JP3330541B2 - Flat die for extrusion foam molding and extrusion molding method of foam sheet using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat die used for extruding and foaming a foamed sheet from a thermoplastic foamed resin material, and a method for extruding a foamed sheet using the same.

[0002]

2. Description of the Related Art As a method of extruding and foaming a foamed sheet from a thermoplastic foamed resin material, a method of extruding a plasticized resin from a flat die attached to a resin discharge port of an extruder is widely known. The conventional flat die shown in FIG. 7 has a movable lip (1) arranged side by side at the tip of a die body (10).
2) and a fixed lip (11), and a lip gap as a gap between the movable lip (12) and the fixed lip (11).
The size of (17) is set from the top of the die body (10) to the movable lip (1
The gap is adjusted by gap adjustment bolts (19) (19) screwed into 2). That is, the gap adjusting bolt (19) (1
9), the degree of screwing of the gap adjusting bolts (19) and (19) into the movable lip (12) changes,
(12) moves toward and away from the fixed lip (11), whereby the size of the lip gap (17), which is the gap between the movable lip (12) and the fixed lip (11), is adjusted.

[0003] This is an extruder shown by imaginary lines in FIG.
It is used by attaching it to the resin outlet of (3). The extruder
When the plasticized resin is discharged from (3), the lip gap (1
A sheet-like intermediate product (210) having a thickness corresponding to the size of (7) is continuously extruded from the lip gap (17). And
After cooling the sheet-like intermediate product (210) with a cooling device (not shown), the both side edges of the sheet-like intermediate product (210) are cut off with a slitter and the width thereof is aligned to obtain a long foamed sheet. This is taken up by the sheet take-up roll,
It is cut to the appropriate length and stacked.

In this apparatus, gap adjusting bolts (19) (1)
By changing the size of the lip gap (17) in 9), the thickness of the foamed sheet can be adjusted, and foamed sheets of various thicknesses can be obtained.

[0005]

However, when the conventional flat die is used to form a foamed sheet, especially a highly foamed sheet of twice or more, as shown in FIG. There is a problem that a wavy defective portion (23) is generated on both side edges of the extruded sheet-like intermediate product (210), and the width of the foamed sheet (21) obtained as a product is narrowed, thereby lowering productivity.

This is because when the sheet-like intermediate product (210) is extruded from the lip gap (17) while expanding in the width direction, the expansion is prevented at both ends of the lip gap (17). It is considered something. That is, sheet-shaped intermediate products
When each part in the width direction of (210) expands in the sheet width direction, the expansion of each part is cumulatively transmitted to both side edges of the sheet-like intermediate product (210). Attempts to extend significantly outward in the width direction. However, since the elongation is stopped at both ends of the lip gap (17), the large elongation is absorbed by the side edges of the sheet-like intermediate product (210) being deformed in a wavy shape, and the wavy shape as shown in FIG. It is considered that defective portions (23) and (23) occur.

The present invention has been made in view of the above points, and reduces the amount of wavy defective portions (23) formed on the side edges of a sheet-like intermediate product (210) extruded from a lip gap (17). Another object is to improve the productivity of the foamed sheet (21) by causing the sheet to disappear. [Invention of flat die for extrusion foam molding]

[0008]

Means for Solving the Problems The technical means of the present invention for solving the above-mentioned problem is that "a plastic foamed thermoplastic resin material is continuously discharged from a lip gap to form a long foamed sheet. A flat die for extrusion foam molding, wherein the lip gap is constituted by an end gap for extruding a side edge portion of the long foam sheet, and an inner gap other than the end gap. The gap dimension te corresponding to the thickness direction of the foam sheet at the end gap is sharply larger than that of the inner gap. "

According to the above technical means, as apparent from the test results described in the embodiments described later, the sheet-like intermediate product (2) continuously extruded from the lip gap (17).
The width of the wavy defective portion on the side edge of 10) can be reduced or eliminated. This is considered to be due to the following reasons.
According to the above technical means, the thickness of the plasticized resin extruded from the end gap is increased because the gap dimension of the end gap is sharply increased as compared with the internal gap. It becomes larger than the thickness. Therefore, thicker ears thicker than the other parts are continuously formed on the side edges of the sheet-like intermediate product (210) extruded from the flat die of the present invention in the extrusion direction. When the sheet-like intermediate product (210) is pushed out of the lip gap, the thick-walled ear portion functions as a reinforcing rib for suppressing wavy deformation of the sheet side edge. Further, the elongation in the width direction at the central portion of the sheet-like intermediate product (210) is absorbed as the cross-sectional expansion of the thick ear portion. It is considered that the waving deformation is suppressed by the reinforcing function or the expansion absorbing function.

As is clear from the above description, the term "exponentially increasing" described in the above technical means means that the side edge of the sheet-like intermediate product (210) has the above-mentioned reinforcing function or expansion absorption. It means the degree of change to such an extent that a rib-shaped thing that can be recognized as a thick-walled ear that exerts a function can be formed.

