GB2447414A

GB2447414A - Sunlight control film

Info

Publication number: GB2447414A
Application number: GB0704961A
Authority: GB
Inventors: Chuan-Kuan Wei
Original assignee: RAINBOW PACKAGE IND CO Ltd
Current assignee: RAINBOW PACKAGE IND CO Ltd
Priority date: 2007-03-14
Filing date: 2007-03-14
Publication date: 2008-09-17
Anticipated expiration: 2027-03-14
Also published as: GB2447414B; GB0704961D0

Abstract

A sunlight control film which may be used on a window panel or lens 10 includes: a multi-layer laminate 11 including alternately disposed first and second base layers 111, 112, the total layer number of the first and second base layers 111, 112 being at least 20 and less than 400, each of the first and second base layers 111, 112 having a layer thickness ranging from 3800 to 8000 angstroms, the refractive index difference between the first and second base layers 111, 112 being greater than 0.03; and an invisible light absorbing layer unit 2 formed on the multi-layer laminate 11. The first base layer may be made from an acrylic-based resin and the second base layer may be made from a resinous mixture containing terephthalate-containing polymeric material such as PBT, polyethylene and optionally a copolymer of polybutylene terephalate and polyglycol (co-PBT). The invisible light absorbing unit may include an infra-red absorbing layer 12,containing a polycarbonate based resin and an infra-red absorbing agent e.g. antimony tin oxide or indium tin oxide or an ultra-violet absorbing layer 14 containing a polyacrylate-based resin and a benzotriazole as a UV absorbing agent. A wear resistant layer 14 containing a polyester-based resin and lanthanum hexaboride may also be present. The film exhibits excellent heat insulation while maintaining, satisfactory transparency.

Description

SUNLIGHT CONTROL FILM

The invention relates to a sunlight control film, more particularly to a sunlight control film including a multi-layer laminate coated with an infrared absorbing layer and an UV absorbing layer.

Conventional sunlight control films normally include a polyester substrate coated with an infrared (IR) absorbing layer and an ultraviolet (UV) absorbing layer so as to provide a heat insulation effect when used on a window panel or an optical lens. However, the heat insulation effect of the sunlight control films thus formed is relatively poor.

Therefore, the object of the present invention is to provide a sunlight control film that can provide an excellent heat insulation effect while maintaining a satisfactory transparency.

Accordingly, a sunlight control film comprises: a multi-layer laminate including alternately disposed first and second base layers, the total layer number of the first and second base layers being at least 20 and less than 400, each of the first and second base layers having a layer thickness ranging from 3800 to 8000 angstroms, the refractive index difference between the first and second base layers being greater than 0.03; and an invisible light absorbing layer unit formed on the multi-layer laminate.

Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawing, of which: Fig. 1 is a fragmentary schematic view of the preferred embodiment of a sunlight control film according to the present invention.

The preferred embodiment of the sunlight control film according to the present invention can be attached to an article 10, such as a window panel or an optical lens, asbest illustrated in Fig. 1, forproviding an excellent heat insulation effect while maintaining a satisfactory transparency. The sunlight control film of this invention includes: a multi-layer laminate 11 including alternately disposed first and second base layers 111, 112, the total layer number of the first and second base layers 111, 112 being at least 20 and less than 400, each of the first and second base layers 111, 112 having a layer thickness ranging from 3800 to 8000 angstroms, the refractive index difference between the first and second base layers 111, 112 being greater than 0.03; and an invisible light absorbing layer unit 2 formed on the multi-layer laminate 11.

In this embodiment, the invisible light absorbing layer unit 2 includes an infrared absorbing layer 12 formed on a first surface of the multi-layer laminate 12, andanUVabsorbinglayerl4 forrnedona second surface of the multi-layer laminate 12 that is opposite to the first surface of the multi-layer laminate 12.

Preferably, the total layer number of the first and second base layers 111, 112 is less than or equal to 200, and more preferably, ranges from 100 to 200.

Each of the first base layers 111 is made from an acrylic-based resin material, and each of the second base layers 112 is made from a resinous mixture containing a terephthalate-containing polymeric material and polyethylene.

