JP2511698B2 - Binder for toner - Google Patents

Description

TECHNICAL FIELD The present invention relates to a binder for toner. More specifically, it relates to a binder for electrophotographic toner.

[Prior Art] Conventionally, as a binder for an electrophotographic toner, there is one in which polyester and vinyl resin are mechanically mixed (for example, JP-A-49-6931 and JP-A-54-114245). There is also one in which polyester and vinyl polymer are chemically bonded (for example, JP-A-56-116043).

[Problems to be Solved by the Invention] However, the compatibility between polyester and vinyl resin is poor, and in the system according to the former technique, a heterogeneous dispersion state results and a sea-island structure is formed. This state is not improved by operations such as melt-kneading for toner formation, and the average particle size of the island component is equal to or exceeds the average particle size of the toner, so that the deterioration of image characteristics due to uneven charging of the toner, for example, There is a problem of image instability due to a decrease in image density, occurrence of fogging, image instability during long-term use, and environmental changes such as temperature and humidity. Further, in the system based on the latter technique, the polyester and the vinyl polymer are strongly cross-linked, and sufficient fixing property as a toner binder cannot be obtained.

[Means for Solving Problems] The present inventors have arrived at the present invention as a result of earnestly studying the development of a binder for an electrophotographic toner having both the characteristics of polyester and vinyl polymer which do not have the above problems.

That is, the present invention provides a toner binder comprising a polyester and a vinyl polymer, wherein the binder copolymerizes vinyl monomer (C) and polyester (A) copolymerizable with (C) in polyester (B). And a toner binder comprising a polyester and a vinyl polymer, wherein the binder is a polyester (B) and a vinyl polymer (D), and a vinyl monomer (C) and A binder for a toner, which is a uniform dispersion obtained by copolymerizing (C) with a copolymerizable polyester (A).

As the polyester (B) in the present invention, a saturated polyester, for example, a polyester produced by polycondensing a polyhydric alcohol and a polybasic acid can be used.

Examples of the polyhydric alcohol include (1) ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol,
1,4-butanediol, neopentyl glycol, 1,6-
Saturated aliphatic glycols such as hexanediol and their alkylene oxides [ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as PO)] adducts; (2) hydroquinone, catechol, resorcin, pyrogallol, bisphenols (Bisphenol A, bisphenol F, bisphenol sulfone, etc.) and hydrogenated bisphenols to which alkylene oxide (EO and / or PO) is added are phenolic glycols; (3) glycerin, trimethylolpropane, trimethylolethane, hexanetriol , Pentaerythritol, diglycerin, α-methylglucoside, sorbitol, xylit, mannitol, glucose, fructose, sucrose and other saturated aliphatic alcohols of 3 to 8 valences And their alkylene oxide adducts; (4) alkanolamines (triethanolamine, tripropanolamine, etc.), alkylenediamines (having 2 to 6 carbon atoms such as ethylenediamine, hexamethylenediamine, etc.), polyalkylenepolyamines (carbons of alkylene). Numbers 2 to 6 such as diethylenetriamine and triethylenetetraamine), aromatic amines (aniline, phenylenediamine, diaminotoluene, xylylenediamine, methylenedianiline, diethyltolylenediamine, diphenyletherdiamine),
Alicyclic amines (isophoronediamine, cyclohexylmethanediamine, cyclohexylenediamine, etc.), heterocyclic amines (piperazine, aminoethylpiperazine, other substances described in Japanese Patent Publication No. 55-21044, etc.), etc., and alkylene oxides (EO and / Or a PO) -added amino group-containing polyhydric alcohol; and a mixture of two or more thereof.

Among these, preferred are ethylene glycol,
Neopentyl glycol and bisphenols (particularly bisphenol A) to which alkylene oxide (EO and / or PO) is added in an amount of 2 to 3 moles and mixtures thereof, particularly preferably 2 to 3 moles of alkylene oxide of bisphenol A. Those added, neopentyl glycol and mixtures of two or more of these.

