JP6301639B2 - Silica composite fine particles and method for producing curable composition for dental material - Google Patents

Description

The present invention relates to a method for producing silica composite fine particles effective for modifying dental materials that require hardness, grindability, transparency, and the like, and a method for producing a curable composition for dental materials using the same.

  A meta (acrylate) resin having excellent transparency and molding processability has been used as a material for artificial teeth and denture bases, but dimensional stability, hardness and grindability due to curing shrinkage have not been sufficient. Therefore, a composition in which inorganic particles such as silica are dispersed in a meth (acrylate) monomer has been used. However, inorganic particles such as silica are difficult to disperse in a meth (acrylate) monomer. There was a problem that transparency was lowered.

Patent Documents 1 to 3 disclose compositions in which a colloidal silica treated with a silane compound is dispersed in a meta (acrylate) monomer and then the solvent is distilled off. However, since pretreatment to colloidal silica and evaporation of the solvent contained in colloidal silica are necessary, the manufacturing process is complicated, which is industrially disadvantageous.
Japanese Patent Laid-Open No. 5-209027 JP 7-17820 A Japanese Unexamined Patent Publication No. 7-291817

An object of the present invention is to provide a method for producing silica composite fine particles having excellent productivity effective for modifying dental materials that require hardness, grindability, transparency, and the like, and a curable composition for dental materials using the same. It is to provide a manufacturing method .

The present invention is a method for producing silica composite particles , wherein a silica dispersed monomer in which silica particles are dispersed in a monomer to which isopropyl alcohol is added is polymerized. Moreover, it is a manufacturing method of the curable composition for dental materials characterized by containing this silica composite particle.

  The silica composite particles of the present invention are composited with the resin in a dispersed state by performing polymerization after dispersing the silica particles in the monomer. For this reason, when used for modifying dental materials, it is excellent not only in hardness and grindability but also in transparency. Moreover, since the silica composite particle of this invention and the curable composition for dental materials are obtained by a simple process, it is industrially excellent.

  The silica composite particles of the present invention can be obtained by adjusting the silica dispersion monomer by dispersing the silica particles in a monomer to which an alcohol is added, and polymerizing the silica dispersion monomer. The silica particles used in the present invention are not particularly limited, but it is preferable to use silica powder having a particle size of 10 to 40 nm that has been subjected to a hydrophobization treatment in terms of dispersibility in monomers. By dispersing the silica particles in the monomer, the hardness and grindability of the silica composite particles and the curable composition for dental materials using the same can be improved.

  The monomer is preferably composed mainly of methyl methacrylate from the viewpoint of the hardness and transparency of the particles obtained. In addition, ethyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, isobornyl (meth) acrylate, hexachlorobutyl (meth) acrylate, etc. A monomer may be used in combination.

  Moreover, the grindability of a silica composite particle and a curable composition for dental materials using the same can be improved by using a crosslinking component. Examples of crosslinking components include aromatic divinyl monomers such as divinylbenzene; ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di ( Alkylene glycol di (meth) acrylate such as meth) acrylate; polyalkylene glycol di (meth) acrylate such as diethylene glycol di (meth) acrylate and triethylene glycol di (meth) acrylate; trimethylolpropane di (meth) acrylate, pentaerythritol Polyol poly (meth) acrylate such as tetra (meth) acrylate; allyl (meth) acrylate, allyl malate, diallyl fumarate, diallyl itaconate, triallyl ester Allyl compounds such as cyanurate can be exemplified. When the crosslinking component is excessive, the impact resistance when it is made into a dental material is lowered. Therefore, it is preferably used in an amount of 5% by weight or less, preferably 2% by weight or less based on the monomer.

Even if the silica particles and the monomer are simply mixed, the dispersibility is poor, so it is necessary to add alcohol. As the alcohol, a lower alcohol having an appropriate amphiphilic property is preferable. However, isopropyl alcohol is used because a low molecular weight alcohol such as methanol and ethanol has a low boiling point and is difficult to handle from the viewpoint of safety. As for the amount added, about 2 to 3% by weight is sufficient when the monomer is mainly composed of methyl methacrylate.

