JPS62195683A - Toner for electrophotography - Google Patents

Abstract

PURPOSE:To enable uniform dispersion of wax to be added and kneaded to prevent an offsetting characteristic in the production stage of a toner by mixing low mol.wt. wax with a styrene/acrylic resin soln. and subjecting the mixture to solvent removal. CONSTITUTION:The resin prepd. by mixing the low mol.wt. wax with the styrene/acrylic resin soln. and subjecting the mixture to the solvent removal is used as an essential component. The styrene/acrylic resin refers to a resin formed by using a styrene as an essential component and copolymerizing the same with other vinyl monomer (e.g., methyl acrylate, etc.) and is used by dissolving the same into a solvent such as benzene. A polyolefin having a relatively low m.p. and about 1,000-45,000 weight average mol.wt. (e.g., PE, PP, etc.) is used for the low mol.wt. wax. The wax is uniformly dispersed in the resin without phase sepn. of the resin and wax if the low mol.wt. wax is added into the styrene/acrylic resin soln. in the solvent removal stage thereof and therefore, the resin in which the wax is uniformly dispersible is obtd. in the case of adding and kneading the wax to and with the resin afterward even if the amt. of the wax to be added in the solvent removal stage is small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toner for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, and the like.

[Conventional technology and its problems]

Electrophotography generally uses a photoconductive substance to fix an electrical latent image on a photoreceptor by heating, pressurizing, or using solvent vapor to obtain a photographic image. Various methods and devices have been developed for the process of fixing the above-mentioned toner image onto a fixing sheet such as paper, but the most common method at present is the heat-pressing method using a heated roller. . Since the method of fixing with a hot roller performs fixing under heat and pressure, it is quick and has extremely good thermal efficiency, so the fixing efficiency is good.

However, while the above method has good thermal efficiency,
Because the toner comes into contact with the hot alar surface in a molten state,
There is a problem of an offset phenomenon in which the toner adheres to and transfers to the surface of the heated roller and is transferred again to the 5th adhering sheet.

In the conventional technology, in order to solve this problem, (1) the melt viscosity of the toner is increased; A low molecular weight wax is uniformly dispersed in the toner to provide release properties.

There is a method. However, in the method (2), the heat 1 given to the resin decreases due to the increased rotation speed of the hot roll as the machine speeds up.

It has the disadvantage of poor fixing properties due to insufficient melting.

The low molecular weight wax addition method (2) is mainly performed by kneading during toner production. There is a method in which (.) is added during the polymerization of toner resin.

However, the method of kneading low-molecular-weight wax during toner production has the drawback that it is difficult to uniformly disperse the wax in the resin, and therefore a large amount of wax is required to provide mold release properties. Further, when a large amount of wax is added, a wax-rich portion is generated in the toner particles, which affects the amount of charge of the toner and has the disadvantage that one image cannot be sharp.

Next, in the method of adding the wax during the polymerization of the toner resin, the wax participates in the polymerization and affects the molecular structure of the resin.

Alternatively, the wax may graft onto the resin and affect the Tg of the resin. Furthermore.

The disadvantage is that the wax itself decomposes, reducing the effectiveness of the mold release agent.

Therefore, it is necessary to realize a technique for uniformly dispersing the wax without adversely affecting the physical properties of the toner.

[Means for solving problems] In order to achieve these problems, the inventors of the present invention

The present invention was completed based on the discovery that when a low molecular weight wax is mixed into a styrene-acrylic resin solution and the solvent is removed, the wax is uniformly dispersed.

That is, one aspect of the present invention is an electrophotographic toner whose main component is a mixture of a low molecular weight wax in a styrene-acrylic resin solution and the resulting solvent is removed.

The present invention enables uniform dispersion by adding wax during solvent removal, and even when the amount of wax added is small, the wax necessary for preventing offset is added and kneaded during toner production using the resin. uniform dispersion is also possible.

The styrene-acrylic resin of the present invention is one in which styrene is mainly copolymerized with other vinyl monomers and has a bone average molecular weight of usually I x 10' to 5 x 10'.

Examples of other vinyl monomers include methyl acrylate, ethyl acrylate, and propyl acrylate.

Butyl acrylate, octyl acrylate, acrylic acid/
Acrylic acid esters such as chlorhexyl, lauryl acrylate, stearyl acrylate, benzyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, hydroxyethyl acrylate, hydroxybutyl acrylate, methyl methacrylate, ethyl methacrylate , propyl methacrylate, butyl methacrylate.

Octyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, furifuryl methacrylate, tetrahydrofurfuryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate 1 Methacrylic acid esters such as hydroxybutyl methacrylate, vinyltoluene, α-methylstyrene.

