System and method for applying adhesive using a digital inkjet print head

Abstract

To provide a system and method for applying adhesives by a digital inkjet print head for bonding at least one first element and at least one second element.SOLUTION: A system comprises: a processing unit that is functionally connected to a digital inkjet print head 4, and has a data set about physical features of at least one of elements 2, 3 to be bonded which are different in different areas. The processing unit sets an amount of adhesive per unit area and / or select a type of the adhesive in both elements 2, 3 for excellent adhesion between the elements 2, 3 according to the data about the physical features such that the amount per unit area or the type of adhesive deposited on a surface of at least one of the elements to be bonded is different in different areas on the surface of the at least one of the elements to be bonded.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The subject of the present invention is a system and method for applying an adhesive by a digital inkjet head in order to bond together at least two elements, such as panels or profile materials and foils or sheets.

Background Art

[0002] An adhesive or sticky substance has the function of bonding and attaching two base materials, for example bonding and attaching a base material to a covering material or another layer.

[0003] The adhesive is solid when bonding, but in order to apply, move, stretch, etc. the adhesive on the surface to be bonded, and even when the adhesive is applied to the element to be bonded, the adhesive needs to have a specific fluidity in order to surely spread widely over the surface of the element.

[0004] Depending on how the adhesive turns into a liquid, there are various types of adhesives. - Cold glue to which a solvent or diluent is added to turn it into a liquid - Hot glue or hot melt adhesive that melts with heat and becomes a liquid

[0005] Regarding the physical bonding process, bonding can be defined as the force that can bind molecules of materials with different properties. On the other hand, the cohesive force is used to refer to the attractive force between molecules of the same material. In an application for bonding two elements where an appropriate adhesive that provides good bonding is selected, in principle, the maximum strength of the bonding is obtained with the thickness of the adhesive layer suitable for filling the depressions present on the surface due to the roughness and pores of the surface of the element to be bonded.

[0006] A thickness of adhesive layer exceeding the minimum thickness mentioned above results in a lower resistance bond. This is due to the internal cohesive force of the adhesive. Generally, if the adhesive used for bonding the materials has good adhesion, this adhesion is always greater than the internal cohesive force of the adhesive itself. Therefore, the amount of adhesive adjusted to the surface roughness is the amount that yields the strongest bond.

[0007] Currently, the most common method for applying adhesive is as follows: - The use of rollers, which involves applying the adhesive by an application roller to which the adhesive has been added by an addition roller. - The application lip involves adding adhesive through a slot, and the amount of adhesive applied can be changed by altering the speed at which the adhesive passes through it.

[0008] Additionally, although relatively few in number, certain types of adhesives are applied using spray guns, swirl nozzles, or various spray systems.

[0009] Since coating methods using rollers or lips are contact methods, they have the disadvantage that if the surface to which the product is applied is contaminated, the rollers or lips will also become contaminated, damaged, and worn down (for example, by abrasion).

[0010] Because it is a contact method, it also has the disadvantage that application can be difficult or even impossible if the surface to be coated is not perfectly smooth, has irregularities, or is complex.

[0011] Furthermore, some adhesive materials cannot bond through contact because their own composition may cause them to peel off in parts.

[0012] Generally, all conventional coating methods share the common characteristic that the weight per unit area, that is, the amount of product that can be coated per unit area, is uniform and within a certain tolerance range. [Overview of the project] [Problems that the invention aims to solve]

[0013] The system and method of the present invention consist of applying an adhesive, which was previously applied by the conventional method described above, using a print head for digital inkjet technology. [Means for solving the problem]

[0014] The system for applying adhesive by a digital inkjet print head of the present invention is applicable to bonding at least one first element and at least one second element. The system includes at least one digital inkjet print head. It further includes a processing unit functionally connected to the digital inkjet print head. The processing unit includes a dataset relating to the physical characteristics of at least one of the elements to be bonded, the physical characteristics of which differ in different regions of the at least one of the elements to be bonded. The processing unit is configured as follows: - Based on data regarding its physical characteristics, the amount and / or type of adhesive applied per unit area to at least one surface of the elements to be bonded is set. As a result, the amount or type of adhesive applied per unit area to the surface of at least one of the elements to be bonded differs in different areas of the surface of the elements to be bonded. - The digital inkjet print head is controlled to release the amount and / or type of adhesive per unit area onto the surface of at least one of the elements to be bonded.

[0015] As described above, the present invention is characterized in that the amount of adhesive ink or type of adhesive applied per unit area differs in different areas of the coated surface of the element to be bonded. Therefore, the present invention makes it possible to set or select different amounts or types of adhesive per unit area in a controlled manner according to the physical characteristics of the element to be bonded.

