RU2229496C2 - Polymer composition for manufacturing film envelops - Google Patents

Abstract

FIELD: polymer materials. SUBSTANCE: polymer composition than can be used for manufacturing envelops for greenhouses contains 0.02-0,5% europium-activated yttrium oxysulfide, 0.04-4.5% IR corrector, 0.1-1.0% thermo-and-photo stabilizer, and thermoplastic material - the rest. IR corrector is a light correcting additive, which absorbs and transforms infrared constituent of sun emission into visible emission and/or into infrared emission with different wavelength. IR corrector can be selected from compounds of the type M-Ln, where M denotes yttrium (lanthanum) oxysulfide, yttrium (lanthanum) (oxy)halide, or barium (calcium) (oxy)halide; and Ln denotes erbium or ytterbium; and also compounds of the type M-Er, where M denotes calcium tungstenate or yttrium oxysulfide and Er erbium. Particles of indicated composition components are below 20 mcm in size. Above-mentioned thermoplastic material is polyethylene and thermo-and-photo stabilizers are tivunin 622 and tivunin 783. EFFECT: increased portion of light energy in spectrum region stimulating photosynthesis in plants, and enabled protection of plants against overheating during hot time. 3 cl, 1 dwg, 4 tbl, 9 ex

Description

The invention relates to polymer compositions, namely, compositions for producing absorbing and / or reflecting light radiation and luminescent materials, and can be used in the manufacture of light-distributing materials, for example, light-correcting coatings of greenhouses and greenhouses.

It is known that the introduction into the polymer composition (matrix) of luminescent additives, in particular derivatives of rare-earth elements, can significantly increase the efficiency of the use of light incident on plants by converting the ultraviolet (UV) component of the spectrum into radiation with a wavelength that promotes the photosynthesis process.

Known polymer composition based on (co) ethylene polymer for the production of selectively absorbing light and luminescent films that convert the UV component of the solar or other light sources into red spectrum radiation, which can be used in various fields, for example, in agriculture (1. Pat. RU 2132346, C 08 L 23/04, C 08 K 3/10, C 08 K 5/09. Polymer composition for producing films. Anisimov VM and other publ. 06/27/1999). The polymer composition includes an active additive, which is used as a three-component mixture ABC, where A is the oxide, organic or inorganic salt of europium; B is a compound from the class of β-diketones; C is a compound from the class of bidentate nitrogen heterocycles or from the series of trialkyl (phenyl) substituted phosphine oxides, in the following ratio (wt.%): Active additive 0.05-1.0; (co) ethylene polymer - the rest.

A disadvantage of the known solution is the low photostability of the light-correcting additives and the resulting polymer film.

A known composition of a film of polymeric material for coating greenhouses and an optical activator for polymeric material (2. Pat. RU 2127511, IPC ⁶ A 01 G 9/22; Morozov EG and other publ. 20.03.1999). The known coating for greenhouses contains a thermoplastic polymer, a stabilizer and an optical activator based on europium compounds. As an activator, strontium sulfide activated by europium, or strontium and calcium sulfides activated by europium, or strontium sulfide activated by europium, dysprosium and / or terbium, or strontium sulfide activated by europium, dysprosium and / or terbium, are used. As a stabilizer, the composition contains phenosan-23. The film material obtained using the proposed optical activators has light-converting properties: it absorbs ultraviolet radiation from the solar spectrum in the range of 250-330 and 400-440 nm and emits in the red region of the spectrum in the range of 580-760 nm, with a maximum of 618-680 nm

The disadvantage of this solution is the low stability of the light corrector during operation under environmental conditions (moisture, sunlight).

