JP4675682B2 - Thermoplastic resin composition for white marking - Google Patents

Description

  The present invention relates to a white marking thermoplastic resin composition capable of forming a white marking by irradiation with a laser beam, and more particularly to a white marking thermoplastic resin composition excellent in coloring property and stain resistance of a marking portion. The present invention also provides a white laser marking molded article composed of the white marking thermoplastic resin composition, a white marking method for irradiating the molded article with a laser beam to give white marking, and a laser beam applied to the molded article. It is related with the white mark formation molded object obtained by irradiating. The present invention further relates to a method for preventing fouling and / or abrasion of a marking portion of a white mark forming molded body on which white marking is applied.

  Laser-irradiated printing (laser marking) has become widespread as an alternative to printing and painting with ink. In the case of white laser marking among laser markings, the higher the contrast with respect to the dark background, the better the visibility and quality, so a marking with higher whiteness is required. In particular, as the application expands, not only the conventional dark color system but also a high contrast marking is required for various background colors.

  As a method for improving the whiteness, a method for increasing the laser absorption efficiency in order to sufficiently decompose and foam the resin with low energy has been proposed. For example, a method of adding a pearlescent pigment coated with mica, manganese violet, cobalt violet compound, or the like to a resin is known (for example, Patent Documents 1 and 2). However, the former method cannot be used when pearly luster is not required, and the latter method is problematic in practice because of concern about safety and environmental impact.

  On the other hand, when marking a resin molded body with white, even if the initial whiteness is satisfactory, the marking part may be soiled by hand dirt while using the product with the white mark. The problem that whiteness falls and a feeling of quality is impaired arises. In order to solve such a problem, it has been proposed to prevent the marking portion from being soiled by coating the marking portion or laminating a protective layer, but this is expensive and unrealistic.

JP-A-9-12776 JP-A-2-204888

An object of the present invention is to provide a white marking thermoplastic resin composition having excellent fouling resistance and abrasion resistance, a molded body composed of the resin composition, a method for applying white marking to the molded body, and the molded body. An object of the present invention is to provide a white mark forming molded body having a white mark on the surface.
Another object of the present invention is to provide a white marking thermoplastic resin composition having excellent initial whiteness, a molded article composed of the resin composition, a method for applying white marking to the molded article, and the molded article. An object of the present invention is to provide a white mark forming molded body having a white mark on the surface.
Still another object of the present invention is to provide a method for effectively preventing the contamination and / or abrasion of the marking portion of the white mark forming molded body on which white marking is applied.

  As a result of intensive studies, the present inventor has given white markings when a predetermined amount of an olefin polymer and a coloring material are blended with a resin containing at least a polymer containing a constituent monomer of an acrylic monomer. The present inventors have found that the marking portion is not easily soiled and is not easily worn even when the molded body is used for a long period of time.

That is, the present invention relates to 60 to 100 parts by weight of a copolymer (a-1) composed of (meth) acrylic acid C _1-18 alkyl ester, acrylonitrile, styrene and a rubber component, and a copolymer composed of acrylonitrile and styrene ( a-2) containing at least one selected from rubber-reinforced styrene-based resin consisting of 0 to 40 parts by weight [provided that (a-1) + (a-2) = 100 parts by weight] and polymethyl methacrylate The low viscosity olefin polymer (B1) having a viscosity (η) of 0.01 to 100 Pa · s in a rotary rheometer (230 ° C., shear rate 1 sec ⁻¹ ) 1 to 5 parts by weight and / or 0.1 to 1 part by weight of an olefin polymer (B2) having a viscosity (η) exceeding 100 Pa · s, and 0.0001 to 5 parts by weight of a coloring material (C) were blended. , Laser beam White markings provide white-marking thermoplastic resin composition capable upon irradiation.

In this rubber-reinforced styrene resin, the monomer composition of the copolymer (a-1) is preferably 40 to 60% by weight of (meth) acrylic acid C _1-18 alkyl ester, 3 to 14% by weight of acrylonitrile, Styrene is 12 to 25% by weight and rubber component is 6 to 24% by weight. The monomer composition of the copolymer (a-2) is preferably 10 to 26% by weight of acrylonitrile and 74 to 90% by weight of styrene. Moreover, as an average particle diameter of the rubber component of a copolymer (a-1), 150-800 nm is preferable. The ratio (former / latter) of the melt index (MI; 230 ° C., 5 kg) of the copolymer (a-1) and the melt index (MI; 230 ° C., 5 kg) of the copolymer (a-2) is: For example, the range is 1/200 to 1/2.

