WO2014059496A1

WO2014059496A1 - Method for producing reflective laminates for thermal and solar radiation control, and resulting products

Info

Publication number: WO2014059496A1
Application number: PCT/BR2013/000396
Authority: WO
Inventors: Antonio Sergio ASSUNÇÃO TAVARES
Original assignee: Assunç O Tavares Antonio Sergio
Priority date: 2012-10-16
Filing date: 2013-10-04
Publication date: 2014-04-24
Also published as: BR102012026435A2

Abstract

The invention relates to a method for producing reflective laminates for thermal and solar radiation control, and to the resulting products, namely plastic laminated reflective films (AR), embossed laminated reflective films (ARg), embossed and perforated laminated reflective films (ARgp), adhesive reflective laminates (LR) (industrial application), embossed adhesive reflective laminates (LRg) or embossed and perforated adhesive reflective laminates (LRgp), which can be used to manufacture outer envelopes (roofs, outer walls, window or door curtains) of enclosed spaces such as buildings, vehicles, containers, protected or unprotected cultures (greenhouses, tunnels, mulching), inter alia; also disclosed are protective "thin films" vacuum-deposited on a plastic film substrate and having special characteristics that increase the durability of the reflective laminate in that they improve resistance to UV radiation, mechanical attrition, moisture, chemicals, inter alia, ensuring the preservation of the outer metallisation layer and hence constant thermal control.

Description

"PRODUCTION PROCESS OF REFLECTIVE LAMINATE FOR CONTROL OF HEAT AND SOLAR RADIATION AND RESULTING PRODUCTS".

APPLICATION FIELD

The present patent relates to the process of producing reflective laminates for control of thermal and solar radiation and resulting products where, notably said reflective laminate with metallic surface constitutes a barrier to solar and thermal radiation, being used in the outer wraps (ceilings, external walls, window blinds, doors) of confined environments such as buildings, vehicles, containers, protected or unshielded crops (greenhouses, "small tunnels", "mulching") and others; and includes protective "thin films" vacuum deposited on plastic film substrate with special characteristics that promote durability to the reflective laminate through resistance to UV radiation, mechanical abrasion, moisture, chemicals, among others, ensuring the preservation of external metallization and, consequently, constant thermal control.

TECHNICAL BACKGROUNDS

Thermal insulators are materials that considerably inhibit heat transmission. Heat (vibration of molecules) can propagate directly as this vibration increases that of adjacent molecules; by convection (liquids and gases), when the molecules also move forming currents that accelerate the transmission process; and by radiation (emission of energy in the form of electromagnetic waves), which also acts in a vacuum and allows the warming of the earth and the existence of life.

The so-called "thermal insulators", which we will treat here as "traditional thermal insulators", may come from "natural" (cork, feathers, animal skins) or "industrial" origin: rock wool, glass wool, ceramic fiber, etc. , feature small air pockets naturally or artificially developed confined cells that slow the passage of heat and inhibit convection. They are inefficient at blocking radiant heat. These thermal insulators account for almost all commercial use and are generally applied to blankets or plates several centimeters thick.

There is another class of thermal insulators, called "reflective insulators", characterized by having a low emissivity surface that alters the flow (passage) of electromagnetic energy.

The emission of electromagnetic waves is a fundamental characteristic of matter, being the rate of energy emitted by radiation a function exclusively of the Temperature and Emissivity of its surface (Planck's Law). Their performance in heat transmission can be obscured in the usual situations where bodies have temperatures and near emissivities - the radiation they emit is offset by the radiation they receive. An analogy can be made here with atmospheric pressure, which goes unnoticed in most situations, although it has significant values, as found in the design of a vacuum chamber.

This energy exchange compensation does not occur when using "reflective insulators" due to their characteristic emissivity. While most materials usually have a high emissivity, between 0.7 to 0.9, in reflective films it is less than 0.1. Thus, if applied to the underside of a sun-heated tile, the heat absorbed by it will be radiated inward at a rate approximately eight times lower than outward so that it will act as a thermal insulator. If the reflective surface is exposed to solar radiation, such as curtains, it will reflect 90% of the incident radiation to the outside (in the usual situation of a body under rough thermal equilibrium conditions, emissivity and reflectivity are complementary values: 10% emissivity corresponds to some 90% reflectivity).

The first product based on a reflective insulator (polished silver) was the "Dewar Flask", which he invented in 1892 for his research on liquefied gases; was the precursor of the well-known thermos flask. The industrial lamination of aluminum (1930s) led to other uses, such as under-roofing and insulating blankets in which it was associated with glass wool. But; The breakthrough occurred during the space race, with the development of special plastic films and the process of their high vacuum metallization. In space (negative 273 ° C), due to the absence of convection, these metallized films have remarkable thermal performance, equivalent to a conventional insulator over 2 meters thick; constitute the standard thermal insulation of spacecraft, space suits, and satellites.

Metallized film was considered a military secret as thermal insulation, but its use in food packaging and decorative papers was authorized, generating huge development of the technologies involved.

With the end of the legal period of secrecy the product was released by NASA, arousing the interest of numerous inventors. But the metallized film deteriorated rapidly under normal use, with the presence of UV, moisture, abrasion, chemical washes, and others. The attempt to protect the metallized by applying varnishes or lamination with protective plastic films, the usual processes in flexible packaging, was unsuccessful, as they greatly increase emissivity, eventually nullifying thermal performance.

Thus, the development of this type of insulators was conditioned to the existence of metallized protection maintain their low emissivity characteristic. Depositions of "thin films" such as those cited in the applicant's own application PI 0205352-7 were tested in the laboratory and found promising and viable solutions. But the industrial development of the product, deepening the knowledge of the real conditions of its use, indicated the necessity of complementary solutions, described below, that guarantee the durability of the products, and attend to other desirable characteristics for the different types of use, not considered. previously. As the use in curtains corresponds to the most advanced industrial development product, most additions correspond to your specific needs; probably in the development of laminate for other uses we will detect new needs. The new features incorporated into the product and considered in this order are listed below and will be further defined below, based on Figure 1 for "Reflective Product Production Flow":

1) Additional UV Protection - The protection of metallized through "thin films" considered in the previous application has proved insufficient in some situations. The solution was a) to use UV-additive plastic substrate; and b) depositing aluminum on both sides of the reflective film.

2) Diffuse Reflection - Specular reflection of reflective laminate can generate unwanted reflections to the outside, as in the case of curtains. Its treatment through the embossing process provides diffuse reflection with little loss of thermal performance.

3) Drilling Application - Drilling the surface of the laminate proved to be very advantageous in the case of curtains, as well as the application of adhesive film in products already manufactured as containers, vehicles, containers, canvas, helmets, etc. and also for packing fruit and vegetables.

4) With Anti-Flame Properties - The plastic film to be metallized will receive additives so as not to spread flames; 5) "Self-cleaning" surface - Required when the reflective surface is periodically washed, such as when exposed to inclement weather.

TECHNICAL STATE ANALYSIS

The applicant, active in the field of product development with reflective films, is the holder of document # 2. PI 0205352-7 which deals with thermal and solar radiation control films which refers to a family of micrometer thickness plastic film films which receive surface treatment by the deposition of vacuum thin films which are capable of controlling, selectively, solar and thermal radiation, providing the desired thermal control effects. Radiation control is achieved through metallic reflection effects or optical filters, the film being applied industrially and generally in flexible coiled materials such as plastic films, plastic sheeting, nonwovens. , pre-painted or unpainted fabric, sheet metal, paper, paperboard and others, so as to lend the radiation control characteristics to these materials as economically as possible; the face in contact with the support (product to be coated) may receive treatment that facilitates the bonding of the same, possibly receiving deposition of specific thin film for this purpose. This bonding with the support (product to be coated) can be made by thermal welding, to reduce costs, or through industrial laminators, such as those used in the manufacture of flexible packaging.

The above application considered the "fabric" as a laminate with an aluminized plastic film on the outer face. To be durable, this metallization would be protected from UV radiation, mechanical abrasion, and the application of any moisture and chemicals (curtain cleaning) by the application of "thin films" (name used in physics to name the deposition of materials in very thin layers, high vacuum) on its surface, able to reflect UV radiation and protect the metallics from moisture, chemicals, and mechanical abrasion.

BRIEF DESCRIPTION OF THE INVENTION

Thus, after analyzing the state of the art and aiming to present a reflective laminate provided with elements that enable durability, the applicant developed improvements introduced in the process of obtaining reflective laminates for thermal control whose claimed innovations promote improvements related to durability, application, handling, etc, which are:

• substrate preferably made of plastic film with anti-UV additives;

• extra metallization applied to the inner face of the film;

• drilling suitable for various types of uses;

• mechanical treatment applied to the reflective laminate by embossing or other suitable process transforming the undesirable specular reflection typical of metallized film into diffuse reflection, to make them almost imperceptible;

• plastic film, adhesives, and other additive substrates with flame retardant products;

• plastic film substrate with suitable treatment for graphic printing;

• plastic film substrate with proper treatment to allow its bonding by means of contact adhesive tapes;

• treatment designed to provide "self-cleaning" surfaces where the laminate is exposed directly to the weather.

Thus, there are several advantages to the innovative reflective laminate, such as the durability of the film. Metallic material developed using the substrate made of plastic film with anti-UV additive.

Another advantage lies in the fact that the reflective laminate can be made into modules and provide easy joining between them, since the non-metallized faces have the surface in plastic film, allowing easy joining / joining by double-sided tape, eliminating the seams .

Another advantage, obtained through an additional step during the manufacture of the reflective laminate, is that it provides multiple laser or mechanical drilling with maximum dimensions suitable for light refraction at the edges, allowing the reflective laminate, even if fully extended, enable minimal natural lighting in diffused light.

Other additional advantages are relative to the constructivity of the laminate and may be cited as containing: (i) specular reflection; (ii) anti-flame qualities; (iii) possibility of graphic printing; and (iv) self-cleaning surface.

In the present application, some protections and some additional effects on the laminate were adopted:

1) Additional UV Protection of metallized plastic film. The "thin films" that protect the metallized film from UV can eventually be removed by abrasion, in areas that suffer movement and friction, as occurs in curtains; the industrial process itself can cause some "scratches" on the metallized. In these areas, although small, UV rays deteriorate the plastic, initiating the peeling of the aluminum film at the edges. In addition, abrasion and "scratching" are unacceptable in products such as curtains as they become apparent when the sun falls on them, to the detriment of aesthetic qualities. Thus, the present invention now uses a) additive plastic film substrate to resist UV b) an extra metallization on the inner face of the film (glued to the laminate substrate), which eliminates the visibility of any removals of the metallized one. 2) Drilling - Drilling the surface of the laminate is very advantageous in many cases. This drilling can be done by laser, or mechanically, by pinned rollers acting cold or hot. It has been found that when the substrate is a quality plastic film, preferably of high density, it permits perfect and durable drilling, in the desired diameters, obtained even by the simplest and cheapest process of cold pin drilling; The laminate also retains its tear resistance.

In the case of curtains, it is ideal that they allow the passage of part of the natural light (preferably in the form of diffused light), and a certain eye contact with the exterior, which eliminates any feeling of confinement. This is the case with curtains that employ fabrics like "solar screens", whose web of spaced wires allows the passage of a portion of sunlight. Due to the small size of the spaces, the light refracts at the edges of the strands, spreading evenly, creating a diffused light surface, already a short distance from the fabric. When these "solar screens" were initially imported, the void area was between 5% and 15% of the total area, which proved excessive for our climate; Today the screen of these screens corresponds to the area of voids ranging from 1% to 5%.

In tests, it was observed that a hole with small diameter holes (approximately 0.6 mm to 1.0 mm), easy to obtain even by the simplest and cheapest cold drilling process, reproduces the effect of these solar screens. . This was found in practice with a 3% void curtain sample, holes with a diameter of 0.8 mm, arranged in a 4x4 mm grid, placed in a window on the west face; the direct illumination thus filtered (3% of the intensity of direct sunlight) does not caused discomfort. Note that for energy saving purposes, as the reflection provided by the curtains of the present invention is proportional to its area, the loss of thermal performance would be only 3%.

In addition to the initially designed curtain application, object of the invention, another advantageous application of this invention occurs in the transport and packing of fresh produce, the holes allow their "breathing" and the release of water vapor, increasing their useful life.

Another application is mulching in extensive agricultural crops that help to drain rainwater or irrigation.

In cases where the metallized film is bonded with contact adhesives, for placement on products already manufactured such as vehicles, containers, helmets, bags, and others, the holes help to eliminate the usual air bubbles that appear during its application.

3) Diffuse Reflection - Metallic curtain film can generate unwanted reflections to the outside when the reflection is specular (smooth surfaces). The metallized treatment through the much used "embossing" process (relief of the surface obtained by mechanical compression) allows controlled variations of the inclination of this surface with millimeter spacing, in order to make the reflection more diffuse, with little loss of thermal performance. (of the order of 5% in the samples tested). This diffuse reflection is also useful when using the laminate as a solar reflector in greenhouses (it reflects light that would be lost in the soil to the plants, increasing productivity and obtaining fruits of homogeneous size), according to tests performed in greenhouses.

4) Anti-flame properties - The advantages of good fire behavior are obvious, especially in cases such as curtains. Thus, all materials used - reflective film, plastic substrate, adhesives - will be added with flame retardants during their manufacture. Seemingly simpler solutions, such as applying a flame varnish, do not provide satisfactory results in flame propagation tests. The pattern considers exposing the curtain to a torch flame long enough for all of its components to reach high temperatures; surface protection will be insufficient. Passing the test requires that the material without burning weighs at least 50% of the sample weight, among other requirements.

5) Graphic Printing - One of the advantages of the technologies used in the manufacturing of reflective packaging is the ease of obtaining excellent quality graphic printing at low cost, as can be seen in a supermarket. The aesthetic appearance of a curtain is therefore of the utmost importance, and if the substrate is a quality plastic, preferably treated with the corona process, the apparent face may receive the impression of the desired patterns or smooth colors of excellent quality. and very low prices.

6) Easy Bonding Tapes - Contact tapes, both in the form of double sided tapes and glue transfer tapes, greatly simplify industrial processes. In the present case, when the substrate is a quality plastic, preferably treated with the "corona" process, laminate strips may be joined by these tapes, as the other metallised face has excellent qualities for this type of joint. . This eliminated seams, a more complicated and expensive industrial process that requires more labor. These tapes will also be used to attach the laminate to its supporting parts such as roller blinds etc.

7) "Self-Cleaning" Surface - The effect of a reflective film diminishes as its surface is covered with dust or dirt. It is This occurrence, nonexistent in spatial uses and cryogenics, is always present in our case and should always be considered in the development of the products. We verified that:

• Since the metallized surface of the film has no static electricity, dust does not accumulate on it except for the effect of gravity. Thus, the underside of a metallised film tile, or the underside of an underlay, is clean after years of use, despite the high occurrence of dust. Already on the upper face of an underlay, even if metallized, the dust accumulates quickly.

• On a vertical metallic surface such as a curtain, dust accumulation occurs due to small irregularities (such as those produced by embossing), but in minimal amounts, and is easily removed with a duster.

• In the case of periodically sanitized metallized surfaces, when applied inside food transport trucks, poultry linings, and others, this mandatory cleaning removes dust.

• When the reflective surface is exposed to the weather, such as "reflective mulching", we have the worst situation, with rain cleaning.

Note that the main purpose of "reflective mulching" is to lower soil temperatures and provide cooler (more lucrative) climate crops, which can only be achieved by metallization of the inner (protected) face. But if we want the additional effect of reducing global warming, the upper face must reflect solar radiation, and be "self-cleaning" with rain. The potential importance of this use is attested by several studies in especially in the USA, to produce crops with more reflective foliage that increase terrestrial albedo (ratio of reflected solar energy to incident), reducing global warming.

There are two apparently contradictory ways to get a "self-cleaning" surface:

a) Provide the surface with an appropriate roughness (very high contact angle and very low "roll I off" angle) that repels moisture and dirt (hydrophobic surface) as the water droplets formed by surface tension they are suspended over the "peaks" of the surface and roll over it.

