RU2554886C1 - Fluoroplastic pore-forming composition and method of producing fluoroplastic pore-forming composition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: disclosed is a fluoroplastic pore-forming composition, which is a polymer base consisting of a mixture of thermoplastic fluorplastic F-4MB class B or K in the form of granules and VH or V in powder form and a pore-formation regulator, wherein the polymer base is taken in amount of 99.0-99.5 wt % of the fluoroplastic pore-forming composition and the pore-formation regulator in amount of 0.5-1 wt % of the fluoroplastic pore-forming composition. The F-4MB class B or K is taken in amount of 70-80 wt % of the polymer base and F-4MB class VN or V is taken in amount of 30-20 wt % of the polymer base. The pore-formation regulator is either only boron nitride in amount of 0.5-1 wt % of the fluoroplastic pore-forming composition, or composite pore-formation regulator consisting of boron nitride in amount of 0.25-0.5 wt % of the fluoroplastic pore-forming composition or titanium dioxide in amount of 0.01-0.25 wt % of the fluoroplastic pore-forming composition. A method of producing said composition is also disclosed.

EFFECT: uniform distribution of the pore-formation regulator in the fluoroplastic pore-forming composition for further use when applying an insulation layer from the fluoroplastic pore-forming composition on a cable conductor by extrusion while simultaneously using a physical foaming process by feeding a gaseous blowing agent into the extruder; the composition is obtained from readily available components produced locally.

2 cl, 5 tbl, 5 ex

Description

Technical field

The invention relates to a fluoroplastic pore-forming composition (FPK) for creating reliable lightweight insulation of radio frequency cables with improved weight and size characteristics, good dielectric properties and a long service life in the temperature range from -60 to + 200 ° C at a high signal transmission rate and low attenuation. To use conductive materials as a porous insulation of wires and cables, a composition is required that ensures the formation of a uniform pore structure, which is achieved by the uniform distribution of the pore formation regulator (RP) in the polymer base (PMO).

State of the art

As the PMO for FPK in the present invention, a commercially available copolymer of tetrafluoroethylene with hexafluoropropylene (TFE / HFP) is used. A method for producing a TFE / HFP copolymer is known, for example, from the Russian patent RU 2206580 Cl "METHOD FOR PRODUCING TETRAFLUORETHYLENE HEXAFLUOROPROPYLENE COPOLYMERS" (IPC C08F 214/26, publ. 06/20/2003), including copolymerization of monomers in monomers or monomers containing monomers or monomers containing monomers solvent at a temperature of 25-50 ° C and a pressure of 1.1-1.5 MPa in the presence of a perfluorinated radical initiator, using a loading mixture of monomers containing 80-86 mol%. hexafluoropropylene and 14-20 mol%. tetrafluoroethylene, and by feeding the reaction medium during the copolymerization of a mixture of monomers containing 12-15 mol%. hexafluoropropylene and 85-88 mol%. tetrafluoroethylene, followed by removal of unreacted monomers and heating the resulting copolymer to remove initiator residues, characterized in that after the copolymerization process is completed, the reaction mass is cooled to a pressure drop of 0.3-1.0 MPa, after which it is squeezed into a closed volume under a pressure of 0.05-0.1 MPa lower than the pressure in the reaction zone, and unreacted monomers and, if necessary, a solvent are removed in the indicated closed volume while stirring with a stepwise rise ohms of temperature, first up to 50-60 ° С until the pressure is established 0.2-0.3 MPa, and then up to 120-200 ° С until the pressure is set 0.09-0.11 MPa, with periodic pressure relief to the initial pressure when it is increased by 0.1-0.12 MPa and with subsequent heating of the obtained copolymer powder at a temperature of 120-200 ° C and a residual pressure of 0.0026-0.0052 MPa for 3-4 hours

The quality of TFE-HFP copolymers according to the indicated method has been significantly improved, since a homogeneous, non-clumping copolymer powder does not require subsequent grinding, which is also important for the application of PMO as insulation on an electric wire core. The method allows to obtain a TFE copolymer with HFP of a wide range of brands (with PTR from 2 to 15 g / 10 min), with good thermal stability, high physical and mechanical properties while maintaining high removal of the finished product from a unit volume of the reactor, which with a shorter post-polymerization treatment and reduction of the amount of waste provides high economic performance of the process. The resulting copolymers are capable of being processed by extrusion, including cable insulation, and can be widely used in electrical engineering, in the radio and electronic industries, and in other sectors of the national economy.

