JP5745008B2 - Rubber roll for film - Google Patents

Description

  The present invention relates to a rubber roll for film.

  Films are thin-film artifacts made of polymer compounds as the main raw materials. Films for packaging, optics, photography and cinema, and films with specific functionality are widely used in various applications. It is used.

  Common film production methods include, for example, a stretching method, a calendering method, a melt extrusion molding method, and a solution pouring method. If necessary, the manufactured film is further subjected to processing such as secondary processing, surface treatment, and multilayer processing. In the production and processing of such a film, many rubber rolls for handling the film are used.

  Patent Document 1 discloses an automatic film winding device. With the film automatic winding device, the film is wound on the core and the work accompanying it, for example, the mounting of the core to the winding shaft, winding, cutting of the film after winding, from the winding shaft Ancillary work such as removal is automatically or semi-automatically performed. In Patent Document 1, for example, a film transport roller including a foamed rubber material as a film contact surface is described.

  For example, films used in electronic products are often intended to obtain the desired effect by transmitting, reflecting and / or absorbing light. Such a film may be generally called an optical film. The optical film has a high demand for dimensional accuracy that can affect optical characteristics, and the elimination of scratches and foreign matters, depending on the purpose of use.

  On the other hand, in the film manufacturing or processing line, with the improvement of the line speed and the thinning of the film, the rubber roll rotation speed does not synchronize with the film feed speed, and there are some cases where the film slips and the film is damaged. Has been. In particular, in the case of a soft thin film, there is a dilemma that slip occurs when the tension is reduced and the film extends when the tension is increased.

International Publication No. 2008/047546

  In view of the above situation, the problem of the present invention is that the film can be fed with a low tension such that the film is not scratched or stretched by having a stable grip force on the film. It is to provide a rubber roll for film.

  A rubber roll for film for solving the above problems comprises a roll body and a coating layer provided as an outermost layer on the roll body, and the coating layer is dispersed in a rubber material and the rubber material. A plurality of micro hollow bodies each made of a thermoplastic resin, the average particle diameter of the micro hollow bodies is 500 μm or less, and the micro hollow bodies on the surface side of the coating layer are formed on the surface of the coating layer. The opening end surface is flush with the surface of the coating layer, and the lumen surface of the opened micro hollow body forms a concave portion of the surface of the coating layer.

  According to the rubber roll for a film of the present invention, the film can be fed with a low tension so that the film is not scratched and does not stretch by having a stable gripping force against the film.

The perspective view of the rubber roll for films of an embodiment. The enlarged view which shows the film layer cross section of embodiment. The schematic diagram which shows the process of winding a film in roll shape with a film winding apparatus.

  Hereinafter, embodiments of the present invention will be described in detail.

  The rubber roll for film will be described with reference to FIG. The film rubber roll 10 includes a cylindrical roll main body 11, a coating layer 12 that forms the outermost layer of the film rubber roll 10 along the peripheral surface of the roll main body 11, and two rolls extending from both ends of the roll main body 11. Shaft portions 13a and 13b are provided.

  The material of the roll body 11 may be a high-rigidity material, and may be, for example, carbon FRP, aluminum alloy, stainless steel, and iron, but is preferably carbon FRP.

  The shaft portions 13a and 13b are generally called journals. The shaft portions 13a and 13b are used to pivotally support both ends of the roll body 11 and / or to be fitted with the driving components, and have a diameter and a length selected for that purpose. The end portions of the shaft portions 13a and 13b may be further processed as desired. The roll main body 11 and the shaft portions 13a and 13b may be formed integrally, or the roll main body 11 and the shaft portions 13a and 13b may be formed as separate parts and further combined.

  The configuration of the coating layer 12 will be described with reference to FIG. FIG. 2 is an enlarged cross-sectional view of the coating layer 12 of the rubber roll for film of FIG.

