GB2194197A - A method of forming a screen - Google Patents

A method of forming a screen Download PDF

Info

Publication number
GB2194197A
GB2194197A GB08619168A GB8619168A GB2194197A GB 2194197 A GB2194197 A GB 2194197A GB 08619168 A GB08619168 A GB 08619168A GB 8619168 A GB8619168 A GB 8619168A GB 2194197 A GB2194197 A GB 2194197A
Authority
GB
United Kingdom
Prior art keywords
sheets
screen
enclosure
transparent material
combination
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Withdrawn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
GB08619168A
Other versions
GB8619168D0 (en
Inventor
Graham Stafford Bright
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.)
RFI Shielding Ltd
Original Assignee
RFI Shielding 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 RFI Shielding Ltd filed Critical RFI Shielding Ltd
Priority to GB08619168A priority Critical patent/GB2194197A/en
Publication of GB8619168D0 publication Critical patent/GB8619168D0/en
Publication of GB2194197A publication Critical patent/GB2194197A/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Withdrawn legal-status Critical Current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
    • B32B17/10165—Functional features of the laminated safety glass or glazing
    • B32B17/10376—Laminated safety glass or glazing containing metal wires
    • 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
    • B32B17/1055—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
    • 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
    • B32B17/10807—Making laminated safety glass or glazing; Apparatus therefor
    • B32B17/10816—Making laminated safety glass or glazing; Apparatus therefor by pressing
    • B32B17/10825—Isostatic pressing, i.e. using non rigid pressure-exerting members against rigid parts
    • B32B17/10834—Isostatic pressing, i.e. using non rigid pressure-exerting members against rigid parts using a fluid
    • B32B17/10844—Isostatic pressing, i.e. using non rigid pressure-exerting members against rigid parts using a fluid using a membrane between the layered product and the fluid
    • B32B17/10853—Isostatic pressing, i.e. using non rigid pressure-exerting members against rigid parts using a fluid using a membrane between the layered product and the fluid the membrane being bag-shaped
    • 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
    • B32B2305/00—Condition, form or state of the layers or laminate
    • B32B2305/38—Meshes, lattices or nets
    • 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
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/42—Polarizing, birefringent, filtering

Landscapes

  • Joining Of Glass To Other Materials (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)

Abstract

A method for forming a screen, for a VDU for example, which comprises first and second sheets 1, 2 of transparent material and at least one intermediate bonding layer 3 disposed between the sheets 1, 2 is disclosed which includes the steps of placing the sheets 1, 2 and intermediate layer 3 in a substantially air impermeable flexible enclosure, evacuating and sealing the enclosure and applying a combination of pressure and temperature to the enclosure so as to bond the sheets 1, 2 and intermediate layer 3 together. <IMAGE>

