Sponge roller

Abstract

The present invention is a sponge roller (1) provided with a shaft body (2) and a foamed elastic layer (3) provided on the outer periphery of the shaft body (2), the foamed elastic layer (3) having an average cell diameter of 20-100 [mu] m, and the foamed elastic layer (3) having an average cell diameter of 20-100 [mu] m. The variance of the slope value of an approximate straight line in a load-displacement curve of a rebound load measurement result obtained by a predetermined calculation method is 0.005 or less.

Description

Technical Field

[0001] This invention relates to a sponge roller. Background Technology

[0002] Various image forming devices utilizing electrophotographic methods are employed in printers, copiers, fax machines, and multifunction printers, including laser printers and video printers. These electrophotographic image forming devices include various printing rollers such as cleaning rollers, charged rollers, developing rollers, transfer rollers, secondary transfer rollers, pressure rollers, paper feed rollers, and fixing rollers, which have a shaft and an elastic layer formed on their outer circumference.

[0003] The fixing unit in the image forming apparatus employs a hot roller fixing method. In hot roller fixing, a heating roller (fixing roller) and a pressure roller are typically used as a basic pair. The toner image is hot-pressed and fixed onto the recording material (transfer sheet, fax paper, printing paper, etc.) by guiding the recording material carrying the toner image into the pressing and clamping part of the roller pair. The fixing roller or pressure roller used in the fixing unit utilizes a foamed elastic layer (sponge layer) to adjust to a suitable clamping pressure.

[0004] Foamed elastic layers are generally formed by vulcanizing and foaming a compounded silicone rubber containing organopolysiloxanes and fillers. Fixing or pressure rollers with foamed elastic layers are installed in a pressed state and function through continuous or intermittent rotation; therefore, they are susceptible to loads caused by heat or friction, requiring high durability. To improve durability, for example, Patent Document 1 discloses a sponge roller that contains a chemical foaming agent and expanded resin balls that expand at higher temperatures than the chemical foaming agent in its foamed elastic layer.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-36611 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The foamed elastic layer is formed, for example, by extrusion molding. However, in the technology described in Patent Document 1, after vulcanization, the size and shape of the pores in the foamed elastic layer differ near the shaft and on the surface of the foamed elastic layer. Specifically, the pores near the shaft are elliptical in shape, while those on the surface are nearly circular. In this type of foamed elastic layer, the following problem exists: stress concentrates in a portion of the foamed elastic layer, reducing durability.

[0010] The present invention was made in view of the above circumstances, and its object is to provide a sponge roller with high durability.

[0011] Technical means to solve the problem

[0012] The inventors discovered that by uniformly forming the hardness of the foamed elastic layer in the thickness direction, stress concentration can be mitigated, thereby obtaining a sponge roller with high durability, thus completing the present invention.

[0013] That is, the present invention is a sponge roller, including a shaft and a foamed elastic layer disposed on the outer periphery of the shaft. In the sponge roller, the average cell diameter of the foamed elastic layer is more than 20 μm and less than 100 μm. In the foamed elastic layer, the variance of the slope value of the approximate straight line in the load-displacement curve of the rebound load measurement result obtained by the following calculation method is less than 0.005.

[0014] <Calculation Method>

[0015] 1. In the region more than 10 mm away from both ends of the foamed elastic layer along the axial direction, cut two incisions at intervals of 15 mm, and then cut parallel to the axial direction at a distance of 10 mm from the curved surface to make a semi-cylindrical sample.

[0016] 2. On the surface of the semi-cylindrical sample parallel to the radial direction, use a micro load tester to measure the rebound load at a total of five points in a cross shape along the short and long sides until the maximum load of 5 N is reached.

[0017] 3. Calculate the slopes X1, X2, X3, X4, and X5 of the approximate straight lines of the load-displacement curves at the five points.

[0018] 4. Calculate the average value A of the five slopes X1 to X5.

[0019] 5. Calculate the variance according to the following formula (1).

