JP2021081029A - Silicone rubber-based curable composition and fluid-driven actuator including the same - Google Patents

Abstract

To provide a silicone rubber-based curable composition having excellent expansion stability and expansion durability.SOLUTION: A silicone rubber-based curable composition in the present invention is used to form a part of a fluid-driven actuator. For a cured product of the silicone rubber-based curable resin composition, a stroke change rate after 1 hour is expressed as SC1(%) and a tear strength is expressed as TS(N/mm), SC1 and TS satisfy SC1≤50 and 20≤TS.SELECTED DRAWING: Figure 1

Description

The present invention relates to a silicone rubber-based curable composition and a fluid-driven actuator using the same.

So far, various developments have been made on silicone rubber used for tube members in actuators. As a technique of this kind, for example, the technique described in Patent Document 1 is known. Patent Document 1 describes that silicone rubber is used for a tubular elastic body in a fluid-driven actuator (claim 6 of Patent Document 1 and the like).

Japanese Unexamined Patent Publication No. 2015-180829

However, as a result of the examination by the present inventor, there is room for improvement in terms of expansion stability and expansion durability in the silicone rubber for the tube member mounted on the fluid-driven actuator described in Patent Document 1. found.

Silicone rubber used in a fluid-driven actuator is required to have a characteristic that strain deformation due to fluid pressure is small during repeated expansion, that is, expansion stability.
The present inventor has focused on the relationship between the characteristics of silicone rubber and expansion stability, and found that the expansion stability of silicone rubber can be controlled by using the stroke change rate during expansion as an index. It was.
However, the expanded silicone rubber may be damaged because its mechanical strength is lower than that when it is not expanded.
Based on these circumstances, the present inventor, who has made further studies, has found that the mechanical strength of the silicone rubber at the time of expansion can be controlled by using the tear strength as an index.

As a result of further diligent research based on these findings, it is possible to stably evaluate the expansion stability and expansion durability of silicone rubber by using both the stroke change rate and tear strength after expansion as indicators, and expansion. It was found that by setting the subsequent stroke change rate to a predetermined value or less and the tear strength to a predetermined value or more, it is possible to realize a silicone rubber that is excellent in expansion stability and expansion durability and is suitably used for a fluid-driven actuator. , The present invention has been completed.

According to the present invention
A silicone rubber-based curable composition used to form a part constituting a fluid-driven actuator.
When the stroke change rate after 1 hour of the cured product of the silicone rubber-based curable resin composition measured by the following procedure is SC1 (%) and the tear strength is TS (N / mm).
A silicone rubber-based curable composition is provided in which SC1 and TS satisfy SC1 ≦ 50 and 20 ≦ TS.
(Measurement procedure of stroke change rate)
Using the cured product of the silicone rubber-based curable composition, a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004), and when the chucks were held at a stress of 1 MPa, the temperature was 25 ° C. , The elongation of the obtained dumbbell-shaped No. 3 test piece is measured over time.
When the stress is 1 MPa, it is set to 0 h, and the stroke amount after a predetermined time n (h) is set to En (%) = [movement distance between chucks (mm)] ÷ [initial distance between chucks (60 mm)] × 100. The stroke change rate is calculated from the measured stroke amount from En based on the following formula.
Stroke change rate after n hours SCn (%) = (En-E0) / E0 × 100
(Measurement procedure of tear strength)
Using the cured product of the silicone rubber-based curable composition, a crescent-shaped test piece is prepared in accordance with JIS K6252 (2001), and the tear strength of the obtained crescent-shaped test piece is measured at 25 ° C. .. The unit is N / mm.

Further, according to the present invention.
Provided is a fluid-driven actuator comprising a tube member formed of a cured product of the silicone rubber-based curable composition described above.

According to the present invention, a silicone rubber-based curable composition having excellent expansion stability and expansion durability, and a fluid-driven actuator using the same are provided.

It is a figure which shows an example of the structure of the fluid drive type actuator of this embodiment. (A) is a sectional view taken along the line AA of FIG. 1, (b) is a sectional view taken along the line BB of FIG. 1, and (c) is a sectional view taken along the line CC of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are designated by the same reference numerals, and description thereof will be omitted as appropriate. Moreover, the figure is a schematic view and does not match the actual dimensional ratio.

The silicone rubber-based curable composition of the present embodiment will be described.

The silicone rubber-based curable composition of the present embodiment is used to form a part constituting a fluid-driven actuator.
In this silicone rubber-based curable composition, the stroke change rate after 1 hour of the cured product of the silicone rubber-based curable resin composition measured by the following procedure is SC1 (%), and the tear strength is TS ( When N / mm), SC1 and TS satisfy SC1 ≦ 50 and 20 ≦ TS.

According to the findings of the present inventor, the expansion stability and expansion durability of the silicone rubber can be stably evaluated by using each of the initial stroke change rate and the tear strength as indexes, and the stroke after 1 hour. It has been found that expansion stability and expansion durability can be improved by setting the value of the rate of change to be equal to or less than the above upper limit value and the value of the tear strength to be equal to or more than the above lower limit value.

As a result of the examination by the present inventor, the following findings were obtained. It has been found that reducing the amount of filler in the silicone rubber can reduce the initial stroke change rate, but on the other hand, the tear strength is lowered and the durability of the silicone rubber is lowered.

Therefore, as a result of diligent studies, the crosslink density and uneven distribution of the crosslink structure can be controlled by appropriately selecting the components of the silicone rubber-based curable composition such as vinyl group-containing organopolysiloxane, and the initial stroke change rate can be determined. It was found that the tear strength of silicone rubber can be increased while improving it. Although the detailed mechanism is not clear, the cross-linking state can be appropriately controlled by using two different types of vinyl group-containing organopolysiloxane together or by using a low vinyl group organopolysiloxane, so that the initial stroke change rate can be improved. However, it is considered that the tear strength of the silicone rubber can be increased.

Such a tube member using silicone rubber is mechanical because the fluctuation of the expansion state such as the expansion rate and the expansion direction becomes small even when the expansion is continuously maintained by the fluid pressure or when the tube member is repeatedly expanded. It was found that it can be stably converted into kinetic energy.

Further, it was found that such a tube member using silicone rubber has excellent durability because breakage such as cracks is suppressed even when a fluid such as air is injected / discharged and repeatedly expanded. ..

The silicone rubber-based curable composition of the present embodiment is excellent in expansion stability and expansion durability, and can realize a silicone rubber suitable for a fluid-driven actuator.

In the present embodiment, the fluid drive type actuator is a drive device that expands or contracts a tube member using a fluid such as gas or liquid and converts it into mechanical motion. Specific examples of the fluid include air, a gas such as nitrogen, and a liquid such as water and oil.

The fluid-driven actuator can be used for various purposes, and can be used, for example, as a driving device for artificial muscles of nursing / welfare machines and medical machines, artificial muscles of robots, and indirect structures.

