JPH0152066B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to the manufacture of decorative plastic laminates, which are widely used in making furniture, counter surfaces, panels, or other decorative or functional surfaces.

The techniques for making such laminates are well known. A core board or back board is formed by stacking multiple sheets of resin-impregnated kraft paper. The resin used is
It is a heat-curing type such as phenol formaldehyde. A decorative sheet with a printed design or solid coloration impregnated with melamine resin is placed on top of the core board, and an overlay sheet, usually melamine-impregnated alpha acellulose paper, is overlaid on top of the decorative sheet. In some instances, the overlay sheet may be omitted, especially if the final product is solidly colored. A panel of particle board may be substituted for the core sheet.

The above assembly of resin-impregnated sheets is fixed between hot press plates or molding plates and heated and pressurized so that they adhere firmly to each other when the resin hardens. A release sheet, such as non-adhesive paper, plastic film or aluminum foil, is sandwiched between the backboard and the decorative surface to prevent the decorative surface and the backboard from adhering.

Various techniques have been developed to render decorative surfaces of laminates into textured surfaces. US Pat. No. 1,742,516 describes a method for embossing a laminate by using an engraved backboard having a design engraved into it. US Pat. Nos. 1,997,358 and 2,133,081 describe the texturing of plastic laminates using embossed metal backing plates.

Since engraved or embossed metal backing plates are expensive to manufacture and have a short lifespan, subsequent efforts have been directed primarily toward alternative methods. U.S. Pat. No. 2,606,855 describes a method of using a master to create multiple textured backboard plates from stacks of resin-impregnated paper. A similar technique using an embossed or debossed plastic laminate as a molding plate is disclosed in U.S. Pat.
No. 3303081 and No. 3311520. US Pat. No. 3,373,068 describes the use of particulate materials on decorative sheets to impart texture.

My patent No. 3,616,011 describes another method of making a textured molded backplate in which a textured master is sandwiched between a pair of thin flexible resin-impregnated sheets. These sheets are pressed tightly against the recessed surfaces of the master mold and the resin is cured. A resin set sandwich of the master pattern and sheet is then used as a master forming plate.

It is often desired to produce laminates that look like other products, a good example being wood grain surfaces. In such a case, it is possible to use a decorative sheet with colored wood grain printed on the top surface,
This decorative surface may then be textured in a subsequent molding step. However, it is usually not possible or inconvenient to impart a texture that matches the printed pattern, and the resulting product has no combined texture and no color differentiation to the wood grain, saw marks or recessed areas of the wood. It does not have the appearance of naturally colored wood, where the grain is enhanced by absorption.

The present invention provides great realism that could not be obtained conventionally.
Figure 2 illustrates improvements in the production of textured decorative laminates that allow for warmth and contrasting textures.

In the production of textured decorative laminates, a release sheet with a pigmented surface is applied to the decorative surface before the laminate is pressed with the textured forming plate. The release sheet may, for example, consist of a sheet of polymer having a thin layer of ink applied substantially uniformly over the surface against which the panel or laminate is formed.

When the laminate is pressed and heated, the pigment is transferred to a uniformly textured surface, the color of which is chosen to contrast with the color of the decorative sheet.

After lamination is complete, the release sheet is removed to expose a textured surface that is substantially uniformly colored with pigment. The decorative surface is then subjected to surface scrubbing, brushing or light abrasion to the extent necessary to remove the color from the higher or embossed areas while leaving more color in the lower areas, thus enhancing the texture or Perform shading,
Texturing gives added visual dimension to the appearance of surfaces.

The migrated pigments are absorbed into the decorative surface during the application of heat and pressure, especially in the debossed areas, and the pigments that are not removed by subsequent rubbing are considered to have a high degree of adhesion to the product. ing. By applying a liquid pigment to a laminate with a relatively non-porous surface finish and then rubbing the surface,
Equivalent results are not achieved.

