EP2689938A1 - Method for producing pens in wood casings - Google Patents

Abstract

The method involves providing two coatings end cap in rear end face of a pin. The end face of a primer layer is applied with UV paint. The primer layer is cured with UV light. A color layer is applied by pad printing process. The pencils (1) are fixed on a support (8). The end surfaces (14) are provided on the same height level. The end surfaces of the pencils with a container contacted with available UV coating.

Description

The invention relates to a method for producing wood-filled pins, wherein at least two coatings forming an end cap are applied to the end face of the rear pin end. So far, a dipping method is used for this purpose. In such a method, a number of pins are fixed on a support so that their pin longitudinal directions are parallel to each other and their end faces are arranged at the same height level. The carrier equipped with pins is lowered to a bath with liquid coating agent so far that the end faces come into contact with the coating agent. When removing the pins from the dip forms on the front side a covering this coating.

For procedural economic reasons, the face is not ground smooth before coating. It therefore still has pores and depressions, so a certain roughness. Therefore, a primer layer is first applied to the end face, which covers pores and depressions in the end face and serves as a basis for a subsequently applied color coating. The primer layer is dried, which takes up to 12 hours depending on the thickness of water-based coating compositions. On the dried primer layer finally, also in the dipping process, the color layer is applied. The ink layer is - due to the dipping process - also relatively thick, so that in the case of a water-based coating material for their drying a time required as in the drying of the primer layer is required.

The object of the invention is to provide an alternative method for producing holzgefasster pins, which in particular allows a higher production throughput.

This object is achieved in a method according to claim 1, characterized in that applied to the front side of a primer layer of a UV coating, the primer layer cured with UV light and then a color coat is applied to the primer layer by means of a printing process. This initially results in the advantage that no time-consuming drying is required for the primer. After removing the pins from the primer, a UV cure can take place immediately, taking only milliseconds to seconds. Since a UV varnish does not solidify by drying, ie by evaporation of a solvent, but by a radiation-induced crosslinking, the layer applied to the front side can be comparatively thin, which facilitates the process. For example, there is a risk that such a layer will run or form drops, which would affect the later appearance of the end cap.

Immediately after the curing of the UV varnish - without intermediate storage of the pins and virtually no loss of time - the color layer can be applied. However, this is not done by a dipping process, but by a printing process. By means of a printing process, it is possible to produce color layers with such a thin layer thickness that a solvent bleed even in the case of water-based coating materials dry extremely fast. In addition to saving time, the proposed procedure thus also involves a saving of coating material.

In principle, all printing methods which can be used to produce thin color layers, for example the inkjet printing process or the screen printing process, are suitable as printing processes. However, very particularly preferred is the pad printing. The tampon elements used in this case, elastic pressure media, for example made of silicone rubber, are particularly suitable when the end face of the pins is not flat but convex or convex.

In particular, with the pad printing method, it is possible in a simple manner, a group of pens, which are fixed to a serving for diving, approximately plate or disk-shaped carrier, in this arrangement, so without further manipulation to print. For this purpose, the equipped with pins carriers must be passed only to a printing station. In this case, each individual pin or a group of pins can be contacted or acted upon, each with a tampon element. This is particularly easy to accomplish if the pins are arranged at right angles to each other extending longitudinal and transverse rows.

• Fig. 1 das hintere Ende eines holzgefassten Stiftes mit einer Endkappe,
• Fig. 2 einen Querschnitt entsprechend Linie II - II in Fig. 1,
• Fig. 3 eine perspektivische Darstellung, welche einen Tauchvorgang zur Erzeugung einer Grundierung auf der hinteren Stirnfläche eines Stiftes verdeutlicht,
• Fig. 4 eine perspektivische Darstellung, die das Bedrucken der mit einer Grundierung versehenen Stirnfläche mit Hilfe eines Tamponelemente aufweisenden Druckstempels zeigt,
• Fig. 5 einen gegenüber Fig. 4 anders gestalteten Druckstempel.

The invention will now be explained in more detail with reference to the accompanying drawings. Show it:

• Fig. 1 the back end of a wood-filled pin with an end cap,
• Fig. 2 a cross section corresponding to line II - II in Fig. 1 .
• Fig. 3 a perspective view illustrating a dipping process for producing a primer on the rear end face of a pin,
• Fig. 4 a perspective view showing the printing of the provided with a primer face with the aid of a tampon having plunger,
• Fig. 5 one opposite Fig. 4 differently designed plunger.

