JP2012051179A - Apparatus and method for manufacturing foamed sheet of polystylene-based resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing a foamed sheet of a polystylene-based resin, the apparatus including a correction member helpful for correction of angular edge portions.SOLUTION: The apparatus is for manufacturing the foamed sheet of the polystylene-based resin. A correction device 5 includes the correction member 50 with a cross-sectionally U-shaped groove 55 capable of housing a width direction end portion of the foamed sheet S of the polystylene-based resin, wherein the correction member 50 is included by bringing a curved surface portion 5a formed in a bottom portion of the groove 55 into contact with the edge portion to be able to make the correction.

Description

  The present invention relates to a production facility for a polystyrene resin foam sheet and a method for producing a polystyrene resin foam sheet. More specifically, the present invention includes an extruder and a circular die having an annular die slit. The circular die is attached to the tip of the extruder to extrude and foam the resin composition to continuously form a cylindrical foam. The cylindrical foam is expanded to form a strip-shaped foam sheet. A polystyrene-based resin foam sheet manufacturing facility further comprising a cutting device for providing a continuous cut along the extrusion direction in the foam so as to be formed, and a circular die attached to the tip of the extruder A polystyrene resin composition is extruded and foamed from an annular die slit to form a cylindrical foam and the cylindrical shape. The method for producing a polystyrene resin foam sheet to form a strip of polystyrene-based resin foam sheet to expand the foam.

Conventionally, resin foam sheets based on polystyrene resins are widely used as raw materials for thermoformed products such as food trays.
This polystyrene-based resin foam sheet is usually manufactured by continuous extrusion foaming of a polystyrene-based resin composition, and once in a state called a raw fabric roll in which a long strip is wound into a roll. After that, it is used for molding.

  More specifically, a polystyrene resin composition is melt-kneaded with a foaming agent or the like in an extruder, and the melt-kneaded product is extruded and foamed from an annular die slit of a circular die attached to the tip of the extruder to form a cylinder. A continuous foam is formed, and after cooling the foam from the inside with a cooling mandrel, a continuous cutting along the extrusion direction is made with a cutting device and then expanded, and the resulting polystyrene foam foam is obtained. The said original fabric roll is produced by winding up a sheet | seat in roll shape.

  At this time, a wide raw roll is produced by providing a cut only at one location in the circumferential direction of the foam, or two by providing a cut at two symmetrical locations (two locations spaced 180 degrees in the circumferential direction). The production of the original fabric roll is performed.

By the way, the polystyrene resin is generally harder than the polypropylene resin and the polyethylene resin.
Therefore, after providing the notches, the edge portions at both ends in the width direction of the polystyrene resin foam sheet are in a sharp and angular state, and in some cases, convex portions called “burrs” or the like are formed on the edge portions. Have been.
If such an edge portion is left as it is, the polystyrene resin foam sheet edge fed out from the outside of the raw roll when the polystyrene resin foam sheet is subjected to thermoforming, the polystyrene wound on the inside There is a risk that the surface of the resin-based resin foam sheet may come into contact with the surface and be damaged, and in some cases, an operator who handles the raw roll may injure the fingertip or the like.
For this reason, the conventional polystyrene-based resin foam sheet requires careful work when handling it.

In contrast to this, for example, the following Patent Document 1 describes that the edge portion is crushed and corrected to a rounded state.
Specifically, Patent Document 1 has a shape in which two cones are opposed to each other and connected at the top, and has a wide-angle cross section between a slope on one cone side and a slope on the other cone side. It is described that a member in which a V-shaped groove is formed is used as a member (correcting member) for correcting by crushing an edge portion of a polystyrene resin foam sheet (FIGS. 1 and 2 of Patent Document 1). Etc.).

Further, in Patent Document 1 below, as a method of using the correction member having the V-shaped groove, a force is applied in a direction in which the width direction end portion (side edge portion) of the polystyrene resin foam sheet enters the groove depth. In addition, by pressing the correction member against the side edge of the polystyrene resin foam sheet, the edge on one side of the polystyrene resin foam sheet is brought into contact with the slope on one cone side and the edge on the other side is A method is described in which the edge portion is crushed by abutting against the inclined surface on the other cone side.
However, if such a straightening member is used, it is difficult to expect a sufficient straightening effect, and there is a possibility that a partially angular edge portion may remain on the polystyrene resin foam sheet.