Examples of polybasic acids are (1) saturated aliphatic dibasic acids such as malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, octylsuccinic acid, and cyclohexanedicarboxylic acid, and aromatics such as phthalic acid, isophthalic acid, and terephthalic acid. Group dibasic acids; (2) trimellitic acid, 1,2,4-cyclohexanedicarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid Acid, pyromellitic acid, benzophenonetetracarboxylic acid, tetra (methylenecarboxyl) methane, 1,2,7,8
Trivalent or higher polybasic acids such as octane tetracarboxylic acid; and anhydrides and lower alkyl esters of these acids can also be used.

Among these, alkyl (C 4-18) succinic acids represented by succinic acid, phthalic acid, isophthalic acid, terephthalic acid and octyl succinic acid are preferable.

The polyester (B) according to the present invention is preferably a linear type, but is not limited to trimethylolpropane and the like.
A branched type obtained by using a trivalent or higher polybasic acid such as a trivalent or higher alcohol and / or trimellitic acid can also be used. The amount of trihydric or higher alcohols and polybasic acids is usually 30 in polyhydric alcohols and polybasic acids.
It is at most mol%, preferably at most 10 mol%.

Further, an amide bond-containing polyester produced by using a small amount of polyamines such as hexamethylenediamine and methylenediamine in addition to the polyhydric alcohol and the polybasic acid can also be used as the polyester (B) according to the present invention. .

In the condensation reaction between the polyhydric alcohol and the polybasic acid, the molar ratio of the polyhydric alcohol and the polybasic acid is usually 1.0: 1.3 to 1.0: 0.7 in the case of the dihydric alcohol and the dibasic acid.
And preferably 1.0: 1.2 to 1.0: 0.8.

The reaction may optionally be carried out by an esterification catalyst (eg zinc oxide,
Stannous oxide, dibutyltin oxide, dibutyltin dilaurate, etc.), usually at any temperature of 150 to 250 ° C. The reaction can be carried out under normal pressure or reduced pressure, and in the presence or absence of an inert gas or a solvent (eg toluene, xylene etc.).

The sum of the acid value and the hydroxyl value of the polyester is usually 100 or less, preferably 60 or less.

The polyester [polyester (A)] copolymerizable with the vinyl monomer in the present invention can be obtained by introducing a functional group having a copolymerizability with the vinyl monomer into the hydroxyl group or carboxylic acid group located at the terminal of the saturated polyester. .

In order to introduce a functional group having copolymerizability with a vinyl monomer into the hydroxyl group or carboxylic acid group of polyester, a compound having both a group having reactivity with the hydroxyl group or carboxylic acid group and a group having vinyl polymerizability (a ) And polyester. Examples of the group reactive with the carboxylic acid group include an epoxy group, a hydroxyl group and an amino group. Examples of the group reactive with a hydroxyl group include an acid anhydride group.

Further, as the vinyl polymerizable group, an α, β-unsaturated group is preferable.

As the compound (a) having both of them, a (meth) acrylic compound having a hydroxyl group [means an acrylic compound and / or a methacrylic compound. Hereinafter, this expression will be used] [eg, hydroxyethyl (meth) acrylate, etc.], (meth) acrylic compound having an amino group [eg, aminoethyl (meth) acrylate, aminoethyl (meth) acrylamide, etc.], having an epoxy group Examples thereof include (meth) acrylic compounds [eg, glycidyl (meth) acrylate] and compounds having an anhydride group [eg, maleic anhydride, (meth) acrylic anhydride, etc.]. Of these, preferred are maleic anhydride and glycidyl (meth) from the viewpoint of reactivity.
It is an acrylate. As the saturated polyester to be reacted with the compound (a), those having the same composition as that described in the section of the polyester having no reactivity can be used. When the compound (a) reacts with the carboxyl group of polyester, the acid value is 90 to 10 and the hydroxyl value is 10 or less, particularly preferably 70 to 20 and 5 or less. When the compound (a) that reacts with the hydroxyl group of polyester is used, the hydroxyl value is 90 to 10, the acid value is 10 or less, and particularly preferably 70 to 20.
And 5 or less.

