AU684426B2 - Laminated products - Google Patents

Description

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1- P/00/01 1 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: Laminated Products e S

S

5 C S 0000 The following statement is a full description of this invention, including the best method of performing it known to us: GH&CO REF: P2351 1C/JT 23511 C/418

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The present invention relates to laminating products and, in particular, concerns applying a decorative design by laminating to a substrate.

One example of the application of the invention is to the decoration of melamine articles, such as plates.

Australian patent 459,410 (25,681/71) describes a process for laminating articles, such as melamine plates, wherein a sandwich is formed of a surface sheet of non-pigmented paper impregnated with thermosetting melamine-formaldehyde resin, a decorated sheet of ordinary paper and an underlying sheet of paper impregnated with thermosetting melamine-formaldehyde resin. This sandwich is laminated to a substrate by applying heat and pressure to the assembly to cause bonding and to form a decorated article.

According to the present invention, there is provided a method of 15 producing a decorated laminated rigid product comprising printing a digitally stored image of a decorative material onto a coated paper to form a relatively high definition print, locating the print beneath a paper surface sheet impregnated with a thermosetting melamine-formaldehyde resin, o o So: positioning a second paper sheet impregnated with a thermosetting melamine-formaldehyde resin below the print so as to form an assembly comprising the paper surface sheet, the print and the second paper sheet, and locating the assembly over material for forming a rigid substrate and applying heat and pressure to bond the assembly and the substrate to form the decorated laminated rigid product, the thermosetting resin providing a transparent protective covering over the print and bonding the print onto the product.

19 Preferably, impregnation of the surface sheet and of the second sheet is such that the weight of resin is one and a half to three times the weight of the paper.

Preferably, the paper onto which printing occurs has low sheen, such as Epson Special Coated Paper, suitable for 720 dpi printing (product code #S041026) or a similar paper, such as Hewlett Packard Inkjet Premium Paper S o 0 0 e o I I -3 (product code #516342).

Preferably the method is operated by first scanning artwork such as photographic print into a computer to provide digitally stored information for the printing process. Successful scanning has been achieved of photographo using an Epson GT 9000 colour image scanner with Adobe Photoshop software. However, similar products can also be used.

The printing process, for example, can be provided for by a high quality colour printer such as an Epson Stylus Pro printer, which operates at about 720 dpi.

Surprisingly it has been found that in contrast to the prior art method, which has been restricted to use of certain types of coloured markers on bond paper, high quality results can be achieved with embodiments of this :invention without any degradation or blistering of the Sprinted image and significantly, notwithstanding the nature of the paper and the type of ink used in the printing process, good lamination occurs.

In another aspect, the invention extends to a laminated product produced by the method.

For illustrative purposes examples of the invention will now be given: Example 1 An ordinary coloured photograph was scanned using an Epson GT 9000 colour image scanner using Adobe Photoshop software and a digitally stored image was thus recorded using a personal computer. The computer was connected to an Epson Stylus Pro colour printer and Epson special coated paper for 720 dpi printing was used. A print was made.

A surface sheet was prepared by impregnating a sheet of an alpha cellulose paper with an aqueous solution of a melamine-formaldehyde reaction product.

Before impregnation, the alpha cellulose paper was .0045 inch thick and weighed 4.4 grams per square foot. After impregnation, the surface sheet was dried at 270 0 F for S:23511C 17.7.96 -4about 1 minute. The dried impregnated surface sheet was approximately .007 inch thick and consisted of 31% by weight of alpha cellulose and 69% by weight of melamineformaldehyde reaction product.

An assembly was created comprising a first impregnated sheet, the colour print and a second impregnated sheet, each being circular in shape and with a diameter slightly more than the diameter of the dinner plate to be decorated.

