JP4583140B2 - Whiteboard - Google Patents

Description

  The present invention relates to a whiteboard capable of repeatedly forming patterns such as ruled lines and grids.

  In recent years, a writing board called a white board has been developed that can be written with a felt pen of water-based or oil-based ink instead of a conventional blackboard and erased by wiping. In this whiteboard, a surface layer such as a melamine-based resin layer or a fluorine-containing resin layer is provided on the surface of a base material so that the surface of this layer can be written and erased with a felt pen or the like.

  Such a whiteboard may be required to be formed with a pattern such as a grid or a ruled line. In such a case, a pattern such as a grid or a ruled line is applied in advance between the base material and the surface layer (see Patent Document 1).

JP-A-10-896 (Claim 1)

  However, a whiteboard on which a pattern such as a ruled line is formed in advance has a problem that the type of ruled line cannot be changed. On the other hand, when a ruled line is not formed in advance but is formed by writing a ruled line with a felt pen or the like, there is a problem that the ruled line disappears together when erasing characters added to the ruled line.

The whiteboard of the present invention that solves the above problems is a whiteboard having a base material, which is a surface capable of erasing writing with a specular gloss of at least one surface of 70% or more, and has a total light transmittance (JIS K7361). −1: 1997) is 60% or more, and haze (JIS K7136: 2000) is 70% or more.

In addition, the light diffusing layer is provided on the base material, and at least one surface of the whiteboard has a specular glossiness of 70% or more and can be written and erased.
  Alternatively, the base material is a light diffusing base material, and at least one surface of the whiteboard has a specular glossiness of 70% or more and can be written and erased.

Further, the writable and erasable surface having a mirror glossiness of 70% or more comprises a writing layer made of a curable resin and a matting agent.

  In the case of the whiteboard of the present invention, when both sides are erasable, the side opposite to the side to be added (hereinafter also referred to as “front side”) (hereinafter referred to as “back side”) In addition, the pattern can be visually recognized from the surface by writing a pattern such as a ruled line or attaching a transparent film on which a pattern such as a ruled line is formed. In addition, when only one surface can be erased by writing, the pattern can be visually recognized from the front surface by attaching a transparent film having a pattern such as a ruled line on the back surface.

  The pattern does not disappear by mistake when erasing characters or the like added to the surface, and the pattern can be changed each time according to the application. In addition, while the pattern such as ruled lines formed on the back surface can be visually recognized, the background cannot be seen through the whiteboard, so it is possible to prevent characters added on the front surface from being confused with the background. be able to. In addition, it has moderate total light transmittance and haze, so when installed near a window, it can make the whiteboard plate surface bright and easy to see even without indoor lighting, and prevents it from becoming difficult to see due to backlight. can do.

  Hereinafter, embodiments of the whiteboard of the present invention will be described.

  The whiteboard of the present invention can be written and erased on at least one side, has a total light transmittance (JIS K7361-1: 1997) of 60% or more, and a haze (JIS K7136: 2000) of 70% or more. It is a feature. The whiteboard of the present invention having such a configuration can be visually recognized from the front surface by writing a pattern such as a ruled line on the back surface or by attaching a transparent film on which a pattern such as a ruled line is formed. . Then, the pattern does not disappear when erasing characters or the like added on the surface, and the pattern can be changed each time according to the use.

  At least one surface of the whiteboard of the present invention is provided with writability and erasability by a whiteboard marker. The writing-erasable surface may be only one surface of the whiteboard, but it is preferable that both surfaces can be erased by writing. By making both sides writable, not only can a transparent film with a ruled line pattern formed on the back side, but also a pattern such as a ruled line can be formed on the back side by writing. Can be done.

  The total light transmittance (JIS K7361-1: 1997) of the entire whiteboard is 60% or more, preferably 80% or more, and the haze (JIS K7136: 2000) is 70% or more, preferably 80% or more. The upper limit of haze is not particularly limited, but is preferably 99% or less.

