AU620440B2

AU620440B2 - Method for the manufacture of laminated elements

Info

Publication number: AU620440B2
Application number: AU41300/89A
Authority: AU
Inventors: Anthony M. Bedford; Thomas R. Wilshaw
Original assignee: Cotton John Ltd
Current assignee: JOHN COTTON (COLNE) Ltd
Priority date: 1989-03-23
Filing date: 1989-09-12
Publication date: 1992-02-20
Anticipated expiration: 2009-09-12
Also published as: GB2231308B; JPH02261623A; GB2231308A; GB8906845D0; AU4130089A

Description

6010 w

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

620440 Int. Class Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority oiE~Related Art: Applicant(s): John Cotton (Colne) Limited Spring Gardens Mill, Colne, Lancashire, BB8 8EL, UNITED KINGDOM Address for Service is: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Complete Specification for the invention entitled: METHOD FOR THE MANUFACTURE OF LAMINATED ELEMENTS Our Ref 146997 POF Code: 1519/107547 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1- 1 6006 ir! ;i I I 1. 1 11 I I 46- b e Status.. v CoC4IV IfG r U'% St atus... METHOD FOR THE MANUFACTURE OF LAMINATED ELEMENTS This invention relates to a method for the preparation of L I t l reinforcing web for laminated elements, Laminated elements comprising one or more reinforcing and/or decorative layers are used for example as roof lining panels (so-called "headliners"), door panels, automobile engine compartment insulation panels and general decorative panels in the automobile and aircraft t industries. In some applications, such as for headliners, the laminated elements include a cellular layer.

Such panels may be manufacture by a large number of hitherto a proposed processes. For example, GB-B-2096653 describes a process @000 for the preparation of lightweight, insulating, flexible, rigid or semirigid elements which comprises impregnating a flexible open-celled porous material with a solution of an isocyanate compound, reacting the o°°0 isocyanate with water to form a urea or biuret derivative and crossoo 0 linking the isocyanate. The impregnation step may be followed or o 00 accompanied by the deposition of a fibrous material on the porous o°ooo material so that the isocyanate acts as a bonding and embedding agent 00 4 for the fibres. The surface of the porous material may also be coated with continuous coating material, the isocyanate once again acting as a 0t bonding agent.

It has been proposed to prepare laminated panels containing a thermoforming cellular material e.g. of polyurethane foam, as a core material, by pre-heating the thermoforming material to a temperature Sat which the material can be moulded, and then placing the preheated material into a mould. Before placing the core material in the mould, the mould surfaces are provided with any desired reinforcing and/or decorative layers for the final produce, and these layers are coated with an appropriate adhesive for bonding to the core material. The mould is also pre-heated to a temperature which is sufficient to cure the adhesive, but which is less than the thermoforming temperature of la _i I I -A -2the foam core. Closure of the mould then serves to bond the reinforcing and/or decorative layers to the core material and to form the panels into the desired final shape.

It has also been proposed in our European Patent Application No.

0 266 224 to provide a process for the preparation of laminated elements containing at least one reinforcing web layer and a thermoformable cellular core material, which avoids preheating the material before a moulding step. Adhesive for bonding the layers together to form an intermediate laminated element is sprayed onto the aooe reinforcing layer prior to contact with the core material thus avoiding the need to impregnate the foam core. The intermediate laminated element is then placed in a heated mould which serves both to deform the thermoformable cellular core material and to cure the adhesive.

We now provide an improved method of manufacturing reinforcing webs for use in laminated elements and an improved method of manufacturing laminated elements which is economic and safe and which requires simple processing. In particular, we have now found it convenient to pre-treat a reinforcing web by applying, e.g. by impregnation or coating, an adhesive before it is used in a process for manufacturing a laminated element.

