JPH07205254A - Die for manufacturing sheet material and method for manufacturing sheet material - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Even when melt extruding for a long time, the effect of rattling and creep does not occur on the individual heat bolts 3A to 11A, and the thermal expansion amounts of the heat bolts are the same. A die that can be more clearly secured to a heat bolt is provided, and the extrusion thickness in the width direction of the sheet-like material is easily made constant. In a die for producing a sheet-like material in which a synthetic resin is continuously extruded from a slit gap of a pair of opposed lip blocks 23, 24, a plurality of heat bolts 3A are provided on one lip block 23 in the longitudinal direction of the slit gap. ~ 11
A is arranged, and each of them is provided with a heating means 16 connected to a control device 17 to which a temperature program for eliminating the thickness unevenness of the sheet-like material 21 is input. On the other hand, the other lip block 24 is provided with a plurality of manual adjustment bolts 3B to 11B in the longitudinal direction of the slit gap 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in a die for producing a sheet material such as a thermoplastic synthetic resin film and a method for producing the sheet material. The present invention relates to a die that can be kept constant and a method for manufacturing the sheet-like article.

[0002]

2. Description of the Related Art In recent years, the thickness accuracy required for a biaxially stretched film has become increasingly severe. Here, if the slit gaps of the die are made uniform, it is not possible to obtain a biaxially stretched film having a uniform thickness that meets the above requirements. Because, in order to make the thickness of the biaxially stretched film uniform, as is well known, it is necessary to form the slit gap in the width direction of the die in a certain pattern. Generally, when the die type is a T-die, this pattern is a pattern in which the slit gap at the center of the die is narrow and the slit gap at both ends is wide. The thickness of the biaxially stretched film is made uniform by facilitating the flow of the thermoplastic synthetic resin, which tends to lean, to both ends of the die. Conventionally, as a method for adjusting the thickness of such a thermoplastic synthetic resin film, as is known in US Pat. No. 3,940,221, a heat bolt method that utilizes expansion and contraction by heating and cooling of bolts is generally used. That is,
In this method, in the die having a fixed lip and a movable lip provided with the plurality of heat bolts, the die discharge part applies energy to the heating means of the die corresponding to the position according to the thickness information of the film. By increasing or decreasing the heat bolt, the heat bolt is heated and cooled, and the tip of the lip expands and contracts to adjust the slit gap constant.

As a material for the heat bolt, the one disclosed in Japanese Utility Model Laid-Open No. Sho 60-78420 is known, which is a material for only a specific heat bolt which requires slit clearance adjustment. Which have been commonly used from, for example, carbon steel for machine structure (JIS G4051-19
79-8) 18-8 stainless steel (JIS G4303-1981), which has a larger linear expansion coefficient than ordinary steel.

[0004]

However, in the die using only the above-mentioned conventional heat bolt method, the lip deformation amount is limited because the thermal expansion of the bolt material is utilized, and at most 200 to at most. It is up to about 300 μm. However, in order to obtain a biaxially stretched film having a uniform thickness as described above, a particularly thick film is
When forming a film with a die, it is necessary to deform the slit gap between the center and both ends of the die by 400 μm or more. For this reason, generally, as also employed in the die of US Pat. No. 3,940,221, the head of the heat bolt is threaded so that the slit gap can be adjusted manually. However, the method that uses both a heat bolt that is automatically adjusted by thermal expansion and contraction and a manual bolt that is manually adjusted by one heat bolt in this way has a so-called rattling between the male and female screws. The thermal expansion of is absorbed by the backlash and the movable lip does not move. There is an example in which a spring is forcibly absorbed to eliminate this play, but the heating temperature of the heat bolt is 500
Since it may reach over ℃, the elasticity of the spring is lost and the problem of backlash of the screw occurs again.

Further, the above heat bolt materials include
There were the following problems.

The heat bolt made of 18-8 stainless steel has a linear expansion coefficient larger than that of ordinary steel, and thus has an advantage that a wide range of slit gaps can be obtained, but the tensile strength at high temperature is ordinary steel. However, the tensile strength at 20 ° C. is low because the former is 60 kg / mm ² and the latter is 80 kg / mm ² .

