FR2515374A1 - DRY DEVELOPER FOR ELECTROPHOTOGRAPHY - Google Patents

Abstract

DRY DEVELOPER FOR ELECTROPHOTOGRAPHY CONSISTING OF A COLORANT AND AS BINDING RESIN A POLYMER OBTAINED BY POLYMERIZATION, IN A HOMOGENEOUS SYSTEM, FROM 0.01 TO 1.5 PARTS BY WEIGHT OF A COPOLYMERISABLE MONOMER CONTAINING A RADICAL AMINO AND B 98, 5 TO 99.99 PARTS BY WEIGHT OF A HYDROPHOBIC COPOLYMERISABLE MONOMER IN THE PRESENCE OF C AN AZONITRILE TYPE POLYMERIZATION PRIMER AT 5 C 0.5 - 1.5 LOG A (PARTS BY WEIGHT).

Description

The present invention relates to a developer

  dry for direct and indirect electrophotography.

  The electrophotographic development is generally divided into two categories. One is constituted by the regular development in which the electronic image

  latent static is made visible by electronic attraction

  The other is the inversion development in which the latent image is made visible using a toner charged with the same polarity by means of an electric field between the Magnetic brush and latent image surface In both processes, the toner image

  is formed directly or indirectly on the sheet

  The toner particles are attached to the image-receiving sheet by heating or pressing the toner particles or by contacting the toner particles with a solvent vapor to complete the development. The latent electrostatic image is formed by the photoconductive phenomenon that occurs when a sensitive body is uniformly charged and optical information is applied to the sensing body. The charge polarity may be positive or negative depending on the type of the sensing body. Polarity toner particles is therefore determined by the combination of the sensitive body and the

  development process to use.

  Generally, the toner consists of a binder resin, a colorant, and other additives, with the binder resin being the predominant part.

  coumarone-indene, a terpene resin, a styrenic resin

  rene, a styrene copolymer resin, a polyester resin and an epoxy resin Few of them are

  positively charged to a great extent by friction.

  According to the known method of positively charging the toner, a charge control agent such as a dye such as nigrosine is incorporated in the toner, or the binder is prepared by polymerization of a monomer containing a

amino radical.

  The first method has the following drawbacks. Nigrosine has poor miscibility with the binding resin which is the main constitutive component.

  This miscibility occurs when

  that the toner particles break after mixing

  lined up in the development unit When the nigrosine

  is simply dispersed in the toner, the breakdown of

  toner particles form opposite charge particles (ne-

  gative) that do not contain nigrosine These particles

  adhere to the area that is not exposed to imagery signals.

  ge, which produces what is called a veil In addition, the nigrosine dye is hydrophilic and the importance of its

  load varies according to the humidity of the environment.

  lags in deterioration of image quality In addition, the nigrosine dye usually causes

  intense and is not suitable for a colored toner.

  The second method also has certain disadvantages The monomer containing an amino radical is hydrophilic and dissolves in the aqueous phase when it is

  copolymerized with other hydrophobic monomers by poly-

  suspension merification in the aqueous system In addition,

  the monomer containing an amino radical is

  surface of water and suspended monomer particles

  The resulting resin is less charged by friction or is not uniformly loaded. This leads to images

  For the aforementioned reasons, we are looking for

  blow a toner and a toner binding resin that will

  ge positively to a great extent, is inert vis-à-vis

  environmental humidity and has superior durability.

  pool. It is an object of the invention to provide a dry developer toner for electrophotography which forms a clear, non-veiled image with a toner binding resin which is significantly positively charged. More particularly, one of the objects of the invention is provide

  a toner which lacks the aforementioned drawbacks, insensitive

  sible to the humidity of the environment and of

  and which contains the binding resin which is positively charged. In order to achieve the objects of the invention, the invention

  have conducted a series of research leading to

  cover that the binding resin which constitutes, with a co-

  lorant, a dry developer for electrophotography,

  is positively charged in a significant way when the

  binding agent is prepared by polymerization in a system

  homogeneous system of a copolymerizable monomer containing an amino radical and a copolymerizable hydrophobic monomer

  in the presence of an azone-type polymerization initiator

  The static charge due to the friction between the binding resin and the iron powder is influenced by the presence of the polymerizable monomer containing an amino radical and the determined amount of

  the azonitrile polymerization initiator

  the invention is based on these discoveries.