[0016] As described above, the present invention makes it possible to apply adhesive to specific areas of a surface. This makes it possible to apply different amounts of adhesive to the surface as needed in each area, and even to precisely apply adhesive to complex surfaces, curved surfaces, and vertical or inclined areas such as edges.

[0017] Therefore, the present invention makes it possible to adhere an adhesive according to the following physical characteristics of the elements to be bonded. - Surface texture, such as wood grain, cracks, and the presence of surface defects. - The material of the elements being bonded. This can affect the surface roughness / porosity, and therefore the wettability and adhesion or curing of the adhesive. - The shape of the elements to be bonded or the inclination of the surface to which the adhesive is applied. For example, application to the sides or edges and front of a panel.

[0018] According to the above, the data relating to the physical characteristics of the elements to be bonded includes at least one of the data relating to the surface roughness, the morphology of the surface, and / or the type of material of the elements.

[0019] The ink ejection head, or inkjet head, enables the ejection of the product according to the physical and chemical properties of the adhesive described above. Some of the most representative properties are as follows: -viscosity - Particle size -surface tension -conductivity

[0020] Inkjet-based adhesive application offers significant advantages because it allows for very precise application of adhesives at extremely low concentrations; however, conventional systems have certain limitations in achieving such low concentrations. Therefore, as mentioned above, in addition to savings through reduced unnecessary adhesive consumption, better adhesion is achieved.

[0021] Another object of the present invention is a method of applying an adhesive by a digital inkjet printing head to adhere at least one first element and at least one second element. As described above, the system of the present invention includes at least one digital inkjet printing head. The method of the present invention includes the following steps. - A step of receiving data regarding at least one physical characteristic of at least one of the elements to be adhered by a processing device functionally connected to the digital inkjet printing head. Here, the physical characteristic varies in different regions of at least one of the elements to be adhered. - A step of setting the amount per unit area of the adhesive to be adhered to the surface and / or selecting the type of the adhesive according to the data regarding the physical characteristic of at least one surface of at least one of the elements to be adhered in the processing device. The amount per unit area or the type of the adhesive adhered to the surface of at least one of the elements to be adhered is made to vary in different regions of the surface of the element to be adhered. - A step of discharging the amount per unit area of the adhesive received from the processing device and / or the type of the adhesive onto at least one surface of at least one of the elements to be adhered by at least one digital inkjet printing head.

[0022] The present invention provides an adhesive by the above injection head and brings, among other things, the following advantages. - It has an accurate amount per unit area on the order of picoliters according to the resolution of the coating head. - Adjust the amount per unit area according to the region and necessity even at the microscopic level. - Adapt the adhesion to the strictly necessary area of the element to be adhered. - Apply different types of adhesives according to different requirements according to the region. - Since there is no contact, the coating system allows a certain degree of unevenness on the coating surface. - Enable the application of adhesives on surfaces that are difficult or impossible to contact, such as curved, vertical, inclined, uneven surfaces, etc., or surfaces where particles peel off when contacted. - In the manufacturing of hygiene products such as diapers, sanitary napkins, bandages, and adhesive plasters, this prevents contamination through contact with the application head. - The coating system enables the creation of a highly sealed supply circuit, which allows for the application of adhesives, such as cyanoacrylate adhesives, regardless of their high reactivity.

[0023] In the exemplary embodiment, the processing apparatus includes a digital pattern of at least one of the elements to be bonded, and each region of the digital pattern is associated with the amount or type of adhesive applied per unit area.

[0024] In another exemplary embodiment, the coating system includes a sensor connected to the processing unit for measuring the physical characteristics of at least one of the elements to be bonded and transmitting the measurement to the processing unit.

[0025] The application areas of the present invention will correspond to use in panel lamination processes, i.e., flake bonding to flat surfaces, and in profile material coating processes, i.e., flake bonding to inclined surfaces involving flake forming. These correspond to surface finishing processes for panels and profile materials, usually made of wood or its derivatives, aluminum, PVC, etc., using adhesives.

[0026] Another application is the bonding and adhesion of multiple layers of different thermal insulation materials, which may have different types of elements as materials than those described above.

