JP2023046724A - Production method for light-curable composition - Google Patents

Abstract

To provide a method for suppressing agglomeration that occurs when a powder composition containing an α-diketone compound and an amorphous resin powder, which is suitably used as a powder for light-curable powder-liquid denture base backing materials, is stored for a long period of time, and in addition, to provide an efficient method of manufacturing powder-liquid denture base backing materials with high storage stability.SOLUTION: A raw material powder containing an α-diketone compound and an amorphous resin powder is treated at a heat treatment temperature of 40°C or higher and lower than the glass transition point of the amorphous resin, with the result that amorphous resin particles are positively agglomerated and the α-diketone compound is adhered to surfaces of the agglomerated particles by sublimation and coagulation. After that, the agglomerated particles are pulverized, and the obtained powder composition is used as a powder material.SELECTED DRAWING: None

Description

The present invention relates to a method for producing a photocurable composition. More particularly, it relates to a method for producing a photocurable composition suitable for a photopolymerization type denture base relining material.

As a material for repairing dentures that are incompatible with the patient's oral mucosa, there is a denture base relining material. A powder-liquid type consisting of a liquid material whose main component is a body is widely known. Such a powder-liquid type denture base lining material is used by mixing a powder material and a liquid material to obtain a paste, applying the paste on the denture, and after ensuring compatibility with the oral mucosa, it is finally cured. There are two types, chemical polymerization type and photopolymerization type, depending on the type of curing catalyst used.

That is, in the chemical polymerization type, radicals are generated by the coexistence of a chemical polymerization initiator and a polymerizable monomer, and polymerization and curing occur. Hardening occurs. On the other hand, in the photopolymerization type, polymerization and curing are performed by generating radicals by irradiating the photopolymerization initiator with light that excites it (hereinafter also simply referred to as “activating light”). The paste obtained after mixing the material and the liquid material is piled up on the denture, and after making it compatible with the oral cavity, the final curing is performed outside the oral cavity by light irradiation using a special light irradiation device. For this reason, with the photopolymerization type, the denture base lining material is removed from the oral cavity in a state in which rubber elasticity has been developed before the final curing is performed, so even in cases where there is an undercut, the patient does not experience pain. It is possible to take measures for

For the photopolymerization type denture base relining material, a combination of an α-diketone compound and a tertiary amine compound is used as the photopolymerization initiator for the purpose of enhancing the stability of the material during storage. It is common practice to use both powders and liquids separately.

Examples of such a photopolymerization type denture base relining material include (a) a polymerizable monomer, (d) a tertiary amine compound, and (e) an acid dissociation constant in water (25°C) of (b) resin particles having a weight average molecular weight of 3.0 to 2,000,000 as measured by gel permeation chromatography; , and (c) a powder made of an α-diketone compound (see Patent Document 1). Dedicated light using a light source capable of irradiating light including a wavelength range of about 500 nm (which is the main absorption range of α-diketone compounds) with an output such that the light intensity in the wavelength range is about 50 to 6000 mW/cm ² done using an irradiator.

Japanese Patent No. 6779506

In the powder-liquid type using a photopolymerization initiator composed of a combination of an α-diketone compound and a tertiary amine compound as described above, the distribution of the catalyst component to the powder material and the liquid material is basically arbitrary. , as in the denture base relining material described in Patent Document 1, the α-diketone compound is often blended with the powder material and the tertiary amine compound is blended with the liquid material and packaged.

However, according to the study of the present inventors, in the denture base relining material as described in Patent Document 1, the powder material containing resin particles and an α-diketone compound cannot be used for a long period of time at room temperature. It became clear that the powder material may aggregate due to storage or storage in a state where the temperature suddenly rises.

If the powder material agglomerates, it becomes difficult to dissolve the agglomerated components when the powder material and the liquid material are mixed to prepare a paste for use as a denture base relining material. Then, the speed of increase in the viscosity of the paste changes from the designed value, which causes problems such as a poor operational feeling and the material becoming brittle due to hardening of the cohesive components left undissolved.

Accordingly, it is an object of the present invention to provide a technology for preventing agglomeration of a powder containing resin particles and an α-diketone compound during storage.

The present invention is intended to solve the above problems, and a first form of the present invention comprises amorphous resin powder: 100 parts by mass and α-diketone compound powder: 0.05 to 1.0 parts by mass. A raw material powder preparation step of preparing a raw material powder containing Coarsely aggregated particles in which an amorphous resin constituting A method for producing a powder composition, characterized by obtaining a powder composition containing aggregated particles that are pulverized coarsely aggregated particles.

