JP2020090574A - Manufacturing method of polymerization curable composition - Google Patents

Abstract

To provide a method for manufacturing a polymerization curable composition having inorganic particle dispersibility, capable of surely providing a cured body which becomes a composite material by dispersing an inorganic particle in a resin matrix and capable of coloring a structure color with a constant color tone without depending on a change of an incidence angle of light.SOLUTION: When a polymerization curable composition is manufactured by mixing a polymerizable monomer which becomes a matrix resin, and an inorganic spherical particle which has a specific average primary particle diameter, is extremely narrow in a particle size distribution width, and has a larger refractive index than a cured body of the polymerizable monomer, a radical distribution function of the cured body is evaluated by conducting sampling properly during a mixing process, and mixing is conducted so that a distance between nearest particles is 1 time to 2 times of an average particle diameter and a minimum value between the distance between nearest particles and a distance between second nearest particles is 0.56 to 1.10 finally.SELECTED DRAWING: Figure 1

Description

The present invention is a composite material in which inorganic particles are dispersed in a resin matrix, the appearance color tone can be controlled without using dyes or pigments, and the polymerization curing gives a composite material with little fading or discoloration. The present invention relates to a method for producing a sexual composition. In particular, the present invention relates to a method for producing a polymerization-curable composition that can be suitably used as a dental filling/restoring material that can be simply restored with excellent aesthetics.

Dental composite resin (hereinafter also simply referred to as "CR") is a kind of material for repairing a tooth damaged by caries, fracture, etc., and is a polymerizable monomer and an inorganic filler. And a polymerization curable composition containing. Restoration (CR restoration) using a dental composite resin (CR) is rapidly spreading because it can reduce the amount of cutting of tooth material, can impart a color tone equivalent to that of natural teeth, and is easy to operate. Further, in recent years, it has been used not only for the restoration of the anterior tooth portion but also for the molar portion to which a high occlusal pressure is applied because of the improvement of the mechanical strength and the adhesive force with the tooth.

As described above, it is one of the excellent characteristics of CR restoration that the restoration with high aesthetics is possible, but in order to perform restoration with high aesthetics, the color of the tooth to be restored (tooth to be restored) ( It is necessary to determine the hue and color tone (this type of color determination is also referred to as “shade taking”), and select a CR that matches the determined color to perform restoration. In this case, although one color CR may be used for restoration, when performing high-quality aesthetic restoration that faithfully reproduces the color change due to the tooth part, a plurality of CRs of different colors are laminated. It may then be repaired.

CR restoration, including such aesthetic restoration, can be performed by using one or more CRs whose color tone is adjusted by adding pigment substances or dye substances in different types and compounding amounts. It is common. However, in CR in which the color tone is adjusted by using a pigment substance or a dye substance, these substances in the cured body of CR are discolored or discolored due to deterioration over time, which causes discoloration over time after restoration, The appearance of the part may not match the natural teeth.

On the other hand, as a technique for coloring without using a pigment substance or a dye substance, there is a technique for generating color by utilizing reflection, interference, scattering, transmission of light by fine particles in a medium. There is also known a technique of developing a desired color of a composite material in which inorganic particles are dispersed in the medium (see Patent Documents 1 and 2).

For example, in Patent Document 1, “a fine particle dispersion in which first fine particles having an average particle diameter in the range of 50 nm to 1 μm and a Cv value of the particle diameter of 10% or less are dispersed in a medium, A short-range order in which the array structure of the first fine particles in the dispersion is an amorphous structure and satisfies a specific condition defined by "in-plane radial distribution function: g(r)". The “fine particle dispersion having a structure” is a structure in which fine particles are stably maintained, can reflect light of a specific wavelength, and the peak wavelength of reflected light changes according to the change of the incident angle of light. It is disclosed that the fine particle dispersion is capable of sufficiently reducing the angle dependence.

In addition, Patent Document 2 describes, for example, "a polymerizable monomer component (A), a spherical filler (B) having an average particle diameter within a range of 230 nm to 1000 nm and a polymerization initiator (C), and 90% or more of the individual particles constituting the filler (B) are present within the range of 5% before and after the average particle diameter, and the refractive index n _{F of the} spherical filler (B) at 25° C. is the polymerizable single particle. A curable composition satisfying the condition that the polymer obtained by polymerizing the monomer component (A) is higher than the refractive index n _P at 25° C. of a polymer, and a “cured product having a thickness of 1 mm is formed” And the lightness (V) of the colorimetric value of the colored light under the black background measured by the Munsell color system under a black background is less than 5 and the saturation (C) is 0.05 or more. And a curable composition in which the lightness (V) of the colorimetric value of the colored light by the Munsell color system under the white background is 6 or more and the saturation (C) is less than 2." Further, in Patent Document 2, CR composed of the above curable composition is (1) a dye substance or a pigment substance is not used, and thus the problem of discoloration over time does not easily occur. It can be colored yellow to red, which is the same color as the dentin (depending on the average particle size of the filler), and (3) because the cured product has appropriate transparency, It is easy to harmonize, and one type of composite resin can restore the appearance of a wide range of colors to be restored to a tooth close to a natural tooth without complicated shade-taking and shade selection of the composite resin. It has been described that it has the following characteristics.

In addition, in Patent Document 2, when the average particle size of the spherical filler used is less than 100 nm, the structural color is unlikely to occur, and when the spherical filler having the same average particle size of 150 nm or more and less than 230 nm is used, it is blue. It is also described that the structural color of the system appears, but it is difficult to match the color tone of the dentin surface in the deep part of the repair cavity.

Patent No. 5274164 International Publication No. 2017/069274 Pamphlet

According to Patent Document 1, fine particles having a uniform particle size are dispersed so as to have an amorphous structure as a whole while having a specific short-range ordered structure, thereby changing the incident angle of light. It can be seen that a structural color having a constant color tone that is not generated can be developed. Further, in Patent Document 2, colored light due to interference in a cured product of the curable composition (or a CR made of the curable composition) is generated in a portion where constituent particles are relatively regularly accumulated. , It is explained that the colored light due to scattering is generated in the portion where the constituent particles are randomly dispersed, and even in this system, the long-range irregularity and the short-range regularity in the dispersed state of the spherical filler are described. It can be inferred that the balance is important in obtaining the above effect.

However, in the CR disclosed in Patent Document 2, as the spherical filler (B) that achieves the above-mentioned effect, an aggregate of inorganic spherical particles having a predetermined average primary particle diameter within the range of 230 to 1000 nm is used. In the number-based particle size distribution of the aggregate, 90% or more of the total number of particles are present within a range of 5% before and after the predetermined average primary particle diameter, and only one type of aggregate is used. It was unclear how the above effects would be affected when a plurality of such aggregates having different diameters were used. Further, it has been found that, although the frequency is extremely low, a desired effect may not be obtained depending on the conditions for preparing CR by kneading each component.

Therefore, the present invention provides a composite material such as a cured product of the curable composition disclosed in Patent Document 2, which is capable of exhibiting the above effects even when a plurality of spherical filler aggregates are used. An object of the present invention is to provide a method for producing a polymerization-curable composition that is surely given.

The inventors of the present invention have disclosed a method for defining a short-range ordered structure using “in-plane radial distribution function: g(r)” disclosed in Patent Document 1 as a method for quantifying the dispersed state of spherical particles. Utilizing it, the inventors conducted a thorough study on the case of using a plurality of spherical filler aggregates. As a result, in the system as disclosed in Patent Document 2, on the assumption that spherical particles are dispersed so as to have an amorphous structure as a whole, it is possible to specify a short-range ordered structure capable of obtaining the above effect. In addition, when a specific condition is satisfied, even if a plurality of spherical filler aggregates are used, a short-range ordered structure type that develops a structural color in each spherical filler aggregate is maintained, and it is caused by each aggregate. It has been confirmed that the structural colors that develop are colored, and that they are colored in the combined color tone as a whole. Furthermore, they have found that the desired cured product (composite material) can be reliably obtained by controlling so that the dispersed state can be realized at the stage of the polymerization-curable composition, and completed the present invention.

That is, the first aspect of the present invention comprises a polymerizable monomer (A), inorganic particles (B) satisfying the following conditions (i), (ii) and (iii), and a photopolymerization initiator (C). A method for producing a polymerization-curable composition, which comprises a component, and gives a cured product that develops a structural color having a predetermined color tone,
The method includes a mixing step of mixing the polymerizable monomer (A), the inorganic particles (B) and the photopolymerization initiator (C),
In the mixing step, the dispersion state of the inorganic particles (B) in the cured product obtained by curing the mixture obtained in the step may satisfy the following conditions (I) and (II). The mixing is performed by using the confirmed mixing conditions,
The method is characterized by the above.
[Conditions that the inorganic particles (B) must satisfy]
(I) It is composed of an aggregate of inorganic spherical particles having a predetermined average primary particle diameter within the range of 100 to 1000 nm, and the individual inorganic spherical particles constituting the aggregate are composed of substantially the same substance. At the same time, in the number-based particle size distribution of the aggregate, 90% or more of the total number of particles is present within a range of 5% before and after the predetermined average primary particle size, and one or more "spherical particle groups having the same particle size ( G roup of spherical P article having I dentical D iameter) " including the (G-PID).
(Ii) When the number of the one or more "spherical particle groups having the same particle size" is a, the "spherical particle groups having the same particle size" are respectively G-PID _m (however, in the order of decreasing average primary particle size). , M is 1 when a is 1, and is a natural number from 1 to a when a is 2 or more.), each G-PID _m when a is 2 or more individual or different particles together material constituting the average primary particle diameter of each G-PID _m when the are different from each 25nm or more from each other.
(Iii) a refractive index at 25 ° C. of the polymerizable monomer cured product of components (A) and _{n (MX),} the refractive index at 25 ° C. of the inorganic spherical particles constituting the respective G-PID _{m n ( G-PIDm)} , for any n _(G-PIDm) ,
n _(MX) <n _(G-PIDm)
The relationship is established.
[Conditions that the dispersed state must satisfy]
(I) The distance from the center of any inorganic spherical particles dispersed in the cured product of the mixture: r is divided by the average particle diameter of the entire inorganic spherical particles dispersed in the cured product of the mixture: r _0. A radial distribution function that represents the probability that another inorganic spherical particle exists at a point separated by a distance r from the center of the arbitrary inorganic spherical particle, where x is a dimensionless number (r/r ₀ ) standardized by In the radial distribution function graph showing the relationship between the r/r ₀ and the g(r) corresponding to r at that time with (r) as the y-axis, among the peaks appearing in the radial distribution function graph, The closest particle distance: r ₁ defined as r corresponding to the peak top of the peak closest to the origin is 1 or more times the average particle size of all inorganic spherical particles dispersed in the cured product of the mixture: r ₀ It is a value of 2 times or less.
(II) Of the peaks appearing in the radial distribution function graph, when r corresponding to the peak top of the second peak closest to the origin is set as the next adjacent particle distance: r ₂ , the closest particle distance: The minimum value of the radial distribution function: g(r) between r ₁ and the distance between adjacent particles: r ₂ is 0.56 or more and 1.10.

In the above method of the present invention, the radial distribution function: g(r) is determined based on a scanning electron microscope image in which an inner surface of the cured body is an observation plane, and the inorganic substance in the observation plane is determined. Average particle density of spherical particles: <ρ>, and the number of inorganic spherical particles existing in a region between a circle of distance r and a circle of distance r+dr from any inorganic spherical particle in the observation plane: dn, And the area of the region: da (where da=2πr·dr) based on the following formula (1):
g(r)={1/<ρ>}×{dn/da} (1)
It is preferably calculated by

Further, in the method of the present invention, it is preferable that the method of determining the mixing condition adopted in the mixing step is the method shown in the following (1) or (2).
(1) Separately in advance, a composition having the same or substantially the same composition as the polymerization-curable composition to be actually produced was used, the mixing conditions were changed plural times, and the mixture was mixed under each mixing condition. Mixing conditions satisfying the above conditions (I) and (II) are determined by examining the radial distribution function: g(r) in the cured product of the mixture obtained at this time, and the determined mixture is determined. A method that employs the same mixing conditions as the conditions.
(2) A part of the mixture obtained during and/or after the mixing step is sampled, and the dispersion state of the inorganic particles (B) in the cured product of the sampled mixture is the conditions (I) and ( A method of confirming whether or not II) is satisfied and continuing mixing until these conditions are satisfied.

