JP6484584B2 - Diaphragm member, reservoir tank having the diaphragm member, and negative pressure booster having the diaphragm member - Google Patents

Description

  The present invention relates to a diaphragm member, a reservoir tank having the diaphragm member, and a negative pressure booster having the diaphragm member.

  Conventionally, a diaphragm member is used for a reservoir tank or a negative pressure booster of a hydraulic master cylinder (for example, refer to Patent Documents 1 to 5).

  The diaphragm member has a peripheral edge fixed to the fixed object, and a flexible portion inside the peripheral edge is repeatedly bent and deformed following the pressure change in the reservoir tank or the booster shell. In a frequently operated application such as a vehicle brake, the diaphragm member also frequently bends and deforms, so that it is desired to have excellent fatigue characteristics.

  In recent years, cellulose nanofibers obtained by defusing natural cellulose fibers into nanosizes have attracted attention. Natural cellulose fiber is biomass that uses pulp such as wood as a raw material, and it is expected to reduce the environmental load by effectively using this.

  Then, the manufacturing method of the rubber composition using at least one of an oxidized cellulose fiber and a cellulose nanofiber is proposed (refer patent document 6).

JP 2007-76604 A JP 2007-78151 A JP 2012-250663 A JP 2014-141162 A Japanese Patent Laying-Open No. 2015-39905 Japanese Patent Laying-Open No. 2015-98576

  An object of the present invention is to provide a diaphragm member that reduces environmental burden and has excellent fatigue characteristics, a reservoir tank having the diaphragm member, and a negative pressure booster having the diaphragm member.

[Application Example 1]
The diaphragm member according to this application example is
A diaphragm member used for a reservoir tank having a liquid storage chamber and a cap that covers an opening of the liquid storage chamber,
Said diaphragm member includes a peripheral portion of the annular fixed in between said liquid reservoir chamber cap, and a flexible portion which deforms to flex in response to pressure changes in the interior of the liquid reservoir chamber to the inside of the peripheral edge , have a,
The diaphragm member is composed of a rubber composition containing 5 to 20 parts by mass of at least one of oxidized cellulose fiber and cellulose nanofiber with respect to 100 parts by mass of rubber.
Rubber, includes a scan styrene-Butajiengo-time,
The oxidized cellulose fiber has an average fiber diameter of 10 μm to 30 μm,
Cellulose nanofibers, the average value of the fiber diameter Ri 1nm~200nm der,
The rubber composition has a tensile strength in a tensile test according to JIS K6251 of 15 MPa or more and a breaking elongation of 420% or more.
The rubber composition, the maximum tear strength in the tear test conforming to JIS K6252 is characterized der Rukoto than 40N / mm.
[Application Example 2]
The diaphragm member according to this application example is
A diaphragm member used in a negative pressure booster for a hydraulic master cylinder for a vehicle having a booster shell,
The diaphragm member has an annular peripheral portion fixed to the inner peripheral side of the booster shell , and the inside of the booster shell is hermetically partitioned into a negative pressure chamber and a working chamber inside the peripheral portion , and have a, a flexible portion for bending deformation in response to pressure changes in the interior,
The diaphragm member is composed of a rubber composition containing 5 to 20 parts by mass of at least one of oxidized cellulose fiber and cellulose nanofiber with respect to 100 parts by mass of rubber.
Rubber, includes a scan styrene-Butajiengo-time,
The oxidized cellulose fiber has an average fiber diameter of 10 μm to 30 μm,
Cellulose nanofibers, the average value of the fiber diameter Ri 1nm~200nm der,
The rubber composition has a tensile strength in a tensile test according to JIS K6251 of 15 MPa or more and a breaking elongation of 420% or more.
The rubber composition has a maximum tear strength in a tear test according to JIS K6252.
But it characterized the Der Rukoto more than 40N / mm.

  According to the diaphragm member according to this application example, it is possible to reduce the environmental load by including at least one of the oxidized cellulose fiber and the cellulose nanofiber, and it is excellent in fatigue characteristics.

[Application Example 3]
In the diaphragm member according to this application example,
The rubber may further include ethylene / propylene rubber .

[Application Example 4]
The reservoir tank according to this application example is
A reservoir tank having the diaphragm member,
Before has a Ki貯 liquid chamber, and a cap covering the opening of the liquid reservoir chamber,
The peripheral portion is fixed between the liquid storage chamber and the cap.

[Application Example 5]
The negative pressure booster according to this application example is
A negative pressure booster having the diaphragm member,
Before has the Kivu Sutasheru,
The periphery of the diaphragm member is fixed to the inner peripheral side of the booster shell, and the inside is hermetically divided into a negative pressure chamber and a working chamber.

It is sectional drawing which shows typically the hydraulic master cylinder for vehicles which has a diaphragm member for vehicle brakes concerning one Embodiment. It is sectional drawing which shows typically the negative pressure booster for hydraulic master cylinders for vehicles which has a diaphragm member for vehicle brakes concerning one Embodiment. It is a figure which shows typically the dispersion | distribution process in the manufacturing method of the rubber composition which concerns on one Embodiment. It is a figure which shows typically the dispersion | distribution process in the manufacturing method of the rubber composition which concerns on one Embodiment. It is a figure which shows typically the dispersion | distribution process in the manufacturing method of the rubber composition which concerns on one Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are essential constituent requirements of the present invention.

The diaphragm member according to the present embodiment is a diaphragm member used for a reservoir tank having a liquid storage chamber and a cap that covers the opening of the liquid storage chamber, and the diaphragm member includes the liquid storage chamber and the cap. possess a peripheral portion of the annular fixed between a flexible portion which deforms to flex in response to pressure changes in the interior of the liquid reservoir chamber to the inside of the peripheral edge of the said diaphragm member, rubber 100 relative parts by weight, consists of at least one 5 parts by mass to a rubber composition containing 20 parts by weight of oxidized cellulose fibers and the cellulose nanofibers, rubber comprises a scan styrene-Butajiengo arm, cellulose fibers are oxidized, the average fiber diameter value is 10 m to 30 m, the cellulose nanofibers, the average value of the fiber diameter Ri 1nm~200nm der, the rubber composition, JIS K625 The tensile strength at a tensile test based is at least and elongation at break 420% or more 15 MPa, the rubber composition, the Der Rukoto maximum tear strength is 40N / mm or more at the tear test according to JIS K6252 Features.
The diaphragm member according to the present embodiment is a diaphragm member used for a negative pressure booster for a hydraulic master cylinder for a vehicle having a booster shell, and the diaphragm member is an annular shape fixed to the inner peripheral side of the booster shell. A peripheral portion, and a flexible portion that divides the inside of the booster shell into a negative pressure chamber and a working chamber in an airtight manner inside the peripheral portion, and bends and deforms according to a pressure change in the inside. The diaphragm member is made of a rubber composition containing 5 to 20 parts by mass of at least one of oxidized cellulose fibers and cellulose nanofibers with respect to 100 parts by mass of rubber. The rubber contains styrene-butadiene rubber, and is oxidized cellulose. The fiber has an average fiber diameter of 10 μm to 30 μm, and the cellulose nanofiber has an average fiber diameter of 1 nm to 200 n. m, the rubber composition has a tensile strength in a tensile test according to JIS K6251 of 15 MPa or more and a breaking elongation of 420% or more, and the rubber composition has a maximum tear in a tear test according to JIS K6252. strength is characterized der Rukoto than 40N / mm.

