JPS5953195B2 - blackboard with dark lines - Google Patents

Description

[Detailed description of the invention] The present invention relates to a novel blackboard with dark lines.

As is well known, blackboards with dark lines have vertical lines, horizontal lines, grid lines, dots, and other marks (hereinafter collectively referred to as dark line patterns) that are visible when you approach them but are not noticeable when you move away.
This is a blackboard on which characters and figures can be arranged and written on, and there are three types of blackboards:

The first type has a substrate 12 as shown in FIG.
A dark line pattern 11 is directly formed with an appropriate paint or the like on the surface of a blackboard 10 on which a surface coating layer 13 is formed by applying a blackboard paint.

However, with dark line pattern exposure type products, the dark line pattern is raised in a convex shape, so chalk or blackboard eraser hits the dark line pattern, making writing and erasing difficult. It has drawbacks such as poor durability because it causes abrasion damage in a dark line pattern.

The second type has a substrate 12 as shown in the opening of Figure 2.
An undercoat film layer is formed by applying an undercoat paint or the like on the surface or the surface of the substrate 12.A dark line pattern 11 is formed on the surface with an appropriate paint etc., and a blackboard paint is applied over it to form a surface paint film layer. 13, and the surface coating layer 1 is coated to such an extent that the inner dark line pattern 11 can be seen through.
This is hidden in 3.

Such a dark line pattern concealing type blackboard has a nearly smooth surface, so it is easy to write and erase.However, as the thickness of the surface coating layer 13 increases, the dark line pattern 11 becomes difficult to see. Surface coating layer 1 so that it can be seen through
3 film thickness so-called dark line pattern 11 surface and surface coating layer 1
Since it is necessary to reduce the thickness between the three surfaces, the surface coating layer 13 will be worn away in a short period of time in frequently used areas, exposing the dark line pattern 11, which will only make the appearance worse. It also has the disadvantage of poor writing and erasing properties.

However, in such a concealing type blackboard, the hiding power decreases as the surface coating layer 13 wears, so the dark line pattern 11 gradually takes on a color that contrasts greatly with the surface coating layer 13. , there is a fear that the line may end up exhibiting a color similar to that of a solid line instead of a dark line.

The third type has a substrate 12 as shown in FIG.
A single layer of enamel 14 is provided on the surface, and a dark line pattern 11 is printed on the enamel surface using a silk screen or the like.

This type of blackboard has good durability, writing feel, and erasing ability, but because of its enamel finish, it tends to have uneven hues and color unevenness, making it difficult to obtain products of the same quality. It has problems in terms of production and energy saving, such as poor properties and requires a large amount of thermal energy for high-temperature firing, and therefore has the disadvantage of being extremely expensive.

The present invention has been made to provide a blackboard with dark lines that can eliminate the above-mentioned drawbacks at once, and will be described in detail below with reference to embodiment drawings.

FIG. 1 is a cross-sectional view showing an embodiment of a blackboard with dark lines according to the present invention, together with a partially enlarged view thereof, in which 1 is a substrate, 2 is an ink layer for producing a desired dark line pattern, and 3 is a coating on the surface. Film layer 4 is a dark line pattern.

That is, the blackboard with dark lines of the present invention may be soluble in organic solvents,
In order to develop a desired dark line pattern on a substrate 1, as shown in FIG. At the same time as forming the ink layer 2, a baking-type resin paint, which will be described later, containing an organic solvent capable of dissolving either or both of the above-mentioned colored dye and organic pigment is applied over the entire surface of the substrate and baked to coat the surface. A film layer 3 is formed, and either or both of the above-mentioned colored dye and organic pigment is eluted into the coating film layer 3 to form a desired dark line pattern.

The substrate 1 of the blackboard of the present invention has a thickness of, for example, 0.27 to Q.
A metal plate such as a 5 m/m zinc phosphate coated steel plate or a chemically treated zinc iron plate can be used alone, but if corrosion resistance and adhesion are taken into account, the same metal plate 101 may be coated with a single layer of primer 102 as in the example. It is preferable to use the one provided.

