JP2021116363A - Silicone rubber-based curable composition and fluid-driven actuator - Google Patents

Abstract

To provide a silicone rubber-based curable composition excellent in extension durability and friction durability.SOLUTION: The silicone rubber-based curable composition of the present invention is used for forming a part constituting a fluid-driven actuator. When the tensile stress at 30% elongation and the tensile stress at 300% elongation of a cured product of the silicone rubber-based curable composition are M30 and M300 respectively, M30 and M300 satisfy 0.25≤M30/M300≤1.0.SELECTED DRAWING: None

Description

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

Various developments have been made on silicone rubber used to form a part of a movable member constituting an actuator or the like. 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 examination by the present inventor, it has been found that the silicone rubber described in Patent Document 1 has room for improvement in terms of elongation durability and friction durability.

As a result of further studies, the present inventor has found that the elongation durability and the friction durability can be controlled by appropriately adjusting the 30% modulus and the 300% modulus of the silicone rubber-based curable composition.
As a result of further diligent research based on these findings, it is possible to stably evaluate elongation durability and friction durability by using _{the ratio of 30% modulus to 300% modulus (M 30} / M _{300) as an index.} It was found _{that by setting the index M 30} / M ₃₀₀ to a predetermined value or more, it is possible to realize a silicone rubber which is excellent in elongation durability and friction durability and which 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.
Is measured by the following procedures, when the cured product of the silicone rubber based curable composition, the tensile stress of the tensile stress at 30% elongation during M _30, 300% elongation was M _300,
M ₃₀ and M ₃₀₀ satisfy 0.25 ≤ M ₃₀ / M ₃₀₀ ≤ 1.0.
A silicone rubber-based curable composition is provided.
(Procedure for measuring tensile stress)
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 the obtained dumbbell-shaped No. 3 test piece was obtained at 25 ° C. The tensile stress at 30% and 300% elongation is measured.

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 elongation durability and friction 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 cross-sectional view taken along the line AA of FIG. 1, (b) is a cross-sectional view taken along the line BB 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, it is measured in the following procedure, the cured product of the silicone rubber based curable composition, the tensile stress of the tensile stress at 30% elongation during M _30, 300% elongation When M ₃₀₀ is set, M ₃₀ and M ₃₀₀ satisfy 0.25 ≦ M ₃₀ / M ₃₀₀ ≦ 1.0.

It is known that in ordinary silicone rubber, if the composition is adjusted so that the 300% modulus is low, the hardness is also lowered, while if the composition is adjusted so that the hardness is high, the 300% modulus is also high.

On the other hand, as described later, the present inventor has increased the molecular weight between the cross-linking points and the bond between the rubber and the filler in the silicone rubber-based curable composition to increase the hardness and 30% modulus. It was found that the 300% modulus can be kept low while increasing the value.
Then, by using the ratio of 30% modulus to 300% modulus (M ₃₀ / M ₃₀₀ ) as an index, it becomes possible to stably evaluate the elongation durability and the friction durability, which is an index M ₃₀ /. It _{has been found that by setting the M 300} to the above upper limit value or more, it is possible to realize a silicone rubber which is excellent in elongation durability and friction durability and which is suitably used for a fluid-driven actuator.

Further, by increasing the content of the silica particles (C) and the content of the silane coupling agent having a vinyl group with respect to such a silicone rubber-based curable composition, 300% modulus It is also possible to further increase the hardness while lowering the value.

Such silicone rubber can be suitably used for a part constituting a fluid-driven actuator.

A fluid-driven 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.

Fluid-driven actuators can be used for various purposes, such as artificial muscles used in daily life such as nursing care, welfare, medical care, daily life, and sports, and work in agriculture, manufacturing, and construction. It can be used as a driving device for artificial muscles that support on-site work, artificial muscles for robots, and indirect structures.

Silicone rubber can keep 300% modulus low. Therefore, the tube member made of silicone rubber tends to swell even when the energy due to the fluid pressure is small, so that a larger swelling force can be exerted and the conversion efficiency into mechanical kinetic energy can be improved.

