JP2023085568A - Elastomer and wearable device therewith - Google Patents

Abstract

An object of the present invention is to provide an elastomer excellent in conformability to irregularities.
SOLUTION: The elastomer of the present invention has a hardness of 50% when measured using a hardness meter at 25°C in accordance with JIS K6253 (1997) in a state in which the elastomer is stretched 50% according to a predetermined stretching operation. A wearable device elastomer having a durometer hardness _A50 of 20 or more and 80 or less when stretched.
[Selection figure] None

Description

TECHNICAL FIELD The present invention relates to elastomers and wearable devices using the same.

Various studies have been made on elastomers for wearable devices. As this type of technology, for example, the technology described in Patent Document 1 is known. Patent Document 1 describes that polyurethane is used for the stretchable base material of the wearable device (paragraph 0031 of Patent Document 1, FIG. 2, etc.).

JP 2018-104869 A

However, as a result of examination by the present inventors, it was found that the elastomer described in Patent Document 1 has room for improvement in terms of conformability to irregularities.

The present inventors have found that by using the physical properties in the direction perpendicular to the elongation direction when the elastomer is stretched as a guideline, it is possible to control the conformability of the elastomer to an uneven surface.
As a result of intensive studies based on such knowledge, it was found that the conformability to irregularities of the elastomer can be improved by adopting the hardness of the elastomer during elongation as an index and setting the hardness during elongation, which is an index, to a predetermined value or less. The present invention has been completed.

According to the invention,
An elastomer for wearable devices,
The durometer hardness A of the elastomer at 50% elongation when measured using a hardness tester at 25° C. in accordance with JIS K6253 (1997) while the elastomer is elongated 50% according to the elongation procedure described below. ₅₀ is 20 or more and 80 or less.
(decompression operation)
(1) A strip test piece having a predetermined thickness is produced from the elastomer.
(2) Place both ends of the strip test piece between the chucks of the stretching machine.
(3) The distance between the chucks when the strip test piece changes from a loose state to a taut state is defined as an initial value _D0 .
(4) The distance between chucks is increased by a predetermined percentage with respect to the initial value _D0 , and the strip test piece is stretched by a predetermined percentage and held for 1 minute.

Moreover, according to this invention, the wearable device provided with said elastomer is provided.

INDUSTRIAL APPLICABILITY According to the present invention, an elastomer excellent in conformability to irregularities and a wearable device using the same are provided.

FIG. 4 is a diagram for explaining a method of measuring the hardness of an elastomer when stretched; It is a top view which shows the outline|summary of a drawing machine typically. It is a figure for demonstrating the followability|trackability evaluation method of an elastomer.

An outline of the elastomer of this embodiment will be described.

The elastomer of the present embodiment is measured at 25° C. using a hardness tester in accordance with JIS K6253 (1997) in a state where the elastomer is stretched by 50% according to the following stretching operation. The elastomer for wearable devices can have a durometer hardness _A50 of 20 or more and 80 or less.

(decompression operation)
(1) A strip test piece having a predetermined thickness is produced from the elastomer.
(2) Place both ends of the strip test piece between the chucks of the drawing machine.
(3) The distance between the chucks when the strip test piece changes from a loose state to a taut state is defined as an initial value _D0 .
(4) The distance between chucks is increased by a predetermined percentage with respect to the initial value _D0 , and the strip test piece is stretched by a predetermined percentage and held for 1 minute.

2. Description of the Related Art In recent years, in wearable devices (wearable equipment), the level of wearability, such as wearing stability and wearing comfort, has become even higher.
Focusing on such wearability, the inventors thought that such wearability could be improved by enhancing the characteristics of following irregularities and steps on the surface of the body and the surface of clothing worn on the body.
As a result of investigation by the present inventors, it was found that by using the physical properties in the direction perpendicular to the elongation direction when the elastomer is stretched as a guideline, the conformability of the elastomer to the uneven surface can be controlled. As a result of intensive studies based on such knowledge, it was found that the conformability to irregularities of the elastomer can be improved by adopting the hardness of the elastomer during elongation as an index and setting the hardness during elongation, which is an index, to a predetermined value or less. It was found that the irregularity followability can be evaluated stably. In addition, the present inventors have also found a technique for measuring the hardness during elongation.

According to the elastomer of this embodiment, by setting the durometer hardness _A50 of the elastomer at the time of 50% elongation to the above upper limit or less, it is possible to realize an elastomer excellent in conformability to irregularities.

A molded article comprising the elastomer of the present embodiment can be applied to, for example, a wearable device that can be attached to the body or clothes. As wearable devices, for example, heart rate, electrocardiogram, blood pressure, medical sensors that detect biological phenomena such as body temperature, healthcare devices, bendable displays, stretchable LED arrays, stretchable solar cells, stretchable antennas, Stretchable batteries, actuators, wearable computers, and the like are included. The wearable device can be used as a member for forming elastic electrodes, elastic wiring, elastic substrates and other movable members (elastic members) that expand and contract or bend, exterior members, and the like. Among these, it is preferably used for a wearable device that is wrapped around the surface of the body or the surface of clothing.
In addition, the elastomer can be processed and molded into various shapes such as sheet-like, tubular and bag-like.

Next, the properties of the elastomer of this embodiment will be described.

The elongation durometer hardness A of an elastomer (hereinafter sometimes simply referred to as "hardness") is measured with the elastomer elongated by 50% according to the elongation operations shown in (1) to (4) above.
The size of the strip test piece of (1) is, for example, width: 5 mm x length: 100 mm, thickness: 2 mm. The thickness may be 2 mm, but may also be between 6 mm and 10 mm.
A uniaxial stretching machine for films can be used as the stretching machine (2). The stretching machine may be of manual type.
(3) The loose state of the strip test piece means a state in which almost no stress is generated from the strip test piece at both ends between the chucks. The state in which the strip test piece is in focus means a state in which a slight stress is generated from the strip test piece at both ends between the chucks.
The predetermined percentage in (4) above is either 50%, 100%, or 200%. A hardness at elongation of 50% to 200% may be subsequently measured.
The measurement point of the durometer hardness A of the strip test piece (4) is, for example, the central portion of the strip test piece or its vicinity. Using one strip test piece, the measurement may be performed with n=5, and the average value of the measurements may be used as the measured value.

