JP4873409B2 - Thermoplastic resin composition for laser marking - Google Patents

Description

  The present invention relates to a thermoplastic resin composition for laser marking capable of forming a marking by irradiation with a laser beam, and a laser-markable product comprising a thermoplastic resin composition for laser marking (a molded body, a sheet, a film, one of the components constituting them). The present invention relates to a laser marking method in which laser marking is performed by irradiating a laser beam to a product that can be laser-marked, and a product on which marking obtained by this laser marking method has been applied.

  Printing using laser light irradiation (referred to as “laser marking”) has become widespread as an alternative to printing and painting with ink. In this method, the irradiated laser beam is absorbed by the energy absorbing material in the resin to generate heat, and the resin is visualized by carbonization, foaming or evaporation of the resin. Therefore, selection of a substance that absorbs laser energy is important. In the case of general laser marking, carbon black or graphite is often selected as a laser energy absorbing material because it is inexpensive (Patent Document 1 and the like). However, these substances have a large coloring power, and even if added in a small amount, the color is greatly affected. Therefore, depending on the target background color, the amount of addition is limited. In particular, when the target value is a high saturation color such as a primary color, a high brightness color, or a color with a low color pigment concentration, it is impossible to add an amount necessary for color development.

  On the other hand, materials other than carbon black have been proposed as energy absorbing materials (Patent Documents 2, 3, 4, etc.). For example, the use of a pearlescent pigment coated on mica has been proposed, but there is a problem that the background color that can be used is limited because the pearly luster remains. In addition, although the use of manganese violet, cobalt violet compounds, etc. has been proposed, there are problems that the background color that can be used is limited and the safety of these compounds remains unclear. Moreover, in the resin composition for marking containing a metal and a metal oxide, there exists a problem that a residue remains when it incinerates after it becomes unnecessary.

JP 2000-44736 A Japanese Patent Laid-Open No. 7-286074 JP-A-9-12776 JP-A-2-204888

  An object of the present invention is to provide a thermoplastic resin composition for laser marking that is excellent in laser marking properties when irradiated with a laser, a degree of color change with respect to a base material, visibility, color uniformity, and the like. In particular, it is an object of the present invention to provide a thermoplastic resin composition for laser marking capable of clear printing without blending carbon black, metal, or metal oxide.

  Another object of the present invention is to provide a molded article, a sheet, a film, or a product comprising the thermoplastic resin composition for laser marking having the above-described excellent characteristics as a part of the structure, a laser to the molded article, etc. It is an object of the present invention to provide a marking method in which laser marking is performed by irradiating the marking, and a product provided with the marking obtained by this method.

  As a result of intensive studies to achieve the above object, the present inventor can obtain a clear print without adding carbon black, metal oxide, or the like when an organic fiber is added to the thermoplastic resin composition. As a result, the present invention was completed.

That is, this invention provides the thermoplastic resin composition for laser marking containing the thermoplastic resin which is a polyolefin-type polymer, and the at least 1 sort (s) of organic fiber selected from a cellulose fiber, a nylon fiber, and a polyester fiber .

As said organic fiber, the fiber whose average fiber diameter is 0.1-1000 micrometers and whose average aspect-ratio is 2-1000 can be used. The melting point of the thermoplastic resin is 230 ° C. or lower . The content of the organic fiber is, for example, 0.1 to 80% by weight.

  The present invention also provides a molded article, a sheet, a film, or a product comprising the thermoplastic resin composition for laser marking as a part of the structure.

  The present invention further provides a marking method in which laser marking is performed by irradiating a laser on the molded body, sheet, film, or a product containing the same as a part of the structure.

  For example, an infrared laser can be used as the laser.

The present invention further provides a product provided with the marking obtained by the above marking method. In addition to the above invention, the present specification includes a thermoplastic resin composition for laser marking comprising a thermoplastic resin and an organic fiber. The organic fiber is a cellulose fiber, a regenerated cellulose fiber, an animal fiber, a semi-synthetic fiber, and a synthetic fiber. The thermoplastic resin composition for laser marking which is at least one selected from the above, and the thermoplastic resin composition for laser marking wherein the thermoplastic resin is a polyolefin polymer, a polystyrene polymer or an acrylic polymer Describe.

  The thermoplastic resin composition for laser marking of the present invention is excellent in laser marking property when irradiated with laser, degree of color change with respect to the base material, visibility, color uniformity, etc., and contains carbon black, metal, and metal oxide Clear printing is possible even without this.

