JPH0774911B2 - Capsule toner for heat roller fixing - Google Patents

Description

TECHNICAL FIELD The present invention relates to a capsule toner used for developing an electrostatic latent image formed in electrophotography, electrostatic printing, electrostatic recording, and the like. The present invention relates to a heat roller fixing capsule toner.

[Background of the Invention]

For example, in electrophotography, an electrostatic latent image is usually formed on a latent electrostatic image bearing member made of a photoconductive photoconductor by charging and exposure, and then this electrostatic latent image is formed by toner, which is a colored particle. After development, the obtained toner image is transferred to an image support such as transfer paper and then fixed by heat or pressure to form a visible image.

As a method for fixing a toner image, conventionally, a method of heating and melting the toner in a non-contact state with a heater to fix the toner,
Known methods include a method in which toner is dissolved and fixed by an organic solvent, a method in which toner is pressed and fixed, and a so-called heat roller fixing method in which a heat roller is brought into direct contact with the toner to melt and pressure-fix it The heat roller fixing method is widely used because it has high thermal efficiency and enables high-speed fixing.

However, in the latest, (a) to suppress overheating deterioration of the copying machine, and (b) to shorten the warm-up time required to raise the temperature of the heat roller to a fixable temperature after operating the heat roller fixing device. (C) To reduce the temperature drop of the heat roller due to the absorption of heat by the image support such as transfer paper to enable the stable formation of images a number of times in succession. (D) Copy From the viewpoint of downsizing of the machine and improvement of safety, it is strongly required to reduce the power consumption of the heater incorporated in the fixing device to enable the fixing process with the temperature of the heat roller kept lower. There is.

Therefore, the toner is required to (1) be able to achieve good fixing at a lower temperature, that is, to have an excellent low-temperature fixing property, and basically, the following conditions are required. is necessary.

(2) In the heat roller fixing method which is preferable as the fixing method, a part of the toner forming the image is transferred to the surface of the heat roller during the offset development, that is, the fixing, and the toner is retransferred to the next transfer paper. Since the phenomenon of smearing an image is likely to occur, it is necessary to impart the toner with a property that does not easily transfer to a heat roller, that is, offset resistance.

(3) It can exist stably as a powder without aggregation under the conditions of use or storage environment, that is, it has excellent blocking resistance.

(4) It has good triboelectrification properties, and the development process, transfer process, and cleaning process are performed well, and a clear image free from fog is obtained.

(5) The occurrence of a so-called filming phenomenon in which a toner substance adheres to the surface of the photoconductor or the surface of carrier particles is suppressed, and an image can be stably formed many times.

In the past, therefore, a technique for achieving low-temperature fixability has been proposed by using a capsule toner composed of core particles and an outer shell provided so as to cover the surfaces of the core particles as the toner. Has been done. This type of capsule toner uses a low melting point compound or a material having a low glass transition point as the core particle in order to improve the meltability at low temperature. Specifically, the following technologies are disclosed.

Technology for forming core material particles with wax (Japanese Patent Publication No. 49-
(See Japanese Patent No. 1588).

A technique in which core particles are composed of polyester crosslinked with a polyvalent metal compound (see Japanese Patent Application Laid-Open No. 58-174957).

A technique in which core particles are made of low-melting point polyester (see JP-A-58-176642).

A technique in which the core material particles are composed of a low molecular weight styrene-acrylic resin having a gel content of 20 to 70% (see Japanese Patent Laid-Open No. 58-176643).

A technique in which core particles are made of amorphous polyester having a glass transition point of 60 ° C. or lower (see JP-A-58-205161).

A technique in which core particles are composed of a crosslinked vinyl copolymer having a glass transition temperature of 55 ° C. or lower and a gel content of 20% or higher (see JP-A-58-205161).

Glass transition of core material particles is below 60 ℃ and acid value is 10 ~
Technology of 150 amorphous polyesters
8-205163).

A technique in which the core particles are composed of an amorphous polyester and a polyvalent metal compound (see JP-A-58-205164).

[Problems to be solved by the invention]

However, in the above technique, when the heat roller fixing method is applied as the fixing method, the offset resistance is considerably poor and the practicality is extremely low.

In addition, in the above techniques, under normal conditions of normal temperature and pressure (for example, temperature 20 ℃, relative humidity 60%),
Although the performance is improved compared to the above technology, the offset resistance is still insufficient, so that there is a problem that the fixing temperature range in which fixing is possible without the occurrence of the offset phenomenon is narrow, and it is still in practical use. It has low sex.

Moreover, under low temperature and low humidity conditions (for example, temperature 10 ° C, relative humidity 40%), the temperature of the image support such as transfer paper is low, so that the toner tends to be insufficiently melted during fixing. Poorly fixed toner adheres to and accumulates on the rollers that make up the fixing device and contaminates the rollers, which causes problems such as paper jams and poor conveyance, and shortens the service life of the rollers. is there.

As described above, it is the actual situation that, depending on the capsule toner of the technology, a sufficiently satisfactory capsule toner for fixing the heat roller has not been obtained yet.

This is because the conventional capsule toner is basically applied to the pressure fixing method. That is, the toner is formed so as to be suitable for the fixing method to which the toner is applied. For example, when a toner designed to be applied to the pressure fixing method is applied to the heat roller fixing method, a problem such as an offset phenomenon occurs. The dots occur, and it is not always possible to form a sufficient copy image.

[Object of the Invention]

The present invention has been made based on the above circumstances, and an object thereof is to have excellent low-temperature fixability and offset resistance, a wide practical fixable temperature range, and low-temperature low-humidity environmental conditions. Excellent low-temperature fixability is not impaired even underneath, fixing is possible without contamination of the rollers that make up the fixing device, and both blocking resistance, triboelectrification resistance, and filming resistance are excellent. It is an object of the present invention to provide a heat roller fixing capsule toner capable of stably forming a clear image without fog a number of times.