Therefore, when continuously used at a high temperature for a long time, the amount of thermal expansion increases, but the reaction force from the movable lip also increases, which causes a larger internal stress, and the mechanical strength is increased each time the heating is repeated thereafter. A so-called creep phenomenon occurs, which lowers the thermal expansion amount of the heat bolt, and eventually the thickness of the product becomes uneven.

In this case, in order to make up for the insufficient tensile strength of 18-8 stainless steel, the rigidity of the lip portion may be designed to be low, but in this case, the pressure change of the molten resin inside the die immediately propagates to the slit gap. There is a risk that new thickness unevenness may occur, so there is naturally a limit to the design for reducing the rigidity of the lip portion.

In addition, in order to make up for the lack of tensile strength, 18-8 stainless steel is used only in the portion of the heat bolt where the heat expands, and chromium molybdenum steel having high tensile strength is used in the other portions. The generated heat energy spreads to the adjacent heat bolts, and it was impossible to set the differentiated temperature between the heat bolts in the die width direction.

The present invention has been made in view of the above conventional problems, and the object of the present invention is to: Even when a sheet-like product is produced over a long period of time, each heat bolt is not affected by backlash caused by a screw or creep, and the amount of thermal expansion can be easily controlled. The present invention provides a practical die for producing a sheet-like material in which the thermal expansion amount of the heat bolt can be more clearly ensured with respect to the adjacent heat bolt, and It is an object of the present invention to provide a method for producing a sheet-shaped product, which can make the extruded thickness of the sheet-shaped product constant in the width direction.

[0011]

In order to achieve the above object, a sheet-shaped article manufacturing die according to the present invention is provided with a thermoplastic synthetic resin from the slit gaps of a pair of lip blocks facing each other with a slit gap. A die for producing a sheet material for continuously extruding a sheet material,
(A) In one lip block, a plurality of heat bolts are arranged in the longitudinal direction of the slit gap, and (b) in each of the heat bolts, the uneven thickness of the sheet is eliminated. A heating means connected to a control device to which a temperature program for inputting the temperature program is input, and (c) the other lip block is provided with a plurality of manual adjustment bolts in the longitudinal direction of the slit gap. It is characterized by In this case, the heat bolt has a thermal conductivity of 5 to 25 kc at 20 ° C to 700 ° C.
It is made of an alloy steel having a physical property of al / m · hr · ° C and a tensile strength in the temperature range of 70 to 150 kg / mm ² , and the alloy steel has a composition of 70% by weight or more of Ni.
Is preferred. Further, it is more preferable that the heating means of the heat bolt is a cartridge heater built in the vicinity of the one lip block of the bolt.

The method for producing a sheet-like article according to the present invention is a sheet-like article for producing a sheet-like article by continuously extruding a thermoplastic synthetic resin from the slit gaps of a pair of lip blocks facing each other with a slit gap. (A) A heat bolt having a heating means built in one of the lip blocks of the pair of lip blocks, and a manual adjustment bolt for the other lip block are both provided in the longitudinal direction of the slit gap. (B) If a large slit gap is required at least when the extrusion of the thermoplastic synthetic resin is disclosed, the slit gap is adjusted with the manual adjustment bolt, and (c) the heat When a small slit gap adjustment is required during extrusion of the plastic synthetic resin, the heating means for each of the plurality of heat bolts is used to adjust the thickness of the sheet-like material. Characterized by automatically controlling individually by a control device temperature program is entered for eliminating al. In this case, the heat bolt has a thermal conductivity of 5 to 25 kcal at 20 to 700 ° C.
/ m · hr · ° C and a tensile strength in the temperature range of 70 to 150 kg / mm ² of an alloy steel having physical properties, and the alloy steel further comprises 70% by weight or more of the composition of Ni. It is preferable to use one.

By the way, in the present invention, the heat bolt means a plurality of bolts provided at a predetermined interval in the width direction of the slit gap of one lip block for the purpose of adjusting the slit gap of the die for manufacturing a sheet material. hand,
The lip block is elastically deformed to obtain a desired slit gap. Further, the heating means means a heating device which causes the heat bolts to be thermally expanded in the axial direction by individually heating the heat bolts, and examples thereof include a cartridge heater and a heat pipe. This heating device is preferably incorporated in the heat bolt because heat energy can be converted into thermal expansion without waste and there is no adverse effect due to heat radiation to the adjacent heat bolt.