In the elastomer of the present embodiment, the lower limit of the durometer hardness _A50 measured according to JIS K6253 (1997) at 25° C. when stretched by 50% is, for example, 20 or more, preferably 25. 30 or more, more preferably 30 or more. As a result, the resilience during repeated use can be improved. On the other hand, the upper limit of _A50 is 80 or less, preferably 70 or less, more preferably 65 or less. As a result, it is possible to realize an elastomer having excellent conformability to irregularities.

In the elastomer of the present embodiment, the lower limit of the durometer hardness _A100 measured according to JIS K6253 (1997) at 25° C. when stretched by 100% is, for example, 25 or more, preferably 30. 35 or more, more preferably 35 or more. Thereby, the mechanical strength can be improved. On the other hand, the upper limit of A ₁₀₀ is 85 or less, preferably 80 or less, more preferably 75 or less. As a result, it is possible to realize an elastomer having excellent conformability to irregularities. In addition, it is possible to improve stretchability and durability during elongation.

In the elastomer of the present embodiment, the lower limit of the durometer hardness _A200 measured in accordance with JIS K6253 (1997) at 25°C when stretched by 200% is, for example, 30 or more, preferably 40. or more, more preferably 50 or more. Thereby, the mechanical strength can be improved. On the other hand, the upper limit of _A200 is 90 or less, preferably 85 or less, more preferably 80 or less. As a result, it is possible to realize an elastomer having excellent conformability to irregularities. In addition, it is possible to improve stretchability and durability during elongation.

In the elastomer of this embodiment, the upper limit of the tensile stress _M100 may be, for example, 7.0 MPa or less, preferably 6.0 MPa or less, more preferably 5.0 MPa or less. Thereby, the deformability of the elastomer can be improved. On the other hand, the lower limit of the tensile stress _M100 may be 0.1 MPa or more, preferably 0.5 MPa or more, and more preferably 0.8 MPa or more. Thereby, the mechanical strength of the elastomer can be improved.

In the elastomer of this embodiment, the upper limit of the tensile stress _M200 may be, for example, 9.0 MPa or less, preferably 8.0 MPa or less, more preferably 7.5 MPa or less. Thereby, the deformability of the elastomer can be improved. On the other hand, the lower limit of the tensile stress _M200 may be 0.5 MPa or more, preferably 1.0 MPa or more, more preferably 1.5 MPa or more. Thereby, the mechanical strength of the elastomer can be improved.

In the elastomer of the present embodiment, the upper limit of ((tensile stress M ₂₀₀ −tensile stress M ₁₀₀ )/tensile stress M ₁₀₀ )×100 is, for example, 110% or less, preferably 100% or less, more preferably 90% or less. is. This makes it possible to achieve a balance of characteristics. On the other hand, the lower limit of ((tensile stress M ₂₀₀ −tensile stress M ₁₀₀ )/tensile stress M ₁₀₀ )×100 is 10% or more, preferably 15% or more, and more preferably 20% or more. Thereby, the deformability of the elastomer can be enhanced.

(Measurement conditions for tensile stress)
Tensile stress M ₁₀₀ : Tensile stress when the elastomer is stretched 100% at 25°C, measured according to JIS K6251 (2004).
Tensile stress M ₂₀₀ : Tensile stress when the elastomer is stretched 200% at 25°C, measured according to JIS K6251 (2004).

In the elastomer of the present embodiment, the upper limit of the tear strength TS0 may be, for example, 70 N/mm or less, preferably 68 N/mm or less, more preferably 65 N/mm or less, and still more preferably 60 N/mm or less. It's okay. This allows the properties of the elastomer to be balanced. On the other hand, the lower limit of the tear strength TS0 is 25 N/mm or more, preferably 30 N/mm or more, more preferably 35 N/mm or more, and still more preferably 38 N/mm or more. This can improve the scratch resistance and mechanical strength of the elastomer.

(Measurement conditions for tear strength)
Tear strength TS0: The tear strength of the elastomer measured at 25°C in accordance with JIS K6252 (2001).

In the elastomer of the present embodiment, the upper limit of elongation at break BE0 may be, for example, 1500% or less, preferably 1200% or less, more preferably 1000% or less, and even more preferably 900% or less. This makes it possible to balance the properties of the elastomer. On the other hand, the lower limit of the breaking elongation BE0 is 250% or more, preferably 300% or more, and more preferably 350% or more. This can improve the high stretchability and durability of the elastomer.

(Measurement conditions for breaking elongation)
Elongation at break BE0: The elongation at break of the elastomer measured at 25°C (room temperature) according to JIS K6251 (2004).

In the present embodiment, for example, the hardness, tensile stress, elongation at break, and tear strength can be adjusted by appropriately selecting the type and amount of each component contained in the elastomer, the preparation method of the composition for forming the elastomer, and the like. can be controlled. Among these, for example, it is necessary to appropriately control the type and compounding ratio of the resins that make up the elastomer, the crosslink density and crosslinked structure of the resin, and to improve the compounding ratio of the inorganic filler and the dispersibility of the inorganic filler. are factors for setting the hardness, tensile stress, elongation at break, and tear strength within the desired numerical ranges.

The composition of the elastomer of this embodiment will be described below.

The elastomer may contain silicone rubber from the viewpoint of being chemically stable and having excellent thermal stability.

The thermosetting elastomer can be composed of a cured product of a curable elastomer composition. Moreover, the silicone rubber can be composed of a cured product of a silicone rubber-based curable composition.

In addition, the molded article of the present embodiment may be added with optional components capable of exhibiting various functions. For example, from the viewpoint of increasing mechanical strength, the elastomer can contain an inorganic filler. As the inorganic filler, known materials can be used, and for example, silica particles can be used.

A case where a silicone rubber-based curable composition is used as the silicone rubber, which is an example of the elastomer of the present embodiment, will be described below.

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 of the present embodiment.

The vinyl group-containing organopolysiloxane (A) can 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 vinyl groups, and the vinyl groups serve as crosslinking points during curing.

The vinyl group content of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but for example, it preferably has two or more vinyl groups in the molecule and is 15 mol % or less. , 0.01 to 12 mol %. As a result, the amount of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1) is optimized, and a network can be reliably formed with each component described later. In the present embodiment, "~" means including both numerical values.

