EP2110185B1 - Method for creating embossed structures of the surface of a pen - Google Patents

Description

The invention relates to a method for producing raised structures on the surface of a pin. Under a pen here is a writing-cosmetic pencil o. The like. Understand. Such pins have a shaft made of wood or plastic. In order to improve the handling of the pin, in particular the retention of the pin during its use, raised structures are applied from a non-slip material on the pin or shaft surface. The material is flowable in the initial state and solidifies after application. In particular, in the production of a pattern formed by a plurality of relatively small structures, such as a pebble pattern, to achieve an accurate appearance it is necessary for all the structures to have exactly the same outline shape, height and contour. To ensure this, a material is required that has only a slight tendency to bleed after application to the pin surface and solidifies as quickly as possible. Thus, the requirements for the material are not yet exhausted. So that it allows a fatigue-free handling of the pen, it must also be handy in the case of sweaty hands and have a pleasant feel. In addition, it must adhere to sticks, which are made of a variety of materials, such as those made of plastics such as ABS, PP and PS or unpainted or painted wood. An important aspect of the suitability of a material for sublime structures is, after all, still its processability. The best material for haptics, surface adhesion and grip is useless if it can only be processed poorly in a manufacturing process trimmed to the lowest possible cost and the accurate appearance of raised structures required for successful marketing can not be achieved.

Out EP 1 177 108 For example, a wood-filled pencil is known, the raised structures of which are made by applying an aqueous, water-hardening polymer dispersion or a mixture of such dispersions. Pens coated with such material must be stored in dry rooms for up to two days after application. Accordingly, in order to accommodate the ongoing production of two days, large drying rooms are required, which is associated with high operating costs. The long drying time results from the slow evaporation rate of the water of the aqueous polymer dispersions, the high layer thickness and the skin formation occurring during drying. The raised structures obtained by this procedure may in themselves serve their purpose, but their manufacture is laborious and accordingly expensive.

A drying step is also at an example of EP 1 514 700 A2 known processes using systems containing organic solvents for the raised structures. Drying is faster here than with aqueous systems. Apart from the technical effort to avoid a workload with solvent vapors, the volatility of the solvent prepares manufacturing problems. For example, there is a risk that the functionality of application equipment is affected by drying material. Especially when relatively large protruding nubs are to be produced from the pin surface, nozzles are particularly suitable for this because it allows large amounts of material to be applied. If, however, the outlet openings of the nozzles narrow due to the drying up of nubs, this influences the size and shape of the nubs, and thus the desired appearance of a nub pattern. To prevent this, it may be necessary to interrupt the manufacturing process to clean the applicators.

In EP 1 514 700 A2 Also, a method is described in which a radiation-curing solvent-free plastic preparation is applied by screen printing on the surface of wood pencils. Thereafter, the pins are immediately subjected to UV irradiation, which occurs almost immediately hardening of the applied structures. With the screen printing method, the amount of material to be applied to one point of the pin surface is limited, so that handle nubs of greater height, ie handle nubs, which protrude relatively far from the pin surface, can not be produced. For this purpose, nozzles are more suitable.

Attempts to produce nipples using such preparations with the aid of nozzles, it was found that when applying such drops of material with nozzles came to a thread train. This caused the shape of the pimples to become irregular. In addition, there was some contamination of the pin surface and the nozzles by adhering thread parts. In addition, it was found that the deposited material drops showed a strong tendency to bleed, which Among other things, leads to an irregular unclean appearance of the applied pimple pattern.

The object of the invention is to propose a method for producing raised, serving as Griffnoppen structures on the surface of a pen, which can be easily performed in procedural perspective and in particular for generating clearly from the pin surface protruding handle knobs, especially on plastic pins or - shops suitable.

This object is achieved by a method according to claim 1. Thereafter, using a nozzle, a flowable plastic preparation is applied, which consists of 40% to 98% of a radiation-curable plastic composition formed from oligomer and monomer, 0.1% to 30% of a photoinitiator system, 0.3% to 30% amorphous silica and / or micronized amide wax, 0% to 59% colorant, 0% to 60% filler and 0% to 10% of other additives. The reactive monomer diluent contained in the plastic preparation dilutes the oligomer, and thus acts as an organic solvent. Unlike this, however, it combines chemically with the oligomer, so that it can not - as is the case with organic solvents - be removed by a drying process. The amorphous silicon dioxide is preferably flocked aggregates of SiO 2 particles produced in the flame. Micronized amide waxes are preferably waxes whose primary particles have a particle size of 5 μm to 30 μm.

