JP7283149B2 - Film for laser marking - Google Patents

Description

The present invention relates to a film for laser marking.

Conventionally, textual information such as the place of manufacture, date of manufacture, and symbols is sometimes written on the surface of packaging materials for foods, medicines, etc. before or after the contents are contained and sealed. In order to describe this character information, it is printed by a thermal printer or an inkjet printer, or a separately printed label is attached. However, in the case of packages with irregular surfaces or soft packages containing contents that are vulnerable to impact, mechanical printing methods using a thermal head, such as a thermal printer, are not suitable. However, there are problems such as disappearance or detachment of the print due to adhesion of oily contents to the printed part or rubbing during handling or transportation. Furthermore, attaching a separately printed label increases the label attaching cost.

As a printing method that does not have these problems, a printing method using laser marking is used, in which characters and symbols are drawn and written by irradiating the printed surface of the package with a laser beam. A film as a packaging material for laser marking used for printing by laser marking includes a substrate layer, a laser coloring layer, and a sealant layer (Patent Document 1). The laser coloring layer, on which a printed image is formed by laser light irradiation, is not exposed on the outermost surface, but is covered with a substrate layer as a surface protective layer made of various films. The printing was performed by irradiating a laser beam.

Patent No. 6126420

However, the film used for the above-mentioned laser printing used as a packaging material or the like must have a total of three layers: a substrate layer, a laser coloring layer, and a sealant layer, so the film cannot be thick. In addition, the manufacturing cost was increased. If the film consists of a total of two layers, a laser coloring layer and a sealant layer, the laser coloring layer is the outermost layer. There were problems such as detachment.

SUMMARY OF THE INVENTION It is an object of the present invention to advantageously solve the above-mentioned problems, and to provide a film for laser printing, which can be made thinner and whose manufacturing cost can be suppressed.

As a result of extensive research on the film for laser printing, the inventors found that laser printing is possible even with a single layer by making a film containing a laser coloring agent in a resin that functions as a sealant. It was discovered that it is possible to seal.

The film for laser printing of the present invention based on the above findings contains a polyolefin resin and a laser color former, wherein the laser color former is a polymer substance, mica or mica-like substance, metal sulfide and one or more organic non-black It contains pigments.
Further, the film for laser printing of the present invention comprises a laser coloring layer containing a polyolefin resin and a laser coloring agent, wherein the laser coloring agent is a polymer substance, mica or mica-like substance, metal sulfide and one or more kinds of organic It contains a non-black pigment.

The laser-printing film of the present invention can be provided with a layer made of a polyolefin resin overlaid on the laser coloring layer. In addition, the laser coloring agent is added in an amount of 0.05 to 1.9% by mass of the mica or mica-like substance, and 0.05 to 2.9% by mass of the metal sulfide, and the above one type. It is preferable to contain 0.01 to 9.9% by mass of the above organic non-black pigment. The polyolefin-based resin is preferably one or more selected from low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, random polypropylene, homopolypropylene, and block polypropylene. .

According to the laser printing film of the present invention, the thickness can be reduced, and the manufacturing cost can be suppressed.

1 is a schematic cross-sectional view of one embodiment of the film for laser printing of the present invention. FIG. FIG. 3 is a schematic cross-sectional view of another embodiment of the film for laser marking of the present invention;

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the film for laser printing of this invention is described concretely, using drawing.
FIG. 1 shows a schematic cross-sectional view of one embodiment of the film for laser printing of the present invention. In FIG. 1, the laser-printing film 1 is a single-layer film, and the laser-printing film 1 contains a polyolefin resin and a laser coloring agent.

The polyolefin-based resin, which will be described later, is polyethylene, for example, and is a resin used as a sealant for packaging materials. Therefore, since the film for laser printing 1 contains a polyolefin resin, even a single layer has an effect as a sealant. Therefore, the laser-printing film 1 can be used as a packaging material by stacking a plurality of sheets and heat-sealing them.

In addition, the laser printing film 1 contains a laser coloring agent. By including the laser coloring agent in the laser-printing film 1 instead of forming it on the surface of the laser-printing film 1 by printing or the like, even if the laser-printing film 1 is rubbed in the process of handling or transportation as a packaging material, the printing can be performed. Problems such as disappearance or detachment do not occur. Since the polyolefin resin can transmit laser light, even if the laser printing film 1 contains a laser coloring agent, it can be colored by the laser coloring agent.

