JP6275509B2 - Marker board and manufacturing method thereof - Google Patents

Description

  The present invention relates to a marker board formed with a ridge layer on the surface of a substrate, and particularly when a video such as a character is projected using a short focus type projector or the like, an image such as a character can be projected clearly. The present invention relates to a marker board having both a reflective screen function and an excellent marker character erasability that can easily erase characters drawn with a marker.

  Recently, in various lectures, lectures, explanations, etc., it is common to use various projectors such as slides, OHP, etc., to project materials prepared in advance on the screen and to explain while pointing with a pointing stick etc. However, in many cases, a marker board is used as an aid in addition to the screen. Therefore, it has a marker board function that can draw characters, images, etc. on the surface in an erasable manner with a marker and also has a screen function that can project images with various projectors, or a screen function and a marker board function. Proposed screens have been proposed.

  For example, Patent Document 1 proposes an enamel marker / screen board characterized in that an enamel layer having a surface gloss Gs (45 °) in the range of 30 to 60% is formed on a substrate. ing. According to the technique described in Patent Document 1, the smoothness required for the marker board, the brightness and the reflection luminance required for the projection screen are good, the drawing property and erasing property by the marker are excellent, and the halation property is good. It is said that a suppressed and marker board can be obtained.

  Patent Document 2 describes a writing screen combined writing board. The technique described in Patent Document 2 is characterized in that the writing surface is provided with an antireflection layer having a glossiness of 70% or less, a haze value of 3.0% or more, and a center line roughness Ra of 1 μm or less. Thereby, it is said that it is excellent in handwriting erasability and the projected image is clear and can be used as a writing board or a screen.

  Patent Document 3 describes a reflective screen that can be drawn and erased with a marker or the like. The reflective screen described in Patent Document 3 has a surface glaze layer containing titanium oxide-coated particles and white glaze on the outer surface of a metal substrate, and the surface roughness Ra of the surface glaze layer is 1.5 μm or more and 2.5 μm. With a glossiness Gs (45 °) of 15 to 25%, the erasability of writing with markers, etc. is improved, the image is clear, and the reflection screen is improved with less halation and improved clarity. Yes.

  Patent Document 4 describes a multipurpose writing board. The multipurpose writing board described in Patent Document 4 is a writing board that has been processed to make a writing surface, the writing surface is lightly colored, and the surface roughness is set to a maximum height Ry of 4.9 to 10.5 μm. is there. As a result, it can be used as a chalk board, a marker board, and a screen.

Japanese Patent Laid-Open No. 02-153080 Japanese Unexamined Patent Publication No. 04-229299 Japanese Patent Laid-Open No. 2002-6399 JP 2008-100401

  However, the marker screen combined board described in Patent Document 1, the projection screen combined writing board described in Patent Document 2, and the multipurpose writing board described in Patent Document 4 are all provided with a character drawing property by a marker, a character Although it was excellent in erasability, it had a problem in halation suppression when used as a screen. In addition, the reflective screen described in Patent Document 3 has a surface glaze layer containing titanium oxide-coated particles and white glaze on the outer surface to improve halation suppression by diffuse reflection. Had left a problem.

Also, in the past, images were projected almost perpendicularly onto the projection surface (board surface), but recently, a short focus type projector has been developed and is projected from a relatively upper position, which is different from the conventional reflection. A screen function is required.
The present invention advantageously solves the problems of the prior art and is a marker board in which at least a surface glazing layer is formed on a substrate, and has an excellent reflective screen function (projection) even when a short focus type projector is used. It is an object of the present invention to provide a marker board having excellent marker character recognizability and excellent marker character erasability and a method for manufacturing the same.

