JPS58113944A - Production of electrostatic latent image developer - Google Patents

Abstract

PURPOSE:To produce a titled developer which permits toning and color developing and is suited for jumping developing methods by mixing dyes and pigments with synthetic resins contg. carboxylic groups. CONSTITUTION:After synthetic resins of 5-30 acid values (e.g.; styrene-maleic anhydride copolymer resin) contg. carboxylic groups as well as dyes and pigments are melted and mixed, the mixture is cooled and ground, whereby an electrostatic latent image developer suited for jumping developing methods is obtained. Then the carboxylic groups bound to the terminals or side chains of the synthetic resin molecules are placed in the alternating electric fields applied between a developing member and a latent image holding body, whereby polarization is accelerated and the toner particles assume the state of having large dielectric constants temporarily and jump in the directions of the electric lines of force; therefore, satisfactory development is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a developer used in a non-contact latent image visualization method.

Dry developing methods are the mainstream method for developing electrostatic latent images, and among these, the magnetic brush method is widely used. Since this method is a contact development method, when color development is performed, toners of different tones developed first tend to overlap with the visible image developed first, resulting in mixing of one color. It has the inconvenient problem of blurring.゛Another method of dry development is called the jump method.
Currently, since magnetic component toner is used for F11,
Q% Is it necessary to mix iron oxide, which is a powder, into the toner?
It has been impossible to create toners with tones other than black.

In the present invention, US Pat.
The present invention embodies the idea of making color development possible by producing a toner suitable for a non-magnetic, non-contact development method called the jump method, which is disclosed in No. 90 and others. In this developing method, a developing member is provided at a certain distance from the latent image carrier, and toner particles are spread in a thin layer on the surface of the developing member using, for example, a breaker. An alternating electric field is applied between the developing member and the latent image holder, and the toner particles perform reciprocating motion while jumping between the developing member and the latent image holder 0 due to the action of the alternating electric field.

At this time, the toner particles directed toward the latent image adhere to the latent image due to the electrostatic attraction of the latent image, and the toner particles are removed from the non-image area, thereby completing development.

The toner used in this development method must be uniformly charged either positively or negatively by frictional charging or corona discharge with the surface of the developing member, but an even more important condition is that the developing member and latent image carrier It has the property of changing depending on the alternating electric field applied during the period. We concluded that in order to be transferable, it must have electrical insulation properties, be colored in many tones, and have jump ability. Known resin components for toners include epoxy resins and styrene resins because they are generally easy to control charging polarity.

Polyester resin etc. are used. Usually, these resins are mixed with dyes or specific additives for charging polar funtrols. Synthetic resins into which a unilaterally tangential group has been introduced may have different charging polarity depending on the type of polar group.
4 is already known. However, simply introducing these polar groups is not sufficient to increase the triboelectric charge of the toner.
The reality is that a toner of practical use cannot be obtained without the addition of dyes or specific additives. As a result of investigating the relationship between the carboxyl groups in toner component resins and the jumping phenomenon, the present inventors found that synthetic resins having carboxyl groups are more likely to cause the jumping phenomenon, and other polar groups such as hydroxyl groups, amide groups, sulfone groups, etc. The jump effect was more pronounced than that of 0. It is bonded to the end or side chain of the synthetic resin molecule. Since carboxyl groups promote polarization when placed in an electric field, the toner particles temporarily become in a state with a high dielectric constant, which is thought to increase depending on the direction of the electric field lines. As for types, those that can easily introduce carboxyl groups can be used, such as styrene/acrylic acid ester copolymer resin.

Styrene/maleic acid copolymer resin, polyester resin,
Other examples include: The introduced carboxyl group is not sufficient to control triboelectrification, and must be controlled to exhibit positive or negative properties by mixing dyes or additives. Next, a manufacturing method will be illustrated to specify the composition of the toner.

Example 1 80 g of styrene, 19 g of methyl acrylate, and 1.5 g of acrylic acid were copolymerized to obtain a bulk resin having a softening point of 130° C. and an acid value of 12.

Styrene/acrylic copolymer resin 100g Polyamide resin (Polymide S-40E Sanyo Chemical) 20g
Oil Blue nN (Orient Chemical)
After melt-mixing 10 g of the above blend, cooling and pulverization were performed. The crushed toner has a particle size of 10μ to 20μ.

