Conveyor belt

Abstract

[Problem] To provide a conveying belt for an image forming device, said conveying belt being less susceptible to rubbing noises made as a result of contact with or rubbing against a cleaning blade, even when used over a long period. [Solution] A conveying belt 1 has a cylindrical base layer 2, and a surface layer 3 that is formed on the outer peripheral surface of the base layer 2. The base layer 2 contains polyimide or polyamide-imide, and has an elastic modulus from 3-7 GPa, inclusive. The surface layer 3 is configured as a cured object from a resin composition that contains a fluororesin having a hydroxy group, an isocyanate curing agent, and a silicone copolymer. The silicone copolymer is a copolymer containing a silicone unit and another kind of unit not having a siloxane skeleton, has a hydroxy group, and contains siloxane units in a proportion of at least 95 mol% and less than 100 mol%, or from 40-70 mol%, inclusive. The silicone copolymer content in the resin composition is 1-5 parts by mass, inclusive, relative to a total 100 parts by mass of the fluororesin and the isocyanate curing agent.

Description

Technical Field

[0001] The present invention relates to a conveyance belt provided in an image forming apparatus using an electrophotographic method or an inkjet method and used for conveying a recording medium such as paper.

Background Art

[0002] In image forming apparatuses such as copiers, printers, and facsimiles using an electrophotographic method or an inkjet method, a conveyance belt configured as an endless belt is used to form an image while installing and conveying a recording medium such as paper. In an image forming apparatus, a conveyance belt used for conveying a recording medium often has a two-layer structure including a base layer and a surface layer formed on the outer peripheral surface of the base layer. Patent Documents 1 to 3 and the like disclose setting the component compositions and characteristics of the base layer and the surface layer of these conveyance belts from the viewpoint of achieving characteristics desired for the conveyance belt, such as adsorptivity and cleanability with respect to the recording medium.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In electrophotographic or inkjet image forming apparatuses, toner, ink, and paper dust adhere to the conveyance belt. Therefore, in order to remove these adherents, the surface of the conveyance belt is scraped by a cleaning blade. When the image forming apparatus is continuously used over a long period of time, vibration may occur between the cleaning blade and the conveyance belt when the cleaning blade is slid while being in contact with the conveyance belt, and a sliding noise may be generated. In particular, when changes occur in the surface shape and surface slipperiness of the conveyance belt due to long-term use, the generation of sliding noise is likely to occur.

[0005] The problem to be solved by the present invention is to provide a conveyance belt for an image forming apparatus in which sliding noise due to contact and sliding of a cleaning blade is less likely to occur even when used over a long period of time.

Means for Solving the Problem

[0006] In order to solve the above problems, the conveyance belt according to the present invention has a cylindrical base layer and a surface layer formed on the outer peripheral surface of the base layer. The base layer contains at least one of polyimide and polyamide-imide, the base layer has an elastic modulus of 3 GPa or more and 7 GPa or less, the surface layer is configured as a cured product of a resin composition containing a fluororesin having a hydroxyl group, an isocyanate curing agent, and a silicone copolymer, the silicone copolymer is a copolymer containing a silicone unit having a siloxane skeleton and another type of unit not having a siloxane skeleton, has a hydroxyl group, the content ratio of the siloxane unit in the silicone copolymer is 95 mol% or more and less than 100 mol%, and the addition amount of the silicone copolymer in the resin composition is 1 part by mass or more and 5 parts by mass or less with respect to a total of 100 parts by mass of the fluororesin and the isocyanate curing agent, and is a conveyance belt for an image forming apparatus.

[0007] In addition, another conveyor belt according to the present invention has a cylindrical base layer and a surface layer formed on the outer peripheral surface of the base layer. The base layer contains at least one of polyimide and polyamideimide, the base layer has an elastic modulus of 3 GPa or more and 7 GPa or less, the surface layer is configured as a cured product of a resin composition containing a fluororesin having a hydroxyl group, an isocyanate curing agent, and a silicone copolymer, the silicone copolymer is a copolymer containing a silicone unit having a siloxane skeleton and another type of unit not having a siloxane skeleton, has a hydroxyl group, and the content ratio of the siloxane unit in the silicone copolymer is 40 mol% or more and 70 mol% or less, and the addition amount of the silicone copolymer in the resin composition is 1 part by mass or more and 5 parts by mass or less with respect to a total of 100 parts by mass of the fluororesin and the isocyanate curing agent, and it is used as a conveyor belt for an image forming apparatus.

[0008] The surface layer preferably contains a fluorine-based or silicone-based leveling agent.

[0009] The microhardness on the surface of the surface layer is 2 30 N / mm or more and 2 200 N / mm or less.

[0010] The thickness of the base layer is preferably 50 μm or more and 90 μm or less.

[0011] The silicone copolymer is preferably composed of acrylate-modified silicone oil and OH-modified silicone oil as the silicone unit, and methyl methacrylate, 2-hydroxyethyl methacrylate, and trimethylolpropane as the other type of unit.

Advantages of the Invention

[0012] In the conveyor belt according to the above invention, since the base layer has the elastic modulus within the above-specified range, it is difficult for vibrations caused by a decrease in rigidity or surface deformation due to bending to occur between the cleaning blade. Further, the surface layer is composed of a cured product of a composition containing a silicone copolymer together with a fluororesin, and since the content ratio of siloxane units in the silicone copolymer and the addition amount of the silicone copolymer are respectively within the above-specified ranges, sufficient slipperiness is ensured on the surface of the conveyor belt. Further, the surface layer has high abrasion resistance and can maintain its high-slipperiness state even when receiving contact and sliding of the cleaning blade over a long period of time. Due to the contributions of both the base layer and the surface layer, even when the conveyor belt is used over a long period of time and the cleaning blade is brought into contact and slid, sliding noise is less likely to occur.