The compounding amount of the spherical particle group having the same particle diameter: G-PID in the polymerization-curable composition is the total amount of all G-PID contained (that is, the total amount of inorganic spherical particles), and the polymerizable monomer (A ) It is preferably 10 parts by mass to 1500 parts by mass, and particularly preferably 100 parts by mass to 1500 parts by mass, relative to 100 parts by mass of the component. Further, from the viewpoint of ease of handling when the obtained composition before polymerization and curing is used as a dental material, particularly a dental filling/restoring material, a color tone and a contrast ratio of a cured product (composite material) obtained by curing, The polymerization-curable composition comprises inorganic particles (B) having an average primary particle size of less than 100 nm, and the average primary particle size is 25 nm or more smaller than the average primary particle size of the G-PID _1. It is preferable to further comprise a group of fine particles" (G-SFP). At this time, the compounding amount of the ultrafine particle group: G-SFP is 0.1 to 50 parts by mass, particularly 0.2 to 30 parts by mass, relative to 100 parts by mass of the polymerizable monomer (A) component. Preferably. Further, at least a part of each of the “spherical particle groups having the same particle size” (G-PID) is one kind of “the same particle size” because the short-range ordered structure can be easily obtained. Spherical particle group" (G-PID) and a resin having a refractive index at 25°C smaller than the refractive index of the spherical particles constituting the one kind of "spherical particle group having the same particle size" (G-PID). Therefore, it is preferable that the filler is contained as an organic-inorganic composite filler that does not include the “spherical particle group of the same particle size” (G-PID) other than the one kind of the spherical particle group of the same particle size (G-PID).

ADVANTAGE OF THE INVENTION According to this invention, according to the average primary particle diameter of G-PID to be used, the polymerization curable composition which gives the hardened body which develops the predetermined structural color which does not depend on the incident angle of light reliably and efficiently is manufactured. can do. Therefore, it is possible to efficiently produce a polymerization-curable composition that gives a cured product that reliably exhibits the same effects as the cured product disclosed in Patent Document 2. That is, since (1) no dye substance or pigment substance is used, the problem of discoloration with time hardly occurs, and (2) the cured product has a blue-based transparency (depending on the average particle size of the spherical filler used). It can be colored in a desired color tone within a wide color tone range from a certain color tone to a yellow to red color tone which is similar to ivory color, and (3) the cured product has appropriate transparency. Therefore, when used as a dental restorative material, it is easy to harmonize with the color of the tooth to be restored, and a wide range of colors can be obtained with one type of composite resin without complicated shade-taking and shade selection of the composite resin. It is possible to efficiently produce a polymerization-curable composition that gives a cured product that reliably exhibits the excellent effect of being able to restore the appearance of a tooth to be restored close to that of a natural tooth. And, this point is that when the ultrafine particle group" (G-SFP) is added for the purpose of adjusting the viscosity of the polymerization-curable composition or the contrast ratio of the cured product, or the color tone of the structural color developed in the cured product. The same applies to the polymerization-curable composition using a plurality of “spherical particle groups having the same particle size” (G-PID) for adjusting the above.

FIG. 6 is a flow chart of a method for manufacturing a composite material according to an embodiment of the present invention. This figure is a diagram showing a scanning electron microscope image (left diagram) of an observation plane in the composite material of Example 1 and coordinate data (right diagram) obtained from the image. This figure is a diagram showing a radial distribution function graph regarding g(r) calculated based on the parameters determined from the coordinate data of FIG. 2. This figure is a diagram showing a radial distribution function graph in the composite material of Example 2. This figure is a diagram showing a radial distribution function graph in the composite material of Example 3. This figure is a diagram showing a radial distribution function graph in the composite material of Example 4. This figure is a diagram showing a radial distribution function graph in the composite material of Comparative Example 1.

The method for producing a polymerization-curable composition of the present invention comprises a polymerizable monomer (A), inorganic particles (B), and a photopolymerization initiator (C) as constituent components, and a structural color having a predetermined color tone, Preferred is a method of producing a polymerization-curable composition that gives a cured product that develops a structural color having a predetermined color tone that does not depend on the incident angle of light. Here, the structural color having a predetermined color tone means that the constituent particles of G-PID have a specific short-range ordered structure and are dispersed in the resin matrix in the cured product, thereby diffracting in accordance with the Bragg condition. It means light having a color tone corresponding to the average primary particle diameter, which is caused by interference and enhancement of light having a specific wavelength. Further, each of the constituent particles dispersed in the cured body does not have long-range regularity, and by randomly dispersing as a whole, the structural color is not affected by the incident angle of light, and is expected. The color will start to develop.

As described above, even if the curable composition has the same composition and looks uniform, the optical properties of the cured product may change, and the cured product having the desired optical properties can be reliably and stably obtained. It is industrially important to manufacture. The present invention provides such a production method, and makes it possible to reliably produce a polymerization-curable composition that gives a cured product that develops a structural color having a predetermined color tone. Therefore, first, the final object "a cured product that develops a structural color having a predetermined color tone, preferably a structural color having a predetermined color tone that does not depend on the incident angle of light" will be described.

A cured product having such characteristics is disclosed in Japanese Patent Application Laid-Open No. H11-242, "the lightness (V) of a colorimetric value of a colored light under a black background measured by a Munsell color system, which is measured using a color difference meter. Is less than 5, the saturation (C) is 0.05 or more, and the lightness (V) of the colorimetric value of the colored light by the Munsell color system under the white background is 6 or more, and the saturation (C ) Is less than 2", but the following composite materials found by the present inventors and already proposed as Japanese Patent Application No. 2018-165680 are also included therein.
[Composite Material Proposed in Japanese Patent Application No. 2018-165680]: "A composite material in which inorganic particles are dispersed in a resin matrix, wherein the inorganic particles are (I) in a predetermined range of 100 to 1000 nm. It consists of an aggregate of inorganic spherical particles having an average primary particle diameter, and the individual inorganic spherical particles constituting the aggregate are composed of substantially the same substance, and all particles in the number-based particle size distribution of the aggregate. 90% or more of the number is present in a range of 5% before and after the predetermined average primary particle diameter, and one or more "spherical particle groups having the same particle size" (G-PID), and (II) average primary particle diameter Each consisting of inorganic particles having a particle size of less than 100 nm (G-SFP), wherein the number of the “spherical particle groups having the same particle size” contained in the inorganic particles is a. G-PID _m (where m is 1 when a is 1 and from 1 to a when a is 2 or more) in order of decreasing average primary particle size is a natural number. when expressed in) material wherein a constitutes the individual particles of the G-PID _m in the case of 2 or more may be different from each other, each G-PID _m when the The average primary particle diameters are different from each other by 25 nm or more, and the average primary particle diameter of the "ultrafine particle group" (G-SFP) is 25 nm or more smaller than the average primary particle diameter of the G-PID ₁ , When the refractive index at 25° C. of the resin matrix is n _(MX) and the refractive index at 25° C. of the inorganic spherical particles forming each G-PID _m is n _(G-PIDm) , which n _{(G -PIDm)}
n _(MX) <n _(G-PIDm)
And the arrangement structure of the inorganic spherical particles forming all the “spherical particle groups having the same particle size” (G-PID) in the resin matrix has a short-range ordered structure satisfying the following Condition 1 and Condition 2. The composite material described above.
[Condition 1] The distance from the center of any inorganic spherical particles dispersed in the composite material: r is divided by the average particle diameter of the entire inorganic spherical particles dispersed in the composite material: r ₀ , and standardized. A radial distribution function representing the probability that other inorganic spherical particles exist at a point separated by a distance r from the center of the arbitrary inorganic spherical particle, with the dimensionless number (r/r ₀ ) as the x-axis: g(r) In the radial distribution function graph showing the relationship between the r/r ₀ and the g(r) corresponding to r at that time with y as the y-axis, of the peaks appearing in the radial distribution function graph, The closest interparticle distance defined as r corresponding to the peak top of a near peak: r ₁ is a _value of 1 or more and 2 or less times the average particle diameter of all inorganic spherical particles dispersed in the composite material: r _0. Is.
[Condition 2] Of the peaks appearing in the radial distribution function graph, when r, which corresponds to the peak top of the second peak closest to the origin, is set as the next adjacent particle distance: r ₂ , the closest particle distance is : The minimum value of the radial distribution function: g(r) between r ₁ and the distance between adjacent particles: r ₂ is 0.56 or more and 1.10 or less. "
In the above composite material, fine particles having a uniform particle size are dispersed so as to have an amorphous structure as a whole while having a specific short-range ordered structure. Based on the fact that a structural color having a color tone can be developed in Patent Document 1, the method disclosed in Patent Document 1 is disclosed as a method for quantifying the dispersed state of spherical particles in the system of Patent Document 2. Utilizing a method for defining a short-range ordered structure using a radial distribution function in a plane: g(r)”, a fine filler or a plurality of spherical particles for adjusting the viscosity of a curable composition or for adjusting the contrast ratio of a cured product It was proposed based on the results of earnest studies on the case of using a filler aggregate. That is, the above-mentioned examination succeeds in specifying a short-range ordered structure that can obtain the above-mentioned effect in the system disclosed in Patent Document 2 (in other words, if the above-mentioned conditions 1 and 2 are satisfied, the above-mentioned effect is obtained). In addition, it has almost no effect on the structural color expression effect even if an extremely fine inorganic filler is added, and further, when specific conditions are satisfied, a plurality of spherical filler aggregates are added. Even if it is used, the short-range ordered structure type that develops a structural color in each spherical filler aggregate is maintained, the structural color due to each aggregate develops, and as a whole they develop a color tone that is synthesized, The present invention has led to the proposal by the present inventors. And the said hardened|cured material disclosed by patent document 2 contains only one kind of "spherical particle group with the same particle diameter" (G-PID) whose average particle diameter is in the range of 230-1000 nm, and "ultrafine particle group. "(G-SFP) is not particularly included, while the composite material has an average particle size of G-PID in the range of 100 to 1000 nm and contains one or more G-PIDs, and further contains a pre-cured composition. The difference is that G-SFP is added for the purpose of adjusting the viscosity and adjusting the contrast ratio of the cured product.

As described above, according to the studies made by the present inventors, if the above conditions 1 and 2 are satisfied, a cured product (composite material) that develops a structural color having a predetermined color tone independent of the incident angle of light is newly added. It is clear. Therefore, the cured product as the final object is a composite material having a short-range ordered structure that satisfies the conditions 1 and 2 although the G-SFP may or may not be included in the composite material. (Hereinafter, also referred to as “this complex”).

Therefore, next, after explaining the characteristic points relating to the specification of the “dispersion state of the inorganic spherical particles”, various raw materials used in the present composite material (which are also raw materials of the polymerization-curable composition of the present invention) are explained. Now, the manufacturing method of the present invention will be described.

In the present composite material, a short-range ordered structure is defined by using the “in-plane radial distribution function: g(r)” disclosed in Patent Document 1 as a method for quantifying the dispersed state of inorganic spherical particles. ing. Here, the radial distribution function g(r) is, as can be seen from the fact that it is used in Patent Document 1, the existence probability of another particle at a point separated by a distance r from an arbitrary particle. It is a well-known function for obtaining ##EQU1## and is defined by the following equation (1).
g(r)={1/<ρ>}×{dn/da} (1)
In the above formula (1), <ρ> represents the average particle density of particles in the plane, dn is the center of any particle in the plane, and two circles whose radii are r and r+dr, respectively. It represents the number of particles existing in the region between, and da represents the area of the region, 2πr·dr.

