JPH0361533A - Rubbery surface layer material - Google Patents

Abstract

PURPOSE:To obtain a surface layer material having a small friction coefficient, no stickiness and excellent stain resistance by integral-blending or coating a perfluorocarbon silane compound to a rubber base material. CONSTITUTION:A perfluorocarbon silane compound is integral-blended or coated to a rubber base material. It is desirable that a silicone rubber is selected as a material used as the rubber base material, but a fluoro rubber, an urethane rubber, and other rubber materials can also be used. When the perfluorocarbon silane compound shown in formula is integral-blended into the rubber base material and a rubber blade or a rubber roll, at least a surface layer section of which has the mixture, is formed, the silane compound transfers to the rubber base-material surface layer, and perfluoroalkyl groups are arrayed. Accordingly, the surface of perfluorocarbon acquired has properties such as rigid feeling, water and oil repellency, non-cohesion, etc., thus lowering the friction coefficient of the surface of a rubber molded form.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a charging device for a developing machine in an electrostatic electrophotographic apparatus such as an electrostatic copying machine (hereinafter referred to as PPC) or a laser printer (hereinafter referred to as LBP). The present invention relates to a rubber-like surface material useful for blades, fixing rolls, etc., and in particular to a rubber-like surface material that has a small coefficient of friction, is non-adhesive, and has excellent stain resistance.

(Prior Art) Rubber materials such as silicone rubber, fluororubber, and urethane rubber have come to be used as materials for triboelectric charging blades, fixing rolls, etc. of electrostatic electrophotographic devices.

In this electrostatic electrophotographic process, an electrostatic N image is developed and visualized using a charged powder called toner.
(2) In the case of PPC, an analog optical system such as an exposure lamp, lens, mirror, etc.
In the case of BP, an exposure process that uses a laser scanning optical system such as a polygon mirror to form an electrostatic latent image with a (+) charge corresponding to each original pattern on the photosensitive drum; (3)
A magnet roll (hereinafter referred to as a developing roll) on which a thin layer of (-) charged toner is attached is brought into contact with the photosensitive drum, and the toner is transferred onto the (+)-charged electrostatic latent image to form a toner pattern. (4) A transfer corona discharger supplies (+) charge from the back of the paper to transfer the toner pattern on the photosensitive drum to transfer plain paper (hereinafter referred to as PPC paper), and then the photosensitive drum Transfer process for peeling off PPC paper: (5) P with toner pattern attached
PC paper is passed through a nip of a fixing roll consisting of a heat roll and a backup roll.

A fixing process in which the toner is press-fitted and fixed into the paper fiber structure by thermocompression bonding;

There are two types of PPC development methods: a one-component development method that uses a non-magnetic toner alone, and a two-component development method that uses a non-magnetic toner mixed with a magnetic particle carrier such as iron powder or ferrite powder with a particle size of 10 to 100μ. Conventionally, the latter was the mainstream, but the former has a simple, compact, and
Because it has the advantage of not requiring toner concentration control or stirring mechanism, it has recently become popular to use low-speed printers such as personal copy machines.
It is being adopted in PCs.

This non-magnetic toner consists of a thermoplastic resin binder (copolymerized polyester, polyethylene, styrene-acrylonitrile copolymer resin, etc.), a colorant (carbon black in the case of black toner), a charge control agent (electron-accepting organic compound, etc.) and Contains other additives (hydrophobic silica, metal salts of fatty acids, etc.) Particle size: 5-25Im, Softening point: 70-8
These particles are amorphous or spherical particles at 0° C. In a two-component development system, they are mixed with the above-mentioned magnetic particle carrier and coated with toner on a photosensitive drum using a magnetic brush developing machine or the like.

The charged friction blade is used in the above-mentioned l-component type phenomenon method using non-magnetic toner, and with a simple mechanism of pressing this blade against the developing roll, the toner is charged with a (-) charge and a constant thickness is applied to the developing roll surface. This forms a toner layer.

Here, this process will be explained in detail according to the attached drawings. As shown in FIG. Due to the rotation of the developing roll 3 having minute irregularities on the surface, toner particle groups 6
reaches the pressure of the blade 4 where it is sheared to form a uniform thin layer of toner. ■During this process of thinning, the toner particles are subjected to frictional shear from the blades and rolls (-
) acquire a charge. (2) The thin layer of charged toner particles adheres to the surface of the developing roll and reaches the transfer position of the photosensitive drum 7. As shown in FIG. 2, the charged friction blade is made by integrally molding a rubber sheet 9 of a certain thickness on one side of a spring steel strip 8 made of stainless steel, etc., and is attached to the copper strip through a hole 10.
Therefore, it is used by setting it in a developing device as shown in FIG.

