JP2512442B2 - Method for producing toner resin - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a resin for toner used in electrophotography or the like, and more specifically, a so-called dry development method of developing electrostatic images. The present invention relates to a method for producing a toner resin used in the method.

(Prior Art) In a dry development method, toner is usually charged by friction with iron powder or glass beads called a carrier, which is attached to an electrostatic latent image on a photoconductor by an electric attraction, It is transferred onto paper and fixed by a heat roll or the like to form a permanent visible image.

As a fixing method, a heating roller method is often used in which the surface of a heating roller formed of a material having releasability for toner is passed through the toner image surface of a sheet to be fixed while being in pressure contact. ing.

This method has a problem that an offset phenomenon occurs. This is because part of the toner that forms the image during fixing
This is a phenomenon in which the toner is transferred to the surface of the heat roller, and the transferred toner is transferred to the next sheet of paper to be transferred again to stain the image. When a crosslinked polymer having a high gel ratio is used as a resin for toner in order to prevent this offset phenomenon, it is preferable from the viewpoint of offset resistance, but on the other hand, the minimum fixing temperature rises and the fixing temperature width narrows. There was a problem. Therefore, in order to prevent offset development and maintain a wide fixing temperature range, a method is known in which a linear polymer and a crosslinked polymer are blended to obtain a resin for toner (JP-A-59-88748). However, the resin obtained by this method does not always ensure a wide fixing temperature range, and the plasticizer resistance (even if the paper on which the toner is fixed and the plastic sheet containing the plasticizer are brought into contact with each other, the toner is Further improvements have also been demanded in respect of characteristics such as difficulty in transfer) and clear image quality.

(Problems to be Solved by the Invention) In view of the above-mentioned conventional resin for toner, an object of the present invention is to obtain a toner having excellent offset resistance and a wide fixing temperature range (particularly low lower limit temperature). Another object of the present invention is to provide a method for producing a resin for a toner, which is

A further object of the present invention is to provide a method for producing a toner resin, in which a toner having a plasticizer resistance, image quality and the like which are equal to or higher than those of conventional products can be obtained.

(Means for Solving Problems) A method for producing a toner resin of the present invention is a linear polymer comprising a styrene monomer and a copolymer having an acrylic acid or methacrylic acid ester monomer as a constituent unit. It is characterized by polymerizing a mixed solution of (a), a polymerizable monomer (b) and a cross-linking agent (c) to obtain a resin having a gel component, which achieves the above object. It

The linear polymer (a) in the present invention is considered to mainly contribute to the low fixing temperature of the toner, and preferably has a melt viscosity at 160 ° C. of about 1 to 2,000 poise. This is because if the viscosity is too low, the plasticizer resistance and blocking resistance are generally poor, and if the viscosity is too high, the fixing temperature becomes high.

Examples of the monomer constituting the linear polymer (a) include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene and 2,4-dimethylstyrene. , Pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, Styrene-based monomers such as p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene; methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, acrylic acid Isobutyl, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methacrylic acid Methyl acrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, stearyl methacrylate, acrylic acid or alkyl esters of methacrylic acid, and 2-chloroethyl acrylate. Acrylic acid or methacrylic acid ester monomers such as phenyl acrylate, methyl α-chloroacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; methyl maleate, butyl maleate, dimethyl maleate. Double bond-containing dicarboxylic acid esters and substituents such as vinyl chloride, vinyl acetate,
Examples thereof include vinyl ester-based monomers such as vinyl benzoate. These may be used alone or in combination of two or more, but it is particularly preferable to use a styrene-based monomer and an alkyl ester of acrylic acid or methacrylic acid in combination.

In the present invention, a mixed solution of the linear polymer (a), the polymerizable monomer (b) and the cross-linking agent (c) described above is polymerized, but the polymerizable monomer (b) is linear. A monomer that can be used as a constituent unit of the polymer (a) can be used, and it is the same as the monomer that forms the linear polymer (a), or the same when polymerizing two or more kinds of monomers. It is preferable to include one.

As the polymerization method, any conventionally known solution polymerization method, suspension polymerization method, emulsion polymerization method, bulk polymerization method, or the like may be adopted, but the gel size should be reduced by chain transfer of the solvent. The solution polymerization method is advantageous in that the lower limit of the fixing temperature can be easily lowered because it is easy and that the linear polymer (a) and the cross-linked polymer described later can be obtained in a more homogeneous and integrated state. It is preferably used.

To prepare a mixed solution of the linear polymer (a), the polymerizable monomer (b) and the crosslinking agent (c) in the solution polymerization method,
The linear polymer (a) may be added to the solution of the monomer (b) and the cross-linking agent (c), and the monomer is polymerized at a low temperature to interrupt the reaction at the initial stage of the polymerization to remove the cross-linking agent (c). You may add.

The cross-linking agent used in the present invention is mainly a monomer having two or more polymerizable double bonds, for example, divinylbenzene,
1,5-hexadiene-3-yne, hexatriene, divinyl ether, divinyl ketone, divinyl sulfone, N,
N-divinyl aniline, divinyl compounds such as divinyl sulfide, for example acrylic acid phthalate, diallyl compounds such as diallyl carbinol, double bonds such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, etc. A carboxylic acid ester having two or more carboxylic acid esters may be used alone or as a mixture.

The presence of the gel component in the resin obtained by the present invention is because a crosslinked polymer composed of the polymerizable monomer (b) and the crosslinking agent (c) (in some cases, the linear polymer (a)) is produced. It is considered that the ratio (gel fraction) is
The higher the value, the better the offset resistance, plasticizer resistance, blocking resistance, etc., but if it is too high, the lower limit of the fixing temperature rises, and if it is too low, the effect such as offset resistance is not expressed. The amount is not less than wt%, preferably 10 to 60 wt%. The gel fraction is measured as follows. First, the resin of the present invention is placed in a container (W ₁ g) and weighed (W ₂ g). Put a large amount of toluene in the container and leave it for 24 hours. During this period, the container is shaken several times to promote the diffusion of the resin-soluble component into toluene. After that, the mixture is allowed to stand still for 48 hours or more to allow the gel content to settle. The supernatant is removed with a dropper, the gel is dried and weighed (W ₃ g). The gel fraction is Calculated as

The mixing ratio of the linear polymer (a) to the polymerizable monomer (b) and the crosslinking agent (c) is generally 10:90 to 90:10 by weight,
It is preferably used in the range of 30:70 to 60:40.

The resin obtained by the method of the present invention has a structure in which the linear polymer (a) microscopically penetrates into the crosslinked polymer produced by the polymerization of the polymerizable monomer (b) and the crosslinking agent (c) (encapsulation). Therefore, even if the lower limit of the fixing temperature is kept low by using a linear polymer having a low melt viscosity, excellent blocking resistance and plasticizer resistance, Further, since the linear polymer (a) and the crosslinked polymer are integrated, it is considered that a toner having excellent imageability and a wide fixing temperature range can be obtained.

(Example) Example 1 260 g of toluene was put into a 2 l separable flask, the air was replaced with nitrogen gas, and then this system was heated to the boiling point of toluene. A mixture of 83 g of styrene, 17 g of n-butyl acrylate, and 2 g of benzoyl peroxide as a polymerization initiator was dissolved while stirring under reflux of toluene.
Solution polymerization was carried out while dropping for 2.5 hours. (160 ° C
Melt viscosity of 36 poise, weight average molecular weight of 8600, resin a. ) After the completion of dropping, the mixture is aged for 1 hour while stirring at the boiling temperature of toluene. In this system, styrene 73
A mixture of g, 22 g of n-butyl acrylate and 5 g of divinylbenzene is added. Then, 3 g of benzoyl peroxide dissolved in 100 g of toluene is added dropwise over 2 hours to carry out a crosslinking reaction. Then, the temperature of the system was gradually raised to 180 ° C., and toluene was removed under reduced pressure to obtain a resin. This resin is cooled and crushed to form a flaky resin A of the present invention.
I got The gel fraction was 22%.

Resin A100 parts by weight and carbon black (diamond black
SH, Mitsubishi Kasei Co., Ltd.) 5 parts by weight are melt-blended, cooled, coarsely pulverized, and then finely pulverized with a jet mill to obtain about 13-
A toner having an average particle size of 15 microns was made.

4 parts by weight of this toner was mixed with 96 parts by weight of an iron powder carrier having an average particle size of about 50 to 80 microns to prepare a developer, and this developer was used to obtain an object. The used electrophotographic copier is Fuji Xerox 3500.

For the evaluation of plasticizer resistance, 5c of agricultural vinyl chloride sheet containing 30% by weight of dioctyl phthalate as a plasticizer was used.
Cut it into m squares, press it onto a copy with a pressure of 1 kg, and apply it to 60 ° C.
I left it in a constant temperature bath for 24 hours to see if the copy was transferred to a vinyl sheet. In the developer using resin A,
No transcription was observed.

The fixing temperature range was determined by variously changing the set temperature of the heat roller of the electrophotographic copying machine and examining the set temperature for fixing without causing offset. For the developer using resin A, from 160 ℃ to 2
It was found to have a wide fixing temperature range of 40 ° C or higher.

The obtained image had no fog and was excellent in resolution.

Example 2 In the same manner as in Example 1, a linear styrene / n-butyl acrylate (83/17) copolymer (resin b) having a weight average molecular weight of 9,000 was obtained. To this system is added a mixture of 130 g of styrene, 10 g of methyl methacrylate, 50 g of n-butyl acrylate and 10 g of divinylbenzene. Then, 6 g of benzoyl peroxide dissolved in 100 g of toluene is added dropwise over 2 hours to carry out a crosslinking reaction. After that, the system temperature is 180 ℃
While gradually raising the temperature to 1, remove toluene under reduced pressure,
A resin was obtained. The gel content was 42%. This resin was cooled and pulverized to obtain a flake-shaped resin B. A toner and a developer were prepared in the same manner as in Example 1 and their physical properties were evaluated.

As a result of evaluation of plasticizer resistance, no transfer was observed in the developer using the resin B. Regarding the fixing temperature range, it was found that the developer using the resin B has a wide fixing temperature range of 160 ° C. to about 240 ° C. The obtained image had no fog and was excellent in resolution.

Comparative Example 1 64 parts by weight of resin a, styrene-n-butyl acrylate-divinylbenzene cross-linked polymer (gel fraction 60.3%) 36
Parts by weight, and carbon black (the same as in Example 1) 5
Parts by weight were melt blended, cooled, coarsely pulverized, and then finely pulverized by a jet mill to prepare a toner having an average particle size of about 13 to 15 microns. This is a blend of the same gel components as in Example 1.

4 parts by weight of this toner was mixed with 96 parts by weight of an iron powder carrier having an average particle size of about 50 to 80 microns to prepare a developer, and a copy was obtained using this developer.

In the plasticizer resistance test, transfer is slightly observed.

 The fixing temperature range was 170 ° C to 240 ° C.

The obtained image was slightly fogged and the resolution was inferior to that of Example 1.

Comparative Example 2 30 parts by weight of resin b, styrene-n-butyl acrylate-divinylbenzene cross-linked polymer (gel fraction 60.3%) 70
Parts by weight, and carbon black (the same as in Example 1) 5
Parts by weight were melt blended, cooled, coarsely pulverized, and then finely pulverized by a jet mill to prepare a toner having an average particle size of about 13 to 15 microns. This is a blend of the same gel components as in Example 2.

4 parts by weight of this toner was mixed with 96 parts by weight of an iron powder carrier having an average particle size of about 50 to 80 microns to prepare a developer, and a copy was obtained using this developer.

In the plasticizer resistance test, transfer is slightly observed.

 The fixing temperature range was 170 ° C to 230 ° C.

The obtained image was slightly fogged and the resolution was inferior to that of Example 2.

(Effects of the Invention) The method for producing a resin for toner of the present invention is configured as described above, and according to the present invention, the offset temperature resistance is excellent and the fixing temperature range is wide, and the plasticity resistance, blocking resistance, and Thus, a toner resin that gives a toner having good image quality can be obtained.

Claims (4)

(57) [Claims] 1. A linear polymer (a) comprising a copolymer having a styrene monomer and an acrylic acid or methacrylic acid ester monomer as a constitutional unit, a polymerizable monomer (b) and a crosslinking agent ( A method for producing a toner resin, which comprises polymerizing the mixed solution of c) to obtain a resin having a gel content. 2. The method for producing a resin for toner according to claim 1, wherein the gel component is a copolymer having a styrene-based monomer, an acrylic acid or methacrylic acid ester-based monomer, and a crosslinking agent as constitutional units. 3. The method for producing a resin for toner according to claim 1, wherein the linear polymer has a melt viscosity at 160 ° C. of about 1 to 2,000 poise. 4. The method for producing a toner resin according to any one of claims 1 to 3, wherein the gel content is about 5 to 60% by weight.