[0020] [Number 1]

[0021] Equation (1)

[0022] Preferably, the foamed elastic layer is formed from a foamed elastic layer composition comprising a compounded silicone rubber composition, a vinyl-containing silicone raw rubber, a foaming agent, and a crosslinking agent, wherein only expanded resin balls are used as the foaming agent.

[0023] Preferably, the foamed elastic layer is formed by extrusion molding.

[0024] Preferably, the mass of the expanded resin balls in the composition for the foamed elastic layer is 5 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass of the composition for the foamed elastic layer.

[0025] Preferably, the expanded resin balls have a particle size of 20 μm or more and 100 μm or less.

[0026] The effects of the invention

[0027] This invention provides a highly durable sponge roller. Attached Figure Description

[0028] [ Figure 1 [Illustration 1] is a perspective view showing one embodiment of the sponge roller of the present invention.

[0029] [ Figure 2 [ ] is a graph showing the method for measuring the hardness of foamed elastic layers.

[0030] [ Figure 3 [] is a graph representing an approximate straight line of the load-displacement curve for Example 1 (n=1).

[0031] [ Figure 4 [] is a graph representing an approximate straight line of the load-displacement curve for Comparative Example 1 (n=1). Detailed Implementation

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0033] [Sponge Roller]

[0034] like Figure 1 As shown, the sponge roller of the present invention includes a shaft 2 and a foamed elastic layer 3 disposed on the outer periphery of the shaft 2. Moreover, the foamed elastic layer 3 is formed of a foamed elastic layer composition, which includes a compounded silicone rubber composition, a vinyl-containing silicone raw rubber, a foaming agent, and a crosslinking agent. As the foaming agent, only expanded resin balls are used.

[0035] That is, the sponge roller 1 of the present invention has high durability because the rebound load is uniform in the thickness direction of the foamed elastic layer 3, thus applying stress evenly.

[0036] The structure of the sponge roller will be described below.

[0037] <Spindle>

[0038] The shaft 2 is preferably a shaft with conductive properties, as used in existing known sponge rollers. The shaft 2 is preferably, for example, made of at least one metal selected from the group consisting of iron, aluminum, stainless steel, and brass. Furthermore, this type of shaft 2 is generally also known as a "core".

[0039] The shaft body 2 may also 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 containing the insulating resin and a plating layer disposed on the core. Such a shaft body 2 can be obtained, for example, by plating the core containing the insulating resin and making it conductive.

[0040] To obtain good electrical conductivity, the shaft 2 is preferably a core.

[0041] The shape of the shaft 2 is preferably rod-shaped or tubular. The cross-sectional shape of the shaft 2 can be circular, elliptical, or non-circular, such as polygonal. The outer peripheral surface of the shaft 2 can be treated with cleaning, degreasing, primer, etc.

[0042] The axial length of the shaft 2 is not particularly limited and can be adjusted appropriately according to the shape of the image forming apparatus. In addition, the diameter (diameter of the circumscribed circle) of the shaft 2 is also not particularly limited and can be adjusted appropriately according to the shape of the image forming apparatus.

[0043] <Foamed Elastic Layer>

[0044] Foamed elastic layer 3 is formed by vulcanizing a foamed elastic layer containing (A) a compounded silicone rubber composition, (B) a vinyl-containing silicone raw rubber, (C) an expanded resin ball, and (D) a crosslinking agent.

[0045] The composition of the foamed elastic layer is described below.

[0046] (A) Compound silicone rubber composition

[0047] As a compounded silicone rubber composition, an addition-curing compounded silicone rubber composition is preferred. An addition-curing compounded silicone rubber composition is preferably, for example, containing at least (a) an organopolysiloxane and (b) a filler.

[0048] (a) Organopolysiloxane

[0049] (a) The organopolysiloxane is represented by the following average composition formula (1).

