JP2019178105A - Production method of resin material for dental cutting processing - Google Patents

Abstract

An object of the present invention is to provide a method for easily producing a resin material for dental cutting in which a decrease in strength after immersion in water is suppressed. In a method for producing a resin material for dental cutting, which is a cured product of a curable composition comprising (A) a polymerizable monomer, (B) a polymerization catalyst, and (C) inorganic particles, A method for producing a resin material for dental cutting, wherein a heat treatment is performed at a temperature between -50 ° C and + 100 ° C of a body loss tangent peak temperature for 1 hour to 200 hours. [Selection diagram] None

Description

  The present invention relates to a method for producing a resin material for dental cutting for producing a dental prosthesis by cutting.

  A curable composition that is a raw material for a resin material for dental cutting is generally composed of a polymerizable monomer, a filler, and a polymerization initiator as main components. Composite resin, hard resin, artificial tooth, cement It is applied as a cutting resin material. What hardened | cured the curable composition industrially is called the resin material for dental cutting, and is widely used for the processing application in CAD / CAM with the advance of digitization in recent dentistry. On the other hand, resin materials for dental cutting work are still not enough in terms of mechanical strength to function in harsh oral environments, especially long-term moist environments, compared to other materials such as metals and ceramics. Improvement is still needed from the viewpoint of compatibility with other physical properties such as aesthetics and operability. In particular, it is very important to ensure the desired physical properties after strength reduction due to wetting.

  From the above background, it can be said that the bending strength after immersion in water, which is closer to the oral environment, reproduces the strength at the time of actual use, and it is essential to improve the strength. However, until now, studies on improvement of initial physical properties have been actively conducted, but studies on bending strength after water absorption simulating the oral cavity have hardly been studied.

In general, in order to improve the strength of the curable composition, a method of increasing the inorganic filling rate, a method of improving the composition such as using an irregularly shaped filler such as a pulverized filler as the inorganic filler, or 1 MPa in the polymerization step A method of performing the above-described high-pressure treatment, a method of pressing with a press machine in a heated state, and the like have been devised. (Patent Documents 1 to 3)
When the filling rate is improved to improve the strength, or when the filler has an irregular shape, the paste properties are greatly affected, and problems such as a decrease in handling properties in the manufacturing process become significant, which is not preferable. . Furthermore, since high-pressure processing requires a dedicated device, such processing is not easy to implement. In addition, there is no indication as to how much the strength will decrease after soaking a material created by a different manufacturing method as described above in water, and how it can be suppressed. It was a situation where I had no idea about the method.

  Non-Patent Document 1 describes that a dental CAD / CAM composite resin block exhibits bending strength equivalent to that of a ceramic material. On the other hand, the three-point bending strength after 7 days of immersion in water is less affected by immersion in ceramic materials, whereas existing dental CAD / CAM composite resin blocks are about 80% of the initial. It has been shown to decrease to strength.

JP-A-10-323353 JP2015-97854 JP2016-13997

Dental Maritals Journal 2014, 33 (5): 705-710

  The problem to be solved by the present invention is to provide a method for easily producing a resin material for dental cutting, in which strength reduction after immersion in water is suppressed.

  The present inventors have intensively studied to solve the above problems. As a result, it has been found that by performing heat treatment at a specific temperature, a decrease in strength after immersion in the obtained dental cutting resin material is suppressed, and the present invention has been completed.

  That is, the present invention relates to a resin material for dental cutting which is a cured product of a curable composition comprising (A) a polymerizable monomer, (B) a polymerization catalyst, and (C) inorganic particles. A method for producing a resin material for dental cutting, wherein heat treatment is performed at a loss tangent peak temperature between −50 ° C. and + 100 ° C. for 1 hour to 200 hours.

  In the production method of the present invention, the heat treatment is preferably performed at a temperature between −30 ° C. and + 50 ° C. of the loss tangent peak temperature of the cured body.

  In the production method of the present invention, the heat treatment is preferably performed at a temperature higher than the polymerization temperature of the curable composition.

  In the production method of the present invention, it is preferable that the heat treatment is performed at atmospheric pressure to 0.9 MPa under an inert gas.

  In the production method of the present invention, the cooling rate after the heat treatment is preferably 20 ° C./min or less.

  Since the resin material for dental cutting obtained by the production method of the present invention is heat-treated at a specific temperature, there is little decrease in strength after immersion in water. Moreover, according to the manufacturing method of this invention, the resin material for dental cutting with high intensity | strength can be manufactured more simply.

  Although it is not clear why the manufacturing method of the present invention suppresses the decrease in strength of the dental cutting resin material after immersion in water, the strain remaining at the interface between the resin and filler contained in the dental cutting resin material is reduced. It is presumed that the fragile sites that cause water absorption deterioration are reduced. In addition, there is little change in color tone due to discoloration or discoloration due to heat treatment.