Thus i=fs aat the invention provides a method for preparing a laminated element comprising a thermoformable cellular core acres\ v e material and at least one 4 pe-treated reinforcing web,which comprises SC placing the thermoformable cellular core material on said reinforcing web to form an intermediate laminated product, and placing the intermediate laminated product without substantial preheating in a heated mould to deform the materials to a desired final shape and to 1 t1L0 tvm Q(\vk-S\Vvtcure the adhesive, wherein said reinforcing web has been pre-treated by applying e-a adhesive to the web in a separate preceding adhesive According to a preferred embid' method of the invention is used to aminated element having a plurality of r g cr% n nrt!i. tvo or uiu c i,.f ui~ ng u. A 1 3I -I

-VI

application operation which includes applying the adhesive to the reinforcing web in liquid form, and drying the adhesive after application to the web but before the thermoformable cellular core material is placed on the web.

According to a preferred embodiment, the method of the invention is used to prepare a laminated element having a plurality of reinforcing layers, conveniently two or more reinforcing layers. A coeo o o ao t Q4F 2a- 1-

I

-3preferred element of the invention is provided with a backing or scrim layer and a top layer, which according to the desired application may have a decorative surface. Thus, in a most preferred embodiment, the method is used to prepare a laminated element having a scrim or backing layer, a first reinforcing layer, the cellular core layer, a second reinforcing layer and a top face layer. In this embodiment, the scrim conveniently comprises a non-woven or woven fabric e.g. of polyester, viscose, glass fibre or combinations thereof, with a weight of, for .R o example, 10-100 g.m 2 preferably 20-60 g.m- 2 The first reinforcing layer conveniently comprises an organic or inorganic material selected from carbon, boron, polyamide, polyester, viscose, ceramic, cotton, metal fibres and combinations thereof, and preferably a glass fibre mat, generally of non-woven material with a weight of 50-400 g.m 2 preferably 100 to 200 g.m 2 which is laid over the scrim. An especially preferred material for the reinforcing layer comprises a non-woven chopped glass strand mat with a weight of about 150 g.m 2 This material is of generally open texture so that in the pre-treatment 0o, operation the adhesive passes through the mat. The scrim may be preo°°o coated on what will become the rear surface of the laminated product with for example a thin film of polyethylene. This coating additionally 0000 provides a pleasing finish and increases the strength of the final product. If desired the reinforcement layer may be impregnated with suitable resin before being applied in the method of the invention.

So In the pre-treatment operation, the reinforcing web is prepared for subsequent use in the method by application of an adhesive, preferably a thermosetting resin adhesive which conveniently includes thermally reactive and moisture curing resin systems such as t polyurethanes, phenol formaldehydes, polyesters, acrylics, vinyls, epoxys, polyester sulphanes and a variety of mixtures and blends and physical forms thereof including liquids, thin films and powders.

The particular selection of adhesive type depends on a number of factors. Thus, in general, the process and the properties of the moulded laminate may be influenced by the adhesive in the following respects: ti ~f~il _I i -4- 0000 oo 0 o o 0 0 oo~o 0000 00 00 o o 0 0 o 0 0o 0 o o 00 o o 0 00 0000 0000 0 0 0 00 0 0 00 0 0 0 0oo o 0o 00 0 o0 0 0 00 000000 o o The adhesive may provide an element of matrix support for the reinforcement which would affect the strength and stiffness of the laminate.

High temperature curing characteristics will usually be desired which preserve detail, such as surface detail, in the moulded laminate.

The adhesive will usually be chosen such that bonding of all of the reinforcing layers, both together and to the cellular foam core is achieved, (when more than one reinforcing layer is desired).

The adhesive also affects high temperature rigidity and therefore influences the de-moulding characteristics of the laminate, it being desirable to achieve stable dimensionally accurate moulding even upon immediate release from the mould dies.

Where appropriate the adhesive should exhibit high temperature thermal stability to resist degradation under extremes of environmental conditions depending on the service specifications and conditions of the relevant final application or industry.

The adhesives may conveniently be categorised into two types:adhesives with short ambient life-times before curing, typified by polyurethane adhesives which may be applied wet to the reinforcing layer and moulded before they have dried; and adhesives with longer ambient life-times which may be applied to the reinforcing layer either using wet or dry techniques but which can sustain a long shelf life prior to use in the method for the preparation of a laminated element, in which the adhesive is reactivated by the application of heat.

