JP2003345121A - Toner supply roll - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner supply roll which is excellent in uniformity and is uniform in properties of respective sections. <P>SOLUTION: The toner supply roll for supplying toners (developers) to an image carrying member side is prepared by using a prepolymer which is composed of a polyisocyanate and a polyol and in which the isocyanate group content is 5 to 30%. The polyisocyanate contains at least two kinds selected from the group consisting of 4,4'- or 4,2'- diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, carbodiimide denatured polyisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and tolylene diisocyanate. The polyol is a polyether polyol. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner supply roll, and more particularly, in an image forming apparatus such as a copying machine, an image recording apparatus, a printer or a facsimile, on an image carrier made of an electrophotographic photosensitive member or an electrostatic recording derivative. Such as a photoconductor on which an electrostatic latent image is formed by supplying a predetermined toner (developer) to a developing device used for developing and visualizing the electrostatic latent image formed on the The present invention relates to a composition used for a toner supply roll used for forming a target toner image on the surface of an image carrier.

[0002]

2. Description of the Related Art Conventionally, in image forming apparatuses such as copying machines, image recording apparatuses, printers and facsimiles,
BACKGROUND ART An electrostatic latent image formed on an image carrier made of an electrophotographic photoreceptor or an electrostatic recording derivative is developed by a developing device to be visualized as a toner image. In such a developing device, a toner supply roll made of a soft elastic roll is built in for supplying a predetermined toner (developer) contained in the hopper to the image carrier side.

An elastic roll made of polyurethane foam (sponge) has been used as a toner supply roll in such a developing device. The polyurethane toner supply roll is manufactured, for example, by the following method. First, a molding die for a toner-conveying roll is prepared, and a composition containing polyisocyanate, a polyol, a foam stabilizer, a catalyst, water and the like is mixed by a one-shot manufacturing method and then injected into the molding die. Is foamed in a mold, and then the molded product is released from the mold to manufacture a toner supply roll.

[0004]

The one-shot manufacturing method, which is a general soft polyurethane manufacturing method that has been conventionally used, comprises a polyisocyanate, a polyol, a foam stabilizer, a catalyst,
A raw material such as water is mixed and stirred at once, and then poured into a molding die for a toner supply roll. Since the above one-shot manufacturing method mixes and stirs at once, it is not clear whether sufficient stirring is performed in the polyurethane reaction, and the mixed solution after stirring is sufficiently reacted in the mold for the toner supply roll. It was very unlikely that Therefore, adjustment of the mold temperature and the amount of catalyst was unavoidable, but adjustment of the polyurethane reaction in these was extremely severe and difficult, and it was not always practical. Further, since unreacted materials are mixed and stirred at once, heat generation is extremely large, a large amount of reaction gas is generated, and abnormal bubbles such as air pockets and voids are easily formed. There was a tendency to be inferior to free foaming, such as instability of moldability and variations in physical properties at various parts of the molded product.

Further, in the conventional prepolymer production method using a low molecular weight polyol (chain extender, chain extender), the reaction at the time of mixing and stirring is too slow, and sufficient heat is not generated. Is common in polyurethane elastomer moldings, but not practical in soft (foamed) polyurethanes.

Further, in the case of prepolymerizing a polyisocyanate mixture composed of a plurality of polyisocyanates, it has been general practice to prepolymerize individual polyisocyanates and then mix them.

The present invention has been made in view of the above circumstances, and uses a prepolymer obtained by prepolymerizing a polyisocyanate admixture composed of a plurality of polyisocyanates at one time in order to produce it with high efficiency and stability. An object of the present invention is to provide a toner supply roll configured as described above.

[0008]

To achieve the above object, by using a specific prepolymer, it is possible to improve the moldability and the variation in physical properties, and to manufacture a highly efficient and stable toner supply roll.

That is, the present invention is a toner supply roll used for forming a toner image on the surface of an image carrier in an image forming apparatus, which is composed of polyisocyanate and polyol and has an isocyanate group content of 5 to 3.
A gist of the present invention is a toner supply roll characterized by being constituted by using a prepolymer of 0%.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described.

First, any mold may be used as the molding die for the toner supply roll used in the present invention as long as it has been conventionally used for the toner supply roll.

