JPH11310508A - Dental resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dental resin composition which is improved in discoloration and coloration caused by its long term application in the oral cavity or discoloration and coloration due to heating and also possesses excellent impact resistance, handling and preservative stability. SOLUTION: This dental resin composition includes (a) an impact resistant resin composite which is composed of a core shell type resin particle having at least one of hard layer, at least one of soft layer and the most outer hard layer and a (metha)acrylic polymer and contains an ionic component less than 0.05 wt.%, (b) a (metha)acrylic ester-based monomer and (c) a polymerization initiator. In this case, the impact resistant resin composite is contained in a proportion of 5-80 wt.% based on the dental resin composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dental resin composition. More specifically, the present invention relates to a composition suitable for a denture base, a denture base rebase material, an orthodontic base, a denture repair material, a mouthpiece, a temporary crown, and the like.

[0002]

2. Description of the Related Art In a conventional dental treatment, for example, a prosthesis such as a denture base and an orthodontic base, and a mounting article used for orthodontics are sometimes made of a dental resin. When such a mounting article is manufactured, a method of mixing a powder containing polymethyl methacrylate as a main component and a liquid containing methyl methacrylate as a main component and polymerizing and curing the mixture is exclusively used. However, according to this method, one must wait until the mixed composition has developed a plasticity suitable for filling into the gypsum mold. Moreover, since the viscosity of the composition continues to increase with time, there is a problem that after a certain period of time, the composition becomes too hard to be used and the usable time is limited. In addition, there is a problem that bubbles are mixed into the composition when the powder and the liquid are mixed, and the strength and impact resistance of the polymer cured product are reduced.

[0003] To improve the impact resistance of a polymerized cured product, a dental resin composition in which an elastomer powder is mixed with a dental resin has been proposed (Japanese Patent Application Laid-Open No. 1-275509). However, the above composition has a non-uniform dispersibility of the elastomer powder in the polymer composition, and thus has insufficient impact resistance. Further, since the elastomer powder is a pulverized product and has an irregular shape, there is a problem that the affinity with the dental resin is not sufficient at the time of mixing the powder and liquid, and the operability is poor. Further, there is a problem that the discoloration becomes large when worn in the oral cavity for a long period of time due to the blending of the elastomer component, and the aesthetics of the polymer cured product are reduced.

Further, a dental composition comprising a rubber graft polymer, a (meth) acrylate compound and a polymerization initiator has been proposed (JP-A-3-63205). However, this rubber graft polymer is (meth)
Although there is some compatibility with the acrylate compound, the two components are mixed by a simple blend, so that the rubber graft polymer particles remain aggregated and the dispersibility in the composition becomes uneven. For this reason, dental or denture base compositions do not have sufficient impact resistance. In addition, there is a problem that the discoloration resistance is not improved and the aesthetics are reduced.

To improve the dispersibility of the rubber graft polymer, a denture base comprising spherical particles of a methyl methacrylate polymer containing a rubber graft polymer therein, a (meth) acrylate compound and a polymerization initiator has been proposed. A composition has been proposed (JP-A-6-57157). Although the dispersibility of the spherical particles in the composition is improved, the addition of a suspension dispersion stabilizer or the like during the production of the particles causes discoloration due to hot water or the like and a decrease in strength due to water absorption. Was. Further, methyl methacrylate-based polymer particles having a surface layer coated with a rubber graft polymer, (meth)
A denture base composition comprising an acrylate compound and an organic peroxide has been proposed (JP-A-6-2478).
No. 24). The methyl methacrylate polymer particles show improvement in dispersibility in the composition. However, since a coagulant is used in the production of these particles, there is a problem in that the aesthetics of the denture base is reduced due to discoloration due to heat or the like, and a problem in that the strength is reduced due to water absorption.

