JPS60164753A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To improve sticking to soft PVC and resistance to offset and blocking by incorporating a resin component consisting of 95-50wt% a specific epoxy resin and 5-50wt% specific vinyl polymer having hydroxyl group into a toner. CONSTITUTION:An epoxy resin includes a bisphenol type epoxy resin, hydrogenated bisphenol type epoxy resin and polyglycidyl ester type epoxy resin, of which the bisphenol type epoxy resin is more preferable in terms of various characteristics such as printing quality and thermal property. The softening point of the epoxy resin is 90-180 deg.C and particularly preferably 100-160 deg.C and particularly preferably 100-160 deg.C when measured by ring and ball method. The hydroxyl number of a vinyl polymer having a hydroxyl group is 50-350 (KOHmg/ g), more preferably 80-250 (KOHmg/g). The glass transition point thereof is 15-50 deg.C, more particularly preferably 20-40 deg.C. The vinyl polymer having a hydroxyl group is obtainable by polymn. or copolymn. of a vinyl monomer having a hydroxyl group.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a toner for developing electrostatic images used in fields such as electrophotography and electrostatic recording.

(Prior art and its problems) In electrophotography and electrostatic recording, an electrostatic charge image is formed on a photoreceptor by various means, and then the electrostatic charge image is developed with toner particles. A printed matter is obtained through a process of transferring the image to a transfer material such as or Mylar film, and fixing it with a heated roll, a pressure roll, or flash light from a xenon lamp.

In order to prevent stains and damage and allow long-term use or storage, prints are placed in a paper case made of vinyl chloride polymer (hereinafter referred to as soft PVC) that has been treated with dioctyl phthalate or diptyl phthalate without plasticizing. Often left behind.

Toners for developing electrostatic images used in the fields of electrophotography and electrostatic recording include toners using polystyrene resin (Japanese Patent Publication No. 44-16118), toners using styrene-butyl methacrylate copolymer resin ( Special Public Service 111-1982
43), a toner using a polyester resin obtained by reacting a glycol having a bisphenol skeleton with a polybasic acid (Japanese Patent Publication No. 52-25420), a toner using an epoxy resin (Japanese Patent Publication No. 57-96354) However, as a toner that does not have the above-mentioned serious defect that the printed characters and figures will adhere to the sheet even if it is sandwiched between sheets of soft PVC, resulting in missing prints and becoming unreadable, epoxy Limited to toner using resin. However, when toner using epoxy resin is applied to the hot roll fixing method.

A phenomenon in which part of the toner image on the transfer material is transferred to the roll side during fixing, and after one rotation of the roll, the toner transferred to the roll is transferred again to the transfer material, staining the transfer material.

Problems where so-called offset occurs are rare.

To prevent offset by modifying the toner material, if polystyrene resin, styrene-butyl methacrylate copolymer resin, or polyester resin is used, low molecular weight polypropylene is added during toner production. -3304 Publication 1% Kaisho 57-208
No. 559) is known, but it is not effective when applied to toners using epoxy resins, and no effective means for preventing offset of toners using epoxy resins has been found so far.

Another object of the present invention is to provide a toner for developing electrostatic images that does not adhere to soft vinyl chloride and does not cause offset even when heated roll fixing is performed.

(Structure of the Invention) That is, (4) the present invention has a softening point (R ball method) of 9O-
L180℃ epoxy resin 95-50% by weight and (B
) Weight average molecular weight is 60,000 or more, hydroxyl value 50-3
The present invention relates to a toner for developing electrostatic images containing a resin component consisting of 5-50% by weight of a vinyl polymer having a hydroxyl group and a glass transition point of 15-50°C.

As the epoxy resin of the present invention, bisphenol A
Bisphenol type epoxy resin obtained by reacting % of bisphenol with epichlorohydrin, hydrogenated bisphenol type epoxy resin obtained by reacting hydrogenated bisphenol such as hydrogenated bisphenol A with epichlorohydrin, terephthalic acid diglycidyl ester, isophthalic acid There are polyglycidyl ester type epoxy resins such as diglycidyl ester, hexahydrophthalic acid diglycidyl ester, endomethylene tetrahydrophthalic acid diglycidyl ester, and glycidyl ester ether type epoxy resins such as p-oxybenzoic acid glycidyl ester ether. Bisphenol type epoxy resin is preferred from the viewpoint of printing quality and thermal properties. The softening point of the epoxy resin (3) is 90 to 180°C, particularly preferably 100' to 160°C, as measured by the ring and ball method. At temperatures below 90°C, toner tends to cause blocking (a phenomenon in which toner particles aggregate and form clumps).

On the other hand, if the temperature exceeds 180° C., toner formation (melting and pulverization) becomes difficult and fixing performance deteriorates. In addition, as bisphenol type epoxy resins, EvoMitsuku R304, R307, R309 (the above are Mitsui Petrochemical Epoxy ■ trade names), Epicoat 1004, 1007,
It is commercially available as 1009 (trade name, Shell Chemical Co., Ltd.).