[0011]

The present invention has the following specific effects. Sheet-shaped intermediate product (210) extruded from the lip gap (17)
Since the generation amount of the wavy defective portion (23) formed on the side edge portion can be reduced or eliminated, the width of the foamed sheet (21) obtained as a product increases, and the production of the foamed sheet (21) increases. Performance can be improved.

* A In the above invention, the end gap may be formed only at one end of the inner gap, but the "end gap is formed separately at both ends of the inner gap." In such a case, the wavy deformation of both side edges of the foamed sheet (21) can be suppressed.

* B In the above invention, if the "end gap dimension te of the end gap can be adjusted independently of the gap dimension tc of the inner gap", various conditions such as resin material, resin temperature, etc. It is possible to freely adjust the size of the end gap having an optimum size that differs depending on the manufacturing conditions.

Item * c In the above item b, a specific configuration for adjusting the size of the end gap independently of the size of the inner gap is as follows: “The inner gap is the first lip member and the inner lip member. First
A gap between a second lip member facing a part of the lip member, wherein the end gap is formed between the first lip member and the first lip member;
A gap between the movable body that moves toward and away from the lip member on the side of the second lip member, and the movable body is fixed to an arbitrary position in the contact and separation operation area by fixing means.
By fixing the movable body to the predetermined position with the fixing means, the size of the end gap, which is the gap between the first lip member and the movable body, can be arbitrarily adjusted.

* D term In the above invention, the gap dimension te of the end gap may be set larger than that of the inner gap.
"The dimension We corresponding to the width direction of the foam sheet (21) in the end gap is 1 mm ≦ We ≦ 50 mm, and the gap dimension te corresponding to the thickness direction of the foam sheet (21) in the end gap. Is constant in the direction of the dimension We, the gap dimension tc corresponding to the thickness direction of the foamed sheet (21) in the inner gap is 2 mm or less, and the gap dimension te is tc <te ≦ 5 mm. It is possible to suppress the waving occurring at the side edge of the foamed sheet (21) with high accuracy.

If the inner gap has a variation in the gap size in the width direction of the foam sheet (21), the average size is the gap size tc. * E section The ratio of the gap dimension te to the gap dimension tc (te /
tc) can be set arbitrarily under the conditions described in the above section d. In the case of the above section d, “the gap size te of the end gap and the foam sheet (21) in the inner gap”
Of the gap dimension tc corresponding to the thickness direction (te / t
c) is set to 1 <te / tc ≦ 10 ”to form a foam sheet.
Extrusion molding of (21) is preferable from the viewpoint of harmonizing the above-mentioned reduction in the amount of occurrence of the wavy defective portion with the demand for preventing a decrease in productivity. When the ratio (te / tc) between the end gap and the inner gap is 1, the wavy deformation of both side edges of the foamed sheet (21) cannot be prevented as in the conventional case. This is because the thickness of the thick ears on both side edges of the intermediate product (210) becomes unnecessarily large, and the productivity is reduced.

* F. As described in item c, it is possible to adopt a configuration in which the gap dimension te corresponding to the thickness direction of the foam sheet (21) in the end gap is constant in the direction of the dimension We. As described above, it may be that "the gap dimension te corresponding to the thickness direction of the foam sheet (21) in the end gap increases as the distance from the inner gap increases". It was confirmed that the wavy defective portion at the side edge of the extruded sheet-like intermediate product could be reduced or eliminated.

* G section In the above-mentioned section f, the dimension We corresponding to the width direction of the foam sheet (21) in the end gap is 1 mm ≦ W
e ≦ 50 mm, and the difference between the gap dimension tec of the narrowest part and the gap dimension tee of the widest part in the end gap is 5 mm or less, and the thickness direction of the foam sheet (21) in the inner gap is And the average dimension (tec) corresponding to the thickness direction of the foamed sheet (21) in the end gap is 2 mm or less.
+ Te) / 2 is tc <((tec + tee) / 2)
≦ 5 mm ”. With such a configuration, it is possible to suppress, with high accuracy, a wavy defective portion generated at the side edge of the foamed sheet (21).

* H term average dimension (tec + tee) / 2 and the gap dimension t
The ratio of c (tec + tee) / 2tc can be arbitrarily set under the conditions described in the above item g, but in the case of the above item g, “the average size of the end gap (tec + tee) /
2 and the gap size tc of the inner gap ((t
ec + tee) / 2tc) is 1 <((tec + te + te)
e) / 2tc) ≦ 10 ”and extrusion-molding the foamed sheet (21), the same effects as those of the above-mentioned item e can be obtained. That is, it is possible to harmonize the reduction in the amount of the wavy defective portions on both side edges of the sheet-like intermediate product (210) with the demand for preventing the productivity from lowering.

