JP5105604B2 - Method for producing stretched film - Google Patents

Description

  The present invention relates to a method for producing a stretched film. In more detail, this invention relates to the manufacturing method of the stretched film excellent in the yield.

In the production of stretched films, improvement in economy is desired. Then, the method of extending | stretching the film formed with the propylene polymer from which an ash content differs in the width direction center part and the width direction edge part (edge part) is proposed (refer patent document 1). However, further economic improvement is desired.
JP-A-8-336884

  The present invention has been made to solve the above-described conventional problems, and a main object thereof is to provide a method for producing a stretched film that is extremely excellent in yield by selectively transversely stretching the central portion of the film. It is in.

The method for producing a stretched film of the present invention is a method for producing a stretched film having a step of transversely stretching the film, wherein the central portion in the width direction of the film is formed of the first resin composition, The part is formed of the second resin composition, and the glass transition temperature (Tg ₂ ) of the _second resin composition is higher than the glass transition temperature (Tg ₁ ) of the first resin composition.

In a preferred embodiment, the stretching temperature in the stretching step is higher than the glass transition temperature (Tg ₁ ) of the first resin composition, and is higher than the glass transition temperature (Tg ₂ ) of the second resin composition. Low.

In a preferred embodiment, the difference (Tg ₂ −Tg ₁ ) between the glass transition temperature (Tg ₂ ) of the _second resin composition and the glass transition temperature (Tg ₁ ) of the first resin composition is 5 ° C. That's it.

  In a preferred embodiment, the absolute value of the difference between the melt flow rate of the first resin composition and the melt flow rate of the second resin composition is 10 g / 10 minutes (240 ° C., 10 kgf) or less.

  In a preferred embodiment, the first resin composition includes a (meth) acrylic resin.

  In a preferred embodiment, the second resin composition contains a polycarbonate resin.

  In preferable embodiment, the width | variety of the edge part of the said film is 100 mm or less.

  According to another aspect of the present invention, a stretched film is provided. This stretched film is obtained by the above production method.

According to the present invention, it is possible to prevent the film (particularly, the end portion) from being cracked by providing the end portion formed of the resin composition having a high glass transition temperature. Moreover, a center part can be selectively extended | stretched by carrying out the horizontal stretch of the film which has the center part and edge part which were formed with the resin composition from which glass transition temperature differs. As a result, it is possible to provide a method for producing a stretched film that is extremely excellent in yield.
The stretched film obtained by the production method of the present invention can be excellent in uniformity in terms of thickness and physical properties.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment. The method for producing a stretched film of the present invention includes a step of transversely stretching the film (typically, a tenter stretching method).

A. Film FIG. 1 is a plan view showing a preferred embodiment of a film used in the method for producing a stretched film of the present invention. The film 10 has a width direction center portion 10a formed of a first resin composition, and width direction end portions 10b and 10b formed of a second resin composition. The glass transition temperature (Tg ₂ ) of the second resin composition is higher than the glass transition temperature (Tg ₁ ) of the first resin composition. For example, when a film having such a relationship is horizontally stretched by holding the end portions 10b and 10b with a clip of a tenter stretching machine, the central portion 10a formed of the first resin composition is selectively stretched. obtain. Specifically, it can be stretched to a desired thickness up to the end of the central portion 10a, and the effective width is increased (the end 10b can be cut and removed after stretching). Furthermore, the thickness unevenness of the stretched central portion 10a is small and can be excellent in uniformity. Further, by providing such end portions 10b and 10b, a stretched film having excellent physical properties and uniformity can be obtained. Specifically, in a film that does not have such an end, there may be a difference in physical properties between the vicinity of the center and the vicinity of the clip gripping part due to lateral stretching (for example, a tarmi may occur in the vicinity of the clip gripping part), By providing the end portions 10b and 10b formed of the second resin composition having a high glass transition temperature, it is possible to suppress the occurrence of a physical property difference in the central portion 10a, and the stretched film having excellent uniformity in the central portion 10a. It can be.

The difference (Tg ₂ −Tg ₁ ) between the glass transition temperature (Tg ₂ ) of the _second resin composition and the glass transition temperature (Tg ₁ ) of the first resin composition is set to any appropriate value. Can do. (Tg ₂ -Tg ₁ ) is preferably 5 ° C. or higher, more preferably 10 to 40 ° C., and particularly preferably 15 to 35 ° C. When the difference is within such a range, the central portion 10a formed of the first resin composition can be more selectively laterally stretched. Moreover, it can suppress effectively that a physical-property difference arises in the center part 10a by transverse stretching, and the stretched film excellent in uniformity can be obtained.