  By setting the total light transmittance to 60% or more, the pattern formed on the back surface can be visually recognized from the front surface. Further, by setting the haze to 99% or less, the pattern formed on the back surface can be visually recognized more clearly from the front surface. Further, by setting the haze to 70% or more, the background through the whiteboard can be made invisible, and it is possible to prevent characters added on the surface from being confused and becoming difficult to see. Further, by setting the total light transmittance to 60% or more and haze to 70% or more, it is possible to transmit sunlight while diffusing, and when installed near a window, there is no indoor lighting. It is possible to make the whiteboard plate surface bright and easy to see and to prevent the whiteboard plate from being difficult to see due to backlight.

  The writable and erasable surface preferably has a specular gloss (JIS K5600-4-7: 1999) of 70% or more at the lower limit, preferably 135% or less, and preferably 120% or less. More preferred. By setting the specular gloss to 70% or more, it is possible to easily erase characters written with a whiteboard marker. Further, by setting the mirror glossiness to 135% or less, it is possible to prevent reflection of illumination or the like.

  Moreover, it is preferable that the surface of the writing erasable surface has a pencil hardness (JIS K5600-5-4: 1999) HB or higher, more preferably H or higher. By setting the pencil hardness to HB or higher, it is possible to prevent scratches when repeated erasing with a whiteboard marker is repeated.

  Next, the structure and each element of the whiteboard 4 of the present invention will be described. 1-4 is sectional drawing which shows embodiment of the whiteboard 4 of this invention. Each of the whiteboards 4 has at least the base material 1 and has a structure in which at least one surface is a writing-erasable surface 3.

  As the base material 1, various synthetic resin films and synthetic resin plates made of polyethylene terephthalate, polycarbonate, polypropylene, polyethylene, polyvinyl chloride, polyethylene naphthalate, polystyrene, (meth) acrylate resin, fluororesin, etc. Examples thereof include transparent base materials 11 such as various plate glasses made of acid salt glass, phosphate glass, borate glass and the like. Further, a light diffusing substrate 12 in which a transparent base material is melted to contain a light diffusing agent to form a plate or a film, and the transparent base material is subjected to sandblasting, chemical etching, embossing, etc. It can also be used. However, the light diffusive base material tends to be inferior in strength as a base material, and if a relatively thick base material has light diffusibility, it becomes difficult to see the pattern formed on the back surface, A transparent substrate is preferred. Of the transparent substrates, a synthetic resin film or a synthetic resin plate made of a (meth) acrylic acid ester resin having light resistance and high transparency is preferably used. Further, the base material may be formed by bonding two or more base materials together.

  The thickness of the substrate is not particularly limited, but is preferably about 100 μm to 10 mm from the viewpoints of flatness and cost. However, when the substrate is a light diffusing substrate, it is preferably about 100 μm to 3 mm in order to make the pattern formed on the back surface easy to see.

  A light diffusion layer 22 is formed on the substrate 1 as necessary. The light diffusion layer 22 may be directly formed on the base material 1 as shown in FIGS. 2 and 4, or once formed on another base material 21 as shown in FIG. You may form by sticking to the base material 1 through these. Further, the light diffusion layer 22 may be formed not only in one layer but also in two or more layers. The light diffusion layer 22 is preferably formed on the back surface side of the whiteboard 4 with the base material 11 as a reference in order to make the pattern formed on the back surface of the whiteboard 4 easier to see. In other words, the whiteboard 4 preferably uses the light diffusion layer 22 side as the back surface.

  The light diffusion layer is mainly formed from a light diffusion agent and a binder resin.

  As light diffusing agents, inorganic fine particles such as calcium carbonate, magnesium carbonate, barium sulfate, silica, aluminum hydroxide, kaolin, clay, talc, acrylic resin particles, silicone resin particles, polystyrene resin particles, polyurethane resin particles, polyethylene resin Examples thereof include organic fine particles such as particles, benzoguanamine resin particles, and epoxy resin particles. The average particle size of such a light diffusing agent is preferably 1 to 50 μm, and more preferably 3 to 20 μm.

  As binder resins, polyester resins, (meth) acrylic ester resins, polyester acrylate resins, polyurethane acrylate resins, epoxy acrylate resins, cellulose resins, acetal resins, vinyl resins, polyethylene resins, polystyrene Optical resins such as thermoplastic resins, thermosetting resins, ionizing radiation curable resins such as epoxy resins, polypropylene resins, polyamide resins, polyimide resins, melamine resins, phenol resins, silicone resins, fluorine resins, etc. Examples thereof include a resin having transparency. Among these, an acrylic resin having light resistance and high transparency is preferably used.

