JP2536495Y2 - Erasable sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an erasable sheet, and more particularly to an erasable sheet which can be freely written and erased by various markers and can be copied by an electrophotographic copying machine.

(Prior Art) Conventionally, there has been known a sheet which can be copied by an electrophotographic copying machine and whose surface can be written and erased with a marker.

The above-mentioned conventional sheet has a conductive layer formed on one surface of a fluororesin film having a high dielectric property. In this case, repeated writing and erasing damages the surface, and the erasability is reduced. There's a problem. Further, the surface of the fluororesin film is smooth, the sheets are easily blocked, and the problem of double feeding occurs in the copying machine. Furthermore, since the surface is smooth, there is a problem that the gloss is high and the image is difficult to see depending on the angle.

A similar problem occurs when the entire sheet is made transparent and used as an OHP sheet.

Accordingly, an object of the present invention is to solve the above-mentioned various problems of the prior art, to achieve good copying by a copying machine, and to reduce the erasability even if writing and erasing are repeated by an oily and aqueous marker. It is to provide.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention is characterized in that at least one surface of the insulating support has a cured layer made of an ionizing radiation curable resin containing a fluorine-based additive via a conductor layer, on the cured layer. An erasable sheet that can be repeatedly written and erased and can form an electrophotographic copied image on the cured layer.

(Function) By providing a cured layer of an ionizing radiation-curable resin containing a fluorine-based additive on at least one surface of the support via a conductive layer, writing and erasing can be repeatedly performed and electrophotographic copying can be performed. It becomes a possible erasable sheet.

In a further preferred embodiment, by forming a fine unevenness on the surface of the cured layer, slipperiness with a machine is imparted, and the problem of blocking is eliminated, and the problem of difficulty in viewing an image is also solved.

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to the accompanying drawings which schematically show preferred embodiments.

As shown in FIG. 1, the erasable sheet of the present invention has a support 1
Is characterized in that a cured layer 3 made of an ionizing radiation-curable resin containing a fluorine-based additive is provided on at least one surface of the substrate with a conductive layer 2 interposed therebetween.

The support 1 used for the erasable sheet of the present invention is generally a plastic film having excellent insulating properties. Examples of the support 1 include fluorine resin, polyethylene terephthalate, polyethylene terephthalate / isophthalate copolymer, and polybutylene terephthalate. It is a plastic film or sheet such as polyolefin such as polyester, polyethylene, polypropylene and polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polycarbonate and polyamide, and may have a thickness of several tens μm to several hundred μm. These supports may be transparent or opaque. However, when the object is an OHP sheet, it is necessary to employ a transparent film and furthermore, various layers described below must be transparent.

The conductive layer 2 provided on the surface of the support 1 is a foil or a vapor-deposited layer of a metal such as aluminum, copper, nickel, and silver.
The conductive layer and the support may be integrated by kneading the metal powder as described above into the support, or a coating containing these metals may be applied to the surface of the support and dried to form a coating. You may. When the object is an OHP sheet, a transparent metal oxide layer such as ITO or tin oxide is used for these conductive layers. Since the thickness of these conductive layers differs depending on the structure of the film such as a metal layer and a coating layer, they cannot be unconditionally specified.However, if there is a function capable of quickly neutralizing the electric charge charged on the hardened layer surface during copying, Good.

The cured layer 3 provided on the conductive layer 2 as described above can be cured at room temperature and can form a cured layer having a high crosslinking density to prevent penetration of the marker ink. It is formed from a curable paint and an ultraviolet curable paint.

Electron beam-curable paints and ultraviolet-curable paints are similar in composition except that the latter contains a photopolymerization initiator or a sensitizer, and generally have a structure as a film-forming component. Polymer, oligomer, monomer, etc. having a radical polymerizable double bond or epoxy group in the main component,
It contains a non-reactive polymer, an organic solvent, a wax, and other additives as necessary.

Particularly preferred for the purpose of the present invention, those in which the film-forming component has an acrylate-based functional group, for example, a relatively low-molecular-weight polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, Spiro acetal resin, polybutadiene resin, polythiol polyene resin, oligomer or prepolymer such as (meth) acrylate of polyfunctional compound such as polyhydric alcohol and ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, as reactive diluent Monofunctional monomers such as methylstyrene and N-vinylpyrrolidone and polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate and tripropylene glycol di (meth) acrylate , Diethylene glycol (meth) acrylate, pentaerythritol tri (meth)
Acrylate, dipentaerythritol hexa (meth)
It contains relatively large amounts of acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol (meth) acrylate, and the like.

