JP2003268038A - Fluorine-containing polymer and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorine-containing polymer having excellent mechanical characteristics and excellent adhesion to another material, and to provide a method for producing the same. <P>SOLUTION: This fluorine-containing polymer has such a melt flow rate and a number of end groups derived from its polymerization initiator as to satisfy the following inequity: Y>8.6X+120, wherein Y is the number of the end groups derived from the polymerization initiator based on 10<SP>6</SP>carbon atoms in the fluorine-containing polymer and is in a range of 200-2000, and X is the melt flow rate (g/10 min) measured under a load of 5 kg at a temperature higher than the melting point of the fluorine-containing polymer by 50°C and is in a range of 0.5-200. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a specific fluoropolymer, and more particularly to a fluoropolymer having excellent adhesiveness to various materials and a method for producing the same.

[0002]

2. Description of the Related Art Fluorine resins are excellent in chemical resistance, weather resistance, heat resistance, chemical resistance, gas barrier properties, fuel barrier properties, non-adhesiveness, etc. and are used in a wide variety of fields. The fluororesin is used not only as a single molded body but also as a laminated body in which other materials are laminated depending on the application.
Usually, the laminate is manufactured by a method of co-extruding a plurality of thermoplastic resins, a method of heat-sealing a film made of a plurality of thermoplastic resins, or the like.

However, when a plurality of thermoplastic resins differ greatly in characteristics, there has been a problem that the interlayer adhesion of the obtained laminate is not sufficient. In particular, since the fluororesin is excellent in non-adhesiveness, the adhesiveness with other materials, particularly the non-fluorine thermoplastic resin is remarkably low, and a multilayer film or a multilayer film obtained by laminating the fluororesin and the non-fluorine thermoplastic resin The tube did not have sufficient interlayer adhesion.

As a method for improving this point, there is known a method of adhering to another material by performing sodium etching, plasma treatment, photochemical treatment or the like on the surface of a film made of a fluororesin, but the adhesive strength is not good. It was sufficient and the productivity was low because it could not be produced by coextrusion. Although an adhesive method using an adhesive is also known, the adhesive force is not sufficient and the productivity is low.

In WO99 / 45044, a fluorine-containing polymer having a carbonate end group, which is obtained by polymerizing a fluorine-containing monomer with a polymerization initiator having a carbonate group, has an adhesive property with other materials. It is described as excellent in. However, to increase the content of carbonate end groups in order to further improve the adhesiveness with other materials,
It was found that when the amount of the polymerization initiator used was simply increased, the polymerization rate increased, the polymerization reaction could not be controlled, and the mechanical properties of the obtained fluoropolymer were not sufficient.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide a fluoropolymer having excellent mechanical properties and adhesiveness to other materials, and a method for producing the same. .

[0007]

The present invention is characterized in that the melt flow rate of the fluoropolymer and the number of terminal groups derived from the polymerization initiator have the relationship of the following formula (1). Provide a polymer. Y> 8.6X + 120 (1) Here, Y is the number of terminal groups derived from the polymerization initiator for 10 ⁶ carbons in the fluoropolymer, which is 200 to 2000.
X is a melt flow rate at a temperature 50 ° C. higher than the melting point of the fluoropolymer under a load of 5 kg.
~ 200 g / 10 min.

Further, the present invention provides the method for producing a fluoropolymer according to claim 1 or 2, wherein the fluoroolefin is polymerized in the presence of a polymerization initiator and a polymerization medium. Provided is a method for producing a fluoropolymer characterized by having a pressure of 0.8 MPa.

The fluorine-containing polymer in the present invention includes
A fluorine-containing polymer obtained by polymerizing a fluorine-containing olefin or a fluorine-containing polymer obtained by copolymerizing a fluorine-containing olefin with another monomer is preferable.

As the fluorine-containing olefin, tetrafluoroethylene (hereinafter referred to as TFE), vinylidene fluoride, chlorotrifluoroethylene (hereinafter referred to as CTFE), vinyl fluoride, trifluoroethylene, hexafluoropropylene (hereinafter referred to as HFP), CF
₂ = CFR _f (where R _f is a polyfluoroalkyl group having 2 to 10 carbon atoms; the same applies hereinafter) and the like. The fluorinated olefins may be used alone or in combination of two or more.

