JPH0769627B2 - Transparent film for electrophotography - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transparent film for electrophotography used for projection of overhead projection and the like.

[Conventional technology]

In the electrophotographic method, the transfer of the toner image is good,
In order to obtain high image density, it is necessary that the surface resistivity of the film is within the range of 10 ⁸ to 10 ¹⁴ Ω / mouth, and the thermo-compression roll method is used for toner fixing. In electrophotographic machines, the pressure roll temperature is 200 ° C.
In many cases, the toner fixing layer softens and melts due to this temperature, rubbing scratches to impair transparency, and sometimes the film adheres to the pressure roll. Therefore, the toner fixing layer is required to have sufficient heat resistance to withstand this high temperature.

Further, due to heat from the pressure roll, the base film itself is also softened and deformed by heat, so that phenomena such as waviness and peco do not occur. I won't.

Further, when copying, when the first film is sent out from the toner for running paper during running, the next second film does not stick together and is sent out together, so-called double feeding does not occur, so the toner fixing layer The surface is required to have slipperiness and triboelectrification prevention property, and further, the fixed toner must be firmly adhered to the toner fixing layer, and in order to use it for projection such as overhead projection. , High transparency is required for the coated film.

As described above, in electrophotographic transparent films that are required to be various, as an electrophotographic film that increases image density and is unlikely to cause double feeding, Japanese Patent Publication No. 51-34734 discloses a heat-resistant temperature of 100 ° C. A matting agent having a particle size of 0.05 μm to 20 μm is added to the above plastic film from 0.1% by weight to 5%.
An organic solvent-soluble polyester resin, acrylic acid ester resin, methacrylic acid ester resin, or a copolymer of styrene and methacrylic acid ester, which is contained in a weight percentage of 1 to 10 μm, has been proposed. .
However, although this may have been improved in terms of increasing the image density and making it difficult to cause double feeding, it has drawbacks to be improved when viewed as an electrophotographic film. . That is, the organic solvent-soluble resin group listed here is certainly high in transparency and excellent in adhesion with the toner, but has a problem in heat resistance of withstanding a high temperature of 200 ° C. or higher. However, due to the thermo-compression roll of the copying machine, the toner fixing layer has a drawback in that it is easily melted and fused, and is easily scratched or scratched, resulting in loss of transparency. In order to improve this drawback, there is a means of improving the heat resistance by adding a crosslinking agent such as melamine, isocyanate, or epoxy to the toner fixing layer and changing it to a thermosetting resin. It was found that the strength was significantly reduced.

[Problems to be solved by the invention]

The present invention has been made in view of the above, and sufficiently withstands a high temperature of a thermocompression bonding roll of a copying machine, impairs transparency due to scratches or the like due to melting and softening of a toner fixing layer, and wavy,
To provide a transparent electrophotographic transparent film having heat resistance that does not cause peks, a high image density, and a toner fixing layer to which tows adhere firmly after fixing, and which has excellent running properties. It is a thing.

[Means for solving problems]

The transparent film for electrophotography according to the present invention for solving the above-mentioned problems is an acrylic ester, a methacrylic ester, a styrene-acrylic ester copolymer, a styrene-methacrylic ester on at least one surface of a heat-resistant plastic film. 25 to 90% by weight of a resin component consisting of one or more components selected from acid ester copolymers, polyvinyl butyral and polyester resins, 10 to 75% by weight of silica sol having an average particle size of 3 to 100 mμ, and Made of 0.05 to 5% by weight of a slipperiness-imparting agent and has a thickness of 1 μm to 10 μm.
Toner fixing layer is provided in and at a mu _k (by the measuring method in ASTMD1894) dynamic friction coefficient when the superposed front and back of the film is 0.55 or less, the surface resistivity of the toner fixing layer is ¹⁰⁹ to ¹⁰¹⁴ It is Ω.

The heat resistant plastic film used in the present invention,
It has heat resistance and good transparency, and is, for example, a film made of a resin such as polyethylene phthalate, polycarbonate, cellulose triacetate or other fiber resin, polysulfone, polyether sulfone, polyether ketone, polyarylate or the like. . Further, for the purpose of improving the adhesiveness of the surface of these films to the toner fixing layer, those subjected to corona discharge treatment or anchor treatment may be used.

The resin component used for providing the toner fixing layer is selected from acrylic acid ester, methacrylic acid ester, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, polyvinyl butyral, and polyester resin. One type or two or more types may be used, but these may be any type of coating system such as water-soluble resin coating material, emulsion coating material, organic solvent type coating material. In addition, other resins such as vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, fiber-based resin, polyamide resin, chlorinated olefin resin, etc. may be used for the purpose of improving adhesion and transparency with the base film. You may mix.