  The absolute value of the difference between the melt flow rate of the first resin composition and the melt flow rate of the second resin composition is preferably 10 g / 10 min (240 ° C., 10 kgf) or less, more preferably 5 g / It is 10 minutes (240 ° C., 10 kgf) or less. It is because the moldability of the film 10 can be excellent. The method for forming the film 10 will be described later.

  The first resin composition includes any appropriate resin. Specific examples of the resin include (meth) acrylic resins. In addition, when extending | stretching the film formed only from a (meth) acrylic-type resin, it exists in the tendency for a tarmi to occur easily in the clip holding part vicinity. Therefore, when the first resin composition contains a (meth) acrylic resin, the effects of the present invention can be remarkably exhibited.

Although it does not specifically limit as said (meth) acrylic-type resin, For example, poly (meth) acrylic acid ester, such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meta ) Acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), alicyclic hydrocarbon group Polymers (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth) acrylate copolymer, etc.) and the like can be mentioned. Preferably, (meth) acrylic acid C ₁ containing poly (meth) acrylate C _1-6 alkyl such as poly (meth) acrylate methyl as a main component (50 to 100% by weight, preferably 70 to 100% by weight). _-6 alkyl resin is mentioned, More preferably, the methyl methacrylate resin which has methyl methacrylate as a main component (50-100 weight%, Preferably 70-100 weight%) is mentioned.

  Specific examples of the (meth) acrylic resin include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. Examples of the resin include high Tg (meth) acrylic resins obtained by intramolecular crosslinking or intramolecular cyclization reaction. In addition, a (meth) acrylic resin having a lactone ring structure described in JP-A-2000-230016, JP-A-2001-151814, JP-A-2005-146084, and the like, and JP-A-2005-314534 are disclosed. A (meth) acrylic resin having a glutaric anhydride structure as described above may be used.

  The first resin composition may contain an optional component. Specific examples of optional components include ultraviolet absorbers, stabilizers, lubricants, processing aids, plasticizers, impact aids, phase difference reducing agents, matting agents, antibacterial agents, and fungicides.

When the (meth) acrylic resin is included, the glass transition temperature (Tg ₁ ) of the first resin composition is typically 110 ° C. or higher, preferably 115 ° C. or higher, more preferably 120 ° C. or higher. is there. It is because it can be excellent in durability. The upper limit value of Tg ₁ is typically 200 ° C. or lower, preferably 180 ° C. or lower, more preferably 160 ° C. or lower. This is because the moldability can be excellent.

  When the (meth) acrylic resin is included, the melt flow rate of the first resin composition is typically 5 to 20 g / 10 minutes (240 ° C., 10 kgf), preferably 10 to 16 g / 10 minutes. (240 ° C., 10 kgf). It is because it can be excellent in moldability and durability.

The second resin composition, as long as the glass transition temperature (Tg ₂₎ is higher than the glass transition temperature (Tg ₁₎ of the first resin composition, comprising any suitable resin. When the first resin composition includes a (meth) acrylic resin, specific examples of the resin included in the second resin composition include a polycarbonate resin. A polycarbonate resin is preferable. When the polycarbonate resin is included, the glass transition temperature (Tg ₂ ) of the second resin composition is typically 120 to 250 ° C, preferably 125 to 230 ° C, more preferably 130 to 210 ° C. . Thus, by using a polycarbonate-based resin, the preferable difference in glass transition temperature (Tg ₂ −Tg ₁ ) can be satisfied. When the polycarbonate resin is included, the melt flow rate of the second resin composition is typically 0.1 to 30 g / 10 minutes (240 ° C., 10 kgf), preferably 0.5 to 20 g / 10 minutes (240 ° C., 10 kgf). Thus, the difference of the said preferable melt flow rate can be satisfy | filled by using polycarbonate-type resin. Furthermore, the end part 10b excellent in adhesiveness with the center part 10a formed with the 1st resin composition containing a (meth) acrylic-type resin can be formed by using a polycarbonate-type resin. As a result, the film 10 can be stretched laterally. Polycarbonate resins can be obtained at a lower cost than (meth) acrylic resins, and can be economical.

