxide powder. [Prior art and problems to be solved by the invention] The mechanical strength of a material composed of an inorganic oxide powder and an organic polymer is determined by the strength of the organic polymer as a continuous phase and the inorganic oxide powder as a dispersed phase. It is greatly influenced by the interface state. However, since the surface of inorganic oxide powder is generally hydrophilic, it has poor affinity with organic polymers. Therefore, it is common practice to hydrophobically modify the surface of inorganic oxide powder. Surfactants, silane coupling agents, and the like have conventionally been used for this surface modification, and it is widely known that silane coupling agents are particularly effective in modifying the surface of silica powder. However, materials filled with powder whose surface has been treated with a silane coupling agent have a problem with their durability in water. For example, EP Prudemann in his book ``Silane Coupling Agents'' shows that the strength of materials made of silica and wired polymers surface-treated with silane coupling agents is significantly reduced by boiling in water. In particular, the above problem is serious for materials such as dental materials that are inserted into tooth cavities for the treatment of cavities and are used in the oral cavity for a long period of time. In Journal of Dental Research, 61 (12), 1982, GM Brauer et al. treated ultrafine silica particles (specific surface area 150 m ² /g) with silane coupling under an amine catalyst and used the powder to develop dental materials. is being prepared. They report that although the initial strength is improved by amine catalysts, it decreases over time due to thermal cycles using hot and cold water. Therefore, improving the durability of the interface between an inorganic oxide powder treated with a silane coupling agent and an organic polymer has become an important technical issue that needs to be solved. [Means for Solving the Problem] The present inventors have conducted extensive research on materials in which inorganic oxide powder is dispersed in organic polymers, with the aim of improving the decrease in mechanical strength caused by immersion in water. . As a result, it has been found that the above problems can be solved by surface-modifying an inorganic oxide powder having a specific surface property using a specific method. That is, the present invention focuses on the strength (pKa) of surface acid sites.
A silica composite oxide powder, which is characterized in that a silica composite oxide powder whose value is in the range from −3.0 to 3.3 is treated with a primary or secondary aliphatic amine and reacted with a silane coupling agent. It is a method of manufacturing the body. The inorganic oxide powder used in the present invention has a surface acid site whose acid strength (hereinafter expressed in pKa) is higher than −3.0.
In the range below 3.3, preferably higher than 0.8
It is a silica composite oxide powder in the range of 3.3 or less. If the pKa value is -3.0 or less, that is, if the acid strength is high, the polymerization catalyst contained in the composite material mixed with an organic polymer may react with the powder surface and develop color, which is not preferable. Also, the pKa value is 3.3
If the acid strength is higher, that is, the acid strength is lower, the mechanical strength of the composite material decreases due to immersion in water, and the effects of the present invention are not fully exhibited. Although the reasons for this are still unclear, it is thought that when the acid strength is low, aliphatic amines have little interaction with the surface of the inorganic oxide powder, and are unable to exhibit sufficient effects as catalysts. . Furthermore, inorganic oxide powders other than silica composite oxides cannot sufficiently achieve the above object. Although the reason for this is not clear, it is presumed that the silane coupling agent reacts more easily with the silanol groups on the surface of silica than with the hydroxyl groups on the surface of inorganic oxides other than silica. A silica composite oxide having the above acid strength means a composite oxide that contains silica as one component and cannot be physically separated from other inorganic oxides, and is generally a composite oxide that cannot be separated physically or chemically. Oxides are preferred. Further, the content of the silica component in the above composite oxide is not particularly limited as long as it has the above-mentioned acid strength, but it is generally 60 mol% or more, preferably 70 mol% or more, and more preferably 80 mol% or more. The one with the following is preferable. More specific examples of the silica composite oxide having the acid strength are as follows. For example, silica-alumina, silica-zirconia, silica-titania, silica-yttoria, silica-magnesia, silica-zinc oxide, silica-
For the purpose of adjusting the expression of surface acid sites of oxides such as lanthana, ternary composite oxide powders in which some of the acid sites are neutralized with sodium oxide, potassium oxide, etc., or silica-alumina, etc. , these oxide powders have a structure in which the surface of these oxides is thinly coated with an inorganic oxide such as silica. The specific surface area of the silica composite oxide powder in the present invention is not particularly limited, but in order to better exhibit the effects of the present invention, it is necessary to use ordinary particles with a specific surface area of 2 m ² /g or more. Silica composite oxide powder with a small diameter is most suitable. However, when the specific surface area is extremely large, the area of the interface between the organic polymer and the catalyst becomes large, making it difficult to fill a large amount of silica composite oxide powder into the organic polymer. Therefore, the specific surface area of practical silica composite oxide powder is 2 m ² /g, preferably 5 m ² /g to 50 m ² /g.