The closest analogue of the claimed technical solution for chemical composition and functional purpose is "Protective polymer film for coating greenhouses and greenhouses and the method of its production" (3. Pat. US No. 6153665, Int. Cl. ⁷ C 08 K 3/00, Goldburt etc Published on 11/28/2000. Selected for the prototype). From the description of the patent it is known that a polymer film is obtained from a composition based on a thermoplastic material (high-pressure polyethylene - up to 98.5 wt.%). The composition contains additives: yttrium oxysulfide activated by europium, with a grain size of 4 to 20 μm (light-converting additive) in an amount of 0.05-0.5 wt.% And light stabilizer (polyaminosuccinate) in an amount of 0.1-1.0 weight. % with a preferred ratio of these components to each other 1: 2. The film has light-correcting properties: UV radiation is converted into a light wave, which stimulates the photosynthesis process in plants. The use of the film allows you to extend the growing season, increase productivity and the quality of the grown products, makes it possible for roses to bloom 30 days earlier than usual. According to the authors, due to the combined action of the light converting additive and the used light stabilizer, a synergistic effect is observed - an increase in the strength of the material, and the film's service life is at least two years.

Despite certain advantages, the well-known polymer film has low efficiency due to the insufficiently complete conversion of the light energy (electromagnetic radiation) of the Sun. The magnitude of the flux of solar radiation incident on the Earth is about 1 kW / m ² in the wavelength range of 0.3-2.5 microns; an approximate distribution of its intensity over the spectrum: ultraviolet (UV) - 9%, visible - 45%, infrared (IR) - 46%. According to the prototype, only the UV component of the spectrum is converted into visible radiation, i.e. only about 9%. The conversion is carried out by the Stokes luminescence method. The near-infrared region, which accounts for about 46% of all energy received, is not used, which reduces the efficiency of light correction. Another disadvantage of the prototype is the possibility of overheating (burns) of plants when the temperature rises in the greenhouse, especially during the hot season and in areas with a hot climate.

The objective of the invention is to increase the efficiency of light correction of solar radiation by involving in the redistribution of the near infrared spectrum in the wavelength range from 0.8 to 1.6 μm, which constitutes a significant fraction (more than 40%) of the integral intensity of electromagnetic radiation of the Sun in the region of the Earth. To do this, you must:

- to increase the share of light energy received by plants in the spectral region, stimulating the photosynthesis process in plants, due to the transformation of near-infrared radiation into this photoregulatory region;

- in the hot season (day) to protect plants from radiation in the near infrared range and protect plants under a protective film from overheating, i.e. use the so-called "optical cooling effect" [4. Physical Encyclopedia. - M .: Owls. Encyclopedia, vol. 1, p. 108].

The problem is solved by converting the film coating not only UV radiation, but also radiation in the near infrared range (in the range from 0.8 to 1.6 μm), namely due to luminescence, the wavelength of which can be either less or more wavelengths of exciting radiation. The effect is achieved by the fact that the polymer composition for the manufacture of a film coating based on a thermoplastic material additionally contains a light-correcting additive (IR corrector) that absorbs and converts the infrared component of solar radiation into the radiation of the visible region of the spectrum and / or into infrared radiation with a different wavelength, granulometric particle sizes less than 20 microns, with the following ratio of components (wt.%):

Yttrium Oxisulfide Activated by Europium 0.02-0.5

The above IR corrector 0.04-4.5

Thermal light stabilizer 0.1-1.0

Thermoplastic material

Thus, in the claimed technical solution, the phenomena of both Stokes and anti-Stokes luminescence are used. Technical solutions using this combination of features have not been used to date.

As an IR corrector, (oxy) halides, yttrium, lanthanum, lanthanum, alkaline-earth metal oxidesulfides with a particle size distribution of 1 to 20 μm, activated by erbium and / or ytterbium (sensitizer) and erbium (activator) are used. Instead of erbium, holmium or thallium can be used as an activator, however, erbium is preferable as a relatively cheaper material.

