JPS63217356A - Capsuled toner for heat roller fixing - Google Patents

Abstract

PURPOSE:To improve the fixability of a toner at low temp. and the offsetting resistance by incorporating a resin obtd. by allowing carboxy groups in a vinyl polymer to react with a multivalent metallic compd. into the core particles. CONSTITUTION:A toner is composed of meltable core particles and thermoplastic resin shells formed on the surfaces of the core particles. The core particles contain preferably >=50wt.% core resin obtd. by allowing carboxy groups in a vinyl polymer such as a (meth)acrylate copolymer to react with a multivalent metallic compd. such as zinc oxide. The core resin is preferably a resin contg. low and high mol.wt. components and having two peaks at 1,000-20,000 and 100,000-2,000,000 on the mol.wt. distribution curve and >=3.5 ratio of the weight average mol.wt. to the number average mol.wt.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a capsule toner used for developing electrostatic latent images formed in electrophotography, electrostatic printing, electrostatic recording, etc. This invention relates to a capsule toner for heat roller fixing.

[Background of the invention]

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

Conventional methods for fixing toner images include a method in which the toner is heated and melted in a non-contact state using a heater;
Some of the known methods include fixing by dissolving the toner with an organic solvent, fixing by pressurizing the toner, and so-called hot roller fixing method in which a heated roller is brought into direct contact with the toner to melt and press the toner to fix it. The hot roller fixing method is widely used because it has high thermal efficiency and enables high-speed fixing.

However, in recent years, efforts have been made to (a) suppress deterioration caused by overheating of copying machines, and (b) shorten the warm-up time required for the heat roller to rise to a temperature capable of fixing after the heat roller fixing device is activated. (c) To reduce the temperature drop of the heat roller due to the absorption of heat by an image support such as transfer paper, and to enable stable image formation over a number of consecutive times; and (d) copying. From the viewpoint of downsizing machines and improving safety, there is a strong demand to reduce the power consumption of the heater built into the fuser and to enable the fusing process while keeping the heat roller temperature lower. There is.

Therefore, toners are required to (1) be able to achieve good fixing at even lower temperatures, that is, have excellent low-temperature fixing properties, and basically meet the following conditions: is necessary.

(2) In the heat roller fixing method, which is preferred as a fixing method, there is an offset phenomenon, that is, a part of the toner that makes up the image is transferred to the surface of the heat roller during fixing, and this is transferred again to the transfer paper that is sent next. Since the phenomenon of smearing images is likely to occur, toner should be given performance that prevents transfer to a hot roller, that is, anti-offset property.

(3) It should be able to exist stably as a powder without agglomerating under the environmental conditions of use or storage, that is, it should have excellent blocking resistance.

(4) It has good triboelectric charging properties, and (5) the development process, transfer process, and cleaning process can be carried out well and clear images without capri can be obtained.

(5) The so-called filming phenomenon in which toner substances adhere to the surface of a photoreceptor or carrier particles is suppressed, and images can be stably formed many times.

Conventionally, by using a capsule toner as a toner, the capsule toner is composed of core particles and an outer shell provided to cover the surface of the core particles.
Techniques have been proposed to improve low-temperature fixing properties. This type of capsule toner uses a low melting point compound or a material with a low glass transition point as core material particles in order to improve meltability at low temperatures. Specifically, the following techniques are disclosed.

■Technology in which core material particles are composed of wax
(Refer to Publication No.-1588).

(2) A technique in which the core particles are made of polyester crosslinked with a polyvalent metal compound (see Japanese Patent Laid-Open No. 174957/1983).

■Technology in which core material particles are composed of low-melting point polyester (
(See Japanese Unexamined Patent Publication No. 176642/1983).

■Technology in which the core material particles are made of a low molecular weight styrene-acrylic resin with a gel content of 20 to 70% (see JP-A-58-176643)
.

■Technique 4+j in which the core material particles are composed of amorphous polyester with a glass transition point of 60°C or less (Japanese Patent Application Laid-Open No. 58-205
(See Publication No. 161).

(2) A technique in which the core material particles are composed of a crosslinked vinyl polymer having a glass transition point of 55°C or less and a gel content of 20% or more (see Japanese Patent Laid-Open No. 58-205161).

■The core material particles have a glass transition point of 60℃ or less and an acid value of l.
Technology composed of amorphous polyester of O~150 (
(See Japanese Patent Application Laid-Open No. 58-205163).

■Technology in which the core material particles are composed of amorphous polyester and a polyvalent metal compound (Japanese Unexamined Patent Publication No. 58-2051
(See Publication No. 64).

[Problem that the invention seeks to solve]

However, in the above technique (2), when a hot roller fixing method is applied as the fixing method, the offset resistance is considerably poor and the practicality is extremely low.

In addition, although it is recognized that the above technologies (1) to (2) have improved performance under the environmental conditions of normal temperature and normal pressure (e.g., temperature 20°C, relative humidity 60%), compared to the above technology (2), they still have no offset resistance. However, there is a problem in that the temperature range in which fixing can be performed without causing the occurrence of an offset phenomenon is narrow, and the practicality of the fixing method is still low.

