CN113492088A

CN113492088A - Extrusion process

Info

Publication number: CN113492088A
Application number: CN202110184866.2A
Authority: CN
Inventors: 那须徹雄; 道平创; 三宅雅士
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2020-03-19
Filing date: 2021-02-10
Publication date: 2021-10-12
Anticipated expiration: 2041-02-10
Also published as: TW202140150A; KR20210117924A; CN113492088B; JP2021146291A; JP6722834B1

Abstract

The present invention provides an extrusion method using a die head having a slit formed therein for discharging a fluid, the extrusion method including an adjustment step of adjusting a height of the slit in order to adjust a thickness of a discharge material discharged from the slit, the adjustment step including: the thickness d at a position N from an arbitrary position 1 to an arbitrary position N in a direction orthogonal to the flow direction of the discharge is calculated by using predetermined formulas (1) and (2)_1nSo that the thickness d is calculated by a predetermined formula (3)₁＝{d₁₁...d_1ND target value of thickness_ref＝{d_ref1...d_refNThe difference e between e ═ e₁...e_N-the height of said slot is determined in such a way that it becomes smaller.

Description

Extrusion process

Technical Field

The present invention relates to an extrusion process.

Background

Conventionally, a die head having a slit formed therein for ejecting a fluid is used for manufacturing various products. For example, a coating apparatus called a coater equipped with the die is used to form a coating film on the surface of a thin film or the like. In addition, a die called a T-die for extruding a molten resin in a film form is used for producing a film.

The manufacturing method using the die head includes a step for adjusting the thickness of the discharge discharged from the slit to a desired value. For example, patent document 1 describes a manufacturing method including an adjustment step of adjusting the height of the slit so as to adjust the thickness of the discharge ejected from the slit.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2006 and 346649

Disclosure of Invention

Problems to be solved by the invention

However, conventionally, the thickness of the discharge is adjusted depending on the intuition of the operator, and there is a problem that it is difficult to adjust the thickness of the discharge to a desired thickness. Specifically, when the height of the slit at a position corresponding to the thickness of a part of the discharge is adjusted to change the thickness to a desired value, the thickness may be changed at another position of the slit. That is, there is a problem that even if the thickness of a part of the discharge is adjusted to a desired thickness, the thickness of another part which does not need to be changed is changed.

In the extrusion method using the die, the problem of adjusting the thickness is similarly caused in the case where the thickness of the discharge is not only required to be uniform but also required to be locally changed.

In view of the above problems, an object of the present invention is to provide an extrusion method capable of adjusting the thickness of a discharge relatively easily and with high accuracy.

For resolving questionsScheme of questions

The present inventors have conducted extensive studies and, as a result, have found that the amount of change in the height of the slit and the amount of change in the thickness of the discharge are in a proportional relationship before and after the adjustment of the height of the slit, and have completed the present invention.

The present invention provides an extrusion method using a die head having a slit formed therein for discharging a fluid, the extrusion method including an adjustment step of adjusting a height of the slit in order to adjust a thickness of a discharge material discharged from the slit, the adjustment step including: the thickness d at a position N from an arbitrary position 1 to an arbitrary position N in a direction orthogonal to the flow direction of the discharge is calculated by the following equations (1) and (2)_1nSo that the thickness d is calculated by the following formula (3)₁＝{d₁₁...d_1ND target value of thickness_ref＝{d_ref1...d_refNThe difference e between e ═ e₁...e_N-the height of said slot is determined in such a way that it becomes smaller.

[ mathematical formula 1]

d_1n: the calculated thickness d of the jet after conditioning₁＝{d₁₁...d_1NValue at position n in

d_1ave：d₁＝{d₁₁...d_1NMean value of }

K: constant of proportionality

h_1n: imaginary adjusted height h of the gap₁＝{h₁₁...h_1NValue at position n in

h_1ave：h₁＝{h₁₁...h_1NMean value of }

h_0n: height h of the gap before adjustment₀＝{h₀₁...h_0NValue at position n in

h_0ave：h₀＝{h₀₁...h_0NMean value of }

d_0n: thickness d of the jet before adjustment₀＝{d₀₁...d_0NValue at position n in

d_0ave：d₀＝{d₀₁...d_0NMean value of }

v: viscosity index of the fluid

[ mathematical formula 2]

e_n＝(d_refn-d_1n)···(3)

e_n: the difference e ═ e₁...e_NValue at position n in

d_refn: a target value d of the thickness of the jet_ref＝{d_ref1...d_refNValue at position n in

With this structure, if the height h of the gap before adjustment is determined₀Thickness d of the discharge before adjustment₀And the value of the proportionality constant K calculated by the equation (2), based on the calculated thickness d calculated by the equation (1)₁Target value d of thickness_refThe difference e between the heights determines the height of the gap, and therefore the thickness of the jet can be adjusted relatively easily and accurately.

