WO2009008562A1

WO2009008562A1 - Optically active inorganic additive and light transforming film including the additive

Info

Publication number: WO2009008562A1
Application number: PCT/KR2007/003366
Authority: WO
Inventors: Jae Suk Sung; Naum Soshchin; Ko Yeon Choo; Tae Hwan Kim; Sang Hyun Kim
Original assignee: ENVIO Co Ltd
Current assignee: ENVIO Co Ltd
Priority date: 2007-07-11
Filing date: 2007-07-11
Publication date: 2009-01-15
Anticipated expiration: 2010-01-11
Also published as: JP2010533223A

Abstract

A photoconversion film includes at least one photoactive inorganic additive selected from the group consisting of the following compounds: 1) Y 2-p-q-z (TR III) p(TRIV )q (TRv)zO2 S, where p is equal to 0.01 to 0.1, q is equal to 0 to 0.001, z is equal to 0 to 0.0002, Y is yttrium, TRIII is europium, TRIII is praseodymium or samarium, and TR is praseodymium or terbium; and 2) Y 2-x-y(TRI)x(TRII y SiO5, where x is equal to 0.01 to 0.1, y is equal to 0 to 0.005, Y is yttrium, TRI is cerium and TRII is neodymium or thulium. With this film, it is possible to convert the ultraviolet spectrum region to a spectrum region useful to the growth of plants.

Description

OPTICALLY ACTIVE INORGANIC ADDITIVE AND LIGHT TRANSFORMING FILM INCLUDING THE ADDITIVE

Technical Field

[1] The present invention relates to a photoactive inorganic additive and a photo- conversion film containing the same and, more particularly, to a photoactive inorganic additive for converting the ultraviolet spectral region of light to a spectral region useful to plant growth and a photoconversion film containing the same. Background Art

[2] Greenhouses are widely distributed over the northern and southern hemispheres of the earth, the climate of which shows a broad diurnal range during the growth period of crops. In order to reduce the undesirable temperature difference between day and night, a need has existed for a temporary or permanent greenhouse equipped with a device for keeping the temperature and light favorable to plant growth. A greenhouse is built by using a sheet or roll made of an inorganic material (e.g., silicate glass) or an organic material (e.g., organic glass and polymer) exhibiting increased transmittance to the light falling within a spectral region of visible ray.

[3] It was first proved by K. A. Timiryazev et al., Russian scientists, that the light of a spectral region capable of reaching plants greatly affects the growth speed and harvest amount of the plants cultivated within a greenhouse. They found that the orange -red light in a wavelength band of 590 to 700nm or the blue light in a wavelength band of 420 to 470nm sharply increases the harvest amount of the plants. Photosynthesis properties of a plant have something to do with optical factors of chlorophyll as a plant green pigment. The theory suggested by K. A. Timiryazev et al. has long been drawing great attention in the field of fundamental and applied study of agriculture.

[4] A new technical field "plant illumination" that governs the light intensity, the light irradiation time and the spectral properties in a greenhouse has been created based on the theory suggested by K. A. Timiryazev et al. In this new technical field, a special glow- lamp and light-emitting-lamp system is installed within a greenhouse and used in accelerating the growth of plants. Thanks to the achievement of research in this field, it became possible to harvest various plants, such as garden plants, vegetables, strawberries, flowering plants and cabbages, in a large quantity over autumn, winter and spring. However, due to the sharp increase in the cost of electricity used in illuminating the greenhouse, the plant cultivation cost has also been increased to a great extent. In view of this, a polymer film for greenhouses has been used in an effort to accelerate the growth of plants over autumn, winter and spring. The polymer film is required to exhibit the following properties.

[5] More specifically, the polymer film needs to have the mechanical strength great enough to withstand a strong wind pressure without being tore up, the light transmittance high enough to transmit the light falling within the whole visible light spectrum region, the absorbability and re-emitting property of infrared rays of 10 to 25

in wavelength emitted from the soil within a greenhouse, and the absorbability of ultraviolet rays of short or middle wavelength contained in the sun light (which property is needed to prevent sunburn damage to the plants possibly caused by ultraviolet rays that tend to increase in recent years due to destruction of the ozone layer).

[6] Russian Patent No. RU2131661 discloses a photoconversion cover for greenhouses formed of a polymer film and an organic glass. However, this photoconversion cover has no great effect on the photosynthesis factors of plants cultivated within a greenhouse.

[7] U.S. S. R. Patent No. SU1780309 discloses a photoconversion film for greenhouses that contains the complex of 1,10-phenantrolyne, 2,2'-dipyridine, 4,4'-dimethyl-2,2'-dipyridine or paraffin europium nitrate.