Here, when the mechanism of thermal expansion is analyzed in order to obtain a large amount of thermal expansion, the amount of thermal expansion ΔL is expressed by the following equation. ΔL = α · L · Δt where α: linear expansion coefficient L: length of thermal expansion portion of heat bolt shaft Δt: temperature difference due to heating device The means for expanding the thermal expansion amount ΔL from the above equation is first It is conceivable to use a material having a large linear expansion coefficient α in No. 1 as the heat bolt. However, as shown in the above-mentioned Japanese Utility Model Application Laid-Open No. 60-78420, focusing on only the material having a large linear expansion coefficient α, the mechanical strength In particular, if the material is selected while ignoring the tensile strength, which is a typical strength of metal, permanent distortion due to the creep phenomenon occurs, and there is a problem that it cannot be practically used.

As a second means, it is conceivable to lengthen the length L of the shaft portion of the heat bolt, but as a practical matter, space restrictions are involved and the die as a whole becomes heavy, which is not an appropriate means. Therefore, as a result of intensive investigations by the present inventors in order to secure the maximum temperature difference Δt by the heating device, which is the last means, as a result, heat conduction to the material of the heat bolt does not depend on the large linear expansion coefficient α. Focusing on the fact that the slit gap between the heat bolt and the adjacent heat bolt can be efficiently differentiated and expanded by using a material with a low rate, and at the same time, the creep phenomenon, which is the problem of the conventional die, can be eliminated at the same time. Found. According to the experiments by the inventors,
It has been found that the heat conductivity of the heat bolt at a practical temperature of 20 ° C to 700 ° C is preferably in the range of 5 to 25 kcal / m · hr · ° C, more preferably 12 to 20 kcal / m · hr · ° C. . If the thermal conductivity exceeds 25 kcal / m · hr · ° C, the temperature difference between the die body and the adjacent heat bolt cannot be obtained due to heat radiation, and the desired slit gap in the die width direction cannot be obtained. In addition, the lower limit of thermal conductivity is 5
The numerical value of kcal / m · hr · ° C is the lower limit value of a practical metal that satisfies both the thermal conductivity and the tensile strength of the present invention at the same time, and it is needless to say that the lower the numerical value, the better. Yes. If the thermal conductivity is low, it may take a long time until the desired slit gap is obtained, but it is about 10 minutes, which is not a problematic level in actual film formation. Next, the preferable value of the tensile strength is 70 to 150 kg / mm ² at the above-mentioned practical temperature, and more preferably 80 to 110 kg / mm ² . Tensile strength is 70kg
If it is less than / mm ² , the creep phenomenon becomes remarkable, the heat bolt cannot fully oppose the reaction force from the movable lip, and the desired slit gap cannot be obtained in the die width direction. In addition, the upper limit of tensile strength of 150 kg / mm ² is also the upper limit of practical metals that can exist at present similarly to the thermal conductivity, and it goes without saying that the higher the value, the better. Any metal having such thermal conductivity and tensile strength may be used, but as a practical metal, there is, for example, a corrosion-resistant heat-resistant superalloy steel (JIS G4901-1981, see Table 1) or the like, and the composition of the metal. Indicates that Ni is contained in 70% or more by weight. If the total composition of Ni and Cr is less than 50%, the tensile strength becomes extremely insufficient, and the creep phenomenon cannot be endured. The methods for measuring the physical properties such as the thermal conductivity, the tensile strength, and the total composition of Ni and Cr are the flat plate comparison methods (JIS A1412-
1977) or the direct plate method (JIS A1413-1)
977), metal material tensile test method (JIS G0567-
1978 or JIS Z2241-1980) and ladle analysis method (JIS G0303-1972).

In the present invention, the manual adjusting bolt is a slit gap adjusting bolt provided on the fixed lip, and the operator manually pushes and pulls the bolt to adjust the slit gap in the width direction. Is a constant adjustment. Specific examples include differential screws and trapezoidal screws. That is, the sheet-shaped article manufacturing die of the present invention is, as the slit gap adjusting means, each of the pair of lip blocks formed through the slit gap, an automatic adjustment bolt consisting of a manual adjustment bolt and the heat bolt of the specific material. Two adjusting means for adjusting bolts are provided.

[0017]

The present invention has the above-mentioned structure and has the following unique operation. ◎ 1) First, by separating the slit gap adjustment of the die into automatic control by a heat bolt and manual control by a bolt for manual adjustment, the operation amount of the heat bolt is directly
Since it is the amount of deformation of the movable lip, screw backlash does not affect the automatic control of the slit gap. 2) Compared to the conventional heat bolt material, the alloy steel of constant composition with low thermal conductivity and high tensile strength was used, so the heat radiation to the die body and the adjacent heat bolt was reduced, and it was fed from the heating device. Most of the thermal energy is
Converted to axial thermal expansion of the heat bolt.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front view in the width direction of a die for manufacturing a sheet material according to the present invention, and FIG. 2 is an enlarged sectional view taken along the line AA of FIG. In FIG. 1, 1 is a die body,
A main heating device 2 heats the die body. The die body 1 includes a right die 12 and a left die 1 as shown in FIG.
9 are integrally fixed by a bolt (not shown), and a manifold portion 20 for distributing the molten resin heated by the main heating device 2 in the width direction of the die and a thickness of the extruded film 21 on the joint surfaces of both molds. A slit gap 22 that determines the depth is engraved. The slip gap 22 is a gap formed by one lip block 23 and the other lip block 24 that hang down from the bottom of both molds. 3A in FIG.
11A are heat bolts for adjusting the slit gap 22 screwed into the protruding portion 14a of the right die 12, and a total of nine heat bolts are provided in a row in the width direction of the die. In addition, the slit gap 2 corresponds to these heat bolts 3A to 11A.
2. The same number of manual adjustment bolts 3B to 11 in the width direction of 2
B are provided on the protrusion 14b of the left mold 19 at the same intervals.

In the heat bolt 7A of FIG. 2, the screw 7a at the tip of the heat bolt 7A is fixed to one lip block 23 with a nut 25 while penetrating the protruding portion 14a of the right mold 12, and the other end is bolted. The large-diameter portion 7b on the way is pressed by the hollow screw 26 in the leftward direction in the figure, so that the large-diameter portion 7b is fixed to the protruding portion 14a. Inside the heat bolt 7A, the cartridge heater 16 capable of heating the bolt from room temperature to about 700 ° C. is built in. The heater is an electric wiring 1
Via 5a, the connector 18 and the electric wiring 15b, it is connected to the control device 17 to which the differentiated temperature program for eliminating the unevenness of the sheet thickness is inputted in advance. Therefore, when one of the lip blocks 23 is energized to the cartridge heater 16 of the heat bolt 7A,
Since the large diameter portion 7b is fixed to the protruding portion 14a,
You can move back and forth in the left-right direction in the figure. The above configuration is the same not only for the heat bolt 7A but for all other heat bolts.

On the other hand, in the manual adjustment bolt 7B,
The right end of the bolt 27 is fixed to the other lip block 24 by the nut 23, and the screw at the left end is screwed with the female screw 28 a of the screw 28. The screw 28 is screwed with the bolt 27, and the male screw 28 b provided on the outer periphery of the screw 28 is screwed with the protruding portion 14 b of the left mold 19. This female screw 28
The pitch of a is a so-called differential screw mechanism in which it is smaller than the pitch of the male screw 28b. By rotating the head portion 28c of the screw 28 a desired number of times, the bolt 2
7, that is, the other lip block 24 can be moved back and forth a minute distance in the left-right direction in the drawing. The above configuration is the same not only for the illustrated manual adjustment bolt 7B but also for all other manual adjustment bolts.

