JP2002240126A - Method for forming resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control defects such as a neck-in and the thickening of both ends of a resin film associated with the neck-in even when production conditions such as resin conditions and operation conditions are changed. SOLUTION: In a method for forming the resin film 11 by extruding the molten resin from an extrusion die 12, the second resin 11B, the elongation viscosity of which is larger than that of the first resin 11A forming the middle part in the widthwise direction of the resin film 11 and which forms both ends in the widthwise direction of the resin film 11, is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a resin film, and more particularly, to a method for suppressing a neck-in phenomenon when extruding a resin from an extrusion die to form a resin film.

[0002]

2. Description of the Related Art In general, a resin film is formed by extruding a resin from an extrusion die, and the resin film is used for producing a film-like material or a film laminate in which the resin film is laminated or coated on a support. A phenomenon called a neck-in occurs in which the width of the resin film extruded from the die becomes narrower than the extrusion width. In addition, there is a problem that the film thickness at both ends in the width direction of the resin film becomes larger than the film thickness at the central portion. Furthermore, when a resin film is formed at a high speed by increasing the production line speed, a film swing phenomenon occurs due to instability of both ends in the width direction of the resin film, and the film width becomes constant. However, there is also a problem that the yield is lowered. In this case, there is a technique of mainly laminating the resin in the width direction for the purpose of recycling, but when laminating the resins having different physical properties, the resin between the resin at the center of the resin film and the resin at both ends is laminated. There is a problem of film separation in which the film is separated.

That is, in forming a resin film by an extrusion die, there are mainly a problem of neck-in and a resultant increase in the film thickness of both ends of the resin film, a problem of film sway, and a problem of resin at both ends and a central portion of the resin film. There is a problem of film peeling due to different physical properties, and measures to improve these have been demanded. These problems occur not only when the resin is extruded from the extrusion die but also when the coating liquid is discharged from the extrusion die.

Conventionally, as a countermeasure against the above problem, a method of improving material properties by mixing a plurality of materials (Japanese Patent Publication No. 64-3655, Japanese Patent Publication No. 5-82806), the flow of resin in an extrusion die. (Japanese Patent Publication No. 6-61819, Japanese Patent Publication No. 64-64822)
JP-A-5-33134), and a method of cooling both end portions of a resin film extruded from an extrusion die.

[0005]

However, the method for improving the physical properties of a material has a drawback that it is not versatile because it is necessary to add an appropriate additive for each material. The method of changing the flow of the resin in the extrusion die using a forming plate is effective in suppressing neck-in, but has a disadvantage in that it is not effective in film shake. Further, the method of cooling both ends of the resin film extruded from the extrusion die has a disadvantage that a stable effect cannot be obtained when the line speed is increased.

The present invention has been made in view of such circumstances, and even when manufacturing conditions such as resin conditions and operating conditions are changed, the thickness of the neck-in and the thickness of both ends of the resin film accompanying the neck-in are increased. And a method for forming a resin film that does not separate even if the physical properties of the resin at both ends and the central portion of the resin film are different from each other. The purpose is to:

[0007]

According to a first aspect of the present invention, there is provided a resin film forming method for extruding a molten resin from an extrusion die to form a resin film. The resin forming both ends in the width direction of the film is characterized by using a resin having a higher elongational viscosity than the resin forming the center portion in the width direction of the resin film.

Thus, it is possible to suppress the neck-in and the accompanying increase in the film thickness at both ends of the resin film. In addition, it is possible to suppress film fluctuation in which the width of the resin film fluctuates with the effect of suppressing neck-in.

According to a second aspect of the present invention, there is provided a method of forming a resin film by extruding a resin in a molten state from an extrusion die to achieve the above object. The resin forming the portion is characterized by using a resin having a lower MFR than the resin forming the central portion in the width direction of the resin film.

As a result, it is possible to suppress the neck-in and the accompanying increase in the film thickness at both ends of the resin film. In addition, it is possible to suppress film fluctuation in which the width of the resin film fluctuates with the effect of suppressing neck-in.

According to a third aspect of the present invention, there is provided a resin film forming method for extruding a molten resin from an extrusion die to form a resin film. The resin forming the portion has a larger extensional viscosity than the resin forming the central portion in the width direction of the resin film,
In addition, a resin having a small MFR is used.

As a result, neck-in and film swing can be further suppressed.

