JP2022053560A - Wearable-device base - Google Patents

Abstract

To provide a wearable-device base having heat-insulating properties and moisture permeability.SOLUTION: The wearable-device base of the present invention includes a fluororubber foam, wherein the fluororubber foam comprises a crosslinked elastic fluorocopolymer, and the fluororubber foam has a content of interconnected voids of 20-70%.SELECTED DRAWING: None

Description

The present invention relates to a base material for a wearable device.

In recent years, so-called wearable devices that can be directly attached to a living body having a curved line have been actively developed. In a wearable device, an arithmetic element, a power feeding element, or the like is often installed on a base material for a wearable device. As a base material for a wearable device, a material that is flexible and does not easily deteriorate due to dirt such as sebum is suitable.

Fluorore-containing rubber is a material having excellent chemical resistance, oil resistance, etc., and is particularly suitable as a base material for wearable devices in that it is not easily deteriorated by stains such as sebum.
Examples of the fluorine-containing rubber include a cross-linked product of a copolymer having a unit based on vinylidene fluoride and a unit based on hexafluoropropylene, and a cross-linking of a copolymer having a unit based on tetrafluoroethylene and a unit based on propylene. A cross-linked product of a copolymer having a unit based on tetrafluoroethylene and a unit based on perfluoro (alkyl vinyl ether) is known.

Further, among the fluororubbers, fluorofoam rubber is known as a flexible material (Patent Document 1).

Japanese Patent No. 5967080

In a wearable device that is directly attached to a living body, heat generation when driving an arithmetic element or a power feeding element has become a problem. Therefore, by increasing the thickness of the base material between various elements and the living body and forming closed cells inside the base material, it is possible to improve the heat insulating property of the base material and reduce the influence of heat generation. can. However, since the moisture permeability is lowered by either method, the measurement accuracy may be lowered due to the excessive water content. Also, stuffiness impairs comfort. Especially when the wearable device is worn for a long time, these problems are considered to be remarkable.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a base material for a wearable device having heat insulating properties and moisture permeability.

The present invention has the following aspects.
[1] A wearable device having a fluorine-containing foam rubber, wherein the fluorine-containing foam rubber contains a crosslinked product of a fluorine-containing elastic copolymer, and the open cell ratio of the fluorine-containing foam rubber is 20 to 70%. Base material for.
[2] The base material for a wearable device according to [1], which has a bubble ratio of 20 to 90%.
[3] The fluorine-containing elastic copolymer contains a unit based on the fluorine-containing monomer, and the fluororesin-containing elastic copolymer contains a unit.
The fluorine-containing monomer is at least one selected from the group consisting of tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, a compound represented by the following formula (1), and chlorotrifluoroethylene [1]. ] Or the base material for a wearable device according to [2].
CF ₂ = CFOR _f ... (1)
However, in the formula (1), R _f is a perfluoroalkyl group having 1 to 9 carbon atoms or a perfluoro (oxaalkyl) group having 2 to 9 carbon atoms.
[4] The base material for a wearable device according to any one of [1] to [3], wherein the fluorine-containing foam rubber further contains an additive.
[5] The base material for a wearable device according to any one of [1] to [4], which has a thickness of 0.3 to 5 mm.
[6] A wearable device including the base material for a wearable device according to any one of [1] to [5].
[7] With respect to 100 parts by mass of the fluoroelastic copolymer, 0.5 to 10 parts by mass of a foaming agent, 0.05 to 10 parts by mass of a crosslinking agent, and 0 to 0.3 parts by mass of a crosslinking aid are contained. A fluoroelastic copolymer composition for producing a substrate for a wearable device, which comprises.
[8] The fluorine-containing elastic copolymer contains a unit based on the fluorine-containing monomer, and the fluorine-containing monomer is tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, represented by the following formula (1). The fluorine-containing elastic copolymer composition for producing a substrate for a wearable device according to [7], which is at least one selected from the group consisting of the compound to be used and chlorotrifluoroethylene.
CF ₂ = CFOR _f ... (1)
However, in the formula (1), R _f is a perfluoroalkyl group having 1 to 9 carbon atoms or a perfluoro (oxaalkyl) group having 2 to 9 carbon atoms.

According to the present invention, a base material for a wearable device having heat insulating properties and moisture permeability can be obtained.

In the present invention, the "fluorine-containing foam rubber" may be referred to as a fluorinated foam rubber molded body when emphasizing that it is a molded body.
Further, the oxaalkyl group means an alkyl group in which one or more carbon atoms (carbon atoms other than terminal carbon atoms) of the alkyl group are substituted with oxygen atoms. However, when the number of carbon atoms substituted with oxygen atoms is two or more, it is assumed that the carbon atoms substituted are not adjacent to each other. Further, the number of carbon atoms of the oxaalkyl group means the number not including the carbon atom substituted with the oxygen atom.
Further, the "unit" is an atomic group derived from one molecule of the monomer directly formed by polymerizing the monomer and an atomic group obtained by chemically converting a part of the atomic group. It is a generic term. The "monomer-based unit" is also simply referred to as "unit" below.

The base material for a wearable device of the present invention has a fluorine-containing foam rubber described later, and as described later, the open cell ratio of the fluorine-containing foam rubber is 20 to 70%.

<Fluorine-containing foam rubber bubbles>
The bubbles of the fluorine-containing foam rubber described later are classified into two types, "closed bubbles" and "open cells".

The closed cell is a bubble in a state where it is not connected to the external space of the fluorine-containing foam rubber. On the other hand, open cells are bubbles in a state of being connected to the external space of the fluorine-containing foam rubber.
In other words, in the following method for measuring the open bubble ratio, the bubbles whose inside is replaced with water are open bubbles, and the bubbles whose inside is not replaced by water are closed bubbles.

