EP1732767A1

EP1732767A1 - Sealing of plastic inscriptions

Info

Publication number: EP1732767A1
Application number: EP05715991A
Authority: EP
Inventors: Sylke Klein; Tanja Sandner
Original assignee: Merck Patent GmbH
Current assignee: Merck Patent GmbH
Priority date: 2004-03-30
Filing date: 2005-03-11
Publication date: 2006-12-20
Also published as: TW200609123A; US8343412B2; BRPI0509290B1; KR20060129515A; US20110117335A1; RU2405678C2; TWI367168B; RU2006138147A; WO2005097514A1; JP5296374B2; JP2007530321A; US20070154642A1; BRPI0509290B8; BRPI0509290A

Abstract

The invention relates to the sealing of plastic inscriptions that have been, preferably indirectly, produced by means of a laser on the plastic surface.

Description

Sealing of plastic lettering

The present invention relates to the sealing of plastic inscriptions, which have been generated by means of lasers on the plastic surface, preferably indirectly. 5 With the help of laser beams of different wavelengths, it is possible to permanently mark and label materials and production goods.

^" 10 In the following, the term" labeling "should be understood to mean any type of marking by the laser, ie labeling, marking, coding, etc.

“Colored laser marking” means the marking of plastics 15 using all colored and achromatic pigments or dyes (all colors including black, white and all shades of gray).

The markings and / or inscriptions are made by the action of laser energy 0 1. on the material itself (direct inscription) or 2. on an inscription medium that is transferred from the outside to the material to be inscribed (indirect inscription). 5 For example, with inscription method 1) metals react to laser irradiation with different tempering colors, woods become dark at the irradiated areas (charring) and plastics, e.g. PVC, depending on the color of the plastic, show light or dark discolorations (foaming, carbonization).

30 These effects are often reinforced or initiated in plastics by the addition of laser-sensitive pigments. The disadvantages are usually that only the "colors" white and black or different gray and bleaching levels can be achieved, and that the whole

35 Plastic material in the master batch, the laser-sensitive pigments must be added.

If labeling method 2) hits a laser beam of suitable energy and wavelength (e.g. IR laser) with a labeling medium and if it is in contact with the material to be labeled, this will be

Transfer the labeling medium to the material and fix it there. Materials can be labeled indirectly with suitable colored and achromatic pigment or dye mixtures, suspensions, pastes or laser foils or tapes. In this way, colored and black / white lettering with high contrast is possible. The amount of laser-sensitive pigments actually required for labeling is considerably less than e.g. with masterbatch addition (labeling method 1) or is not required in certain applications.

Labeling media made of glass frits or glass frit precursors with laser energy absorbers, which - depending on the desired color - are mixed with inorganic and organic pigments, metal oxides, organometallic substances or metal powders, are generally known to the person skilled in the art. Such methods are e.g. described in WO 99/16625, U.S. 6,238,847, U.S. 6,313,436 and WO 99/25562.

After applying the pigment and / or dye mixtures directly to the medium to be labeled, e.g. by spraying, brushing, sprinkling, electrostatic charging, etc., or on carrier substrates such as tapes, foils or the like, the required laser energy (1-30 W output power irradiated and labeled in cw mode) or laser energy density (in pulsed mode 100 W / cm ² - 3 GW / cm ² ). In this way, glass, ceramics, metal, stone, plastics and composites can be labeled. Such labeling methods are known for example from WO 03/035411, WO 03/080334 and WO 03/080335.

The published patent applications EP 1279517 A1 and DE 19942316 A1 specifically for the colored laser marking and lettering of Plastics laser-sensitive mixtures of glass pigments and plastic granules are described.

A major disadvantage of the indirect laser inscription of plastics produced in these processes is the locally very high pigment or dye concentration at the inscription locations, which often leads to smeared, blurred inscriptions, which can also bloom or bleed out later. This occurs especially when using organic pigments or dyes.

While with conventional plastic coloring with maximum

Pigment concentrations of> 0.5% for organic pigments and> 2% for inorganic pigments, the pigment concentrations are due to e.g. according to WO 99/16625 laser-inscribed plastic areas well over 20%.

