JP2007136895A - Laminate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminate allowing easy and reliable peeling of a thermoplastic resin layer laminated on a paper layer, and its manufacturing method enabling processing through conventinal processes. <P>SOLUTION: The laminate is formed by arranging a peelable printed layer on the front or back surface of a paper layer and by laminating a thermoplastic resin layer on the peelable printed layer through extrusion coating, and has a peeling strength between the peelable printed layer and the thermoplastic resin layer of 5-60 gf/15 mm-width (180-degree peeling and the pulling rate of 50 mm/min). The manufacturing method is characterized by forming a peelable printed layer on the front or back surface of the paper layer through gravure with a peelable printing ink. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laminate that is widely used as a packaging material in which a thermoplastic resin is laminated in order to impart functionality to a paper layer, and a method for producing the same.

  A laminate in which a thermoplastic resin layer such as polyethylene is laminated on the front surface and / or back surface of a paper layer is widely used as a packaging material. For example, it is suitably used for applications requiring water resistance in liquid paper containers, cartons such as frozen food cartons, paper trays, paper cups and the like.

  As a method of laminating a thermoplastic resin layer such as polyethylene on a paper layer, so-called extrusion coating in which a thermoplastic resin is thermally melted and coated on the paper layer is widely performed.

  However, although the packaging material using the laminated body in which the conventional thermoplastic resin layers are laminated as described above is excellent in functionality such as water resistance, the paper layer and the thermoplastic resin layer strongly adhere to each other. Therefore, the paper layer and the thermoplastic resin layer cannot be easily peeled off to separate the paper and the plastic, and there is a problem that the paper layer is not suitable for recycling as a paper product after use. In particular, when used for oily contents, it is difficult to clean the inner surface, which hinders paper recycling.

  The present invention is a laminate capable of easily and reliably peeling a thermoplastic resin layer laminated with a paper layer in order to solve the above-described problems, and in a conventional manufacturing process. It aims at providing the manufacturing method of the laminated body which can be processed.

  According to a first aspect of the present invention for achieving the above object, a release printing layer is provided on the front or back surface of a paper layer, a thermoplastic resin layer is laminated on the release printing layer by extrusion coating, and the release printing layer is provided. And a thermoplastic resin layer having a peel strength of 5 to 60 gf / 15 mm width (180 degree peeling, tensile speed 50 mm / min).

  Further, the second invention provides a release printing layer on the front or back surface of the paper layer, a thermoplastic resin layer is laminated on the release print layer by extrusion coating, and the release print layer and the thermoplastic resin layer are laminated. Is a method for producing a laminate having a peel strength of 5 to 60 gf / 15 mm width (180 degree peeling, pulling speed 50 mm / min), wherein the release printing layer is peeled off from the front or back surface of the paper layer It is the manufacturing method of the laminated body characterized by providing by printing using the printing ink for printing, The said printing is gravure printing, It is characterized by the above-mentioned.

  According to the first aspect of the present invention, there is provided a laminate in which a release printing layer is provided on the front or back surface of a paper layer, and a thermoplastic resin layer is laminated on the release print layer by extrusion coating, By making the peel strength with the thermoplastic resin layer in the range of 5 to 60 gf / 15 mm width (180 degree peel, tensile speed 50 mm / min), it was used as a paper packaging material or the like and then laminated on the paper layer. The thermoplastic resin layer is easy to peel off, and the thermoplastic resin does not remain on the paper layer. Therefore, there is no contaminants left on the contents, and the paper layer can be used as an adaptable material for recycling. Even if it does not pollute the atmosphere, there is an excellent effect that it is possible to provide a packaging material that is friendly to resources and environmentally friendly.

  Further, according to the second invention, a laminate in which a release printing layer is provided by printing on the front or back surface of the paper layer by printing, and a thermoplastic resin layer is laminated on the release printing layer by extrusion coating. After being used as a packaging material made of body paper, etc., the thermoplastic resin layer laminated on the paper layer is easy to peel off. The peel strength between the paper layer and the thermoplastic resin layer is 5 to 60 gf / 15 mm width (180 degree peeling, tensile A laminate having a speed of 50 mm / min) can be obtained. In addition, since the printing is gravure printing, the coating amount is stable, the post-processing extrusion suitability is good, and the productivity is high.