The acrylic-based resin material suitable for the first base layers lii is made from a polymer polymerized by a monomer selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl acrylate, or froma copolymerpolymerizedbytheaforesajdmonomer and other monomer(s) . Preferably, the acrylic-based resin material is polymethyl methacrylate (PMMA) The terephthalate-containing polymeric material is preferably polybutylene terephthalate (PBT) Preferably, the resinous mixture further contains a copolymer of polybutylene terephthalate and polyglycol (c0PBT) . In this embodiment, the resinous mixture preferably contains 80 to 95 wt% of polybutylene terephthalate, 3 to 15 wt% of the copolymer of polybutylene terephthalate and polyglycol, and 0.5 to wt% of polyethylene, and more preferably, contains to 93 wt% of polybutylene terephthalate, 5 to 10 wt% of the copolymer of polybutylene terephthalate and polyglycol, and 1 to 4 wt% of polyethylene.

The polyethylene suitable for the second base layers 112 ispreferably linear lowdensitypolyethylene (LLDPE) having a density ranging from 0.85 to 0.93 and a melt index ranging from 1 to 50.

The sunlight control film preferably further includes a wear resistant layer 13 formed on a selected one of the infrared absorbing layer 12 and the tJV absorbing layer 14. In this embodiment, the wear resistant layer 13 is formed on the infrared absorbing layer 12. Thewearresistant layer l4preferablycontains a polyester-based resin and Lanthanumhexaboride (LaB6) dispersed in the polyester-based resin. The Lanthanum hexaboride is preferably present in an amount ranging from 0.1 to 0.3 wt% based on the total weight of the wear resistant layer 14. The wear resistant layer 14 preferably has a layer thickness ranging from 1 to 2 urn.

The infrared absorbing layer 12 preferably contains a polycarbonate-based resin and an infrared absorbing agent dispersed in the polycarbonate-based resin and made from a material selected from the group consisting of antimony tin oxide (ATO) and indium tin oxide (ITO).

The infrared absorbing agent is preferably present in an amount ranging from 0.5 to 1.0 wt% based on the total weight of the infrared absorbing layer 12, and has a particle size ranging from 100 to 150 nm. The infrared absorbing layer 12 preferably has a layer thickness ranging from 1 to l0m.

The UV absorbing layer 14 preferably contains a polyacrylate-based resin and an (iv absorbing agent dispersed in the polyacrylate-based resin and made from benzotriazoie. The UV absorbing agent is preferably present in an amount ranging from 0.3 to 0.7 wt% based on the total weight of the UV absorbing layer 14. The tJV absorbing layer 14 preferably has a layer thickness ranging from 1 to 5#m.

In this embodiment, the first base layer lii is present in an amount ranging from 30 to 50 wt% and the second base layer 112 is present in an amount ranging from 50 to 70 wt% based on the total weight of the multi-layer laminate 11.

The first base layer ill has a refractive index less thanthat of the secondbase layer 112, aridthe refractive index difference between the first and second base layers 111, 112 is preferably greater than 0.03 and less than 0.2, and more preferably ranges from 0.06 to 0.1. The first base layer 111 preferably has a layer thickness that is about 0.07 jim, while the second base layer 112 preferably has a layer thickness that is about 0.15 jim. The layer thickness ratio between the first and second base layers 111, 112 is preferably about 1:2.

The ranges specified above for the structures, the concentrations of the compositions, and the properties of each layer of the sunlight control film of this invention can be appropriately adjusted so as to achieve a desired heat insulation effect and a desired transparency.

The merits of the sunlight control film of this invention will become apparent with reference to the following Examples 1 to 13 and Comparative Examples 1 to6.

Example 1

Preparation of the multi-layer laminate 11 PMMA resin was used to prepare the first base layer 111. A blended resin of 9Owt% of PBT having a viscosity of lPa.a, 7 wt% of coPBT and 3wt% of LLDPE having a melt index of 2 and a density of 0.92 was used to prepare the second base layer 112. The two resins were dried in two different dryers operated at working temperatures of 130 C and 75 C, respectively. After the two dried resins reached a humidity of 40 Ctd, the same were fed into two different extruders and extruded therefrom under working temperatures of 235 C and 240 C and extruding rates of 47kg/hr and 6Okg/hr, respectively.

The extruded resins were delivered to a film-forming system, through which the first and second base layers ill, 112 were formed and were alternately stacked one above the other. The total layer number of the first and second base layers 111, 112 was 100. The stack of the first and second base layers 111, 112 was then delivered to a roller-type laminating machine, through which the same was laminatedundera setting temperature of 30 to 40 C. The laminate 11 thus formed was then deliveredtoabiaxial stretchingmachine, throughwhich the same was stretched 2.5 to 4.5 times of its initial length in the transverse direction orientation (TOO) and 2.5 to 4 times of its initial length in the machine direction orientation (MOO) . The total layer thickness of the stretched laminate 11 thus formed was about 25 jim. The refractive index difference between the first and second base layers ill, 112 thus formed was 0.06.