[Means for solving problems]

The heat roller fixing capsule toner of the present invention is a heat roller fixing capsule toner comprising a fusible core particle and an outer shell made of a thermoplastic resin provided so as to cover the surface of the core particle. The fusible core particles are obtained by reacting a polyvalent metal compound with the carboxy group of a vinyl polymer having a carboxy group, and the glass transition point Tg is 40 to
A core material resin of 70 ° C. is contained, and the core material resin has a molecular weight distribution of at least two groups of a low molecular weight component and a high molecular weight component, and the molecular weight distribution is determined by gel permeation chromatography. In the distribution curve, the maximum value of the low molecular weight component is in the range of 1 × 10 ³ to 2 × 10 ⁴ , and the maximum value of the high molecular weight component is in the range of 1 × 10 ⁵ to 2 × 10 ^6. Is characterized by.

[Advantageous effects of the invention]

According to the heat roller fixing capsule toner of the present invention, the core material particles have a specific glass transition point Tg obtained by reacting a polyvalent metal compound with the carboxy group of the vinyl polymer having a carboxy group. And a core resin having a specific molecular weight distribution is contained, and this core resin has a structure crosslinked by a polyvalent metal compound by so-called ionic bonds. Even if the transition point Tg is low, the viscoelasticity of the toner when melted will be of an appropriate size, and transfer of the toner substance to the heat roller of the heat roller fixing device is unlikely to occur, and excellent offset resistance can be obtained. This crosslinked structure has a weaker bond than a normal covalent bond, and therefore, even if it has a glass transition point Tg similar to that of a resin having a covalently crosslinked structure, it becomes possible to fix at a lower temperature. Particularly excellent low-temperature fixability under environmental conditions of low temperature and low humidity can be exhibited. As described above, the toner can be fixed at a low temperature without the occurrence of the offset phenomenon, so that the feasible temperature range is sufficiently widened, and a very excellent practical toner can be obtained.

Further, since the core material particles are covered with the outer shell made of the thermoplastic resin, the outer shell provides excellent blocking resistance, good triboelectrification property, cleaning property, and excellent filming resistance. .

[Specific configuration of the invention]

 The specific configuration of the present invention will be described below.

In the present invention, basically, a core material resin obtained by reacting a polyvalent metal compound with the carboxy group of a vinyl polymer having a carboxyl group (hereinafter, also referred to as “specific core material resin”). The surface of the contained core particles is covered with an outer shell made of a thermoplastic resin to form a heat roller fixing capsule toner.

The glass transition point Tg of the specific core material resin is 40 to 70 ° C, and particularly preferably 40 to 60 ° C. By using those having a glass transition point Tg in such a range,
Further excellent low-temperature fixability, offset resistance, and durability can be obtained. That is, when the glass transition point Tg is too low, the core material particles may become soft and the offset resistance and durability may decrease, while when the glass transition point Tg is too high, the low temperature fixability decreases. There is a tendency that sufficient low temperature fixability may not be obtained especially under low temperature and low humidity (for example, temperature 10 ° C., relative humidity 40%) environmental conditions.

In the present invention, the glass transition point Tg means a differential scanning calorimeter “low temperature DSC” (manufactured by Rigaku Denki Co., Ltd.) and a heating rate of 10 ° C./mi.
When measured by n, it means the temperature at the intersection of the extension line of the baseline below the glass transition point and the tangent line showing the maximum slope from the rising portion of the peak to the apex of the peak.

In the present invention, in the core material particles, in addition to the specific core material resin, other components may be contained, and the specific core material resin is at least 50% by weight in the core material particles.
It is preferably contained in the above proportion. If this ratio is too small, the offset resistance and durability of the capsule toner may decrease.

The specific core material resin has a molecular weight distribution divided into at least two groups, a low molecular weight component and a high molecular weight component.
In the molecular weight distribution curve measured by permeation chromatography (GPC), the maximum value on the low molecular weight component side is within the range of 1 × 10 ³ to 2 × 10 ⁴ , and the maximum value on the high molecular weight component side is 1 ×. It has at least two local maxima, such as in the range 10 ^{5 to} 2 × 10 ⁶ . By using a resin having such a specific molecular weight distribution, it becomes possible to further improve low-temperature fixability and offset resistance. Moreover, since it is possible to make the specific core resin tough by the high molecular weight component,
The outer shell and the core material particles are less likely to be broken by friction with the carrier or collision with the photoconductor, and as a result, generation of fine powder can be suppressed and contamination of the photoconductor surface can be prevented. Therefore, it is possible to stably form a clear image without fog a number of times.

On the other hand, in the above molecular weight distribution curve, when the maximum value of the low molecular weight component is too small, the blocking resistance of the capsule toner may decrease, while when the maximum value is too large, the low temperature fixability of the capsule toner is low. May decrease. Further, when the maximum value of the high molecular weight component is too small, the offset resistance and durability of the capsule toner may decrease, while when the maximum value is too large, the low temperature fixability of the capsule toner may decrease. is there.

Further, the proportion of the high molecular weight component is preferably 15% by weight or more of the vinyl polymer having a carboxy group, and particularly preferably 15 to 50% by weight. If the proportion of the high molecular weight component is too small, the offset resistance and durability of the capsule toner may decrease.