In the production method of the above embodiment (hereinafter also referred to as “the composition production method of the present invention”), the raw material powder has an average particle size (50% volume average particle size) measured by laser diffraction method of 1 to 300 μm. and an α-diketone compound powder having an average particle size (50% number average particle size) measured by a laser diffraction method within the range of 50 to 300 μm.

In addition, the raw material powder contains inorganic fine particles having an average particle size (50% volume average particle size) of 0.01 to 0.2 μm as measured by a laser diffraction method, and resin powder: 0 parts by mass. It is preferable to contain 0.03 to 0.3 parts by mass.

Furthermore, in the agglomeration step, it is preferable to obtain coarsely agglomerated particles by allowing the raw material powder to stand still under the normal pressure and the heat treatment temperature.

A second form of the present invention is a photopolymerization type comprising a liquid material containing a polymerizable monomer and a tertiary amine compound, and a powder material consisting of a powder composition containing resin particles and an α-diketone compound. A method for producing a denture base relining material according to the above, characterized in that the powder composition constituting the powder material is produced by the composition production method of the present invention. It is a manufacturing method (hereinafter also referred to as “the manufacturing method of the lining material of the present invention”).

According to the method for producing a composition of the present invention, it is possible to efficiently produce a powder composition that does not easily aggregate even after long-term storage and that can be suitably used as a powder material for a denture base relining material. . Then, the (light-curing type) denture base relining material produced by the relining material production method of the present invention, which uses the powder composition produced by the production method as a powder material, can be stored at room temperature for a long period of time. Because it is difficult for the powder material to aggregate due to an unexpected temperature rise, the storage stability is excellent, and it is possible to maintain the feeling of use and curing properties equivalent to those in the initial stage of production for a long period of time.

In order to solve the above problems, the inventors of the present invention first investigated the agglomeration properties of a powder material containing resin particles and an α-diketone compound. As a result, the α-diketone compound in the powder material has a sublimation property, and after sublimation, the α-diketone compound solidifies on the surface of the resin particles in the powder material system, thereby fixing the adjacent resin particles. , it was found that the powder material was agglomerated. Therefore, based on this finding, further investigations were carried out on methods for controlling the sublimation-coagulation properties of α-diketone compounds. The inventors have found that (the pulverized material) is difficult to re-agglomerate, and have completed the present invention.

Although the reason why such excellent effects are obtained is not necessarily clear, the present inventors presume as follows. That is, immediately after mixing the resin particles and the α-diketone compound, the resin particles and the α-diketone compound are dispersed and are in a state of no aggregation. The diketone compound diffuses to the surroundings and then segregates on the surface of the resin particles, thereby becoming widely and uniformly dispersed. ) It is thought that slight entanglement of polymer chains on the surface is fixed. When the coarsely aggregated particles are pulverized, the surfaces of most of the resulting pulverized particles (aggregated particles) are (at least partly) covered with the α-diketone compound, and the surface polymers of the resin particles It is presumed that the contact between was inhibited and aggregation became difficult to occur.

As described above, the composition manufacturing method of the present invention and the relining material manufacturing method of the present invention use resin powder and α - It has a great feature in that the raw material powder containing the diketone compound powder is aggregated once and then pulverized. The raw materials constituting the raw material powder are not particularly different from those used in the conventional powder material. Further, the liquid material in the relining material obtained by the relining material manufacturing method of the present invention is not particularly different from the conventional liquid material (containing the polymerizable monomer and the tertiary amine compound). Including these, the present invention will be described in detail below.

In this specification, unless otherwise specified, the notation "x to y" using numerical values x and y means "x or more and y or less". In such notation, when only the numerical value y is given a unit, the unit is also applied to the numerical value x. Moreover, in this specification, the term "(meth)acrylic" means both "acrylic" and "methacrylic". Similarly, the term "(meth)acrylate" means both "acrylate" and "methacrylate", and the term "(meth)acryloyl" means both "acryloyl" and "methacryloyl".

1. Composition manufacturing method of the present invention The composition manufacturing method of the present invention includes the following (1) raw material powder preparation step, (2) agglomeration step, and (3) pulverization step, and the (coarse) obtained in the pulverization step It is characterized by obtaining a powder composition containing agglomerated particles (which is a pulverized product of agglomerated particles). Each of these steps will be described below.