[0013] When the content ratio of siloxane units in the silicone copolymer is 95 mol% or more and less than 100 mol%, since the siloxane concentration in the silicone copolymer is very high, the friction coefficient of the surface layer becomes very low and the force received from the cleaning blade becomes weak. As a result, the abrasion resistance and durable slipperiness of the surface layer are improved and sliding noise is less likely to occur. Further, when the content ratio of siloxane units in the silicone copolymer is 40 mol% or more and 70 mol% or less, as a result of excellent curability of the resin composition forming the surface layer, the abrasion resistance and durable slipperiness of the surface layer are improved and sliding noise is less likely to occur.

[0014] Here, when the surface layer contains a fluorine-based or silicone-based leveling agent, the surface smoothness of the surface layer is improved. As a result, generation of sliding noise accompanying contact and sliding of the cleaning blade can be suppressed particularly effectively.

[0015] Here, when the microhardness on the surface of the surface layer is 30 N / mm 2 or more and 200 N / mm 2 or less, a conveyor belt excellent in slipperiness and bending resistance is obtained. As a result, generation of sliding noise accompanying contact and sliding of the cleaning blade can be suppressed particularly effectively.

[0016] When the thickness of the base layer is 50 μm or more and 90 μm or less, vibration of the conveyor belt can be particularly effectively suppressed due to a decrease in rigidity and deformation of the surface due to bending. As a result, generation of sliding noise associated with contact and sliding of the cleaning blade can be particularly effectively suppressed.

[0017] When the silicone copolymer is composed of acrylate-modified silicone oil and OH-modified silicone oil as silicone units, and methyl methacrylate, 2-hydroxyethyl methacrylate, and trimethylolpropane as the other type of units, a silicone copolymer in which a hydroxyl group is introduced and the content ratio of the siloxane unit is adjusted to a predetermined range can be easily prepared. And in the conveyor belt, the silicone copolymer can contribute to effective suppression of sliding noise.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0019] Hereinafter, a conveyor belt according to an embodiment of the present invention will be described with reference to the drawings. Hereinafter, various characteristics are assumed to be evaluated at room temperature. Further, that a certain constituent component is the main component of a certain material means a state in which the constituent component occupies 50% by mass or more of all the components of the material.

[0020] Figures 1 and 2 show an overview of the conveyor belt 1 according to an embodiment of the present invention. The conveyor belt 1 is used to place and convey a recording medium such as paper in an electrophotographic or inkjet image forming apparatus such as a copying machine, a printer, or a facsimile machine. The conveyor belt 1 according to the present embodiment can be preferably used particularly in an inkjet image forming apparatus.

[0021] The conveyor belt 1 is configured as an endless belt and has a base layer 2 and a surface layer 3 formed on the outer peripheral surface of the base layer 2. The conveyor belt 1 may be composed only of the base layer 2 and the surface layer 3, or another layer such as an adhesive layer may be appropriately provided between the base layer 2 and the surface layer 3.

[0022] In an image forming apparatus, the conveyor belt is subjected to the contact and sliding of a cleaning blade (hereinafter sometimes simply referred to as a blade) in order to scrape off deposits such as toner, ink, and pieces of paper. Generally, when the image forming apparatus is continuously used for a long time (hereinafter sometimes referred to as the durability time), vibrations are likely to occur between the conveyor belt and the blade while the conveyor belt is subjected to the contact and sliding of the blade for a long time. Along with the occurrence of vibrations, a squeaking sliding sound may occur when the blade is brought into contact with and slid on the conveyor belt. However, in the conveyor belt 1 according to the present embodiment, since the base layer 2 and the surface layer 3 have the configurations described below, the occurrence of a sliding sound associated with the contact and sliding of the blade is less likely to occur even during durability.

[0023] [Configuration of the base layer] The base layer 2 serves as the base material of the conveyor belt 1. The base layer 2 is formed in a cylindrical shape and has a seamless structure without joints in the circumferential direction. The base layer 2 contains at least one of polyimide and polyamide-imide. The polyimide and polyamide-imide may be functional group-modified. Since polyimide and polyamide-imide are excellent in rigidity and durability, they can be suitably used as the constituent material of the base layer 2 of the conveyor belt 1. In particular, it is preferable to configure the base layer 2 using polyimide. The base layer 2 may contain other components such as additives as long as it is mainly composed of at least one of polyimide and polyamide-imide. Examples of the additives include conductive agents such as carbon black and graphite, fillers such as calcium carbonate, release agents, flame retardants, leveling agents, defoaming agents, and the like.

[0024] The base layer 2 has an elastic modulus of 3 GPa or more and 7 GPa or less. The elastic modulus of the base layer 2 can be evaluated as the tensile elastic modulus obtained by a tensile test. When the base layer 2 has an elastic modulus of 3 GPa or more, the conveyor belt 1 has sufficiently high rigidity, and it becomes difficult for the conveyor belt 1 to generate warp and vibration. As a result, high slipperiness is easily obtained on the surface of the conveyor belt 1, contributing to the suppression of sliding noise during durability. From the viewpoint of enhancing these effects, it is more preferable that the elastic modulus of the base layer 2 is 4 GPa or more.

[0025] On the one hand, since the elastic modulus of the base layer 2 is suppressed to 7 GPa or less, deformation hardly occurs on the surface of the base layer 2. If the elastic modulus of the base layer 2 is too high, when the conveyor belt 1 is supported by two shaft members and rotated with tension applied, the bending deformation applied to the contact portion with the shaft member is difficult to be eliminated even after leaving the shaft member. As a result, through long-term rotational movement, deformation is likely to accumulate on the surface of the conveyor belt 1. Such deformation of the conveyor belt 1 leads to the formation of damage such as cracks and the generation of vibrations. By suppressing the elastic modulus of the base layer 2 to 7 GPa or less, the bending resistance of the conveyor belt 1 is increased. As a result, the occurrence of surface deformation and the accompanying vibration of the conveyor belt 1 can be suppressed. From the viewpoint of enhancing these effects, it is more preferable that the elastic modulus of the base layer 2 is 6 GPa or less.

[0026] In this way, by having an elastic modulus of 3 GPa or more and 7 GPa or less for the base layer 2, high slipperiness and bending resistance are ensured in the conveyor belt 1. As a result, even during durability, vibration is less likely to occur between the conveyor belt 1 and the blade, and the generation of sliding noise associated with the sliding of the blade is suppressed.