Moreover, low temperature and low humidity (e.g. temperature 10℃, relative humidity 40%)
), the temperature of the image support such as transfer paper is low, so the toner tends to be insufficiently melted during fixing, resulting in poorly fixed toner adhering to the rollers that make up the fixing device. It accumulates and contaminates the roller, which causes conveyance failures such as clogging and shortens the useful life of the roller.

As described above, the reality is that, depending on the conventional capsule toner, a fully satisfactory capsule toner for heat roller fixation has not yet been obtained.

This is because conventional capsule toners are basically intended to be applied to pressure fixing methods. That is, the toner is designed to be suitable for the fixing method to which it is applied, and for example, when a toner designed for pressure fixing is applied to hot roller fixing, problems such as off-setting phenomenon may occur. Dots are generated, and it is not always possible to form a sufficient copy image.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and an object thereof is to have excellent low-temperature fixing properties and offset resistance, and to have a wide practical fixing temperature range, and to have a low-temperature, low-humidity environmental condition. It maintains its excellent low-temperature fixing properties even under low temperatures, and it is possible to fix without staining the rollers that make up the fixing device.It also has excellent blocking resistance, frictional charging properties, and filming resistance. It is an object of the present invention to provide a capsule toner for hot roller fixing that can stably form fog-free and clear images many times.

[Means for solving problems]

The capsule toner for heat roller fixing of the present invention includes meltable core particles and an outer shell made of a thermoplastic resin provided to cover the surface of the core particles. The meltable core material particles are characterized in that they contain a core material resin obtained by reacting a polyvalent metal compound with the carboxy group of a vinyl polymer having a carboxy group.

[Function and effect of the invention]

According to the capsule toner for heat roller fixing of the present invention, the core material particles contain a core material resin obtained by reacting a polyvalent metal compound with the carboxy group of a vinyl polymer having a carboxy group, and Since the material resin has a structure cross-linked by so-called ionic bonds with polyvalent metal compounds, this cross-linked structure allows the toner to have an appropriate viscoelasticity when melted even if the core material resin has a low glass transition point Tg. Due to its small size, toner material is less likely to transfer to the heat roller of the heat roller fixing device, resulting in excellent offset resistance.
Moreover, this crosslinked structure has a weaker bonding force than normal covalent bonds, so even though it has a glass transition point Tg comparable to that of a resin with a crosslinked structure based on covalent bonds, it can be fixed at a lower temperature. Excellent low-temperature fixing properties are exhibited, especially under low-temperature, low-humidity environmental conditions. As described above, since the toner can be fixed at a lower temperature without causing the offset phenomenon, the fixable temperature range is sufficiently widened, and a toner which is extremely excellent in practical use can be obtained.

Since the core particles are covered with an outer shell made of thermoplastic resin, the outer shell provides excellent blocking resistance, good triboelectric charging properties, cleaning properties, and excellent anti-filming properties. .

[Specific structure of the invention]

Hereinafter, a specific configuration of the present invention will be explained.

In the present invention, basically, a core material resin (hereinafter referred to as "specific core material resin") obtained by reacting a polyvalent metal compound with the carboxy group of a vinyl polymer having a carboxy group is used.
Also called. ) The surface of the core particle containing the above particles is covered with an outer shell made of a thermoplastic resin to constitute a capsule toner for heat roller fixation.

The glass transition point 'rg of the specific core material resin is 40 to 7.
By selecting a material having a glass transition point Tg in this range, preferably 0°C, particularly preferably 40 to 60°C, even better low-temperature fixing properties, offset resistance, and durability can be achieved. is obtained. That is, when the glass transition point Tg is too small, the core material particles become soft and the offset resistance and durability may be reduced, while when the glass transition point Tg is too large, the low-temperature fixing properties are reduced. There is a tendency that sufficient low-temperature fixability may not be obtained, particularly under environmental conditions of low temperature and low m (for example, temperature of 10° C. and relative humidity of 40%).

In the present invention, the glass transition point Tg is the extension of the baseline below the glass transition point when measured using a differential scanning calorimeter "low temperature DSCJ (manufactured by Rigaku Denki Co., Ltd.) at a heating rate of 10°C/Ilin." This is the temperature at the intersection of the line and the tangent line showing the maximum slope from the rising part of the peak to the top of the peak.

In the present invention, the core material particles may contain other components in addition to the specific core material resin, and the specific core material resin accounts for at least 50% by weight or more in the core material particles. It is preferable that the content is as follows. If this ratio is too small, the offset resistance and durability of the capsule toner may deteriorate.

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, and in a molecular weight distribution curve measured by gel permeation chromatography (GPC), the low molecular weight The maximum value on the component side is within the range of lXl0' to 2X10',
It is preferable that the polymer has at least two maximum values such that the maximum value on the high molecular weight component side is within the range of 1X10' to 2X10'. By selecting a resin having such a preferable molecular weight distribution, it is possible to further improve low-temperature fixing properties and anti-offset properties.