This overpigmentation leads - depending on the inscribed plastic and the later usage temperature - to the migration of the pigments or dyes to the plastic surface, to the so-called blooming.

If the inscriptions are brought into contact with other materials and there is a transfer of the excess pigments or dyes into these materials, one speaks of bleeding out.

This overpigmentation makes additional post-cleaning and drying steps necessary, which is technologically undesirable or unacceptable, in particular for an inline production process with product labeling as the last process step.

In addition, the lettering bleeds or fades when in use or fades, for example due to environmental influences, etc.

For certain applications, such as labeling of foodstuffs, packaging for pharmaceuticals, children's toys, Medical devices, etc., labels that bleed out or bloom out in this way cannot be used at all.

The object of the present invention is therefore to achieve non-blooming, non-bleeding laser marking of plastics with high edge sharpness and high resistance to environmental influences, the laser marking being generated on the plastic surface, preferably indirectly.

Surprisingly, it was found that the blooming or bleeding out of the plastics, which were colored with a laser, was prevented by sealing the marked areas during the marking process. The sealing is carried out with the aid of transparent layers of polymers, which preferably have glass temperatures> 90 ° C., in particular between 100-120 ° C. This polymer layer can be applied as a separate layer or enclose the colorants and seal them.

The invention relates to a method for the permanent and abrasion-resistant colored labeling of plastics, characterized in that the bleeding or blooming of the colorants and / or absorbers (laser-sensitive pigments) at the labeled points in the plastic is prevented by using a Laser's inscribed areas are sealed with a transparent polymer during the inscription process itself or immediately afterwards.

In comparison to the prior art, the method according to the invention is distinguished by the following features:

Smearing and / or later bleeding / blooming of the pigments or dyes is prevented. Unwanted cleaning steps after the actual labeling process are saved. The color fastness of the labeling is guaranteed in later use. The polymer layer for the seal can be applied in a 1-step process together with the laser inscription or in a 2-step process on the inscription made in the 1st step. Layer systems according to Figs. 1-12 have proven to be particularly suitable.

The plastic is preferably inscribed with a laser by indirect inscription, for example as described in WO 99/16625 or in the unpublished DE 10352857. The plastics are labeled in color by introducing the labeling medium into the plastic substrate using laser energy. The labeling medium detaches from the carrier film and then bonds permanently to the likewise heated and thus locally softened plastic surface.

1-step process in Figs. 1-6 is the 1-step process in the invention

The procedure is shown schematically. In Fig. 1, the layer system consists of a laser light-permeable and durable carrier layer (1), a laser-sensitive energy absorber layer (2), a separating layer (3), a separate sealing layer (4) and finally a labeling medium (5), the latter containing pigments and /or

Dyes. This layer system is brought into close contact with the plastic to be labeled with the labeling medium side.

Alternatively, the colorant itself can be coated with a sealing polymer layer or embedded in a polymer matrix (6) (Fig. 2, 4, 6).

It is also possible to incorporate the energy absorber into the carrier layer (layer 7 in Figs. 3, 4).

With a suitable laser, the labeling of a plastic with the seal is created in this 1-step process. The energy required for this is transferred via the energy absorber layer (2, 7) to the separating layer (3), which softens and thus the sealing layer (4) and the labeling medium (5) or that sealed colorant (6) transfers to the plastic. The laser energy must be selected so that the plastic at the labeling points also softens and a firm connection with the sealing layer (4) or with the sealed color center! (6) forms.

In certain applications such as self-absorbing

Plastics (e.g. dark colored plastics, good affinity of the plastic for the sealing polymer) can already be labeled without additional absorbers (Fig. 5, 6)

2-step process

In the 2-step process, the labeling process is separated from the subsequent seal. In the first step, the label is created. This can be done with layered structures as shown in Fig. 7 to 10.

The energy absorber is applied as a separate layer (2) (Fig. 7) to a laser-light-permeable and durable carrier film (1), applied or incorporated into the carrier film (7) (Fig. 8) or is not required for self-absorbing plastics (Fig. 9), the labeling medium (5) as a separate layer (Fig. 7-9) or as a layer (8) consisting of a mixture of labeling medium (5) and energy absorber (2) (Fig. 10).