  In order to achieve the above-mentioned object, the present inventors diligently studied various factors affecting the reflective screen property and marker character erasability of the marker board. As a result, in order to obtain a surface glazing layer having an excellent reflective screen function, excellent marker character recognition, and excellent marker character erasing property, the surface glazing layer is white based on JIS Z 8721-1993. Color tone with a specified lightness V of over 8.3 and a chroma C of 0 to 1.0, surface roughness Ra specified by JIS B 0601-2001: surface characteristics of 0.25 to 0.8 μm, and JIS Z 8741- The present inventors have conceived that it is necessary to form a glazing layer having a 45 ° specular glossiness as defined in 1997: Gs (45 °) having a surface glossiness of 35 to 85%. Such a surface glaze layer uses a glaze glaze in which at least titanium oxide-coated particles and a sulfuric acid method / anatase type non-surface-treated titanium oxide having a particle size of 0.3 μm or less are blended as a pigment with a white titanium gloss glaze. And found that it can be formed. The surface wrinkle layer thus formed has a reduced surface roughness, and in particular, the maximum height of the projections (mountains) forming the irregularities on the surface is remarkably reduced, so even if the marker characters are drawn, In addition to excellent recognizability, marker character erasability is significantly improved. At this time, it was found that an excellent reflective screen function was maintained, and that even when an image was projected by a short focus type projector, the image could be clearly recognized.

The present invention has been completed based on such findings and further studies. That is, the gist of the present invention is as follows.
(1) A marker board having at least one glazing layer on a metal substrate, wherein the outermost surface glazing layer of the glazing layer is white and has a lightness V defined by JIS Z 8721-2001 of 8.3. Super, color tone with saturation C of 0 to 1.0, surface roughness Ra specified by JIS B 0601-2001: surface characteristics of 0.25 to 0.8 μm, 45 degree specular surface specified by JIS Z 8741-1997 gloss: possess a surface gloss Gs (45 °) is 35% to 85%, the and the surface enamel layer is, the white titanium gloss glaze, following even at least titanium oxide coated particles and the particle diameter 0.3μm Marker with excellent reflex screen function, marker character recognition and marker character erasing characteristics, characterized by being a cocoon layer formed using a glaze glaze containing sulfuric acid method and anatase type non-surface-treated titanium oxide particles board.
(2 ) After applying the glaze on the surface of the metal substrate and firing to form the lower glaze layer, or without forming the glaze layer, the glaze is applied and fired to form the surface glaze layer. In the marker board manufacturing method for forming the above, the glaze glaze is further mixed with white titanium gloss glaze at least titanium oxide-coated particles and sulfuric acid method / anatase type non-surface treated titanium oxide particles having a particle size of 0.3 μm or less. A method for producing a marker board excellent in reflective screen function, marker character recognizability and marker character erasability, characterized in that the glaze is made into a glaze and the firing temperature of the surface glaze layer is set to 700 to 850 ° C.
( 3 ) In ( 2 ), the titanium oxide-coated particles are formed into flake-like particles, and the titanium oxide-coated particles are blended in an amount of 5 to 15 parts by mass with respect to 100 parts by mass of white titanium gloss glaze. A method for producing a marker board, comprising mixing 2 to 8 parts by mass of anatase-type unsurface-treated titanium oxide particles with respect to 100 parts by mass of a white titanium gloss glaze.

  According to the present invention, a marker board that has excellent image recognizability, an excellent reflective screen function, and at the same time excellent marker character recognizability and marker character erasure, particularly when projected by a short focus type projector, can be easily obtained. It can be manufactured and has a remarkable industrial effect. The present invention also has an effect that it can greatly contribute to the expansion of the use of the marker board.

  The marker board according to the present invention is a smoked marker board having at least one cocoon layer on a metal substrate. In the present invention, the type of the metal substrate to be used is not particularly limited, but is preferably a cold-rolled steel plate. The cold-rolled steel sheet used as the metal substrate is preferably subjected to Ni plating in order to improve the adhesion between the metal substrate and the glaze. Examples of the cold rolled steel sheet include a low carbon steel sheet and a stainless steel sheet. The C content of the low carbon steel plate is preferably 0.0200% or less in mass%, more preferably 0.0100% or less, and still more preferably 0.0080% or less.

