GB1598197A

GB1598197A - Laminated articles

Info

Publication number: GB1598197A
Application number: GB25004/77A
Authority: GB
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1977-06-15
Filing date: 1977-06-15
Publication date: 1981-09-16
Also published as: AU525377B2; AU3678778A; NZ187398A

Description

(54) LAMINATED ARTICLES (71) We, IMPERIAL CHEMICAL INDUS TRIES LIMITED, Imperial Chemical House, Millbank. London SW1P 3JF, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a novel sheet or web material useful in the manufacture of laminated articles having a foamed plastics core.

Foamed plastics are widely used for a variety of purposes. Flexible foams, for instance, are used throughout the furnishings trade, while rigid foams, because of their unusually good thermal insulation properties combined with structural strength, find application in the fabrication of structural components for the building industry.

Unfortunately, a failing of most foamed plastics materials is their combustibility which is mainly due to their organic chemical structure. Further, the physical structure of the foam assists the spread of fire.

The sheet or web material of the present invention when used as a protective skin, improves considerably the fire resistance of these foamed plastics. While the material may be used to improve the fire resistance of any foamed plastics material, it is of particular value in the production of rigid foam laminates used as structural building ele agents especially for industrial buildings.

From the point of view of fire-resistance, plasterboard rigid foam laminates are ideal.

Unfortunately they are heavy and for this reason cannot be used in many modern industrial buildings. Lightweight "fire-resis- tant" foam laminates are commercially available. One type, for instance, comprises a polyisocyanurate foam core covered on both sides with a layer of polythene-coated kraft paper and faced with lacquered aluminium foil. Although rate Class 1 in the British Standard surface spread of fire test, this type of laminate is not as fire-resistant as plasterboard laminates and a flame applied will cause the inner paper and hence the foam core to burn.

In our UK Patent No. 1411148 we describe a rigid foam laminate covered with a skin of glass tissue. Glass tissue, however, does not of itself improve the fire-resistance of foamed plastics to any appreciable extent and if, the kraft paper in the light-weight laminate described above is replaced by glass tissue the overall improvement in fire resistance is marginal. Indeed, because the glass tissue imparts an unattractive wrinkled appearance to the foil the improvement in fire resistance is insufficient to make the less attractive finish of the laminate acceptable to the user.

The sheet or web material of the present invention enables a lightweight structural foam laminate to be produced which has a fire resistance comparable with that of a plasterboard-foam laminate.

According to the present invention we provide a sheet.or web material useful in the manufacture of laminated articles having a foamed plastics core which comprises a composite layer of glass tissue and a moisture-insensitive intumescent material. The invention also includes a process for the manufacture of the sheet or web material, laminated articles having a core of foamed plastics material formed therefrom and a process for the manufacture of such articles.

Glass tissue is commercially available in sheet or web form and comprises randomly disposed glass fibres bound together with a binding agent. There are several methods in use for its manufacture, employing a variety of binding agents. In one method, the fibres are laid down dry on a flat surface and sprayed with a binding agent which is then allowed or caused to cure. In another method the fibres are mixed with a liquid binding agent, the mixture drawn out into sheets (rather as in paper-making) and the binding agent allowed or caused to cure. In general we prefer to use glass tissue made by the latter method. Various binding agents may be used, but polyvinyl alcohol and ureaformaldehyde appear to be most common.

Generally useful is glass tissue made by the latter method and having a density of 60 gm/m2.

By "intumescent material" we mean a material which swells on exposure to fire to produce a fire retardant barrier.

Intumescent materials which previously have been used to form a fire resistant barrier in foam laminates are the sodium silicate water glasses. These materials, however, are water soluble and unsuitable for many applications. Ceiling and wall panels used in building are subjected to water-vapour in the atmosphere and condensation. In many industrial buildings they are subjected to steamy conditions and even though the intumescent material may be shielded behind a moisture impervious film it is virtually impossible to prevent moisture finding its way through joints and affecting the intumescent material. It is important therefore that the intumescent material used in the present invention is substantially unaffected by moisture, i.e. is moisture insensitive.

A moisture insensitive intumescent material which has been found particularly suitable in the present invention is the material obtained by heat-curing the reaction product of a methylol melamine which may be di- to hexa-methylol melamine, and orthophosphoric acid. The melamine may be replaced, at least in part, by another amine, e.g.

dicyandiamide or guanidine, and in place of the orthophosphoric acid another phosphorus compound may be used, e.g. an oxyacid of phosphorus other than orthophosphoric acid, or a precursor therefor or ester thereof.