  The content of the light diffusing agent is preferably 50 to 300 parts by weight and more preferably 80 to 200 parts by weight with respect to 100 parts by weight of the binder resin. By making the content of the light diffusing agent 50 parts by weight or more, the haze can be made 70% or more, and by making it 300 parts by weight or less, the total light transmittance can be made 60% or more.

  The thickness of the light diffusing layer is determined by the average particle diameter and content of the light diffusing agent, and the total light transmittance and haze can be adjusted by adjusting the thickness. Therefore, when the average particle diameter and content of the light diffusing agent described above are taken into consideration, the thickness of the light diffusing layer is preferably 5 to 50 μm, and more preferably 10 to 30 μm. By setting the thickness of the light diffusion layer to 5 μm or more, the haze can be set to 70% or more, and by setting the thickness to 50 μm or less, the total light transmittance can be set to 60% or more and formed on the back surface. The pattern can be made easy to see.

  As the other base material 21, the same materials as those exemplified as the base material 1 can be used.

  The erasable surface 3 is preferably composed of a writing layer 32 made of a curable resin such as a thermosetting resin or an ionizing radiation curable resin and a matting agent. If at least one surface of the whiteboard has a specular gloss of 70% or more, the surface can be erased by writing, and the surface that can be erased does not have to be a writing layer. Therefore, the erasable surface is preferably composed of a writing layer.

  The writing layer 32 is formed on at least one surface of the whiteboard 4 as necessary, and may be formed directly on the base material 1 as shown in FIGS. 2 and 3, or as shown in FIG. Alternatively, it may be formed once on another base material 31 and bonded to the base material 1 via the adhesive layer 33 or the like. Moreover, you may form the writing layer 32 on both surfaces of the white board 4 like FIG. 1, FIG. Further, when the whiteboard 4 has the light diffusion layer 22 and the writing layer 32 is formed only on one surface, as shown in FIG. The writing layer 32 is preferably formed on the surface opposite to the light diffusion layer 22.

  In addition, when forming a writing layer on a light diffusable base material or a light diffusion layer, the surface unevenness | corrugation of a light diffusable base material or a light diffusion layer may be lost, and there exists a possibility that the haze resulting from surface unevenness | corrugation may fall. . Therefore, when the writing layer is formed on the light diffusing substrate or the light diffusing layer, the light diffusing substrate, the light diffusing layer, and the writing layer are partially divided as shown in FIG. It is preferable to stick together. For partial bonding, for example, means for forming a partial adhesive layer by forming the adhesive layer in a lattice shape, a stripe shape, or a dotted shape can be used. Note that even if the haze due to the surface irregularities is reduced, the internal haze caused by the difference in refractive index between the binder resin and the light diffusing agent does not decrease, but when trying to obtain a predetermined haze only with the internal haze, the whiteboard Since the background tends to be transparent and the letters added on the surface tend to be difficult to see, as described above, the means for partially bonding the light diffusing substrate or the light diffusing layer and the writing layer is effective. is there.

  The writing layer is preferably formed of a curable resin such as a thermosetting resin or an ionizing radiation curable resin and a matting agent. As the resin, an ionizing radiation curable resin is particularly preferable. By constituting the writing layer with a curable resin and a matting agent, it is possible to prevent reflection of a writing erasable surface and to make the surface hardness equal to or higher than the pencil hardness HB.

  As the ionizing radiation curable resin, a photopolymerizable prepolymer that can be cross-linked and cured by irradiation with ionizing radiation (ultraviolet ray or electron beam) can be used. As the photopolymerizable prepolymer, 2 per molecule. An acrylic prepolymer having at least one acryloyl group and having a three-dimensional network structure by crosslinking and curing is particularly preferably used. As this acrylic prepolymer, urethane acrylate, polyester acrylate, epoxy acrylate, melamine acrylate and the like can be used. These can be used alone, but it is preferable to add a photopolymerizable monomer in order to further improve the crosslinkability and the hardness of the crosslinked cured coating film.