The high open cell ratio contributes to the moisture permeability of the fluorine-containing foam rubber. The open bubbles include bubbles in which only one place is connected to the external space, and such bubbles do not necessarily contribute to the moisture permeability of the fluorine-containing foam rubber, but include high open cell ratio. Fluorofoam rubber is considered to exhibit good moisture permeability by increasing the proportion of bubbles connecting the living body and the external space of the fluorine-containing rubber.

The bubble ratio Ft of the fluorine-containing foam rubber is preferably 20 to 90%, more preferably 20 to 85%, further preferably 30 to 80%, and most preferably 45 to 75%. As will be described later, the bubble ratio can be adjusted by, for example, the amount of foaming agent and cross-linking agent used, molding conditions such as molding temperature and molding time.

The bubble ratio Ft (%) of the fluorine-containing foam rubber is the ratio of the volume of bubbles to the volume V1 (apparent volume obtained from the outer dimensions) of the fluorine-containing foam rubber. The volume V1 was obtained from the thickness and area of the fluorinated foam rubber, and it was produced from a composition obtained by removing the foaming agent from the mass W1 of the fluorinated foam rubber and the fluorinated elastic copolymer composition which is the base of the fluorinated rubber. The bubble ratio Ft was calculated from the density D1 of the fluororubber using the formula (3).
Ft (%) = [1-{(W1 / D1) / V1}] × 100 ・ ・ ・ Equation (3)

The open cell ratio in the fluorine-containing foam rubber is 20 to 70%, more preferably 30 to 70%, still more preferably 40 to 65%. When the open cell ratio is 20% or more, the moisture permeability is excellent. When the open cell ratio is 70% or less, it is difficult to pass heat generated when the arithmetic element or the feeding element is driven, and it is difficult to cause burns, that is, excellent heat insulating property.

The open cell ratio Fo (%) of the fluorine-containing foam rubber can be obtained from the formula (4). A fluorine-containing foam rubber having a volume of V1 and a mass of W1 was fixed in water reduced to 50 mmHg and held for 5 minutes, then returned to normal pressure and held for 5 minutes, and the process was repeated twice to replace the gas in the open cells with water. bottom. The mass W2 of the fluorine-containing foam rubber after replacement with water was measured, and the open cell ratio Fo (%) was calculated. Dw is the specific gravity of water.
Fo (%) = [{(W2-W1) / (Dw × V1)] × 100 ・ ・ ・ Equation (4)

The closed cell ratio in the fluorine-containing foam rubber is preferably 0 to 70%, more preferably 5 to 65%, further preferably 5 to 55%, and most preferably 15 to 45%. When the closed cell ratio is 5% or more, the heat insulating property is excellent. When the closed cell ratio is 70% or less, it has moisture permeability.

The closed cell ratio Fc (%) of the fluorine-containing foam rubber can be obtained from the formula (5).
Fc (%) = Ft-Fo ・ ・ ・ Equation 5

As will be described later, the ratio of the open cell ratio to the closed cell ratio can be adjusted by adjusting the speeds of the foaming reaction and the cross-linking reaction, or by crushing the closed cells to form open cells.

Moisture permeability refers to the property of permeating water vapor. The degree of moisture permeability can be expressed by moisture permeability. Moisture permeability can be measured and calculated by the method specified in JIS Z0208. Specifically, when a sample having a thickness of 2 mm to be measured is used as a boundary surface at 40 ° C., the air on one side is kept dry at a relative humidity of 90%, and the air on the other side is kept dry by a hygroscopic agent. , The mass (g) of water vapor passing through the sample in 24 hours is determined, and the value converted per 1 m ² of the base material is defined as the moisture permeation.

The moisture permeability of the fluorine-containing foam rubber of the present invention is not particularly limited, but is preferably 50 g / ^m 2.24 h or more in consideration of comfort when worn. It is preferably 100 g / m 2.24 h or ^more , and more preferably ²⁰⁰ g / m 2.24 h or more. The moisture permeability of the fluorine-containing foam rubber can be appropriately designed by adjusting the bubble ratio, open cell ratio / closed cell ratio, thickness and the like.

<Fluorine-containing foam rubber>
The fluorinated foam rubber in the present invention contains a crosslinked product of a fluorinated elastic copolymer. The fluorine-containing foamed rubber is included in the fluoroelastic copolymer composition for foaming a base material for a wearable device, which will be described later, and for producing a base material for a wearable device. A fluorine-containing foam rubber obtained by cross-linking a fluorine-containing elastic copolymer is preferable.

<Fluorine-containing elastic copolymer composition for manufacturing a base material for wearable devices>
The fluorinated elastic copolymer composition for producing a base material for a wearable device of the present invention (hereinafter, also simply referred to as "fluorine-containing elastic copolymer composition") is used for producing a fluorinated elastic foam rubber. Therefore, it contains a fluorine-containing elastic copolymer, a foaming agent, and a cross-linking agent composed of a peroxide as essential components. It is preferable that no cross-linking aid is contained, or only a small amount of the cross-linking aid is contained. As the fluorine-containing elastic copolymer, only one kind may be used, or two or more kinds may be used in combination.

(Fluorine-containing elastic copolymer)
In the present invention, the fluorinated elastic copolymer is preferably a fluorinated elastic copolymer having a molecular weight of more than 2,000.

The fluorine-containing elastic copolymer in the present invention preferably has a glass transition point of 20 ° C. or lower, more preferably 10 ° C. or lower, and particularly preferably 5 ° C. or lower. Within the above range, the fluorine-containing foam rubber containing the fluorine-containing elastic copolymer has excellent flexibility, so that the wearable device including the base material for the wearable device of the present invention can be comfortably used even in a low temperature.

Further, the Mooney viscosity (LM _{1 + 4} 100 ° C.) at 100 ° C. according to JIS K6300 of the fluorine-containing elastic copolymer is preferably 1 to 200, more preferably 5 to 190, and particularly preferably 10 to 180.

