JPH0741522A - Ethylene/tetrafluoroethylene copolymer - Google Patents

Abstract

PURPOSE:To provide an ethylene/tetrafluoroethylene copolymer which has a reduced modulus in flexure, has a large difference between its melting point and decomposition temp., and is improved in light transmittance and moldability by polymerizing tetrafluoroethylene with ethylene and a fluorinated vinyl monomer copolymerizable therewith. CONSTITUTION:A monomer mixture comprising 50-60mol% tetrafluoroethylene, 50-40mol% ethylene, and 2-7mol% fluorinated vinyl monomer copolymerizable therewith is suspension-polymerized in the presence of a polymerization initiator comprising an organic peroxide in a solvent mixture comprising a fluorine compound and water in a volume ratio of 9:1 to 1:9. Thus, the objective copolymer is obtained which has a volumetric flow rate of 10-300mm<3>/sec, a light transmittance of 85% or higher, a melting point of 230 deg.C or lower, and a bending modulus of elasticity of 7.0X10<3>kg/cm<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel ethylene / tetrafluoroethylene copolymer (hereinafter referred to as ETFE copolymer), more specifically, a novel ETFE copolymer characterized by low melting point, high transparency and flexibility. Regarding polymers.

[0002]

2. Description of the Related Art Conventional ETFE copolymers are known to have excellent cut-through resistance, melt processability, chemical resistance, electrical properties and the like. Firstly, it is widely used for various linings, chemical pump parts, etc. Furthermore, in recent years, the use as a protective film for organic materials has been rapidly growing due to its high transparency and weather resistance when thinned.

In recent years, users' demands for ETFE copolymers have been extremely widespread, such as enhancement of material properties for improving commercial value and possibility of long-term continuous molding for reducing running cost. . For electric wire / tube applications, flexibility is required so that it can handle more complicated wiring / piping and places with intense movement. Also,
In the application of a weather resistant protective film, higher transparency is required in order to make the substrate to be protected look more vivid and to obtain a higher amount of light in agricultural houses and the like. On the other hand, as a problem of the conventional ETFE copolymer, it has been pointed out that when it is operated for a long time at the time of molding, coloring due to decomposition or generation of tar due to a resin deterioration product is caused. A material having a high decomposition temperature, in other words, having a larger difference between the molding temperature and the decomposition temperature is desired.

In addition to the above requirements, ET
The chemical resistance, electrical properties and mechanical properties of the FE copolymer must be maintained, and it is impossible for the conventional ETFE copolymer to satisfy all such properties.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a novel ETFE copolymer having a low flexural modulus and a high light transmittance, a large difference between a melting point and a decomposition temperature, and improved moldability. To aim.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors can achieve the object by limiting the composition of the ETFE copolymer to a specific range. I found a thing.

That is, the present invention contains tetrafluoroethylene (hereinafter referred to as TFE), ethylene (hereinafter referred to as E) and a fluorine-containing vinyl monomer copolymerizable therewith, and the molar ratio of TFE / E is 50 to 60/50. ~ 40
And the content of the fluorine-containing vinyl monomer is 2 to 7 mol%, and the volume flow rate defined below is 10 to 300 m.
Provided is a novel ETFE copolymer characterized by having m ³ / sec.

When the content molar ratio of TFE / E in the ETFE copolymer is lower than 50/50, the decomposition temperature is lowered together with the melting point and the moldability is impaired. On the other hand, the content molar ratio is 60
When it is higher than / 40, lowering of melting point and softening are achieved, but transparency is impaired. Furthermore, the TFE / E content molar ratio of the copolymer is 60/4 because of the high alternating copolymerizability of E and TFE.
In order to make it more than 0, the reaction molar ratio of TFE / E in the reactor must be made more than 90/10, and as a result, there is a possibility that a polytetrafluoroethylene homopolymer is produced, which causes fish eyes. It is not preferable in manufacturing. Therefore, in order to have a low melting point, high transparency, flexibility and decomposition temperature characteristics, the TFE / E content molar ratio of the ETFE copolymer must be 50 to 60/50 to 40, and particularly excellent physical properties are required. In order to show, it is preferable to set it as 55-60 / 45-40.