Further, the reservoir tank according to the present embodiment, the a reservoir tank having a diaphragm member having a front Ki貯 liquid chamber, and a cap covering the opening of the liquid reservoir chamber, said peripheral portion, It is fixed between the liquid storage chamber and the cap.

The negative pressure booster according to the present embodiment is a vacuum booster having a diaphragm member, before having Kivu Sutasheru, the inner peripheral side of said booster shell, and fixing the peripheral portion of the diaphragm member The interior is hermetically partitioned into a negative pressure chamber and a working chamber.

1. Vehicle Hydraulic Master Cylinder A vehicle hydraulic master cylinder 10 according to this embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view schematically showing a vehicle hydraulic master cylinder 10 having a vehicle brake diaphragm member 40 according to an embodiment. In addition, although the diaphragm member 40 for vehicle brakes is demonstrated in the following description, it is not restricted to this, You may use as a diaphragm member in another use.

  A vehicle hydraulic master cylinder 10 shown in FIG. 1 is a vehicle brake, for example, an automobile brake device. A vehicle brake diaphragm member 40 (hereinafter referred to as “diaphragm member 40”) is fixed to the reservoir tank 13 of the vehicle hydraulic master cylinder 10. The reservoir tank 13 is attached to, for example, an upper part of the tandem cylinder body 12 and forms a part of the vehicle hydraulic master cylinder 10.

  The reservoir tank 13 has a reservoir body 30 fixed to the upper part of the cylinder body 12 and a hydraulic fluid injection chamber 32 formed in the upper part of the reservoir body 30. The liquid storage chamber 34 stores hydraulic fluid by the reservoir body 30 and the hydraulic fluid injection chamber 32. The hydraulic fluid injection chamber 32 has a substantially cylindrical shape, and is offset from the reservoir body 30 attached to the cylinder body 12 toward the front side of the vehicle body due to the attachment space to the vehicle body. A diaphragm member 40 and a cap 50 that cover the opening 38 are attached to the opening 38 of the liquid storage chamber 34 formed on the upper surface of the hydraulic fluid injection chamber 32. The reservoir body 30, the hydraulic fluid injection chamber 32, and the cap 50 are made of synthetic resin.

  The cylinder body 12 is made of a metal, for example, an aluminum alloy, and has two boss portions 22 and 24 that are formed to protrude toward the reservoir body 30, and a flange 26 that is formed between the two boss portions 22 and 24. The reservoir body 30 is fitted into the boss portions 22 and 24, and a flange 33 and a flange 26 which are formed to protrude from the reservoir body 30 toward the cylinder body 12 are fixed by screws (not shown). 12 is integrated.

  The diaphragm member 40 has a substantially circular basin-shaped outer shape, and an annular peripheral portion is sandwiched and fixed between the inside of the cap 50 and the opening 38, and a bottom surface portion 44 formed near the center is stored. It sinks into the liquid chamber 34. More specifically, the peripheral edge portion of the diaphragm member 40 is placed on the top surface of the opening 38, and a cap 50 is placed thereon to be screwed into the hydraulic fluid injection chamber 32, and is integrated with the reservoir tank 13 together with the cap 50. Attached to.

  The cap 50 is formed in a substantially cylindrical shape with a bottom, and a plurality of protrusions that press and lock the peripheral edge of the diaphragm member 40 against the opening 38 are formed on the inner peripheral surface. Therefore, a through hole is formed between the cap 50 and the diaphragm member 40, and an atmosphere chamber 36 communicating with the atmosphere is formed between the cap 50 and the diaphragm member 40. Accordingly, the diaphragm member 40 partitions the liquid storage chamber 34 and the atmospheric chamber 36 on the cap 50 side.

  The diaphragm member 40 has a function of flexibly deforming in the axial direction of the hydraulic fluid injection chamber 32 in response to a pressure change in the liquid storage chamber 34 and adjusting the pressure in the liquid storage chamber 34. Further, a communication hole 42 is formed at the center of the diaphragm member 40, and the liquid storage chamber 32 and the atmospheric chamber 36 are communicated to maintain the inside of the liquid storage chamber 32 at atmospheric pressure. In addition, this communication hole 42 may be formed in the peripheral part side of the diaphragm member 40, and may be formed in a slit-like stop valve. Further, a bellows portion may be formed on the diaphragm member 40 to facilitate the deformation of the hydraulic fluid injection chamber 32 in the axial direction.

  For example, when the hydraulic fluid is affected by braking heat or the like and the air in the liquid storage chamber 34 expands, the diaphragm member 40 causes the air in the liquid storage chamber 34 to be discharged from the communication hole 42 to the atmosphere chamber 36. The bottom surface 44 of the diaphragm member 40 is deformed toward the opening 38, thereby avoiding an increase in pressure in the liquid storage chamber 34. Further, for example, when the level of the hydraulic fluid in the liquid storage chamber 34 is lowered due to the lining wear of the friction pad of the brake device, the atmosphere is introduced into the liquid storage chamber 34 through the communication hole 42, or the diaphragm By deforming the bottom surface portion 44 of the member 40 toward the liquid storage chamber 34 side, the inside of the liquid storage chamber 34 is prevented from being in a negative pressure state.

2. Negative pressure booster for vehicle hydraulic master cylinder M A negative pressure booster B for vehicle hydraulic master cylinder M will be described with reference to FIG. FIG. 2 is a cross-sectional view schematically showing a negative pressure booster B for a vehicle hydraulic master cylinder M having a vehicle brake diaphragm member 66 according to an embodiment. In addition, although the diaphragm member 66 for brakes for vehicles is demonstrated in the following description, it is not restricted to this, You may use as a diaphragm member in another use.

  The vehicle hydraulic master cylinder M shown in FIG. 2 is a vehicle brake, for example, an automobile brake device. A vehicle brake diaphragm member 66 (hereinafter referred to as “diaphragm member 66”) is an inner periphery of a booster shell 60 in a negative pressure booster B for a vehicle hydraulic master cylinder M (hereinafter referred to as “hydraulic master cylinder M”). It is fixed to the side by fixing the peripheral edge of the diaphragm member 66.

  In FIG. 2, the booster shell 60 of the negative pressure booster B includes a front shell half 61 and a rear shell half 62 that are each formed in a bowl shape and are connected to each other at opposite ends. Here, the “front part” is the hydraulic master cylinder M side (left side in FIG. 2), and the “rear part” is the brake pedal P side (right side in FIG. 2). The front shell half 61 and the rear shell half 62 are made of steel plates, and they are connected via a pair of steel tie rods 70 (only one of which is shown in FIG. 1). . The pair of tie rods 70 are arranged so as to sandwich the central axis of the booster shell 60, and the cylinder body Ma of the hydraulic master cylinder M is formed on the front end face of the front shell half 61 using these tie rods 70. The rear shell half 62 is fastened to the front surface of the vehicle body F of the automobile by using these tie rods 70. For example, the front shell half 61 and the rear shell half 62 are caulked and connected to each other without using the tie rod 70, and the rear shell half 62 is fixed to the vehicle body F with dedicated bolts. A hydraulic master cylinder M can also be attached to the front shell half 61.