By using such a polyfunctional (meth) acrylate ionizing radiation-curable paint, a cured layer having excellent surface hardness, transparency, abrasion resistance, abrasion resistance, ink erasability, etc. can be formed. Can be done.

Further, in order to make the above-mentioned curable paint into an ultraviolet-curable paint, acetophenones, as photopolymerization initiators therein,
Benzophenone, Michler benzoyl benzoate, α
-Amiloxime esters, tetramethylthiuram monosulfide, thioxanthones, and n-butylamine, triethylamine, tri-n-butylphosphine and the like as photosensitizers can be mixed and used.

Various types of ionizing radiation curable paints such as the above-mentioned electron beam or ultraviolet curable paints are known, and all of them are easily available from the market and can be used in the present invention.

Conventional techniques can also be used as is for the above-described cured layer, for example, in the case of electron beam curing, Cockloft-Walton type, Bandegraf type, Resonant transformer type, Insulating core transformer type, Linear type, Dynamitron type, High frequency 50 to 1,000 KeV emitted from various electron beam accelerators such as a mold, preferably 100
An electron beam having an energy of about 300 KeV is used. In the case of ultraviolet curing, ultraviolet rays emitted from a light source such as an ultra-high-thickness mercury lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp are used.

The thickness of the cured layer 3 is preferably about 0.5 to 20 μm. If the thickness is too thin, uniform coating is difficult, and the erasability of the ink becomes insufficient. On the other hand, if the thickness is too large, the erasable sheet becomes hard.

In the present invention, a fluorine-based additive is included to impart excellent dielectric properties to the cured layer. As these fluorine-based additives, acrylic monomers and vinyl-based monomers having a fluorine atom can be used. In this case, in addition to the ionizing radiation-curable coating material, polymerization is performed by ionizing radiation curing after forming a coating film. . Other fluorine-based additives include polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkylvinyl ether copolymer, tetrafluoroethylene / hexafluoroethylene copolymer, tetrafluoroethylene / ethylene copolymer, polyvinylidene fluoride And other known fluororesin powders.
These fluorine-based additives are used in the ionizing radiation-curable paint 100.
It is preferred to use 0.5 to 30 parts by weight per part by weight.

In the present invention, on the surface of the cured layer formed as described above,
It is preferable to form the fine irregularities 4 as shown in FIGS. There are various methods for forming the fine unevenness. For example, the fine unevenness 4 is formed on the surface of the hardened layer 3 by using a relatively large amount of the fluorine resin powder 6 as the fluorine-based additive. Method (see Fig. 3), matting agent 7
(See FIG. 4), a method of embossing, and a method of transferring fine irregularities by a shaping film (see FIG. 2).

In the above, a primer layer and an adhesive layer 5 can be provided between the support, the conductive layer, and the cured layer, if necessary.

(Effects) According to the present invention as described above, at least one surface of the support is provided with a cured layer made of an ionizing radiation-curable resin containing a fluorine-based additive via a conductive layer, thereby repeatedly writing and writing. An erasable sheet that can be erased and that can be electrophotographic copied.

In a further preferred embodiment, the problem of blocking by forming a fine uneven shape on the surface of the cured layer,
The problem of the difficulty of seeing the image is solved.

(Example) Next, an example is given and this invention is demonstrated more concretely.

Example 1 Polyester film having a thickness of 50 μm (manufactured by Toray Industries, Inc.
Luminar T-60) has a half-mirror vapor-deposited aluminum layer as a conductor layer, and 100 parts of a polyester acrylate-based UV-curable paint (Seika Beam PHC, manufactured by Dainichi Seika Kogyo Co., Ltd.) An ozone-generating UV lamp 1 with an output of 160 W / cm was applied at a rate of 7 g / m ² as a solid content of a paint containing 4 parts of powder.
Ultraviolet rays were irradiated and cured using a lamp to obtain the erasable sheet of the present invention (see FIG. 1).

Example 2 25 μm thick fluororesin film (Kureha Chemical Co., Ltd.)
After the corona treatment, and after applying a urethane-based primer paint [comprising 1 part of curing agent and 30 parts of a solvent (ethyl acetate / toluene = 1/1) in 15 parts of PET primer manufactured by Dainichi Seika Kogyo Co., Ltd.] , Dried with hot air at 40 ℃, gravure coated with ion conductive urethane resin paint 3μm thick (when dried), and polyester acrylate UV curable paint (Seikabeam PHC, Dainichi Seika Kogyo Co., Ltd.) 100
Part was coated with 4 g of polytetrafluoroethylene powder as a solid content at a rate of 10 g / m ² and the output was 160 W / cm.
UV light was irradiated and cured using one ozone-generating ultraviolet lamp to obtain the erasable sheet of the present invention (see FIG. 1).