  As photopolymerizable monomers, monofunctional acrylic monomers such as 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, butoxyethyl acrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol One or two of bifunctional acrylic monomers such as diacrylate, polyethylene glycol diacrylate, and hydroxypivalate ester neopentyl glycol diacrylate, and polyfunctional monomers such as dipentaerythritol hexaacrylate, trimethylpropane triacrylate, and pentaerythritol triacrylate More than seeds are used.

  In addition to the above-mentioned photopolymerizable prepolymer and photopolymerizable monomer, it is preferable to use additives such as a photopolymerization initiator and a photopolymerization accelerator when curing by ultraviolet irradiation.

Examples of the photopolymerization initiator include acetophenone, benzophenone, Michler's ketone, benzoin, benzylmethyl ketal, benzoylbenzoate, α- acyl oxime ester , thioxanthone and the like.

  Further, the photopolymerization accelerator can reduce the polymerization obstacle due to air at the time of curing and increase the curing speed. For example, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, and the like. can give.

  The writing layer may be mixed with other thermoplastic resins or thermosetting resins as long as the effects of the present invention are not impaired.

  Matting agents include inorganic fine particles such as calcium carbonate, magnesium carbonate, barium sulfate, silica, aluminum hydroxide, kaolin, clay, talc, acrylic resin particles, silicone resin particles, polystyrene resin particles, polyurethane resin particles, polyethylene resin particles And organic fine particles such as benzoguanamine resin particles and epoxy resin particles.

  The shape of such a matting agent is not particularly limited, and may be any shape such as an indefinite shape, a true spherical shape, a spherical shape, a scale shape, and a needle shape. The size of the matting agent is not particularly limited because it may be appropriately selected depending on the thickness when the writing layer is formed, and those having a size of about 1 to 20 μm, preferably about 5 to 10 μm are suitably used. The matting agent is preferably selected so that at least a part thereof protrudes from the writing layer. By partially protruding the matting agent from the writing layer, it becomes easy to adjust the specular gloss to 70 to 135%.

  Although the content of the matting agent in the writing layer varies depending on the type of matting agent and the thickness of the writing layer, it cannot be generally stated, but the lower limit is 2 parts by weight or more, preferably 5 parts by weight or more with respect to 100 parts by weight of the binder component. The upper limit is 40 parts by weight or less, preferably 15 parts by weight or less. By setting the content of the matting agent in such a range, the total light transmittance can be 60% or more, and the mirror glossiness can be easily adjusted to 70 to 135%.

  The thickness of the writing layer is determined by the size and content of the matting agent, and the specular gloss can be made specific by adjusting the thickness. Therefore, in consideration of the size and content of the matting agent described above, specifically, the thickness is preferably 2 to 20 μm, and more preferably 5 to 10 μm. By setting the thickness of the writing layer to 2 μm or more, the scratch prevention performance can be made sufficient, and the specular gloss can be made 70% or more. By setting the thickness of the writing layer to 20 μm or less, the specular gloss can be adjusted to 135% or less.

  As a method of adjusting the specular gloss of the erasable surface to 70 to 135%, it can be easily adjusted depending on the content and size of the matting agent contained in the writing layer and the thickness of the writing layer. It is also possible to adjust the writing layer by sandblasting or chemical etching. It is also possible to adjust by embossing a base material made of a plastic film. It is also possible to adjust by forming a writing layer on a film whose surface shape has been adjusted in advance and transferring it to a substrate. In addition, by performing such sandblasting, chemical etching, and embossing directly on the transparent base material, the specular gloss can be adjusted to 70 to 135% without providing a writing layer.

  As the other base material 31, the thing similar to what was illustrated as the base material 1 can be used.

  Examples of the adhesive constituting the adhesive layer include an acrylic pressure sensitive adhesive and a rubber pressure sensitive adhesive. Among these, an acrylic pressure-sensitive adhesive that is not easily yellowed by ultraviolet rays is preferable.

