JP3305400B2 - Method for producing fluoropolymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently producing a fluorine-based polymer having good heat resistance, solvent resistance, chemical resistance and the like by using a polymerization medium which hardly causes environmental destruction.

[0002]

2. Description of the Related Art In recent years, a fluorine-based polymer is a polymer material having excellent heat resistance, solvent resistance, chemical resistance, and the like.
Utilizing its features, it is used for various purposes.

[0003] As a method for producing a fluorine-based polymer, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method are known. As a polymerization medium for the solution polymerization method and the suspension polymerization method, chlorofluorocarbon or the like is used. An active solvent is generally used from the viewpoint of providing a high molecular weight copolymer and the polymerization rate. Specific examples of the chlorofluorocarbon include trichlorofluoromethane, dichlorodifluoromethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, and the like. Trichlorotrifluoroethane is mainly used from the viewpoint of handling.

In recent years, the ozone layer depletion has been taken up internationally as a global environmental destruction problem, and chlorofluorocarbon has been pointed out as a causative substance thereof, and the world is heading toward total elimination. For this reason, it has become necessary to stop using the chlorofluorocarbon used in producing the fluoropolymer.

As a substitute for the chlorofluorocarbon, a perfluorocarbon or a hydrofluorocarbon containing a hydrogen atom has been proposed because of its small ozone depletion potential. When these substitutes are used as a polymerization medium, a commonly used chain transfer agent such as methanol may hardly be compatible with the polymerization medium,
In this case, it cannot be used as a chain transfer agent .

[0006]

SUMMARY OF THE INVENTION Under these circumstances, the present invention provides a fluorine-based polymer having excellent heat resistance, solvent resistance, and chemical resistance when a perfluorocarbon or hydrofluorocarbon is used as a polymerization medium. It is intended to provide a chain transfer agent for efficiently producing a.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object and found that CF ₂ ClC
It has been found that the purpose can be achieved by using F ₂ CHClF and / or CF ₃ CF ₂ CHCl ₂ as a chain transfer agent for polymerization.

That is, the present invention relates to a perfluorocarbon
Polymer containing a fluoroolefin unit as a main constituent unit by polymerization in a polymerization medium comprising olefin and / or hydrofluorocarbon (however, a fluoropolymer comprising vinylidene fluoride and hexafluoropropylene). Excluding a ternary fluorine-containing elastomer and a ternary fluorine-containing elastomer composed of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene), CF ₂ ClCF ₂ CHClF and / or CF ₃ CF ₂
This is a method for producing a fluorine-based polymer, characterized by using CHCl ₂ .

In the present invention, the fluoropolymer containing a fluoroolefin unit as a main constituent unit can be obtained by polymerizing a fluoroolefin monomer alone or by preparing a fluoroolefin monomer.
It is produced by copolymerizing two or more kinds of olefin monomers or copolymerizing the following other monomers other than the fluoroolefin monomer copolymerized with the fluoroolefin monomer.
You.

[0010] The present invention fluoroolefin monomer used in is an olefin having at least one fluorine atom in the molecule, preferably, from the viewpoint of the nature of the polymerisable and resulting polymer, 2 or 3 carbon atoms Is a fluoroolefin monomer.

Specific examples of such a fluoroolefin monomer include tetrafluoroethylene ( TFE ) , C
F ₂ = CFCl, fluoro ethylene monomer such as CF ₂ = CH _2, hexafluoropropylene (HFP), CF
Fluoro propylene monomer such as ₂ = CHCF _3. These fluoroolefin monomers may be used alone or in combination of two or more.

Further, as the other monomer of said, C
F ₃ CF ₂ CF ₂ CF ₂ CH = CH ₂ or CF ₃ CF ₂ CF ₂ CF
(Perfluoroalkyl) ethylene-based monomer having 4 to 12 carbon atoms in a perfluoroalkyl group such as ₂ CF = CH _{2
^{Body, R f (OCFXCF 2) m}} OCF = CF 2 ( formula in ^the R ^f perfluoroalkyl group having 1 to 6 carbon atoms, X is a fluorine atom or a trifluoromethyl group, m represents an integer of 1-6. Perfluorovinyl ether monomers such as
_{H 3 OC (= O) CF} 2 CF 2 CF 2 OCF = CF 2 and FS
A perfluorovinyl ether monomer having a group which can be easily converted into a carboxylic acid group or a sulfonic acid group, such as O ₂ CF ₂ CF ₂ OCF (CF ₃ ) CF ₂ OCF ＯCF _2, is used.
Is Ru. Further, olefin monomers such as ethylene, propylene, and isobutylene are also used. 2 more types
They may be used in combination . Preferred Fluorine System of the Invention
As the polymer, TFE / ethylene copolymer, TFE
/ Perfluoro (alkyl vinyl ether) copolymer
Alternatively, a TFE / HFP copolymer may be used.