  As the low-viscosity olefin polymer (B1), for example, at least one selected from polyethylene wax and polypropylene wax can be used. In addition, as the olefin polymer (B2), for example, at least one selected from polyethylene and polypropylene can be used.

Colorant (C) preferably comprises dark color Pigments. The color material (C) may be carbon black having an average particle diameter of 10 to 90 nm.

The thermoplastic resin composition for white marking further contains 0.01 to 5 parts by weight of a saturated or unsaturated fatty acid having 12 to 30 carbon atoms or a derivative thereof with respect to 100 parts by weight of the thermoplastic resin composition. May be. A saturated or unsaturated fatty acid having 12 to 30 carbon atoms or a derivative thereof is preferably a metal salt of a saturated or unsaturated fatty acid having 12 to 30 carbon atoms .

  The present invention also provides a molded article capable of white marking comprising the above-described thermoplastic resin composition for white marking.

  The present invention further provides a white marking method in which white marking is performed by irradiating the molded body with a laser beam. The present invention further provides a white mark forming molded body in which white marking is applied to the molded body by irradiation with a laser beam.

The present invention further provides a molded article to be subjected to white marking, (meth) acrylic acid C _1-18 alkyl ester, acrylonitrile, styrene and a rubber component copolymer (a-1) 60 to 100 parts by weight, Copolymer comprising acrylonitrile and styrene (a-2) 0 to 40 parts by weight [provided that (a-1) + (a-2) = 100 parts by weight], rubber-reinforced styrene resin, and polymethyl methacrylate Low viscosity having a viscosity (η) of 0.01 to 100 Pa · s in a rotary rheometer (230 ° C., shear rate 1 sec ⁻¹ ) in 100 parts by weight of resin (A) containing at least one selected from 0.1 to 5 parts by weight of the olefin polymer (B1) and / or 0.1 to 1 part by weight of the olefin polymer (B2) having a viscosity (η) exceeding 100 Pa · s, and 0. 0001-5 A method for preventing fouling and / or abrasion of a marking portion of a white mark forming molded article obtained by applying white marking to a molded article to which the white marking is applied, by constituting with a thermoplastic resin composition in which an amount is blended I will provide a. In this specification, in addition to the above invention, 100 parts by weight of a resin (A) containing at least a polymer containing an acrylic monomer as a constituent monomer is added to a rotary rheometer (230 ° C., shear rate). 0.1 to 5 parts by weight of a low-viscosity olefin polymer (B1) having a viscosity (η) of 0.01 to 100 Pa · s at 1 sec ⁻¹ ) and / or an olefin having a viscosity (η) exceeding 100 Pa · s Also about the thermoplastic resin composition for white marking in which 0.1 to 1 part by weight of the polymer (B2) and 0.0001 to 5 parts by weight of the colorant (C) are blended and white marking can be performed by laser beam irradiation Describe.

  A product in which white marking is applied to a molded article composed of the thermoplastic resin composition for white marking of the present invention has excellent fouling resistance, is resistant to staining even after long-term use, and maintains the initial whiteness. Moreover, it is excellent in abrasion resistance. In addition, the initial whiteness is high, resulting in a high quality feeling.

[Resin A]
The resin (A) is not particularly limited as long as it contains at least a polymer containing an acrylic monomer as a constituent monomer (hereinafter sometimes simply referred to as “polymer A1”). Such a resin foams when irradiated with a laser beam and causes a white marking to appear on the surface of the molded product.

Acrylic monomers include (meth) acrylic acid, (meth) acrylic acid esters, and the like. Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, t-butyl (meth) acrylate, (meth) Hexyl acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tetradecyl (meth) acrylate, (meth ) (Meth) acrylic acid C _1-18 alkyl ester such as hexadecyl acrylate; (meth) acrylic acid cycloalkyl ester such as cyclohexyl (meth) acrylate; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate ; (Meth) acrylic acid such as benzyl (meth) acrylate Such as Lal kill ester, and the like. Among these, (meth) acrylic acid C _1-10 alkyl esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate [in particular, C _1-4 alkyl (meth) acrylate Ester] is preferred. Acrylic monomers may be used alone or in combination of two or more.

  The polymer A1 may contain a monomer other than the acrylic monomer as a constituent monomer. Such a monomer may be any monomer copolymerizable with an acrylic monomer. For example, a vinyl cyanide monomer, a styrene monomer, maleic anhydride, an imide monomer Examples include masses. By using these monomers (especially styrene monomers) as constituent monomers, it is possible to achieve white marking with a lower energy laser beam, as well as a remarkable marking acceleration effect, impact resistance, and moldability. The improvement effect is obtained.

  Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile. Examples of the styrenic monomer include styrene, alkyl-substituted styrene (for example, vinyltoluene such as o-methylstyrene, m-methylstyrene, and p-methylstyrene), and halogen-substituted styrene (for example, o-chlorostyrene, p- Chlorostyrene, o-bromostyrene, etc.), and α-alkyl-substituted styrenes substituted with an alkyl group at the α-position (for example, α-methylstyrene, α-ethylstyrene, etc.). Among these, styrene, vinyl toluene, α-methyl styrene and the like are particularly preferable. Examples of the imide monomer include N-alkylmaleimide (eg, N-methylmaleimide, N-ethylmaleimide, etc.), N-cycloalkylmaleimide (eg, N-cyclohexylmaleimide, etc.), N-arylmaleimide [eg, N -Phenylmaleimide, N- (2-methylphenyl) maleimide and the like] and the like.

  The polymer A1 may contain a rubber component as a constituent component. By including the rubber component in the polymer, the impact resistance of the molded product can be improved. Examples of the rubber component include polybutadiene, butadiene-styrene copolymer, polyisoprene, butadiene-acrylonitrile copolymer, isobutylene-isoprene copolymer, ethylene-propylene rubber, acrylic rubber, urethane rubber, silicone rubber, and butyl rubber. Can be mentioned. Of these, butadiene is particularly desirable. The rubber component can be contained in the polymer A1 by a blend method, copolymerization (graft copolymerization, block copolymerization) or the like. A rubber component contained in a polymer by a blending method is also referred to as a “copolymer” for convenience.

  The polymer A1 is preferably a polymer containing at least methyl methacrylate as a constituent monomer from the viewpoints of transparency, color developability, color sharpness, moldability, and the like. In such a polymer, the amount of methyl methacrylate used is preferably 20% by weight or more, more preferably 30% by weight or more, particularly preferably 30%, based on the total amount of monomers constituting the polymer A1. About 60% by weight.

Preferred polymers A1 include (i) a copolymer of (meth) acrylic acid C _1-18 alkyl ester (especially methyl methacrylate), acrylonitrile, styrene and a rubber component (eg butadiene), (ii) ethylene, (Meth) acrylic acid C _1-18 alkyl ester (particularly methyl methacrylate) and a copolymer of carbon monoxide, (iii) polymethyl methacrylate, and the like are included.

  The resin (A) may contain a polymer A2 other than the polymer A1 containing the acrylic monomer as a constituent monomer. Examples of such a polymer A2 include a styrene polymer containing a styrene monomer as a constituent monomer. Examples of the styrenic monomer include those exemplified above. The styrenic polymer may contain a monomer other than the styrenic monomer as a constituent monomer. Such a monomer may be any monomer that can be copolymerized with a styrene monomer, such as the vinyl cyanide monomer, maleic anhydride, and the imide monomer. Can be mentioned. The styrenic polymer may contain a rubber component as a constituent component. Examples of the rubber component include those exemplified above.

  Preferred polymers A2 include polystyrene, styrene-acrylonitrile copolymer (AS resin), styrene-butadiene copolymer, styrene-acrylonitrile-butadiene copolymer (ABS resin), α-methylstyrene-modified ABS resin, imide-modified ABS. Examples thereof include a resin, a styrene-maleic anhydride copolymer (SMA), a butadiene-acrylonitrile copolymer, and an acrylonitrile-ethylene-propylene-styrene copolymer (AES). Among these, a styrene-acrylonitrile copolymer is particularly preferable. By including a styrene-acrylonitrile copolymer (AS resin) in the resin (A), heat resistance, light resistance, oil resistance, mechanical strength, moldability, and the like are improved.

  The ratio of the polymer A1 containing the acrylic monomer as a constituent monomer in the resin (A) is, for example, 50% by weight or more, preferably 60% by weight or more, and more preferably 70% by weight or more.

As a typical example of the resin (A), (1) a copolymer (a) composed of (meth) acrylic acid C _1-18 alkyl ester (particularly methyl methacrylate), acrylonitrile, styrene and a rubber component (for example, butadiene) -1), (2) (meth) acrylic acid C _1-18 alkyl ester (particularly methyl methacrylate), acrylonitrile, styrene and a rubber component (for example, butadiene) (a-1), styrene- A blend with an acrylonitrile copolymer (AS resin) (a-2), (3) polymethyl methacrylate (a-3), etc. are mentioned.