In general, the radial distribution function: g(r) has the distance r on the x-axis (distance axis) and the value of g(r) at r on the y-axis (vertical axis) {the above equation (1 )), or a dimensionless number standardized by dividing the r by the average particle size of the particles on the distance axis, and the value on the x axis on the y axis (vertical axis) It is represented by a radial distribution function graph that takes the value of g(r) (the calculation result of the above formula) at r corresponding to.

Since <ρ> and dn are easily and surely confirmed, <ρ> and dn determined based on a scanning electron microscope image in which the inner surface of the present composite material is an observation plane, and the above dn It is preferable to adopt g(r) calculated according to the above formula (1) based on the value of dr adopted when deciding: da(=2πr·dr).

The determination of <ρ>, dn, and da based on the scanning electron microscope image with the inner surface of the present composite material as the observation plane can be performed as follows. That is, first, the dispersion state of the inorganic spherical particles inside the composite material is obtained by means of curing the polymerization-curable composition or the like obtained in the present invention to prepare the present composite material, and polishing the surface of the obtained composite material. Exposes a plane (observation plane) on which the surface can be observed. Then, the observation plane is observed with a scanning electron microscope to obtain a microscope image of a region containing at least 500 inorganic spherical particles in at least the plane. After that, the coordinates of the inorganic spherical particles in the region are obtained from the obtained scanning electron microscope image using image analysis software (for example, “Simple Digitizer ver 3.2” free software). From the obtained coordinate data, select one coordinate of any inorganic spherical particle, draw a circle with a radius of a distance r containing at least 200 or more inorganic spherical particles around the selected inorganic spherical particle, and draw the circle. The average particle density <ρ> (unit: particles/cm ² ) can be determined by counting the number of inorganic spherical particles contained therein.

As for dn, when the average particle diameter of the inorganic spherical particles is represented by r ₀ , the length dr is set to a value of about r ₀ /100 to r ₀ /10 and arbitrarily selected 1 The number of inorganic spherical particles contained in a region between a circle having one inorganic spherical particle as a central particle and a radius of a distance r from the center and a circle having the same center as the circle and having a radius of r+dr. The dn can be determined by counting. Further, da, which is the area of the region between the two circles, is determined as 2πr·dr based on the actually set length of dr.

In the present composite material, the distance from the center of any inorganic spherical particles dispersed in the composite material: r is divided by the average particle diameter of the entire inorganic spherical particles dispersed in the composite material: r ₀ , and standardized Letting the number of dimensions (r/r ₀ ) be the x-axis, the radial distribution function: g(r), which represents the probability that other inorganic spherical particles exist at a distance r from the center of the arbitrary inorganic spherical particles, is represented by y. In the radial distribution function graph showing the relationship between the r/r ₀ and the g(r) corresponding to r at that time, the peak closest to the origin among the peaks appearing in the radial distribution function graph. The closest particle distance: r ₁ defined as r corresponding to the peak top of is a value of 1 to 2 times the average particle diameter of the entire inorganic spherical particles dispersed in the composite material: r _0. It is necessary (condition 1). When r ₁ is less than 1 times r ₀ (r ₁ /r ₀ <1), the particles in the plane overlap with each other, and r ₁ exceeds 2 times r ₀ (r ₁ In the case of /r ₀ >2), particles do not exist in the vicinity of the selected central inorganic particles, so that short-range order is lost and structural color is not developed. That is, from the viewpoint of maintaining order in a short distance and easily developing a structural color, r ₁ /r ₀ is 1.0 or more and 2.0 or less, particularly 1.0 or more and 1.5 or less. Preferably.

Further, in the present composite material, when r corresponding to the peak top of the second peak closest to the origin among the peaks appearing in the radial distribution function graph is set as the next interparticle distance: r ₂ , It is also necessary that the minimum value of the radial distribution function: g(r) between the interparticle distance: r ₁ and the next adjacent interparticle distance: r ₂ is a value of 0.56 or more and 1.10. 2). When the minimum value is less than 0.56, the long-range order of the arrangement structure of the inorganic spherical particles becomes high, and not only the incident angle dependence of the light of the structural color that develops but also the saturation of the composite material increases. Becomes high, and it becomes difficult to obtain color tone compatibility when used as a dental filling material. On the other hand, when the minimum value exceeds 1.10, the arrangement structure of the inorganic spherical particles becomes a random structure, which makes it difficult to obtain the desired reflection performance and makes it difficult to develop the desired structural color. .. That is, the minimum value is 0.56 or more and 1.10 or less, particularly 0.56 or more and 1.00 or less, from the viewpoint of developing a structural color and making it easier to obtain color tone compatibility as a dental filling material. Preferably.

According to the studies by the present inventors, in the curable composition (CR) disclosed in Patent Document 2, although the frequency is extremely low, it depends on the conditions when kneading the respective components to prepare the composition (CR). Shows that the desired effect may not be obtained in some cases, and when the above radial distribution function: g(r) is evaluated for such a system (where no effect is obtained), the condition 1 And/or 2 is not satisfied. This means that in the present composite material, the array structure of the inorganic spherical particles constituting the spherical particle group of the same particle size (G-PID) is correlated with the manufacturing conditions such as the kneading conditions of the raw materials. ing. That is, when the kneading conditions are likely to vary as in the case of manual kneading, the kneading conditions may not be sufficient with a certain probability, and the desired color tone conformance cannot be achieved without satisfying the condition 1 or the condition 2. Properties are not obtained, and the production yield is reduced. On the other hand, by adopting the method of the present invention, it becomes possible to surely satisfy the above conditions 1 and 2.

Next, the present composite material and a polymerization-curable composition for obtaining the same (a polymerization-curable composition which is an object of the production method of the present invention (hereinafter, also referred to as “the present polymerization-curable composition”)}. Details of various raw materials used and manufacturing methods will be described.

<Resin matrix>
The resin matrix in the present composite material is not particularly limited as long as it is made of a resin capable of allowing the inorganic spherical particles to be dispersed and present, and a thermoplastic resin or the like can be used, but the dispersion state of the inorganic spherical particles can be controlled. It is preferable that the cured product of the curable composition containing a polymerizable monomer as a main component is used because it is easy. Furthermore, from the viewpoint of ease of handling and physical properties (mechanical properties and adhesiveness to tooth material for dental use) when used as a dental filling/restoring material, a radical polymerizable monomer or cationic polymerizable monomer is used as a main component. A cured product of the curable composition is more preferred. Further, from the viewpoint of easily satisfying the above-mentioned condition regarding the refractive index, that is, the condition of n _(MX) <n _(G-PIDm) , the refractive index of the cured product at 25° C. is 1.40 to 1.57, particularly 1 It is particularly preferable that it is a cured product of the above curable composition such that it has a viscosity of 0.42 to 1.57.

<Polymerizable monomer (A)>
The radically polymerizable monomer (A) that can be preferably used to obtain the resin matrix is not particularly limited, and includes (meth)acrylic compounds, cationically polymerizable monomers such as epoxies and oxetanes, and the like. It can be appropriately selected and used. For example, in order to obtain a dental curable composition, it is preferable to use a (meth)acrylic compound. The (meth)acrylic compound may be either a monofunctional polymerizable monomer or a polyfunctional polymerizable monomer (as described in the above-mentioned Patent Document 2). It may have an acidic group or a hydroxyl group, and may be aromatic or aliphatic. Examples of (meth)acrylic compounds that can be suitably used for dental polymerizable cured products include methyl (meth)acrylate, ethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylic acid, and N-. (Meth)acryloylglycine, p-vinylbenzoic acid, 2-(meth)acryloyloxybenzoic acid, 6-(meth)acryloyloxyethylnaphthalene-1,2,6-tricarboxylic acid anhydride, 13-(meth)acryloyloxy Tridecane-1,1-dicarboxylic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, 2-hydroxyethyl(meth)acrylate, 3-hydroxypropyl(meth)acrylate, N-hydroxyethyl(meth)acrylamide , N,N-(dihydroxyethyl)(meth)acrylamide, 2,2-bis(methacryloyloxyphenyl)propane, 2,2-bis[(3-methacryloyloxy-2-hydroxypropyloxy)phenyl]propane, ethylene glycol Examples thereof include dimethacrylate, triethylene glycol dimethacrylate, 1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, and 4,4-diphenylmethane diisocyanate.

These (meth)acrylate-based polymerizable monomers may be used in combination of a plurality of types, if necessary.

As the polymerizable monomer, generally, a plurality of types of polymerizable monomers are used for the purpose of adjusting the physical properties of the cured product which becomes the resin matrix (mechanical properties and adhesiveness to tooth in dental applications). At this time, the type and amount of the polymerizable monomer may be set so that the refractive index of the polymerizable monomer composition (mixture) at 25° C. is in the range of 1.38 to 1.55. It is desirable from the viewpoint of easily satisfying the condition regarding the refractive index. That is, when a silica-titanium group element oxide-based composite oxide whose refractive index is easily adjusted is used as the inorganic spherical particles, the refractive index at 25° C. is 1.45 to 1.58 depending on the content of silica. By setting the refractive index of the polymerizable monomer composition in the range of 1.38 to 1.55, the refractive index of the cured product obtained is approximately 1.40 to 1.57. The range can be adjusted, and it becomes easy to satisfy the above conditions. The refractive index of the polymerizable monomer or the cured product of the polymerizable monomer can be determined at 25°C using an Abbe refractometer.

<Inorganic particles (B)>
In the present composite material, the inorganic particles (B) dispersed in the resin matrix include one or more "spherical particle groups having the same particle size" (G-PID).

<Spherical particle group having the same particle size: G-PID>
Spherical particle group having the same particle diameter: G-PID is composed of an aggregate of inorganic spherical particles having a predetermined average primary particle diameter within the range of 100 nm or more and 1000 nm or less (100 to 1000 nm), and constitutes the aggregate. The individual inorganic spherical particles are composed of substantially the same substance, and 90% or more of the total number of particles in the number-based particle size distribution of the aggregate is within a range of 5% before and after the predetermined average primary particle size. Existing in the above, the above aggregate is meant.

The average primary particle diameter of the inorganic spherical particles referred to here is a primary electron of each of primary particles selected from 30 or more particles observed in a unit field of view of a G-PID photograph taken by a scanning electron microscope. It means the average value of the particle diameter (maximum diameter). Further, the spherical shape may be a substantially spherical shape, and does not necessarily have to be a perfect true sphere. Take a picture of G-PID with a scanning electron microscope, measure the maximum diameter of each particle (30 or more) within the unit field of view, and divide the particle diameter in the direction orthogonal to the maximum diameter by the maximum diameter. It is sufficient that the average degree of uniformity is 0.6 or more, more preferably 0.8 or more.

In this composite material, the constituent inorganic particles are spherical, and each constituent particle of G-PID, which is an aggregate of inorganic particles having a narrow particle size distribution (number-based particle size distribution), has a specific short-range ordered structure. By being dispersed in the resin matrix, diffraction interference occurs according to the Bragg condition, light of a specific wavelength is emphasized, and colored light having a color tone corresponding to the average primary particle diameter is generated (structural color is developed). That is, in order to develop the structural color, 90% (number basis) or more of the inorganic spherical particles constituting the G-PID must be present in the range of 5% before and after the average primary particle diameter. Further, the average primary particle diameter of the inorganic spherical particles constituting the G-PID is in the range of 100 to 1000 nm in order to develop a structural color having a specific color tone within a wide range of blue to yellow to red. There is a need. When spherical particles having an average primary particle size of less than 100 nm are used, the visible light interference phenomenon is unlikely to occur and the structural color is also difficult to develop. On the other hand, when spherical particles having a size of more than 1000 nm are used, the phenomenon of light interference can be expected, but when the curable composition of the present invention is used as a restoration material for dental filling, sedimentation or polishing of spherical particles is performed. This is not preferable because it causes deterioration of sex.

When the average primary particle size is 230 to 800 nm, a yellow to red structural color (colored light) is likely to appear, and when the average primary particle size is 150 nm to less than 230 nm, a blue structural color ( Colored light) is easy to develop.