[0013] In the present invention, as the polymerization medium, less perfluorocarbon and / or hydrofluorocarbon of bringing environmental destruction is used. As perfluorocarbon, perfluoropentane,
Examples include perfluorohexane, perfluoroheptane, perfluorooctane, perfluorocyclohexane, and the like, and mixtures thereof. The hydrofluorocarbons include (1) CF ₃ (CF ₂ ) _n CH ₂ C
H ₃ , (2) CF ₃ (CF ₂ ) _n H, (3) H (CF ₂ )
_n H, (4) CF ₃ CF ₂ CHFCHFCF ₃ , (5) CH
Examples thereof include F ₂ CF ₂ CF ₂ CHF ₂ , (6) alkanes obtained by hydrogenation or hydrogen fluoride addition of oligomers of TFE and / or HFP, and mixtures thereof. However, in the above, n shows the integer of 1-8.

In the present invention, a perfluorocarbon or a hydrofluorocarbon may be used as a polymerization medium containing an inert solvent such as water. The amount of the polymerization medium, but it is capable of changing the type of the monomers to be polymerized, with respect to mass of the monomer total amount, 3-100 times, is preferably 5 to 50 times . The amount of the chain transfer agent may vary depending on the molecular weight of the obtained that fluorine-based polymer is 0.01 to 20 on the quality of the entire polymerization medium
0 mass%, preferably 0.05 to 100 mass%.

The chain transfer agent CF ₂ ClCF _{2 according to the} present invention
CHClF and CF ₃ CF ₂ CHCl ₂ may be used alone or in combination. When mixed, CF ₂ ClCF ₂ CHClF and CF ₃ CF ₂
The mixing ratio of the CHCl ₂ can be selected from a wide range, the former is 0.01 to 99.99 mass%, the latter 99.99
0.01 mass%, preferably former 0.1-99.9 quality <br/> weight%, the latter is 99.9 to 0.1 mass%. Heat from stability point is preferably used in CF ₂ ClCF the ₂ CHClF alone or in which a mixture comprising 50 mass% or more. The TFE / The perfluoro (alkyl vinyl ether) copolymer and TFE / HFP copolymer chain transfer agent perfluorinated polymers such as body, CF ₃ CF ₂ C
The HCl ₂ alone or which preferably used in mixing <br/> compound containing more than 50 wt%.

In the present invention, any of a solution polymerization method and a suspension polymerization method can be adopted as a polymerization method.
The polymerization initiator to be used can be appropriately selected from those conventionally used depending on the polymerization mode. For example, bis (chloro-fluoro-acyl) Paoki shea, bis (perfluoroacyl) Paoki shea, bis (.omega. hydroperoxide perfluoroacyl) Paoki shea de, t- butyl peroxy isobutyrate, diisopropyl peroxydicarbonate, etc. And azo compounds such as azobisisobutyronitrile. The amount of the polymerization initiator, the type, depending on the polymerization reaction conditions may be appropriately changed, usually with respect to the total monomers to be polymerized, 0.005 mass%, in particular 0. 05 to 0.5 mass <br/>% about the Ru is employed.

In the polymerization reaction of the present invention, a wide range of reaction conditions can be employed without any particular limitation. For example, the optimum value of the polymerization reaction temperature can be selected depending on the type of the polymerization initiator and the like.
About 0 to 90 ° C. can be adopted. Further, the reaction pressure can be appropriately selected, but it is usually preferable to employ ² to 100 kg / cm ² , especially 5 to 20 kg / cm ² .
In the present invention, the polymerization can be advantageously carried out without requiring an excessive reaction pressure. However, it is possible to employ a higher pressure and also possible to use a reduced pressure condition. Further, the present invention can be carried out by a suitable operation such as a batch system or a continuous system.

[0018]

EXAMPLES Example 1 A stainless steel reaction vessel having an inner volume of 1.2 liters was degassed, and 1000 g of perfluorohexane and 410 g of C were removed.
F ₂ ClCF ₂ CHClF, 1.8 g of (perfluorobutyl) ethylene, 85 g of TFE, and 5.9 g of ethylene were charged. And maintaining the temperature at 50 ° C., bis (perfluoro-butyryl) 1 mass <br/>% perfluorohexane solution of Paoki Passes were charged as a polymerization initiator, to initiate the reaction. During the reaction, a mixed gas of TFE and ethylene (molar ratio TFE / ethylene = 53/47) was introduced into the system, and the reaction pressure was maintained at 8.1 kg / cm ² . The polymerization initiator was intermittently charged so that the polymerization rate was almost constant, and a total of 23
ml . After 3 hours, 72 g of a white copolymer was obtained in a slurry state. Further, granulation could be performed to an average particle size of about 1 mm using water as a medium. The copolymer has a melting point of 272 ° C.
The starting point of thermal decomposition was 358 ° C, and a good compression molded product without coloring was obtained at a molding temperature of 300 ° C. The molded article had a tensile strength of 470 kg / cm ² and a tensile elongation of 420%.

