JP2000110891A - Flame retardant rubber belt for oa equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfy the flame retardant standards, increase the ozone resistance, and reduce the permanent set by setting chloroprene rubber and ethylene propylene rubber to the major components and by specifying the quantity of aluminum hydroxide powder adding thereto. SOLUTION: Chloroprene rubber and ethylene propylene rubber are set to the major components of the rubber and aluminum hydroxide powder 1-100 pts.wt. is added to the rubber components 100 pts.wt. If it is less than 1 pts.wt., no flame retardant performance is obtained, and if it exceeds 100 pts.wt., the permanent set is enlarged. The weight ratio of the chloroprene rubber to the ethylene propylene rubber 99/1-40/60 shows superior balance between the ozone resistance and the flame retardant performance and the characteristics such as the permanent set become favorable in 90/10-60/40. This constitution satisfies the flame retardant standards as the OA equipment parts, even if the thickness is set to 1 mm or less, and especially 0.4 mm, provides it with the superior ozone resistance, and reduce the permanent set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endless rubber belt used for conveying originals and papers and transferring images in an image forming apparatus in so-called OA equipment such as a copying machine, a printer and a facsimile. The present invention relates to a belt having excellent properties.

[0002]

2. Description of the Related Art In a so-called OA device such as a copying machine, a printer, a facsimile, etc., a power supply is turned on day and night.
Many are used in the state of fire, from the viewpoint of fire prevention,
The safety of the OA equipment as a whole is specified, and it is required that, in addition to resin products such as a housing, each component used therein passes a predetermined flame retardant standard.

In the above-mentioned OA equipment, those which form an image by a so-called electrophotographic method are charged by corona discharge using a high voltage as a means for charging a photosensitive member. Due to the high concentration, the rubber parts used are required to have ozone resistance.

Further, the belt is usually used for a long period of time in a state where a predetermined tension is applied by a plurality of rollers and the belt is continuously subjected to dynamic deformation. It is also required that the elongation is small.

[0005] As an example of a rubber belt used in OA equipment, a transfer belt that satisfies flame retardancy and ozone resistance and that uses chloroprene rubber and ethylene propylene rubber as rubber materials is well known ( JP-A-9-179414).

In general, it is well known that the addition of antimony trioxide (Sb ₂ O ₃ ) is effective in making a rubber flame-retardant. The flame retardancy is also related to the thickness of the sample, and it is also known that the greater the thickness of the same material, the higher the flame retardancy.

[0007]

However, a belt using antimony trioxide has a large permanent elongation and is required to have high performance such as clear image formation and accurate paper feeding.
In equipment parts, such permanent elongation may cause a decrease in these functions in long-term use, and further improvement is required.

Further, when the thickness of the belt is simply increased to improve the flame retardancy, the tension required for mounting the belt increases, and the tension roller, the frame supporting the roller, and the photosensitive member in contact with the belt are increased. It is necessary to increase the strength of the shaft and the like, which is not preferable.

An object of the present invention is to satisfy a predetermined flame retardant standard required for OA equipment parts, to have excellent ozone resistance, to have a small permanent elongation, and to maintain the rigidity of the entire belt at 1 mm or less. In particular, it is an object of the present invention to provide an endless rubber belt that passes a predetermined flame retardant standard even if the thickness is 0.4 mm or less.

[0010]

According to the present invention, there is provided an OA comprising chloroprene rubber and ethylene propylene rubber as main components of a rubber component, and 1 to 100 parts by weight of aluminum hydroxide powder added to 100 parts by weight of the rubber component. The present invention relates to a flame-retardant rubber belt for equipment.

A rubber belt having such a composition passes a predetermined flame-retardant standard required for OA equipment parts even when the thickness is 1 mm or less, particularly about 0.4 mm, and has excellent ozone resistance and low permanent elongation. It has excellent characteristics as an endless rubber belt for OA equipment parts. In particular, the flame retardancy that cannot be achieved by the conventional technology is UL94.
Evaluation by the VTM method achieved VTM-0,
% Elongation, a rubber belt having a permanent elongation at 50 ° C. for 24 hours of 7% or less can be obtained.