Description

SPECIFICATION A method of forming a screen This invention relates to a method of forming a screen.
Screens, for example windscreens or screens for visual display units (VDU's), usually include two sheets of transparent material, eg glass, between which is sandwiched a layer of plastics material to give strength and prevent the screen from shattering. The glass and plastics components are bonded together to form the screen by application of a combination of high temperature and pressure in an autoclave.
It is essential, during forming, that the elements of the screen are held in place relative to one another, so that they may be bonded in a chosen orientation relative to each other.
Several methods have been proposed to accomplish this. In a first method, a vacuum is applied at the edge of the screen components through a rubber sealing ring attached to the screen edge. The ring is connected to a vacuum pump which draws air from the gap between the glass sheets and plastics material, to hold the components in place. It is a disadvanatage of this method, however, that the ring needs to be of a specific size for a given size of screen. The ring is also prone to leakage and requires the constant attachment of a vacuum source, or valve, to maintain the screen components in place. Also, as the vacuum is only applied at the edge of the screen this can result in uneven holding pressure.
In an alternative method, the screen elements are placed on an aluminium sheet; a nylon film is placed over the screen components and mastic is applied round the edges of the components, between the film and aluminium sheet, to form an enclosure, which is then evacuated. This method also suffers from the disadvantage that leakage occurs around the mastic and it is impossible to maintain a seal without constant evacuation, to compensate for the leakage. Also, this method is difficult to use with curved screens, due to the different shape of the screen components and aluminium sheet. Also, once evacuated, the sheet and screen assembly requires careful handling.
In a further method, the components of the screen are clamped together between a pair of press-heat plates and are bonded by application of temperature and pressure between the plates. However, this method suffers the disadvantage that high pressures needs to be applied to the components to cause them to bond together, resulting in undue stress in the finished article. This is particularly a problem if the glass plates differ in shape from the press plates, due to surface irregularities, for example.
It is an object of the invention to provide a method of forming a screen which enables the components of the screen to be held in place relative to one another in a simple and reliable manner.
According to the invention there is provided a method of forming a screen which comprises first and second sheets of transparent material and an intermediate bonding layer disposed between the sheets comprising the steps of placing the sheets and intermediate layer in a substantially air impermeable flexible enclosure, evacuating and sealing the enclosure and applying a combination of pressure and temperature to the enclosure so as to bond the sheets and intermediate layer together.
An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a curved screen, showing the various components thereof Figure 2 is a sectional view taken across the line 2'-2' of Figure 1 Figures 3 and 4 show stages in the method of the present invention.
With reference to Figure 1, the components of a screen, in this case a VDU screen are shown. The screen comprises first and second curved sheets of glass, between which is disposed a radio frequency shield 5, formed of fine woven or knitted copper mesh, for example. First and second sheets of plastics material 3,4 (preferably polyvinyl butyral (PVB) are disposed between the shield 5 and sheets 1,2 and the plastics sheets act as a intermediate bonding layer.
These components are placed prior to bonding in a flexible air impermeable plastics enclosure 6 which is preferably formed from a transparent nylon/ethelene polypropylene (EPP) bag (the nylon providing strength and the polypropylene flexibility and heat sealing ) (see Fig. 3). In order to hold the components together within the bag, the bag and component assembly is placed in a standard vacuum packing machine, in which the bag 6 is evacuated, for example to-1,000 millibars vacuum and then heat sealed by melting the bag at seal line 8 (see Fig. 4).
During evacuation, the bag 6 conforms to the shape (including irregularities) of the glass sheets and provides a flexible clamp for holding the components of the screen together.
The whole assembly can then be removed from the vacuum packing machine without fear of the components of the screen moving relative to one another and allowing convenient transportation of the whole assembly to the next stage of the forming process. The assembly can also be examined through the bag 6 to determine any necessary inspection criteria mis-alignment of glass etc. Any defects can be corrected by opening the bag 6 thereby releasing the vacuum and then realign ing component parts of the assembly. The assembly is then placed back in the bag 6, and the vacuum re-applied and the bag 6 re sealed.
Following evacuation and sealing, the bag 6 is placed in an oven for preliminary heating at 125"C for approximately 30 minutes. This stage is needed in order to allow the PVB, which has a translucent appearance, to become transparent and to form the initial bond.
Inspection is also possible at this stage through the bag although rectification is not possible on bonded areas ofthe assembly. It does however stop the unnecessary autoclaving of reject assemblies. Following this, the assembly is placed in an autoclave, where heat and pressure are applied to bond the components together. The autoclave operates on a purge cycle for 10 minutes, followed by a pressure phase for 30 minutes, by application of steam or dry air at 138"C, 35 to 70 PSI. This is followed by a cool down phase for 40 minutes.
By suitable control of the autoclave process, the separate preliminary heating stage may be omitted.
As the enclosure 6 has been evacuated, the components of the screen are already compressed under approximately one atmosphere of pressure. This allows the pressure in the autoclave to be reduced compared to conventional pressures for windscreen formation for example, which would be of the order of 200 PSI.
Whilst the embodiment of the invention has been described with regard to a VDU screen, it is equally applicable for any other type of screen with or without an RFI shield, for example a windscreen.
Also, whilst the embodiment has been described with reference to a glass and PVB component screen, it is equally applicable to screens formed from polycarbonate or acrylic.
For polycarbonate, the interlayer is preferably formed from polyurethane, with PVB being used for acrylic, the autoclave temperature/pressures for acrylic being 70 PSI 90-95 C dry air and for polycarbonate 70 PSI 120"C dry air.

