JPH01293354A - Toner composition - Google Patents

Abstract

PURPOSE:To prevent scratching of a photosensitive body and toner adhesion to it and to enhance cleaning aptitude by adding a fine silicone resin powder to the outside of the toner. CONSTITUTION:The fine silicone resin powder is added to the outside of the toner, and this powder is attached to the surface of each toner particle and intruded between each other. When a cleaning blade is rubbed in a considerable pressure with the surface of the photosensitive body having this toner composition attached, a friction coefficient is effectively alleviated by the excellent lubricity of the silicone resin, thus permitting the toner remaining on the surface of the photosensitive body to be smoothly ranked off without scratching its surface, and melt attaching of the toner to be avoided, and these effects to be obtained even under unfavorable environments of high temperature and high humidity.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a toner composition for developing an electrostatic latent image formed in electrophotography, electrostatic printing, electrostatic recording, etc. The present invention relates to a toner composition having good cleaning properties and fluidity.

(Prior art and its problems) Conventionally, in copiers and the like that utilize electrophotography, electrostatic latent materials formed on photoreceptors of inorganic photoconductors such as selenium, CdS, and ZnO1a-3i and organic photoconductors have been used. In order to visualize images by dry development, various toners in which colorants and the like are dispersed in a fixing resin are used.

In the above development method, an electrostatic latent image formed on the photoreceptor by charging and exposure is developed with the toner, and the developed toner image is transferred to a support such as transfer paper, and a heating roller and a pressure roller are used. The toner image is fixed on the transfer paper and made visible.

After the toner image is transferred to the support, the residual toner on the photoreceptor is often scraped off with a cleaning blade in order to clean the toner remaining on the photoreceptor. In this way, in an electrophotographic copying machine, the image forming process of charging, exposing, developing, transferring, fixing, and cleaning is repeated for each copying operation.The cleaning method using the cleaning blade described above has a simple mechanism, and It is currently used in large quantities because of the advantage that the device can be made smaller.

In this cleaning method, a blade made of a heat-resistant elastic material such as urethane is supported by a support member, and is brought into pressure contact with the photoreceptor surface during cleaning or at any time, and the photoreceptor surface is rubbed by the rotation of the photoreceptor drum. The toner remaining on the surface is scraped off with a blade.

However, in this blade cleaning method, the mechanical friction of the edge of the blade pressed against the photoreceptor surface may damage the photoreceptor surface, and the photoreceptor may be worn out due to repeated rubbing, shortening its lifespan and reducing the quality of the resulting copies. The image becomes inferior.

Therefore, by using a toner composition in which a lubricant is added externally to toner particles, it is possible to reduce the coefficient of friction between the photoreceptor surface and the cleaning blade, thereby preventing scratches and abrasion of the photoreceptor surface. For example, in Japanese Unexamined Patent Publication No. 57-84460, powdered organic resin powder with high lubricity such as fluororesin, polyethylene, polypropylene, polyolefin, polyamide, etc. is added as a lubricant to toner particles. It is proposed that.

(Problems to be Solved by the Invention) However, although the toner composition to which the above-mentioned lubricant made of organic resin powder is added is effective in reducing the coefficient of friction between the cleaning blade and the surface of the photoreceptor,
It tends to reduce the fluidity of toner in the developing device,
Toner scattering due to low charge amount toner due to lack of uniform stirring,
Image fogging, image blurring, etc. occur. In addition, the lubricant powder aggregates and melts due to the frictional heat between the blade and the photoreceptor surface during repeated image formation, and the mixture of toner and lubricant is fused to the photoreceptor surface, resulting in image deterioration. It may cause.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to obtain a good leaning effect and to avoid damaging the surface of the photoreceptor (the blade and the photoreceptor are not damaged). It is an object of the present invention to provide a toner composition that has a reduced coefficient of friction with the surface, does not inhibit the fluidity of toner or developer, and has excellent durability and environmental resistance.

(Means for Solving the Problems) According to the present invention, a toner composition comprising a mixture of toner particles in which additives such as a colorant are dispersed in a fixing resin and a fine silicone resin powder is used. Thus, the problems of the prior art described above are solved and the object of the present invention is achieved.

(Function) The present invention is characterized in that fine powder of silicone resin is externally added to toner particles. A toner composition to which silicone resin fine powder is externally added has silicone resin fine powder on the toner particle surface and between the toner particles, and even if a blade is pressed with considerable pressure against the photoreceptor surface to which this toner composition has adhered. Since the coefficient of friction can be effectively reduced by the excellent lubricity of silicone resin, residual toner can be smoothly scraped off without damaging the photoreceptor. In particular, fine powder of silicone resin has superior water repellency compared to conventional lubricants made of organic resin powder such as fluororesin, polyamide, polyolefin, etc., and has almost no tendency to aggregate, so it It is possible to avoid the phenomenon of fusion to the surface of the photoreceptor, which occurs with organic lubricants and which occurs with a decrease in the fluidity of the developer and an increase in the number of copies. In addition, silicone resin powder exhibits superior water repellency compared to conventional organic lubricants, so it is not affected by humidity and can achieve the above effects even in harsh environments with high temperatures and high humidity. can. In addition, when using the toner composition of the present invention as a two-component developer, the silicone resin fine powder exhibits a large negative triboelectrification property against commonly used carrier particles such as iron powder and ferrite. When used together with a chargeable toner, it is also possible to obtain the effect of preventing toner scattering and image fogging caused by uncharged toner or mechanical impact.

