JP3038554B2 - Toner binder for electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a toner binder for electrophotography.

[0002]

2. Description of the Related Art In an electrophotographic process using a powdery dry toner, a contact heating type fixing device (a method using a heat roll, a method using a heat roll and a paper) is used to fix toner transferred onto paper or the like. Through a film or a belt (for example, JP-A-4-70688 and JP-A-4-70688).
No. 12558) has been widely adopted. In this method, it is desirable that the minimum fixing temperature (hereinafter abbreviated as MFT) is low (low-temperature fixability), and the temperature at which hot offset occurs on the heat roll surface, film or belt (hereinafter abbreviated as HOT) is high. Is desirable (hot offset resistance). In order to obtain a clear image, a toner having a high triboelectric charge is preferable (charging characteristics).

Conventionally, polystyrene resins, styrene-acrylic copolymers, polyester resins, epoxy resins, and the like have been generally used as binder components of the dry toner. Among them, polystyrene resins are preferred in terms of performance such as grindability and chargeability and cost. Based resins and styrene-acrylic resins are widely used. In order to satisfy low-temperature fixability and hot offset resistance, many methods have been proposed for improving the resin by widening the molecular weight distribution of the resin. As a method of broadening the molecular weight distribution, a method of using a vinyl-based crosslinking agent for a vinyl-based resin (Japanese Patent Laid-Open No. 61-215558)
JP-A-63-44665, JP-A-63-44665
No. 223014, Japanese Unexamined Patent Publication No. 4-202307)
In the molecular weight distribution, the high molecular weight and low molecular weight
Binder having two peaks (JP-B-63-3218)
No. 0, JP-B-63-32382) or a binder obtained by crosslinking a carboxyl group-containing vinyl resin with a glycidyl compound (JP-A-6-11890, JP-A-6-222612).

[0004]

However, as described above, in the case of a binder containing only a crosslinked structure or a binder consisting of only a high molecular weight compound and a low molecular weight compound, the kneaded portion in the toner-forming step causes the formation of a crosslinked portion or a high molecular weight compound. Since the molecular portion is severely cut and the melt elasticity of the toner tends to be low, a lot of crosslinking components and high molecular weight components will be used to maintain hot offset resistance, and the melt viscosity of the resin will increase, The low-temperature fixability of the toner becomes insufficient. In addition, in the conventional method of crosslinking by utilizing the reaction of the functional group in the polymer, if the amount of the functional group is increased to increase the HOT and the degree of crosslinking of the binder is increased, the amount of the polar group is increased, and the charge of the binder is increased. Insufficient properties. As described above, in the conventional technology, in recent years, demands for high image quality of copiers, facsimiles, and printers, and trends for more hot offset resistance and lower-temperature fixing properties due to faster and smaller hardware are increasing. It is hard to say that we can handle it enough.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is a toner binder having excellent charging characteristics when formed into a toner. As a result of intensive studies aimed at obtaining a toner binder having excellent fixability, the present invention has been achieved. That is, the present invention provides an electrophotographic toner binder comprising a styrene-acrylic resin (A) having a carboxyl group and a styrene resin or a styrene-acrylic resin (B) having a functional group (b) that reacts with the carboxyl group. In (A), the weight average molecular weight is 2
It consists of a high molecular weight compound (C) having a molecular weight of 100,000 to 2,000,000 and a low molecular weight compound (D) having a weight average molecular weight of 3,000 to 50,000. The acid value of (C) is smaller than 10, and the acid value of (D) is (C) An electrophotographic toner binder having an acid value of 1/3 or less.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As a method for obtaining the styrene-acrylic resin (A) having a carboxyl group of the present invention, a method of copolymerizing a vinyl monomer having a carboxyl group with a styrene monomer and an acrylic monomer is preferable. Examples of the vinyl monomer having a carboxyl group include monoesters of unsaturated dibasic acids such as (meth) acrylic acid, maleic acid, fumaric acid, cinnamic acid, and monobutyl maleate. Among these, (meth) acrylic acid and monobutyl maleate are preferred.