Using a suitable laser, the necessary energy is transferred via the energy absorber layer (2, 7) to the labeling medium (5) and to the plastic, or is immediately transferred to the plastic via the layer (8). The labeling medium (5) merges with the softened plastic and leads to the plastic being labeled.

In the second step, the seal is made with a layer structure (Fig. 11, 12) consisting of a laser-light-permeable and durable carrier layer (1), a laser-sensitive energy absorber layer (2 or incorporated in 7), a separating layer (3) and a sealing layer ( 4) generated. With a suitable laser, the necessary energy is transferred via the energy absorber layer (2, 7) to the separating layer (3), which softens and thus transfers the sealing layer (4) to the plastic. The laser energy must be selected so that the plastic softens again at the labeling points and forms a firm connection with the sealing layer.

All materials which are ideally transparent and / or translucent in the specified wavelength range for the laser light and which are not damaged or destroyed by the interaction with the laser light are suitable as materials for the carrier layer (1).

Materials such as Glass and plastics, which are ideally used in the form of foils, tapes or plates and preferably have layer thicknesses of 5-250 μm, in particular 10-150 μm and very particularly preferably 15-75 μm.

Suitable plastics are preferably thermoplastics. In particular, the plastics consist of polyesters, polycarbonates, polyimides, polyacetals, polyethylene, polypropylene, polyamides, polyester esters, polyether esters, polyphenylene ethers, polybutylene terephthalate, polyethylene terephthalate, polymethyl methacrylate, polyvinyl acetal, polyvinyl chloride, polystyrene, acrylonitrile butadiene styrene (ABS) Styrene acrylic esters (ASA), polyether sulfones and polyether ketones and their copolymers and / or mixture.

Of the plastics mentioned, polyester, polyethylene terephthalate, polyethylene, polypropylene, polycarbonates and polyimides are particularly preferred.

Especially for labeling and marking three-dimensional

Plastic parts or surfaces are suitable for unstretched amorphous plastic carrier films made of polyethylene terephthalate, polyester and polyamide. All materials can be used as energy absorbers that sufficiently absorb the laser light energy in the specified wavelength range and convert it into thermal energy.

The energy absorbers suitable for the marking are preferably based on carbon, soot, anthracene, IR-absorbing colorants such as perylene / rylene, pentaerythritol, phosphates such as copper hydroxide phosphates, sulfides such as molybdenum disulfide, oxides such as antimony (III) oxide , Fe ₂ 0 ₃ and Ti0 _2l bismuth _oxychloride , platelet-shaped, in particular transparent or _semi -transparent substrates made of, for example, layered silicates, such as synthetic or natural mica, talc, kaolin, glass platelets, Si0 ₂ platelets or synthetic carrier-free platelets. Platelet-shaped metal oxides, such as platelet-shaped iron oxide, aluminum oxide, titanium dioxide, silicon dioxide, LCP's (Liquid Crystal Polymers), holographic pigments, conductive pigments or coated graphite platelets are also suitable.

Metal powders which can be uncoated or also covered with one or more metal oxide layers can also be used as platelet-shaped pigments; preferred are e.g. Al, Cu, Cr, Fe, Au, Ag and steel plates. If corrosion-prone metal plates such as Al, Fe or steel plates are used uncoated, they are preferably covered with a protective polymer layer.

In addition to platelet-shaped substrates, spherical pigments can also be used, e.g. made of AI, Cu, Cr, Fe, Au, Ag and / or Fe.

Particularly preferred substrates are mica flakes coated with one or more metal oxides. Colorless, highly refractive metal oxides, such as, in particular, titanium dioxide, antimony (III) oxide, zinc oxide, tin oxide and / or zirconium dioxide, and colored metal oxides, such as, for example, chromium oxide, nickel oxide, copper oxide, cobalt oxide and in particular iron oxide (Fe ₂ 0 ₃ , Fe ₃ 0). Antimony (III) oxide is particularly preferably used alone or in combination with tin oxide as the energy absorber. These substrates are known and are mostly commercially available, eg under the trademark Iriodin ^® Lazerflair from. Merck KGaA, and / or can be prepared by standard methods known to the skilled person.

