JPS6228985B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a paint for blackboards, and the paint component includes a particle size of 80%.
A mixture of one or more types of glass powder selected from glass beads with a particle diameter of 80μ or less, glass flakes with a thickness of 1 to 7μ and a particle size of 50μ or less, and glass fibers with a diameter of 20μ or less and a length of 100μ or less. This invention relates to a blackboard paint characterized by being made of a dispersed material. When a blackboard is used, the blackboard is required to have characteristics such as ease of writing and erasing characters, as well as resistance to leaving behind chalk powder and resistance to scratching of blackboard paint caused by chalk. Various studies have been made regarding the materials used in paints, the particle size of particles dispersed during the manufacture of blackboard paints, and the like. In addition, there is a problem with Chiyoke that dust gets on clothes and hands when used, so dustless Chiyoke, which does not easily generate Chiyoke powder, has recently been used. This dustless stiff yoke is made by extruding calcium carbonate powder mixed with a coagulant, or made by coating plaster gypsum with a special resin. When this happened, there was a problem in that the ingredients in the chalk adhered to the surface of the blackboard and the traces of the letters were difficult to erase even after the letters were erased, making the blackboard very difficult to read. In addition, such dustless scratches tend to damage the surface of blackboards, and blackboard paints are required to have abrasion resistance against repeated writing and erasing. Japanese Patent Publication No. 51-18251 states that blackboard paint is continuously applied with a roll coater and baked to form a blackboard. There are problems with leaving marks and wear resistance. In addition, in Japanese Patent Publication No. 55-33997, as a means to solve the above problem, it is described that silicon carbide or hard alumina with a Mohs hardness of 11 or higher is added to the blackboard paint to improve the wear resistance of the blackboard paint. However, there was a drawback that there were traces of letters left behind. The present invention has been made in view of the above points, and it is an object of the present invention to provide a paint for a blackboard that does not leave any traces of the dustless scratchy yoke even when the dustless scratchy yoke is used and has excellent abrasion resistance. The purpose is to This will be explained in detail below. The main component resin for coating film formation is formed by adding a crosslinking agent to a thermosetting resin such as an acrylic resin including a self-crosslinking type, a saturated polyester resin including an alkyd, an epoxy resin, and a urethane resin. As the crosslinking agent, amino resins such as melamine resins and urea resins, block type isocyanates, etc. can be used, and it is preferable to use acrylic resins or saturated polyester resins containing alkyd with block type isocyanates as the crosslinking agent. It is the best in terms of stain resistance and wear resistance of the yoke. The amount added is based on the solid content of the thermosetting resin.
It is preferable to mix 20 to 100 parts by weight of crosslinking agent solids per 100 parts by weight. Extender pigments are made of calcium carbonate, titanium oxide, magnesium oxide, aluminum oxide, silicate powder, barium sulfate, clay, talc, etc.If the particle size is less than 10μ, it will be easier to write dustless paint, and if the particle size is 30μ or more, it will be easier to write. Since there is a problem with ease of erasing, it is preferable to use extender pigments with a particle size of 10 to 30 microns. Glass powder particle size
It is made of glass beads with a particle size of 80μ or less, glass powder with a particle size of 80μ or less, glass flakes with a thickness of 1 to 7μ and a particle size of 50μ or less, glass fibers with a diameter of 20μ or less and a length of 100μ or less, especially with a particle size of 40μ. Preferably, the following glass beads are used: If the glass powder used includes glass beads or glass powder with a particle size of over 80μ, glass flakes with a thickness of over 7μ and a particle size of over 50μ, and glass fibers with a diameter of over 20μ and a length of over 100μ, the glass powder is included. The surface smoothness of the blackboard paint film deteriorates. The extender pigment is mixed in an amount of 50 to 200 parts by weight based on 100 parts by weight of the resin solid content of the main component resin for coating film formation, and is preferably dispersed to have a particle size of 30 to 60 microns using a grind gauge. Further, the glass powder is blended in an amount of 15 to 100 parts by weight, preferably 20 to 50 parts by weight, per 100 parts by weight of the solid content of the above-mentioned mixture of the main component resin for coating film formation and the extender pigment, and is mixed with a powder of 40 to 70μ by a grind gauge. It is preferable to disperse it so that If the amount of glass powder is less than 15 parts by weight, the effect of adding glass powder will be small, and if it exceeds 100 parts by weight, the appearance of the surface of the blackboard manufactured with the blackboard paint will be poor and the dust stain will be difficult to remove. There are traces of chiyok. In addition, solvents, coloring pigments, and the like are added as appropriate to prepare blackboard paints. The blackboard paint is produced in the following manner. First, the extender pigment is mixed with the main component resin for coating film formation, and dispersed using a dispersing machine such as a roll mill, sand grind mill, or ball mill to obtain a particle size of 30 to 60 μm as measured by a grind gauge. The particle size of the extender pigment at this time affects the ease with which letters can be written on and erased from the dust-resti-yoke with respect to blackboard paint. Next, add and mix glass powder to the above mixture and use a disperser to obtain a particle size of 40 to 70μ.
