JP2001151269A - Multipack paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide inexpensive multipack paper which has sufficient tearing strength even when used paper pulp is mixed greatly. SOLUTION: This relates to a multipack sheet for storing and packaging a plurality of identical containers collectively. The sheet has at least two layers, and the total layer excluding the outermost layer not contacting the containers in storing or packaging contains 30-25% of hemp pulp and 75-97% of used paper pulp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper sheet in which a number of containers such as juice cans for canned beer and soft drinks, small beverage cans for small bottle drinks and beverage bottles are arranged in parallel. The present invention relates to a multi-pack paper used for wrapping and stacking.

[0002]

2. Description of the Related Art Conventionally, in order to collectively sell the above-mentioned beverage cans and beverage bottles, the containers are arranged in one or two rows, wrapped with one sheet of paper, and a package formed by stacking and packaging is multi-layered. It is called a pack and is widely used.

[0003] This multi-pack is generally and widely used in a bottom-lock system in which a container is wrapped from above and sealed at the bottom with a lock. As a lock type, a push-in lock in which a male lock and a female lock are overlapped and pierced at a predetermined position to seal them, and a plug-in lock in which a hook portion is inserted and sealed are known.

[0004] These multi-packs are required to have high strength of the multi-pack paper in order to prevent breakage of the package during transportation and damage to beverage cans and beverage bottles. Paperboard having a high basis weight of 300 to 500 g / m ² using long fiber virgin pulp is generally used.

As a method for increasing the tear strength of paper, there is known a method using pulp having a long fiber content and a long average fiber length. Specifically, in the case of wood pulp, softwood pulp is better than hardwood pulp, and unbleached pulp is better than bleached pulp. . Further, non-wood pulp such as hemp pulp is superior in tear strength to wood pulp, but is expensive and inexpensive paperboard such as multi-pack paper is not profitable. In addition, since it is a long fiber, the dispersibility in water is extremely poor and the formation is deteriorated. Therefore, it is necessary to beat and use the Canadian standard freeness to 600 ml or less, preferably about 500 ml. In the case of paperboard, the effect of formation deterioration tends to be slightly mitigated because of papermaking, but the effect of poor formation may cause uneven coating on the surface, and hemp pulp has extremely high air permeability. When hemp pulp is used for the middle layer because of its good characteristics, the air permeability differs depending on the layer, so there is a drawback that delamination trouble occurs easily in the press part, and hemp pulp cannot be used. .

On the other hand, various improvements have also been made in the package system, and as shown in JP-A-10-338266, the strength is improved by adopting a top-lock system in which a container is wrapped from below and sealed at the top with a lock. A multi-pack sheet is disclosed that does not break the package during transportation even if the sheet is weak. However, even in this method, when used paper pulp is blended as a raw material pulp, sufficient strength cannot be obtained, and it cannot be completely handled.

On the other hand, as seen in general paperboard, the use of waste paper pulp is desired from the viewpoints of the environment and the recycling of multi-pack paper, but paper having a high tear strength is required. In the current multi-pack paper, waste paper pulp is not blended or waste paper pulp is blended low,
Increasing blending of waste paper pulp has not progressed. Therefore, there has been a demand for inexpensive multi-pack paper that has sufficient tear strength even when used paper is used.

[0008]

SUMMARY OF THE INVENTION In view of the above situation, the present inventors have conducted intensive studies on the strength required at the time of using the multipack and a method for increasing the strength at a low cost. Multi-pack paper made by using hemp pulp and waste paper pulp in combination is extremely excellent in strength conventionally required, especially in tear strength,
They have found that low-cost multi-pack paper can be provided, and have completed the present invention.

[0009] An object of the present invention is to have a sufficient tear strength even when a large amount of waste paper pulp having a significantly lower tear strength is added and mixed as compared with the current multi-pack paper, and the weight of the material to be packaged during transportation is improved. Another object is to provide a multi-pack paper in which the package is not damaged by rough handling.

[0010]

SUMMARY OF THE INVENTION The present invention relates to a sheet for use in a multipack in which a plurality of identical containers are collectively stored and packaged, and the sheet is composed of at least two layers and is stored and packaged. Hemp pulp is 3% to 25% and waste paper pulp is 75% in the entire layer except the outermost layer which does not contact the container.
% To 97% and a specific tear strength of 15 mN / g / m ² or more,
The hemp pulp used in the present invention has a Canadian standard freeness of 650 ml or more and 700 ml or less.

In the present invention, it is important that hemp pulp and waste paper pulp which have been slightly beaten in a layer other than the surface layer are blended. By using hemp pulp that has been mildly beaten, it can be uniformly dispersed in waste paper pulp and the tear strength is greatly improved, so that the usage ratio of waste paper pulp can be greatly increased. Further, the basis weight can be reduced by the effect of improving the tear strength and reducing the density of hemp pulp.