The MFR means that the thermoplastic resin is 230 °
The number of g (grams) of the amount extruded from an orifice 2.1 mm in diameter and 8 mm in length when subjected to 2310 g force (44 ps) with C (measurement method is JIS K
Generally, a resin having a higher MFR has better fluidity and processability at the time of melting, but has a lower tensile strength and the like.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the resin forming both ends of the resin film is joined so as to be wrapped in the resin forming the central portion, and the extruding is performed. It is characterized by being extruded from a die.

Thus, not only can neck-in and film fluctuation be suppressed further, but also film separation can be prevented even if the physical properties of the resin at both ends and the center of the resin film differ to some extent.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for forming a resin film according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram showing an example of a manufacturing apparatus to which the method for forming a resin film according to the present invention is applied.
An example of an apparatus for manufacturing a film-like laminate in which a resin film is laminated on a support will be described.

As shown in FIG. 1, below the extrusion die 12 for extruding a resin in a molten state to form a resin film 11,
The cooling roller 14 and the nip roller 16 are arranged adjacent to each other in parallel, and the nip roller 1
On the opposite side of 6, a peeling roller 18 is arranged adjacent to and parallel to the cooling roller. After the resin film 11 extruded from the extrusion die 12 is adhered to a belt-shaped support 22 conveyed from the upstream side, the resin film 11 passes between the cooling roller 14 and the nip roller 16 and between the cooling roller 14 and the peeling roller 18. The roller travels while contacting the peripheral surface of the cooling roller 14 and separates from the cooling roller at the position of the peeling roller 18. Thereby, the film-like laminated body 27 is manufactured. As the support 22, paper, resin, or metal can be used depending on the required film-like laminate 27. Further, as the resin forming the resin film, a known thermoplastic resin such as a polyolefin-based resin such as polyethylene and polypropylene can be used.

FIG. 2 is a schematic diagram of the extrusion die 12.
(A) is a front view, (b) is a side view.

As shown in FIG. 2, the extrusion die 12 mainly converts the resin supplied into the extrusion die 12 into the extrusion die 12.
2 that expands in the width direction (width direction of the resin film)
8, a slit 30 for extruding resin from the manifold 28 as a resin film 11 to the outside, a main flow path 32 through which a first resin 11A forming a central portion in the resin film width direction flows, and both ends in the resin film width direction are formed. And the branch flow paths 34, 34 through which the second resin 11B flows. 1st resin 11A
Is extruded from the slit discharge port 30A in a state where the two are combined with the second resin 11B and the two resins are combined. Note that the first resin 11A and the second resin 11B may join in the extrusion die 12 as shown here, or may join before being supplied to the extrusion die 12. As a result, the resin is extruded from the extrusion die 12 as a resin film 11, and the extruded resin film 11 has a central portion at the first resin 11.
A, and both ends are formed of the second resin 11B. In this case, it is preferable to use a resin having a higher elongational viscosity than the first resin as the second resin 11B. Further, it is preferable to use a resin having a lower MFR than the first resin 11A as the second resin. In addition, the first resin 1
1A may form a single layer with a single resin or a multiple layer with a plurality of resins, and may contain an inorganic pigment, an additive, or the like. Further, the second resin 11B is at least one kind of resin, and may include an additive or the like,
Considering the trimming loss (loss caused by cutting the ears at both ends of the product in a later step), it is preferable that the resin is a single resin.

FIG. 3 is a diagram schematically showing a cross section of the resin film 11 extruded from the extrusion die 12 in the width direction. The first resin 11A forming the central portion in the width direction of the resin film, This shows the relationship with the second resin 11B forming both ends in the film width direction.

FIG. 3A shows a case where the second resin 11B is joined to both sides in the width direction of the first resin 11A so as to be adjacent to each other. FIG. 3B shows a case where the first resin 11A and the second resin 11B are joined so as to be enveloped. When FIG. 3A and FIG. 3B are compared, FIG.
As shown in (b), the first resin 11A and the second resin 11B
Can be prevented from being separated from each other even if the physical properties of the first resin 11A and the second resin 11B differ to some extent.

In FIG. 3 (b), the first resin 11A
Is wrapped around the second resin 1B.
Although 1B is an example in which two islands are formed at both ends in the width direction of the first resin 11A, one island may be formed or two or more islands may be formed. Good. In order to form two or more islands, the number of branch flow paths 34 to which the second resin 11B is supplied may correspond to the number of islands.

Next, the manufacturing method of the present invention will be described using the apparatus 10 for manufacturing a film-like laminate configured as described above.