Obtained by polycondensing a polyhydric alcohol and a polybasic acid to bring the hydroxyl value and acid value of the polyester into this range, and then adding the compound (a) and, if necessary, adding a solvent and / or a catalyst to react. . The input amount of the compound (a) can be calculated from the molecular weight of the polyester calculated from the acid value and the hydroxyl value and the molecular weight of the compound (a).

The saturated polyester (B) and the polyester (A) having a copolymerizability with a vinyl monomer can be separately prepared and used, but after the polyester (B) is prepared, a predetermined amount of the compound (a) is reacted. The method of obtaining the mixture of (A) and (B) is preferable from the viewpoint of simplifying the manufacturing process.

In this reaction, the production ratio of the polyester (B) and the polyester (A) can be determined by tracing the hydroxyl value of the reaction system when (a) reacts with the hydroxyl group of the polyester (B), and when reacting with the acid group. It is calculated from the following formula by tracing the acid value.

When compound (a) reacts with a hydroxyl group OHV ₀ : hydroxyl value of system before reaction OHV: hydroxyl value of system after reaction When compound (a) reacts with acid group AV ₀ : Acid value of the system before the reaction AV: Acid value of the system after the reaction The weight of the polyester (A) in the whole polymer is usually 1 to 20%, preferably 2 to 16%. If the weight of the polyester (A) is less than 1%, a sufficient graft product with the vinyl polymer cannot be obtained, and a uniform dispersion of the vinyl polymer and the polyester cannot be obtained. On the other hand, if it exceeds 20%, the lower limit temperature of toner fixing (hereinafter abbreviated as MF) becomes high.

Examples of the vinyl monomer (C) to be polymerized in the presence of the polyester (B) include a styrene-based monomer, a (meth) acrylic-based monomer and other monomers.
Styrene as a styrene monomer, alkyl styrene (for example, α-methyl styrene, p-methyl styrene)
And the like, and styrene is preferable. Examples of the (meth) acrylic monomer include alkyl (meth) acrylates [alkyl having 1 to 18 carbon atoms, for example, methyl (meth) acrylate, ethyl (meth) acrylate,
Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, etc.], hydroxyl group-containing (meth) acrylate [hydroxyl ethyl (meth) acrylate, etc.], amino group-containing (meth ) Acrylate [dimethylaminoethyl (meth) acrylate,
Diethylaminoethyl (meth) acrylate and the like], nitrile group-containing (meth) acrylic compounds (such as acrylonitrile) and (meth) acrylic acid. Of these, alkyl (meth) acrylate is preferable, and methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and a mixture of two or more thereof are particularly preferable. Is. Examples of other monomers include vinyl esters (for example, vinyl acetate and vinyl propionate) and aliphatic hydrocarbon vinyl monomers (for example, butadiene).

A polyfunctional monomer having at least two polymerizable double bonds in order to obtain a higher molecular weight polymer upon polymerization [eg di- or polyvinyl compound (divinylbenzene, divinyltoluene, ethylene glycol diacrylate, 1,6-hexamethylene glycol di- Acrylate etc.)] can be added. Preferred are divinylbenzene and 1,6-hexamethylene diacrylate.

The amount (% by weight) of each vinyl monomer in these total vinyl monomers (C) is as follows. The styrene monomer content is usually 50 to 95%, preferably 60 to 90%. The (meth) acrylic monomer is usually 50 to 5%, preferably 40 to 10%. Other monomers such as vinyl ester and aliphatic hydrocarbon monomers are usually 10% or less, preferably 5% or less. The polyfunctional monomer content is usually 5% or less, preferably 3% or less.

If the amount of styrene-based monomer exceeds 95% and the amount of (meth) acrylic-based monomer is less than 5%, the MF of the toner becomes high. Conversely, if the amount of each is less than 50% or more than 50%, the toner heat rolls. The temperature at which the offset occurs (hereinafter abbreviated as HO) becomes low and the blocking resistance also decreases. If the amount of the other monomer exceeds 10%, the blocking resistance of the toner is deteriorated. When the amount of the polyfunctional monomer exceeds 5%, gelation occurs during the polymerization.

