JP2015066891A - Sizing apparatus for hollow plastic sheet, and manufacturing method of hollow plastic sheet using the same - Google Patents

Abstract

Provided are a sizing device for a hollow plastic sheet and a method for producing a hollow plastic sheet using the device, which can perform more efficient cooling uniformly in the width direction of the sheet when manufacturing the hollow plastic sheet.
A first decompression section 10 comprising a water supply / drainage block 20 of a first sizing plate 2 in contact with a melt-extruded hollow plastic sheet has a water supply groove 5G opposed to the water supply slit 5 and connected to the water supply means. A drainage groove 4G facing the drainage slit 4 and connected to the drainage means is disposed, and the water supply groove 5G is divided into a plurality of water supplies in order to supply water uniformly in the width direction of the plate according to the width dimension of the hollow plastic sheet The drainage groove 4G is provided with drainage means for draining uniformly in the width direction of the plate, and further, a second decompression section having the same configuration is connected to the take-up side. A sizing device for a hollow plastic sheet, and a method for producing a hollow plastic sheet using the device.
[Selection] Figure 2

Description

  The present invention relates to a sizing device for a hollow plastic sheet and a method for producing a hollow plastic sheet using the same.

A hollow plastic sheet formed between a pair of parallel liner (flat plate) portions and a plurality of ribs perpendicular to or oblique to the liner and used between the liners is used for packaging of articles. I came. This hollow plastic sheet has a form in which two liners are bridged by ribs at regular intervals by taking out a plastic material from a mouth of a die having a harmonica cross section.
As shown in FIG. 9, the conventional manufacturing method of this hollow plastic sheet is a process in which a molten plastic material is extruded from a die D and is sized in a gap between upper and lower sizing plates F, F facing each other with a gap. In general, the sheet is taken out by a machine, and is cut into a product sheet by a cutting machine with a predetermined size.
That is, the melt-extruded high-temperature softened hollow plastic sheet has a function of applying a negative pressure by opening a large number of grooves on the surface and is passing through between the upper and lower fixed sizing plates having a cooling function. When the liner of the plastic sheet is sucked toward the sizing plate, the plastic sheet is cooled and solidified by moving while being sized while sliding on the surface of the sizing plate.

This type of sizing plate is generally divided into a plurality of zones, and the cooling temperature and the degree of pressure reduction can be controlled for each sizing plate in each zone. In each block including the sizing plate, cooling pipes and Since decompression piping is circulated and requires high processing costs, there is a problem that the apparatus itself is expensive.
Further, when the take-up speed of the hollow plastic sheet is increased, the frictional resistance between the sizing plate and the hollow plastic sheet is increased and cannot be taken out smoothly. Therefore, the thickness is 3 mm or less and the unit weight (hereinafter referred to as basis weight). However, the production rate was limited to about 8 m / min even in the production of about 400 g / m ² or less.
Furthermore, in the sizing of the conventional sizing plate with the sizing plate, the additive in the plastic of the sheet raw material bleeds out to the surface, and these are volatilized and sublimated. Since the grooves and the grooves were closed, it was necessary to periodically clean the sizing plate, and the work was difficult.

Patent Document 1 describes a synthetic resin hollow sheet forming system using a belt system in order to improve the production rate of a hollow plastic sheet having a low basis weight.
In this synthetic resin hollow body sheet forming system described in Patent Document 1, a plurality of fluid paths are formed in a plate made of a material having high thermal conductivity such as metal that forms a gap surface between upper and lower cooling tanks through which cooling water is circulated. In addition, an opening extending in the width direction for each fluid path is opened in the gap surface of the plate, and a belt having air permeability and water permeability runs on the gap surface of the upper and lower cooling tanks. The sheet is pulled by driving the belt-type former, and negative pressure and / or cooling water is supplied to the plurality of fluid paths. Further, in order to enable high-speed production, an air cooling means is provided in front of the former to form a skin layer on the sheet surface.
However, since the belt needs air permeability and water permeability, it is necessary to use a fine mesh (mesh) or a grooved metal belt, etc., and a shallow mesh mark of the cooling suction shaping means belt is formed on the liner surface. In addition to the above problem, it is impossible to avoid an increase in the cost and complexity of the apparatus, such as a complicated fluid path and increased processing cost of the apparatus, and a belt drive facility.

Further, at least two molding plates arranged parallel to each other with a gap through which the melt-extruded hollow plate (projection) can pass, means for cooling the molding plate, and each molding plate are provided, In a hollow plate (projection) molding apparatus having negative pressure means for making negative pressure, air introduction means for introducing air into the gap and forming an air cushion between the surface of the hollow plate and the surface of the molding plate An apparatus for forming a provided hollow plate (projection) has been proposed (Patent Document 2).
Although the device according to Patent Document 2 is a relatively simple device, an air cushion is formed between the surface of the hollow plate and the surface of the molding plate, so that the cooling effect on the surface of the hollow plate is insufficient. The problem is concerned.

On the other hand, the present applicant has previously proposed an invention obtained through intensive research in order to solve the above-described conventional problems (Patent Document 3).
The invention described in Patent Document 3 is a sizing device that can form a hollow plastic sheet having a relatively large thickness and a high weight per unit area at a higher speed than the conventional one, and a method for producing a hollow plastic sheet using the device. is there.

JP 2002-307534 A JP 2002-103338 A JP 2010-76318 A

However, in the invention described in Patent Document 3, when a hollow plastic sheet having a wide product width, for example, a hollow plastic sheet having a product width of 1380 mm is manufactured, the amount of cooling water in the first decompression section is uniformly managed in the width direction. This makes it difficult to generate temperature spots in the width direction on the surface of the melt-extruded hollow plastic sheet at the inlet of the first decompression section. Due to the temperature spots, a polka dot pattern having a diameter of 1 to 3 mm and a height of 20 to 50 μm is randomly generated, which may cause a problem of surface defects that the appearance is deteriorated.
In view of the above circumstances, the manufacturing apparatus and manufacturing method capable of eliminating the occurrence of a polka dot pattern have been intensively studied, and the surface temperature in the width direction of the hollow plastic sheet and the amount of cooling water supplied in the width direction in the first decompression section The inventors have found that the generation of polka dots can be eliminated by uniformly controlling the amount of discharged water and / or providing an indirect cooling sizing former on the inlet side of the first decompression section.

That is, the present invention provides a more efficient cooling when manufacturing a hollow plastic sheet having a thickness of 1.5 to 8 mm, a product width of 300 to 2500 mm, and a unit weight of about 250 to 2000 g / m ^2. It aims at providing the manufacturing method of the hollow plastic sheet using the sizing apparatus for hollow plastic sheets which can be performed uniformly in the width direction of the said apparatus, and the said apparatus.