  The method for producing a resin material for dental cutting according to the present invention is obtained by polymerizing a curable composition comprising (A) a polymerizable monomer, (B) a polymerization catalyst, and (C) inorganic particles, which will be described later. A specific heat treatment is performed on the body.

  A curable composition for obtaining a cured product to be subjected to heat treatment comprises (A) a polymerizable monomer, (B) a polymerization catalyst, and (C) inorganic particles.

<(A) Polymerizable monomer>
As the polymerizable monomer (A) used in the curable composition of the present invention, a known polymerizable monomer can be used. Examples of the polymerizable monomer include a radical polymerizable monomer and a cationic polymerizable monomer. In general, a radical polymerizable monomer is preferably used. As a radically polymerizable monomer, as a polymerizable functional group that is a functional group having a property of polymerizing, (meth) acrylic acid ester group, (meth) acrylamide group, vinyl ester group, vinyl ether group, styryl group, epoxy group, A radical polymerizable monomer having an oxetane group and the like can be mentioned. When a plurality of polymerizable functional groups are contained in one molecule, each polymerizable functional group may be the same or different within one molecule. A particularly preferred polymerizable monomer is a (meth) acrylate-based polymerizable monomer or (meth) acrylamide group having a (meth) acrylate group as a polymerizable functional group from the viewpoint of biosafety. The (meth) acrylamide derivative is a (meth) acrylic acid ester polymerizable monomer from the viewpoint of good polymerizability. In the present invention, the expression “(meth) acryl” is used to include both methacryl and acryl.

<(B) Polymerization catalyst>
The (B) polymerization catalyst used for the curable composition in the present invention is for polymerizing and curing the (A) polymerizable monomer. Polymerization methods include reaction by light energy such as ultraviolet light and visible light (hereinafter referred to as photopolymerization), chemical reaction between peroxide and accelerator, and heat energy (hereinafter referred to as thermal polymerization). Any method may be used. Photopolymerization catalysts and thermal polymerization catalysts are preferred because the timing of polymerization can be arbitrarily selected by energy applied from the outside, such as light and heat, and the operation is simple. Also, when used as a resin material for dental cutting, it is necessary to obtain a hardened body having a large thickness and toning, so it may be difficult to transmit light to the inside of the curable composition, Thermal polymerization catalysts are more preferred. Various polymerization catalysts shown below may be appropriately selected and used according to the polymerization method employed.

  For example, as a photopolymerization initiator, benzoin alkyl ethers such as benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether, benzyl ketals such as benzyl dimethyl ketal and benzyl diethyl ketal, benzophenone, 4,4′-dimethylbenzophenone, Benzophenones such as 4-methacryloxybenzophenone, diacetyl, 2,3-pentadione benzyl, camphorquinone, α-diketones such as 9,10-phenanthraquinone, 9,10-anthraquinone, 2,4-diethoxy Thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, methylthioxanthone, bis- (2,6-dichlorobenzoyl) phenylphosphine oxide, bis- (2,6-dichloroben) Yl) -2,5-dimethylphenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -4-propylphenylphosphine oxide, bis- (2,6-dichlorobenzoyl) -1-naphthylphosphine oxide, 2,4 Acylphosphine oxides such as 1,6-trimethylbenzoyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide can be used.

  Incidentally, a reducing agent is often added to the photopolymerization initiator. Examples thereof include tertiary amines such as 2- (dimethylamino) ethyl methacrylate, ethyl 4-dimethylaminobenzoate, and N-methyldiethanolamine. , Aldehydes such as lauryl aldehyde, dimethylaminobenzaldehyde, terephthalaldehyde, and sulfur-containing compounds such as 2-mercaptobenzoxazole, 1-decanethiol, thiosalicylic acid, and thiobenzoic acid.

  Examples of the thermal polymerization initiator include benzoyl peroxide, p-chlorobenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxydicarbonate, and diisopropyl peroxydicarbonate. Peroxides, azo compounds such as azobisisobutyronitrile, tributylborane, tributylborane partial oxide, sodium tetraphenylborate, sodium tetrakis (p-fluorophenyl) borate, triethanolamine tetraphenylborate And boron compounds such as 5-butyl barbituric acid, 1-benzyl-5-phenyl barbituric acid and the like, and sulfinates such as sodium benzenesulfinate and sodium p-toluenesulfinate. . It is preferable to use a peroxide such as benzoyl peroxide because a cured product having a high strength can be obtained.

  These polymerization initiators may be used alone or in combination of two or more. It is preferable that the compounding quantity of a polymerization initiator is 0.01-5 mass parts with respect to 100 mass parts of (A) polymeric monomers.