As the mentioned IR corrector, compounds of the M-Ln type can be used, where M is yttrium (lanthanum) oxysulfide and / or (oxy) yttrium (lanthanum) halide or (oxy) barium (calcium) halide, Ln is erbium and ytterbium, as well as compounds of the M-Er type, where M is calcium tungstate or yttrium oxysulfide; Er is erbium. These substances are added to the composition in an amount of 0.04-4.5 wt.%.

These specific additives are most effective, because are resistant to operation under conditions of exposure to moisture and electromagnetic radiation of the Sun and are most effective with respect to the conversion of infrared radiation to the red region of the spectrum (see Table 2).

The mechanism of "optical cooling" proceeds as follows.

Different photocorrection additives with different chemical compositions have different regions of maximum conversion efficiency in the range of absorption and excitation of luminescence. Typically, this range is from 0.8 to 1.6 microns. The sensitivity of the additives (threshold energy of the luminescent conversion) in the field of maximum excitation is 10 ^-2 -10 ^-3 W / cm ² . At the edges of the excitation region, i.e. in the wavelength ranges of 0.8-0.9 microns and 1.2-1.6 microns, the sensitivity decreases to 1-10 W / cm ² . Moreover, in the case of the introduction of the same sensitizer, for example ytterbium, the IR excitation spectra of the visible glow of various activators (erbium, holmium, thulium) are almost identical to each other and have a well-defined maximum (5. Chukova Yu.P. Anti-Stokes luminescence and new the possibilities of its application. M.: Sov. radio, 1980). Mentioned in the statement of the problem, the protection of plants from overheating is achieved by choosing additives with a relatively low threshold of luminescent conversion energy, which ensures “self-inclusion” of protection when the incident radiation parameters reach a critical value. When the energy of the infrared radiation incident on the material increases, the IR corrector begins to reemit it by two mechanisms: the Stokes, that is, toward the longer wavelength, and the plant receives radiation with lower energy, and the anti-Stokes, towards the smaller wavelength, i.e. into visible light, different in spectral composition (Tables 1, 2). Table 1 shows some of the compositions of the IR corrector, of which compositions containing, along with the europium activated yttrium oxysulfide, the following additives are of particular practical importance:

- yttrium oxysulfide activated by erbium and ytterbium;

- lanthanum oxysulfide activated by erbium and ytterbium;

(hydroxy) yttrium halide (e.g. oxychloride or oxyfluoride) activated by erbium and ytterbium;

- yttrium barium halide BaYF ₅ activated by erbium and ytterbium;

- calcium tungstate activated by erbium;

- yttrium oxysulfide activated by erbium.

Table 2 shows the quantum efficiency of anti-Stokes luminescence of a pair of Er, Yb ions in various ranges of the visible region of the light (wavelength of the exciting light 0.987 ± 0.06 μm; IR radiation intensity 1 W / cm ² ; T = 295 K). From the data given in Table 2, it is seen that to obtain the red component of light, it is better to use yttrium oxyhalides. Yttrium (lanthanum) oxysulfide should be used both to obtain the red component and to achieve the effect of optical cooling, since the IR corrector re-emits in the red and green spectral regions, and its quantum efficiency increases with increasing flow rate. In addition, these materials are well compatible with polyethylene and are most resistant to the combined effects of moisture and radiation, i.e. in conditions characteristic of the film coating of greenhouses and greenhouses.

As stabilizers in the claimed composition, spatially hindered amine light stabilizers, for example, a diethyl succinate derivative, tinuvin 622, or a mixture thereof with chemical massorb 944 in a 1: 1 ratio (tinuvin 783) were used. They, as a rule, are also good thermal stabilizers. Additionally, phenolic type thermal stabilizers can be introduced: irganox 1010 and / or irganox 1076. In order to increase the ability of water to drain from the film, substances from the number of glycerol stearates or other known antifobic additives can be added to the composition. This reduces droplet formation and, accordingly, the drop of water droplets from the film onto the plants. Such technical solutions are well known and are not given in the claims.

The claimed invention is implemented in experiments and tested in practice.

General part: polyethylene of the PEVD 15803-020 grades (premium and first grade) and HDPE 15813-020 (premium and first grade) were used as thermoplastic material; a film based on the latter was characterized by higher transparency and strength. A film (sleeve) with a thickness of 100, 150, and 200 μm was obtained by blowing using a laboratory extruder and an industrial plant such as ORP, additives of UV and IR correctors, thermal stabilizers, etc. were introduced by dusting granules of polyethylene before loading with liquid paraffin or transformer oil, as well as by preliminary the manufacture of the concentrate of these additives with polyethylene by analogy with the methodology of the prototype. There were no differences in the properties of the film obtained using these two methods of adding a corrector. The transmission spectra (and the associated absorption, reflection spectra) and luminescence spectra were recorded on a Spekord M40 instrument, on a KSVU-23 spectral computing complex and on a setup for measuring diffuse reflectance and luminescence spectra (6. Mikhailov MM. Optical degradation prediction temperature-controlled coatings of spacecraft. Novosibirsk: Science. Sib. publishing company, p. 15-16). A sample of the obtained graphs is shown in the drawing.

When excited by IR radiation with a wavelength of 0.96 μm (IR LED with a power of 1 W / cm ² ), the conversion efficiency of IR radiation to visible for compositions with yttrium oxysulfide, lanthanum oxysulfide (green and red) is 0.2%, and with oxyhalide yttrium (red region) - about 1%. Weak visible luminescence was observed when the IR corrector was not less than 0.04 wt.%, When the composition was excited in the UV spectral region of the composition with yttrium oxysulfide activated by europium, weak red luminescence visible to the eye was observed with a minimum UV corrector of 0.02 wt.% that determines the boundaries of the claimed quantitative range.

The invention is illustrated by examples.

Example 1. A mixture containing LDPE (99.38 kg), tinuvin 622 (0.2 kg) and yttrium oxysulfide activated by europium (0.02 kg), calcium tungstate activated by erbium (0.4 kg) with grain size in the range of 15-20 microns was obtained by dusting with liquid paraffin with thorough mixing. The resulting composition was loaded into the feed hopper of the film stretching apparatus; a film (sleeve) 1.5 m wide and 100 μm thick was obtained at a melt temperature of 190 ° C. The conversion efficiency of IR radiation (1.48-1.55 μm with the simultaneous action of 0.71-0.85 μm) in the green region of the spectrum (0.54-0.56) is about 0.1%, and infrared (0, 71-0.85 microns) in infrared (1.5 microns) - about 0.4%. The conversion of UV radiation to the red region of the spectrum (with a minimum content of UV corrector of 0.02%) is 30% lower compared to the prototype, but the radiation is still visually detected in a dark room. The mechanical strength of the resulting film is unchanged.

Example 2. A mixture containing LDPE (3.31 kg), chemical massorb 944 (6.7 g) and yttrium oxysulfide activated by europium (6.7 g), yttrium oxysulfide activated by ytterbium and erbium (13.3 g), s grain sizes in the range of 10-15 microns were obtained by dusting with liquid paraffin with thorough mixing. The resulting composition was loaded into a loading funnel of a laboratory setup for drawing a film; a film (sleeve) with a width of 0.2 m and a thickness of 100 μm was obtained at a melt temperature of 180 ° C. Mechanical strength unchanged. The conversion efficiency (spectral parameters) corresponds to the data given in example 1 and table 2.

Example 3. A film (sleeve) with a width of 1.5 mi and a thickness of 150 μm was obtained in an apparatus for drawing a film at a melt temperature of 190 ° C using a previously obtained concentrate. Composition: UV corrector (yttrium oxysulfide activated by europium 0.05 wt.%) + IR corrector (yttrium oxysulfide activated by erbium and ytterbium 0.03%, yttrium oxychloride activated by erbium and ytterbium 0.02%) + tinuvin 783 0.2% + LDPE 15813-020 the rest. The efficiency of IR conversion in accordance with the data in table 2; the radiation intensity in the red region of the spectrum increased by 10%. Mechanical strength unchanged.