Therefore, the laser-printing film 1 does not necessarily require a separate protective layer or substrate layer for protecting the laser coloring layer. Also, it is not always necessary to provide a separate sealant layer. Therefore, since a protective layer, a base material layer, and a sealant layer are not required, the thickness of the packaging material can be reduced and the manufacturing cost can be suppressed.

FIG. 2 shows a schematic cross-sectional view of another embodiment of the film for laser printing of the present invention. In FIG. 2, the laser printing film 10 is a multi-layer film, and in the example shown in FIG. A polyolefin resin layer 12 and a second polyolefin resin layer 13 formed on the other surface of the laser coloring layer 11 . Like the laser-printing film 10 shown in FIG. 2, the laser-printing film of the present invention is not limited to a single-layer film, but may be a multi-layer (multi-layer) film.

The laser coloring layer 11 of the laser printing film 10 contains a polyolefin resin and a laser coloring agent. The polyolefin resin of the laser coloring layer 11 is, for example, polyethylene, like the laser printing film 1 shown in FIG. 1, and is a resin used as a sealant for packaging materials. Therefore, since the laser coloring layer 11 contains the polyolefin resin, it adheres closely to the first polyolefin resin layer 12 and to the second polyolefin resin layer 13, and the three-layer structure as a whole has a laser structure. A printing film 10 can be used. Although it depends on the manufacturing method, the thickness of the laser-printable film 10 can be reduced by co-extrusion, for example, in the same manner as the laser-printable film 1 shown in FIG.

The multi-layer laser printing film is not limited to the three-layer structure shown in FIG. , or a structure having four or more layers including the laser coloring layer 11 .

In addition, the laser coloring layer 11 of the film for laser printing 10 contains a laser coloring agent. By including a laser coloring agent in the laser coloring layer 11 of the multi-layered laser printing film 10, for example, even if the laser coloring layer 11 is the outermost layer, it may be rubbed during the process of handling or transportation as a packaging material. Also, problems such as disappearance or detachment of printed characters do not occur. The polyolefin resin of the first polyolefin resin layer 12, the second polyolefin resin layer 13, and the laser coloring layer 11 can transmit laser light. Therefore, even if the laser coloring layer 11 located between the first polyolefin resin layer 12 and the second polyolefin resin layer 13 in the laser printing film 10 contains a laser coloring agent, the laser coloring agent can be colored.

Although it depends on the coloring mechanism of the laser coloring agent in the laser coloring layer 11, the laser coloring layer 11 does not contain the laser coloring agent in the first polyolefin resin layer 12 or the second polyolefin resin layer 13. An embodiment containing an agent is preferred. According to this aspect, compared with the case where each layer contains a laser coloring agent, the coloring property is good, and in particular, in the case of the suitable laser coloring agent described later, clear printing can be achieved.

Further, since the laser coloring layer 11 contains a polyolefin resin, it can be used as a sealant if necessary. In addition, when the laser-printing film 10 is used as a packaging material by providing the first polyolefin-based resin layer 12 and the second polyolefin-based resin layer 13 in addition to the laser-coloring layer 11, In addition, it is possible to improve the sealing performance when a plurality of sheets are stacked and heat-sealed.

As described above, the thickness of the laser-printing film 10 can be reduced when used as a packaging material, and the manufacturing cost can be suppressed.

Hereinafter, each layer of the film for laser printing 1 and the film for laser printing 10 will be specifically described.

[Laser printing film 1 and laser coloring layer 11]
The laser printing film 1 and the laser coloring layer 11 are layers that develop colors upon receiving a laser, and contain a polyolefin resin and a laser coloring agent.

The polyolefin resin can be one or more selected from low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, random polypropylene, homopolypropylene and block polypropylene. Since all of these resins have sealability, even a single layer such as the laser-printing film 1 can be heat-sealed as a packaging material. Among these resins, low-density polyethylene and linear low-density polyethylene are preferable when providing low-temperature sealability, and random polypropylene, homopolypropylene, block polypropylene, and high-density polyethylene are preferable for applications requiring heat resistance. is preferred.