As described above, the silicone rubber-based curable composition can be used for forming the tube member in the 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, it is possible to easily expand and expand durability against 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.

_{Let M 30 be the tensile stress at 30% elongation and M 300} be the tensile stress at 300% elongation of the cured product of the silicone rubber-based curable composition measured by the following procedure.
(Procedure for measuring tensile stress)
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 the obtained dumbbell-shaped No. 3 test piece was prepared at 25 ° C. , 30% and 300% tensile stress at stretch.

M ₃₀ and M ₃₀₀ satisfy 0.25 ≤ M ₃₀ / M ₃₀₀ ≤ 1.0.
The lower limit of M ₃₀ / M ₃₀₀ is 0.25 or more, preferably 0.30 or more, and more preferably 0.40 or more. Thereby, the elongation durability and the friction durability can be improved.
On the other hand, _{the upper limit of M 30} / M ₃₀₀ is 1.0 or less, preferably 0.9 or less, and more preferably 0.8 or less. Thereby, it is possible to balance various physical properties of the silicone rubber.

The upper limit of M ₃₀₀ is, for example, 3.0 MPa or less, preferably 2.5 MPa or less, and more preferably 2.0 MPa or less. As a result, the easy expansion and expansion / contraction durability of the silicone rubber can be improved.
On the other hand, _{the lower limit of M 300} is not particularly limited, but may be, for example, 0.1 MPa or more, 0.6 MPa or more, or 1.0 MPa or more.

The upper limit of M ₃₀ is not particularly limited, but may be, for example, 2.0 MPa or less, 1.5 MPa or less, or 1.2 MPa or less.
On the other hand, _{the lower limit of M 30} is, for example, 0.3 MPa or more, preferably 0.4 MPa or more, and more preferably 0.5 MPa or more. As a result, the deformation resistance to external stress and the frictional durability can be enhanced.

The upper limit of the durometer hardness A of the cured product of the silicone rubber-based curable composition measured by the following procedure is not particularly limited, but may be, for example, 80 or less, preferably 70 or less, and more preferably 65. It may be as follows. 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, for example, 40 or more, preferably 42 or more, and more preferably 48 or more. As a result, deformation due to external stress can be suppressed. In addition, the frictional durability and mechanical strength of silicone rubber can be enhanced.

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

The lower limit of the tensile strength of the cured product of the silicone rubber-based curable composition measured by the following procedure is, for example, 12.0 MPa or more, preferably 12.5 MPa or more, and more preferably 13.0 MPa or more. be. As a result, it is possible to realize a structure having excellent extension durability during repeated extension and deformation.
On the other hand, the upper limit of the tensile strength is not particularly limited, but may be, for example, 25 MPa or less. Thereby, various characteristics of the silicone rubber can be balanced.

(Procedure for measuring tensile strength)
A dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004) using a cured product of a silicone rubber-based curable composition, and the tensile strength of the dumbbell-shaped No. 3 test piece at 25 ° C. was determined. Measure.

The lower limit of the elongation at break of the cured product of the silicone rubber-based curable composition measured by the following procedure is, for example, 600% or more, preferably 700% or more, and more preferably 800% or more. .. Thereby, the elongation durability at the time of repeated elongation deformation can be improved.
On the other hand, the upper limit of the elongation at break is not particularly limited, but may be, for example, 2000% or less, or 1800% or less. Thereby, various characteristics of the silicone rubber can be balanced.

(Measurement conditions for elongation at break)
A dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004) using a cured product of a silicone rubber-based curable composition, and the obtained dumbbell-shaped No. 3 test piece was prepared at 25 ° C. Measure the elongation at break. The breaking elongation is calculated by [distance between marked lines (mm)] ÷ [distance between initial marked lines (20 mm)] × 100.

The upper limit of the tensile permanent elongation at 300% elongation of the cured product of the silicone rubber-based curable composition measured by the following procedure is, for example, 15.0% or less, preferably 13.0% or less, more preferably. It is 8.0% or less. As a result, it is possible to improve the use stability of the movable member to which the silicone rubber is applied even after deformation such as repeated stretching and bending.
On the other hand, the lower limit of the permanent tensile elongation at the time of 300% elongation is not particularly limited, but may be, for example, 0% or more and 0.1% or more.