The blackboard paint is produced by dispersing the mixture so that it becomes viscous, and then adding a solvent to adjust the viscosity.
A blackboard is prepared using the blackboard paint thus obtained in the following manner. First, pre-painting treatment is performed according to the method normally applied to the surface of materials such as metal plates, and then an undercoat mainly composed of epoxy resin or saturated polyester resin is baked using a natural or reverse roll coater or flow coater. Apply. The baking conditions for the undercoat are preferably such that the maximum temperature of the material is around 200°C for about 60 seconds, and the coating is preferably applied so that the film thickness after drying is 5 to 10 microns. Next, the blackboard paint is baked using a reverse roll coater or a flow coater so that the dry film thickness is 20 to 30μ. It is preferable to bake the material for about 75 seconds at a maximum temperature of around 230°C, and in the case of roll coater painting, the viscosity of the blackboard paint should be 90 to 120 seconds with a No. 4 food cup, and for flow coater painting. In such cases, it is preferable to set the time to 30 to 60 seconds. Note that when the blackboard paint is applied once, the undercoat can be omitted. In this way, a blackboard can be created in a short time. When a blackboard paint in which glass powder is dispersed is applied to a material and cured, a coating film in which the glass powder is evenly dispersed is obtained, making it possible to create a blackboard with excellent wear resistance. In addition, the surface of the glass is smooth, making it easy to remove adhering dust particles and coagulating agents or coating agents in the dust-free glass. Especially when glass beads are used, the surface of the beads is spherical, so the surface is smooth and dust-free. It is possible to obtain a blackboard paint that has good resistance to leaving traces on restyoke and good abrasion resistance. As described above, in the present invention, glass powder is mixed and dispersed in the paint component, so when the blackboard paint is applied and cured, a coating film with glass powder uniformly dispersed on the surface can be obtained, and It is possible to obtain blackboard paint with excellent wear resistance,
Also, one or more types of glass selected from glass beads with a particle size of 80μ or less, glass powder with a particle size of 80μ or less, glass flakes with a thickness of 1 to 7μ and a particle size of 50μ or less, and glass fibers with a diameter of 20μ or less and a length of 100μ or less. Since powder is used, it is possible to give the surface of the coating film formed from this blackboard paint the smoothness of glass powder, and it is also possible to remove dust adhering to the surface, as well as agglomerating agents or coating agents in dustless paint. This makes it possible to easily carry out the process and eliminate any traces left by the dust rest yoke. The present invention will be specifically explained below based on Examples. <Example 1> Titanium oxide 2.9 parts by weight Phthalocyanine blue 1.8 〃 Yellow lead 2.6 〃 Fine powder clay 9.5 〃 Precipitated barium sulfate 9.5 〃 Fine powder silica 2.2 〃 Acrylic resin varnish (solid content 50%) ¹
33.0 Block isocyanate varnish (60% solids)
² 14.0 〃 Isophorone 4.1 〃 Solbetsuso 150 4.1 〃 Glass beads (particle size 40μ or less) 16.3 〃 Total 100.0 〃 Among the above formulations, titanium oxide, phthalocyanine blue, yellow lead, fine powder clay, precipitated barium sulfate, fine powder silica , acrylic resin varnish, and isophorone were mixed and dispersed using a disperser so that the pigment particle size was 40μ, and then blocked isocyanate varnish was mixed. Add glass beads (particle size 40) to this mixture.
μ) with a high-speed stirrer and a grind gauge with a particle size of 50.
A blackboard paint was obtained by dispersing the mixture in μ and adjusting the viscosity by adding Solbetsuso 150. Next, granodine 46
(Zinc phosphate treatment agent manufactured by Nippon Paint Co., Ltd.)
On a galvanized steel plate (thickness: 0.3 mm) that had been pre-painted by Co., Ltd., an epoxy resin primer for pre-recording was applied using a natural roll coater to a dry film thickness of 5 μm, and the material was coated at the maximum temperature reached at 200°C. 60
Baked for seconds. Next, a blackboard paint was applied using a reverse roll coater so that the dry film thickness was 25 to 28 μm, and the material was baked at the maximum temperature of 230° C. for 75 seconds to obtain a blackboard. In addition, when painting with a roll coater, the viscosity is No.
