DE2125928C3 - Process for the preparation of a copolymer from tetrafluoroethylene and propylene - Google Patents

Description

The invention relates to a method for producing difficult to obtain a copolymer with a high Moieku-

to achieve a copolymer of tetrafluoroethylene and propylene largewise and the molecular weight of the

controlled by copolymerization of tetrafluoroethylene and copolymers. In addition, it is

Propylene under irradiation with ionizing high difficult, a copolymer of tetrafluoroethylene and

energy rays. 40 to produce propylene, which has suitable crosslinking

It is known that copolymers of tetrafluoroethylene have properties. The copolymers of tetra and propylene by suspension copolymerization fluoroethylene and propylene according to the USA patent of tetrafluoroethylene and propylene in the presence of 3,467,635 has z. B. to produce a tensile strength of only 60 kg / of an organic peroxide catalyst, cm ² , even if the copolymer is crosslinked. It is as disclosed in British Patent Specification 594,249. 45 therefore not suitable for industrial purposes.
Furthermore, it is known, this copolymer by Thus it is the object of the invention to provide a method of emulsion copolymerization of Tetrafiuoräthylen for the production of a copolymer of Tetrafiuor- and propylene in the presence of a water-soluble ethylene and propylene, which produce with a catalyst, as in the U.S. Patent High enough rate of copolymerization document 3,467,635 disclosed. However, these known processes, and if necessary run at a relatively low pressure, have the disadvantage that they require a pressure which is very high with a reduced polymerization reaction, which takes place in approximately the gas phase and is 150 kg / cm ^a for a pure copolymer. This makes complicated and of Tetrafiuoräthylen and Propylen with a heavy device necessary. Furthermore, with this controlled high molecular weight it is possible to convert a crosslinked copolymer with excellent formation of a catalyst only to obtain strength wedge properties in conventional processes,
of a copolymer with a relatively low mole- This object is achieved according to the invention by a number of up to 60,000. Furthermore, it is in the solves that the irradiation in an aqueous medium conventional emulsion copolymerization process and in the presence of a perfluorinated or a perfahren necessary, a buffer and other additives fluorochlorinated dispersant is carried out to mix into the reaction system to obtain the activity The molar ratio of tetrafluoroethylene and the polymerization initiator. This buffer propylene can be selected within a wide range and the other additives tend to be selected. For example, good results will remain in resulting copolymers. It is achieved when the molar ratio of tetrafluorine is very difficult to completely remove it by washing it out to 65 ethylene to propylene at 99: 1 to 1:99, preferably, and they affect the otherwise high 95: 5 to 30:70 and especially 95 : 5 to 50:50, remarkable heat resistance properties of the course depends on the degree of polymerization and the copolymers of tetrafluoroethylene and propylene. special composition of the copolymer of

the intermittent molar proportions of tetrafluoroethylene and propylene. If higher concentrations of tetrafluoroethylene are used, the resulting copolymer "!" is observed, and the copolymerization reaction rate is satisfactory. From the standpoint of reducing the polymerization reaction in the gas phase, it is not desirable to select a high molar proportion of tetraluminous ethylene.

It is possible to "polymerize" another suitable comonomer, as far as the advantages of the combination are concerned of tetrafluoroethylene and propylene are not lost in the process according to the invention. For example, it is possible to use tetrafluoroethylene, propylene and a small amount of a comonomer, such as ethylene, isobutylene, or fluoro-olefins copolymerize. It is also possible to use tetrafluoroethylene, Propylene and a small amount of a comonomer which causes crosslinking, such as. B. Acrylic acid or chloroethyl vinyl ether to copolymer »Ieren, if crosslinkable copolymers of tetrafluorithylene and propylene are desirable.

The dispersant used in the present invention «Is suitable for emulsifying tetrafluoroethylene And propylene and has no inhibitory effect on the copolymerization reaction. Typical dispersants of this type are water-soluble salts of aliphatic perfluorocarboxylic acids and aliphatic perfluorocarboxylic acids as well as water-soluble compounds of phosphoric acid esters of an aliphatic perfluoro alcohol as well as perfluorosulfates and perfluorochlorine »Sulphates. The perfiuorierlen used according to the invention or perfluoro "hlorie.; s emulsifiers show no inhibitory effect in relation to the copolymerization reaction.

The amount of dispersant used in the process of the present invention is usually 0.0001 to 10, in particular 0.001 to 5 percent by weight, based on the aqueous medium.

