JPH02153080A - Enameled board also acting as marker screen and production thereof - Google Patents

Abstract

PURPOSE:To ensure erasability for a marker and to attain nonhalation by glazing a board substrate having ground coat enamel with slip prepd. by blending Ti-contg. white overglaze having a specified compsn. with Ti-contg. mat glaze having a specified compsn. in a prescribed ratio and by baking the glazed substrate. CONSTITUTION:A board substrate having ground coat enamel formed by glazing and baking is glazed with slip prepd. by blending Ti-contg. white overglaze (A) with Ti-contg. mat glaze (B) in 6/4-4/6 ratio of A/B and the glazed substrate is baked. The glaze A consists of 35-60 parts SiO2, <=3 parts Al2O3, 15-20 parts B2O3, 16-22 parts TiO2 and 16-22 parts Na2O+K2O. The glaze B consists of 25-35 parts SiO2, 16-25 parts Al2O3, 4-12 parts B2O3, 16-22 parts TiO2 and 18-24 parts Na2O+K2O. The title board ensuring erasability for a marker and having satisfactory brightness and reflective luminance is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is a proposal for a board that serves both as a marker board and a screen used for an overhead projector, a slide, etc., and a method for manufacturing the same.

[Conventional technology]

The surface material for markerboards should be (1) easy to write on with a marker, and (2) easy to erase (erasability).
, <31 Easy to see, (4) Excellent stain resistance, (5) Excellent durability (wear resistance), (6) Excellent weather resistance (chemical resistance), (7) Characteristics such as good design are required. Materials used for marker boards that meet these demands include enamel, painted S-board, and plastic.

Among these materials, enamel marker boards have recently been in the spotlight, and the demand for them is increasing year by year. In the case of this enamel marker board, among the above characteristics (
1) and (2) are important and are the key to commercialization. In particular, erasability is related to the smoothness of the board surface, and the smoothness of the board surface is closely related to the specular gloss of the board surface, and it is known that the smoother the surface, the higher the glossiness. There is.

Generally, in the case of such enamel markerboards, the gloss level of the board surface is GS (4
5°) was required to be 60% or more.

On the other hand, overhead projectors and slide screens require (1) visibility from a wide range of locations, (2) accurate color reproduction, and (3) brightness (
It is required to have characteristics such as being easy to see, (4) having a smooth plate surface, (5) having excellent durability, and (6) being functional.

The above (4) to (6) are similar to the characteristics required of the marker board, but (1) to (3) are different characteristics. That is, if the light emitted from an overhead projector or slide projector is reflected in a certain direction, the image will not be visible at that location, so it is desirable that the board surface diffusely reflect the light. This is characteristic (1). However, in order to diffuse and reflect light, it can be said that, contrary to the marker board, it is preferable that the specular gloss is low. In addition, the characteristics of (21, (31) differ depending on the brightness of the light source, but the higher the glossiness of the board surface, the better. In order to make it easier to see, the reflective brightness of the board surface is high, and the reflection at any angle is It is important that the brightness remains unchanged.

As a screen board that can meet these demands,
Conventionally, silver paint with metallic luster (high gloss) is treated with irregularities on its surface to make it semi-glossy, resulting in abnormally high brightness (dazzling appearance) in the 0° direction. A method has been proposed to prevent this.

However, when the surface is textured, the ease of writing and erasing with a marker etc. is impaired, resulting in the defect that the board cannot be used as a marker board.

As explained above, the characteristics required for marker boards and screen boards are generally contradictory, and for this reason, it has conventionally been difficult to manufacture the above-mentioned dual-purpose boards.

However, when using an overhead projector or slide, it is necessary to prepare the screen and clean up after each use, and on the other hand, there is also a desire to write on the screen while explaining the use. In such cases, a board (marker and screen board) that has both functions has been desired.

In view of these circumstances, conventional methods for controlling the glossiness of the enamel surface include (1) enamel blackboard (GS75°
Method of applying matte glaze to obtain (<15%), (
2) A method of glazing a frit with an increased amount of silica or clay as a mill additive is known. Although these conventional techniques can reliably reduce the glossiness of the enamel surface, undissolved substances appear on the surface, hindering the ease of writing and erasing the marker, and on the other hand, the total reflectance is low. However, when used on a screen board, there was a drawback that the image became dark.

Furthermore, other known methods for controlling glossiness include JP-A-63-230537 and JP-A-63-2305.
Examples include those disclosed in Publication No. 38.

[Problem to be solved by the invention]

In these known methods, the composition of the glaze is 5 int/Ti.
0z is in the range of 65/35 to 40/60, and in order to ensure smoothness after firing, Lid, P, 0.
Ya ZrO.

It is characterized by the addition of However, the gloss level GS (75') after firing is less than 50% (#G545°:
25%), which resulted in a low total reflectance, resulting in a dark image when used as a screen board, and the use of Lid and Zr0z, which resulted in a high glaze.

Therefore, the present invention was devised for the purpose of developing a board that can overcome the contradictory characteristics mentioned above at the same time. We propose a technology for forming an enamel surface that has excellent marker erasability and is no different from conventional materials.

[Means to solve the problem]

As a result of diligent efforts to achieve the above-mentioned object, the present inventors have come up with a manufacturing method and a board with an enamel surface formed by the method, which has the following features. Namely, (1) Undercoating On a glazed board substrate, a Ti white glaze (A) with the following component composition and a Tt matte glaze (B) are placed in a ratio such that the A/B ratio is within the range of 674 to 4/6. A blended slip or a slip to which the following mill additive (C) is added in an amount of 20% or less in the outer frame amount,
The gloss level of the enamel surface is GS (45
A:SiO□:35 An enamel marker/screen board, characterized by its excellent marker erasability and excellent screen function by setting the angle (°) in the range of 30 to 60%. ~60 copies, AI
! 01: 3 parts or less, Btus: t5-20 parts, TiO□: 16-22 parts, Na2O+K2O:
16-22 parts B: SiO□: 25-35 parts, AIto! : 16~
25 parts, Bt03: 4-12 parts, TtOz: 16
~22 parts, NagO+K2O: 18-24 parts C:StO□: 5 parts, T)Ot: 25-35 parts,
5b2O+: 30-40 parts, CaO: 20-30
Suggest a section.

In addition, the present invention provides a method for manufacturing the above-mentioned board, as follows: (2) During milling, a Ti overglaze (A) having the following component composition and a Ti matte glaze (B) are mixed with an A/B ratio of 674.
A slip blended in a ratio within the range of ~4/6 or a slip with the following mill additive (C) added in an amount of 20% or less in the outer frame amount was prepared, and this slip was glazed and fired with a subglaze. A method for manufacturing a board that serves as both a marker and a screen, characterized by applying a glaze onto a board and then firing it, A: SiO□: 35 to 60 parts, A1□03: 3
Parts or less, BzCh: 15 to 20 parts, TiO□: 1
6 to 22 parts, Na2O+K2O: 16 to 22 parts B:SiO□: 25 to 35 parts, A1□o, : 16 to
25 parts, B, 0. : 4 to 12 parts, TiO□ : 16
~22 parts, Na, 20 to 0+: 18-24 parts C: SiO□: 5 parts, TiO□: 25-35 parts, 5b
z03: 30-40 parts, Cab: 20-30 parts are suggested.

[For production]

In the present invention, the reason why a board that can be used both as a marker board and a projection screen is obtained is that the glazed enamel surface of the board has the smoothness required for a marker board,
This is because the component composition and glossiness of the frit are adjusted as described above so that the brightness and reflected luminance distribution required for a projection screen are balanced.

In other words, Ti
By using the top white Ti matte color as a mixed frit in the present invention, the Ti top white color acts to fill in the unevenness and cracks that are seen when only the matte shaft is used, thereby reducing the The gloss level also depends on the formation of a smooth surface.