Pigments based on transparent or semi-transparent platelet-shaped substrates are e.g. described in German patents and patent applications 14 67 468, 19 59 998, 20 09 566, 22 14 454, 22 15 191, 2244298, 23 13 331, 25 22 572, 31 37 808, 31 37 809, 31 51 343, 31 51 354, 31 51 355, 32 11 602, 32 35 017, 38 42 330, 44 41 223.

Coated Si0 ₂ platelets are known, for example, from WO 93/08237 (wet chemical coating) and DE-OS 196 14 637 (CVD process).

Multilayer pigments based on phyllosilicates are known, for example, from German published documents DE 196 18 569, DE 196 38 708, DE 197 07 806 and DE 198 03 550. Multi-layer pigments which have the following structure are particularly suitable:

Mica + Ti0 ₂ + Si0 ₂ + Ti0 ₂

Mica + Ti0 ₂ + Si0 ₂ + Ti0 ₂ / Fe ₂ 0 ₃ Mica + Ti0 ₂ + Si0 ₂ + (Sn, Sb) 0 ₂ Si0 ₂ platelets + Ti0 ₂ + Si0 ₂ + Ti0 ₂

Particularly preferred are laser light absorbing substances

Anthracene, perylene / rylene, for example ter- or quarter-rylenetetracarboxydimides, pentaerythritol, copper hydroxide phosphates, molybdenum disulfide, antimony (III) oxide, bismuth oxychloride, carbon, carbon black, antimony, Sn (Sb) 0 ₂ , Ti0 ₂ , silicates, Si0 ₂ platelets, mica coated with metal oxides and / or Si0 ₂ platelets, conductive pigments, sulfides, phosphates, BiOCI, or mixtures thereof.

The energy absorber can also be a mixture of two or more components. According to the invention, it is applied as a layer (2) on the Carrier (1) pulled on (Fig. 1, 2, 5, 8) or incorporated into the carrier layer (Fig. 3, 4, 6, 9), in proportions of 2 - 50% by weight.

If these energy absorbers are already used as additives or for coloring the plastic, under appropriate conditions, labeling without energy absorber can be done in the labeling tape according to Fig.

5, 6 and 9, respectively.

The labeling medium (5) can be applied as a paste or as a layer with a support. The labeling medium essentially consists of colorant, binder and optionally polymer component, preferably in dissolved form or in the form of particles and additives.

Both organic and inorganic colorants can be used for labeling. All colorants known to the person skilled in the art which do not decompose during laser irradiation are suitable. In which

Colorants can also be a mixture of two or more substances. The proportion of colorants in the labeling medium is preferably 0.1-30% by weight, in particular 0.2-20% by weight and very particularly preferably 0.5-10% by weight, based on the total mass of the labeling medium (colorant + binder + solvent + if necessary polymer component).

All organic and inorganic dyes and pigments known to the person skilled in the art are suitable as colorants. Azo pigments and dyes, such as e.g. Mono-, diazo pigments and dyes, polycyclic pigments and dyes such as e.g. Perinones, perylenes, anthraquinones, flavanthrones, isoindolinones, pyranthrones, anthrapyrimidines, quinacridones, thioindigo, dioxazines, indanthronones, diketo-pyrolo-pyrroles, quinone phthalones, metal-complexing pigments and dyes such as e.g. Phthalocyanines, azo, azomethine, dioxime,

Isoindolinone complexes, metal pigments, oxide and oxide hydroxide pigments, oxide mixed phase pigments, metal salt pigments, such as chromate, chromate-molybdate mixed phase pigments, carbonate pigments, sulfide and sulfide selenium pigments, complex salt pigments and silicate pigments. Of the colorants mentioned, copper phthalocyanines, dioxazines, anthraquinones, monoazo and diazo pigments, diketopyrolopyrrole, polycyclic pigments, anthrapyrimidines, quinacridones, quinaphtalones, perinones, perylenes, acridines, azo dyes, phthalocyanines, xanthenes and phenoxides, oxidic oxides, colored oxides, are particularly preferred -Mixed phase pigments, sulfide and

Sulphide-selenium pigments, carbonate pigments, chromate, chromate-molybdate mixed phase pigments, complex salt pigments and silicate pigments.

