JP6260265B2 - Resin laminate capable of laser marking and method for producing the same - Google Patents

Description

  The present invention relates to a resin laminate that can be marked by laser light irradiation and a method for producing the same.

A laser marking method is known in which colored marking is performed on a resin film or the like by irradiating a laser beam. The laser marking method is a method in which a resin layer in which a laser marking agent that develops color upon irradiation with laser light is dispersed is used to irradiate the resin layer with laser light and draw a desired character or pattern on the layer ( Patent Document 1).
In the present invention, the layer in which the laser marking agent is dispersed in the resin is called a laser marking layer so that the laser marking method can be performed.

On the other hand, as a resin container for accommodating various articles such as foods, pharmaceuticals, and cosmetics, the wall portion (including not only the side wall portion but also the bottom portion) of the container is constituted by two or more resin laminates. Multi-layer resin containers are known.
For example, in the case of a three-layer structure, the multilayer resin container has an inner layer 100 for configuring the inner surface 100a of the container, and an outer layer 200 for configuring the outer surface 200a of the container, as shown in FIG. It has a middle layer 300 with the necessary functions located between them. Depending on the lamination method, an adhesive layer may be interposed between these layers, or the layers may be directly joined to each other.

JP 2005-144784 A

  The present inventors add the laser marking layer to the resin laminate constituting the multilayer resin container in order to apply the laser marking method for printing on the body of the multilayer resin container for containing foods and the like. It was investigated.

However, when a laser marking layer was actually added to the resin laminate, it was found that the following problems to be improved occurred.
The problem is that, for example, when a multilayer resin container including a laser marking layer is formed by blow molding, a laser marking layer is also included in the scrap material generated by molding burr or the like. The problem is that loss occurs.
As a technique for reducing the loss of mill ends, a technique is known in which a recycle layer is added to the resin laminate and the mill ends are reused as a material for the recycle layer. However, in the case where the end material includes a laser marking layer, if a recycling layer using such end material is provided, in addition to the laser marking layer, the laser marking agent has a low concentration in the recycled layer. As a result, it was found that the recycle layer also slightly develops color by laser irradiation, resulting in problems such as double blurring of the marking.
Such a problem is a problem that occurs not only when the multilayer resin container for food is used but also when a laser marking layer is provided on a general resin laminate.

  An object of the present invention is to add a laser marking layer in a conventional resin laminate to enable clear laser marking while suppressing loss of a laser marking agent.

  As a result of intensive studies to solve the above problems, the present inventors have made the laser marking layer added to the resin laminate itself a recycled layer, and the end material including the laser marking layer as a material for the laser marking layer again. It has been found that the above-mentioned object can be preferably achieved by using this and supplementing the layer with a decrease in the concentration of the laser marking agent due to the use of mill ends, and the present invention has been completed.

The present invention provides the following.
[1] A resin laminate capable of laser marking,
A laser marking layer in which a laser marking agent is dispersed in a resin is included as one layer.
The laser marking layer is a layer in which one or both of the end material of the following (I) and the end material of the following (II) containing a laser marking agent is used as a material, and a predetermined image Characterized in that the material is a layer supplemented with a laser marking agent so that quality laser marking is achieved,
Resin laminate capable of laser marking.
(I) End material produced from another resin laminate having the same laminate structure as the resin laminate.
(II) An edge generated from another resin laminate having a laser marking layer in which the same laser marking agent as the laser marking agent contained in the laser marking layer is dispersed, which has a different laminate structure from the resin laminate. Wood.
[2] The resin laminate according to [1], wherein the laser marking layer is a layer using the end material of (I) as a material.
[3] The resin laminate according to [1] or [2], wherein the resin laminate has a laminate structure of three or more layers, and the laser marking layer is located as an intermediate layer of the laminate structure.
[4] The above-mentioned [1] to [4], wherein the entire form of the resin laminate is a container, and the resin laminate constitutes a wall portion of the container, whereby the container is a multilayer resin container. [3] The resin laminate according to any one of [3].
[5] The resin laminate according to [4], wherein the multilayer resin container is formed by blow molding.
[6] The resin laminate according to the above [4] or [5], wherein the multilayer resin container is a flexible multilayer resin container for accommodating mayonnaise-like food.
[7] The layers constituting the wall portion of the multilayer resin container are an inner layer, a laser marking layer, an adhesive layer, an oxygen barrier resin layer, and an adhesive layer in order from the inner side to the outer side of the multilayer resin container. The resin laminate according to the above [6], which is an outer layer.
[8] The resin laminate is a multilayer resin product having a sheet shape, a sheet material sheet, or a multilayer resin product obtained by sheet molding using the material sheet. The resin laminate according to any one of [1] to [3].
[9] A method for producing a resin laminate capable of laser marking,
A laminating step of forming the resin laminate so that the laser marking agent is dispersed in the resin as a laser marking layer as one layer of lamination,
In the laminating step, as the material of the laser marking layer, one or both of the following end materials (i) and the following (ii) containing a laser marking agent is used, and a predetermined image is used. Replenishing the material with a laser marking agent so as to achieve quality laser marking to form the laser marking layer,
The manufacturing method.
(I) End material produced from another resin laminate having the same laminate structure as the resin laminate to be produced by the production method.
(Ii) Other resins having a laser marking layer in which the same laser marking agent as the laser marking agent contained in the laser marking layer is dispersed, which has a laminated structure different from the resin laminate to be produced by the production method End material generated from the laminate.
[10] The method according to [9], wherein the end material of (i) is used as a material for the laser marking layer.

