JPS5828579B2 - Support for recording sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic recording medium that converts and records electrical signals corresponding to characters or figures into electrostatic latent images, or an electronic recording medium that converts optical signals into electrostatic latent images and records them using electrophotography. The present invention relates to conductive supports used in photographic recording media and the like.

The conductive materials conventionally used as supports for electrostatic recording media and electrophotographic recording media include electron conductive conductive agents whose electrical conduction mechanism is based on the movement of electrons or tags, and cationic or anionic conductive agents. Ion-conducting conductive agents are used.

Among these, ion conductive conductive agents include polyvinylbenzyltrimethylammonium salt and polyglycidyltributylphosphonium salt, which are coated or impregnated onto a support to form a conductive layer, and this is applied to the support. The electrostatic recording material and electrophotographic recording material used in the above were able to produce good recorded images when recording was performed under normal environmental conditions.

However, under low humidity environmental conditions of 30% RH or less,
Under conditions of high humidity of %RH or higher, recorded images deteriorate extremely.

This is because the conductivity of ion-conducting conductive agents is greatly affected by humidity; under low humidity conditions, the conductivity decreases, while under high humidity conditions, the conductivity increases, making it difficult to record. This is because the conductivity is below the required level.

Therefore, a support with a conductive layer that does not change in humidity is desired, and it is already known that it is effective to use an electronically conductive conductive agent as a conductive agent. In addition to metals and carbon black, conductive tin oxide and iodized steel are used.

However, in the method of applying an electron-conducting conductive material onto a support, there are metal vapor deposition methods and methods in which metal powder, carbon black, etc. are used as a support, but in general, metal powder or conductive inorganic materials are used. A method is used in which metal compound powder is mixed and dispersed with a binder and the mixture is coated on a support.

In this way, when an electron-conducting conductive agent is used in combination with a binder, the conductivity varies greatly depending on the combination of the conductive agent and binder used, and is one of the most important factors.

The present inventors have found that when a sodium salt of styrene-maleic acid copolymer is combined as a binder with conductive zinc oxide obtained by doping ordinary zinc oxide with other metals such as aluminum, the temperature They discovered that a conductive layer that is most stable against changes in humidity or changes over time can be obtained, and completed the present invention.

In order to make the styrene-maleic acid copolymer solubilized, it can generally be made into a sodium salt or ammonium salt, but among these, the binder used in the present invention is only the sodium salt of the styrene-maleic acid copolymer. It was discovered that this form the most stable conductive layer.

The degree of neutralization with the sodium salt of the styrene-maleic acid copolymer is preferably 100%, but is not particularly limited to 100% as long as water solubility is possible.

It is also possible to use the sodium salt in combination with other salts such as ammonium salts, but desirably it is preferable to contain 50% or more of the sodium salt.

It has been confirmed that the electrical resistance of a conductive layer using a 100% neutralized ammonium salt or other salts as a binder is increased by heating treatment.

This phenomenon is thought to be because the dried film of the ammonium salt of the styrene-maleic acid copolymer is partially crosslinked by heating, thereby inhibiting the movement of electrons.

In the conductive layer made of conductive zinc oxide and styrene-maleic acid copolymer sodium salt, the blending ratio of conductive zinc oxide and styrene-maleic acid copolymer salt is from 95:5 to 70:30. A range of degrees is desirable.

It is also possible to use styrene-maleic acid copolymer sodium salt in combination with other polymeric substances as a binder, but in that case, the content of styrene-maleic acid copolymer sodium salt in the binder must be 50% or more. It is desirable that

It has already been mentioned that the surface resistance of the conductive layer according to the present invention is stable over time and against changes in external conditions. Changes in surface electrical resistance with respect to temperature are shown.

Regarding the humidity change in the conductive layer, one cycle is defined as a change from low humidity (20% RH) to high humidity (80% RH), and the electrical change when repeated 5 cycles is also shown in the same table.

As is clear from these results, the change in electrical resistance of the sodium salt of styrene-maleic acid copolymer is small and stable, but as the amount of ammonium salt increases,
It can be seen that the electrical resistance value tends to increase when stored for a long period of time (6 months) at a temperature of

Typical examples of water-soluble adhesives other than styrene-maleic acid copolymer, emulsion latex, etc. are shown in Table 2, but if the surface resistance becomes high after forming a coating film, , or the temperature gradually increases over time, making it unusable.

Although the cause of this is not fully understood, it is thought that the interaction between the conductive zinc oxide surface and the binder inhibits the movement of electrons that produce conductivity.

The conductive zinc oxide that can be used in the present invention is mainly an n-type semiconductor obtained by doping aluminum, and is a pale bluish-white or pale yellow granule with an average particle diameter of 2μ or less, and is used as an electrode for powder milling by Ando Electric Co., Ltd. The specific resistance value measured with E-31 is 5X
It is less than IO”Ω.

The styrene-maleic acid copolymer is one obtained by copolymerizing styrene with alkaline maleic acid or halfesterized maleic acid, and can be used as a sodium salt or partially solubilized in water as an ammonium salt.

A coating material can be prepared from the conductive zinc oxide and the styrene-maleic acid copolymer by a method that has already been industrialized.