The present inventors have found that the above object can be achieved by making the cooling effect of the sizing plate in the product width direction more uniform.
That is, the gist of the present invention is as follows.
(1) A first sizing plate which is in contact with a melt-extruded hollow plastic sheet and a first decompression section composed of a water supply / drainage block, and a second sizing plate which is connected to the first sizing plate and provided on the take-up side A sizing device for a hollow plastic sheet, comprising a second decompression section composed of a decompression box surrounding
In the first sizing plate, water supply slits and drainage slits are alternately arranged in the width direction of the plate, and the water supply / drainage block is opposed to the water supply groove and the drainage slit opposed to the water supply slit and connected to the water supply means. A drainage groove connected to the drainage means is disposed, and the water supply groove is divided into a plurality of water supply means for uniformly supplying water in the width direction of the plate according to the width dimension of the hollow plastic sheet. The drainage groove is provided with drainage means for draining uniformly in the width direction of the plate, the second sizing plate is provided with a suction slit in the width direction of the plate, and the decompression box has a cooling water spray device. And an opening for decompression and drainage, and further, the first sizing plate and the second sizing plate are formed from a pair of upper and lower plates, DOO hollow plastic sheet sizing device according to claim.
(2) Indirect cooling sizing former in contact with a melt-extruded hollow plastic sheet, a first decompression section composed of a third sizing plate and a water supply / drainage block, and connected to the third sizing plate; A sizing device for a hollow plastic sheet comprising a second decompression section composed of a decompression box surrounding a provided second sizing plate, wherein the indirect cooling sizing former is on the contact surface side with the hollow plastic sheet. The third sizing plate is provided with a cooling surface and suction means, and water supply slits and drainage slits are alternately arranged in the width direction of the plate. The water supply / drainage block is connected to the water supply means so as to face the water supply slit. A water supply groove and a drainage groove facing the drainage slit and connected to the drainage means are arranged. The second sizing plate is provided with a suction slit in the width direction of the plate, the decompression box has a cooling water spray device, an opening for decompression and drainage, and indirect cooling sizing A sizing device for a hollow plastic sheet, wherein a former, a third sizing plate, and a second sizing plate are each formed in a pair of upper and lower sides.
(3) An indirect cooling sizing former that is in contact with the melt-extruded hollow plastic sheet, a first decompression section composed of a first sizing plate and a water supply / drainage block, and the first sizing plate connected to the take-up side. A sizing device for a hollow plastic sheet comprising a second decompression section composed of a decompression box surrounding a provided second sizing plate, wherein the indirect cooling sizing former is on the contact surface side with the hollow plastic sheet. A cooling surface and a suction means are provided, the water supply / drainage block is provided with a water supply groove facing the water supply slit and connected to the water supply means, and a drainage groove facing the drainage slit and connected to the drainage means, and The water supply groove is uniformly divided into multiple parts in the width direction of the plate according to the width dimension of the hollow plastic sheet Water supply means that can supply water, the drainage groove is provided with drainage means that can drain uniformly in the width direction of the plate, the second sizing plate is provided with a suction slit in the width direction of the plate, and the decompression box is cooled It has a water spray device, an opening for decompression and drainage, and an indirect cooling sizing former, a first sizing plate, and a second sizing plate are each formed in a pair of upper and lower sides. Sizing device for hollow plastic sheet.
(4) In the first sizing plate, the width of one section of the water supply groove divided into a plurality in the width direction of the plate according to the width dimension of the hollow plastic sheet is 100 to 300 mm. ) Sizing device for hollow plastic sheet.
(5) The indirect cooling sizing former includes a metal block capable of circulating water therein, and a slit formed in the metal block so as to open on a side facing the hollow plastic sheet, and communicates with the slit. The hollow according to any one of claims 2 to 4, further comprising: a duct portion to be connected to the duct portion, and a plurality of connecting plugs that lead to decompression lines arranged in the duct portion in the width direction of the plate in accordance with the width dimension of the hollow plastic sheet. Sizing equipment for plastic sheets.
(6) The contact surface with the hollow plastic sheet in the first, second and third sizing plates and the indirect cooling sizing former is formed of a metal plate having a wettability with a contact angle of 65 ° or less ( A sizing device for a hollow plastic sheet according to any one of 1) to (5).
(7) The metal plate having a wettability with a contact angle of 65 ° or less is formed of brass, copper alloy, or aluminum whose surface is plated or anodized, or has a satin finish, Sizing device for hollow plastic sheet.
(8) The sizing device for a hollow plastic sheet according to any one of (1) to (7), wherein the decompression box is divided into a plurality of parts.
(9) The hollow plastic sheet according to any one of (1) to (8), wherein the hollow plastic sheet to be molded has a thickness of 1.5 to 8 mm and a unit weight of 250 to 2000 g / m ^2. Sizing equipment.

(10) A method for producing a hollow plastic sheet using the hollow plastic sheet sizing device according to (1), wherein a hollow plastic sheet comprising parallel liner portions and a plurality of ribs between the liners is melt-extruded. After that, it is led to a pair of upper and lower first sizing plates, and is provided in the first sizing plate, and is substantially (equal) in the width direction of the sheet on the upper and lower surfaces of the hollow plastic sheet from the water supply slit that leads to the water supply groove connected to the water supply means. The cooling water is supplied to the first sizing plate, and a part of the cooling water is drained by a negative pressure from a draining slit (suction and serving) connected to the drainage means connected to the drainage means, and the sizing plate And a second sage connected to the first sizing plate with a water film formed between the plastic sheet and the hollow plastic sheet. The hollow plastic sheet is guided to the second sizing plate by sliding the hollow plastic sheet to the upper and lower sizing plates by the negative pressure from the suction slit provided on the second sizing plate, and spraying cooling water on the second sizing plate. A method for producing a hollow plastic sheet, characterized by cooling and solidifying.
(11) A method for producing a hollow plastic sheet using the hollow plastic sheet sizing device according to (2), wherein a hollow plastic sheet comprising parallel liner portions and a plurality of ribs between the liners is melt-extruded. After that, it is guided to a pair of upper and lower indirect cooling sizing formers, while the upper and lower liner parts are sucked by the suction means and brought into contact with the cooling surface of the indirect sizing former to cool the surface of the liner part, and then led to the third sizing plate. The cooling water is supplied to the upper and lower surfaces of the hollow plastic sheet from the water supply slit provided in the third sizing plate, and part of the cooling water is drained by negative pressure through the drain slit, and the sizing plate and the hollow plastic sheet With a water film in between, it is connected to the third sizing plate. The hollow plastic sheet is slid to the upper and lower sizing plates by the negative pressure from the suction slit provided on the second sizing plate and sprayed with cooling water on the second sizing plate. A method for producing a hollow plastic sheet, comprising cooling and solidifying the hollow plastic sheet.
(12) A method for producing a hollow plastic sheet using the sizing device for a hollow plastic sheet according to any one of (3) to (9), wherein a parallel liner portion and a plurality of ribs between the liners After the hollow plastic sheet is melt-extruded, it is led to an indirect cooling sizing former having a suction means and a cooling surface on the contact surface side of the hollow plastic sheet, the surface of the hollow plastic sheet is precooled, and the first sizing plate side Direct cooling water that flows backward or leaks from the indirect cooling sizing former side to the first sizing plate while being discharged by the suction means of the indirect cooling sizing former,
The cooling water is supplied to the upper and lower surfaces of the hollow plastic sheet uniformly (substantially) in the width direction of the sheet from the water supply slit connected to the water supply means connected to the water supply means of the water supply / drainage block, and is provided on the first sizing plate. A portion of the cooling water is drained by a negative pressure from a drain slit connected to a drain groove connected to the first sizing plate in a state where a water film is formed between the sizing plate and the hollow plastic sheet. The hollow plastic sheet is slid to the upper and lower sizing plates by the negative pressure from the suction slit provided on the second sizing plate, and the cooling water is sprayed on the second sizing plate to create a hollow Production of hollow plastic sheets characterized by cooling and solidifying plastic sheets Method.
(13) A hollow plastic sheet obtained by the method for producing a hollow plastic sheet according to any one of (10) to (12).

  The present invention uniformly controls the surface temperature in the width direction of the hollow plastic sheet and the amount of cooling water supplied and discharged in the width direction in the first decompression section, and / or indirectly on the inlet side of the first decompression section. By providing a cooling sizing former, a sizing device that can eliminate the occurrence of a polka dot pattern, can form a hollow plastic sheet having a relatively large thickness, a high weight per unit and a wide product width at a higher speed than before, and the device The manufacturing method of the hollow plastic sheet using this can be provided.

(A) Schematic sectional view of the sizing device according to the first aspect of the present invention, (b) A transverse sectional view of the hollow plastic sheet at the section A-A ′ of (a). It is principal part explanatory drawing of the sizing apparatus of the 1st aspect of this invention. It is a top view of a lower sizing plate. It is explanatory drawing of the water supply / drain block of a lower side 1st sizing plate. It is a schematic cross section of the sizing device according to the second and third aspects of the present invention. It is principal part explanatory drawing of the sizing apparatus of the 2nd aspect of this invention. It is (a) perspective view, (b) front sectional view, (c) enlarged side sectional view of an indirect cooling sizing former. It is principal part explanatory drawing of the sizing apparatus of the 3rd aspect of this invention. It is explanatory drawing of the conventional manufacturing method.

In the present invention, when a hollow plastic sheet having a thickness of 1.5 to 8 mm, a product width of 300 to 2500 mm, and a unit weight of about 250 to 2000 g / m ² is manufactured, more efficient cooling is performed in the width direction of the hollow plastic sheet. An object of the present invention is to provide a sizing device for a hollow plastic sheet that can be uniformly performed and a method for producing a hollow plastic sheet using the device. Therefore, in the present invention, as a device used in the vicinity of the contact point with the hollow extruded plastic sheet, the sizing device of the first mode, the second mode, or the third mode is used, and the second sizing plate connected thereto is used. It is what is used.

A sizing device for a hollow plastic sheet according to a first aspect of the present invention is connected to the first sizing plate, which includes a first sizing plate that is in contact with a melt-extruded hollow plastic sheet and a water supply / drainage block, and the first sizing plate. A sizing device for a hollow plastic sheet comprising a second decompression section composed of a decompression box surrounding a second sizing plate provided on the take-up side, wherein the first sizing plate has a water supply slit in the width direction of the plate And drainage slits are arranged alternately. The water supply / drainage block is provided with a water supply groove connected to the water supply means so as to face the water supply slit and a drainage groove connected to the drainage means so as to face the drainage slit. In addition, the water supply groove is provided with water supply means that is divided into a plurality of parts in order to supply water uniformly in the width direction of the plate according to the product width dimension of the hollow plastic sheet. Further, the drainage groove is provided with drainage means for draining uniformly in the width direction of the plate. Further, the second sizing plate is provided with a suction slit in the width direction of the plate, and the decompression box has a cooling water spray device and openings for decompression and drainage. Furthermore, the first sizing plate and the second sizing plate are formed of a pair of upper and lower plates, and the gap between the pair of plates is dimensioned to correspond to the thickness of the hollow plastic.
In the present invention, “drainage” in the drainage slit, drainage groove, and drainage means shall include the actions and effects of “suction” and “water absorption”, respectively. It may be expressed as “drainage”, “drainage (suction)”, or the like.

Hereinafter, the sizing device for a hollow plastic sheet according to the first aspect of the present invention will be described with reference to the drawings.
FIG. 1A is a side view showing an outline of a hollow plastic sheet sizing device 1A according to the first embodiment of the present invention in the flow direction of a hollow plastic sheet (hereinafter referred to as “M direction”). It is composed of a section 10 and a second decompression section 11.
In each decompression section, the first sizing plate 2 and the second sizing plate 3 connected to each other are provided up and down with a gap corresponding to the thickness of the hollow plastic sheet. Sizing.
First, a hollow plastic material is discharged from a predetermined die D, and as shown in FIG. 1B, a sheet comprising a pair of parallel liners L and a plurality of vertical ribs R provided between the liners L. A hollow plastic sheet (hereinafter, simply referred to as a “molded body”) S formed into a shape, which is precooled by cold air, and then provided in the inlet section of the hollow plastic sheet sizing device 1 10 is sent.

  In the first decompression section 10, as shown in an enlarged view in FIG. 2, the water supply slits 5 and the suction / drain slits 4 are alternately arranged in the first sizing plate 2 in the width direction of the plate. The water supply / drainage block 20 is provided with a water supply groove 5G connected to the water supply means so as to face the water supply slit 5 and a suction / drainage groove 4G connected to the suction / drainage means so as to face the suction / drainage slit 4. ing. The first sizing plate 2 and the water supply / drainage block 20 are configured, and are fixed to a decompression box 6 described later by a connecting bolt 21 provided in the water supply / drainage block 20. The molded body is introduced into the open first sizing plate 2 (in the present invention, the gap between the upper and lower sizing plates facing each other with a gap is simply referred to as a sizing plate. Sometimes).

Further, the water supply groove 5G is provided with water supply means that is divided into a plurality of parts in order to supply water uniformly in the width direction of the plate according to the product width dimension of the hollow plastic sheet. Further, the suction / drainage groove is provided with suction / drainage means for suctioning and draining uniformly in the width direction of the plate. That is, as shown in FIG. 3, the first sizing plate 2 and the second sizing plate 3 have a width WL that can correspond to the product width dimension of the hollow plastic sheet.
Furthermore, the water supply groove 5G of the water supply / drainage block 20 arranged to face the water supply slit 5 of the first sizing plate 2 constituting the first pressure reduction section 10 supplies water uniformly in the width direction of the plate in FIG. Therefore, it is divided into seven parts B1 to B7. A distribution pipe is connected to the water receiving hole 80 for each of the divided water supply grooves, and the cooling water is supplied to each of the fractionated portions by a means such as a water supply pump with a flow meter (not shown). Is done. Similarly to the water supply groove 5G, the suction / drain groove 4G is provided with a suction hole (mouth) at least for each fractionation section, and a suction hose is connected to the plate in the width direction by means such as a vacuum pump (not shown). Uniform suction and drainage.

In the present invention, a plurality of water supply slits 5 and drainage (suction) slits 4 are provided. For example, when two slits are provided as shown in FIG. 1A, drainage (suction) -water supply-drainage (suction) is provided. ) -Slits are alternately provided to repeat water supply, drainage (suction) and water supply.
The reason why drainage (suction) -water supply-drainage (suction) -water supply and drainage (suction) are performed first is to prevent water from flowing back to the die D side. That is, in the vicinity of the entrance of the first sizing plate 2, the water from the water supply slit 5 is sucked by the drainage slit 4 while forming a water film between the molded body and the sizing plate, and is shifted to the downstream side (M direction). While supplying the cooling water from the first water supply slit 5, a part of the cooling water is drained from the adjacent drain (suction) slit 4, and then the cooling water is supplied again to the adjacent drain (suction). By draining a part of the cooling water from the slit 4 again, the cooling efficiency can be increased.
This cooling water is supplied not only for cooling the molded body but also for forming a water film in the gap between the first sizing plate 2 and the second sizing plate 3 and the molded body S, and preferably supplied. Control is performed so that about 25 to 50 mass% of the cooling water is drained from the drain (suction) slit 4.
The degree of decompression of the first decompression section 10 composed of the first sizing plate 2 and the water supply / drainage block 20 is adjusted by a vacuum pump directly connected to the drainage (suction) slit 4, but normally the vacuum pump is used in a fully opened state. Therefore, the amount of cooling water drainage is substantially controlled by setting the amount of cooling water supplied to the water supply slit 5 and the width dimension of the drainage (suction) slit 4.

The width of the water supply slit 5 is preferably about 0.5 to 1.5 mm in order to uniformly supply the cooling water to the entire groove. The water supply slit 5 is a water supply means such as a water supply pump with a water meter. It is connected with. On the other hand, the width of the drainage (suction) slit 4 is preferably about 1 to 2 times the width of the water supply slit, for example, about 0.5 to 3 mm, in order to reliably suck and drain the water. As described above, the drainage (suction) slit 4 is connected to drainage means such as a vacuum pump to control the degree of decompression of the decompression section 10.
The thickness of the first sizing plate 2 is about 10 to 20 mm, and the water supply / drainage block has a height of about 50 to 80 mm because a plurality of water supply slits 5 and drainage (suction) slits 4 are provided in the longitudinal direction.
In implementation, the supply water amount and the widths of the water supply slit 5 and the drainage (suction) slit 4 are adjusted so that the purpose of the cooling water can be realized.

With the above configuration, the cooling of the liner is made faster, so that the rib is also cooled more quickly.
As shown in FIG. 1A, the molded body S is first supplied from the first water supply slit 5 in the vicinity of the inlet of the first sizing plate 2 in the process of passing through the first sizing plate 2 of the first decompression section 10. Water cooling is started in contact with the generated cooling water, and a part of the water supply is drained from the drainage (suction) slit 4, but a water film is formed between the molded body and the first sizing plate 2 by the remaining cooling water. Is formed and transferred to the second sizing plate 3 provided in the second decompression section 11 together with the molded body. Due to the presence of this water film, the take-up resistance of the molded body can be significantly reduced as compared with the case of using a conventional sizing device, and thus the molding speed can be increased.
As described above, the hollow plastic sheet S and the water film, which have traveled through the gap between the upper and lower first sizing plates 2 and partially molded, cooled and solidified, are subsequently provided in a pair of upper and lower sides with a gap therebetween. It is taken into the gap between the plates 3 at a predetermined speed. This take-up is performed by a take-up machine 24 and a vacuum suction described later.

The second decompression section 11 includes a decompression box 6 that surrounds the second sizing plate 3 provided with a plurality of suction slits 13. The thickness of the second sizing plate 3 is about 10 to 20 mm. The size, structure, and the like of the decompression box 6 are determined according to the raw material resin, the melt extrusion temperature of the molded body S, the traveling speed, and the like, and may be divided into a plurality of parts depending on cooling conditions.
FIG. 1A shows an example in which the decompression box 6 is divided into two parts. In the front decompression box 7 and the rear decompression box 8, the molded body S taken from the first decompression section 10 is cooled and In order to promote solidification and molding, cooling water is sprayed from a plurality of spray nozzles 14 which are cooling water spray devices toward the second sizing plate 3 provided with a plurality of suction lits 13, and the second sizing plate 3. The molded body S is cooled via the. As a cooling method for the second sizing plate 3, cooling may be performed by passing cooling water through the second sizing plate 3 instead of the cooling water spray, or the cooling water spray and the second sizing plate 3 may be cooled. Cooling by passing cooling water may be used in combination.
The decompression boxes 7 and 8 can be adjusted in degree of decompression by pressure regulating means 16 with a solenoid valve and decompression means 15 including a vacuum pump connected via a decompression tank (not shown). Yes. When the decompression box 6 is decompressed, negative pressure is applied from the plurality of suction slits 13 provided in the second sizing plate 3, whereby air in the gap between the second sizing plates 3 is sucked and from the take-up machine 24. Since it is taken up, the liner L of the molded body S is pulled toward the upper and lower second sizing plates 3 to ensure the thickness of the molded body S and to obtain the smoothness of the surface of the liner.

  In FIG. 1A, the pre-stage decompression box 7 and the post-stage decompression box 8 are decompressed by a common decompression means 15. Each chamber is provided with a pressure adjusting means 16 with a solenoid valve, and is controlled so that the internal pressures of the decompression boxes 7 and 8 become predetermined values. When the pressure in each of the decompression boxes 7 and 8 is lower than a predetermined value, the pressure is adjusted by introducing outside air with an electromagnetic valve attached to the pressure adjusting means 16. The pressure reducing boxes 7 and 8 may be the same pressure or different pressures, but usually, the latter pressure reducing box 8 has a slightly lower negative pressure than the preceding pressure reducing box 7 so as not to suck the water film as much as possible. Take over effectively.

The second sizing plate 3 surrounded by the decompression box 6 is provided with a plurality of suction slits 13 in the plate width direction as described above. At this time, the second sizing plate 3 surrounded by the preceding decompression box 7 is relatively dense, while the second sizing plate 3 enclosed by the succeeding decompression box 8 is relatively sparse, respectively. 13 is preferably provided.
The width of the suction slit 13 is preferably about 0.5 to 1.5 mm so that the water film is not sucked as much as possible and the air in the gap is sucked.
By comprising in this way, the water film reduced by the suction | attraction | suction for improving smoothness by the front | former pressure reduction box 7 side can be maintained to the exit vicinity of the back | latter stage pressure_reduction | reduced_pressure box 8, and a taking-out effect is exhibited efficiently. In addition, it is possible to finish the molding by cooling and solidification, which is preferable.
The water temperature of the cooling water supplied to the water supply slit 5 varies depending on the cooling and solidification characteristics of the raw material resin of the plastic sheet to be molded, and is not necessarily a room temperature or lower water temperature. For example, in the case of polycarbonate, the water temperature may be a hot water temperature. is there.
This is because the polycarbonate is an amorphous thermoplastic resin, so the cooling rate and the solidification rate are proportional to each other, and the shape of the molded body is rapidly fixed due to a rapid temperature change. It is preferable to mold by slowly cooling with hot water temperature.
The water in the front and rear decompression boxes 7 and 8 is discharged from the opening 22 by a drain means (not shown) such as a drain pump.

FIG. 3 is a plan view showing a mounting state of the lower first sizing plate 2 and the second sizing plate 3 connected thereto in the first decompression section 10 and the second decompression section 11 of the sizing apparatus of the present invention. FIG.
The first sizing plate 2 attached to the water supply / drainage block 20 fixed to the decompression box 6 by the connecting bolt 21 opens to the side of the molded body (upper side in FIG. 2) that travels across the entire width direction of the plate. The plate and the water supply / drainage block 20 are provided with water supply slits 5 and drainage (suction) slits 4 having predetermined widths and depths that are consistent with each other. The width dimensions and the number of slits of the drainage (suction) slit 4 and the water supply slit 5 are determined according to the melt extrusion temperature of the molded body S and the traveling speed, and FIG. 3 shows a total of four cases. .
The second sizing plate 3 on the take-up side is provided with a plurality of slit-like suction slits 13 at appropriate intervals. The suction slit 13 is a through-hole extending over the entire thickness of the plate, and by applying a negative pressure to the gap, a molded body that is running from the upper and lower surfaces of the first and second sizing plates 2 and 3. A tensile force is applied to the upper and lower liners of S.
The number of suction slits 13, installation locations, and the like are appropriately determined according to the type of resin, basis weight, and molding speed of the hollow plastic sheet to be molded.
The above metal sizing plate is fixed to the base plate 23 by fixing means such as bolts both in the upper and lower sides. In addition, a reinforcing material (beam) is disposed in the longitudinal (M) direction in order to prevent the sizing plate from being bent horizontally due to its own weight in the width direction.
Below the second sizing plate 3 on the lower side, a plurality of spray nozzles 14 are provided as cooling water spray devices for cooling the second sizing plate 3, and the amount of water supplied is a metering pump (not shown). It is controlled by. In addition, the spray nozzle 14 appropriately adjusts the installation interval and spray angle of the spray nozzle so that the spray amount can be made uniform in the width direction in the depth direction in FIG. 1A, that is, the width direction of the sizing plate. A plurality of spray nozzles are arranged.

  The first and second sizing plates 2 and 3 on the lower side have been described above, but the upper sizing plate is also provided with a water supply slit, a drainage slit, and a suction slit at vertically symmetrical positions.

A sizing device for a hollow plastic sheet according to a second aspect of the present invention includes an indirect cooling sizing former that comes into contact with a melt-extruded hollow plastic sheet, a first decompression section that includes a third sizing plate and a water supply / drainage block, A sizing device for a hollow plastic sheet comprising a second decompression section connected to a third sizing plate and comprising a decompression box surrounding a second sizing plate provided on the take-up side.
The indirect cooling sizing former has a cooling surface and suction means on the contact surface side with the hollow plastic sheet, and the third sizing plate has water supply slits and drainage (suction) slits arranged alternately in the width direction of the plate. The water supply / drainage block includes a water supply groove connected to the water supply means facing the water supply slit, and a drainage (suction) groove connected to the water discharge (suction) means facing the water discharge (suction) slit. The second sizing plate is provided with a suction slit in the width direction of the plate, the decompression box has a cooling water spray device, an opening for decompression and drainage, and A hollow characterized in that an indirect cooling sizing former, a third sizing plate, and a second sizing plate are respectively formed in a pair of upper and lower sides. Is a Las tic sheet for sizing equipment.

Hereinafter, the sizing device for a hollow plastic sheet according to the second aspect of the present invention will be described with reference to the drawings. FIG. 5 is a side view showing an outline of the sizing apparatus 1B for the hollow plastic sheet according to the second aspect of the present invention in the M direction of the hollow plastic sheet, and shows the indirect cooling sizing former 30, the first pressure reducing section 100, and the second pressure reducing section. And section 11.
In each decompression section, the second sizing plate 3 connected to the third sizing plate 70 is provided up and down facing each other with a gap corresponding to the thickness of the hollow plastic sheet. Sizing. The apparatus of the second aspect is different from the apparatus of the first aspect in the combination of the indirect cooling sizing former 30 and the first decompression section 100.
As shown in FIG. 5, first, a hollow plastic sheet is discharged from a predetermined die D, and the hollow plastic sheet is pre-cooled with cold air, and then the indirect cooling sizing force provided at the inlet portion of the sizing device 1B for the hollow plastic sheet. Sent to the mer 30.

In the indirect cooling sizing former 30 in the second aspect of the invention, particularly if the cooling surface is provided with a cooling surface on the contact surface side with the hollow plastic sheet and a suction means for sucking the hollow plastic sheet on the cooling surface side. The structure is not limited, but as an example, a duct having a metal block capable of circulating water inside and a slit formed in the metal block so as to open on the opposite side of the hollow plastic sheet, and communicating with the slit Further, it is possible to use a duct provided with a suction connection hole that leads to a plurality of decompression lines arranged in the width direction of the plate according to the width dimension of the hollow plastic sheet.
That is, as shown in the side view of FIG. 6, the cooling surface 33 on the contact surface side with the hollow plastic sheet, the suction slit 34 opened on the cooling surface 33 side, the suction duct 35 communicating with the suction means, and the suction means (not shown) ) Are arranged at appropriate intervals in the width direction. FIG. 7 shows (a) a perspective view, (b) a front sectional view, and (c) a partial enlarged side sectional view of an example of a lower indirect cooling former.
In FIG. 8, two indirect cooling formers 31 and 32 are connected. However, in the sizing device for a hollow plastic sheet of the present invention, the number of indirect cooling formers is not limited, and the length in the M direction is also limited. It is determined from the thickness of the hollow plastic sheet, the basis weight, the circulation amount of the cooling medium such as water, and the like.

The sizing device for a hollow plastic sheet according to the second aspect of the present invention is different from the sizing plate in that the third sizing plate supplies water uniformly in the width direction of the plate in the first sizing plate of the first aspect. While the groove 5G is completely fractionated using the fractionation block, the water supply groove 50G is not completely fractionated using the fractionation block in the width direction, but only the connection portion of the water supply hose. Are arranged substantially evenly in the width direction.
That is, in FIG. 5, the first decompression section 100 is different from the first decompression section 10 of the first embodiment. However, also in the second aspect, the configuration of the apparatus after the second sizing plate is the same as that in the first aspect, and the description thereof is omitted. In addition, as a cooling method of the 2nd sizing plate 3, you may cool by letting a cooling water pass in the 2nd sizing plate 3 instead of a cooling water spray similarly to a 1st aspect, or a cooling water spray and Cooling by passing cooling water through the second sizing plate 3 may be used in combination.

A sizing device for a hollow plastic sheet according to a third aspect of the present invention includes an indirect cooling sizing former that is in contact with a melt-extruded hollow plastic sheet, a first decompression section that includes a first sizing plate and a water supply / drainage block, A sizing device for a hollow plastic sheet, comprising a second decompression section connected to a first sizing plate and comprising a decompression box surrounding a second sizing plate provided on the take-up side.
The indirect cooling sizing former is provided with a cooling surface and suction means on the contact surface side with the hollow plastic sheet, and has the same configuration as that described in the second aspect, and includes a first sizing plate and a water supply / drainage block. One decompression section has the same configuration as that of the first embodiment.
That is, as shown in FIG. 8, the water supply / drainage block 20 of the first sizing plate 2 has a water supply groove 5 </ b> G facing the water supply slit 5 and connected to the water supply means and a water discharge (suction) slit 4. The drainage (suction) groove 4G connected to the means is arranged, and the water supply groove 5G is divided into a plurality of parts in the width direction of the plate according to the width dimension of the hollow plastic sheet, as already described with reference to FIG. The drainage (suction) groove is provided with drainage (suction) means that can uniformly drain (suction) in the width direction of the plate. In the third aspect, the configuration of the apparatus after the second sizing plate is the same as that in the first aspect, and the description thereof is omitted. Moreover, as a cooling method of the 2nd sizing plate 3, you may cool by letting a cooling water pass in the 2nd sizing plate 3 instead of a cooling water spray like a 1st aspect, or a cooling water spray and Cooling by passing cooling water through the second sizing plate 3 may be used in combination.

  In the water supply / drainage block of the device invention of the first and third aspects of the present invention, the width of one section of the water supply groove divided into a plurality in the width direction of the plate according to the width dimension of the hollow plastic sheet is the width direction of the plate It is preferable that it is 100-300 mm from a viewpoint of equalization of the water supply amount. If it is 100 mm or more, the complexity due to an increase in the number of water supply pipes (hose) due to an increase in the number of fractions and an increase in the processing cost of the water supply / drainage block can be suppressed. The water supply amount in the width direction of the plate can be made uniform.

The first and third sizing plates 2 and 70 and the second sizing plate 3 to which these are connected are for the purpose of forming, cooling and solidifying the hollow plastic sheet S. It is desirable to use a high-rate metal. In particular, the sizing apparatus of the present invention has a thickness of about 1.5～8Mm, unit weight (basis weight) of at 250~2000g / m ^2, be used in the production of hollow plastic sheets extensive width dimension 300~2500mm it can.

  The sizing device for a hollow plastic sheet of the present application has been described above. In the above description, the rib R provided between the liners L is described as being in a direction perpendicular to the liner L. You may have the rib R of the diagonal direction with respect to L. FIG. Moreover, although the decompression means and the drainage means of the decompression boxes 7 and 8 are provided separately, the decompression means may be connected to the opening 22 and the drainage and decompression may be performed simultaneously. Furthermore, although the description has been made using a common vacuum pump as the decompression means for the decompression boxes 7 and 8 divided into two, the decompression box 7 and the rear decompression box 8 may be provided independently of each other.

Next, the manufacturing method of the hollow plastic sheet of this invention is demonstrated.
A first aspect of the method for producing a hollow plastic sheet according to the present invention is a method for producing a hollow plastic sheet using the hollow plastic sheet sizing device according to the first aspect, wherein a parallel liner portion is disposed between the liner portion and the liner. After melting and extruding a hollow plastic sheet composed of a plurality of ribs, the hollow plastic sheet is guided to a pair of upper and lower first sizing plates, and is provided on the first sizing plate, and the upper and lower sides of the hollow plastic sheet are connected to the water supply groove connected to the water supply means. The cooling water is supplied to both sides in a sheet width direction (substantially) uniformly, and is provided from the drainage (suction) slit provided on the first sizing plate and connected to the suction / drainage groove connected to the suction / drainage means. A part of the water was drained by negative pressure, and a water film was formed between the sizing plate and the hollow plastic sheet. In this state, the hollow plastic sheet is slid to the upper and lower sizing plates by the negative pressure from the suction slit provided in the second sizing plate and guided to the second sizing plate connected to the first sizing plate. Cooling water is sprayed on the sizing plate to cool and solidify the hollow plastic sheet.

In the method of the present invention, immediately after being melt-extruded as a hollow plastic sheet S and immediately before being led to the first sizing plate 2, the temperature of the surface of the melt-extruded molded body is lowered by precooling with a gas such as air. Is preferable from the viewpoint of molding stability.
As described above, in the first sizing plate 2, the supply and drainage of the cooling water are repeated, and about 50 to 75 mass% of the supplied cooling water is transferred to the second sizing plate 3 side as a water film. It is preferable.
The negative pressure of the decompression box 6 is controlled to about 3 to 9 kPa. When the decompression box is divided into two as in the above example, it is preferable that the negative pressure in the rear-stage decompression box 8 is slightly lower than that in the front-stage decompression box 7.

The thermoplastic resin to which the method for producing a hollow plastic sheet of the present invention can be applied is a high density, of course, these crystalline thermoplastic resins conventionally used as hollow plastic plates such as polyolefin resins such as polypropylene and polycarbonate resins. Hollow plastic sheets of various thermoplastic resins such as polyethylene and linear low-density polyethylene can be produced, and in particular, it can be suitably used for the production of polypropylene resin hollow plastic sheets.
For the purpose of improving the color pigment and moldability, the raw material resin for the hollow plastic sheet may be blended with a filler as an auxiliary material.
The auxiliary material is not particularly limited, but talc, calcium carbonate, and the like are preferable in consideration of the balance with cost, formability, handleability, and the like.
Further, in addition to the filler, an antioxidant, an ultraviolet absorber, an antistatic agent, an antibacterial agent, a flame retardant, a light stabilizer, a lubricant such as calcium stearate, etc., in any amount, any kind, and combination as necessary. May be.

  Further, the hollow plastic sheet that can be produced by the production method of the present invention is not limited to a simple extruded raw material, and an antistatic layer is provided on one or both surfaces of the upper and lower liners. The sheet body may be coextruded into multiple layers.

Next, a second aspect of the method for producing a hollow plastic sheet of the present invention is a method for producing a hollow plastic sheet using the hollow plastic sheet sizing device of the second aspect, wherein the parallel liner portion and After melt extrusion of a hollow plastic sheet composed of a plurality of ribs between the liners, it is led to a pair of upper and lower indirect cooling sizing formers, and the upper and lower liner parts are sucked by suction means and brought into contact with the cooling surface of the indirect sizing former. The surface of the section is cooled, then led to the third sizing plate, and the cooling water is supplied to the upper and lower surfaces of the hollow plastic sheet from the water supply slit provided in the third sizing plate, while the cooling water is supplied by the drainage (suction) slit A part of the sizing plate and hollow plastic are drained by negative pressure. In a state where a water film is formed between the two sizing plates, the hollow plastic sheet is guided to the second sizing plate connected to the third sizing plate, and the hollow plastic sheet is moved up and down by the negative pressure from the suction slit provided in the second sizing plate. The hollow plastic sheet is cooled and solidified by sliding to the side and spraying cooling water onto the second sizing plate.
Also in the manufacturing method of the second aspect, the process after being led to the second sizing plate, the temperature condition, the pressure condition, the corresponding raw material resin, etc. are the same as the contents described in the manufacturing method of the first aspect, so that the explanation is given. Omit.

Furthermore, a third aspect of the method for producing a hollow plastic sheet of the present invention is a method for producing a hollow plastic sheet using at least the hollow plastic sheet sizing device of the third aspect, wherein the parallel liner portion and After melt extrusion of a hollow plastic sheet consisting of a plurality of ribs between liners, the hollow plastic sheet is led to an indirect cooling sizing former having a suction means and a cooling surface on the contact surface side of the hollow plastic sheet, and the surface of the hollow plastic sheet is precooled, In addition, the direct cooling water that flows backward or leaks from the first sizing plate side to the indirect cooling sizing former side is discharged by the suction means of the indirect cooling sizing former, guided to the first sizing plate, and connected to the water supply means of the water supply / drain block. Hollow plus from the water supply slit leading to the water supply groove From the drainage (suction) slits that supply cooling water to the top and bottom surfaces of the backsheet evenly (substantially) in the width direction of the sheet, and that lead to the drainage (suction) grooves provided on the first sizing plate and connected to the suction and drainage means A part of the cooling water is drained by a negative pressure, and a water film is formed between the sizing plate and the hollow plastic sheet, and then led to a second sizing plate connected to the first sizing plate. The hollow plastic sheet is slid to the upper and lower sizing plates by negative pressure from the provided suction slit, and cooling water is sprayed on the second sizing plate to cool and solidify the hollow plastic sheet. To do.
Also in the manufacturing method of the third aspect, the process after being led to the second sizing plate, the temperature condition, the pressure condition, the corresponding raw material resin, etc. are the same as the contents described in the manufacturing method of the first aspect, so that the explanation is given. Omit.

  The present invention also provides a hollow plastic sheet obtained by any one of the methods for producing a hollow plastic sheet of the present application.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention, this invention is not limited to these Examples at all.
Example 1
As the first sizing plate, a side sectional view in FIG. 2 and a water supply / drainage block in FIG. 4 were used. First, as the material for the first and second sizing plates, aluminum whose surface was anodized (wetability was a contact angle of 54.0 °) was used.
As a whole configuration, a sizing apparatus whose schematic diagram is shown in FIG. That is, the length L1 of the first sizing plate 2 of the sizing device was 107 mm, and the length of the second sizing plate 3 was 1564 mm. Further, the effective width WL of the sizing device was set to 1550 mm corresponding to the product width 1320 mm of the hollow plastic sheet.

<First sizing plate>
As shown in FIG. 2, the first sizing plate 2 is configured to be symmetrical in a pair of upper and lower sides, and a water supply / drain block 20 is attached to the upper and lower portions thereof. The entire water supply / drainage block 20 has a thickness of 64 mm and a length of 107 mm. The first sizing plate 2 is drained (suction), supplied with water, drained (suction), and supplied in the order of 19 mm, 36 mm, 56 mm, and 82 mm from the entrance side. And provided with a drainage groove 4G and a water supply groove 5G facing the slits.
The width of the water supply slit of the first sizing plate 2 is 0.5 mm in order to uniformly discharge in the width direction of the molded product through the water supply groove 5G, and the width of the drainage (suction) slit is 1 for stable drainage. It was set to 0.0 mm, and drainage was performed while suctioning with a vacuum pump through the drainage groove 4G.
The water supply / drainage block has an effective width corresponding to the product width as shown in the lower side water supply / drainage block in FIG. 4, and in this embodiment, both the drainage groove 4G and the water supply groove 5G have a groove width of 10 mm and a groove depth. Was 15 mm. In order to equalize the amount of water supply in the product width direction, as shown in FIG. 4A, in the width direction of the water supply groove 5G, it was divided into 7 blocks B1 to B7 at intervals of 160 mm to 240 mm.
In each block, a water supply hose is connected at the water supply hose connection port 80, and a predetermined water supply amount measured by a flow meter is supplied.
On the other hand, at the upper part (not shown) of the drainage groove 4G, the connection ports of the decompression suction line are arranged at intervals substantially corresponding to the divided blocks of the water supply groove, and drainage (suction) is performed substantially evenly in the width direction. The structure.
The thickness of the first sizing plate was 14.5 mm.

<Second sizing plate>
The thickness of the second sizing plate 3 to which the first sizing plate is connected is 15 mm, and in the total length of 1564 mm, the suction slits 13 penetrating the entire thickness starting from 25 mm from the end of the connecting portion are arranged in four rows at intervals of 25 mm, 50 mm. Two rows were provided at intervals, two rows at 70 mm intervals, two rows at 90 mm intervals, four rows at 120 mm intervals, and two rows at 200 mm intervals.

<Decompression box>
A decompression box having a height (depth) of 350 mm, a width of 1550 mm, and a length (running direction of the molded body) of 1030 mm and an internal volume of about 580 liters (L) was manufactured, and was divided into a front stage and a rear stage. The decompression operation is configured such that decompression means connected to a decompression tank and a vacuum pump is connected to the discharge side of each decompression box and decompression in the decompression box and cooling water are conducted simultaneously. The vacuum pressure was arbitrarily controlled according to the thickness of the hollow plastic sheet with the electromagnetic valve of the pressure adjusting means. The inlet width and outlet width of the sizing plate were as close as possible to the width of the molded body, but the gap was closed with a Teflon (registered trademark) sheet or the like to enable decompression.
<Cooling water>
Cooling water spray devices with 7 spray nozzles (manufactured by Miri no Ikeuchi Co., Ltd .: product number SSXPO40 1 / 4M) in the width direction are arranged in four rows above and below the second sizing plate, enabling a predetermined amount of water to be supplied from the water pump. did. In addition, the upper and lower water supply grooves of the first sizing plate are configured to be capable of supplying quantitative water independently. The cooling water temperature was 15 ° C. for the water supply groove and 15 ° C. for the cooling water spray device.

A hollow plastic sheet was formed using the above sizing apparatus for hollow plastic.
<Molding of hollow plastic sheet>
As a plastic resin material, a polypropylene block copolymer containing 4% by mass of ethylene (grade name: E601, MI = 0.8 (g / 10 min)) manufactured by Prime Polymer Co., Ltd., having a thickness of 3.0 mm and a basis weight of 500 g / The goal was to mold a hollow plastic sheet (type: A-3-50N) with m ² and a target leg spacing of 3.8 mm. A resin flow path provided with a metal core (core) capable of blowing air to form a hollow chamber is shaped like a harmonica, extruded from a die with a width of 1450 mm at 230 ° C., and molded by neck-in. In the state of about 1320 mm in width, the hollow plastic sheet was produced through the first sizing plate and the second sizing plate.
As shown in Table 1, the manufacturing conditions before sizing were set such that the forming speed was 10 m / min, the distance from the die outlet to the inlet of the first sizing plate was 140 mm, and air at a temperature of 25 ° C. was applied at an air volume of 1400 L / min. Precooled. Subsequently, it led to the sizing apparatus shown in FIG.
The total amount of water supplied to the first sizing plate was 15 L / min at the top and bottom, and this was supplied from each of the two rows of water supply slits 5 at 7.5 L / min. On the other hand, the drainage slit 4 was sucked to be discharged at 3.0 L / min in each of the upper and lower rows. Thereby, the carry-in rate to the second sizing plate side of the cooling water was controlled to 60%.
Next, in the decompression box 6 in which seven showers per row are attached to each of the upper and lower rows so that spraying can be performed uniformly in the width direction, while spraying 15 ° C. water at 50 L / min in the upper and lower directions, The hollow plastic sheet was molded with the front side at a reduced pressure (vacuum) degree of 3.2 kPa and the rear side at a (vacuum) degree of 2.2 kPa.

The surface state and surface smoothness of the obtained hollow plastic sheet were measured and evaluated as follows.
<Evaluation>
(1) Surface state (polka dot pattern): A hollow plastic sheet was cut 100 mm × full width in the flow direction, and the number of polka dots was measured by visual confirmation. The determination method was “◎” for no polka dots, “◯” for less than 10, “Δ” for 10 to less than 100, and “x” for 100 or more.
(2) Surface smoothness (amount of dents): The surface smoothness was measured by measuring the surface roughness of a hollow plastic sheet 100 mm × full width in the flow direction with a 5 μmR diamond stylus according to JIS B 0601. Measure 6 points of arithmetic average surface roughness (Ra; μm) under the conditions of 0.5 mm / second, cut-off 0.8 mm, measurement length 2.4 mm, and vertical magnification 2000 times, and adopt the maximum value of each as the measured value. did.
The manufacturing conditions and evaluation results are summarized in Table 1.

Example 2
Instead of the first sizing plate water supply / drainage block of the first embodiment, the third sizing plate (to be described later) provided with the water supply / drainage block 200 shown in FIG. A hollow plastic was molded.
<Indirect cooling sizing former>
FIG. 6 shows a side sectional view, FIG. 7 shows (a) a perspective view, (b) a front sectional view, and (c) a partially enlarged side sectional view.
In the second embodiment, a suction slit having a width of 43 mm in the longitudinal (M) direction, a thickness (height) of 60 mm, a width of 1550 mm, and a width of 1 mm opened on the cooling surface 33 side in the center in the longitudinal direction is shown in FIG. It is provided with a width of 1400 mm excluding 65 mm from both ends in the direction. The suction slit 34 penetrates a suction duct 35 having a diameter of 10 mm connected to the suction means, and the suction duct 35 is sucked into the suction means at intervals of 165 mm, 200 mm, and 210 mm in the width direction. A pair of upper and lower indirect cooling sizing formers having seven connection holes 37 was prepared. The inlet side of the cooling surface 33 of the indirect cooling sizing former was chamfered to facilitate the introduction of the molded body, and the cooling surface was subjected to 400 blast sandblasting after hard chrome plating.

<Third sizing plate>
The third sizing plate in the side sectional view shown in FIG. 6 is the drainage slit 4 and the water supply slit 5 in the first sizing plate. Is the same as the first sizing plate of Example 1 except that it is not fractionated.
The second sizing plate and the decompression box were the same as those in Example 1.

<Molding of hollow plastic sheet>
Using the same raw materials as in Example 1, the same varieties were extruded from the same die at a rotation speed of a melt extruder of 34 rpm and a molding speed of 5.3 m / min, and the above indirect cooling sizing former and the third sizing plate were extruded. Then, a hollow plastic sheet was manufactured through a second sizing plate.
As shown in Table 1, the production conditions before sizing were the same as those in Example 1, except that precooling was performed by applying air at a temperature of 25 ° C. at an air volume of 1350 L / min. In the indirect cooling sizing former, 15 ° C. cooling water is circulated through the water pipe 36 at a rate of 8 to 9.5 L / min to cool, and the suction slit 34 is depressurized at 4.5 kPa up and down, and the third sizing is performed. Inserted into the plate. The total amount of the third sizing plate water supply, the amount of water supplied from the two rows of water supply slits 50G, the amount of discharge from the drainage slits 40G, and the carry-in rate of cooling water to the second sizing plate side were the same as in Example 1.
Next, the hollow plastic sheet was molded under the same conditions as in Example 1 except that the degree of pressure reduction was 3.3 kPa on the front side and 2.4 kPa on the rear side as conditions for the second sizing plate and the vacuum box. The manufacturing conditions and evaluation results are summarized in Table 1.

Example 3
Instead of the third sizing plate 70 of the second embodiment, the first sizing plate 2 used in the first embodiment having the water supply / drainage block 10 shown in FIG. 8 and the indirect cooling sizing former 30 used in the second embodiment are combined. Except for sizing, hollow plastics of the same type were molded in substantially the same manner as in Example 1. The manufacturing conditions and evaluation results are summarized in Table 1.

Example 4
In Example 3 which combined the indirect cooling sizing former and the first sizing plate, A-5-100N having a thickness of 5 mm and a basis weight of 1000 g / m 2 was manufactured at a speed of 5.7 m / min. A hollow plastic was molded in substantially the same manner as in Example 3 except that the degree of vacuum in the indirect cooling sizing former and the vacuum box was higher than that in Example 3. The manufacturing conditions and evaluation results are summarized in Table 1.

Comparative Example 1
In Example 2, a hollow plastic sheet was molded under substantially the same conditions as in Example 2 except that only the third sizing plate was used without using the indirect cooling sizing former.
Since the amount of cooling water cannot be controlled uniformly in the width direction, temperature spots occur in the width direction of the surface of the hollow plastic sheet at the entrance of the temperature third sizing plate, and a polka dot pattern with a diameter of 1 to 3 mm and a height of 20 to 100 μm is random. The appearance was remarkably poor and continuous production was difficult. The manufacturing conditions and evaluation results are summarized in Table 1.

The sizing device for hollow plastic sheets of the present invention is a device capable of sizing a hollow plastic sheet having a thickness of 1.5 to 8 mm and a unit weight of 250 to 2000 g / m ^2. It can be used as a sizing device that can greatly improve the production speed.
The sizing device for a hollow plastic sheet according to the present invention has a process for providing a required number of water supply grooves and drainage grooves in the vicinity of the entrance, a cooling water supply piping process for the water supply grooves, and a suction groove in the sizing plate. Since the sizing plate body can be constructed by machining to the extent of processing, the manufacturing cost of the sizing plate can be greatly reduced, and it can be used as an extremely practical hollow plastic sheet sizing device.
Furthermore, the sizing device for a hollow plastic sheet of the present invention cools the melt-extruded hollow plastic sheet by spraying the cooling water from the water supply slit and the cooling water directly onto the sizing plate, so that the cooling efficiency is high, It can be used as a sizing device for hollow plastic sheets that can reduce cooling costs.
In addition, the method for producing a hollow plastic sheet of the present invention forms the hollow plastic sheet using the sizing device of the present invention, so that compared with the case of using a conventional device,
Sizing is possible even if the thickness is greater and the weight is higher, and the speed can be increased by a factor of about 2 if the thickness is higher than that of the conventional one. In particular, it can be used as a highly productive method for producing a high-weight hollow plastic sheet suitable as a protective material or cushioning material.

D Die S Hollow plastic sheet L Liner R Rib Br Fraction point WL Device width (T direction width)
DESCRIPTION OF SYMBOLS 1 Sizing apparatus for hollow plastic sheets 1A Sizing apparatus for hollow plastic sheets of 1st aspect 1B Sizing apparatus for hollow plastic sheets of 2nd (3rd) aspect 2 1st sizing plate 3 2nd sizing plate 4 Drainage slit 4G Drainage groove 5 Water supply slit 5G Water supply groove 6 Pressure reducing box 7 Front pressure reducing box 8 Rear pressure reducing box 10 First pressure reducing section 11 Second pressure reducing section 13 Suction slit 14 Cooling water spray device 15 Pressure reducing means 16 Pressure adjusting means with solenoid valve 20 Water supply / drainage block 21 For connection Bolt 22 Opening 23 Cooling base plate 24 Take-up machine 30 Indirect cooling sizing former 31 Indirect cooling sizing former block 32 Indirect cooling sizing former block 33 Cooling surface 35 Suction duct 36 Cooling water flow pipe 37 Suction hose (tube) connection hole 40 Drainage groove 50 Water supply groove 51 Decompression line 52 Cooling pipe 70 Third sizing plate 80 Water supply hose (tube) connection port 100 First depressurization section 150 Sizing device 151 Negative pressure line 152 Cooling water circulation line 200 Water supply / drainage block

Claims (13)

The first sizing plate that is in contact with the melt-extruded hollow plastic sheet and the first decompression section composed of the water supply / drainage block, and is connected to the first sizing plate to surround the second sizing plate provided on the take-up side. A sizing device for a hollow plastic sheet comprising a second vacuum section composed of a vacuum box,
In the first sizing plate, water supply slits and drainage slits are alternately arranged in the width direction of the plate,
The water supply / drainage block is provided with a water supply groove facing the water supply slit and connected to the water supply means, and a water supply groove facing the drainage slit and connected to the drainage means, and the water supply groove is made of a hollow plastic sheet. In order to supply water uniformly in the width direction of the plate according to the width dimension, a water supply means that is divided into a plurality of parts, the drainage groove is provided with a drainage means for draining uniformly in the width direction of the plate,
The second sizing plate is provided with a suction slit in the width direction of the plate, the decompression box has a cooling water spray device, and an opening for decompression and drainage,
Furthermore, the first sizing plate and the second sizing plate are formed from a pair of upper and lower plates,
A sizing device for a hollow plastic sheet. An indirect cooling sizing former that is in contact with the melt-extruded hollow plastic sheet, a first decompression section composed of a third sizing plate and a water supply / drainage block, and connected to the third sizing plate, provided on the take-up side A sizing device for a hollow plastic sheet comprising a second decompression section composed of a decompression box surrounding a second sizing plate,
The indirect cooling sizing former comprises a cooling surface and suction means on the contact surface side with the hollow plastic sheet,
In the third sizing plate, water supply slits and drainage slits are alternately arranged in the width direction of the plate,
In the water supply / drainage block, a water supply groove facing the water supply slit and connected to the water supply means, and a drainage groove facing the drainage slit and connected to the water discharge means are arranged,
The second sizing plate is provided with a suction slit in the width direction of the plate, the decompression box has a cooling water spray device and an opening for decompression and drainage,
Furthermore, an indirect cooling sizing former, a third sizing plate, and a second sizing plate are each formed in a pair of upper and lower sides,
A sizing device for a hollow plastic sheet. An indirect cooling sizing former in contact with the melt-extruded hollow plastic sheet, a first decompression section composed of a first sizing plate and a water supply / drainage block, and the first sizing plate are connected to the take-up side. A sizing device for a hollow plastic sheet comprising a second decompression section composed of a decompression box surrounding a second sizing plate,
The indirect cooling sizing former comprises a cooling surface and suction means on the contact surface side with the hollow plastic sheet,
The water supply / drainage block is provided with a water supply groove facing the water supply slit and connected to the water supply means and a water supply groove facing the drainage slit and connected to the water discharge means, and the water supply groove has a width of the hollow plastic sheet. Depending on the dimensions, the water supply means can be divided into a plurality of parts in the width direction of the plate and supplied uniformly, and the drainage groove has a drainage means that can discharge water uniformly in the width direction of the plate,
The second sizing plate is provided with a suction slit in the width direction of the plate, the decompression box has a cooling water spray device and an opening for decompression and drainage,
Furthermore, the indirect cooling sizing former, the first sizing plate, and the second sizing plate are formed in a pair of upper and lower sides,
A sizing device for a hollow plastic sheet.   4. The hollow plastic according to claim 1, wherein the first sizing plate has a width of one section of a water supply groove divided into a plurality of sections in the width direction of the plate according to a width dimension of the hollow plastic sheet, and is 100 to 300 mm. Sheet sizing device.   The indirect cooling sizing former includes a metal block capable of circulating water therein, and a slit formed in the metal block so as to open on the side facing the hollow plastic sheet, and a duct portion communicating with the slit 5. The hollow plastic sheet according to claim 2, further comprising a connection plug that leads to a decompression line disposed in the duct portion in the width direction of the plate according to the width dimension of the hollow plastic sheet. Sizing device.   The contact surface with the hollow plastic sheet in the first, second and third sizing plates and the indirect cooling sizing former is formed of a metal plate having wettability with a contact angle of 65 ° or less. A sizing device for a hollow plastic sheet according to any one of the above.   7. The hollow plastic sheet according to claim 6, wherein the metal plate having wettability with a contact angle of 65 ° or less is formed of brass, copper alloy, or aluminum whose surface is plated or anodized, or has a satin finish. Sizing device.   The sizing device for a hollow plastic sheet according to any one of claims 1 to 7, wherein the decompression box is divided into a plurality of parts. The thickness of the hollow plastic sheet molded object, 1.5~8mm, and unit weight hollow plastic sheet sizing device according to claim 1 is of the 250~2000g / m ^2.   A method for producing a hollow plastic sheet using the sizing device for a hollow plastic sheet according to claim 1, wherein the hollow plastic sheet comprising a parallel liner portion and a plurality of ribs between the liners is melt-extruded and then A pair of first sizing plates leads to a water supply slit provided in the first sizing plate and connected to a water supply groove connected to the water supply means. A part of the cooling water is drained by a negative pressure from a drain slit provided in the first sizing plate and connected to a drain groove connected to the drainage means, and a water film is provided between the sizing plate and the hollow plastic sheet. In the state that is formed, lead to the second sizing plate connected to the first sizing plate, The hollow plastic sheet is slid to the upper and lower sizing plates by negative pressure from the suction slit provided on the two sizing plates, and cooling water is sprayed on the second sizing plate to cool and solidify the hollow plastic sheets. A method for producing a hollow plastic sheet, comprising: A method for producing a hollow plastic sheet using the sizing apparatus for a hollow plastic sheet according to claim 2, wherein after the hollow plastic sheet comprising a parallel liner portion and a plurality of ribs between the liners is melt-extruded, Lead to a pair of indirect cooling sizing formers, while sucking the upper and lower liner parts by suction means, contact the cooling surface of the indirect sizing former to cool the surface of the liner part,
Next, led to the third sizing plate, while supplying cooling water to the upper and lower surfaces of the hollow plastic sheet from the water supply slit provided in the third sizing plate, while draining a part of the cooling water by negative pressure by the drain slit, With a water film formed between the sizing plate and the hollow plastic sheet, the hollow plastic sheet is guided to the second sizing plate connected to the third sizing plate and negative pressure from the suction slit provided in the second sizing plate. The hollow plastic sheet is cooled and solidified by spraying cooling water onto the second sizing plate and sliding the glass toward the upper and lower sizing plates. A method for producing a hollow plastic sheet using the sizing device for a hollow plastic sheet according to any one of claims 3 to 9, wherein the hollow plastic sheet comprises parallel liner portions and a plurality of ribs between the liners. After being melt extruded, it is led to an indirect cooling sizing former having a suction means and a cooling surface on the contact surface side of the hollow plastic sheet, the surface of the hollow plastic sheet is precooled, and the indirect cooling sizing force from the first sizing plate side. The direct cooling water that flows back or leaks to the mer side is discharged by the suction means of the indirect cooling sizing foamer, leading to the first sizing plate,
The cooling water is supplied to the upper and lower surfaces of the hollow plastic sheet uniformly (substantially) in the width direction of the sheet from the water supply slit connected to the water supply means connected to the water supply means of the water supply / drainage block, and is provided on the first sizing plate. A portion of the cooling water is drained by a negative pressure from a drain slit connected to a drain groove connected to the first sizing plate in a state where a water film is formed between the sizing plate and the hollow plastic sheet. The hollow plastic sheet is slid to the upper and lower sizing plates by the negative pressure from the suction slit provided on the second sizing plate, and the cooling water is sprayed on the second sizing plate to create a hollow Production of hollow plastic sheets characterized by cooling and solidifying plastic sheets Method.   A hollow plastic sheet obtained by the method for producing a hollow plastic sheet according to claim 10.

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