Other monomers include CF ₂ = CF
OCF ₃ , CF ₂ = CFOR _f , CF ₂ = CFO (CF
₂ ) _n COZ (where Z is hydrogen, hydroxyl group, halogen,
It is an alkoxyl group. ) And other fluorovinyl ethers, ethylene (hereinafter referred to as E), olefins such as propylene and butene, and the like. The other monomers may be used alone or in combination of two or more.

The above-mentioned fluoropolymer is TFE / E
Copolymer, TFE / HFP copolymer, TFE / perfluoro (propyl vinyl ether) copolymer, CTFE /
E copolymer, TFE / vinylidene fluoride / HFP copolymer, TFE / propylene copolymer and the like can be mentioned. In particular, TFE / E copolymer, TFE / HFP copolymer, T
The FE / (perfluoropropyl vinyl ether) copolymer is preferable because it is excellent in thermal stability, moldability, mechanical properties and the like.

Particularly when used for fuel hose applications, the fluoropolymer is preferably a TFE / E copolymer, and it is a TFE-based polymerized unit, an E-based polymerized unit, and a TFE / E-based polymerized unit. More preferably, it is a fluoropolymer containing polymerized units based on a polymerizable monomer. The fluorine-containing polymer has a molar ratio of polymerized units based on TFE to polymerized units based on E of 40/60 to 8
Most preferred is a TFE / E copolymer containing 0 to 20 mol% of polymerized units based on a monomer copolymerizable with TFE and E, based on the total amount of the copolymer. TF
If the molar ratio of the polymer units based on E to the polymer units based on E is too small, the heat resistance, weather resistance, chemical resistance, gas barrier properties, fuel barrier properties, etc. of the fluoropolymer will deteriorate, and if the molar ratio is too large. Mechanical strength, melt moldability, etc. decrease. T
Polymerized units based on FE, polymerized units based on E, and TF
Polymerized units based on E and a monomer copolymerizable with E are
The type and amount are appropriately selected for the purpose of adjusting the melting point of the fluoropolymer, improving mechanical properties, improving adhesiveness, and the like.

The monomers copolymerizable with TFE and E include vinylidene fluoride, chlorotrifluoroethylene, hexafluoropropylene, CF ₂ ═CFR _f and C.
F ₂ = CHR _f , CH ₂ = CHR _f , CH ₂ = CFR _f
Fluorine-containing olefins (excluding TFE), etc.,
CF ₂ = CFOR _f , CF ₂ = CFO (CF ₂ ) _n CO
Unsaturation such as fluorovinyl ethers such as Z, olefins such as propylene and butene (but excluding E), aliphatic vinyl carboxylates such as vinyl acetate and vinyl butanoate, maleic anhydride, itaconic anhydride, citraconic anhydride, etc. Examples thereof include acid anhydrides, vinyl ethers such as hydroxybutyl vinyl ether and glycidyl vinyl ether. T
The monomers copolymerizable with FE and E may be used alone or in combination of two or more.

5 kg of the fluoropolymer of the present invention
The melt flow rate (hereinafter referred to as MFR) at a temperature 50 ° C. higher than the melting point of the fluoropolymer under a load of 0.5 to 200 g / min. Preferably 1-12
0 g / min, more preferably 2-70 g / mi
n.

The number of terminal groups derived from the polymerization initiator for the 10 ⁶ carbons in the fluoropolymer of the present invention is 200 to.
It is 2000 pieces. The number is preferably 250 to 1500, and more preferably 300 to 1000.

In the fluoropolymer of the present invention, 5 kg
MFR at a temperature 50 ° C. higher than the melting point of the fluoropolymer under a load of Y is represented by Y, the number of terminal groups derived from the polymerization initiator for 10 ⁶ carbons is represented by X, and X and Y are represented by the following formulas: There is a relationship of (1). Y> 8.6X + 120 (1) When Y is (8.6X + 120) or less, mechanical properties such as crack resistance and adhesiveness cannot be achieved at the same time.

