JPH0560420B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing a double-sided plastic corrugated board.

[Conventional technology]

Compared to paper cardboard, plastic corrugated boards have many other advantages, such as being stronger, resistant to water and moisture, and being easily molded into the desired shape using vacuum forming and other forming methods. It is used as a substitute for various packaging materials, and as a substrate material for lightweight composite boards (laminates) for various uses such as vehicle interior materials and building materials.

Basically, a liner sheet is pasted on only one side of a core sheet whose sheet surface has been subjected to uneven molding.
There is a so-called single-sided corrugated board with a layered structure, and a so-called double-sided corrugated board with a three-layer structure in which liner sheets are laminated on both sides of a core sheet.

The present invention particularly relates to a method for manufacturing a double-sided corrugated board. Conventionally, double-sided corrugated cardboard boards have generally been industrially mass-produced continuously in the following manner.

(1) First step (molding of core sheet) A sheet of thermoplastic material in a molten state is continuously sheeted out using a first extruder, etc., and is rotated or rotationally driven at a predetermined speed. Vacuum forming roll (Japanese Patent Application Laid-Open No. 58-108113
(Japanese Patent Publication No. 60-49106, etc.) or a vacuum forming belt (Japanese Patent Publication No. 52-40666) to form numerous cylindrical, prismatic, and hemispherical shapes over almost the entire sheet surface.・Concave and convex portions such as lattice shapes and corrugations are sequentially formed to form a concavo-convex core sheet.

(2) Second step (lamination of the first liner sheet) The free surface of the textured core sheet on which the textured portion is formed and moves in close contact with the rotating roll surface or the rotating belt surface. On the side, a thermoplastic material sheet in a molten state as a first liner sheet, which is continuously sheeted out by a second extruder or the like, is continuously supplied and pressed to be bonded together. The integrally laminated body of the core sheet and the first liner sheet is cooled and hardened to a predetermined temperature using a cooling means, and is sequentially taken out from the rotary roll surface or the rotary belt surface and released from the mold.

(3) Third step (laminating the second liner sheet) Opposite to the first liner sheet pasting side of the textured core sheet, which is successively released from the rotary roll surface or rotary belt surface. On the side surface, a sheet of thermoplastic material as a second liner sheet in a molten state is continuously fed by a third extruder or the like.
Press and paste together. The bonded second liner sheet is cooled and hardened by a cooling means.

As a result, a three-layer plastic double-sided corrugated board with a textured core sheet inside and liner sheets laminated on both sides of the core sheet is continuously produced (if no second liner sheet is laminated). single-sided corrugated boards are produced continuously).

[Problem that the invention seeks to solve]

In reality, the plastic double-sided corrugated board manufactured in the manner described above exhibits warping to a greater or lesser degree toward the side to which the second liner sheet is bonded. The warpage cannot be completely removed even if the double-sided corrugated board is subsequently annealed (reheated). For this reason, strict flatness (smoothness) is required, such as building materials such as wall materials and ceiling materials, floor covering materials for automobile trucks, etc.
When used as a constituent material for packaging cases and the like, the above-mentioned warpage often poses a problem.

The cause of the warpage described above is considered as follows. That is, through the first and second steps described above, the rotating roll surface or rotating belt surface is sequentially cooled and cooled.
The integrally bonded body of the core sheet and first liner sheet that is released from the mold has already substantially completed shrinkage due to internal strain force at the time of release. Next, a sheet in a molten state as a second liner sheet is laminated to the surface of the release core sheet opposite to the side to which the first liner sheet is laminated, and the sheet contracts due to the force of internal distortion as it cools. However, at this time, the integrally laminated body of the core sheet and the first liner sheet does not substantially shrink, so that the shrinkage force of the second liner sheet is applied in the plane direction of the core sheet to which the second liner sheet is laminated. As a result, the entire double-sided corrugated board produced is thought to be warped to a greater or lesser extent toward the surface to which the second liner sheet is bonded.

Even if the double-sided corrugated board is subsequently annealed to remove residual internal distortion, the core sheet and the first liner sheet are integrally laminated,
It is thought that the residual internal distortion forces between the two and the second liner sheet that was laminated later are already unbalanced, so that the warpage cannot be substantially corrected and removed.

The object of the present invention is to mass-produce double-sided plastic corrugated cardboard boards that are substantially free from warping and have good flatness.

B. Structure of the Invention [Means for Solving the Problems] The present invention provides for substantially simultaneously sandwiching both sides of a core sheet of a thermoplastic material that has been continuously fed out with concave and convex shapes. Production of a double-sided plastic corrugated board, characterized in that sheets of thermoplastic plastic material in a melted or thermally softened state are continuously supplied and bonded together as first and second liner sheets so that the first and second liner sheets are tightly bonded together. The method is summarized.

