JPH1115199A - Resin for electrophotographic toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the resin for the electrophotographic toner superior in low temperature fixability and offset resistance and also in durability against successive copyings. SOLUTION: This toner resin is prepared by polymerizing a mono-epoxy compound alone or a polyepoxy compound having 2-4 epoxy groups and the monoepoxy compound with an unsaturated dibasic acid, and further polymerizing this obtained product by heating or in the presence of a polymerization initiator, and the obtained polymer is solid at normal temperature and has a ratio of a weight average molecular weight to a number average molecular weight >=5 and a softening point measured by the ring and ball method is 90 deg.C-200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin for an electrophotographic toner having excellent low-temperature fixability and offset resistance, and also having excellent durability in continuous copying.

[0002]

2. Description of the Related Art In electrophotography, an electrostatic image is formed on a photoreceptor by various means, the electrostatic image is developed with dry toner, and then the toner is transferred to a transfer material such as paper. It is fixed by a heat roller fixing method. There are the following two types of toner for developing an electrostatic image.

[0003] 1) A dry toner is mixed with a carrier having a particle diameter larger than that of the toner, and a charge opposite to that of the electrostatic latent image is given to the toner by triboelectric charging. A two-component toner that brings an agent into contact with an electrostatic latent image and develops the electrostatic latent image.

[0004] 2) A one-component toner in which a relatively low- or high-resistance toner containing a magnetic material is brought into contact with an electrostatic latent image or is developed close to the electrostatic latent image. Conventionally, to obtain these toners, a toner resin is melted, and a coloring agent such as a dye or a pigment, a magnetic material, a triboelectric charge controlling agent, an offset preventing agent, a lubricating oil, etc. are added to the resin, and then mixed sufficiently. A method of solidifying by cooling, pulverizing the mixture, and classifying the mixture to obtain particles having a required particle size has been implemented.

[0005] By the way, with the development of the information society in recent years,
In the field of electrophotography, demands for higher quality of images, higher speed of recording, long-term preservation of recording, and the like are increasing, and demands for improvement of characteristics of toner used in developing an electrostatic latent image are increasing. In some cases, such an improvement in characteristics depends on the toner resin used, and there is a demand for the improvement.

Conventionally, a styrene-based resin represented by a styrene-acryl copolymer, a polyester resin, or the like has been used as this type of resin. In the case of a styrene-based resin, it is necessary to increase the softening point and the crosslinking density of the resin in order to improve the offset resistance, but this deteriorates the low-temperature fixability.
Conversely, if the emphasis is placed on the low-temperature fixability, problems occur in the offset resistance and the blocking resistance. In addition, when paraffin wax, low molecular weight polyolefin, or the like is added as an anti-offset agent, if the added amount is too small, the effect cannot be obtained, and if it is too large, there is a problem that the developer deteriorates immediately. In the case of a polyester resin, generally, the fixing property is excellent, but at the time of fixing, a part of the toner constituting the image is transferred to the surface of the heat roller, and is transferred again to the next transfer paper or the like to stain the image. However, there is a disadvantage that offset development is easily generated, and if this defect is improved, the fixability is impaired, and none satisfying these characteristics at the same time has been obtained.

For this reason, attempts have been made to use a styrenic resin and a polyester resin having excellent fixing properties in combination. However, since the styrenic resin and the polyester resin are inherently poor in compatibility, it is difficult to prepare a toner. In this case, the dispersion of the resin and the internal additives such as carbon black becomes worse, the charging property becomes non-uniform, and adverse effects such as background contamination occur in image evaluation. Further, when the molecular weights of the resins are different, a difference occurs between the two melt viscosities, and it becomes difficult to reduce the dispersed particle diameter of the resin in the dispersed phase.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a resin for electrophotographic toner which is excellent in low-temperature fixability and offset resistance and also excellent in durability in continuous copying.

