JP7375311B2 - Laminate for laser printing - Google Patents

Description

The present invention relates to a laminate for laser printing.

BACKGROUND OF THE INVENTION Conventionally, text information such as the manufacturing site, manufacturing date, and symbols are sometimes written on the surface of packaging materials for foods, medicines, etc., either before the contents are contained or after the contents are contained and sealed. In order to write such character information, it has been printed using a thermal printer or an inkjet printer, or a separately printed label has been attached. However, in the case of packages with irregularly shaped surfaces or flexible packages containing contents that are vulnerable to impact, mechanical printing methods using thermal heads such as thermal printers are not appropriate, and inkjet printers are Printing using this method has problems such as the print disappearing or coming off due to oily contents adhering to the print area or being rubbed during handling or transportation. Furthermore, attaching a separately printed label increases the cost of attaching the label.

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 printing surface of the package with a laser beam. A film as a packaging material for laser printing used for printing by laser marking includes a base material layer, a laser coloring layer, and a sealant layer (Patent Document 1). The laser coloring layer, on which a printed image is formed by irradiation with laser light, is not exposed on the outermost surface, but is covered with a base layer that serves as a surface protection layer made of various films, etc. Printing was done by irradiating laser light.

Patent No. 6126420 specification

However, the film used for the above-mentioned laser printing, which is used as packaging material, etc., has a total of three layers: a base material layer, a laser coloring layer formed by printing, and a sealant layer, so it has a large thickness. It had to be thick, and the manufacturing cost was also high. If the film consists of a total of two layers, a laser coloring layer and a sealant layer, the laser coloring layer will be the outermost layer, so there is a risk that the printing will disappear or be scratched during handling or transportation. There were problems such as detachment. Furthermore, since the laser coloring layer is formed by printing, the organic solvent contained in the ink may remain.

The present invention advantageously solves the above problems, and provides a laminate for laser printing that can be made thinner, can reduce manufacturing costs, and can prevent organic solvents from remaining. The purpose is to

As a result of intensive research into laminates for laser printing, the inventors found that by making the laser coloring layer a layer containing a laser coloring agent in a resin, laser printing is possible and the printing does not occur due to scratches, etc. It was discovered that the organic solvent does not disappear or separate, and that no organic solvent remains, leading to the present invention.

The laminate for laser printing of the present invention based on the above knowledge includes a light-shielding layer and a laser coloring layer containing a polyolefin resin and a laser coloring agent, wherein the laser coloring agent is a polymeric material, mica or mica-like material, or a metal. It contains sulfide and one or more organic non-black pigments.

The laminate for laser printing of the present invention may include a layer made of polyolefin resin, superimposed on the laser coloring layer. The above-mentioned laser coloring agent contains the above-mentioned mica or mica-like substance in an amount of 0.05 to 1.9% by mass, the above-mentioned metal sulfide in an amount of 0.05 to 2.9% by mass, and one or more of the above-mentioned types. It is preferable that the organic non-black pigment is contained in an amount of 0.01 to 9.9% by mass. The polyolefin 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 laminate of the present invention, the thickness can be reduced, manufacturing costs can be reduced, and organic solvent can be prevented from remaining.

FIG. 1 is a schematic cross-sectional view of an embodiment of a laser coloring layer of a laminate for laser printing of the present invention. It is a typical sectional view of another embodiment of the laser coloring layer of the laminated body for laser printing of the present invention. FIG. 1 is a schematic cross-sectional view of one embodiment of a laminate for laser printing of the present invention. It is a typical sectional view of another embodiment of the laminated body for laser printing of the present invention. It is a typical sectional view of another embodiment of the laminated body for laser printing of the present invention.

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

The polyolefin resin is, for example, polyethylene, which will be described later, and is a resin used as a sealant for packaging materials. Therefore, since the laser coloring layer 1 contains the polyolefin resin, even a single layer has an effect as a sealant. Therefore, even when the laser coloring layer 1 is used as a packaging material and a plurality of layers are stacked to form a laminate, the packaging material can be sealed by heat sealing.