(Measurement procedure for permanent tensile elongation)
Using a cured product of a silicone rubber-based curable composition, a test piece having a length of 60 mm and a width of 5 mm is punched in the thickness direction to prepare a strip-shaped test piece.
When the inter-chuck distance (initial value) is 100% (40 mm), a strip with a length of 60 mm is formed under the conditions of 25 ° C. and a speed of 500 mm / min until the inter-chuck distance becomes 400% (160 mm). The test piece is stretched by 300%, held for 1 minute, then contracted by reducing force and left for 10 minutes, and then the inter-chuck distance (length after stretching) is measured.
Using the inter-chuck distance (initial value) and the inter-chuck distance (length after stretching), the permanent tensile elongation is calculated from the following equation.
Permanent tensile elongation (%) = [(length after stretching-initial value) / initial value] x 100

The lower limit of the tear strength of the cured product of the silicone rubber-based curable composition measured by the following procedure is, for example, 25 N / mm or more, preferably 28 N / mm or more, more preferably 30 N / mm or more, still more preferable. Is 33 N / mm or more, more preferably 34 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.

(Measurement procedure of tear strength)
A crescent-shaped test piece is prepared according to JIS K6252 (2001) using a cured product of a silicone rubber-based curable composition, and the tear strength of the obtained crescent-shaped test piece is measured at 25 ° C.

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 M ₃₀ / M ₃₀₀ It is possible to control hardness, tensile stress at 30% and 300% elongation, tensile strength, breaking elongation, permanent tensile elongation, and tear strength. Among these, for example, the type and blending ratio of the resin constituting the silicone rubber, the cross-linking density of the resin, the cross-linking structure, etc. are appropriately controlled, and the blending ratio of the inorganic filler and the bond of the inorganic filler with the rubber are improved. Specifically, no second vinyl group-containing linear organopolysiloxane (A1-2) having a vinyl group content of more than 0.4 mol% is used, and only two at the ends in the molecule. Use a first vinyl group-containing linear organopolysiloxane (A1-1) having a vinyl group content of 0.4 mol% or less, and use a silane coupling agent having a vinyl group. , The content of silica particles (C) and the content of silane coupling agent can be adjusted appropriately, such as the above M ₃₀ / M ₃₀₀ , hardness, tensile stress, tensile strength, and breakage at the time of stretching at 30% and 300%. It is mentioned as a factor for setting elongation, tensile permanent elongation, and tear strength into a desired numerical range.

Although the detailed mechanism is not clear, the first vinyl group-containing direct vinyl group having a vinyl group content of 0.4 mol% or less is used without using the second vinyl group-containing linear organopolysiloxane (A1-2). By using a chain organopolysiloxane (A1-1), it is possible to increase the molecular weight between the cross-linking points in the silicone rubber as compared with the case where they are used in combination, and a silane coupling agent having a vinyl group. By using, it is possible to increase the bond between the rubber and the silica particles (C), so that while increasing the strength, the breaking strength and breaking elongation can be increased, and the 300% modulus can be suppressed to a low level, so that the elongation can be increased. It is considered that durability and friction durability can be improved.

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) may contain 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 vinyl group-containing linear organopolysiloxane (A1) contains a first vinyl group-containing linear organopolysiloxane (A1-1) having a vinyl group content of 0.4 mol% or less, and has a vinyl group content. It may be configured not to contain a second vinyl group-containing linear organopolysiloxane (A1-2) in excess of 0.4 mol%.
That is, the vinyl group-containing organopolysiloxane (A) may contain one or more of the first vinyl group-containing linear organopolysiloxane (A1-1).

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 weight average molecular weight Mw of the vinyl group-containing organopolysiloxane (A) is, for example, 5.0 × 10 ⁴ or more 1.0 × 10 ⁶ or less, preferably 1.0 × 10 ⁵ or more 9.0 × 10 ⁵ or less, and more preferably it may be 8.0 × 10 ⁵ or less 3.0 × 10 ⁵ or more.

