EP1700713B1 - Process for manufacturing of coatings with structured surface, applied especially for pencils, and object with structured surface - Google Patents

Abstract

The method involves application of the coating (4) on the part of the surface (3), which contains expandable particles. In the surface range of the coating, the particle to be expanded are brought, through which a raised structure develops in this surface range. The method also involves use of thermally expandable particles.

Description

The invention relates to a method for the production of surface coatings of pens and a pin with a surface coating. Surfaces of everyday objects are often provided with a coating, for example by spraying or dipping with a paint coating. For a visually pleasing surface of an object, further measures for surface design are usually required. It is also common for a coating to have special haptic properties, for example increased grip. The application of a coherent, the grip-increasing coating prepares usually no special difficulties. This is different if the grip of the surface is to be achieved by protruding surface regions of the coating, for example raised structures of non-slip masses in the form of knobs, ribs or the like. At one off DE 203 14 274 U1 known pen are a variety of nubs in the form of an initially flowable, later solidifying mass applied to the pin surface. In EP 0376322 For example, a method is described in which three-dimensional images are produced by forming on an expandable particle-containing base layer an image having a color which absorbs light under heating. Below the color particles go through the heating in an expanded state. Out GB 1 442 823 It is known on a surface of an initially flowable and later to raised structures apply hardening mass. In the known method, the applied mass contains particles which when heated in an expanded state and thereby increase the volume of the applied structures. Due to the flowability at the time of application, a precisely reproducible form is difficult to achieve, which leads to intolerable results, in particular, when a pattern consisting of a plurality of uniform structures is to be produced. The flowing of the applied masses creates structures or patterns with blurred or merging edges. The exact controlled application of flowable masses is also technically relatively expensive, since devices with exactly working metering systems are required.

On this basis, it is the object of the invention to propose a method with which can produce in a technically simple manner on pens high-quality, optically and haptically pleasing coatings with raised areas. The task is still to create a pen with a high-quality, optically and haptically pleasing surface coating.

These objects are achieved according to claim 1 and claim 11, respectively. In the method according to claim 1, at least on a part of the surface, a coating composition is applied in which expandable particles are contained, and in a partial area of the coating, the particles are brought to expand, whereby the partial surface area protrudes from the coating as a raised structure. This procedure results in a variety of design options, by surface areas of different thickness and thus, for example, raised structures to increase the grip can be produced in a technically simple manner on a surface of an article, in particular a lead, color, and cosmetic pencil. This is done by a selective expansion of the particles preferably contained in the applied coating thermally expandable. For example, the proportion of the raised surface areas may be greater than the remaining areas of the coating, so that the design elements such as patterns or lettering are recessed.

In an especially preferred procedure, hollow hollow spheres, in particular those which have an average particle size of 2 μm to 45 μm in the unexpanded state, are used as expandable particles. Hollow microspheres consist of a thermally softenable polymer sheath that encloses an easily evaporable liquid. Upon heating, the polymer material softens and the hollow microsphere is inflated by the liquid evaporating inside many times its original size. The expanding hollow microspheres thus lead to an increase in the volume of the coating, resulting in raised structures or surface areas having an increased surface roughness and grip.

In addition, however, the use of inorganic particles such as expanded mica or in particular expandable graphite or particles of expandable plastics is conceivable.

The expansion of the particles is preferably carried out in contact technology. This is a heated at least to the required expansion temperature body with one of the outline shape and surface of the raised surface area of the coating corresponding contact surface brought into contact with the coating. In contrast to the conventional methods mentioned in the introduction, patterns can be produced with sharply delimited and, above all, exactly uniform, raised structures. In order to heat an area corresponding to the later raised surface area, in a preferred variant of the method, heated bodies integrated in a lifting ram, for example, are moved away from the surface of the object towards and after expansion of the particles.

The expansion of the particles can also take place without contact, for example by applying a region of the coating corresponding to a raised surface area to a high-energy light beam, for example a laser beam. The cross-sectional area of such a light beam can also be set exactly, in particular if laser light is used.

The application of the coating is in any case easily possible for example by dipping, spraying, brushing, with the puncture process or by screen printing. The latter method is suitable, for example, if only partial areas of the surface are to be provided with a coating containing expanding particles. In a puncture method, for example, wood-sheathed pins are inserted via an input opening into a container containing liquid coating material, the pins leaving the container again via an exit opening, on which superfluous coating material is stripped off. After drying or already in the uncured state of the coating, the particles of a certain partial surface area in the appropriate manner, in particular converted by heat in its expanded state.

The expanding particles may partially breach the surface of the coating, resulting in cracks and burrs that give an optical and a haptic effect on the one hand. It is conceivable that a material is used for a non-slip coating or non-slip grip. The expanded particles are then used primarily to form raised partial surface areas or structures and, for example, as a result of the mentioned formation of cracks and burrs, to further increase the grip. It is also conceivable, however, that the particles are preferably expanded contactlessly when the coating composition is not fully hardened, for example, is still viscous. As a result, raised areas could be obtained in which the expanded particles do not break the surface of the coating but are coated with coating material.

In cases of pens or other objects of circular or oval cross-section, such as tool handles such as brush or hammer handles, the above-mentioned contact technique may be modified so that the object to be treated is unrolled on a surface of a body at least the expansion temperature of the particles having contact surfaces are arranged. With this rolling technique, it is possible to produce raised structures in complex patterns in a technically very simple way.

One of the above-mentioned object solving pin has a coating with expandable particles, wherein in a partial surface area of the coating, the particles expands are, whereby this protrudes as a raised structure of the coating. As already described above, in addition to the advantageous simple production in particular the degree of design freedom for surface designs should be emphasized. For example, the respective proportion of the raised or non-raised partial surface areas may vary. Raised coating areas can form about the much larger part of a coated surface, ie the flavor-influencing elements of the coated surface, as already mentioned above, formed by depressions, for example in the form of a lettering. Another design option is that the coating composition and the admixed particles have different colorations. As a result, raised and not raised or recessed partial surface areas can be produced with a distinctly different color appearance.

The design effects can be used particularly advantageously for mass products such as lead, color and cosmetic pencils. This applies in particular to wood-clad pins. Preference is given to hollow microspheres as expandable particles, these having an average particle size of 5-20 μm in the initial state and being at least doubled in the expanded state.

Fig. 1

eine schematische Querschnittsdarstellung durch einen Oberflächenbereich eines Gegenstands, beispielsweise eines Stifts, welche die thermische Behandlung einer expandierbaren, Partikel enthaltenden Beschichtung in Kontakttechnik verdeutlicht,

Fig. 2

den Oberflächenbereich von Fig. 1 nach der thermischen Behandlung,

Fig. 3

eine Draufsicht auf einen Stift, dessen Oberfläche nur teilweise mit einer expandierbare Partikel enthaltenden Beschichtung versehen ist,

Fig. 4

eine schematische Querschnittsdarstellung, welche eine Verfahrensvariante der Kontakttechnik nach Fig. 1 zeigt,

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

Fig. 1

3 shows a schematic cross-sectional view through a surface region of an object, for example a pin, which illustrates the thermal treatment of an expandable, particle-containing coating in contact technology,

Fig. 2

the surface area of Fig. 1 after the thermal treatment,

Fig. 3

a top view of a pin whose surface is only partially provided with a coating containing expandable particles,

Fig. 4

1 is a schematic cross-sectional view showing a variant of the method according to FIG. 1,

An article, hereinafter referred to a wood-clad pencil 1, whose surface with raised structures or surface areas 2.2a to be provided, is initially applied either on its entire surface 3 or a partial surface 3a (Fig. 3), an expandable particles, such as hollow microspheres coating 4 containing. In this case, for example, hollow microspheres with a coat of mixed polymer (CAS No. 25214) can be used, which are available from Akzo Nobel Chemicals GmbH, D-46446 Emmerich. As a starting material for the coating can be used as a preparation according to the examples below. In the case of a pin 1, which is to be provided with a total of 4 coating, the above-mentioned puncture method is advantageously used. If, on the other hand, only partial surfaces 3a are to be provided with a coating 4 containing expandable particles, as in the case of the pen 1a shown in FIG. 3, this can be done, for example, by screen printing. After the coating 4 has hardened, a selective expansion is performed. For this purpose, an area 5 of the surface 3 or the coating 4 is heated to a temperature which is above the expansion temperature of the particles used in each case. The size of the area 5 corresponds to a later raised area 2.2 a. If, as shown in FIG. 1, the contact technique is used for the expansion of the particles, a body 6 heated to at least the respective expansion temperature is brought into contact with the coating 4 with a contact surface 7 corresponding to a raised surface area 2. When a plurality of raised structures 2,2a are to be produced, a corresponding number of bodies 6 are required. These can all be arranged on a common carrier 8, for example in one or more rows. The contact surface 7 is substantially adapted to the contour of the surface to be treated, for example in a pen as well as its surface curved in a cylindrical shape. The cross-sectional shape of a raised surface area 2,2a can be influenced to some extent by the shape of the contact surface 7. As illustrated in FIG. 2, the upper side of a surface region 2 can be formed approximately corresponding to the surface of the pin 1, ie it runs approximately coaxially to the pin surface 3. However, it is also conceivable, for example, a spherical shape of a raised surface region 2 a. Such a configuration is supported, for example, by a complementary, ie concavely shaped, contact surface 7a.

In the case of the pin 1a of FIG. 3, 3 partial surfaces 3a are applied on the surface thereof by means of a screen-printing method or else in another way. Within the partial surfaces 3 a, there are raised structures or surface regions 2 b which have been produced, for example, by the contact technique described above.

FIG. 4 schematically shows a variant of a method in which a cylindrical object, such as a pin 1b, is rolled on the surface of, for example, a plate-shaped tool 10 in the direction of the arrow 11 in order to trigger particle expansion in certain surface areas. For this purpose, in the tool heated bodies corresponding heating elements 12 are present, which have a flush with the surface of the tool contact surface 7a. The heating elements 12 are arranged in a grid corresponding to the later pattern of the raised structures produced. Its contact surface 7a corresponds to the size of the raised surface areas 2c to be generated. The respectively required relative speed between the pin 1b and the tool 10 depends on the desired contact duration between the coating 4 and a heating element 12. The thermal treatment in the coating 4 can also be carried out so that the pin is held stationary and rotatable about its central longitudinal axis, wherein the tool 10 is moved, for example in the direction of the arrow 11.

By way of example, the following formulations may be considered as a coating (percentages are by weight):

Example 1: For the puncture process suitable water-based paint

Binder: aqueous polyurethane dispersion (Alberdingk APU 1061) 1) 83% Polyurethane thickener (Rheolate 255) 2) 1 % Polyurethane thickener (Rheolate 244) 2) 2.3% Dispersing additive (Disperbyk-192) 3) 1 % Expandable hollow microspheres (Expancel 551 DU40) 4) 9% Wetting agent (Tego Wet 510) 5) 0.3% Mineral oil-based defoamer (Drewplus T 4202) 6) 0.4% aqueous pigment preparation (Levanyl Blue G-LF) (Expancel 820 SL 40) 7) 3%

Example 2: Colorless water-based topcoat

Binder: aqueous polyurethane dispersion (Alberdingk U 210) 1) 80% expandable hollow microspheres (Expancel 820 SL 40) 4) 18% Polyurethane thickener (Rheolate 244) 2) 1.5% Thickener (DSX 3290) 8th) 0.2% Mineral oil-based defoamer (Drewplus T 4202) 6) 0.3%

Example 3: Colored UV-curable lacquer

UV binder: (Genome 1343) 9) 13% Polymerization inhibitor (Genorad 16) 9) 0.3% UV binder (Genome 5275) 9) 11% Thickener (Aerosil 380) 10) 0.3% UV binder, (Specialty Resin 01-554) 9) 16% UV photoinitiator (Irgacure 819) 11) 1 % UV photoinitiator, (Darocur 1173) 11) 2% UV pigment preparation, (Microlith Black C-K) 11) 0.5% Defoamer (Byk 020) 3) 0.2% Softfeeling additive (Daiplacoat RHC-731 Clear) 12) 11% Matting agent (Syloid Rad 2105) 13) 3% UV binder, (Genomer 6050 / TM) 9) 29% Expandable hollow microspheres (Expancel 551 DU 40) 4) 12.7%

Example 4: Colorless solvent-based topcoat

Binding agent (nitrocellulose H 22) 14) 19% Plasticizer based on tributyl citrate (Citrofol A 1) 4) 5% Resin binder, (Kunstkarz SK) 15) 6% Solvent (acetone) 16) 60% expandable hollow spheres (Expancel 091 DU 120) 4) 10%

