JP2004168982A - Fluoropolymer and production method thereof - Google Patents

Abstract

The present invention provides a fluorine-containing polymer having excellent fuel barrier properties and excellent adhesion to non-fluorinated polymers.
A fluorine-containing polymer containing an acid anhydride residue derived from a chain transfer agent, wherein the content of the acid anhydride residue is 100 to 1000 per 1 × 10 ⁶ main chain carbon atoms. A fluorine-containing polymer,
[Selection figure] None

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluorinated polymer having a low fuel permeability coefficient, excellent fuel barrier properties, and excellent adhesion to non-fluorinated polymers.
[0002]
[Prior art]
Fluoropolymers such as polytetrafluoroethylene, tetrafluoroethylene / perfluoro (alkyl vinyl ether) copolymers, and ethylene / tetrafluoroethylene copolymers have excellent heat resistance, chemical resistance, weather resistance, gas barrier properties, etc. It has excellent characteristics and is used in various fields such as the semiconductor industry and the automobile industry.
[0003]
In recent years, the application of fluoropolymers to components such as tanks, hoses, and tubes, particularly fuel hoses used in automobile engine rooms that are exposed to harsh conditions such as high-temperature environments has been studied. The fuel hose is a piping hose for transferring gasoline-based fuel containing alcohol or aromatic compounds.
[0004]
In particular, a fuel hose comprising a multilayer laminate containing a fluoropolymer layer has been studied as satisfying various required characteristics. For the inner layer material that comes into direct contact with the fuel in the multi-layered laminate, it is essential to use a resin that has a fuel barrier property that does not easily permeate the fuel and a chemical resistance against erosive liquids such as ethanol and methanol contained in the fuel. It is. In this respect, the fluoropolymer is suitable as an inner layer material because it is excellent in heat resistance, chemical resistance and gas barrier properties. In particular, an ethylene / tetrafluoroethylene copolymer is preferable as an inner layer material of a fuel hose because it has excellent fuel barrier properties.
[0005]
On the other hand, as the outer layer material of the fuel hose, a non-fluorinated polymer having excellent mechanical properties and durability is used. Usually, polyamide resins such as polyamide 6, polyamide 11 and polyamide 12 are suitable as non-fluorine polymers because they have excellent characteristics.
[0006]
In the fuel hose composed of the multilayer laminate as described above, a technique for satisfactorily bonding the fluoropolymer layer and the non-fluorine polymer layer is important. If the adhesion between the layers is insufficient, the layers may peel off during use, and problems such as hose blockage and increased fuel permeation may occur.
[0007]
In view of this, a technique for improving the adhesion between layers in a multilayer laminate has been studied. For example, the surface of a tube obtained by extrusion molding of a fluoropolymer is treated by a method such as chemical treatment, corona discharge treatment, plasma discharge treatment, etc., to introduce various adhesive functional groups onto the tube surface. Then, after applying an adhesive as necessary, a method of extruding and molding a non-fluorinated polymer on the outside of the fluoropolymer tube is employed (for example, Patent Document 1 and Patent Document). 2). By these methods, a fuel hose having excellent adhesion between layers can be produced, but the process is complicated and the productivity of the laminate is low.
[0008]
Further, a method of bonding a non-fluorine polymer layer and a fluorine polymer layer using an adhesive layer made of a mixture of a non-fluorine polymer and a fluorine polymer has been proposed (for example, (See Patent Document 3 and Patent Document 4). Further, as a fluorine-based polymer that is adhesive to a non-fluorine-based polymer, it is derived from a fluorine-based polymer grafted with an ethylenically unsaturated compound having a functional group (see, for example, Patent Document 5) and a peroxide. A method for producing a fluoropolymer having a carbonate group (see, for example, Patent Document 6) has been proposed.
[0009]
A fluoropolymer that has a simple manufacturing process and can produce a fuel hose or a fuel tank made of a multilayer laminate by molding a fluoropolymer and a non-fluorine polymer by a simple method such as coextrusion molding. Development is required.