[0020]

Next, an example of an embodiment of the present invention will be described. [First Embodiment] FIG. 1 is a schematic sectional view of an extrusion molding apparatus in which a flat die according to a first embodiment of the present invention appears, and FIG. 2 is a front view of the flat die. is there.

The extruder comprises an extruder (8) for plasticizing while kneading a thermoplastic resin and a foaming agent, and a breaker plate and a mesh for a resin discharge port (81) of the extruder (8). A flat die (1) connected through a filter (99) and an adapter (83)
A polishing unit (7) is provided as a cooling drawer for cooling and forming a sheet-like intermediate product (210) extruded from (1). Hereinafter, details of each unit will be described. <Structure of flat die> In the present embodiment, a coat hanger type flood die is adopted, and the die body
(10), a pair of upper and lower fixed lips (11) and a movable lip (12) disposed at the tip of the die body (10), and a die body (1
0) A choke bar (51) for adjusting the flow rate embedded in the cartridge, and a cartridge heater (61a) for adjusting the resin temperature.
(61b).

The present invention can be applied not only to the coat hanger die illustrated in this embodiment, but also to a fish tail die and a manifold die, and the flat die to which the present invention is applied has a flow path shape of the coat hanger die. The shape is not limited to the flow path shape. * About flat die (1) As shown in FIGS. 1 and 3, the coat hanger type flat die (1) used in the embodiment of the present invention has a plastic die flowing from the resin inlet (14) at the upstream end. A manifold section (13) having a large channel cross section for diffusing the activated resin throughout the width direction in the flat die (1) is formed, and the manifold section (13) has a flat surface as shown in FIG. The vision is bowed.

The above-mentioned manifold section (13) having a large flow path cross section
From the flat flow path (1
The opening 8) is adjusted by a choke bar 51 extending over the entire width of the die body 10. The choke bar (51) is loaded in a bar loading groove (53) whose lower end is open to the flat flow path portion (18) so as to be able to move up and down, and an adjusting screw screwed into the choke bar (51). It is designed to be raised and lowered at (55). In FIG. 1, a fixing screw (not shown) which is screwed in from the top surface of the die body (10) is provided in a portion located on the front and rear sides of the paper with respect to the adjusting screw (55). The choke bar (51) is pressed downward at the lower end of the fixing screw. Then, the choke bar (51) is fixed at a predetermined position by the fixing screw and the adjusting screw (55).

In the die body (10), cartridge heaters (61a) (61b) extending in parallel with the flat flow path portion (18) are provided.
Is embedded, so that the plasticized resin in the die body (10) can be maintained at a predetermined temperature. * Regarding the fixed lip (11) and the movable lip (12) At the tip of the die body (10), the first and second parts described above for adjusting the thickness of the plasticized resin discharged from the flat flow path part (18) are described. The fixed lip (11) and the movable lip (1
2) are arranged at intervals above and below.

As shown in FIG. 1 to FIG.
(11) is formed of a thick rectangular plate that is long in the width direction of the flat die (1), and the fixing lip (11) is fixed to the front surface of the die body (10) by fixing bolts (110) (110). It is fixed to. On the other hand, above the fixed lip (11), a movable lip (12) is provided in parallel, and these movable lip (12)
A lip gap (17) is formed between the lip gap and the fixed lip (11). A lip lifting bolt (122) (122) inserted from the top surface of the die body (10) is screwed into the movable lip (12), and the lip lifting bolt (122) (122) rotates. Accordingly, the movable lip (12) moves in the direction of coming and going with the fixed lip (11). Die body (10)
The top surface of the movable lip (12) is pressed by a lip pressing bolt (121) (121) screwed from the top surface of the lip, and the lip pressing bolt (121) and the lip lifting bolt (122) ), The movable lip (12) is fixed at a predetermined position.

As shown in FIGS. 1 and 2, the movable lip (12)
Are provided with long holes (98) (98) extending vertically.
(98) The fixing bolt (120) inserted from (98) is the die body
It is screwed into (10). Therefore, when the fixing bolt (120) is loosened, the slot (98) (98) is fixed to the fixing bolt (12).
0) The movable lip (12) can move up and down in a manner guided by (120).

In this case, the lip pressing bolt (12
After the upper and lower positions of the movable lip (12) are determined by 1) and the lip lifting bolt (122), when the fixing bolt (120) is tightened, the movable lip (12) is stabilized on the positioning portion. * About the movable bodies (71) and (72) The movable bodies (71) and (72) provided adjacent to both ends in the longitudinal direction of the movable lip (12) are L-shaped thick plates as shown in FIG. And the movable bodies (71) and (72) are
It is interposed between both ends of (12) and both side plates (77) and (78) of the die body (10) so as to be able to move up and down.