[8] Russian Patent No. RU2127511 discloses a photoconversion film for greenhouses composed of a thermoplastic polymer, a light stabilizer and europium compound-based inorganic phosphor. Phenozan-23 is used as the light stabilizer. As the inorganic phosphor, use is made of: 1) europium-activated strontium sulfide; 2) calcium sulfide activated by europium, dysprosium and/or terbium; and 3) strontium calcium sulfide activated by europium, dysprosium and/or terbium. The photoconversion film absorbs ultraviolet rays in the light spectrum region of 290 to 330nm or 400 to 440nm and emits red spectrum rays of 580 to 760nm having a peak intensity at 618 to 680nm. The photoconversion film also exhibits a fluorescence property lasting for two hours at most.

[9] In the meantime, there is known a photoconversion film composed of a light- transmitting thermoplastic polymer and a photoactive additive. The photoconversion film has a general expression of [(La Eu )O] (Lig) , where Lig denotes F , Cl , or Br l-x x m n _{2 2 3} in case of m and n being equal to 1 but Lig stands for S , SiO or PO in case of m and n being equal to 2 and 1, respectively. The photoconversion film includes 0.02 to 5wt% of photoactive additive, the remainder being a light-transmitting thermoplastic polymer. However, the photoconversion film is problematic in the following aspects.

[10] First, the constituent materials of the film emit secondary light only in the orange-red spectrum region and do not emit secondary light in the blue spectrum region. This may adversely affect fabaceous plants and other agricultural plants.

[11] Second, the intensity of secondary light emitted becomes high only when the content of the additive in an inorganic oxysulfide-based polymer composition is as high as 0.2 to 0.5 wt%.

[12] The photocon version film shows reduced light-emitting intensity in the red spectrum region and therefore has little influence on the growth of plants. This is due to the lack of film production technology, the failure to optimally control the concentration of the additive, i.e., europium yttrium oxysulfide, and the failure to optimize the emission amount of orange-red spectrum light. Another cause is the reduced efficiency of an optical factor in the photosynthesis. The emission spectrum of europium yttrium oxysulfide is composed of different wavelength peaks of 585nm, 616nm and 626nm. The interval between the wavelength peaks equivalent to about 40nm does not assist in increasing the photosynthesis efficiency. Disclosure of Invention Technical Problem

[13] In view of the above- noted and other problems inherent in the prior art, it is an object of the present invention to provide a photoactive inorganic additive capable of converting the ultraviolet spectral region of light to a spectral region useful to plant growth, and a photoconversion film containing the same. Technical Solution

[14] In one aspect of the present invention, there is provided a photoactive inorganic additive for photoconversion films comprising at least one member selected from the group consisting of the following compounds:

[15] 1) Y (TR ) (TR ) (TR ) O S, where p is equal to 0.01 to 0.1, q is equal to 0 to

2-p-q-z III p IV q V Z 2

0.001, z is equal to 0 to 0.0002, Y is yttrium, TR is europium, TR is praseodymium or samarium, and TR is praseodymium or terbium; and [16] 2) Y (TR ) (TR ) SiO , where x is equal to 0.01 to 0.1 , y is equal to 0 to 0.005, Y

2-x-y I x H y 5 is yttrium, TR is cerium and TR is neodymium or thulium. [17] In another aspect of the present invention, there is provided a photoconversion film comprising at least one photoactive inorganic additive selected from the group consisting of the following compounds: [18] 1) Y (TR ) (TR ) (TR ) O S, where p is equal to 0.01 to 0.1, q is equal to 0 to

2-p-q-z III p IV q V Z 2

0.001, z is equal to 0 to 0.0002, Y is yttrium, TR is europium, TR is praseodymium or samarium, and TR is praseodymium or terbium; and [19] 2) Y (TR ) (TR ) SiO , where x is equal to 0.01 to 0.1, y is equal to 0 to 0.005, Y

2-x-y I x H y 5 is yttrium, TR is cerium and TR is neodymium or thulium.

[20] It is preferred that the photoconversion film further comprises a light stabilizer.

Best Mode for Carrying Out the Invention

[21] The present invention will now be described in detail. The present invention provides a photoactive inorganic additive for use in improving the photocon version property of a photoconversion film. Furthermore, the present invention provides a photoconversion film containing the photoactive inorganic additive. [22] The photoactive inorganic additive in accordance with the present invention includes at least one member selected from the group consisting of the following compounds: [23] 1) Y (TR ) (TR ) (TR ) O S, where p is equal to 0.01 to 0.1, q is equal to 0 to

2-p-q-z III p IV q V Z 2

0.001, z is equal to 0 to 0.0002, Y is yttrium, TR is europium, TR is praseodymium or samarium, and TR is praseodymium or terbium; and

V

[24] 2) Y (TR ) (TR ) SiO , where x is equal to 0.01 to 0.1 , y is equal to 0 to 0.005, Y

2-x-y I x H y 5 is yttrium, TR is cerium and TR is neodymium or thulium.

I II

[25] The inorganic additive represented by the compound 1) is superior in its property of absorbing the ultraviolet region light and converting the same to the red region light useful to the growth of general plants. It is preferred that the compound 1) is added to the photoconversion film in an amount of 0.0001 to 0.02wt% based on the weight of the photoconversion film.

[26] The inorganic additive represented by the compound 2) is superior in its property of absorbing the ultraviolet region light and converting the same to the blue region light useful to the growth of fabaceous plants and other agricultural plants. It is preferred that the compound 2) is added to the photoconversion film in an amount of 0.0001 to 0.005 wt% based on the weight of the photoconversion film.

[27] The compounds 1) and 2) may be added, either independently or in combination, to a polymer material of which the photoconversion film is made. It is preferred that the compounds 1) and 2) are all added to the polymer material. In this case, the ratio of the compounds 1) and 2) is preferably in the range of from 1:1 to 3: 1.

[28] In the present photoconversion film, a light stabilizer may be added in order to increase the light stability of the photoconversion film. One representative example of the light stabilizer is tertiary amino succinate. In case of adding the light stabilizer, the ratio of the light stabilizer and the inorganic additive is preferably 1:1 to 1:3 and more preferably 1: 1.2 to 1:1.5.

[29] A thermoplastic polymer is used in producing the present photoconversion film. The thermoplastic polymer is not particularly limited but may include, e.g., polyethylene, polyvinylchloride, ethylene vinyl acetate and polycarbonate glass.

[30] The present photoconversion film was subjected to a ultraviolet light transmission test, as a result of which it was confirmed that the film does not transmit the ultraviolet light. It was also confirmed that, in case of adding the compounds 1) and T) as the inorganic additive, the film emits blue-orange-red light regardless of whether the light irradiated is artificial ultraviolet light or natural ultraviolet light. The intensity of photon energy in the blue, orange and red spectrum regions depends on the content of the inorganic additive, i.e., the compounds 1) and 2) and the weight ratio of the inorganic additive to the film. However, the light radiation intensity is not changed linearly depending on the quantity of additive. Likewise, the light radiation intensity in the blue, orange and red spectrum regions is changed in a non-linear fashion. In other words, the photoconversion does not occur in proportion to the quantity of additive, which means that the photoconversion amount is increased non-linearly. That is to say, even when the content of the compound 2) as the inorganic additive is increased to a level 50% greater than the afore-mentioned amount (i.e., 0.0001 to 0.005 wt% based on the weight of the photoconversion film), the blue light with a wavelength of 425nm shows only a 20% increase in its intensity.

[31] In the Examples to be described below, the dependency of the additive content on the emission intensity of blue or red spectrum region light was measured. Then, a variety of plant cultivation tests was conducted.

[32] Hereinbelow, the present invention will be described through a number of Examples.

It should be understood that the Examples are presented merely for the sake of easier understanding of the present invention, with no intention to limit the scope of the invention thereto.

[33] Example 1

[34] Y Ce SiO was prepared as blue phosphor and Y Eu O S was prepared as red

1 95 0 05 5 ^{r r r r} 1 95 005 2 ^{r r} phosphor.

[35] 0.5kg of blue phosphor and 2.0kg of red phosphor were used to produce a film having a weight of 1000kg. The blue phosphor and the red phosphor were put into a rotary mixer together with 0.5kg of IRGANOX 1010 (a product of Ciba-Geigy AG, Switzerland) as a thermal stabilizer and an anti-oxidizer and 3kg of TINUVIN 622 (a product of Ciba-Geigy AG, Switzerland) as a hindered amine light stabilizer. The rotary mixer used at this time was preliminarily filled with 20kg of low-density polyethylene and pre-heated to a temperature of 100⁰C. Thereafter, the ingredients in the rotary mixer were mixed for one hour. The mixture thus obtained was transferred to a horizontal extruder in which the temperature of an output plate is maintained at 15O⁰C.

[36] When fully melted, the mixture was extruded into an elongated rod, which was cooled with cooling water and cut into a plurality of granules each having a diameter of 4 to 8mm.

