JP2009073107A - Manufacturing method of thermoplastic resin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of thermoplastic resin film capable of minimizing generation of a die line. <P>SOLUTION: The manufacturing method of thermoplastic resin film is a method of manufacturing a multilayer thermoplastic resin film by extruding two types or more of molten thermoplastic resin into a film shape by using a multi-manifold die 1. The multi-manifold die includes resin passages 18 respectively communicated with each manifold 10, and a merged passage 22 with one ends respectively communicated with ends of a side separated from the manifold 10 out of the resin passages 18, and another end communicated with a discharge opening 20 discharging the molten resin to an exterior. A ceramics membrane 22 is provided in a tip portion heading for a merging part 24 of a wall part 28 positioned between adjacent resin passages 28. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a thermoplastic resin film.

Conventionally, a plurality of manifolds, a plurality of resin flow paths communicating with the plurality of manifolds, one end communicates with an end portion of the plurality of resin flow paths away from the manifold, and the other end is melted. A multi-manifold die (so-called multi-manifold die) having a junction flow path communicating with a discharge port through which resin is discharged to the outside is known (see, for example, Patent Document 1 and Non-Patent Document 1). In a multi-manifold die, the molten resin introduced into each manifold is formed into a film shape in each manifold, and then a multilayer film is manufactured by discharging the molten resin in a film form from one discharge port. Even when the viscosity of the molten resin introduced into each manifold is different, a film having a very small thickness deviation of each layer and a very small thickness deviation of the film itself can be obtained.
JP 2004-291623 A Murakami Kenkichi, “Extrusion”, Plastics Age Co., Ltd., December 10, 1989 (7th edition revision), pp. 253-254

  However, the flow of the molten resin tends to stay at the tip portion of the wall portion located between the adjacent resin flow paths among the plurality of resin flow paths toward the merge portion between the multiple resin flow paths and the merge flow path. Therefore, the molten resin is likely to adhere to the wall surface of the tip portion and accumulate. When the molten resin adhering to the wall surface of the tip portion is solidified as it is, linear marks (so-called die lines) are formed in the multilayer film extruded from the discharge port of the multi-manifold die, and the formed film There was a problem of affecting the quality. In particular, since the tip portion is present inside the multi-manifold die, it is very difficult to remove once the molten resin adheres to the tip portion and hardens.

  Therefore, the present invention provides a method for producing a thermoplastic resin film capable of extremely suppressing the occurrence of die lines when producing a multilayer thermoplastic resin film using a multi-manifold die having a plurality of manifolds. The purpose is to provide.

  The method for producing a thermoplastic resin film according to the present invention includes a multi-layered thermoplastic resin by extruding two or more molten thermoplastic resins into a film using a multi-manifold die having a plurality of manifolds. A method for producing a film, wherein the dice communicates with a plurality of resin flow paths respectively communicating with a plurality of manifolds, and one end communicates with an end portion of the plurality of resin flow paths away from the manifold, The other end has a merging channel that communicates with a discharge port through which molten resin is discharged to the outside, and a plurality of resin streams on a wall portion located between adjacent resin channels among the plurality of resin channels A ceramic film is provided at the tip portion of the path and the merging flow path toward the merging portion.

  In the method for producing a thermoplastic resin film according to the present invention, a multi-layered thermoplastic resin film is produced using a multi-manifold die, and a resin flow channel adjacent to the die among a plurality of resin flow channels is produced. A ceramic film is provided at a tip portion of the wall portion located between the plurality of resin flow paths and the merge flow path toward the merge section. The ceramic material is a material that has a small friction with the molten resin, and the ceramic material is hard and the radius of curvature of the tip portion can be reduced, so that the molten resin is most likely to adhere to the tip portion. The presence of the ceramic film can prevent adhesion of the molten resin to the tip portion. As a result, it is possible to extremely suppress the occurrence of die lines.

  Preferably, the ceramic film has a length from the tip of the tip portion of 5 mm or more and 20 mm or less when it is assumed that the radius of curvature at the tip portion of the wall portion is 0 μm. When the radius of curvature at the tip portion of the wall is assumed to be 0 μm, when the length from the tip of the tip portion is smaller than 5 mm, the adhesion prevention effect of the molten resin by the ceramic film tends not to be sufficiently exhibited. is there. When the radius of curvature at the tip of the wall is assumed to be 0 μm and the length from the tip of the tip is greater than 20 mm, the die manufacturing cost tends to increase.

  Preferably, the radius of curvature at the tip of the wall is 50 μm or less. When the radius of curvature at the tip portion of the wall portion is larger than 50 μm, the film-like molten resin is more likely to stay in the tip portion, so that the molten resin is more likely to adhere to the wall surface of the tip portion and accumulate. There is a tendency.