Conventionally, when laser marking is performed on a multilayer resin product, a new resin material (virgin material) has been used for the resin base material of the laser marking layer.
On the other hand, in the present invention, it is found that even a multilayer resin product in which many kinds of resins are used in combination can be used as a resin base material of a laser marking layer by mixing resin materials of each layer. . Based on this knowledge, in the present invention, a laser in a multilayer resin product that is newly molded and processed from an end material including a laser marking layer (for example, an end material generated by the previous molding process in the molding process). It is conceived to be used as a material for the marking layer.

  By forming the laser marking layer again using the end material including the laser marking layer, for example, the end material that has conventionally been discarded because it includes the laser marking layer is re-used as a material in the processing process. This makes it possible to suppress the loss of the laser marking agent and the loss of the end material including the laser marking layer.

Further, by using the end material including the laser marking layer, the following effects can be obtained as compared with the case where a large amount of the laser marking agent is added and dispersed in the virgin material.
First, since the end material including the laser marking layer already contains the laser marking agent, the amount of the laser marking agent to be added (that is, supplemented) so that the concentration necessary for laser marking is increased. Less.
In addition, the laser marking agent is already dispersed in the laser marking layer in the end material, and the end material including such a laser marking layer is pulverized, melted, kneaded, and a new material for the laser marking layer. By doing so, the laser marking agent is sufficiently uniformly dispersed in the material, although at a low concentration. Therefore, in the present invention, a small amount of the laser marking agent is supplemented and kneaded into the material in which the laser marking agent has already been dispersed.
When a laser marking agent is added to a virgin material resin containing no laser marking agent and kneaded, the laser marking agent as fine particles may be aggregated. On the other hand, it was found that if the end material including the laser marking layer is used as the material of the laser marking layer, the diffusion of the laser marking agent is promoted as compared with the case where it is put into the virgin resin. This phenomenon is considered to be because the affinity between the resin base material and the laser marking agent is further increased by preliminarily dispersing the laser marking agent in the resin base material. Thereby, compared with the case where a large amount of laser marking agents are added to a virgin material, the kneading | mixing for dispersion can be completed in a short time. Moreover, the possibility that a region where no laser marking agent is present is lower.

FIG. 1 is a schematic diagram showing an example of the structure of the resin laminate of the present invention, and is also a schematic diagram for explaining the production method of the present invention. FIG. 2 is a cross-sectional view showing an example of a multilayer resin container formed by blow molding. Fig.2 (a) is sectional drawing which showed the whole shape of the container, FIG.2 (b) is the partial expanded sectional view which expanded the part X of the wall part shown to Fig.2 (a). FIG. 3 is a table using photographs showing the results of laser marking on the multilayer resin container formed in the example of the present invention. FIG. 4 is a partially enlarged photograph and a partially enlarged photograph showing a result of laser marking on the multilayer resin container formed in the example of the present invention. FIG. 5 is a schematic view for explaining a cross-sectional structure (laminated structure) of a wall portion of a conventional multilayer resin container.

Hereinafter, the resin laminate according to the present invention will be described in detail with reference to its production method.
FIG. 1 is a diagram showing an example of a cross-sectional structure of a resin laminate according to the present invention. As shown in the figure, the resin laminate A according to the present invention is a resin laminate capable of laser marking by having a laser marking layer M. FIG. 1 shows an example of stacking three layers (first layer 1, laser marking layer M, and second layer 2) for explanation, but the number of layers may be two or more. .
The laser marking layer M is a layer in which a laser marking agent P that develops color when irradiated with laser light L is dispersed in a resin base material Q. In FIG. 1, the laser marking agents (P, P1, P2) are represented by black circles for the sake of explanation. However, the laser marking agents are not only particles made of a single material but also various kinds of material particles. It may be a mixture of or a molecule or element dissolved in a solvent.
FIG. 1 shows a state in which laser marking is performed by irradiating a laser marking layer M with laser light L from a laser light source device S.
In the resin laminate of the present invention, as the material of the laser marking layer M, one or both of the end material of the following (I) and the end material of the following (II) containing the laser marking agent P1 are used, and It is important that the material is supplemented with a laser marking agent P2 so that laser marking with a predetermined image quality is achieved.
(I) As shown in FIG. 1, an end material A10 generated from another resin laminate having the same laminate structure as the resin laminate A.
(II) It arises from another resin laminate having a laser marking layer in which the same laser marking agent as the laser marking agent P contained in the laser marking layer M is dispersed, which has a laminated structure different from the resin laminate. End material (not shown).

