JP3500988B2 - Strong waterproof cardboard and strong waterproof cardboard box - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable as a material for a corrugated cardboard box for transportation of freshness, and particularly a so-called corrugated cardboard box for transportation, in which fresh food such as fruits and vegetables, fresh fish and meat can be packaged together with ice for transportation. The present invention also relates to a recyclable strong waterproof cardboard box and a strong waterproof cardboard box.

[0002]

2. Description of the Related Art Conventionally, it has been known that low temperature transportation is effective for transporting fresh foods such as fruits and vegetables, fresh fish and meats while maintaining their freshness. Therefore, it is effective to store and transport fresh food products using a refrigerator or a refrigerating vehicle and keep the fresh food products at a low temperature during the entire transportation process, but this system is not sufficiently developed.

[0003] Therefore, a method of transporting some kinds of fresh foods such as fresh fish and some vegetables such as broccoli in a box together with ice is adopted. However, when ice is put in a commonly used cardboard box, water in which the ice melts penetrates into the cardboard, resulting in significant deterioration in strength, resulting in a problem that the cardboard box is crushed.

In order to prevent this problem, a corrugated board box made of a corrugated board sheet having a liner having water repellency or water resistance may be used. In these cases, however, water in which ice is melted into the core and the core is used. The liner was sucked into the adhesive, and as a result, the box was crushed due to strength deterioration and the core and the liner were separated, which was a problem. For these reasons, conventional ice-packed shipping boxes for fresh food products are:
Styrofoam boxes and cardboard boxes impregnated with wax have been used.

Since the Styrofoam box cannot be folded, it requires space for transportation and storage, and has a problem that it is difficult to recycle it because the recycling system is not well established. Also, wax-impregnated corrugated board cannot be recycled as used paper. Furthermore, if wax-impregnated corrugated cardboard is mistakenly mixed with normal corrugated cardboard and collected as waste paper, paper breaks may occur in the paper making process of recycled paper, and spots of black wax may appear on the product, significantly reducing the commercial value. Occurred.

[0006]

According to the present invention, a strong water resistant corrugated cardboard sheet having a high degree of water resistance suitable for ice-packed transportation of fresh food products and being recyclable after being used as cardboard and recovered as waste paper, And a strong waterproof cardboard box.

[0007]

In order to solve the above problems, the present invention has the following constitution. That is, the present invention is a corrugated cardboard in which a liner is attached to both sides of a core formed by step-forming the core raw paper, and the water repellency (JI
SP8137) is R6 to R9, the water repellency of the outer surface of the liner is R6 or more, and a corrugated adhesive containing a carboxyl group-containing synthetic resin emulsion, starch, thermosetting resin and cross-linking agent is used to form a core. The liner is attached,
60-minute water immersion adhesive strength between the core and the liner (JISZ04
02) is 4 kgf or more, which is a strong waterproof cardboard.

A second aspect of the present invention is a strong water resistant corrugated board box for ice-packed transportation, characterized by using the strong water resistant corrugated board as a material.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a corrugated board in which the water repellency of at least one surface of a core raw paper is R6 to R9 and the water repellency of the outer surface of the liner is R6 or more.

The water repellency of at least one side of the core raw paper is R6.
If the above is not the case, moisture will be absorbed from the corrugated fiberboard core to deteriorate the strength of the corrugated fiberboard sheet, and if the corrugated fiberboard box obtained from such corrugated fiberboard is ice-packed and transported, box collapse occurs. Further, if the water repellency of the core exceeds R9, there arises a problem that the adhesiveness is markedly deteriorated when the core is laminated as a corrugated board sheet.

When the water repellency of the outer surface of the liner is less than R6, the strength of the corrugated cardboard sheet is deteriorated due to absorption of water from the corrugated cardboard sheet surface, and the corrugated cardboard box obtained from such corrugated cardboard sheet is packed with ice. Boxes collapse when transported. The outer surface of the liner refers to the liner surface on the outer side of the corrugated cardboard sheet when the liner and the core are bonded together to obtain a corrugated cardboard sheet.

If the 60-minute water immersion adhesive strength between the core and the liner base paper is 4 kgf or more, the core and the liner are not peeled off when the corrugated cardboard sheet obtained by lamination is wet.
Cardboard sheets with excellent strength and appearance can be obtained, and cardboard boxes made from such cardboard sheets can be used for applications requiring high water resistance such as transportation of ice-packed fresh food products. It has become possible. Further, the recycling of used paper in the present invention means that the used paper is disintegrated with a pulper and reused as pulp, but the corrugated cardboard sheet of the present invention can be easily disintegrated with an ordinary pulper and therefore can be recycled.

The water-resistant adhesive used to bond the liner and the core in the present invention includes a synthetic resin emulsion containing a carboxyl group, starch, an adhesive for corrugated board containing a thermosetting resin and a cross-linking agent. Use agents.

As the synthetic resin emulsion, styrene-butadiene copolymer (SBR), acrylonitrile-butadiene copolymer (NBR), methylmethacrylate-butadiene copolymer (MBR), etc. are carboxylated. Can be used. Further, two or more kinds of these synthetic resin emulsions may be arbitrarily selected and mixed and used. Commercially available products of these synthetic resin emulsions include SBR XA-771.
1 (Asahi Kasei Corporation), NBR 1571 as NBR
(Zeon Japan), Polylac 525-8 as MBR
(Mitsui Toatsu Chemicals) and the like are known.

As the starch, any starch can be used as long as it can be usually used in an adhesive for corrugated board. Examples of the thermosetting resin include formaldehyde resins such as urea resin, phenol resin, resorcinol resin, ketone resin and melamine resin. As the cross-linking agent,
Polyamide epoxy which is a compound having an epoxy group,
Hexamethylenetetramine, which is a compound having an alkoxymethyl group, such as polyethylene glycol diepoxide, bisphenol A glycidyl ether, a compound having an isocyanate group, such as diphenylmethane diisocyanate, tolylene diisocyanate, a compound having an ethyleneimine group, such as a diethyleneimine compound ,
Zinc oxide, which is a metal salt such as methoxymethylolurea,
Examples include zinc ammonium acetate, ammonium zirconium carbonate, and the like.

In the present invention, in order to impart water repellency to the surfaces of the liner raw paper and the core raw paper, a known water repellent agent can be applied by being carried on the surface of the raw paper by means such as coating or spraying. Further, the liner base paper and the core base paper used in the present invention are more preferably water-resistant liner base paper and underwater core base paper. The water resistant liner and the underwater resistant core mean that the liner and the core are 2 when the ring crush strength according to JIS P8126 of the liner and the core is 100%.
The ring crush strength after immersion in water at 20 ° C. for 4 hours is 10% or more.

When the corrugated cardboard box obtained by the present invention is used for ice-packed transportation, a water absorbent such as a paper material, a pulp material, or a polymer absorbent is put in the bottom of the box to prevent the outflow of water. It is more desirable to prevent. Further, the corrugated board sheet in the present invention may be any of A flute, B flute, AB flute and the like. Further, the shape of the cardboard box in the present invention can be arbitrarily designed as needed.

[0018]

The present invention will be described in more detail with reference to the following examples.

<Example 1> Single facer (SF)
Prince SK280 as the side liner (Outer water repellency R8-R
9), Hokuyo H as a double-facer (DF) side liner
PW290 (outer water repellency R8 to R10), using a water repellent R8 on both sides of the Hokuyo water resistant core HP200 as the core, and bonding these with a water resistant adhesive obtained by the method described below. A corrugated cardboard sheet of A flute is manufactured, and the liner on the double facer side of the corrugated cardboard sheet obtained is outside the box 0201 type, L / W / D
= 450mm / 300mm / 270mm cardboard box was created.

[Production Method of Water-Resistant Adhesive] A starch slurry comprising 1125 g of premixed starch (corn starch 91% by weight, α starch 7% by weight, borax 2% by weight) and 2265 g of water was added to SBR latex (XA- manufactured by Asahi Kasei Kogyo Co., Ltd. 77
11: Solid content 50%, carboxyl group content 2%, Tg
-12 ° C.) 750 g, and 15 g of caustic soda 204 g with a concentration of 15% are added while stirring. Further, a ketone resin (manufactured by Oji Corn Starch, waterproofing agent A) as a thermosetting resin.
Was added to the total solid content in an amount of 3% by weight, and an epoxy compound (Euramine P-5600 manufactured by Mitsui Toatsu Chemical Co., Inc.) as a crosslinking agent was added in an amount of 4% by weight to the total solid content to obtain a water resistant adhesive.