It is preferred that the laser color former comprises polymeric substances, mica or mica-like substances, metal sulfides and one or more organic non-black pigments. Laser color formers containing such components are described, for example, in Japanese Patent No. 4,695,085. A laser color former comprising polymeric substances, mica or mica-like substances, metal sulfides, and one or more organic non-black pigments agglomerates in a layer to exhibit a dark color when exposed to a laser, thereby producing color. A laser printing film 1 or a film of the laser coloring layer 11 can be manufactured by kneading the laser coloring agent containing the above components with the polyolefin resin described above as a masterbatch to form a film.

The laser coloring agent containing the above components does not contain the organic solvent contained in the ink used for printing, since it is not used to form the laser printing film 1 or the laser coloring layer 11 by printing. Therefore, the laser printable film 1 or the laser printable film 10 does not contain residual solvent. Therefore, there is an effect that it is suitable for use as a BIB (bag in box) packaging material for applications where organic solvents are not desired, such as beverages, foods, alcoholic beverages, industrial chemicals, and the like.

In addition, some laser coloring layers formed by conventional printing are formed by printing ink containing titanium oxide as a laser coloring agent. Marking was done by carbonizing or discoloring the surrounding constituent substances. The laser coloring layer printed with such a conventional ink containing titanium oxide exhibits an overall white color due to the color of the titanium oxide contained in the layer. was predominantly white. On the other hand, the above-described laser color former containing the polymer substance, mica or mica-like substance, metal sulfide, and one or more organic non-black pigments does not contain titanium oxide, so it is light transmissive before laser printing. There is an effect that it is possible to make a film having a high and almost transparent property.

The laser coloring agent containing the above components is preferably contained in a single layer (laser printing film 1 or laser coloring layer 11) in an amount of 3 to 99% by mass as a masterbatch. If the amount is less than 3% by mass, the color developability is not sufficient, and if the amount exceeds 99% by mass, the sealability may be deteriorated.

The polymer substance in the above laser color former is not particularly limited, and polyolefin, polyurethane, polycarbonate, polyester, rubber-modified monovinylidene, aromatic resin, polyetherimide, polyamide, polyimide, polyester carbonate, polyphenylene sulfide, polyamideimide. , polyesteramide, polyetherester, polyetherimideester, polyarylate, polymethylpentene, polysulfone, polyethersulfone, polystyrene, rubber-modified impact-resistant polystyrene, polyoxymethylene, styrene maleic anhydride copolymer, acrylonitrile styrene A wide range of resins can be selected including acrylate copolymers, acrylonitrile butadiene styrene copolymers (ABS), polyphenylene ethers, polyetherketones, chlorinated polymers, fluorinated polymers and liquid crystal polymers. In a more preferred embodiment, the polymeric material is selected from the group consisting of polyurethanes, polyamides, ABS, polycarbonates and rubber-modified monovinylidene aromatic resins and blends thereof. A most preferred polymeric material is a thermoplastic polyurethane resin. The amount of polymeric material can be mica or mica-like material, metal sulfides and the balance of one or more organic non-black pigments and other ingredients in the laser color former.

The mica or mica-like material in the laser color former described above can be any material that will produce a dark marking when combined with a polymeric resin and irradiated with laser light. Natural mica or synthetic mica can be used. Preferably, the mica or mica-like material is treated or doped with one or more metal compounds. Such metal compounds may be present as one or more thin colored or colorless layers or in discrete regions on the surface of the mica or mica-like material. Each array in each layer or discrete region may be optically coherent or optically incoherent. Preferably, the metal compound comprises one or more metal oxides, such as antimony and/or titanium and/or tin oxides, or iron and/or aluminum and/or silicon oxides. , preferably consists of one or more such metal oxides. Alternatively, mica or mica-like materials coated with bismuth oxychloride or treated with bismuth oxychloride may be used. The mica or mica-like material preferably has a density of 2.8-4.0 g/cm ³ . Preferably, it has a Mohs hardness of 2.5 to 4 and an oil absorption value of 35 to 70.0 grams per 100 grams of powder. Preferably, the amount of mica or mica-like substance is in the range of 0.05 to 1.9% by mass as the added amount of the laser coloring agent. More preferably, it is about 0.1 to about 0.5% by mass.