[0027] The thickness of the base layer 2 is not particularly limited, but it is preferably 50 μm or more, more preferably 60 μm or more. Also, it is preferably 90 μm or less, more preferably 80 μm or less. When the base layer 2 has a thickness within these ranges, it is particularly excellent in enhancing the slipperiness and bending resistance of the conveyor belt, thereby suppressing the sliding noise during durability.

[0028] [Configuration of the surface layer] The surface layer 3 is configured as a cured product of a resin composition. The resin composition constituting the surface layer 3 contains a fluororesin, an isocyanate curing agent, and a silicone copolymer. The fluororesin and the silicone copolymer each have a hydroxyl group. In the cured product, the hydroxyl groups of the fluororesin and the silicone copolymer form urethane bonds with the isocyanate groups of the isocyanate curing agent. Specifically, as described with reference to FIG. 3, the fluororesin A is crosslinked by the isocyanate curing agent B to be multiply bonded to form a main skeleton, and the silicone copolymer C is bonded to the main skeleton and distributed in the region including the surface of the surface layer 3.

[0029] The fluororesin is the main component of the resin composition constituting the surface layer 3 and serves as a binder polymer in the resin composition. A hydroxyl group is introduced into the fluororesin by modification or the like. The specific type of the fluororesin is not particularly limited as long as it can be dissolved in an appropriate solvent, formed into a liquid film, and then cured. Examples thereof include ethylene-vinyl ether fluoride copolymer (FEVE), polyvinylidene fluoride resin (PVDF), polychlorotrifluoroethylene resin (PCTFE), etc. Fluororesins commercially available as binder polymers can be preferably used. By configuring the surface layer 3 as a cured product of a resin composition containing a fluororesin, the surface layer exhibits high adhesion to the base layer 2.

[0030] The isocyanate curing agent added to the resin composition is not particularly limited as long as it is a polyfunctional isocyanate compound. A curing agent composed of blocked polyisocyanate can be preferably used.

[0031] The silicone copolymer contained in the resin composition is configured as a copolymer containing a silicone unit having a siloxane skeleton and another type of unit not having a siloxane skeleton. Preferably, in the silicone copolymer, the silicone unit and the other type of unit are block copolymerized. The silicone copolymer has a hydroxyl group.

[0032] The type of silicone unit constituting the silicone copolymer is not particularly limited, but silicone oils composed of dimethyl silicone resin, methylphenyl silicone resin, alkyl-modified silicone resin, alkyl-modified silicone resin, OH-modified silicone oil, etc. can be preferably applied. The silicone unit may be only one type or two or more types may be used in combination.

[0033] The other type of unit constituting the silicone copolymer together with the silicone unit is not particularly limited as long as it can copolymerize with the silicone unit. However, (meth)acrylic acid, (meth)acrylic acid ester, trimethylolpropane, etc., which contain a part or the whole of the structure, can be preferably used as the other type of unit. In particular, it is preferable to use a molecule having a hydroxyl group as the other type of unit because the introduction of a hydroxyl group into the silicone copolymer can be easily carried out. For example, a (meth)acrylic acid ester having a hydroxyl group can be preferably used as the other type of unit. The other type of unit may be composed of only one type of molecule or two or more types of molecules may be used in combination. When two or more types of molecules are used in combination, a block in which these two or more types of molecules are mixed and polymerized may constitute the copolymer with the silicone unit, or each type of molecule may form a block first and then constitute the copolymer with the silicone unit. Also, when two or more types of molecules are used in combination as the other type of unit, hydroxyl groups may be introduced into all types or only some types.

[0034] As a preferable example of the silicone copolymer, one composed of acrylate-modified silicone oil as the silicone unit, methyl methacrylate and 2-hydroxyethyl methacrylate as the other type of unit can be mentioned. As shown in the examples later, the surface layer 3 formed using this silicone copolymer is particularly excellent in the effect of improving slipperiness, and as a result, it shows a high effect in suppressing the sliding noise during durability.

[0035] In the silicone copolymer, the siloxane concentration is 95 mol% or more and less than 100 mol%, or 40 mol% or more and 70 mol% or less. The siloxane concentration represents, in the entire silicone copolymer, the proportion of siloxane units (Si - O units) among all monomer units, expressed in mol%. In other words, it indicates the ratio of the number of siloxane units constituting the silicone unit to the total number of monomer units constituting other types of units.

[0036] In the surface layer 3 of the conveyor belt 1, the silicone copolymer functions as a modifier for improving slipperiness. When the siloxane concentration in the silicone copolymer is 40 mol% or more, the slipperiness improvement effect can be fully exerted. Also, the wear resistance of the surface layer 3 is increased. By improving the slipperiness of the surface layer 3, the blade can slide smoothly on the surface of the conveyor belt 1, and the generation of sliding noise is suppressed. From the perspective of further enhancing the effects of improving slipperiness and wear resistance, it is particularly preferable that the siloxane concentration is 45 mol% or more, further 50 mol% or more, 55 mol% or more, 60 mol% or more.

[0037] On the other hand, if the siloxane concentration is too high, the wear resistance of the surface layer 3 will rather decrease. This is because poor curing of the resin composition causes the hardness of the surface layer 3 to become too low, and when the blade is brought into contact with the conveyor belt 1 and slid, the surface layer 3 is easily worn by the blade. The wear of the surface layer 3 impairs the slipperiness improvement effect by the surface layer 3 and causes the generation of sliding noise. By keeping the siloxane concentration at 70 mol% or less, the surface layer 3 can be sufficiently cured to enhance wear resistance. As a result, a high - slipperiness state can be maintained even during durability, and the generation of sliding noise can be suppressed. The adhesion of the surface layer 3 to the base layer 2 also increases. From these perspectives, the content ratio of siloxane units in the silicone copolymer is preferably 40 mol% or more and 70 mol% or less. This is because the resin composition for forming the surface layer 3 has excellent curability, resulting in improved wear resistance and durable slipperiness of the surface layer 3, and it is difficult for sliding noise to occur.