  The thermoplastic resin in the thermoplastic resin composition for laser marking of the present invention is not particularly limited, and examples thereof include polyolefin polymers (polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, etc .; Any of homopolymer, random copolymer, block copolymer, etc.), polyamide (polyamide 6, polyamide 66, polyamide 46, polyamide 12, etc.), polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), polyphenylene oxide, polyphenylene sulfide , Polyacetal (polyoxymethylene, etc.), polyether ester amide, polyether imide, polyimide, polyether ester ketone, polyarylate, chlorine-based polymer, fluorine-based Polymers, polyurethanes, thermoplastic elastomers, cellulosic polymers, polycarbonates, styrene polymers containing styrene monomers as constituent monomers, acrylic polymers containing acrylic monomers as constituent monomers, etc. Can be mentioned. These thermoplastic resins can be used alone or in combination of two or more.

  Examples of the styrene monomer that is a constituent monomer of the styrenic polymer include styrene and alkyl-substituted styrene (for example, vinyl toluene such as o-methyl styrene, m-methyl styrene, and p-methyl styrene). , Halogen-substituted styrene (eg, o-chlorostyrene, p-chlorostyrene, o-bromostyrene, etc.), α-alkyl substituted styrene substituted with an alkyl group at the α-position (eg, α-methylstyrene, α-ethylstyrene, etc.) ) And the like. Among these, styrene, vinyl toluene, α-methyl styrene and the like are particularly preferable.

  The styrenic polymer may contain a structural unit of a monomer other than the styrenic monomer. Such a monomer may be a monomer copolymerizable with a styrene monomer, and examples thereof include a vinyl cyanide monomer, maleic anhydride, and an imide monomer. The styrene polymer may contain a rubber component as a constituent component.

  Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile. Examples of the imide monomer include N-alkylmaleimide (eg, N-methylmaleimide, N-ethylmaleimide, etc.), N-cycloalkylmaleimide (eg, N-cyclohexylmaleimide, etc.), N-arylmaleimide [ For example, N-phenylmaleimide, N- (2-methylphenyl) maleimide, etc.] are included. 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. Is mentioned. The rubber component can be contained in the styrenic polymer by a blend method, copolymerization (graft copolymerization, block copolymerization) or the like. In the present specification, a rubber component contained in a polymer by a blending method is also referred to as a “copolymer” for convenience.

  Representative examples of styrene polymers include polystyrene, styrene-acrylonitrile copolymer (AS resin), styrene-butadiene copolymer, styrene-acrylonitrile-butadiene copolymer (ABS resin), α-methylstyrene modified ABS. Resin, imide-modified ABS resin, styrene-maleic anhydride copolymer (SMA), acrylonitrile-ethylene-propylene-styrene copolymer (AES), high impact polystyrene (HIPS; blend of polystyrene and synthetic rubber, or synthesis) Examples thereof include polymers obtained by graft-polymerizing styrene to rubber.

Examples of the acrylic monomer that is a constituent monomer of the acrylic polymer include (meth) acrylic acid and (meth) acrylic acid ester. 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 (meth) acrylic acid cyclohexyl; (meth) acrylic acid aryl ester such as phenyl (meth) acrylate ; (Meth) acrylates such as benzyl (meth) acrylate Examples include aralkyl oxalate. Among these, (meth) acrylic acid C _1-10 alkyl ester [particularly (meth) acrylic acid C _1-4 alkyl ester] such as methyl methacrylate and butyl acrylate is preferable. Acrylic monomers may be used alone or in combination of two or more.

  The acrylic polymer may contain a structural unit of a monomer other than the acrylic monomer. Such a monomer is not particularly limited as long as it is a monomer copolymerizable with an acrylic monomer. For example, vinyl cyanide monomer, styrene monomer, maleic anhydride, imide System monomers and the like. 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, styrene monomer, and imide monomer include those described above.

  The acrylic polymer 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. As the rubber component, those described above can be used. The rubber component can be contained in the acrylic polymer by a blend method, copolymerization (graft copolymerization, block copolymerization) or the like.

  The acrylic polymer 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.

Preferred acrylic polymers include (i) (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 (especially methyl methacrylate) and carbon monoxide, (iii) polymethyl methacrylate, (iv) methacrylic acid-styrene copolymer, etc. It is.

  The acrylic polymer can be used in combination with other polymers. Examples of such other polymers include polystyrene, styrene-acrylonitrile copolymer (AS resin), styrene-butadiene copolymer, styrene-acrylonitrile-butadiene copolymer (ABS resin), and α-methylstyrene-modified ABS. Examples thereof include resins, imide-modified ABS resins, styrene-maleic anhydride copolymers (SMA), butadiene-acrylonitrile copolymers, acrylonitrile-ethylene-propylene-styrene copolymers (AES), and the like. Among these, a styrene-acrylonitrile copolymer is particularly preferable. By including a styrene-acrylonitrile copolymer (AS resin) in the resin, heat resistance, light resistance, oil resistance, mechanical strength, molding processability, and the like are improved.