In the extrusion method of the present invention, it is preferable to obtain the value obtained by making the difference e ═ e { e } represented by the following formula (4)₁...e_NH is the smallest sum of squares₁＝{h₁₁...h_1NAccording to h₁To determine the height of the gap.

[ mathematical formula 3]

By usingThis structure is based on h that minimizes the sum of squares of the differences e expressed by the formula (4)₁The height of the slit is determined, and therefore the thickness of the discharge can be adjusted more accurately.

ADVANTAGEOUS EFFECTS OF INVENTION

As described above, according to the present invention, it is possible to provide an extrusion method capable of adjusting the thickness of a jet relatively easily and with high accuracy.

Drawings

Fig. 1 is a schematic perspective view of a die used in an extrusion method of one embodiment.

Fig. 2 is an exploded perspective view of the die of fig. 1.

FIG. 3 is a diagrammatic sectional view through line III-III of the die of FIG. 1.

Fig. 4 is a graph for comparing the change in the height of the gap and the thickness of the coating film before and after the adjustment in example 1.

Fig. 5 is a graph for comparing changes in the thickness of the coating film before and after the adjustment of comparative example 1.

Fig. 6 is a graph for comparing the change in the height of the gap and the thickness of the coating film before and after the adjustment in example 2.

Description of the reference numerals

1: coating machine; 10: a die head; 11: gap, 110: an opening; 111: an upstream-side end; 13: a discharge section; 20: a 1 st module; 21: a passage; 22: a chamber; 30: a 2 nd module; 40: a shim member; 42: an opening; 50: an adjustment mechanism; 51: a slit; 52: an adjusting screw; 521: an outer screw; 522: and (5) internal screws.

Detailed Description

Hereinafter, an extrusion method according to an embodiment of the present invention will be described with reference to the drawings.

The extrusion method of the present embodiment is a method as follows: a coating apparatus referred to as a coater 1 as shown in fig. 1 to 3 is used to apply a coating liquid as a fluid material to the surface of an object to be coated such as a film F to form a coating film as a jet, and the coating film is formed on the surface of the film F.

The coater 1 includes a die 10 having a slit 11 for discharging the coating liquid. The die 10 is configured to apply the coating liquid discharged from the slit 11 to an object to be coated such as a film F that is supported by a roller member or the like and that travels so as to approach the opening 110 of the slit 11, thereby forming a coating film on the surface of the film F. The die head 10 is formed such that the discharge portion 13 of the opening 110 formed with the slit 11 projects toward the object to be coated such as the film F. In the present embodiment, the die 10 has the 1 st block 20 (lower block in the figure) and the 2 nd block 30 (upper block in the figure), and the slit 11 is formed between the respective blocks. Hereinafter, the direction in which the film F or the coating film flows is sometimes referred to as the MD direction, and the direction orthogonal to the MD direction is sometimes referred to as the TD direction. The height of the opening 110 of the slit 11 is referred to as the height h of the slit 11.

The die head 10 of the present embodiment further includes an adjustment mechanism 50 for adjusting the height h of the slit 11 on the 2 nd block 30 side. In the present embodiment, the adjustment mechanism 50 includes: a slit 51 disposed in the 2 nd module 30 along the width direction of the slit 11; and a plurality of adjustment screws 52 which adjust the interval of the slits 51 to thereby adjust the height h of the slit 11. The plurality of adjustment screws 52 are aligned along the extending direction of the slit 51 (in other words, along the width direction of the slit 11). By rotating the adjusting screws 52 and moving them forward or backward, the gap between the slits 51 is enlarged or reduced, and the height h of the gap 11 is enlarged or reduced accordingly.

As the adjustment screw 52, for example, a differential screw 52 can be preferably used. This facilitates fine adjustment of the height h of the slit 11. The differential screw 52 has an outer screw 521 formed to be hollow and an inner screw 522 formed to be coupled with an inner screw of the outer screw 521. The outer screw 521 and the inner screw 522 are formed such that the respective pitches have different sizes. Thus, when the outer screw 521 is rotated by 1 rotation, the slit 51 expands or contracts by the pitch difference between the outer screw 521 and the inner screw 522.