[0027] The present invention can also be applied to the indexing of different parts of various materials such as plastic, metal, wood, and cellulose, to obtain excellent structures formed by these different parts, for example, in the formation of doors, composite profile materials, and in the manufacture of diapers, sanitary napkins, bandages, adhesive plasters, etc. [Brief explanation of the drawing]

[0028] Figures are provided to complete the explanation and to provide a better understanding of the present invention. These figures form an integral part of the explanation and illustrate exemplary embodiments of the present invention. [Figure 1] This shows a cross-sectional view of a laminated panel. [Figure 2] A schematic diagram of an exemplary embodiment is shown, in which adhesive is applied to the two elements to be bonded, specifically the thin slice and the substrate, to perform lamination or coating. [Figure 3] A schematic diagram of an exemplary embodiment is shown, in which adhesive is applied to one of the two elements to be bonded, specifically a thin slice, for lamination or coating. [Figure 4] A schematic diagram of an exemplary embodiment is shown, in which a water-based or solvent-based adhesive is applied to the elements to be bonded, specifically the flakes and substrate, for lamination or coating. [Figure 5] A schematic diagram of an exemplary embodiment is shown, in which one of the elements to be bonded, specifically the substrate, is coated with a water-based or solvent-based adhesive for lamination or coating. [Figure 6] A schematic diagram shows an example embodiment of an application where an adhesive is applied to the substrate and indexing is performed on each sheet. [Modes for carrying out the invention]

[0029] Figure 1 shows a laminated panel containing two elements (2, 3) consisting of a substrate and a sheet bonded together with adhesive (1). Adhesive (1) creates an aggregated region between both elements (2, 3), and an adhesive region between the substrate and the sheet is created around adhesive (1). The thicker the layer of adhesive (1), the larger the aggregated region, resulting in poorer adhesion between both elements (2, 3).

[0030] In panel or profile materials made of materials such as MDF, HDF, and chipboard, which are commonly used in lamination or coating, the manufacturing process (e.g., fiber orientation) results in substantially larger surfaces (e.g., top or bottom) being much smoother than smaller surfaces (e.g., edges). Therefore, typically, more adhesive must be applied to bond the coating to the smaller surface than to the larger surface. Figure 1 shows details of a laminated panel where the edge has greater roughness than the top surface, and the edge requires more adhesive (1).

[0031] In the method and system of the present invention, a first element (2) consisting of continuous thin sheets supplied from a coil, i.e., continuous thin sheets of material, or discontinuous thin sheets of different materials such as paper, PVC, HPL, CPL, etc., can be used. This allows the second element (3), such as a panel or profile material, to have any desired appearance according to the covering design used.

[0032] Figures 2 to 6 illustrate different applications of the present invention, in which the adhesive (1) can be applied to one or both of the elements to be bonded (2, 3) by a digital inkjet print head (4) functionally connected to a processing device. After application and subsequent curing or drying, one element (2) is attached to the other element (3), and bonding is achieved by applying pressure using a continuous coating or lamination method.

[0033] In the application example shown in Figure 2, the adhesive (1) is applied by digital inkjet printing to the two elements to be bonded (2, 3), specifically a continuous flake and a substrate. The continuous flake is supplied from a supply coil (10) and guided by a guide roller (20) until it is attached to the substrate surface by a pressure roller (30). The adhesive (1) is cured after being applied to both the continuous flake and the substrate. The adhesive (1) is cured by, for example, electromagnetic radiation (40), UV, IR, or an electron lamp.

[0034] In the application example shown in Figure 3, unlike the application example shown in Figure 2, the adhesive (1) is applied by digital inkjet printing to only one of the two elements (2, 3) to be bonded, specifically, to a continuous thin sheet.

[0035] In the application example shown in Figure 4, unlike the exemplary embodiments shown in Figures 2 or 3, a water-based or solvent-based low-temperature adhesive (1) is applied to the two elements to be bonded (2, 3), specifically a continuous flake and a substrate, by digital inkjet printing. After the adhesive (1) is applied to both the continuous flake and the substrate, it is fixed by drying. The adhesive (1) is dried by evaporation of water or solvent, by passing through a heating chamber (50) equipped with a heating means such as hot air or a heating lamp (e.g., IR).

[0036] In the application example shown in Figure 5, unlike the exemplary embodiment shown in Figure 4, a water-based or solvent-based low-temperature adhesive (1) is applied to one of the elements to be bonded (2, 3), specifically, for example, to the substrate.

[0037] In the application example shown in Figure 6, discontinuous flakes are used, unlike the exemplary embodiments shown in Figures 1 to 5. The flakes are supplied sheet by sheet from a stack of flakes (60) until they are attached to the substrate by a pressure roller (30).

[0038] In the exemplary embodiment, the processing apparatus includes a digital pattern on at least one surface of the elements (2, 3) to be bonded. Different areas of the digital pattern are associated with one amount or one type of adhesive (1) per unit area to be applied.

[0039] The amount of adhesive per unit area, or the variable amount of adhesive, can be adjusted to match the decorative design of the elements (2, 3) being bonded. In other words, it can be adapted to the decorative design.

[0040] For example, the system of the present invention includes a scanner (5) functionally connected to a processing device and configured to scan at least one surface of the elements (2, 3) to be bonded and to transmit the scan data to the processing device in order to create a digital pattern.