Examples of the method for producing the fluoropolymer in the present invention include polymerization methods such as emulsion polymerization, solution polymerization and suspension polymerization. As a polymerization medium in the solution polymerization, C is used.
Hydrochlorofluorocarbons such as ClF ₂ CF ₂ CClFH, CF ₃ CF ₂ CF ₂ CF ₂ CH ₂ CH ₃ ,
Hydrofluorocarbons such as CF ₃ CF (CF ₃ ) CFHCFHCF ₃ , chlorofluorocarbons such as CCl ₃ F and C ₂ Cl ₃ F ₃ , alcohols having 4 to 6 carbon atoms such as sec-butyl alcohol and tert-butyl alcohol And the like. In suspension polymerization and emulsion polymerization, water or a mixed medium of water and another medium is used. The other medium is preferably the same as the medium used in the solution polymerization. In particular, suspension polymerization or solution polymerization is more preferable.

In the method for producing a fluoropolymer of the present invention, it is preferable to use a very small amount of the chain transfer agent, and it is more preferable not to use it at all. The chain transfer agent is used to adjust the MFR of the fluoropolymer and forms the terminal group of the fluoropolymer, and thus prevents the formation of the terminal group derived from the polymerization initiator. Examples of the chain transfer agent include hydrocarbons such as hexane and cyclohexane, alcohols such as methanol and ethanol, and halogenated hydrocarbons such as trichlorofluoromethane and dichloropentafluoropropane. When a chain transfer agent is used, the amount used is appropriately selected according to the chain transfer characteristics of each chain transfer agent, but is preferably 5 parts by mass or less with respect to 100 parts by mass of the polymerization medium, and 1 part by mass. The following is more preferable.

The polymerization initiator used for producing the fluorine-containing polymer in the present invention is one or more functional groups selected from the group consisting of ester group, carboxylic acid group, carbonate group, amino group and cyano group. A peroxide-based polymerization initiator or an azo-based polymerization initiator having The polymerization initiator produces a fluorinated polymer in which the terminal group derived from the polymerization initiator is at least one selected from the group consisting of an ester group, a carboxylic acid group, a carbonate group, an amino group and a cyano group. . More preferably, it is a peroxide type polymerization initiator.

As specific examples, diisopropyl peroxydicarbonate, succinic acid peroxide,
Examples thereof include dimethylazobismethylpropionate, azobisisobutyronitrile and azobismethylpropionamidine dihydrochloride. Diisopropyl peroxydicarbonate is more preferred, and a carbonate group is preferred as the terminal group of the fluoropolymer.

The amount of the polymerization initiator concentration used is 1 of the polymerization medium.
2.0 × ¹⁰ -6 ~5.0 × ^{10 -5} mol are preferred with respect to L, and more preferably 5.0 × ^{10 -6} ~5.0 × ¹⁰ -6 mol. If the amount of the polymerization initiator used is too large, the control of the polymerization rate is insufficient, and if it is too small, the polymerization rate is slow,
Neither is an industrial manufacturing method. When the amount of the polymerization initiator used is within this range, the polymerization rate can be appropriately controlled, which is preferable. The method of adding the polymerization initiator is not particularly limited, and may be added all at once at the start of the polymerization or continuously during the polymerization. The addition method is appropriately selected depending on the decomposition reactivity of the polymerization initiator and the polymerization temperature.

The method for producing the fluorine-containing copolymer of the present invention is as follows:
In the method for producing a fluoropolymer in which a fluoroolefin is polymerized in the presence of a polymerization initiator and a polymerization medium, the polymerization pressure is 0.2 to 0.8 MPa. Preferably 0.4-
It is 0.7 MPa. When the polymerization pressure is within this range, the polymerization rate can be easily controlled even if the amount of the polymerization initiator used is increased, and a fluoropolymer satisfying the formula (1) can be produced. When the polymerization pressure exceeds 0.8 MPa, the polymerization rate becomes too fast when the amount of the polymerization initiator used is increased, and
A fluoropolymer satisfying the formula (1) cannot be obtained. When the polymerization pressure is less than 0.2, the polymerization rate is slow and a fluoropolymer having excellent mechanical properties cannot be obtained.

The polymerization temperature is appropriately selected depending on the kind of the polymerization initiator, but is preferably 0 to 100 ° C, preferably 20 to 85 ° C.
Is more preferable.