  The present invention therefore relates to a development

  dry cell for the main compound electrophotography

  of a binding resin and a dye, characterized

  in that said binding resin is composed mainly of

  of a polymer obtained by polymerisation, in a system

  homogeneous system, from (A) 0.01 to 1.5 parts by weight of a mono-

  copolymerizable mother containing an amino radical and (B) 98.5

  99.9 parts by weight of a copolymeric hydrophobic monomer

  risible in the presence of (C) an azonitrile type polymerization initiator in an amount of 5 (C) 0.5 1.5 x

log (A) (parts by weight).

  If the copolymerizable monomer containing a radical

  cal amino is copolymerized in an amount greater than

  5% by weight, generally the toner obtained is positively charged. However, if the amount of this monomer is reduced, the importance of the charge per unit weight of the

  However, according to the present invention,

  vention, it is possible to obtain a sufficient

  positively powerful even when the amount of monomer po-

  permeable polymer containing an amino radical is reduced to

  1.5 parts by weight, when using an initiator

  azonitrile type polymerization in a defined amount

  below for 100 parts by weight of the total monomers: (C) at 0.5 1.5 x log (A)

  (o (A) is the amount (parts by weight) of the co-monomer

  polymerizable containing an amino radical, and (C) is the amount (parts by weight) of the polymerization initiator

  azonitrile type) The binding resin obtained is char-

  positively important even when the quantity of

  copolymerizable monomer containing an amino group,

  which is a hydrophilic component, is extremely reduced.

  In addition, the bonding resin is insensitive to temperature.

  ture and moisture of the environment.

  therefore provides a dry developer for electrophotography.

  graphie that has superior durability and forms images

sharp, without veil.

  The copolymerizable monomer containing the amino radical used for the binding resin of the invention is preferably represented by the following formula: R 1

CH 2 = C R 2

0 = C X (CH 2) n N R 3

  wherein R 1 is a hydrogen atom or a radical male

  Thyle; R 2 and R 3 are a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms or an aryl radical; n is an integer of 1 to 4; and X represents -0 or -N-. H

  Examples of such monomers include

  dimethylaminoethyl methacrylate, diethyl methacrylate

  thylaminoethyl, dimethylaminoethyl acrylate and dimethylaminopropylmethacrylamide. The hydrophobic copolymerizable monomer used

  in the invention is preferably defined by a solubilization

  The amount of water in this monomer of less than 1.0% by weight and a solubility of this monomer in water of less than 1.0% by weight. Examples of such monomers include

  styrene monomers, such as styrene, vi-

  n-toluene, α-methylstyrene and dimethylstyrene; and

  monomeric esters of the (meth) acrylate type such as acrylate

  butyl endate, 2-ethylhexyl acrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate and methacrylate

lauryl.

  The azonitrile polymerization initiator should preferably be a compound in which a radical represented by the formula below is joined to at least one of the azo radicals: R

C R '

CN

  in which R and R 'represent an alkyl radical or an alkoxyalkyl radical having 1 to 4 carbon atoms

  examples of such compounds include azobisisobutyronitrile

  trile, azobisdimethylvaleronitrile, azobis (2,4-dimethyl-

  4-methoxyvaleronitrile) and 2-phenylazo (2,4-dimethyl-4-

  methoxyvaleronitrile. According to the invention, when the amount of the copolymerizable monomer containing an amino radical is decreased, the amount of the azonitrile polymerization initiator must be increased.

  the azonitrile polymerization initiator, the copolymer

  mother has an excessively low molecular weight and

  bad properties We must use less than 5

  by weight of the azo-type polymerization initiator

  nitrile per 100 parts by weight of the total monomers.

  When the monomer content containing a radi-

  Amino cal of co Dolymeric increases, the importance of the charge

  However, as the copolymer monomer

  sand is hydrophilic, the importance of the copoly-

  mother obtained is strongly influenced by the humidity of the

  environment and decreases rapidly in high humidity.

  The effect of humidity increases when the content of the mono-

  increases in order to obtain a copolymer which is insensitive to

  environment, and to ensure the importance of the required load, it is necessary for the monomer to be co-polymerized at a rate of 0.01 to 1.5% by weight relative to the total amount

monomers.

  In the invention, the polymerization process is

  an important factor and the polymerization must be carried out

  killed in a homogeneous system, that is to say by polymerisation

  mass or solution polymerization

  aqueous suspension polymerization or polymerization

  emulsion, the importance or regularity of the

  Electrical age of the resulting copolymer decreases.