  The covering layer 12 includes a rubber material 121 and a plurality of minute hollow bodies 122. The plurality of minute hollow bodies 122 are dispersed in the rubber material 121. The plurality of minute hollow bodies 122 include a minute hollow body 122 a located on the surface side of the coating layer 12 and a minute hollow body 122 b located on the inner side of the rubber material 121. The micro hollow body 122a is cut by a curved surface along the surface 12a of the coating layer 12, and a part of the micro hollow body 122a is missing and thereby opened. This shape can be referred to as a spherical crown shape. The cut surface of the minute hollow body 122a (that is, the spherical end-shaped opening end surface 122aa) is flush with the surface of the rubber material 121. That is, in the micro hollow body 122a, the concave portion 122c is formed on the surface 12a of the covering layer 12, and the inner surface of the hollow body 122a forms a part of the surface 12a of the covering layer 12. On the surface 12a of the covering layer 12, a plurality of minute recesses 122c independent of each other are formed due to the presence of the plurality of opened minute hollow bodies 122a. Due to the plurality of recesses 122c, the surface of the covering layer 12 is rough. On the other hand, the minute hollow body 122b existing inside the rubber material 121 has a spherical shape. The micro hollow body 122b may be a true sphere, or may be a sphere with some distortion that does not affect the diameter distribution.

  The surface roughness (Ra) of the coating layer 12 is desirably JIS B0601-1994 surface roughness of 0.3 or more, but is not limited thereto. The surface roughness may be, for example, in the range of JIS B0601-1994 surface roughness of 0.3 to 42.00, for example, in the range of 2.50 to 41.50, or 2.75 to 41.25. A range is preferable. Further, the surface roughness of the coating layer 12 may have a distribution of surface roughness values, that is, variations in roughness (hereinafter also referred to as “roughness variations”). Such variation in surface roughness may be median ± 1.0, preferably median ± 0.5, more preferably median ± 0.3. For example, the surface roughness (Ra) of the coating layer 12 is in the range of 0.3 to 42.00, and the variation in the roughness is [median value −0.3] to [median value +0.3]. It may be a range. That is, when the range of the median surface roughness of the coating layer 12 is 0.6 to 41.7, the roughness value is distributed on the surface of the coating layer 12 within the range of ± 0.3 from this median value. That is, there may be variations in roughness. If the variation in roughness is in the range of ± 1.0, a stable grip force can be provided within a range that does not hinder the use of the rubber roll. It is preferable that the variation in roughness is small, for example, when the variation in roughness is ± 0.5 or ± 0.3, since a more stable grip force can be provided.

  The surface roughness (Ra) of the coating layer 12 is measured by a surface roughness measuring instrument corresponding to the JIS B0601-1994 standard. For example, it may be measured with a setting of a cut-off value of 0.8 and the number of sections of 3, for example, by a surface roughness measuring machine manufactured by Mitutoyo Corporation.

  The specific gravity of the coating layer 12 is less than 1.7, preferably less than 1.1. The specific gravity is preferably as small as possible in the range that can be appropriately used as a rubber roll.

A preferable volume ratio between the rubber material 121 and the minute hollow body 122 in the coating layer 12 is expressed by the following formula:
Porosity = [volume of micro hollow body] / [volume of entire coating layer] × 100
10% to 90%, more preferably 20% to 70%, and still more preferably 30% to 60%.

  Because of the configuration as described above, in the rubber roll, even if the surface of the coating layer is worn during use, the minute hollow body near the surface of the rubber material is brought together with the rubber material along with the wear of the surface of the coating layer. It is gradually cut and opened. Therefore, the coating layer surface has a recess that can always achieve a certain surface roughness. Therefore, the surface of the coating layer is maintained in a constant state for a long time. Thereby, the stable grip force is achieved over a long period of time. Such a surface structure of the covering layer is suitable for film feeding. That is, the rubber roll does not damage the film due to the characteristics of the coating layer as described above. Can be sent to. Moreover, since the coating layer includes the micro hollow bodies dispersed in the rubber material, the specific gravity of the coating layer is reduced, and as a result, the rubber roll can be rotated with a low torque. In addition, since the specific gravity is small, no heat is generated even when the rubber roll is rotated / rotated at the time of use, and the expansion of the coating layer is suppressed, so that the rotation speed of the rubber roll can be easily controlled even at the time of use. In addition, since the rubber roll has sufficient strength for use, there is little or no generation of impurities caused by breakage of the rubber roll.