In the present specification, the vinyl group content is the mol % of the vinyl group-containing siloxane units when the total units constituting the vinyl group-containing linear organopolysiloxane (A1) are taken as 100 mol %. . However, one vinyl group is considered to be one vinyl group-containing siloxane unit.

The degree of polymerization of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is, for example, preferably in the range of about 1,000 to 10,000, more preferably in the range of about 2,000 to 5,000. The degree of polymerization can be determined, for example, as a polystyrene-equivalent number-average polymerization degree (or number-average molecular weight) in GPC (gel permeation chromatography) using chloroform as a developing solvent.

Furthermore, 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.

As the vinyl group-containing linear organopolysiloxane (A1), the heat resistance, flame retardancy, chemical stability, etc. of the resulting silicone rubber can be improved by using those having the degree of polymerization and specific gravity within the ranges described above. can be improved.

As the vinyl group-containing linear organopolysiloxane (A1), those having a structure represented by the following formula (1) are particularly preferable.

In formula (1), R ¹ is a substituted or unsubstituted alkyl group, alkenyl group, aryl group, or a hydrocarbon group of a combination thereof having 1 to 10 carbon atoms. The alkyl group having 1 to 10 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. The alkenyl group having 1 to 10 carbon atoms includes, for example, vinyl group, allyl group, butenyl group, etc. Among them, vinyl group is preferred. The aryl group having 1 to 10 carbon atoms includes, for example, a phenyl group.

R ² is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, or a hydrocarbon group combining these. The alkyl group having 1 to 10 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. Examples of alkenyl groups having 1 to 10 carbon atoms include vinyl groups, allyl groups and butenyl groups. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

R ³ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group combining these. The alkyl group having 1 to 8 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group.

Furthermore, examples of substituents for R ¹ and R ² in formula (1) include methyl group and vinyl group, and examples of substituents for R ³ include methyl group.

In formula (1), a plurality of R ¹ are independent of each other and may be different from each other or may be the same. Furthermore, the same applies to R ² and R ³ .

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

Further, specific structures of the vinyl group-containing linear organopolysiloxane (A1) represented by formula (1) include, for example, those represented by the following formula (1-1).

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

Furthermore, as the vinyl group-containing linear organopolysiloxane (A1), a first vinyl group-containing vinyl group having a vinyl group content of 2 or more vinyl groups in the molecule and not more than 0.4 mol% It contains a linear organopolysiloxane (A1-1) and a second vinyl group-containing linear organopolysiloxane (A1-2) having a vinyl group content of 0.5 to 15 mol%. It is preferable to have As crude rubber, which is a raw material of silicone rubber, a first vinyl group-containing linear organopolysiloxane (A1-1) having a general vinyl group content and a second vinyl group-containing linear organopolysiloxane having a high vinyl group content were used. By combining with the chain organopolysiloxane (A1-2), the vinyl groups can be unevenly distributed, and the crosslink density can be more effectively formed in the crosslink network of the silicone rubber. As a result, the tear strength of silicone rubber can be increased more effectively.

Specifically, as the vinyl group-containing linear organopolysiloxane (A1), for example, a unit in which R ¹ is a vinyl group and/or a unit in which R ² is a vinyl group in the above formula (1-1) , 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 units in which ² is a vinyl group.

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

Furthermore, when combining the first vinyl group-containing linear organopolysiloxane (A1-1) and the second vinyl group-containing linear organopolysiloxane (A1-2), (A1-1) 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: 10 is more preferred.

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

The vinyl group-containing organopolysiloxane (A) may also contain a vinyl group-containing branched organopolysiloxane (A2) having a branched structure.

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

The linear organohydrogenpolysiloxane (B1) has a linear structure and a structure (≡Si—H) in which hydrogen is directly bonded to Si, and is the vinyl group-containing organopolysiloxane (A). It is a polymer that undergoes a hydrosilylation reaction with vinyl groups other than vinyl groups contained in other components of the silicone rubber-based curable composition, thereby cross-linking these components.

The molecular weight of the linear organohydrogenpolysiloxane (B1) is not particularly limited.

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.

Also, the straight-chain organohydrogenpolysiloxane (B1) generally preferably does not have a vinyl group. Thereby, it is possible to accurately prevent the progress of the cross-linking reaction 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 formula (2), R ⁴ is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, a hydrocarbon group combining these groups, or a hydride group. The alkyl group having 1 to 10 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferable. Examples of alkenyl groups having 1 to 10 carbon atoms include vinyl groups, allyl groups and butenyl groups. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

R ⁵ is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, a hydrocarbon group combining these, or a hydride group. Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group and propyl group, with methyl group being preferred. Examples of alkenyl groups having 1 to 10 carbon atoms include vinyl groups, allyl groups and butenyl groups. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

In formula (2), a plurality of R ⁴ are independent of each other and may be different from each other or may be the same. The same is true for ^R5 . However, at least two or more of the plurality of R ⁴ and R ⁵ are hydride groups.

R ⁶ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group combining these. The alkyl group having 1 to 8 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. 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 and may be different from each other or may be the same.

Examples of substituents for R ⁴ , R ⁵ and R ⁶ in formula (2) include methyl group and vinyl group, with methyl group being preferred from the viewpoint of preventing intramolecular cross-linking reaction.

Furthermore, m and n are the numbers of repeating units constituting the linear organohydrogenpolysiloxane (B1) represented by formula (2), m is an integer of 2 to 150, and n is an integer of 2 to 150. is an integer. Preferably, m is an integer from 2-100 and n is an integer from 2-100.

In addition, linear organohydrogenpolysiloxane (B1) may be used individually by 1 type, and may be used in combination of 2 or more type.

Since the branched organohydrogenpolysiloxane (B2) has a branched structure, it is a component that forms regions with a high crosslink density and greatly contributes to the formation of a loose and dense crosslink density structure 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 undergoes a hydrosilylation reaction with the vinyl groups of the components blended in the rubber-based curable composition to crosslink these components.

Further, the branched organohydrogenpolysiloxane (B2) has a specific gravity in the range of 0.9 to 0.95.

Furthermore, it is generally preferred that the branched organohydrogenpolysiloxane (B2) does not have a vinyl group. Thereby, it is possible to accurately prevent the progress of the cross-linking reaction in the molecule of the branched organohydrogenpolysiloxane (B2).