Melamine is the cyclic trimer formed when cyanamide is heated. The methylol derivatives are obtained by reacting melamine with an appropriate amount of formaldehyde and in fact are intermediates formed in the manufacture of melamine-formaldehyde plastics. The reaction products obtained in the present case are cross-linked methylol melamine-phosphates. Such products are known in the art and typically they are described in UK Patents Nos. 942616, 1058705, 1325806 and 1336063, and in US Patents Nos. 2582961, 3440201 and 3479211.

Preferably the melamine derivative used has more than three methylol groups because the intumescent material formed therefrom exhibits particularly good "water-proof' properties.

Of special value are the intumescent materials made by a process which comprises reacting melamine and at least one aldehyde, or a condensate of melamine and at least one aldehyde, with at least one oxyacid of phosphorus or precursor therefor or ester thereof, for a time sufficient to produce a product which is essentially non-acidic, the proportion of melamine and aldehyde being chosen such that the molar ratio of units derived from melamine: units derived from aldehyde in the product is in the range 1:1.5 to 1:4.5 and the proportion of melamine and oxyacid of phosphorus or precursor therefor or ester thereof being chosen such that the molar ratio of units derived from melamine : phos- phorus in the product is in the range 1:0.4 to 1:1.7.

The intumescent material may be combined with the glass tissue in various ways to form a composite layer. For instance, an aqueous solution of the methylol melamine and phosphorus compound may be applied to the glass tissue by brushing or spraying so that the tissue is impregnated with the solution, and thereafter heating the treated glass tissue, usually at a temperature in the range of 70 to 200"C, to cure the resulting reaction product in situ in the tissue.

The solution may usefully contain various adjuvants including plasticisers, e.g. polyethylene, and catalysts, e.g. zinc nitrate.

Alternatively the intumescent material in ground form, in which the particles may be as large as granulated sugar crystals, may be sprinkled over the glass tissue and adhered to it using a suitable binding agent. Suitable binding agents include those used in producing the glass tissue. Polyvinyl alcohol has been found quite convenient. The binder may be applied before or after the ground intumescent material is sprinkled over the tissue but equally well may be mixed with intumescent material first and the coated intumescent material then applied by any convenient means to the tissue. Satisfactory sheet or web material is obtained using 100 g of intumescent material/m2 of tissue. The glass tissue may be in the form of a facing sheet of, for example, a plastics foam laminate.

As already indicated, the sheet or web material of the present invention is useful in the manufacture of laminated articles having a foamed plastics core.

Thus according to a further aspect of our invention we provide a laminated article having a foamed plastics core covered, at least in part, with a sheet or web material comprising a composite layer of glass tissue and a moisture-insensitive intumescent material.

Foamed plastics materials which may be used in the production of the laminated articles of the invention may be any such materials described in the prior art. Examples of these materials are polyurethane, polyisocyanurate, polyolefin, polystyrene, phenolformaldehyde, epoxy and other poly meric foams. Where the polymeric structure allows. the foams may be rigid, semi-rigid or flexible in nature although the invention finds greatest utility where the foamed plastics are of the rigid type used in constructional elements and where the laminate is made continuously. If desired, the foams may contain conventional fire-retardant additives, for example tris(halogenoalkyl) phosphates or intumescent materials which may be the same as or different from the intumescent material used in the sheet or web material.

Other types of facing material may also be used in part, for instance, those incombustible materials already used in the art which include asbestos cement board, steel, aluminium, tempered glass and perlite board. The sheet or web material covering all or part of the foam core may itself be faced with one or more other materials, and here we would particularly mention aluminium foil.

The extent to which the article is covered with the sheet or web material of the invention will depend on the nature of the article and the purpose for which it is to be used. In general, that part of the article which may become exposed to fire will be covered with a continuous layer of the sheet or web material.

Where the core of foamed plastics material has no other protective facing, it may be desirable for it to be completely enveloped in the sheet or web material. Alternatively, where part of the plastics material is protected by impermeable, incombustible materials such as metal facings, only the unprotected part may require to be covered with the sheet of web material.

The foamed plastics core may be covered with the sheet or web material in any convenient manner. Thus the sheet or web material may be adhered to the foam core using a suitable adhesive or by forming the foam plastics core in situ on the sheet or web material or between two such sheets or webs, bonding of the plastics matrial to the sheet or web material being achieved by the adhesive nature of the uncured foam. Thus the surfaces of a suitable mould may first be lined with the sheet or web material and a foamforming mix of plastics material then introduced into the mould. When the mould has a curved surface, the sheet or web material being flexible can take up the shape of the mould as the foam expands.

Another method is to form the sheet or web material on the laminate in situ by applying the intumescent material to the glass tissue which has already been adhered to the foam core.

