JPH07140712A - Resin composition for toner and toner - Google Patents

Abstract

PURPOSE:To obtain a resin compsn. for a toner excellent in low temp. fixing property, anti-offset property, and anti-blocking property by using a main-chain thermotropic liquid crystal polymer as the main component. CONSTITUTION:A main-chain thermotropic liquid crystal polymer is used as the main component. It is preferable that this main-chain thermotropic liquid crystal polymer can have four different states of a glass state, crystal state, liquid crystal state and isotropic state (molten state). The main-chain thermotropic liquid crystal polymer consists of a flexible part and a rigid part. Since the flexible part can independently have molecular kinetics from the rigid part, the polymer can have a liquid crystal state in which the polymer is not completely molten but partly molten to show fluidity. Therefore, because the main-chain thermotropic liquid crystal polymer has fluidity in a liquid crystal state, the binder resin using the main-chain thermotropic liquid crystal polymer is fixed at rather low temp. compared to a conventional binder resin.

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 becomes high, the toner is fused to the heating roll (hot offset).
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 50 ° 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. 56-15834)
No. 0, etc.) has been proposed, but 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]

A resin composition for a toner according to the present invention comprises a main chain type thermotropic liquid crystal polymer as a main component. The above-mentioned main chain type thermotropic liquid crystal polymer is preferably one which can take four different states such as a glass state, a crystalline state, a liquid crystal state and an isotropic state (molten state). This is because if the glass state directly changes to the liquid crystal state, the preservability is low, and if the crystalline state is passed during the change from the glass state to the liquid crystal state, the preservability is improved.

The above-mentioned main-chain type thermotropic liquid crystal polymer is composed of a flexible portion and a rigid portion, and since this flexible portion can make a molecular motion independently of the rigid portion. The liquid crystal state may be such that it is not completely melted but is melted to the extent that it exhibits fluidity. Therefore, the binder resin using the main chain type thermotropic liquid crystal polymer is fixed at a lower temperature than the conventional binder resins because the main chain type thermotropic liquid crystal polymer has fluidity in the liquid crystal state.

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-mentioned main 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 main chain type thermotropic liquid crystal polymer has a glass transition temperature (Tg) by appropriately setting the molecular structure of the flexible portion, the molecular structure of the rigid portion, and the like.
Since the temperature (Tm) for changing from the crystalline state to the liquid crystal state and the temperature (Ti) for changing from the liquid crystal state to the isotropic state can be arbitrarily set, a binder resin excellent in blocking resistance, offset resistance and the like can be obtained. be able to.

The glass transition temperature (Tg), which is the temperature at which the glass state changes to the crystalline state, the temperature (Tm) that changes from the crystalline state to the liquid crystal state, and the temperature (Ti) that changes from the liquid crystal state to the isotropic state are Although it is difficult to set each independently, it is preferable that the glass transition temperature (Tg), which is a measure of anti-offset property, is about 50 ° C. or higher. Further, in consideration of fluidity, the crystalline state to the liquid crystal state The temperature (Tm) at which the liquid crystal state changes to about 60 to 80 ° C, and the temperature (Ti) at which the liquid crystal state changes to the isotropic state is 130 ° C.
It is preferably less than or equal to the degree.

Although many main chain type liquid crystal polymers have been synthesized at present, in view of easiness of synthesis, availability of materials, etc., those composed of polyester resins are preferable.

In the resin composition for a toner according to the first aspect of the present invention, only the main chain type thermotropic liquid crystal polymer may be used as a binder resin to form a toner, or a toner 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 main 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 in combination as a release agent in addition to the main chain type thermotropic liquid crystal polymer and other binder resins. 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.

[0017]

The main chain type thermotropic liquid crystal polymer used as the main component in the resin composition for toner according to the first aspect of the invention is composed of the flexible portion and the rigid portion as described above, It is possible for the solid portion to perform molecular motion independently of the rigid portion, and it may be in a liquid crystal state in which it is not completely melted but is melted to the extent that it shows fluidity. Therefore, at a temperature below the glass transition temperature (Tg), the main chain type thermotropic liquid crystal polymer is in a glass state and does not exhibit fluidity at all.

In the above-mentioned main-chain type thermotropic liquid crystal polymer, when the glass transition temperature (Tg) is exceeded, the flexible portion starts molecular motion independently of the rigid portion, and the temperature is further raised from the crystalline state to the liquid crystal state. Temperature changing to (Tm)
When the temperature reaches the above temperature, the liquid crystal state can be obtained and the liquid state can be obtained. Therefore, the main chain type thermotropic liquid crystal polymer exhibits fluidity even at a temperature equal to or lower than the softening point, unlike the conventional resins. Therefore, the main chain type thermotropic liquid crystal polymer is the main component, and the resin for toner according to claim 1. The toner according to claim 2 containing the composition fixes at a low temperature.