When adjusting the silica-dispersed monomer, in order to improve the dispersibility of the silica particles in the monomer, the silica-dispersed monomer by gradually adding the silica particles into the monomer to which alcohol has been added under stirring It is preferable to obtain a body. When polymerizing silica dispersion monomer, hydroxypropyl cellulose, gelatin, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyethylene glycol, polyoxyethylene-polyoxypropylene block copolymer, polyacrylamide, polyacrylic acid, polyacrylic acid Add water-soluble polymer such as salt, sodium alginate, polyvinyl alcohol, inorganic substances such as tricalcium phosphate, titanium oxide, calcium carbonate as a dispersant, and stir and disperse with a homomixer to form droplets. A monomer dispersion is preferably used. In this case, anionic surfactants such as sodium dodecylbenzene sulfonate and sodium lauryl sulfate, nonionic surfactants, and inhibitors of aqueous phase polymerization such as sodium nitrite are added to stabilize the dispersion of the monomer. May be.
Moreover, the particle diameter of the silica composite particle obtained after superposition | polymerization is controllable by adjusting a droplet diameter. Specifically, methods for reducing the droplet diameter include methods such as increasing the amount of dispersant added, strengthening the stirring, and increasing the stirring time. The particle diameter of the silica composite particles is preferably 15 to 120 μm, and if it is outside this range, transparency may not be obtained when a molded product is formed.

  When polymerizing the silica dispersion monomer, a radical polymerization initiator is used. Specific examples include organic peroxides such as benzoyl peroxide, o-methoxybenzoyl peroxide, o-chlorobenzoyl peroxide, lauroyl peroxide, cumene hydroperoxide; 2,2′-azobisisobutyronitrile, 2 And azo compounds such as 2'-azobis (2,4-dimethylvaleronitrile). Moreover, when using an oil-soluble polymerization initiator, you may disperse | distribute to a monomer previously. The amount used is 0.01 to 5% by weight, preferably about 0.1 to 2% by weight, based on the total amount of monomers.

  After polymerizing the silica-dispersed monomer, for example, by further polymerizing a monomer consisting only of methyl methacrylate, a core-shell type silica composite particle comprising a core layer containing silica and a shell layer consisting only of a resin It can also be. By adopting a core-shell type, the impact resistance of the molded product can be improved.

  The silica composite particles of the present invention are suitable for a curable composition for dental materials that is used as a material for artificial teeth and denture bases. The curable composition for a dental material is obtained as a bowl-shaped composition by mixing silica composite particles, a monomer mainly composed of methyl methacrylate, and a radical polymerization initiator. Although the curable composition for dental materials can be cured by heating, the method of immersing in boiling water is widely adopted because it is simple and safe. As the radical polymerization initiator, the same radical polymerization initiator as used when polymerizing the silica-dispersed monomer can be used. Considering dispersibility in methyl methacrylate, use of boiling water (100 ° C.), and the like, it is preferable to use, for example, benzoyl peroxide. Moreover, it is preferable that the ratio of the silica particle to the curable composition for dental materials will be 5 to 30 weight%. When silica composite particles having a high content of silica particles are used, the proportion of silica particles in the curable composition for dental materials can be adjusted by using polymethyl methacrylate particles in addition to the silica composite particles.

  When the curable composition for dental materials of the present invention is cured and ground with a drill or the like to obtain a material for artificial teeth or denture bases, it has excellent grindability (hard feel and shavings scatter in powder) Easy to process. Moreover, it is excellent in transparency and hardness.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and demonstrated in detail about this invention, a specific example is shown and it does not specifically limit to these.

