JP6154454B2 - Method for producing opal composite material - Google Patents

Description

  The present invention relates to an opal composite material and a method for producing the same.

  Natural opal is an aggregate of colloidal particles of silica and is collected as a bulk ore.

  On the other hand, opal is also manufactured artificially. For example, colloidal particles of silica are dispersed in a polymerizable substance and then polymerized to polymerize the colloidal particles to form an opal. It is known (see, for example, Patent Document 1).

International Publication No. 2003/100139 Pamphlet

  However, the opal as described above has a resin impregnated in an aggregate made of silica particles as shown in FIG. Therefore, as shown in FIG. 3 and FIG. 4, the main surface 3 of the assembly 20 faces one direction, so that the main surface 3 changes to a constant color such as red to yellow to green to blue depending on the angle of the viewpoint. In some cases, it was impossible to visually recognize various colors from various directions.

  In addition, since the opal has low bending strength, it may be difficult to flexibly paste it on the curved surface. Further, since it takes time to precipitate the silica particles 1, it may be difficult to obtain an opal having a predetermined thickness.

  An object of the present invention is to provide an opal composite material that has an excellent play-coloring effect capable of visually recognizing a variety of colors regardless of the angle of the viewpoint and is easy to process.

In one embodiment of the present invention, a method for producing an opal composite material includes a precursor forming step of mixing a silica particle with a dispersion medium to produce a dispersion, and forming a sheet-like precursor, and drying the precursor. The thin film opal forming step of evaporating the dispersion medium to form a thin film opal, and by pulverizing the thin film opal, the silica particles having an average particle diameter of 200 to 400 nm are agglomerated, and Aggregate formation step of obtaining a plurality of aggregates, each having a principal surface serving as a Bragg diffraction surface in which silica particles are regularly arranged and having a major axis of the major surface of 50 to 2000 μm, and a plurality of the aggregates A dispersion step of dispersing the body in the first resin, and a solidification step of solidifying the first resin in which the plurality of aggregates are dispersed to obtain a solidified product.

  According to the opal composite material of the present invention, the Bragg diffraction surface in the opal composite material can easily be oriented in various directions. Therefore, the angle of the viewpoint with respect to the opal composite material and the orientation of silica particles in the aggregate in the opal composite material A stable play color effect can be visually recognized with high luminance without being affected by anisotropy.

  Moreover, according to the manufacturing method of the opal composite material of this invention, the opal composite material which expanded the workability and the freedom degree of an application can be obtained efficiently.

It is a schematic diagram of the opal composite material of this embodiment. It is a drawing substitute photograph which shows the state of the aggregate according to each silica particle diameter of the opal composite material of this embodiment. It is a schematic diagram of the conventional opal. 4 is a drawing-substituting photograph of the main surface of the conventional opal of FIG. 3. It is a schematic diagram in other embodiment of the opal composite material of this embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(Opal composite material)
The opal composite material of the present embodiment is an opal composite material that includes a plurality of aggregates composed of a plurality of silica particles in the first resin, and the aggregate has a main surface serving as a Bragg diffraction surface.

  In FIG. 1, the silica particles 1 are colloidal particles of silica, and the aggregates 2 are formed by aggregation of the silica particles 1.

  The assembly 2 has a main surface 3 that becomes a Bragg diffraction surface. On the main surface 3, the silica particles 1 are regularly arranged. The diffracted light 5 b, which is Bragg diffracted through the optical path 5 through this regular arrangement, has a play-color effect. For example, the major surface 3 has an average major axis of 50 to 2000 μm.

  The assembly 2 only needs to have at least one main surface as described above, and the shape thereof is not particularly limited.

  In FIG. 1, the optical path 5 is illustrated only from one direction, but light is actually incident from all directions.

  The arrangement of the silica particles 1 on the main surface 3 only needs to be regular enough to cause Bragg diffraction in the optical path 5, and the silica particles 1 may partly fall off.

  Further, the structure of the silica particles 1 on the main surface 3 may be anything as long as it can generate the Bragg diffraction of the optical path 5, and may be other than the arrangement structure shown in FIG. Examples of the array structure include a cubic structure, a tetragonal structure, and a hexagonal close-packed structure.