This description will be explained in more detail below.

The particle size of the silicone resin fine powder used in the present invention is generally 0.001 to 10 μm, and preferably 0.1 to 2 μm in order to improve the fluidity of the toner. Further, the shape of the silicone resin fine powder can be any shape within the above particle size range, but spherical fine powder is particularly preferably used because it provides uniform dispersibility in the developer. .

The silicone resin powder can generally be used in an amount of 0.01 to 10 parts by weight per 100 parts by weight of toner particles. In particular, 0.1 to 2 parts by weight is preferable; if it exceeds 10 parts by weight, the toner charge amount increases and problems such as a decrease in image density occur, and if it is less than 0.01 parts by weight, it is difficult to obtain the effects of the present invention. Become.

The silicone resin fine powder that is particularly effective in the present invention is manufactured by Toshiba Silicone Corporation, Tosvar 120.240 (trade name).
It can be obtained from.

The toner particles used in the present invention are those in which additives such as colorants are dispersed in the fixing resin shown below.
Examples of fixing resins include styrene polymers, acrylic polymers, styrene-acrylic polymers, polyethylene chloride, polyprolene, olefin polymers such as ionomers, polyvinyl chloride, polyesters, polyamides, polyurethanes, epoxy resins, and diallyl. Examples include various polymers such as phthalate resin, silicone resin, phenol resin, rosin-modified phenol resin, xylene resin, rosin-modified maleic acid resin, rosin ester, and petroleum resin.

The above polymer has a glass transition point (Tg) of generally 40 to 70°C, particularly 50 to 65°C, and a weight average molecular weight of generally 30,000 to 200,000, particularly 5,000°C.
It is preferably 0 to 150,000, and one type or a mixture of two or more types can be used.

Among the above polymers, rosin esters, rosin-modified phenolic resins, rosin maleic acid resins, epoxy resins, polyesters, cellulose polymers, polyester resins, etc. are useful in improving the triboelectric properties of toner. .

In addition, when the toner is a pressure fixable toner, olefin polymers such as polyethylene and polypropylene, etc.
Polymers that are easily plastically deformed are mainly used. This polymer can be used with other polymers, such as polyvinyl acetate, ethylene-vinyl acetate copolymer, hydrogenated polystyrene, hydrogenated rosin ester, aliphatic, alicyclic or aromatic petroleum It may also contain a resin or the like.

Examples of the coloring agent added to the above-mentioned fixing resin include:
carbon black, lamp black, chrome yellow,
Hansa Yellow, Benzidine Yellow, Permanent Orange, Pyrazolone Orange, Watch Young Red,
Permanent Red, Brilliant Carmine 3B, Brilliant Carmine 6B, DuPont Oil Red, Pyrazolone Red, Lake Red, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue,
Phthalocyanine blue, phthalocyanine green, malachite green offsalate, etc., C1r, 5olve
nt Yellow 60, C, 1,5olven
t Red 27, C.

Examples include oil-soluble dyes such as 1.5olvent Blue 35. These colorants may be used alone or in combination of two or more, and are generally used in an amount of 5 to 60 parts by weight, particularly preferably 15 to 30 parts by weight, per 100 parts by weight of the binder resin.

Further, an anti-offset agent such as wax may be added to the binder resin in order to prevent offset and improve fixing properties. Waxes used include various waxes such as polyethylene wax, polypropylene wax, ethylene-propylene wax, and paraffin wax.
Low molecular weight olefin polymers such as olefin monomers having 4 or more carbon atoms, fatty acid amides, silicone oils, etc. are used.

These anti-offset agents are 0 per 100 parts by weight of binder resin.
．． 1 to 10 parts by weight can be used.

Furthermore, when used as a magnetic toner, it is possible to contain a magnetic substance in the toner, and the magnetic substance may be a material that exhibits magnetism or can be magnetized, such as iron such as ferrite and magnetite, cobalt, etc. , nickel, manganese, and other ferromagnetic metals and alloys are used.

These magnetic substances can be used in an amount of 50 to 200 parts by weight per 100 parts by weight of the fixing resin.

In addition, in order to control the triboelectric charge of the toner, oil-soluble dyes such as nigrosine dye, oil black, spirone black, etc., naphthenic acid, salicylic acid, fatty acids and resin acids such as manganese, iron, cobalt, etc. are added to the binder resin. Metal soaps such as metal salts of lead, zinc, cerium, calcium, nickel, etc., metal alloy azo dyes, pyrimidine compounds, alkyl salicylic acid metal chelates, etc. are added in an amount of 0.00% per 100 parts by weight of the binder resin. 1 to 5 parts by weight, especially 1 to 3 parts by weight are preferably used.