[Fluorine-containing monomer]
The fluorinated elastic copolymer contains a unit based on the fluorinated monomer.
As the fluorine-containing monomer, tetrafluoroethylene (hereinafter, also referred to as TFE), vinylidene fluoride (hereinafter, also referred to as VdF), hexafluoropropylene (hereinafter, also referred to as HFP) may be used. There is), the compound represented by the following formula (1), and chlorotrifluoroethylene are preferably selected. When the unit based on the fluorine-containing monomer contained in the fluorine-containing elastic copolymer is a unit based on one or more kinds of fluorine-containing monomers selected from the group consisting of these monomers, the fluorine-containing elastic copolymer The polymer is preferable because it has excellent heat resistance and chemical resistance.

CF ₂ = CFOR _f ... (1)
In the formula (1), R _f is a perfluoroalkyl group having 1 to 9 carbon atoms or a perfluoro (oxaalkyl) group having 2 to 9 carbon atoms.

The compound represented by the formula (1) in which R _f is a perfluoroalkyl group (that is, a perfluoroalkyl vinyl ether) may be referred to as PAVE.
The compound represented by the formula (1) in which R _f is a perfluoro (oxaalkyl) group (that is, perfluoro (oxaalkyl vinyl ether)) may be referred to as POAVE.

R _f may be linear, may contain branches, or may have a cyclic structure. When R _f is a perfluoroalkyl group, the number of carbon atoms is preferably 1 to 6, and more preferably 1 to 4. When R _f is a perfluoro (oxaalkyl) group, the number of carbon atoms is preferably 2 to 8, and more preferably 2 to 6.

As specific examples of the perfluoroalkyl group as R _f , CF ₃ group, C ₂ F ₅ group, and C ₃ F ₇ group are preferable.
The number of oxygen atoms in the perfluoro (oxaalkyl) group as R _f is preferably 4 or less, and more preferably 2 or less. Specific examples of the perfluoro (oxaalkyl) group include C ₂ F ₅ OC ₂ F ₄ -group, C ₃ F ₇ OC ₃ F _6- group, and C ₃ F ₇ OC ₃ F ₆ OC ₃ F _6- group. Is preferable.

Specific examples of the compound represented by the formula (1) include CF ₂ = CFOCF ₃ (hereinafter, also referred to as PMVE), CF ₂ = CFOCF ₂ CF ₃ (hereinafter, also referred to as PEVE), and CF ₂ = CFOCF ₂ . CF ₂ CF ₃ (hereinafter also referred to as PPVE), CF ₂ = CFO (CF ₂ ) ₃ CF ₃ , CF ₂ = CFO (CF ₂ ) ₄ CF ₃ , CF ₂ = CFO CF ₂ OCF ₃ , CF ₂ = CFO CF ₂ CF ₂ OCF ₃ , CF ₂ = CFOCF ₂ CF ₂ OCF ₂ CF ₃ , CF ₂ = CFO (CF ₂ ) ₃ OCF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₃ , CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₂ CF ₃ , CF ₂ = CFO (CF ₂ CF ₂ O) ₂ CF ₂ CF ₃ , CF ₂ = CFO [CF ₂ CF (CF ₃ ) O] ₂ CF ₃ , CF ₂ = CFO [CF ₂ CF (CF ₃ ) O] ₂ (CF ₂ ) ₂ CF ₃ and the like.

[Hydrocarbon monomer]
The fluorinated elastic copolymer may further contain a unit based on the hydrocarbon monomer in addition to the unit based on the fluorinated monomer. The hydrocarbon monomer is composed of a hydrocarbon compound having a carbon-carbon unsaturated bond and containing no fluorine atom.

As the hydrocarbon monomer, the compound represented by the following formula (2), propylene (hereinafter, may be referred to as P) and ethylene (hereinafter, may be referred to as E) are preferable. Propylene is more preferred. The fluorine-containing elastic copolymer may contain two or more kinds of units based on these hydrocarbon monomers.

CH ₂ = CHOR ・ ・ ・ (2)
In the formula (2), R is an alkyl group having 1 to 8 carbon atoms or an oxaalkyl group having 2 to 8 carbon atoms. R may be linear, may contain branches, or may have a cyclic structure. The number of carbon atoms of the alkyl group is preferably 1 to 6, and more preferably 1 to 4. The number of carbon atoms of the oxaalkyl group is preferably 2 to 6, and more preferably 2 to 4. The number of oxygen atoms of the oxaalkyl group is preferably 1 or 2, more preferably 1.

Specific examples of the vinyl ether represented by the formula (2) include methyl vinyl ether (hereinafter, also referred to as MVE), ethyl vinyl ether (hereinafter, also referred to as EVE), and butyl vinyl ether (hereinafter, BVE). It may be described), methoxyethyl vinyl ether, ethoxyethyl vinyl ether and the like.

When the fluoroelastic copolymer contains a unit based on a hydrocarbon monomer, the total of the units based on the fluoromonomer and the unit based on the hydrocarbon monomer constituting the fluoroelastic copolymer. The ratio of the unit based on the hydrocarbon monomer is preferably 10 to 80 mol%, more preferably 20 to 70 mol%, and particularly preferably 30 to 60 mol% with respect to 100 mol%. When it is at least the lower limit of the above range, the hardness of the fluorine-containing foam rubber does not increase too much, and when it is at least the upper limit, heat resistance and chemical resistance are excellent.

[Crosslinkable group-containing monomer]
The fluorine-containing elastic copolymer in the present invention may contain a unit based on a crosslinkable group-containing monomer in addition to the unit based on the above-mentioned monomer. In the present specification, the crosslinkable group-containing monomer means a compound having one or more crosslinkable groups described later in the same molecule and having a molecular weight of 2,000 or less. The crosslinkable group in the crosslinkable group-containing monomer does not substantially react during the production of the fluoroelastic copolymer, and the fluoroelastic copolymer is derived from the crosslinkable group-containing monomer. Has a group.