The interior of the booster shell 60 is airtightly divided into a front negative pressure chamber 63 and a rear working chamber 64 by a diaphragm member 66 sandwiched between the front shell half 61 and the rear shell half 62. A booster piston 65 that can reciprocate back and forth within the booster shell 60 is disposed on the front surface of the diaphragm member 66. The diaphragm member 66 is integrally formed with a cylindrical slide seal 72 that can air-tightly pass through an intermediate portion of the booster piston 65 and slide on the tie rod 70.

  A resin valve cylinder 80 is integrally coupled to the central portions of the booster piston 65 and the diaphragm member 66. The valve cylinder 80 is slidably supported via a bearing bush 73 on a bearing cylinder 82 that protrudes rearward from the central portion of the rear shell half 62.

  The negative pressure chamber 63 is connected to a negative pressure source V (for example, inside the intake manifold of the internal combustion engine) via a negative pressure introduction pipe 84 and a check valve 89.

  At the rear end of the valve cylinder 80, an air introduction port 71 for introducing air into the valve cylinder 80 is provided. In the valve cylinder 80, an input rod 90 connected to the brake pedal P, and a control valve for switching the working chamber 64 to the negative pressure chamber 63 and the air introduction port 71 in accordance with the longitudinal movement of the input rod 90 are provided. 81 is disposed. That is, the control valve 81 shuts off the working chamber 64 from the atmosphere introduction port 71 and communicates with the negative pressure chamber 63 when the input rod 90 moves backward, and connects the working chamber 64 to the negative pressure chamber when the input rod 90 moves forward. It has a well-known configuration that can be cut off from 63 and communicated with the air inlet 71. Between the input rod 90 and the valve cylinder 80, an input return spring 83 that urges the input rod 90 in the backward direction is contracted.

  The control valve 81 includes a valve piston 88 slidably fitted to the valve cylinder 80 and connected to the front end portion of the input rod 90. A reaction force piston 87 is formed at the front end of the valve piston 88. The

  A key member 93 that abuts the front end portion of the bearing cylinder 82 and defines the backward limit of the valve cylinder 80 and the input rod 90 is attached to the valve cylinder 80.

  Further, the valve cylinder 80 is provided with an operating piston 85 projecting forward and a small-diameter cylinder hole 86 penetrating through the central portion of the operating piston 85, and a reaction force piston 87 is slidable in the small-diameter cylinder hole 86. Mated. A cup body 91 is slidably fitted to the outer periphery of the operating piston 85, and the cup body 91 is filled with a flat elastic piston 92 facing the operating piston 85 and the reaction force piston 87.

  An output rod 95 is continuously provided on the front surface of the cup body 91. Therefore, the output rod 95 is slidably supported by the valve cylinder 80 via the cup body 91. The output rod 95 is connected to the rear end portion of the master piston Mb penetrating the central portion of the front shell half 61 of the hydraulic master cylinder M.

  Between the front wall of the booster shell 60 and the front end surface of the valve cylinder 80, a booster return spring 97 for urging the valve cylinder 80 in the backward direction is contracted.

  The diaphragm member 66 includes a flexible portion 68 that extends forward from a peripheral portion 67 sandwiched between the front shell half 61 and the rear shell half 62 and then turns back to reach the outer periphery of the booster piston 65. And a piston pressing portion 69 that is located on the center side of the flexible portion 68 and overlaps the back surface of the booster piston 65. As an example, an annular thick portion larger than the flexible portion 68 and the piston pressing portion 69 is formed at the connecting portion between the flexible portion 68 and the piston pressing portion 69. Although formed so as to embrace the outer periphery, it is not limited to this.

  Next, the operation of this embodiment will be described.

  In the idle state of the negative pressure booster B, that is, in the released state of the input rod 90, the key member 93 attached to the valve cylinder 80 contacts the front end of the bearing cylinder 82, and the reaction force piston 87 has a rear end surface on the key member 93. The input rod 90 is held in a retracted limit by the set load of the input return spring 83. At this time, the control valve 81 blocks between the working chamber 64 and the air introduction port 71, and communicates between the working chamber 64 and the negative pressure chamber 63. Therefore, the negative pressure in the negative pressure chamber 63 is transmitted to the working chamber 64, and the working chamber 64 and the negative pressure chamber 63 have the same pressure, so that the booster piston 65 and the valve cylinder 80 are moved backward by the biasing force of the booster return spring 97. Retained.

  Here, when the input rod 90 is advanced together with the valve piston 88 against the set load of the input return spring 83 by depressing the brake pedal P to brake the vehicle, the control valve 81 is moved into the working chamber 64 and the negative pressure chamber. 63 is cut off, and the working chamber 64 and the air introduction port 71 are communicated with each other. As a result, the atmosphere is introduced into the working chamber 64 from the atmosphere introduction port 71, and the working chamber 64 is set to a pressure higher than that of the negative pressure chamber 63. Therefore, the diaphragm member 66 obtains a forward thrust based on the pressure difference between the booster piston 65 and the booster piston 65. The valve cylinder 80, the operating piston 85, the elastic piston 92, the cup body 91, the output rod 95 and the like are advanced against the force of the booster return spring 97, so that the output rod 95 drives the master piston Mb forward to The brake can be activated.

  When the output rod 95 is actuated, the reaction force compresses the elastic piston 92, and a part thereof bulges into the small diameter cylinder hole 86 and abuts against the reaction force piston 87. Due to this contact, a part of the reaction force of the output rod 95 is fed back to the input rod 90 via the elastic piston 92, so that the operator can perceive the magnitude of the output of the output rod 95. . The output of the output rod 95 increases with a boost ratio determined by the ratio of the pressure receiving areas of the operating piston 85 and the reaction force piston 87 that are in contact with the elastic piston 92.

  After reaching the boost limit point at which the pressure difference between the negative pressure chamber 63 and the working chamber 64 reaches the maximum, the output of the output rod 95 is the maximum thrust due to the pressure difference of the booster piston 65 and the operation to the input rod 90. Sum with input.

  When the pedaling force is released from the brake pedal P to release the brake operating state of the vehicle, first, the input rod 90 and the valve piston 88 are moved backward by the force of the input return spring 83. Accordingly, the control valve 81 blocks the working chamber 64 from the atmosphere introduction port 71 and communicates with the negative pressure chamber 63, so that the introduction of the atmosphere into the working chamber 64 is prevented, while the air in the working chamber 64 is Is sucked into the negative pressure source V through the negative pressure chamber 63 and the pressure difference between them is eliminated, so that the booster piston 65 is also retracted by the elastic force of the booster return spring 97 and the operation of the hydraulic master cylinder M is released. To go. Then, as described above, the key member 93 attached to the valve cylinder 80 comes into contact with the front end of the bearing cylinder 82, so that the booster piston 65 and the input rod 90 return to the resting state again.

3. Diaphragm member The shape of the diaphragm members 40 and 66 varies depending on the object to be fixed, as shown in FIGS. 1 and 2, but the basic configuration is the same. The fixed object in FIG. 1 is a liquid storage chamber 34. The fixed object in FIG. 2 is a booster shell 60.

  Diaphragm members 40 and 66 include annular peripheral portions 46 and 67 fixed to a fixed object (liquid storage chamber 34 and booster shell 60), and fixed objects (liquid storage chamber) inside the peripheral portions 46 and 67. 34, and a flexible portion 48, 68 that bends and deforms in response to a pressure change inside the booster shell 60). The diaphragm members 40 and 66 are not limited to vehicle brakes, and may be used as diaphragm members in other applications.

