JPS60224537A - Reinforced corrugated board and reinforced corrugated board vessel using said board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to reinforced cardboard and a reinforced cardboard container manufactured using the same.

More specifically, the present invention relates to reinforced cardboard reinforced with a polyincyanate composition and whose adhesion is strengthened by a reaction between an uncured product of this composition and an uncured adhesive, and a reinforced cardboard container using the same.

Conventionally, one side of liner paper, core paper, or both
It is already well known that cardboard, whose entire surface or a portion thereof has been reinforced, is used as the core of interior materials, miscellaneous goods, etc., or boxes are assembled with this reinforced cardboard to package and transport heavy items. It is also known that the strength of corrugated cardboard that has been subjected to the reinforcement treatment is significantly improved. Furthermore, it is known that polyisocyanate monomers, oligomers, and bleed polymers are particularly effective as reinforcing agents.

The method of applying a reinforcing agent to the surface of cardboard requires a large area to install a reinforcing agent treatment process separate from the cardboard manufacturing equipment. In addition, in the method of manufacturing corrugated cardboard using pre-strengthened base paper, the base paper loses its water absorbency, and the commonly used starch-based adhesives lack adhesive strength at the stage of laminating liner paper and core paper. Therefore, there were many problems such as the need to use expensive special adhesives.Furthermore, when trying to apply polyinsyanates on a corrugated board manufacturing line, there was a problem with the adhesion between the liner paper and the core paper, so special measures were required. It becomes necessary.

As a result of various studies in order to solve these problems in the strength and manufacturing of corrugated cardboard, the present inventors have developed a polyisocyanate composition as described below to produce core paper and liner on the corrugated cardboard production line widely used in the industry. By applying it to at least one of the inner surfaces of the paper (hereinafter simply referred to as the inner surface of the core paper and/or the liner paper), or by adhering with a commonly used inexpensive starch-based adhesive. Not only that, but surprisingly, the reaction between the polyisocyanate and the adhesive occurs at the same time, thereby imparting water resistance to the bonded area and increasing its strength at the same time, leading to the discovery of the present invention.

That is, the present invention provides (1) applying a polyisocyanate composition or a solution thereof to at least one of the inner surfaces of the core paper and the liner paper, and applying the uncured polyisocyanate composition and the inner surface of the core paper. A reinforced billboard made by bonding the corrugated top part of the core paper and the liner paper with an uncured adhesive containing active hydrogen applied to the corrugated top part.

(2) A polyisocyanate composition or a solution thereof is applied to at least one of the inner surfaces of the core paper and the liner paper, and the uncured polyisocyanate composition and the active material are applied to the top of the corrugated core paper. The core paper is made of hydrogen-containing uncured adhesive.

The organic polyinsocyanate used in the present invention is tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HDI).
), rose phenylene diincyanate, lysine diincyanate (LDI), dicyclohexylmethane-4,4
-diincyanate (hydrogenated MDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), hydrogenated xylylene diisocyanate (HXDI), crude tolylene diisocyanate, crude diphenylmethane diincyanate [polymethylene poly Phenyl polyisocyanate 3
and other known aliphatic, aromatic, polyisocyanates and their crude products, or diurethane-modified, carbodiimide-modified, biuret-modified, incyanurate-modified parts of these di- or polyisocyanates by known methods, such as carbodiimide. Trimethylolpropane adduct of modified MDI%TDI, water modified biuret structure HD
Known aliphatic, aromatic, alicyclic polyisocyanates such as I-modified products, 〉J+; (・ra+ItrS,.

Examples of isocyanate-based urethane modifiers include polyoxyalkylene polyols such as glycerin, trimethylolpropane, hexanetriol, sucrose, etc., alone or in mixtures, and ethylene oxide, propylene oxide, etc. These polyethers are terminal OH group-containing polyethers to which one or more types have been added.These polyethers can be used alone or in combination of two or more types.

Particularly preferred is crude diphenylmethane diisocida/anate, which exhibits excellent performance in the production of reinforced corrugated board by the method of the present invention.

