JP2000141518A - Strongly water resistant corrugated fiberboard and strongly water resistant corrugated fiberboard case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recyclable strongly water resistant corrugated fiberboard adapted to a material of a so-called ice packed transporting corrugated fiberboard case capable of transporting perishable foodstuff such as particularly fruit and vegetable, fresh fish, meat and the like together with ice in a freshness holding transporting corrugated fiberboard case and the strongly water resistant corrugated fiberboard case. SOLUTION: In the corrugated fiberboard obtained by laminating liners on both surfaces of a corrugating core obtained by step feeding and molding a corrugating base sheet, water repellency (JISP8137) of at least one surface of the corrugating base sheet is R6 to R9, the water repellency of the outside surface of the liner is R6 or above, the core and the liners are adhered by a corrugated fiberboard adhesive containing a synthetic resin emulsion containing a carboxyl group, starch, thermosetting resin and a crosslinker, and 60 min water immersion adhesive strengths (JISZ0402) of the core and the liner are 4 kgf or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cardboard box for transporting freshness, especially a so-called ice-packed cardboard box for transporting fresh foodstuffs such as fruits and vegetables, fresh fish, meat, etc. together with ice. The present invention also relates to a recyclable, highly water-resistant cardboard and a strongly water-resistant cardboard box.

[0002]

2. Description of the Related Art It has been known that low-temperature transportation is effective for transporting fresh foods such as fruits and vegetables, fresh fish and meat while maintaining freshness. Therefore, it is effective to store and transport fresh food items using a refrigerator or a refrigerator car, and to keep the fresh food items at a low temperature during the entire transportation process. However, this system is not sufficiently provided.

Therefore, a method of transporting certain fresh foods, for example, fresh fish, and certain vegetables such as broccoli, together with ice, is used. However, when ice is put into a generally used cardboard box, the water in which the ice melts penetrates the cardboard, causing a significant deterioration in strength, and as a result, there is a problem that the cardboard box is crushed.

In order to prevent this problem, a corrugated cardboard box made of a corrugated cardboard sheet having a water repellent or water resistant liner may be used. The liner is sucked into the glue, and as a result, the box is crushed due to the deterioration in strength, and the core and the liner are peeled off. For these reasons, conventional packaging boxes for transporting fresh food on ice are:
Styrofoam boxes and cardboard boxes impregnated with wax have been used.

[0005] Styrofoam boxes have the problem that they are not foldable and take up space for transportation and storage, and that the recycling system is not fully established, making it difficult to recycle. Further, the wax impregnated cardboard cannot be recycled as waste paper. Furthermore, if wax-impregnated cardboard is mistakenly mixed with normal cardboard and collected as waste paper, paper breakage occurs during the papermaking process of recycled paper, and black wax spots appear on the product, significantly reducing the commercial value. Occurred.

[0006]

SUMMARY OF THE INVENTION According to the present invention, there is provided a highly water-resistant corrugated cardboard sheet which has a high level of water resistance suitable for ice-packed transportation of fresh food products, and which can be recovered as used paper after being used as cardboard and recycled. And a highly water-resistant cardboard box.

[0007]

The present invention has the following configuration to solve the above problems. That is, the present invention relates to a corrugated cardboard obtained by laminating liners on both sides of a core obtained by step-forming a core base paper, and the water repellency (JI) of at least one surface of the core base paper.
SP8137) is R6 to R9, the water repellency of the outer surface of the liner is R6 or more, and a corrugated cardboard adhesive containing a synthetic resin emulsion containing carboxyl groups, starch, a thermosetting resin, and a cross-linking agent is used as a core. The liner is glued,
60-minute immersion adhesive strength between the core and the liner (JISZ04
02) is 4 kgf or more.

Further, a second aspect of the present invention is a strong water-resistant cardboard box for ice-packed transportation, characterized by using the above-mentioned strong water-resistant cardboard as a material.