Our proposal is to "sculpt" the surface of the plastic film before depositing the "thin films", which do not influence the roughness due to its nanometer thickness. This can be achieved by dry etching processes such as ion etching. This process is very similar to that used for sputtering deposition of "thin films", except that ions are directed here directly onto the plastic film substrate, causing the roughness.

b) Treat the surface with products that reduce the surface tension of the water, so that it runs easily on water-laden soil (hydrophilic surface). This can be achieved by coatings of various materials such as titanium dioxide.

The preference for one solution or another will depend on testing for corresponding thermal performance losses, industrial execution difficulties, and related costs.

DESCRIPTION OF DRAWINGS

In addition to the present description in order to gain a better understanding of the features of the present invention and according to a preferred practical embodiment thereof, accompanies the Here is a description of a set of drawings, in which, by way of example, although not limiting, its operation was represented:

Figure 1 shows a schematic view of the process of producing reflective laminates for thermal and solar radiation control, illustrating the possibilities of composition and final products.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the related drawings, the present invention relates to "REFLECTIVE LAMINATE PRODUCTION PROCESS FOR CONTROL OF TERMS AND SOLAR RADIATIONS AND RESULTANT PRODUCTS", more precisely it is a process for obtaining plurality of reflective products of the type which includes a substrate (S) in the form of plastic film (1) which has the deposition of at least one external metallization layer by vacuum deposition of aluminum thin film (MET), substrate (S) known to control, selectively, solar and thermal radiation, providing the desired thermal control effects.

According to the present invention, the reflective laminate production process (1) comprises the following steps:

Step a - sputtering metallization - the substrate (S) receives, on one of the surfaces (MET) the sputtering metallization of aluminum protective thin films (2), forming a reflective film (FR);

Step b - Adhesive Lamination (3)

Step bl - The reflective film (FR) receives, on the opposite surface to the aluminum shield (2), a contact adhesive (4) plus a protective plastic film, composing the Reflective Reflective Film (AR);

Step bl.l - embossing application - relief printing on the Adhesive Reflective Film (AR) by mechanical compression (7), composing the Embossed Reflective Film (ARg); Step bl.2 - Drilling application - Drilling the Adhesive (AR) or Embossed Reflective Film (ARg) by mechanical means (8) (cold or hot pin drilling) or by laser (9), obtaining Film Embossed (or not) and perforated (ARp) or (ARgp) reflective;

Step b2 (variation from step bl) - The Adhesive Reflective Film (AR) receives a lamination adhesive (5) and a flexible substrate (6), such as canvas, plastic, non-woven, among others, composing the Reflective Laminate ( LR) and resulting in coils of these treated materials;

Step b2.1 - Embossing application - relief printing on the Reflective Laminate (LR) by mechanical compression (7), composing the Embossed Reflective Laminate (LRg);

Step bl.2 - drilling application - drilling of the reflective (LR) or embossed (LRg) laminate by mechanical means (8) (cold or hot pin drilling) or by laser (9), obtaining Reflective Laminate embossed (or not) and perforated (LRp) or (LRgp).

Plastic film (1), as well as adhesives (4), and other substrates may be added with products with flame retardant properties.

The substrate (3) made of plastic, woven or other film may be suitably treated to receive graphic printing.

The substrate (3), particularly of plastic film, may be adequately treated to allow bonding by means of contact adhesive tapes, allowing it to be installed in appropriate locations.

The resulting products in the form of Reflective Laminate and / or Reflective Laminate, adhesive, embossed and / or perforated film are treated to provide "self-cleaning" surfaces. The reflective products obtained in the steps described above and some of their applications can be defined as follows:

- Reflective Plastic Laminated Film - (AR) - used as reflective canvas, mulching and other applications;

- Embossed Laminated Reflective Film (ARg) - used as a blackout curtain, as a solar reflector in agricultural greenhouses and other applications;

- Punch Embossed Laminated Reflective Film (ARgp) - applied as a "solar screen" curtain for other applications;

- Reflective Adhesive Laminate (LR) (industrial application) - Pre-painted sheets; thermal tiles; vehicle bodies, Dry-Wall panels, Brises and Revest, Sheet metal; Tarpaulins (closing trucks), food transportation, poultry houses, among others;

- Embossed Reflective Adhesive Laminate (LRg) - Blackout curtains and others;

- Embossed and Perforated Reflective Adhesive Laminate (LRgp) - Applied in containers, trunk trucks, canvas, helmets, bags and others.