In addition, since it is possible to make the specific core material resin strong with a high molecular weight component, the outer shell and core material particles are less likely to be destroyed by friction with the carrier or collision with the photoreceptor. As a result, generation of fine powder can be suppressed, and contamination of the surface of the photoreceptor can be prevented.

Therefore, it is possible to stably form a clear image without fog over a large 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 fixing property of the capsule toner may decrease. Furthermore, 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 deteriorate.

Further, the proportion of the high molecular weight component is preferably 15% by weight or more of the vinyl polymer having a carboxy group,
In particular, it is 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 be reduced.

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 the carboxy group is introduced into at least the low molecular weight component. In other words, the destruction of the outer shell and core particles caused by friction with carrier particles or collision with the photoreceptor surface is mainly caused by the relatively brittle components of low molecular weight in the core particles. By crosslinking and making it tough using a polyvalent metal compound, which will be described in detail later, it is possible to suppress the generation of fine powder caused by the destruction of the outer shell and core particles, which is a factor in the filming phenomenon.

Further, the specific core material resin preferably has a ratio Mw/Mn of its weight average molecular weight to number average molecular llMn of 3.5 or more, particularly preferably 4 to 40. The value of this ratio Mw/Mn is 3.5 or more, and even 4
By selecting one having a molecular weight of 40 to 40, the capsule toner will have even better offset resistance and mechanical durability.

In the above, weight average molecular weight and number average molecular weight M
The value of n can be determined by various methods, and there are slight differences depending on the measurement method, but in the present invention, it is determined by the following measurement method.

That is, the weight average molecular weight is 31 Mw, the number average molecular weight is 11 Mn, and the peak molecular weight is measured by gel perminy silane chromatography (GPC) under the conditions described below. At a temperature of 40°C, the solvent (tetrahydrofuran)
was flowed at a flow rate of 1.2-min/min, and the concentration was 0.2 g/20d.
The sample solution of tetrahydrofuran is expressed as 3I1 as the sample weight.
When measuring the molecular weight of a sample by injecting
Measurement conditions are selected in which the molecular weight of the sample falls within a range in which the logarithm of the molecular weight of the N-line prepared using several types of monodisperse polystyrene standard samples and the count number form a straight line.

The reliability of the measurement results is based on the N B S 706 polystyrene standard sample (weight average molecular weight Mw - 28,8X10' + number average molecular weight Mn = 13) measured under the above measurement conditions.
．． 7x 10', Mw/Mn=2.11) ratio Mw
This is confirmed by checking that the value of /Mn is 2.11±0.10.

Further, as the GPC column to be used, any column may be used as long as it satisfies the above conditions. Specifically, for example, TSK-GEL, GMH, (manufactured by Toyo Soda Co., Ltd.), etc. may be used. Can be done.

The vinyl polymer constituting the core resin is, for example, a polymer obtained using at least one selected from styrene monomers, acrylic monomers, and ester monomers as an essential component. In addition, in order to obtain a vinyl polymer having a carboxyl group, in addition to the above monomers, a monomer selected from acrylic acid or methacrylic acid and derivatives thereof is used as an essential component. Copolymerization is sufficient.

Monomers having a carboxyl group for such copolymerization include half-ester compounds having a structure obtained by an esterification reaction between a hydroxyl group-containing acrylic ester or methacrylic ester, or a derivative thereof, and a dicarboxylic acid compound. can be mentioned.

According to such half-ester compounds, the carboxyl group is introduced at a position that has little effect on the main chain structure, so the steric hindrance of the chemical structure is reduced, and as a result, the reaction between the carboxyl group and the polyvalent metal compound is reduced. The process proceeds efficiently to form ionic bonds, and the specific core material resin having a good crosslinked structure can be obtained.

Examples of styrenic monomers that can be used to obtain the vinyl polymer constituting the specific core resin include styrene, O-methylstyrene, m-methylstyrene, p-methylstyrene, and α-methyl. Styrene, p-ethylstyrene, 2,3-dimethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-te
rt-butylstyrene, p-n-hexylstyrene, p
-n-octylstyrene, p-n-nonylstyrene, p
-n-decylstyrene, p-n-dodecylstyrene, p
-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, and the like. These monomers may be used alone or
Alternatively, a combination of a plurality of them may be used.

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

Examples of the acrylic ester or methacrylic ester that can be used to obtain the vinyl polymer constituting the specific core resin include methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, and acrylic acid. propyl, octyl acrylate,
Acrylic acid esters such as dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, and methyl α-chloroacrylate; for example, methyl methacrylate, methacrylic acid Ethyl, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylamine ethyl methacrylate, diethylamino methacrylate Methacrylic acid esters such as ethyl; etc. can be mentioned.

Examples of the carboxyl group-containing compound forming the half-ester compound include aliphatic dicarboxylic acid compounds such as malonic acid, succinic acid, and glutaric acid, and aromatic dicarboxylic acid compounds such as phthalic acid.

