JP2020125491A - Sealant rubber material and sealant including the same - Google Patents

Abstract

To obtain a sealant that has stable antistatic performance and has excellent discriminability.SOLUTION: A sealant rubber material contains an uncrosslinked crosslinkable fluorine rubber, an ionic liquid, and a crosslinker, and contains no carbon black.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a rubber material for a sealing material and a sealing material using the same.

It is known that a sealing material made of fluororubber contains a conductive material to prevent its charging. For example, Patent Document 1 discloses a sealing material formed of a rubber composition in which a conductive additive such as acetylene black or Ketjen black is mixed with fluororubber.

JP, 2007-137977, A

In the case of a rubber composition containing a conductive additive such as acetylene black or Ketjen black, the electrical characteristics are not stable due to the dispersed state of the conductive additive, and semiconductor manufacturing requires cleanliness because it contains many metal impurities. There is a problem that it is difficult to use for equipment and food related applications. There is also a problem that it cannot be used for applications requiring identification because of its black color.

An object of the present invention is to obtain a sealing material having stable antistatic performance and excellent identification.

The present invention is a rubber material for a sealing material, which contains an uncrosslinked crosslinkable fluororubber, an ionic liquid, and a crosslinking agent, and does not contain carbon black.

The present invention is a sealing material formed of a rubber composition in which the crosslinkable fluororubber of the rubber material for a sealing material of the present invention is crosslinked.

According to the present invention, since the ionic liquid is contained, the sealant obtained can have stable antistatic performance and excellent distinguishability.

Hereinafter, embodiments will be described in detail.

The rubber material for a sealing material according to the embodiment is preferably used for manufacturing a sealing material, in particular, a sealing material such as an O-ring used in a semiconductor manufacturing apparatus that uses plasma such as an etching apparatus and a plasma CVD apparatus. Is.

The rubber material for a sealing material according to the embodiment contains an uncrosslinked crosslinkable fluororubber, an ionic liquid, and a crosslinking agent.

Examples of the crosslinkable fluororubber include tetrafluoroethylene (TFE) polymer (PTFE), vinylidene fluoride (VDF) polymer (PVDF), vinylidene fluoride (VDF) and hexafluoropropylene (HFP). Copolymer (binary FKM), vinylidene fluoride (VDF), hexafluoropropylene (HFP) and tetrafluoroethylene (TFE) copolymer (ternary FKM), tetrafluoroethylene (TFE) and propylene (Pr) copolymer (FEP), vinylidene fluoride (VDF), propylene (Pr) and tetrafluoroethylene (TFE) copolymer, ethylene (E) and tetrafluoroethylene (TFE) copolymer Polymer (ETFE), copolymer of ethylene (E) and tetrafluoroethylene (TFE) and perfluoromethyl vinyl ether (PMVE), vinylidene fluoride (VDF) and tetrafluoroethylene (TFE) and perfluoromethyl vinyl ether ( Copolymer with PMVE), Copolymer with tetrafluoroethylene (TFE) and perfluoromethyl vinyl ether (PMVE) (FFKM), Copolymer with vinylidene fluoride (VDF) and perfluoromethyl vinyl ether (PMVE) Etc. As the crosslinkable fluororubber, it is preferable to use one kind or two or more kinds thereof, and it is more preferable to use a ternary FKM. When the crosslinkable fluororubber is peroxide-crosslinked, it preferably has iodine or bromine in the molecule.

The ionic liquid is a salt composed of a cation component and an anion component and has a melting point of 100° C. or lower.

Examples of the cation component of the ionic liquid include 1-ethyl-3-methylimidazolium, 1-methyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-octyl-3-methylimidazolium, 1-methyl-2,3-dimethylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-hexyl-2,3-dimethylimidazolium, 1-octyl- Imidazolium cations such as 2,3-dimethylimidazolium; 1-octyl-4-methyl-pyridinium, 1-methyl-pyridinium, 1-butyl-pyridinium, pyridinium-based cations such as 1-hexyl-pyridinium; tributylmethylammonium And aliphatic amine cations; pyrazolium cations and the like.

