JP2501938B2 - Toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] It is an object of the present invention to provide a toner used for developing an electrostatic latent image such as electrophotography, which is excellent in void resistance and fixing property and which is free from a blocking phenomenon. In a toner using a binder, as the binder, the surface tension at 200 ° C. is 30 dyne / cm or less, the melt viscosity is 100 poise or more, the storage elastic modulus is 100 dyne / cm ² or more, and the melt viscosity at 125 ° C. is 5000 poise or less. , A binder having physical properties such that the storage elastic modulus is 40,000 dyne / cm ² or less was used.

TECHNICAL FIELD The present invention relates to a toner used for developing an electrostatic latent image such as electrophotography.

As the electrophotographic method, the method described in US Pat. No. 2,297,691 is well known. This generally uses a photoconductive insulator (such as a photocondrum) to apply a uniform electrostatic charge on the photoconductive insulator by corona discharge, etc. An electrostatic latent image is formed, and this latent image is visualized by electrostatically adsorbing fine powder called toner, and after transferring the toner image to a recording medium such as paper, pressurization, heating, solvent vapor Spray of
The toner image is fixed on the recording medium by means of irradiation with light or the like to obtain a printed photograph.

[Prior Art] In electrophotography, as a toner for developing an electrostatic latent image, a colorant such as carbon black dispersed in a binder resin made of a natural or synthetic polymer substance is about 5 to 20 μm. Finely pulverized particles are used for.
Then, it is used for developing an electrostatic latent image by mixing toner alone or a carrier substance (carrier) such as iron powder or glass beads.

The developing method includes a one-component developing method and a two-component developing method.The toner used for the former usually contains magnetic powder, and this toner is rubbed against the wall surface of the developing device or the member of the developing roll. It is frictionally charged and is held on the developing roll by the magnetic force of the magnet contained in the developing roll.When the developing roll rotates, the toner is carried to the latent image portion of the photoconductive insulator, and only the charged toner is charged. Is adhered to the latent image by an electric attraction force to be developed.

In the latter two-component developing method, the developer composed of the toner and the carrier is frictionally charged by being mixed and stirred in the developing device, and the latent toner of the photoconductive insulator is held while the toner is carried on the carrier. Only the toner that is carried to the image portion and charged is selectively attached to the latent image by the electric attraction force to perform the development.

The thermal roll fixing method has been conventionally used to fix the visualized toner by developing the electrostatic latent image.However, the flash fixing using the emission energy from the xenon lamp has been noted because of the following features. ing.

Since it is non-contact fixing, the resolution of the image during development is not deteriorated.

There is no need to wait after turning on the power, and an immediate start is possible.

Even if a recording medium such as recording paper is jammed in the fixing device due to system down, it does not burn.

Glued paper, preprinted paper, paper with different thickness, etc.
Fixing is possible regardless of the material and thickness of the recording paper.

Here, the process in which the toner is fixed to the recording medium by flash fixing will be described. The toner transferred to the recording medium adheres as a powder to form an image, which is in a state of being broken by rubbing with a finger.

Next, when a flash of light is emitted using a xenon flash lamp, the toner absorbs the energy of the flash of light, so that the temperature rises and the toner softens and melts and adheres to the recording.

After the flash is over, the temperature drops and solidifies to produce a fixed image.

Here, the necessary condition of the toner is that the image is not deformed even in a melted state while being softened at a relatively low temperature.

However, not only the toner but also the solid is melted, the viscosity is lowered, and the melt is aggregated and deformed by the surface tension, and in this case, the toner image is deformed.

Conventionally, as a binder used for a toner, a low-polymer polymer generally called an oligomer has been used because of its low melting temperature and good thermal stability.

However, since these oligomers have a low melt viscosity and a low storage elastic modulus, the fixed image is likely to be deformed and the image quality is deteriorated. Also, if the light energy applied is too high, explosive fixing is likely to occur. There is a problem that a white spot phenomenon called an image void occurs and the image density is lowered.

FIG. 1 shows the occurrence of voids. The toner 1 is arranged on the recording paper 2 in a plurality of rows (a in the figure).
In addition, when the strong flash 3 (b in the same figure) is irradiated, the toner 1 is easily melted because the softening temperature of the toner 1 is low, but a void 5 is generated inside for the following reasons (c in the same figure). . In FIG. 1, reference numeral 4 denotes a fixed image.

A void 5 is formed when a part of the toner 1 reaches the decomposition temperature and a decomposed gas is generated and protrudes.

The air in the gaps between the toner particles is thermally expanded and protrudes to form voids 5.

The void 5 formed by this mechanism is the void 5 formed by explosion fixing.

Further, even when the toner 1 absorbs an appropriate energy for melting from the flash 3, if the melt viscosity and the storage elastic modulus are too low with respect to the surface tension of the toner 1, the melted toners 1 may be separated from each other. The voids 5 may be generated due to aggregation due to surface tension before solidification. In addition,
This void phenomenon is likely to occur because the fixing time is short, that is, it is necessary to irradiate a large amount of energy in a short time such as a printer or a copying machine having a high printing speed to perform fixing, and a high process speed of 700 mm / s or more. It becomes especially remarkable in the machine.