  The aggregate 2 includes, for example, a pulverized product of opal, and the shape thereof may be a polyhedron, particularly a plate-like body that can enlarge the main surface. In the case of this plate-like body, for example, the front surface and the back surface can be used as the main surface.

A plurality of aggregates 2 are dispersed in the first resin 4 a to form an opal composite material 10. As described above, when the main surface 3 faces in various directions in the first resin, the play color effect of various hues is obtained by the reflected light 5a on the main surface 3.

  FIG. 2 is an electron micrograph of the opal composite material 10 including the aggregate 2 obtained for each average particle diameter of the silica particles 1. The portion that appears white in FIG. 2 is the assembly 2, and the portion that appears black is resin. Thus, it can be seen that the aggregate 2 is dispersed in the resin.

  The main surfaces 3 of these assemblies 2 are preferably oriented in different directions. For example, the assembly has a first assembly having a main surface facing one direction and a direction different from the one direction. It is preferable to have at least a second assembly having a main surface facing.

  Specifically, the optical paths 5 incident on the three aggregates 2 shown in FIG. 1 from the same direction are reflected in different directions and Bragg diffracted in different directions.

  Thereby, the play-color effect having a plurality of hues can be obtained with a constant luminance without depending on the angle of the viewpoint of viewing the surface of the opal composite material 10.

  Here, it is stable that at least one of the main surfaces 3 is a cleavage plane without being affected by color unevenness due to the different orientation of the silica particles 1 between the main surface 3 and the side surfaces of the aggregate 2. It is preferable in that it has a variety of playful color effects, and more preferably, the arithmetic average surface roughness of the main surface 3 of the aggregate 2 is 400 nmRa or less in view of exhibiting high luminance and playful color effects.

  Furthermore, according to this embodiment, it is preferable that the average particle diameter of a silica particle is 200-400 nm.

  In this range, if the silica particles 1 are small, blue color development will be strong, and if the silica particles 1 are large, red color development will be strong. In particular, it is preferable that a plurality of aggregates 2 of silica particles 1 having different average particle diameters exist. For example, the aggregate 2 of silica particles 1 having an average particle diameter of 200 nm is visually recognized in blue, the aggregate 2 of silica particles 1 having an average particle diameter of 300 nm is visually recognized as yellow-green, and the silica particles 1 having an average particle diameter of 400 nm. The assembly 2 is visually recognized in red. When the aggregate 2 of the three types of silica particles 1 having different average particle diameters is contained in the opal composite material 10, a further play-off effect is exhibited.

  In the case where there are a plurality of aggregates 2 of silica particles 1 having different average particle diameters, for example, the difference in average particle diameter between the first aggregate and the second aggregate is preferably 100 nm or more. Thus, when there is a difference in average particle diameter, the contrast becomes higher. When three or more aggregates 2 are included, if the difference in average particle diameter between a group of a certain aggregate 2 (first aggregate group) and the remaining aggregate 2 group (second aggregate group) is 100 nm or more Good. For example, when the average particle diameter of the first aggregate group is 200 nm and the average particle diameter of the second aggregate group is 300 nm, the contrast is further improved if the average particle diameter of the third aggregate group is 400 nm. It tends to be expensive.

  Furthermore, according to this embodiment, it is preferable that the average length of the major axis of the main surface of the aggregate is 50 to 2000 μm.

  This is preferable in that the aggregate 2 is easy to disperse and hardly aggregate.

  Here, the distance between the aggregates 2 is preferably 20 to 2000 μm from the viewpoint of efficiently exhibiting the play-color effect in that the aggregates 2 do not overlap with each other. Can be controlled by electrostatic repulsion.

  Furthermore, according to the present embodiment, the first resin is an epoxy resin or an acrylic resin.

  The first resin 4a is not particularly limited as long as the aggregate 2 of the contained silica particles 1 can be visually recognized. For example, an epoxy resin, an acrylic resin, a vinyl chloride resin, etc. are mentioned. From the viewpoint of uniformly dispersing and fixing the aggregate 2 of the silica particles 1, an epoxy resin or an acrylic resin is preferable. In particular, the epoxy resin tends to have a large refractive index difference from the aggregate 2 of the silica particles 1 and exhibits an excellent color-playing effect.