The ratio of the units based on the crosslinkable group-containing monomer is preferably 0.001 to 10 mol%, preferably 0.001 to 5 mol%, based on 100 mol% of all the units constituting the fluoroelastic copolymer. Is more preferable, and 0.01 to 3 mol% is particularly preferable. When it is at least the lower limit of the above range, the crosslink density is sufficient and sufficient tensile strength is exhibited. When it is not more than the upper limit of the above range, it is easy to obtain a fluorine-containing foam rubber having a good balance of hardness, heat resistance, chemical resistance and the like.

Examples of the crosslinkable group in the crosslinkable group-containing monomer include a halogen atom, an acid anhydride residue, a carboxy group, an amino group, a cyano group, and a hydroxyl group. Of the crosslinkable groups, a halogen atom is preferable, and an iodine atom is particularly preferable.

Suitable specific examples of the crosslinkable group-containing monomer include (2-bromo-1,1,2,2-tetrafluoroethyl) trifluorovinyl ether and (2-iodo-1,1,2,2-tetra). Fluoroethyl) trifluorovinyl ether, vinyl crotonic acid, vinyl methacrylate, maleic anhydride, itaconic anhydride, maleic acid, itaconic acid, heptafluoro-4-pentenenitrile and the like can be mentioned. Two or more kinds of crosslinkable group-containing monomers can be used.

[Preferable Embodiment of Fluorine-Containing Elastic Copolymer]
Suitable embodiments of the fluoroelastic copolymer include, for example, TFE / P copolymer, TFE / P / VdF copolymer, TFE / HFP copolymer, VdF / HFP copolymer, TFE / VdF / HFP. Copolymers, TFE / PAVE-based polymers (specifically, TFE / PMVE copolymers, TFE / PPVE copolymers, TFE / PEVE copolymers, TFE / PMVE / PPVE copolymers), TFE / POAVE Polymers (specifically, TFE / CF ₂ = C (OC ₂ F ₅ ) ₂ copolymers), TFE / MVE copolymers, TFE / EVE copolymers, TFE / BVE copolymers, TFE / Examples thereof include EVE / BVE copolymers, VdF / PPVE copolymers, and E / HFP copolymers. Further, it is also preferable that these copolymers further contain a unit based on a crosslinkable group-containing monomer.

Of these, TFE / P copolymers, TFE / P / VdF copolymers, TFE / PAVE copolymers, VdF / HFP copolymers, and TFE / VdF / HFP copolymers are preferable. Further, it is also preferable that these copolymers further contain a unit based on a crosslinkable group-containing monomer.

In particular, TFE / P copolymers, TFE / P / VdF copolymers, VdF / HFP copolymers and TFE / VdF / HFP copolymers are more preferable in terms of the balance between tensile strength, heat resistance and chemical resistance. The TFE / P copolymer is most preferred.

The molar ratio of the unit based on each monomer in the above copolymer is not particularly limited and may be appropriately selected according to the required characteristics.

Preferable specific examples of the fluorine-containing elastic copolymer include the following copolymers.
TFE (40-60 mol%) / P (60-40 mol%) copolymer, TFE (20-79 mol%) / P (79-20 mol%) / VdF (1-50 mol%) polymer , TFE (20-80 mol%) / HFP (80-20 mol%) copolymer, VdF (50-95 mol%) / HFP (5-50 mol%) copolymer, TFE (1-35 mol%) ) / VdF (45-90 mol%) / HFP (5-50 mol%) copolymer, TFE (40-70 mol%) / PMVE (60-30 mol%) polymer, TFE (40-70 mol%) %) / PPVE (60-30 mol%) copolymer, TFE (40-70 mol%) / CF ₂ = C (OC ₂ F ₅ ) ₂ (60-30 mol%) copolymer, TFE (70-70- 30 mol%) / MVE (30-70 mol%) copolymer, TFE (70-30 mol%) / EVE (30-70 mol%) polymer, TFE (70-30 mol%) / BVE (30) ~ 70 mol%) Polymer, TFE (60-30 mol%) / EVE (1-69 mol%) / BVE (1-69 mol%) copolymer, VdF (40-70 mol%) / PPVE ( 60-30 mol%) copolymer, E (40-60 mol%) / HFP (60-40 mol%) copolymer. Further, a copolymer containing 0.001 to 10 mol% of the units based on the crosslinkable group-containing monomer in these copolymers is also preferable.

Here, the TFE (40 to 60 mol%) / P (60 to 40 mol%) copolymer contains TFE units and P units in a ratio of 40 to 60 mol%: 60 to 40 mol%. It means a polymer, and other copolymers have the same meaning.

Further, in the TFE (40 to 60 mol%) / P (60 to 40 mol%) copolymer, the copolymer content further contains 0.001 to 10 mol% of the units based on the cross-linking group-containing monomer with respect to all the units. In the copolymerization, the ratio of TFE unit to P unit is 40 to 60 mol%: 60 to 40 mol%, and the unit based on the cross-linking group-containing monomer is 0.001 to 10 mol% with respect to all units. It means a copolymer contained therein, and other copolymers have the same meaning.

[Method for Producing Fluorine-Containing Elastic Copolymer]
The method for producing the fluorine-containing elastic copolymer is not particularly limited, but emulsion polymerization, solution polymerization and the like can be preferably used, and emulsion polymerization is particularly preferable.

(Effervescent agent)
The foaming agent is not particularly limited, but an organic degradable chemical foaming agent is preferable, and an azo compound, a nitroso compound, and a hydrazine compound are more preferable. Specific examples of the organic degradable chemical foaming agent include azodicarbonamide, barium azodicarboxylate, N, N-dinitrosopentamethylenetetramine, benzenesulfonylhydrazine, and hydrazodicarbonamide. As the foaming agent, two or more of the above compounds may be used.