(1) Raw material powder preparation step In the raw material powder preparation step, raw material powder containing 100 parts by mass of amorphous resin powder and 0.05 to 1.0 parts by mass of α-diketone compound powder is prepared. do. As the raw material powder, as long as it satisfies the above conditions, the powder material of the powder-liquid type lining material using a photopolymerization initiator may be used as it is, or it may be prepared separately. When separately prepared, a predetermined amount of each component may be mixed. Mixing can be preferably carried out using, for example, an oscillating mixer in which the container itself rotates, a blade stirring device using rotating blades, or the like. Since the amount of the α-diketone compound contained in the raw material powder is small compared to the amount of the amorphous resin powder, in consideration of the ease of handling the powder, etc., prior to mixing, It may be mixed with a part of the amorphous resin powder to form a masterbatch.
The various raw materials and their compounding amounts, which are components of the raw material powder, will be described below.

(1-1) Amorphous resin powder Amorphous resin powder suitably used as raw material powder includes polymethyl methacrylate, polyethyl methacrylate, polypropyl methacrylate, polybutyl methacrylate, and methacrylic. Amorphous resin particles made of methyl acid-ethyl methacrylate copolymer, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-styrene-butadiene copolymer and the like can be mentioned. These amorphous resin particles may be used alone or in combination of multiple types. When the powder composition, which is the object of the composition manufacturing method of the present invention, is used for dental use, particularly as a denture base relining material, it has good solubility in liquid materials and viscosity increase performance in a paste state. It is preferable to use polyethyl methacrylate because of its goodness.

These amorphous resins may be crosslinked or non-crosslinked, but in the case of denture base relining materials, non-crosslinked resin particles are generally used. At this time, the weight average molecular weight of the amorphous resin measured by gel permeation chromatography (GPC) is 3 to 200 from the viewpoint of the solubility of the resin particles in the liquid material and the appropriate timing of viscosity increase of the paste. 10,000 is preferable, and the range of 30,000 to 1,000,000 is preferable because the aggregates obtained in the agglomeration step can be easily pulverized (crushed).

The shape of the resin particles constituting the amorphous resin powder is not particularly limited, and may be spherical or amorphous. Moreover, the particle size is not particularly limited, and a plurality of resin particles having different average particle sizes may be used together.

However, when the powder composition, which is the object of the composition manufacturing method of the present invention, is for dental use, particularly for denture base relining material, the average particle size measured by laser diffraction (50% volume average particle size It is preferable to use amorphous resin particles having a diameter) of 1 to 300 μm. Furthermore, the average particle size is more preferably 5 to 300 μm because the aggregates obtained in the aggregation step can be easily pulverized (crushed). Moreover, the resin (primary) particles are preferably spherical particles having a sphericity of 0.6 or more. The BET specific surface of the amorphous resin powder measured by the nitrogen adsorption method is usually in the range of 0.5 to 10 m ² /g.

(1-2) α-Diketone Compound The α-diketone compound is a compound having a maximum absorption wavelength of 350 to 700 nm and having a function of generating active species such as radicals effective for polymerization by actinic light. Active species are usually the result of energy transfer or electron transfer between polymerizable monomers or other substances.

Examples of α-diketone compounds suitable for use in the present invention include camphorquinone, benzyl, camphorquinonesulfonic acid, acenaphthenequinone, 1,2-naphthoquinone, 1,2-phenanthrenequinone, 9,10-phenanthrenequinone, and the like. can be mentioned. Among these, camphorquinone is particularly preferably used for dental use, particularly for use as a relining material for denture bases, due to its high polymerization activity, high safety to the living body, and the like. Among them, it is preferable to use one having an average particle size (50% number average particle size) of 50 to 300 μm, particularly 50 to 200 μm, from the viewpoint that the agglomeration step can be performed quickly. In addition, the average particle diameter here means the value measured by the laser diffraction method.

The particle size of the α-diketone compound can be controlled by adjusting the conditions of pulverization such as dry pulverization or wet pulverization, and the average particle size can be controlled in advance by using a sieve with a desired opening. can be done.

If the content of the α-diketone compound in the raw material powder is too large, the cured product tends to become soft when used as a powder material for a denture base relining material. Therefore, the amount of the α-diketone compound should be 0.05 to 1.0 parts by mass with respect to 100 parts by mass of the amorphous resin powder.

(1-3) Inorganic Fine Particles Inorganic fine particles are preferably blended into the raw material powder for the purpose of facilitating pulverization (pulverization) in the pulverization step and enhancing the effect of preventing (re)aggregation. It is presumed that the reason why the pulverization becomes easier is that the inorganic fine particles act as starting points for the pulverization during the pulverization because the powder material agglomerates in a state where the inorganic fine particles are interposed between the resin particles. In addition, it is speculated that reaggregation is suppressed because, in the pulverized powder material, the presence of inorganic fine particles between the resin particles covered with the α-diketone compound makes it difficult for the resin particles to come into contact with each other. be done.

