JPH0553363A - Electrophotographic transfer paper - Google Patents

Abstract

PURPOSE:To improve transferability at and under a high temp. and high humidity, etc., and to prevent the splashing of toners by incorporating specific synthetic hectorite which has a specific aspect ratio and, the primary particles of which have the crystal three-layered structure of an extremely fine disk- shaped particles, into the above transfer paper. CONSTITUTION:This transfer paper contains the synthetic hectorite belonging to a limitless layer expansion type trioctahedral which has 20 to 40 aspect ratio and the primary particles of which have the crystal three-layered structure of the extremely fine disk-shaped particles. The structure of such synthetic hectorite consists of formula I or formula II. Further, the synthetic hectorite has X10<9> to 9.9X10<13> specific surface resistance value under environmental conditions of 10 deg.C.20% RH to 35 deg.C.70% RH. This synthetic hectorite contains 0.1 to 5g/m', more preferably 0.2 to 3g/m<2> of the weight of the electrophotographic transfer paper. This synthetic hectorite has a specific conductive characteristic and, therefore, the electrophotographic transfer paper contg. such synthetic hectrorite can maintain the specific surface resistance value under the environmental conditions of a low temp. and low humidity or high temp. and high humidity.

Description

Detailed Description of the Invention

The present invention relates to an electrophotographic transfer paper, and more particularly to a high quality paper type electrophotographic transfer paper used for laser recording electrophotographic copying machines, printers and facsimiles. is there.

[0002]

2. Description of the Related Art An electrophotographic recording system is one in which a photosensitive drum having a surface layer of a photoconductive material and a conductive substrate is charged by irradiation of corona discharge ions, and an image pattern is irradiated on the photosensitive drum as an optical image. The toner is attached to the surface charge image formed on the photosensitive drum to develop the image, the image is transferred to a recording medium, and the image is fixed by heat or pressure to obtain a record.

The electrophotographic system has developed rapidly from a copying machine, has a wide range of applications such as output of a page printer and a facsimile, and is rapidly growing. In particular, in the field of copying machines, progress has been made from an analog system to a digital system, and a color laser copying machine of a digital system has been developed, and a demand for color recording is increasing.

Along with this, there are various required characteristics from the surface of the electrophotographic transfer paper. Required characteristics include running property, transfer property, fixing property, image quality of copy, and appearance.
Some of these properties depend on the properties of the paper itself such as thickness, density, stiffness, smoothness, curl, size, whiteness, gloss, etc.

On the other hand, as a characteristic that affects the running property, transfer property, and image quality, there is a surface specific resistance value of the paper. In particular, in terms of transferability, the transfer rate of toner greatly changes due to the conductivity of the paper. That is, when the surface resistivity is high, the transfer rate is high, and when the surface resistivity is low, the transfer rate is low. The surface resistivity of the paper is controlled by the water content of the paper and the type and amount of the conductive agent added.

The surface resistivity of the paper is related to the water content of the paper and is greatly affected by environmental conditions such as temperature and humidity. Under high temperature and high humidity of 35 ° C. and 70% RH or higher, the surface resistivity of the electrophotographic transfer paper tends to decrease, and in this case, the electric charge necessary for transferring the toner may be retained. This is not possible, and causes a transfer failure. Also, at a low temperature and low humidity of 10 ° C. and 20% RH or lower, the surface specific resistance value of the electrophotographic transfer paper tends to increase, and in this case, the charge accumulated on the photosensitive drum by corona discharge is electrophotographic. Since the transfer paper itself tends to be charged, the amount of charge increases. The charges charged during the transfer and fixing steps flow into the inside of the device via the toner and cause toner scattering.

As described above, for example, JP-A-55-142799 discloses a device in which the surface specific resistance value of the electrophotographic transfer paper is controlled within a certain range under low or high humidity. Here, high-quality paper is made to contain an inorganic salt such as sodium chloride, potassium chloride, sodium nitrate, potassium nitrate or the like to reduce the surface specific resistance value. But,
Under low humidity conditions, the surface resistivity is too high to solve the problem of toner scattering.

[0008]

As described above, in the conventional electrophotographic transfer paper, the surface resistivity is kept constant under the high temperature and high humidity or the low temperature and low humidity environmental conditions that have room for improvement. The problem is to solve the problems of the property of toner and toner scattering.

[0009]

As a result of intensive studies, the present inventor provides an electrophotographic transfer paper which is excellent in transferability under environmental conditions of high temperature and high humidity or low temperature and low humidity and is free from toner scattering. Is.