The silicone rubber-based curable composition of the present embodiment can be used to form a tube member in a fluid-driven actuator.

1 and 2 show an example of the configuration of a fluid-driven actuator (actuator 100).
The actuator 100 of FIG. 1 has a tube 10 and a cap 20.

The tube 10 is composed of a tubular elastic body that expands and contracts due to the pressure of a fluid. The tubular elastic body is composed of a cured product (silicone rubber) of the silicone rubber-based curable composition of the present embodiment.

The cap 20 is composed of a lid member provided at the axial end of the tube 10. The cap 20 may have the hole 22 shown in FIG. 2 (b). A fluid can be injected or discharged into the space 12 of the tube 10 through the hole 22. When the fluid is injected into the space 12, the tube 10 expands in the radial direction and contracts in the axial direction (FIGS. 2 (b) and 2 (c)). That is, the actuator 100 generates a contraction force in the axial direction and an expansion force in the radial direction of the tube 10.

The tube 10 can be enhanced in expansion durability against contact with other members in the actuator 100 or in the machine in which the actuator 100 is mounted. Therefore, the silicone rubber-based curable composition of the present embodiment can provide a tube member suitable for a fluid-driven actuator.

Further, the actuator 100 may have a tubular sleeve that covers the outer peripheral surface of the tube 10. The sleeve has a mesh-like reinforcing structure composed of fibers. The actuator 100 having the tube 10 and the sleeve becomes a Macchiben type artificial muscle.

By using the above-mentioned silicone rubber for the tube 10, expansion stability and expansion durability can be enhanced with respect to contact with the sleeve. Therefore, the silicone rubber-based curable composition of the present embodiment can provide a tube member suitable for a Macchiben type artificial muscle.

The details of the silicone rubber-based curable composition will be described below.

The stroke change rate after 1 hour of the cured product of the silicone rubber-based curable resin composition measured by the following procedure is SC1 (%), the stroke change rate after 5 hours is SC5 (%), and the tear strength. Let be TS (N / mm).

(Measurement procedure of stroke change rate)
Using the cured product of the silicone rubber-based curable composition, a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004), and when the chucks were held at a stress of 1 MPa, the temperature was 25 ° C. , The elongation of the obtained dumbbell-shaped No. 3 test piece is measured over time.
When the stress is 1 MPa, it is set to 0 h, and the stroke amount after a predetermined time n (h) is set to En (%) = [movement distance between chucks (mm)] ÷ [initial distance between chucks (60 mm)] × 100. The stroke change rate is calculated from the measured stroke amount from En based on the following formula.
Stroke change rate after n hours SCn (%) = (En-E0) / E0 × 100
(Measurement procedure of tear strength)
Using the cured product of the silicone rubber-based curable composition, a crescent-shaped test piece is prepared in accordance with JIS K6252 (2001), and the tear strength of the obtained crescent-shaped test piece is measured at 25 ° C. .. The unit is N / mm.

The upper limit of SC1 may be 50 or less, preferably 40 or less, and more preferably 30 or less. As a result, a silicone rubber having excellent expansion stability can be obtained. On the other hand, the lower limit of SC1 is not particularly limited, but may be 1 or more, or 2 or more. As a result, it is possible to realize a silicone rubber having an excellent balance between other characteristics such as mechanical strength and easy expandability.

The upper limit of SC5 may be 70 or less, preferably 50 or less, and more preferably 40 or less. As a result, a silicone rubber having excellent expansion stability can be obtained even during repeated expansion and long-term expansion. On the other hand, the lower limit of SC5 is not particularly limited, but may be 1 or more, or 3 or more. As a result, it is possible to realize a silicone rubber having an excellent balance between other characteristics such as mechanical strength and easy expandability.

The silicone rubber-based curable composition may have the property that SC1 and SC5 satisfy | SC5-SC1 | ≦ 20.
The upper limit of | SC5-SC1 | may be 20 or less, preferably 15 or less, and more preferably 10 or less. As a result, a silicone rubber having excellent expansion stability can be obtained even during repeated expansion and long-term expansion. On the other hand, the lower limit of | SC5-SC1 | is not particularly limited, but may be 1 or more. As a result, it is possible to realize a silicone rubber having an excellent balance with other characteristics.

The lower limit of the tear strength is, for example, 25 N / mm or more, preferably 28 N / mm or more, more preferably 30 N / mm or more, still more preferably 33 N / mm or more, still more preferably 35 N / mm or more. As a result, the durability of the silicone rubber during repeated use can be improved. In addition, the scratch resistance and mechanical strength of the silicone rubber can be improved. On the other hand, the upper limit of the tear strength is not particularly limited, but may be, for example, 80 N / mm or less, or 70 N / mm or less. Thereby, various characteristics of the silicone rubber can be balanced.

The durometer hardness A of the cured product of the silicone rubber-based curable resin composition is measured by the following procedure.
The upper limit of the durometer hardness A is not particularly limited, but may be, for example, 70 or less, preferably 55 or less, and more preferably 50 or less. This makes it possible to balance the cured physical properties of the silicone rubber. As a result, it is possible to enhance the deformability of the silicone rubber, which facilitates deformation such as bending and stretching.
On the other hand, the lower limit of the durometer hardness A is not particularly limited, but is, for example, 20 or more, preferably 25 or more, and more preferably 30 or more. As a result, the mechanical strength of the silicone rubber can be increased.

(Measurement procedure of durometer hardness A)
A sheet-shaped test piece was prepared using the cured product of the silicone rubber-based curable composition, and the durometer hardness A of the obtained sheet-shaped test piece at 25 ° C. was determined in accordance with JIS K6253 (1997). Measure.

The plasticity of the silicone rubber-based curable resin composition is measured by the following procedure.
The lower limit of plasticity is, for example, 80 or more, preferably 90 or more, and more preferably 100 or more. As a result, the manufacturing stability of extrusion molding using the silicone rubber-based curable composition can be enhanced. On the other hand, the upper limit of plasticity is, for example, 340 or less, preferably 320 or less, and more preferably 300 or less. As a result, the manufacturing stability of extrusion molding can be improved.

(Plasticizer measurement procedure)
About the plasticity of the obtained test sample at 25 ° C. using the uncured product of the silicone rubber-based curable composition as a test sample and using a Williams plasticity meter in accordance with JIS K6249 (2003). , Measure 10 minutes after the start of measurement.

In the present embodiment, for example, by appropriately selecting the type and blending amount of each component contained in the silicone rubber-based curable composition, the method for preparing the silicone rubber-based curable composition, and the like, the above hardness is obtained after 1 hour. It is possible to control the stroke change rate, the stroke change rate after 5 hours, the tear strength, and the plasticity. Among these, for example, the type and blending ratio of the resin constituting the silicone rubber, the crosslink density and the crosslinked structure of the resin, etc. are appropriately controlled, and the blending ratio of the inorganic filler and the dispersibility of the inorganic filler are improved. Etc. are mentioned as factors for setting the hardness, the stroke change rate after 1 hour, the stroke change rate after 5 hours, the tear strength, and the plasticity within a desired numerical range.

