JPH0623918A - Multilayer boxboard product - Google Patents

Abstract

PURPOSE: To provide a multilayered thick paper product usable even in aseptic packing and made usable as liquid packing thick paper proper to the recycle of a raw material in a usual pulper by constituting the product by including a plastic layer having mechanical strength capable of being substantially integrally removed in pulping treatment. CONSTITUTION: A plurality of plastic layers are formed on the undersurface of the main layer of a thick paper product, that is, on the surface coming into contact with an article to be packed. These plastic layers starting from the thick paper layer 1 are an LDPE layer 5, the bonding layer 6 comprising, for example, modified polyethylene formed on the surface thereof, the barrier layer 7 of ethylene vinyl alcohol or EVOH formed on the surface thereof, the second bonding layer 8 similar to the first bonding layer comprising modified polyethylene formed on the surface thereof and the layer 9 like LDPE finally formed on the surface of the layer 8 to be brought into contact with the product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer cardboard product used as a packaging material having an upper surface facing away from the object to be packaged and a lower surface in contact with the product to be packaged.

[0002]

2. Description of the Prior Art Packaging cardboard must meet several requirements that are specifically defined by the items to be packaged. These requirements are in some cases very high, especially when it comes to cardboard for liquid packaging. Liquid packaging cardboard typically has a main layer of cardboard material and the disinfecting effect of a printable, liquid-tight, heat-sealable package formed on the surface facing away from the packaged item. And a plurality of plastic layers, such as LDPE layers, which are generally formed on the surface which is to be contacted with the packaged object to form a liquid-tight and gas-tight lower surface, and for example those layers And a barrier layer such as EVOH or aluminum disposed between the layers. The purpose of the barrier layer is to make the cardboard product oxygen impermeable, which is required for aseptic packaging. The cardboard layers typically contained in this type of liquid packaging cardboard are strongly adhered by a neutral adhesive, such as a ketene duplex adhesive, which results in a raw edge penetration value (at a temperature of 23 ° C. and relative humidity). Of 65%, the degree of sizing is relatively low, as indicated by the amount of gram of 1% lactic acid that penetrates into the cardboard per meter of raw edge of the cardboard in 24 hours) and therefore the cardboard layer itself is wet. It is called strong cardboard, and as it is, it is unsuitable for ordinary refibring, that is, pulping of waste paper. Furthermore, liquid-wrapped cardboards are coated on both sides with plastic, so that they form a product which is hardly wetted and also not decomposed. Therefore,
Products of this type are not suitable for recycling because they cannot be decomposed at all in the usual pulping process.

[0003]

It is an object of the present invention to be suitable for use as a liquid packaging cardboard which can be used even for aseptic packaging and which is suitable for recycling raw materials in conventional pulpers. Is to provide.

[0004]

According to a first embodiment, the object of the present invention is to measure for 24 hours with 40% or more groundwood pulp, the raw edge penetration value of the layer of which is 1% lactic acid. In the range of 0.5 to 2.5 g / m, a main layer of a cardboard material, and an inorganic coating layer formed on the upper surface of the main layer,
Inorganic coating At least one lacquer layer formed on the surface of the coating layer and a plastic layer formed on the lower surface of the main layer, the layer being pulping carried out in connection with the recycling of the product. And a plastic layer that is mechanically strong such that it can be removed essentially as a unit during processing.

According to a second embodiment of the present invention, a cardboard product contains 40% or more groundwood pulp and the layer has a raw edge penetration value of 0.5% measured with 1% lactic acid for 24 hours. ~
A main layer of a cardboard material in the range of 2.5 g / m, an inorganic coating layer formed on the upper surface of the main layer, a printing ink layer formed on the surface of the inorganic coating layer, and a printing ink layer At least one lacquer layer formed on the surface of and a plastic layer formed on the lower surface of the main layer,
This layer comprises a plastic layer that is of mechanical strength such that it can be removed essentially as a unit in the pulping process carried out in connection with the recycling of the product.