The colorant / absorber ratio for the 2-step process (FIG. 10) is preferably 10: 1- 1:10, in particular 5: 1 - 1: 5, very particularly preferably 4: 1 - 1: 4.

A polymer component can be added to the labeling medium to improve adhesion. It preferably consists of low melting point polymers such as e.g. Polyesters, polycarbonates, polyolefins, polystyrene, polyvinyl chloride, polyimides, polyamides, polyacetals and copolymers made from the polymers mentioned, and terpolymers made from vinyl chloride, dicarboxylic acid esters and vinyl acetate or hydroxyl, methacrylate or mixtures thereof. The polymer component can be dissolved or undissolved in the labeling medium as a fine powder. The particle sizes are preferably 10 nm-100 μm, in particular 100 nm-50 μm and very particularly preferably 500 nm-5 μm. A mixture of different polymer particles can also be used, whereby both the particle sizes and the chemical composition can differ.

The labeling medium preferably contains 10-50% by weight. in particular 15-40% by weight, and very particularly preferably 20-35% by weight, of polymers based on the total mass of the color paste with colorant + binder + solvent + polymer component.

The ratio of polymer component / colorant is preferably 200: 1-1: 1, in particular 100: 1-2: 1, very particularly preferably 70: 1-3: 1.

The labeling medium contains a binder as a further component. The binder enables the inscription layer to be applied homogeneously to materials such as glass and plastics, which are ideally in the form of foils, tapes or plates.

All binders known to the person skilled in the art are suitable, in particular cellulose, cellulose derivatives, such as e.g. Cellulose nitrate, cellulose acetate, hydrolyzed / acetalized polyvinyl alcohols, polyvinyl pyrrolidones, polyolefins, e.g. Polypropylenes and their derivatives, polyacrylates as well as copolymers of ethylene / ethylene acrylate, polyvinyl butyrals, epoxy resins, polyesters, polyisobutylene, polyamides.

Any additives that are added enable the labeling medium (5) to come into close contact with the plastic when writing and create a firm connection between the labeling medium (5) and the seal (4). The additives preferably consist of polymers and copolymers of polyvinyl acetates, methyl, ethyl, butyl methacrylates, unsaturated polyester resins or mixtures thereof.

The separating layer (3) is preferably formed from ester wax or polyvinyl alcohol. The release layer must release the sealing layer from the tape easily and completely (without damage) when heated.

The sealing layer (4) can consist of polymers, preferably with glass transition temperatures> 90 ° C, in particular of polymers of styrene, methyl methacrylate or hydroxy-functional acrylates, PE waxes and dispersions, polyvinyl fluoride and nitrocellulose as binders.

The layer thicknesses of the multilayer systems are preferably: carrier layer (1, 7) 5-250 μm, preferably 15-75 μm energy absorber layer (2) 0.5-150 μm, preferably 1.0-120 μm separating layer (3) 0.1-1 μm, preferably 0.2-0.9 μm sealing layer (4) 1-10 μm, preferably 4-9 μm labeling layer (5, 6) 1- 150 μm, preferably 15-100 μm Layer (8) of labeling medium and energy absorber: 10-150 μm, preferably 15-100 μm

The layer thicknesses of the multilayer systems should not exceed a total thickness of 10-350 μm, preferably 10-250 μm and in particular 12-100 μm, since if the layer systems are too thick, they have a sharp edge

Marking and complete sealing of the marking is not guaranteed.

The multi-layer systems described are placed on the plastic and with the necessary contact pressure, e.g. mechanically, by means of vacuum or by means of optionally added heat-activatable additives in close contact with the areas to be labeled. The lettering is done with a suitable laser in the beam deflection process or mask process.