A range of g is preferred. Further, the particle size is not particularly limited, but is generally preferably from 0.03 μm to 3 μm. In the present invention, it is necessary to first treat the silica composite oxide powder with a primary or secondary aliphatic amine prior to the reaction of the silica composite oxide powder with the above properties and the silane coupling agent. . Amines other than the aliphatic amines cannot sufficiently exhibit the effects of the present invention and cannot be used. The primary or secondary aliphatic amine is not particularly limited, and known ones can be used. Specific examples of those that are generally suitable for use include:
n-propylamine, isopropylamine, n-
These include butylamine, isobutylamine, tert-butylamine, diethylamine, di-n-propylamine, and the like. The secondary amine is preferably one that does not suffer from significant steric hindrance due to carbon chains, and preferably has a straight carbon chain. The amount of these amines to be used is preferably 0.1 to 10 times, preferably 0.5 to 5 times, the amount of the silane coupling agent. The manner in which the silica composite oxide powder is treated with a primary or secondary amine is not particularly limited, and may be appropriately selected and determined as necessary. Generally, the primary amine or the secondary amine may be brought into direct contact with the silica composite oxide powder, or the two may be brought into contact in the presence of an inert organic solvent. The inert organic solvent is not particularly limited and may be selected and used as necessary, but generally methanol, ethanol,
Alcoholic solvents such as n-propanol, isopropanol, n-butanol, and isobutanol; solvents having a carbonyl group such as acetone and methyl ethyl ketone; solvents having an ether group such as ethyl ether and dioxane; methyl formate;
Solvents with ester groups such as ethyl acetate, solvents containing halogen elements such as methylene chloride, chloroform, carbon tetrachloride, pentane, n-hexane,
Aliphatic solvents such as cyclohexane and heptane,
Alternatively, an aromatic solvent such as benzene or xylene may be used. Further, the contact conditions between the silica composite oxide powder and the primary or secondary aliphatic amine are not particularly limited and may be selected from a wide range. Generally, considering the boiling point of the aliphatic amine, for example, 0
It is sufficient to select from conditions of 1 minute to 1 hour at a temperature of 50° C., reduced pressure to increased pressure, and 1 minute to 1 hour. Further, any device may be used for the contact, but generally a ball mill, an attritor, a light machine, etc. may be used. A feature of the present invention is that the silica composite oxide powder treated with a primary amine or secondary amine as described above is reacted with a silane coupling agent. Good results cannot be obtained even if the addition is carried out in the reverse order, or even if the aliphatic amine and silane coupling agent are mixed in advance and then brought into contact with the silica composite oxide powder. The reason for this is not clear, but it is probably because the rate of hydrolysis of the silane coupling agent in the presence of aliphatic amines is extremely high. This is presumed to be due to intermolecular condensation and formation of oligomers before reacting with the surface. It is generally preferable to bring the silica composite oxide powder into contact with the silane coupling agent in an inert organic solvent. The inert organic solvent may be appropriately selected from those mentioned above. Further, the same device as described above may be used for the contacting device. Further, the contact conditions are not particularly limited and may be determined as appropriate, but generally the contact conditions are at a temperature below the boiling point of the primary or secondary aliphatic amine, e.g.