As the branched organohydrogenpolysiloxane (B2), those represented by the following average compositional formula (c) are preferred.

Average composition formula (c)
(H _a (R ⁷ ) _3-a SiO _1/2 ) _m (SiO _4/2 ) _n
(In formula (c), R ⁷ is a monovalent organic group, a is an integer ranging from 1 to 3, m is the number of H _a (R ⁷ ) _3-a SiO _1/2 units, n is SiO _4/ 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 combining these. The alkyl group having 1 to 10 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

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

In formula (c), m is the number of H _a (R ⁷ ) _3-a SiO _1/2 units, and 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. The number of bound alkyl groups R (R/Si) is 1.8 to 2.1 for the linear organohydrogenpolysiloxane (B1) and 0.8 to 1 for the branched organohydrogenpolysiloxane (B2). .7 range.

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

Specific examples of the branched organohydrogenpolysiloxane (B2) include those having a structure represented by the following formula (3).

In formula (3), R ⁷ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, a hydrocarbon group combining these, or a hydrogen atom. The alkyl group having 1 to 8 carbon atoms includes, for example, methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. Examples of the substituent of ^R7 include a methyl group and the like.

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

In formula (3), "--O--Si.ident." represents that Si has a branched structure extending three-dimensionally.

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

Moreover, 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, linear organohydrogenpolysiloxane (B1) and branched organohydrogenpolysiloxane are The total amount of hydride groups in the siloxane (B2) is preferably from 0.5 to 5 mol, more preferably from 1 to 3.5 mol. As a result, a crosslinked network is reliably formed between the linear organohydrogenpolysiloxane (B1), the branched organohydrogenpolysiloxane (B2), and the vinyl group-containing linear organopolysiloxane (A1). can be made

<<Silica particles (C)>>
The silicone rubber-based curable composition of the present embodiment can contain silica particles (C).

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

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

By using silica particles (C) having a specific surface area and an average particle size within the above ranges, the hardness and mechanical strength of the silicone rubber formed can be improved, particularly the tensile strength can be improved.

<<Silane coupling agent (D)>>
The silicone rubber-based curable composition of the present embodiment can contain a silane coupling agent (D).
Silane coupling agent (D) can have a hydrolyzable group. The hydrolyzable group is hydrolyzed with water to form a hydroxyl group, and the hydroxyl group undergoes a dehydration condensation reaction with the hydroxyl group on the surface of the silica particle (C), thereby modifying the surface of the silica particle (C).

Moreover, this silane coupling agent (D) can contain a silane coupling agent having a hydrophobic group. As a result, the hydrophobic group is imparted to the surface of the silica particles (C), so that the cohesive force of the silica particles (C) in the silicone rubber-based curable composition and further in the silicone rubber is reduced (hydrogen aggregation due to bonding is reduced), and as a result, it is presumed that the dispersibility of the silica particles in the silicone rubber-based curable composition is improved. This increases the interface between the silica particles and the rubber matrix, increasing the reinforcing effect of the silica particles. Furthermore, it is presumed that the slipperiness of the silica particles in the matrix is improved when the rubber matrix is deformed. The improved dispersibility and slipperiness of the silica particles (C) improve the mechanical strength (for example, tensile strength and tear strength) of the silicone rubber due to the silica particles (C).

Furthermore, the silane coupling agent (D) can contain a silane coupling agent having a vinyl group. As a result, vinyl groups are introduced onto the surfaces of the silica particles (C). Therefore, during curing of the silicone rubber-based curable composition, that is, a hydrosilylation reaction occurs between the vinyl group of the vinyl group-containing organopolysiloxane (A) and the hydride group of the organohydrogenpolysiloxane (B). , When a network (crosslinked structure) is formed by these, the vinyl groups possessed by the silica particles (C) also participate in the hydrosilylation reaction with the hydride groups possessed by the organohydrogenpolysiloxane (B). Silica particles (C) also come to be taken in. 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).

_Yn -Si-(X) _4-n (4)
In the above formula (4), n represents an integer of 1-3. Y represents a 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 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 having a combination thereof, and examples thereof include a methyl group, an ethyl group, a propyl group, a phenyl group, and the like. Methyl groups are preferred.

Moreover, the hydrophilic group includes, for example, a hydroxyl group, a sulfonic acid group, a carboxyl group, a carbonyl group, etc. 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, the hydrolyzable group includes an alkoxy group such as a methoxy group and an ethoxy group, a chloro group, a silazane group, and the like. Among them, a silazane group is preferable because of its high reactivity with the silica particles (C). A compound having a silazane group as a hydrolyzable group has two structures of (Y _n —Si—) in the above formula (4) due to its structural characteristics.

Specific examples of the silane coupling agent (D) represented by the above formula (4) include, for example, those having a hydrophobic group as a functional group, such as methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane, Alkoxysilanes such as ethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane; methyltrichlorosilane; chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane; hexamethyldisilazane; alkoxysilanes such as propylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane, vinylmethyldichlorosilane; Among them, hexamethyldisilazane is particularly preferable as one having a hydrophobic group, and divinyltetramethyldisilazane as one having a vinyl group, in view of the above description.

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

As the platinum or platinum compound (E), a known one can be used, for example, platinum black, platinum supported on silica or carbon black, chloroplatinic acid or an alcohol solution of chloroplatinic acid, A complex salt of platinic acid and olefin, a complex salt of chloroplatinic acid and vinyl siloxane, and the like are included.

In addition, platinum or a platinum compound (E) may be used individually by 1 type, and may be used in combination of 2 or more type.

The silicone rubber-based curable composition of this embodiment can contain an organic peroxide (H). Organic peroxide (H) is a component that acts as a catalyst. The amount of organic peroxide (H) added is a catalytic amount. The organic peroxide (H) is used in place of the organohydrogenpolysiloxane (B) and platinum or a platinum compound (E), or in combination with the organohydrogenpolysiloxane (B) and platinum or a platinum compound (E) and an organic peroxide. (H) can be used in combination.

Examples of organic peroxides (H) include ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, peroxyketals, alkyl peresters, peroxyesters and peroxydioxides. carbonates, and specific examples include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, o-methylbenzoyl peroxide, dicumyl peroxide, 2,5-dimethyl- bis(2,5-t-butylperoxy)hexane, di-t-butylperoxide, t-butylperbenzoate, 1,6-hexanediol-bis-t-butylperoxycarbonate and the like.