Half-ester compounds can be obtained by subjecting these compounds to an esterification reaction with acrylic esters, methacrylic esters, or derivatives thereof having a hydroxyl group. 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 derivative of acrylic acid or methacrylic acid having a hydroxyl group may be one in which 1 or 2 moles or more of alkylene oxide such as ethylene oxide or propylene oxide is added to acrylic acid or methacrylic acid, or acrylic acid or methacrylic acid It may also be a hydroxyalkyl ester obtained by subjecting an acid to an esterification reaction with a dihydric alcohol such as propylene glycol.

The preferred half-ester compound has the following general formula (A):
It can be shown as

General formula (A) R' 0 CH! -C-C-0-L-COOH However, in the general formula (A), L represents a divalent bonding group having 3 or more carbon atoms and having an ester bond in the molecular chain, and has a substituent. R1 represents a hydrogen atom or a methyl group.

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

General formula (1) %Formula% However, in General formula (1), Rx and Rs represent a hydrogen atom or a methyl group, m represents an integer of 1 to 14, and n represents O to
Represents an integer of 8.

General formula (2) However, in general formula (2), Ra and Rs represent a hydrogen atom or a methyl group, h represents an integer of 1 to 14, and X represents a hydrogen atom, a halogen group element, a lower alkyl group, an alkoxy represents a group.

General Formula (3) % Formula % However, in General Formula (3), R6 represents 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 general formula (4), R7 represents 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. represent.

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

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

The styrene monomer, acrylic ester monomer or methacrylic ester monomer, acrylic acid or methacrylic acid derivative having a hydroxyl group and Cica tC-
The vinyl polymer having a carboxy group obtained by polymerizing a half-ester compound obtained by an esterification reaction with a carbonic acid compound preferably has the above-mentioned styrene monomer as the content ratio of its monomer units. 30-95% heavy view
, particularly preferably 40 to 95% by weight, and preferably 70 to 5% by weight, particularly preferably 5 to 5% by weight of acrylic ester monomer or methacrylic ester monomer.
0% by weight, and the half ester compound preferably contains 0% by weight.
．． It is 5 to 30% by weight, particularly preferably 1 to 20% by weight.

When the content ratio of the acrylic ester monomer or methacrylic ester monomer exceeds 70% by weight, or when the content ratio of the half ester compound is 0.5% by weight.
If the amount is less than % by weight, offset resistance during high-temperature fixing may be reduced, and blocking resistance and plasticizer resistance may also be reduced.

In the present invention, the metal element of the polyvalent metal compound to be reacted with the carboxy group of the vinyl polymer having a carboxy group is Cu, Ag+Be.

Mg+ Ca+ S r+ B a, Z n, cd,
A L T l+ Ge, Sn, V+Cr, M
Examples include o+Mn+Fe, Ni, Co, Zr, and Se.

Among these various metal elements, alkaline earth metals (Be, Mg+Ca+Sr, Ba) and zinc group elements (Zn, Cd) are preferred, especially Mg and Z
n is preferred.

Examples of polyvalent metal compounds containing these metals include:
Fluorides, chlorides, chlorates, bromides, iodides, oxides, hydroxides, sulfides, sulfites, sulfates, selenides, tellurides, nitrides, nitrates, phosphides of the above metal elements, Examples include phosphinates, phosphates, carbonates, orthosilicates, acetates, chelates, and lower alkyl metal compounds such as methyl compounds or ethyl compounds. Among these, acetates of the above metal elements and oxides of the above metal elements are particularly preferred.

The amount of the polyvalent metal compound added cannot be unconditionally defined because it varies depending on the type and amount of monomers constituting the vinyl polymer having a carboxyl group, but for example, when the vinyl polymer is It is composed of the styrene monomer, the acrylic ester monomer or methacrylic 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, the amount is about 0.1 to 1 mol per 1 mol of the half-ester compound charged.

In order to react the polyvalent metal compound with the carboxyl group of the vinyl polymer having a carboxyl group, for example, the above-mentioned is added to a solution containing the vinyl polymer having a carboxyl group obtained by polymerization by a solution polymerization method. A polyvalent metal compound or a dispersion solution of the polyvalent metal compound is mixed, the temperature is raised, and the solvent is removed for about 1 to 3 hours. It is preferable to maintain this temperature for at least an hour to complete the reaction. In some cases, a polyvalent metal compound may be present in the reaction system together with a solvent before starting the polymerization of the vinyl polymer having a carboxy group, or the carboxy group obtained by removing the solvent may be The vinyl polymer having the above and the polyvalent metal compound may be melt-kneaded using a roll mill, kneader, extruder, etc. to react with each other.

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

In the present invention, as the specific core resin, one 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. 0 For example, by performing a first stage polymerization to obtain either a high molecular weight component or a low molecular weight component, one of the components thus obtained is added to a monomer composition to obtain the other component. By dissolving and performing the second stage polymerization, thereby producing the other component, it is possible to obtain a polymer having at least two maximum values in the molecular weight distribution curve. It is presumed that the polymer obtained by the two-stage polymerization is a mixture of a low molecular weight component and a 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 suspended tq polymerization method, an emulsion polymerization method, etc., and a solution polymerization method is particularly preferred.

