JP2731915B2 - Manufacturing method of resin for toner - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing a resin for toner, and more particularly, to a method for producing a resin for toner having excellent offset resistance and storage stability and excellent fixability. .

[Conventional technology]

Conventionally, many inventions have been made with respect to dry toner resins. However, recently, with respect to copiers and recording apparatuses, due to the increase in processing speed accompanying the increase in processing information,
It is desired to improve the copying speed.

In order to satisfy the demand and also from the viewpoint of energy saving, there is an increasing demand for a toner that can be fixed at a low temperature.

However, in order to significantly improve the low-temperature fixability, it is necessary to produce a polymer having a very low molecular weight. However, a large amount of a polymerization initiator or a chain transfer agent must be used in the suspension polymerization method. In addition, the cost is increased, and the initiator remains in the polymer. As a result, the moisture resistance of the toner is adversely affected, and the offset resistance decreases due to a drastic decrease in the softening temperature and the melt viscosity. there were.

Conventionally, as a method for improving low-temperature fixability while maintaining offset resistance, a method using a resin having a wide molecular weight distribution as a resin for toner has been attempted. For example, there is a method in which a high molecular weight polymer and a low molecular weight polymer are separately produced by a solution polymerization method, then mixed in a solution state, and then the solvent is removed. However, in the solution polymerization method, it is difficult to produce a high molecular weight polymer having a weight average molecular weight of 200,000 or more. There was a problem that was difficult.

In addition, it is difficult to produce a high-molecular-weight polymer having a molecular weight of 200,000 or more even by a suspension polymerization method which is advantageous in cost, and a polymer having a sufficiently wide molecular weight distribution has not been obtained.

Emulsion polymerization is one of the methods to obtain high molecular weight polymer.However, since the emulsifier remains in the resin, the moisture resistance of the toner and the fluidity decrease, and the waste liquid has a high BOD. There were problems such as becoming.

In addition, a dry blending method in which a high molecular weight polymer and a low molecular weight polymer are melt-kneaded by an extruder or the like is also known as a uniform dispersion,
There was a problem in compatibility.

[Problems to be solved by the invention]

An object of the present invention is to provide a method for producing a resin for a toner which is low in cost, is excellent in offset resistance and storage stability, and is excellent in fixability.

[Means for solving the problem]

The present invention relates to a high molecular weight polymer (II) monomer obtained by dissolving a low molecular weight polymer (I) obtained by a solution polymerization method having a weight average molecular weight of 10,000 or less, and a 10-hour half-life temperature of 10 hours.
Production of a resin for a toner characterized by obtaining a high molecular weight polymer (II) by suspension polymerization using a polymerization initiator having three or more tertiary butyl peroxide groups in one molecule at 0 ° C. or lower. In the law.

In the present invention, the monomer used for the polymerization of the low-molecular weight polymer and the high-molecular weight polymer may be the same or different in both the case of solution polymerization and the case of suspension polymerization. Any thing, for example, styrene, α-methylstyrene, o-methyl group as a substituent, m-methyl group,
p-methyl group, p-ethyl group, 2,4-dimethyl group, p-
Styrene derivatives having a butyl group, a p-hexyl group, a p-octyl group, a p-nonyl group, a p-decyl group, a p-methoxy group, a p-phenyl group, etc., general formula: CH ₂ CRCR—COO
In R '(where R represents hydrogen or a methyl group), R' represents a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a t-butyl group. , N-pentyl group, n-hexyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, isononyl group, decyl group, dodecyl group, tridecyl group, stearyl group, docosyl group, cyclohexyl group,
Benzyl, phenyl, methoxyethyl, ethoxyethyl, butoxyethyl, phenoxyethyl and other acrylic esters or methacrylic esters, vinyl acetate and vinyl esters such as vinyl propionate, acrylonitrile, methacrylonitrile And monomers having a polymerizable vinyl group such as acrylic acid or methacrylic acid derivatives. These are used in one kind or in a mixture of two or more kinds. Examples of a mixture of two or more types include a monomer mixture containing styrene and / or a derivative thereof, and an alkyl (meth) acrylate as a main component.