Examples of the anion component include bisfluorosulfonylimide-based anions such as bisfluorosulfonylimide, bistrifluoromethanesulfonylimide, and bistrifluorobutanesulfonylimide; fluorinated sulfonic acid systems such as tetrafluoroborate, hexafluoroborate, and trifluoromethanesulfonate. Anions; fluorinated carboxylic acid anions such as trifluoroacetic acid; thiocyanate anions; dicyanamide anions; tetracyanoborate anions.

The ionic liquid preferably contains one or more kinds of these cation components and one or more kinds of anion components. The cation component of the ionic liquid is preferably an imidazolium cation, a pyridinium cation, or an aliphatic amine cation. The cation component of the ionic liquid is preferably 1-ethyl-3-methylimidazolium for the imidazolium cation, 1-octyl-4-methyl-pyridinium for the pyridinium cation, and tributyl for the aliphatic amine cation. Methylammonium is preferred. The anion component of the ionic liquid is preferably a bisfluorosulfonylimide anion, of which bistrifluoromethanesulfonylimide and bistrifluorobutanesulfonylimide are more preferable.

The content of the ionic liquid in the rubber material for a sealing material according to the embodiment is preferably 0.01 parts by mass or more and 10 parts by mass or less, and more preferably 0.1 parts by mass or more with respect to 100 parts by mass of the crosslinkable fluororubber. It is 5 parts by mass or less.

As the cross-linking agent, peroxide is used if it is a peroxide cross-linking system, polyol is used if it is a polyol cross-linking system, and amine is used if it is an amine cross-linking system. The rubber material for the sealing material according to the embodiment is a peroxide cross-linking system. However, it is preferable to contain peroxide as a crosslinking agent.

Examples of peroxides of the cross-linking agent include 1,1-bis(t-butylperoxy)-3,5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroperoxide and di-t. -Butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, α,α-bis(t-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di(t-butyl) Peroxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3, benzoyl peroxide, t-butylperoxybenzene, t-butylperoxymaleic acid, t-butyl Examples include peroxyisopropyl carbonate and t-butyl peroxybenzoate. As the peroxide of the cross-linking agent, it is preferable to use one kind or two or more kinds thereof, and it is more preferable to use 2,5-dimethyl-2,5-di(t-butylperoxy)hexane.

The content of peroxide of the crosslinking agent in the rubber material for a sealant according to the embodiment is preferably 0.5 parts by mass or more and 10 parts by mass or less, and more preferably 1 part by mass with respect to 100 parts by mass of the crosslinkable fluororubber. It is above 5 parts by mass.

The rubber material for a sealing material according to the embodiment may further contain a crosslinking aid. Examples of the cross-linking aid include triallyl cyanurate, trimethallyl isocyanurate, triallyl isocyanurate, triacrylic formal, triallyl trimellitate, N,N′-m-phenylene bismaleimide, dipropargyl terephthalate, diallyl. Phthalate, tetraallyl terephthalate amide, triallyl phosphate, bismaleimide, fluorinated triallyl isocyanurate (1,3,5-tris(2,3,3-trifluoro-2-propenyl)-1,3,5-triazine -2,4,6-trione), tris(diallylamine)-S-triazine, triallyl phosphite, N,N-diallylacrylamide, 1,6-divinyldodecafluorohexane, hexaallylphosphoramide, N,N, N',N'-tetraallylphthalamide, N,N,N',N'-tetraallylmalonamide, trivinylisocyanurate, 2,4,6-trivinylmethyltrisiloxane, tri(5-norbornene-2) -Methylene) cyanurate, triallyl phosphite and the like. As the crosslinking aid, it is preferable to use one kind or two or more kinds thereof, and it is more preferable to use triallyl isocyanurate.