Any high energy ionizing radiation can be used to effect the copolymerization reaction. The irradiation can 7. B. with y-rays. X-rays, -rays, ^ -rays or electron rays can be carried out. Any type of sirradiation source for irradiation with ionizing rays can be used, such as e.g. B. a radioactive element, such as cobalt 60 and cesium 137. Furthermore, the irradiation can be carried out with the aid of an atomic reactor, an IR-X-ray generator and a particle accelerator.

In general, y-rays originating from a cobalt-60 source are preferred. The intensity of the irradiation with ionizing rays can be between 10 ^J and 10 ⁷ X-rays per hour and preferably between 10 ³ and 10 "X-rays per hour. When a high radiation intensity is used, the rate of the copolymerization reaction is generally high, the molecular weight of the However, if the total radiation dose is too low, the conversion of the monomers into the copolymer is reduced, whereby the yield of the copolymer is reduced. Accordingly, it is preferred to use a total radiation dose of 10 ² to TO ⁸ X-rays, and in particular 10 ³ to be used up to 5 x 10 'X-rays.

If desired, various additives can be used in accordance with conventional emulsion polymerization can be applied. Such additives include stabilizers, such as. B. trifluorotrichloroethane, t-butanol, chlorinated hydrocarbons, liquid hydrocarbons; water-soluble reaction starters, such as. B. ammonium pereulfate, potassium persulfate and azo compounds. However, it is entirely possible to completely eliminate these additives, which contaminate the copolymer obtained according to the invention.

The temperature of the copolymerization reaction is not critical. The reaction may preferably be conducted for 5 to 8O ⁰ C in a temperature range of 0 to 100 ⁰ C and. The reaction pressure can be lower than that of conventional methods.

Good results are achieved when the pressure is below 100 kg / cm *, preferably at 1 to 50 kg / cm * lies. According to the invention, the emulsion copolymerization can advantageously without the use of a high reaction pressure can be carried out. However, it is entirely possible to carry out the copolymerization itself at very high pressure or at very low pressure. The inventive method can be carried out in continuous operation or in batch operation.

According to the invention, a copolymer of tetrafluoroethylene and propylene can be prepared which has a sufficiently high molecular weight to be excellent after crosslinking of the copolymer Properties to deliver. The particular desired specific copolymer can easily be obtained, by measuring the radiation dose with ionizing radioactive syrups, the reaction temperature and selects the reaction pressure. The use of a molecular weight regulator or application a high reaction pressure is not required.

According to the invention, it is possible to produce copolymers of tetrafluoroethylene and propylene which have a molecular weight of more than 60,000 and in particular a molecular weight of 70GCO to 100,000. The copolymer produced according to the invention can be crosslinked in the most varied of ways in order to obtain a crosslinked copolymer with a tensile strength of about 100 kg / cm ¹ . With the process according to the invention, the copolymer of tetrafluoroethylene and propylene can be obtained in the form of a latex dispersion of the copolymer in an aqueous medium. The copolymers exhibiting elastic properties can be separated from the aqueous medium by known conventional methods, the copolymer coagulating from the latex. The separated copolymer can by means of a crosslinking agent, such as. B. od by means of an organic peroxide or a polyvalent amine. Like. Are crosslinked, resulting in a rubber-like product. It is also possible, the inventive copolymer by irradiation with ionizing radioactive rays, such as. B. od with y-rays, electron rays. Like. To network. In the latter case, the copolymer can be partially crosslinked by irradiating it with the appropriate dose of ionizing radioactive rays. This irradiation can be carried out on the latex without separating the copolymer.

The copolymer of tetrafluoroethylene and propylene produced by the process according to the invention can thus be converted into a crosslinked copolymer which is excellent

has mechanical strength and other properties that cannot be achieved with conventional methods can be achieved.