Moreover, FIG. 1 is also a figure which illustrates roughly the manufacturing method of the said resin laminated body. As shown in the figure, the manufacturing method of the present invention includes a laminating step for forming the resin laminate A so as to include the laser marking layer M as one layer of laminating. In the laminating step, as the material of the laser marking layer M, the end material of the following (i) containing the laser marking agent and one or both of the end materials of the following (ii) are used, and a predetermined image is used. It is important to form the laser marking layer M by replenishing and dispersing the laser marking agent P2 in the material so that quality laser marking is achieved.
(I) As shown in FIG. 1, an end material A10 generated from another resin laminate having the same laminate structure as the resin laminate A to be produced by the production method. This end material is the same as the above-mentioned end material (I).
(Ii) a laser marking layer having a different laminated structure from the resin laminate A to be produced by the production method and in which the same laser marking agent as the laser marking agent P contained in the laser marking layer M is dispersed. The end material (not shown) produced from the other resin laminated body which has. This end material is the same as the end material of the above (II).

The end materials (I) and (II) are both end materials and include a laser marking layer. As illustrated in FIG. 1, the laser marking layer M1 of the end material A10 includes a resin base material. The laser marking agent P1 is sufficiently dispersed in Q1. However, since the end material includes layers other than the laser marking layer M1 (in the example of FIG. 1, the first layer 10 and the second layer 20 of the end material A10), the laser marking on the entire end material is performed. The concentration (content ratio) of the agent P1 is lower than the concentration of the laser marking agent P in the target laser marking layer M. Therefore, if the end material is used as it is as the material of the laser marking layer M, a dark and clear quality image as required for the appearance of the product cannot be obtained.
Therefore, in the present invention, the material consisting of the end materials of the above (I) and (II) is further supplemented with the laser marking agent P2, kneaded and dispersed, and the concentration of the laser marking agent with respect to the entire material is determined. The density is increased to obtain a predetermined image quality (drawing quality).

In laser marking, the image quality (also called print quality when the image content is text or numbers) is determined so that the person or identification device can preferably identify it, such as darkness, sharpness, or size. It is done.
The image quality judgment criteria obtained by laser marking include, for example, that a human being can visually recognize characters and images drawn, and that a predetermined image identification device can identify drawn characters and images. . These determination criteria may be appropriately determined according to the application.
For example, an image that is directly related to the appearance of a product (when a product name, a trademark, or the like is drawn on the body of a container) requires a deep and clear image quality. Further, when a management number or the like for the producer is drawn small in the corner on the back of the article, the required image quality may be such that the producer can read it. In addition, for an image intended for identification by an image identification device, such as a barcode or a matrix type two-dimensional code, the required image quality may be as long as the image identification device is legible.
The image quality as described above is the “predetermined image quality” referred to in the present invention, and as described above, is appropriately determined according to the demand for the use and quality.
When replenishing the material using the end material with a laser marking agent, the concentration of the laser marking agent in the laser marking layer is the concentration necessary to satisfy the image quality so that the image quality can be obtained. Thus, the replenishment amount of the laser marking agent may be determined.

As the laser marking agent, a material that develops color by irradiation of laser light on the resin laminate and can perform the laser marking method can be used. For example, antimony-doped tin oxide, antimony or a compound thereof, an associated basic dye precursor (2,2-bis {4- [6 ′-(cyclohexyl-N-methylamino) -3′-methylspiro [phthalide-3, 9′-xanthene] -2′-ylamino] phenyl} propane), phthalide dye precursors, fluorane dye precursors, spiropyran dye precursors, lactam dye precursors, and the like.
The laser marking agent is preferably in a form suitable for molding, such as pellets, particles, and paste, as a master batch (a resin material containing a laser marking agent at a predetermined concentration). In such a case, the concentration of the laser marking agent may be controlled by the ratio between the weight of the resin base material and the weight of the master batch.