50℃ or less, preferably 0 to 50℃, more preferably
You can choose from a range of 10 to 30 degrees Celsius. Also, the reaction time is
It is generally sufficient to choose from a range of 10 minutes to 1 hour. The silane coupling agent used in the present invention is not particularly limited, and any known silane coupling agent can be used. An example of a typical compound that is generally preferably used is a compound represented by the general formula Y-Si- _X3 . In the above formula, X is preferably an alkoxy group or a halogen atom. In addition, Y is generally selected from the viewpoint of use in which the silica composite oxide powder is mixed with an organic polymer and used as a composite material, and is compatible with the organic polymer or the monomer constituting the organic polymer, or Those having reactivity are preferably employed, such as NH ₂ CH ₂ CH ₂ NHCH ₂ CH ₂ CH ₂ −,
_{NH2CH2CH2CH2− , _ _}

【formula】

[Formula] HSCH ₂ CH ₂ CH ₂ −,

[Formula] etc. are suitable. Moreover, the above-mentioned X is particularly preferably an alkoxy group, and more preferably a methoxy group or an ethoxy group. In addition, one place in X is substituted with an alkyl group such as a methyl group or an ethyl group, for example

【formula】 【formula】 〔Effect of the invention〕

Composite materials in which organic polymers are filled with silica composite oxide powder surface-modified by the method of the present invention, compared to those surface-modified by conventional methods,
It is characterized by excellent long-term durability underwater. For example, the above composite material does not lose its tensile strength even when immersed in hot water for a long time. Furthermore, the bending strength and toothbrush abrasion resistance of the composite material are further improved compared to conventional ones. EXAMPLES In order to explain the present invention more specifically, Examples and Comparative Examples will be described below, but the present invention is not limited to these Examples. The strength of the surface acid sites of the inorganic oxide powder and various properties of the cured product obtained by polymerizing the paste composed of the inorganic oxide powder and organic monomer were measured by the following methods. (1) Strength of surface acid sites Kozo Tabe, Tsuneichi Takeshita, Acid-base catalyst P161-162
A method similar to that described in was used. That is, dicinnamal acetone (pKa=-3.0),
Each acid base of crystal violet (pKa=+0.8), thymol blue (pKa=1.7), methyl yellow (pKa=+3.3), bromophenol blue (pKa=+4.1), and methyl red (pKa=5.0) The indicator was dissolved in ethanol or toluene to make a 0.1 wt% solution. Next, sample powder 1.0
g, 3 ml of benzene was placed in a test tube, one drop of the above indicator solution was added thereto, and after stirring, the color development of the indicator was observed. The sample powder exhibits a basic color for an indicator with a lower pKa than an indicator with a certain acid strength (pKa ₁ ), and a more acidic color for an indicator with a higher pKa than an indicator with a lower acid strength (pKa ₂ ). The acid strength of this powder was defined as being higher than pKa ₁ and lower than pKa ₂ . (2) Tensile strength The paste was put into a stainless steel split mold with holes of 6 mm in diameter and 3 mm in depth, and pressed together with a polypropylene film. Next, apply visible light irradiator white light (manufactured by Takara Belmont) to the pressure contact surface.
The tip of the quartz rod was fixed and light was irradiated for 30 seconds. After irradiation, the cured product was removed from the split mold, and the bottom surface of the cured product was further irradiated with light for 30 seconds. Next, the cured product was immersed in distilled water at 37°C for 24 hours or boiled in water at 100°C for 72 hours, and the diametral tensile strength was measured using Toyo Baldwin Tensilon UTM-5T at a crosshead speed of 10 mm/min. It was measured. (3) Bending strength The paste was put into a stainless steel mold with holes of 2 x 2 x 20 mm, and the mold was pressed with a polypropylene film. Light irradiation was performed for 150 seconds using the same irradiator as used for the tensile strength test. Then, after immersing the cured body in distilled water at 37°C for 24 hours,
Using UTM-5T, crosshead speed 0.5
Three-point bending strength was measured at mm/min. (4) Depth of toothbrush wear The paste was put into a Teflon mold with holes measuring 10 mm long, 10 mm wide, and 1.5 mm deep, and pressed with a polypropylene film. Next, the tip of a quartz rod of a visible light irradiator Optirax was fixed to the pressure contact surface, and light was irradiated for 60 seconds. After irradiation,
The cured product was removed from the mold and immersed in distilled water at 37°C for 7 days. Load the hardened body 400g
It was worn 1500m with a toothbrush. The wear depth was determined by dividing the wear weight by the density of the hardened material. Example 1 5.0 g of 0.04% hydrochloric acid and tetraethyl silicate (Si
(OC ₂ H ₅ ) ₄ , manufactured by Nippon Colcoat Chemical Co., Ltd., product name:
Ethyl silicate 28) 176.6g methanol 0.44
The solution was hydrolyzed at 30° C. for about 1 hour while stirring. After that, tetrabutyl titanate (Ti( _onC4H9 ) ₄ , manufactured by Nippon Soda) was added to this _.