[0050] R 1 n SiO (4-n) / 2 …(1)

[0051] In equation (1), n ​​represents a positive number greater than 1.95 and less than 2.05. Additionally, R... 1 This refers to a monovalent hydrocarbon group that may be the same or different, substituted or unsubstituted. The number of carbon atoms in the hydrocarbon group is preferably 1 or more and 12 or less, more preferably 1 or more and 8 or less.

[0052] As R 1 Examples include: alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl; cycloalkyl groups such as cyclohexyl; alkenyl groups such as vinyl, allyl, butenyl, and hexenyl; aryl groups such as phenyl and tolyl; and aralkyl groups such as β-phenylpropyl. Additionally, R... 1 These can be groups in which some or all of the hydrogen atoms of these hydrocarbon groups are replaced by substituents. Substituents can be, for example, halogen atoms, cyano groups, etc. Examples of hydrocarbon groups with substituents include: chloromethyl, trifluoropropyl, cyanoethyl, etc.

[0053] (a) The organopolysiloxane is preferably end-capped by trialkylsilyl such as trimethylsilyl, dialkylarylsilyl such as dimethylvinylsilyl, dialkylhydroxysilyl such as dimethylhydroxysilyl, trialkylaryl such as trivinylsilyl, etc.

[0054] (a) The organopolysiloxane is preferably one having two or more alkenyl groups in its molecule. (a) The organopolysiloxane is preferably one having two or more alkenyl groups in its R... 1 It contains 0.001 mol% or more and 5 mol% or less (more preferably 0.01 mol% or more and 0.5 mol% or less) of an alkenyl group. As the alkenyl group contained in (a) the organopolysiloxane, vinyl groups are particularly preferred.

[0055] (a) Organopolysiloxanes can be obtained, for example, by co-hydrolytic condensation of one or more organohalosilanes, or by ring-opening polymerization of cyclic polysiloxanes such as trimers or tetramers of siloxanes. (a) Organopolysiloxanes can be substantially linear diorganopolysiloxanes, or partially branched. Additionally, (a) organopolysiloxanes can also be mixtures of two or more molecules with different structures.

[0056] (a) The preferred dynamic viscosity of the organopolysiloxane at 25°C is 1×10⁻⁶. -4 m 2 / s or more, preferably 1×10 -1 m 2 / s or more and 1×10 1 m 2 / s or less.

[0057] In addition, (a) the degree of polymerization of the organopolysiloxane is preferably 100 or more, more preferably 3000 or more and 10000 or less.

[0058] (b) Filler material

[0059] As filler material (b), examples include silica-based fillers. Examples of silica-based fillers include fumed silica and settled silica.

[0060] As a silica-based filler, R can be preferably used. 2 Si(OR 3 )3 represents a surface-treated silica-based filler containing a silane coupling agent. Here, R... 2 It can be a group having a vinyl or amino group, such as glycidyl, vinyl, aminopropyl, methacryloyloxy, N-phenylaminopropyl, mercapto, etc. R 3 It can be an alkyl group, such as methyl or ethyl. Silane coupling agents are readily available, for example, in the form of trade names such as "KBM1003" and "KBE402" manufactured by Shin-Etsu Chemical Industry Co., Ltd. Surface-treated silica-based fillers can be obtained by treating the surface of silica-based fillers with a silane coupling agent using conventional methods. Commercially available products can be used as surface-treated silica-based fillers, such as "Zeothix 95" manufactured by JMHUBER Co., Ltd.

[0061] The amount of silica-based filler mixed with (a) organopolysiloxane is preferably 11 parts by mass or more and 39 parts by mass or less, more preferably 15 parts by mass or more and 35 parts by mass or less, relative to 100 parts by mass. Furthermore, the average particle size of the silica-based filler is preferably 1 μm or more and 80 μm or less, more preferably 2 μm or more and 40 μm or less. In addition, the average particle size of the silica-based filler can be measured as median particle size using a particle size distribution measuring device based on laser diffraction.

[0062] (B) Vinyl-containing silicone raw rubber

[0063] As (B) a vinyl-containing silicone raw rubber, it contains at least one vinyl group in one molecule, or two vinyl groups in one molecule.

