RU2433082C2 - Method to produce polymer compositions based on micro- and nano-disperse ceramic powders - Google Patents

Abstract

FIELD: nanotechnologies.

SUBSTANCE: invention relates to the method of production of polymer compositions on the basis of micro- and nano-disperse ceramic powders for modification of polymers. The method includes production of composite powders, joint treatment of polymer and ceramic powders in planetary, centrifugal or vibratory-centrifugal activators for 10-60 sec with energy input by balls with capacity of around 100 W/g. Polymers are polyolefines and polyamides. Produced highly-concentrated compositions may be used as master batches for modification of polymers, and compositions with low concentrations of inorganic additives (up to 10 wt %) may be used to directly produce films and plates.

EFFECT: items have improved barrier and physical and mechanical properties and lower prime cost.

7 dwg, 5 tbl

Description

The invention relates to methods for producing polymer compositions with improved barrier and physico-mechanical properties based on polyolefins, polyamides and micro-, nanosized ceramic powders.

Three main methods / techniques for mixing polymers with nanoparticles, which are actively used in the polymer industry in the last decade, are distinguished:

1) dispersion in solutions;

2) co-polymerization in situ;

3) melt mixing.

Polar polymers are easily mixed with nanoparticles in all three ways, and for non-polar or slightly polar, such as polyolefins, the second method is preferable, although there are successes in the preparation of these composites by other methods.

Using in-situ polymerization, nanocomposites of polyamide-6 and nanolayer silicates with improved thermal and physico-mechanical properties, as well as polyethylene and polystyrene, were obtained.

The third melt mixing method is very common because of its apparent simplicity and ease of industrial introduction. This method is used to mix polyethylene oxide with nanosilicates at 80 ° C for 6 hours, polystyrene, polypropylene, biodegradable polylactides, maleic anhydrides, high density polyethylene and a copolymer of ethylene with vinyl acetate and nanomontmorillonite. The best results were obtained with a 2-stage high-speed twin-screw extruder mixing using surfactants.

The mixing of hydrophobic matrices of polymers, such as polyolefins with hydrophilic particles in this way is complicated by poor dispersion and adhesion of hydrophilic nanoparticles in hydrophobic polymer matrices, on the one hand, and the tendency of nanoparticles with high surface energy to agglomerate, on the other.

Typically, polymers are reinforced with nanoparticles in an amount of 2-6 wt.%, Although nanocomposites with a high percentage of nanoparticles have been developed (master batches of polyolefins with nanoparticles of calcium carbonate, titanium and silicon oxides up to 70%).

The properties of the obtained two-phase composites are determined by two main factors:

1) dispersion and distribution of nanoparticles in the polymer matrix;

2) the interaction between polymer chains and nanoparticles.

The first is key to ensuring the barrier properties of packaging materials, and the second is to increase the physico-mechanical properties of packaging. It is the special structure of the distribution of nanoparticles in the polymer matrix and the interfacial boundaries that make nanocomposites different from ordinary polymer composites, adding unique properties even with such a small content of nanoparticles as 2-6 wt.% In the composite.

In addition to research in the field of creating nanocomposites (NCs) based on polar polymer matrices, many works are also devoted to modifying the properties of nonpolar polymers, and first of all the most widely used polyolefins in industry and households, the world production of which makes up more than half of all plastics produced in the world. However, to date, nanocrystals with nonpolar or weakly polar polymers do not possess such high performance characteristics as materials based on polar polymers. First of all, this is due to the fact that the surface of natural layered silicates is hydrophilic, which makes it difficult to ensure a high level of combination of polymer and filler. The ability of polymers to intercalate into clays having different layer structures has not been studied enough [1].

Numerous methods for producing nanocomposites [2-11] involve the use of one or more exfoliating additives, complex methods for introducing inorganic particles into a melt or solution, the obligatory preparation of an inorganic nanosupplement / organic modifier preliminary composite, and complex multicomponent compositions.

Known "dry" methods for producing polymer modifiers.

In the method RU 2332398 C1 (publ. 27.08.2008) [12] receive zirconium carboxylates by the interaction of zirconium tetrachloride with organic substances in the solid phase in the absence of solvent. The mechanical activation of the mixture is carried out using an eccentric ball vibratory mill (operating frequency 5-50 Hz, amplitude 5-20 mm) and various devices for dispersing solid materials with an energy intensity of 0.5-100 kW / kg: vibration ball, bead, planetary, impact abrasive, coffee mills, disintegrators, extruder mixers. The processing time in the apparatus is from 15 minutes to 3 hours. The method is limited to one inorganic component in the composition of the composite, and subsequent extraction of the resulting zirconium carboxylate with an organic solvent is necessary.