When introducing a carboxy group into a vinyl polymer containing such a high molecular weight component and a low molecular weight component, it is sufficient that at least the low molecular weight component has a carboxy group introduced. That is, the destruction of the outer shell and the core material particles caused by friction with the carrier particles or collision with the surface of the photoconductor is mainly due to the relatively fragile component having a low molecular weight in the core material particles. By, for example, cross-linking the polyvalent metal compound described later in detail to make it tough, it is possible to suppress the generation of fine powder caused by the breakage of the outer shell and the core material particles, which is a factor of the filming phenomenon.

Further, the specific core material resin has a ratio Mw / Mn value of the weight average molecular weight Mw and the number average molecular weight Mn of 4 to 40, and by such a resin, the offset resistance of the capsule toner, The mechanical durability is further improved.

In the above, the weight average molecular weight Mw and the number average molecular weight Mn
The value of can be obtained by various methods and may be slightly different depending on the difference of the measuring method, but in the present invention, it is obtained by the following measuring method.

That is, the weight average molecular weight M is determined by gel permeation chromatography (GPC) under the following conditions.
w, number average molecular weight Mn, peak molecular weight are measured. Temperature 40
1.2 ml / min of solvent (tetrahydrofuran) at ℃
The measurement is performed by injecting 3 mg of a tetrahydrofuran sample solution having a concentration of 0.2 g / 20 mg as a sample weight at a flow rate of. When measuring the molecular weight of a sample, select the measurement conditions that fall within the range in which the logarithm of the molecular weight of the calibration curve and the count number are linear, using monodisperse polystyrene standard samples of which the sample has several molecular weights. .

The reliability of the measurement results was measured under the above measurement conditions.
NBS706 polystyrene standard sample (weight average molecular weight Mw = 28.
Ratio of 8 × 10 ⁴ , number average molecular weight Mn = 13.7 × 10 ⁴ , Mw / Mn = 2.11)
Confirm that the Mw / Mn value is 2.11 ± 0.10.

Any GPC column may be used as long as it satisfies the above conditions.
Specifically, for example, TSK-GEL, GMH ₆ (manufactured by Toyo Soda Co., Ltd.) and the like can be used.

The vinyl polymer constituting the core resin is a polymer obtained by using at least one selected from a styrene monomer, an acrylic monomer and an ester monomer as an essential component. It is preferable. In addition, in order to obtain a vinyl-based weight having a carboxy group, in addition to the above-mentioned monomers, a copolymer selected from acrylic acid or methacrylic acid and derivatives thereof as an essential component may be used. Good.

Examples of the monomer having a carboxy group for such copolymerization include a hydroxyl group-containing half-ester compound having a structure obtained by an esterification reaction between an acrylic acid ester or a methacrylic acid ester or a derivative thereof and a dicarboxylic acid compound. Can be mentioned.

According to such a half-ester compound, since the carboxy group is introduced at a position that has little influence on the main chain constitution, the steric hindrance of the chemical structure is reduced, and as a result, the reaction between the carboxy group and the polyvalent metal compound is reduced. It is possible to efficiently proceed to form an ionic bond, and to obtain the specific core material resin having a good crosslinked structure.

Examples of the styrene-based monomer that can be used to obtain the vinyl-based polymer that constitutes the specific core resin include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and α-methyl. Styrene, p-ethylstyrene, 2,3-dimethyltyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, p -N-nonyl styrene, pn-decyl styrene, pn-dotecil styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,
4-dichlorostyrene and the like can be mentioned. These monomers may be used alone or in combination of two or more.

Of these, styrene is preferred. The ratio of styrene to the vinyl polymer is preferably 30 to 95% by weight, and particularly preferably 40 to 95% by weight. By selecting such a preferable ratio, the pulverization efficiency is increased in the pulverization step in the production of toner, and the toner having a desired particle size can be efficiently obtained.

Examples of the acrylic acid ester or methacrylic acid ester that can be used to obtain the vinyl-based polymer that constitutes the specific core resin include, for example, methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, acrylic acid. Propyl, octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α
-Acrylic esters such as methyl chloroacrylate; eg methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, butyl methacrylate, isobutyl methacrylate, octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, methacrylic acid-2-
Methacrylic acid esters such as ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; and the like can be mentioned.

Examples of the carboxy group-containing compound that forms the half-ester compound include malonic acid, succinic acid, glutaric acid, and other aliphatic dicarboxylic acid compounds, and phthalic acid and other aromatic dicarboxylic acid compounds.
A half-ester compound can be obtained by subjecting these compounds to an esterification reaction of an acrylic acid ester or a methacrylic acid ester having a hydroxyl group or a derivative thereof. The dicarboxylic acid compound may have a hydrogen atom substituted with a halogen group element, a lower alkyl group, an alkoxy group, or the like, or may be an acid anhydride.

The acrylic acid or methacrylic acid derivative having a hydroxyl group may be acrylic acid or methacrylic acid to which 1 mol or 2 mol or more of an alkylene oxide such as ethylene oxide or propylene oxide is added, or acrylic acid or methacrylic acid. It may be a hydroxyalkyl ester obtained by esterifying an acid with a dihydric alcohol such as propylene glycol.

The preferred half-ester compound is represented by the following general formula (A)
Can be shown as

General formula (A) However, in the general formula (A), L represents a divalent bonding group having an ester bond in the molecular chain and having 3 or more carbon atoms, and may have a substituent. R ¹ represents a hydrogen atom or a methyl group.

More preferable half-ester compounds are represented by the following general formulas (1) to (4).

General formula (1) However, in the general formula (1), R ² and R ³ represent a hydrogen atom or a methyl group, m represents an integer of 1 to 14, and n represents an integer of 0 to 8.

General formula (2) However, in the general formula (2), R ⁴ and R ^{5 each} have a hydrogen atom or a methyl group, h represents an integer of 1 to 14, X represents a hydrogen atom,
It represents a halogen group element, a lower alkyl group, or an alkoxy group.