The metal sulfide in the laser color coupler described above can be any metal sulfide having any of the known stoichiometries, such _as MeS, _MeS2 , _Me2S3 or _Me3S4 (where Me is a metal of groups 1 to 14 of the periodic system, especially a transition metal of groups 9 to 12 of the periodic system), such as cadmium sulfide (II), cobalt sulfide (II), cobalt sulfide (II, III) (linnet), cobalt (III) sulfide, cobalt (IV) sulfide (catcherite), copper (I) sulfide (chalkosite), copper (II) sulfide (copper indigo), sulfide It can be iron(II), iron(III) sulfide, iron(IV) sulfide (pyrite, markasite), nickel(II) sulfide (needle nickelite) or zinc(II) sulfide. Mixed sulfides of two or more metals are also suitable. The metal sulfide may contain other components such as impurities and water of crystallization.

Said metal sulfides are preferably selected from the group consisting of cadmium sulfide, iron sulfide, zinc sulfide and mixed sulfides containing cadmium, iron or zinc as one of the metals. Among the iron sulfides, those with a yellowish appearance or those with a golden appearance are particularly suitable. Most preferably, the metal sulfide is a zinc sulfide such as albalith, sphalerite, maltraite, suctris, sphalerite or fibrous zincite. If the laser coupler is brightly colored, preferably a white metal sulfide (e.g. zinc sulfide) is used or a metal sulfide with a color similar to that of the laser coupler (e.g. zinc sulfide) is preferably used. If the laser color former is yellow-red, cadmium sulfide is used so that the addition of metal sulfides does not significantly discolor the laser color former.

The metal sulfides are preferably of small particle size (e.g. less than about 50 μm, especially less than about 20 μm) and most preferably of pigment grade (e.g. less than about 5 μm) such as C . I. Pigment Yellow 35, C.I. I. Pigment Yellow 37 or, in particular, C.I. I. Pigment White 7 and the like.

The amount of the metal sulfide present in the laser color former is preferably within the range of 500 to 2100 nm, the frequency is 1 to 100 kHz, the radiation level is 5 to 50 A, and the molded article is irradiated with the laser beam. is sufficient to cause a dark marking to be produced. More preferably, the amount of metal sulfide present in the laser color former is in the range of 0.05 to 2.9 mass % as the amount of the laser color former added. More preferably, it is 1.0 to 2.5% by mass.

Additional pigments, dyes and/or inert extenders can be added to the laser color formers described above, depending on the color desired. The types and amounts of these additives are appropriately determined according to the end use. In a particularly preferred composition, the color of products molded with the composition is pink, red, yellow, orange, yellow-green, lilac, mid-blue to light blue or turquoise, due to the use of pigments. make it Such pigments are preferably organic or inorganic non-black pigments. The pigment is best present in an amount of 0.01 to 9.9% by mass as the amount added to the laser coloring agent.

Further additives can be incorporated into the laser color coupler to improve the molding properties of the resin or the environmental compatibility of the resulting molded article. Useful additives include antioxidants, antistatic agents, light stabilizers, UV absorbers, neutralizers, rust inhibitors, lubricants, flame retardants, nucleating agents, dispersants, processing stabilizers and fluidity. improvers, etc. The types and amounts of these additives are well known to those skilled in the art and are appropriately determined according to the end use.

The laser color former described above can be prepared by mixing the above polymer substance, metal sulfide and mica or mica-like substance and, if necessary, further additives. There are no restrictions on the method of compounding, and any known technique can be employed. Preferably, the compounding process is carried out by high shear Z-blade mixing or by extrusion (single screw extrusion or twin counter-rotating or twin co-rotating screw extrusion). However, it is also possible to simply mix or blend the components, especially if sufficient homogenization is ensured in the subsequent processing steps. The prepared laser coloring agent is used as a masterbatch and kneaded with a polyolefin resin to obtain a raw material for the laser printing film 1 or the laser coloring layer 11, and this raw material is formed into a film by film forming or extrusion molding.

