JP2002372932A - Display board and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display board and a method for manufacturing the board by which formation of pinholes is suppressed as much as possible when toner images are formed on an image recording plate such as a transparent plastic film or the like by an electrophotographic method. SOLUTION: When a toner image formed by an electrophotographic method on a plastic film is heat treated at a temperature at which the melt viscosity of the toner is made to be in the range from 1.0×10<3> Pa.s to 1.0×10<7> Pa.s, pinholes formed in the toner image before the heat treatment can be significantly reduced in number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display panel formed by an electrophotographic method and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as this type of display panel, there is a backlight type display panel formed by forming a color image on a transparent plastic film by an electrophotographic method. The display panel thus configured is used to display the color image on a screen, for example, by being projected from behind by a projector (a so-called OHP).

[0003]

By the way, the technology for forming a color image on a plastic film as in the display panel described above is further developed, and a color toner is fixed on the plastic film to form an image portion and its background portion. The newly formed display panel is configured, and the new display panel is illuminated with a backlight from behind, and only the image section of the display panel is transmitted, so that the image section is displayed. Is technically possible.

Here, unlike the case where such a display panel is used for an OHP, for example, when it is used as an instrument panel for an automobile, good transparency is required for an image portion, and a background portion is required. Good hiding properties are required. Such transparency and hiding properties are adjusted by the colorant concentration in the color toner and the toner mass per unit area on the plastic film, but are generally evaluated by the transmission density, and this transmission density is Transmittance T when irradiating visible light
Is represented by a common logarithm log (1 / T).

[0005] However, even if the image portion and the background portion almost satisfy the preferable transmission density T over the entire surface, if a large number of pinholes exist in the image portion and the background portion, the transmitted light leaks from these pinholes. When such a display panel is used as an instrument panel for an automobile, such a display panel does not satisfy customer satisfaction as a design surface component member and is regarded as a defective product. The pinhole refers to a pin-shaped hole formed because the color toner is not fixed to a portion corresponding to an image portion or a background portion of the plastic film.

Then, when the formation of this pinhole was examined in detail, the following was found. That is, in the current electrophotographic system, since the color toner is heated and melted at about 150 ° C. or more and fixed on the plastic film, an image portion and a background portion on the plastic film are formed in the fixing process. Air in the color toner layer escapes from the color toner layer. For this reason,
In the image area and the background area after the fixing, a circle equivalent diameter of about 0.2
It was found that a large number of pinholes of not more than mm were formed. When the display panel having the image portion and the background portion having the pinholes formed as described above is illuminated by a backlight from behind, the illumination light passes through each pinhole, so that the image quality of the background portion is viewed from the viewpoint of concealment. This leads to an unreliable fatal defect.

In view of the above, the present invention suppresses the formation of pinholes when forming a toner image on an image recording plate such as a transparent plastic film by an electrophotographic method. An object of the present invention is to provide a display panel and a method for manufacturing the display panel.

As a result of the research conducted by the present inventors, a toner image formed on a transparent image recording plate by electrophotography using an electrophotographic toner has a melt viscosity of 1.
If the heat treatment is performed at a temperature within the range of 0 × 10 ³ Pa · s to 1.0 × 10 ⁷ , the number of pinholes formed in the toner image before this heat treatment is determined by the space factor. 1x
It has been found that the amount is greatly reduced to 10 ⁻² % or less.

[0009]

In order to solve the above-mentioned problems, the display panel according to the first aspect of the present invention has at least a background portion formed on a transparent image recording plate by electrophotography. .

In the display panel, the space factor of the pinholes per unit area of the background portion is 1 × 10 ⁻² % or less. Thus, even when the display panel is illuminated, an image can be displayed with high quality without being affected by the pinhole.

A display panel used as a backlight type according to the second aspect of the present invention has at least a background portion formed on a transparent image recording plate by an electrophotographic method. In this display panel, the space factor of the pinhole per unit area of the background portion is 1 × 10 ⁻² % or less. Thereby, even if the display panel used as the backlight type is illuminated by the backlight, the same operation and effect as the first aspect of the invention can be achieved.