Preferred adhesives for use according to the invention are phenol formaldehyde resins. The phenol formaldehyde resin is preferably applied in liquid form, to coat or impregnate the reinforcing mat at any time prior to moulding.

In some cases an adhesive preferably may include a water-based or organic solvent-based carrier.

Using a pre-treatment technique in accordance with the invention, the adhesive on the reinforcing layer can be allowed to dry and the layer subsequently re-rolled into a long length of reinforcing material which may then be used in a later laminating and moulding operation for preparation of the laminated element.

By drying the web, it is possible to prepare a product which may, if necessary and/or desired, be stored for an indefinite period prior to subsequent use in the method of the invention. This may be highly convenient for a processor and may have economic advantages.

A dip process is preferably used to coat or impregnate the reinforcing layer to achieve the required dry pick up weight of adhesive, controlled preferably within the range of 10 to 100 gms per sq. metre. The dry pick up weight of resin is usually dependent upon the density of the web and the final properties required of the laminate.

The viscosity of the resin solution also determines the pick up weight.

A drying oven is preferably used in the reinforcement web preparation to provide a drying means for drying and/or removing solvent after application of the adhesive, thereby leaving the CO4t reinforcement web with a dry coating. A flexible reinforcing web is thereby not tacky and, as indicated above, is suitable for re-rolling into long continuous lengths which can then be stored for subsequent application in the moulding process, in which the laminated element may be formed.

0 In the subsequent method for preparing a laminated element, the G 1necessary laminating layers of material are conveniently fed o a simultaneously from pay-off reel stands such that they can be fed continously to one or more moulding presses. The moulding process requires no pre-heating of any of the laminate layers and all materials can be passed directly into the moulding press without an further a preparation.

When the reinforcing layer has been prepared it is subsequently used in the process for forming a laminated element, in which the thermoformable cellular core material may be applied. When the laminated product is intended for use where sound-attenuating properties may be desired, such as for use as decorative panels in automotive or aircraft applications, it is preferred to use an opencelled core material. Closed-cell materials may be preferred in other applications. The cellular material may be rigid, semi-rigid or flexible depending on the desired final application. In general, the ~!1 i -6thermoformable cellular material will be of polyurethane, although other cellular materials, such as thermoplastic foam materials, may be used if desired. For automotive applications, such as for headliners, it is preferred to use a polyurethane thermoformable cellular material which provides good mouldability and product definition.

The core material is preferably pre-cut to a size and thickness appropriate to the desired final product before being placed on the pretreated reinforcing layer. The core material may conveniently be cut from slabstock or from roll material. The cores may also be preformed into a desired shape. For use in headliners, the core material generally has a thickness in the range of from 2 to 30 mm.

When the core material has been placed on a first reinforcing layer, if desired, a second and subsequent reinforcing layers may be °,oo laid over the core material. The subsequent reinforcing layer will generally be identical to the first reinforcing layer, but this is not essential.

In a final stage for preparing the intermediate laminated element, a a o o a top layer, which if desired may be a decorative layer, may be applied °o to the second reinforcing layer. The top layer may be any material .soo serving to provide the desired appearance of the final product such as 0 O for example woven, non-woven and thermoplastic film materials.

When the top layer has been applied, the intermediate laminated product is passed, without substantial pre-heating, to the moulding operation. The mould dies used correspond to the desired shape of the 'final product and are pre-heated to a temperature to effect deformation of the intermediate laminated product to the desired shape and to cause curing of the adhesive layers. We have found that a Smoulding temperature in the range of from 100 to 2000 is convenient and about 180 0 C is preferred. If, for example, a heat-sensitive decorative layer is used, it is possible to employ a mould in which the mould part in contact with the decorative layer is at a somewhat lower temperature. The laminated product is generally held in the mould for about 30 to 180 seconds, preferably 60 to 90 seconds, depending upon -7the moulding properties of the materials and the cure characteristics of the adhesive. The edges of the mould dies are generally such as to nip the top and bottom layers of the laminated element together; this serves to aid trimming of the final product and to prevent subsequent delamination. Other edge-types such as cropped, return, front or reversed edges may be formed on the final product by conventional techniques.

