JPH0272924A - Cooling device for resin molding - Google Patents

Abstract

PURPOSE:To enable homogeneous molding of a foaming resin molding machine by enabling cooling uniformly, by a method wherein the title device is comprised of divided cooling bodies divided at least into two parts vertically and the divided cooling bodies each are provided with cooling fluid routes which are independent of each other. CONSTITUTION:A mandrel 3 is comprised of the cylindrical first, second and third mandrels 31, 32, 33 obtained by dividing the mandrel 3 into three parts along an extruding direction, respective of which are constituted of divided cooling bodies obtained by dividing into two parts vertically. Cooling pipes 71a, 71b as fluid routes independent of each other respectively are cast into divided cooling bodies 31a, 31b for trim. Similarly, divided cooling bodies 32a, 32b and 33a, 33b are trimed respectively with cooling pipes 72a, 72b and 73a, 73b. cooling capacity of the mandrel 3 can be controlled separately at the top and bottom by controlling a temperature and flow of a feed fluid to the cooling pipes 71a, 71b each separately. A temperature difference at the tip and bottom of a tubular sheet (p) extruded through the mold 2 at a cooling process can be corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a cooling device for resin molding that is used in a foam resin molding machine and cools a sheet of thermoplastic resin extruded from a mold.

<Prior art> Conventionally, a foamed resin molding machine extrudes a material made of thermoplastic resin into a tube shape through a circular slit in a mold using an extruder, cools it using a cooling device, and cools the material on both sides of the tube. Some products are cut at a certain point and wound up as two films or sheets, one on top and one on top.

The above extrusion methods include those that extrude upward, downward, or horizontally, but the extrusion method that extrudes in the horizontal direction (hereinafter referred to as horizontal extrusion method) It is the most commonly used because it is easy to handle.

In general, the cooling method for the above-mentioned horizontal extrusion method is to install a cooling pipe inside a cylindrical body (hereinafter referred to as a mandrel) that is directly connected to the mold, and to bring the outer surface of the mandrel into contact with the inner surface of the tube. A so-called inside mandrel method is used, which cools the tube and regulates the inner diameter of the tube to adjust the molding dimensions. Furthermore, a so-called outside mandrel method is also used in which the inner surface of the mandrel is cooled while being in contact with the outer surface of the tube, and the outer diameter of the tube is regulated to adjust the molding dimensions.

<Problems to be Solved by the Invention> By the way, in the horizontal extrusion method described above, the air near the mold and mandrel is warmed by the heat of the mold and other equipment and rises, causing the ambient temperature surrounding the mold and mandrel to rise. This results in a vertical disparity (approximately 7°C higher on the upper side). This vertical difference in ambient temperature also affects the cooling efficiency of the mandrel, and the molding conditions are different between the upper and lower parts, resulting in a vertical difference in the quality of the molded product. In particular, when a primary product such as the film or sheet is reheated and molded to obtain a secondary product, a noticeable difference occurs in the quality of the secondary product.

For example, in the case of polystyrene, there are two problems: ■ There is a difference in thickness, stretching, etc. between the top and bottom, and ■ Because of the above-mentioned difference in stretching, deep drawing products such as cups and bowls cannot be formed under the same conditions on the top and bottom. In addition, in the case of polyolefin-based products, ■ As with the above-mentioned polystyrene-based products, deep-drawn products cannot be formed under the same conditions on the top and bottom due to the difference in stretching between the top and bottom. Due to the effect of the vertical disparity in stretching, there is a disparity in the thickness of the secondary product, especially for primary products whose expansion ratio is 2 times or less and the thickness after molding is 0.5 mm or less. Wave fringes are likely to occur, and ■ In addition, when the slit width of the mold is widened to prevent the occurrence of wave fringes when the above-mentioned foaming ratio is 2 times or more, the vertical difference in stretching becomes large, so other There was a problem in that even if the molding conditions (temperature and extrusion speed) were changed, good molding could not be performed.

This invention was made in view of the above problems, and
It is an object of the present invention to provide a cooling device for resin molding that can uniformly cool the resin and, in turn, enable a foamed resin molding machine to perform homogeneous molding.

Means for Solving the Problems> The cooling device for resin molding of the present invention to achieve the above object cools the inner surface or In a cooling device for resin molding that cools by contacting the outer surface,
It consists of a divided cooling body divided into at least two upper and lower parts, and is characterized in that each divided cooling body is provided with a mutually independent cooling fluid path.

