AU706149B2 - Improvements in moulding of plastics articles - Google Patents

Description

-la- This invention relates to improvements in the moulding of :"plastics articles and more particularly moulding by the rotational moulding process.

V6 When moulding plastics articles (such as in a rotational moulding process) it is often desired that the article be applied with some labelling, graphics or the like.

Traditionally this has involved a post-moulding operation of applying a label, graphic or the like to the surface of the moulded article. A problem which arises, however, is unsuccessful or partially incomplete attachment of the label, graphics or the like due to glue not adhering to the product.

In addition to the label or graphics failing to achieve the aesthetic appeal desired (due to its "glued on" appearance) there is the cost associated with a post-moulding operation.

It is known from US 4519972 to provide labelling, graphics or the like to a rotationally moulded article as part of the rotational moulding process. This is achieved by using a transfer which is applied to the surface of the mould prior to the moulding operation being carried out. Such a process, however, is relatively time-consuming, involves a degree of expertise and can be expensive. For example, the application of the transfer to the wall of the rotational mould can be time-consuming and achieving the desired high quality end result can require a high level of expertise and experience to correctly apply the transfer. Also, the actual moulding process may need to be modified to achieve the end result and this can lead to additional costs and longer moulding times.

too o SUMMARY OF THE INVENTION The object of the present invention is to provide a process for applying a label, graphic or the like to the surface of a moulded article during a moulding process.

Broadly in one form of the invention there is provided a process for applying a label, graphic or the like to the surface of a moulded article during a moulding process including printing or otherwise applying graphics, wording and the like to a synthetic paper, adhering the printed side of the synthetic paper to the surface of the mould, moulding the article and removing the moulded article from the mould with the synthetic paper in place thereon, the bond between the paper and the moulded article being greater than residual adherence of the paper to the surface of the mould.

According to the preferred form of the invention there is provided a process for applying a label, graphic or the like to the surface of an article during moulding of the article by a rotational moulding process. However, it is envisaged that the process can be applied to moulding of articles using other procedures such as injection moulding or blow moulding.

o S o o DESCRIPTION OF THE PREFERRED EMBODIMENTS .:.ooi According to the present invention the graphics, written *5*S o° S* word, etc are printed onto a synthetic printing sheet or paper by normal printing methods such as screen printing, photocopying or offset printing. Preferably screen printing is employed because of the greater/denser body of ink used.

S. S The synthetic paper is of a type which has a variety of known end uses including providing labels for plants or use in outdoor situations. The synthetic paper is thus waterproof and able to withstand the effects of normal environmental conditions such as sunlight and rain as well as being able to withstand cleaning processes. It can also withstand typical temperatures existing during a moulding process.

In the preferred form of the invention the synthetic paper is of the type sold under the trade mark TESLIN (Trade Mark).

TESLIN is a single layer, highly filled microporous film which is printable and durable. The material is a polyolefin which contains approximately 60 weight non-abrasive filler.

This structure is approximately 65 volume percent air. The porous, uncoated nature of TESLIN permits inks, adhesives, coatings and laminating films to penetrate into the structure to form anchor points with the substrate.

the preferred form the synthetic paper has a thickness which is as thin as possible and preferably in the range of about 0.1mm to 0.25mm preferably about 0.15mm. In particular *.ool to avoid buckling which can arise with paper thicker than is required for the end purpose the thinnest possible paper which can withstand the effects of the moulding procedure is employed.

Once the paper has been printed it is applied by a contact adhesive printed side to the wall surface of the mould in the position in which the graphic, label or the like is to be located on the moulded article. Prior to the paper being adhered to the wall of a mould release agents in the area in which the label/graphics is to be applied must be cleaned off. A solvent can be used or the area polished with a suitable abrasive.

In the preferred form of the invention the adhesive is applied by spraying to both the label/graphics and the mould surface and allowed to become tacky before the label/graphics is located in place. In the preferred form of the invention the adhesive is brand 77-N of 3M. Other equivalent adhesives can, however, be used.

In an alternative arrangement a proprietary brand touch sensitive glue can be applied to the label and then covered by a silicon backing or release paper. This pre-gluing of the label is advantageous as the labels can be prepared ready for immediate use by simply peeling the backing/release paper from the label/graphic and then applying the label/graphic to the surface of the mould as previously described. Such touch sensitive glues are commonly used for self-adhesive labels and an example of a suitable proprietary brand is GRIPIT and preferably 0086 type.

**The touch sensitive glue can be applied to the label in a known manner using, say, a laminating machine which uses a transfer roller to coat the glue to the surface of the label followed by immediate application of the backing/release paper to cover the adhesive. For complex shape graphics/labels, it has been found to be preferable to carry out finishing work, ie die cutting, after the application of the touch sensitive glue and backing/release paper.

Upon the label/graphics being applied to the wall of the mould air bubbles are removed, eg by using a spatula or t j J1 6 squeegee type device, following which any glue residue around the label/graphics is removed.

