JP2014024877A - Method for producing retroreflective solid marking material, retroreflective solid marking material and writing utensil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a retroreflective solid marking material which is provided with discriminability due to a retroreflective ability and practicability as a solid marking material, and to provide the solid marking material and a writing utensil.SOLUTION: The method for producing a retroreflective solid marking material includes: a mixing step to mix a raw material containing water, a glass bead, a binder, a surfactant, grease, and calcined gypsum with a predetermined ratio as essential components; a molding step to mold the raw material mixture obtained in the mixing step; and a baking step to heat-treat the molded product obtained in the molding step. The retroreflective solid marking material is obtained by the producing method, and the writing utensil is composed of the retroreflective solid marking material and a holder to store the same.

Description

  The present invention relates to a production method for producing a solid marking material having retroreflectivity, and a retroreflective solid marking material and a writing article obtained thereby.

Conventionally, in a marking choke used for road surface display, an attempt has been made to give reflectivity to the marking choke in order to improve visibility at night.
That is, in a method of manufacturing a marking chalk by heating and dissolving a mixed sample such as paraffin wax, petroleum oil, titanium oxide, calcium carbonate, etc., adding spherical glass fine particles, stirring and mixing and cooling and solidifying into an arbitrary shape A manufacturing method of a marking choke characterized by the above is known (see Patent Document 1).
According to this manufacturing method, the reflection efficiency of the chalk is increased, the lines and symbols displayed on the road surface are clearly reflected, so that the visual effect at night is particularly good, and the photograph of the actual situation is also good, It is said that there is a specificity that can accurately grasp the actual situation.

JP-A-3-277594

  However, the marking chalk obtained using the technique of Patent Document 1 is not made of gypsum, and conventionally, there is no solid marking material made of gypsum and having retroreflectivity. Furthermore, in order to obtain such a retroreflective solid marking material, any composition as a raw material can be used, so that the retroreflective solid marking can be distinguished by retroreflective properties and practical as a solid marking material. Whether the material can be provided is completely unknown and has not even been considered.

  Therefore, the present invention provides a method for producing a retroreflective solid marking material that has not only a color identification but also a recognizability by retroreflectivity, and also has practicality as a solid marking material, and the retroreflective property obtained thereby. The object is to provide a solid marking material and a writing article.

The present inventor has intensively studied to solve the above problems.
In the process, first, when mixing calcined gypsum and water, it was decided to produce a retroreflective solid marking material by adding glass beads, but in this case, it was broken by blending other components called glass beads. Solid marking materials, such as problems that the solid marking materials easily break down due to their ease of use or decrease in adhesion, or the solid marking materials do not adhere sufficiently to the application surface (concrete surface, paper surface, etc.) As a result, it was found that the practicality of the product was hindered.

  In this regard, increasing the blend of calcined gypsum to ensure the resistance to breakage will impair retroreflective properties and adhesion, and increasing the blend of water to ensure adhesion will tend to break. I found out that

  As a result of further studies, in order to fully develop the retroreflective properties of the glass beads and to demonstrate the practicality as a solid marking material, it is necessary to specify binders, surfactants, and spreading agents. These components were also used together, and it was found that it was important to use these raw materials in a specific ratio, and the present invention was completed.

  That is, the method for producing a retroreflective solid marking material according to the present invention comprises 1 to 40% by weight of water, 30 to 75% by weight of glass beads, 0.1 to 2.5% by weight of a binder, 0.1 to 0.1% of a surfactant. 10% by weight, a mixing step of mixing raw materials essential to 0.1 to 10% by weight of spreading agent and 5 to 20% by weight of calcined gypsum, a forming step of forming the raw material mixture obtained in the mixing step, And a firing step of heat-treating the molded product obtained in the molding step.

  Moreover, the retroreflective solid marking material concerning this invention is a thing obtained by the said manufacturing method, It is characterized by the above-mentioned.

