JPH05278153A - Water-resistant corrugated board sheet - Google Patents

Abstract

PURPOSE:To obtain a water-resistant corrugated board sheet easily dissolved in an alkali aqueous solution in a dissolving process (pulper device) of a papermaking raw material (old paper) and easily reused as resources in relation to a recent waste disposal problem in consideration of such a situation that a water-resistant corrugated cardboard sheet produced by impregnating a corrugated board sheet with a resin or wax must be uselessly subjected to disposal (incineration or landfilling) treatment for the reason that the water-resistant corrugated board sheet is hardly dissolved in the papermaking raw material dissolving process. CONSTITUTION:The liner paper or liner paper and core paper constituting a corrugated board sheet is coated or impregnated with an inorg. curing agent easy dissolve in an alkali aqueous solution and the coated or impregnated one is cured to provide a water-resistant corrugated board sheet not inferior to a conventional product in strength at the time of water immersion and easily reused as a papermaking raw material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-resistant corrugated cardboard sheet which can be easily recycled as a raw material for paper making, such as for packing fruits and vegetables containing a large amount of water and seafood.

[0002]

2. Description of the Related Art Conventionally, a water-resistant corrugated cardboard sheet (case) in which a corrugated cardboard sheet is impregnated with resin or wax has been widely used as a packaging box for fruits and vegetables containing a large amount of water. , For example, JP-A-50-90707
The publication discloses an invention of a water-resistant corrugated cardboard sheet having excellent strength when immersed in water, which is obtained by impregnating a corrugated cardboard sheet with a polyfunctional vinyl monomer, polymerizing it, and further sufficiently impregnating it with molten paraffin.

[0003]

In association with the recent problem of waste treatment related to the global environment, a corrugated cardboard sheet is impregnated with resin, wax, etc. because it is difficult to dissolve it in the step of dissolving the papermaking raw material. There is a problem in recycling the water-resistant corrugated cardboard sheet as a raw material for papermaking after use, and there is no choice but to dispose of valuable paper resources (incineration or landfill) without mischief. ) Dissolution process (Pulper device)
In the above, there is a demand for a water-resistant corrugated cardboard sheet which is easily dissolved in an alkaline aqueous solution and can be easily recycled.

[0004]

In view of the above demands for a water-resistant corrugated cardboard sheet that can be easily recycled, the present invention provides:
By applying or impregnating the liner paper or the liner paper and the core paper that compose the corrugated sheet with an inorganic curing agent that is easily dissolved in an alkaline aqueous solution, the strength when immersed in water is higher than that of conventional products. The present invention provides a water-resistant corrugated cardboard sheet that is comparable to the papermaking and can be easily recycled as a raw material for papermaking.

The inorganic hardener which is easily dissolved in an alkaline aqueous solution which is hardened by coating or impregnating the liner paper or the liner paper and the core paper constituting the corrugated board sheet of the present invention, is, for example, SiO ₂ or P ₂ O _5. , Al ₂ O ₃ , Fe ₂ O ₃ , PbO, T
A sol-like inorganic curing agent such as an alkali metal salt or a metal alkoxide prepared from an alkali-soluble inorganic oxide such as iO ₃ or B ₂ O ₃ is used.

That is, the formula (R₁)_mM₁(OR₂)_n, Formula (R₃)
_jM₂(OR_Four)_k, Formula (R_Five)_hM₃(OR₆) _iCompound represented by
(In the formula, R₁, R₃, R_FiveIs an alkyl group having 1 to 3 carbon atoms or bi
Nyl group, R₂, R_Four, R₆Is hydrogen, methyl, ethyl, isopropyl
L, t-butyl, etc., M₁Is calcium, barium, etc.₂
Is aluminum, etc.₃Is titanium, silicon, etc., m, j, h
Is 0 or 1, n is 1 or 2, k is 2 or 3, i is 3 or 4
, Or 2 or more types can be used in combination.
Which can be used by condensing two or more kinds
Is.

Specifically, Ca (OCH₃)₂, Ca (OC
₂H_Five)₂, Ca (OC₃H₇)₂, Ca (OC_FourH₉)₂, Ba (OC
H₃)₂, Ba (OC₂H_Five)₂, Ba (OC₃H₇)₂, Ba (OC
_FourH₉)₂, Al (OCH₃) ₃, Al (OC₂H_Five)₃, Al (OC
₃H₇)₃, Al (OC_FourH₉)₃, CH₃Al (OCH₃)₂, CH₃Al
(OC₂H_Five)₂, CH₃Al (OC₃H₇)₂, CH₃Al (OC_FourH₉)
₂, Si (OCH₃)_Four, Si (OC₂H_Five)_Four, Si (OC₃H₇)_Four, Si
(OC_FourH₉)_Four, CH₃Si (OCH₃)₃, CH₃Si (OC
₂H_Five)₃, CH₃Si (OC₃H₇)₃, CH₃Si (OC_FourH₉)₃, C₂
H_FiveSi (OCH₃)₃, C₂H_FiveSi (OC₂H_Five)₃, C₂H_FiveSi (O
C₃H₇)₃, C₂H_FiveSi (OC_FourH₉)₃, Ca (OH)₂, Ba (OH)
₂, Al (OH)₃, CH₃Al (OH)₂, Si (OH)_Four, CH₃Si
(OH)₃, C₂H_FiveSi (OH)₃Such as 1 type or 2 or more types
It can be used in combination.

