JPH0544667B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a binder resin and a developer composition used for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc. It is.

[Conventional technology and problems]

As a conventional electrophotographic method, U.S. Patent No. 2297691
As stated in the specification of No. 2357809, etc.
A photoconductive insulating layer is uniformly charged, the layer is then exposed to light, and the charge on the exposed portions is dissipated to form an electrical latent image, which is then injected with toner. The image is visualized by attaching a colored, electrically charged fine powder called (developing process), and the resulting visible image is transferred to a transfer material such as transfer paper (transfer process), followed by heating, It consists of a step of permanently fixing (fixing step) by pressure or other suitable fixing method.

As described above, the toner must have the functions required not only in the development process but also in each process such as the transfer process and the fixing process.

Generally, toner is subjected to mechanical frictional force due to shearing force and impact force during mechanical operation in a developing device, and deteriorates while copying several thousand to tens of thousands of sheets.
To prevent such toner deterioration, it is best to use a strong resin with a large molecular weight that can withstand mechanical friction, but these resins generally have a high softening point and are suitable for non-contact fixing methods such as oven fixing and infrared fixing. With radiant fixing, the thermal efficiency is poor, so fixing is not sufficient.Also, with the contact fixing method, which has good thermal efficiency, even in the widely used heat roller fixing method, the temperature of the heat roller must be adjusted to ensure sufficient fixing. This not only causes problems such as deterioration of the fixing device, curling of paper, and increased energy consumption, but also causes a significant drop in production efficiency when producing toner by pulverizing such resins. do. Therefore, it is not possible to use a binder resin (binding resin) whose polymerization degree and even softening point are too high. On the other hand, in the heat roller fixing method, the heating roller surface and the toner image surface of the sheet to be fixed are in pressure contact, so the thermal efficiency is extremely high and it is widely used from low speeds to high speeds. When doing so, the toner adheres to the surface of the heating roller and is transferred to the subsequent transfer paper, etc.
A so-called offset phenomenon is likely to occur. To prevent this phenomenon, the surface of the heating roller is treated with a material with excellent mold release properties such as fluorine-based resin, and in addition, a mold release agent such as silicone oil is applied to the surface of the heating roller to completely prevent the offset phenomenon. are doing.

However, the method of applying silicone oil or the like is not preferable because it not only increases the size of the fixing device and increases the cost, but also makes it complicated, which can easily cause trouble.

Furthermore, as described in Japanese Patent Publication No. 55-6895 and Japanese Patent Application Laid-Open No. 56-98202, there is a method to improve the offset phenomenon by widening the molecular weight distribution width of the binder resin, but the degree of polymerization of the resin increases and the fixation becomes difficult. The temperature also needs to be high.

As a further improved method, Special Publication No. 57-493,
As described in JP-A-50-44836 and JP-A-57-37353, there is a method of improving the offset phenomenon by making the resin asymmetrical and crosslinking, but the fixing point has not been improved.

Generally, the minimum fusing temperature is between cold offset and hot offset, so the usable temperature range is
It is between the minimum fixing temperature and hot offset, and by lowering the minimum fixing temperature as much as possible and raising the minimum hot offset temperature as much as possible, it is possible to lower the usable fixing temperature and expand the usable temperature range, which saves energy. , high-speed fixing, and prevents paper from curling. In addition, since double-sided copying can be performed without trouble, copying machines have become more intelligent, and the temperature control of the fixing device has become more accurate.
There are many advantages such as relaxing the tolerance range.

Therefore, resins and toners with good fixing properties and offset resistance are always desired.

In general, polyester resins and styrene resins are often used as resins, and although it is desirable to use styrene resins economically, styrene resins inherently have a high minimum fixing temperature, and the resin composition and wax There was naturally a limit to the improvement achieved by adding .

[Means for solving problems]

The present invention was made to meet these demands, and its purpose is to prevent offset without applying an anti-offset liquid in the heat roller fixing method, and to provide a bonding property that allows fixing at a lower fixing temperature. Our purpose is to provide resins and developers.

Another object of the present invention is to provide a binding resin and a developer that can prevent offset without adding an offset preventive agent in a heat roller fixing system and can fix at a lower fixing temperature.

Another object of the present invention is to provide a binder resin and a developer that have good fluidity, do not cause blocking, and have a long life (hard to deteriorate).