(Problems to be Solved by the Invention) If a friction-charging blade made of a rubber material with excellent wear resistance is used, toner will stick to the contact surface between the blade and the developing roll and inhibit layer formation. Among these, silicone rubber is used because it has the poorest wear resistance. (Looking at the abrasion resistance in the JIS rubber material performance comparison table,
Items that are considered to be "R" include natural rubber, IR, SBR, and B.
RlCR, EVA, C8M, chlorinated polyethylene, urethane rubber, fluororubber, etc. are considered "good", while NBR, IIR, EPDM, epichlorohydrin rubber, acrylic rubber, etc. are also "fair". To things,
Silicone rubber is mentioned. ) According to the results of experiments conducted by the present inventors, rubbers other than silicone rubber are unsuitable for use as a friction charging blade because they cause layer formation inhibition due to toner adhesion. In short, the required characteristic for this blade material is that it wears away due to the formation of a toner layer and always exposes a new rubber surface.

However, there is a problem with medium and high speed PPC support. In other words, while low-speed PPCs such as personal copiers can copy 5 to 15 A4 sheets per minute, medium-speed PPCs are required to copy 20 or more pages, and high-speed PPCs are required to copy 50 or more sheets per minute. When a triboelectrically charged blade is used in medium-to-high speed PPC, the problem is that it wears out quickly and must be replaced frequently, making maintenance complicated.

On the other hand, in the above fixing process (Fig. 3), the heat roll 11 is required to have high heat resistance and good releasability from the toner, so the metal core (cylinder) 13 containing the heater 12 is Tetrafluoroethylene (PTF)
A coating layer 14 of fluororesin such as E) is provided, or a tube 14 made of fluororubber such as vinylidene fluoride/propylene hexafluoride copolymer is coated.

In addition, the backup roll 15 is required to be heat resistant, to have excellent compression recovery properties in this high temperature range, and toner releasability and paper feeding properties (paper does not wrap around the roll), so a silicone rubber roll is required. used. especially,
For this purpose, from the viewpoint of paper feeding properties, it is better for the entire roll system to be flexible and the surface layer to be hard, so we applied the silicone rubber sponge core to the surface.

A silicone rubber layer with a rubber hardness (JIS-A) of 50 to 70"Hs is used. However, this backup roll is first coated with silicone rubber on a metal core (rondo or cylinder) 16 by a mold foam press molding method. After the sponge 17 is integrally molded, the surface is polished, and it is set at the axial center of a cylindrical casting mold to form the final roll shape, and room temperature or low temperature vulcanized silicone is poured from the axial end of this mold. It is manufactured using a complicated method of injecting rubber (hereinafter referred to as RT silicone rubber) 18 and pulling it out of the mold after curing, which increases costs. The drawback is that the toner releasability is not good and it gets dirty easily.On the other hand, rolls made of fluororubber alone have a high material cost and have a rubber hardness (JIS-A) of 60'Hs.
Because of the above-mentioned hard materials, paper feeding properties are poor.

(Means for Solving the Problems) The present invention relates to a rubber-like surface layer material useful as a rubber roll or rubber blade that solves the above-mentioned disadvantages. The main purpose of this document is to ensure that the

As mentioned above, it is desirable to select silicone rubber as the material used as the rubber base material in the rubber-like surface material of the present invention. It can also be used as a cleaning blade to scrape off and clean residual toner, and in the case of rubber rolls, it can also be used on platen rolls for facsimiles, thermal printers, etc.
, fluororubber, urethane rubber, EPDM, NBI <, CR1, considering that it can be used for various paper feed rolls such as facsimiles, printers, word processors, and personal computers.
Chlorinated polyethylene and other rubber materials can also be used.

The perfluorocarbon silane compound applied to the present invention is represented by the general formula [wherein, OR is an alkoxy group such as a methoxy group (-0CH,), and X is 2 or 3].

When this silane compound is coated as a solvent solution or an aqueous solution on the surface of a base material such as a rubber blade or a rubber roll, the alkoxysilane group (-8i (OR)) absorbs moisture from the air in the aqueous solution.