Preparation of Silica Dispersing Monomer (A) 300 parts by weight of methyl methacrylate, 6 parts by weight of isopropyl alcohol and 2.4 parts by weight of dilauroyl peroxide as a polymerization initiator are weighed in a glass container with a capacity of 1 L. The mixture was stirred and dissolved to obtain a monomer mixture. To this monomer mixture, 100 parts by weight of hydrophobic silica particles (primary particle size 12 nm) are gradually added under stirring to form a jelly, and further stirred for 2 minutes to obtain a silica mixed monomer solution having fluidity. It was. The silica mixed monomer liquid was dispersed using a disperser to obtain a silica dispersed monomer (A).

Preparation of Monomer Dispersion (A-1) 650 parts by weight of ion-exchanged water and Prisurf A-210G (surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name) 0.07 weight in a 2 L separable flask Part, TCP-10U (calcium phosphate, manufactured by Taihei Chemical Industrial Co., Ltd., trade name) was weighed to obtain a dispersant solution. Silica dispersion monomer (A) was added to this dispersant liquid and dispersed using a disperser to obtain a monomer dispersion liquid (A-1). When the droplet diameter of this monomer dispersion was observed with an optical microscope, it was approximately 50 μm.

Example 1
The monomer dispersion (A-1) was charged into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, heated to 75 ° C. while stirring under a nitrogen stream, and after confirming heat generation, 80 The silica composite particles of Example 1 were obtained by polymerization at ˜85 ° C. for 3 hours. The volume average particle diameter of these particles was 48.9 μm.

Comparative Example 1
The silica composite particles of Comparative Example 1 were obtained in the same manner as in Example 1 except that isopropyl alcohol was not used when preparing the silica dispersion monomer. The volume average particle diameter of these particles was 55.7 μm.

Preparation of Silica Dispersing Monomer (B) 300 parts by weight of methyl methacrylate, 2.1 parts by weight of ethylene glycol dimethacrylate (trade name: Light Ester EG), 6 parts by weight of isopropyl alcohol in a 1 L glass container Then, 2.4 parts by weight of dilauroyl peroxide was weighed and dissolved by stirring with a magnetic stirrer to obtain a monomer mixture. Under stirring, 100 parts by weight of hydrophobic silica particles (primary particle size 12 nm) were gradually added to the monomer mixture, and the mixture was blended with the whole system to obtain a silica mixed monomer solution. The silica mixed monomer liquid was dispersed using a disperser to obtain a silica dispersed monomer (B).

Preparation of monomer dispersion (B-1) In a 2 L separable flask, weigh 750 parts by weight of ion-exchanged water, 0.2 parts by weight of Prisurf A-210G, and 200 parts by weight of TCP-10U. A drug solution was obtained. Silica dispersion monomer (B) was added to this dispersant liquid and dispersed using a disperser to obtain a monomer dispersion liquid (B-1). When the droplet diameter of this monomer dispersion was observed with an optical microscope, it was approximately 40 μm.

Example 2
A monomer dispersion of B-1 was charged into a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer, heated to 75 ° C. with stirring under a nitrogen stream, and 80 to 80 after confirming the exotherm. Polymerization was carried out at 85 ° C. for 1 hour and 30 minutes. After the polymer was cooled to 50 ° C. or lower, a monomer solution in which 0.04 parts by weight of dilauroyl peroxide was dissolved in 40 parts by weight of MMA monomer was continuously dropped into the system over 30 minutes. After completion of dropping under the monomer droplets, the temperature was raised to 80 ° C. and polymerized at 80 to 85 ° C. for 2 hours to obtain silica composite particles of Example 2. The volume average particle diameter of these particles was 40.8 μm.

Preparation of Silica Dispersing Monomer (C) 300 parts by weight of methyl methacrylate, 5 parts by weight of triethylene glycol dimethacrylate (trade name Light Ester 3EG, manufactured by Kyoeisha Chemical Co., Ltd.), 6 parts by weight of isopropyl alcohol, 2.3 parts by weight of lauroyl peroxide was weighed and dissolved by stirring with a magnetic stirrer to obtain a monomer mixture. While stirring, 85 parts by weight of hydrophobic silica particles (primary particle size: 12 nm) were gradually added to this monomer mixed solution and blended with the whole system to obtain a silica mixed monomer solution. The silica mixed monomer liquid was dispersed using a disperser to obtain a silica dispersed monomer (C).