Further, the laser coloring layer 1 contains a laser coloring agent. Rather than forming the laser coloring agent on the surface of other layers by printing, etc., by including it in the layer as laser coloring layer 1, the printing will disappear even if it is rubbed during handling or transportation as a packaging material. There are no problems such as separation or detachment. Since the polyolefin resin can transmit laser light, even if the laser coloring layer 1 contains a laser coloring agent, it can be colored by the laser coloring agent.

Therefore, the laser coloring layer 1 does not necessarily require a separate protective layer or base layer for protecting the laser coloring layer. Further, it is not necessarily necessary to separately provide a sealant layer. Therefore, since a protective layer, a base material layer, and a sealant layer are not necessary, the thickness when used as a packaging material can be reduced, and manufacturing costs can be suppressed.

FIG. 2 shows a schematic cross-sectional view of an embodiment of the laser coloring layer laminate, which is a characteristic part of the laser printing laminate of the present invention. In FIG. 2, the laser coloring layer laminate 10 is a multilayer film, and in the example shown in FIG. It includes 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 coloring layer laminate 10 shown in FIG. 2, the portion including the coloring layer in the laser printing laminate of the present invention is not limited to a single layer, but may also be a multilayer (multiple layers). can.

The laser coloring layer 11 of the laser coloring layer laminate 10 contains a polyolefin resin and a laser coloring agent. The polyolefin resin of the laser coloring layer 11 is, for example, polyethylene, similar to the laser coloring layer 1 shown in FIG. 1, and is a resin used as a sealant for packaging materials. Therefore, since the laser color forming layer 11 contains a polyolefin resin, it is in close contact with the first polyolefin resin layer 12 and also with the second polyolefin resin layer 13, so that the laser color forming layer 11 has a three-layer structure as a whole. It can be made into a coloring layer laminate 10. Although it depends on the manufacturing method, the thickness of the laser coloring layer laminate 10 can be reduced, for example, by coextrusion, similar to the laser coloring layer 1 shown in FIG.

Note that the laser coloring layer laminate having a multilayer structure is not limited to the three-layer structure shown in FIG. It may have a two-layer structure including the laser coloring layer 11, or it may have a four-layer structure including the laser coloring layer 11.

Further, the laser coloring layer laminate 10 contains a laser coloring agent in the laser coloring layer 11. By including a laser coloring agent in the laser coloring layer 11 of the laser coloring layer laminate 10 having a multilayer structure, even if the laser coloring layer 11 is the outermost layer, it will not be scratched during handling or transportation as a packaging material. However, problems such as printing disappearing or coming off do not occur. The polyolefin resins 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 coloring layer laminate 10 contains a laser coloring agent, the laser coloring agent is Color can be developed by

Although it depends on the coloring mechanism of the laser coloring agent in the laser coloring layer 11, the first polyolefin resin layer 12 and the second polyolefin resin layer 13 do not contain a laser coloring agent, and the laser coloring layer 11 is laser colored. Embodiments containing agents are preferred. With this aspect, color development is better than when each layer contains a laser coloring agent, and in particular, when a suitable laser coloring agent described later is used, it is possible to print clearly.

Further, since the laser coloring layer 11 contains polyolefin resin, it can be used as a sealant if necessary. Furthermore, since the laser coloring layer laminate 10 includes a first polyolefin resin layer 12 and a second polyolefin resin layer 13 in addition to the laser coloring layer 11, the laser coloring layer laminate 10 can be used as a packaging material. When used, it is possible to improve the sealing performance when multiple sheets are stacked and heat-sealed.

From the above, the laser coloring layer laminate 10 can be made thinner when used as a packaging material, and manufacturing costs can be suppressed.