Separate solutions are known from the prior art relating to the use of boron nitride (BN) as an RP in the composition of FPK in an amount of 0.1 wt%. up to 2% of the mass. from the total mass of FPK, and to obtain FPK by mixing at least two copolymers: tetrafluoroethylene with hexafluoropropylene (TFE / HFP). BN is an excellent thermal and electrical insulator (band gap of 3.7 eV at room temperature). Known as an RP since 1963 (see US Pat. 1963.) In general, foaming of FPK occurs when the cable core is extruded by extrusion of a thermoplastic composition with the supply of a physical foaming agent (nitrogen, carbon dioxide, etc.). US Pat. No. 3,072,583 also states that when foaming a fluoropolymer thermoplastic material, its dielectric constant decreases due to the formation of many small unconnected oh cells of emptiness.

From another US patent US 4764538 "A FOAM NUCLEATION SYSTEM FOR FLUOROPOLYMERS" (IPC C08J 9/00, C08J 9/04, C08J 9/12, C08K 3/00, C08K 3/24, C08L 27/12, publ. 16.08. 1988) it is known the use of RP, which includes boron nitride BN in an amount of 0.02 ... 2% of the mass. of the total weight of the RP, preferably from 0.05 to 1.0%, and one or more applicable inorganic salts in the amount of ppm concentration of 25 ... 1000 ppm (ppm), preferably from 100 to 500 ppm. Inorganic salts such as sodium tetraborate, potassium tetraborate, calcium tetraborate, sodium carbonate, lithium carbonate and potassium sulfate are thermally stable at extrusion temperature and significantly increase the nucleating effect when used together with boron nitride. Inorganic salts may be added as a concentrate, may be premixed with boron nitride. The particle size of the inorganic salt should be no more than 20 microns, preferably not more than 5 microns.

Fluoropolymers suitable for the manufacture of the composition may have a melt flow rate of 1 to 100 g / 10 min and are selected from the following groups:

a) homopolymers of chlorotrifluoroethylene (CTFE) or 2,2-difluoroethylene,

b) copolymers of TFE and one of the aforementioned monomers (a),

c) copolymers of at least one of the aforementioned monomers (a) or (b) and one or more monomers selected from the group: ethylene, perfluoroalkyl ethylene, perfluoroalkyl vinyl ethers. Most preferred are tetrafluoroethylene / hexafluoropropylene, tetrafluoroethylene / perfluoropropyl vinyl ether (TFE / PFPVE), ethylene / tetrafluoroethylene / perfluorobutylene, ethylene / chlorotrifluoroethylene, polyvinylidene fluoride.

In the examples (1-4, 9-11) of the aforementioned US patent, TFE / HFP copolymers (SP) with a melt flow rate (MFR) of 6.6 g / 10 min at a temperature of 372 ° C were used, in example 8 SP tetrafluoroethylene with perfluoropropyl vinyl ether with a MFI of 14.7 g / 10 min at 372 ° C, in Example 5, a SP of ethylene with tetrafluoroethylene with MF of 14 g / 10 min at 372 ° C, in Example 6, of a joint venture of ethylene with chlorotrifluoroethylene. Foamed insulation is produced by extrusion with a continuous supply of chlorodifluoromethane, which is highly soluble in fluoropolymers. The void volume in the samples obtained by extrusion was an average of 50%, pore sizes ranged from 115 μm to 500 μm.