[0064] Examples of vinyl-containing silicone raw rubbers include: vinyl methyl silicone raw rubber, phenyl methyl silicone raw rubber, and fluorosilicone raw rubber.

[0065] The preferred mass ratio of (A) addition-curing compounded silicone rubber composition to (B) vinyl-containing raw silicone rubber is in the range of 50:50 to 80:20, more preferably in the range of 60:40 to 70:30.

[0066] (C) Expanded resin balls

[0067] The composition for the foamed elastic layer contains only expanded resin balls as a foaming agent. By using expanded resin balls as a foaming agent, fine cells can be uniformly formed throughout the foamed elastic layer, thus creating a sponge roller with high durability.

[0068] As expanded resin balls, examples include those with calcium carbonate powder wrapped around their shells, known as composite-type expanded resin balls. Expanded resin balls suitable for this invention are commercially available in the form of "Matsumoto Microsphere MFL series" (manufactured by Matsumoto Oils & Fats Pharmaceutical Co., Ltd.) and "Expancel DE grade" (manufactured by Fillite Co., Ltd., Japan).

[0069] The average particle size of the expanded resin balls is preferably 20 μm or more and 100 μm or less, more preferably 40 μm or more and 80 μm or less. By making the average particle size of the expanded resin balls within this range, fine pores can be uniformly formed.

[0070] The expanded resin balls are preferably contained in a mixture of expanded resin balls and vinyl-containing silicone raw rubber in a mass ratio of 1:4 or more and 1:6 or less.

[0071] The mass of the expanded resin balls is preferably 5 parts or more and 30 parts or less per 100 parts by mass of the composition for the foamed elastic layer, more preferably 5 parts or more and 25 parts or less per 100 parts by mass.

[0072] (D) Crosslinking agent

[0073] The composition for the foamed elastic layer contains a crosslinking agent. Examples of crosslinking agents include addition reaction crosslinking agents and organic peroxide crosslinking agents.

[0074] As the addition reaction crosslinking agent, examples preferably include organohydrogen polysiloxanes known as addition reaction type crosslinking agents having two or more SiH groups (SiH bonds) in one molecule. The addition reaction crosslinking agent can be used alone or in combination of two or more.

[0075] The amount of the addition reaction crosslinking agent is usually 0.1 parts by mass and 7 parts by mass or less per 100 parts by mass of the composition for the foamed elastic layer.

[0076] When using addition reaction crosslinking agents, organic peroxide crosslinking agents can also crosslink compounded silicone rubber on their own. However, when used as an auxiliary crosslinking agent in conjunction with addition reaction crosslinking agents, the strength, strain, and other physical properties of the obtained toner supply roller can be further improved. Examples of organic peroxide crosslinking agents include: benzoyl peroxide, bis-2,4-dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butyl peroxide)hexane.

[0077] The amount of organic peroxide crosslinking agent is typically 0.1 parts by weight or more and 7 parts by weight or less per 100 parts by weight of the composition for the foamed elastic layer. Organic peroxide crosslinking agents can be used alone or in combination of two or more.

[0078] The crosslinking agent for the addition reaction is preferably used in conjunction with the addition reaction catalyst. Examples of addition reaction catalysts include: platinum black, platinum chloride, chloroplatinic acid, the reaction product of chloroplatinic acid with a monovalent alcohol, the complex of chloroplatinic acid with an olefin, platinum diacetate, palladium-based catalysts, and rhodium-based catalysts. Furthermore, the amount of this addition reaction catalyst can be set as the catalyst amount.

[0079] (Other ingredients)

[0080] The composition for foamed elastic layers may also contain various additives. Examples of such additives include: conductive agents, chain extenders, dispersants, anti-aging agents, and antioxidants. Examples of fillers other than silica-based fillers include: glass beads, pigments, colorants, processing aids, softeners, plasticizers, emulsifiers, heat resistance improvers, flame retardant improvers, acid absorbers, thermal conductivity improvers, release agents, and solvents. These additives may be commonly used or specifically designed for particular applications.