Where the laminated article is to be in the form of a panel it may be produced batchwise in a suitably shaped mould as described above or continuously on any laminating machine suitable for the production of foamfilled panels. Such machines are well known in the art and comprise conveying means for continuously advancing flexible or rigid sheet material, usually in a horizontal plane; a spray device or other distributor for depositing a foam mix evenly over the surface of the sheet material, even distribution being achieved either by employing a spreader or by reciprocating the spray device transversely of the sheet material; and, if desired, means for bringing a second sheet material into contact with the foam before. it has set or possibly before or during foaming. When the foam is formed between two facing sheets, the laminate will normally be transported and the foam mix allowed to foam between two parallel conveyors, the conveyors being either maintained at a set distance apart or designed to exert a predetermined pressure on the foam. The foam mix may alternatively be deposited on the upper of two sheets which is inverted when the foam mix has gelled and is then brought into contact with the lower sheet. In manufacturing the laminated articles of the present invention either one or both sheets will be the sheet or web material of the present invention. A second sheet of any other material may be used if desired which is flexible or rigid and may be of an incombustible material such as mentioned above.

Rigid facing materials will normally be in the form of discrete sheets which are fed into the laminating machine in abutment. More conveniently, flexible material is used which is in the form of continuous or semi-continuous sheets fed from rolls. Being flexible, the sheet or web material of the present invention clearly facilitates the continuous production of laminated panels.

The invention is illustrated but not limited by the following Examples in which parts and percentages are by weight unless otherwise stated.

Example I A moisture insensitive intumescent material of particle size 1 5250 microns, prepared by curing at 180or the reaction product of dimethylol melamine and phosphoric acid mixed together in the ratio of 1 :0.5 parts by weight, is mixed with an aqueous polyvinyl alcohol binder to give a spreadable suspension.

The suspension is spread over one side of a glass tissue sheet (density 60 gm/m2) using a palette knife in quantity such that there is 100 gm of the intumescent material/sq.m of tissue and the sheet then allowed to dry.

The dried sheet is suitable for applying to a foamed plastics material as a protective skin.

Example 2 A suspension prepared as described in Example 1 is spread using a palette knife onto an isocyanurate foam laminate foamed between glass tissue sheets (density 60 gm/m2) in quantity such that there is 100 gm of the intumescent material/sq. m of tissue.

The laminate is the allowed to dry.

The laminate has a fire resistance comparable with that of a plasterboard laminate.

WHAT WE CLAIM IS: I. Sheet or web material useful in the manufacture of laminated articles having a foamed plastics core which comprises a composite layer of glass tissue and a moisture-insensitive intumescent material.

2. Material as claimed in claim I in which the intumescent material is obtained by heat-curing the reaction product of a methylol melamine and an oxyacid of phosphorus or precursor therefor or ester thereof.

3. Material as claimed in claim 2 in which the oxyacid of phosphorus is orthophosphoric acid.

4. Material as claimed in claims 2 or 3 in which the melamine is replaced in part by another amine.

5. Material as claimed in claim 4 in which the other amine is dicyandiamide or guanidine.

6. Material as claimed in any one of claims 2 to 5 in which the methylol melamine has more than three methylol groups.

7. Material as claimed in claim 1 in which the intumescent material is made by a process which comprises reacting melamine and at least one aldehyde, or a condensate of melamine and at least one aldehyde, with at least one oxyacid of phosphorus or precursor therefor or ester thereof, for a time sufficient to produce a product which is essentially non-acidic, the proportion of melamine and aldehyde being chosen such that the molar ratio of units derived from melamine: units derived from aldehyde in the product is in the range 1:1.5 to 1:4.5 and the proportion of melamine and oxyacid of phosphorus or precursor therefor or ester thereof being chosen such that the molar ratio of units derived from melamine : phosphorus in the product is in the range 1:0.4 to 1:1.7.

8. Material as claimed in claim 1 substantially as herein described with reference to Example 1.

9. Process for the manufacture of material as claimed in claim 1 in which the intumescent material is formed in situ on the glass tissue.

10. Process for the manufacture of material as claimed in claim 2 in which an aqueous solution of the methylol melamine and phosphorus compound is applied by brushing or spraying to the glass tissue so that the tissue is impregnated with the solution, and thereafter heating the treated glass tissue to cure the resulting reaction product in situ on the tissue.

II. Process as claimed in claim 10 in which the treated glass tissue is heated to a temperature in the range of 70 to 200'C.

12. Process for the manufacture of material as claimed in claim I in which the intumescent material is applied in ground form to the glass tissue and adhered to it using a suitable binding agent.

13. Process as claimed in claim 12 in which the binding agent is a binding agent of the type used in producing glass tissue.