The polymerization time is not particularly limited, but is preferably 0.5 hour to 30 hours, more preferably 2 hours to 10 hours. If it is less than 0.5 hours, uniform polymerization is difficult, and 3
Productivity is low for 0 hours or more.

The monomer concentration is adjusted according to the polymerization pressure adopted. When producing a TFE / E copolymer, the range of 0.1-0.9 mol is preferable to 1 L of the polymerization medium.

The concentration of the fluoropolymer produced during the polymerization is preferably 5 to 150 g per liter of the polymerization medium.
If it is less than 5 g, the productivity will be low, and if it is more than 150 g, a heterogeneous fluoropolymer will tend to be produced.

In the present invention, the reason why the fluorine-containing polymer is particularly excellent in adhesiveness is that the number of terminal groups derived from the polymerization initiator is larger than the number of terminal groups obtained by a polymerization method in which the polymerization pressure exceeds 0.8 MPa. This is probably because there are many. In the polymerization method in which the polymerization pressure is higher than 0.8 MPa, since the chain transfer agent is used to obtain a fluoropolymer having an appropriate MFR, the number of terminal groups derived from the polymerization initiator is reduced. Further, since the number of terminal groups derived from the polymerization initiator is increased, when the amount of the polymerization initiator used is increased at the time of production, the polymerization rate becomes faster, the resulting fluoropolymer becomes heterogeneous, and mechanical properties are increased. Is reduced. On the other hand, in the method for producing the fluoropolymer of the present invention, the polymerization pressure is 0.8 MPa or less, so that the polymerization rate is easily controlled even if the amount of the polymerization initiator is increased. A fluoropolymer having a large number of terminal groups derived from the polymerization initiator and excellent in moldability and mechanical properties can be obtained. The relationship is represented by the above formula (1).
A fluoropolymer that does not satisfy the formula (1) has insufficient adhesiveness or mechanical properties.

As the thermoplastic resin suitable for lamination with the fluoropolymer of the present invention, fluororesins other than the fluoropolymer, polyolefin resins, polyamide resins, polyester resins, polystyrene resins, ABS resins, BS resins, M
BS resin, EVA resin, acrylic resin, polyurethane resin, polyimide resin, polyphenylene sulfide resin,
Examples thereof include vinyl chloride resin, polyolefin-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, polyester-based thermoplastic elastomer, polybutadiene-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, polyvinyl chloride thermoplastic elastomer, and fluorothermoplastic elastomer.

Fluorine resins such as ETFE, PFA and FEP, polyolefin resins such as polyethylene and polypropylene, polyamide resins such as polyamide 6, polyamide 11 and polyamide 12, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, and polymethyl. An acrylic resin such as methacrylate. For fuel hose use, a polyamide resin or a polyamide-based thermoplastic elastomer is more preferable, and polyamide 6, polyamide 11 and polyamide 12 are most preferable. Polyamide resin has relatively low permeability to fuel oil and is excellent in mechanical strength.

When a molded product is molded using the fluoropolymer of the present invention, it is also preferable that the molded product contains various additives. As the additive, a filler, an antistatic agent,
Reinforcing fibers, pigments, plasticizers, adhesion-imparting agents, silane coupling agents, titanate coupling agents and the like can be mentioned.

In the case of use as a fuel hose, it is also preferable to impart conductivity for the purpose of antistatic as an inner layer made of a fluoropolymer which comes into contact with fuel. The volume resistivity of the inner layer having conductivity (hereinafter, also referred to as a conductive layer) is 1 to 1 ×.
10 ⁹ Ω · cm is preferable, 1 × 10 ² to 1 × 10 ⁹ Ω
-Cm is more preferable. Within this range, the antistatic property is excellent. The fluoropolymer preferably contains a conductive additive in order to impart conductivity. The content of the conductive additive is 1 to 100 parts by mass of the fluoropolymer.
30 parts by mass is preferable, and 5 to 20 parts by mass is more preferable.