When inorganic fine particles are blended, the inorganic particles are preferably sufficiently smaller than the resin particles constituting the amorphous resin powder, and the average particle diameter (50% volume average particle diameter) measured by laser diffraction is 0. It is preferably between 0.01 and 0.2 μm. From the viewpoint of effectiveness, the amount to be added is preferably 0.03 to 0.3 parts by mass with respect to 100 parts by mass of the amorphous resin powder.

Suitable inorganic fine particles include quartz, silica, alumina, silica titania, silica zirconia, lanthanum glass, barium glass, strontium glass and the like. Hydroxides such as calcium hydroxide and strontium hydroxide; or oxides such as zinc oxide, silicate glass and fluoroaluminosilicate glass; cation-eluting inorganic particles can also be preferably used. Among them, it is preferable to use silica fine particles because the desired particle size is easily available.

It is desirable to treat the inorganic fine particles described above with a surface treatment agent represented by a silane coupling agent in order to improve compatibility with the polymerizable monomer and improve mechanical strength and water resistance. The surface treatment may be performed by a known method, and examples of the silane coupling agent include methyltrimethoxysilane, methyltriethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, vinyltriethoxysilane, Vinyltris(β-methoxyethoxy)silane, γ-methacryloyloxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, hexamethyldisilazane and the like are preferably used.

(1-4) Other Ingredients Organic pigments, inorganic pigments, ultraviolet absorbents, and the like may be added to the raw material powder depending on the purpose within a range that does not impair the performance. In addition, organic peroxides such as benzoyl peroxide may be added as other initiator components.

(2) Aggregation step In the aggregation step, the raw material powder is treated at a heat treatment temperature of 40°C or higher and lower than the glass transition point Tg of the amorphous resin to convert the amorphous resin powder into Coarsely agglomerated particles obtained by aggregating a constituent amorphous resin and having an α-diketone compound present on the surface of the coarsely agglomerated particles are obtained. When the heat treatment temperature is less than 40°C, it takes a long time for aggregation, and when it exceeds the glass transition point, aggregation may occur only between the amorphous resin particles, or the sublimated α-diketone compound may dissipate. It is difficult to obtain the desired effect by doing so. From the viewpoint of effect, it is preferable to heat-treat at a temperature in the range of 40° C. or higher and 20° C. lower than Tg to 5° C. lower than Tg. In the agglomeration step, the sublimation-coagulation of the α-diketone compound caused by the heat treatment causes the α-diketone compound to be present on the surface of the obtained coarsely aggregated particles.

The glass transition point of the amorphous resin: Tg is well known in the literature and books, and the Tg of a general-purpose homopolymer can be easily measured using a differential scanning calorimeter if it is unknown. .

In order to prevent the α-diketone compound from sublimating and dissipating out of the system, the heat treatment may be carried out by placing the raw material powder in a sealed container and then storing it in a thermostatic chamber whose temperature can be adjusted. Container materials include resin containers such as polystyrene, polyethylene, polypropylene, ABS resin, polyvinyl chloride, and PET resin, as well as glass, enamel, stainless steel, and porcelain. For these reasons, the resin container is preferable. In addition, from the viewpoint of protection from ambient light, it is preferable to add a black pigment to the container to be used to enhance light-shielding properties. Examples of black pigments include carbon black, perylene black, aniline black, and iron oxide. As the container, it is also possible to use an oscillating mixer equipped with a heating device. In this case, the pulverization step can be performed as it is after the agglomeration step is completed.

The heat treatment is preferably carried out by allowing the raw material powder to stand under normal pressure and the heat treatment temperature.

The heat treatment may be terminated when the formation of coarse particles having a particle diameter of 2 mm or more, preferably 3 mm or more in the raw material powder can be confirmed by the heat treatment. The formation of coarse particles and the presence or absence of powder can be visually confirmed. Generally, when such coarse particles are formed by heat treatment, the α-diketone compound adheres to the surface of the coarse particles by sublimation-coagulation of the α-diketone compound. Due to such sublimation-coagulation, the α-diketone compound powder (particles) present at the time of preparation of the raw material powder disappears, and its presence cannot be visually confirmed. From the viewpoint of performing the heat treatment step more reliably, it is preferable to confirm disappearance of the α-diketone compound powder (particles) by observing a small amount of the sample with an optical microscope. In addition, the α-diketone compound can be easily detected visually and with an optical microscope (because the α-diketone compound has a color tone such as yellowish green to yellow to brown in relation to being excited by the wavelength of visible light). can be confirmed.