Preferred laser light when using the above laser marking agent is laser light with a wavelength of 10.6 μm obtained by a carbon dioxide laser device, laser light with a wavelength of 1090 nm obtained by a fiber laser device, and laser with a wavelength of 1064 nm obtained by a YAG laser device. Examples include light, laser light having a wavelength of 532 nm obtained by an SHG laser device, and the like, and a laser marking agent to be used and light having a wavelength capable of developing it may be appropriately selected and combined. An example of a preferable combination includes a combination of an antimony compound and a laser beam having a wavelength of 1060 nm.
In order to perform laser marking, a known laser marking device configured using the laser device as a light source can be used.

The appropriate concentration of the laser marking agent in the entire material constituting the laser marking layer varies depending on the type of the laser marking agent, but is generally 0.001 to 1.0% by weight, and 0.005 to 0.00. 8% by weight is a more preferable ratio. What is necessary is just to replenish a laser marking agent with respect to the material using the said end material so that it may become such a density | concentration.
In the production of the resin laminate, the laminated structure (thickness of each layer, the components of each layer) is sufficiently controlled, so that the above-mentioned end material also has a sufficiently controlled laminated structure. The content ratio is known. Therefore, the concentration of the laser marking agent in the whole mill is also known, so that the amount of the laser marking agent to be replenished and the amount of the master batch (resin containing the laser marking agent) to be replenished can be known. .

The end material that can be used for the laser marking layer in the present invention eliminates the loss of the laser marking agent generated from the resin laminate itself and the loss of the resin of the end material in the manufacturing process of the above (I). End material is most preferred.
The “other resin laminate having the same laminate structure as the resin laminate” in the above (I) or (i) is, in the manufacturing process of the resin laminate A, as illustrated in FIG. When it is going to form the resin laminated body A, it is the resin laminated body which has the same laminated structure manufactured before the resin laminated body A as the same product.
That is, in the present invention, an aspect in which the end material obtained in the molding process of the resin laminate to be manufactured is fed back and used as the material of the laser marking layer in the molding process is most preferable. In addition, if there are a plurality of apparatuses and molding lines for producing a resin laminate having the same laminated structure, the end material obtained from each apparatus or molding line may be used as a material for the laser marking layer in each molding line. .

Moreover, in the present invention, an end material having a similar laminated structure can be used, such as the end material (II) or (ii). For example, the number of layers slightly different from the resin laminate while having the same laser marking layer, the composition of the specific layer is different from the resin laminate while having the same number of layers as the same laser marking layer, etc. There may be a similar resin laminate. Such a resin laminate is the “other resin laminate” referred to in the above (II). The end material obtained from such a resin laminate also has a well-controlled laminate structure, and can be used as a material for a laser marking layer in the present invention.
Whether or not the end material can be used as a material for the laser marking layer can be known from the material configuration of each layer. For example, a trial molding is performed to achieve laser marking with a predetermined image quality. It may be determined whether or not.
The end material (I) and the end material (II) may be mixed and used.

In the example of FIG. 1, the end material of the above (I) is used, and the laminated structure of the end material A10 is also the same as that of the resin laminate A (the first layer 10, the laser marking layer M1, the first layer). Two layers 20).
The laser marking layer M1 of the end material A10 may be a layer made of an end material obtained from another resin laminate produced earlier and supplemented with a laser marking agent. It may be a layer in which a material and a predetermined amount of a laser marking agent are mixed (the first molding layer without using an end material). The same applies to the laser marking layer in the “other resin laminate” referred to in (II) or (ii) above.

  The end material as used in the present invention refers to a laser marking layer such as a molding burr generated when molding a resin laminate, a fragment produced by cutting a sheet-like resin laminate, a pulverized product of a defective shape, etc. And a reusable resin laminate.

In the case of producing a multilayer resin container by blow molding, as a process for reusing the end material as a laser marking layer, for example, the end material is pulverized, melted, and a laser marking agent is added (supplemented) while kneading. And kneading until the laser marking agent is uniform. The kneaded material is put into a hopper tank for a laser marking layer of a multilayer blow bottle, and blow molded with a resin material of another layer through a parison as a multilayer resin container.
For the treatment for using the end material as the laser marking layer, a technique of using the end material as the recycled layer can be referred to.

  The thickness of the laser marking layer is not particularly limited, but is preferably about 20 to 200 μm and more preferably about 50 to 130 μm from the viewpoint of preferably applying the laser marking method and obtaining a dark and clear marking. .

Conventionally, the resin base material of the laser marking layer includes polyolefins such as polyethylene and polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polymethacrylate, polyacrylonitrile, polycarbonate and copolymers thereof, polyethylene terephthalate, poly Polyesters such as butylene terephthalate, polyamide, polyacetal and the like are used.
On the other hand, in the present invention, since the resin base material of the laser marking layer is a material obtained by mixing the whole end material, the composition differs depending on the laminated structure of the resin laminate used as the end material.