  In the whiteboard of the present invention, the method of adjusting the total light transmittance to 60% or more and the haze to 70% or more includes the type and content of the light diffusing agent contained in the light diffusing layer, and the thickness of the light diffusing layer. Can be adjusted easily. Moreover, it is also possible to adjust by subjecting the base material made of a plastic film to sand blasting, chemical etching, and embossing. Further, the total light transmittance and haze can be finely adjusted by the type and content of the matting agent contained in the writing layer and the thickness of the writing layer.

  The thickness of the entire whiteboard is not particularly limited, but is preferably about 200 μm to 10 mm, and more preferably 1 mm to 6 mm. When the thickness is 200 μm or more, the flatness can be improved, and when the thickness is 10 mm or less, the pattern formed on the back surface can be recognized well.

  You may add additives, such as a crosslinking agent, an antistatic agent, a ultraviolet absorber, antioxidant, a dispersing agent, a leveling agent, in a light-diffusion layer, a writing layer, and an adhesive layer.

  The light diffusing layer, writing layer and adhesive layer are prepared by dissolving or dispersing the constituent components of each layer in an appropriate solvent to prepare a coating solution, and then applying the coating solution to a roll coating method, a bar coating method, a spray coating method, an air knife coating method. It can be formed by applying and drying a transparent substrate or the like by a known method such as curing treatment or ultraviolet irradiation as necessary.

  In the above-described whiteboard of the present invention, if both sides are erasable, do you write patterns such as ruled lines on the side opposite to the side to be added (front side) (back side)? When a transparent film having a pattern such as a ruled line is pasted and used, and only one side can be written and erased, a transparent film having a pattern such as a ruled line is pasted and used on the back side. By using in this way, the pattern formed on the back surface can be visually recognized from the front surface. The pattern does not disappear by mistake when erasing characters or the like added to the surface, and the pattern can be changed each time according to the application.

  The whiteboard of the present invention described above functions as a whiteboard body and can be used by itself, but it is preferable to use the whiteboard by fixing it with a support such as a frame.

  The following examples further illustrate the present invention. “Parts” and “%” are based on weight unless otherwise specified.

1. Preparation of light diffusing film (a) Preparation of light diffusing film a On one surface of a 100 μm thick polyester film (Lumirror T60: Toray Industries, Inc.), the thickness after drying the light diffusing layer coating liquid a having the following formulation is 10 μm. The coating was dried so that a light diffusion layer was formed. Next, an adhesive layer coating solution obtained by diluting an acrylic pressure-sensitive adhesive (Olivein BPS5160: Toyo Ink Co., Ltd.) with a solvent is applied and dried on the other surface of the polyester film so that the thickness after drying is 20 μm. Then, an adhesive layer was formed, and a release film was laminated on the adhesive layer to obtain a light diffusion film a.

<Light diffusion layer coating solution a>
・ Acrylic polyol 10 parts (Acridic A-807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
-Polyisocyanate 2 parts (Takenate D110N: Mitsui Takeda Chemical Company)
(Solid content 60%)
・ Acrylic resin particles 2 parts (Eposter MA1010: Nippon Shokubai Co., Ltd.)
・ 2 parts of silicone resin particles (KMP-701: Shin-Etsu Chemical Co., Ltd.)
・ Methyl ethyl ketone 18 parts ・ Butyl acetate 18 parts

(B) Production of light diffusion film b A light diffusion layer coating solution b having the following formulation was applied to both sides of a 100 μm thick polyester film (Lumirror T60: Toray Industries, Inc.) so that the thickness after drying was 8 μm. It dried and formed the light-diffusion layer. Next, an adhesive layer was formed on one light diffusion layer in the same manner as the light diffusion film a, and a release film was laminated on the adhesive layer to obtain a light diffusion film b.

<Light diffusion layer coating solution b>
・ Acrylic polyol 10 parts (Acridic A-807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
-Polyisocyanate 2 parts (Takenate D110N: Mitsui Takeda Chemical Company)
(Solid content 60%)
・ Calcium carbonate 5 parts (CS-B type: Nippon Lime Industry Co., Ltd.)
・ Methyl ethyl ketone 18 parts ・ Butyl acetate 18 parts

(C) Production of light diffusion film c A polyester film having a thickness of 125 μm (Lumirror S10: Toray Industries, Inc.) was used as a base material, and a white dye (ANP-C-106 white) was used as the light diffusion layer coating liquid b. A light diffusing film c was obtained in the same manner as the light diffusing film a, except that a coating liquid containing 1 part of Toyo Ink Manufacturing Co., Ltd. was used.