The weight ratio of the vinyl monomer (C) to the total polymer is usually 30 to 70%, preferably 35 to 65%. If it exceeds 70%, the fixing property is deteriorated. Further, if it is less than 30%, the environmental dependency of the toner charge amount becomes large.

Examples of the vinyl polymer (D) include the vinyl monomer polymers described in the preceding section. The constituent monomers of the vinyl monomer and the constituent ratio thereof are the same as those described in the section of the vinyl monomer, and the preferable ones are also the same. Polymerization is usually carried out by radical polymerization or radiation polymerization,
It can be carried out by a solution polymerization method, a suspension polymerization method or an emulsion polymerization method. The solution polymerization method is preferred. The weight average molecular weight is preferably 50,000 to 1,000,000. 50,00
If it is less than 0, the glass transition point (Tg) of the binder is lowered and the blocking resistance of the toner is deteriorated. If it exceeds 1,000,000, the MF of the toner is increased. The molecular weight is determined by gel permeation chromatography (hereinafter abbreviated as GPC) using polystyrene (hereinafter abbreviated as THF) as a solvent in terms of polystyrene.

The vinyl polymer (D) can be added to the system after the reaction between the polyester and the vinyl monomer, but in order to obtain a more uniform dispersion of the vinyl polymer and the polyester, it is preferable to add the vinyl polymer during the reaction between the polyester and the vinyl monomer. . The weight ratio of the vinyl polymer (D) to the total polymer, together with the amount of the vinyl monomer (C), is usually 30 to 70%, preferably 35 to 65%.

Radical polymerization of the vinyl monomer (C) and the polyester (A) copolymerizable therewith in the presence of the polyester (B) is usually carried out by solution polymerization. As the solvent, aromatic hydrocarbon solvents (toluene, xylene, etc.), chlorine solvents (chloroform, carbon tetrachloride, ethylene dichloride,
Ethylene tetrachloride) and mixed solvents of two or more of these. Although the amount of the solvent used is not particularly limited, it is usually 400% or less based on the total weight of the components other than the solvent in view of production efficiency.

A polymerization initiator is usually used for the polymerization, and as the polymerization initiator, an azo-based initiator (azobisisobutyronitrile, azobisisovaleronitrile, etc.), a peroxide-based initiator (benzoylperoxide, lauroyl) is used. Peroxide, di-tert.-butyl peroxide, tert.-butylcumyl peroxide, dicumyl peroxide,
tert.-Butylperoxybenzoate, 1,1-bis (te
rt.-butylperoxy) 3,3,5-trimethylcyclohexane and the like).

The polymerization reaction is usually performed in an atmosphere of an inert gas such as nitrogen. Polymerization temperature is usually 50 ~ 200 ℃, preferably 70 ~ 150
° C. If the temperature is lower than 50 ° C., (A), (B) and (D) will not dissolve, resulting in insufficient dispersion, and if it exceeds 200 ° C., the polymer may decompose. While the reaction time depends on other conditions, it is generally 1 to 50 hours, preferably 2 to 10 hours. If the reaction time is shorter than 1 hour, it is often difficult to control the reaction, and if it exceeds 50 hours, it is economically disadvantageous. When a solvent is used during the polymerization, the solvent is removed after the reaction. Desolvation is performed under normal pressure or reduced pressure.

In the present invention, a low molecular weight polyolefin can be used in addition to the above constituents. The low molecular weight polyolefin has a weight average molecular weight of usually 1,000 to 100,000, preferably 5,000 to 60,000 (a): polyethylene, polypropylene, ethylene-α
Olefin (C3-8) copolymer (eg ethylene
50 wt% or more, especially 70 wt% or more), (b): a) maleic acid derivative (maleic anhydride, maleic acid dimethyl ester, maleic acid diethyl ester, maleic acid di-2-ethylhexyl ester, etc.)
Adduct, (C): Oxide of (A), (D): Ethylenically unsaturated carboxylic acid ((meth) acrylic acid, itaconic acid, etc.) and / or its ester (alkyl (C ₁ -C ₁₈ ) ester) Etc.) and an ethylenically unsaturated hydrocarbon (ethylene, propylene, butene-1 etc.) and a mixture of two or more kinds thereof.

