AU784970B2 - Artificial stone and formation therefor - Google Patents

Description

ARTIFICIAL STONE AND FORMATION THEREFOR Technical Field The present invention relates to an artificial stone and its formation. More particularly, the present invention relates to a noctilucent and/or luminescent artificial stone which is useful for a building material, a view material, or the like such as a direction indicator, or a location guide with a decorative or a dark-field illumination taking advantage of the luminosity with an accumulation of light or an absorption ~of ultraviolet rays, and its formation.

9 4 Background Art Anartificial stone caked froma mixture of acrushednatural S 15 stone with a resin or the like is conventionally known.

Various ideas ha" been carried out to make this artificial stone 0% 0 •:go have a design of a natural stone style such as marble or granite and besides superior hardness and strength.

o o *oo. As a trial for improving a function and performance of such 20 an artificial stone, it is proposed to give a luminosity function to the artificial stone with using a luminescent substance such as a noctilucent substance like a light accumulation material or an ultraviolet ray luminescent material emitting light with ultraviolet rays absorption.

For instance, a luminescent tile which consists of an inorganic filler, a synthetic resin, and a light accumulation pigment and includes an inorganic filler of more than about 50 of the total amount, is proposed (Japanese Patent Laid-Open No.

60-137862). For instance, on this luminescent tile, a board of 3 to 5mm thick is proposed, which is molded and hardened from a composition of; 75 wt% of silica sand as an inorganic filler with an average particle diameter of 0.2 mm or more, 15 wt% of syrup consisting of MMA polymer/MMA monomer of 25/75 in a weight ratio, and 9 wt% of a light accumulation pigment.

In addition, a luminescent material obtained from the following composition is proposed; a natural or synthesized luminescent stone emitting light by ultraviolet rays and an adhesive resin of 4 to 10 wt% against a total amount along with a natural or synthesized aggregate (Japanese Patent Laid-Open No. 8-1197068) However, a luminescent material such as a conventional artificial tile or artificial stone which is made noctilucent, for instance, by the above light accumulationpigmenthas several o o hours at most; for sustaining a declining brightness over 3mcd/m 2 which is a lower limit at which a person can ensure a contour of things, from a saturated state after irradiation at 200Lx with a D65 commonly used light source; and the above proposed material (Japanese Patent Laid-Open No. 60-137862) has only one hour.

In addition, there was a problem that brightness required for a clear visibility which is thought to be necessary for a refuge instruction in a power cut for about 15 minutes was not in an enough level. These problems were common as a problem that enough luminescence performance is not obtained either in case of a light emission by ultraviolet rays.

Furthermore, there was a problem that only a surface layer of 1 mm deep at most from the surface can emit light and a light accumulation material or the like included in a deeper side of a compact of an artificial stone can not act at all, in either a case of an artificial stone (an artificial tile) being made noctilucent by blending a light accumulation pigment or a case of an artificial stone being made luminescent by ultraviolet rays.

For this reason, a thick light emission layer could not i be provided. Thus there was a fundamental problem on luminescence performance described above that an extension of an noctilucent time was difficult, for instance, on an noctilucent artificial stone mixed with a light accumulation material.

Actually, owing to these problems, a practical use taking ooo advantage of light accumulation noctilucence which function attracts attention as refuge induction guides in a power cut •gee oo ~in an underground shopping center, for instance, is limited to 20 a paint, tape, or a film which includes the light accumulation material.

It is not practical from the view point of a cost to blend a luminescent substance in an artificial stone as parts which do not contribute to a light emission actually, because the noctilucent substance such as a light accumulation material and the luminescent substance with ultraviolet rays are expensive and raise a whole cost of an artificial stone product to 3 to times higher even with a small quantity of addition.

In addition, a conventional artificial stone could not be employed for floor materials, for instance, to which an abrasion resistance is required, as it has a problem not only in the luminescence performance but also in a physical property such as a strength, an abrasion resistance, and weatherability.

Thus, the performance and the use of the conventional artificial stone which is noctiluscent or luminescent with ultraviolet rays were extremely limited.

Considering these situations, the present inventors have i proposed an artificial stone; which realizes a high strength and high hardness as an artificial stone including an inorganic aggregate and filler with a resin and a deep hue like a natural •e stone; allows a light emission with thickness by blending a light accumulation material or an ultraviolet ray luminescent material; enables a contour thickness as an artificial stone S*4 to be bigger; and besides enables a luminescent time to be longer (for instance, W098/39268, W098/35919) o*o These proposals are essentially characterized by; using several groups of inorganic materials which average particle diameters are different, ina specific blending ratio; employing transparent inorganic materials for groups with bigger particle diameters; blending light accumulation materials or ultraviolet ray luminescent materials for groups with smaller particle diameters, or coating them beforehand on the surface of the transparent inorganic particles with bigger particle diameters by baking or the like.

And these proposals were based on new findings that it is possible to increase a thickness contributing to a luminosity of a light accumulation material or the like by means of controlling an inner structure of the artificial stone.

Actually, an artificial stone based on the proposal of the present inventors enables brightness of 3 mcd/m 2 or more to continue for about 8 hours.

However, after that, the present inventors have investigated as a big subject to control a relationship between a structure of the artificial stone and the luminescence performance; for the purpose of improving the luminescence .:e.oi S performance of light accumulation materials and luminescent S materials with ultraviolet rays, for raising the initial brightness of light accumulation luminescence and besides enabling the luminos i ty at apredeterminedbrightness to continue for a longer time.

It is to realize a light accumulation luminescent artificial stone which shows in maximum non energetic luminescence performance of a predetermined brightness at night or in a power S 20 cut and a light emissive artificial stone with ultraviolet rays radiation which shows an energy-saving property in maximum.

Besides, concerning on the control, the present inventors have investigated as a subject to sustain and improve a physical property of extremely high quality and high function such as strength, surface hardness, abrasion resistance, weatherability, a color tone, and waterproofing/chemical resistance, for instance, which the present inventors have 6 realised till now.

Disclosure of Invention According to a first aspect of the present invention, there is provided an artificial stone, comprising: a transparent aggregate selected from the group consisting of quartz, silica rock, rock crystal, glass, and silica; at least one kind of a light accumulation material and a luminescent material by ultraviolet rays selected from the group consisting of a strontium aluminate base substance and a zinc sulphide base substance; and a resin; wherein: the transparent aggregate has a particle diameter of 0.1 mm or more and 2/3 or less of a thick of the artificial stone once cast and hardened, and is present in a volume ratio of 49 or more and 70 or less, 20 the resin is present in a volume ratio of 30 or more and 51 or less, the light accumulation material and/or the luminescent material by ultraviolet rays has an average particle diameter of 10 pm or more and 300 pm or less, and 25 is present in a volume ratio of 15.61 or less, and no substantial amount of non-transparent aggregate of larger than 0.1 mm in particle diameter is ei*- *included; and wherein the luminescence performance of the 30 artificial stone is higher than that of the included light oooo accumulation material and/or luminescent material by ultraviolet rays per se.