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 2-107371
[Patent Document 2]
JP-A-5-8353
[Patent Document 3]
JP-A-7-223300
[Patent Document 4]
JP-A-8-258212
[Patent Document 5]
Japanese National Patent Publication No. 10-503236
[Patent Document 6]
WO99 / 45044 pamphlet
[0011]
[Problems to be solved by the invention]
An object of the present invention is to provide a fluorine-containing polymer which is required to be developed under the background as described above and has excellent fuel barrier properties and excellent adhesion to non-fluorinated polymers.
[0012]
[Means for Solving the Problems]
The present invention is a fluorine-containing polymer containing an acid anhydride residue derived from a chain transfer agent, wherein the content of the acid anhydride residue is 1 × 10 main chain carbon atoms. ⁶ Provided is a fluoropolymer characterized in that the number is 100 to 1000 per unit.
[0013]
The present invention also provides a method for producing the above fluoropolymer, wherein an acid anhydride is used as a chain transfer agent, and a monomer containing a fluoroolefin is polymerized in the presence of a radical polymerization initiator and a polymerization medium.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The fluorine-containing polymer of the present invention is a fluorine-containing polymer having an acid anhydride residue derived from a chain transfer agent, and the content of the acid anhydride residue is 1 × 10 main chain carbon atoms. ⁶ 100 to 1000 per piece. Here, the acid anhydride residue refers to a substituent having an acid anhydride skeleton. That is, it refers to a substituent having a structure in which one hydrogen atom bonded to a carbon atom of an acid anhydride molecule is removed. If the content of the acid anhydride residue is too small, the adhesiveness with the non-fluorinated polymer is insufficient, and if it is too large, the capacity flow rate of the fluoropolymer increases and the moldability decreases. The content of acid anhydride residues is more preferably 200 to 800, and most preferably 250 to 600.
[0015]
The volume flow rate (hereinafter referred to as Q value) of the fluoropolymer of the present invention is 1-1000 mm. ³ / Second is preferred, 5 to 500 mm ³ / Second is more preferable, 10 to 200 mm ³ / Second is most preferred. The Q value is an index representing the melt fluidity of the fluoropolymer and is a measure of the molecular weight. A large Q value indicates a low molecular weight, and a small Q value indicates a high molecular weight. If the Q value is too small, extrusion molding becomes difficult. If the Q value is too large, the mechanical strength of the fluoropolymer decreases.
[0016]
The fluorine-containing polymer of the present invention is preferably a polymer or copolymer composed of polymerized units based on fluorine-containing olefins, or a copolymer composed of polymerized units based on fluorine-containing olefins and monomers other than fluorine-containing olefins.
[0017]
Examples of the fluorinated olefin include tetrafluoroethylene (hereinafter referred to as TFE), chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride (hereinafter referred to as VDF), vinyl fluoride, hexafluoropropylene (hereinafter referred to as HFP). ), CF ₂ = CFR ^f (Where R ^f Is a polyfluoroalkyl group having 2 to 10 carbon atoms. same as below. ) And the like. A fluorine-containing olefin may be used individually by 1 type, and may use 2 or more types together.
[0018]
Monomers other than fluorine-containing olefins include hydrocarbons such as ethylene (hereinafter referred to as E), propylene and butene, CH ₂ = CX (CF ₂ ) _n A compound represented by Y (wherein X and Y are each independently a hydrogen atom or a fluorine atom, and n is an integer of 2 to 8), CF ₂ = CFO (CF ₂ ) ₃ Perfluoro (alkyl vinyl ether) such as F, CF ₂ = CFOCH ₂ CF ₃ (Polyfluoroalkyl) trifluorovinyl ether, vinyl ethers such as methylvinyloxybutyl carbonate, vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butanoate, vinyl pivalate, vinyl benzoate, vinyl crotonate, (polyfluoro And (meth) acrylic acid esters such as (alkyl) acrylate and (polyfluoroalkyl) methacrylate. Monomers other than fluorine-containing olefins may be used alone or in combination of two or more.