The rubber belt of the present invention is particularly suitable for a semiconductive belt. A semiconductive rubber belt used in an image forming apparatus of a copying machine is required to have an electrical resistance value that does not change with long-term use. The semi-conductivity of the belt is usually given by the addition of carbon black, and it is considered that the semi-conductivity is exhibited by the continuous structure of the carbon black in the rubber molded body. Used for a long time in the stretched state,
When the semiconductive belt undergoes a large permanent elongation, the continuity of such a carbon black structure is partially lost, resulting in an increase in electric resistance, which may affect image formation. The semiconductive belt of the present invention has an effect that the influence on image formation is small because permanent elongation is suppressed to a low level.

Since the belt as the paper-feeding member has a small permanent elongation, the effect that the paper-feeding accuracy hardly deteriorates even when used for a long time can be obtained.

If the amount of the aluminum hydroxide powder is less than 1 part by weight with respect to 100 parts by weight of the rubber component, the desired flame retardancy cannot be obtained. If it exceeds 100 parts by weight, the permanent elongation becomes large, which is not preferable. . It is more preferably 10 to 80 parts by weight in terms of excellent balance between physical properties and flame retardancy.

In the flame-retardant rubber belt of the present invention, the weight ratio of the chloroprene rubber / ethylene propylene rubber is preferably from 99/1 to 40/60.

In this range, the balance between ozone resistance and flame retardancy is particularly good and preferable. Particularly preferably,
The weight ratio of chloroprene rubber / ethylene propylene rubber is in the range of 90/10 to 60/40, and characteristics such as permanent elongation are more excellent.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As the ethylene propylene rubber used in the present invention, known ethylene propylene rubbers can be used without particular limitation, and ethylene propylene rubber (EPD) obtained by copolymerizing a diene monomer such as norbornadiene is used.
Both M) and ethylene propylene rubber (EPR) which does not use a diene monomer can be used.

It should be noted that other known rubber materials may be used in combination as long as the objects and characteristics of the present invention are not impaired.

As a material of the rubber belt of the present invention, it is a preferable embodiment to use other additives in addition to aluminum hydroxide depending on the use and purpose. Specifically, the additives exemplified below can be used for the purpose mainly of imparting the added characteristics and improving the characteristics.

Carbon black: Improve the physical strength of rubber, impart conductivity. Titanium oxide: Create white belt. Pigment: Create colored belt. Silica powder: Create white belt, improve physical strength, etc. Process oils, plasticizers: adjustment of rubber hardness, imparting of flexibility, improvement of processability, etc. ・ Surfactant: improvement of dispersibility of fillers, etc. ・ Internal release agent: improvement of mold release properties -Antioxidants, antioxidants, antiozonants: improvement in durability, etc. In addition to the above additives, metal soaps such as stearic acid, calcium stearate and zinc stearate, and inorganic materials such as calcium carbonate and zinc oxide. Known rubber compounding chemicals can be added, and it is also preferable to add graphite, metal powder, etc. together with carbon black when imparting conductivity. In the belt of the present invention, it is not denied that antimony trioxide or magnesium oxide is used within a range that does not affect properties such as permanent elongation.

The rubber belt of the present invention is crosslinked to form a molded article. As a crosslinking method, sulfur vulcanization, peroxide crosslinking,
Known crosslinking methods such as resin vulcanization can be used. The crosslinking method and the chemicals that can be used for crosslinking (vulcanization) are described in “Basics of Rubber Technology”, edited by The Japan Rubber Association (Japan Rubber Association).

The above materials are kneaded by known means,
Unvulcanized rubber sheet with a predetermined thickness through a calender roll, ribbon shape using a slitter from a kneading roll, or unvulcanized rubber in a ribbon shape or belt shape extruded from an extruder It is supplied to the vulcanization molding process.

As a method for forming the rubber belt, a known forming method can be used without any particular limitation. Specifically, a compression molding method using a press, a method in which a belt-shaped unvulcanized rubber obtained by extrusion is molded using a mandrel, and a ribbon-shaped unvulcanized rubber obtained in the above process. An injection molding method using rubber or the like is exemplified.

A method of forming a rubber belt having a volume resistivity in the range of 10 ⁴ to 10 ¹² Ω · cm used in an image transfer apparatus includes extrusion molding from the viewpoint of preventing non-uniformity of resistance caused by shear stress. It is preferable to use an extrusion molding method in which a belt-shaped unvulcanized rubber is extruded into a tube shape by a method, coated on a mandrel, and vulcanized under pressure.

The vulcanized belt can be used as it is, but it can also be used after being polished to a predetermined thickness. Further, at least one of the front and back surfaces is used for improving surface characteristics. It is also a preferable embodiment to provide another material layer, and for example, formation of a coating layer having lubricity for improving the cleaning property of the attached toner is exemplified.

[0026]

Embodiments of the present invention will be described below. The raw materials used are summarized in Table 1.

[0027]

[Table 1] In addition, Heidilite H-32 has an average particle diameter of 8 μm, Heidilite H-42M has an average particle diameter of 1.0 μm, and Noxeller # 22, Noxeller TS, and Noxeller CZ used as accelerators are all Ouchiuchi. It is a product of Shinko Chemical.

(Examples and Comparative Examples) After kneading in the usual manner according to the composition shown in Table 2 to form a ribbon, it was extruded into a tube having a diameter of 100 mm, a thickness of 1.4 mm and a width of 250 mm. It is molded and coated on a mandrel having a diameter of 102 mm and a width of 280 mm, and has a vapor pressure of 5.5 kg / cm ² (about 1 kg / cm ² ).
A belt sample was prepared by heating and vulcanizing in a steam vulcanizer (60 ° C.) for 60 minutes, and the belt sample was polished on both sides and evaluated as a polished belt having a thickness of 0.4 mm.

[0029]

[Table 2] (Evaluation) (1) Flame retardancy evaluation 200 m longer than the above-mentioned polishing belt having a thickness of 0.4 mm
Cut out an evaluation sample with a width of 50 mm and a width of 50 mm, and UL standard UL-
The flame retardancy was evaluated according to the 94 VTM method.

(2) Permanent elongation A strip-shaped evaluation sample having a width of 10 mm and a length of 130 mm was cut out from the polishing belt, and the distance between the reference lines was 90 mm (L ₀ ), and the distance between the reference lines was 135 mm (50% elongation). In a stretched state at 50 ° C. for 24 hours. After releasing the extension, leave it at room temperature for 10 minutes, and set the distance between the marked lines (L ₁ ).
Was measured, and the permanent strain was determined by the following equation. Permanent set (%) = 100 (L ₁ −L ₀ ) / L ₀ (3) Physical properties Hardness, 100% elongation modulus, tensile strength, elongation at break,
The tear strength was measured according to JIS K6301.

The results of the evaluation are shown in Table 3.

[Table 3] From these results, the belt of the present invention has a small permanent elongation,
Moreover, even with a thin belt polished to a thickness of 0.4 mm, the flame retardancy of the belt passed UL94 VTM-0. On the other hand, belts using flame retardants such as antimony trioxide, magnesium hydroxide, and ammonium polyphosphate are not satisfactory in one or both of flame retardancy and permanent elongation, and particularly have a thickness of 1 mm or less. None of the thin belts had a flame retardance of UL94VTM-0 and a permanent elongation of 7% or less.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/16 G03G 15/00 (72) Inventor Riichiro Ohara 1-17-18 Edobori, Nishi-ku, Osaka-shi, Osaka Toyo Tire & Rubber Co., Ltd. F-term (reference) 2H032 BA09 BA18 2H076 AA51 BA22 3F049 BA11 LA02 LA05 LA07 LB02 LB03

Claims (2)

[Claims] 1. A flame-retardant rubber belt for OA equipment comprising chloroprene rubber and ethylene propylene rubber as main components of a rubber component and 1 to 100 parts by weight of aluminum hydroxide powder added to 100 parts by weight of the rubber component. 2. The chloroprene rubber / ethylene propylene rubber weight ratio is from 99/1 to 40/60.
The flame-retardant rubber belt for OA equipment according to 1.