In [13] (G.E. Selyutin, V.A. Voroshilov, Yu.Yu. Gavrilov, V.A. Poluboyarov, Z.A. Korotaeva, V.A. Zakharov, V.E. Nikitin, D.V. . Tsupinin. Changes in the wear resistance of ultra-high molecular weight polyethylene plates when modified by mechanically activated ceramic nanopowders // Chemical Technology, 2009, No. 7, p. 422), a method for introducing mechanochemically activated ceramic powders into ultra-high molecular weight polyethylene (UHMWPE) with a molecular weight of up to 8 × 10 ⁶ .

A mixture of nano- and ultrafine inorganic powders and polymer (UHMWPE) was subjected to processing in planetary activators with energy introduced by balls into a material with a power of about 100 W / g, the processing time in activators was 1-5 minutes. The modifier obtained in this way was mixed with a polymer (UHMWPE) in a mixer, and then products — plates — were obtained by hot pressing.

The amount of inorganic powders in the final polymer product was varied in the range of 1-15 wt.%.

It was found that the introduction of crystalline fillers with sizes less than one 0.1 μm in UHMWPE leads to a significant increase in abrasion resistance. The optimal concentration of the filler is in the range of 5-10 wt.%, While the abrasion resistance increases many times (sometimes 1000 times).

A disadvantage of the known method is that only ultra-high molecular weight polyethylene was subjected to the modification process, a modifier (a mixture of polymer and inorganic additive) was prepared beforehand, which was then added to the bulk of the polymer, the modification was carried out in order to improve abrasion resistance.

The closest technical solution selected for the prototype is a method for producing polymer compositions based on micro- and nanosized ceramic powders for polymer modification ([14] DE 19958197 (A1) Polymercompound, dessen Herstellung und verwendung, sowie daraus hergestellter Sinterkörper) (publ. 15.06. .2000), in which a polymer compound is obtained with a ceramic powder content of more than 5% by volume (or more than 12.4-24.2 mass%, depending on the composition of the powder).

The process of obtaining a polymer compound includes two stages: first, a dense preliminary composite is obtained, which contains 40-50 volume% (more than 80 wt.%) Of ceramic powder from the polymer compound, then it is diluted with thermoplastics (which are used as polyolefins, polyesters, polyamides) . Ceramic powder with a specific surface area of more than 1.8 · 10 ⁸ m ² / m ³ includes metal oxides, carbides, nitrides or mixtures thereof (ZrO ₂ , Al ₂ O ₃ , SiO ₂ , TiO ₂ , Y ₂ O ₃ , MgO). Upon receipt of the preliminary composite, various dispersants are used (carboxylic acids, chlorosilanes, alkyl amines) and a mixer with a power of 50-350 watts with a maximum torque of 70-440 Nm is used, the mixing time is from 80 minutes to 3 hours.

The disadvantage of this method is that it involves two stages of obtaining a polymer compound, a rather long mixing time in the mixer and the use of dispersants and solvents in the preparation process. The problem solved by the claimed technical solution is to

- simplifying the method of producing polymer compositions based on micro- and nanodispersed ceramic powders by reducing the stages of preparation,

- the rejection of the use of dispersants and solvents, which makes the method more environmentally friendly,

- expanding the range of concentrations of inorganic additives used (from 0.01 to 70 wt.%),

Compared with the existing level of technology, the claimed method allows:

- accelerate the dispersion of ceramic powders in the polymer (from several seconds to 1 minute compared to several hours),

- more evenly distribute inorganic additives in the polymer matrix, without the use of additional dispersing agents,

- accelerate the extrusion processes (for mixtures that have undergone mechanochemical processing, as a rule, one run through the extruder is sufficient).

The problem is solved due to the fact that in the inventive method for producing polymer compositions based on micro- and nanodispersed ceramic powders for polymer modification, polyolefins and polyamides are used as polymers, composite powders are obtained by joint processing of a mixture of polymer and ceramic powders in planetary, centrifugal, vibrocentrifugal activators for 10-60 seconds when introduced by balls (grinding bodies) into the energy material with a power of about 100 W / g with the following ratios of components, wt .%:

polymer - 30 ÷ 99.99 ceramic powders - 0.01 ÷ 70.