The disadvantage of the composition and method according to the specified US patent is the use of chlorodifluoromethane when foaming insulation, which is highly toxic and dangerous to the ozone layer. The patent protects the use of nitrogen, carbon dioxide or other gases, without giving examples, while it is known that nitrogen and carbon dioxide dissolve worse in fluoropolymers.

From the patent of European Patent Organization EP 0684272 B1 “FOAMABLE SOLID COMPOSITIONS BASED ON PERFLUOROPOLYMERS AND PROCESS FOR THE PREPARATION THEREOF”, (IPC B05D 7/24, C08J 9/00, C08J 9/14, C08K 3/00, C08K 3/38, C08L 27/12, C08L 57/00, C08L 87/00, H01B 13/14, H01B 3/30, H01B 3/44, H01B 7/02, H01B 7/29, publ. 11/29/1995) known use in fluoropolymer compositions based on thermoplastic perfluoropolymer (A) with fluoropolyether in an amount of from 0.05 to 20% of the mass. by weight of A and boron nitride BN in an amount of 0.02-2 wt%, by weight of polymer A as a pore formation regulator (RP). As polymer A, a thermoplastic perfluoropolymer selected from the group of, for example, TFE / HFP copolymer, tetrafluoroethylene / perfluoromethylvinyl ether (TFE / PFMVE), TFE / PFPVE (see claims 1-4 of the patent claims) can be used. In the examples, the volume of voids in insulation with various fluoropolymers, which is from 30 to 60%, is given. In comparative examples (13-16), without the use of fluoropolyethers, the void volume is 0%, and in examples 13 and 14, boron nitride BN (particle size 5 μm) in an amount of 500 ppm is used as RP. In the examples, the best values for the volume of void in isolation are shown in the composition with TFE / HFP, using 6% of the mass. perfluoropolyether GALDEN (R) Ausimont grade D-40 and 0.05% of the mass. boron nitride.

This patent does not provide data on pore size and their distribution.

Technical solutions known from these two patents disclose the object of study only in terms of the use of boron nitride as a RP in an amount of up to 2% of the mass. from FPK, in terms of use as part of a complex RP (PSA) and in terms of using SP TFE / HFP as a PMO composition.

U.S. Patent US 6506809 B2 «TITANIUM DIOXIDE NUCLEATING AGENT SYSTEMS FOR FOAMABLE POLYMER COMPOSITIONS» ( IPC C08J 9/00, C08K 3/00, publ. 14.01.2003) discloses a system for foaming nucleating thermoplastic fluoropolymer based on titanium dioxide TiO _2. TiO ₂ - is known as a white pigment in standard applications (plastics, paints), which protects the polymer base from UV rays and destruction during operation. Heat-resistant, band gap - 3.05 eV at room temperature. Mentioned as a possible RP in the above US patent US 3072583 without giving examples. More affordable than boron nitride BN. The nucleating system, in addition to TiO ₂ , also includes inorganic salts and, optionally, sulfonic and / or phosphonic acid salts.

A foamable composition for insulation comprising a PSA is described. As the PMO used in the patented invention, are given:

1) homopolymers of CTFE, 2,2-difluoroethylene, vinylidene fluoride (VDF).

2) SP trifluoroethylene and monomer selected from the group of CTFE, 2,2-difluoroethylene, VDF.

3) SP of at least one monomer selected from the group of TFE, CTFE, 2-2-difluoroethylene, VDF and combinations thereof and one or more monomers selected from the group consisting of HFP, ethylene, perfluoroalkyl vinyl ether (PFAVE) and monomers, groups of dioxols, for example perfluorodioxole, perfluoro (2,2-dimethyl-1,3-dioxole) and perfluoro (5-methoxy-1,3-dioxole), as well as combinations thereof.

The PMO protected in the patent has an MFI melt flow rate (measured according to ASTM D1238 at a temperature corresponding to the polymer) from 1 g / 10 min to 100 g / 10 min. Preferably from 5 g / 10 min to 35 g / 10 min. Also in the examples of the patent, SP TFE / PFAVE (HYFLON MFA 6012) with an MF of 18.3 g / 10 min was used as a PMO.