The hydroxyl group-containing vinyl polymer (B) of the present invention preferably has a 9 weight average molecular weight (Mw) of 60,000 or more, particularly 80,000 or more. If it is less than 60,000, the improvement effect of the offset □ decreases. Mw is preferably 1.5 million or less, especially 100 million
It is preferably 10,000 or less. If Mw is too large, fixing performance will be poor.

Note that the weight average molecular weight here is determined by gel permeation chromatography using monodisperse standard polystyrene (for example).

The results were calculated based on a calibration curve obtained using Waters Co., Ltd. Tetrahydrofuran is used as the measurement solvent.

Moreover, the hydroxyl value of the vinyl polymer having a hydroxyl group (B) is 50 to 350 (KOHmg/g).

Preferably it is 80 to *50 (KOHmg/g).

If the hydroxyl number d is less than 150, the adhesion resistance to soft vinyl chloride will be poor, and if it exceeds 350, problems will occur such as increased moisture absorption and decreased toner chargeability.

Moreover, the glass transition point of the vinyl polymer having a hydroxyl group (B) is 15 to 50°C, particularly preferably 20 to 40°C. If the glass transition point is less than 15°C, the blocking resistance of the toner will be poor, and if it exceeds 50°C, the fixing property will be poor. The glass transition point was determined using thermo-mechanical analysis method (penetration mode, load 70 g-f/
cm" at a heating rate of 10° C./min).

The (B) vinyl polymer having a hydroxyl group of the present invention can be obtained by polymerization or copolymerization of a vinyl monomer having a hydroxyl group.

As a vinyl monomer having a hydroxyl group.

2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate.

Halfester compounds of glycidyl methacrylate and methacrylic acid or acrylic acid, halfester compounds of bisphenol-type epoxy resin and methacrylic acid or acrylic acid, 2-hydroxyethyl acrylate, hydroxyglobil acrylate, hydroxybutyl acrylate, glycidyl acrylate and methacrylic acid or acrylic acid nophesters. In addition, high humidity (approximately 60
When chargeability and blocking resistance are required under conditions (1RH or higher), a vinyl monomer having a secondary hydroxyl group, such as 2-hydroxyglobyl methacrylate, 2-hydroacrylate, droxypropyl, etc. It is preferable to use 60 mol or more of the vinyl monomer having the group, particularly preferably 80 mol or more. The vinyl monomer having a hydroxyl group is used so that the resulting polymer has a hydroxyl number of 50 to 350.

Vinyl monomers that can be combined with the hydroxyl group-containing vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, p-butylstyrene, p-
Styrene or its derivatives such as chlorostyrene and divinylbenzene, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate.

Pentyl methacrylate, hexyl methacrylate.

Heptyl methacrylate, octyl methacrylate.

Nonyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, beta methacrylate
-Methacrylic acid or its esters such as hydroxyethyl and glycidyl methacrylate.

Acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate , acrylic acid or its esters such as glycidyl acrylate, vinyl acetate.

Vinyl chloride, acrylonitrile, methacrylotrile.

Examples include butyl vinyl ether. Among them, styrene is a preferable example.

Examples include styrene derivatives, methacrylic esters, acrylic esters, etc. Especially preferred as methacrylic esters and acrylic esters are alkyl esters having an alkyl group having 1 to 5 carbon atoms.

The vinyl monomer can be polymerized by any method such as solution polymerization, bulk polymerization, emulsion polymerization, or suspension polymerization.

1g during polymerization! As the polymerization initiator used.

Acetyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, λ4-dichlorobenzoyl peroxide, diisopropyl perdicarbonate, di-2-ethylhexyl perdicarbonate, acetylcyclohexane sulfonyl peroxide, peracetic acid tert-
Butyl, tert-butyl perisobutyrate, azobisisobutyronitrile.

2.2'-Azohis-44-dimethylvaleronitrile.

Tert-butyl per-2-ethylhexanoate, tert-butyl perbenzoate, etc. are used, and these are preferably used in an amount of 0.61 to 15% by weight based on the total amount of vinyl monomer, and are used dissolved in the vinyl monomer. is preferable.

The hydroxyethyl-containing vinyl polymer (B) of the present invention may be a mixture of polymers or copolymers of the above vinyl monomers so that the hydroxyl value and softening point are within the ranges defined above. Therefore, a mixture of a vinyl polymer having a hydroxyl group and a vinyl polymer having no hydroxyl group may be used.

In the present invention, the ratio of (A) epoxy resin and (B) vinyl polymer having hydroxyl group to be used is as follows.

(A)/(Bl is set to 9515 to 50150.

(A)/(If Bl exceeds 9575, no improvement in offset can be expected, and if it is less than 50150, blocking resistance and fixing properties are poor.

The toner of the present invention may contain two coloring agents, a charge control agent, magnetic powder, and other additives as appropriate.

Colorants are carbon black, iron oxide pigment, phthalocyanine blue, and phthalocyanine clean.