  Here, the refractive index of the first resin 4a is preferably 1.05 to 2.00 in terms of improving hue and luminance.

Furthermore, according to this embodiment, the ratio between the aggregate and the first resin is from 3: 7 to 7: 3 in terms of mass ratio.
It is.

  Thereby, in the sheet-like opal composite material 10, the bending strength can be improved without impairing the play effect, and the opal composite material 10 can be easily attached to various curved surfaces. As other inclusions, the first resin 4a may contain a pigment for coloring, or the aggregate 2 may be impregnated with a different kind of resin.

  Although the bending strength depends on the thickness and material of the opal composite material 10, if the thickness is 0.5 to 2 mm when processed into a sheet shape, sufficient bending strength and flexibility can be satisfied.

(Production method)
The manufacturing method of the opal composite material of the present embodiment includes a first step of obtaining a plurality of aggregates by pulverizing a thin film-like opal, and a second step of dispersing the plurality of aggregates in the first resin. And a third step of solidifying the first resin in which the aggregates are dispersed to obtain a solidified product.

  In the first step, the thin film-like opal is pulverized to obtain a plurality of aggregates 2.

  First, the silica particles 1 are mixed little by little with the dispersion medium, and finally, the dispersion medium is stirred for 1 to 3 minutes so that the dispersion medium is about 1 to 5 times the silica particles 1 by mass ratio.

  The dispersion medium is not particularly limited as long as it is a liquid having polarity. For example, water, alcohol, a mixture thereof and the like can be mentioned. A highly polar liquid such as water is particularly preferable, and a highly volatile liquid such as alcohol can be used as the dispersion medium.

  Next, the dispersion liquid of the silica particles 1 is put in a burette and coated on a flat plate to form a sheet-like opal precursor. Here, it is preferable that the flat plate is hydrophilic.

  Next, the precursor on the flat plate is moved to the drying chamber so as not to break down, and the dispersion medium of the dispersion of silica particles 1 is gradually evaporated, so that the silica particles 1 precipitate and the silica particles 1 aggregate. Furthermore, it is preferable that the dispersion medium of the dispersion of silica particles 1 is gradually evaporated. The drying temperature and time may satisfy the time required for the silica particles 1 to precipitate and the silica particles 1 to aggregate, and are approximately 30 to 40 ° C. and 1 to 10 minutes.

Next, the aggregate 2 is obtained by a pulverization method such as rubbing the dried thin film-shaped opal with a rim bar from a flat plate. Alternatively, the aggregate 2 may be obtained by washing the thin film-like opal with a dispersion medium such as water or alcohol and filtering to separate the dispersion medium and the silica particles 1. Alternatively, a thin film-like opal may be put into the mill.

  Thus, if the thin film-like opal is pulverized, the aggregate 2 having a major surface can be obtained.

  In addition, by adding and impregnating a resin in advance to the opal on the thin film formed on the flat plate, when the rim bar or the like is rubbed off, the aggregate 2 is broken and the main surface 3 is damaged. be able to.

  As a result, the assembly 2 can be stably manufactured with good reproducibility and efficiency, and thus mass production is possible.

  The thin film-shaped opal impregnated with the resin can maintain the main surface 3 without losing the plate shape even in the subsequent pulverization.

  In addition, when the thin film-like opal not impregnated with resin is pulverized, the aggregate 2 is likely to have an indefinite shape, but it is sufficient that the main surface 3 serving as a Bragg diffraction surface is mostly included. If there is a main surface 3 in the relationship, it is more preferable.

  When the aggregate 2 that is not impregnated with resin is included in the opal composite material 10, a play-coloring effect having more various colors can be obtained.

  Such a pulverized aggregate 2 may be classified so that the particle diameters are uniform. As a classification method, since the aggregates 2 stick to each other when filtered with a filter, it is preferable to classify the dispersion in which the aggregates 2 are dispersed in water by centrifugation and then store them in a stirred dispersion medium. .

  In the second step and the third step, the plurality of aggregates 2 are dispersed in the first resin 4 to solidify the first resin 4a.

  In the dispersion step, when the two are not mixed due to the difference in specific gravity between the aggregate 2 and the first resin 4a, the aggregate 2 is dispersed or further heated gradually while the first resin 4a is stirred or convected. Thus, the first resin 4a may be solidified.

  By such a dispersion step, the opal composite material 10 in which the Bragg diffraction surfaces of the aggregates 2 face in different directions can be obtained.

  The obtained opal composite material may use buffing as the final surface finish, but the presence or absence of polishing and the type of polishing are not limited thereto. Alternatively, the surface can be smoothed by applying varnish or the like without polishing.

  The opal composite material 10 can be used for decoration such as wallpaper, wrapping paper, packaging, or a raft pattern of crafts by slicing with a wire saw or the like to form a sheet. .

  Moreover, such an opal composite material 10 can be utilized not only in a sheet form but also in a bulk state, and various cut shapes such as jewelry can be easily realized.

  Further, such an opal composite material 10 can be used for large materials such as building materials.

  Furthermore, according to the present embodiment, in the second step, the aggregates are ultrasonically vibrated in the first resin, so that the aggregates are electrostatically repelled and dispersed.

  As a result, electrostatic repulsion can be performed and uniform dispersion can be achieved, so that the overlapping of the aggregates 2 can be reduced.

  For example, before solidifying the first resin 4a, the mixture containing the first resin 4a and the aggregate 2 is treated with an ultrasonic cleaning machine, and the aggregates 2 are rubbed with each other to be charged with static electricity. Thus, the aggregates 2 can be charged so as to repel each other.

  When the mixture of the first resin 4a and the assembly 2 is charged by an ultrasonic cleaner, the concentration of the assembly 2 in the mixture including the first resin 4a and the assembly 2 is finally used. If the concentration is higher than the concentration of the assembly 2 at the time, the assembly 2 can be charged efficiently.

  This final concentration adjustment may be performed by additionally adding the first resin 4a separately.

  Here, when the first resin 4a is added, the potential of the mixture of the first resin 4a and the aggregate 2 and the potential of the first resin 4a to be added are prevented so that the charge of the aggregate 2 is not removed. It is necessary to match with.

  Furthermore, according to this embodiment, the 4th process of obtaining a granular material by grind | pulverizing the solidified material obtained in the 3rd process, the 5th process of disperse | distributing a granular material in 2nd resin, and a granular material And a sixth step of solidifying the second resin in which is dispersed.

  Thereby, in the opal composite material 10, it is possible to obtain a high density region of the aggregate 2 and a low density region of the aggregate 2.

  For example, in FIG. 5, the aggregate 2 in the resin preferably has a density at the surface portion 8 of the opal composite material 10 higher than the density at the center portion 7 of the opal composite material 10.

  In the surface portion 8 of the opal composite material 10, there are many regions (granular bodies 6) indicated by dotted circles in FIG. 5, and the proportion of the granular bodies 6 (aggregates 2) is relatively large, and thus a high-density region. .

  That is, the aggregate 2 is biased near the surface portion 8 of the opal composite material 10 to form a high density region, and the aggregate 2 near the center portion 7 of the opal composite material 10 that does not contribute to the play color effect is reduced to a low density region. Thus, even when the thickness of the entire opal composite material 10 is increased, a decrease in light transmittance in the entire opal composite material 10 can be suppressed, and the luminance can be maintained high.

  Specifically, it is obtained by the following method.

  First, after solidifying the 1st resin 4a, this is grind | pulverized with a mill etc. until it becomes the granular material 6 with a particle size of about 1-10 mm, for example.

  And the granular material 6 will be in the state which floated in the 2nd resin 4b by mixing this granular material 6 and the newly added 2nd resin 4b anew.

By solidifying this, a high-density region of the aggregate 2 and a low-density region of the aggregate 2 as shown by dotted lines in FIG. 5 can be obtained.

  Here, the first resin 4a solidified first and the second resin 4b additionally solidified later may be the same, but resins having different refractive indexes (for example, epoxy resin and acrylic resin, respectively) Etc.) is preferable in that the contrast between the high density region and the low density region of the aggregate 2 can be further increased.