  Preferably, the ceramic film is formed by thermal spraying.

  According to the present invention, when a multilayer thermoplastic resin film is manufactured using a multi-manifold die having a plurality of manifolds, a method for manufacturing a thermoplastic resin film capable of extremely suppressing the occurrence of die lines is provided. Can be provided.

  Preferred embodiments of the present invention will be described with reference to the drawings.

(Configuration of multi-manifold die)
First, the configuration of a multi-manifold die (hereinafter referred to as a multi-manifold die) 1 used in the method for producing a thermoplastic resin film according to the present invention will be described with reference to FIGS. The multi-manifold die 1 is a kind of so-called T-die and extends in a direction perpendicular to the paper surface of FIGS. 1 and 2 (for this reason, the direction perpendicular to the paper surface of FIGS. Also referred to as the width direction of the manifold die 1). The multi-manifold die 1 is made of, for example, stainless steel, die steel, carbon steel such as S45C.

  As shown in FIG. 1, the multi-manifold die 1 has a plurality (three in the present embodiment) of manifolds 10 extending in the width direction of the multi-manifold die 1. From the upper part of each manifold 10, resin flow paths 14 having a circular cross section extend toward the upper surface 12 of the multi-manifold die 1, and each resin flow path 14 is connected to an extruder (not shown). . As a combination of the connection between the resin flow path 14 and the extruder, when three extruders are connected to different resin flow paths 14, or one extruder and two resin flow paths 14 are connected. The other one extruder and the remaining resin flow path 14 are connected.

  That is, in the multi-manifold die 1, the three resin flow paths 14 and the three extruders are connected one-on-one. Therefore, the thermoplastic resin (molten resin) melted and kneaded by the extruder is supplied to each resin flow path 14. The molten resin flowing into each manifold 10 from each resin flow path 14 is spread (widened) in the width direction of the multi-manifold die 1 in each manifold 10 and formed into a film shape.

  Here, as the thermoplastic resin used for producing the thermoplastic resin film in the present embodiment, homopolymers of olefins such as ethylene, propylene, butene, hexene, and cyclic olefins, or a copolymer of two or more olefins are used. And acrylics such as polyolefin resin, polymethyl acrylate, polymethyl methacrylate, ethylene-ethyl acrylate copolymer, which are copolymers of one or more olefins and one or more polymerizable monomers polymerizable with the olefins Resin, butadiene-styrene copolymer, acrylonitrile-styrene copolymer, polystyrene, styrene resin such as styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-acrylic acid copolymer, Vinyl chloride resin Vinyl fluoride resins such as vinyl fluoride and polyvinylidene fluoride, amide resins such as 6-nylon, 6,6-nylon, 12-nylon, saturated ester resins such as polyethylene terephthalate and polyprebutylene terephthalate, polycarbonate, Polyphenylene oxide, polyacetal, polyphenylene sulfide, silicone resin, thermoplastic urethane resin, polyether ether ketone, polyether imide, polyacrylonitrile, cellulose derivative, polysulfone, polyether sulfone, various thermoplastic elastomers, or cross-linked products or modified products thereof Etc. The thermoplastic resin may be a blend of two or more different thermoplastic resins, and may contain additives as appropriate.

  Specific examples of polyolefin resins include polyethylene resins such as low density polyethylene, linear polyethylene (ethylene / α-olefin copolymer) and high density polyethylene, polypropylene, propylene / ethylene copolymer, propylene / 1. -Polypropylene resins such as butene copolymer, ethylene / cyclic olefin copolymer, ethylene / vinylcyclohexane copolymer, poly (4-methylpentene-1), poly (butene-1), ethylene / acrylic Examples include an acid methyl copolymer, an ethylene / methyl methacrylate copolymer, an ethylene / ethyl acrylate copolymer, and an ethylene / vinyl acetate copolymer.

  From the lower part of each manifold 10, resin flow paths 18 that extend in the width direction of the multi-manifold die 1 and toward the lower surface 16 side of the multi-manifold die 1 extend. The lower end of each resin flow path 18 extends in the width direction of the multi-manifold die 1 and is connected to the upper end of a merge flow path 22 that extends toward the lower surface 16 of the multi-manifold die 1. The lower end of the merging channel 22 is connected to a discharge port (lip port) 20 formed in a slit shape on the lower surface 16 of the multi-manifold die 1. In other words, one end of the merging channel 22 communicates with the end of each resin channel 18 on the side away from each manifold 10, and the other end of the merging channel 22 discharges molten resin to the outside. It communicates with the discharge port 20 that performs. In addition, the connection part of each resin flow path 18 and the merge flow path 22 becomes the merge part 24 where molten resin merges.

The inner wall surfaces of the resin flow paths 14 and 18 and the merge flow path 22 are preferably provided with a ceramic film on the entire surface. However, as shown in FIG. 1 and FIG. A ceramic film 26 is provided on the inner wall surface in the vicinity of the discharge port 20 of the flow path 22, and a ceramic film 32 is provided at a tip portion 30 of the wall portion 28 located between the adjacent resin flow paths 18 toward the junction 24. Should just be provided. As these ceramic films 26 and 32, for example, metal carbide such as tungsten carbide such as WC or W ₂ C, or metal nitride such as titanium nitride (TiN) or chromium nitride can be used.

  The average roughness Ra of the surface of the ceramic film 32 is preferably 0.2 μm or less, and preferably 0.05 μm or less. Here, the average roughness Ra is the same as the “arithmetic average roughness Ra” defined by JIS B 0601: 1994, and specifically, a non-contact type three-dimensional surface shape / roughness measuring device. A roughness curve is obtained through a phase compensation type high-pass filter with a cut-off value of 0.8 mm, and a fixed reference length is extracted from the roughness curve in the direction of the average line. The absolute value of the deviation from the average line of the part to the roughness curve is summed and averaged. As a method for reducing the average roughness Ra, for example, a method of polishing using pressure cutting using a diamond grindstone, or a method of polishing using a lapping tool (model: RT-50) manufactured by ISEL Co., Ltd. Is mentioned. When a ceramic film is provided on a part of the inner wall surfaces of the resin flow paths 14 and 18, it is preferable to polish by the above method so as not to cause a step difference in the seam between the ceramic film part and the other part. Moreover, although these ceramic films | membranes 26 and 32 can be formed by ceramic spraying, vapor deposition, etc., it is more preferable to form by ceramic spraying.

  When the ceramic film is not provided on the entire inner wall surfaces of the resin flow path 14, the resin flow path 18, and the merging flow path 22, the ceramic film is formed among the inner wall surfaces of the resin flow path 14, the resin flow path 18, and the merging flow path 22. It is only necessary that the portion not provided is plated. This plating is not particularly limited and may be hard chrome (hard chrome), copper, nickel, titanium, zinc, diamond nickel, etc., but hard chrome is more preferable because of low manufacturing cost.

  As shown in FIG. 2, the ceramic film 26 preferably has a length L1 along the wall surface of the wall portion 34 from one end to the other end of 5 mm or more and 20 mm or less. Further, the ceramic film 32 has respective lengths along the wall surface of the wall portion 28 from the tip 32 a of the tip portion 32 toward the upstream side of each resin flow path 18 in a cross section perpendicular to the width direction of the T die 12. It is preferable that the thicknesses L2 are both 5 mm or more and 20 mm or less. In these cases, if it is smaller than the lower limit, the effect of preventing adhesion of the molten resin by the ceramic films 26 and 32 tends not to be sufficiently exhibited. Further, in these cases, if it is larger than the upper limit, the manufacturing cost of the multi-manifold die 1 tends to increase.

  In addition, as shown in FIG. 2, it is preferable that the radius of curvature R <b> 1 at the discharge port 20 of the wall portion 34 constituting the merge channel 22 is 30 μm to 50 μm. Moreover, it is preferable that the curvature radius R2 in the front-end | tip part 32 of the wall part 28 is 50 micrometers or less. In these cases, if it is larger than the upper limit, the flow of the molten resin tends to stay in the discharge port 20 or the tip portion 32, and therefore the inner wall surface or the wall surface of the tip portion 32 in the vicinity of the discharge port 20 of the confluence channel 22 (particularly, There is a tendency that the molten resin adheres more easily to the wall of the tip end portion 32 formed by the ceramic film 32 and accumulates.

  Returning to FIG. 1, the multi-manifold die 1 is provided with a plurality of adjustment bolts 36 for adjusting the width of the discharge port 20 along the longitudinal direction of the multi-manifold die 1. Thereby, it becomes possible to adjust so that the thickness of the multilayer film discharged from the discharge outlet 20 may become uniform in the width direction.

(Method for producing thermoplastic resin film)
Next, a method for producing a thermoplastic resin film using the multi-manifold die 1 having the above configuration will be described.

  First, for example, different types of thermoplastic resins are put into three extruders (not shown). When the thermoplastic resin is melted and kneaded in each extruder, the molten resin reaches each manifold 10 through each resin flow path 14 and is formed into a film shape in each manifold 10. And when the molten resin shape | molded by each manifold 10 at the merge part 24 passes through each resin flow path 18 at the merge part 24, a film-form molten resin is each overlap | superposed in the merge part 24, Then, a merge flow path 22 is discharged from the discharge port 20 as a multilayer film. The multilayer film-like molten resin discharged from the discharge port 20 is cooled and solidified by a cooling roll (not shown) to obtain a multilayer thermoplastic resin film.

