JPH0318182Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a weather-resistant laminated polyester film used for agricultural and horticultural greenhouses and the like. Specifically, the present invention relates to a laminated polyester film that, when used as a base material for growing a greenhouse, has good UV transmittance at wavelengths required for the cultivation of flowers, fruits, etc., and can withstand long-term outdoor exposure. [Prior Art] Conventionally, polyester films have had poor weather resistance. However, by taking advantage of the excellent mechanical and optical properties of polyester film,
Polyester films that have been given weather resistance so that they can be used as outdoor base materials for agricultural greenhouses, etc., include: (1) UV absorbers and light stabilizers are kneaded into the film to give it weather resistance. Weather-resistant polyester film (Japanese Patent Publication No. 57-6470) (2) Weather-resistant polyester film that has been given weather resistance by coating the film surface with an organic polymer binder containing an ultraviolet absorber and a light stabilizer Showa 56
-159239) are known. [Problems to be solved by the invention] However, the above-mentioned weather-resistant polyester film has the following problems. In the film described in item (1) above, deterioration of the film usually progresses from the exposed surface to the inside when exposed outdoors, so in order to improve the weather resistance of the surface, it is necessary to increase the concentration of added ultraviolet absorbers, etc. throughout the film. However, as the concentration increases, the ultraviolet cut range of the film expands, so when used for greenhouse purposes, the lack of ultraviolet rays may cause poor color development of flowers, fruits, etc., or insects such as bees cannot use the film for pollination. In addition, in the film described in item (2) above, the wet tension of the polyester film surface is as low as 38 to 45 dyne/cm, making it difficult to form a strong coating layer, and furthermore, the coating layer may peel off due to long-term outdoor exposure. or cause cracks on the surface. Furthermore, if the combination of the organic polymer binder and the ultraviolet absorber is incorrect, the ultraviolet absorber and the like in the coating layer will recrystallize and become cloudy and opaque. The present invention eliminates the drawbacks of these conventional technologies and, when used as a film for agricultural greenhouses, sufficiently transmits the ultraviolet rays of sunlight necessary for cultivation, and
The purpose of the present invention is to provide a laminated polyester film with excellent transparency and long-term weather resistance. [Means for solving the problem] The present invention is based on polyester with a thickness of 25~25 mm.
At least one side of the 350 μm film (A) is covered with a 11-30 μm thick film (B) mainly made of polyester.
It is a laminated film provided with a chemical structural formula (Here, R represents an ester group or a methyl group.) The organic compound represented by (R represents an ester group or a methyl group) is contained in the film (A) in an amount of less than 0.08% by weight based on the film (A), and in the film (B) in the film (B). Contains 0.08 to 1.2% by weight,
In addition, the laminated film has both films (A) and (B) biaxially stretched, and has an ultraviolet transmittance of 25 to 65% at a wavelength of 350 mμ.
It is characterized by being a laminated polyester film. In the present invention, polyester refers to known polyesters such as terephthalic acid, iriphthalic acid,
At least one bifunctional carboxylic acid such as naphthalene dicarboxylic acid, bis-α,β(2-chlorophenoxy)ethane-4,4′-dicarboxylic acid, adipic acid, and sebacic acid, and ethylene glycol, triethylene glycol, and trimethylene glycol.・
Examples include polyesters obtained by polycondensation with at least one glycol such as tetramethylene glycol, hexamethylene glycol, and decamethylene glycol. Further, the polyester may be copolymerized or blended with other polymers within a range that does not impede the purpose of the present invention, and may contain antioxidants, heat stabilizers, lubricants, etc. The intrinsic viscosity of the polyester (measured in orthochlorophenol at 25° C.) is usually in the range of 0.4 to 2.0, preferably 0.55 to 1.0.