  The raw rubber for the rubber material 121 is, for example, natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, acrylonitrile butadiene rubber, butyl rubber, chloroprene rubber, epichlorohydrin rubber, fluorine rubber, ethylene propylene rubber, acrylic rubber, silicone rubber. , Urethane rubber, chlorosulfonated polyethylene, or a combination of any two or more thereof. Although the hardness of the rubber material 121 is not limited to these, it is desirable that it is JIS A hardness 90 or less, Preferably it is 30-90, More preferably, it is 50-80. Even if the JIS A hardness exceeds 90, it may be preferably used as a rubber roll for a film depending on other conditions, particularly the material of the raw rubber used.

  The hardness is measured with a type A durometer corresponding to the JIS K6253 standard. Specifically, it may be measured by any instrument that can measure JIS A hardness, for example, a JIS A hardness measuring instrument manufactured by Kobunshi Keiki Co., Ltd.

  The minute hollow body 122 is formed of, for example, a thermoplastic resin. Examples of thermoplastic resins are copolymers of methacrylonitrile and acrylonitrile, homopolymers of vinylidene halide, copolymers containing vinylidene halide as one monomer, fluoroplastics, polyacrylic ether ketone, nitrile resin, polyamideimide , Polyarylate, polybenzimidazole, polycarbonate, thermoplastic polyester, polyetherimide, polyamide, polymethylpentene, chlorinated polyvinyl chloride, or a combination of any two or more thereof.

  The micro hollow body 122 may be formed, for example, by expanding heat-expandable microspheres having high heat resistance and tolerability with heat. The thermally expandable microsphere includes an outer shell made of a thermoplastic resin, and a foaming agent that is contained in the outer shell and vaporizes when heated. The blowing agent may be any substance that can be vaporized by heating, for example, propane, butane, pentane, hexane, heptane, octane, non-an, decane, undecane, dodecane and / or tridecane and the like. It may be a linear, branched or alicyclic liquid hydrocarbon. For example, hydrocarbon gas is contained inside the micro hollow body 122 formed by heating thermally expandable microspheres containing liquid hydrocarbons.

  The average particle diameter of the micro hollow body 122 may be 5 μm to 500 μm, and is preferably 10 μm to 500 μm. When the average particle size is less than 10 μm, a stable grip force may not be obtained depending on the blending ratio of the rubber material 121 and the micro hollow body 122. For example, when the average particle size is less than 10 μm and the surface roughness (Ra) of the coating layer 12 is less than 0.3, the air contained between the film and the film cannot be sufficiently released at the time of contact. In some cases, air slip occurs and a stable grip force cannot be obtained. When a film is handled with such a rubber roll, it is not preferable because slipping of the film cannot be stably prevented. Moreover, when the average particle diameter of the micro hollow body 122 is larger than 500 μm, it is not preferable because a plurality of uniform concave portions cannot be formed on the surface of the coating layer 12 and the strength of the rubber roll itself cannot be maintained in many cases. .

  As the micro hollow body 122, it is preferable to use an inflated microballoon or plastic microballoon generally known per se. Such pre-expanded microballoons are commercially available from Matsumoto Yushi Seiyaku Co., Ltd. as Matsumoto Microsphere (registered trademark) FE and F-DE, for example. In the case of an unexpanded microballoon, it is difficult to control the expansion rate of the microballoon and the vulcanization curing rate of the rubber material, and it is difficult to form a micro hollow body having a uniform average particle diameter.