[0019]
CH ₂ = CX (CF ₂ ) _n In the compound represented by Y, n = 2 to 4 are preferable, and the fluoropolymer is excellent in fuel barrier properties and stress crack resistance. As a specific example, CH ₂ = CF (CF ₂ ) ₂ F, CH ₂ = CF (CF ₂ ) ₃ F, CH ₂ = CF (CF ₂ ) ₄ F, CH ₂ = CF (CF ₂ ) ₂ H, CH ₂ = CF (CF ₂ ) ₃ H, CH ₂ = CF (CF ₂ ) ₄ H, CH ₂ = CH (CF ₂ ) ₂ F, CH ₂ = CH (CF ₂ ) ₃ F, CH ₂ = CH (CF ₂ ) ₄ F, CH ₂ = CH (CF ₂ ) ₂ H, CH ₂ = CH (CF ₂ ) ₃ H, CH ₂ = CH (CF ₂ ) ₄ H etc. are mentioned. CH ₂ = CF (CF ₂ ) ₂ F, CH ₂ = CH (CF ₂ ) ₂ F, CH ₂ = CH (CF ₂ ) ₂ H or CH ₂ = CF (CF ₂ ) ₂ H is more preferred, CH ₂ = CH (CF ₂ ) ₂ F is most preferred.
[0020]
Specific examples of the fluorine-containing polymer of the present invention include TFE / HFP copolymer, TFE / E copolymer, TFE / perfluoro (propyl vinyl ether) copolymer, TFE / VDF / HFP copolymer. , TFE / VDF copolymer, chlorotrifluoroethylene / E copolymer and the like are preferable, and TFE / E copolymer is more preferable.
[0021]
In the TFE / E copolymer, the molar ratio of polymerized units based on TFE / polymerized units based on E is preferably 30/70 to 70/30, more preferably 45/55 to 65/35, and 50/50. Most preferred is ~ 65/35. If the molar ratio of polymerized units based on TFE / polymerized units based on E is too small, the heat resistance, weather resistance, chemical resistance, gas barrier property, fuel barrier, etc. of the fluoropolymer will be reduced. The mechanical strength, melt moldability, etc. are reduced. Within this range, the fluoropolymer is excellent in heat resistance, weather resistance, chemical resistance, gas barrier properties, fuel barrier, mechanical strength, melt moldability and the like.
[0022]
Further, when the TFE / E copolymer contains polymerized units based on monomers other than TFE and E, the content thereof is 0.01% with respect to all polymerized units in the TFE / E copolymer. -20 mol% is preferable, 0.1-15 mol% is more preferable, and 1-10 is the most preferable.
[0023]
As TFE / E copolymer, TFE / E / CH ₂ = CH (CF ₂ ) ₄ F copolymer, TFE / E / CH ₂ = CH (CF ₂ ) ₂ F copolymer is more preferred, TFE / E / CH ₂ = CH (CF ₂ ) ₂ The F copolymer is most preferred. CH ₂ = CH (CF ₂ ) ₄ F or CH ₂ = CH (CF ₂ ) ₂ The content of polymer units based on F is preferably 0.01 to 20 mol%, more preferably 0.05 to 15 mol%, and most preferably 0.1 to 10 mol%.
[0024]
In the production method of the fluoropolymer of the present invention, it is preferable to use an acid anhydride as a chain transfer agent and polymerize a monomer containing a fluoroolefin in the presence of a radical polymerization initiator and a polymerization medium.
