JPH0311361A - Capsule toner for image recording - Google Patents

Abstract

PURPOSE:To improve pressure fixability and to prevent the blocking and filming of the toner by forming the capsule toner of a soft core material essentially consisting of a specific binder resin, etc., and a film-like hard shell material applied around this core material. CONSTITUTION:The two-component developer consisting of a mixture of a magnetic carrier and the insulating toner consists of the soft core material contg. a coloring agent and the binder resin as its essential components and the film-like hard shell material, for example, acrylic resin, applied around this core material. The binder resin for the core material is the bifunctional amide monomer expressed by following formula: Y-R-Y, where Y denotes an amide group-contg. component having, as a substituent, respectively at least one hydroxyl groups, and which may be the same or different; R denotes a satd. or unsatd. straight or branch chain or cyclic group combining Y. The pressure fixability is improved in this way and the generation of blocking and toner filming is obviated.

Description

[Detailed Description of the Invention] [Summary] Regarding a capsule toner for image recording, it is an object of the present invention to provide a capsule toner that has excellent pressure fixing properties and can prevent toner blocking and filming on the carrier surface. The core material is composed of a soft core material containing a one-color daisy and a binder resin as main components, and a film-like hard shell material coated around the core material, in which case the binder resin for the core material is expressed by the following formula: A bifunctional amide monomer represented by R represents a saturated or unsaturated linear or branched chain group or a cyclic group that binds the Y component.

[Industrial application field]

The present invention relates to a capsule toner for image recording.

More specifically, the present invention relates to a capsule toner for image recording useful in magnetic brush developers used in electrophotography, particularly in two-component developers comprising a mixture of a magnetic carrier and an insulating toner. Here, the capsule toner refers to a toner in the form of a so-called capsule (a composite structure consisting of a core material containing a colorant and a binder resin as main components and a shell material coated around the core material). .

(Prior Art) As an electrophotographic method, the method described in U.S. Pat. No. 2,297,691 and others is well known. An electrical latent image is formed by imparting a uniform electrostatic charge and irradiating a light image onto the electrostatic latent image carrier using various means, and then the latent image is developed using a colored fine powder called a toner. After visualizing and transferring the toner image to paper etc. as necessary,
Printed matter is obtained by fixing using pressure, heat, light, etc.

As a developing method using the above-mentioned toner, a magnetic brush developing method described in US Pat. No. 2,786,439 and the like is in particular widely used. To explain the magnetic brush development method in detail, a magnetic developer is used in which a magnetic carrier and a toner are mixed and stirred and frictionally charged to have opposite polarities. By rubbing the surface of the electrostatic latent image carrier, only the toner is separated and adhered by electric attraction, and the electrostatic latent image is developed. Conventionally, the magnetic developer is a so-called two-component magnetic developer, specifically, the carrier has an average particle size of 1.
Magnetic powder such as iron powder, ferrite powder, magnetite powder, etc., or resin-coated powder of these magnetic powders is used as the toner, and a colorant etc. is dispersed in a binder resin made of a natural or synthetic polymeric substance. Non-magnetic insulating powder pulverized to an average particle size of about 10 s is commonly used.

Conventionally, since pressure fixing uses only pressure, it has been necessary to use a soft resin such as polyethylene wax as the binder. However, when a soft resin is used, toner particles tend to adhere to each other and agglomeration phenomena such as blocking and caking occur even when the toner is being stored or being used after being supplied to a toner hopper. When this phenomenon occurs, the fluidity of toner deteriorates, and smooth supply from the toner hopper becomes impossible.

Furthermore, with two-component developers, while stirring with the carrier in the developing machine, the toner adheres to the carrier surface (filming), the amount of charge decreases with stirring time, and finally the toner stops being charged. There's a problem.

On the other hand, if a hard resin is used, blocking and carrier filming will not occur, but the pressure fixing properties of the toner will deteriorate.

Therefore, in order to solve these problems, it has been proposed to use a capsule toner in which a soft resin (core material) is coated with a hard resin (grain It). In fact, when a capsule toner is used, although the fixing performance deteriorates to some extent, it is possible to considerably prevent toner aggregation and carrier filming from occurring. However, there remains a need to provide improved capsule toners.

[Problem to be solved by the invention]

An object of the present invention is to have excellent pressure fixing properties, and
An object of the present invention is to provide a capsule toner capable of preventing toner blocking and filming on the surface of a carrier.