It was completely surprising that in the type of application in question, the production-related disadvantages described above could be circumvented, in which case the decisive factor is the presence of an amorphous silicon dioxide and / or a micronized amide wax in the preparation.

In a manufacturing process carried out in the manner according to the invention, the preparation discharged from the nozzle runs extremely uniformly to form a smooth drop surface, but does not continue to run and widen uncontrollably, resulting in a nub pattern of very uniformly shaped nubs. When the nozzle is removed from a drop of the plastic preparation applied to the pin surface, it separates from the preparation, without resulting in a threadline, ie the formation of a thinning with increasing distance of the nozzle and finally tearing material thread. If such threads pollute the pin surface, the pin must be rejected as scrap. The threads would also pollute the nozzles, which would mean a corresponding cleaning effort and downtime during production.

Due to the rapid curing after exposure, in particular with UV radiation, a separate drying room is no longer necessary. The pins are practically not thermally stressed, so that pins with temperature-sensitive shafts and / or mines can be processed Furthermore, radiation-curing compositions have the great advantage that no drying can be done on tools, unless exposed to UV light. If deposits occur after longer process times on tools and devices, they can be removed purely mechanically.

It is furthermore advantageous in the case of the proposed compositions that, owing to the absence of water, corrosion of device constituents which come into contact with a preparation is not to be feared.

Finally, it is advantageous that, in the absence of an organic solvent, an increase in the viscosity of the preparation during the production process due to evaporation of the solvent is excluded.

Good results in terms of processability, grip and adhesion are achieved with preparations containing as radiation-curable plastic composition at least one acrylate oligomer in a proportion of 70% to 80% and at least one acrylate monomer in a proportion of 1% to 25% and a photoinitiator system with a share of 1% to 8%. Suitable acrylate oligomers are, in particular, those from the group consisting of aromatic and aliphatic epoxy acrylates, polyester, polyurethane, oligoether and amine-modified oligoether polyol acrylates.

However, best results are achieved with formulations containing 70% to 80% urethane acrylate oligomer and 1% to 15% acrylate monomer, and preferably 0.5% to 5% amorphous silica and / or micronized amide wax. In all cases, the photoinitiator system is preferably composed of 0.5% to 5% of a photoinitiator and 0.5% to 3% of a co-initiator together. The processability of the preparation can be improved by the addition of a leveling agent and lubricant in a proportion of 0.3% to 2% and a defoamer in a proportion of 0.1% to 1%. In particular, the said components have a favorable effect in terms of a smooth surface of the handle nubs.

In a stick made in the manner described above, the plasticizer formulation may contain a filler, preferably selected from the group consisting of kaolin, talc, barium sulfate, titanium white, calcium carbonate and mica. In order to influence the tactile properties of the surfaces of the raised structures, fillers from the group of aluminum silicate hollow spheres, expanded hollow spheres, polyurethane soft-feel pellets, micronized plastics such as polypropylene or PTFE, and PE waxes are particularly suitable.

The adhesion of the plastic preparation to different plastics, such as ABS, PS or PP, can optionally be improved by pretreatment of the plastic surfaces. For example, Flaming, corona treatment and plasma treatment.

• Fig. 1 zwei Kunststoffschäfte mit Griffnoppen,
• Fig. 2 eine Auftragsvorrichtung.

The invention will now be explained in more detail with reference to the accompanying drawings and some examples of plastic preparations. Show it:

• Fig. 1 two plastic shafts with grip nubs,
• Fig. 2 an applicator.

The figure shows two plastic shafts 1 having a trigonal outline shape, on the surface of which rows of handle nubs 2 are secured by means of a device of FIG Fig. 2 shown type have been applied. The handle knobs protrude from the surface substantially radially with a height of up to 0.6 mm. Their width or diameter is about 2 mm. Instead of nubs other structures may be applied to the surface of the plastic shaft, for example, extending in the pen longitudinal strip-shaped, punctiform or any other structures. The raised structures or nubs can be applied to both an untreated plastic surface and provided with a paint coating. The plastic shafts are used for example for the production of mechanical pencils, such as mechanical pencils and the like. In addition to the mentioned plastic shafts, of course, surfaces of wooden pencils can be provided with raised structures.