<(C) Inorganic particles>
The inorganic particles (C) used in the curable composition in the present invention increase the strength of the resin material for dental cutting, increase the elastic modulus to reduce bending, increase wear resistance, and suppress polymerization shrinkage. It is a filler added for the (C) In addition to the inorganic particles, the filler may include organic particles and organic-inorganic composite particles.

  (C) Since the amount of inorganic particles affects the strength of the resin material for dental cutting and the properties of the curable composition paste, the portion in the oral cavity where the resin material for dental cutting is used (molar teeth, anterior teeth, etc.) Although it may be selected according to the required performance (ease of flow, etc.), it is generally used in a proportion of 100 to 2000 parts by mass with respect to 100 parts by mass of the polymerizable monomer (A). Since the resin material for dental cutting is generally highly polymerized and has poor adhesiveness, it is preferable that the amount of inorganic particles is high so that the silane coupling agent can easily act. More preferably, it is 400-700 mass parts, Most preferably, it is used in the ratio of 500-600 mass parts.

  There is no restriction | limiting in (C) inorganic particle used for the curable composition in this invention, All can be used if it is an inorganic particle currently used as a filler by the well-known curable composition. Specifically, a simple substance of a metal selected from Group I, II, III, IV, transition metal of periodic table; oxide or composite oxide of these metals; glass containing these metals; fluoride, carbonate, Metal salts composed of sulfates, silicates, hydroxides, chlorides, sulfites, phosphates, etc .; and composites of these metal salts. Suitable metal oxides such as amorphous silica, quartz, alumina, titania, zirconia, barium oxide, yttrium oxide, lanthanum oxide, ytterbium oxide; silica-zirconia, silica-titania, silica-titania-barium oxide, silica -Silica-based composite oxides such as titania-zirconia; glass such as borosilicate glass, aluminosilicate glass, fluoroaluminosilicate glass; metal such as barium fluoride, strontium fluoride, yttrium fluoride, lanthanum fluoride, ytterbium fluoride Fluorides; inorganic carbonates such as calcium carbonate, magnesium carbonate, strontium carbonate and barium carbonate; metal sulfates such as magnesium sulfate and barium sulfate are employed. (C) The inorganic particles may be a mixture of these different materials.

  Of these, the metal oxide and the silica-based composite oxide are preferably fired at a high temperature in order to obtain a dense material and to suppress a decrease in strength after immersion in water. Moreover, in order to improve the effect, it is preferable to contain a small amount of Group I metal oxide such as sodium.

  Among the inorganic particles of the above materials, the silica-based composite oxide particles can be easily adjusted in refractive index. Furthermore, since it has a large amount of silanol groups on the particle surface, it is particularly preferable because surface modification can be easily performed using a silane coupling agent or the like.

  The above exemplified particles of silica-zirconia, silica-titania, silica-titania-barium oxide, silica-titania-zirconia, etc. are suitable because they have high X-ray contrast properties. Furthermore, since a cured product having more excellent wear resistance can be obtained, silica-titania particles and silica-zirconia particles are most preferable.

  (C) A well-known thing can be used without a restriction | limiting as a shape of an inorganic particle. Various shapes such as a spherical shape, a substantially spherical shape, an indefinite shape, a hemispherical shape, a lens shape, a concave shape, a mushroom shape, an aggregated shape, a cluster shape, a dimple shape, a plate shape, and a fiber shape can be used. In view of the high strength of the cured product of the curable composition of the present invention, (C) those containing an irregular shape as inorganic particles are preferred, and a combination of an irregular shape and a spherical shape is more preferred. A desirable ratio of the irregularly shaped particles and the spherical particles is 50 to 250 parts by mass, more preferably 100 to 150 parts by mass with respect to 100 parts by mass of the spherical particles.

  (C) The particle diameter and particle size distribution of the inorganic particles are not particularly limited. A suitable particle diameter of the inorganic particles is in the range of 0.001 to 50 μm. Since the particle size distribution can increase the inorganic particle packing rate by fine packing, (C-1) inorganic particles having an average particle diameter of 1 to 50 μm (hereinafter also referred to as micron-order inorganic particles), (C-2) Inorganic particles having an average particle size of 0.1 to less than 1 μm (hereinafter also referred to as submicron-order inorganic particles), and (C-3) Inorganic particles having an average particle size of less than 0.001 to 0.1 μm (hereinafter referred to as nano-order) (Also referred to as inorganic particles). In addition, it is possible to increase the filling rate by using a bimodal particle size distribution having a frequency peak in each particle size order, rather than a single-peak particle size distribution with a single frequency peak. To preferred. Further, it is preferable that the number of coarse particles is small because the strength is high and the polishing property is good. The particle size of the cumulative particle size distribution of 90% by volume is preferably less than 10 μm, and the cumulative particle size distribution of 90% by volume. It is more preferable that the particle size of is less than 7 μm.