  In the present embodiment as described above, a multi-layer thermoplastic resin film is manufactured using the multi-manifold die 1, and the multi-manifold die 1 is provided with the ceramic film 32 at the tip portion 30 of the wall portion 28. It has been. Since the ceramic material is a material having a small friction with the molten resin, and the ceramic material is hard and the radius of curvature of the tip portion can be reduced, the molten resin is most likely to adhere to the tip portion 30 as described above. By the presence of the ceramic film 32, adhesion of the molten resin to the tip portion 30 can be prevented. As a result, it is possible to extremely suppress the occurrence of die lines.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments. For example, in the present embodiment, the multi-manifold die 1 has three manifolds 10 inside, but the present invention can be applied to any multi-manifold die having two or more manifolds inside.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on Example 1 and Comparative Example 1, this invention is not limited to a following example.

Example 1
First, a multi-manifold die 1 having the above configuration was prepared. In the multi-manifold die 1 used at this time, ceramic films 26 and 32 were formed by ceramic spraying tungsten carbide (WC). Further, the length L1 along the wall surface of the wall portion 34 was set to 15 mm, and the radius of curvature R1 at the discharge port 20 of the wall portion 34 constituting the merge channel 22 was set to 40 μm. Further, in a cross section perpendicular to the width direction of the T die 12, the length L2 along the wall surface of the wall portion 28 from the tip 32a of the tip portion 32 toward the upstream side of each resin flow path 18 is set to 10 mm. The radius of curvature R2 at the tip portion 32 of the wall portion 28 was set to 40 μm.

  Then, an ethylene-propylene copolymer (Tm (melting point) = 134 ° C., MFR (melt flow rate) = 9 g / 10 min) was introduced into the extruder A (φ65 mm), and the propylene was introduced into the extruder B (φ40 mm). -Butene copolymer (Tm = none (resin having no crystal melting peak in the range of -100 ° C to 300 ° C in differential scanning calorimetry according to JIS K 7121), MFR = 3 g / 10 min) C- (φ32 mm) was charged with an ethylene-propylene copolymer (Tm = 134 ° C., MFR = 9 g / 10 min). Thereafter, the extruders A to C are controlled such that all the resin temperatures are 230 ° C. and the layer ratio is Extruder A / Extruder B / Extruder C = 10: 10: 10. The molten resin was used to extrude, and cooled and solidified by a cooling roll whose temperature was adjusted to 25 ° C. to obtain a three-layer thermoplastic resin film.

(Comparative Example 1)
The ceramic films 26 and 32 are not present, and instead the part is covered with hard chrome, the radius of curvature R1 is set to 100 μm, and the multi-manifold die with the radius of curvature R2 set to 80 μm is used. A thermoplastic resin film of Comparative Example 1 was obtained in the same manner as Example 1.

(Evaluation results)
When the thermoplastic resin film obtained in Example 1 was observed, no die line was confirmed, and the quality was good. On the other hand, when the thermoplastic resin film obtained in Comparative Example 1 was observed, a considerable number of fine vertical stripes were confirmed between the surface and the layers.

FIG. 1 is a view showing a multi-manifold die used in the method for producing a thermoplastic resin film according to the present invention in a cross section perpendicular to the width direction of the multi-manifold die. FIG. 2 is a view showing the vicinity of the merging portion of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multi manifold die, 10 ... Manifold, 14, 18 ... Resin flow path, 20 ... Discharge port (lip port), 22 ... Merge flow path, 24 ... Merge part, 26, 32 ... Ceramic film, 28 ... Wall part, 30: The tip of the wall.

Claims (4)

Using a multi-manifold die having a plurality of manifolds, a method of producing a multilayer thermoplastic resin film by extruding two or more molten thermoplastic resins into a film,
The dice
A plurality of resin flow paths respectively communicating with the plurality of manifolds;
One end communicates with an end portion of the plurality of resin flow paths that is away from the manifold, and the other end has a merge flow path that communicates with a discharge port that discharges molten resin to the outside.
A ceramic film is provided at a tip portion of the wall portion located between adjacent resin flow paths among the plurality of resin flow paths toward the merge portion between the plurality of resin flow paths and the merge flow path. A method for producing a thermoplastic resin film.   The ceramic film has, in a cross section perpendicular to the width direction of the die, each length along the wall surface of the wall portion from the tip of the tip portion toward the upstream side of the plurality of resin flow paths. The method for producing a thermoplastic resin film according to claim 1, wherein both are 5 mm or more and 20 mm or less.   The method for producing a thermoplastic resin film according to claim 1, wherein a radius of curvature at the tip portion of the wall portion is 50 μm or less.   The method for producing a thermoplastic resin film according to any one of claims 1 to 3, wherein the ceramic film is formed by thermal spraying.

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