  Diaphragm members 40 and 66 used for vehicle braking have fatigue characteristics against repeated bending deformation caused by braking operation. In particular, vehicle brakes are exposed to high temperatures by brake operation, but the diaphragm members 40 and 66 are also excellent in fatigue characteristics in a high temperature region.

4). Rubber composition Diaphragm members 40 and 66 are made of a rubber composition containing 0.1 to 60 parts by mass of at least one of oxidized cellulose fiber and cellulose nanofiber with respect to 100 parts by mass of rubber. Here, “parts by mass” indicates “phr” unless otherwise specified, and “phr” is an abbreviation for “parts per undred of resin or rubber”, and represents the percentage of external additives such as additives to rubber and the like. It is.

  The rubber composition is a rubber composition in which at least one of defibrated oxidized cellulose fiber and cellulose nanofiber is dispersed. The rubber composition may further contain carbon black.

  For example, when the rubber composition is used in a diaphragm member of a reservoir tank or a negative pressure booster, it can reduce environmental burden by including at least one of oxidized cellulose fibers and cellulose nanofibers, and can improve fatigue characteristics. Can be excellent.

  The rubber composition may have a tensile strength of 15 MPa or more in a tensile test based on JIS K6251. The diaphragm member uses a rubber composition having a high tensile strength, so that when the diaphragm is used for a brake, cracks hardly occur even if the diaphragm member is repeatedly bent and deformed each time the brake is operated. The rubber composition can have a tensile strength of 15 MPa or more and 30 MPa or less in the same test, and can further have a tensile strength of 16 MPa or more and 25 MPa or less.

  The rubber composition may have a maximum tear strength of 40 N / mm or more in a tear test according to JIS K6252. The test method will be described later. The maximum tear strength is obtained by measuring the maximum tear force (N) obtained by conducting a tear test and dividing the measurement result by the thickness of the test piece. The diaphragm member uses a rubber composition having a high maximum tear strength, so that when the diaphragm is used for a brake, cracks are not easily generated even when the diaphragm is repeatedly bent and deformed each time the brake is operated. The rubber composition can have a maximum tear strength of 40 N / mm or more and 70 N / mm or less in the same test, and a maximum tear strength of 40 N / mm or more and 60 N / mm or less.

  The rubber composition has a large number of times until the test piece breaks in a fatigue test (described later in Examples). That is, the rubber composition is excellent in fatigue life at high temperature, and a diaphragm member excellent in heat resistance and fatigue durability can be obtained.

  In addition, the rubber composition has at least one of oxidized cellulose fibers and cellulose nanofibers defibrated to rubber and has a diameter of at least one of oxidized cellulose fibers and cellulose nanofibers having a diameter of 0.1 mm or more. It is preferable not to have an aggregate of 1 mm or more. The aggregate containing at least one of the oxidized cellulose fiber and the cellulose nanofiber is a mass in which these fibers are gathered together. The aggregate of the oxidized cellulose fiber, the aggregate of the cellulose nanofiber, and the oxidized cellulose fiber and the cellulose It contains aggregates composed of nanofibers.

According to the rubber composition in the present embodiment, it does not have an aggregate and is reinforced by dispersing in a state where at least one of oxidized cellulose fiber and cellulose nanofiber is defibrated, and has rigidity, strength, and low linear expansion. Excellent coefficient and fatigue resistance. However, it is difficult to prove that aggregates of cellulose nanofibers are not present in the rubber composition. When the rubber composition contains only cellulose nanofibers, aggregates can be confirmed by observation with an optical microscope (see Patent Document 6). Since the same dispersion process is used in this embodiment, the rubber composition does not have an aggregate of 0.1 mm or more of cellulose nanofibers.

  The rubber, the oxidized cellulose fiber, and the cellulose nanofiber constituting the rubber composition will be described later.

5. Manufacturing method of rubber composition A manufacturing method of a rubber composition used for a diaphragm member is a mixing step in which an aqueous solution containing at least one of oxidized cellulose fibers and cellulose nanofibers and rubber latex are mixed to obtain a first mixture. The drying step includes drying the first mixture to obtain a second mixture, and the step of dispersing the second mixture with an open roll to obtain a rubber composition.

5-1. Raw material First, the raw material used for a mixing process is demonstrated.

5-1-1. Aqueous solution The aqueous solution includes an aqueous solution containing oxidized cellulose fibers, an aqueous solution containing cellulose nanofibers, and an aqueous solution containing oxidized cellulose fibers and cellulose nanofibers.

  The aqueous solution containing oxidized cellulose fibers can be produced, for example, by an oxidation process in which natural cellulose fibers are oxidized to obtain oxidized cellulose fibers.

  The aqueous solution containing cellulose nanofibers can be obtained, for example, by a production method including an oxidation step of oxidizing natural cellulose fibers to obtain oxidized cellulose fibers, and a refining step of refining oxidized cellulose fibers.

  The aqueous solution containing oxidized cellulose fibers and cellulose nanofibers can be obtained by mixing an aqueous solution containing oxidized cellulose fibers and an aqueous solution containing cellulose nanofibers.

  Here, natural cellulose fibers include, for example, wood pulp, cotton-based pulp, bacterial cellulose and the like. More specifically, examples of the wood pulp include coniferous pulp, hardwood pulp, and the like. Examples of the cotton pulp include cotton linter and cotton lint. Non-wood pulp includes Mention may be made of straw pulp, bagasse pulp and the like. At least one of these natural cellulose fibers can be used.

Natural cellulose fibers have a structure composed of cellulose microfibril bundles and lignin and hemicellulose filling them. That is, it is presumed that the cellulose microfibril and / or the cellulose microfibril bundle has a structure in which hemicellulose covers and further this is covered with lignin. Cellulose microfibrils and / or cellulose microfibril bundles are firmly bonded by lignin to form plant fibers. Therefore, it is preferable that lignin in the plant fiber is removed in advance from the viewpoint that aggregation of the cellulose fiber in the plant fiber can be prevented. Specifically, the lignin content in the plant fiber-containing material is usually about 40% by mass or less, preferably 10
It is about mass% or less. Further, the lower limit of the lignin removal rate is not particularly limited, and it is preferably as close to 0% by mass. The lignin content can be measured by the Klason method.

  As the cellulose microfibril, a cellulose microfibril having a width of about 4 nm exists as a minimum unit, and this can be called a single cellulose nanofiber. In the present invention, the “cellulose nanofiber” is a material obtained by unraveling natural cellulose fibers and / or oxidized cellulose fibers to the nanosize level. In particular, the average value of the fiber diameters can be 1 nm to 200 nm, and further 1 nm. Can be ˜150 nm, in particular cellulose microfibrils and / or cellulose microfibril bundles of 1 nm to 100 nm. That is, the cellulose nanofiber can include a single cellulose nanofiber alone or a bundle of a plurality of single cellulose nanofibers.

  The aspect ratio (fiber length / fiber diameter) of the cellulose nanofiber can be an average value of 10 to 1000, more preferably 10 to 500, and particularly preferably 100 to 350.

  In addition, the average value of the fiber diameter and fiber length of a cellulose nanofiber is an arithmetic average value measured about at least 50 or more of the cellulose nanofiber within the visual field of an electron microscope.