14. Process as claimed in claim 12 in which the binding agent is polyvinyl alcohol.

15. Process as claimed in claim 12 substantially as herein described with reference to Example 1.

16. A laminated article having a foamed plastics core covered, at least in part, with a sheet or web material as claimed in any one of claims 1 to 8.

17. An article as claimed in claim 16 in which the core is a polyurethane or polyisocyanurate foam.

18. An article as claimed in claim 16 as herein described with reference to Examples 1 or 2.

19. Process for the manufacture of an article as claimed in claim 16 which comprises adhering the sheet or web material to the foam core using a suitable adhesive or by forming the foam plastics core in situ on the sheet or web material or between two such sheets or webs, bonding of the plastics material to the sheet or web material being achieved by the adhesive nature of the uncured foam.

20. Process for the manufacture of an article as claimed in claim 16 in which the sheet or web material is formed in situ on the laminate by applying the intumescent material to the glass tissue which has already been adhered to the foam core.

21. Process for the manufacture of an article as claimed in claim 16 substantially as herein described with reference to Examples 1 or 2.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

A suspension prepared as described in Example 1 is spread using a palette knife onto an isocyanurate foam laminate foamed between glass tissue sheets (density 60 gm/m2) in quantity such that there is 100 gm of the intumescent material/sq. m of tissue.

The laminate is the allowed to dry.

The laminate has a fire resistance comparable with that of a plasterboard laminate.

WHAT WE CLAIM IS: I. Sheet or web material useful in the manufacture of laminated articles having a foamed plastics core which comprises a composite layer of glass tissue and a moisture-insensitive intumescent material.
2. Material as claimed in claim I in which the intumescent material is obtained by heat-curing the reaction product of a methylol melamine and an oxyacid of phosphorus or precursor therefor or ester thereof.
3. Material as claimed in claim 2 in which the oxyacid of phosphorus is orthophosphoric acid.
4. Material as claimed in claims 2 or 3 in which the melamine is replaced in part by another amine.
5. Material as claimed in claim 4 in which the other amine is dicyandiamide or guanidine.
6. Material as claimed in any one of claims 2 to 5 in which the methylol melamine has more than three methylol groups.
7. Material as claimed in claim 1 in which the intumescent material is made by a process which comprises reacting melamine and at least one aldehyde, or a condensate of melamine and at least one aldehyde, with at least one oxyacid of phosphorus or precursor therefor or ester thereof, for a time sufficient to produce a product which is essentially non-acidic, the proportion of melamine and aldehyde being chosen such that the molar ratio of units derived from melamine: units derived from aldehyde in the product is in the range 1:1.5 to 1:4.5 and the proportion of melamine and oxyacid of phosphorus or precursor therefor or ester thereof being chosen such that the molar ratio of units derived from melamine : phosphorus in the product is in the range 1:0.4 to 1:1.7.
8. Material as claimed in claim 1 substantially as herein described with reference to Example 1.
9. Process for the manufacture of material as claimed in claim 1 in which the intumescent material is formed in situ on the glass tissue.
10. Process for the manufacture of material as claimed in claim 2 in which an aqueous solution of the methylol melamine and phosphorus compound is applied by brushing or spraying to the glass tissue so that the tissue is impregnated with the solution, and thereafter heating the treated glass tissue to cure the resulting reaction product in situ on the tissue.
II. Process as claimed in claim 10 in which the treated glass tissue is heated to a temperature in the range of 70 to 200'C.
12. Process for the manufacture of material as claimed in claim I in which the intumescent material is applied in ground form to the glass tissue and adhered to it using a suitable binding agent.
13. Process as claimed in claim 12 in which the binding agent is a binding agent of the type used in producing glass tissue.
14. Process as claimed in claim 12 in which the binding agent is polyvinyl alcohol.
15. Process as claimed in claim 12 substantially as herein described with reference to Example 1.
16. A laminated article having a foamed plastics core covered, at least in part, with a sheet or web material as claimed in any one of claims 1 to 8.
17. An article as claimed in claim 16 in which the core is a polyurethane or polyisocyanurate foam.
18. An article as claimed in claim 16 as herein described with reference to Examples 1 or 2.
19. Process for the manufacture of an article as claimed in claim 16 which comprises adhering the sheet or web material to the foam core using a suitable adhesive or by forming the foam plastics core in situ on the sheet or web material or between two such sheets or webs, bonding of the plastics material to the sheet or web material being achieved by the adhesive nature of the uncured foam.
20. Process for the manufacture of an article as claimed in claim 16 in which the sheet or web material is formed in situ on the laminate by applying the intumescent material to the glass tissue which has already been adhered to the foam core.
21. Process for the manufacture of an article as claimed in claim 16 substantially as herein described with reference to Examples 1 or 2.