Next, the composition components of the silicone rubber-based curable composition will be described.

The silicone rubber-based curable composition of the present embodiment can contain a vinyl group-containing organopolysiloxane (A). The vinyl group-containing organopolysiloxane (A) is a polymer that is the main component of the silicone rubber-based curable composition.

The vinyl group-containing organopolysiloxane (A) can include a vinyl group-containing linear organopolysiloxane (A1) having a linear structure.

The vinyl group-containing linear organopolysiloxane (A1) has a linear structure and contains a vinyl group, and the vinyl group serves as a cross-linking point at the time of curing.

The content of the vinyl group of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is preferably, for example, having two or more vinyl groups in the molecule and 15 mol% or less. .. As a result, the amount of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1) is optimized, and a network with each component described later can be reliably formed.
In the present specification, "~" means that an upper limit value and a lower limit value are included unless otherwise specified.

In the present specification, the vinyl group content is the mol% of the vinyl group-containing siloxane unit when all the units constituting the vinyl group-containing linear organopolysiloxane (A1) are 100 mol%. .. However, it is considered that there is one vinyl group for each vinyl group-containing siloxane unit.

The degree of polymerization of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is preferably in the range of, for example, about 1000 to 10000, and more preferably about 2000 to 5000. The degree of polymerization can be determined, for example, as the polystyrene-equivalent number average degree of polymerization (or number average molecular weight) in GPC (gel permeation chromatography) using chloroform as a developing solvent.

Further, the specific gravity of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is preferably in the range of about 0.9 to 1.1.

By using a vinyl group-containing linear organopolysiloxane (A1) having a degree of polymerization and specific gravity within the above range, the obtained silicone rubber has heat resistance, flame retardancy, chemical stability, etc. Can be improved.

The vinyl group-containing linear organopolysiloxane (A1) preferably has a structure represented by the following formula (1).

In formula (1), R ¹ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an alkenyl group, an aryl group, or a hydrocarbon group in which these are combined. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group and the like, and among them, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, a butenyl group and the like, and among them, a vinyl group is preferable. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group and the like.

Further, R ² is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an alkenyl group, an aryl group, or a hydrocarbon group in which these are combined. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group and the like, and among them, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

Further, R ³ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group in which these are combined. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, a propyl group and the like, and among them, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group.

^{Further, examples of the substituent of R 1} and R ^{2 in} the formula (1) include a methyl group, a vinyl group and the like, and examples ^{of the substituent of R 3} include a methyl group and the like.

In the formula (1), a plurality of R ¹ is independent from each other, may be different from each other, it may be the same. The same applies to ^{R 2} and R ^3.

Further, m and n are the number of repeating units constituting the vinyl group-containing linear organopolysiloxane (A1) represented by the formula (1), m is an integer of 0 to 2000, and n is 1000 to 10000. Is an integer of. m is preferably 0 to 1000, and n is preferably 2000 to 5000.

Further, as a specific structure of the vinyl group-containing linear organopolysiloxane (A1) represented by the formula (1), for example, the one represented by the following formula (1-1) can be mentioned.

In formula (1-1), R ¹ and R ² are each independently a methyl group or a vinyl group, and at least one of them is a vinyl group.

The vinyl group-containing linear organopolysiloxane (A1) is a first vinyl group-containing linear compound having a vinyl group content of 2 or more in the molecule and 0.4 mol% or less. Organopolysiloxane (A1-1) may be included. The vinyl group amount of the first vinyl group-containing linear organopolysiloxane (A1-1) may be 0.1 mol% or less.

The vinyl group-containing linear organopolysiloxane (A1) has a vinyl group content of 0.5 to 15 mol% with the first vinyl group-containing linear organopolysiloxane (A1-1). May contain a vinyl group-containing linear organopolysiloxane (A1-2).

As raw rubber which is a raw material of silicone rubber, a first vinyl group-containing linear organopolysiloxane (A1-1) and a second vinyl group-containing linear organopolysiloxane (A1-2) having a high vinyl group content are used. ), The vinyl groups can be unevenly distributed, and the cross-linking density can be more effectively formed in the cross-linking network of the silicone rubber. As a result, the tear strength of the silicone rubber can be increased more effectively.

Specifically, as the vinyl group-containing linear organopolysiloxane (A1), for example, in the above formula (1-1), ^{a unit in which R 1} is a vinyl group and / or ^{a unit in which R 2} is a vinyl group is used. , A first vinyl group-containing linear organopolysiloxane (A1-1) having two or more in the molecule and containing 0.4 mol% or less, and ^{a unit in which R 1} is a vinyl group and / or R. ^It is preferable to use a second vinyl group-containing linear organopolysiloxane (A1-2) containing 0.5 to 15 mol% of the unit in which 2 is a vinyl group.

Further, the first vinyl group-containing linear organopolysiloxane (A1-1) preferably has a vinyl group content of 0.01 to 0.2 mol%. The vinyl group-containing linear organopolysiloxane (A1-2) preferably has a vinyl group content of 0.8 to 12 mol%.

Further, when the first vinyl group-containing linear organopolysiloxane (A1-1) and the second vinyl group-containing linear organopolysiloxane (A1-2) are blended in combination (A1-1). The ratio of and (A1-2) is not particularly limited, but for example, the weight ratio of (A1-1) :( A1-2) is preferably 50:50 to 95: 5, and 80:20 to 90: It is more preferably 10.

The first and second vinyl group-containing linear organopolysiloxanes (A1-1) and (A1-2) may be used alone or in combination of two or more. Good.

Further, the vinyl group-containing organopolysiloxane (A) may contain a vinyl group-containing branched organopolysiloxane (A2) having a branched structure.

<< Organohydrogen Polysiloxane (B) >>
The silicone rubber-based curable composition of the present embodiment can contain organohydrogenpolysiloxane (B).
Organohydrogenpolysiloxane (B) is classified into linear organohydrogenpolysiloxane (B1) having a linear structure and branched organohydrogenpolysiloxane (B2) having a branched structure. Either one or both can be included.

The linear organohydrogenpolysiloxane (B1) has a linear structure and a structure in which hydrogen is directly bonded to Si (≡Si—H), and is a vinyl group-containing organopolysiloxane (A). In addition to the vinyl group, it is a polymer that undergoes a hydrosilylation reaction with the vinyl group of the component blended in the silicone rubber-based curable composition to crosslink these components.

The molecular weight of the linear organohydrogenpolysiloxane (B1) is not particularly limited, but for example, the weight average molecular weight is preferably 20000 or less, and more preferably 1000 or more and 10000 or less.

The weight average molecular weight of the linear organohydrogenpolysiloxane (B1) can be measured, for example, by polystyrene conversion in GPC (gel permeation chromatography) using chloroform as a developing solvent.

Further, the linear organohydrogenpolysiloxane (B1) usually preferably has no vinyl group. As a result, it is possible to accurately prevent the cross-linking reaction from proceeding in the molecule of the linear organohydrogenpolysiloxane (B1).

As the linear organohydrogenpolysiloxane (B1) as described above, for example, one having a structure represented by the following formula (2) is preferably used.

In the formula (2), R ⁴ is a hydrocarbon group or a hydride group, in combination a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an alkenyl group, an aryl group, these. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group and the like, and among them, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, a butenyl group and the like. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

Also, R ⁵ is a hydrocarbon group or a hydride group, in combination a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an alkenyl group, an aryl group, these. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group and a propyl group, and among them, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, a butenyl group and the like. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

In the formula (2), a plurality of R ⁴ are independent from each other, may be different from each other, it may be the same. The same is true for R ^5. However, of the plurality of R ⁴ and R ⁵ , at least two or more are hydride groups.

Further, R ⁶ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group in which these are combined. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, a propyl group and the like, and among them, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. A plurality of R ⁶ are independent from each other, may be different from each other, it may be the same.

^{Examples of the substituent of R 4} , R ⁵ , and R ^{6 in} the formula (2) include a methyl group and a vinyl group, and a methyl group is preferable from the viewpoint of preventing an intramolecular cross-linking reaction.

Further, m and n are the number of repeating units constituting the linear organohydrogenpolysiloxane (B1) represented by the formula (2), where m is an integer of 2 to 150 and n is an integer of 2 to 150. Is. Preferably, m is an integer of 2 to 100 and n is an integer of 2 to 100.

The linear organohydrogenpolysiloxane (B1) may be used alone or in combination of two or more.

Since the branched organohydrogenpolysiloxane (B2) has a branched structure, it forms a region having a high crosslink density and is a component that greatly contributes to the formation of a sparsely packed structure with a crosslink density in the silicone rubber system. Further, like the linear organohydrogenpolysiloxane (B1), it has a structure (≡Si—H) in which hydrogen is directly bonded to Si, and in addition to the vinyl group of the vinyl group-containing organopolysiloxane (A), silicone. It is a polymer that hydrosilylates with the vinyl group of the component contained in the rubber-based curable composition and crosslinks these components.

The specific gravity of the branched organohydrogenpolysiloxane (B2) is in the range of 0.9 to 0.95.

Further, the branched organohydrogenpolysiloxane (B2) usually preferably has no vinyl group. As a result, it is possible to accurately prevent the cross-linking reaction from proceeding in the molecule of the branched organohydrogenpolysiloxane (B2).

Further, as the branched organohydrogenpolysiloxane (B2), those represented by the following average composition formula (c) are preferable.

Average composition formula (c)
^{_{(H a (R 7) 3}} -a SiO 1/2) m (SiO 4/2) n
(In the formula (c), ^{R 7} is a monovalent organic group, a is 1 to 3 in the range of integers, m is ^{_{H a (R 7) 3-}} a number of _{SiO 1/2} units, n represents SiO _{4 /} It is a number of _{2 units)}

In formula (c), R ⁷ is a monovalent organic group, preferably a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an aryl group, or a hydrocarbon group in combination thereof. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group and the like, and among them, a methyl group is preferable. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

In the formula (c), a is the number of hydride groups (hydrogen atoms directly bonded to Si), and is an integer in the range of 1 to 3, preferably 1.

Further, in the equation (c), m is ^{_{H a (R 7) 3-}} a number of _{SiO 1/2} units, n is the number of _{SiO 4/2} units.

The branched organohydrogenpolysiloxane (B2) has a branched structure. The linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) differ in that their structures are linear or branched, and are different from Si when the number of Si is 1. The number of alkyl groups R to be bonded (R / Si) is 1.8 to 2.1 for the linear organohydrogenpolysiloxane (B1) and 0.8 to 1 for the branched organohydrogenpolysiloxane (B2). It is in the range of 0.7.

Since the branched organohydrogenpolysiloxane (B2) has a branched structure, for example, the amount of residue when heated to 1000 ° C. at a heating rate of 10 ° C./min under a nitrogen atmosphere is 5% or more. It becomes. On the other hand, since the linear organohydrogenpolysiloxane (B1) is linear, the amount of residue after heating under the above conditions is almost zero.

Further, as a specific example of the branched organohydrogenpolysiloxane (B2), those having a structure represented by the following formula (3) can be mentioned.

In formula (3), R ⁷ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group combining these, or a hydrogen atom. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, a propyl group and the like, and among them, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. Examples of the substituent of R ⁷ include a methyl group and the like.

In the equation (3), the plurality of R ^7s are independent of each other and may be different from each other or may be the same.

Further, in the equation (3), "-O-Si≡" indicates that Si has a branched structure that spreads three-dimensionally.

The branched organohydrogenpolysiloxane (B2) may be used alone or in combination of two or more.

Further, in the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2), the amount of hydrogen atoms (hydride groups) directly bonded to Si is not particularly limited. However, in the silicone rubber-based curable composition, the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpoly are added to 1 mol of the vinyl group in the vinyl group-containing linear organopolysiloxane (A1). The total amount of hydride groups of siloxane (B2) is preferably 0.5 to 5 mol, more preferably 1 to 3.5 mol. This ensures that a crosslinked network is formed between the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) and the vinyl group-containing linear organopolysiloxane (A1). Can be made to.

<< Silica particles (C) >>
The silicone rubber-based curable composition of the present embodiment may contain silica particles (C) in addition to the vinyl group-containing polyorganosiloxane (A).

The silica particles (C) are not particularly limited, but for example, fumed silica, calcined silica, precipitated silica and the like are used. These may be used alone or in combination of two or more.

The specific surface area of the silica particles (C) according to the BET method ^{is preferably, for example, 50 to 400 m 2} / g, and more preferably 100 to 400 m ² / g. The average primary particle size of the silica particles (C) is preferably, for example, 1 to 100 nm, and more preferably about 5 to 20 nm.

By using the silica particles (C) within the range of the specific surface area and the average particle size, it is possible to improve the hardness and mechanical strength of the formed silicone rubber, particularly the tensile strength.

<< Silane Coupling Agent (D) >>
The silicone rubber-based curable composition of the present embodiment can contain a silane coupling agent (D).
The silane coupling agent (D) can have a hydrolyzable group. The hydrolyzing group is hydrolyzed by water to become a hydroxyl group, and this hydroxyl group undergoes a dehydration condensation reaction with the hydroxyl group on the surface of the silica particles (C), whereby the surface of the silica particles (C) can be modified.

