JPH0498264A - Production of resin for toner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing toner resin used for developing electrostatic images in electrophotography, etc., and in particular, relates to a method for producing a toner resin used in a dry developing method. The present invention relates to a method for producing a resin for toner.

[Conventional technology]

BACKGROUND ART A dry developing method is often used as a method for developing electrostatic images in electrophotography and the like. In the dry development method, a triboelectrically charged fine powder developer is used, and this fine powder developer, ie, toner, is composed of a resin in which conductive particles such as carbon black are dispersed.

Usually, toner charged by friction is attached to an electrostatic latent image on a photoreceptor by electrical attraction to form a toner image.

Next, this toner image is transferred onto a sheet of paper, and further, the transferred toner image is fixed onto the sheet of paper by a heating roller that has a releasability to the toner.

Toner is required to have various properties such as offset resistance (toner does not adhere to the heating roller), fixing property (toner firmly adheres to paper), and blocking resistance (toner particles do not aggregate). be done. Further, in particular, it is required that the above-mentioned offset resistance is excellent over a wide fixing temperature range.

Conventionally, as this type of toner resin, a resin made of a copolymer having a styrene monomer and a (meth)acrylic acid ester monomer as constituent units has been widely used. It has also been proposed to use modified resins by introducing carboxyl groups into such copolymers, reacting them with polyvalent metal compounds, and crosslinking the copolymers with metal ions. (For example, see JP-A-57-178250 and JP-A-61-110155).

Furthermore, in order to obtain a toner that can be used in a wide fixing temperature range, the molecular weight distribution of the toner resin composition has multiple maximum values over a wide molecular weight range, and the weight average molecular weight/number average molecular weight value It has also been proposed to increase the
JP-A-56-16144 and JP-A-56-158
(See Publication No. 340).

In order to have multiple maximum values in a wide molecular weight range or to increase the weight average molecular weight/number average molecular weight,
In the prior art described above, resin for toner was manufactured by the following method. That is, (a) a method of mixing a low molecular weight polymer component and a high molecular weight polymer component; or (b) a method of mixing a low molecular weight polymer component and a high molecular weight polymer component;
) producing a polymer constituting either the low molecular weight polymer component or the high molecular weight polymer component, and dissolving the polymer in a monomer to provide the polymer constituting the other component; This is a method of performing two-stage polymerization, etc.

[Problems to be Solved by the Invention] However, in the method (a) of mixing a low molecular weight polymer component and a high molecular weight polymer component, the polymerization steps must be carried out separately, and the method (b) requires separate polymerization steps. In the two-stage polymerization method, the polymerization process must be carried out in two stages.
In either case, there was a problem that the manufacturing process was complicated.

Therefore, an object of the present invention is to provide a novel method for producing a toner resin that can easily produce a toner resin that exhibits excellent offset resistance over a wide fixing temperature range.

[Means for Solving the Problems] The method for producing a toner resin of the present invention includes a method for producing a toner resin by combining a styrene monomer, a (meth)acrylic acid ester monomer, and a vinyl monomer having an acid group. A step of preparing a polymer cross-linked through a metal, obtained by reacting at least a copolymer serving as a structural unit with a polyvalent metal compound, and heating the polymer cross-linked through the metal. It is characterized by comprising a process.

Hereinafter, each configuration of the present invention will be explained in detail.

Styrenic monomer In the present invention, a styrene monomer can be used as a structural unit of the copolymer to be reacted with the polyvalent metal compound. Examples of styrenic monomers used include styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, P-ethylstyrene,
2.4-dimethylstyrene, p-n-butylstyrene,
p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p- -chlorostyrene, 34-dichlorostyrene, and the like. Among these, styrene is particularly preferably used.

(meth)acrylic acid ester can also be used as a constituent unit of copolymers (meth)
Examples of acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylate.
Propyl acrylate, n-butyl (meth)acrylate,
(meth)acrylic acid isobutyl, (meth)acrylic acid n
-octyl, dodecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, dimethylamineethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, or Examples include methyl α-chloroacrylate. Among these, methyl methacrylate,
n-butyl (meth)acrylate and 2-ethylhexyl acrylate are particularly preferably used.

In addition, in this specification, the expression (meth)acrylic is
The term is used to include both methacrylic and acrylic.

The acid group in the vinyl monomer having an acid group used as a constituent unit of the vinyl monomer copolymer having an acid group includes carboxylic acid, sulfonic acid, sulfinic acid, phosphonic acid, boric acid, etc. One or more types of constituting groups may be mentioned, and carboxyl groups are particularly preferably used in view of acid strength and ease of copolymerization.

Examples of vinyl monomers having carboxyl groups include:
Examples include (meth)acrylic acid, α-ethyl acrylic acid, crotonic acid, isocrotonic acid, β-methylcrotonic acid, fumaric acid, maleic acid, itaconic acid, and half-ester compounds represented by the following general formula.