A wood-cased pin 1 consists essentially of a shaft 2 made of wood and a centrally fixed in the shaft 3 mine. The front end of the pin 1 is conical or provided for such a design. An end face 4 arranged at the rear end of the pin extends in a plane or is, as in Fig. 1 and 2 shown convex or convex. The mine 3 extends into the end face 4. The end face 4 is covered by an end cap 5, which preferably consists of a base layer 6 and a covering this color layer 7.

In the manufacture of the end cap 5, the procedure is as follows:

In a, for example, plate-shaped carrier 8, a number of pins 1 are arranged so that their longitudinal directions 9 extend parallel to each other and the end faces 4 are at the same height level 10. To fix the pin 1 fixing holes 13 are provided in the carrier, in which the pins 1 are inserted with its front end (14). The carrier 8, which is held for example movable on a rail 11, is positioned so that the end faces 4 downwards. To produce the primer layer 6, a container 15 is provided, in which a UV varnish 16 is in liquid form. The carrier 8 and the container 15 are moved relative to one another such that the end faces 4 touch the surface of the liquid UV varnish 16, wherein a layer or a film of the UV varnish adheres to the end faces 14. Following this, the carrier 8 is transferred to a UV irradiation station (not shown). After a brief UV irradiation, the UV varnish has hardened. As a UV varnish, for example, a preparation having the following composition can be used: Oligomer (Sartomer CN2282, Cray Vally) 66% Monomer (Laromer TPGDA, BASF) 30% Photoinitiator (Darocur 1173, BASF) 2.4% Photoinitiator (Irgacure 819, BASF). 1.2% Defoamer (Tego Airex 900, Evonik) 0.2% Surfactant (Tego Rad 2600, Evonik) 0.2%

After UV irradiation of a few seconds, the primer layer 6 is cured and can now be printed by means of a printing process, with which thin layers of paint can be produced. In the preferred printing method, a tampon printing method, a plate-shaped plunger 17 is used with a flat side on which at least one pad element 18 is present. In the case of a single tampon element 18 this is dimensioned in the width and longitudinal direction so that the total number of supported by the carrier 8 pins 8 contacted and an existing on the tampon element 18 color preparation can be transferred to the end faces 4 of the pins 1. At the in Fig. 4 illustrated embodiment Each pen is associated with a tampon element 18. The pins are arranged in a regular grid, forming longitudinal rows 19 and transverse rows 20. In the same grid, the tampon elements are arranged on the plunger 17. The in Fig. 5 shown plunger 17 has strip-shaped tampon elements 18 ', which each print a pin longitudinal row 19 of a fixed in a carrier 8 group of pins 1.

For the color layer, for example, a water-based color coat with the following composition is suitable: Binder: Aqueous polyurethane dispersion (Liopur 97-282, Synthopol-Chemie) 50.6% Polyurethane thickener (Rheolate 244, Elementis) 3% Aqueous pigment preparation (Levanyl Blue G-LF, Bayer AG) 0.7% Aqueous pigment preparation (Levanox white RNZ-SF, Bayer AG) 5% Solvent: 1,2-propanediol 10% Defoamer (EFKA 2526, EFKA Additives BV) 0.7%. Water ad 100%

The plunger 17, after a printing operation has been carried out in the manner described, loaded again with color paint, for example, by being pressed onto a pad soaked with the paint.

Claims (6)

Method for producing wood-clad pins (1), in which the rear end face (14) of the pin is provided with an end cap (5) consisting of at least two coatings, characterized in that a primer layer (6) of a UV varnish is applied to the end face (16), the primer layer is cured with UV light and then a color layer (7) is applied to the primer layer by means of a printing process. A method according to claim 1, characterized in that the color layer (7) is applied by a tampon printing method. A method according to claim 2, characterized in that the pins (1) on a support (8) are fixed so that they are parallel to each other and their end faces (14) at the same height level (10) are arranged, wherein the end faces (14 ) of the pins with a in a container (15) existing UV varnish (16) are contacted. A method according to claim 3, characterized in that with unchanged fixation of the pins (1) in the carrier (8) and after UV irradiation of the primer layer (6) on the color layer (7) are contacted with a tampon printing element. A method according to claim 4, characterized in that each pin (1) or a group of pins are contacted with a tampon printing element (18). A method according to claim 4 or 5, characterized in that the pins (1) in mutually perpendicular longitudinal and transverse rows (19, 20) are arranged.

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