The salient features of the claimed technical solution:

- polyolefins and polyamides are used as polymers;

- processing a mixture of polymer and micro-, nanosized ceramic powders is carried out in planetary, centrifugal, vibrocentrifugal activators;

- the treatment is carried out for 10-60 seconds when introduced by balls (grinding bodies) of energy into the material with a power of about 100 W / g;

- processing is carried out at the following ratios of components: polymer - 30 ÷ 99.99 wt.%, ceramic powders - 0.01 ÷ 70 wt.%.

The above set of essential distinguishing features allows us to solve the problem and is not known from the existing level of technology, which allows us to conclude that the claimed technical solution meets the criteria of "inventive step" and "novelty."

Achievable technical result consists in obtaining concentrated compositions (5-70 wt.% Ceramic powders), which can be used as master batches for polymer modification, and in obtaining compositions with low concentrations of ceramic powders (0.01-10 wt.%), Which can be used for direct production of films and plates. Products have improved barrier and physico-mechanical properties and lower cost. Since the method allows not to use additional dispersing agents and solvents, then, in the end, it is environmentally friendly.

The implementation of the proposed method.

As the polymer component of the composite (polar and nonpolar) were selected:

1) non-polar high pressure polyethylene brand LLDPE 6101 RQ;

2) polar polyamide brand MXD6 / Nylon

and ceramic powders indicated in table 1 (No. 1-6).

Composite powders were obtained by joint processing of the mixture in planetary and centrifugal (vibrocentrifugal) activators. The ratio of the amount of polymer ranged from 30 to 99.99, and inorganic additives from 0.01 to 70 wt.%.

Table 1 also shows the processing conditions of the mixtures upon receipt of the composites. In the claimed solution, the processing time in the activators is 10-60 seconds, the minimum amount of inorganic additives is 0.01 wt.% (0.002 vol.%), Which is significantly less than in the known solutions (No. 7-9) (Table 1).

Table 1 The conditions for the preparation of composites and the content of inorganic components No. Ceramic powders S _beats , m ² / g Standard average particle size The average particle size calculated by S _beats The amount of inorganic additives Mixer Processing Conditions Sample Trademark mass% volume.% The claimed technical solution one TiO ₂ TR-92 (rutile) CAS 13463-67-7 (Titanium Dioxide Pigments) 17.1 ~ 3 μm ~ 80 nm 0.01-70 0.002-36 10-60 seconds planetary or centrifugal (vibrocentrifugal) activators; energy introduced into the material with a power of the order of ~ 100 W / g 2 TiO ₂ R-FC5 (rutile) (for polymers) 6.8 0.18 μm ~ 200 nm 0.01-70 0.002-36 3 Na-B Bentonito-
foundry powder GOST 28177-89 grade П1Т1 17.4 ≤1 μm 0.01-50 0.004-25 four CaCO ₃ GOST4530-76 3.5 ~ 630 nm 0.01-70 0.004-46 5 Rosil-175 (SiO ₂ ) TU 2168-038-00204872-2001 155 ~ 17 nm 0.01-20 0.004-10 6 SiC 5.5 ~ 340 nm 0.01-70 0.003-42

Continuation of table 1 No. Ceramic powders S _beats , m ² / g Standard average particle size The average particle size calculated by S _beats The amount of inorganic additives Mixer Processing Conditions Sample Trademark mass% volume.% (Prototype) DE 19958197 (A1) Polymercompound, dessen Herstellung und Verwendung, sowie daraus hergestellter Sinterkörper one Oxides, nitrides, carbides or mixtures thereof Stage 1 40-50 80 minutes - 3 hours mixer with a power of 50-350 watts, maximum torque of 70-440 Nm Obtaining a preliminary dense composite 2 stage ≥5 Thermoplastics composite dilution (Example 1) G.E.Selyutin et al. // Chemical Technology, 2009, No. 7, p. 422 2 Carbides, oxides, silicates ≤0.1 μm 1-15 wt.% up to 5 min planetary activators. The energy introduced into the material, with an intensity of the order of ~ 100 W / g (Example 2) RU 2332398 C1 Method for the production of zirconium carboxylates 3 ZrCl ₄ Stage 1 ZrCl ₄ : RCOOM at a molar ratio of 1 <m <4.5 15 min - 3 hours eccentric ball vibratory mill, vibratory ball, bead, planetary, attrition abrasion, coffee mills, disintegrators, mix extruders with a power of 0.5-100 W / g Preparation of Zirconium Carboxylates in the Solid Phase 2 stage Subsequent extraction of the resulting zirconium carboxylate with an organic solvent

According to x-ray phase analysis (XRD), the coherent scattering region (CSR) of the CaCO ₃ , TiO ₂ phases in the obtained composite powders was about 30–40 nm.