Depending on the type of plastic, all lasers known to the person skilled in the art can be used for the inscription. The laser parameters depend on the respective application and are easy to determine by a specialist.

The laser inscription is such that the sample body is brought into the beam path of a laser, preferably an Nd: YAG or Nd: YV0 laser. Labeling with an excimer laser, e.g. possible using a mask technique. However, the desired results can also be achieved with other conventional laser types which have a wavelength in a high absorption range of the laser light-absorbing substance used. The marking obtained is determined by the irradiation time (or the number of pulses in the case of pulse lasers) and the irradiation power of the laser and of the plastic system used. The power of the lasers used depends on the respective application and can be easily determined by a specialist in individual cases.

The laser used generally has a wavelength in the range from 157 nm to 10.6 μm, preferably in the range from 532 nm to 10.6 μm. For example, here are CO ₂ lasers (10.6 μm) and Nd: YAG lasers (1064 or 532 nm) or pulsed UV laser mentioned. The excimer lasers have the following wavelengths: F ₂ excimer laser (157 nm), ArF excimer laser (193 nm), KrCI excimer laser (222 nm), KrF excimer laser (248 nm), XeCI excimer laser (308 nm ), XeF excimer laser (351 nm), frequency-multiplied Nd: YAG laser with wavelengths of 355 nm (frequency tripled) or 265 nm (frequency quadrupled). Nd: YAG lasers (1064 or 532 nm) and CO ₂ lasers are particularly preferably used. The energy densities of the lasers used are generally in the range from 0.3 mJ / cm ² to 50 J / cm ² , preferably 0.3 mJ / cm ² to 10 J / cm ² .

An Nd: YAG laser, Nd-V0 ₄ or C0 ₂ laser in different laser wavelengths, 1064 nm, 532 nm or 808-980 nm, is preferably used for the inscription. Marking is possible both in continuous cw mode (continuous wave) and in pulse mode. The suitable power spectrum of the marking laser comprises 2 to 100 watts, the pulse frequency is preferably in the range of 1 to 100 Hz.

Corresponding lasers that can be used in the method according to the invention are commercially available.

The inscriptions of plastics according to the invention can be used wherever plastics have previously been inscribed using printing, embossing or engraving processes or wherever no or no color-fast and permanent inscription / marking or only inscription / marking using laser-sensitive materials Pigments in the plastic itself was possible. This applies to linear or thermolabile cross-linked plastics, e.g. Polyolefins, vinyl polymers, polyamides, polyesters, polyacetals, polycarbonates, partly also polyurethanes and ionomers.

The advantages of the type of labeling according to the invention are color fastness, permanence and flexibility / individuality, i.e. Labeling can be done without a mask, cliché or stamp specification.

Plastics of any kind and shape, e.g. ^• in the packaging industry (batch number, shelf life, manufacturing data, information)

• in the security area (tamper-proof coding and identification) ^« in the automotive and aircraft industries (cables, plugs, switches, containers, functional parts, hoses, lids, handles, levers, etc.)

• in medical technology (devices, instruments, implants)

• in agriculture (animal ear tag marking) • < ⁿ of electrical engineering / electronics (cables, plugs, switches, functional parts, type plates, rating plates)

• Decorative area (logos, type designation for devices of all kinds, containers, toys, tools, individual markings)

marked and / or labeled.

The invention also relates to plastics which have been marked or labeled in color by the process according to the invention and whose marking has been sealed.

The following examples are intended to illustrate the invention without, however, limiting it. The percentages given are percentages by weight.

EXEMPLARY EMBODIMENTS

Depending on the layer thickness, the individual layer systems are applied with a squeegee or an engraving roller in gravure printing or with screen printing to the polyester carrier film or the previous layer and dried.

Example 1: Production of an energy absorber layer (2)

18.5 g ethyl acetate 1.5 g nitrocellulose 2.0 g Sn (Sb) 0 ₂ (d ₅₀ value <1.1 μm) (Du Pont) Nitrocellulose is dissolved in the ethyl acetate solvent and stirred well (Ultrathurax, 2000 rpm). The energy absorber Sb-doped Sn0 _{2 is then} stirred in and a homogeneous paste is produced. The amount of energy absorber depends on the energy absorption of the colorant and on the plastic to be labeled and must be adjusted accordingly.