The content of the foaming agent in the fluoroelastic copolymer composition is 0.1 to 20 parts by mass, preferably 0.3 to 15 parts by mass, based on 100 parts by mass of the fluoroelastic copolymer. More preferably 0.5 to 10 parts by mass. Within this range, it is easy to obtain a composition that gives a fluorine-containing foam rubber having excellent bubble uniformity, surface smoothness of a molded product, heat resistance, and tensile strength.

(Crosslinking agent)
The fluorine-containing elastic copolymer composition contains a cross-linking agent composed of an organic peroxide. As the cross-linking agent, an organic peroxide is preferable. The organic peroxide is not particularly limited, but an organic peroxide having a 1-minute half-life temperature of 150 to 250 ° C., which is a temperature at which half the amount of the organic peroxide decomposes in 1 minute, is preferable, and 150 to 200 ° C. is preferable. More preferred.

Specific examples of the organic peroxide include tert-butyl peroxide, tert-butyl cumyl peroxide, dicumyl peroxide, α, α'-bis (tert-butyl peroxy) -p-diisopropylbenzene, 2 , 5-Dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane-3,1,3-bis (tert-butyl) Peroxyisopropyl) benzene, 1,1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxyperoxide, benzoylperoxide, tert- Examples thereof include butylperoxybenzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxymaleic acid, tert-butylperoxyisopropylcarbonate and the like. Two or more kinds of organic peroxides can be used.

The content of the organic peroxide in the fluorinated elastic copolymer composition is 0.05 to 10 parts by mass and 0.3 to 5 parts by mass with respect to 100 parts by mass of the fluorinated elastic copolymer. It is preferably 0.5 to 3 parts by mass, and more preferably 0.5 to 3 parts by mass. Within this range, it is easy to obtain a composition that gives a fluorine-containing foam rubber having excellent air bubble uniformity, surface smoothness of a molded body, heat resistance, and tensile strength.

(Crosslinking aid)
The fluorine-containing elastic copolymer composition for producing a base material for a wearable device of the present invention may contain a cross-linking aid. However, it is preferable that the fluorine-containing elastic copolymer composition does not contain a cross-linking aid, or even if it contains a cross-linking aid, it is contained in a small amount. As a result, it is possible to produce a fluorine-containing foam rubber having good foaming state, high elasticity, heat resistance and chemical resistance with good reproducibility.

The reason why such an effect is obtained is not clear, but it is presumed as follows. Usually, when cross-linking is performed without foaming, a relatively large amount of a cross-linking aid is added to improve the cross-linking density and obtain rubber having good physical characteristics. On the other hand, when foaming and cross-linking are performed at the same time, if the cross-linking density is increased by using a cross-linking aid, foaming is suppressed and becomes unstable. Therefore, it is considered that the foaming state is improved because the increase in the crosslinking density of the fluororubber at the time of crosslinking can be suppressed by using the composition which does not contain the crosslinking aid or contains a small amount.

The cross-linking aid in the fluorine-containing elastic copolymer composition is a compound having two or more reactive functional groups in the same molecule. Examples of the reactive functional group include a carbon-carbon double bond-containing group, a halogen atom, an acid anhydride residue, a carboxy group, an amino group, a cyano group and a hydroxyl group. The two or more reactive functional groups present in the same molecule of the cross-linking aid may be the same or different from each other.

Examples of the carbon-carbon double bond-containing group include an alkenyl group such as a vinyl group, an allyl group and a metalyl group, an unsaturated acyl group such as an acryloyl group and a methacryloyl group, and a maleimide group. A preferred carbon-carbon double bond-containing group is an alkenyl group having 2 to 4 carbon atoms, and an allyl group is particularly preferable.

Examples of cross-linking aids are triallyl cyanurate, triallyl isocyanurate, trimetalyl isocyanurate, 1,3,5-triacrylloylhexahydro-1,3,5-triazine, triallyl trimellitate, m-. Phenylene diamine bismaleimide, p-quinonedioxime, p, p'-dibenzoylquinonedioxime, dipropargyl terephthalate, diallyl phthalate, N, N', N'', N'''-tetraallyl terephthalamide, poly Examples thereof include vinyl group-containing siloxane oligomers such as methylvinylsiloxane and polymethylphenylvinylsiloxane.

When the fluoroelastic copolymer composition for producing a substrate for a wearable device of the present invention contains a cross-linking aid, the cross-linking aids include triallyl cyanurate, triallyl isocyanurate, and trimetalyl isocyanurate. It is more preferable to use one or more selected from the group consisting of. In particular, in terms of cross-linking reactivity, it is more preferable that the cross-linking aid is triallyl isocyanurate (TAIC), and it is particularly preferable to use only TAIC as the cross-linking aid.

When the cross-linking aid is contained, the content of the cross-linking aid is preferably 0.4 parts by mass or less, more preferably 0.1 parts by mass or less, based on 100 parts by mass of the fluoroelastic copolymer composition. .. When the content of the cross-linking aid is 0.4 parts by mass or less, the fluoroelastic copolymer composition is foamed and the fluoroelastic copolymer contained in the fluoroelastic copolymer composition is crosslinked. The resulting fluorofoamed rubber has excellent foaming uniformity and surface smoothness. Further, the fluorine-containing foam rubber is excellent in physical properties such as tensile breaking strength, and is also excellent in heat resistance and chemical resistance. The lower limit of the content of the cross-linking aid is preferably 0.001 part by mass or more, more preferably 0.005 part by mass or more, and 0.01 part by mass with respect to 100 parts by mass of the fluoroelastic copolymer composition. The above is the most preferable. Within this range, the fluorine-containing foam rubber has excellent physical properties and excellent heat resistance and chemical resistance due to the inclusion of the cross-linking aid.
It is most preferable that the fluoroelastic copolymer composition for producing a base material for a wearable device of the present invention does not contain a cross-linking aid.

