JPS6320345B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improved binder for electrophotographic toners.

Conventionally, binders for electrophotographic toners include thermoplastic resins with softening points in the range of approximately 80 to 120°C, such as polystyrene resins, epoxy resins, terpene resins, acrylic resins, and styrene resins.
Acrylonitrile copolymer resins, styrene-acrylic copolymer resins, etc. are used, but toner compositions using these binders tend to aggregate during storage, resulting in reduced fluidity such as cake-like formation and toner particles. In addition to poor sliding between the gaps, changes in humidity can greatly affect the triboelectric properties and flow properties, making it difficult to clarify the shading of the image, the edges of the image becoming unclear, and causing fogging. may occur.

In order to solve these drawbacks, attempts have been made to add lubricants such as silicone oil, silicone varnish, and metal soap to prevent agglomeration and caking during storage and to provide lubricity between toner particles. However, in this case, the additive component bleeds to the surface of the toner particles and becomes unevenly distributed, making it impossible to obtain sufficient effects.

On the other hand, in recent years, as electrophotography has become faster, it has become necessary to increase the fixing speed of toner for electrophotography, and for this reason, it is necessary to improve the release rate between the toner and the rubber roll used for fixing the toner. However, by using the above additives, satisfactory results cannot be obtained due to bleeding and the like.

The present inventors completed the present invention as a result of intensive research in order to improve these drawbacks. [R ¹ in the formula is a hydrogen atom or a methyl group, Q
is the expression (where R ² is a monovalent hydrocarbon group having no aliphatic unsaturated group, m is an integer of 1 to 3, n is an integer of 1 to 10, a is 0, 1 or 2), p
and q is a positive number, 100≦p+q≦2000, 0.01<p/p+q≦0.3], and (b) 1 part by weight of a silicon atom-containing copolymer resin having a softening point of 80 to 120°C. The present invention relates to a binder for an electrophotographic toner comprising 0 to 5 parts by weight of a silicon atom-free thermoplastic resin within the range.

The toner composition prepared using the binder of the present invention does not aggregate during storage and maintains excellent fluidity, has good lubricity between toner particles, and is less affected by humidity. It is characterized by excellent releasability from the toner fixing rubber roll, and this provides the advantage that clear images can be formed at high speeds.

The present invention will be explained in detail below.

The toner binder of the present invention is composed of the above-mentioned component (a) alone or in combination with component (b), and the silicon atom-containing copolymer resin as the component (a) has the formula H ₂ C= C(R ¹ )(Q) (R ¹ and Q in the formula
can be easily synthesized by copolymerizing the unsaturated group-containing organosilicon compound represented by (as described above) and styrene or α-methylstyrene using a radical polymerization initiator such as an organic peroxide. . The copolymerization method may be a conventionally known method such as bulk polymerization, solution polymerization, ionic polymerization, emulsion polymerization, suspension polymerization, or the like.

Examples of the unsaturated group-containing organosilicon compound used in the above copolymerization include the following. However, in the following, Me represents a methyl group.

In the above examples, R ¹ is a methyl group or a hydrogen atom, and R ² is a methyl group, but R ² may also be an alkyl group other than a methyl group, or even an aryl group such as phenyl. .

Copolymer resins obtained by copolymerizing such unsaturated group-containing organosilicon compounds with styrene or α-methylstyrene come in various structures and molecular weights depending on the copolymerization molar ratio, etc. In the present invention, it is required that 0.01<p/p+q≦0.3 in the formula described as component (a) above. If the ratio is less than 0.01, the releasability from the rubber roll is insufficient, making high-speed fixing difficult, and the rubber roll surface becomes easily dirty, which is undesirable. On the other hand, if the ratio is greater than 0.3, the copolymerization The melting point of the resin becomes low, making it impossible to satisfy the performance as a toner binder.

It is desirable that the degree of polymerization, that is, the value of p+q, of this copolymer resin satisfies the softening point (approximately 80 to 120°C) required for this resin as a binder for toner, and from this point of view, p+q is
It is said to be in the range of 100 to 2000. When this value is less than 100, the copolymer resin has a low softening point and is unsuitable for toner binders.
It is difficult to manufacture products with a higher degree of polymerization.

On the other hand, the component (b) used as required may be any of those conventionally used as binders for toners, such as thermoplastic resins with softening points in the range of 80 to 120°C, such as polystyrene resins, epoxy resins, Terpene resin, acrylic resin, styrene-acrylonitrile copolymer resin, styrene-
Examples include acrylic copolymer resins.

The allowable amount of component (B) to be blended varies depending on the specific type of component (A), but is generally up to 5 parts by weight per 1 part by weight of component (A).