In the present invention, the blending ratio of organic polyisocyanate and polyoxyalkylene polyol is 0.00 parts per 100 parts of the polyisocyanate compound (in the present invention, parts indicate parts by weight).
In order to react the organic polyisocyanate, which is preferably in the range of 5 to 10 parts, particularly preferably in the range of 1 to 5 parts, and the polyoxyalkylene polyol, it is heated at 70 to 80°C for 1 to 2 hours. The obtained polyisocyanate composition has a viscosity of 80 to
It is a liquid with a temperature of 600 cps/25°C and an isocyanate content of 20 to 35% by weight.

When applying these polyisocyanate compositions to the inner surface of core paper and/or liner paper, they can be applied as is, or they can be applied after being dissolved in a solvent. Solvents can be used. For example, methylene chloride, ethyl acetate, hexane, selonlupe acetate, etc. are used.

When applying the polyisocyanate composition of the present invention to the inner surface of core paper and/or liner paper, colorants, fillers, organic acids, known curing accelerators for urethane, etc. can also be added.

The amount of the polyincyanate composition of the present invention to be applied is not particularly limited and is appropriately determined depending on the use, effectiveness, etc. solvent-based)
is preferred. Further, whether to use the polyisocyanate composition as a coating liquid as it is or as a solution is appropriately determined depending on the coating amount, coating method, coating position on the line, etc.

Suitable adhesives containing active hydrogen used in the present invention include starches such as corn and wheat, dextrin, polyvinyl alcohol, carboxymethyl cellulose, casein, etc., used alone or in combination of two or more in several times the amount. It is made by kneading it with water to make a viscous liquid.

Among these adhesives, those having alkalinity have high reactivity with polyisocyanates and can be used as they are, and adhesives using corn starch are particularly preferred because they are inexpensive.

The polyisocyanate composition of the present invention can be applied at any position on the line of known corrugated board manufacturing equipment (so-called corrugating machine) currently widely used in the industry.

In the present invention, the application points are the core paper (2 sides) and the inner surface of the thinner paper (2 sides) for double-sided cardboard, and the core paper (2 sides) and the inner surface of the liner paper (1 side) for single-sided cardboard. ) (also simply referred to as the inner surface of the core paper and/or liner paper). The coating may be applied to all six sides of the container, to the body (four sides), or any other area depending on the purpose of the container.

The manufacturing method of the container of the present invention will be explained with reference to FIG. 1, taking double-sided cardboard as an example. This also applies to single-sided cardboard. Application of the polyincyanate composition is carried out during the period from (5) supply stock 1 of the corrugated paper until it enters the stepped roll 2.
(B) For gluing, the single-sided cardboard 7 that has come out of the adhesive roll 6 that adheres the corrugated core paper that has come out of the roll 3 and the liner paper 5 from the liner paper supply stock 4 is transferred to the roll 8 for the next gluing. (C) The single-sided cardboard with adhesive applied to the top of the corrugation exits the gluing roll 8 and is bonded to liner paper 10 from another liner paper supply stock 9. You can do it anywhere up to roll 11. That is, the coating can be applied anywhere on the line where the core paper is not used.

As the coating method, any known method can be selected, but in the case of the coating position (A), the roll coating method is preferable;
) or (C), a spray coating method is advantageous.

The polyisocyanate composition applied to the inner surface of the core paper and/or liner paper by the manufacturing method of the present invention immediately penetrates between and within the fibers of the paper, and the polyisocyanate composition on the coated surface is applied to the inner surface of the core paper and/or liner paper. Or, it is adsorbed and dispersed to the inner surface of the liner paper. At this time, the starch-based adhesive is applied while the curing reaction of the polyisocyanate composition is still little to no progress, or the adhesive is applied first, and the polyisocyanate composition is applied while the adhesive is uncured. apply something.

In the present invention, "uncured" refers to a state in which the curing reaction does not occur or the curing reaction is slightly progressing but the curing is not completed.

The polyisocyanate composition used in the present invention is easily adsorbed from the inner surface of the core paper and/or liner paper, where the hydroxyl groups and incyanate groups of the weakly alkaline starch that constitute the adhesive react. Strengthens the adhesion between the core paper and the inner surface of the liner paper.