The styrene monomer used for the styrene-acrylic resin (A) having a carboxyl group includes:
Styrene, α-methylstyrene, p-methoxystyrene, p-hydroxystyrene, p-acetoxystyrene and the like can be mentioned. Examples of the acrylic monomer include alkyl groups having 1 to 1 carbon atoms, such as butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate.
8 alkyl (meth) acrylate.
To increase the elasticity of the binder, a divinyl compound such as divinylbenzene, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, or divinyltoluene is used in an amount of 0.00001. ~ 0.01
It is preferable to use mol%. More preferably, it is 0.
0.0005 to 0.001 mol%. Further, other vinyl monomers other than these styrene monomers and acrylic monomers may be copolymerized. Examples of other vinyl monomers include vinyl esters such as vinyl acetate; vinyl ethers such as vinyl ethyl ether; aliphatic hydrocarbon vinyl such as α-olefin, isoprene, butadiene; and (meth) acrylonitrile.

The styrene-acrylic resin (A) comprises a high molecular weight compound (C) and a low molecular weight compound (D), and the weight average molecular weight of (C) is from 200,000 to 2,000,000, preferably from 30 to 200,000.
It is 10,000 to 1,800,000, more preferably 400,000 to 1,500,000. If the weight average molecular weight is smaller than 200,000, the HOT of the toner decreases. When the weight average molecular weight exceeds 2,000,000, the MFT of the toner becomes high. The glass transition point of (C) is usually 40 ° C to 80 ° C. The acid value of (C) is smaller than 10, preferably 9.5 to 0.05, and more preferably 9 to 0.1. If the acid value of (C) is larger than 10, the charging characteristics will deteriorate.

As the polymerization method for producing (C), any method such as solution polymerization, bulk polymerization, and suspension polymerization can be selected. The polymerization initiator is not particularly limited. For example, azo initiators such as azobisisobutyronitrile and azobisisovaleronitrile; benzoyl peroxide, di-t-butyl peroxide, lauroyl peroxide, dicumyl Peroxide initiators such as peroxides; 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) 3,3,5- Polyfunctional polymerization initiators having two or more peroxide groups in one molecule such as trimethylcyclohexane and di-t-butylperoxyhexahydroterephthalate; 1 such as diallylperoxydicarbonate and t-butylperoxyallylcarbonate; Multifunctional having one or more peroxide groups and one or more polymerizable unsaturated groups in the molecule Such as polymerization initiators, and the like. Of these, preferred are polyfunctional polymerization initiators.

The solvent used when (C) is obtained by solution polymerization is not particularly limited, but toluene, xylene,
Aromatic solvents such as ethylbenzene, ester solvents such as ethyl acetate and butyl acetate, dimethylformamide,
Dimethyl sulfoxide, methyl ethyl ketone and the like can be mentioned. Preferred are dimethylformamide, xylene and toluene.

When (C) is obtained by suspension polymerization,
Polymerization can be carried out in water using an inorganic salt dispersant such as calcium carbonate and calcium phosphate, and an organic dispersant such as polyvinyl alcohol and methylated cellulose. The polymerization temperature is usually 50 to 160 ° C, preferably 60 to 140.
° C. The polymerization is preferably performed in the presence of an inert gas such as nitrogen.

The low molecular weight compound (D) has a weight average molecular weight of 30.
00 to 50000, preferably 3500 to 400
00, more preferably 4,000 to 30,000. If the weight average molecular weight is smaller than 3000, the heat-resistant storage stability of the toner decreases. If the weight average molecular weight exceeds 50,000, the MFT of the toner becomes high. The glass transition point of (D) is usually 40 ° C to 80 ° C. The acid value of (D) is 1/3 or less of the acid value of (C). Preferably 1 /
5 or less, more preferably 1/10 or less. If it exceeds, the charging characteristics of the toner become poor. Also H
OT also decreases.

As the polymerization method for producing (D), any method such as solution polymerization, bulk polymerization and suspension polymerization can be selected. Of these, solution polymerization is preferred.
When (D) is polymerized by solution polymerization, it can be polymerized by the solution polymerization method described above. The polymerization initiator for polymerizing (D) is not particularly limited, and includes the polymerization initiators described above. Preferred among these are monofunctional initiators.

The weight ratio of the high molecular weight compound (C) to the low molecular weight compound (D) in (A) is usually from 70/30 to 5/95.
Preferably it is 60/40 to 10/90. More preferably, it is 50/50 to 20/80. The glass transition point (Tg) of (A) is usually from 40 to 80 ° C, and preferably from 50 to 70 ° C, from the viewpoint of heat-resistant storage stability when formed into a toner and MFT when formed into a toner. The acid value of (A) is
It is usually 0.01 to 7 from the viewpoint of charging characteristics. Preferably it is 0.05-5, More preferably, it is 0.1-4.