[0006] By improving the dispersibility of the rubber graft polymer in the composition, the impact resistance of dental resins and denture base resins has been improved. However, since these rubber graft polymers contain a large amount of stabilizers, coagulants, and the like used in the production process, the dental resin containing this material has a reduced strength due to water absorption due to long-term wearing in the oral cavity, and has a hydrophilic property. There is a problem that discoloration occurs due to a sex dye or hot water.

Further, a polymerizable composition comprising a polyfunctional crosslinkable composition, a crosslinked polymer and a rubber-modified polymer has been proposed as having excellent impact resistance and handleability (Japanese Patent Application Laid-Open No. 7-286018). However, this polymerizable composition contains a crosslinked polymer as an essential component in order to improve handling properties, and the improvement in impact resistance is insufficient. Further, no improvement has been observed in the discoloration of the composition.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dental resin composition which solves the above problems and has excellent impact resistance and resistance to discoloration.

[0009]

That is, the present invention provides:
(A) Core-shell type resin particles having at least one or more hard layers, at least one or more soft layers and outermost hard layers, and a (meth) acrylic polymer, and 0.05% by weight or less of an ionic component An impact-resistant resin composite containing
(B) (meth) acrylate monomer and (c)
It is a dental resin composition containing a polymerization initiator.

[0010] The impact-resistant resin composite compounded in the dental resin composition of the present invention is a fine particle of sea-island structure comprising core-shell type resin particles and a (meth) acrylic polymer, or a core-shell type resin. It is a particle aggregate of particles and (meth) acrylic polymer particles. The composition containing the sea-island-type fine particles or the particle aggregate has a higher core-shell type resin particle size than the composition containing a mixture of the core / shell type resin particle and the (meth) acrylic polymer particle. It has excellent dispersibility and has the advantage that the mixed state can be made more uniform. This is considered to be one reason for improving the impact resistance of the polymer cured product obtained from the composition of the present invention.

The islands-in-the-sea structure fine particles of the core-shell type resin particles and the (meth) acrylic polymer can be copolymerized with the core-shell type resin particles, the (meth) acrylic ester type monomer, and these. It is produced by polymerizing other monomers, and has a structure in which a (meth) acrylic polymer is used as a sea component and core / shell type resin particles are dispersed as an island component. A part of the core-shell type resin particles may be aggregated by itself. The shape of the sea-island structure fine particles of the core-shell type resin particles and the (meth) acrylic polymer is not particularly limited, but the average particle size is 20 to 2000 μm from the viewpoint of handleability when obtaining the composition.
It is preferred that

[0012] The particle aggregate of the core-shell type resin particles and the (meth) acrylic polymer particles used in the dental resin composition of the present invention is prepared by mixing the suspension of the core-shell type resin particles with the (meth) ) A method of mixing with a suspension of acrylic polymer particles, or a method of mixing a suspension of core-shell type resin particles with (meth)
It is produced by a method of adding and mixing acrylic polymer particles, and is a particle aggregate of a plurality of core-shell type resin particles and a plurality of (meth) acrylic polymer particles. This particle aggregate is obtained by randomly or alternately aggregating core-shell type resin particles and (meth) acrylic polymer, and so that (meth) acrylic type polymer particles cover core / shell type resin particles. Aggregated or (meth) acrylic polymer particles are aggregated so as to be covered with core / shell type resin particles.

The core-shell type resin in the dental resin composition of the present invention comprises at least one hard layer and at least one hard layer.
It comprises the above soft layer and has an outermost hard layer. The definition of the hard resin and the soft resin in the present invention is, in consideration of use in the oral cavity, a range of 30 ± 10 ° C., a resin having a Tg of 40 ° C. or more as a hard resin, and a Tg of less than 20 ° C. Is a soft resin. Preferably Tg
Is a resin having a temperature of 50 ° C. or higher as a hard resin, and a resin having a Tg of less than 0 ° C. as a soft resin.

