JP2021192084A - Sponge roller - Google Patents

Abstract

To provide a sponge roller with high endurance.SOLUTION: A sponge roller 1 comprises a shaft body 2, and a foam elastic layer 3 formed around the outer periphery of the shaft body 2. The foam elastic layer 3 is formed by foaming and vulcanizing a millable silicone rubber composition, vinyl group-containing silicone crude rubber, foaming agent and a foam elastic layer composition containing cross-linking agent. A cured product of rubber composition obtained by removing the foaming agent from the foam elastic layer composition has loss coefficient tanδ of 0.035 or less under the following measurement conditions, where the measurement condition is frequency 8 Hz, temperature 100°C and distortion control 5 μm.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sponge roller.

Various image forming devices using an electrophotographic method are adopted in laser printers, copiers, video printers, facsimiles, and multifunction devices thereof. An image forming apparatus using an electrophotographic method has a shaft body and an elastic layer formed on the outer peripheral surface thereof, for example, a cleaning roller, a charging roller, a developing roller, a transfer roller, a pressure roller, a paper feed transfer roller, and the like. It is equipped with various printing sponge rollers such as fixing rollers.

As the fixing means in the above-mentioned image forming apparatus, for example, a thermal roller fixing method is adopted. In the thermal roller fixing method, a heating roller (fixing roller) and a pressure roller are used as a pair of basic configurations, and a recorded material (transfer material sheet, fax paper, printing) on which a toner image is carried on a pressure contact nip portion of the roller pair is used. It is common to heat-press fix the toner image on the material to be recorded by introducing paper, etc.). A foamed elastic layer (sponge layer) is used in the fixing roller or the pressure roller used for the fixing means in order to adjust the nip pressure to an appropriate level.

The foamed elastic layer is generally formed by vulcanizing and foaming a miraculous silicone rubber containing an organopolysiloxane and a filler. A fixing or pressurizing roller having a foamed elastic layer is mounted in a pressure contact state and exerts its function by continuously or intermittently rotating. Therefore, it is easily loaded by heat or friction, and the foamed elastic layer becomes Since the hardness decreases, high durability is required.
As a silicone rubber composition capable of forming a rubber member for paper feeding having high wear resistance even after repeated use, for example, in Patent Document 1, a vinyl group-containing silicone raw rubber is used as a rubber compound for forming a rubber member for paper feeding. A silicone rubber composition added, wherein the loss coefficient tan δ after smelting the rubber compound is 0 <tan δ ≦ 1 has been proposed.

Japanese Unexamined Patent Publication No. 10-182977

However, in order to meet the recent demand for providing a high-speed, high-definition, high-quality image forming apparatus, the fixing roller or the pressure roller is required to have further improved durability.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sponge roller having high durability.

The present invention is a sponge roller including a shaft body and a foamed elastic layer formed on the outer periphery of the shaft body, wherein the foamed elastic layer is a mirable type silicone rubber composition, a vinyl group-containing silicone raw rubber, a foaming agent, and the like. And the loss coefficient tan δ of the cured rubber composition obtained by foaming and vulcanizing the foamed elastic layer composition containing the cross-linking agent and removing the foaming agent from the foamed elastic layer composition under the following measurement conditions. It is a sponge roller of 0.035 or less.
<Measurement conditions>
Frequency 8Hz, temperature 100 ℃, strain control 5μm

The Asker C hardness of the foamed elastic layer is preferably 15 degrees or more and 40 degrees or less.

The sponge of the present invention is preferably a pressure roller.

According to the present invention, a highly durable sponge roller can be obtained.

It is a perspective view which shows the sponge roller of this invention. It is a graph which shows the hardness change amount of the sponge roller of an Example and a comparative example.

Hereinafter, embodiments of the present invention will be described in detail, but the following embodiments are presented for purposes of illustration, and the present invention is not limited to the embodiments shown below.

