JPS5845022B2 - Heat-fixing developing toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner for developing electrostatic latent images for electrophotography, electrostatic recording or electrostatic printing, or magnetic latent images for magnetic recording. This invention relates to toner for mold development.

In general, as methods for fixing dry toner images, there are known pressure fixing methods, heat fixing methods, and heat pressure fixing methods that use pressure and heat, but among these methods, the structure of the fixing device used is relatively The heat fixing method is widely used because it is simple and the toner can be manufactured easily.

Naturally, the heat-fixing type developing toner used in such a heat-fixing method requires little thermal energy;
It is desirable that the fixing speed is high so that fixing can be done within a short time, that the image is not disturbed by fixing, and that the image after fixing has physical properties such as being sufficiently robust and having high scratch resistance. It is also desirable that the material be easily manufactured.

Conventionally known heat-fixable developing toners generally require a large amount of thermal energy, have a low fixing speed, and have drawbacks such as the image after fixing does not have sufficient scratch resistance.

In order to eliminate such drawbacks, research has been carried out focusing on, for example, lowering the softening point of the resin component of the toner, or lowering the melt viscosity of the toner, which is a major factor in heat fixability. Ta.

However, there is a limit to lowering the softening point due to storage considerations of the toner, and in order to lower the melt viscosity of the toner, it is possible to use a resin with a small melt viscosity as the resin component of the toner. Such resins are usually low molecular weight resins and are therefore fragile, and as a result, the durability of the toner and the strength of images after fixing, such as scratch resistance, are low and cannot be put to practical use.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-fixable developing toner that can perform the required fixing by heating for a short time, and therefore can increase the fixing speed.

Another object of the present invention is to provide thermal fixing that has favorable physical properties such as toner durability, no image disturbance caused by fixing, and sufficiently robust and scratch-resistant images after fixing. To provide a toner for mold development.

Still another object of the present invention is that it can be easily manufactured by a manufacturing method that includes a step of pulverizing a raw material block.

An object of the present invention is to provide a heat-fixable developing toner having appropriate hardness and elasticity.

In the present invention, in a developing toner composed of a resin component and a colorant component, the resin component is composed of an ethylene copolymer and a low molecular weight resin, and the low molecular weight resin is a polyterpene resin, an epoxy resin, etc. One or more of resin, petroleum resin, and styrene resin.

Such a developing toner has extremely excellent characteristics as a heat fixing type developing toner.

That is, the toner of the present invention melts rapidly when heated at a relatively low temperature, and has appropriate viscosity in this melted state, so it is suitable for printing onto recording materials such as photosensitive paper and transfer paper on which toner images are to be fixed. The toner adheres or sticks to the toner and does not flow, and is then cooled and solidified within a short period of time to fix it.Furthermore, this fixed toner (hereinafter referred to as "fixed toner") has excellent strength with high scratch resistance. As a result, the toner of the present invention produces clear, undisturbed, well-fixed, long-lasting images on large surfaces.
It can be formed by short-time heat fixing treatment.

Examples of ethylene copolymers that can be used in the present invention include ethylene-vinyl acetate copolymers, partial hydrolysates of ethylene-vinyl acetate copolymers, graft combinations of ethylene-vinyl acetate copolymers and vinyl chloride, A graft combination of a partial hydrolyzate of ethylene-vinyl acetate copolymer and an unsaturated organic acid, ethylene alkyl acrylate, ethylene meta-alkyl acrylate, or ethylene-vinyl chloride copolymer, and one or more of these are used. be able to.

This ethylene copolymer has adhesive properties, abrasion resistance, impact resistance and elasticity, and also has a relatively high softening point and a relatively high melt viscosity.

According to conventional wisdom, using such an ethylene copolymer as a resin component of a toner increases the toner's softening point and melt viscosity, and is therefore undesirable for obtaining a heat-fixable toner. It was considered.

However, as in the present invention, when the above-mentioned low molecular weight resin and this ethylene copolymer are blended and used in the proportions stated in the claims, the softening point and melt viscosity of the toner are those of the ethylene copolymer. It is hardly affected by
Practically speaking, it is dominated by the low molecular weight resins mentioned above.

For this reason, the toner of the present invention melts quickly and also quickly penetrates and fixes on the recording medium.

In addition, in such a fixed toner, the physical properties of the ethylene copolymer are significantly manifested, and the physical properties of the low molecular weight resin are suppressed or hidden, resulting in excellent scratch resistance, surface durability, etc. is obtained.

