RU2596041C1 - Polymeric nanocomposition for effective protection against uv radiation - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to polymeric nanocompositions intended for obtaining film materials that provide protection against UV radiation and photochemical ageing. Composition contains polyolefin or a olefin copolymer and UV-absorber. UV-absorber is nanosized silicon carbide that is single-phase polycrystalline and consisting of synthetic silicone carbide (SiC) with structure of moissanite polytype 6H with average particle size 34±3 nm in the amount of 0.1-1.5 wt%. Polymeric nanocomposition enables to obtain film materials with wide spectral range of absorption wave UV radiation (200-420 nm).

EFFECT: dangerous UV radiation range (200-290 nm) is absorbed at 100-90 %.

1 cl, 1 tbl

Description

The invention relates to polymeric film materials that protect against UV radiation and photochemical aging.

Known polymer film material for enclosing greenhouses, obtained from a composition comprising high pressure polyethylene or a copolymer of ethylene with vinyl acetate in an amount of 99.0-99.2 wt. % and benzene OA in an amount of 0.8-1.0 wt. % [patent 94027744, Russia, IPC C08J 5/18, C08L 23/06, publ. 06/20/1996].

The disadvantage of this invention is the relatively narrow spectral range of absorption of UV radiation (290-330 nm), high spectral transmittance for UV (up to 15%) and the technologically unsuccessful stage of preliminary cold mixing of UV absorber powder with polymer granules, which gives a poor distribution of particles in the polymer film compared to the present invention.

Known polymer composition that protects against the penetration of UV radiation, including an organic thermoplastic polymer material, preferably a polyolefin in an amount of 981 or 985 g, an oligoester or polyester of the claimed formula in an amount of 13 g and micronized zinc oxide in an amount of 6 g or micronized titanium dioxide in an amount 2 g. A linear low-density polyethylene with a density of 0.919 g / cm ³ and a melt flow index (190 ° C, 2.16 kg) of 1.1 was used as the polyolefin. The mixture is extruded at 230 ° C. on a twin screw extruder. The obtained granules are blown (using a laboratory blown extruder) at 230 ° C and get a film with a thickness of about 50 μm [patent 2370502, Russia, IPC C08G 63/685, C08K 5/10, C08K 5/3492, publ. 07/10/2007].

The disadvantage of this invention is the relatively narrow UV transmission range (280-390 nm) and higher spectral transmission (from 9.9 to 91.0%).

The closest set of essential features to the claimed material is a polymer composition for protection against UV radiation, which contains as a polymer matrix a polyolefin or olefin-based copolymer (high pressure polyethylene (LDPE), melting point (max) 104 ° C, melt index 2.0 g / 10 min, density 0.91 g / cm ³ , molecular weight 20000-24000; ethylene vinyl acetate copolymer (SEVA), vinyl acetate content 20-30 wt.%, Melting point 70-85 ° C, melt index 20-80 g / 10 min, density 0.93-0.95 g / cm ³ ; low polyethylene o pressure (HDPE), melting point (max) 114-120 ° C, melt index 1.5-3.0 g / 10 min, density 0.93 g / cm ³ , molecular weight 25000-30000; polypropylene (PP) , melting temperature (max) 140-145 ° C, melt index 3.0 g / 10 min, density 0.85 g / cm ³ ) and the active substance is polydispersed nanocrystalline silicon with a specific surface area of 36-97 m ² / g, encapsulated into the shell of oxide, silicon dioxide or their phase of variable composition of nitride, silicon oxynitride or their phase of variable composition, characterized by a directionally variable distribution function over Dimensions of the core particles nanocomposite material [Patent 2429189 C1, Russia, IPC V82V 1/00, C08L 23/02, C08K 3/02, C08J 5/18, publ. 09/20/2011. Tutorsky I.A., Belogorokhov A.I., Ischenko A.A., Storozhenko P.A. The structure and adsorption properties of nanocrystalline silicon // Colloidn. Journal 2005, v. 67, No. 4, p. 541-547. Bagratashvili V.N., Belogorokhov A.I., Ishenko A.A., Storozhenko P.A., Tutorsky I.A. Control of the spectral characteristics of multiphase ultrafine systems based on nanocrystalline silicon in the UV wavelength range // DAN. 2005, t. 405, No. 3, p. 360-363. Olkhov A.A., Liao D.J., Fetisov G.V., Goldstrakh M.A., Kononov N.N., Krutikova A.A., Storozhenko P.A., Ischenko A.A. Nanocomposite films with UV protective properties based on polyethylene with ultrafine silicon // Plastics. 2010, No. 9, p. 40-46].

The disadvantage of this invention is the insufficiently high level of absorption of the dangerous range of UV radiation (200-290 nm) (from 80 to 90%) and the relatively low values of the strength of the films at break compared with the present invention.

The technical result of the invention is the creation of a film material based on a polyolefin or a copolymer of olefin and nanosized silicon carbide with an extended spectral range of absorption of medium-wave UV radiation (200-420 nm) and the absorption of a range of UV radiation (200-290 nm) dangerous for biological objects per 100 -90%, with increased strength (from 19 to 23 MPa for films based on LDPE).

The specified technical result is achieved due to the fact that in the polymer matrix of the polyolefin or olefin-based copolymer (high pressure polyethylene (LDPE), melting point (max) 104 ° C, melt index 2.0 g / 10 min, density 0.91 g / cm ³ , molecular weight 20000-24000; ethylene vinylacene copolymer (SEVA), vinyl acetate content 20-30 wt.%, melting point 70-85 ° C, melt index 20-80 g / 10 min, density 0.93- 0.95 g / cm ³ ; low pressure polyethylene (HDPE), melting point (max) 114-120 ° C, melt index 1.5-3.0 g / 10 min, density 0.93 g / cm ³ , molecule unit mass 25000-30000; polypropylene (PP), melting point (max) 140-145 ° C, melt index 3.0 g / 10 min, density 0.85 g / cm ³ ) the active substance is introduced - nanosized silicon carbide, which is single-phase polycrystalline and consisting of synthetic carborundum (SiC) with the structure of moissanite polytype 6H with an average particle size of 34 ± 3 nm in an amount of 0.1-1.5 wt. %

A method of obtaining the inventive polymer film material includes hot mixing granular polymer in an amount of 98.5-99.9 mass. % and nanosized silicon carbide 0.1-1.5 mass. % at 120-130 ° C for a copolymer with vinyl acetate, 140-150 ° C for high pressure polyethylene, 160-170 ° C for low pressure polyethylene, 170-180 ° C for polypropylene and 160-180 ° C for polymer blends over 5-10 minutes until a homogeneous mixture is formed, or a superconcentrate containing 5-15 wt. % nanosized silicon and 95-85% polymer or polymer mixture under the same conditions. Then the composite material is heated to 200-230 ° C for a mixture with polypropylene, 190-210 ° C for a mixture with low pressure polyethylene and polymer compositions, 170-190 ° C for a mixture with high pressure polyethylene and 130-140 ° C for a copolymer mixture ethylene with vinyl acetate and form the film by melt extrusion.

The technical result provided by the claimed invention of a film polymeric material is expressed in the reduction of the spectral transmission of the material in the zone of UV radiation hazardous to biological objects (200-290 nm) from 90 and almost to 100% when particles of nanosized silicon carbide are introduced into the polymer in an amount of 0, 1-1.5 wt. % (with a film thickness of 50-100 microns).

Examples of the invention.

Example 1

Preliminary hot mixing of granular high pressure polyethylene (LDPE) in an amount of 99.0 and nanosized silicon carbide in an amount of 0.1 wt. % in the mixer open (rollers) or closed type (twin screw extruder, cam mixing chamber) for 5-10 minutes until a homogeneous mixture is formed. Mixing is carried out at temperatures from 140 to 150 ° C. The prepared mixture is granulated and then fed to the extruder to obtain a flat or tubular film. The temperature conditions of film formation at the ARP-20-25 extrusion plant (Russia) are in the range of 170-190 ° C.

Example 2

Analogously to example 1, only the content of nanosized silicon carbide of 0.5%.

Example 3

Analogously to example 1, only the content of nanosized silicon carbide 1.0%.

Example 4

Analogously to example 1, only nanosized silicon carbide is taken in an amount of 1.5%.

Example 5

Analogously to example 4, only a copolymer of ethylene with vinyl acetate was taken as a polymer.

Example 6

Analogously to example 4, only polypropylene is selected as the polymer.

The values of the integral transmittance in the region of 200-290 nm and strength characteristics of the samples are shown in the table.

Mechanical Testing Procedure

For mechanical tests, tensile samples were cut out of the films under tension using a special cutting device in the form of strips 10 mm wide and 50 mm long. To determine the tensile strength at break (MPa), the universal tensile testing machine UTS-211 (Germany) was used. The speed of movement of the clamps is 100 mm / min, the distance between the clamps is 30 mm. Test temperature 21 ° C.

The proposed polymer nanocomposition will make it possible to obtain film and other materials with a wide spectral range of absorption of medium-wave UV radiation (200-420 nm) and with enhanced protection in the short-wave region of the UV range, which is dangerous for biological objects (200-290 nm). This invention will find application in agriculture (greenhouse films) and the packaging industry (for packaging food, electronic products, etc.).

Claims (1)

A polymer nanocomposite that protects against UV radiation, including a polyolefin or an olefin copolymer, characterized in that nanosized silicon carbide is used as the UV absorber, which is single-phase polycrystalline and consisting of synthetic carborundum (SiC) with a 6H polytype moissanite structure with an average particle size 34 ± 3 nm in an amount of 0.1-1.5 wt. %, and the range of absorption of UV radiation and the amount of integrated transmission are 200-420 nm and 90-100%, respectively.