Specific examples of the conductive additive include powders or fibers of metal or carbon, powders of metal oxides, non-conductive powders whose surface is treated to be conductive, and the like. Examples of the powder or fiber of metal or carbon include powder of metal such as copper, nickel and silver, fiber of metal such as iron and stainless steel, carbon black and carbon fiber. Examples of the metal oxide include zinc oxide and copper oxide. Examples of the non-conductive powder that has been made conductive include powders such as glass beads and titanium oxide whose surfaces are metallized by metal sputtering, electroless plating or the like. In particular, conductive acetylene black, conductive Ketjen black and the like are preferable.

As a method for pelletizing the fluoropolymer, extrusion molding using a single-screw or twin-screw extruder is preferable. The cylinder temperature of the extruder is 100 to 350 ° C., the crosshead temperature and the die temperature are 200 to 350, respectively.
℃, crosshead temperature and die temperature 200 ~
350 ° C is preferred. The screw rotation speed is not particularly limited, but is preferably 10 to 200 rotations / minute. The residence time of the fluorocopolymer in the extruder is preferably 1 to 10 minutes. The discharge hole of the die preferably has a diameter of 2 to 20 mm. The string-shaped fluorine-containing copolymer melted and discharged from the discharge hole is cooled and solidified with water or air while being stretched, cut by a cutter, and is a columnar pellet having a length of 1 to 5 mm and a diameter of 1 to 5 mm. Is obtained.

The laminate containing the layer of the fluoropolymer of the present invention is preferably obtained by coextrusion molding the fluoropolymer and the non-fluorine thermoplastic resin. Usually, the co-extrusion molding method is a method of obtaining a laminate having two or more layers in the shape of a film, a tube or the like. The melt coming out from the discharge ports of two or more extruders passes through a die while being in contact with each other in a molten state, and is formed into a laminate. Regarding the extrusion temperature, the screw temperature is preferably 100 to 350 ° C, and the die temperature is 200 to
350 ° C is preferred. 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.

In the laminate containing the fluorine-containing copolymer layer of the present invention, the peel strength between the fluorine-containing copolymer layer and the non-fluorine-containing polymer layer is preferably 35 N / cm or more, and 40 N / cm or more. cm or more is more preferable, and 45 N / cm or more is the most preferable.

The use of the fluorine-containing copolymer of the present invention and the laminate obtained therefrom is as a fuel hose for automobiles,
Automotive fuel tanks, industrial hoses, food hoses,
Examples thereof include a weather resistant film, a chemical resistant lining, a weather resistant lining, and an adhesive material of a fluoropolymer and a non-fluorine polymer.

[0038]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. The composition of the fluorine-containing copolymer, the number of carbonate end groups, MFR,
The MIT bending test, volume resistivity and peel strength were measured by the following methods.

[Composition of fluorine-containing copolymer (unit: molar ratio)] The molar ratio of polymerized units in the fluorine-containing copolymer was measured by fluorine content analysis and ¹⁹ F-NMR analysis under melting.

[Number of carbonate end groups (unit: pieces)]
The number of carbonate end groups derived from the polymerization initiator was calculated with respect to 10 ⁶ carbons in the fluoropolymer by the method described in WO99 / 45044.

[Melting point of fluorocopolymer (unit: ° C)]
Seiko Denshi DSC was used to record the melting peak when the temperature was raised at a rate of 10 ° C./min, and the temperature corresponding to the maximum value was taken as the melting point.

[MFR (unit: g / 10 min)] Using a melt indexer manufactured by Toyo Seiki Seisaku-sho, Ltd., at a temperature 50 ° C. higher than the melting point of the fluorocopolymer to be measured, 5
Under a load of kg, the weight (g) of the fluorinated copolymer flowing out from a nozzle having a diameter of 2 mm and a length of 8 mm in a unit time (10 minutes) is measured.

[MIT bending test (unit: times)] AS
It was measured according to TM D2176. Ie width 1
A test piece of 2.5 mm, a length of 130 mm, and a thickness of 0.23 mm was mounted on a MIT measuring machine manufactured by Toyo Seiki Seisakusho, and a load of 1.
The test piece was bent under the conditions of 25 kg, the left and right bending angles were 135 degrees, and the bending number was 175 times / minute, and the number of times until the test piece was cut was measured. This test is a bending fatigue test of a fluorine-containing copolymer and serves as an index of crack resistance. The larger the number of times, the better the crack resistance.