Next, in the present invention, the prepolymer injected into the mold for the toner supply roll is a prepolymer composed of polyisocyanate and polyol.

As the raw material of the polyisocyanate,
4,4'- or 4,2'-diphenylmethane diisocyanate (pure MDI), polymethylene polyphenyl polyisocyanate (polymeric MDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (water-added MDI) trimethyl hexa Methylene diisocyanate (TMHD
I), toluene diisocyanate (TDI), orthotoluene diisocyanate (TODI), naphthylene diisocyanate (NDI), xylene diisocyanate (XDI), hexamethylene diisocyanate (HMD)
I), paraphenylene diisocyanate (PDI), lysine diisocyanate methyl ester (LDI), dimethyl diisocyanate (DOI) and the like. In order to obtain the above polyisocyanate, it is particularly preferable to use at least two of the above isocyanates and mix them.
Among them, it is preferable to mix and use MDI and TDI.

The above-mentioned polyols include polyethylene adipate (PEA), polybutylene adipate (PBA), polyhexylene adipate (PHA), copolymers of ethylene adipate and butylene adipate, dimer acid type polyols, castor oil type polyols. Polyester polyols such as polycaprolactone polyol, and polyether polyols such as polyoxyalkylene glycol. It is preferable to use these polyols individually or in combination to adjust the molecular weight to 5,000 to 10,000. That is, if it is less than 5,000, the intermolecular distance of the produced prepolymer becomes short, and gelation (thickening) or solidification of the prepolymer due to a decrease in soft segment may occur, resulting in poor storage stability. Further, if it exceeds 10,000, the reactivity of the polyol is lowered, so that the prepolymer production efficiency is lowered. Among the above polyols, the use of polyether polyol is suitable for the production of soft highly elastic polyurethane having excellent resistance to moisture and heat. Further, it is preferable to use a polyether polyol containing at least 5 mol% of ethylene oxide because the moldability is good.

At least a part of the polyether polyol may be replaced with a so-called polymer polyol (trade name: Mitsui Takeda Chemical Co.) modified by polymerizing an ethylenically unsaturated monomer in the polyether polyol. By partly using the above-mentioned polymer polyol, it is possible to improve the air permeability, the hardness and the like without lowering the wet heat durability of the foam. The ethylenically unsaturated monomer is not particularly limited, but includes acrylonitrile, styrene, methyl methacrylate, vinylidene chloride, etc., and these polymers are usually dispersed in the form of fine particles having a diameter of 0.1 to 10 μm.

As the foam stabilizer used together with the above polyisocyanate and polyol, there are used water-soluble polyether siloxane derived from polydimethylsiloxane and an EO / PO copolymer, sodium salt of sulfonated ricinoleic acid and polysiloxane. Examples thereof include a mixture with a polyoxyalkylene copolymer. Among these, water-soluble polyether siloxane is suitable as the polyether polyol-based foam stabilizer.

Hot-molded foams tend to have lower air permeability because they gel faster than slab foams and are overpacked in the mold. For this reason, a foam stabilizer which is basically similar to that for slabs but has a slightly weaker foam stabilizing power and higher air permeability is selected.

Further, since a highly elastic foam has a high system viscosity and a high reactivity, when a usual foam stabilizer for flexible foam is used, the foam is excessively stabilized and the degree of communication is lowered. This causes foam shrinkage. For this purpose, low molecular weight copolymers are used. In some cases, an organic functional group may be used instead of the polyether chain.

As the blowing agent used together with the above polyisocyanate and polyol, water, trichloromonofluoromethane, dichlorodifluoromethane, methylene chloride, trichlorofluoromethane, carbon dioxide, etc. may be used alone or in a mixture. From the viewpoint of protection, it is preferable to use water alone. The amount of foaming agent used is
It is 1.0 to 5.0 parts by mass with respect to 100 parts by mass of the polyol used.

The structure of the cross-linking agent used if necessary is not particularly limited, but may be alkylene glycol, 1,4
Diols such as butanediol (1,4BD), triols such as glycerin and trimethylolpropane (TMP), tetraols such as pentaerythritol, diamines such as ethylenediamine (EDA), diethanolamine (DEA), Triethanolamine (TEA)
These amino alcohols and the like can be used alone or in combination. The amount used is 100 polyols used.
It is 0.1 to 10 parts by mass with respect to parts by mass. Other additives such as flame retardants, colorants, antioxidants, antioxidants and the like can be used as required.