Example 2: Production of an energy absorber layer (2)

18.5 g of ethyl acetate 1.5 g of nitrocellulose 2.0 g of carbon black (special black 6 from Degussa) (d ₅₀ value <17 nm)

Processing is carried out analogously to Example 1. Gas black is used as the absorber.

Example 3: Production of an energy absorber layer (7)

For carrier films (7) with already incorporated energy absorbers, polyethylene, polypropylene, PET flat films or composites are preferably extruded or blown from these, which have an effective energy absorber content, e.g. contain a soot content of 1 - 10%.

Example 4: Production of a separation layer (3)

19.9 g toluene 0.1 g ester wax

The PE wax is dissolved in toluene and stirred well.

Example 5: Preparation of a sealing layer (4) 8.0 g of methyl ethyl ketone 4.6 g of toluene 2.0 g of cyclohexanone 3.9 g PMMA (T _g : 122 ° C) (Degussa) 1.5 g PE wax

The PE wax and PMMA are dissolved in the solvent mixture and homogenized with a dissolver.

Example 6: Preparation of a sealing layer (4) 8.0 g xylene 4.0 g polystyrene 2.0 g PE wax

The PE wax and polystyrene are dissolved in xylene and homogenized with a dissolver.

Example 7: Production of a sealing layer (4)

40.0 g of n-butyl acetate

10.0 g polystyrene 0.5 g ethyl cellulose 0.5 g UV stabilizer

Ethyl cellulose, polystyrene and UV stabilizer are dissolved in n-butyl acetate and homogenized with a dissolver.

Example 8: Production of a writing medium containing Poivmer (5)

20.0 g ethyl acetate 2.0 g nitrocellulose 6.0 g polypropylene powder (d ₅₀ <50 mm) (e.g. Coathylene PB 0580, Du Pont) 2.0 g Cu phthalocyanine 1.0 g UV stabilizer ( benzotriazole) The nitrocellulose is dissolved in the ethyl acetate solvent and stirred well. The polypropylene powder, the colorant copper phthalocyanine and the UV stabilizer are then stirred in and a homogeneous paste is produced. If necessary, a 3-roller mill is used to improve paste homogeneity.

The paste is e.g. mounted on a squeegee on polyester films and dried.

Example 9: Production of a writing medium containing Poivmer (5)

25.0 g methyl ethyl ketone

34.0 g toluene

12.0 g PVC / PVAc copolymer

16.0 g polyurethane 0.5 g titanium oxide

Processing is carried out analogously to Example 8. Titanium dioxide is used as the colorant.

Example 10: Production of a writing medium containing Poivmer (5)

35.0 g n-butyl acetate 6.0 g polystyrene 2.0 g nitrocellulose 2.0 g Cu phthalocyanine

Processing is carried out analogously to Example 8. Cu phthalocyanine is used as the colorant.

Example 11: Production of a layer (8) from labeling medium (5) and energy absorber (2)

20.0 g ethyl acetate 2.0 g nitrocellulose 6.0 g irgazine red 1.2 g Sn (Sb) 0 ₂

Processing is carried out analogously to Example 7. Irgazine red is used as the colorant and Sn (Sb) 0 _{2 is} used as the absorber.

Example 12: Marking attempts and results

Nd-YV0 ₄ , 20 W output power, Nd-YV0 ₄ , 10 W output power, 1064 nm, 100 kHz pulse frequency 1064 nm, 50 kHz pulse frequency

Nd-YV0 ₄ , 6 W output power, Nd: YAG, 10 W output power,

532 nm, 50 - 60 kHz pulse frequency 1064 nm, 50 - 60 kHz pulse frequency

Example 13: Comparison of markings with and without sealing with regard to the influence on bleeding / efflorescence

Marking without sealing Bleeding on film that was in contact with the marking after bleeding

Marking with sealing no bleeding noticeable

Claims

claims

1. A method for permanent and abrasion-resistant colored labeling and / or marking of plastics, characterized in that the bleeding or blooming of the colorants and / or absorbers in the plastic is prevented by the areas labeled by a laser during the labeling process or immediately thereafter sealed with a transparent polymer.