  Hereinafter, the laminate of the present invention and the manufacturing method thereof will be described in detail based on specific embodiments.

  FIG. 1 is a schematic cross-sectional view showing an example of the configuration of an embodiment of a laminate according to the present invention. As shown in FIG. 1-a, the laminate 10A has a release printing layer on the surface of a paper layer 11. 12, and a thermoplastic resin layer 13 is laminated on the surface of the peeling print layer 12. As shown in FIG. 1B, the laminate 10 </ b> A has a pattern / display print layer on the surface of the paper layer 11. 14, a release printing layer 12 is provided thereon, and a thermoplastic resin layer 13 is further laminated on the surface of the release printing layer 12. As shown in FIG. Is a configuration in which a peeling printing layer 12 is provided on the back surface of the paper layer 11 and a thermoplastic resin layer 13 is laminated on the peeling printing layer 12. As the paper layer 11, paper including known paperboard such as paperboard such as coated balls and manila balls, milk carton base paper, cup base paper, kraft paper, and fine paper can be used. In order to set the peel strength with the plastic resin layer 13 in the range of 5 to 60 gf / 15 mm width (180 degree peel, tensile speed 50 mm / min), the smoothness of the surface of the paper layer 11 on which the peelable print layer 12 is provided is It needs to be in the range of 400 to 3000 seconds. The This smoothness measurement is described in J. TAPPI Paper Pulp Test Method No. Based on 5-74 “Testing method for smoothness and air permeability of paper and paperboard by air micrometer type tester”, it is performed by Oken type air permeability tester. When the smoothness is less than 400 seconds, even if the printing ink for peeling is printed, it is absorbed by the paper layer 11, the peeling strength exceeds 60 gf / 15 mm width, and peeling becomes difficult, and the smoothness is 3000 seconds. When the value exceeds 1, it becomes difficult to produce paper.

Further, in order to increase the smoothness of the surface of the paper layer 11, a surface processing agent such as talc, clay, aluminum hydroxide, titanium dioxide, precipitated calcium carbonate, which is generally widely used in paper surface processing, is applied. Paper is preferable, and the coating amount is preferably in the range of 5 to ²⁰ g / m2. When this coating amount is less than 5 g / m ² , the peel strength exceeds 60 gf / 15 mm width, making peeling difficult, and when the coating amount exceeds 20 g / m ² , the coat layer becomes weak and the peel strength is stable. do not do.

The release printing layer 12 is a release print mainly composed of a resin such as polyamide, polyester, urethane, rubber, acrylic, chlorinated PP, butyral, vinyl chloride-vinyl acetate copolymer, and nitrified cotton. Ink can be formed by printing. Moreover, you may add silicone etc. to said resin as needed. As printing, it can form by a well-known printing method. In particular, as the printing ink for peeling, an acrylic resin excellent in heat resistance and peelability, and an ink mainly composed of nitrified cotton are preferable. As a printing method, gravure printing is preferable because the coating amount is stable and the productivity is high. As the coating amount of the release print layer 12, but the range of 0.5 to 10 g / m ^2, preferably in the range from 1 to 5 g / m ^2. When the coating amount is less than 0.5 g / m ² , the peel strength exceeds 60 gf / 15 mm width, and peeling becomes difficult, and it is difficult to apply an amount exceeding 10 g / m ² by gravure printing.

  The thermoplastic resin layer 13 is composed of a low density polyethylene (hereinafter referred to as LDPE), a medium density polyethylene, a high density polyethylene, a linear (linear) low density polyethylene, and an ethylene-α / olefin copolymer polymerized using a metallocene catalyst. Polymer, polypropylene (hereinafter referred to as PP), ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methacrylic acid copolymer, ethylene- Polyolefin resins such as methyl methacrylate copolymer, ethylene-propylene copolymer, methyl pentene polymer, polybutene polymer, polyethylene or polypropylene are mixed with acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, Acid modification modified with unsaturated carboxylic acids such as itaconic acid Polyolefin resins, polyvinyl acetate resins, poly (meth) acrylic resin, polyvinyl chloride resin, a polyester resin, a resin layer such as nylon resin. Among them, low density polyethylene (hereinafter referred to as LDPE) and polypropylene (hereinafter referred to as PP) having a good balance between cost and processability can be suitably used. When the temperature of the contents is less than 100 ° C, it is preferable to use LDPE, and when the temperature of the contents is in the range of 100 to 160 ° C, it is preferable to use PP.