  Furthermore, the writing article according to the present invention is characterized by comprising the above retroreflective solid marking material and a holder for housing the same.

  According to the present invention, a retroreflective solid marking material that exhibits sufficient retroreflectivity due to the blending of glass beads and also has practicality as a solid marking material and a writing article using the same can be obtained. .

Hereinafter, the retroreflective solid marking material according to the present invention, its manufacturing method and writing articles will be described in detail with particular focus on the manufacturing method, but the scope of the present invention is not limited to these descriptions, Other than the above examples, modifications can be made as appropriate without departing from the spirit of the present invention.
First, after describing each component used as a raw material in detail, each process of a manufacturing method is explained in full detail.

〔material〕
As raw materials used in the method for producing a retroreflective solid marking material according to the present invention, water, glass beads, a binder, a surfactant, a spreading agent, and calcined gypsum are essential.

<Water>
When water is mixed with calcined gypsum, it can react with calcined gypsum and solidify it. From the viewpoint of performing homogeneous mixing with other components, for example, it is preferably used as room temperature water of about 20 ± 15 ° C.

<Glass beads>
The glass beads have a function of refracting incident light within the glass beads to focus on the spherical surface of the glass beads and recurring them as reflected light.
In the present invention, since the glass beads are blended, a solid marking material having retroreflectivity can be manufactured.

  As the glass beads, ideally spherical ones are used, but practically sufficient retroreflective properties can be exhibited as long as they have a sphericity that is industrially obtained.

  Depending on the refractive index of the glass beads, the refractive action of incident light and reflected light changes. In order to improve the retroreflectivity, those having a refractive index of 1.5 to 2.2 are preferable, and those having a refractive index of 1.8 to 2.0 are more preferable. More preferably, the refractive index is 1.92 ± 0.02. If the refractive index of the glass beads is less than 1.5, the direction of the reflected light may be significantly shifted due to the low refractive index and the visibility may be significantly reduced. There is a risk that the visibility may be lost due to slippage.

  Further, the smaller the particle size of the glass beads, the easier it is to write a solid marking material, and the glass beads are more likely to adhere to the surface to be applied, so that high retroreflectivity tends to be obtained. For these reasons, the particle size is preferably 75 μm or less, and more preferably 45 μm or less.

  The glass beads are preferably excellent in transparency. However, translucent glass beads colored so thin as not to impair the retroreflective property can also be used. In the present invention, the glass beads include translucent glass beads.

As a glass bead, if a self-reflective bead provided with a reflective film by depositing metal, oxide, fluoride, etc. on a part of the surface, for example, about the hemispherical part of the glass bead, the light incident on the glass bead is By reflecting on the inner surface of the reflective film, the retroreflection efficiency can be increased.
Examples of such a deposition material include metals such as aluminum, chromium, zinc, gold, silver, platinum, and nickel, metal oxides such as silicon oxide, titanium oxide, and zirconium oxide, and fluorides such as magnesium fluoride. Is mentioned.

  As a method for improving the retroreflective efficiency, in addition to using the self-reflective beads as described above, a method of using a reflective material such as mica as a raw material as described later is also preferable.

<Binder>
By blending a binder, the solid marking material can be given strength and easily broken.
By using a thermosetting resin as the binder, the binder is cured in the baking step described later, and the above-described reinforcing effect is exhibited extremely well.

  Examples of the thermosetting resin preferable as the binder of the present invention include phenol resin, melamine resin, urea resin, alkyd resin, epoxy resin, unsaturated polyester resin, polyurethane resin, thermosetting polyimide, and the like.

<Surfactant>
By blending the surfactant, the adhesion of the glass beads to the applied surface is improved when the obtained solid marking material is applied to the applied surface such as concrete. In addition, since it has the ability to emulsify and disperse the spreading agent and pigment described later, it is excellent in dispersion stability in an aqueous system, and is easily mixed with moisture, thereby improving the workability during molding.