A solution of 37.7 g dissolved in 0.24 g of isobutyl alcohol was added with stirring to prepare a mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate. Next, the internal volume 3 with a stirrer
0.39 methanol and 0.78 isobutyl alcohol were introduced into a glass reaction vessel, and 0.25
An ammonia aqueous solution (concentration 25 wt%) is added to prepare an ammonia alcohol solution, and 0.8 g of tetraethyl silicate is added to this as an organosilicon compound solution for making silica seeds in methanol 18
ml of the solution was added, and 10 minutes after the completion of the addition, when the reaction solution became slightly opalescent, the above mixed solution was further added over about 5 hours to precipitate the reaction product. During the reaction, the temperature of the reaction vessel was maintained at 30°C. After the reaction was completed, stirring was continued for an additional 30 minutes, the solvent was removed from the milky white reaction liquid using an evaporator, and the mixture was further dried under reduced pressure at 80°C to obtain a milky white powder. Next, this milky white powder was fired at 900°C for 1 hour and then dispersed in an agate mortar to obtain a silica composite oxide powder containing silica and titania as constituent components.
The particle size of this silica composite oxide powder is in the range of 0.20 to 0.38 μm, as observed by scanning electron microscopy.
The average particle diameter is 0.29μm and the shape is a perfect sphere, BET
The specific surface area determined by the method was 11 m ² /g. Furthermore, the strength (pKa) of the surface acid sites was greater than 0.8 and less than 1.7. Next, 50 g of this silica composite oxide powder was transferred to a mortar, 50 ml of ethanol was added, and the mixture was stirred to form a slurry. After 0.7 ml of n-propylamine was added thereto and stirred for 5 minutes, 1.0 g of γ-methacryloxypropyltrimethoxysilane was added and stirred for 20 minutes. At this time, the evaporated amount of ethanol was replenished as needed to maintain the slurry state. Next, the solvent was removed from this slurry using an evaporator, and the slurry was dried under reduced pressure at 80°C for 15 hours to obtain a surface-modified silica composite oxide powder (hereinafter referred to as Powder I).
Next, paste (A) was prepared according to the following recipe. (A) Powder bis-GMA ^* TEGDMA ^** CQ ⁺ DMBE ⁺⁺ 70 parts by weight 18 parts by weight 12 parts by weight 0.15 parts by weight 0.15 parts by weight * 2,2-bis[4-(3-methacryloxy-2-hydroxypropoxy) ) Phenyl] Propane abbreviation** Abbreviation of triethylene glycol dimethacrylate + Abbreviation of camphorquinone++ Abbreviation of p-dimethylbenzoic acid ethyl ester The tensile strength of the cured product of this paste is 662Kg/cm ² ,
The tensile strength of the test piece after being boiled in water at 100°C for 72 hours was 636 Kg/cm ² , 96% of that before boiling, and almost no decrease in strength was observed. Bending strength is 1100
Kg/cm ² and the toothbrush wear depth was 1.6 μm. Example 2 0.04% hydrochloric acid 5.0g and tetraethyl silicate (Si
(OC ₂ H ₅ ) ₄ , manufactured by Nippon Colcoat Chemical Co., Ltd., product name:
Ethyl silicate 28) 142.0g methanol 0.44
The solution was hydrolyzed at 30° C. for about 1 hour while stirring. After that, tetrabutyl titanate (Ti( _onC4H9 ) ₄ , manufactured by Nippon Soda) was added to this _.