Any of the well-known methods of texturing laminates can be used to carry out the method of the invention. For example, wood grain, woven fabric, decorations, letters or printing,
and many other textures are possible. The method of manufacturing textured laminates from textured sheets is conventional and the present invention provides color enhancement to the textured surface.

Core sheets or other suitable backing sheets, decorative sheets and overlay sheets, as well as the resins and processing conditions used to impregnate such sheets, are conventional as described in the above-identified patents, which are hereby incorporated by reference. Follow the method. In conventional practice, the core board is made from a plurality of resin-impregnated kraft sheets.
These sheets are usually impregnated with phenolic resin, at least partially dried, and then stacked in overlap. The number of sheets used is variable and usually this number varies between three and six. Other core board materials may also be used, such as particle board. A resin-impregnated decorative sheet is placed directly on the core sheet stack or backing sheet,
In a preferred embodiment, this material has a color thereon;
A sheet with printing or other decoration, for example a print resembling a woodgrain panel. A protective overlay sheet of delicate paper, such as alpha cellulose, is often layered over the printed sheet. This overlay and printing sheet contains thermosetting resin,
Preferably, a high grade thermosetting resin such as melamine formaldehyde resin is impregnated. On the other hand, the decorative sheet may be replaced with metal foil.

In normal practice, a sandwich of the above material is placed between a pair of rigid backing plates.
The backing plate facing the decorative sheet has the desired textured surface applied by conventional, well-known methods, and a release sheet is placed between the backing sheet and the outer sheet of the laminate. It will be destroyed. This assembly is placed in a heated press and the sandwich is heated and pressured for a time sufficient for the resin in the laminate to cure, i.e. typically 500-2000 p.si, 200°-400° and 15-60 minutes. multiply.
The resulting product is a rigid laminate with a hard durable decorative and textured surface.

In a preferred embodiment, the textured plate is prepared by any suitable method. For example, the backing plate may be a hard metal plate having the desired texture etched by conventional methods.

Another method of preparing a textured plate is described in US Pat. No. 3,616,011. As described in this patent, a disposable master textured panel or sheet is sandwiched between a pair of resin-containing or impregnated overlay sheets slightly larger than the master. The overlay sheet and the curable resin contained therein may be any of a wide variety of materials, including various thermosetting resins such as melamine, phenolics, epoxies, urea-formaldehyde, and the like. The overlay sheets are each covered with a release sheet, which in turn is backed with a stack of padded sheets, such as sheets of kraft paper.

The resulting assembly is then placed in a forming press between a pair of backing plates, and the assembly is heated and pressed between the backing plates in a conventional manner until the resin is cured. Upon curing, the overlay sheet joins the textured core and assumes the texture of the core. The resulting laminate, textured on one or both sides, is used as a forming plate for making textured decorative laminates as described above.

The method of applying colored highlights of the present invention is performed as part of forming a textured decorative laminate. The color is applied to the decorative surface during the pressing process, and excess color is removed from the textured surface after completion of the molding operation.

To carry out the method of the invention, a special release sheet is used and is an important feature of the invention. The release sheet used is first coated with pigment on one side and the colored side is placed facing the decorative surface prior to pressure forming of the textured laminate.
The color of the pigment is preferably chosen to be darker than the color of the decorative sheet, or in any case preferably a contrasting or accentuating color.

Although any form of pigment may be used, the form of the pigment used must be compatible with its application to the release sheet. For this purpose, therefore, preference is given to pigments supported in a solvent and binder system that is coated onto a release sheet, such as a printing ink, and dried after application. It is not necessary to apply the ink to the release sheet according to a pattern, and in fact a substantially uniform and non-pattern application is preferred to ensure complete coverage of the decorative surface. Uniform coverage of the ink onto the release sheet by conventional gravure methods has been found suitable for this purpose.

The material for the release sheet may be selected from any of the commonly used materials and includes foils, polymeric films and treated paper films. Polypropylene film is particularly preferred because of its ability to release ink under the heat and pressure conditions used in the lamination process.