The surfactant is not particularly limited, and any of an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant may be used. For example, it is preferable to use a material that does not easily deteriorate even under heating at about 180 ° C., because the effect of addition is not hindered even under high-temperature conditions in the firing step.
Of these, nonionic surfactants are preferred. Although not specifically limited, for example, ester type, ether type, ester / ether type, alkylamine EO adduct, and the like can be used, and these can be used alone or in combination of two or more.

  Examples of commercially available products include “Solsperse 27000” (manufactured by Nippon Lubrizol Co., Ltd.) as a nonionic surfactant.

<Spreading agent>
The spreading agent is relatively stable even at high temperatures, and is present in a viscous state without evaporating from the raw material mixture in the firing process described later. When drawing letters and figures on the application surface, it plays a role to prevent the glass beads from falling off the application surface.

  Examples of the spreading agent include greases containing oils, thickeners, additives, etc., and metal soap base greases, silicon greases, fluoroether greases, aqueous greases and the like are particularly preferable. Can be used alone or in combination of two or more. Among them, if an excellent heat resistance, for example, a material that does not easily deteriorate even under heating at about 180 ° C., the effect of addition is not hindered even under high temperature conditions in the firing step. preferable.

  Commercially available products include, for example, silicon compound (manufactured by Dow Corning Toray), G-40 grease for high temperature lubrication (manufactured by Shin-Etsu Chemical Co., Ltd.), TSK series, YG series (both Momentive Performance Materials Japan ( (Made by former GE Toshiba) etc.), and these can be used alone or in combination of two or more.

<Gypsum>
For calcined gypsum, raw gypsum such as chemical gypsum and natural gypsum is calcined, and raw gypsum that is mainly dihydrate gypsum (CaSO ₄ · 2H ₂ O) is mainly used as hemihydrate gypsum (CaSO ₄ · 1 / 2H ₂ O). ).

  The calcined gypsum obtained as described above has the property of rapidly solidifying as a dihydrate when added to a slurry with an appropriate amount of water, and solid marking materials using calcined gypsum generally have this property. Manufactured using the principle.

  It does not specifically limit as a kind of calcined gypsum applied to this invention, A well-known thing can be used as calcined gypsum for solid marking materials. For example, if it is a commercial item, the calcined gypsum class B by the Yoshino gypsum company, (beta) type | mold hemihydrate gypsum etc. are mentioned preferably, These can be used combining 1 type (s) or 2 or more types.

<Other ingredients>
As a raw material in the manufacturing method of the retroreflective solid marking material of this invention, as long as the effect of this invention is not impaired, you may use another component other than said each component.

  For example, by blending a hydration reaction retarder, solidification due to the reaction of calcined gypsum and water can be delayed, and the workability in the work of mixing each component, the work of pouring the raw material mixture into a mold, and the like is improved.

  The hydration reaction retarder is not particularly limited, and examples thereof include polyhydric alcohols such as glycerin and isopropyl alcohol, carboxylic acids such as citric acid and gluconic acid, salts thereof, polyhydric alcohol fatty acid esters, and the like. These may be used, and these may be used alone or in combination of two or more. Of these, sodium citrate is preferably used.

  Further, for example, a retroreflective solid marking material having a desired color can be provided by adding a pigment. Any pigment may be used as long as it is a water dispersion type pigment.

  Furthermore, retroreflectivity can be improved by adding a reflective material. In particular, when normal glass beads are used as the glass beads instead of the above-described self-reflecting beads, it is effective to increase the retroreflectivity by using a reflecting material.

  Examples of the reflective material include fine scales, particles, fibers, and the like, and the particle size can be set to, for example, 1.0 to 50 μm.