(However, in the formula, L represents a divalent bonding group having 3 or more carbon atoms and having an ester bond in the molecular chain, and R' represents a hydrogen atom or a methyl group).

The half-ester compound is obtained by an esterification reaction between a (meth)acrylic acid derivative having a hydroxyl group and an aliphatic dicarboxylic acid such as succinic acid, malonic acid or glutaric acid, or an aromatic dicarboxylic acid such as phthalic acid.

Note that the dicarboxylic acid may have a hydrogen atom substituted with a halogen atom, a lower alkyl group, an alkoxy group, or the like, or may be an acid anhydride.

Examples of the above-mentioned half-ester compounds include succinic acid mono(meth)acryloyloxyethyl)L<ester,
Examples include mono(meth)acryloyloxypropyl succinate, mono(meth)acryloyloxyethyl glucuric acid, mono(meth)acryloyloxyethyl phthalate, and mono(meth)acryloyloxypropyl phthalate.

Step of obtaining a copolymer The copolymer of the above-mentioned styrene monomer, (meth)acrylic acid ester monomer, and vinyl monomer having an acid group can be produced by solution polymerization, suspension polymerization, It can be obtained by conventionally known polymerization methods such as emulsion polymerization and bulk polymerization.

In the present invention, the content of the styrene monomer component in the copolymer is 40 to 95% by weight, and the content of the acrylic ester monomer component is 40 to 95% by weight. 4-40% heavy view
The content of vinyl monomers having heavy groups is 0. 5-3
It is preferable to set it in the range of 0% by weight.

The reason why the content of the styrene monomer component is limited to 40 to 95% by weight is that if it is less than 40% by weight, the crushability of the toner will deteriorate, and if it exceeds 95% by weight, the fixing properties of the toner will deteriorate. This is because it worsens.

Further, the content of the (meth)acrylic acid ester monomer component is limited to 4 to 40% by weight because if it is less than 4% by weight, the fixing properties of the toner may deteriorate.

The content of vinyl monomer components having acid groups is O85~3
The reason for setting it in the range of 0% by weight is that if it is less than 0.5% by weight, the reaction with the polyvalent metal compound will be insufficient, and the effect of improving the offset resistance of the toner will not be expressed.
On the other hand, if the content is more than 30% by weight, the environmental resistance of the toner deteriorates, for example, the charging stability and blocking resistance under high temperature and high humidity conditions are deteriorated.

Note that the above copolymer contains a styrene monomer and (meth)
Since the copolymer contains at least an acrylic acid ester monomer and a vinyl monomer having an acid group as a constituent unit, the copolymer does not contain any other components that do not inhibit the effects described below of the present invention. You can leave it there.

The metals contained in the polyvalent metal compound reacted with the above copolymer include Cu, AgXBe, Mg, Ca, S
r, Ba, Zn, , CdXAj2, Ti, Ge, , Sn
, V, Cr, Mo, Mn, , Fe, , C01Ni and the like. In particular, among these metals, alkaline earth metals and zinc group metals are preferred, and among these, Mg and Z
n is particularly preferred.

Examples of polyvalent metal compounds include fluorides, chlorides, chlorates, bromides, iodides, oxides, hydroxides, and
sulfides, sulfites, sulfates, selenides, tellurides,
Examples include lower alkyl metal compounds such as nitrides, nitrates, phosphides, phosphinates, phosphates, carbonates, orthosilicates, acetates, oxalates, and methylated or ethylated compounds.

Among these, acetates and oxides are particularly preferred.

The amount of the polyvalent metal compound added is preferably in the range of 0.05 to 1 mole per mole of the acid group-containing vinyl monomer component. If the amount is less than 0.05 mole, the reaction with the vinyl monomer component having an acid group will be insufficient, and the effect of improving the offset resistance of the toner may not be exhibited. On the other hand, if the amount is more than 1 mole, the fixing properties of the toner may deteriorate.

To react the polyvalent metal compound with the above-mentioned copolymer,
Preferably, after solution polymerizing the copolymer, if necessary, a polyvalent metal compound dispersed in an organic solvent is introduced into the polymerization system, and the reaction is carried out by heating to an appropriate temperature, for example, 100 to 200°C. let Thereafter, the solvent is distilled off to produce a resin.

In some cases, the polyvalent metal compound may be dispersed in the polymerization system together with an organic solvent before starting the polymerization reaction to obtain the copolymer.

Furthermore, after solution polymerizing the copolymer, a polyvalent metal compound is mixed with the copolymer obtained by distilling off the solvent, and the mixture is heated at 100 to 200°C using a roll mill, kneader, extruder, etc.
The resin may be produced by melt-kneading at a temperature of .