The content of the crosslinking aid in the rubber material for a sealing material according to the embodiment is preferably 0.1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the crosslinkable fluororubber.

The rubber material for a sealing material according to the embodiment may contain a silicone rubber or the like which is a rubber component other than the crosslinkable fluororubber. Further, the rubber material for a sealing material according to the embodiment contains a reinforcing material such as carbon black or silica, a plasticizer, a processing aid, a vulcanization accelerator, an antioxidant, etc., depending on the use of the sealing material to be manufactured. May be. However, in the case of manufacturing a sealing material used in a semiconductor manufacturing apparatus where the generation of particles in a plasma atmosphere poses a problem, the content of powdery or granular inorganic filler such as carbon black, silica, metal oxides, etc. Is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, still more preferably 3 parts by mass or less, and most preferably 0 parts by mass (not blended) with respect to 100 parts by mass of the crosslinkable fluororubber. Further, in the case of a sealing material used in a semiconductor manufacturing apparatus in which generation of particles in a plasma atmosphere poses a problem, a crosslinkable fluororubber composition in which a crosslinkable fluororubber is blended with a perfluoroelastomer having two or more alkenyl groups. Is preferably used.

The rubber material for a sealant according to the embodiment can be manufactured using an open type rubber kneader such as an open roll or a closed type rubber kneader such as a kneader.

According to the uncrosslinked rubber composition according to the embodiment having the above-mentioned configuration, since the ionic liquid is contained, the obtained sealing material can obtain stable antistatic performance and excellent distinguishability.

Next, an example of a method of manufacturing a sealing material using the rubber material for a sealing material according to the embodiment will be described.

In the production of the sealing material, first, a predetermined amount of the rubber material for a sealing material according to the embodiment is filled in a cavity of a mold preheated to a predetermined molding temperature, and then the mold is clamped, and then the predetermined molding is performed in that state. The pressure is maintained for a predetermined molding time for primary thermal crosslinking. This molding may be press molding or injection molding. The molding temperature is, for example, 150° C. or higher and 180° C. or lower. The molding pressure is, for example, 0.1 MPa or more and 25 MPa or less. The molding time is, for example, 3 minutes or more and 20 minutes or less.

Next, after opening the mold and taking out the molded product, it is placed in a heating furnace in which the inside of the furnace has been preheated to a predetermined heating temperature, and in that state, it is held for a predetermined heating time for the secondary heating. Crosslink. The heating temperature is, for example, 200° C. or higher and 300° C. or lower. The heating time is, for example, 1 hour or more and 48 hours or less.

Then, after the molded product is taken out from the heating furnace, it is irradiated with radiation to crosslink the radiation, if necessary. Examples of the radiation include α rays, β rays, γ rays, electron beams, and ions. As the radiation, it is preferable to use an electron beam or γ-ray of these. The irradiation dose of radiation is preferably 10 kGy or more and 100 kGy or less, and more preferably 30 kGy or more and 80 kGy or less from the viewpoint of enhancing plasma resistance.

In this way, the sealing material formed of the rubber composition in which the crosslinkable fluororubber of the rubber material for a sealing material according to the embodiment is crosslinked is obtained.

The volume resistivity of the rubber composition forming the sealing material is preferably 1.0×10 ¹³ Ω·cm or less, more preferably 1.0×10 ¹² Ω·cm or less. These surface resistivity and volume resistivity are measured based on JISK6271-1:2015.

The half-life of the charging property test of the rubber composition forming the sealing material is preferably 2.0 seconds or less, more preferably 1.0 second or less. The half-life of this charging property test is measured according to the method A (half-life measurement method) defined in JIS L1094:2014.

The compression set of the rubber composition forming the sealing material is preferably 30.0% or less. This compression set is measured based on JISK6262:2013 with a test time of 72 hours and a test temperature of 150°C.

