DE2635402A1 - VULCANIZABLE PLASTIC FLUOROPOLYMERISATES - Google Patents

Description

The invention relates to copolymers which are vulcanizable plastic fluoropolymers.

Plastic fluoropolymers, e.g. polytetrafluoroethylene and tetrafluoroethylene / hexafluoropropylene copolymers, have high melting points, with the result that the polymers are difficult to process by known processes and are not easily vulcanizable with known crosslinking agents. There is a need for plastic fluoropolymers that have a combination of properties including good vulcanizability, Rigidity at low temperatures, processability at high temperatures, heat resistance and solvent resistance exhibit. In many applications a plastic fluoropolymer is needed that has processability at high temperatures and stiffness at low temperatures with the vulcanizability with cheap, readily available vulcanizing agents combined.

609886/1109

The invention relates to vulcanizable plastic fluoropolymers consisting essentially of the following Components consist of: ι

approximately
A) / 50 to 85% by weight of tetrafluoroethylene units,

B) about 10 to 45 wt .-% vinylidene fluoride units and

C) about 5 to 40% by weight of hexafluoropropylene units. ,

The invention further comprises vulcanizable plastic compositions which contain the above-mentioned plastic fluoropolymers, a crosslinking agent and optionally _; contain a vulcanization accelerator.

The copolymers according to the invention combine the desired properties of processability at high temperatures with rigidity at low temperatures. Since the copolymers large amounts of tetrafluoroethylene contain, they have a stiffness at low temperatures that is similar to that of plastics is comparable. However, since most plastics have relatively high melting points, must they are processed with special equipment. But since the copolymers according to the invention are vinylidene fluoride and hexafluoropropylene, they have a lower melting point than most fluoroplastics. This enables them to be processed using conventional processing machines. In addition, the presence allows of vinylidene fluoride and hexafluoropropylene the Vulkani— ■ sation of the plastic "copolymers by the same process that is used for the vulcanization of fluoroelastomers can be applied. The copolymers according to the invention can either be used in the unvulcanized state as thermoplastics or used as thermoset materials in the vulcanized state.

In some preferred embodiments of the invention, the plastic fluoropolymers consist of a) about 50 to 80% by weight of tetrafluoroethylene units, b) about '.

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15 to 40 wt .-% vinylidene fluoride units and c) from about \ 5 to 20 wt .-% of hexafluoropropylene.

j The plastic fluoropolymers according to the invention j can with the help of a dispersion or suspension; Polymerization reaction in which a catalyst which forms free radicals, for example an inorganic persulfate, has to be added. A fluorocarbon soap, for example ammonium perfluorooctanoate, can
be added in order to keep the polymer in suspension. After the polymerization reaction has ended
If the fluoropolymer has the form of dispersed particles which are isolated by agglomeration, filtration or centrifugation and subsequent drying.

can. [

ι During the production of the copolymers, the

Reaction mixture preferably to about 50 to "130 ° C i

under positive pressure, e.g. 7 to 140 kg / cm, preferably

2 about 35 to 105 kg / cm, heated. The polymerization

can be carried out batchwise or continuously

The preferred reaction mixture of monomer components; contains a free radical initiator, and
the copolymerization reaction is called free radical; Emulsion polymerization carried out. As free radical initiators are, for example ammonium persulfate, sodium, potassium and \ mixtures of two or more thereof.
Water-soluble inorganic per- 'are also suitable. oxide compounds, for example sodium, potassium and ammonium perphosphates, perborates and percarbonates. The Initia-

tor can be used in combination with a reducing agent, ■ e.g. sodium, potassium or ammonium sulfite, bisulfite, metabisulfite, hyposulfite, thiosulfate, phosphite or -hypophosphite, or in combination with an iron (II) -,

609886/1109 ome _(NAL

2-35402

Copper (I) - or silver salt or another easily oxidizable metal compound can be used. Well-known organic radical initiators can also! if used, preferably in combination with ¹ a suitable surface-active agents, for example sodium lauryl sulfate and ammonium perfluorooctanoate. .