  In the laminate 10 of the present invention, the peel strength of the release printing layer 12 and the thermoplastic resin layer 13 provided on the paper layer 11 is in the range of 5 to 60 gf / 15 mm width (180 degree peel, tensile speed 50 mm / min). The paper layer 11 provided with the peeling printing layer 12 and the thermoplastic resin layer 13 can be peeled. When this peel strength exceeds 60 gf / 15 mm width, it becomes extremely difficult to peel the thermoplastic resin layer 13 from the paper layer 11 provided with the release printing layer 12, and when it is less than 5 gf / 15 mm width, it easily peels off. It becomes difficult to process into other products. Therefore, by making the peel strength in the range of 5 to 60 gf / 15 mm width, it can be used for various products such as packaging materials, and when used, the paper layer provided with the peelable print layer 12 easily after use. 11, the thermoplastic resin layer 13 can be peeled off to separate paper and plastic, which can be reused.

  About the measuring method of this peeling strength, 100 mm is cut out by a 15 mm width | variety body. The paper and film of 60 mm are peeled off from one of the cut outs and chucked on both chucks of the tensile tester. The distance between chucks is 100 mm. The unpeeled portion is peeled in the 180 degree direction at a pulling speed of 50 mm / min, and the maximum load is defined as the peel strength.

  The laminate 10 in which the peeling strength between the peeling printing layer 12 and the thermoplastic resin layer 13 provided on the paper layer 11 as described above is in the range of 5 to 60 gf / 15 mm width is the same as the processing conditions for printing and extrusion coating. It can be manufactured by setting.

  Below, the manufacturing method of the laminated body 10 of this invention is demonstrated. In this manufacturing method, first, a release printing layer 12 is provided on the front or back surface of paper. Usually, when a packaging material is used, a pattern or display is printed on the front surface, and a thermoplastic resin layer 13 is formed thereon. Is formed on the surface of the paper layer 11. As a printing method, it can be provided by known gravure printing, planographic printing, letterpress printing, screen printing, etc. Among them, the coating amount is stable, the extruding process suitability for post-processing is good, and the productivity is high. Gravure printing is preferred because it is high.

  Next, a thermoplastic resin layer 13 is provided on the surface of the release printing layer 12 in the extrusion coating process. The extrusion coating can be processed by a known method. When LDPE having a melting point of 105 to 115 ° C. is used as the resin for forming the thermoplastic resin layer 13, the extrusion temperature is set to 320 ° C. or more as processing conditions for extrusion coating. At this time, the line speed is set in a range of 80 to 200 m / min. Usually, the paper layer 11 is subjected to corona treatment. As a condition for this corona treatment, the output is set in the range of 1 to 10 kW.

  Further, PP having a melting point of 130 to 165 ° C. is used as the resin for forming the thermoplastic resin layer 13, the extrusion temperature is set to 280 ° C. or more as the processing conditions for the extrusion coating, and the line speed is set to 80 to 200 m / min. Set to the range of and process. Usually, the paper layer 11 is subjected to corona treatment. As conditions for this corona treatment, a range of output 1 to 10 kW is set.

  Here, the setting conditions have been described with LDPE and PP as the thermoplastic resin, but the release printing layer 12 and the thermoplastic resin layer provided on the paper layer 11 by appropriately setting the processing conditions for other resins as well. A laminate 10A having a peel strength of 13 in the range of 5 to 60 gf / 15 mm width can be obtained.

  Using the laminate 10A thus manufactured, post-processing can be performed to produce a product such as a packaging container. In these products, the thermoplastic resin layer can be easily peeled off after use, that is, the plastic and paper can be separated, and the paper portion can be reused.