[0009]

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

The water repellency of at least one side of the core base paper is R6
Otherwise, moisture is absorbed from the core of the corrugated cardboard, and the strength of the corrugated cardboard sheet is degraded. If the cardboard box obtained from such a corrugated cardboard sheet is packed with ice and transported, the box collapses. Further, when the water repellency of the core exceeds R9, there is a problem that the adhesiveness is remarkably deteriorated when laminating as a corrugated cardboard sheet.

If the water repellency of the outer surface of the liner is less than R6, moisture is absorbed from the surface of the corrugated cardboard sheet to deteriorate the strength of the corrugated cardboard sheet. When transported, boxes collapse. In addition, the liner outer surface refers to the liner surface on the side that is outside the corrugated cardboard sheet when the liner and the core are pasted to obtain a corrugated cardboard sheet.

If the core and the liner base paper have a 60-minute submersion adhesive strength of 4 kgf or more, the core and the liner do not come off when the corrugated cardboard sheet obtained by lamination is wet with water.
A cardboard sheet excellent in strength and appearance can be obtained, and a cardboard box made of such a cardboard sheet can be used for applications that require a high degree of water resistance, such as ice-packed transportation of fresh food products. It has become possible. Further, the recycling of used paper in the present invention means that the used paper is pulverized by a pulper and reused as pulp. The corrugated cardboard sheet of the present invention can be easily pulverized by a normal pulper and is therefore recyclable.

In the present invention, the water-resistant adhesive used for bonding the liner and the core is a synthetic resin emulsion containing a carboxyl group, starch, a cardboard adhesive containing a thermosetting resin and a crosslinking agent. Use agent.

The synthetic resin emulsion is obtained by carboxylizing a styrene-butadiene copolymer (SBR), an acrylonitrile-butadiene copolymer (NBR), a methyl methacrylate-butadiene copolymer (MBR), or the like. Can be used. Further, two or more of these synthetic resin emulsions may be arbitrarily selected and used by mixing. Commercially available synthetic resin emulsions include XA-771 as SBR.
1 (Asahi Kasei Kogyo), NBR 1571 as NBR
(Nippon Zeon), Polyrac 525-8 as MBR
(Mitsui Toatsu Chemicals) and the like are known.

The starch can be arbitrarily used as long as it can be generally used for an adhesive for cardboard. Examples of the thermosetting resin include formaldehyde resins such as a urea resin, a phenol resin, a resorcinol resin, a ketone resin, and a melamine resin. As the crosslinking agent,
Polyamide epoxy which is a compound having an epoxy group,
Hexamethylenetetramine, which is a compound having an alkoxymethyl group, such as diethylenemethane diisocyanate, which is a compound having an isocyanate group, such as diphenylmethane diisocyanate and tolylene diisocyanate, which are compounds having an isocyanate group, such as polyethylene glycol diepoxide and bisphenol A glycidyl ether; ,
Zinc oxide which is a metal salt such as methoxymethylol urea,
Examples thereof include zinc ammonium acetate and ammonium zirconium carbonate.

In the present invention, in order to impart water repellency to the surface of the liner base paper and the core base paper, a known water repellent can be applied to the surface of the base paper by means of coating or spraying. The liner base paper and the core base paper used in the present invention are more preferably a water-resistant liner base paper and a water-resistant core base paper. The water-resistant liner and the water-resistant core are defined as two lines when the ring crush strength of the liner and the core according to JISP8126 is 100%.
Ring crush strength after immersion in water at 20 ° C. for 4 hours is 10% or more.

When the cardboard box obtained in the present invention is used for ice-packing transportation, a water absorber such as a paper material, a pulp material, or a polymer absorber is placed at the bottom of the box to prevent the outflow of water. It is further desirable to prevent. Further, the corrugated cardboard sheet in the present invention may be any one 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)
Oji SK280 (outside water repellency R8 to R
9) Hokuyo H as liner for double facer (DF)
PW290 (outside water repellency R8 to R10), Hokuyo water-resistant core HP200 having a water repellency of R8 on both sides as a core, and bonding these with a water-resistant adhesive obtained by a method described later. A corrugated cardboard sheet of A flute was manufactured, and the obtained corrugated cardboard sheet was designed so that the double facer side liner was outside the box, type 0201, L / W / D
= 450 mm / 300 mm / 270 mm cardboard boxes were made.