  As (C-1) micron-order inorganic particles, in order to obtain high strength, irregularly shaped particles, plates, (C-2) sub-micron order inorganic particles, and (C-3) nano-order inorganic particles are used. Agglomerated and clustered particles produced by agglomeration and heat treatment or coagulation treatment as necessary are preferably used. The reason why high strength can be obtained is presumed to be that the use of inorganic particles having the above-described shape has the effect of stopping the development of cracks at the time of destruction. The average particle diameter is preferably 1 to 9 μm, and particularly preferably the average particle diameter is 2 to 5 μm. If the average particle diameter of (C-1) is too large, the abrasiveness of the cured product of the curable composition may be reduced. Particles having a particle diameter of 10 μm or more are 3% by mass or less, preferably 1% by mass or less, in (C-1) micron order inorganic particles. When many coarse particles of 10 μm or more are contained, it tends to be a starting point of breakage and the strength may be lowered.

  In addition, the average particle diameter of the inorganic particles in the present invention is an image of an equivalent circle diameter of a primary particle diameter (a diameter of a circle having the same area as that of the target particle) from an image taken by a scanning or transmission electron microscope. The one measured by analysis. As an electron microscope image used for measurement, an image that is clear and bright and capable of discriminating the outline of the particle is used. Use analysis software. Moreover, the average particle diameter and average uniformity of these primary particles are calculated from the primary particle diameter measured as described above by the following formula.

  Here, the number of particles (n), the maximum length of the particles is the major axis (Li), and the diameter in the direction perpendicular to the major axis is the minimum width (Bi). When calculating these values, it is necessary to measure at least 40 or more particles in order to maintain measurement accuracy, and it is desirable to measure 100 or more particles.

  (C-2) The submicron order inorganic particles are preferably spherical or substantially spherical in order to obtain a high filling rate. In addition, the substantially spherical shape here means that the average degree of homogeneity obtained in the image analysis of the captured image of the scanning or transmission electron microscope is 0.6 or more. The average uniformity is more preferably 0.7 or more, and further preferably 0.8 or more. The average particle diameter is preferably 0.1 to 0.6 μm, and more preferably 0.3 to 0.5 μm.

  (C-3) The nano-order inorganic particles are preferably spherical or substantially spherical in order to obtain a high filling rate. In addition, the substantially spherical shape here means that the average degree of homogeneity obtained in the image analysis of the captured image of the scanning or transmission electron microscope is 0.6 or more. The average uniformity is more preferably 0.7 or more, and further preferably 0.8 or more. A preferable average particle diameter is 0.01 to 0.09 μm, and more preferably 0.05 to 0.08 μm.

  The blending ratio of (C-1), (C-2), and (C-3) may be used at any ratio without particular limitation, but the preferred range is (C) 100% by mass of the total amount of inorganic particles. (C-1) is 30 to 80% by mass, more preferably 40 to 70% by mass, (C-2) is 10 to 50% by mass, more preferably 20 to 40% by mass, and (C-3). ) Is 0 to 30% by mass, more preferably 10 to 20% by mass.

  (C) As inorganic particles, inorganic particles other than (C-1), (C-2), and (C-3) may be included within a range not inhibiting the effects of the present invention.

  These (C) inorganic particles may be inorganic particles produced by any known method. For example, as long as it is an inorganic oxide or composite oxide, it may be produced by any method of a wet method, a dry method, a melting method, and a sol-gel method, and further pulverizing, crushing, drying, It may be manufactured through processing steps such as agglomeration, heating, baking, and cooling. When agglomerated or clustered particles are to be agglomerated or clustered, after forming agglomerated particles using a small amount of binder resin or silane coupling agent, the binder resin or silane is produced by the action of thermal energy or the like. The coupling agent may be strongly agglomerated by curing and polymerizing, or primary particles may be agglomerated strongly by heating to a temperature of 100 ° C. or higher without using them. Inorganic particles obtained by such a method may be fired at a temperature of 500 to 1000 ° C. in order to impart surface stability. Since firing has an effect of reducing active groups such as silanol groups on the surface of the inorganic particles, it is possible to suppress a decrease in strength after immersion in water. During firing, some of the inorganic particles may aggregate. In this case, agglomerated particles can be broken into primary particles using a jet mill, a vibration ball mill, or the like, and the particle size can be adjusted to a predetermined range before use. By treating in this way, the abrasiveness of the composition when used as a dental composition is improved.

  (C) Inorganic particles (A) In order to improve wettability with respect to the polymerizable monomer, cause a covalent bond with the polymerizable monomer, and suppress strength increase and strength reduction after immersion in water The surface treatment is preferably performed with a surface treatment agent.