  That is, conventionally, there has not been provided a correction member that can be expected to have a sufficient effect for eliminating the angular edge portion, and it is difficult to obtain a polystyrene-based resin foam sheet that is easy to handle. Yes.

JP 2000-239427 A

  In view of the above problems, the present invention provides a manufacturing facility for a polystyrene resin foam sheet provided with a correction member effective for correcting an angular edge portion, and thus manufactures an easily handled polystyrene resin foam sheet. It is an object of the present invention to provide a method for producing a possible polystyrene-based resin foam sheet.

  In order to solve the above-described problems, the present inventors have conducted intensive studies. As a result, the correction member described in Patent Document 1 is brought into contact with the edge portion of the polystyrene resin foam sheet. Since the angle of the inclined surface is substantially constant from the inlet portion of the groove toward the back of the groove (bottom of the groove), the side edges of the polystyrene resin foam sheet are straight toward the depth direction of the groove. While there is no problem during the state (see FIG. 4 (a)), if an angle is given (see FIG. 4 (b)), the edge part on one side of the polystyrene-based resin foam sheet is the inclined surface. It has been found that the crushing effect of the edge portion is drastically reduced when the angle in contact with the surface becomes shallow.

  And when earnestly examining the suppression method of such a phenomenon, the shape of the groove that accommodates the side edge portion of the polystyrene resin foam sheet has a U-shaped cross section, and the curved surface formed at the bottom of the groove Even if the side edges of the polystyrene-based resin foam sheet are inclined with respect to the depth direction of the groove by abutting the edge, the contact between the edge and the inner wall surface of the groove hardly changes. The present invention has been completed by finding that the crushing effect is easily maintained.

  That is, the present invention relating to a production facility for a polystyrene resin foam sheet includes an extruder and a circular die having an annular die slit, and a polystyrene foam is obtained by extrusion foaming a polystyrene resin composition. The circular die is attached to the tip of the extruder to continuously form a foam, and the cylindrical foam is expanded to form a strip-shaped polystyrene-based resin foam sheet. A cutting device for providing continuous incisions along the direction, and a correcting device for crushing and correcting edges at both ends in the width direction of the polystyrene resin foam sheet after the incisions are provided. It is the manufacturing equipment of the polystyrene-type resin foam sheet currently used, Comprising: In the said correction apparatus, the width direction end of the said polystyrene-type resin foam sheet A straightening member having a U-shaped groove capable of accommodating the groove is provided, and the straightening member carries out the straightening by bringing a curved surface portion formed at the bottom of the groove into contact with the edge portion. It is provided in the said correction apparatus so that it may obtain.

  Further, the present invention relating to a method for producing a polystyrene resin foam sheet is a method of continuously forming a cylindrical foam by extruding a polystyrene resin composition from an annular die slit of a circular die attached to the tip of an extruder. An extrusion process for forming the cylindrical foam, a cutting process for providing a continuous cut along the extrusion direction in the foam to form a band-shaped polystyrene resin foam sheet by expanding the cylindrical foam, and the cutting process A method for producing a polystyrene-based resin foam sheet, comprising: crushing edge portions at both ends in the width direction of the subsequent polystyrene-based resin foam sheet and correcting the edge portions, wherein the correction step includes polystyrene-based resin Using a straightening member having a U-shaped groove having a groove width capable of accommodating the widthwise end of the foam sheet, the straightening member is formed at the groove bottom of the straightening member. It is characterized by carrying out the correction on the curved surface portion which are to abut against the edge portion of the polystyrene-based resin foam sheet.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing equipment of the polystyrene-type resin foam sheet provided with the correction member effective in correction | amendment of the square edge part is provided, and manufacture of the polystyrene-type resin foam sheet which can manufacture an easy-to-handle polystyrene resin foam sheet A method may be provided.

FIG. 1 is an equipment configuration diagram showing an embodiment of equipment for producing a polystyrene resin foam sheet. FIG. 2 is a plan view showing a state where the correction apparatus is installed as viewed from above. FIG. 3A is a schematic cross-sectional view showing a cross-sectional view taken along line X-X ′ in FIG. 2, and FIG. 3B is an enlarged view of a broken-line area Y in FIG. FIG. 4 is a diagram illustrating a use situation of a conventional correction device.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a production facility for polystyrene resin foam sheets according to the present embodiment, and FIG. 2 is a plan view showing a state in which an installation state of a correction device is viewed from above.
3A is a schematic cross-sectional view showing a cross-sectional view taken along the line XX ′ in FIG. 2, and FIG. 3B is an enlarged view of the broken-line area Y in FIG. It is.