  As a specific material of the reflecting material, mica is preferably mentioned. Mica is processed into a thin scale using mica as a raw material, and its reflected light is generally white. When the mica surface is coated with titanium oxide, the reflection performance is enhanced. As the reflecting material, a metal having surface reflectivity such as aluminum, an inorganic material, a mineral, or the like can be used. If the reflecting material is colored, the coloring function can be exhibited in addition to the reflecting function. For example, aluminum particles emit silvery reflected light. The colored aluminum particles emit reflected light of the colored color. Non-leafing type aluminum particles are less susceptible to surface oxidation, can maintain good reflectivity, and are suitable for use.

[Method for producing retroreflective solid marking material]
The manufacturing method of the retroreflective solid marking material of the present invention includes a mixing step of mixing the raw materials described above, a molding step of molding the raw material mixture obtained in the mixing step, and a molded product obtained in the molding step. A firing step of firing.

<Mixing process>
The mixing step is a step of mixing the raw materials described above, but according to the experimental verification of the present inventors, in order to obtain the excellent effect of the present invention, the mixing and blending of each component in the raw material mixture is as follows. It must be in range.

  The mixing ratio of water is 1 to 40% by weight. It is preferably 5 to 25% by weight. If it is less than 1% by weight, the raw material mixture becomes highly viscous and difficult to mix uniformly, and if it exceeds 40% by weight, it becomes a solid marking material that is easy to break.

  The mixing ratio of the glass beads is 30 to 75% by weight. It is preferable that it is 60 to 70 weight%. If it is less than 30% by weight, the retroreflective property cannot be sufficiently imparted, and if it exceeds 75% by weight, the practicality as a solid marking material is impaired.

  The mixing ratio of the binder is 0.1 to 2.5% by weight. It is preferably 0.8 to 1.6% by weight. If it is less than 0.1% by weight, the strength as a solid marking material is insufficient, and if it exceeds 2.5% by weight, it is too hard to slip and difficult to write. The binder mixing ratio here refers to a value based on the weight of the solid content.

  The mixing ratio of the surfactant is 0.1 to 10% by weight. It is preferably 0.3 to 1.0% by weight. If it is less than 0.1% by weight, the adhesive agent is not sufficiently emulsified / dispersed and the adhesion to the glass beads is reduced, causing the glass beads to fall off. The ratio decreases and the retroreflectivity decreases.

  The mixing ratio of the spreading agent is 0.1 to 10% by weight. It is preferably 0.5 to 3.5% by weight. If it is less than 0.1% by weight, the effect of adding the spreading agent described above cannot be obtained sufficiently, and the retroreflective effect becomes uneven. On the other hand, when it exceeds 10% by weight, the spreader is excessively attached around the glass beads and the retroreflectivity is lowered.

  The mixing ratio of calcined gypsum is 5 to 40% by weight. It is preferably 8 to 15% by weight. If it is less than 5% by weight, sufficient strength cannot be obtained in the molding process described later, and molding processing becomes difficult. If it exceeds 40% by weight, the proportion of glass beads is relatively small, and sufficient retroreflectivity cannot be obtained. .

When mixing a hydration retardant, the mixing ratio varies depending on the type of hydration retardant used, but basically the mixing ratio is sufficient to obtain a hydration retardant effect. That's fine.
For example, the mixing ratio in the case of using a carboxylic acid such as citric acid or gluconic acid or a salt thereof as the hydration reaction retarder is preferably 0.01 to 0.5% by weight, More preferably, it is 0.1% by weight. If it is less than 0.01% by weight, the above-mentioned hydration reaction retarding effect may not be sufficiently obtained, and if it exceeds 0.5% by weight, the solid marking material is difficult to solidify and may be easily broken.
Further, the mixing ratio in the case of using a polyhydric alcohol such as glycerin or isopropyl alcohol or a polyhydric alcohol fatty acid ester as the hydration reaction retarder is preferably 1 to 10% by weight, and 2 to 5% by weight. It is more preferable that If it is less than 1% by weight, the effect of delaying the hydration reaction may not be sufficiently obtained. If it exceeds 10% by weight, the solid marking material may be difficult to solidify and may be easily broken.