[0038] On the other hand, when the siloxane concentration is even higher, different from the above findings, the friction coefficient of the surface layer 3 becomes extremely low, and the force received from the cleaning blade becomes weak. As a result, the wear resistance and durable slipperiness of the surface layer 3 are improved, and the sliding noise is suppressed. This is presumably because the effect of the decrease in the friction coefficient exceeds the influence of the curability of the resin composition. From this perspective, the siloxane concentration in the silicone copolymer is preferably 95 mol% or more. More preferably, it is 96 mol% or more. On the other hand, when the siloxane concentration is 100 mol%, since there is no reaction point with the fluororesin, the silicone copolymer is not immobilized, the wear resistance and durable slipperiness are inferior, and the sliding noise is likely to occur. Therefore, from these perspectives, the siloxane concentration in the silicone copolymer is preferably 95 mol% or more and less than 100 mol%. Also, the siloxane concentration in the silicone copolymer is more preferably 99 mol% or less, and even more preferably 98 mol% or less.

[0039] In the silicone copolymer, the adjustment of the siloxane concentration can be performed, for example, by selecting the ratio of the silicone unit and other types of units that constitute the silicone copolymer. Furthermore, as other types of units, if a form of using those with a hydroxyl group and those without a hydroxyl group, such as methyl methacrylate and 2-hydroxyethyl methacrylate exemplified above, in combination is adopted, in the silicone copolymer, in addition to the siloxane concentration, the concentration of the hydroxyl group can also be adjusted.

[0040] In the resin composition constituting the surface layer 3, the addition amount of the silicone copolymer is 1 phr or more and 5 phr or less, that is, 1 part by mass or more and 5 parts by mass or less with respect to a total of 100 parts by mass of the fluororesin and the isocyanate cured product. When the addition amount of the silicone copolymer is 1 phr or more, combined with the effect that the siloxane concentration in the silicone copolymer is 40 mol% or more, in the surface layer 3, the improvement in slipperiness and wear resistance by the silicone copolymer and the effect of suppressing the sliding noise during durability can be sufficiently exerted. The addition amount of the silicone copolymer is more preferably 2 phr or more.

[0041] On the one hand, by suppressing the addition amount of the silicone copolymer to 5 phr or less, combined with the effect that the siloxane concentration in the silicone copolymer is suppressed to 70 mol% or less, it is possible to avoid poor curing of the surface layer 3, enhance the wear resistance, and effectively suppress the sliding noise during durability. The adhesion of the surface layer 3 to the base layer 2 also increases. When the addition amount of the silicone copolymer is 4 phr or less, it is more preferable.

[0042] The resin composition constituting the surface layer 3 may contain other components such as additives as appropriate in addition to the above fluororesin, isocyanate curing agent, and silicone copolymer. Examples of the additives include various additives similar to those that can be added to the base layer 2, such as conductive agents, fillers, mold release agents, flame retardants, leveling agents, defoaming agents, and organic solvents.

[0043] As the leveling agent, a fluorine-based or silicone-based leveling agent is particularly preferable. When the surface layer 3 contains a fluorine-based or silicone-based leveling agent, the surface smoothness of the surface layer 3 is improved. As a result, the generation of sliding noise associated with the contact and sliding of the cleaning blade can be particularly effectively suppressed. When the siloxane concentration in the silicone copolymer is even higher (for example, 95 mol% or more), the surface smoothness of the surface layer 3 tends to decrease due to the influence of the curability of the composition. However, when the surface layer 3 contains a fluorine-based or silicone-based leveling agent, the decrease in the surface smoothness of the surface layer 3 can be suppressed.

[0044] In the resin composition constituting the surface layer 3, the addition amount of the leveling agent is preferably 0 phr or more and 5 phr or less, that is, 0 part by mass or more and 5 part by mass or less with respect to a total of 100 parts by mass of the fluororesin and the isocyanate cured product.

[0045] The surface layer 3 configured as a cured body of the resin composition described above has a microhardness on the surface of 30 N / mm 2 or more and 200 N / mm 2It is preferably as follows. The microhardness of the surface can be measured using a microhardness tester. The load applied to the stylus during measurement may be, for example, 5.0 mN. When the microhardness of the surface of the surface layer 3 is 30 N / mm 2 or more, the wear resistance of the surface layer 3 is increased, and it shows a high effect in suppressing the sliding noise during durability. Furthermore, when the microhardness is 50 N / mm 2 or more, 70 N / mm 2 or more, it is more preferable. On the other hand, when the microhardness of the surface layer 3 is 200 N / mm 2 or less, it is easy to ensure the flexural resistance of the conveyor belt 1, and furthermore, the generation of sliding noise caused by surface deformation accompanying bending can be effectively suppressed. When the microhardness is 170 N / mm 2 or less, 150 N / mm 2 or less, it is more preferable.

[0046] The thickness of the surface layer 3 is not particularly limited. However, it is preferably kept thinner than the base layer 2. Also, if the thickness of the surface layer 3 is 25 μm or more, the characteristics exhibited by the cured product of the resin composition containing the silicone copolymer, such as improvement in slipperiness and wear resistance, can be effectively exerted. On the other hand, by keeping the thickness of the surface layer 3 at 60 μm or less, it becomes easier to highly maintain the flexural resistance of the conveyor belt 1.

[0047] The conveyor belt 1 according to this embodiment can be manufactured as follows. First, a base layer 2 is formed. The base layer 2 is formed by applying a base layer forming material in the form of a paint using an appropriate solvent or the like to the outer peripheral surface of a cylindrical or columnar mold and drying it. If necessary, heat treatment may be performed. Examples of the coating method include a dip coating method, a dispenser coating method (nozzle coating method), a roll coating method, and a ring coating method. Next, a surface layer 3 is formed by applying a resin composition for the surface layer to the surface of the formed base layer 2 and curing it. At this time, if necessary, heat treatment can be performed to promote the curing of the resin composition. For the coating of the resin composition, the same various methods as those listed above for the formation of the base layer 2 can be used. Finally, by removing the mold, a conveyor belt 1 having the surface layer 3 formed on the outer peripheral surface of the base layer 2 is obtained. Thus, since the surface layer 3 can be formed by coating a liquid composition, the manufacturing process of the conveyor belt 1 becomes simple, and the cost required for manufacturing the conveyor belt 1 can be kept low.