Further, the above-mentioned main chain type thermotropic liquid crystal polymer has a relatively high melt viscosity in a liquid crystal state, so that the toner obtained does not have a problem with respect to offset resistance. Further, in the above main chain type thermotropic liquid crystal polymer, the glass transition temperature (Tg), the temperature (Tm) at which the crystalline state changes to the liquid crystal state, and the temperature (Ti) at which the liquid crystal state changes to the isotropic state are flexible parts. It is set to an arbitrary value by appropriately setting the molecular structure of the rigid portion. Therefore, the toner according to claim 2 containing the resin composition for toner according to claim 1 containing such a main chain type thermotropic liquid crystal polymer as a main component,
Blocking resistance and offset resistance are also good. The main chain type thermotropic liquid crystal polymer has a glass state, a crystalline state, a liquid crystal state and an isotropic state (molten state).
If it can be in three different states, it will go through a crystalline state once when it changes from a glass state to a liquid crystal state, thus improving storage stability.

[0020]

【Example】

Example 1 (1) Synthesis of main-chain type thermotropic liquid crystal polymer To a flask equipped with a stirrer and a reflux condenser, 1 mol of 1,4-phthalic acid, excess thionyl chloride and a small amount of dimethylformamide as a catalyst were fed, and the mixture was stirred for 1 hour. The mixture was refluxed for reaction, unreacted thionyl chloride was removed under reduced pressure, and a solution of 0.25 mol of methylhydroquinone dissolved in a solution of 500 ml of methylene chloride and 500 ml of pyridine was slowly added dropwise at 30 ° C. for 12 hours. The reaction was carried out with stirring.

Methylene chloride 50 was added to the above reaction solution.
A solution of 0.5 ml of hexanediol and 0.25 mol of dodecanediol dissolved in a solution of 0 ml and pyridine 500 ml was slowly added dropwise at 30 ° C. to 2
The reaction was carried out for 4 hours with stirring to obtain a main chain type thermotropic liquid crystal polymer represented by the following structural formula (1).

The thermal properties of the obtained main chain type thermotropic liquid crystal polymer were measured by a differential scanning calorimeter (DSC). The glass transition temperature (Tg) was 55 ° C., and the crystal state changed to the liquid crystal state. Temperature (Tm) is 75 ° C., and the temperature (Ti) at which the liquid crystal state changes to the isotropic state is 1
It was 59 ° 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 main 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 powder carrier having an average particle size of about 50 to 80 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 50 ° C. for 16 hours, and then a powder tester (manufactured by Hosokawa Micron Corporation).
When the degree of aggregation was measured with, no aggregation (blocking) was observed. Next, using the developer obtained above,
A copy was obtained by an electrophotographic copying machine modified from "Able1300" manufactured by Fuji Xerox. The developer is 11
A sufficient fixing degree was exhibited at a fixing temperature as low as 0 ° C., and the offset generation temperature was 160 ° C. or higher, which was sufficiently high.

Example 2 Instead of 0.25 mol of methylhydroquinone and 0.25 mol of dodecanediol, methylhydroquinone of 0.
Glass transition temperature (Tg) 42 in the same manner as in Example 1 except that 15 mol and 0.35 mol of dodecanediol were used.
℃, temperature (Tm) 70 to change from crystalline state to liquid crystal state
° C and temperature (Ti) 1 at which the liquid crystal state changes to the isotropic state
Toner and development were carried out in the same manner as in Example 1 except that the main chain type thermotropic liquid crystal polymer represented by the following structural formula (2) was obtained at 29 ° C. and the obtained main chain type thermotropic liquid crystal polymer was used. An agent was prepared and evaluated.

[0027]

[Chemical 2]

Example 3 90 parts by weight of the main chain type thermotropic liquid crystal polymer obtained in Example 2 and a styrene-butyl acrylate copolymer (80: 80) having a weight average molecular weight of 300,000 and a glass transition temperature (Tg) of 59 ° C. 20) Glass transition temperature (Tg) 48 ° C., temperature at which crystalline state changes to liquid crystal state (Tm) 75 ° C., and temperature at which liquid crystal state changes to isotropic state (Ti) obtained by blending with 10 parts by weight. ) A toner and a developer were prepared and evaluated in the same manner as in Example 1 except that a resin at 140 ° C. was used.

Comparative Example 1 Instead of the main chain type thermotropic liquid crystal polymer, 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. 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 115 ° C.

The results of Examples 1 to 3 and Comparative Example 1 are shown in Table 1.

[0031]

[Table 1]

[0032]

The resin composition for a toner according to the present invention comprises a main chain type thermotropic liquid crystal polymer as a main component, and the main chain type thermotropic liquid crystal polymer is in a glass state, a crystalline liquid crystal state and the like. By exhibiting four different states, that is, a square state (fused state), a toner having excellent offset resistance and blocking resistance and fixing at a lower temperature can be obtained. Further, the toner according to the second aspect of the invention contains the resin composition for a toner according to the first aspect of the invention, and therefore 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 main 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.