That is, a method in which conductive zinc oxide is dispersed with water using a suitable dispersing machine such as a ball mill, an attritor, a sand mill, or a paint conditioner until the average particle size becomes 5μ or less, and then mixed with a styrene-maleic acid copolymer. ,
Alternatively, it can be prepared by any method in which conductive zinc oxide and styrene-maleic acid copolymer are mixed in advance at a predetermined ratio and then dispersed using the disperser until the particle size becomes 50 μm or less.

The paint thus prepared is applied to one or both sides of paper or film by any conventionally used method such as bar coating, air knife coating, four-roll coating, three-reverse roll coating, etc. A support for a recording sheet can be formed.

The present invention will be explained in more detail below using Examples.

Example l Conductive zinc oxide 60y' Styrene-maleic acid copolymer sodium 50? A paint was prepared by adding 90 grams of water to a paint conditioner and shaking for 10 minutes.

This paint is 52.3P/yy? A conductive layer was formed on one side of a general high-quality paper using a Mayer bar so that the coating weight after drying was 13.01/77I''.

Next, a supercalender treatment is performed so that the surface of the conductive layer has a smoothness of 150 seconds (Beck smoothness).

Furthermore, the following dielectric layer paint was applied on the conductive layer with a coating amount of 6.0? after drying. /m to prepare electrostatic recording paper.

Dielectric layer paint acrylic resin (50% toluene solution) 130P calcium carbonate 35g)'Lz
17 1
65? Add to paint conditioner and shake for 10 minutes to prepare the paint.

When recording paper that had been conditioned by changing the humidity from 25°C, 20% RH to 25°C, 80% RH, was recorded using a high-speed facsimile receiver installed under the same conditions as the humidity control of 4 degrees, good records were obtained at all humidity levels. was gotten.

In addition, this recording paper was tested at room temperature of 60°C and -20'C.
Good records were also obtained when the data were stored for several months.

In addition, from low humidity (25°C 20% RH) to high humidity (25
After 5 cycles of changing humidity (25° C., 20% RH) and low humidity (25° C., 20% RH), recording was performed, and although the recording density was slightly lower, recording was obtained that had no practical problems.

Example 2 1330 g of conductive zinc oxide water 000P was placed in an attritor and dispersed for 20 minutes to form a slurry (60% 5
olids).

The above slurry (60%) 300 (1 styrene-maleic acid copolymer (sodium salt/ammonium salt) 225 (11/1
(20% solution) Thoroughly stir 375 g of water with a homomixer.

The paint thus obtained was coated on one side of 45 g/- general high-quality paper with a dry coating weight of 14. O'? /- to obtain a conductive layer.

The coating amount of ion conductive conductive agent Conductive Polymer 261 on the back side of the conductive layer after drying is 1.0? /rrt, and then supercalendered so that the conductive layer surface has a smoothness of 150 seconds (Beck smoothness).

Next, apply the dielectric layer paint shown below on the conductive layer with a coating amount of 7.0? after drying. /rrt to prepare electrostatic recording paper.

Dielectric layer paint: Add 90 grams of acrylic resin, 241 grams of calcium carbonate, and 86 grams of toluene into a paint conditioner and shake for 10 minutes to condition the paint.

When recording paper that had been conditioned by varying the humidity from 25°C, 20% RH to 25°C, 80% RH, was recorded using a high-speed facsimile receiver installed under the same conditions as the humidity control of 4 degrees, good records were obtained at all humidity levels. Obtained.

After this recording paper was stored for 6 months at room temperature, 60° C., and -20° C., it was similarly recorded under various humidity conditions, and good records were obtained.

Furthermore, from low humidity (25℃ 20% RH) to high humidity (25℃
After 5 cycles of low humidity and humidity change (80% RH), recording was performed, and although the recording density was slightly lower, recording with no practical problems was obtained.

Example 3 Pledis burst clay 40Cl slurry (60% 5olids) Polyvinyl alcohol (10% solution) 501 Acrylic acid emulsion (50%) 01 Water 601 Mix with thorough stirring to prepare paint (I).

This paint is 52. : Coat on one side of general high-quality paper of l/l so that the coated amount after drying is 11'/mf.

Conductive Zinc Oxide 31 Styrene Maleic Acid Copolymer Sodium 31'um salt (20% solution) was added to a paint conditioner and shaken for 10 minutes.
Admonish paint (III).

A base paper is prepared by applying the paint (II) to the back side of the paper coated with the paint (I) so that the coating amount after drying is 101/Trl:.

The base paper is then treated with a supercalender so that the surface coated with paint (I) has a smoothness of 200 seconds (Beck smoothness).

Furthermore, the following photosensitive layer paint is applied on the surface coated with paint (I) to prepare electrophotographic paper.

Oxide layer paint Zinc oxide acrylic resin Infection agent Toluene 170 Guar 2g 5m9 254g was placed in a ball mill and dispersed for 3 hours to prepare the paint.

Recording paper that had been conditioned by varying the humidity from 25°C, 20% RH to 25°C, 80% RH was copied using an electrophotographic copying machine installed under the same conditions as the humidity control of 4 degrees, and from 20% RH to 80% RH. Good records were obtained.

This recording paper was subjected to a storage test and a humidity change cycle test at room temperature of 60° C. Cl 2 O° C. in the same manner as in Example 1, and good recordings were obtained in both cases.

Claims (1)

[Claims] 1. A support for a recording sheet, comprising a conductive layer containing conductive zinc oxide and a sodium salt of a styrene-maleic acid copolymer.