According to the cooling device for resin molding with the above configuration, the divided cooling body divided into at least two upper and lower parts is provided with mutually independent fluid paths, so that the temperature and flow rate of the fluid supplied to each fluid path can be controlled. By adjusting the above, it is possible to adjust the cooling performance of the upper and lower parts separately, and it is possible to correct the temperature difference between the upper and lower parts during the cooling process of the tubular sheet of thermoplastic resin extruded from the mold.

<Example> Embodiments will be described in detail below with reference to the accompanying drawings showing examples.

Figure 2 is a schematic diagram showing the overall configuration of the foam resin molding machine (^), including the raw material hopper (11) and the foaming agent injection hole (12).
a mold 0 connected to the extruder (1) and having an arcuate slit (not shown);
A mandrel (3) for cooling and sizing connected to the mold (2), a cutter (4) arranged behind the mandrel (3), and a cutter (4) arranged behind the cutter (4). It has a pair of take-up rollers (5) and (6) as its main parts.

In the above-mentioned foamed resin molding machine (A), a foaming agent (b) is added to a thermoplastic resin raw material (S) supplied from a raw material hopper (11) through a foaming agent injection hole (12) in an extruder (1).
At the same time, the raw material (S) is passed through the mandrel (3) through the slit of the mold (2) by the extruder (1).
) is extruded along the outer surface of the tube to form a tubular sheet (p) of a certain size, and then the tubular sheet (p)
Both sides of the sheet are cut by a cutter (4), and the sheet is wound up into two upper and lower sheets around a winding roller (5) and (6).

In addition, the connecting portion 00) between the mold ■ and the mandrel (3) is tapered, and the tube-shaped sheet (p
) has an air blowing hole (not shown) for blowing air into the tubular sheet (p) to inflate it to a predetermined size.

As shown in FIG. 1, the above-mentioned mandrel (3) is a cylindrical first mandrel (
31), second mandrel (32) and third mandrel (
33), each mandrel (31) (32) (3
3) is a divided cooling body (31
a) (31b), divided cooling body (32a) (32b)
, and divided cooling bodies <33a) (33b).

Each divided cooling body (31a) (31b) has a cooling vibe (71a) (71
b) is cast and installed internally, and similarly, the divided cooling bodies (32a) (32b) are equipped with cooling vibes (72a) (
72b) are internally installed, and a divided cooling body (33a)
Cooling pipes (73a) and (73b) are installed inside (33b), respectively. These cooling pipes (71a)
A heat exchangeable fluid such as water, oil, or air is circulated in (71b) to (73b).

In addition, each cooling vibrator (7La) (71b) - (73b)
are arranged in a skewer shape, as shown in FIG.

(8) is a vertical plate for positioning the mandrel, which can be attached at an easy location. (9) is a spacer interposed between the upper and lower divided cooling bodies (31a), (31b)... (see Figure 4), and the spacer (9) is an independent system of cooling vibes (see Figure 4). (not shown), which can independently adjust the temperature, or may be constructed from a heat insulating material that blocks the transfer of heat between the upper and lower divided cooling bodies (31a) (31b)... Also good.

The material of each mandrel (31), (32), and (33) can be metal such as aluminum or iron, or ceramic, and the surface of these can be coated with fluororesin (trademark Teflon, manufactured by DuPont), or For example, a material plated with metal such as Teflock or Nidax (manufactured by Metal Surface Chemical Co., Ltd.) can also be used.

According to this embodiment, the divided cooling body (
3La) (31b)... are equipped with mutually independent cooling pipes (71a) (71b)..., so the temperature of the fluid supplied to each cooling vibe (LLa) (71b)... By adjusting the flow rates separately, the cooling performance of the mandrel (3) can be adjusted separately for the upper and lower parts, and the temperature difference between the upper and lower parts of the tubular sheet (p) extruded from the mold (2) during the cooling process can be reduced. can be corrected. Therefore, the upper and lower homogeneous foam sheets (-finished products)
can be obtained, and as a result, a homogeneous secondary product can be obtained.

Furthermore, along the horizontal direction, a first mandrel (31)
~Since it is divided into the third mandrel (33), by separately adjusting the cooling performance of these mandrels (31) to (33), the horizontal temperature gradient in the cooling process can be appropriately adjusted, Fine adjustments can be made depending on the type of resin, expansion ratio, etc.