According to a third embodiment of the present invention, a cardboard product contains 40% or more groundwood pulp, the layer having a raw edge penetration value of 0.5% measured at 24 hours with 1% lactic acid. ~
A main layer of cardboard material in the range of 2.5 g / m, an inorganic coating layer formed on the upper surface of the main layer, a lacquer layer formed on the surface of the inorganic coating layer, and a surface of the lacquer layer A printing ink layer formed on the surface of the printing ink layer, at least one lacquer layer formed on the surface of the printing ink layer, and a plastic layer formed on the surface of the lower surface side of the main layer, which layer is for recycling the product. And a plastic layer that is mechanically strong such that it can be removed essentially as a unit during the associated pulping process.

The product according to the invention solves the problems associated with product degradation in the pulping process on the basis of three basic ideas. First, the water-repellent, heat-sealable, antiseptic-hardening layer that forms the outer surface of the product is not formed by the plastic surface layer and the inorganic coating on the cardboard surface and at least one lacquer applied to the surface of the inorganic coating Formed by layers. It is preferred that the inorganic coating therefore also function as an expectation for the printing ink layer. In the pulping process, the one or more lacquer layers and the mineral layer are decomposed into small pieces that do not interfere with the processing of pulp produced by pulping, as in cardboard making machines.

According to the second basic idea of the cardboard product of the present invention, the plastic layer formed on the surface of the product which comes into contact with the liquid to be packaged is not decomposed in the pulping treatment,
Made stronger enough to move away from the cardboard that is essentially pulped together. It is therefore possible to remove the plastic layer from the pulper, which has no possibility of affecting the quality of the pulp produced. The plastic waste generated can be easily recovered from the pulper and used, for example, in the manufacture of products typically made from plastic waste.

Third, the disassembly of the cardboard itself should be at least 4
It contains 0% groundwood pulp, especially wood, and its raw edge penetration value is sufficiently high as measured by 1% lactic acid for 24 hours, i.e. in the range 0.5-2.5 g / m, preferably 1-
Guaranteed by using cardboard that is in the range of 2 g / m. The value of this raw edge permeation value is 1 m of the raw edge of cardboard when the temperature is 23 ° C and the relative humidity is 65%.
1 shows the gram amount of 1% lactic acid that penetrates into cardboard in 24 hours per hour. As a result, a product is manufactured in which the fibrous material is easily decomposed during fiberization, even though it is bonded so as to be water-repellent.

The multi-layer cardboard product of the present invention used as a liquid packaging cardboard will now be described in greater detail with reference to the accompanying drawings.

[0011]

EXAMPLE As shown in FIG. 1, the main part of this product is 200-450 depending mainly on the size of the package to be made.
It is formed by a cardboard layer 1 having a thickness of μm. The cardboard layer 1 must be sufficiently resistant to moisture and must also be easily decomposed in the pulping process, so that its raw edge penetration value is in the range 0.5 to 2.5 g / m, preferably It should be in the range of 1-2 g / m. This main cardboard is preferably made from pulp with a proportion of groundwood pulp of at least 40%, preferably 40-80%. It is therefore in particular a pulp produced by a wood treatment suitable for use as groundwood pulp. Suitable adhesives used to adjust the raw edge penetration values of cardboard to the desired range are resin and neutral adhesives, especially admixtures in suitable proportions used in combination. Commonly used adhesives for liquid packaging cardboard are neutral adhesives such as ketene dimers and alkylanhydrous amber. Here, by replacing at least a part of the neutral adhesive with the resin adhesive, the sizing degree of the pulp is reduced and the decomposition of the pulp during pulping is improved. As a result, the product decomposes in the pulping process but is sufficiently resistant to moisture.

According to the invention, the surface of the cardboard main layer 1 facing away from the product is provided with an inorganic coating, for example 10 to 20 g.
It is formed by changing the strength within the range of / mm ² . The inorganic coating is, for example, clay. The main purpose of the mineral coating is to provide the cardboard with a surface which is suitable for printing but which is easily decomposed in pulping where the cardboard layer 1 is exposed to moisture. When decomposed, this mineral coating does not form particles that would cause problems in subsequent pulp processing and its conversion into a product.