As shown in fig. 2, in the present embodiment, the die 10 has a plate-like shim member 40, and the shim member 40 is arranged to be sandwiched between the 1 st block 20 and the 2 nd block 30. The spacer member 40 is formed in a C shape so as to open toward the opening 110 of the slit 11. By adjusting the width of the opening 42 of the shim member 40 of the die 10, the width of the coating film can be adjusted.

The gap 11 is formed so that the height h can be adjusted to 0.01mm to 5 mm. The width of the slit 11 is usually set to 200mm to 5000 mm.

The number of the adjustment screws 52 is usually 3 to 90. The distance between the centers of the rotation axes of the adjustment screws 52 is usually set to 10mm to 400 mm. The distances between the centers of the rotational axes are preferably equal distances each other, but may be different distances from each other. In the present embodiment, the adjustment mechanism 50 has N adjustment screws 52. Hereinafter, the positions of the slit 11 and the position of the coating film corresponding to the 1 to N adjustment screws 52 are referred to as positions 1 to N.

As shown in fig. 3, the 1 st block 20 has a chamber 22 for temporarily accumulating the coating liquid supplied from an accommodating portion (not shown) accommodating the coating liquid through a passage 21. The chamber 22 is formed in a concave shape. In addition, the chamber 22 is connected to the slit 11.

At least the 2 nd module 30 of the 1 st module 20 and the 2 nd module 30 is made of a material that can be elastically deformed by adjusting the pressing force of the screw 52 or the like. Typically, the 1 st and 2

nd modules

20, 30 are made of a metal such as stainless steel. The spacer member 40 is generally made of a metal foil such as stainless steel or brass, or a plastic film such as polyethylene terephthalate.

Examples of the coating liquid include a polymer solution. The viscosity of the coating liquid is usually set to 0.0005 pas to 200 pas, preferably 0.001 pas to 100 pas. Further, the viscosity was measured by a rheometer (manufactured by HAAKE). In addition, the conditions were such that the shear rate was 1[1/s ] and the temperature was 20 ℃.

Next, the extrusion method of the present embodiment will be described in detail.

The extrusion method of the present embodiment is a coating method using a coater 1 for forming a coating film on the surface of an object to be coated such as a film F. In order to adjust the thickness d of the coating film formed on the surface of the film F by discharging the coating liquid from the slit 11, this coating method includes an adjustment step P of adjusting the height h of the slit 11 and an extrusion step of extruding the coating liquid after the adjustment step P. In the present embodiment, the flow rate of the coating liquid supplied from the housing section of the coater 1 is made constant.

In the present embodiment, the flow rate of the coating liquid is preferably a mass flow rate. The flow rate of the coating liquid is determined to include the following cases: in the steady operation, the value calculated as [ maximum flow rate-minimum flow rate ]/average flow rate is 0.2 or less, preferably 0.1 or less.

The adjustment step P includes: a data acquisition step P1 of adjusting the height h of the gap 11 from the position 1 to the position N before adjustment in the data acquisition step P1₀＝{h₀₁...h_0NAnd the thickness d of the coating film at the position 1 to the position N before adjustment₀＝{d₀₁...d_0N-performing a measurement; a constant calculation step P2 of calculating a proportionality constant K that relates the amount of change in the height h of the slit 11 and the amount of change in the thickness d of the coating film by the following formula (2) in the constant calculation step P2; and a height determining step P3 of calculating a thickness d of the coating film at a position N from the position 1 to the position N by the following formula (1) in the height determining step P3_1nSo that the thickness d is calculated by the following formula (3)₁＝{d₁₁...d_1ND is a target value of the thickness of the coating film_ref＝{d_ref1...d_refNThe difference e between e ═ e₁...e_NThe height h of the slit 11 is determined in such a manner that it becomes smaller.

[ mathematical formula 4 ]

[ math figure 5 ]

e_n＝(d_refn-d_1n)···(3)

d_1nIndicates the calculated thickness d of the coating film after adjustment₁＝{d₁₁...d_1NThe value at position n in.

d_1aveDenotes d₁＝{d₁₁...d_1NMean value of. In the present embodiment, the flow rate of the coating liquid is constant, and therefore, d may be regarded as_1ave＝d_0ave。

K represents a proportionality constant.

h_1nShows the height h of the imaginary adjusted gap 11₁＝{h₁₁...h_1NThe value at position n in.

h_1aveRepresents h₁＝{h₁₁...h_1NMean value of.

h_0nIndicating the height h of the gap before adjustment₀＝{h₀₁...h_0NThe value at position n in.

h_0aveRepresents h₀＝{h₀₁...h_0NMean value of.

d_0nIndicates the thickness d of the discharge before conditioning₀＝{d₀₁...d_0NThe value at position n in.

d_0aveDenotes d₀＝{d₀₁...d_0NMean value of.

v represents the viscosity index of the coating liquid.

e_nRepresents the difference e ═ e₁...e_NThe value at position n in.

d_refnA target value d representing the thickness of the jet_ref＝{d_ref1...d_refNThe value at position n in.

The above formula (1) is derived from the following formula (5). In the following formula (5), the left side indicates the amount of change in the thickness d of the coating film, and the right side parentheses indicate the amount of change in the height h of the slit 11, each of which is related by the proportionality constant K.

[ mathematical formula 6 ]

The above formula (5) is based on the following formula (6) which is established when the coating liquid is assumed to be a newtonian fluid.

[ mathematical formula 7 ]

Q represents the flow rate of the newtonian fluid flowing in the slit 11.

W represents the coating width.

Δ P represents the pressure difference (P1-P2) between the pressure P1 of the Newtonian fluid at the upstream side end 111 of the slit 11 and the pressure P2 of the Newtonian fluid at the opening 110.

μ denotes viscosity.

L denotes the length of the slit, i.e., the distance from the upstream-side end 111 to the opening 110.

As described above, equation (6) shows that the rate of change dQ/Q of the flow rate of newtonian fluid is proportional to the rate of change dh/h of the height h of the slit 11. The above equation (1) is derived by considering the rate of change dQ/Q of the flow rate in equation (6) as the rate of change of the film thickness d of the coating liquid.

The above formula (2) is derived from the following formula (7) in which the above formula (6) is rewritten in the case of being a non-newtonian fluid.

[ mathematical formula 8 ]

In the above formula (2), v represents a viscosity index of the coating liquid. Generally, the viscosity of a liquid such as a coating liquid is represented by the following approximate formula (8). In the present embodiment, the viscosity index v obtained by the above approximate formula based on the viscosity data of the coating liquid measured by the rheometer can be used instead of formula (2).

[ mathematical formula 9 ]

μ＝η·γ^v-1···(8)

μ represents the viscosity [ Pa.s ] of the coating liquid.

Eta represents the zero shear viscosity [ Pa · s ] of the coating liquid.

Gamma denotes the shear rate [1/s ].

v represents the viscosity index of the coating liquid.

[ data acquisition Process P1]

In the data acquisition step P1, the thickness d of the coating film at the height h of the slit 11 before adjustment is measured. Namely, the height h of the gap 11 from the position 1 to the position N before adjustment₀＝{h₀₁...h_0NAnd the thickness d of the coating film at the position 1 to the position N before adjustment₀＝{d₀₁...d_0NThe measurement is carried out.

As the measurement values of the height h of the slit 11 at the position 1 to the position N, the measurement values of the height of the portion corresponding to the adjustment screw 52 can be adopted. That is, the height h of the slit 11 at the same position as the adjustment screw 52 in the TD direction is used as a measurement value.

As the measured values of the thickness d of the coating film at the positions 1 to N, the thickness d of the coating film at the same position as the adjustment screw 52 in the TD direction can be adopted. The thickness d of the coating film is measured, for example, by a linear gauge (manufactured by kawasaki corporation).

In the data acquisition step P1, h is also calculated₀＝{h₀₁...h_0NMean value h of }_0aveAnd d₀＝{d₀₁...d_0NMean value of d_0ave。

[ constant calculation Process P2]

In the constant calculation step P2, a proportionality constant K that relates the amount of change in the height h of the slit 11 to the amount of change in the thickness d of the coating film is calculated by the above equation (2). The proportional constant K is a constant used in the following height determining step P3 in place of the formula (1).