[0081] The compounded silicone rubber used in this invention can be, for example, KE-571-U, KE-1571-U, KE-951-U, KE-541-U, KE-551-U, KE-561-U, KE-961T-U, KE-1541-U, KE-1551-U, KE-941-U, KE-971T-U, etc., manufactured by Shin-Etsu Chemical Industry Co., Ltd. Additionally, KE-87C-40PU, etc., can be used as a compounded silicone rubber containing a conductive agent.

[0082] The foamed elastic layer 3 is formed on the outer peripheral surface of the shaft 2 by heating, hardening and forming simultaneously or continuously using known forming methods.

[0083] The foamed elastic layer 3 can be formed by continuous vulcanization using extrusion molding, compression molding, injection molding, etc., and there are no particular restrictions. For example, extrusion molding can be selected.

[0084] The curing method for the foamed elastic layer composition is any method that applies the required heat for curing (curing) the foamed elastic layer composition. The heating temperature for curing the foamed elastic layer composition is preferably 100°C or higher and 500°C or lower, 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, more preferably 10 seconds or more and 35 minutes or less. Furthermore, secondary curing may be performed if necessary.

[0085] (The variance of the slope of the approximate straight line in the load-displacement curve of the rebound load measurement results in the foamed elastic layer)

[0086] The variance of the slope of the approximate straight line in the load-displacement curve of the rebound load measurement results in the foamed elastic layer 3 can be determined using the following method (refer to...). Figure 2 )

[0087] 1. In the region at least 10 mm inside both ends (31, 32) of the foamed elastic layer 3 along the axial (Z direction), cuts are made at two locations (A, B) at intervals of 15 mm (t). Figure 2 (a) A semi-cylindrical sample 33 is made by cutting parallel to the axial direction with a distance L of 10 mm from the curved surface 33a. Figure 2 (b)).

[0088] 2. On the surface (XY plane) 33b of the semi-cylindrical sample 33, parallel to the radial direction (X direction or Y direction), use a micro-load measuring device to measure the rebound load at a total of five points (a, b, c, d, e) in a cross shape along the short side (X direction) and long side (Y direction) until the maximum load of 5 N is reached. Figure 2 (c)).

[0089] As a micro load measuring instrument, the product name "MODEL-1305VR" (manufactured by Aikoh Engineering Co., Ltd.) can be used.

[0090] The variance is calculated based on the rebound load measured as described above, in the following manner.

[0091] 3. Calculate the slopes X1, X2, X3, X4, and X5 of the approximate straight lines of the load-displacement curves at the five points.

[0092] 4. Calculate the average value A of the five slopes X1 to X5.

[0093] 5. Calculate the variance according to the following formula (1).

[0094] [Number 2]

[0095] Equation (1)

[0096] In the foamed elastic layer 3 of the sponge roller 1 of the present invention, the variance calculated by the above calculation method is 0.005 or less. The variance is preferably 0.003 or less, and more preferably 0.002 or less.

[0097] Since the rebound load of the foamed elastic layer 3 is measured from the XY plane of the semi-cylindrical sample toward the depth direction as shown in the measurement method, the variance of this rebound load being 0.005 or less means that the rebound load of the foamed elastic layer 3 is uniform in the thickness direction of the foamed elastic layer 3. The sponge roller 1 of the present invention, including this type of foamed elastic layer 3, has high durability because stress is applied evenly.

[0098] (Rebound load of the foamed elastic layer)

[0099] The rebound load of the foamed elastic layer 3 can be measured using the aforementioned program 1 and program 2. At any of the five points, the slope X1 to slope X5 of the approximate straight line of the load-displacement curve is preferably 0.5 or more and 3.0 or less, more preferably 0.8 or more and 1.8 or less, and even more preferably 1.0 or more and 1.6 or less.

[0100] (Hardness of the foamed elastic layer)

[0101] The A hardness of the foamed elastic layer 3 is preferably 10 or more and 30 or less in both the surface and depth directions, and more preferably 15 or more and 22 or less. Regarding the A hardness of the foamed elastic layer 3, the five points can be measured using an ASKER miniature rubber hardness tester MD-1capa A type (manufactured by Polymer Instruments Co., Ltd.), similar to procedures 1 and 2 of the method for measuring the rebound load.

[0102] (Average cell diameter of the foamed elastic layer)

[0103] The average pore diameter of the foamed elastic layer 3 is 20 μm or more and 100 μm or less, preferably 40 μm or more and 80 μm or less, and more preferably 50 μm or more and 70 μm or less. By making the average pore diameter of the foamed elastic layer 3 within the aforementioned range, it becomes a fine and uniform pore structure, thus mitigating stress concentration and obtaining a foamed elastic layer 3 with high durability.

[0104] The average cell diameter of the foamed elastic layer 3 can be determined using a PORESCAN (pore scan) testing machine for polyurethane foam-elastomers (trade name, manufactured by Goldlucke GmbH).

[0105] <Method for determining the average cell diameter of foamed elastic layers>

[0106] The average bubble diameter is determined using the following method within the region containing the five points (a, b, c, d, e).

[0107] 1. At each of the five points, within 6 mm 2Within the area, calculate the area A of more than 1000 bubbles and the diameter d of the circle.

[0108]

[0109] 2. Calculate the area-weighted average of the circle diameters and use it as the average bubble diameter L.

[0110]

[0111] <Other Structures>

[0112] A resin tube can be provided on the outer peripheral surface of the foamed elastic layer 3. Materials used for the resin tube include: polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, FEP (fluorinated ethylene propylene), PFA (perfluoroalkoxy), ETFE (ethylene tetrafluoride), PVDF (polyvinylidene fluoride), polyethylene terephthalate, polyamide, polyimide, polycarbonate, polystyrene, ABS (acrylonitrile butadiene styrene), polyurethane, etc. Among these, PFA is preferred.

[0113] Resin tubes can be manufactured using resin compositions produced by methods such as melt extrusion. Resin tubes can be installed using known methods such as pressurized insertion and depressurized insertion.

[0114] The sponge roller 1 of the present invention forms a foamed elastic layer 3 with uniform pores having an average pore diameter of 20 μm or more and 100 μm or less by using expanded resin balls with a particle size of 20 μm or more and 100 μm or less. The uniform pore size of the foamed elastic layer 3 reduces the amount of hardness reduction caused by prolonged use, resulting in high durability.

[0115] Example

[0116] The present invention will now be described in detail with reference to specific embodiments. However, the present invention is not limited to any of the embodiments shown below.

[0117] [Example 1]

[0118] The sponge roller of Example 1 was manufactured according to the following procedure.

[0119] (Formation of the primer layer)

[0120] The shaft (made by SUM23, 10 mm in diameter, 274.2 mm in length) that underwent electroless nickel plating was cleaned with ethanol, and a silicone-based primer (trade name "Primer No. 16", manufactured by Shin-Etsu Chemical Industry Co., Ltd.) was applied to its surface. After calcining the primer-treated shaft at 150°C for 10 minutes using a Geer oven, it was cooled at room temperature for more than 30 minutes, forming a primer layer on the outer circumference of the shaft.

[0121] (Formation of the foamed elastic layer)

[0122] First, a composition for foamed elastic layers was prepared.

[0123] -Composition for foamed elastic layers-

[0124] (A) 50 parts by weight of addition-curing compounded silicone rubber (KE-951-U, manufactured by Shin-Etsu Chemical Industry Co., Ltd.)

[0125] (B) Vinyl-containing silicone raw rubber (KE-77VBS, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 50 parts by weight 100 parts by weight

[0126] (C) 10 parts by weight of expanded resin spheres (Matsumoto Microsphere MFL series, manufactured by Matsumoto Oils & Fats Pharmaceutical Co., Ltd.)