Note that the number of divisions of the mandrel (3) in the horizontal direction can be increased or decreased depending on the type of resin, foaming ratio, etc. In addition, there are divided cooling bodies (31) above and below the mandrel (3).
a) Each of (31b)... can also be divided into multiple parts.

Further, a heat insulating material or the like may be interposed between the mandrels (31), (32), and (33), and the spacer (9) does not necessarily need to be provided.

Furthermore, the cross-sectional shape of the cooling pipes (71a), (71b), etc. is preferably a rectangular cross-section because of good cooling efficiency, but other cross-sectional shapes such as a circular cross-section or an elliptical cross-section may be used.

In addition, instead of using cooling pipes as fluid passages, cooling holes formed in the divided cooling body by profile extrusion etc. may be used, or grooves formed on the inner or outer periphery of the divided cooling body may be covered with lids. Various design changes can be made without changing the gist of the invention.

Hereinafter, the present invention will be explained in detail based on experimental examples and comparative examples.

(Leaving space below) Experimental Example I and Comparative Example I> Experimental Example I Using one foamed resin molding machine of the above example and the mandrel (3) as a cooling device for resin molding, raw materials...
A mixture of Dialex HH102 (MI-3,5, catalog value) made by Mitsubishi Monsando as polystyrene and 1 part of talc as a nucleating agent.Blowing agent: 3.2% (weight ratio) based on the above raw materials. ) butane injection extruder (1)...Cylinder temperature 200-95
°C Extrusion amount: 60 kg/H Mold (2): Slit diameter: 200 mm, slit width: 0.7 M Mandrel (3): Water is used as the cooling fluid, as shown in Table 1 above. As shown, the upper and lower cooling pipes (71a
) (71b)..., and set the fluid temperature at the inlet of the upper cooling pipe (7La) (72a) to be lower than that of the lower one.Foam sheet......foaming ratio 11 times, thickness 2.3m
A foamed sheet as the next product is manufactured under the molding conditions of m, and then secondary molding is performed under the thickness ratio shown in Table 1 (secondary product/second product) and the molding conditions to obtain the secondary product. In addition, the elongation and variation in the upper and lower thickness of the secondary product are evaluated as good (indicated by ○ in Table 1) or poor (indicated by × in Table 1).
When we conducted an evaluation test to determine whether

Comparative Example I On the other hand, under the same conditions as Experimental Example I, the cooling pipes (7La) (71b) above and below the mandrel (3) were
By making the fluid temperature at the inlet of the mandrel the same, primary and secondary products were manufactured according to Comparative Example I, simulating a conventional mandrel, and an evaluation test similar to Experimental Example I was conducted. The results were good, but the results were poor regarding thickness variations.

From the evaluation test results of the secondary products obtained in Experimental Example I and Comparative Example I, it was found that when using the conventional mandrel simulated by Comparative Example I, a homogeneous secondary product could not be obtained. and a mandrel (as in Experimental Example I)
3) Upper and lower divided cooling bodies (31a) (31b)...
It was demonstrated that a homogeneous secondary product could be obtained if the cooling performance of the two was adjusted separately.

Experimental Example ■〉 Using the foamed resin molding machine of the above example and the mandrel (3) as a cooling device for resin molding, the raw material... Styron 685 manufactured by Asahi Kasei Industries, Ltd. as polystyrene was used.
(MI-2,1, catalog value), high impact Idemitsu styrene HT51 manufactured by Idemitsu Petrochemical Co., Ltd. (MI-2,1, catalog value)
, catalog value) at a weight ratio of 4:1, and 1 part of talc as a nucleating agent.Blowing agent: 3.5% (weight ratio) of butane based on the above raw materials. Injection extruder (1)...Cylinder temperature 21○~98
°C Extrusion amount 63 kg/H Mold (2)... Slit diameter 200 mm, slit width 0.7 mm Mandrel (3)... Using water as the cooling fluid, as shown in Table 1. In addition to equalizing the fluid temperature at the inlets of the upper and lower cooling pipes (7La) (71b)..., the upper cooling pipe (Ha) (72a)
The flow rate of the foam sheet is set to be higher than that of the lower one.The foam sheet has a foaming ratio of 11.5 times and a thickness of 2.
A foamed sheet as a secondary product was produced under the molding conditions of 4nvn, and then secondary molded under the thickness ratio (secondary product/-secondary product and molding conditions shown in Table 1) to obtain a secondary product. In addition, the elongation of the secondary product and the variation in the upper and lower thicknesses are evaluated as good (indicated by O in Table 1) or poor (indicated by × in Table 1).
When we conducted an evaluation test to determine whether This allows the upper and lower cooling pipes (7
1a) (71b)... Even when supplying fluid at the same temperature to the upper cooling pipe (71a) (
By increasing the flow rate to 72a) than the lower one, the cooling performance of the upper divided cooling bodies (31a) (32a) can be increased compared to the lower one, and as a result, a better secondary product can be obtained. has been proven.