[37] The plurality of granules is called a master batch and has a luminance to the ultraviolet light greater than that of a standard specimen. Assuming that the luminance L of the standard specimen is 100%, the luminance of the master batch is as high as 120%. This means that the ultraviolet light is removed and the radiation intensity in the blue-orange-red spectrum region is increased. [38] A two-layer film with inner and outer layers was produced using a twin head extruder. 35% of the total master batch was used in forming the inner layer of the film, while 65% of the total master batch was used in forming the outer layer. Low-density polyethylene was used a predominant material of the film. The film thus produced is 120

in thickness and 10m in width. The light transmittance of the film is about 91% and the tensile strength thereof is approximately 130kgf/cm . [39] Example 2

[40] 0.25g of Y Ce SiO as blue phosphor and 0.25g of Ba MgEu Al O (BMA) as

1 95 005 5 09 0 1 10 17 standard blue phosphor were used in combination. As in Example 1, 1.5kg of Y Eu O S was used as red phosphor. Also used are lkg of IRGANOX 1010 (a product of Ciba-Geigy AG, Switzerland) as a thermal stabilizer and an anti-oxidizer and 3kg of TINUVIN 622 (a product of Ciba-Geigy AG, Switzerland) as a hindered amine light stabilizer. 20kg of the 4:1 mixture of low-density polyethylene and ethylene vinyl acetate was used in place of the low-density polyethylene employed in Example 1. The mixing operation for the production of a master batch is carried out in the same manner as in Example 1 , except that the output plate of the horizontal extruder is maintained at a temperature of 16O⁰C. The mixture was extruded into an elongated rod, which was cooled with cooling water and cut into a plurality of granules each having a diameter of 4 to 8mm. [41] A three-layer film of 160 to 180

in thickness with inner, middle and outer layers was produced. 15% of the total master batch was used in forming the inner layer of the film, with 35% and 50% thereof used for formation of the middle and outer layers. Low-density polyethylene was used a predominant material of the film.

[42] In order to avoid the inner layer becoming hazy, namely to avoid the formation of dewdrops, fluorinated low-density polyethylene was added as an anti-dewdrop agent.

[43] The three-layer film thus produced is as high in tensile strength as about 200kgf/cm , which is sufficient to endure the snow slip and the strong wind in winter.

[44] Plant Cultivation Test

[45] Plant cultivation tests were performed in the same method as used in a conventional greenhouse test for measuring the reduction rate of carbon dioxide generated by carbon dioxide assimilation of plants within a greenhouse. The test results revealed that, as compared to a greenhouse built with a pure polyethylene film, the greenhouse constructed from the present film increases the growth rate of plants (one week in case of tomatoes and hot peppers, although there is a difference depending on the kinds of plants) and shortens the time within which plants come into full maturity (one week in case of tomatoes).

[46] The embodiment set forth hereinabove has been presented for illustrative purpose only and, therefore, the present invention is not limited to this embodiment. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention defined in the claims. Industrial Applicability

[47] With the present invention, it is possible to efficiently convert the ultraviolet spectrum region to a spectrum region useful to the growth of plants. Despite the reduction in thickness, the present photocon version film containing a photoactive inorganic additive has a short wavelength light absorbance equivalent to that of an inorganic glass sheet. The photon yield rate of the present film at the time of re- emission is as high as 0.75 to 0.9. The brightness of an emission spectrum exceeds the brightness of a light spectrum having the same wavelength, thereby exhibiting the Timiryazev spectrum effect. In addition, the present photoconversion film serves to scatter or reflect infrared light of long wavelength, which helps increase the temperature of soil within a greenhouse.

Claims

[1] A photoactive inorganic additive for photocon version films comprising at least one member selected from the group consisting of the following compounds:

1) Y 2-p-q-z (TR III ) p (TR IV ) q (TR V )z O 2 S, where p is equal to 0.01 to 0.1,' q ~L is eq ~Lual to 0 to 0.001, z is equal to 0 to 0.0002, Y is yttrium, TR is europium, TR is praseodymium or samarium, and TR is praseodymium or terbium; and

2) Y 2-x-y (TR I )x (TR H )y SiO 5 , where x is eq ⁿual to 0.01 to 0.1,> y J is eq 1ual to 0 to 0.005,

Y is yttrium, TR is cerium and TR is neodymium or thulium.

[2] A photoconversion film comprising at least one photoactive inorganic additive selected from the group consisting of the following compounds:

1) Y (TR ) (TR ) (TR ) O S, where p is equal to 0.01 to 0.1, q is equal to 0

2-p-q-z III p IV q V z 2 to 0.001, z is equal to 0 to 0.0002, Y is yttrium, TR is europium, TR is praseodymium or samarium, and TR is praseodymium or terbium; and

2) Y (TR ) (TR ) SiO , where x is equal to 0.01 to 0.1, y is equal to 0 to 0.005,

2-x-y I x H y 5

Y is yttrium, TR is cerium and TR is neodymium or thulium.

[3] The photoconversion film as recited in claim 2, further comprising a hindered amine light stabilizer. [4] The photoconversion film as recited in claim 2, wherein the compound 1) has a content of 0.0001 to 0.02wt% based on the weight of the film. [5] The photoconversion film as recited in claim 2, wherein the compound 2) has a content of 0.0001 to 0.005 wt% based on the weight of the film. [6] The photoconversion film as recited in claim 2, wherein the composition ratio of the compounds 1) and 2) is 1:1 to 3: 1.