  First, an oxidation process adds water with respect to the natural cellulose fiber used as a raw material, processes with a mixer etc., and prepares the slurry which disperse | distributed the natural cellulose fiber in water.

  Next, natural cellulose fibers are oxidized in water using an N-oxyl compound as an oxidation catalyst to obtain oxidized cellulose fibers. Examples of N-oxyl compounds that can be used as an oxidation catalyst for cellulose include 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (hereinafter also referred to as TEMPO), 4-acetamide-TEMPO, 4-carboxy-TEMPO, 4-phosphonooxy-TEMPO, etc. can be used.

  After the oxidation step, for example, a purification step of repeating washing with water and filtration can be carried out to remove impurities other than oxidized cellulose fibers contained in the slurry, such as unreacted oxidant and various by-products. The solvent containing the oxidized cellulose fiber is, for example, in a state of being impregnated with water. At this stage, the oxidized cellulose fiber is not defibrated up to the unit of cellulose nanofiber. As the solvent, water can be used. For example, in addition to water, organic solvents (alcohols, ethers, ketones, etc.) soluble in water can be used depending on the purpose.

  Oxidized cellulose fiber has a carboxyl group by modifying a part of the hydroxyl group of cellulose nanofiber with a substituent having a carboxyl group.

  The average value of the fiber diameter of the oxidized cellulose fiber can be 10 μm to 30 μm. In addition, the average value of the fiber diameter of an oxidized cellulose fiber is an arithmetic average value measured about at least 50 or more of the oxidized cellulose fiber in the visual field of an electron microscope.

  The oxidized cellulose fiber can be a bundle of cellulose microfibrils. The oxidized cellulose fiber does not need to be fibrillated to the unit of cellulose nanofiber in the mixing step and the drying step described later. Oxidized cellulose fibers can be fibrillated into cellulose nanofibers in the refinement process.

  In the micronization step, the oxidized cellulose fiber can be stirred in a solvent such as water, and cellulose nanofibers can be obtained.

  In the miniaturization step, the solvent as the dispersion medium can be water. Moreover, as a solvent other than water, water-soluble organic solvents such as alcohols, ethers, and ketones can be used alone or in combination.

  The agitation treatment in the miniaturization process includes, for example, a disaggregator, a beater, a low pressure homogenizer, a high pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a short axis extruder, a twin screw extruder, an ultrasonic agitator, and a home juicer mixer. Etc. can be used.

  Moreover, solid content concentration of the solvent containing the oxidized cellulose fiber in the refining treatment can be, for example, 50% by mass or less. When this solid content concentration exceeds 50% by mass, high energy is required for dispersion.

  An aqueous solution containing cellulose nanofibers can be obtained by the refinement process. The aqueous solution containing cellulose nanofibers can be a colorless, transparent or translucent suspension. In the suspension, cellulose nanofibers, which are fibers oxidized and defibrated and refined, are dispersed in water. That is, in this aqueous solution, the cellulose nanofibers can be obtained by weakening the strong cohesive force between the microfibrils (hydrogen bonding between the surfaces) by introducing carboxyl groups in the oxidation process, and further through the refinement process. And by adjusting the conditions of the oxidation step, the carboxyl group content, polarity, average fiber diameter, average fiber length, average aspect ratio, etc. can be controlled.

  The aqueous solution thus obtained can contain 0.1% by mass to 10% by mass of cellulose nanofibers. Moreover, for example, it can be an aqueous solution diluted to a solid content of 1% by mass of cellulose nanofibers. Furthermore, the aqueous solution can have a light transmittance of 40% or more, a light transmittance of 60% or more, and particularly 80% or more. The transmittance of the aqueous solution can be measured as the transmittance at a wavelength of 660 nm using an ultraviolet-visible spectrophotometer.

5-1-2. Rubber latex As the rubber latex, a natural rubber latex solution and a synthetic rubber latex solution can be used.

  The natural rubber latex solution is a natural product produced by the metabolic action of plants, and a natural rubber / water system in which the dispersion solvent is water can be used. Synthetic rubber latex solutions include, for example, styrene / butadiene rubber, butadiene rubber, methyl methacrylate-butadiene rubber, 2-vinylpyridine-styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, silicone rubber, fluorine rubber, etc. Can be produced by emulsion polymerization.

  The rubber latex has a large number of fine rubber particles dispersed in a dispersion solvent.

5-1-3. Carbon black Carbon black of various grades using various raw materials can be used. The carbon black can be 10 nm to 500 nm, and the average particle size can be 100 nm or more and 300 nm or less. The average particle diameter of carbon black can be obtained by observing by imaging with a scanning electron microscope and measuring 2000 or more particle diameters of basic constituent particles and arithmetically averaging them.

  As such carbon black, for example, reinforcing carbon black such as SAF, ISAF, HAF, SRF, T, GPF, FT, and MT can be used. By using carbon black having a relatively large particle size, the rubber composition is reinforced with oxidized cellulose fibers and cellulose nanofibers in which rubber components in the gaps formed between the carbon blacks are dispersed while maintaining the flexibility of the rubber composition. be able to. As the carbon black, MT grade carbon black can be used.

5-1-4. Rubber Rubber is a solid rubber other than the rubber latex described above, natural rubber (NR), epoxidized natural rubber (ENR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), chloroprene rubber (CR ), Ethylene / propylene rubber (EPR, EPDM), butyl rubber (IIR), chlorobutyl rubber (CIIR), acrylic rubber (ACM), silicone rubber (Q), fluororubber (FKM), butadiene rubber (BR), epoxidized butadiene Rubbers such as rubber (EBR), epichlorohydrin rubber (CO, CEO), urethane rubber (U), polysulfide rubber (T), and mixtures thereof can be used. In particular, a diaphragm member for a reservoir tank that is used for a vehicle master cylinder and contacts with a brake fluid, or a diaphragm member of a negative pressure booster that is repeatedly deformed by an operator's operation, includes ethylene / propylene rubber or styrene / rubber as rubber. Butadiene rubber is preferred. For example, a low polarity rubber such as ethylene / propylene rubber (EPDM) generates free radicals by setting the kneading temperature to a relatively high temperature (for example, 50 to 150 ° C. in the case of EPDM). Cellulose nanofibers can be dispersed. EPDM (ethylene / propylene / diene / copolymer), EPM (ethylene / propylene copolymer) and the like can be used as the ethylene / pyropyrene rubber, and EPDM is preferred. The rubber is usually used after being crosslinked and does not contain a thermoplastic elastomer.

  The reason why the solid rubber is blended in addition to the rubber latex is that the entire rubber component of the diaphragm member is manufactured from the rubber latex because it is too realistic to be processed. The solid rubber component may be the same type as the rubber used in the rubber latex, or may be a rubber that is compatible with the rubber component of the rubber latex.

5-2. Each manufacturing process FIGS. 3-5 is a figure which shows typically the manufacturing method of the rubber composition which concerns on one Embodiment.

5-2-1. Mixing step In the mixing step, an aqueous solution containing at least one of oxidized cellulose fibers and cellulose nanofibers and rubber latex are mixed to obtain a first mixture. As the mixing step, for example, a roll kneading method using a roll kneading device, a stirring operation using a propeller type stirring device, a homogenizer, a rotary stirring device, and an electromagnetic stirring device, or a manual stirring operation can be used. In particular, a roll kneading method can be used for the mixing step.