  Next, the laminate of the present invention and the production method thereof will be described in more detail with specific examples.

<Example 1>
First, an acrylic resin is a main component on the surface of a paperboard (new ultra H; manufactured by Nihon Daishowa Paperboard Co., Ltd.) having a basis weight of 320 g / m ² that is the paper layer 11, that is, the coated surface (smoothness: 700 seconds). The printing layer 12 for peeling is printed by gravure printing using a solid printing plate having a plate depth of 30 μm using a printing ink for peeling (acrylic resin: solvent (MEK / ethyl acetate / IPA) = 30: 70). Was provided. The coating amount was 3 g / m ² . Next, a low-density polyethylene resin (trade name LC520; manufactured by Nippon Polyethylene Co., Ltd., melting temperature = 111 ° C.) is extruded from a die of an extruder, and a thermoplastic resin layer having a thickness of 60 μm is formed on the release printing layer 12. 13 was formed. As processing conditions at this time, the line speed was set to 80 m / min. The paper layer 11 was previously subjected to corona treatment at 4.5 KW. In this way, a laminated body 10A was produced.

  It was 15.5gf / 15mm width as a result of measuring the peeling strength of 10 A of laminated bodies processed on said conditions.

  Next, the laminated body 10A manufactured as described above is punched into a blank having a predetermined shape, and the blank is formed into a tray shape having dimensions of 250 mm × 180 mm × 20 mm (depth) by a deep drawing molding machine. A squeezed paper tray A was produced.

  After actually using this deep-drawn paper tray A, the thermoplastic resin layer 13 could be easily peeled off from the release printing layer 12 of the paper layer 11, and paper and plastic could be separated.

<Example 2>
First, as in Example 1, the surface of the paper layer 11 having a basis weight of 320 g / m ² (NEW Ultra H; manufactured by Nihon Daishowa Paperboard Co., Ltd.), that is, the coated surface (smoothness: 700 seconds) In addition, a pattern and display printing layer 14 was provided by gravure printing. Next, gravure printing using a solid printing plate having a plate depth of 30 μm using a printing ink for peeling mainly composed of acrylic resin (acrylic resin: solvent (MEK / ethyl acetate / IPA) = 30: 70) in the same step. Was printed and dried to provide a release printing layer 12. The coating amount was 3 g / m ² . Next, a low-density polyethylene resin (trade name LC520; manufactured by Nippon Polyethylene Co., Ltd., melting temperature = 111 ° C.) is extruded from a die of an extruder, and a thermoplastic resin layer having a thickness of 60 μm is formed on the release printing layer 12. 13 was formed. As processing conditions at this time, the line speed was set to 80 m / min. The paper layer 11 was previously subjected to corona treatment at 4.5 KW. In this way, a laminate 10B was produced.

  It was 13.8 gf / 15mm width as a result of measuring the peeling strength of the laminated body 10B processed on said conditions.

  Next, the laminate 10B manufactured as described above is punched into a blank having a predetermined shape, and the blank is formed into a tray shape having a size of 250 mm × 180 mm × 20 mm (depth) by a deep drawing machine. A squeezed paper tray B was produced.

  After actually using this deeply drawn paper tray B, the thermoplastic resin layer 13 could be easily peeled off from the release printing layer 12 of the paper layer 11, and the paper and the plastic could be separated.

<Example 3>
First, on the surface of a paperboard 11 having a basis weight of 320 g / m ² (Hyperl; manufactured by Mitsubishi Paper Industries Co., Ltd.), that is, a coated surface (smoothness: 700 seconds), for peeling mainly comprising an acrylic resin. Printing was performed by gravure printing using a solid plate having a plate depth of 30 μm using a printing ink (acrylic resin: solvent (MEK / ethyl acetate / IPA) = 30: 70), and the peeling printing layer 12 was provided. The coating amount was 3 g / m ² . Next, a polypropylene resin (trade name: Prime Polymer F109V; manufactured by Nippon Polyethylene Co., Ltd., melting temperature = 111 ° C.) is extruded from a die of an extruder, and a thermoplastic resin layer having a thickness of 60 μm is formed on the release printing layer 12. 13 was formed. As processing conditions at this time, the line speed was set to 80 m / min. The paper layer 11 was previously subjected to corona treatment at 4.5 KW and ozone treatment at 12 gN / m. In this way, a laminate 10A ′ was produced.