Further, as in the invention according to the third aspect, in the invention according to the first or second aspect, if the image recording plate is a plastic film, the operation and effect of the invention according to the first or second aspect can be reduced. It can be achieved even more reliably.

Further, as in the invention according to the fourth aspect, in the invention according to any one of the first to third aspects, if the background portion is subjected to heat treatment, any one of the first to third aspects is provided. The invention described in one aspect can be further improved.

According to the invention described in claim 5, in the invention described in any one of claims 1 to 4, the image portion is formed on the image recording plate by electrophotography in addition to the background portion. The background portion is opaque, and the image portion is translucent. This can also achieve substantially the same operation and effect as the invention according to any one of claims 1 to 4.

Further, according to a method of manufacturing a display panel according to the present invention, a toner is used and an electrophotographic method is used.
At least the background portion is fixed on a transparent image recording plate to manufacture a display plate. In the manufacturing method, the melt viscosity of the toner may be 1.0 × 10 ³ Pa · s to 1.0 ×
At a temperature within a range of 10 ⁷ Pa · s, the background portion fixed on the image recording plate is subjected to a heat treatment.

Thus, the number of pinholes formed in the background portion of the display panel before the heat treatment is reduced by 1 at the space factor.
Significantly reduced to less than × 10 ^-2 %. As a result, it is possible to provide a display panel capable of achieving the operation and effect of the first aspect of the present invention.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a display panel used as a backlight type, wherein at least a background portion is fixed on a transparent image recording plate by electrophotography using toner. It is manufactured as a display panel used as a light type. In the manufacturing method,
The melt viscosity of the toner is 1.0 × 10 ³ Pa · s to 1.0
The background portion fixed on the image recording plate is heated at a temperature within a range of × 10 ⁷ Pa · s. As described above, even when the display panel is used as a backlight type, the same operation and effect as the invention according to claim 6 can be achieved.

According to the invention of claim 8, in the invention of claim 6 or 7, the toner preferably has a melt viscosity of 1.0 × 10 ⁴ Pa · s to 5.0. The value is within a range of × 10 ⁵ Pa · s. Thereby, the function and effect of the invention described in claim 6 or 7 can be further improved.

According to the ninth aspect of the present invention, in the invention according to any one of the sixth to eighth aspects, the binder resin of the toner is a polyester resin, a polystyrene resin, a styrene-acryl resin, It is one of an epoxy resin, a silicone resin, a polyurethane resin and a polyamide resin. Thereby, the function and effect of the invention according to any one of claims 6 to 8 can be further ensured.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a backlight type scale of a vehicle instrument will be described below. In the present embodiment, the scale plate has an arc-shaped scale portion formed as a translucent image portion on the surface of a transparent plastic film, and an opaque portion on the surface of the plastic film except for the image portion. It is configured by forming a background portion. The scale board is illuminated by a backlight from the back side to display the image portion.

Here, the color toner used for forming the image portion and the background portion is mainly composed of a binder resin and a colorant. Examples of the binder resin of the color toner include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, and vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl acetate. , Methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, α-methylene aliphatic monocarboxylic esters such as butyl methacrylate and dodecyl methacrylate, vinyl Homopolymers such as vinyl ethers such as methyl ether, vinyl ethyl ether and vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone; Emissions-based, vinyl ester, alpha-methylene aliphatic monocarboxylic acid esters, copolymers thereof consisting of at least two or more of vinyl ether and vinyl ketone.

In particular, typical binder resins include homopolymers such as polystyrene, polyethylene and polypropylene, or styrene-acrylate copolymers, styrene-methacrylate copolymers, and styrene-acrylonitrile copolymers. And a styrene-butadiene copolymer and a styrene-maleic anhydride copolymer.
Further, typical binder resins include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin, and waxes. Among these, polyester is particularly suitable as the binder resin. For example, a linear polyester resin composed of a polycondensate containing bisphenol A and a polyvalent aromatic carboxylic acid as main monomer components is suitable as the binder resin.