According to the toner of the present invention, in addition to the excellent heat fixing properties as described above, the elasticity of the ethylene copolymer makes the toner less likely to be crushed. The toner particles are not crushed during the process, the process of adhering to the surface on which the latent material is formed, the process of transferring to the transfer paper, etc. Therefore, the durability of the toner is improved, and since no fine powder is generated, the image does not become smudged. When a transfer step is included, stains on the master are significantly reduced.

The ethylene copolymer is
) It is preferable that the softening point is within the range of 40 to 100°C and the Shore D hardness is 20 or more.

The low molecular weight resin is selected from the resins mentioned above, and examples of petroleum resins include synthetic rosin ester resin, synthetic terpene resin, α-methylstyrene-vinyltoluene copolymer, cyclo Hydrogenated products of pentadiene resin, alicyclic hydrocarbon resins, aliphatic hydrocarbons
Mention may be made of aromatic hydrocarbon copolymers.

The molecular weight of the low molecular weight resin is 600 to 3000.
Moreover, the softening point according to the ring and ball method is 50 to 180'
C is preferred.

The ratio of the ethylene copolymer to the total resin components is 3% by weight or more and is below the 40 weight plate, and the ratio of the low molecular weight resin to the total resin components is 30 weight % above the plate.

That is, if the content of the ethylene copolymer is less than 3% by weight, no effect can be obtained substantially by including the copolymer, and if it exceeds 40% by weight, the heating energy for fixing will be greatly increased. The same applies when the content of low molecular weight resin is less than 30% by weight.

On the other hand, in order to produce a developing toner, it is advantageous in various respects to use a method that includes a pulverization step.

However, in toners containing more sensitive resin components such as ethylene copolymer and low-molecular-weight resin, the side impact properties of the ethylene copolymer are noticeable, so it is difficult to remove the raw material agglomerates by normal means. It becomes difficult to grind properly.

In the present invention, in order to eliminate the above drawbacks,
In addition to the ethylene copolymer and low molecular weight resin, polyvinyl acecool resin is added to form the resin component of the toner for heat fixing developer.

By including the polyvinyl acecool resin in the resin component in this manner, the toner can be easily pulverized without impairing the above-mentioned excellent properties, and a toner having a desired particle size can be efficiently produced.

Therefore, in the present invention, an ethylene copolymer, a low-molecular-weight resin, and a polyvinyl acetal resin are kneaded together with a coloring agent while heating, solidified by cooling, the resulting raw material lumps are pulverized, and the pulverized material is classified. 5-20μ after processing
Particles with a particle size of

In the above, the raw material agglomerates may be crushed by crushing the agglomerates, then coarsely crushing them with a pulverizer such as a Wiley pulverizer, and pulverizing the crushed material with a pulverizer such as a hammer mill.

Polyvinyl acecool resin is produced by acetalizing polyvinyl alcohol and a saturated aldehyde having 1 to 3 carbon atoms in the presence of an acid or alkali, and the degree of acetalization depends on the type of aldehyde used, It varies depending on the amount added, amount of catalyst, etc.

In the present invention, it is particularly preferable to use polyvinyl butyral.

The polyvinyl acetal resin is preferably contained in an amount of 2.5 to 25 weight percent based on the total of the ethylene copolymer and the low molecular weight resin.

The developing toner of the present invention contains a coloring agent in addition to the resin component described above.

As this colorant, carbon black and other pigments produced by various methods can be used.

Further, according to the present invention, it is possible to provide a toner for heat fixing development that is used as a so-called two-component developer that is charged by friction with a carrier, and also toner that can be used as a one-component developer by containing magnetic powder. A heat-fixable developing toner used as a developer can be provided.

In this case, the magnetic powder can have the function of a coloring agent.

Examples of the present invention will be specifically described below, but the present invention is not limited thereto.

Also, parts indicate parts by weight.

The above substances are mixed, kneaded with a two-roll mixer while heating, cooled to obtain a raw material block, which is crushed and coarsely crushed with a Wiley crusher to obtain a granulated body of 12 meshes or less, and further This was pulverized by a hammer mill to obtain a powder having a mesh size of 400 or less, and this powder was classified to produce a toner having a particle size of 5 to 20 μm.

Note that oil black BS is a charge control agent.