That is, the electrophotographic transfer paper provided by the present invention has an aspect ratio of 20 to 4 on the electrophotographic paper.
0 and primary particles have a crystal three-layer structure having an ultrafine disc-like particle morphology, and contain synthetic hectorite belonging to an unlimited layer expansion type trioctahedral having an expansion lattice,
The structure of the synthetic hectorite is represented by the following general formula 1) or 2).
It consists of _{1) [Si 8 (Mg 5.34} Li 0.66) O 20 (OH, F) 4] Na + 0.66 2) [Si 8 (Mg 5.34 Li 0.66) O 20 (OH) 4] Na + 0.66

Further, the electrophotographic transfer paper provided by the present invention has a temperature of 10 ° C. and 20% RH to 35 ° C. and 70%.
It has a surface specific resistance value of 1 × 10 ^{9 to} 9.9 × 10 ¹³ Ω under the environmental conditions of RH.

In the electrophotographic transfer paper, the transfer of the toner to the transfer paper requires that the transfer paper uniformly contacts the toner image portion of the photosensitive drum. In that state, it is necessary to make uniform the transfer of toner due to corona discharge from the back surface of the transfer paper. As a result, it is a natural condition to improve the smoothness of the paper surface, but the movement of toner due to corona discharge is
In order to bear the electric potential created on the paper surface, the surface resistivity value of the transfer paper must be within a certain range. When the surface specific resistance value is low, the charge potential of the transfer paper cannot be maintained, and the toner is not moved. On the other hand, when the surface specific resistance value is high, the toner is sufficiently moved, but the potential is too high and the toner image is scattered during the transfer and fixing steps to roughen the toner image.

Under the environmental conditions of high temperature and high humidity or low temperature and low humidity, the specific surface resistivity of the electrophotographic transfer paper is an important condition as described above, but the range is 10 at low temperature and low humidity. 1 × 10 ⁹ Ω at ℃ ・ 20% RH
Above, and at high temperature and high humidity of 35 ° C and 70% RH,
It is 9.9 × 10 ¹³ Ω or less. Here, when the surface specific resistance value under the condition of low temperature and low humidity is less than 1 × 10 ⁹ Ω,
Not enough toner transfer. If the surface resistivity under high temperature and high humidity is 1 × 10 ¹⁴ Ω or more,
Toner is scattered, which is not preferable.

In order to control the surface resistivity of the electrophotographic transfer paper under these environmental conditions, the synthetic hectorite is contained in the electrophotographic paper to stably control the surface resistivity under the environmental conditions. I was able to do it.

The synthetic hectorite has a crystal three-layer structure and is similar to a hectorite belonging to an unlimited layer expanded trioctahedral having an expansion lattice, and its structure is represented by the following general formula 1) or 2). It consists of _{1) [Si 8 (Mg 5.34} Li 0.66) O 20 (OH, F) 4] Na + 0.66 2) [Si 8 (Mg 5.34 Li 0.66) O 20 (OH) 4] Na + 0.66

Specifically, Laporte Indu
stories Ltd. Laponite B under the brand name
S, RD, RDS, XLG, XLS and the like can be mentioned. These are white powders which easily form a sol (Laponite S, RDS, XLS) or gel (Laponite B, RD, XLG) when added to water.

Laponite has a three-layer structure, which is two-dimensionally extended to form platelet particles. Some of the magnesium atoms in the platelet particles are isomorphically substituted with the lower valence lithium, causing charge defects and thus the platelet particles are negatively charged. This negative charge balances the displaceable cation (sodium ion) outside the lattice structure on the surface of the particle plate.

The primary particles of laponite are fine disc-shaped particles, whereas the particles of natural hectorite are rectangular plates. The length of one side of the plate surface is 4
The aspect ratio is 20 to 500 nm.
40. Therefore, when it is used to coat a base paper, it has excellent film-forming properties and is effective in enhancing the smoothness of the paper surface. The same effect can be expected in the case of papermaking.

The primary particles of laponite are secondary agglomerated in a dry state to form a large tabular bundle. When this is dispersed in water, displaceable sodium ions are hydrated and diffused in water, and the particle plate surface is negatively charged. As a result, repulsion between the particles occurs and the particles are dispersed in the primary particles to form a transparent colloidal dispersion. At this time, the end portion of the particle plate adsorbs positive ions by adsorbing cations with respect to the negative charges of the entire small plate.

Such a synthetic hectorite has a disc shape and a three-layer crystal structure, and water can be easily retained between the crystal layers. Therefore, synthetic hectorite has the property of exhibiting conductivity. A synthetic hectorite having conductivity can be an effective material because it can maintain a constant surface specific resistance value under various environmental conditions when it is used for electrophotographic paper.

