JPH0980815A - Resin for toner, its production and toner for developing electrostatic charge image using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin capable of giving a toner excellent in low-temp. fixability, having satisfactory fixability excellent in anti-offsetting and excellent also in developing characteristics and to obtain a toner using the resin. SOLUTION: This resin is polyester-based resin obtd. by a reaction with a monoepoxy compd. represented by the formula. When the polyester-based resin is synthesized by a melt polycondensation method, a process for allowing the monoepoxy compd. to react at 140-160 deg.C reaction temp. is included. In the formula, each of R1 and R2 is H, an alkyl, alkyloxy or acyloxy, both of them are not H and the aliphatic part of each of the alkyl, alkyloxy and acyloxy has >=8C atoms.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for electrostatic charge development used in electrophotography, electrostatic recording, electrostatic printing, etc., a toner resin used therein, and a method for producing the toner resin.

[0002]

2. Description of the Related Art In electrophotography, electrostatic recording, electrostatic printing, etc., an electrostatic charge image formed on an electrostatic charge image support is visualized by toner particles containing a resin and a colorant as main components. It The visualized image is fixed on the electrostatic image support as it is, or transferred to another support and then fixed. Therefore, the toner is required to have not only developability but also good transferability and fixability. In recent years, there is a strong demand for toners that can be fixed with low energy from the viewpoint of energy saving. The heat fixing method is roughly classified into a non-contact heating method such as oven fixing and a contact heating method such as heat roller fixing. The contact heat fixing method has high thermal efficiency,
There are advantages that the fixing unit does not use large electric power and that the fixing unit can be downsized. Therefore, it is a preferable method from the viewpoint of energy saving. However, this method has a problem that an offset occurs. The offset is a phenomenon in which a part of the toner forming an image is transferred to the surface of the heating roller during fixing, and this is transferred onto the next support to be fed to contaminate the image. Various proposals have been made to prevent this offset phenomenon.

One of them is a proposal to add a compound having releasability such as wax to the toner. This proposal has been widely implemented. However, when this compound is blended, the wax adheres to the photoreceptor, so-called filming is likely to occur, and the storage stability of the toner is poor. There is also a proposal to use a high molecular weight polymer as a resin forming the toner. In this case, offset can be prevented, but there are problems that the softening point becomes high and the fixing temperature becomes high, and that the resin is tough, so that it becomes difficult to pulverize during the toner production, and it is not practical. As a solution to this problem, a toner using a vinyl-based polymer such as styrene having a wide molecular weight distribution from low molecular weight to high molecular weight as a resin has been proposed. This toner is somewhat satisfactory in terms of offset prevention and fixability,
The fixability at low temperatures is not satisfactory. On the other hand, in the case of a condensation resin represented by a polyester resin, a polymer having a relatively low molecular weight can be obtained. Therefore, a toner capable of low-temperature fixing using this has been proposed. This toner has a problem that offset occurs at a high fixing temperature. Further, a toner obtained by mixing and blending a high molecular weight vinyl polymer and a low molecular weight polyester resin is disclosed in JP-A-54-114245, JP-A-58-11955 and JP-A-58-14147. Proposed. Although this toner has some effect in preventing offset when the temperature of the fixing roller rises above a predetermined fixing temperature, it is difficult to uniformly mix both resins, and thus triboelectric charging tends to be non-uniform. The problem remains.

Further, a toner using a resin having a crosslinked structure using an alcohol having a valence of 3 or more and / or a carboxylic acid having a valence of 3 or more as one monomer component of a polyester resin is disclosed in JP-A-54-86342. 56-195
2, JP-A-56-21136, JP-A-56-16866
0, JP-A-57-37353, and JP-A-58-1414.
6, JP-A-59-30542, JP-A-61-10556
1, JP-A-61-1105563, JP-A-61-1249
61, Japanese Patent Laid-Open No. 61-275769. However, even in toners using these resins, when the amount of the polyhydric alcohol or polycarboxylic acid blended in the resin is 30 mol% or less, the crosslinking reaction does not proceed sufficiently and the offset prevention effect is insufficient. Is. Further, when the content is more than 30 mol%, the offset preventing effect is recognized. However, there is a problem in that unreacted alcoholic hydroxyl groups and carbonyl groups of carboxylic acids are likely to remain, and the moisture resistance of the toner is significantly reduced. In addition, since the crosslinking reaction proceeds and the melting start temperature of the resin rises, the minimum fixing temperature of the toner also rises, which is not useful for low temperature fixing.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the above-mentioned conventional toners and to have good fixability that is excellent in low-temperature fixability and offset prevention.
Another object of the present invention is to provide an electrostatic charge developing toner having excellent developing characteristics and a toner resin capable of obtaining the electrostatic charge developing toner.

[0006]

SUMMARY OF THE INVENTION The present invention is a polyester-based toner resin, which is obtained by reacting a monoepoxy compound having the following structure. Further, it is a toner for electrostatic charge development using the toner resin. Also, in the process of synthesizing the polyester resin by the melt polycondensation method,
A method for producing a toner resin, comprising a step of reacting a monoepoxy compound having the following structure at a reaction temperature of 140 ° C to 160 ° C.

Embedded image (In the formula, R ₁ and R ₂ are hydrogen, an alkyl group, an alkyloxy group or an acyloxy group, and they may be the same or different, but those in which both are hydrogen are excluded. The carbon number of the aliphatic portion of the base group and the acyloxy group is 8 or more.) In the polyester-based toner resin to which the monoepoxy compound having the above structure is reacted, the aliphatic portion of the monoepoxy compound is grafted to the polyester resin. Become a structure. Then, the grafted aliphatic portion exerts a releasing effect like wax, and when the toner is fixed at a low temperature, it has an effect of preventing the occurrence of offset. The polyester-based toner resin of the present invention is produced by a melt polycondensation method, and the melt polycondensation method is one of reaction methods for synthesizing a polymer, and is particularly widely used as an industrial production method for polyesters and polyamides. Has been adopted. This is a polycondensation reaction carried out in the molten state, and is applied only to stable monomers and polymers that do not decompose during melting. This reaction is usually 180 ℃
It is carried out at a temperature of ~ 300 ° C. Particularly in the case of a combination of monomers having poor reactivity, it is carried out at a relatively high temperature side within the above range. In order to react the monoepoxy compound having the above structure with the polyester resin by the melt polycondensation method, the monoepoxy compound is used as one component of the monomer, and the epoxy ring of the monoepoxy compound is opened using a catalyst. A process is required. This is 140 in the melt polycondensation method.
It is achieved by including a step at a reaction temperature of ℃ to 160 ℃. As described above, in the usual melt polycondensation method, the reaction temperature is 180 ° C. or higher, and the reaction is not performed at a temperature of 140 ° C. to 160 ° C. At a reaction temperature of less than 140 ° C., not only the ring opening of the epoxy ring does not occur, but also the polyester resin forming reaction due to the condensation of other monomer components does not occur. Further, including the step of less than 140 ° C. only prolongs the reaction process, which is disadvantageous for resin production. On the other hand, when the melt polycondensation method is performed only at a temperature higher than 160 ° C. without including the step in which the reaction temperature is 140 ° C. to 160 ° C., the condensation reaction occurs only with the monomer other than the monoepoxy compound, and the resin is formed. . Therefore, the unreacted monoepoxy compound remains in this resin, and the physical properties of the resin such as a decrease in glass transition point are inferior, and problems such as low-temperature fixability occur when used as a toner. The catalyst is preferably a quaternary ammonium salt such as tetraethylammonium bromide, tetramethylammonium iodide or tetramethylammonium chloride, and the amount of the catalyst used is 0.1 to 1% by weight based on the monoepoxy compound. It is preferable.

The polyester-based toner resin of the present invention is
A composition containing the monoepoxy compound, a diol component, a dicarboxylic acid or an anhydride thereof or a lower alkyl ester thereof, and a polyol, a polycarboxylic acid or an anhydride thereof or a lower alkyl ester as a main component was polycondensed. It is preferably a polyester resin. Examples of the diol component include the following compounds. Polyethylene glycol, polypropylene glycol, diethanolamine, ethylene glycol, diethylene glycol, propylene glycol, isoprene glycol, octane diol, 2,2-diethyl-1,
3-propanediol, spiroglycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,6-hexanediol, hexylene Glycol, 1,5-pentanediol, 3-methyl-
1,5-Pentanediol, hydrobenzoin, bis (β-hydroxyethyl) terephthalate, bis (hydroxybutyl) terephthalate, polyoxyethylenated bisphenol A, polyoxypropyleneated bisphenol A, polyoxyethylenated biphenol, polyoxypropyleneated Biphenol etc. Moreover, the following compounds are illustrated as dicarboxylic acid or its lower alkyl ester. Fumaric acid, maleic acid, succinic acid, itaconic acid, mesaconic acid, citraconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, cyclohexenedicarboxylic acid, adipic acid, sebacic acid, dodecanedioic acid, naphthalenedicarboxylic acid Acid, biphenyl-4,4-dicarboxylic acid, 2,3-piperazine-dicarboxylic acid, iminodicarboxylic acid, imidazole-4,5-dicarboxylic acid, piperidinedicarboxylic acid, N-phenylpyrazoledicarboxylic acid, pyridinedicarboxylic acid, carbazole- 3,6-dicarboxylic acid, 9
-Methylcarbazole-3,6-dicarboxylic acid, carbazole-3,6-dibutyric acid, carbazole-3,6-γ,
γ′-Diketobutyric acid or the like can be used. Aliphatic components such as alkyl or alkenyl dicarboxylic acids having 6 or more carbon atoms such as dodecane dicarboxylic acid are particularly useful. Examples of the polyol include glycerin, trimethylolpropane, trimethylolethane, triethanolamine, pentaerythritol, sorbitol, glycerol, 1,3,5-trihydroxymethylbenzene and the like. Moreover, the following compounds are illustrated as a polycarboxylic acid. Trimellitic acid, pyromellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 2,5
7-naphthalenedicarboxylic acid, pyridinetricarboxylic acid, pyridine-2,3,4,6-tetracarboxylic acid,
1,2,7,8-tetracarboxylic acid, their acid anhydrides, their lower alkyl esters, etc. can be used. The mixing ratio of the diol component, the dicarboxylic acid or its anhydride or its lower alkyl ester, the polyol, and the polycarboxylic acid in the polyester resin can be arbitrarily changed.

The toner resin of the present invention has a glass transition point of 50 ° C. or higher as measured by a differential scanning calorimeter (DSC), a melting start temperature of 70 ° C. or higher and a flow softening point of 150 ° C. or lower as measured by a flow tester. Is desirable. In this case, if the glass transition point is lower than 50 ° C. or the melting start temperature is lower than 70 ° C., the storage stability of the toner is lowered, which is not preferable, and if the flow softening point is higher than 150 ° C., it becomes difficult to fix at a low temperature. . The melting start temperature and the flow softening point were measured using an elevated flow tester CFT-500C manufactured by Shimadzu Corporation as follows. That is, the resin pellets are put into a cylinder having an area of approximately 1 cm ² preheated to 50 to 80 ° C. A nozzle having a diameter of 1 mm and a length of 1 mm is provided at the bottom of this cylinder. Area 1 with a load of 20 KgF
Place a cm ² plunger on top of the resin pellet. Heating rate of resin pellets in the cylinder is 6 ° C / mi
The resin softened by heating at n is discharged from the nozzle. The start of the descent of the plunger was defined as the melting start temperature, and the temperature at the time when the plunger reached half the distance from the start of the descent of the plunger to the bottom of the cylinder was defined as the flow softening point.

The electrostatic charge developing toner of the present invention has the above-mentioned toner resin and colorant as essential constituents, and in addition, has improved characteristics of other resins, magnetic materials, release agents, charge control agents, fluidizing agents and the like. It is also possible to mix an agent. The colorant, carbon black, nigrosine dye, aniline blue, chalco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose. Mention may be made of Bengal, mixtures of these and the like. It is necessary that these colorants are contained in a sufficient concentration to form a visible image with a sufficient density, and usually about 1 to 20 parts by weight based on 100 parts by weight of the binder resin. As a magnetic substance, a metal or alloy showing ferromagnetism such as ferrite, magnetite, and other iron, cobalt, nickel, etc., or a compound containing these elements, or containing no ferromagnetic element, it is strengthened by applying an appropriate heat treatment. There may be mentioned compounds which become magnetic, for example manganese-copper-aluminum, manganese-copper-tin and other alloys of the type called Heusler alloys containing manganese and copper, or chromium dioxide. These magnetic materials are uniformly dispersed in the binder resin in the form of fine powder having an average particle size of 0.1 to 1 μm. The content thereof in the toner is 20 to 70% by weight, preferably 40 to 70% by weight. The charge control agent includes positive charge and negative charge. Examples of positive charging include nigrosine dyes, ammonium salts, pyridinium salts, azines and the like. For negative charging, a chromium complex, an iron complex, etc. are exemplified. These charge control agents are usually added in an amount of 0.1 to 10% by weight based on the binder resin. The toner for electrostatic charge development of the present invention is mixed with a carrier made of ferrite powder, iron powder or the like to form a two-component developer. When a magnetic material is contained, it may be used as it is as a one-component developer for developing an electrostatic image without mixing with a carrier, or it may be mixed with a carrier and used as a two-component developer. Further, it can be applied to a non-magnetic one-component developing method.

[0010]

The present invention will be described in more detail with reference to synthetic examples and examples, but the present invention is not limited thereto. <Example 1> (1-a) Synthesis of resin for toner Polyoxyethylenated bisphenol A 85.3 g
(0.27 mol) and isophthalic acid 49.8 g (0.3 mol), pentaerythritol 2.04 g (0.015 mol), a monoepoxy compound having a long-chain alkyl group (R
₂ = hydrogen, R ₁ = equal amount mixture of C ₁₂ and C ₁₄ , 5.88 g of trade name: AOEX24, manufactured by Daicel Chemical Co., Ltd., and 0.3 g of dibutyltin oxide as a catalyst and 0.03 g of tetramethylammonium chloride are stirred, Place in a 4-neck round bottom flask equipped with a condenser and nitrogen inlet,
The mixture was heated and stirred at 150 ° C. for 1.5 hours while introducing nitrogen gas from the nitrogen gas introduction pipe. 2 hours at 180 ℃ for 2 hours
The toner resin of the present invention was obtained by heating and stirring at 00 ° C. for 2 hours and 220 ° C. for 2 hours. The glass transition point of this toner resin is 64 ° C., the melting start temperature is 95 ° C., and the flow softening point is 12
The number average molecular weight was 5400 at 3 ° C. Using a twin-screw kneader, the mixture having the above-mentioned composition is used for about 130
Melt kneading was carried out at ℃. And after cooling the molten mixture,
The particles were pulverized and classified to obtain negatively chargeable toner particles having an average particle diameter of 8.5 μm. To 100 parts by weight of the toner particles, 0.5 part by weight of hydrophobic colloidal silica was externally added to obtain an electrostatic charge developing toner of the present invention. This electrostatic charge developing toner had a glass transition point of 64 ° C., a melting start temperature of 96 ° C., and a flow softening point of 122 ° C.

<Example 2> (2-a) Synthesis of resin for toner 85.3 g of polyoxyethylenated bisphenol A
(0.27 mol), isophthalic acid 49.8 g (0.3 mol), pentaerythritol 2.04 g (0.015 mol), a monoepoxy compound having a long-chain alkyloxy group (R ₁ = hydrogen, R ₂ = Decyl ether, manufactured by NOF CORPORATION
Product name: Epiol L-41) 10 g and dibutyltin oxide 0.3 g as a catalyst and tetramethylammonium chloride 0.03 g were placed in a four-neck round bottom flask equipped with a stirrer, a condenser and a nitrogen inlet tube, and a nitrogen gas inlet tube. 1.5 at 150 ° C while introducing nitrogen gas from
The mixture was heated and stirred for an hour. Then at 180 ℃ for 2 hours, 200 ℃
The mixture was heated and stirred for 2 hours at 220 ° C. for 2 hours to obtain the toner resin of the present invention. The glass transition point of this toner resin is 62
℃, melting start temperature is 93 ℃, flow softening point is 120 ℃,
The number average molecular weight was 5,000. Using a twin-screw kneader, the mixture having the above-mentioned composition is used for about 130
Melt kneading was carried out at ℃. And after cooling the molten mixture,
The particles were pulverized and classified to obtain negatively chargeable toner particles having an average particle diameter of 8.5 μm. To 100 parts by weight of the toner particles, 0.5 part by weight of hydrophobic colloidal silica was externally added to obtain an electrostatic charge developing toner of the present invention. The electrostatic charge developing toner had a glass transition point of 63 ° C., a melting start temperature of 96 ° C., and a flow softening point of 124 ° C.

Comparative Example 1 (H1-a) Synthesis of Resin for Toner A resin was synthesized in the same manner as in Example 1, but the monoepoxy compound was not used. That is, 94.8 g (0.3 mol) of polyoxyethylenated bisphenol A, 49.8 g (0.3 mol) of isophthalic acid, 2.04 g (0.015 mol) of pentaerythritol and 0.3 g of dibutyltin oxide as a catalyst were added. Put in a four-necked round bottom flask equipped with a stirrer, a condenser and a nitrogen introducing tube, and while introducing nitrogen gas from the nitrogen gas introducing tube at 180 ° C. for 2 hours,
The resin for toner was obtained by heating and stirring at 200 ° C. for 2 hours and 220 ° C. for 2 hours. The glass transition point of this toner resin is 66.
℃, melting start temperature is 110 ℃, flow softening point is 141
C., the number average molecular weight was 6,200. Preparation of (H1-b) Toner A toner for electrostatic charge development is prepared in the same manner as in Example 1 except that the toner resin of (H1-a) is used in place of the toner resin of (1-a). did. This electrostatic charge developing toner has a glass transition point of 66 ° C. and a melting start temperature of 1
The softening point was 12 ° C and the flow softening point was 138 ° C.

Comparative Example 2 (H2-a) Synthesis of Resin for Toner A resin was synthesized in the same manner as in Example 1, except that the step of reacting at 150 ° C. was omitted. That is, 85.3 g (0.27 mol) of polyoxyethylenated bisphenol A, 49.8 g (0.3 mol) of isophthalic acid, 2.04 g (0.015 mol) of pentaerythritol, and a monoepoxy compound having a long-chain alkyl group. (R ₂ = hydrogen, R ₁ = equivalent mixture of C ₁₂ and C ₁₄ , manufactured by Daicel Chemical Industries, Ltd., trade name: AOEX2
4) 5.88 g and 0.3 g of dibutyltin oxide as a catalyst and 0.0 of tetramethylammonium chloride
3 g was placed in a 4-neck round bottom flask equipped with a stirrer, a condenser and a nitrogen introduction tube, and heated at 180 ° C. for 3 hours, 200 ° C. for 2 hours, and 220 ° C. for 2 hours while introducing nitrogen gas from the nitrogen gas introduction tube. The resin for toner was obtained by stirring.
This toner resin had a glass transition point of 57 ° C., a melting start temperature of 115 ° C., a flow softening point of 140 ° C., and a number average molecular weight of 5,400. In addition, no reaction of the monoepoxy compound was observed in this resin, and it remained as an unreacted product in the resin, lowering the glass transition point. (H2-b) Preparation of Toner An electrostatic charge development toner was prepared in the same manner as in Example 1 except that the (H2-a) toner resin was used in place of the (1-a) binder resin. did. This electrostatic charge developing toner has a glass transition point of 57 ° C. and a melting start temperature of 113.
C., the flow softening point was 132.degree.

Next, Examples 1-2 and Comparative Examples 1-2
Toner for development with electrostatic charge and ferrite carrier (trade name: FL-96-203, manufactured by Powder Tech Co., Ltd.)
0) and 5) were mixed in a weight ratio of 5:95 to prepare a two-component developer. Next, an unfixed image was picked up by a copying machine (trade name: SFT-Z133, manufactured by Sanyo Electric Co., Ltd.) using each of the above two-component developers, and then a fixing roller coated with Teflon surface and a pressure-bonded surface coated with silicone rubber. The toner image was heat-fixed on the high-quality paper using a fixing device composed of a roller. At this time, the surface temperature of the fixing roller was 130 ± 5 ° C., and the linear velocity was 200 mm / sec. Next, rub the fixed image with a cotton pad and calculate the fixing strength by the following formula,
It was used as an index of low energy fixability. The image density was measured with a Macbeth reflection densitometer RD-914.

[Equation 1] In addition, the surface temperature of the fixing roller of the copying machine (the linear velocity is 200 mm / sec) using the two-component developer and the copying machine.
The fixed image was captured while changing the stepwise, and the presence or absence of the offset phenomenon at each surface temperature was visually confirmed to evaluate the non-offset temperature region. The difference between the maximum value and the minimum value in the non-offset temperature region was defined as the non-offset temperature width. Table 1 shows the evaluation results of the fixing strength, the non-offset temperature region and the non-offset temperature width.

[0015]

[Table 1]

As is clear from the evaluation results of Table 1, the electrostatic charge developing toner of the present invention has a fixing roller surface temperature of 130.
It was confirmed that the fixing strength was 90% or more, which was a sufficient practical property, and the non-offset temperature range was within a practically acceptable range, despite the low temperature of ° C. On the other hand, in the electrostatic charge developing toners of Comparative Examples 1 and 2, 1
Fixing could not be carried out at 30 ° C., so that the fixing strength could not be measured, and the non-offset temperature width was 95 ° C. or less, which was narrower than that of the example. In addition, Examples 1-2
The two-component developer obtained in 1.
When 0 sheets were continuously copied, the Macbeth reflection density of the solid image was 1.4 or more, and the background fog in the non-image area was 0.1 or less. I was able to get it.

[0017]

INDUSTRIAL APPLICABILITY When the toner resin of the present invention is used as a toner for electrostatic charge development, it has excellent low-temperature fixability, does not cause an offset phenomenon in a wide temperature range, and can exhibit good developing characteristics. is there.

Claims (3)

[Claims] 1. A resin for polyester toner, which is obtained by reacting a monoepoxy compound having the following structure. Embedded image (In the formula, R ₁ and R ₂ are hydrogen, an alkyl group, an alkyloxy group or an acyloxy group, and they may be the same or different, but those in which both are hydrogen are excluded. The number of carbon atoms in the aliphatic portion of the base and the acyloxy group is 8 or more.) 2. A process for synthesizing a polyester resin by a melt polycondensation method, which comprises the step of reacting a monoepoxy compound having the following structure at a reaction temperature of 140 ° C. to 160 ° C. Method. Embedded image (In the formula, R ₁ and R ₂ are hydrogen, an alkyl group, an alkyloxy group or an acyloxy group, and they may be the same or different, but those in which both are hydrogen are excluded. The number of carbon atoms in the aliphatic portion of the base and the acyloxy group is 8 or more.) 3. A toner for electrostatic charge development comprising a binder resin and a colorant as main components, wherein the binder resin is a polyester resin obtained by reacting a monoepoxy compound having the following structure. Toner for charge development. Embedded image (In the formula, R ₁ and R ₂ are hydrogen, an alkyl group, an alkyloxy group or an acyloxy group, and they may be the same or different, but those in which both are hydrogen are excluded. The number of carbon atoms in the aliphatic portion of the base and the acyloxy group is 8 or more.)