In the following, the invention is explained in more detail on the basis of exemplary embodiments. δ

example 1

200 g of oxygen-free water and 0.40 g of the ammonium salt of perflunroctanoic acid are placed in a stainless steel autoclave which has a capacity of 500 ml. The air is removed by repeated solidification and evacuation and 25.0 g of tetrafluoroethylene and 5.25 g of propylene are added. The mixture is then ^{irradiated at 28 °} C. with stirring at 750 revolutions / minute with γ-rays from a cobalt 60 radiation source, an irradiation intensity of 3.3 · 10 ⁴ X-rays / h being selected for 16.8 hours. The pressure of the copolymerization reaction system is decreased ^{from 16 kg / cm 2} to 10 kg / cm ^2. After the copolymerization reaction, unreacted monomer is removed from the system, and the latex containing 5% of the copolymer of tetrafluoroethylene and propylene is taken out. The polymerization rate is 2.1% / h. The latex is frozen and coagulated, 101 g of gut-like elastomer being obtained which is soluble in tetrahydrofuran and in trichlorotrifluoroethane. The viscosity number of the copolymer in tetrahydrofuran ^{solution (100 cm a} / g at 30 ^° C. is 0.44.

Examples 2 to 4

10 g of oxygen-free water and 20 mg of the ammonium salt of perfluorocltanoic acid are in a Stainless steel autoclave with a capacity of 50 ml. The compiled in Table 1 Additions are added

The air is removed by repeated solidification and evacuation, and the monomers according to Table 1 are introduced under pressure. The mixture is then irradiated at room temperature with stirring for 10 hours with γ-rays from a cobalt 60 radiation source with a radiation intensity of 3.3 · 10 ⁴ X-rays / h. The results are compiled in the table.

Table !

additions Monomer
C ₂ F ₁ C ₃ H ⁵
(G) concentration
of latex Conversion to
the L3tex ,,. ι THF
^{1 / J} 30 C Example 2 CF..C1CCLF
2.0 g 2.53 0.53 3.3% 95% 0.41 Example 3 t-BuOH
2.0 g 2.38 0.50 4.6% 93% 0.54 Example 4 CF., C1CC1 ₂ F 2.99 0.12 19.6% 62% 0.82

Comparative example

The copolymer of tetrafluoroethylene and propylene according to example! 1 is crosslinked to give a crosslinked copolymer having the following properties: tensile strength 97 kg / cm ² ; Elongation 750%; Weight loss only about 5% when heated to 260 ° C. for 400 hours.

Example 5

10 g of oxygen-free water and 20 mg of the ammonium salt of Perfluorooctansaurc are in one. Given a stainless steel autoclave with a volume of 50 ml. The air is removed and 2.60 g of tetrafluoroethylene and 0.55 g of propylene are introduced under pressure. Irradiation with γ-rays from a Koball-60 radiation source with a radiation intensity of 3.3 · 10 ⁴ X-rays / h is then carried out at room temperature with stirring for 10 hours. As a result, 69% conversion is observed, and the resulting aqueous solution has 4% by weight of latex.

Example 6

The process according to Example 4 is repeated, but using t-BuOH _{instead of CF 2} ClCl _{2 F.} The emulsion polymerization under irradiation with γ-rays leads to a conversion. tion to the latex of 69%, and it becomes an aqueous solution with 6% by weight of I. "". er. Receive.

Example 7

2 liters of oxygen-free water and 60 g of the ammonium salt of perfluorooctanoic acid are placed in a stainless steel autoclave given with 51 volume. The air becomes through repeated solidification and evacuation removed and 1450 grams of tetrafluoroethylene and 207 grams of propylene are added.

The mixture is then irradiated at 25 ° C. with stirring for 10 hours with γ-rays from a K.obalt 60 radiation source at an irradiation intensity of 3.3 · 10 ⁴ X-rays / h. The pressure of the copolymerization reaction system is 28 to 30 kg / cm ² . There are 370 g of the copolymer of Tetrafluoräthylcn and P-opylcn with a Viskositälszahl in tetrahydrofuran solution at 30 ^c C of 0.67 obtained. The molecular weight of the copolymer is 78,000.

60

65

Example 8

The emulsion copolymerization according to Example 7 is repeated, but irradiation with γ-rays at 2 · 10 ⁴ X-rays / h is carried out. The copolymer of tetrafluoroethylene and propylene has a viscosity number of 0.77 ^{in tetrahydrofuran solution at 30 ° C.} It has a molecular weight of 90,000.

Example 9

2 liters of hydrogen-free water and 10 g of the ammonium salt of fluorooctanoic acid are placed in a stainless steel autoclave with a volume of 5 liters. A mixture of tetrafluoroethylene and propylene with a molar ratio Tl'KTP of 85:15 is added continuously so that a pressure of 25 kg'cm ^{2 is} maintained. Then at 25 ° C. with stirring for 20 hours, irradiation with ^ 'rays from a cobalt-60 radiation source with a radiation intensity of 5 · 10' Rönlgcn / h is irradiated. 170 g of the copolymer of tetrafluoroethylene and propylene which has a viscosity number of 0.65 in tetrahydrofuran at 30 ° C. are obtained. The molecular weight of the copolymer is 74,000.

