JP2746428B2 - Coating carrier - Google Patents

Description

The present invention relates to a carrier constituting a developer used in electrophotography, electrostatic recording, electrostatic printing, and the like. The present invention relates to a coating carrier having a resin coating layer made of a fluorine-containing resin on the surface.

[Prior Art] As a developer used for electrophotography and the like, a two-component developer composed of a toner and a carrier is known.

As a carrier constituting such a developer, conventionally, a coating carrier having a resin coating layer made of a fluorinated resin on the surface of magnetic particles in order to prevent the toner substance from adhering to the carrier surface is used. Known (JP-A-58-208754, JP-A-60-176048,
Nos. 60-16617 and 59-240758.

[Problems to be solved by the invention]

However, in a coating carrier using such a fluorinated resin, the flow characteristics as the particle powder are insufficient, so that the thickness of the developer layer supplied to the development region tends to be uneven, and as a result, the obtained thickness is obtained. In an image, fine line reproducibility and solid image density uniformity are poor, fogging is likely to occur, and especially when performing a generation copy in which a copy image is used as a document and the copy image is further formed. There is a problem that thin lines are likely to occur in the generation.

The present invention has been made in view of the above circumstances, and an object thereof is to be able to form an image with excellent fine line reproducibility and to form an image with excellent density uniformity of a solid image. It is an object of the present invention to provide a coating carrier that satisfies all four conditions, that is, the ability to form an image without fog and the ability to form an image without fine lines in generation copy.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a coating carrier having a resin coating layer made of a fluorinated resin on the surface of magnetic particles, wherein the surface of the resin coating layer contains 0.05 to 0.5 fatty acid alkali metal salt. A configuration in which the content is contained in a percentage by weight is adopted.

That is, the present invention provides a coating carrier having a specific ratio, that is, 0.05 to 0.5% by weight of a fatty acid alkali metal salt, instead of a mere fatty acid metal salt, on the surface of a resin coating layer made of a fluorinated resin. The flow characteristics can be enhanced without adversely affecting the triboelectric charging property, and as a result, a developer layer having a uniform thickness can be supplied to the development area with high accuracy, and the fine line reproducibility is excellent. It is possible to form an image with excellent uniformity of density of a solid image, to form an image without fog, and to form an image without fine line breaks in a generation copy. It is made possible.

In addition, when a fatty acid metal salt other than the fatty acid alkali metal salt is used, as will be understood from the description of a comparative example described later, since the frictional charging property of the coating carrier changes, the frictional charging between the coating carriers causes The flow characteristics of the carrier are greatly reduced, and the above four conditions cannot be satisfied.

The ratio of the fatty acid alkali metal salt contained in the resin coating layer is in the range of 0.05 to 0.5% by weight as described above. However, when the ratio is too small, the flow characteristics of the coating carrier are still insufficient, so The density uniformity of the image is inferior, and thin lines are likely to be cut off in the generation copy. On the other hand, if this ratio is excessive, the adhesiveness of the surface of the coating carrier becomes high and the surface energy becomes high, so that the fine line reproducibility is poor, the uniformity of the density of the solid image is inferior, and the fine line breaks in the generation copy. Cheap.

As a means for containing the fatty acid alkali metal salt on the surface of the resin coating layer, after forming a resin coating layer made of a fluorinated resin on the surface of the magnetic particles, mixed with a fatty acid alkali metal salt powder, Means for adhering powder particles of a fatty acid alkali metal salt on the surface of the resin coating layer can be employed.

This fatty acid alkali metal salt is obtained by reacting a fatty acid with an alkali metal. Examples of the fatty acid include lauric acid, palmitic acid, stearic acid,
Oleic acid and mixtures thereof can be mentioned.
Further, as the alkali metal, lithium, sodium,
Potassium and the like can be mentioned. Among them, particularly preferred are fatty acid salts of lithium, and the effect of improving the flow characteristics of the coating carrier is remarkably exhibited.

The amount of the fatty acid alkali metal salt contained in the resin coating layer made of the fluorinated resin can be quantified as follows. Here, the case where the fatty acid alkali metal salt is potassium stearate will be described.

(1) About 5g of coating carrier in 100cc beaker
Put in and stir.

(2) An appropriate amount of acetone is added thereto, and a magnet is arranged at the bottom of the beaker to fix the coating carrier to the bottom of the beaker by magnetic force so that the coating carrier does not flow out, and only the resin coating layer is eluted.

(3) The operation of (2) is repeated to completely elute the resin coating layer.

(4) Dry the magnetic particles remaining in the beaker on a hot plate.

(5) Measure the total weight of the magnetic particles.