Claims (1)

1. A method of forming a screen which comprises first and second sheets of transparent material and an intermediate bonding layer disposed between the sheets comprising the steps of: placing the sheets and intermediate layer in a substantially air impermeable flexible enclosure, evacuating and sealing the enclosure; and applying a combination of pressure and temperature to the enclosure so to bond the sheets and intermediate layer together
2. A method as claimed in claim 1 further comprising the step of pre-heating the sealed enclosure prior to applying the combination of pressure and temperature.
3. A method as claimed in claim 1 or claim 2 wherein the flexible enclosure is evacuated to a vacuum greater than - 1,000 millibars.
4. A method as claimed in any one of the preceding claims wherein the combination of pressure and temperature is applied in a autoclave.
6. A method as claimed in any one of the preceding claims wherein the flexible enclosure comprises a bag formed from plastics material.
7. A method as claimed in claim 6 wherein the plastics bag is formed from a combination of nylon and ethelene polypropylene.
8. A method as claimed in claim 6 or claim 7 wherein the plastics bag is sealed by heat sealing.
9. A method as claimed in any one of the preceding claims wherein the enclosure is formed from transparent material.
10. A method as claimed in any one of the preceding claims wherein the sheets of transparent material are formed from glass and the intermediate bonding layer comprises polyvinyl butyral.
11. A method as claimed in any one of claims 1 to 9 wherein the sheets of transparent material are formed from a polycarbonate and the intermediate bonding layer comprises polyurethane.
12. A method as claimed in any one of claims 1 to 9 wherein the sheets of transparent material are formed from acrylic and the intermediate bonding layer comprises polyvinyl butyral.
13. A method of forming a screen substantially as hereinbefore described with reference to the accompanying drawings.
GB08619168A 1986-08-06 1986-08-06 A method of forming a screen Withdrawn GB2194197A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08619168A GB2194197A (en) 1986-08-06 1986-08-06 A method of forming a screen

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08619168A GB2194197A (en) 1986-08-06 1986-08-06 A method of forming a screen

Publications (2)

Publication Number Publication Date
GB8619168D0 GB8619168D0 (en) 1986-09-17
GB2194197A true GB2194197A (en) 1988-03-02

Family

ID=10602301

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08619168A Withdrawn GB2194197A (en) 1986-08-06 1986-08-06 A method of forming a screen

Country Status (1)

Country Link
GB (1) GB2194197A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0340924A2 (en) * 1988-05-06 1989-11-08 Rfi Shielding Limited Method of forming a screen
DE102010054055A1 (en) * 2010-12-10 2012-06-14 Giesecke & Devrient Gmbh Production of a card-shaped data carrier

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1306502A (en) * 1969-01-24 1973-02-14 Triplex Safety Glass Co Processing of laminated transparent panels
GB1382186A (en) * 1972-12-01 1975-01-29 Ppg Industries Inc Laminates
GB1431070A (en) * 1973-07-17 1976-04-07 Ici Ltd Hot melt adhesive composition
GB1483937A (en) * 1973-09-14 1977-08-24 Ppg Industries Inc Impact-resistant glass-polyesterurethane laminates
GB1528774A (en) * 1975-10-28 1978-10-18 Vesnitskaya G Method of manufacturing a laminated material based on glass-like transparent plastics material
GB2116111A (en) * 1982-02-25 1983-09-21 Ppg Industries Inc Forming shaped laminates

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1306502A (en) * 1969-01-24 1973-02-14 Triplex Safety Glass Co Processing of laminated transparent panels
GB1382186A (en) * 1972-12-01 1975-01-29 Ppg Industries Inc Laminates
GB1431070A (en) * 1973-07-17 1976-04-07 Ici Ltd Hot melt adhesive composition
GB1483937A (en) * 1973-09-14 1977-08-24 Ppg Industries Inc Impact-resistant glass-polyesterurethane laminates
GB1528774A (en) * 1975-10-28 1978-10-18 Vesnitskaya G Method of manufacturing a laminated material based on glass-like transparent plastics material
GB2116111A (en) * 1982-02-25 1983-09-21 Ppg Industries Inc Forming shaped laminates

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
WO A1 85/02371 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0340924A2 (en) * 1988-05-06 1989-11-08 Rfi Shielding Limited Method of forming a screen
EP0340924A3 (en) * 1988-05-06 1991-10-09 Rfi Shielding Limited Method of forming a screen
DE102010054055A1 (en) * 2010-12-10 2012-06-14 Giesecke & Devrient Gmbh Production of a card-shaped data carrier

Also Published As

Publication number Publication date
GB8619168D0 (en) 1986-09-17

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WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)