As a means for solving these problems, if the molecular weight of the binder resin is simply increased, the melting viscosity and storage elastic modulus of the toner 1 increase, but the melting point of the toner 1 also increases.
Usually, the fixing property of the toner 1 is deteriorated.

That is, in flash fixing, light energy is momentarily applied from the upper portion of the accumulated toner 1, heat due to the energy is transferred to the lower toner 1, and the lower toner 1 is melted to perform fixing ( Japanese Patent Publication 55-1408
No. 60), there is a temperature difference between the upper and lower parts of the toner, and the lower part of the toner has a relatively low temperature. For this reason, when the melting point of the toner 1 is increased, the toner 1 in the lower portion is hardly melted and the fixability is extremely lowered. This phenomenon becomes more prominent as the thickness of the toner 1 deposited by development increases,
Usually, if the thickness of the toner 1 after fixing exceeds 20 μm, good fixing property cannot be maintained. However, it is difficult to always control the thickness of the toner 1 to be developed to be constant.

Further, the flash fixing toner 1 often uses a low polymer having a softening temperature lower than that of the binder resin used for the heat roll fixing toner 1. Therefore, when exposed to a high temperature environment, the toner surface may be deteriorated. A blocking phenomenon may occur in which the toner softens and the toners associate with each other.

When the blocking phenomenon occurs, the fluidity of the toner 1 is extremely reduced, and not only the toner 1 is not smoothly supplied into the developing device, but also the particle size and the like are changed, so that the charging characteristic is changed and the good development is performed. I can't do it.

Therefore, it was also necessary to develop a toner 1 that exhibits good fixability even if the amount of the toner 1 developed to some extent fluctuates, and that neither void 5 nor blocking phenomenon occurs.

[Problems to be Solved by the Invention] As described above, in the electrophotographic toner using the flash fixing method, an epoxy resin typified by bisphenol A diglycidyl ether polymer is conventionally used as the binder. However, when such a resin is used as a binder resin, it is necessary to use an oligomer having a low softening temperature, that is, a relatively low molecular weight, in order to obtain good fixability. Such oligomers are prone to explosive fixing due to thermal decomposition, and have a problem that voids are generated due to aggregation due to high surface tension and low melt viscosity, which leads to deterioration of image quality. There is also a problem that the blocking phenomenon is likely to occur when it is carried out.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a toner that is excellent in void resistance and fixability and does not cause a blocking phenomenon.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a toner using a binder, wherein the binder has a surface tension at 200 ° C. of 30 dyne / cm or less, a melt viscosity of 100 poises or more, and a storage. The elastic modulus is 100 dyne / cm ² or more, the melt viscosity at 125 ° C. is 5000 poise or less, and the storage elastic modulus is 40,000 dyne / cm ^2.
A binder having a physical property value of not more than cm ² is used.

Further, the present invention, as the binder, a melt viscosity at 200 ° C. is 30 poise or more, a storage elastic modulus is 50 dyne / cm ² or more, and a melt viscosity at 125 ° C. is 3000 poise or less,
Binder with storage modulus of 35000 dyne / cm ² or less and 2
Melt viscosity at 00 ℃ is 120 poise or more, storage elastic modulus is 1
20dyne / cm ² or more and melt viscosity at 125 ℃ of 10,000
A binder having a poise or less and a storage elastic modulus of 100,000 dyne / cm ² or less is used as an essential component.

Further, the present invention, as the binder, a functional group capable of reacting with the first prepolymer or monomer at room temperature to exhibit rubber-like elasticity with respect to the first prepolymer or monomer forming the main chain structure of the binder by polymerization. Is used in a main chain-modified copolymer in which a monomer which is the same as the second prepolymer is introduced into the second prepolymer having 1.5 equivalents or more.

 Hereinafter, the present invention will be described in more detail.

Here, the temperature for measuring the physical properties such as surface tension and melt viscosity in the present invention is set as described above because of the following reasons.

First, considering the toner flash fixing process in a time series, the flash light irradiation process; (When the toner is irradiated with the flash light, the toner absorbs the energy of the flash light and heats up, and the surface instantaneously becomes extremely High temperature.) Heat conduction / penetration process; (The heat of the surface is conducted to the toner in the lower layer, and the entire toner softens and melts and permeates the recording medium.) Cooling / fixing process; (The temperature of the toner decreases and the toner solidifies. However, the physical behavior such as surface tension related to the occurrence of voids depends on the physical properties of the toner surface where the toner is melted at a high temperature and the physical properties of the middle-upper layer of the toner. It is based. On the other hand, the fixability is based on behaviors such as the melt viscosity of the toner until the toner cools and solidifies, the permeability of the toner into the recording medium, etc. in the toner lower layer where the toner is at a relatively low temperature. It is self-evident that the thermal, mechanical, and chemical behavior of the toner, which is deeply involved in the generation, cannot be discussed only at a single temperature such as the binder softening point. Further, the surface tension, melt viscosity, etc., which are the object of the present invention, are physical quantities having temperature dependence, and at the same time the value greatly differs depending on the measurement temperature, and at the same time, the temperature dependence is the material of the binder resin. This is because it greatly differs depending on the toner constituent material.