More specifically, a compound obtained by condensing two or more kinds
As a compound, ZrOSi (OC₂H_Five) ₆, AlOSi (OC₂H
_Five)₆, TiOSi (OC₂H_Five)₆, (C₃H₇O)₃ZrOSi (OC₂
H_Five)₃, (C_FourH₉O)₃ZrOSi (OC₂H_Five)₃, (C₃H₇O)₃T
iOSi (OC₂H_Five)₃, (C_FourH₉O)₃TiOSi (OC₂H_Five)₃,
(C₃H₇O)₂AlOSi (OC₂H_Five)₃, (C_FourH₉O)₂AlOSi
(OC₂H_Five)₃And so on.

As for the inorganic type hardener of the present invention which is easily dissolved in an alkaline aqueous solution, the compound such as the above-mentioned alkali metal salt or metal alkoxide is mixed in water or an organic solvent or a mixed solvent thereof in the range of 5 to 95% by weight. By dissolving or dispersing and applying or impregnating the liner paper or the liner paper and the core paper which compose the corrugated board sheet in the sol state to cure, an inorganic curing agent when immersed in neutral water of the corrugated board sheet. 1 of cardboard sheet
The inorganic hardener dissolves easily when immersed in a caustic soda aqueous solution of about wt%, and its strength when immersed in water is comparable to conventional products, making it a water-resistant material that can be easily recycled as a raw material for papermaking. It is possible to provide a corrugated board sheet.

Preferred organic solvents include lower alcohols such as methanol, ethanol, propanol and butanol, ethylene glycol monoalkyl ether, diethylene glycol monoalkyl ether, propylene glycol monoalkyl ether and dipropylene glycol monoalkyl ether. Ether alcohols having methyl, ethyl, butyl and the like as an alkyl group, acetic acid of the above ether alcohols such as ethylene glycol monoalkyl ether acetate, diethylene glycol monoalkyl ether acetate, propylene glycol monoalkyl ether acetate and dipropylene glycol monoalkyl ether acetate Esters, Ethoxyethyl alcohol acetate, Methyl acetate, Ethyl acetate, Procetic acid Le, in which like can be used alcohols acetic esters or acetone, such as butyl acetate.

The liner paper or the liner paper and the core paper constituting the corrugated cardboard sheet which is coated or impregnated with the inorganic type curing agent which is easily dissolved in the alkaline aqueous solution of the present invention, are ordinary liner paper and core paper. Can be used without any restrictions, and at the same time as the liner paper and the core paper are made, or in a separate step, by an appropriate method such as a double-sided roll coat method, and in some cases, pasted on a corrugated cardboard sheet. After that, 5 by an appropriate method such as impregnation
-40 wt% (based on the weight of liner paper and core paper, each dry base) of an inorganic curing agent is applied or impregnated and dried by warm air (about 120 ° C) to cure.

[0012]

【Example】

<Example 1> 200 g / m ² front liner paper in a roll shape and
With the backing liner paper core paper and 200 g / m ² in a 200 g / m ^2, an inorganic hardening agent having the following constitutions, respectively 30 wt% in a conventional double-sided roll coater (Table liner paper, corrugating medium Apply it so that it is each dry base, based on the weight of the backing liner paper,
After impregnating and heating and drying with warm air of 120 ° C. for 3 minutes to cure, they were laminated with a normal corrugator device to prepare an A-flute double-sided waterproof corrugated cardboard sheet having a thickness of 4.6 mm in this example. ..

Composition of the curing agent a. Tetraethoxysilane Si (OC ₂ H ₅ ) ₄ 70.0% by weight b. Colloidal alumina Al ₂ O ₃ 0.1% by weight c. Ethyl alcohol C ₂ H ₅ OH 15. 0% by weight d. Purified water H ₂ O 14.9% by weight

For comparison, the same front liner paper, core paper, and back liner paper as described above are used to bond with the same corrugator device without applying and impregnating the inorganic curing agent. A comparative A-flute double-sided ordinary corrugated board sheet having a thickness of 4.6 mm was prepared.