The heat treatment time in the aggregation step varies depending on the heat treatment temperature and the blending amount of the α-diketone compound, but is usually about 8 hours to 10 days.

(3) Pulverization step In the pulverization step, the coarsely aggregated particles obtained in the above step are pulverized. The pulverization is usually performed after cooling the heat-treated raw material powder to about room temperature. There are no particular restrictions on the method of pulverizing the coarsely aggregated particles. For example, devices such as roll grinding, ball milling, blade stirring, hammer mills, and jet mills may be used. By shaking and mixing, the aggregated powder material may collide with the wall surface and be pulverized, or may be transferred into a bag and kneaded.

However, when a strong shearing force is applied for a long time, such as when using high-speed impeller stirring, the (primary) particles that make up the amorphous resin powder are deformed. Care should be taken because the timing of paste fluidity and viscosity increase may change in the application of the denture base relining material. Therefore, in the case of mechanical pulverization using a pulverizer, it is preferable to confirm conditions, pulverization efficiency, particle deformation, and the like in advance.

In pulverization (crushing), it is not possible to pulverize all coarsely aggregated particles into primary particles, and the powder composition obtained after pulverization contains aggregated particles. The degree of pulverization (cracking) may be appropriately determined depending on the application. However, in the case of a powder material for a denture base relining material, from the viewpoint of not impairing the viscosity increase performance of the paste in the application, the powder can be obtained after pulverization. It is preferable to pulverize so that the maximum diameter of the aggregated particles obtained is 0.3 mm or less. The maximum diameter of the agglomerated particles was determined by placing 0.1 g of agglomerated particles obtained after pulverization on a transparent resin film, gently spreading it to 5 cm square so as not to break up the agglomerates, and examining an optical film with a micrometer at a magnification of 100 times. It can be confirmed by observation with a microscope or the like. In addition, if classification using a sieve is performed, the composition may differ from that of the raw material powder. Therefore, if coarse particles are present, the output of the device should be increased or the treatment time should be increased without performing classification. It is preferable to pulverize (pulverize) the entire amount until the desired particle size is obtained.

In addition, in the pulverization step, the α-diketone compound, which does not adhere to the surface of the coarsely aggregated particles due to sublimation-coagulation in the agglomeration step, adheres to the surface of the pulverized particles. However, this also makes it possible to obtain the effect of preventing reaggregation.

2. Relining material manufacturing method of the present invention The powder composition obtained by the composition manufacturing method of the present invention can be used for various applications such as instant polymerized resins and dental adhesives. It can be particularly suitably used as a powder material for. That is, a photopolymerization type denture base relining material comprising a liquid material containing a polymerizable monomer and a tertiary amine compound, and a powder material containing a powder composition containing resin particles and an α-diketone compound. According to the method for producing a lining material of the present invention, wherein the powder composition constituting the powder material is produced by the composition production method of the present invention, the powder material during storage It is possible to manufacture a denture base relining material that prevents the agglomeration of the denture base material, and has an appropriate paste fluidity during use and a stable viscosity increase timing for a long period of time.

The method for producing the liquid material in the method for producing the lining material of the present invention is not particularly different from the method for producing the liquid material in the conventional powder-liquid type lining material using a photopolymerization initiator. The tertiary amine compound and other optional ingredients may be weighed in the required amounts and mixed.

Polymerizable monomers include methyl (meth) acrylate, ethyl (meth) acrylate, hydroxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-(meth) acryloyloxyethyl propionate, acetoacetoxyethyl Monofunctional (meth)acrylic monomers such as (meth)acrylate; 1,6-bis((meth)acryloylethyloxycarbonylamino)trimethylhexane, 2,2-bis((meth)acryloyloxyphenyl)propane, ethylene glycol Bifunctional (meth)acrylic monomers such as di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate; trifunctional (meth)acrylic monomers such as methylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate; and the like. These (meth)acrylic monomers may be used alone or in combination of two or more. In particular, when a monofunctional (meth)acrylic monomer and a bifunctional or higher (meth)acrylic monomer are used together, the resulting cured product can have good mechanical properties such as strength and durability. preferable.