Preparation of Monomer Dispersion (C-1) In a 2 L separable flask, weigh 580 parts by weight of ion-exchanged water, 0.7 parts by weight of PRISURF A-210G, and 720 parts by weight of TCP-10U. A drug solution was obtained. Silica dispersion monomer (C) was added to this dispersant liquid, and dispersion treatment was performed using a disperser to obtain a monomer dispersion liquid (C-1). When the droplet diameter of this monomer dispersion was observed with an optical microscope, it was about 20 μm.

Example 3
The monomer dispersion (C-1) was charged into a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, heated to 75 ° C. while stirring under a nitrogen stream, and after confirming heat generation, 80 The silica composite particles of Example 3 were obtained by polymerization at ˜85 ° C. for 3 hours. The volume average particle diameter of these particles was 19.3 μm.

Test Evaluation Method Weigh 50 parts by weight of the silica composite particles of each example and comparative example, 0.15 parts by weight of benzoyl peroxide, and 25 parts by weight of methyl methacrylate monomer in a polyethylene bag with a chuck, seal the bag, and mix. A bowl-shaped kneading liquid was obtained. The kneaded liquid in a bowl shape was put into a mold and pressed at a pressure of 8 MPa using a press. After pressing, the mold was immersed in boiling water for 20 minutes to thermally polymerize the kneaded liquid to obtain a molded product.
Moreover, it replaced with 50 weight part of silica composite particles, and performed similarly except having used 50 weight part of polymethyl methacrylate particle | grains, and obtained the molding of the comparative example 2. FIG. Furthermore, it was carried out in the same manner except that 38.5 parts by weight of polymethyl methacrylate particles and 11.5 parts by weight of hydrophobic silica particles used in the preparation of the silica dispersion monomer were used instead of 50 parts by weight of silica composite particles, A molded product of Comparative Example 3 was obtained.

The following performance evaluation was implemented about the obtained molding.
Transparency: Transparency was evaluated in the following three stages.
◎ Transparent, ○ Almost transparent, × Cloudiness hardness: Vickers hardness of the molded product was measured using a Vickers hardness meter.
Grinding feeling: The molded product was ground using a diamond grinding material for dental technicians, and the feeling during grinding and the state of scraped residue were confirmed. The comparative sensory evaluation value was described with Comparative Example 3 as 100.

The curable composition for dental materials using the silica composite fine particles of each Example was excellent in all of hardness, grindability, and transparency. On the other hand, Comparative Example 1 in which no alcohol was added during the dispersion of the silica particles had poor hardness and sharpness. In Comparative Example 2 containing no silica particles, although excellent in transparency, the shaving feeling was poor, and in Comparative Example 3 in which polymethyl methacrylate particles and silica particles were used in combination without being compounded, the transparency was poor.

Claims (6)

A method for producing silica composite particles , wherein a silica-dispersed monomer in which silica particles having a particle diameter of 10 to 40 nm are dispersed in a monomer to which isopropyl alcohol is added is polymerized. The silica dispersion monomer is obtained by dispersing silica particles having a particle diameter of 10 to 40 nm in a monomer to which isopropyl alcohol is added, and polymerizing the droplets. A method for producing silica composite particles . The method for producing silica composite particles according to claim 1, wherein the monomer contains a crosslinking component and has a non-crosslinked shell layer. The method for producing silica composite particles according to any one of claims 1 to 3, wherein the average particle size is 15 to 120 µm. The process according to claim 1 to 4 containing silica composite particles according to the production method according to any one (except for the urethane (meth) acrylate), dental materials curable composition which comprises causing thermal polymerization. The method for producing a curable composition for a dental material according to claim 5, wherein the proportion of the silica composite particles in the curable composition for a dental material is 5 to 30% by weight .