JPH0429156A - Positive charge imparting releasing agent - Google Patents

Abstract

PURPOSE:To prevent an offset temp. from increasing, to prevent the flowability of a toner from lowering and to present a stably positive electrostatical chargeability by incorporating an polyolefine resin modified with an organic silane compound having an amino group. CONSTITUTION:This releasing agent incorporates the polyolefine resin modified with the organic silane compound having the amino group. A weight average molecular weight of the polyolefine resin is normally 2000 - 1,000,000 and when the weight average molecular weight is over one million, it is disadvantageous to maintain the proper dispersibility into the resin. The melting viscosity of the releasing agent at 160 deg.C is less than 1000 cps and what the melting viscosity at 160 deg.C is over 1000 cps is insufficient at the offset temp., when it is used as an electrophotographic toner. Thus it shows an uniformly positive electrified tendency and in spite of that the polyolefine releasing agent is introduced a polar group having an electrostatical charge control function, in it the flowability of the toner is not deteriorated and the offset resistance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a positive charge imparting mold release agent. More specifically, the present invention relates to a positively charged electrostatic charge-imparting mold release agent that is suitable for heat-fixing type copying machines or printers and has excellent hot offset properties.

[Prior Art] Conventionally, in electrophotography, electrostatic recording, etc., in order to charge the toner in order to develop an electrostatic image, a negatively or positively charged electrostatic charge imparting agent has been added internally or added to the toner. It is used as an external means.

However, it is known that it is generally difficult to obtain a positively chargeable toner with a stable polarity compared to a negatively chargeable toner.

This is because the binder, which is the main component of toner, generally tends to be negatively charged, but the charge control agent bar is generally difficult to disperse in the toner binder, so the charge control agent in the toner particles is positively charged. It is thought that the concentration of the toner becomes non-uniform, making it difficult to produce a stable positive polarity toner.

Further, in heat-fixing toners, a polyolefin-based release agent is used for the purpose of preventing hot offset onto a hot roll during the fixation process of the toner.

[Problems to be Solved by the Invention] However, this polyolefin mold release agent also generally shows a tendency to be negatively charged.

Furthermore, although this polyolefin mold release agent is not as good as a charge control agent, it is difficult to uniformly disperse it in a toner binder, and charge control agents are generally not compatible with polyolefin mold release agents. bad. Therefore, it is difficult for the polyolefin release agent to be uniformly dispersed in the toner binder, and it is also difficult for the charge control agent to be dispersed, which can cause uneven charging characteristics, especially in positively charged toners, and become an obstacle to obtaining high-quality toners. It has become.

It is desirable to minimize the number of materials whose charging polarity is non-uniform.

A method of imparting a charge adjustment function to a polyolefin mold release agent has been considered, but if a polar group with a charge adjustment function is introduced into a polyolefin mold release agent, a sufficient hot offset temperature, which is originally expected for a mold release agent, may not be achieved. It has not been successful because the toner cannot be obtained or the fluidity of the toner is reduced.

[Means for Solving the Problems] As a result of extensive research into a release agent for electrophotographic toners that does not have a high hot offset temperature, does not reduce toner fluidity, and exhibits stable positive charging characteristics, the present inventors found that: We have arrived at the present invention.

That is, the present invention is a positively charged mold release agent for electrophotographic toner, which is characterized by containing a polyolefin resin modified with an organic silane compound having an amino group.

As the polyolefin resin according to the present invention, ■: polyethylene, polypropylene, ethylene-α-olefin (carbon number 3 to 8) copolymer (e.g., 50% by weight or more of ethylene, especially 70% by weight or more); ■: ■ Maleic acid derivatives (maleic anhydride, maleic acid dimethyl ester, maleic acid di-2-ethylhexyl ester, etc.) adduct; ■: ■ oxide; ■: ethylenically unsaturated carboxylic acid [(meth)acrylic acid, itacon acids, etc. and/or their esters [alkyl (1 to 18 carbon atoms)]
esters, etc.] and ethylenically unsaturated hydrocarbons (ethylene, propylene, butene, etc.), and mixtures thereof.

