JPS6345581B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to processing the electrostatic surface of a film-based electrostatic recording medium such as an electrostatic sealless commuter pass.

Conventionally manufactured electrostatic seal-less commuter passes are
For example, as disclosed in JP-A No. 52-105900, low-resistance pigments such as cuprous iodide, zinc oxide, tin oxide, and titanium oxide and thermosetting resin are dispersed and dissolved in an organic solvent and applied. Use as an under layer. The under layer coating surface is then cured by heating.
Demonstrates solvent resistance. Furthermore, a resin solution in which a white pigment such as titanium oxide or calcium carbonate is dispersed is applied onto the hardened underlayer surface using an organic solvent to form a surface layer.

The reason why the under layer paint is based on an organic solvent is that the pigment is dispersed in a high concentration and coated on the film surface.Water-based resins cause repellency, and emulsion-based paints have a high concentration of pigment dispersion. For,
This is because the emulsion will be destroyed.

Furthermore, the reason why a thermosetting resin is used for the under layer is to prevent mixing of both layers when coating the dielectric layer, since the dielectric layer above it is formed using an organic solvent-based paint. , the under layer is thermosetted to provide organic solvent resistance.

On the other hand, cuprous iodide (CuI) as a conductive agent is
As shown in Japanese Patent Publication No. 55-12872, the electrical conductivity is affected by the amount of excess iodine, and when CuI is heated too much, the excess iodine in CuI escapes and the resistance value increases. However, the thermosetting resin used for the under layer usually requires a short time (about 30 minutes) at high temperature (approximately 120°C) or a long time at room temperature to 40°C to cure without losing the excess iodine in CuI. In order to do so, it must be stored for a long time at room temperature to 40°C.

For this reason, it takes about two months to produce an electrostatic recording medium with this structure even when polyurethane resin that hardens at a relatively low temperature is used to form the under layer, and therefore product management and work-in-progress inventory are difficult. There are many problems in terms of cost, pot life due to the curing properties of the paint, checking of the degree of curing after coating, and workability. Furthermore, it also has the disadvantage of not being able to respond to sudden product demands.

The present invention improves the above-mentioned drawbacks, and
Weight average molecular weight as binder resin for under layer
80000~110000, Tg 80~110℃, pencil hardness 2H~
It uses 4H methyl methacrylate resin. This methyl methacrylate resin does not dissolve or swell even when applied with a surface layer paint dissolved in a solvent such as methyl ethyl ketone, toluene, or methyl alcohol.

30 parts by weight of the above methyl methacrylate resin is dissolved in 100 parts by weight of ethyl acetate, and a coating material in which 70 parts by weight of copper iodide is further dispersed is applied to the film in a solid content of 20 to 35 parts by weight.
g/m ² to form an under layer with a surface resistivity of 1 to 5×10 ⁵ Ω. Furthermore, on this under layer, 90 parts by weight of polyester resin, 10 parts by weight of nitrocellulose, 10 parts by weight of titanium oxide, methyl ethyl ketone,
Surface layer paint consisting of 500 parts by weight, solid content 4~
An electrostatic recording material having mesh-like protrusions was obtained by applying 5 g/m ² .

When the obtained electrostatic recording material was recorded, very clear recorded images equivalent to those of conventional products were obtained.

As described above, the electrostatic recording material of the present invention has the following advantages compared to conventional products.

Recording characteristics are the same as conventional products.

Since the under layer is not thermoset, the resistance value is stable and easy to manage.

By not heat-curing the under layer, energy savings and storage periods are significantly shortened, reducing inventory and storage management.

Significantly improved workability during coating.

Reuse of remaining paint.

It is easy to meet product requirements by significantly shortening manufacturing time.

Easy to manage product manufacturing.

Since the resin does not shrink due to heat curing, curling due to internal distortion of the recording medium is eliminated.