Example

[0048] Hereinafter, the present invention will be described in detail using examples and comparative examples. The present invention is not limited by the following examples.

[0049] [Preparation of Samples] (1) Synthesis of silicone copolymer First, a silicone copolymer used as a silicone modifier when forming the surface layer was synthesized.

[0050] The following raw materials were used for the synthesis of the silicone copolymer. · Methyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) (molecular weight: 100.12) · Butyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) (molecular weight: 128.17) · 2-Hydroxyethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) (molecular weight: 130.14) · Acrylate-modified silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd. "X-22-174DX") (molecular weight: 4600, number of siloxane units per molecular chain: 60.45) · Radical polymerization initiator: 1,1’-azobis(cyclohexane-1-carbonitrile) (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) (molecular weight: 244.34)

[0051] Using the raw materials shown in Table 1 below as Silicones A to J, silicone copolymers were synthesized by the following method. First, into a 0.5 L reaction flask, three kinds of each raw material shown in Table 1 and methyl isobutyl ketone (MIBK) were charged so that the solid content became 50%. While stirring the contents of the flask, nitrogen bubbling was carried out for 5 minutes, and then the temperature of the inner liquid was maintained at 100 °C, and the polymerization reaction was allowed to proceed for 10 hours. Thereafter, MIBK was added so that the solid content became 30%, and copolymer solutions were obtained as Silicones A to J.

[0052] Table 1 shows the amounts of each raw material used in the synthesis of Silicones A to J (unit: g). In addition, the siloxane concentration calculated from the usage amounts of each raw material is also shown (unit: mol%). Table 1 also lists commercially available hydroxy-modified silicones and non-modified silicones and their siloxane concentrations. The commercially available hydroxy-modified silicones and non-modified silicones are as follows. · Silicone K (hydroxy-modified silicone): “Silaplane FMDA21” manufactured by JNC, siloxane concentration 96 mol%, solid content 100% · Silicone L (hydroxy-modified silicone): “Silaplane FMDA26” manufactured by JNC, siloxane concentration 99 mol%, solid content 100% · Silicone M (non-modified silicone oil): “KF-54” manufactured by Shin-Etsu Chemical Co., Ltd., siloxane concentration 100 mol%, solid content 100%

[0053]

Table 1

[0054] (2) Preparation of surface layer resin composition Next, a resin composition for forming a surface layer was prepared using a silicone modifier comprising the silicone copolymer synthesized above.

[0055] In the preparation of the composition, the following were used as raw materials other than the silicone copolymer. Here, two types of fluororesins are used because these two fluororesins impart different hardnesses when cured, and the purpose is to change the microhardness of the surface of the resin composition by the mixing ratio of the two. Both of the two fluororesins have hydroxyl groups. · Fluororesin 1: "Obligate SS0054 Main Agent" manufactured by AGC Coating Tech (solid content 46%) · Fluororesin 2: "Obligate SS0062 Main Agent" manufactured by AGC Coating Tech (solid content 38%) · Isocyanate curing agent 1: "Obligate SS0054 Curing Agent" manufactured by AGC Coating Tech (solid content 83%) · Isocyanate curing agent 2: "Obligate SS0062 Curing Agent" manufactured by AGC Coating Tech (solid content 42%)

[0056] The components shown in Table 2 below were mixed to prepare Compositions A-1 to A-7, Compositions B to J, Compositions K-1 to K-4, and Compositions L to M. At this time, each component shown in Table 2 was put into a glass bottle and mixed by blade stirring for 5 minutes. For Compositions K-1 to K-4 and Compositions L to M, a commercially available silicone copolymer was used as the silicone modifier as it was, instead of the silicone copolymer synthesized above. Table 2 shows, in addition to the mass (unit: g) of each component, the addition amount of the silicone modifier in the composition (unit: phr - calculated for the solid content as the added mass relative to a total of 100 parts by mass of the fluororesin and the isocyanate cured product).

[0057]

Table 2

[0058] (3) Production of the conveyor belt Five types of polyimide were prepared as the base material. · PI-1: HCI-1300 manufactured by Hitachi Chemical Co., Ltd. (elastic modulus 5 GPa) ·PI-2: A mixture of Hitachi Chemical Co., Ltd.'s HCI-1300 and HCI-1100 (mixing ratio 1:2) (elastic modulus 3 GPa) ·PI-3: A mixture of Hitachi Chemical Co., Ltd.'s HCI-1300 and HCI-1200M (mixing ratio 1:1) (elastic modulus 7 GPa) ·PI-4: Hitachi Chemical Co., Ltd.'s HCI-1100 (elastic modulus 2 GPa) ·PI-5: Hitachi Chemical Co., Ltd.'s HCI-1200M (elastic modulus 9 GPa)

[0059] Each of the above base layer materials was coated on the surface of a cylindrical mold by the dip coating method and heated at 120 °C for 30 minutes, 150 °C for 10 minutes, 200 °C for 10 minutes, 250 °C for 10 minutes, and 350 °C for 10 minutes to form a base layer. At this time, the thickness of the base layer was controlled by the solid content of the paint and the pulling speed of the mold and was made as shown in Tables 3 and 4.

[0060] Next, a surface layer was formed on the surface of the base layer. The surface layer was formed by coating each of the resin compositions formed above on the surface of the base layer by the dipping method and further heating at 160 °C for 30 minutes to cause a curing reaction. The thickness of the surface layer was set to 45 μm for all samples. Finally, the mold was removed to produce the conveyor belts according to Examples 1 to 19 and Comparative Examples 1 to 11. For Examples 18 and 19, a fluorine-based or silicone-based leveling agent was added to the resin composition (5 phr). ·Fluorine-based leveling agent: "Surflon S-658" manufactured by AGC Seimi Chemical Co., Ltd. ·Silicone-based leveling agent: "X-22-4515" manufactured by Shin-Etsu Chemical Co., Ltd.