[0014] The hard layer is made of a resin of 40 ° C.
It has a Tg of 50 ° C. or higher. The soft layer is formed of a soft resin itself of less than 20 ° C., preferably 0 ° C.
It has a Tg of less than. Each of these resins contains at least one (meth) acrylate 40-40% by weight,
0-60% by weight of other monomer units copolymerizable therewith,
In the range of 0 to 5% by weight of the polyfunctional monomer unit, the desired T
g.

The following units are used as the monomer units constituting the hard layer and the soft layer of the core-shell type resin. Examples of the (meth) acrylate include methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, pentyl methacrylate, and cyclohexyl methacrylate. Also, methyl acrylate, ethyl acrylate, butyl acrylate,
Examples include acrylates such as 2-ethylhexyl acrylate, cyclohexyl acrylate, and benzyl acrylate. These (meth) acrylates are used alone or in combination.

As other copolymerizable monomers, 1,3-
Butadiene, 2,3-dimethylbutadiene, diene compounds such as isoprene, styrene, vinyltoluene, α-
Aromatic vinyl compounds such as methylstyrene, N-cyclohexylmaleimide, N-O-chlorophenylmaleimide, N-substituted maleimides such as N-tert-butylmaleimide, acrylonitrile, vinyl cyanide compounds such as methacrylonitrile, and the like. Are used alone or in combination.

Further, as the polyfunctional monomer, allyl methacrylate, allyl acrylate, triallyl cyanurate,
Allyl cinnamate, allyl sorbate, diallyl maleate, diallyl phthalate, triallyl trimetate, diallyl fumarate, ethylene glycol (meth) acrylate, polyethylene glycol di (meth) acrylate,
Examples include polyfunctional monomers such as divinylbenzene and 1,3-butylene glycol di (meth) acrylate, which are used alone or in combination.

The outermost layer of the core-shell type resin particles is preferably a hard layer in order to obtain good dispersibility when mixed with a (meth) acrylate monomer. The ratio of the outermost hard layer is not particularly limited, but is preferably from 10 to 80% by weight based on the entire core-shell type resin particles.

The core-shell type resin particles can have an arbitrary multilayer structure. For example, in the core-shell type resin including the outermost layer, the innermost layer includes a soft layer-hard layer two-layer structure, a hard layer-soft layer-hard layer three-layer structure, and a soft layer-hard layer-soft layer-hard layer. Such a structure as a four-layer structure of a layer, a four-layer structure of a hard layer, a soft layer, a soft layer, and a hard layer is employed.

The polymerization method of the core-shell type resin of the present invention is not particularly limited, but a generally known emulsion polymerization method is preferred. The particle of the core-shell type resin is not particularly limited, but may have a particle size range of 0.01 to 0.5 μm. The thickness is preferably 0.05 to 0.3 μm for the development of impact resistance.

(Meth) used in the resin composite of the present invention
The acrylic polymer particles are hard polymers composed of 50 to 100% by weight of at least one (meth) acrylate unit and 0 to 50% by weight of other monomer units copolymerizable therewith. The (meth) acrylate and other copolymerizable monomer units constituting the (meth) acrylic polymer particles have a Tg of (meth) acrylic polymer of 4
Any of the monomers that can be used for the hard resin of the core-shell type resin can be used arbitrarily so that the temperature is 0 ° C. or higher, preferably 50 ° C. or higher. The average particle size of the (meth) acrylic polymer particles is 20-200.
It is preferable that the thickness is 0 μm because the composition is excellent in handleability when obtaining the composition.

