HK1102511B - Process for manufacturing embossed-in-register products - Google Patents

Description

Process for manufacturing precision-registered embossed products

The present application has application number No.02815741.9 filed on 12/7/2002, entitled "manufacturing process for precision emboss lamination" filed as a divisional application of PCT patent application.

Technical Field

The present invention relates to a laminate material. In particular, the present invention relates to a method of manufacturing a laminate material having a decorative pattern and a surface texture which is mechanically embossed to precisely coincide with the decorative pattern.

Background

Due to their look and feel, traditional building and decorative materials, such as fine wood, slate, granite, stone, brick, and concrete, are often preferred by consumers. However, these materials are expensive to produce and install. For example, while solid wood flooring has a highly expensive luxurious look and feel, the materials and labor required to install such flooring can be very expensive in practice.

There are many alternatives to conventional building and decorative materials, including laminates and High Pressure Laminates (HPL). However, generally none of these alternatives have the realistic look and texture of traditional building and finishing materials. For example, most alternatives with a wood grain pattern on the outer surface appear to be counterfeit and thus can be easily distinguished from traditional wood. Also, while high quality laminates or HPLs may appear as traditional wood, their texture may readily reveal that they are not.

One problem with most alternatives to conventional building and decorative materials is that their surface texture does not match their decorative pattern. For example, the visual appearance of the knots does not match the surface texture characteristics of the knots. This significantly reduces the consumer appeal of such alternatives.

One existing solution to match the surface texture of a replacement material to its decorative pattern is to perform a chemical embossing process. In the chemical imprinting process, the surface texture of such substitute materials is formed by chemically reacting the ink forming the decorative pattern with a medium added to the subsurface layer. Although somewhat successful, the resulting surface texture tends to lack the texture clarity and three-dimensional characteristics of conventional materials.

Another alternative to conventional building and finishing materials is DPL panels (direct compression laminates). However, this alternative also does not produce satisfactory results.

Another method of forming surface textures for alternative materials has been proposed, which is to mechanically emboss DPL plates. This approach is of interest because of the ability to create high texture definition and high quality three-dimensional features. However, since it is extremely difficult to precisely perform the mechanical embossing process in superposition with the decorative pattern, the mechanical embossing process for the surface texture to match the decorative pattern so as to make the final product look and feel as if it were a conventional building or finishing material (hereinafter referred to as a precision superposition embossing process) is also problematic. Also, the difficulty in accurately maintaining the registration of the precision embossings during the production process has prevented the practical use of mechanical precision embossing systems.

Accordingly, there is a need to provide a viable method of manufacturing alternative building or finishing materials, wherein the alternatives have the realistic look and feel of traditional products. It would be highly advantageous to provide a method of mechanically producing a substitute having precisely registered embossings. It would be further advantageous to provide a method of mechanically producing a commercially available alternative with precisely registered embossments.

Disclosure of Invention

The gist of the present invention is to provide a method of manufacturing alternative building and decorative materials having a decorative pattern and a surface texture which is mechanically embossed to coincide exactly with the decorative pattern.

The invention provides a method for manufacturing a laminated product, which comprises the following steps:

positioning a resin-impregnated sheet having a decorative pattern on a board so that the decorative pattern is at a predetermined position on the board;

positioning the resin-impregnated sheet and the board within a press having a platen with a three-dimensional surface such that the decorative pattern is disposed at a predetermined position relative to the platen within the press; and

curing the resin at a predetermined temperature while pressing the resin-impregnated sheet and the panel at a predetermined pressure using the press plate to produce a laminated product;

wherein the surface texture of the produced laminate product is embossed in exact register with the decorative pattern.

Advantageously, the laminated product is a floor, the lamina is paper and the board is a fibreboard, such as a medium or high density fibreboard or a particle board.

Wherein the step of placing the resin-impregnated sheet on the sheet comprises hobbing a reference edge on a sheet and subsequently using the reference edge to place a sheet of paper having a decorative pattern and impregnated with resin on the sheet so that the decorative pattern is in a predetermined position relative to the reference edge. Advantageously, the paper is electrostatically adhered to the sheet material. The sheet material and paper are then moved into a press where they are precisely positioned using the reference edges as guides so that the decorative pattern is in a predetermined position relative to a platen having a predetermined temperature. The press is closed and the hot platen presses the paper into the sheet with a predetermined force for a predetermined period of time.

