JP2843355B2 - Separation claw for copier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a separation claw for a copying machine.

[Conventional technology]

In a conventional apparatus such as a dry copying machine, an electrostatic latent image formed on the surface of a photosensitive drum corresponding to a character or a figure is converted into a toner image, and the toner image is supplied from a paper cassette. The toner image is transferred to the paper surface, and the surface is heated and pressed by a heated fixing roller to fix the transferred toner image to the paper surface, so that the toner image and the paper fibers are fused so that they do not easily separate from each other. The mechanism to do it is incorporated. Then, in order to ensure that the copy paper that has passed through the fixing roller is discharged without being wound around the roller, a method of scooping up the end of the copying machine using a separation claw while keeping the leading end of the copy paper in close contact with the outer peripheral surface of the roller is adopted. . Therefore, such a separation claw has a small frictional resistance to the outer peripheral surface of the roller, does not damage the surface, has sufficient mechanical strength, particularly high-temperature rigidity, and has sufficient accuracy in the shape of the tip. In addition, characteristics such as not adhering the toner have been required.

Particularly, in recent years, demand trends have spread from offices of large companies to offices of small and medium-sized enterprises, and further to ordinary households, and there is a strong demand for miniaturization and price reduction.
Each component of the fixing unit is also expected to be similarly miniaturized and reduced in price without losing the essential characteristics of the separation claw as described above.

Among the indispensable properties of such a separation claw, many proposals have been made on the improvement of non-adhesiveness to toner. For example, fluorinated polyethers have been proposed to meet the demand for miniaturization and cost reduction. There is a method of forming a polymer film on a separation nail (JP-A-61-236577). According to this method, it is easy to immerse in a low-viscosity liquid, and even if the shape becomes complicated due to miniaturization, the size and shape are easily maintained because it is a thin film. A non-stick coating can be applied.

However, the high-temperature rigidity, the damageability of the mating roll, the accuracy of the shape of the claw tip, and the like largely depend on the type of heat-resistant resin or filler used for the separation claw material. Examples of the separation nail material include polyimide, polyamide imide, polyphenylene sulfide, polyether ketone, polyether sulfone, polyether imide, and heat-resistant aromatic polyester. Polyimide, polyamide imide, polyetherketone, and heat-resistant aromatic polyester exhibit excellent high-temperature stiffness without a reinforcing agent or in combination with a reinforcing agent, but are expensive and can meet the demand for lower price. In addition, resins such as polyethersulfone and polyetherimide are relatively inexpensive, but have a glass transition point of around 220 ° C and are amorphous, so they soften at temperatures above the glass transition point. Since the heat resistance is too low, it can be used only in limited copiers where the heating temperature of the fixing roller is low. Since the fixing temperature is increased with the speeding up of the copying machine in recent years, it is used only for further limited applications. On the other hand, polyphenylene sulfide resin is inexpensive and has a low melt viscosity, so it has the property that it can easily fill thin or complicated parts due to miniaturization. Very advantageous. The glass transition point is
Although it is low as around 90 ° C, it is a crystalline resin, so it is based on adding heat-resistant fibers such as glass fiber, potassium titanate fiber and carbon fiber, or inorganic powder filler such as mica and talc to these fibers. The heat resistance is greatly improved by the reinforcing effect. However, when the filling amount of the reinforcing agent is large, the problem of damaging the mating roll and the tendency of poor dispersion tend to cause uneven filling of the reinforcing agent into the claw tip, resulting in reduced heat resistance or reduced tip shape. On the contrary, when the amount of the reinforcing agent is small, the melt viscosity of the polyphenylene sulfide resin is very small, so that a smooth radius of curvature at the tip of the separation claw cannot be obtained, and sometimes a sharp There is a problem that it becomes an edge (burr).
Also, depending on the type of reinforcing agent, for example, a separation claw using short fibers such as potassium titanate fiber as a reinforcing agent is inferior in mechanical strength such as bending strength and impact strength,
There is a problem that the rigidity is inferior at high temperatures, and with glass fiber or carbon fiber, even if there is no problem with the reinforcing effect, the surface roughness when forming the separation claw is large, the radius of curvature of the tip is too large, good As a result, the fixing paper cannot be scooped up smoothly, and a phenomenon that the separation direction becomes poor occurs.

[Problems to be solved by the invention]

As described above, in the prior art, in addition to excellent mechanical strength such as high-temperature stiffness, impact strength or bending strength at the tip of a claw, moldability, a molded product capable of easily obtaining a preferable radius of curvature at the tip of a claw. However, there has been a problem that a separation claw which is excellent in surface smoothness and the like, and which is inexpensive and can meet the demand for miniaturization has not been obtained.