The present inventors have arrived at the present invention as a result of intensive research to achieve the above object.

That is, the present invention provides a mixture of (a) styrene and/or styrene derivative and (b) at least one type of (meth)acrylic acid or ester thereof in a ratio of 20:80 to 95:5.
Add (c) alkenylsuccinic acid having 7 to 30 carbon atoms or its acid anhydride to the mixture (weight ratio) of (a) and (b) above.
It is obtained by copolymerizing by adding 0.05 to 10% by weight to the total amount of
A binding resin characterized by being made of a resin having a temperature of 160°C, and the binding resin being the main component of the binding resin,
An object of the present invention is to provide an electrophotographic dry developer composition containing this and a colorant as main components.

[Effect]

Examples of the styrene or styrene derivative (a) in the present invention include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene,
2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-
n-nonylstyrene, p-n-decylstyrene,
Examples include p-n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene.

Examples of the (meth)acrylic acid or ester thereof in (b) include acrylic acid, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, and tert acrylate. −
Butyl, amyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, decyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methoxyethyl acrylate, 2-hydroxyethyl acrylate, Glycidyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, methacrylic acid Isobutyl, tert-butyl methacrylate, amyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, decyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, methoxyethyl methacrylate, methacrylate Examples include 2-hydroxyethyl acid, glycidyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.

Examples of (c) alkenylsuccinic acids having 7 to 30 carbon atoms or their acid anhydrides include n-dodecenylsuccinic acid, isododecenylsuccinic acid, n-octenylsuccinic acid, isooctenylsuccinic acid, and acid anhydrides thereof. It will be done.

Among the components constituting the binding resin according to the present invention,
(a) Styrene or styrene derivative forms the main skeleton of the resin, and (b) (meth)acrylic acid or its ester adjusts the thermal properties such as the softening point of the resin, determines the electric charge, and adjusts the amount of charge. However, the compound (c) becomes a component that improves the minimum fixing temperature and offset resistance. Among these components, the ratio of (a) styrene or styrene derivative to (b) (meth)acrylic acid or its ester is 20:80 ~
The ratio is 95:5 (weight ratio), and the compound (c) is the same as (a).
It is added in an amount of 0.05 to 10% by weight based on the total amount of (b).
If the amount of the compound (c) is less than 0.05% by weight, the fixing properties cannot be improved, and if it exceeds 10% by weight, the storage stability as a toner decreases.

Furthermore, the softening point of the binder resin used in the developer composition of the present invention is 100 to 160°C using a Koka type flow tester; if it is too low, the offset resistance will be insufficient, and if it is too high, the fixing performance will be poor. It becomes insufficient.

The method for producing the binding resin of the present invention includes free radicals,
This is carried out by well-known addition polymerization reactions such as anionic and cationic polymerization methods.

Coloring agents used in the present invention include carbon black, acetylene black, phthalocyanine blue, permanent brown FG, brilliant first scarlet, pigment green B, rhodamine-B pace, and solvent red.
49, Solvent Red 146, Solvent Blue 35
etc. and mixtures thereof, and usually about 1 to 15 parts by weight are used per 100 parts by weight of the binder resin.

Examples of the magnetic material used in the present invention include alloys or compounds containing elements exhibiting ferromagnetism, such as ferrite and magnetite. 40～
It can be used by dispersing it in an amount of 70% by weight.

[Examples and effects]

Examples of the present invention will be described below, but the present invention is not limited to these examples.

All composition ratios shown in Examples are expressed in parts by weight.