  As the roll kneading apparatus used for the roll kneading method, for example, an open roll can be used. Moreover, the roll kneading apparatus used for the roll kneading method can use, for example, two rolls or three rolls.

The mixture of the aqueous solution and the rubber latex is gradually introduced into a roll kneading apparatus in which the distance between the rolls is set to a predetermined interval. The distance between the rolls can be set to such a distance that the mixture of the aqueous solution and the rubber latex is wound around the rolls, and the mixture does not fall between the rolls. The mixture charged in the roll kneader is gradually increased in viscosity by being kneaded. When the viscosity of the mixture becomes high, the mixture can be taken out from the roll kneading apparatus, and the distance between the rolls can be set to be further narrowed, and can be charged again into the roll kneading apparatus. This step can be performed multiple times.

  By performing the mixing step, it can be expected that at least one of the oxidized cellulose fiber and the cellulose nanofiber enters the rubber fine particles while passing between the rolls. In particular, by using the roll kneading method, the reinforcing effect by the fibers can be further improved as compared with other stirring operations.

  The 1st mixture obtained at a mixing process is 0.1 mass part-60 mass parts at least one of an oxidized cellulose fiber and a cellulose nanofiber with respect to 100 mass parts of rubber solid components by the mass ratio after a drying process. Can be included. When at least one of the oxidized cellulose fiber and the cellulose nanofiber is 0.1 part by mass or more, a reinforcing effect is obtained, and if it is 60 parts by mass or less, processing after the drying step is possible.

5-2-2. Drying step The drying step is a step of obtaining the second mixture by drying the first mixture obtained in the mixing step. For example, since the first mixture contains moisture, a general method for removing water can be adopted. For example, a known drying method such as natural drying, oven drying, freeze drying, spray drying, or pulse combustion can be employed for the drying process.

  The drying step can be performed at a temperature at which the rubber, oxidized cellulose fiber, and cellulose nanofiber are not thermally decomposed, and can be dried by heating at 100 ° C., for example.

  The second mixture includes a rubber component and at least one of oxidized cellulose fiber and cellulose nanofiber. A 2nd mixture can contain 0.1-60 mass parts of at least one of an oxidized cellulose fiber and a cellulose nanofiber with respect to 100 mass parts of rubber | gum, for example. Furthermore, the second mixture can contain 1 part by mass to 50 parts by mass of at least one of the oxidized cellulose fiber and the cellulose nanofiber, and particularly can contain 5 parts by mass to 40 parts by mass. When at least one of oxidized cellulose fibers and cellulose nanofibers is contained in an amount of 0.1 parts by mass or more in the second mixture, a reinforcing effect of the rubber composition can be obtained, and at least one of oxidized cellulose fibers and cellulose nanofibers in the solvent. If it contains 60 mass parts or less, it can process easily.

5-2-3. Dispersing Step In the dispersing step, a rubber composition can be obtained by thinly passing the second mixture containing at least one of oxidized cellulose fibers and cellulose nanofibers with an open roll.

  First, before thinning, as shown in FIG. 3, the second mixture 130 wound around the first roll 110 can be masticated, and the molecular chains of the rubber in the second mixture are moderated. To produce free radicals. The free radicals of the rubber generated by mastication are likely to be combined with at least one of oxidized cellulose fibers and cellulose nanofibers.

  Next, as shown in FIG. 4, a kneading step is performed in which the compounding agent 180 is appropriately charged into the bank 134 of the second mixture 130 wound around the first roll 110 and kneaded to obtain an intermediate mixture. it can. Here, the compounding agent 180 includes a reinforcing agent containing carbon black, solid rubber other than rubber latex, and further includes, for example, a crosslinking agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization retarder, a softening agent, a plasticizer, Curing agents, reinforcing agents, fillers, anti-aging agents, colorants, acid acceptors and the like can be included. These compounding agents can be added to the rubber at an appropriate time during the mixing process.

  The step of obtaining the intermediate mixture 136 (FIG. 5) by the steps of FIGS. 3 and 4 is not limited to the open roll method, and for example, a closed kneading method or a multi-screw extrusion kneading method can also be used.

  The intermediate mixture 136 (FIG. 5) is obtained by combining oxidized cellulose fibers and cellulose with respect to 100 parts by mass of rubber in which the rubber solid component in the rubber latex in the mixing step and the rubber component in the compounding agent 180 added in the dispersing step are combined. At least one of the nanofibers may include 0.1 to 60 parts by mass. By adding rubber in the dispersion step, the load of the drying step can be reduced by using a small amount of rubber latex in the mixing step. Therefore, the rubber component added in the dispersing step is preferably more than the rubber solid component in the rubber latex, and can be, for example, 50 mass% to 99 mass% in the rubber component in the intermediate mixture 136.

  Furthermore, thinning can be performed as shown in FIG. The thinning step can be a step of obtaining an uncrosslinked rubber composition 150 by thinning at 0 ° C. to 50 ° C. using an open roll 100 having a roll interval of 0.5 mm or less. In this step, the roll interval d between the first roll 110 and the second roll 120 is set to, for example, 0.5 mm or less, more preferably 0 mm to 0.5 mm, and the intermediate mixture obtained in FIG. 136 can be put into the open roll 100 and thinning can be performed once to several times. For example, the thinning can be performed about 1 to 10 times. When the surface speed of the first roll 110 is V1, and the surface speed of the second roll 120 is V2, the ratio of the surface speeds (V1 / V2) in thinness is 1.05 to 3.00. And can be 1.05-1.2. By using such a surface velocity ratio, a desired shear force can be obtained.

  The rubber composition 150 extruded from between the narrow rolls as described above is greatly deformed as shown in FIG. 5 by the restoring force due to the elasticity of the rubber, and at that time, at least one of the oxidized cellulose fiber and the cellulose nanofiber moves greatly together with the rubber. To do. The rubber composition 150 obtained through thinning is rolled with a roll and dispensed into a sheet having a predetermined thickness, for example, 100 μm to 500 μm.

  In this thinning process, in order to obtain as high a shearing force as possible, the roll temperature can be set to, for example, 0 ° C. to 50 ° C., and further set to a relatively low temperature of 5 ° C. to 30 ° C. be able to. The measured temperature of the rubber composition can also be adjusted to 0 ° C. to 50 ° C., and further adjusted to 5 ° C. to 30 ° C.

  By adjusting to such a temperature range, it is possible to defibrate at least one of oxidized cellulose fiber and cellulose nanofiber using the elasticity of rubber, and disperse the defibrated cellulose nanofiber in the rubber composition. it can.

  Due to the high shearing force in this thinning process, a high shearing force acts on the rubber, and at least one of the aggregated oxidized cellulose fibers and cellulose nanofibers is separated from each other so as to be pulled out one by one into the rubber molecules. , Dispersed in rubber. In particular, since rubber has elasticity and viscosity, at least one of oxidized cellulose fiber and cellulose nanofiber can be defibrated and dispersed. And the rubber composition 150 excellent in the dispersibility and dispersion stability (at least one of an oxidized cellulose fiber and a cellulose nanofiber is hard to re-aggregate) of at least one of an oxidized cellulose fiber and a cellulose nanofiber can be obtained.