  The rubber roll for film is manufactured as follows, for example. First, a roll body having a shaft portion as desired and having a desired length and diameter is prepared. Next, the surface of the roll body is blasted. Separately, a rubber material raw material made of a desired material and a fine hollow body are kneaded at a desired blending ratio to produce an unvulcanized rubber sheet. An adhesive is applied to the blasted portion of the roll body, and an unvulcanized rubber sheet is wound around the blasted portion and molded. This is vulcanized. Next, the surface of the vulcanized rubber formed on the peripheral surface of the roll body is polished. Thereby, a coating layer is formed on the peripheral surface of the roll body. By polishing the surface of the vulcanized rubber, a part of the minute hollow body included on the surface side of the rubber material is scraped together with the rubber material. The vulcanized rubber surface is polished concentrically with the roll body. The micro hollow body to be cut together with the rubber material is cut by a curved surface along the polished surface, and a part thereof is lost to form an opening. That is, on the surface of the coating layer, a micro hollow body opened so as to be flush with the surface of the coating layer is formed. The lumen surface of the micro hollow body is exposed to the outside through the opening. As a result, formation of a rough surface having a plurality of independent recesses constituted by the inner cavity surface of the opened micro hollow body is achieved as the coating layer surface.

  The rubber material raw material may contain a raw rubber and a desired additive such as a vulcanizing agent, a vulcanization aid, an anti-aging agent, a processing aid, a filler and / or a plasticizer.

  For example, in the case of a micro hollow body having an average particle diameter of 10 to 500 μm, the mixing ratio of the raw rubber and the micro hollow body is preferably 1 to 100 parts by weight with respect to 100 parts by weight of the raw rubber, for example. . When the coating layer is formed at this blending ratio, in many cases, the surface roughness (Ra) of the coating layer 12 is in the range of JIS B0601-1994 surface roughness of 0.3 to 42.00. Moreover, it is preferable to adjust the average particle diameter and mixing ratio of the micro hollow body so that the specific gravity of the coating layer 12 is less than 1.7 while having such characteristics. Here, the value of the porosity of the coating layer 12 may be freely changed by adjusting the average particle diameter and the blending ratio of the micro hollow body. Moreover, it may be considered that the blending ratio of the raw rubber and the micro hollow body hardly changes in the rubber roll manufacturing process. Accordingly, when the raw rubber and the fine hollow body are mixed at a blending ratio of 1 to 100 parts by weight with respect to 100 parts by weight of the raw rubber at the time of production, the same ratio, that is, the rubber material, is obtained even in the rubber roll as the final product. It can be considered that the fine hollow body is dispersed in an amount of 1 to 100 parts by weight with respect to 100 parts by weight.

  The usage example of the rubber roll for films is demonstrated, referring FIG. FIG. 3 is a schematic diagram showing a process of winding a film into a roll by a center drive type film winding apparatus. The film winding device 30 includes a guide roll 31, a contact roll 32, and a winding shaft 33. After the cylindrical winding core 35 is fitted on the outer side of the winding shaft 33, the film 34 is wound around the outer periphery of the winding core 35. The guide roll 31 is a roll for supporting the film so as to prevent twisting and sending the film from downstream to upstream in the direction and / or angle to be sent. The contact roll 32 is installed above the core 35 and contacts the outermost surface of the film roll 36 formed by winding the film 34 around the outer periphery of the core 35 with a tangent line. As a result, when the film 34 is newly stacked on the outermost surface of the film roll 36 that has already been formed, the film 34 and the outermost surface of the film roll 36 are prevented from being wrinkled or twisted. Prevent air from entering between.