[Production Method of Water-Resistant Adhesive] A starch slurry consisting of 1,125 g of premixed starch (91% by weight of corn starch, 7% by weight of α-starch, 2% by weight of borax) and 2265 g of water was mixed with SBR latex (XA- manufactured by Asahi Kasei Corporation). 77
11: solid content 50%, carboxyl group content 2%, Tg
(−12 ° C.), 750 g is added, and 204 g of 15% caustic soda is further added with stirring, and a ketone resin (manufactured by Oji Cornstarch, waterproofing agent A) is further used as a thermosetting resin.
Was added at 3% by weight based on the total solids, and an epoxy compound (Euramine P-5600, manufactured by Mitsui Toatsu Chemicals) was added as a crosslinking agent at 4% by weight based on the total solids to obtain a water-resistant adhesive.

Example 2 A cardboard sheet was manufactured and a cardboard box was prepared in the same manner as in Example 1 except that the water repellency of the core was changed to R0 on one side and R8 on the other side.

Example 3 A water absorber (water absorption capacity 4 kg) composed 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 (water absorption capacity 4 kg) composed of pulp and a polymer absorber was placed in the bottom of a 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 corrugated cardboard bonding (Honen HR1
A cardboard sheet was manufactured and a cardboard box was prepared in the same manner as in Example 1 except that the 60-method was used.

Comparative Example 2 As a water-resistant adhesive for bonding,
Water-resistant adhesive for corrugated cardboard bonding (Honen HR1
A cardboard sheet was manufactured and a cardboard box was prepared in the same manner as in Example 2 except that the 60-method was used.

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

Comparative Example 4 A water absorber (water absorption capacity of 4 kg) composed of pulp and a polymer water absorber was placed in the bottom of a 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 cardboard boxes obtained in the examples and comparative examples, sealed, the boxes were stacked in four steps, and 100 k of the boxes were further placed thereon.
g and a 120 kg load was applied to the lowermost stage, and stored in a room at 20 ° C. for one day. Thereafter, the presence or absence of collapse of the cardboard box and the occurrence of peeling of the core and the liner were evaluated.

Table 1 shows the evaluations of Examples 1 to 4 and Comparative Examples 1 to 4.

[0030]

[Table 1]

As is clear from the table, in the example, there was no collapse of the box and no peeling of the core and the liner, the broccoli as the contents 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 separated, which is not preferable as a cardboard box for ice-packing transportation.

[0032]

Industrial Applicability According to the present invention, a highly water-resistant corrugated cardboard sheet which has high water resistance suitable for ice-packed transportation of perishable foods and the like, and which can be recovered as used paper after being used as corrugated cardboard and recycled. It is possible to obtain a cardboard box.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3E078 BB03 BB24 BB44 BB45 BB46 BC01 CC22X 4F100 AJ07G AK01G AK53G AK54G AN02G BA03 BA06 BA10B BA10C CA02G CB00 J CB05 DD12A DG10A DG10B06 J05B06 J05B06 J05B06 JM01G YY00 YY00A YY00B YY00C 4J040 BA111 BA112 CA061 CA062 CA071 CA072 CA081 CA082 EB031 EB032 EB061 EB062 EB111 EB112 EB131 EB132 EC062 EC252 EC282 EF181 EF201 EL031 EL032 HC07 HC07 HC20

Claims (2)

[Claims] 1. A corrugated cardboard in which liners are bonded to both surfaces of a core obtained by step-forming a core base paper, wherein the water repellency (JISP8137) of at least one surface of the core base paper is R6 to R9, and the outside of the liner is provided. The core and the liner are bonded by a corrugated cardboard adhesive containing a synthetic resin emulsion containing carboxyl groups, starch, a thermosetting resin, and a cross-linking agent, having a water repellency of R6 or more on the side surface. A strong water-resistant corrugated cardboard characterized by having a 60-minute immersion adhesive strength (JISZ0402) of 4 kgf or more. 2. A highly water-resistant corrugated cardboard box for ice-packed transportation, characterized by using the strongly water-resistant corrugated cardboard according to claim 1.