In the present invention, particularly excellent effects can be obtained when polyethylene terephthalate or polyethylene-2,6-naphthalate is used as the polyester. The film (A) in the present invention is a film made of polyester having the composition described above. The film (B) in the present invention is made of polyester having the composition described above, contains the following organic compound, and is laminated on the film (A). Note that the composition of film (B) does not necessarily have to be the same as that of film (A), but if the composition is the same as film (A), the laminated film will not have the risk of deterioration of flatness such as curling. preferable. The organic compound referred to in the present invention is one represented by the above chemical structural formula, and specifically, a dibenzophenone-based ultraviolet absorber [“Mark” LA-51
(manufactured by Adeka Argus Co., Ltd.)] and has extremely excellent ultraviolet absorption ability and heat resistance, and is also extremely compatible with polyester. Film (A) constituting the laminated film of the present invention
is a biaxially oriented film with a thickness of 25~
It needs to be in the range of 350 μm, preferably 50 to 250 μm, and more preferably 75 to 150 μm. If the film thickness is less than 25μm, the mechanical properties such as strength and elongation will be insufficient as a film for agricultural greenhouses.
A thickness of 350 μm or more is not preferable because the light transmittance when formed into a laminated film decreases. Further, the film (B) constituting the laminated film of the present invention is a biaxially oriented film, and has a thickness of 11 to
30μm, preferably 13-28μm, more preferably
It needs to be in the range of 20 to 25 μm. If the film thickness is less than 11 μm, harmful light rays, which are the wavelengths that have the most adverse effect on photodeterioration of polyester films, will pass through, so that sufficient weather resistance cannot be imparted when used as a laminated film. If the thickness is 30 μm or more, harmful rays cannot reach the layer, so making the layer containing an organic compound thicker than necessary is disadvantageous in terms of film manufacturing costs. The concentration of the organic compound added to the film (A) is
It should be less than 0.08% by weight, preferably less than 0.03% by weight. If the amount added exceeds 0.08% by weight, the ultraviolet ray cut range will be expanded when a laminated film is formed, which is not preferable. The concentration of organic compounds added to film (B) is 0.08
The content should be in the range of ~1.2% by weight, preferably 0.1-1.0% by weight, and more preferably 0.4-0.7% by weight. If the additive concentration is less than 0.08% by weight, sufficient weather resistance cannot be imparted to the surface of the laminated film. 1.2
If it is more than % by weight, when used as a laminated film in an agricultural greenhouse, it is not preferable because the amount of ultraviolet rays transmitted necessary for cultivation will be insufficient for crops. The laminated film of the present invention needs to have a transmittance of ultraviolet light having a wavelength of 350 mμ in the range of 25 to 65%, preferably 40 to 64%, and more preferably 50 to 60%. If the transmittance of 350mμ ultraviolet rays is less than 25%,
When used in agricultural greenhouses, the insufficient amount of ultraviolet rays may cause poor color development of cultivated flowers, fruits, etc., and honey bees, etc., cannot be used for pollination when cultivating strawberries and melons. More than 65% of tomatoes under cultivation
This is undesirable because it increases the incidence of diseases such as gray mold and sclerotium on vegetables such as cucumbers. In the film of the present invention, the transmittance of ultraviolet light at a wavelength of less than 350 mμ is not particularly limited, but it is desirable that it is small. Furthermore, the transmittance of ultraviolet light with a wavelength of 350 mμ or more is not particularly limited, but it is preferably 50% or more. Furthermore, it is more preferable that the visible light and infrared transmittance be as high as possible. Next, one embodiment of the present invention will be described based on the drawings. Figures 1 and 2 are cross-sectional views of the laminated film of the present invention, the former showing a two-layer lamination and the latter a three-layer lamination, where 1 is a polyester film (A) and 2 is a polyester film (B). . As shown in the figure, the film of the present invention is a laminated film, but
In addition to the adhesive, other transparent layers may be included between the layers. Further, a drip-proofing agent may be applied to at least one side of the laminated film. Next, a method of manufacturing the film of the present invention will be explained. (1) Coextrusion method: An example in which polyethylene terephthalate (hereinafter abbreviated as PET) is used as the polyester will be explained. PET chips manufactured by conventional methods are used as the main extruder,
0.08~1.2% by weight of the above organic compound on PET chip
The added mixture is fed to the sub-extruder and heated to 260-310℃.