(6) The coverage is determined from the following equation.

A: Total weight of the coating carrier B: Total weight of the magnetic particles (7) On the other hand, about 100 g of the coating carrier is put into one beaker, this is stirred, and the operation of (2) is repeated to form the resin coating layer. Elute.

(8) The solvent is removed from the eluted solution using an evaporator, and the solution is further dried under reduced pressure.

(9) The remaining resin is pelletized, and the amount of potassium stearate in the resin is quantified by elemental analysis such as X-ray fluorescence analysis.

(10) The content M of potassium stearate in the coating carrier is determined from the following equation.

C: coverage (% by weight) defined by the above formula D: amount of potassium stearate in the resin (% by weight) The fluorine-containing resin constituting the resin coating layer is described in JP-A-64-9470. Polyvinylidene fluoride, polytetrafluoroethylene, polyvinylidene fluoride-tetrafluoroethylene copolymer as described, for example, acrylic acid-1,1-dihydroperfluoroethyl polymer, acrylic acid-1,1, Use a resin having a group in which a fluorine atom is substituted in a side chain, such as a copolymer of 3-trihydroperfluoro-n-propyl and 1,1-dihydroperfluoro-n-propyl acrylate. be able to. The thickness of the resin coating layer is about 0.5 to 3.0 μm.

As the magnetic particles serving as the core material of the coating carrier, conventionally used magnetic particles can be used, and specific examples thereof include particles of ferrite, magnetite, and the like.

〔Example〕

Hereinafter, Examples of the present invention will be described together with Comparative Examples,
The present invention is not limited to these embodiments. In the following, “parts” means “parts by weight”.

Comparative Example 1 12 g of a fluorinated resin / ethylene fluoride / tetrafluoroethylene copolymer was mixed with acetone / methyl ethyl ketone (1
/ 1) The coating solution was prepared by dissolving in 500 ml of a mixed solvent.

Using this coating solution, a resin coating layer having an average thickness of about 2 μm was formed on the surface of the spherical ferrite particles by a spira coater to obtain a coating carrier a for comparison.

Comparative Example 2 In Comparative Example 1, the coating liquid was changed to 1,1-dihydroperfluoroethyl acrylate polymer 1, which is a fluorinated resin.
A resin coating layer was formed in the same manner except that the coating solution was prepared by dissolving 2 g in 500 ml of acetone, to obtain a coating carrier b for comparison.

Comparative Example 3 A coating solution was prepared by dissolving 15 g of a styrene / methyl methacrylate copolymer in 300 ml of methyl ethyl ketone, and using this coating solution, an inner layer having an average film thickness of 1 μm was formed on the surface of the spherical ferrite particles by a spira coater. did.

Next, acrylic acid-1,1,3-
Trihydroperfluoro-n-propyl / acrylic acid-
1,1-dihydroperfluoro-n-propyl copolymer 12 g
Was dissolved in 500 ml of acetone to prepare a coating solution, and using this coating solution, an outer layer was formed on the surface of the inner layer by a Spira coater, thereby forming a resin coating layer having a total average thickness of about 2 μm, A coating carrier c for comparison was obtained.

Example 1 Comparative coating carrier c obtained in Comparative Example 3
1 kg of lithium stearate and 1 g of lithium stearate, "Micro-type see-through mixer" as a V-type mixer (manufactured by Tsutsui Rikagaku Co., Ltd.)
The mixture was mixed at a rotation speed of 70 rpm for 20 minutes to obtain a coating carrier 1 in which the surface of the resin coating layer contained lithium stearate.

Example 2 In Example 1, the amount of lithium stearate was changed to 500 m
In the same manner except that g was changed, coating carrier 2 having lithium stearate contained on the surface of the resin coating layer was obtained.

Comparative Example 4 In Example 1, the amount of lithium stearate was changed to 200 m
A comparative coating carrier d in which lithium stearate was contained on the surface of the resin coating layer was obtained in the same manner except that g was changed to g.

Example 3 In Example 1, a coating carrier c for comparison was used.
Was changed to a coating carrier a for comparison, to obtain a coating carrier 3 in which lithium stearate was contained on the surface of the resin coating layer.

Example 4 In Example 1, a coating carrier c for comparison was used.
Was changed to a coating carrier b for comparison to obtain a coating carrier 4 in which the surface of the resin coating layer contained lithium stearate.

Comparative Example 5 In the same manner as in Example 1, except that lithium stearate was changed to zinc stearate, a comparative coating carrier e in which zinc stearate was contained on the surface of the resin coating layer was obtained.