As shown in this figure, the production equipment for polystyrene resin foam sheets according to this embodiment includes a tandem extruder 1 as an extruder for melt-kneading a polystyrene resin composition containing a foaming agent. Is provided.
A circular die 2 for extruding the polystyrene-based resin composition in a foamed state to form a cylindrical foam FB is attached to the tip of the tandem extruder 1.
Further, in the manufacturing facility, the foam FB discharged in a cylindrical shape from an annular die slit opened on the front surface of the circular die 2 is cooled from the inner surface side, and the foam is expanded to have a predetermined diameter. A cooling mandrel 3 for forming a cylindrical shape having a size is provided.

  In the manufacturing equipment for polystyrene resin foam sheets according to this embodiment, a cylindrical foam FB cooled by the cooling mandrel 3 is developed to form a strip-shaped polystyrene resin foam sheet (hereinafter simply referred to as “foam sheet”). A cutting device 4 for providing continuous cuts in the extrusion direction in the foam FB, and edge portions SE at both ends in the width direction of the foam sheet S after the cuts are formed. Is further provided with a correction device 5 for crushing and correcting to a rounded state.

The tandem extruder 1 is formed by connecting two extruders, an upstream extruder 1a and a downstream extruder 1b, and a material for forming a polystyrene resin foam sheet is input to the upstream extruder 1a. There are provided a hopper 11 and a gas introduction part 12 for supplying a foaming agent such as a hydrocarbon from the gas supply device 15 into the cylinder.
The downstream die 1b is equipped with the circular die 2 in which an annular die slit (resin discharge port) is formed.

The circular die 2 is configured to extrude a resin composition melt-kneaded by an extruder toward a cooling mandrel 3 installed in front of the circular die 2 in a foamed state, and the cooling mandrel 3 includes It has a cylindrical shape larger in diameter than the circular die itself, and the outer peripheral surface thereof can be brought into sliding contact with the inner surface of the cylindrical foam FB extruded from the circular die 2 to cool the foam FB from the inside. It is equipped as such.
In the present embodiment, the circular die 2 and the cooling mandrel 3 are provided such that the approximate center of the die slit is positioned on an extension line obtained by extending the cylindrical central axis of the cooling mandrel 3. ing.
Therefore, the foam FB ′ between the circular die 2 and the cooling mandrel 3 is expanded in diameter substantially uniformly from the circular die 2 toward the cooling mandrel 3.

The cutting device 4 has a cutting blade CT for making a pair of left and right cuts into the cylindrical foam FB on the downstream side of the cooling mandrel 3, and the manufacturing equipment for the foam sheet S in this embodiment includes a cut The roller 91 for expanding the cylindrical foam FB, which is divided into two in the upper and lower directions into a flat sheet, and the expanded foam S, the upper roll UR and the lower roll LR. A take-up roller 92 is provided for taking up as an original roll.
The take-up roller 92 has a speed adjusting mechanism so that the foam sheet S can be taken up at a constant take-up speed while the foam FB is continuously pushed out from the die slit of the circular die 2. .
The cylindrical foam FB is drawn to the downstream side when the foam sheet S is taken up by the take-up roller 92, and is automatically supplied to the cutting device 4 and continuously by the cutting blade CT. A cut will be made.

From this, in the manufacturing facility of the present embodiment, the side end surface of the foam sheet S after passing through the cutting device 4 and being developed in a flat state becomes a cut end by the cutting blade CT.
The angle formed between the foam sheet-side end surfaces of the foam sheet and the both surfaces of the foam sheet is generally a right angle, and the corners (edge portions SE) at both ends of the foam sheet are in an angular state. .
Therefore, the correction device 5 is provided to correct the edge portion SE in a rounded state.
In the present embodiment, the correcting device 5 is provided so that the edge portion can be corrected after being developed into a flat sheet by the roller 91 and before being wound by the winding roller 92.
In this embodiment, as shown also in FIG. 2, in order to correct the edge portions SE at both ends in the width direction of the foam sheet S, a set of two correction devices 5 for one foam sheet S. The correction devices 5 are disposed at both ends of the foam sheet S in a state of being substantially symmetrical with the foam sheet S interposed therebetween.
Moreover, in this embodiment, two sets (four in total) are provided so that the edge SE can be corrected in both the foam sheet wound around the upper roll UR and the foam sheet wound around the lower roll LR. The straightening device 5 is provided.

The straightening device 5 includes a grooved pulley 50 that can rotate around an axis as a straightening member for straightening the edge portion SE, and the grooved pulley 50 has its rotational axis in the vertical direction. The straightening device 5 is provided in a state where the straightening device 5 extends.
The straightening device 5 has a support substrate 51 made of a plate-like body standing in the vertical direction as a member for supporting the grooved pulley 50, and one end fixed to the support substrate 51. It has four pin members 52 extending in the horizontal direction on one surface side of the support substrate 51.
These pin members 52 are composed of four round bars having the same length, and are attached to the support substrate 51 so as to be positioned at respective vertices when a horizontally long rectangle is drawn on the support substrate 51. .
In other words, the four pin members 52 are arranged separately in two at the top and at the bottom, and each two are attached to the support substrate 51 with a substantially equal distance in the horizontal direction.

The correction device 5 is further provided with a support member 53 that directly supports the grooved pulley 50 as a support for supporting the grooved pulley 50.
The support member 53 has a length longer than the distance in which the pin member 52 is separated in the horizontal direction, and two through holes into which the two pin members 52 that are separated in the horizontal direction can be respectively inserted. It is formed in the shape of a square bar having
One of the two support members 53 is inserted between the two pin members 52 by inserting the upper two pin members 52 through the through holes, respectively, and the other is also the same. The lower pin member 52 is suspended.

The two support members 53 are for vertically supporting the rotary shaft 5x of the pulley 50 with grooves, and the upper end and the lower end of the rotary shaft 5x are fixed at the center in the length direction. Has been.
The support member 53 is prevented from coming off from the pin member 52 by a stopper 54 attached to the tip of the pin member 52 inserted through the through hole. The correction device 5 is provided so as to be movable between the two.

The correction device 5 in the present embodiment further includes a coil spring SP that is externally fitted to the pin member 52 between the support member 53 and the support substrate 51, and the natural nature of the coil spring SP. The repulsive force of the coil spring SP can be applied to the support member 53 by bringing the support member 53 and the support substrate 51 closer to each other than the length.
Therefore, the correction device 5 in the present embodiment can adjust the repulsive force of the coil spring SP by adjusting the relative position with the foam sheet S, and can adjust the degree to which the edge portion SE is crushed. .

As described above, in the polystyrene resin foam sheet manufacturing apparatus according to this embodiment, two correction apparatuses 5 are provided so as to form a pair with the foam sheet S interposed therebetween.
Therefore, in this embodiment, by adjusting the distance between the correction devices, the relative position between the correction device 5 and the foam sheet S is adjusted, and the degree of correction of the edge portion SE is adjusted.

The pulley 50 with a groove has a flat disk-shaped pulley body 50 'that can rotate around the rotation shaft 5x, and the pulley body 50' has a groove 55 that circulates along the outer periphery thereof. Yes.
That is, the groove 55 provided in the grooved pulley 50 is an annular groove having an annular shape around the rotation shaft 5x.

  The grooved pulley 50 accommodates the end of the foam sheet S in the width direction in the groove 55, and at the groove bottom part, the inner wall surface and the edge part SE are brought into contact with each other to round the edge part SE. It functions as a straightening member for holding.

In order to stably exhibit such a function as a correction member, it is important that the annular groove is formed in a U-shaped section in the grooved pulley 50.
More specifically, the groove 55 has a groove depth direction from the opening on the outer periphery of the pulley body 50 ′ toward the rotary shaft 5 x so that the inner wall faces the groove in a substantially parallel state at a portion close to the opening. At the groove bottom near the rotation shaft 5x while having a constant width, a curved surface 5a having a circular arc shape in the U-shaped cross section is formed.

By providing the bottom surface with the curved surface portion 5a in which the inner wall surface of the groove 55 has an arc shape in this way, the edge portion SE of the foam sheet S accommodated in the groove 55 is crushed by the curved surface portion 5a. Thus, it is corrected to a rounded shape along the curved surface portion 5a.
In addition, the correction device 5 of the present embodiment is such that even if the foam sheet S is inclined inside the groove 55, the contact between the groove inner wall and the edge portion only moves on the arc, and these contacts are made. It is comprised so that a state may not change a lot.