The melts are combined in the same die and then extruded onto a cast drum cooled to 20 to 90°C to form a laminated unstretched film. On this occasion,
The intrinsic viscosity of unstretched film is determined from the film properties.
It is preferably 0.5 or more. Next, the unstretched film is biaxially stretched and oriented. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. The biaxial orientation conditions are not particularly limited, and the stretching temperature is usually 80 to 170°C, preferably 95 to 150°C in both the longitudinal and width directions of the film, and the stretching ratio is 2.0 to 150°C.
5.5 times, preferably 2.5 to 4.5 times. Furthermore, the biaxially oriented film may be heat treated if necessary. Heat treatment conditions are temperature 160~240℃, time 0.5
~120 seconds, preferably 1.0 to 60 seconds is appropriate. (2) Lamination method using adhesive A biaxially oriented film made of PET formed under the conditions of (1) above by a conventional method, and a biaxially oriented film formed by adding the organic compound to PET and formed under the conditions of (1) above by a conventional method. The biaxially oriented film may be continuously bonded with an adhesive made of an organic polymer. At this time, the surface of each film with the adhesive interposed therebetween can be more firmly bonded and laminated by subjecting it to a known corona discharge treatment or plasma treatment (in air, nitrogen, carbon dioxide, etc.). Adhesive coatings are mainly made of well-known thermoplastic resins and thermosetting resins, and also contain organic solvents and
It consists of auxiliary additives, etc. As a method for applying the adhesive, publicly known methods such as a bar coating method, an air knife method, a gravure coating method, and a dipping method can be applied. For the bonding method, a known pressure roll or the like can be used. Further, the thickness of the adhesive, the drying conditions of the adhesive coating, the pressing conditions, etc. are not particularly limited, but it is preferable that the drying and pressing conditions are within a range that does not adversely affect the polyester film. Incidentally, it is most preferable to employ the above-mentioned coextrusion method (1) as the method for producing the film of the present invention. [Evaluation Method] The characteristic values of the present invention are based on the following measurement method and evaluation conditions. (1) Weather resistance test Using a high-pressure mercury lamp (manufactured by Toshiba Electric Corporation, mercury lamp H-400F for fading test), the sample was placed 220 mm from the light source.
Ultraviolet rays placed in a rotating frame surround a distant area. Then, the elongation at break of the film was measured every time the film was irradiated for a predetermined period of time, and the deterioration life (the time when the elongation at break became 2% or less) was determined. Breaking elongation is JIS-C-2318-
72, and the elongation is expressed as a percentage of the original length at break. (2) Light transmittance The spectrum from the ultraviolet region to the visible region (wavelength range of 300 to 700 mμ) was measured using a broadband self-recording spectrophotometer (Hitachi model 323), and the transmittance at a wavelength of 350 mμ was determined. (3) Practical test of bees for pollination After planting strawberry seedlings in a multi-building greenhouse of 300 tsubo,
During the period from late March to early April, when flowering began, one part of the greenhouse (60 tsubo) was partitioned off and a test film was spread on the roof of the greenhouse. A group of bees (approximately 5,000 bees) was then placed inside the greenhouse along with the hive, and a week later, the activity of the bees was observed and the practicality of the test film was tested. The criteria for evaluation were as follows. ○: Good (bees' pollinator activity is active and they have a homing instinct) △: Slightly poor (bees' pollinator activity is somewhat slow) ×: Poor (bees' pollinator activity has stopped) (4) Film-forming properties The volatility of organic compounds during film-forming, bad odor, and amount of lead-out onto the cast drum surface were observed and evaluated. Judgment criteria are: ○: Good, △: Slightly poor, ×;
It was marked as defective. [Effects of the present invention] In the present invention, the polyester film (B) containing a specific amount of a specific organic compound is laminated on at least one side of the polyester film (A), so the characteristics of each film layer are utilized and the following effects are achieved. I was able to get [Effects of the present invention] (1) When used in agricultural greenhouses, it transmits ultraviolet rays at specific wavelengths, so flowers, fruits, etc. can be cultivated with good color development, and even bees can be grown. Can be pollinated by insects such as. (2) When used in agricultural greenhouses, the high transparency allows a large amount of light to pass through the greenhouse, promoting the growth of crops. (3) When used in an agricultural greenhouse, it has long-term weather resistance, so the greenhouse can be used for a long time. The laminated polyester film of the present invention can be used as a spreading material for agricultural and horticultural greenhouses, especially for floriculture.