Next, examples of the present invention will be given.

Example 1 In a reaction flask, the formula 41.0 g (0.1 mol) of methacryloxy group-containing organosilicon compound shown by, 94.0 g (0.9 mol) of styrene,
2.4g of benzoyl peroxide was charged, the temperature was gradually raised while stirring, and a copolymerization reaction was carried out at 100℃ for 6 hours, with a degree of polymerization of approximately 1000 and a softening point of approximately 90.
A copolymer resin was obtained.

80 parts by weight of this copolymer resin and 20 parts by weight of carbon black.
Parts by weight were blended, sufficiently kneaded in a kneader, and then ground into particles of approximately 20 μm or less in a pulverizer. Next, add carrier iron powder (approximately particle size
200 μm) were mixed to prepare a developer (toner composition).

When this developer was used to make copies using a dry photocopying machine using a magnetic brush development method, clear images without fog were obtained. Even after 50,000 copies were made, the developer had excellent releasability from the rubber roll and no scumming occurred on the copied images.

Furthermore, the above developer had excellent fluidity and did not aggregate during storage, and no deterioration of various properties was observed even after storage for 10 months.

Example 2 In a reaction flask, the formula 67.2 g (0.2 mol) of methacryloxy group-containing organosilicon compound shown by, 83.5 g (0.8 mol) of styrene,
Add 3.0g of benzoyl peroxide and heat to 100℃
A copolymerization reaction was carried out for 6 hours to obtain a copolymerized resin having a degree of polymerization of about 1200 and a softening point of 87°C.

80 parts by weight of this copolymer resin and 20 parts by weight of carbon black.
Parts by weight were blended, sufficiently kneaded in a kneader, and then ground into particles of approximately 20 μm or less in a pulverizer. Next, add carrier iron powder (approximately particle size
200 μm) was mixed to prepare a developer.

When copies were made using this developer using the same copying machine as in the previous example, clear images without fog were obtained. Even after 30,000 copies were made, the developer had excellent releasability from the rubber roll, and no scuffing occurred on the copied images.

Furthermore, the above developer had excellent fluidity and did not aggregate during storage, and no deterioration of various properties was observed even after storage for 10 months.

Example 3 In a reaction flask, the formula 102.5 (0.25 mol) of methacryloxy group-containing organosilicon compound shown by, 89.3 g of α-methylstyrene
(0.75 mol) and 5.0 g of benzoyl peroxide were charged, and a copolymerization reaction was carried out at 100°C for 6 hours to obtain a copolymerized resin having a degree of polymerization of approximately 800 and a softening point of 83 to 85°C.

30 parts by weight of this copolymer resin, 50 parts by weight of epoxy resin, and 20 parts by weight of carbon black were blended, thoroughly kneaded in a kneader, and then milled into a powder of about 20 μm.
Grinded into the following particles: Next, 100 parts by weight of carrier iron powder (particle size: about 200 μm) was mixed with 5 parts by weight of this pulverized material to prepare a developer.

When this developer was used to make copies using the same copying machine as in Example 1, clear images without fog were obtained. Even after 30,000 copies were made, the releasability of the developer from the rubber roll was excellent and no scumming occurred on the copied images.

Furthermore, the above developer had excellent fluidity and did not aggregate during storage, and no deterioration of various properties was observed even after storage for 10 months.

Comparative Example 80 parts by weight of polystyrene resin and 20 parts by weight of carbon black were sufficiently kneaded in a kneader, and then ground into particles of about 20 μm or less in a pulverizer. Add carrier iron powder (approximately 200μ particle size) to 5 parts by weight of this pulverized material.
m) 100 parts by weight were mixed to prepare a developer.

Using this developer, copies were made using the same copying machine as in Example 1. After 10,000 copies were made, scumming occurred on the printed matter, and the releasability of the developer from the rubber roll also deteriorated.

Furthermore, this developer aggregated after being stored for 10 months and became unusable.

Claims (1)

[Claims] 1 (a) The main chain is of the formula [R ¹ in the formula is a hydrogen atom or a methyl group, Q
is the expression (where R ² is a monovalent hydrocarbon group having no aliphatic unsaturated group, m is an integer of 1 to 3, n is an integer of 1 to 10, a is 0, 1 or 2), p
and q is a positive number, 100≦p±q≦2000, 0.01<p/p+q≦0.3], and (b) 1 part by weight of a silicon atom-containing copolymer resin having a softening point of 80 to 120. A binder for an electrophotographic toner, comprising 0 to 5 parts by weight of a silicon atom-free thermoplastic resin having a temperature range of 0 to 5 parts by weight.