10- The polyisocyanate composition used in the present invention is easily adsorbed from the inner surface of the core paper and/or liner paper, where the hydroxyl groups of the weakly alkaline starch constituting the adhesive react with the incyanate groups. to strengthen the adhesion between the core paper and the inner surface of the liner paper.

Next, the remaining incyanate groups react with the hydroxyl groups of Cellulose It gradually reacts with the moisture contained in it and the moisture in the air to form a resin, creating a strong cross-linking effect between the fibers.

Therefore, compared to known reinforcing agents, even by applying a small amount, the compressive strength of the cardboard is significantly increased, and at the same time, water-resistant adhesion between the liner paper and the core paper is imparted, which is unimaginable with conventional known methods. effect occurs.

As a result, corrugated cardboard can be manufactured without any problems even if a commonly used starch adhesive is used, without using any special equipment such as drying or curing as in conventionally known strengthening treatment methods. Corrugated cardboard manufactured by applying a polyisocyanate composition to the inner surface of the core paper and/or liner paper in this way reacts sufficiently with the adhesive even immediately after manufacture, and the adhesive surface may peel off. Although this is not the case, the polyisocyanate composition applied to other parts has hardly reacted yet and has not been turned into a resin.

Therefore, immediately after manufacturing, the cardboard has not yet developed its strength.
In fact, the hardness may be slightly lower than that of the uncoated one. Therefore, a major feature of the present invention is that the work of inserting and cutting the wire can be done easily, and there is no problem in the box manufacturing work.

The unreacted incyanate groups gradually react with the hydroxyl groups of cellulose constituting the inner surface of the core paper and/or liner paper, the moisture contained in the inner surface of the core paper and/or liner paper, and the moisture in the atmosphere. Then, urea and urethane bonding progresses to form a resin.

It usually takes 5 to 7 days for the polyisocyanate composition to fully develop its strength.

With the polyisocyanate composition of the present invention, core paper and/or
Or, because the inner surface of the liner paper is physically and chemically strengthened, the manufactured cardboard has sufficient stiffness and is not brittle at all even after complete hardening. Therefore, the present invention will be specifically described below with reference to examples, in which the cardboard container can be handled in the same manner as conventional cardboard containers during assembly work.

A typical example is 220 (
A method for producing double-sided corrugated cardboard (A-flute) having a base paper structure of 220 (liner paper) and 25 (core paper) will be described.

A starch paste having the following composition was used as the adhesive.

Water 100 parts Corn starch 30' Borax 0.51 50% caustic soda aqueous solution 2.51 Reference Example 1 Polyoxyethylene polyoxypropylene diol with an OH value of 72 was obtained by addition polymerizing ethylene oxide 13- and propylene oxide to diethylene glycol. Ta. Convert 3 parts of this diol into polymethylene polyphenylene
Polyisocyanate (Mitsui Nisso') L/Tough MDI-
Mix with 100 parts of CR200) and heat at 80°C in a nitrogen stream.
After a heating reaction for 2 hours, the mixture was cooled to obtain a modified polyinsyanate composition containing 29% NGO.

Example 1 5 parts of polymethylene polyphenylene polyisocyanate (MDI-CR200 manufactured by Mitsui Nisso Urethane Co., Ltd.) (the same applies hereinafter) was thoroughly mixed and dissolved with 5 parts of methylene chloride.
A 0% by weight solution was made.

Apply this solution to a roll coater using core paper (SCP125).
) on the negative side of
After passing through a preheater roll at 50℃, step forming (
The corrugated core paper was then coated with a polyincyanate composition of 1 s rim", and was adhered to two sheets of liner paper (K220) using starch glue to make a double-sided cardboard.

After being left at room temperature for 24 hours, a box was formed. After leaving this at room temperature for another 7 days, a cardboard container was assembled.

After this cardboard container was left at 20°C and 65XRH for 24 hours, the physical properties were measured and the results were as shown in Table 1 and Example 1.

Example 2 Starch glue was applied to the corrugated top of a single-sided cardboard made of untreated core paper and liner paper. Apply a solution of polymethylene polyphenylene polyisocyanate composition to the center core side on one side of a cardboard box (m2/F) 30? (As a solvent-free base,
After spraying 20t), liner paper was adhered to make double-sided cardboard.