  As the surface treating agent, a conventionally known one can be used without any limitation. Examples of suitable surface treatment agents include vinyltriethoxysilane, vinyltrimethoxysilane, vinyl-tris (β-methoxyethoxy) silane, γ-methacryloyloxypropyltrimethoxysilane, κ-methacryloyloxide decyltrimethoxysilane, β -(3,4-epoxycyclohexyl) -ethyltrimethoxysilane, γ-glycidoxypropyl-trimethoxysilane, N-β- (aminoethyl) -γ-aminopropyl-trimethoxysilane, γ-ureidopropyl-tri Examples include silane coupling agents such as ethoxysilane, γ-chloropropyltrimethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, and methyltriethoxysilane. In particular, since the water resistance is high, it is preferable to use a silane coupling agent having an aromatic ring or a silane coupling agent having a fluoroalkyl group. Specific examples of such silane coupling agents include 3- (4-methacryloyloxyphenyl) propyltrimethoxysilane, polyfluoroalkyltrimethoxysilane and the like. Also, depending on the inorganic particles used, aluminate coupling agents, titanate coupling agents, and zirconate coupling agents may be preferred, but for these, the optimum surface treatment agent is selected as appropriate while evaluating physical properties. can do.

  (C) There is no restriction | limiting in particular in the usage-amount of the surface treating agent used for the surface treatment of an inorganic particle, What is necessary is just to select the optimal usage-amount from the result of some preliminary experiments. If it is too much or too little, the strength after immersion in water may decrease. If the usage-amount of a suitable surface treating agent is illustrated, it will be 1-30 mass parts of said surface treating agents with respect to 100 mass parts of (C) inorganic particles.

  The surface treatment method is not particularly limited, and a known method is adopted without limitation. For example, (C) inorganic particles and a surface treatment agent are dispersed and mixed in a suitable solvent using a ball mill or the like, dried by an evaporator or air-dried, and then heated to 50 to 150 ° C. There is a way to do it. Furthermore, there is a method in which (C) the inorganic particles and the surface treatment agent are heated to reflux for several hours in a solvent such as alcohol. Furthermore, there are a method of graft polymerization of a surface treatment agent on the particle surface, a method of integral blending, and the like.

  The surface treatment may be performed on the primary particles when using aggregated and clustered particles produced by aggregating inorganic particles as (C) inorganic particles and performing heat treatment or coagulation treatment as necessary. You may go to the agglomerated particles. For example, when producing aggregated particles by spray drying, it is efficient to perform surface treatment simultaneously with this treatment.

<Other optional components>
The curable composition in the present invention may contain any component in addition to (A) a polymerizable monomer, (B) a polymerization catalyst, and (C) inorganic particles. Examples thereof include a polymerization inhibitor, a chain transfer agent, a fluorescent agent, an ultraviolet absorber, an antioxidant, a pigment, an antibacterial agent, and an X-ray contrast agent. As these optional components, those known for use in dental curable compositions can be used.

<Method for preparing curable composition and method for producing cured body>
As a method for adjusting the curable composition in the present invention, a known method can be used. In general, the above-mentioned essential components and optional components to be added as required can be sufficiently kneaded and obtained by defoaming the resulting paste to remove bubbles. For example, (A) polymerizable monomer, (B) polymerization catalyst, (C) inorganic particles, and other optional components are mixed, dissolved and dispersed by stirring and kneading, weighing, mold filling, defoaming, attaching Perform operations such as shape.

  The obtained curable composition is preliminarily polymerized by heating or light as necessary, and then (B) an operation such as external energy application according to the initiation mechanism of the polymerization catalyst, for example, a thermal polymerization initiator is used. In this case, polymerization and curing can be performed by heating at 60 ° C. to 100 ° C. and, if necessary, pressurizing and heating with an inert gas such as nitrogen, argon, or carbon dioxide, to produce a cured product. In addition, the obtained cured body can be subjected to post-treatment such as polishing, surface loading, and printing. As described above, a desired resin material for dental cutting can be obtained by polymerizing and curing a curable composition to obtain a cured product, followed by a heat treatment described later.

<Heat treatment method>
According to the method for producing a resin material for dental cutting work of the present invention, it is possible to impart desired physical properties by performing heat treatment at a specific temperature on the cured body of the curable composition described above.