[Volume specific resistance (unit: Ω · cm)] A 100 μm film obtained by press-molding a fluoropolymer was used as a sample, and Loresta AP manufactured by Mitsubishi Chemical was used.
The volume resistivity value (Ω · cm) was measured by bringing a four-ended needle probe into contact with the film surface with a load of 1 kg.

[Tube peeling strength (unit: N / cm)]
The tube was cut into a length of 10 cm and cut in half in the length direction to obtain a test piece, and the peel strength between the fluorocopolymer layer and the polyamide layer was measured.

Example 1 An autoclave equipped with a stirrer having an internal volume of 94 liters was degassed, and 19.7 k of deionized water was added.
g, 77.1 of perfluoropentyldifluoromethane
kg, CH ₂ = 427 g of CH (CF ₂ ) ₂ F, TFE
3.36 kg and 127 g of E were pressed in, and the temperature inside the autoclave was raised to 66 ° C. At this time, the pressure is 0.65MP
It was a. 72 g of diisopropyl peroxydicarbonate was charged as a polymerization initiator to start the polymerization. TFE / E = 60 / so that the pressure is constant during the polymerization
A monomer mixture gas having a molar ratio of 40 was continuously charged.
Further, CH ₂ ═CH (CF ₂ ) ₂ F in an amount corresponding to 6 mol% with respect to the total number of moles of TFE and E charged during the polymerization was continuously charged. 5.6 hours after the initiation of polymerization, when 11.5 kg of the monomer mixed gas was charged, the internal temperature of the autoclave was cooled to room temperature and the internal pressure of the polymerization layer was purged to normal pressure. The obtained slurry-like fluorocopolymer 1 was put into a 300 L granulation tank charged with 100 kg of water, heated to 105 ° C. with stirring, and granulated while removing the solvent by distillation. The obtained granulated product is dried at 135 ° C. for 3 hours to give a granulated product 1 of the fluorocopolymer 1.
12.1 kg of was obtained.

The composition of the fluorinated copolymer 1 is such that TFE-based polymer units / E-based polymer units / CH ₂ ═CH (C
The molar ratio of polymerized units based on F ₂ ) ₂ F is 57.2 / 3.
It was 7.0 / 5.8, and the number of carbonate end groups derived from the polymerization initiator in the fluorinated copolymer 1 was 359. Melting point is 205 ° C, MFR measured at 255 ° C is 2
0.3g / 10min, MIT bending number is 1660
It was 00 times. 8.6X + 120 = 295 <359
And the fluorinated copolymer 1 satisfied the relationship of the formula (1).

15 parts by mass of conductive carbon black (granular acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd.) was added to 100 parts by mass of the granulated product 1, and 2 parts were mixed using an extruder.
Melt-kneading was carried out at 60 ° C. for a residence time of 2 minutes to prepare pellets 1 of the conductive fluorocopolymer 1b.

Polyamide 12 is used for the cylinder forming the outer layer.
(Ube Industries, Ltd., 3030JLX2) was supplied, and the pellet 1 was supplied to the cylinder forming the inner layer, and each was transferred to the transport zone of the cylinder. The heating temperature in the transport zone for polyamide 12 and pellet 1 was set to 240 each.
C. and 290.degree. The temperature of the co-die is 260 ° C and is 3
Layer coextrusion was performed 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 m.
The outer layer of the polyamide 12 and the inner layer of the conductive fluorocopolymer 1b were 0.7 mm and 0.3 mm, respectively. The peel strength between layers of the obtained tube was 45.5N.
Was / cm. The volume resistivity of the inner layer is 1.2 × 10
It was ⁴ Ω · cm.

[Example 2] Initially 2.20 kg of TFE, E
Granules 2 of the fluorinated copolymer 2 in the same manner as in Example 1 except that 76 g of CH ₂ ═CH (CF ₂ ) ₂ F and 310 g of CH ₂ ═CH (CF ₂ ) ₂ F are charged and 149 g of diisopropyl peroxydicarbonate as a polymerization initiator is used. 12.0 kg was obtained. The polymerization pressure was 0.41 MPa, and the polymerization time was 7.2 hours.