Preferably, said artificial stone has high luminescence performance in a lower filling factor (vol%) of the artificial stone than the maximum filling factor (vol%) of the included light accumulation material and/or luminescent material by ultraviolet rays per se.

H \Isabe1H\Seci\43583.doc 9/06/06 7 Preferably, the particle diameter of the transparent aggregate is 0.3 mm or more.

Preferably, the average particle diameter of the transparent aggregates is 1/20 or more and 1/3 or less of a thickness of the artificial stone after it is cast and hardened.

Preferably, the transparent aggregate particles have an irregular surface configuration.

Preferably, the average particle diameter of the light accumulation and/or luminescent material is 40 pm or more and 150 pm or less.

The artificial stone may include an inorganic filler with a particle diameter less than 0.1 mm.

The average particle diameter of the filler may be 30 pmn or more and 70 pm or less.

A volume ratio of a filler to a light accumulation material, a luminescent material by ultraviolet rays, or the mixture of the both may be 0 or more and 100 or less as filler/(light accumulation 20 material and/or luminescent material by ultraviolet rays).

In some embodiments the transparent aggregate is quartz or rock crystal and the filler is aluminium hydroxide or silica.

In some embodiments the transparent aggregate is 25 a glass and the filler is silica or aluminium hydroxide.

In some embodiments the time from a saturated state after an exposure at 200 Lx with the D65 commonly used light source to brightness of 3 mcd/m 2 is 12 hours or longer.

30 The artificial stone may be lamination oe constituted as a surface material.

The artificial stone may be constituted as a part •of a surface.

Provision of at least preferred embodiments is based on the following which has resulted from the work of the inventors. Namely, noctilucence/luminescence performance can be improved greatly by careful structure H: \Iabe1H\SpeCi\43583.doc 9/06/06 8 of the artificial stone and control of the following factors Particle diameter of transparent aggregate; Configuration of transparent aggregate; Particle diameter of light accumulation material/ultraviolet rays luminescent material; Volume rate of transparent aggregate, and volume ratio against filler; Sort of transparent aggregate, and combination of it and sort of filler.

Brief Description of Drawings Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 illustrates an aspect of cutting out the artificial stone and the surface processing; Fig. 2 illustrates a lamination composition of the noctilucent/luminescent artificial stone; i 20 Fig. 3 shows the recessed noctilucent/luminescent artificial stone; and ~Fig. 4 shows the integrated noctilucent/luminescent artificial stone by implantation.

o Best Mode for Carrying Out the Invention Preferred embodiments of the present invention will be described hereinafter.

In other words, the noctilucent/luminescent artificial stone of preferred embodiments is an artificial 30 stone including a transparent aggregate, at least one kind "selected from a light accumulation material and a luminescent material by ultraviolet rays, and a filler "i mixed if needed along with a resin; being characterised by having higher luminescence performance of the artificial stone than that of the included light accumulation material and/or luminescent material by ultraviolet rays per se.

H: \IabelH\SpeCi\43583.doc 9/06/06 9 The luminescence performance with such a feature has never been thought of till now. Such an artificial stone is realised as a blended complex with not only a light accumulation material and/or a luminescent material by ultraviolet rays but also a transparent aggregate, a resin, etc, and has superior luminescence performance to that of a luminescent material and/or a luminescent material by ultraviolet rays per se.

The luminescence performance of a light accumulation material and/or a luminescent material by ultraviolet rays per se, is evaluated in the following ways, for instance.

As for sole luminescence performance of these light accumulation materials and/or luminescent materials by ultraviolet rays per se, since these are used in a form of particles, first of all, these particles are charged in a transparent vessel with an upper part opened and with a same depth as a thickness of the artificial stone in casting, and are pressurised with a vibration to be a close packed state. The condition shows the condition where particles consisting of light accumulation materials and/or luminescent materials by ultraviolet rays are packed in maximum keeping the initial size and shape without being damaged, and the condition where any longer 25 it cannot be filled up any more. This condition is composed by these particles and air existing among these.

Then, the luminescence performance can be .O*o measured in such a close packed state.

For instance, after making each strontium aluminate based light accumulation materials (made in NEMOTO Co., Ltd.) with different particle diameters into the closed packing state in ooo H:\Iaabe1H\Speci\43583.doc 9/06/06 10 (THIS PAGE IS INTENTIONALLY LEFT BLANK) 0 0

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Table 1 Light accumulation Average particle diameter (pim) material 10 20 40 80 150 300 Maximum filling factor 30.56 36.11 38.89 41.67 44.44 47.26 (volume Specific gravity 1.1 1.3 1.4 1.5 1.6 1.7 True specific gravity 3.6 3.6 3.6 3.6 3.6 3.6 Brightness after 15 minutes 102.3 148.5 189.3 301.8 405.6 395.2 (mcd/m 2 Decay time to 3 mcd/m 2 5h30m 7h15m 10h45m 10h15m 18h 17h 000 Sees se S 5 5 5 5 S S S S 5 55 0 50 S SO 55 55 5* 5555

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5 555 On the other hand, an artificial stone including a light accumulation material with an average particle diameter of 150 pm shown in Table 1 as a composition, was cast and hardened to be an artificial stone of 5 mm thick, and its luminescence performance was measured. The results are shown in correspondence with a filling factor (volume of a light accumulation material in Table 2.

Table 2 Light accumulation Brightness after material filling factor 15 minutes Decay time to 3mcd/m 2 .(volume (mcd/m 2 0.29 61.29 1.44 105.3 6h 3.19 178.6 10h45m S4.37 217.6 11.19 372.3 19h45m 15.61 426.1 24h By the way, brightness and its decay in Table 1 and Table 2 are measured with "BW33 luminance meter" made by TOPCON CORPORATION. Itissimilarinthefollowingdescriptionaswell.

As is clear, for instance, in a comparison between Table 1 and Table 2 for a case of a light accumulation material of average particle diameter 150 pm, it is understood that the decay time to 3 mcd/m 2 of an example of an artificial stone with a filling factor of 11.19 volume in the present invention was 19 hours and 45 minutes which exceeded a level of 18 hours of a lightaccumulationmaterialperse; andthat initialbrightness after 15 minutes of an artificial stone with a filling factor of 15.61volume wasalsohigher thanthatof a lightaccumulation material per se.

