TWI405809B - Resin composition for a white laser marking - Google Patents

Abstract

PURPOSE: A resin composition for white laser marking is provided to enable white marking with excellent whiteness on the surface of plastic molding products by laser irradiation. CONSTITUTION: A resin composition for white laser marking includes, based on 100.0 parts by weight of a thermoplastic resin or thermosetting resin, or their mixed resin, 0.01~5 parts by weight of black pigment, and 0.05~40 parts by weight of alkali metal compound. The black pigment is one kind selected from carbon black, titanium black, furnace black, acetylene black, lamp black, aniline black, and sulfur black.

Description

Resin composition for white laser marking

This invention relates to a resin composition for white laser marking that exhibits excellent white marking clarity and whiteness by laser beam radiation.

There are several conventional techniques for marking patterns, words, figures, images, or the like on molded articles made of plastic materials, such as pad printing, dip printing, laser marking, and the like. Among these technologies, laser marking has received attention in recent years, and because of its superiority in environment, energy, durability, economy, and design, it is widely used in electrical and electronic products, especially keyboard key surfaces and vehicle interior parts. Printed words. White laser marking on a black surface of a molded article composed of a resin composition containing only carbon black as an additive causes poor whiteness and appearance, and thus its use is extremely limited. Further, white laser marking exhibiting insufficient whiteness and unevenness mark on a molded article composed of a conventional resin composition mixed with a known polyfluorene oxide, metal, titanium oxide, mica and the like. These shortcomings limit their application in various fields.

It is an object of the present invention to provide a resin composition which produces excellent whiteness of marking on the surface of a molded article by laser beam irradiation and produces a clear white mark when marked with various types of laser devices.

The resin composition for white laser marking of the present invention is characterized by comprising 0.01 to 5 parts by weight of a black pigment and 0.05 to 40 parts by weight of an alkali metal compound per 100 parts by weight of the thermoplastic or thermosetting resin or a mixture thereof (based on the weight of the alkali metal) ).

As the thermoplastic resin used in the resin composition of the present invention, mention may be made of polyethylene, polypropylene (PP), polyester, polyphenylene sulfide, polycarbonate (PC), modified polyphenylene ether (mPPE), Polystyrene, high impact polystyrene (HIPS), acrylonitrile butadiene styrene (ABS), polybutylene terephthalate (PBT), polymethyl methacrylate (PMMA) resin, poly Acetal, polyurethane, unsaturated polyester, polyphenylene ether, acrylic resin, various elastomers (including natural rubber, synthetic rubber, and thermoplastic elastomer). As the thermosetting resin, a urea resin, a phenol resin, an epoxy resin, and the like can be mentioned. Mixtures of the above-listed resins and copolymerized resins can also be used in the present invention. However, the type of the resin is not particularly limited to the resins listed above, and other resins can be used in the present invention.

As the black pigment used in the resin composition of the present invention, carbon black, titanium black, furnace black, acetylene black, lamp black, aniline black, and sulfur black may be used singly or as a mixture of two or more substances. use. In particular, it is preferred to use a pigment formed of carbon particles, such as carbon black. The average particle diameter of the black pigment is preferably from 10 to 100 nm and more preferably from 30 to 70 nm. If the average particle diameter of the black pigment is out of the range, the whiteness of the laser mark may be undesirably deteriorated. The content of the black pigment is preferably from 0.01 to 5 parts by weight, and more preferably from 0.01 to 2 parts by weight. If the content of the black pigment is more than 5 parts by weight, the whiteness is deteriorated due to the shielding effect on the radiation of the laser beam, the screen The masking effect blocks the irradiated laser beam from penetrating deep into the surface. If the content is less than 0.01 parts by weight, the contrast becomes weak, resulting in deterioration of sharpness, which is also undesirable.

The alkali metal compound in the resin composition of the present invention is used as a catalyst for whiteness. The alkali metal compound significantly promotes the decomposition and evaporation of the black pigment after the laser beam is irradiated, and at the same time converts the energy absorbed by the black pigment into a hot form. These reactions improve the melting and foaming characteristics of the resin, thereby further enhancing whiteness and sharpness.

The metal element of the alkali metal compound may include sodium, potassium, and the like. Preferable examples of the alkali metal compound include potassium hydroxide, potassium citrate, sodium hydroxide, sodium acetate, and the like. These compounds may be used singly or in the form of a mixture of two or more substances. The alkali metal compound is contained in an amount of from 0.05 to 40 parts by weight, preferably from 0.1 to 20 parts by weight, based on the weight of the alkali metal. If the content of the alkali metal compound is less than 0.05 parts by weight based on the weight of the alkali metal, the marking property is lowered, resulting in deterioration of whiteness. If it is more than 40 parts by weight, the whiteness is undesirably deteriorated by carbonization, but the marking characteristics are improved.

