Composite thermal insulator

Abstract

The present invention discloses a composite thermal insulator including a first transparent substrate layer, a second transparent substrate layer, and a near-infrared shielding layer positioned between the first transparent substrate layer and the second transparent substrate layer, and the near-infrared shielding layer is formed by dispersively fixing multiple nanoparticles containing tungsten oxide in polyethylene terephthalate. The composite thermal insulator can't change color under sunlight so that it can be used for light output controlling and thermal isolation.

Claims

1. A method for making composite thermal insulator, having a color change ratio of less than 1% transparent, comprising: providing a first transparent substrate layer, a second transparent substrate layer; co-extruding and providing a near-infrared shielding layer which is positioned between the first transparent substrate layer and the second transparent substrate layer and formed by dispersively fixing multiple nanoparticles containing tungsten oxide in polyethylene terephthalate, a first protection layer which is positioned between the first transparent substrate layer and the near-infrared shielding layer, and a second protection layer which is positioned between the second transparent substrate layer and the near-infrared shielding layer, wherein the first protection layer is a pure polyethylene terephthalate layer, and the second protection layer is a pure polyethylene terephthalate layer; irradiating with ultraviolet light having a wavelength of 310 nm and an intensity of 0.63 W/m.sup.2 for 8 hours; condensing by water at 50 C. for 4 hour; and treating with repeated cycles of the ultraviolet light irradiation and water condensation for more than 500 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a section view illustrating a composite thermal insulator according to a first embodiment; and

(2) FIG. 2 is a section view illustrating a composite thermal insulator according to a second embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(3) Other features and advantages of the invention will become apparent in the following detailed description of a preferred embodiment with reference to the accompanying drawings.

(4) As shown in FIG. 1, a composite thermal insulator according to a first embodiment of the present invention is depicted. This composite thermal insulator has properties of heat isolation and color stability so as to be used for thermal insulation and light output controlling. The composite thermal insulator at least includes a first transparent substrate layer (11), a second transparent substrate layer (12), a near-infrared shielding layer (13), a first adhesive layer (14), and a second adhesive layer (15).

(5) The first transparent substrate layer (11) and the second transparent substrate layer (12) are structurally supportive to the composite thermal insulator, and they may individually be a glass layer, a polycarbonate layer, or a polymethyl methacrylate layer. In addition, the first transparent substrate layer (11) and the second transparent substrate layer (12) may individually have a thickness of 2-19 mm.

(6) The near-infrared shielding layer (13) is positioned between the first transparent substrate layer (11) and the second transparent substrate layer (12) and is formed by dispersively fixing multiple nanoparticles containing tungsten oxide in polyethylene terephthalate. Polyethylene terephthalate can prevent tungsten oxide from reaction with electrons and protons so that the composite thermal insulator can isolate heat without color change. The near-infrared shielding layer (13) may have a thickness of 12-250 m, and preferably of 18-100 m. Based on total weight of the near-infrared shielding layer (13), the nanoparticles may have an amount of 0.01 wt %-20 wt %, and the polyethylene terephthalate may have an amount of 80 wt %-99.99 wt %. Additionally, the nanoparticles may be dispersively fixed in the polyethylene terephthalate in an amount of 0.01-10 g/m.sup.2 of the polyethylene terephthalate. Further, an example of the nanoparticle is a nanoparticle containing tungsten suboxide, tungsten trioxide, or tungsten bronze. Tungsten suboxide is represented by a formula of WO.sub.N, wherein W indicates a tungsten atom, O indicates an oxygen atom, x indicates a number of the oxygen atom, and 2.2x<3. Tungsten bronze is represented by a formula of A.sub.yWO.sub.z, wherein A indicates a main-group atom (for example, a lithium atom, a sodium atom, a potassium atom, a rubidium atom, a cesium atom, a magnesium atom, a calcium atom, a strontium atom, a barium atom, an aluminum atom, a gallium atom, a carbon atom, a silicon atom, a tin atom, an antimony atom, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), W indicates a tungsten atom, O indicates an oxygen atom, y indicates a number of the main-group atom, 0.1y<1, z indicates a number of the oxygen atom, and 2.2z<3.

(7) The first adhesive layer (14) is positioned between the first transparent substrate layer (11) and the near-infrared shielding layer (13) and can provide adhesion on the first transparent substrate layer (11) for the near-infrared shielding layer (13). The first adhesive layer (14) may have a thickness of 0.38-0.76 mm, and an example thereof is a polyvinyl butyral film, an ethylene vinyl acetate film, or a polyurethane film. It is noted that polyvinyl butyral not only can enhance the adhesion ability, but also has properties of heat proof, chill proof, humidity proof, and high mechanical strength so as to increase application value of the composite thermal insulator.

(8) The second adhesive layer (15) is positioned between the second transparent substrate layer (12) and the near-infrared shielding layer (13). It is noted technical features and functions of the second adhesive layer (15) refer to the previous description for the first adhesive layer (14), and there is no further description thereon.

