JPH11302995A - Impregnated paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide impregnated paper that reveals excellent performances according to the purposes, for example, physical properties relating to strength, rigidity, toughness, water repellency and the like and can be subjected to incineration treatment and recycle. SOLUTION: In the impregnated paper that is prepared by impregnating the body paper with a functional resin in the following step of making the body paper, at least >=80% of the thickness of the impregnated paper comprises the layer impregnated with the functional, resin component and the impregnation amount of the functional resin into the paper is in the range of 1-20% on the basis of the bone dry areal weight. In addition, this impregnated paper is treated with the impregnation mixture on one face or both of the front and back faces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to food and beverage products such as a paper box for snacks, a multi-pack outer paper box for collecting and packaging individually packaged products such as seasonings and beer cans, and small household electrical appliances. The present invention relates to a recyclable impregnated paper having excellent functions such as strength physical properties, rigidity, toughness, and water repellency and used as base paper for packaging materials such as an outer paper box and a paper box for a powder compact detergent container.

[0002]

2. Description of the Related Art In recent years, environmental problems have become more serious, containers and packaging materials have to be easily disposed of, and the demand for easy incineration, recyclability, or use of recycled materials has been increasing. It is a big social problem. There is a high social demand for the reduction and recycling of garbage, and even in the packaging container market, instead of metal cans, glass bottles, plastic bottles, and wooden boxes, paper that can be lightly incinerated and recycled as recycled paper In many cases, a container mainly composed of is used.

[0003] Compared with plastic containers and metal containers, paper containers have lower strength of the paper material itself and are more easily deformed. Therefore, when used in a heavy-weight packaging container or in an environment where a large pressure or load is applied, the required container strength may not be able to be maintained satisfactorily. However, paper containers that are easy to dispose and have excellent recyclability are required to have higher strength physical properties as the field of use expands.

Conventionally, when considering the packaging design of a paper container, a method for improving the strength of the paper used as the base paper of the packaging material has been proposed.
As a means, a physical concept method of using base paper having a large basis weight of paper and having a large paper thickness was considered. In addition, for example, virgin pulp having a large pulp fiber length, or a pulp fiber raw material having a large fiber length is selectively used as a component of paper, or a hard layer such as a clay coat layer is provided on a surface layer. Also, a method of selecting and using materials and a method of compounding were considered. Also,
Composite techniques of applying varnish to the surface of these papers made of paper or laminating a polymer such as polyethylene on the surface are also widely and generally used.

[0005] In the case of a paper material formed by laminating a polymer such as polyethylene on the surface of the base paper of a paper container, the stiffness of the laminated resin is increased.
Alternatively, it has been considered to increase the strength of the paper material by increasing the thickness of the laminate resin. However, the formulas that increase the amount of use of these materials and the formulas that compensate for the lack of strength due to compounding with other materials all require a large amount of materials, which inevitably leads to an increase in cost.

[0006] Base paper for use in packaging materials and the like in order to cope with environmental problems and resource saving is to use pulp fiber in order to minimize the amount of pulp fiber used within the range of required physical properties. Virgin pulp having a large length was selected or used, or base paper having a slightly larger basis weight was used because the base paper was made from recycled pulp made from recycled waste paper. Therefore, in the case of base paper using recycled pulp, base paper to which additives and impregnating agents are added in the paper making stage is made in order to compensate for various properties such as strength, which are necessarily reduced. In other words, the base paper as a packaging material corresponding to environmental problems and resource saving has secured the reduced strength of the paper itself by virgin pulp having a long fiber length, or an additive and an impregnating agent.

[0007] By using recycled paper pulp, a functional agent is added to the paper in order to compensate for the lost physical properties of the paper itself, such as the strength properties, or to impart further functional properties to the base paper using virgin pulp. A method of impregnation has been conventionally used. However, a functionally impregnated paper impregnated with a chemical generally has an impregnation formula in which a functional chemical is added at the papermaking stage. Therefore, in order to provide functions such as strength and water repellency required for the final form of the packaging container or the like, it is necessary to determine the specifications of the base paper material from the paper making stage. Therefore, the production of base paper with a specific specification requires mass production when considered from the general paper manufacturing process. It is.
With the conventional impregnation process at the papermaking stage, it is not easy to produce functional impregnated paper in a small lot. However, it is difficult to obtain the required paper, and inevitably the increase in material cost is a problem that occurs at the papermaking stage.