These kind of results are confirmed not only in case of a light accumulation material with an average particle diameter of 150 pm, but also in any case with 10 to 300 pm shown in Table i.

It is thought tobecommonthat the luminescence performance of a sole luminescent material will drop by means of being blended with other components. However, it is surprising that the luminescence performance of the artificial stone of the present invention is superior to that of a sole light accumulation material, in other words, that the luminescence performance is, on the contrary, improved with blending, being different from such a common knowledge.

The following reasons can be guessed.

In the artificial stone, almost all light accumulation 20 materials can effectively absorb an energy of light (ultraviolet rays) given with radiation such as a sun light and a fluorescence light, as a result of scattering or irregular reflection of the light in inside of the artificial stone due to a blend or a conjugation with transparent aggregates and others.

Therefore, the absorbed light in inside of the artificial stone is accumulated effectively and the luminescence can be made effective.

The above-mentioned phenomenon is recognized not only in a light accumulation material but also in luminescent materials by ultraviolet rays of the present invention.

Thus, in the present invention, a composition is provided for a preferred artificial stone to allow the above-mentioned phenomenon.

This artificial stone, at first, comprises an inorganic aggregate, a light accumulation material (in other words, a light accumulation luminescent material) or a luminescent material emitting light by means of ultraviolet irradiation, anda resin, wherein a part or a whole of said inorganic aggregate consists of a transparent aggregate. When a transparent aggregate is one part of the inorganic aggregate, the ratio is determined i with a consideration to a physical function which is needed by an application of a noctilucent/luminescent artificial stone of the present invention or its formation, and to a luminescent function.

Therefore, in the present invention, the transparent aggregate is included as an indispensable matter.

20 And the artificial stone includes, as needed, an inorganic or organic filler, and a minor constituent of a silane coupling agent, a hardening agent, or the like.

A transparent aggregate in these compositions includes inorganic substances with a high transparency such as quartz (silica rock), rock crystal, glass, and silica, for instance.

For these transparent aggregates, an inorganic aggregate such as natural rocks of non-transparency, minerals, and ceramics can be concomitantly employed in a permitted range.

A fillerblendedwith anaggregate asneeded issmallgranule powder with a much finer particle diameter than aggregate, and includes, for instance, inorganic substances such as aluminium hydroxide, glass powder, silica powder, quartz (silica rock) powder, and calcium carbonate, and organic substances such as plastic powder or a plastic bead.

For a light accumulation material or a luminescent material by ultraviolet rays, various kinds of materials including a conventionally known material or a commercial material can be employed appropriately. There is, for instance, a strontium o aluminate base substance, a zinc sulfide base substance, or the like.

As a result of further investigation on details of the noctilucent/luminescent artificial stone which inventors have already proposed, the present inventors have found that the o o luminescence performance can be unexpectedly and remarkably .:"improvedwith a minute control of the structure, andhaveproposed othe followings. One of the important factors is, in the first 20 place, a particle diameter of a transparent aggregate.

By the way, the luminescence performance is evaluated with a light accumulation luminescence in the following. In the evaluation method, according to JIS "light accumulation safety sign board" Z9100-1987, after irradiating at 200Lx by the common light source until brightness is saturated, a decay time until brightness becomes 3 mcd/m 2 is considered as the standard in the case of evaluating a performance. Incidentally, 18 brightness of 3 mcd/m 2 is considered to be a lower limit at which a person can visibly identify a contour of a thing.

In addition, brightness at an elapsed time after irradiation such as initial brightness after 15 minutes may also be useful in evaluating artificial stone.

In the present invention, the particle diameter of the transparent aggregate is determined to be 0.1 mm or more and 1/1.5 or less of a thickness of the artificial stone after the artificial stone was cast and hardened. In the above, "cast and hardened" means a state that a material mixture or a composition of the artificial stone in a flow condition is formed and hardened with compression or the like after being cast in a mold or is formed and hardened to a predetermined shape from the flow condition by means of a continuous belt formation or the like. The particle diameter of a transparent aggregate is determined to be 1/1.5 or less of a thickness of the artificial stone in such a "cast and hardened" state.

In embodiments of the present invention, a i 20 preferable particle diameter of the aggregate is determined to be 0.3 mm or more.

a e In case of a particle diameter of a transparent aggregate with less than 0.1 mm, the decay time or brightness of 3 mcd/m 2 is merely several hours, namely, 1 S 25 to 3 hours which is the same performance as the conventional one. In order to make the time at least six hours, the maximum particle diameter of the transparent aggregate must be 0.1 mm or more of a thickness of the artificial stone. In order to make the time for reaching 0 30 from the saturated state to the brightness of 3 mcd/m 2 8 hours o• 0ooo oooo• H: \Iabe1H\SpCi\43583.doc 9/06/06 or longer and further 12 hours or longer, the preferable particle diameter may be 0.3 mm or more.

On the other hand, the particle diameter should be 1/1.5 or less of the thickness of the artificial stone. Because, in a case exceeding 1/1.5, a practical noctilucent/luminescent artificial stone isnotactuallyprovided, as aphysicalproperty such as strength required to the artificial stone is difficult to be obtained after the artificial stone was cast and hardened.

The luminescence performance of the artificial stone (a board thickness of 5 mm) including merely 2 vol% (3.89 wt%) of an strontium aluminate base light accumulation material (NEMOTO Co., Ltd., G-300C) for a light accumulation material, for instance, is indicated in Table 3. In Table 3, .the results are shown with the decay time af ter a saturated state being irradiated 15 at 200Lx with the D65 commonly used light source for 60 minutes.

SA composition (volume of the artificial stone is as S' follows.

Quartz (pulverized product) 19.98 Aluminium hydroxide 32.11 (average particle diameter 40 pm) Light accumulation material 2.00 (average particle diameter 40 pm) MMA resin 44.74 Others remainder (Silane coupling agent, a hardening agent, etc.) Table 3 Luminescent time Quartz diameter range (mm) after irradiation Less than 1.2 1.2 0.6 0.6 0.3 0.3-0.1 by light (hr) 0.1 1 35.47 29.48 30.39 24.56 14.23 2 16.82 13.20 13.16 11.13 3.871 4 7.253 5.957 5.671 4.971 6 4.372 3.972 3.872 3.082 8 3.326 3.121 3.012 3.087 In the table 3, about samples including merely 2 vol% of 5 a light accumulation material, change of the brightness (mcd/m 2 by the time after radiation is shown for every quartz particle diameter range.