[0025]
Examples of the acid anhydride used as the chain transfer agent include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, hexahydrophthalic anhydride, hexahydro-4-methylphthalic anhydride, and the like. By chain transfer reaction, an acid anhydride residue is usually introduced at the end of the main chain of the fluoropolymer. The acid anhydride is preferably at least one selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, and hexahydrophthalic anhydride. By controlling the use amount of the acid anhydride, the content of the acid anhydride residue derived from the acid anhydride in the fluoropolymer can be easily controlled.
[0026]
In the present invention, in order to further control the content of the acid anhydride residue of the fluoropolymer and the capacity flow rate of the fluoropolymer, a chain transfer agent other than the acid anhydride may be used in combination as necessary. Is also preferable. Examples of chain transfer agents other than acid anhydrides include alcohols such as methanol and ethanol, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1-fluoroethane, and the like. Hydrocarbons such as chlorofluorohydrocarbon, pentane, hexane, and cyclohexane are listed.
[0027]
As the radical polymerization initiator, those having a decomposition temperature of 0 to 100 ° C. with a half-life of 10 hours are preferred, and those having a decomposition temperature of 20 to 90 ° C. are more preferred. Specific examples include azo compounds such as azobisisobutyronitrile, non-fluorinated diacyl peroxides such as isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide, lauroyl peroxide, peroxydicarbonates such as diisopropylperoxydicarbonate, tert -Peroxyesters such as butylperoxypivalate, tert-butylperoxyisobutyrate, tert-butylperoxyacetate, (Z (CF ₂ ) _p COO) ₂ (Here, Z is a hydrogen atom, a fluorine atom or a chlorine atom, and p is an integer of 1 to 10.) Fluorine-containing diacyl peroxide, potassium persulfate, sodium persulfate, ammonium persulfate And inorganic peroxides.
[0028]
Examples of the polymerization solvent include organic solvents such as fluorinated hydrocarbons, chlorinated hydrocarbons, fluorinated chlorinated hydrocarbons, alcohols and hydrocarbons, and aqueous media.
[0029]
As the polymerization method, solution polymerization, suspension polymerization, and emulsion polymerization are preferable, and solution polymerization using the organic solvent as a polymerization medium is more preferable.
[0030]
In the present invention, the polymerization conditions are not particularly limited, and the polymerization temperature is preferably 0 to 100 ° C, more preferably 20 to 90 ° C. The polymerization pressure is preferably from 0.1 to 10 MPa, more preferably from 0.5 to 3 MPa. The polymerization time is preferably 1 to 30 hours, more preferably 2 to 10 hours.
[0031]
After the completion of the polymerization, the obtained fluoropolymer is separated from the polymerization medium and isolated. As an isolation method, a slurry-like fluoropolymer and water are preferably heated and stirred in a granulation tank, and granulated while distilling off the solvent. In particular, in the case of a TFE / E copolymer, it is preferable that the slurry-like TFE / E copolymer obtained by solution polymerization is granulated and heated under reduced pressure. Even in such an isolation step, the chemical structure of the acid anhydride residue in the fluoropolymer is usually maintained.
[0032]
The fluoropolymer of the present invention is excellent in fuel barrier properties. When a fuel permeability coefficient measured in accordance with the cup method defined in JIS Z-0208 is used as a measure of the fuel barrier property, the lower the fuel permeability coefficient, the better the fuel barrier property. The fluoropolymer of the present invention is characterized by a low fuel permeability coefficient.
[0033]
It is preferable to obtain a multilayer laminate using the fluoropolymer of the present invention. The multilayer laminate preferably contains a fluorine-containing polymer layer (A) and a non-fluorine polymer layer (B). For example, (A) / (B) laminate comprising two layers (A) and (B), and (A) and (B) a layer of a fluoropolymer other than the fluoropolymer of the present invention (C (C) / (A) / (B) laminated body composed of three layers laminated, and (C) / (A) / (B) / (B) laminated bodies, etc., where the number of laminated layers is increased. A laminated body is mentioned. Here, it is preferable that the fluorine-containing polymer layer (A) of the present invention and the non-fluorine polymer layer (B) are preferably laminated so as to be in direct contact with each other, whereby a strongly bonded laminate is obtained. . Moreover, it is also preferable that the multilayer laminated body shape | molded using the fluoropolymer of this invention is a laminated body of (A) and (C). Examples thereof include multilayer laminates such as (A) / (C) laminates, (A) / (C) / (C) laminates, and (C) / (A) / (C) laminates.