An impact-resistant resin composite containing a core-shell type resin, a (meth) acrylate monomer,
A dental resin composition containing a polymerization initiator gives a cured product having excellent impact resistance. However, when the dental hardened material is used in the oral cavity for a long period of time, there has been a problem of a decrease in impact resistance and discoloration. The present inventors have conducted intensive studies in view of such a situation, and as a result, surprisingly, that the ion content in the impact-resistant resin composite greatly affects the durability of the dental resin composition in the oral cavity. I found it. That is, when the ion content in the impact-resistant resin composite containing the core-shell type resin is 0.05% by weight or more, the polymerized cured product of the dental resin composition becomes more colored with edible dyes.
Further, when the cured product is exposed to hot water, cloudiness of the cured product is increased, and the aesthetics are significantly reduced. This clouding does not disappear once it occurs, greatly impairing the transparency of the cured product. Further, the strength of the polymerized cured product is reduced by water absorption, and the impact resistance cannot be maintained for a long time. As the ionic component, sodium, alkali metal ions such as potassium, magnesium,
Examples thereof include alkaline earth metal ions such as aluminum.

The resin composite produced by the above method can be easily obtained by a method of adding a coagulant to a reaction product, ie, a suspension, to coagulate, or a method of directly spray-drying the suspension. Further, the suspension can be freeze-coagulated to separate the resin complex. According to studies by the present inventors, the resin composite obtained by the coagulant addition method and the resin composite obtained by the spray drying method have a high content of ionic components, and the ion content of the resin composite obtained by the freeze coagulation method is high. The amount was found to be low enough.

The method of reducing the content of the ionic component in the impact-resistant resin composite containing the core-shell type resin to 0.05% by weight or less comprises separating the composite from the suspension containing the composite. Is a method of separating by freeze coagulation. In the freeze coagulation method, the composite particles are aggregated by physical cohesion without using a coagulant, which is an ionic component, by freezing a suspension containing the composite. Further, at this time, the emulsifier used in the polymerization moves into water and is removed from the composite. By separating the freeze-coagulated particles from the suspension, melting and dewatering, resin composite particles having an ionic component content of 0.05% by weight or less can be easily obtained.

The impact-resistant resin composite containing the core-shell type resin is obtained by adding a coagulant to separate the resin composite particles, or by separating the resin composite having a large amount of ionic components by a spray drying method or the like. When the resin composite is a product, the ionic component is removed from the resin composite by at least one method of washing with warm water, ion exchange, and precipitation by adding an acid, and the amount of the ionic component in the resin composite is reduced to 0.05% by weight. It is necessary to adjust the following.

Examples of the coagulant used in the step of separating the composite from the suspension include sulfates such as magnesium sulfate and sodium sulfate, and chlorides and acetates.

As the (b) component (meth) acrylate monomer used in the dental resin composition of the present invention, monofunctional (meth) acrylates and polyfunctional (meth) acrylates can be used. ) Any of the acrylates can be used.

As the monofunctional (meth) acrylic acid ester, for example, alkyl (meth) acrylate (alkyl group having 1 to 25 carbon atoms) and other (meth) acrylates can be used. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, myristyl (meth) acrylate and stearyl (meth) acrylate Alkyl (meth) acrylates such as acrylates (alkyl groups having 1 to 25 carbon atoms), methoxyethyl (meth) acrylate, 2-phenoxyethyl (meth)
Acrylate, methoxypolyethylene glycol (meth) acrylate (degree of polymerization 2 to 10), tetrahydrofurfuryl (meth) acrylate, isobornyl (meth)
Examples include acrylate, undecenyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate (HEMA), and dimethylaminoethyl (meth) acrylate.

Examples of the polyfunctional (meth) acrylate include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate,
Neopentyl glycol di (meth) acrylate, 1,
Alkylene glycol di (meth) acrylates (1 to 20 carbon atoms in the alkylene group), such as 6-hexanediol di (meth) acrylate and 1,10-decanediol di (meth) acrylate; diethylene glycol di (meth) acrylate; Polyalkylene glycol di (meth) acrylates having 2 to 2 carbon atoms such as ethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate and polyethylene glycol di (meth) acrylate
4, and a degree of polymerization of 2 to 200), glycerin di (meth) acrylate, 2,2′-bis [p- (γ-methacryloxy-β-hydroxypropoxy) phenyl] propane (Bis-GMA), bisphenol A Dimethacrylate, 2,2′-di (4-methacryloxypolyethoxyphenyl) propane (an ethoxy group having 2 to 1
0), 1,2-bis (3-methacryloxy-2-hydroxypropoxy) butane, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, urethane (meth) acrylate and the like. These (meth) acrylate monomers are used alone or in combination of two or more.