Example 1 200 parts of toluene and 27 parts of isooctenylsuccinic acid are charged into a reactor equipped with a stirring device, a nitrogen inlet tube, a thermometer, a reflux condenser tube, and a dropping funnel, and the temperature is adjusted to 90°C. Styrene 900 under nitrogen flow
A mixture of 50 parts of 2-ethylhexyl acrylate, 23 parts of 2-hydroxyethyl acrylate and 15 parts of benzoyl peroxide was dropwise polymerized over 3 hours. After dropping, the temperature was raised to 100°C and aged for 4 hours. The temperature was gradually raised to 200°C while the pressure was reduced to 60 mmHg to distill off the toluene. The molten resin was taken out into a stainless steel vat, left to cool, and crushed to form a powder. Resin (Koka type flow tester softening point 124.4℃, Tg61.3
°C) was obtained. This softening point was measured using a Koka type flow tester (manufactured by Shimadzu Corporation) by heating a 1 cm ³ sample at a heating rate of 6°C/min with a plunger.
Apply a load of 20 kg/cm ² and extrude a nozzle with a diameter of 1 cm and a length of 1 cm. This draws a blungier drop-temperature curve (softening flow curve) of the flow tester, and calculates the height of the S-shaped curve. When h is the temperature corresponding to h/2, the softening point is defined as the temperature corresponding to h/2. 93 parts of the resin and 7 parts of carbon black (Regal 400R manufactured by Cabot) were mixed in a ball mill, kneaded using a hot roll, cooled, coarsely ground in a hammer mill, and then finely ground in a jet mill to obtain an average particle size of 14.2 microns after classification. I got the toner. The obtained toner was mixed with carrier iron powder and the amount of charge was measured using a blow-off measuring device, and it was found to be -17 μc/g.

91 g of the toner was mixed with 1209 g of carrier iron powder to prepare a developer, and a commercially available electrophotographic copying machine (the photoreceptor was
Se, the rotation speed of the fixing roller was 255 mm/sec, the heat roller temperature in the fixing device was varied, and the oil coating device was removed). A clear image with no omissions etc. was obtained.

When the fixing temperature was controlled between 140℃ and 220℃ and the image fixation and offset properties were evaluated, it was 155℃.
It was sufficiently fixed and no offset occurred.
After printing up to 20,000 images, background fog appeared.
Clear images were obtained with no black spots observed.

Here, the minimum fixing temperature means that the bottom surface is 15 mm x 7.5 mm.
A load of 500 g was placed on a sand eraser, and the image fixed through the fixing machine was rubbed back and forth 5 times. The optical reflection density was measured using a Macbeth reflection densitometer before and after rubbing, and the fixing rate was determined by the following definition. This refers to the temperature of the fixing roller when it exceeds 70%.

Fixing rate = Image density after rubbing / Image density before rubbing Example 2 200 parts of toluene and 40 parts of n-dodecenylsuccinic acid manufactured by Humphrey Co., USA were charged into the reactor of Example 1, and the temperature was raised to 90°C. Adjust. A mixed solution of 880 parts of α-methylstyrene, 50 parts of n-butyl acrylate, 30 parts of 2-hydroxyethyl methacrylate, and 15 parts of lauroyl peroxide was dropwise polymerized over 3 hours under a nitrogen stream. After dropping, raise the temperature to 100℃ and mature for 4 hours, then gradually raise the temperature to 200℃ and cut into 60mm
The pressure is reduced to Hg, the toluene is distilled off, the molten resin is taken out into a stainless steel vat, allowed to cool, and pulverized.
128.5℃, Tg65.2℃).

93 parts of the resin and 7 parts of carbon black (Regal 400R, manufactured by Kayabot Corporation) were mixed in a ball mill, kneaded, crushed and classified to obtain a toner having an average particle size of 14.4 microns. The amount of charge of the obtained toner is -
It was 20μc/g.

A developer was prepared by mixing 91 g of the toner with 1209 g of carrier iron powder, and an image was produced using the same evaluation machine as in Example 1. A clear image was obtained with no background smudges, bleeding, or missing solid black areas. Ta. When the fixing temperature of the fixing device was controlled and the image fixability and offset properties were evaluated, the image was fixed at 160°C and no offset occurred. When images were printed up to 20,000 sheets, clear images were obtained with no background fogging or missing solid black areas.

Example 3 200 parts of toluene and 15 parts of isododecenylsuccinic acid were charged into the reactor of Example 1 above, and the temperature was adjusted to 90°C.
Adjust to A mixed solution of 820 parts of styrene, 90 parts of 2-ethylhexyl acrylate, 50 parts of 2-hydroxyethyl methacrylate, 40 parts of diethylaminoethyl methacrylate and 15 parts of α,α'-azobisisobutyronitrile was added under a nitrogen stream. Polymerization is carried out dropwise over a period of 3 hours. After dropping, raise the temperature to 100℃ and mature for 4 hours.
While gradually raising the temperature to 200℃, reduce the pressure to 60mmHg and distill off the toluene. Take out the molten resin into a stainless steel vat, let it cool, and crush it to form a powdered resin (Koka flow tester softening point 127.6℃,
Tg66.5℃) was obtained.

