JP3128907B2 - Color toner for electrostatic image development - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color toner for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing and the like.

[0002]

2. Description of the Related Art In electrophotography, a photoconductive substance is generally used to form an electrostatic image on a photoreceptor by various means, and the electrostatic image is developed with a toner. Is established.

[0003] The rapid development of the information society in recent years is due to the fact that in the field of electrophotography such as copying machines and printers, recording copies have been made.
There is a demand for higher speed, higher color, and sharper image quality, and as a binder resin used for toner, a resin having more excellent fixing performance and good color coloring is desired.

[0004] As such a binder resin, for example, a styrene-acryl resin as disclosed in Japanese Patent Publication No. 55-6895 and an epoxy resin as disclosed in Japanese Patent Application Laid-Open No. 62-67562 are used. As seen in JP-A-60-112052, it is suitable for high-speed copying because of its excellent fixability.

[0005] However, polyester resins are toner-based.
When the binder resin is used as a binder resin, the toner tends to accumulate due to friction between the toner and the carrier or the developing magnet roll during continuous copying to easily cause thermal agglomeration.
In the heat fixing method, a toner image transferred to paper or the like directly contacts the surface of the heat roller, and the toner is melted and fixed on the paper or the like by the heat and pressure of the heat roller. However, at this time, a part of the toner image adheres to and transfers to the roller surface, and the transferred material re-transfers to the next transfer material such as paper. In particular, polyester resins tend to have such a tendency, and improvement thereof is desired.

In order to improve these problems, Japanese Patent Publication No. Sho 62
JP-A-39428 discloses a toner using a blend of an amorphous polyester and a crystalline polyester. Block copolymerized polyesters having partially crystalline segments are also disclosed in, for example, JP-A-50-8
No. 7032.

The techniques described in these publications all attempt to lower the minimum fixing temperature of the toner by introducing a crystalline polyester and improve the offset resistance, and the effect in that respect is recognized. However, since each of them contains a crystalline segment or crystalline polymer chain having a low Tg, the Tg as a toner is not sufficiently high, the pulverizability at room temperature is poor, and thermal aggregation is liable to occur. .

[0008] Moreover, since resins containing these crystalline polyesters are generally not colorless and transparent, even if they are used for color toners, they become turbid hues and are not suitable as binder resins for color toners.

[0009]

DISCLOSURE OF THE INVENTION The present invention relates to an electrostatic image developing method which uses a polyester resin having a specific composition as a binder resin to improve the fixing property, heat cohesion resistance, offset resistance and color developing properties. It is intended to provide a color toner.

[0010]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention.

That is, according to the present invention, the polybasic acid component comprises terephthalic acid as a main component, and the polyhydric alcohol component comprises 1,4-cyclohexanedimethanol (A) and glycol (B) represented by the following formula (1). A molar ratio of (A) :( B) is 35:65 to 65:35, and the total of (A) and (B) is 90 mol% in the polyhydric alcohol component.
The glass transition temperature Tg is 55 to 75 ° C., the weight average molecular weight Mw is 5,000 to 20,000, the melt viscosity at 100 ° C. is 10 ⁴ to 10 ⁶ poise, and the ring method softening point SP is contained.
Is a color toner for developing an electrostatic image, comprising a polyester resin as a binder resin.

[0012]

Embedded image

(Wherein, R is an alkylene group having 2 or 3 carbon atoms, m and n are integers, and 2 ≦ m + n ≦
4. The present inventors have studied various polyester resins containing 1,4-cyclohexane dimethanol as an essential component of glycol, as described in Japanese Patent Application No. 2-115172, The inventors have found that a polyester resin having a glass transition temperature Tg, a weight average molecular weight Mw, a melt viscosity, and a softening point SP of a ring and ball method is extremely excellent particularly as a binder resin for a color toner, and have reached the present invention.

The polyester resin used as the binder resin in the present invention has intermediate properties between crystalline and amorphous due to its specific component composition ratio and glass transition temperature, etc. It has good properties and also has complete colorless transparency which is indispensable for color toners.

As the polyvalent alcohol component constituting the polyester resin in the present invention, 1,4-cyclohexanedimethanol (A) and glycol (B) represented by the formula (1) are essential components. . Among the glycols (B) represented by the formula (1), a 2-mol adduct of bisphenol A with ethylene oxide or a 2-mol adduct of propylene oxide is preferable, and a 2-mol adduct of ethylene oxide is particularly preferable.