Moreover, as a metal substrate, it is good also as an aluminum plating steel plate or a Zn-Al alloy plating steel plate. Examples of the Zn-Al alloy-plated steel sheet include a plated steel sheet having a plating layer comprising an Al content of 4 to 70 mass%, the balance Zn and inevitable impurities. Needless to say, the plating layer may contain an additive for improving the properties of the plating film.
Among the above-described glazing layers formed on the metal substrate, the outermost surface glazing layer is white and has a color tone with a lightness V specified by JIS Z 8721-2001 of more than 8.3 and a saturation C of 0 to 1.0. Surface roughness Ra specified in JIS B 0601-2001: Surface characteristics of 0.25 to 0.8 μm, 45 degree specular gloss specified in JIS Z 8741-1997: Gs (45 °) is 35 to 85% Surface gloss.

The lightness V in the present invention is measured according to the color measurement method defined in JIS Z 8722-2000, and is displayed according to the color display method defined in JIS Z 8721-2001. Value shall be used.
In the marker board of the present invention, the surface wrinkle layer is a white-colored wrinkle layer having a lightness V specified in JIS Z 8721-2001, exceeding 8.3, and a saturation C of 0 to 1.0. Thereby, it becomes easy to see the character, image, etc. which were drawn with the marker, and it can ensure the outstanding marker character recognizability.

  The color tone of the surface wrinkle layer was white. In a dark color tone, color reproducibility deteriorates when projected by a short focus type projector. On the other hand, when the lightness V is 8.3 or less, the characters gradually become darker and unclear, and the marker character recognizability deteriorates. For this reason, the brightness V of the surface glazing layer was limited to a range exceeding 8.3. The lightness V is preferably 9.9 or less. In addition, when the saturation C increases beyond 1.0, the color reproducibility decreases. For this reason, the saturation C of the surface wrinkle layer is limited to a range of 0 to 1.0. The saturation C is preferably 0 to 0.5.

The color tone, brightness, and saturation of the cocoon layer can be adjusted by the type and amount of the additive pigment. In order to adjust the brightness V to over 8.3 and the saturation to 0 to 1.0, black, gray, blue, brown and yellow pigments, preferably Co, Mn or their oxides alone are used as pigments. Or it is preferable to add in combination.
Further, in the marker board of the present invention, the surface wrinkle layer is a wrinkle layer having a surface characteristic of surface roughness Ra: 0.25 to 0.8 μm defined in JIS B 0601-2001. Thereby, it is possible to ensure excellent marker character recognizability and excellent marker character erasability that make it easy to write and erase characters, images and the like drawn with markers. When the surface roughness Ra is less than 0.25 μm, the surface becomes too flat, halation becomes large, and the image recognizability (projection property) of the projected image decreases. On the other hand, if the surface roughness Ra exceeds 0.8 μm, the surface irregularities become too large, and the marker character erasability deteriorates. Therefore, the surface roughness Ra of the surface wrinkle layer is limited to 0.25 to 0.8 μm. The surface roughness Ra is preferably 0.3 to 0.7 μm.

Further, the marker board of the present invention is defined by JIS Z 8741-1997, in addition to the above-mentioned color tone, the above-mentioned range of lightness, and the above-mentioned surface roughness of the surface glazing layer of the outermost layer. 45 degree specular gloss: Gs (45 °) is adjusted to 35 to 85%.
Glossiness: When Gs (45 °) is less than 35%, the halation is small and the projection property is improved, but the marker character erasability is lowered. On the other hand, when Gs (45 °) exceeds 85%, halation becomes intense, and the image recognizability deteriorates when projected by a short focus projector, and the character recognizability deteriorates due to the reflection of scenery or lighting. For this reason, the glossiness of the surface glazing layer was limited to 35 to 85% by the 45 ° specular glossiness Gs (45 °) defined in JIS Z 8741-1997.