[Means for Solving the Problems] According to the present invention, the above object is achieved by forming a soft core material containing a colorant and a binder resin as main components and a film-like hard shell material coated around the core material. In this case, the binder resin for the core material is a bifunctional amide monomer represented by the following formula: This is achieved by a capsule toner for image recording, characterized in that R represents a saturated or unsaturated linear or branched chain group or a cyclic group bonding the Y component. be able to.

The amide monomer used as the binder resin in the core material of the capsule toner of the present invention is as described above.
It is functional and each amide group component Y has at least one hydroxyl group, preferably a total of two hydroxyl groups. Care must be taken that too many hydroxyl groups may result in unacceptably high tack, which will interfere with the dry process. The group R that connects the two Y components may be a saturated or unsaturated group, such as a linear or branched group, such as an alkyl group or an alkylene group, or a cyclic group, such as an aromatic group such as a phenylene group. It can be a hydrocarbon group, an alicyclic hydrocarbon group such as a cyclohexylene group, etc.

These groups R may be substituted as necessary.

A preferred example of the amide monomer useful as the binder resin for the core material is as follows: (n = 3 to 30
) (n=3-30) (n=3-30) The binder resins described above can be used in the core material in amounts common in this technical field. Although the amount is not particularly limited, it is generally preferred to be about 90-96% by weight, based on the total amount of core material.

The core material, as will be understood, corresponds to the conventional toner itself and can therefore contain various components in addition to the binder resin described above. The main components are a coloring agent as the main component and additives such as charge control agents (dyes) and waxes. The core material can be prepared in the same manner as conventional toner particles.

The shell material of the capsule toner of the present invention can be any material that can be coated around the core material in the form of a hard film and does not adversely affect the operation of the core material. Useful shell materials include, for example, acrylic resins such as polymethyl acrylate, polymethyl methacrylate, and the like. In order to uniformly fuse the shell material to the surface of the core material, the particle size of the shell material is set to 1 of the particle size of the core material.
It is preferable to have a particle size of 1/0 or less.

When polymethyl methacrylate (PMMA) is used as the shell material, the average particle size of PHMA is preferably 1 μm or less in order to obtain a uniform film.

Preparation of capsule toners can be carried out according to various techniques. Advantageously, the shell material is electrostatically attached to the surface of the core material that has already been prepared, and the surface of the core material is fused and coated with the shell material in the form of a film by application of mechanical energy, thermal energy, or the like. More specifically, taking PHMA as a shell material as an example, first, a certain amount of core material and P? 1MA is stirred and mixed at high speed to electrostatically adhere PMMA to the surface of the core material. Next, an impact force is applied to cause the toner with PMMA attached to collide with the plate at high speed.
A capsule toner is formed by causing the PMMA to fuse to the toner surface using impact energy.

After preparing the capsule toner, it is mixed with a carrier to prepare a developer. Any magnetically sensitive material is suitable as the carrier, including metals such as iron and nickel, metal oxides, and alloys.

[For production]

In the pressure fixing method, it is necessary to use a soft resin as a binder in order to improve fixing performance.

However, when this is used, a bronking phenomenon occurs in which toner particles gather together during stirring in a developing machine, making it impossible to maintain normal printing characteristics. In addition, in two-component developers,
Toner filming occurs, in which the toner is fused to the carrier surface, and the toner is no longer charged.

On the other hand, if a hard resin is used, good pressure fixing properties cannot be obtained.

In order to solve these problems, the present invention uses a capsule toner in which the surface of a core material that has excellent pressure fixing properties is uniformly coated with a shell material that has excellent charging properties. , blocking, and toner filming do not occur.

〔Example〕

Next, the present invention will be explained with reference to some examples and comparative examples. Note that it should be understood that the present invention is not limited to these examples.

Susei LfLL The following toner components were mixed in the stated amounts.

Amide monomer m: (n=18) 94 parts by weight This mixture was melt-kneaded and then pulverized and classified to give an average particle size of 11-
An insulating toner was obtained.

Next, 77 parts by weight of this toner (core material) was added to PMMA.
MP-1451 (shell material) with an average particle size of 0.15
(Soken Chemical) 23 parts by weight was added to Henshir mixer (Dan-IO).
B type, Mitsui Miike Manufacturing Engineering] performs mixing and stirring and PM? 1A was electrostatically deposited on the toner surface. Next, PMMA was fused to the surface of the toner using the above mixture by impact encapsulation in a high-speed air stream, and a capsule toner having an average particle size of 11.5E+ was obtained.