As a particularly preferred resin (A), 60 to 100 parts by weight (preferably 70) of a copolymer (a-1) comprising (meth) acrylic acid C _1-18 alkyl ester, acrylonitrile, styrene and a rubber component (for example, butadiene). To 100 parts by weight) and a copolymer (a-2) consisting of acrylonitrile and styrene 0 to 40 parts by weight (preferably 0 to 30 parts by weight) [where (a-1) + (a-2) = 100 Rubber-reinforced styrene-based resin comprising [parts by weight]. When such a rubber-reinforced styrene-based resin is used as the resin (A), a molded product having a good balance of properties such as color developability, sharpness, moldability, mechanical strength, and impact resistance can be obtained.

In this rubber-reinforced styrene-based resin, the monomer composition of the copolymer (a-1) is (meth) acrylic acid C _1-18 alkyl ester 40 to 60% by weight (more preferably 45 to 60% by weight), Acrylonitrile 3-14% by weight (more preferably 4-12% by weight), Styrene 12-25% by weight (more preferably 14-23% by weight), Rubber component (eg butadiene) 6-24% by weight (more preferably 8 to 22% by weight). If the amount of the (meth) acrylic acid C _1-18 alkyl ester is too small, the color developability and the sharpness of the white color are liable to be lowered. If the amount of styrene is too small, the processability is liable to be lowered, and a rubber component (for example, If the amount of butadiene) is too small, the impact resistance tends to decrease.

  The monomer composition of the copolymer (a-2) is 10 to 26% by weight (more preferably 12 to 25% by weight) acrylonitrile, 74 to 90% by weight styrene (more preferably 7.5 to 88% by weight). It is. The styrene-acrylonitrile copolymer contains a small amount (for example, about 0 to 10% by weight, preferably about 1 to 6% by weight) of a structural unit corresponding to a polymerizable unsaturated carboxylic acid such as (meth) acrylic acid. May be.

  The average particle size of the rubber component of the copolymer (a-1) can be appropriately selected within a range that does not impair transparency, color developability, whiteness of marking, impact resistance, etc., but generally 150 to 800 nm, preferably 200-600 nm. If the average particle size is too small, the impact resistance tends to decrease, and if it is too large, the transparency and color developability tend to decrease.

  The ratio (former / latter) of the melt index (MI; 230 ° C., 5 kg) of the copolymer (a-1) to the melt index (MI; 230 ° C., 5 kg) of the copolymer (a-2) is, for example, 1 / 200 to 1/2, preferably in the range of 1/50 to 1/5. If this ratio is too small, the impact strength tends to decrease, and conversely if too large, the color developability tends to decrease.

[Low viscosity olefin polymer (B1), olefin polymer (B2)]
When a low-viscosity olefin polymer (B1) or olefin polymer (B2) is included in the white marking thermoplastic resin composition, foaming proceeds smoothly when the surface of the molded product is irradiated with a laser beam. Because it grows sufficiently, it produces a good color, and even if a product with a white marking is used for a long period of time, it is difficult to get dirty due to dirt, dust, etc., and it is difficult to wear. On the other hand, in the resin composition that does not contain the low-viscosity olefin polymer (B1) and olefin polymer (B2), foaming does not proceed sufficiently when the surface of the molded product is irradiated with a laser beam, or the generated foam layer is crushed. In other words, the surface of the raised foam layer has many irregularities, and the surface of the foamed layer is darkened.

The low-viscosity olefin polymer (B1) may be an olefin polymer having a viscosity (η) in the range of 0.01 to 100 Pa · s in a rotational rheometer (230 ° C., shear rate 1 sec ⁻¹ ). There are no particular limitations on the type of olefin, and any of olefinic waxes such as polyethylene wax and polypropylene wax may be used. Polyethylene wax includes low density homopolyethylene, low density polyethylene oxide, high density homopolyethylene, high density polyethylene oxide, ethylene-acrylic acid copolymer (acrylic acid-modified polyethylene) and maleic anhydride-ethylene copolymer (anhydrous maleic anhydride). Acid-modified polyethylene such as acid-modified polyethylene) and ethylene-vinyl acetate copolymer (vinyl acetate-modified polyethylene). Examples of the polypropylene wax include polypropylene, block polymers, and acid-modified polypropylene such as maleic anhydride-propylene copolymer (maleic anhydride-modified polypropylene).

When the viscosity (η) of the low-viscosity olefin polymer (B1) in a rotational rheometer (230 ° C., shear rate 1 sec ⁻¹ ) is lower than 0.01 Pa · s, the wear resistance effect is lowered, whereas 100 Pa -When it exceeds s, since compatibility with resin falls, the addition amount will be restrict | limited. The viscosity (η) is more preferably 0.05 to 20 Pa · s, and still more preferably 0.10 to 5.0 Pa · s.