[Means for solving the problem]

In order to solve the above-mentioned problems, the present invention relates to a polyphenylene sulfide resin of 100 parts by weight, a heat-resistant fiber having an average fiber diameter of 6 μm or less 20 to 200 parts by weight, and a glass transition point of 250 ° C.
A means for forming a separating claw for a copying machine using a polyphenylene sulfide resin composition containing 10 to 90 parts by weight of the above heat-resistant polysulfone resin as an essential component is employed.

 The details are described below.

First, the polyphenylene sulfide resin of the present invention is used as a matrix resin, and has a heat deformation temperature of 260 ° C. or more, which is excellent in heat resistance despite its low price, and has a melt viscosity different from that of other engineering plastics. Since it is lower than the so-called resin, a complicated or thin-walled portion can be easily molded, and the filling property of the fillers is excellent. However, in order to be used as a separating claw for a copying machine, the melt viscosity is so low that a smooth radius of curvature at the tip of the separating claw cannot be obtained, and sometimes a sharp edge (burr) is formed. Therefore, those having a high melt viscosity, specifically those having a melt viscosity at 300 ° C. of 6000 poise (orifice: diameter 1 mm, length 2 mm, load 10 kg) are preferable, and those having 10,000 poise are particularly preferable. And the upper limit of the melt viscosity is not particularly limited as long as melt molding is possible, but from an economical point of view, in order to enable multi-cavity injection molding, 5000
Poise or less is preferred.

Here, the polyphenylene sulfide resin is disclosed, for example, in Japanese Patent Publication Nos. 44-27671 and 45-3368, the reaction of a halogen-substituted aromatic compound with an alkali sulfide, and Japanese Patent Publication No. 46-27255. A condensation reaction of an aromatic compound as disclosed with sulfur chloride in the presence of a Lewis acid catalyst, or in the presence of an alkali catalyst or a copper salt of a thiophenol as disclosed in U.S. Pat. Although it is synthesized by a condensation reaction or the like, a specific method can be arbitrarily selected according to the purpose. In addition, the polyphenylene sulfide resin is an uncrosslinked product that is close to white immediately after the reaction such as the above-mentioned condensation and has a low molecular weight and low viscosity as it is, so that it is used for applications such as extrusion molding and injection molding. In the air, heated to below the melting point, crosslinked with oxygen, or increased the molecular weight in the condensation reaction step, extraction molding,
The solvent viscosity is changed to one suitable for injection molding and the like. The melt viscosity of Ryton P-4 (polyphenylene sulfide resin manufactured by Philips Petroleum Corporation, USA) which is commercially available for melt molding after such treatment is from 1500 to 5,000 poi under the aforementioned conditions. In order to obtain a polyphenylene sulfide resin having a melt viscosity of 1,000 poise or more, there is no particular limitation. For example, the same treatment may be performed. For example, the Ryton P-4 may be further subjected to oxygen crosslinking. In addition, such a high melt viscosity polyphenylene sulfide resin is available from TX
It is commercially available as 009.

Next, the heat-resistant fiber in the present invention refers to a molding temperature of polyphenylene sulfide resin (normally 280 to 350 ° C.)
Means fiber that can withstand, specifically, glass fiber, carbon fiber, graphite fiber, ceramic fiber, rock wool, slag wool, potassium titanate whisker, silicon carbide whisker, sapphire whisker, steel wire, copper Wire, stainless steel wire, silicon carbide fiber, aromatic polyamide fiber and the like can be exemplified. And, the shape of these fibers, the surface roughness of the separation claw molded product is small and smooth, and since a suitable range of the radius of curvature of the separation claw tip is 0.1 mm or less, preferably 0.05 mm or less accuracy is required, It is important that the fiber diameter is 6 μm or less. If such fibers are used, the surface roughness of the molded article becomes 1 to 3 μm or less, and the radius of curvature of the separation claw becomes 0.05 mm or less. Further, considering the rigidity and mechanical strength of the separation claw at high temperatures, the fiber length is preferably 0.05 mm or more, particularly preferably 0.1 mm or more. Considering the aggressiveness of the partner roller, a potassium titanate whisker or the like having a small hardness is preferable. However, since the rigidity and the mechanical strength at high temperatures are slightly inferior, the fiber diameter is 6 μm or less and the fiber length is 0.1 mm or more. , For example, glass fibers are preferably used in combination. The amount of these fibers is 20 to 200 parts by weight based on 100 parts by weight of the polyphenylene sulfide resin. Because, when the amount is less than the lower limit,
This is because rigidity and mechanical strength at high temperature cannot be maintained, and when the amount exceeds the upper limit, fluidity during molding is extremely deteriorated.