The functional group (b) which reacts with a carboxyl group includes a glycidyl group, oxazoline group, isocyanate group, amino group and the like. Among these, a glycidyl group is preferred. A reactive functional group (b) is added to the styrene resin or the styrene-acrylic resin (B) of the present invention.
Is introduced by copolymerizing a vinyl monomer having a reactive functional group (b) with a styrene monomer or a styrene monomer and an acrylic monomer in the same manner as in the case of introducing a carboxyl group into (A) described above. Obtainable. Examples of the vinyl monomer having a glycidyl group include glycidyl (meth) acrylate, β-methyl glycidyl (meth) acrylate, and allyl glycidyl ether. Among these, glycidyl (meth) acrylate is preferred. Examples of the vinyl monomer having an isocyanate group include m-isopropenyl-α, α-dimethylbenzyl isocyanate, methacryloyl isocyanate, and 2-isocyanatoethyl methacrylate. Of these, m-isopropenyl-α, α-dimethylbenzyl isocyanate is preferred. Examples of the vinyl monomer having an oxazoline group include 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, and 2-vinyl-4-
Methyl-2-oxazoline and the like. Preferred among these is 2-isopropenyl-2-oxazoline. Examples of the vinyl monomer having an amino group include aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, 4-vinylpyridine,
-Vinyl pyridine and the like. Among these, a tertiary amino group-containing (meth) acrylate is preferred. The monomer to be copolymerized with the monomer having (b) is a styrene monomer, an acrylic monomer,
Other vinyl monomers and the like can be mentioned. Preferred among these are styrene, butyl (meth) acrylate,
It is an alkyl (meth) acrylate having an alkyl group of 1 to 18 carbon atoms, such as 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate.

As the polymerization method for producing (B), any method such as solution polymerization, bulk polymerization and suspension polymerization can be selected. Of these, solution polymerization is preferred.
When (B) is polymerized by solution polymerization, it can be polymerized by the solution polymerization method described above. The polymerization initiator for polymerizing (B) is not particularly limited, and examples thereof include the polymerization initiators described above.

The weight average molecular weight (BMW) of (B) used in the present invention is usually from 3000 to 100,000, preferably from 3500 to 70,000, and more preferably from 4000 to 50,000. The glass transition point of (B) is usually 30 ° C to 150 ° C.
° C, preferably 35 ° C to 90 ° C, more preferably 40 ° C to 80 ° C. The content of (b) in (B) is based on the number of grams (b) of the resin containing 1 gram equivalent of (b).
g) is from 1000 g / eq to 20,000 g / eq, preferably from 1500 g / eq to 15000 g / eq, more preferably from 2000 g / eq to 10,000 g / eq.

The method for producing the resin for toner according to the present invention comprises the steps of (A)
And (B) are blended and obtained by heating. Although (A) and (B) can be heated in the reaction vessel, it is preferable to react (A) and (B) in a heated and molten state using a kneader or the like in order to increase the viscosity. Further, when (A) and (B) are blended as a powder to prepare a toner, the toner can be heated and reacted. The weight ratio of (A) and (B) is usually 0.1 part to 30 parts for (B) with respect to 100 parts of (A). Preferably (B) is 0.2 to 15 parts, more preferably 0.5 to 10 parts. The equivalent of the functional group of (b) per equivalent of the carboxyl group of (A) is usually 1.6 to 20.000 when the acid value of (A) is smaller than 1.
0. It is preferably 1.8 to 10.0, and more preferably 2.0 to 5.0. When the acid value of (A) is 1 or more, it is usually 0.001-1, preferably 0.005-0.5.
1, more preferably 0.01 to 0.05.