Furthermore, a polymer having at least two maximum values in the molecular weight distribution curve can also be obtained by mixing a low molecular weight polymer component and a high molecular weight polymer component; may not be uniformly mixed at the molecular level, so it is preferable to carry out the above two-stage polymerization.

In the present invention, monomer units such as vinyl acetate, vinyl propionate, vinyl chloride, and ethylene may be contained in the molecular chain of the specific core resin to the extent that the properties are not impaired. A polymer or copolymer of monomers may be mixed in the core material particles, and other resins may be mixed as necessary in the core material particles. Examples of the resin include styrene-acrylic resin, polyurethane resin, and styrene-acrylic resin.
Examples include butadiene resin, polyester resin, and epoxy resin.

In the present invention, the surface of the core particle is covered with an outer shell made of a thermoplastic resin, and as such a thermoplastic resin, those conventionally used as resins for toners can be used. Specific examples include vinyl polymers, polyester resins, epoxy resins, and polyurethane resins. Among these, vinyl polymers and polyester resins are particularly preferred, and specific examples include styrene-n-butyl acrylate copolymer, styrene-methyl methacrylate-〇-butyl methacrylate copolymer, and terephthalic acid-bisphenol A.
Examples include propylene oxide condensates.

The thermoplastic resin forming the outer shell has a glass transition point Tg
It is preferable that the temperature is 50°C or higher. Glass transition point Tg
When is too small, the blocking resistance of the capsule toner may deteriorate.

In addition, the thermoplastic resin forming the outer shell has a ratio Mw/Mn of its weight average molecular weight and number average molecular weight Mn of 7.0.
If the value of this ratio Mw/Mn, which is preferably above, is too small, the offset resistance of the capsule toner may deteriorate.

The capsule toner of the present invention may optionally contain a colorant,
So-called toner components such as a charge control agent and an aid for improving fixing characteristics may be added, and these toner components may be contained in the core particles or contained in the outer shell. good.

Capsule toner also contains additives such as fluidity improvers, abrasives, and cleanability improvers, which are adhered to the outer shell or are held by being driven into the outer shell. Good too.

Examples of colorants include carbon bra, 7-di, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green offsalate, lamp black, rose bengal, a mixture of these,
Others can be mentioned.

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

Examples of the fixing property improving aid include polyolefins such as polyethylene and polypropylene. In particular, the softening point Tsp according to the ring and ball method is 70 to 150°C.
Polyolefins with a softening point T
Polyolefins having an sp of 120 to 150°C are preferred.

Inorganic fine particles can be preferably used as the fluidity improver and abrasive. The primary particle diameter of the inorganic fine particles is preferably 5u to 2n, particularly 51μ to 5n.
00M is preferable.

In addition, the specific surface area according to the BET method is 20 to 500 m"
/g is preferable. The proportion of the inorganic fine particles used is preferably 0.01 to 5% by weight, particularly preferably 0.01 to 2.0% by weight of the capsule toner. Specific examples of inorganic fine particles include silica,
Alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, red iron oxide, antimony trioxide, Magnesium oxide, zirconium oxide,
Examples include barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

Particularly preferred is fine silica powder.

The silica fine powder is a fine powder having a 5i-0-St bond, and may be produced by either a dry method or a wet method.In addition to anhydrous silicon dioxide, aluminum silicate, It may be any of sodium silicate, potassium silicate, magnesium silicate, zinc silicate, etc., but preferably contains 85 or more SiO□.Specific examples of fine silica powder include various commercially available products. However, those having a hydrophobic group on the surface of the fine particles are particularly preferable, such as "Aerosil R-972J,""AerosilR-974J,""AerosilR-805J,""Aerosil R-812J (manufactured by Aerosil Co., Ltd.)," [
Taranox 500J (manufactured by Talco) and the like can be preferably used. In addition to these, fine silica powder surface-treated with a silane coupling agent, a titanium coupling agent, a silicone oil, a silicone oil having an amine in its side chain, etc. can be used.

Examples of the cleaning performance 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, in the case of producing a magnetic toner, fine particles of magnetic material may be contained in one or both of the core material particles and the outer shell.

Such magnetic materials include ferrite, magnetite, iron, nickel, cobalt, and other ferromagnetic metals or alloys, compounds containing these elements, and compounds that do not contain ferromagnetic elements but can be treated with appropriate heat treatment. Mention may be made of alloys which become ferromagnetic, such as alloys of the type called Heusler alloys containing manganese and copper, such as manganese-copper-aluminum, manganese-copper-SR1, chromium dioxide, and others. The magnetic material is preferably contained in a uniformly dispersed form in the form of a fine powder with an average particle size of 0.1" ljIm, and the content ratio of the magnetic material is 10 parts by weight per 100 parts by weight of the capsule toner. ~
It is preferably 70 parts by weight, particularly preferably 20 to 50 parts by weight.

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

(1) The specific core material resin for forming the core material particles and toner components such as colorants used as necessary,
For example, the material is melt-kneaded using an extruder, cooled, pulverized using a jet mill, etc., and then classified to obtain core material particles of a desired particle size.