As already described, a separation claw molded from a composition comprising a polyphenylene sulfide resin and a heat-resistant fiber, for example, a glass fiber, has a large surface roughness and a too large radius of curvature at the tip. Molded products reinforced by edge transition, such as potassium titanate whiskers, are inferior in rigidity and mechanical strength at high temperatures, but use fibers with a fiber diameter of 6 μm or less, or fibers with a fiber length of 0.1 mm or more. It is possible to deal with each of them by using them alone or in combination. However, if the radius of curvature at the tip of the separation claw is also small, it is not sufficient. Even if the edge is too small and a sharp edge (burr) is obtained, or a material having a good radius of curvature is obtained at the time of mold processing, the filler can be used. If the curvature becomes very small due to the scar etc. attached to the mold due to etc. and it becomes easy for sharp edges to appear,
The high-temperature stiffness of the tip of the nail becomes low, causing thermal deformation,
There is a risk of damaging the outer peripheral surface of the roller.

In contrast, a composition in which a heat-resistant polysulfone resin is added to a mixture of a polyphenylene sulfide resin and a heat-resistant fiber eliminates such a defect, and has an appropriate radius of curvature (0.01 mm to 0.05 mm) over a long period of time. A separated claw molded product can be obtained. Here, the heat-resistant polysulfone resin is a thermoplastic resin having a high heat resistance among thermoplastic resins having a sulfone bond in a polymer main chain, such as polyether sulfone and polysulfone. The term “heat resistance” as used herein means the surface temperature of the fixing roller of a copying machine (170 to 250
It is important that the glass transition point at the endothermic start point (hereinafter abbreviated as onset) measured by a differential scanning calorimeter (hereinafter abbreviated as DSC) is 2 ° C.
It means that it is 50 ℃ or more. As such a heat-resistant polysulfone resin, for example, VICTREX HTA-7600G manufactured by ICI of the United Kingdom is commercially available. Incidentally, the amount of such heat-resistant polysulfone resin to be added, the polyphenylene sulfide resin 100
It is desirable to use 10 to 90 parts by weight based on parts by weight. If the amount is less than 10 parts by weight, it is not possible to obtain a molded product having an appropriate radius of curvature over a long period of time, and if the amount is more than 90 parts by weight, the compatibility with the polyphenylene sulfide resin deteriorates. This is because the mechanical strength is lowered, which is not preferable. In order to further increase the compatibility between the polyphenylene sulfide resin and the heat-resistant polysulfone resin, a copolymer comprising a polyphenylene sulfide portion and a polysulfone portion, or as a repeating unit in a polymer molecule May be added. Further, within a range that does not impair the object of the present invention, it is preferable to add an adhesive improver and a thixotropic agent, and other various fillers may be added. Here, the adhesive improver is added to increase the adhesion strength between the coating agent to be coated on the surface of the separated claw molded body and the separated claw molded body in order to improve the non-adhesiveness to the toner. , For example, an epoxy group, a carboxyl group, a hydroxyl group, a phenoxy group, a methylol group,
Thermosetting resins having at least one of the amino groups are preferred, and specific examples include phenolic resins and epoxy resins. In addition, the thixotropic agent, when the composition of the present invention is melted,
It refers to a substance that produces a thickening effect at a low shear rate, specifically, fine powdered silica, fine powdered talc, diatomaceous earth, and the like. Is further improved. Other fillers include antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, mold release agents, coloring agents, flame retardants, flame retardant assistants, antistatic agents which are added to ordinary resin compositions. In addition to the agent, abrasion resistance improver (eg, graphite, carbon random, silica powder, molybdenum disulfide, fluororesin, etc.), tracking resistance improver (eg, silica, graphite, etc.) and other fillers (eg, Glass beads, glass balloons, calcium carbonate, alumina, talc, diatomaceous earth, clay, kaolin, gypsum, calcium sulfite, mica, metal oxides, inorganic pigments, and other substances that are stable at 300 ° C. or higher).

