JP5251389B2 - Method for producing toner for electrophotography - Google Patents

Description

  The present invention relates to an electrophotographic toner and a manufacturing method thereof, and more particularly, to an electrophotographic toner containing a photochromic compound and a manufacturing method thereof.

  2. Description of the Related Art Conventionally, an electrophotographic toner containing a photochromic material as an additive and capable of forming an image that develops color by irradiation with light is known (see, for example, Patent Document 1). However, this electrophotographic toner simply has a photochromic material mixed with the toner, and there is a problem in the dispersibility and durability of the photochromic material.

Further, a display using marking particles made of a mixture of photochromic materials has been proposed (see, for example, Patent Document 2), and this document also describes the incorporation of a photochromic material into a polymer backbone.
However, in this case, it is considered that the photochromic material is incorporated into the polymer backbone by polymerizing the photochromic material into the polymer by radical polymerization based on the type of polymer described. However, radical polymerization is a reaction that easily destroys the chemical structure, and in particular, photochromic materials generally have a structure that easily causes a chemical reaction, so there is a concern that radical polymerization may destroy some or all of the photochromic material. Is big.

JP 2004-061813 A

JP 2006-023737 A

The present invention is made under such circumstances, by the photochromic material is stably integrated in the binder resin is uniformly dispersed, provides a method of manufacturing electrophotographic toner over indicating it by excellent durability The purpose is to do.

In order to solve the above-mentioned problem, a first aspect of the present invention is to melt and knead a raw material mixture containing a polyester resin and a photochromic compound, thereby causing the photochromic compound and the polyester resin to undergo a dehydration condensation reaction , thereby converting the photochromic compound into the polyester There is provided a method for producing an electrophotographic toner , comprising: a melt-kneading step to be incorporated into a resin; and a step of pulverizing and classifying a kneaded material containing a reaction product of the photochromic compound and a polyester resin .

In the production method of the above electrophotographic toner chromatography, dehydration condensation reaction of the photochromic compound and the polyester resin is a carboxyl group and / or ester groups of the photochromic compound, and those occurring between the hydroxyl groups of the polyester resin I can do it. Moreover, in order to advance a dehydration condensation reaction efficiently, it is preferable to evacuate in the melt-kneading process.

  According to the present invention, there is provided an electrophotographic toner that stably disperses a photochromic material into a binder resin and thereby exhibits excellent durability, and a method for producing the same.

Embodiments of the present invention will be described below.
An electrophotographic toner according to an embodiment of the present invention is formed by kneading, pulverizing, and classifying a raw material mixture including a photochromic compound and a polyester resin, and the photochromic compound and the polyester resin are subjected to a dehydration condensation reaction. And

  In this way, by dehydrating and condensing the photochromic compound to the polyester resin, the photochromic compound is incorporated into the polyester resin without being destroyed by the reaction, and as a result, the durability, color developability and color durability of the toner are improved. Can be made.

  The photochromic compound that can be used in the present embodiment is not particularly limited. Various things can be used.

Among these, spiropyran-based photochromic compounds such as indolinospirobenzopyran, 6′-nitrospirobenzopyran, 6′-hydroxyspirobenzopyran can be preferably used.
The dehydration condensation reaction between the photochromic compound and the polyester resin is usually performed between the carboxyl group and / or ester group of the photochromic compound and the hydroxyl group of the polyester resin.

  However, the functional group of the photochromic compound subjected to the dehydration condensation reaction is not limited to a carboxyl group or an ester group, and other condensable functional groups can be used. As such a functional group, for example, a halogenated alkyl group, a sulfonic acid group, an acid anhydride, an isocyanate, a thioisocyanate, a phosphoric acid group, a phosphorous acid group, and a hypophosphorous acid group can be used.

  Moreover, the functional group of the polyester resin in which the dehydration condensation reaction is performed is not limited to the hydroxyl group, and other condensable functional groups can be used. As such a functional group, for example, a primary amino group, a secondary amino group, a thiol group, an acetal group, an epoxy group, or the like can be used. The functional group of the photochromic compound and the functional group of the resin may be reversed.