In a preferred form of the invention an overgloss (sealant) is applied to the printed surface of the label/graphic prior to the application of glue. This application of the overgloss layer can preferably take place as a final operation of the printing of the label especially when a screen printing process is used. Alternatively, the overgloss layer can be applied once the label has been :00 finished but prior to the glue being applied to the label.

The use of this overgloss or sealant layer can provide for more effective cleaning of the label surface after the moulding operation has taken place and reduces the adverse affect which a cleaning solvent can have on the ink.

According to a preferred form of the invention, the label/graphic is preheated in a heating oven prior to being applied to the surface of the mould. This heating of the label/graphic results in pre-shrinking of the label so as to avoid or significantly reduce shrinkage of the label/graphic during the moulding operation. While this is preferably carried out for large dimension labels, pre-shrinking of the label by heating is advantageous for all sized labels/graphics as it reduces and indeed generally prevents any tearing or cracking of the label/graphic as a consequence of shrinkage during the moulding procedure. The temperature to which the label is heated can be between a temperature where shrinking occurs and degradation of the label but preferably it has been found that heating to about 150 0 C is sufficient.

The article is then moulded in accordance with normal rotational moulding procedures. Upon the article being "'"removed from the mould the bonding between the label/graphics S..o and the moulded article is greater than the strength or oeooo residual strength of the adhesive holding the label/graphics to the wall of the mould. As a consequence the 0.00 *ooS* "label/graphics release intact from the mould wall to thereby .i form an integral part of the moulded article. Any residue adhesive is then cleaned from the wall of the mould prior to 15 the next moulding operation taking place.

S*

0 The process according to the present invention thus provides a simple, effective and economical means of applying labels, graphics and the like to a plastics article during the actual moulding operation. Depending on the manner in which the graphics/wordage is applied to the synthetic paper a high quality label/graphics integrally formed with the moulded article can be achieved and which cannot be removed without physically degrading the product, for example, by grinding.

mmmmmmmmood 8 THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:i. A process for applying a label, graphic or the like to the surface of a moulded article during a moulding process including printing or otherwise applying graphics, wording and the like to a synthetic paper, adhering the printed side of the synthetic paper to the "surface of the mould, moulding the article and removing the moulded article from the mould with the synthetic 96 paper in place thereon, the bond between the paper and the moulded article being greater than residual adherence of the paper to the surface of the mould.

0o 2. The process according to claim 1 wherein the moulding 15 process is a rotational moulding process.

3. The process according to claim 1 wherein the moulding process is an injection moulding process.

4. The process according to claim 1 wherein the moulding process is a blow moulding process.

The process according to any one of claims 1 to 4 wherein the synthetic paper is a printable and durable single layer highly filled microporous film.

Claims (12)

1. 6. The process according to claim 5 wherein the synthetic paper is a material comprising a polyolefin containing approximately 60 weight percent non-abrasive filler and the structure is approximately 65 volume percent air.
2. 7. The process according to any one of claims 1 to 6 wherein the synthetic paper has a thickness which is as thin as possible preferably in the range of about 0.1mm to about 0.25mm.
3. 8. The process according to claim 7 wherein the thickness is about 0.15mm.
4. 9. The process according to any one of claims 1 to 7 15 wherein the synthetic paper is adhered to the mould using a contact adhesive applied to the printed side of the paper and the area of wall surface of the mould where the graphic, label or the like is to be positioned. The process according to claim 9 wherein the adhesive is applied by spraying.
5. 11. The process according to claim 9 or 10 wherein the adhesive is brand 77-N produced by 3M Company.
6. 12. The process according to any one of claims 1 to 11 where the printing is carried out in a screen printing process.
7. 13. The process according to any one of claims 1 to 12 wherein a touch sensitive adhesive is applied to the printed side of the synthetic paper, said touch sensitive glue being used to adhere the synthetic paper to the surface of the mould.
8. 14. The process according to claim 13 wherein a backing/release paper applied to the touch sensitive glue and removed prior to application of the synthetic paper to the surface of the mould.
9. 15. The process according to any one of claims 1 to 14 including the step of pre-shrinking of the label, graphic or the like by heating.
10. 16. The process according to claim 15 wherein the label, graphic of the like is heated to a temperature of about 150 0 C.
11. 17. The process according to any one of claims 1 to 16 wherein an overgloss or sealant layer is applied to the synthetic paper after the printing/graphics have been applied thereto. 11
12. 18. A process for applying a label, graphic or the like to the surface of a moulded article substantially as herein described. Dated this 21 day of February 1997 STEPHEN HENRY CRAWSHAW and 0* ELIZABETH MARIA CRAWSHAW trading in partnership as S STALLION PLASTICS Patent Attorneys for the Applicant PETER MAXWELL ASSOCIATES 0 s 0S Ji i ABSTRACT A process for applying a label, graphic or the like to the surface of a moulded article during a moulding process. Printing, graphics and the like are applied to a synthetic paper and the printed side of the synthetic paper is adhered to the surface of the mould. The article is then moulded in the mould and upon removal of the moulded article the 000 "0 label/graphic is set in place in the moulded article due to 6 0 10 the bond between the paper and the moulded article being .0 greater than residual adherence of the paper to the surface of the mould. 0946 0 *0 0 0