In the present invention, the polymerization initiator used for the solution polymerization is not particularly limited, and a known initiator can be used. For example, di-t-butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, acetyl peroxide, isobutyryl peroxide, octanonyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5 -Trimethylhexyl peroxide, benzoyl peroxide, m-toluoyl peroxide, t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t-butyl peroxyvivalate, t-butyl peroxy neodecano Ethate, cumyl peroxy neodecanoate, t-butyl peroxy 2-ethylhexanoate, t-butyl peroxy 3,5,5-trimethyl hexanoate, t-butyl peroxy laurate, t-butyl peroxy Oxybenzoate, t-butyl peroxyisopropyl Examples thereof include carbonate, azobisisobutyronitrile, and 2,2'-azobis- (2,4-dimethylvaleronitrile).
These are used in one kind or in a mixture of two or more kinds.
Among these, use of octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, and m-toluoyl peroxide is preferable from the viewpoint of maintaining the polymerization activity for the monomer and completing the polymerization in a relatively short time. preferable.

The low molecular weight polymer (I) used in the present invention has a weight average molecular weight of 10,000 or less and is produced by a solution polymerization method.

As a specific method, first, a solvent having a weight ratio of 0.5 to 10 with respect to the polymer (I) monomer is added to a reactor equipped with a thermometer, and then a polymerization initiator and, if necessary, a solvent are added. The polymerization is carried out while dropping the monomer and paying attention to heat generation, and after completion of the dropping, stirring is performed while maintaining the temperature of the reactor for several hours to complete the polymerization. The chain transfer agent can be used according to the purpose, but if it is used too much, it may remain until the next suspension polymerization. Therefore, it is preferable to avoid using it as much as possible.

The solvent to be used includes those used in general solution polymerization, and is not particularly limited, and may be arbitrarily selected according to the purpose. As a specific example, for example,
Examples include toluene, xylene, isopropyl alcohol, butyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate, and ethyl ether cellosolov. Among them, xylene is preferable because it can be polymerized at a relatively high temperature and the solvent can be easily removed.

When producing a polymer (I) having a weight-average molecular weight of 10,000 or less, preferably 7000 or less, it is preferable to carry out solution polymerization at a temperature of 130 ° C or more, without using a polymerization initiator or a chain transfer agent. Surprisingly, the storage stability of the toner is improved.

After the solution polymerization is completed, if necessary, the solvent is removed by heating or reducing the pressure. When the residual solvent becomes about 5% by weight or less, if the pressure is reduced, the pressure is released, and the temperature in the reactor is reduced under the condition that the polymer in the reactor does not solidify. Then, the high molecular weight polymer (II) To prepare a monomer solution for suspension polymerization.

The monomers used in the suspension polymerization may be the same as those used in the solution polymerization as described above, or may be different,
What is necessary is just to select arbitrarily according to the objective.

The amount of the monomer for suspension polymerization is preferably 20 to 70% by weight in the resin obtained in the present invention, and if it is less than 20% by weight, the fixability of the toner tends to be insufficient,
On the other hand, if it exceeds 70% by weight, the viscosity of the monomer solution becomes too high, and the operability tends to be insufficient.

Examples of the method of suspension polymerization include the following methods. First, 1 to 10 times the amount of water and an appropriate amount of a suspension stabilizer and, if necessary, a dispersing aid are added to the monomer solution obtained by dissolving the low molecular weight polymer (I) in the reactor,
The above monomer solution is added with stirring, and then a compound having a 10-hour half-life temperature of 100 ° C. or less and having three or more tertiary butyl peroxide groups in one molecule is added to the reactor as a polymerization initiator. Then, the mixture is heated to a predetermined polymerization temperature to carry out the polymerization.

One of the features of the present invention is that by using this specific polymerization initiator during suspension polymerization, polymerization can be performed in a relatively short time and the molecular weight is high, for example, 35% by weight average molecular weight.
Thus, when the toner is used as a toner, it has good offset resistance and storage stability, and has excellent fixing properties.

If the 10-hour half-life temperature of the polymerization initiator exceeds 100 ° C., polymerization within a practical polymerization time will not be completed, and if the number of tertiary butyl peroxide groups is 2 or less in one molecule, the resistance will be poor. A toner having excellent offset properties cannot be obtained. Specific examples of the initiator include, for example, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane.

Known suspension and dispersion stabilizers are used. Specific examples thereof include polyvinyl alcohol, partially saponified polyvinyl alcohol, a sodium or potassium salt of a homopolymer or copolymer of acrylic acid or methacrylic acid, carboxymethyl cellulose, gelatin, water-soluble resins such as starch, barium sulfate, Examples thereof include hardly water-soluble or insoluble inorganic powders such as calcium sulfate, barium carbonate, calcium carbonate, magnesium carbonate, and calcium phosphate. These suspension dispersion stabilizers are used in an amount necessary to complete the operation without coagulation of the resulting resin particles during polymerization, but generally 0.01 to 5 parts by weight per 100 parts by weight of water, Preferably, 0.05 to 2 parts by weight are used.

If necessary, examples of the dispersing aid include electrolytes such as sodium chloride, potassium chloride, sodium sulfate, and potassium sulfate.

The conditions of the suspension polymerization in the present invention vary depending on the type of the monomer to be polymerized and the type and amount of the polymerization initiator, but generally the temperature is 50 to 130 ° C, preferably 70 to 100 ° C.
The appropriate time is about 1 to 10 hours.

In the present invention, during the suspension polymerization, if necessary, when the reaction rate becomes 20 to 80%, a normal polymerization initiator is added, and the reaction rate is 95% or more while maintaining the temperature of the reactor. The polymerization may be completed by stirring until the reaction is completed. After the polymerization is completed,
Cooling, sufficient washing, dehydration and drying are performed to obtain a resin for toner.

Next, the present invention will be described with reference to examples. In the examples, parts indicate parts by weight.

Various evaluations in the examples were performed by the following methods.

<Softening temperature (Ts)> Using a flow tester CFT-500A manufactured by Shimadzu Corporation, using a nozzle with a diameter of 1 mmφ and a length of 10 mm, a load of 30 kg, a 1 g sample was discharged at a rate of temperature increase of 3 ° C./min, and 0.5 g was discharged. The temperature at the time of outflow was defined as the softening temperature.

<Glass transition temperature (Tg)> A chromatogram was prepared at a heating rate of 10 ° C./min using a differential calorimeter, and the intersection between the baseline of the obtained chart and the endothermic curve near Tg was defined as the glass transition temperature.

<Fixability> When a cellophane tape is applied to the fixed toner image and then peeled, the image density (ID) before and after peeling is reduced.
The temperature of the fixing roller, which becomes 80% at ID 0.6, is defined as the fixing lower limit temperature.

<Offset resistance> The degree of contamination of the fixing roller with toner is visually determined,
Evaluation was made at the lowest temperature at which contamination started.

<Production of low molecular weight polymer (I)> After 100 parts of xylene is added to the reactor, the temperature is raised to about 135 ° C., which is the boiling point of xylene. Then, a mixture of 80 parts of styrene and 20 parts of n-butyl acrylate in which 50 parts of xylene and 6 parts of azobisisobutyronitrile were dissolved was added dropwise at 135 to 145 ° C. over 5 hours to carry out polymerization. Thereafter, the mixture was stirred for about 1 hour while maintaining the temperature of the system, and then heated to 145 to 160 ° C. to remove the solvent. Next, the temperature was lowered to 100 ° C., and 100 parts of styrene was added to obtain a styrene monomer resin solution (R1).

The weight average molecular weight of the polymer obtained by the solution polymerization is 60
00.

A styrene monomer resin solution (R2) was obtained in the same manner as in the above reaction except that the amount of azobisisobutyronitrile was changed from 6 parts to 4 parts in the above reaction. The weight average molecular weight of the obtained polymer was 11,000.