Vulcanized mixtures can be prepared by mixing the fluoropolymers according to the invention with a suitable crosslinking agent and an Eeschleu niger and heating the mixtures until they are vulcanized. In preferred embodiments, the fluoropolymer also contains a metal compound consisting of a divalent metal oxide, for example magnesium oxide, zinc oxide, calcium oxide or lead oxide, a divalent metal hydroxide, a mixture of the oxide and hydroxide or a mixture of the oxide and / or hydroxide with a metal salt of a weak acid, for example a mixture which contains about 1 to 70% by weight of the metal salt, admixed. Examples of suitable metal salts of weak acids are barium, sodium, potassium, lead and calcium stearate, benzoate, carbonate, oxalate and phosphite. The metal compound is added in an amount of about 1 to 15 parts by weight, preferably 2 to 6 parts by weight, per 100 parts of fluoropolymer. The metal compound absorbs certain gaseous and acidic substances that are developed during vulcanization. '■

Mixtures according to the invention, which consists of a mixture of the plastic fluoropolymer and an aromatic Polyhydroxy compound or another suitable crosslinking agent are valuable commercial products, which (as in the case of a new polymer) 'works can be delivered after modification the composition with certain additives according to the requirements of certain applications

6 0 9 8 8 6/1109 originally inspected

5402

Manufacture plastic parts.

Any aromatic ι hydroxy compounds, diamines (preferably aliphatic | or alicyclic diamines) and diamine carbamates, their
Suitability for the vulcanization of fluoropolymers is known, can be used alone or in groups. | Aromatic hydroxy compounds suitable as crosslinking agents are selected from known aromatic polyhydroxy compounds which are known as crosslinking agents for known elastomeric copolymers. For example, the following crosslinking agents ^! are used: di-, tri- and tetrahydroxybenzenes,
-Naphthalenes and -Anthracenes as well as bisphenols of formula;

η (HO) (OH) _n

where A is a difunctional aliphatic, cycloaliphatic! tic or aromatic radical with 1 to 13 carbon atoms
or a thio group, an oxy group, a carbonyl group,
Sulfinyl group or sulfonyl group and optionally j is substituted by at least one chlorine atom or fluorine atom, χ is 0 or 1, η is 1 or 2 and
a any aromatic ring of the polyhydroxy compound is optionally substituted with at least one chlorine atom, -

Fluorine atom or bromine atom, a group of the formula -CHO

i or a carboxyl group or an acyl radical (e.g.:

a group of the formula -COR, in which R is OH or a C ^ -Cg -alkyl radical, -aryl radical or cycloalkyl radical)
is substituted. From the above formula of the bisphenol it can be seen that the -OH groups can be bonded in any position (apart from the 1-position) in both rings j. Mixtures of two or more
these compounds can also be used ·; Examples of specific compounds of this type are given

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in US Pat. No. 3,876,654 (e.g. column 4, line 62 to column 5, line 15). Preferred compounds include hexafluoroisopropylidene bis (4-hydroxybenzene). If the bisphenol of the above formula A is an alkylene radical, it can be, for example, methylene, | Ethylene, chloroethylene, fluoroethylene, difluoroethylene, 1,3-propylene, 1,2-propylene, tetramethylene, chlorotetramethylene, fluorotetramethylene, trifluorotetramethylene,; 2-methyl-1,3-propylene, 2-methyl-1,2-propylene, penta [ methylene, pentachloropentamethylene, pentafluoropentamethylene and hexamethylene. If A is an alkylidene radical, this radical can be, for example, ethylidene, dichloroethylidene, difluoroethylidene, propylidene, isopropylidene, trifluoroisopropylidene, hexafluoroisopropylidene, butylidene, heptachlorobutylidene, heptafluorobutylidene, pentylidene, hexloylidene and 1,1-cycloylidene. If A is a cycloalkylene radical, this radical can, for example, 1,4-cyclohexylene, 2-chloro-1,4-cyclohexylene, 2-fluoro-1,4-cyclohexylene, 1,3-cyclohexylene, cyclopentylene, chlorocyclopentylene, fluorocyclopentylene and cyclo- ^! be heptylene. Furthermore, A can be an arylene radical, for example n-phenylene, p-phenylene, 2-chloro-1,4-phenylene, 2-fluorine-! 1,4-phenylene, o-phenylene, methylphenylene, dimethylphenylene, trimethylphenylene, tetramethylphenylene, 1,4-naphthylene, 3-fluoro-1,4-naphthylene, 5-chloro-1,4-naphthylene, 1,5-naphthylene and 2,6-naphthylene. Examples of diamines and diamine carbamates which are suitable as crosslinking agents are: Ν, Ν'-dicinnamylidene-l, 6-hexanediamine, trimethylenediamine, cinnamylidene-trimethylenediamine, cinnamylidene-ethylenediamine, cinnamylidene-hexamethylenediamine, hexamethylenediamylidene-methylene carbamate, 4-hexamethylenediamine carbamate, 1,3-diaminopropane monocarbamate, ethylene diamine carbamate and trimethylene diamine carbamate. The crosslinking agent is used in an amount of about 0.1 to 5 parts by weight per

609886/1109 original inspected

100 parts of fluoropolymer used.