The surface glaze layer having the above-mentioned characteristics is blended with white titanium gloss glaze (white titanium frit) or further with titanium mat glaze, and at least as an additive, fine sulfuric acid method / anatase type non-surface treated titanium oxide particles As a pigment, it is preferable to use a glaze layer formed using a glaze preferably blended with titanium oxide-coated particles. Here, the sulfuric acid method / anatase type non-surface-treated titanium oxide particles are particles having a fine particle size distribution with an average particle size of 0.3 μm or less. The “titanium oxide-coated particles” referred to here are those in which the surface of the scaly mica particles is coated with titanium oxide (TiO ₂ ) particles.

Surface enamel layer formed by using the enamel on glaze described above, in mass%, TiO _2: 5~50%, _{further, SiO 2: 0~80%, Al} 2 O 3: 0~20%, B 2 _{O 3: 0~25%, Na 2} O: 0~20%, K 2 O: 0~20%, Li 2 O: 0~20%, P 2 O 5: 0~10%, ZrO 2: 0~ It is a soot layer containing 20%, BaO: 0 to 15%, MgO: 0 to 5%, PbO: 0 to 40%, ZnO: 0 to 50%, CaF ₂ : 0 to 10%. In the present invention, the surface glaze layer is one or more selected from black pigments, gray pigments, blue pigments, yellow pigments and brown pigments in order to obtain a desired color. Needless to say, the total amount of these pigments is 10% by mass or less.

Next, a preferred method for producing the marker board of the present invention will be described.
The marker board of the present invention is obtained by applying a glaze on the surface of a metal substrate and firing to form a base glaze layer, or without forming a ground glaze layer, and then applying the glaze glaze and firing. To form a surface wrinkle layer. The type of the metal substrate to be used is not particularly limited, but is preferably a cold-rolled steel plate, an aluminum-plated steel plate, or a Zn-Al alloy-plated steel plate. When a cold-rolled steel sheet is used as the metal substrate, it is preferable to apply Ni plating to the surface of the cold-rolled steel sheet (metal substrate) after applying Ni plating to the cold-rolled steel sheet, and baked to form an undercoat layer . The agate glaze is not particularly limited, and any of the agate glazes used in conventional smoked marker boards is suitable.

As a laxative glaze, for example, it is contained by mass% with respect to the total solid content, SiO ₂ : 20 to 80%, and the balance is TiO ₂ : 0 to 15%, ZrO ₂ : 0 to 20%, B ₂ O ₃ : _{0~25%, Al 2 O 3:} 0~25%, Na 2 O: 0~20%, Li 2 O: 0~20%, K 2 O: 0~20%, PbO: 0~40%, ZnO : 0~50%, BaO: 0~15% , CaO: 0~15%, CaF 2: 0~10%, CoO: 0~20%, NiO: 0~20%, MnO: such as 0-20% It is preferable to use a ground coat glaze (ground coat frit).

After applying the above-mentioned laxative glaze to the surface of the metal substrate, it is baked at 700 to 850 ° C. to form an undercoat layer. For the application of the laxative glaze, any known application method such as spray or roll coater can be applied.
A glaze is applied to the surface of the obtained undercoat layer or the surface of the metal substrate without forming the undercoat layer, and then fired at 700 to 850 ° C. to form a overcoat layer. Any known coating method such as spray or roll coater can be applied to apply the laxative glaze.

Kajigami glaze is white titanium gloss glaze (white titanium frit), at least titanium oxide coated particles as pigment, sulfuric acid method / anatase type non-surface treated titanium oxide particles, or even white titanium matte glaze (white system) A glaze containing titanium mat frit).
As the pigment, the sulfuric acid method / anatase type non-surface-treated titanium oxide particles (TiO ₂ particles) to be blended are preferably fine particles having an average particle size of 0.3 μm or less. More preferably, the average particle size is 0.1 to 0.2 μm. As the particle diameter, a value calculated using an image analysis apparatus based on an electron micrograph is used. The sulfuric acid method / anatase type non-surface-treated titanium oxide particles (TiO ₂ particles) are blended in an amount of 2 to 8 parts by mass with respect to 100 parts by mass of the white titanium gloss glaze (white titanium frit). In addition, More preferably, it is 4-6 mass parts.
Thereby, the surface roughness becomes smooth and the marker character erasability is improved while maintaining the desired excellent reflective screen performance.