Admittedly, when the present invention is put into practice, modifications may be made with respect to certain details of construction and shape, without implying departing from the fundamental principles which are clearly substantiated in the claim framework, thereby understanding that The terminology used was for non-limitation purposes.

Claims

1) "REFLECTIVE LAMINATE PRODUCTION PROCESS FOR CONTROL OF HEAT AND SOLAR RADIATION AND RESULTANT PRODUCTS", more precisely, is a process for obtaining a plurality of reflective products, such as a substrate (S) in the form of plastic film (1) provided with the deposition of at least one external metallization layer by vacuum deposition of aluminum thin film (MET), substrate (S) known to be capable of selectively controlling solar and thermal radiation, providing the effects of desired thermal control; characterized in that the reflective laminate production process (1) comprises the following steps:

Step b - Adhesive Lamination (3)

Step bl.l - embossing application - relief printing on the Adhesive Reflective Film (AR) by mechanical compression (7), composing the Embossed Reflective Film (ARg);

Step bl.2 - Drilling application - Drilling the Adhesive (AR) or Embossed Reflective Film (ARg) by mechanical means (8) (cold or hot pin drilling) or by laser (9), obtaining Film Embossed (or not) and perforated (ARp) or (ARgp) reflective;

Step b2 (variation from step bl) - The Adhesive Reflective Film (AR) receives a lamination adhesive (5) and a flexible substrate (6), such as canvas, plastic, non-woven, among others, composing the Reflective Laminate ( LR) and resulting in coils of these treated materials; Step b2.1 - Embossing application - relief printing on the Reflective Laminate (LR) by mechanical compression (7), composing the Embossed Reflective Laminate (LRg);

"PROCESS" according to Claim 1, characterized in that the plastic film (1) as well as the adhesives (4) and other substrates are or are not additive with products with flame retardant properties.

"Process" according to claim 1, characterized in that the substrate (3) of plastic film, fabric or other material is or is not properly treated in order to receive graphic printing.

"PROCESS" according to Claim 1, characterized in that the substrate (3), particularly of plastic film, is or is not properly treated to allow its bonding by means of contact adhesive tape, allowing its installation in appropriate locations. .

"PROCESS" according to Claim 1, characterized in that the resulting products in the form of Reflective Laminate and / or Reflective Laminate, adhesive, embossed and / or perforated film are treated to provide "self-cleaning" surfaces.

6. "RESULTING PRODUCTS", characterized in that reflective products obtained by the process of claim 1 are thus defined:

- Plastic Laminated Reflective Film - (AR);

- Embossed Laminated Reflective Film (ARg);

- Embossed Laminated Reflective Film with Hole (ARgp);

- Reflective Adhesive Laminate (LR) (industrial application);

- Embossed Reflective Adhesive Laminate (LRg);

- Embossed and Perforated Reflective Adhesive Laminate (LRgp). 7. "RESULTING PRODUCTS" according to the preceding claims, characterized in that the metallization layer (MET) is internal to the thin films (2) of transparent plastic.

"RESULTANT PRODUCTS" according to claim 1, characterized in that the backing film (1) is of a reduced thickness, generally between one and three tens of microns or less.

"RESULTANT PRODUCTS" according to claims 1 and 6, characterized in that the embossing is formed by microspheres of various configurations.

10. "RESULTING PRODUCTS" according to claims 1, 6 and 9, characterized in that the micro reliefs have decorative motifs.

11) "RESULTING PRODUCTS" according to the preceding claims, characterized by Plastic Laminated Reflective Film (AR) or Embossed Laminated Reflective Film (ARg) or Drilled Embossed Laminated Reflective Film (ARgp) or Reflective Adhesive Laminate (LR) (application Embossed Reflective Adhesive Laminate (LRg) or Embossed Reflective Adhesive Laminate (LRgp) can be used to make external wraps (ceilings, exterior walls, window blinds, doors) from confined environments such as buildings, vehicles, containers , protected or unprotected crops (greenhouses, "small tunnels", "mulching") and others.