JP2690364B2 - Surface treatment method of inorganic filler for dental materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a surface treatment method of an inorganic filler for dental materials (hereinafter, referred to as an inorganic filler unless otherwise specified) in detail. Specific silane having a large hydrophobic group. The present invention relates to a surface treatment method for producing an excellent surface treatment effect by reacting both in a hydrocarbon solvent when surface treating an inorganic filler using a coupling agent.

The inorganic filler treated by the method of the present invention is useful as a filler for plastics, paints, inks, coating agents, electromagnetic wave shielding materials, dental materials and the like.

(Prior Art) [gamma] -methacryloyloxypropyltrimethoxysilane (hereinafter referred to as [gamma] -MPS) is a silane coupling agent that is widely used for surface modification of inorganic fillers. Attempts have been made to further improve the surface treatment effect by substituting a longer chain alkylene group.

For example, (i) Japanese Patent Publication No. 44-20871, (ii) Sakanashi and Nishiyama, Dental Materials and Instruments, Vol. 3, No. 2, pp. 284-294 (1984),
(Iii) J. Jang et al., Proc. 41st Annual Conference, Rei
nforced Plastics / Composite Institute, The Society o
f the Plastics Industry, Session 2-C (1986), the silane coupling agent represented by the following general formula (Where n is an integer from 7 to 20) is used to describe a surface treatment method for an inorganic filler or a glass plate.

By the way, generally, as a method of uniformly reacting the silane coupling agent with the surface of the inorganic filler, for example, a method of spray-adding the coupling agent while vigorously stirring the filler, or dispersing or dissolving the inorganic filler and the coupling agent in a suitable solvent. After that, the solvent is removed, or the alkoxy group of the coupling agent is hydrolyzed by an acid catalyst in an aqueous solution to be converted into a silanol group, which is attached to the surface of the inorganic filler in the aqueous solution, and then water is removed. There is.

In any case, it is said that the reaction with the filler surface is completed by heating in the range of 50 to 150 ° C. These methods are also followed in the case of the silane coupling agent (I) of the above-mentioned known document.

For example, the surface treatment method specifically exemplified in the above-mentioned document (i) is as follows. The filler is dispersed in a solvent such as benzene, toluene or dioxane in which the silane coupling agent (I) is dissolved, and then the solvent is removed by evaporation to recover the filler to which the silane coupling agent (I) is adhered. Surface treatment is completed by heating the filler to 100 ℃ or higher. In this method, it is presumed that a substantial chemical bond occurs between the filler surface and the silane coupling agent only after the heating step after the solvent is removed.

In the literature (ii), a glass plate is immersed in an ethanol solution of 10-methacryloyloxydecyltrimethoxysilane, the glass plate is pulled up, and then heated at 110 ° C. for surface treatment.

In literature (iii), 11-methacryloyloxyundecenyltrimethoxysilane is reacted with a filler in an aqueous system in the presence of an acid catalyst.

(Problems to be Solved by the Invention) However, using the silane coupling agent (I),
When the surface treatment of the inorganic filler is performed, the surface treatment effect is insufficient when the treatment method found in the above-mentioned known literature is applied. That is, when a composite material is prepared using a filler that has been subjected to the surface treatment described in Documents (i) to (iii),
Although the filler content and mechanical strength are improved as compared with the case where the surface treatment is performed with γ-methacryloyloxypropyltrimethoxysilane which is widely used at present, the degree is not necessarily large.

An object of the present invention is to provide a treatment method which exhibits an excellent surface treatment effect when the inorganic filler is surface-treated with a silane coupling agent.

(Means for Solving the Problems) In view of the above problems, the inventors of the present invention, when performing a surface treatment using a silane coupling agent having a long-chain alkylene group, a method for exhibiting a greater surface treatment effect. I have been earnestly studying. As a result, they have found that an inorganic filler having an excellent surface treatment effect can be obtained by a method of heating and reacting a silane coupling agent and an inorganic filler in a hydrocarbon-based organic solvent, and completed the present invention.

That is, the present invention has the following general formula [Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a hydrolyzable group, R ³ is a hydrocarbon group having 1 to 6 carbon atoms, X is an oxygen or sulfur atom, m is 2 or 3, and n is Represents an integer from 8 to 20], and a silane coupling agent represented by
A method for surface treatment of an inorganic filler for dental materials, which comprises reacting in an organic solvent selected from heptane, benzene, toluene and xylene in the absence of water at a temperature range of 60 to 150 ° C. .

In the formula (II), the hydrolyzable group R ² includes a chlorine element, an alkoxy group, an isocyanate group, an acyloxy group, an iminoxy group, and the like. Among them, a chlorine atom, an alkoxy group, an isocyanate group. Is highly active and is particularly preferred.

Specific examples of the silane coupling agent (II) include the following compound groups.

There is no particular limitation on the material of the inorganic filler to be surface-treated. For example SiO ₂ , Al ₂ O ₃ , TiO ₂ , ZrO ₂ , Fe ₂ O ₃ , Ba
O, La ₂ O ₃ , oxides such as SrO ₂ , ZnO, PbO, CaO, Si
Carbides such as C, B ₄ C, WC, etc., nitrides such as Si ₃ N ₄ , BN.