The olefin polymer (B2) may be any olefin polymer having a viscosity (η) of more than 100 Pa · s in a rotational rheometer (230 ° C., shear rate 1 sec ⁻¹ ), such as polyethylene and polypropylene. Can be mentioned. The polyethylene may be any of low density polyethylene, linear low density polyethylene, high density polyethylene, and the like. The melting point of polyethylene is, for example, 100 to 140 ° C, preferably 105 to 135 ° C, and the glass transition temperature is, for example, -55 ° C to -15 ° C, preferably -50 ° C to -20 ° C. Polypropylene may be any of random type, block type, homo type and the like. The melt flow rate (MFR) (230 ° C., 2.16 kg load) of polypropylene is, for example, 0.1 to 80 g / 10 min, preferably 1 to 70 g / 10 min.

  The blending amount of the low-viscosity olefin polymer (B1) is 0.1 to 5 parts by weight with respect to 100 parts by weight of the resin (A) containing at least a polymer containing an acrylic monomer as a constituent monomer. The amount is preferably about 0.3 to 3 parts by weight. The blending amount of the olefin polymer (B2) is 0.1 to 1 part by weight with respect to 100 parts by weight of the resin (A) containing at least a polymer containing an acrylic monomer as a constituent monomer, preferably Is about 0.3 to 0.9 parts by weight. When the blending amount of the low viscosity olefin polymer (B1) or olefin polymer (B2) is too small, the fouling resistance and wear resistance of the white marking part of the molded product are low. Decrease, and appearance abnormalities easily occur.

[Coloring material (C)]
The color material (C) preferably contains at least an organic or inorganic dark dye or pigment. The dark-colored dye / pigment absorbs a laser beam (for example, a wavelength of 354 nm to 1064 nm), converts it into thermal energy, foams or crazes the resin, and acts to develop a white marking.

  Examples of the dark dyes include carbon black (acetylene black, lamp black, thermal black, furnace black, channel black, ketjen black, etc.), graphite, titanium black, black iron oxide, and the like. Among these, carbon black is preferable from the viewpoints of dispersibility, color developability, cost, and the like. The dark color pigments can be used alone or in combination of two or more.

  The average particle diameter of the dark dye / pigment can be appropriately selected from a wide range of, for example, 10 nm to 3 μm, preferably 10 nm to 1 μm. When the dark dye / pigment is carbon black, the average particle diameter is, for example, about 10 to 90 nm, preferably 12 to 70 nm, and more preferably about 17 to 50 nm (particularly 17 to 40 nm). If the particle size of the dark dye / pigment is too small, dispersion becomes difficult, and conversely if too large, the marking tends to be unclear.

  The amount of the dark dye / pigment used is, for example, 0.005 to 5 parts by weight, preferably 0.01 to 1 part by weight, and more preferably 0.05 to 0.5 parts by weight with respect to 100 parts by weight of the resin (A). About a part. If the amount of the dark-colored dye / pigment is too small, the conversion efficiency of the laser beam into heat is lowered and color development tends to be insufficient. Conversely, if the amount is too large, the marking becomes excessive and yellowing tends to occur.

  As the coloring material (C), dyes other than dark dyes can be used. Such a non-dark color dye / pigment may be either inorganic or organic. Examples of non-dark dyes include white pigments (eg, calcium carbonate, titanium oxide, zinc oxide, zinc sulfide, lithopone), yellow pigments (eg, cadmium yellow, yellow lead, titanium yellow, zinc chromate, ocher, yellow Iron oxide, etc.), red pigment (eg, red mouth pigment, amber, red iron oxide, cadmium red, red lead, etc.), blue pigment (eg, bitumen, ultramarine blue, cobalt blue, etc.), green pigment (eg, chrome green, etc.) Etc. Non-dark color dyes can be used alone or in combination of two or more.

  Among these, white dyes and pigments (for example, titanium oxide) that are inexpensive, excellent in hiding power and dispersibility, and capable of extremely clear white marking are preferable. The white dye / pigment is a combination of a dark dye and a white dye / pigment in order to increase the efficiency of conversion to heat by improving the absorption efficiency of the laser beam by the dark dye / pigment by scattering the laser beam. A white marking with very high whiteness is obtained. Further, by including a white dye / pigment, marking is possible even if the irradiation energy of the laser beam is lowered.