The Mw (weight average molecular weight) / Mn (number average molecular weight) of the vinyl group-containing linear organopolysiloxane (A1) is, for example, 1.2 or more and 4.0 or less, preferably 1.4 or more and 3.5 or less. It may be preferably 1.6 or more and 2.8 or less. Mw / Mn is a degree of dispersion indicating the width of the molecular weight distribution.

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

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

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

It is preferable that the vinyl group-containing organopolysiloxane (A) contains the first vinyl group-containing linear organopolysiloxane (A1-1) represented by the following general formula (1-1).

In the above general formula (1-1), R ¹ is a vinyl group, and R ² is a methyl group or a vinyl group, preferably a methyl group. That is, the first vinyl group-containing linear organopolysiloxane (A1-1) includes one having a vinyl group amount of 0.4 mol% or less and having two vinyl groups only at the terminal in the molecule. Is preferable.

m and n are the number of repeating units constituting the first vinyl group-containing linear organopolysiloxane (A1-1) represented by the formula (1-1), and m is an integer of 0 to 2000. n is an integer from 1000 to 10000. m is preferably 0 to 1000, and n is preferably 2000 to 5000.
m and n represent the degree of polymerization calculated using the number average molecular weight Mn.
In the present specification, "~" means that an upper limit value and a lower limit value are included unless otherwise specified.

The vinyl group content of the first vinyl group-containing linear organopolysiloxane (A1-1) is 0.4 mol% or less, preferably 0.2 mol% or less, more preferably 0.1 mol% or less, and further. It is preferably 0.08 mol% or less. These may be used alone or in combination of two or more.

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 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 may contain a vinyl group-containing polyorganosiloxane (A) and silica particles (C).

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.

Silica particles (C) are, for example, the specific surface area by the BET method, for ^{example, 50m 2 / g~400m 2 / g} , preferably from 100m ² / ^{g~400m 2} / g, more preferably 200m ² / g~400m ² / G.

The average primary particle size of the silica particles (C) is, for example, preferably 1 nm to 100 nm, and more preferably about 5 nm 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 may 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.

The silane coupling agent (D) may contain 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.

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.

The silane coupling agent (D) may include a silane coupling agent having a vinyl group and a silane coupling agent having a hydrophobic group.

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, and those having a vinyl group as a functional group include methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, and methaloxy. Ekoxysilanes such as propylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane, vinylmethyldichlorosilane; divinyltetramethyldi Examples thereof include silazane, and 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 can contain platinum or the 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 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.

The upper limit of the content of silica particles (C) in the silicone rubber-based curable composition is, for example, 80 parts by weight or less and 75 parts by weight or less with respect to 100 parts by weight of the total amount of vinyl group-containing organopolysiloxane (A). , 70 parts by weight or less may be used. Thereby, the hardness and the mechanical strength such as the tensile strength can be balanced.
The lower limit of the content of the silica particles (C) is, for example, 30 parts by weight or more, preferably 35 parts by weight or more, more preferably 40 parts by weight, based on 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). It is more than a department. This makes it possible to increase the hardness.

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 lower limit of the content of the silane coupling agent having a vinyl group is, for example, 0.5 parts by weight or more, preferably 1 part by weight or more, more preferably 1 part by weight or more, based on 100 parts by weight of the vinyl group-containing organopolysiloxane (A). Is 3 parts by weight or more. This makes it possible to reduce the modulus by 300% while increasing the hardness.
On the other hand, the upper limit of the content of the silane coupling agent having a vinyl group may be, for example, 10 parts by weight or less and 8 parts by weight or less with respect to 100 parts by weight of the vinyl group-containing organopolysiloxane (A).

The blending ratio of the silane coupling agent having a hydrophobic group and the silane coupling agent having a vinyl group is, for example, 1: 0.01 or more and 1: 1.5 or less, preferably 1: 0.1 in terms of weight ratio. It is 1: 1 or less, more preferably 1: 0.2 or more and 1: 0.95 or less. By setting it within such a range, it is possible to balance various physical properties.

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 catalyst and can be appropriately set. Specifically, vinyl group-containing organopolysiloxane (A), silica particles (C), and 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). The range 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 composition is, for example, heating at 100 to 250 ° C. for 1 to 30 minutes (primary curing) and then post-baking (secondary curing) at 200 ° C. for 1 to 4 hours. ) Is done.
By going through the above steps, a silicone rubber can be obtained by using the silicone rubber-based curable 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.

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 2 (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"

(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 above synthesis step (A1-1), 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%.

(Examples 1 to 3 and Comparative Examples 1 to 3: 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 the 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.

(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.
Tensile strength, elongation at break, 30% modulus, 300% modulus, and permanent tensile elongation were measured with three samples, and the average value of the three was taken 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 at n = 5, and the average value was used as the measured value. The average value of each is shown in Table 2.

In Table 2, ">" indicates that the fracture was not reached due to the stroke limit of the tensile tester.

<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.

<Tensile strength>
Using the obtained sheet-shaped silicone rubber having a thickness of 1 mm, a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004), and the obtained dumbbell-shaped No. 3 test piece was subjected to 25 ° C. The tensile strength in was measured. The unit is MPa.

<Breaking elongation>
Using the obtained sheet-shaped silicone rubber having a thickness of 1 mm, a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004), and the obtained dumbbell-shaped No. 3 test piece was subjected to 25 ° C. The elongation at break was measured. The breaking elongation was calculated by [distance between marked lines (mm)] ÷ [distance between initial marked lines (20 mm)] × 100. The unit is%.

<30% modulus, 300% modulus>
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 at 25 ° C., a tensile speed of 500 mm / min, 30%. The tensile stress (30% modulus: M30, 300% modulus: M300) at the time of stretching in the dumbbell-shaped No. 3 test piece when stretched and stretched by 300% was measured. The unit is MPa.

<Permanent tensile elongation>
Using the obtained sheet-shaped silicone rubber having a thickness of 1 mm, a test piece having a length of 60 mm and a width of 5 mm was punched in the thickness direction to prepare a strip-shaped test piece.
When the inter-chuck distance (initial value) is 100% (40 mm), a strip with a length of 60 mm is formed under the conditions of 25 ° C. and a speed of 500 mm / min until the inter-chuck distance becomes 400% (160 mm). The test piece was stretched by 300%, held for 1 minute, then contracted by reducing force and left for 10 minutes, and then the inter-chuck distance (length after stretching) was measured.
Using the inter-chuck distance (initial value) and the inter-chuck distance (length after stretching), the permanent tensile elongation was determined from the following equation. The unit is%.
Permanent tensile elongation (%) = [(length after stretching-initial value) / initial value] x 100

<Stretching durability>
Using the obtained sheet-shaped silicone rubber having a thickness of 1 mm, a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004).
When the dumbbell-shaped No. 3 test was repeated until it broke, the stretching operation for stretching to 300% under the following conditions was repeated, and the number of times the stretching operation was repeated (the number of breaks) was calculated.
(Extension operation)
・ Initial value: 60 mm (distance between chucks), 0% elongation rate ・ At extension: 240 mm (distance between chucks), 300% elongation rate ・ Extension speed: Maximum speed 1,000 mm / min
・ Extension time: Approximately 30 seconds / cycle (1 cycle is initial value → extension → initial value)
・ Holding time: 0 seconds ・ Temperature: 25 ℃
When the calculated number of breaks was 200 or more, it was judged that the expansion and contraction durability of the silicone rubber was good and marked as ◯, and when it was less than 200, it was judged as defective and marked as x.

(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.

<Friction durability>
One end of the obtained tube member was inserted into the one-touch joint, and injection of a constant pressure was repeated.
At this time, the number of injections at the boundary between the end of the tube member and the joint was determined until the tube member was damaged by friction. The case where the number of injections is the same as or less than the number of injections in Comparative Examples 1 and 2 is indicated by x, and when the number of injections is larger than that, it is judged that the friction durability of the silicone rubber is good and is marked with ○. I wrote it.