Example 3 25 μm thick fluororesin film (Kureha Chemical Co., Ltd.)
), A urethane-based primer coating (PET Primer B, manufactured by Dainichi Seika Kogyo Co., Ltd.) is applied, and then aging is performed at 40 ° C. A body layer is formed, and a polyester acrylate UV curable paint (Seika Beam PH
C, 50 parts of Dainichi Seika Kogyo Co., Ltd.) and 50 parts of a fluorine-based monomer (Osaka Organic Co., Ltd., Biscoat 4F) are added by a gravure reverse method to a dry thickness of 7 μm. , On the surface of which is a shaped film (made by Toray Industries, Inc., PET
X-44), irradiate and cure ultraviolet rays using one ozone-generating ultraviolet lamp with a power of 160 W / cm, and then peel off the above-mentioned shaped film to erase the present invention which has fine irregularities on the surface. A functional sheet was obtained (see FIG. 2).

Example 4 In Example 1, after applying a coating material containing a fluorine-based monomer, the irradiation amount of ultraviolet rays was reduced to half (80 W / cm), embossing was performed in a half-cured state to give fine irregularities, and then an output of 160 W / cm. Irradiate ultraviolet rays using one ozone generating type ultraviolet lamp of 1 cm to completely cure and form a cured layer,
An erasable sheet of the present invention was obtained (see FIG. 2).

Example 5 25 μm-thick fluororesin film (Kureha Chemical Co., Ltd.)
Co., Ltd.) and a urethane-based primer coating (PET primer B, manufactured by Dainichi Seika Kogyo Co., Ltd.)
Then, the same conductive layer as in Example 2 is formed on the primer surface, and 100 parts of a polyester acrylate-based UV-curable paint (Seika Beam PHC, manufactured by Dainichi Seika Kogyo Co., Ltd.) is applied on the primer layer. 8 g of a solid containing a paint containing 1 part of tetrafluoroethylene powder (6 in the figure)
/ m ² , and irradiating and curing ultraviolet rays using one ozone generating ultraviolet lamp having a power of 160 W / cm to obtain an erasable sheet of the present invention having fine irregularities (FIG. 4). reference).

Example 6 25 μm-thick fluororesin film (Kureha Chemical Co., Ltd.)
Co., Ltd.) and a urethane-based primer coating (PET primer B, manufactured by Dainichi Seika Kogyo Co., Ltd.)
Then, the same conductive layer as in Example 2 is formed on the primer surface, and 100 parts of a polyester acrylate-based UV-curable paint (Seika Beam PHC, manufactured by Dainichi Seika Kogyo Co., Ltd.) is applied on the primer layer. 0.7 parts of tetrafluoroethylene powder (6 in the figure), 0.8 parts of styrene beads (7 in the figure) and 0.8 parts of polytetrafluoroethylene wax
Parts was applied at a rate of 8 g / m ² as solids paint added, of the present invention having fine irregularities by UV irradiation and to cure the with ozone-generating ultraviolet lamp 1 lamp of output 160 W / cm An erasable sheet was obtained (see FIG. 4).

Using the erasable sheet of the above example, copying was performed with a commercially available electrophotographic copying machine, and writing was performed on the cured layer with an oil-based marker and a water-based marker. The results shown in Table 1 below were obtained.

[Brief description of the drawings]

FIG. 1 to FIG. 4 are diagrams schematically illustrating the cross section of the erasable sheet of the present invention. 1: support 2: conductive layer 3: cured layer 4: uneven shape 5: primer layer 6: polytetrafluoroethylene particles 7: styrene beads

Claims (3)

(57) [Scope of request for utility model registration] 1. A method according to claim 1, further comprising the step of: providing a cured layer of an ionizing radiation-curable resin containing a fluorine-based additive on at least one surface of the insulating support, with a conductive layer interposed therebetween. An erasable sheet that can be written and erased and can form an electrophotographic copied image on the cured layer. 2. The erasable sheet according to claim 1, wherein fine unevenness is formed on the surface of the cured layer. 3. The erasable sheet according to claim 1, wherein a primer layer and / or an adhesive layer is formed between the respective layers.