JPS63109447A - Binder for toner - Google Patents

Abstract

PURPOSE:To obtain excellent low temp. fixability, offset resistance and storage stability by using specific polyester as a chief material. CONSTITUTION:The polyester (X) which is obtd. by subjecting glycol or polyester glycol having a hydroxyl group at the terminal and tetracarboxylic dianhydride to chain extension by selective monoesterification reaction and has >=5 ratio Mw/Mn of the weight average mol.wt. Mw to the number average mol.wt. Mn is used as the chief material. The glycol is exemplified by ethylene glycol, diethylene glycol, etc., and the polyester glycol having the hydroxyl group at the terminal is obtd. by condensing dicarboxylic acid or lower alkyl ester and glycol. The tetracarboxylic dianhydride is exemplified by 1,2,4,5-benzene tetracarboxylic dianhydride, 1,2,3,4-butene tetracarboxylic dianhydride, etc. The selective monoesterification reaction of the polyester glycol having the hydroxyl group at the terminal and the tetracarboxylic dianhydride is executed in the absence or presence of a solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a binder for preparing toner used for developing electrostatic images formed in electrophotography, electrostatic photography, electrostatic recording, etc. It is related to.

2. Description of the Related Art Generally, an electrostatic image is developed into a toner image by using toner, which is a colored powder, and this toner image is fixed as it is or after being transferred to a transfer paper or the like.

Normally, toner is prepared by blending binder components and coloring components with a charge control agent, etc. as necessary, melting and mixing them under heating, and then pulverizing them to a predetermined particle size. However, the performance of toner depends on the binder components. greatly affected.

Although various resins are known as binder components of toners, recently, polyester binders have attracted attention because they have large negative chargeability and excellent low-temperature fixing properties and are suitable for high-speed copying.

Documents using polyester as a toner binder include:
There are some things mentioned below.

■ 1,2.4-benzenetricarboxylic acid - cyclic 1.2
1,4-benzenedicarboxylic acid polymerized with anhydride and 2
, using a polymerized esterification product with 2-dimethyl-1,3-propanediol (Japanese Patent Application Laid-Open No. 1686-1686)
(No. 60), (A) alkyl-substituted dicarboxylic acids and/or alkyl-substituted diols, (B) trivalent or higher polycarboxylic acids and/or trivalent or higher polyols, (C) dicarboxylic acids, (D) ethers Acid value 10-60 obtained from components containing diphenols
(Japanese Unexamined Patent Publication No. 59-7960) using a non-linear, low melting point polyester; ■ an etherified diphenol that has been propoxylated and/or ethoxylated and has a propoxy group content of 50% or more; Acid value 10-100 obtained by reacting the above aromatic carboxylic acids with phthalic acids containing up to 40 mol%
(Japanese Unexamined Patent Publication No. 59-29256).

Problems to be Solved by the Invention As mentioned above, toner using a polyester binder seems to be advantageous in terms of low-temperature fixing properties, but when actually examined, the problem is that it tends to cause an offset phenomenon. face. Offset phenomenon is when some of the toner is transferred to the heated roller, staining the surface of the transfer paper that is subsequently fed, or even when the toner is transferred to the pressure roller that is pressed by the heated roller, causing the surface of the transfer paper to become dirty. Refers to the phenomenon in which the back side becomes dirty.

Although low-temperature fixability and offset prevention properties are originally contradictory physical properties, it is possible to prevent the offset phenomenon while maintaining the low-temperature fixability, which is a characteristic of toners using polyester binders. This is an issue that must be resolved in order to put toner into practical use.

The inventions (1), (2), and (3) introduced in the "Prior Art" section above attempt to address this problem, but they have the following problems.

That is, the toner using the binder (2) above has a minimum melting temperature (fixing start temperature) of approximately 300 to 390'F, or approximately 149 to 196°C (the minimum melting temperature in the example is 168°C), and is capable of low-temperature fixing. It's not always enough in terms of sex.

The toner using the above binder is designed to prevent the fixation point from rising and ensure offset properties by introducing soft segments such as alkyl-substituted dicarboxylic acids and/or alkyl-substituted diols into the polyester skeleton. However, there are problems in terms of resin manufacturing, such as the need for considerable skill when manufacturing polyester in order to balance both properties.Also, other types of resins that have both low-temperature fixing properties and offset resistance Finding a binder is something that this industry strongly desires, as it expands the options.