Further, the silane coupling agent (D) can include a silane coupling agent having a hydrophobic group. As a result, this hydrophobic group is imparted to the surface of the silica particles (C), so that the cohesive force of the silica particles (C) is reduced in the silicone rubber-based curable composition and thus in the silicone rubber (hydrogen due to silanol groups). Aggregation due to bonding is reduced), and as a result, it is presumed that the dispersibility of silica particles in the silicone rubber-based curable composition is improved. As a result, the interface between the silica particles and the rubber matrix is increased, and the reinforcing effect of the silica particles is increased. Further, it is presumed that the slipperiness of the silica particles in the matrix is improved when the rubber matrix is deformed. Then, by improving the dispersibility and slipperiness of the silica particles (C), the mechanical strength (for example, tensile strength, tear strength, etc.) of the silicone rubber due to the silica particles (C) is improved.

Further, the silane coupling agent (D) can include a silane coupling agent having a vinyl group. As a result, a vinyl group is introduced on the surface of the silica particles (C). Therefore, when the silicone rubber-based curable composition is cured, that is, the vinyl group contained in the vinyl group-containing organopolysiloxane (A) and the hydride group contained in the organohydrogenpolysiloxane (B) undergo a hydrosilylation reaction. When the network (crosslinked structure) formed by these is formed, the vinyl group of the silica particles (C) is also involved in the hydrosilylation reaction with the hydride group of the organohydrogenpolysiloxane (B). Silica particles (C) will also be incorporated into the siloxane. As a result, it is possible to reduce the hardness and increase the modulus of the formed silicone rubber.

As the silane coupling agent (D), a silane coupling agent having a hydrophobic group and a silane coupling agent having a vinyl group can be used in combination.

Examples of the silane coupling agent (D) include those represented by the following formula (4).

Y _n- Si- (X) _4-n ... (4)
In the above equation (4), n represents an integer of 1 to 3. Y represents any functional group having a hydrophobic group, a hydrophilic group or a vinyl group, and when n is 1, it is a hydrophobic group, and when n is 2 or 3, at least one of them is. It is a hydrophobic group. X represents a hydrolyzable group.

The hydrophobic group is an alkyl group having 1 to 6 carbon atoms, an aryl group, or a hydrocarbon group in which these are combined, and examples thereof include a methyl group, an ethyl group, a propyl group, a phenyl group, and the like. Methyl groups are preferred.

Examples of the hydrophilic group include a hydroxyl group, a sulfonic acid group, a carboxyl group, a carbonyl group and the like, and among them, a hydroxyl group is particularly preferable. The hydrophilic group may be contained as a functional group, but is preferably not contained from the viewpoint of imparting hydrophobicity to the silane coupling agent (D).

Further, examples of the hydrolyzable group include an alkoxy group such as a methoxy group and an ethoxy group, a chloro group or a silazane group, and among them, a silazane group is preferable because it has high reactivity with the silica particles (C). Those having a silazane group as a hydrolyzable group have _{two structures of (Y n −} Si−) in the above formula (4) due to their structural characteristics.

Specific examples of the silane coupling agent (D) represented by the above formula (4) include, for example, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, and methyltri as those having a hydrophobic group as a functional group. Ekoxysilanes such as ethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane; methyltrichlorosilane , Dimethyldichlorosilane, trimethylchlorosilane, chlorosilanes such as phenyltrichlorosilane; hexamethyldisilazane, examples of which have a vinyl group as a functional group include methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxy. Ekoxysilanes such as propylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane, vinylmethyldichlorosilane; divinyltetramethyldi Examples thereof include silazan, but in consideration of the above description, hexamethyldisilazane is particularly preferable as having a hydrophobic group, and divinyltetramethyldisilazane is preferable as having a vinyl group.

<< Platinum or platinum compound (E) >>
The silicone rubber-based curable composition of the present embodiment can contain platinum or a platinum compound (E).
Platinum or the platinum compound (E) is a catalytic component that acts as a catalyst during curing. The amount of platinum or platinum compound (E) added is the amount of catalyst.

As the platinum or the platinum compound (E), known ones can be used, for example, platinum black, platinum supported on silica, carbon black or the like, platinum chloride acid or an alcohol solution of platinum chloride acid, chloride. Examples thereof include a complex salt of platinum acid and olefin, and a complex salt of platinum chloride acid and vinyl siloxane.

As the platinum or the platinum compound (E), only one type may be used alone, or two or more types may be used in combination.

<< Water (F) >>
Further, the silicone rubber-based curable composition of the present embodiment may contain water (F) in addition to the above components (A) to (E).

Water (F) functions as a dispersion medium for dispersing each component contained in the silicone rubber-based curable composition, and is a component that contributes to the reaction between the silica particles (C) and the silane coupling agent (D). .. Therefore, in the silicone rubber, the silica particles (C) and the silane coupling agent (D) can be more reliably connected to each other, and uniform characteristics can be exhibited as a whole.

Further, the silicone rubber-based curable composition of the present embodiment may contain known additive components to be blended in the silicone rubber-based curable composition in addition to the above-mentioned components (A) to (F). For example, diatomaceous earth, iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide, cerium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, glass wool, mica and the like can be mentioned. In addition, dispersants, pigments, dyes, antistatic agents, antioxidants, flame retardants, thermal conductivity improvers and the like can be appropriately blended.

In the silicone rubber-based curable composition, the content ratio of each component is not particularly limited, but is set as follows, for example.

In the present embodiment, the upper limit of the content of the silica particles (C) may be, for example, 60 parts by weight or less, preferably 50 parts by weight, based on 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). It may be less than or equal to, and more preferably 40 parts by weight or less. As a result, it is possible to balance mechanical strength such as hardness and tensile strength. The lower limit of the content of the silica particles (C) is not particularly limited with respect to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A), but may be, for example, 10 parts by weight or more.

The silane coupling agent (D) is preferably contained in a proportion of, for example, 5 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the vinyl group-containing organopolysiloxane (A). More preferably, it is contained in a proportion of 5 parts by weight or more and 40 parts by weight or less. Thereby, the dispersibility of the silica particles (C) in the silicone rubber-based curable composition can be surely improved.

The content of the organohydrogenpolysiloxane (B) is specifically, for example, with respect to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A), the silica particles (C) and the silane coupling agent (D). , 0.5 part by weight or more and preferably 20 parts by weight or less, and more preferably 0.8 parts by weight or more and 15 parts by weight or less. When the content of (B) is within the above range, a more effective curing reaction may be possible.

The content of platinum or the platinum compound (E) means the amount of the catalyst and can be appropriately set. Specifically, the vinyl group-containing organopolysiloxane (A), the silica particles (C), and the silane coupling agent ( The amount of the platinum group metal in this component is 0.01 to 1000 ppm, preferably 0.1 to 500 ppm, based on the total amount of D). By setting the content of platinum or the platinum compound (E) to the above lower limit value or more, the obtained silicone rubber composition can be sufficiently cured. By setting the content of platinum or the platinum compound (E) to the above upper limit value or less, the curing rate of the obtained silicone rubber composition can be improved.