37.7g methanol 0.25 and isopropanol
A mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl titanate was prepared by adding a solution dissolved in a 0.39% mixed solution with stirring. Next, 0.75 methanol and 1.13 g of isobutyl alcohol were introduced into a glass reaction vessel with an internal volume of 3 and equipped with a stirrer, and 0.41 ammonia aqueous solution (concentration 25 wt%) was added thereto to prepare an ammoniacal alcohol solution. A solution of 3.0 g of tetraethyl silicate dissolved in 30 ml of methanol was added as an organosilicon compound solution for making seeds, and 10 minutes after the addition was completed, when the reaction solution became slightly milky, the above mixed solution was added. The addition took about 5 hours. Next, 108.0 g of tetraethyl silicate, 3.3 g of sodium methylate
Dissolve 0.75 g of methanol, and add this solution to approx.
It was added over time to precipitate the reaction product. During the reaction, the temperature of the reaction vessel was maintained at 20°C. After the reaction was completed, stirring was continued for another 30 minutes, the solvent was removed from the milky white reaction liquid using an evaporator, and the temperature was further heated to 80°C.
A milky white powder was obtained by drying under reduced pressure. Next, this milky white powder was fired at 900°C for 1 hour and then dispersed in an agate mortar to obtain a silica composite oxide powder containing silica, titania, and sodium oxide as constituent components. From observation using a scanning electron microscope, this silica composite oxide powder has a particle size of 0.22~
The particle size is in the range of 0.32μm, the average particle diameter is 0.23μm, and the shape is a true sphere, and the specific surface area by BET method is 14m ² /
It was hot at g. In addition, the strength of the surface acid site (pKa) is
It was greater than 1.7 and less than 3.3. Next, transfer 50g of this silica composite oxide powder to a milk bee and add ethanol.
50 ml was added and stirred to form a slurry. After 0.7 ml of n-butylamine was added thereto and stirred for 5 minutes, 1.0 g of γ-methacryloxypropyltrimethoxysilane was added and stirred for 20 minutes. At this time, the evaporated amount of ethanol was replenished as needed to maintain the slurry state. Next, the solvent was removed from this slurry using an evaporator, and the slurry was dried under reduced pressure at 80°C for 15 hours to obtain a surface-modified inorganic oxide powder (hereinafter referred to as powder). Next, a paste (B) was obtained using the following recipe. (B) Powder bis-GMA TEGDMA CQ DMBE 70 parts by weight 18 〃 12 〃 0.15 〃 0.15 〃 The tensile strength of the cured product of this paste is 638Kg/cm ² ,
The tensile strength of the cured product after boiling in water at 100°C for 72 hours was 631 Kg/cm ² , which was 99% of that before boiling, with almost no decrease in strength after boiling. In addition, the bending strength is 1150Kg/cm ² , and the toothbrush wear depth is
It was 1.4 μm. Example 3 2.7 g of 0.04% hydrochloric acid and tetraethyl silicate (Si
(OC ₂ H ₅ ) ₄ , manufactured by Nippon Colcoat Chemical Co., Ltd., product name:
Ethyl silicate 28) 120.0g isobutanol
0.4, and the solution was hydrolyzed at 30° C. with stirring for about 2 hours. Then, 36.0 g of tetrabutyl zirconate (Zr(o-nC ₄ H ₉ ) ₄ , manufactured by Nippon Soda) was added to this with stirring to prepare a mixed solution of tetraethyl silicate hydrolyzate and tetrabutyl zirconate. did. Next, 0.60 methanol was added to a glass reaction vessel with an internal volume of 3 equipped with a stirrer.
