Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Process of making developer composition
Reexamination Certificate
1998-05-12
2001-02-20
Dote, Janis L. (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Process of making developer composition
C430S109500, C430S110100
Reexamination Certificate
active
06190819
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic image-developing toner which is used for an electronograph and the like.
A developer to be used for an electronograph and the like is once adhered onto an image carrier, for example, such as a photosensitive material on which electrostatic images are formed, then transferred from the photosensitive material onto a paper in the transfer step, and then fixed onto a copy paper in the fixing step. In this case, as developers for developing electrostatic images formed on the latent image carrying surface, there have been known a dual-component developer comprising a carrier and a toner and a monocomponent developer requiring no carrier.
By the way, charging property is one of important properties required for the toner, and the formation of positive or negative charge having a proper level and the general stability of the charge level in the lapse of time are required even under its continuous use or under an adverse condition.
Previously, toners have been made in general by melting a binder resin and additives such as a charge-controlling agent with heat, admixing, pulverizing after cooling, and classifying. They have been also made by mixing a monomer and additives such as a charge-controlling agent and polymerizing the same.
However, toners produced by such methods show bad dispersibility of a charge-controlling agent, less charge stability and unstable print density when printed under an adverse condition during their continuous use. Also, to be present the charge-controlling agent on the surface of toner, which governs the charging property, it has been necessary to add a large amount of charge-controlling agent.
SUMMARY OF THE INVENTION
In view of the above, an object of the present invention is to provide a toner having high quality, which is excellent in charge stability even in a small amount of charge-controlling agent added, and provides a proper and stable print density when printed even under a continuous use or under an adverse condition.
Accordingly, the present inventors have made an intensive study, and found as a result of which that these problems may be solved by containing a charge-controlling agent only on the surface of the toner. Thus, the present invention has been accomplished.
Namely, the present invention provides an electrostatic image-developing toner comprising at least core particles and fine particles being present on the surface of the core particles and having a mean particle size of 0.01-1 &mgr;m, the fine particles being a polymer of monomer and containing a charge-controlling agent which is soluble in the monomer before the polymerization.
The present invention also provides an electrostatic image-developing toner in which the charge-controlling agent is a compound represented by general formula (1) or a quaternary ammonium compound:
A—(X—B)
n
(1)
wherein A represents an aromatic ring residue which may have a substituent, B represents an aromatic ring residue or an aliphatic residue which may have a substituent, or a hydrogen atom, X represents —CONH—, —NHCO— or —NHCONH—, and n is a natural number of one or more.
PREFERRED EMBODIMENTS OF THE INVENTION
The present invention will be illustrated in detail hereinafter.
As monomers of vinyl series to be used in the present invention, there are exemplified monomers of vinylaromatic series, monomers of (meth)acrylic ester series, (meth)acrylic acid monomers, monomers of vinylether series, and the like. Specific examples include, for example, monomers of vinyl aromatic series, such as styrene, &agr;-methyl styrene, vinyl toluene, &agr;-chlorostyrene, o-, m- and p-chlorostyrene, p-ethyl styrene, divinyl benzene; monomers of (meth)acrylic ester series, such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, ethyleneglycol dimethacrylate, tetraethyleneglycol dimethacrylate; (meth)acrylic acid monomers such as acrylic acid, and methacrylic acid; monomers of vinyl ether series, such as vinyl-n-butyl ether, vinylphenyl ether, and vinylcyclohexyl ether.
These monomers may be used alone or two or more of them may be copolymerized.
Preferably, among these monomers, those of vinyl aromatic series or (meth)acrylic ester series may be used.
As charge-controlling agent to be dissolved in these monomers of vinyl series, there are exemplified those which may dissolve in an amount of more than 0.5 wt % at a temperature of polymerization in the vinyl monomer and in particular, preferably those which may dissolve in amount of more than 0.5 wt % at 20° C. More preferably, there are exemplified those which may dissolve in an amount of more than 2 wt % at 20° C.
The charge-controlling agent added to a vinyl monomer is preferably dissolved wholly at the polymerization to obtain uniform fine particles.
So long as the above-mentioned conditions are satisfied, the chemical structure of charge-controlling agent is not particularly limited but compounds represented by general formula (1) or quaternary ammonium compounds are particularly preferred.
In general formula (1), A represents an aromatic ring residue, which may have a substituent on the ring and may be a heterocyclic ring. Examples of A include aromatic ring residues having 4-30 carbon atoms and preferably, for example, a benzene ring residue, a naphthalene ring residue, an anthracene ring residue, a carbazole ring residue and the like. Particularly, a benzene and naphthalene ring residue are preferred.
B represents an aromatic ring residue which may have a substituent, an aliphatic residue which may have a substituent, or a hydrogen atom. The aromatic ring residue is the same as in A.
Further, as aliphatic residues, there are exemplified an alkyl radical (preferably C
1
-C
25
), an alkenyl radical(preferably C
2
-C
22
),an alkynyl radical (preferably C
2
-C
22
),an aliphatic ring residue which may have an atom other than carbon atom(preferably 3-7 members)and the like; For example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, tert-butyl, n-pentyl, i-pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, heptadecyl, behenyl, vinyl, allyl, propalgyl, cyclopentyl, cyclohexyl, pyrrolidine ring residue, piperidine ring residue, dioxane ring residue, morpholine ring residue and the like. The above-described aromatic ring and aliphatic residue in A and B may further have a substituent such as, for example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, tert-butyl; cyclohexyl; haloalkyl (fluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl, bromomethyl, fluoroethyl, fluoropropyl, fluorobutyl, and the like); an alkyl (preferably 1-6 carbon atoms) which may be substituted, such as hydroxyalkyl (hydroxymethyl, dihydroxymethyl, trihydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl and the like) with the proviso that the substitution to the alkyl is excluded; an alkenyl; amino, which may be substituted, such as amino, alkylamino, and dialkylamino (preferably 0-10 carbon atoms); alkoxyl (preferably 1-12 carbon atoms) such as methoxyl, ethoxyl, n-propoxyl, i-propoxyl, n-butoxyl, i-butoxyl, and tert-butoxyl; hydroxyl; a halogen atom such as hydroxyl, fluorine atom, chlorine, and bromine atom; nitro, cyano, acetyl, carboxyl, carboxymethyl, carboxyphenyl, phenyl, C
1
-C
6
alkyl substituted phenyl, and the like.
X represents —CONH—, —NHCONH— or —NHCONH— and n is a natural number of one or more, preferably 1-3.
It is well known to use as a charge-controlling agent a certain kind of compounds of quaternary ammonium series (U.S. Pat. No. 3,893,935). The compounds of quaternary ammonium series include those containing a cationic component in which nitrogen atom is substituted with an alkyl or aralkyl radical. Specific examples of substituents include preferably methyl, ethyl, ptopyl, butyl, pentyl, hexyl, he
Ando Osamu
Takahashi Noriaki
Dote Janis L.
Mitsubishi Chemical Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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