Table 3 shows that it is necessary to set the aggregate particle diameter to 0.1mm or more, and that it is desirable to set aggregate particle diameter to 0.3mm or more in order to make time to 3 mcd/m 2 into 6 hours or longer.

In addition, when the particle diameter of the transparent aggregate exceeded 1/1.5 of the board thickness, that is 3.4 mm, though the result is not shown in Table 1, the cast and hardened artificial stone had a weak bend strength and was not a practical product.

In addition, when the aggregate particle diameter is less than 0.1 mm, the luminescence performance was improved with an increase of blending rate of a light accumulation material.

1 ooooo .l e However, as a light accumulation material is an extremely expensive, it is not practical to increase the used quantity at all. For this reason, it is extremely important for the noctilucent/luminescent artificial stone to achieve the best luminescence performance with a minimum use rate of a light accumulation material.

In such a point of view, a prescription of the particle diameter of the transparent aggregate related to the present invention shows a conspicuity of the invention.

0 In the present invention, the average particle diameter of the transparent aggregate is further preferably 1/20 or more andl/3orlessofthethicknessofthecastand hardened artificial stone. By making average particle diameter into this range, it becomes possible to lengthen certainly the decay time until brightness declines to 3 mcd/m 2 in 12 hours or longer.

Table 4 shows changes of the decay time to brightness of 3 mcd/m 2 with variation of average particle diameters of quartz on the artificial stone (board thickness of 5 mm) of the following composition (volume 0 uartz (pulverized product) 49 Aluminium hydroxide 14 (average particle diameter 40 pm) Light accumulation material G-300C (average particle diameter 40 pm) MMA resin 31 In the above composition, minor constituents such as a silane coupling agent or a hardening agent are omitted. It is *5*

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similar in the following description as well.

Table 4 Maximum particle Average particle Time to 3 mcd/m 2 diameter (mm) diameter (mm) 2.38 0.25 12h15m 2.38 1.0 13h30m 2.38 1.2 13h45m 2.38 1.6 13h 2.38 1.8 9h45m Time to 3 mcd/ m 2 after irradiation at D 65 200Lx X 60 minutes (more than saturation time) is shown.

"From Table 4, a significance of the average particle diameter with 1/20 or more and 1/3 or less of a board thickness 10 of a cast and hardened artificial stone is understood.

On the other hand, it is preferable to employ a transparent aggregate, having not a regular crystal cleavage plane and not a spherical shape but an irregular surface configuration. This is characterized at first in a comparison between quartz (silica 15 rock) and rock crystal. These are usually pulverized to become a predetermined particle diameter of product. A pulverized product of rock crystal tends to have a regular surface as it is highly crystallized. On the other hand, a quartz product does not have such a tendency. The quartz product consists of grains with an irregular and rough-hewn surface configuration as a whole. In addition, in case of a glass bulb, there is not such an irregular surface on it as is seen on a pulverized product of quartz or normal glass.

Such a difference affects the luminescence performance of the noctilucent/luminescent artificial stone.

Table 5 shows such a contrast.

In any case, composition (volume was as follows.

Transparent aggregate Aluminium hydroxide 14 Light accumulation material G-300C MMA resin The maximum particle diameter of the transparent aggregate was 2.38 mm, and the board thickness of cast and hardened artificial stone was 5 mm. The decay time to 3mcd/m 2 after 15 irradiation at 200Lx with the D65 commonly used light source :to a saturated state is shown in Table Table Transparent aggregate Decay time to 3 mcd/m 2 Glass pulverization product Glass ball 9h Quartz pulverization product 13h Rock crystal pulverization product 8h30m A clear contrast is recognized in Table 5. It is guessed that such a contrast reflects a degree of irregular refraction 24 frequency in grains of the light which entered the transparent aggregate. It is conceivable that rock crystal with a highly crystallised plane or a glass ball with a spherical surface has less degree of such an irregularity than the pulverised product of quartz or glass.

According to the examination by the present inventors, it confirms that it is excellent from a viewpoint of the luminous performance to have the particle diameter of the light accumulation material large, and that the time necessary for irradiation by light for reaching the initial saturated state increases when the particle diameter is large.

For instance, about the artificial stone including 5 vol% of a light accumulation material, 49 vol% of an aggregate and 31 vol% of MMA resin, as is shown in Table 6, it is understood that it is desirable to use a strontium aluminate base light accumulation material with an average particle diameter of 20 pm or more, further preferably 40 pm or more, in order to extend the decay time to brightness of 3 mcd/m 2 after irradiation at 200 Lx with D65 to a saturated state in more than 12 hours.

o*oo ooooo H:\Isabe1H\Speci\43583.doc 9/06/06 Table 6 Average particle diameter of light accumulation material (pm) Brightness/time 20 40 80 150 Brightness after 3.213 3.809 4.346 4.529 4.975 ten hours (mcd/m2) Brightness after Brightnes after 3.007 3.415 3.523 4.079 12 hours (mcd/m Decay time to 10h5m 12h 13h5m 13h30m 15h5m 3 mcd/m 2 In the present conditions, it is desirable to employ the average particle diameter of less than about 300 pm and further 5 preferably less than 150 pm from a view point of availability.

*In addition, in the artificial stone of the present invention, an inorganic filler with a smaller particle diameter than the inorganic aggregate such as said transparent aggregate, in other words, with a particle diameter less than 0.1 mm, can be used. Ablendof these inorganic fillers is not always needed for a composition of the noctilucent/luminescent artificial stone of the present invention. However, the filler is expected to enable a used amount of a resin in a composition of the artificial stone tobe reduced, to contribute to a dense structure of theartificial stone, and further tocontribute toan effective luminescence with a little amount of used light accumulation materials.

The preferable average particle diameter of these filler 26 is 30 pm or more and 70 pm or less.

The filler with a particle diameter of 0.1 mm or more makes it difficult to provide a dense structure in the artificial stone, and consequently makes a factor for decreasing the luminescence performance.

In embodiments of the noctilucent/luminescent artificial stone of the present invention, blending ratio of the aggregate, filler, and a light accumulation material and/or a luminescent material should be paid attention along with a definition on the particle diameter as the above. In the blending ratio, especially, a volume rate occupying in a three-dimensional structure of the artificial stone is important. According to our findings, the volume rate is clearly appreciable factor from the viewpoint of the luminescence performance along with a physical property of the artificial stone as a threedimensional structure.