[0012] On the other hand, hemp pulp has a drawback that the formation is poor due to a large amount of long fibers, but it must be subjected to mild beating,
In addition, it is possible to improve the formation by using waste paper pulp with a short fiber length and a large amount of fine fibers, and it is possible to improve the tear strength not only by the effect of hemp pulp but also by the synergistic effect of the combination of both. Have.

Further, in terms of efficiency during papermaking, wastepaper pulp is generally liable to cause delamination in a press roll due to poor air permeability during press dewatering from a wire part. By blending, there is a feature that air permeability is improved, delamination can be eliminated, and papermaking efficiency of a paper machine is improved.

The hemp pulp used in the present invention includes, but is not particularly limited to, bast fibers such as hemp, flax, chomp, and kenaf (horse hemp), and leaf fibers such as manila hemp and sisal hemp. However, alkali cooked, sulfite cooked and kraft cooked Manila hemp pulp is preferable, and if fiber strength and fiber length which affect the tear strength of paper are taken into consideration, sulfite cooked Manila hemp pulp is preferable.

In the present invention, hemp pulp and waste paper pulp are blended, and the Canadian standard freeness of hemp pulp is 650 m.
It is important to adjust the volume from 1 to 700 ml.
The inventor has determined that the Canadian standard freeness is 650 ml or more, 700
It has been found that by using hemp pulp beaten to less than 0.1 ml and waste paper pulp together, low tear strength, which is a disadvantage of waste paper pulp, and deterioration of formation and high price due to poor dispersibility, which is a disadvantage of hemp pulp, have been found. Was. The importance of mild beating to hemp pulp and the blending effect with waste paper pulp will be described below.

The present inventor paid attention to the fiber length of hemp pulp and waste paper pulp. As a result of measuring the length-weighted average fiber length of the pulp by the optical automatic measurement method specified in 52, the hemp pulp was 3.4 to 3.8 mm, and the waste paper pulp was 0.6 to 1.0 mm. there were. As shown by the difference in fiber length, it is considered that the short fiber content of the waste paper pulp enhances the dispersibility of hemp pulp. Further, the present inventor has found that, even when beaten to a Canadian standard freeness of 650 ml or more and 700 ml or less as in the present invention, the average fiber length under load has no change compared to unbeaten hemp pulp. When the hemp pulp is beaten at a Canadian standard freeness of 650 ml or more and 700 ml or less, the dispersibility can be improved without impairing the strong tear strength which is an advantage of the hemp pulp.

In the present invention, when the Canadian standard freeness of hemp pulp is larger than 700 ml, the dispersion in the waste paper pulp is poor and the formation deteriorates, and the tear strength reaches a peak. 650ml or more, 700
The tear strength is worse than that of beating to less than ml due to the influence of the dispersion state of the hemp pulp. Canadian Standard Freeness 65
If the amount is less than 0 ml, the strength of the hemp pulp itself is reduced and the effect of the hemp pulp is not sufficiently exhibited. The beating machine can use a cylindrical type such as a beater and a deluxe finer, and a disk type such as a double disk refiner. In the case of a disk type, it is necessary to select a disk plate so as not to cause cutting beating, but the Canadian standard freeness is 650 ml or more. It is important to beat to 700 ml or less, and it is not limited by a beater or a beating method.

[0018] The content of hemp pulp is determined by forming a state in which the waste paper pulp having a short fiber length covers the periphery of the hemp pulp with respect to the skeletal fiber network of the hemp pulp in the paper layer structure. The content is 3% to 25%, preferably 5% to 15%, based on the total weight of the bone-dried pulp since a strong tear strength is maintained. If the content of hemp pulp is less than 3%, the effect of using hemp pulp will not be exhibited, and if it exceeds 25%, the tear strength will improve, but the formation of the paper will deteriorate, and the cost will increase significantly and the profit will increase. Will not fit.

On the other hand, the waste paper pulp used in the present invention is:
Used corrugated paper pulp, used paper pulp for magazines and newspapers, used white paper pulp and the like are not limited by the type of used paper.

Hemp pulp and waste paper pulp in the entire layer excluding the surface layer are 3% to 25% of hemp pulp and 7% waste paper pulp in terms of the absolute dry weight of hemp pulp and waste paper pulp.
It may be 5% to 97%, and hemp pulp and waste paper pulp are blended in all layers other than the surface layer to set a predetermined ratio, or the ratio is changed in each layer other than the surface layer, or the blending ratio of hemp pulp is 3 % To 25%, there is a method of providing a single layer of hemp pulp, and there is no limitation.