[0009] fluorine-containing vinyl monomer used in the present invention, TFE and E and copolymerizable monomers, for example, CF ₂ = CFCl, fluoro ethylenes such as _{CF 2 = CH 2, CF 2} = CFCF 3, CF 2 = Fluoropropylenes such as CHCF ₃ , CH ₂ ═CHC ₂ F ₅ , CH
₂ = CHC ₄ F ₉ , CH ₂ = CFC ₄ F ₉ , CH ₂ = C
F (CF _{2) 3} H fluoroalkyl ethylenes number of 2 to 10 carbon atoms in the fluoroalkyl group, such as, CF ₂ = CF
O (CF ₂ CFXO) _m R _f (wherein R _f has 1 to 6 carbon atoms)
Is a perfluoroalkyl group, X is a fluorine atom or a trifluoromethyl group, and m is an integer of 1 to 5. ) And other perfluorovinyl ethers, CF ₂ = CFOCF ₂
CF ₂ CF ₂ COOCH ₃ or CF ₂ = CFOCF ₂ CF
Examples thereof include vinyl ethers having a group such as (CF ₃ ) OCF ₂ CF ₂ SO ₂ F which can be easily converted into a carboxylic acid group or a sulfonic acid group.

Among such fluorine-containing vinyl monomers, the formula CH ₂ ═CH—C _n F _{2n + 1} (provided in the formula: n is an integer of 2 to 10) and fluoroalkyl ethylene is selected, and in particular CH ₂ ═CH—C ₄
F ₉ is preferred. When the content of the fluorine-containing vinyl monomer is less than 2 mol%, it is difficult to achieve a low melting point and softening, and when it is more than 7 mol%, the polymerization rate becomes slow and productivity is lowered. 2) because the high strength at high temperature and the creep resistance of the ETFE copolymer are deteriorated.
7 mol%, especially 2.5 to 5.0 mol% is preferable.

In the present invention, as a polymerization method, a method conventionally used for polymerization of an ETFE copolymer, for example, bulk, solution, suspension, emulsion or gas phase polymerization can be adopted.

Considering industrial productivity, it is recommended to use a fluorine-based solvent.
An aqueous medium that uses an organic peroxide as a polymerization initiator
Suspension polymerization in the body is preferred. C as a fluorine-based solvent
Cl₂ F₂ , CCl₃ F, CClF₃ , CCl₂ FCC
IF₂ , CClF₂ CClF₂ Such as chlorofluoroca
Carbons, 1,1,2,2-tetrafluorocyclobutane
CF₂ HCF₂ CF₂ H, CF₃ CFHCF₂ CF
₂ CF₃ , CF₃ CF ₂ CF₂ CF₂ CF₂ H, CF₃ 
CF₂ CFHCF₂ CF₃ , CF₃ CFHCFHCF₂ 
CF₃ , CF₂ HCF₂ CF₂ CF₂ CF₂ H, CF₂ 
HCF HCF₂CF₂ CF₃ , CF₃ CF₂ CF₂ CF₂
 CF₂ CF₂ H, CF₃ CH (CF₃) CF₂ CF₂ C
F₃ , CF₃ CF (CF₃ ) CFHCF₂ CF₃ , CF
₃ CF (CF₃ ) CFHCFHCF₃ , CF₃ CH (C
F₃ ) CFHCF₂ CF₃ , CF₂ HCF₂ CF₂ CF
₂ CF₂ CF₂ H, CF₃ CF₂ CF₂ CF₂ CH₂ C
H₃ Hydrofluorocarbons such as CF_Four , CF
₃ CF₃ , CF₃ CF₂CF₂ CF₃ , CF₃ CF₂ C
F₂ CF₂ CF₂ CF₃ Such as perfluorocarbon
Kind, CF₃ CHFCF₂ OCH₂ CF₃ , CF₃ CF₂ 
CF₂ CF₂ OCF₃ , CF₃ (CF₂ )₂ O (CF
₂ )₂ CF₃ Fluorinated ethers such as
It

The mixing ratio (volume ratio) of the fluorine-based solvent and water is 9: 1 to 1: 9, and particularly 7: 7 from the viewpoint of suspension dispersibility and productivity.
It is preferably 3 to 3: 7.