[Polyolefin resin layers 12 and 13]
The first polyolefin resin layer 12 and the second polyolefin resin layer 13 of the film for laser printing 10 are made of polyolefin resin. The polyolefin resin can be one or more selected from low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, random polypropylene, homopolypropylene and block polypropylene. Among these resins, low-density polyethylene and linear low-density polyethylene are preferable when providing low-temperature sealability, and random polypropylene, homopolypropylene, block polypropylene, and high-density polyethylene are preferable for applications requiring heat resistance. is preferred.

The first polyolefin resin layer 12 and the second polyolefin resin layer 13 may be made of the same material or different materials. For example, the first polyolefin-based resin layer 12 is made of a material having higher heat resistance than the polyolefin-based resin in the laser coloring layer 11 from the viewpoint of heat resistance as an outer layer, and the second polyolefin-based resin layer 13 is used as an inner layer with sealing properties. From the viewpoint of, it can be a material excellent in sealing performance.

[Method for producing a film for laser printing]
Next, a method for producing the film for laser printing of the present invention will be described. The above-described laser printing film 1 of one embodiment of the present invention is kneaded with a laser coloring agent and a polyolefin resin as a masterbatch, and then subjected to a known film forming method such as an inflation film forming method or a cast film forming method. It can be manufactured by forming a film with.
The thickness of the film for laser printing 1 produced by the above method is not particularly limited, and can be about 20 to 200 μm. More preferably, the thickness is 30 to 150 μm, which is thinner than a conventional film for laser printing comprising a substrate layer, a laser coloring layer and a sealant layer.

Further, the laser printing film 10 of another embodiment of the present invention is obtained by co-extrusion of the material of the first polyolefin resin layer 12, the material of the laser coloring layer 11, and the material of the second polyolefin resin 13. It can be manufactured by
The thickness of the film for laser printing 10 produced by the above method is not particularly limited, and can be about 20 to 200 μm. More preferably, the thickness is 30 to 150 μm, which is thinner than a conventional film for laser printing comprising a substrate layer, a laser coloring layer and a sealant layer.

[Applications of the film for laser marking]
The film for laser printing of the present invention can be applied to various packaging materials, labels, cards, etc. in the form of the film. In addition, the film for laser printing of the present invention can be applied to various packaging materials, labels, cards, etc. in the form of a laminate in which another functional film is laminated.

[Laser marking method]
The laser printing film 1 and the laser printing film 10 are printed by irradiating a pulsed laser beam from a laser printer. Printing is performed using YAG (yttrium (Y), aluminum (A), garnet (G)) laser light (wavelength = 1.064 µm) and YVO ₄ (yttrium vanadate) laser light (wavelength = 1.064 µm). is preferred. These lasers have the property of being able to pass through transparent materials, and by using this property, the generation of smoke, etc. during printing can be suppressed, and the color density and the effect on the film can be adjusted. . As a result, even if a laser printed image is formed, it is possible to form an extremely clear laser printed image without holes or the like.

The pulse conditions for the laser printer are, for example, a YVO ₄ laser machine (Keyence MD-V9600) with an average output of 0.8 to 5 W, more preferably 1.2 to 2 W, a Q switch frequency of 10 to 30 kHz, and a scan speed of 300 to 300. Pulse conditions of 4000 mm/s, more preferably 1500-4000 mm/s are used. By printing under these conditions, high-speed printing is possible without forming holes in the laser-printing film, and a clear printed image can be obtained.

EXAMPLES The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

(Example 1)
5% by mass of a laser coloring agent masterbatch (PE-RM 17K4471N-L, Dainichiseika Kogyo Co., Ltd.) was added to linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.), and the thickness was 60 μm at 150 ° C. to obtain a film for laser printing of Example 1.

(Example 2)
Linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.) for the outer layer, laser colorant masterbatch (PE-RM 17K4471N-L, Dainichiseika Kogyo Co., Ltd.) for the intermediate layer, linear low-density polyethylene (SP2020) , Prime Polymer Co., Ltd.), the inner layer is a linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.), and the thickness ratio of each layer is 1: 1: 1 by coextrusion. A film for laser printing of Example 2 was obtained by forming a film with a thickness of 60 μm.