Various additives which are generally used for improving the physical properties of the components, such as a resin stabilizer, a nucleating agent, a plasticizer, a flame retardant, a slip agent, may be incorporated into the resin composition of the present invention either singly or in a mixture. Antibacterial agents, fillers (such as ceria, talc, fiberglass, mica, calcium citrate, calcium carbonate, barium sulfate and the like). By adding such additives, durability and wear resistance can be improved after laser marking.

The resin composition of the present invention can be obtained by using a Hansen mixer (Hensel A mixer, a Banbury mixer, a kneader, an extruder, a ball mill, a continuous parallel mixer, a mortar and the like are kneaded and then extruded to prepare a mixture. The kneading method is not particularly limited as long as the black pigment and the alkali metal compound can be well dispersed, and various kneading methods such as a method of adding an alkali metal compound to a resin and a black pigment, fully grinding a black pigment, and an alkali metal compound can be used. Further, a method of kneading the resin with a resin or a method of kneading the alkali metal compound with a black pigment using a solvent is used.

In the preparation of the resin composition of the present invention, in order to improve the dispersion of the black pigment and the alkali metal compound, it is preferred to add a dispersing agent during the kneading. Although the type of the dispersant is not particularly limited, a fatty acid compound can be preferably used. As the fatty acid compound, there may be mentioned saturated or unsaturated C2 to C32 fatty acids or derivatives thereof, including salts, esters, guanamines and the like. Preferred embodiments may include: higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linoleic acid and the like; salts of higher fatty acids such as zinc laurate Calcium stearate, zinc stearate, sodium oleate and the like; and guanamines of higher fatty acids such as ethylene bis-stearamide, lauryl decylamine and the like. In order to increase the whiteness of the laser mark, the dispersant is preferably added in an amount of 0.002 to 10 parts by weight, particularly 0.01 to 5 parts by weight, per 100 parts by weight of the resin composition.

The method of forming the molded article of the resin composition of the present invention is not particularly limited, and injection molding, blow molding, rotational molding, and other well-known molding methods can be used.

The laser beam for marking on the molded article composed of the resin composition of the present invention is not particularly limited, and any of a gas laser, a semiconductor laser, a excimer laser, and the like can be used. It is preferably a laser having a wavelength range absorbed by carbon black, such as a Nd:YAG, Nd:YVO ₄ laser. A laser in the form of a lamp, a diode, or a fiber can be used. Compared to lamp lasers, diodes and fiber lasers are better due to their excellent whiteness.

With the resin composition of the present invention, a white mark having excellent whiteness and sharpness can be obtained on the surface of the molded article by a white laser mark.

The invention can be further understood in detail by reference to the following examples. However, the examples are merely illustrative of the invention and are not intended to limit the scope of the invention.

Examples and comparative examples

The resin composition was prepared by blending the components of the following Table 1. Each of the prepared resin compositions was extruded through a twin-screw extruder at 210 ° C, and injection molded to produce a flat sheet sample of a size of 100 mm × 100 mm × 2 mm. A 40 mm x 40 mm square was marked on the surface of the sample by using a Nd/YAG laser (Falcon). The whiteness (W1) and brightness (L) of each mark are then evaluated with a colorimeter and rated using a 5-point grading system, where a value of 1 refers to the best definition and whiteness, and a value of 5 refers to the minimum definition. And whiteness. The classification results are also shown in Table 1 below.

As shown in Tables 1 to 3, it was found that the grade of the laser marking property of the resin composition prepared by the embodiment of the present invention was significantly superior to that of the comparative example.

Claims (3)

A resin composition for laser marking comprising a thermoplastic or thermosetting resin or a mixture thereof, and 0.01 to 5 parts by weight of a black pigment and 0.05 to 40 parts by weight of an alkali metal compound per 100 parts by weight of the resin, to which the alkali metal The alkali metal compound is selected from the group consisting of sodium hydroxide, sodium acetate, potassium hydroxide, and potassium citrate. The resin composition for laser marking according to claim 1, wherein the thermoplastic resin is selected from the group consisting of polyethylene, polypropylene, polyester, polyphenylene sulfide, polycarbonate, and modified Polyphenylene ether, polystyrene, high impact polystyrene, acrylonitrile butadiene styrene, polybutylene terephthalate, polymethyl methacrylate resin, polyacetal, polyaminocarboxylic acid An ester, an unsaturated polyester, a polyphenylene ether, an acrylic resin, and an elastomer, and the thermosetting resin is selected from the group consisting of urea resin, phenol resin, and epoxy resin. The resin composition for laser marking according to claim 1, wherein the black pigment is at least one selected from the group consisting of carbon black, titanium black, furnace black, acetylene black, lamp black, and aniline. Black and sulfur black.