  The rubber roll for film may be used as a guide roll and / or a contact roll in such a center drive film winding apparatus. Alternatively, it may be used as any roll used in any other film winding device known per se, such as a surface drive winder. Alternatively, in any apparatus for handling film, it may be used as a roll for contacting and handling the film. That is, the rubber roll for film may be understood as a rubber roll for directly contacting and handling the film in the production or processing of the film.

  The rubber roll can be used for a long period of time compared to the prior art, is easy to control even at high speed rotation, has a stable grip, reduces the generation of contaminants, reduces the occurrence of scratches on the film, There is no unevenness in static electricity, and it is possible to prevent slipping of the film that may occur when contacting the film. The rubber roll for film can be preferably used as any roll that comes into contact with the film during production and / or processing of the film.

[Example]
The rubber roll for films according to the embodiment and the rubber roll for comparison were manufactured and compared.

(1) Production of rubber roll Example 1
A rubber material, a micro hollow body, and a metal core were prepared. The rubber material is made of 100 parts by weight of acrylonitrile butadiene rubber (NBR polymer) as raw rubber, 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, 60 parts by weight of silica, bis (2-ethylhexyl) phthalate ( 40 parts by weight of DOP), 1 part by weight of 2,6-di-tert-butyl-4-methylphenol (BHT), and N-cyclohexyl-2-benzothiazolesulfenamide (CBS) as a vulcanization accelerator. 1 part by weight and 1.5 parts by weight of sulfur. A micro balloon having an average particle diameter of 100 μm manufactured by Matsumoto Yushi Seiyaku Co., Ltd. was used as the micro hollow body.

  As the core metal, a core body made of carbon FRP having a roll body and shaft portions at both ends thereof was prepared. The outer diameter of the roll body is 50 mm and the length is 450 mm.

  A rubber material raw material and 1 part by weight of a microballoon were kneaded to prepare an unvulcanized rubber sheet. The peripheral surface of the core metal roll body was blasted. An adhesive was applied to the blasted portion, an unvulcanized rubber sheet was wound around the portion, molded, and vulcanized. Next, the vulcanized rubber surface formed on the peripheral surface of the roll body was polished. Thereby, a rubber roll was obtained. This was used for the following tests as a rubber roll of Example 1. The outer diameter of the rubber roll was 70 mm.

Example 2
A rubber roll was formed by the same method and material as in Example 1 except that 10 parts by weight of a microballoon having an average particle size of 100 μm was used. This was used for the following tests as a rubber roll of Example 2. The outer diameter of the rubber roll was 70 mm.

Example 3
A rubber roll was formed by the same method and material as in Example 1 except that 40 parts by weight of a microballoon having an average particle size of 100 μm was used. This was used in the following test as a rubber roll of Example 3. The outer diameter of the rubber roll was 70 mm.

Example 4
A rubber roll was formed by the same method and the same material as in Example 1 except that 100 parts by weight of the microballoon having an average particle size of 100 μm was used. This was used in the following test as a rubber roll of Example 4. The outer diameter of the rubber roll was 70 mm.

Example 5
A rubber roll was formed in the same manner as in Example 1 except that the amount of microballoons having an average particle size of 100 μm was used at 110 parts by weight. This was used in the following test as a rubber roll of Example 5. The outer diameter of the rubber roll was 70 mm.

Example 6
A rubber roll was formed by the same method and material as in Example 1 except that 110 parts by weight of a microballoon having an average particle diameter of 5 μm was used. This was used in the following test as a rubber roll of Example 6. The outer diameter of the rubber roll was 70 mm.

Example 7
A rubber roll was formed by the same method and material as in Example 1 except that the amount of the microballoon having an average particle diameter of 500 μm was used at 10 parts by weight. This was used for the following tests as a rubber roll of Example 7. The outer diameter of the rubber roll was 70 mm.

Comparative Example 1
A rubber roll was formed by the same method and the same material and blending as in Example 1 except that the microballoon was not used. This was used in the following test as a rubber roll of Comparative Example 1. The outer diameter of the rubber roll was 70 mm.

