Mitsui Toatsu Chemicals, Incorporated

Kazuo Hagiwara

Masaaki Shin

Akira Misawa

Kazuo Hisamatsu

Keiichi Ishikawa

Tetsunosuke Shiomura

Takashi Kobayashi

Tatuo Ooka

Hideo Sadotomo

The present invention provides a toner composition mainly comprising a binder resin (D) which contains at least 20% by weight of an urethane-modified polyester resin (C) obtained by reacting a polyester resin (A) with an isocyanate compound (B) and whose gel fraction ranges from 2 to 75% by weight. The toner composition exhibits good melting properties upon heating suitable for fast reproduction such as a low lower limit of the fixing temperature and a wide range for permitted fixing temperature and is further excellent in resistance to blocking, resistance to carrier contamination and image-forming properties. The binder resin as the main component of the toner composition can be prepared according to a method comprising the step of continuously adding an isocyanate compound (B) to a polyester resin (A) in an equivalent ratio, NCO/OH, of the amount of the NCO groups of the isocyanate compound (B) to that of OH groups of the polyester resin (A) ranging from 0.3 to 1.00 with kneading to react them, in a kneading means having a built-in screw.

Toner composition for electrophotography

Disclosed is a toner composition for electrophotography which comprises, as a principal component, a urethane-modified polyester resin whose loss tangent (tan .delta.) has a maximum and a minimum both falling within the range of from 0.7 to 2.5, the loss tangent being determined at 150.degree. C. and a frequency ranging from 10.sup.-2 to 10 Hz. The toner composition has excellent low temperature fixing ability and offset resistance as well as a wide range of permitted fixing temperature.

A toner composition for electrophotography comprises, as a principal component, a reaction product of a mixture which comprises 20 to 80% by weight of a polyester resin (A) whose number average molecular weight ranges from 1,000 to 5,000, whose glass transition point ranges from 0.degree. to 50.degree. C. , whose OH value ranges from 20 to 60 KOHmg/g and which is prepared by using at least one trifunctional alcohol in an amount of from 2 to 10 mole % on the basis of the total amount of starting raw alcohols consisting of at least one diol and at least one trifunctional alcohol; and 80 to 20% by weight of a polyester resin (B) whose number average molecular weight ranges from 1,000 to 5,000, whose glass transition point ranges from 50.degree. to 90.degree. C. and whose OH value is not more than 5 KOH mg/g, with a diisocyanate. The toner composition has hot-melt properties suitable for rapid copying, for instance, the lower limit of fixing temperature thereof is low and the temperature range within which the toner can be fixed is very wide. Moreover, the toner composition is excellent in resistance to offset, antiblocking properties, resistance to ADF contamination, pulverization properties and quality of images. Thus, the toner composition shows practically excellent quality as a toner composition for electrophotography.

A resin for toner of electrophotography comprises a urethane-modified polyester resin (D) having a glass transition temperature ranging from 40.degree. to 75.degree. C., which is obtained by reacting a resin mixture composed of a polyester resin (A) having a number-averaging molecular weight of 1,000 to 15,000 and a hydroxyl value of 10 to 100 and a polyester resin (B) having a number-average molecular weight ranging from 1,000 to 5,000 and a sum of acid value and hydroxyl value of less than 10, in a weight ratio of (A)/(B) ranging from 20:80 to 60:40, with 0.3 to 0.99 molar equivalent of an isocyanate compound (C) per one molar equivalent of hydroxyl group of the polyester resin (A). The resin for toner is excellent in grindability and storage stability and it provides toners for electrophotography having good anti-blocking properties and good fixing properties whereby good images free of fogging can be obtained.

Resins for toner of electrophotography and method for manufacturing the

A resin for toner of electrophotography comprises a urethane-modified polyester resin (D) having a glass transition temperature ranging from 40.degree. to 75.degree. C., which is obtained by reacting a resin mixture composed of a polyester resin (A) having a number-average molecular weight of 1,000 to 15,000 and a hydroxyl value of 10 to 100 and a polyester resin (B) having a number-average molecular weight ranging from 1,000 to 5,000 and a sum of acid value and hydroxyl value of less than 10, in a weight ratio of (A)/(B) ranging from 20:80 to 60:40, with 0.3 to 0.99 molar equivalent of an isocyanate compound (C) per one molar equivalent of hydroxyl group of the polyester resin (A). The resin for toner is excellent in grindability and storage stability and it provides toners for electrophotography having good anti-blocking properties and good fixing properties whereby good images free of fogging can be obtained.

A solution containing atactic polypropylene by-produced during the preparation of a propylene-containing polymer is passed through a tubular, elongated heating zone having a pressure difference of at least 3 kg/cm.sup.2 between its inlet and outlet so that the calculated flow velocity at the outlet is at least 40 m/sec, whereby sticky fine particles of molten atactic polypropylene substantially free of the solvent are formed in suspension in the vaporized solvent. Then, the sticky fine particles are separated from the vaporized solvent.

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Kanagawa, Japan

Kazuo Hagiwara