[0009]

That is, the present invention relates to a monoepoxy compound alone or a monoepoxy compound and 2 to 4 monoepoxy compounds.
Polyester resin containing a polyepoxy compound having an epoxy group and an unsaturated dibasic acid as raw material monomers,
It is further polymerized in the presence of heating or a polymerization initiator,
It is a solid at room temperature and the ratio of the weight average molecular weight to the number average molecular weight is 5
As described above, the present invention provides an electrophotographic toner resin having a softening point (ring and ball method) of 90 to 200 ° C.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The monoepoxy compounds used in the present invention include, for example, phenylglycidyl ether, alkylphenylglycidyl ether, alkylglycidyl ether, alkylglycidyl ester, glycidyl ether of alkylphenol alkylene oxide adduct, α-olefin oxide, Epoxy fatty acid alkyl esters and the like are listed.

The alkylphenyl glycidyl ether includes, for example, cresyl glycidyl ether, butyl glycidyl ether, nonyl glycidyl ether and the like. Examples of the alkyl glycidyl ether include butyl glycidyl ether and 2-ethylhexyl glycidyl ether.

The alkyl glycidyl ester includes

[0013]

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(Where R is an alkyl group having 1 to 2 carbon atoms)
5, preferably 10 to 15. ). The glycidyl ether of an alkylphenol alkylene oxide adduct is, for example, a glycidyl ether of an adduct of an alkylene oxide such as ethylene oxide and propylene oxide to a lower alkylphenol such as butylphenol, and a glycidyl ether of ethylene glycol monophenyl ether and polyethylene glycol monophenyl ether. Glycidyl ether, glycidyl ether of propylene glycol monophenyl ether, glycidyl ether of polypropylene glycol monophenyl ether, propylene glycol mono (pt-
Butyl) phenyl ether glycidyl ether; ethylene glycol monononyl phenyl ether glycidyl ether;

Examples of the α-olefin oxide include alpha-olefin oxide-168 [product of Adeka Argus Chemical Co., Ltd.] and alpha-olefin oxide.
Oxygenated compounds of olefins such as -124 [product of Adeka Argus Chemical Co., Ltd.].

The monoepoxy fatty acid alkyl ester is a compound obtained by epoxidizing an unsaturated group of an alcohol ester of an unsaturated fatty acid, for example, epoxidized butyl oleate.

[0017]

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Epoxy octyl oleate and the like can be mentioned. Examples of the polyepoxy compound having 2 to 4 epoxy groups include bisphenol A type epoxy resin, novolak type epoxy resin, ethylene glycol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, and trimethylolethane triglycidyl. Examples include one or more of ether, pentaerythritol tetraglycidyl ether, hydroquinone diglycidyl ether, and a semi-dry or dry fatty acid ester epoxy compound. Among these, bisphenol A type epoxy resin is preferable from the viewpoint of plasticizer resistance.

The unsaturated dibasic acids include maleic acid, maleic anhydride, fumaric acid, tetrahydrophthalic acid,
Examples include tetrahydrophthalic anhydride, itaconic acid, mesaconic acid, citraconic acid and the like.

In the present invention, the polyester resin is
A polyester resin obtained by polycondensing a monoepoxy compound alone or a monoepoxy compound and a polyepoxy compound having 2 to 4 epoxy groups with a dibasic acid and a polyol, and a part or a part of the dibasic acid It is a polyester resin containing an unsaturated dibasic acid in all.

Representative examples of the dibasic acid component include orthophthalic acid, isophthalic acid, terephthalic acid, phthalic anhydride, succinic acid, adipic acid, oxalic acid, malonic acid, sebacic acid and the like.

The polyols include ethylene glycol, 1,2 propylene glycol, 1,3 propylene glycol, 1,3 butylene glycol, 1,4 butylene glycol, 1,6 hexanediol, neopentyl glycol, dipropylene glycol, diethylene glycol, Examples include hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, and bisphenol A propylene oxide adduct.

Further, as a raw material of the polyester resin,
Trifunctional compounds such as trimetic anhydride, glycerin, trimethylolethane, and trimethylolpropane, and polyfunctional compounds such as ethylene oxide adducts of phenol novolak and propylene oxide of phenol novolak can also be used in combination.