93 parts of the resin and 7 parts of carbon black (Regal 400R, manufactured by Kayabot Corporation) were mixed in a ball mill, then kneaded, pulverized, and classified to obtain a toner having an average particle size of 14.3 microns. The amount of charge of the obtained toner is +
It was 20μc/g.

91 g of the toner was mixed with 1209 g of carrier iron powder to prepare a developer, and a commercially available electrophotographic copying machine (the photoreceptor was an organic photoconductor, the rotation speed of the roller was 255
mm/sec, the temperature of the heat roller in the fixing device was varied and the oil coating device was removed), and a clear image was obtained with no background smudges, smearing, or missing solid black areas. It was done. When the fixing temperature of the fixing device was controlled and the image fixability and offset properties were evaluated, it was found that the image was fixed at 160°C and no offset occurred. When images were printed up to 20,000 sheets, clear images were obtained with no background fogging or missing solid black areas.

Comparative Example 1 Using the reactor of Example 1, 900 parts of styrene, 80 parts of 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate were mixed in 200 parts of toluene at 90°C.
After dropping a mixture of 20 parts of benzoyl peroxide and 15 parts of benzoyl peroxide over 3 hours, the temperature was raised to 100°C and aged for 4 hours.
Thereafter, toluene was distilled off by the method of Example 1, and a powdered resin (softening point: 128.8°C, Tg: 67.4°C using Koka flow tester) was obtained after extraction and pulverization. A toner (charge amount was -19 μc/g) was prepared using the resin in exactly the same manner as in Example 1, a developer was prepared, and an image was produced using the same evaluation machine as in Example 1. A clear image with no background smudges, smearing, or black solid areas was obtained. When the fixing temperature of the fixing device was controlled and the image fixation and offset properties were evaluated, it was fixed at 180℃, but it was fixed at 140℃ to 220℃.
Offset occurred at all temperatures up to

Comparative Example 2 Using the reactor of Example 1, 890 parts of styrene and 100 parts of n-butyl acrylate were mixed in 200 parts of toluene at 90°C.
parts, 10 parts of divinylbenzene and lauroyl peroxide
15 parts of the mixed solution was added dropwise over 3 hours, and after aging at 100°C for 4 hours, toluene was distilled off using the method of Example 1.
After extraction and pulverization, a powdered resin (softening point: 129.6°C, Tg: 61.5°C using Koka flow tester) was obtained. A toner (charge amount was -18 μc/g) was prepared using the resin in exactly the same manner as in Example 1, a developer was prepared, and an image was produced using the same evaluation machine as in Example 1. However, clear images were obtained with no background smudges, smearing, or missing solid black areas. When the fixing temperature of the fixing device was controlled and the image fixability and offset properties were evaluated, no offset occurred up to 220°C, but the fixing temperature was 190°C.

As can be seen from the Examples and Comparative Examples described above, it is clear that the developer composition of the present invention provides clear images, is excellent in durability, has good offset resistance, and can be fixed at low temperatures.

Claims (1)

[Claims] 1. (a) Styrene and/or styrene derivatives.
(b) A mixture of at least one type of (meth)acrylic acid or its ester at a ratio of 20:80 to 95:5 (weight ratio), and (c) alkenylsuccinic acid having 7 to 30 carbon atoms or its acid anhydride. is obtained by copolymerizing 0.05 to 10% by weight of the above total amount of (a) and (b), and is characterized by being composed of a resin having a softening point of 100 to 160°C in a Koka type flow tester. Binding resin for electrostatic image development. 2. In an electrophotographic dry developer composition containing a binding resin and a colorant as main components, the main components of the binding resin are (a) styrene and/or a styrene derivative and (b) at least one 20:80 to 95:5 (weight ratio) with (meth)acrylic acid or its ester
To the mixture, (c) alkenylsuccinic acid having 7 to 30 carbon atoms or its acid anhydride is added in an amount of 0.05 to 10% by weight based on the total amount of (a) and (b) above, and obtained by copolymerization. ,
A dry developer composition for electrophotography, characterized in that it is a resin having a softening point of 100 to 160°C.