It is more preferable to use it for melon/strawberry cultivation houses. In addition, it can be used as a stretching material for fish farming houses, hot water pool houses, etc., and can also be used as an outdoor stretching material for road signs, blinds, etc. by laminating it with other films. [Example] Next, embodiments of the present invention will be described based on Examples. Example 1, Comparative Examples 1 to 3 PET homopolymer chips (intrinsic viscosity 0.62, melting point 259°C) manufactured by a conventional method were supplied to the main extruder, and the PET chips were given the chemical structural formula; A dry blend of 0.5% by weight of the organic compound represented by is supplied to a sub-extruder, each melt-extruded at 280°C, each melt is combined in a T-shaped nozzle, and the surface temperature is adjusted to 20°C using an electrostatic application method. The film was wound around a cooling drum and cooled and solidified to obtain a two-layer laminated unstretched film. Next, the film was stretched 3.2 times in the longitudinal direction by a roll method at 90°C, then 3.5 times in the width direction by a tenter method, and heat treated at 210°C for 10 seconds to form a biaxially oriented laminated PET film. I got it.
In addition, during the film forming process, there was almost no decrease in film IV (intrinsic viscosity) or volatilization due to thermal decomposition or sublimation of organic compounds. The thickness of the thus obtained laminated film was 125 μm, and the thickness of the organic compound-containing layer was 18 μm. As shown in Table 1, this laminated film had a UV transmittance of 52% at a wavelength of 350 mμ and good weather resistance. When this laminated film was spread on an agricultural greenhouse with the organic compound content on its outer surface, there was no problem with the activity of bees during the pollination season, and the film had good weather resistance. However, when the organic compound is outside the scope of the present invention (Table 1, Comparative Examples 1 to 3),
Since the amount of volatilization during the film forming process was large and the weather resistance was insufficient, it could not be used as a film for greenhouses. Examples 2 to 4, Comparative Examples 4 and 5 Using the same raw materials and the same method as in Example 1, films were made with slightly different film forming conditions and different organic compound concentrations and laminated thicknesses in the laminated film. As can be seen from Table 1, when the physical properties of the film were within the range of the present invention (Examples 2 to 4), films for greenhouses with excellent ultraviolet transmittance and weather resistance were obtained. However, in cases where the physical properties of the film were outside the scope of the present invention (Comparative Examples 4 and 5), films excellent in both ultraviolet transmittance and weather resistance could not be obtained. 【table】

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of the laminated film of the present invention. 1: Base polyester film, 2: Laminated polyester film.

Claims (1)

[Claims for Utility Model Registration] A laminated film in which a film (B) mainly composed of polyester and having a thickness of 11 to 30 μm is provided on at least one side of a film (A) having a thickness of 25 to 350 μm mainly composed of polyester. At that, chemical structural formula: (Here, R represents an ethyl group or a methyl group) The film (A) contains less than 0.08% by weight of the organic compound relative to the film (A), and the film (B) contains less than 0.08% by weight relative to the film (B). A laminated polyester film containing 0.08 to 1.2% by weight, and characterized in that both films (A) and (B) of the laminated film are biaxially stretched and have an ultraviolet transmittance of 25 to 65% at a wavelength of 350 mμ.