  This is because, in the glaze, the sulfuric acid method / anatase-type non-surface-treated titanium oxide particles and titanium oxide-coated particles are blended at the same time, so that the ridges of the irregularities forming the surface in the surface glaze layer after firing This is thought to be because the maximum height of (mountains) is significantly reduced. This mechanism is not clear at present, but due to the presence of sulfuric acid method / anatase type non-surface-treated titanium oxide particles, the titanium oxide-coated particles in the surface soot layer on the surface of the phosphor layer face the plate surface during firing. On the other hand, when the sulfuric acid method / anatase type non-surface-treated titanium oxide particles are not blended, it is assumed that the phosphor piece surface is easily oriented perpendicular to the plate surface.

  If the blending amount of the sulfuric acid method / anatase type non-surface-treated titanium oxide particles is less than 2 parts by mass, the above-mentioned effect due to the sulfuric acid method / anatase type non-surface-treated titanium oxide particles is small, the surface roughness Ra is increased, and the desired marker Improve character erasability. On the other hand, when the amount exceeds 8 parts by mass, there is an effect of the sulfuric acid method / anatase type non-surface-treated titanium oxide particles, but the amount of undissolved material in the glaze increases, so that the surface roughness Ra increases and is desired. Improvement of marker character erasability cannot be achieved. For this reason, the compounding quantity of the fine sulfuric acid method and anatase type unsurface-treated titanium oxide particles in the glaze glaze was limited to the range of 2 to 8 parts by mass with respect to 100 parts by mass of the white titanium gloss glaze.

In addition, as a pigment, the titanium oxide-coated particles to be blended are obtained by coating mica particles having a flake shape with titanium oxide (TiO ₂ ) particles, and 100 parts by weight of white titanium gloss glaze (white titanium frit). In contrast, 5 to 15 parts by mass are mixed. As a result, the diffuse reflection is moderately promoted, and the surface glazing layer is excellent in projection.
When the blending amount of the titanium oxide-coated particles is less than 5 parts by mass, the amount of titanium oxide-coated particles is too small and the reflection effect is diminished. On the other hand, when the amount exceeds 15 parts by mass, the surface roughness increases and the marker character erasability decreases. For this reason, the compounding quantity of the titanium oxide coating particle was limited to 5 to 15 parts by mass with respect to 100 parts by mass of the white titanium gloss glaze. More preferably, it is 8-12 mass parts.

Incidentally, the white titanium gloss glaze (white titanium frit) is a percentage by weight relative to the total solid _{content, SiO 2: 33~39%, TiO} 2: 18~24%, B 2 O 3: 9~15%, K ₂ O + Na ₂ O + Li ₂ O: 14 to 20%, Al ₂ O ₃ : 0 to 2%, P ₂ O ₅ : 0 to 4%, MgO 0 to 2%, CaO 0 to 1%, It is preferable to use a glaze containing F ₂ : 0 to 8%.
As the white titanium mat glaze (white titanium mat frit), by mass% with respect to total _{solids, SiO 2: 40~50%, TiO} 2: 18~24%, K 2 O + Na 2 O + Li 2 O: 18 containing 24%, _{further, Al 2 O 3: 0~2%} , B 2 O 3: 0~2%, ZrO 2: 0~5%, CaO: 0~1%, MgO: 0~2%, It is preferable to use a glaze containing F ₂ : 0 to 5%.

  When white titanium matte glaze (white titanium mat frit) is mixed with white titanium gloss glaze (white titanium mat frit), white titanium gloss glaze (white titanium frit) 100 It is preferable to add 0 to 50 parts by mass of white titanium mat glaze (white titanium mat frit) with respect to parts by mass. In this case, various additives and pigments are blended with the total amount of white titanium gloss glaze (white titanium mat frit) and white titanium mat glaze (white titanium mat frit) being 100 parts by mass.