[Sponge roller]
As shown in FIG. 1, the sponge roller 1 of the present invention is a sponge roller 1 provided with a shaft body 2 and a foamed elastic layer 3 formed on the outer periphery of the shaft body 2 in this order.
Hereinafter, the details of the sponge roller 1 of the present invention will be described with reference to FIG.

(Axis body)
As the shaft body 2, preferably, a shaft body having conductivity and used for a conventionally known developing roller can be used. The shaft body 2 is preferably made of at least one metal selected from the group consisting of, for example, iron, aluminum, stainless steel, and brass. The shaft body 2 made of such a metal is also generally known by the name of "core metal".

The shaft body 2 may contain an insulating resin. The insulating resin may be, for example, a thermoplastic resin or a thermosetting resin. The shaft body 2 may include, for example, a core body made of an insulating resin and a plating layer provided on the core body. Such a shaft body 2 can be obtained, for example, by plating a core body made of an insulating resin to make it conductive.
The shaft body 2 is preferably a core metal in order to obtain good conductivity.

The shape of the shaft body 2 is preferably, for example, a rod shape, a tubular shape, or the like. The cross-sectional shape of the shaft body 2 may be, for example, a circular shape, an elliptical shape, or a non-circular shape such as a polygon. The outer peripheral surface of the shaft body 2 may be subjected to a treatment such as a cleaning treatment, a degreasing treatment, and a primer treatment in order to improve the adhesiveness with the foamed elastic layer 3.

The length of the shaft body 2 in the axial direction is not particularly limited, and may be appropriately adjusted according to the form of the image forming apparatus to be installed. For example, when the printing target is A4 size, the length of the shaft body 2 in the axial direction is preferably 250 mm or more and 320 mm or less, and more preferably 260 mm or more and 310 mm or less. Further, the diameter of the shaft body 2 (diameter of the circumscribed circle) is not particularly limited, and may be appropriately adjusted according to the form of the image forming apparatus to be installed. For example, the outer diameter (diameter of the circumscribed circle) of the shaft body 2 is preferably 4 mm or more and 14 mm or less, and more preferably 6 mm or more and 10 mm or less.

(Foam elastic layer)
The foamed elastic layer 3 is formed by foaming and vulcanizing a composition for a foamed elastic layer containing (A) a mirable type silicone rubber composition, (B) a vinyl group-containing silicone raw rubber, (C) a foaming agent and (D) a cross-linking agent. It is something that is made to.

The foamed elastic layer 3 has a loss coefficient tan δ measured at a frequency of 8 Hz, a temperature of 100 ° C., and a strain control of 5 μm in the dynamic viscoelasticity measurement of 0.035 or less, preferably 0.025 or less.
The loss coefficient tan δ is a rubber containing (A) a mirable type silicone rubber composition, (B) a vinyl group-containing silicone raw rubber, and (D) a cross-linking agent obtained by removing (C) a foaming agent from the composition for a foamed elastic layer. It is the measurement of the cured product of the composition. That is, by using a rubber composition having a tan δ of 0.035 or less as the rubber material of the foamed elastic layer, a foamed elastic layer that does not easily deteriorate due to fatigue can be obtained, and as a result, a highly durable sponge roller can be obtained. Obtainable.
Hereinafter, the components of the composition for the foamed elastic layer will be described.

(A) Mirable Type Silicone Rubber Composition As the mirable type silicone rubber composition, an addition-curing type mirable type silicone rubber composition is preferable. The addition-curing type miraculous silicone rubber composition preferably contains, for example, at least (a) an organopolysiloxane and (b) a filler.

(A) Organopolysiloxane (a) The organopolysiloxane is represented by the following average composition formula (1).
R _a SiO _{(4-a) / 2} (1)
(In the formula, R is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms of the same or different from each other, preferably 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms. A is 1.5. It is a positive number in the range of ~ 2.8, preferably 1.8 to 2.5, more preferably 1.95 to 2.05, and even more preferably 1.98 to 2.01.)
R ¹ _n SiO _{(4-n) / 2} ... (1)
In the formula (1), n represents a positive number of 1.95 or more and 2.05 or less. Further, R ¹ indicates a substituted or unsubstituted monovalent hydrocarbon group which may be the same or different. The number of carbon atoms of the hydrocarbon group is preferably 1 or more and 12 or less, and more preferably 1 or more and 8 or less.