As an accelerator can use the following types of compounds that are already considered suitable for acceleration of the crosslinking of fluoropolymers are known, can be used alone or in combination:

1) Quaternary ammonium compounds, e.g. compounds of the formula

[R ₃ ¹ NR ² -NR ₃ ³ ] ⁺² [X " ^m ] 2 / m

wherein X is an anion (for example, sulfate, acetate, phosphate, _halo: halide, hydroxide, alkoxide and phenoxide), m is the valence |

2 ability of the anion X (e.g. 1 to 3), R is an alkylene radical with 2 to 12 (preferably 2 to 6) carbon atoms or a phenylenedialkylene radical with 8 to 12 carbon atoms (e.g.

-CHp-CgH ₄ -CHp-), R is an alkyl radical with 1 to 12 (preferably 1 to 6) carbon atoms or an aralkyl radical with 7 to
12 carbon atoms, and R ¹ , R ³ and R ^{5 are} alkyl radicals with 1 to; 18 (preferably 1 to 12, in particular 1 to 6) carbon atoms are, as in US Pat. No. 3,655,727 and in IT-PS
932 319.

2) Quaternary phosphonium compounds and related ones
Compounds of the formula;

R ₁ -PR,

¹ I ³

where P stands for phosphorus, arsenic and antimony, R> ,, R ₂ , R ₃ and R ₄ individually for C ^ -CpQ-alkyl radicals, -aryl radicals, -aralkyl radicals, -alkenyl radicals and those with chlorine, fluorine, bromine, cyano, -OR and -COOR substituted analogues of these

609886/1109

Radicals, R stands for a C ^ -Cpo-alkyl radical, -aryl radical, j -aralkyl radical or -alkenyl radical, X for a halide,
Sulphate, sulphite, carbonate, pentachlorothiophenolate, tetrafluoroborate, hexafluorosilicate, hexafluorophosphate, dimethyl phosphate or C ^ -C ^ Q-alkyl-, -aryl-j -aralkyl- j or -alkenyl-Z-carboxylate- or -dicarboxylate and η stands for '1 or 2 and corresponds to the valence of the X anion. Special connections of this type are used in
U.S. Patents 3,876,654 and 3,712,877.

3) Pentasubstituted guanidines of the formula R-i NR.- R,

\ H ^{5 3}

N-C-N

wherein R ^, Rp, R-, R. and R ₁ - independently represent alkyl, cycloalkyl, aralkyl or aryl having 1 to 20 carbon atoms
can, but not more than two radicals are aryl radicals
and any two radicals together form a ring structure
can form, and salts of these guanidines with a
organic or inorganic acid and trisubstituted amidines of the formula j

NR ₉ R ₇

^R 8

wherein Rg, R ", Rg and _Rg are independently alkyl, cycloalkyl, alkyl or aralkyl having 1 to 20 carbon atoms, and any two of these substituents may form a ring structure together ■. These guanidines and amidines
are described in U.S. Patent 3,686,143.

4) Cyclic polyethers, which are made up of about 4 to 10 units
of the formula -0-X- and -0-Y-, where X and Y are divalent radicals which are independently selected from the following
Group selected are:;

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(away)

-CH ₂ -CH-

(C)

wherein R is hydrogen or methyl and at least one of these radicals X and Y is a radical of the formula (a). These Polyethers are described in U.S. Patent 3,580,889.

5) Open chain polyethers of the formula

R-0-4- (CH-) -CH-O 2 m

where "R is hydrogen or C.-C.-alkyl, m is 1 to 3, R ^{1 is} hydrogen or methyl and η is an integer sufficient to give the polyether a molecular weight of at least about 150 These polyethers are described in US Pat. No. 3,524,836. The amount of accelerator used is generally from about 0.1 to 3 parts by weight per 100 parts of polymer. Accelerators of types (1) and (2) are preferred. wherein benzyltriphenylphosphonium chloride is particularly sawn _t vorzugt.