(Additive)
The fluorine-containing elastic copolymer composition may contain additives other than the foaming agent, the cross-linking agent, and the cross-linking aid, if necessary. Examples of the additive include pigments, fillers, reinforcing agents, processing aids, and acid receiving agents. In addition, other known additives can be contained. When the fluoroelastic copolymer composition contains an additive that does not disappear in the foaming reaction and the crosslinking reaction, the fluoroelastic copolymer composition is foamed and contained in the fluoroelastic copolymer composition. The fluorofoamed rubber obtained by cross-linking the fluorofoam-containing elastic copolymer contains an additive.

Specific examples of the pigment include unsubstituted quinacridone, dimethylquinacridone, anthracinoyl red, polyazo yellow, benzimidazolone yellow, copper phthalocyanine blue, copper phthalocyanine green, cobalt phthalocyanine blue and the like. The content of the pigment is preferably 0.1 to 50 parts by mass with respect to 100 parts by mass of the fluoroelastic copolymer.

Specific examples of the filler include clay, talc and the like. The content of the filler is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the fluoroelastic copolymer.

Specific examples of the reinforcing agent include carbon black, carbon nanotube, titanium oxide, silicon dioxide, and polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, TFE / ethylene copolymer, and TFE /. Examples thereof include fluororesins such as hexafluoropropylene copolymers and TFE / perfluoro (alkyl vinyl ether) copolymers, foams, and porous members such as fiber aggregates obtained by assembling fibers into a non-woven fabric. The melting temperature of the fluororesin is preferably more than 20 ° C. The content of the reinforcing agent is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the fluoroelastic copolymer.

In the present invention, the term “porous” means a structure containing at least 10, preferably 100 or more, and more preferably 1,000 or more pores per 1 ^cm3 of volume. The pores may have a continuous structure or an independent structure.

As the processing aid, stearic acid and salts thereof are preferable. Specific examples of the stearate include sodium stearate, potassium stearate, calcium stearate, and magnesium stearate. Two or more kinds of stearic acid and its salts can be used.

The content of the processing aid is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 3 parts by mass with respect to 100 parts by mass of the fluoroelastic copolymer.

Examples of the acid receiving agent include metal oxides and metal carbonic acid compounds. Specific examples of the metal oxide include ZnO, MgO, CaO, TiO ₂ , CuO, and BaO. Specific examples of the metal carbonate compound include ZnCO ₃ , MgCO ₃ , and CaCO ₃ . The content of the acid receiving agent is preferably 0 to 5 parts by mass with respect to 100 parts by mass of the fluoroelastic copolymer.

<Method for manufacturing a fluoroelastic copolymer composition for manufacturing a base material for a wearable device>
The fluorine-containing elastic copolymer composition for producing a base material for a wearable device of the present invention can be obtained by mixing the above components. As a mixing method, various mixing methods can be applied, but a method of kneading using a two-roll, a kneader, a Banbury mixer or the like is preferable. If the heat generated during kneading is intense, it is preferable to cool the kneader such as a roll. The kneading temperature is preferably 100 ° C. or lower, more preferably 80 ° C. or lower. If the kneading temperature exceeds 100 ° C., a foaming reaction and / or a crosslinking reaction may occur. The lower limit of the kneading temperature is not particularly limited, but is usually 20 ° C.

<Manufacturing method of fluorine-containing foam rubber>
The fluorofoamable rubber of the present invention foams the fluoroelastic copolymer composition for producing a base material for a wearable device of the present invention, and the fluoroelastic copolymer composition contains the fluoroelastic copolymer composition. It is preferably obtained by cross-linking the coalescence. When the fluoroelastic copolymer composition is foamed and the fluoroelastic copolymer contained in the fluoroelastic copolymer composition is crosslinked, not only in the case of low bubble ratio but also in the case of high bubble of 80% or more. Even if the ratio is high, a uniform and good foamed state can be obtained, and a fluorine-containing foamed rubber having good physical properties can be obtained.

When the fluoroelastic copolymer composition is heated to a temperature equal to or higher than the decomposition temperature of the foaming agent, a foaming reaction occurs, and when the composition is heated to a temperature equal to or higher than the decomposition temperature of the cross-linking agent, a cross-linking reaction occurs. In the present invention, it is preferable to heat the foaming agent to a temperature equal to or higher than the decomposition temperature of the foaming agent and higher than the decomposition temperature of the cross-linking agent to simultaneously carry out the foaming reaction and the cross-linking reaction. These heatings may be performed under pressure or under normal pressure.

At this time, the ratio of the closed cells and the open cells of the fluorine-containing foam rubber can be controlled by adjusting the speeds of the foaming reaction and the crosslinking reaction. By slowing the foaming reaction with respect to the crosslinking reaction, a molded product having many closed cells can be obtained. Further, if foaming is started while the crosslinking reaction rate is low, a molded product having many open cells can be obtained, and if foaming is started at a stage where the crosslinking reaction rate is sufficiently high, a molded product having many closed cells can be obtained.

Further, the closed cells may be crushed when pressure is applied by, for example, a roll, and the crushed open cells may become open cells.

The heating temperature of the fluorinated elastic copolymer composition at the time of producing the fluorinated foam rubber is preferably in the range of 100 to 300 ° C. When heated in this temperature range, the foaming reaction and the crosslinking reaction proceed in a well-balanced manner, and a fluorine-containing foam rubber having excellent uniformity in the foamed state can be obtained. When molded under pressure, a fluorine-containing foam rubber molded body having excellent surface smoothness can be obtained. Further, a fluorine-containing foam rubber having excellent physical properties such as tensile breaking strength and excellent heat resistance and chemical resistance can be obtained.

Further, when the primary heating at a relatively low temperature and the secondary heating at a relatively high temperature are combined, a better foaming state can be easily obtained. The primary heating temperature is preferably 100 to 250 ° C. The secondary heating temperature is higher than the primary heating temperature, and the secondary heating temperature is preferably 150 to 300 ° C, more preferably 150 to 250 ° C, and most preferably 170 to 250 ° C. The secondary heating temperature is preferably 10 ° C. or higher higher than the primary heating temperature, and more preferably 20 ° C. or higher. Further, the secondary heating can be performed by gradually raising the temperature from the temperature of the primary crosslink. The heating time may be appropriately selected.