General formula (3) However, in the general formula (3), R ⁶ has a hydrogen atom or a methyl group, j represents an integer of 3 to 6, and k represents an integer of 0 to 8.

General formula (4) However, in the general formula (4), R ⁷ has a hydrogen atom or a methyl group, i represents an integer of 3 to 6, and Y represents a hydrogen atom, a halogen group element, a lower alkyl group, or an alkoxy group.

Among the half-ester compounds represented by the general formulas (1) to (4), those represented by the general formula (1) are particularly preferable.

Examples of the half-ester compound represented by the general formula (1) include succinic acid monoacryloyloxyethyl ester, succinic acid monoacryloyloxypropyl ester, glutaric acid monoacryloyloxyethyl ester, and phthalic acid monoacryloyloxyethyl ester.
Phthalic acid monoacryloyloxypropyl ester, succinic acid monomethacryloyloxyethyl ester, succinic acid monomethacryloyloxypropyl ester, glutaric acid monomethacryloyloxyethyl ester,
Phthalic acid monomethacryloyloxyethyl ester,
Examples thereof include phthalic acid monomethacryloyloxypropyl ester.

Polymerization of a half-ester compound obtained by an esterification reaction of the above-mentioned styrene-based monomer, acrylic acid ester-based monomer or methacrylic acid ester-based monomer, hydroxyl group-containing acrylic acid or methacrylic acid-based derivative and dicarboxylic acid compound The vinyl monomer having a carboxy group is obtained in an amount of 30 to 95% by weight, particularly preferably 40 to 95% by weight, as the content ratio of the monomer unit. The acrylic ester monomer or methacrylic ester monomer is preferably 70 to 5% by weight, particularly preferably 5 to 50% by weight, and the half ester compound is preferably 0.5 to 30% by weight. And particularly preferably 1 to 20% by weight.

When the content ratio of the acrylic acid ester-based monomer or the methacrylic acid ester-based monomer exceeds 70% by weight, or when the content ratio of the half-ester compound is less than 0.5% by weight, at the time of high-temperature fixing Offset resistance may decrease, and blocking resistance and plasticizer resistance may decrease.

In the present invention, the metal element of the polyvalent metal compound reacted with the carboxy group of the vinyl polymer having a carboxy group, Cu, Ag, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, T
Examples thereof include i, Ge, Sn, V, Cr, Mo, Mn, Fe, Ni, Co, Zr and Se.

Among these various metal elements, the alkaline earth metals (Be, Mg, Ca, Sr, Ba) and the zinc group elements (Zn, Cd) are preferable, and Mg and Zn are particularly preferable.

As the polyvalent metal compound containing these metals, for example,
Of the above metal elements, fluoride, chloride, chlorinated hydrochloric acid, bromide, iodide, oxide, hydroxide, sulfide, sulfite,
Lower alkyl metal compounds such as sulfates, selenides, tellurides, nitrides, nitrates, phosphides, phosphinates, phosphates, carbonates, orthosilicates, acetates, oxalates, methyl compounds or ethyl compounds And so on. Of these, acetates of the above metal elements and oxides of the above metal elements are particularly preferable.

The amount of the polyvalent metal compound added cannot be unconditionally specified because it varies depending on the type and amount of the monomer constituting the vinyl polymer having a carboxy group, but the vinyl polymer is, for example, It is composed of the styrene-based monomer, the acrylic acid ester-based monomer or the methacrylic acid ester monomer, and the half-ester compound, and has a low molecular weight component and a high molecular weight component in the polymer. In some cases, it is about 0.1 to 1 mol with respect to 1 mol of the half-ester compound charged.

To react the polyvalent metal compound with the carboxy group of the vinyl polymer having a carboxy group, for example, in a solution containing a vinyl polymer having a carboxy group obtained by polymerizing by a solution polymerization method, Mix the polyvalent metal compound or the dispersion solution of the polyvalent metal compound, raise the temperature and remove the solvent for about 1 to 3 hours, and in the state where the temperature reaches about 150 to 180 ° C for 1 hour. The reaction is preferably completed by maintaining this temperature. In some cases, a polyvalent metal compound may be allowed to be present in the reaction system together with a solvent before starting the polymerization of the vinyl polymer having a carboxy group, or a carboxy group obtained by performing the desolventization. You may make it react by melt-kneading the vinyl-type polymer which has and a polyvalent metal compound with a roll mill, a kneader, an extruder, etc.

In this way, the specific core material resin obtained by reacting the vinyl polymer having a carboxy group with the polyvalent metal compound has an ionic bond between the carboxy group of the vinyl polymer and the polyvalent metal atom. And a kind of crosslinked structure is formed by this ionic bond. This ionic bond is a much slower bond than a covalent bond.

In the present invention, as the specific core resin, those having at least two maximum values in the molecular weight distribution curve can be preferably used as described above, but the method for obtaining such a resin is not particularly limited. . For example, the first stage polymerization for obtaining either the high molecular weight component or the low molecular weight component is carried out, and one component thus obtained is dissolved in the monomer composition for obtaining the other component. By carrying out the second-stage polymerization and thereby producing the other component, a polymer having at least two local maximum values in the molecular weight distribution curve can be obtained as a result. Thus, the polymer obtained by the two-step polymerization is presumed to be a mixture of the low molecular weight component and the high molecular weight component uniformly at the molecular level.

This two-stage polymerization can be carried out by, for example, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method or the like, but a solution polymerization method is particularly preferable.

Further, the polymer having at least two local maximum values in the molecular weight distribution curve can be also obtained by mixing a low molecular weight polymer component and a high molecular weight polymer component, but the polymer obtained by mixing May not be uniformly mixed at the molecular level, so that the above two-stage polymerization is preferred.