In addition to 1,4-cyclohexanedimethanol (A) and glycol (B) represented by the formula (1), other polyvalent alcohols which can be used in combination therewith include ethylene glycol and triglycol. Ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,
1,4-butanediol, 1,3-butanediol,
1,4-butenediole, 1,5-pentanedio-
, 1,6-hexanediol, hydrogenated bisphenol A
And divalent alcohols such as glycerin, trimethylolethane, trimethylolpropane, trishydroxyethyl isocyanurate and pentaerythritol. Can be used together with a small amount of less than 10 mol% within a range that does not impair.

The molar ratio (A) of the polyhydric alcohol component constituting the polyester resin in the present invention, 1,4-cyclohexanedimethanol (A), to the glycol (B) represented by the formula (1): (B) is preferably in the range of 35:65 to 65:35, and particularly preferably in the range of 40:60 to 60:40.

When the use ratio of 1,4-cyclohexanedimethanol exceeds 65 mol%, the tendency of crystallization is too large, the resin itself becomes completely opaque, the transparency which is the object of the present invention is good, and the coloring property is high. Good color toner cannot be obtained.

Conversely, if the proportion of 1,4-cyclohexanedimethanol used is less than 35 mol%, not only the polyester resin of the present invention does not exhibit the semi-crystalline property but also the polyester resin itself becomes yellow-brown. The tendency of coloring is increasing, and it is not possible to provide a toner for a digital color copying machine which requires precise color management. Further, in the present invention, as a polyhydric alcohol component, the total of 1,4-cyclohexanedimethanol and the glycol represented by the formula (1) is 90 mol% or more in the polyhydric alcohol component, and the glass transition temperature is lowered. It is necessary because it is maintained at 55 to 75 ° C.

The polybasic acid component contains terephthalic acid as a main component, the molar ratio of the polyhydric alcohol component (A) :( B) is in the range of 35:65 to 65:35, and the glass transition temperature Tg is 55 to 55. 75 ° C., weight average molecular weight Mw is 5000
20,000, melt viscosity at 100 ° C. is 10 ⁴ -1
0 ⁶ poise, the ring and ball softening point SP is at 90 to 120 ° C., surprisingly, the polyester resin exhibits a state should be called a semi-crystalline.

The degree of transparency of the resin is determined by the haze value (haze value).
Is displayed with. The polyester resin for a color toner in the present invention preferably has a haze value of 20 or less. Polyester resin used in the color toner of the present invention,
When the resin is heated and melted to 220 ° C. or more and rapidly cooled to room temperature (cooling rate of 100 ° C./min or more), the haze value becomes 20 or less and the resin becomes transparent, but gradually cooled (cooling rate of 0.1 ° C./min or less) ), An haze value of 70 or more gives an opaque (crystallized) state.

If the cooling is industrially feasible and still is opaque, it cannot be used for color toner. Glycol having an aromatic structure such as bisphenol A alkylene oxide adduct represented by the formula (1) has a lower esterification reaction rate than glycol having an alicyclic structure such as cyclohexanedimethanol, and thus has a high temperature (240 ° C.). Above ℃)
In addition, the glycol having an aromatic structure is not stable at high temperature, and is considered to be partially decomposed and deteriorated to cause coloration.

1,4-cyclohexanedimethanol is 3
When the content is 5 mol% or more and 65 mol% or less, the reaction rate is relatively high, the reaction can be carried out at a relatively low temperature (around 230 ° C.), and the thermal stability is good. Color toner having good hue can be obtained.

The degree of alteration and coloring of the resin itself is indicated by the Gardner color number. The polyester resin for a color toner in the present invention preferably has a Gardner color number of 2 or less, more preferably 1 or less.

In producing the polyester for a color toner according to the present invention, the above-mentioned various raw materials other than the main monomer raw materials such as cyclohexane dimethanol, an adduct of bisphenol A alkylene oxide and terephthalic acid are used without departing from the scope of the present invention. However, raw materials that cause coloring of the resin, for example, polyhydric alcohols, polybasic acids, or polyamines and polyisocyanates containing a nitrogen atom are not preferred.

The polybasic acid component constituting the polyester resin in the present invention contains terephthalic acid or its lower alkyl ester as a main component from the viewpoint of heat cohesion. Other polybasic acids that can be used in combination with terephthalic acid include
For example, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecenylsuccinic acid, n-dodecylsuccinic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, cyclohexanedicarboxylic acid,
Dibasic acids such as orthophthalic acid, isophthalic acid, etc .; acids having three or more bases such as trimellitic acid, trimetic acid, and pyromellitic acid; and anhydrides and lower alkyl esters thereof. It is possible to use a small amount together.