[Effect]

When a double-sided plastic corrugated board is manufactured in the manner described above, it is actually a continuously stable sheet with good flatness as a whole with virtually no warping on either side of the first or second liner sheet. It was mass-produced in

This means that the first and second sheets in a melted or softened state are laminated on both sides of the core sheet almost simultaneously.
It is thought that this is because the liner sheets shrink in substantially the same state when they are cooled simultaneously, and the liner sheets harden in a state in which the balance of the shrinkage forces of both sheets is maintained substantially evenly.

〔Example〕

FIG. 1 is a schematic diagram of a manufacturing line of one embodiment.

Reference numeral 3 denotes an endless type belt suspended between a pair of parallel rollers 1 and 2, and is continuously driven to rotate at a predetermined circumferential speed in the direction of the arrow. As shown in the partially enlarged sectional view of FIG. 2, this type belt 3 is a two-layer structure consisting of a heat-resistant rubber belt 31 and a stainless steel belt 32 that is integrally bonded to the outer circumferential surface of the heat-resistant rubber belt 31. - A large number of through-holes are formed with a planar shape, arrangement, and density, and a thin stainless steel tube 33 is fitted into each of the through-holes to prevent them from coming off. Specifically, in this embodiment, the heat-resistant rubber belt 31-
Thickness 4.0mm, stainless steel belt 32-thickness 0.5mm,
Through hole - circular hole with inner diameter of 8.8 mm, stainless steel tube 3
3-The wall thickness is set to 0.4 mm, the inner diameter is 8 mm, and the length is approximately 4.5 mm.

4 is three parallel rollers 41, 42, 43 between the rollers 1 and 2 on which the mold belt 3 is stretched and stretched.
It is an endless stainless steel wire mesh belt that is suspended and stretched between the belts, and is in contact with the lower surface of the upper belt part of the mold belt 3, and rotates at the circumferential speed that is synchronized with the rotating speed of the mold belt 3. It is continuously rotated in the direction. Reference numeral 44 denotes a brush for cleaning the stainless steel wire mesh belt, which is disposed in contact with the belt.

5 is a vacuum suction duct (vacuum zone) disposed inside the stainless steel wire mesh belt 4 with its suction opening facing upward. Therefore, during the rotation process of the mold belt 3, the air in each stainless steel cylinder 33 existing in the mold belt portion area passing through the duct 5 is sucked through the holes of the stainless wire mesh 4, and the mold belt 3 is brought into a vacuum suction state.

Reference numeral 6 denotes a mold belt cooling device disposed at the lower belt portion of the mold belt 3. In this example, a metal nonwoven fabric (metal wool) 62 with a roughness (density) that does not absorb water due to capillary phenomenon is placed in a pan 61 through which cooling water is circulated.
The upper surface of the water-cooled nonwoven fabric is always in contact with the lower surface of the lower belt portion of the mold belt 3 to cool the mold belt 3, and a cold air duct 63 is installed in parallel to cool the nonwoven fabric. It is designed to cool down by spraying it with water.

7 is a sheeting nozzle die of the first extruder, which is not shown in the figure, and is located above the upper belt part of the mold belt 3, and the molten thermoplastic plastic material sheet A' for the core sheet is continuously produced. It is extruded and discharged. The discharged sheet A' is continuously supplied to the upper surface of the upper belt portion of the mold belt 3 which is in a rotationally driven state, is pressed by the pressure roller 8, and passes through the vacuum zone region where the vacuum suction duct 5 is arranged. In the process, the sheet portion corresponding to each stainless steel tube 33, which is a concave portion on the surface of the mold belt 3, is vacuum-suction molded into the cylinder (Fig. 2), thereby creating an uneven shape corresponding to the perforated belt surface. Core sheets A are continuously manufactured.

During the time from the vacuum zone area 5 to the mold release position 9, the uneven molded core sheet A is heat removed by the mold belt 3 and becomes a cooled and hardened state where it can be released from the mold.
The mold is sequentially released from the three sides of the mold belt.

10 is a sheeting nozzle die of a second extruder (not shown) located above the upper surface of the core sheet next to the core sheet conveying direction of the mold belt 3; A sheet of thermoplastic material B' in a molten state is continuously extruded and discharged. The discharged sheet B' is released from the surface of the mold belt 3, is continuously supplied to the upper surface of the core sheet A which is being conveyed, and is pressed and bonded by the pressure roller 11.

12 is the sheeting nozzle die of the third extruder (not shown in the figure), which is located on the opposite side of the sheeting nozzle die of the second extruder with the core sheet A inside; A thermoplastic core sheet C' in a molten state as a two-liner sheet C is continuously extruded and discharged. The discharged sheet C' is released from the surface of the mold belt 3, is continuously supplied to the lower surface of the core sheet A which is being conveyed, and is pressed and bonded by the pressure roller 13.

In this case, the pressure roller 11 of the first liner sheet B
The pressure rollers 13 of the second liner sheet C are disposed substantially opposite to each other on the upper and lower surfaces of the core sheet A, and therefore the first liner sheet B,
B' and the second liner sheets C and C' are supplied and applied to both sides of the core sheet A so as to sandwich the core sheet substantially simultaneously, and are continuously and simultaneously laminated. FIG. 3 shows a partial perspective view of the pressure rollers 11 and 13.

It passed between the pressure rollers 11 and 13. The three-layer laminated body of the core sheet A, the first and second liner sheets B and C, that is, the double-sided corrugated board, then passes through a cooling unit 14 such as an air cooling type, and the first and second liner sheets B, C is cooled and hardened.

The double-sided corrugated board as a product that has passed through the cooling means section 14 is rolled up or automatically cut into regular length cut boards.

As mentioned above, the first
liner sheets A, A' and second liner sheet B,
The double-sided corrugated board obtained by laminating B' at the same time and cooling it is substantially free of warpage and has good flatness, as described in the section of the above-mentioned function. Even if there is some warping or curling due to winding,
It is also possible to remove it by annealing.

In the embodiments described above, the mold belt 3 can also be a rotating roll. The sheets for the core, the first liner, and the second liner can be manufactured continuously using an extruder, or they can be manufactured using a heating means such as a heating furnace using long sheets of thermoplastic material that have been manufactured and stored in advance. The thermoplastic material sheet is continuously made into a sufficiently thermally softened or molten state by heating, or the sheet of thermoplastic material is continuously manufactured using a sheeting device such as a calender roll, and then the sheet is additionally heated through a heating furnace or the like to be sufficiently thermally softened. It can also be used in a state or a molten state.

In addition, each sheet is made of, for example, heat-resistant resin such as polypropylene resin, polyethylene resin, E/V/A resin, T/P/E resin, etc., with or without an appropriate amount of filler such as talc and calcium carbonate. It is a sheet of plastic material, about 0.1 to 2 mm thick, soft, semi-hard, hard, solid, or with low foaming. Each sheet may be of the same kind or of different kinds. The first liner sheets B, B' and/or the second liner sheets C, C' may be laminated to the core sheet A by using an appropriate adhesive as necessary. .

At the same time as the first and second liner sheets are laminated to the core sheet, another sheet material layer D (e.g. woven fabric, knitted fabric, non-woven fabric, paper, plastic sheet) is applied to the outer surface of the first and/or second liner sheet. Exterior materials and/or backing materials such as synthetic leather, natural leather, rubber sheets, carpet materials, etc.) can also be bonded together by thermocompression bonding or by using an adhesive.

FIG. 4 shows another embodiment, in which the first and second liner sheets B and C are simultaneously attached to both sides of the core sheet A using a two-layer co-extrusion molding die 40 made of thermoplastic sheets. It was designed to match.

The core sheet A is introduced from the rear end of the die into a flat gap passageway 41 that penetrates the center of the die 40 in the front-rear direction, and is continuously fed forward from the tip of the die at a predetermined speed. . In the process of the core sheet A coming out from the tip of the die, its upper and lower surfaces are extruded from the upper lip part 42 and the lower lip part 43 at the same extrusion speed as the feeding speed of the core sheet A and with a predetermined thickness. A thermoplastic sheet B' serving as the first liner sheet B and a thermoplastic sheet C' serving as the second liner sheet C are sequentially laminated at the same time. Next, this three layer B,
The laminated bodies A and C are introduced into a cooling device through a pair of pressing rollers provided as necessary, and then
The second liner sheets B and C are cooled and hardened.

In FIG. 4, reference numeral 44 denotes external dies 45 and 46 that constitute the outer shell of the two-layer coextrusion molding die 40.
denotes first and second movable angle-adjustable dies arranged vertically within the external die, and 51 and 52 denote the tips of the first and second extruders to which the die 40 is attached. By varying the type, color, etc. of plastic introduced into the die 40 from the first and second extruders 51, 52, the materials, colors, etc. of the first and second liner sheets B, C can be made different as desired. A double-sided corrugated board in the form of a paperboard is produced.

C. Effects of the Invention As described above, according to the present invention, it is possible to easily mass-produce double-sided plastic corrugated cardboard boards with good flatness (smoothness) without substantially warping, and It can be used without any problem as building materials such as wall materials and ceiling materials, and other structural materials where properties are required, and the intended purpose is well achieved.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a production line of one embodiment, Fig. 2 is a partially enlarged cross-sectional view of a mold belt, Fig. 3 is a partial oblique view of the pressure roller portion of the first and second liner sheets, and Fig. 4 1 is a cross-sectional view of a two-layer co-extrusion molding die in a state in which first and second liner sheets are simultaneously laminated to a core sheet. 3 is an endless rotating belt; 7, 10, and 12 are sheeting nozzle dies of the first, second, and third extruders, respectively; 8, 11, and 13 are sheet pressure rollers;
1 is a textured core sheet, B, B', C, and C' are first and second liner sheets, and D is another simultaneously laminated sheet material.

Claims (1)

[Claims] 1 Melting or thermal softening of the first and second liner sheets on both sides of the core sheet of thermoplastic material which is continuously fed out and which has been formed with concave and convex shapes, so as to sandwich the core sheet almost simultaneously. A method for producing a double-sided plastic corrugated board, characterized by continuously supplying, pressing and bonding sheets of thermoplastic plastic material.