Tertiary amine compounds include methyl p-dimethylaminobenzoate, ethyl p-dimethylaminobenzoate, N,N-dimethylaniline, N,N-dibenzylaniline, N,N-dimethyl-p-toluidine, N , N-diethyl-p-toluidine, triethanolamine, N-methyldiethanolamine, 2-(dimethylamino)ethyl methacrylate and the like. The amount of the tertiary amine compound compounded is preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

Other ingredients include non-polymerizable acidic compounds such as malic acid, tartaric acid, and citric acid; perfumes such as essences, flavors, and refined oils. The blending amount of the other components is preferably 0.005 to 0.05 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

EXAMPLES Hereinafter, the present invention will be described with reference to examples in order to specifically describe the present invention, but the present invention is not limited by these examples.

First, the names, characteristics, abbreviations (when abbreviations are used), and evaluation methods of substances used in the preparation of raw material powders (powder materials) in each example and comparative example will be described.

(1) Amorphous resin powder PEMA35: Spherical polyethyl methacrylate particles (average particle diameter 35 µm, weight average molecular weight 500,000, Tg = 65°C)
・PEMA2: Spherical polyethyl methacrylate particles (average particle size 2 μm, weight average molecular weight 500,000, Tg=65° C.)
・PEMA5: Spherical polyethyl methacrylate particles (average particle size 5 μm, weight average molecular weight 500,000, Tg=65° C.)
・PEMA100: Spherical polyethyl methacrylate particles (average particle size 100 µm, weight average molecular weight 500,000, Tg = 65°C)
・PEMA200: Spherical polyethyl methacrylate particles (average particle size 200 μm, weight average molecular weight 500,000, Tg=65° C.)
・PEMA35A: Spherical polyethyl methacrylate particles (average particle size 35 μm, weight average molecular weight 50,000, Tg=65° C.)
・PEMA35B: Spherical polyethyl methacrylate particles (average particle size 35 μm, weight average molecular weight 200,000, Tg=65° C.)
・PEMA35C: Spherical polyethyl methacrylate particles (average particle size 35 μm, weight average molecular weight 1 million, Tg=65° C.)
- PEMA35D: spherical polyethyl methacrylate particles (average particle size 35 µm, weight average molecular weight 2 million, Tg = 65°C).

(2) α-diketone compound CQ: camphorquinone (melting point 203° C.)
- B: benzyl (melting point 96°C).

(3) Inorganic fine particles Silica fine particles: Rheolosil (average particle diameter 120 nm).

Example 1
100 parts by mass of PEMA35 as an amorphous resin powder and 0.3 parts by mass of CQ (average particle size: 100 to 200 μm) as an α-diketone compound, and a polypropylene with a volume of 100 ml that can be sealed with a screw lid After introducing into the resin bottle, the cap was closed and mixed with a rocking mixer to prepare raw material powder (raw material powder preparing step).

Then, the container was removed from the oscillating mixer and stored in a 55° C. thermostat (an incubator manufactured by Yamato Scientific Co., Ltd.) with the lid closed. After that, every day, the lid of the container is removed so as not to vibrate the container, and it is checked whether aggregates are generated in the powder material inside. If the thickness was 2 mm or less, it was determined that aggregation had not yet occurred, and the storage at 55° C. was continued in a hermetically sealed state. The heat treatment period (hour) was defined as the number of days (4 days in this example) when aggregates of 2 mm or more were first observed in the raw material powder, and the heat treatment was terminated. As is clear from such a determination method, the heat treatment period (days) corresponds to the aggregation period (hours) during storage of the raw material powder at 55°C.

When the raw material powder after the heat treatment was checked, it was visually confirmed again that a large number of coarse particles having a particle size of 2 mm or more were formed. A few coarse particles were sampled and observed with an optical microscope to find that the CQ particles had disappeared, suggesting that all the CQ particles adhered to the surface of the aggregates by sublimation and coagulation (aggregation step).

After that, the aggregated powder material was shaken in the container to crush coarse particles. Determination of crushing is carried out by taking out 0.1 g of the powder material inside the container on a transparent resin film, gently spreading it in a 5 cm square, and repeating it until the aggregated particles become 0.3 mm or less by microscopic observation with a micrometer. (grinding process).

A portion of the obtained powder composition (powder material) was used to evaluate reaggregation in the following manner. That is, in the evaluation of reaggregation, in the same manner as the determination of the heat treatment period described above, the powder composition is sealed in a container and heated and stored again in a thermostat at 55 ° C., and the powder is checked every day. The reaggregation period was defined as the number of days until aggregates of 2 mm or more were formed in the material. As a result, the number of days required for reaggregation was 22 days, which was 18 days longer than when the raw material powder was stored as it was.