  The pulley 50 with a groove is provided in a state of being rotatable around an axis, and the groove 55 is an annular groove having an annular shape around the axis, so that the foam sheet S is taken up. The pulley body 50 'can be rotated as it moves in the direction, and the edge portion SE can be continuously corrected during the rotation.

The grooved pulley 50 can hold the foamed sheet S in a stable state because the groove width is substantially constant in a fixed section from the opening on the outer periphery of the pulley body 50 ′ toward the rotating shaft 5 x.
In addition, when the thickness of the foam sheet S is thin with respect to the groove width, the foam sheet may be inclined in the groove.
However, since the groove 55 is formed so that the cross-sectional shape is U-shaped and the bottom is round, even if the foam sheet S is inclined to some extent, the contact state between the edge SE and the bottom of the groove 55 Does not change significantly.

However, if the foam sheet S is excessively inclined inside the groove, there is a possibility that the correction state of the edge portion on the one surface side of the foam sheet S and the correction state of the edge portion on the other surface side are different.
Further, since the foam sheet S has a certain level of cushioning properties, even when the thickness of the foam sheet S in the natural state exceeds the groove width to some extent, the end portion of the foam sheet is accommodated in the groove 55. However, if the foam sheet S is thicker than the groove width, it becomes difficult to make the edge SE strongly contact the curved surface a of the groove bottom, and the edge SE can be rounded. It becomes difficult.
From such a viewpoint, the thickness of the foam sheet S with respect to the width of the groove is preferably 50% to 95%, and more preferably 65% to 85%.

  Further, the depth of the groove 55 (depth to the bottom) depends on the thickness of the foam sheet to be corrected, but in a foam sheet having a general thickness of about 0.5 mm to 3.5 mm, The groove depth is preferably 2 mm to 30 mm, and more preferably 5 mm to 15 mm.

  Furthermore, it is preferable that the curved surface portion 5a has an arc shape having a radius of 0.5 mm to 1.0 mm.

  The radius of the grooved pulley 50 (the distance from the axial center to the outer periphery of the grooved pulley 50) is usually 30 mm to 110 mm.

In the present embodiment, an example is given in which the grooved pulley 50 as described above is provided in a state of being rotatable around an axis as a correction member in that the edge portion can be smoothly corrected. For example, a straightening member having the same shape as the grooved pulley 50 is arranged in a fixed state so as not to rotate, and the edge portion which is squared by passing the end of the foam sheet through the groove having a U-shaped cross section. You may make it round by correcting.
In the case of fixed arrangement, the correction member having a U-shaped groove does not need to be an annular groove like a grooved pulley. It is also possible to use a plate-like body in which a groove is formed as a correction member.

  Moreover, this invention is not limited to the said illustration about the structure of correction apparatuses other than this correction member, and structures other than a correction apparatus.

Next, a method for producing a polystyrene resin foam sheet using the above production equipment will be described.
In this embodiment, a polystyrene resin foam sheet is produced by performing the following steps.
That is, in this embodiment,
(1) In order to adjust the material necessary for the production of the polystyrene resin foam sheet of the present embodiment, the polystyrene resin is used as a base resin, and the necessary ingredients are added to the raw material of the polystyrene resin foam sheet. The blending process to be adjusted,
(2) An extrusion process in which the adjusted raw material is extruded and foamed from an annular die slit of a circular die attached to the tip of an extruder to continuously form a cylindrical foam,
(3) A cutting step of providing a continuous cut along the extrusion direction in the foam to expand the cylindrical foam to form a band-shaped foam sheet,
(4) An unfolding step of unfolding the cylindrical foam provided with the cut into a flat sheet,
(5) A straightening step in which the edge portions at both ends in the width direction of the foam sheet provided with the notches are crushed to correct the edge portions (6) A polystyrene resin foam sheet with the edge portions straightened is wound into a roll shape The winding process to take is implemented and a polystyrene-type resin foam sheet is produced.
Below, each process is demonstrated in detail.

(1) Blending step This blending step is a step of adjusting the blending of the polystyrene resin composition that is the raw material of the foam sheet, and in the same manner as in the production of a general polystyrene resin foam sheet, a meter and kneading It can be implemented using a device such as a machine.
As an example, a method of dry blending a polystyrene-based resin and a masterbatch containing various compounding agents can be mentioned.
Moreover, the method of producing the pellet which contains all the polystyrene-type resin and other compounding agents using general kneading apparatuses, such as a kneader and a biaxial kneader, is mentioned, for example.