■ A polymer cross-linked via a metal (hereinafter referred to as resin (A)) can be obtained as described above, but if the heating time described above is extended during or after the polymerization heating reaction. However, no difference was observed in the measurement of flow softening temperature, glass transition temperature, and molecular weight distribution by gel permeation chromatography (GPC) compared to the resin obtained when the heating time was not extended. Ta.

In the present invention, the resin (A) obtained as described above is
It is characterized by implementing a step of heating again. This heating can be carried out by (1) dissolving the obtained resin (A) in a solvent again, heating it at an appropriate temperature, and then distilling off the solvent, or (2) dissolving the obtained resin (A) in a roll mill. The resin (B) is obtained by melt-kneading at an appropriate temperature using a kneader, an extruder, or the like. The heating temperature in this heating step is 100~
It is necessary to carry out at a temperature in the range of 200°C.

-B It has been confirmed that the resin (B) obtained as described above has an increased molecular weight and/or melt viscosity compared to the resin (A) before reheating. Ta. That is, in the molecular weight distribution, molecules N10o,ooo~2,000,0
It was confirmed that a peak having a new maximum value appeared within the molecular weight range of 0.00, or that the ratio of existing peaks within the above molecular weight range became higher than before reheating. Also, weight average molecular weight/number average molecule! (Mw /
In some cases, the value of M n ) became large. moreover,
It was also confirmed that the melt viscosity was increased by increasing the flow softening point.

Therefore, by performing the above reheating step, the resin composition explained in the prior art section, that is, the molecular weight distribution can have multiple maximum values in a wide molecular weight range, or the values of weight average molecular weight / number average molecular weight can be changed. It can be seen that a larger toner resin can be obtained. Therefore, according to the present invention, the toner resin as described above can be produced without carrying out a complicated production method such as mixing a low molecular weight polymer component and a high molecular weight polymer component or carrying out two-stage polymerization. can get.

Note that the glass transition temperature of the resin (B) is preferably 40°C or higher. This is because if the temperature is lower than 40°C, the blocking resistance and fluidity of the toner will deteriorate.

[Effect]

In the present invention, a polymer crosslinked with a polyvalent metal compound has at least a styrene monomer, a (meth)acrylic acid ester monomer, and a vinyl monomer having an acid group as constituent units. By heating the polymer again, the molecular weight and/or melt viscosity is increased by the reheating step, and the molecular weight distribution has a plurality of local maxima in a wide molecular weight range, and the molecular weight is increased. A toner resin composition having a large value of average molecular weight/number average molecular weight can be obtained.

As mentioned above, the reason why the molecular weight and/or melt viscosity of the resin is increased by carrying out the heating process after obtaining the polymer is because the acid group moieties and polyvalent metal ions in the resin before reheating are is ionic crosslinked, and this changes to ionic crosslinking between the intermolecular acid group moiety and the polyvalent metal ion by heating, or when the acid group in the copolymer and the metal in the metal compound are polymerized in one step. This is thought to be due to insufficient ionic crosslinking, and upon heating again, ionic crosslinking between the excess metal and unreacted acid groups progresses.

[Explanation of Examples] Examples and comparative examples of the present invention will be described below.

Example 1 A mixture of 85 parts by weight of styrene, 10 parts by weight of n-butyl acrylate, 5 parts by weight of methacryloyloxyethyl succinate, and 3 parts by weight of benzoyl peroxide as a polymerization initiator was refluxed in 50 parts by weight of toluene. Below, 2.
Solution polymerization was carried out by dropping the solution over a period of 5 hours. After completion of the dropwise addition, 0.5 parts by weight of zinc oxide powder was further added while stirring under reflux of toluene, and then aged for 1 hour.

Next, while gradually raising the temperature of the system to 180°C, toluene was removed under reduced pressure to obtain resin (A-1). The weight average molecular weight (Mw) of the obtained resin was 36B20, the number average molecular weight (Mn) was 8040, and Mw/Mn=4.
58, and the flow softening point was 121°C.

100 parts by weight of this resin (A-1) was stirred in 100 parts by weight of toluene under reflux for 2 hours, and then the temperature of the thread was lowered to 1
While gradually raising the temperature to 80°C, toluene was removed under reduced pressure to obtain a resin (B-1).

Resin (B-1) had Mw of 70333, Mn of 9834, My/M71=7.15, and flow softening point of 129°C.

Example 2 65 parts by weight of styrene, 15 parts by weight of methyl methacrylate,
A mixture of 17 parts by weight of n-butyl acrylate, 3 parts by weight of methacryloyloxyethyl succinate, and 5 parts by weight of hendiyl peroxide as a polymerization initiator was mixed with toluene in which 1.8 parts by weight of magnesium acetate powder was dispersed. Solution polymerization was carried out under reflux in 50 parts by weight while dropping the solution over 2.5 hours. After the dropwise addition was completed, the mixture was aged for 1 hour while stirring under reflux of toluene.