(2) The specific core material resin for forming the core material particles and toner components such as colorants used as necessary,
For example, a method of obtaining core material particles of a desired particle size by melting and kneading with an extruder and spraying the molten state with a spray dryer or the like.

(3) The specific core material resin for forming the core material particles and toner components such as colorants used as necessary,
For example, a method of obtaining core material particles of a desired particle size by melt-kneading using an extruder and dispersing this in a liquid in a molten state.

In addition, in the present invention, as a method for providing an outer shell on the surface of the core material particles, a coating solution in which a thermoplastic resin for forming the outer shell is dissolved in a solvent is used, for example, by dipping, spray drying, fluidization, etc. A method can be used in which a coating layer is formed by coating the surface of core material particles by a method such as a bed method, heating and drying to volatilize the solvent, and curing the coating layer during or after drying. For example, when forming a coating layer by a fluidized bed method, the core particles are raised to an equilibrium height by a rising pressurized gas flow in a fluidized bed device, and then the core particles fall again. The coating solution can be sprayed and this spraying can be repeated to form the shell.

The capsule toner of the present invention may be combined with a carrier to form a two-component developer, or may be used as a magnetic capsule toner containing a magnetic substance to form a one-component developer consisting only of the magnetic capsule toner. It may be something that does.

The capsule toner of the present invention is a capsule toner for heat roller fixation, and is used to form an image, for example, in the following manner. That is, in electrophotography, an electrostatic latent image formed on a photoreceptor, which is a latent image carrier, is developed with a two-component developer or a one-component developer configured using the capsule toner of the present invention, The obtained toner image is electrostatically transferred, for example, to a support made of paper or the like, and then the transferred toner is fixed by a hot roller fixing method, thereby forming 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 placed in opposition to the heat roller, and a heat source. placed opposite each other. While maintaining the temperature of the heat roller within a certain range using a heating source, the toner is brought into direct contact with the heat roller by passing the toner-transferred support between the heat roller and the pressure roller. is heat-fixed to the support.

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

[Specific examples]

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) 50 g of toluene was placed in a separable flask with a capacity of 31 g equipped with a thermometer, a stirrer, a nitrogen gas inlet pipe, and a flowing condenser.
After introducing nitrogen gas through a nitrogen gas introduction tube to create an inert cloud atmosphere inside the flask, the flask was heated in an oil bath to reach the reflux temperature of toluene.

Next, 200 g of styrene, 8 g of n-butyl acrylate
A composition of high molecular weight components consisting of 0 g of methyl methacrylate, 20 g of methyl methacrylate, and 0.9 g of benzoyl peroxide was placed in a flask and reacted for 14 hours while being maintained at reflux temperature to form a high molecular weight polymer.

Next, 382 g of styrene, 35 g of α-methylstyrene,
A polymerization reaction was carried out while gradually dropping a composition of low molecular weight components consisting of 210 g of n-butyl acrylate, 73 g of monoacryloyloxyethyl succinate, 42 g of benzoyl peroxide, and after the dropping of the composition of low molecular weight components was completed. A low molecular weight polymer was formed by further carrying out a polymerization reaction for 4 hours.

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

After the reaction, the solvent toluene was distilled off under reduced pressure.
A resin formed by reacting a carboxy group of a low molecular weight component with a polyvalent metal compound was obtained. This will be referred to as "Resin A".

This resin A has a molecular weight distribution curve of 7.5× by gel permeation chromatography (HLC-802UR, GMH6 column, manufactured by Toyo Soda Co., Ltd.).
It has maximum values at 103 and 2.8 X 10', respectively, the weight average molecule fiMi+ is 1.2 X 10', and the ratio M
-/Mn value is 17.1, and glass transition point Tg is 46°C.

<Production of resin B> (for the present invention) In the production of resin A, as a composition of high molecular weight components,
140g styrene, 80g n-butyl acrylate, n
- Using a composition of high molecular weight components consisting of 60 g of butyl methacrylate, 20 g of methyl methacrylate, and 1.5 g of azobisisobutyronitrile, and as a composition of low molecular weight components, 337 g of styrene, 70 g of α-methylstyrene,
2-Ethylhexyl acrylate 210g1 Methyl methacrylate 35g1 Monoacryloyloxyethyl isophthalate 48g1 Benzoyl peroxide 35g
Resin A was used except that 22.4 g of zinc acetate was used as the polyvalent metal compound.
In the same manner as in the production of , a resin was obtained by reacting a carboxy group of a low molecular weight component with a polyvalent metal compound. This will be referred to as "Resin B".

This resin B has a molecular weight distribution curve of 1.2 x 1 by gel permeation chromatography.
It has maximum values at 0' and 2.4X10', weight average molecular weight M- is 1.15XIO', ratio Mw/
The Mn value is 9.5 and the glass transition point Tg is 48°C.

Production of Resin A> (For Comparison) A comparative resin was obtained in the same manner as in the production of Resin A, except that zinc oxide, which is a polyvalent metal compound, was not used. This will be referred to as "resin a".