<Easy expansion>
Using the obtained tube member, the easy expandability was evaluated as follows.
Air at a constant pressure was injected into the obtained tube member, and its expansion coefficient was evaluated. It was found that the tube members of Examples 1 to 3 had a larger coefficient of expansion in the radial direction than those of Comparative Examples 1 and 3.

The silicone rubber-based curable compositions of Examples 1 to 3 are superior in expansion and contraction durability as compared with Comparative Example 3 while increasing the hardness as compared with Comparative Examples 1 and 2, and are compared with Comparative Examples 1 and 2. The result was excellent in friction durability.
Further, it was found that the tube member formed by using the silicone rubber-based curable composition of Examples 1 to 3 was excellent in expandability.
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 (10)

A silicone rubber-based curable composition used to form a part constituting a fluid-driven actuator.
Is measured by the following procedures, when the cured product of the silicone rubber based curable composition, the tensile stress of the tensile stress at 30% elongation during M _30, 300% elongation was M _300,
M ₃₀ and M ₃₀₀ satisfy 0.25 ≤ M ₃₀ / M ₃₀₀ ≤ 1.0.
Silicone rubber-based curable composition.
(Procedure for measuring tensile stress)
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 the obtained dumbbell-shaped No. 3 test piece was obtained at 25 ° C. The tensile stress at 30% and 300% elongation is measured. The silicone rubber-based curable composition according to claim 1.
A _{silicone rubber-based curable composition in which M 300} satisfies 0.1 MPa or more and 3.0 MPa or less. The silicone rubber-based curable composition according to claim 1 or 2.
A silicone rubber-based curable composition having a durometer hardness A of 40 or more and 80 or less of the cured product of the silicone rubber-based curable 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 3.
A silicone rubber-based curable composition having a permanent tensile elongation at 300% elongation of a cured product of the silicone rubber-based curable composition measured by the following procedure, which is 15.0% or less.
(Measurement procedure for permanent tensile elongation)
Using the cured product of the silicone rubber-based curable composition, a test piece having a length of 60 mm and a width of 5 mm is punched in the thickness direction to prepare a strip-shaped test piece.
When the inter-chuck distance (initial value) is 100% (40 mm), a strip with a length of 60 mm is formed under the conditions of 25 ° C. and a speed of 500 mm / min until the inter-chuck distance becomes 400% (160 mm). The test piece is stretched by 300%, held for 1 minute, then contracted by reducing force and left for 10 minutes, and then the inter-chuck distance (length after stretching) is measured.
Using the inter-chuck distance (initial value) and the inter-chuck distance (length after stretching), the permanent tensile elongation is calculated from the following equation.
Permanent tensile elongation (%) = [(length after stretching-initial value) / initial value] x 100 The silicone rubber-based curable composition according to any one of claims 1 to 4.
A silicone rubber-based curable composition having a tensile strength of 12.0 MPa or more as a cured product of the silicone rubber-based curable composition measured by the following procedure.
(Procedure for measuring tensile strength)
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 the tensile strength of the dumbbell-shaped No. 3 test piece at 25 ° C. To measure. The silicone rubber-based curable composition according to any one of claims 1 to 5.
A silicone rubber-based curable composition in which the elongation at break of the cured product of the silicone rubber-based curable composition measured by the following procedure is 600% or more.
(Measurement conditions for elongation at break)
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 the obtained dumbbell-shaped No. 3 test piece was subjected to 25 ° C. In, the breaking elongation is measured. The breaking elongation is calculated by [distance between marked lines (mm)] ÷ [distance between initial marked lines (20 mm)] × 100. The silicone rubber-based curable composition according to any one of claims 1 to 6.
A silicone rubber-based curable composition having a tear strength of 25 N / mm or more, which is a cured product of the silicone rubber-based curable composition measured by the following procedure.
(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 silicone rubber-based curable composition according to any one of claims 1 to 7.
Vinyl group-containing polyorganosiloxane (A) and
A silicone rubber-based curable composition containing silica particles (C). The silicone rubber-based curable composition according to any one of claims 1 to 8.
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 9.

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