In the embodiment of FIG. 1, a printing ink layer 3 is formed on the surface of the inorganic coating 2. Naturally, the thickness and position of this printing ink will vary depending on the pattern to be printed, and a printing ink layer of this kind will have an inorganic coating 2
May not be found on all parts of the surface. The thickness of the printing ink layer is typically 2-4 g / m ² .

Two lacquer layers 4 are formed on the surface of the printing ink layer 3 in order to protect the cardboard product according to the invention from external moisture. In connection with the treatment of the cardboard products according to the invention, it is particularly important that these lacquer layers 4 are preferably formed simultaneously with the printing ink layer 3 or at least on the same machine. In other words, the lacquer layer 4 is formed using printing technology. In this case, relevant techniques include the use of gravure roll units and offset processing. With both of these treatments, one or more lacquer layers can be made to the desired thickness and they can be matched. The lacquer layer can therefore be made thicker than the other area parts of the package in the area part, for example the lower surface, where the external moisture of the package to be produced has the greatest stress, or more than one lacquer layer can be used. . The typical thickness of the lacquer layer varies from ² to 6 m ² . A lacquer that can be used is a vinyl-based lacquer and an alcohol / ester mixture such as ethanol / ethyl acetate is used as a diluent. Water dispersants of polymeric acrylates can be used particularly advantageously as lacquer layers. In terms of product recoverability, the lacquer layer 4 is decomposed into small pieces that do not cause problems in the subsequent pulping process and its conversion into a product in the conventional pulping process, and also protects the product sufficiently from external moisture. .

In the exemplary embodiment of FIG. 1, a plurality of plastic layers are formed on the underside of the main layer 1 of the cardboard product according to the invention, ie on the surface in contact with the item to be packaged. These plastic layers starting from cardboard layer 1 are LDPE layers 5,
A tie layer 6 formed on the surface thereof, such as modified polyethylene, a barrier layer 7 of ethyl vinyl alcohol or EVOH formed on the surface thereof, and a first tie layer such as modified polyethylene formed on the surface thereof. A second tie layer 8 similar to, and finally a layer 9 such as LDPE, which is formed on the surface of layer 8 and is in contact with the product. FIG. 1 shows an exemplary embodiment, in which these plastic layers formed on the product-side underside of the cardboard layer 1 and their number, the material and the order of the plastic layer components contained therein are in accordance with the invention. It is emphasized that changes can be made without departing from the product idea. The number, order and materials of layers involved is largely determined by the product to be packaged in the package. In connection with the object of the present invention, namely the recyclability of cardboard products,
The whole which constitutes these plastic layer components has such a mechanical strength that it remains essentially integral in the pulping process carried out with conventional pulpers and therefore can be removed substantially entirely in this process. Must be Thus, the plastic layer does not produce particles or other elements that would interfere with further processing of the pulp produced in the pulping process. Plastic waste can be used, for example, in the production of products commonly made from the plastic waste.

As mentioned above, in the exemplary embodiment of the drawing which is contacted with the item to be packaged, the plastic coating comprising layers 5, 6, 7, 8 and 9 is left as one in the pulping process. 26g / m ^{2 on} the inside of normal milk packaging cardboard
It is coated with polyethylene and does not meet this requirement. The preferred durable construction is such that this plastic layer has a normal LDPE coated polythene density, i.e.
It has been found to be achieved when the composition comprises at least one plastic layer component having a density greater than 925 g / m ³ . Such a component is, for example, HDPE (density 0.941 g / m ³ ), particularly preferred is ethylene vinyl alcohol or EVAL (density 1.19 g / m ³ ).
m ³ ). However, such plastics also have sufficient tensile properties, preferably greater than 100% (A
STM standard D-638 condition) is also required. It is therefore possible to produce coatings which remain integral in the pulping process even when the amount of coating is about 20 g / m ² .

The multi-layer cardboard product of the present invention has been described above with respect to only one exemplary embodiment, and some improvements do not depart from the basic idea of the invention and are also limited by the scope of the claims. It must be understood that what can be done without expanding.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a cross section of an exemplary embodiment of a cardboard product of the present invention.