The silica sol in the toner fixing layer is a silicon dioxide polymer particle having an average particle size of 3 to 100 mμ, and the surface thereof is dispersed in water in a form of being stabilized with a cation such as sodium ion. It is in the form of an organosol in which the hydroxyl group is made hydrophobic so that it can be dispersed in an organic solvent. Specifically, as water-dispersed silica sol, "Snowtex" (manufactured by Nissan Chemical Co., Ltd.) and "Cataloia" (manufactured by Catalyst Kasei Co., Ltd.) are trade names.
There are "OSCAL" and "OSCAP" as organosols.
(All manufactured by Catalyst Kasei Co., Ltd.), and can be arbitrarily selected depending on the paint system. In addition, silica sol and resin component are
A complex formed by OR bonds, for example, silica-
An acrylic acid ester composite or a silica-styrene-acrylic acid ester composite may be used, or a silica sol may be mixed with these composites.

By mixing the silica sol, the heat resistance of the toner fixing layer is significantly improved. Further, it has the effects of increasing the hardness of the coating film, improving scratch resistance, and lowering the electric resistance value of the surface.

The proportion of silica sol in the toner fixing layer should be in the range of 10 to 75% by weight. That is, if it is less than 10% by weight, the effect of mixing silica sol is hardly exhibited, and
If it exceeds 75% by weight, the coating layer becomes white and the film is not well formed, and cracks easily occur, which makes it brittle against impact, bending and the like.

On the other hand, extensive research results the relationship between the physical properties of the toner fixing layer surface with respect to multi-feed preventing during running, (by the measurement method prescribed in ASTMD1894) dynamic friction coefficient when the superposed front and rear surfaces of the film mu _k is It has been found that when the surface specific resistance value of the toner fixing layer is 0.59 or less and the surface specific resistance value is in the range of 10 ⁹ to 10 ¹⁴ Ω, double feeding does not occur. That is, when the dynamic friction coefficient μ _k exceeds 0.55, double feeding due to insufficient slippage occurs, and when the surface resistivity exceeds 10 ¹⁴ Ω, triboelectrification occurs and the films stick to each other electrostatically to cause double feeding.

As the slipperiness-imparting agent mixed in the toner fixing layer of the present invention, a known slippery agent can be used as long as transparency, heat resistance and toner fixing property are not impaired.

Examples of the slipperiness-imparting agent to be mixed include fluorine-containing polymers such as tetrafluoroethylene polymer and ethylene-tetrafluoroethylene polymer, stearates such as zinc stearate, polyethylene, organic polymers such as polystyrene,
Fine particles of inorganic substances such as silica and alumina, wax, silicon oil, surfactants, vegetable oils, animal oils, mineral oils and the like are used, and among them, fluorinated polymers are most suitable because of their excellent surface lubricity. The amount of the slipperiness-imparting agent added varies depending on the component, but when the fine particle component is mixed, 0.05% by weight to 5.
0% by weight is preferable, if it is less than 0.05% by weight, the effect cannot be exhibited, and if it exceeds 5.0% by weight, the transparency is lowered. The fine particle component may have a particle size of 0.1 to 15 μm. If the particle size is smaller than 0.1 μm, the effect as a slipping agent is insufficient, and if it exceeds 15 μm, the transparency is impaired and the overhead projector When projected by, the shadows of the particles appear on the screen, making them unsightly. In the case of silicone oil, 0.2% by weight
Below, in the case of surfactants, vegetable oils, animal oils, mineral oils, etc., it must be suppressed to 5% by weight or less, and beyond this, the fixability of the toner deteriorates.

Further, the surface electric resistance value of the toner fixing layer shows an antistatic effect by mixing the silica sol of the present invention.
^It drops to ¹⁴ Ω or less, but other conductive resins and antistatic agents can be added if necessary.

[Action]

By mixing silica sol having an average particle diameter of 3 to 100 μm with the coating film component constituting the toner fixing layer of the present invention, when the coating film component is dried and solidified, the hydroxyl groups of the silica sol are dehydrated and condensed, Siloxane bond Si-O-Si
To form a strong three-dimensional network structure. This significantly improves the heat resistant temperature of the toner fixing layer,
A coating film that withstands temperatures of ℃ or above and does not soften and melt. Further, the hardness of the coating film of the toner fixing layer is increased, the scratch resistance is improved, the antistatic effect is obtained, and the surface specific resistance value is lowered within the range of -10 ⁹ to 10 ¹⁴ Ω / mouth. In addition, the silica sol has a particle size of 3 to 100 mμ, and the wavelength of visible light is 400 to 700 m.
Since it was smaller than μ, the transparency of the coating film did not decrease due to light scattering, and the toner adhesion strength after fixing was maintained.