The synthetic hectorite used in the present invention is
0.1-5 g / m ² to the electronic photographic paper, preferably those containing 0.2 to 3 g / m ^2. The content in the electrophotographic paper can be appropriately changed depending on the method such as coating method, size pressing method, and papermaking method. In the coating method and size pressing method, 0.1 to 3 g / m ² is preferable, and In the papermaking method, ² to 5 g / m ² is preferable. When the content of the synthetic hectorite exceeds 5 g / m ² , the surface specific resistance value becomes too low under low temperature and low humidity conditions to cause transfer failure or absorb water, which is not preferable. Also, 0.1g
If it is less than / m ² , the surface specific resistance value becomes too high under high temperature and high humidity conditions, which causes toner scattering.

The synthetic hectorite has a tabular morphology,
Although it has adhesiveness to the base paper because it has a film-forming property by itself, it is preferable to use an adhesive when coating on one side or both sides of the base paper. It is also preferable to use it in the case of papermaking.

As the adhesive, various commonly used adhesives can be used. For example, starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, acrylic acid amide-acrylic acid ester copolymer, acrylic acid amide-acrylic acid ester-methacrylic acid terpolymer. , A water-soluble adhesive such as an alkali salt of styrene-maleic anhydride copolymer, an alkali salt of ethylene-maleic anhydride copolymer, polyvinyl acetate polyurethane, polyacrylic acid ester, styrene-butadiene copolymer, acrylonitrile- Examples thereof include latex such as butadiene copolymer, methyl acrylate-butadiene copolymer, ethylene-vinyl acetate copolymer and the like.

The electrophotographic paper of the present invention is NBK.
P, LBKP, NBSP, LBSP, GP, TMP and other pulps are mixed and used at a ratio according to the purpose.

The electrophotographic transfer paper of the present invention can be made to contain synthetic hectorite by using the above-mentioned pulp to make a paper by adding synthetic hectorite to pulp slurry and coating it in a size press step. And coating methods such as air knife coating, blade coating, gravure roll coating, curtain coating, and the like, and can be appropriately used depending on the purpose.

[0026]

The electrophotographic transfer paper of the present invention is an electrophotographic paper having an aspect ratio of 20 to 40 and a three-layer crystalline structure in which primary particles have an extremely fine disc-like particle form, and an unlimited layer having an expansion lattice. It contains a synthetic hectorite belonging to the expanded trioctahedral. The synthetic hectorite is
Since it has unique conductivity, the electrophotographic transfer paper containing it can maintain a constant surface specific resistance value under low-temperature low-humidity or high-temperature high-humidity environmental conditions, and has excellent toner transferability. It also has a toner scattering prevention effect.

[0027]

EXAMPLES The present invention will be specifically described below with reference to examples. The present invention is not limited to the embodiments. All parts and percentages below are by weight.

Example 1 Freeness of 380 ml with a refiner c. s. f. LBKP beaten up to 450 ml c. s. f. N beat up
Pulp 100 in which BKP is mixed in a weight ratio of 7: 3
For each part, 7 parts of light calcium carbonate having a primary particle of 1.5 μm (trade name TP121, manufactured by Okutama Industry Co., Ltd.), synthetic hectorite with an aspect ratio of 30 to 40 (trade name Laponite B, Nippon Silica Industry Co., Ltd.). 5 parts, alkyl ketene dimer sizing agent (trade name: Hacon W, manufactured by Dick Hercules) 0.1 part, amphoteric starch 0.8 part, sulfuric acid band 0.8 part, cationic polyacrylamide (product) A paper stock was prepared by adding 0.02 part of Mei High Holder 301, manufactured by Kurita Water Industries Ltd. Hybrid former (Bellform, manufactured by Mitsubishi Heavy Industries) using the produced paper material
And paper making at a paper making speed of 900 m / min, basis weight of 64 g / m ²
To obtain a transfer paper for electrophotography.

Example 2 Freeness of 380 ml with a refiner c. s. f. LBKP beaten up to 450 ml c. s. f. N beat up
Pulp 100 in which BKP is mixed in a weight ratio of 6: 4
For each part, 7 parts of light calcium carbonate having a primary particle of 1.5 μm (trade name TP121, manufactured by Okutama Industry Co., Ltd.) and 0.1 parts of alkyl ketene dimer sizing agent (trade name, Hacon W, manufactured by Dick Hercules). Part, amphoteric starch 0.8
Parts, 0.8 parts of a sulfuric acid band, and 0.02 parts of a cationic polyacrylamide (trade name: High Holder 301, manufactured by Kurita Water Industries Ltd.) were added to prepare a paper stock. A hybrid former (Bellform, manufactured by Mitsubishi Heavy Industries, Ltd.) was used to make paper at a paper-making speed of 900 m / min.
4 g / m ² of electrophotographic paper was obtained. Using the electrophotographic paper obtained here, synthetic hectorite having an aspect ratio of 20 to 30 (trade name Laponite RD, manufactured by Nippon Silica Industry Co., Ltd.)
Was applied to both sides of the electrophotographic base paper by a size press so that the coating amount was 0.1 g / m ² (dry solid content) to obtain an electrophotographic transfer paper.