  As the polycarbonate resin, an aromatic polycarbonate is preferably used. The aromatic polycarbonate can be typically obtained by a reaction between a carbonate precursor and an aromatic dihydric phenol compound. Specific examples of the carbonate precursor include phosgene, bischloroformate of dihydric phenols, diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate, di-p-chlorophenyl carbonate, dinaphthyl carbonate and the like. Can be mentioned. Among these, phosgene and diphenyl carbonate are preferable. Specific examples of the aromatic dihydric phenol compound include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, and bis (4-hydroxyphenyl). ) Methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxy-3,5-dimethylphenyl) butane, 2, 2-bis (4-hydroxy-3,5-dipropylphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethyl And cyclohexane. You may use these individually or in combination of 2 or more types. Preferably, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are Used. In particular, it is preferable to use both 2,2-bis (4-hydroxyphenyl) propane and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane.

  The second resin composition may contain an optional component. Specific examples of optional components include ultraviolet absorbers, stabilizers, lubricants, processing aids, plasticizers, impact aids, phase difference reducing agents, matting agents, antibacterial agents, and fungicides.

  The film 10 is typically a roll. The thickness of the film 10 can be set to any appropriate value. Preferably it is 10-500 micrometers, More preferably, it is 50-300 micrometers. The width | variety of the center part 10a formed with a 1st resin composition can be set to a desired value. Typically, it is 500 to 3000 mm. The width of the end portion 10b formed of the second resin composition can be set to any appropriate value as long as the end portion can be gripped by the clip of the tenter stretching machine. Preferably it is 100 mm or less, More preferably, it is 5-100 mm, Most preferably, it is 30-80 mm. Even in such a range, the central portion 10a formed of the first resin composition can be selectively laterally stretched, and a stretched film having excellent uniformity can be obtained. Moreover, it can also be excellent in economical efficiency by setting to such a value.

  As a method for forming the film 10, an extrusion method is typically used. FIG. 2 is a perspective view showing a preferred embodiment of an extrusion portion of an extruder used for the production of the film. The extrusion unit 100 includes a main extrusion unit 101 and sub-extrusion units 102 and 102. The melt of the first resin composition is extruded from the main extrusion portion 101, and the melt of the second resin composition is extruded from the sub-extrusion portions 102 and 102. The first resin composition and the second resin composition are simultaneously extruded from the die lip 110 and thinned. At this time, the first resin composition is extruded from the center portion 110a of the die lip, and the second resin composition is extruded from the end portions 110b and 110b of the die lip. In addition, the extrusion part 100 may be a form which rotated the extrusion part for obtaining a three-layer laminated film by simultaneous extrusion 90 degrees.

B. Stretching method The film is stretched transversely. For the transverse stretching, a tenter stretching method is typically used. Specifically, the end portions 10b and 10b of the film 10 are gripped by clips of a tenter stretching machine and stretched in the width direction. The stretching temperature in the stretching step is preferably higher than the glass transition temperature (Tg ₁ ) of the _first resin composition and lower than the glass transition temperature (Tg ₂ ) of the second resin composition. By setting the stretching temperature in this way, the central portion 10a formed of the first resin composition can be more selectively stretched, and a stretched film that is superior in uniformity can be obtained. Specifically, when the first resin composition contains a (meth) acrylic resin and the second resin composition contains a polycarbonate resin, it is preferably 130 to 150 ° C, more preferably 135 to 145 ° C. is there. The draw ratio can be set to any appropriate value. The draw ratio is preferably 1.1 to 5.0 times, more preferably 1.2 to 3.0 times, and particularly preferably 1.4 to 2.5 times. The film 10 can be further stretched longitudinally. In this case, sequential stretching or simultaneous biaxial stretching may be used. The draw ratio of the longitudinal drawing is preferably 1.1 to 5.0 times.

  As for the said film 10, the center part 10a formed with the 1st resin composition can be selectively laterally stretched. After stretching, by slitting the end portions 10b and 10b formed of the second resin composition, a stretched film having excellent uniformity in terms of thickness and physical properties can be obtained with high yield. The stretched film typically has a thickness of 10 to 150 μm, preferably 15 to 100 μm.

C. Use The stretched film obtained by the manufacturing method of the stretched film of this invention is used suitably as a protective film of the polarizer used for a liquid crystal display device. In addition to the protective film of the polarizer, for example, building lighting members such as windows and carport roofing materials, vehicle lighting members such as windows, agricultural lighting members such as greenhouses, lighting members, display members such as front filters, It can be used by being laminated on a housing of a home appliance, a vehicle interior member, an interior building material, wallpaper, a decorative board, an entrance door, a window frame, a baseboard, or the like.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. The glass transition temperature (Tg) and the melt flow rate were measured by the following methods.
1. Glass transition temperature (Tg)
It measured using the DSC apparatus (The Seiko Instruments company make, EXSTAR6000).
2. Melt flow rate Based on JIS-K6874, it measured with the test temperature of 240 degreeC, and the load of 10 kg.