Examples of the polymerization initiator include a photopolymerization initiator, a thermal polymerization initiator, and a room temperature polymerization initiator.

Examples of the photopolymerization initiator include α-diketones such as camphorquinone, diacetyl, 2,3-pentanedione, benzyl, acenaphthenequinone and phenanthraquinone, and 2,4,6-trimethylbenzoyldiphenylphosphine. Acyl phosphine oxides such as oxide, benzoin methyl ether, benzyl dimethyl ketal, benzophenone, 2-ethylthioxanthone and the like.

These photopolymerization initiators include tertiary amines,
It is used as a photopolymerization initiator-based catalyst appropriately combined with a reducing agent such as aldehyde and mercaptan.

Such tertiary amines include, for example,
N, N-dimethylaminoethyl methacrylate, N, N
-Ethyl-dimethylaminobenzoate, bis-N, N-dimethylaminobenzophenone, N, N-dimethylaminobenzaldehyde, N-phenylglycine, morpholinomethacrylate, triethanolamine, N-methyldiethanolamine, N, N-dimethylaminobenzoic acid 2-
Examples thereof include n-butoxyethyl and isoamyl N-dimethylaminobenzoate.

Examples of the aldehyde include citronellal, lauryl aldehyde, o-phthaldialdehyde,
p-octyloxybenzaldehyde and the like can be mentioned.

Examples of the mercaptan include 1-decanethiol, thiosalicylic acid, 2-mercaptobenzoxazole, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 4-mercaptoacetophenone, 4-t-butylthiophenol and the like. Can be mentioned.

Further, a system in which an organic peroxide such as benzoyl peroxide is added to the photopolymerization initiator is also preferably used.

Examples of the thermal polymerization initiator include peroxides such as benzoyl peroxide, di-t-butyl peroxide and cumene hydroperoxide, azo compounds such as azobisisobutyronitrile, and teramethylthiuram disulfide. An initiator such as is used.

Further, as the room temperature polymerization initiator, redox initiators such as organic peroxide / aromatic tertiary amine type and organic peroxide / aromatic tertiary amine / aromatic sulfinic acid type are used. You.

When a combination of an oxidizing agent and a reducing agent is contained as a polymerization initiator, from the viewpoint of storage stability,
It is necessary to form a separate package so that these do not mix, and to mix them immediately before use.

The compounding amount of the impact-resistant resin composite in the dental resin composition of the present invention is 5 to 80% by weight of the whole.
If it is less than 5% by weight, the impact resistance becomes insufficient, and 80% by weight
Above, the discoloration resistance decreases. The amount of the (meth) acrylic ester monomer and the polymerization initiator is not particularly limited, but the amount of the (meth) acrylic ester monomer is 10 to 80 with respect to the entire composition. % By weight, and the polymerization initiator is desirably 0.05 to 5% by weight.

The dental resin composition of the present invention may contain, if necessary, a known organic filler (for example, polymethyl methacrylate), an inorganic filler (for example, silica powder), an organic composite filler, a fibrous reinforcing material, and the like. It can be added to improve the hardness and abrasion resistance after polymerization. Further, a polymerization inhibitor (for example, hydroquinone, hydroquinone monomethyl ether, butylhydroxyl toluene, etc.),
Oxidation stabilizers, UV absorbers (such as benzophenone, etc.), pigments, dyes and fibers for mimetic blood vessels can also be added.

[0042]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In this example, various tests were performed by the following methods.