  The polystyrene resin is not particularly limited, and examples thereof include styrene, α-methyl styrene, vinyl toluene, ethyl styrene, i-propyl styrene, t-butyl styrene, dimethyl styrene, bromostyrene, chlorostyrene, and the like. Examples thereof include homopolymers of styrene monomers or copolymers obtained by combining a plurality of these.

  The polystyrene resin may be a copolymer of the above styrene monomer and a vinyl monomer copolymerizable with the styrene monomer. For example, alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cetyl (meth) acrylate, (meth) acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl fumarate In addition to ethyl fumarate, bifunctional monomers such as divinylbenzene and alkylene glycol dimethacrylate are exemplified.

  The polystyrene resin composition may contain a resin component other than the polystyrene resin. For example, poly (2,6-dimethylphenylene-1,4-ether), poly (2,6-diethylphenylene) -1,4-ether), poly (2,6-dichlorophenylene-1,4-ether) and other polyphenylene ether resins may be included.

Furthermore, a polymer type antistatic agent and the like can also be contained.
Examples of the polymer type antistatic agent include ionomers such as polyethylene oxide, polypropylene oxide, polyethylene glycol, polyester amide, and polyether ester amide, quaternary ammonium salts thereof, polyether-polystyrene block copolymers (polyether block) And polystyrene block copolymer).

  In addition to such resin components, examples of components to be included in the polystyrene-based resin composition include functional components such as low molecular weight antistatic agents and components relating to foaming such as cell nucleating agents for foaming. Can do.

  Examples of the low molecular weight antistatic agent include an anionic surfactant such as an alkylbenzene sulfonate, for example, sodium dodecylbenzene sulfonate, and a low molecular charge such as other surfactant or alkali metal salt. An inhibitor.

  Examples of the component relating to foaming include a bubble nucleating agent for forming bubbles together with the foaming agent introduced from the gas introduction unit 12, or a compound particle that generates gas by thermal decomposition.

The bubble nucleating agent (bubble adjusting agent) is not particularly limited as long as it is generally used as a bubble nucleating agent. For example, talc, mica, silica, diatomaceous earth, aluminum oxide, titanium oxide, oxidation Particles such as zinc, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, potassium carbonate, calcium carbonate, magnesium carbonate, potassium sulfate, barium sulfate, inorganic compounds such as glass beads, organic compounds such as polytetrafluoroethylene Is mentioned.
In addition, a bubble nucleating agent may be used independently or 2 or more types may be used together.

  As the foaming agent used together with the cell nucleating agent, those conventionally used for extrusion foaming can also be adopted in this embodiment. For example, hydrocarbons such as butane, nitrogen, carbon dioxide, argon, water Etc. can be used.

  Moreover, as the compound particles that generate gas by thermal decomposition, for example, azodicarbonamide, sodium hydrogen carbonate, a mixture of sodium hydrogen carbonate and citric acid, or the like can be used.

Furthermore, as a component constituting this polystyrene-based resin composition, a compounding agent used for forming a general polymer foam molded article can be contained. For example, various stabilizers such as weathering agents and anti-aging agents, lubricants, etc. These processing aids, slip agents, antifogging agents, pigments, fillers and the like can be appropriately contained.
What proportion of these compounding agents are contained in the polystyrene resin composition may be appropriately adjusted according to the final use of the polystyrene resin foam sheet.

(2) Extrusion process
In the extrusion step, the polystyrene resin composition prepared in the previous blending step is melt-kneaded inside the extruder 1, and the circular kneaded product of the circular die 2 attached to the tip of the extruder 1 is melted and kneaded. It can be carried out by extruding and foaming from a die slit to continuously form a cylindrical foam FB.
For example, as a method for carrying out the melt-kneading, in the upstream extruder 1a, a foaming agent is introduced from the gas introduction part 12, and the polystyrene resin composition is heated to a temperature suitable for dispersion of the foaming agent. These are melt-kneaded at a temperature equal to or higher than the melting point of the resin component, and then kneaded at a temperature lower than that of the upstream extruder 1a so as to obtain a melt viscosity suitable for extrusion foaming in the downstream extruder 1b. The method etc. are mentioned.

  In addition, as a method of forming the cylindrical foam FB, a melt-kneaded product that has been temperature-adjusted so as to have an appropriate melt viscosity by the downstream side extruder 1b is removed from the annular die slit of the circular die 2. A method similar to a conventional method for producing a foamed sheet that is continuously discharged and foamed can be employed.

Thereafter, after cooling the foam FB as necessary, cooling with the cooling mandrel 3 and diameter expansion are performed.
At this time, the cylindrical foam FB expanded in diameter by the cooling mandrel 3 is brought into sliding contact with the outer peripheral surface of the cooling mandrel 3 and sufficiently cooled while passing over the cooling mandrel.

(3) Cutting process This cutting process is to provide a cut for enabling the subsequent expansion process for the cylindrical foam FB expanded in diameter by the cooling mandrel 3.
In the present embodiment, the cutting blades CT are provided on the left and right sides of the cooling mandrel 3, respectively, and two cuts that are 180 degrees apart from each other in the circumferential direction are continuously formed in the cylindrical foam FB. The cylindrical foam FB can be divided into upper and lower parts, and the like.

(4) Unfolding step This unfolding step is a step in which the cylindrical foam FB in which cuts are formed in the cutting step is expanded in the width direction to form a flat sheet.
This step is performed on the outer peripheral surface of the two rollers 91 provided at substantially the same height as the upper end of the cooling mandrel 3 and substantially the same height as the lower end using the tension generated by the winding by the winding roller 92. It can be carried out by, for example, a method of spreading the polystyrene resin foam sheet along.

This will be further explained. Even after the cut is provided by the cutting blade CT on the downstream side of the cooling mandrel 3, the two upper and lower foam sheets have a semicircular shape in a cross section perpendicular to the extrusion direction for a while. However, as it approaches the roller 91 side, it is expanded to the left and right in the width direction, and is eventually wound around the outer peripheral surface of the roller 91 to be developed into a flat sheet.
In this unfolding step, the foamed sheet S wound around the outer peripheral surface of the roller 91 and unfolded into a flat sheet is wound around another roller 91 to flatten the foamed sheet.

(5) Straightening process In the cutting process, when a cut is not provided with certainty, troubles occur in the development process and the like, and therefore a cutting blade with a sharp edge is usually used.
Therefore, the corner portion (edge portion) of the cut end is in a sharp state.
In the present embodiment, a correction process is performed in order to facilitate handling of the foam sheet by crushing the edge portion.

Further, the correction process can be performed using the correction device 5 as described above.
That is, it can be implemented by the correction device 5 including the grooved pulley 50 (correction member) including the groove 55 having a U-shaped cross section having a groove width capable of accommodating the widthwise end portion of the foam sheet S.
Specifically, the widthwise ends of the foamed sheets are accommodated in the grooves 55 of the grooved pulleys 50 of the two right and left correction devices 5, respectively, and a certain amount of repulsive force is generated in the coil spring SP of the correction device 5. The position is adjusted so that these correction devices 5 are set.
After that, as the foam sheet S is taken up and moved, the grooved pulley 50 rotates, and the angular edge SE of the foam sheet S is automatically crushed by the curved surface portion 5a at the bottom of the groove. Regions SA in which the edge portions are crushed are continuously formed on both ends in the width direction of the strip-shaped foamed sheet S and on both sides.

At this time, even with the same grooved pulley, for example, with a grooved pulley having a V-shaped groove, it is difficult to stably correct the edge portion.
This will be specifically described with reference to the drawings. As shown in FIG. 4A, the foam sheet Sx is substantially perpendicular to the rotation shaft 5y of the grooved pulley 50x having the V-shaped groove. If it is in contact with the inner wall surface of the groove, there is no great difference in the contact state between the edge portion of the one side S1 of the foam sheet and the edge portion of the other surface side S2, but the groove width is outside. If the foamed sheet is accommodated in the V-shaped groove that widens in the direction, the foamed sheet Sx moves freely within the groove.

  For this reason, for example, as shown in FIG. 4B, when the foam sheet Sx is tilted and abuts against the inner wall surface of the groove and passes through the correction device, the edge portion on the one surface side S1 is crushed to some extent. There is a possibility that the edge portion of the other surface side S2 that can be corrected is almost not crushed.

On the other hand, in the correction device 5 in the present embodiment, the foamed sheet S is perpendicular to the rotation shaft 5x because the grooved pulley 50 has a groove having a U-shaped cross section and the groove width on the outer peripheral side is constant. Since the curved surface portion 5a having an arcuate cross section is formed at the bottom portion to which the foam sheet S is guided and in contact with the edge portion SE, even if the tip of the foam sheet S is inclined and contacted, The state does not change greatly.
Therefore, the correction of the edge portion in this correction process is performed more reliably and with a good finish.

