JPS617846A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To improve the shelf stability and fixability of a toner contg. polyester resin as well as the electrostatic chargeability and flowability by sticking fine particles of silical or alumina contg. carboxylic acid to the surface of the toner or by incorporating the particles into the toner. CONSTITUTION:A flowability improver such as fine particles of silica contg. carboxylic acid is stuck to the surface of a toner contg. polyester resin, or the improver is incorporated into the toner. A carboxyl group as the characteristic group of the carboxylic acid takes part in a condensation reaction with a hydroxyl group remaining in the polyester. When carboxylic acid having two or more carboxyl groups is used, the groups condese with remaining hydroxyl groups at two or more positions and cause cross-liking. The degree of polymn. is maximized at the surface of the toner, caking or other deterioration of the toner due to thermal deformation is hardly caused during storage, and high fixability can be obtd. during fixing with a heated roll.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the storage stability and fixing properties of toners for developing electrostatic images, particularly toners using polyester resins.

Although there are inventions aimed at improving chargeability and fluidity by sticking fine powder such as silica on the surface of toner, it is not possible to significantly improve storage stability and fixing properties using only fine powder such as silica. do not have.

An object of the present invention is to improve the above-mentioned drawbacks of the prior art and to provide a new toner for developing electrostatic images that has excellent storage stability and fixing properties, and particularly has excellent charging properties when applied to negatively charged toners. shall be.

The special purpose of the present invention is to add a fluidity improver such as fine particle silica containing carboxylic acids to the surface or inside of a toner using a polyester resin. Carboxylic acids have a calpho'P-syl group as a characteristic group,
This group causes a condensation reaction with the hydroxyl groups remaining in the polyester. When a carboxylic acid containing two or more carboxyl groups is used, the polyester resin is bridged via the carboxylic acid at the two hydroxyl groups in the polyester resin in order to condense with the two remaining hydroxyl groups.

This increases the degree of polymerization of the surface of the toner. Therefore, toner deterioration such as caking caused by heat deformation of the toner during storage is less likely to occur, and when this toner is fixed with a hot roll, it exhibits good fixing properties.

When a magnetic toner is desired, magnetic powder may be contained in the resin.

Examples of the present invention will be described below.

Example 1 Polyester resin (Kajo Soap KTR=215
0) and 10 wt% of furnace carbon black (Mitsubishi Kasei, $44) were thoroughly mixed in a ball mill and then kneaded with a hot roll.

The kneaded material was allowed to cool naturally, and then coarsely ground in a cuckoo mill, ground in a fine grinder using a Genl [Nagare], and further classified in an air classifier to obtain a fine powder with a particle size of 5 to 20 μm. the below described(
A toluene solution of trimesic acid (5
Weight basis) ) 100ml 1'f colloidal silica (Nippon Aerosil I (,972) 50ItK adsorbed and further dried powder was placed in a Hensel mixer equipped with a rotating mechanism, 10 minutes of the fine powder toner was added and mixed by rotation. , this is referred to as toner (1).

(I) ([1 bias) Comparative Example 1 Instead of the trimesic acid-containing colloidal silica added to the toner prepared in Example 1, only 50 f of colloidal silica (Nippon Aerosil R972) was added to the surface of the fine powder toner obtained in Example 1. was added in the same manner as in Example 1, and this was used as toner (2).

The storage stability of each of the above toners +II and f21 was investigated. For storage stability, toner 5f was placed in a petri dish in a soil environment of 50'C and 40% RI, and the degree of aggregation of the toner was examined after leaving it for 48 hours.

As a result, toner (2) adhered between toner particles and became a solid substance, but toner (1) was in a fluid state.

According to the present invention, good storage and fixing properties, which could not be achieved with conventional polyester thread toners, can be achieved by simply adding a fine powder fluidity improver such as silica containing carboxylic acid to the toner surface. There is an effect that can be achieved with.

Claims (1)

[Claims] 1. A toner for developing an electrostatic image, characterized in that a toner using a polyester resin has fine particle silica or fine particle alumina containing carboxylic acids added to the surface or inside thereof.