[0034]
In the multilayer laminate molded using the fluoropolymer of the present invention, the innermost layer in contact with the fuel is a fluoropolymer layer (A) or a fluoropolymer layer (C), and It is preferable to have conductivity. In particular, it is preferable to use a fluoropolymer layer (A) or a fluoropolymer layer (C) containing conductive carbon black. More preferably, a two-layer laminate comprising a fluoropolymer layer (A) blended with conductive carbon black / a non-fluorine polymer layer (B), or a fluoropolymer blended with conductive carbon black. Three-layer laminate comprising layer (C) / fluorinated polymer layer (A) / non-fluorinated polymer layer (B), fluorinated polymer layer (C) / fluorinated polymer layer (A ) / Non-fluorinated polymer layer (B) / non-fluorinated polymer layer (B) is preferred. In the case of conductivity, the surface resistivity as a measure of conductivity is 1 × 10 ⁹ Ω · cm or less is preferable.
[0035]
The multilayer laminate formed using the fluoropolymer of the present invention preferably contains a non-fluorinated polymer layer (B). Non-fluorinated polymers include polyamides such as polyamide 6, polyamide 66, polyamide 46, polyamide 11, polyamide 12, polyamide MXD6 (semi-aromatic polyamide), polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene. Polyesters such as naphthalate, polyethylene, poly (ethylene / vinyl acetate), polypropylene, polystyrene, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, poly (ethylene / vinyl alcohol), polyacrylonitrile, polyoxymethylene, polyphenylene sulfide, Examples include polyphenylene ether, polycarbonate, polyamideimide, polyetherimide, polysulfone, and polyarylate.
[0036]
As the non-fluorinated polymer, polyamide 6, polyamide 66, polyamide 46, polyamide 11, polyamide 12, and polyamide MXD6 are preferable, and polyamide 11 or polyamide 12 is more preferable.
[0037]
When (B) contains two or more layers in the multilayer laminate, the non-fluorinated polymers of (B) may be the same or different.
[0038]
When the multilayer laminate contains a layer (C) of a fluorine polymer other than the fluorine-containing polymer of the present invention, the fluorine polymer may be a TFE / HFP copolymer, TFE / (Perfluoropropyl vinyl ether) copolymer, TFE / E copolymer, TFE / VDF / HFP copolymer, TFE / VDF copolymer, chlorotrifluoroethylene / E copolymer and the like are preferable. A TFE / E copolymer is more preferable. When (C) contains two or more layers in the multilayer laminate, the fluoropolymers of (C) may be the same or different.
[0039]
The multilayer laminate is preferably obtained by coextrusion molding of a fluorine-containing polymer and a non-fluorine polymer. The coextrusion molding method is a method for obtaining a laminate of two or more layers in the shape of a film, a tube or the like. The molten polymer and the non-fluorinated polymer discharged from the discharge ports of two or more extruders are contacted in a molten state to form a laminate through a die. As the extrusion temperature, the screw temperature is preferably 100 to 350 ° C, and the die temperature is preferably 200 to 350 ° C. The screw rotation speed is not particularly limited, but is preferably 10 to 200 rotations / minute. The residence time of the melt in the extruder is preferably 1 to 20 minutes.
[0040]
As the use of the fluoropolymer of the present invention and the multilayer laminate obtained therefrom, an automotive fuel hose and an automotive fuel tank are preferred. In addition, industrial hoses, food hoses, weather-resistant films, chemical-resistant linings, weather-resistant linings, adhesives of fluoropolymers and non-fluorine polymers, and the like can be mentioned.