The movable members (71) and (72) are
11) It is moved in the direction of coming and going with the fixing lip (11) with (721), and the front fixing bolt (712) (72)
2) and side fixing bolts (713) (723) so as to be fixed at predetermined positions. For this reason, the die body (1
On both side plates (77) and (78) of (0), elongated holes (67) and (68) extending in the moving direction of the movable bodies (71) and (72) are formed, and the elongated holes (6
7) The distal ends of the side fixing bolts (713) and (723) inserted from (68) are screwed into the movable bodies (71) and (72). Also, the movable body
Slots (95) and (96) extending in the moving direction of the movable bodies (71) and (72) penetrate through (71) and (72), and are inserted through the slots (95) and (97). The tip of the front fixing bolt (712) (722) is
0).

In this case, the lifting bolt (711)
After moving the movable body (71) (72) up and down with (721), tighten the front fixing bolts (712) (722) and the side fixing bolts (713) (723), and the movable bodies (71) (72) Fixed in position. As a result, the size of the end gaps (17a) (17b) between the fixed lip (11) and the movable bodies (71) (72) can be adjusted. The end gap (17a) (17) corresponding to the width direction of the foam sheet (21)
The dimension We of b) is constant.

In the flat die of the present invention,
The entire length of the lip gap (17) including the end gaps (17a) and (17b) and the inner gap (17c) (the length in the width direction of the foam sheet (21)) is not particularly limited. Foam sheet (2
This is because the wavy defective portion generated on both side edges of 1) is generated with a substantially constant width from both side edges of the foamed sheet (21) regardless of the sum of the lengths of the end gap and the inner gap. Therefore, even if the width of the foam sheet (21) to be manufactured becomes large, the cut width of both side edges which must be cut does not increase, and the highly productive foam sheet (21) can be manufactured. <Structure of Extruder (8)> The type of extruder to which the flat die is attached is not particularly limited, but a single screw extruder is employed in the present embodiment.

The single-screw extruder is the most common extruder, and is widely used because the foaming gas rarely comes out of the hopper and is inexpensive. As shown in FIG. 1, heaters (86) (86) for temperature adjustment are wound around the outer periphery of a cylindrical barrel (85) constituting the extruder (8). still,
A not-shown cooling device (cooling water supply device or air fan) for temperature adjustment is also provided. A screw (88) is loaded inside the barrel (85), and the barrel (8)
On the upper surface of 5), a hopper (89) for supplying a thermoplastic resin material is provided continuously near the upstream end of the screw (88). Further, a driving device (82) for rotating the screw (88) is provided at the rear end of the barrel (85).

In the present embodiment, a single-screw extruder is employed as described above, but a multi-screw extruder represented by a twin-screw extruder can also be used. As the twin-screw extruder, there are those in which the rotation directions of the screws are the same and those in the opposite direction, and there are a parallel twin-screw with a constant screw diameter and an inclined twin-screw with a small screw tip diameter. In the case of a twin-screw extruder, it is preferable to provide a sealing segment on the screw, since the foaming gas easily escapes from the hopper.

Also, a tandem extruder in which the above extruders are connected and combined can be used. <Structure of Polishing Unit (7), etc.> As shown in FIG.
A vertical three-roll type with three rotating rolls (70a), (70b) and (70c) arranged side by side is used.
The sheet-like intermediate product (210) extruded from (1) passes between the rotating rolls (70a) (70b), and then passes through the rotating roll (70b).
And a slitter (not shown) which cuts both edge portions of the sheet-like intermediate product (210) in a direction in which the sheet flows in a slitter (not shown) through the space between the rotating roll (70c) and the upper portion thereof. The sheet (21) is wound on a product winding roll. When a foamed sheet (21) having a thickness large enough to be difficult to wind up on a product take-up roll is formed, the sheet-like intermediate product (210) is cut into appropriate lengths and stacked. <Use Materials> The thermoplastic resin material used in the present invention is not particularly limited, and can be selected according to the use of the product. Generally, polyethylene-based resin, polypropylene-based resin, polystyrene-based resin, polyvinyl chloride-based resin and the like are used, and a blend of these can be used. <About the blowing agent> The blowing agent is not particularly limited, and a carbon dioxide gas, a nitrogen gas, a physical blowing agent such as butane, baking soda, and a chemical blowing agent such as azodicarboxylic acid amide can be used. It is possible. Further, an inorganic filler such as talc or silica may be added as a foam nucleating agent. <Practical Extrusion Foam Molding> Next, the actual extruded foam molding using the above-described extrusion molding apparatus will be described.

First, the position of the movable lip (12) is adjusted.
Fixing bolt (120) (120) and lip pressing bolt (121) (12
1) Loosen the lip lifting bolt (122) (122)
Is rotated, the screw-in amount of the lip lifting bolts (122) (122) with respect to the movable lip (12) changes,
Inner gap between movable lip (12) and fixed lip (11)
The size of (17c) is adjusted. Then, in this adjusted state, the lip pressing bolt (121) (121) and the fixing bolt (120) (12
When 0) is tightened, the movable lip (12) is fixed in the adjustment position as described above.