(Rubber composition)
The rubber compositions of Examples 1 to 15 and Comparative Examples 1 to 11 below were produced. The respective configurations are also shown in Tables 1 to 4.

<Example 1>
Crosslinkable fluororubber A Peroxide crosslinking ternary FKM (Technoflon P459 SOLVAY Co., Ltd.) was mixed with 100 parts by weight of this crosslinkable fluororubber A, 1-ethyl-3-methylimidazolium of ionic liquid A. Bistrifluoromethanesulfonyl imide (EMI-N111 manufactured by Mitsubishi Materials Corporation) 1.0 part by mass, peroxide 2,5-dimethyl-2,5-di(t-butylperoxy)hexane as a crosslinking agent (Perhexa 25B NOF (Manufactured by the company) and 4.0 parts by mass of triallyl isocyanurate (manufactured by Taiki Nippon Kasei Co., Ltd.) as a cross-linking aid, and kneaded to prepare an uncrosslinked rubber composition. Subsequently, this uncrosslinked rubber composition was press-molded at a molding temperature of 165° C., a molding pressure of 5 MPa, and a molding time of 15 minutes for primary thermal crosslinking, and then subjected to a secondary heat treatment at a heating temperature of 200° C. and a heating time of 4 hours. Cross-linking was performed to obtain a sheet-shaped rubber composition. Then, this sheet-shaped rubber composition was irradiated with γ-rays with an irradiation dose of 30 kGy to be radiation-crosslinked. The sheet-shaped rubber composition produced by irradiating this γ ray was set as Example 1.

<Examples 2 to 9>
Instead of the ionic liquid A, 1-ethyl-3-methylimidazolium bistrifluorobutanesulfonyl imide of ionic liquid B (EMI-N441 manufactured by Mitsubishi Materials Corp.) and 1-butyl-3-methylimidazolium of ionic liquid C, respectively. -Bistrifluoromethanesulfonylimide (BMI-N111 manufactured by Mitsubishi Materials), ionic liquid D 1-butyl-3-methylimidazolium bistrifluorobutanesulfonylimide (BMI-N441 manufactured by Mitsubishi Materials), ionic liquid E-1 -Ethyl-3-methylimidazolium bisfluorosulfonyl imide (Elexel AS-110 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), 1-ethyl-3-methylimidazolium bistrifluoromethanesulfonyl imide of ionic liquid F (Electel AS-210 Dai-ichi Kogyo Seiyaku Co., Ltd., ionic liquid G 1-octyl-4-methylpyridinium bisfluorosulfonylimide (Elexel AS-804 Dai-ichi Kogyo Seiyaku Co., Ltd.), ionic liquid H (Elexel MP-457 Daiichi Kogyo) (Manufactured by Pharmaceuticals Co., Ltd.) and ionic liquid I tributylmethylammonium bistrifluoromethanesulfonylimide (manufactured by FC-4400 3M Japan Co., Ltd.) except that a sheet-shaped rubber produced by the same operation as in Example 1 was used. The compositions were Examples 2-9.

<Examples 10 to 13>
Except that the mixing amount of the ionic liquid C was 0.1 parts by mass, 0.5 parts by mass, 1.5 parts by mass, and 2.0 parts by mass with respect to 100 parts by mass of the crosslinkable fluororubber A, respectively. The sheet-shaped rubber compositions produced in the same manner as in Example 3 were referred to as Examples 10 to 13.

<Comparative Example 1>
A sheet-shaped rubber composition produced by the same operation as in Example 1 was used as Comparative Example 1 except that the ionic liquid A was not added.