90 to 120 seconds is appropriate for 4 fed cups. <Example 2> Titanium oxide 2.1 parts by weight Phthalocyanine blue 1.3 〃 Yellow lead 1.8 〃 Fine powder clay 8.7 〃 Fine powder calcium carbonate 4.6 〃 Fine powder silica 2.3 〃 Acrylic resin varnish (solid content 58%) ³
37.0 〃 Melamine resin varnish (solid content 60%) ⁴
11.9 〃 Isophorone 5.6 〃 Solbetsuso 150 5.6 〃 Glass beads (particle size 40μ or less) 19.1 〃 Total 100.0 〃 After mixing and dispersing the pigment and acrylic resin varnish in the same manner as in Example 1 with the above composition, mix the melamine resin varnish. Then, glass beads were dispersed in this to obtain a blackboard paint. A blackboard was prepared by painting with this blackboard paint in the same manner as in Example 1. <Example 3> Titanium oxide 2.6 parts by weight Phthalocyanine blue 1.7 〃 Yellow lead 2.3 〃 Fine powder clay 16.8 〃 Fine powder silica 2.3 〃 Acrylic resin varnish (solid content 50%) ⁵⁾
38.2 Block isocyanate varnish (55% solids)
⁶⁾ 17.3 〃 Isophorone 2.6 〃 Solbetsuso 150 2.6 〃 Glass beads (particle size 40μ or less) 13.6 〃 Total 100.0 〃 After mixing and dispersing the pigment and acrylic resin varnish in the same manner as in Example 1, block isocyanate varnish was mixed. A blackboard paint was obtained by dispersing glass beads in this. Using this blackboard paint, painting was performed in the same manner as in Example 1 to create a blackboard. <Example 4> Titanium oxide 2.8 parts by weight Phthalocyanine blue 1.8 〃 Yellow lead 2.5 〃 Fine powder clay 9.3 〃 Precipitated barium sulfate 9.3 〃 Fine powder silica 2.2 〃 Acrylic resin varnish ¹ ) 32.3 〃 (Solid content 50%) Blocked isocyanate varnish ² ) 13.7 〃 (solid content 60%) Isophorone 6.0 〃 Solbetsuso 150 6.0 〃 Glass flakes 14.1 〃 (Particle size 44μ or less) Total 100.0 〃 Of the above formulation, 16.3 parts by weight of acrylic resin varnish, 3.0 parts by weight of isophorone, Solbetsuso 150
3.0 parts by weight and 14.1 parts by weight of glass flakes were mixed in advance and dispersed using a dispersion machine so that the particle size became 50μ. Next, the remaining ingredients except the blocking isocyanate varnish are mixed and dispersed so that the pigment particle size is 40μ, and then the blocking isocyanate varnish is mixed therein, and the acrylic resin of the glass flakes previously dispersed in this mixture is further added. A blackboard paint was obtained by mixing the varnish dispersion and stirring thoroughly. A blackboard was prepared by painting with this blackboard paint in the same manner as in Example 1. <Example 5> Titanium oxide 2.9 parts by weight Phthalocyanine blue 1.8 〃 Yellow lead 2.6 〃 Fine powder clay 9.5 〃 Precipitated barium sulfate 9.5 〃 Fine powder silica 2.2 〃 Acrylic resin varnish ¹ ) 33.0 〃 (Solid content 50%) Block isocyanate varnish ² ) 14.0 〃 (Solid content 60%) Isophorone 4.1 〃 Solbetsuso 150 4.1 〃 Glass powder 16.3 〃 (Average particle size 30μ) Total 100.0 〃 Of the above formulations, titanium oxide, phthalocyanine blue, yellow lead, fine powder clay, sedimentation Barium sulfate, finely powdered silica, acrylic resin varnish, and isophorone are mixed and dispersed using a dispersion machine so that the pigment particle size is 40μ, then block isocyanate varnish is mixed with this, and glass powder is further stirred at high speed into this mixture. The powder was dispersed into 50μ particles using a grind gauge in a machine to obtain blackboard paint. A blackboard was prepared by painting with this blackboard paint in the same manner as in Example 1. <Example 6> Titanium oxide 2.9 parts by weight Phthalocyanine blue 1.8 〃 Yellow lead 2.6 〃 Fine powder clay 9.5 〃 Precipitated barium sulfate 9.5 〃 Fine powder silica 2.2 〃 Acrylic resin varnish ¹ ) 33.0 〃 (Solid content 50%) Blocked isocyanate varnish ² ) 14.0〃 (Solid content 60 minutes) Isophorone 4.1〃 Solbetsuso 150 4.1〃 Glass fiber 16.3〃〃 (Diameter 10μ, average length 50μ) Total 100.0〃 Among the above ingredients, titanium oxide, phthalocyanine blue, yellow lead, fine powder clay , precipitated barium sulfate, finely powdered silica, acrylic resin varnish, and isophorone were mixed and dispersed using a dispersion machine so that the pigment particle size was 40 μm. Blocking isocyanate varnish was then mixed with this mixture, and glass fiber was added to this mixture. were mixed uniformly using a high-speed stirrer to obtain a blackboard paint. A blackboard was prepared by painting with this blackboard paint in the same manner as in Example 1. <Conventional example> Phthalocyanine blue 1.7 parts by weight Iron oxide yellow 0.8 〃 Furnace carbon black 0.8 〃 Fine powder silica 40.3 〃 Acrylic resin varnish ⁷ ) 32.2 〃 (Solid content 50%) Melamine resin varnish ⁸ ) 11.0 〃 Solbetsuso 150 13.2 〃 Total: 100.0 Of the above formulations, all of the phthalocyanine blue, iron oxide yellow, furnace carbon black, fine powder silica, and acrylic resin varnish were stirred using a high-speed stirrer, and then kneaded using a three-roll mill. The kneading was carried out at least 4 times, and 1/4 of the amount of Solbetsuso 150 was added each time, and kneading was continued until it reached 40μ on a grind gauge.Then, melamine resin was added to this while stirring to obtain a blackboard paint.