Conventionally known materials such as o-f Mi76G L/-K, Watching Red Barium, and Watching Red Strontium can be used, and are appropriately selected and used in the range of 1 to 60% by weight in the toner.

As the charge control agent, nigrosine dyes, fatty acid-modified nigrosine dyes, metal-containing nigrosine dyes, metal-containing fatty acid-modified nigrosine dyes, chromium complexes of 3,5-di-tert-butylsalicylic acid, and the like can be used.

It is usually used in the toner in an amount of 0 to 20% by weight.

Examples of magnetic powders include fine metal powders such as iron, manganese, nickel, and cobalt, as well as iron and manganese.

There are ferrites such as nickel, cobalt, and zinc, and those having an average particle size of 10 μm or less, particularly FC of 1 μm or less, are preferably used in an amount of KO to 70% by weight in the toner.

Other additives include silica powder, hydrophobic silica powder, polyolefin, paraffin wax, fluorocarbon compounds, and fatty acid esters.

Partially saponified fatty acid esters, fatty acid amides, fatty acid metals, etc. can be used, and these are usually found in toners.

0-10% by weight is used.

These materials are mixed, for example, by the following method to produce a toner for developing electrostatic images.

The weighed materials are premixed using a W cone, a blender, a Henschel mixer, etc., and then kneaded using a pressure kneader, a Banbury mixer 9 hot roll, an extruder, etc. at a temperature at which the resin melts. After cooling, it is coarsely ground using a feather mill, bottle mill, pulverizer, hammer mill, etc., and then finely ground using jet air. Next, it is sieved using an Accucut, Alpine classifier, etc., preferably 5 to
The particle size is adjusted to 30 μm.

(Example) Next, examples of the present invention will be shown.

(1) Production of copolymer Add 20,009 g of water to the reaction vessel. After preparing a homogeneous solution by adding 3G of a suspending agent (polyvinyl alcohol manufactured by Denki Kagaku Kogyo ■, Denka Poval W-24), the temperature was raised to 90°C, and the solution was filtered with the vinyl monomer and polymerization initiator shown in Table 1. Benzoyl oxide and 42'-azobis-2,4-dimethylvaleronitrile were added dropwise over about 2 hours, and the mixture was maintained at the same temperature for 10 hours. The mixture was then cooled, filtered, and thoroughly dried to obtain a copolymer.

Weight average molecular weight (abbreviated as Mw), hydroxyl value (abbreviated as OHV), and glass transition point (abbreviated as Tg) of the copolymer
are listed in Table 1.

Margin below (2) Preparation of toner The materials shown in Table 2 were premixed in a Henschel mixer and then melted and kneaded in a kneader. Next, the cooled mixed material was finely pulverized with a pin mill and a jet mill, and classified into 1 toner particles with an average particle size of 10 to 15 μm. Carrier (Japanese iron powder carrier,
Z-250) 752G was mixed to prepare a developer, and a print was made using a dry electronic copying machine (Sharp 8F-750>1&:. Sandwiched between soft PVC containing % by weight, temperature 30℃,
Adhesion to soft vinyl chloride was examined under the conditions of a load of 5 g-f/cm2° and a test time of 1800 hours. A case in which the printed matter did not adhere to the soft PVC and had no printing defects was rated as ○, and a case in which the printed matter adhered to the soft PVC and a printing defect occurred was rated as ×.

(31-2 offset-resistant dry type electronic copying machine (Sharp ■8F-750) was made,
Using a fixing device that can change the temperature of the upper roll, fixing is performed at a linear speed of 70 mm/sec and an inter-roll pressure of 0.5 edge/f 7 cm, and no offset is rated ○.

The offset was marked as ×.

(3) Weigh out 5 g of -3 anti-blocking toner in a metal petri dish, and put it at a temperature of 50°C9.
The growth of the clumps was examined by allowing them to stand for 18 hours at a humidity of 30 SRH. Those that were comparable to those before the test were rated as ○, and those that formed lumps and did not disintegrate easily were rated as ×.

Table 1 shows the evaluation results of Examples 1 to 8 and Comparative Examples 1 to 5 (Effects of the Invention) As is clear from the above, the toner for developing electrostatic images obtained by the present invention has excellent adhesion resistance to soft PVC. , has offset resistance and blocking resistance.

Agent: Patent Attorney Kunihiko Wakabayashi

Claims (1)

[Claims] 1. (A) 95 to 50% by weight of an epoxy resin with a softening point (ring and ball method) of 90 to 180°C, and (B) a weight average molecular weight of 60,000 or more and a hydroxyl value of 50
-350C and a glass transition point of 15-50C. 2.) The toner for developing electrostatic images according to claim 1, wherein the epoxy resin is a bisphenol type epoxy resin. 3. (The toner for electrostatic image development according to claim 1 or 2, wherein the hydroxyl group of the vinyl polymer having a Bl hydroxyl group is present in the vinyl polymer as a secondary hydroxyl group.