[0041]
【Example】
Hereinafter, the present invention will be described with reference to Examples (Examples 1 to 2) and Comparative Examples (Example 3), but the present invention is not limited thereto. The fuel permeability coefficient, acid anhydride content, and Q value were measured by the following methods.
[0042]
[Fuel permeability coefficient]
The fuel permeation coefficient of the fluoropolymer was measured in accordance with the cup method defined in JIS Z-0208. 9.5 to 10 g of fuel E10 (isooctane: toluene: ethanol = 50: 50: 10 volume ratio) is 28.26 cm in permeation area ² Then, the upper part of the cup was covered with a 100 μm-thick fluoropolymer film obtained by press molding, and the fuel permeation coefficient was determined from the amount of mass decrease after holding at 60 ° C. for 10 days. A lower fuel permeability coefficient indicates better fuel barrier properties.
[0043]
[Content of acid anhydride residue (number / number of main chain carbon atoms: 1 × 10 ⁶ Pieces)]
The fluoropolymer was press molded to obtain a 200 μm film. In the infrared absorption spectrum, the absorption peak based on the acid anhydride residue is 1730 cm. ^-1 The absorbance of the peak was measured. K = 1.03 × 10 ⁶ X 1/10 main chain carbon atoms using the relational expression of L / ε ⁶ The content K of acid anhydride residues per unit was calculated. Where L is 1730 cm ^-1 Is the molar extinction coefficient. Note that ε was determined as ε = 200 from the model compound.
[0044]
[Q value (mm ³ / Sec)]
The extrusion rate of the fluoropolymer when extruded from an orifice having a diameter of 2.1 mm and a length of 8 mm under a temperature of 297 ° C. and a load of 7 kg using a Shimadzu flow tester.
[0045]
[Surface resistivity measurement]
Insert copper pins at both ends of the tube and measure the resistance with an ohmmeter.
[0046]
[Example 1]
A polymerization tank equipped with a stirrer with an internal volume of 94 liters was degassed and 110.3 kg of 1-hydrotridecafluorohexane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane (Asahi Glass Co., Ltd.) 10.1 kg of manufactured AK225cb (hereinafter referred to as AK225cb), 6.3 kg of acetic anhydride, CH ₂ = CH (CF ₂ ) ₂ 730 g of F was charged and 8.5 kg of TFE and 1.3 kg of E were press-fitted. The temperature in the polymerization tank was raised to 66 ° C., and 289 mL of a 1% by mass AK225cb solution of tert-butylperoxypivalate was charged as a polymerization initiator to initiate polymerization. A monomer mixed gas having a composition TFE / E = 60/40 (molar ratio) was continuously charged so that the pressure was kept constant during the polymerization. 5.2 hours after the start of polymerization, when 8.0 kg of the monomer mixed gas was charged, the temperature in the polymerization tank was lowered to room temperature and purged to normal pressure.
[0047]
The obtained slurry-like fluoropolymer 1 was put into a 200 L granulation tank charged with 75 kg of water, and then heated to 105 ° C. while stirring, and granulated while distilling and removing the solvent. The obtained granulated product was dried at 150 ° C. for 5 hours, whereby 8.2 kg of granulated product 1 of fluoropolymer 1 was obtained.
[0048]
From the results of melt NMR analysis and fluorine content analysis, the composition of the fluoropolymer 1 is TFE-based polymer units / E-based polymer units / CH. ₂ = CH (CF ₂ ) ₂ The molar ratio of polymer units based on F was 58.1 / 39.1 / 2.8. Further, from the results of infrared absorption spectrum analysis, the content of acetic anhydride residue in the fluoropolymer is 1 × 10 main chain carbon atoms. ⁶ It was 494 pieces per piece. Fluoropolymer 1 has a melting point of 238 ° C. and a Q value of 27 mm. ³ / Sec, fuel permeability coefficient is 2.48 gmm / m ² / 24h.
[0049]
Using an extruder, the granulated product 1 was melt-kneaded at 280 ° C. and a residence time of 2 minutes to produce pellets 1. In addition, 100 parts of the granulated product 1 and 15 parts of carbon black (manufactured by Electrochemical Co., Ltd., granular acetylene black) were melt-kneaded using an extruder at 260 ° C. and a residence time of 2 minutes to obtain a conductive fluorine-containing material. A pellet 2 of polymer 1b was prepared.
[0050]
Polyamide 12 (manufactured by Ube Industries, 3030JLX2) is supplied to the cylinder that forms the outer layer, pellet 1 is supplied to the cylinder that forms the intermediate layer, and pellet 2 is supplied to the cylinder that forms the inner layer. Moved to. The heating temperatures in the transport zone for polyamide 12, pellet 1 and pellet 2 were 260 ° C., 280 ° C. and 280 ° C., respectively. Three-layer coextrusion was performed at a temperature of the common die of 280 ° C. to obtain a three-layer laminated tube. The outer diameter of the laminated tube is 8 mm, the inner diameter is 6 mm, and the thickness is 1 mm. The thickness of the outer layer of polyamide 12, the intermediate layer of the fluoropolymer 1 and the inner layer of the conductive fluoropolymer 1b is 0.7 mm. 0.1 mm and 0.2 mm. The surface resistivity of the inner layer is 2 × 10 ⁵ It was Ω · cm.
[0051]
The peel strength between each layer of the obtained tube was measured. The intermediate layer of the fluoropolymer 1 and the inner layer of the conductive fluoropolymer 1b could not be peeled, and the material was partially broken to show a high adhesive force. The peel strength between the intermediate layer of the fluoropolymer 1 and the outer layer of the polyamide 12 was 33.2 N / cm, indicating a high peel strength.
[0052]
[Example 2]
Except for charging 104.5 kg of 1-hydrotridecafluorohexane, 19.1 kg of AK225cb and 3.8 kg of acetic anhydride before polymerization, 8 of granulated product 2 of fluoropolymer 2 was obtained in the same manner as in Example 1. 0.0 kg was obtained. The polymerization time was 5.8 hours.
[0053]
From the results of melt NMR analysis and fluorine content analysis, the composition of the fluoropolymer 2 is TFE-based polymer units / E-based polymer units / CH. ₂ = CH (CF ₂ ) ₂ The molar ratio of polymerized units based on F was 57.9 / 39.5 / 2.6. Further, from the results of infrared absorption spectrum analysis, the content of acetic anhydride residue in the fluoropolymer 2 is 1 × 10 main chain carbon atoms. ⁶ It was 330 pieces per piece. Fluoropolymer 2 has a melting point of 241 ° C. and a Q value of 31 mm. ³ / Sec, fuel permeation coefficient is 2.13 gmm / m ² / 24h.
[0054]
Using an extruder, the granulated product 2 was melt-kneaded at 260 ° C. and a residence time of 2 minutes to prepare pellets 3. Further, 100 parts of the granulated product 2 and 15 parts of carbon black (granular acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd.) were melt-kneaded using an extruder at 260 ° C. and a residence time of 2 minutes to obtain conductive fluorine-containing material. A pellet 4 of polymer 2b was prepared.
[0055]
The polyamide 12 of Example 1 was supplied to the cylinder forming the outer layer, the pellets 4 were supplied to the cylinder forming the inner layer, and each was transferred to the transport zone of the cylinder. The heating temperatures in the transport zone of polyamide 12 and pellet 4 were 260 ° C. and 280 ° C., respectively. Two-layer coextrusion was performed at a temperature of the common die of 280 ° C. to obtain a two-layer laminated tube. The outer diameter of the laminated tube was 8 mm, the inner diameter was 6 mm, and the thickness was 1 mm. The thicknesses of the outer layer of polyamide 12 and the inner layer of the conductive fluoropolymer 2b were 0.7 mm and 0.3 mm, respectively. The surface resistivity of the inner layer is 3 × 10 ⁵ It was Ω · cm. The peel strength between the inner layer and the outer layer was 25.3 N / cm, indicating a high peel strength.