  The temperature of the heat treatment is preferably performed at a temperature between −50 ° C. and + 100 ° C. of the loss tangent peak temperature of the cured product of the curable composition, and is a temperature between −30 ° C. and + 50 ° C. Is more preferable. When the temperature is lower than the above temperature range, the effect of the heat treatment is reduced. Is also undesirable because it tends to be high. Furthermore, the temperature at which the heat treatment is carried out is preferably 20 ° C. or higher, more preferably 30 ° C. or higher than the temperature at which the cured product of the curable composition is polymerized. When the heat treatment temperature is higher than the polymerization temperature, the effect of the heat treatment is easily obtained. In addition, when the temperature of the heat treatment is 100 ° C. or higher, the effect of the heat treatment is more easily obtained. It is preferable to perform the heat treatment at. The heating time is preferably 1 hour or longer, and more preferably 1.5 hours or longer. In addition, since excessively long heating promotes thermal degradation of the resin, it is preferably within 200 hours, more preferably within 150 hours, and more preferably within 100 hours in order to suppress resin burns and discoloration. It is most preferable that it is. Although there is no restriction | limiting in the atmosphere at the time of heating, in order to prevent the color tone change by oxidation deterioration, it is preferable to heat-process in inert gas atmosphere, such as nitrogen. The apparatus used for the treatment is not limited as long as it can heat the cured body to a desired temperature, but in general, the forced convection oven has higher internal temperature uniformity than the natural convection type. preferable. Also, there is no limitation on the method for setting the inert gas atmosphere, but for example, a sealed container for separately containing the cured body may be used, and the oven itself has a sealed structure to replace the internal atmosphere. You may do it. Even when the oven is not sealed, a method of continuously flowing the atmospheric gas can be used. The loss tangent peak temperature of the cured product of the curable composition was obtained by a dynamic viscoelasticity test, and was measured according to the method described in “Plastics—Test method for dynamic mechanical properties—Part 7” described in JIS K7244-7. It is possible to measure.

  The heat treatment step in the production method of the present invention exerts the above-mentioned effect by being performed when the curable composition is in the state of a cured body, but the heat treatment conditions of the present invention are applied to the curable composition. By performing heat treatment subsequent to heat polymerization under satisfying conditions, it is also possible to carry out the polymerization curing and the heat treatment in the production method of the present invention all at once. In that case, the time after reaching the desired heat treatment temperature may be set as the heat treatment time. Although polymerization curing and heat treatment can be performed collectively, it is excellent from the viewpoint of efficiency, but from the viewpoint of releasing the internal stress of the resin, after polymerization and cooling, it is taken out from the mold used for polymerization, and the polymerization process It is preferable to implement a heat treatment step as a separate step. By making the heat treatment in the production method of the present invention a step different from polymerization, the internal stress can be released more effectively and a stable bending strength can be obtained.

  In either case described above, the temperature profile of the “heating process” and “cooling process” of the heat treatment can be arbitrarily determined. Regarding the temperature raising process, particularly when heat-treating the curable composition before curing, the polymerization treatment is first performed by maintaining the temperature for a certain period of time at or below the temperature condition of this patent, and then the heating according to the present invention. It is possible to take a temperature profile of temperature rise that raises the temperature to the processing conditions. With respect to the temperature lowering process, it is possible to suppress the occurrence of internal strain due to the contraction during the temperature lowering by lowering the temperature as slowly as possible. As such a form, a rate of 20 ° C./min or less is preferable, and a rate of 10 ° C./min or less is more preferable.

<Dental cutting resin material>
The “resin material for dental cutting” obtained by the production method of the present invention has a high initial strength and suppresses a decrease in strength after being immersed in water. It is used for material applications and is suitable as a cutting resin material. The cutting method is characterized in that even a material having high strength and hardness can be processed by mechanical cutting. Specifically, the resin material for dental cutting obtained by the production method of the present invention includes dentures, denture bases, artificial teeth, implant fixtures, abutments, superstructures, inlays, onlays, crowns, bridges, and abutments. It can be suitably used for building materials and the like, and is particularly suitable as a material for crown and bridge because it has high strength in the initial stage and high strength even after being immersed in water.

  The bending strength of the resin material for dental cutting obtained by the production method of the present invention after 7 days of immersion in 37 ° C. water is preferably 240 MPa or more, and more preferably 250 MPa or more. Further, the residual strength rate after immersion in water is preferably 85% or more, and more preferably 90% or more. In addition, the measuring method and measuring conditions of bending strength are as having described in the Example mentioned later.

  The size of the resin material for dental cutting obtained by the production method of the present invention is desirably an appropriate size that can be set in a commercially available dental CAD / CAM system. Examples of desirable sizes include, for example, a 40 mm × 20 mm × 15 mm prismatic shape suitable for the creation of a single-tooth defect bridge; a 17 mm × 10 mm × 10 mm prismatic shape suitable for the production of inlays and onlays; 14 mm × 18 mm × 20 mm, 10 mm × 12 mm × 15 mm Examples include a prismatic shape of 5 mm × 14.5 mm × 18 mm; a long span bridge, a disk shape having a diameter of 90 to 100 mm and a thickness of 10 to 28 mm, which is suitable for creating a denture base. The “resin material for dental cutting work” obtained by the production method of the present invention has high strength and is suitable for the production of larger workpieces, but is not limited to these sizes, and is not limited to the purpose or device. What is necessary is just to determine suitably by the restrictions of attachment, etc.

