RU2404997C2 - Method for industrial production of modified polymers and device for realising said method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention describes a method for industrial production of modified polymers in accordance with which a ground polymer undergoes gas-chemical modification in fluidised state using reactive gases, including inert gases and ozone as a gaseous oxidising agent and the obtained activated powder is mixed with a monomer or a group of monomers or a polymer, followed by their copolymerisation through surface-initiated polymerisation in molten stage in an extruder. The method is characterised by that gas-chemical modification is carried out at temperature not higher than 30°C and ozone concentration of 5-15 wt %, while blowing with reactive gases for 10-30 minutes, and polymerisation in the extruder is carried out at 130-230°C, while augers are rotating at 300-500 rpm, L/D of not less than 40, for synthesis of graft and block copolymers with degree of grafting of not less than 80%. The invention also describes a device for realising said method.

EFFECT: cost-effective and environmentally clean industrial method of modifying the surface of polymers with reactive gases with subsequent synthesis of graft and block copolymers through surface-initiated polymerisation.

5 cl, 4 dwg, 5 tbl, 7 ex

Description

The invention relates to the field of polymer chemistry, biotechnology, medicine, and for the implementation of environmentally friendly and cost-effective production of modified polymers on an industrial scale.

In particular, the invention can be used for innovative industrial modification of the surface of polymers and subsequent synthesis of grafted graft and block copolymers, for use as compatibilizers, impact modifiers, elasticizers, thermoplastic adhesives, production of silanol-grafted polyethylene (PEX-b), polymers with increased barrier and fire-resistant characteristics, as well as with the aim of creating composite materials with a unique set of chemical and physical properties for the subsequent their general application in various branches of science and technology.

As a rule, polymeric materials are characterized by low values of surface energy, poorly wetted by solvents, poorly stick together, and have low adhesion to various surfaces.

In addition to the long-known and widespread chemical method of surface modification of polymers, many other methods are being studied, such as: corona discharge; ultraviolet radiation, gamma radiation, electron beam, reactive gases, low-temperature plasma.

One of the most promising and modern methods of surface modification of polymers is the modification of polymers with reactive gases, which allows you to change the properties of the surfaces of these materials in a wide range and significantly expand the scope of their use.

Ecologically clean modern gas-chemical methods significantly benefit in comparison with the chemical modification, which uses such aggressive reagents as acids, hydroxides, alkaline earth metals and their compounds, etc.

By the term "reactive gases" we mean a combination of chemically active and inert gases, one way or another taking part in chemical reactions in the process of modification.

As a rule, well-known oxidizing gases are used as chemically active: chlorine, fluorine, ozone, and inert gases can represent a whole range of gases already present in the atmospheric air (nitrogen, hydrogen, carbon oxides, etc.), and specially introduced into the reactive gas medium (ammonia, helium, argon, etc.).

Comparing processes based on different oxidizing gases, the following can be noted.

Known methods for modifying the surface of polymers with a chlorine-air or chlorine-nitrogen gas mixture (US Pat. No. 5,693,714), where chlorination with a chlorine content of -5% is used, in particular, to activate the surface of secondary rubber (powder) with a view to its further use as a filler in polyurethane or polysulfide compositions.

The disadvantages of this process are its obvious non-environmental friendliness, a sufficiently large chlorine consumption (up to 40%), the need for a cooling jacket to remove heat from the reactor and maintain a temperature of 21 ° C, the possibility of gas leaks from the reactor in case of leakage, as the process occurs at atmospheric pressure .

Known methods for treating polymers with fluorine-containing gases to functionalize the surface of materials, in particular for:

(a) improving the permeability of various synthetic fibers and non-woven materials (US Patent No. 3,940,520; 3,988,491; 4,020,223);

(b) treating the polyester cord for later use in tires (US Patent No. 4,009,304);

(c) reducing the coefficient of friction of various natural and synthetic elastomers (US Patent No. 3,389,098);

(d) enhancing the barrier properties of containers for organic liquids (UK Patent No. 1,244,971; US Patents No. 2,811,469; 3,413,226; 3,992,221; 3,862,284).

In addition, Schonhom, H. et al. (Journal of Applied Polymer Science, vol. 12, pp 1231-7; 1968) describes the fluorination of a polyethylene surface to improve adhesion properties.

However, it is obvious that fluorine is quite toxic and requires expensive gas generators and purification filters when withdrawing from the process.

Direct fluorination has a chain mechanism and can easily go into combustion and explosion. The reaction is highly exothermic and requires large expenditures for efficient heat removal from the reactor. The cost of fluorine gas is more than $ 100 per kg. In addition, some associated products after fluorination may adversely affect the operation of blowing agents, thereby limiting the scope of such a modification.

