GB2516238A

GB2516238A - Improvements in or relating to cladding of structures

Info

Publication number: GB2516238A
Application number: GB1312618.0A
Authority: GB
Inventors: David G Davis
Original assignee: FOCUS DGI Ltd; JUDE JONES Ltd
Current assignee: FOCUS DGI Ltd; JUDE JONES Ltd
Priority date: 2013-07-15
Filing date: 2013-07-15
Publication date: 2015-01-21
Also published as: GB201312618D0

Abstract

The structure is clad with a sheet of plastic wherein the sheet is adhered to the structure by between 0.5 to 1.5 kg per square metre of adhesive. The adhesive is at least two component ambient temperature curable adhesive with a viscosity that allows spreading within five minutes of mixing the components. The adhesive has a working time of up to 60 minutes. The plastic sheet may be a rigid or semi rigid polyvinyl chloride (PVC). The adhesive may be polyurethane adhesive. The structure may be a drywall finish constructed of sheet building material. Also claimed is a trowel where grooves in the spreading edge of the trowel are spaced apart by a distance of at least 2cm but preferably between 2 and 4cm. The grooves may have a width of 1cm and a depth of up to 1cm.

Description

IMPROVEMENTS IN OR RELATING TO CLADDING OF STRUCTURES

The present invention relates to the bonding of cladding materials to structures and in particular to building structures such as walls. Hygienic cladding is frequently required on walls in environments such as hospitals, clinics, food processing establishments, pharmaceutical manufacture and research and other situations where a sterile environment is required. The invention also relates to a spreading trowel that may be used in such bonding activities.

Typically cladding is provided manually onto walls by coating the reverse side of a sheet of the cladding material with an adhesive and then pressing the coated side of the cladding material against the surface of the wall so that it adheres thereto. The wall itself may be of any material such as wood or masonry such as brick or plaster such as plasterboard. The invention is particularly useful in the provision of cladding to a drywall finish constructed of sheet building material. The adhesive must be such that it can be used in the application cycle. This requires that it can be spread on the cladding material, will not cure until the cladding is located against the wall and will not sag under gravity during the curing process particularly in situations where the cladding is being provided on a vertical structure.

The adhesives used are typically two component adhesive systems which cure at ambient temperature over a period of time following the mixing of the components. In a typical cycle the components are mixed in a container to provide the required amount of adhesive for the application of a cladding sheet, the adhesive is then coated onto the cladding sheet employing a tooth edge spreading trowel and the coated sheet then pressed uniformly against the surface of the structure which spreads the adhesive between the sheet of cladding and the structure. The process is then repeated with subsequent sheets of cladding material until the final clad area has been produced. The working time of the adhesive is the time following the mixing of the ingredients in which the adhesive remains spreadable. The cure time is the time required for the adhesive to form a strong bond which is longer than the working time.

The working time for the adhesive will therefore start upon mixing of the adhesive components and progress through application to the cladding to provide the appropriate viscosity for spreading. Thereafter the adhesive should set to adhere the cladding to the structure. The process suffers from the disadvantage that large amounts of adhesive are required due to the design of the spreading trowel which typically has a toothed edge with gaps between the teeth of about 6 mms which provide strips of the adhesive which are then flattened out across the interface between the cladding and the wall as the cladding is pressed against the wall. Typically in order to clad a wall it has been traditional to use between 1.5 and 3 kg per sqm of two-component adhesive which is expensive.

We have now found that satisfactory adhesion between a cladding panel and a wall can be achieved by the use of a smaller quantity of adhesive. We have found that this may be achieved by using an adhesive having a particular viscosity profile including reduced viscosity in the working time during spreading at room temperature and during the cure cycle of the adhesive together with a novel form of spreading trowel.

The invention therefore provides a structure clad with a sheet of plastic wherein from 0.5 to 1.0 kilograms per square metre of a two or more component ambient temperature curable adhesive having a viscosity to enable ready spreading of the adhesive within five minutes after mixing of the components and having an working time of up to 60 minutes is employed to bond the cladding to the structure.

It is preferred that the working time is from 10 to 60 minutes.

The sheet of plastic is preferably a sheet of rigid or semi-rigid polyvinyl chloride.

We have found that when an adhesive whose viscosity during the working time is reduced by about 10% compared to the standard adhesive is used to bond the cladding to the wall a satisfactory bond between the cladding and the wall can be achieved employing no more than 1.5 kg of adhesive per square metre of wall surface.