After the moulding step, the laminated product is generally allowed to cool in a cooled former in order to maintain the desired shape and dimensions of the product. If desired, the former may be provided with suction holes to suck air through the product and thus 'promote cooling.

In a modification of the above described method, which modification is intended to be within the scope of the present invention, it is possible to prepare laminated elements as described above but omitting the thermoformable cellular core material. In a preferred 0¢ embodiment of this modified method, a laminated element is prepared having a scrim or backing layer, one or more reinforcing layers, and optionally a top layer which may if desired have a decorative surface.

In a most preferred embodiment of this modification there is provided a 000 oo0 method for the preparation of laminated elements having a backing or 0 00 044 scrim layer, a first and a second reinforcing layer, and a top layer. The scrim, reinforcing and top layers may be laminated together by a S' process which is directly analogous to the method described above with the sole exception that the cellular core material is omitted. A laminated element according to a particular embodiment may thus S- comprise a non-woven bonded fabric backing layer, e.g. of .0o °t polyester/viscose with a weight of 25 to 35 g.m-2; a first reinforcing layer comprising a non-woven bonded fabric, e.g. a glass fibre mat with polyester/viscose having a weight of about 150 g.m2; a similar second reinforcing layer; and a top layer with a weight of 80 to 150 g.m 2 The reinforcing layers will have been pre-treated as described above i.e. by prior application of adhesive. As indicated above, these layers may be

I-

8 combined to give an intermediate product which is placed in a mould tool (with matched male and female dies) under similar conditions as described above.

As indicated above the laminated elements produced in accordance with the invention are particularly suitable for use in the automotive and aircraft industries, for example as decorative panels such as headliners for cars, vans and trucks. Laminated products modified as above described to omit the cellular core layer may be particularly useful as insulation panels for automobile engine compartments. In some applications, such as in the aircraft industry, the elements should be formed using non-flammable or selfextinguishing materials, or by treating the materials with fire-retardant chemicals. Examples of non-flammable cellular core materials include phenolformaldehyde, polyether sulphone and polyether imide foams, which may be used with non-flammable resin adhesives such as phenolformaldehyde resins. Polyvinyl fluoride is an example of a nonflammable material which may be used as a decorative layer.

Embodiments of the invention will be hereinafter described by way of non-limiting example with reference to the accompanying drawings in which:- 4 Figure 1 shows a schematic side view of the apparatus for use according to an embodiment of the invention in the production of reinforcing layers; and Figure 2 shows a schematic side view of apparatus for use according to an embodiment of the invention in the production of automobile headliners.

SIn the apparatus shown in Figure 1, reinforcing material, si preferably glass fibre matting, is drawn from roller 1 and passed through dancer arm controlled pay-off stand 2. The dancer arm 2 feeds the reinforcing web into a dip coating bath 3 which contains the adhesive solution 3A, preferably phenol formaldehyde resin. The coated web then passes through rubber coated nip rollers 4 which squeeze out of the web any excess liquid resin.

4 t t U12~rC 4 44 41 4 4 a 4 -9- The web then passes through a heated oven 5 in which excess water or solvent fluids are dried off to leave a dry pre-coated reinforcing web. The web may then be conveniently re-rolled 6 ready for warehouse storage for use when necessary.

In the apparatus shown in Figure 2 scrim material is drawn from roller 7 and passed through nip rollers 9 together with first reinforcing material drawn from roller 8 which has been pre-treated, e.g. using the apparatus shown in Figure 1 described above. The combined web thereby formed is then passed to an automatic sheet feed station where a cellular core layer 11 is placed on the web. Of course, it is possible to locate the cellular core layer 11 on the web manually if desired. The cellular core layer 11 is prepared from slab stock material by apparatus (not shown) for cutting sheets of desired size and thickness.