In the noctilucent/luminescent artificial stone of various embodiments, a preferable volume rate of the transparent aggregate is determined to be 20 or more and or less. When the filler is employed, though it is not specifically limited, it is a desirable mode to control filler/light accumulation material and/or luminescent material by ultraviolet rays (by the volume ratio) into 100 or less.

Table 7 shows a decay time to brightness of 3 mcd/m 2 after irradiation at 200 Lx with the D65 commonly used light source to a saturated state, for samples consisting of; strontium aluminate base light accumulation material (G-300C) with an average particle diameter of pm as the light accumulation *o*oo *o *ooo H:\I\abe1H\Speci\43583.doc 9/06/06 material, aluminium hydroxide with an average particle diameter of 40 pm as the filler, quartz (a pulverized product) with a maximum particle diameter of 2.38 mm and an average particle diameter of 1.2 mm as the transparent aggregate, and MMA resin.

Table 7 Aggregate (quartz) volume rate 10 20 60 80 Time to 3mcd/ 6.5 12.5 13.5 12 (hr) From Table 7, it is understood that the above prescribed 10 range enables the decay time to 3 mcd/m tobe 12 hours or longer.

Furthermore, in the noctilucent/luminescent artificial stone of the present invention, the luminescence performance can be improved by means of a combination with the transparency oo.

aggregate and the filler. Table 8 shows the above combinations.

The employed materials are; the transparent aggregate with a maximum particle diameter of 2.38 mm and an average particle diameter of 0.8 mm, the filler with an average particle diameter of 40 pm, and the light accumulation material (strontium aluminate base: G 300C) with an average particle diameter of

S

40 pm. The volume ratios are; 50 of a transparent aggregate, of a MMA resin, 15 of the filler, and 5 of the light accumulation material.

Table 8 Brightness after one Decay time to Transparent aggregate Filler hour of irradiation by 3 md/m2 light (mcd/m 2 cd Aluminium hydroxide 25.83 13h30m Quartz Silica 24.98 12h (pulverized product) Glass powder 23.71 Silica 57.49 12h15m Aluminium hydroxide 52.04 12h Glass* Glass powder 25.26 (pulverized product) Calcium carbonate 38.14 8h Quartz powder 18.68 4h45m *Commonly commercial soda glass is used for glass.

r 5 Table 8 also shows results after irradiation at 200Lx with the D65 commonly used light source to a saturated state. It is understood that aluminium hydroxide or silica as the filler is preferable for quartz as the transparency aggregate, and that silica or aluminium hydroxide is preferable for glass.

In addition, it is understood that selection of such combinations enables the decay time to 3 mcd/m 2 to become 12 hours or longer.

It is grasped in Table 9 from a contrast of a light transmittance that the effective luminescence performance with these combinations is seen in case of luminescent materials by ultraviolet rays.

29 Table 9 Transparent Filler All beam Diffusivity Black light aggregate permeability Permeability Glass Silica 48.6 45.5 14.3 (pulverised Aluminium 44.1 41.2 12.9 product) hydroxide Glass powder 35.4 33.2 11.7 Calcium carbonate 21.8 20.4 2.3 Quartz powder 22.5 21.0 5.2 Table 9 shows the results on samples of the glass for the transparent aggregate in Table 7. It is well understood that the above combination is preferable.

As is described in the above, an embodiment of the present invention provides a noctilucent/luminescent artificial stone including the transparent aggregate, the filler, and the light accumulation material along with a resin in which the time to 3 mcd/m 2 after irradiation at 200 Lx with the D65 commonly used light source to a saturated state is 12 hours at least.

Embodiments of artificial stone in accordance with the present invention having the superior luminescence performance as described in the above may have various compositions as above and various manufacturing methods as well.

About composition, an appropriate blending with 20 function components such as the filler and trace components along with the above transparent inorganic aggregate and a resin may be considered for the artificial stone from the viewpoint of strength, weatherability, abrasion resistance, surface non-slipperiness, a colour 25 tone, incombustibility, and other many functions.

Of course, the transparent aggregate may occupy a whole amount of aggregate components as was described already, or certain inorganic aggregates of nontransparency may be used jointly as one part of 30 aggregates, in the noctilucent/luminescent artificial stone. However, even in the case of the combined use, the H:\Isabe1H\Speci\43S83.doc 9/06/06 30 amount of the transparent aggregate is preferably 30 vol% or more and 80 vol% or less of the cast and hardened artificial stone in order to realise the superior performance like 12 hours or longer of the decay time to brightness of 3 mcd/m 2 after irradiation at 200 Lx with the commonly used light source to a saturated state.

It is needless to say that the inorganic aggregate including the non-transparent aggregate should have a maximum particle diameter of 1/1.5 or less of the board thickness after cast and hardened and may be blended as a mixture with various particle diameters having a particle diameter distribution.

In practice, it is preferable that the inorganic aggregate consisting of the transparent aggregate or the transparent aggregate and non-transparent aggregate has a particle diameter distribution of a close-packing or the vicinity as is well known in a concrete engineering, and besides that the average particle diameter is 1/20 or more and 1/3 or less of the thickness of the cast and hardened artificial stone as is described above.

In addition, it should be a naturally considered point what kind of colour tone and design in bright field would be the obtained noctilucent/luminescent artificial stone. An appearance of granite and marble is often aimed at because the product is hard to be obtained as they are natural and their colour and luster are beautiful. In this ee case, the colour and luster is an important subject to ""determine a value of granite and marble. There are various sorts of colours in the natural granite and marble, such as complete black to white or red, and different degrees in the same colour.

ooe° When giving a colour to each kind of an artificial stone, a colour reproducibility is a problem to obtain a product with a medium colour tone, though, in 35 case of a black product, for instance, just black particulate matters of natural rocks have only to be used.

In addition, it is not so easy to obtain the unique luster H:\Isabe1H\Speci\43583.doc 9/06/06 31 of the marble, even if the colour is obtained.

In at least some earlier artificial stone compositions it has been difficult to give a luster or a depth, even in the case of giving a colour by a blended resin with dye or pigment.

As opposed to this, in the artificial stone of the present invention, transparent inorganic aggregates can be principally employed. For instance, the transparent inorganic aggregate obtained by crushing quartz base natural rock, glass, or fused silica can be employed.

By means of employing these transparent aggregates, the colour of the artificial stone in a bright field can be controlled and allowed to have a depth and a luster owing to the existence of a quartz base granule component with transparency.