  It is preferable that various additives, pigments, and water are further mixed with the above glaze and the resulting mixture is pulverized and applied to a metal substrate as a mud (slip). Depending on the color tone of the marker board, one or more pigments selected from black pigments, gray pigments, blue pigments, brown pigments and yellow pigments may be combined as pigments. It is preferable to add. The total amount of the pigment added is preferably 10 parts by mass or less with respect to 100 parts by mass of the frit (in terms of mass after firing). If it exceeds 10 parts by mass, the fluidity of the slip will decrease. For the application of the glaze glaze, any known application method such as spray or roll coater can be applied.

After the blended glaze is applied, it is baked at 700 to 850 ° C. to form a surface glaze layer.
When the firing temperature is less than 700 ° C., the surface roughness becomes too rough. On the other hand, when the temperature is higher than 850 ° C., the surface becomes too smooth, and halation is likely to occur, and the projection property (image recognition property) deteriorates.
In addition, when using an aluminum-plated steel sheet or a Zn-Al alloy-plated steel sheet as the metal substrate, a glaze is applied to the surface of the metal substrate and fired at a low firing temperature of 400 to 600 ° C. to form a surface glaze layer. It is preferable to do. In this case, it is necessary to use a low melting point glaze from the viewpoint of preventing melting of the plating layer. Even in this case, it is needless to say that fine sulfuric acid method / anatase type non-surface-treated titanium oxide particles and titanium oxide-coated particles are added to the glaze glaze.

  Hereinafter, based on an Example, this invention is demonstrated further in detail.

A low carbon cold-rolled steel sheet (KTM: plate thickness 0.35 mm × width 1190 mm) with C: 0.008% by mass was used as the metal substrate. Then, a glaze glaze (ground coat) was applied to the surface of the metal substrate with a roll coater, and then fired at 800 ° C. to form an undercoat layer having a dry thickness of 30 μm.
The glaze was used as a slip by adding clay, quartzite powder, magnesium carbonate, borax and the like to the ground coat frit and further water, mixing and pulverizing with a ball mill.

Next, after spraying glaze on one surface of the obtained undercoat layer with a spray method, it was baked at 790 ° C to form a surface coat layer (cover coat) with a dry thickness of 100 µm, and a marker board ( Product).
As glaze glaze, white titanium gloss glaze (white titanium frit) shown in Table 1 is added to 100 parts by mass (dry mass) of clay, potassium chloride and sodium aluminate as additives. Furthermore, in order to obtain the colors shown in Table 3, the total amount of the pigment is at least one selected from black pigments, gray pigments, blue pigments, brown pigments, and yellow pigments. After blending less than part, water was blended and mixed with a ball mill, powdered and used as a slip. In addition, in the surface soot layer that is an example of the present invention, 0 to 20 parts by mass of titanium oxide-coated particles are blended in addition to the pigment described above as a pigment, and the sulfuric acid method / anatase type non-surface other than the additive described above as an additive Treated titanium oxide particles (average particle size: 0.15 μm) were blended in an amount of 0 to 5 parts by mass.

  The composition of the surface soot layer of the obtained marker board (product) was investigated and shown in Table 2.