The multi-pack paper is in the form of a packaging container,
Depending on the number, various cuts and creases are applied to the paper, and further, packaging is applied. In the present invention, when the specific tear strength is 15 mN / g / m ² or more, the strength can be maintained after the package processing,
If it is less than N / g / m ² , the package will be damaged when handled roughly.

Due to its unique handling, the multipack may be placed in a humid atmosphere such as a refrigerator for a long time, or the bottom portion may be wet when stored in the refrigerator, resulting in deterioration of strength due to moisture absorption. Further, when the multi-pack is taken out of the refrigerator, the strength may be deteriorated due to the multi-pack being wetted by the dew water on the surface of the beverage can or the beverage bottle. It is desired that the residual tear strength when immersed in water is high in order to maintain the packaging form even when the paper strength is reduced due to moisture absorption and to protect the packaged object from rough handling. Therefore, in order to increase the residual tear strength, it is effective to internally add a moisture-proof or water-resistant synthetic resin, such as a rosin-based sizing agent, an alkyl ketene dimer, an alkenyl succinic anhydride, a wax, a styrene-based resin, and a melamine / formalin resin. It is necessary to use a sizing agent such as, but in the present invention, the effect of improving the tear strength of the hemp pulp itself, and the effect of improving the yield of the used chemicals, due to the waste paper pulp having a large surface area due to its fiber form. In addition, by blending hemp pulp and waste paper pulp as raw materials, the amount of chemicals such as moisture-proof or water-resistant synthetic resin can be reduced. In addition, there is no particular limitation on the addition of neutral paper, acid paper, or a sulfuric acid band, a wet paper strength enhancer, a paper strength enhancer, a retention aid, and the like. Further, the papermaking method is not subject to any restrictions.

Hemp pulp has the drawback that the fiber surface is long and rigid, so that the paper surface is poor in smoothness and the printability is poor. Therefore, when seeking multi-pack paper with good printability, virgin pulp should be hardwood bleached kraft pulp or softwood bleached kraft pulp, and used paper pulp should be high whiteness pulp. It is better to use However, if the surface properties and printability of the multi-pack paper can be improved by, for example, greatly increasing the amount of coating on the surface, hemp pulp may be added to the surface layer as necessary.

When a coating layer is provided for the purpose of improving printability, the coating composition is not particularly limited, but pigments include clay, calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, magnesium carbonate, and sulfuric acid. Calcium, barium sulfate, amorphous silica, styrene-based plastic pigment, urea-based plastic pigment, etc., binders such as starch, casein, polyvinyl alcohol, soy protein, slurylene-butadiene latex, vinyl acetate latex, urethane latex, etc. it can. In addition, a dispersant, a pH adjuster, a water retention agent, a lubricant, an antifoaming agent, a preservative, a fluorescent dye, a coloring pigment, a waterproofing agent, and the like can be used as necessary. The apparatus for coating is not particularly limited, and a blade coater, a rod coater, a roll coater, a gate roll coater, an air knife coater, a gravure coater, a size press, a champion coater, a simsizer and the like can be used.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these. In addition, all% in an Example and a comparative example show weight%.

The hemp pulp used in Examples and Comparative Examples of the present invention was Manila hemp (trade name: N-4) produced in Ecuador.
The conditions for pulping are as follows. 870 kg of absolutely dried Manila hemp was put into a 15 m ³ earth pot, and sodium sulfite was added at 18.0% based on the weight of absolutely dried Manila hemp.
5. The digestion was carried out at a maximum temperature of 162 ° C., a heating time of 60 minutes and a holding time at the maximum temperature of 90 minutes, followed by liquoring and washing to produce hemp pulp. From the hemp pulp, unbeaten hemp pulp (hereinafter hemp pulp A), hemp pulp lightly beaten to a Canadian standard freeness of 670 ml using a double disc refiner (hereinafter hemp pulp B), and a double disc refiner Hemp pulp (hereinafter, hemp pulp C) was beaten to a Canadian standard freeness of 600 ml. As the waste paper pulp, general magazine waste paper pulp was used.