and isobutyl alcohol 0.6, and add 0.25 ammonia aqueous solution (concentration 25 wt%) to prepare an ammonia alcohol solution, and add 0.5 g of tetraethyl silicate in methanol as an organosilicon compound solution for making silica seeds. A solution dissolved in 10 ml was added, and 10 minutes after the completion of the addition, when the reaction liquid became slightly milky white, the above mixed solution was further added over about 5 hours to precipitate the reaction product. During the reaction, the temperature of the reaction vessel was maintained at 30°C. 30 more after the reaction is complete
After stirring for a minute, the solvent was removed from the milky white reaction solution using an evaporator, and the mixture was further dried under reduced pressure at 80°C to obtain a milky white powder. Next, this milky white powder was fired at 1000°C for 1 hour and then dispersed in an agate mortar to obtain a silica composite oxide powder containing silica and zirconia as constituent components. The particle size of this silica composite oxide powder was found to be in the range of 0.12 to 0.30 μm, the average particle size was 0.20 μm, and the shape was a true sphere, as observed using a scanning electron microscope.
The specific surface area determined by BET method was 16 m ² /g. In addition, the strength (pKa) of the surface acid site is greater than 0.8 and 1.7.
It was below. Next, this silica composite oxide powder
50 g was transferred to a milk drum, 50 ml of ethanol was added, and the mixture was stirred to form a slurry. After 0.7 ml of isopropylamine was added thereto and stirred for 5 minutes, 1.0 g of γ-methacryloxypropyltrimethoxysilane was added and stirred for 20 minutes. At this time, the evaporated amount of ethanol was replenished as needed to maintain the slurry state. Next, the solvent was removed from this slurry using an evaporator, and the slurry was dried under reduced pressure at 80°C for 15 hours to obtain surface-modified silica composite oxide powder (hereinafter referred to as powder). Next, a paste (C) was obtained using the following recipe. (C) Powder bis-GMA TEGDMA CQ DMBE 70 parts by weight 18 〃 12 〃 0.15 〃 0.15 〃 The tensile strength of the cured product of this paste is 711Kg/cm ²
The tensile strength of the cured product after boiling in water at 100°C for 72 hours was 706 Kg/cm ² , which was 99% of the strength before boiling, with almost no decrease in strength after boiling. The bending strength was 1080 Kg/cm ² and the toothbrush wear depth was 1.7 μm. Example 4 1.8 g of water and 104 g of distilled tetraethyl silicate (Si(OC ₂ H ₅ ) ₄ , manufactured by Nippon Colcoat Chemical Co., Ltd., product name: Ethyl silicate 28) were mixed with 100 g of methanol.
ml, and this solution was hydrolyzed at room temperature for about 2 hours with stirring.
15.0 g of sec-butoxide and 1.0 g of sodium methylate were added and stirred to prepare a mixed solution of tetraethyl silicate hydrolyzate and aluminum-sec-butoxide. A mixture of 30 ml of ammonia water (concentration 25 wt%), 30 ml of water, and 20 ml of methanol was added dropwise to this mixed solution over 1 hour, and then left at room temperature overnight to obtain a uniform gel. This gel was dried at 60°C, then baked at 900°C for 5 hours, then ground in a ball mill, and then finely ground in a jet mill (Seishin Enterprises, Model FS-4) to form silica-alumina-sodium oxide components. A silica composite oxide powder was obtained. The average particle diameter of this silica composite oxide powder was 2.1 μm according to a centrifugal sedimentation type particle size distribution analyzer (manufactured by Horiba, Ltd., CAPA-500), and the specific surface area was 2.2 m ² /g according to the BET method. . Furthermore, the strength (pKa) of the surface acid sites was greater than 0.8 and less than 1.7. Next, 10 g of this silica composite oxide powder was transferred to a mortar, and 10 ml of ethanol was added and stirred to form a slurry. Here, G-n
- After adding 0.1 ml of propylamine and stirring for 5 minutes,
γ-methacryloxypropyltrimethoxysilane
0.20g was added and stirred for 20 minutes. At this time, the evaporated amount of ethanol was replenished as needed to maintain the slurry state. Next, the solvent was removed from this slurry using an evaporator, and the slurry was dried under reduced pressure at 80°C for 15 hours to obtain surface-modified silica composite oxide powder (hereinafter referred to as powder). Next, paste (D) was prepared according to the following recipe. (D) Powder bis-GMA TEGDMA CQ DMBE 70 parts by weight 18 〃 12 〃 0.15 〃 0.15 〃 The tensile strength of the cured product of this paste is 627Kg/cm ²
The tensile strength of the cured product after boiling in water at 100°C for 72 hours was 631 Kg/cm ² , and no decrease in strength was observed after boiling. Also, the bending strength is 1650
It was Kg/ ^cm2 . Example 5 A composite range was prepared using surface-modified silica composite oxide powder in the same manner as in Example 1 except for the silane coupling agent and the amount added shown in Table 1, and the various physical properties were evaluated. It was measured. Table 1 shows the results.