[Action]

The average fiber diameter of the heat-resistant fiber added to enhance the rigidity and mechanical strength of the separation claw at high temperatures is 6 μm
By the following, to prevent adverse effects on the radius of curvature of the tip and surface smoothness, and by adding a heat-resistant polysulfone resin having a glass transition point of 250 ° C or more,
In the case of the conventional separation claw, even if a smooth curve cannot be obtained, or a sharp edge (burr) is sometimes obtained, and even if a mold having a good radius of curvature can be obtained during mold processing, it can be used for a long time. In the process, the tip shape of the separation claw deteriorates due to corrosive gas coming out of the resin or scars on the mold due to the compounded filler, etc.
It is possible to solve the disadvantage that the radius of curvature is also very small, and a sharp and too sharp edge is likely to appear. In other words, a molded product that can withstand a long-term use and maintain an appropriate radius of curvature can be obtained, and has excellent heat resistance of polyphenylene sulfide resin or excellent moldability that can be easily molded even in complicated or thin portions. It can be provided at a low price without hindrance.

〔Example〕

The raw materials used in Examples and Comparative Examples are collectively shown as follows, and the abbreviations are shown in []. In addition, the mixing of these raw materials was all expressed in parts by weight.

Polyphenylene sulfide resin [PPS-1] (manufactured by Philips Petroleum Corp., USA: Ryton P-4, melt viscosity 2000 poise), polyphenylene sulfide resin [PPS-2] (Kureha Chemical Industry: KPS # 214, melt viscosity 2000 poise) ), Polyphenylene sulfide resin [PPS-3] (manufactured by Topren Corporation: TX009, melt viscosity 1000 poise), heat-resistant polysulfone resin [HTA] (manufactured by ICI of the United Kingdom: Victrex HTA760)
0, glass transition point 260 ° C (DSC method, onset)), polyethersulfone resin [PES] (ICC, UK: Victrex PES480)
0P, glass transition point 220 ° C (DSC method, onset)), polyamide imide resin [PAI] (manufactured by Amiko, UK: Torlon 4000T, glass transition point 260 ° C (DSC method, onset)), glass fiber [GF -3] (manufactured by Asahi Fiberglass: Chapped strand,
Fiber diameter 3 μm, fiber length 3 mm, aminosilane coupling-treated product), glass fiber [GF-6] (manufactured by Asahi Fiberglass: chopped strand,
Fiber diameter 6 μm, fiber length 3 mm, aminosilane coupling-treated product), glass fiber [GF-13] (manufactured by Asahi Fiberglass: chopped strand,
13 μm fiber diameter, 3 mm fiber length, aminosilane coupling treated product), potassium titanate whisker [PTW] (Otsuka Chemical Co., Ltd .: Tismo D102, fiber diameter 0.1-0.3 μm)
m, fiber length 20-30mm), carbon fiber [CF-8] (Toho Rayon Co., Ltd .: Vesfight HTA, fiber diameter 7.2μ)
m, fiber length 6 mm) Among the above resin materials, heat-resistant polysulfone resin [HT
For (A), the pellets were averaged to 5
It was used after pulverized to 0 μm.

Examples 1 to 8: After the respective raw materials were dry-mixed in advance at the mixing ratios shown in Table 1, the mixture was fed to a twin-screw extruder (PCM-30, manufactured by Ikegai Iron Works, Ltd.). Rotation speed 50rp
Under the conditions of m, the mixture was extruded and granulated. The obtained pellets were injection-molded under the conditions of a cylinder temperature of 310 to 340 ° C., an injection pressure of 800 kg / cm ² , and a mold temperature of 130 ° C., and a plate material of width 12.7 mm, length 126 mm, thickness 3.2 mm and Fuji A test piece having the same shape as the separation claw used in the Xerox Copier Model 2700 was obtained. Among these specimens, the separation nail specimens prepared for the practical functional investigation of the quality of the separation and the damage of the roller were all fluorinated polyether polymers having isocyanate groups at the terminals (Italy After immersion in a Freon 113 solution in which 2.0% by weight of Fedbulin Z-DISOC 2000 (manufactured by Montezison) was dissolved, it was taken out of the solution and baked at about 200 ° C. for 2 hours.

The test pieces were evaluated for bending strength, rigidity at high temperature (elastic modulus retention), radius of curvature at the tip, surface smoothness, and practical functionality. These evaluation methods are as follows.

1) Flexural strength Based on ASTM-D790.

2) Rigidity at high temperature (elastic modulus retention) Using a dynamic viscoelasticity measuring device manufactured by Toyo Seiki Seisaku-sho,
Using a test piece of 4mm, length 25mm, thickness 1mm, frequency 10Hz
, A tensile stress was applied, and changes in tensile modulus with respect to temperature were determined at 25 ° C. and 250 ° C.

3) Radius of curvature at the tip Using a projector V-160 manufactured by Nippon Kogaku Co., Ltd., the range of the minimum and maximum measured values at n = 100 is shown. However, 5μ
If the diameter is smaller than 1 m, it cannot be measured with high accuracy.
It was written.