The melting point of the thermoplastic resin is not particularly limited, but (1) a crystalline resin having a melting point of 230 ° C. or lower (for example, 120 to 210 ° C., preferably 130 to 200 ° C.), and (2) a temperature of 200 ° C. and a shear rate of 100 sec ^{− 1.} Melt viscosity measured with a capillary rheometer is 10 to 10 ⁴ Pa · s (10 ² to 10 ⁵ poise) (preferably 50 to ⁵ × 10 ³ Pa · s, more preferably 10 ^{2 to} 3 × 10 ³ Pa. -At least 1 type of resin selected from the amorphous resin of s) is used preferably.

  Among the above thermoplastic resins, polyolefin polymers such as polypropylene, polystyrene polymers, acrylic polymers (including blends of acrylic polymers and other polymers) and the like are preferable, Polyolefin polymers are preferred from the viewpoints that the processing temperature can be lowered and organic fibers having low heat resistance can be used, and that the appearance is good even when a large amount of organic fibers are blended.

  The thermoplastic resin composition for laser marking of the present invention contains an organic fiber. Organic fibers include cellulose fibers, regenerated cellulose fibers, animal fibers, semi-synthetic fibers, and synthetic fibers. Examples of the cellulose fiber include dissolving pulp, hemp fiber, cotton fiber (including cotton flock and cotton polyester), bamboo fiber, bagasse, and Chinese reed. Examples of the regenerated cellulose fiber include rayon and copper ammonia rayon. Examples of animal fibers include wool, cashmere, mohair, silk, and the like. Examples of semi-synthetic fibers include acetate fibers. Examples of synthetic fibers include nylon fibers, aramid fibers, polyester fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, polyacrylonitrile fibers, polyethylene fibers, polypropylene fibers, polyurethane fibers, polyfluoroethylene fibers, acrylic fibers. , Polyimide fiber, polylactic acid fiber and the like. Among these, cellulose fibers (particularly, dissolved pulp, cotton fibers, etc.), nylon fibers, aramid fibers, polyester fibers, and the like are preferable in terms of a large degree of discoloration with respect to the base material during marking. Cellulose fibers are also preferable from the viewpoint of utilization of non-petroleum resources. Among cellulose fibers, cellulose (for example, dissolved pulp, cotton fiber, etc.) having an α-cellulose content of 80% by weight or more is preferable because it has a clean substrate and is excellent in the visibility of marked characters and the like. Moreover, since aramid fiber is excellent in heat resistance, a thermoplastic resin having a high melting point can be used as a base material. An organic fiber can be used individually or in combination of 2 or more types.

  Although the size of the organic fiber in the thermoplastic resin composition for laser marking is not particularly limited, the average fiber diameter is preferably 0.1 to 1000 μm, more preferably 1 to 500 μm, still more preferably 5 to 200 μm, and particularly preferably. Is about 10 to 50 μm. The average fiber length is preferably 0.01 to 100 mm, more preferably 0.01 to 50 mm, still more preferably 0.1 to 10 mm, and particularly preferably about 0.1 to 5 mm. The average aspect ratio of the organic fiber is preferably 2 to 1000, more preferably 3 to 500, still more preferably 5 to 500, and particularly preferably about 10 to 500 from the viewpoint of strength and the like.

  The content of the organic fiber in the thermoplastic resin composition for laser marking is, for example, about 0.1 to 80% by weight, preferably about 1 to 70% by weight, and more preferably about 5 to 65% by weight. If the organic fiber content is too low, the conversion efficiency of the laser beam to heat will be reduced and the marking will tend to be thin. Conversely, if the content is too high, the surface of the molded product will become a spotted pattern, or the marked characters will be visible. It becomes easy to fall.

  The thermoplastic resin composition for laser marking of the present invention may contain carbon black as necessary. By blending carbon black, the conversion efficiency of laser light into heat can be further increased. Carbon black is not particularly limited, and may be any of acetylene black, lamp black, thermal black, furnace black, channel black, ketjen black, and the like. The average particle diameter of carbon black is, for example, about 10 to 90 nm, preferably 14 to 90 nm, and more preferably about 17 to 50 nm. If the particle size of the carbon black is too small, a large amount of energy is required for marking, and conversely if too large, physical properties such as mechanical strength are likely to deteriorate.