Example 4. Similar to example 3, but was added antifobic additive Atmer 103 in an amount of 2% by weight. Mechanical strength and photostability (service life) of the film without visible changes.

Example 5. Similar to example 3, but glycerin stearate was added in an amount of 1 wt.%. Mechanical strength and photo resistance without visible changes.

Testing of samples of a polyethylene film with various additives for mechanical strength was carried out in the longitudinal and transverse directions as follows.

Stripes of 3 × 20 cm in length were cut in the longitudinal and transverse directions, a central section 10 cm long was selected, the sample was fixed between two holders and stretched until it broke, the length of the central section was measured after stretching, n is the number of measurements for each sample. The results are summarized in table 3.

Samples No. 5, 6, 9 were investigated for photostability (change in mechanical strength and luminescence). The samples were placed at a distance of 0.35 m from the PRK-200 radiation source (UV and visible light) and were irradiated at 50 ° С for various times (from 60 to 1380 min). The mechanical strength of the studied samples after their irradiation in the indicated time interval did not deteriorate; the luminescence spectrum (intensity) did not change significantly. Therefore, samples No. 5, 6, 9 cut in the transverse direction were irradiated for 210 minutes using a more intense DRL-400 radiation source (the distance from the source to the samples was 0.2 m). As can be seen from the results of table. 3 and 4, indicators of luminescence and mechanical strength of the claimed coating without visible changes, in contrast to the composition of the prototype. According to the results of industrial tests conducted in greenhouse constructions from February 1999 to the present (July 2001), the photostability and mechanical strength of compounds with an oxysulfide IR corrector allows it to be used as year-round greenhouse coatings for at least 2.5 years (an act is attached ) According to the results of laboratory tests, this period is at least 4 years.

References

1. Pat. RU 2132346; IPC ⁶ C 08 L 23/04, C 08 K 3/10, C 08 K 5/09. A polymer composition for producing films. Anisimov V.M. and other publ. 06/27/1999.

2. Pat. RU 2127511; IPC ⁶ A 01 G 9/22; Morozov E.G. and other publ. 03/20/1999.

3. Pat. US No. 6153665, Int. C1. ⁷ C 08 K 3/00, Goldburt etc. Publ. 11/28/2000. Prototype.

4. Physical encyclopedia. - M .: Owls. Encyclopedia, vol. 1, p. 108.

5. Chukova Yu.P. Anti-Stokes luminescence and new possibilities for its application. M .: Sov. radio, 1980.

6. Mikhailov M.M. Prediction of optical degradation of temperature-controlled coatings of spacecraft. Novosibirsk: Science. Sib. ed. company, pp. 15-16.

Claims (3)

1. A polymer composition for the manufacture of a film coating based on a thermoplastic material containing yttrium oxysulfide activated by europium and a thermal light stabilizer, characterized in that it additionally contains a light-correcting additive (IR corrector), which absorbs and converts the infrared component of solar radiation into visible radiation and / or into infrared radiation with a different wavelength, with particle sizes less than 20 microns, in the following ratio of components entov, wt.%: Yttrium oxysulfide, activated by europium 0.02 - 0.5 The above IR corrector 0.04 - 4.5 Thermal light stabilizer 0.1 - 1.0 Thermoplastic material 2. The polymer composition according to claim 1, characterized in that as the mentioned IR corrector, a compound of the type M-Ln is used, where M is yttrium (lanthanum) oxysulfide and / or (oxy) yttrium (lanthanum) halide or (oxy) halide barium (calcium); Ln - erbium and ytterbium. 3. The polymer composition according to claim 1, characterized in that as the mentioned IR corrector, a compound of the type M-Er is used, where M is calcium tungstate or yttrium oxysulfide; Er is erbium.