Aromatic vinyl monomers such as chlorstyrene, diptyl maleate, dioctyl maleinoate, dibutyl fumarate,
Unsaturated dibasic acid dialkyl esters such as dioctyl fumarate, vinyl esters such as vinyl acetate and vinyl propionate, nitrogen-containing vinyl monomers such as acrylonitrile, methacrylonitrile, methacrylamide, and acrylamide.

Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and cinnamic acid 9, maleic acid, and maleic anhydride.

7-'-/' acids, unsaturated dicarboxylic acids such as itaconic acid, monomethyl maleate, monoethyl maleate, monobutyl maleate, monooctyl maleate, monomethyl fumarate, monoethyl fumarate, motuptyl fumarate, monooctyl fumarate unsaturated dicarboxylic acid monoesters such as

What is the styrene-acrylic resin solution of the present invention?

The above resin is dissolved in the following solvent. The solvents include benzene, doluol, kijiroru, and solvent naphtha No. 1 and No. 2.

No. 3, cyclohexane, hydrocarbon solvents such as Tsurpetz 100 and 150° mineral spirits, methanol, ethanol, 1so-7' alcohol, n-phthyl alcohol, 5eC-butyl alcohol.

Alcohol solvents such as 1so-7' alcohol, amyl alcohol, and cyclohexanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, and ester solvents such as ethyl acetate, n-butyl acetate, and cellotsulfur acetate. Solvents include ether solvents such as methylceronelube, ethylcellosolve, butylcellosolve, and methylcarpitol.

The styrene-acrylic resin solution of the present invention may be obtained by solution polymerization, or may be obtained by dissolving a resin produced by bulk polymerization, suspension polymerization, or mass suspension polymerization in the above-mentioned solvent.

The low molecular weight wax of the present invention refers to a polyolefin having a relatively low melting point and a weight average molecular weight of about 1,000 to 45,000, particularly a weight average molecular weight of about 2,000 to 10,000.
Polyolefins of about 100% are preferred. or.

These polyon fins have a softening point of 100 to 18
0°C, especially 130-160°C is preferred.

Specific examples of such polyolefins include polyethylene, polypropylene, polybutylene, etc. Among these, polypropylene is particularly preferred.

The desolvation of the present invention refers to a process in which the above-mentioned styrene acrylic resin is desolventized at normal pressure or reduced pressure at 120 to 250°C. Especially resin or.

In order to prevent thermal deterioration of the low molecular weight wax and to sufficiently remove the solvent, it is preferable to perform the solvent removal under reduced pressure at 150°C to 220°C.

The amount is 0.1 to 5 parts by weight relative to the desolution of the styrene-acrylic resin solution of the present invention. When wax is added during solvent removal, the wax is evenly dispersed in the resin without phase separation between the resin and wax.

Even if the amount of wax added at the time of solvent removal is small, a resin in which wax is easily dispersed evenly even if wax is added and kneaded later can be obtained.

In particular, since the wax is uniformly dispersed, the amount of wax in the toner composition is less than the amount of conventional wax, and the toner can have sufficient anti-offset properties. The total amount of wax in the toner is not particularly limited, but is usually 1 to 20.
Weight%.

The toner of the present invention has developing properties, transfer properties, cleaning properties,
Properties such as crushability and charging stability are also comparable to conventional products.

In producing the toner, a powder obtained by pulverizing the above styrene-acrylic resin by a conventional method, various coloring agents such as carbon black, and, if necessary, ingredients such as nigrosine for adjusting triboelectric charging properties are used. If the addition of charge control agents such as metal azo dyes and low molecular weight wax during desolvation is insufficient.

Insufficient amount of low molecular weight wax required to prevent offset, and magnetic iron oxide in the case of magnetic toner.

Mix reduced iron powder, etc., mix in a kneader, etc., and then crush.

Classify and produce toner. It is also possible to mix other resin components within a range that does not impede the effects of the present invention. The amount of styrene acrylic resin is 30 in the toner ioo part.
~95 parts.

Since the toner obtained by the present invention has a low molecular weight wax uniformly dispersed, the amount of wax used is small (this can prevent offset, and since the amount used is small, other toner properties can also be improved). .

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. In addition, "part" represents a single electric part.

The molecular weight of styrene-acrylic resin is measured by GPC.
It was done according to the law. The equipment and measurement conditions are as follows.

Detector 5HODBX RI 5g-31 column
A-80MX2 +KF-802 Solvent THF (Futrahi L...177 Run flow rate 1.2 i/min Sample 0.25 THF solution production example 1 51.4 Lof flasks with cooling tube, thermometer, nitrogen introduction tube,
A stirrer was attached, 70 parts of styrene and 30 parts of n-butyl methacrylate were charged, and while nitrogen was being introduced,
Bulk polymerization is carried out at 100°C.

When the polymerization rate reached 80%, add 50 parts of pheasant.

4 parts of styrene and 5 parts of n-butyl methacrylate were put into a flask, stirred uniformly, and then taken out.

150 parts of Kijirole was charged into the same polymerization apparatus as above, and under reflux, a mixture of 150 parts of the above resin-motsumer solution and 10 parts of azobisisobutyronitrile was added dropwise over 4 hours using a continuous dropping apparatus to effect polymerization. As a result, a styrene-acrylic resin solution X having a weight average molecular weight of 2x10 and a Tg of 62°C is obtained.

Next, using the same equipment, 70 parts of styrene, 30 parts of n-butyl methacrylate, and 5 parts of low molecular weight polypropylene wax were charged, and bulk polymerization and solution polymerization were carried out in the same manner as in X to obtain a weight average molecular fJi of 2.2. XIO',
A styrene-acrylic resin solution Y having a Tg of 59°C was obtained.

Next, using the same equipment, bulk polymerization was performed with the same monomer composition, and after adding the same amounts of styrene, n-butyl methacrylate, and kijylol, 5 parts of low molecular weight wax was added to the xylol in the solution polymerization, and hereinafter referred to as X. Solution polymerization was carried out in the same manner to obtain 1 weight average molecule i 2,0xlO' T
g. A styrene-acrylic resin solution Z at 58°C was obtained.

Unless otherwise specified, the styrene-acrylic resin produced by the above method is desolventized at 200° C. and a pressure of 20 Hg to obtain a toner resin.

Comparative Examples 1 to 6 The resin solutions X, Y, and Z produced in Production Example 1 were desolventized under the conditions shown in Table 1, and 100 parts of this resin, adhesive, and low-molecular weight! J
Mix the wax shown in table ■ and heat it in a kneader at 120°C.
After melting and kneading for 30 minutes, the mixture was pulverized to obtain coarse toner particles having a particle size of about 2 mm.

The coarse particles were finely pulverized using a jet pulverizer (manufactured by Nippon Niematic Co., Ltd.), and then classified to obtain toner particles each having a particle size of about 10 μm.

This toner was evaluated using a copying machine. The evaluation results are shown in Table I.

Table 2 shows that in Comparative Examples 1 to 3 using resin solution There was a problem that it was a little slow.

Comparative Examples 4 and 5, in which wax was added during one polymerization, had problems of poor offset properties, blocking, and image quality.

The amount of wax added is determined by the amount of solid content in the resin solution. The number of copies per 100 copies is shown.

The F toner particles 109 were stored in a constant temperature △ room at 50° C. for 124 hours, cooled to room temperature, and blocking was visually determined.

○ No blocking occurs △ Light blocking occurs, but it collapses with a weak force.

× Blocking is occurring.

Number of copies: 8 copies at the 10,000th copy Judgment was made visually.

Examples 1 to 12 To 100 parts of the solid content of resin solution X, low molecular weight polypropylene wax was added in the amount shown in Table 1 and the solvent was removed to obtain a resin for toner.

The toner formulation and evaluation method were the same as in Comparative Example 1. The results are shown in Table H.

From Table ■, 0.01 when wax is added during solvent removal.
Although the offset property is improved compared to Comparative Examples 1 to 3 even when the amount is 0.05 parts or more, it is more desirable to add 0.05 parts or more.

Also, if 6 parts or more is added at the time of solvent removal.

It is desirable that the number of copies is 5 or less, as the quality of the copy image is slightly inferior.

[Example 2] In the same manner as in Example 1, resin solution X was used and the solvent removal temperature was carried out under the conditions shown in Table 1 (■) to obtain a toner resin.

The toner formulation and evaluation method were the same as in Comparative Example 1.

Wahan to Shu 111 and Sai 1.

From Table 2, toner produced using resin that was desolventized at 120 to 250°C had almost satisfactory characteristics;
It is particularly desirable to manufacture using a resin that has been desolventized at 50 to 220°C.

〔Effect of the invention〕

From the above, 1. By using the electrophotographic toner of the present invention, offset resistance at high temperatures can be improved with a smaller amount of low-molecular-weight noble wax used than conventional toners, and other toner physical properties are also comparable to conventional toners. I got something.

Claims (1)

[Claims] An electrophotographic toner whose main component is a styrene-acrylic resin solution mixed with a low molecular weight wax and the solvent removed.