As a specific example of the combination of the primary heating and the secondary heating, the foamed fluororubber molded product obtained after performing primary heating for 3 to 60 minutes with a hot press at 150 to 200 ° C. to perform foaming, crosslinking and molding. Is preferably heated in an oven at 170 to 250 ° C., which is higher than the hot press temperature, for 1 to 24 hours to further promote the crosslinking reaction.

The bubble ratio of the fluoroelastic copolymer composition after the primary heating during the secondary heating is preferably 10 to 80%, more preferably 15 to 75%, and even more preferably 30 to 60%. The bubble ratio of the fluorine-containing foam rubber after the secondary heating during the secondary heating is preferably 10 to 80%, more preferably 15 to 75%, and even more preferably 30 to 60%.

A fluorine-containing foamed rubber molded product may be obtained by molding at the same time as foaming so that the shape becomes a predetermined shape when the foaming reaction is completed. The cross-linking reaction may be carried out at the same time as molding, or may be carried out after molding. The molding method is not particularly limited, and examples thereof include various molding methods such as pressure molding, compression molding, extrusion molding, and injection molding.
Further, it is also possible to further cut out a fluorine-containing foamed rubber molded product (for example, a sheet-shaped molded product) after foaming and cross-linking into a predetermined shape for molding.

The thickness of the fluorine-containing foam rubber for the base material for wearable devices is preferably 0.1 mm to 5 mm, more preferably 0.3 mm to 4 mm, and most preferably 0.5 mm to 2 mm.
When it is at least the lower limit of the above range, a fluorine-containing foam rubber for a base material for a wearable device having sufficient tensile strength can be obtained. When it is not more than the upper limit of the above range, it is excellent in moisture permeability and followability to a living body.

A skin layer may be present on the surface of the fluorine-containing foam rubber molded product. The presence of a skin layer makes it feel better and more comfortable.

<Manufacturing method of base material for wearable devices>
The base material for a wearable device of the present invention may be a laminate of a fluorine-containing foam rubber and another member. As the other member, a porous member such as a fiber assembly obtained by assembling a foam or a fiber into a non-woven fabric is preferable from the viewpoint of moisture permeability. The definition of the porous member is as described above. Further, the porous member may be arranged between a plurality of fluorine-containing foamed rubbers.

The base material for a wearable device of the present invention may have an adhesive layer on the surface on the living body side as long as the moisture permeability is not impaired.

The moisture permeability of the base material for a wearable device of the present invention is not particularly limited, but can be 50 g / ^m 2.24 h or more in consideration of comfort when worn. It is preferably 100 g / m 2.24 h or ^more , and more preferably ²⁰⁰ g / m 2.24 h or more. It can be appropriately designed by adjusting the material, thickness, etc. of the base material.

The thickness of the base material for a wearable device is preferably 0.3 mm to 10 mm, more preferably 0.5 mm to 5 mm, and most preferably 0.5 mm to 3 mm.
When it is at least the lower limit of the above range, a base material for a wearable device having sufficient tensile strength can be obtained. When it is not more than the upper limit of the above range, the wearable device base material is excellent in moisture permeability and followability to a living body.

According to the present invention, by using a fluorine-containing foam rubber, it is not easily deteriorated by dirt such as sebum, and has excellent heat resistance, chemical resistance, oil resistance, heat insulation, moisture permeability, and flexibility. It is possible to obtain a base material for a wearable device that is comfortable to use and has high comfort.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. The following methods were used as the measurement method and the evaluation method.
The method for measuring the bubble ratio, the method for measuring the open bubble ratio, and the method for calculating the closed bubble ratio are as described above.

[Tension strength]
A sheet-shaped fluorine-containing foam rubber molded body having a thickness of 2 mm was punched out with a No. 3 dumbbell as a sample, and the tensile strength was measured according to JIS K6251. 5 kg / cm ² or more was marked with ◯, and less than 5 kg / cm ² was marked with x.

[chemical resistance]
-Ethanol test A rubber sheet with a thickness of 2 mm cut into 30 mm squares was immersed in ethanol at 50 ° C. for 12 hours, the surface was wiped off, and the rate of change in the mass of the sheet before and after immersion was measured. A rate of change of less than 3% was evaluated as "○", a rate of change of 3% or more and less than 5% was evaluated as "Δ", and a rate of change of 5% or more was evaluated as "×".

-Hand cream test A hand cream containing 10% by mass of urea was applied to the surface of a rubber sheet cut into 30 mm squares, allowed to stand at 40 ° C. for 24 hours, and then the cream was removed and the appearance of the rubber was observed. Those with no change in appearance were evaluated as "○", and those with cloudiness on the appearance were evaluated as "x".

[Moisture permeability]
The measuring method is as described above. Moisture permeability was measured using a rubber sheet with a thickness of ² mm, and 100 g / m 2.24 h or more was "○", 50 g / m 2.24 h or ^more , 100 g / m less ^than 2.24 h was "△", 50 g / m. Less ^than 2.24 hours was evaluated as "x".

[Thermal insulation properties]
After placing a rubber sheet having a thickness of 5 mm on a hot plate heated to 100 ° C. for 30 minutes, the temperatures of the lower surface of the sheet (hot plate side) and the upper surface of the sheet (atmosphere side) were measured. A temperature difference of 50 ° C. or higher between the upper surface and the lower surface was evaluated as “◯”, and a temperature difference of less than 50 ° C. was evaluated as “x”.