In the present invention, a monomer unit such as vinyl acetate, vinyl propionate, vinyl chloride or ethylene may be contained in the molecular chain of the specific core material resin as long as the characteristics are not impaired. Further, a polymer or copolymer of these monomers may be mixed in the core material particles. Further, other resin may be mixed in the core material particles, if necessary. Examples of such other resin include styrene-acrylic resin, polyurethane resin, styrene-
Butadiene-based resin, polyester resin, epoxy resin and the like can be mentioned.

In the present invention, the surface of the core material particles is coated with an outer shell made of a thermoplastic resin. As such a thermoplastic resin, those conventionally used as a resin for toner can be used. Specific examples include vinyl polymers, polyester resins, epoxy resins and polyurethane resins. Of these, vinyl polymers and polyester resins are particularly preferable. Specifically, for example, styrene-n-butyl acrylate copolymer, styrene-methyl methacrylate-n-butyl methacrylate copolymer, terephthalic acid-bisphenol A.
Examples thereof include propylene oxide condensates.

The glass transition point Tg of the thermoplastic resin forming the outer shell is
It is preferably 50 ° C or higher. If the glass transition point Tg is too small, the blocking resistance of the capsule toner may be reduced.

The thermoplastic resin forming the outer shell preferably has a ratio Mw / Mn of polymerization average molecular weight Mw to number average molecular weight Mn of 7.0 or more. When the value of the ratio Mw / Mn is too small, the offset resistance of the capsule toner may be reduced.

The capsule toner of the present invention, if necessary, a colorant,
So-called toner components such as a charge control agent and a fixing property improving auxiliary agent may be added. These toner components may be contained in the core material particles or may be contained in the outer shell. Further, the capsule toner contains additives such as a fluidity improver, an abrasive, and a cleaning improver in a state of being adhered to the outer shell or in a state of being hammered into the outer shell and held. Good.

Examples of colorants include carbon black, nigrosine dye, aniline blue, chalco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, These mixtures, etc. can be mentioned.

Examples of the charge control agent include metal complex dyes, nigrosine dyes and ammonium compounds.

Examples of the fixing property improving aid include polyolefins such as polyethylene and polypropylene. In particular, a polyolefin having a softening point Tsp by the ring and ball method of 70 to 150 ° C. is preferable, and further the softening iron Tsp is 120 to 15
A 0 ° C. polyolefin is preferred.

Inorganic fine particles can be preferably used as the fluidity improver and the abrasive. The primary particle diameter of the inorganic fine particles is preferably 5 μm to 2 μm, and particularly 5 μm.
It is preferably about 500 μm. The specific surface area by the BET method is preferably 20 to 500 m ² / g. The use ratio of the inorganic fine particles is preferably 0.01 to 5% by weight of the capsule toner, and particularly preferably 0.01 to 2.0% by weight. Specific examples of the inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, silica lime, diatomaceous earth, and chromium oxide. , Cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like. Fine silica powder is particularly preferable.

The fine silica powder is a fine powder having a Si-O-Si bond and may be produced by a dry method or a wet method. In addition to anhydrous silicon dioxide, any of aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate may be used, but those containing 85% by weight or more of Si—O ₂ are preferable. Although various commercially available products are available as specific examples of fine silica powder, those having a hydrophobic group on the surface of the fine particles are particularly preferable. For example, "Aerosil R-972", "Aerosil R-974", "Aerosil R" -805 "," Aerosil R-
"812" (above, made by Aerosil Co., Ltd.), "Taranox 500"
(Manufactured by Tarco) can be preferably used. In addition to these, fine particles of silica surface-treated with a silane coupling agent, a titanium coupling agent, a silicone oil, a silicone oil having an amine in a side chain, or the like can be used.

Examples of the cleaning property improver include fatty acid metal salts such as zinc stearate, calcium stearate and stearic acid, and polymer particles such as methyl methacrylate particles and styrene particles.

Further, when the magnetic toner is used, one or both of the core material particles and the outer shell may contain magnetic fine particles.

As such a magnetic material, ferrite, magnetite or other iron, nickel, a metal or alloy exhibiting ferromagnetism such as cobalt, a compound containing these elements, or containing no ferromagnetic element, but by subjecting to an appropriate heat treatment Mention may be made of alloys which become ferromagnetic, for example manganese-copper-aluminum, manganese-copper-tin, alloys of the type called Heusler alloys containing manganese and copper, chromium dioxide and others. It is preferable that the magnetic substance is uniformly dispersed and contained in the form of fine powder having an average particle diameter of 0.1 to 1 μm. And the content ratio of the magnetic substance is
It is preferably 10 to 70 parts by weight, and particularly preferably 20 to 50 parts by weight, with respect to 100 parts by weight of the encapsulated toner.

In the present invention, the core material particles can be produced by the following method, for example.

(1) The specific core resin for forming core particles and a toner component such as a coloring agent used as needed are melt-kneaded by, for example, an extruder, and after cooling, finely ground by a jet mill or the like. Then, this is classified to obtain core material particles having a desired particle diameter.

(2) The specific core resin for forming core particles and a toner component such as a coloring agent used as necessary are melt-kneaded by, for example, an extruder, and a spray dryer in a molten state. A method of obtaining core material particles having a desired particle size by spraying with, for example.

(3) The specific core resin for forming the core particles and a toner component such as a coloring agent used as necessary are melt-kneaded by, for example, an extruder, and are melted in a liquid in a molten state. A method for obtaining core material particles having a desired particle diameter by dispersing the core material particles in a desired amount.

