Patent Application
20150094407
The present invention relates to a perfluoroelastomer composition. More particularly, the present invention relates to a perfluoroelastomer composition that provides a colored perfluoroelastomer molded product having heat resistance under high temperature conditions of 300° C. or above.
Fluorine-containing elastomers, such as fluorinated fluoroelastomers (e.g., a vinylidene fluoride [VdF]/hexafluoropropylene [HFP] copolymer and a VdF/HFP/tetrafluoroethylene [TFE] terpolymer) and perfluorinated perfluoroelastomers (e.g., a TFE/perfluoromethylvinylether [PMVE] copolymer) have excellent performance in terms of heat resistance, chemical resistance, etc., as compared to other rubbers. They are therefore widely used as molding materials for sealing materials, such as O rings, gaskets, and packing, in various industrial fields, including automobile industry.
In particular, perfluoroelastomers, which are polymers comprising perfluoromonomers, such as TFE, HFP, and PMVE, have superior heat resistance and chemical resistance, as compared to other fluorine-containing elastomers than perfluoroelastomers; however, for semiconductor applications and some other applications, perfluoroelastomers are required to be used in an environment at 300° C., but their heat resistance is not sufficient for that environment. Furthermore, there may be limitations on the use of reinforcing materials and fillers, in terms of metal or contamination.
Patent Document 1 discloses a fluororubber composition comprising:
Patent Document 2 discloses a composition comprising:
HON═C(NH2)—(CF2)n—C(NH2)═NOH
Patent Document 3 discloses a composition comprising, as a perfluoroelastomer containing a cyano group, a fluorine-containing elastomer having a copolymerization composition comprising:
Meanwhile, Patent Document 4 discloses a fluorine-containing elastomer composition comprising:
Patent Document 1: JP-A-2005-344074
Patent Document 2: JP-B-3082626
Patent Document 3: JP-A-2009-161662
Patent Document 4: JP-B-4720501
An object of the present invention is to provide a perfluoroelastomer composition providing a colored vulcanizate (a colored molded product) that does not form blooms under high temperature conditions of 300° C. or above, and that can be effectively used, for example, as a sealing material for semiconductor manufacturing devices.
The above object of the present invention can be achieved by a perfluoroelastomer composition comprising:
100 parts by weight of a perfluoroelastomer containing a cyano group as a crosslinkable group;
0.2 to 5 parts by weight of a bisamidoxime compound vulcanizing agent represented by the general formula:
HON═C(NH2)—(CF2)n—C(NH2)═NOH
wherein n is an integer of 1 to 10; and
0.005 to 0.3 parts by weight of a coloring agent with a melting point of 300° C. or above.
A perfluoroelastomer colored molded product obtained by vulcanization molding of the perfluoroelastomer composition of the present invention does not undergo discoloration or form blooms under high temperature conditions of 300° C. or above, and has excellent heat resistance. Therefore, the perfluoroelastomer colored molded product can be effectively used, for example, as a sealing material for semiconductor manufacturing devices, for plasma irradiation.
The composition of the perfluoroelastomer containing a cyano group as a crosslinkable group is not limited, as long as it can provide a vulcanizate having excellent heat resistance at a high temperature of 300° C. or above; however, the perfluoroelastomer preferably has a copolymerization composition comprising:
When the copolymerization ratio of tetrafluoroethylene as the component (A) is lower than this range, heat resistance is inferior, and adhesion to silicon, metal, silica glass, etc., increases. In contrast, when the copolymerization ratio of tetrafluoroethylene as the component (A) is greater than this range, the resulting copolymer behaves likes a resin, rather than an elastomer, thus degrading sealing performance and reducing processability.
When the copolymerization ratio of perfluoro(lower alkyl vinyl ether) or perfluoro(lower alkoxy lower alkyl vinyl ether) as the component (B) is lower than this range, the copolymerization ratio of tetrafluoroethylene is relatively higher, and the resulting copolymer becomes a resin-like state, significantly degrading sealing performance. On the other hand, when the copolymerization ratio of the component (B) is greater than this range, particularly adhesion is remarkably deteriorated.
Examples of the perfluoro(lower alkyl vinyl ether) as the component (B) comonomer typically include perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), and the like. Moreover, examples of the perfluoro(lower alkoxy lower alkyl vinyl ether) are as follows:
Among these examples, those wherein CnF2n+1is CF3 are particularly preferably used.
Furthermore, examples of the perfluoro unsaturated nitrile compound as the component (C) comonomer, which is used as a crosslinking-site monomer, are as follows:
The amount of copolymerization of the perfluoro unsaturated nitrile compound as the component (C) is 0.2 to 3.0 mol %, preferably 0.5 to 2.0 mol %, which is required as a crosslinkable group.
The copolymerization reaction using these monomers is generally carried out in the following manner: Water, a fluorine-containing emulsifier (e.g., ammonium perfluorooctanoate), and a buffer (e.g., potassium dihydrogen phosphate) are charged in a stainless steel autoclave. Thereafter, tetrafluoroethylene, perfluoro(lower alkyl vinyl ether) or perfluoro(lower alkoxy lower alkyl vinyl ether), and a perfluoro unsaturated nitrile compound are charged, and the temperature is raised to about 50 to 80° C. Then, a redox initiator composed of a radical generator (e.g., ammonium persulfate) and a reducing agent (e.g., sodium sulfite) is added. The reaction pressure is preferably maintained at about 0.75 to 0.85 MPa. Accordingly, in order to increase the pressure in the reactor that decreases with the progress of the reaction, it is preferable to perform the reaction while adding a mixture of these three monomers in batches.