It is beneficial to carefully control the size and material composition of the resin and paper. Advantageously, the paper is manufactured by the same supplier on the same machine, using materials from the same supplier, and great care needs to be taken with respect to the cellulose material, the direction of the reel winding and the reel winding tension. Advantageously, the resins are manufactured by the same supplier using materials from the same source, using the same reaction vessel, and great care is required for the mixing operation of the materials and the solids content.

The platen, having a three-dimensional surface, is preferably manufactured so that the surface of the platen matches the decorative pattern when the platen is heated to its operating temperature.

In practice, it is generally preferred to use a slow curing resin and the press operating temperature is lower than in the prior art. This may improve the quality of the final surface.

If the surface texture is rough enough to significantly affect the distribution of pressure on the paper and board during the embossing process, the board can be suitably hollowed out prior to the embossing operation to equalize the pressure distribution.

Drawings

Like reference numbers and letters identify corresponding parts throughout the several views, wherein:

FIG. 1 illustrates a substrate assembly suitable for being mechanically subjected to a precision overlay imprint process;

figure 2 shows a press for producing a product with precisely congruent embossings;

figure 3 shows a product with a precise embossing of the lamination.

Detailed Description

The subject matter of the invention is incorporated in a method described later which mechanically produces an architectural or decorative product with a precise register embossing. It must be understood, however, that while the exemplary embodiment is suitable for manufacturing products with precise embossing of the lamination, those skilled in the art of application will realize numerous alternatives and modifications. Accordingly, it is intended that the present invention extend to all such alternatives and modifications as fall within the broad generic terms of the appended claims.

Direct Pressure Laminates (DPLs) are known per se. Referring now to fig. 1, conventional direct-pressure laminates are typically made from a single substrate 4The substrate 4 is then a medium or high density fiberboard or chipboard. Next, one or more layers 6 of kraft paper impregnated with a specific resin (only one layer is shown in fig. 1 for clarity) are placed on and/or under the base layer 4. Subsequently, a decorative cellulose paper layer 8, about 0.15 mm thick and impregnated with melamine solution, was placed on the kraft paper layer. Above the decorative cellulose paper layer 8 is one or more protective coverings 10. The coating is made of a sheet of highly abrasion-resistant paper having silicon carbide (Al) impregnated in a melamine solution₂O₃). It is also possible to include different paper between the decorative cellulosic paper layer and the substrate.

The structure shown in FIG. 1 is then pressed under heat (180-220 deg.C) and pressure (about 20-30 kg/cm) until the resin is thermally cured. The result is an extremely rigid and durable product known as a "Direct Pressure Laminate (DPL)".

The subject matter of the present invention relates to an improved direct press laminate. In these direct-pressed laminates, the surface texture of the final product is precisely registered with the decorative pattern on the paper ply. The surface texture is produced using a press such as that shown in fig. 2. Referring to fig. 2, to produce a direct press laminate in accordance with the principles of the present invention, a base sheet 20 (a) a decorative paper sheet 14 impregnated with melamine resin and one or more protective covers 16 (and may have other thin layers such as a base layer 18) are precisely placed in a press. The press machine includes a base 22, an upper press block 24, and a press plate 26 having a three-dimensional surface. It will be apparent that the surface of the press plate (described in more detail below) includes ridges and/or depressions that align with the decorative pattern on the decorative paper layer 14. The base sheet 20, the decorative paper layer 14 and the protective covering 16 (if present, including the base layer 18) are then heated to 160-220 ℃ and pressed together under a pressure of 20-40 kg/cm for 20-60 seconds. This will cause the melamine to cure and form a direct laminated product with precisely registered embossments.

Referring now to fig. 3, the final direct-pressed laminate 40 has a surface texture embossed by the press plate 26 that precisely coincides with the decorative pattern 28 on the decorative paper layer 14. By precision ply it is meant that the embossed texture conforms or matches the decorative pattern on the decorative paper ply 14 to provide a realistic imitation of natural material.