(D) Preparation of light diffusion film d Acrylic resin particles and silicone resin particles are removed from the light diffusion layer coating solution a, and 10 parts of barium sulfate (B2: Sakai Chemical Industry Co., Ltd.), titanium dioxide (Tronox R-KB-D) A light diffusion film d was obtained in the same manner as the light diffusion film a, except that 2.5 parts was added.

(E) Production of light diffusion film e Using a 100 μm-thick polyester film (diamat: Kimoto Co., Ltd.) having a thickness of 100 μm as a base material, the light diffusion layer coating solution a to acrylic resin particles and silicone are used as the light diffusion layer coating solution. Except for resin particles, using a coating solution containing 0.5 part of silica (Silicia 450: Fuji Silysia Chemical Co., Ltd.) and changing the thickness of the light diffusion layer to 8 μm, the light diffusion is the same as the light diffusion film a Film e was obtained.

2. Preparation of writing film (f) Preparation of writing film f On one side of a 100 μm thick polyester film (Lumirror T60: Toray Industries, Inc.), a writing layer coating solution f having the following formulation is applied and dried, and then irradiated with ultraviolet light with a high-pressure mercury lamp. Thus, a writing layer having a thickness of 6 μm was formed. Next, an adhesive layer was formed on the other surface of the polyester film in the same manner as the light diffusion film a, and a release film was laminated on the adhesive layer to obtain a writing film f. The specular gloss of the writing layer was 105%.

<Writing layer coating solution f>
・ UV curing type resin 60.0 parts (acrylic resin, solid content 100%)
(Diabeam UR6530: Mitsubishi Rayon Co., Ltd.)
Matting agent (silica, average particle size 4.5 μm) 3.0 parts (Silicia 446: Fuji Silysia Chemical Ltd.)
Pigment (silica, average particle size 30 nm) 3.0 parts (Aerosil R-972: Nippon Aerosil Co., Ltd.)
・ Photopolymerization initiator 0.3 parts
(Irgacure 651: Ciba Specialty Chemicals)
・ Methyl ethyl ketone 80.0 parts ・ Toluene 60.0 parts

(G) Preparation of writing film g Polyethylene is laminated to a fine paper having a basis weight of 110 g / m ^{2 to} a thickness of 30 μm, and quadrangular pyramid-shaped recesses are arranged at intervals of 1 mm in length and width, and the inner diameter of the opening is 0.3 mm. And it formed by embossing so that a depth might be set to 20 micrometers, and the silicone resin was apply | coated to the embossed surface. Next, a pressure sensitive adhesive (BPS-5160: Toyo Ink Manufacturing Co., Ltd.) was applied to the embossed surface at 70 g / m ^{2 and} dried to form an adhesive layer, whereby an adhesive sheet in which the adhesive layer was partially formed was obtained.
Next, a writing layer is formed on one side of a 100 μm thick polyester film (Lumirror T60: Toray Industries, Inc.) in the same manner as the writing film f, and the adhesive sheet is bonded to the other side of the polyester film. g was obtained. The specular gloss of the writing layer was 105%.

[Example 1]
The light diffusion film a was bonded to one surface of an acrylic resin plate (transparent substrate) having a thickness of 5 mm, and the writing film f was bonded to the other surface. Subsequently, the writing film g was bonded together on the light-diffusion film a, and the white board of Example 1 was obtained.

[Example 2]
A white board of Example 2 was obtained in the same manner as Example 1 except that the light diffusion film a was changed to the light diffusion film c.

[Example 3]
The light diffusion film b was bonded to one surface of an acrylic resin plate (transparent substrate) having a thickness of 5 mm, and the writing film f was bonded to the other surface to obtain a white board of Example 3.

[Comparative Example 1]
A white board of Comparative Example 1 was obtained in the same manner as in Example 1 except that the light diffusion film a was changed to the light diffusion film d.

[Comparative Example 2]
A white board of Comparative Example 2 was obtained in the same manner as Example 3 except that the light diffusion film b was changed to the light diffusion film e.

  For the whiteboards obtained in Examples 1 to 3 and Comparative Examples 1 and 2, the haze was measured based on JIS K7136: 2000, the total light transmittance was measured based on JIS K7361-1: 1997, and the haze meter (NDH2000: NEC Corporation). Measured using a decorative company). In the measurement, the back surface of the white board (the surface having the light diffusion layer with respect to the transparent base material) was used as the light incident surface.

  Moreover, the following items were evaluated about the whiteboard obtained by the Example and the comparative example. The results are also shown in Table 1.

(1) Pattern visibility A transparent film with a ruled line pattern is attached to the back of the whiteboard (the surface with the light diffusion layer with respect to the acrylic resin plate as a reference) with an adhesive tape, and the surface of the whiteboard ( The visibility of the ruled line from the surface of the writing film f side) was evaluated visually. The whiteboards of Examples 1 and 2 and Comparative Example 1 were similarly evaluated when a ruled line was written on the back surface of the whiteboard with a whiteboard pen. As a result, “◯” indicates that it can be visually recognized well, and “X” indicates that it cannot be visually recognized in a blurred manner.

(2) Visibility of handwritten characters Characters were added to the surface of the whiteboard (surface on the writing film f side), and the visibility of the characters was visually evaluated from the surface side. As a result, “◯” indicates that the characters are easily visible, and “X” indicates that the characters are difficult to visually recognize due to the background.

(3) Visibility under backlight The same evaluation as the above-mentioned visibility of the handwritten character was evaluated in a state where the whiteboard was placed near the window during the day and the interior lighting was not turned on. As a result, “○” indicates that the whiteboard surface is extremely bright and very easy to see, “△” indicates that the whiteboard surface is slightly bright and looks normal, and “×” indicates that the whiteboard surface is not particularly bright and difficult to see. It was.

  As is clear from the results in Table 1, in Examples 1 to 3, at least one surface can be written and erased, the total light transmittance (JIS K7361-1: 1997) is 60% or more, and haze (JIS). K7136: 2000) is 70% or more, and therefore, the evaluation of the visibility of the pattern, the visibility of the handwritten character, and the visibility in the backlight was excellent.

  Further, in Examples 1 to 3, the pattern formed on the back surface does not disappear when erasing characters added on the front surface, and the back surface pattern can be changed according to the application. It was. In particular, in Examples 1 and 2, since both surfaces were configured to be writable and erased, pattern formation on the back surface could be performed more easily.

  On the other hand, the thing of the comparative example 1 was inferior to the visibility of a pattern and the visibility by backlight, since the total light transmittance is less than 60%.

  In Comparative Example 2, since the haze is less than 70%, it is difficult to see the added letters in the background and it is difficult to diffuse sunlight appropriately, so the whiteboard board surface is brightened. It was inferior to the visibility in backlight.

Sectional drawing which shows one Example of the whiteboard of this invention Sectional drawing which shows the other Example of the whiteboard of this invention Sectional drawing which shows the other Example of the whiteboard of this invention Sectional drawing which shows the other Example of the whiteboard of this invention

Explanation of symbols

1 .... Base 11 ... Transparent Base 12 ... Light Diffusing Base 21, 31 ... Other Base 22 ... Light Diffusion layers 23, 33 ... Adhesive layer 3 ... Writable erasable surface 32 ... Writing layer 4 ... White board

Claims (4)

A whiteboard having a substrate, a writing erasable surface for specular gloss 70% or more of at least one surface, the total light transmittance (JIS K7361-1: 1997) of 60% or more, haze ( JIS K7136: 2000) is 70% or more. 2. The whiteboard according to claim 1, wherein the whiteboard has a diffusion layer on the substrate, and has a specular glossiness of 70% or more on at least one surface of the whiteboard. The whiteboard according to claim 1, wherein the base material is a light diffusing base material, and is a erasable and erasable surface having a specular glossiness of 70% or more on at least one side of the whiteboard . The whiteboard according to any one of claims 1 to 3, wherein the writable and erasable surface having a mirror glossiness of 70% or more comprises a writing layer comprising a curable resin and a matting agent .

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