  The “resin material for dental cutting” of the present invention may be provided with a fixture for fixing to a cutting machine or a shape necessary for fixing. The fixture is not particularly limited as long as it has a shape that can be connected to a cutting machine. Stainless steel, brass, aluminum, etc. are used for the material of the fixture. The fixing method of the fixing tool to the resin material for dental cutting processing may be a known method such as adhesion, fitting, screwing, etc. There is no particular limitation on the above-mentioned adhesion method, and isocyanate-based, epoxy-based, urethane-based, silicone-based Various commercially available adhesives such as acrylic can be used.

  A method for producing a cut product using the dental cutting resin material of the present invention will be described below.

  First, a pedestal is formed in a patient's oral cavity by a dentist. For example, the abutment is formed by shaving teeth. Next, an impression of the abutment, adjacent teeth, counter teeth, etc. is taken by the dentist. The impression is taken using an alginate impression material, a silicone impression material, a digital impression device, or the like. Thereafter, a dental technician or dentist creates a plaster model from the acquired impression, and the shape of the plaster model is digitized using a scanning machine or the like. Alternatively, a digital model is created from data obtained by a digital impression.

  Next, digital data of the prosthesis is created using design software based on the measurement data of the plaster model. Based on the digital data of the prosthesis, digital data for cutting with a cutting machine is created. At this time, it is confirmed on software that the cut portion of the dental cutting block preferably obtained by the manufacturing method of the present invention has a sufficient size for the prosthesis to be produced.

  Thereafter, the dental cutting block obtained by the manufacturing method of the present invention is installed in a cutting machine, and cutting is performed. It is preferable to use a commercially available dental cutting machine. To perform the cutting process, a cutting tool (bar) and a cutting process (CAM) software are required. The CAM software controls the movement of the cutting tool and the movement of the block fixed through the fixing tool, and typical parameters include position information, feed speed, and rotation speed. The cutting tool is preferably a general dental cutting bar. It is preferable that a coating such as a diamond coat is applied as a countermeasure against wear. Generally, a cutting bar is used in combination with a plurality of cutting bars according to the stage of cutting, such as for rough cutting, medium cutting, and fine cutting. For convenience, a rough crown shape is formed using rough cutting (for example, 2 mm diameter), and then the surface texture is smoothed using fine cutting (for example, 0.8 mm diameter), or a fine occlusal surface or the like. To express a simple structure. When the cutting by the cutting machine is completed, the sprue portion remaining in the dental cutting block is cut off. After the shape correction and polishing are performed, pretreatment of the inner surface of the prosthesis (roughening by sandblasting or the like) is performed as necessary. The prosthesis produced in this manner is pretreated on the inner surface (primer application or the like) as necessary, and then adhered to a support in the patient's oral cavity.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The materials and test methods used in the examples and comparative examples are shown below.

<(A) Polymerizable monomer>
(A-1) HD: 1,6-hexanediol dimethacrylate (A-2) NPG: neopentyl glycol dimethacrylate (A-3) DCP: tricyclodecane dimethanol dimethacrylate (A-4) ND: 1, 9-nonanediol dimethacrylate (A-5) TEGGMA: triethylene glycol dimethacrylate (A-6) UDMA: 1,6-bis (methacrylethyloxycarbonylamino) trimethylhexane (A-7) D-2.6E : 2,2-bis ((4- (meth) acryloyloxyethoxy) phenyl) propane (ethylene oxide 2.6 mol)

<(B) Polymerization catalyst>
BPO: Benzoyl peroxide

<(C) Inorganic particles>
(C-1) A treated product of γ-methacryloyloxypropyltrimethoxysilane of amorphous silica zirconia having an average particle size of 3.0 μm.
(C-2) Gamma-methacryloyloxypropyltrimethoxysilane treated with spherical silica zirconia having an average particle diameter of 0.4 μm (C-3) γ-methacryloyloxypropyltrimethoxysilane having an average particle diameter of 0.08 μm spherical silica titania Processed product

(Measurement of loss tangent peak temperature)
According to the method described in “Plastics—Test Method for Dynamic Mechanical Properties—Part 7” described in JISK7244-7, the temperature is measured from 25 ° C. to 200 ° C. by a dynamic viscoelasticity measurement system ARES manufactured by TA Instruments. The dynamic viscoelasticity test was performed under the conditions of a temperature rising rate of 3 ° C./min, a frequency of 10 Hz, a clamp distance of 10 mm, and a dynamic strain of 0.01%. As a test piece, a mold having a size of 25 mm × 5 mm × 1 mm was filled with a curable composition, and was prepared by polymerization and curing by heating at 90 ° C. for 15 hours under 0.4 MPa nitrogen pressure. The loss tangent tan δ was output, and the temperature of the loss tangent peak was determined from the inflection point of the graph.