Further, when water (F) is contained, the content thereof can be appropriately set. Specifically, for example, 10 to 100 parts by weight with respect to 100 parts by weight of the silane coupling agent (D). It is preferably in the range of 30 to 70 parts by weight, and more preferably in the range of 30 to 70 parts by weight. As a result, the reaction between the silane coupling agent (D) and the silica particles (C) can proceed more reliably.

<Manufacturing method of silicone rubber>
Next, the method for producing the silicone rubber of the present embodiment will be described.
As a method for producing a silicone rubber of the present embodiment, a silicone rubber-based curable composition is prepared, and the silicone rubber-based curable composition is cured to obtain a silicone rubber.
The details will be described below.

First, each component of the silicone rubber-based curable composition is uniformly mixed by an arbitrary kneading device to prepare a silicone rubber-based curable composition.

[1] For example, a vinyl group-containing organopolysiloxane (A), silica particles (C), and a silane coupling agent (D) are weighed in a predetermined amount, and then kneaded by an arbitrary kneading device. A kneaded product containing each of these components (A), (C), and (D) is obtained.

The kneaded product is preferably obtained by kneading the vinyl group-containing organopolysiloxane (A) and the silane coupling agent (D) in advance, and then kneading (mixing) the silica particles (C). As a result, the dispersibility of the silica particles (C) in the vinyl group-containing organopolysiloxane (A) is further improved.

Further, when obtaining this kneaded product, water (F) may be added to the kneaded product of each component (A), (C), and (D), if necessary. As a result, the reaction between the silane coupling agent (D) and the silica particles (C) can proceed more reliably.

Further, it is preferable that the kneading of each component (A), (C), and (D) goes through a first step of heating at the first temperature and a second step of heating at the second temperature. Thereby, in the first step, the surface of the silica particles (C) can be surface-treated with the coupling agent (D), and in the second step, the silica particles (C) and the coupling agent (D) are combined. By-products produced by the reaction can be reliably removed from the kneaded product. Then, if necessary, the component (A) may be added to the obtained kneaded product and further kneaded. Thereby, the familiarity of the components of the kneaded product can be improved.

The first temperature is preferably, for example, about 40 to 120 ° C., and more preferably about 60 to 90 ° C., for example. The second temperature is preferably, for example, about 130 to 210 ° C., and more preferably about 160 to 180 ° C., for example.

The atmosphere in the first step is preferably an inert atmosphere such as a nitrogen atmosphere, and the atmosphere in the second step is preferably a reduced pressure atmosphere.

Further, the time of the first step is preferably, for example, about 0.3 to 1.5 hours, and more preferably about 0.5 to 1.2 hours. The time of the second step is, for example, preferably about 0.7 to 3.0 hours, and more preferably about 1.0 to 2.0 hours.

By setting the first step and the second step under the above-mentioned conditions, the effect can be obtained more remarkably.

[2] Next, the organohydrogenpolysiloxane (B) and platinum or the platinum compound (E) are weighed in a predetermined amount, and then the kneaded product prepared in the above step [1] using an arbitrary kneading device. , Each component (B) and (E) is kneaded to obtain a silicone rubber-based curable composition. The obtained silicone rubber-based curable composition may be a paste containing a solvent.

When kneading the respective components (B) and (E), the kneaded product previously prepared in the above step [1] and the organohydrogenpolysiloxane (B) were prepared in the above step [1]. It is preferable to knead the kneaded product with platinum or the platinum compound (E), and then knead the respective kneaded products. As a result, each component (A) to (E) is surely contained in the silicone rubber-based curable composition without proceeding the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B). Can be dispersed in.

The temperature at which the respective components (B) and (E) are kneaded is preferably, for example, about 10 to 70 ° C., and more preferably about 25 to 30 ° C. as the roll set temperature.

Further, the kneading time is preferably, for example, about 5 minutes to 1 hour, and more preferably about 10 to 40 minutes.

By setting the temperature within the above range in the above step [1] and the above step [2], the progress of the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) can be made more accurate. Can be prevented or suppressed. Further, in the above steps [1] and [2], by setting the kneading time within the above range, each component (A) to (E) is more reliably dispersed in the silicone rubber-based curable composition. Can be done.

The kneading device used in each of the steps [1] and [2] is not particularly limited, and for example, a kneader, two rolls, a Banbury mixer (continuous kneader), a pressurized kneader, or the like can be used.

Further, in this step [2], a reaction inhibitor such as 1-ethynylcyclohexanol may be added to the kneaded product. As a result, even if the temperature of the kneaded product is set to a relatively high temperature, the progress of the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) is more accurately prevented or suppressed. be able to.

[3] Next, a silicone rubber is formed by curing the silicone rubber-based curable composition.

In the present embodiment, the curing step of the silicone rubber-based curable resin composition is, for example, heating at 100 to 250 ° C. for 1 to 30 minutes (primary curing) and then post-baking (secondary) at 200 ° C. for 1 to 4 hours. It is done by curing).
By going through the above steps, a silicone rubber can be obtained by using the silicone rubber-based curable resin composition of the present embodiment.

The fluid-driven actuator (actuator 100) of the present embodiment includes a tube member formed of a cured product of a silicone rubber-based curable composition.

The actuator 100 may have one or more tubes 10 in the axial direction.

As a method for producing the tube 10, a method of forming a tube-shaped silicone rubber by extrusion molding using a silicone rubber-based curable composition or a method of forming a tube-shaped silicone rubber by compression molding may be used. ..

The tube 10 may have a tubular structure extending in the axial direction, or may have a curved structure in which all or part of the tube 10 is curved.

The tube 10 may have one or more spaces 12 inside. Specifically, the tube 10 may have a plurality of divided spaces 12 by one or more rings or by adhering the inner surfaces of the silicone rubber layers to each other. The plurality of spaces 12 are arranged so as to be arranged in the axial direction of the tube 10.

The silicone rubber layer of the tube 10 may be a single layer or may be composed of two or more layers. Each silicone rubber layer may be composed of one kind or two or more kinds of silicone rubber layers. For example, a fiber layer may be provided between the two silicone rubber layers. Further, the tube 10 may have at least a part of two or more silicone rubber layers having different expansion / contraction ratios or a layer other than silicone rubber.

The cap 20 may be installed on the inner peripheral surface of the tube 10, but may be installed on the outer peripheral surface of the tube 10. The cap 20 may have a connecting mechanism for connecting with another mechanism or member.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the description of these Examples.