The composition containing titanium dioxide TiO ₂ , sodium tetraborate and barium salt in a mixture of perfluoroalkylethanesulfonic acids was considered as a PSA. The ratio of components by weight based on the total weight of the composition for titanium dioxide is from 50 to 2000 ppm for an inorganic salt including lithium carbonate, calcium carbonate, strontium tetraborate, sodium carbonate, sodium tetraborate, sodium sulfite, potassium tetraborate, potassium pyrosulfate, sulfate potassium, barium nitrate, aluminum phosphate, sodium silicofluoride and their combinations by weight from the total weight of the composition from 25 to 3000 ppm and for sulfonic acid and salts of phosphonic acids or their combinations by weight based on the total weight of the composition from 100 to 3000 pp m.

As a PSA, we used a composition with a ratio of components by weight based on the total weight of the composition on titanium dioxide 250 ... 2500 ppm, on sodium tetraborate 100 ppm (as an inorganic salt), on the barium salt of sulfonic acids 250 ppm. As a comparative example, a PSA with boron nitride of the CTF-5 grade from Carborundum (250 ppm and sodium tetraborate - 100 ppm) is given.

The achieved void volume during extrusion of the composition into porous insulation on a special unit with a nitrogen supply is 24.5 ... 33.5%. When using boron nitride as a PSA, the cell size was 80.8 μm; when using a PSA with titanium dioxide, the cell size was 55 ... 78 μm. The dependence of the cell shape on the titanium dioxide content in complex RP is also shown.

Despite the fact that a fluoropolymer base (FPO) is patented with an MFR of 1 g / 10 min to 100 g / 10 min, examples are given on TFE-PFAVE copolymers with a melt flow rate of about 18.3 g / 10 min.

The solution, known from US Pat. No. 6,506,809, discloses an object of study only in terms of features characterizing the possibility of using titanium dioxide in the composition of the PSA distributed in the PMO.

The closest in technical essence are the composition and method of its manufacture from a mixture of at least two SP TFE / HFP or FEP (fluorinated-ethylene-propylene - PEP A) and triple SP tetrafluoroethylene / hexafluoropropylene / perfluoroethyl vinyl ether (TFE / HFP / PFEVE - FEP B), ensuring the adhesion of the composition to the core of the electric wire, see US patent US 7638709 B2 “FLUOROPOLYMER WIRE INSULATION” (IPC НВВ 7/00, published on December 29, 2009), which describes a fluoroplastic composition intended for the formation of porous insulation used in the production of coaxial x cables.

The technical result of this patent is to reduce the reflection loss coefficient in a coaxial cable, including in a foam layer.

The fluoroplastic composition is obtained from a mixture of SP, while one of these SP has an adhesion of at least about 13.3 N, and the other adhesion is not higher than 11.1 N, and said mixture of SP has an adhesion of at least 13, 3 N. The number of FEP A and FEP B can be from 30 to 70% of the mass. of the total weight of the mixture, in a particular example implementation of the invention it is indicated that the composition is obtained from a mixture of two FEP - FEP A and FEP B, taken in a dry ratio of 50 weight parts of each, and RP, and RP is taken in an amount of 0.25% of the total weight of the composition. As RP, a mixture is used including a mixture consisting of 91.1% of the total weight - boron nitride, 2.5% of the mass. - calcium tetraborate and 6.4% of the mass. - barium salt of sulfonic acid. From this mixture prepare 2.5% of the mass. the concentrate that is extruded. The obtained granules of the concentrate are mixed with PEC granules and used for applying porous insulation. To obtain porous insulation, a standard extrusion method is used when applying gas under high pressure to foaming the melt. When implementing the technical solution, a fluoropolymer with an MFR of 7 g / 10 min, containing 10 ... 11% of the mass, was used as a PEC hexafluoropropylene, the rest is tetrafluoroethylene. The polymer was stabilized by wet steam treatment so that its end groups were converted to stable — CF ₂ H groups. As FEP B, a triple fluoropolymer containing 10-11% of the mass was used. from the total weight of hexafluoropropylene, 1-1.5% of the mass. of the total weight of PFEVE, the rest is tetrafluoroethylene.