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

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

In addition, although the content ratio of each component in the silicone rubber-based curable composition is not particularly limited, it 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, with respect to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). or less, and more preferably 35 parts by weight or less. This makes it possible to balance mechanical strength such as hardness and tensile strength. Moreover, the lower limit of the content of the silica particles (C) is not particularly limited to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A), but may be, for example, 20 parts by weight or more.

The silane coupling agent (D) preferably contains, for example, 5 parts by weight or more and 100 parts by weight or less of the silane coupling agent (D) with respect to 100 parts by weight of the vinyl group-containing organopolysiloxane (A). , more preferably 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 reliably improved.

The content of the organohydrogenpolysiloxane (B) is specifically based on 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), for example , preferably 0.5 to 20 parts by weight, more preferably 0.8 to 15 parts by weight. When the content of (B) is within the above range, a more effective curing reaction may be possible.

The content of platinum or platinum compound (E) means the amount of catalyst and can be set as appropriate. Specifically, vinyl group-containing organopolysiloxane (A), silica particles (C), 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, per 100 parts by weight of D). By setting the content of platinum or platinum compound (E) to the above lower limit or more, the resulting silicone rubber composition can be sufficiently cured. By setting the content of platinum or platinum compound (E) to the above upper limit or less, the curing speed of the obtained silicone rubber composition can be improved.

The content of the organic peroxide (H) means the amount of catalyst and can be set as appropriate. It is, for example, 0.001 parts by weight or more, preferably 0.005 parts by weight or more, and more preferably 0.01 parts by weight or more with respect to 100 parts by weight of the total amount of D). Thereby, the minimum strength as a cured product can be ensured. Further, the upper limit of the content of the organic peroxide (H) is, relative to the total amount of 100 parts by weight of the vinyl group-containing organopolysiloxane (A), the silica particles (C), and the silane coupling agent (D), For example, it is 10 parts by weight or less, preferably 5 parts by weight or less, more preferably 3 parts by weight or less. Thereby, the influence by a by-product can be suppressed.

Furthermore, when water (F) is contained, its content can be appropriately set, specifically, for 100 parts by weight of the silane coupling agent (D), for example, 10 to 100 parts by weight and more preferably 30 to 70 parts by weight. This allows the reaction between the silane coupling agent (D) and the silica particles (C) to proceed more reliably.

<Method for producing silicone rubber>
Next, a method for producing the silicone rubber of this embodiment will be described.
As a method for producing the silicone rubber of the present embodiment, the silicone rubber can be obtained by preparing a silicone rubber-based curable composition and curing the silicone rubber-based curable composition.
Details will be described below.

First, each component of the silicone rubber-based curable composition is uniformly mixed using any kneading device to prepare the 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 predetermined amounts, and then kneaded with an arbitrary kneading device, A kneaded material containing these components (A), (C) and (D) is obtained.

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

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

Further, the kneading of the components (A), (C) and (D) is preferably carried out through a first step of heating at a first temperature and a second step of heating at a second temperature. As a result, 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) By-products generated in the reaction can be reliably removed from the kneaded material. After that, if necessary, the component (A) may be added to the obtained kneaded product and further kneaded. This makes it possible to improve the familiarity of the components of the kneaded product.

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

Moreover, 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.

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

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

[2] Next, the organohydrogenpolysiloxane (B) and the platinum or platinum compound (E) are weighed in predetermined amounts, and then the kneaded product prepared in the above step [1] using any kneading device. Then, the respective components (B) and (E) are 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 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 material with platinum or the platinum compound (E), and then knead the respective kneaded materials. This ensures that each component (A) to (E) is contained in the silicone rubber-based curable composition without allowing the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) to proceed. can be distributed in

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

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

In the steps [1] and [2], the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) proceeds more accurately by setting the temperature within the above range. can be prevented or suppressed; In addition, by setting the kneading time within the above range in steps [1] and [2], each component (A) to (E) can be more reliably dispersed in the silicone rubber-based curable composition. can be done.

The kneading device used in steps [1] and [2] is not particularly limited, but for example, a kneader, two rolls, a Banbury mixer (continuous kneader), a pressure kneader, etc. can be used.

In 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) can be more accurately prevented or suppressed. be able to.

Further, in this step [2], in place of the organohydrogenpolysiloxane (B) and platinum or the platinum compound (E), or in combination with the organohydrogenpolysiloxane (B) and platinum or the platinum compound (E) , an organic peroxide (H) may be added. Preferred conditions such as temperature and time for kneading the organic peroxide (H) and the equipment to be used are the conditions for kneading the organohydrogenpolysiloxane (B) and the platinum or platinum compound (E). is similar 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 includes, for example, heating at 100 to 250° C. for 1 to 30 minutes (primary curing), followed by post-baking at 200° C. for 1 to 4 hours (secondary curing). curing).
The silicone rubber of the present embodiment is obtained through the steps described above.

As a result of examination by the present inventor, the following findings were obtained. It was found that if the amount of filler in silicone rubber is reduced, the hardness and tensile stress can be reduced, but on the other hand, the tear strength is lowered and the durability of the silicone rubber is lowered.

Therefore, as a result of intensive studies, by appropriately selecting a resin composition such as a vinyl group-containing organopolysiloxane (A), it is possible to control the uneven distribution of cross-linking density and cross-linking structure, and to achieve low stress and low hardness in a wide strain range. It was found that the tear strength of the silicone rubber can be increased while realizing this. Moreover, it turned out that the tensile strength of silicone rubber can also be improved. Although the detailed mechanism is not clear, the combination of high-vinyl group-containing organopolysiloxane and low-vinyl group-containing organopolysiloxane makes it possible to control uneven distribution of the crosslinked structure, thereby increasing the tear strength of silicone rubber while reducing hardness. It is considered possible. Thus, by increasing the tear strength while maintaining other physical properties, the breaking energy of the silicone rubber can be increased.