Comparative Example 2
A rubber roll was formed by the same method and the same material as in Example 1 except that 10 parts by weight of a microballoon having an average particle diameter of 5 μm was used. This was used in the following test as a rubber roll of Comparative Example 2. The outer diameter of the rubber roll was 70 mm.

Comparative Example 3
Except for using 10 parts by weight of a microballoon having an average particle diameter of 600 μm, an attempt was made to form a rubber roll by the same method and method as in Example 1, but the coating layer was cracked to form a rubber roll. I couldn't.

Comparative Example 4
As the core metal, a core body made of carbon FRP having a roll body and shaft portions at both ends thereof was prepared. The outer diameter of the roll body is 50 mm and the length is 450 mm. The concave and convex polymer tape (Kureha elastomer rubber strip KS-3) is spirally formed in the axial direction of the roll main body and the ends of the concave and convex polymer tapes adjacent to each other on the peripheral surface are in contact with each other on the entire peripheral surface of the core body of the core metal. Affixed as follows. Thus, a rubber roll was formed and used as Comparative Example 4. The outer diameter of the rubber roll was 56 mm.

Table 1 summarizes the formulations of Examples 1 to 7 and Comparative Examples 1 to 3.

(2) Surface roughness and specific gravity of coating layer For Examples 1 to 7 and Comparative Examples 1 and 2, the surface roughness and specific gravity of the coating layer were measured. The surface roughness was measured using a surface roughness measuring machine (manufactured by Mitutoyo Corporation) corresponding to JIS B0601-1994 standard, with a cut-off value of 0.8 mm and a number of sections of 3. The specific gravity was measured using a hydrometer on the press sample after cutting out pieces having dimensions of 50 mm, 50 mm and 10 mm in length, width and thickness from the coating layer of each rubber roll. The results are shown in Table 2.

  About the rubber roll of Examples 1-7, the median value of each surface roughness is 3.75, 4.85, 8.21, 16.21, 16.32, 2.50, and 40.25, and surface roughness The variation in thickness was in the range of ± 0.3 (that is, −0.3 to +0.3). On the other hand, the median surface roughness of Comparative Examples 1 and 2 was 0.62 and 0.28, respectively.

  The specific gravity of the coating layer was 1.08, 0.86, 0.76, 0.74, 0.54, 0.78 and 0.60 for Examples 1 to 7, respectively. On the other hand, the specific gravity of the coating layers of Comparative Examples 1 and 2 was 1.34 and 0.84, respectively.

(3) Use test The performance was evaluated using the rubber rolls of Examples 1 to 7 and Comparative Examples 1, 2 and 4 as guide rolls, respectively.

  Each rubber roll was incorporated as a guide roll of a winding / unwinding device, and a polypropylene film (PP film) having a thickness of 40 μm was wound at a tension of 30 N / m and a line speed of 300 m / min. The rubber roll can rotate freely with the contact and movement of the film during operation of the apparatus. In the test, the rotational speed of each rubber roll was measured, and the slipping of the film and the state of rotation of the rubber roll were observed. The apparatus was operated for 10 minutes, a PP film having a length of 3000 m was wound around a core, and the apparatus was stopped. The rubber roll after the operation for 10 minutes and winding the 3000 m long PP film around the core was repeated 5 times was used as the rubber roll after use. About the rubber roll after use, states, such as a roll surface, were observed.

  The results are as follows.

Examples 1-7
The rubber rolls of Examples 1 to 7 all rotated at a rotational speed of 300 m / min during operation of the apparatus. In any rubber roll, no scratch was observed on the PP film wound around the core. In any rubber roll, there was no change in the surface roughness before and after use. Further, in any case of rubber rolls, defects such as idling, film slipping, and winding failure were not observed. From the above results, the rubber rolls of Examples 1 to 7 were evaluated as having no scratch on the film and having good grip properties. In addition, about the rubber roll of Example 5, abrasion was observed on the surface when it was used over a longer time.