Further, to obtain films, the initial concentrated powder composite was mixed in an extruder with a polymer to achieve concentrations at which the required fluidity of the mixture was achieved or diluted mixtures of polymer and ceramic powders were obtained directly in the activators, from which products were also further prepared. Physico-mechanical and barrier properties of films with a thickness of 500 μm based on polyethylene, polyamide and the amount of inorganic additives are given in table 2.

The data of scanning electron microscopy (SEM) of films based on polyethylene and additives SiO ₂ (0.1-5%), TiO ₂ (0.1-5%), Na-montmorillonite (5%), CaCO ₃ (5%) are shown in Fig. 1 -four.

The data of SEM and atomic force microscopy (AFM) films based on polyamide and additives TiO ₂ (0.1-1%) are shown in figure 5-7.

Plates with a thickness of 1 mm were made by hot pressing. The properties of the plates and the amount of inorganic additives are given in table 3.

Compared with the original polymer (sample 1, table 2), the gas permeability of films based on polyethylene (at 50% RH and 23 ° C) drops by 27-34% for samples containing 5 wt.% Ceramic powders (samples 4-7). For samples containing ceramic powders in an amount of from 1 to 0.01 wt.%, Gas permeability is reduced by 30-56% (samples 8-13). Strength characteristics are improved up to 15%.

The elastic modulus increases to 40-60% with an inorganic content of 0.01-1 wt.%, Up to 24-28% for 5 wt.%, Up to 55% for 10 wt.% SiO ₂ , up to 44% for 25 wt.% TiO ₂ .

A film based on polyethylene with various additives according to the claimed method, compared with the analog film available on the market with the addition of nanodispersed clay Nanomax, manufactured by USA (sample 14), exhibits lower oxygen permeability and higher physical and mechanical properties.

The gas permeability of films based on polyamide decreases several tens of times for samples containing 0.1-1 wt% TiO ₂ (samples 16, 17) compared with the initial sample (15).

A film based on polyamide with TiO ₂ additives according to the claimed method exhibits a similar oxygen permeability compared to a film similar to that available on the market with the addition of Imperm nanodispersed clay, manufactured in USA (sample 18), but has a significantly lower cost (1.5-5 times) .

For all samples of plates (table 3) containing additives TO ₂ from 0.05 to 50 wt.% (Samples 2-6), the tensile strength at break is slightly increased in the range of 12.7-16.8%;

the elastic modulus increases within 1.28-2 times compared with the original sample 1;

strength at 10% deformation increases in the range of 12.7-14.7%;

gas permeability decreases in the range of 19.6-34.3%.

For plate samples containing CaCO ₃ additives from 0.05-20 wt.% (Samples 7-11), the tensile strength increases in the range 12.7-16.8%; a sample with a content of 50 wt.% CaCO ₃ (sample 12) is less durable by 8.1-25.7% than the original sample;

the elastic modulus increases within 1.2-2.2 times in comparison with the original sample 1;

strength at 10% deformation increases in the range of 11.1-15.0%;

gas permeability with a content of 0.1 wt.% CaCO ₃ ) decreases in the range of 26-35%, with a content of 20 wt.% CaCO ₃ - by 28.7%.

For samples of plates containing additives of SiO ₂ from 0.05-20 wt.% (Samples 13-17), the tensile strength increases in the range 0-27.9%;

the modulus of elasticity increases within 1.32-2.04 times;

strength at 10% deformation increases in the range of 14.1-20.3%;

gas permeability decreases in the range of 16.8-25% for samples with an additive content of up to 5 wt.%.

To evaluate the effectiveness of the mechanochemical method of mixing, plates were made of composites prepared in an activator (processing time 20-60 seconds at 60 g, g - gravity acceleration, a parameter that determines the energy intensity of the activator) and in a simple mixer (processing time 30 seconds).