Example 3 The electrophotographic paper prepared in Example 2 contained 1.5% of primary particles.
45 parts of μm light calcium carbonate (trade name TP121, manufactured by Okutama Kogyo Co., Ltd.), 45 parts of synthetic hectorite with an aspect ratio of 30 to 40 (trade name Laponite B, manufactured by Nippon Silica Kogyo Co., Ltd.), acrylic ester resin emulsion (Product name: Movinyl 987, Hoechst Synthetic Co., Ltd.) Using 10 parts of the coating liquid, a coating amount of 2.5 g / m ² (dry solid content) was applied by gravure roll coating and electronic. A transfer paper for photographs was obtained.

Comparative Example 1 The electrophotographic paper used in Example 2 was used as an electrophotographic transfer paper without being subjected to size pressing with synthetic hectorite.

[0032] Synthetic hectorite (trade name Laponite RD, Nippon Silica Industrial Co., Ltd.) having an aspect ratio of 20 to 30 used in Comparative Example 2 Example 2 except that the the coated amount 0.05 g / m ² Example 2 A transfer paper for electrophotography was obtained in the same manner as.

Comparative Example 3 The coating amount of the electrophotographic transfer paper prepared in Example 3 was 5.5.
A transfer paper for electrophotography was obtained in the same manner as in Example 3 except that g / m ² was used.

The electrophotographic transfer papers prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were conditioned under the environmental conditions of 10 ° C. and 20% RH and 35 ° C. and 70% RH for 5 hours.
The surface specific resistance value of the electrophotographic transfer paper was measured using a surface specific resistance meter 4329A manufactured by Yokogawa Hewlett-Packard Company. The toner transferability and the toner scattering state were measured using the same humidity-controlled electrophotographic transfer paper.
Using a C copying machine (5055, manufactured by Fuji Xerox Co., Ltd.), 1000 sheets were copied and then observed. The results are shown in Table 1. Regarding the toner transferability and toner scattering property, 3 was evaluated as good, 2 was evaluated as slightly good (practical), and 1 was evaluated as poor.

[0035]

[Table 1]

From Table 1 above, in Examples 1 to 3, the surface resistivity values were 1 × 10 ^{9 to} 9.9 × defined in the present invention.
It was in the range of 10 ¹³ Ω, and as a result, the transferability of the toner and the scattering of the toner were good even under the conditions of low temperature and low humidity and high temperature and high humidity. On the other hand, in Comparative Example 1, the synthetic hectorite was not contained, the surface specific resistance value at low temperature and low humidity was high, and the toner scattering property was poor. In Comparative Example 2, the content of the synthetic hectorite is out of the range, and as in Comparative Example 1, the surface specific resistance value at low temperature and low humidity is high, and the toner scattering property is poor. In Comparative Example 3, the content of the synthetic hectorite is large and is out of the range, the surface specific resistance value at high temperature and high humidity is low, and the toner transferability is poor.

[0037]

EFFECT OF THE INVENTION The electrophotographic transfer paper of the present invention has a crystal three-layer structure having an aspect ratio of 20 to 40 on the electrophotographic paper, and the primary particles have an extremely fine disk-like particle form, and has an expansion lattice. It contains a synthetic hectorite belonging to the unlimited layer expansion type trioctahedral, and can maintain a constant surface specific resistance value under low-temperature low-humidity or high-temperature high-humidity environmental conditions, and has excellent toner transferability. It also has a toner scattering prevention effect and is of high practical value.

Claims (2)

[Claims] 1. In electrophotographic transfer paper, the electrophotographic paper has an aspect ratio of 20 to 40, and the primary particles have a crystal three-layer structure having an extremely fine disk-like particle form, and an unlimited layer expansion having an expansion lattice. A transfer paper for electrophotography, which comprises a synthetic hectorite belonging to the type trioctahedral, and the structure of the synthetic hectorite is represented by the following general formula 1) or 2). _{1) [Si 8 (Mg 5.34} Li 0.66) O 20 (OH, F) 4] Na + 0.66 2) [Si 8 (Mg 5.34 Li 0.66) O 20 (OH) 4] Na + 0.66 2. The electrophotographic transfer paper is 10 ° C. and 20%
RH ~ 35 ° C / 70% RH under environmental conditions 1 x 10 ⁹ ~
The electrophotographic transfer paper according to claim 1, which has a surface specific resistance of 9.9 × 10 ¹³ Ω.