[0008] Also, a composite technique of coating a varnish on the surface of the paper thus formed or laminating a polymer such as polyethylene on the surface is widely and generally used. When used, for example, a method of laminating a polyethylene resin etc. on the paper surface after printing on the paper surface, and laminating the polyethylene resin etc. on the printing surface for water repellency and preventing damage to the printing surface is preferable in use. Therefore, in order to improve the strength of paper, the selective use of high-strength materials in the papermaking stage, the addition of impregnating materials in the papermaking stage, and the lamination of resin such as polyethylene are necessarily factors that increase costs. Was.

Therefore, in order to obtain a high-strength base paper while suppressing an increase in cost, a base paper which has been impregnated and has a reduced basis weight has been produced. In a general papermaking process, a process of laminating pulp in layers using a large amount of water is repeatedly performed. That is, a large amount of impregnating agent is required to obtain an impregnated paper in which the functional agent has been impregnated into the entire layer of the paper or 80% or more of the paper thickness.

The functions required of paper include strength,
Although there are water repellency and the like, for example, as a method of supplementing the strength of paper, a method of laminating a polymer such as polyethylene on the surface layer, coating the surface layer with a hard resin or impregnating the surface layer has been performed. Was. As a method of imparting water repellency, a method of coating or impregnating the surface layer of paper with rosin or a substance exhibiting water repellency has been used. That is, the conventional paper reforming technique is a reforming technique that acts on the surface layer of paper and a layer near the surface layer.

An impregnated paper in which the surface layer and the vicinity of the surface layer of the paper have been modified with a chemical agent exhibits strength physical properties and water repellency provided in the surface layer, but their functions remain in the modified portion of the paper surface layer. Show properties. For example, impregnated paper obtained by impregnating a surface layer with a modifier that modifies strength properties, when strength properties are evaluated by a bending strength test, a hard substance is impregnated near the surface layer of the paper. Therefore, it is recognized that the yield value indicating the rigidity and the bending strength is improved as compared with the base paper before the modification. However, the toughness and the yield angle, which indicates the difficulty in bending, are hardly improved, and may be reduced depending on the combination of the base paper and the impregnation modifier. In many cases, the paper was modified into so-called hard but brittle paper. Furthermore, for example, it is recognized that the impregnated paper obtained by impregnating the surface layer with a modifier for modifying water repellency has improved water repellency on the paper surface. When molded into a packaging container, the end face of the impregnated paper was not often exposed, and the exposed end face did not show any water repellency.

The present invention minimizes cost increase,
This makes it possible to more effectively improve the intended strength (rigidity, toughness). That is, as a secondary process after the paper is made, by impregnating with a resin solution, at least 80% or more of the thickness of the base paper is an impregnated portion containing the impregnated resin, and 1% by weight.
With the impregnated paper characterized by containing the resin component of 20% or less, not only the rigidity and toughness of the impregnated paper can be more effectively improved, but also the increase in manufacturing cost can be minimized. .

[0013]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of intensive studies by the inventors with the aim of solving the above-mentioned problems, and has been developed in the post-processing step of the formed base paper. In the impregnated paper in which the base resin is impregnated with the functional resin, at least 80% or more of the thickness of the impregnated paper is composed of the impregnated layer containing the functional resin component, and the impregnated amount of the functional resin component of the impregnated paper is By impregnating in the range of 1% to 20% of the absolute dry basis weight, strength physical properties, rigidity, toughness,
It is an object of the present invention to provide an impregnated paper having excellent functions according to purposes such as water repellency, and capable of being incinerated and recycled.

[0014]

The above object can be attained by the following means. That is, the invention according to claim 1 is directed to an impregnated paper in which a functional resin is impregnated into a base paper in a post-processing step of the formed base paper, wherein at least 80% or more of the thickness of the impregnated paper is the functional resin. It is characterized by comprising an impregnated layer containing the component, and the impregnated amount of the functional resin component of the impregnated paper is in the range of 1% to 20% of the absolute dry basis weight.