Comparative evaluations of the density and gas permeability of the plates were made. The density of plates made from mechanical composite mixtures with the same additive content is always lower than the density of plates made from composite powders obtained by mechanochemical treatment in activators (table 4).

A mechanochemical method for producing a composite material, involving the combined processing of polymer and ceramic powders in activators, is more effective than other mixing methods, since it allows one to obtain samples of higher density than with simple mechanical mixing. And this determines the improvement of some properties, for example, a decrease in the gas permeability of the plates by more than two; samples prepared by mixing the polymer with inorganic additives in the mixer give a decrease in oxygen permeability of no more than 11.2%, and samples prepared by mixing in the activator AGO-3 give a decrease in oxygen permeability up to 28.7% (table 5, samples 1 and 2). It is known that the higher the density of the polymer, the lower the gas permeability and the better the mechanical characteristics of the polymer [15].

Table 5 The dependence of the oxygen permeability of plates based on polyethylene on the method of mixing the starting components No. Processing, s Ceramic powders Decrease in O-penetration value,% Mixing method Quantity, wt. % Structure one twenty twenty CaCO ₃ 28.7 Activator 2 thirty twenty CaCO ₃ 11.2 Mixer 3 twenty 5 SiO ₂ 16.8 Activator four thirty 5 SiO ₂ 5.6 Mixer 5 twenty 5 TiO ₂ 19.6 Activator 6 thirty 5 TiO ₂ 7.7 Mixer 7 twenty twenty TiO ₂ 34.3 Activator 8 twenty 5 SiC 23.1 Activator 9 thirty 5 SiC 9.8 Mixer

It was determined that the upper limit of the concentration of ceramic powders in polymers for creating masterbatches is 70 mass% for titanium dioxide, 50-70 mass% for calcium carbonate, 30-40 mass% for sodium montmorillonite, and Rosil brand silicon dioxide -175 - 20 wt.%.

As the above amounts of additives increase, the strength of the masterbatches drops sharply, as the polymer becomes insufficient to cover the surface of inorganic particles.

With a decrease in the concentration of additives below 0.01 mass%, the effect of modification decreases.

For extrusion of films without masterbatches, the concentration of ceramic additives up to 5-10 wt.% Is optimal.

Compared with the prototype, the inventive method allows to obtain highly concentrated compositions that can be used as masterbatch for polymer modification, compositions with low concentrations of ceramic powders (up to 10 wt.%) Can be used to directly produce films and plates. Products have improved barrier and physico-mechanical properties, and are also obtained with lower (1.5-5 times) cost compared to the prototype and similar materials on the market.

Literature

1. Gerasin V.A., Bakhov F.N., Merekalova N.D., Korolev Yu.M., Zubova T.L., Antipov E.M. // The effect of the structure of the modifier layer on the compatibility of polymers with modified montmorillonite. Engineering Physics Journal. 2005.V. 78. No. 5. S.35.

2. United States Patent Application 20090029167 Polymer nanocomposites including dispersed nanoparticles and inorganic nanoplatelets.

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9 RU 2325411 C2. The method of obtaining polyolefin nanocomposites.

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12. RU 2332398 C1. A method of producing zirconium carboxylates (publ. 27.08.2008). Example 1

13. G.E.Selyutin, V.A. Voroshilov, Yu.Yu. Gavrilov, V.A. Poluboyarov, Z.A. Korotaeva, V.A. Zakharov, V.E. Nikitin, D.V. Tsupinin. Changes in the wear resistance of ultra-high molecular weight polyethylene plates when modified with mechanically activated ceramic nanopowders // Chemical Technology, 2009, No. 7, p. 422. Example 2

14. DE 19958197 (A1) Polymercompound, dessen Herstellung und Verwendung, sowie daraus hergestellter Sinterkörper (publ. 06/15/2000). Prototype.

15. S.A. Reutlinger. Permeability of polymeric materials. M., Chemistry, 1974, 272 p.

Claims (1)

A method of producing polymer compositions based on micro- and nanodispersed ceramic powders for polymer modification, including the production of composite powders, characterized in that polyolefins and polyamides are used as polymers, the mixture of polymer and ceramic particles is processed in planetary, centrifugal or vibration-centrifugal activators for 10-60 s with the energy introduced by the balls into the material with a power of about 100 W / g with the following ratios of components, wt.%:
polymer 30 ÷ 99.99 ceramic particles 0.01 ÷ 70

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