The advantages of ozone as an oxidizing gas are that it can be generated from air (at a significantly lower cost of ozonizers compared to fluorine generators), and the decomposition of ozone at the exit from the process does not require special filters, it is economically cheap and environmentally friendly (O ₃ decomposes O ₂ in a catalytic destructor).

Compared to the plasma-chemical modification, the modification with reactive gases has a much greater penetration depth, and the free-radical reaction mechanism fixes the modification, making it permanent.

The plasma-chemical process is more superficial, since in the process of modification there is a “breakdown” of surface molecular bonds and further there are commercial problems with the loss of the level of surface functionality over time.

Therefore, the use of ozone as an oxidizing gas, from the point of view of environmental cleanliness and economic efficiency of the process, seems most appropriate.

Methods of surface activation of polymers with ozone or an ozone-air mixture are also mentioned in various patents related to surface modification of polymers and grafting, for example:

(a) the graft polymerization of various monomers on pre-ozonated polysiloxanes carried out in solution is disclosed in US Patent Nos. 3,008,920 and 3,070,573.

(b) the peroxidized polymer obtained after pretreatment with gamma radiation or ozone is copolymerized with the corresponding monomer in solution at elevated temperature and with the introduction of metal ions to inhibit the homopolymerization of the monomer (US Patent Nos. 4,311,573 and 4,589,964 or EP 0378511).

The disadvantage of the described methods is the implementation of grafting in solution (“wet” gas scheme) for a long time (up to several hours), the need to inhibit the homopolymerization of monomers by introducing metal ions into the solution, and the process of drying materials and evaporating reagents takes a long time.

In a similar way (according to the "wet" gas scheme), carbon latex-filled SCS latexes are coagulated (RF Patent No. 2293741 C1), where the obtained wet crumb of the filled rubber is pre-dehydrated on a vibrating screen, subjected to mechanical extraction to a moisture content of 7-10 wt.%, Followed by drying at temperature 105 ° C.

From RF Patent No. 2265029 C2, a method is known for producing hydrophilic porous polyolefin membranes with preliminary activation of a polyethylene surface by ozonation. A distinctive feature of the method is the use as an initiator of a redox system based on hydroperoxide (peroxide) and gaseous sulfur dioxide.

However, the ozonation time in this method was 120 minutes, and the time for bubbling sulfur dioxide gas through the reaction mixture (water, methanol, acrylic acid) was at least 2 hours at a temperature of 0 ° C and at room temperature reached 15 hours.

From the RF Patent No. 2060882 C1, a method and device for processing reinforced rubber-containing products: worn tires, conveyor belts, etc. are known. ozone-containing gas with an ozone concentration of 0.1-10 wt.%. Reinforced rubber waste simultaneously with ozonation is subjected to compressive and tensile loads with a force of 10 to 200 kg until deformations in various parts of the product reach 1 to 50%. And although some principles of the "dry" gas circuit: pre-dried air, sluice, decomposition of the exhaust gas exhaust are similar to the claimed device, however, the known method and device are not applicable for the purposes of the claimed invention.

Close to the claimed invention are the methods and devices described in the works of French researchers: B. Boutevin, Y. Pietrasanta and J. J. Robin, Eur. Polym. J., 27.815 (1991); B. Boutevin, Y. Pietrasanta, M. Taha and T. Sarraf, Eur. Polym. J., 20, 875 (1984); B. Boutevin, J. J. Robin and A. Serdani, Eur. Polym. J., 28, 1507 (1992). C. Brondino, doctoral thesis. University of Montpellier II (1996). US patent No. 663356401 B1, Application for US Patent 2004/0116610 A1.

The meaning of these works is to study methods for preliminary modification of the polymer surface by ozonation followed by graft radical polymerization in a melt or solution in the “live chains” mode using stable free radicals to produce graft and block copolymers with a controlled degree and structure of grafting.

The described reactor for gas modification is intended for “dry” gas-chemical modification with an ozone-air mixture of preliminarily ground polymer powder of 200-600 microns in a “fluidized bed”. However, this known method and devices also have a number of significant disadvantages, namely:

- due to the lack of a cooling system in some devices due to the exothermicity of ozonation, the temperature inside the reactor increased by 2 ° C per minute, and when the temperature reached a critical temperature of 55-60 ° C, the temperature increased already by 10 ° C per minute, which led to coalescence and powder melting in the reactor;

- the reactor type equipped with an oil cooling system had a controlled temperature of no higher than 40 ± 2 ° C and a two-layer “jacket”, which significantly increases the cost of the process;

- the working volume of the reactor was 40 l, and the gas modification time was more than 40-60 minutes with a productivity of 17 g of ozone per hour, which only speaks of the "laboratory" level of the known process;

- ozonation occurs at atmospheric pressure in the chamber (without discharge), which will certainly lead to ozone leaks and violate the environmental friendliness of the process;

- grafting polymerization in solution repeats the drawbacks of the above methods, and the extrusion grafting parameters mentioned in the works (extruder with L / D = 36 with screw speed of 100 rpm) do not allow to receive industrial batches of modified material.