Among the above low molecular weight polyolefins, (a) is obtained by thermally degrading (pyrolyzing) a high molecular weight polyolefin (molecular weight is usually 10,000 to 2,000,000), or by homopolymerizing or copolymerizing an olefin. (B) is obtained by subjecting a low molecular weight polyolefin and a maleic acid derivative to an addition reaction in the presence or absence of a peroxide catalyst. (C) can be obtained by a method of oxidizing a low molecular weight polyolefin with oxygen or an oxygen-containing gas (air) or a method of oxidizing ozone with an oxygen-containing gas or an ozone-containing gas (air). The acid value of the oxide is usually 100 or less, preferably 50 or less. (D) is obtained by copolymerizing an ethylenically unsaturated carboxylic acid and / or its alkyl ester (C _{1 to} C ₁₈ ) with an ethylenically unsaturated hydrocarbon. The amount of ethylenically unsaturated carboxylic acid and / or its alkyl ester is usually 30% or less, preferably 20% or less on a weight basis.

The molecular weight of low molecular weight polyolefin is determined by GPC,
It is measured at 135 ° C. using o-dichlorobenzene as a solvent.

Although a low molecular weight polyolefin can be blended after the binder is manufactured, it is more preferable that the low molecular weight polyolefin is uniformly dispersed in the electrophotographic toner which is an application of the present binder because a better releasing effect can be obtained. It is preferable to add a low molecular weight polyolefin to the system during the polymerization of vinyl monomer.

The amount of low molecular weight polyolefin is usually 30% by weight or less, preferably 20% by weight or less, based on the total weight of the dispersion of the present invention. If it exceeds 30% by weight, the dispersion will be sufficient.

In the dispersion of the present invention obtained by copolymerization, usually more than 50% of the components have a sea structure, and less than 50% of the components have an island structure, based on the weight of the constituents. A simple blend of polyester and vinyl polymer often has an average particle size of the island component of 20 μ or more, but a dispersion state of 2 μ or less can be obtained by using the method of the present invention. The minimum amount component in the constituent components is dispersed in the other component having the closest solubility parameter, and the low molecular weight polyolefin which is the minimum amount component used in the binder of the present invention is usually dispersed in the vinyl resin. ing.

The binder of the present invention is usually white to brown solid and has a glass transition point of usually 40 to 80 ° C, preferably 45 to 70 ° C for electrophotographic toner. If the glass transition point is less than 40 ° C, the storage stability of the toner becomes poor, and if it exceeds 80 ° C, the MF becomes high and it is difficult to use as a toner.

The electrophotographic toner used as the binder of the present invention is
Toner binder is usually 50 to 50% based on the weight of toner.
95%, known coloring materials (carbon black, iron black, benzidine yellow, quinacridone, rhodamine B, phthalocyanine, etc.) usually 5-10% and magnetic powder (ferromagnetic metal powder such as iron, cobalt, nickel or magnetite, Compounds such as hematite and ferrite) are usually used in an amount of 0 to 50%.

Further, various additives such as lubricants (polytetrafluoroethylene, low molecular weight polyolefin, fatty acids, or metal salts or amides thereof, etc.) and charge control agents (nigrosine, quaternary ammonium salts, etc.) and the like can be included. The amount of these additives is usually 0 to 5% based on the weight of the toner.
Is.

The electrophotographic toner is dry-blended with the above components, melt-kneaded, then coarsely pulverized, and finally atomized using a jet pulverizer or the like, and then further classified to obtain fine particles having a particle size of 5 to 20μ. Obtained as.

The electrophotographic toner is used as a developer for an electric latent image by being mixed with carrier particles such as iron powder, glass beads, nickel powder, and ferrite as needed. Further, hydrophobic colloidal silica fine powder can be used to improve the fluidity of the powder.

The electrophotographic toner is used after being fixed on a support (paper, polyester film, etc.). As a fixing method, a known hot roll fixing method can be applied.

[Examples] The present invention will be further described below with reference to Examples, but the present invention is not limited thereto.

 The molecular weight measurement by GPC was performed under the following conditions.