According to a second aspect of the present invention, in the impregnated paper according to the first aspect, the impregnated paper is provided with an impregnation formula on both sides of the paper.

According to a third aspect of the present invention, in the impregnated paper according to the first aspect, the impregnated paper is provided with an impregnation prescription on one side of the paper.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in more detail. The invention according to claim 1 is
In an impregnated paper in which a functional resin is impregnated into the base paper in a post-processing step of the formed base paper, at least 80% or more of the thickness of the impregnated paper comprises an impregnated layer containing a functional resin component, In addition, the impregnated amount of the functional resin component of the impregnated paper is in the range of 1% to 20% of the absolute dry basis weight.

The base paper constituting the impregnated paper of the present invention is a paperboard such as a ball, a kraft, or the like, or a paperboard mainly composed of recycled paper and kraft paper arranged on a surface layer, and having a thickness of 300 μm.
Although the above thick paperboard is preferably used, paper made of 100% virgin pulp, recycled paper made of waste paper, or paper made by laminating these papers in the paper making process is used. Any of the base papers can be used. The base paper constituting the impregnated paper of the present invention is not limited to the material and the configuration.

As the impregnating agent used in the impregnated paper of the present invention, a resin-based impregnating agent for strengthening the bonding between the pulp of the paper layer is preferably used. The impregnated resin in the impregnated paper acts by adhering to the joint between the pulp constituting the paper, thereby strengthening the joint portion where the pulp constituting the base paper of the impregnated paper is entangled, and exerts an external stress on the impregnated paper. The effect of preventing the displacement of the pulp when acted on is extremely large. As a result, the impregnated paper of the present invention has improved rigidity and toughness as compared with the base paper and the surface-modified paper.

Examples of the impregnated resin include acryl, acrylate, acrylonitrile, a copolymer of styrene and butadiene, and a patent application (reference number = P9609).
540) are preferably used. In the present invention, the material and composition of the impregnating agent disposed in the impregnated paper are not limited.

Further, a plurality of impregnating agents having different functions are mixed to use an impregnating agent exhibiting an interaction, or the impregnating step is divided into a plurality of stages, and the plurality of impregnating agents are arranged in the impregnated paper. It is also possible to obtain a multi-layer impregnated structure exhibiting multiple functions by the multi-layer structure. In the present invention, the present invention is not limited to the reaction modifying action of the impregnating agent in the impregnation process by using a plurality of impregnating agents, and the multilayer impregnating structure.

An impregnated paper in which the surface layer of the paper and the vicinity of the surface layer are modified with a chemical agent exhibits strength physical properties and water repellency provided in the surface layer, but their functions remain in the modified portion of the paper surface layer. Show properties. However, in the impregnated paper of the present invention, the intended modifying effect can be significantly enhanced by impregnating the chemical into 80% or more of the thickness of the entire paper. More preferably, by providing the impregnating agent in all layers of the paper, the functionality of the impregnating agent can be expressed in the entire region in the thickness direction of the impregnated paper to obtain a necessary and sufficient functional impregnated paper. .

The impregnated paper of the present invention is often molded and used as a packaging material in the form of a paper container, and is filled and packed in a container molded from the impregnated paper before being delivered to the consumer. In the distribution process up to this, container strength is particularly required.

In the conventional impregnated paper for ensuring the physical properties of the container, for example, impregnated paper in which a functional agent is impregnated near the surface of the base paper may be used. However, in containers using impregnated paper that has been impregnated near the surface layer of conventional paper, deformation can follow up to a certain external stress,
After being released from stress, it could be restored, but if an external stress exceeding the specified value was applied, the paper constituting the container would bend, and if further stress was applied, the function to protect the contents Loses. Further, the container released from the stress may have a damaged portion due to yielding (bending), resulting in poor appearance. Therefore, the present inventors further improved the strength performance of the container by imparting toughness in addition to rigidity to the physical properties of the container, and in order to obtain a container that is not easily damaged as a container, the thickness of the impregnated portion with respect to the thickness of the paper was reduced. Proposed impregnated paper with 80% or more