[0061] [Evaluation method] The following evaluations were respectively performed on each of the conveyor belts manufactured above.

[0062] (1) Microhardness of the surface layer The microhardness of the surface layer formed using each resin composition was measured with respect to the form of the conveyor belt having the surface layer formed on the base layer. The measurement was performed using a microhardness tester. The load applied to the stylus during measurement was set to 5.0 mN.

[0063] (2) Sliding noise For the paper conveyance unit WF-C20590 manufactured by Seiko Epson, each conveyance belt was set and rotated at a peripheral speed of 420 mm / second. Those in which the sliding noise did not occur for 300 hours or more were evaluated as "A+". Also, those in which the sliding noise occurred for 270 hours or more but less than 300 hours were rated as "A", those in which it occurred for 240 hours or more but less than 270 hours were rated as "B", and those in which it occurred for less than 240 hours were rated as "C". When the evaluation results are A+, A, or B, it can be determined that the generation of sliding noise during durability is sufficiently suppressed. On the other hand, when the evaluation result is C, it is determined that the suppression of sliding noise during durability is not sufficient.

[0064] (3) Abrasion resistance For the above paper conveyance unit, each conveyance belt was set and a durability test was conducted in which it was rotated at a peripheral speed of 420 mm / second for 240 hours. The film thickness before and after the durability test was measured with an eddy current meter, and the difference in film thickness (decrease amount) was taken as the wear amount. Those with a wear amount of 3 μm or less were evaluated as "A", those with a wear amount exceeding 3 μm but 5 μm or less were evaluated as "B", and those with a wear amount exceeding 5 μm were evaluated as "C". When the evaluation results are A or B, it can be determined that the abrasion resistance is sufficient. On the other hand, when the evaluation result is C, it is determined that the abrasion resistance is not sufficient.

[0065] (4) Surface smoothness Each conveyance belt was set on a mold on a cylinder with a diameter of 8.2 cm, and a surface smoothness evaluation was conducted. The 10-point average roughness (Rz) was measured in accordance with JIS B 0603:1994 using a roughness meter ("SURFCOM1400D" manufactured by ACCRETECH). Those with an Rz of less than 0.8 μm were evaluated as "A", those with an Rz of 0.8 μm or more but less than 1 μm were evaluated as "B", and those with an Rz of 1.0 μm or more were evaluated as "C". When the evaluation results are A or B, it can be determined that the surface smoothness is sufficient. On the other hand, when the evaluation result is C, it is determined that the surface smoothness is not sufficient.

[0066] (5) Flexural resistance The above paper conveyance unit was subjected to a durability test in which each conveyance belt was set and rotated at a peripheral speed of 420 mm / second for 240 hours. After the durability test, the surface of the surface layer was visually observed, and those with no cracks observed on the surface layer were rated as "A". Also, those with one crack were rated as "B", and those with two or more cracks were rated as "C". When the evaluation results are A or B, it can be determined that the flexural resistance is sufficient. On the other hand, when the evaluation result is C, it is determined that the flexural resistance is not sufficient.

[0067] (6) Durability slip resistance The above paper conveyance unit was subjected to a durability test in which each conveyance belt was set and rotated at a peripheral speed of 420 mm / second for 240 hours. The friction coefficients before and after the durability test were measured with a friction coefficient measuring instrument (HEIDON Type94i manufactured by Shinto Kagaku Co., Ltd.), and the change amount of the friction coefficient was recorded. Those with a change amount (increase amount) of the friction coefficient of less than 5% based on the value before durability were rated as "A+", those with 5% or more and less than 10% were rated as "A", those with 10% or more and less than 15% were rated as "B", and those with 15% or more were rated as "C". When the evaluation results are A+, A, or B, it can be determined that the durability slip resistance is sufficient. On the other hand, when the evaluation result is C, it is determined that the durability slip resistance is not sufficient.

[0068] [Evaluation results] The following Tables 3 and 4 show the configurations of the conveyance belts according to Examples 1 to 19 and Comparative Examples 1 to 11, and the evaluation results. In the upper row, the types of compositions used for the formation of the surface layer (the above Compositions A-1 to A7, Compositions B to J, Compositions K1 to K4, and Compositions L to M), the siloxane concentration and addition amount of the silicone modifier, the measured values of the microhardness, and the types of resins used for the formation of the base layer, the elastic modulus, and the thickness are shown. In the lower row, the evaluation results of the conveyance belts are shown.

[0069]

Table 3

[0070]

Table 4

[0071] According to Table 3, the conveyor belts of Examples 1 to 14 are all composed such that the base layer is made of polyimide having an elastic modulus of 3 GPa or more and 7 GPa or less, and the surface layer is a cured product of a resin composition in which a fluororesin having a hydroxyl group and a silicone modifier are added in an amount of 1 phr or more and 5 phr or less. The silicone modifier has a hydroxyl group, and the content ratio of the siloxane unit is 40 mol% or more and 70 mol% or less. Corresponding to the conveyor belt having such a configuration, in any of Examples 1 to 14, the evaluation result of the sliding noise is B or more, and the effect of suppressing the sliding noise during durability is sufficiently obtained. Further, in these examples, evaluations of B or more are also obtained for the abrasion resistance, flexural resistance, and durability sliding property of the surface layer, and it can be interpreted that being excellent in these respective properties exerts an effect on suppressing the sliding noise. In these examples, the surface smoothness of the surface layer is also high.

[0072] On the other hand, according to Table 4, in Comparative Examples 1 to 8 and 11, the configuration of the conveyor belt does not satisfy any of the requirements listed above. In all of these Comparative Examples 1 to 8 and 11, the evaluation result of the sliding noise is C, and the suppression of the sliding noise during durability is not sufficiently achieved. Regarding the other evaluation results, at least the durability sliding property is as low as evaluation C. Hereinafter, each comparative example will be examined.