The glass transition point of the polyester resin for a color in the present invention is preferably 55 to 75 ° C, more preferably 60 to 70 ° C. Glass transition point is 55
If the temperature is lower than ℃, the heat cohesion of the toner becomes poor, and if it exceeds 75 ° C, the fixability becomes poor.

The melt viscosity of the polyester resin for color in the present invention at 100 ° C. is preferably 10 ⁴ to 10 ⁶ poise, more preferably 5 × 10 ^{4 to} 5 × 1.
0 ⁵ poise. If the melt viscosity at 100 ° C. is less than 10 ⁴ poise, paper wrapping and offset phenomenon are likely to occur, depending on the amount of silicone oil supplied to the fixing heat roll. On the other hand, if it exceeds 10 ⁶ poise, the melting and mixing of the cyan, magenta, yellow, and black toners transferred onto the paper at the time of fixing becomes incomplete, resulting in poor coloring.

The ring and ball softening point SP of the polyester resin for a color in the present invention is preferably from 90 to 120 ° C, more preferably from 95 to 115 ° C. Softening point 9
If the temperature is lower than 0 ° C., depending on the supply amount of the silicone oil to the fixing heat roll, paper wrapping and offset phenomenon are likely to occur. Conversely, if the temperature exceeds 120 ° C., the melting and mixing of the cyan, magenta, yellow, and black toners transferred onto the paper at the time of fixing becomes incomplete, resulting in poor coloring.

The weight average molecular weight of the polyester resin for a color in the present invention is preferably from 5,000 to 20,000, more preferably from 7000 to 12,000. If the weight average molecular weight is less than 5,000, the resin becomes too brittle, and a large amount of fine powder of 2 μm or less is produced at the time of pulverization into toner, and the classification yield is reduced. Conversely, if the weight average molecular weight exceeds 20,000, the resin becomes too tough, and the pulverizability (productivity) of the toner decreases.

The polyester resin of the present invention has an acid value of 30 mg · KOH / g or less and a hydroxyl value of 60 mg · KO.
H / g or less is preferable. The polyester resin in the present invention is produced by a usual polyester synthesis method, that is, a polybasic acid component and a polyhydric alcohol component are subjected to an esterification reaction or a transesterification reaction, and condensed water, a low-boiling alcohol component, and the like are distilled out of the system. It is synthesized by a method of condensation.

For the polycondensation, known polymerization catalysts such as titanium tetrabutoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, germanium dioxide and the like can be used.

The polyester resin in the present invention is preferably used alone, but may be blended with other resins such as a styrene acrylic resin, an epoxy resin, a polyester resin, a petroleum resin and the like without departing from the object of the present invention. It is also possible to use.

The method for producing toner using the polyester resin in the present invention and examples of toner blending will be described. First, the binder resin according to the present invention is pulverized, a coloring agent, a charge control agent for adjusting triboelectricity and the like are added and premixed, and extruder, after melt-kneading with a pressure kneader or the like, The powder is pulverized and classified, and finally a fluidity improver such as silica fine powder is dry-blended to obtain a toner.

As the coloring agent, for example, the following can be used alone or in combination. Examples of the yellow pigment include C.I. I. NO. C. I. Pigment name Chemical structure Pig. NO. 21127 Y-81 KET yellow 401 insoluble disazo Y-154 KET yellow 402 benzimidazolone 21105 Y-17 KET yellow 403 insoluble disazo 21095 Y-14 KET yellow 404 insoluble disazo 21100Y13 yellow Yazo 21100 Y-210 15865: 3 R-48-3 KET Red 305 Azo lake 15850: 3 R-57-1 KET Red 306 Azo lake 15850: 3 R-57-1 KET Red 307 Azo lake 12360 R-31 KET as the KET yellow 406 insoluble disazo magenta pigment. Red 308 Azo Lake 73915 R-122 KET Red 309 quinacridone cyan pigment Is 74160 B-15-6 KET Blue 102 phthalocyanine-based 74160 B-15 KET Blue 103 〃 74160 B-15-3 KET Blue 104 〃 74160 B-15-4 KET Blue 105 ７４ 74160 B-15-4 KE106 Bu B-68 KET Blue 107}, and C.I. I. Pigment Red 5,
C. I. Pigment Red 6, C.I. I. Pigm
ent Red 207, C.I. I. PigmentYe
low 15, C.I. I. Pigment Blue 1
6 and the like. However, it is not limited to these.