Experimental Example ■ and Comparative Example ■〉 Experimental Example ■ Using the foamed resin molding machine of the above example and the mandrel (3) as a cooling device for resin molding, the raw material...Noblen AD-571 as polypropylene was used. (manufactured by Sumitomo Chemical Co., Ltd., MI-0.6° catalog value), nucleating agent talc 0
．． Foaming agent: Inject 1% (weight ratio) of butane to the above raw materials Extruder (1): Cylinder temperature: 240~ 12
5℃ Extrusion amount 75 kg/H Mold 0...Slit diameter 200mm Slit width 0
．． 5mm mandrel (3)... Water is used as the cooling fluid, and as shown in Table 1, the flow rates of the upper and lower cooling pipes (71a) (71b) are made equal, and the upper cooling pipe (71a) Set the fluid temperature at the inlet of (72a) to be lower than that at the bottom Foam sheet...Foaming ratio: 1.7 times, thickness: 0.9
A foamed sheet as the next product is produced under the molding conditions of 5mm, and then vacuum molded under the thickness ratio (secondary product, /second product) and molding conditions shown in Table 1 to obtain the secondary product. In addition, the elongation of the secondary product was good (in Table 1, O
When an evaluation test was conducted to determine whether the product was good (indicated by x in Table 1) or defective (indicated by x in Table 1), good results were obtained.

Comparative Example ■ On the other hand, under the same conditions as Experimental Example ■, cooling pipes (71a) (71b) above and below the mandrel (3)
By making the fluid temperature at the inlet of the mandrel the same, primary and secondary products were manufactured using Comparative Example ■, which simulates a conventional mandrel, and an evaluation test similar to Experimental Example ■ was conducted. The results showed that the elongation differed depending on the direction and was poor.

From the evaluation test results of the secondary molded products obtained in Experimental Example ① and Comparative Example H, it was found that when using the conventional mandrel simulated by Comparative Example H, a homogeneous secondary product could not be obtained. It has been demonstrated that a homogeneous secondary product can be obtained when the cooling performance of the upper and lower divided cooling bodies of the mandrel (3) is adjusted separately as in Experimental Example (3).

<Effects of the Invention> As described above, according to the cooling device for resin molding of the present invention, the divided cooling body divided into at least two upper and lower parts is provided with mutually independent fluid paths, so that it is possible to supply fluid to each fluid path. By adjusting the temperature and flow rate of the fluid used, the cooling performance can be adjusted separately for the upper and lower parts, correcting the temperature difference between the upper and lower parts during the cooling process of the tubular sheet of thermoplastic resin extruded from the mold. Therefore, it is possible to obtain a foamed sheet (finished product) that is homogeneous on the top and bottom, and as a result, it has the unique effect of being able to obtain a homogeneous secondary product.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a cooling device for resin molding according to an embodiment of the present invention, FIG. 2 is an overall configuration diagram of a foamed resin molding machine, FIG. 3 is a perspective view, and FIG. 4 is a side view. (1)...Extruder, (2)...Mold, (3)...Mandrel, (31a) (31b) (32a) (32b) (
33a) (33b)...Divided cooling body, (71a)
(71b) (72a) (72b) (73a) (
73b) - = cooling pipe as a fluid path, (p)...tubular sheet Fig.

Claims (1)

[Claims] 1. A cooling device for resin molding that cools a tubular sheet of thermoplastic resin extruded horizontally from a mold by an extruder by contacting the inner or outer surface thereof, which is divided into at least two upper and lower parts. 1. A cooling device for resin molding, comprising divided cooling bodies, each of which is provided with a mutually independent cooling fluid path.