Therefore, in the present invention, the reason why such a mixed frit consisting of Ti top white and Tt matte glaze is effective will be explained below.

Table 2 shows the gloss level GS (45
This is the result of measuring .°). As can be seen from this Table 2,
Depending on the formulation, the gloss may be too high or too low, and "roughness" or "bubble defects" may occur on the enamel surface.

For example, many of the magnetic 3 frits with a high SiO□ content of 53 parts in the Ti overglaze have rough enamel surfaces and many bubble defects. In particular, Ti matte color SiO
Foam defects are noticeable in the formulation examples of 11h9 and 1.0, which have a low □. On the other hand, in the case of a frit layer 5 with a low Ti top white 5in2, bubble defects occur most often.

In this regard, even if the frits N11, 2, and 4 have a Ti top white composition that is within the scope of the present invention, the frit No. It can be seen that in the frit Na1O, which has a high At, O, and has a high At, O, roughness is observed on the enamel surface, and the erasability as a marker board is inhibited.

From the above results, in order to stabilize the surface quality, T
i Upper white component composition: SiO□: 35 to 50 parts, A1□0.20 to 3 parts, B20. : 15-20 parts, Ti0g: 16''22 parts, Na2O+K2O:
It is necessary to keep the amount in the range of 16 to 22 parts, and
The Ti matte color component composition is Sing: 25
~35 parts, Altos: 16-25 parts, B, 0.
: 4-12 parts, Ti (h: 16-22 parts, Na2
O+K2O: Must be in the range of 18 to 24 parts.

Table 1 (parts) *Glossiness GS (45''') In the present invention, mill additives are further used in the above frit composition. Among these mill additives, TiO□ and CaO reduce the surface gloss. sb and o have the effect of smoothing the surface.

That is, if TiO□ or CaO is out of the appropriate range (too much or too low), unevenness will occur due to undissolved matter. On the other hand, SbgOi is blended in a balanced manner with the TiO□ and CaO. therefore,
In the present invention, the composition of the mill additive (C) is SiO
□: 5 parts, TiO□: 25-35 parts, 5b2Os:
Suitable ranges are 30 to 40 parts and CaO: 25 to 30 parts.

It should be noted that it is preferable to add this additive at the time of milling; if it is added after milling, sufficient mixing will not be possible.
Therefore, remixing is required, which increases the number of stirring steps and increases costs.

Next, in the present invention, the reason for specifying the characteristics required for the screen function, that is, the reflected brightness, will be explained based on FIG. 1 in comparison with examples of various boards.

This reflected brightness measurement is performed using the cabin AF − as the light source.
250, projected from the 0° direction (2 m), and reflected luminance measured from -75° to +75° (luminance meter LS-100 manufactured by Minolta) at the same position <2 m away.

As is clear from Figure 1, (a) Specular gloss GS (60
In the case of a chalk blackboard with a low luminance of 5%, the variation in brightness was small, but the reflected brightness was also low, making the screen quite dark when slides were projected.

([+) In the case of an enamel marker board with a high specular gloss GS (60°) of 94%, the brightness was quite high in the 0° direction (9500 cd/rn"), causing halation and looking dazzling. ( c) In the case of the !4go board, which is said to exhibit total internal reflection, its brightness is high and its distribution is smooth, so it seems to be suitable for slides.
d) Silver with a textured surface that is used exclusively for screens has a slightly high brightness distribution near 0° (285
cd/m”) was observed.

In comparison, (n) the dual-purpose board of the present invention with gloss level GS (60″#42%) has a brightness slightly higher than silver (370 cd/m″), but its distribution state is silver. It shows almost the same tendency as the wood, and it can be seen that it can be used satisfactorily as a screen board. Therefore, the gloss level of the enamel surface is GS
GS containing 42% at (60°) (45°) 30~6
0% is valid.

The reason why the glossiness GS (45°) of 30 to 60% is effective and its effects will be explained below based on Examples.

〔Example〕

Example-1 A Ti upper white glaze (A) and a Ti matte glaze (B) having the compositions shown in Table 3 were placed on a board substrate on which a lower glaze was applied and fired at a blending ratio of 1010 to 0/10. A mixed frit was prepared by mixing the frit, milled to form a slip, and the slip was glazed and fired. As a comparative material, a slip glaze with 5.10% of silica stone added as a mill additive was used to reduce gloss. After firing the enamel, specular gloss, marker erasability, degree of halation during slide projection, and surface condition were observed.

Specular gloss was measured using a variable angle gloss meter (VGS) manufactured by Nippon Heavy Industries.
-ID) and measured at GS (45°). The erasability of the marker is determined by using a commercially available marker, leaving it for 24 hours after drawing on the enamel surface, and then writing it on a commercially available eraser for 60 minutes.
A weight of 0 g is placed on the marker and the marker remains after one round trip. Visually judge the degree of remaining marker. Markers that have completely disappeared are marked (○), marks that remain faintly (△), and marks that remain considerably (x). ). In addition, halation during slide projection can be reduced using Cabin Industrial's slide projector (AF-
250) and when viewed from the front, the light source of the slide is not visible and the image is clear (○)
If the light source is slightly visible and the image is slightly blurred, it is (Δ), and if the light source is clearly visible and the image is dazzling and blurred, it is (×
). The results are shown in Table 4.

If the specular gloss is 60% or more (A/B > 7/3), the board surface will suffer from scratches, and if it is 20% or less (A/B <
3/7), the surface became rough and the erasability of the marker deteriorated. In addition, in sample IVh3 to which a large amount of silica stone was added as a mill additive, the gloss level decreased, but unevenness due to undissolved matter appeared on the surface, and erasability deteriorated.

Samples 1lh7 to 1lh9 to which silica stone was not added had lower glossiness, but because the surface was smooth, marker erasability was good, and good boards were obtained without halation during slide projection. That is, for a marker board and a screen board, it is effective to set the blending ratio of Ti overglaze/Ti matte glaze in the range of 674 to 4/6.

Note that even if pigments are added to a transparent glaze, Ti matte glaze does not cause halation and provides a plate surface with good marker erasability, but when considering color reproduction, etc., Ti-based matte glaze is better. preferable.

Table 3 (Part) Example 2 In the same manner as in Example 1, the blending ratio of the glaze shown in Table 1 was changed to 1010 to 2/8 as in Sample I*l14 to 28.
Change to 5i(h (5 parts) Ti1t (30 parts)
A slip to which an additive (C) consisting of -Sb, 03 (35 parts) and -Cab (30 parts) was added in a range of 10 to 30% per inch of the outer frame was glazed and fired.

After baking, specular gloss, marker erasability, degree of halation during slide projection, and surface texture were observed using the methods described above. The results are shown in Table 5.

By adding the additive (C), the specular gloss level decreased and halation was eliminated, but when the amount added exceeded 30%, the surface became slightly rough and the erasability of the marker decreased slightly. Furthermore, looking at the blending ratio of the glaze, it was found that as a result of the expected reduction in gloss due to mill additives, a plate surface with no halation and good marker erasability could be obtained even with just a white Ti glaze. However, when the amount added was small, the gloss was high and halation was noticeable (Sample 1
3).

Furthermore, when the content of the matte glaze exceeded 60 parts, the erasability of the marker deteriorated.

From the above results, in order to obtain a dual-purpose board with good marker erasability and no halation during slide projection,
The mixing ratio of Ti white glaze (A) and Ti matte glaze (B) is to
Blended in the range of 10 to 6/4, and the additive (C) is 20
% or less.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to simultaneously achieve so-called erasability and non-halation, which have good smoothness required for a marker board and good brightness and reflective luminance required for a projection screen. . Therefore, it is possible to effectively manufacture a board that can serve both as a marker board and a projection screen.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the distribution of reflected luminance of various boards. Patent applicant Kawatetsu Metal Industry Co., Ltd. Agent Patent attorney Jun Ogawa Sando Patent attorney Morio Nakamura

Claims (4)

[Claims] (1) On a board with underglaze, T with the following composition
Glaze and fire using a slip containing i-white glaze (A) and Ti matte glaze (B) in a ratio such that the A/B ratio is within the range of 6/4 to 4/6, Glossiness G of the enamel surface
By setting S (45°) in the range of 30 to 60%,
An enamel marker/screen board that is characterized by its excellent marker erasability and at the same time has an excellent screen function. A: SiO_2: 35 to 60 parts, Al_2O_3: 3 parts or less, B_2O_3: 15 to 20 parts, TiO_2: 16
~22 parts, Na_2O + K_2O: 16-22 parts B: SiO_2: 25-35 parts, Al_2O_3: 16
~25 parts, B_2O_3:4-12 parts, TiO_2:1
6 to 22 parts, Na_2O+K_2O: 18 to 24 parts (2) On the board substrate with underglaze, T with the following composition
Blending the i-top white glaze (A) and the Ti matte glaze (B) in a ratio such that the A/B ratio is within the range of 6/4 to 4/6,
And by glazing and firing using a slip to which 20% or less of the following mill additive (C) has been added in terms of outer frame amount, the gloss level GS (45°) of the enamel surface is in the range of 30 to 60%. An enamel marker and screen board that is characterized by its excellent erasability and at the same time has an excellent screen function. A: SiO_2: 35 to 60 parts, Al_2O_3: 3 parts or less, B_2O_3: 15 to 20 parts, TiO_2: 16
~22 parts, Na_2O + K_2O: 16-22 parts B: SiO_2: 25-35 parts, Al_2O_3: 16
~25 parts, B_2O_3:4-12 parts, TiO_2:1
6 to 22 parts, Na_2O + K_2O: 18 to 24 parts C: SiO_2: 5 parts, TiO_2: 25 to 35 parts, S
b_2O_3: 30-40 parts, CaO: 20-30 parts (3) When milling, Ti overglaze (A
) and Ti matte glaze (B) with an A/B ratio of 6/4 to 4.
A method for manufacturing a board that can be used as a marker and a screen, which comprises adjusting a slip blended in a ratio within the range of /6, applying this slip onto a board substrate that has been glazed and fired with an underglaze, and then firing it. . A: SiO_2: 35 to 60 parts, Al_2O_3: 3 parts or less, B_2O_3: 15 to 20 parts, TiO_2: 16
~22 parts, Na_2O + K_2O: 16-22 parts B: SiO_2: 25-35 parts, Al_2O_3: 16
~25 parts, B_2O_3:4-12 parts, TiO_2:1
6 to 22 parts, Na_2O+K_2O: 18 to 24 parts (4) When milling, use the following Ti white glaze (A) and the Ti
A slip in which the matte glaze (B) is mixed in a ratio such that the A/B ratio is within the range of 10/0 to 6/4, and at the same time, 20% or less of the mill additive (C) is added in the outer frame amount. A method for manufacturing a board made of enamel that can be used as a marker and screen, which comprises adjusting the slip, applying a glaze on a board substrate which has been glazed and fired, and then firing the slip. A: SiO_2: 35 to 60 parts, Al_2O_3: 3 parts or less, B_2O_3: 15 to 20 parts, TiO_2: 16
~22 parts, Na_2O + K_2O: 16-22 parts B: SiO_2: 25-35 parts, Al_2O_3: 16
~25 parts, B_2O_3:4-12 parts, TiO_2:1
6 to 22 parts, Na_2O + K_2O: 18 to 24 parts C: SiO_2: 5 parts, TiO_2: 25 to 35 parts, S
b_2O_3: 30-40 parts, CaO: 20-30 parts