It was shown to. No decrease in tensile strength was observed after boiling.

[Table] Comparative Example 1 Methanol 1.20% was introduced into a glass reaction vessel with an internal volume of 3 equipped with a stirrer, and 0.40% ammonia aqueous solution (concentration 25 wt%) was added to prepare an ammoniacal alcohol solution, and tetraethyl 30 g of silicate was added over about 1 hour to precipitate the reaction product. The temperature of the reactor was maintained at 20°C during the reaction. After the reaction was completed, stirring was continued for an additional 30 minutes, the solvent was removed from the milky white reaction liquid using an evaporator, and the mixture was further dried under reduced pressure at 80°C to obtain a milky white powder. Next, add this milky white powder to
After firing at 900°C for 1 hour, the mixture was dispersed with an agate milk drum to obtain silica powder. This silica powder has a particle size of 0.26 μm to 0.42 μm as observed using a scanning electron microscope.
The particles had an average particle diameter of 0.35 μm, were perfectly spherical, and had a specific surface area of 8 m ² /g by the BET method. The strength (pKa) of the surface acid sites was greater than 3.3 and less than 4.1. Next, this silica powder was transferred to a mortar, 10 ml of ethanol was added, and the mixture was stirred to form a slurry. After 0.14 ml of n-propylamine was added and stirred for 5 minutes, 0.20 g of γ-methacryloxypropyltrimethoxysilane was added and stirred for 20 minutes. At this time, the evaporated amount of ethanol was replenished as needed to maintain the slurry state. Next, the solvent was removed from this slurry using an evaporator, and the slurry was dried under reduced pressure at 80°C for 15 hours to obtain surface-modified silica composite oxide powder (hereinafter referred to as powder). Next, paste (E) was prepared according to the following recipe. (E) Powder bis-GMA TEGDMA CQ DMBE 70 parts by weight 18 〃 12 〃 0.15 〃 0.15 〃 The tensile strength of the cured product of this paste is 678Kg/cm ²
The tensile strength of the cured product after boiling in water at 100℃ for 72 hours is 502Kg/ ^cm2 , which is 74% of that before boiling.
It declined to . Comparative example 2 Ultrafine silica powder (amorphous SiO ₂ , specific surface area 200
m ² /g, manufactured by Tokuyama Soda Co., Ltd., product name: Reolo Seal QS-
102) 6.0 g was transferred to a milk drum, 40 ml of ethanol was added, and the mixture was stirred to form a slurry. Add 1.30 ml of n-propylamine to this, stir for 5 minutes, and then
-methacryloxypropyltrimethoxysilane
1.90g was added and stirred for 20 minutes. Next, remove the solvent from this slurry using an evaporator and heat the slurry for 15 minutes at 80℃.