First resin 11 supplied to extrusion die 12
A and the second resin 11B are joined together at a temperature equal to or higher than the melting point of each resin, and the two resins are united. The central portion is formed of the first resin 11A and both ends are formed of the second resin 11B. The resin film 11 is extruded from the slit discharge port 30A. Resin film 1 extruded from extrusion die 12
1 is oxidized by an oxidizing gas such as air or ozone so as to obtain sufficient adhesion with the support 22 transported from the upstream, and then sandwiched between the cooling roller 14 and the nip roller 16. Laminated on the support 22.
After being sufficiently cooled by the cooling roller 14, it is separated from the cooling roller 14 by the separation roller 18. Thus, a film-like laminate 27 in which the resin film 11 is laminated on the support 22 is manufactured.

In the present invention, when the resin film 11 is formed by the extrusion die 12 at the time of manufacturing the film-like laminate 27, the second resin 11B forming both ends in the width direction of the resin film 11 is made of resin. Since a resin having a larger extensional viscosity than the first resin 11A forming the central portion in the width direction of the film is used, neck-in can be effectively suppressed. In addition, as the effect of suppressing the neck-in increases, the film fluctuation in which the width of the resin film 11 fluctuates can be more effectively prevented. In this case, the upper limit of the elongational viscosity is the first resin 11
When expressed as a ratio of the extensional viscosity of the second resin 11B to the extensional viscosity of A (hereinafter referred to as “extensional viscosity ratio”), it is preferably 10 times or less. This is because, if the elongational viscosity ratio exceeds 10 times, the difference in physical properties between the first resin 11A and the second resin 11B becomes too large, which is likely to cause film separation.

There are various possible causes of the neck-in. In the case of manufacturing a film-like laminate, the neck-in changes the speed of the resin film 11 when changing from the speed extruded from the extrusion die 12 to the speed taken up by the cooling roller 14. It is considered that the resin film 11 contracts due to the velocity distribution in the width direction. On the other hand, the degree of shrinkage varies depending on the viscosity of the resin. Viscosity includes shear viscosity and elongational viscosity.
When simply saying viscosity, it refers to shear viscosity, but it has been found that the relationship with the degree of shrinkage is more closely related to elongational viscosity. Therefore, the second resin 11B, which has a higher extensional viscosity than the first resin 11A forming the central portion in the width direction of the resin film 11 and is less likely to cause neck-in, is disposed at both ends of the resin film 11 so as to form a neck. It was found that in could be significantly reduced. In this case, the elongational viscosity is not always increased by increasing the shear viscosity, so it is important to control neck-in by managing the elongational viscosity.

The neck-in can also be effectively suppressed by using a resin having a smaller MFR than the first resin 11A as the second resin 11B.
In addition, as the effect of suppressing the neck-in increases, the film fluctuation in which the width of the resin film 11 fluctuates can be more effectively prevented.
In this case, the lower limit of the MFR is the MFR of the first resin 11A.
(Hereinafter referred to as “MFR”).
Ratio ") is preferably 1/10 or more. This is because, when the MFR ratio is less than 1/10, the difference in physical properties between the first resin 11A and the second resin 11B becomes too large, which is likely to cause film separation.

Further, the second resin 11B is the first resin 1B.
By merging so as to be wrapped in 1A, it is possible to prevent the first resin 11A and the second resin 11B from being separated from each other even if their physical properties are somewhat different. In this case, FIG.
If the second resin 11B is divided into a plurality as shown in FIG.
Since the contact area between the second resin 11B and the first resin 11A can be increased, the resin film 11 can be formed at a high speed,
Even when the difference in physical properties between the second resin 11B and the first resin 11A is large to some extent, film separation can be effectively prevented. However, if the number of divisions of the second resin 11B is too large, the uniformity of the flow rate deteriorates and the processing of the branch flow path 34 becomes difficult, so that the first resin 11A and the second resin 11
It may be set appropriately in consideration of the physical properties of B.

Also, as in the present embodiment, the resin film 11
In the case of manufacturing a film-like laminate in which the resin film is laminated on the support 22, if the film thickness of both ends of the resin film is large, the cooling roller 14 does not sufficiently cool the film, and a trouble that the resin film does not peel off from the cooling roller 14 easily occurs. According to the present invention, the temperature can be reduced only at both ends of the resin film 11 and the film thickness can be reduced, so that such troubles can be eliminated.

In this embodiment, an example of manufacturing a film-like laminate in which the resin film 11 is laminated on the support 22 has been described. However, the present invention relates to a film-forming process for manufacturing a film-like material, a coating solution, Can also be applied in a coating step in which is applied in the form of a film to the support.

[0032]

Next, specific examples of the method for forming a resin film according to the present invention will be described. The resins subjected to the test are as follows. The line speed was set to 200 m / min and 420 m / min. Comparative Example 1 A low-density polyethylene melt having an MFR of 10 g / 10 min, a dimensionless elongational viscosity of 1.0, and a density of 0.917 g / cm ³ mixed with 10 wt% of titanium oxide was extruded from an extrusion die. Extruded. That is, the test was performed using only the first resin and not using the second resin. The elongational viscosity is measured by a rheometer. When the elongation speed is 10 (1 / sec), the representative viscosity is set to 1000 pa · s, and is represented dimensionlessly in this embodiment. (Comparative Example 2) As a second resin forming both ends in the resin film width direction, a first resin having an MFR of 20 g / 10 min (MFR ratio 2) and an elongational viscosity forming a widthwise central portion of the resin film. A resin having an elongational viscosity of 1/3 times (an elongational viscosity ratio of 1/3) was used. Then, a central portion was formed of the first resin and both end portions were extruded from the slit discharge port of the extrusion die as a resin film formed of the second resin. That is, the second resin of Comparative Example 2 has a higher MFR and a lower elongational viscosity than the first resin, and does not satisfy the present invention. The cross section of the resin film when the first resin and the second resin merged was such that the second resin was wrapped in the first resin as shown in FIG. 3B. (Example 1) As a second resin forming both ends in the resin film width direction, a first resin having an MFR of 8 g / 10 min (MFR ratio 4/5) and an elongational viscosity forming a central portion in the resin film width direction is used. A resin having an elongational viscosity of 1.2 times (elongational viscosity ratio: 1.2) was used. Then, a central portion was formed of the first resin and both end portions were extruded from the slit discharge port of the extrusion die as a resin film formed of the second resin. That is, the second resin of Example 1 has a lower MFR and a higher elongational viscosity than the first resin, and satisfies the present invention. Note that the cross-sectional shape of the resin film is the same as in Comparative Example 2. (Example 2) As a second resin forming both ends in the resin film width direction, the MFR is 12 g / 10 min (MFR ratio 1.2)
In addition, a resin having an extensional viscosity of 1.2 times (elongational viscosity ratio 1.2) the extensional viscosity of the first resin forming the central portion in the width direction of the resin film was used. Then, a central portion was formed of the first resin and both end portions were extruded from the slit discharge port of the extrusion die as a resin film formed of the second resin. That is, the second resin of Example 2 has a case where the MFR does not satisfy the present invention but the elongational viscosity satisfies the present invention. Note that the cross-sectional shape of the resin film is the same as in Comparative Example 2. (Example 3) As a second resin forming both ends in the resin film width direction, a first resin having an MFR of 8 g / 10 min (MFR ratio 4/5) and an elongational viscosity forming a central portion in the resin film width direction is used. A resin having an elongational viscosity of 0.9 times (elongational viscosity ratio of 0.9) was used. Then, a central portion was formed of the first resin and both end portions were extruded from the slit discharge port of the extrusion die as a resin film formed of the second resin. That is, the second resin of Example 3 is a case where the MFR satisfies the present invention but the elongational viscosity does not satisfy the present invention. Note that the cross-sectional shape of the resin film is the same as in Comparative Example 2. (Example 4) As the second resin forming both ends in the resin film width direction, the MFR was 1.0 g / 10 min (MFR ratio 1/1).
0) and a resin having an extensional viscosity of 10 times (extensional viscosity ratio 10) the extensional viscosity of the first resin forming the central portion in the resin film width direction was used. Then, a central portion was formed of the first resin, and both ends were extruded from the slit discharge port of the extrusion die as a resin film formed of the second resin. That is, the second resin of Example 4 has a significantly lower MFR and a significantly higher elongational viscosity than the first resin, and satisfies the present invention. The cross-sectional shape of the resin film is the same as that of Comparative Example 2. (Comparative Example 3) The cross-sectional shape of the resin film when the first resin and the second resin are merged is such that the first resin and the second resin are adjacent to each other as shown in FIG. Other cases are the same as in the fourth embodiment.

The above Examples 1 to 4 and Comparative Example 1
Neck-in amount on one side of the resin film for L3 (L in FIG. 2)
Also, the presence or absence of film separation between the central portion and both ends of the resin film was compared.

[0034]

[Table 1]

(Remarks) In Table 1, the value in parentheses of the MFR of the resin indicates the MFR ratio.

