KR19990028386A - Use for the generation of high contrast optical information of polymer molding compositions that cause partial discoloration by laser energy - Google Patents

Abstract

The present invention relates in particular to the use of polymer molding compositions for causing partial discoloration using laser energy to generate high contrast optical information such as letters, numbers, patterns and / or images.

Description

Use for the generation of high contrast optical information of polymer molding compositions that cause partial discoloration by laser energy

The use of laser markers in plastic moldings for labeling and decorative purposes is becoming increasingly important to represent patterns, letters, numbers and / or images. Laser marking offers additional flexibility in the form, size and design of the text, regardless of the size of the batch, with economical advantages over conventional marking processes. The display of electrical / electronic components, keytops, housings and identification documents is a traditional laser marking application.

The following are the laser marking possibilities already known for plastic labeling.

1. a dark mark on a light background

The polymer matrix is colored with light colorants, ie pigments or dyes. The energy delivered by the laser during laser marking is absorbed, resulting in partial carbolation of the polymer matrix / colorant. This darkens the photopolymer matrix. These properties are limited to polymers that tend to carbohydrate.

The contrast ratios obtained in this way are inadequate in various fields. EP 0 190 997 describes the addition of colorants which absorb and discolor laser energy. Thus polybutylene terephthalate is colored red using, for example, iron oxide. Laser marking causes dark markings to appear on a red background. The contrast ratio proved to be insufficient.

2. Bright marks on dark background

Polymers, colorants or additives, which tend to foam by absorbing laser energy, have proved useful in this type of marking. Firing causes bright recordings to appear on the dark background. The contrast ratios obtained are insufficient for various applications.

The present invention relates to a polymer molding composition which, when absorbing laser energy, produces a bright indication with a high ratio on a dark background.

It has been surprisingly found that when pulverized carbon black is used in a polymer matrix, bright marks can be obtained on dark backgrounds by laser energy absorption. Different degrees of intermediate brightness can be obtained by varying the laser energy.

The present invention uses a laser marker to form a light or gray mark on a dark background, (A) polyamide, polyolefin, ABS type graft polymer, polyacrylate, polymethacrylate, or polycarbonate, ABS 99.7 to 50 parts by weight of a polymer selected from the group of the type graft polymer and optionally a copolymer, (B) 0.03 to 0.5 parts by weight carbon black, (C) 0 to 50 parts by weight reinforcement, (D) elastomer modifier 0 A laser marking of a polymer molding composition comprising from 20 parts by weight to 20 parts by weight, (E) 0 to 55 parts by weight of a flame retardant, and (F) 0 to 2 parts by weight of a processing aid additive, to provide a bright or gray display on a dark background. to provide.

The present invention further provides for the use of colored polymers for producing molded articles that can be marked, labeled or displayed using a laser marker.

The polymer molding compositions used according to the invention can be made with conventional commercial single and twin-screw extruders. Carbon black may be commercially available in the form of pigment concentrates. Conventional commercial injection molding machines can be used to make moldings.

Suitable thermoplastic polyamides according to the invention are generally aliphatic polyamides or polyamides having predominantly aliphatic segments. Polyamide 6 or polyamide 66 or polyamide 6 with diamines (preferably C ₄ -C ₁₆ , in particular C ₄ -C ₈ -alkylene diamines) and dicarboxylic acids (preferably C ₄ -C ₁₂ , especially 66. Copolyamide of C ₄ -C ₈ -alkylene dicarboxylic acid) or polyamide having a maximum comonomer ratio of 20% by weight.

The polyolefins according to the invention can be obtained by conventional methods, for example radical polymerization, and have aliphatic unsaturated hydrocarbons such as ethylene, propylene, having an average molecular weight M _w (measured by gel chromatography) of 5,000 to 30,000, Polymer of butylene or isobutylene. Each high pressure polyolefin and low pressure polyolefin can be used. Unsaturated hydrocarbons can be copolymerized in a known manner with various vinyl monomers, for example vinyl acetate, acrylic acid or acrylates and the maximum proportion of vinyl monomers is 30% by weight, preferably 25% by weight or less. Polyethylene and polypropylene are preferred.