An example of a method for producing an electrophotographic toner which is used for the toner binder of the present invention is as follows. The toner binder is usually 45 to 95% by weight based on the weight of the toner, and a known coloring agent (carbon black, iron black, Benzidine yellow, quinacdrine, rhodamine B, phthalocyanine, etc.)
Is usually used in a proportion of 5 to 10% by weight and magnetic powder (compounds of iron, cobalt, nickel, hematite, ferrite, etc.) is usually used in a proportion of 0 to 50% by weight, and various additives [charge adjusting agent (metal complex, nigrosine, nigrosine) are used. ), Lubricants (such as polytetrafluoroethylene, low molecular weight polyolefins, fatty acids, or metal salts or amides thereof) and the like]. The amount of these additives is usually 0 to 10% by weight based on the weight of the toner. The electrophotographic toner is dry-blended with the above components, melt-kneaded, coarsely pulverized, and finally finely pulverized using a jet pulverizer or the like to obtain fine particles having a particle size of 5 to 20 μm. The electrophotographic toner, if necessary, iron powder, glass beads,
It is used as a developer for an electric latent image by being mixed with carrier particles such as nickel powder and ferrite. Further, hydrophobic colloidal silica fine powder can be used to improve the fluidity of the powder. The electrophotographic toner includes a support (paper,
It is fixed on a polyester film and used. The fixing method is as described above.

[0020]

The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples. Hereinafter, "part" indicates "part by weight". The methods for measuring the properties of the resins obtained in Synthesis Examples, Examples and Comparative Examples are described below.

Molecular weight measurement apparatus: HLC-802A manufactured by Tosoh Corporation Conditions: column TSK gel GMHXL 2 columns manufactured by Tosoh Corporation Measurement temperature: 40 ° C. Sample solution: 0.25 wt% tetrahydrofuran solution Solution injection amount: 100 μl Detector: Refraction Rate detector The molecular weight calibration curve was created using standard polystyrene.

Glass transition point (Tg) measurement device: DSC20, SS manufactured by Seiko Denshi Kogyo KK
C / 580 Condition: ASTM (D3418-2) method

Preparation of Resin (C) Production Example 1 764.8 parts of styrene, 234 parts of n-butyl acrylate, 1.2 parts of monobutyl maleate were placed in an autoclave reactor equipped with a thermometer, a stirrer and a nitrogen inlet tube. , 0.15 parts of divinylbenzene as a mixed monomer, and as an initiator,
0.5 part of 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane is added, and in a nitrogen stream,
After polymerization at 90 ° C. for 5 hours, 245 parts of xylene was added, polymerization was performed at 90 ° C. for 1 hour, and then polymerization was performed at 110 ° C. for 1 hour. Further, 0.1 part of 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane and xylene 1
After adding 22 parts and polymerizing at 110 ° C for 4 hours,
Then, 1 part of di-t-butyl peroxide and 25 parts of xylene were charged and polymerized for 2 hours to complete the polymerization, and the solvent was removed under reduced pressure to obtain a resin (C1). GP of (C1)
The weight average molecular weight by C is 700,000, and the glass transition point is 60.
° C, the acid value was 0.40.

Production Example 2 760.5 parts of styrene mixed with n-acrylic acid
Resin (C2) was obtained in the same manner as in Production Example 1, except that 234 parts of butyl, 5.5 parts of monobutyl maleate, and 0.15 part of divinylbenzene were used. The weight average molecular weight by GPC of (C2) was 700,000, the glass transition point was 61 ° C., and the acid value was 1.8.

Production Example 3 754.4 parts of styrene mixed with n-acrylic acid
Resin (C3) was obtained in the same manner as in Production Example 1, except that 234 parts of butyl, 11.6 parts of acrylic acid, and 0.15 part of divinylbenzene were used. The weight average molecular weight by GPC of (C3) was 680,000, the glass transition point was 59 ° C, and the acid value was 9.0.

Production Example 4 750.6 parts of styrene, n-acrylic acid
A resin (C4) was obtained in the same manner as in Production Example 1 except that 234 parts of -butyl, 15.4 parts of acrylic acid, and 0.15 part of divinylbenzene were used. The weight average molecular weight by GPC of (C4) was 650,000, the glass transition point was 60 ° C, and the acid value was 12.12.
It was 0.

Preparation Example 5 200 parts of xylene was placed in the same apparatus as in Preparation Example 1, and after purging with nitrogen, 782.7 parts of styrene and 140 g of acrylic acid were added at 140 ° C.
Butyl part, 2.3 parts of acrylic acid, and di-t-butyl peroxide 1.5 as an initiator.
Of xylene and 100 parts of xylene were added dropwise over 3 hours. After dropping, the mixture was aged at 145 ° C. for 3 hours to complete the polymerization. Thereafter, the solvent was removed under reduced pressure to obtain a resin (C5). The weight average molecular weight by GPC of (C5) is 100,000,
The glass transition point was 61 ° C. and the acid value was 1.8.