This resin a has a molecular weight distribution curve of 7, l×103 by gel permeation chromatography.
The weight average molecular weight is 1.18X10', the ratio Mw/Mn is 18.1, and the glass transition point Tg is 43°C.

<Example 1> (1) Production of core material particles 100 parts by weight of the above resin A, 10 parts by weight of carbon blank [Mogull LJ (manufactured by CABOFT), and polypropylene [Viscol 660PJ C'lX point T]
sp: 130°C, manufactured by Sanyo Chemical Industries, Ltd.) in a type blender, melt-kneaded with two rolls, cooled, coarsely crushed with a hammer mill, and further finely crushed with a shared mill. The particles were classified using an air classifier to obtain core particles having a particle size of 1 to 30x. This is referred to as "core material particle 1."

(2) Production of outer shell Styrene-methyl methacrylate-acrylic acid-n-butyl acrylate copolymer (copolymerization weight ratio -65 to 15
:5 :15) emulsified dispersion (solid content: 10% by weight) 5
After adding 300 parts by weight of the core material particles 1 to 00 parts by weight and sufficiently dispersing them, spray drying was performed at an inlet temperature of 180°C and an outlet temperature of 60°C to coat the surface of the core material particles with the above copolymer. A capsule toner powder was obtained.

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

(3) Preparation of developer 950 of a resin-coated carrier prepared by coating the surface of copper-zinc ferrite particles with a styrene-methyl methacrylate copolymer (copolymerization weight ratio -70:30) to the above weight part of toner 1. A developer was prepared by mixing parts by weight. This will be referred to as "Developer 1".

(4) Actual photocopying test Using the above developer 1, the electrophotographic copying machine "U-Bix"
1600J (manufactured by Konishiroku Photo Industry Co., Ltd.) to form and develop an electrostatic latent image, and conduct a live copying test in which the resulting toner image was transferred onto transfer paper and fixed by a heated roller fixing device to form a copy image. The following items were evaluated.

■Minimum fixing temperature After creating an unfixed image using the above copying machine, a heat roller with a diameter of 30φ whose surface layer is made of Teflon (polytetrafluoroethylene manufactured by DuPont) and a silicone rubber surface layer rKE-1300RTVj (Shin-Etsu Chemical Co., Ltd.) are used. A toner image made of the sample toner was transferred onto a 64 g/ll'' transfer paper using a heat roller fixing device consisting of a pressure roller (manufactured by Kogyo Co., Ltd.) at a linear speed of 7011 Il/sec of the heat roller.
The fixing operation was performed with a linear pressure of 0.8 kg/cm and a nip width of 4.9 mm, and the temperature of the heat roller was set at 100 to 240°C.
Raise the temperature step by step by 5℃ within the range of 5℃ and repeat at each temperature, apply Kimwipe rubbing to the formed fixed image, and reach the lowest setting temperature for the fixed image that shows sufficient rubbing resistance. Temperature. Note that the heat roller fixing device used here does not have a silicone oil supply mechanism. In addition, the environmental conditions were normal temperature and pressure (temperature 20℃,
60% relative humidity) and low temperature and low humidity (temperature 10°C).

The relative humidity was 40%).

■Offset occurrence temperature Offset occurrence temperature is measured in accordance with the above minimum fixing temperature measurement, but after creating an unfixed image with the above copier,
The toner image is transferred and fixed using the heat roller fixing device described above, and then a blank transfer paper is sent to the heat roller fixing device under the same conditions and visually observed to see if toner stains occur on it. The operation was repeated while the set temperature of the heat roller of the heat roller fixing device was successively increased, and the lowest set temperature at which toner staining occurred was taken as the offset occurrence temperature. In addition, the environmental conditions are normal temperature and normal pressure (temperature 20
℃, relative humidity 60%) and low temperature and low humidity (temperature 10℃, relative humidity 40%).

(2) 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 test was conducted at a temperature of 55℃ and a relative humidity of 6.
The toner was left under 0% environmental conditions for one day and judged based on whether or not agglomerates were formed in the toner. If no agglomerates were observed, it was marked "○", and if agglomerates were observed, it was marked "x". And so.

■Environmental conditions are low temperature and low humidity (temperature 10℃, relative humidity 40%)
Durability of the fuser under low temperature and low humidity (temperature 10°C, relative humidity 40%), electrophotographic copying e! r U-Bix 160
Set the temperature of the QJ's fuser to 1 higher than the minimum fixing temperature above.
We conducted many live-action tests with the temperature set to 0°C higher, and found that the heat roller was dirty, the cleaning roller for the heat roller was dirty, the pressure roller was dirty, offset occurred, jamming occurred, and the back side of the transfer paper was dirty. The durability of the fixing device was evaluated.

■Capri “Sakura Densitometer” (manufactured by Konishiroku Photo Industry Co., Ltd.)
The determination was made by measuring the relative density of a white background portion with a document density of 0.0 with respect to the developed image. Note that the white background reflection density was set to 0.0. For evaluation, if the relative concentration is less than 0.01, it is marked as "○", and if it is 0.01 or more and less than 0.03, it is marked as "○".
Δ", and cases of 0.03 or more were marked "x".