In the present embodiment, for example, by appropriately selecting the type and amount of each component contained in the silicone rubber-based curable composition, the preparation method of the silicone rubber-based curable composition, the production method of the silicone rubber, etc., It is possible to control the tensile stress, elongation at break, tensile strength, tear strength and hardness. Among these, for example, a combination of a low vinyl group-containing linear organopolysiloxane (A1-1) and a high vinyl group-containing linear organopolysiloxane (A1-2), a vinyl group having a terminal vinyl group By using the group-containing organopolysiloxane (A), the crosslink density of the resin and the uneven distribution of the crosslinked structure are controlled, and the addition timing and ratio of the vinyl group-containing organopolysiloxane (A), silica particles (C) The reaction between the silane coupling agent (D) and the silica particles (C), such as the compounding ratio of the silica particles (C) with the silane coupling agent (D), and the addition of water, are more reliable. and the like are factors for making the above-mentioned tensile stress, elongation at break, tensile strength, and tear strength within desired numerical ranges.

In the present embodiment, when measuring the tensile stress, elongation at break, tensile strength, and tear strength of the curable silicone rubber composition, a cured product of the curable silicone rubber composition is used as the object to be heated and measured. be able to. As this cured product, for example, a silicone rubber-based curable composition is pressed at 160° C. and 10 MPa for 20 minutes to form a sheet having a thickness of 1 mm, and is subjected to primary curing, followed by 4 hours at 200° C. A sheet-shaped silicone rubber (cured product of a silicone rubber-based curable composition) obtained by heating and secondary curing may also be used.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can also be adopted.

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

Raw material components used in Examples and Comparative Examples shown in Table 1 are shown below.
(Vinyl group-containing organopolysiloxane (A))
Low-vinyl group-containing linear organopolysiloxane (A1-1): a vinyl group-containing dimethylpolysiloxane synthesized according to Synthesis Scheme 1 (structure represented by formula (1-1) where only R ¹ (terminal) is a vinyl group structure that is
High vinyl group-containing linear organopolysiloxane (A1-2): Vinyl group-containing dimethylpolysiloxane synthesized according to Synthesis Scheme 2 (structure represented by formula (1-1) with R ¹ and R ² being vinyl groups some structure)

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

(Silica particles (C))
・Silica particles (C): Silica fine particles (particle diameter 7 nm, specific surface area 300 m ² /g), manufactured by Nippon Aerosil Co., Ltd., "AEROSIL 300"

(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))
Momentive: "TC-25A"

(Synthesis of vinyl group-containing organopolysiloxane (A))
[Synthesis Scheme 1: Synthesis of Low Vinyl Group-Containing Linear Organopolysiloxane (A1-1)]
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 siliconate were placed in a 300 mL separable flask having a cooling tube and a stirring blade, which was replaced with Ar gas, and the temperature was raised to 120° C. for 30 minutes. Stirred. At this time, an increase in viscosity was confirmed.
After that, the temperature was raised to 155° C. and stirring was continued for 3 hours. 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.
Furthermore, after 4 hours, it was diluted with 250 mL of toluene and then washed with water three times. The washed organic layer was washed several times with 1.5 L of methanol for reprecipitation purification to separate the oligomer and polymer. The obtained polymer was dried overnight under reduced pressure at 60° C. to obtain a low-vinyl group-containing linear organopolysiloxane (A1-1) (Mn=2,2×10 ⁵ , Mw=4,8×10 ⁵ ). Also, the vinyl group content calculated by H-NMR spectrum measurement was 0.04 mol %.

[Synthesis Scheme 2: Synthesis of High Vinyl Group-Containing Linear Organopolysiloxane (A1-2)]
In the above synthesis step (A1-1), 0.7 g (252 mmol) of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane was added to 74.7 g (252 mmol) of octamethylcyclotetrasiloxane. Except for using 86 g (2.5 mmol), the same synthesis step as in (A1-1) was performed to obtain a high-vinyl group-containing linear organopolysiloxane (A1- 2) was synthesized. (Mn=2,3×10 ⁵ , Mw=5,0×10 ⁵ ). Also, the vinyl group content calculated by H-NMR spectrum measurement was 0.93 mol %.

(Example 1: Preparation of silicone rubber-based curable composition)
In Example 1, the silicone rubber-based curable composition was prepared as follows. First, a mixture of a vinyl group-containing organopolysiloxane (A), a silane coupling agent (D) and water (F) is kneaded in advance in proportions shown in Table 1 below, and then silica particles (C) are added to the mixture. In addition, the mixture was further kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after the addition of the silica particles (C) includes a first step of kneading for 1 hour under a nitrogen atmosphere at 60 to 90° C. for the coupling reaction, and removal of the by-product (ammonia). For this purpose, a second step of kneading for 2 hours under conditions of 160 to 180° C. under a reduced pressure atmosphere was performed, followed by cooling and kneading for 20 minutes.
Subsequently, 1.81 parts by weight of organohydrogenpolysiloxane (TC-25D) and 0.5 parts by weight of platinum or a platinum compound (TC-25A) were added to 100 parts by weight of the resulting kneaded product (silicone rubber compound). and kneaded with a roll to obtain a silicone rubber-based curable composition of Example 1.

(Example 2: Preparation of silicone rubber-based curable composition)
In Example 2, a silicone rubber-based curable composition was prepared in the same manner as in Example 1. First, a mixture of vinyl group-containing organopolysiloxane (A), silane coupling agent (D) and water (F) is kneaded in advance at the ratio shown in Table 1, and then silica particles (C) are added to the mixture. The mixture was further kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after adding the silica particles (C) was performed in the same manner as in Example 1.
Subsequently, 3.77 parts by weight of organohydrogenpolysiloxane (TC-25D) and 0.5 parts by weight of platinum or a platinum compound (TC-25A) were added to 100 parts by weight of the resulting kneaded product (silicone rubber compound). and kneaded with a roll to obtain a silicone rubber-based curable composition of Example 2.

(Example 3: Preparation of silicone rubber-based curable composition)
In Example 3, a silicone rubber-based curable composition was prepared in the same manner as in Example 1. First, a mixture of vinyl group-containing organopolysiloxane (A), silane coupling agent (D) and water (F) is kneaded in advance at the ratio shown in Table 1, and then silica particles (C) are added to the mixture. The mixture was further kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after adding the silica particles (C) was performed in the same manner as in Example 1.
Subsequently, 4.53 parts by weight of organohydrogenpolysiloxane (TC-25D) and 0.5 parts by weight of platinum or a platinum compound (TC-25A) were added to 100 parts by weight of the resulting kneaded product (silicone rubber compound). and kneaded with a roll to obtain a silicone rubber-based curable composition of Example 3.