  The polyester resin is not only free of hydroxyl groups, but also larger by using a polyester resin containing an alkyl oxide such as ethylene oxide or propylene oxide of bisphenol A for improving fixability and the like. An effect can be obtained.

  Since the photochromic compound is colored or discolored by being irradiated with ultraviolet rays, it is possible to give various effects to the printed matter printed by the printer by using a toner containing the photochromic compound. For example, the present invention can be applied to forgery prevention, copy prevention, printed matter whose printed content disappears with time, printed matter capable of displaying the printed content according to a necessary situation, and the like.

  For example, spiropyran-based photochromic compounds change from colorless to blue color when irradiated with ultraviolet rays, so printing with toner containing spiropyran-based photochromic compounds, and irradiating the printed matter with ultraviolet rays to determine authenticity It can be applied to prevention.

The blending amount of the photochromic compound varies depending on the use of the toner, but it is usually preferably about 0.1 to 5% by mass with respect to the whole toner.
The electrophotographic toner according to one embodiment described above can be obtained by kneading a raw material mixture containing a polyester resin, a photochromic compound, and other additives, cooling the kneaded material, and then pulverizing and classifying it. .

  In such a method for producing an electrophotographic toner, the dehydration condensation reaction between the photochromic compound and the polyester resin occurs in the kneading step. As a result, the photochromic compound is incorporated into the polyester resin by a dehydration condensation reaction in the kneading step, and is uniformly dispersed in the polyester resin.

The raw material mixture can be kneaded with a twin-screw kneader, a pressure kneader, an open roll or the like. The pulverized product can be pulverized by a pulverizer such as a jet mill, and the pulverized product can be classified by an air classifier.
Moreover, as another additive contained in a raw material mixture, a mold release agent and a charge control agent can be mentioned.

  Examples of the release agent include olefinic waxes such as polypropylene wax, polyethylene wax, and Fischer-Tropsch wax, natural waxes such as carnauba wax, rice wax, and scale insect wax, and synthetic ester waxes. In order to improve low-temperature fixability and high-speed printing performance, the release agent has a relatively low melting point of about 60 to 100 ° C., and specifically, carnauba wax and synthetic ester wax are preferred.

  As the charge control agent, for example, as a positive charge control agent, a quaternary ammonium salt, an amino group-containing resin or the like, as a negative charge control agent, a metal complex salt of salicylic acid, a metal complex salt of benzyl acid, a calixarene type There are phenol-based condensates and resins containing carboxyl groups. The blending amount of the charge control agent is preferably 0.1 to 5% by mass with respect to the whole toner.

EXAMPLES Hereinafter, the Example and comparative example of this invention are shown, and this invention is demonstrated more concretely.
Example 1
A photochromic compound having a carboxyl group, represented by the following formula (1), a polyester resin for toner having a hydroxyl group, a charge control agent for toner (LR-147 manufactured by Nippon Carlit Co., Ltd.), a wax for toner (Kato) It was kneaded by heating with a twin-screw extrusion kneader together with Carnauba wax manufactured by Yoko Co., Ltd. In order to efficiently advance the dehydration condensation reaction between the photochromic compound and the polyester resin during the kneading, evacuation was performed during the kneading.

  The obtained kneaded material was pulverized by an airflow pulverizer and classified so that the center particle diameter (volume conversion D50) was 9 μm, and then silica was externally added in a mixer to obtain a toner, whereby sample 1 was obtained. .

実施例２
式（２）により表される、エステル基を有するフォトクロミック化合物を用いたことを除いて、サンプル１と同様の方法によりトナーを作成し、サンプル２を得た。

Example 2
A toner was prepared in the same manner as Sample 1 except that a photochromic compound having an ester group represented by Formula (2) was used, and Sample 2 was obtained.

比較例１
式（３）により表される、ポリエステル樹脂のヒドロキシル基と縮合反応を生ずる官能基を含まないフォトクロミック化合物を用いたことを除いて、サンプル１と同様の方法によりトナーを作成し、サンプル３を得た。

Comparative Example 1
A toner is prepared by the same method as Sample 1 except that a photochromic compound that does not contain a functional group that causes a condensation reaction with the hydroxyl group of the polyester resin represented by Formula (3) is used. It was.

＜トナーの評価＞
以上のようにして作成したサンプル１〜３について、次のようにして評価を行った。
即ち、評価用プリンタとしてカシオ計算機（株）製Ｎ５３００プリンタを用いて実写評価を行い、印刷した後に印字サンプルに水銀ランプにて紫外線を照射することによってフォトクロミックトナーを発色させた。トナーの耐久性、フォトクロミック材料の発色状態、フォトクロミック材料の発色の繰り返し耐久性について、下記の基準で評価した。その結果を下記表に示す。なお、色の繰り返し耐久性は、発色した画像に可視光を照射して消色し、これを５０回繰り返した後の発色状態を観察することにより行った。

<Evaluation of toner>
The samples 1 to 3 prepared as described above were evaluated as follows.
That is, an actual image was evaluated using an N5300 printer manufactured by Casio Computer Co., Ltd. as an evaluation printer. After printing, the photochromic toner was colored by irradiating the print sample with ultraviolet rays using a mercury lamp. The durability of the toner, the coloring state of the photochromic material, and the repeated durability of the coloring of the photochromic material were evaluated according to the following criteria. The results are shown in the table below. The repeated color durability was determined by irradiating a colored image with visible light to erase the color and observing the colored state after repeating this 50 times.

○: Excellent ○ △: Good △: Slightly inferior ×: Inferior

上記表１から、サンプル１はトナーの耐久性、フォトクロミック化合物の発色性、フォトクロミック化合物の発色−消色の繰り返し耐久性、いずれにおいても最も優れていた。サンプル２はトナー耐久性に関してはサンプル１と同等のレベルであり、フォトクロミック化合物の発色性と発色耐久性に関しては良好ではあったが、サンプル１と比較するとやや劣っていた。サンプル３は、トナー耐久性はサンプル１、２、と比較して劣っていた。また、発色状態もサンプル１、２、より発色濃度が出ていなかった。繰り返し耐久性に関しては、サンプル１、２、に比べて明らかに劣っていた。

From Table 1 above, Sample 1 was most excellent in all of toner durability, photochromic compound color development, and photochromic compound color development-decoloration repeated durability. Sample 2 was at the same level as toner 1 in terms of toner durability, and was good in terms of color developability and color durability of the photochromic compound, but was slightly inferior to sample 1. Sample 3 was inferior in toner durability to Samples 1 and 2. In addition, the coloring state was not as high as that of Samples 1 and 2. The repeated durability was clearly inferior to Samples 1 and 2.

  These reasons seem to be that in Samples 1 and 2, the photochromic compound and the binder resin are condensed to improve the dispersibility of the photochromic compound, thereby improving the color developability. In addition, it is considered that the durability of the toner has been improved by eliminating the photochromic compound in the toner. Furthermore, it is considered that the photochromic molecule is chemically bonded to the polyester resin by dehydration condensation, so that the deterioration of the photochromic structure is slowed and the repeated color development durability is improved.

  The sample 2 is slightly inferior in color development state and color development durability to the sample 1 because the ester group of the sample 2 is slightly slower in the condensation reaction than the carboxyl group of the sample 1 and is sufficiently This is probably because the condensation reaction has not progressed.

Claims (3)

By melt-kneading a raw material mixture comprising a polyester resin and a photochromic compound, the melt-kneading step of incorporated the photochromic compound in the polyester resin said photochromic compound and the polyester resin by dehydration condensation reaction and,
A step of pulverizing and classifying a kneaded product containing a reaction product of the photochromic compound and a polyester resin
A method for producing a toner for electrophotography , comprising: 2. The electrophotographic process according to claim 1, wherein the dehydration condensation reaction between the photochromic compound and the polyester resin is a reaction between a carboxyl group and / or an ester group of the photochromic compound and a hydroxyl group of the polyester resin. Toner manufacturing method. 3. The method for producing an electrophotographic toner according to claim 1, wherein vacuum evacuation is performed during the melt-kneading step.