The various layers shown in fig. 2 are similar to those in the prior art direct compression laminate shown in fig. 1, but the layers in fig. 2 have closely controlled parameters (discussed later). The base plate 20 may be a medium density or high density fiberboard (particle board). Before entering the press, a decorative paper layer 14, one or more protective overlays 16, and a bottom layer 18 (if present) are placed on a base sheet 20. Advantageously, the thin layers are electrostatically attached to the base plate. Also, the protective cover 16 and the base layer 18 may be impregnated with a resin that need not be the same melamine resin used to impregnate the decorative paper layer 14.

Although the foregoing generally describes the pressing and heating operations when making products with precisely registered embossments, other knowledge is useful.

First, various parameters of the resin and paper must be controlled to ensure dimensional exactness, particularly swelling, such as during the impregnation process. In particular, the paper must be highly homogeneous in order to obtain carefully controlled phenomena of swelling of the long and short sides. It is convenient to ensure that the papers come from the same manufacturer. Also, the manufacturer must only use cellulose pulp from the same source. The manufacturer will also make all papers on the same paper machine using paper fibers with carefully controlled ash content and with uniform color. In addition, the manufacturer must supply the paper from the same location on the manufacturing reel. Also, the paper manufacturer must not rewind the paper because it may change the orientation of the paper fibers. The foregoing helps to ensure that the impregnated paper will always have the same final dimensions.

Also, a storage warehouse for supplied paper before use is also important. Time, temperature and humidity must be carefully controlled to help ensure uniform and consistent paper.

All resins (such as melamine) must also be carefully controlled. It is convenient to ensure that the resins are from the same manufacturer. Also, the manufacturer must only use (melamine) powder from the same source, must ensure that all additives are of the same quality, and come from the same source, and must mix the resins in the same reactor. Great care must be taken to ensure that the resin supplied has a constant solids content. Also, the foregoing helps to ensure that the impregnated paper will always have the same final dimensions.

Also, the infiltration process itself must be carefully controlled. When the paper is dipped into melamine resin to wet the paper, the paper must have a constant and uniform melamine loading. This ensures homogeneous absorption of the resin in the paper. To help ensure a constant and uniform load, the same wetter must be used for all sheets. Also, the belt tension and belt sway for the wetter, which are important to the end result, must be very precisely controlled.

Tight control of the aforementioned paper and resin is also important. Since the texture of the decorative pattern is impressed into the soaked paper, the size of the soaked paper needs to be accurately known in order to obtain a good quality product. Once these dimensions are achieved, a pre-formed platen may be used to perform the precision stack-up stamping operation.

The platen must be carefully designed so that it has the proper dimensions at the operating temperature. When the platen is in the press, the platen is hot, which causes the platen to expand. When the platen expands, the texture of the platen must match the decorative pattern on the soaked decorative paper. Therefore, the size of the decorative pattern must be adapted to the amount of expansion of the heated platen. The information of the decorative pattern is provided to the manufacturer of the press plate so that the press plate is manufactured by the manufacturer of the press plate to be properly superimposed with the decorative pattern when heated.

With a suitably soaked paper and a suitably designed press plate, a precision laminating and embossing operation can be performed. However, great care must be taken to place the soaked decorative paper ply 14 on the base sheet 20 relative to the press sheet in order to obtain a good quality of precision ply-embossing. Consideration must be given to the fact that when the press is locked and the board is subjected to pressure, it must be ensured that the structure of the press plate coincides with the decorative pattern of the paper.

The coincidence phenomenon is achieved using the following general process. First, the base plate 20 is milled by removing 2 or 3 mm from each edge. This results in several datum planes, sheet edges and a sheet with closely controlled dimensions. Next, a soaked decorative paper layer 14 is carefully placed on the base plate 20 using a positioning system that uses the edge of the base plate 20 as a reference, the outer dimension of the paper layer 14 being 8 or 10 mm smaller than the base plate 20.

The decorative paper layer 14 is preferably attached to the base sheet 20 using static electricity. This avoids relative movement as the sole plate 20 advances along the production line. Also, the protective covering 16 (and possibly the bottom layer 18) is also attached to the base plate 20.