(1) Impact Resistance Test of Polymerized and Cured Product Evaluated by a fracture toughness test. Literature [Matsumoto, “Dental Materials and Instruments”, Vol. 7, No. 5, pp. 756-768 (1988)
Year)]. That is,
The paste-like composition was filled into a mold having a prism shape of 2.5 × 5 × 30 mm and having a notch of 2.5 mm with a razor in the center, and the paste was covered with a glass plate. The paste was cured by heating in water for 1 hour. Using the obtained cured product as a test piece, the initial value and the value after the hot water treatment were measured. The initial value is 1 hour in water at 37 ° C.
After immersion in water, after hot water treatment, after immersion in water at 37 ° C. for 1 day, and further immersion in water at 100 ° C. for 1 hour, a crosshead speed of 1 mm / cm. min. A fracture toughness test was conducted at a distance between the fulcrums of 20 mm.

(2) Coloring test for food dyes [Tataka, "Prosthodontics" Vol. 35, No. 3, No. 542
555 (1991)]. That is, the paste composition is 1 mm thick,
The paste was filled in a disk-shaped mold having a diameter of 2 cm and heated in hot water at 100 ° C. for 1 hour to cure the paste. Using the obtained cured product as a test piece, coffee (manufactured by Nescafé) at 37 ° C
Was immersed in a 2% by weight aqueous solution for 7 days, and the change in color tone before and after immersion was measured using a color difference meter (manufactured by Nippon Denshoku).

(3) Discoloration test for hot water A test piece was obtained in the same manner as in the above-mentioned coloring test for food. This was immersed in hot water at 100 ° C. for 1 hour, and the change in transparency before and after immersion was measured using a color difference meter (manufactured by Nippon Denshoku) to evaluate cloudiness.

Example 1 EB-S (manufactured by Kuraray; ionic component amount 0.0277), which is a particle aggregate of ER-450 (manufactured by Kuraray) which is a core-shell type resin particle and (meth) acrylic polymer particles % By weight; freeze-coagulated product), 35 g of methyl methacrylate (manufactured by Wako Pure Chemical Industries, hereinafter abbreviated as MMA), and 1.0 g of benzoyl peroxide (manufactured by NOF Corporation, hereinafter abbreviated as BPO). A composition was prepared. Table 1 shows the measurement results of the fracture toughness value and discoloration of the polymerized cured product. Examples and comparative examples shown below are shown in the same manner.

Example 2 65 g of a particle aggregate of ER-450 and (meth) acrylic polymer particles (ionic component amount: 0.0488% by weight; washed with hot water after spray drying), 35 g of MMA, and BPO A composition containing 1.0 g was prepared.

Example 3 Modifier A (sea-island type fine particles of ER-450 and (meth) acrylic polymer particles) (ionic component amount 0.045
3% by weight; a product washed with hot water after salting out; a composition containing 65 g of MMA and 35 g of BPO was prepared.

Example 4 45 g of EB-S and 15 of MB30X-20 (manufactured by Sekisui Plastics Co., Ltd.) as a crosslinked polymethyl methacrylate powder were used.
g, 40 g of MMA and 1.0 g of BPO were prepared. The crosslinked polymethyl methacrylate swells in the composition but does not dissolve, so that the viscosity of the composition is stable and can be provided in the form of a paste.

Example 5 50 g of EB-S, 5 g of polymethylmethacrylate powder 100B (manufactured by Sekisui Chemical Co., Ltd.), 45 g of triethylene glycol dimethacrylate (manufactured by Shin-Nakamura Chemical),
A composition containing 1.0 g of BPO was prepared. By blending a (meth) acrylic acid ester monomer that swells but does not dissolve the polymer component, the viscosity of the composition is stabilized, and the composition can be provided in a paste form.

Example 6 55 g of EB-S and Aerosil 380 which is a silica powder
A composition containing 5 g (manufactured by Nippon Aerosil), 40 g of MMA, and 1.0 g of BPO was prepared.

Comparative Example 1 65 g of particle aggregate (ionic component amount: 0.0711% by weight; salted-out product) of ER-450 and (meth) acrylic polymer particles, 35 g of MMA, and 1.0 g of BPO A composition was prepared.