In addition, in some embodiments of noctilucent/luminescent artificial stone in accordance with the present invention, the much finer filler than the aggregate is employed along with it, for instance, preferably, with a particle diameter of 0.1 mm or less and an average particle diameter of 30 pm or more and 70 pm or less. The filler includes natural or various kinds of artificial materials preferably such as aluminium S" hydroxide, silica, and glass powder, for instance. These 25 inorganic fillers have much finer particle diameter than S. -the above aggregates, and contribute to properties such as e 9hardness, softness, and surface non-slipperiness of the obtained artificial stone, while they invade into spaces among the inorganic aggregates and locate to fill the spaces among grains.

As a part of blend for these fillers, components such as manganese dioxide, titanium dioxide, zirconium silicate, and iron oxide may be added for adjusting a colour tone; and antimony trioxide, boron compound, 35 bromine compound and the like for giving a flame retardance.

In addition, an inorganic antimicrobial agent may H:\IsabelH\Speci\43583.doc 9/06/06 32 be combined. The artificial stone of antibacterial activity is useful for a bathroom, floor of rest rooms, wall, and handrail, for instance. It is also useful in medical facility, a food processing facility, and the like.

As an inorganic antimicrobial agent, there are silver, zinc, and copper base inorganic materials, for instance.

Resins can be selected from the wide range as described above.

The resin includes, for instance, an acrylic resin, a methacrylic resin, an unsaturated polyester resin, an epoxide resin, a silicone resin, a silicone rubber, and the like. In these, a methacrylic resin, an epoxide resin, the mixture, or the copolymerisation resin is shown to be preferable.

An organic pigment such as an azo base, a phthalocyanine base, dye, etc. may be blended to these resins in order to adjust the colour tone.

In addition, a light stabiliser or a fire retardant may be included.

Resin components contribute to wrapping the aggregate and the filler which are component for forming a skeleton of the artificial stone and bonding the whole, and have a function for giving an elasticity or a tensile strength to the completed artificial stone.

About resin component, the volume rate may be .about 70 or less, but more preferably in practice vol% or more and 35 vol% or less when characteristics such as strength, durability, natural rock-like appearance, and tint, or non-slipperiness and the like for the artificial ge stone are considered.

The artificial stone product with an excessive eo. resin component appears plastic-like, and the artificial 35 stone becomes merely nominal. When the resin component is i excessively little, the product becomes fragile and not suitable for use though the appearance of the product H: \sabe1H\SpeCi\43583.doc 9/06/06 33 approaches to a natural tone.

About resin components in the present invention, various kinds of resin can realise the artificial stone having the superior and essential performance for the noctilucent/luminescent artificial stone. However, a methacrylic resin, particularly MMA (methyl methacrylate) resin is preferably employed as a main component, in the artificial stone for the use to which weatherability, chemical resistance, hardness, abrasion resistance, transparency, depth of colour tone and the like are demanded.

Instead of the main composition of the artificial stone consisting of the inorganic aggregate, the inorganic filler, and the resin as described above, the flexible composite with high hardness which have been already proposed by the present inventors can be composed for the artificial stone similar to the noctilucent/luminescent artificial stone.

That is an artificial stone with a surface hardness of 400 or more with Vickers hardness (JISZ2244) and a radius of curvature of R25mm at which bending is possible without damaging for a board of 3 to 15 mm thick.

In the composite, the inorganic components including the inorganic aggregate can occupy 50 vol% or more of the total and organic components such as resin can be less than 50 vol%. A main component of the organic component is a methacrylate resin. More concretely, it is shown as a denatured MMA resin with blending polymethyl methacrylate (PMMA) and one or more materials selected from methyl methacrylate (MMA) monomer, 2-ethylhexyl methacrylate monomer, 2-ethylhexyl acrylate monomer, 2- *o ethyl oo* *oeo H:\IsabeII\Speci\43583.doc 9/06/06 34 (THIS PAGE IS INTENTIONALLY LEFT BLANK)

U

*0 0 0 0 0 0U 00 0 0 00@0 00~0 *00* 00 0 0 *0e0 0 **00 0000 *00000 0 H:\IBabC1H\Speci\43583.doc 9/06/06 pentyl methacrylate monomer, butylmethacrylate monomer, and cyclohexyl methacrylate monomer.

Table 10 shows the light accumulation luminescence performance namely the noctilucent property of the artificial stone obtained with each kind of resin.

The employed materials are; the aggregate of pulverized quartz with a maximum particle diameter of 2.38 mm and an average particle diameter of 1.2 mm, a filler of aluminium hydroxide with averageparticlediameter of40pm, andastrontiumaluminate base light accumulation material with an average particle diameterof 40 pm. The compositionsare 50vol% of the aggregate, 13 vol% of the filler, 5 vol% of the light accumulationmaterial, and 30 vol% of the resin. The thickness of the cast and hardened artificial stone is 5 mm.

*i* Table Brightness after one hour Decay time to Resin of irradiation by light 3mcd/m 2 (mcd/m 2 3m MMA resin 58.72 12h Unsaturated polyester (DAINIPPON INK AND CHEMICALS, 57.85 1 INCORPORATED "FG208") Degeneration MMA resin 57.98 11h45m (Mitsubishi Rayon Co., Ltd. "XD7005") *Light irradiation irradiation at 200Lx with D65 for minutes (more than saturation time) In addition, in the noctilucent/luminescent artificial stone of the present invention, the above transparent aggregate :may be baked or coated at a room temperature with a noctilucenct light accumulation material or a luminescent material by ultraviolet rays.

In case of a coating with baking, fine particles with a diameter of several pm to several dozens pm, for instance, to 50 pm, more preferably 20 to 40 pmmaybe coated on the surface of the transparent aggregate particles. More concretely, the 15 coating can be carried out with a baking at a high temperature of around 120 to 1200 oC.

The luminescent coating substance may include various kind of light accumulating substances or light emitting substances by ultraviolet irradiation such as strontium aluminate and zinc sulfide.

As for a baking method, various conventional methods may be employed. For instance, the transparent inorganic aggregates are mixed in a dispersed solution of particles of light accumulation materials such as strontium aluminate or the paste, are dried and baked.

A coating at a room temperature can be done in the above dispersion solution or a paste with a transparent sticky substance (binder).

The noctilucent/luminescent artificial stone of the present invention can be made with casting and hardening a liquid or floating mixed raw material or composition.

Casting and hardening can be done with a casting formation, a compression molding, and a stepless belt formation.

A compression molding, for instance, is done in the following way; casting, beforehand, a necessary quantity of the 15 compositionforthecompletedproductsuchas inorganic aggregate, filler, and resin components into a drag as a horizontal molding-flask; matching a cope; and compression molding, for instance, with a bearing stress of 5 to 100 kgf/cm 2 At a compression of this molding, the composition can be heated to o 20 a temperature of roughly 80 to 180 °C for 5 minutes to several .hours.