Die'erste vulcanization of the vulcanizable mixture is preferably carried out by heating about 1 to 60 'minutes in the press to about 149-204 ⁰ C \ is. Usual rubber vulcanization presses, molds and the like. Which with suitable heating and vulcanization! means provided can be used. If a product with maximum heat resistance and dimensional accuracy is required, post-vulcanization is preferred.

609886/1109

ORIGINAL INSPECTED

sation made in which the molded part is another
Time from about 1 to 48 hours to about 180 to 300 ° C

is heated. The best vulcanization time and temperature

i rature for a particular application depend on factors ι

such as the type and proportion of the ingredients and the!

properties desired in the end product. i

The 'fluoropolymers with known fillers, pigments, j pore forming agents and other additives overall' can be mixed for preparing the vulcanizable mixture. ' Any .apparatus suitable for the
Manufacture of rubber mixtures suitable, for example roller mixers, Banbury mixers or extruders, can be used to produce the vulcanizable mixture. ¹

The fluoropolymers according to the invention can be used as coatings used for wires and cables and for similar purposes.

The invention is further illustrated by the following examples. In these examples all relate
Quantities in parts, percentages and proportions by weight, unless otherwise stated; ben.

Examples

Three polymers (A, B and C) are produced as follows: tetrafluoroethylene, vinylidene fluoride and hexa-! fluoropropene are mixed in the proportions given in Table 1. The mixture is compressed
and fed in the stated quantities to a 2-liter stirrer autoclave made of stainless steel. Simultaneously
deoxygenated water which contains the catalyst components, sodium hydroxide, a chain transfer agent (diethyl malonate for polymer A) and
a surfactant (ammonium perfluorooctanoate
for the polymers B and C) in the stated amounts

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introduced into the autoclave. The autoclave is at

a temperature of 100 to 110 ⁰ C under a pressure ■

of 63 atmospheres kept filled with liquid. Under j

The monomers are polymerized under these conditions;

wherein a suspension of polymer particles in water ge-j forms is. The suspension is continuously released from the top of the reactor through a pressure reducing valve. ! withdrawn and degassed to remove residual monomers. The polymer is coagulated, filtered off, labeled with J Washed with water and dried in a hot air oven.

■ I

Table 2 shows the following for the polymers
Properties calledi melt index, determined according to
ASTM D-1238 at 250 ° C using a 0.79 mm! Nozzle and a 7 kg weight on a piston; Firming | performance properties, determined on an Instron tensile testing machine in accordance with ASTM D-412 using: Standard samples for the tensile test, which were cut from polymer ^{sheets which were pressed at temperatures of at least 20 °} C. above the melting range of the polymer, ■ and the glass transition temperature t and the crystal melting temperature t, each determined with the differential scanning calorimeter (DSC), in which the polymer samples are tempered for 2 days or more at room temperature, then cooled to -50 ° C. and at a rate of 10 ° C./minute be heated. The heat of fusion ^ h.
a measure of the degree of crystallinity of the polymer, is calculated from the area of the melting endotherm and DSC calibration parameters

meters determined. !

100 parts of the polymer B are 2.3 parts
Hexafluoroisopropylidene-bis (4-hydroxybenzene), 0.9 parts of i benzyltriphenylphosphonium chloride, 6.8 parts of magnesium oxide and ¹ 4 parts of calcium hydroxide mixed into a vulcanizable \ cash mixture. The components are in
Mixed powder form. The finely divided mixture j obtained is pressed into a film. A 0.254 mm thick film

60 9 8 86/1 109

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the mixture is placed in the press at 200 ° C. for 30 minutes

2 '

and vulcanized 140 kg / cm. The vulcanized film; has approximately the same yield stress and the same j Module like the unvulcanized polymer B, but a ·; lower elongation at break of 190% and a reduced ■ ·. Deformation rest of 70%. This is a sign of; successful vulcanization of the polymer mixture.

The polymers A, B and C are vulcanizable fluorine, polymers having a very advantageous and überraschen- \ the combination of properties. You can use ■ vulcanizing agents, which are usually used for the
Vulcanization of fluoropolymers used the
are elastomeric and not plastic, vulcanized! will. They have a at normal room temperature
Rigidity similar to that of many common thermoplastics. They can be easily processed at high temperatures. For example, this can be
heated material by pressing, injection molding and
Process extrusions into good molded parts. Further
these polymers have good heat and solvent resistance

resistance. ■

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Tabel Polymerization conditions Polymer A Polymer B Polymer C

Temperature; C Pressure, psig (kg / cm ² ) ^{Residence time a} ), minutes Amount of water supplied, liters / hour. Charge with monomers Total, g / hr.

Weight * tetrafluoroethylene (TFE) / Vinylidene fluoride (VF) / hexafluoropropylene (HFP)

(NH ₄ J ₂ .SO *

OH,

S ₂ O ₈

g / h

g / h

NaOH, g / h Diethyl malonate, cm ^ / hr. Ammonium perfluorooctanoate, g / h

Monomer conversion,% Residual gas, wt% TFE / VF / HFP

Polymer dispersion PH% by weight solids Polymerization rate, g / hr

Composition of the polymer% by weight TFE / VF / HFP 110 (63) 15 8.0

1700 49/36/15

8.0 1.2 2.4 8.0 0

93

7/5/88

3.0 16.5 1580

52/39/9

100

900 (63) 30 4.0

1000 50/24/26

1.4b) 0

0.5 0 16.0

84 12/2/86

17.4 840

57/28/15

a) Nominal residence time = reactor volume (2.0 1) -for water flow rate (vol.)

b) Na ₀ S _n O ₀ was used instead of (NH.) _ S_O _Q.

ZZo 4 Z Z

110

900 (63) 15 8.0

1300 63/16/21

8.7 J 0 i 3.0 I 0 24.0

88! 14/0/86

2.6 12.6 1150 ^

CD 70/18/12 cn

T a b e 1 1 e 2; Properties of the polymers.

Composition, wt% TFE / VF / HFP polymer A
52/39/9

Polymer B 57/28/15

Polymer C 70/18/12

co co »

Melt flow rate, g / 10 min. 250 ° C / 7000 g

Thermal analysis, differential scanning calorimeter, freezing temperature (t), ⁰ C

Crystal melting temperature (t), ^{0 C}

Maximum (peak) area

Stress-strain properties measured at 24 ° C_

Yield stress, psi (kg / cm ² )

Modulus at 100% elongation, psi (kg / cm ² )

Tensile Strength at Break, psi (kg / cm ² )

Elongation at break,%

Deformation rest,%

measured at 100 ⁰ C:

Yield stress, psi (kg / cm ² )

Modulus at 100% elongation, psi (kg / cm ² )

Tensile Strength at Break, psi (kg / cm ² )

Elongation at break,%

Deformation rest,% Shore D hardness 1040

-5

140

125-155
1.4

(82)
(73)
(109)

390

315

(31)

(27)
85

48

-2

170

150-180 1.1

1030 (72) 1800 (126) 3810 (267)

360

230

360 (25)

440 (31)

> 1350 (94)> 370

> 260
50

770

10

205

155-240 3.6

1760 (123) 1540 (108) 1590 (111)

270

215

45 (3) 55 (4) 70 (5) 350

56

Claims (8)

Claims essentially from ^:. ·, ■] a) about 50 to 85% by weight of tetrafluoroethylene units, b) about 10 to 45 wt .-% vinylidene fluoride units and c) about 5 to 40% by weight of hexafluoropropylene units. 2. Fluoropolymers according to claim 1, consisting of i a) about 50 to 80% by weight of tetrafluoroethylene units, b) about 15 to 40 wt .-% - vinylidene fluoride units and ι c) about 5 to 20% by weight of hexafluoropropylene units. | 3. Vulcanizable plastic mixtures containing J a fluoropolymer according to claim 1 and one for the | Vulcanization of fluoropolymers suitable Crosslinking agents. ' 4. Mixtures according to claim 3, characterized in that they contain an aromatic polyhydroxy-I compound as a crosslinking agent. _; 5. Mixtures according to claim 3 and 4, characterized in that they are hexafluoroisopropyli- as crosslinking agent; contain den-bis- (4-hydroxybenzene). j 6. Mixtures according to claim 3 to 5, characterized in that net that they have a vulcanization accelerator from the ι contain a group consisting of quaternary phosphonium compounds and quaternary ammonium compounds. 7. Mixtures according to claim 3 to 6, characterized in that! net that they use benzyltriphenylphos- j as an accelerator contain phonium chloride. 8. Mixtures according to claim 3 to 7, characterized in that net that they also ^{contain at least one bivalent:} metal oxide and / or metal hydroxide. i 6098S6 / 1 109