[Explanation of symbols]

 1 Cardboard Layer 2 Inorganic Coating 3 Printing Ink Layer 4 Lacquer Layer 5,9 LDPE Layer 6,8 Bonding Layer 7 Barrier Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display part D21H 11/08

Claims (13)

[Claims] 1. A multi-layer cardboard product, which has an upper surface facing a side to be separated from a packaged object to be packaged and a lower surface which comes into contact with the packaged object and is used as a packaging material. And contains 40% or more groundwood pulp and the raw edge penetration value of the layer is 0.5-2.5 when measured with 1% lactic acid for 24 hours.
a main layer of a cardboard material in the range of g / m, an inorganic coating layer formed on the upper surface of the main layer, at least one lacquer layer formed on the surface of the inorganic coating layer, and A plastic layer formed on the lower surface, the plastic layer having such mechanical strength that it can be essentially removed as a unit in the pulping process carried out in connection with the recycling of the product. A multi-layer cardboard product characterized in that it is configured to include. 2. A multi-layer cardboard product having a top surface facing away from a packaged object to be packaged and a bottom surface in contact with the packaged object and used as a packaging material. And contains 40% or more groundwood pulp and the raw edge penetration value of the layer is 0.5-2.5 when measured with 1% lactic acid for 24 hours.
The main layer of cardboard material in the range of g / m, the inorganic coating layer formed on the upper surface of the main layer, the printing ink layer formed on the surface of the inorganic coating layer, and the surface of the printing ink layer A plastic layer formed on the underside surface of the main layer, the layer being essentially integral in the pulping process carried out in connection with the recycling of the product. A multi-layer cardboard product characterized by comprising a plastic layer having a mechanical strength that can be removed as a product. 3. A multi-layer cardboard product, which has a top surface facing away from an object to be packaged and a lower surface that contacts the object to be packaged, and is used as a packaging material. And contains 40% or more groundwood pulp and the raw edge penetration value of the layer is 0.5-2.5 when measured with 1% lactic acid for 24 hours.
The main layer of cardboard material in the range of g / m, the inorganic coating layer formed on the upper surface of the main layer, the printing ink layer formed on the surface of the inorganic coating layer, and the surface of the lacquer layer. A formed printing ink layer, at least one lacquer layer formed on the surface of the printing ink layer, and a plastic layer formed on the lower surface of the main layer, the layer being relevant for recycling of the product And a plastic layer having mechanical strength such that it can be removed as an integral part in the pulping treatment carried out as described above. 4. The cardboard product according to claim 1 or 2, characterized in that the groundwood pulp used to make the main layer is a pulp made from wood. . 5. The cardboard product according to claim 1 or 2, wherein the proportion of groundwood pulp in the cardboard of the main layer is 40 to 80%. 6. The cardboard product according to claim 1 or 2, wherein the raw edge penetration value of the main layer is in the range of 1 to 2 g / m when measured with 1% lactic acid for 24 hours. A multi-layer cardboard product characterized by that. 7. The cardboard product according to claim 1 or 2, wherein the adhesive used for adhering the main layer is a mixture of a neutral adhesive and a resin adhesive. Multi-layer cardboard products. 8. The cardboard product according to claim 1 or 2, wherein the weight of the inorganic coating layer is 10 to 20 g /
A multi-layer cardboard product characterized by being m ² . 9. Cardboard product according to claim 1 or 2, characterized in that the lacquer layer comprises a vinyl-based lacquer comprising an alcohol / ester mixture as diluent, preferably ethanol / ethylacetate. Multi-layer cardboard products. 10. A cardboard product as claimed in claim 1 or claim 2, characterized in that the lacquer layer comprises a water dispersant of polymeric acrylate. 11. The cardboard product according to claim 1 or 2, wherein the plastic layer is 0.925 g / m.
A multilayer cardboard product comprising at least one layer component having a density of ³ or greater. 12. The cardboard product according to claim 1, wherein the plastic layer has a tensile property of 100.
% Multi-layer cardboard product characterized by exceeding%. 13. The cardboard product according to claim 1, wherein the LDPE layer has a plastic layer in contact with the main layer, a first bonding layer on the surface of the LDPE layer, and an EVOH layer on the surface. And a second tie layer on its surface and an LDPE layer on its surface.