4) Surface smoothness Using a surface roughness meter (Nihon Vacuum Corporation: Dektak II type)
The surface roughness of the roller contact portion of the separation claw was measured.

5) Practical functions Using a dry copier (Fuji Xerox Co., Ltd .: Model 2700)
A test piece of the same shape as the separation claw used for it was attached, and 50,000 sheets of B4 size copy paper were passed continuously. By repeating copying, the number of copies and the degree of damage to the mating roller at the time of paper separation failure (paper jam) are checked using a surface roughness meter before and after the operation of the separating claw sliding contact portion, Rollers with a wear depth of less than 5 μm (marked with ◎), 5 to 15 μ
m (marked with 段 階) and those exceeding 15 μm (marked with △).

 Table 2 summarizes the results obtained in the above tests.

Comparative Examples 1 to 7: Specimens were prepared by performing exactly the same operation as in Example 1 except that the respective raw materials were blended at the ratios shown in Table 3.
The same properties in ~ 8 were investigated. The obtained result is
It is summarized in the table.

The following can be said from Tables 2 and 4. In other words, Examples 1 to 8 have good bending strength, and high values of tensile modulus at high temperature (rigidity at high temperature), accuracy of the radius of curvature of the tip and surface smoothness are all good values. On the other hand, even if the glass fiber having a fiber diameter of 6 μm is used, the average fiber diameter of the heat-resistant fiber is 6 μm even when Comparative Example 1 and the heat-resistant polysulfone resin not using the heat-resistant polysulfone resin are used. Comparative Example 6 or 7 using more than
Although bending strength, tensile elasticity, and the like show good values equivalent to those of the examples, the radius of curvature of the tip becomes too small, so that so-called burrs are not preferred. In Comparative Examples 6 and 7, the radius of curvature is too large due to the adverse effect of thick fibers, which is not preferable, and the surface smoothness is poor. In Comparative Example 2, a polysulfone resin having a glass transition point of 250 ° C. or lower and 220 ° C. was used, but the tensile modulus at high temperatures was extremely poor. Further, even when the glass transition point is 250 ° C. or higher, Comparative Example 3 using a polyamideimide resin, which is a resin other than heat-resistant polysulfone, is not so bad in flexural strength and tensile modulus at high temperatures, The radius of curvature of the tip from the generation to the unfilled one varies widely, and the surface has poor smoothness. This is probably because the compatibility between the base material polyphenylene sulfide resin and the polyamideimide resin is very poor. Further, Comparative Example 4 in which the amount of the heat-resistant polysulfone resin added was too large,
As a result of the decrease in compatibility as in Comparative Example 3, the bending strength is reduced, the variation in the radius of curvature of the tip is increased, and burrs are generated to unfilled ones. Also,
In Comparative Example 5 in which the amount of the heat-resistant fiber added was too small, the reinforcing effect was too small, so that the bending strength was too small, the rigidity at high temperature was small, and the radius of curvature was small.

As described above, none of Comparative Examples 1 to 7 satisfy bending strength, rigidity at high temperature, tip radius of curvature, surface smoothness, and the like. No copy was completed for 50,000 sheets, and the separation failure occurred too early, as in Comparative Example 2, except for those with little damage to the rollers. Damage was not good either.

〔effect〕

As described above, the separation claw for a copying machine made of a material having the polyphenylene sulfide resin of the present invention, a heat-resistant fiber having an average fiber diameter of 6 μm or less, and a heat-resistant polysulfone resin as essential components has mechanical strength and high temperature. Excellent rigidity, without causing paper jam or poor separation direction due to too small or too large radius of curvature of the separation claw tip.
In addition, since the surface is smooth, the separation paper does not get caught, and if necessary, a non-adhesive film such as a fluorinated polyether polymer is applied to provide excellent non-adhesion as it is in a good separation claw shape. As a result, it can sufficiently withstand long-term continuous use. Since such characteristics can be realized at low cost while maintaining the excellent moldability of polyphenylene sulfide resin, it can be said that the significance of the present invention is extremely large.

Claims (1)

(57) [Claims] 1. A polyphenylene sulfide containing 100 parts by weight of a polyphenylene sulfide resin, 20 to 200 parts by weight of a heat-resistant fiber having an average fiber diameter of 6 μm or less, and 10 to 90 parts by weight of a heat-resistant polysulfone resin having a glass transition point of 250 ° C. or more. A separating claw for a copying machine, which is a molded product of a resin composition.