Conventionally, regarding the binder resin of the toner for flash fixing, JP-A-57-79957 and JP-A-63-66563 specify the melting point of the binder, and JP-A-58-215660 specifies the melt viscosity at the softening point. However, as described above, the melt viscoelasticity of the toner on the surface in contact with the recording medium is important for fixability, and the surface tension and melt viscoelasticity of the toner upper layer are important for voids. Based on the experience of the inventors, even if a toner satisfying the physical property values described in the above patent is used, an excellent flash-fixed image is not always obtained.

Therefore, in implementing the present invention, first, the temperatures of the toner upper layer portion and the toner lower layer portion were estimated based on the following experiments in each process of the above flash fixing.

(1) Estimation of Melting Temperature on Top of Toner Aggregation of toner due to surface tension, which causes void formation, occurs when the toner immediately after flash light irradiation has a relatively high temperature and a low melt viscosity and storage elastic modulus. Therefore, first, the temperature of the upper portion of the toner immediately after the flash light irradiation was estimated based on the temperature at which the binder resin is exposed and the components of the thermal decomposition fragments generated at that time.

First, the decomposition product gas of the toner generated when the toner was irradiated with flash light and melted was collected, and its components were identified by gas chromatogram-mass spectrometry (GC-MS method). Then, using a heating furnace, the toner of the same composition,
The toner was melted at a constant temperature, the decomposition product gas of the toner generated at that time was collected, and the components were identified in the same manner. The results of Table 1 were obtained when these two were compared with each other for decomposition product gas and the temperature at which decomposition product gas of the same component as flash light melting was generated in the heating furnace melting was obtained. Based on this result, it was estimated that the temperature reached by the upper portion of the toner during flash fixing was 200 ° C or higher.

(2) Estimation of Temperature of Lower Part of Toner On the other hand, regarding fixability, melt viscosity and storage elastic modulus of a lower part of toner in contact with a recording medium are important factors. Therefore, with respect to five types of flash fixing toners having different melting characteristics, the temperature reached by the temperature below the toner when the optimum fixing energy is applied to each toner was estimated by the following method. In addition,
Here, the optimum fixing energy refers to the energy at which the toner exhibits sufficient fixing strength and does not cause explosive fixing due to excess energy.

Specifically, the toner has a melting point (flow tester method) 105.
Using five types of polyester toner of ℃, 115 ℃, 125 ℃, 138 ℃, 150 ℃, the irradiation energy is changed by controlling the charging voltage of the flash light emitting capacitor, and the fixing test is performed. The optimum fixing energy in was determined. Then, a thin layer (1 to 3 μm) of a quasi-substance having a known melting point is formed on the recording medium, and a toner layer (about 10 μm) is further formed on the thin layer and irradiated with flash light to melt the toner. In addition, the temperature of the toner lower layer of each toner when the optimum fixing energy was applied was estimated depending on whether or not the pure substance sandwiched between the toner layer and the recording medium was melted. The pure substances used were phenylacetic acid (melting point 76 ° C), benzol (melting point 95 ° C), acetanilide (melting point 114.5 ° C), phenidone (melting point 121 ° C), phenacetin (melting point 135 ° C), phenanthrol (melting point 156 ° C). , Benzianilide (melting point 1
63 ° C).

 Table 2 shows the results.

From this, the temperature of the toner lower layer when the optimum fixing energy was applied was estimated to be 120 to 135 ° C.

Based on the above results, it is necessary to discuss the surface tension, melt viscoelasticity at high temperature, etc., which are the factors that cause void formation, in terms of the physical properties in the temperature range of 200 ° C or higher, and the melt viscosity, etc., that is involved in the fixability It was confirmed that the physical behavior should be discussed in the temperature range of 125 ℃. In the present invention, the temperature for discussing the physical properties during high temperature melting was set to 200 ° C. This is based on the experience of the present inventors that it is possible to estimate the quality of the fixing behavior of the toner using the physical property value of 200 ° C. as an index, and at higher temperatures, thermal decomposition and thermal polymerization of the resin become severe, This is because it becomes difficult to discuss clear physical properties.

The above experiment was carried out using a printer (D-6700D; manufactured by Fujitsu) adopting the flash fixing method in the charging voltage range of 1450V to 2550V of the light emitting capacitor.

As a result of investigations by the present inventors, the physical properties of the binder used in the toner have a surface tension at 200 ° C. of 30 dyne / cm (Wilhelmy method) or less, a melt viscosity of 100 poise or more, and a storage elastic modulus of 100 dyne / cm ² Above that, the melt viscosity at 125 ℃ is 500
Poise or less, storage elastic modulus of 40,000 dyne / cm ² or less, which makes it possible to achieve both excellent flash fixability and void resistance, but melt viscoelasticity during high temperature melting A method commonly used as a method for increasing the binder, for example, increasing the molecular weight of the binder resin.

 A crosslinked structure is introduced between the binder molecules.

When the method described above is used, the melting point of the toner and the melt viscoelasticity at low temperature melting also increase, and the fixability of the toner deteriorates. Therefore, it has been conventionally difficult to sufficiently satisfy both characteristics.

As a result of studies by the present inventors, the melt viscosity of the binder and the temperature characteristics of the storage elastic modulus are relatively high at high temperatures (specifically, 100
Poise or more / 100 dyne / cm ² or more) and low at low temperature (specifically 5000 poise or less / 40 000 dyne / cm ² or less), a binder with high melt viscosity and high storage elastic modulus at high temperature melting is used. It has been found that the above conditions can be relatively easily achieved by appropriately blending a binder having a low melt viscosity and a low storage elastic modulus when melted at a low temperature.

Specifically, as a binder having a low melt viscosity at low temperature melting and a storage elastic modulus, the melt viscosity at 200 ° C is 30 poises or more, the storage elastic modulus is 50 dyne / cm ² or more, and the melt viscosity at 125 ° C is 3000 poises or less. , Storage elastic modulus 35000dyne / cm
A binder having a melt viscosity at 200 ° C. of 120 poise or more as a binder having a melt viscosity of ² or less and a high melt viscosity at high temperature melting,
Storage modulus is 120 dyne / cm ² or more, melt viscosity at 125 ℃ is 10,000 poise or less, storage modulus is 100000 dyne / cm ²
By using the following binder is blended, the melt viscosity of the entire binder, storage elastic modulus at 125 ℃, 5000 poise or less / 40000dyne / cm ² or less, and at 200 ℃ 100 poise or more / 100dyne / cm ² It is possible to keep above.

The reason for defining the lower limits of the melt viscosity at 200 ° C. and the storage elastic modulus of Van Ida, which exhibits low melt viscosity and low storage elastic modulus at low temperature melting as 30 poise and 50 dyne / cm ² , respectively, is the experience of the present inventors. According to this, when a binder having a lower melt viscosity and a lower storage elastic modulus at this temperature is blended, even if a binder having a high melt viscosity and a high storage elastic modulus at high temperature melting is blended, the melt viscosity and the storage elasticity of the binder as a whole are This is because the ratio is often lower than a desired value, and in an extreme case, the difference in melt viscosity between both binders is large, which causes a problem such as layer separation of both binders during melting.

On the other hand, the reason why the high melt viscosity at high temperature melting, the melt viscosity at 125 ° C. of the binder exhibiting the high melt elastic modulus, and the storage elastic modulus are defined as 10,000 as 100,000 dyne / cm ² or less, respectively, is as follows.
This is because if the binder has a higher melt viscosity and a higher storage elastic modulus than this, even if the binder is blended with a binder having a low melt viscosity and a low storage elastic modulus, the penetrability into the recording medium deteriorates and fixing failure occurs.

In the binder used in the above-mentioned blend, although different in degree, low melt viscosity and low storage elastic modulus at low temperature melting and high melt viscosity and high storage elastic modulus at high temperature melting are required. According to the experience of the present inventors, it is difficult to obtain a binder exhibiting a low melt viscosity at low temperature melting, a low storage elastic modulus, and a high melt viscosity and a high storage elastic modulus. It is difficult to obtain a binder for blending which satisfies the temperature-melt viscosity and storage elastic modulus characteristics of the present invention by only partially changing the molecular structure such as the control of the above or the introduction of a crosslinked structure.

Therefore, as a method of obtaining a binder exhibiting a high melt viscosity and a high melt elastic modulus at the time of high temperature melting while preventing the increase of the melt viscoelasticity at the time of low temperature melting such as an extreme softening point increase, the present inventors have studied, It has been found that it is appropriate to use a main chain-modified copolymer obtained by modifying the main chain by introducing a component showing rubber-like elasticity into the main chain as a binder.

As a method of increasing the melt viscoelasticity during melting of the binder resin, as described above, in addition to the method of the present invention, increase the polymerization degree of the binder resin, and the main chain structure of the binder resin has a relatively long chain of C4 or more. The method of introducing a large number of side chains of, the method of introducing cross-linking between the main chain structures of the binder resin, etc. can be considered, but in general, the softening point and low temperature increase with the increase of melt viscosity and storage elastic modulus. Since the melt viscosity and the storage elastic modulus at the time of melting also increase, the occurrence of voids can be prevented, but the fixability is often impaired. The method (1) makes it possible to increase the melt viscosity during high-temperature melting without increasing the softening point, melt viscosity during low-temperature melting, and storage elastic modulus, but the degree is still insufficient. Further, in this case, the glass transition point of the binder is lowered, and the blocking resistance in a high temperature environment is often extremely impaired.

In the method of using a main chain-modified copolymer obtained by modifying the main chain by introducing a component exhibiting rubber-like elasticity into the main chain shown in the present invention, a relatively crystalline resin represented by epoxy and polyester is used. By introducing a rubber elastic component with extremely low crystallinity into the main chain structure of a good polymer, the crystallinity of the main chain structure is lowered, and as a result, a longer chain chain such as an epoxy binder commonly used for flash fixing binders is used. It is a method of obtaining a binder that has a main chain structure and maintains the softening point, the melt viscosity at low temperature melting, and the storage elastic modulus almost the same as the epoxy binder commonly used for flash fixing binders.

In addition, since such a binder has a longer chain main chain structure such as an epoxy binder commonly used for flash fixing binders, and further has a region exhibiting highly flexible rubber elasticity in the main chain structure, Since the chain structures are strongly entangled with each other, a high melt viscosity can be maintained even at a relatively high melting temperature.