Equipment: Toyo Soda HLC-802A column: TSK gel GMH6 2 pieces (Toyo Soda) Measurement temperature: 25 ° C Sample solution: 0.5 wt% THF solution Injection volume: 200 μl Detector: Refractive index detector Molecular weight calibration curve Was prepared using standard polystyrene.

Synthesis Example 1 Styrene 720 parts, 2-ethylhexyl acrylate 190
Part, 90 parts of methyl methacrylate and 6.5 parts of divinylbenzene [(solution 1-1)], 8.5 parts of azobisisobutyronitrile and 250 parts of toluene [(solution 1-2)] A solution of 2 parts of azobisisobutyronitrile and 55 parts of toluene was prepared [(Solution 1-3)]. 250 parts of toluene was charged in a reactor equipped with a thermometer, a stirrer, a gas introduction tube, a dropping funnel and a cooling tube. The system was purged with nitrogen and then kept under a nitrogen atmosphere. While stirring, the temperature was raised with heating, and while toluene was refluxed, (solution 1-1) and (solution 1-2) were added dropwise over 4 hours, and then 2
Reflux for hours. Thereafter, (solution 1-3) was added twice every hour to complete the polymerization. The solvent was distilled off and the glass transition point was 61.
A vinyl polymer having a number average molecular weight of 11,000 and a weight average molecular weight of 300,000 was obtained at ℃. This polymer is called vinyl polymer (D-1).

Synthesis Example 2 1,000 parts of water and 3 parts of PVA were put into a reactor equipped with a thermometer, a stirrer, a gas introduction tube and a cooling tube and dissolved. Styrene 7
20 parts, butyl acrylate 280 parts and 1,1-bis (t-
(Butylperoxy) -3,3,5-trimethylcyclohexane (4 parts) was added, and the mixture was stirred and sufficiently dispersed. Then 10 at 80 ℃
After carrying out the polymerization reaction for an hour, the temperature was further raised to 90 ° C. to complete the polymerization. By filtration and drying, a vinyl polymer having a glass transition point of 54 ° C., a number average molecular weight of 200,000 and a weight average molecular weight of 750,000 was obtained. This polymer is called vinyl polymer (D-2).

Example 1 3,022 parts of isophthalic acid, 4,800 parts of an EO2 mol adduct of bisphenol A (molar ratio of acid / glycol = 1.2) and 16 parts of dibutyltin oxide were charged into a four-necked flask at a temperature of 200 to 230 ° C. in a nitrogen stream. A dehydration condensation reaction was performed. reaction
After 16 hours, the acid value was 45.0 and the hydroxyl value was 1.5, so the reaction product was taken out. Obtained saturated polyester (B-1)
Had a glass transition point of 63 ° C. and a molecular weight of 2,400 as determined from acid value and hydroxyl value.

1,000 parts (0.42 mol) of this polyester (B-1) was dissolved in 500 parts of toluene in a 4-necked flask, and further 3 parts of glycidyl methacrylate [5 mol% based on the number of moles of (B-1)] and Add 0.2 parts of triethylenediamine and add 1
The temperature was raised to 20 ° C., and the addition reaction of glycidyl methacrylate to the polyester was performed for 3 hours. The acid value before the reaction was 30.0, but the value after the reaction was 29.4.

The obtained product is a saturated polyester (B-1) and a polyester in which glycidyl methacrylate is bonded to B-1 (A-
It is a toluene solution containing 1) (96: 4 in molar ratio).

A vinyl monomer (C-1) consisting of 444 parts of styrene and 156 parts of butyl acrylate was added to 1,200 parts of this toluene solution to make a uniform solution (this is referred to as solution [1-1]).
On the other hand, 125 parts of a 4% toluene solution of a polymerization initiator azobisisobutyronitrile (this solution is referred to as solution [1-2]) was prepared.