As a typical example of the colorant of the color toner, carbon black is used for black, and C.I. I. Pigment Red 48: 1,
C. I. Pigment Red 122 and C.I. I. Pigment Red 57: 1. As a typical example of the coloring agent, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 12, C.I.
I. Pigment Yellow 180; and cyan, C.I. I. Pigment Blue 15: 1 and C.I. I.
Pigment Blue 15: 3. The above C.I. I. Is an abbreviation for Color Index.

Further, in the backlight type graduation plate referred to in this embodiment, a white colorant is often used in the image area. As this white colorant, titanium oxide, silica, tin oxide,
Examples thereof include aluminum oxide and magnesium oxide, and titanium oxide is preferred from the viewpoint of light resistance. As this titanium oxide, a rutile type, an anatase type or a brookite type is well known, but from the viewpoint of concealment described later, a rutile type titanium oxide is preferable. Further, in order to improve the light resistance, it is desirable that the surface of the rutile type titanium oxide is surface-treated with alumina or silica.

In the case of a backlight type scale plate, transparency is required for a translucent image part, and concealment is required for a background part. Such transparency and hiding properties are determined by the concentration of the colorant in the color toner and the toner mass TMA (Toner Mass) per unit area of the surface of the plastic film.
per Area). In this embodiment, this adjustment takes a value within the range of transmission density T = 0.1 to 1.0 in the image portion, and the transmission density T in the background portion.
= 2.5 or more.

Further, a toner image thermally fixed on a plastic film by an electrophotographic method (image area and background area)
Means that the melt viscosity of the color toner falls within a predetermined melt viscosity range, that is, from 1.0 × 10 ³ Pa · s to 1.0 × 10 ⁷ P
Heat treatment is performed at a temperature within the range of a · s. The reason for keeping the melt viscosity of the color toner within the above-mentioned predetermined melt viscosity range is as follows:
This is because the intermolecular cohesive force of the binder resin is weak and the binder resin relatively easily causes viscous flow. Heating the toner image (image portion and background portion) of the plastic film at a temperature that keeps the melt viscosity of the color toner within the above-described predetermined melt viscosity range as described above for a time of about 10 minutes to 1 hour. Then, the color toner of the toner image is
It was found to flow and fill the pinholes formed in the toner image before the heat treatment. If the melt viscosity is higher than 1.0 × 10 ⁷ Pa · s, the flow of the color toner does not sufficiently occur, and the melt viscosity is 1.0 × 1 Pa · s.
If it is less than 0 ³ Pa · s, the flow of the color toner becomes excessive and the toner image is disturbed.

In the present embodiment, the melting temperature of the color toner for forming the toner image is measured as follows. In this measurement, Shimadzu Corporation CF
A T-500C type flow tester is used, and the color toner extrusion diameter and the extrusion thickness of the nozzle of the flow tester are 0.5 mm and 1.0 mm, and 100 kg.
Is applied to the nozzle. Then, after preheating at an initial set temperature of 70 ° C for a preheating time of 300 seconds, 5 ° C
The melt viscosity of the color toner at each temperature is measured during the process of increasing the temperature at a constant speed per minute.

The pinhole of the toner image is evaluated as follows. This evaluation was made by Nireco F
This is performed using a T-type image processing / analyzing apparatus (product name: Luzex). The toner image is taken from the television camera into the image processing / analyzing device with a visual field of about 500 mm ² , and the total area of the pinhole of the toner image is measured.

According to this, by performing the heat treatment at a temperature within the range of the predetermined melt viscosity as described above, the ratio (occupation ratio) of the pinholes per unit area of the toner image is increased by one. It could be reduced to × 10 ^-2 % or less, and it was found that it could be sufficiently used as a backlight-type scale.