Examples of R ¹ include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group and a dodecyl group, a cycloalkyl group such as a cyclohexyl group, a vinyl group, an allyl group, a butenyl group and a hexenyl group. Examples thereof include an aryl group such as an alkenyl group, a phenyl group and a trill group, and an aralkyl group such as a β-phenylpropyl group. Further, R ¹ may be a group in which a part or all of the hydrogen atoms of these hydrocarbon groups are substituted with a substituent. The substituent may be, for example, a halogen atom, a cyano group, or the like. Examples of the hydrocarbon group having a substituent include a chloromethyl group, a trifluoropropyl group, a cyanoethyl group and the like.

(A) The organopolysiloxane has a molecular chain terminal such as a trialkylsilyl group such as a trimethylsilyl group, a dialkylaralkylsilyl group such as a dimethylvinylsilyl group, a dialkylhydroxysilyl group such as a dimethylhydroxysilyl group, or a trivinylsilyl group. It is preferably sealed with a trialal kill silyl group or the like.

(A) The organopolysiloxane preferably has two or more alkenyl groups in the molecule. (A) organopolysiloxane, 0.001 mol% or more of ^{R 1} 5 mol% or less (more preferably at least 0.01 mol% 0.5 mol%) preferably has an alkenyl group. (A) As the alkenyl group contained in the organopolysiloxane, a vinyl group is particularly preferable.

(A) The organopolysiloxane is obtained by, for example, co-hydrolyzing and condensing one or more of organohalosilanes, or ring-opening polymerization of a cyclic polysiloxane such as a trimer or tetramer of siloxane. Can be obtained by (A) The organopolysiloxane may be basically a linear diorganopolysiloxane and may be partially branched. Further, the (A) organopolysiloxane may be a mixture of two or more kinds having different molecular structures.

The kinematic viscosity of the (A) organopolysiloxane at 25 ° C. is preferably 100 cSt or more, and more preferably 100,000 cSt or more and 10,000,000 cSt or less.
Further, the degree of polymerization of (A) organopolysiloxane is preferably, for example, 100 or more, and more preferably 3000 or more and 10000 or less.

(B) Filler (b) Examples of the filler include silica-based fillers. Examples of the silica-based filler include fumes silica, precipitated silica and the like.

As the silica-based filler, a surface-treated silica-based filler surface-treated with the silane coupling agent ^{represented by R 2} Si (OR ³ ) _{3 can be preferably used.} Here, R ² may be a group having a vinyl group or an amino group, and may be, for example, a glycidyl group, a vinyl group, an aminopropyl group, a methacryoxy group, an N-phenylaminopropyl group, a mercapto group or the like. R ³ may be an alkyl group, for example, a methyl group, an ethyl group, or the like. The silane coupling agent can be easily obtained, for example, under the trade names "KBM1003" and "KBE402" manufactured by Shin-Etsu Chemical Co., Ltd. The surface-treated silica-based filler can be obtained by treating the surface of the silica-based filler with a silane coupling agent according to a conventional method. As the surface-treated silica-based filler, a commercially available product may be used, for example, J.A. M. Examples thereof include the product name "Zeothix 95" manufactured by HUBER Co., Ltd.

The blending amount of the silica-based filler is preferably 11 parts by mass or more and 39 parts by mass or less, and more preferably 15 parts by mass or more and 35 parts by mass or less with respect to 100 parts by mass of (A) organopolysiloxane. The average particle size of the silica-based filler is preferably 1 μm or more and 80 μm or less, and more preferably 2 μm or more and 40 μm or less. The average particle size of the silica-based filler can be measured as the median diameter using a particle size distribution measuring device by a laser light diffraction method.

