JPS58212935A - Corrugated cardboard sheet and its manufacture - 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 a corrugated cardboard sheet with a plastic film liner that is inexpensive and has excellent water resistance, and a method for producing the same.

Ordinary corrugated cardboard sheets are lightweight and inexpensive, and have appropriate strength, cushioning properties, and heat insulation properties, and are therefore widely used as materials for boxes and the like for packaging various products.

However, ordinary corrugated cardboard has the disadvantage that the liner is made of paper such as kraft paper and the adhesive to the core is starch glue, so it is not water resistant and its strength is extremely reduced due to moisture absorption. For this reason, the inventor has conducted extensive research in order to form a water-resistant layer on the outer layer of the liner, and has developed and provided a water-resistant corrugated board in which a plastic film layer is entirely formed on the outer layer of a paper liner, and a method for manufacturing the same.

Conventionally, it has been difficult to use plastic film in any form as a component of corrugated paperboard sheets in corrugating machines. This is because it has been difficult to stably produce products that are heat resistant and do not warp during the heating process. The present inventor has endeavored to solve all of these problems and has developed the above-mentioned water-resistant membrane ball.

However, it cannot be denied that configuring a plastic film layer on the surface of a single layer of conventional paper liner increases the amount of waste material and increases the cost.

Further, still using starch paste as an adhesive is a disadvantage in terms of water resistance, while using a water resistant adhesive causes higher costs.

The inventor of the present invention has been conducting research in order to provide a corrugated board with excellent water resistance at a low cost. We succeeded in manufacturing a corrugated board sheet consisting of a liner with only a plastic film layer removed.

In other words, the corrugated board of the present invention (fiyV-) has a plastic film made of a heat-fusible resin with a low melting point on one or both sides of the core, which is corrugated using the heat-fusibility of the inside surface. It is characterized by being made by adhering a plastic film as a single liner.

In addition, the manufacturing method involves bonding the above-mentioned plastic film as a single back liner to the other corrugated top of the center core of a single-sided corrugated cardboard in the heating section of a part of the double facer of a corrugating machine, using the heat weldability of its inner surface. In this case, a buffer film is interposed between the plastic film and the hot plate of the heating section in the form of an endless belt.

In this way, the present invention maintains the characteristics of conventional corrugated poles by using a corrugated core, eliminates the need for adhesive by skillfully utilizing heat-fusible resin, and furthermore maintains its shape as a liner. By constructing the corrugated pole sheet with the obtained plastic film, the paper layer from the conventional liner is eliminated, and a corrugated pole sheet with excellent water resistance and workability is provided at low cost.

This allows the product to be used in areas where conventional water-resistant corrugated cardboard could not be used.

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a perspective cross-sectional view showing the structure of a corrugated cardboard sheet 1 according to one embodiment of the present invention, which is composed of a corrugated paper core 2 and a film liner 3.3 made of only plastic films on the front and back sides. .

Moreover, this film liner 3 is a heat-fusible film 3
A is used as an inner layer (center core 2911), and a stretched reinforced film 3b with excellent mechanical properties is used as an outer layer.

The most typical example of the heat-fusible film 3a is a low melting point polyethylene film or an ethylene copolymer film that is easily heat-cured. This portion 8 is heated and melted by heat conduction, and the stepped top portion of the core 2 contacts and pressurizes it and joins each other.

As the stretched reinforced film 3b, a uniaxially or biaxially stretched polypropylene film is most commonly used. This stretched reinforced film 3b is a reinforcing base material laminated to the heat-welded film 3a in order to maintain the shape of the liner 3, and even after the step top of the core 2 and the heat-welded film 3a are heat-pressed, this stretched and reinforced film 3b is The reinforcing film 3b allows the liner 3 to maintain its normal shape.

In general, polyester films and biaxially oriented polypropylene films are difficult to thermally bond, especially heat S/-, A/, so polyethylene films with low heat resistance and capable of heat-sealing/L/L are laminated and thermally bonded (heat S/-). /I/) is commercially available as a so-called fuminate film. In this example, this fuminate film can be used as the film liner 3.