The raw material components used in the examples and comparative examples shown in Table 1 are shown below.
(Vinyl group-containing organopolysiloxane (A))
-Low vinyl group-containing linear organopolysiloxane (A1-1): Vinyl group-containing dimethylpolysiloxane synthesized by Synthesis Scheme 1 (structure represented by formula (1-1), ^{only R 1} (terminal) is a vinyl group. Structure)
High-vinyl group-containing linear organopolysiloxane (A1-2): Vinyl group-containing dimethylpolysiloxane synthesized by Synthesis Scheme 3 (in the structure represented by the formula (1-1), R ¹ and R ² are vinyl groups. A certain structure)
-Low vinyl group-containing linear organopolysiloxane (A1-3): Vinyl group-containing dimethylpolysiloxane synthesized by Synthesis Scheme 3 (in the structure represented by the formula (1-1), R ¹ and R ² are vinyl groups. A certain structure)

(Organohydrogenpolysiloxane (B))
-Made by Momentive: "TC-25D"

(Silica particles (C))
-Silica particles (C-1): silica fine particles (particle size 7 nm, specific surface area 300 m ² / g), manufactured by Nippon Aerosil Co., Ltd., "AEROSIL300"
-Silica particles (C-2): silica fine particles (particle size 16 nm, specific surface area 110 m ² / g), manufactured by Nippon Aerosil Co., Ltd., "AEROSIL R972"

(Silane Coupling Agent (D))
-Silane coupling agent (D-1): Hexamethyldisilazane (HMDZ), manufactured by Gelest, "HEXAMETHYLDISILAZANE (SIH6110.1)"
-Silane coupling agent (D-2): Divinyltetramethyldisilazane, manufactured by Gelest, "1,3-DIVINYLTETRAMETHYLDISILAZANE (SID4612.0)"

(Platinum or platinum compound (E))
-Made by Momentive: "TC-25A"

(Synthesis of vinyl group-containing organopolysiloxane (A))
[Synthesis scheme 1: Synthesis of linear organopolysiloxane (A1-1) containing low vinyl group]
A low vinyl group-containing linear organopolysiloxane (A1-1) was synthesized according to the following formula (5).
That is, 74.7 g (252 mmol) of octamethylcyclotetrasiloxane and 0.1 g of potassium silicate were placed in a 300 mL separable flask having a cooling tube and a stirring blade substituted with Ar gas, the temperature was raised, and the temperature was raised at 120 ° C. for 30 minutes. Stirred. At this time, an increase in viscosity was confirmed.
Then, the temperature was raised to 155 ° C., and stirring was continued for 3 hours. Then, after 3 hours, 0.1 g (0.6 mmol) of 1,3-divinyltetramethyldisiloxane was added, and the mixture was further stirred at 155 ° C. for 4 hours.
After 4 hours, the mixture was diluted with 250 mL of toluene and washed 3 times with water. The organic layer after washing was washed several times with 1.5 L of methanol to reprecipitate and separate the oligomer and the polymer. The resulting polymer was dried under reduced pressure overnight at 60 ° C., to obtain a low vinyl-containing linear organopolysiloxane (A1-1) (Mn = 2,2 × 10 5, Mw = 4,8 × 10 5 ). The vinyl group content calculated by 1 H-NMR spectrum measurement was 0.04 mol%.

[Synthesis scheme 2: Synthesis of linear organopolysiloxane (A1-2) containing high vinyl group]
In the synthesis step of (A1-1) above, in addition to 74.7 g (252 mmol) of octamethylcyclotetrasiloxane, 2,4,6,8-tetramethyl 2,4,6,8-tetravinylcyclotetrasiloxane 0. By performing the same as the synthesis step of (A1-1) except that 86 g (2.5 mmol) was used, a high vinyl group-containing linear organopolysiloxane (A1-) was used as shown in the following formula (6). 2) was synthesized. ^{(Mn = 2,3 × 10 5,} Mw = 5,0 × 10 5). The vinyl group content calculated by 1 H-NMR spectrum measurement was 0.93 mol%.

[Synthesis scheme 3: Synthesis of linear organopolysiloxane (A1-3) containing low vinyl group]
In the synthesis step of (A1-2) above, 75.3 g (254 mmol) of octamethylcyclotetrasiloxane, 0.12 g of 2,4,6,8-tetramethyl 2,4,6,8-tetravinylcyclotetrasiloxane (0.12 g). 0.35 mmol) was used, and the stirring time after raising the temperature to 155 ° C. was set to 3 hours. A linear organopolysiloxane (A1-3) containing a low vinyl group was synthesized. ^{(Mn = 2.5 × 10 5,} Mw = 5.0 × 10 5). The vinyl group content calculated by 1 H-NMR spectrum measurement was 0.13 mol%.

(Examples 1 to 5, Comparative Example 1: Preparation of silicone rubber-based curable composition)
The silicone rubber-based curable composition was prepared as follows.
First, a mixture of 90% vinyl group-containing organopolysiloxane (A), silane coupling agent (D) and water (F) is kneaded in advance at the ratio shown in Table 1 below, and then silica particles (silica particles (A)) are added to the mixture. C) was added and further kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after the addition of the silica particles (C) is carried out in the first step of kneading for 1 hour under the condition of 60 to 90 ° C. under a nitrogen atmosphere for the coupling reaction, and removal of the by-product (ammonia). Therefore, it is carried out by going through the second step of kneading for 2 hours under the condition of 160 to 180 ° C. under a reduced pressure atmosphere, and then cooling, and the remaining 10% of the vinyl group-containing organopolysiloxane (A) is added twice. It was added separately and kneaded for 20 minutes.
Subsequently, 100 parts by weight of the obtained kneaded product (silicone rubber compound) was added with organohydrogenpolysiloxane (B) (TC-25D) and platinum or platinum compound (E) (TC) in the proportions shown in Table 1 below. -25A) was added and kneaded with a roll to obtain a silicone rubber-based curable composition.

(Comparative Example 2: Preparation of Silicone Rubber Curable Composition)
The vinyl group-containing organopolysiloxane (A) is kneaded alone for 5 minutes at the ratio shown in Table 1 below, then silica particles (C) are added to the mixture and kneaded for another 2 hours, and the kneaded product (silicone rubber) is kneaded. Compound) was obtained.
Subsequently, 100 parts by weight of the obtained kneaded product (silicone rubber compound) was added with organohydrogenpolysiloxane (B) (TC-25D) and platinum or platinum compound (E) (TC) in the proportions shown in Table 1 below. -25A) was added and kneaded with a roll to obtain a silicone rubber-based curable composition.

(Making silicone rubber for evaluation)
In Examples 1 and 2 and Comparative Examples 1 and 2, the obtained silicone rubber-based curable composition was pressed at 170 ° C. and 10 MPa for 10 minutes to form a sheet having a thickness of 1 mm and first cured. .. Subsequently, it was heated at 200 ° C. for 4 hours and secondarily cured. From the above, a sheet-shaped silicone rubber (a cured product of a silicone rubber-based curable composition) was obtained.

