IE921277A1

IE921277A1 - Forming mouldings with simulated wood grain surfaces

Info

Publication number: IE921277A1
Application number: IE127792A
Authority: IE
Inventors: Aldino Abertelli
Original assignee: A Foam Co Ltd
Priority date: 1991-04-22
Filing date: 1992-04-22
Publication date: 1992-11-04
Also published as: AU1573592A; ZA922915B; MX9201862A; WO1992018341A1; GB9108569D0

Abstract

Synthetic resin moldings such as panels and doors having an improved simulated wood grain finish are obtained by coating a part of all of the mold surface with at least one colourant, having a colour which is different from the colour of the resin when cured, prior to effecting contact between the mold surface and the surface of a moldable body of curable synthetic resin, the colourant being transferred to the surface of the curable resin when contact is effected and retained on said surface when the molding is parted from the mold.

Description

This invention relates to the production of synthetic resin moldings having a simulated wood grain surface.

It is known that products such as panels, doors, door frames, window frames, artificial wooden beams, etc., can be produced with a molded synthetic resin surface to which a simulated wood grain finish has been applied by effecting contact, usually with pressure, between a surface of a fluid body of curable synthetic resin, e.g. polyester resin, and a mold surface designed to impress the simulated wood grain effect on said resin surface. The curable resin is then normally maintained in contact with the mold surface until it has been cured to the state where the fine detail of the impressed finish is not lost or significantly undesirably impaired when the molding is parted from the mold.

The desired surface of the mold may be obtained, for example, by forming the mold against a suitable wooden surface. The effect may be enhanced by causing the wooden surface to swell, e.g. by soaking it, prior to its use as the former.

The wood grain-like finish on the synthetic resin molding may be further improved by suitable pigmentation of the resin and/or by surface treatment.

While the method is widely used and very good results may be obtained, there is still room for improvement in the quality of finish. Furthermore, the finishes currently obtained normally require at least two further treatments, namely staining and varnishing, in order to obtain an acceptable product, and these add significantly to the cost, especially since often more than one staining step is1 required. Moreover, the product recovered from the mold cannot be sanded because every scratch is highlighted in any subsequent staining treatment.

It is an object of the present invention, to reduce or avoid these disadvantages.

According to the present invention, there is provided a process for forming a product with a surface of molded synthetic resin having a simulated wood grain finish which includes the step of effecting contact between a surface of a moldable body of curable synthetic resin and a mold surface designed to form the simulated wood grain effect on said resin surface, wherein prior to effecting said contact, a part or all of the mold surface is coated with a colourant, such as a pigment or dye. having a colour which is different from the colour of the resin when cured, and which is transferred to the surface of the curable resin when contact is effected and retained on said surface when the molding is parted from the mold.

In one embodiment of the invention, the coating of the mold surface with the colourant is restricted to parts, only, of the mold surface. For example, the coating may be restricted to the higher areas so that on transfer to the molding it is concentrated in the lower areas or valleys of the surface of the molding. -3Where the coating is not limited to the higher areas of the mold surface, e.g. where the whole surface of the mold is coated, it nay be advantageous to treat the face of the molding so obtained to remove colourant selectively from parts of the surface; for example colourant may be removed from high points by abrasion, such as sanding. (In the process of this invention, sanding the molded product is not unacceptable because the product does not have to be stained after removal from the mold).

The colourant, e.g. pigment or dye, may be applied as a dry powder or as a suspension or solution in a suitable liquid medium which may be aqueous or non-aqueous; e.g. an ink. Application may be by spraying, wiping e.g. with a cloth, or any other suitable or convenient method.

Where a pigment is employed in suspension in a liquid medium the latter may suitably include a binder. Where the colourant is applied by wiping, the choice of material employed to carry the colourant will affect the distribution of the deposit. For example, if a relatively stiff pad is employed, depositions will tend to be limited to the peaks of the mold surface whereas a softer pad or cloth will deposit the colourant over a wider area.

In one particular embodiment, the deposition of colourant in the mold surface is achieved by wiping the surface with a carbon paper, coloured transfer paper or stiff pad coated with pigment. In general, this method will tend selectively to coat high points and possibly also shallow valleys of the molding but the lower parts of relatively narrow valleys will tend to remain uncoated. -1,If a powder or solution or dispersion, e.g. ink’ is applied with a cloth, the amount of surface coated will depend upon the choice of cloth and in particular its softness. With softer cloths, smaller proportions of the area, generally the deeper zone of the narrower valleys, will be left uncoated.

Spraying is a suitable procedure for coating the entire, or substantially entire, surface; however, it may be used also for coating selected areas, e.g. by use of masks.

Two or more different colours may be applied. For example, the whole surface may be coated with a first colour and then parts of the surface, e.g. the high points, selectively coated with a second colour. If desired, the first colour may be removed from the high points, e.g. by wiping, before the second colour is applied. In a modification of this procedure, the first colour may be applied so that, for example, high points and wide valleys are coated, but not the deeper zones of narrow valleys. The molded product will then have a surface exhibiting three different colours. Further variations may be achieved by selective removal of the colour or colours from the resultant molding, e.g. by sanding the high points.