The weight percentages of the first and second base layers 111, 112 were 35 wt% and 65 wt%, respectively, based on the total weight of the laminate 11 thus formed.

Preparation of the infrared absorbing layer 12 0. 5 wt% of antimony tin oxide powder having a particle size ranging from 100 to l5Onm was blended with 95.5wt% of polycarboriate. The mixture was then applied to the multi-layerlaminatellformedaboveusingacoaterunder a coating speed of 50 m/s, and was subsequently baked under a baking temperature of 65 C so as to form the infrared absorbing layer 12. The layer thickness of the infrared absorbing layer 12 thus formed was 5jim. a

Preparation of the wear resistant layer 13 0.2 wt% of Lanthanum hexaboride was blended with 98.8 wt% of polyester. The mixture was then applied to the infrared absorbing layer 12 formed above using a coater under a coating speed of 50 mIs, and was subsequently baked under a baking temperature ranging from 65 to 70 so as to form the wear resistant layer 13. The layer thickness of the wear resistant layer 13 thus formed was about 1 to 21um.

Preparation of the UV absorbing layer 14 0.5 wt% of benzotriazole was blended with 99.5 wt% of polyacrylate resin. The mixture was then applied to the multi-layer laminate 11 formed above using a coater under a coating speed of 50 m/s, and was subsequently baked under a baking temperature of 65 C so as to form the UV absorbing layer 14. The layer thickness of the UV layer 14 thus formed was about 3im.

A releasing paper was attached to the tJV absorbing layer 14 thus formed for protecting the multi-layer laminate 11 thus formed.

The sunlight control film thus formed was then subjected to infrared and UV absorbing tests using (JV/VIS/NIR (Jasco V-570) spectrophotometer, impact strength test using ANSI Z91.1 standard test method, andtransparencymeasurement. The test results are shown

in Table 1.

Examples 2 and 3

Preparation of the sunlight control film for each of Examples 2 and 3 was similar to that of Example 1, except that the total layer numbers of the laminates 11 for Examples 2 and 3 were 200 and 20, respectively, and that the layer thicknesses of the laminates 11 for Examples 2 and 3 were 35 and 18, respectively. The sunlight control films of Examples 2 and 3 were subjected to the same tests as those of Example 1. The test results are shown in Table 1.

Examples 4 to 7

Preparation of the sunlight control film for each of Examples 4 to 7 was similar to that of Example 1, except that the weight percentages of antimony tin oxide used for Examples 4 to 7 were 0.3, 0.7, 1.0 and 1.1, respectively. The sunlight control films of Examples 4 to 7 were subjected to the same tests as those of Example 1. The test results are shown in Table 1.

Examples 8 to 11

Preparation of the sunlight control film for each of Examples 8 to 11 was similar to that of Example 1, except that the weight percentages of benzotriazole used for Examples 8 to 11 were 0.1, 0.3, 0.7 and 0.9, respectively. The sunlight control films of Examples 8 to 11 were subjected to the same tests as those of Example 1. The test results are shown in Table 1.

Examples 12 and 13

Preparation of the sunlight control film for each of Examples 12 and 13 was similar to that of Example 1, except that the weight percentages of PBT, cQPBT and polyethylene (see Table 1) and the refractive index difference were different from those of Example 1. The sunlight control films of Examples 12 and 13 were subjected to the same tests as those of Example 1. The test results are shown in Table 1.

Table 1 aiple

___ 1 2 3 4 5 6 7 laninate Total 1aer rnirbar 100 200 20 100 100 100 100 Laser thicks, (jin) 25 35 18 25 25 25 25 First: I la.er, (wt%) 35 35 35 35 35 35 35 StiLsselar,(wt%) 65 65 65 65 65 65 65 Seaxd F,wt% 90 90 90 90 90 90 90 base 1ae aDr. Wt% 7 7 7 7 7 7 7 _____ LLL,wt% 3 3 3 3 3 3 3 Ffr. irthcdiffejr 0.06 0.06 0.06 0.06 0.06 0.06 0.06 P20, wt% 0.5 0.5 0.5 0.3 0.7 1.0 1.1 LaBs, wt% 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Biztriazo1e, wt% 0. 5 0.5 0.5 0.5 0.5 0.5 0.5 IR resi.starr, (%) 62-70 70-80 60-62 50-55 72-75 74-80 77-80 rj.i resistarxe, (%) 62-70 70-80 60-62 62-70 62-70 62-70 6270 Iitact strth, (ft/Ib) 55-60 60-70 50-52 55-60 55-60 55-60 55-60 Tanarary, (%) 55-60 47-55 65-70 62-66 52-56 48-50 40-43

Table 1

Ecarp1e _______ 8 9 10 11 12 13 laminate Ibtal 1a.er rixrber 100 100 100 100 100 1.00 La.er thickr, (jn) 25 25 25 25 20 20 First base 1aer, (wt%) 35 35 35 35 35 35 Secaxi base 1aer, (wt%) 65 65 65 65 65 65 Secrrxi r, wt% 90 90 90 90 92 95 base 1aei czEBT. Wt% 7 7 7 7 5 2 _____ U.D,wt% 3 3 3 3 3 3 _____ 0.06 0.06 0.06 0.06 0.1 0.2 tao, wt% 0.5 0.5 0.5 0.5 0.5 0.5 laB6, wt% 0.2 0.2 0.2 0.2 0.2 0.2 zotriazo1e, wt% 0.1 0.3 0.7 0.9 0.5 0.5 JR rsistari, (%) 62-70 62-70 62-70 62-70 58-62 65-68 IJJ ijstarx, (%) 45-55 55-60 68-75 72-79 58-62 65-68 Irract strth, (ft/lb) 55-60 55-60 55-60 55-60 50-55 50-55 Tranaxicy, (%) 65-70 62-66 52-56 48-50 55-58 4850 Comparative Example 1 The sunlight control film of Comparative Example 1 was made from a single layer of polyester (PE) (with a trade name CH284 purchased from NAN YA PLASTICS CORPORATION, Taiwan) having a layer thickness of 20 LLm. The sunlight control films of Comparative Example 1 was subjected to the same tests as those of Example 1. The test results are shown in Table 2.

Comparative Example 2 The sunlight control film of Comparative Example 2 differs Comparative Example 1 in that Comparative Example 2 further includes infrared and IJV absorbing layers and a wear resistant layer which were prepared similar to those of Example 1. The sunlight control film of Comparative Example 2 was subjected to the same tests as those of Example 1. The test results are shown in Table 2.

Comparative Example 3 Preparation of the sunlight control film for Comparative Example 3 was similar to that of Example 1, except that the infrared arid (JV absorbing layers 12, 14 and the wear resistant layer 13 were dispensed with.

The sunlight control film of Comparative Example 3 was subjected to the same tests as those of Example 1. The test results are shown in Table 2.

Comparative Examples 4 and 5 Preparation of the sunlight control film for each of Comparative Examples 4 and 5 was similar to that of Example 1, except that the total layer numbers of the laminates 11 for Comparative Examples 4 and 5 were 10 and 400, respectively, and that the layer thicknesses of the laminates 11 for Comparative Examples 4 and 5 were 15 and 50, respectively. The sunlight control films of Comparative Examples 4 and 5 were subjected to the same tests as those of Example 1. The test results are

shown in Table 2.

Comparative Example 6 Preparation of the sunlight control film for Comparative Example 6 was similar to that of Example 1, except that the weight percentages of PBT, CoPBT and polyethylene (see Table 1) and the refractive index difference were different from those of Example 1. The sunlight control film of Comparative Example 6 was subjected to the same tests as those of Example 1. The test results are shown in Table 2.

Table 2

Ccnparative Sp1e ___ 1 2 3 4 5 6 Laminate Total laser nutber 100 10 400 100 Or Layer thicJcr, (pn) 25 15 50 20 Sin1e First base layer, (wt%) 35 35 35 35 FE layer j} layer, (wt%) 65 65 65 65

FE

Searri r,wt% 90 90 90 87 base iae4r. Wt% 7 7 7 10

_____ ______

Ffra . Jrrcdi.ffererx 0.06 0.06 0.06 0.03 AlO, wt% -0.5 -0.5 0.5 0.5 LaBs, wt% -0.2 -0.2 0.2 0.2 zxtriazo1e, wt% -0.5 -0.5 0.5 0.5 IR resi.staix, (%) 20-30 45-50 45-55 40-50 85-90 40-43 rJ resistar, (%) 2030 45-50 45-55 40-50 85-90 40-43 Inpact strth, (ft/lb) 35-40 40-45 50-55 30-40 75-80 50-55 Trariara-cy, (%) 65-70 55-60 65-70 80-85 35-40 72-75 With the inclusion of the multi-layer laminate 11 in the sunlight control film of this invention, the heat insulation effect of the sunlight control film of this invention can be significantly enhanced as compared to that of the conventional sunlight control film. In particular, both the IR resistance and the UV resistance are greatly enhanced while maintaining the transparency for Examples 1, 3, 5, 9, 10 and 12 as compared to Comparative Example 2.

Claims

CLAIMS: 1. A sunlight control film comprising: a multi-layer laminate

including alternately disposed first and second base layers, the total layer S number of said first and second base layers being at least 20 and less than 400, each of said first and second base layers having a layer thickness ranging from 3800 to 8000 angstroms, the refractive index difference between said first and second base layers being greater than 0.03; and an invisible light absorbing layer unit formed on said multi-layer laminate.
2. The sunlight control film of claim 1, wherein said multi-layer laminate has opposite first and second surfaces, said invisible light absorbing layer unit including an infrared absorbing layer formed on said first surface of said multi-layer laminate, and an UV absorbing layer formed on said second surface of said multi-layer laminate.
3. The sunlight control film of claim 1, wherein the total layer number of said first and second base layers is less than 200.
4. The sunlight control film of claim 1, wherein each of said first base layers is made from an acrylic-based resin material, each of said second base layers being made from a resinous mixture containing a terephthalate-containing polymeric material and polyethylene.
5. The sunlight control film of claim 4, wherein said acrylic-based resin material is made from a polymer polymerized by a monomer selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, and butyl acrylate.
6. The sunlight control film of claim 4, wherein said terephthalate-containing polymeric material is, polybutylene terephthalate.
7. The sunlight control film of claim 6, wherein said resinous mixture further contains a copolymer of polybutylene terephthalate and polyglycol.
8. The sunlight control film of claim 7, wherein said resinous mixture contains 80 to 95 wt% of polybutylene terephthalate, 3 to 15 wt% of said copolymer of polybutylene terephthalate and polyglycol, and 0.5 to wt% of polyethylene.
9. The sunlight control film of claim 8, wherein said resinous mixture contains 85 to 93 wt% of polybutylene terephthalate, 5 to 10 wt% of said copolymer of polybutylene terephthalate and polyglycol, and 1 to 4 wt% of polyethylene.
10. The sunlight control film of claim 2, further comprising a wear resistant layer formed on a selected one of said infrared absorbing layer and said DV absorbing layer.
11. The sunlight control film of claim 10, wherein said wear resistant layer contains a polyester-based resin and Lanthanum hexaboride dispersed in said polyester-based resin.
12. The sunlight control film of claim 11, wherein said Lanthanum hexaboride is present in an amount ranging from 0.1 to 0.3 wt% based on the total weight of said wear resistant layer.
13. The sunlight control film of claim 2, wherein said infrared absorbing layer contains a polycarbonate-based resin and an infrared absorbing agent dispersed in said polycarbonate-based resin and made from a material selected from the group consisting of antimony tin oxide and indium tin oxide.
14. The sunlight control film of claim 13, wherein said infrared absorbing agent is present in an amount ranging from 0.5 to 1.0 wt% based on the total weight of said infrared absorbing layer.
15. The sunlight control film of claim 13, wherein said infrared absorbing layer has a layer thickness ranging from 1 to 10pm.
16. The sunlight control film of claim 2, wherein said UV absorbing layer contains a polyacrylate-based resin and an UV absorbing agent dispersed in said polyacrylate-based resin and made from benzotriazole.
17. The sunlight control film of claim 16, wherein said UV absorbing agent is present in an amount raning from 0.3 to 0.7 wt% based on the total weight of said UV absorbing layer.
18. The sunlight control film of claim 16, wherein said UV absorbing layer has a layer thickness ranging from 1 to 5irn.
19. The sunlight control film of claim 1, wherein said first base layer is present in an amount ranging from to 50 wt% and said second base layer is present in an amount ranging from 50 to 70 wt% based on the total weight of said multi-layer laminate.
20. The sunlight control film of claim 1, wherein said first base layer has a refractive index less than that of said second base layer, the refractive index difference between said first and second base layers being less than 0.2.
21. The sunlight control film of claim 20, wherein the refractive index difference between said first and second base layers ranges from 0.06 to 0.1.
22. The sunlight control film substantially as hereinbefore described with reference to and as illustrated in Fig. 1.