In the present embodiment, the heat bolt 3A is used for the die for manufacturing a sheet-like material having the structure shown in FIGS. 1 and 2.
11A, the corrosion-resistant heat-resistant superalloy steel (JIS) according to the present invention, which has both the materials shown in Table 1 and the physical properties shown in Table 2 below.
G4901-1981, sample A) in FIG. 3 and a chromium molybdenum steel (JIS G4105-1) having a higher strength than ordinary steel such as carbon steel for mechanical structure which has been conventionally used.
979, two types of heat bolts of sample B) in FIG. 3, the length of the thermal expansion portion of the shaft portion is 100 mm, and the cartridge heater 1
Main heater 2 is used with heater capacity 6 of 100W.
Heating temperature is set to 300 ° C., and in order to examine the significant difference between the two types of heat bolts, all the manual adjustment bolts 3B to 11B are not operated, and only the heat bolt 7 located in the center of the die 1 is operated. Set the heating temperature of 480 ℃,
FIG. 3 shows the amount of change in the slit gap that occurred under the experimental conditions in which the remaining eight heat bolts were not heated.

[Table 1]

[Table 2] In FIG. 3, the slit gap amount under the test conditions is measured for each of the nine heat bolt positions, the horizontal axis indicates the positions of the heat bolts 3A to 11A, and the distance between the adjacent bolts is 30 mm. The vertical axis plots the ratio of the slit clearance between the heat bolt of sample B and the heat bolt of sample A with reference to the slit clearance generated by the heat bolt of sample B.

As shown in FIG. 3, the linear expansion coefficient α of the heat bolts of the sample A and the sample B are almost the same (see Table 2), but the slit gap (solid line) of the heat bolts of the sample A is The slit gap adjusting ability is about double that of Sample B (broken line), demonstrating the effect of using the alloy steel having the physical properties according to the present invention as the material of the heat bolt.

Further, a long-term continuous test for 30 days was performed using the heat bolt of sample A. When sample B was heated to 500 ° C. or higher, creep was observed in the thermal expansion portion of the shaft portion of the heat bolt by observation after the test. Number 1 according to the phenomenon
Although a permanent sheet strain of 0 μm to several hundred μm was generated and a defective sheet-like substance was generated, the heat bolt using sample A had no permanent strain even when continuously used at a heating temperature of 20 ° C. to 700 ° C. for 30 days. Was not observed.

Further, the thickness unevenness in the width direction of the thermoplastic synthetic resin film produced in the above test (a value obtained by dividing the difference between the maximum value and the minimum value of the thickness by the average value of the thickness) was measured. 4 to 5 when using B heat bolt
%, When the heat bolt of Sample A was used, it was 2-3%, and good results were obtained for the actually produced product. Moreover, a part of the thermal energy input from the cartridge heater 16 conducts heat to the thermoplastic molten resin in the slit gap 22 through the lip block 23 on one side, which causes the viscosity of the resin to be lowered, and the discharge flow rate is reversed. It was possible to solve the conventional problem that the extrusion film 21 was increased and the extruded film 21 was thickened.

Further, since the manual adjusting bolts 3B to 11B provided so as to face the heat bolts 3A to 11A have a deformation amount larger than that of the heat bolts, the film thickness is substantially uniform at the start of film formation. In addition to the effect of the heat bolt described above, a large amount of deformation is obtained, and the degree of freedom in adjusting the slit gap 22 is increased.

[0026]

As described above, in the die for manufacturing a sheet material according to the present invention, the heat bolt for automatic control and the bolt for manual adjustment are separated, and the individual bolts of the heat bolt for automatic control are separated. Since a heating device is provided in the controller, and this heating device is individually controlled by a control device to which a temperature program that is differentiated from other bolts for eliminating the thickness unevenness of the sheet-shaped object is input, Even in the production of products, it is possible to easily control the amount of thermal expansion while eliminating the adverse effect of play on the individual heat bolts. Further, since the heat bolt has a low thermal conductivity and a specific alloy steel having a large tensile strength is used, the creep phenomenon does not occur even if the heat bolt is repeatedly heated, and the slit gap adjusting ability is continuously used. It is possible to obtain a practical die for producing a sheet-like material, which has durability and does not deteriorate. Furthermore, since the thermal expansion amount of the heat bolt can be more clearly ensured with respect to the adjacent heat bolt, a practical die for producing a sheet-like material can be obtained.