Further, in the present invention, as a method for providing an outer shell on the surface of the core material particles, a coating solution obtained by dissolving a thermoplastic resin for forming the outer shell in a solvent is used, for example, a dipping method, a spray drying method, a fluidization method. It is possible to use a method in which a coating layer is formed by coating the surface of the core material particles by a method such as a bed method, heating and drying to volatilize and remove the solvent, and curing the coating layer during or after drying. For example, when the coating layer is formed by the fluidized bed method, in the fluidized bed apparatus, the core material particles are raised to the height of equilibrium by the rising pressurized gas flow, and then when the core material particles fall again. The coating solution can be spray-coated up to this time, and this spray-coating can be repeated to form an outer shell.

The capsule toner of the present invention may be a two-component developer in combination with a carrier, or may be a magnetic capsule toner containing a magnetic substance and a one-component developer composed of only the magnetic capsule toner. It may be one that does.

The capsulated toner of the present invention is a capsulated toner for fixing on a heat roller, and is used for image formation, for example, as follows. That is, in the electrophotographic method, an electrostatic latent image formed on a photosensitive member which is a latent image carrier is developed with a two-component developer or a one-component developer constituted by using the capsule toner of the present invention, The obtained toner image is electrostatically transferred onto a support made of paper or the like, and then the transferred toner is fixed by a heat roller fixing method to form a fixed image.

The heat roller fixing device used in the heat roller fixing method is usually composed of a heat roller, a pressure roller arranged in contact with the heat roller, and a heat source. In addition, a cleaning roller is arranged in contact with the heat roller as needed. While the temperature of the heat roller is kept within a certain range by the heating source, the toner is transferred directly between the heat roller and the pressure roller, so that the toner directly contacts the heat roller and the toner Is thermally fixed to the support.

The surface material of the heat roller is preferably a fluorine-based substance or a silicone-based substance, and the durability of the heat roller fixing device can be remarkably improved by the synergistic effect with the capsule toner of the present invention.

[Specific Example]

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

<Production of Resin A> (for the present invention) A separable flask having a capacity of 3 and equipped with a thermometer, a stirrer, a nitrogen gas introducing pipe, and a flow-down condenser has 500 m of toluene.
l was charged and nitrogen gas was introduced through a nitrogen gas introduction tube to make the inside of the flask an inert atmosphere, and then heated in an oil bath to the reflux temperature of toluene.

Next, 200 g of styrene, 80 g of n-butyl acrylate,
20 g of methyl methacrylate, benzoyl peroxide
A composition of 0.9 g of a high molecular weight component was placed in a flask, kept at the reflux temperature and reacted for 14 hours to form a high molecular weight polymer.

Next, a low molecular weight component consisting of 382 g of styrene, 35 g of α-methylstyrene, 210 g of n-butyl acrylate, 73 g of monoacryloyloxyethyl succinate, and 42 g of benzoyl peroxide was placed in a fuscosco containing the solution of the above high molecular weight polymer. The polymerization reaction was carried out while gradually dropping the composition. After the dropping of the composition of the low molecular weight component was completed, a polymerization reaction was further performed for 4 hours to form a low molecular weight polymer.

Next, in a flask containing a solution of the high molecular weight polymer and the low molecular weight polymer, zinc oxide which is a polyvalent metal compound is placed.
8 g was added, and the reaction was carried out for 2 hours with stirring at the reflux temperature.

After completion of the reaction, the solvent toluene was distilled off under reduced pressure,
A resin obtained by reacting a carboxy group of a low molecular weight component with a polyvalent metal compound was obtained. This is designated as "resin A".

This resin A has maximum values at 7.5 × 10 ³ and 2.8 × 10 ⁵ , respectively, in the molecular weight distribution curve by gel permeation chromatography (HLC-802 UR, GMH ₆ column, manufactured by Toyo Soda Co., Ltd.), Average molecular weight Mw is 1.2 × 10 ⁵ , ratio
The Mw / Mn value is 17.1, and the glass transition point Tg is 46 ° C.

<Production of Resin B> (For Present Invention) In the production of Resin A, as a composition of a high molecular weight component,
A composition of a high molecular weight component consisting of 140 g of styrene, 80 g of n-butyl acrylate, 60 g of n-butyl methacrylate, 20 g of methyl methacrylate, and 1.5 g of azobisisobutyronitrile was used.
Acetic acid was used as a polyvalent metal compound using 7 g, α-methyl styrene 70 g, 2-ethylhexyl acrylate 210 g, methyl methacrylate 35 g, monoacryloyloxyethyl isophthalate 48 g, and benzoyl peroxide 35 g. A resin obtained by reacting a carboxy group of a low molecular weight component with a polyvalent metal compound was obtained in the same manner as in the production of Resin A except that 22.4 g of zinc was used. This is designated as "resin B".

This resin B has a molecular weight distribution curve by gel permeation chromatography of 1.2 × 10 ⁴ and
Each has a maximum value at 2.4 × 10 ⁵ , and the weight average molecular weight Mw is
1.15 × 10 ⁵ , ratio Mw / Mn value of 9.5, glass transition temperature Tg of 48 ℃
Is.

<Production of Resin a> (For Comparison) In the production of Resin A, a resin for comparison was obtained in the same manner except that zinc oxide which is a polyvalent metal compound was not used. This is designated as "resin a".

This resin a has a molecular weight distribution curve by gel permeation chromatography of 7.1 × 10 ³ and
Each has a maximum value at 2.8 × 10 ⁵ , and the weight average molecular weight Mw is
1.18 × 10 ⁵ , ratio Mw / Mn value 18.1, glass transition point Tg 43 ° C
Is.