FEP B has an MFI of 30 g / 10 min and an effective amount of end groups having an affinity for the wire material, the remaining end groups — CF ₃ groups, are obtained by fluorination. The MFI of the composition is 14 g / 10 min.

Thus, in US Pat. No. 7,638,709, an object of study is disclosed only in terms of the features characterizing the FPK and its preparation based on a mixture of SP TFE / HFP and triple SP TFE / HFP / PFEEV with a large difference in the MFI values. Obtaining a triple joint venture is a rather complicated separate technological process, which together complicates and increases the cost of the composition.

Disclosure of invention

The objective of the invention is to create a formulation based on available components produced by the domestic industry for a fluoroplastic pore-forming composition (FPK) and a method for its preparation, which further ensures the manufacture of porous cable insulation with good uniformity of pore structure with a long service life at high temperatures, with good dielectric performance at a high speed signal transmission in the wire and its low attenuation.

The technical result is the provision of high-quality uniform distribution of RP in the FPK, for further use in the process of applying the insulation layer from the FPK to the cable core by extrusion with the simultaneous application of the physical foaming process by supplying a gaseous blowing agent to the extruder.

The technical result achieved is achieved by the composition of the composition described below and the method of its production (given the fact that the composition as an object of the invention is new, the method of its production is also new). FPK is a polymer base of a mixture of thermoplastic fluoroplastics F-4MB grades "B" or "K" in the form of granules and "BH" or "C" in the form of a powder. In this case, the fluoroplastic F-4MB brand "B" or "K" is taken in an amount of 70 ... 80% of the mass. PMO and ftoroplast F-4MB brand "VN" or "B" respectively taken in the amount of 30 ... 20% of the mass. PMO. Moreover, the PMO is taken in the amount of 99.0 ... 99.5% of the mass. FPK, and RP taken in the amount of 0.5 ... 1% of the mass. composition. RP represents or only boron nitride BN in an amount of 0.5 ... 1% of the mass. composition or a complex regulator of boron nitride BN in an amount of 0.25 ... 0.5% of the mass. composition in combination with titanium dioxide TiO ₂ in an amount of 0.01 ... 0.25% of the mass. composition. Boron nitride has an average powder particle size of 14 ... 21 microns, more preferably 5 ... 10 microns, and other possible components of RP, especially titanium dioxide, have a particle size of not more than 20 microns, preferably 5 ... 10 microns.

A method of obtaining the specified fluoroplastic pore-forming composition is characterized in that it contains at least stages in which granules or> * powders of thermoplastic fluoroplastics F-4MB of different grades are dried; dry and sift components RP; if necessary, particles of boron nitride BN are dispersed to an average particle size of 14 μm (more preferably up to 5 μm). A concentrate of a regulator or a complex pore formation regulator is prepared, F-4MB of brands B and C are mixed with each other and then with RP concentrate from boron nitride to produce FPK, or F-4MB of brands VN or B is mixed with the prepared mixture PSA to obtain a PSA concentrate and then this concentrate is mixed with granules F-4MB grades "B" or "K" to obtain a fluoroplastic pore-forming composition. Next, the obtained fluoroplastic pore-forming composition is extruded to obtain strands with their subsequent granulation. If necessary, repeated extrusion is possible followed by granulation of the fluoroplastic pore-forming composition.

The implementation of the invention

The analysis of patent documents showed that at the search completion date no solutions were found whose combination of essential features coincides with the combination of essential features of the object of study. In the course of the patent information search, no sources were revealed that indicated the impossibility of using the technical solution described by the object of study in industry. In addition, experimental data confirming the possibility of industrial application of a technical solution are presented as initial data.