Further, the impregnated paper in the present invention has an impregnated layer containing at least 80% or more of the thickness containing the impregnated resin component, so that the impregnated resin component does not need to be excessively contained in the impregnated paper. It acts by adhering to the joints between the pulp composing the paper, strengthening the joints where the pulp composing the base paper of the impregnated paper is entangled, and displacing the pulp when external stress acts on the impregnated paper. It is sufficient that the resin is impregnated in a necessary and sufficient amount for exhibiting the effect of preventing the occurrence. Therefore, the present inventors have studied the minimum impregnated resin component for realizing the above-described functions, and as a result, the impregnated base paper, the resin component serving as the impregnating agent, and the impregnation process, As a result of earnest studies, it has been found that a necessary and sufficient modifying effect can be obtained with an impregnated amount of 1% to 20% of the basis weight of the impregnated paper as the added amount of the resin component. More preferably, if the addition amount of the impregnated resin component is 10% or less of the basis weight of the impregnated paper, the impregnated paper can be collected and recycled through a normal paper recycling line, depending on the selection of the impregnated resin component and the impregnation method. It is.

Further, in order to impart surface functions such as water repellency, water resistance and workability and / or strength,
It is also possible to use the impregnated paper of the present invention in a form in which a polymer such as polyethylene is laminated. As the polymer layer used by laminating on the surface of the impregnated paper, an olefin resin such as a polyethylene resin or a polypropylene resin, a polyester resin, a polyamide resin, a simple substance of a barrier resin such as an ethylene-vinyl alcohol copolymer, or A composite film combining these resins can also be used.

As a method for providing the polymer layer on the surface of the impregnated paper, any method of extrusion lamination, dry lamination, wet lamination or coating can be selected. The adhesive strength between the polymer layer and the impregnated paper is desirably such that the paper is peeled when peeled. Further, if the resin component contained in the impregnated paper and the resin layer provided on the surface of the impregnated paper are 10% or less of the basis weight of the impregnated paper, it can be collected and recycled through a normal recycling line. The present invention is not limited to the material and configuration of the polymer layer disposed on the surface of the impregnated paper, and the method of providing the polymer layer.

As described above, in the present invention, by providing the impregnated portion of the impregnated paper with a thickness of 80% or more, not only the rigidity but also the toughness is imparted, the strength performance is improved, and the addition amount of the impregnated resin component is increased. 1% of the basis weight of impregnated paper
By setting the content to 20% or less, the amount of the impregnated resin component used can be reduced as much as possible to provide a recyclable impregnated paper having higher rigidity and toughness than conventional impregnated paper.

According to a second aspect of the present invention, in the impregnated paper according to the first aspect, a functional resin is impregnated into the base paper in a post-processing step of the base paper. Is characterized in that both sides and near the surface of the impregnated paper are impregnated layers containing an impregnated resin.

When the functional resin is impregnated at the paper making stage, it is necessary to suppress the production cost by mass production. Therefore, by impregnating the base paper thus formed by a method such as coating, size pressing, dipping, etc., it is possible to cope with the production of a small lot, and it is possible to suppress an increase in the production cost. Any method can be selected as the method of impregnating the formed base paper, and any method can be selected as the method of impregnation depending on the type of the solution of the resin component to be impregnated and the base paper to be impregnated.

Base paper made by adding a water-repellent substance such as rosin in the paper making process, base paper coated with PVA, and other types of base paper having low permeability of water and organic solvent used by impregnated resin solvent In some cases, by impregnating the base paper from both sides and using a method such as size press, the impregnating agent can be efficiently impregnated into a layer ratio of 80% or more in the base paper, and the amount of impregnation can be controlled.

When an external stress is applied in the plane direction of the impregnated paper to cause the impregnated paper to bend and deform, one surface of the impregnated paper expands and the other surface compresses and deforms. Therefore, there are impregnated resin components which have extremely high tensile strength and compressive strength for the purpose of improving the strength physical properties. However, when these resin systems are selected and impregnation is performed, the thickness of the impregnated resin component is 80% from one side of the impregnation. Rather than making the part a hard layer and suppressing the deformation in the state of the base paper with the other side unmodified, by arranging hard layers on both sides of the impregnated paper, by suppressing the elongation deformation and the compression deformation at the same time Thus, deformation can be suppressed more efficiently.