The decorative paper layer 14/base sheet 20 is then placed on a carriage from which it is fed into the press. The carriage advances into the press, rests, and delivers the decorative paper layer 14/base sheet 20 structure to the positioning tweezers. The tweezers gently placed the decorative paper layer 14/base sheet 20 structure on the lower press plate. The carriage is then moved out of the press.

After the decorative paper layer 14/base sheet 20 structure is placed on the lower press plate, another positioning system then precisely positions the structure at a predetermined location within the press. Such a positioning system also preferably uses a milled reference edge on the sheet material to position the decorative pattern relative to the platen 26. The press is then locked, the interior of the press is heated to its operating temperature, and the upper press block 24 presses the press plate 26 into the decorative paper layer 14/base sheet 20 structure, fusing them together. The carriage is then moved back into the press and the final product is removed.

Certain aspects of the precision overlay imprint process are important. In particular, in order to avoid the problem of air voids, it is preferable to soak the paper with a slow curing melamine. This means that the press will operate for a longer period of time and at a lower operating temperature than in the prior art.

The aforementioned precision-overlay imprint process is suitable for imprint surface textures that are less than 0.2 mm deep, which can cause problems. The problem is that the deeper the surface texture, the larger the platen protrusion is required, which tends to affect the even distribution of pressure across the surface of the sheet. This can lead to distortion and inaccuracies in the final product. One solution to this problem is to first cut out the surface of the board at those locations where a deep surface texture is desired. Of course, it is also important to accurately position the hollowed-out portion. This hollowing process can be carried out in the pressing line simultaneously with the aforementioned hobbing of the periphery. Advantageously, the reference edge is used to locate the cut-out. Alternatively, the hollowing operation may be performed in another production line.

The foregoing has exemplified a method of manufacturing a conventional building and trim material substitute having a precisely congruent decorative pattern and an embossed surface texture. This method has a number of manufacturing advantages over the prior art. Those skilled in the art of application will appreciate that there are numerous additions, modifications and improvements. Thus, it is to be understood that even though numerous characteristics and advantages of the present invention have been set forth, or apparent to those skilled in the art, the disclosure is illustrative only, and changes may be made in detail. Accordingly, it is intended that the invention cover all embodiments falling within the broad meaning of the appended claims.

Claims (13)

1. A method of manufacturing a laminated product comprising:

hobbing a reference edge on a plate;

positioning a resin-impregnated sheet having a decorative pattern on the board such that the decorative pattern is in a predetermined position on the board relative to the reference edge;

positioning the resin-impregnated sheet and the board in a press having a platen with a three-dimensional surface such that the decorative pattern is positioned at a predetermined location relative to the platen inside the press using the reference edge; and

curing the resin at a predetermined temperature while pressing the resin-impregnated sheet and the panel at a predetermined pressure using the press plate to produce a laminated product;

wherein the surface texture of the produced laminate product is embossed in exact register with the decorative pattern.

2. The method of making a laminated product according to claim 1, wherein said laminated product is a flooring.

3. A method of manufacturing a laminated product according to claim 2, wherein the sheet is paper.

4. A method of manufacturing a laminated product according to claim 3, wherein the sheet material is a fibreboard.

5. The method of manufacturing a product according to any of the preceding claims 1 to 4, further comprising: and performing hollow-out treatment on the surface of the plate.

6. A method of manufacturing a product according to any of the preceding claims 1 to 4, wherein the predetermined temperature is between 160 and 220 ℃.

7. A method of manufacturing a product according to any of the preceding claims 1 to 4, wherein the predetermined pressure is between 20 and 40 kg/cm.

8. The method of manufacturing a product according to claim 7, wherein the pressure is applied for 20 to 60 seconds.

9. The method of manufacturing a product according to any of the preceding claims 1 to 4, further comprising: a protective coating is placed over the resin impregnated sheet.

10. The method of manufacturing an article of claim 9, wherein said protective cover is impregnated with a resin.

11. The method of manufacturing a product according to any of the preceding claims 1 to 4, further comprising: a bottom layer is placed under the sheet.

12. The method of manufacturing a product according to claim 11, wherein the bottom layer is impregnated with a resin.

13. The method of manufacturing a product of claim 11, further comprising: the thin resin-impregnated layer having a decorative pattern is produced by impregnating a kraft paper with a melamine resin.