  In addition, in this embodiment, the expansion | deployment process which expand | deploys the foam sheet S to a flat state in the point which arrange | positions the two correction apparatuses facing each other, and is easy to equalize the contact force of the foam sheet S with respect to both correction members. Although the said correction process is implemented after implementing, if necessary, the said correction process can also be implemented with respect to the foam sheet of a cross-sectional semicircle shape before the expansion | deployment process after the said cutting process.

(6) Winding step The polystyrene-based resin foam sheet S with the edge portion corrected in this way is wound into a roll shape by the winding roller 92, and a raw material for producing a thermoformed product such as a food tray. Can be anti-roll.
This winding process can be performed using a winding device with a tension controller that is generally used.
The take-up speed at this time is usually 1 m / min to 70 m / min, although it depends on the thickness and width of the foam sheet to be produced, and further the ability of the extruder.

In the raw roll thus produced, the side end surface of the foam sheet is exposed on the side surface. However, in this embodiment, the edge portion is crushed in a round shape. The possibility of cutting is low, and the raw roll can be easily handled.
In addition, even when the foam sheet is fed out from the raw roll and thermoformed, the generation of chips is suppressed, so that the product is defective due to thermoforming with the chips adhering to the foam sheet. Can be suppressed.
In other words, it is possible to simplify the work of removing chips and improve work efficiency.

  Although not described in detail here, as long as the effects of the present invention are not significantly impaired, conventionally known matters can be adopted in addition to the above-described events regarding the method for producing a polystyrene resin foam sheet.

DESCRIPTION OF SYMBOLS 1 Extruder 2 Circular die 3 Cooling mandrel 4 Cutting device 5 Straightening device 5a Curved surface part 5x Rotating shaft 50 Pulley with groove (correcting member)
55 groove (groove with U-shaped cross section)
CT Cutting blade FB Foam S Polystyrene resin foam sheet

Claims (4)

An extruder and a circular die having an annular die slit are provided, and the circular die is formed at the tip of the extruder to continuously form a cylindrical foam by extruding and foaming a polystyrene resin composition. A cutting device for providing a continuous cut along the extrusion direction in the foam so that the cylindrical foam can be expanded to form a band-shaped polystyrene-based resin foam sheet; A polystyrene resin foam sheet manufacturing facility further equipped with a correction device for crushing and correcting the edge portions at both ends in the width direction of the polystyrene resin foam sheet after the cut is provided,
The straightening device includes a straightening member having a groove having a U-shaped cross section that can accommodate an end in the width direction of the polystyrene resin foam sheet, and the straightening member is formed at the bottom of the groove. A manufacturing equipment for a polystyrene-based resin foam sheet, which is provided in the correction device so that the correction can be performed by bringing the curved surface portion into contact with the edge portion.   In the correction device, the correction member is rotatable about an axis so that the correction member can be rotated in accordance with the movement of the polystyrene-based resin foam sheet in which the end in the width direction is accommodated in the groove. The groove is an annular groove having an annular shape around the axis of the correction member so that the correction can be continuously performed during rotation of the correction member. Equipment for manufacturing polystyrene resin foam sheets.   The said curved surface part is a manufacturing apparatus of the polystyrene-type resin foam sheet of Claim 1 or 2 formed so that the shape in the said U-shaped cross section may become circular arc shape with a radius of 0.5 mm-1.0 mm. An extrusion process for continuously forming a cylindrical foam by extruding and foaming a polystyrene resin composition from an annular die slit of a circular die attached to the tip of an extruder, and developing the cylindrical foam A cutting step for forming continuous cuts in the extrusion direction in the foam to form a strip-shaped polystyrene resin foam sheet, and pressing edges at both ends in the width direction of the polystyrene resin foam sheet after the cutting step A method for producing a polystyrene-based resin foam sheet that performs a correction step of crushing and correcting the edge portion,
In the straightening step, a straightening member having a groove having a U-shaped cross section having a groove width capable of accommodating the widthwise end of the polystyrene resin foam sheet is used, and the curved surface formed at the bottom of the straightening member. A method for producing a polystyrene-based resin foam sheet, wherein the correction is performed by bringing the edge portion of the polystyrene-based resin foam sheet into contact with a portion.

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