Then, while gradually increasing the temperature of the system to 180°C,
Toluene was removed under reduced pressure to obtain resin (A2).

The Mw of the obtained resin (A-2) is 12430, and the Mn is 5.
170, Mw/Mn-2.40, and flow softening point was 111°C.

100 parts by weight of this resin (A-2) was stirred in 100 parts by weight of toluene under reflux for 2 hours, and then the toluene was removed under reduced pressure while gradually increasing the temperature of the system to 180"C. (B-2) was obtained.

Mw of this resin (B=2) is 132480, Mn is 10
350, Mw/Mn-12.8, and flow softening point was 134°C. In GPC, 500
．． A new maximum value appeared near 000.

Disaster Kaikai 1 60 parts by weight of styrene, 15 parts by weight of methyl methacrylate,
A mixture of 15 parts by weight of n-butyl methacrylate, 10 parts by weight of acrylic acid, and 7 parts by weight of benzoyl peroxide as a polymerization initiator was added dropwise to 50 parts by weight of toluene under reflux over 2.5 hours. Solution polymerization was carried out while After the dropwise addition was completed, 0.6 parts by weight of magnesium oxide powder was added thereto, and the mixture was further aged for 1 hour with stirring under reflux of toluene.

Then, while gradually increasing the temperature of the system to 180°C,
Toluene was removed under reduced pressure to obtain resin (A3).

The Mw of the obtained resin (A-3) was 7210. Mn is 37
50, Mw/Mn=1.92, and the flow softening point is 1
It was 18°C.

Roll kneading was carried out at 0°C for 10 minutes to obtain resin (B-3).

In Kono resin (B-3), Mw is 54300 and Mn is 4.
120, Mw/Mn=13.2, and the flow softening point was 126°C.

A mixture of 85 parts by weight of Hokkaido styrene, 10 parts by weight of n-butyl acrylate, 5 parts by weight of methacryloyloxyethyl succinate, and 3 parts by weight of benzoyl peroxide as a polymerization initiator was dissolved in 50 parts by weight of toluene. Solution polymerization was carried out by dropwise addition under reflux for 2.5 hours. After the dropwise addition, 0.5 parts by weight of zinc oxide powder was added while stirring under refluxing toluene, and then 3 parts by weight of zinc oxide powder was added.
Time aged.

Thereafter, while the temperature of the reaction system was gradually raised to 180°C, toluene was removed under reduced pressure to obtain resin A'l.

In the resin (A'-1) obtained as above, Mw
kyo is 37750, Mn is 10510, and Mw/Mn=
3.6, and the flow softening point was 122°C.

(A-1), (A2), (A
, -3), (B-1), (B-2) and (A'-1) and 5 parts by weight of carbon black (Diablack SH, manufactured by Mitsubishi Chemical Industries, Ltd.) at 170 parts by weight. "C
Roll kneading was carried out for 1 minute (this treatment was omitted for the resin B-3 since it already contained carbon black). Next, each resin was finely pulverized using a jet mill to have an average particle size of 13 to 15 μm, and 0.5 parts by weight of hydrophobic silica fine powder was mixed therein to produce toner from each resin.

10g of the obtained toner is 100mI! The particles were placed in a beaker and left in a constant temperature bath at a temperature of 60° C. for 24 hours, and the blocking resistance was evaluated based on the presence or absence of particle coalescence.

Further, 4 parts by weight of the above toner was mixed with 96 parts by weight of iron powder carrier having an average particle size of 50 to 80 μm to prepare a fine powder developer. The prepared fine powder developer was installed in a modified electrophotographic copying machine (U-B+x2500, manufactured by Konica Corporation), and the fixing temperature range was measured.

The fixing temperature range was evaluated by changing the temperature setting of the heating roller for fixing, examining the setting temperature at which good fixing could be achieved without causing offset, and using the set temperature.

The above evaluation results are shown in Table 1 below.

〔Effect of the invention〕

As described above, according to the present invention, a styrenic monomer,
A fairly simple process of reheating a polymer that has at least a (meth)acrylic acid ester monomer and a vinyl monomer having an acid group as structural units and is crosslinked via a polyvalent metal compound. This makes it possible to produce toner particles with a wide fixing temperature range and excellent blocking resistance.

Claims (1)

[Claims] (1) A polyvalent metal compound is reacted with a copolymer whose constituent units are at least a styrene monomer, a (meth)acrylic acid ester monomer, and a vinyl monomer having an acid group. 1. A method for producing a toner resin, the method comprising: preparing a polymer crosslinked through a metal, obtained by heating the polymer crosslinked through a metal; and heating the polymer crosslinked through a metal.