Similarly, 250 parts of toluene was put into a four-necked flask, and the solution [1-1] and the solution [1-2] were fed using a dropping pump while refluxing (refluxing temperature: 111 ° C) in a nitrogen stream. 2 in succession
The mixture was dropped over a period of time to carry out a polymerization reaction. The polymerization was further continued, and 10 parts of a 4% toluene solution of azobisisobutyronitrile was added every hour. Polymerization conversion of styrene is 95
%, The reaction is terminated, toluene is distilled off, and the binder (E-1) of the present invention, which is a polymer dispersion, is removed.
I got The amount of (A-1) used is 2% based on the weight of (E-1) and the amount of vinyl monomer (C-1) is 43%. (E-1) had two glass transition points at 55 ° C. and 63 ° C., and had a number average molecular weight of 6,000 and a weight average molecular weight of 70,000.

Example 2 and Comparative Example 1 Saturated polyester (B-2) was obtained by polymerizing 300 parts of terephthalic acid, 2,350 parts of phthalic anhydride and 5,170 parts of a PO2 mole adduct of bisphenol A in the same manner as in Example 1. . (B-2) had an acid value of 50.0, a hydroxyl value of 1.7, and a glass transition point of 53 ° C. The molecular weight determined from the acid value and the hydroxyl value was 2,200. (B-2) With respect to 1,000 parts (0.45 mol), 18.5 parts of glycidyl methacrylate [29 mol% based on the number of moles of (B-2)] was subjected to an addition reaction in the same manner as in Example 1, Saturated polyester (B-2) and polyester (A-
2) (77:23 in molar ratio) to obtain a toluene solution.
A solution [2-1] of a vinyl monomer (C-2) consisting of 908 parts of this toluene solution, 240 parts of styrene, and 160 parts of butyl methacrylate and a 20% toluene solution of the polymerization initiator di-tert.-butyl peroxide [2 -2] I prepared 4 parts.

250 parts of toluene, vinyl polymer (D
-1) 600 parts and 50 parts of Viscol 550P (weight-average molecular weight 15,000 of low molecular weight polypropylene manufactured by Sanyo Kasei Co., Ltd.) were charged, and a dropping pump was used while refluxing in nitrogen stream (refluxing temperature 111 ° C). Solution [2-1] and solution [2-2] were added dropwise by the same method as in Example 1 to carry out a polymerization reaction to obtain a binder (E-2) of the present invention as a polymer dispersion. The amount of (A-2) used was 8% based on the weight of (E-2), (C-
The amount of 2) is 24%, the amount of (D-1) is 36%, and the amount of low molecular weight polypropylene is 3%.

The glass transition points of (E-2) were 53 ° C. and 66 ° C., the number average molecular weight was 5,000, and the weight average molecular weight was 250,000.

A comparative binder (F-1) was obtained by carrying out a similar reaction using only the saturated polyester (B-2) without using the polyester (A-2) having a copolymerizability with a vinyl monomer.

Example 3 The saturated polyester prepared in Example 2 (B-
2) To 1,000 parts (0.45 mol), 35.5 parts of glycidyl methacrylate [56 mol% based on the number of moles of (B-2)] was subjected to an addition reaction in the same manner as in Example 1 to give polyester (B -2) and a polyester solution (A-2) reacted with glycidyl methacrylate (56:44 in molar ratio) to obtain a toluene solution. Using 908 parts of this toluene solution, a polymerization reaction was carried out in the same manner as in Example 2 to obtain a binder (E-3) of the present invention as a polymer dispersion. The amount of (A-2) used was 16% based on the weight of (E-3), the amount of (C-2) was 24%,
The amount of (D-1) is 37%, the amount of low molecular weight polypropylene is 3
%. The glass transition point of (E-3) was 53 ° C. and 66 ° C., the number average molecular weight was 5,000, and the weight average molecular weight was 250,000.

Example 4 Saturated polyester (B-3) was polymerized in the same manner as in Example 1 using 320 parts of terephthalic acid, 708 parts of an EO2 mol adduct of bisphenol A and 2 parts of dibutyltin oxide.
I got (B-3) had an acid value of 1.0, a hydroxyl value of 41.6, and a glass transition point of 55 ° C. The molecular weight determined from the acid value and the hydroxyl value was 2,600.