The average primary particle diameter of G-PID is preferably 230 to 800 nm, more preferably 240 to 500 nm, because it exhibits a yellow to red structural color (colored light) that is preferable as a dental filling/restoring material. , 260 to 350 nm is particularly preferable. When using the G-PID having an average primary particle diameter in the range of 230 nm to 260 nm, the obtained colored light is yellowish, and falls within the category of B-type (red-yellow) in the shade guide (“VITAC Classic”, manufactured by VITA). It is useful for the repair of certain teeth, especially for the repair of cavities formed from enamel to dentin. Further, when G-PID having an average primary particle diameter of 260 nm to 350 nm is used, the obtained colored light is red, and the shade guide (“VITAC Classic”, manufactured by VITA) has a category of A (red brown). It is useful for the restoration of the tooth in the above, and is especially useful for the restoration of the cavity formed from the enamel to the dentin. Since the dentin has many reddish hues, it is widely applicable to restoration teeth of various tones in the aspect in which only G-PID having an average primary particle size of 260 nm to 350 nm is used, and the most suitable. preferable. On the other hand, when only G-PID having a particle size in the range of 150 nm to less than 230 nm is used, as described above, the colored light obtained is bluish, and the cavities formed from the enamel to the dentin are used. Has a poor color tone compatibility with the tooth substance, but is useful for restoration of enamel, and particularly useful for restoration of incisal portion.

In the present composite material, the G-PID contained in the inorganic particles dispersed in the resin matrix may be one kind or plural kinds. The number of G-PIDs included: a is preferably 1 to 5, particularly preferably 1 to 3, and most preferably 1 or 2.

However, when a plurality of types of G-PID are contained in the inorganic particles, the average primary particle size of each G-PID _m needs to be different from each other by 25 nm or more. That is, when the number of G-PID contained in the inorganic particles is “a” (for example, “3”), G-PID _m (however, m Is 1 when a is 1, and is a natural number from 1 to a when a is 2 or more.), each G-PID _m (for example, G when a=3) -PID ₁ , G-PID ₂ and G-PID ₃ ) The substances constituting the individual particles may be different from each other, but when the average primary particle diameter of each G-PID _m in that case is d _m. , D _m differ from each other by 25 nm or more (for example, when a=3, |d ₁ −d ₂ |≧25 nm, |d ₂ −d ₃ |≧25 nm, and of course |d ₁₋ d ₃ |≧25 nm). By satisfying this condition, for example, each G-PID can be dispersed in the form of an aggregate in which a small number of inorganic spherical particles that do not exceed about 20 aggregate with a very loose binding force. , G-PID can be dispersed with a short-range ordered structure capable of expressing a structural color, but as a result, each G-PID has a unique structure (according to the average primary particle diameter). It becomes possible to express a color. On the other hand, when this condition is not satisfied, the particle size distribution of the entire inorganic spherical particles becomes broad, and the inorganic spherical particles constituting each G-PID are likely to be mutually substituted and dispersed, and the number standard This is probably due to the same phenomenon as when a single aggregate of inorganic spherical particles that does not satisfy the condition of particle size distribution is used, but it becomes difficult to develop a structural color.

When using a plurality of G-PID in the composite material of the present invention, the average primary particle diameter _{d m} of the G-PID _m are each mutually 30nm or more, are different particularly 40nm or more (that is, _{d m} and _{d m-1} Is preferably 30 nm or more, particularly 40 nm or more). The difference between d _m and d _m-1 is preferably 100 nm or less, and particularly preferably 60 nm or less.

<Inorganic spherical particles>
The inorganic spherical particles forming the G-PID are not particularly limited in material as long as they satisfy the above-mentioned conditions for forming the G-PID. Examples of materials that can be preferably used include amorphous silica, silica-titanium group element oxide-based composite oxide particles (silica-zirconia, silica-titania, etc.), quartz, alumina, barium glass, strontium glass, lanthanum glass. , Fluoroaluminosilicate glass, ytterbium fluoride, zirconia, titania, colloidal silica and the like. Among these, it is preferable to use particles composed of a silica-titanium group element oxide-based composite oxide because the refractive index can be easily adjusted.

Here, the silica-titanium group element oxide-based composite oxide particles mean a composite oxide of silica and a titanium group element (element of Group 4 of the periodic table) oxide, and it depends on the content of silica. The refractive index at 25° C. can be changed within the range of 1.45 to 1.58. Specific examples of the silica-titanium group element oxide-based composite oxide particles include silica-titania, silica-zirconia, silica-titania-zirconia, and among these, high X-ray opacity Silica zirconia is preferably used because it can be added. The composite ratio of silica/zirconia is not particularly limited, but the content of silica is 70 to 95 mol% from the viewpoint of imparting sufficient X-ray opacity and making the refractive index into a suitable range described later. It is preferable that the content of the titanium group element oxide is 5 to 30 mol %.

It should be noted that these silica/titanium group element oxide-based composite oxide particles may be a composite of metal oxides other than silica and titanium group element oxides, as long as the amount is small. Specifically, an alkali metal oxide such as sodium oxide or lithium oxide may be contained within 10 mol%.

The method for producing such silica/titanium group element oxide-based composite oxide particles is not particularly limited, but in order to obtain a spherical filler, for example, a hydrolyzable organosilicon compound and a hydrolyzable organotitanium group metal compound are used. A so-called sol-gel method, in which a mixed solution containing a is added to an alkaline solvent to cause hydrolysis to precipitate a reaction product, is preferably adopted.

The inorganic spherical particles composed of these silica/titanium group element oxide-based composite oxides may be surface-treated with a silane coupling agent. The surface treatment with the silane coupling agent makes the organic-inorganic composite filler excellent in interfacial strength between the organic-inorganic composite filler and the organic resin matrix, as described below. Examples of typical silane coupling agents include organic silicon compounds such as γ-methacryloyloxyalkyltrimethoxysilane and hexamethyldisilazane. The surface treatment amount of these silane coupling agents is not particularly limited, and the optimum value may be determined after confirming the mechanical properties and the like of the cured product of the obtained curable composition in advance by experiments, but a suitable range is set. For example, it is in the range of 0.1 to 15 parts by mass with respect to 100 parts by mass of the inorganic spherical particles.

<Relationship between refractive index of resin matrix and inorganic spherical particles>
In the present composite material, when the refractive index at 25° C. of the resin matrix is n _(MX) and the refractive index at 25° C. of the inorganic spherical particles constituting each G-PID _m is n _(G-PIDm). In addition, the following relationship must be established for any n _(G-PIDm) .
n _(MX) <n _(G-PIDm)
If the above relationship is not satisfied, short-wavelength light is likely to be scattered in the resin matrix even if the structural color is developed, and it is difficult to confirm the developed structural color. From the viewpoints of the visibility and sharpness of the developed structural color and the color tone compatibility when used as a dental filling/restoring material, the difference between n _(G-PIDm) and n _(MX) is Δn(=n _{(G -PIDm)} -n _(MX) ) is preferably 0.001 or more and 0.1 or less, more preferably 0.002 or more and 0.1 or less, and 0.005 or more, 0.05. Most preferably it is

As described above, by setting the refractive index of the polymerizable monomer (which may be a mixture) at 25°C to the range of 1.38 to 1.55), the cured product of the resin matrix becomes 25°C. The refractive index (n _(MX) ) in can be in the range of 1.40 to 1.57. Further, as described above, the silica-titanium group element oxide-based composite oxide has a refractive index (n _(G-PIDm) ) at 25°C of _{1.45 to} 1 by changing the content of silica. It can be changed within a range of about 0.58. Therefore, by utilizing these relationships, for example, Δn can be easily set within the preferable range.

<Ultrafine particle group: G-SFP>
The ultrafine particle group (G-SFP) is a particle aggregate composed of inorganic particles having an average primary particle size of less than 100 nm, and is a precursor of the present composite material (a material for obtaining a composite material by curing). It may be blended for the purpose of adjusting the viscosity of the composition, or for adjusting the contrast ratio of the present composite material. However, the average primary particle diameter of G-SFP is 25 nm or more smaller than the average primary particle diameter (d ₁ ) of G-PID ₁ , which has the smallest average maintenance particle diameter among the G-PID mixed in the inorganic particles. There is a need. If these conditions are not satisfied, the dispersed state of the inorganic spherical particles is adversely affected, and the structural color is difficult to develop. The shape of the inorganic particles forming the G-SFP is not particularly limited, and may be amorphous or spherical. The lower limit of the average primary particle size is usually 2 nm.

The average primary particle diameter of the G-SFP when G-SFP is added is preferably 3 nm or more and 75 nm or less, and particularly preferably 5 nm or more and 50 nm or less, because the effect on the structural color expression is small. For the same reason, the average primary particle diameter (d ₁ ) of G-PID ₁ is preferably 30 nm or more, and particularly preferably 40 nm or more.

As the material of the inorganic particles constituting the G-SFP, the same materials as the inorganic spherical particles can be used without particular limitation. Further, a surface treatment with a silane coupling agent can be performed in the same manner as the inorganic spherical particles. The preferred embodiment is also basically the same as the inorganic spherical particles except for the average primary particle size and shape.

<Relationship between the present composite material and the present curable composition>
The present composite material can be suitably produced by polymerizing and curing the present polymerization curable composition. Further, the mixing ratio of each component in the present composite material is almost uniquely determined by the composition of the present polymerization curable composition. Furthermore, it is considered that the dispersion state (dispersion structure) of the inorganic spherical particles in the present composite material is substantially maintained as it is in the dispersion state (dispersion structure) of the inorganic spherical particles in the polymerization-curable composition immediately before curing. Be done. That is, although there is a possibility of being affected by polymerization shrinkage or the like that occurs at the time of curing, the effect is small, and it does not exert such an effect that the conditions 1 and 2 are satisfied or not.

<Main polymerization curable composition>
The polymerization-curable composition comprises the polymerizable monomer (A), particularly a polymerizable monomer that gives a cured product having a refractive index of 1.40 to 1.57 at 25° C., in the range of 100 to 1000 nm. The spherical particles are composed of a group of spherical particles having an average primary particle diameter of a predetermined length, and the individual particles constituting the spherical particle group are composed of substantially the same substance and 90% (number) or more of the individual particles. Is present in a range of 5% before and after the average primary particle size, and is blended with one or more "spherical particle groups having the same particle size" (G-PID), if necessary, the particle size is less than 100 nm and the above 1 or "Ultrafine particles" composed of inorganic particles having an average primary particle size smaller by 25 nm or more than the smallest average primary particle size among the average primary particle sizes of a plurality of "same particle size spherical particle groups" (G-PID) Spherical particles that contain the group "(G-SFP)" and the inorganic particles (B) containing the group and a photopolymerization initiator (C), and constitute the "Spherical particle group with the same particle size" (G-PID). Has a higher refractive index than the cured product at 25° C. In addition, by polymerizing and curing this, a cured product, that is, the present composite material, that develops a structural color having a predetermined color tone that does not depend on the incident angle of light is provided.

The present polymerizable curable composition is particularly preferably used as a dental curable composition, particularly as a dental filling and restorative material represented by a photocurable composite resin, but is not limited thereto and other dental applications. Can also be suitably used. Examples of its use include dental cement and restorative materials for abutment construction.

<Polymerizable monomer (A) component and inorganic particle (B) component>
The polymerizable monomer (A) in the present curable composition is the same as the polymerizable monomer (A) described as the raw material for the resin matrix of the present composite. Further, the G-PID and the inorganic spherical particles constituting the G-PID are the same as those described as the constituent components of the present composite.