<Example 1> (1) Manufacture of core material particles 100 parts by weight of the above resin A, 10 parts by weight of carbon black "Mogal L" (manufactured by Cabot Corporation), and polypropylene "Viscor 660P" (softening point Tsp: 130 C., 5 parts by weight of Sanyo Kasei Co., Ltd.) was mixed with a V-type blender, melt-kneaded with two rolls, cooled, coarsely crushed with a hammer mill, and further finely pulverized with a jet mill.
The core material particles having a particle size of 1 to 30 μm were obtained by classification with an air classifier. This is designated as "core material particle 1".

(2) Manufacture of outer shell Styrene-methyl methacrylate-acrylic acid-n-butyl acrylate copolymer (copolymerization weight ratio = 65: 15: 5: 1
To 500 parts by weight of the emulsified dispersion liquid (solid content: 10% by weight) of 5), 300 parts by weight of the core material particles 1 was added and sufficiently dispersed, and then spray-dried at an inlet temperature of 180 ° C and an outlet temperature of 60 ° C. Then, an outer shell made of the above copolymer was formed on the surface of the core material particles to obtain a capsule toner powder.

To 50 parts by weight of this capsule toner powder, a hydrophobic silica fine powder "Aerosil R-972" (manufactured by Nippon Aerosil Co., Ltd.)
0.4 part by weight was added and mixed to obtain a capsule toner according to the present invention. This is designated as "toner 1".

(3) Preparation of Developer 950 of a resin-coated carrier obtained by coating the surface of copper-zinc ferrite particles with styrene-methylmethacrylate copolymer (copolymerization weight ratio = 70: 30) on the above-mentioned parts by weight of Toner 1. A developer was prepared by mixing parts by weight. This is referred to as "developer 1".

(4) Actual shooting test Using the above developer 1, an electrophotographic copying machine "U-Bix 160
0 "(Konishi Rokusha Kogyo Co., Ltd.) to form and develop an electrostatic latent image, transfer the resulting toner image onto a transfer paper, and fix it with a heat roller fixing device to form a copied image. Then, the following items were evaluated.

Minimum fixing temperature After making an unfixed image with the above copying machine, the surface layer is a heat roller with a diameter of 30φ made of Teflon (polytetrafluoroethylene manufactured by DuPont) and the surface layer is silicone rubber "KE-1300RVT" (Shin-Etsu A thermal roller fixing device consisting of a pressure roller formed by Kagaku Kogyo Co., Ltd. was used to transfer a toner image of the sample toner transferred onto a transfer paper of 64 g / m ² with a linear speed of the thermal roller of 70 mm / sec and a linear pressure of 0.8. For fixing operation with kg / cm and nip width of 4.9 mm, set the temperature of the heat roller to 100-240 ℃.
The temperature is increased stepwise by 5 ° C. within each range, and the formed fixed image is repeatedly rubbed with Kimwipe, and the minimum fixing temperature is set for the fixed image showing sufficient rubbing resistance. Temperature. The heat roller fixing device used here does not have a silicone oil supply mechanism. The environmental conditions are normal temperature and pressure (temperature 20 ° C, relative humidity 60%), low temperature and low humidity (temperature 10 ° C, relative humidity 40%).
There are two ways.

Offset generation temperature The measurement of the offset generation temperature is in accordance with the measurement of the above-mentioned minimum fixing temperature, but after creating an unfixed image with the above copying machine,
The toner image is transferred and the fixing process is performed by the above heat roller fixing device, and then a blank transfer paper is sent to the heat roller fixing device under the same conditions to visually observe whether or not toner stains occur. The operation was repeated in the state where the set temperature of the heat roller of the heat roller fixing device was sequentially increased, and the minimum set temperature at which the toner was contaminated was defined as the offset generation temperature. The environmental conditions are normal temperature and pressure (temperature 20
℃, 60% relative humidity, low temperature and low humidity (temperature 10 ℃, relative humidity)
40%).

Fixable temperature range The difference between the offset generation temperature and the minimum fixing temperature measured as described above was defined as the fixable temperature range.

Blocking resistance The blocking resistance is tested at a temperature of 55 ° C and a relative humidity of 60%.
The toner was allowed to stand for 1 day under the environmental conditions of No. 1 and judged by the presence or absence of agglomerates in the toner. When no agglomerates were observed, "○" was given, and when agglomerates were observed, "x" was given. .

Durability of the fuser when the environmental conditions are low temperature and low humidity (temperature 10 ° C, relative humidity 40%) Under the low temperature and low humidity (temperature 10 ° C, relative humidity 40%) electrophotographic copying machine "U-Bix 1600" With the set temperature of the fixing device set to 10 ° C. higher than the above minimum fixing temperature, a number of live-action tests were performed, and the heat roller dirt, the heat roller cleaning roller dirt, and the pressure roller The durability of the fixing device was evaluated by the stain, the occurrence of offset, the occurrence of paper jam, and the stain on the back surface of the transfer paper.

Fog Using a "Sakura Densitometer" (manufactured by Konishi Rokusha Kogyo Co., Ltd.), the relative density with respect to the developed image of a white background portion having a document density of 0.0 was measured and judged. The white background reflection density is 0.0
And In the evaluation, when the relative concentration was less than 0.01, it was evaluated as “◯”, when it was 0.01 or more and less than 0.03, it was evaluated as “Δ”, and when it was 0.03 or more, it was evaluated as “x”.

Image Quality The actual copying test was continuously performed 30,000 times with the above copying machine, and the sharpness of the copied image was examined at the initial stage of image formation and after 30,000 times. As for the evaluation, good ones were evaluated as "○", and those that were not good but were at a practical level were evaluated as "△".
Those that were inferior and had problems in practical use were marked with "x".

