Use of particulate titanium dioxide for reducing the transmission of near-infrared radiation

Abstract

Disclosed is the use of a particulate material in a polymer article, or a polymer composition containing the particulate material, in particular a masterbatch, as well as of a polymer film composition, for reducing the transmission of near-infrared radiation and for allowing transmission of visible light through the article, whereby i. the particulate material is based on crystalline titanium dioxide, ii. the particles of the particulate material are coated with an organic and / or inorganic coating layer, iii. at least 20% by weight of the particulate material particles have a particle size of at least 400 nm and at most 1000 nm, and iv. at least 1.5% by weight and at most 40% by weight of the particles in the particulate material have a particle size of less than 400 nm and at least 280 nm.

Description

technical field [0001] The present invention relates to the field of making polyolefin films. More specifically, the invention relates to the manufacture of a film that has a low transmittance for infrared radiation but diffusely transmits most of the visible light. Background technique [0002] Prolonged exposure to sunlight generally has damaging effects on most physical entities. Therefore, under large temperature fluctuations, the color of objects fades rapidly, and many materials may appear distorted and deformed. Prolonged exposure degrades many materials and their aesthetic aspects (commonly referred to as "aging"), typically resulting in reduced useful life and the need for replacement. Plants, animals and humans also tend to be negatively affected by prolonged exposure to sunlight. Therefore, shielding from sunlight becomes an important feature in many cases. [0003] In solar radiation, about 45% of its energy is visible light in the relatively narrow range of ...

AI Technical Summary

Problems solved by technology

The disadvantage of these membranes is that the absorbed radiation is converted into heat in the membrane

Therefore, this absorption may result in a localized temperature increase that is transferred to the substrate onto which the film is applied

For many substrates, such as glass, this localized temperature increase leads to high mechanical stress and may even lead to glass breakage

A second disadvantage is that the absorbed heat, although transmitted in a more uniform manner to the interior, can still locally lead to a large temperature increase that is still undesirable

The disadvantage of this screen is that part of the visible light is reflected and thus part of the PAR radiation is reflected

When applied to a greenhouse, this covering material may have the disadvantage that the part of visible light that is not available to plants is transmitted and converted into heat, while other parts that are available to plants (such as the red part) are reflected

Disadvantages of the membranes proposed in WO96 / 03029 are that their manufacture is complicated and the selected polymer material is rather rare

Reflection of radiation Another disadvantage of interference-based films is that their performance depends on the angle of incidence of the radiation, in this case the position of the sun relative to the orientation of the film

These membranes are more complex than those discussed above

Therefore, these membranes suffer from the same disadvantages of limited acceptance in terms of field of application

[0023] The disadvantage of these interference-based techniques is that each application may require a membrane specifically designed for that application

Therefore, a specific membrane may only work well in a very specific application

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