The amount of the spherical particles having the same particle diameter: G-PID is usually the total amount of all G-PID contained (that is, the total amount of the inorganic spherical particles), relative to 100 parts by mass of the polymerizable monomer (A) component. And 10 parts by mass to 1500 parts by mass. For the reason that the present composite material has appropriate transparency and the effect of expressing the structural color is also high, the amount of G-PID blended is 50 parts by mass with respect to 100 parts by mass of the polymerizable monomer (A) component. -1500 parts by mass is preferred, and 100 parts by mass-1500 parts by mass is particularly preferred. In addition, the compounding quantity of each G-PID in the case of including a plurality of kinds of G-PID is within the above range in consideration of the color tones of the structural color by each G-PID and the desired color tone in the composite material. It may be appropriately distributed by the amount.

Although the addition of the ultrafine particle group: G-SFP is optional, the blending amount in the case of adding may be appropriately determined in consideration of the viscosity of the polymerization-curable composition and the contrast ratio of the composite material. .. The usual addition amount is 0.1 to 50 parts by mass, and preferably 0.2 to 30 parts by mass, relative to 100 parts by mass of the polymerizable monomer (A) component.

<Photopolymerization initiator (C)>
The photopolymerization initiator (C) in the present polymerization-curable composition is not particularly limited as long as it has a function of polymerizing and curing the polymerizable monomer.

Examples of the photopolymerization initiator (C) include 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 and 4,4′-dimethyl. Benzophenone, benzophenones such as 4-methacryloxybenzophenone, α-diketones such as diacetyl, 2,3-pentadionebenzyl, camphorquinone, 9,10-phenanthraquinone, and 9,10-anthraquinone, 2,4- Thioxanthone compounds such as diethoxythioxanthone, 2-chlorothioxanthone and methylthioxanthone, bis-(2,6-dichlorobenzoyl)phenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-2,5- Dimethylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis-(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis(2,4,6-trimethylbenzoyl) )-Bisacylphosphine oxides such as phenylphosphine oxide can be used.

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

Furthermore, in addition to the above-mentioned photopolymerization initiator and reducing compound, an example in which a photoacid generator is added is often found. Examples of such a photoacid generator include diaryliodonium salt compounds, sulfonium salt compounds, sulfonate compounds, halomethyl-substituted-S-triazine derivatives, pyridinium salt compounds, and the like.

These polymerization initiators may be used alone, or two or more kinds may be mixed and used. Although the compounding amount of the polymerization initiator may be selected in accordance with the purpose, an effective amount is usually 0.01 to 10 parts by mass with respect to 100 parts by mass of the polymerizable monomer (A), and more preferably It is used in a proportion of 0.1 to 5 parts by mass.

<Preferred embodiment of the present curable composition>
In the present polymerization-curable composition, at least one of the one or more "spherical particle groups having the same particle size" (G-PID) is used because the short-range ordered structure can be obtained more easily and reliably. The part is one kind of "spherical particle group of the same particle size" (G-PID) and the inorganic spherical particle whose refractive index at 25°C constitutes the one "spherical particle group of the same particle size" (G-PID). An organic compound containing a resin having a refractive index smaller than that of the above, and containing no "spherical particle group having the same particle size" (G-PID) other than the one kind of "spherical particle group having the same particle size" (G-PID). Inorganic composite filler (Organic-Inorganic Hybrid Filler), in other words, "organic-inorganic composite filler containing only a single G-PID" is preferably blended.

Here, the organic-inorganic composite filler is a powder composed of a composite in which the inorganic filler is dispersed in an (organic) resin matrix, or an aggregate in which primary particles of the inorganic filler are bound by an (organic) resin. Means filler.

In the preferred embodiment, for example, when three types of G-IDPs having different average primary particle diameters, that is, G-PID ₁ , G-PID ₂ and G-PID _3, are included, all or a part of at least one of them is included. Is to be blended as an "organic-inorganic composite filler containing only a single G-PID". If all of the G-PID ₁ organic containing only G-PID ₁ - when incorporated into the polymerization curable composition as an inorganic composite filler (complex filler 1) has, within the composite filler 1, G-PID ₁ Since the short-range ordered structure that develops the structural color of G-PID ₁ is realized because it contains only only G-PID ₁ , even in the present composite obtained by curing the present polymerization-curable composition, G -The structural color of PID ₁ develops. That is, when G-PID ₁ is blended without forming a composite filler, it is kneaded with G-PID ₂ and G-PID ₃ that are blended at the same time (without being complexed), and therefore, to a certain extent. , (The G-PID ₁ constituent particles and G-PID ₃ constituent particles are mutually substituted), and the closest particles of certain inorganic spherical particles constituting G-PID ₁ are the inorganic particles constituting G-PID _3. Therefore, it is considered that the short-range ordered structure is destroyed in the region around the certain inorganic spherical particle. On the other hand, when all of G-PID ₁ is blended as the composite filler 1, mutual substitution of particles as described above does not occur, and the short-range ordered structure is not destroyed, which is involved in structural color expression. The proportion of the inorganic spherical particles that do not exist can be made as small as possible, and the structural color of G-PID ₁ can be reliably exhibited even in the present composite body after curing. Similarly, organic containing a G-PID ₂ and / or G-PID ₃ only G-PID ₂ - inorganic composite filler organic containing only (composite filler 2) and / or G-PID ₃ - inorganic composite filler (complex filler By blending as 3), it becomes possible to surely express these structural colors.

From the viewpoint that such effects can be expected and the viscosity of the present polymerization curable composition can be easily adjusted, 10% to 90%, particularly 20% to 80%, and further 30% to 70% of each G-PID. Is preferably blended with "organic-inorganic composite filler containing only a single G-PID".

When G-PID is blended in a form other than "organic-inorganic composite filler containing only a single G-PID", it is blended in the form of powder (G-PID itself as an inorganic spherical particle aggregate). Although it is general, it is also possible to mix it as an organic-inorganic composite filler containing a plurality of types of G-PID. The organic-inorganic composite filler will be described in more detail below including this case.

<Organic-inorganic composite filler>
As described above, the organic-inorganic composite filler is a powder composed of a composite in which the inorganic filler is dispersed in the (organic) resin matrix, or an aggregate in which primary particles of the inorganic filler are bound by the (organic) resin. Means a filler consisting of.

In the organic-inorganic composite filler used in the present curable composition, inorganic spherical particles are used as the inorganic filler, and the refractive index at 25° C. of the inorganic spherical particles is used as the resin constituting the (organic) resin matrix. A smaller resin is used. The resin is not particularly limited as long as it satisfies such conditions, but is preferably a cured body of the polymerizable monomer used when producing the resin matrix of the present composite material. At this time, it is not necessary that the composition of the polymerizable monomer component of the present polymerizable curable composition is exactly the same, but the refractive index at 25°C is equal to the refractive index of the polymerizable monomer component at 25°C. It is preferable to use the following. Further, when the refractive index of the resin (Resin) at 25° C. is n _(R) and the refractive index of the inorganic spherical particles at 25° C. is n _(F) , in any organic-inorganic composite filler,
n _(R) <n _(F)
The relationship must be established. When the organic-inorganic composite filler contains inorganic spherical particles having different refractive indexes at 25°C, this relationship needs to hold for all the inorganic spherical particles. Δn(=n _(F) −n _(R) ), which is the difference between n _(F) and n _(R) , is preferably 0.001 or more and 0.01 or less, and 0.001 or more, 0 or less. It is more preferably 0.005 or less.

The content of the inorganic spherical particles in the organic-inorganic composite filler is preferably 30% by mass or more and 95% by mass or less. When the content in the organic-inorganic composite filler is 30% by mass or more, the colored light of the cured product of the curable composition comes to be exhibited well, and the mechanical strength can be sufficiently increased. Further, it is difficult in operation to contain the inorganic spherical particles in the organic-inorganic composite filler in an amount of more than 95% by mass, and it becomes difficult to obtain homogeneous particles. A more preferable content of the inorganic spherical particles in the organic-inorganic composite filler is 40 to 90% by mass.

The organic-inorganic composite filler is generally a mixture of inorganic spherical particles, a polymerizable monomer, and a predetermined amount of each component of a polymerization initiator, polymerized by a method such as heating or light irradiation, and then pulverized. Can be manufactured according to various manufacturing methods. According to such a production method, an amorphous organic-inorganic composite filler composed of a composite in which inorganic spherical particles are dispersed in a resin matrix can be obtained.

In addition, the method described in International Publication No. 2011/115007 and International Publication No. 2013/039169 pamphlets, that is, agglomerated particles composed of agglomerates of inorganic spherical particles, a polymerizable monomer, a polymerization initiator and It can also be produced by a method of dipping in a liquid composition containing an organic solvent, removing the organic solvent, and polymerizing and curing the polymerizable monomer by heating or light irradiation. By such a method, the resin covers at least a part of the surface of each primary particle while the primary particles of the inorganic spherical particles are kept substantially agglomerated, and the respective primary particles are bonded to each other to communicate with the outside. It is possible to obtain a porous organic-inorganic composite filler having a large number of fine pores.

The average particle size of the organic-inorganic composite filler is not particularly limited, but from the viewpoint of improving the mechanical strength of the cured product and the operability of the curable paste, it is preferably 2 to 100 μm, and 5 to It is preferably 50 μm, particularly preferably 5 to 30 μm.

In the organic-inorganic composite filler, a pigment, a polymerization inhibitor, and a fluorescent substance are used within a range that does not impair the effect (usually 0.0001 to 5 parts by mass relative to 100 parts by mass of the organic-inorganic composite filler). A whitening agent or the like can be added. Further, the organic-inorganic composite filler may be subjected to cleaning or surface treatment with a silane coupling agent or the like.

The compounding amount of the organic-inorganic composite filler in the present curable composition is the same as that of the spherical particles of the same particle size: G-PID, which are contained in the curable composition of the present invention and which are not formed into the organic-inorganic composite filler. In consideration of the amount, the total amount of all G-PID contained (that is, the total amount of the inorganic spherical particles) is determined by converting from the amount of the inorganic spherical particles contained in the organic-inorganic composite filler so as to be the above-mentioned amount. do it.

<Other additives>
The present polymerization curable composition may be blended with other known additives in addition to the components (A) to (C) as long as the effects thereof are not impaired. Specific examples include a polymerization inhibitor and an ultraviolet absorber. Further, for the purpose of adjusting viscosity and the like, a filler having a particle size sufficiently smaller than the wavelength of light and hardly affecting the color tone and transparency can be blended.

As described above, the composite material of the present invention obtained from the present polymerization curable composition develops a structural color without using a coloring substance such as a pigment. Therefore, it is not particularly necessary to mix the curable composition of the present invention with a pigment that may change color over time. However, the compounding of the pigment itself is not denied, and the pigment may be compounded to the extent that it does not hinder the colored light due to the interference of the spherical filler. Specifically, about 0.0005 to 0.5 parts by mass, preferably about 0.001 to 0.3 parts by mass of pigment may be added to 100 parts by mass of the polymerizable monomer. ..

Next, the manufacturing method of the present invention will be described.
The production method of the present invention is a method of producing the curable composition of the present invention, in which the polymerizable monomer (A), the inorganic particles (B) and the photopolymerization initiator (C) are mixed. Including steps. In the mixing step, the required amounts of the components (A) to (C) are weighed, and these are mixed. The weighing method and the mixing method of each component at this time are not particularly limited, but as for the mixing method, it is said that the curable composition of the present invention is homogenized in a mixed state in a short time and scale-up production is easy. For the reason, it is preferable to mix using a kneading device such as a planetary motion type agitator.

In the method of the present invention, in the mixing, the dispersion state of the inorganic particles (B) in the cured product obtained by curing the mixture is the above conditions (I) and (II). It is necessary to adopt the mixing conditions that have been confirmed to satisfy Here, the conditions (I) and (II) to be satisfied with the cured product of the mixture are the same as the conditions 1 and 2 to be satisfied with the present composite, and the term “the present composite material” in the conditions 1 and 2 is used. Since it is replaced with "cured product of mixture", detailed description will be omitted.