Next, the positions of the movable bodies (17) and (17) are adjusted.
Front fixing bolt (712) (722) and side fixing bolt (713)
When the lifting bolt (711) (721) is rotated with the (723) loosened, the end gaps (17a) (17b) between the fixed lip (11) and the movable bodies (71) (72) are adjusted. You. By adjusting the end gaps (17a) and (17b) in this manner, the end gaps (17a) and (17b) are set to be larger than the inner gap (17c).

Next, when the pellet-shaped thermoplastic resin material and the foaming agent are put into the hopper (89) and the driving device (82) is driven, the foaming agent and the thermoplastic resin material are heated by the heater (86). It is melted and kneaded by the shearing force of the screw (88), and the plasticized resin as the kneaded material is fed from the adapter (83) to the flat die.
The fluid is supplied to the flat flow path section (18) through the manifold section (13) of (1). Then, the sheet-like intermediate product (210) is discharged from the lip gap (17) adjusted by the fixed lip (11) and the movable lip (12) located adjacent to the downstream end of the flat channel portion (18). You. That is, as shown in FIG. 4, the central portion (218) pushed out from the inner gap (17c) and the end gaps (1
7a) A sheet-shaped intermediate product (210) having thick-walled ears (219) and (219) extruded from (17b) is discharged from the lip gap (17), and this is a rotating roll constituting the polishing unit (7). (70a) (70b) It is taken off while being cooled in (70c). Thereafter, the thick-walled ears (219) (219) on both sides of the cooled sheet-shaped intermediate product (210) are slit by a slitter (not shown) to form a foamed sheet (21), and the foamed sheet (21) is formed. 21) is wound on a product take-up roll (not shown) or cut and loaded.

The foamed sheet (21) to be produced according to the present invention
Has a foaming ratio of 2 to 50 times, and the foamed sheet (21) has a thickness of 1 mm to 100 mm. The expansion ratio is generally determined by the amount of the foaming agent described above,
The thickness of the foam sheet (21) depends on the expansion ratio, the lip gap
(17), resin swell characteristics, resin temperature, shear rate,
It is determined by processing conditions such as the take-up speed of the polishing unit (7).

The size of the inner gap (17c) of the flat die is generally determined by the use of the product in the above range, but the size of the inner gap (17c) (the gap size tc corresponding to the thickness direction of the foamed sheet (21)). ) Is based on the premise that extrusion molding is performed in a state of being set to 2 mm or less. Since the size of the inner gap (17c) generally has a slight variation depending on the location, strictly speaking, the gap size tc means the average size of the inner gap (17c). I do. The gap dimension te of the end gaps (17a) (17b) corresponding to the thickness direction of the foam sheet (21) is 5 mm or less. <Manufacturing Test> Next, a description will be given of a test result obtained by measuring the dimensions and the like of each part of the foamed sheet (21) manufactured using the flat die according to the above embodiment.

The dimensions and molding conditions of each part of the flat die used in each of the following tests and comparative examples are shown in a list in FIG. * Test 1 For an extruder, barrel diameter D (see FIG. 1) = 120 mm
Φ, effective screw length L / D = 36 (where L is the dimension from the hopper (89) to the tip of the screw (88))
Using a single-screw extruder with a die width of 1
A 500 mm one equipped with a choke bar (51) was used. Further, using a flat die in which the dimension We corresponding to the width direction of the foam sheet (21) in the end gaps (17a) and (17b) is set to 20 mm, along the width direction of the foam sheet (21) The gap size te, which is the size of the end gaps (17a) and (17b), is fixed and the size is set to 1.5 mm, and the foam sheet (21) in the inner gap (17c) is set.
The test was conducted by setting the ratio (te / tc) to 3.0, with the gap dimension tc corresponding to the thickness direction of 0.5 mm being 0.5 mm.

As the thermoplastic resin, polypropylene (MFR (melt flow rate, 230 ° C.) = 6) was used, and 3.5 parts by weight of a polypropylene-based master batch containing 30 wt% of baking soda as a blowing agent was used. The mixture was added and blended in a pellet state by a tumbler, and then charged into a hopper (89). The operating conditions of the extruder were as follows: the screw rotation speed was 40 rpm, and the resin discharge amount was 20.
0 kg / hr, the temperature of the supply section (31) (see FIG. 1) near the upstream end of the screw was set to 170 ° C. to 200 ° C. by the heaters (86) and (86).
℃, the temperature of the compression section (32) following the supply section (31) is 190
The material is sufficiently melt-kneaded at a setting of 00 ° C. to produce a plasticized resin, and the plasticized resin (the foaming gas in which the foaming agent is decomposed is uniformly dissolved) is heated at 160 ° C. ~ 1
The plasticized resin was uniformly cooled to a temperature suitable for foaming while maintaining the temperature at 70 ° C., and the plasticized resin was passed through an adapter (83) into a flat die (1) whose temperature was adjusted to 170 ° C. to 180 ° C. by a cartridge heater (41). ). In addition, as a cooling take-off machine,
The axial length is 1600 mm and the diameter is 40
A polishing unit (7) having a roll of 0 mmφ was used in which the temperature was adjusted to 60 ° C to 100 ° C.