Further, the surface roughness, color tone, and glossiness of the surface marker layer of the obtained marker board (product) were investigated. The survey method was as follows.
(1) Surface roughness The surface roughness was measured using a contact-type surface roughness meter, and the arithmetic average height Ra was determined in accordance with the provisions of JIS B 0601-2001. In addition, for some surface ridge layers, the surface properties of the surface ridge layer are measured in three dimensions using a non-contact type laser microscope, and the convex portion (mountain portion) from the set reference surface (smooth surface) is measured. The maximum height (μm) was measured.
(2) Color tone The color tone was measured according to the JIS Z 8722-2000 standard, and the color tone (H, V, C) of each sample plate was displayed according to the JIS Z 8721-2001 standard.
(3) Glossiness The glossiness was determined as a 45 ° specular glossiness Gs (45 °) in accordance with JIS Z 8741-1997.
(4) Ease of wearing and falling off of marker (4-a) Ease of wearing of marker (marker character recognition)
Look at the line normally written with the test marker (black) at a position 1m away from the board surface and judge whether the line is uneven. In addition, it was determined whether the line was clear when viewed at a position 8 m away, and the evaluation was made in four stages (、 ４, ○, Δ, ×).
(4-b) Ease of marker drop (marker character erasability)
(4) If the line written in (4-a) is left for 24 hours and then erased normally with a urethane foam eraser, see if the board surface is 1 m away from the board surface. Was evaluated and evaluated in four stages (◎, ○, Δ, ×).

About the obtained marker board (product), the projectability was investigated.
(5) Projectivity Place the marker board (product) in a bright place, project an image using a short focus projector toward the marker board (product), and place the projected image at a position 5m away from the marker board. Visually, the image sharpness and the halation suppression degree were evaluated in four stages (４, ○, Δ, ×).

Furthermore, each obtained characteristic was comprehensively evaluated in 10 stages, and it was set as comprehensive evaluation.
The obtained results are shown in Table 3.

  Example of the present invention is an excellent marker boat in which halation is suppressed, the projected image is clear and excellent in projection (reflecting screen function), marker character recognition and marker character erasability are excellent, and the overall evaluation is 8 points or more. It has become. On the other hand, a comparative example (product plate No. 9) in which no titanium oxide-coated particles are blended in glaze, Ra is out of the scope of the present invention, and glossiness Gs (45 °) is out of the scope of the present invention is high. The surface becomes smooth, halation becomes stronger, and the function of the reflective screen is lowered. In addition, a comparative example (product plate No. 10) in which the sulfuric acid method / anatase type non-surface-treated titanium oxide particles are not blended in the glaze glaze, the maximum height of the convex portion is high, and Ra is outside the scope of the present invention is a marker. Character erasability is degraded.

Claims (3)

A marker board having at least one heel layer on a metal substrate,
Out of the above glazing layers, the outermost surface glazing layer is white and has a color tone specified by JIS Z 8721-2001 with a lightness V of more than 8.3 and a chroma C of 0 to 1.0, and JIS B 0601-2001. that the surface roughness Ra: the surface properties is a 0.25～0.8Myuemu, 45-degree specular glossiness defined in JIS Z 8741-1997: Gs (45 ° ) is closed and the surface gloss is 35 to 85, a, And
The surface glaze layer was formed using a glaze glaze in which white titanium gloss glaze was further blended with at least titanium oxide-coated particles and sulfuric acid method / anatase type non-surface-treated titanium oxide particles having a particle size of 0.3 μm or less. A marker board that has a reflective screen function and a marker character recognition and marker character erasability that is characterized by a cocoon layer . After applying the glaze on the surface of the metal substrate and firing to form the lower glaze layer, or without forming the glaze layer, the glaze is applied and fired to form the surface glaze layer. In the marker board manufacturing method,
The glaze glaze is a glaze glaze in which at least titanium oxide-coated particles and sulfuric acid method / anatase type non-surface-treated titanium oxide particles having a particle size of 0.3 μm or less are blended with a white titanium gloss glaze, and the surface glaze layer A method for producing a marker board excellent in reflective screen function, marker character recognizability and marker character erasability, characterized in that the baking temperature is 700 to 850 ° C. The titanium oxide-coated particles are formed into flake-like particles, the titanium oxide-coated particles are blended in an amount of 5 to 15 parts by mass with respect to 100 parts by mass of the white titanium gloss glaze, and the sulfuric acid method / anatase type non-surface-treated titanium oxide particles The method for producing a marker board according to claim 2 , wherein 2 to 8 parts by mass is blended with 100 parts by mass of white titanium gloss glaze.