More specifically, when rubber and at least one of oxidized cellulose fiber and cellulose nanofiber are mixed with an open roll, rubber having viscosity penetrates into at least one of oxidized cellulose fiber and cellulose nanofiber. When the surface of at least one of the oxidized cellulose fiber and the cellulose nanofiber is moderately high by, for example, oxidation treatment, it can be easily bonded to a rubber molecule. Next, when a strong shearing force was applied to the rubber, at least one of the oxidized cellulose fiber and the cellulose nanofiber moved with the movement of the rubber molecules, and further aggregated by the restoring force of the rubber due to elasticity after shearing. At least one of the oxidized cellulose fiber and the cellulose nanofiber is separated and dispersed in the rubber. In particular, the open roll method is preferable because it can measure and manage not only the roll temperature but also the actual temperature of the mixture.

5-2-4. Coagulation step A coagulation step of coagulating the rubber latex in the first mixture can be further included between the mixing step and the drying step.

  Since the first mixture obtained in the mixing step in 5-2-1 contains a large amount of moisture as it is, it takes a long time to remove moisture in the drying step in 5-2-2. . Therefore, in the coagulation step, a predetermined amount of a known coagulant that coagulates rubber latex is added to the first mixture that is an aqueous solution, and the mixture is stirred and mixed. The rubber component in the first mixture is solidified by the coagulant. The coagulation step can include dehydration and washing for the coagulum. Dehydration and washing can be repeated multiple times.

  The dehydration in this step only needs to remove water to the extent that the drying time in the drying step can be shortened, and separates the solidified rubber component and moisture to some extent. Dehydration can be performed using, for example, a general rotary dehydrator (centrifugation), a rubber film roll, a press machine, or the like. Moreover, the washing | cleaning in this process can be performed with water, for example.

  As the coagulant, a known latex coagulant can be appropriately employed depending on the type of rubber latex in the first mixture. As the coagulant, for example, a known acid or salt can be used, and the polymer flocculant may be used in place of or together with the salt. Examples of the acid used for the coagulant include formic acid, acetic acid, propionic acid, citric acid, oxalic acid, sulfuric acid, hydrochloric acid, and carbonic acid. As a salt used for the coagulant, for example, sodium chloride, aluminum sulfate, calcium nitrate and the like can be used. As the polymer flocculant, any of anionic, cationic and nonionic polymer flocculants can be used.

  Since a large amount of water can be removed from the first mixture in the coagulation process, the heating time of the drying process performed after the coagulation process can be shortened, and the working efficiency is improved.

5-2-5. Diaphragm Member Molding Process The kneaded rubber composition is molded by a rubber molding process generally employed using a mold having a desired diaphragm member shape. Examples of the molding process include press molding, extrusion molding, and injection molding. In the molding step, the rubber component of the rubber composition containing a crosslinking agent is crosslinked. As the cross-linking agent, for example, a known cross-linking agent applied to rubber appropriately selected according to the use can be used.

  When the diaphragm member thus obtained is used for a reservoir tank or a negative pressure booster, the environmental load can be reduced by the diaphragm member including at least one of oxidized cellulose fiber and cellulose nanofiber. Further, according to such a reservoir tank or negative pressure booster, the diaphragm member is excellent in fatigue characteristics, so that it can be deformed flexibly according to the pressure change for a long period of time.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

(1) Preparation of sample (1-1) Examples 1-4
Obtaining an aqueous solution:
Cellulose nanofibers were obtained in the same manner as in the method disclosed in Production Example 1 of JP2013-18918A.

  Specifically, after sufficiently stirring bleached kraft pulp of softwood with ion-exchanged water, TEMPO 1.25% by mass, sodium bromide 12.5% by mass, sodium hypochlorite 28.4% with respect to 100 g of pulp mass. Mass% was added in this order at 20 ° C. Sodium hydroxide was added dropwise to maintain the pH at 10.5, and an oxidation reaction was performed. After the oxidation reaction was performed for 120 minutes, dropping was stopped to obtain an aqueous solution containing 10% by mass of TEMPO-oxidized oxidized cellulose fiber. The oxidized cellulose fiber had a fiber diameter of 10 μm to 30 μm and a fiber length of 1 mm to 5 mm, which were the same as those of the original pulp.

Furthermore, the oxidized cellulose fiber was sufficiently washed with ion-exchanged water and then dehydrated. Thereafter, the oxidized cellulose fiber was adjusted to a solid content of 1% by mass with ion-exchanged water and refined using a high-pressure homogenizer to obtain an aqueous dispersion containing 1% by mass of cellulose nanofibers. The average fiber diameter of the cellulose nanofiber was 3.3 nm, and the average aspect ratio was 225.

Mixing process:
Styrene-butadiene rubber (hereinafter referred to as “SBR”) latex (manufactured by JSR 0561: aqueous dispersion with a solid content of 69% by mass, 10.3 pH, viscosity 440 (mPa · s) ), Surface tension 32 (mN / m), average particle size 700 (nm), Tg-63 ° C.), and mixed at a rotational speed of 10,000 rpm using a juicer mixer.

  After mixing by the mixer, the mixture was passed through a three roll (M-50) manufactured by EXAKT having a nip of 10 μm at a rotation speed of 200 rpm to perform additional mixing to obtain a first mixture.

Drying process:
The first mixture was heat-dried in an oven set at 50 ° C. for 4 days to obtain a second mixture. The blending ratio in the second mixture after drying was SBR solid content of 100 phr and cellulose nanofibers of 60 phr.

Dispersion process:
The second mixture was masticated at a roll interval of 1.5 mm, and SBR, EPDM and carbon black, which are solid rubbers, were added and kneaded to obtain a mixture having the composition shown in Table 1. Further, this mixture was put into an open roll having a roll interval of 0.3 mm, and thinned at 10 to 30 ° C. to obtain a rubber composition sample. At this time, the surface speed ratio of the two rolls was set to 1.1. Thinning was repeated 5 times. In addition, the compounding quantity in Table 1 and Table 2 is a mass part (phr).

Vulcanization process:
A sheet obtained by adding 8 parts by mass of peroxide as a cross-linking agent to a rubber composition sample obtained through thinning and compression-molding the sheet at 170 ° C. for 10 minutes, and forming a sheet-like cross-linked rubber composition sample having a thickness of 1 mm Got.

(1-2) Comparative Examples 1 and 2
In Comparative Examples 1 and 2, each raw material was put into an open roll with a roll interval of 1.5 mm and kneaded so as to have the composition shown in Table 2, and further 8 parts by mass of peroxide was added as a crosslinking agent. The sheet was compression molded at 170 ° C. for 10 minutes to obtain a sheet-like crosslinked rubber composition sample having a thickness of 1 mm.

In Tables 1 and 2,
“SBR” is a blended amount of 1503, specific gravity 0.93, Mooney viscosity 52 (ML _{1 + 4} (100 ° C.)) manufactured by JSR, in addition to the solid content of the SBR latex.
“EPDM” is EP24 manufactured by JSR, specific gravity 0.87, Mooney viscosity 42 (ML _{1 + 4} (100 ° C.)),
"MT carbon" is carbon black of MT grade (average particle diameter and DBP oil absorption are manufacturer's published values) with an average particle diameter of 200 nm and DBP oil absorption of 25 ml / 100 g.
“Cellulose” was an oxidized cellulose nanofiber having an average fiber diameter of 3.3 nm and an average aspect ratio of 225 obtained in the above step.