The mirabable silicone rubber in the present invention is, for example, KE-571-U, KE-1571-U, KE-951-U, KE-541-U, KE-551-U, KE manufactured by Shin-Etsu Chemical Co., Ltd. -561-U, KE-961T-U, KE-1541-U, KE-1551-U, KE-941-U, KE-971T-U and the like can be used. Further, as the mirable type silicone rubber containing the conductivity-imparting agent, KE-87C-40PU or the like can be used.

(B) Vinyl group-containing silicone raw rubber (B) The vinyl group-containing silicone raw rubber contains at least one vinyl group in one molecule, and even if one molecule contains two vinyl groups. good.
Examples of the vinyl group-containing silicone raw rubber include vinyl methyl silicone raw rubber, phenylmethyl silicone raw rubber, and fluorosilicone raw rubber.

The blending amount ratio of (A) the addition-curing type mirable type silicone rubber composition and (B) the vinyl group-containing raw silicone rubber is preferably in the range of 50:50 to 80:20, and is preferably 60:40 to 70: It is more preferably in the range of 30.

(C) Foaming Agent As the foaming agent, a known foaming agent used for forming the foaming elastic layer 3 can be used. For example, chemical foaming agents and unexpanded microballoons can be used. In the case of a chemical foaming agent, examples of the inorganic foaming agent include sodium bicarbonate, ammonium carbonate and the like, and examples of the organic foaming agent include organic azo compounds such as a diazoamino derivative, an azonitrile derivative and an azodicarboxylic acid derivative. Among the organic azo compounds, azodicarboxylic acid amide, azobis-isobutyronitrile and the like are preferably used. In particular, azobis-isobutyronitrile can be preferably used.

As the unexpanded microballoon, a resin microballoon can be mentioned. As the resin microballoon, one using a thermoplastic resin for the outer shell is preferably used. Examples of the thermoplastic resin constituting the outer shell include vinylidene chloride / acrylonitrile copolymer, methyl methacrylate / acrylonitrile copolymer, and metaacrylonitrile / acrylonitrile copolymer. It is preferable to use a resin microballoon in which the softening temperature of the resin to be the outer shell is within an appropriate range according to the curing temperature of the silicone rubber. Further, examples of the contained evaporative substance include hydrocarbons such as butane and isobutane.
The average particle size of the unexpanded microballoon is preferably 5 μm or more and 50 μm or less, and more preferably 5 μm or more and 25 μm or less.

An unexpanded microballoon can also be used as the foaming agent. The uninflated microballoons suitable for the present invention are commercially available as "Matsumoto Microsphere F Series" (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.), "Expansel Series" (manufactured by Expansel Co., Ltd.) and the like. The unexpanded resin microballoon suitable for the present invention is selected from resin microballoons having a function of expanding at a temperature higher than the decomposition temperature of the chemical foaming agent used to form the elastic layer.
The blending amount of the foaming agent shall be 0.5% by mass or more and 6% by mass or less from the viewpoint of obtaining a cell having a uniform size while having a low specific gravity with respect to 100 parts by mass of the composition for an elastic foam layer. Is preferable.

(D) Cross-linking agent Examples of the cross-linking agent include an addition reaction cross-linking agent and an organic peroxide cross-linking agent.
As the addition reaction cross-linking agent, for example, organohydrogenpolysiloxane known as an addition reaction type cross-linking agent having two or more SiH groups (SiH bonds) in one molecule is preferably mentioned. The addition reaction cross-linking agent can be used alone or in combination of two or more.
The blending amount of the addition reaction cross-linking agent is usually 0.1 part by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the composition for foam elastic layer.