After this double-sided cardboard was treated in the same manner as in Example 1, the physical properties were measured and the results were as shown in Table 1 and Example 2.

Example 3 Double-sided corrugated cardboard was obtained in exactly the same manner as in Example 1, except that polymethylene polyphenylene polyisocyanate was applied with a roll coater at 20 f per X m2 of core paper (30 r/m'' for stepped core paper). Ta.

After this double-sided cardboard was treated in the same manner as in Example 1, the physical properties were measured and the results were as shown in Table 1 and Example 3.

In addition, the results of immersing cardboard that had been left at room temperature for 7 days in water at room temperature for 24 hours showed that the adhesion between the polyisocyanate composition-coated surface of the core paper and the liner paper was maintained, and the flute of the core paper remained intact. No change in shape was observed.

Comparative Example 1 In Example 1, a double-sided cardboard was made without applying the solution of the polymethylene polyphenylene polyinsyanate composition to the core paper.

After this double-sided cardboard was treated in the same manner as in Example 1, the physical properties were measured and the results were as shown in Table 1 and Comparative Example 1.

When this cardboard was left at room temperature for 7 days and then immersed in water at room temperature for 1 hour, the liner paper and core paper separated in the water and the flute shape also collapsed.

Example 4 The area where the polymethylene polyphenylene polyinsyanate composition was applied was coated with liner paper (K220) (
(Applied between supply stock 4 and adhesive roll 6 in Figure 1)
Other than that, a reinforced cardboard container was assembled in exactly the same manner as in Example 1.

The physical properties of this reinforced cardboard container were measured in the same manner as in Example 1, and the results were as shown in Table 2 and Example 4.

Example 5 The polymethylene polyphenylene polyisocyanate composition was applied to the same core paper as in Example 1, and the polymethylene polyphenylene polyisocyanate composition was also applied to liner paper (K220) in the same manner (the liner shown in Figure 1). (applied between paper supply stock 4 and adhesive roll 6)
. Otherwise, the construction was carried out in exactly the same manner as in Example 1, and a reinforced cardboard container was assembled.

17 - The physical properties of this reinforced cardboard container were measured in the same manner as in Example 1, and the results were as shown in Table 2, Example 5.

As shown in Tables 1 and 2, it is clear that the strength of cardboard and cardboard containers by the method of the present invention is significantly enhanced.

Example 6 In Example 3, a double-sided cardboard was obtained in exactly the same manner as in Example 3, except that the modified polyisocyanate composition obtained in Reference Example 1 was used instead of the polymethylene polyphenylene polyisocyanate.

The physical properties of this cardboard and a reinforced cardboard container using the same were as follows.

Vertical compressive strength (Note 2) 7.83 kgf/cm Planar compressive strength (Note 2) 2, 20 kgf/cm'' Adhesive strength (bottle strength) (Note 3) 28.3 kgf Box compressive strength (Note 4) 388 kgf ( Note 2) to (Note 4): See Table 1

[Brief explanation of the drawing]

FIG. 1 shows a production line for double-sided corrugated cardboard according to the present invention. In Figure 1, 1 is a supply stock of core paper, 2 is a roll for corrugating, 3 is a roll for gluing, 4 is a supply stock of liner paper, 5 is liner paper, 6 is an expanded adhesive roll, 7 is single-sided corrugated cardboard , 8 is a roll for gluing, 9 is another liner paper supply stock, 10 is liner paper, and 11 is an adhesive roll for bonding the single-sided cardboard and the liner paper. Patent applicant Mitsui Nisso Urethane Co., Ltd. 21-

Claims (2)

[Claims] (1) A polyisocyanate composition or a solution thereof was applied to at least one of the inner surfaces of the core paper and the liner paper, and the uncured polyisocyanate composition and the top of the corrugated core paper were coated. A strong 91 cylindrical porcelain ball made by bonding the corrugated top portion of the core paper and the liner paper using an uncured adhesive containing active hydrogen. (2) A small amount of the inner surface of the core paper and the liner paper is coated with an uncured adhesive containing active hydrogen applied to the top of the corrugation of the core paper, and the corrugation of the core paper is applied.