The polymer of (meth) acrylate alkyl used is preferably C ₁ -C ₁₈ -alkyl (meth) acrylate.

Acrylate that can be used is generally C ₁ -C ₁₈ -alkyl esters such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, pentyl, Hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, lauryl or stearyl acrylate, preferably methyl acrylate, n-butyl acrylate and 2-ethylhexyl acrylate, and mixtures of these monomers .

Methacrylates that can be used are generally C ₁ -C ₁₈ -alkyl esters, for example methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, tert-butyl, pentyl , Hexyl, heptyl, octyl, 2-ethylhexyl, nonyl, decyl, lauryl or stearyl acrylate, preferably methyl methacrylate, and mixtures of these monomers.

Suitable thermoplastic aromatic polycarbonates according to the invention, which are mixed with graft polymers and optionally copolymers, are those based on diphenols of the formula (I).

Where

A represents a single bond, C ₁ -C ₅ -alkylene, C ₂ -C ₅ -alkylidene or C ₅ -C ₆ -cycloalkylidene group, -S- or -SO _2- .

Suitable diphenols of formula (I) are, for example, hydroquinone, resorcinol, 4,4'-dihydroxydiphenol, 2,2-bis- (4-hydroxyphenyl) -propane, 2, 4-bis- (4-hydroxyphenyl) -2-methylbutane or 1,1-bis- (4-hydroxyphenyl) -cyclohexane.

Preferred diphenols of formula (I) are 2,2-bis- (4-hydroxyphenyl) -propane and 1,1-bis- (4-hydroxyphenyl) -cyclohexane.

Diphenols of formula (I) are known in the literature or can be prepared according to methods known from the literature.

The preparation of suitable polycarbonates according to the invention is known in the literature and can be carried out with phosgene, for example by a phase boundary process or a process in a homogeneous phase (so-called pyridine process). In this method, the specific molecular weight required is prepared by known methods using appropriate amounts of known chain terminators. Suitable chain terminators are, for example, monophenols such as phenol itself, p-cresol, p-tert-butylphenol and p-isooctylphenol.

The average molecular weight of the suitable chain terminator according to the invention (M _w , for example measured by ultracentrifuge or by measuring scattered light) is 10,000 to 200,000, preferably 20,000 to 80,000.

Suitable polycarbonates according to the invention are homopolycarbonates or copolycarbonates.

Suitable polycarbonates according to the invention can be branched by known methods and more precisely 0.05 to 2.0 mole% of compounds having at least trifunctional compounds, such as compounds having at least three phenol groups, relative to the total amount of diphenols used. Can be mixed.

Graft polymers that can be used are ABS polymers, by themselves or in admixture with polycarbonates.

Graft Polymers

(K.1.1) 50 to 95 parts by weight, preferably 60, of styrene, α-methylstyrene, halogen or methyl ring-substituted styrene, C ₁ -C ₈ -alkyl methacrylates, especially methyl acrylate or mixtures of these compounds To 90 parts by weight and

(K.2) 5 to 95 parts by weight, preferably 20 to 70 parts by weight, of a polymer based on a diene having a glass transition temperature of less than -10 ° C.

(K.1.2) acrylonitrile, methacrylonitrile, C ₁ -C ₈ -alkyl methacrylates, in particular methyl methacrylate, C ₁ -C ₈ -alkyl acrylates, especially methyl acrylate, maleic anhydride, C ₁ -C ₄ -alkyl or phenyl N-substituted maleimide or a mixture of these compounds 5 to 50, preferably 10 to 40 parts by weight of the mixture.