Next, the water-resistant corrugated cardboard sheet of this example and the ordinary corrugated cardboard sheet of the comparative product were left at room temperature at 23 ° C.
(Relative humidity 65%), 10 minutes neutral water immersion (water temperature 23 ℃), 60 minutes neutral water immersion (water temperature 23
(° C), the burst strength and impact puncture strength, which are general strength test methods for corrugated cardboard sheets, were measured.
When left at room temperature, the strength was comparable to that of the comparative ordinary corrugated board sheet, and when immersed in neutral water for 10 minutes and 60 minutes, the strength deteriorated due to immersion in neutral water. It was hardly recognized. Table 1 shows the measurement results of the burst strength (JIS-P-8131) and the impact drilling strength (JIS-P-8134).

[0016]

[Table 1]

Subsequently, with respect to each of 100 sheets of the water-resistant corrugated cardboard sheet of this example and a normal corrugated cardboard sheet of a comparative product, which were cut into 20 cm × 20 cm pieces, a melting step (pulper device) of a papermaking raw material (waste paper) in a papermaking factory. The same as above, but put into a reflux tank filled with a 1 wt% caustic soda aqueous solution,
When heated to 95 ° C. and stirred, they were completely dissolved in about 5 minutes, respectively, and in the water resistant corrugated cardboard sheet of this example, no suspended matter or precipitate such as an inorganic curing agent film was observed.

<Example 2> Two A-flute double-sided ordinary corrugated cardboard sheets having a thickness of 4.6 mm prepared in Example 1 were prepared.
After cutting into 0 cm × 20 cm and protecting the cut surface with a tape in a liquid-tight manner, an inorganic oxidant having the same structure as that of Example 1 was used in an amount of 30% by weight (per weight of corrugated cardboard sheet, dry It was coated and impregnated so that it would be a base), and was heated and dried with warm air at 105 ° C. for 10 minutes to be cured to prepare a 4.6 mm-thick A-flute double-sided waterproof corrugated board sheet of this example.

Next, the water-resistant corrugated cardboard sheet of this example was left at room temperature at 23 ° C. (relative humidity 6) as in Example 1.
5%), 10 minutes of neutral water immersion (water temperature 23 ° C), and 60 minutes of neutral water immersion (water temperature 23 ° C) according to the general strength test method for corrugated board sheets. When a certain burst strength and impact puncture strength were measured, the water-resistant corrugated cardboard sheet of this example, like the water-resistant corrugated cardboard sheet of Example 1, was a comparative normal cardboard sheet when left at room temperature at 23 ° C. Compared to the strength at all,
In the case of immersion for 10 minutes and 60 minutes in neutral water, almost no deterioration in strength due to immersion in neutral water was observed. Burst strength (JIS-P-8131) and impact drilling strength are shown in Table 1 of Example 1.
The measurement results of (JIS-P-8134) are shown.

Subsequently, with respect to 100 sheets of the water-resistant corrugated cardboard sheet of this embodiment having a size of 20 cm × 20 cm, in the same manner as in Example 1, the same step (pulper device) for dissolving the papermaking raw material (waste paper) in the papermaking plant was used. It was put into a reflux tank filled with a wt% caustic soda aqueous solution, heated to 95 ° C. and stirred, and it was completely dissolved in about 5 minutes, and there were no floating substances or precipitates such as an inorganic curing agent film. I was not able to admit.

[0021]

As described above, as shown in the examples, the water-resistant corrugated cardboard sheet of the present invention has a strength comparable to that of the ordinary corrugated cardboard sheet when left at room temperature, and when it is immersed in neutral water. Shows almost no deterioration in strength due to immersion in neutral water (comparable in strength to the conventional water-resistant corrugated cardboard sheet shown in Table 1 as a reference value). It was completely dissolved in a caustic soda aqueous solution of about wt% in a short time and no suspended matter or precipitate such as an inorganic cured film was observed at all.

That is, in the water resistant corrugated cardboard sheet of the present invention, the liner paper or the liner paper and the core paper constituting the corrugated cardboard sheet is used as an inorganic curing agent which is easily dissolved in an alkaline aqueous solution instead of the conventional resin or wax. By applying or impregnating it with water and curing it, the strength when immersed in water is comparable to that of conventional products, and the same caustic soda solution of about 1% by weight as in the dissolving process of papermaking raw materials in paper mills is used. It is easily dissolved and easily recycled as a papermaking raw material.

Further, the water-resistant corrugated cardboard sheet of the present invention can be applied and impregnated in a paper making process such as liner paper or core paper, so that it does not require special equipment or equipment and the manufacturing cost is low. Since there is no restriction on the paper such as liner paper and core paper, it can be applied to a wide range of applications such as paperboard, hardboard and paper honeycomb.In addition, the water resistant corrugated cardboard sheet of the present invention is hygienic. It is harmless to fire and is flame retardant for disaster prevention.

Claims (1)

[Claims] 1. A water-resistant corrugated cardboard sheet characterized in that a liner paper or a liner paper and a core paper constituting a corrugated board sheet is coated or impregnated with an inorganic curing agent which is easily dissolved in an alkaline aqueous solution to cure.