Finely divided commercial alpha cellulose-filled melamine-formaldehyde moulding composition, in an amount sufficient to produce a dinner plate, was consolidated under pressure into a preform, was preheated, and was placed between the dies which were used to form the dinner plate. The dies were at a temperature of 315 0

F,

and they were closed upon the preform of the moulding :composition under a pressure of about 3,000 lbs per square inch, and were held closed under that pressure for seconds. The dies were then opened, and a subassembly of the sheets consisting of the non-impregnated printed sheet with the printed side uppermost, between two impregnated sheets, was placed on top of the moulding composition and the dies were then immediately closed to hold the assembly under the same pressure and temperature for 85 seconds. The dies were then opened and the dinner plate was ejected.

The method thus produced a rigid melamine plate formed under heat and pressure and incorporating an assembly which is bonded therewith as surface decoration.

The manufacturing techniques are as described in patent 459410.

The surface sheet which is used in producing a decorated moulded article consists of unpigmented paper impregnated with 1% to 3 times its weight of a thermosetting aminoplast. The paper used for impregnation with a thermosetting aminoplast preferably consists of a substantially pure cellulose. For example, the paper may consist of 100% alpha cellulose fibre, or S:23511C 17.7.96 5 it may consist of a mixture of alpha cellulose fibre and rayon fibre, the proportion of each fibre usually being between 40% and 60% by weight.

The additional sheet of paper, impregnated with a thermosetting aminoplast, interposed between the decorated paper sheet and the resin-impregnated moulding composition serves as a wick for supplying the fused aminoplast to the underside of the decorated paper sheet immediately after the application of heat and pressure to the assembly. Thus the additional paper sheet may be made of any desired material which can be impregnated with a thermosetting aminoplast.

In the impregnation of a paper sheet which is to be used as the surface sheet (or as the additional sheet interposed beneath the decorated paper sheet), the thermosetting aminoplast preferably is applied in the form of an aqueous solution. The concentration of the impregnating solution may be any concentration which makes it possible to impart the desired amount of the aminoplast to the paper by an impregnating operation.

Ordinarily the concentration of an aqueous solution of the aminoplast is from about 30% to about 70% solids.

A solution of a thermosetting aminoplast may be used to impregnate the paper in the usual manner. A continuous web of paper may be fed from a supply roll, and may be impregnated by means of coating rolls, or by 000 passing it beneath the surface of the solution.

Preferably the paper is initially impregnated by means of rolls and then is passed through the solution.

Although the preferred aminoplast for use in the practice of the present invention is a melamineformaldehyde reaction product, other amino triazines or other aldehydes, such as the amino triazines and aldehydes listed in US Patent No. 2,841,571, may be used in preparing the aminoplast.

One amino triazine which may be used in place of melamine is gamma-methyl-gamma-acetyloimeloguanamine.

Another amino triazine which may be used in place of S:23511C 17.7.96 6 melamine to produce an aminoplast for use in the practice of the present invention is 2-methyl glutaroguanamine.

Either of those amino triazines, which are diguanamines, may be used to replace all or part of the melamine, for the reaction with formaldehyde to produce an aminoplast for use in embodiments of the invention. Also, a monoguanamine may be used to replace part of the melamine. For example, the resistance to coffee staining may be improved by replacing as much as 80 vol% of the melamine with benzoguanamine.

If a decorated moulded article having extremely high heat resistance and water resistance is not required, the cost of manufacture can be reduced by using a commercial water-soluble urea-formaldehyde reaction product as the aminoplast.

The resin impregnated moulding composition may be any finely divided composition such as melamineo formaldehyde or urea-formaldehyde moulding composition.

For example, a solution of a melamine-formaldehyde reaction product which is the same as the solution used to impregnate the surface sheet may be employed to impregnate bleached sulfite pulp, or any other cellulosic 'filler. The dried impregnated filler, which preferably Oe S"contains about 60 to 75% by weight of the formaldehydemelamine reaction product and form about 25 to 40% of cellulose, is ground to a fine powder, together with 0" modifiers such as pigments, zinc stearate or other lubricants, and phthalic anhydride or other acidic materials which serve as curing catalysts.