By using three or more colours, even greater variation can be achieved and a wide variety of wood surfaces simulated.

The effect varies with the kind of wood grain surface simulated by the mold, the colour of the dye or pigment and the colour of the resin and the best results for any particular combination require trial and experiment. In general, however, it is desirable for the colour of the resin and the colour of the dye or pigment to provide a good contrast, e.g. as in a black pigment or dye and a pale colour for the resin. -5In general, a mold release agent will be applied to the surface of the mold prior to application of the colourant. In some cases, this will result in transfer of mold release agent to the surface of the molding and this transfer may be enhanced by the presence of the colourant. Where this occurs, the surface of the product can be provided with an attractive sheen by polishing.

In the products of the invention, the pigment or dye may be incorporated into the body of the resin as well as on to the surface, thereby providing a finish which is more resistant to damage.

The invention is now described in greater detail with reference to one embodiment thereof and with the aid of the accompanying drawings, wherein Figure 1 shows, in diagramatic and much enlarged form, a cross-section of a part of a mold whose surface is coated with pigment in accordance with the invention; Figure 2 shows in cross-section the surface of a molding’ obtained using the mold of Figure 1, Figure 3 is a photograph of a surface obtained by the process of the invention.

Referring to Figure 1, 2 is a mold having a surf ace with valleys 4 and peaks 6 and formed to impart a simulated wood grain finish to a synthetic resin molding. Suitably, the mold is obtained by casting a suitable mold-forming material, e.g. polyester, polyurethane elastomer ΙΕ 921277 -6or silicone rubber, against the surface of a sheet of wood in which preferably the surface grain has been exaggerated by previously soaking the surface of the wood in water to cause it to swell.

Prior to use, pigment 8 is applied to the mold surface. In the illustrated embodiment, it is applied to parts of the surface, specifically the higher areas and some parts of the shallower valleys. The coating is effected e.g. by wiping the surface with a carbon paper of a chosen colour or by applying powdered pigment with a cloth pad.

After the coating step, a layer of curable synthetic resin, e.g. polyester, having a colour which is a contrast to the pigment β, is applied to the mold surface preferably with the application of pressure to ensure good contact, and is allowed to remain in contact with the mold surface until cure of the resin is substantially complete. By means of the contact of the resin with the mold surface, the pigment 8 is transferred to the resin surface, producing the molding 10 illustrated in Figure 2, comprising resin layer 12 parts of the surface, and principally valley areas, of which are coated or impregnated with pigment 8.

As will be well understood by those skilled in the art, the resin layer may be the external layer of a complex molding which may, 'for example, include further backing layers of resin at least one of which may include filler and/or fibrous reinforcement. The molding having the resin layer as an outer face may also include one or more preforms such as of blocks of wood or rigid plastics foam which are located behind and bonded to the resin layer or layers. ΙΕ 921277 -7A typical surface obtained by the process of the invention using black pigment and a pale yellow or beige colored polyester resin is illustrated in Figure 3.

The wood grain effect on the surface of the molding of the invention is closer to the real thing than that produced by a corresponding process without the use of pigment and the product of the invention does not require staining prior to varnishing.

Moreover, by means of the invention a greater number of colours can be achieved in the panel and where the pigment or dye is incorporated into the resin layer the result is more resistant to damage from everyday use than a conventional stain finish.

Yet a further advantage of the invention is that the need for staining is avoided although the product may be stained if desired.

Another advantage is that the product more readily accepts stains and varnishes- This is believed to be due to the presence on or in the resin surface of pigment particles which enhances the ability of the surface to absorb the stain or varnish.

This is further improved by sanding or otherwise abrading the surface prior to staining or varnishing. Moreover, contrary to what is found with present resin moldings with wood-grain surfaces, sanding does not mar the finish. In fact, it can enhance the finish in some cases, e.g. where it is employed to remove pigment or dye from the high points of moldings obtained where the entire mold surface has been coated.

Claims

1. * CLAIMS

1. A process for the formation of a product with a surface of molded synthetic resin having a simulated wood grain finish, which process includes the step of effecting contact between a surface of a moldable body of curable synthetic resin and a mold surface designed to impress the simulated wood grain effect on said resin surface, wherein prior to effecting said contact part or all of the mold surface is coated with at least one colourant, such as a pigment or dye. having a colour which is different from the colour of the resin when cured and which is transferred to the surface of the curable resin when contact is effected and retained on said surface when the molding is parted from the mold.

2. A process as claimed in 1 wherein the high points of the mold surface are selectively coated with colourant.

3. A process as claimed in claim 1 wherein high points of the mold surface are coated with a first colourant and other areas of the mold surface are coated with a second colourant.

4. A process as claimed in any one of claims 1 to 3 wherein the mold surface is treated with mold release agent prior to applying the colourant or colourants. - 9

5. A process for the formation of a product with a simulated wood grain finish, substantially as described herein, with reference to the accompanying drawings.

56. A product having a simulated wood grain finish whenever formed by a process as claimed in any one of the preceding claims.