In addition, in the compression molding with heating, oscillation can be given to the molding-flask along with compression to improve a flowability of the above material in the molding-flask.

Of course, a shape for the real product with the artificial stone in the present invention does not need to be limited to 38 a flat board. It may be an induction projection for an eyesight handicapped person, have a surface with projections, or be composed as a stepped shape. Many other shapes may be considered.

In embodiments of the present invention, a roughsurfaced processing may be done on the surface of a cast and hardened compact.

As a method for this purpose, first of all, a selective removal method of a resin component is adopted.

In other words, skin surface processing with squirting highly pressurised water onto a surface of a compact after removing from a molding-flask, for instance, is effective.

That is water-jet machining.

In this water-jet machining, many conditions are selected; such as a surface hardness and a surface strength of the processed material, and a hydraulic pressure, a diameter of an ejection nozzle, and a distance between a material surface and a nozzle outlet for forming a predetermined depth of grooves on the surface in uniformity coping with these properties. It is not defining, but, for instance, a hydraulic pressure of about 100 to 1500 kgf/cm 2 can be usually employed for a nozzle of around 5 to 50 mm high.

ooooo S"There is no limit in particular about a nozzle 25 for squirting highly pressurised water and the system. All S. kinds of nozzles are employed.

By means of water-jet machining, surface roughening is realised and the artificial stone, for instance, with non-slipperiness and a deep touch of a material is produced. Besides, what should be emphasised in preferred embodiments of the present invention, is the low likelihood of clouding of a colour of the artificial stone by means of water-jet machining.

oo ~The noctilucent/luminescent artificial stone of the present invention may be required to provide nonslipperiness for certain applications, for instance, for a passage or a step in which refuge indication is needed H: \Iabe1H\Speci\43583.doc 9/06/06 39 against a dark background such as a road or a platform, or for a step in a station to provide assistance in the event of a power cut. Water-jet machining can give such nonslipperiness to the artificial stone.

As for giving the non-slipperiness, the present inventors have proposed in another invention an artificial stone; fundamentally including an inorganic aggregate and a resin and having a convexoconcave surface in which inorganic aggregates are exposed, wherein an average depth of the surface grooves are 0.02 mm or more and 1.0 mm or less, particularly of 0.05 mm or more and 0.8 mm or less.

By utilising the above invention, the following can be provided; a non-slippery artificial stone including an inorganic aggregate and a resin and having a convexoconcave surface in which inorganic aggregates are exposed, being characterised by that a skid resistance value BPN (ASTM E303) is 60 or more at a wetting face and or more at an oil face, and a non slippery artificial stone characterised by that a skid resistance value BPN is or more at a wetting face and 35 or more at an oil face; a non slippery artificial stone including an inorganic aggregate and a resin and having a convexoconcave surface in which inorganic aggregates are 25 exposed, being characterised by that a skid 0 0 ooo g H:\IBabe1H\SpeCi\435a3.doc 9/06/06 resistance valueC.S.R. (JISA5705 andJISA1454 are referenced) is 0.8 or more at a wetting face for men's shoes anda non slippery artificial stone characterized by that a skid resistance value C.S.R. is 0.45 or more at an oil face; a non slippery artificial stone including an inorganic aggregate and a resin and having a convexoconcave surface in which inorganic aggregates are exposed, being characterized by that a skid resistance value C.S.R.B. (JIS A 5705 and JIS A 1454 are referenced) is 1.4 or more at awetting face forabarefoot and anon slippery artificial stone characterized by that a skid resistance value C.S.R.B.

is 0.8 or more at a wetting face with soap for a barefoot; and a non slippery artificial stone including an inorganic aggregate anda resinandhavinga convexoconcave surface inwhich inorganic aggregates are exposed, being characterized by that a surface contactangle ofdistilledwater is45 A scraped amount from the surface of the artificial stone by water-jet machining is about 10 cm 3 /m 2 from a view point of a surface concave groove depth of 0.02 to 1.0 mm as a general rule of thumb, while it varies depending upon a sort of inorganic aggregate and resin, their composition rate, and the formation condition, and is decidedappropriately considering thesepoints.

In a case of the artificial stone with a use of quartz as an inorganic aggregate and MMA resin, for instance, the measure can be 30 to 38 cm 3 /m 2 for the average surface concave groove depth of 0.05 mm and 80 to 92 cm 3 /m 2 for the average surface concave groove depth of 0.2 mm.

An effluent treatment for water-jet machining is easy in comparison with an etching method which employs an organic solvent.

Of course, parts of the surface can be removed, if needed, bymeans of processing inanorganic solvent, softening ormelting a resin component.

The organic solvent used in the above purpose maybe selected in correspondence with a resin component. It includes, for instance, a halogenated hydrocarbon such as ethylene chloride, dichloromethane, and chloroform; carboxylic acid and the ester S 10 compound such as acetic acid anhydride, ethyl acetate, and butyl ooooo: acetate; or acetone, tetrahydrofuran, DMF, and DMSO.

Convexoconcaves on the surface of the artificial stone compact can be formed by means of removing a softened or melted resin component from the surface after dipping the compact in 15 these organic solvent or spraying or flowing these organic solvents on the compact.

The softened resin component may be scraped off from the surface with a wire brush or other scraping means.

*000 ~In addition, particles may be exposed to the surface of the product as sections by means of grinding the surface and as the result, breaking the surface partially. Surface texture with unique depth, luster, and gloss are realized hereby. This is caused by a unique phenomenon of reflected light.

A means for surface polishing is not limited in particular.

It can be carried out with a tool such as a grind stone, an abrasive cloth, and an abrasive belt, or an abrasive such as a buffing compound and a rubbing compound.

42 As abrasives, the following may be appropriately employed; diamond, boron carbide, corundum, alumina, and zirconia for mainly grinding, and tripoli, dolomite, alumina, chromium oxide, and cerium oxide for mainly polishing.

The surface can be roughened, after being polished in the above method.

The noctilucent/luminescent artificial stone product suited for various uses which includes products with or without non-slipperiness, can be provided by various manufacturing methods such as various forming methods, or various processing methods like cutting, scraping, laminating, and etching.

Various members and formations, for instance, for decorations for the night, buildings and public works such as direction indicators and guides for location by luminescence in a dark atmosphere, and disaster prevention, can be provided. It is needless to say that the above products are utilised as a luminescent member or an optical formation for using no energy or saving energy.