Alternatively, for example, a polyethylene raw material may be heated and melted in an extruder, extruded into a film having a constant thickness, laminated on the stretched reinforced polypropylene film 3b, and simultaneously welded to the top of the step of the core 2.

In addition, in the above embodiment, the film liner 3 is formed by laminating the thermofusible film 3a with the stretched reinforced film 3b as the plastic base material. However, the plastic base material is not necessarily limited to the stretched reinforced film. In short, any planutic film that has a high melting point and is difficult to thermally bond will suffice. Therefore, for example, polyester film, cellophane, acetate film, etc. can also be used as the base material for laminating the heat-fusible film 3a.

゛ In this way, in the corrugated board sheet of the present invention, the film itself constituting the liner 3 is bonded to the core 2 due to its thermal weldability.
Since it is directly glued to the top of the tier, it can be used with starch glue used with regular tiered poles or holatome A used with conventional water-resistant cardboard.
/) agent or water-resistant adhesive is not required at all.

FIG. 2 shows an embodiment in which the film liner 3 is not a laminate film as shown in FIG. 1, but is composed of a slightly thick heat-weldable polyethylene film 3a alone. In this way, according to the heat-fusible film 3a having a nominal thickness, it can be bonded to the step top of the core 2 under heating conditions that melt only the inner surface side, and it can also maintain its shape as a liner. can. Note that the other liner 4 is a normal paper liner.

In this example, since there is a large difference in heat shrinkage rate between the film liner 3 and the paper liner 4, the film liner 3 tends to warp greatly. However, if this property is utilized, wrapping is suitable for wrapping highly hygroscopic products by wrapping them on the film liner 3 side.

Fig. 3 shows another example, in which the plastic reinforcement material for the outer layer is a cloth made by plain weaving flat yarns ([naka tape) or split yarns of medium-low pressure polyethylene film or polypropylene film] or by laminating them vertically and horizontally. It uses a nonwoven fabric obtained by adhesion.

The film liner is made by using the loss 5 or nonwoven fabric as a base material and laminating the heat-welding film 3a thereon.
3 is much superior to the laminate film finisher shown in FIG. 1 in terms of mechanical strength such as bursting strength and tearing strength, so it can be used in the field of fishing boxes, which were conventionally made of wood.

Note that in all of the above examples, heat weldability is imparted by a heat weldable film, but the imparting of heat and illumination to the base film is not limited to the above examples; The same effect can also be achieved by coating with a coating resin such as a copolymer or styrene-butadiene rubber.

It is something that can exhibit effects.

FIG. 4 is a configuration diagram of an embodiment of the apparatus for manufacturing the corrugated pole sheet 1 of the present invention, but compared to the conventional corrugating machine, there is no need for an adhesive such as starch glue or an adhesive device used. The difference is that the double facer has a one-sided band sealer that uses an endless belt in the heating section of a part of the double facer.

That is, the paper core base paper 2a is heated with a preheater and then placed between the row rows /l/6 and 6, and the laminate film 3c for the front liner, which has a heat-fusible film laminated on the inner surface, is in an unheated state. It enters from the lower part of the press 'q-iv7, and one corrugated top of the core 2 and the heat-welding film are combined and shivered, and at the same time, heat-welded to form a single-sided corrugated board/I/8-.

In this instant bonding process using the stage roll/I/6 and press roll lv7, the heating to melt the heat-welding film is performed by the stage roll/I/6 and the press roll lv7.
Since the press roll/I/7 applied from the 1/6 side is not heated, the reinforcing film of the outer layer hardly changes.

The heating section 9 of some double phasers has the above-mentioned single-sided corrugated board)
L/8 is sent in immediately. At the same time, the laminate film 3d for the back liner is fed into the upper heating section 9 in order to thermally weld its heat-sealable film layer to the top of the other corrugated board of the single-sided corrugated board/I/8.

In this heating section 9, the corrugated roll 6 and the pressed crystal-A/7
Unlike instant heat-pressure bonding, the contact pressure between the core and the heat-sealable film is relaxed to the extent that it does not crush the core, so the heat-sealing of the heat-sealable film on the hot plate takes time. It is done.