(2) Basic characteristic test The rubber hardness (Hs (JIS A)) of the rubber composition sample was measured based on the JIS K6253 test.

  About the rubber composition sample, the tensile strength (TS (MPa)) and the elongation at break (Eb (%)) are test pieces punched into a JIS No. 6 dumbbell shape using a tensile tester manufactured by Shimadzu Corporation. , Measured at 23 ± 2 ° C. under a tensile speed of 500 mm / min based on JIS K6251.

(3) Tear test A rubber composition sample was punched into an angle-shaped test piece without incision in JIS K6252, and a tear test was performed in accordance with JIS K6252 at a pulling speed of 500 mm / min using an autograph AG-X manufactured by Shimadzu Corporation. The tear strength (Tr (N / mm)) was calculated by measuring the maximum tearing force (N) and dividing the measurement result by the test piece thickness of 1 mm.

(4) Fatigue life test About the rubber composition sample, as a fatigue life (indicated as "fatigue (2 N / mm)" in Tables 3 and 4), the test sample was 10 mm x 4 mm wide x 1 mm thick (the long side was Punched into a strip-shaped test piece in a row direction), a 1 mm depth incision was made with a razor blade in the width direction from the center of the long side of the test piece, and the test piece was tested using a TMA / SS6100 testing machine manufactured by SII. The short side of both ends is held by a chuck, and a fatigue test is performed by repeatedly applying a tensile load (1 N / mm to 2 N / mm) under the condition of a frequency of 1 Hz in an air atmosphere at 120 ° C., and the test piece breaks. The number of times until it was measured.

(5) Durability test A diaphragm member was prepared from a rubber composition sample and attached to a reservoir tank 13 and a booster shell 60 as shown in FIGS. 1 and 2, and the braking operation was repeated 1 million times at an atmospheric temperature of 150 ° C. . The appearance of the diaphragm member after the test was inspected, and the durability was evaluated as “X” when the crack was generated and “◯” when the crack was not generated. In addition, a normal durability test is about 200,000 times to 500,000 times.

  From the results of Tables 3 and 4, the rubber compositions of Examples 1 to 4 were reinforced with cellulose nanofibers, and the tensile strength was the same or higher than the samples of Comparative Examples 1 and 2. In addition, the rubber compositions of Examples 1 to 4 showed higher values of maximum tear strength and tear fatigue life than the samples of Comparative Examples 1 and 2.

  Moreover, from the results of Tables 3 and 4, it was found that the diaphragm members of Examples 1 to 4 were superior in heat resistance and durability as compared to the diaphragm members of Comparative Examples 1 and 2.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

  DESCRIPTION OF SYMBOLS 10 ... Fluid pressure master cylinder, 12 ... Cylinder body, 13 ... Reservoir tank, 22, 24 ... Boss part, 26 ... Flange, 30 ... Reservoir main body, 32 ... Hydraulic fluid injection chamber, 33 ... Flange, 34 ... Liquid storage chamber, 36 ... Atmospheric chamber, 38 ... Opening portion, 40 ... Diaphragm member, 42 ... Communication hole, 44 ... Bottom portion, 46 ... Rim portion, 48 ... Flexible portion, 50 ... Cap, 60 ... Booster shell, 61 ... Front shell Half body, 62 ... rear shell half body, 63 ... negative pressure chamber, 64 ... working chamber, 65 ... booster piston, 66 ... diaphragm member, 67 ... peripheral part, 68 ... flexible part, 69 ... piston pressing part, 70 ... Tie rod, 71 ... Air introduction port, 72 ... Slide seal, 73 ... Bearing bush, 80 ... Valve, 81 ... Control valve, 82 ... Bearing cylinder, 83 ... Input return spring, 84 ... Negative pressure introduction pipe, 85 ... Operating piston 86 ... Small diameter cylinder hole, 87 ... Reaction piston, 88 ... Valve piston, 89 ... Check valve, 90 ... Input rod, 91 ... Cup body, 92 ... Elastic piston, 93 ... Key member, 95 ... Output rod, 97 ... Booster return spring, 100 ... open roll, 110 ... first roll, 120 ... second roll, 130 ... second mixture, 134 ... bank, 136 ... intermediate mixture, 150 ... rubber composition, 180 ... compounding agent, V1, V2 ... rotational speed, d ... roll interval, B ... negative pressure booster, F ... car body, M ... master cylinder, Ma ... cylinder body, Mb ... master piston, P ... brake pedal, V ... negative pressure source

Claims (5)

A diaphragm member used for a reservoir tank having a liquid storage chamber and a cap that covers an opening of the liquid storage chamber,
Said diaphragm member includes a peripheral portion of the annular fixed in between said liquid reservoir chamber cap, and a flexible portion which deforms to flex in response to pressure changes in the interior of the liquid reservoir chamber to the inside of the peripheral edge , have a,
The diaphragm member is composed of a rubber composition containing 5 to 20 parts by mass of at least one of oxidized cellulose fiber and cellulose nanofiber with respect to 100 parts by mass of rubber.
Rubber, includes a scan styrene-Butajiengo-time,
The oxidized cellulose fiber has an average fiber diameter of 10 μm to 30 μm,
Cellulose nanofibers, the average value of the fiber diameter Ri 1nm~200nm der,
The rubber composition has a tensile strength in a tensile test according to JIS K6251 of 15 MPa or more and a breaking elongation of 420% or more.
The rubber composition Ru der maximum tear strength is 40N / mm or more at the tear test according to JIS K6252, the diaphragm member. A diaphragm member used in a negative pressure booster for a hydraulic master cylinder for a vehicle having a booster shell,
The diaphragm member has an annular peripheral portion fixed to the inner peripheral side of the booster shell , and the inside of the booster shell is hermetically partitioned into a negative pressure chamber and a working chamber inside the peripheral portion , and have a, a flexible portion for bending deformation in response to pressure changes in the interior,
The diaphragm member is composed of a rubber composition containing 5 to 20 parts by mass of at least one of oxidized cellulose fiber and cellulose nanofiber with respect to 100 parts by mass of rubber.
Rubber, includes a scan styrene-Butajiengo-time,
The oxidized cellulose fiber has an average fiber diameter of 10 μm to 30 μm,
Cellulose nanofibers, the average value of the fiber diameter Ri 1nm~200nm der,
The rubber composition has a tensile strength in a tensile test according to JIS K6251 of 15 MPa or more and a breaking elongation of 420% or more.
The rubber composition has a maximum tear strength in a tear test according to JIS K6252.
Der Ru, diaphragm member but 40N / mm or more. In claim 1 or 2,
The rubber member further includes an ethylene / propylene rubber . A reservoir tank having the diaphragm member according to claim 1 ,
Before has a Ki貯 liquid chamber, and a cap covering the opening of the liquid reservoir chamber,
The peripheral edge portion is a reservoir tank fixed between the liquid storage chamber and the cap. A negative pressure booster having the diaphragm member according to claim 2 ,
Before has the Kivu Sutasheru,
A negative pressure booster for a hydraulic master cylinder for a vehicle, wherein a peripheral edge portion of the diaphragm member is fixed to an inner peripheral side of the booster shell and the inside is hermetically divided into a negative pressure chamber and a working chamber.

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