The weight average molecular weight of this polyolefin resin is usually 20.
000,000 to 1,000,000, preferably 4,000 to 500,000.

If the weight average molecular weight exceeds 1 million, it is disadvantageous in terms of maintaining appropriate dispersibility in the toner resin.

The organic silane compound having an amino group used in the modification according to the present invention includes a silane compound having a group having an olefinically unsaturated bond or a group that can be hydrolyzed when silanized. Examples include compounds represented by the formula (wherein N'RI is an olefinic unsaturated bond-containing group, Xl and X2 are amino group-containing groups, and Yl and Y2 are hydrolyzable organic groups).

In general formula (1) or (2), R1 is vinyl, allyl, butenyl, a group having an ester bond of a terminal unsaturated acid CCH2=C(CHa)Coo(CHi)*
- etc. or, CH2= CR2 In the formula, R2 is H or CH3, U is a hydrocarbon group, n is O
or an integer of 1. Examples of the hydrocarbon group of U include an alkylene group having 1 to 3 carbon atoms.

The amino group-containing groups of Xl and X2 include primary, secondary,
Examples include groups containing a tertiary amino group and a quaternary ammonium group (including amphoteric ones). Specifically, −(Q)
-NH2, the group shown by these is mentioned. R is an alkyl group, benzyl group, etc., Q is an organic group such as an alkylene group having 1 to 4 carbon atoms or a hydroxyalkylene group having 2 to 4 carbon atoms, Z
is the counterion. The counter ion is a halogen ion (
CI, etc.), CHa OS Os, C2H508Oa
Examples include.

Hydrolyzable organic groups for Yl and Y2 include alkoxy groups such as methoxy, ethoxy and butoxy, and acyloxy groups such as acetoxy and propioxy.

Specific examples of silane compounds having an amino group include: - Aminosilanes having a secondary amino group and a styrenic unsaturated group in the molecule (trade name KBM-5 of Shin-Etsu Chemical Co., Ltd.);
76; Examples include silanes.

The content of Si atoms is usually 0.01 to 5% based on the weight of the compound of formula (1). If it is less than 0.01%, it will not exhibit a sufficient hot offset temperature when used as an electrophotographic toner. In addition, the ability to positively charge is also small. If it exceeds 5%, the modified polyolefin resin tends to gel and does not exhibit a sufficient hot offset temperature when used as an electrophotographic toner.

The method of modifying the polyolefin resin according to the present invention with an organic silane compound having an amino group is not particularly limited, but includes A) a method of modifying a low melt viscosity polyolefin resin with an organic silane compound having an amino group. , B
) A method of thermally degrading a high melt viscosity polyolefin resin modified with an organic silane compound having an amino group can be mentioned.

In the method of A) in which a low melt viscosity polyolefin resin is modified with an organic silane compound having an amino group, among the low melt viscosity polyolefin resins listed in the section of the polyolefin resin, ■) is a high melt viscosity polyolefin resin. The resin is heated at a temperature of 300 to 450°C and a reaction time of 0.5 to 1.
It can be obtained by thermal degradation in 0 hours or by single or copolymerization of olefins using known polymerization methods. 2
) can be obtained by addition reacting a polyolefin and a maleic acid derivative in the presence of a peroxide catalyst or in the absence of a catalyst. 3) can be obtained by oxidizing polyolefin with oxygen or oxygen-containing gas (air), or by oxidizing polyolefin with ozone-containing oxygen or ozone-containing gas (air). The acid value of the oxide is usually 50 or less. 4) is an ethylenically unsaturated carboxylic acid and/or alkyl (carbon number 1-18
) Obtained by copolymerization of an ester and an ethylenically unsaturated hydrocarbon. The amount of ethylenically unsaturated carboxylic acid and/or alkyl (C1-C18) ester is usually 30% or less, preferably 10% or less, based on weight.

Examples of a method for modifying a low melt viscosity polyolefin resin with an organic silane compound having an amino group include a method of carrying out an addition reaction in the presence of a peroxide catalyst or in the absence of a catalyst.