It was confirmed that triboelectrification with aluminum or iron shows positive polarity. As a result of the development test, it was confirmed that the distance between the developing member and the photosensitive drum could be easily jumped and sufficient development could be performed.

Example 2 97 g of styrene and 3 g of maleic anhydride were copolymerized to obtain a bulk resin with a softening point of 140° C. acid (I ao).

Styrene/maleic anhydride copolymer resin 100
g Polyamide resin (Polymide S-40E Sanyo Chemical)
30g Oil Red ROB-B (Orient Chemical)
10g0g of the above melted mixture, cooled and pulverized to lOμ
A toner having a particle size of .mu.m to .mu.m was obtained. The polarity of frictional charging with aluminum or iron was positive, and it was confirmed that the toner particles were sufficiently jump-developed under the same conditions as in Example 1 for the distance between the developing member and the photosensitive drum.

Example 3 80 g of styrene and 20 g of methyl acrylate were copolymerized to obtain a bulk resin having a softening point of 120°C.

After melt-mixing according to the formulation shown in Example 1, cooling and pulverization were performed to obtain a toner having a particle size of 10 μm to 20 μm.

The polarity of frictional charging with aluminum or iron was positive, but when the alternating electric field between the developing member and the photosensitive drum was the same as in Example 1, the toner particles did not jump, but only when the alternating electric field was doubled. Jump development has started.

Example 4 80 g of styrene and 3 g of methyl acrylate and 7Fly acrylic acid were copolymerized to obtain a bulk resin having a softening point of 145° C. and an acid value of 23.

Styrene/acrylic copolymer resin 10
0g Oil Scarlenoto (Orient Chemical) 5g Permanent Carmine BST (Large m) 10g
The above formulation was melt mixed, cooled and crushed to give 1071-20
A toner with μ particle size was obtained. 0.5wt for this toner
% of fine particles of Nrikakai Aeronlu R-972 (Japan 7 Erosil) were added to the toner and thoroughly mixed. The frictional charge polarity with aluminum or iron was negative. As a result of the development test, an electric field lower than the electric field applied in Example 1 was sufficient for toner particles to jump between the developing member and the photosensitive drum.

Example 5 80g of styrene, 7g of methyl 7glylate + 3g of acrylic acid
g was copolymerized to obtain a bulk resin having a softening point of 145° C. and an acid value of 23.

Styrene acrylic copolymer resin 100 g Carbon blank 5 g Spiron Planok BH (Hodogaya Chemical) 5 g The above formulation was melted and mixed, cooled and crushed.
A toner having a particle size of Oμ to +μ was obtained. The frictional charge polarity with aluminum or iron was negative. Furthermore, as seen in Example 4, by adding 0.5 wt% of fine particle tonica (Aerosil R-972 Nippon Aerosil) to the toner and thoroughly stirring and mixing, the fluidity of the toner was increased and the surface of the developing member was increased. The spraying becomes easier and more uniform. ,
Furthermore, the effect of japping/ping development was as excellent as in Example 4.

The appropriate carboquine group content in the synthetic resin used in the present invention is within the range of acid value 5 to 30.

Since carboxyl groups have the effect of increasing the dielectric polarization of toner particles, it is thought that the use of a synthetic resin containing a large amount of carboxyl groups as a toner component increases the Jambi/G effect of the toner. However, as the acid value increases, the softening point of the resin increases, and the proper r
, temperature adjustment becomes difficult. Since the fixing temperature of toner is generally in the range of 120°C to 150°C, we determined the relationship between the softening point and acid value of synthetic resins that can achieve this temperature range, and found that synthetic resins with high acid values are There was a tendency for the softening point to become higher. In addition, toners using synthetic resins with high acid values tend to have poor fluidity due to a cloud phenomenon that is thought to be caused by agglomeration between toner particles, and toners with poor fluidity tend to cause distortion on the surface of the developing member. When printing, the thickness of the toner layer lacks uniformity, resulting in a loss of uniformity of the image.

In order to satisfy these various properties, the acid value of the synthetic resin used in the toner should be determined within a practical range. In order to determine the appropriate acid value, it is reliable to determine it while actually performing development, and the acid value was determined based on the results.

Patent application agent Takayoshi Koshiki

Claims (1)

[Claims] By using a synthetic resin having a carboxyl group and an acid value of 5 to 30 as the main component, a developer suitable for the jumping development method is obtained, which has a jumping function and can be toned by mixing dyes and pigments. A method for producing an electrostatic latent image developer characterized by: