JPS6249362A - Resin for electrophotographic toner - Google Patents

Abstract

PURPOSE:To obtain the title toner having an improved image concentration and an anti-extracting property against a chemicals by incorporating a specific copolymer composed of an aromatic vinyl and a conjugated diene and a specific copolymer composed of the aromatic vinyl and an saturated acid ester to the title resin. CONSTITUTION:The title toner comprises 55-95wt% the copolymer (the resin A) having 2,000-50,000 a number average molecular weight composed of 98-80wt% the aromatic vinyl and 2-20wt% the conjugated diene, and 45-5wt% the copolymer (the resin B) having 100,000-1000,000 the number average molecular weight composed of 100-50wt% the aromatic vinyl and 0-50wt% the unsatd. acid ester. The compounding ratio of the resin A and B is 55-95wt%, preferably 65-90wt% the former and 45-5wt%, preferably 35-10wt% the latter. Thus, the title resin which has a stable quality, and is easy to grind into pieces and has the high image concentration and the excellent anti-extracting property against the chemicals is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is directed to the electrophotography of electrophotography. The present invention relates to a toner for developing a latent image, particularly a resin for a heat-fixing type developing toner.

(Prior Art) Generally, the toner image obtained by developing with this type of toner needs to be fixed on a transfer paper or the like, and the heat fixing method is widely used as the fixing method. In particular, the fixing method using a heating roller fixing device has high thermal efficiency because it is a contact dust fixing method, and can reliably fix the toner image using a relatively low-temperature heat source. It is preferable because there is very little risk of ignition.

However, when a toner image is fixed by bringing a heating element into contact with a heated roller fixing device, a so-called offset phenomenon occurs in which a portion of the toner adheres to the heating element and is transferred to the subsequent image area. This offset phenomenon occurs when the viscoelasticity of the toner melted by heating is inappropriate and is either too large or too small.
Therefore, the temperature range in which the offset phenomenon does not occur depends on the type of resin, which is one of the main components of toner, and the type of toner components.
It depends on the content etc. In particular, it is effective to increase the resin molecule i in order to increase the offset temperature.

On the other hand, the fixing temperature is required to be lower from the viewpoint of energy saving, and it is more effective to lower the molecular weight of the resin to meet this requirement. However, when the molecular weight is lower, the offset phenomenon mentioned earlier occurs. It will happen.

Therefore, the wider the fixable temperature range (the range between the lowest fixable temperature and the temperature at which the offset phenomenon begins), the better.
It is said that it is effective to mix a low molecular weight resin and a high molecular weight resin as proposed in . However, even if a mixture of a styrene-based low-molecular-weight resin having a functional group and a styrene-butadiene-based high-molecular-weight resin as specifically disclosed in this proposal is used, the fixable temperature range is not necessarily wide.・In addition, the styrene-butadiene copolymer resin, which has a low-molecular-weight compound and a high-molecular-weight acid, tends to form gel during polymerization, resulting in unstable quality, and furthermore, the disadvantages of being difficult to crush have not been solved. , · On the other hand, in order to increase the density of the fixed toner image (II), it is important to deposit as much toner on the photoreceptor drum at the time of the phenomenon.

In order to control the amount of toner adhesion, it is necessary to optimize the amount of toner band N, and generally a charge control agent is used. However, even if a charge control agent is used, it is often difficult to control the amount of toner adhesion depending on the combination of the charge control agent and the resin (in particular, there is a long-awaited improvement in image density when positively charged).

Also, if copy paper containing toner is tightly sandwiched inside the desk cloak, the paper may not peel off from the desk mat.This is because desk mats generally contain a binder agent in the vinyl chloride resin. It is made by mixing
This phenomenon is caused by the plasticizing agent melting and fusing the toner fixed on the paper, but the chemical extractability of the toner can be improved by using a resin mixture specifically disclosed in JP-A-54-114245. The reality is that it is difficult to solve the problem.

(Problems to be Solved by the Invention) Therefore, the objects of the present invention are to provide a wide fixable temperature range, stable quality, easy pulverization, high image density, and
Moreover, it is an object of the present invention to provide a resin for electrophotographic toners which has excellent chemical resistance (particularly ablasts) extraction properties.

(Means for Solving the Problems) This object of the present invention is to achieve a number average molecular weight of 2.000 to s.
Copolymer (resin A) of 98 to 80% by weight of aromatic vinyl o, o o o and 2 to 20% by weight of conjugated chef (resin A) 55
~95 tq6. and a number average molecular weight of 100,000 and a copolymer (resin B) of 45 to 5 times.

The slightly aromatic vinyl constituting the copolymer of resin A in the present invention is selected from styrene, vinyltoluene, α-alpha-nalstyrene, etc. (preferably styrene), and the conjugated diene is selected from butadiene, isogrene, 1,3-pentadiene, etc.
butadiene). In addition to the aromatic vinyl and the conjugated diene, this copolymer may contain a monomer component copolymerizable with these in an amount of 30% by weight or less in the copolymer. Examples of such monomers include unsaturated acids such as acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, globil acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and methacrylic acid. propyl,
Butyl methacrylate, methacrylic #! Unsaturated acid esters such as 2-ethyl tones, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate; other unsaturated acid conductors such as acrylonitrile and acrylamide; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, etc. This copolymerization composition is appropriately determined within a range where the glass transition point is 40 to 80°C. When the glass tipping point is less than 40°C, the resins tend to block each other (on the other hand, when it exceeds 80°C, it becomes difficult to crush the toner.

In addition, if the number average molecular weight (Mn) is less than 2,000, the offset phenomenon during fixing will be significant, and if the copolymerization ratio of conjugated diene exceeds 2C1 or Mn exceeds 50,000, the gel will become unstable. This tends to cause the quality to become unstable, and mechanical grinding becomes difficult. Preferable Mn is s
, ooo~40.0 mouths 0. If the copolymerization ratio of the conjugated diene is less than 2%, it will be difficult to control the toner to be positively chargeable, and the toner will easily fuse to the desk mat.

As the aromatic vinyl and unsaturated acid ester constituting the copolymer of resin B in the present invention, the same ones as in resin A can be mentioned. In addition, other copolymerizable monomer components may be contained in the copolymer in an amount of 20 weight or less. Examples include those similar to those in resin A and polyfunctional monomers such as divinylbenzene. The ratio of aromatic vinyl and unsaturated acid ester in resin B is appropriately determined within a range such that the glass transition point of the copolymer is 40 to 80°C, but usually aromatic vinyl 10
0 to 50% by weight, and 0 to 50% by weight of unsaturated acid ester. If the glass transition point of resin B is outside the range of 40 to 80°C, the same problems as resin A will occur. Furthermore, if the Mn of resin B is less than 10Q,000, no offset prevention effect can be obtained. On the other hand, 1. OQ 0
．． If it exceeds 000, mechanical pulverization during toner manufacturing becomes difficult.

The mixing ratio of resin A and resin B is 55 to 95% by weight for the former, preferably 65 to 90% by weight for the former, and 45 to 45% for the latter.

It is necessary to set the amount to 5% by weight, preferably 35 to 10% by weight. If the former amount is less than 55 J, it is difficult to control the toner to be positively chargeable, and the chemical extraction resistance becomes poor. On the other hand, if the former exceeds 95% by weight, the fixable temperature range becomes narrow to 10'Q or less and is not practical. Resin A and resin B may be mixed by any method.

For example, it is melt-kneaded using a roll kneader-1 kneader extruder at a temperature of 130 to 160°C, mixed in a latex state, co-coagulated, and dried, or mixed in a solution state and then steam-solidified after evaporating the solvent. You can gain by doing something.

Conventional additives are used in preparing toners using the resins of the present invention. Any pigment or dye can be used as the coloring agent, but carbon blank is particularly effective. Cyn, cetylpyridium chloride, etc. are used. Furthermore, if wax or polypropylene nato, which are commonly used as an offset preventive agent, are used in combination, it is possible to further widen the fixable temperature range.

Note that toner compositions are generally classified into those that contain magnetic powder as a one-component toner and those that are used as a two-component toner mixed with a carrier, and the resin of the present invention can be used in both. Is possible.

(Examples) Next, the present invention will be specifically explained with reference to Examples. All numbers and parts are based on weight.

Example 1 Resin A and Resin B shown in the table were melted in a predetermined ratio with a roll at 140°C for 10 minutes, and then they were melted so that the carbon blank was 10-1 and the charge control agent nigrosine was 10%. A toner composition was obtained. After cooling,
A toner with an average particle size of 15 microns was obtained by finely pulverizing it with a jet mill and further by air classification. The above toner was mixed with an iron powder carrier to create a developer, and electrostatically applied onto an organic photoreceptor using a normal electrophotographic method. After forming a latent image, it was developed, transferred to plain paper by corona discharge, and thermally fixed using a silicone-Teflon thermal roller, and the following evaluations were performed.

The results are shown in Table 1.

Fixing properties: Set the surface temperature of a heated fixing roller (the image surface is a Teflon rubber roller) to a predetermined temperature, and pass the peta black image transferred onto plain paper. The surface temperature of the roller was changed every 10° C. to determine the phenomenon (offset phenomenon) in which the toner adhering to the roller was retransferred to a white area on the same paper, and the lower limit temperature for this occurrence was defined as TH. On the other hand, the fixability was determined by moving the above-mentioned peta black image back and forth 5 times with a friction element equipped with a sand eraser, and comparing the image density after 9 times with that before friction.
When the temperature is maintained at 0% or more, it is determined that the image is fixed, and the lower limit temperature is defined as Tf. ◇ Image density: An image is obtained by copying an electrophotographic test chart in the same manner as above. The image density is measured using a reflection densitometer that shines light onto the black strip and digitally displays the reflected density.

Adhesion of the toner to the desk mat: Judging by the ease with which the paper peels off from the desk mat after leaving the solid black copy side facing the desk mat for a day and night. From Table 90, the toner according to the present invention has a good adhesion property. It can be seen that all of the properties, image density, and adhesion to the desk mat are good.

Example 2 Using a resin with the same composition as Example 1 of the present invention, 0.3μ
A one-component toner with a particle size of 15 μm was prepared in the same manner as in Example 1 by melt-kneading each component with a roll at 140° C. to obtain a composition of 40% magnetic powder, 5% Nigrosine T, and 58.5% resin. When the evaluation was performed, the fixability Tf was 175.
℃, TH0200℃, image density t3, and good adhesion to the desk mat.

Example 3 Example 1 The same method as in Example 1 was carried out except that the resins shown in Table 2 were used instead of the resins used in the examples of the present invention. The results are shown in Table 2.

Claims (1)

[Claims] 98-80% by weight of aromatic vinyl having a number average molecular weight of 2,000-50,000 and 2-20% by weight of conjugated diene
copolymer of 55 to 95% by weight and a number average molecular weight of 100
,000-1,000,000 aromatic vinyl 10
A resin for electrophotographic toner, comprising 45 to 5% by weight of a copolymer of 0 to 50% by weight and 0 to 50% by weight of an unsaturated acid ester.