A second pre-treated layer of material is drawn from roller 12 and overlayed onto the cellular core layer on the web. Decorative face material is drawn from roller 13 and applied to the substrate to form an intermediate laminate product 14. The intermediate laminate product is then passed to a single or multi moulding press operation. A gripper conveyor 15, commonly known as a stenter type conveyor holds the product ready for presentation to the moulding press using clips 16 on the side of the conveyor. The intermediate laminate product 14 is thereby carried to the moulding station 17 and placed between the dies 18,19 of a mechanical or hydraulically operated double-acting press.

The dies are electrically heated to a temperature sufficient to mould the thermoformable cellular core and to cure the adhesive. If the decorative layer on the intermediate product is heat sensitive, the temperature of the upper die 18 may be lower than that of the lower die 19.

When the dies 18,19 of the press open, the laminate product may be carried to a mechanical or hydraulically operated trimming press which may be fitted with cutting dies 21,22 which cut the moulded laminated to the desired dimensions.

n! :j i i i i 10 The product may optionally be carried to a cooling station where the product is held in another double-acting press. The dies of the press conveniently being cooled with cold water.

The final laminate product 23 may be carried forward to a declamping station where the clips 16 are released and the final product removed.

The method allows the use of economic materials and a simplified moulding process line. In addition there are significant health risk benefits from the removal of the necessity for spraying adhesive onto the reinforcing layers during the moulding process, in particular the removal of the need to spray isocyanate type adhesives.

While the embodiment described above is provided with two reinforcing layers, a core and scrim and decorative layers i.e. to form a laminate having five layers, it will be appreciated that laminated products having more and less layers are within the scope of the invention.

It will be appreciated that the preparation of modified products as described above, i.e. those omitting the cellular core layer, may be effected on similar apparatus as shown in the figures with the omission of the sheet feed station €445 4 4-4 4

Claims

1. A method for preparing a laminated element comprising a thermoformable cellular core material and at least one adhesive treated reinforcing web which comprises placing the thermoformable cellular core material on said reinforcing web to form an intermediate laminated product, and placing the intermediate laminaled product without substantial preheating in a heated mculd to de-orm the materials to a desired final shape and to cure the adhesive, wherein said reinforcing web has been pre-treated with the adhesive by applying the adhesive to the web in a separate preceding adhesive application operation which includes applying the adhesive to the reinforcing web in liquid form, and drying the adhesive after application to the web but before the thermoformable cellular core material is placed on the web.

2. A method according to claim 1 wherein the adhesive is a thermosetting resin.

S3. A method according to claim 2 wherein the :20 adhesive is a polyurethane, phenol formaldehyde, polyester, acrylic, vinyl, epoxy, polyester sulphane, or a mixture thereof.

4. A method according to claim 3 wherein the adhesive is phenol formaldehyde resin. -25

5. A method according to any preceding claim wherein the web is coated or impregnated with the adhesive.

6. A method according to any one of the preceding o claims wherein the adhesive is applied to the reinforcing web by dipping the web into the adhesive.

7. A method according to any one of claims 1 to 6 wherein the adhesive is dried by means of a drying oven.

8. A method according to any one of claims 1 to 7 wherein the adhesive includes a water based or organic solvent-based carrier.

9. A method according to claim 8 wherein the water or organic solvent is removed from the adhesive after application to the web but before the thermoformable cellular core material is placed on the web.

A method according to claim 9 wherein the A CC L a. 11 IC~ i 1 i' 6006 I i water or organic solvent is removed by means of a drying oven.

11. A method according to any preceding claim wherein the laminated element comprises a scrim layer, a first reinforcing layer, a cellular core layer, a second reinforcing layer and a top decorative web layer.

12. A method according to claim 11 wherein the first and second reinforcing layers are identical.

13. A method according to any preceding claim wherein the core material is precut to a size and thickness appropriate to the desired final product before being placed on the web.

14. A method for preparing a laminated element substantially as herein described with reference to the accompanying drawings. DATED: 5 December 1991 PHILLIPS ORMONDE FITZPATRICK .o2"o30 Attorneys for: JOHN COTTON (COLNE) LIMITED oooa o o o 00 00010 o e I oo 006 0 1259b VF -12- i