The brimer single layer 102 is made of, for example, an epoxy resin primer coating having a film thickness of about 3 to 10 μm formed by applying an epoxy resin primer paint using a reverse roll coater or the like and baking it at a temperature of 160 to 240° C. for 30 to 120 seconds. A single layer of resin-based primer is preferred.

The ink layer 2 is for expressing a desired dark line pattern, and is coated on the substrate 1 with a dry film thickness of 0.5 to 1.5 using a natural coater or the like using the ink composition described below.
It is a thin film layer formed by applying it in a desired pattern so that it becomes μ, and baking it for 40 to 80 seconds at a temperature of 100 to 200° C. if necessary.

The ink composition used to form this ink layer 2 is composed of a thermosetting resin face (solid content 55 to 65% by weight) as shown in Table 1, a coloring agent, and an organic solvent. Relative to 100% by weight of the solid content of the mold resin face, 5 to 50% by weight of either or both of a coloring dye and an organic pigment that are soluble or partially soluble in an organic solvent, which is a coloring component of the coloring agent. This is a composition that must be blended.

In addition, each of the above-mentioned colored dyes and organic pigments may be used alone or in combination.

The use of a thermosetting resin varnish containing the main components and curing components as shown in Table 1 as a vehicle ensures the desired hardness and abrasion resistance even when an extremely thin ink layer 2 of 0.5 to 1.5 μm is formed. With resin varnishes other than thermosetting resins, the ink layer has poor hardness and abrasion resistance and is easily deformed by heat, making it impossible to obtain a blackboard with good quality dark lines on the side bottom.

In addition, the solid content of the thermosetting resin varnish is 55 to 65% by weight.
This is because within this range, it is possible to form a uniform thin ink layer 2, and the solubility and dispersibility of the colorant are good.

There is no particular restriction on the ratio of the main component to the hardening component of the thermosetting resin varnish, but it is desirable that the ratio by weight of the hardening component is in the range of 5 to 15 to 100 of the main component.

This is because within this range, an ink layer 2 having excellent physical properties such as hardness, abrasion resistance, heat resistance, adhesion, shape retention, and other properties is formed, and also has appropriate heat fluidity.

Among the coloring agents blended into such thermosetting resin varnish, the coloring component is used in the ink layer 2 to the coating layer 3, as described above.
The dark line pattern 4 is developed and formed by being eluted into the varnish, and as mentioned above, this color forming component can be blended in a proportion of 5 to 50% by weight based on 100% by weight of the solid content of the varnish. What is essential is that if it is less than 5% by weight, it will be difficult to form an ink layer 2 with a color density sufficient to hide the substrate 1 due to insufficient blending amount, and the formed dark line pattern 4 will be difficult to distinguish. On the other hand, if the amount exceeds 50% by weight, the amount of the ink composition becomes too large and the dispersibility of the coloring component in the ink composition decreases, resulting in uneven ink layers with unclear outlines. This is because alignment problems such as the formation of dark line patterns 4 with uneven coloring may occur.

On the other hand, the increasing component of the colorant can be applied in a range of 0 to 90% by weight based on 100% by weight of the solid content of the thermosetting resin varnish, but preferably in a proportion of 50 to 90% by weight for the dark line pattern. It is suitable for forming.

In addition, the organic solvent is a diluent for adjusting the viscosity, and the appropriate amount should be determined by considering various factors such as the printing characteristics of the ink composition, cross-wire workability, drying performance, economic efficiency, and safety. All you have to do is decide on the type.

The ink composition used in the present invention is as described above, but the viscosity of this ink composition may be adjusted with an organic solvent during application so that the measurement time using a Zahnkup #7 viscometer is in the range of 9 to 11 seconds. desirable.

If it deviates from this range, pigments may settle or
This is because various misalignments may occur, such as unsatisfactory coating, uneven coloring of the ink layer, and deterioration of the surface smoothness of the ink layer.