The toner using the above binder @ attempts to secure high-speed fixing properties and anti-offset properties by using a polyvalent metal compound in combination with the limitations of improving polyester. Because this is done by externally blending compounds, performance may vary due to slight differences in crosstalk conditions.Additionally, the use of metal compounds in combination may change the amount of charge of the toner, and the binder It would be more advantageous to solve the above problem by improving only the polyester as a polyester.

In view of this situation, the present invention has been made to solve the above problems.

Means for Solving the Problems The present invention provides glycol or polyester glycol (a) having a hydroxyl group at the terminal, and tetracarboxylic dianhydride (
b) Polyester (X) obtained by chain extension by selective monoesterification reaction, and having a ratio Mw/Mn of weight average molecular weight Mw to number average molecular weight Mn of 5 or more
``A toner binder comprising as a main ingredient.''

The present invention will be explained in detail below.

The polyester (X) in the present invention is obtained by chain-extending a glycol or a polyester glycol (a) whose terminal is a hydroxyl group and a tetracarboxylic dianhydride (b) through a selective monoesterification reaction.

(Glycol> Glycol here includes ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1゜5-bentanediol , 1.6-hexanediol, 1.7-hebutanediol, 1.8-
Octanediol, 1,9-nonanediol, 1,10
-Decanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-
Propanediol (neopentyl glycol), 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-ynebutyl-1,3-propanediol, 3
-Methyl-1゜5-bentanediol, 2,2.4-)
Dimethyl-1,6-hexanediol, 1,2-cyclohexane dimetatool, 1,3-cyclohexane dimetatool, 1,4-cyclohexane dimetatool, 2,2
, 4.4-tetramethyl-1,3-cyclobutanediol, 4.4'-thiodiphenol, 4.49-methylenediphenol, 4,4'-(2-fulbornylidene)diphenol, 4°4'- Dihydrochylebiphenol, 0
-lm- and p-dihydroxybenzene, 4,4°-
Impropylidenephenol, 4,4'-impropylidenebis(2,6-dichlorophenol), 2,5-naphthalenediol, p-xylene diol, cyclopentane-1,2-diol, cyclohexane-1,2- Examples include diol, cyclohexane-1,4-diol, and the like.

<Polyester Glycol> Polyester glycol having a hydroxyl group at the end can be obtained by condensing a dicarboxylic acid or a lower alkyl ester thereof with a glycol.

As the glycol, the above-mentioned glycols are used here.

Examples of dicarboxylic acids include terephthalic acid, isophthalic acid,
Malonic acid, dimethylmalonic acid, succinic acid, geltaric acid, adipic acid, trimethyladipic acid, pimelic acid, 2
, 2-dimethyl geltaric acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid acid, 1
．． 4-cyclohexanedicarboxylic acid, 2,5-norbornanedicarboxylic acid, 1,4-naphthalic acid, siphenic acid, 4,4°-oxybenzoic acid, diglycolic acid, thiodipropion, 2,5-naphthalene dicarboxylic acid, etc. can give.

These dicarboxylic acids may be acid anhydrides, esters, chlorides, etc., such as dimethyl 1,4-cyclohexanedicarboxylate, dimethyl 2,6-naphthalene dicarboxylate, dimethyl isophthalate, dimethyl terephthalate, terephthalate-diphenyl, etc. etc. can also be suitably used.

In addition to dicarboxylic acids, small amounts of trivalent or higher polyhydric carboxylic acids, such as trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, 4-methylcyclohexene-1,2,3- ) Licarponic acid anhydride, trimesic acid, etc. can also be used in combination.

Polyester glycol is preferable to glycol alone because the characteristic values of the polyester (X) finally obtained can be freely adjusted.

<Tetracarboxylic dianhydride> Tetracarboxylic dianhydride is 1,2゜4.5-
Benzenetetracarboxylic dianhydride (that is, pyromellitic anhydride), 1,2,3.4-butanetetracarboxylic dianhydride, 1,2,3゜4-pentanetetracarboxylic dianhydride, 3゜3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 5-(2,5-dioxotetrahydrofurfuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 5-( 2,5-dioxotetrahydrofurfuryl)-3-cyclohexene-
1,2-dicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, 2,3゜6.7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, Ethylene glycol bistrimelitate dianhydride, 2,2°, 3,3°-diphenyltetracarboxylic dianhydride, thiophene-2,3°4.5
-Tetracarboxylic dianhydride, ethylenetetracarboxylic dianhydride, and the like.