As the prepolymer forming the main chain structure used in the present invention, as long as it has reactivity with a rubber elastic component, an epoxy resin, a styrene-acrylic resin, a polyester resin,
Any resin that is commonly used as a binder resin for toner, such as vinyl-based resin, can be used. However, by introducing a rubber elastic component, the hardness of the binder resin becomes slightly low, and fine pulverization after kneading the toner Therefore, it is preferable to use a resin having relatively high crystallinity and high hardness as the prepolymer forming the main chain structure.

Based on the experience of the present inventors, when the main chain is composed of a bisphenol type epoxy, the epoxy equivalent of the copolymer after the main chain modification is preferably 750 to 1000,
When the main chain is composed of polyester, the weight average molecular weight of the molecule after modification of the main chain is preferably in the range of 3000 to 50,000. The reason for this is that it is difficult to obtain a desired temperature-melt viscosity and melt elastic modulus relationship when a main chain modified copolymer having a molecular weight smaller than the above range is used, and a main chain modified copolymer having a larger molecular weight than the above range is used. This is because the binder is less likely to be softened when used, and the fixability is often impaired.

In addition, as the component exhibiting rubber-like elasticity used in the present invention, polybutadiene or a copolymer containing butadiene as a constitutional unit, such as 1,4 trans-polybutadiene, 1,4 cis-pobutadiene, 1,2-polybutadiene is used. ,
Butadiene-acrylonitrile copolymer, butadiene-
A styrene copolymer, a butadiene-methyl methacrylate copolymer, a butadiene-methyl vinyl ketone copolymer, etc. can be used.

It should be noted that these rubber-like elastic components may have functional groups at their ends for imparting reactivity with molecules forming the main chain structure such as epoxy groups, amino groups, carboxyl groups, and hydroxyl groups. desirable.

The molecular weight of the component showing rubber-like elasticity used in the present invention and the amount of modification with respect to the main chain are arbitrary, but the molecular weight is 1000 to 50.
00, the modification amount is more preferably 5 to 30 wt% with respect to the weight of the main chain constituent components.

The reason why it is more desirable that the molecular weight of the rubber-like component used for the modification is about 1000 to 5000 is that the component showing rubber elasticity to the main chain is introduced in a block form to some extent after the main chain is modified to crystallize. The effect of inhibiting the polymer is large, and the main chain-modified copolymer obtained by such block copolymerization is relatively easy when an oligomer with a molecular weight of about 1000 to 5000 in which several rubber-like components are polymerized is used as a modifier. It depends on what you get.

In addition, the amount of modification is 5 to 30 wt% with respect to the weight of the main chain constituents.
% Is more desirable because the modification amount is 5w.
If it is t% or less, the effect of increasing the melt viscosity at the time of melting as described in the present invention is often difficult to appear, and if it is 30 wt% or more, a harmful effect due to the introduction of a rubber component, for example, the hardness of the copolymer after modification Is deteriorated, and when this is used as a toner binder, a problem such as difficulty in fine pulverization after kneading the toner is likely to occur.

The method for producing the main chain-modified copolymer is optional,
For example, when the prepolymer forming the main chain structure is a bisphenol epoxy resin, a bisphenol type epoxy resin oligomer, a bisphenol compound, butadiene and / or isoprene as a main monomer and an active hydrogen group capable of reacting with an epoxy group is 1.5 A main chain-modified copolymer can be obtained by reacting an oligomer containing an equivalent amount or more as an essential constituent component.

Similarly, in the case where the prepolymer that forms the main chain structure is polyester, an oligomer containing polyester oligomer and butadiene and / or isoprene as a main monomer and an active hydrogen group capable of reacting with a carboxyl group and / or a hydroxyl group in an amount of 1.5 equivalents or more. A main chain-modified copolymer can be obtained by reacting as an essential component.

Further, the prepolymer forming the main chain structure is a hydroxylated styrene-acryl or carboxylated styrene-
In the case of acrylic, by esterifying the styrene-acrylic oligomer with butadiene and / or isoprene as a main monomer, and an oligomer containing 1.5 equivalents or more of an active hydrogen group capable of reacting with a hydroxy group or a carboxy group as an essential component. A main chain modified copolymer can be obtained.

In addition, as a method of reducing the adverse effect caused by the introduction of the rubber-like component, a method of introducing a partially cross-linked structure between the main chain skeletons and using the effect of increasing the melt viscosity and the melt elastic modulus at the time of high temperature melting is used as an auxiliary Is also effective.

As a specific method, when the main chain skeleton is epoxy, a compound having active hydrogen capable of reacting with 3 equivalents or more of epoxy groups in one molecule, for example, N-aminoethylpiperazine, diethylenetriamine, triethylenetetramine. , A method of crosslinking between epoxy rings of the main chain skeleton with metaxylenediamine, diaminophenylmethane, etc.
When the main chain skeleton is a polyester chain, as a constituent monomer thereof, a compound having 3 equivalents or more of a carboxy group or a hydroxyl group in one molecule, for example, trimellitic acid, glycerin, pentaglycerol, pentaerythritol,
A method of containing an appropriate amount of 4,6-dioxy-2-methylbenzophenone or the like, and when the main chain skeleton is styrene-acryl, as a constituent monomer, 2 unsaturated bonds are contained in one molecule.
There is a method of adding an appropriate amount of a monomer having an equivalent amount or more, such as divinylbenzene.