Comparative Example 6 In the same manner as in Example 1, except that the amount of lithium stearate was changed to 7 g, a comparative coating carrier f containing lithium stearate on the surface of the resin coating layer was obtained.

Example 5 A coating carrier 5 in which potassium stearate was contained on the surface of the resin coating layer was obtained in the same manner as in Example 1, except that lithium stearate was changed to potassium stearate.

Example 6 In the same manner as in Example 1, except that lithium stearate was changed to potassium palmitate, a coating carrier 6 in which the surface of the resin coating layer contained potassium palmitate was obtained.

Example 7 A coating carrier 7 containing lithium stearate on the surface of the resin coating layer was obtained in the same manner as in Example 1 except that the amount of lithium stearate was changed to 5 g.

<Actual photo test> Each carrier obtained in the above examples and comparative examples,
Each two-component developer was prepared by mixing the toner and the toner at a ratio of 4% by weight. The used toner was obtained as follows.

That is, 100 parts of styrene / methyl methacrylate / butyl acrylate copolymer resin and carbon black 1
0 parts and 3 parts of polypropylene were mixed, kneaded, pulverized,
After classification, a powder having an average particle size of 10 μm was obtained. Further, 100 parts of this powder and 0.8 parts of hydrophobic silica fine particles were mixed with a Henschel mixer to obtain a toner.

Using each of the above two-component developers, an actual photographing test was performed by an electrophotographic copying machine “U-Bix 1017” (manufactured by Konica Corporation), and the following items were evaluated.

Fine line reproducibility The copied image was visually observed, and the number of fine lines per 1 mm that could be reproduced well was examined and judged. The larger the number, the better the fine line reproducibility.

Density Uniformity of Solid Image A 5 cm × 5 cm solid original having an original density of 1.3 was copied, and the density ratio between the maximum density portion and the minimum density portion of the copied image was checked to determine. The closer this density ratio is to 1, the higher the uniformity of the solid image.

Fine line breakage in generation copy When forming a generation copy, it was determined by examining how many generations a fine line image of 5 lines / mm could be reproduced well.

Here, the “generation copy” means that a copy image is formed by using a copy image formed first as a document and further repeating the operation of forming the copy image.

 The results are as shown in Table 1.

As understood from Table 1, according to the coating carriers of Examples 1 to 7, it is possible to form an image having excellent fine line reproducibility, and to form an image having an excellent solid image density uniformity. This makes it possible to form an image without breaks in fine lines in a generation copy.

On the other hand, according to the coating carriers of Comparative Examples 1 to 3, since the fatty acid alkali metal salt is not contained at all, the reproducibility of fine lines is inferior, the uniformity of solid image density is inferior, and the fine lines in Cutting easily occurs.

According to the coating carrier of Comparative Example 4, since the content ratio of the fatty acid alkali metal salt is too small, the reproducibility of fine lines is inferior, the uniformity of density of a solid image is inferior, and the thin lines are liable to be cut off in a generation copy.

According to the coating carrier of Comparative Example 5, since the fatty acid alkaline earth metal salt was contained instead of the fatty acid alkali metal salt, the triboelectric charging property of the coating carrier was changed, the fine line reproducibility was poor, and the density of the solid image was low. The uniformity is poor, and thin lines are likely to be cut off in the generation copy.

According to the coating carrier of Comparative Example 6, since the content ratio of the fatty acid alkali metal salt is excessive, the reproducibility of fine lines is inferior, the uniformity of density of a solid image is inferior, and the thin lines are liable to be cut off in a generation copy.

Further, when the coating carriers of Examples 1 to 7 were used, the presence or absence of fogging was examined. As a result, no fogging was observed.

〔The invention's effect〕

According to the present invention, since a specific ratio of a fatty acid alkali metal salt is contained on the surface of the resin coating layer made of a fluorinated resin, it is possible to enhance the flow characteristics of the coating carrier without adversely affecting the triboelectric charging property of the coating carrier. As a result, the developer layer can be supplied to the development area in a uniform thickness state, an image having excellent fine line reproducibility can be formed, and an image having excellent solid image density uniformity can be obtained. It is possible to form an image without fogging, and further, to form an image without fine line breaks in a generation copy.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-64-9470 (JP, A) JP-A-64-33559 (JP, A) JP-A-58-216261 (JP, A) JP-A-2- 2579 (JP, A) JP-A-2-27365 (JP, A) JP-A-1-180563 (JP, A)

Claims (1)

(57) [Claims] 1. A coating carrier having a resin coating layer made of a fluorinated resin on the surface of magnetic particles, wherein the surface of the resin coating layer contains 0.05 to 0.5% by weight of a fatty acid alkali metal salt. A coating carrier characterized by comprising: