JPH0798515A - Resin composition for toner and toner - Google Patents

Abstract

PURPOSE:To obtain a toner excellent in low-temp. fixability, anti-offsetting property and blocking resistance by using a thermotropic liq. crystal polymer having a side chain as an essential component. CONSTITUTION:This liq. crystal polymer does not exhibit flowability at all at a temp. below the glass transition temp. (Tg) of the principal chain because of a glassy state but exhibits flowability at a temp. above the temp. Tg because the molecular motion of the side chain is enabled. When the polymer is heated to a temp. above the temp. (Ti) at which a liq. crystalline state turns into an isotropic state, it becomes a completely molten state and fixes at a lower temp. Since the melt viscosity of the polymer in a liq. crystalline state is higher than that in an isotropic state, satisfactory anti-offsetting property is ensured. The temps. Tg, Ti can be arbitrarily set by properly determining the molecular structure of the principal chain and the molecular structures of flexible and rigid parts in the side chain and a bonding resin excellent in blocking resistance and anti-offsetting property can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for toner used in electrophotography and the like.
The present invention relates to a resin composition for a heat fixing type developing toner used in a so-called dry developing method of developing an electrostatic image and a toner.

[0002]

2. Description of the Related Art In a dry developing method, a toner is usually charged by friction with iron or glass beads called a carrier, which is attached to an electrostatic latent image on a photoreceptor by an electric attraction, and then on a paper. And is fixed by a heating roll or the like to form a permanent visible image. As a fixing method, a heating roll method is often used in which a toner image on a sheet to be fixed is passed while being in pressure contact with the surface of a heating roll whose surface is formed of a material having releasability for toner. ing. In this heating roll method, a resin that can be fixed at a lower temperature has been required in order to reduce power consumption, improve economy, and increase copying speed.

On the other hand, when the temperature of the heating roll rises, a phenomenon (hot offset) in which toner is fused to the heating roll appears. The temperature at which this hot offset occurs is desired to be high, and it is also necessary to have blocking resistance at a temperature of 60 ° C. or lower. In order to satisfy these three characteristics of low-temperature fixability, offset resistance, and blocking resistance, a binder resin for toner has conventionally been a styrene-acrylic resin composed of a low molecular weight polymer component and a high molecular weight polymer component. (Japanese Patent Laid-Open No. 56-158340)
However, a sufficiently low fixing temperature could not be obtained.

[0004]

The conventional binder resin for toner is in a state called a glass region below the glass transition temperature (Tg) and has no fluidity. Glass transition temperature (T
If it exceeds g), the binder resin will be in a state called a rubber-like region, and at the temperature of this region, polymer particles will come to coalesce (block). When the temperature further rises to reach the softening point, the binder resin melts and becomes a fluid state. In order to fix the binder resin at a lower temperature, it is desirable that the flow starting temperature of the binder resin is low and the melt viscosity is low. However, if the melt viscosity becomes too low at a high temperature, the offset resistance of the obtained toner will deteriorate.

In the heating roll fixing method, in order to perform high-speed fixing with low power consumption, it is effective to lower the softening point of the binder resin of the toner and lower the melt viscosity. When the softening point is lowered in the polymer (binder resin), the fluidity is excessively lowered, that is, the melt viscosity is significantly lowered, the offset resistance is lowered, and further, the glass transition temperature (Tg) is also lowered. Blocking resistance is also reduced. That is, when the toner using the ordinary binder resin is fixed at a low temperature, the glass transition temperature (Tg) and the melt viscosity of the binder resin decrease,
It was very difficult to balance the blocking resistance and the offset resistance of the toner.

An object of the present invention is to provide a resin composition for toner which is excellent in low-temperature fixability, offset resistance and blocking resistance, which were very difficult to balance with conventional resin compositions for toner. To provide goods and toner.

[0007]

The resin composition for a toner according to the present invention contains a side chain type thermotropic liquid crystal polymer as a main component.

In the above side chain type thermotropic liquid crystal polymer, the side chain is composed of a flexible portion and a rigid portion, and since it is possible to make a molecular motion independently of the main chain, It can behave like a liquid crystal molecule. That is, since the side chain type thermotropic liquid crystal polymer is in a glass state at a temperature equal to or lower than the glass transition temperature (Tg) of the main chain, it shows no fluidity at all, and at a temperature above the glass transition temperature (Tg). The molecular movement of the side chain becomes possible, and the side chain type thermotropic liquid crystal polymer becomes fluid. When the temperature is further raised to a temperature equal to or higher than the temperature (Ti) at which the liquid crystal state changes to the isotropic state, the side chain type thermotropic liquid crystal polymer is completely melted. Therefore, the binder resin using the side chain type thermotropic liquid crystal polymer exhibits fluidity even at a temperature lower than the softening point, unlike the conventional binder resins, so that it is fixed at a lower temperature.

The above liquid crystal state generally has three kinds of molecular orientation states of a nematic state, a smectic state and a cholesteric state. Among them, in the nematic state, the degree of molecular orientation is low and the binder resin has a low viscosity. It is suitable for low temperature fixing because it can flow.

The above side chain type thermotropic liquid crystal polymer has a high melt viscosity in the liquid crystal state as compared with that in the isotropic state, and therefore has good offset resistance. In addition, the side chain type thermotropic liquid crystal polymer has a glass transition temperature (Tg) and a glass transition temperature (Tg) which are controlled by appropriately setting the molecular structure of the main chain, the molecular structure of the flexible part and the molecular structure of the rigid part of the side chain. Since the temperature (Ti) at which the liquid crystal state changes to the isotropic state can be arbitrarily set, it is possible to obtain a binder resin having excellent blocking resistance and offset resistance.

The side chain type thermotropic liquid crystal polymer preferably has a glass transition temperature (Tg) of about 50 ° C. or more, which is a measure of offset resistance, and isotropic from the liquid crystal state in consideration of fluidity. It is preferable that the temperature (Ti) at which the state changes to about 130 ° C. or less. Many side-chain liquid crystal polymers are currently synthesized, but considering the ease of synthesis and availability of materials, etc., the main chain is a vinyl compound copolymer such as acrylic, and the side chains are flexible. Those composed of a rigid portion containing a methylene chain and a benzene ring are preferred.

In the resin composition for a toner according to the first aspect of the present invention, only the side chain type thermotropic liquid crystal polymer may be used as a binder resin to prepare a toner, or a binder used in a conventional toner. A resin may be used in combination to form a toner. Examples of the binder resin used in combination include homopolymers and copolymers of vinyl monomers such as styrenes, vinyl esters, methylene aliphatic carboxylic acid esters, vinyl ketones, and N-vinyl compounds; various polyester resins. And so on. Further, various waxes such as carnauba wax, montan wax and paraffin wax may be used in combination.

When the conventionally used binder resin is used in combination, it is preferable that the side chain type thermotropic liquid crystal polymer is contained in an amount of 50% by weight or more. Further, it is preferable that the ratio of each resin component is adjusted so that liquid crystallinity is exhibited as the whole resin.

In the resin composition for a toner according to the first aspect of the present invention, polyethylene wax, polypropylene wax or the like may be used as a release agent in addition to the side chain type thermotropic liquid crystal polymer and other binder resin. Good.

The toner according to claim 2 is the toner according to claim 1.
The toner resin composition described above is contained as a binder resin.
In the toner, various pigments other than ordinary carbon black are used as a colorant, and a magnetic substance may be added.

[0016]

The side chain type thermotropic liquid crystal polymer used as the main component in the resin composition for toner according to the first aspect of the present invention has a side chain composed of a flexible portion and a rigid portion as described above. However, the molecular chain can move independently of the main chain, and the side chain can behave similarly to a low molecular weight liquid crystal molecule. Therefore, below the glass transition temperature (Tg) of the main chain, the side chain type thermotropic liquid crystal polymer is in a glass state and exhibits no fluidity at all.

The side chain type thermotropic liquid crystal polymer is
When the glass transition temperature (Tg) is exceeded, molecular movement of the side chain becomes possible, so that a liquid crystal state can be obtained and a flowable state can be obtained. When the temperature is further raised to a temperature equal to or higher than the temperature (Ti) at which the liquid crystal state changes to the isotropic state, the side chain type thermotropic liquid crystal polymer is in a completely melted state. Therefore, unlike the conventional resins, the side chain type thermotropic liquid crystal polymer exhibits fluidity even at a temperature equal to or lower than the softening point. Therefore, the side chain type thermotropic liquid crystal polymer is a main component of the resin for toner according to claim 1. The toner according to claim 2 containing the composition fixes at a low temperature.

Further, since the side chain type thermotropic liquid crystal polymer has a relatively high melt viscosity in a liquid crystal state, a problem regarding offset resistance does not occur in the obtained toner. Further, in the side chain type thermotropic liquid crystal polymer, the glass transition temperature (Tg) and the temperature (Ti) at which the liquid crystal state changes from the isotropic state are the molecular structure of the main chain and the flexible and rigid portions of the side chain. It is set to an arbitrary value by appropriately setting the molecular structure of. Therefore, the toner according to claim 2 containing the resin composition for a toner according to claim 1 containing such a side chain type thermotropic liquid crystal polymer as a main component is also excellent in blocking resistance and offset resistance. .

[0019]

【Example】

Example 1 (1) Synthesis of Side-Chain Thermotropic Liquid Crystal Polymer A flask equipped with a stirrer and a reflux apparatus was charged with 100 g of para-nitrophenylacetic acid, 73.2 g of para-hydroxybenzyl aldehyde and 25 ml of piperidine,
The reaction product obtained by reacting with ethanol for 2 hours was purified by gel chromatography using dichloromethane as a solvent to obtain compound A.

200 g of the compound A thus obtained and 600 g of potassium carbonate were dissolved in 3,000 ml of acetone, and 1,052 g of dibromohexane was added to the resulting solution and refluxed overnight for reaction. After completion of the reaction, the solvent was evaporated and the reaction product was purified with an ethanol solution to obtain a compound B.

Polyhydroxystyrene (molecular weight: 20
92 g) was dissolved in 1,000 ml of dimethylformamide, 400 g of the compound B obtained above and 800 g of Patashonium carbonate were added, and the mixture was refluxed at 140 ° C. overnight for reaction. The obtained reaction product was precipitated in methanol to obtain a side chain type thermotropic liquid crystal polymer represented by the following structural formula (1).

The thermal properties of the side chain type thermotropic liquid crystal polymer thus obtained were measured by a differential scanning calorimeter (DSC). The glass transition temperature (Tg) was 65 ° C. and the liquid crystal state changed to an isotropic state. The transition temperature (Ti) was 119 ° C. The liquid crystal state was confirmed with a polarization microscope.

[0023]

[Chemical 1]

(2) Preparation of toner and developer 100 parts by weight of the obtained side chain type thermotropic liquid crystal polymer, carbon black ("MA-10" manufactured by Mitsubishi Kasei Co., Ltd.)
0 ") and 5 parts by weight of polypropylene wax (3 parts by weight of" Viscole 660P "manufactured by Sanyo Kasei Co., Ltd.) are melt-blended, cooled, coarsely pulverized, and further finely pulverized by a jet mill.
A toner powder having an average particle size of about 12 to 15 microns was obtained. Toner was prepared by adding 0.3 parts by weight of hydrophobic silica powder (“R-972” manufactured by Nippon Aerosil Co., Ltd.) to the obtained toner powder. Further, 4 parts by weight of the obtained toner was mixed with 96 parts by weight of an iron carrier having an average particle size of about 50 to 800 microns to prepare a developer.

(3) Evaluation of toner and developer The toner obtained above was allowed to stand in a constant temperature bath at 60 ° C. for 16 hours, and then a powder tester (manufactured by Hosokawa Micron Corporation).
When the degree of cohesion is measured with, cohesiveness (blocking property)
Was not recognized. Next, using the developer obtained above, a copy was obtained by an electrophotographic copying machine modified from "DC-5055" manufactured by Mita Kogyo Co., Ltd. The developer is 110 ℃
At such a low fixing temperature, a sufficient degree of fixing was exhibited, and the offset generation temperature was 160 ° C. or higher, which was sufficiently high.

Example 2 (1) Synthesis of Side-Chain Thermotropic Liquid Crystal Polymer A flask equipped with a stirrer, a reflux condenser and a dropping funnel was charged with 1 mol of 4-hydroxybenzoic acid and 150 potassium hydroxide.
g, ethanol 350 ml and water 150 ml,
The mixture was refluxed for 2 hours and stirred. Next, 1.1 mol of 2-chloroethanol was added dropwise and refluxed for 15 hours, followed by stirring to react. The solvent was removed from the obtained reaction product, the solid content was dissolved in water, washed with ether, reprecipitated with hydrochloric acid, and recrystallized with ethanol to obtain a compound C.

Dea was added with 0.25 mol of the obtained compound C, 0.25 mol of allylic acid, 150 ml of chloroform, 10 g of paratoluenesulfonic acid and 10 g of hydroquinone.
It was fed to the n-Stark apparatus and refluxed to react until 4.5 ml of water was obtained. The resulting reaction solution was cooled, diluted with excess ether, washed with warm water, dried over sodium sulfate, the solvent was removed, and the residue was recrystallized with isopropyl alcohol to obtain a compound D.

0.3 mol of the obtained compound D, 2.1 g of dimethylformamide (DMF), 0.5 g of 2,6-di-t-butyl-4-methylphenol and 200 ml of thionyl chloride were fed to a flask equipped with a stirrer. , 30 ° C
After reacting with stirring for 30 minutes at room temperature, thionyl chloride was removed under reduced pressure, and the obtained reaction product was treated with 500 m of ether.
It was dissolved in 1. To this solution, 0.3 mol of 4-methoxyphenol, 5 ml of triethylamine and 200 ml of tetrahydrofuran (THF) were added, and the mixture was stirred at 0 ° C for 15 minutes to cause a reaction. The solvent was removed from the obtained reaction solution, the solid content was dissolved in chloroform, washed with water, and then dried over sodium sulfate to obtain compound E.

10 g of the obtained compound E, 100 ml of tetrahydrofuran (THF) and 0.1 g of 2,2'-azobisisobutyronitrile (AIBN) were fed to a flask equipped with a stirrer and stirred at 55 ° C. for 8 hours to react. Then, a side chain type thermotropic liquid crystal polymer represented by the following structural formula (2) was obtained.

The side chain type thermotropic liquid crystal polymer thus obtained had a weight average molecular weight of 55,000, and its thermal property was measured by a differential scanning calorimeter (DSC). The glass transition temperature (Tg) Was 62 ° C., and the temperature (Ti) at which the liquid crystal state changed to the isotropic state was 116 ° C.
The liquid crystal state was confirmed with a polarization microscope.

[0031]

[Chemical 2]

(2) Preparation of Toner and Developer A toner and developer were prepared in the same manner as in Example 1 except that the obtained side chain type thermotropic liquid crystal polymer was used.

(3) Evaluation of Toner and Developer When the degree of aggregation was measured in the same manner as in Example 1 except that the toner obtained above was used, no aggregation (blocking) was observed. Next, using the developer obtained above, a copy was obtained by an electrophotographic copying machine modified from Fuji Xerox "Able 1300". The developer is
A sufficient fixing degree was exhibited at a fixing temperature as low as 110 ° C., and an offset generation temperature was 160 ° C. or higher, which was sufficiently high.

Example 3 The weight average molecular weight was 68,000, the glass transition temperature (Tg) was 59 ° C. and the liquid crystal state was the same as in Example 1 except that 4-cyanophenol was used in place of 4-methoxyphenol. The temperature (Ti) at which the side chains change to 130 ° C. is 130 ° C., the side chain type thermotropic liquid crystal polymer represented by the following structural formula (3) is obtained, and the side chain type thermotropic liquid crystal polymer thus obtained is used. A toner and a developer were prepared and evaluated in the same manner as in Example 1.

[0035]

[Chemical 3]

Example 4 The weight average molecular weight was 95,000, the glass transition temperature (Tg) was 51 ° C. and the liquid crystal state was the same as in Example 1 except that 6-chlorohexanol was used instead of 2-chloroethanol. The temperature (Ti) at which the side chain is changed to 100 ° C. is 100 ° C., the side chain type thermotropic liquid crystal polymer represented by the following structural formula (4) is obtained, and the side chain type thermotropic liquid crystal polymer thus obtained is used. A toner and a developer were prepared and evaluated in the same manner as in Example 1.

[0037]

[Chemical 4]

Example 5 90 parts by weight of the side chain type thermotropic liquid crystal polymer obtained in Example 4 and a styrene-butyl acrylate copolymer having a weight average molecular weight of 300,000 and a glass transition temperature (Tg) of 59 ° C. (80: 20) In the same manner as in Example 1 except that a resin having a glass transition temperature (Tg) of 53 ° C. and a temperature of changing the liquid crystal state to an isotropic state (Ti) of 110 ° C. obtained by blending with 10 was used. Toners and developers were prepared and evaluated.

Comparative Example 1 A styrene / n-butyl acrylate / 2-ethylhexyl acrylate copolymer (weight average molecular weight 74,000, weight average molecular weight / number average molecular weight: 19.0) was used instead of the side chain type thermotropic liquid crystal polymer. A toner and a developer were prepared and evaluated in the same manner as in Example 1 except that the glass transition temperature (Tg) was 60 ° C. and the softening temperature was 118 ° C.

The results of Examples 1 to 5 and Comparative Example 1 are shown in Table 1.

[0041]

[Table 1]

[0042]

The resin composition for a toner according to the present invention comprises a side chain type thermotropic liquid crystal polymer as a main component, and the side chain type thermotropic liquid crystal polymer is in a glass state, a liquid crystal state and a molten state. By exhibiting these three different states, a toner having excellent offset resistance and blocking resistance and fixing at a lower temperature can be obtained. Further, since the toner of the invention described in claim 2 contains the resin composition for a toner described in claim 1, the toner has excellent offset resistance and blocking resistance, and is fixed at a lower temperature.

Claims (2)

[Claims] 1. A resin composition for a toner, which comprises a side chain type thermotropic liquid crystal polymer as a main component. 2. A toner comprising the toner resin composition according to claim 1 as a binder resin.