The toner composition of the present invention can be applied to either a one-component developer or a two-component developer. In particular, the toner composition of the present invention can be suitably used in a process in which development is performed by negatively charging a toner.

When used as a two-component developer, various carriers can be used, including magnetic materials such as iron oxide, reduced iron, copper, silicon steel, ferrite, nickel, cobalt, and manganese, zinc, etc. Alloys with aluminum etc., such as magnetic materials such as iron-nickel alloys, iron-cobalt alloys, iron-aluminum alloys; High dielectric constant materials such as titanium oxide, aluminum oxide,
Ceramics such as copper oxide, magnesium oxide, copper oxide, zirconium oxide, silicon carbide, magnesium titanate, barium titanate, lithium titanate, lead titanate, lead zirconate, lithium niobate, ADP, (
NH4Hz POa ), KDP ()()1. p
o,) Rochelle salt etc. are exemplified. One or more of the above carriers may be used.

The particle size of the carrier is preferably 50 to 150 μm, particularly 80 to 100 μm. Note that among the carriers mentioned above, iron such as iron oxide and reduced iron, and ferrite are preferable because they are inexpensive and have excellent image characteristics. The toner composition is prepared by mixing toner particles and fine resin powder in the ratio described above using a mixer commonly used in the past, such as a Henschel mixer or a mixer, and then mixing the toner particles with the above-mentioned hand-held 9A particles.
:99 to 15:85 by weight to prepare a developer.

The present invention will be explained below with reference to Examples and Comparative Examples.

(Example) 100 parts by weight of styrene-acrylic copolymer as a binder resin, 10 parts by weight of carbon black as a coloring agent, 1.0 parts by weight of a negative polar dye as a charge control agent, 1 part by weight of polypropylene as an anti-offset agent After melt-mixing 0.5 parts by weight using a heated roll mill, the mixture was cooled, coarsely pulverized, and classified to obtain a powder toner having an average particle size of 15 μm.

To 100 parts by weight of the above-obtained toner, 1 part by weight of silicone resin fine powder (Tosvar 120, manufactured by Toshiba Silicone Co., Ltd., trade name) having an average particle size of 2 μm was added and mixed to prepare a toner composition. Then, a developer was prepared by adjusting the toner concentration to 4.5% using a ferrite carrier having an average particle size of 80 μm.

(Comparative Example) To a toner similar to the toner of the above example, 1 part by weight of resin powder (Kynar 5201, manufactured by Bensalt Chemical Corporation, trade name) containing vinylidene fluoride as a main component was added per 100 parts by weight of the toner. The mixture was mixed to form a toner composition. Then, in the same manner as in the above embodiment, the toner density is 4.
．． The developer was adjusted to 5%. This was designated as Comparative Developer 1.

Furthermore, a developer having a toner concentration of 4.5% was obtained by adjusting the toner with a carrier without adding a lubricant. This was designated as comparative developer 2.

Then, the developer of each of the above Examples and Comparative Examples was
A 20,000-sheet printing durability test was conducted on a modified copying machine DC-2055 (manufactured by Sanda Kogyo Co., Ltd.) equipped with an organic photoreceptor in a high temperature and high humidity environment of 35°C and 85%, and the photoreceptor was damaged. The following items were evaluated: generation, toner adhesion to the photoreceptor, fluidity, and charging stability. The results are shown in Table-1.

(The following is a blank space) Table 1 Table 1 shows that in harsh environments of high temperature and humidity, fluororesin powder, which has the highest lubricity among organic lubricants and has an excellent cleaning improvement effect, is used as a lubricant. When used, although it is effective in preventing scratches on the photoconductor, the fluidity of the developer decreases as the printing cycle progresses.
The charging characteristics of the toner become unstable. It can also be seen that the aggregation of the lubricant makes it easier for the toner composition to adhere to the photoreceptor. On the other hand, it can be seen that the developer to which the silicone resin fine powder is added and mixed has good cleaning properties and good results in terms of adhesion of the toner composition to the photoreceptor as the printing cycle progresses. Furthermore, it can be seen that the fluidity and charging characteristics of the toner also changed favorably.

(Effects of the Invention) According to the present invention, the toner composition obtained by externally adding and mixing silicone resin fine powder to the toner does not damage the photoreceptor or cause the toner to adhere to the photoreceptor ( It exhibits excellent cleaning properties.It also has excellent heat resistance and condensation properties even in harsh environments of high temperature and humidity, resulting in stable toner fluidity and charging properties, resulting in good development properties.

(Patent applicant: Sanda Kogyo Co., Ltd.)

Claims (1)

[Claims] A toner composition comprising a mixture of toner particles in which additives such as a colorant are dispersed in a fixing resin and fine silicone resin powder.