In addition, when a nitrogen-containing compound is used as these cross-linking agent, by selecting the structure of the nitrogen-containing compound and the number of nitrogen atoms in the compound, it is possible to obtain a secondary advantage that the charge imparting ability of the binder can be accurately controlled. it can.

Further, the main chain modified copolymer subjected to main chain modification by introducing a component exhibiting rubber-like elasticity during the main inspection in the present invention, it is possible to use alone as a binder, other binder resin, That is, it is more preferable to use by blending with an epoxy resin, a styrene-acrylic resin, a polyester resin, a vinyl resin, or the like.

The first reason that the binder blend is desirable is that the relationship between the temperature-melt viscosity and the storage elastic modulus of the binder can be controlled relatively easily by blending the binder as described above.

The second reason is that the strength of the copolymer is inevitably reduced by modifying the main chain with a rubber-like elastic material as described above, and when the main chain-modified copolymer is used alone. This is because a reduction in toner crushing efficiency cannot be avoided. From this point of view, as a binder to be blended with the main chain modified copolymer, a resin having a certain hard and brittle property, such as an epoxy resin or a short chain linear diol and an aromatic dicarboxylic acid is condensed. A non-crosslinked polyester formed by polymerization is more desirable.

Further, the third reason is that the main chain-modified copolymer obtained by modifying the main chain by introducing a component showing rubber-like elasticity has a side chain containing a component showing rubber-like elasticity. Although the degree of decrease in the glass transition temperature is small by comparison, the glass transition temperature is slightly decreased due to the fact that it also has a component exhibiting rubber-like elasticity, and this main chain modified copolymer alone is used as a binder. This is because the toner may be blocked in a high temperature environment. From this viewpoint, it is desirable that the binder to be blended should have a high glass transition temperature while satisfying the above-mentioned temperature-melt viscosity and storage elastic modulus relationships. As a result of studies by the present inventors, the glass transition temperature of the binder blended with the main chain modified copolymer is desirably 70 ° C. or higher, and the amount thereof is 50 wt% of the entire binder.
% Is desirable.

The fourth reason is that blending binders having different skeleton structures may reduce the surface tension as compared with the case where each binder is used alone. This is because oligomers or polymers having polar groups to some extent are usually used as the binder for toner, and the polar groups are oriented by hydrogen bonds or the like to generate intermolecular attractive force and increase the surface tension. However, even in this case, by blending the binders having different skeleton structures, the orientation of the polar groups is disturbed and the intermolecular force is reduced, so that the surface tension is reduced.

According to the experience of the present inventors, at this time, the binder used for blending has a melting temperature of 125 ° C. or lower and a weight average molecular weight of 2
When a binder with a narrow molecular weight distribution with a weight average molecular weight of 0000 or less and a weight average molecular weight / number average molecular weight of 4.0 or less is used, the toner quickly dissolves when it is exposed to flash light. Is more suitable for.

Such a binder exhibiting physical properties can be found in non-crosslinked bisphenol type epoxy resins and non-crosslinked amorphous polyester resins.

Further, for the reason of preventing layer separation between binders at the time of melting in the fixing step, etc., when blending the binder,
It is desirable that the binders to be blended partially react with each other in a kneading step during toner production to form a partially crosslinked body.

The toner used in the present invention can be manufactured by a conventionally known method. That is, a binder resin, a colorant, an inorganic filler and, if necessary, a charge control agent and the like are added to a pressure kneader,
A desired toner can be obtained by kneading, melting and uniformly dispersing with a roll mill, an extruder or the like, finely pulverizing with a pulverizer such as a jet mill, and classifying with a classifier such as an air classifier.

In addition, various physical properties in this invention are measured using the following measuring methods.

(1) Surface tension Surface tension is measured at 200 ° C using a well-helmi method surface tension measuring instrument "Degeomatic ESB-V" (Kyowa Kagaku Co., Ltd.) with a constant temperature sample holder with temperature control range of ± 0.5 ° C. It is the value measured in.

(2) Melt viscosity / storage modulus The melt viscosity and melt modulus were raised in a nitrogen atmosphere using a cone-plate type dynamic viscoelasticity measuring device “MR-3 Liquid Meter” (Rheology Co., Ltd.). 50 ℃ at a speed of 10 ℃ / min
It is the value obtained by measuring the temperature rise from 1 to 250 ° C. The frequency at this time was 0.5 Hz.

(3) Melting point Melting point is the flow tester "Shimadzu Flow Tester CFT-500".
This is the value when a temperature rise flow test was performed using (Shimadzu Corporation) and the plunger was lowered by 4 mm. In addition,
The conditions of the temperature rising flow test are as follows.

・ Die 1mm × 1mmφ ・ Sample 1.5g pellet ・ Preheat temperature 60 ℃ ・ Preheat time 300sec ・ Raising rate 6 ℃ / min ・ Load 20kgf (4) Glass transition temperature The glass transition temperature is the differential scanning calorimeter "DSC-20".
(Seiko Denshi Co., Ltd.) was used to obtain the temperature rise endothermic curve at a temperature rise rate of 5 ° C./min.

[Examples] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited thereto.

First, the following 22 kinds of binders were experimentally manufactured as toner binders.

[Binder 1] Bisphenol A type epoxy oligomer, bisphenol A, terminal carboxy-modified butadiene are essential components, and polybutadiene is contained in the main chain structure of the epoxy resin.
wt% Budadiene modified epoxy resin [Binder 2] Bisphenol A type epoxy oligomer, bisphenol A, terminal carboxy modified butadiene-acrylonitrile are essential components, and butadiene acrylonitrile copolymer is 17 wt% in the main chain structure of the epoxy resin. Introduced Budadiene-acrylonitrile modified epoxy resin [Binder 3] Bisphenol A type epoxy oligomer, bisphenol A, terminal carboxy modified isoprene as essential constituents, and 22 wt% isoprene in the main chain structure of the epoxy resin.
Introduced isoprene-modified epoxy [Binder 4] Bisphenol A type epoxy oligomer, bisphenol A, terminal carboxy modified Budadiene-acrylonitrile, and novolak are essential components, and butadiene acrylonitrile copolymer is contained in the main chain structure of the epoxy resin.
wt% introduced partially crosslinked butadiene-acrylonitrile modified epoxy [Binder 5] Bisphenol A type epoxy oligomer, bisphenol A, terminal amino modified butadiene-acrylonitrile are essential components, and a butadiene acrylonitrile copolymer is contained in the main chain structure of the epoxy resin. Cross-linked butadiene-acrylonitrile-modified epoxy containing 10 wt% of [Binder 6] Bisphenol A-type epoxy oligomer, bisphenol A, terminal carboxy-modified butadiene-acrylonitrile, and meta-xylenediamine are essential constituents in the main chain structure of the epoxy resin. Partially cross-linked butadiene-acrylonitrile-modified epoxy with 13 wt% of butadiene-acrylonitrile copolymer introduced into [Binder 7] polyethylene terephthalate oligomer, terminal carbon An isoprene-modified epoxy in which 10 wt% of isoprene is introduced into the main chain structure of polyethylene terephthalate, with xy-modified isoprene as an essential component, [binder 8] ethylene glycol, 1,2-butylene glycol, polyoxyethylenated bisphenol A, terephthalic acid,
Isophthalic acid, a polyester oligomer having 2-methylterephthalic acid as an essential constituent and a terminal carboxy-modified butadiene-acrylonitrile as an essential constituent,
Partially cross-linked Budadiene-acrylonitrile modified polyester in which 10 wt% of butadiene acrylonitrile copolymer is introduced into the main chain structure of the above polyester [Binder 9] Terminal hydroxyl having styrene, divinylbenzene, n-butyl acrylate and hydroxymethyl acrylate as essential constituents. Cross-linked styrene-acrylic oligomer and partially cross-linked butadiene-acrylonitrile-modified styrene-acryl having essential carboxy-modified isoprene as essential components [Binder 10] Cross-linked styrene-acryl having styrene, divinylbenzene and n-butyl acrylate as essential components [Binder 11] Bisphenol A-type epoxy oligomer, a long-chain aliphatic carboxylic acid as an essential component, a long-chain aliphatic carboxylic acid grafted aliphatic carboxylic acid Epoxy [Binder 12] Bisphenol A-type epoxy oligomer, lactone-modified epoxy having polycaprolactone as an essential component and grafted with polycaprolactone [Binder 13,14] Polyoxyethylenated bisphenol A, polyoxybropylene bisphenol A, Eight types of resins were experimentally prepared as resins to be blended with the polyester main chain modified copolymer containing terephthalic acid and trimellitic acid as essential components.

[Binder 15,16,17] Bisphenol A type epoxy resin [Binder 18] Bisphenol A type epoxy partially crosslinked with aminocresol Crosslinked epoxy resin [Binder 19] Styrene and 2-ethylhexyl acrylate are essential constituents Styrene-acrylic resin [Binder 20] Polyester containing ethylene glycol, 1,2-butylene glycol, terephthalic acid, isophthalic acid and 2-methylterephthalic acid as essential constituents [Binder 21] Ethylene glycol, polyoxyethylenated bisphenol A , A polyester containing terephthalic acid, isophthalic acid, and trimellitic acid as essential constituents [Binder 22] Polyoxyethylenated bisphenol A, polyoxybromopyrenated bisphenol A, terephthalic acid, isophthalic acid, trimellitic acid Polyester Note as essential constituents, referred to physical properties of the resin in Table 3. Further, a toner was experimentally produced using the above resin and a mixture of the above resins as a binder. Table 4 shows the evaluation results of the toner using the single binder.
Shown in Table 5 shows the mixing ratio, physical properties, and evaluation results. In addition, trial production of any toner was performed by the following method.

First, 5 parts by weight of carbon black (Black Pearls L; manufactured by Cabot Corporation) as a colorant for the binder, Nigrosine dye (Bontron N-04; manufactured by Orient Chemical Co., Ltd.)
3 parts by weight was added, and the mixture was melted and kneaded at 130 ° C. for 30 minutes with a pressure kneader to obtain a toner mass. Then, the cooled toner lump was made into a coarse toner of about ˜2 mm by a rotoplex grinder.