The decorative laminate, pigmented release sheet, and textured backboard components are then assembled as a sandwich as described above, and the components described above are assembled at pressures and temperatures sufficient to effect curing and bonding of the resin-impregnated sheets. compressed in a similar way. During the lamination process, the textured surface of the board is applied to the decorative surface, and similarly, the release sheet conforms to the irregular surface to evenly transfer the pigment on the top surface onto the decorative surface of the laminate. After curing, the release sheet is removed from the textured decorative surface, leaving the surface substantially uniformly coated with pigment.

Under large-scale production conditions, it is preferred to use a caul plate with textured surfaces on both sides, since the assemblage of the caul plate and resin-impregnated paper mass can be compressed and heated simultaneously. For example, five backing plates can be used in one molding operation to produce ten decorative panels.

In the production of simulated wood panels, wood grain printed sheets are used and a wood grain texture is imparted to the laminate. The problem of accurately aligning the patterns is eliminated because the print sheet pattern and the texture pattern do not need to match to achieve the desired result.

The pigmented textured surface of the laminate is subjected to an operation that removes some or all of the pigment remaining on the embossed areas from those areas of the surface, leaving a significant amount of pigment in the debossed areas. This operation, which can be accomplished by rubbing or brushing the surface, exposes the subtle light and shade or texture of the ridge wood grain and emphasizes the three-dimensional shadow effect. A suitable method is to brush the textured surface with a rotating bristles or tampico brush, preferably in the direction of the grain pattern. Any of the equipment commonly used for clouding scrubbing operations to reduce the gloss of decorative surfaces of laminates, and similar methods for mechanically removing pigment from high spots, are effective.

The pigments preferably used are those with high adhesion, but in all cases some of the pigment migrates to the resin surface, especially in debossed areas exposed to high molding pressures, and when the resin is cured. It is believed that it binds within it.

The resulting laminate thus has a textured surface with a higher concentration of pigment in the debossed areas than in the embossed areas. With the invention, various effects can therefore be created, especially with the use of contrasting colors in decorative surfaces and pigments.

Claims (1)

[Claims] 1. Making an assembly of sheets impregnated with a thermosetting resin, placing a release sheet on the assembly, heating and pressurizing these together to join the assembly to form a laminate. in a method of imparting color enhancement to a decorative laminate with a textured surface obtained by: using a pigmented release sheet; releasing the pigment onto the textured surface during a molding operation; and the pigmented textured surface to enhance the color by removing some of the pigment. 2. The method according to claim 1, wherein the release sheet is a polypropylene film. 3. The method of claim 2, wherein the pigment is a liquid ink that is applied to a film and dried thereon. 4. The method of claim 3, wherein the ink is applied substantially uniformly to the film. 5. The method of claim 1, wherein rubbing the pigmented textured surface is brushing with a rotating brush. 6. The method of claim 1, wherein the outer surface is a printed wood grain pattern and the pigment is of a contrasting color to the outer surface. 7. A process for producing a textured decorative laminate in which the pigment is transferred to the laminate by compression molding using a pigmented release sheet; and a process for removing a portion of the applied pigment by rubbing the surface of the pigmented textured laminate. A method of imparting shine or shading to a decorative laminate comprising: rubbing the textured laminate so that more is removed from raised areas than from lowered areas. 8 A decorative laminate having a textured surface is formed by forming an assembly of resin-impregnated sheets, covering the outer surface of this assembly with a release sheet, and heating and pressing this assembly between a pair of forming plates to form a laminate. In this case, if one of the sheets has a textured surface and is designed to give a textured finish to the laminate surface facing the release sheet, the textured surface of the laminate A method for imparting color enhancement to a laminate includes the step of preparing a release sheet coated with pigment such that the pigment migrates from the release sheet to the laminate surface while the surface is being textured by heating and pressure. removing the release sheet to expose the pigmented textured surface after the laminate is formed; and removing more pigment from raised areas of the textured surface than from lowered areas; The method described above, comprising the step of: rubbing the surface.