JPH0772808B2 - Binder for toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a toner preparation used for developing an electrostatic image formed in electrophotography, electrostatic photography, electrostatic recording or the like. Regarding the binder.

[Prior Art] Generally, an electrostatic image is developed with a toner which is a colored powder to form a toner image, and the toner image is fixed as it is or after being transferred onto a transfer paper or the like.

Then, the toner is usually prepared by melting and mixing a composition composed of a polymer as a binder component, a coloring agent such as carbon black, and a composition containing a charge control agent as a main component under application of force.

Conventionally, styrene-based resins have been mainly used as the above-mentioned binder component, but recently, a saturated polyester resin suitable for high-speed copying, which has a large negative chargeability and excellent low-temperature fixability, has been attracting attention, and many studies have been conducted. Has been done.

[Problems to be Solved by the Invention] The inventors of the present invention have repeatedly studied polyester-based resin toner binders, and have invented that there is a problem that an offset phenomenon occurs. That is, a part of the toner substance is transferred to the heat roller and stains the surface of the transfer paper supplied thereafter, or the back surface of the transfer paper is soiled by the toner substance transferred to the pressing roller pressed by the heat roller. It is done.

Therefore, originally, the fixing property and the offset preventing property are contradictory required physical properties, but it is absolutely necessary to prevent the occurrence of the offset phenomenon while maintaining the low temperature fixing property which is the characteristic of the polyester resin toner, in practical use of the toner. This is a task that must be done.

The present inventors have conducted research based on the finding that it is necessary to give a crosslinked structure to a polyester resin for such a solution, and first tried to make a crosslinkable compound coexist during the production of the polyester resin. It is not practical because it requires high-speed technology to control the reaction. Furthermore, various crosslinking agents such as epoxy type, metal chelate type, peroxide type, sulfur compound type and oxime type are used during melt mixing during toner preparation. Then, the polyester resin was post-crosslinked, but in any case, the problem could not be solved.

[Means for Solving Problems] As a result of further research by the present inventors, a glass transition temperature of 30
Saturated polyester resin 100 with acid value of 10KOHmg / g or more at ~ 70 ℃
The inventors have found that a composition obtained by blending 1 to 20 parts by weight of maleimide prepolymer in parts by weight meets the purpose, and completed the present invention.

The saturated polyester resin of the present invention is obtained by condensing any acid component and polyhydric alcohol component. Such acid components include terephthalic acid, isophthalic acid, malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, azelaic acid, sebacic acid, 1,3-Cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, 1,4-naphthalic acid, diphenine Acid, 4,4'-oxybenzoic acid, diglycolic acid, thiodipropion, and 2,
Examples include 5-naphthalenedicarboxylic acid.

These may be acid anhydrides, esters, chlorides and the like and include, for example, dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 2,6-naphthalenedicarboxylate, dimethyl isophthalate, dimethyl terephthalate and diphenyl terephthalate.

In addition to the above, small amounts of (anhydrous) maleic acid, fumaric acid,
Unsaturated carboxylic acids such as itaconic acid and polyvalent carboxylic acids having a valence of 3 or more, such as trimellitic acid and trimellitic anhydride,
Pyromellitic acid, pyromellitic dianhydride, 4-methylcyclohexene-1,2,3 tricarboxylic acid anhydride, trimesic acid and the like can also be used.

Further, as the polyhydric alcohol, ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-
1,3-diol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3 -Propanediol, 1,3-butanediol,
1,4-butanediol, 1,5-pentanediol, 1,6-
Hexanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,6-hexanediol, 1,2
-Cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,
2,4,4-tetramethyl-1,3-cyclobutanediol, 4,
4'-thiodiphenol, 4,4'-methylenediphenol, 4,4 '-(2-norbornylidene) diphenol,
4,4'-dihydroxybiphenol, o-, m- and p-
Examples include dihydroxybenzene, 4,4'-isopropylidenephenol, 4,4'-isopropylidenebis (2,6-dichlorophenol), 2,5-naphthalenediol and p-xylediol, and cyclohexanedimethanol.

In addition to the above, trihydric or higher polyhydric alcohols such as pentaerythritol, dipentaerythritol, tripentaerythritol, glycerin, trimethylolpropane, trimethylolethane, 1,3,6-hexanetriol can be used in a small amount. is there.

In addition to the above acid component and polyhydric alcohol component, a sulfonate group can be introduced into the resin by a generally known method. Typical examples of the condensation component used in this case include 5-sodiosulfoisophthalic acid and 5-potassium sulfoisophthalic acid, but the condensation component is not limited thereto.

No special operation is required to produce a polyester resin by condensing the acid component and the polyhydric alcohol component,
Any conventionally known method may be used, but a typical example is to charge a reactor with a polyhydric alcohol component in an amount of 1.0 to 1.5 times the amount of an acid component together with a catalyst, and raise the temperature to 140 to 280 ° C to perform dehydration condensation. I do. The catalyst used in this case is zinc acetate,
Zinc chloride, stannous lauryl, dibutyltin oxide, etc. are used, and these are usually 0.05 to 0 relative to dicarboxylic acid.
15% by weight is charged. A solvent is not particularly required, but if necessary, an inert solvent such as methyl acetate, benzene, acetone, xylene, toluene may be used.

The polyester resin has a glass transition temperature of 30 to 70 ° C, preferably 45 to 75 ° C and an acid value of 10 KOHmg / g or more, preferably 2
Must be 0-60 KOHmg / g. 3,00 as the molecular weight
0 to 8,000 is desirable.

When the glass transition temperature is 30 ° C or lower, the storage stability of the toner becomes poor, and when the glass transition temperature is 70 ° C or higher, the fixing temperature becomes high, and neither is practical.

Further, when the acid value is 10 KOHmg / g or less, the effect of improving offset development is not recognized, and it is not suitable for use.

Next, the maleimide prepolymer used in the present invention means the following general formula containing two or more maleimide groups derived from polyamine and maleic anhydride. It is a reaction product of one or more reaction products of the compound represented by or a compound containing two or more maleimide groups with a cyanate ester or a cyanate ester prepolymer.

In the formula, n is an integer of 2 or 3, R is a divalent or trivalent aromatic or alicyclic organic residue, for example, a benzene ring, a naphthalene ring, an anthracene ring, diphenyl, diphenylalkane, diphenyl ether. , Diphenylsulfonyl, diphenylcarbonyl, cyclohexane ring, hexahydroxyrylene ring and the like.

Bismaleimide is preferably used. Diamines used to prepare bismaleimides include, for example, metaphenylenediamine, meta or para-xylylenediamine, 1,4-cyclohexanediamine, hexahydroxylylenediamine, 4,4'-bisaminophenylmethane, 4 , 4'-bisaminophenyl sulfone, bis (4-
Amino-3-methylphenyl) methane, bis (4-amino-3,5-dimethylphenyl) methane, 4,4'-bisaminophenylcyclohexane, 4,4'-bisaminophenyl ether, 2,2-bis ( 4'-aminophenyl) propane, 2,2-bis (4-amino-3-methylphenyl)
Examples include methane and α, α-bis (4-aminophenyl) phenylmethane.

On the other hand, the cyanate ester is a compound represented by the general formula R ₁ O—C≡N) _m having two or more cyanate ester groups. In the formula, m is an integer of 2 to 5, R ₁ is an aromatic bridge-bonding group, and the cyanate ester group is bonded to the aromatic nucleus represented by R ₁ . Examples of R ₁ include a group in which a ring, which is the same organic residue as that of R described above, is bonded at a cross-linking portion, and an organic group forming a skeleton of a novolac type phenol resin. Other specific examples are disclosed in, for example, Japanese Patent Publication No. 52-31279.

The cyanate ester prepolymer is a prepolymer obtained by polymerizing the above cyanate ester in the presence of a catalyst.
These prepoimers generally have in the molecule a triazine ring formed by trimerizing the cyano group in the cyanate ester.

Examples of the maleimide prepolymer preferably used in the present invention include bismaleimide triazine resin (BT resin) manufactured by Mitsubishi Gas Chemical Co., Inc.

In the present invention, the maleimide prepolymer should be blended in an amount of 1 to 20 parts by weight, preferably 1 to 15 parts by weight, based on 100 parts by weight of the saturated polyester resin.

If it is 1 part by weight or less, the effect of the present invention is difficult to obtain, while if it is 20 parts by weight or more, the flow starting temperature of the composition becomes high, the low temperature fixing property is poor and the practicality is poor.

In preparing the toner, the saturated polyester resin composition, the colorant and, if necessary, the charge control agent may be melt mixed.

As a colorant, carbon black, nigrosine dye, aniline blue, chalco oil blue, chrome yellow,
Examples include ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachide green oxalate, lamp black and rose bengal.

If necessary, a known auxiliary agent other than the saturated polyester resin of the present invention, a wax, polyethylene, or the like may be added during toner preparation.

The effect of the present invention is that by subjecting the saturated polyester resin to a heat treatment during the production (at the time of melting) of the toner, the saturated polyester resin has a suitable elasticity because the maleimide prepolymer causes cross-linking. It also contributes to the prevention of the offset phenomenon while maintaining the fixing property in the above.

[Operation] The crosslinked polyester resin of the present invention is particularly useful as a toner binder for electrophotography.

[Examples] Next, the binder of the present invention will be described with reference to examples.

"Parts" indicate weight standards.

Example 1 0.5 mol of terephthalic acid, 0.5 mol of isophthalic acid, 1.0 mol of ethylene glycol, 0.3 mol of neopentyl glycol in the presence of a dibutyltin oxide catalyst in a nitrogen atmosphere.
The reaction was carried out at 220 ° C. until no runoff water was generated. Next, 0.25 mol of trimellitic anhydride was charged and the reaction was stopped when the reaction product became transparent.

The obtained saturated polyester resin has an acid value of 52.6 KOHmg / g and a glass transition temperature of 59 ° C, and the melt viscosity by a flow tester (Shimadzu) CFT-500 is 150,000 poise at 110 ° C.
35,400 Poise at 120 ℃, 10,700 Poise at 130 ℃, 140 ℃
It was 2,150 poise. (However, temperature rising rate 3 ° C / min, orifice diameter 0.5mm, orifice length 1.0mm, charge 20Kg) The saturated polyester resin was crushed into 2mm path, and 88 parts of the crushed product, bis manufactured by Mitsubishi Gas Chemical Co., Inc. A composition comprising 2 parts of maleimide / triazine resin (BT-2170), 2 parts of polypropylene wax (Viscole 550-P manufactured by Sanyo Kasei Co., Ltd.) and 78 parts of carbon black (Mitsubishi # 44 of Mitsubishi Kasei Co., Ltd.) The mixture was premixed and then melt-mixed by a twin-screw kneader adjusted to 140 ° C. under a condition of a residence time of about 1 minute. The obtained mixture was cooled, coarsely pulverized to 2 mm or less with a hammer mill, and further finely pulverized with a jet mill equipped with a classifier. The resulting toner had an average particle size of 7.85μ.

95 parts of iron powder was added to 5 parts of this toner and stirred with a ball mill to obtain a developer.

The charge amount of the developer is -35.6 μc / g (stirring 3 minutes), -31.0
μc / g (stirring 10 minutes), −31.5 μc / g stirring 30 minutes).
(Blow-off powder charge measuring device; Toshiba Chemical Co., Ltd.)
MODEL TB-200 manufactured by Mita Kogyo Co., Ltd.
DC-232) and set the fixing roll temperature from 120 ℃ to 20 ℃.
A copy test was conducted by changing the temperature to 0 ° C.

Fixing is good from 145 ℃, clear image is obtained, and 200 ℃
However, the offset phenomenon did not occur at all. Further, the fixing roll temperature was set to 170 ° C. and continuous copying of 10,000 sheets was performed, but no stain on the back surface was observed.

Control Example 1 The same procedure as in Example 1 was performed except that the use of BT-2170 was omitted.

Offset occurred at 160 ° C, and stains were found on the back side of about 1,000 sheets in continuous copying at 150 ° C.

Examples 2 to 4 Experiments were conducted according to Example 1 under the conditions shown in Table 1. The results are shown below.

Control Examples 2 to 5 Experiments were performed according to Example 1 under conditions other than those specified in the present application.
The results are shown in Table 2.

[Effect] The toner binder of the present invention has a low-temperature fixing property and does not cause an offset phenomenon at all, and thus is of high practical value.

Claims (1)

[Claims] 1. A glass transition temperature of 30 to 70 ° C., an acid value of 10 KOHmg / g
A binder for toner comprising 100 parts by weight of the above saturated polyester resin and 1 to 20 parts by weight of a maleimide prepolymer.