Example 5: For water-based printing inks suitable for screen printing

Binder: aqueous polyurethane dispersion (Liopur 97-282) 17) 50.6% Polyurethane thickener (Rheolate 244) 2) 3% aqueous pigment preparation (Levanyl Blue G-LF) 7) 0.7% aqueous pigment preparation (Levanox white RNZ-SF) 7) 5% Solvent (1,2-propanediol) 18) 10% Defoamer (EFKA 2526) 19) 0.7% Expandable hollow microspheres (Expancel 091 DU 140) 4) 30%

Manufacturer:

1. 1) Alberdingk Boley GmbH, D-47829 Krefeld
2. 2) Elementis, Ambachtsweg 8, 4906 CH Oosterhout, The Netherlands
3. 3) Byk Chemie GmbH, D-46462 Wesel
4. 4) Akzo Nobel Chemicals GmbH, D-46446 Emmerich
5. 5) Tego Chemie Service GmbH, D-45127 Essen
6. 6) Drew Ameroid Germany GmbH, D-63073 Offenbach
7. 7) Bayer AG, D-51368 Leverkusen
8. 8) Cognis Germany GmbH, D-40551 Dusseldorf
9. 9) Rahn AG, CH-8050 Zurich
10. 10) Degussa AG, D-60287 Frankfurt a. M.
11. 11) Ciba, CH-4002 Basel
12. 12) Gustav Grolman GmbH & Co. KG, D-41468 Neuss
13. 13) Grace Davison Europe, D-67547 Worms
14. 14) Hagedorn AG, D-49078 Osnabrück
15. 15) Degussa Hüls / Creanova Specialty Chemicals GmbH, D 53859 Niederkassel
16. 16) Biesterfeld Spezialchemie GmbH, D-20095 Hamburg
17. 17) Synthopol Chemistry, D-21605 Buxtehude
18. 18) Merck KGaA, D-64293 Darmstadt
19. 19) EFKA Additives B.V., 8440 AN Heerenveen, Netherlands

LIST OF REFERENCE NUMBERS

1

pen

2

raised surface area

3

surface

3a

subarea

4

coating

5

Areal

6

body

7

contact area

8th

carrier

9

top

10

Tool

11

arrow

12

heating element

Claims (14)

1. Method for the surface coating of pins, in which

   - a coating (4) in which thermally expandable particles are contained is applied onto at least one part of the surface (3), and

   - in a part surface area (2, 2a, 2b, 2c) of the coating (4), the particles are brought to expansion, as a result of which the part surface area (2, 2a, 2b, 2c) projects as a raised structure from the coating.
2. Method according to Claim 1, characterised by the use of thermally expandable particles.
3. Method according to Claim 2, characterised in that thermally expandable micro hollow spheres are used.
4. Method according to Claim 3, characterised by the use of micro hollow spheres with a mean size from 2 µm to 45 µm in the non-expanded state.
5. Method according to any one of Claims 2 to 4, characterised in that the heating of an area (5) corresponding to a later raised part surface area (2, 2a) is effected by contact with the contact surface (7) of a body (6) heated at least to the expansion temperature of the particles.
6. Method according to Claim 5, characterised in that for the heating of the area (5), the body (6) is brought towards the surface (3) and moved away from it after the expansion of the particles.
7. Method according to Claim 6, characterised in that it is used for pins which are triangular or hexagonal in cross-section.
8. Method according to Claim 5, characterised in that a pin with round or oval cross-section is rolled on the surface of a tool (10), arranged on which are contact surfaces (7a) having at least the expansion temperature of the particles.
9. Method according to one or more of the preceding claims, characterised in that raised part surface areas (2, 2a) are thereby produced on the surface (3) of a pin (1) made of wood.
10. Pin, the surface of which is provided at least in part with a coating (4), characterised in that the coating (4) contains expandable particles and in that the particles are expanded in a raised part surface area (2, 2a) of the coating, as a result of which the part surface area (2, 2a, 2b, 2c) projects as a raised structure from the coating.
11. Pin according to Claim 10, characterised in that the pin (1) is a pin encased in wood.
12. Pin according to Claim 10 or 11, characterised in that the coating (4) contains micro hollow spheres as expandable or expanded particles.
13. Pin according to Claim 12, characterised in that the micro hollow spheres have in the initial state a mean particle size of 2 to 45 µm and in the expanded state are enlarged to at least double the size.
14. Pin according to any one of Claims 10 to 13, characterised in that the portion of the part surface areas (2, 2a, 2b, 2c) with expanded particles is larger than the portion of the surface areas with non-expanded particles.

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