  The number of layers of the resin laminate may be two or more including a laser marking layer as one layer. For example, a layer of about 2 to 7 layers is useful. The number of layers varies depending on the application and product grade.

  The laser marking layer has three or more layers for reasons such as preventing the laser marking agent from contacting the contents inside the bottle and preventing the laser marking layer from being scraped by physical contact from the outside of the bottle. It is preferably positioned as an intermediate layer of the laminated structure. The position of the laser marking layer in the laminated structure may be appropriately determined in consideration of the arrival state of the laser light and the position of other functional layers.

  The thickness of each layer other than the laser marking layer in the resin laminate varies depending on the function of the layer (protective film, support layer, adhesive layer, oxygen barrier layer, etc.). For example, if it is a flexible film-like product or a flexible multilayer resin container, the thickness of each layer is approximately 5 to 400 μm, and the total thickness of the resin laminate is approximately It is about 400-1000 micrometers. These numerical values are merely examples, and the thickness of each layer and the total thickness of the resin laminate need only be in accordance with the product.

The resin material of the layer other than the laser marking layer is not particularly limited, but as the resin material of the layer other than the adhesive layer, polyolefin such as polyethylene and polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polymethacrylate , Polyacrylonitrile, polycarbonate and copolymers thereof, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamide, polyacetal and the like. Necessary additives may be appropriately added to each layer.
Examples of the resin material for the adhesive layer generally include graft-modified polyolefins such as polyethylene using carboxylic acids such as maleic acid, itaconic acid, fumaric acid or the like, anhydrides, amides, esters, and the like. Preferred examples include polyethylene graft-modified with maleic acid or maleic anhydride.
Since the resin laminate is a material that constitutes a laser marking layer by mixing its end materials, a layer made of a material that inhibits layer formation, a layer made of a material that inhibits laser marking, etc. are being laminated. It is preferable not to include. The same applies to other resin laminates that produce the end material (II).

  Although the whole form of the said resin laminated body is not specifically limited, A planar form and a three-dimensional form are mentioned, Moreover, the multilayer resin product which has flexibility, and the multilayer resin product which has rigidity are mentioned. As used herein, “multilayer” means two or more layers.

Examples of the planar product include a multilayer resin product having a sheet shape and a sheet material for sheet molding. Specific examples of the multilayer resin product having a sheet shape include various film products and panel products that can be laser-marked.
What is necessary is just to determine suitably the laminated structure and external shape of the material sheet | seat for sheet | seat shaping | molding according to the product which should be shape | molded.

As a three-dimensional product, there are various types such as a bag-shaped multilayer resin product formed using the film-shaped product, a multilayer resin product obtained by subjecting the material sheet to a sheet molding process, and blow molding. Examples include multilayer resin products obtained by a molding method. Similarly to the material sheet for sheet molding, a parison for blow molding is also included in the resin laminate of the present invention.
The multilayer resin product obtained by the sheet molding process may be any multilayer resin product obtained by a conventionally known sheet molding process, such as a tray, a blister pack (also referred to as a PTP package (Press Through Package)), or a portion container.
Examples of the multilayer resin product obtained by blow molding include multilayer resin containers.
A multilayer resin container formed by blow molding is a product in which the usefulness of the present invention is particularly remarkable. This is because blow molding is suitable as a method for molding a multilayer resin container, and due to the process of fastening the parison with a mold, an end material having the same laminated structure as the product is produced.

FIG. 2 is a cross-sectional view showing an example of a multilayer resin container formed by blow molding. As shown in the figure, the resin laminate of the present invention constitutes the wall portion of the multilayer resin container. The wall has a laminated structure with a total of 6 layers.
The multilayer resin container illustrated in FIG. 2 has a preferable laminated structure having flexibility and oxygen barrier properties for containing mayonnaise-like food, and the inner layer (first layer) is formed in order from the inside to the outside of the container. Layer) 1, laser marking layer M, adhesive layer 3, oxygen barrier resin layer 4, adhesive layer 5, and outer layer (second layer) 2. In the example of the figure, the total thickness is about 400 μm to 1000 μm.
In a general application, there is no limitation on the positional relationship between the laser marking layer M and the oxygen barrier resin layer 4, and either layer may be located on the outer side.