The obtained sheet-shaped silicone rubber (sheet-shaped elastomer) was evaluated based on the following evaluation items.
The stroke change rate after 1 hour and the stroke change rate after 5 hours were measured with three samples, and the average value of the three was used as the measured value.
The tear strength was measured with 5 samples, and the average value of 5 was used as the measured value.
The hardness was measured using two samples at n = 5 in each sample, and the average value of a total of 10 measurements was taken as the measured value. The average value of each is shown in Table 2.

<Hardness: Durometer hardness>
Six sheets of the obtained sheet-shaped silicone rubber having a thickness of 1 mm were laminated to prepare a test piece having a thickness of 6 mm. The hardness of the obtained test piece was measured at 25 ° C. according to JIS K6253 (1997). ..

<Tear strength>
Using the obtained sheet-shaped silicone rubber having a thickness of 1 mm, a crescent-shaped test piece was prepared in accordance with JIS K6252 (2001), and the obtained crescent-shaped test piece was subjected to tear strength (TS) at 25 ° C. Was measured. The unit is N / mm.

<Stroke change rate after 1 hour (SC1)> Stroke change rate after 5 hours (SC5)>
Using the obtained sheet-shaped silicone rubber with a thickness of 1 mm, a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004), and pulled until a stress of 1 MPa was reached at 25 ° C. thereafter. The elongation of the obtained dumbbell-shaped No. 3 test piece when the stress of 1 MPa was maintained was measured over time.
When the stress becomes 1 MPa, it is set to 0 h, and the stroke amount after a predetermined time n (h) is set to En (%) = [movement distance between chucks (mm)] ÷ [initial distance between chucks (60 mm)] × 100. The stroke change rate was calculated from the measured stroke amount from En based on the following formula.
Stroke change rate after n hours SCn (%) = (En-E0) / E0 × 100
Here, the stroke change rate of n = 1 (h) and 5 (h) was calculated.

<Plasticity>
The uncured product of the obtained silicone rubber-based curable composition was used as a test sample.
The plasticity of the test sample at 25 ° C. was measured using a Williams plasticity meter (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) in accordance with JIS K6249 (2003). The values 10 minutes after the start of measurement are shown in Table 2 as the plasticity.

(Manufacturing of tube members)
Using the silicone rubber-based curable compositions of each Example and Comparative Example, they were extruded into a tube shape using an extruder to obtain a tube member.

<Expansion stability>
1 MPa of air was injected into the obtained tube member, the expansion was maintained for 30 minutes, and then the air was discharged. After repeating this expansion operation 10 times, the radial lengths of the tube members during the first expansion and the 10th expansion were compared. It was found that the tube members of Examples 1 to 6 had a smaller rate of change in length in the radial direction than that of Comparative Example 1.

<Expansion durability>
Air was injected into the space from the ends of the tube members obtained in Examples 1 to 5 and Comparative Example 2, and radial expansion was repeated a predetermined number of times. In Comparative Example 2, after repeated expansion a predetermined number of times, some damage was observed during expansion, but in Examples 1 to 5, no damage was observed in the tube member even after repeated expansion.

The silicone rubber-based curable compositions of Examples 1 to 5 showed excellent results in easy expansion as compared with Comparative Example 1. Further, it was found that the tube member formed by using the silicone rubber-based curable composition of Examples 1 to 5 was superior in durability to repeated expansion by air as compared with Comparative Example 2. Such a silicone rubber-based curable composition can be suitably used for a fluid-driven actuator.

10 Tube 12 Space 20 Cap 22 Hole 100 Actuator

Claims (9)

A silicone rubber-based curable composition used to form a part constituting a fluid-driven actuator.
When the stroke change rate after 1 hour of the cured product of the silicone rubber-based curable resin composition measured by the following procedure is SC1 (%) and the tear strength is TS (N / mm).
A silicone rubber-based curable composition in which SC1 and TS satisfy SC1 ≦ 50 and 20 ≦ TS.
(Measurement procedure of stroke change rate)
Using the cured product of the silicone rubber-based curable composition, a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004), and when the chucks were held at a stress of 1 MPa, the temperature was 25 ° C. , The elongation of the obtained dumbbell-shaped No. 3 test piece is measured over time.
When the stress is 1 MPa, it is set to 0 h, and the stroke amount after a predetermined time n (h) is set to En (%) = [movement distance between chucks (mm)] ÷ [initial distance between chucks (60 mm)] × 100. The stroke change rate is calculated from the measured stroke amount from En based on the following formula.
Stroke change rate after n hours SCn (%) = (En-E0) / E0 × 100
(Measurement procedure of tear strength)
Using the cured product of the silicone rubber-based curable composition, a crescent-shaped test piece is prepared in accordance with JIS K6252 (2001), and the tear strength of the obtained crescent-shaped test piece is measured at 25 ° C. .. The unit is N / mm. The silicone rubber-based curable composition according to claim 1.
When the stroke change rate after 5 hours of the cured product of the silicone rubber-based curable resin composition measured by the above procedure is SC5 (%).
A silicone rubber-based curable composition in which SC5 satisfies SC5 ≦ 70. The silicone rubber-based curable composition according to claim 2.
A silicone rubber-based curable composition in which SC1 and SC5 satisfy | SC5-SC1 | ≤20. The silicone rubber-based curable composition according to any one of claims 1 to 3.
A silicone rubber-based curable composition having a durometer hardness A of 20 or more and 70 or less of the cured product of the silicone rubber-based curable resin composition measured by the following procedure.
(Measurement procedure of durometer hardness A)
A sheet-shaped test piece was prepared using the cured product of the silicone rubber-based curable composition, and the durometer hardness A of the obtained sheet-shaped test piece at 25 ° C. was determined in accordance with JIS K6253 (1997). Measure. The silicone rubber-based curable composition according to any one of claims 1 to 4.
A silicone rubber-based curable composition having a plasticity of 80 to 340, which is measured by the following procedure.
(Plasticizer measurement procedure)
About the plasticity of the obtained test sample at 25 ° C. using the uncured product of the silicone rubber-based curable composition as a test sample and using a Williams plasticity meter in accordance with JIS K6249 (2003). , Measure 10 minutes after the start of measurement. The silicone rubber-based curable composition according to any one of claims 1 to 5.
Vinyl group-containing polyorganosiloxane (A) and
A silicone rubber-based curable composition containing silica particles (C). The silicone rubber-based curable composition according to claim 6.
A silicone rubber-based curable composition in which the content of the silica particles (C) is 10 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the vinyl group-containing polyorganosiloxane (A). The silicone rubber-based curable composition according to any one of claims 1 to 7.
A silicone rubber-based curable composition used for forming a tube member in the fluid-driven actuator. A fluid-driven actuator comprising a tube member formed of a cured product of the silicone rubber-based curable composition according to any one of claims 1 to 8.

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