Preparation of Resin (D) Production Example 6 452 parts of xylene was placed in the same apparatus as in Production Example 1, and after replacing with nitrogen, a mixed monomer of 845 parts of styrene and 155 parts of n-butyl acrylate was added at 170 ° C. and an initiator. As di-t-
A mixture of 6.4 parts of butyl peroxide and 125 parts of xylene was added dropwise over 3 hours. After dropping, the mixture was aged at 170 ° C. for 1 hour to complete the polymerization. Thereafter, the solvent was removed under reduced pressure to obtain a resin (D1). The weight average molecular weight by GPC of (D1) was 13,000, and the glass transition point was 59 ° C.
Met.

Production Example 7 844.3 parts of styrene, n-acrylic acid
Resin (D2) was obtained in the same manner as in Production Example 6 except that 155 parts of butyl and 0.7 parts of acrylic acid were used. GP of (D2)
The weight average molecular weight by C is 13,000 and the glass transition point is 5
At 9 ° C., the acid value was 0.50.

Production Example 8 839.9 parts of styrene mixed with n-acrylic acid
Resin (D3) was obtained in the same manner as in Production Example 6 except that 155 parts of butyl and 5.1 parts of acrylic acid were used. GP of (D3)
The weight average molecular weight by C is 13,000 and the glass transition point is 5
At 9 ° C., the acid value was 4.0.

Production Example 9 Resin (D) was prepared in the same manner as in Production Example 5 except that the mixed monomer was 800 parts of styrene, 200 parts of n-butyl acrylate, and the initiator was 4.94 parts of di-t-butyl peroxide.
4) was obtained. The weight average molecular weight by GPC of (D4) was 60,000, and the glass transition point was 60 ° C.

Preparation of Resin B Production Example 10 Production was conducted except that the mixed monomer was 802 parts of styrene, 135 parts of n-butyl acrylate, 63 parts of glycidyl methacrylate, and 15.4 parts of di-t-butyl peroxide as an initiator. In the same manner as in Example 6, a resin (B1) was obtained. (B
The weight average molecular weight by GPC of 1) is 9000, the glass transition point is 53 ° C., and the glycidyl group equivalent is 2254 g / eq.
Met.

Production Example 11 Resin (B2) was obtained in the same manner as in Production Example 6, except that the mixed monomer was 798 parts of styrene, 171 parts of n-butyl acrylate, and 31 parts of glycidyl methacrylate. (B
2) The weight average molecular weight by GPC is 12,000, the glass transition point is 53 ° C., and the glycidyl group equivalent is 4581 g / eq.
Met.

Production Example 12 805 parts of styrene, 145 parts of n-butyl acrylate and 2-isopropenyl-2-oxazoline 5
A resin (B3) was obtained in the same manner as in Production Example 6 except that the amount was 0 part. The weight average molecular weight by GPC of (B3) was 1.2.
Glass transition point is 55 ° C, oxazoline group equivalent is 22
It was 20 g / eq.

Production Example 13 Resin (B4) was prepared in the same manner as in Production Example 6 except that 768 parts of styrene, 145 parts of n-butyl acrylate, and 87 parts of m-isopropenyl-α, α-dimethylbenzyl isocyanate were used. I got The weight average molecular weight by GPC of (B4) was 12,000, the glass transition point was 55 ° C., and the isocyanate group equivalent was 2310 g / eq.

Preparation of Resin (A) Production Examples 14 to 20 100 parts of xylene was charged into a cooling pipe and a kolben equipped with a stirrer, and the amount of (D) shown in Table 1 was added and dissolved.
(C), and after nitrogen replacement, stirring at 150 ° C. for 2 hours.
Stir for an hour to dissolve uniformly. Thereafter, the solvent was removed under reduced pressure at 170 ° C. to obtain resins (A1) to (A7). Table 1 shows (A)
The Tg and the analysis value of the acid value are shown together.

[0037]

[Table 1] ------------------- Resin (C) (D) Tg ° C Acid value ------ −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− 14 A1 C1 40 parts D1 60 parts 59 0.15 15 A2 C2 40 parts D1 60 parts 60 0.70 16 A3 C2 40 Part D2 60 part 60 0.98 Structure 17 A4 C3 40 part D1 60 part 59 3.50 18 A5 C3 40 part D3 60 part 59 5.80 Example 19 A6 C2 40 part D4 60 part 60 0.69 20 A7 C5 40 part D1 60 part 60 5.00 −− −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

Examples 1 to 10 Resins (A) obtained in Production Examples 14 to 17 and
The resin (B) obtained in 13 was powder-blended at the compounding ratio shown in Table 2 and melt-kneaded by a twin-screw extruder at an internal temperature of 210 ° C.
(A) and (B) were reacted to obtain the toner binders (TB1) to (TB7) of the present invention.