Alternatively, it is hydrolyzed by moisture adsorbed on the substrate surface to form a silanol group [-8i(OH)), which forms a hydrogen bond with the hydroxyl group on the substrate surface or undergoes a dehydration condensation reaction to form a strong bond. A perfluoroalkyl group (CnF2n+1-) is immobilized on the surface of the substrate.

Furthermore, when this silane compound is integrally blended into a rubber base material to form a rubber blade or rubber roll having it at least in the surface layer, the silane compound migrates to the surface layer of the rubber base material, and perfluoroalkyl groups are arranged. . The surface of the perfluorocarbon obtained in this way has a hard texture.

Perfluorocarbon silane compounds that have properties such as water repellency, oil repellency, and non-adhesiveness and reduce the coefficient of friction on the surface of rubber moldings include a: CF, CH, CH, Si (OCH, )3b
:CF, (CF,)3CH,CH,5i(OCR,)
3c: CF3(CFi)7CH2CH2Si(OC
H))3CF, (CF, ), CH, CH, 5i (OCR
,)! e: CF3 (cFs), coocH, cH2c
H2s 1(OCH3)3f: CF, (CF,), C
08CH, CH, CH25i (OCH,).

g: CF3(CFa)s CON HCHz
CHz CHz S i (OCz Hs)sh:OF
, (CF,)7So2NHCH,CH,CH,5L(O
CH3)3j: CF3 (CF, ), CH, CH, SC
H,CH,5i(OCH3)ik:CF3(CF't)
sCHICH! SCH,CH,5L(OCH3)3Go
(CF,), CF3 1: CF, (CF2), C0NHCH, CH, NC
H2CH,CH.

(cHio)asi SQ, (CF, ), CF3 rn: CF, (CF2)7SO, NHCH, CH, N
CH, CH, CH.

(CHaO)3Si Examples include.

The properties of perfluorocarbon surfaces are evaluated by the critical surface tension γ. In other words, only a liquid with a surface tension less than the critical surface tension γ can wet the perfluorocarbon surface, so the smaller γ is, the more difficult it is to wet the surface, and this difficulty in wetting is due to the hardness, It is an indicator of water repellency, oil repellency, non-adhesiveness, etc. This hard-to-wet surface is γ 〈approx. 15d
Obtained when yn/am.

The perfluorocarbon silane compound that provides the above characteristics has a perfluoroalkyl group having 7 or more carbon atoms. Even for perfluoroalkyl groups of the same length, γ differs depending on the structure of the hydrocarbon chain, and those with polar groups such as amide groups, sulfonic acid amide groups, and carboxylic acid amide groups have a lower γ.

For example, N −[3−(
It is preferable to use trimethoxysilyl)propyl core fluoroheptylcarboxylic acid amide, N-(3-(trimethoxysilyl)propyl)-N-n-propylperfluorooctylsulfonic acid amide shown by formula i, and the like.

Here, for reference, the γ (unit: dyn/am) of each perfluorocarbon silane compound exemplified above is listed as follows.

a: 20.6, b: 17.3, c: 13.8, d:
15.3, a: 17.4, f: 15.5,
g: 14°4, h: 13.0, i: 13.
O,j: 14.7, k: 14. O,l: 10
．． 6. m: 10.4° Also in the case of an integral blend, the perfluoroalkyl group with a larger number of carbon atoms is more likely to be oriented in the surface layer, so it is preferable that the number of carbon atoms is 7 or more.

As for the treatment method for rubber blades and rubber rolls, in the case of rubber blades, the integral blending method is preferable since wear is assumed, and in the case of rubber rolls, the coating method may be used, but if the thickness of the perfluorocarbon silane layer by coating is 0.1 Since the coating film is as thin as ~0.5 g/rrr and there is a problem in the durability of the coating film, it is also preferable to use the integral blending method.

Furthermore, in consideration of paper feeding properties, rubber hardness (JIS-A
) is 30 to 40'Hs and a rubber material containing no perfluorocarbon silane compound is used as the core (Fig. 3 17),
If the rubber roll has a rubber hardness (JIS-A) of 60 to 70'Hs and has a surface layer made of a rubber material that is an integral blend of the above-mentioned silane compound (Fig. 3, 18), the relatively expensive silane compound can be saved. Moreover, since it can be manufactured by a general two-layer extrusion method, the cost of the final roll product can be kept low.