  In addition, by preparing the granular material 6 having a different specific gravity of the first resin 4a, the granular material 6 can be precipitated or suspended in the second resin 4b, and the granular material is formed on the surface portion 8 of the opal composite material 10. 6 (aggregate 2) can be biased, and further, it can be promoted that the granule 6 (aggregate 2) is biased to the surface portion 8 of the opal composite material 10 by centrifugal separation.

  Alternatively, the opal composite material 10 having a low density of the aggregate 2 may be simply sandwiched and bonded by the opal composite material 10 having a high density of the aggregate 2.

  Furthermore, according to the present embodiment, in the fifth step, it is preferable to disperse the particles by electrostatically repelling them by ultrasonically vibrating the particles in the second resin.

  This is preferable in that electrostatic repulsion between the granular bodies 6 can be facilitated, and the contrast between the high density region and the low density region of the aggregate 2 can be further increased.

  Hereinafter, sample preparation of the opal composite material according to the example and the comparative example will be described.

<Example 1>
(Sample preparation)
Sample numbers 1 to 19 were prepared as follows.

  First, silica particles 1 having an average particle diameter of 100, 200, 300, 400, and 500 nm are prepared, and finally the dispersion medium is about three times as much as silica particles 1 in mass ratio while being mixed with water in small amounts. The slurry was stirred for 1 hour to prepare a slurry-like dispersion of silica particles 1.

  Next, a dispersion of the slurry-like silica particles 1 was applied on a flat plate with a thickness of 2 mm using a roll coater to form a sheet-like opal precursor. Here, a hydrophilic sheet was used for the flat plate.

  Next, the opal precursor on the flat plate is moved to the drying chamber so as not to break, and is left in the atmosphere at a temperature of 80 ° C. and a humidity of 30%, and the precursor (slurry silica particles 1) The dispersion medium was gradually evaporated to precipitate the silica particles 1, and the silica particles 1 were aggregated.

  Next, the aggregate 2 of the dried silica particles 1 is scraped off from the flat plate with a rim bar, and this is sieved, so that the average major axis length of the aggregate 2 is 50, 100, 500, 1000, 2000, 3000 μm, respectively. I prepared something.

  In this case, as a method of sieving, a method in which the aggregate 2 was dispersed in water and classified by a centrifugal separation method was used.

  The assembly 2 is dispersed in a two-component epoxy resin while stirring at a mass ratio of 2: 8 to 8: 2, and heated at 130 ° C. for 3 hours with vacuum degassing to opal composite material 10. Got.

This was cut out with a wire saw at a thickness of 1 mm and 10 cm square, and each cut out sample was buffed to give a glossy surface, and each sample was prepared one by one.
It was set as the sample for evaluation.

  For sample number 20 as a comparative example, the colloidal particles were regularly arranged in the epoxy resin by dispersing the silica colloidal particles containing the epoxy resin of Patent Document 1 and then polymerizing the epoxy resin. Using opal, it was cut out with a thickness of 1 mm and a 10 cm square, and the surface was further processed by buffing to prepare a glossy surface.

(Sample evaluation)
As for the evaluation method of the play color effect (including luminance), 10 evaluators were arbitrarily selected and observed with respect to the surface of the opal composite material 10 while visually changing the angle of the viewpoint.

  And compared with the sample number 20 which is a comparative example, it was set as (circle) if the play color effect (a brightness | luminance is included) was excellent, (triangle | delta), if equivalent, and x.

  The evaluation results of the play-color effect of the opal composite material 10 are shown in Table 1 below.

  In Table 1, Sample Nos. 1 to 19 are examples, Sample No. 20 is a comparative example, and Sample Nos. 3, 9, and 16 are samples under the optimum conditions of the present example manufactured under the same conditions.

  Sample Nos. 1 to 5 were obtained by changing the condition of the average particle size, and exhibited an excellent play-color effect at an average particle size of 200 to 400 nm.

  This is because the opal composite material 10 was easy to visually recognize red to yellow to green to blue at the same time.