The method for producing a sheet material according to the present invention is
When the heat bolt for automatic control and the bolt for manual adjustment are separated, and at least a large slit gap at the time of extrusion disclosure of thermoplastic synthetic resin is required, adjust with the bolt for manual adjustment and make a small slit during extrusion. When adjusting the gap,
Since the heating means of the heat bolt was individually and automatically controlled by the control device in which the temperature program for eliminating the thickness unevenness of the sheet-shaped material was input, in the area above the operation amount of the automatic control of the slit gap by the heat bolt, It can be adjusted easily with the adjusting bolts, and during extrusion there is no rattling of the screw, so the expansion and contraction of the heat bolt due to the increase or decrease in the energy input to the heating device directly leads to the displacement of the lip tip, and the thickness of the sheet is controlled. The property is improved. Therefore, the extruded thickness of the sheet material in the width direction can be easily made constant.

[Brief description of drawings]

FIG. 1 is a front view in the width direction of a die for manufacturing a sheet material according to the present invention.

FIG. 2 is an enlarged sectional view of the die of FIG. 1 taken along the line AA.

FIG. 3 is a diagram showing a ratio of slit gaps generated when the conventional die and the sheet-shaped article manufacturing die according to the present invention are heated to the same temperature, with the conventional die as a reference.

[Explanation of Codes] 1: Die main body 2: Main heating device 3A to 11A: Heat bolt (automatic adjustment bolt) 3B to 11B: Manual adjustment bolt 12: Right die 14a, 14b: Protruding portion 15a, 15b: Electric Wiring 16: Cartridge heater 17: Control device 18: Connector 19: Left die 20: Manifold part 21: Extruded film 22: Slit gap

Claims (5)

[Claims] 1. A die for producing a sheet-like product, which comprises extruding a thermoplastic synthetic resin continuously from the slit gaps of a pair of lip blocks facing each other through a slit gap to produce a sheet-like product. ) A plurality of heat bolts are arranged in one of the lip blocks in the longitudinal direction of the slit gap, and (b) each of the heat bolts is provided for eliminating uneven thickness of the sheet-like material. A heating means connected to a control device to which a temperature program is input is provided, and (c) the other lip block is provided with a plurality of manual adjustment bolts in the longitudinal direction of the slit gap. A die for producing a sheet-like material, which is characterized in that 2. The heat bolt is 20 ° C. to 700 ° C.
Has a thermal conductivity of 5 to 25 kcal / m · hr · ° C,
Moreover, the tensile strength in the above temperature range is 70 to 150 kg /
^2. The die for producing a sheet material according to claim 1, wherein the die is made of an alloy steel having physical properties of mm ² , and further 70% by weight or more of the composition of the alloy steel is Ni. 3. The sheet-shaped product manufacturing die according to claim 2, wherein the heating means of the heat bolt is a cartridge heater built in the bolt near the one lip block. 4. A method for producing a sheet-like article, comprising the step of producing a sheet-like article by continuously extruding a thermoplastic synthetic resin from the slit gaps of a pair of lip blocks facing each other through a slit gap. ) A heat bolt having a built-in heating means is arranged in one lip block of the pair of lip blocks, and a plurality of manual adjustment bolts are arranged in the other lip block along the longitudinal direction of the slit gap. ) In the case where a large slit gap at the time of disclosure of extrusion of the thermoplastic synthetic resin is required, the slit gap is adjusted by the manual adjustment bolt, and (c) a small slit during extrusion of the thermoplastic synthetic resin. When the gap adjustment is required, the heating means for each of the plurality of heat bolts is used as a temperature program for eliminating the thickness unevenness of the sheet-like material. A method for manufacturing a sheet-like material, which is automatically controlled individually by a control device to which is input. 5. The heat bolt is 20 ° C. to 700 ° C.
Has a thermal conductivity of 5 to 25 kcal / m · hr · ° C,
Moreover, the tensile strength in the above temperature range is 70 to 150 kg /
5. The method for producing a sheet-like product according to claim 4, wherein the alloy steel has a physical property of mm ² , and the alloy steel has a composition of 70% by weight or more of Ni.