The color toner may contain an additive such as a charge control agent or a wax, if necessary. Examples of the charge control agent include an azo metal complex, a metal complex of salicylic acid or an alkyl salicylic acid, and a metal salt. Examples of the wax include various waxes such as olefins such as low molecular weight polyethylene and low molecular weight polypropylene, plant types such as carnauba, other animal types, and mineral types. The average particle size of the color toner is 30 μm or less, and preferably, a value within a range of 4 μm to 20 μm. Note that a fluidizing agent or the like may be further added to the color toner. Examples of the fluidizing agent include silica, titanium oxide, and aluminum oxide.

The color toner is mixed with an appropriate carrier and used as a two-component electrostatic image developer. Examples of the carrier include ferrite, magnetite, iron powder, or a carrier obtained by coating the surface of the ferrite, magnetite, or iron powder with a coating resin such as a styrene resin, a fluorine resin, a silicone resin, or an epoxy resin. It is also possible to add carbon black or metal oxide-based conductive powder to the coating resin to use it as a semiconductive or conductive carrier. The particle size of the carrier is generally set to a value within the range of 20 μm to 100 μm.

Examples of the transparent plastic film used in the present embodiment include polyethylene terephthalate film, polysulfone film, polyphenylene oxide film, polyimide film, polycarbonate film, cellulose ester film and polyamide film. Among these, a polyethylene terephthalate film is particularly preferred in terms of heat resistance and transparency. When the plastic film is softened by heating at the time of heat fixing by electrophotography, it does not generate wrinkles, and can perform processing such as cutting and punching after forming the toner image. It is necessary to have a thickness. Generally, the thickness of the plastic film is required to be 100 μm or more, preferably 125 μm or more, but the upper limit of the thickness of the plastic film is 200 μm or less in consideration of a decrease in light transmittance. Is preferred.

Hereinafter, a plurality of examples will be described in relation to each comparative example. Here, an electrostatic image developer used in each example and each comparative example was produced as follows. (1) Production of black toner of toner particles A 93% by weight (wt%) of a polyester resin (linear polyester obtained by condensation polymerization of terephthalic acid, bisphenol A ethylene oxide adduct and cyclohexanedimethanol: weight average molecular weight 10,000, Tg) : 68 ° C) and 7 wt
% Carbon black (Mitsubishi Chemical Corp. # 25B) is sufficiently premixed with a Henschel mixer, melt-kneaded with a twin-screw roll mill, cooled, cooled, and then jet milled. Finely pulverized and further classified twice with an air classifier to obtain an average particle size of 8.0.
A μm black toner was produced.

Then, the black toner particles and hydrophobic titanium oxide fine particles having a BET specific surface area of 100 m ² / g as an external additive were mixed at a weight ratio of 100: 0.6 using a Henschel mixer. A black toner of toner particles A was produced. The BET specific surface area refers to a specific surface area per unit mass obtained from an amount of adsorbed nitrogen. (2) Production of Black Toner of Toner Particles B As described above, the carbon black component was changed to 14 wt% among the polyester resin and carbon black components that were premixed by the Henschel mixer, and then the toner particles A The black toner of the toner particles B was manufactured by the same manufacturing process as that for the black toner. (3) Production of White Toner of Toner Particles C As described above, of the components of the polyester resin and the carbon black which are premixed by the Henschel mixer, the carbon black component is replaced by 35 wt% of titanium oxide (Ishihara Sangyo Co., Ltd.) (CR60), and a white toner of the toner particles C was manufactured by the same manufacturing process as that for the black toner of the toner particles A. (4) Production of magenta toner of toner particles D As described above, among the components of the polyester resin and carbon black which are premixed by the Henschel mixer, the component of carbon black is C.I. I. Pigment
Red 122 and C.I. I. Pigment Red 57: 1
Was changed to 15 wt% at a ratio of 3: 2. Under this change, a magenta toner of the toner particles D was manufactured by the same manufacturing process as the black toner of the toner particles A. . (5) Manufacture of carrier Ferrite particles (electrical resistance 1 × 10 ⁹ Ω · cm), toluene, a copolymer of perfluorooctylethyl acrylate and methyl methacrylate, and carbon black (VXC-72 manufactured by Cabot Corp.) The crosslinked melamine resin (average particle size: 0.3 μm) was mixed with 100: 14: 1.
It was prepared at a mass ratio of 6: 0.12: 0.3. However, the copolymer is a copolymer of perfluorooctylethyl acrylate and methyl methacrylate at a copolymerization ratio of 40:60, and the average molecular weight of the copolymer is as follows:
Mw = 50,000.