By drying for hours, a surface-modified inorganic oxide powder (hereinafter referred to as powder) was obtained. The strength (pKa) of the surface acid sites before surface modification was greater than 3.3 and less than 4.1. Next, a paste (F) was prepared according to the following recipe. (F) Powder bis-GMA TEGDMA CQ DMBE 46 parts by weight 32.4 〃 21.6 〃 0.27 〃 0.27 〃 The tensile strength of the cured product of this paste is 345Kg/cm ²
After boiling the cured product in water at 100°C for 72 hours, the tensile strength was 270 Kg/cm ² , which was 78% lower than before boiling. Comparative Example 3 Quartz powder (manufactured by Tatsumori Co., Ltd., product name VXS) was finely pulverized using a jet mill (manufactured by Seishin Enterprise Co., Ltd., model FS-4) to obtain fine quartz powder (average particle size 2.7 μm,
A specific surface area of 2.0 m ² /g) was obtained. Next, this quartz powder
Transfer 10.0g to milk drumsticks, add 10ml of ethanol,
The mixture was stirred to form a slurry. After adding 0.07 ml of n-propylamine and stirring for 5 minutes, 0.10 g of γ-methacryloxypropyltrimethoxysilane was added and stirring for 20 minutes. At this time, the evaporated amount of ethanol was replenished as needed to maintain the slurry state. Next, the solvent was removed from this slurry using an evaporator, and the slurry was dried under reduced pressure at 80°C for 15 hours to obtain a surface-modified inorganic oxide powder (hereinafter referred to as powder). The strength of the surface acid sites before surface modification is
It was greater than 3.3 and less than 4.1. Next, paste (G) was prepared according to the following recipe. (G) Powder bis-GMA TEGDMA CQ DMBE 70 parts by weight 18 〃 12 〃 0.15 〃 0.15 〃 The tensile strength of the cured product of this paste is 632Kg/cm ²
After boiling the cured product in water at 100°C for 72 hours, the tensile strength was 426 Kg/cm ² , which was 67% lower than before boiling. Comparative Example 4 50 g of unsurface-treated silica composite oxide powder prepared in the same manner as in Example 1 was transferred to a milk pestle, 50 ml of ethanol was added, and the mixture was stirred to form a slurry. 1.0 g of γ-methacryloxypropyltrimethoxysilane was added thereto and stirred for 20 minutes. At this time, the evaporated amount of ethanol was replenished as needed to maintain the slurry state. Next, the solvent was removed from this slurry using an evaporator, and the slurry was dried under reduced pressure at 80°C for 15 hours to obtain a surface-modified inorganic oxide powder (hereinafter referred to as powder). Next, paste (H) was prepared according to the following recipe. (H) Powder bis-GMA TEGDMA CQ DMBE 70 parts by weight 18 〃 12 〃 0.15 〃 0.15 〃 The tensile strength of the cured product of this paste is 626Kg/cm ²
After boiling the cured product in water at 100°C for 72 hours, the tensile strength was 401 Kg/cm ² , which was 64% lower than before boiling. In addition, the bending strength is 870Kg/cm ² ,
The toothbrush wear depth was 2.5 μm. Comparative Example 5 10g of alumina powder (manufactured by Sumitomo Electric Industries, Ltd., AKP-20 average particle size 0.3μm) was transferred to a milk drumstick, and 10g of ethanol was added.
ml was added and stirred to form a slurry. here n
- After adding 0.14 ml of propylamine and stirring for 5 minutes, 0.20 g of γ-methacryloxypropyltrimethoxysilane was added and stirred for 20 minutes. At this time, the evaporated amount of ethanol was replenished as needed to maintain the slurry state. Next, the solvent was removed from this slurry using an evaporator, and the slurry was dried under reduced pressure at 80°C for 15 hours to obtain a surface-modified inorganic oxide powder (hereinafter referred to as powder). Next, paste (I) was prepared according to the following recipe. (I) Powder bis-GMA TEGDMA CQ DMBE 70 parts by weight 18 〃 12 〃 0.15 〃 0.15 〃 The tensile strength of the cured product of this paste is 581Kg/cm ²
After boiling the cured product in water at 100°C for 72 hours, the tensile strength was 424 Kg/cm ² , which was 73% lower than before boiling. In addition, the bending strength is 810Kg/cm ² ,
The toothbrush wear depth was 2.7 μm.

Claims (1)

[Claims] 1. The strength (pKa) of the surface acid site is higher than -3.0 and is 3.3.
A method for producing silica composite oxide powder, which comprises treating silica composite oxide powder in the following range with a primary or secondary aliphatic amine, and then reacting it with a silane coupling agent. 2 Silica composite oxide powder has a specific surface area of 2 to 100 m ² /
The method according to claim 1, which is within the scope of g.