Comparative Example 1
The rubber roll of Comparative Example 1 was rotating at a rotational speed of 142 m / min during operation of the apparatus. That is, the rubber roll of Comparative Example 1 was idling during operation.

Comparative Example 2
The rubber roll of Comparative Example 2 was rotating at a rotation speed of 156 m / min during operation of the apparatus. That is, the rubber roll of Comparative Example 2 was idling during operation. There was no significant change on the roll surface before and after use.

Comparative Example 4
The rubber roll of Comparative Example 4 was rotated at a rotational speed of 300 m / min during operation of the apparatus. Striped patterns were observed on the surface of the PP film wound around the core. This striped pattern was considered that the uneven polymer tape affixed spirally on the peripheral surface of the roll body was transferred to the film.

  Moreover, when the rubber roll provided with the uneven | corrugated polymer tape affixed helically on the surrounding surface similarly to the comparative example 4 was used over a long period of time, the space | interval of the stripe pattern transcribe | transferred to the film is the operation of an apparatus. It has been observed that it has spread over time. This is thought to be because the uneven polymer tape affixed in a spiral shape to the roll body shifted so that it could be unwound with the operation of the apparatus, and the distance between adjacent uneven polymer tapes on the peripheral surface of the roll body was increased. .

  From the above results, an embodiment in which a micro hollow body of 1 to 110 parts by weight and an average particle size of 5 μm to 500 μm is included with respect to 100 parts by weight of a rubber material, and the micro hollow body of the coating layer is opened. It was revealed that this rubber roll can handle the film well. Further, the embodiment includes an embodiment in which a micro hollow body having an average particle size of 10 μm to 500 μm is included, the micro hollow body of the coating layer is open, and the surface roughness of the coating layer is in the range of 0.3 to 41.00. It has been clarified that the rubber roll is particularly excellent as a rubber roll for a film.

10. 10. Rubber roll for film Roll body 12. Coating layer
12a. Coating layer surface 13a, 13b. Shaft part 121. Rubber material 122. Micro hollow body 122a. Open micro hollow body 122aa. Open end face 122b. Spherical hollow body 122c. Recess 30. Film winding device 31. Guide roll 32. Contact roll 33. Winding shaft 34. Film 35. Winding core 36. Film roll

Claims (8)

  A roll body, and a coating layer provided as an outermost layer on the roll body, wherein the coating layer is composed of a rubber material and a plurality of minute particles each composed of a thermoplastic resin dispersed in the rubber material. A hollow body, the average particle diameter of the micro hollow body is 500 μm or less, the micro hollow body on the surface side of the coating layer opens to the surface of the coating layer, and the opening end face thereof is a surface and a surface of the coating layer. A rubber roll for a film, characterized in that the inner cavity surface of the opened micro hollow body constitutes a recess on the surface of the coating layer.   The rubber roll for a film according to claim 1, wherein the fine hollow body is dispersed in an amount of 1 to 100 parts by weight with respect to 100 parts by weight of the rubber material.   The surface roughness of the coating layer is JIS B0601-1994 surface roughness of 0.3 or more, and the range of the surface roughness is in the range of median value -1.0 to median value +1.0. The rubber roll for a film according to claim 1 or 2.   The rubber roll for a film according to any one of claims 1 to 3, wherein an average particle diameter of the micro hollow body is 10 µm to 500 µm.   The rubber roll for a film according to any one of claims 1 to 4, wherein the specific gravity of the coating layer is less than 1.7.   The rubber roll for a film according to any one of claims 1 to 5, wherein the porosity of the coating layer is 10% to 90%.   The rubber roll for a film according to any one of claims 1 to 6, wherein the rubber material has a JIS A hardness of 90 or less.   The rubber roll for film according to any one of claims 1 to 7, wherein the thermoplastic resin is an acrylonitrile copolymer.

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