[Example 1] 300 parts of water and 0.3 parts of Gohsenol GH-20 (partially saponified poval manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) as a suspension polymerization dispersant were added to a reactor, and mixed and stirred well. Then, at room temperature, 92 parts of the styrene monomer resin solution (R1) were added with 8 parts of n-butyl acrylate and a 10-hour half-life temperature as a polymerization initiator.
Parkadox 12 at 92 ° C (2,2-
A mixture of 0.054 parts of bis (4,4-di-t-butylperoxycyclohexyl) propane dissolved therein was added to the reactor. Thereafter, the temperature in the reactor was raised to 95 ° C.
Time polymerization was carried out. Next, 1.5 parts of benzoyl peroxide was added, and polymerization was further performed for 4 hours.
After washing and dehydration, a powdery resin 1 was obtained. Of the resin 1
Ts was 120 ° C and Tg was 55 ° C. When the molecular weight was measured by GPC, it had two peaks in a high molecular weight region and a low molecular weight region, and the weight average molecular weights of the respective peaks were 354,000 and 9,700. The molecular weight polymer (I) was 20/80 by weight.

Next, 94 parts of the resin 1, 5 parts of carbon black (# 40, manufactured by Mitsubishi Kasei Kogyo Co., Ltd.) and 1 part of a charge control agent (Pontron S-34, manufactured by Orient Chemical Co., Ltd.) were used using a twin-screw extruder. The mixture was kneaded at 150 ° C. for about 5 minutes, cooled and then finely pulverized by a jet mill to obtain a toner having a particle size of 5 to 15 μm.

Using the toner, a fixing tester in which the fixing unit of a copying machine was modified was used to evaluate the fixing property and the offset resistance at a process speed of 130 mm / sec and a pressure of 40 kg. Table 1 shows the obtained results.

Comparative Example 1 The toner performance was evaluated in the same manner as in Example 1 except that the styrene monomer resin solution (R2) was used instead of the styrene monomer resin solution (R1). Table 1 shows the obtained results.

[Comparative Example 2] A 10-hour half-life temperature of 110 ° C instead of Parkardox 12
Was used in the same manner as in Example 1 except that 0.1 part of Perbutyl TM (tri-t-butyltriperoxy trimellitate manufactured by NOF Corporation) was used. No progress was made, and no toner was obtained.

[Comparative Example 3] Except that 0.1 part of Kayaester HTP having a 10-hour half-life temperature of 83 ° C (di-t-butylperoxyhexahydrotetraphthalate manufactured by Kayaku Nuuri Co.) was used instead of Parkadox 12 in place of 0.1 part. The toner performance was evaluated in the same manner as in Example 1. Table 1 shows the obtained results.

Comparative Example 4 Example 1 was repeated except that 0.1 part of Kayalen D (diethylene glycol bis (t-butylperoxycarbonate) manufactured by Kayaku Nuuri Co., Ltd.) having a 10-hour half-life temperature of 97 ° C. was used instead of Parkadox 12. Similarly, the toner performance was evaluated. Table 1 shows the obtained results.

Comparative Example 5 The toner performance was evaluated in the same manner as in Example 1 except that 0.1 part of benzoyl peroxide (BPO) having a 10-hour half-life temperature of 74 ° C. was used instead of Parkadox 12. Table 1 shows the obtained results.

Example 2 In Example 1, 95 ° C. after addition of Parkadox 12
Example 1 except that the polymerization for 6 hours was changed to 95 ° C. and 8 hours.
The toner performance was evaluated in the same manner as described above. Table 1 shows the obtained results.

[Effects of the Invention] As described in detail above, a specific low molecular weight polymer is produced by solution polymerization, and suspension polymerization is performed by using a specific polymerization initiator in the presence of the polymer, so that low cost and anti-offset properties can be obtained. It is possible to obtain a resin for toner which is excellent in stability and preservability and low-temperature fixability, and its effect is extremely high.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Motoji Inagaki 4-160 Sunadabashi, Higashi-ku, Nagoya-shi, Aichi Examiner at Mitsubishi Rayon Co., Ltd. Susumu Sugihara

Claims (1)

(57) [Claims] 1. A monomer for a high molecular weight polymer (II) in which a low molecular weight polymer (I) obtained by a solution polymerization method having a weight average molecular weight of 10,000 or less is dissolved, and a 10-hour half-life temperature of 10
Production of a resin for a toner characterized by obtaining a high molecular weight polymer (II) by suspension polymerization using a polymerization initiator having three or more tertiary butyl peroxide groups in one molecule at 0 ° C. or lower. Law.