Greenhouse screen
AssigneeAB Ludvig Svensson
InventorsPer HOLGERSON, Daniel ASPLUND
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Abstract
A greenhouse screen comprising strips of film material that are interconnected by a yarn system of transverse threads and longitudinal threads by means of a knitting, warp-knitting or weaving process to form a continuous product is provided. At least some of the strips comprise a polyester film having a transparency of at least 93%, said polyester film having at least one base layer B comprising a thermoplastic polyester and a UV stabilizer. The polyester film has a first and a second surface, wherein a permanent anti-fog coating is applied to at least one of the first or second surfaces of the polyester film. The anti-fog coating has a lower refractive index than the base layer B.A process for producing said film is also disclosed.
Claims28
A greenhouse screen comprising strips (11) of film material that are interconnected by a yarn system of transverse threads (12, 14, 18) and longitudinal threads (13a, 13b;
- 15;
- 19) by means of a knitting, warp-knitting or weaving process to form a continuous product, wherein at least some of the strips (11) comprise a polyester film having a transparency of at least 93%, said polyester film having at least one base layer B comprising a thermoplastic polyester and a UV stabilizer, said polyester film has a first and a second surface, wherein a permanent anti-fog coating is applied to at least one of the first or second surfaces of the polyester film, and characterized in that said anti-fog coating has a lower refractive index than the base layer B.
The greenhouse screen according to any one of the preceding claims, characterized in that the base layer B consists of at least 70% by weight of a thermoplastic polyester, the thermoplastic polyester comprising at least 85 mol %, such as at least 90 mol % such as at least 92 mol % units derived from ethylene glycol and terephthalic acid.
The greenhouse screen according to any one of the preceding claims, characterized in that the polyester film has a Standard Viscosity (SV) value greater than 600, such as greater than 650, such as greater than 700, the SV value of the film being less than 950, such as less than 850.
The greenhouse screen according to any one of the preceding claims, characterized in that the UV stabilizer is selected from the group consisting of triazines, benzotriazoles, benzoxazinones, and the base layer B and, if present, the layer A and/or the layer C contain the UV stabilizer in an amount of 0.3 to 3% by weight, such as 0.75 to 2.8% by weight, based on the weight of the respective layer.
The greenhouse screen according to any one of the preceding claims, characterized in that the refractive index of the anti-fog coating is below 1.64, such as below 1.60 such as below 1.58 at a wavelength of 589 nm in the machine direction of the film.
The greenhouse screen according to any one of the preceding claims, characterized in that the thickness of the anti-fog coating is at least 60 nm and at most 150 nm, such as at least 70 nm and at most 130 nm, such as at least 80 nm and at most 120 nm.
The greenhouse screen according to any one of the preceding claims, characterized in that the anti-fog coating is a dispersion composition and comprises,
- a) a hygroscopic, porous material;
- b) a polymer-based crosslinker;
- c) an adhesion-promoting organofunctional silane;
- and
- d) one or more surfactants.
The greenhouse screen according to any one of the preceding claims, characterized in that the anti-fog and/or anti-reflective coatings are applied in-line during production of the biaxially oriented polyester film.
The greenhouse screen according to any one of the preceding claims, characterized in that the anti-fog and/or anti-reflective coatings are applied to the first and/or second surfaces of the polyester film by means of off-line technology in an additional process step downstream of the film production.
The greenhouse screen according to any one of the preceding claims, characterized in that one or more of said strips of film material (11) has a width that is smaller than the distance between the longitudinal threads (13a, 13b;
- 15;
- 19).
The greenhouse screen according to any one of the preceding claims, characterized in that at least 10%, preferably at least 20%, more preferably at least 30%, more preferably at least 40%, more preferably at least 50%, more preferably at least 60%, more preferably at least 70%, more preferably at least 80%, more preferably at least 90% of the strips of film material (11) in the greenhouse screen comprise said single- or multilayer polyester film.
The greenhouse screen according to any one of the preceding claims, characterized in that all strips of film material (11) in the greenhouse screen are of said single- or multilayer polyester film.
Use of the greenhouse screen according to any one of the preceding claims as a convection barrier.
Dependencies are inferred from the claim text.