Further, since heating is applied by the hot plate 10 on which the laminate film 3d is placed, the outer layer of the laminate film, that is, the film reinforcing base material, which needs to maintain the liner shape, must be protected from the heating of the hot plate 10.

In the present invention, a buffer ill is interposed between the laminate film 3d and the hot plate 10 in the form of an endless belt to protect the film reinforcing base material from the hot plate 10 and to appropriately conduct molten heat to the heat welding film. are doing. Furthermore, the buffer film 11 is constructed in the shape of an endless belt for economical use, and the corrugated cardboard sheet 1 is transported smoothly by utilizing the appropriate frictional resistance on the surface of the buffer film 11.

As the buffer film 11, a material having a high melting temperature, excellent strength, excessive thermal conductivity, and an appropriate thickness is used. The simplest method is to form an endless belt out of kraft paper or ordinary corrugated paper. However, preferably, the roller 13 for the belt 12 shown in the figure is formed into an endless belt using a heat-resistant film such as Teflon or a sheet of heat-resistant inorganic fiber whose surface has been treated with Teflon as a buffer film. An idle loaf or a driven loaf is used depending on the degree of friction. The temperature of the hot plate 10 is P/
The material, thickness, moving speed, etc. of the pel 12 are determined so that the heat conducted through the pel 12 heats and melts only the inner heat-sealing film.

The corrugated board IL/V-t 1 in the heating section 9 is pressed against the endless belt 12 by the corrugating belt 14, and in the process of being conveyed together with the belt 12, the amount of heat required for thermal welding of the front film liner and the core is increased. is received from the hot plate 10.

If the buffer film 11 of the endless board 12 is not provided, the heating plate 10-F of the corrugated cardboard sheet 1-1 would be
There is no movement, and if there is even a slight movement, the outer film will rub against the two sides of the hot plate and be damaged.

The buffer film 11 prevents this and also relieves the heat from the hot plate 10 and transmits it to the front liner, thereby preventing the outer layer film of the front liner from melting. Moreover, while passing over the hot plate, the temperature and time are given to melt the inner heat-sealable film. By taking this time appropriately, melt bonding can be completed at an appropriate temperature.

In the heating section 9, the corrugated pole sheet 1 which has completed adhesion between the core and the back side film liner passes through the next cooling section 15 and is cut into predetermined dimensions by a cutter 16.

The corrugated board of the present invention manufactured in this way has a liner made of only plastic film and a base, and is also bonded to the core using a heat-fusible resin, so it can be used for packaging products that require water resistance, such as fishing boxes. It can also be used as

In addition, because paper materials and adhesives are rationalized in this film liner, it can be manufactured at a lower cost than ordinary corrugated poles.

As described above, the corrugated board of the present invention expands the uses of corrugated paperboards and is extremely useful for reducing conuts.

The core shown in the above embodiments was made of paper alone, but the core may be made of a plastic sheet or film laminated with paper on both sides, or a 10-thick plastic sheet made of paper. By configuring this, the water resistance of the corrugated cardboard sheet of the present invention can be further improved, and a so-called completely waterproof packaging material can be provided.

[Brief explanation of the drawing]

1 to 3 are respectively perspective sectional views showing the structure of a corrugated pole sheet according to an embodiment of the present invention, and FIG. 4 is a configuration diagram of an embodiment of an apparatus for manufacturing the same corrugated board sheet.

Claims (1)

[Claims] 1) Utilizing the heat-fusibility of a plastic film whose at least the inner surface is made of a heat-fusibility resin with a low melting point,
A corrugated pole sheet made by adhering the plastic film alone to one or both sides of a corrugated core as a plastic film liner. 2) The corrugated board sheet according to claim (1), wherein the plastic film is a laminate film made of a stretched reinforced film as a base material and a heat-fusible film laminated thereon. 3) In the heating section of a double facer of a corrugating machine, at least the inner surface of the plastic film is made of a heat-fusible resin with a low melting point. A method for manufacturing a corrugated board sheet, characterized in that when a back liner of a plastic film alone is attached to the top and bonded to the top, a buffer film is interposed in the shape of an endless belt between the plastic film and the heating plate of the heating section.