In the multilayer resin container illustrated in FIG. 2, the inner layer 1 and the outer layer 2 are both main resin layers that contribute to the container shape and mechanical properties. The resin constituting the main resin layer is preferably a polyolefin resin composition, such as blow molding process characteristics, contents characteristics, mechanical characteristics, heat sealability when sealing a container opening, cost, etc. From the aspect, a polyethylene resin composition is more preferable.
Examples of the resin constituting the oxygen barrier resin layer 4 include ethylene-vinyl alcohol copolymer (EVOH) or metaxylenediamine / nylon from the viewpoint of oxygen barrier properties and safety. Metaxylenediamine / nylon has a high melting point and many restrictions on multilayer extrusion with polyethylene, and EVOH is more preferable. A resin for preventing delamination may be added to EVOH.
Further, as the resin constituting the adhesive layers 3 and 5, as described above, polyolefin such as polyethylene is graft-modified using carboxylic acid such as maleic acid, itaconic acid or fumaric acid or its anhydride, amide or ester. Preferred examples include polyethylene graft-modified with maleic acid or maleic anhydride. The adhesive layer may also be provided between the inner layer 1 and the laser marking layer M.
When the end material of the above (I) is used, the resin base material of the laser marking layer is a mixture of resins constituting the inner layer 1, the outer layer 2, the oxygen barrier resin layer 4, and the adhesive layers 3 and 5. .

  The mayonnaise-like food is an emulsified dressing mainly referred to in the Japanese Agricultural Standard (JAS), and specific examples include mayonnaise, salad dressing, tartar sauce, and other semi-solid dressings. In addition, mayonnaise-like foods also include product groups and emulsification-type sauces similar to mayonnaise, which have similar properties but do not conform to the JAS standards.

Mayonnaise-like foods include a variety of product lineups, including low-calorie, low-calorie, bean oil, and cholesterol-lowering products in addition to orthodox mayonnaise, so containers (mayonnaise bottles) It is preferable to impart discriminability.
However, the surface of the conventional mayonnaise bottle is difficult to adhere to ink, and there is a problem that printing cannot be performed with ink on the surface of the bottle. Moreover, the conventional mayonnaise bottle is a multi-layer resin container as described above, and is manufactured by blow molding. In the conventional general blow molding, end materials are generated.
Such a mayonnaise bottle is constituted by the resin laminate of the present invention as shown in FIG. 2, and the end material obtained in the molding process itself is used as a material for the laser marking layer, so that the bottle body is clear. In addition, it is possible to provide images and characters that do not disappear even when rubbed, and the loss of the laser marking agent and the loss of the end material are suppressed.

Hereinafter, an example is given and the composition of the present invention is explained more concretely.
In this example, a mayonnaise bottle was actually formed as a multilayer resin container having the laminated structure shown in FIG. 2, and characters were experimentally drawn on the body of the bottle by laser marking to evaluate the image quality.

[Specifications of mayonnaise bottle]
The resin material which comprises each layer of the manufactured mayonnaise bottle is as follows.
Inner layer 1: Low density polyethylene (LDPE)
Laser marking layer M: described later Adhesive layer 3: Modified polyethylene Oxygen barrier resin layer 4: Ethylene-vinyl alcohol copolymer resin (EVOH)
Adhesive layer 5: modified polyethylene outer layer 2: LDPE
The average thickness of the side wall is about 700 μm.

[Configuration of laser marking layer]
The laser marking agent used in this example was an antimony-based laser marking agent, which was in the form of a masterbatch (pellet) using polyethylene as a resin base material.
First, as a material for the first laser marking layer without using the end material, the masterbatch was added to and kneaded with polyethylene (virgin material) as a resin base material of the laser marking layer. The mixing ratio (weight ratio) between the resin base material and the master batch of the layer at this time was a standard mixing ratio recommended by the laser marking agent manufacturer.
A mayonnaise bottle (first molded product) having the first laser marking layer was produced by blow molding.
The average thickness of the side wall portion is about 700 μm, and the average thickness of the laser marking layer (first time) is about 130 μm.
The first molded product was pulverized and used as an end material for the next molding.
Since the laminated structure of the end material is known, based on this, the ratio of the weight of the laser marking layer to the entire end material was calculated, and the ratio of the weight of the master batch to the entire end material was also calculated. Based on this calculation result, in order to achieve the standard weight ratio of the masterbatch, it was calculated how much masterbatch should be replenished to the end material.
When the milling material is kneaded, the resin base material of the laser marking layer in the next molded product will be a mixture of the materials of each layer, but the unit volume with the resin base material (virgin material) of the first laser marking layer The difference in hit weight is very small and can be ignored.
With the replenishment amount calculated in this way, the master batch is added to the milled material, kneaded, and supplied as a material for the laser marking layer in the second molding (the same molding process as the first molded product). A mayonnaise bottle (second molded product) according to the invention was obtained.
The thickness of the laser marking layer (second time) is 130 μm.
In the second molding, the [kneading time until the end material and the laser marking agent are sufficiently kneaded can be recognized] is the same as that in the first molding [the virgin material and the laser marking agent are It was about 90% of the kneading time until a state where it could be recognized that the kneading was sufficiently performed. From this, it has been confirmed that the end material including the laser marking layer and the laser marking agent can be sufficiently kneaded in a shorter time.
The laser marking layer of the second molded article includes a master batch at a standard mixing ratio. Hereinafter, this sample is referred to as a standard concentration sample.
In the second molding described above, in addition to the standard density sample, a sample (high density sample) in which the replenishment amount of the master batch was increased was prepared in order to confirm the image quality. In the high-concentration sample, the replenishment amount of the master batch was increased so that the laser marking layer contained twice as much laser marking agent as the standard concentration.
In this embodiment, the resin base material and the laser marking agent are mixed based on the respective weights of the resin base material and the master batch, but may be mixed based on the concentration of the laser marking agent. Moreover, you may confirm the density | concentration of a laser marking agent by analysis as needed.

[Evaluation of bottles]
When the mayonnaise bottle (second molded product) according to the present invention was compared with a conventional mayonnaise bottle having no laser marking layer, it was found to have the same transparency, mechanical strength and flexibility as the conventional product. .

[Laser marking device]
The apparatus used for laser marking is a pulse transmission fiber laser marker (3D control FAYb laser marker, model name LP-Z250, Yb fiber laser, output 25 W, oscillation wavelength 1060 nm) manufactured by Panasonic Device Sunx Co., Ltd.

[Laser marking]
Characters were printed on the container body of the second molded product (standard concentration sample and high concentration sample) produced above while changing the laser marking conditions as follows.
The character width (width of one character) was 15 mm, 18 mm, 20 mm, and 23 mm.
The coating interval (laser trajectory interval) was set to the smallest possible interval for each character width, as shown in the table of FIG.
The scanning speed of the laser marking device is 4000 mm / second.
Laser marking is performed with the bottle stationary. The conveyor speed in the table of FIG. 3 indicates the numerical value set by the laser marking device.
The laser marking device used in this embodiment has a control configuration in which the conveyor speed can be set as a parameter, and the printable time is calculated by setting the conveyor speed. When marking, the laser light is automatically adjusted within the calculated printable time. Therefore, if the conveyor speed is set fast, the printable time is shortened, so that the coating interval is automatically adjusted. When the coating interval is widened, the obtained image (printing) appears thin.
The results of printing under the above conditions are shown in a table using photographs in FIG.

[Evaluation of laser marking]
As shown in FIG. 3, it was confirmed that the character color becomes darker as the character width is smaller.
In addition, there was no difference in character density between the standard density sample and the high density sample. This is presumably because the portion where the laser beam was irradiated was sufficiently colored, so the appearance of the print did not change much between the standard concentration sample and the high concentration sample. .
In the control configuration of the laser marking device used in the present example, it was found that the color of characters becomes darker at 12.5 m / min than at 25 m / min.

[Optical microscope observation of laser marking]
Printing was performed on the standard concentration sample while changing the scanning speed of the laser marking device, and a part of the characters was enlarged and observed with an optical microscope. Moreover, the part was cut | disconnected and the cross section was expanded and observed.
The scanning speed is 500 mm / second, 2000 mm / second, and 4000 mm / second.
Each enlarged image is shown as a table using photographs in FIG.
As shown in FIG. 4A, it was observed that the spot irradiated with the laser beam (pulse) was colored in a dot shape. FIG. 4B is an enlarged photograph of the laser marking printing result at 4000 mm / sec. As shown in the figure, it can be seen that only the portion irradiated with the laser beam (pulse) is colored.
It can be seen that the number of color spots increases as the scan speed is reduced.
In the observation of the cross section, it was observed that color was developed only in the laser marking layer as the intermediate layer. Further, it was confirmed that the entire laminate was swollen at a scanning speed of 500 mm / sec.

As is clear from the above examples, if the laser marking layer is formed using the end material of the resin laminate containing the laser marking layer, the quality equivalent to the conventional multilayer resin container (mechanical strength, chemical resistance, appearance) Etc.) was found to be obtained.
Further, it was found that even a laser marking layer using an end material containing a laser marking agent can achieve laser marking with sufficiently high image quality only by replenishing a small amount of the laser marking agent.

[Repeated molding]
When the second standard concentration sample was further used as an end material, the master batch containing the laser marking agent was supplemented in the same manner as in the above example, and the cycle of creating the standard concentration sample as the material of the laser marking layer was repeated. The quality of the bottle and the image quality of the laser marking were the same as in the case of the second molded product. Thus, it has been found that it is possible to eliminate the loss of the end material and the laser marking agent generated in the resin molding process including the laser marking layer.

  The present invention can be used for any resin laminate including a laser marking layer regardless of whether it is a film-like or panel-like product or a container-like product. According to the present invention, while adding a laser marking layer in a resin laminate constituting a multilayer resin container, loss of a laser marking agent is suppressed and clear laser marking is possible.