0 Image Quality A photocopying test was conducted continuously for 30,000 times using the above-mentioned copying machine, and the sharpness of the copied image was examined at the initial stage of image formation and after 30,000 times. The evaluation is ``○'' if it is good, and ``Δ'' if it is not good but still at a practical level.
Items that are inferior and have problems in practical use are marked with an "x".

■Cleanability A live copying test was conducted 30,000 times using the above-mentioned copying machine, and each time the number of copies reached s, ooo times, the surface of the photoreceptor was visually observed after being cleaned by the cleaning blade. Judgment was made based on the presence or absence of deposits. The evaluation was rated "○" if it was good, "Δ" if it was not good but still at a practical level, and "x" if it was inferior and had problems in practical use.

■ Filming resistance After carrying out 30,000 continuous tests using the copying machine mentioned above, the surface of the carrier particles, the surface of the photoreceptor, and the cleaning blade were each observed using an electron microscope or visually, and the presence or absence of adhesion was determined by I judged it. When no deposits were observed, it was marked as "○", when some deposits were observed, it was marked as "Δ", and when a considerable amount of deposits were observed, it was marked as "x".

The above results are shown in Table 1 below.

<Example 2> (1) Production of core material particles 100 parts by weight of the above resin B, 1 part of carbon black "Mogull LJ (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 particles.These are referred to as "core particles 2."

(2) Production of outer shell Capsule toner powder was obtained in the same manner as in Example 1, except that the core particles 2 described above 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 will be referred to as "toner 2".

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

(4) Actual photography test Using the developer 2 described above, an actual photography 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 Core Particles 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, a photographic 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 comparative resin a and carbon black
10 parts by weight of Mogul LJ (manufactured by Caboft) was treated in the same manner as in Example 1 to obtain core material particles for comparison.

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

) was obtained.

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

As understood from the results in Table 1, toner 1 of the present invention
and 2, both have excellent low-temperature fixing properties, particularly sufficient low-temperature fixing properties even under low-temperature, low-humidity environmental conditions, and have excellent anti-offset properties within the fixable temperature range. has a wide range of 75 to 80°C. In addition, the anti-blocking property is good, and even after 30,000 times of live copying tests, clear copied images without fogging can be obtained.
Furthermore, the cleaning properties and filming resistance are also good. Further, even under low temperature and low humidity environmental conditions, the thermal roller is less contaminated and troubles such as clogging occur, and the image forming process can be carried out smoothly.

On the other hand, Comparative Toner 1 does not have an outer shell, so it has sufficient low-temperature fixing properties, but its anti-blocking properties are poor, resulting in poor triboelectric charging properties with the carrier. The copied image becomes foggy and unclear. In addition, the cleaning properties and filming resistance are poor, and the durability is low. Further, under environmental conditions of low temperature and low humidity, the heat roller becomes extremely dirty, which causes clogging, making it difficult to perform the image forming process smoothly.

In addition, in Comparative Toner 2, the comparative resin a constituting the core material particles was not crosslinked with a polyvalent metal compound, so the offset resistance was low and the heat roller was significantly stained. Problems such as jamming are likely to occur early on. In addition, after 30,000 live-action tests, fogging occurs and the image becomes unclear.
It has low durability.

Claims (1)

[Scope of Claims] 1) A capsule toner for hot roller fixing comprising meltable core particles and an outer shell made of a thermoplastic resin provided to cover the surface of the core particles, comprising: 1. A capsule toner for heat roller fixing, wherein the material particles contain a core resin obtained by reacting a polyvalent metal compound with a carboxyl group of a vinyl polymer having a carboxyl group. 2) Claim 1, wherein the core resin contains a low molecular weight component and a high molecular weight component, and has at least two maximum values in a molecular weight distribution curve determined by gel permeation chromatography. Capsule toner for heat roller fixing as described in . 3) Low molecular weight components have a maximum value of 1 in the molecular weight distribution curve determined by gel permeation chromatography.
,000 to 20,000, and the high molecular weight component has a maximum value of 100,000 in the molecular weight distribution curve.
3. The capsule toner for heat roller fixing according to claim 2, wherein the toner has a particle size in the range of 0 to 2,000,000. 4) The core material resin has a ratio Mw/Mn of its weight average molecular weight Mw to number average molecular weight Mn of 3.5 or more. The capsule toner for heat roller fixing according to any one of the above. 5) The capsule toner for hot roller fixing according to any one of claims 1 to 4, wherein the core resin has a glass transition point Tg of 40 to 70°C. 6) The capsule toner for hot roller fixing according to any one of claims 1 to 5, wherein the proportion of the core resin in the meltable core particles is 50% by weight or more. 7) Claim 1, characterized in that the thermoplastic resin forming the outer shell has a glass transition point Tg of 50°C or higher.
The capsule toner for hot roller fixing according to any one of items 6 to 6.