  When carbon black is blended, the amount used is, for example, 0.00001-5 parts by weight, preferably 0.0001-1 part by weight, more preferably 0.0002-0.100 parts by weight with respect to 100 parts by weight of the thermoplastic resin. About 1 part by weight. When the target color is a chromatic and light color, the amount used is preferably about 0.00001 to 0.1 parts by weight, more preferably 0.0001 to 0. 0, with respect to 100 parts by weight of the thermoplastic resin. About 05 parts by weight, more preferably about 0.0005 to 0.004 parts by weight. On the other hand, when the base color is not easily affected by carbon black, such as a color having a high pigment concentration, the amount of carbon black used can be increased, for example, 0.0001 to 100 parts by weight of the thermoplastic resin. About 3 parts by weight is preferable, more preferably about 0.0002 to 0.5 parts by weight, and still more preferably about 0.0005 to 0.3 parts by weight. When the amount of carbon black used is large, the base color tends to be dull and the marking color may be excessive and the design may become dark.

  The thermoplastic resin composition for laser marking of the present invention may contain other color materials (color materials other than carbon black) in order to color the resin. Such a colorant can be appropriately selected from inorganic or organic dyes and pigments. For example, 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 pigments (eg, chrome green), dark dyes other than carbon black (eg, graphite, titanium black, black iron oxide, etc.). These color materials can be used alone or in combination of two or more.

  A white pigment such as titanium oxide scatters a laser beam and enhances the absorption efficiency of the laser beam and the conversion efficiency into heat, so that a white marking with a very high whiteness can be obtained. Moreover, the irradiation energy of a laser beam can be reduced by containing a white dye / pigment.

  The amount of the coloring material used can be appropriately selected from the amount necessary for obtaining a desired color. Usually, for example, 5 parts by weight or less (for example, 0.0001 to 5 weights) with respect to 100 parts by weight of the thermoplastic resin. Part), preferably 2 parts by weight or less (for example, 0.001 to 2 parts by weight). If the amount of these coloring materials used is too large, the marking color becomes tinged with the hue of the dye / pigment, which is not preferable.

  The thermoplastic resin composition for laser marking of the present invention can be used as a compatibilizer, flame retardant, filler, antioxidant, stabilizer, lubricant, dispersant, additive, foaming agent, antibacterial agent, etc. An additive may be included.

  The thermoplastic resin composition for laser 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. .

  By subjecting the thermoplastic resin composition for laser marking of the present invention to a conventional molding method such as extrusion molding, injection molding, compression molding, or coating an article or the like, a molded body (three-dimensional structure) ), Sheets, films, and products containing these as part of the structure. As a preferable molded body, a molded body made of a transparent resin, a sheet, a film, a skeleton, and the like that are dull in color and easily deteriorate in appearance when blended with carbon black alone are used.

  And if these molded bodies, sheets, films, and products that include these as a part of the structure are irradiated with laser light, the irradiation energy is amplified by reflection at the interface between the resin and organic fibers, or the resin is carbonized efficiently. And / or foaming (or transpiration) to obtain a molded product having a laser marking on the surface with a difference in contrast and hue between the laser irradiation portion and the substrate of the molded product adjacent thereto. The color of the marking varies depending on the type of thermoplastic resin constituting the molded body, the organic fiber to be added, the type of color material, and the like.

  The type of laser used for marking is not particularly limited, and may be any of a far infrared laser such as a carbon dioxide laser, a near infrared laser such as a YAG laser, a semiconductor laser, and an excimer laser, but an infrared laser is preferably used. Is done. The type of marking is not particularly limited, and may be any of characters, symbols, designs, pictures, photographs, and the like.

  The mark-formed product thus obtained can be used, for example, for daily goods, automobile parts (button parts, etc.), home appliances, toilet seats, design parts, OA equipment such as computer keyboards, household goods, building materials, and the like.

  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 to 21, Comparative Examples 1 to 6 (Examples 10 to 13 are reference examples)
After blending each component described in Tables 1 to 4 (numerical values in the table are parts by weight) and producing pellets by extrusion, a plate having a thickness of 3 mm is produced from the pellets by injection molding. It was attached to the evaluation test.

Evaluation test The following evaluation test was conducted. The results are shown in Tables 1-4.