One embodiment of the laser printing laminate of the present invention is shown in a schematic cross-sectional view in FIG. The laser printing laminate 20 shown in FIG. 3 includes the laser coloring layer 1 shown in FIG. The sealant layer 22 is formed on the other surface of the sealant layer 22. The base material layer 21 and the sealant layer 22 are not particularly limited, as long as at least one of the base material layer 21 and the sealant layer 22 is a layer that can transmit laser light. It should be noted that the laser printing laminate 20 shown in FIG. It may be composed of two layers, layer 1 and sealant layer 22, or it may be a laminate of four or more layers, including laser coloring layer 1, base material layer 21, sealant layer 22, and other layers.

Another embodiment of the laser printing laminate of the present invention is shown in a schematic cross-sectional view in FIG. The laser printing laminate 30 shown in FIG. 4 includes the laser coloring layer laminate 10 shown in FIG. A sealant layer 32 is formed on the other surface of the layer laminate 10. The base material layer 31 and the sealant layer 32 are not particularly limited as long as at least one of the base material layer 31 and the sealant layer 32 is a layer that can transmit laser light. Note that the laser printing laminate 30 shown in FIG. 4 is an example, and the laser printing laminate of the present invention may be composed of two layers, the laser coloring layer laminate 10 and the base material layer 31. It may be composed of two layers, the laser coloring layer laminate 10 and the sealant layer 32, or it may be a laminate of four or more layers comprising the laser coloring layer laminate 10, the base material layer 31, the sealant layer 32, and other layers. There may be.

Another embodiment of the laser printing laminate of the present invention is shown in a schematic cross-sectional view in FIG. Another embodiment of the laser printing laminate of the present invention is shown in a schematic cross-sectional view in FIG. The laser printing laminate 40 shown in FIG. 5 includes the laser coloring layer 1 shown in FIG. This is a laminate including a sealant layer 42 formed on the other surface, and a light shielding layer 43 formed between the base layer 41 and the laser coloring layer 1. The base material layer 41 and the sealant layer 42 are not particularly limited. The sealant layer 42 is a sealant layer that can transmit laser light. The light shielding layer 43 is a layer for making the coloring of the laser coloring layer 1 such as aluminum foil or aluminum vapor deposition film invisible from the base material layer 41 side.

Laser printing is performed by irradiating laser light from the sealant layer 4 side to color the laser coloring layer 1, and heat-seal the two laser printing laminates 40 by overlapping them with their sealant layers 42 facing each other. This may be a packaging container, for example a packaging bag. Although the laser printing is not visible before the packaging bag is opened, the laser printing can be seen when the packaging bag is opened and the inside of the packaging bag is looked into. Therefore, the laser printing laminate 40 of this embodiment can be utilized for determining the authenticity of the contents of a packaging bag and for preventing counterfeiting.

Each layer of the laser coloring layer 1 and the laser coloring layer laminate 10 used in the laser printing laminates 20, 30, and 40 will be specifically described below.

[Laser coloring layers 1, 11]
The laser coloring layer 1 and the laser coloring layer 11 are layers that develop color upon receiving laser light, 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 sealing properties, even a single layer like the laser coloring layer 1 can be heat-sealed as a packaging material. Among these resins, when imparting low-temperature sealing properties, low-density polyethylene and linear low-density polyethylene are preferred; for applications requiring heat resistance, random polypropylene, homopolypropylene, block polypropylene, and high-density polyethylene are preferred. is preferred.

Preferably, the laser coloring agent contains a polymeric substance, mica or a mica-like substance, a metal sulfide, and one or more organic non-black pigments. A laser coloring agent containing such a component is described in, for example, Japanese Patent No. 4,695,085. The laser color forming agent, which includes a polymeric material, mica or mica-like material, metal sulfide, and one or more organic non-black pigments, aggregates in a layer and exhibits a dark color when exposed to the laser, thereby producing color. The laser color forming agent containing the above components can be kneaded with the above-mentioned polyolefin resin as a master batch to form a film, thereby producing a film of the laser color forming layer 1 or the laser color forming layer 11.