As a result, no wavy defective portion is generated on both side edges of the sheet-like intermediate product (210) extruded from the flat die, and the effective width (width that can be effectively used as a sheet) close to the die width is 1450 mm. Good appearance foam sheet (2
1) was obtained. The expansion ratio was 3 times, and the average value of the wall thickness was 3 mm. As Comparative Example 1 with respect to the above Test 1, except that the size of the end gap was made constant along the width direction of the foamed sheet (21) and the gap dimension te was set to 0.5 mm which is the same as the gap dimension tc of the inner gap. Molding was performed under the same conditions as in Test 1.

As a result, wavy defective portions are generated on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1), and the total width of the defective portions on both side edges is 20%.
The effective width is 130 mm because the material loss is large at 0 mm.
It became as narrow as 0 mm. The expansion ratio was 3 times, and the average value of the wall thickness was 3 mm. * Test 2 Using a flat die (1) in which the above dimensions We of the end gaps (17a) and (17b) are set to 10 mm, use a foam sheet.
The size of the end gaps (17a) and (17b) is constant along the width direction of (21), the gap dimension te is set to 2.0 mm, and the gap dimension tc of the inner gap (17c) is set to 0.5 m.
As m, these ratios (te / tc) were set to 4.0, and the other conditions were set similarly to the above Test 1.

As a result, there is no wavy defective portion on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1), and a foam sheet having an effective width close to the die width of 1470 mm and having a good appearance. (21) was obtained. The expansion ratio is 3
The average value of the wall thickness was 3 mm. * Test 3 The size of the end gaps (17a) (17b) along the width direction of the foam sheet (21) using a flat die in which the above-mentioned dimension We of the end gaps (17a) and (17b) is set to 2 mm. And the gap dimension te is set to 3.5 mm,
The gap size tc of the inner gap (17c) was set to 0.5 mm, the ratio (te / tc) was set to 7.0, and the other conditions were set the same as in Test 1 described above.

As a result, there is no wavy defective portion on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1), and a foam sheet having an effective width close to the die width of 1480 mm and having a good appearance. (21) was obtained. The expansion ratio is 3
The average value of the wall thickness was 3 mm. * Test 4 The size of the end gaps (17a) (17b) along the width direction of the foam sheet (21) using a flat die in which the above-mentioned dimension We of the end gaps (17a) and (17b) is set to 2 mm. And the gap dimension te is set to 2.0 mm,
The gap size tc of the inner gap (17c) was set to 0.5 mm, the ratio (te / tc) was set to 4.0, and the other conditions were set the same as in Test 1 described above.

As a result, wavy defective portions are generated on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1), and the total width of the defective portions on the both side edges is 90%.
mm, but the effective width close to the die width was 1410 mm
A foam sheet (21) having a good appearance was obtained. The expansion ratio was 3 times, and the average value of the wall thickness was 3 mm. * Test 5 Using a flat die (1) in which the above dimensions We of the end gaps (17a) and (17b) are set to 2 mm,
The size of the end gaps (17a) and (17b) is constant along the width direction of (1), the gap dimension te is set to 1.5 mm, and the gap dimension tc of the inner gap (17c) is set to 0.5 mm.
And set these ratios (te / tc) to 3.0,
Otherwise, the same conditions as in Test 1 were set.

As a result, wavy defective portions are formed on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1), and the total width of the defective portions on the both side edges is 10%.
0mm, but the effective width close to the die width is 1400m
m, a foamed sheet (21) having a good appearance was obtained. The expansion ratio was 3 times, and the average value of the wall thickness was 3 mm. * Test 6 The amount of the foaming agent masterbatch was increased to 10 parts by weight,
Using a flat die in which the above-mentioned dimensions We of the end gaps (17a) and (17b) are set to 20 mm, use a foam sheet (21).
The size of the end gaps (17a) and (17b) is made constant along the width direction of the above, the gap dimension te is set to 4.0 mm, and the gap dimension tc of the inner gap (17c) is set to 1.0 mm.
And set these ratios (te / tc) to 4.0,
Otherwise, the same conditions as in Test 1 were set.

As a result, there is no wavy defective portion on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1), and a foam sheet having an effective width close to the die width of 1450 mm and having a good appearance. (21) was obtained. The expansion ratio is 6
The average value of the wall thickness was 13 mm. As Comparative Example 2 for the above Test 6, the size of the end gaps (17a) and (17b) was made constant along the width direction of the foam sheet (21), and the gap size te was set to the gap size tc of the inner gap (17c). The molding was performed under the same conditions as in Test 6 except that the distance was set to 1.0 mm.