(1) Fixability test Powder images of the prototype capsule toner with different toner layer thicknesses (15 to 341 M) were created on plain paper using a mini-developing machine, and these were passed through the pressure fixing section of a pressure fixing tester. A fixed image of the toner was obtained. Note that the linear pressure of the pressure fixing section of this tester is 15 kg/cm, and the nip length is 0.6 + nm. Next, apply adhesive tape (Scotch Mending Tape, manufactured by Sumitomo 3M) to this fixed image under a constant load (1 kg).
Attach the tape at
Fixability was evaluated.

(Results) Regardless of the thickness of the toner powder image after development, the fixing rate was 80.
% or more, showing good pressure fixing properties.

(2) Change in charge amount with stirring time A prototype capsule toner and a resin-coated ferrite carrier (average particle size Loom) were mixed at a toner concentration of 4 wt %, and stirred using a ball mill.

The developer was sampled during stirring for 10 minutes, 1 hour, 50 hours, and 100 hours, and the amount of charge at each time was measured.

(Results) The amount of charge upon stirring for 10 minutes was 11 μC/g, and the amount of charge of 11 μC/g was maintained even after stirring for 100 hours.

(3) Presence or absence of toner filming The presence or absence of toner filming was checked three times by observing the surface condition of the carrier after stirring for 100 hours using a SEM image.

(Results) No toner fusion was observed on the carrier surface, and no toner filming occurred.

(4) Presence of blocking The prototype capsule toner was left in an environment of 60'C130% by weight for several days, but no blocking occurred between the toners.

Comparison (1) Evaluations (1), (2), (3), and (4) of Example 1 were conducted in the same manner only for the core material of the capsule toner of Example 1.

(1) The fixing rate was as good as 95% or more regardless of the thickness of the powder image.

(2) When stirred for 10 minutes, it is 6μC/g, but when stirred for 1 hour, it becomes 2μC/g, and after 100 hours it is 0.9μC.
/g, so there was almost no charge.

(3) Toner was fused to the surface of the carrier after stirring for 100 hours, and significant toner filming was observed.

(4) Although there was almost no blocking, there was some buildup of toner particles.

1 garden ±1 The following toner components were mixed in the stated amounts.

Amide monomer m: (n=18) 94 parts by weight Dye Nioil Plaque BY (manufactured by Orient Chemical Co., Ltd.) 3 parts by weight Carbon black: Black Pe5rls L (manufactured by Cabot Corporation)
3 parts by weight of this mixture was melt-kneaded and then pulverized and classified to obtain an insulating toner having an average particle size of 11 μm.

Next, 77 parts by weight of this toner (core material) was added to PMMA.
(shell material) MP-1451 with an average particle size of 0.15
(Soken Chemical) 23 parts by weight was added to a Funschel mixer (FM-I).
OB type, Mitsui Miike Seisakusho Engineering) was used to electrostatically adhere PMM^ to the toner surface by mixing and stirring.Next, the mixture was subjected to impact encapsulation in a high-speed air flow to fuse PMMA to the toner surface. The average particle size was 11. An In capsule toner was obtained.

(1) Fixability test Powder images of the prototype capsule toner with different toner layer thicknesses (15 to 34 nm) were created on plain paper using a mini-developing machine, and these were passed through the pressure fixing section of a pressure fixing tester. A fixed image of the toner was obtained. In addition, the linear pressure of the pressure fixing part of this test machine is 15 kg/am, and the nimble length is 0.6 peng. next,
Adhesive tape (Scotch Mending Tape, manufactured by Sumitomo 3M) is applied to this fixed image with a constant load (1 kg), and it is peeled off at 2.5 cu+/S. The fixing properties were evaluated.

(Results) Regardless of the thickness of the toner powder image after development, the fixing rate was 80.
% or more, showing good pressure fixing properties.

(2) Change in charge amount with stirring time Prototype capsule toner and resin-coated ferrite carrier (average particle size 100, 1/Il+) toner concentration 4W
They were mixed at t% and stirred using a ball mill.

The developer was collected during stirring for 10 minutes, 1 hour, 50 hours, and 100 hours, and the amount of charge at each time was measured.

(Results) The amount of charge upon stirring for 10 minutes was 11 μC/g, and the amount of charge of 11 uc/g was maintained even after stirring for 100 hours.

(3) Presence or absence of toner filming The presence or absence of toner filming was investigated by observing the surface condition of the carrier after stirring for 100 hours using a SEM image.

(Results) No toner adhesion was observed on the carrier surface, and no toner filming occurred.

(4) Presence of blocking The prototype capsule toner was left in an environment of 60° C. and 130% by weight for 8 hours, but no blocking occurred between the toners.

Furthermore, n of the amide monomer is 5 and 28, respectively.
Similar satisfactory results were obtained in the case of .

Basis for Comparison 1 Evaluations (1), (2), (3), and (4) of Example 2 were conducted in the same manner only for the core material of the capsule toner of Example 2.

(1) The fixing rate was as good as 95% or more regardless of the thickness of the powder image.

(2) When stirring for 10 minutes, it is 7 μC/g, but when stirring for 1 hour, it becomes 1.8 μC/g, and after 100 hours, it is 1.1
There was almost no charge at μC/g.

(3) Toner was fused to the surface of the carrier after stirring for 100 hours, and significant toner filming was observed.

(4) Although there was almost no blocking, some toners were agglomerated together.

disaster relief The following toner components were mixed in the stated amounts.

Amide monomer: 94 parts by weight Dye Nioil Black BY (manufactured by Orient Chemical Co., Ltd.) 3 parts by weight Carbon black: Black Pe5rls L (manufactured by Capot Co., Ltd.)
3 parts by weight This mixture was melt-kneaded and then pulverized and classified to obtain an insulating toner having an average particle size of 11.

Next, 77 parts by weight of this toner (core material) was added to PMMA.
(Shell material) has an average particle size of 0.15I! m MP-14
51 (Soken Chemical) 23 parts by weight was added to Henschel mixer (FM
PMMA was electrostatically adhered to the toner surface by mixing and stirring using a 10B model (Mitsui Miike Seisakusho Engineering). Next, PMMA was fused onto the toner surface of the mixture by impact encapsulation in a high-speed air stream, resulting in a capsule toner having an average particle size of 11.5 tones.

(1) Fixability test Powder images of the prototype capsule toner with different toner layer thicknesses (15 to 34 mm) were created on plain paper using a mini-developing machine, and these were passed through the pressure fixing section of a pressure fixing tester. A fixed image of the toner was obtained. Note that the linear pressure of the pressure fixing section of this testing machine was 15 kg/cm, and the nip length was 0.6 mm.

Next, an adhesive tape (Scotch Mending Tape, manufactured by Sumitomo 3M) was applied to this fixed image with a constant load (1 kg) and peeled off at a rate of 2.5 cm/s, and the optical density before and after the tape was peeled off was measured. The fixing rate was determined by the ratio and the fixing performance was evaluated.

(Results) Regardless of the thickness of the toner powder image after development, the fixing rate was 80.
% or more, showing good pressure fixing properties.

(2) Change in charge amount with stirring time Prototype capsule toner and resin-coated ferrite carrier (average particle size 10,100 p) were mixed at a toner concentration of 4-t%, and stirred using a ball mill.

The developer was sampled during stirring for 10 minutes, 1 hour, 50 hours, and 100 hours, and the amount of charge at each time was measured.

(Results) The amount of charge upon stirring for 10 minutes was 11 μC/g, and the amount of charge of 11 μC/g was maintained even after stirring for 100 hours.

(3) Presence or absence of toner filming The presence or absence of toner filming was investigated by observing the surface condition of the carrier after stirring for 100 hours using a SEM image.

(Results) No toner fusion was observed on the carrier surface, and no toner filming occurred.

(4) Blocking The prototype capsule toner was left in an environment containing 60"C130% by weight for 8 hours, but no blocking occurred between the toners.

Furthermore, n of the amide monomer is 5 and 28, respectively.
Similar satisfactory results were obtained in the case of .

Northern Comparison 1 The evaluations in (1), (2), (3), and (4) of Example 3 were conducted in the same manner as for only the core material of the capsule toner of Example 3.

(1) The fixing rate was as good as 95% or more regardless of the thickness of the powder image.

(2) When stirring for 10 minutes, it is 6.5 μC/g, but 1
When stirred for hours, it becomes 2.1uC/g, and after 100 hours it becomes 0.
．． There was almost no charge at 8 μC/g.

(3) Toner was fused to the surface of the carrier after stirring for 100 hours, and significant toner filming was observed.

(4) Although there was almost no blocking, some toners were agglomerated together.

〔Effect of the invention〕

According to the present invention, the surface of the core material having excellent pressure fixing properties is uniformly coated with the shell material having excellent charging properties, so that the pressure fixing properties are extremely good and there is no blocking or toner filming. toner is obtained.

Claims (1)

[Claims] 1. Consisting of a soft core material containing a colorant and a binder resin as main components and a film-like hard shell material coated around the core material, in which case the binder resin for the core material is A bifunctional amide monomer represented by the following formula: Y-R-Y (In the above formula, Y may be the same or different, and each represents an amide group-containing component having at least one hydroxyl group as a substituent. , and R represents a saturated or unsaturated linear or branched chain group or a cyclic group bonding the Y component.