The composition of the fluorinated copolymer 2 is such that TFE-based polymer units / E-based polymer units / CH ₂ ═CH (C
The molar ratio of polymerized units based on F ₂ ) ₂ F is 57.0 / 3.
It was 7.3 / 5.7. The melting point was 204 ° C. and 254 ° C., the MFR was 56.5 g / 10 min, the MIT bending number was 85,000, and the number of carbonate end groups derived from the polymerization initiator was 672 per 10 ⁶ carbons. 8.6X + 120 = 605 <672, and the fluorinated copolymer 2 satisfied the relationship of the formula (1).

The granulated product 2 was melt-kneaded with an extruder at 260 ° C. for a residence time of 2 minutes to prepare pellets 2 of the fluorocopolymer 2.

The cylinder forming the outer layer is fed with the polyamide 12 of Example 1, the cylinder forming the intermediate layer is fed with the pellet 2 and the cylinder forming the inner layer is fed with the pellet 1 of Example 1, respectively in cylinder transport. Transferred to the zone. The heating temperature in the transport zone for polyamide 12, pellets 2, and pellets 1 is 240 ° C, 260 ° C, respectively.
The temperature was 290 ° C. The temperature of the co-die was set to 260 ° C. and three-layer coextrusion was performed to obtain a three-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 outer layer of the polyamide 12, the intermediate layer of the fluorocopolymer 2 and the inner layer of the conductive fluorocopolymer 1b were 0.7 mm, respectively. It was 0.1 mm and 0.2 mm. The peel strength between the layers of the obtained tube was measured. The inner layer and the intermediate layer could not be peeled off, and the material was partially broken to show high adhesion. The peel strength between the outer layer and the intermediate layer was 52 N / cm.

[Comparative Example 1] 11.0 k of TFE at the initial stage
g, 381 g of E, 85 of CH ₂ ═CH (CF ₂ ) ₂ F
0 g was used and 232 g of pentane was newly charged, and 1 g of diisopropyl peroxydicarbonate as a polymerization initiator was added.
In the same manner as in Example 1 except that 8 g was used, 12.5 kg of the granulated product 3 of the fluorocopolymer 3 was obtained. Polymerization pressure is 1.4
The polymerization time was 1 MPa and the polymerization time was 6.0 hours.

The composition of the fluorinated copolymer 3 is such that TFE-based polymer units / E-based polymer units / CH ₂ ═CH (C
The molar ratio of polymerized units based on F ₂ ) ₂ F is 57.0 / 3.
It was 7.2 / 5.8. The melting point was 204 ° C., the MFR measured at 254 was 19.6 g / 10 min, the MIT bending number was 175,000, and the number of carbonate end groups derived from the polymerization initiator was 262 per 10 ⁶ carbons. 8.6X + 120 = 289> 262, and the fluorinated copolymer 3 did not satisfy the relationship of the formula (1).

15 parts by mass of the conductive carbon black of Example 1 was mixed with 100 parts by mass of the granulated product 3, and the mixture was melt-kneaded at 260 ° C. for a residence time of 2 minutes using an extruder to obtain a conductive material. Pellets 3 of the fluorocopolymer 3b were prepared.

The polyamide 12 of Example 1 was fed to the cylinder forming the outer layer, and the pellets 3 were fed to the cylinder forming the inner layer.
Were supplied and transferred to the transport zone of the cylinder. The heating temperatures of the polyamide 12 and the pellet 3 in the transport zones were 240 ° C. and 290 ° C., respectively. Two layers were coextruded at a co-die temperature of 260 ° C. to obtain a two-layer laminated tube. The outer diameter of the laminated tube is 8 mm,
The inner diameter was 6 mm, the thickness was 1 mm, and the outer layer of polyamide 12 and the inner layer of conductive fluorocopolymer 3b were 0.7 mm and 0.3 mm, respectively. The peel strength between layers of the obtained tube was 30 N / cm, which was not sufficient. The volume resistivity of the inner layer was 1.5 × 10 ⁴ Ω · cm.
In this comparative example, the obtained fluoropolymer had a high MIT bending number and excellent crack resistance, but had low adhesiveness.