(1) Marking availability Using the laser marker (trade name “Marker Engine SL475H” manufactured by NEC Corporation) on the surface of the plate (thickness 3 mm) obtained above, laser output 2.5 W, pitch 50 μm, bite 120 μm Then, marking with a size of 10 mm × 10 mm was performed under a scanning speed of 400 mm / sec, and the possibility of marking was evaluated by visual observation. The evaluation criteria are as follows.
○: Marked clearly △: Marking can be confirmed visually ×: Marking cannot be confirmed

(2) Discoloration degree Using a laser marker (trade name “Marker Engine SL475H” manufactured by NEC Corporation) on the surface of the plate (thickness 3 mm) obtained above, laser output 2.5 W, pitch 50 μm, bite 120 μm Marking with a size of 10 mm × 10 mm was performed under a scanning speed of 400 mm / sec. ΔE was measured with a color difference meter (trade name “CM3600d” manufactured by Konica Minolta Co., Ltd.), and the degree of discoloration of the marking portion relative to the plate base material was evaluated according to the following criteria.
○: ΔE is 10 or more Δ: ΔE is 5 or more and less than 10 ×: ΔE is less than 5

(3) Visibility On the surface of the plate (thickness 3 mm) obtained above, using a laser marker (trade name “Marker Engine SL475H” manufactured by NEC Corporation), laser output 2.5 W, frequency 3.0 kHz, Printing was performed under conditions of a printing height of 1.0 mm and a scanning speed of 100 mm / sec, and the visibility of printed characters was evaluated by visual observation. The evaluation criteria are as follows.
○: All marked characters can be identified. △: Some marked characters can be identified. ×: Most marked characters cannot be identified.

(4) Color unevenness Using a laser marker (trade name “Marker Engine SL475H” manufactured by NEC Corporation) on the surface of the plate (thickness 3 mm) obtained above, laser output 2.5 W, pitch 50 μm, bite 120 μm Marking with a size of 10 mm × 10 mm was performed under a scanning speed of 400 mm / sec, and the color uniformity of the marking portion was evaluated by visual observation. The evaluation criteria are as follows.
○: Marked evenly △: Spots are partially present ×: Marked with speckled pattern

[Ingredients used in Examples, etc.]
-Resin component Polypropylene: Trade name "Sun Allomer PMB60A", manufactured by Sun Allomer, Acid-modified polypropylene: Trade name "Yumex 1010", Sanyo Chemical Industries, Ltd. ABS: Trade name "AT05", Nippon A & L Corporation AS: Trade name "030SF" , Manufactured by Daicel Polymer Co., Ltd. HIPS: trade name “H53C”, manufactured by Toyo Styrene Co., Ltd. ・ organic fiber dissolving pulp: trade name “NDP-T”, manufactured by Nippon Paper Industries Co., Ltd. hemp fiber: trade name “310 Sial”, manufactured by International Fiber Corporation : Brand name "W260", Cotton Fiber made by International Fiber Corporation: Brand name "50CWCP", bamboo fiber made by International Fiber Corporation: Trade name "Bamboo Pulp", Phoenix Pulp & Paper Public Company Limited Bamboo fiber (ECF): Trade name " NWBP ", Phoenix Pulp & Paper Public Comp any Limited Bagasse: Trade name “Bagasse Pulp”, Environment Pulp and Paper Company Limited China Reed: Trade Name “Ashi Pulp”, Gold River Polyester Fiber: Trade Name “125WPF”, International Fiber Corporation Nylon Fiber: Trade Name “ 125WNF ", aramid fiber made by International Fiber Corporation: Trade name" SA-300 ", Testron fiber (a kind of polyester fiber) made by Soshin Lining: trade name" Tetron cut fiber C324 ", made by Toray Industries, Inc. Other glass fiber: Product Name “ECS-03-T-480”, manufactured by Nippon Electric Glass Co., Ltd. Talc: Product name “PS talc”, manufactured by Takehara Chemical Industries, Ltd.

◎

◎

◎

◎

Claims (8)

A thermoplastic resin composition for laser marking , comprising a thermoplastic resin that is a polyolefin-based polymer and at least one organic fiber selected from cellulose fibers, nylon fibers, and polyester fibers . The thermoplastic resin composition for laser marking according to claim 1 , wherein the organic fibers have an average fiber diameter of 0.1 to 1000 µm and an average aspect ratio of 2 to 1000 . The thermoplastic resin composition for laser marking according to claim 1 or 2, wherein the thermoplastic resin has a melting point of 230 ° C or lower .   The thermoplastic resin composition for laser marking according to any one of claims 1 to 3, wherein the organic fiber content is 0.1 to 80% by weight.   The molded object which consists of the thermoplastic resin composition for laser markings in any one of Claims 1-4, a sheet | seat, a film, or a product which contains them in a part of structure.   A marking method for performing laser marking by irradiating a laser on the molded article, sheet, film, or product containing them as a part of the constitution thereof.   The marking method according to claim 6, wherein the laser is an infrared laser.   A product provided with a marking obtained by the marking method according to claim 6 or 7.