Each component shown in the table is as follows.
-TFE / P copolymer: Fluorine-containing elastic copolymer (TFE unit / P unit molar ratio = 55/45), Mooney viscosity 60. The TFE / P copolymer is obtained by conventional emulsion polymerization, eg, the method described in Japanese Patent No. 5061446.
-TFE / VdF / HFP copolymer: manufactured by Solvay Solexis, product name: Tetrafluoroethylene P959. Mooney viscosity 65.
-Reinforcing agent: Carbon black, manufactured by Ashland, product name: MT-Carbon United N990.
-Crosslinking aid: Triallyl isocyanurate (TAIC).
-Crosslinking agent: A mixture of 40% by mass of 1,3-bis (tert-butylperoxyisopropyl) benzene and 60% by mass of calcium carbonate, manufactured by Kayaku Akzo Corporation, product name: Parkadox 14.
-Foaming agent: manufactured by Ichii Co., Ltd., product name: VP # 600.
The composition is 50 parts by mass of azodicarbonamide, 40 parts by mass of complex zinc oxide (composition of ZnO and CaCO ₃ manufactured by Yonejo Lime Co., Ltd.), 10 parts by mass of uric acid, and naphthenic oil (product name: manufactured by Idemitsu Kosan Co., Ltd.). , NP-24) (total 105 parts by mass).
-Processing aid: Sodium stearate.
-Acidants: Zinc oxide, ZnO.

(Example 1)
With the formulations shown in Table 1, all the components were kneaded with two rolls to obtain a fluorine-containing elastic copolymer composition. In Example 1, a TFE / P copolymer was used as the fluorine-containing elastic copolymer. This fluorine-containing elastic copolymer composition was first crosslinked by hot pressing at 170 ° C. for 20 minutes, and further secondarily crosslinked at 200 ° C. for 4 hours to obtain a fluorine-containing foam rubber having a thickness of 2 mm.
Table 1 shows the results of measurement and evaluation of the physical properties of this fluorine-containing foam rubber.

(Examples 2 to 5)
Fluorine-containing foam rubber was obtained by the same method as in Example 1 with the formulations shown in Table 1. The same evaluation and measurement as in Example 1 were performed. The results are shown in Table 1.

(Example 6)
In Example 6, AFLAS 100S (manufactured by AGC) was used as the fluorine-containing elastic copolymer, and the same evaluation and measurement as in Example 1 were performed. The results are shown in Table 1. Since the fluorinated elastic copolymer composition of Example 6 does not contain a foaming agent, the fluorinated rubber produced from the fluorinated elastic copolymer composition is not foamed.

(Example 7)
In Example 7, a silicone rubber sheet (2-9320) (obtained from AS ONE) was used instead of the fluorine-containing elastic copolymer, and the same evaluation and measurement as in Example 1 were performed. The results are shown in Table 1. The silicone rubber sheet of Example 7 is not foamed.

(Example 8)
About (urethane foam)
In Example 8, a low-resilience urethane sheet (KTHU-3015) (obtained from AS ONE) was used instead of the fluorine-containing elastic copolymer, and the same evaluation and measurement as in Example 1 were performed. The results are shown in Table 1. The low-resilience urethane sheet of Example 8 is foamed.
However, since the urethane foam is a commercially available product, the value corresponding to D1 (the density of urethane when not foamed) is unknown, so that the bubble ratio Ft and the closed cell ratio Fc could not be calculated.

As shown in Table 1, in Examples 1, 2 and 3 in which the open cell ratio was 20% or more and 70% or less, a base material for a wearable device having excellent moisture permeability and heat resistance was obtained.
On the other hand, in Example 4 in which the open cell ratio was 70 or more, a base material for a wearable device having excellent heat insulating properties could not be obtained.
Further, in Example 5 in which the open cell ratio was 20% or less, a base material for a wearable device having excellent moisture permeability could not be obtained.
In Examples 6 and 7 using a non-foaming material, a base material for a wearable device having excellent heat insulating properties could not be obtained.
In Example 8 having no fluorine-containing foam rubber, a base material for a wearable device having excellent chemical resistance could not be obtained.

The foamed fluororubber of the present invention can be suitably used as a base material for a wearable device.

Claims (8)

Has fluorine-containing foam rubber,
The fluorine-containing foam rubber contains a crosslinked product of a fluorine-containing elastic copolymer.
A base material for a wearable device in which the open cell ratio of the fluorine-containing foam rubber is 20 to 70%. The base material for a wearable device according to claim 1, wherein the bubble ratio is 20 to 90%. The fluorinated elastic copolymer contains a unit based on the fluorinated monomer and contains a unit.
Claimed that the fluorine-containing monomer is at least one selected from the group consisting of tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, a compound represented by the following formula (1), and chlorotrifluoroethylene. The base material for a wearable device according to 1 or 2.
CF ₂ = CFOR _f ... (1)
However, in the formula (1), R _f is a perfluoroalkyl group having 1 to 9 carbon atoms or a perfluoro (oxaalkyl) group having 2 to 9 carbon atoms. The base material for a wearable device according to any one of claims 1 to 3, wherein the fluorine-containing foam rubber further contains an additive. The base material for a wearable device according to any one of claims 1 to 4, which has a thickness of 0.3 to 5 mm. A wearable device comprising the base material for a wearable device according to any one of claims 1 to 5. Wearable containing 0.5 to 10 parts by mass of a foaming agent, 0.05 to 10 parts by mass of a cross-linking agent, and 0 to 0.3 parts by mass of a cross-linking aid with respect to 100 parts by mass of the fluoroelastic copolymer. A fluoroelastic copolymer composition for producing a base material for a device. The fluorinated elastic copolymer contains a unit based on the fluorinated monomer and contains a unit.
Claimed that the fluorine-containing monomer is at least one selected from the group consisting of tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, a compound represented by the following formula (1), and chlorotrifluoroethylene. 7. The fluoroelastic copolymer composition for producing a substrate for a wearable device according to 7.
CF ₂ = CFOR _f ... (1)
However, in the formula (1), R _f is a perfluoroalkyl group having 1 to 9 carbon atoms or a perfluoro (oxaalkyl) group having 2 to 9 carbon atoms.