Using this blackboard paint, paint in the same manner as in Example 1,
Created a blackboard. <Comparative example> Titanium oxide 3.5 parts by weight Phthalocyanine blue 3.2 〃 Yellow lead 3.1 〃 Fine powder clay 11.4 〃 Precipitated barium sulfate 11.4 〃 Fine powder silica 2.6 〃 Acrylic resin varnish ¹ ) 39.4 〃 (Solid content 50%) Block isocyanate varnish ² ) 16.7 〃 (Solid content 60%) Isophorone 4.7 〃 Solbetsuso 150 4.0 〃 Total 100.0 〃 The formulation of Example 1 except for the glass beads,
That is, in the same manner as in Example 1 with the above formulation, a pigment and an acrylic resin varnish were mixed and dispersed, and then a blocking isocyanate varnish was mixed to obtain a blackboard paint. A blackboard was prepared by painting with this blackboard paint in the same manner as in Example 1. 1 Kotakus SA-105 (manufactured by Toray Industries, Ltd.) 2 Duuranate 17B-60CX (manufactured by Asahi Kasei Industries, Ltd.) 3 Almatex 762LV55A (manufactured by Mitsui Toatsu Chemical Co., Ltd.) 4 Uban 20SE (manufactured by Mitsui Toatsu Chemical Co., Ltd.) 5 Almatex 784 (manufactured by Mitsui Toatsu Chemical Co., Ltd.) 6 Burnotsuk D550 (manufactured by Dainippon Ink Chemical Co., Ltd.) 7 Hitaloid HA2405 (manufactured by Hitachi Chemical Co., Ltd.) 8 Super Betsucomin J820 (manufactured by Dainippon Ink Co., Ltd.) Each of the above examples The following table shows the performance of the blackboards created based on the conventional example and the comparative example.

[Table] Test method (1) Pencil hardness: Hit the painted surface with a Mitsubishi Uni-pencil and find the highest pencil hardness that will not tear the paint film. (2) Ease of writing: Indicates the clarity of characters when written on plaster chalk or dustless chalk (manufactured by Nippon Rikagaku KK). (3) Difficulty in leaving powder behind: Indicates the difficulty in leaving powder behind when erasing letters with a blackboard eraser. (4) Traceability: Indicates whether or not there is no trace left after characters written with a dust eraser are erased with a blackboard eraser. (5) Abrasion resistance: Evaluated by abrasion test and sand eraser resistance. Wear test…CS― by Taber abrasion tester
Abrasion loss in mg when rotated 2000 times with a load of 1 kg using No. 17 abrasion wheel Resistance to sand erasing... Rub the painted surface with your finger using Sand Eraser Lion 502 (manufactured by Fukui Shoji), and the number of reciprocations until the undercoat is visible. Previous As a result of the table, Examples 1 to 3 containing glass beads, Example 4 containing glass flakes, Example 5 containing glass powder,
All of the products of Example 6 containing glass fibers,
In contrast to the dust-resistance yoke, which has good traceability, the hardness of the paint film, and good abrasion resistance, conventional blackboard paints that do not contain glass powder and glass flakes removed from the formulation of Example 1 It is confirmed that the blackboard paint of the comparative example with the same formulation is inferior in the dust stain yoke's ability to leave traces and abrasion resistance.

Claims (1)

[Scope of Claims] 1. Glass beads with a particle size of 80μ or less in the paint component;
Glass powder less than 80μ, thickness 1-7μ, particle size 50
Glass flakes less than 20μ in diameter and 100μ in length
A paint for a blackboard, characterized in that it is made by mixing and dispersing one or more types of glass powder selected from glass fibers having a size of less than μ. 2. A blackboard according to claim 1, characterized in that 15 to 100 parts by weight of glass powder is blended to 100 parts by weight of the total of the solid content of the resin, the main component for forming a coating film, and the extender pigment. paint.