5 (Bi' and 200 to 300
The electrostatic latent image formed on the electrophotographic light-sensitive material using zinc oxide is developed by mixing the carrier 1 ky made of mesh iron powder and developing the electrostatic latent image formed on the electrophotographic light-sensitive material using zinc oxide. It was transferred onto paper and fixed using a heat fixing device.

Further, the formation, transfer and fixing of the electrostatic latent image were repeated using the same photosensitive material.

The fixed image obtained in the 1000th copying process is
The image was as clear and excellent as that obtained in the initial copying process, the transfer rate was 91 times higher than the weight plate, and almost no stains were observed on the surface of the photosensitive material at this time.

Further, the copying process was repeated up to 20,000 times using the same developer, and a good fixed copy image was obtained until the end.

A toner was produced using the above materials in the same manner as in Example 1, and a developer was prepared from this toner in the same manner as in Example 1 and a copying test was conducted.

The copying process was repeated up to 30,000 times, and all the fixed copies obtained were of excellent quality.

Example 3 Among the above substances, first, ethylene-vinyl acetate copolymer and polyvinyl butyral resin were heated and melted and kneaded, then other substances were added and further kneaded to obtain a raw material block, and this was carried out. After pulverization in the same manner as in Example 1, the pulverized bodies were dispersed in hot air at a temperature of about 250'C to make the particles spherical, and the particles were classified to have a particle size of 10 to 20 μm.
A magnetic toner was produced.

Incidentally, ethylene bisstearamide is a mold release agent.

A developer was prepared by mixing 0.1 weight range of hydrophobic silica fine powder with the toner thus obtained, and a copying test was performed using an electrostatic transfer type electronic copying machine using this developer.

When copying is repeated 1000 times, the contamination density of the electrophotographic photosensitive material master using zinc oxide is 0.0 in terms of optical reflection density.
It was 05.

Moreover, the obtained copied image was excellent.

The above substances were kneaded while heating and cooled to obtain a raw material block, which was crushed and classified in the same manner as in Example 1, and particles with a particle size of 10 to 20 μm were taken out to produce a magnetic toner.

However, it was observed that in the pulverized body before classification, regular particles between several particle diameters were mixed without being pulverized.

A copying test was conducted in the same manner as in Example 3 using the obtained toner.

When copying was repeated 1000 times, the contamination density of the master was 0.08 in terms of optical reflection density.

The reproduced image was also satisfactory in terms of sagging.

A toner was manufactured using the above materials in the same manner as in Example 1, a developer was prepared, and a copying test was conducted.

When the number of copies exceeds 10,000 times, the image quality of the copied image deteriorates, making it impossible to obtain a copied image of practical value.

A magnetic toner was produced using the above materials in the same manner as in Example 3, a developer was prepared, and a copying test was conducted.

In this copying test, the contamination density of the master when copying was repeated 1000 times was 0.3 in terms of optical reflection density.

The above materials were kneaded while heating and cooled to obtain a lump.

This mass had too much secondary bombardment and could not be coarsely crushed by the Wiley crusher.

Further, the five toners obtained in Examples 1 to 5 above were designated as T1 to T5, respectively, and the two toners obtained in Comparative Examples 1 and 2 were designated as CI and C2, respectively, and these toners were subjected to a fixing property test and Melting property tests were conducted.

In the fixing property test, a large number of toner images transferred with the toner to be tested are produced using a transfer type electronic copying machine, and the images are passed through a space between hot plates maintained at a temperature of 400'C at various speeds. The quality of fixing was determined by rubbing the heat-treated image with paper and observing the disturbance of the image, and the highest critical passing speed that would not cause any practical problems was determined.

The results are shown in Table 1.

If the passing speed exceeds the maximum critical speed mentioned above, toner will adhere to the abrasion paper and smearing will occur on the image.If the passing speed is about 5 crrL/sec higher than the maximum critical speed, almost no fixing will be achieved, and the toner will adhere to the abrasive paper and the image will bleed. The image is severely distorted or disappears.

Images processed at passing speeds 1-2 crfL/sec or more lower than the maximum critical speed mentioned above were more completely fixed, and the same was true for fallen toner.

As is clear from the results of this fixing property test, the toner of the present invention achieves sufficient fixation with a considerably shorter heating time than the conventional heat-fixing developing toner represented by Toner C1 or C2. Therefore, the fixing speed can be increased, and as a result, for example, the throughput of an electronic copying machine can be increased.

In addition, in the melting property test, each sample toner was placed on aluminum foil at a constant density using a melting point meter (manufactured by Mitamura Riken Kogyo Co., Ltd.), and the temperature of the aluminum foil was adjusted at a rate of 5°C/sec. The temperature was increased at a constant rate, and the temperature at which the toner particles began to melt and the particles began to become spherical due to surface tension, ie, the spheroidization temperature, and the temperature at which adjacent particles coalesced, ie, the coalescence temperature, were measured.

The results are shown in Table 2. As is clear from the results of this melting property test, the toner of the present invention has a melting point that is equal to or even lower than that of conventional heat-fixable developer toners, even though it contains an ethylene copolymer with a high melting point. Therefore, as described above, sufficient fixing can be achieved by short-time heating, and the image after fixing has sufficient vibration damping properties due to the ethylene copolymer and is excellent in durability.

Furthermore, as is clear from the comparison between Examples 1 and 2 and Comparative Example 1, when the toner of the present invention is used as a two-component developer, the strength of the toner is high because it contains an ethylene copolymer, and the carrier The master will not be crushed due to friction with other objects, and the number of times the master can be used repeatedly in the image forming process including the transfer process can be greatly increased.

Furthermore, as is clear from the comparison between Examples 3 to 5 and Comparative Example 2, even when the toner of the present invention is used as a one-component developer, the toner particles are difficult to crush, making it difficult to generate fine powder. Result - In an image forming process including a transfer process using a component-based developer, contamination of the master used can be suppressed to an extremely low level.

Furthermore, as shown in Comparative Example 3, when an ethylene copolymer is used as the resin component, unless polyvinyl acecool resin is also used as the other resin component, the lumps can be crushed by ordinary crushing means. Even if pulverization is possible, as shown in Examples 4 and 5, regular coarse particles are generated and the desired pulverization cannot be carried out. cannot be manufactured.

However, by including a polyvinyl acetal resin together, developing toners can be advantageously produced as shown in Examples 1 to 3.

Although this polyvinyl acecool resin makes it easier to crush raw material lumps, it
As shown in Figure 2, there is no particular effect on fixing properties.

As described in detail above, according to the present invention, it is possible to provide a developing toner that can be fixed by short-time heat treatment and has sufficiently strong and durable images after fixing. Because of its high speed, it can be used, for example, in an electronic copying machine to greatly improve the performance of the copying machine, and the developing toner can be advantageously manufactured by a manufacturing method that includes a pulverization process, and furthermore, the toner particles can be Since the durability is increased, by using it as a developer in an image forming process including a transfer process, contamination of the master can be reduced and its useful life can be extended.

Claims (1)

[Claims] 1 Consists of a resin component and a coloring component, the resin component comprising:
At least one low molecular weight resin selected from the group consisting of polyterpene resins, epoxy resins, petroleum resins and styrene resins, with a weight of φ30 or more and a buoy cut softening point of 40 to 1
1. A heat-fixing type developing toner comprising a plate having 3 to 40 ethylene copolymer and a plate having 2.5 to 25 weight of polyvinyl acetal resin. 2. The ethylene copolymer is an ethylene-vinyl acetate copolymer, a partial hydrolyzate of an ethylene-vinyl acetate copolymer,
Graft combinations of ethylene-vinyl acetate copolymers and vinyl chloride, graft combinations of partial hydrolysates of ethylene-vinyl acetate copolymers and unsaturated organic acids, polyethylene alkyl acrylates, polyethylene meta-alkyl acrylates, and ethylene-vinyl acetate copolymers. The heat-fixable developing toner according to claim 1, which is at least one selected from the group consisting of vinyl chloride copolymers. 3 Petroleum resins include synthetic rosin ester resins, synthetic terpene resins, α-methylstyrene-vinyltoluene copolymers, hydrogenated products of cyclopentadiene resins, alicyclic hydrocarbon resins, and aliphatic hydrocarbons-aromatic hydrocarbons. The heat-fixable developing toner according to claim 1, which is selected from the group consisting of copolymers. 4. The heat-fixable developing toner according to claim 1 or 2, wherein the ethylene copolymer has a Shore D hardness of 20 or more. 5. The toner for heat fixing type development according to claim 1, wherein the low molecular weight resin has a molecular weight of 600 to 3000 and a softening point of 50 to 180°C by the ring and ball method. 6. The heat-fixable developing toner according to claim 1, 2, 3, 4, or 5, which contains magnetic powder. 7 Claim 1 in which the colorant component is magnetic powder
The heat-fixing type developing toner described in Section 1.