In the mixing step, (1) separately using a composition having the same or substantially the same composition as the polymerization-curable composition to be actually produced, mixing is performed by changing a plurality of mixing conditions. By examining the radial distribution function: g(r) in the cured product of the mixture obtained when mixed under the mixing conditions, the mixing conditions satisfying the above conditions (I) and (II) are determined, The same mixing condition as the determined mixing condition is adopted, or (2) a part of the mixture obtained during and/or after the mixing step is sampled, and the sampled mixture in the cured product is used. It is preferable to confirm whether or not the dispersed state of the inorganic particles (B) satisfies the conditions (I) and (II), and continue mixing until the conditions are satisfied (see FIG. 1).

For example, a kneading method using a planetary motion type agitator (planetary mixer) is adopted as a mixing method, and the same composition as a polymerization-curable composition actually manufactured by using the above-mentioned (1) an actually used apparatus. Each raw material is charged so that the rotation speed, kneading time, and various conditions such as the post-kneading method of demixing are changed, and the mixed kneading is performed multiple times. The radial distribution function g(r) of the cured product may be examined to determine the condition for providing the cured product that satisfies the conditions 1 and 2, and the condition may be adopted. As a defoaming method, it is preferable to adopt a method of defoaming under reduced pressure because bubbles can be removed in a short time even from a composition having high viscosity. In such a method (1), the intended main polymerization-curable composition can be reliably produced only by setting a predetermined kneading condition, and therefore, the same composition (same composition and same amount) is used every time. (2) To improve the efficiency of work in that the present polymerization-curable composition does not need to be changed in condition every time and excessive kneading (kneading for an unnecessarily long time) can be prevented. You can

Further, the method (2) can be said to be a particularly preferable method when producing the curable composition of the present invention having a different composition or amount each time.

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

Each of the composite materials of Examples and Comparative Examples was obtained by curing a polymerization-curable composition containing a polymerizable monomer, inorganic particles and a polymerization initiator. First, each component used in the polymerization-curable composition used in Examples and Comparative Examples will be described.

1. Polymerizable Monomer M1 which is a polymerizable monomer mixture having the composition shown in Table 1 was used. The abbreviations in the polymerized monomer column in the table represent the following compounds, and the numbers in parentheses after the abbreviations represent the parts by mass used.
UDMA: 1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane 3G: triethylene glycol dimethacrylate Further, the viscosity of M1 is constant temperature of 25°C using an E-type viscometer (Tokyo Seiki: VISCONIC ELD). It was measured in the room.
Further, the refractive index before curing (M1) and the refractive index after curing (cured product) were measured using an Abbe refractometer (manufactured by Atago Co.) in a thermostatic chamber at 25°C. At this time, the cured product sample was 0.2% by mass of camphorquinone (CQ) (as a photopolymerization initiator), and p-N,N-dimethylaminoethyl benzoate (100% by mass of M1 or M2). DMBE) (0.3% by mass) and hydroquinone monomethyl ether (HQME) (0.15% by mass) were added and uniformly mixed, and the mixture was put into a mold having a through hole of 7 mmφ×0.5 mm, and a polyester film was formed on both sides. After press contacting, a halogen type dental light irradiator with a light amount of 500 mW/cm ² (Demetron LC, manufactured by CYBRON Co., Ltd.) was used for 30 seconds of light irradiation for curing, followed by removal from the mold. In addition, when setting the cured sample to the Abbe refractometer, a solvent (bromonaphthalene) that does not dissolve the sample and has a higher refractive index than the sample is used as the sample in order to bring the cured sample and the measurement surface into close contact. Dropped.

2. Inorganic particles 2-1. Spherical particle group with the same particle size (G-PID)
As G-PID, G-PID1 to G-PID8 shown in Table 2 were used. These spherical particles having the same particle size were prepared according to the method described in JP-A-58-110414 and JP-A-58-156524 (so-called sol-gel method). Specifically, first, a hydrolyzable organosilicon compound (such as tetraethyl silicate) and a hydrolyzable organotitanium group metal compound (such as tetrabutyl zirconate and tetrabutyl titanate) are shown in the composition column of Table 2. A mixed solution containing such a composition is added to a solution of ammoniacal alcohol (for example, methanol, ethanol, isopropyl alcohol, isobutyl alcohol, etc.) in which ammonia water is introduced, and hydrolysis is performed to obtain a reaction product. It was deposited. Next, the precipitate was separated, dried, and optionally crushed and then calcined to obtain the calcined product.

Then, 4 parts by mass of γ-methacryloyloxypropyltrimethoxysilane and 3 parts by mass of n-propylamine are mixed with stirring in 500 parts by mass of methylene chloride with respect to 100 parts by mass of the obtained baked product, and methylene chloride is evaporated with an evaporator. After removing, it was dried by heating at 90° C. to obtain a surface-treated product of spherical particles having the same particle size.

Further, the average particle diameter in Table 2 (inorganic spherical particles means the average primary particle diameter), ±5% internal particle ratio [exists in the range of 5% before and after the average primary particle diameter in the number-based particle size distribution] It means the ratio (%) of the number of particles to the total number of particles. ], the average uniformity and the refractive index were measured as follows.

(1) Average primary particle diameter A photograph of powder was taken with a scanning electron microscope ("XL-30S" manufactured by Philips) at a magnification of 5000 to 100000 times, and image analysis software ("IP-1000PC", trade name; Asahi Kasei Engineering Co., Ltd.) is used to process the photographed image, the number of particles (30 or more) observed in the unit field of view of the photograph and the primary particle diameter (maximum diameter) are measured, and the measured values are obtained. Based on the following formula, the number average primary particle diameter was calculated.

(2) Particle ratio within ±5% [ratio of the number of particles existing in the range of 5% before and after the average primary particle diameter in the number-based particle size distribution to the total number of particles (%)]
Among all particles (30 or more) in the unit field of view of the above photograph, the number of particles having a primary particle diameter (maximum diameter) outside the particle diameter range of 5% of the average primary particle diameter obtained above was measured. Then, the value is subtracted from the total number of particles to obtain the number of particles within a particle diameter range of 5% before and after the average primary particle diameter in the unit visual field of the photograph, and the following formula:
Particle ratio within ±5% (%)=[(number of particles within 5% particle size range before and after the average primary particle diameter in the unit field of view of the scanning electron microscope photograph)/(in the unit field of view of the scanning electron microscope photograph) Total number of particles in))]×100
Was calculated according to.

(3) Average uniformity The number of particles (n: 30 or more) of particles of the spherical particle group (G-PID) having the same particle size observed in a unit field of view of a powder photographed by a scanning electron microscope. ), the maximum diameter of the particles is the long diameter (Li), and the diameter in the direction orthogonal to the long diameter is the short diameter (Bi), and calculated by the following formula.

(4) Refractive index The refractive index was measured by the liquid immersion method using an Abbe refractometer (manufactured by Atago Co., Ltd.). That is, a spherical particle group (G-PID) having the same particle size is dispersed in 50 ml of anhydrous toluene in a 100 ml sample bottle in a thermostatic chamber at 25°C. While stirring this dispersion with a stirrer, 1-bromotoluene was added dropwise little by little, and the refractive index of the dispersion at the time when the dispersion became most transparent was measured. G-PID).

2-2. Production of organic-inorganic composite filler (CF1) 10 kg of spherical particle group (G-PID5) having the same particle size shown in Table 2 was added to 20 kg of water, and these were added using a circulation type pulverizer SC mill (manufactured by Nippon Coke Industry Co., Ltd.). An aqueous dispersion of was obtained.
On the other hand, 400 g (1.60 mol) of γ-methacryloyloxypropyltrimethoxysilane and 0.3 g of acetic acid were added to 8 kg of water and stirred for 1 hour and 30 minutes to obtain a uniform solution of pH 4. This solution was added to the above particle size particle group dispersion liquid and mixed until uniform. Then, the dispersion liquid was lightly mixed and supplied onto a disk rotating at a high speed, and granulated by a spray drying method.
The spray drying was performed using a spray dryer TSR-2W (manufactured by Sakamoto Giken Co., Ltd.), which is equipped with a rotating disk and atomizes by centrifugal force. The rotation speed of the disk was 10,000 rpm, and the temperature of the dry atmosphere air was 200°C. Then, the powder obtained by granulation by spray drying was vacuum dried at 60° C. for 18 hours to obtain 7.3 kg of a substantially spherical aggregate.
Next, 1.2 kg of M1 as a polymerizable monomer, 3.0 g of azobisisobutyronitrile (AIBN) as a thermal polymerization initiator, and 600 g of methanol as an organic solvent were mixed to produce a polymerizable monomer solution (organic 6 kg of the above aggregate was immersed in 100 parts by mass of the solvent and 36 parts by mass of the polymerizable monomer. After sufficiently stirring and confirming that the mixture became a slurry, the mixture was allowed to stand for 1 hour.
The above mixture was transferred to a rotary evaporator. While stirring, the mixture was dried for 1 hour under the conditions of a reduced pressure of 10 hectopascals and a heating condition of 40° C. (using a hot water bath) to remove the organic solvent. When the organic solvent was removed, a highly fluid powder was obtained.
The resulting powder was heated for 1 hour under a reduced pressure of 10 hectopascals and a heating condition of 100° C. (using an oil bath) with stirring with a rotary evaporator, whereby the polymerizable monomer in the powder was obtained. Was polymerized and cured. By this operation, 5.5 kg of a substantially spherical organic-inorganic composite filler (CF1) in which the surface of the spherical aggregate was covered with the organic polymer was obtained. The average particle size of this organic-inorganic composite filler was 33 μm.

2-3. Ultra fine particles (G-SFP)
As G-SFP, Reorosil QS-102 (average primary particle diameter 30 nm, manufactured by Tokuyama Corporation) was used.

3. Photopolymerization Initiator As the photopolymerization initiator, a photopolymerization initiator composed of a combination of camphorquinone (CQ), ethyl p-N,N-dimethylaminobenzoate (DMBE) and hydroquinone monomethyl ether (HQME) was used.

Example 1
Example 1 was manufactured according to the flow chart of the method for manufacturing the composite material in FIG. 1. Specifically, CQ: 4.8 g, DMBE: 16.0 g, and HQME: 2.4 g were added to and mixed with 1600 g of the polymerizable monomer mixture M1 to obtain a uniform polymerizable monomer composition. Was prepared. Next, G-PID 1:6400 g was measured, the above polymerizable monomer composition was gradually added under red light, and the capacity of the stirring container was 15 L. Planetary motion type stirrer planetary mixer (Inoue (Manufactured by Seisakusho) was used and kneading was performed for 2 hours at a rotating speed of the stirring blade of 7 to 10 rpm. After the kneading, the mixture was once stopped, 5.0 g of this mixture was sampled, decompression defoaming treatment was performed at a pressure of 1000 Pa for 5 minutes, and light was irradiated for 30 seconds with a visible light irradiator (TOKUYAMA, Powerlight) to cure the mixture. When the radial distribution function g(r) of the obtained cured product was examined, the position where the closest particle distance r ₁ was 0.88 times the particle diameter r ₀ (r ₁ /r ₀ was 0.88) , The first maximum peak of the radial distribution function g(r) was observed, and the minimum value of the radial distribution function g(r) between the next adjacent particle distance r ₂ was 0.32. The conditions 1 and 2 in the present invention were not satisfied. Then, after further kneading under the same conditions for 1 hour and sampling similarly, the radial distribution function g(r) of the cured product was examined, and it was confirmed that the conditions 1 and 2 were satisfied. Then, with respect to the cured product of the obtained polymerization-curable composition, the whole amount was recovered, (1) evaluation of the radial distribution function of the inorganic particles, (2) visual evaluation of colored light, and (3) evaluation of colored light. Wavelength measurement, (4) evaluation of color tone compatibility by a colorimeter, and (5) visual evaluation of color tone compatibility were performed. The composition of the cured product (composite material) (in the matrix column, the polymerizable monomer mixture that gives the resin to be the matrix is described) and the evaluation results are shown in Tables 3, 4 and 5. Further, as a reproducibility experiment, kneading was performed for 3 hours from the beginning with a planetary mixer, the whole amount was taken out, and the radial distribution function g(r) of the cured product was evaluated. The conditions 1 and 2 in the present invention were satisfied, It was confirmed that the desired structural color, which is the effect of the present invention, was developed. Under this mixing condition, it was confirmed that the prepared composite material of Example 1 satisfied the conditions 1 and 2 of the radial function g(r) with good reproducibility at a rate of 10 times out of 10 times, A uniform composition could be obtained with good reproducibility.
The above evaluations and measurements were carried out by the methods described below.