  In the mixing step, water, glass beads, binder, surfactant, spreading agent, and other additives as necessary are mixed to prepare an aqueous composition, and this aqueous composition is mixed with calcined gypsum. It is preferable. Thus, before water and calcined gypsum are mixed and solidification occurs, by preparing an aqueous composition, it is possible to obtain a mixture in which each component is homogeneously mixed.

  In particular, after adding other components such as binder, surfactant, and spreading agent to the glass beads, as well as other hydration retarders, pigments, and reflectors, if necessary, add water, and finally It is preferable to carry out in the order of adding calcined gypsum.

  As can be seen from the reasons described above, it is preferable to sufficiently stir and mix after preparing the aqueous composition and before mixing with calcined gypsum. It is preferable to gently stir after adding calcined gypsum to the aqueous composition.

<Molding process>
A molding process is performed after a mixing process.
Specifically, for example, the raw material mixture obtained in the mixing step is poured into a predetermined mold while stirring.
In this case, the mold may be appropriately selected according to the shape of the solid marking material to be finally produced. Although not particularly limited, generally, a cylindrical shape or a similar shape is adopted as the shape of the solid marking material. In order to ensure that it is not easily broken and easy to write, a cylindrical shape having a diameter of 1 to 1.5 cm and a length of 8 to 15 cm is preferable.

  After pouring the raw material mixture into the mold, it is preferable to perform demolding after a lapse of strength until a strength that can be taken out from the mold is obtained.

<Baking process>
By performing the firing step after the molding step, the water content of the solid marking material is sufficiently removed, and the mixed components are solidified integrally, thereby exhibiting the difficulty of breaking and moderate brittleness for writing.

  This firing step is preferably performed by heat-treating the material taken out of the mold in the molding step at 110 to 180 ° C. for 1 to 5 hours, and heat treatment at 160 to 180 ° C. for 3 to 4 hours. More preferably.

[Examples of using retroreflective solid marking material]
The retroreflective solid marking material obtained by the production method of the present invention has retroreflectiveness and practicality comparable to a conventionally known solid marking material. As with known solid marking materials, it is extensive.

  For example, the object to which the retroreflective solid marking material can be applied is not particularly limited, such as concrete, asphalt, metal, wood, paper, and the like. More specific usage scenes include marking on building materials and foundations in civil engineering and construction sites, marking on road surfaces, etc. for police identification, writing on blackboards in educational sites, and so on.

  As a particularly preferable application example, there is application as a marking chalk in a civil engineering / construction site.

  For example, in scenes such as maintenance of highways, crack repair of concrete structures is one of the important daily inspection items from the viewpoint of preventing serious accidents. In this case, the part containing cracks (cracks) is traced with a solid marking material, the photograph is taken by marking, and the photograph data is analyzed, but the retroreflective property obtained based on the present invention is performed. According to the solid marking material, the marking portion can be easily identified by using the retroreflective property. In particular, the marking portion is retroreflected and imaged by light irradiation using flash photography or the like. Can be obtained very easily.

By the way, in concrete structures inside and outside the tunnel under the use of sodium lighting, it is extremely difficult to determine the color with the naked eye.
And, as described above, when applying the retroreflective solid marking material of the present invention to highway maintenance and the like, when considering application to concrete structures inside and outside the tunnel in use under sodium illumination, With this retroreflected light, it may be difficult to distinguish the marking portion with the retroreflected light.
Therefore, if a specific pigment that can be identified even under a spectrum unique to a sodium lamp is used as a production raw material for the retroreflective marking material of the present invention, the specific pigment appears as retroreflected light. Thus, it is possible to easily perform the color determination even under the spectrum specific to the sodium lamp.
As described above, according to the retroreflective solid marking material of the present invention, it is possible to improve the difficulty of color determination under a special condition of using sodium illumination.