  To perform the polymerization in a system

  Homogeneous, it is preferable, from an operative point of view, the poly-

  Merification in solution compared to bulk polymerization. When using the positively charged moving resin of the invention, it is possible to prepare a toner which can be stably and uniformly loaded without the use of a charge control agent.

to charge positively.

  The bonding resin prepared according to the invention

  may be mixed with another common binding resin

  toner for the extent that miscibility is not

impaired.

  The invention is illustrated by the following examples:

  in which the compositions are expressed in par-

  by weight The results of the evaluations are grouped together

In the picture.

Exem Dle 1.

  In a reactor equipped with an agitator, a

  chicken, a nitrogen inlet, a reflux condenser and a thermocouple for the measurement and regulation of the temperature, 100 parts of xylene are introduced as solvent for solvent polymerization maintained at 80 WC, we

  dropwise, under a stream of nitrogen, to

  kill the polymerization, a liquid mixture consisting of 2.5

  parts of azobisisobutyronitrile (polymerization initiator

  83.7 parts of styrene comonomer, 16.2 parts of butyl acrylate (ester) and 0.1 part of dimethylaminoethyl methacrylate (ester). The polymerization solvent and the residual monomers are distilled off.

  heating the reactor and creating a vacuum After eliminating

  The binding resin has a glass transition point (Tg) of 620 C and a softening point (PR) of

120 C.

  94 parts of this binder resin are mixed with 6 parts of carbon (Mitsubishi Kasei Carbon No. 44) by melting on a heated cylinder. After cooling, the mixture is milled with a hammer mill and then pulverized with a particle jet mill. This powder is used as a toner. 3 parts of toner are mixed with 100 parts of iron powder separated by a sieve with a mesh size of 0.105 to 0.074 mm.

  static electricity (p C / g) according to the blowing method.

  Also, 10 parts of the toner are mixed with 100 parts of the iron powder used as a support and this mixture is evaluated by forming an image with a commercial duplicator.

  which forms a negative electrostatic latent image

  and has a magnetic brush development element.

Example 2

  Using the same reactor and the same method as in Example 1, a binding resin having a Tg of 65 C and a PR of 124 C from 50 parts of

  xylene (polymerization solvent), 85.0 parts of vinyl

  toluene as comonomer, 14.5 parts of butyl acrylate (ester), 0.5 part of dimethylaminopropylmethacrylamide and

  1.5 parts of azobisdimethylvaleronitrile (initiator of poly-

  The binding resin obtained is converted into

  a toner that is evaluated in the same way as in the example

ple 1.

Example 3

  Using the same reactor and method as in Example 1, a binding resin having a Tg of 840 C and a PR of 142 C was obtained from 100 parts of xylene (polymerization solvent), 89.0. parts of styrene

  as a comonomer, 10.0 parts of 2-ethyl methacrylate

  hexyl ester, 1.0 part of dimethylamino methacrylate

  ethyl (ester) and 0.5 part of azobisdimethylvaleronitrile (polymerization initiator).

  bond obtained in a toner that is evaluated as in the e-

xample 1.

Example 4

  Using the same reactor and the same process as in Example 1, a binding resin having a Tg of 720 ° C. and a PR of 126 ° C. is obtained from 30 parts of xylene (polymerization solvent), 70.degree. 3 parts of styrene as comonomer, 29.4 parts of butyl methacrylate (ester), 0.3 part of dimethylaminoethyl methacrylate (ester) and 1.5 parts of azobisisobutyronitrile (polymerization initiator) The binding resin obtained is converted into

  to a toner that is evaluated as in Example 1.

Comparative Example 1

  Using the same reactor and the same method as in Example 1, a binding resin having a Tg of 63 ° C. and a PR of 115 ° C. is obtained from 100 parts of xylene (polymerization solvent), 80.0 g. parts of styrene comonomer, 15.0 parts of butyl acrylate (ester), 5.0 parts of dimethylaminoethyl methacrylate (ester) and

  1.0 parts of azobisisobutyronitrile (polymerization initiator)

  The resulting binding resin is converted into a

  which is evaluated as in Example 1.

Comparative Example 2

  Using the same reactor and the same method as in Example 1, a binding resin having a Tg of 66 C and a PR of 1180 C from 100.0 parts is obtained.

  xylene (polymerization solvent), 65.0 parts of

  nyltoluene as comonomer, 30.0 parts of methacrylate

  of butyl ester, 5.0 parts of diethyl methacrylate

  aminoethyl (ester) and 1.5 parts of benzoyl peroxide (polymerization initiator) The resulting binding resin is converted into a toner which is evaluated as in

Example 1

Comparative example 3.