(Bending test)
A 1.2 mm × 4.0 mm × 18 mm test piece was cut out from a dental cutting resin material or a cured product of a curable composition, and each surface of the test piece was finished with P2000 water-resistant abrasive paper. The prepared test piece was immersed in purified water and stored in a 37 ° C. incubator for 7 days. Using a universal testing machine Autograph (manufactured by Shimadzu Corporation), a three-point bending test on a 4.0 mm x 18 mm surface in a room temperature atmosphere at a fulcrum distance of 12.0 mm and a crosshead speed of 1.0 mm / min Went. For each of 10 test pieces before and after immersion in water, the bending strength [MPa] was calculated from the following formula and obtained as an average value.

Bending strength [MPa] = 3FS / (2bh ² )
Here, F: maximum load applied to the test piece [N], S: distance between supporting points [mm], b: width of the test piece measured just before the test [mm], h: test piece measured just before the test The thickness is [mm].

(Color change)
The samples before and after the heat treatment were visually evaluated, and the color difference before and after the heat treatment was evaluated in four stages: ◎ (very good), ○ (good), △ (acceptable), and × (bad).

Example 1
(A-1) HD 15 parts by mass, (A-6) UDMA 15 parts by mass, (A-7) D-2,6E70 parts by mass, and BPO 1.0 part by mass are mixed to obtain a curable polymerizable monomer composition. Was prepared. Moreover, (C-1) 60 mass parts, (C-2) 28 mass parts, and (C-3) 12 mass parts were mixed, and the inorganic particle composition was prepared. To 84% by mass of the inorganic particle composition, 16% by mass of the curable polymerizable monomer composition is added and mixed until uniform using a planetary mixer. A curable composition was prepared. This curable composition was filled in a 14.5 mm × 14.5 mm × 18 mm mold, subjected to nitrogen pressurization at 0.4 MPa in a pressurized container, and left in a 90 ° C. heating apparatus. In this state, it was polymerized and cured by heating for 15 hours. After cooling to room temperature at a cooling rate of 20 ° C./min, the cured product was taken out from the mold. The obtained cured product was again subjected to 0.4 MPa nitrogen pressurization in a pressure vessel, left still in a heating device at 160 ° C., subjected to heat treatment for 48 hours, and then cooled to room temperature at a cooling rate of 20 ° C./min. The resin material for dental cutting was obtained by cooling, and the bending test was done. The results of the bending test are shown in Table 1.

(Examples 2 to 19)
A bend test was performed in the same manner as in Example 1 except that the curable composition and the heat treatment conditions were changed to those shown in Table 1.

(Example 20)
The curable composition was changed to the one shown in Table 1, filled into a 14.5 mm × 14.5 mm × 18 mm mold, brought to 0.4 MPa nitrogen pressure in a pressure vessel, and 170 in a heating device. A bend test was performed in the same manner as in Example 1 except that polymerization and heat treatment were performed at a temperature of 0 ° C. in a lump.

(Examples 21 to 23)
A bend test was performed in the same manner as in Example 1 except that the curable composition and the heat treatment conditions were changed to those shown in Table 1.

(Comparative Examples 1-5)
A bend test was performed in the same manner as in Example 1 except that the curable composition and the heat treatment conditions were changed to those shown in Table 1.

Claims (5)

  (A) Polymerizable monomer, (B) Polymerization catalyst, (C) Loss tangent of the cured product in a method for producing a resin material for dental cutting which is a cured product of a curable composition comprising inorganic particles A method for producing a resin material for dental cutting, wherein the heat treatment is performed at a peak temperature between −50 ° C. and + 100 ° C. for 1 hour to 200 hours.   The method for producing a resin material for dental cutting according to claim 1, wherein the heat treatment is performed at a temperature between -30 ° C and + 50 ° C of the loss tangent peak temperature of the cured body.   The method for producing a resin material for dental cutting according to claim 1 or 2, wherein the heat treatment is performed at a temperature higher than the polymerization temperature of the curable composition.   The method for producing a resin material for dental cutting according to any one of claims 1 to 3, wherein the heat treatment is performed at atmospheric pressure to 0.9 MPa in an inert gas atmosphere.   The method for producing a resin material for dental cutting according to any one of claims 1 to 4, wherein a cooling rate after the heat treatment is 20 ° C / min or less.