In addition, minerals (eg, kaolin, clay, talc, wollastonite, mica, mica), which are the base materials of these, glass, ceramics (eg, zircon, sialon, titania, barium titanate, potassium titanate, bioglass) hydroxyapatite, etc. Is also applicable.

Furthermore, hydroxides such as Al (OH) ₃ , halides such as CaF ₂ , BaSO ₄ , CaCO ₃ , CaHPO ₄ , Ca (H ₂ PO ₄ ) ₂ , Ca
₃ (PO ₄ ) ₂ , Ca ₂ P ₂ O ₇ , Ca (PO ₃ ) ₂ , Ca ₄ P ₂ O ₇ , Mg ₂ P
Salts such as ₄ O ₁₂ , Al (PO ₃ ) ₃ and Al (PO ₄ ) are also used. Elementary metals such as Zn, Ni, Fe, Cr, Co, Pd, Pt, Ag, and Au, or alloy powders thereof are also included. The particle size of these inorganic fillers is not particularly limited, but is usually
Those in the range of 0.005 to 500 μm are preferably used.

The greatest feature of the present invention is that the reaction between the inorganic filler and the silane coupling agent (II) is carried out in a hydrocarbon solvent which may have a halogen atom. It consists in heating a suspension composed of a filler, a silane coupling agent (II) and the hydrocarbon solvent. The hydrocarbon solvent which may have a halogen atom used here has to have a boiling point of 60 ° C. or higher, preferably 70 ° C. or higher at normal pressure because it is necessary to provide a temperature at which the reaction proceeds rapidly in the heating step. Is desirable. Further, when the solvent is subsequently distilled off to recover the surface-treated filler, the boiling point at atmospheric pressure is preferably 200 ° C. or less so that the solvent can be distilled off quickly. Such solvent is selected from heptane, benzene, toluene and xylene.

Suspensions with these solvents have temperatures between 60 ° C and 150 ° C.
The range of ° C, more preferably 70 to 140 ° C is heated. If the temperature is lower than this range, the reaction takes a long time, and if the temperature is higher than this range, the (meth) acrylic group in the silica gel coupling agent is deteriorated, which is not preferable.

In the present invention, water, methanol, ethinol,
Hydroxyl groups such as acetone, tetrahydrofuran, ethyl acetate, dioxane, methyl ethyl ketone, dimethoxyethane, dimethylformamide, ether groups, ketone groups,
A solvent having an ester group or an amide group markedly inhibits the reaction between the inorganic filler and the silane coupling agent (II) and is therefore unsuitable for use.

The amount of the silane coupling agent (II) used is more than the amount capable of covering most of the surface of the inorganic filler with the monomolecular film of the silane coupling agent (II). This amount can be roughly estimated from the specific surface area value of the inorganic filler. The smaller the particle size of the inorganic filler, that is, the larger the specific surface area, the greater the amount of silane coupling agent (II) required,
Generally, 0.1 to 100 parts by weight is used with respect to 100 parts by weight of the inorganic filler. Generally, the optimum amount of silane coupling agent to be used should be determined empirically to maximize the desired physical properties of the resulting composite material.

The heating time depends on the temperature, the material of the inorganic filler, the specific surface area of the inorganic filler, the amount and type of the silane coupling agent used, the solvent, etc., and is usually about 10 minutes to 12 hours. After the heat treatment, the filler is separated and recovered from the solvent by a method such as excess, distillation under reduced pressure, centrifugation, or freeze-drying, and the surface-treated filler is obtained by sufficient drying.

(Effect) The inorganic filler surface-treated by the method of the present invention is particularly excellent in dispersibility, and it is easy to knead the filler in a large amount and uniformly in a resin or a polymerizable monomer. Further, since an inorganic filler having a highly hydrophobic surface is obtained, the polymer composite containing the filler has improved water resistance and is suitable as a dental material. Besides dental materials, it is also useful as a filler for general molding resins, coating agents, paints, inks, adhesives, and electromagnetic wave shielding materials.

(Examples) Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Quartz powder was pulverized with a vibrating ball mill to obtain an average particle size of 2.5 μm.
A powder with a particle size range of 0.1 to 20 μm was obtained. 300 g of this powder, 500 ml of toluene, and 6 g of 11-methacryloyloxyundecyltrimethoxysilane were mixed in a separable flask equipped with a thermometer, a mechanical stirrer, and a reflux condenser, and the suspension was vigorously stirred in an oil bath. At 120 ℃
The mixture was heated to (bath temperature) and refluxed for 2 hours. During this time, the temperature inside the flask was 111 ° C. After cooling, toluene was distilled off under reduced pressure to recover quartz powder, which was dried under vacuum for 12 hours to obtain a surface-treated filler.

The following consistency measurement was performed for the purpose of evaluating the dispersibility of the obtained filler in a hydrophobic medium.