Cleanability A continuous copying test was conducted 30,000 times with the above copying machine, and every time the number of times of copying reached 5,000, the surface of the photoconductor after being cleaned by the cleaning blade was visually observed to confirm that the adhered matter It was judged by the presence or absence. In the evaluation, good ones were evaluated as “◯”, those which were not good but were in a practical level were evaluated as “Δ”, and those which were inferior and had a problem in practical use were evaluated as “x”.

Filming resistance After conducting a continuous copying test for 30,000 times with the above copying machine, the surface of the carrier particles, the surface of the photoconductor, and the cleaning blade are observed with an electron microscope or visually, and judged by the presence or absence of adhered substances. did. The case where the adhered matter was not recognized was marked with “◯”, the case where the adhered matter was slightly recognized was marked with “Δ”, and the case where the adhered matter was considerably recognized was marked with “x”.

The above results are shown in Table 1 below.

<Example 2> (1) Manufacture of core material particles 100 parts by weight of the above resin B, 10 parts by weight of carbon black "Mogal L" (manufactured by Cabot), and 5 parts of polyethylene (softening point Tsp: 135 ° C) Parts by weight were treated in the same manner as in Example 1 to obtain core material particles. This is designated as "core material particle 2".

(2) Production of outer shell A capsule toner powder was obtained in the same manner as in Example 1 except that the above core material particles 2 were used.

A capsule toner according to the present invention was obtained in the same manner as in Example 1 except that this capsule toner powder was used. This is designated as "toner 2".

(3) Preparation of Developer A developer was prepared in the same manner as in Example 1 except that Toner 2 was used. This is referred to as "developer 2".

(4) Actual Photographing Test Using the developer 2 described above, an actual photographing test was conducted in the same manner as in Example 1, and each item was evaluated. The results are also shown in Table 1 below.

Comparative Example 1 A developer was prepared in the same manner as in Example 1 except that the core particle 1 obtained in the same manner as in Example 1 was used as a toner (hereinafter referred to as “comparative toner 1”). Using this developer, an actual copying test was conducted in the same manner as in Example 1, and each item was evaluated. The results are also shown in Table 1 below.

<Comparative Example 2> 100 parts by weight of the resin a for comparison and 10 parts by weight of carbon black "Mogal L" (manufactured by Cabot Corporation) were treated in the same manner as in Example 1 to prepare core particles for comparison. Got

A capsule toner for comparison (hereinafter referred to as "comparative toner 2") was obtained in the same manner as in Example 1 except that the core particles were used.

A developer was prepared using this comparative toner 2 in the same manner as in Example 1, and a real copying test was conducted in the same manner as in Example 1 using this developer, and each item was evaluated. The results are also shown in Table 1 below.

As can be seen from the results in Table 1, Toner 1 of the present invention
In No. 2 and No. 2, both have excellent low-temperature fixability, particularly low-temperature fixability even under low-temperature and low-humidity environmental conditions, and also have excellent offset resistance, and in the fixable temperature range. Is as wide as 75-80 ℃. Also,
The blocking resistance is good, a clear copy image without fog is obtained even after 30,000 times of the actual copying test, and the cleaning property and the filming resistance are also good.
Further, even under environmental conditions of low temperature and low humidity, the image forming process can be smoothly performed without causing trouble such as paper jam due to less contamination of the heat roller.

On the other hand, Comparative Toner 1 does not have an outer shell and thus has sufficient low-temperature fixability, but has poor blocking resistance, resulting in poor triboelectricity with the carrier. The copied image becomes fogged and unclear. In addition, the cleaning property and the filming resistance are poor and the durability is low. Further, under the environmental conditions of low temperature and low humidity, the heat roller is significantly contaminated, which causes a paper jam, which makes it difficult to smoothly perform the image forming process.

Further, in Comparative Toner 2, since the comparative resin a forming the core material particles is not cross-linked by the polyvalent metal compound, the offset resistance is low and the heat roller is significantly contaminated. Problems such as paper jams tend to occur. Further, after 30,000 times of the actual shooting test, fogging occurs, the image becomes unclear, and the durability is low.

Claims (4)

[Claims] 1. A heat roller fixing capsule toner comprising fusible core particles and an outer shell made of a thermoplastic resin provided so as to cover the surfaces of the core particles, wherein the fusible core particles are A core polymer having a glass transition point Tg of 40 to 70 ° C., which is obtained by reacting a polyvalent metal compound with the carboxy group of a vinyl polymer having a carboxy group, wherein the core resin is It has a molecular weight distribution of at least two groups of a low molecular weight component and a high molecular weight component, and the molecular weight distribution has a maximum value of 1 × 10 ³ to 2 in a molecular weight distribution curve by gel permeation chromatography. Capsule toner for heat roller fixing, characterized in that it is in the range of × 10 ⁴ , and the maximum value of the high molecular weight component is in the range of 1 × 10 ⁵ to 2 × 10 ⁶ . 2. The heat roller fixing according to claim 1, wherein the core material resin has a ratio Mw / Mn of weight average molecular weight Mw to number average molecular weight Mn of 4 to 40. Capsule toner. 3. The ratio of the core resin in the fusible core particles is
The heat roller fixing capsule toner according to claim 1 or 2, wherein the content is 50% by weight or more. 4. A polymer obtained from a styrene monomer, an acrylic acid ester or a methacrylic acid ester, and a monomer represented by the following general formula (A), and a polyvalent metal compound. The heat-roller fixing capsule toner according to claim 1, 2, or 3, which is a polymer obtained by reacting General formula (A) (However, in the general formula (A), L represents a divalent bonding group having an ester bond in the molecular chain and having 3 or more carbon atoms, and may have a substituent. R ¹ is a hydrogen atom or methyl. Represents a group.)