Integral blending of this perfluorocarbon silane compound into rubber materials such as silicone rubber is carried out by mixing two rolls of 100% stock solution of this silane compound into a rubber compound using a rubber mixer such as a Banbury mixer. This is done by kneading.

In this case, the ratio of the blend of the silane compound to 100 parts by weight of the rubber material is preferably selected within the range of 0.5 to 5 parts by weight while experimentally measuring the coefficient of friction.

On the other hand, when coating this silane compound, dissolve this compound in an organic solvent such as ethyl alcohol or isopropyl alcohol, and then apply it to the surface of a base material such as a rubber blade or rubber roll.

This is done by coating by dipping, spraying, brushing, etc., and then heating and drying at a temperature of about 100° C. for 5 to 30 minutes. The thickness of the coating film is 0
．． It is recommended to select from the range of 0.05 to 0.5 g/rf,
Generally, at 0.1 g/rrf, a surface comparable to that of a fluororesin is formed, and since the rubber-like surface layer material of the present invention is subject to wear by toner particles and PPC paper, it is desirable to set the amount at about 0.5 g/rrf.

The above description has been made using rubber rolls and rubber blades as examples of articles provided with rubber-like surface materials, but the present invention is applicable to any field where the characteristics of having a small coefficient of friction, no stickiness, and excellent stain resistance are utilized. The present invention is not limited to these uses, and can be used, for example, as a surface layer material for guides, various holding plates, etc. in electrostatic electrophotographic devices.

(Action of the invention) The rubber-like surface material according to the present invention is made by integrally blending or coating a perfluorocarbon silane compound on a rubber base material, so it has a small friction coefficient, is non-sticky, and has stain resistance. It is excellent and extremely useful as a triboelectric charging blade for a developing machine, a fixing roll, etc. in an electrostatic electrophotographic device.6 (Examples and Comparative Examples) Below, one typical embodiment of the present invention will be explained with reference to Examples and Comparative Examples. .

Example 1. and Comparative Example 1 Silicone rubber KE-951U (manufactured by Shin-Etsu Chemical Co., Ltd., trade name) with a rubber hardness (J l5-A) of 50"Hs 100
After kneading 2 parts by weight of vulcanizing agent C-8 (manufactured by Shin-Etsu Chemical Co., Ltd., trade name) per part by weight, N-(3-(trimethoxysilyl)propyl)-Nn-propylperfluorooctyl Sulfonic acid amide MF-160 (Mitsubishi Metals ■,
Rubber compound A&! containing 2 parts by weight of product name). 1
Rubber compound B was also prepared by removing MF-160 from this formulation.

Next, press molding to a thickness of 0,1 m x width of 25
■× On the surface of a 5US304 steel strip with a length of 300 m, align the ends in the width direction as shown in Figure 2, and make a thickness of 1 m.
A rubber sheet of 10 tm x 300 mm in length was formed into an integral bottom shape using the above rubber compounds A and B to produce triboelectric charging blades A and B. Frictionally charged blade B corresponds to that currently in use.

The coefficient of kinetic friction of this triboelectrically charged blade was measured using a friction meter TR model (manufactured by Toyo Seiki Seisakusho, trade name) at a friction speed of 500.
When measured in m/min, charging blade B was 1.25, while charging blade A was 0.85.

In addition, the developing machine F'X-27 for charging blade wear test
00 (manufactured by Fuji Xerox ■, trade name), the surface of this developing roll (φ25 m) was polished in the axial direction with #800 sandpaper, cleaned with ethyl alcohol, and then pressed with a linear pressure of 0.3 kg/as. Attach a friction charging blade so that
The blade was rotated at 0 mm/see (460 rpm) for 60 minutes, and the wear depth of the blade was measured. As a result, charging blade B, which is equivalent to the current product, had a wear depth of 11 to 12 μm, whereas charging blade A had a lower wear depth of 6 to 7 μm, showing twice the wear durability of the current product. Furthermore, the toner layers of charging blades A and B were uniformly formed to have a thickness of 20 to 30 IU, and no clogging due to toner adhesion occurred.

Example 2 Silicone rubber KE-172U (manufactured by Shin-Etsu Chemical @, trade name) with rubber hardness (J I 5-A) 70' Hs 10
Vulcanizing agent C-2 (manufactured by Shin-Etsu Chemical @,
Product name) After blending 2 parts by weight.