As the organic peroxide used as the polymerization initiator, it is advantageous to use a peroxyester type radical initiator in terms of reaction operation, polymerization rate, various physical properties of the produced copolymer and the like. For example, t-butylperoxyisobutyrate, t-butylperoxyacetate, t-butylperoxypivalate, t-butylperoxy-2-ethylhexanoate, t-butylperoxylaurate, perfluorobutyryl. Examples thereof include luperoxide.

As the molecular weight modifier, it is possible to use usual ones such as n-hexane, methanol, carbon tetrachloride and methylene chloride, but it is particularly preferable to use an aliphatic alcohol having 1 to 3 carbon atoms. By using such a specific molecular weight modifier, it is possible to control to a desired molecular weight,
In addition, the produced copolymer is improved in coloring, heat aging resistance and the like. As such a molecular weight regulator, ROH (R
Is a methyl group, an ethyl group or a propyl group) 1
Primary alcohols are preferable, and methyl alcohol is particularly preferable. The amount of the molecular weight modifier used is appropriately determined depending on the required molecular weight, the amount of the polymerization initiator used, the monomer concentration, and the like.

[0016]

EXAMPLES Examples of the present invention will now be described more specifically, but the present invention is not limited to the examples. In the following examples, the physical properties of the copolymer were measured by the following methods.

Volumetric flow rate (Q value): diameter of 1 m under a load of 30 kg / cm ^{2 at} 300 ° C. using a Koka type flow tester
The volume (mm ³ / sec) of the copolymer flowing out from a nozzle of m and a length of 2 mm per unit time was measured. Polymer composition: determined from ¹⁹ F-NMR and elemental analysis. Melting point: The melting peak (maximum value) when the temperature was raised at a rate of 10 ° C./min using a Perkin Elmer 7 differential scanning calorimeter device was taken as the melting point. Decomposition temperature: The point at which 10% weight loss occurred when the temperature was raised at a rate of 10 ° C./min using a vacuum Riko TGD7000 high-speed differential thermal balance apparatus was defined as the decomposition temperature. Tensile strength / elongation: Performed using a V-shaped dumbbell according to ASTM-D638. Flexural modulus: measured according to ASTM-D790. Light transmittance: The transmittance at 400 nm of a film having a thickness of 60 μm was measured with an ultraviolet-visible spectrophotometer.

Example 1 In a stainless steel autoclave having an internal volume of 10 liters, 200 g of methanol and trichlorotrifluoroethane (hereinafter referred to as R-113) 328
6 g, deoxygenated water 4900 g, TFE 634 g, E
25 g, and perfluorobutyl ethylene (hereinafter P
46g was charged. The reaction temperature was maintained at 65 ° C. with thorough stirring of this mixture. Next, 50% by weight of the initiator t-butylperoxyisobutyrate R-
Polymerization was initiated by adding 29 ml of the 113 solution.
According to the pressure drop during the reaction, a mixed gas having a molar ratio of TFE / E / PFBE of 57/40/3 was introduced into the system to give a polymerization pressure of 1
4 kg / cm ² G was maintained. 882g in 7.25 hours
A white copolymer of The copolymer has a volume flow rate (Q value)
= 105 (mm ³ / sec), copolymer composition TFE / E
/ PFBE = 57/40/3 (mol%), melting point 229
℃, decomposition temperature 410 ℃, flexural modulus 6.5 × 10 ³ kg
/ Cm ² , and the light transmittance was 88.7%.

[Example 2] In Example 1, the initial charging amount was 150 g of methanol, 577 g of TFE, and 40 of E.
g, perfluorooctylethylene (hereinafter referred to as PFOE) 94 g, and the molar ratio of the post-charged mixed gas is TFE / E.
The same operation was repeated except that / PFOE = 51/45/4, and 920 g of a white copolymer was obtained in 8 hours. The copolymer has a volume flow rate of 63 (mm ³ / sec), a copolymer composition TFE / E / PFOE = 51/45/4 (mol%),
Melting point 220 ° C, decomposition temperature 401 ° C, flexural modulus 6.2 ×
The light transmittance was 10 ³ kg / cm ² , and the light transmittance was 89.4%.