A resin layered body of the present invention 1 first layer 2 second layer M laser marking layer P laser marking agent Q resin base material of laser marking layer S laser light source device L laser light A10 end material 10 first end material Layer 20 Second layer of end material M1 Laser marking layer of end material P1 Laser marking agent of end material Q1 Resin base material of laser marking layer of end material P2 Laser marking agent to be replenished

Claims (16)

A resin laminate capable of laser marking,
A laser marking layer in which a laser marking agent is dispersed in a resin is included as one layer.
The laser marking layer is a layer in which an end material generated from another resin laminate having a laser marking layer in which the same laser marking agent as the laser marking agent is dispersed is used as a material, and a predetermined image Ri layer der laser marking agent is replenished to the material as laser marking quality is achieved,
However, in the resin laminate, the composition of the resin base material of the laser marking layer, the composition of each material of all other layers other than the laser marking layer, and the other resin laminate that produced the end material The composition of the resin base material of the laser marking layer and the composition of each material of all the layers other than the laser marking layer shall be the same as each other,
Due to the fact that the laser marking layer of the resin laminate is a layer in which the end material generated from the other resin laminate is used as a material, the resin base material of the laser marking layer of the resin laminate is the above-mentioned All other layers other than the laser marking layer in the resin laminate including the resin base material of the laser marking layer of the other resin laminate and the materials of all the remaining layers of the other resin laminate Each material has a different composition,
Resin laminate capable of laser marking . The end material produced from the other resin laminate is an end material produced from the resin laminate produced prior to the resin laminate in the production process of the resin laminate,
Due to the end material, the resin base material of the laser marking layer of the resin laminate includes materials of all layers other than the laser marking layer of the resin laminate ,
The resin laminate according to claim 1.   The resin laminate according to claim 1 or 2, wherein the resin laminate has a laminate structure of three or more layers, and the laser marking layer is located as an intermediate layer of the laminate structure.   The whole form of the said resin laminated body is a container, The said resin laminated body comprises the wall part of this container, Thereby, this container is a multilayer resin container, The any one of Claims 1-3 The resin laminate according to Item 1.   The resin laminate according to claim 4, wherein the multilayer resin container is formed by blow molding.   The resin laminate according to claim 4 or 5, wherein the multilayer resin container is a flexible multilayer resin container for containing mayonnaise-like food.   The layers constituting the wall of the multilayer resin container are an inner layer, a laser marking layer, an adhesive layer, an oxygen barrier resin layer, an adhesive layer, and an outer layer in order from the inner side to the outer side of the multilayer resin container. The resin laminate according to claim 6.   The resin laminate is a multilayer resin product having a sheet shape, a sheet material for sheet molding, or a multilayer resin product obtained by sheet molding using the material sheet. The resin laminated body of any one of -3. A method for producing a resin laminate capable of laser marking,
A laminating step of forming the resin laminate so that the laser marking agent is dispersed in the resin as a laser marking layer as one layer of lamination,
In the laminating step, as a material of the laser marking layer, an end material generated from another resin laminate having a laser marking layer in which the same laser marking agent as the laser marking agent is dispersed is used, and a predetermined image is obtained. supplemented with the laser marking agent to the material as laser marking quality is achieved, and forming the laser marking layer,
The manufacturing method . In the manufacturing process for manufacturing the resin laminate by the manufacturing method, the end material generated from the resin laminate manufactured in the manufacturing process prior to the resin laminate to be manufactured is used as the resin laminate to be manufactured. The manufacturing method of Claim 9 used as a material of a laser marking layer . The manufacturing method of Claim 9 or 10 with which the resin laminated body which should be manufactured with the said manufacturing method has a laminated structure of three or more layers, and the said laser marking layer is located as an intermediate | middle layer of this laminated structure. The whole form of the resin laminate to be produced by the production method is a container, and the resin laminate constitutes a wall portion of the container, whereby the container is a multilayer resin container. The manufacturing method of any one of 9-11. The manufacturing method of Claim 12 whose molding method of the said multilayer resin container is blow molding. The manufacturing method according to claim 12 or 13, wherein the multilayer resin container is a flexible multilayer resin container for containing mayonnaise-like food. The layers constituting the wall of the multilayer resin container are an inner layer, a laser marking layer, an adhesive layer, an oxygen barrier resin layer, an adhesive layer, and an outer layer in order from the inner side to the outer side of the multilayer resin container. The manufacturing method of Claim 14 which exists. The resin laminate to be produced by the production method is a multilayer resin product having a sheet shape, a sheet material for sheet molding, or a multilayer resin product obtained by sheet molding using the material sheet The manufacturing method of any one of Claims 9-11 which exists.