From the viewpoint of easiness of mixing operation and characteristics of the obtained toner supply roll, a suitable combination of the above polyisocyanate, polyol and foam stabilizer is a mixture of MDI and TDI as polyisocyanate. Used as the polyol, polyether polyol,
A combination using a water-soluble polyether siloxane as the foam stabilizer.

Further, a toner supply roll is manufactured by using a prepolymer prepared by polymerizing a polyol in advance with a part of the isocyanate groups in the polyisocyanate. The prepolymer is preferably used by adjusting the isocyanate group content to 5 to 30%. That is, when it is less than 5%, sufficient heat generation cannot be obtained when reacting with a polyol, a foam stabilizer, a catalyst, water, etc., and the reactivity decreases,
It tends to have high specific gravity and high hardness. Also, 30
%, The reaction heat is not so different from the one-shot manufacturing method using polyisocyanate (non-prepolymerization).
It is easily affected by mold temperature and outside temperature, and abnormal bubbles such as voids and air pockets are likely to occur. At the same time, the physical properties of each part of the obtained molded product are not uniform.

The polyurethane molded product obtained by using the above prepolymer is a toner supply roll having a diameter of 30 mm or less and formed in an axial width of 100 to 350 mm, and has a hardness of 40 to 400 g. It is preferably adjusted. That is, the obtained toner supply roll exhibits a particularly excellent toner supply effect within the above hardness. 2A and 2B, the hardness referred to herein means that the toner supply roll is supported by the cored bar portions at both ends thereof, and the polyurethane foam layer has a width of 50 mm (thickness: It is expressed by the load (g) at the time of displacement (compression) of 1 mm when pressed at a speed of 10 mm / min with a jig having a plate-shaped pressing surface of 10 mm), and the larger the value, Shows that the polyurethane foam layer has a high hardness, that is, is hard. In addition, the measurement is performed at three locations in the axial direction as shown in FIG. 2C, and at four locations at every 90 degrees in the circumferential direction as shown in FIG. calculate.

In order to achieve the above hardness, N
It is preferable to set the CO index to 60 to 105. That is, when it is less than 60, not only the polyurethane skeleton is not sufficiently formed, breakage easily occurs at the time of demolding, but also the hardness of the toner supply roll is lowered, and a sufficient toner supply effect cannot be obtained. On the other hand, when it exceeds 105, the hardness of the toner supply roll becomes high, and a sufficient toner supply effect cannot be obtained.

The polyurethane molded article preferably has a wet heat permanent strain rate of 15% or less. That is,
This is because the obtained toner supply roll exhibits particularly excellent wet heat durability within the above range. It is to be noted that the wet heat permanent strain referred to here means that the toner supply roll is supported by the cored bar portions at both ends of the toner supply roll, as shown in FIGS.
The figure shows the degree of restoration after 30 minutes have elapsed after leaving the sleeve for 72 hours at a temperature of 50 ° C. and a humidity of 95% for 72 hours with the sleeve of 1.5 mm displaced (compressed).

JIS K 6202: C _S = (t ₀ -t ₁ ).
/1.5×100 C _S : compression set (%) t ₀ : radius of the first molded product (mm) t ₁ : radius of the molded product after the test (mm) Further, the measurement points are shown in FIG. As shown in c), there are three locations in the axial direction.

That is, the toner supply roll constituted by using the above-mentioned prepolymer not only has a high reaction in the in-mold foaming which is a slow reaction, even when a high molecular weight polyol of 5000 or more is used, but also has a polyurethane in advance. As the resin is being advanced, it has excellent uniformity of polyurethane reaction. The physical properties of each part of the obtained molded product are likely to be uniform.

In the present invention, the toner supply roll is manufactured, for example, as follows, using the above materials and the toner supply roll forming mold. That is, first, according to the conventional method, a bar-shaped core metal is placed in a predetermined toner supply roll forming die. On the other hand, a polyurethane molding composition is prepared by mixing a prepolymer, a polyol, a foam stabilizer, a catalyst, water and the like. At this time, the polyol, foam stabilizer, catalyst, water and the like may be premixed polyol in advance. Then, the composition is poured into the mold and the mold is heated to a temperature of 25 to 80 ° C. to cause a foaming reaction. In some cases, the reaction may be promoted in a heating furnace having a temperature of 50 to 250 ° C. Then, the toner supply roll can be obtained by taking out the molded product from the molding die.