The coating layer 3 on the surface of the blackboard with dark lines of the present invention is coated with a baking-type resin paint containing an organic solvent capable of dissolving the coloring component in the ink composition, and coated with a roll coater or the like to a dry film thickness of 15 to 15 mm. It was coated to a thickness of 25μ and dried for 20 to 2,400 seconds at a temperature of 80 to 300°C. Immediately after this coating and while the baking was drying, the coloring component was removed from the ink layer 2. That is, the dark line pattern 4 is developed and formed in the coating layer 3 by dissolving the colored dye and/or organic pigment into the coating layer 3 into a dispersed state as shown in FIG. 1, for example.

The baking-type resin paint used here may be one that has been conventionally used as a paint for blackboards, but the following ones are preferable.

For example, with a baking type synthetic resin solution where the solvent is an organic solvent, 40 to 12
A plate-like or acicular pigment that is blended at 0% by weight and kneaded and dispersed to have a pigment particle size of 10 to 30μ, and a pigment that is blended at 5 to 100% by weight based on 100% by weight of the resin solid content and has an average particle size of 10 to 30μ. It consists of an anti-wear agent with a new Mohs hardness of 11 or more mixed and dispersed so that the particle size is larger than the above pigment particle size and about 45 μm or less, and a colored and matte pigment to obtain the desired color.

A blackboard using the above paint has good fluidity and excellent dispersion stability of pigments and anti-wear agents, the paint film does not crack even when rapidly cooled after baking and drying, and has a pencil hardness of 6μ or more. Moreover, it has good flexibility, and even if it wears down after long-term use, the anti-wear agent maintains a suitable surface roughness, so the writing quality, legibility, etc. are not impaired.

In addition, if the above-mentioned wear-resistant agent is 20% by weight or more in this baking-type resin paint and the new Mohs hardness is 12 or more, a blackboard having a pencil hardness of 9μ or more can be obtained.

Next, the blackboard with dark lines of the present invention will be described in more detail with reference to Examples.

(Example 1) Long coil-wound steel plate treated with zinc phosphate film (thickness:
0.27 mm) was continuously fed while unwinding, and an epoxy resin primer paint was applied to the surface using a reverse roll coater so that the dry film thickness was 5μ.
℃ for 45 seconds to form a single layer of primer to form a substrate. On this substrate, the ink composition shown in Table 2 below (adjusted to Zahn Cup #7 viscosity: 10 seconds) was applied with grid lines on the surface. Apply to a dry film thickness of 1μ using a patterned natural coater, and apply the following second coat on top.
The dark green baked-on resin paint on the surface was applied with a roll coater to a dry film thickness of 20 μm.
It was baked and dried at 50° C. for 80 seconds to obtain a blackboard with dark lines.

The coloring components in the ink layer of this blackboard dissolve into the coating layer on the surface, resulting in a dark red grid-like dark line pattern that is visible when you approach it, but becomes unnoticeable when you move away, with clear outlines and uniform color. had been formed.

(Example 2) Example 2 except that a 0.27 mm thick chemically treated galvanized iron plate was used instead of the zinc phosphate film-treated steel plate, and the ink composition and baking-type resin paint shown in Table 3 below were used. A blackboard with dark lines on which a dark blue dark line pattern was formed was manufactured in the same manner as in Example 1.

Table 4 shows the results of characteristic tests conducted on the blackboards obtained in Examples 1 and 2 above.

In the table above, the non-dark line area refers to the part of the blackboard with dark lines excluding the area with the dark line, and the dark line area refers to the area with the dark line.

However, regarding the abrasion resistance and processability of test item 4.5, the non-dark line area refers to a blackboard with the same composition as the present invention except for the ink composition of the present invention, and the dark line area refers to the blackboard with the dark line of the present invention. shows.

The test items for each performance are as follows.