(Example 4: Preparation of silicone rubber-based curable composition)
In Example 4, a silicone rubber-based curable composition was prepared in the same manner as in Example 1. First, a mixture of vinyl group-containing organopolysiloxane (A), silane coupling agent (D) and water (F) is kneaded in advance at the ratio shown in Table 1, and then silica particles (C) are added to the mixture. The mixture was further kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after adding the silica particles (C) was performed in the same manner as in Example 1.
Subsequently, 2.26 parts by weight of organohydrogenpolysiloxane (TC-25D) and 0.5 parts by weight of platinum or a platinum compound (TC-25A) were added to 100 parts by weight of the resulting kneaded product (silicone rubber compound). and kneaded with a roll to obtain a silicone rubber-based curable composition of Example 4.

(Example 5: Preparation of silicone rubber-based curable composition)
In Example 5, a silicone rubber-based curable composition was prepared in the same manner as in Example 1. First, a mixture of vinyl group-containing organopolysiloxane (A), silane coupling agent (D) and water (F) is kneaded in advance at the ratio shown in Table 1, and then silica particles (C) are added to the mixture. The mixture was further kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after adding the silica particles (C) was performed in the same manner as in Example 1.
Subsequently, 4.53 parts by weight of organohydrogenpolysiloxane (TC-25D) and 0.5 parts by weight of platinum or a platinum compound (TC-25A) were added to 100 parts by weight of the resulting kneaded product (silicone rubber compound). and kneaded with a roll to obtain a silicone rubber-based curable composition of Example 5.

(Production of silicone rubber)
In Examples 1 to 5, 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 2 mm, and was subjected to primary curing. Subsequently, it was heated at 200° C. for 4 hours for secondary curing. As described above, a sheet-like silicone rubber (cured product of a silicone rubber-based curable composition) was obtained as a sheet-like elastomer.

[Comparative Example 1]
A chloroprene rubber sheet (thickness: 2 mm, width: 500 mm x length: 500 mm, Gomutsu product code: 10037) purchased from Fuso Rubber Co., Ltd. was used as a sheet-like elastomer.
[Comparative Example 2]
A fluororubber sheet (thickness: 2 mm, width: 300 mm x length: 300 mm, Gomutsu product code: 10001) purchased from Fuso Rubber Co., Ltd. was used as a sheet-like elastomer.

The sheet-like elastomers obtained in Examples and Comparative Examples were evaluated based on the following evaluation items.

(hardness)
The shape of the resulting 2 mm thick elastomer sheet was processed to prepare a strip test piece 10 (FIG. 1(a)) having a width of 5 mm, a length of 100 mm, and a thickness of 2 mm.
The obtained strip test piece 10 was placed on a slide glass so that the top view shape was rectangular. With both ends of the strip test piece 10 loosened without being pulled, the width of the strip test piece 10 at 25 ° C. is measured using a hardness tester 20 (manufactured by Techclock, product name: GS-610, an automatic constant pressure loader for durometers). The unstretched hardness _A0 at the central portion 30 of the direction was measured.
The hardness was measured in a state in which the base of the hardness tester 20 with an indentation needle was pressed parallel to the rectangular surface of the strip test piece 10 .

Subsequently, a manual stretching machine 100 (uniaxial stretching machine for film) shown in FIG. 2 was prepared.
The manual stretching machine 100 has a chuck 102 as one fixed end and a chuck 104 movable in the axial direction of a shaft 110 . Both ends of the plate-shaped film can be fixed to the chucks 102 and 104 . The chuck 104 moves relative to the chuck 102 in the axial direction while the film is fixed.
Between one fixed end (chuck 102) and the other fixed end 112, a shaft 110 fixed to the fixed end 112, and guides 106 and 108 are arranged parallel to the shaft 110 and on both sides thereof. Therefore, the chuck 104 moves along the two guides, and can move more accurately in the axial direction.
After moving the chuck 104 to a predetermined position in the axial direction and setting the chuck-to-chuck distance to a predetermined value, the chuck 104 can be fixed to the guides 106 and 108 by the fixing portions 114 and 116 .

Subsequently, both ends of the strip test piece 10 were placed on the chucks 102 and 104 of the manual stretching machine 100, respectively, and the strip test piece 10 was stretched. The chuck-to-chuck distance when the strip test piece 10 changed from a loose state to a taut state was set to an initial value D ₀ (40 mm) (FIG. 1(b)).

Subsequently, using the manual stretching machine 100, the strip test piece 10 was stretched until the distance D _x between chucks was 60 mm, held for 1 minute, and then stretched at 25 ° C. in accordance with JIS K6253 (1997). At the central portion 30 of the strip test piece 10, the hardness _A50 at 50% elongation was measured with a hardness meter 20 (Fig. 1(c)).
Subsequently, using the manual stretching machine 100, the strip test piece 10 was stretched until the distance D _x between the chucks was 80 mm, held for 1 minute, and then stretched at 25 ° C. in accordance with JIS K6253 (1997). The hardness A100 at 100% elongation was measured with a hardness meter ₂₀ at the central portion 30 of the strip test piece 10 .
Subsequently, using the manual stretching machine 100, the strip test piece 10 was stretched until the distance D _x between the chucks was 120 mm, held for 1 minute, and then stretched at 25 ° C. in accordance with JIS K6253 (1997). The hardness _A200 at 200% elongation was measured with a hardness meter 20 at the central portion 30 of the strip test piece 10 .

Hardnesses A ₀ , A ₅₀ , A ₁₀₀ , and A ₂₀₀ were measured using one sample (strip test piece) with n=5 for each sample, and the average value of the measurements was taken as the measured value. Each average value is shown in Table 2.

"-" in Table 3 means that measurement could not be performed due to breakage.

Tensile stress and elongation at break were measured for three samples, and the average value of the three values was used as the measured value. Five samples were measured for tear strength, and the average value of the five samples was used as the measured value. Each average value is shown in Table 3.

<Tear strength>
A crescent-shaped test piece was prepared according to JIS K6252 (2001) at 25° C. using the resulting 2 mm-thick sheet-like elastomer, and the tear strength of the obtained crescent-shaped test piece was measured. The unit is N/mm.

<Tensile stress>
Using the obtained sheet-like elastomer with a thickness of 2 mm, a dumbbell-shaped No. 3 test piece was prepared in accordance with JIS K6251 (2004) at 25 ° C., and the tensile speed was 500 mm / min. The tensile stress M ₁₀₀ (100% modulus) at 100% elongation and the tensile stress M ₂₀₀ (200% modulus) at 200% elongation of the dumbbell-shaped No. 3 test piece were measured. The unit is MPa.

<Breaking elongation>
Using the obtained sheet-like elastomer with a thickness of 2 mm, a dumbbell-shaped No. 3 test piece was prepared at 25 ° C. in accordance with JIS K6251 (2004), and the obtained dumbbell-shaped No. 3 test piece was Elongation at break was measured. The elongation at break was calculated by [moving distance between chucks (mm)]÷[initial distance between chucks (60 mm)]×100. The unit is %.

<Followability>
First, a sheet-like test piece 50, a recessed substrate 60, and a Kiriyama funnel 70 described below were prepared.
(Sheet-shaped test piece 50)
Using the sheet-like elastomer of each example and each comparative example, a sheet-like test piece 50 having a size of 15 cm square and a thickness of 0.5 mm was prepared. The top view shape of the sheet-shaped test piece 50 was a square.
(Concave substrate 60)
A recessed substrate 60 was prepared in which a recessed groove 62 was formed in the depth direction from the surface of the substrate. The depth D of the groove 62 was set to 2 mm (FIG. 3(a)), and the diameter (width W) of the groove 62 was set to 20 mm (FIG. 3(b)).
As shown in FIG. 3B, the concave substrate 60 has a square shape when viewed from above, and the concave groove 62 has a circular shape when viewed from above.
FIG. 3(b) is a view taken along line AA in FIG. 3(a) (a cross-sectional view in a direction perpendicular to the top view direction).
(Kiriyama Roth 70)
As the Kiriyama funnel 70, model: S-60 was used. In the Kiriyama funnel 70, the width of the inside of the mouth end was 85 mm, and the height H of the inside of the mouth was 53 mm.

Subsequently, the sheet-shaped test piece 50 was placed on the prepared concave substrate 60 so as to cover the concave groove 62 . Subsequently, the mouth end of the Kiriyama funnel 70 was pressed around the sheet-shaped test piece 50 (Fig. 3(a)).

Subsequently, the pressure inside the mouth of the Kiriyama funnel 70 was reduced to 300 mmHg (FIGS. 3(c) to 3(e)). At such reduced pressure, the followability of the sheet-shaped test piece 50 to the inner wall of the funnel mouth was evaluated based on the following evaluation criteria. Table 4 shows the evaluation results.

(Evaluation criteria)
Figure 3(c): The sheet-shaped test piece 50 expands during decompression and reaches the entire surface of the inner wall of the mouth. ◯, and FIG. 3(e): X, which did not reach the upper surface of the inner wall of the mouth.

It was found that the elastomers (silicone rubber) of Examples 1-5 are superior to those of Comparative Examples 1-2 in conformability to irregularities. Such elastomers of Examples 1 to 5 are expected to be suitably used for wearable devices that require followability, especially stretchable members of wearable devices.

10 strip test piece 20 hardness tester 30 central portion 50 sheet-like test piece 60 recessed substrate 62 recessed groove 70 Kiriyama funnel 100 manual stretching machine 102 chuck 104 chuck 106 guide 108 guide 110 shaft 112 fixed end 114 fixed portion 116 fixed portion

Claims (11)

An elastomer for wearable devices,
The durometer hardness A of the elastomer at 50% elongation when measured using a hardness tester at 25° C. in accordance with JIS K6253 (1997) while the elastomer is elongated 50% according to the elongation procedure described below. ₅₀ is 20 or more and 80 or less;
(decompression operation)
(1) A strip test piece having a predetermined thickness is produced from the elastomer.
(2) Place both ends of the strip test piece between the chucks of the drawing machine.
(3) The distance between the chucks when the strip test piece changes from a loose state to a taut state is defined as an initial value _D0 .
(4) The distance between chucks is increased by a predetermined percentage with respect to the initial value _D0 , and the strip test piece is stretched by a predetermined percentage and held for 1 minute. The elastomer of claim 1, comprising:
Durometer hardness A of the elastomer at 100% elongation when measured using a hardness tester at 25° C. in accordance with JIS K6253 (1997) while the elastomer is elongated 100% according to the elongation procedure described above. an elastomer wherein ₁₀₀ is 25 or more and 85 or less; 3. An elastomer according to claim 1 or 2,
The durometer hardness A of the elastomer at 200% elongation when measured using a hardness tester at 25° C. in accordance with JIS K6253 (1997) while the elastomer is elongated 200% according to the elongation procedure described above. ₂₀₀ is 30 or more and 90 or less. The elastomer according to any one of claims 1 to 3,
An elastomer having a tensile stress _M100 of 0.1 MPa or more and 7.0 MPa or less when 100% elongation is measured at 25°C in accordance with JIS K6251 (2004). The elastomer according to any one of claims 1 to 3,
An elastomer having a tensile stress _M200 of 0.5 MPa or more and 9.0 MPa or less when 200% elongation is measured at 25°C in accordance with JIS K6251 (2004). The elastomer according to any one of claims 1 to 5,
An elastomer in which ((M ₂₀₀ −M ₁₀₀ )/M ₁₀₀ )×100 is 10% or more and 110% or less.
Above M ₁₀₀ : Tensile stress M ₁₀₀ of the elastomer at 100% elongation when measured according to JIS K6251 (2004) at 25°C.
Above M ₂₀₀ : Tensile stress M ₂₀₀ in the elastomer at 200% elongation when measured according to JIS K6251 (2004) at 25°C. The elastomer according to any one of claims 1 to 6,
An elastomer having a tear strength of 25 N/mm or more at 25° C. when not stretched, as measured according to JIS K6252 (2001). The elastomer according to any one of claims 1 to 7,
An elastomer composed of silicone rubber. The elastomer according to any one of claims 1 to 8,
Elastomers containing inorganic fillers. The elastomer according to any one of claims 1 to 9,
Elastomers used in stretchable members for wearable devices. A wearable device comprising the elastomer according to any one of claims 1-10.

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