Of these, KET series pigments are available from Dainippon Ink and Chemicals, Inc. Examples of oil-soluble dyes include C.I. I. Solvent Red 24 C.I. I. Solvent Violet 13 C.I. I. Solvent Blue 7 C.I. I. Solvent Blue 35 C.I. I. Solvent Brown 5 C.I. I. Solvent Yellow 2 C.I. I. Solvent Yellow 14 C.I. I. Solvent Orange 7 C.I. I. Solvent Red 3 and the like.

As the charge control agent, a metal complex compound of salicylic acid or an ester of salicylic acid and an alkyl alcohol, an electron-accepting metal complex, etc. may be used to give a negative charge, but the polyester resin itself of the present invention has a negative charge. Since it has a charging property, it is not always essential. Alcooxylated amines, quaternary ammonium salts, alkylamides, and the like are used to give a positive charge.

As the offset resistance improver, in the case of a conventional black toner, a low molecular weight polyolefin such as a polypropylene wax or a polyethylene wax is usually preferably used. It is not preferable as a raw material of the toner. This is because low-molecular-weight polyolefins generally have poor compatibility with polyester and impair transparency.

[0039]

The present invention will be described below in detail with reference to Examples and Comparative Examples. The parts in the examples are on a weight basis.

(Synthesis Example 1) In a flask having a stirrer, a thermometer, an N ₂ gas introducing tube, and a fractionating tube, 576 parts (corresponding to 4 mol) of cyclohexanedimethanol and bisphenol A were added.
2.2 mol adduct of ethylene oxide 1950 parts (6
Mol), then 1461 parts of terephthalic acid (8.8
Mol) and 4 parts of dibutyltin oxide.
_The mixture was heated with stirring and heated under a stream of _two gases, and a dehydration condensation reaction was performed at 240 ° C. At that time, care was taken not to distill out the raw material monomer, and if distilling out, the distillate was compensated for and adjusted so as to obtain a resin composition according to the charged composition. Acid value is 5mg
-The reaction was performed until the KOH / g was reached, and the reaction mixture was taken out to obtain a solid polyester resin.

(Synthesis Examples 2 to 4, Comparative Synthesis Examples 1 to 3) A polyester resin was synthesized in the same manner as in Synthesis Example 1. Table 1 shows the raw material compositions used in Synthesis Examples and Comparative Synthesis Examples, and Tables 2 and 3 show the physical property values of the obtained polyester resins.

The measurement of each physical property value was carried out by a conventional method as follows. * Ring and ball softening point: Measured using a ring and ball type automatic softening point tester 25D5-ASP-M4SP manufactured by Meikyousha Seisakusho. * Glass transition temperature: Measured according to JIS K-7121 using a differential scanning calorimeter DSC220C manufactured by Seiko Denshi Kogyo. * Melting viscosity: Flow tester CFT-5 manufactured by Shimadzu Corporation
Using No. 00, the measurement was performed at a nozzle diameter of 0.5 mm, a nozzle length of 1 mm, a load of 80 kg, and a temperature rising rate of 5 ° C./min. * Weight average molecular weight: Tosoh GPC measuring instrument HLC-8
020 and the column is TSK-G-5000 manufactured by Tosoh
HXL, 4000HXL, 3000HXL, 2000H
4 XL. Measured with 0.3 W / V% THF solution. The calibration curve was made with standard polystyrene. * Haze value: Measured with a test piece having a diameter of 45 mm and a thickness of 7 mm using an integrating sphere light transmittance measuring device (full automatic direct reading haze meter HGM-20P) manufactured by Suga Test Instruments. Haze value (H) is diffuse transmittance (Td) and total transmittance (Tt)
Is displayed in the ratio of H = Td / Tt × 100% * Gardner color number: It was measured according to ASTM D-154-58 using a Gardner-Heliege colorimeter.

[0043]

[Table 1] (Note) The numerical values indicate the number of moles.

CHDM: 1,4-cyclohexanedimethanol NPG: neopentyl glycol BPAEO: bisphenol A ethylene oxide
2 mol adduct BPAPO: bisphenol A propylene oxide 2.2 mol adduct TPA: terephthalic acid TMAn: trimellitic anhydride

[0045]

[Table 2] In the table, rapid cooling means cooling at 100 ° C./min or more, and slow cooling means cooling at 0.1 ° C./min or less.

(Examples 1 to 3, Comparative Examples 1 to 3) Synthesis Example 1
Using the polyester resins obtained in Comparative Examples 1 to 3 and Comparative Synthesis Examples 1 to 3, color toners were prepared in the following manner.

The cyan toner is used in an amount of KET Blue 103 (CI Pigmen) based on 100 parts of the binder resin.
t Blue 15) 5 parts and Bontron E-84 (Orient Chemical's charge control agent) 3 parts were mixed, melt-kneaded with a heating roll, pulverized with a jet mill, and classified and collected with a particle diameter of 5 to 15 μm. Aerosil R-972 (Nippon Aerosil hydrophobized silica) 0.4 parts externally added and average particle size 10μ
m cyan toner was obtained. Toners of other colors were prepared in exactly the same manner except that the amount of the color pigment and the amount thereof were changed.
That is, magenta toner is KET Red 309
(CI Pigment Red 122) in 3 parts,
Yellow toner is KET Yellow 403 (C.I.
I. Pigment Yellow 17) is 4 parts, and black toner is KET Yellow 403 as 1.2 parts.
Part, C.I. I. Pigment Red6 2.7 parts,
C. I. Pigment Blue 16 in an amount of 1.1 parts.

A developer was prepared by mixing 5 parts of the obtained color toner and 95 parts of a ferrite carrier coated with a styrene acrylic resin, and a commercially available color electrophotographic copying machine (silicon oil coated type heat fixing device built-in) ) Was performed to obtain an image.

Table 4 shows the results. In all the cases, if ○ or な ら, it is applicable as the color toner of the invention. The measurement of each physical property value was performed as follows by a conventional method. * Heat-resistant aggregation property: 20 g of the toner was placed in a 100-cc sample bottle, left standing in a hot-air dryer at 50 ° C. for 24 hours, the bottle was turned upside down and spread on paper, and the aggregation block was observed and evaluated. * Fixing property: A solid surface developed with a cyan toner was subjected to a peeling test using cellophane tape. * Offset resistance: The belt-like solid surface was continuously developed with cyan toner, and it was checked whether an offset image was generated, whether the roll was dirty, and whether the paper was wrapped. * Evaluation of color development: flatness of toner-fixed image and reproducibility of intermediate colors were visually judged using all color toners of cyan, magenta, yellow and black, and using a standard color original.

[0050]

[Table 3] *: Cannot be measured due to insolubility in solvents such as THF **: Cannot be measured due to cloudiness ***: Does not flow out at 100 ° C

[0051]

[Table 4] Heat-resistant cohesion: ◎: Almost no coagulation block. ：: Slight, but easy to loosen. Δ: Slightly large and difficult to loosen. ×: A considerably hard block. XX: Does not come out of the bottle. Fixing property: A: Almost no adhesion to cellophane tape. ：: Slightly adhered to cellophane tape. Δ: about 30% adhered to cellophane tape. X: about 60% adhesion.

XX: Mostly peeled. Offset resistance: ： １: No problem with 10,000 sheets or more. ×:
The offset phenomenon appears up to 10,000 sheets.

Coloring property: A: extremely excellent ○:
Are better. Δ: slightly dissatisfied. ×:
Clearly poor color reproduction.

[0054]

By using the polyester resin of the present invention as a binder resin, color development, heat cohesion, fixability,
A color toner having excellent offset resistance can be obtained.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-9278 (JP, A) JP-A-4-239022 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/08

Claims (1)

(57) [Claims] 1. A polybasic acid component comprising terephthalic acid as a main component, and a polyhydric alcohol component comprising 1,4-cyclohexanedimethanol (A) and glycol (B) represented by the following formula (1). Wherein the molar ratio of (A) :( B) is 35:65 to 65:35, and the polyhydric alcohol component
90% by mole or more of the total of (A) and (B)
The glass transition temperature Tg is 55 to 75 ° C, the weight average molecular weight Mw is 5,000 to 20,000, the melt viscosity at 100 ° C is 10 ⁴ to 10 ⁶ poise, and the ring method softening point SP is 90 to 90.
A color toner for developing an electrostatic image, comprising a polyester resin as a binder resin at 120 ° C. Embedded image (Wherein, R is an alkylene group having 2 or 3 carbon atoms,
m and n are integers and 2 ≦ m + n ≦ 4. )