The addition reaction is carried out using a peroxide catalyst (benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, t-butyl peroxide) under an inert gas atmosphere. benzoate, 1,1-bis(t-butylperoxy)3,3.5-)limethylcyclohexane, etc.) or in the absence of a catalyst, the reaction temperature is higher than the melting point of the polyolefin resin and lower than 300°C, preferably Examples include a method in which the reaction is carried out at 140 to 200°C for a reaction time of 1 to 20 hours.

The melt viscosity of the mold release agent of the present invention at 160°C is 1000
cps or less, preferably 500 cps or less. 16
If the melt viscosity at 0° C. exceeds 1000 cps, the hot offset temperature will be insufficient when used as an electrophotographic toner. The melt viscosity of the mold release agent at 160° C. can be measured using a Brookfield rotational viscometer. Conditions other than measurement temperature are J Is-1557-1.
970. An oil bath with a temperature regulator can be used to adjust the temperature of the measurement sample.

The charge polarity and charge amount of the mold release agent can be determined using a blow-off charge measuring device (manufactured by Toshiba) or a charge distribution measuring device (manufactured by Micron for wire use).
It can be measured using a conventional method.

The positively charged release agent for electrophotographic toner of the present invention can be made into an electrophotographic toner by containing a binder, a coloring material, and various additives, etc., if necessary.

Examples of the binder include styrene resins, such as copolymers of styrene resins, (meth)acrylic acid ester monomers, and other monomers.

Copolymers can usually be produced by solution polymerization, suspension polymerization or bulk polymerization. Examples of polymerization initiators include azo initiators (azobisisobutyronitrile, azobisisovaleronitrile, etc.), peroxide initiators (same as peroxide catalysts described in the addition reaction section), etc. can be mentioned.

The polymerization reaction is usually carried out in an atmosphere of an inert gas such as nitrogen.

The polymerization temperature is usually 50 to 220°C, preferably 70 to 20°C.
It is 0°C.

The reaction time depends on other conditions, but is usually 1 to 50 hours, preferably 2 to 10 hours. When the reaction time is shorter than 1 hour, it is difficult to control the reaction, and when it exceeds 50 hours, it is economically disadvantageous.

If a solvent is used during polymerization, the solvent is removed after the reaction. Examples of the coloring material include carbon, iron black, benzidine yellow quinacridone, rhodamine B1 phthalocyanine, and the like. As the magnetic powder, powder of a ferromagnetic metal such as iron, cobalt, or nickel, or magnetite, hematite, ferrite, or the like may be used.

Furthermore, various additives include positively charged charge control agents such as glosine and quaternary ammonium salts.

The charge control agent may not be used depending on the purpose, but even if it is used, it can be used in a smaller amount than usual to maintain the desired level of charge.

The components of the electrophotographic toner are usually 0.5 to 30% by weight, preferably 1 to 5% by weight of the release agent having the function of imparting a positive electrostatic charge of the present invention, and usually 45 to 95% by weight of the binder. Preferably 70-90% by weight, usually 3-90% of the coloring material
50% by weight is used.

The release agent of the present invention may be added during toner production or may be mixed in advance with the binder. Furthermore, the system may be added together with other components during binder polymerization.

The production of toner for electrophotography is as follows: 1) After dry blending the toner components, the toner components are melt-kneaded, then coarsely pulverized, finally pulverized using a jet pulverizer, and further classified to obtain particles with a particle size of usually 2 to 20 μm. 2) It can also be obtained by suspension polymerization of the monomer of the binder component in the presence of other toner components to obtain a fine powder with a particle size of usually 2 to 20 μm. is not limited to these.

Toner for electrophotography may contain iron powder, glass beads,
It is mixed with carrier particles such as nickel powder and ferrite and used as a developer for electrical latent images. Furthermore, hydrophobic colloidal silica fine powder can also be used to improve the fluidity of the powder.