Ferrite particles among the above four components
The other components are dispersed in a sand mill for 1 hour to form a coating.
Adjust it as a liquid for forming, and
And the particles are placed in a vacuum degassing kneader at 60 ° C. for 3 hours.
After stirring for 0 minutes, the pressure was reduced and the toluene was distilled off.
Forming a coating on the surface of ferrite particles to produce a carrier
did. (6) Each black toner and white toner produced as described above
Black and magenta toners.
Toner, white toner or magenta toner.
And the rear were mixed at a mass ratio of 6:94.
An electrostatic image developer was prepared. And created like this
Each having a thickness of 150 μm using the electrostatic image developer
On the surface of polyethylene terephthalate film
Xerox Co., Ltd. CDT60 type electrophotographic copier
And define the toner image (image area and background area), respectively.
It was made to wear and manufactured as a scale plate. Example 1 On the scale plate, the image area is the white color of the toner particles C.
Using toner, toner mass per unit area (hereinafter, referred to as
Toner mass TMA) = 0.7 mg / cm ^TwoCreate with
Then, the background portion is formed by using black toner of toner particles A.
Knob mass TMA = 1.6 mg / cm^TwoCreated in. this
After forming a toner image as above, at 90 ° C for 45 minutes
Heat treatment was performed. According to this, at 90 ° C.,
The melt viscosity of the white toner in the image area is 2 × 10^FivePa · s
The melt viscosity of the black toner in the background is 1 × 10^FivePa
-It was s. Example 2 On the scale plate, the image area is the white color of the toner particles C.
Using toner, toner mass TMA = 0.7 mg / cm
^TwoThe background is made with black toner of toner particles A.
And the toner mass TMA = 1.6 mg / cm^TwoCreated with
Was. After forming the toner image in this way, at 100 ° C.
Heat treatment was performed for 30 minutes. According to this, 100 ° C
, The melt viscosity of the white toner in the image area is 3 × 10
^FourPa · s, and the melt viscosity of the black toner in the background portion is
2 × 10^FourPa · s. Example 3 On the scale plate, the image portion was formed of the toner particles D
Toner mass TMA = 0.8 mg using black toner
/ Cm^TwoThe background part is the black toner of the toner particles B.
And the toner mass TMA = 1 mg / cm^TwoCreate with
did. After creating the toner image in this way,
For 15 minutes. According to this, 110
At 0 ° C., the melt viscosity of the magenta toner in the image area is
8 × 10 ^ThreePa · s, melting of black toner in background
The viscosity is 4 × 10^ThreePa · s. Comparative example 1 scale
On the board, the image portion is a white toner of toner particles C.
And the toner mass TMA = 0.7 mg / cm^TwoMade with
The background portion is formed by using the black toner of the toner particles A,
Toner mass TMA = 1.6 mg / cm^TwoCreated in. However
However, unlike the above embodiments, the heat treatment after the image creation is
Did not do. Comparative Example 2 Image portion of the dial
Is a toner using the magenta toner of the toner particles D.
Mass TMA = 0.8 mg / cm^TwoAnd the background part is
Using the black toner of the toner particles B, the toner mass TMA
= 1mg / cm^TwoCreated in. However, the above embodiments are
Differently, no heat treatment was performed after image creation.

With respect to the toner images of the respective examples and comparative examples prepared as described above, the pinhole space factor was determined. The results shown in Table 1 below were obtained.