The raised structures - in the following, for reasons of simplification, are referred to as grip nubs - are applied by means of nozzles 3 to the respective surfaces which are part of an application device 4. For the production of in Fig. 1 shown handle knobs with circular outline shape nozzles 3 are used with a circular opening cross section 5. The nozzles 3 are arranged according to the desired nub pattern on a nozzle carrier 6, in the present case in a row of two. Within the nozzle carrier 6, a cavity 7 is provided, with which the nozzles 3 are in fluid communication and which is fed via a central feed channel (not shown) with a plastic preparation. In order to achieve the most equal possible distribution of the flow of material to the nozzles 3, is within the cavity. 7 a corresponding device 8 available. For constructive details is on the patent DE 101 03 375 C1 directed. With a device of in Fig. 2 shown type can be produced in a simple manner practically with a single shot a plurality of equal sized handle nubs. But problematic is the removal of the nozzles 3 after the delivery of the plastic preparation on the surface of pins or Stiftschäften and the running of the preparation between the order time and the irradiation with a curing of the plastic mass causing radiation.

Some example formulations which avoid the mentioned effects are given below. The percentages in these examples relate to the plastic mass in the flowable, that is not yet hardened initial state. All percentages are by weight unless otherwise specified.

Example 1:

UV-curable plastic preparations for transparent or colorless handle knobs with a diameter of 2 mm and a height of 0.5 mm for plastic shanks. Formulation examples A and B are comparative examples, they contain neither amorphous silicon dioxide nor micronized amide wax. raw material function A B C Roskydal UA VP LS 2258 (Bayer Material Science) Aliphatic urethane acrylate, oligomer 77.3% 57.3% 57.3% Roskydal UA XP 2491 (Bayer Material Science) Aliphatic urethane acrylate, oligomer 20% 20% 20% Laromer TPGDA (BASF) Tripropylene glycol triacrylate, reactive monomer diluent - 20% 18% Irgacure 2959 (Ciba) Alpha-hydroxy ketone, photoinitiator 2% 2% 2% HDK T30 (Wacker Chemie AG) Amorphous silica - - 2% Tego Glide 440 (Evonik) Surfactant, leveling agent and lubricant 0.5% 0.5% 0.5% Byk 021 (BYK-Chemie) defoamers 0.2% 0.2% 0.2%

After the application of the handle nubs on plastic shafts, crosslinking is followed by irradiation with UV light and, subsequently, evaluation of the application properties. evaluation criterion Example A Example B Example C Threading when applying + ++ ++++ Bleeding of the pimples before curing ++ + +++++ Liability on ABS ++++ ++++ ++++ curing +++++ +++++ +++++

Evaluation scheme:

• +++++ = very good
• ++++ = good
• +++ = acceptable
• ++ = bad
• + = very bad
• n / A. = not applicable

The preparation according to Example A showed very strong stringing. She was also relatively viscous, which the entire order process designed more difficult. The applied droplets showed too little course, so that the desired diameter of the handle knobs was not reached. Because of the lack of course, the handle knobs were too high. The preparation according to Example B showed a slightly improved threading compared to A, but the applied mass had a clearly too strong course, so that there were nipples with irregular outline shape, greater width and too small height. In contrast, the preparation according to Example C, which contained amorphous silicon dioxide, showed a "very good" graded course of the droplets applied to the surface. Very good here means that the droplets run only so much that the handle nubs have the nominal diameter after UV curing. The threadline, which is always present to some extent in plastic preparations of the present type, was significantly reduced compared to Formulations A and B in such a way that it neither deteriorates the spatial shape and surface smoothness of the handle nubs nor that the surface of the pin shafts would have been contaminated. The adhesion to ABS was good in all three examples, the cure very well.

Example 2:

UV-crosslinkable Kunstatoffzubereitung for black-colored handle knobs with dimensions as in Example 1. The formulation examples D and E are comparative examples, they contain neither amorphous silicon dioxide nor micronized amide wax.

Also, the receiving example H is a comparative example, it does not contain a monomer. raw material function D e F G H I Roskydal UA VP LS 2258 (Bayer Material Science) Aliphatic urethane acrylate, oligomer 75.8% 54.8% 54.8% 54.8% 73.8% 52.8% Roskydal UA XP 2491 (Bayer Material Science) Aliphatic urethane acrylate, oligomer 20% 20% 20% 20% 20% 20% Laromer TPGDA (BASF) Tripropylene glycol triacrylate, reactive monomer diluent - 20% 18% 18% - 20% Irgacure 2959 (Ciba) Alpha-hydroxy ketone, photoinitiator 2% 2% 2% 2% 2% 2% Irgacure 819 (Ciba) Bis-acyl-phosphine, co-photoinitiator 1% 1% 1% 1% 1% 1% HDK T30 (Wacker Chemie AG) Amorphous silicon dioxide, rheological additive Silicon dioxide - - 2% - 2% 1% Helio Beit UV 904 (Bollig & Kemper) Russ preparation, pigment 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% Cray Vallac Super (Cray Vallay) Micronized s Amide wax, Rheological additive - - - 3% - 2% Tego Glide 440 (Evonik) Surfactant, leveling agent and lubricant 0.5% 0.5% 0.5% 0.5% 0.5% 0.5% Byk 021 (BYK-Chemie) defoamers 0.2% 0.2% 0.2% 0.2% 0.2% 0.2%