Further, by the function of the slipperiness-imparting agent mixed in the toner fixing layer,
The coefficient of dynamic friction μ _k when the front and back surfaces of the film are superposed is 0.55 or less, and the surface specific resistance value on the toner fixing layer is in the range of 10 ⁹ to 10 ¹⁴ Ω, so double feeding during running also occurs. Absent.

〔Example〕

Hereinafter, typical examples of the present invention will be described. The comparative example is an example to which the present invention is not applied.

Preparation of ethylene tetrafluoride dispersion 25 g of low molecular weight tetrafluoroethylene particles having an average particle diameter of 5 μm (trade name: Lubron L-2, manufactured by Daikin Industries, Ltd.)
Polyethylene glycol octyl phenyl ether 10
After adding 975 g of an aqueous solution containing g and stirring, the mixture is dispersed using a homomixer to prepare a 2.5 wt% dispersion liquid of tetrafluoroethylene particles.

Example 1 A coating solution having the following composition was applied to both sides of a transparent polyethylene terephthalate film having a thickness of 100 μm by using a reverse roll coater and dried in a drying oven at 120 ° C. for 2 minutes.

The obtained film is provided with a toner fixing layer having a thickness of 5 μm on both sides.

Example 2 A coating solution having the following composition was applied to both surfaces of a transparent polycarbonate film having a thickness of 100 μm using a wire bar coater and dried.

The obtained film is provided with a toner fixing layer having a thickness of 4 μm on both sides.

Comparative Example 1 The same operation as in Example 1 was carried out except that the coating liquid of Example 1 was changed to the following formulation.

The obtained film was provided with a coating layer having a thickness of 5 μm on both sides, and 8 wt% of silica sol was contained in the coating layer.
In the same manner as in Example 1, the tetrafluoroethylene particles contained 0.
6% by weight.

Comparative Example 2 From the formulation of the coating liquid of Example 1, ethylene tetrafluoride particles 2.5
The same operation as in Example 1 was performed by using the coating liquid excluding the% dispersion liquid.

The transparent film for electrophotography obtained by each of the above examples was cut into a size of 210 mm × 297 mm (A-4 size),
Actually, electrophotographic copying machines are used to make 100 continuous copies. The results and the physical properties of the film are shown in the table.

As the electrophotographic copying machine, Xerox 4150 (manufactured by Fuji Xerox Co., Ltd.) was used, and the adhesion of the toner in the table was evaluated by a cellotape peeling test and rubbing strongly with a toe.
The heat resistance was evaluated by the presence or absence of scratches on the film surface after copying. The total light transmittance and the haze degree were measured by the measuring method specified in JIS K7105. The surface electric resistance value is
After standing for 24 hours in an environment of 20 ° C. and 65% RH, the value was measured for 1 minute at a voltage of 100V.

[Effects of the Invention] As described above, the transparent film for electrophotography of the present invention has the image density and the toner adhesion without being scratched due to melting and softening by the thermocompression bonding roll at the time of fixing by mixing silica sol. It is a transparent film for electrophotography, which is excellent in transparency, has good slipperiness and antistatic property, does not cause double feeding trouble during copying, and has high transparency.

Claims (1)

[Claims] 1. An acrylic acid ester, a methacrylic acid ester, a styrene-acrylic acid ester copolymer, a styrene-methacrylic acid ester copolymer on at least one surface of a heat-resistant transparent plastic film such as polyethylene terephthalate, polycarbonate, cellulose triacetate and the like. , Polyvinyl butyral, polyester resin, one or two or more components selected from resin components 25 to 90% by weight, average particle diameter 3 to 100 mμ silica sol and / or Si-OR (R: resin (Component) A toner fixing layer comprising 10 to 75% by weight of a composite of a silica sol having a bond and a resin component, and 0.05 to 5% by weight of a slipperiness imparting agent, having a thickness of 1 μm to 10 μm, and the surface of the film. Friction coefficient (when measured according to ASTM D1894) when the upper and lower surfaces are superposed on each other, μK is 0.55 or more A transparent film for electrophotography, characterized in that the surface resistivity of the toner fixing layer below is 10 ⁹ to 10 ¹⁴ .