<Example 2> A corrugated board sheet was manufactured in the same manner as in Example 1 except that the water repellency of the core was set to R0 on one side and R8 on the other side, to prepare a corrugated board box.

<Example 3> A water absorber (moisture absorption capacity of 4 kg) consisting of pulp and a polymer water absorber was placed in the bottom of a cardboard box manufactured in the same manner as in Example 1.

<Example 4> A water absorber (moisture absorption capacity of 4 kg) consisting of pulp and a polymer absorber was placed in the bottom of a corrugated cardboard box manufactured in the same manner as in Example 2.

<Comparative Example 1> As a water-resistant adhesive for bonding,
Water resistant adhesive for normal corrugated board bonding (Hosei HR1
A corrugated board sheet was produced in the same manner as in Example 1 except that the 60-system) was used to produce a corrugated board box.

<Comparative Example 2> As a water resistant adhesive for bonding,
Water resistant adhesive for normal corrugated board bonding (Hosei HR1
A corrugated board sheet was manufactured in the same manner as in Example 2 except that the 60-system) was used to prepare a corrugated board box.

<Comparative Example 3> A water absorbent (water absorption capacity of 4 kg) consisting of pulp and a polymer water absorbent was placed in the bottom of a corrugated cardboard box manufactured in the same manner as in Comparative Example 1.

<Comparative Example 4> A water absorber (moisture absorption capacity of 4 kg) consisting of pulp and a polymer water absorber was placed in the bottom of a corrugated cardboard box manufactured in the same manner as in Comparative Example 2.

[Evaluation Method] 5 kg of broccoli and 4 kg of ice were put into the corrugated cardboard boxes obtained in Examples and Comparative Examples, sealed, and the boxes were stacked in four stages, and further 100 k from the top.
A load of g was applied, and a load of 120 kg was applied to the lowermost stage, and the sample was stored in a room at 20 ° C. for 1 day. Then, the presence or absence of crushing of the cardboard box and the presence or absence of peeling of the core and the liner were evaluated.

Evaluations of Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1.

[0030]

[Table 1]

As is clear from the table, in the examples, the box was not crushed and the core and the liner were not peeled off, and the broccoli, which was the content, was protected, and the overall evaluation as a cardboard box for ice-packed transportation was good. is there. On the other hand, in the comparative example, the box is crushed and the core and the liner are peeled off, which is not preferable as a cardboard box for ice-packed transportation.

[0032]

Industrial Applicability According to the present invention, a strong water-resistant corrugated cardboard sheet having a high degree of water resistance suitable for transportation of iced fresh foods, etc., and being recyclable after being used as corrugated cardboard and recovered as waste paper, and strong water resistance. It is possible to get a cardboard box.

Continuation of the front page (56) Reference JP-A-10-226001 (JP, A) JP-A-8-34827 (JP, A) JP-A-60-168773 (JP, A) JP-A-5-214306 (JP , A) JP-A-50-129631 (JP, A) JP-B 44-17036 (JP, B1) JP-B 48-40465 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB) (Name) B32B 1/00-35/00 C09J 9/00-201/10

Claims (2)

(57) [Claims] 1. A corrugated cardboard in which a liner is bonded to both sides of a core formed by step-forming a core raw paper, wherein at least one surface of the core raw paper has a water repellency (JISP8137) of R6 to R9, and the outside of the liner. The core and the liner are bonded together by a corrugated cardboard adhesive having a side surface water repellency of R6 or more and containing a carboxyl group-containing synthetic resin emulsion, starch, thermosetting resin and cross-linking agent. A 60-minute water-immersed adhesive strength (JIS Z0402) of 4 kgf or more is a strong waterproof cardboard. 2. A strong water-resistant corrugated board box for ice-packed transportation, which is made of the strong water-resistant corrugated board according to claim 1.