After the application of structures to plastic shafts, crosslinking is followed by irradiation with UV light and subsequent evaluation of the coating properties. evaluation criterion Example D Example E Example F Example G Example H Example I Threading when applying + ++ ++++ ++++ n / A ++++ Bleeding of the pimples before curing ++ + +++++ +++++ .a. +++++ Liability on ABS ++++ ++++ ++++ ++++ n / A ++++ curing +++++ +++++ +++++ +++++ n / A +++++ (Rating scheme see above!)

In the case of preparation D, a strong string of thread was shown; it was too thick for application. The applied droplets showed a much too low course. There were conditions here as in the above-mentioned preparation A. Formulation E showed a slightly improved threading compared to D, with a clearly too strong course. The result of the experiments was thus comparable to that carried out with preparation B. Formulations F and G, which contained amorphous silica and micronized amide wax, respectively, showed a very "good" grading of the droplets as well as a barely appearing threading Thus conditions were present, as in the above preparation C. The adhesion to ABS was good in all four examples, the curing very well. The preparation H was therefore extremely difficult to handle because its viscosity was too high. Even if it was possible to apply a drop of material to a pin surface, a strong threadline was evident. This preparation was therefore rated na. In the case of Preparation I, micronized amide wax was added in addition to amorphous silica. In this case, results were obtained as in the preparation G. In summary, it can thus be stated that both substances-alone or in a mixture-give good results with regard to the course and the thread tension of the applied preparation, it being precisely the combination of a reactive monomer diluent or monomer and the abovementioned substances that is absolutely necessary.

Claims (12)

1. Method for creating embossed structures on the surface of a pen that serve as gripping pimples, wherein an embossed structureis produced by a drop of a plastic preparation that is applied to the pen surface with the aid of a nozzle, the nozzle being removed from the drop applied to the pen surface and the drop being radiated so as to harden it, wherein the plastic preparation contains a radiation-hardened plastic mass and is composed as follows: plastic mass formed from oligomer and monomer: 40% to 98% photoinitiator system: 0.1% to 30% amorphous silicon dioxide and/or micronized amide wax: 0.3% to 30% colourant: 0% to 60% filler: 0% to 60% further additives: 0% to 10%.
2. Method according to claim 1, characterised in that a plastic preparation is used, which contains at least one acrylate oligomer.
3. Method according to claim 2, characterised by the use of a plastic preparation containing 70% to 80% acrylate oligomer and 1% to 25% acrylate monomer.
4. Method according to claim 2 or 3, characterised by the use of a plastic preparation, wherein the acrylate oligomer is selected from the group of aromatic and aliphatic epoxy acrylates, polyester, polyurethane, oligoether, amino-modified oligoether and polyol acrylates.
5. Method according to claim 4, characterised in that a plastic preparation with 70% to 80% urethane acrylate oligomer and 1% to 15% acrylate monomer is used.
6. Method according to one of the preceding claims, characterised in that the plastic preparation contains 1% to 8% of the photoinitiator system.
7. Method according to claim 6, characterised in that 0.5% to 5% of a photoinitiator and 0.5% to 3% of a co-initiator are contained in the plastic preparation.
8. Method according to one of the preceding claims, characterised by the use of a plastic preparation with 0.5% to 5% of amorphous silicon dioxide and/or micronized amide wax.
9. Method according to claim 8, characterised in that a plastic mass is applied to the pen surface, which is composed as follows: urethane acrylate oligomer: 70% to 80% acrylate monomer: 1% to 15% amorphous silicon dioxide and/or micronized amide wax: 0.5% to 5% photoinitiator: 0.5% to 5% co-initiator: 0.5% to 3% other additives: 0.1% to 10%.
10. Method according to claim 9, characterised by the use of a preparation, which contains 0.3% to 2% of a levelling and lubricating agent and/or 0.1% to 1% of a defoamer.
11. Method according to one of the preceding claims, characterised by the use of a plastic preparation containing a filler from the group of kaolin, talc, barium sulphate, titanium white, calcium carbonate and mica.
12. Method according to one of the preceding claims, characterised by the use of a plastic preparation containing a filler from the group of aluminium silicate hollow spheres, expanded hollow spheres, PU-soft feeling beads, micronized plastics such as polypropylene or PTFE and PE wax.

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