In addition, when taking photographs under the sunlight when investigating and inspecting concrete structures in the field, sunlight produces extreme shade and shade of light, and conventional marking chalks can distinguish colors. It was particularly difficult.
However, according to the retroreflective solid marking material of the present invention, difficulties that cannot be achieved by conventional marking can be solved by retroreflectivity. In particular, by increasing the content of glass beads that exhibit retroreflectivity, it is possible to easily take a photograph.

The retroreflective marking material of the present invention is equivalent to the hardness of a conventional general marking choke or, in some cases, exhibits a hardness exceeding that of a conventional general marking choke. There are few. Therefore, the use on the uneven surface of a concrete structure such as an expressway is not hindered.
In particular, by increasing the diameter to about 1.5 cm, problems such as breakage and solid material consumption are more appropriately solved.

  The retroreflective solid marking material of the present invention may be applied as it is to the above various uses, but may be used as a writing article stored in a holder. According to this, since the writer can write and carry without directly touching the solid marking material, there is an advantage that the hand is not dirty, and an advantage that the solid marking material can be prevented from being broken or damaged. It is done.

  Hereinafter, although the manufacturing method of the retroreflective solid marking material concerning this invention is demonstrated in detail using an Example, this invention is not limited to these Examples. Hereinafter, for convenience, “% by weight” is simply expressed as “%”.

Each solid marking material of Examples 1-11 and Comparative Examples 1-7 was prepared with the prescription shown in the following Tables 1 and 2.
Specifically, first, an aqueous composition was prepared by mixing raw materials other than calcined gypsum. Thereafter, calcined gypsum was added, and this raw material mixture was slowly poured into a mold. After 1 hour from pouring into the mold, the mold was removed and heat treatment was performed at 180 ° C. for 3 hours.
In this manner, a cylindrical chalk having a diameter of 11 cm and a length of 8 cm was produced as each solid marking material.

In the said Table 1, 2, each raw material is as follows.
<Glass beads>
Glass beads 1: “Unibeads 24MSJ” (38-45 μm aluminum vapor-deposited glass beads, manufactured by Union Co., Ltd.)
Glass beads 2: “HI-25-44G” (25-44 μm glass beads, refractive index 1.93, manufactured by Nippon Electric Glass Co., Ltd.)
<Binder>
"Beccamin APM" (thermosetting melanin resin, manufactured by Kita Nippon Polymer Co., Ltd.)
<Surfactant>
"Solsperse 27000" (nonionic surfactant, manufactured by Nippon Lubrizol Co., Ltd.)
<Spreading agent>
“DOW CORNING TORAY SH111 COMPOUND” (silicone grease, manufactured by Toray Dow Corning Co., Ltd.)
<Gypsum>
Calcined gypsum 1: "Gypsum-gypsum class B" (gypsum, manufactured by Yoshino Gypsum Co., Ltd.)
Calcined gypsum 2: “High Stone N” (calcined gypsum, manufactured by Yoshino Gypsum Co., Ltd.)
<Reflecting material>
"A-903D" (synthetic mica, manufactured by CQV)
<Hydration retardant>
Hydration reaction retarder 1: “Purified glycerin” (manufactured by Shoei Pharmaceutical Co., Ltd.)
Hydration reaction retarder 2: Sodium citrate aqueous solution (0.02%)
<Pigment>
"Ryudye W GREEN FBK" (Dainippon Chemical Industry Co., Ltd.)
<Spreading aid>
"VS16H3" (made by Kitahiro Chemical Co., Ltd.)