When an addition reaction cross-linking agent is used, the organic peroxide cross-linking agent can be used alone to cross-link the miraculous silicone rubber, but when used in combination as an auxiliary cross-linking agent for the addition reaction cross-linking agent, a toner supply roller obtained can be obtained. Physical properties such as strength and strain can be further improved. Examples of the organic peroxide cross-linking agent include benzoyl peroxide, bis-2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, and 2,5-dimethyl-2,5-bis. Examples thereof include (t-butylperoxy) hexane.
The blending amount of the organic peroxide cross-linking agent is usually 0.1 part by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the composition for foam elastic layer. The organic peroxide cross-linking agent may be used alone or in combination of two or more.

The addition reaction cross-linking agent is preferably used in combination with an addition reaction catalyst. Addition reaction catalysts are platinum black, secondary platinum chloride, platinum chloride acid, reaction products of platinum chloride acid and monohydric alcohol, complexes of platinum chloride acid and olefins, platinum bisacetoacetate, palladium-based catalysts, rhodium-based catalysts. And so on. The blending amount of this addition reaction catalyst can be the amount of the catalyst.

In addition to the above, the composition for the foamed elastic layer may further contain additives. Additives include, for example, conductive materials, auxiliary agents (chain extenders, cross-linking agents, etc.), catalysts, dispersants, antioxidants, antioxidants, pigments, colorants, processing aids, softeners, plasticizers, etc. Examples thereof include emulsifiers, heat resistance improvers, flame retardancy improvers, acid receiving agents, heat conductivity improvers, mold release agents, solvents and the like.

The foamed elastic layer 3 is formed on the outer peripheral surface of the shaft body 2 by performing heat curing and molding simultaneously or continuously by a known molding method. The method for curing the rubber composition may be any method as long as the heat required for curing the rubber composition can be applied. Further, the molding method of the foamed elastic layer 3 is not particularly limited, such as continuous vulcanization by extrusion molding, pressing, and mold molding by injection. For example, extrusion molding or the like can be selected. Further, the foamed elastic layer 3 formed on the shaft body 2 may be ground or polished.

The heating temperature for vulcanizing the foamed elastic layer composition is preferably 100 ° C. or higher and 500 ° C. or lower, and more preferably 120 ° C. or higher and 300 ° C. or lower. The heating time is preferably several seconds or more and 1 hour or less, and more preferably 10 seconds or more and 35 minutes or less. Further, if necessary, secondary vulcanization may be carried out. Further, the rubber composition can be easily foamed and cured by a known method to easily form the foamed elastic layer 3 having bubbles.

The hardness of the foamed elastic layer 3 (ascar C hardness) is preferably 15 degrees or more and 40 degrees or less. In such a low hardness foam elastic layer, it is effective to use a rubber material exhibiting tan δ as described above.

The sponge roller of the present invention is suitable for a pressure roller or a fixing roller of various image forming devices using an electrophotographic method.
Although the present invention has been described above with reference to the embodiments, it goes without saying that the technical scope of the present invention is not limited to the scope of the invention described in the above embodiments. It will be apparent to those skilled in the art that improvements can be made. It is also clear from the description of the claims that the invention with such changes or improvements may be included in the technical scope of the present invention.

Hereinafter, the present invention will be described in detail with reference to examples.
[Example 1]
(Preparation of composition for foamed elastic layer)
A composition for a foamed elastic layer was prepared with the following materials.
(A) Additive-curing type mirable type silicone rubber composition (X-30-4037U, manufactured by Shin-Etsu Chemical Co., Ltd.) 80 parts by mass (B) Vinyl group-containing silicone raw rubber (KE-77VB, manufactured by Shin-Etsu Chemical Co., Ltd.)
20 parts by mass (C) Chemical foaming agent 5 parts by mass (D) Cross-linking agent 3 parts by mass

(Formation of primer layer)
The shaft body (made by SUM22, diameter 10 mm, length 275 mm) subjected to electroless nickel plating is washed with ethanol, and a silicone-based primer (trade name "Primer No. 16", manufactured by Shin-Etsu Chemical Co., Ltd.) is used on the surface thereof. ) Was applied. The primer-treated shaft was fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the outer peripheral surface of the shaft.