As described above, the electrostatic recording medium of the present invention has no difference in recording characteristics in terms of quality, eliminates one factor of curling, saves energy in manufacturing, can produce products in a short period of time, and has improved workability. improves. Furthermore, in terms of management, manufacturing can be done in a short period of time, making it easier to compress and manage processes and inventory.

Next, the present invention will be explained by examples.

Example 1 A polyester film with a thickness of 50 μm was used as a support, and a paint of the following composition was applied on the support by a dry weight of 30 μm.
g/m ² , and an under layer with a surface resistivity of 3×10 ⁵ Ω was provided.

Cuprous iodide 70 parts by weight Methyl methacrylic resin (weight average molecular weight 90,000,
Tg 100℃, pencil hardness 3H) 30 〃 Ethyl acetate 100 〃 On top of the above under layer, apply the following composition solution at a dry weight of 5 g/m ² and dry it to form a dielectric layer that naturally has network-like protrusions. An electrostatic recording medium was obtained in which .

Polyester resin (Toyobo Byron #240)
90 parts by weight Nitrocellulose (Daicel RS-20)
10 〃 Titanium oxide (Ishihara Sangyo Co., Ltd. R-550) 10 〃 Methyl ethyl ketone 500 〃 When the obtained electrostatic recording material was recorded, a very clear image was obtained.

Example 2 A polyvinylidene chloride film with a thickness of 50 μm was used as a support, and a paint having the following composition was applied on it by dry weight.
An under layer with a surface resistivity of 3×10 ⁵ Ω was provided by applying 30 g/m ² .

Cuprous iodide 70 parts by weight Methyl methacrylic resin (weight average molecular weight
105000, Tg 105℃, pencil hardness 4H) 30 〃 Ethyl acetate 100 〃 On top of the above under layer, apply 5 g/m ² of the following composition in terms of dry weight, dry it, and then press it onto an intaglio heated roll to form a mesh. An electrostatic recording material provided with a dielectric layer having protrusions was obtained.

Polyester resin 90 parts by weight Nitrocellulose 10 Methyl ethyl ketone 500 When the obtained electrostatic recording material was recorded, a very clear image was obtained.

Comparative example: A polyester film with a thickness of 50 μm is used as a support, and a coating composition of the following composition is applied on the support at 30 g/dry weight.
m ² coating to provide an under layer with a surface resistivity of 4×10 ⁵ Ω.

Cuprous iodide 70 parts by weight Polyurethane 30〃 Hardening agent 20〃 Tertiary amine 0.5〃 Ethyl acetate 100〃 The under layer coated surface was left at 40℃ for one month, and the coated surface was wiped with a dielectric layer paint solvent. However, the under layer swelled and dissolved, and when the surface layer was applied, swelling and dissolution of the under layer were observed. When the film was further stored at 40°C and a similar test was performed two months later, no change was observed in the under layer, indicating that curing had been completed. The following composition liquid was coated on the under layer coated surface at a dry weight of 5 g/m ² and dried, yielding an electrostatic recording material having a dielectric layer naturally having mesh-like protrusions.

Polyester resin 90 parts by weight Nitrocellulose 10 Titanium oxide 10 Methyl ethyl ketone 500 The obtained electrostatic recording material gave a clear image similar to that of the example, but it had the disadvantage of requiring a long time to manufacture.

Claims (1)

[Claims] 1. On a support made of plastic material, at least one of copper iodide, low-resistance zinc oxide, low-resistance tin oxide, and low-resistance titanium oxide and a binder resin are mainly contained. A low resistance layer is provided and a 5μm layer is placed on top of it.
In an electrostatic recording material provided with a dielectric layer having the following mesh-like protrusions, the binder resin of the low resistance layer has a weight average molecular weight of 80,000 to 110,000, a glass transition temperature (Tg) of 80 to 110°C, a pencil An electrostatic recording material characterized by being a methyl methacrylate polymer having a hardness of 2H to 4H. 2. The electrostatic recording material according to claim 1, wherein the dielectric layer is made of polyester resin and nitrocellulose.