Measurement of Consistency 200 parts by weight of the surface-treated filler and 100 parts by weight of fluid paraffin were kneaded to obtain a paste-like mixture. Weigh 0.5 ml of the paste and put it on a glass plate (5
It was left to stand up so that it would be raised in the center of (× 5 cm). Next, place a glass plate (5 x 5 cm) with a load of 40 g on it gently and measure the major axis and minor axis of the spread paste after 120 seconds through the glass plate, and calculate the arithmetic mean of both. The value was taken as the consistency. The values are shown in Table 1, which is the average of three independent measurements. The measurement is 25 ℃
It was carried out in a constant temperature room.

The better the dispersibility of the filler, the lower the viscosity of the paste and the higher the value of consistency defined above. Therefore,
The larger the value of the consistency, the better the dispersibility of the filler.

Examples 2 to 5 and Comparative Examples 1 to 4 Surface treatment according to the method of Example 1 was performed using the quartz powder of Example 1 under the solvent and reaction temperature conditions shown in Table 1. The results of the consistency measurement of the obtained filler are also shown in Table 1.

Comparative Example 5 450 ml of water (pH 3.5) containing 0.5% acetic acid, polyoxyethylene monolauryl ether (average of ethoxy groups in one molecule)
(15 pieces) 50 g were suspended, and 6 g of 11-methacryloyloxyundecyltrimethoxysilane was added thereto and stirred for 3 hours at room temperature. Then, 300 g of the same quartz powder as in Example 1 was added, and the mixture was further stirred for 2 hours. The suspension was centrifuged, the supernatant was removed, and the powder was collected. After vacuum drying, it was dried at 110 ° C. for 2 hours to obtain a surface-treated filler. The consistency was measured according to the method of Example 1, and the results are shown in Table 2.

Comparative Example 6 1 kg of the quartz powder of Example 1 was sprayed with a mixture of 20 g of 11-methacryloyloxyundecyltrimethoxysilane and 200 mg of triethylamine while stirring well with a mixer. Subsequently, the mixture was well stirred and then dried by heating at 110 ° C. for 2 hours to obtain a surface-treated filler. The consistency was measured according to the method of Example 1, and the results are shown in Table 2.

Comparative Example 7 The filler obtained in Comparative Example 1 was further heat-treated at 110 ° C. for 2 hours. The consistency of this filler was measured according to the method of Example 1, and the results are shown in Table 2.

Example 7 In Example 1, instead of distilling toluene under reduced pressure when recovering the quartz powder, liquid was removed by suction, the quartz powder was thoroughly washed with toluene, and then vacuum dried. The Fourier transform infrared absorption spectrum of the obtained filler was measured by the diffuse reflection method, and the difference spectrum between the silica powder after the surface treatment and the silica powder before the surface treatment was obtained.
The peak derived from the carbonyl group at cm ^-1 , 2920 cm ^-1 and
A peak derived from C—H bond was observed at 2850 cm ^−1, and it was found that the silane coupling agent was bonded on the surface of the quartz powder.

Examples 8 to 13 and Comparative Example 8 Instead of the 11-methacryloyloxyundecyltrimethoxysilane used in Example 1, a silane coupling agent shown in Table 3 was used to perform surface treatment in the same manner as in Example 1. went. The consistency of the obtained filler was measured, and the results are shown in Table 3.

Example 14 1,10-decanediol dimethacrylate 25 parts by weight 2,2,
Addition product of 1 mol of 6-trimethylhexamethylene diisocyanate and 2 mol of glycerin dimethacrylate (U-
40 parts by weight, 2,2-bis (methacryloyloxypolyethoxyphenyl) propane (there is an average of 2.6 ethoxy groups in one molecule and is called D-2.6E) 35
Part by weight and 0.5 part by weight of 2,4,6-trimethylbenzoyldiphenylphosphine oxide were mixed and dissolved to obtain a polymerizable monomer composition. 100 parts by weight of this monomer composition and 400 parts by weight of the surface-treated filler obtained in Example 1 were kneaded and then degassed in vacuum to obtain a polymerizable composition. This composition was irradiated with a xenon lamp (1300W) for 90 seconds to cure, and then 1
When the compression strength and bending strength of the cured product obtained by heating at 20 ° C. for 30 minutes were measured, the average values of 8 samples were 4960 kg / cm ² and 1960 kg / cm ² , respectively.

Comparative Example 9 400 parts by weight of the surface-treated filler obtained in Comparative Example 8 was kneaded with 100 parts by weight of the monomer composition of Example 14 to obtain a polymerizable composition. Curing the composition under the conditions of Example 14,
The compressive strength and bending strength were measured and found to be 46
Was 50kg / cm ² and 1760kg / cm ^2.

Claims (1)

(57) [Claims] 1. The following general formula: [Wherein R ¹ is a hydrogen atom or a methyl group, R ² is a hydrolyzable group, R ³ is a hydrocarbon group having 1 to 6 carbon atoms, X is an oxygen or sulfur atom, m is 2 or 3, and n is Represents an integer from 8 to 20], and a silane coupling agent represented by
A method for treating the surface of an inorganic filler for dental materials, which comprises reacting in an organic solvent selected from heptane, benzene, toluene and xylene in the temperature range of 60 to 150 ° C in the substantial absence of water.