<Selective monoesterification reaction> The selective monoesterification reaction between glycol or polyester glycol (a) having a hydroxyl group at the end and tetracarboxylic dianhydride (b) is carried out in the absence or presence of a solvent. When a solvent is used, the solvent may be benzene, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, or butyl acetate.

Dimethylformamide and the like can be used.

The reaction temperature is 100 to 160°C, which is lower than the usual condensation reaction temperature of 180 to 250°C, in order to proceed with only the selective monoesterification reaction, and the reaction is carried out for about 0.5 to 4 hours. When producing a product with a high molecular weight, after the reaction under the above temperature conditions, the temperature is gradually raised until the final molecular weight is 180~
The temperature should be around 200℃.

<Characteristic values of polyester> The polyester (X) obtained by the above selective monoesterification reaction has various characteristics such as molecular weight, acid value, glass transition temperature, etc., depending on the type and proportion of each ingredient, reaction temperature, reaction time, etc. Although it has various characteristic values, for the purpose of the present invention, first of all, as an essential requirement, it is required that the ratio M%#/Mn of the weight average molecular weight Mw to the number average molecular weight Mn is 5 or more * M If w/Mn is less than 5, the degree of branching and crosslinking density will be low, and the desired low-temperature fixing properties and anti-offset properties cannot be obtained.A particularly preferable range of My/Mn is 10 to 30.

A polyester suitable for the purpose of the present invention must be within a specific Mw/Mn range as described above, but if the following conditions are further satisfied, a more favorable result in terms of physical property balance as a toner binder can be obtained. can get.

■ Number average molecular weight Mn is in the range of 2000 to 30000, ■ Weight average molecular weight Mw is 10000 to 1500000.
■ The acid value is 10mgKOH/g or less, especially 10 to 6
0mgKOH/g; (2) The glass transition temperature is 40°C or higher, especially 55°C or higher.

If the number average molecular weight Mr+ is less than 2,000, the offset resistance will be poor, while if it exceeds 30,000, the low temperature fixing property will be poor.

If the weight average molecular weight Mw is less than 1 oooo, the offset resistance will be poor, while if it exceeds 1,500,000, the low temperature fixing property will be poor.

If the acid value exceeds 100 mgKOH/g, the resulting polyester will have poor water resistance, making it difficult to control charge.

If the glass transition temperature is less than 40° C., blocking may occur, resulting in poor storage stability.

<Preparation of toner> Toner is prepared by blending the polyester (X) and colorant (Y) with additives such as a charge control agent, fluidity improver, release agent, plasticizer, etc. as necessary, and melting the polyester (X) and colorant (Y). This can be achieved by mixing and then pulverizing to a predetermined particle size. In addition,
Other polyester-based or non-polyester-based toner binders can also be used in combination with the above-mentioned polyester (X) within a range that does not impair the spirit of the present invention.

As the colorant (Y), for example, carbon black,
Examples include nigrosine dye, aniline black, calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green offsalate, lamp black, and rose bengal. Among these, carbon black is particularly important.

When obtaining magnetic toner, magnetic materials exhibiting magnetic properties or capable of being magnetized, such as iron, manganese, nickel, cobalt,
Fine metal powder such as chromium, ferrite, permalloy, etc. may be added to the toner.

Function The selective monoesterification reaction between a glycol or a polyester glycol (a) having a hydroxyl group at the terminal and a tetracarboxylic dianhydride (b) is represented by, while a normal condensation reaction is represented by: The former selective monoesterification reaction does not produce water as a by-product, so it can be clearly distinguished from the latter reaction.

obtained by chain extension by the former reaction, and the ratio My/Mn of weight average molecular weight Mw to number average molecular weight Mn is 5
A toner in which the polyester (X) of the present invention as described above is used as the main ingredient of a toner binder, and a colorant (Y) and, if necessary, a charge control agent and other components are blended therein, maintains low-temperature fixability while maintaining low-temperature fixability. It shows the effect of effectively preventing the occurrence of offset phenomenon.

EXAMPLES Next, the toner binder of the present invention will be further explained with reference to Examples. Hereinafter, "parts" and "%" are expressed on a weight basis.

<Manufacture of binder) Example 1 0.5 mol of terephthalic acid, 0.5 mol of isophthalic acid, 0.75 mol of diethylene glycol, and 0.75 mol of neopentyl glycol were added to the entire system together with 0.1% zinc acetate catalyst in nitrogen gas. The mixture was charged into a reactor equipped with an inlet pipe, a thermometer, a stirrer, and a rectification column, and the temperature was raised to 190 to 220"C, and the esterification reaction was carried out for 6 hours while removing the generated water. Thereafter, the mixture was heated to 250"C to carry out the esterification reaction for 6 hours. The condensation reaction was carried out for 1 hour under a reduced pressure of 10 Torr.

As a result, the number average molecular weight is 1700, the weight average molecular weight is 3
600 and a hydroxyl value of 67 gKOH/g was obtained.

Next, 110 g of the polyester glycol obtained above, 100 g of xylene, and 14 g of pyromellitic anhydride (equivalent to the hydroxyl group in the polyester glycol) were charged into the same reactor as above.

After carrying out a selective monoesterification reaction at 140''C for 3 hours, the temperature was raised to 180°C over 2 hours while distilling off xylene, and the temperature was further maintained at the same temperature for 2 hours.

The characteristic values of the obtained polyester were as follows: Number average molecular weight Mn 3500 Weight average molecular weight Mw 78000 My/Mn
22.2 acid value (mgKOH/g)
80 Glass transition temperature ('Q) 64 Example 2 An esterification reaction was carried out with the same charging composition as in Example 1,
Thereafter, a condensation reaction was carried out at 250°C for 2 hours, resulting in a number average molecular weight of 3200, a weight average molecular weight of 6900, and a hydroxyl value of 35.
A polyester glycol of mgKOH/g was obtained.

110 parts of this polyester glycol, 100 parts of xylene
g and 9 g of 5-(2,5-dioxotetrahydrofurfuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride (Epiclon B-4400 manufactured by Dainippon Ink & Chemicals Co., Ltd.) (polyester glycol) (equivalent amount to the hydroxyl group in the
After carrying out the time-selective monoesterification reaction, the temperature was raised to 180° C. over 2 hours while xylene was distilled off, and the temperature was further maintained at the same temperature for 2 hours.

The characteristic values of the obtained polyester were as follows: Number average molecular weight Mn 4700700 Weight average Mw 1010l800/Mn
21.8 acid value (mgKOH/g)
30 Glass transition temperature ("O) 81 Example 3 An esterification reaction was carried out with the same charging composition as in Example 1,
A polyester glycol having a number average molecular weight of 830, a weight average molecular weight of 1570, and a hydroxyl value of 135 mgKOH/g was obtained without performing a condensation reaction.

A selective monoesterification reaction between this polyester glycol and pyromellitic anhydride was carried out under the same conditions as in Example 1 to obtain a polyester.

The characteristic values of the obtained polyester were as follows: Number average molecular weight Mn 3300300 Weight average My 81500 My/Mn
24.7 acid value (mgKOH/g)
120 Glass transition temperature ("0) ff3 Example 4 110 g of polyethylene glycol, 100 g of xylene and 8 g of pyromellitic anhydride were charged into a reactor,
After performing a selective monoesterification reaction at ℃ for 3 hours, the temperature was raised to 180 ℃ over 2 hours while distilling off xylene.
The temperature was further maintained for 2 hours.

The characteristic values of the obtained polyester were as follows: Number average molecular weight Mn 8100 Weight average molecular weight My 155500 Mw/Mn
25.5 acid value (gKOH/g)
28 Glass transition temperature ("Q) 58 Example 5 90.3 mol of terephthal, 0.3 mol of isophthalic, 1.5 mol of diethylene glycol and 0.1 for the total system
% zinc acetate catalyst into the reactor, 190-220
The esterification reaction was carried out for 8 hours while the temperature was raised to 'O' and the generated water was removed, and then the line combination reaction was carried out for 1 hour at 200° C. and under a reduced pressure of 1 OTorr.

As a result, the number average molecular weight was 1440. Weight average molecular weight 2
810. A polyester glycol having a hydroxyl value of 78 mgKOH/g was obtained.

Next, 110 g of the polyester glycol obtained above, 100 g of xylene, and 16 g of pyromellitic anhydride (equivalent to the hydroxyl group in the polyester glycol) were charged into the same reactor as above, and selective monoesterification was carried out at 140°C for 3 hours. After the reaction, the temperature was raised to 180°C over 2 hours while xylene was distilled off, and the temperature was maintained at the same temperature for another 2 hours.

The characteristic values of the obtained polyesteryl were as follows.

Number average molecular weight Mn 5100 Weight average molecular weight M w 108100 Mw/Mu
21.2 acid value (gKQH/g)
85 Glass transition temperature (C) The system was charged into a reactor together with 0.1% dibutyltin oxide, and a condensation reaction was carried out at 220° C. in a nitrogen atmosphere until no water was generated.

The characteristic values of the obtained polyester were as follows. Number average molecular weight Mn θeo.

Multilayer average molecular weight My 1f3500Mu/Mn
2.5 acid value (I1gKOH/
g) 65 glass transition temperature ('O)
63 Comparative Example 2 A selective monoesterification reaction between the polyester glycol obtained in Example 1 and pyromellitic anhydride was carried out at 140°C for 3 hours, and after the temperature was further raised to 180°C, xylene was distilled off in 2 hours, and immediately The reaction was stopped. Other conditions were the same as in Example 1.

The characteristic values of the obtained polyester were as follows.

Number average molecular weight Mn 5500 Weight average molecular weight My 17200 M%#/Mn
3.1 acid value (mgKOH/g)
80 Glass transition temperature ("0) 83 (Toner preparation and evaluation method) L92L11 90 parts of the polyester obtained above, 8 parts of carbon black (carbon black #44 manufactured by Mitsubishi Chemical Corporation) and polypropylene wax (Sanyo Two parts of Viscol 550F (manufactured by Kasei Kogyo Co., Ltd.) were mixed in powder form, and the mixture was supplied to a two-shaft mixer (PCM30, manufactured by Ikegai Iron Works Co., Ltd.) at a temperature of 1.
The powder was kneaded at a 40" C5 rotation speed of 1100 rpm, cooled through a cooling roll, and coarsely ground with a hammer mill to a particle size of 0.8flIII+ or less. 200g/h using LABOJET manufactured by Pneumatic Industries Co., Ltd.
The toner was finely pulverized with r to obtain a toner having an average particle size of 7 to 8 IL.

Firefly if! 5 parts of the toner obtained above and iron powder (TE manufactured by Nippon Iron Powder Co., Ltd.)
95 parts of FV-200/300) were placed in an empty ball mill and stirred, and the charge amount was measured using a blow-off powder charge amount measuring device (Model TB-200 manufactured by Toshiba Chemical Corporation).

5 parts of the toner obtained above and iron powder (EF manufactured by Nippon Iron Powder Co., Ltd.)
Using a mixture of 95 parts of V-150/250), an image was produced using an electronic copying machine equipped with a selenium photosensitive drum, transferred to plain paper, and then transferred to a peripheral speed of 4200 n+m/m using a heated roll coated with fluororesin. The toner was fixed at 11 inches, and the fixing properties of the toner on the paper and the offset properties (adhesion state of the toner on the heat roll) were determined by changing the temperature of the heat roll.

1 Place 20g of the above toner in a sealable glass container,
The sample was left in a constant temperature bath at 0±0.5°C for 7 days, then returned to room temperature, and the presence or absence of fluidity was determined.

<Toner suitability evaluation results> Table 1 shows the toner suitability evaluation results of the toners using the binders of Examples 1 to 5 and Comparative Examples 1 and 2.

From Table 1, it is clear that the toner using the binder of the present invention not only has excellent low-temperature fixability, but also
It can be seen that it has offset resistance over the entire range of , and also has good storage stability.

On the other hand, it can be seen that in the comparative examples in which the Mn/My ratio is smaller than 5, the low-temperature fixing properties and anti-offset properties are poor.

Effects of the Invention A toner using the binder of the present invention not only has excellent low-temperature fixing properties, but also has offset resistance and good storage stability.

It is easy to control the reaction when producing the binder of the present invention, and changes in required properties can also be addressed by changing the degree of chain extension by selective monoesterification reaction.

The fact that the present invention provides a different type of binder from the conventional ones that has both low-temperature fixing properties and anti-offset properties expands the options and thus meets the needs of this industry. .

Claims (1)

[Claims] 1. Obtained by chain-extending a glycol or a polyester glycol (a) having a hydroxyl group at the end and a tetracarboxylic dianhydride (b) through a selective monoesterification reaction, and having a number average molecular weight A toner binder comprising polyester (X) as a main ingredient, the ratio Mw/Mn of weight average molecular weight Mw to Mn being 5 or more. 2. The number average molecular weight Mn of polyester (X) is 2000
~30000, weight average molecular weight Mw is 10000~15
00000, the ratio of weight average molecular weight Mw to number average molecular weight Mn Mw/Mn is 5 or more, acid value is 100 mgKOH
2. The binder for toner according to claim 1, wherein the binder has a glass transition temperature of 40° C. or higher.