Comparative Example 2 Particle aggregate of ER-450 and (meth) acrylic polymer particles (ionic component amount: 0.223% by weight; spray-dried product)
, 65 g of MMA, and 1.0 g of BPO were prepared.

Comparative Example 3 65 g of modifier A, 35 g of MMA, 1.0 g of BPO
A composition comprising was prepared.

Comparative Example 4 Commercially available core-shell type resin particles M203 (manufactured by Kaneka Chemical Co .; ion component amount: 0.0800% by weight): 65 g, MM
A composition containing 35 g of A and 1.0 g of BPO was prepared.

Comparative Example 5 A commercial resin for denture base, Akron NO. 5 (GC
Was mixed at room temperature for 25 minutes, and then a paste-like dough was charged into a mold and polymerized in 100 ° C. water for 1 hour.

Reference Example 1 Production Method of Modifier A Latex of ER-450 as core-shell type resin particles (polymer solid content 1 kg, slurry concentration 28%) 10
MMA1300 in which 100 g of BPO was dissolved in 00 g
Then, 10 kg of deionized water and 1000 g of a 5% aqueous magnesium carbonate solution as a suspending dispersant were added. This dispersion was heated at 80 ° C. for 8 hours to polymerize MMA. Thereafter, 16 g of magnesium sulfate was added to this solution, and stirring was further continued at 60 ° C. for 1 hour. After the particles were separated from this liquid by filtration, the particles were dried at 60 ° C. for 24 hours to obtain modifier A as white particles. These particles are PM
These are sea-island type fine particles in which ER-450, which is a core-shell type resin particle, is dispersed in a matrix of MA.

[0058]

[Table 1]

[0059]

The dental resin composition according to the present invention comprises an impact-resistant resin comprising core-shell type resin particles and a (meth) acrylic polymer and containing not more than 0.05% by weight of an ionic component. Since the composite is blended, there is no reduction in strength due to water absorption even when worn in the oral cavity for a long time. In addition, it is possible to provide a highly aesthetic dental resin which is less liable to be colored by edible pigments or clouded by hot water.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 33/06 C08L 33/06 51/00 51/00

Claims (6)

[Claims] (A) core-shell type resin particles having at least one or more hard layers, at least one or more soft layers and an outermost hard layer, and a (meth) acrylic polymer,
And an impact-resistant resin composite containing 0.05% by weight or less of an ionic component, (b) a (meth) acrylate monomer and (c) a polymerization initiator. Dental resin composition. 2. The impact-resistant resin composite according to claim 1, wherein the core / shell type resin particles are island components and the (meth) acrylic polymer is a sea component. Dental resin composition. 3. The dental resin composition according to claim 1, wherein the impact-resistant resin composite is a particle aggregate of a plurality of the core-shell type resin particles and a plurality of the (meth) acrylic polymer particles. Stuff. 4. The dental resin composition according to claim 1, wherein the impact-resistant resin composite is contained in an amount of 5 to 80% by weight based on the weight of the dental resin composition. 5. The resin composition according to claim 1, wherein the impact-resistant resin composite comprises a resin composite suspension containing fine particles or agglomerates.
The impact-resistant resin composite having an ionic component of 0.05% by weight or less, which is obtained by freezing and coagulating without using a coagulant and separating a resin composite.
The dental resin composition according to any one of the above. 6. The resin composition according to claim 1, wherein the impact-resistant resin composite is a resin composite suspension containing fine islands-in-sea structures or particle aggregates.
Add a coagulant to separate the resin complex, or spray dry the resin complex suspension to separate the resin complex, and then wash the resin complex with hot water washing, ion exchange and acid addition The impact-resistant resin composite according to any one of claims 1 to 4, wherein the impact-resistant resin composite is treated by at least one method to remove an ionic component and reduce the ionic component to 0.05% by weight or less. Dental resin composition.