[Comparative Example 2] Initially, TFE was 11.0 k.
g, 381 g of E, 85 of CH ₂ ═CH (CF ₂ ) ₂ F
0 g was used and 397 g of pentane was newly charged, and 2 g of diisopropyl peroxydicarbonate as a polymerization initiator was added.
In the same manner as in Example 1 except that 1 g was used, 11.7 kg of the granulated product 4 of the fluorocopolymer 4 was obtained. Polymerization pressure is 1.3
The polymerization time was 8 MPa and the polymerization time was 8.2 hours.

The composition of the fluorinated copolymer 4 is such that TFE-based polymer units / E-based polymer units / CH ₂ ═CH (C
The molar ratio of F ₂ ) ₂ F based polymerized units is 53.0 / 4.
It was 1.3 / 5.7. The melting point was 207 ° C. and 257 ° C., the MFR was 59.2 g / 10 min, the MIT bending number was 55,000, and the number of carbonate end groups derived from the polymerization initiator was 560. 8.6X + 120
= 629> 560, and the fluorinated copolymer 4 did not satisfy the relationship of the formula (1).

Granules 4 were heated at 260 ° C. using an extruder.
Pellets 4 were prepared by melt-kneading with a residence time of 2 minutes.

The cylinder forming the outer layer is fed with the polyamide 12 of Example 1, the cylinder forming the intermediate layer is fed with the pellet 4 and the cylinder forming the inner layer is fed with the pellet 1 of Example 1, each of which is transported by cylinder. Transferred to the zone. The heating temperature in the transport zone for polyamide 12, pellets 4, and pellets 1 is 240 ° C, 260 ° C, respectively.
The temperature was 290 ° C. The temperature of the co-die was set to 260 ° C. and three-layer coextrusion was performed to obtain a three-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 outer layer of polyamide 12, the intermediate layer of fluorine-containing copolymer 4, and the inner layer of conductive fluorine-containing copolymer 1b were each 0.7 mm, It was 0.1 mm and 0.2 mm.

The peel strength between the layers of the obtained tube was measured. The inner layer and the intermediate layer could not be peeled off, and the material was partially broken to show high adhesion. The peel strength between the middle layer and the outer layer is 4
It was 9 N / cm. In this comparative example, the obtained fluoropolymer is excellent in adhesiveness, but compared with Example 2, MIT
The number of folds was low and the crack resistance was not sufficient.

[0063]

The fluorine-containing polymer of the present invention has excellent mechanical properties such as crack resistance because the MFR and the number of terminal groups derived from the polymerization initiator have the relationship of the formula (1). Excellent adhesion to other materials. In particular, it has excellent adhesion to polyamide. The fluoropolymer of the present invention is a polymerization initiator,
The polymerization pressure is 0.2 to 0.8 MPa in the presence of the polymerization medium.
And can be produced by polymerizing a fluorinated olefin.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J100 AA02Q AA03Q AA04Q AC22P                       AC23P AC24P AC25P AC26P                       AC27P AC31P AE38Q AE39Q                       BA15Q BA16Q BA19Q BB12Q                       CA01 CA04 CA05 CA27 DA43                       FA03 FA19 FA29 JA00

Claims (4)

[Claims] 1. A fluoropolymer characterized in that the melt flow rate of the fluoropolymer and the number of terminal groups derived from a polymerization initiator have the relationship of the following formula (1). Y> 8.6X + 120 (1) Here, Y is the number of terminal groups derived from the polymerization initiator for 10 ⁶ carbons in the fluoropolymer, which is 200 to 2000.
X is a melt flow rate at a temperature 50 ° C. higher than the melting point of the fluoropolymer under a load of 5 kg.
~ 200 g / 10 min. 2. The fluoropolymer according to claim 1, which contains a polymer unit based on tetrafluoroethylene, a polymer unit based on ethylene, and a polymer unit based on a monomer copolymerizable with tetrafluoroethylene and ethylene. 3. The method for producing a fluoropolymer according to claim 1 or 2, wherein the fluorinated olefin is polymerized in the presence of a polymerization initiator and a polymerization medium.
It is 8 MPa, The manufacturing method of the fluorine-containing polymer characterized by the above-mentioned. 4. The terminal group derived from the polymerization initiator is one or more selected from the group consisting of an ester group, a carboxylic acid group, a carbonate group, an amino group and a cyano group. Fluoropolymer.