In addition, in order to confirm the effect on the paste properties and curing properties of the paste (obtained by mixing the powder material and the liquid material) when used as a photopolymerization type powder-liquid denture base lining material, the above-mentioned Paste 1 using the powder material and liquid material obtained by performing the agglomeration process and the pulverization process, and raw material powder without performing these processes (raw material powder prepared in the same manner as above, within three days after preparation Consistency and cure depth were measured for Paste 2 using the material) and the results were compared. At this time, as the liquid material, a mixture of 50 parts by mass of 2-methacryloxyethylpropionate and 50 parts by mass of 1,9-nonamethylenediol dimethacrylate is added to a polymerizable monomer as a tertiary amine compound. 0.5 parts by mass of ethyl p-dimethylaminobenzoate and 0.01 parts by mass of malic acid as other components were added and stirred to prepare a mixture. The methods and results for measuring consistency and cure depth are shown below.

<Consistency>
Measurement method: 1.8 g (180 parts by mass) of the powder material and 1.0 g (100 parts by mass) of the liquid material are placed in a rubber cup and mixed for 20 seconds. was filled with a photocurable composition obtained by mixing After 1 minute and 30 seconds from the start of mixing, 0.5 mL of the paste was discharged onto a polypropylene film, and after 2 minutes from the start of mixing, a weight of 7.355 N was applied for 5 minutes via another polypropylene film. Then, the diameter of the expanded paste was measured at 4 points, and the average value was taken as the consistency.
Results: Consistency 1 of paste 1 was 45 mm, consistency 2 of paste 2 was 47 mm, and no significant difference was observed between the two.

<Light curing depth>
Measurement method: 1.8 g (180 parts by mass) of the powder material and 1.0 g (100 parts by mass) of the liquid material were placed in a rubber cup and mixed for 20 seconds. A cylindrical black rubber tube having an inner diameter of 4 mmφ, an outer diameter of 6 mmφ, and a height of 10 mm was filled with a kneaded paste (a photocurable composition obtained by mixing a powder material and a liquid material), and both sides were pressed with polypropylene films. . After that, from one end of the cylindrical black rubber tube filled with the paste, actinic light with a wavelength of 465 to 475 nm (optical power density: 100 mW/cm ² ) was applied using a dental laboratory photopolymerization device α Light V (manufactured by MORITA). Irradiated for 5 minutes to produce a cured product. The sample was removed from the black rubber tube, the uncured portion was removed, and the length of the cured portion was measured with a vernier caliper to determine the photocuring depth.
Results: Photocuring depth 1 of paste 1 was 4.4 mm, and photocuring depth 2 of paste 2 was 4.4 mm, and no significant difference was observed between the two.

Comparative example 1
A paste is prepared in the same manner as in Example 1, except that raw material powder preparation and agglomeration treatment are performed in the same manner as in Example 1, and the material obtained by the agglomeration treatment is used as the powder material without performing the pulverization step. Property evaluation and cured body property evaluation were performed. As a result, the consistency was 66 mm and the photocuring depth was 3.8 mm, which were significantly different from the values of Paste 2 (the consistency was longer and the photocuring depth was shallower).

Comparative example 2
Raw material powder was prepared in the same manner as in Example 1, and the agglomeration process was performed in the same manner as in Example 1 except that the temperature of the constant temperature bath was 25 ° C. It took 70 days until aggregates of 2 mm or more were formed. I needed it.

Comparative example 3
Raw material powder was prepared in the same manner as in Example 1, and left in a constant temperature bath at 70° C. for one day. As a result, the raw material powder was strongly agglomerated in the container, and the pulverization process could not be performed by the same method.

Examples 2-9
Evaluation was carried out in the same manner as in Example 1 except that the α-diketone compound used was changed as shown in Table 1, and the heat treatment temperature and time in the aggregation step were also changed as shown in Table 1.

Table 1 also shows the period required for reaggregation. In addition, the heat treatment period (hour) in Table 1 means the day when aggregates of 2 mm or more were confirmed for the first time as in Example 1, and the heat treatment was discontinued on that day. If the number of days up to is longer than that, reaggregation is suppressed. As in Example 1, there was no significant difference in consistency and hardening depth.