Further, there is a resin in which the resin component of the impregnating agent expresses not only the strength physical properties of the impregnated paper but also the water repellency by compounding the agent to be impregnated to make it multifunctional. When these impregnating agents are used, the function for all layers of the paper and the function for the surface layer or the end face can be obtained by a single impregnation treatment. Therefore, by performing the impregnation process from both sides of the paper, a plurality of functions having different properties can be obtained in a single impregnation process.

According to a third aspect of the present invention, there is provided an impregnated paper according to claim 1, wherein the base paper is impregnated with a functional resin in a post-processing step of the formed base paper. By impregnating with the resin, 80% or more of the thickness of the paper from the one surface of the impregnated paper is composed of the impregnated layer containing the impregnated resin, and the one surface not impregnated is composed of the layer not containing the impregnated resin. .

By impregnating the formed base paper, it is possible to cope with the production of a small lot, and it is possible to suppress the increase in the production cost. In some cases, a polyethylene resin is laminated on one surface of the paper, or a paper is provided with a clay coat layer. By impregnating the base paper on which one side is surface-treated, the impregnated layer can be provided at 80% or more of the thickness of the paper by performing the impregnation treatment from the surface not subjected to the surface treatment. When the above-described base paper is subjected to the impregnation treatment, the impregnation treatment is performed only on one side. Therefore, the impregnation method is preferably used as a coating method, and more preferably, a fixed amount of a functional resin component such as gravure coating is used. The method can be arbitrarily selected depending on the solution type of the resin component to be impregnated and the base paper to be impregnated.

An embodiment of the present invention will be described below.

[0037]

<Example 1> As a base paper of impregnated paper, a basis weight of 40 was used.
Using kraft cardboard in which kraft paper was bonded to the surface of recycled paper obtained by recycling 0 g / m 2 of waste paper, an acrylic resin was used as a solution containing isopropyl alcohol as a solvent to obtain an impregnating liquid. After the base paper was impregnated from both sides of the base paper by the dipping method, ordinary drying treatment was immediately performed in an oven. The weight of the resin impregnated in the impregnated paper was 8 g / m2. In the impregnated paper, the acrylic resin was impregnated in all layers of the paper. The obtained impregnated paper was subjected to a bending strength test to obtain a yield value of 570 gf and a yield angle of 16.5 degrees. The yield value was 94 gf and the yield angle was 1.0 degrees compared to the base paper before impregnation. Each of them became larger, and the results obtained were both excellent in rigidity and toughness as compared with the base paper. In addition, the impregnated paper exhibited an excellent effect of water repellency on the paper surface. Further printing impregnated paper,
It was formed into a container through the steps of punching and sack sticking. The container obtained did not deform during distribution and consumption. The used containers could be put on a normal paper recycling line.

<Example 2> As the base paper of impregnated paper, basis weight 4
Using kraft cardboard in which kraft paper was bonded to the surface of recycled paper obtained by recycling 00 g / m2 waste paper, an acrylic resin was used as a solution containing isopropyl alcohol as a solvent to obtain an impregnating liquid. After the base paper was impregnated from both sides of the base paper by the dipping method, ordinary drying treatment was immediately performed in an oven. The weight of the resin impregnated in the impregnated paper is 30 g / m2
Met. Acrylic resin is impregnated in all layers of the paper in the impregnated paper. A bending strength test was performed on the strength of the obtained impregnated paper. As a result, a yield value of 827 gf and a yield angle of 19.1 degrees were obtained. The yield value was 353 gf and the yield angle was 3.7 degrees compared with the base paper before impregnation. Each becomes larger, rigidity,
Excellent results were obtained in both toughness. In addition, the impregnated paper exhibited an excellent effect of water repellency on the paper surface, and the water absorption from the end face was extremely small, so that an impregnated paper usable as a waterproof paper was obtained.