In Table 1, Comparative Examples 1 and 2 and Examples 1 to 4
As can be seen from the comparison with the above, either the MFR or the elongational viscosity satisfies the present invention, that is, by reducing the MFR ratio to less than 1 or increasing the elongational viscosity ratio to more than 1, the neck-in amount is reduced. We were able to.

As in the second embodiment, the second resin is MF
R does not satisfy the present invention but the elongational viscosity satisfies the present invention, or when the MFR satisfies the present invention but the elongational viscosity does not satisfy the present invention as in Example 3, ie, the MFR
The neck-in amount can be reduced even when either one of the conditions (1) and (2) is satisfied, but the effect of reducing the neck-in amount is smaller than in Examples 1 and 4 that satisfy both.

Further, even when the line speed is as high as 420 (m / min), the first resin forming the central portion in the width direction of the resin film as in the fourth embodiment and the both ends in the width direction of the resin film. When the second resin that forms the portion merges, the second resin is wrapped with the first resin, thereby preventing the first resin and the second resin from separating from each other. It was possible to maintain the effect of suppressing neck-in. In contrast, Comparative Example 3
As described above, when the first resin and the second resin are merged so as to be adjacent to each other, film separation occurs, and it is impossible to measure the neck-in amount.

The evaluation of the film shake was not described in Table 1, but the smaller the neck-in amount, the smaller the film shake. From this, it was possible to suppress the film swing by suppressing the neck-in.

In the case where the first resin and the second resin are merged adjacent to each other as shown in FIG. 3A, both ends of the extrusion die in the width direction (corresponding to both ends of the resin film in the width direction) are set. The temperature was lowered by 40 ° C. from the set temperature in the test of Table 1, and the other conditions were the same as in Example 1. As a result,
A similar neck-in effect was obtained, and no film separation occurred. That is, the temperature of the resin film at both ends is already lowered at the time when the resin film is extruded from the extrusion die, and the viscosity is increased.
As in (a), even when the first resin and the second resin are merged adjacent to each other, separation of the film could be prevented.

[0041]

As described above, according to the method for forming a resin film of the present invention, even when the manufacturing conditions such as the resin conditions and the operating conditions change, the neck-in and the accompanying films at both ends of the resin film are changed. It is possible to suppress the thickness from being increased, suppress the fluctuation of the film in which the width of the resin film fluctuates, and prevent the film from separating even if the physical properties of the resin at both ends and the center of the resin film are different.

Thus, the problem that the film thickness at both ends of the resin film increases due to the neck-in and the problem due to the film sway can be solved, and the material loss can be reduced.

Further, according to the present invention, since the speed of the line can be increased, the production efficiency can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus for manufacturing a film-like laminate to which a method for forming a resin film of the present invention is applied.

2 (a) is a front view and FIG. 2 (b) is a side view illustrating an extrusion die.

FIG. 3 is a diagram schematically showing a cross section in the width direction of a resin film extruded from an extrusion die.

[Explanation of symbols]

10: an apparatus for producing a film-like laminate, 11: resin film, 1
1A: First resin, 11B: Second resin, 12: Extrusion die, 14: Cooling roller, 16: Nip roller, 18: Peeling roller, 22: Support, 27: Film laminate, 2
8: manifold, 30: slit, 30A: slit discharge port, 32: main channel, 34: branch channel,

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Masanori Takase 200 Oozato, Fujinomiya-shi, Shizuoka Fuji Photo Film Co., Ltd. F-term (reference) 4F207 AA04 AB16 AG01 AR12 AR18 KA01 KA17 KF01 KF14 KL91 KM13

Claims (4)

[Claims] 1. A resin film forming method for forming a resin film by extruding a resin in a molten state from an extrusion die, wherein the resin forming both ends in the width direction of the resin film is located at the center in the width direction of the resin film. A method for forming a resin film, comprising using a resin having a higher extensional viscosity than a resin forming a portion. 2. A resin film forming method for forming a resin film by extruding a resin in a molten state from an extrusion die, wherein the resin forming both ends in the width direction of the resin film is located at the center in the width direction of the resin film. A method for forming a resin film, comprising using a resin having a lower MFR than a resin forming a portion. 3. A resin film forming method for forming a resin film by extruding a resin in a molten state from an extrusion die, wherein the resin forming both ends in the width direction of the resin film is located at the center in the width direction of the resin film. A method of forming a resin film, comprising using a resin having a higher elongational viscosity and a lower MFR than a resin forming a portion. 4. The resin film according to claim 1, wherein the resin forming both ends of the resin film is joined so as to be wrapped in the resin forming the central portion and extruded from the extrusion die. 2. The method for forming a resin film according to item 1.