Preferred graft substrates are polybutadiene, butadiene / styrene copolymers and acrylate rubbers. The graft substrate is particulate and generally has an average particle diameter of 0.05 to 5 μm, preferably 0.1 to 0.8 μm.

Graft bases are esters of acrylic or methacrylic acid having 1 to 4 carbon atoms in the alcohol component, in addition to other ethylenically unsaturated monomers, such as butadiene (e.g. methyl acrylate, Ethyl acrylate, methyl methacrylate, ethyl methacrylate), vinyl esters, and / or vinyl ether groups. Preferred graft substrates consist of pure polybutadiene.

Preferred graft polymers are, for example, polybutadiene, butadiene / styrene copolymers grafted with styrene and / or acrylonitrile and / or alkyl (meth) acrylates, ie DE-OS 1 694 173 ( = Copolymers of the type described in US-PS No. 3 564 077); Acrylate or methacrylate, vinyl acetate, acrylonitrile, styrene and / or alkylstyrene, as described, for example, in DE-OS 2 348 377 (= US-PS 3 919 353). Substrates (K.2) such as polybutadiene, butadiene / styrene or butadiene / acrylonitrile copolymers, polyisobutene or polyisoprene grafted with.

Thus, as is known, during the graft reaction, it is understood that the graft monomers are not completely grafted onto the graft substrate and that the graft polymers according to the invention also comprise these products obtained by polymerizing the graft monomer in the presence of the graft substrate.

The average particle size d ₅₀ is the diameter at which 50% by weight of the particles are present in and below each, respectively. This can be measured by ultracentrifugation measurement (W. Scholtan, H. Lange, Kollid, Z. und Z. Polymere 250 (1972), 782-796).

The mixture of the polycarbonate, the graft polymer of the ABS type and optionally the copolymer is 50 to 96.5 parts by weight of polycarbonate, especially 60 to 96 parts by weight, up to 25 parts by weight of the graft polymer of the ABS type, in particular 3 to 15 parts by weight. Parts and optionally 50 to 95% by weight of styrene, α-methylstyrene, ring-substituted styrene, methyl methacrylate or mixtures thereof and 50 to 5% by weight of (meth) acrylonitrile, methyl methacrylate or mixtures thereof 40 parts by weight or less, in particular 20 parts by weight or less.

Finely divided carbon black is suitable as carbon black B) in the molding composition used according to the present invention. Carbon black is concentrated as pure carbon black (particle size 13-20 nm) in bead foams or for example Microlen Schwarz B ™ from Ciba geigy (Basle). It can be used as water.

Conventional commercial glass and / or inorganic fibers and / or inorganic fillers such as kaolin, ulastonite, talc or whistle up to 50% by weight are used as reinforcement C in the molding compositions used according to the invention. do.

Conventional commercial EP (D) M (ethylene-propylene-diene) rubbers, graft rubbers based on butadiene styrene acrylonitrile (see above), acrylate rubbers, polyurethanes with or without functional coupling groups or EVA Up to 20% by weight copolymer is used as the elastomeric modifier D) according to the invention.

Up to 55% by weight of conventional commercial organic compounds or synergistic halogen compounds or conventional commercial organic nitrogen compounds or organic / inorganic phosphorus compounds as flame retardant E) (EP-A 345 522, DE-OS agent). 43 28 656). Inorganic flame retardants such as magnesium hydroxide or hydrated calcium carbonate may also be used.

Processing aid additive E) comprises up to 2% by weight of conventional commercial lubricants, stabilizers, mold release agents and nucleating agents.

Conventional commercial laser systems, preferably Nd-YAG solid systems, may be used as the energy source. The wavelength may be 193 to 10,600 nm, preferably 1,064 nm.

Molding compositions used in accordance with the present invention employ optical energy in the form of patterns, graphics, numbers, letters, letter marks, images (e.g., ID photos, portraits, photographs) using laser energy, for example laser markers. Can be used to apply.