[0041] In certain applications of sheets or coverings, so-called embossed flakes, two-dimensional flakes, or textured flakes are used. In these cases, applying adhesive (1) with conventional lip or rollers is cumbersome and inefficient. The complexity of the application lies in the fact that these flakes have a structure on the design side, while the adhesive (1) application side also has an opposite structure on the "visible" side, which is not perfectly flat.

[0042] Therefore, in order to bond them together, the usual practice is to apply adhesive to the entire surface and then excessively press the applicator lip or roller to fill any recessed areas with adhesive. Consequently, a large amount of adhesive is consumed.

[0043] According to the present invention, a thin sheet design is scanned or a digital pattern is provided as a digital file, and by processing the digital scan / file, a digital inkjet print head (4) ejects the required amount of adhesive (1) to each point.

[0044] In another exemplary embodiment, the application of adhesive (1) can be performed dynamically, as the application system in the production line includes sensors that measure the characteristics of the elements (2, 3) to be bonded and set the amount of adhesive to be applied to different areas. The measurement of at least one of the physical characteristics is sent to the processing unit. [Explanation of symbols]

[0045] 1. Adhesive 2. Elements to be bonded 3. Elements to be bonded 4. Digital inkjet print head 5 Scanners 10 supply coils 20 Guide rollers 30 Pressure Rollers 40 Electromagnetic radiation 50 Heating chamber 60 thin slices stack

Claims

1. A system for applying an adhesive (1) by a digital inkjet print head (4) to bond at least one first element (2) and at least one second element (3), the system comprising a processing unit functionally connected to the digital inkjet print head (4), the processing unit comprising a dataset relating to the physical characteristics of the first element (2) and the second element (3) to be bonded, wherein the physical characteristics differ in different regions of at least one of the elements (2, 3) to be bonded, and the processing unit - The amount or type of adhesive (1) per unit area applied to the surface of at least one of the elements (2, 3) to be bonded differs in different regions on at least one of the surfaces of the elements (2, 3) to be bonded, and the amount of adhesive (1) per unit area applied to the surface of at least one of the elements (2, 3) to be bonded is set and / or the type of adhesive (1) is selected in accordance with the data relating to the physical characteristics of the first element (2) and the second element (3) to be bonded, in order to ensure good adhesion between the elements (2, 3). - Control the digital inkjet print head (4) to release the amount per unit area and / or type of adhesive (1) onto at least one surface of the elements (2, 3) to be bonded. A system for applying an adhesive (1) using a digital inkjet print head (4), characterized in that it is configured in such a way.

2. The apparatus comprises a digital pattern on at least one surface of the elements (2, 3) to be bonded, wherein different regions of the digital pattern are associated with one amount or one type of adhesive (1) per unit area to be applied, characterized in that a system for applying adhesive (1) by a digital inkjet print head (4) according to claim 1.

3. The system for applying adhesive (1) by a digital inkjet print head (4) according to claim 2, characterized in that the system includes a scanner (5) functionally connected to the processing device and configured to scan at least one surface of the elements (2, 3) to be bonded and to transmit the scan data to the processing device to create the digital pattern.

4. A system for applying an adhesive (1) by a digital inkjet print head (4) according to any one of claims 1 to 3, wherein the system includes a sensor connected to the processing device, the sensor being configured to measure at least one physical characteristic of at least one of the elements (2, 3) to be bonded and to transmit the measurement value to the processing device.

5. A system for applying an adhesive (1) by a digital inkjet print head (4) according to any one of claims 1 to 4, characterized in that the data relating to the physical characteristics of both elements (2, 3) to be bonded includes at least one of data relating to the surface roughness, the surface morphology, and / or the type of material of the elements.

6. A method for applying an adhesive (1) by a digital inkjet print head (4) to bond at least one first element (2) and at least one second element (3), wherein the system comprises at least one of the digital inkjet print heads (4), and the method is - A processing device functionally connected to the digital inkjet print head (4) receives data relating to the physical characteristics of the first element (2) and the second element (3) to be bonded, wherein the physical characteristics differ in different regions of at least one of the elements (2, 3) to be bonded. - The steps of using the apparatus to set and / or select the amount or type of adhesive (1) in the region between both elements (2, 3) for good adhesion between the elements (2, 3), to be applied to the surface of at least one of the elements (2, 3) to be bonded, such that the amount or type of adhesive (1) applied per unit area to the surface of at least one of the elements (2, 3) to be bonded differs in different regions on the surface of at least one of the elements (2, 3) to be bonded, - A step of dispensing the amount per unit area and / or type of adhesive (1) received from the processing apparatus onto at least one surface of the elements (2, 3) to be bonded by at least one of the digital inkjet print heads (4); A method characterized by including the following.

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