[0127] (D) 3 parts by weight of crosslinking agent

[0128] Using the aforementioned foamed elastic layer composition, a foamed elastic layer is formed on the outer peripheral surface of a primer layer by extrusion molding. Furthermore, in the extrusion molding, the composition is heated at 250°C for 15 minutes using an infrared ray (IR) furnace, and then cured at 225°C for 7 hours using a Gear oven. Thus, a foamed elastic layer is formed on the outer peripheral surface of the primer layer.

[0129] The thickness of the foamed elastic layer is 10 mm.

[0130] The average cell diameter of the foamed elastic layer is 60.8 μm. The average cell diameter was measured using a polyurethane foam-elastomer testing machine, PORE SCAN (trade name, manufactured by Goldlucke GmbH).

[0131] The A hardness of the foamed elastic layer is 16.8. The A hardness was measured using an ASKER MD-1capa A miniature rubber hardness tester (manufactured by Polymer Instruments Co., Ltd.).

[0132] (Method for calculating the variance of the slope of the approximate straight line in the load-displacement curve of the rebound load measurement results of the foamed elastic layer)

[0133] The variance was determined using the following method (refer to...). Figure 2 The results are shown in Table 1.

[0134] <Calculation Method>

[0135] First, the rebound load of the foamed elastic layer 3 was measured according to procedures 1 and 2 below.

[0136] 1. In the region on the inner side of the foamed elastic layer 3 at a distance of more than 10 mm from both ends (31, 32) in the axial direction (Z direction), cut out two incisions (A, B) at intervals of 15 mm. Then cut parallel to the axial direction (Z direction) with a distance of 10 mm from the curved surface 33a to make a semi-cylindrical sample.

[0137] 2. On the surface 33b of the semi-cylindrical sample, which is parallel to the radial direction (X direction or Y direction), the rebound load at a total of five points in a cross shape along the short and long sides is measured using a micro load measuring device.

[0138] Next, calculate the variance of the rebound load according to the procedures in steps 3 to 5 below. Figure 3 and Figure 4 This represents an approximate straight line representing the load-displacement curve. Furthermore, Figure 3 Example 1-1 represents the n=1 sample of Example 1. Figure 4 Comparative Example 1-1 represents the sample with n=1 of Comparative Example 1.

[0139] 3. Calculate the slopes X1, X2, X3, X4, and X5 of the approximate straight lines of the load-displacement curves at the five points.

[0140] 4. Calculate the average value A of the five slopes X1 to X5.

[0141] 5. Calculate the variance according to the following formula (1).

[0142] [Number 3]

[0143] Equation (1)

[0144] The equipment and conditions used in the determination of rebound load are as follows.

[0145] (1) Micro load measuring instrument: MODEL-1305VR (manufactured by Aikoh Engineering Co., Ltd.)

[0146] (2) Amplifier for micro load measuring instrument: MODEL-1016BASIC (manufactured by Aikoh Engineering Co., Ltd.)

[0147] (3) Precision load displacement measuring instrument data collection system (data acquisition software: FS-301v, manufactured by Aikoh Engineering Co., Ltd.)

[0148] (4) Measure the shape of the terminal tip: round, φ2.5 mm

[0149] Next, the variance was calculated using the same method for other parts of the same sponge roller as in Example 1. The results are shown in Table 1 as n=2.

[0150] [Example 2]

[0151] The expanded resin balls (C) were set at 12 parts by weight, and the sponge roller was made in the same manner as in Example 1.

[0152] The average pore diameter of the foamed elastic layer in Example 2 is 58.3 μm.

[0153] For other parts of the same sponge roller as in Example 2, the slope and variance were calculated using the same method. The results are shown in Table 1 as n=2.

[0154] [Example 3]

[0155] The expanded resin balls (C) were set at 14 parts by weight, and the sponge roller was made in the same manner as in Example 1.

[0156] The average pore diameter of the foamed elastic layer in Example 3 is 57.1 μm.

[0157] For other parts of the same sponge roller as in Example 3, the slope and variance were calculated using the same method. The results are shown in Table 1 as n=2.