The above-mentioned prepolymer manufacturing method is less susceptible to the influence of the mold temperature and the outside temperature, the polyurethane reaction is uniform, and the physical properties of each part of the molded product are also uniform. Further, since it is possible to suppress heat generation during mixing and stirring, it is possible to prevent abnormal foaming such as voids and air pockets that are likely to occur during molding.

[0030]

EXAMPLES Next, examples will be described together with comparative examples.

Examples 1 to 10 and Comparative Examples 1 to 4 First, a polyol component (polyol, foam stabilizer, catalyst, water, etc.) and polyisocyanate (prepolymer) having the compositions shown in Tables 1 and 2 were added at a liquid temperature of 25 ° C. Adjusted to. Then, both liquids were blended so as to have respective NCO indexes, stirred for 5 seconds with a stirring blade, and then poured into a toner supply roll molding die whose temperature was adjusted to 40 ° C. to manufacture a toner supply roll, and moldability was obtained. , Various physical properties were evaluated. Figure 2 shows the physical properties.
As shown in (c), the roller was divided into A, B, and C, and the physical properties were measured.

[0032]

[Table 1] 1) NCO% of polyisocyanate after synthesis or
Measured (actually measured) value 2) Prepolymer of polyisocyanate (NCO% = 45) manufactured by Nippon Polyurethane Industry Co., Ltd. and polyol (OH value = 24) manufactured by Sanyo Chemical Industry 3) Manufactured by Nippon Polyurethane Industry Co., Ltd. Prepolymer 4 of polyisocyanate (NCO% = 36) and polyol (OH value = 24) manufactured by Sanyo Kasei Co., Ltd. 4) Polyether polyol manufactured by Sanyo Chemical Co., Ltd., O
H value = 245) Mitsui Takeda Chemical Co., Ltd. polymer polyol, O
H value = 286 6) Silicone foam stabilizer made by Nippon Unica Co., Ltd. 7) Tertiary amine catalyst manufactured by Tosoh Corporation 8) Tertiary amine catalyst manufactured by Sankyo Air Products Co., Ltd. 9) (Actual addition amount of polyisocyanate) / Polyisocyanate theoretical reaction amount) × 100 10) Air trap generated during molding 11) Coarse cell coarsening generated during molding 12) Hold the core of the molded toner supply roll,
A 0 mm dedicated measuring jig is lowered at a speed of 10 mm / min to contact the outer peripheral portion of the polyurethane molded product, and load 3 g.
Is set to 0, and the load at a position further compressed by 1 mm 13) The molded toner supply roll is supported by the cored bar portions at both ends thereof, and the polyurethane foam layer has φ
The 16 sleeves were displaced (compressed) by 1.5 mm, left at 50 ° C and 95% for 72 hours, and the degree of restoration after 30 minutes had elapsed after taking out and releasing (JIS K
6202: C _S = (t ₀ −t ₁ ) /1.5×100, C
_S : compressive residual strain rate (%), t ₀ : radius of the first molded product (m
m), t ₁ : radius of the molded product after the test (mm))

[0033]

[Table 2] 14) Polyisocyanate manufactured by Nippon Polyurethane Industry Co., Ltd., NCO% = 45 15) Polyisocyanate manufactured by Nippon Polyurethane Industry Co., Ltd., NCO% = 36 16) TDI, NCO% manufactured by Nippon Polyurethane Industry Co., Ltd.
= 48 17) Crude MDI manufactured by Sumitomo Bayer Urethane Co., Ltd.,
NCO% = 31

[0034]

As described above, according to the present invention, when the toner supply roll is manufactured, the content of the isocyanate group is 5 to 3.
When it is set to 0%, a particularly excellent effect of improving manufacturing efficiency can be obtained. If you use a prepolymer whose polyurethane resin has advanced in advance, it is less likely to be affected by mold temperature and outside temperature,
Excellent polyurethane reaction uniformity. Therefore, it is possible to prevent abnormal foaming such as voids and air pools, and to achieve stable production. Further, the obtained molded product has excellent uniformity and the physical properties of each part are also uniform.