<Comparative Examples 2 to 9>
Instead of the ionic liquid A, 5.0 parts by mass of a polymer type antistatic agent A (Perestat HC250 manufactured by Sanyo Chemical Industry Co., Ltd.) and 100% by weight of a crosslinkable fluororubber A, and a polymer type antistatic agent B (Perectron) were used. 5.0 parts by mass of PVL Sanyo Kasei Co., Ltd., 10 parts by mass of polymer type antistatic agent C (manufactured by Pebax MV1074SP01 Arkema), 10 parts by mass of polymer type antistatic agent D (manufactured by Pebax MH2030 Arkema), high 15 parts by mass of a molecular type antistatic agent E (manufactured by Mitsui DuPont Polychemical Co., Ltd. SD100), 15 parts by mass of antistatic agent F (manufactured by Mitsui Dupont Mitsui Polychemical Co., Ltd. MK400), and a charge containing Li salt A sheet-shaped rubber produced in the same manner as in Example 1 except that 10 parts by mass of an anti-static agent (Sanconol TBX-8310 manufactured by Sanko Chemical Industry Co., Ltd.) and 5.0 parts by mass of an antistatic agent containing a Li salt were used. The compositions were Comparative Examples 2-9.

<Examples 14 and 15>
A ternary FKM (Daiel G-912 manufactured by Daikin Industries, Ltd.) for peroxide crosslinking of the crosslinkable fluororubber B was added to 5.0 parts by mass of the ionic liquid A and 100 parts by mass of the crosslinkable fluororubber B, and An uncrosslinked rubber composition was prepared by mixing 1.5 parts by weight of peroxide, 4.0 parts by weight of a crosslinking aid, and 10 parts by weight of powdery inorganic filler hydrophobic silica (Aerosil R972 manufactured by Evonik). A sheet-shaped rubber composition produced in the same manner as in Example 1 except that it was used was set as Example 14. Further, a sheet-shaped rubber composition produced by the same operation as in Example 14 was used as Example 15 except that the ionic liquid C was used instead of the ionic liquid A.

<Comparative Example 11>
A sheet-shaped rubber composition produced in the same manner as in Example 14 except that the ionic liquid A was not mixed was set as Comparative Example 11.

(Test/evaluation method)
<Surface resistivity and volume resistivity>
The volume resistivities of the rubber compositions of Examples 1 to 15 and Comparative Examples 1 to 11 were measured based on JISK6271:2008. Then, the volume resistivity, 1.0 × ^{10 12} Ω · cm or less of those of ^{AA, 1.0 × 10 12 Ω ·} cm and beyond 1.0 × ^{10 13} Ω · cm or less those of A, A sample having a resistance of more than 1.0×10 ¹³ Ω·cm was evaluated as B.

<Charging test>
For each of the rubber compositions of Examples 1 to 8 and 10 to 15 and Comparative Examples 1 to 2, 4, 8 to 9, and 11, according to the method A (half-life measurement method) defined in JIS L1094:2014. A charge test was performed to measure the half-life. The half-life was evaluated as AA when it was 1.0 second or shorter, A when it was more than 1.0 second and not more than 2.0 seconds, and B when it was more than 2.0 seconds.

<Compression set>
For each of Examples 1 to 13 and Comparative Examples 1 to 5 and 8 to 9, compression set was measured based on JISK6262:2013 at a test time of 72 hours and a test temperature of 150°C. The compression set was rated as A for 30.0% or less and B for more than 30.0%.

(Test results)
The test results are shown in Tables 1 to 4. From these results, it is understood that by blending the ionic liquid with the crosslinkable fluororubber, it is possible to prevent the static charge without impairing the compression set without using a powdery or granular antistatic agent. In addition, excellent distinguishability can be obtained.

INDUSTRIAL APPLICABILITY The present invention is useful in the technical field of a rubber material for a sealing material and a sealing material using the same.

Claims (2)

A rubber material for a sealing material, which contains an uncrosslinked crosslinkable fluororubber, an ionic liquid, and a crosslinking agent, and does not contain carbon black. A sealing material formed of a rubber composition obtained by crosslinking the crosslinkable fluororubber of the rubber material for a sealing material according to claim 1.