Example 2 The same stainless steel reactor as in Example 1 was degassed and
0 g perfluorohexane, 420 g CF ₃ CF ₂ C
HCl ₂ , 32 g perfluoro ( propyl vinyl ether ) , 80 g TFE were charged. And maintaining the temperature at 50 ° C., charged with 1 wt% perfluorohexane solution of bis (perfluoro-butyryl) Paoki shea de as a polymerization initiator, to initiate the reaction. During the reaction, TFE was introduced into the system, and the reaction pressure was maintained at 5.1 kg / cm ² . The polymerization initiator was charged intermittently so that the polymerization rate became almost constant, and a total of 7 ml was charged. After 3.4 hours, 64 g of a white copolymer was obtained in a slurry state. Further, granulation could be performed to an average particle size of about 1 mm using water as a medium. The copolymer had a melting point of 306 ° C and a thermal decomposition onset of 480 ° C,
Good compression molded articles were obtained at a molding temperature of 0 ° C. The molded product has a tensile strength of 390 kg / cm ² and a tensile elongation of 3
70%.

Example 3 Polymerization was carried out in the same manner as in Example 2 except that 400 g of HFP was charged instead of 32 g of perfluoro ( propyl vinyl ether ) , and the charged amount of CF ₃ CF ₂ CHCl ₂ was changed to 50 g instead of 420 g. And 65 g after 3.5 hours
Was obtained as a slurry. The copolymer had a melting point of 275 ° C., a pyrolysis starting point of 450 ° C.
A good compression molded article was obtained at a molding temperature of 40 ° C. Also,
Using water as a medium, granulation was achieved to an average particle size of about 1 mm. The molded product had a tensile strength of 340 kg / cm ² and a tensile elongation of 350%.

Comparative Example 1 The same stainless steel reaction vessel as in Example 1 was degassed, and
0 g perfluorohexane, 50 g methanol,
1.8 g of (perfluorobutyl) ethylene, 85 g of TFE and 5.9 g of ethylene were charged. 50 ℃
Held in charged with 1 wt% perfluorohexane solution of bis (perfluoro-butyryl) Paoki shea de as a polymerization initiator, to initiate the reaction. During the reaction, TFE
Mixed gas of ethylene and ethylene (molar ratio TFE / ethylene = 53
/ 47) and the reaction pressure was maintained at 8.5 kg / cm ² . The polymerization initiator was charged intermittently so that the polymerization rate was almost constant, and a total of 23 ml was charged. After 2 hours, 75 g of a white copolymer was obtained in a slurry state.
Tsu name to the powder in water tried to granulation as a medium, but can not be granulated
Was . The copolymer has a melting point of 272 ° C. and a thermal decomposition starting point of 350 ° C.
Was . The resulting polymer has a high melt viscosity, 300 ° C
Did not produce a uniform molded article.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that 410 g of CH ₃ CCl ₂ F was charged instead of CF ₂ ClCF ₂ CHClF. 75 g of polymer were obtained. This polymer is
Was compression molded at 0 ℃, colored brown.

[0023]

According to the present invention, by using the less preferred polymerization medium and compatibility good chain transfer agents resulting in environmental damage, heat resistance, solvent resistance, good fluorine such as chemical resistance A polymer can be produced efficiently. Also,
The chain transfer agent in the present invention can increase the affinity between the obtained fluorine-based polymer and the polymerization medium, and can improve the handling during the steps after the polymerization (granulation, drying, etc.).

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-136008 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 2/00-2/60 C08F 14 / 18,14 / 26

Claims (3)

(57) [Claims] (1) a perfluorocarbon and / or high
A fluoropolymer containing a fluoroolefin unit as a main constituent unit by polymerization in a polymerization medium comprising drofluorocarbon (however, a binary fluoroelastomer composed of vinylidene fluoride and hexafluoropropylene, and vinylidene fluoride and hexane) Excluding a tertiary fluorine-containing elastomer comprising fluoropropylene and tetrafluoroethylene)), CF ₂ ClCF ₂ CH is used as a chain transfer agent for the polymerization.
A method for producing a fluoropolymer, comprising using ClF and / or CF ₃ CF ₂ CHCl ₂ . 2. The fluorine-based polymer is a tetrafluoroethylene / ethylene-based copolymer, a tetrafluoroethylene / perfluoro (alkyl vinyl ether) -based copolymer, or a tetrafluoroethylene / hexafluoropropylene-based copolymer. The method according to claim 1. Wherein the polymerization medium is, Process according to claim 1 or 2 is at least one hydrofluorocarbon selected from the group consisting of the following (1) to (6). However,
n shows the integer of 1-8. (1) CF ₃ (CF ₂ ) _n CH ₂ CH ₃ , (2) CF ₃ (CF ₂ ) _n H, (3) H (CF ₂ ) _n H, (4) CF ₃ CF ₂ CHFCHFCF ₃ , (5) ) CHF ₂ CF ₂ CF ₂ CHF ₂ , (6) Alkanes obtained by hydrogenation or hydrogen fluoride addition to oligomers of tetrafluoroethylene and / or hexafluoropropylene.