Grades “B” and “K” of thermoplastic fluoroplastic-4MB are in granules, grades “B” and “VN” are powders. The main difference between brands - in the size of PTR and other characteristics. Grades “B”, “C” and “BH” are produced according to TU 301-05-73-90, grade “K” - according to TU 6-05-041-909-88 with changes 1, 2, 3. Instead of powder brand "VN" you can use the powder of the brand "V" when the dielectric properties of the brand "B". Instead of granules of brand "B", granules of brand "K" can be used to obtain a composition with a large MFI, to improve the processability of the composition into porous insulation.

The preparation of the composition is carried out either by stepwise mixing or by single-stage mixing of the components, in other words, the process of mixing the starting components is carried out in several ways: the starting powder components are mixed manually by shaking in a polyethylene container, followed by mixing the mixture of the obtained powder mixture with granules in a high-speed mixer; or mixing the powdered components is immediately carried out in a mixer.

The PSA mixing process is also carried out in several ways: direct mixing of the components in a polyethylene container; or mixing the components together multiple screening through a sieve 005 or 0063; or mixing components in a mixer equipped with a frame or paddle mixer.

The following examples illustrate the invention.

Tables 1 ... 5 contain summary data from embodiments of the invention.

As TFE, SP TFE / HFP were used, which are a mixture of thermoplastic fluoroplastic F-4MB grades B and V in a ratio of 80/20.

The name and designation of the components of the RP used in the examples are presented in table 1, the composition of the RP is shown in table 2.

Potassium tetraborate (K ₂ B ₄ O ₇ ), which showed good results in pore size in US Pat. No. 4,764,538 when used as part of PSA, is used in comparative example 1 as part of PSA FPK, the results are shown in Table 5.

It is important to note that in the present invention, when TiO _{2 is} combined with BN, an improvement in the dielectric properties of FPK was first detected, in terms of the “Dielectric loss tangent at a frequency of 10 ⁶ Hz," data are presented in table 2.

Modes of obtaining FPK on a single screw extruder with a ratio of screw length and diameter equal to 25 are shown in table 3.

In the course of its processing, FPK into porous insulation on a special extrusion unit with nitrogen supply, samples were obtained in the form of a porous bundle by passing the molten mass through the bypass of the unit, and when passing through the extrusion head of the unit - in the form of porous wire insulation. The conditions for obtaining porous samples are presented in table 4.

, The cell size was determined from a photograph of a thin cross-section of the sample at approximately 25-fold magnification. The average cell size was calculated by averaging 15 large cells. The void content in the porous sample X, vol.%, Was determined by the formula: $$X=\left(\mathrm{one}-\frac{m}{2.17\cdot \pi \cdot l\cdot \left(R^2-r^2\right)}\right)\cdot \mathrm{one\; hundred}$$

,

where R is the outer radius of the sample, cm; r is the radius of the core, cm; l is the length of the sample, cm; m is the mass of the sample, g

The arithmetic average of three parallel definitions was taken as the result.

The properties of the samples of the bundle ⌀ 2.2 ... 8 mm obtained on the existing equipment (average pore size, void volume, sample density), characterizing the quality of porosity, are presented in table 5.

Example 1. The composition is obtained by stepwise mixing. In the first stage, the components of the RP were mixed in the mixer. At the second stage, F-4MB grade B powder was added to the resulting mixture, at the third stage, F-4MB grade B granules were added to the resulting mixture, after which the composition was extruded according to the conditions indicated in Table 3. Composition of PMO: F-4MB Grades B and F-4MB Grades B in a ratio of 80/20, respectively. The composition of the RP is shown in example 1 of table 2, the extrusion of the FPK is carried out according to the regime of table 3, the extrusion of the FPK by the method of physical foaming to obtain a porous sample is carried out according to regime 1 of table 4, the properties of the porous samples are presented in example 1 of table 5.

Example 2. The composition is obtained by stepwise mixing, as described in example 1. The composition of the RP is shown in example 2 of table 2, the extrusion of the components of the FPK is carried out according to the mode of table 3, the extrusion of the FPK by the method of physical foaming to obtain a porous sample is carried out according to the mode 1 of table 4, properties of the porous image are presented in Example 2 of Table 5. Insulation was obtained with a 50% void volume, providing high dielectric properties with stable values of the "Dielectric loss tangent".

Comparative example 1. The composition is obtained by stepwise mixing, as described in example 1. The composition of the RP is shown in Comparative example 1 of table 2, the extrusion of the components of the FPK is carried out according to the mode of table 3, the extrusion of the FPK by the method of physical foaming to obtain a porous sample is carried out according to the mode 1 of table 4 , the properties of the porous image are presented in Comparative example 1 of table 5.

You can see that when using PSA (BN + TiO ₂ + K ₂ B ₄ O ₇ ) there is a slight increase in pore size (compared with example 2), and the void volume in the sample is comparable to the void volume in the sample obtained from the PMO composition ( Comparative example 3).

Comparative example 2. The composition is obtained by stepwise mixing with the preparation of the concentrate FPK, followed by mixing in the ratio of 1/9 with PMO. The composition of the RP is shown in Comparative Example 2 of Table 2, the extrusion of the FPK components is carried out according to the regime of Table 3, the extrusion of the FPK by the method of physical foaming to produce a porous sample is carried out according to regime 1 of Table 4, the properties of the porous image are presented in Comparative Example 2 of Table 5.

Comparative example 3. The composition of the PMO: F-4MB brand "B" and F-4MB brand "B" in the ratio of 80/20, respectively, without the introduction of RP obtained by mixing the components with subsequent extrusion according to the mode of table 3, extrusion of the PMO by the method of physical foaming to obtain the porous sample is conducted according to mode 2 of table 4. The properties of porous images are presented in comparative example 3 of table 5.

Thus, it has been experimentally proved that the proposed originally obtained fluoroplastic pore-forming composition can be used for its further application as a porous insulation with a thickness of 1.1 to 4 mm on a conductive core of cables designed to transmit electronic signals of different frequencies.

Claims (2)

1. Fluoroplastic pore-forming composition (FPK), which is a polymer base (PMO) from a mixture of thermoplastic fluoroplastics F-4MB grades "B" or "K" in the form of granules and "BH" or "B" in the form of a powder, and the fluoroplastic F- 4MB of grade “B” or “K” was taken in an amount of 70-80 wt.% PMO and fluoroplastic F-4MB of grade “VN” or “V” respectively was taken in an amount of 30-20 wt.% PMO, with PMO taken in an amount of 99 , 0-99.5 wt.% FPK, as well as a pore formation regulator in an amount of 0.5-1 wt.% Of the composition, the regulator being either only boron nitride ΒΝ in an amount of 0.5-1 wt.% composition, or a complex regulator of boron nitride ΒΝ in an amount of 0.25-0.5 wt.% of the composition in combination with titanium dioxide TiO ₂ in an amount of 0.01-0.25 wt.% of the composition, and boron nitride has the average particle size of the powder is 14-21 microns, preferably 5-10 microns, and other possible components of the pore formation regulator, primarily titanium dioxide, have a particle size of not more than 20 microns, preferably 5-10 microns. 2. A method for producing a fluoroplastic pore-forming composition according to claim 1, characterized in that it contains at least stages in which granules or powders of thermoplastic fluoroplastic F-4MB of different grades are dried; dry and sift the components of the pore formation regulator; if necessary, disperse boron nitride particles ΒΝ to an average particle size of 14 microns, more preferably up to 5 microns; prepare a concentrate of a regulator or a complex pore formation regulator, mix F-4MB of brands B and C with each other and then with a concentrate of a pore formation regulator from boron nitride to obtain a fluoroplastic pore-forming composition or mix F-4MB of brands VN or B with a prepared mixture of a complex pore-forming regulator to obtain a concentrate of a complex pore-forming regulator, and then this concentrate is mixed with F-4MB granules of grades “B” or “K” to obtain a fluoroplastic pore-forming composition, then ext Udyr resulting fluoroplastic pore-forming composition to obtain strands with subsequent granulation.