2. A method for permanent and abrasion-resistant colored labeling and / or marking of plastics according to claim 1, characterized in that the polymer has a glass transition temperature of> 90 ° C.

3. A method for permanent and abrasion-resistant colored labeling and / or marking of plastics according to claim 1 or 2, characterized in that the sealing layer consists of the polymers of styrene, vinyl chloride, methyl methacrylate or hydroxy-functional acrylates, polyvinyl fluoride.

4. A method for permanent and abrasion-resistant colored labeling and / or marking of plastics according to one of claims 1 to 3, characterized in that the polymer layer has thicknesses of 1 -10 microns.

5. A method for permanent and abrasion-resistant colored labeling and / or marking of plastics according to one of claims 1 to 4, characterized in that the marking is carried out by an indirect labeling process.

6. A method for permanent and abrasion-resistant colored labeling and / or marking of plastics according to one of claims 1 to 5, characterized in that the labeling is done with a laser and the sealing in one step.

7. The method for permanent and abrasion-resistant colored labeling and / or marking of plastics according to one of claims 1 to 5, characterized in that in a 2-step process, only the labeling with a laser and immediately afterwards in a second step, the sealing of the labeled places.

8. A method for permanent and abrasion-resistant colored labeling and / or marking of plastics according to one of claims 1 to 6, characterized in that a layer system is used which consists of at least three superimposed layers, the first layer being a carrier film which is permeable to laser light , to which the laser light-sensitive energy absorber layer is applied or into which the energy absorber is incorporated, then the separating layer and the sealing layer and, as the last layer, the labeling medium containing colorant and possibly polymer component or a labeling medium already containing the sealing polymer, the labeling medium being influenced is introduced into the plastic surface by laser light during the lettering / marking.

G. Method for permanent and abrasion-resistant colored labeling and / or marking of plastics according to claim 7, characterized in that for the lettering a layer system consisting of a laser light-permeable carrier film and the energy absorber layer and the labeling medium as separate layers or a layer system consisting of carrier film and a layer consisting of a mixture of labeling medium and energy absorber or a layer system consisting of a carrier film, into which the energy absorber is incorporated and uses the labeling medium, marked with a laser, the labeling medium being transferred to the softened plastic and the sealing being carried out in a second step with a layer system consisting of a laser light-permeable carrier layer, a laser-sensitive absorber layer or a carrier film into which the energy absorber is incorporated, a separating layer and a seal ngsschicht and irradiated with a laser, the necessary energy is transferred via the energy absorber layer to the separating layer, which softens and thus transfers the sealing layer to the plastic.

10. A method for permanent and abrasion-resistant colored lettering and / or marking of plastics according to one of claims 1 to 6, characterized in that a layer system is used which consists of at least three superimposed layers, the first layer being a laser light-transparent and self Absorbent carrier film is used, to which the separating layer and the sealing layer and, as the last layer, the labeling medium containing colorant and possibly polymer component or a labeling medium already containing the sealing polymer is applied, the labeling medium under the action of laser light during the labeling / marking in the plastic surface is introduced.

11. The method for permanent and abrasion-resistant colored lettering and / or marking of plastics according to claim 7, characterized in that for the lettering a layer system consisting of a laser light-permeable and self-absorbing carrier film and a layer consisting of a mixture of the labeling medium and energy absorber or a layer system consisting of a carrier film, into which the energy absorber is incorporated and which uses the labeling medium, marked with a laser, the labeling medium passing over to the softened plastic and the sealing being carried out in a second step with a layer system consisting of a laser light-permeable carrier layer , a laser-sensitive absorber layer or a carrier film, into which the energy absorber is incorporated, a separating layer and a sealing layer and irradiated with a laser, the necessary energy via the energy absorber layer t is transferred to the separating layer, which softens and thus transfers the sealing layer to the plastic.

2. Plastics which have a sealed marking and / or lettering by the method according to one of claims 1 to 11.