(9) As shown in FIG. 2, a composite thermal insulator according to a second embodiment of the present invention is depicted. The present composite thermal insulator substantially has the same technical features and functions as those of the previous composite thermal insulator, but their differences are described as below:

(10) Between the first transparent substrate layer (11) and the near-infrared shielding layer (13) is a first protection layer (16), and between the second transparent substrate layer (12) and the near-infrared shielding layer (13) is a second protection layer (17). These protection layers (16, 17) can ensure no contact of electrons and protons with the nanoparticles containing tungsten oxide so that the oxidation-reduction reaction can't take place. By such a way, the color stability can be ensured. Specifically, the first protection layer (16) is positioned between the first adhesive layer (14) and the near-infrared shielding layer (13), and the second protection layer (17) is positioned between the second adhesive layer (15) and the near-infrared shielding layer (13). Examples of the first protection layer (16) and the second protection layer (17) are individually a polyethylene terephthalate layer. The polyethylene terephthalate layer can bring benefit that it can be formed with the near-infrared shielding layer (13) through a co-extrusion process to simplify the manufacturing process.

(11) The following examples are offered to further illustrate the invention:

(12) Any near-infrared shielding layers described in the following examples were made by the present inventor(s), and the manufacture referred to Taiwan Invention Patent Application No. 103120233; any polyvinyl butyral films and any ethylene vinyl acetate films described in the following examples were commercially available from Solutia, Trosifol, Sekesui, Dupont, Kingboard Chemical Holdings, Formosa Plastics, or Tex Year; any glass substrates described in the following examples were commercially available from Taiwanglass or AGC. Table 1 shows the structural compositions of various thermal insulators, and all layers are stacked in sequence.

(13) TABLE-US-00001 TABLE 1 composition and optical property of various thermal insulators Trans- mittance Composition (%) Example 1 Glass substrate with a depth of 2 mm/ 0.2 Polyvinyl butyral film with a depth of 0.38 mm/Near-infrared shielding layer with a depth of 18 m (containing WO.sub.2.72 nanoparticles)/Polyvinyl butyral film with a depth of 0.38 mm/ Glass substrate with a depth of 2 mm Example 2 Glass substrate with a depth of 3 mm/ 0.1 Ethylene vinyl acetate film with a depth of 0.38 mm/Near-infrared shielding layer with a depth of 18 m (containing WO.sub.2.72 nanoparticles)/ Ethylene vinyl acetate film with a depth of 0.38 mm/Glass substrate with a depth of 2 mm Example 3 Glass substrate with a depth of 5 mm/ 0.3 Polyvinyl butyral film with a depth of 0.38 mm/Near-infrared shielding layer with a depth of 23 m (containing Cs.sub.0.33WO.sub.3 nanoparticles)/ Polyvinyl butyral film with a depth of 0.38 mm/Glass substrate with a depth of 5 mm Example 4 Glass substrate with a depth of 6 mm/ 0.4 Ethylene vinyl acetate film with a depth of 0.38 mm/Near-infrared shielding layer with a depth of 23 m (containing WO.sub.2.72 nanoparticles)/ Ethylene vinyl acetate film with a depth of 0.38 mm/Glass substrate with a depth of 6 mm Example 5 Glass substrate with a depth of 10 mm/ 0.5 Polyvinyl butyral film with a depth of 0.76 mm/Near-infrared shielding layer with a depth of 50 m (containing Cs.sub.0.33WO.sub.3 nanoparticles)/Polyvinyl butyral film with a depth of 0.76 mm/ Glass substrate with a depth of 10 mm Example 6 Glass substrate with a depth of 12 mm/ 0.4 Ethylene vinyl acetate film with a depth of 1.14 mm/Near-infrared shielding layer with a depth of 50 m (containing Cs.sub.0.33WO.sub.3 nanoparticles)/ Ethylene vinyl acetate film with a depth of 1.14 mm/Glass substrate with a depth of 12 mm Example 7 Glass substrate with a depth of 15 mm/ 0.8 Polyvinyl butyral film with a depth of 1.52 mm/Near-infrared shielding layer with a depth of 100 m (containing Cs.sub.0.33WO.sub.3 nanoparticles)/Polyvinyl butyral film with a depth of 1.52 mm/ Glass substrate with a depth of 15 mm Example 8 Glass substrate with a depth of 19 mm/ 0.6 Ethylene vinyl acetate film with a depth of 1.52 mm/Near-infrared shielding layer with a depth of 188 m (containing Cs.sub.0.33WO.sub.3 nanoparticles)/ Ethylene vinyl acetate film with a depth of 1.52 mm/Glass substrate with a depth of 19 mm Comparative Glass substrate with a depth of 5 mm/ 27.3 Example 1 Polyvinyl butyral film with a depth of 0.76 mm (containing 0.2 wt % of Cs.sub.0.33WO.sub.3 nanoparticles)/Glass substrate with a depth of 5 mm Comparative Glass substrate with a depth of 6 mm/ 36.8 Example 2 Ethylene vinyl acetate film with a depth of 0.76 mm (containing 0.2 wt % of WO.sub.2.72 nanoparticles)/Glass substrate with a depth of 6 mm

(14) All thermal insulators were test for transmittance after being irradiated with ultraviolet light having a wavelength of 310 nm and an intensity of 0.63 W/m.sup.2 for 8 hours, being condensed by water at 50 C. for 4 hour, and then being treated with repeated cycles of the ultraviolet light irradiation and water condensation for more than 500 hours. The test result is shown in Table 1. Compared with the thermal insulators in comparative examples, the thermal insulators in examples have no color change and are substantially transparent.

(15) As described above, the thermal insulator of the present invention can't change color under sunlight. That is, it is a thermal insulator for light output controlling and can be used in any substances in need of thermal isolation.

(16) While the invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.