JPH04102883A - Separating pawl for copying machine - Google Patents

Abstract

PURPOSE:To provide the separating pawl which withstands the temp. of the fixing roll of a high-speed copying machine. maintains the front end shape with substantially no change and obviates the sticking of toners by subjecting a resin compsn. prepd. by kneading a polyimide resin expressed by specific constitutional formula and a fluororesin at a specific ratio to compression molding and calcining. CONSTITUTION:The polytetrafluoroethlylene (PTFE) resin is added at the specific compounding ratio to the polyimide resin formed by bringing pyromellitic anhydride and diaminodiphenyl methane into reaction and the mixture is mixed by a mixer. The polyimide resin is added at 40 to 90wt.% and the fluororesing at 60 to 10wt.% at this time. The compd. obtd. as shown by the constitutional formula (I) is compression molded in such a manner. The molding is thereafter sintered for about 4 hours at about 380 deg.C in a nitrogen atmosphere. The heat resistance and the release property of paper are improved in this way and a coating stage is omitted at the time of production. A paper jam is prevented even if some wear at the pawl tip arises.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a separating claw for copying machines (including laser beams, etc., hereinafter simply referred to as copying machines), which prevents paper jams even during high-speed copying. This invention relates to a separation claw for a copying machine.

[Conventional technology]

Conventionally, separating claws for copying machines have generally been made by injection molding and heat treatment of polyamideimide resin, polyphenylene sulfide resin, etc., and then coating the surface with fluororesin.

[Problem to be solved by the invention]

In recent years, as the speed of copying machines has increased, the temperature of the fixing roll has increased to 180℃.
The temperature rises to 220°C and at the same time, the diameter of the fixing roll becomes 40 to 50° or more, and the shape of the tip of the peeling part of the separation claw changes (deformation), and the coating film wears out.
Toner adheres to the tips of the separation claws and causes paper jams, making it necessary to replace the separation claws more frequently and to clean the separation claws more frequently.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a separation claw for a copying machine that can withstand the temperature of the fixing roll in a high-speed copying machine, is less likely to change its tip shape, and does not attract toner even if the tip is worn to some extent.

[Means to solve the problem]

The separation claw for a copying machine of the present invention is characterized by compression molding and firing a resin composition obtained by kneading 40 to 90% by weight of a polyimide resin represented by the following structural formula (1) and 60 to 10% by weight of a fluororesin. That is.

j11 O The separation claw for a copying machine in the present invention is a jig for separating paper wound on a definition roll of a copying machine, a laser beam, etc. from a fixing roll, and has an edge portion that comes into contact with the roll surface. .

The polyimide resin in the present invention is represented by the above structural formula (1) (in formula (I), n is an integer), and a small amount of copolymerization component may be copolymerized in addition to this.

The fluororesin used in the present invention is not particularly limited as long as it contains fluorine, but includes copolymers of two or more selected from polytetrafluoroethylene, tetrafluoroethylene, perfluorinated vinyl ether, hexafluoropropylene, etc. preferable.

Particularly preferred resins include tetrafluoroethylene called polytetrafluoroethylene resin or PFA resin, and perfluorinated vinyl ether represented by CFz=CF-0-Rf (Rf is a perfluoroalkyl group with c1 to 1°). It is a copolymer with particulate perfluorinated ether.

The blending ratio of polyimide resin and fluororesin is 40 to 90% by weight for polyimide resin and 6% by weight for polytetrafluoro resin.
It is 0 to 10% by weight.

When the proportion of polytetrafluoro resin is 60% by weight or more,
The strength of the tip of the claw is insufficient, and the tip deforms when passing paper.
Causes blockage. Furthermore, if the proportion of fluororesin is less than 10% by weight, there is no effect of preventing toner adhesion, and toner adhesion does not occur.
This can cause paper jams. Preferably, the content is 50 to 80% by weight of polyimide resin and 50 to 20% by weight of fluororesin.

Increasing the blending ratio of fluororesin improves the separation from paper and prevents toner from adhering, but the surface strength and rigidity of the nail tip (edge) decreases, so in such cases, an inorganic filler is further added. It is preferable. Inorganic fillers include glass fiber, carbon fiber, ceramic powder, calcium carbonate,
Silica, potassium titanate, etc. are preferred.

The amount of the inorganic filler to be blended is preferably 0 to 100 parts by weight, more preferably 10 to 50 parts by weight, based on 100 parts by weight of the resin composition consisting of a polyimide resin and a fluororesin.

The combination of polyimide resin and fluororesin or these and inorganic filler can be kneaded using a commonly used mixer, extruder, or the like.

The kneaded resin composition is supplied to a compression molding mold having the shape of a separating claw, and is molded into a separating claw by applying an appropriate pressure. After that, in inert gas or air at 370°C ~
It is heated and baked at 420°C for several hours.

The temperature and firing time during this firing are determined to be the most suitable conditions depending on the shape of the separating claw.

The separating claw of the present invention does not require fluororesin coating to prevent toner adhesion and paper jams unlike conventional separating claws, and even if the surface peels off slightly due to wear, it remains uniform. Since it is made of a fluororesin-containing resin composition, toner adhesion can be prevented.

〔Example〕

The present invention will be specifically explained below with reference to Examples. In addition,
In the examples, "parts" means "parts by weight."

Example 1 Polyimide resin made by reacting pyromellitic anhydride and diaminodiphenylmethane ("Tl-30" manufactured by Toshi ■)
Polytetrafluoroethylene (PTFE) resin (“Polyflon TFE M-12” manufactured by Daikin Industries, Ltd.)
) and mixed with a mixer.

Using the resulting formulation, 3t X12.5w X6
Test pieces were compression molded at 0°C and then fired at 380°C for 4 hours under a nitrogen atmosphere. Sprinkle Canon ■"NP-150"' copier toner on this test piece.
Leave this on a hot plate heated to 250°C for 10 minutes.
One set of 1-toner was melted, and then transferred onto a plate and the toner was cooled and solidified.

Thereafter, the toner on the test piece was peeled off with a flat fingernail, and the degree of difficulty was examined, and the bending strength and other properties of the test piece were measured. The results are shown in Table-1.

Table-1 0: Easily peeled off.

Δ...Removable.

×...Difficult to peel off.

Example 2 The same operation as in Example 1 was carried out using a composition in which 25 parts by weight of glass fiber (milled fiber manufactured by Nittobo) was added to 100 parts by weight of the composition shown in Example 1. The results are shown in Table-2.

Table ~2 ↓ (margins below this page) Example 3 Polyimide resin (Tl-3000 manufactured by Toshi ■) 60 parts,
40 parts of polytetrafluoroethylene resin ("Freon L169" manufactured by IC1), glass fiber ("PF" manufactured by Nittobo)
B-101'') were mixed in a Henschel mixer to make a formulation.

This mixture was filled into a mold for forming separation nails, and separation nails were molded at room temperature. Thereafter, this molded product was fired at 380°C for 4 hours in a nitrogen gas atmosphere.

This separating claw was attached to a high-speed copying machine made by Canon ■, and a copying test of A4 size paper was conducted at a speed of 60 pages per minute.
There was no paper jam at all up to 10,000 sheets.

Comparative Example 1 Polyimide resin (Tl-3000 manufactured by Toshi ■) 100
25 parts of glass fiber (“PFB-101” manufactured by Nittobo)
) were mixed in a Henschel mixer to obtain a blend. Using this, a separation claw was formed by the method of Example 1.

Using this separating claw, a copying test similar to that in Example 3 was conducted, but after passing 10,000 sheets, toner adhered to the tip of the claw, resulting in a paper jam.

Comparative Example 2 30 parts of polyimide resin (Tl-3000 manufactured by Toshi ■),
The same operations and performance tests as in Example 3 were carried out using a formulation consisting of 70 parts of polytetrafluoroethylene resin.

As a result, when 150,000 sheets of A-4 paper were passed through, a paper jam occurred due to the deformation of the tip of the claw.

〔Effect of the invention〕

The present invention is a separating claw for copying machines molded from a composition containing polyimide resin and a specific amount of fluororesin, so it has excellent heat resistance and paper peelability, and it is possible to omit the coating process during manufacturing. Moreover, since the claw metal body is homogeneous, paper jam will not occur even if the claw tip is slightly worn.

Agent: Patent Attorney Nobuo Kogawa -

Claims (1)

[Claims] 1. Polyimide resin 40 represented by the following structural formula (I)
A separating claw for a copying machine, characterized in that a resin composition in which ~90% by weight and 60% to 10% by weight of a fluororesin are kneaded is compression molded and fired. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) 2. Compression molding and baking of a composition in which 0 to 100% by weight of an inorganic filler is blended with 100 parts by weight of the resin composition according to claim 1. A separation claw for copying machines that is characterized by: