Fluoropolymer elastomer and preparation method thereof

Abstract

The invention provides a fluoropolymer elastomer and a preparation method thereof. The fluoropolymer elastomer is prepared from a fluorine-containing monomer component, an emulsifier, a cross-linking agent, an initiator and water, the cross-linking agent comprises a halogen-free cross-linking agent. According to the fluoropolymer elastomer provided by the invention, due to the introduction of the halogen-free cross-linking agent, a branched chain containing olefin is formed on the main chain, the distance between the main chains is increased, and meanwhile, the branched chain can be used as a common terminal group to effectively control the molecular structure of the fluoropolymer in the polymerization process; the elastic structure of the fluoropolymer elastomer is more stable, the later vulcanization time is shortened, the demolding performance is more excellent, and product processing in molding modes of mold pressing, injection and the like is facilitated. Therefore, the fluoropolymer elastomer provided by the invention has relatively low compression set, low temperature resistance and excellent processability.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer elastomers, and in particular to a fluoropolymer elastomer and a preparation method thereof. Background Art

[0002] At present, there are many fluoropolymer elastomers on the market, including bisphenol-cured fluoropolymer elastomers, peroxide-cured fluoropolymer elastomers and polyamine-cured fluoropolymer elastomers. Among them, peroxide-cured fluoropolymer elastomers have a higher fluorine content. Compared with other vulcanization systems, they have higher resistance to high-temperature water vapor, chemical media resistance and low fuel permeation.

[0003] Seals and media-resistant composite pipes made from peroxide-cured fluoropolymer elastomers are widely used in the automotive, semiconductor, electronic terminal, new energy, machinery, petrochemical, and other fields. However, the high compression set, poor low-temperature resistance, and processability of peroxide-cured fluoropolymer elastomers limit the application of high-fluorine-content products.

[0004] In order to obtain a fluoropolymer elastomer O-ring or fuel pipe with better performance, it is of great significance to provide a fluoropolymer elastomer with a stable structure. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a fluoropolymer elastomer with low compression permanent deformation and excellent processing performance, thereby solving the problem of deterioration of sealing performance and permeation resistance of the fluoropolymer elastomer in harsh media environments.

[0006] In view of this, the present application provides a fluoropolymer elastomer prepared from a fluorine-containing monomer component, a crosslinking agent, an emulsifier, an initiator and water; the crosslinking agent includes a non-halogen crosslinking agent.

[0007] Preferably, the crosslinking agent is selected from a mixture of a non-halogen crosslinking agent and a halogen-containing crosslinking agent.

[0008] Preferably, the non-halogen crosslinking agent contains olefin groups for crosslinking, and the number of the olefin groups is ≥2.

[0009] Preferably, the non-halogen crosslinking agent is selected from at least one of 1,3-butadiene, 1,4-pentadiene, 1,5-hexadiene, 2-methyl-1,3-pentadiene, 2,6-dimethyl-2,5-diheptene, 2,4,6-trimethyl-1,3,6-triheptene, 2,6-dimethyl-1,3,5,7-octatetraene, cyclopentadiene, cyclohexadiene, 2,5-norbornadiene, cycloheptatriene, 1,5,9-cyclododecatriene, divinylbenzene, trivinylbenzene, triallyl cyanurate and triallyl isocyanurate;

[0010] The halogen-containing crosslinking agent is selected from perfluorinated compounds containing two or more iodine atoms or bromine atoms, specifically selected from at least one of diiododifluoromethane, 1,3-diiodohexafluoropropane, 1,4-diiodooctafluorobutane and dibromoperfluorohexane.

[0011] Preferably, the fluorine-containing monomer component is selected from two or three of tetrafluoroethylene, vinylidene fluoride and hexafluoropropylene;

[0012] The emulsifier is selected from C4F9O(CF2) x (OC2F4) y (OC3F6) z At least one of perfluoropolyether carboxylate ammonium with an OCOOH structure, perfluorooctanoate with a perfluorooctanoic acid structure, and fatty alcohol ether or fatty acid ester with a polyoxyethylene structure, x is 0 to 5, y is 0 to 5, and z is 0 to 5;

[0013] The initiator is selected from at least one of persulfate, persulfate-bisulfite and diisopropyl peroxydicarbonate.

[0014] Preferably, based on the fluorine-containing monomer component, the crosslinking agent is 0.1 to 2 wt% of the fluorine-containing monomer component, the emulsifier is 0.05 to 1 wt% of the fluorine-containing monomer component, the initiator is 0.01 to 0.1 wt% of the fluorine-containing monomer component, and the mass ratio of water to the fluorine-containing monomer component is 2:1 to 5:1.

[0015] Preferably, the raw materials for preparing the fluoropolymer elastomer may further include functional monomers and low-temperature resistant modifiers;

[0016] The functional monomer is selected from at least one of hydroxyethyl acrylate, hydroxybutyl acrylate, ethyl methacrylate, hydroxybutyl methacrylate, dihydroxyphenol methacrylate, polyethylene glycol acrylate, amino (meth) acrylate and amino polyethylene glycol acrylate;

[0017] The low-temperature resistant modifier is selected from at least one of two or more isocyanate structures, specifically selected from at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and lysine diisocyanate;

[0018] The molar ratio of the functional monomer to the low-temperature resistant modifier is 1:(0.5-10), and the total added amount of the functional monomer and the low-temperature resistant modifier is 0-1 wt % of the fluorine-containing monomer component.

[0019] The present application also provides a method for preparing the fluoropolymer elastomer, comprising the following steps:

[0020] The water and emulsifier solution are mixed and heated, and then the fluorinated monomer component is added, and after mixing, an initiator is added to carry out polymerization reaction;

[0021] During the polymerization reaction, a cross-linking agent is added and an initiator and a fluorine-containing monomer component are added to obtain a fluorine polymer elastomer after the reaction.

[0022] Preferably, the raw materials for the polymerization reaction further include functional monomers, which are added simultaneously with the fluorine-containing monomer component; the raw materials for the polymerization reaction further include a low-temperature resistant modifier, which is added together with the additional initiator and fluorine-containing monomer component.

[0023] Preferably, the heating temperature is 80-100°C; the polymerization reaction pressure is 1.2-2.0 MPa, and the temperature is 80-100°C.

[0024] The present application provides a fluoropolymer elastomer prepared from a fluorine-containing monomer component, a crosslinking agent, an emulsifier, an initiator, and water; the crosslinking agent includes a non-halogen crosslinking agent. Due to the introduction of the non-halogen crosslinking agent, the fluoropolymer elastomer provided by the present application forms olefin-containing side chains on its main chain, increasing the distance between the main chains. At the same time, the non-halogen crosslinking agent can effectively control the molecular structure of the fluoropolymer during the polymerization process as a common terminal group, making the elastic structure of the fluoropolymer elastomer more stable, shortening the vulcanization time in the later stage, and improving the demolding performance, making it easier to process products using molding methods such as molding and injection molding. Therefore, the fluoropolymer elastomer has low compression set, low-temperature resistance, and excellent processing performance.

[0025] Furthermore, the fluoropolymer elastomer provided by the present invention also includes functional monomers and low-temperature resistant modifiers, which, when grafted in the later stage of polymerization, will make the formed fluoropolymer elastomer have better low-temperature resistance. DETAILED DESCRIPTION

[0026] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0027] To achieve a more stable fluoropolymer elastomer structure, the present invention provides a fluoropolymer elastomer that incorporates a non-halogen crosslinker containing olefin groups and a crosslinking polymerization method using polyene groups, resulting in a fluoropolymer elastomer with a stable network structure. This addresses the issues inherent in peroxide vulcanization systems. Specifically, embodiments of the present invention disclose a fluoropolymer elastomer prepared from a fluorine-containing monomer component, a crosslinker, an emulsifier, an initiator, and water; the crosslinker includes a non-halogen crosslinker.

[0028] In the fluoropolymer elastomer provided in the present application, the crosslinking agent is specifically a mixture of a non-halogen crosslinking agent containing olefin groups and a halogen-containing crosslinking agent; the non-halogen crosslinking agent in the present application means that the crosslinking agent does not include halogen elements but includes olefin groups. The number of olefin groups in the non-halogen crosslinking agent is ≥2, that is, the non-halogen crosslinking agent described in the present application is a multi-olefin crosslinking agent, which can be a linear structure, a branched structure, or a cyclic structure; specifically, the non-halogen crosslinking agent is selected from at least one of 1,3-butadiene, 1,4-pentadiene, 1,5-hexadiene, 2-methyl-1,3-pentadiene, 2,6-dimethyl-2,5-diheptene, 2,4,6-trimethyl-1,3,6-triheptene, 2,6-dimethyl-1,3,5,7-octatetraene, cyclopentadiene, cyclohexadiene, 2,5-norbornadiene, cycloheptatriene, 1,5,9-cyclododecatriene, divinylbenzene, trivinylbenzene, triallyl cyanurate and triallyl isocyanurate; more specifically, the non-halogen crosslinking agent is selected from divinylbenzene or triallyl cyanurate. The non-halogen crosslinking agent has multiple olefin groups, which can effectively control the molecular structure of the fluoropolymer during the polymerization process to obtain a fluoropolymer with a stable elastic structure; if there is only one olefin group, it will copolymerize with the fluorine monomer during polymerization, and cannot form a vulcanization point after polymerization, thereby reducing the performance of the fluoropolymer elastomer. The halogen-containing crosslinking agent is a halogen-containing crosslinking agent well known to those skilled in the art; specifically, the halogen-containing crosslinking agent is selected from perfluorinated compounds containing two or more iodine atoms or bromine atoms, more specifically selected from at least one of diiododifluoromethane, 1,3-diiodohexafluoropropane, 1,4-diiodooctafluorobutane and dibromoperfluorohexane. The emulsifier is specifically selected from C4F9O(CF2) x (OC2F4) y (OC3F6) z At least one of ammonium perfluoropolyether carboxylate with an OCOOH structure, perfluorooctanoate with a perfluorooctanoic acid structure, and fatty alcohol ether or fatty acid ester with a polyoxyethylene structure, wherein x is 0 to 5, y is 0 to 5, and z is 0 to 5; specifically, the emulsifier is selected from ammonium perfluorooctanoate. The initiator is selected from at least one of organic peroxides such as persulfate, persulfate-bisulfite, and diisopropyl peroxydicarbonate; specifically, the initiator is selected from ammonium persulfate.

[0029] In the present application, the fluorinated monomer components are at least two, specifically selected from two or three of tetrafluoroethylene, vinylidene fluoride, and hexafluoropropylene. When vinylidene fluoride and hexafluoropropylene are selected as the fluorinated monomers, the flexibility and fluorine content of the fluoropolymer elastomer can be balanced to meet the elasticity requirements. The selection of tetrafluoroethylene can increase the fluorine content, thereby enhancing the chemical resistance and high temperature resistance of the fluorinated monomer. In a specific embodiment, the fluorinated monomer components are selected from tetrafluoroethylene, vinylidene fluoride, and hexafluoropropylene. In the present application, based on the fluorine-containing monomer component, the emulsifier is 0.05-1wt% of the fluorine-containing monomer component, the initiator is 0.01-0.1wt% of the fluorine-containing monomer component, and the cross-linker is 0.1-2wt% of the fluorine-containing monomer component; the mass ratio of water to the fluorine-containing monomer component is 2-5:1; more specifically, the emulsifier is 0.1-0.7wt% of the fluorine-containing monomer component, the initiator is 0.02-0.08wt% of the fluorine-containing monomer component, and the cross-linker is 0.2-0.8wt% of the fluorine-containing monomer component; the mass ratio of water to the fluorine-containing monomer component is 2.5-4:1.

[0030] In this application, the fluoropolymer elastomer provided by the present invention may further include a functional monomer and a low-temperature resistance modifier. Grafting the functional monomer and the low-temperature resistance modifier in the later stages of polymerization can enhance the low-temperature resistance of the resulting product. In this application, the functional monomer is selected from at least one of hydroxyl groups or amino acrylates such as hydroxyethyl acrylate, hydroxybutyl acrylate, ethyl methacrylate, hydroxybutyl methacrylate, dihydroxyphenol methacrylate, polyethylene glycol acrylate, amino (meth)acrylate, and amino polyethylene glycol acrylate. More specifically, the functional monomer is selected from hydroxybutyl acrylate. The low-temperature resistant modifier has a general structural formula of O=C=NRN=C=O or O=C=NR(-N=C=O)-N=C=O, and is specifically selected from at least one of isocyanates containing two or more isocyanate structures, such as toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, and lysine diisocyanate; more specifically, the low-temperature resistant modifier is selected from hexamethylene diisocyanate. The molar ratio of the functional monomer to the low-temperature resistant modifier is 1:(0.5-10), specifically, the molar ratio of the functional monomer to the low-temperature resistant modifier is 1:1, and the total addition amount of the functional monomer and the low-temperature resistant modifier is 0-1wt% of the fluorine-containing monomer component.

[0031] Furthermore, the present application also provides a method for preparing a fluoropolymer elastomer, comprising the following steps:

[0032] The water and emulsifier solution are mixed and heated, and then the fluorinated monomer component is added, and after mixing, an initiator is added to carry out polymerization reaction;

[0033] During the polymerization reaction, a cross-linking agent is added and an initiator and a fluorine-containing monomer component are added to obtain a fluorine polymer elastomer after the reaction.

[0034] In the preparation process of the fluoropolymer elastomer, the present application first mixes water and an emulsifier solution and heats it to 80-100°C. Then, the fluorinated monomer component is added. After mixing, an initiator is added to initiate a polymerization reaction. During the above raw material addition and polymerization process, it is necessary to ensure that there is no oxygen, and the reaction can be carried out in a nitrogen atmosphere. After the addition of the fluorinated monomer component, the functional monomer can be added. During the polymerization process, the initiator, crosslinking agent, and fluorinated monomer component are added multiple times, and a low-temperature modifier can also be added.

[0035] The above-mentioned method of adding raw materials can make the raw materials dispersed evenly, react thoroughly, and increase the reaction rate; at the same time, the cross-linking agent is added during the polymerization reaction to facilitate the formation of vulcanization point functional groups.

[0036] In order to further understand the present invention, the fluoropolymer elastomer and the preparation method thereof provided by the present invention are described in detail below with reference to the examples. The protection scope of the present invention is not limited by the following examples.

[0037] Example

[0038] A method for preparing a low compression set and low-temperature resistant fluoropolymer elastomer comprises the following polymerization methods:

[0039] 1) Repeatedly use nitrogen N2 to replace the gas in the polymerization reaction vessel to fully expel the oxygen therein; inject a certain amount of deionized water and emulsifier solution into the polymerization reaction vessel from which oxygen has been removed;

[0040] 2) replacing the oxygen in the polymerization reaction vessel with N2 again and heating the temperature in the polymerization reaction vessel to 80°C;

[0041] 3) injecting a certain proportion of a fluorinated mixed monomer of vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, and hydroxybutyl acrylate into the polymerization reaction vessel obtained in 2) until the pressure in the polymerization reaction vessel reaches 1.2 to 1.3 MPa; during the stirring process, adjusting the temperature of the polymerization reaction vessel so that the mixture in the polymerization reaction vessel reaches 80° C., and adding an initiator to start the polymerization reaction;

[0042] 4) During the polymerization process, the initiator is replenished several times, and a certain amount of cross-linking agent is added; a certain proportion of the above-mentioned fluorine-containing mixed monomer is replenished, and a certain amount of hexamethylene diisocyanate is added. The pressure of the polymerization reaction vessel during the polymerization process is maintained at 1.2-1.3 MPa and the temperature is 80° C.;

[0043] After the polymerization is completed, the polymer obtained is subjected to post-treatment processes such as coagulation and drying to obtain a fluoropolymer elastomer with low compression permanent deformation and low temperature resistance.

[0044] Preparation of fluoropolymer elastomers The fluoropolymer elastomers were prepared according to the above method. The proportions of the raw materials and the properties of the fluoropolymer elastomers are shown in Table 1.

[0045] Table 1 Composition and performance data of fluoropolymer elastomers

[0046]

[0047] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0048] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fluoropolymer elastomer prepared from a fluorine-containing monomer component, a crosslinking agent, an emulsifier, an initiator and water; the crosslinking agent comprises a non-halogen crosslinking agent.

2. The fluoropolymer elastomer according to claim 1, wherein The crosslinking agent is selected from a mixture of a non-halogen crosslinking agent and a halogen-containing crosslinking agent.

3. The fluoropolymer elastomer according to claim 1 or 2, characterized in that The non-halogen cross-linking agent contains an olefin group for cross-linking, and the number of the olefin group is ≥2.

4. The fluoropolymer elastomer according to claim 1 or 2, characterized in that The non-halogen crosslinking agent is selected from at least one of 1,3-butadiene, 1,4-pentadiene, 1,5-hexadiene, 2-methyl-1,3-pentadiene, 2,6-dimethyl-2,5-diheptene, 2,4,6-trimethyl-1,3,6-triheptene, 2,6-dimethyl-1,3,5,7-octatetraene, cyclopentadiene, cyclohexadiene, 2,5-norbornadiene, cycloheptatriene, 1,5,9-cyclododecatriene, divinylbenzene, trivinylbenzene, triallyl cyanurate and triallyl isocyanurate; The halogen-containing crosslinking agent is selected from perfluorinated compounds containing two or more iodine atoms or bromine atoms, specifically selected from at least one of diiododifluoromethane, 1,3-diiodohexafluoropropane, 1,4-diiodooctafluorobutane and dibromoperfluorohexane.

5. The fluoropolymer elastomer according to claim 1 or 2, characterized in that The fluorine-containing monomer component is selected from two or three of tetrafluoroethylene, vinylidene fluoride and hexafluoropropylene; The emulsifier is selected from C4F9O(CF2) x (OC2F4) y (OC3F6) z At least one of perfluoropolyether carboxylate ammonium with an OCOOH structure, perfluorooctanoate with a perfluorooctanoic acid structure, and fatty alcohol ether or fatty acid ester with a polyoxyethylene structure, x is 0 to 5, y is 0 to 5, and z is 0 to 5; The initiator is selected from at least one of persulfate, persulfate-bisulfite and diisopropyl peroxydicarbonate.

6. The fluoropolymer elastomer according to claim 1, wherein Based on the fluorine-containing monomer component, the crosslinking agent is 0.1 to 2 wt% of the fluorine-containing monomer component, the emulsifier is 0.05 to 1 wt% of the fluorine-containing monomer component, the initiator is 0.01 to 0.1 wt% of the fluorine-containing monomer component, and the mass ratio of water to the fluorine-containing monomer component is 2:1 to 5:

1.

7. The fluoropolymer elastomer according to claim 1, wherein The raw materials for preparing the fluoropolymer elastomer may also include functional monomers and low-temperature resistant modifiers; The functional monomer is selected from at least one of hydroxyethyl acrylate, hydroxybutyl acrylate, ethyl methacrylate, hydroxybutyl methacrylate, dihydroxyphenol methacrylate, polyethylene glycol acrylate, amino (meth) acrylate and amino polyethylene glycol acrylate; The low-temperature resistant modifier is selected from at least one of two or more isocyanate structures, specifically selected from at least one of toluene diisocyanate, isophorone diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate and lysine diisocyanate; The molar ratio of the functional monomer to the low-temperature resistant modifier is 1:(0.5-10), and the total added amount of the functional monomer and the low-temperature resistant modifier is 0-1 wt % of the fluorine-containing monomer component.

8. The method for preparing the fluoropolymer elastomer according to claim 1, comprising the steps of: The water and emulsifier solution are mixed and heated, and then the fluorinated monomer component is added, and after mixing, an initiator is added to carry out polymerization reaction; During the polymerization reaction, a cross-linking agent is added and an initiator and a fluorine-containing monomer component are added to obtain a fluorine polymer elastomer after the reaction.

9. The preparation method according to claim 8, characterized in that The raw materials for the polymerization reaction also include functional monomers, which are added simultaneously with the fluorine-containing monomer component; the raw materials for the polymerization reaction also include a low-temperature resistant modifier, which is added together with the supplementary initiator and the fluorine-containing monomer component.

10. The preparation method according to claim 8 or 9, characterized in that: The heating temperature is 80-100° C.; the polymerization reaction pressure is 1.2-2.0 MPa, and the temperature is 80-100° C.

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