  In Sample Nos. 6 to 12, the long axis length conditions were changed, and an excellent play effect was exhibited at the long axis length of 50 to 2000 μm.

  This is because the size of the spots (the size of the aggregate 2) of the opal composite material 10 is made visible, and it is easy to exhibit various shades per unit area.

  In Sample Nos. 13 to 19, the mass ratio between the aggregate 2 and the resin 4 was changed in the range of 2: 8 to 8: 2, and an excellent play effect was exhibited. More preferably, in the range of 3: 7 to 7: 3, the opal composite material 10 exhibited an excellent color play effect.

  In addition, the larger the mass ratio of the first resin 4a, the more satisfied the workability and bending strength of the opal composite material 10.

  On the other hand, the sample 20 was cracked during processing and could not withstand the evaluation in the first place. Met.

  In the present embodiment, the description is based on the result of using an epoxy resin as the first resin 4a. However, even when an acrylic resin is used, the same play effect (including luminance) is obtained. Because it is, it is omitted.

<Example 2>
(Sample preparation)
For Sample Nos. 21 to 25, the solidified material produced based on Sample No. 3 in Example 1 was once pulverized into granules (average particle size of about 5 mm) with a mill or the like to obtain Granules 6.

  The granular body 6 and the second resin 4b were mixed, the granular body 6 was ultrasonically vibrated in the second resin 4b, and the granular bodies 6 were electrostatically repelled and dispersed.

  The opal composite material 10 is produced by changing the mass ratio of the aggregate 2 and the second resin 4b so that the area ratio of the aggregate 2 when viewed in cross section is as shown in Table 2. The plate-like body for the central portion 7 and the plate-like body for the surface portion 8 are each made 100 × 100 × 10 mm, and bonded and combined on the main surface of each plate-like body, as shown in FIG. An opal composite material 10 having a proper distribution was obtained.

(Sample evaluation)
The evaluation method of the play color effect (including luminance) was performed in the same manner as in Example 1.

  About the evaluation method of background brightness, 10 evaluators were arbitrarily selected and observed with respect to the surface of the opal composite material 10 while visually changing the angle of the viewpoint.

  And compared with the sample numbers 3, 9, and 16 of Example 1, it was set as (circle) if the brightness of a background was excellent, (triangle | delta), if it was inferior, and x if it was inferior.

  Hereinafter, Table 2 shows the evaluation results of the play color effect and background brightness of the opal composite material 10.

  In Table 2, Sample Nos. 21 and 22 exhibited excellent background brightness and excellent play-color effect.

This is because the density of the aggregate 2 in the central portion 7 of the opal composite material 10 is low and the density of the aggregate 2 in the surface portion 8 is high, and thus the light transmittance is excellent.

1: Silica particle 2: Aggregate 3: Main surface 4a: First resin 4b: Second resin 5: Optical path 5a: Reflected light 5b: Diffracted light 6: Granular body 7: Center part 8: Surface part 10: Opal Composite material 20: aggregate

Claims (3)

An opal composite material manufacturing method comprising:
A precursor forming step of mixing a silica particle with a dispersion medium to prepare a dispersion and forming a sheet-like precursor;
A thin film-shaped opal forming step of drying the precursor and evaporating the dispersion medium to form a thin film-shaped opal;
By pulverizing the thin film-like opal, silica particles having an average particle diameter of 200 to 400 nm are aggregated, and a main surface serving as a Bragg diffraction surface in which the silica particles are regularly arranged is provided. An assembly forming step of obtaining a plurality of assemblies having an average length of the major axis of the surface of 50 to 2000 μm;
A dispersion step of dispersing a plurality of the aggregates in the first resin;
And a solidifying step of solidifying the first resin in which a plurality of aggregates are dispersed to obtain a solidified product. 2. The method for producing an opal composite material according to claim 1, wherein, in the aggregate formation step, the thin film opal is pulverized after the thin film opal is impregnated with a resin. In the dispersion step, the aggregates are ultrasonically vibrated in the first resin to disperse the aggregates by electrostatic repulsion.
The manufacturing method of the opal composite material of Claim 1 or 2 .