The above-mentioned prepolymer is a composition obtained by previously polymerizing a part of polyisocyanate groups with a polyol. By using the above prepolymer, it is possible to improve the reactivity of the high molecular weight polyol and polyisocyanate, which are slow reacting. Therefore, the molecular weight of 50, which was difficult with the conventional technology,
In-mold foaming using a high molecular weight polyol of 00 to 10,000 was made possible.

Further, the present invention is not a conventional method for producing a prepolymer (full prepolymer) by only reacting a low molecular weight polyol (chain extender, chain extender), but is used for prepolymer synthesis out of the total amount of polyol. It is a semi-one-shot (semi-prepolymer) manufacturing method using a polyol, a catalyst, water, and the like that have not been processed. Since the production of the flexible polyurethane in the present invention also requires heat generation, the above prepolymer (full prepolymer) production method by the reaction of only the low molecular weight polyol is not suitable.

Up to now, the prepolymerization of polyisocyanate is generally carried out in a single system. When a prepolymer composed of at least two kinds of polyisocyanates is prepared, individual polyisocyanates are preliminarily mixed with each other. After being made into a mixture, a manufacturing method of mixing them in a predetermined ratio was performed. In the present invention, a mixture of at least two kinds of polyisocyanates is reacted with a polyol to produce a prepolymer, which can also be expected to significantly improve the production efficiency.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a toner supply roll.

2A and 2B are explanatory views showing a method for measuring the hardness of a polyurethane foam layer of a toner supply roll, wherein FIG. 2A is a plan explanatory view, FIG. 2B is a side explanatory view, and FIG. 2C is an axial measurement point. FIG.

FIG. 3 is an explanatory view showing a method for measuring a wet heat permanent strain rate of a polyurethane foam layer of a toner supply roll,
Is a plan view, (b) is a side view, and (c) is an explanatory view of axial measurement points.

[Explanation of symbols]

1. Skin layer 2. Core metal 3. Polyurethane foam layer 4. Sleeve (φ16mm)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) C08G 101: 00) (72) Inventor Mie Takahashi 1888-2 Kukizaki Kasei Co., Ltd. Inner F term (reference) 2H077 AC04 AD05 FA13 FA22 3J103 AA02 AA13 BA41 FA18 GA02 GA57 GA58 GA60 HA03 HA48 4J034 BA03 DF01 DF12 DF15 DF16 DF20 DG02 HA01 HA07 HC03 HC12 HC13 HC16 HC05 HC73 NA03 HC01 HC73 HC03 HC01 HC73 HC01 HC07 QA01 QC01 QD03 RA19

Claims (10)

[Claims] 1. A toner supply roll used for forming a toner image on the surface of an image carrier in an image forming apparatus, comprising a polyisocyanate and a polyol.
A toner supply roll characterized by comprising a prepolymer having an isocyanate group content of 5 to 30%. 2. The polyisocyanate is 4,4′-
Or 4,2′-diphenylmethane diisocyanate,
2. A mixture of at least two selected from the group consisting of polymethylene polyphenyl polyisocyanate, carbodiimide modified polyisocyanate, 4,4′-dicyclohexylmethane diisocyanate and tolylene diisocyanate. Toner supply roll. 3. The toner supply roll according to claim 1, wherein the polyisocyanate contains 25 to 50% of isocyanate groups. 4. The polyisocyanate is a polyisocyanate having at least 2 functional groups.
The toner supply roll according to any one of 1. 5. The toner supply roll according to claim 1, wherein the polyol is a polyether polyol. 6. The molecular weight of the polyol is 5000 to 1
The toner supply roll according to claim 1 or 5, which is 0000. 7. The toner supply roll according to claim 1, wherein the polyol is a polyol having 2 to 4 functional groups. 8. The polyol has a hydroxyl group of 20 to 60.
The toner supply roll according to any one of claims 1 to 5, which contains mgKOH / g. 9. The toner supply roll according to claim 1, wherein the polyol contains at least 5 mol% of ethylene oxide. 10. The prepolymer, the polyol,
The foam stabilizer, the catalyst, and water have an NCO index of 60.
The toner supply roll according to any one of claims 1 to 9, wherein the toner supply roll is mixed so as to be about 105.