Toner for electrophotography is heated and removed by the heat roll section of a copying machine, such as a heat-fixing type copying machine or a printer, and is transferred to a support (paper, polyester film, etc.).
It is used as a recording material.

[Example] The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto.

Example 1 1000 g of high melt viscosity polypropylene was passed through a tubular reactor heated to 380° C. and thermally degraded for 30 minutes to obtain low melt viscosity polypropylene. This low melting polypropylene 1
000 parts were placed in a reactor purged with nitrogen and heated to 160°C, and KBM576 (a silane compound having two secondary amino groups and a styrenic unsaturated group in two molecules manufactured by Shin-Etsu Chemical) 20
1 part and 5 parts of di-t-butyl peroxide were added dropwise over 4 hours, and the reaction was further carried out for 1 hour, and the pressure was reduced. Then, the reaction was carried out at 80°C under pressure using methyl chloride, and the generated HC
I was neutralized to change the secondary amino group to a tertiary amino group to obtain a silane-modified polyolefin resin (mold release agent of the present invention) having a tertiary amino group. This mold release agent had a melt viscosity of 70 cps1 and a durometer hardness of 62 at 160°C.

Example 2 A tertiary amino group was prepared in the same manner as in Example 1, except that the silane compound was X-12-585 (manufactured by Shin-Etsu Chemical, a silane compound having two secondary amino groups and an olefinically unsaturated group in two molecules). A silane-modified polyolefin resin (mold release agent of the present invention) having the following was obtained. The melt viscosity of this mold release agent at 160° C. was 80 c 1) S% durometer hardness was 60.

Comparative Example 1 A high melt viscosity polypropylene resin was thermally degraded at 345 to 350°C for 50 minutes while continuously passing through a tube equipped with a static mixer, and the melt viscosity at 160°C was 150°C.
0 c pSs A modified polyolefin resin (comparative mold release agent) having a durometer hardness of 65 was obtained.

Production Example 1 A binder was obtained by polymerizing 800 parts of styrene and 200 parts of butyl acrylate in a toluene solvent below the boiling point using benzoyl peroxide as a polymerization initiator. The binder has a Tg of 61°C, a number average molecular weight of 6000,
The weight average molecular weight was 110,000. Molecular weight is GP
The test was carried out using method C under the following conditions.

Equipment: HLC802A manufactured by Toyo Soda Measurement temperature = 25°C Sample solution: o, 5 wt% THF solution Solution injection amount 200 μm Detection equipment: Refractive index detector Production example 2 660 parts of styrene and 340 parts of butyl acrylate were used as a solvent, and a polymerization initiator was added. A binder was obtained by carrying out thermal polymerization at 130 to 180° C. without using the binder.

T-g of the binder is 53°C, number average molecular weight is 110
00, and the weight average molecular weight was 70,000.

The molecular weight was measured using the GPC method in the same manner as in Production Example 1.

Usage Example 1 Using the mold release agent from Example 1 and the binder from Production Example 1, a charge measurement sample was prepared by the following method.

Sample Preparation Method Binder: 88 parts Mold release agent of Example 1: 4 parts Carbon black: 8 parts (Mitsubishi Chemical Industries, Ltd.)
MA-100) After powder-blending the above mixture, it was kneaded for 10 minutes at 140° C. and 30 r, p, m in a Laboplasto mill, and the kneaded material was pulverized in a jet mill PJM100 (manufactured by Nippon Unimatic Co., Ltd.). Powder air classifier MSD
(manufactured by Nippon Unimatic Co., Ltd.) to cut fine powder of 2μ or less from the finely ground material.

Next, 1000 parts of an electrophotographic carrier iron powder (F100 manufactured by Nippon Tetsuko Co., Ltd.) was mixed with 25 parts of the above sample to prepare a charge measurement sample.

Comparative Use Example 1 A charge measurement sample was prepared in the same manner as in Use Example 1, except that the release agent in Use Example 1 was the low melt viscosity polypropylene of Example 1 which had an amino group and was not modified with a mechanical silane compound. Created.