Examples 1-2 The hardwood bleached kraft pulp (hereinafter referred to as LB)
KP 70%, softwood bleached kraft pulp (hereinafter NBK)
P) was blended at 30%, and as raw materials other than the surface layer, hemp pulp (B) 10% + magazine waste paper pulp 90% (Example 1)
20% hemp pulp (B) + 80% magazine waste paper pulp (Example 2), 0.16% of sulfuric acid band in terms of alumina, based on the absolute dry pulp weight of each raw material, rosin emulsion type internal sizing agent (SP manufactured by Arakawa Chemical Co., Ltd.
N-771) in an amount of 0.9% and a paper strength enhancer polyacrylamide (KW-320 manufactured by Arakawa Chemical Co., Ltd.) in an amount of 0.35% to obtain a surface layer of 50 g / m ² and a total weight of layers other than the surface layer. 285 g / m ² , and 15 g / m ^{2 of a} coating layer composed of titanium dioxide, kaolin, and styrene-butadiene latex was applied on the surface layer, and the basis weight was 350 g / m ^2.
Manufactured multi-pack paper. This multi-pack paper is conditioned in an environment of 20 ° C. and 65% RH for 48 hours or more.
The measurement of the tear strength and the calculation of the specific tear strength were performed according to IS P8116.

Example 3 A multi-pack paper was manufactured in the same manner as in Example 2 except that 100% Kent waste paper pulp was used as a raw material for the surface layer.
Evaluation was performed in the same manner as in Examples 1 and 2.

Example 4 As a raw material for the surface layer, hardwood bleached kraft pulp (hereinafter referred to as LB)
KP 70%, softwood bleached kraft pulp (hereinafter NBK)
P) is blended at 30%, and the raw material for the middle layer is hemp pulp (B) 20% + magazine pulp 80%, and the raw material for the back layer is deinked newspaper waste paper pulp 50% + softwood unbleached kraft pulp (hereinafter NUKP). ), The sulfuric acid band was 0.16% in terms of alumina, and the rosin emulsion-based internal sizing agent was 0.1% by weight based on the absolute dry pulp weight of each raw material.
9%, 0.35% of a paper strength enhancer polyacrylamide was added, and the total weight of the surface layer was 50 g / m ² and the middle layer was 245 g / m ² .
m ^2, subjected to Extract combined with backing layer 40 g / m ^2, titanium dioxide on the surface, kaolin, Suriren - a coating layer 15 g / m ² was applied consisting of butadiene latex, a basis weight of 350 g /
to produce a multi-pack paper m ^2. This multi-pack paper was evaluated in the same manner as in Examples 1 and 2.

Example 5 The same procedure as in Example 2 was carried out except that 95% of Kent waste paper pulp + 5% of hemp pulp (B) were used as the material for the surface layer, and the coating layer was 25 g / m ² , and the basis weight was 365 g / m ^{2. Two} multi-pack papers were manufactured. This multi-pack paper was used in Examples 1-2.
Was evaluated in the same way as

Comparative Example 1 Multi-pack paper was manufactured and evaluated in the same manner as in Examples 1 and 2, except that the raw material other than the surface layer was changed to NUKP 100%.

Comparative Example 2 A multi-pack paper was manufactured and evaluated in the same manner as in Examples 1 and 2, except that the raw materials other than the surface layer were 50% recycled pulp and 50% recycled corrugated cardboard.

Comparative Example 3 The raw materials other than the surface layer were NUKP 20% + magazine waste paper pulp 80
%, And a multi-pack paper was manufactured and evaluated in the same manner as in Examples 1 and 2.

Comparative Example 4 A multipack paper was produced and evaluated in the same manner as in Examples 1 and 2, except that hemp pulp (A) was used as the raw material other than the surface layer.

Comparative Example 5 A multipack paper was manufactured and evaluated in the same manner as in Examples 1 and 2, except that hemp pulp (C) was used as a raw material other than the surface layer.

Table 1 shows the measurement results obtained in the examples and comparative examples.

[0037]

[Table 1]

As is clear from Table 1, the multipack paper according to the present invention, in which hemp pulp which is slightly beaten to waste paper pulp as a raw material other than the middle layer, was produced by using multipack paper using NUKP or waste paper pulp alone. Higher tear strength than multi-pack paper.

According to the present invention, a large number of containers such as juice cans such as canned beer and soft drinks, small beverage cans such as small bottle drinks and beverage bottles are arranged in parallel and wrapped in a single paper sheet, and are stacked and packaged. To serve as a multi-pack used at the time,
Despite the use of waste paper, an effect of providing the most suitable paper having high tear strength is provided.

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) D21H 27/10 D21H 27/10

Claims (3)

[Claims] 1. A sheet for use in a multipack for storing and packaging a plurality of containers collectively, said sheet comprising at least two layers of assembling sheets, the side of which is not in contact with the containers when storing and packaging. A multi-pack paper comprising 3% to 25% hemp pulp and 75% to 97% waste paper pulp in the entire layer except the outermost layer. 2. The hemp pulp has a Canadian standard freeness of 65.
The multi-pack paper according to claim 1, wherein the multi-pack paper has a size of 0 ml or more and 700 ml or less. 3. The multi-pack paper according to claim 1, wherein the specific tear strength is 15 mN / g / m ² or more.