[0039]

[Table 2] -------------------- Resin (A) (B) --------- −−−−−−−−−−−−−−−−−−−−−− 1 TB1 A1 100 B1 6.3 Part 2 TB2 A2 100 B1 6.3 3 TB3 A2 100 B2 12.6 Part 4 TB4 A2 100 parts B3 6.3 parts 5 TB5 A2 100 parts B4 6.3 parts Example 6 TB6 A3 100 parts B1 12.6 parts 7 TB7 A4 100 parts B2 1.0 parts---------------------- −−−−−−−−−−−−

Comparative Examples 1 to 6 Comparative toner binders (TB8 to TB10) were obtained by using the components shown in Table 3 in the same manner as in Example 1.

[0041]

[Table 3] ------------------------------------------ Resin (A) (B) -------------- −−−−−−−−−−−−−−−−−−−−− Ratio 1 TB8 A5 100 parts B2 1.5 parts Comparison 2 TB9 A6 100 parts B1 6.3 parts Example 3 TB10 A7 100 parts B1 1.0 part −− −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

Use Examples and Comparative Use Examples The evaluation of the toner binder was performed in two ways: a two-component development system and a one-component development system. Evaluation of Two-Component Development Method In each of 88 parts of the toner binder of the present invention of Examples 1 to 7 and the toner binder of Comparative Examples 1 to 3, 7 parts of carbon black (MA100 manufactured by Mitsubishi Kasei Co., Ltd.) and low molecular weight polypropylene (Sanyo) Viscole 5 manufactured by Kasei Kogyo Co., Ltd.
After uniformly mixing 3 parts of 50P) and 2 parts of a charge controlling agent (Spiron Black TRH manufactured by Hodogaya Chemical Industry Co., Ltd.), the mixture was kneaded with a twin-screw extruder at an internal temperature of 150 ° C., and the cooled product was finely pulverized with a jet mill. The resulting mixture was classified by a dispersion separator to obtain toners a to j having an average particle diameter of 12 μm.

Test Example 1 To 3 parts of each of the toners a to j, 97 parts of a ferrite carrier (F-100 manufactured by Powdertech Co., Ltd.) were mixed uniformly,
A toner image is transferred onto paper using a commercially available copying machine (BD-7720, manufactured by Toshiba Corporation), and the transferred toner is remodeled into a fixing unit of a commercially available copying machine (SF8400A, manufactured by Sharp Corporation). The fixing test was performed at a speed of 35 sheets of A4 paper per minute. The image quality was determined based on the image density after fixing. The test results are as shown in Table 4.

Test Example 2 Each of the toners a to j was placed in a polyethylene bottle,
After being kept in a constant temperature water bath at 45 ° C. for 8 hours, the mixture was transferred to a 42-mesh sieve and shaken for 10 seconds using a powder tester manufactured by Hosokawa Micron Corp., and the weight% of the toner remaining on the sieve was measured. Sex test.
The smaller the number, the better the heat-resistant storage stability. If it is less than 35%, it can be used without any problem. Table 4 shows the results.

[0045]

Table 4 −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− Toner Toner MFT HOT Image resistance Heat resistance Heater interface (° C) (° C) Storage property * 1 * 2 * 3 (%) ---------------------------------- b TB2 130> 240 ◎ 26 Application c TB3 130> 240 ◎ 25 d TB4 133 240 ○ 26 Example e TB5 133 235 ○ 27 f TB6 132 235 ◎ 26 g TB7 131 240 ○ 28 −−−−−−−−−−− −−−−−−−−−−−−−−−−−−−−−− Ratio h TB8 133 200 ○ 28 Comparison i TB9 145> 240 ◎ 26 Example j TB10 140 200 △ 26 −−−−−−− ------------------------------------------------------------------* * Rubs with 5 reciprocations to obtain a copy in which the image density of the solid portion after rubbing was 70% or more. Heat roll temperature of time. * 2 Heat roll temperature when toner is hot offset * 3 ３: Image density (I.D)> 1.4, ：: (I.D) 1.0 to 1.4, Δ: (I.D) <1.0

In the evaluation by the two-component developing method, all of the toners a to g using the binder of the present invention have higher heat storage stability than the toners h to j using the comparative binder.
Excellent balance between low-temperature fixability and hot offset resistance without impairing image quality. In particular, toners a to g comprising a toner binder in which the acid value of the high molecular weight compound (C) is smaller than 10 and the acid value of (D) is 1/3 or less of the acid value of (C) are excellent in all performances. .