[ height determining Process P3]

In the height determining step P3, the thickness d at the position N among the positions 1 to N is calculated by the above equation (1)_1nSo that the thickness d is calculated from the above equation (3)₁＝{d₁₁...d_1ND target value of thickness_ref＝{d_ref1...d_refNThe difference e between e ═ e₁...e_NCalculating the height h of the gap at the positions 1-N after adjustment₁＝{h₁₁...h_1N}。

In the present embodiment, for h₁＝{h₁₁...h_1NAnd a least square method of making a difference e ═ e { e } represented by the following formula (4)₁...e_NThe sum of squares is calculated so as to minimize the sum. E.g. h₁＝{h₁₁...h_1NThe arithmetic operation can be calculated by giving an arbitrary initial value and using an EXCEL (registered trademark) solver. And, based on h₁＝{h₁₁...h_1NThe value of h determines the height h of the adjusted gap 11₂＝{h₂₁...h_2N}. As height h of adjusted gap 11₂＝{h₂₁...h_2NH can be directly adopted₁＝{h₁₁...h_1NThe value of h can also be used₁＝{h₁₁...h_1NThe value of which is used as a reference and fine-tuned.

[ MATHEMATICAL FORMULATION 10 ]

As described above, according to the extrusion method of the present embodiment, the height h of the slit 11 before adjustment is determined₀＝{h₀₁...h_0ND, thickness of coating liquid before adjustment₀＝{d₀₁...d_0NThe value of K, which is a proportional constant calculated by the equation (2), and the calculated thickness d calculated by the equation (1)₁＝{d₁₁...d_1ND target value of thickness_ref＝{d_ref1...d_refNThe difference e between e ═ e₁...e_NH to determine the height h of the slot 11₁＝{h₁₁...h_1NBased on h₁＝{h₁₁...h_1NThe value of h determines the height h of the adjusted gap 11₂＝{h₂₁...h_2NTherefore, the thickness of the coating liquid can be adjusted relatively easily and with good precision. The extrusion method of the present embodiment is excellent not only in adjusting the thickness d of the coating liquid to a target uniform thickness, but also in adjusting the thickness d of the coating liquid to a target non-uniform thickness.

The extrusion method of the present invention is not limited to the above embodiment. The extrusion method of the present invention is not limited to the above-described effects. The extrusion method of the present invention can be variously modified within a range not departing from the gist of the present invention.

For example, although the coating method using the coater 1 is described in the above embodiment, a method of forming a resin film using a T-die or the like for extruding a molten resin may be used. In this case, the viscosity of the molten resin is preferably 1000 pas to 5000 pas.

In the above embodiment, the height h of the slit 11 is adjusted by the adjusting mechanism 50 having the slit 51 and the adjusting screw 52, but the present invention is not limited thereto. As another adjusting mechanism 50, a heat bolt may be used instead of the adjusting screw 52. In addition, for example, the spacer member 40 and each module may be machined to adjust the height h of the gap. The data acquisition step P1 and the constant calculation step P2 may be performed using a trial-production coater 1, and the coater 1 having a height h set in the height determination step P3 to obtain a desired thickness d of the coating film may be manufactured.

In the above embodiment, the least square method is shown as the approximation method, but in addition to this, for example, the newton method may be used.

[ examples ] A method for producing a compound

The present invention will be further described below by way of examples.

In this example, a method of forming a coating film using a coater was examined.

[ coating apparatus ]

The coater used in this example was made of stainless steel, and a gap of 1300mm in width was formed between the 1 st block and the 2 nd block. In addition, as a height adjusting mechanism of the slit, this coater has a slit provided in the 2 nd block and 26 (i.e., N is 26, and the distance between the centers of the rotation axes: 50mm and constant) adjusting screws arranged in the entire TD direction.

[ coating conditions ]

An acrylic polymer dissolved in a solvent as a coating liquid was applied to the surface of a thin film as an object to be coated under the coating conditions shown in table 1, thereby forming a coating film composed of an acrylic polymer as an ejection material.

[ TABLE 1]

[ example 1]

In example 1, a method of adjusting the height of the slit so that the thickness of the coating film is changed from a non-uniform state to a uniform state is exemplified.

(data acquisition step P1)

For the height h of the gap from the position 1 to the position 26 before adjustment₀＝{h₀₁...h_{0_26}And the thickness d of the coating film at the positions 1 to 26 before adjustment₀＝{d₀₁...d_{0_26}The measurement is carried out. The measurement results are shown in table 2.

(constant calculation Process P2)

The viscosity index v of the coating liquid used in the present example was calculated by the above equation (8), and the proportionality constant K was calculated by substituting the viscosity index v into the above equation (2). As shown in table 2, K is 4.89.

(height determining step P3)

The thickness of the coating film shown in Table 2 was setTarget value d of_ref＝{d_ref1...d_ref26By the least square method using the above formulas (1), (3) and (4), so that the calculated thickness d of the positions 1 to 26₁＝{d₁₁...d_{1_26}D target value of thickness_ref＝{d_ref1...d_ref26The difference e between e ═ e₁...e₂₆Calculating the adjusted gap heights h at the positions 1 to 26 so that the sum of the squares thereof becomes the minimum₁＝{h₁₁...h_{1_26}}. The calculated results are shown in table 2 below.

(extrusion Process)

Height h as gap₂＝{h₂₁...h_2NH calculated above is adopted₁＝{h₁₁...h_{1_26}And forming a coating film on the thin film. The results obtained by measuring the adjusted thickness are shown in table 2 and fig. 4.

As shown in table 2 and fig. 4, the thickness of the coating film before adjustment was in a non-uniform state in the vicinity of the width 255mm and in the vicinity of the width 1125mm, and the thickness of the coating film after adjustment was adjusted to be in a substantially uniform state as a target in the entire width direction.

[ TABLE 2]

Comparative example 1

In comparative example 1, the result of adjusting the gap height by a skilled worker without using the method is exemplified. In comparative example 1, h₀、d₀And d_refThe value of (b) was set to the same value as in example 1. In addition, based on h₀And d₀The height of the gap was adjusted 5 times using an adjusting screw. The results are shown in table 3 and fig. 5.

As shown in table 3 and fig. 5, the target value was deviated in the entire width direction. In the entire width direction, the thickness originally smaller than the target value becomes larger than the target value, and the thickness originally larger than the target value becomes smaller than the target value, and it can be seen that it is difficult to adjust by the experience of the operator.

[ TABLE 3]

Table 4 below summarizes the accuracy of the thickness of the coating film before and after the adjustment in example 1 and comparative example 1. The thickness accuracy is calculated by [ maximum thickness-minimum thickness ]/average thickness × 100. As is clear from the results in table 4, the thickness of the coating film can be easily and accurately adjusted by the extrusion method of example 1 as compared with comparative example 1.

[ TABLE 4 ]

	Example 1	Comparative example 1
			Adjusting screw adjusting times (times)	1	5
Thickness precision before adjustment (%)	16.10	16.10
			Adjusted thickness precision (%)	0.63	5.46

[ example 2]

In example 2, a method of adjusting the height of the slit so that the thickness of the coating film is changed from a uniform state to a non-uniform state is exemplified. The coating conditions were those shown in table 5. The results are shown in table 6 and fig. 6.

[ TABLE 5 ]

As shown in table 6 and fig. 6, the thickness of the coating film after adjustment was adjusted to be approximately in a target uneven state in the entire width direction.

[ TABLE 6 ]

Claims

1. An extrusion method using a die having a slit formed therein for discharging a fluid, wherein,

the extrusion method includes an adjustment step of adjusting the height of the slit in order to adjust the thickness of the discharge material discharged from the slit,

the adjusting step includes the steps of: the thickness d at a position N from an arbitrary position 1 to an arbitrary position N in a direction orthogonal to the flow direction of the discharge is calculated by the following equations (1) and (2)_1nSo that the thickness d is calculated by the following formula (3)₁＝{d₁₁...d_1ND target value of thickness_ref＝{d_ref1...d_refNThe difference e between e ═ e₁...e_N-the height of said slot is determined in such a way that it becomes smaller,

d_1ave：d₁＝{d₁₁...d_1NMean value of }

K: constant of proportionality

h_1ave：h₁＝{h₁₁...h_1NMean value of }

h_0ave：h₀＝{h₀₁...h_0NMean value of }

d_0ave：d₀＝{d₀₁...d_0NMean value of }

v: viscosity index of the fluid

e_n＝(d_refn-d_1n)…(3)

e_n: the difference e ═ e₁...e_NValue at position n in

d_refn: a target value d of the thickness of the jet_ref＝{d_ref1...d_refNThe value at position n in.

2. The extrusion process of claim 1,

obtaining a difference e ═ e { e } expressed by the following formula (4)₁...e_NThe sum of squares becomesMinimum h₁＝{h₁₁...h_1NAccording to h₁To determine the height of the gap or gaps,