As a result, a wavy defective portion is generated on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1), and the total width of the defective portion on both side edges is 20%.
The effective width is 130 mm because the material loss is large at 0 mm.
It became as narrow as 0 mm. The expansion ratio was 6 times, and the average value of the wall thickness was 13 mm. * Test 7 Low-density polyethylene (190
° C, MFR = 2), the feeding part (31), the compression part (32),
Molding was performed under the same conditions as in Test 2, except that the temperature of the measuring section (34) and the die body (10) were lowered by 20 ° C.

As a result, the foamed sheet (21) extruded from the flat die does not have any wavy defective portions on both side edges, and the foamed sheet (21) having an effective width close to the die width and having a good external appearance of 1470 mm is obtained. Was done. The expansion ratio was 3 times, and the average value of the wall thickness was 3 mm. As Comparative Example 3 for the above Test 7, the size of the end gaps (17a) and (17b) was made constant along the width direction of the foamed sheet (21), and the gap size te was set to the gap size tc of the inner gap (17c). Molding was carried out under the same conditions as in Test 7 except that the distance was set to 0.5 mm.

As a result, wavy defective portions are formed on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1), and the total width of the defective portions on both side edges is 25%.
0 mm, a large amount of material loss occurs, and the effective width is 125.
It became as narrow as 0 mm. The expansion ratio was 3 times, and the average value of the wall thickness was 3 mm. [Second Embodiment] As shown in FIG. 5, in the second embodiment, a movable member (71) (72) for adjusting the size of the end gaps (17a) (17b) is provided. The configuration is the same as that of the first embodiment described above, except that the tip on the fixed lip (11) side is inclined.

The tips of the movable bodies (71) and (72) on the fixed lip (11) side are fixed to the fixed lip (1) as they approach the side plates (77) and (78).
It is inclined linearly to deviate from 1). still,
End gap (17a) corresponding to the thickness direction of the foam sheet (21)
The average dimension tea of (17b) is set to 5 mm or less. <Production test> Next, the foam sheet (21) produced using the flat die according to the second embodiment is described.
The test results obtained by measuring the dimensions and the like of each part will be described.

* Test 8 Along the width direction of the foamed sheet (21), the end gap (17a) (17
The size of b) (corresponding to the thickness of the foam sheet (21)) varies linearly, and a flat die in which the above-mentioned dimension We of the end gaps (17a) and (17b) is set to 20 mm was used. Further, the gap size te of the widest portion of the outer end of the end gaps (17a) and (17b) is set to 3.5 mm, and the gap size tec of the opposite narrowest portion is set to 0.5 mm. Ratio (tee / tec) is 3.5
/0.5. Therefore, in this case, tea =
((Tee + tec) / 2) is set to 2 mm. Also, the gap size tc of the inner gap (17c) is set to 0.5
mm, and tea / tc was set to 4.0. Otherwise, the same conditions as in Test 1 were set.

As a result, there is no wavy defective portion on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1), and a foam sheet having an effective width close to the die width of 1470 mm and having a good appearance. (21) was obtained. The expansion ratio is 3
The average value of the wall thickness was 3 mm. * Test 9 The amount of the foaming agent masterbatch was increased to 10 parts by weight,
Otherwise, the same conditions were set as in Test 8 above.

As a result, the sheet-like intermediate product (210) extruded from the flat die does not have any wavy defective portions on both side edges, and has a good appearance with an effective width close to the die width of 1450 mm (21). was gotten. The expansion ratio was 6 times, and the average thickness was 6 mm. As Comparative Example 4 to the above Test 9, except that the size of the end gaps (17a) and (17b) was constant along the width direction of the foamed sheet (21) and the gap dimension te was set to 0.5 mm, 9
Molded under the same conditions as

As a result, wavy defective portions are generated on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1), and the total width of the defective portions on both side edges is 30%.
0 mm, a lot of material loss occurs and the effective width is 120
It became as narrow as 0 mm. The expansion ratio was 6 times, and the average thickness was 6 mm. [Others] In the above tests, flat dies having end gaps (17a) and (17b) in the range of 2 mm ≦ We ≦ 20 mm were used. However, in the flat dies of the first and second embodiments, We = Even when set to 1 mm, the sheet-like intermediate product (21
The width of the wavy defective portion on both side edges of (0) becomes smaller.