(Formation of foamed elastic layer)
Next, the shaft body on which the primer layer was formed and the composition for the foamed elastic layer were integrally separated by an extrusion molding machine, and the above mixture was heated at 250 ° C. for 20 minutes using an infrared heating furnace (IR furnace). The foam roller original body was prepared by secondary vulcanization and then secondary vulcanization at 210 ° C. for 10 hours in a hot air drying oven. The circumferential surface of the foam roller original body was polished at high speed with a metal grindstone by a polishing machine manufactured by Mizuguchi Seisakusho Co., Ltd. to produce a sponge roller roller having an outer diameter of 32 mm.

[Examples 2 and 3 and Comparative Examples 1 to 3]
It was produced in the same manner as in Example 1 except that the type and composition of the vinyl group-containing silicone raw rubber were changed as shown in Table 1.

[evaluation]
The following durability evaluations were carried out for the above-mentioned Examples and Comparative Examples. The evaluation results are shown in Table 1.
(Amount of change in hardness)
As a durability evaluation, the amount of change in hardness was measured by the following evaluation method.
A roller having a product diameter of φ32 mm was manufactured using a shaft diameter of φ22.0 mm. The roller was compressed and fixed to a metal roller having a diameter of 40.0 mm, equivalent to 35% of the rubber thickness. In that state, it was rotated for 200 hours while giving a temperature of 180 ° C. The hardness before the start of measurement (0 hours) is set to 0, and the hardness after 100 hours of rotation and after 200 hours of rotation is measured with an ASKER rubber hardness tester C type (manufactured by Polymer Meter Co., Ltd.) at a measurement load of 9.8 N. did. The amount of change in hardness with time is shown in Table 2, and the graph is shown in FIG.

(Loss coefficient tanδ)
Next, in the above Examples and Comparative Examples, a composition for a foamed elastic layer to which a foaming agent was not added was prepared and vulcanized to prepare a sample having a length of 20 mm × a width of 5 mm × a thickness of 2 mm, and viscoelasticity was prepared. The loss coefficient tan δ was measured with a spectrum meter (manufactured by Rheology Co., Ltd.). The measurement conditions are as follows.
<Measurement conditions>
Using a dynamic sticky bullet measuring machine (trade name "Pheogel-E4000", UBM Co., Ltd.), frequency 8 Hz, start temperature 30 ° C, end temperature 100 ° C, temperature rise rate 5 ° C / min, strain control 5 μm, distance between chucks. It was measured at 10 mm.

As shown in Tables 1 and 2, the sponge roller of the present invention has a tan δ of 0.035 or less and a hardness of 0.035 or less by incorporating a silicone raw rubber having a vinyl group in the side chain in the composition for a foamed elastic layer. The amount of change (degree) can be suppressed to within -3.
On the other hand, in Comparative Example 3 in which the side chain contains a silicone raw rubber containing no vinyl group, the tan δ and the amount of change in hardness are larger than those in the examples, and Comparative Example 1 and Comparative Example 1 in which only the mirable type silicone composition contains no other silicone raw rubber. It can be seen that in No. 2, the tan δ and the amount of change in hardness are large.

1 Sponge roller 2 Shaft body 3 Foam elastic layer

Claims (3)

A sponge roller provided with a shaft body and a foamed elastic layer formed on the outer periphery of the shaft body.
The foamed elastic layer is formed by foaming and vulcanizing a composition for a foamed elastic layer containing a mirable type silicone rubber composition, a vinyl group-containing silicone raw rubber, a foaming agent, and a cross-linking agent.
A sponge roller having a loss coefficient tan δ of 0.035 or less under the following measurement conditions of a cured product of a rubber composition obtained by removing the foaming agent from the composition for an elastic foam layer.
<Measurement conditions>
Frequency 8Hz, temperature 100 ℃, strain control 5μm The sponge roller according to claim 1, wherein the Asker C hardness of the foamed elastic layer is 15 degrees or more and 40 degrees or less. The sponge roller according to claim 1 or 2, which is a pressure roller.

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