[Performance evaluation]
The following physical properties of these solid marking materials were evaluated. The results of performance evaluation are also shown in Tables 1 and 2.
<Retroreflective performance>
◎… Retro-reflective performance is large ○… Retro-reflective performance is moderate ×… Retro-reflective performance is scarce XX… Retro-reflective performance is completely absent

<Mura>
◎ ... Reflected uniformly without unevenness ○: Unevenness is hardly seen ×: Finished with unevenness XX: Unevenly reflected and not uniformly reflected

<Workability>
◎… Good workability ○… Can work without problems ×… Difficult to work ××… Cannot work smoothly

<Adhesiveness>
◎ Even if a strong impact or vibration is given in the state depicted on the wall, the glass beads do not fall off and there is reflection ○ ... Even if a light impact or vibration is given in the state depicted on the wall, the glass beads do not fall off and reflect Yes ... The glass beads fall off when light impact or vibration is given in the state depicted on the wall, and there is almost no reflection. XX ... The glass beads fall off when slight impact or vibration is given in the state depicted on the wall. No reflection

<Difficult to break>
◎… Folds when depicted strongly on the wall ○… Folds when depicted with moderate force on the wall ×: Folds when depicted lightly on the wall ××… Folds when strongly held with chalk

[Consideration of results]
As a result, good results could be obtained in Examples 1 to 11. In Comparative Examples 1-7, it was judged that it was unsuitable for a solid marking material from the following problem.

In Comparative Example 1, there was a defect that the hardness was low due to the absence of the binder, and it was easy to break when compared with ordinary chalk.
In Comparative Example 2, since the binder is contained in a large amount, the solid marking material becomes hard after heat treatment, and it is difficult to draw on the display object, and the marking material itself appears on the surface at the time of drawing to drop the glass beads, so the brightness is low. became.

In Comparative Example 3, since no spreading agent was added, the adhesiveness was weak, and when a strong vibration was applied several times, the glass beads dropped out when written on the wall surface.
In Comparative Example 4, since a large amount of spreading agent was contained, the spreading agent covered the surface of the glass beads, the luminance was low, and sufficient performance could not be obtained.

In Comparative Example 5, since the surfactant was not contained, the spreading agent was not sufficiently dispersed, the stirring was very poor, and it was difficult to obtain uniform dispersion.
In Comparative Example 6, since a large amount of the surfactant was contained, even when heat treatment was performed, the solid marking material was in a wet state, the luminance was low, and luminance unevenness occurred.

  In Comparative Example 7, since a large amount of spreading aid (those that enhance spreading ability) was added without using water, the spreading aid did not fly even after heat treatment, and the wet state In order to maintain the brightness, the brightness was low and uneven brightness was observed.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used as a method for producing an excellent retroreflective solid marking material that can be used for various uses as a solid marking material while having retroreflectivity.

Claims (9)

  1-40 wt% water, 30-75 wt% glass beads, 0.1-2.5 wt% binder, 0.1-10 wt% surfactant, 0.1-10 wt% spreading agent and calcined gypsum A mixing step of mixing the raw materials essential to 5 to 20% by weight, a forming step of forming the raw material mixture obtained in the mixing step, and a firing step of heat-treating the molded product obtained in the forming step A method for producing a retroreflective solid marking material.   The manufacturing method of the retroreflective solid marking material of Claim 1 which mixes a hydration reaction retarder further in the said mixing process.   The method for producing a retroreflective solid marking material according to claim 1 or 2, wherein a self-reflective bead in which a vapor deposition layer made of aluminum metal is formed on the hemisphere portion is used as the glass bead.   The said glass bead is a manufacturing method of the retroreflective solid marking material in any one of Claim 1 to 3 which is a spherical shape with a particle size of 75 micrometers or less and a refractive index of 1.5-2.2.   In the mixing step, after preparing an aqueous composition containing water, glass beads, a binder, a surfactant and a spreading agent, the aqueous composition and calcined gypsum are mixed. The manufacturing method of the retroreflective solid marking material in any one of.   The manufacturing method of the retroreflective solid marking material in any one of Claim 1-5 which performs the said baking process by heat processing for 1 to 5 hours at 110-180 degreeC.   The method for producing a retroreflective solid marking material according to any one of claims 1 to 6, wherein a pigment is further mixed in the mixing step.   A solid marking material obtained by the production method according to claim 1.   A writing article comprising the solid marking material according to claim 8 in a holder.