(Measurement of charge amount) Electrophotographic carrier iron powder AS was added to 25 parts of these toners.
1000 parts of R-10 (manufactured by Nippon Iron Powder Co., Ltd.) was blended and triboelectrically charged using a tumbler-shaker mixer, and the amount of charge was measured using a blow-off charge measuring device (manufactured by Toshiba Chemical Co., Ltd.). The results are shown in Table 1.

Table 1 (20° C., 65% R, H, - day and night humidity control) Use Example 1 using the mold release agent of the present invention was positively charged, but Comparative Use Example 1 was negatively charged.

Use Example 2 Using the release agent of Example 1 and the binder of Production Example 2, an electrophotographic toner was prepared by the following method, and an electrophotographic developer was also prepared.

Toner making method binder 88 copies Example 1
Mold release agent: 4 parts Carbon black: 8 parts (MA-40 manufactured by Mitsubishi Chemical Industries, Ltd.) Charge control agent: 0. 5 parts (Bontron N-0f manufactured by Orient Co., Ltd.) After powder-blending the above mixture, it was heated at 140°C in a laboplasto mill.
The mixture was kneaded for 10 minutes at 30 r, p, and m, and the kneaded material was pulverized using a jet mill PJM100 (manufactured by Nippon Unimatic Co., Ltd.). Fine powder of 2 μm or less was cut from the finely ground material using a powder air classifier MSD (manufactured by Nippon Unimatic Co., Ltd.).

A toner was obtained by uniformly mixing 3 parts of Aerosil R972 (Nippon Aerosil) with 1000 parts of the obtained powder.

Method for Preparing Developer 25 parts of the above toner was mixed with 1000 parts of carrier iron powder for electrophotography (F-100 manufactured by Nippon Tetsuko Co., Ltd.) to obtain a developer for electrophotography.

Use Example 3 An electrophotographic developer was obtained in the same manner except that the mold release agent of Example 1 was replaced with the mold release agent of Example 2.

Comparative Use Examples 2 to 3 Low melt viscosity polypropylene of Example 1 (melt viscosity 70 c I at 160°C) in which the mold release agent of Example 1 was not modified with the mold release agent of Comparative Example 1 and an organic silane compound, respectively.
Comparative electrophotographic developers (2) to (3) were obtained in the same manner except that the Sl durometer hardness was 55).

Table 2 shows the evaluation results for each developer.

Table-2 Evaluation of developer a: Low melt viscosity polypropylene note) Liquidity Hosokawami Using a Kron powder tester The fluidity index was measured and evaluated.

Hot Offset Resistance Using a commercially available heat fixing type copying machine, evaluation was made based on the temperature of the heat roll at which hot offset occurs.

It was confirmed that the electrophotographic toner containing the release agent of the present invention was excellent not only in toner fluidity but also in hot offset resistance.

Use Example 4 A comparative electrophotographic developer was prepared in the same manner as the toner preparation method of Use Example 2, except that the release agent of Comparative Example 4 was used instead of the release agent of Example 2.

(Measurement of charge distribution) Particle charge distribution measuring device (manufactured by Hosokawa Micron Co., Ltd.)
When the charge amount distribution was measured using FST-1), developer usage example 2 had a sharp charge amount distribution, but developer usage example 4 for comparison had a wide charge amount distribution including reverse charge. Ta.

[Effects of the Invention] When the release agent of the present invention having a function of imparting a positive electrostatic charge is used in an electrophotographic toner containing the release agent, it tends to be positively charged much more uniformly than a normal toner. Even though a polar group having a charge control function is introduced into the polyolefin mold release agent, it not only does not reduce the fluidity of the toner but also provides a toner with excellent offset resistance, making it extremely useful.

Claims (1)

[Scope of Claims] 1. A positively charged release agent for electrophotographic toner, which is characterized by containing a polyolefin resin modified with an organic silane compound having an amino group. 2. S based on the weight of the modified polyolefin resin
The content of i atoms is 0.01 to 5% by weight, and the temperature is 160°C.
Claim 1 wherein the melt viscosity is 1000 cps or less.
The mold release agent described.