The polyesterification reaction is one which is arbitrarily produced by a known polycondensation reaction method. For example, in the presence of an esterification catalyst (dibutyltin oxide, tetrabutyl titanate, paratoluenesulfonic acid, etc.) or in the presence of a transesterification catalyst (lead compound, tin compound, tetrapropyl titanate, etc.), lower carboxylic acids such as methyl dicarboxylate are used. It may be carried out by any production method such as a transesterification reaction using an alkyl ester, a normal pressure dehydration reaction, a reduced pressure, a vacuum dehydration reaction, a solution polycondensation method, and a solid phase polycondensation reaction method.

The tracing of the polyesterification reaction is carried out by measuring the acid value, hydroxyl value, viscosity or softening point (ring and ball method). The polyester resin thus obtained is
The polymerization reaction is further advanced by heating or in the presence of a polymerization initiator. In the case of heating, it is 3 to 15 at a temperature of 230 to 260 ° C.
About 130-250 in the presence of a polymerization initiator
The reaction is carried out at a temperature of 0.5C for about 0.5 to 15 hours. Examples of the polymerization initiator include tertiary butyl hydroperoxide, cumene hydroperoxide, ditertiary butyl peroxide, tertiary butyl peroxybenzoate, dicumyl peroxide, tertiary butyl cumyl peroxide, and the like.
The amount of the polymerization initiator is 0.01% of the polyester resin.
-5% by weight, preferably 0.02-2% by weight.

The polymer of the polyester resin obtained by the above method has a ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of 5 or more, preferably in the range of 15 to 50. is there. When Mw / Mn is less than 5, offset is likely to occur and the effect is small.

The number average molecular weight of the polyester resin before polymerization is not particularly limited, but is preferably 4100 or more. When it is less than 4100, it is very difficult to make the ratio of the weight average molecular weight to the number average molecular weight 15 or more by polymerization.

In the present invention, the values of the weight average molecular weight and the number average molecular weight were measured under the following measurement conditions. GPC apparatus: Tosoh Corp. HLC-8120GPC COLUMN: Tosoh Corp. TSK-GEL G-5000HXL G-4000HXL G-3000HXL G-2000HXL Solvent: Tetrahydrofuran Flow rate: 1.0 ML / MIN according to the present invention In order for the resin for photographic toner to maintain its properties, the softening point (ring and ball method) is 90 to 200 ° C.
Preferably it is 110-150 degreeC. Softening point 9
When the temperature is lower than 0 ° C., when the temperature is high such as in summer, toner aggregation phenomenon occurs, causing a copying trouble. When the temperature is higher than 200 ° C., the low-temperature fixability deteriorates.

A toner is prepared by adding a coloring agent such as a dye or a pigment, and if necessary, a magnetic substance, a triboelectric charge controlling agent, an offset preventing agent, and a lubricating oil to the resin for an electrophotographic toner of the present invention. This toner has good fixability at low temperature or high speed, and has excellent performance in which an offset phenomenon to a heating roll does not occur.

[0030]

EXAMPLES Examples of the present invention will be described in detail below, but the present invention is not limited to these examples. Unless otherwise specified in the text, it is based on weight.

Examples 1 to 5 956 g of polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, Cardura E
(Shell Japan products, alkyl glycidyl esters)
150 g, 448 g of terephthalic acid, 29 maleic anhydride
g and 1.6 g of dibutyltin oxide were placed in a glass two-liter four-necked flask, and the temperature was gradually raised under a nitrogen stream, followed by a reaction at 240 ° C. for 10 hours. This polyester resin had an acid value of 10 and a number average molecular weight of 4,300.
Further, the temperature of the resin was lowered to 180 ° C., 5 g of di-tert-butyl peroxide was added, and the mixture was stirred for 30 minutes. Then, the temperature was raised to 240 ° C., and the mixture was further stirred for 3 hours to further polymerize, thereby obtaining a resin for toner. The resulting resin was a solid at room temperature, and had an acid value of 4, a glass transition temperature of 64 ° C by DSC measurement, and a softening point (ring and ball method) of 130 ° C. The results of measuring the molecular weight distribution were as follows: Mw = 123000, Mn = 4400, Mw / Mn
= 28.

A resin for an electrophotographic toner was produced by the method shown in Tables 1 and 2 in the same manner as in Example 1.

[0033]

[Table 1]

[0034]

[Table 2]

The abbreviations in the table are as follows. BPA-PO: bisphenol A propylene oxide 2.2 mol adduct BPA-EO: bisphenol A propylene oxide 2 mol adduct E-850: bisphenol A type epoxy resin manufactured by Dainippon Ink and Chemicals, Inc. BGE: butyl glycidyl ether Cardura E: alkyl glycidyl ester manufactured by Shell Japan K.K. NPG: neopentyl glycol EG: ethylene glycol TPA: terephthalic acid MA: maleic anhydride IPA: isophthalic acid FA: fumaric acid TMP: trimethylolpropane Comparative Example 1 maleic anhydride Instead, an electrophotographic toner resin was produced in exactly the same manner as in Production Example 1, except that the same mole of phthalic anhydride was used.

The resin obtained had an acid value of 5, a glass transition temperature of 63 ° C., a softening point of 113 ° C., Mw = 13760, and Mn = 5.
4300, Mw / Mn = 3.2. Comparative Example 2 Electrophotography was performed in exactly the same manner as in Example 1 except that polyoxypropylene- (2.2) -bis (4-hydroxyphenyl) propane was increased by an equivalent amount thereof without using Cardura E. A resin for toner was manufactured.

The obtained resin had an acid value of 4, a glass transition temperature of 65 ° C., a softening point of 132 ° C., Mw = 137600, and Mn of
= 4300 and Mw / Mn = 32. Application Example 90 parts by weight of the resin obtained in Example 1, 5 parts by weight of carbon black MA-11 (Mitsubishi Chemical), 1.5 parts by weight of Bontron E-81 (charge control agent manufactured by Orient Chemical), Viscol 550P (Sanyo) 3.5 parts by weight of a polypropylene wax (manufactured by Kasei Co., Ltd.) were mixed by a super mixer, melt-kneaded in a pressure kneader, cooled and then pulverized and classified by a jet mill to obtain a toner having an average particle diameter of 12 μm. 7 parts by weight of the obtained toner were mixed with 93 parts of iron powder carrier and mixed developer, and an image was formed with a commercially available electronic copying machine. A fixing test was performed with a heat roller fixing device at a speed of 280 mm / sec. As a result, no offset occurs up to 245 ° C., the minimum fixing temperature is 130 ° C., no fogging occurs even in continuous copying of 50,000 sheets, and 10,000 sheets of continuous printing are performed at a temperature of 35 ° C. and a humidity of 85%. A clear image was obtained in the copy.

The same procedure was carried out using the resins for electrophotographic toners of Examples 2 to 5 and Comparative Examples 1 and 2 shown in Tables 1 and 2 in exactly the same manner. The performance evaluation is shown in Table 3.

[0039]

[Table 3]

As can be seen from Table 3, the toner of the present invention is particularly superior in low-temperature fixability, anti-offset performance, and durability in continuous copying as compared with the conventional polyester toner (comparative example). Was observed.

[0041]

The resin for electrophotographic toner of the present invention has excellent low-temperature fixability and offset resistance, and also has excellent durability in continuous copying.

Claims (3)

[Claims] 1. A polyester resin containing a monoepoxy compound alone or a monoepoxy compound, a polyepoxy compound having 2 to 4 epoxy groups and an unsaturated dibasic acid as raw material monomers is heated or heated in the presence of a polymerization initiator. A solid at room temperature, a ratio of the weight average molecular weight to the number average molecular weight of 5 or more, and a softening point (ring and ball method) of 9
A resin for an electrophotographic toner, which has a temperature of 0 to 200 ° C. 2. A polyester resin having a number average molecular weight of 41.
The resin for an electrophotographic toner according to claim 1, which has a molecular weight of 00 or more. 3. The method of claim 1, wherein the ratio of the weight average molecular weight to the number average molecular weight is 1
3. The resin for an electrophotographic toner according to claim 1, wherein the number is from 5 to 50. 4.