Then, the coarse toner was pulverized and classified by using a pulverizer / classifier (IDS-3 type pulverizer / classifier; manufactured by Nippon Pneumatic Co., Ltd.) to obtain a toner A having a particle size of 5 to 20 μm.

The evaluation of the fixing property, the state of occurrence of voids, and the like were performed as follows.

First, 95 parts by weight of resin-coated magnetite powder (average particle size: 110 μm; manufactured by Kanto Denka Co., Ltd.) was used as a carrier, and 5 parts by weight of toner was added to this to prepare a developer.
It was performed using a FACOM-6715D laser printer that adopted the flash fixing method. At this time, the thickness of the toner on the recording paper was set to 10 to 15 μm. The setting condition of the fuser is the capacity
A 160 μF capacitor was used and the charging voltage was set to 2150 V. This was applied to a flash lamp to cause the flash lamp to emit light, and the toner on the paper was fixed.

In addition, the adhesiveness (Scotch mending tape, made by Sumitomo 3M) was lightly applied to the evaluation of fixing property, and an iron columnar block with a diameter of 100 mm and a thickness of 20 mm was adhered to the recording paper on the tape at a constant speed in the circumferential direction. After that, the tape was peeled off, and the ratio of the optical density after peeling to the optical density of the image before peeling the tape was expressed as a percentage to evaluate the fixability.

The optical density was measured with a Macbeth PCM meter. In the evaluation table, the ratio of optical density after tape peeling is
95% or more for ◎, 95 to 90% for ○, 90 to 75% for △, 75 to 30% for ×, less than XX
It was written with.

 In addition, the occurrence of voids was visually evaluated.

Furthermore, regarding the blocking property, the toner is 55 ° C,
After standing in a 30% RH environment for 3 hours, the blocking state was visually evaluated. Regarding the pulverizability, the processing amount of the toner using each binder in the jet pulverizer is the same as that of the toner using bisphenol A diglycidyl ether polymer, which is commonly used as the binder of flash fixing toner, in the jet pulverizer. Evaluation was made on the basis of the amount of treatment per unit time when pulverized.

The evaluation results are as follows: ◎ for a treatment amount equal to or higher than that of bisphenol A diglycidyl ether polymer, ◯ for treatment amount of 90% or more, △ for 80 to 90%, and 50 to 80%. ×, those having a processing amount less than that are indicated by xx.

As shown in Tables 3 and 4, the toner having a melt viscosity at 200 ° C and a storage elastic modulus of 100 poise and a binder having a density of 100 dyne / cm ² or more are excellent in the void prevention ability, while at 125 ° C.
Melt viscosity and storage elastic modulus at 5000 Poise, 40000dyn
Toner using a binder of e / cm ² or less has excellent fixability, and is excellent in fixability and void prevention ability No.2, No.1, No.8
Both low temperature melt viscoelasticity and high temperature melt viscoelasticity satisfy the scope of the present invention.

Furthermore, it has excellent void prevention ability among the above binders.
No.2, No.3, No.6, No.9 binder and No.16, No.18, No.20, No.21 which are excellent in fixing property and blocking property are blended as a binder to make toner. And the properties were evaluated (see Table 5).

[Advantages of the Invention] As described above, according to the present invention, it is possible to obtain a toner having excellent void resistance and fixability and excellent blocking resistance.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of void generation. In the figure, 1 ... Toner, 2 ... Recording paper, 3 ... Flash light, 4 ... Fixed image, 5 ... Void.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-129867 (JP, A) JP 63-193155 (JP, A) JP 58-144838 (JP, A) JP 2- 162355 (JP, A) International publication 86/05602 (WO, A)

Claims (3)

(57) [Claims] 1. A toner using a binder, wherein the binder has a surface tension at 200 ° C. of 30 dyne / cm or less, a melt viscosity of 100 poise or more, and a storage elastic modulus of 100 dyne / c.
A toner using a binder having a physical property value of m ² or more, a melt viscosity at 125 ° C. of 5000 poise or less, and a storage elastic modulus of 40,000 dyne / cm ² or less. 2. The binder, which has a melt viscosity at 200 ° C. of 30 poise or more and a storage elastic modulus of 50 dyne / cm ² or more,
And a binder having a melt viscosity of 3000 poise or less at 125 ° C and a storage elastic modulus of 35000 dyne / cm ² or less, and a melt viscosity at 200 ° C of 120 poise or more and a storage elastic modulus of 120 dyne.
/ cm ^{2 and} above and below 10000 poise melt viscosity at 125 ° C., the toner of claim 1, wherein the storage elastic modulus which is characterized by using as an essential component binder is 100000Dyne / cm ² or less. 3. As the binder, a functional group which exhibits rubber-like elasticity at room temperature to the first prepolymer or monomer forming the main chain structure of the binder by polymerization and which can react with the first prepolymer or monomer. 2. The toner according to claim 1, wherein the second prepolymer having 1.5 equivalents or more or a main chain-modified copolymer introduced with a monomer which becomes the same as the second prepolymer by polymerization is used.