EXAMPLE 2 A side plate was formed using the same steps as in example 1 except the side plate had an initial moulding of the plate body portion for 50 seconds and the step of bonding the assembly to the surface of the substrate was achieved in 70 seconds.

S:23511C 17.7.96

Claims (10)

1. A method of producing a decorated laminated rigid product comprising printing a digitally stored image of a decorative material onto a coated paper to form a relatively high definition print, locating the print beneath a paper surface sheet impregnated with a thermosetting melamine- formaldehyde resin, positioning a second paper sheet impregnated with a thermosetting melamine-formaldehyde resin below the print so as to form an assembly comprising the paper surface sheet, the print and the second paper sheet, and locating the assembly over material for forming a rigid substrate and applying heat and pressure to bond the assembly and the substrate to form the decorated laminated rigid product, the thermosetting resin providing a transparent protective covering over the print and bonding the print onto the product.

2. The method according to claim 1 and further comprising taking a colour photograph and digitally scanning the photograph into a computer to form the digitally stored image which is then used for the remaining steps *of the method. *a

3. The method according to claim 2 wherein the method comprises Susing an Epson GT 9000 Colour Image Scanner with Adobe Photo Shop S:a. software.

4. The method according to any one of the preceding claims and wherein the printing step is effected using the inking technology used with an Epson Stylus Pro printer or a functionally equivalent printer using coated S printing paper for 720 dpi printing of the type known as Epson Special ~eI I ,I 8 Coated Paper or Hewlett Packard Inkjet Premium Paper or functionally equivalent paper.

The method according to any one of the preceding claims and wherein impregnation of the surface sheet and the second sheet is such that the weight of resin is in the range of 1.5 to 3 times the weight of the paper.

6. The method according to any one of the preceding claims wherein the material for forming the rigid substrate comprises alpha cellulose-filled melamine-formaldehyde moulding material and the method further includes consolidating a sufficient quantity of this material under pressure into a iii" preform which is formed into a plate-like object under heat of about 31 rc and pressure of about 3,000 pounds per square inch for a time of about seconds prior to application of the assembly thereto, the method further seat comprising applying pressure and heat for about 85 seconds to form the decorated laminated product.

7. A decorated laminated rigid product produced by the method of any one of the preceding claims.

8. A laminated product comprising a rigid substrate to which a decorative assembly is bonded under heat and pressure, the decorative assembly comprising a paper surface sheet which was impregnated with a thermosetting melamine-formaldehyde resin, a coated paper sheet disposed beneath the surface sheet and carrying a digitally printed image of decorative material on its face adjacent the surface sheet, and a second -e re I 9 paper sheet which was impregnated with a thermosetting melamine- formaldehyde resin disposed below the coated paper, the assembly being bonded to the substrate, with the surface sheet providing a transparent protective covering to the coated paper.

9. A decorated laminated rigid product produced substantially as herein described with reference to Example 1 or Example 2. A method of producing a decorated laminated rigid product substantially as herein described with reference to Example 1 or Example 2, Dated this 21 day of August, 1997 MAECHER PICTURE PRODUCTS PTY LIMITED Patent Attorney for the Applicant S: PETER MAXWELL ASSOCIATES *a lc---

10 ABSTRACT A decorated laminated product such as a plate is produced by taking a digitally stored image of the decorative material and printing it onto coated paper to form a high definition print which is located beneath a paper surface sheet which is impregnated with a thermosetting resin; a second sheet of paper also impr'gnated with thermosetting resin is positioned below the print and this assembly is then located over material for forming a rigid substrate such as a plate. Heat and pressure is applied to bond the assembly and the process is such that the thermosetting resin provides a transparent protective covering over the print and bonds the print into the product. o b4 r b *ae S:23511C 17.7.96 i I