(1) Evaluation of Radial Distribution Function of Inorganic Particles The mixture (paste) was placed in a mold having a 5 mmφ×10 mm penetrating hole, and pressed on both sides with a polyester film. After irradiating both sides with a visible light irradiator (manufactured by Tokuyama, Power Light) for 30 seconds to cure, the composition was taken out of the mold to obtain a cured product (composite material) of the polymerization curable composition (paste). The dispersion state of the spherical particles in the cured product was observed by a scanning electron microscope ("XL-30S" manufactured by Philips) to obtain a radial distribution function and evaluated. Specifically, the cured product was subjected to cross-section milling with an ion milling device ("IM4000" manufactured by Hitachi, Ltd.) under the conditions of 2 kV and 20 min to obtain an observation plane. Thereafter, a microscope image of a region containing 1000 spherical particles in a plane is obtained on the observation surface by the scanning electron microscope, and the obtained scanning electron microscope image is subjected to image analysis software (“Simple Digitizer ver3. 2” free software) was used to determine the coordinates of the spherical particles within the region. From the obtained coordinate data, select one coordinate of an arbitrary spherical particle, draw a circle centered on the selected spherical particle and having a radius r at a distance r of at least 200 spherical particles, and include it within the circle. The number of spherical particles was determined, and the average particle density <ρ> (unit: particles/cm ² ) was calculated. dr _{is, r 0 / 100~r 0/10} (r 0 is. shows the average particle diameter of the spherical particles) is the value of the order, between the circle of the circle and the distance r + dr distance r from the spherical particles of the center The number dn of particles contained in the region and the area da of the region are determined. Using the values of <ρ>, dn, and da thus obtained, the following equation (2):
g(r) = {1/<ρ>}×{dn/da} (2)
Was calculated to obtain the radial distribution function g(r). A graph showing the relationship between the radial distribution function and r/r ₀ (r represents an arbitrary distance from the center of the circle and r ₀ represents the average particle diameter of spherical particles) was prepared and evaluated.

(2) Visual Evaluation of Colored Light The polymerization curable composition (paste) was put into a mold having a hole of 7 mmφ×1 mm penetrating, and pressed on both sides with a polyester film. Both sides were irradiated with light for 30 seconds with a visible light irradiator (Power Light, manufactured by Tokuyama Corporation) to cure, and then taken out from the mold to prepare an evaluation sample. The obtained evaluation material was placed on an adhesive surface of a black tape (carbon tape) of about 10 mm square, and the color tone of the colored light was visually confirmed.

(3) Wavelength of colored light The spectral reflectance of the evaluation material prepared in the same manner as in (2) was measured with a color difference meter (“TC-1800MKII” manufactured by Tokyo Denshoku) with a black background color and a white background color. Then, the maximum point of the reflectance in the background color black was set as the wavelength of the colored light.

(4) Evaluation of color tone compatibility using a colorimeter Using a hard resin tooth that reproduces a class I cavity (diameter 4 mm, depth 2 mm) at the center of the lower right 6th occlusal surface, the above-mentioned polymerization-curable composition is used at the defect. A simulated restoration was carried out by filling a material (paste), hardening and polishing. The color tone compatibility after the simulated restoration was evaluated by a two-dimensional colorimeter (“RC-500” manufactured by Paparabo Co., Ltd.). The hard resin teeth are in the A-type (red-brown) category of the shade guide (“VITAC Classic”, manufactured by VITA), and have a high-saturation hard resin tooth (corresponding to A4) and a low-saturation hard resin tooth. Within the category of B type (red-yellow) in the tooth (corresponding to A1) and the shade guide (“VITAC Classic”, manufactured by VITA), a hard resin tooth with high saturation (corresponding to B4) and a hard resin tooth with low saturation. (Corresponding to B1) was used.
The hard resin tooth is set on a two-dimensional colorimeter, the hard resin tooth is photographed, the photographed image is processed using image analysis software ("RC Series Image Viewer", manufactured by Paparabo Co., Ltd.), and the hard resin tooth is restored. The color difference (ΔE ^{* in} CIELab) between the calorimetric values of the non-restored area and the non-restored area was obtained, and the color tone compatibility was evaluated.
ΔE ^* ={(ΔL ^* ) ² +(Δa ^* ) ² +(Δb ^* ) ² } ^1/2
ΔL ^* =L1 ^* −L2 ^*
Δa ^* =a1 ^* -a2 ^*
Δb ^* =b1 ^* -b2 ^*
In addition, L1 ^* : lightness index of the restoration portion of the hard resin tooth, a1 ^* , b1 ^* : color index of the restoration portion of the hard resin tooth, L2 ^* : lightness index of the restoration portion of the hard resin tooth, a2 ^* , b2 ^* : Color quality index of the restoration part of the hard resin tooth, ΔE ^* : Color tone change amount.

(5) Visual evaluation of color tone compatibility Simulated restoration was performed in the same manner as in (4). The compatibility of the color tone after restoration was visually confirmed. The evaluation criteria are shown below.
5: The color tone of the restoration is indistinguishable from the hard resin teeth.
4: The color tone of the restoration matches well with the hard resin teeth.
3: The color tone of the restoration is similar to that of a hard resin tooth.
2: The color tone of the restoration is similar to that of the hard resin tooth, but the compatibility is not good.
1: The color tone of the restoration is not compatible with the hard resin teeth.

Example 2
In the same manner as in Example 1, Example 2 was manufactured according to the flowchart of the method for manufacturing the composite material in FIG. Specifically, CQ: 4.8 g, DMBE: 16.0 g, and HQME: 2.4 g were added to and mixed with 1600 g of the polymerizable monomer mixture M1 to obtain a uniform polymerizable monomer composition. Was prepared. Next, G-PID3: 3200 g, G-PID4: 3200 g, and ultrafine particle group (G-SFP): 8.0 g were weighed and the above polymerizable monomer composition was gradually added under red light. Then, using a planetary motion type agitator planetary mixer (manufactured by Inoue Seisakusho) in which the volume of the agitation vessel is 15 L, kneading was performed for 2 hours at a rotation speed of the agitation blade of 7 to 10 rpm. In the same manner as in Example 1, sampling evaluation was performed to determine the kneading time that satisfied the conditions 1 and 2 of the radial distribution function g(r), and the kneading time determined was kneaded. Regarding the obtained cured product of the polymerization curable composition, (1) evaluation of the radial distribution function of the inorganic particles, (2) visual evaluation of colored light, (3) wavelength measurement of colored light, (4) color The color tone compatibility was evaluated by a meter and (5) the color tone compatibility was visually evaluated. The evaluation results are shown in Tables 3, 4 and 5. Further, as a reproducibility experiment, kneading was performed from the beginning with a planetary mixer, the entire amount was taken out, and the radial distribution function g(r) of the cured product was evaluated. It was confirmed that the conditions 1 and 2 were satisfied and that the desired structural color was developed. It was confirmed that the composite material of Example 2 prepared under these mixing conditions satisfied the conditions 1 and 2 of the radial function g(r) with good reproducibility at a rate of 10 times out of 10. A uniform composition could be obtained with good reproducibility.

Example 3
In the same manner as in Example 1, Example 3 was manufactured according to the flowchart of the method for manufacturing the composite material in FIG. Specifically, CQ: 3.0 g, DMBE: 10.0 g and HQME: 1.5 g were added to and mixed with the polymerizable monomer mixture M1: 1000 g to obtain a uniform polymerizable monomer composition. Was prepared. Next, G-PID1:2000g, G-PID5:1000g, G-PID6:1000g, G-PID7:1000g and G-PID8:1000g were measured, and the above-mentioned polymerizable monomer composition under red light. The mixture was gradually added and kneaded for 2 hours at a rotation speed of stirring blades of 7 to 10 rpm using a planetary mixer (Planetary Mixer, manufactured by Inoue Seisakusho) having a capacity of 15 L for the stirring vessel. In the same manner as in Example 1, sampling evaluation was performed to determine the kneading time that satisfied the conditions 1 and 2 of the radial distribution function g(r), and the kneading time determined was kneaded. Regarding the obtained cured product of the polymerization curable composition, (1) evaluation of the radial distribution function of the inorganic particles, (2) visual evaluation of colored light, (3) wavelength measurement of colored light, (4) color The color tone compatibility was evaluated by a meter and (5) the color tone compatibility was visually evaluated. The evaluation results are shown in Tables 3, 4 and 5. Further, as a reproducibility experiment, kneading was carried out using a planetary mixer for a kneading time determined from the beginning, the whole amount was taken out, and the radial distribution function g(r) of the cured product was evaluated. The conditions 1 and 2 in the present invention were satisfied. Then, it was confirmed that the desired structural color, which is the effect of the present invention, was developed. Under these mixing conditions, it was confirmed that the composite material of Example 3 prepared satisfied the conditions 1 and 2 of the radial function g(r) with good reproducibility at a rate of 10 times out of 10. A uniform composition could be obtained with good reproducibility.

Example 4
In the same manner as in Example 1, Example 4 was manufactured according to the flowchart of the method for manufacturing the composite material in FIG. Specifically, CQ: 4.8 g, DMBE: 16.0 g, and HQME: 2.4 g were added to and mixed with 1600 g of the polymerizable monomer mixture M1 to obtain a uniform polymerizable monomer composition. Was prepared. Next, CF1:4800 g, G-PID4:1600 g, and ultrafine particle group (G-SFP): 16.0 g were weighed, and the polymerizable monomer composition was gradually added under red light. Using a planetary motion type agitator planetary mixer (manufactured by Inoue Seisakusho) having a stirring vessel capacity of 15 L, kneading was performed for 2 hours at a rotating speed of stirring blades of 7 to 10 rpm. In the same manner as in Example 1, sampling evaluation was performed to determine the kneading time that satisfied the conditions 1 and 2 of the radial distribution function g(r), and the kneading time determined was kneaded. Regarding the obtained cured product of the polymerization curable composition, (1) evaluation of the radial distribution function of the inorganic particles, (2) visual evaluation of colored light, (3) wavelength measurement of colored light, (4) color The color tone compatibility was evaluated by a meter and (5) the color tone compatibility was visually evaluated. The evaluation results are shown in Tables 3, 4 and 5. As a reproducibility experiment, kneading was carried out using a planetary mixer for a kneading time determined from the beginning, and the entire amount was taken out and evaluated for the radial distribution function g(r) of the cured product. The conditions 1 and 2 in the present invention were satisfied. Then, it was confirmed that the desired structural color, which is the effect of the present invention, was developed. Under this mixing condition, it was confirmed that the composite material of Example 4 prepared satisfied the conditions 1 and 2 of the radial function g(r) with good reproducibility at a rate of 10 out of 10. A uniform composition could be obtained with good reproducibility.

Comparative Example 1
CQ: 0.048 g, DMBE: 0.16 g and HQME: 0.024 g were added to and mixed with the polymerizable monomer mixture M 1: 16 g to prepare a uniform polymerizable monomer composition. Next, G-PID2: 64 g and ultrafine particle group (G-SFP): 0.08 g were weighed and the above polymerizable monomer composition was gradually added under red light, using a mortar. Hand kneading was carried out for 1 hour to prepare a curable paste. Further, this paste was subjected to reduced pressure defoaming treatment at a pressure of 1000 Pa to remove bubbles, and a polymerization-curable composition was produced. Regarding the obtained cured product (composite material) of the polymerization-curable composition, (2) visual evaluation of colored light, (3) wavelength measurement of colored light, (4) evaluation of color tone compatibility by colorimeter, (5) ) The color tone compatibility was visually evaluated. The composition of the cured product (composite material) (in the matrix column, the polymerizable monomer mixture that gives the resin to be the matrix is described) and the evaluation results are shown in Tables 3, 4 and 5. In the composite material of Comparative Example 1, good evaluation could not be obtained once in five times. With respect to this system, (1) the radial distribution function of the inorganic particles was evaluated. The evaluation results shown in the table are for this system.

As can be understood from the results of Examples 1 to 4, it is understood that the curable composition produced by satisfying the conditions defined in the present invention shows colored light with a black background and has good color tone compatibility. ..

As can be understood from the results shown in FIGS. 2 and 3, in the curable composition obtained in Example 1, the closest particle distance r ₁ was 1.03 times the particle diameter r ₀ (r ₁ /R ₀ is 1.03), the first maximum peak of the radial distribution function g(r) is observed, and the minimum value of the radial distribution function g(r) between the _second adjacent particle distance r ₂ Was confirmed to be 0.60, and it was confirmed to have the short-range ordered structure in the present invention.

As can be seen from the results shown in FIG. 4, in the curable composition obtained in Example 2, the closest interparticle distance r ₁ was 1.24 times the particle diameter r ₀ (r ₁ /r ₀ Is 1.24), the first maximum peak of the radial distribution function g(r) is observed, and the minimum value of the radial distribution function g(r) between the next adjacent interparticle distance r ₂ is 0. It was confirmed to be 62, and it was confirmed to have the short-range ordered structure in the present invention.

As can be understood from the results shown in FIG. 5, in the curable composition obtained in Example 3, the closest particle distance r ₁ was 1.41 times the particle diameter r ₀ (r ₁ /r ₀₎ Is 1.41), the first maximum peak of the radial distribution function g(r) is observed, and the minimum value of the radial distribution function g(r) between the next adjacent particle distance r ₂ is 0. It was confirmed to be 88, and it was confirmed to have the short-range ordered structure in the present invention.

As can be seen from the results shown in FIG. 6, in the curable composition obtained in Example 4, the closest interparticle distance r ₁ was 1.04 times the particle diameter r ₀ (r ₁ /r ₀ Is 1.04), the first maximum peak of the radial distribution function g(r) is observed, and the minimum value of the radial distribution function g(r) between the next adjacent interparticle distance r ₂ is 0. It was confirmed to be 80, and it was confirmed to have the short-range ordered structure in the present invention.

As can be understood from the results of Comparative Example 1, when the kneaded state of the composition becomes non-uniform, the condition of the arrangement structure of the inorganic spherical particles defined in the present invention is not satisfied, and the color tone compatibility with the tooth substance is satisfied. It turns out that it is inferior to.

As understood from the results shown in FIG. 7, the curable composition obtained in Comparative Example 1 is the closest distance between particles r ₁ is 1.58 times the particle diameter r ₀ position (r 1 _/ r ₀ Is 1.58), the first maximum peak of the radial distribution function g(r) is observed, and the minimum value of the radial distribution function g(r) between the _second adjacent particle distance r ₂ is 0. It was confirmed that it was 18, and it was confirmed that it did not have the short-range ordered structure in the present invention.

That is, the present invention provides polymerizable monomer (A), no aircraft particles (B), and comprises a photopolymerization initiator (C) as a constituent component, and a cured body which develops a structural color of a predetermined color A method for producing a polymerization-curable composition, comprising:
The inorganic particles (B) are
(I) It is composed of an aggregate of inorganic spherical particles having a predetermined average primary particle diameter within the range of 100 to 1000 nm, and the individual inorganic spherical particles constituting the aggregate are composed of substantially the same substance. At the same time, in the number-based particle size distribution of the aggregate, 90% or more of the total number of particles is present within a range of 5% before and after the predetermined average primary particle size, and one or a plurality of “spherical particle groups with the same particle size (Group)”. of spherical Particle having Dental Diameter” (G-PID),
(Ii) When the number of the one or more "spherical particle groups having the same particle size" is a, the "spherical particle groups having the same particle size" are respectively G-PID _m (provided that the average primary particle size is smaller). , M is 1 when a is 1, and is a natural number from 1 to a when a is 2 or more.), each G-PID _m when a is 2 or more May be different from each other, and the average primary particle diameter of each G-PID _m in that case is different from each other by 25 nm or more, and
(Iii) a refractive index at 25 ° C. of the polymerizable monomer cured product of components (A) and _{n (MX),} the refractive index at 25 ° C. of the inorganic spherical particles constituting the respective G-PID _{m n ( G-PIDm)} , for any n _(G-PIDm) ,
n _(MX) <n _(G-PIDm)
Satisfy all the conditions that the relationship of
The method includes a mixing step of mixing the polymerizable monomer (A), the inorganic particles (B) and the photopolymerization initiator (C),
Wherein the mixing step,
For a cured product of a mixture containing the polymerizable monomer (A), the inorganic particles (B) and the photopolymerization initiator (C), a distance r from the center of any inorganic spherical particle dispersed in the cured product. A radial distribution function g(r) representing the probability that other inorganic spherical particles exist at a distant point is determined based on a scanning electron microscope image in which the surface inside the cured body is an observation plane. Average particle density of the inorganic spherical particles in the observation plane: <ρ>, inorganic spherical particles present in a region between the circle of distance r and the circle of distance r+dr from any inorganic spherical particle in the observation plane Based on the number of dn and the area of the region: da (provided that da=2πr·dr).
Formula: g(r)={1/<ρ>}×{dn/da}
When expressed by
(1) Separately in advance, a composition having the same or substantially the same composition as the polymerization-curable composition to be actually produced was used, the mixing conditions were changed plural times, and the mixture was mixed under each mixing condition. By examining the radial distribution function: g(r) in the cured product of the mixture obtained at this time, the dispersion state of the inorganic particles (B) in the cured product of the above composition was determined by the following conditions (I) and ( II) is determined, and the polymerizable monomer (A), the inorganic particles (B) and the photopolymerization initiator (C) are mixed under the same mixing conditions as the determined mixing conditions. Or
(2) A part of the mixture obtained during and/or after the mixing step is sampled, and the dispersion state of the inorganic particles (B) in the cured product of the sampled mixture has the following conditions (I) and ( II) is confirmed, and if these conditions are not satisfied, the mixing is continued until these conditions are satisfied.
The mixing step after the end of the resulting mixture, the dispersion state of the inorganic particles in the cured product in (B) is to satisfy the following condition (I) and (II),
The method is characterized by the above.
[ Conditions that the dispersed state must satisfy]
Distance from the center of any inorganic spherical particles dispersed in (I) the hard embodying: r the average of the entire inorganic spherical particles having a particle diameter dispersed in the hard embodying: at r _0, divided by standard It phased dimensionless number (r / _{r 0)} and x-axis, the dynamic radial distribution function: g a (r) as the y-axis, the r / _{r 0} and the the g (r) corresponding to r at that time In the radial distribution function graph showing the relationship, among the peaks appearing in the radial distribution function graph, the closest interparticle distance: r ₁ defined as r corresponding to the peak top of the peak closest to the origin is Average particle diameter of the whole inorganic spherical particles dispersed in the cured product of the mixture: a _value of 1 time or more and 2 times or less of r ₀ .
(II) Of the peaks appearing in the radial distribution function graph, when r corresponding to the peak top of the second peak closest to the origin is set as the next adjacent particle distance: r ₂ , the closest particle distance: The minimum value of the radial distribution function: g(r) between r ₁ and the distance between adjacent particles: r ₂ is 0.56 or more and 1.10.

Claims (4)

A polymerizable monomer (A), inorganic particles (B) satisfying the following conditions (i), (ii) and (iii), and a photopolymerization initiator (C) are contained as constituent components and have a predetermined color tone. A method for producing a polymerization-curable composition that gives a cured product that develops a structural color,
The method includes a mixing step of mixing the polymerizable monomer (A), the inorganic particles (B) and the photopolymerization initiator (C),
In the mixing step, the dispersion state of the inorganic particles (B) in the cured product obtained by curing the mixture obtained in the step may satisfy the following conditions (I) and (II). The mixing is performed by using the confirmed mixing conditions,
The method as described above.
[Conditions that the inorganic particles (B) must satisfy]
(I) It is composed of an aggregate of inorganic spherical particles having a predetermined average primary particle diameter within the range of 100 to 1000 nm, and the individual inorganic spherical particles constituting the aggregate are composed of substantially the same substance. At the same time, in the number-based particle size distribution of the aggregate, 90% or more of the total number of particles is present within a range of 5% before and after the predetermined average primary particle size, and one or more "spherical particle groups having the same particle size" ( G-PID).
(Ii) When the number of the one or more "spherical particle groups having the same particle size" is a, the "spherical particle groups having the same particle size" are respectively G-PID _m (however, in the order of decreasing average primary particle size). , M is 1 when a is 1, and is a natural number from 1 to a when a is 2 or more.), each G-PID _m when a is 2 or more individual or different particles together material constituting the average primary particle diameter of each G-PID _m when the are different from each 25nm or more from each other.
(Iii) a refractive index at 25 ° C. of the polymerizable monomer cured product of components (A) and _{n (MX),} the refractive index at 25 ° C. of the inorganic spherical particles constituting the respective G-PID _{m n ( G-PIDm)} , for any n _(G-PIDm) ,
n _(MX) <n _(G-PIDm)
The relationship is established.
[Conditions that the dispersed state must satisfy]
(I) The distance from the center of any inorganic spherical particles dispersed in the cured product of the mixture: r is divided by the average particle diameter of the entire inorganic spherical particles dispersed in the cured product of the mixture: r _0. A radial distribution function that represents the probability that another inorganic spherical particle exists at a point separated by a distance r from the center of the arbitrary inorganic spherical particle, where x is a dimensionless number (r/r ₀ ) standardized by In the radial distribution function graph showing the relationship between the r/r ₀ and the g(r) corresponding to r at that time with (r) as the y-axis, among the peaks appearing in the radial distribution function graph, The closest particle distance: r ₁ defined as r corresponding to the peak top of the peak closest to the origin is 1 or more times the average particle size of all inorganic spherical particles dispersed in the cured product of the mixture: r ₀ It is a value of 2 times or less.
(II) Of the peaks appearing in the radial distribution function graph, when r corresponding to the peak top of the second peak closest to the origin is set as the next adjacent particle distance: r ₂ , the closest particle distance: The minimum value of the radial distribution function: g(r) between r ₁ and the distance between adjacent particles: r ₂ is 0.56 or more and 1.10. The radial distribution function: g(r) is determined based on a scanning electron microscope image in which the inner surface of the cured body of the mixture is used as an observation plane, and the average particle of the inorganic spherical particles in the observation plane. Density: <ρ>, and the number of inorganic spherical particles present in a region between a circle of distance r and a circle of distance r+dr from any inorganic spherical particle in the observation plane: dn, and area of the region : Da (however, da=2πr·dr) based on the following formula (1):
g(r)={1/<ρ>}×{dn/da} (1)
The method of claim 1, calculated by: The method of determining the mixing conditions adopted in the mixing step,
(1) Separately in advance, a composition having the same or substantially the same composition as the polymerization-curable composition to be actually produced was used, the mixing conditions were changed plural times, and the mixture was mixed under each mixing condition. Mixing conditions satisfying the above conditions (I) and (II) are determined by examining the radial distribution function: g(r) in the cured product of the mixture obtained at this time, and the determined mixture is determined. Or (2) a part of the mixture obtained during and/or after the mixing step is sampled and the inorganic substance in the cured product of the sampled mixture is used. It is a method of confirming whether the dispersed state of the particles (B) satisfies the above conditions (I) and (II), and continuing the mixing until these conditions are satisfied,
The method according to claim 1 or 2. The polymerization-curable composition is composed of inorganic particles having an average primary particle diameter of less than 100 nm as the inorganic particles (B), and the average primary particle diameter is 25 nm or more smaller than the average primary particle diameter of the G-PID _1. Method according to any of claims 1 to 3, characterized in that it further comprises a group of ultrafine particles" (G-SFP).