The image image can thus be transferred, for example, onto the molding composition used according to the invention.

The present invention relates in particular to the use of polymer molding compositions for causing partial discoloration using laser energy to produce high contrast optical information such as letters, numbers, patterns and / or images.

In this example the following materials were used.

Polyamide 6 = Durthan B 31 SK (trade name) of Bayer AG

Polyamide 6, glass fiber reinforced (30%) = Durer BKV 30 H (trade name) from Bayer AG

Glass fiber reinforced (30%) polyamide 6 = Durertan BKV 130 ™ from Bayer AG, with modified impact strength

Glass fiber reinforced (30%) polyamide 6 with Dured RM KU 2-2501 (trade name) from Bayer AG

Polyamide 6 reinforced with glass fibers and glass beads 6 = Durertan BG 30X from Bayer AG

Partially aromatic polyamides = BG 30X ™ Durertan T 40 ™ from Bayer AG

ABS = Novodur P2H (trade name) from Bayer AG

ABS + polycarbonate = Bayblend FR90 ™ with flame retardant

PMMA = Plexiglas 7N (trade name) by Roem GmbH Darmstadt

Micron Schwartz B (trade name) carbon black / Shiba Guy

The dye was premixed with granules in a twin-screw mixer and extruded to granulate. The granules obtained were injection-molded to form slabs on an Aeburg injection-molding machine and marked using a FOBALLAS Nd-YAG laser.

White or gray marks were formed on the dark background depending on the laser beam energy intensity. All signs and symbols written are distinguished by high contrast and different gray medium brightness.

Yes One 2 3 4 5 6 Duretan B 31 SK 99.8 Duretan T 40 % 99.8 Novodur P 2H % 99.8 Bibleland FR 90 % 99.8 Plexiglass 7N % 99.8 Hostalene PP % 99.8 Microrollen Schwartz B % 0.2 0.2 0.2 0.2 0.2 0.2 prepare Very good Very good Very good Very good Very good Very good

Yes 7 8 9 10 Duretan BKV 30 H 99.7 Duretan BKV 130 % 99.6 Duretan RM 2501 % 99.8 Duretan BG 30 X % 99.7 Microrollen Schwartz B ^* % 0.3 0.4 0.2 0.3 prepare Very good Very good Very good Very good ^* 50% -concentration

Claims (10)

(A) 99.7 to 50 parts by weight of a polymer selected from the group of polyamides, polyolefins, ABS type graft polymers, polyacrylates, polymethacrylates, or polycarbonates, ABS type graft polymers and optionally mixtures of copolymers (B) 0.03 to 0.5 parts by weight of carbon black, (C) 0 to 50 parts by weight of reinforcing agent, (D) 0 to 20 parts by weight of elastomeric modifier, (E) 0 to 55 parts by weight of flame retardant, (F) processing aid additive Use for making light or gray marks on a dark background by laser marking of a polymer molding composition comprising 0 to 2 parts by weight. Use according to claim 1, characterized in that it comprises polyamide as polymer. The use according to claim 1, wherein carbon black is used as 0.03 to 3 parts by weight. Use according to claim 1, characterized in that it contains 0 to 50 parts by weight of glass fiber, inorganic fiber or inorganic filler as reinforcing agent. Use according to claim 1, characterized in that it contains 0 to 40 parts by weight of EPM, EDPM, acrylate rubber or EVA copolymer as elastomer modifier. The use according to claim 1, which comprises 0 to 55 parts by weight of a conventional commercial flame retardant based on an organic compound of halogen, nitrogen or phosphorus or magnesium hydroxide or calcium carbonate magnesium as a flame retardant. Use according to claim 1, which contains 0 to 2% of a lubricant, stabilizer, mold release agent and nucleating agent as processing aid additives. 2. Use according to claim 1 for applying optical information by laser energy. An image according to claims 1 and 8. Passport photos, portraits and photographs transcribed in accordance with claim 9.