  The amount of the non-dark color dye / pigment used is, for example, 2 parts by weight or less (for example, 0.0001 to 2 parts by weight), preferably 1.5 parts by weight or less (for example, 0, for 100 parts by weight of resin (A) 0.01 to 1.5 parts by weight). If the amount of the non-dark color dye / pigment is too small, the effect of scattering the laser beam becomes poor. Conversely, if the amount is too large, the marking color becomes tinged with the hue of the dye / pigment.

  The total amount of the color material (C) is generally 0.0001 to 5 parts by weight, preferably 0.01 to 4 parts by weight, and more preferably about 0.1 to 3 parts by weight with respect to 100 parts by weight of the resin (A). It is.

  The thermoplastic resin composition for white marking of the present invention may contain a higher fatty acid or a derivative thereof. When a higher fatty acid or a derivative thereof is blended, the dispersibility of the color material such as carbon black is improved and the color developability is improved. Further, when a metal salt of a higher fatty acid is blended as a higher fatty acid derivative, the laser beam absorption efficiency is improved and a white marking with high whiteness can be obtained.

  Examples of the higher fatty acid include saturated or unsaturated higher fatty acids having about 12 to 30 carbon atoms such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linolenic acid. Derivatives of higher fatty acids include salts, esters, amides and the like. Examples of the salts of higher fatty acids include alkali metals of higher fatty acids such as zinc laurate, magnesium stearate, calcium stearate, barium stearate, zinc stearate, copper stearate, lead stearate, aluminum stearate, sodium oleate, etc. Salts, alkaline earth metal salts, transition metal salts, and the like. Examples of higher fatty acid amides include ethylene bisstearylamide and lauric acid amide. As the higher fatty acid or derivative thereof, stearic acid or a stearic acid derivative (salt, ester, amide, etc.) is particularly preferably used.

  The amount of the higher fatty acid or derivative thereof used is, for example, about 0.01 to 5 parts by weight, preferably about 0.02 to 3 parts by weight with respect to 100 parts by weight of the thermoplastic resin composition. If the amount used is less than 0.01 parts by weight, the effect of improving the dispersibility of the coloring material is small, and if it exceeds 5 parts by weight, problems such as evaporation and volatilization during molding and adhesion to the mold may occur.

  The thermoplastic resin composition for white marking of the present invention contains additives such as a compatibilizer, a flame retardant, a filler, a stabilizer, a lubricant, a dispersant, an additive, a foaming agent, and an antibacterial agent, as necessary. You may go out.

  The thermoplastic resin composition for white marking of the present invention can be prepared by mixing (for example, melt mixing) the above-described components by a conventional mixing method using an extruder, a kneader, a mixer, a roll, or the like. .

  Various molded bodies can be produced by subjecting the thermoplastic resin composition for white marking of the present invention to conventional molding methods such as extrusion molding, injection molding, and compression molding. Then, by irradiating these molded bodies with a laser beam, a white marking-formed molded body having a white marking on the surface is obtained. The type of laser used for marking is not particularly limited and may be any of a gas laser, a semiconductor laser, an excimer laser, a YAG laser, and the like, but a YAG laser is most preferably used. The type of marking is not particularly limited, and may be any of characters, symbols, designs, pictures, photographs, and the like.

  The white marking-formed molded body thus obtained can be used for, for example, OA equipment such as a computer keyboard, automobile parts (button parts, etc.), household goods, and building materials.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples.

Examples 1-20, Comparative Examples 1-5
After blending each component described in Tables 1-3 and producing pellets by extrusion, a plate with a thickness of 3 mm is produced from the pellets by injection molding. 10 mm square BOX (line distance of 75 μm) was drawn]. An Nd: YAG laser (wavelength: 1064 nm) was used as the laser. As the irradiation conditions, the aperture is fixed to 2 mm in diameter, the light source current value (LC), the frequency (QS), and the printing speed (SP) are changed within the following ranges, and marking is performed under the condition that the most clear white print is obtained. Carried out.
Light source current value (LC): 8-20A
Frequency (QS): 1-10kHz
Printing speed (SP): 100-1500 nm / second

Evaluation Test The following evaluation test was performed on each plate with the white marking obtained in Examples and Comparative Examples. The results are shown in Tables 1-3.

(1) Laser marking property For each plate, the hue (whiteness; L value) of the white marking was measured with a color difference meter [manufactured by Nippon Denshoku Kogyo Co., Ltd., trade name “Σ80”]. ) Was evaluated.

(2) Stain resistance (stain resistance) of the marking part
For each plate, the marking part with the highest whiteness was painted with white black magic black [manufactured by KOKUYO Co., Ltd.], and after 1 minute, the ink was wiped off with Kimwipe paper [manufactured by Jujo Kimberley Co., Ltd.]. The whiteness (L value) before magic application and after magic wiping is measured with a color difference meter [manufactured by Nippon Denshoku Kogyo Co., Ltd., trade name “Σ80”], and the whiteness L _1a before magic application and after magic wiping are removed. The difference (ΔL _a = L _1a −L _2a ) from the whiteness L _2a was determined and evaluated as an index of stain resistance of the marking portion.