[Embodiment 3] In Embodiment 1, the initial charging amount is set to 30 of CH ₃ CH ₂ C ₄ F ₉ instead of R-113.
In addition to 65g, 170g of methanol, 52 of TFE
8 g, 21 g of E and 41 g of PFBE, and the post-mixture mixed gas is in a molar ratio of TFE / E / PFBE = 58.1 / 3.
Repeat the same operation except set to 8.8 / 3.1, and
Over a period of time, 990 g of a white copolymer was obtained. The copolymer had a volume flow rate of 71 (mm ³ / sec) and a copolymer composition of TFE / E.
/PFBE=58.1/38.8/3.1 (mol%),
Melting point 223 ° C, decomposition temperature 411 ° C, flexural modulus 6.3 ×
The light transmittance was 10 ³ kg / cm ² , and the light transmittance was 88.9%.

[Embodiment 4] In Embodiment 1, the initial charging amount is changed to CF ₃ CF ₂ CF ₂ CF ₂ C instead of R-113.
In addition to 3258 g of F ₂ CF ₂ H, methanol 18
0g, TFE 532g, E 22g, PFBE 46
g, and the post-charge mixed gas in a molar ratio of TFE / E / PFB
The same operation was repeated except that E = 55.8 / 40.4 / 3.8, and 975 g of a white copolymer was obtained in 7 hours.
The copolymer had a volume flow rate of 110 (mm ³ sec) and a copolymer composition of TFE / E / PFBE = 55.8 / 40.4 /
3.8 (mol%), melting point 221 ° C., decomposition temperature 409 ° C.,
Flexural modulus 6.1 × 10 ³ kg / cm ² , light transmittance 8
It was 9.2%.

[Embodiment 5] In Embodiment 1, the initial charge is CF ₃ CF ₂ CF ₂ CF ₂ C instead of R-113.
F ₂ CF ₃ 3528 g, methanol 150
g, TFE of 540, E of 22 g and PFBE of 33 g, and the post-mixture mixed gas in a molar ratio of TFE / E / PFBE =
The same operation was repeated except that the amount was 58.5 / 39.0 / 2.5 to obtain 1005 g of a white copolymer in 7 hours. The volumetric flow rate of the copolymer was 69 (mm ³ / sec), the copolymer composition was TFE / E / PFBE = 58.5 / 39.0 / 2.
5 (mol%), melting point 227 ° C., decomposition temperature 415 ° C., flexural modulus 6.4 × 10 ³ kg / cm ² , light transmittance 88.
It was 4%.

[0023] In Example 6 Example _{5, CF 3 CF (CF 3} ) instead of the initially charged amount _{CF 3 CF 2 CF 2 CF 2} CF 2 CF 3 CFHCFHCF 3 and 3444G, moles of post-charged gas mixture TFE / E / PFBE =
The same operation was repeated except that the ratio was changed to 57.3 / 39.9 / 2.8 to obtain 986 g of a white copolymer in 7 hours. The copolymer had a volume flow rate of 79 (mm ³ / sec) and a copolymer composition of TFE / E / PFBE = 57.3 / 39.9 / 2.8.
(Mol%), melting point 225 ° C., decomposition temperature 411 ° C., flexural modulus 6.2 × 10 ³ kg / cm ² , light transmittance 88.6.
%Met.

[0024] In Example 7 Example 5, and CF ₃ CFHCFHCF ₂ CF ₃ 3516g initial charged amount in place of _{CF 3 CF 2 CF 2 CF 2} CF 2 CF 3, TFE rear feed gas mixture in a molar ratio /E/PFBE=57.9
The same operation was repeated except that the ratio was set to /39.4/2.7, and 990 g of a white copolymer was obtained in 7 hours. The copolymer has a volume flow rate of 83 (mm ³ / sec) and a copolymer composition of TF.
E / E / PFBE = 57.9 / 39.4 / 2.7 (mol%), melting point 226 ° C., decomposition temperature 410 ° C., bending elastic modulus 6.2 × 10 ³ kg / cm ² , light transmittance 88. It was 6%.