1,000 parts of this polyester (B-3) was melted at 150 ° C, 8 parts of maleic anhydride was added, and the reaction was carried out at 150 ° C for 1 hour. The hydroxyl value before the reaction was 41.0, but the value after the reaction was
It was 37.5. The obtained product is saturated polyester (B-
3) 83 mol% and 17 mol% of polyester (A-3) bound with maleic anhydride.

400 parts of the mixture of polyester (A-3) and polyester (B-3), 300 parts of vinyl polymer (D-2) and 50 parts of VISCOL 550P were added with 300 parts of xylene, and 235 parts of styrene and butyl were added while refluxing the system. A mixture of 65 parts of acrylate and 22 parts of t-butyl peroxybenzoate (C-3) was added to 4 parts.
The mixture was added dropwise over a period of time and refluxed for another 30 minutes to complete the polymerization reaction. The solvent was distilled off under reduced pressure to obtain a binder (E-4) of the present invention as a polymer dispersion. The amount of (A-3) used was 6% based on the weight of (E-4),
The total amount of (C-3) and (D-2) is 57%. The glass transition point of (E-4) was 55 ° C. and 60 ° C., the number average molecular weight was 6,800, and the weight average molecular weight was 290,000.

Use Examples 1 to 4 and Comparative Use Example 1 Using the binders (E-1) to (E-4) and the comparative binder (F-1), electrophotographic toners were prepared by the following method, and further electrophotographic developer was prepared. It was made.

Toner preparation method Binder 90 parts Viscole 660P 3 parts (Sanyo Kasei Kogyo Co., Ltd. low molecular weight polypropylene) Carbon black MA-100 6 parts (Mitsubishi Kasei Co., Ltd.) Aizen Spiro Black TRH 1 part (Hodogaya Chemical ( Co., Ltd.) After powder blending the above mixture, the mixture was kneaded with a Labo Plastomill at 140 ° C. × 30 rpm for 10 minutes, and the obtained kneaded product was finely pulverized with a jet mill PJM100 (manufactured by Nippon Pneumatic Co., Ltd.). An air flow classifier MDS (manufactured by Nippon Pneumatic Co., Ltd.) was used to cut fine powder of 5 μm or less from the finely pulverized product. Aerosil R972 (manufactured by Nippon Aerosil Co., Ltd.) 3 in 1,000 parts of the obtained powder.
The parts were uniformly mixed to obtain a toner.

Developer Preparation Method An electrophotographic developer was obtained by mixing 25 parts of the above toner with 1,000 parts of an electrophotographic carrier iron powder (F-100 manufactured by Nippon Iron Powder Co., Ltd.).

 The evaluation results are shown in Table-1, Table-2 and Table-3.

All of the binders (E-1) to (E-4) of the present invention have an excellent dispersed state in the toner as compared with the comparative binder (F-1), and also have an excellent pulverizability in forming a toner. In addition, the toner has a wide temperature range between MF and HO, has good fixing performance as a toner, and has excellent image stability.

[Advantages of the Invention] The binder of the present invention is a binder in which a styrene resin and a polyester are uniformly dispersed in a particle size equal to or smaller than the toner particle size, which cannot be achieved by conventional techniques. Since the dispersion is fine and uniform, the toner is evenly charged, and good image quality that can be used for a long period of time can be obtained. Further, since the respective properties of styrene resin and polyester are effectively exhibited, it becomes possible to design and manufacture a well-balanced binder.

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Claims (4)

(57) [Claims] 1. A toner binder comprising a polyester and a vinyl polymer, wherein the binder copolymerizes vinyl monomer (C) and polyester (A) copolymerizable with (C) in polyester (B). Binder for toner, which is a uniform dispersion of 2. A toner binder comprising polyester and a vinyl polymer, wherein the binder is a polyester (A) copolymerizable with the vinyl monomer (C) and (C) in the polyester (B) and the vinyl polymer (D). ) Is a uniform dispersion obtained by copolymerizing with a binder for a toner. 3. The binder for a toner according to claim 1, wherein the copolymerizable polyester (A) is used in an amount of 1 to 20% of all the constituent components. 4. The vinyl polymer or polyester is 2 μm.
The binder for toner according to claim 1, which is uniformly dispersed below.