By the way, there are several points which should be paid attention to, in relation to the present invention.

i ~It is noted that the following products may be provided as embodiments of noctilucent/luminescent artificial stone of the present invention; a product, for instance, as is shown in Fig. 1, consisting of the cut out artificial stone (12) as a thinner board than the molded board from the molded artificial stone (11) after cast and hardened; or the artificial stone (13) which was further processed on the artificial stone (12).

o*o In addition, it is natural, but it is needless to say that a cut out artificial stone (15) in a sheet form from an artificial stone (14) which was carried out with ooo° non slip processing on the molded artificial stone (11) as is shown in Fig. 1, may also be provided as an artificial stone of the present invention.

H: \IsabelH\Speci\43583.doc 9/06/06 43 The present invention also provides a formation in which the noctilucent/luminescent artificial stone is laminated as a surface material, or a formation in which the noctilucent/luminescent artificial stone is composed as a part of the surface.

As for a lamination composition, an integrated body is illustrated, which is composed of; the noctilucent/luminescent artificial stone in accordance with an embodiment of the present invention as a surface material; and a resin plate, a metal plate, a stone, a ceramic plate or a cement plate on the back, which is laminated with an adhesive, or bonded mechanically with metal fittings or fit bonds.

The following are also illustrated; an integrated product in which a noctilucent/luminescent stone which is an embodiment of the present invention is composed with an inorganic material such as a mortar concrete or a gypsum, or a resin as a backing material by means of casting and molding after the artificial stone was cast and hardened or semi-hardened; a product obtained by placing a tile, a gypsum plate, a metal plate, and glass at a predetermined site and casting and hardening the artificial stone; and a i product obtained by molding an artificial stone which is an embodiment of the present invention, and in the semi- 25 hardened condition on the back side, placing a tile, a gypsum plate, a metal plate, and glass at a predetermined site, and hardening it with compression.

The following various products, as are shown in Fig. 2 for instance, may be included in the laminated composition; not only a product in which the noctilucent/luminescent artificial stone of the present invention (21) is entirely laminated with other sort of materials but also a product partly laminated in a grating shape like Fig. 2 and a product laminated in 35 a multi layer.

In addition, as for a product a part of which the noctilucent/luminescent artificial stone composes, the H:\IBabe1H\Speci\43583.dc 9/06/06 44 following appropriate constitutions are to be considered; a product in which the artificial stone similar to the noctilucent/luminescent artificial stone is placed through joints; a product in which the noctilucent/luminescent artificial stone (31) is arranged as a part of steps of a flight of stairs as is shown in Fig. 3; a product as is shown in fig. 4 in which an artificial stone, concrete materials, tile materials or the like without luminescence is molded with implantation in a predetermined place of the noctilucent/luminescent artificial stone (41) of the present invention as a base material.

As described in detail in the above, in the present invention, the improvement of the luminescence performance such as a longer continuation time of a light accumulation luminescence is enabled, and besides giving physical properties of extremely high and functional qualities such as strength, surface hardness, abrasion resistance, weatherability, and non-slipperiness are also enabled by a control of the structure of the artificial stone.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, ie. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It is to be clearly understood that although prior art publication(s) are referred to herein, this reference does not constitute an admission that any of these documents forms part of the common general knowledge in the art in Australia or in any other country.

H:\IsabelH\Speci\43583.doc 9/06/06

Claims (14)

1. An artificial stone, comprising: a transparent aggregate selected from the group consisting of quartz, silica rock, rock crystal, glass, and silica; at least one kind of a light accumulation material and a luminescent material by ultraviolet rays selected from the group consisting of a strontium aluminate base substance and a zinc sulphide base substance; and a resin; wherein: the transparent aggregate has a particle diameter of 0.1 mm or more and 2/3 or less of a thick of the artificial stone once cast and hardened, and is present in a volume ratio of 49 or more and 70 or less, the resin is present in a volume ratio of 30 or more and 51 or less, the light accumulation material and/or the luminescent material by ultraviolet rays has an average particle diameter of 10 upm or more and 300 pm or less, and is present in a volume ratio of 15.61 or less, and no substantial amount of a non-transparent aggregate of larger than 0.1 mm in particle diameter is ~included; and wherein luminescence performance of the artificial stone is higher than that of the included light accumulation material and/or luminescent material by 30 ultraviolet rays per se. 6* 00go

2. The artificial stone according to claim 1, being characterised by having high luminescence 00*o0 performance in a lower filling factor (vol%) of the 35 artificial stone than a maximum filling factor (vol%) of the included light accumulation material and/or luminescent material by ultraviolet rays per se. H:\XsabeIH\Speci\43S83.doc 9/06/06 46

3. The artificial stone according to either preceding claim, wherein the particle diameter of the transparent aggregate is 0.3 mm or more.

4. The artificial stone according to any preceding claim, wherein an average particle diameter of the transparent aggregate is 1/20 or more and 1/3 or less of the thickness of the cast and hardened artificial stone.

The artificial stone according to any preceding claim, wherein the transparent aggregate particles have an irregular surface configuration.

6. The artificial stone according to any preceding claim, wherein the average particle diameter of the light accumulation material and/or the luminescent material is 40 pm or more and 150 pm or less. ooooo S

7. The artificial stone according to any preceding claim, further comprising an inorganic filler with a particle diameter less than 0.1 mm.

8. The artificial stone according to claim 7, wherein an average particle diameter of the inorganic e filler is 30 pm or more and 70 pm or less.

9. The artificial stone according to either of 30 claims 7 or 8, wherein a volume ratio of the filler to the light accumulation material, the luminescent material by ultraviolet rays or the mixture of the both, is 0 or more and 100 or less, defined as filler/light accumulation material and/or luminescent material by ultraviolet rays.

The artificial stone according to any one H: \IsabeIH\Speci\43583.doc 9/06/06 47 of claims 7 to 9, wherein the transparent aggregate is quartz or rock crystal and the filler is aluminium hydroxide or silica.

11. The artificial stone according to any one of claims 7 to 9, wherein the transparent aggregate is glass and the filler is silica or aluminium hydroxide.

12. The artificial stone according to any preceding claim, wherein a time from a saturated state after irradiation at 200 Lx with a D65 commonly used light source to brightness of 3 mcd/m 2 is 12 hours or longer.

13. The artificial stone according to any preceding claim, wherein the artificial stone is constituted with lamination as a surface material.

14. The artificial stone according to any i preceding claim, wherein the artificial stone is constituted as a part of a surface. An artificial stone substantially as hereinbefore described with reference to and as shown in *oo the accompanying drawings. *O o *go• *oo *•go *•g *oo o oo oooo *oooo H: \Iabe1H\Speci\43583.doc 9/06/06