Evaluation of one-component developing system 48.8 parts of each of the toner binder of the present invention of Examples 1 to 7 and the toner binder of Comparative Examples 1 to 3 were added with magnetic powder (EPT-1000 manufactured by Toda Kogyo KK) 48 .8 copies,
After uniformly mixing 2 parts of low molecular weight polypropylene (Himer TP-32 manufactured by Sanyo Chemical Industry Co., Ltd.) and 0.4 part of charge control agent (T-77 manufactured by Hodogaya Chemical Industry Co., Ltd.),
The mixture was kneaded with a twin-screw extruder at an internal temperature of 130 ° C., and the cooled product was finely pulverized with a jet mill and classified with a dispersion separator to obtain toners A to J having an average particle size of 8 μm.

Test Example 3 Toners A to J were used to transfer a toner image onto paper using a commercially available laser beam printer (manufactured by Canon Inc., LBP-210), and the transferred toner on paper was compared to Test Example 1 described above. A fixing test and evaluation of image quality were performed in the same manner. The test results are as shown in Table 5.

Test Example 4 Toners A to J were tested for heat resistance in the same manner as in Test Example 2. If it is less than 35%, it can be used without any problem. Table 5 shows the results.

[0050]

Table 5 ----------------------------------------------------------------------------------------- Toner Toner MFT HOT Image resistance Heat resistance Heater interface (℃) (℃) Storage Properties * 1 * 2 * 3 (%) ---------------------------------- 133> 240 ◎ 26 Application C TB3 133> 240 ◎ 25 D TB4 135 235 ○ 26 Example E TB5 136 235 ○ 27 F TB6 134 235 ◎ 26 G TB7 134 240 ○ 28 −−−−−−−−−−−−− −−−−−−−−−−−−−−−−−−− Ratio H TB8 135 195 ○ 28 Comparison I TB9 148> 240 ◎ 26 Example J TB10 143 190 △ 26 −−−−−−−−−− ----------------------------------------------------------- ), The copy was rubbed two times and the image density of the solid portion after rubbing remained 70% or more. Heat roll temperature at the time was. * 2 Heat roll temperature when toner is hot offset * 3 ３: Image density (I.D)> 1.4, ：: (I.D) 1.0 to 1.4, Δ: (I.D) <1.0

In the evaluation by the one-component developing system, the toners A to G using the binder of the present invention all have higher heat storage stability than the toners H to J using the comparative binder.
Particularly, the acid value of the high molecular weight compound (C) is less than 10, and the acid value of (D) is one of the acid value of (C), which is excellent in balance between low-temperature fixability and hot offset resistance without impairing image properties.
Toners A to G having a toner binder of / 3 or less are excellent in all performances.

[0052]

As described above, the toner binder of the present invention maintains a heat-resistant storage property and a low-temperature fixing property by introducing a small amount of a reactive functional group to obtain a toner excellent in image properties and hot offset resistance. Can be

Claims (4)

(57) [Claims] 1. An electrophotographic toner binder comprising a styrene-acrylic resin having a carboxyl group (A) and a styrene resin or a styrene-acrylic resin having a functional group (b) that reacts with a carboxyl group. In (A), a high molecular weight substance (C) having a weight average molecular weight of 200,000 to 2,000,000 and a weight average molecular weight of 3,000 to 200,000
An electrophotographic toner binder comprising a low molecular weight compound (D) having a molecular weight of 50,000, an acid value of (C) being less than 10, and an acid value of (D) being 1/3 or less of an acid value of (C). 2. The binder according to claim 1, wherein (C) contains 0.00001 to 0.01 mol% of a divinyl monomer as a constitutional unit. 3. The binder according to claim 1, wherein the carboxyl group in (A) and at least a part of (b) in (B) react. 4. The method according to claim 1, wherein (b) is a glycidyl group.
4. The binder according to any one of the above items 3.