<Example 3> The basis weight of the impregnated paper was 5
Using a coated cardboard of 50 g / m 2, a polysilane-based resin was prepared as a solution using isopropyl alcohol as a solvent to obtain an impregnation liquid. After the base paper was impregnated by a gravure coating method from one side of the base paper that was not clay-coated, a normal drying treatment was immediately performed in an oven. The weight of the resin impregnated in the impregnated paper was 6 g / m2. In the impregnated paper, the 80% layer of the paper was impregnated with the polysilane resin from the impregnation side. When a bending strength test was performed on the strength of the obtained impregnated paper, a yield value of 760 gf and a yield angle of 22.3 degrees were obtained. Yield value is 1 compared to base paper before impregnation
05gf, the yield angle was increased by 3.5 degrees, and a result excellent in both rigidity and toughness as compared with the base paper was obtained. Further, the impregnated paper was formed into a container form through the steps of printing, punching, and sticking. The obtained container did not deform during distribution and consumption. The used containers could be put on a normal paper recycling line.

<Comparative Example 1> The basis weight of the impregnated paper was 4
Using kraft cardboard in which kraft paper was bonded to the surface of recycled paper obtained by recycling 00 g / m2 waste paper, an acrylic resin was used as a solution containing isopropyl alcohol as a solvent to obtain an impregnating liquid. After the base paper was impregnated from one side on the ball side of the base paper with a gravure coater, ordinary drying treatment was immediately performed in an oven. Weight of resin impregnated in impregnated paper is 8g
/ M2. The acrylic resin was impregnated in the impregnated paper in a layer having a thickness of 50% of the thickness of the paper. When a bending strength test was performed on the strength of the obtained impregnated paper, a yield value of 550 gf was obtained.
A yield angle of 15.0 degrees was obtained. Although the yield value was larger by 74 gf than the base paper before impregnation, the yield angle was smaller by 0.5 degrees. Compared with the base paper, the rigidity was excellent, but the toughness was poor. Also, the obtained impregnated paper showed an excellent effect on the water repellency of the paper surface on the ball side surface which is the impregnated surface,
No water repellency was observed on the opposite craft side.

<Comparative Example 2> The basis weight of impregnated paper was 5
Using a coated cardboard of 50 g / m 2, a polysilane-based resin was prepared as a solution using isopropyl alcohol as a solvent to obtain an impregnation liquid. After the base paper was impregnated by a gravure coating method from one side of the base paper that was not clay-coated, a normal drying treatment was immediately performed in an oven. The weight of the resin impregnated in the impregnated paper was 6 g / m2. In the impregnated paper, a 30% layer of the paper was impregnated with the polysilane-based resin from the impregnation side. When the bending strength test was performed on the strength of the obtained impregnated paper, a yield value of 730 gf and a yield angle of 17.1 ° were obtained. The yield value was 8 compared to the base paper before impregnation.
As a result, the yield increased by 5 gf, the yield angle decreased by 1.7 degrees, and the rigidity was superior to the base paper, but the toughness was inferior.

Table 1 shows the evaluation results of the impregnated papers obtained in the examples of the present invention.

[0043]

[Table 1]

[0044]

According to the present invention, in the impregnated paper in which the base resin is impregnated with the functional resin, at least 80% or more of the thickness of the impregnated paper consists of the impregnated layer containing the impregnated resin component. By selecting and impregnating a functional resin appropriately according to the purpose within the range of 1 to 20% of the absolute dry basis weight, excellent functions such as strength physical properties, rigidity, toughness, and water repellency are provided according to the purpose. And a recyclable impregnated paper can be provided.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsuko Harasawa 1-5-1, Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (72) Inventor Kentaro Yamawaki 1-1-5-1, Taito, Taito-ku, Tokyo Letterpress Printing Co., Ltd.

Claims (3)

[Claims] 1. An impregnated paper in which a functional resin is impregnated into a base paper in a post-processing step of the formed base paper, wherein at least 80% or more of the thickness of the impregnated paper contains a functional resin component. An impregnated paper comprising a layer, wherein the impregnated amount of the functional resin component of the impregnated paper is in the range of 1 to 20% of the absolute dry basis weight. 2. The impregnated paper according to claim 1, wherein the impregnated paper has an impregnation prescription applied to both sides of the paper. 3. The impregnated paper according to claim 1, wherein the impregnated paper has an impregnation prescription applied to one side of the paper.