Comparative Example 1 Using the same autoclave as in Example 1, trichloromonofluoromethane 3867 was used.
g, R-113 6456g, TFE 1153g, E
Of 55.8 g and PFBE of 50.2 g were charged.
The reaction temperature was maintained at 65 ° C. with thorough stirring of this mixture. Next, 15 ml of a 50 wt% R-113 solution of t-butylperoxyisobutyrate as an initiator was added to initiate polymerization. Depending on the pressure drop during the reaction, the molar ratio of TFE / E / PFBE is 52.8 / 45.8 in the system.
Polymerization pressure 13.4 kg /
cm ² G was held. 890 g of a white copolymer was obtained in 8.1 hours. The copolymer has a volume flow rate of 75 (mm ³ / se
c), copolymer composition TFE / E / PFBE = 52.8 /
The melting point was 45.8 / 1.4 (mol%), the melting point was 265 ° C., the decomposition temperature was 390 ° C., the flexural modulus was 9.5 × 10 ³ kg / cm ² , and the light transmittance was 82.1%.

[Comparative Example 2] In Example 1, the initial charging amount was 150 g of methanol, 700 g of TFE, and 5.
6 g, PFBE 36.9 g, the same operation was repeated except that the molar ratio of the post-charged mixed gas was TFE / E / PFBE = 64/34/2, and the white copolymer 920 was obtained in 8 hours.
g was obtained. The copolymer has a volume flow rate of 95 (mm ³ / se
c), copolymer composition TFE / E / PFOE = 64/34
/ 2 (mol%), melting point 224 ° C., decomposition temperature 407 ° C., flexural modulus 5.0 × 10 ³ kg / cm ² , light transmittance 7
It was 9.7%.

The results of Examples 1, 2, 3, 4, 5, 6, 7 and Comparative Examples 1 and 2 are shown in Table 1.

[0028]

[Table 1]

From these results, it is clear that when the compositional range of the present invention is not satisfied, the melting point and the softening are not achieved in Comparative Example 1, and the transparency and the tensile strength are decreased in Comparative Example 2. Is.

[0030]

According to the present invention, it is possible to obtain a novel ETFE copolymer having improved moldability by lowering the melting point and improved flexibility and transparency while maintaining the properties of the conventional ETFE copolymer. You can

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yukio Minoru Yukio Kirisaki 1150 Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Central Research Laboratory, Asahi Glass Co., Ltd. (72) Masanori Kaya 1150, Hazawa-machi, Kanagawa-ku, Yokohama (72) Inventor Haruhisa Miyake 1150 Hazawa-machi, Kanagawa-ku, Yokohama, Kanagawa Prefecture Asahi Glass Co., Ltd.

Claims (8)

[Claims] 1. A method comprising tetrafluoroethylene, ethylene and a fluorine-containing vinyl monomer copolymerizable therewith,
Tetrafluoroethylene / ethylene content molar ratio is 50
A 60/50 to 40, the content of the fluorine-containing vinyl monomer is 2 to 7 mol%, ethylene / tetra volume flow rate, as defined herein is characterized by a 10 to 300 mm ³ / sec Fluoroethylene copolymer. 2. A fluorine-containing vinyl monomer has the formula CH ₂ ═CH.
The ethylene / tetrafluoroethylene-based copolymer according to claim 1, which is an alkylethylene represented by —C _n F _{2n + 1} (where n is an integer of 2 to 10). 3. The fluorine-containing vinyl monomer is CH ₂ ═CH—
The ethylene / tetrafluoroethylene copolymer according to claim 1, which is C ₄ F ₉ . 4. The content of fluorine-containing vinyl monomer is 2.5.
The ethylene / tetrafluoroethylene-based copolymer according to claim 1, which is ˜5.0 mol%. 5. The ethylene / tetrafluoroethylene copolymer according to claim 1, which is obtained by copolymerizing tetrafluoroethylene and ethylene using an aliphatic alcohol having 1 to 3 carbon atoms as a molecular weight modifier. 6. The ethylene / tetrafluoroethylene copolymer according to claim 1, which has a light transmittance of 85% or more as defined in the text. 7. The ethylene / tetrafluoroethylene copolymer according to claim 1, which has a melting point of 230 ° C. or lower. 8. A flexural modulus of 7.0 × 10 ³ kg / cm ²
The ethylene / tetrafluoroethylene-based copolymer according to claim 1, which is: