GB2134444A - Heat rejecting window - Google Patents

Heat rejecting window Download PDF

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Publication number
GB2134444A
GB2134444A GB08302697A GB8302697A GB2134444A GB 2134444 A GB2134444 A GB 2134444A GB 08302697 A GB08302697 A GB 08302697A GB 8302697 A GB8302697 A GB 8302697A GB 2134444 A GB2134444 A GB 2134444A
Authority
GB
United Kingdom
Prior art keywords
glass
oxide
solar heat
vehicle window
coating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB08302697A
Other versions
GB8302697D0 (en
Inventor
Charles Raymond Bamford
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pilkington Group Ltd
Original Assignee
Pilkington Brothers Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pilkington Brothers Ltd filed Critical Pilkington Brothers Ltd
Priority to GB08302697A priority Critical patent/GB2134444A/en
Publication of GB8302697D0 publication Critical patent/GB8302697D0/en
Publication of GB2134444A publication Critical patent/GB2134444A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/1055—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer
    • B32B17/10761—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the resin layer, i.e. interlayer containing vinyl acetal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/06—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of natural rubber or synthetic rubber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/10009—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets
    • B32B17/10036—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing characterized by the number, the constitution or treatment of glass sheets comprising two outer glass sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B32B17/10005—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin laminated safety glass or glazing
    • B32B17/10165—Functional features of the laminated safety glass or glazing
    • B32B17/10174—Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2264/00—Composition or properties of particles which form a particulate layer or are present as additives
    • B32B2264/10—Inorganic particles
    • B32B2264/102—Oxide or hydroxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric
    • B32B2307/204—Di-electric
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B32B2307/306—Resistant to heat
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2605/00—Vehicles
    • B32B2605/006—Transparent parts other than made from inorganic glass, e.g. polycarbonate glazings

Abstract

A laminated vehicle window for rejecting solar heat has at least two plies of glass (1, 3) or transparent plastics material with a refractive index of 1.4 to 1.6 for visible light. One of the pies (1) has a coating (4) comprising a silver layer 8 to 18mm thick sandwiched between two layers of dielectric material each 20 to 60mm thick. The pies (1, 3) are laminated together with an interlayer (2) and the coating (4) contacting the interlayer (2). The dielectric material may be an oxide of titanium, tin, bismuth, zinc or indium. <IMAGE>

Description

SPECIFICATION Heat rejecting window The invention relates to vehicle windows, and in particular to laminated vehicle windows with good solar heat rejecting properties.
It is known that the passenger compartments of vehicles, especially motor cars, tend to become overheated on hot days because excessive solar heat enters through the vehicle windows. The problem has been alleviated by making the vehicle windows from glass containing one or more heat absorbing metal oxides, for example iron oxide, or a combination of iron oxide with cobalt oxide and selenium oxide. However, the incorporation of such metal oxides not only reduces the heat transmitted by the glass, but also reduces the light transmission.
It will be appreciated that it is commonly important in vehicle windows, especially windscreens, to maintain a high level of light transmission, so that the vehicle driver retains a high level of visibility. Thus, because of the need to maintain visibility at acceptable levels, only a limited amount of heat absorbing metal oxide can be incorporated in the glass. The most efficient glasses in this respect i.e. with good solar heat absorption and high visible lighttransmission contain a small proportion, typically about 0.5%, of iron oxide; 5 mm thick panes of such glass, suitable for use as windscreens, typically have a light transmission of about 77% and a total solar heat transmission of about 66%.The expression "total solar heat transmission" is used in this specification and appended claims to designate the total of (1) the solar heat directly transmitted and (2) solar heat initially absorbed and subsequently transmitted in a direction away from the source of solar heat.
It would be beneficial if vehicle windows could be produced either with an improved combination of light transmission properties and solar heat transmission properties, or with similar properties but without the need to use special glass containing added metal oxides.
It has previously been proposed, in UK patent specification 1,307,642, to produce a glass article having a three layer coating comprising a layer of silver 20-30 mm thick sandwiched between two anti-reflection layers of non-light-absorbing dielectric material for use in an electrically heated window.
The coating has good electrical conductivity and is said to have a visible light reflection of less than 10 per cent and excellent refection of heat or infra red radiation. When coated glasses in accordance with the specification are used to produce laminates, the resulting laminates are said to have light transmissions of 71% and 73%.
It has now been found that when a ply of glass coated with a silver layer sandwiched between two anti-reflection layers of dielectric material is laminated to a second ply of glass or transparent plastics with a refractive index similar to that of the glass, with the coating between plies, the reflection of the coating in the near infra red is, surprisingly, increased. In consequence, useful heat rejecting laminated windows can be produced using three layer coatings comprising a layer of silver, significantly thinner than the silver layers used in accordance with the teaching of UK patent specification 1,307,642, sandwiched between two anti-reflection layers of dielectric material.Because the silver layer used is thinner than taught in UK patent specification 1,307,642, the visible light transmission is higher so that, when laminate is used as a vehicle window, visibility from inside the vehicle is improved.
According to the present invention, there is provided a solar heat rejecting laminated vehicle window having a light transmission of more than 75% and a total solar heat transmission of less than 70%, said laminate being composed of at least two plies, each independently of glass or a transparent plastics material with a reflective index of 1.4 to 1.6 for visible light, one of the said two plies bearing a coating comprising a layer of silver 8 to 18 mm thick sandwiched between two layers of dielectric material each 20 to 60 nm thick with the coating between the said two plies.
The coating comprises a layer of silver 8 - 18 nm thick sandwiched between the anti-reflection layers of dielectric material each 20 to 60 nm thick. The dielectric material used should have a refractive index of at least 1.5, and preferably of about 2 or more. Examples of suitable dielectric materials include metal oxides, for example titanium oxide, tin oxide, bismuth oxide, zinc oxide and indium oxide (optionally doped with tin oxide) and metal sulphides, for example zinc sulphide. in order to maximise the visible light transmission of the coating, it is preferred to use a dielectric material that does not absorb light in the visible regions of the spectrum.
The two layers of dielectric material serve as anti-reflection layers in the visible region of the spectrum, that is, they serve to reduce the light reflection and thereby increase the lighttransmis- sion of the coating. The optimum thickness of each of the layers of dielectric material will depend on the particular properties required in the product, especially the light transmission and total solar heat transmission. In general, for maximum light transmission, the optical thickness of the dielectric layer should be in the range 60 - 100 nm where optical thickness = physical thickness x refractive index of dielectric.
On the other hand, for minimum solar heat transmission, the solar heat reflection should be at a maximum. In general, reducing the thickness of the dielectric layers in the sandwich below the optimum value for maximum visible light transmission shifts the maximum anti-reflection effect to shorter wavelength, i.e. increases the reflection at longer wavelengh, paricularlywavelengths in the near infra-red. Thus, if a small decrease in the visible light transmission overthat obtained when using the optimum thicknesses required for maximum light transmission can be tolerated, a significant increase in the solar heat reflection (with a consequent decrease in the total solar heat transmission) may be achieved by reducing the thicknesses of the dielectric layers.
The individual layers of the coating may be deposited in known manner, for example by deposition processes preformed under vacuum, for exam- ple vacuum evaporation and cathode sputtering processes. It is usually convenient to apply the coating to a glass ply.
For most applications, vehicle windows in accordance with the invention may conveniently comprise two plies of glass laminated together with an intermediate ply or interlayer of polyvinylbutyal.
When used for motor vehicle windscreens, each glass ply present will usually have a thickness in the range 1.5 to 3mm.
If desired, one of the plies may itself be of a glass containing a proportion of heat absorbing metal oxide to increase the solar heat absorption of the window still further, provided that its use does not result in a reduction of the light transmission of the window below the specified 75% level.
Example A pane of clear float glass 2.5 mm thick was coated by cathode sputtering under a vacuum with a first layer of tin oxide 40 nm thick, a second layer of silver 10 nm thick and a third layer of tin oxide, similar to the first layer, 40 nm thick so that the silver layer was sandwiched between the metal oxide layers.
The coated glass had, when illuminated from the non-coated side, a light transmission of 84%, a light reflection of 10%, a solar heat reflection of 17%, a solar heat absorption of 15% and a total solar heat transmission of 73%.
The coated pane was laminated to an equally dimensioned uncoated pane of 2.5 mm thick clear float glass with a 0.75 mm thick interlayer of polyvinylbutyral in a conventional manner. The coated pane was arranged with the coated surface towards the polyvinylbutyral interlayer. The resulting laminated window, comprising 2 plies of glass and a central ply of polyvinylbutyral, is suitable for use as a flat vehicle windscreen. It is shown in section in the accompanying drawing. In the drawing, 1 is the coated ply of flat glass, 2 the polyviny Ibutyral interlayer and 3 the uncoated ply of float glass. The coating 4 is on the side of ply 1 against thE polyvinylbutyral interlayer. In use, the window is preferably glazed with the coated ply towards the sun.When illuminated in this manner, i.e. with the coated ply towards the source of illumination, the laminate had the following optical properties: light transmission 80% lightrelection 10% solar heat refection 21% solar heat absorption 20% total solar heat transmission 65% It will be noted that the light reflection of the laminated product, at 10%, is equal to the light reflection of the single coated pane. In contrast, the solar heat reflection of the laminated product, at 21%, is surprisingly higher than the solar heat reflection of the single coated pane (17%). The light transmission of the laminate at 80% is, as expected, less than the light transmission of the single coated pane (84%). However, whilst the light transmission of the laminate is 4% less than the light transmission of the single coated pane, the total solar heat transmission of the laminate is some 8% lower than the total solar heat transmission of the single coated pane.
If desired, one of the panes of clear float glass, preferably the uncoated pane, may be replaced by a pane of glass containing a proportion of iron oxide, for example about 0.5%, as a heat absorbing constituent.

Claims (6)

1. A solar heat rejecting laminated vehicle window having a light transmission of more than 75% and a total solar heat transmission of less than 70%, said laminate being composed of at least two plies, each independently of glass or a transparent plastic material with a reflective index of 1.4 to 1.6 for visible light, one of the said two plies bearing a coating comprising a layer of silver8 to 18 nm thick sandwiched between two layers of dielectric material each 20 to 60 nm thick with the coating between the said two piles.
2. A laminated vehicle window according to claim 1 wherein each of the two layers of dielectric material in the coating is a layer of titanium oxide, tin oxide, bismuth oxide, zinc oxide, or indium oxide optionally doped with tin oxide.
3. A laminated vehicle window according to claim 1 or claim 2 comprising two plies of glass laminated together with an interlayer of polyviny Ibutyral.
4. A laminated vehicle window according to claim 3 being a vehicle windscreen in which each glass ply has a thickness in the range 1.5 to 3 mm.
5. A laminated vehicle window according to any of the preceding claims wherein one of the plies is a pane of glass containing a proportion of iron oxide as a heat absorbing constituent.
6. A laminated vehicle window substantially as herebefore described in the Example and illustrated in the accompanying drawing.
GB08302697A 1983-02-01 1983-02-01 Heat rejecting window Withdrawn GB2134444A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08302697A GB2134444A (en) 1983-02-01 1983-02-01 Heat rejecting window

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08302697A GB2134444A (en) 1983-02-01 1983-02-01 Heat rejecting window

Publications (2)

Publication Number Publication Date
GB8302697D0 GB8302697D0 (en) 1983-03-02
GB2134444A true GB2134444A (en) 1984-08-15

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ID=10537275

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08302697A Withdrawn GB2134444A (en) 1983-02-01 1983-02-01 Heat rejecting window

Country Status (1)

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GB (1) GB2134444A (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4687687A (en) * 1985-03-28 1987-08-18 Glaverbel Transparent glazing panels
WO1988001230A1 (en) * 1986-08-20 1988-02-25 Libbey-Owens-Ford Co. Solar control glass assembly and method of making same
US5332888A (en) * 1986-08-20 1994-07-26 Libbey-Owens-Ford Co. Sputtered multi-layer color compatible solar control coating
ES2119681A1 (en) * 1995-04-27 1998-10-01 Glaverbel Coated substrate having high luminous transmission, low solar factor and neutral aspect in reflection.
US9102123B2 (en) 2006-02-14 2015-08-11 Pilkington Automotive Limited Glazing
US11959272B1 (en) 2020-11-25 2024-04-16 Herbert L. deNourie Building construction

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1307642A (en) * 1969-04-07 1973-02-21 Asahi Glass Co Ltd Electrically conductive glass articles
GB1317368A (en) * 1970-06-13 1973-05-16 Delog Detag Flachglas Ag Heat-reflecting window pane
GB1513826A (en) * 1974-07-26 1978-06-14 Saint Gobain Coated transparent sheets
GB2031498A (en) * 1978-09-27 1980-04-23 Teijin Ltd Multi-pane window structure

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1307642A (en) * 1969-04-07 1973-02-21 Asahi Glass Co Ltd Electrically conductive glass articles
GB1317368A (en) * 1970-06-13 1973-05-16 Delog Detag Flachglas Ag Heat-reflecting window pane
GB1513826A (en) * 1974-07-26 1978-06-14 Saint Gobain Coated transparent sheets
GB2031498A (en) * 1978-09-27 1980-04-23 Teijin Ltd Multi-pane window structure

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4687687A (en) * 1985-03-28 1987-08-18 Glaverbel Transparent glazing panels
WO1988001230A1 (en) * 1986-08-20 1988-02-25 Libbey-Owens-Ford Co. Solar control glass assembly and method of making same
US4943484A (en) * 1986-08-20 1990-07-24 Libbey-Owens-Ford Co. Solar control glass assembly and method of making same
US5332888A (en) * 1986-08-20 1994-07-26 Libbey-Owens-Ford Co. Sputtered multi-layer color compatible solar control coating
ES2119681A1 (en) * 1995-04-27 1998-10-01 Glaverbel Coated substrate having high luminous transmission, low solar factor and neutral aspect in reflection.
US9102123B2 (en) 2006-02-14 2015-08-11 Pilkington Automotive Limited Glazing
US11959272B1 (en) 2020-11-25 2024-04-16 Herbert L. deNourie Building construction

Also Published As

Publication number Publication date
GB8302697D0 (en) 1983-03-02

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