[0056]
[Example 3]
Prior to polymerization, 93.7 kg of 1-hydrotridecafluorohexane, 34.7 kg of AK225cb, CH ₂ = CH (CF ₂ ) ₂ In the same manner as in Example 1 except that 730 g of F was charged and acetic anhydride was not used, 8.5 kg of granulated product 3 of fluoropolymer 3 was obtained. The polymerization time was 6.2 hours.
[0057]
From the results of melt NMR analysis and fluorine content analysis, the composition of the fluoropolymer 3 is TFE-based polymer units / E-based polymer units / CH. ₂ = CH (CF ₂ ) ₂ The molar ratio of polymerized units based on F was 57.9 / 39.5 / 2.6. Further, from the result of infrared absorption spectrum analysis, the content of acetic anhydride residue in the fluoropolymer 3 is 1 × 10 main chain carbon atoms. ⁶ It was 0 per piece. Fluoropolymer 3 has a melting point of 240 ° C. and a Q value of 25 mm. ³ / Sec, fuel permeation coefficient is 1.75 gmm / m ² / 24h.
[0058]
Using an extruder, the granulated product 3 was melted and kneaded at 260 ° C. and a residence time of 2 minutes to prepare pellets 5. In addition, 100 parts of the granulated product 3 and 15 parts of carbon black (granular acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd.) were melt-kneaded using an extruder at 260 ° C. for a residence time of 2 minutes to produce conductive fluorine-containing material. A pellet 6 of the polymer 3b was prepared.
[0059]
The polyamide 12 of Example 1 was supplied to the cylinder forming the outer layer, the pellet 6 was supplied to the cylinder forming the inner layer, and each was transferred to the transport zone of the cylinder. The heating temperatures in the transport zone of polyamide 12 and pellet 6 were 260 ° C. and 280 ° C., respectively. Two-layer coextrusion was performed at a temperature of the common die of 280 ° C. to obtain a two-layer laminated tube. The outer diameter of the laminated tube is 8 mm, the inner diameter is 6 mm, and the thickness is 1 mm. The outer layer of polyamide 12 and the inner layer of the conductive fluoropolymer 3b are 0.7 mm and 0.3 mm, respectively. It peeled easily from the outer layer. The surface resistivity of the inner layer is 5 × 10 ⁵ It was Ω · cm.
[0060]
【The invention's effect】
The fluoropolymer of the present invention has a low fuel permeability coefficient, excellent fuel barrier properties, and excellent adhesion to non-fluorinated polymers. Moreover, it is excellent in stress crack resistance.
[0061]
The fluorine-containing polymer of the present invention is easy to co-extrusion with a fluorine-based polymer other than a non-fluorine polymer and a fluorine-containing polymer, and gives a laminate having excellent peel strength. The laminate is suitable for a fuel hose. In addition, the fluoropolymer of the present invention is suitable as a constituent material of a layer that is in direct contact with the non-fluorine polymer layer in the laminate.

Claims (3)

A fluorine-containing polymer containing an acid anhydride residue derived from a chain transfer agent, wherein the content of the acid anhydride residue is 100 to 1000 per 1 × 10 ⁶ main chain carbon atoms A fluorine-containing polymer characterized by The method for producing a fluoropolymer according to claim 1, wherein an acid anhydride is used as the chain transfer agent, and the monomer containing the fluoroolefin is polymerized in the presence of a radical polymerization initiator and a polymerization medium. The method for producing a fluoropolymer according to claim 2, wherein the acid anhydride is at least one selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, and hexahydrophthalic anhydride.