A rubber compound A2 was prepared containing 2 parts by weight of N-(3-(trimethoxysilyl)propylcoperfluorohebutylcarboxylic acid amide, MF-150 (manufactured by Mitsubishi Metals, trade name).Next, rubber hardness was determined. (JIS-A)25
°Hs silicone rubber 5E1642U (manufactured by Toray Silicon ■, trade name) 100 parts by weight, vulcanizing agent RC
-1 part by weight of 2FD (manufactured by Toray Silicone M, trade name) was blended, and a soft layer with a diameter of 2
2. A silicone rubber roll with a hard layer thickness of 1.5 m, that is, an outer diameter of 25 mm, was molded. When this was used as a backup roll for a PPC fixing roll, it was used with little toner adhesion and good paper feeding performance.

(Effects of the Invention) The rubber-like surface material according to the present invention has a perfluorocarbon layer formed by applying a perfluorocarbon silane compound to a rubber base material such as silicone rubber by integral blending, which is a common kneading method, or by a simple coating method. This surface layer has properties such as hard texture, water/oil repellency, and non-adhesion.

The coefficient of friction of this surface layer material can also be increased by controlling the blending ratio of the silane compound to the rubber base material in the case of an integral blend, and the dissolution ratio of the silane compound to the solvent in the case of coating. It can be adjusted arbitrarily.

Therefore, when this is applied to a charged friction blade, the friction coefficient can be lowered compared to conventional silicone rubber blades, and the wear resistance during toner layer formation is improved, resulting in medium and high speed PPc. It becomes possible to respond to

In particular, when silicone rubber was selected as the rubber base material for this surface material, it met the basic requirement of toner layer formation, which was to always expose a new surface, and it did not work as well as when other rubber materials were used. Does not cause layer formation failure due to toner sticking.

On the other hand, in the case of a rubber roll such as a fixing roll, the inner layer of the roll is soft and the surface layer has a hard feel and can be made non-adhesive, so it is possible to obtain a roll that has good paper feeding properties and does not have toner attached. This property is also effective when applied to other paper feed rolls and platen rolls.

Furthermore, silicone rubber products have traditionally been used in medical parts such as O-ring backings, rubber caps, rubber droppers, and rubber tubes.
This silicone rubber product is sticky and difficult to align with an automatic alignment machine, making automatic setting difficult. However, by applying the product of the present invention, automatic setting becomes easier.

In addition, the platen roll of thermal printers such as facsimile machines uses conductive rubber rolls to prevent static electricity, but when paper is pressed against the platen roll with a thermal head, the paper becomes stained black if it is a carbon-containing conductive rubber roll. For.

Usually expensive antimony oxide dope, titanium oxide,
A white conductive rubber roll containing tin oxide powder is used. However, by applying the surface layer material of the present invention to a carbon-containing conductive rubber roll, an inexpensive conductive rubber roll free from paper stains can be provided.

Furthermore, conductive rubber containing metal powders such as Ag, Ni, and Cu is used for interconnectors and electromagnetic shielding materials, and rubber magnets containing Sm-co magnetic powder, Nd-Fe-B magnetic powder, etc. are used for motors. When the product of the present invention is applied to this, water repellency is imparted to the surface of the rubber base material, so oxidation of metal components, which has been a problem in performance deterioration, can be effectively prevented.

[Brief explanation of drawings]

The drawings all relate to embodiments of the present invention; FIG. 1 is a longitudinal cross-sectional view of a developing device, and FIG. 2 is a cross-sectional view of a developing device used in the device shown in FIG. FIG. 3 is a perspective view of the f1 charging blade and a longitudinal sectional view of the fixing device. 1...Developing device 2...Hopper-shaped container 3...Developing roll 4...Frictional charging blade 5...Recovering blade 6. ...Toner particles 7...Photosensitive drum 8...Spring steel 1! F 9...Rubber sheet 10...Mounting hole 11...
・Heat roll 12... Heater 13.1
6...Metal core 14...Fluororesin coating layer 15...Backup roll

Claims (1)

[Claims] 1. A rubber-like surface material formed by integrally blending or coating a perfluorocarbon silane compound on a rubber base material. 2. A rubber roll comprising the rubbery surface material according to claim 1 on at least its surface layer. 3. A rubber blade comprising the rubber-like surface material according to claim 1 provided at least on its surface layer.