  Using the same reactor as in Example 1, a binding resin having a Tg of 650 ° C. and a PR of 121 ° C. is obtained in the following manner: in 200 parts of deionized water containing 2 parts of polyvinyl alcohol ( Gosenol GH-20, product of Nihon Gosei) maintained between 80 and 900 C, is added dropwise in 2 hours a mixture consisting of 84 parts of styrene, 14 parts of acrylate

  butyl ester, 2 parts of dimethylamino methacrylate

  ethyl (ester) and 1 part azobisisobutyronitrile (amorphous

  After 4 hours of aging and cooling of the reaction mixture, the polymer is filtered off, washed with water and dried. The resulting binding resin is converted into a toner which

  it is evaluated as in example 1.

Reference example 1.

  Using the same reactor and method as in Example 1, a binding resin was obtained from 50 parts of xylene (polymerization solvent), 79.0 parts of styrene as comonomer, 20.9 parts of

  2-ethylhexyl methacrylate (ester), 0.1 part of dimethyl

  thylaminopropylmethacrylamide and 1.5 parts of azobisisobutyl

  ronitrile (polymerization initiator) The bonding resin obtained is converted into a toner and is evaluated as

in example 1.

Reference example 2.

  Using the same reactor and process as in Example 1, a binding resin is obtained from 100 parts of xylene (polymerization solvent), 84.0 parts of styrene as comonomer, 15.7 parts of butyl acrylate (ester), 0.3 parts of methacrylate

  dimethylaminoethyl ester and 0.8 parts of azobisdimethyl

  valeronitrile (polymerization initiator) The resulting binding resin is converted into a toner and evaluated as

in example 1.

TABLE 1

  Charge * Ex 1 + 19.8 i C / g Ex 2 + 29.4 Ex 3 + 30.1 Ex 4 + 22.1 Ex + 33.8 comp 1 Ex + 12.8 comp 2 Ex + 8.2 comp , 3 Ex of + 5.2 ref 1 Ex of + 7.1 ref 2 Remarks: * Measured according to 1 l relative humidity ** Percentage of the load midity during one hour tive. Cons Evaluation of the image of the image - $ * c:% Good image sharp Good image sharp 92 Good image sharp 93 Good image sharp 61 Variation in density due to humidity 68 Variation in density and haze due to humidity 81 Sail 94 Veil and blur of fine lines 93 Blur of fine lines

appreciable

o o o o A x x x x

  blowing method at 20 and 40% human

measured after treatment with human

at 35 C and 90% moisture relative to

  As shown in Table 1, the developer

  for electrophotography of the invention has properties

  stable and stable charge and provides a good clear image in the compositions of Reference Examples 1 and

  2, the formula> (C)> 0.5 1.5 x log (A) is not satisfactory.

  In the case of Comparative Examples 1 and 2, the importance of the charge is acceptable but its retention is low. In the case of the comparative exemule, the amount of charge is low and the quality of the image is poor.

  3, the importance and the retention of the charge are low.

Claims (4)

  1 Dry developer for electrophotography   composed mainly of a binding resin and a co-   lorant, characterized in that said binder resin is composed mainly of a polymer obtained by polymerization, in a homogeneous system, of (A) 0.01 to 1.5 parts by weight of a copolymerizable monomer containing a amino radical and (B) 98.5 to 99.99 parts by weight of a hydrophobic copolymerizable monomer in the presence of (C) an azonitrile polymerization initiator in an amount of (C)> 0.5 1.5 x log (A) (parts by weight). Dry developer for electrophotography according to claim 1, characterized in that the copolymerizable hydrophobic monomer is defined by a solubility of water in said monomer of less than 1.0% by weight and a solubility of said monomer in the lower water. at 1.0% by weight.   Dry developer for electrophotography according to claim 1, characterized in that the azonitrile polymerization initiator comprises a radical   represented by formula (1) related to at least one of the azo, R C R '(1)   CN in which R and R 'represent an alkyl radical or a   alkoxyalkyl radical having 1 to 4 carbon atoms.   Dry developer for electrophotography according to Claim 1, characterized in that the copolymerizable monomer containing an amino radical is a compound represented by the formula (2), * R 1 CH 2 = R I R-2 (2) 0 = C X (CH 2) n N R 3   in which R 1 represents a hydrogen atom or a   methyl dical; R 2 and R 3 represent a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms or an aryl radical; N is an integer of 1 to 4; and X is -O or -N-. H H