[0037]

[Table 1]

According to Table 1, when the heating process is performed after the toner image is formed as in each of the above-described embodiments, the occupying ratio of the pinholes in the image portion and the background portion is equal to each of the comparative examples. It can be seen that it is very small as compared with the case where the heat treatment after image creation is not performed as shown in FIG.

As described above, after the image portion and the background portion are fixed on the plastic film by the electrophotographic method,
By performing the heat treatment on the image portion and the background portion as described above, the number of pinholes in the image portion and the background portion can be significantly reduced. Therefore, even when the scale plate thus manufactured is illuminated with the backlight, the projected image can be displayed with high quality without being affected by the pinhole.

In the above embodiment, an example in which the predetermined melt viscosity range of the color toner is set to 1.0 × 10 ³ Pa · s to 1.0 × 10 ⁷ Pa · s has been described. The melt viscosity range is more preferably 1.
It is desirable to set the range from 0 × 10 ⁴ Pa · s to 5.0 × 10 ⁵ Pa · s.

In the above embodiment, the transmission density T of the background portion of the scale plate is set to a value of 2.5 or more. However, the transmission density T of the background portion is more preferably
It is desirable to be 3.0 or more.

In implementing the present invention, the image portion
Instead of forming on a plastic film with toner,
A transparent image may be constituted by only the corresponding portion of the plastic film.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kaneishi 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd. Takematsu Office (72) Inventor Norifumi Iida 1600 Takematsu, Minami Ashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd. In-house (72) Inventor Masanori Ichimura 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd.Takematsu Office (72) Inventor Yasuyuki Kobayashi 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. Reference) 2H033 AA45 BA01 BA59 5C096 AA04 AA27 BA01 CA02 CA28 CB01 CC01 EB02 EB16

Claims (9)

[Claims] 1. A display panel having at least a background portion formed on a transparent image recording plate by an electrophotographic method, wherein the space ratio of pinholes per unit area of the background portion is 1
A display panel characterized by being at most × 10 ^-2 %. 2. A display panel used as a backlight having at least a background portion formed on a transparent image recording plate by an electrophotographic method, wherein the space ratio of pinholes per unit area of the background portion is 1%.
A display panel used as a backlight type, characterized in that the content is not more than × 10 ^-2 %. 3. The display plate according to claim 1, wherein the image recording plate is a plastic film. 4. The display panel according to claim 1, wherein the background portion is heat-treated. 5. An image part is formed on the image recording plate by electrophotography in addition to the background part, wherein the background part is opaque and the image part is translucent. The display panel according to any one of claims 1 to 4, wherein: 6. An electrophotographic method using toner.
In a method for manufacturing a display panel wherein at least a background portion is fixed on a transparent image recording plate to manufacture a display panel, the melt viscosity of the toner is from 1.0 × 10 ³ Pa · s to 1.0 × 10 ^7. A method for manufacturing a display plate, wherein a background portion after being fixed to the image recording plate is subjected to a heat treatment at a temperature within a range of Pa · s. 7. An electrophotographic method using toner.
In a method for manufacturing a display panel wherein at least a background portion is fixed on a transparent image recording plate and manufactured as a display panel used as a backlight type, the melt viscosity of the toner is 1.0 × 10 ³ Pa · s to 1 Manufacturing a display panel used as a backlight type, wherein a background portion after being fixed to the image recording plate is subjected to heat treatment at a temperature within a range of 0.0 × 10 ⁷ Pa · s. Method. 8. The melt viscosity of the toner is more preferably from 1.0 × 10 ⁴ Pa · s to 5.0 × 10 ⁵ Pa · s.
The method for manufacturing a display panel according to claim 6, wherein the value is within the range. 9. The toner according to claim 6, wherein the binder resin of the toner is one of a polyester resin, a polystyrene resin, a styrene-acryl resin, an epoxy resin, a silicone resin, a polyurethane resin and a polyamide resin. 9. The method for manufacturing a display panel according to any one of items 1 to 8.