[0073] In Comparative Example 11, as the silicone modifier added to the surface layer, a copolymer containing a silicone unit and other types of units is not used. Instead, silicone oil itself is used. Therefore, sufficient durability sliding property is not obtained on the surface layer. As a result, the effect of suppressing sliding during durability is not sufficiently achieved.

[0074] In Comparative Examples 1 to 4, a resin composition containing a silicone copolymer is used as the silicone modifier, but the siloxane concentration in the silicone copolymer or the addition amount of the silicone copolymer is not within the above-specified range. In Comparative Example 1, the siloxane concentration in the silicone modifier is less than 40 mol%. Correspondingly, sufficient durable slipperiness is not obtained on the surface layer. On the other hand, in Comparative Example 2, the siloxane concentration exceeds 70 mol%. Correspondingly, sufficient durable slipperiness is not obtained on the surface layer. From these results, it can be said that in order to ensure high durable slipperiness on the surface layer and sufficiently contribute to suppressing the sliding noise during durability, it is important to set the siloxane concentration in the range of 40 mol% or more and 70% or less.

[0075] In Comparative Example 3, the addition amount of the silicone modifier in the surface layer forming composition is less than 1 phr. Correspondingly, sufficient durable slipperiness is not obtained on the surface layer. On the other hand, in Comparative Example 4, the addition amount of the silicone modifier exceeds 5 phr. Correspondingly, sufficient durable slipperiness is not obtained on the surface layer. From these results, it can be said that in order to ensure durable slipperiness on the surface layer and sufficiently contribute to suppressing the sliding noise during durability, it is important to set the addition amount of the silicone modifier in the surface layer forming composition in the range of 1 phr or more and 5 phr or less.

[0076] In Comparative Example 5, the elastic modulus of the base layer is less than 3 GPa. Correspondingly, the durable slipperiness is low. On the other hand, in Comparative Example 6, the elastic modulus of the base layer exceeds 7 GPa. Correspondingly, the flex resistance and the durable slipperiness are low. From these results, it can be said that in order to ensure high durable slipperiness and flex resistance for the entire conveyor belt and sufficiently suppress the sliding noise during durability, it is important to configure the base layer with a polyimide having an elastic modulus of 3 GPa or more and 7 GPa or less. The same effect can be obtained when the constituent material of the base layer is polyamideimide.

[0077] In Comparative Examples 7 and 8, since the silicone modifier does not have a hydroxyl group, the silicone modifier is not immobilized on the fluororesin. Correspondingly, the wear resistance on the surface layer is slightly inferior, and sufficient durable slipperiness is not obtained. From these results, in order to ensure high durable slipperiness and wear resistance for the entire conveyor belt and sufficiently suppress the sliding noise during durability, it is necessary for the silicone modifier to have a hydroxyl group.

[0078] Also, Examples 1 to 14 are compared with each other. When Examples 1 to 4, which differ only in the siloxane concentration in the silicone modifier, are compared with each other, in Examples 1, 2, and 4 where the siloxane concentration is 45 mol% or more, particularly excellent sliding noise suppression effects and durable slipperiness are obtained compared to Example 3 where the siloxane concentration is less than 45 mol%. In particular, in Example 1 where the siloxane concentration is 60 mol% or more, the sliding noise suppression effect and durable slipperiness are extremely high. From these results, it can be said that by increasing the siloxane concentration in the silicone modifier to 45 mol% or more, and further 60 mol% or more, the durable slipperiness on the surface layer is effectively improved, and as a result, the effect of suppressing the sliding noise is enhanced. However, when Example 5 where the siloxane concentration is further increased to 70 mol% is compared with Example 1, the sliding noise suppression effect is slightly lower. From these results, it can be said that it is particularly preferable that the siloxane concentration in the silicone modifier is 45 mol% or more, and further 60 mol% or more, but it is preferably kept lower with a margin than 70 mol%.

[0079] When Examples 1, 6, and 7, which differ only in the addition amount of the silicone modifier, are compared with each other, in Example 1 where the addition amount is 2 phr or more and 3 phr or less, particularly high durability slip properties and sliding noise suppression effects are obtained. Also, when Examples 1, 11, and 12, which differ only in the microhardness of the surface layer, are compared with each other, the higher the microhardness, the slightly lower the sliding noise suppression effect and flexural resistance, while on the other hand, the lower the microhardness, the slightly lower the sliding noise suppression effect, wear resistance, and durability slip properties. In Example 1 having intermediate microhardness, it can be said that a particularly high sliding noise suppression effect is obtained due to the well-balanced excellent wear resistance, durability slip properties, and flexural resistance.

[0080] In each example other than Example 10, the silicone modifier is composed of acrylate-modified silicone oil and a silicone copolymer composed of methyl methacrylate and 2-hydroxyethyl methacrylate, but in Example 10, butyl methacrylate is used instead of methyl methacrylate (Silicone F in Table 1). Example 10 differs from Example 1 only in the molecular structure of the silicone modifier, but Example 1 is superior in the sliding noise suppression effect. From this, it can be said that by using acrylate-modified silicone oil and a silicone copolymer composed of methyl methacrylate and 2-hydroxyethyl methacrylate as the silicone modifier, the sliding noise can be effectively suppressed. It is presumed that when using other units constituting the silicone copolymer together with the silicone unit, those with a smaller number of carbon atoms will show a greater improvement effect in slipperiness brought about by the silicone unit.

[0081] Examples 1, 8, and 9 differ from each other in the elastic modulus of the base layer. In Example 1 where the elastic modulus is 4 GPa or more and 6 GPa or less, the durable sliding property is higher compared to either of Examples 8 and 9. The flexural resistance is also higher. From this, it can be said that if the elastic modulus of the base layer is 4 GPa or more and 6 GPa or less, it is excellent in both durable sliding property and flexural resistance, and as a result, a high sliding noise suppression effect can be obtained. Also, Examples 1, 13, and 14 differ from each other in the thickness of the base layer. In Example 1, the flexural resistance is superior to that of Example 14 where the base layer is relatively thick, and as a result, a high sliding noise suppression effect is obtained. Even in comparison with Example 13 where the base layer is relatively thin, the sliding noise suppression effect is higher. In Example 13, since the base layer is relatively thin, when the conveyor belt is attached to the paper conveyance unit, some wrinkles occur in the conveyor belt, so the sliding noise suppression effect is not as high as in the case of Example 1.