Example 10

Tetrafluoroethylene and propylene are in the presence of 3.0 percent by weight of an aqueous solution of the ammonium salt of fluorooctanoic acid (the oxygen has been removed) in a 25 ml ampoule polymerized. The molar ratio of tetrafluoroethylene to propylene is 75:25. The irradiation is at 5'C with stirring with a ^ radiation intensity of 5 · 10 'X /' h with - / - rays of a cobalt 60 radiation source accomplished. The obtained copolymer of tetrafluoroethylene and propylene has a Viscosity number in tetrahydrofuran of 0.65. The molecular weight of the copolymer is 74,000.

Comparative example

A mixture of 100 parts by weight of the copolymer of tetrafluoroethylene and propylene and 25 parts by weight of F-Kf-'carbon (manufactured by Tokai Denkyoku Co. Ltd.). is irradiated by means of a cobalt-60 radiation source with 15Mrad j'-rays. A crosslinked copolymer is obtained in this way. This has a tensile strength of 158 kg / cm ² and a clong galion of -63 "".

Comparative example

The copolymer of tetrafluoroethylene and propylene gcmiili Example 7 is in the following formulation pressure vulcanization at 160 ° C. for M) minutes.

Formulation:

Copolymer 100

MgO '. 5

FKF carbon slipper 25

Peroxide 4

Triallyl cyanurate 3

It becomes a \ crnctzlcs copolymer with a train

strength of 120 kg / cm ⁵ and with a cloning ratio of 370 ",, obtained. If the obtained crosslinked!

Copolymers is heated to 160 ° C. for 20 hours, the tensile strength increases to 150 kg / cm ²

Claims (6)

1 2 It is also known to produce copolymers from Tetrafluar claims: ethylene and propylene under irradiation with ionizing the high-energy rays (see Kogyo 1. Process for the production of a copolymer Kagaku Zasshi 68 [iO] 1926-9), a pure one of tetrafluoroethylene and propylene being obtained by copolymers. However, this process had the disadvantage that the merisatiort of tetrafluoroethylene and propylene had the disadvantage that the rate of polymerization under irradiation with high-energy ionizing radiation was very low and was approximately in the range of 0.1% / h, characterized in that another disadvantage was the low polymer that the irradiation in an aqueous medium sationsgrad. Furthermore, it is difficult to dissipate the heat of reaction with this and in the presence of a perfluorinated or a io drive, so that it carried out perfluorochlorinated dispersant is not suitable for industrial purposes. will. It is known that various fluoroolefins such as 2. The method according to claim 1, characterized in z. B. tetrafluoroethylene, trifluorochloroethylene and draws that the molar ratio of tetra-hexafluoropropylene in an aqueous medium, welfluoräxhylen to propylene is 95: 5 to 50:50. 15 ches contains a dispersant, under irradiation 3. The method according to claim 1 or 2, characterized with ionizing high-energy beams of an emulsion, that the reaction pressure can be subjected to 1 to ion polymerization 50 kg / cm * (Japanese Patent Publication 24 "179/1967, Japanese Pa- 4. The method according to any one of claims 1 to 3, tentschrift 4866/1968 and Japanese patent, characterized in that the reaction tem- ao 12817/1968). In these conventional strahlungsperatur is 5 to 8O ⁰ C. induced emulsion polymerization process 5. The method according to any one of claims 1 to 4, a polymerization reaction easily occurs characterized in that the dispersant is in the gas phase, which gives unfavorable results, in an amount of 0.001 to 5 percent by weight, based on the prevention of such adverse poly on the aqueous medium, employed 25 merization reaction in the gas phase, it is necessary agile, the reaction system a hydrocarbon 6. The method according to any one of claims 1 to 5, add substance. This added hydrocarbon is characterized in that the radiation acts, however, usually as a radioactive transmitter, the intensity of ionizing rays ICi ³ to 10 "is reduced by the molecular weight of the polymer obtained X-ray / hour. 30. Furthermore, it is difficult to completely remove the hydrocarbon from the obtained polymers washed out, so that the heat resistance properties of the polymer obtained are lowered.
35 It is also with these conventional methods