The laser coloring agent containing the above components is not used to form the laser coloring layer 1 or the laser coloring layer 11 by printing, and therefore does not contain the organic solvent contained in the ink used for printing. Therefore, the laser coloring layer 1 or the laser coloring layer laminate 10 does not contain any residual solvent. Therefore, it has the effect of being suitable for applications in which it is not desirable for organic solvents to remain, such as packaging materials for BIBs (Bag in Boxes) used for 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, and the laser heats the titanium oxide in the layer, causing the titanium oxide to The markings were made by carbonizing and discoloring the surrounding constituent materials. In the conventional laser coloring layer printed with ink containing titanium oxide, the laser coloring layer shows an overall white color due to the color of the titanium oxide contained in the layer, and therefore, it is suitable as a laser printing film as a whole. It showed a white color. On the other hand, the laser color forming agent containing the above-mentioned polymeric substance, mica or mica-like substance, metal sulfide, and one or more organic non-black pigments does not contain titanium oxide, so it is not light-transmissive before laser printing. This has the effect of making it possible to produce a film with high transparency and near transparency.

The laser coloring agent containing the above components is preferably contained in a single layer (laser coloring layer 1 or laser coloring layer 11) in an amount of 3 to 99% by mass as a masterbatch. If it is less than 3% by mass, the coloring property will not be sufficient, and if it exceeds 99% by mass, there is a risk that the sealing performance will be deteriorated.

The polymeric substances in the laser coloring agent mentioned above are not particularly limited, and include polyolefin, polyurethane, polycarbonate, polyester, rubber-modified monovinylidene, aromatic resin, polyetherimide, polyamide, polyimide, polyester carbonate, polyphenylene sulfide, polyamideimide. , polyester amide, polyether ester, polyetherimide ester, polyarylate, polymethylpentene, polysulfone, polyether sulfone, polystyrene, rubber modified high impact 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, polyether ketones, chlorinated polymers, fluorinated polymers, liquid crystal polymers, and the like. In a more preferred embodiment, the polymeric material is selected from the group consisting of polyurethane, polyamide, ABS, polycarbonate and rubber modified monovinylidene aromatic resins and blends thereof. The most preferred polymeric material is a thermoplastic polyurethane resin. The amount of polymeric material can be the remaining amount of mica or micaceous material, metal sulfide, and one or more organic non-black pigments and other components in the laser color former.

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

The metal sulfide in the laser color former described above can be any metal sulfide with any known stoichiometry, such as MeS, MeS ₂ , Me ₂ S ₃ or Me 3 S ₄ (wherein Me is a metal of groups 1 to 14 of the periodic system, in particular a transition metal of groups 9 to 12 of the periodic system), such as cadmium(II) sulfide, cobalt(II) sulfide, cobalt(II) sulfide, III) (linnet), cobalt(III) sulfide, cobalt(IV) sulfide (cachierite), copper(I) sulfide (chalkosite), copper(II) sulfide (copper indigo), sulfide It can be iron(II), iron(III) sulfide, iron(IV) sulfide (pyrite, marcasite), nickel(II) sulfide (goethickelite), 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.

The metal sulfide is 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 or golden appearance are particularly suitable. Most preferably, the metal sulfide is a zinc sulfide such as albalith, sphalerite, maltraite, sactolith, sphalerite or sphalerite. If the laser color former is brightly colored, preferably a white metal sulfide (e.g. zinc sulfide) or a metal sulfide of a color similar to the color of the laser color former (e.g. When the laser coloring agent is yellow-red, cadmium sulfide is used to prevent the laser coloring agent from significantly changing color even when a metal sulfide is added.

The metal sulfide preferably has a small particle size (e.g., less than about 50 μm, especially less than about 20 μm), and most preferably is of pigment grade (e.g., less than about 5 μm), such as C ．． I. Pigment Yellow 35, C. I. Pigment Yellow 37 or especially C.I. I. Pigment White 7, etc.