(Example 3)
5% by mass of laser colorant masterbatch (PE-RM 17K4471N-L, Dainichi Seika Kogyo Co., Ltd.) was added to linear low-density polyethylene (SP2540, Prime Polymer Co., Ltd.), and the thickness was 60 μm at 220 ° C. to obtain a laser-printing film of Example 3.

(Example 4)
Add 5% by mass of polypropylene-based laser colorant masterbatch (PE-RM 17K4471N-L, Dainichiseika Kogyo Co., Ltd.) to random polypropylene (F227D, Prime Polymer Co., Ltd.) and cast at 220 ° C. to a thickness of 60 μm. A film for laser printing of Example 4 was obtained.

(Comparative example 1)
Linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.) was blown into a 60 μm-thick film at 150° C. to obtain a film for laser printing of Comparative Example 1.

(Example 5)
2% by mass of a laser colorant masterbatch (PE-RM 17K4471N-L, Dainichi Seika Kogyo Co., Ltd.) was added to linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.), and the thickness was 60 μm at 150 ° C. to obtain a film for laser printing of Example 5.

(Comparative example 2)
Linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.) was blown into a 60 μm-thick film at 150° C. to obtain a sealant film. A printing ink type laser colorant (Elbima Z117, Toyo Ink Co., Ltd.) was printed on the surface of the sealant film to obtain a laminate of Comparative Example 2.

[Test method]
The films for laser printing of Examples 1 to 5 and Comparative Examples 1 and 2 were irradiated with a YVO ₄ laser from the surface layer side under the following conditions to form a laser printed image to obtain printed bodies.

(Laser irradiation conditions)
YVO ₄ laser machine (Keyence MD-V9600 with average output of 2.4 W, Q switch frequency of 10 kHz, scan speed of 1500 mm/s)
The colored line width was measured for the obtained laser printed image. In addition, the printability was evaluated by confirming the appearance after irradiation with laser light. Furthermore, the amount of residual solvent in the film for laser printing was measured with a gas chromatograph mass spectrometer (Shimadzu Corporation).

Table 1 shows the test results. In Table 1, the evaluation of printability was as follows: ◯ indicates that the colored line width was 0.5 mm or more and was clearly visible; Δ: colored or not visible; and ×: unprintable. be.

From Table 1, the films of Examples 1 to 5 had almost transparent light transmittance, good printability, and wide and clear line width. In particular, Examples 1 to 4 were excellent in printability. In addition, it was clarified that the residual solvent is zero, and that it is suitable for applications such as beverages in which residual solvent is avoided as much as possible among packaging materials. On the other hand, Comparative Example 1 could not be printed because it did not contain a laser coloring agent. In Comparative Example 2, since the laser coloring agent contained titanium oxide, the entire film was white, and the solvent remained.

Although the film for laser printing of the present invention has been specifically described above using the embodiments and examples, the film for laser printing of the present invention is not limited to the description of these embodiments and examples. Numerous modifications are possible without departing from the gist of the present invention.

1, 10 laser printing film 11 laser coloring layer 12 first polyolefin resin layer (outer layer)
13 Second polyolefin resin layer (inner layer)

Claims (5)

Contains polyolefin resin and laser coloring agent,
A film for laser printing, wherein the laser coloring agent comprises a polymeric substance, a mica or mica-like substance, a metal sulfide and one or more organic non-black pigments . Equipped with a laser coloring layer containing a polyolefin resin and a laser coloring agent ,
A film for laser printing, wherein the laser coloring agent comprises a polymeric substance, a mica or mica-like substance, a metal sulfide and one or more organic non-black pigments . 3. The film for laser printing according to claim 2, further comprising a layer made of polyolefin resin overlaid on said laser coloring layer. 0.05 to 1.9% by mass of the mica or mica-like substance, 0.05 to 2.9% by mass of the metal sulfide, and one or more of the above 4. The film for laser printing according to any one of claims 1 to 3, containing 0.01 to 9.9% by mass of the organic non-black pigment. 4. The polyolefin resin is one or more selected from low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, random polypropylene, homopolypropylene and block polypropylene. The film for laser marking according to any one of .

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