  It was 10.5 gf / 15mm width as a result of measuring the peeling strength of laminated body 10A 'processed on said conditions.

  Next, the laminate 10A ′ manufactured as described above is punched into a blank having a predetermined shape, and the blank is molded into a tray shape having a size of 250 mm × 180 mm × 20 mm (depth) by a deep drawing machine. Deep drawn paper tray C was manufactured.

  After actually using this deeply drawn paper tray C, the thermoplastic resin layer 13 could be easily peeled off from the release printing layer 12 of the paper layer 11, and the paper and plastic could be separated.

<Comparative Example 1>
A laminate 10D was produced in which the thermoplastic resin layer 13 was provided directly under the same processing conditions using the same material as in Example 1 without providing the release printing layer 12 on the paper layer 11 as in Example 1.

  As a result of measuring the peel strength of the laminate 10D processed under the above conditions, the paper layer 11 and the thermoplastic resin layer 13 were bonded, and the paper layer 11 and the thermoplastic resin layer 13 were not peeled but peeled off.

  Next, the laminated body 10D manufactured as described above is punched into a blank having a predetermined shape, and the blank is formed into a tray shape having a size of 250 mm × 180 mm × 20 mm (depth) by a deep drawing machine. A squeezed paper tray D was produced.

  After actually using this deeply drawn paper tray D, the thermoplastic resin layer 13 could not be peeled from the paper layer 11, and the paper and plastic could not be separated.

<Comparative example 2>
A laminate 10E in which the thermoplastic resin layer 13 was provided directly under the same processing conditions using the same material as in Example 3 without providing the release printing layer 12 on the same paper layer 11 as in Example 3 was produced.

  As a result of measuring the peel strength of the laminate 10E processed under the above conditions, the paper layer 11 and the thermoplastic resin layer 13 were bonded, and the paper layer 11 and the thermoplastic resin layer 13 were not peeled but peeled off.

  Next, the laminate 10E manufactured as described above is punched into a blank having a predetermined shape, and the blank is molded into a tray shape having a size of 250 mm × 180 mm × 20 mm (depth) by a deep drawing machine. A squeezed paper tray E was produced.

  After actually using this deep-drawn paper tray E, the thermoplastic resin layer 13 could not be peeled from the paper layer 11, and the paper and plastic could not be separated.

  The laminate of the present invention can be widely used as a material for packaging containers and the like. Specific examples include paper trays and cartons.

It is a section explanatory view showing an example of composition of a layered product of the present invention. It is sectional explanatory drawing which shows the structure of the conventional laminated body.

Explanation of symbols

10 Laminate (present invention)
10A Laminate (Example of the present invention)
10A ′ laminate (Example of the present invention)
10B Laminate (Example of the present invention)
10C laminate (Example of the present invention)
10D laminate (comparative example)
10E laminate (comparative example)
A, B, C Deep drawn paper tray (Embodiment of the present invention)
D, E Deep-drawn paper tray (comparative example)
11 Paper Layer 12 Peeling Print Layer 13 Thermoplastic Resin Layer 14 Picture / Display Print Layer

Claims (3)

A release printing layer is provided on the front or back surface of the paper layer, a thermoplastic resin layer is laminated on the release printing layer by extrusion coating, and the peeling strength between the release printing layer and the thermoplastic resin layer is 5 to 60 gf. / 15 mm width (180 degree peeling, tensile speed 50 mm / min). A release printing layer is provided on the front or back surface of the paper layer, and a thermoplastic resin layer is laminated on the release print layer by extrusion coating. The peel strength between the release print layer and the thermoplastic resin layer is 5 to 60 gf. / 15 mm width (180 degree peeling, tensile speed 50 mm / min) manufacturing method of a laminate, wherein the release printing layer is provided by printing using a release printing ink Manufacturing method. The method for producing a laminate according to claim 2, wherein the release printing layer is provided by gravure printing using a release printing ink.

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