We have also found that if the adhesive is applied to a wall using a new design of spreading trowel in which the spacing distance between the spreading grooves is increased to at least 2 cms the lower amount of adhesive may be readily applied within the normal manual application cycle to obtain a uniform coating of the adhesive which will cure during the normal manual application cycle to provide satisfactory adhesion between the cladding and the wall.

Accordingly in a further embodiment the invention provides a toothed spreading trowel wherein the grooves in the spreading edge of the trowel are spaced apart by a distance of at least 2 cms. The grooves are preferably spaced apart by a distance of between 2 and 4 cms and the grooves themselves preferably have a width up to 1 cm and a depth of up to 1 cm.

The invention may be used for the cladding of any structure in particular walls. The walls may be made from a variety of materials include wood of various sorts, plasterboard, plastics perhaps as foamed material and metals such as steel or aluminium and masonry.

The cladding material will be chosen according to the use to which the article is to be put.

Rigid or semi-rigid polyvinyl chloride (PVC) is a preferred cladding material for use in hygienic environments and the PVC is preferably free of plasticiser. Other cladding materials that may be used include poly(meth)acrylates, polyolefines such as polypropylene and high density polyethylene, polyamides and polycarbonates.

The adhesive should be such that it will cure sufficiently to be self-supporting in place within a particular time such as in no more than 30 minutes although longer time will be required for complete cure. A two part polyurethane adhesive has been found to be particularly suitable.

Such an adhesive will start to cure upon mixing of the two parts.

The present invention is illustrated but in no way limited by reference to the accompanying Figures in which Figure 1 shows a conventional trowel used for the application of adhesive.

Figure 2 shows a trowel of the present invention with the increased spacing of the grooves.

The invention is also illustrated by the following Examples in which an adhesive system of the present invention was compared with a standard adhesive system for the bonding of PVC cladding to substrates.

The amount of force needed to break the adhesive bond (by removing the cladding sheets from the substrate) was measured on samples using the two different adhesive systems.

The following test procedure was employed.

1. Cladding Samples were prepared, one set of small samples at 330mm x 820mm, and a second set of large samples at 665 x 820mm.

2. The sheet material was cleaned.

3. The substrate of 18mm standard medium density fibreboard was wiped over with standard cleaner to remove any dust or grease.

4. The two-part adhesive was mixed and the time of mixing recorded.

5. The adhesive was applied to the pieces of test material: 2.5 kg/sqm of the standard adhesive system was used on half of the small samples, and half the large samples and 1 kglsqm of the adhesive system of this invention was used on the remaining small samples, and the remaining large samples.

6. The samples of cladding coated with the adhesive were then placed onto the standard medium density fibreboard substrate, with the edge of the sheet overhanging the substrate slightly. The sheets were then rolled evenly using a panel roller to spread the adhesive and achieve an even and consistent bond. All the panels were bonded to the substrate within 20 minutes of mixing the adhesive.

7. The bonded system was then left for 72 hours to enable full cure of the adhesive.

8. The samples were then removed from the substrate using a force gauge fixed to the overhanging edge of the sheet and the force was recorded as the sheet started to peel, and the force needed to complete the removal of the sheet from the substrate was also recorded.

9. This was repeated on all the samples, and the recordings of each test set were combined to obtain average readings for each adhesive system.

10. The test was then repeated on a plasterboard substrate and recordings taken in the same way. A successful bond was maintained, so that the force recorded is the force required for the paper plasterboard facing to delaminate from the plasterboard core, not the delamination of the cladding from the substrate.

Figure 3 is a curve showing the force required to remove the cladding using the adhesive of the present invention and Figure 4 shows the force required employing the standard adhesive. The figures show that bonds of acceptable strength can be obtained using significantly less of the adhesive of the present invention.

Claims

CLAIMS1. A structure clad with a sheet of plastic wherein from 0.5 to 1.5 kilograms per square metre of a two or more component ambient temperature curable adhesive having a viscosity to enable ready spreading of the adhesive within five minutes after mixing of the components and having an working time of up to 60 minutes is employed to bond the cladding to the structure.
2. A structure according to Claim 1 in which the plastic is rigid or semi-rigid polyvinyl chloride.
3. A structure according to Claim 1 or Claim 2 in which the adhesive is a two part polyurethane adhesive.
4. A structure according to any of Claims 1-3 in which the structure is a drywall finish constructed of sheet building material.
5. A toothed spreading trowel wherein the grooves in the spreading edge of the trowel are spaced apart by a distance of at least 2 cms.
6. A spreading trowel according to Claim 5 in which the grooves are spaced apart by a distance of between 2 and 4 cms.
7. A spreading trowel according to Claim 5 or Claim 6 wherein the grooves have a width tol cmanda depth of up tol cm.