Closest to the claimed method is a method for producing graft polyolefins by carrying out a polymer peroxidation process with a mixture of 2 oxidizing gases: ozone and oxygen and subsequent copolymerization of the monomer with the peroxidized polymer. This method is reflected in US Patent No. 4,443,584 of 04/17/1984.

However, the use of the mixture of oxygen and ozone indicated in the claims of US Pat. No. 4,443,584 is extremely dangerous and can lead to a fire or even explosion inside the reactor, which is an obvious disadvantage.

US Pat. No. 4,443,584 teaches the grafting of a vinyl monomer having at least one epoxy functionality, which greatly narrows the scope of the invention.

The present invention does not limit the list of applicable monomers or groups of monomers.

In US patent No. 4443584, a grafting rate of about 60% is achieved at an ozone concentration of 1.2 wt.% (Or 12 mg / l), which is not comparable with the result when using the inventive method, namely at least 80% at an ozone concentration of 2- 15 wt.% (20-150 mg / l).

When creating this invention, the task was to develop a cost-effective and environmentally friendly industrial method and device for modifying the surface of polymers with reactive gases, followed by the synthesis of grafted graft and block copolymers by surface-initiated melt polymerization.

The claimed invention allows not only to overcome all the aforementioned disadvantages inherent in known methods and devices, but also to demonstrate for the first time an already commercialized industrial process.

The technical result is achieved due to the innovative industrial technological scheme and process parameters of gas-chemical modification and synthesis of grafted copolymers. At the same time, it was possible to increase the safety and environmental friendliness of the process, significantly expand the range of monomers and polymers used for the production of graft and block copolymers, increase the degree of grafting of monomer and compatibilization of the components of block copolymers

The essence of the invention consists in the preliminary grinding of a granular polymer, for example, in a rotary vortex mill with a rotor speed of at least 3000 rpm to obtain finely dispersed polymer powder from 100 to 1000 microns depending on the material while removing all possible metallic and nonmetallic inclusions; functionalization of polymer powder based on controlled modification of the polymer surface with reactive gases in a special modifier reactor, where ozone is used as an oxidizing gas at a concentration of 5 to 15 wt.%, at a temperature not exceeding 30 ° C, and as an inert gas, a whole spectrum of gases already in the air or specially introduced into the reactor, where reactive gases are blown for 10-30 minutes due to pressure and discharge through a polymer powder in the "fluidized" state in the reactor, p bot in the "dry" gas circuit, and wherein the ozone is decomposed to oxygen in the catalytic destructor prior to exhaust to the atmosphere; in mixing an activated polymer powder having hydroxyl, carboxyl, carbonyl and peroxide functional groups with a monomer (or a group of monomers) or a polymer, which are added from 0.1 to 95% by weight for copolymerization with the starting polymer by melt surface initiated polymerization in twin screw extruder with an L / D of at least 40, at a screw rotation speed of 300 to 500 rpm, at a temperature of 130 to 230 ° C for the synthesis of grafted graft and block copolymers with a degree of grafting of at least 80%

The essence of the method of industrial production of modified polymers and a device for its implementation are illustrated by drawings.

Figure 1 presents a schematic flow diagram of a gas modification; figure 2 shows a schematic flow diagram of the synthesis of grafted copolymers.

The primary granular polymer 1 that can be used according to the invention includes ethylene homologues obtained as at low pressure, i.e. linear or high density polyethylene, and at high pressure, i.e. branched or low density polyethylene, amorphous atactic polypropylene, crystalline isotactic polypropylene, copolymers of ethylene with propylene, copolymers of ethylene with vinyl acetate, extra-molecular polyethylene, polyvinylidene fluoride, styrene thermoplastic elastomers, ethylene propylene rubbers.

Standard pellets (3-5 mm) of the polymer are fed by a vacuum loader or screw into the feed hopper of the grinding complex 2, for example, a rotary vortex mill, which is a mechanochemical reactor for the synthesis of fine polymer powder. The separation of possible metallic inclusions is carried out by a special magnetic separator. Inside the grinding chamber there is a multi-section high-speed rotor, which, rotating at a speed of at least 3000 rpm, is able to create local vortex flows in the chamber at speeds of 250 m / s.

The required grinding fineness can be easily set from the control panel depending on the type of material and the required productivity and can range from 100 to 1000 microns (in one pass).

The polymer powder 3 crushed in a mechanochemical reactor (vortex mill) enters the loading hopper of the modifier reactor 4. The gas-chemical modification section consists of two zones:

(a) Ozone-air preparation 5

b) Modifier reactor 4.

The oxidizing gas synthesis occurs from atmospheric air, and the exhaust gas stream is decomposed by a catalytic destructor to oxygen and emitted into the atmosphere

For ozone-air preparation complex 5 is used with an ozone generator, an air dryer with a filter system and a receiver, a scroll oil-free compressor.

The main features of the equipment:

- Computer (sensory) settings of all process parameters (ozone concentration, gas pressure, degree of air drying - dew points, etc.). The ozone generator provides almost 100% oxygen synthesis from air to ozone, the compressor provides a high degree of air purity (without impurities and oils with an integrated air cooler) and drying provides a dew point of -70 ° C.

- Long-life electrodes (from high-tech ceramics) (quartz glass is mainly used in analogues).

- Quiet operation.

- Complete safety of the gas circuit and maintenance of the apparatus

- Compact and lightweight equipment.

For transporting the ozone-air mixture, flexible metal hoses with a stainless steel braid 16 are used.

To ensure quick loading and unloading of material and tightness of locking, reliable slide gates are provided. The mixer-reactor 4 is made of stainless steel. Completely sealed. It has two quick-release covers at the top for periodic cleaning of the camera, if necessary.

The mixing elements can be in the form of countercurrent tapes, plows or blades, providing a constant concentration of material in the unloading area and creating a "fluidized bed" when mixing the powder. The ozone-air mixture is blown through the powder (bottom to top). The introduction of any special gases into the reactor (if necessary) is also provided. In the zone of the mixing chamber there is no excess pressure, on the contrary, a certain pressure is created due to the larger diameter (exhaust) and fan (exhaust). In front of the exhaust fan, a destructor 6 is mounted with a catalytic powder for decomposition of ozone.

Despite the exothermic nature of the ozonation process, the temperature inside the reactor does not rise above + 30 ° C, which is guaranteed by a correctly mounted “dry” gas circuit. The maximum concentration limit for ozone in the working sector where the equipment is located is controlled by a gas analyzer sensor.

Modification of polymers with reactive gases can be represented as a controlled process of oxidation of the surface of the polymer.

This reaction proceeds according to a free radical mechanism. Unstable compounds "ozonides", interacting with the molecular lattice of the polymer, form free radicals and hydroperoxides. Free radicals, in turn, interacting with inert gases in the gas mixture, form functional polar groups on the surface of the polymer: hydroxyl (HO-), carboxyl (HOOO-), carbonyl (-C = O-), peroxide (HO-), amine (NH ₂ -) etc. (the set and chemical nature of the groups is determined by the spectrum of inert gases involved in the reaction.

Chemically active functional groups formed on the polymer surface allow practically any addition (copolymerization) reaction, and hydroperoxides carry out chemical cross-linking with the formation of covalent and hydrogen bonds. What is especially important in this process is that the hydroperoxide and peroxide groups are already “immobilized” (fixed) on the surface in the upper polymer layer. This is an indisputable advantage, especially when carrying out inoculation polymerization reactions according to the free radical mechanism. In this case, it is not required to use radical peroxides or azo initiators.

A comparative analysis of the IR spectra of samples of modified polyethylene (Figs. 3-4) showed the presence of a characteristic band of carboxyl groups (1726 cm ^-1 ), the quantitative determination of which was determined by chemical titration. The ozonized PE sample has a characteristic band of CH off-plane deformation vibrations (888 cm ^-1 ) at the RR ₁ C = CH ₂ group, however, the intensity of this band is several times lower than the intensity of such a band in the initial PE sample, since most vinylidene groups are ozonized consumed as a result of their interaction with ozone.

Figure 4 shows the IR spectra of modified PE with a complete decoding of the characteristic bands (cm ^-1 ):

719-721 - pendulum oscillations of CH ₂ groups

1302 - torsional vibrations of CH ₂ groups

1375-7 - fan vibrations of CH ₂ groups

1466-8 - deformation scissor vibrations of CH ₂ groups

1645 - stretching vibrations of C = O groups

1726 - stretching vibrations of C-UN carboxyl groups

1898 - overtone of the pendulum oscillations of the CH ₂ groups (731 + 1170)

2021 - overtone of pendulum and torsional vibrations of CH ₂ groups (720 + 1302)

2667 - overtone of fan and torsional vibrations of CH ₂ groups (1375 + 1302)

2846 - 50 - symmetric stretching vibrations of CH CH ₂ groups

2904 - 18 - asymmetric stretching vibrations of C-H CH ₂ groups

3662 — stretching vibrations of OH hydroxyl groups.

In addition, since not only the peroxide groups are immobilized or “anchored” on the activated surface, but also the other groups mentioned above, this makes it possible to “immobilize” other types of initiators, such as cationic, anionic, “stable free radicals” - nitroxides. This opens up great opportunities for the successful implementation of various mechanisms of grafting polymerization (grafting).

The surface-modified polymer powder 7 is mixed with a monomer (group of monomers) or polymer 8 in a high-speed planetary screw mixer 9, enters the hopper of the extruder 10, where it is copolymerized in the melt, with further granulation, passes through a vibrating screen and onto the packaging. In the extrusion line, a vacuum zone and a microadditive input zone may be provided.

As monomers, unsaturated mono- and polycarboxylic acids and their anhydrides, such as maleic, fumaric, itaconic, acrylic, methacrylic, polyacrylic acids, maleic, itaconic anhydrides, vinyl monomers: styrene, acrylonitrile, methyl acrylate, methyl , glycidyl methacrylate and other organosilicon compounds (silanes) such as vinyltrimethoxysilane, vinyltriethoxysilane, aminosilanes, glycidosilanes, mercaptosilanes and the like, as well as isocyanates, amines, sulfides, pheno s and others.

As polymers for the production of block copolymers, all types of polyolefins, polyamides, polyesters, polycarbonates, polystyrenes can be used, as well as copolymers: SAN (styrene acrylonitrile), ABS (acrylonitrile butadiene styrene), styrene thermoplastic elastomers and others, which add from 0.1 to 95 % by weight for copolymerization with the starting polymer by surface initiated melt polymerization in a twin screw extruder 10 with an L / D of at least 40, screw speeds from 300 to 500 rpm, at a temperature of from 130 to 230 ° C for synthesis and grafted graft and block copolymers 11 with a degree of grafting of at least 80%.

The main stages of surface-initiated polymerization:

- Modification of the polymer surface to form chemically active reactive groups (or "graft sites").

- "Immobilization" of the polymerization initiator on the surface of the polymer.

- Initiation of polymerization with chain growth from the “graft site” from the polymer surface.

The surface-initiated polymerization method has undeniable advantages in comparison with the standard grafting polymerization process based on chemical or physical sorption methods without the “immobilization” of the initiator. These benefits are as follows:

- High density grafting (polymer "brush").

- Controlled surface energy and surface chemistry.

- A wide selection of initiation methods: free radical, cationic, anionic, “living chains” mode, etc.

- The ability to synthesize innovative materials (graft and block copolymers, hybrids, nanomaterials)

Surface-initiated polymerization can be carried out on a screw-type mechanochemical device, in particular on a device selected from: a twin-screw extruder with unidirectional rotation of the screws, a twin-screw extruder with oppositely directed rotation of the screws, a twin-screw extruder with a set of cams of various types, for example, transport, locking, locking .

Measurement procedures

1. The number of grafted carboxyl groups in the copolymer was determined by a known method (US Pat. US No. 3862266, 1975 or US Pat. US No. 4506056).

The content of carboxyl groups in the modified polymer was determined by chemical titration according to the following procedure. -1.5 g of the grafted copolymer was placed in a 250 ml Erlenmeyer flask and the sample was dissolved in 75 ml of xylene with heating. Refluxed for 30 minutes. The solution was cooled to 75 ° C and 5 ml of standard 0.1 N KOH (excess) was added: Method No. 1 (in water), Method No. 2 (in isopropanol). Boiled for 45 minutes (for the saponification reaction), cooled and titrated the unreacted KOH - Method No. 1 (0.05N H ₂ SO ₄ in water), Method No. 2 (0.05N CH ₃ COOH in xylene) to an acidic medium using phenolphthalein ( change of pink color to colorless). For the calculation, the following equation was used:

where N ₁ , V ₁ - normality and volume of KOH,

N ₂ , Y ₂ - normality and volume of acid,

And the content of COOH groups in wt.%,

a - a sample of the polymer.

2. The degree of inoculation of maleic anhydride was determined by the following formula:

The degree of vaccination (%) = (a × 98 × 100) :( in × 45 × 2), where

a - the content of grafted carboxyl groups in the copolymer (in%),

in - the amount (in%) of MA in the initial reaction mixture,

98 - g mol of MA,

45 - g-mol of carboxyl group.

3. The number of peroxide groups in the modified samples was determined according to GOST 146183 -78.

0.2-2 g of the analyte (depending on the peroxide content) is weighed, the weighing result is recorded in grams to the fourth decimal place, placed in a flask, added with a cylinder of 10 cm ^{3 of} glacial acetic acid and 2 g of sodium bicarbonate are added. As soon as the emission of carbon dioxide bubbles ceases, the flask is closed with a stopper, placed in a dark place for 10-15 minutes and then 2 cm ^{3 of a} saturated solution of potassium iodide are poured. When determining hydroperoxides, the flask is placed in a dark place for 15-60 minutes (depending on the structure of the peroxide). Then, the contents of the flask are diluted with 50 cm ^{3 of} water and the iodine released is titrated with sodium thiosulfate solution using a starch solution as an indicator. In parallel, a control experiment is carried out.

The mass fraction of peroxide (X) in percent is calculated by the formulas for titration with 0.01 mol / dm ³ solution

where V is the volume of exactly 0.01 mol / dm ³ of a sodium thiosulfate solution spent on titration of iodine in a working experiment, cm ³ ;

V ₁ - the volume is exactly 0.01 mol / dm ³ of a sodium thiosulfate solution spent on titration of iodine in a control experiment, cm ³ ;

M is the molecular weight of peroxide;

m is the mass of the sample, g

4. The melt flow rate (MFR, g / 10 min) was determined on the IIRT-2 installation by forcing the polymer melt through a capillary with a diameter of B = 2.09-10 "m and a length of L = 8-10" ³ m at a temperature of 190 ° C and the load of 2.16 kg and 6.85 kg. The MFI value was calculated by the equation

MF = 600-M / t,

where t is the time interval between the sections of the bar (s), M is the mass of the bar (g). Indications were averaged over 5 values.

5. The strength of the adhesive bonds between the aluminum foil and the modified LDPE, as well as untreated LDPE (comparative example) was measured on Al-polymer-Al laminates pressed at 140 ° C and a pressure of 3-5 MPa according to a known method (US Pat. No. 4,550,556, 1985). Similar laminates are prepared on fabric and tested using the same procedure.

Physico-mechanical characteristics are determined on the samples in the form of blades pressed at a temperature of 180-200 ° C and a pressure of 3-6 MPa according to GOST 11262-80 (ST SEV 1199-78).

6. Determination of the degree of crosslinking of the polymer

Extraction of the non-crosslinked polymer was carried out with boiling o-xylene in a Soxhlet apparatus for 5 hours. Used 4 Soxhlet apparatus. Samples were cut into pieces of 5 × 5 × 3 mm and placed in bags of filtered paper (2 bags of each sample). Samples were air dried to constant weight.

7. Determination of gas permeability by oxygen

Samples of block copolymers were measured at room temperature (22-24 ° C) using an Ox-Tran 100 oxygen production instrument (manufactured in the USA).

In table 1, the numbers after the designations of the LDPE polyolefin indicate the duration of ozonation.

Table 2 shows the degree of grafting and adhesion strength for modified polyethylenes (examples 1-3), unmodified and by the known method of HDPE.

In table 3 - comparative data on the adhesive properties of the modified PP (example 4), unmodified PP and the known method.

Table 4 is a comparative table of physical and mechanical tests of the SAN copolymer "LURAN 378P" (unmodified and modified with EVA-b-SAN block copolymer (Example 5).

In table 5 - comparative data on testing silanol-grafted polyethylene (PEX-b) (example 15), unmodified PE and foreign analogues (Taborex).

Table 6 shows the comparative oxygen permeability test data for the HDPE-b-PVOH block copolymer (Example 6) compared to imported EVOH Soarnol (ethylene vinylalkolgol) oriented PET (Mylar) and polyamide 6 (Nylon 6 ").

The invention can be illustrated by the following examples.

Example 1-3

Synthesis of polyethylene-based graft copolymers by graft polymerization of maleic anhydride onto a polyolefin preactivated by reactive gases.

The following polyolefins were tested:

Linear LDPE 5118Q, LDPE 158, HDPE 277

Pre-crushed in an Avalong vortex mill 300 μm, powders of polyolefins in the amount of 50 kg were treated with an ozone-air mixture in a Graft-Polymer modifier reactor at a temperature of 25 ° C, a working gas pressure of 2.5 bar, and an ozonizer capacity of CFS-7 Ozonia 250 g O3 / hour, ozone concentration of 8 wt.%, For 10 minutes in the "fluidized bed".

Next, the activated powder was mixed with 1% by weight of maleic anhydride in a SPSh-50 planetary screw speed mixer for 10 minutes and the mixture was melt copolymerized in a CYKF twin-screw extruder with L / D = 40, screw diameter = 42 mm, at a screw rotation speed of 350 rpm with 11 temperature zones, with a process temperature of 130-220 ° C. The final reaction product was grafted copolymer granules containing up to 0.75% grafted carboxyl groups, with a grafting degree of at least 80%, see Tables 2, 3

Example 4

Synthesis of graft copolymer of polypropylene PP grade 01P by grafting polymerization of maleic anhydride on a pre-activated reactive gas PP.

A 50 kg propylene powder of grade 01P grade in the amount of 50 kg, preliminarily crushed in an Avalong vortex mill, was treated with an ozone-air mixture in a Graft-Polymer modifier reactor at a temperature of 25 ° C, a working gas pressure of 2.5 bar, and an ozonizer capacity of CFS-7 Ozonia "250 g O3 / hour, ozone concentration of 6 wt.% For 10 minutes in the" fluidized bed ".

Next, the activated powder was mixed with 1% by weight of maleic anhydride in a SPSh-50 planetary screw speed mixer for 10 minutes, and the mixture was melt copolymerized in a CYKF twin-screw extruder with L / D = 40, screw diameter = 42 mm at a screw rotation speed of 350 rpm with 11 temperature zones, with a process temperature of 180-250 ° C. The final reaction product was grafted granules of a graft copolymer with a grafting degree of at least 80%, see Tables 1, 2

Comparative data on the adhesive properties of the modified and unmodified polyolefins, as well as according to the known method (RF patent 2068421) are presented in table 2, 3.

Example 5

The synthesis of a block copolymer of ethylene vinyl acetate and styrene acrylonitrile EVA-b-SAN for SAN elasticization and hardening, preliminarily ground in a Avalong vortex mill 300 μm powder of sevylene (ethylene vinyl acetate) with a content of VA = 24-26% in an amount of 50 kg was treated with an ozone-air mixture Graft-Polymer modifier at a temperature of 25 ° C, a working gas pressure of 2.5 bar, a CFS-7 ozonizer productivity of 250 g O3 / hour, an ozone concentration of 8% for 10 minutes in a "fluidized bed".

Then, the activated powder was mixed with pre-ground 300 μm SAN (styrene acrylonitrile) powder in a SPSh-50 planetary screw mixer for 10 minutes in the ratio EVA / SAN = 90/10, and the mixture was melt copolymerized in a CYKF twin-screw extruder with L / D = 40, screw diameter = 42 mm, at a screw rotation speed of 350 rpm with 11 temperature zones, with a process temperature of 160-180 ° C.

The final reaction product is the block copolymer granules. Comparative results of physical and mechanical tests of the SAN copolymer “LURAN 378P” (unmodified and modified with the EVA-b-SAN block copolymer (“Graft-Polymer”) are given in Table 4.

Example 6

Synthesis of silanol-grafted polyethylene (PEX-b)

A powder of PEVP 276 grade polyethylene powder in the amount of 50 kg, preliminarily crushed in an Avalong vortex mill, 300 μm, was treated with an ozone-air mixture in a Graft-Polymer modifier reactor at a temperature of 25 ° C, a working gas pressure of 2.5 bar, and a CFS-7 ozonizer capacity Ozonium "250 g O3 / hour, ozone concentration of 6 wt.%, For 10 minutes in the" fluidized bed ".

Next, the activated powder was mixed with 2% by weight of vinyltrimethoxysilane in a SPSh-50 planetary screw speed mixer for 10 minutes, and the mixture was melt copolymerized in a CYKF twin screw extruder with L / D = 40, screw diameter = 42 mm, at a screw rotation speed of 350 rpm with 11 temperature zones, with a process temperature of 130-220 ° C. The final reaction product was granules of a silanol-grafted copolymer of polyethylene and VTMOS (vinyltrimethoxysilane). The resulting grafted copolymer together with various crosslinking catalysts (according to the Sioplas technology) was used to produce crosslinked polyethylene for hot water pipes. The degree of crosslinking corresponds to GOSTs for this type of product and is 65-75%, see table 5, which indirectly confirms the effectiveness of grafting VTMOS (vinyltrimethoxysilane) on polyethylene.

Example 7

Synthesis of a block copolymer with enhanced barrier properties based on HDPE grade 276 and polyvinyl alcohol grade BC-05 (manufactured in Taiwan)

Pre-crushed in an Avalong vortex mill 300 microns, PEVP 276 polyethylene powder in an amount of 50 kg was treated with an ozone-air mixture in a Graft-Polymer modifier reactor at a temperature of 25 ° C, a gas working pressure of 2.5 bar, a CFS- ozonizer capacity 7 "Ozonium" 250 g O3 / hour, ozone concentration of 6 wt.% For 10 minutes in the "fluidized bed".

Then, the activated powder was mixed with 80% by weight of polyvinyl alcohol with a hydrolysis degree of 74 mol% of grade BC-05 (Taiwan) in a SPSh-50 planetary screw screw mixer for 10 minutes, and the mixture was melt copolymerized in a CYKF twin screw extruder "With L / D = 40, screw diameter = 42 mm, at a screw rotation speed of 350 rpm with 11 temperature zones, with a process temperature of 130-220 ° C. The final reaction product was granules of a block copolymer of high density polyethylene with polyvinyl alcohol (HDPE-b-PVOH).

The resulting block copolymer was tested for oxygen permeability in comparison with imported EVOH Soarnol (ethylene vinylalkolgol) oriented PET (Mylar) and polyamide 6 (Nylon 6), see table 6.

A comparative analysis of the data on the examples according to the invention, comparative examples and the known method confirms the achievement of a new technical result in obtaining modified polymers of the claimed method.

The technical result was achieved due to the innovative industrial technological scheme and process parameters of gas-chemical modification and synthesis of grafted copolymers. At the same time, it was possible to significantly increase the safety and environmental friendliness of the process, which is obvious from the hardware design of the technological scheme and the parameters and design features of the equipment used.

Examples illustrating the use of the invention directly and indirectly show that it was possible to significantly expand the range of monomers and polymers used for the production of graft and block copolymers, as well as to increase the degree of grafting of the monomer and compatibilization of the components of block copolymers

Table 1 Example Ozonation time, min The number of peroxide groups, wt.% PTR 1. LDPE-10 10 0.34 0.94 2. LDPE-20 twenty 0.35 0.77 3. LDPE-30 thirty 0.33 0.64

table 2 Example 1-3 The number of carboxyl groups,% with the initial MA - 1 weight% The degree of vaccination,% Adhesion strength, g / cm width A1 the cloth LDPE 51180 0.78 85 750 3500 LDPE 158 0.76 82.7 720 3400 HDPE 277 0.74 80.5 700 3200 Comparative Unmodified. - twenty 800 By a known method 24 500 2500

Table 3 Example 4 The number of carboxyl groups,% with the initial MA - 1 wt.% The degree of vaccination,% Adhesion strength to A1 g / cm width PP-01P 0.73 80 900 Comparative Unmodified - 40 By a known method 33 720 Table 4 No. p / p The name of indicators Test Results: SAN copolymer "Luran378P", Germany ave. SAN copolymer modified "Luran378P" + l% EVA-b-SAN one. Melt flow rate, g / 10 min. At Т = 220 ° С / 10 kg 17,2 21.0 2. The tensile strength, kgf / cm ² 235.4 353.4 3. Relative extension, % 2.2 2.6 four. Charpy impact strength without notch, kgf * cm / cm ² 21.0 22.1 5. Charpy impact strength notched, kgf * cm / cm ² 2,8 2,8 6. Charpy impact strength with notch (at T-20 ° C), kgf * cm / cm ² 2.7 2.5 7. Notched Izod Impact Strength, kJ / m ² 2.1 2,3 8. Izod impact strength with notch (at Т = -20 ° С), kJ / m ² 1,6 2.0

Table 5 Example 6 Gel fraction% Package weight, g Sample weight before washing, g Weight arr. + Bag after washing, g Weight of sample after washing, g HDPE 276 Arr 1 1.0180 0.7175 1.5613 0.5433 75.7 HDPE 276 Arr 2 0.9878 0.6435 1.4754 0.4876 75.7 HDPE 276 Arr 3 0.9750 0.7038 1.5118 0.5368 762 HDPE 276 Arr 4 1.0387 0.654 1.5285 0.4898 74.8 Nemodif HDPE 0 0 Comparative PEX (imp.) 1.0148 0.5975 1.3308 0.316 69.7

Table 6 Example 7 Ratio of components Permeability to oxygen (ss-ml / .m2 at 1 atm ASTMD-3985-81 HDPE-b -PVOH) 0/100 03 Measurements at room temperature 22-24 ° C 20/80 0.36 30/70 0.42 Comparative EVOH ("Soarnol") - 0.35 Comparative PET ("Mylar") - 33 Comparative Polyamide 6 ("Nylon 6") - 33

Claims (5)

1. A method for the industrial production of modified polymers, in which a pre-ground polymer is subjected to fluidized gas chemical modification using reactive gases including inert gases and ozone as an oxidizing gas, and the resulting activated powder is mixed with a monomer or group of monomers or polymer with their subsequent copolymerization by surface initiated polymerization in a melt in an extruder, characterized in that the gas-chemical modification carried out they melt at a temperature of no higher than 30 ° C and at an ozone concentration of 5-15 wt.% with a jet of reactive gases for 10-30 minutes, and the polymerization in an extruder is carried out at a temperature of 130-230 ° C, at a screw speed of 300-500 rpm / min, L / D at least 40, for the synthesis of grafted grafts and block copolymers with a degree of grafting of at least 80%. 2. A device for implementing the method of industrial production of modified polymers according to claim 1, comprising a polymer powder shredder, a gas modification reactor for the ground polymer powder, and an extruder for melt polymerization of the activated polymer powder with a monomer (or group of monomers) or a polymer, characterized in that equipped with a unit for preparing a mixture of reactive gases with an ozone generator from air, the reactor is made with an inlet at the bottom for reactive gases and an outlet at the top, p When in use, it is installed downstream of the reactor for the catalytic decomposition of ozone destructor, and cross-sectional area than the cross sectional entry, and a twin-screw extruder is configured with a L / D of not less than 40 and with a screw speed of 300-500 rev / min. 3. The device according to claim 2, characterized in that an exhaust fan is installed at the outlet of the reactor. 4. The device according to claim 2, characterized in that the chopper is made in the form of a rotary vortex mill with a magnetic separator and with a rotor speed of at least 3000 rpm. 5. The device according to claim 2, characterized in that the installation for preparing a mixture of reactive gases is made with the possibility of preparing an ozone-air mixture and with a device for cooling and drying air.

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