[0158] [Comparative Example 1]

[0159] As a foaming agent, 2 parts by weight of unexpanded microspheres (Matsumoto Microsphere F series, manufactured by Matsumoto Oils & Fats Pharmaceutical Co., Ltd.) and 2 parts by weight of chemical foaming agent were used instead of (C) expanded resin spheres. Otherwise, the sponge roller was made in the same manner as in Example 1.

[0160] For other parts of the same sponge roller as in Comparative Example 1, the slope and its variance were calculated using the same method. The results are shown in Table 1 as n=2.

[0161] [Comparative Example 2]

[0162] As a foaming agent, 3 parts by weight of unexpanded microspheres (Matsumoto Microsphere F series, manufactured by Matsumoto Oils & Fats Pharmaceutical Co., Ltd.) and 2 parts by weight of chemical foaming agent were used instead of (C) expanded resin spheres. Otherwise, the sponge roller was made in the same manner as in Example 1.

[0163] For other parts of the same sponge roller as in Comparative Example 2, the slope and its variance were calculated using the same method. The results are shown in Table 1 as n=2.

[0164] [Comparative Example 3]

[0165] As a foaming agent, 4 parts by weight of unexpanded microspheres (Matsumoto Microsphere F series, manufactured by Matsumoto Oils & Fats Pharmaceutical Co., Ltd.) and 2 parts by weight of chemical foaming agent were used instead of (C) expanded resin spheres. Otherwise, the sponge roller was made in the same manner as in Example 1.

[0166] For other parts of the same sponge roller as in Comparative Example 3, the slope and its variance were calculated using the same method. The results are shown in Table 1 as n=2.

[0167] [Table 1]

[0168]

[0169] Explanation of icon numbers

[0170] 1: Sponge roller

[0171] 2: Shaft

[0172] 3: Foamed elastic layer

[0173] 31, 32: (Ends of the foamed elastic layer)

[0174] 33: Semi-cylindrical sample

[0175] 33a: (The curved surface of a semi-cylindrical sample)

[0176] 33b: A plane parallel to (the radial direction of the semi-cylindrical sample).

Claims

1. A sponge roller, comprising a shaft and a foamed elastic layer disposed on the outer periphery of the shaft, wherein the sponge roller, The average pore diameter of the foamed elastic layer is greater than 20 μm and less than 100 μm. In the foamed elastic layer, the variance of the slope of the approximate straight line in the load-displacement curve of the rebound load measurement results obtained using the following calculation method is less than 0.

005. <Calculation Method> 1. In the region more than 10 mm away from both ends of the foamed elastic layer in the axial direction, cut two incisions at intervals of 15 mm, and then cut parallel to the axial direction at a distance of 10 mm from the curved surface to make a semi-cylindrical sample.

2. On the surface of the semi-cylindrical sample parallel to the radial direction, the rebound load at a total of five points in a cross shape along the short and long sides is measured using a micro load measuring device until the maximum load of 5 N is reached.

3. Calculate the slopes X1, X2, X3, X4, and X5 of the approximate straight line of the load-displacement curve at the five points; 4. Calculate the average value A of the five slopes X1 to X5; 5. Calculate the variance according to the following formula (1); [Number 1] Equation (1).

2. The sponge roller according to claim 1, wherein the foamed elastic layer is formed of a foamed elastic layer composition, the foamed elastic layer composition comprising a compounded silicone rubber composition, a vinyl-containing silicone raw rubber, a foaming agent, and a crosslinking agent. Only expanded resin balls are used as the foaming agent.

3. The sponge roller according to claim 1, wherein the foamed elastic layer is formed by extrusion molding.

4. The sponge roller according to claim 2, wherein the mass of the expanded resin balls in the foamed elastic layer composition is 5 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass of the foamed elastic layer composition.

5. The sponge roller according to claim 2, wherein the particle size of the expanded resin balls is 20 μm or more and 100 μm or less.

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