The perfluoroelastomer terpolymer comprising the above components as essential components can be copolymerized with other fluorinated olefins, various vinyl compounds, etc., in an amount that does not inhibit the copolymerization reaction and that does not impair vulcanizate physical properties (about 20 mol % or less). Examples of other fluorinated olefins include vinylidene fluoride, monofluoroethylene, trifluoroethylene, trifluoropropylene, pentafluoropropylene, hexafluoropropylene, hexafluoroisobutylene, chlorotrifluoroethylene, and dichlorodifluoroethylene. Examples of vinyl compounds include ethylene, propylene, 1-butene, isobutylene, methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, and trifluorostyrene.
The perfluoroelastomer containing a cyano group is mixed with, as a vulcanizing agent, a bisamidoxime compound represented by the general formula:
HON═C(NH2)—(CF2)n—C(NH2)═NOH
n: 1 to 10,
as described in Patent Document 2, mentioned above, in an amount of 0.2 to 5 parts by weight, preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the perfluoroelastomer.
The perfluoroelastomer containing a cyano group is further mixed with a coloring agent in an amount of 0.005 to 0.3 parts by weight, preferably 0.01 to 0.2 parts by weight, based on 100 parts by weight of the perfluoroelastomer. When the amount of coloring agent used is less than this range, the coloring effect may be insufficient, depending on the type of coloring agent. In contrast, when the amount of coloring agent used is greater than this range, the coloring agent, depending on its type, may be slightly sublimated, thereby leading to vaporization of a very small amount of coloring agent even at a temperature below the melting point. Consequently, the vulcanized molded product used at 300° C. may undergo slight color fading, and undesirable contamination may occur in the oven during oven vulcanization for the production of the vulcanized molded product. Patent Document 4 discloses a fluorine-containing elastomer composition comprising, as a compound having plasma antiaging effects, at least one member selected from the group consisting of an isoindolinone pigment, a quinacridone pigment, a diketopyrrolopyrrole pigment, and an anthraquinone pigment. However, such a pigment is used in an amount of 0.5 to 20 parts by weight, based on 100 parts by weight of the fluorine-containing elastomer. Thus, the amount of pigment used in Patent Document 4 is higher than the upper limit of the amount of coloring agent specified in the present invention.
Since the coloring agent is intended to be used in an environment in which heat resistance at 300° C. or above is required (e.g., for semiconductor applications), a metal element-free organic compound that does not decompose at 300° C. is used. An organic compound having a melting point of 300° C. or above is preferably used, in terms of preventing bleed out from the vulcanized molded product or preventing vaporization. Examples of such organic compounds include quinacridone (melting point: 390° C.), coronene (melting point: 428° C.), perylenetetracarboxylic acid diimide (melting point: 310 to 320° C.), and 4,4′-diamino-1,1′-bianthracene-9,9′,10,10′-tetraone (melting point: 356° C.). In particular, coronene is preferably used.
The preparation of the perfluoroelastomer composition comprising the above essential components is performed by kneading with two-rolls, or the like, at about 30 to 60° C. The crosslinking of the composition is performed by heating at about 100 to 250° C. for about 1 to 120 minutes. When the composition is subjected to secondary vulcanization, it is performed in an inert gas atmosphere, such as nitrogen gas, at about 150 to 280° C. In that case, it is preferable to perform oven vulcanization along with a gradual temperature increase, as described in Examples below.
The following describes the present invention with reference to Examples.
A bisamidoxime compound [HON═C(NH2)—(CF2)4—C(NH2)═NOH] (0.7 parts by weight) and 0.1 parts by weight of quinacridone (melting point: 390° C.) were added to 100 parts by weight of a copolymer having a copolymerization composition comprising TFE, PMVE, and perfluoro(3-oxa-8-cyano-1-octene) [CPeVE; CF2═CFO(CF2)4CN] (74.0/24.7/1.3 mol %) [perfluoroelastomer A]. The mixture was kneaded on a two-roll mill at a temperature of 40 to 45° C. The kneaded product was subjected to press vulcanization (primary vulcanization) at 180° C. for 30 minutes, and then to oven vulcanization (secondary vulcanization) in a nitrogen gas atmosphere under the following conditions:
In Example 1, the same amount of coronene (melting point: 428° C.) was used in place of quinacridone.
In Example 1, the same amount of a copolymer having a composition comprising TFE, PMVE, and CPeVE (69.0/29.7/1.3 mol %) [perfluoroelastomer B] was used in place of the perfluoroelastomer A.
In Example 2, the amount of coronene was changed to 0.02 parts by weight.
In Example 2, the amount of coronene was changed to 0.2 parts by weight.
In Example 1, quinacridone was not used.
In Example 1, the same amount of N,N′-dimethylquinacridone (melting point: 286° C.) was used in place of quinacridone.
In Example 1, the same amount of perylene (melting point: 276° C.) was used in place of quinacridone.
In Example 1, the amount of quinacridone was changed to 0.4 parts by weight. Undesirable contamination was observed in the oven during oven vulcanization.
The vulcanized molded products obtained in the Examples and Comparative Examples above were subjected to the measurement of normal-state physical properties, the measurement of compression set, the evaluation of color transfer, the observation of product color (change), a plasma irradiation test, and an outgas test.
The following table shows the obtained results.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-088100 | Apr 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/055376 | 2/28/2013 | WO | 00 |