(3) Abrasion resistance of the marking part The marking part with the highest whiteness on each plate is subjected to a wear test using a reciprocating frictional wear tester [trade name "AFT-15MS", manufactured by Orientec Co., Ltd.] The whiteness (L value) before and after the wear test was measured with a color difference meter [manufactured by Nippon Denka Kogyo Co., Ltd., trade name “Σ80”], and the whiteness L _1b before the wear test and the whiteness after the wear test A difference from L _2b (ΔL _b = L _1b −L _2b ) was determined and evaluated as an index of wear resistance. The conditions for the wear test are as follows.
Load: 400g
Number of sliding times: 10,000 times Moving speed: 50 mm / sec
Travel distance: 50mm
Sliding material: Eraser [Product name "MachineEraserStripes75216 (Softgreen, No75)", manufactured by Faber-Castell Corp.]

(4) Thousand turn-up test Cut a cross into the surface of each plate with a cutter, paste a transparent packing tape [trade name “375DS”, manufactured by Sumitomo 3M Co., Ltd.], and then a plastic eraser [trade name “ Rub with poppy 51 ", manufactured by KOKUYO Co., Ltd.] to ensure sufficient contact. After 3 minutes from the close contact, the tape was peeled off at a stroke, and the presence or absence of the resin piece adhering to the tape was visually confirmed, and the evaluation was 1000 sheets turned up.

[Ingredients used in Examples and Comparative Examples]
・ Resin ingredients
a-1-1: Copolymer (MI: 12 g / 10 min) composed of 18% by weight of styrene, 4% by weight of acrylonitrile, 58% by weight of methyl methacrylate and 20% by weight of butadiene, average particle diameter of rubber 300 nm
a-1-2: Copolymer (MI: 18 g / 10 min) composed of 22% by weight of styrene, 11% by weight of acrylonitrile, 58% by weight of methyl methacrylate and 9% by weight of butadiene, average particle diameter of rubber 250 nm
a-2-1: Copolymer comprising 80% by weight of styrene and 20% by weight of acrylonitrile (MI: 223 g / 10 min)
a-2-2: Copolymer comprising 76% by weight of styrene and 24% by weight of acrylonitrile (MI: 100 g / 10 min)
a-2-3: Copolymer comprising 76% by weight of styrene, 24% by weight of acrylonitrile and 3% by weight of methacrylic acid (MI: 201 g / 10 min)
a-3-1: Polymethyl methacrylate The resin is a commercially available product or one prepared by a known polymerization method. MI is a measured value at 230 ° C. and 5 kg.
・ Low viscosity olefin polymer (abbreviated as “low viscosity olefin” in the table)
Low-viscosity olefin polymer 1: polyethylene wax, manufactured by Honeywell, trade name “AC polyethylene 9A”, η 0.11 Pa · s
Low-viscosity olefin polymer 2: polyethylene wax, manufactured by Honeywell, trade name “AC polyethylene 715”, η 0.66 Pa · s
Low-viscosity olefin polymer 3: polyethylene wax, manufactured by Mitsui Chemicals, Inc., trade name “Mitsui High Wax 800P”, η 2.04 Pa · s
Low-viscosity olefin polymer 4: Polypropylene wax, manufactured by Mitsui Chemicals, trade name “Mitsui High Wax NP805”, η 0.90 Pa · s
Low-viscosity olefin polymer 5: Polyethylene wax, manufactured by Mitsui Chemicals, Inc., trade name “Mitsui High Wax 100P”, less than η measurement limit (0.01 Pa · s) • Olefin polymer (in the table, “olefin polymer” (Abbreviation)
Olefin polymer 1: homopolypropylene, manufactured by Sun Allomer Co., Ltd., trade name “Sun Allomer PM900A”, η 784 Pa · s
Olefin polymer 2: high density polyethylene, manufactured by Mitsui Chemicals, Inc., trade name “Hi-Zex 1300J”, η 883 Pa · s
The viscosity (η) of the low-viscosity olefin polymer and the olefin polymer was measured by preparing a 1 mm thick test piece with a hot press and rotating a rheometer [trade name “PHYSICA UDS200”, Nippon Sebel Hegner Co., Ltd. Manufactured] under the conditions of a measurement temperature of 230 ° C. and a shear rate of 1 sec ⁻¹ ).
・ Stearate: Commercially available product or one prepared by a known synthesis method ・ Antioxidant: Phenol antioxidant, trade name “Irganox 1010”, manufactured by Ciba Specialty Chemicals Co., Ltd. ・ Coloring material Carbon black : Use a commercial product with an average particle size of 17 nm Titanium oxide: Use a commercial product