Example 2 is an example in which the heat treatment temperature is lowered to 45° C., and the number of treatment days is prolonged, but within the allowable range. Examples 3 to 5 are examples in which the average particle size of the CQ used was changed, and the larger the average particle size, the longer the minimum required number of heat treatment days. Examples 6 to 8 are examples in which the blending amount of CQ was changed, and there is a tendency that the greater the blending amount, the shorter the minimum number of required heat treatment days. Example 9 is an example using B instead of CQ, and similar effects were confirmed.

Examples 10-17
Evaluation was performed in the same manner as in Example 1, except that the amorphous resin powder used was changed as shown in Table 2, and the heat treatment temperature and time in the agglomeration step were also changed as shown in Table 2.

Table 2 also shows the period required for reaggregation. As in Example 1, there was no significant difference in consistency and hardening depth.

Among the examples shown in Table 2, Examples 1 and 10 to 13 are obtained by changing the average particle size of the PEMA powder, which is an amorphous resin powder. From these results, the average particle size of the amorphous resin powder does not greatly affect the effect, but in Example 11 using PEMA with an average particle size of 2 μm, Example 1 using PEMA with an average particle size of 35 μm In addition, the number of days until re-aggregation was shorter than in Example 1. It is considered that these are because the contact points between the particles increased due to the decrease in the average particle size of the resin particles, and the aggregation became stronger.

Furthermore, in Examples 1 and 14 to 17, the weight-average molecular weight of PEMA, which has the same average particle size, was changed. From these results, it can be seen that the weight-average molecular weight does not significantly affect the effect. . In addition, in Example 17 using one having a weight-average molecular weight of 2,000,000, it was more difficult to disaggregate than in Example 1. It is considered that this is because the polymer molecular weight of the resin particles is large and the entanglement of the polymer molecular chains between the resin particles is increased.

Examples 18-20
A raw material powder was prepared in the same manner as in Example 1, except that 100 parts by mass of PEMA35 and 0.3 parts by mass of CQ (having an average particle size of 100 to 200 μm) were mixed with fine silica particles. The amount of the silica fine particles to be blended was 0.15 parts by mass in Example 18, 0.03 parts by mass in Example 19, and 0.3 parts by mass in Example 20. Powder materials were prepared and evaluated in the same manner as in Example 1 using each of the obtained raw material powders. As a result, in Examples 18 and 20, reaggregation did not occur even after 50 days or more, and in Example 19, the number of days required until reaggregation was 29 days. Table 3 shows the results. No significant difference was observed in the paste state and the properties of the cured product in any of the examples. In addition, in any of the examples, in the pulverization step, the aggregates could be crushed more easily than in the pulverization step of Example 1.

Claims (6)

Raw material powder preparation step of preparing raw material powder containing amorphous resin powder: 100 parts by mass and α-diketone compound powder: 0.05 to 1.0 parts by mass;
The raw material powder is treated at a heat treatment temperature of 40° C. or higher and lower than the glass transition point of the amorphous resin to obtain coarsely aggregated particles in which the amorphous resin constituting the amorphous resin powder is aggregated. an agglomeration step of obtaining coarsely aggregated particles having an α-diketone compound present on the surface; and a pulverizing step of pulverizing the coarsely agglomerated particles;
including
obtaining a powder composition containing aggregated particles that are pulverized coarsely aggregated particles;
A method for producing a powder composition characterized by: The raw material powder is an amorphous resin powder having an average particle size (50% volume average particle size) of 1 to 300 μm measured by a laser diffraction method, and an average particle size (50% number of particles) measured by a laser diffraction method. The method for producing a powder composition according to claim 1, comprising an α-diketone compound powder having an average particle diameter) in the range of 50 to 300 μm. The raw material powder is inorganic fine particles having an average particle size (50% volume average particle size) of 0.01 to 0.2 μm measured by a laser diffraction method, and amorphous resin powder: 100 parts by mass The method for producing a powder composition according to claim 1 or 2, comprising 0.03 to 0.3 parts by mass. The method for producing a powder composition according to any one of claims 1 to 3, wherein in the agglomeration step, the raw material powder is allowed to stand under normal pressure and the heat treatment temperature to obtain coarsely agglomerated particles. . The powder according to any one of claims 1 to 4, wherein in the pulverization step, the coarsely aggregated particles are pulverized so that the maximum particle size of the aggregated particles measured with an optical microscope is 0.3 mm or less. A method of making a body composition. Manufacture of a photopolymerization type denture base relining material comprising a liquid material containing a polymerizable monomer and a tertiary amine compound and a powder material comprising a powder composition containing resin particles and an α-diketone compound. a method for
A method for producing the denture base relining material, wherein the powder composition constituting the powder material is produced by the production method according to any one of claims 1 to 5.