Digital printing and embossing

Abstract

A method and equipment to form a digital print by applying dry colourants on a surface, bonding a part of the colourants with a binder and removing the non-bonded colourants from the surface. Also, a method to form embossed structures. Hard press particles may be applied in patterns on a carrier that is pressed against a surface.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application claims the benefit of U.S. Provisional Application No. 61 / 751,418, filed on Jan. 11, 2013. The entire contents of U.S. Provisional Application No. 61 / 751,418 are hereby incorporated herein by reference in their entirety.TECHNICAL FIELD[0002]The disclosure generally relates to the field of digitally created decorative surfaces for building panels such as floor and wall panels. The disclosure relates to powder based colourants and hard particles that may be used to create decors and structures on such surfaces.FIELD OF APPLICATION[0003]Embodiments of the present invention are particularly suitable for use in floors, which are formed of floor panels comprising a core or a body, a decorative layer and preferably a transparent wear resistant structured layer above the decorative layer. Preferred embodiments are conventional laminate floors, powder based floor, wood floors, plastic based LVT floors and ceramic tiles. The...

AI Technical Summary

Benefits of technology

The invention provides a method and equipment for printing digital patterns on surfaces using dry ink and liquid ink. The method involves applying colorants to a surface, bonding them with a binder, and then removing non-bonded colorants to form the desired pattern. The invention offers improved cost efficiency and productivity compared to conventional digital printing methods. The invention also provides a method for creating embossed surfaces with deep patterns using a combination of digital printing and heating print heads. The invention uses pigments and resins that are cost-effective and reliable. The invention also allows for the use of thermosetting resin as a binder, which is exposed to increased temperature after application. The invention also provides a dry ink composition with macro colorant particles for bonding to a liquid print. Overall, the invention offers a more efficient and cost-effective way to print digital patterns on surfaces.

Problems solved by technology

The disadvantage is that they are less transparent and the decorative pattern is covered by a grey layer that disturbs the printed pattern.

The production process is rather complicated and is only cost efficient in very large production volumes.

It is more difficult to create designs such as for example wood decors.

The penetration is however rather limited since the ink drops will be bonded to the first particle that they hit, mainly the wood fibres.

Additional circumstances that that have contribute to the introduction of the digital printing technology in the tile industry is the fact that ceramic tiles are rather small compared to for example laminate and powder based floors that are produced as large pressed boards of about 2.1*2.7 m. Rather small printers with limited number of print heads may be used in the tile industry and the initial investment is rather limited.

However the volumes are still very small, especially in wood and laminate flooring applications, mainly due to high cost of the ink and high investment cost for the industrial printers.

The flexibility that the digital printing technology provides is limited by the embossing that is fixed and not possible to adapt to the variations of the digitally printed décor.

Such printers are slow but one small print head can generate a bigger image.

However a part print is not as flexible as a full print since the base colours are more difficult to change than when a full print is used.

Thermal technology imposes the limitation that the ink must be heat-resistant, generally up to 300° C. because the firing process is heat-based.

This makes it very difficult to produce pigment based multi colour thermal heads.

A main problem for all types of inks and print heads is that when ink dries by evaporation it may dry up and clog the nozzles.

This is difficult particularly at the rather low viscosities, which are required for a good functioning of the print heads.

Pigments have a natural tendency to settle out and fall down in the liquid carrier.

The inclusion of resins that serve as binder in the ink composition limits the possible amount of pigments, as both components increases the ink viscosity.

Colour pigments as raw materials are rather cost competitive especially as rather large particles of about one micron but the production of pigment based inks comprising very small particles and other inks for digital printers is very complicated and expensive and this results in a very high cost for the ink that normally may be in the region of about 50-100 EUR / litre.

This means that digital printing based on conventional pigment based liquid ink is only cost competitive in small series when very high production flexibility is required.

3D printers have a very low productivity and construction of even small objects can take several hours.

However, the method has many disadvantages.

The major disadvantages are related to high cost for the paper or transfer film and the colour limitations to mainly one colour.

Digital printing is a very flexible method that may provide a high quality print but it cannot be fully utilized in industrial application and especially not in floorings due to the high cost for the ink, problems related to drying and clogging of nozzles, especially when pigment based inks are used and the need for special protective layers that are costly and not completely transparent.

The high ink costs are primarily caused by the need to mill down the colour pigments to well-defined very small particles and to disperse the particles throughout the carrier fluid.

One specific problem related to laminate flooring is the fact that the printed-paper swells and shrinks in an uncontrolled way during impregnation and the size of the décor may vary between different impregnate paper sheets.

The flexibility of digital printing is also limited in connection with EIR surfaces since the printed décor must always be adapted to the embossed matrix.

A common feature for all such floors as described above is that all surfaces in a production batch have the same basic structure and are not possible to adjust and adapt to any changes in the décor.

This method is not suitable for floor applications.

Thicknesses of at least 100-200 micron that are required to form an embossing in laminate and 200-700 micron to match the requirement of powder based floors are not possible to produce in an economic way.

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