[0082] Also, according to Table 3, all of the conveyor belts of Examples 15 to 19 are configured such that the base layer is made of polyimide having an elastic modulus of 3 GPa or more and 7 GPa or less, and the surface layer is a cured product of a resin composition in which a fluororesin having a hydroxyl group and a silicone modifier are added in an amount of 1 phr or more and 5 phr or less. The silicone modifier has a hydroxyl group, and the content ratio of the siloxane unit is 95 mol% or more and less than 100 mol%. Corresponding to the conveyor belt having such a configuration, in any of Examples 15 to 19, the evaluation result of the sliding noise is A or more, and the effect of suppressing the sliding noise during durability is very high. Furthermore, in these examples, the abrasion resistance, flexural resistance, and durable sliding property of the surface layer are also A or more, and it can be interpreted that being excellent in these respective properties is effective in suppressing the sliding noise.

[0083] On the one hand, according to Table 4, in Comparative Examples 2, 9 to 11, the configuration of the conveyor belt does not satisfy any of the requirements listed above. In all of these Comparative Examples 2, 9 to 11, the evaluation result of the sliding noise is C, and the suppression of the sliding noise during durability has not been sufficiently achieved. Regarding other evaluation results, at least the durability slipperiness is as low as Evaluation C. Hereinafter, each comparative example will be examined.

[0084] In Comparative Examples 2, 9 to 11, a resin composition containing a silicone polymer is used as the silicone modifier, but the siloxane concentration in the silicone copolymer or the addition amount of the silicone copolymer is not within the above-specified range. In Comparative Example 2, the siloxane concentration in the silicone modifier is less than 95 mol%. Correspondingly, sufficient durability slipperiness is not obtained on the surface layer. On the other hand, in Comparative Example 11, the siloxane concentration is 100 mol%. Correspondingly, sufficient durability slipperiness is not obtained on the surface layer. From these results, it can be said that in order to ensure high durability slipperiness on the surface layer and sufficiently contribute to the suppression of the sliding noise during durability, it is important to set the siloxane concentration in the range of 95 mol% or more and less than 100%.

[0085] In Comparative Example 9, the addition amount of the silicone modifier in the surface layer forming composition is less than 1 phr. Correspondingly, sufficient durability slipperiness is not obtained on the surface layer. On the other hand, in Comparative Example 10, the addition amount of the silicone modifier exceeds 5 phr. Correspondingly, sufficient durability slipperiness is not obtained on the surface layer. From these results, it can be said that in order to ensure durability slipperiness on the surface layer and sufficiently contribute to the suppression of the sliding noise during durability, it is important to set the addition amount of the silicone modifier to the surface layer forming composition in the range of 1 phr or more and 5 phr or less.

[0086] When Examples 15 to 19 are compared with each other, it can be seen that when the siloxane concentration in the silicone copolymer becomes even higher, the surface smoothness tends to decrease (Examples 15 and 17), but by adding a fluorine-based or silicone-based leveling agent, the decrease in surface smoothness can be suppressed.

[0087] As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0088] 1 Conveyor belt 2 Base layer 3 Surface layer A Fluororesin B Isocyanate curing agent C Silicone copolymer

Claims

1. It has a cylindrical base layer and a surface layer formed on the outer peripheral surface of the base layer, The base layer contains at least one of polyimide and polyamideimide, The base layer has an elastic modulus of 3 GPa or more and 7 GPa or less, The surface layer is configured as a cured product of a resin composition containing a fluororesin having a hydroxyl group, an isocyanate curing agent, and a silicone copolymer, The silicone copolymer is a copolymer containing a silicone unit having a siloxane skeleton and another type of unit not having a siloxane skeleton, and has a hydroxyl group, The content ratio of the siloxane unit in the silicone copolymer is 95 mol% or more and less than 100 mol%, The addition amount of the silicone copolymer in the resin composition is 1 part by mass or more and 5 parts by mass or less with respect to a total of 100 parts by mass of the fluororesin and the isocyanate curing agent, a conveyance belt for an image forming apparatus.

2. It has a cylindrical base layer and a surface layer formed on the outer peripheral surface of the base layer, The base layer contains at least one of polyimide and polyamideimide, The base layer has an elastic modulus of 3 GPa or more and 7 GPa or less, The surface layer is configured as a cured product of a resin composition containing a fluororesin having a hydroxyl group, an isocyanate curing agent, and a silicone copolymer, The silicone copolymer is a copolymer containing a silicone unit having a siloxane skeleton and another type of unit not having a siloxane skeleton, and has a hydroxyl group, The content ratio of the siloxane unit in the silicone copolymer is 40 mol% or more and 70 mol% or less, The addition amount of the silicone copolymer in the resin composition is 1 part by mass or more and 5 parts by mass or less with respect to a total of 100 parts by mass of the fluororesin and the isocyanate curing agent, a conveyance belt for an image forming apparatus.

3. The surface layer contains a fluorine-based or silicone-based leveling agent, the conveyance belt according to claim 1 or claim 2.

4. The microhardness on the surface of the surface layer is 30 N / mm ２ or more and 200 N / mm ２ or less. The conveyor belt according to any one of claims 1 to 3

5. The thickness of the base layer is 50 μm or more and 90 μm or less, the conveyance belt according to any one of claims 1 to 4.

6. The silicone copolymer is composed of acrylate-modified silicone oil and OH-modified silicone oil as the silicone units, and methyl methacrylate, 2-hydroxyethyl methacrylate, and trimethylolpropane as the other type of units, and the conveyor belt according to any one of claims 1 to 5.

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