1. Pencil hardness Evaluation method according to JISK54006.14 2. Ease of writing: Smoothness of the stroke and sharpness of the letters when written with chalk 3. Ease of erasing: When the letters are wiped off with a blackboard eraser ( Degree of ease of erasing (1 time) 4, wear resistance taper wear tester, wear wheel C8-17, 1kg
Degree of weight loss when rotated 1000 times under load: 5, workability: The bent part after the test piece was sandwiched between 5 plates of the same thickness as the test piece, folded 180 degrees 9, and tightened in a vise according to JIS G3312. As can be understood from the above explanation, in the blackboard with dark lines of the present invention, the colored dye and/or organic pigment contained in the ink layer 2 is applied to the surface having a desired thickness. By dissolving it into the coating layer 3 and coloring the coating layer 3 itself in a dispersed state, the desired dark line pattern 4 is developed and formed.
Of course, the surface is smooth and has good writing and erasing properties, but the dark line pattern 4 will not disappear until the coating layer 3 is almost completely worn out, which will greatly improve the service life. It will be a long one.

Moreover, since the dark line pattern is formed on the coating layer itself, it is difficult to prevent wear of the surface coating layer 13, unlike the conventional one that utilizes the hiding power of the surface coating layer 13 as shown in Figure 2. The brightness and color tone of the dark line pattern will not change as the hiding power decreases, the dark line pattern will not be exposed to the extent that it becomes noticeable, and the exposed dark line pattern will not be damaged, so it is in good condition and is almost as good as new. The format, writing style, and erasing style can be maintained.

In addition, when the ink layer 2 for expressing a dark line pattern is formed using an ink composition whose vehicle is a thermosetting resin varnish, as in the blackboard of the present invention, the ink layer 2 is extremely thin. There are no defects or thermal deformation, and the result is a uniform coating with a hard, smooth surface, so the dark line pattern that appears does not have defects, deformation, uneven color, etc., or bleed. Moreover, when the ink layer 2 is such an extremely thin and uniform layer, the surface coating layer 3 is free from unevenness, resulting in a high-quality blackboard.

Furthermore, by variously changing the types, combinations, and amounts of coloring components, ink compositions of various hues can be obtained, and by arbitrarily selecting these, dark line patterns 4 of various hues can be created in the coating layer 3 on the surface. can be formed.

In particular, if the hues of the surface coating layer 3 and the dark line pattern 4 are selected to be similar, a blackboard with dark lines of good quality that does not disturb the viewer can be obtained.

Furthermore, from the viewpoint of manufacturing and energy saving, the blackboard of the present invention can be manufactured in a uniform manner easily and continuously by just going through two steps, the ink layer forming step and the surface coating layer forming step, which do not require very strict process control. It can be produced in large quantities, and when it is manufactured on a continuous line, baking of the ink layer can be simplified or omitted, so it requires less thermal energy.
Compared to the conventional enamel blackboard described above, there are advantages such as the ability to manufacture a blackboard with dark lines with excellent performance easily and inexpensively.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of a blackboard with dark lines according to the present invention together with a partially enlarged view thereof, and FIG. 2A and C are cross-sectional views of a conventional example. (Main symbols in the drawing) 1... Board, 101.
...Metal plate, 102... Primer layer,
2... Ink layer, 3... Paint film layer, 4...
...Dark line pattern.

Claims (1)

[Claims] 1. An ink composition prepared by blending either or both of a coloring dye and an organic pigment that are soluble or partially soluble in an organic solvent at a ratio of 5 to 50% by weight based on 100% by weight of the solid content of a thermosetting resin varnish. In addition to forming an ink layer to develop a desired dark line pattern on a substrate, the printing process contains an organic solvent capable of dissolving either or both of the above-mentioned coloring dye and organic pigment over the entire surface of the substrate. A blackboard with dark lines formed by applying a molded resin paint to form a coating layer, and eluting either or both of the above-mentioned colored dye and organic pigment into the coating layer to form a desired dark line pattern.