It is easy to infer that when 20 mm <We is set, the width of the wavy defective portion is further reduced. In the flat dies of the first and second embodiments, the gap dimension tc of the inner gap (17c) is 0.5 m.
Even if the width is less than m, the width of the wavy defective portion becomes small. In the first embodiment, as long as the gap dimension te of the end gaps (17a) and (17b) corresponding to the thickness direction of the foam sheet (21) is larger than the gap dimension tc of the inner gap (17c), both are equal. The width of the wavy defective portion can be made smaller than that of the case. This is because thick-walled ears (219) functioning as reinforcing ribs for preventing waving are formed on both side edges of the sheet-like intermediate product (210) extruded from the flat die (1). In the second embodiment, the end gap (17a) (17
As long as the average dimension (tec + tee) / 2 corresponding to the thickness direction of the foamed sheet (21) in (b) is larger than the gap dimension tc of the inner gap (17c), it was confirmed that the wavy defective portion was reduced.

[Brief description of the drawings]

FIG. 1 shows a flat die (1) according to an embodiment of the present invention.
Schematic cross-sectional view of extrusion molding equipment with

FIG. 2 is a flat die according to an embodiment of the present invention (1).
Front view of partly cut away

FIG. 3 is a flat die (1) according to an embodiment of the present invention.
Cross section of

FIG. 4 is an end view of a partly omitted sheet-like intermediate product (210).

FIG. 5 is a flat die according to a second embodiment.
Front view of partly cutout of (1)

FIG. 6 is a table showing test results.

FIG. 7 is an explanatory view of a conventional example.

[Explanation of symbols]

 (1) ... flat die (8) ... extruder (11) ... fixed lip (12) ... movable lip (17a) (17b) ... end gap (17c) ... inside Gap (21): Foam sheet (51): Choke bar (210): Sheet-shaped intermediate product

Continuation of the front page (56) References JP-A-60-67129 (JP, A) JP-A-2-19523 (JP, U) JP-A-59-104709 (JP, U) JP-B-38-11823 (JP) , B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 47/00-47/96

Claims (9)

(57) [Claims] 1. A flat die for extrusion foam molding for forming a long foam sheet by continuously discharging a plasticized thermoplastic foam resin material from a lip gap, wherein the lip gap is An end gap for extruding the side edge portion of the elongated foam sheet and an inner gap other than the end gap, and a gap dimension te corresponding to the thickness direction of the foam sheet at the end gap
Is a flat die for extrusion foaming, which is sharply larger than that of the inner gap. 2. The flat die for extrusion foam molding according to claim 1, wherein said end gaps are formed separately at both ends of said inner gap. 3. The gap dimension te of the end gap
The flat die for extrusion foam molding according to claim 1 or 2, wherein the flat die is adjustable independently of a gap dimension tc of the inner gap. 4. The inner gap is a gap between a first lip member and a second lip member facing a part of the first lip member, and the end gap is formed between the first lip member and the first lip member. The extrusion according to claim 3, wherein the gap is a gap between a movable body that moves toward and away from the lip member on the side of the second lip member, and the movable body is fixed to an arbitrary position in the contact and separation operation area by a fixing unit. Flat dies for foam molding. 5. Foam sheet (21) in said end gap
The dimension We corresponding to the width direction is 1 mm ≦ We ≦ 50 mm
The gap dimension te corresponding to the thickness direction of the foam sheet (21) in the end gap is constant in the direction of the dimension We, and the thickness of the foam sheet (21) in the inner gap is The flat die for extrusion foam molding according to any one of claims 1 to 4, wherein a gap dimension tc corresponding to the direction is 2 mm or less, and the gap dimension te is in a range of tc <te ≤ 5 mm. 6. A method for extruding a foamed sheet using a flat die for extrusion foaming according to any one of claims 1 to 5, wherein a gap dimension te of the end gap is provided.
And the ratio (te / tc) of the gap dimension tc corresponding to the thickness direction of the foamed sheet (21) in the inner gap to 1 <
A method for extruding a foamed sheet, wherein te / tc ≦ 10 is set to form a foamed sheet. 7. The foam sheet at the end gap
The flat die for extrusion foam molding according to any one of claims 1 to 4, wherein the gap dimension te corresponding to the thickness direction of (21) increases as the distance from the inner gap increases. 8. Foam sheet (21) in said end gap
The dimension We corresponding to the width direction is 1 mm ≦ We ≦ 50 mm
And a gap dimension t of the narrowest part in the end gap.
ec and the gap size tee of the widest part is 5
mm or less, a gap size tc corresponding to the thickness direction of the foam sheet (21) in the inner gap is 2 mm or less, and an average size corresponding to the thickness direction of the foam sheet (21) in the end gap. (Tec + tee) / 2 is tc <
8. The flat die for extrusion foam molding according to claim 7, wherein ((tec + tee) / 2) ≦ 5 mm. 9. A method for extruding a foamed sheet using a flat die for extrusion foaming according to claim 7 or 8, wherein the average size of the end gap (tec + tee).
/ 2 and the gap dimension tc of the inner gap ((tec + tee) / 2tc) is 1 <((tec +
tee) / 2tc) An extrusion molding method of a foamed sheet in which a foamed sheet is formed by setting ≦ 10.