The amount of the metal sulfide present in the laser coloring agent is preferably within the range of 500 to 2100 nm, and the amount on the molded article when the molded article is irradiated with laser light at a frequency of 1 to 100 kHz and a radiation level of 5 to 50 A. in sufficient quantity to produce dark markings. More preferably, the amount of metal sulfide present in the laser coloring agent is in the range of 0.05 to 2.9% by mass as the amount of the laser coloring agent added. More preferably, it is 1.0 to 2.5% by mass.

Depending on the desired color, additional pigments, dyes and/or inert fillers can be added to the laser color formers described above. The type and amount of these additives are appropriately determined according to the end use. In particularly preferred compositions, pigments are used such that the color of the product molded with the composition is pink, red, yellow, orange, yellow-green, lilac, mid-blue to light blue or cerulean. do it like this. 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 weight of the laser color former.

Further additives can be incorporated into the laser color former 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 flowability agents. There are enhancers, 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 above-mentioned laser coloring agent can be prepared by mixing the above-mentioned polymeric substance, metal sulfide, and mica or mica-like substance, and, if necessary, adding further additives. There are no restrictions on the blending method, 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 screw extrusion 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 subsequent processing steps. The prepared laser coloring agent is used as a masterbatch and kneaded with a polyolefin resin to form a raw material for the laser coloring layer 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, 13]
The first polyolefin resin layer 12 and the second polyolefin resin layer 13 of the laser coloring layer laminate 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, when imparting low-temperature sealing properties, low-density polyethylene and linear low-density polyethylene are preferred; for applications requiring heat resistance, random polypropylene, homopolypropylene, block polypropylene, and high-density polyethylene are preferred. is preferred.

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

[Base material layer]
Next, the base material layers 21, 31, and 41 of the laser printing laminate shown in FIGS. 3, 4, and 5 will be explained.
As the base material layer, a resin film that constitutes a normal packaging material can be used as appropriate. Specifically, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, polyvinyl alcohol, polyacrylonitrile, polycarbonate, ethylene-vinyl acetate copolymer, ionomer, ethylene-(meth)acrylic acid copolymers, ethylene-(meth)ethyl acrylate copolymers, ethylene-propylene copolymers, methylpentene, polybutene, acid-modified polyolefin resins, polyamide resins, polystyrene resins, low-crystalline saturated polyesters or Crystalline polyester resins, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), tetrafluoroethylene-ethylene copolymer (ETFE), polytetrafluoroethylene (PTFE), MXD6, etc. A film consisting of can be used.
Among the resin films listed above, polyester resins such as polyethylene terephthalate (hereinafter also referred to as "PET"), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polybutylene naphthalate (PBN); polycapron Polyamide resins such as amide (nylon 6), polyhexamethylene adipamide (nylon 66), and poly-p-xylylene adipamide (MXD6 nylon); polyolefin resins such as polyethylene and polypropylene are preferred. In particular, PET film is more preferable for the base layers 21, 31, and 41 because it has high transparency, excellent dimensional stability, and heat resistance. The polyester resin, polyamide resin and polyolefin resin listed above may be a mixture thereof.
The base material layer may be a multilayer film in which two or more resin films are laminated. In the case of a multilayer film, each layer may have the same composition or different compositions.

[Adhesive layer]
The base material layers 21, 31, and 41 and the laser coloring layer 1, the first polyolefin resin layer 12, and the light-shielding layer 43 can be bonded together using an adhesive layer (not shown) (dry lamination).
For the adhesive layer, any adhesive having excellent adhesive strength and heat resistance can be used, such as a laminating adhesive such as a urethane adhesive, a vinyl adhesive, an acrylic adhesive, or an epoxy adhesive. The amount of adhesive to be applied is appropriately set so that the thickness of the adhesive is 0.1 g/m ² to 10 g/m ² as a dry film, more preferably 0.1 g/m ² to 5 g/m ² . good. If necessary, a surface treatment agent such as an anchor coating agent may be applied to the base layer side in advance, or a pretreatment such as corona treatment may be performed.

[Method for manufacturing a laminate for laser printing]
Next, a method for manufacturing a laminate for laser printing according to the present invention will be explained. A laminated body 20 for laser printing according to an embodiment of the present invention shown in FIG. 3 includes a base material layer 21, a laser coloring layer 1, and a sealant layer 22 that are laminated by a known method such as extrusion molding or dry lamination. It can be manufactured by Further, in the laser printing laminate 30 according to the embodiment of the present invention shown in FIG. It can be manufactured by laminating layers by dry laminating. Further, in the laser printing laminate 40 according to the embodiment of the present invention shown in FIG. It can be manufactured by laminating layers by extrusion molding or dry lamination.
A method of manufacturing the laser coloring layer 1, which is characteristic of the present invention, will be explained. It can be manufactured by kneading a laser coloring agent and a polyolefin resin as a masterbatch, and then forming a film using a known film forming method, such as an inflation film forming method or a cast film forming method.
The thickness of the laser coloring layer 1 manufactured by the above method is not particularly limited, and can be approximately 20 to 200 μm. More preferably, it is 30 to 150 μm, which allows it to be thinner than a conventional laser printing film comprising a base material layer, a laser coloring layer, and a sealant layer.

Further, the laser coloring layer laminate 10 can be manufactured by co-extruding 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. can.
The thickness of the laser coloring layer laminate 10 produced by the above method is not particularly limited, and can be approximately 20 to 200 μm. More preferably, it is 30 to 150 μm, which allows it to be thinner than a conventional laser printing film comprising a base material layer, a laser coloring layer, and a sealant layer.

[Applications of laminate for laser printing]
The laser printing laminate of the present invention can be applied to various packaging materials, labels, cards, etc. in the form of a film. Furthermore, the laminate 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 printing method]
Printing is performed by irradiating the laser printing laminate 20, the laser printing laminate 30, and the laser printing laminate 40 with pulsed laser light from a laser printer. Printing is performed using YAG (yttrium (Y), aluminum (A), garnet (G)) laser light (wavelength = 1.064 μm), YVO ₄ (yttrium vanadate) laser light (wavelength = 1.064 μm). It is preferable. These lasers have the property of transmitting through transparent materials, and by utilizing 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 include, for example, a YVO ₄ laser machine (Keyence MD-V9600) with an average output of 0.8 to 5 W, 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 performing printing under these conditions, high-speed printing is possible without making holes in the laser printing laminate, and a clear printed image can be obtained.

EXAMPLES Hereinafter, the present invention will be explained in more detail using Examples, but the present invention is not limited to these Examples in any way.

(Example 1)
3% 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 mixture was heated to 150°C to a thickness of 60 μm. Inflation film formation was carried out to obtain the laser coloring layer film of Example 1. The above film was subjected to corona treatment, and the corona treated surface and the corona surface of biaxially oriented polyethylene terephthalate (E5100, Toyobo Co., Ltd., thickness 12 μm) were bonded with a two-component curable urethane adhesive (RU-77T/H- 7. The laminate of Example 1 was obtained by laminating with Rock Paint Co., Ltd.).

(Example 2)
The outer layer is made of linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.), and the middle layer is made of linear low-density polyethylene (SP2020) with a masterbatch of laser colorant (PE-RM 17K4471N-L, Dainichiseika Kogyo Co., Ltd.). , Prime Polymer Co., Ltd.), and the inner layer was made of linear low density polyethylene (SP2020, Prime Polymer Co., Ltd.), and the thickness ratio of each layer was 1:1:1 by coextrusion. A film having a thickness of 60 μm was formed to obtain a film of the laser coloring layer laminate of Example 2. The above film was subjected to corona treatment, and the corona surface of biaxially oriented polyethylene terephthalate (E5100, Toyobo Co., Ltd., thickness 12 μm) was bonded with a two-component curable urethane adhesive (RU-77T/H-7, Rock Paint). The laminate of Example 2 was obtained by laminating the laminate through a laminate (Co., Ltd.).

(Example 3)
3% by mass of a laser colorant masterbatch (PE-RM 17K4471N-L, Dainichiseika Kagyo Co., Ltd.) was added to linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.), and the mixture was heated to 150°C to a thickness of 60 μm. Inflation film formation was carried out to obtain a film with a laser coloring layer of Example 3. The above film was subjected to corona treatment. The corona surface of biaxially oriented polyethylene terephthalate (E5100, Toyobo Co., Ltd., thickness 12 μm) and aluminum foil (thickness 7 μm) were bonded with a two-component urethane adhesive (RU-77T/H-7, Rock Paint Co., Ltd.) ), and then the non-laminated surface of the aluminum and the corona-treated surface of the film are laminated with a two-component curable urethane adhesive (RU-77T/H-7, Rock Paint Co., Ltd.). A laminate of Example 3 was obtained.

(Example 4)
The outer layer is a linear low density polyethylene (SP2020, Prime Polymer Co., Ltd.), the middle layer is a laser printing masterbatch (PE-RM 17K4471N-L, Dainichiseika Kagyo Co., Ltd.) added at 3% by mass, and the inner layer is a linear one. A film was formed using low density polyethylene (SP2020, Prime Polymer Co., Ltd.) at a layer ratio of 1:1:1 and a thickness of 60 μm to obtain a film of the laser coloring layer laminate of Example 4. The above film was subjected to corona treatment. The corona surface of biaxially oriented polyethylene terephthalate (E5100, Toyobo Co., Ltd., thickness 12 μm) and aluminum foil (thickness 7 μm) were bonded with a two-component urethane adhesive (RU-77T/H-7, Rock Paint Co., Ltd.) ), and then the non-laminated side of the aluminum foil and the corona-treated side of the film are laminated using a two-component curable urethane adhesive (RU-77T/H-7, Rock Paint Co., Ltd.). A laminate of Example 4 was obtained.

(Comparative example 1)
Linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.) was film-formed by inflation to a thickness of 60 μm at 150° C. to obtain a film containing no laser coloring agent. The above film was subjected to corona treatment, and the corona surface of biaxially oriented polyethylene terephthalate (E5100, Toyobo Co., Ltd., thickness 12 μm) was bonded with a two-component curable urethane adhesive (RU-77T/H-7, Rock Paint). A laminate of Comparative Example 1 was obtained by laminating the laminate through a laminate (Comparative Example 1).

(Example 5)
2% by mass of a laser colorant masterbatch (PE-RM 17K4471N-L, Dainichiseika Kogyo Co., Ltd.) was added to linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.), and the mixture was heated to 150°C to a thickness of 60 μm. Inflation film formation was carried out to obtain a film with a laser coloring layer of Example 5. The above film was subjected to corona treatment, and the corona surface of biaxially oriented polyethylene terephthalate (E5100, Toyobo Co., Ltd., thickness 12 μm) was bonded with a two-component curable urethane adhesive (RU-77T/H-7, Rock Paint). The laminate of Example 5 was obtained by laminating the laminate through a laminate (Co., Ltd.).

(Comparative example 2)
A sealant film was obtained by inflation-forming linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.) at 150° C. to a thickness of 60 μm.
Elbima Z117 (Toyo Ink Co., Ltd.), a printing ink type laser coloring agent, is printed on a PET base material (thickness 12 μm), and the printed surface and the corona-treated film are bonded together using a two-component curable urethane adhesive (RU). -77T/H-7, manufactured by Rock Paint Co., Ltd., to obtain a laminate of Comparative Example 2.

(Comparative example 3)
Comparative Example 3 is an example that does not have a laser coloring layer but has a light shielding layer.
A sealant film was obtained by inflation-forming linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.) at 150° C. to a thickness of 60 μm.
The corona surface of biaxially oriented polyethylene terephthalate (E5100, Toyobo Co., Ltd., thickness 12 μm) and aluminum foil (thickness 7 μm) were bonded with a two-component urethane adhesive (RU-77T/H-7, Rock Paint Co., Ltd.) ), and then the non-laminated side of the aluminum foil and the corona-treated side of the film were bonded together using a two-component curable urethane adhesive (RU-77T/H-7, Rock Paint Co., Ltd.). A laminate of Comparative Example 3 was obtained by laminating.

(Example 6)
2% by mass of laser-printed MB (PE-RM 17K4471N-L, Dainichiseika Kagyo Co., Ltd.) was added to linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.), and it was made by inflation at 150°C to a thickness of 60 μm. A sealant film was obtained.
The corona surface of biaxially oriented polyethylene terephthalate (E5100, Toyobo Co., Ltd., thickness 12 μm) and aluminum foil (thickness 7 μm) were bonded with a two-component urethane adhesive (RU-77T/H-7, Rock Paint Co., Ltd.) ), and then the non-laminated surface of the aluminum foil and the corona-treated surface of the film are laminated using a two-component curable urethane adhesive (RU-77T/H-7, Rock Paint Co., Ltd.). In this way, a laminate of Example 6 was obtained.

(Comparative example 4)
A sealant film was obtained by inflation-forming linear low-density polyethylene (SP2020, Prime Polymer Co., Ltd.) at 150° C. to a thickness of 60 μm. Corona treatment was performed on the surface of the above film.
Elbima Z117, a laser colored ink, is printed on a PET base material (thickness 12 μm), and the printed surface and aluminum foil (thickness 7 μm) are bonded together using a two-component curable urethane adhesive (RU-77T/H-7, Lock). Paint Co., Ltd.), and then the non-laminated side of the aluminum foil and the corona-treated film are bonded together using a two-component curable urethane adhesive (RU-77T/H-7, Rock Paint Co., Ltd.). ) to obtain a laminate of Comparative Example 4.

[Test method]
The laser printing laminates of Examples 1 to 6 and Comparative Examples 1 to 4 were irradiated with YVO ₄ laser from the surface side under the following conditions to form laser printed images to obtain printed bodies.

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

The test results are shown in Table 1. In Table 1, the evaluation of printability is as follows: ○ indicates that the colored line width was 0.5 mm or more and was clearly visible, △ indicates that the line was colored or could not be seen, and × indicates that it could not be printed. be.

From Table 1, in Examples 1 to 6, the films had near-transparent light transmittance, good printing properties, and clear line widths. In particular, Examples 1 to 4 had excellent printability. Furthermore, since the residual solvent is only derived from the adhesive, it has become clear that it is suitable for packaging materials such as beverages where residual solvent is avoided as much as possible. On the other hand, Comparative Examples 1 and 3 could not be printed because they did not contain a laser colorant. In addition, in Comparative Example 2, the laser colorant contained titanium oxide, so the entire film was white, and the amount of residual solvent was 2 mg in Example 1, but 5 mg in Comparative Example 2, and the printing ink was The solvent derived from the type of laser coloring agent remained. In Comparative Example 4, printing was not possible because the printing surface was on the front side.

The laminate for laser printing of the present invention has been specifically explained above using the embodiments and examples, but the laminate for laser printing of the present invention is limited to the description of these embodiments and examples. Many modifications can be made without departing from the spirit of the invention.

1 Laser coloring layer 10 Laser coloring layer laminate 11 Laser coloring layer 12 First polyolefin resin layer (outer layer)
13 Second polyolefin resin layer (inner layer)
20, 30, 40 Laser printing laminate 21, 31, 41 Base layer 22, 32, 42 Sealant layer

Claims (4)

a light shielding layer;
Equipped with a laser coloring layer containing a polyolefin resin and a laser coloring agent,
A laminate for laser printing, wherein the laser coloring agent includes a polymeric substance, mica or a mica-like substance, a metal sulfide, and one or more types of organic non-black pigments. The laminate for laser printing according to claim 1, further comprising a layer made of polyolefin resin, superimposed on the laser coloring layer. The amount of addition of the laser coloring agent is 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 types. The laminate for laser printing according to claim 1, containing 0.01 to 9.9% by mass of an organic non-black pigment. 1. 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. 3. The laminate for laser printing according to any one of 3 .

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