Claims (15)

(Meth) acrylic acid C _1-18 alkyl ester, acrylonitrile, styrene and rubber component (a-1) 60-100 parts by weight copolymer, acrylonitrile and styrene copolymer (a-2) 0 40 parts by weight [however, (a-1) + (a-2) = 100 parts by weight] a rubber-reinforced styrene-based resin and a resin (A) 100 containing at least one selected from polymethyl methacrylate 0.1 to 5 parts by weight of a low-viscosity olefin polymer (B1) having a viscosity (η) of 0.01 to 100 Pa · s in a rotary rheometer (230 ° C., shear rate 1 sec ⁻¹ ) and / Or 0.15 parts by weight of an olefin polymer (B2) having a viscosity (η) exceeding 100 Pa · s and 0.0001 to 5 parts by weight of a colorant (C), and white by irradiation with a laser beam. Ma Ring is white-marking thermoplastic resin composition capable. The monomer composition of the copolymer (a-1) is (meth) acrylic acid C _1-18 alkyl ester 40 to 60% by weight, acrylonitrile 3 to 14% by weight, styrene 12 to 25% by weight, rubber component 6 to claim 1 white-marking thermoplastic resin composition according is 24 wt%. Monomer composition of the copolymer (a-2) is acrylonitrile 10-26% by weight of styrene 74-90% by weight and is claim 1 white-marking thermoplastic resin composition. Copolymer (a-1) according to claim 1 white-marking thermoplastic resin composition according average particle size of the rubber component is 150~800nm of. The ratio (former / latter) of the melt index (MI; 230 ° C., 5 kg) of the copolymer (a-1) to the melt index (MI; 230 ° C., 5 kg) of the copolymer (a-2) is 1/200. claim 1 white-marking thermoplastic resin composition according in the range of ~ 1/2.   The thermoplastic resin composition for white marking according to claim 1, wherein the low-viscosity olefin polymer (B1) is at least one selected from polyethylene wax and polypropylene wax.   The thermoplastic resin composition for white marking according to claim 1, wherein the olefin polymer (B2) is at least one selected from polyethylene and polypropylene. Colorant (C) is a white-marking thermoplastic resin composition of claim 1 comprising a dark colored Pigments.   The thermoplastic resin composition for white marking according to claim 1, wherein the color material (C) is carbon black having an average particle diameter of 10 to 90 nm. The white marking thermoplastic resin according to claim 1, further comprising 0.01 to 5 parts by weight of a saturated or unsaturated fatty acid having 12 to 30 carbon atoms or a derivative thereof per 100 parts by weight of the thermoplastic resin composition. Composition. The thermoplastic resin composition for white marking according to claim 10 , wherein the saturated or unsaturated fatty acid having 12 to 30 carbon atoms or a derivative thereof is a metal salt of a saturated or unsaturated fatty acid having 12 to 30 carbon atoms . White markable moldings made of a white-marking thermoplastic resin composition according to any one of claims 1 to 11. The white marking method which irradiates a laser beam to the molded object of Claim 12, and performs white marking. The white mark formation molded object by which the white marking was given to the molded object of Claim 12 by irradiation of the laser beam. The molded body to be subjected to white marking is composed of 60 to 100 parts by weight of a copolymer (a-1) composed of (meth) acrylic acid C _1-18 alkyl ester, acrylonitrile, styrene and a rubber component, and a copolymer composed of acrylonitrile and styrene. Copolymer (a-2) 0 to 40 parts by weight [provided that (a-1) + (a-2) = 100 parts by weight] at least one selected from rubber-reinforced styrene resin and polymethyl methacrylate containing resin (a) 100 parts by weight, rotary rheometer (230 ° C., a shear rate of 1 sec ^-1) a low viscosity olefin polymer viscosity at (eta) is a 0.01~100Pa · s (B1) 0.1 to 5 parts by weight and / or 0.1 to 1 part by weight of an olefin polymer (B2) having a viscosity (η) exceeding 100 Pa · s and 0.0001 to 5 parts by weight of a colorant (C) are blended. Heat By constituting in sexual resin composition, a method of preventing the fouling and / or wear of the marking portion of the white marks formed molded article obtained by subjecting the white markings molded body subjected to the white markings.