[Example 1]
(Film forming)
An acrylic resin having a glass transition temperature of 120 ° C. (Mitsubishi Rayon, product name: Acrypet VH) is vacuum-dried at 100 ° C., and this is single-screw extruder (Toshiba Machine Co., Ltd., product name: SE-65). The raw material hopper was supplied to the main extrusion section and melted at a cylinder set temperature of 230 to 270 ° C. Note that nitrogen is substituted from the raw material hopper to the main extrusion part.
At the same time, a polycarbonate resin having a glass transition temperature of 150 ° C. (trade name Panlite L-1250Y, manufactured by Teijin Kasei Co., Ltd.) is vacuum-dried at 100 ° C., and this is single-screw extruder (manufactured by Toshiba Machine Co., Ltd., product name: The raw material hopper of SE-50) was supplied to the sub-extrusion section and melted at a cylinder set temperature of 230 to 270 ° C. Note that nitrogen is substituted from the raw material hopper to the sub-extrusion section.
As shown in FIG. 2, these were passed through a coat hanger type T-die (lip length: 500 mm, lip opening: 0.6 mm, temperature 260 ° C.) and cooled with a cooling chrome-plated casting roll at 120 ° C. Thus, the film which has the center part formed with acrylic resin and the edge part formed with polycarbonate-type resin was shape | molded. The thickness of the film thus obtained was 130 μm, the width of the central part was 1300 mm, and the width of each end part was 50 mm.

  The film obtained above was roll-stretched and longitudinally stretched, and then transversely stretched with a tenter stretching machine to obtain a stretched film. At this time, both ends formed of the polycarbonate-based resin were held with a clip and stretched laterally (stretching temperature 140 ° C., stretching ratio 1.8 times). In the obtained stretched film, the central part formed of the acrylic resin had an effective width of 1300 mm with a thickness of 40 μm ± 2.5 μm.

(Comparative Example 1)
The acrylic resin of Example 1 was formed into a film by ordinary T-die extrusion without providing an end portion formed of the polycarbonate resin. The resulting film had a thickness of 130 μm and a width of 1400 mm.
The obtained film was stretched under the same conditions as in Example 1. The effective width of the obtained stretched film having a thickness of 40 μm ± 2.5 μm was 1000 mm.

  The film thickness of the stretched film obtained in Example 1 and Comparative Example 1 was measured with a film sickness tester KG601B manufactured by Anritsu Corporation. The measurement results are shown in FIG.

  As shown in FIG. 3, the stretched film obtained in Example 1 had a substantially uniform thickness with the end portion formed of a polycarbonate-based resin as a boundary. Even if both ends of the stretched film were slit to obtain a uniform film, most of the waste pieces contained polycarbonate resin. On the other hand, the stretched film obtained in Comparative Example 1 was thicker not only in the gripping portion of the clip but also in the periphery of the gripping portion compared to the center. Therefore, in order to obtain a stretched film having a uniform thickness, it was necessary to slit the periphery of the grip portion. From the above, it can be said that the effective width is increased by providing the end portion formed of the polycarbonate resin, and the yield is remarkably improved.

  In the stretched film of Example 1 in which the thick portions at both ends were slit as described above, no sagging was observed at the slit ends. On the other hand, in the stretched film of Comparative Example 1 in which the thick portions at both ends were slit, tarmi was confirmed at the slit ends. By providing the end portion formed of the polycarbonate resin, it can be said that a stretched film excellent in uniformity in physical properties can be obtained with a high yield by suppressing the generation of tarmi.

  The stretched film of the present invention can be suitably used as an optical film such as a protective film for a polarizer.

It is a top view which shows preferable embodiment of the film used with the manufacturing method of the stretched film of this invention. It is a perspective view which shows preferable embodiment of the extrusion part of the extruder used for manufacture of the film shown in FIG. It is a graph which shows the result of the film thickness measurement of the stretched film obtained in Example 1 and Comparative Example 1 of this invention.

Explanation of symbols

10 film 10a center part 10b edge part

Claims (6)

A method for producing a stretched film having a step of transversely stretching the film,
The widthwise center of the film is formed of the first resin composition,
An end in the width direction of the film is formed of the second resin composition,
The glass transition temperature (Tg ₂ ) of the _second resin composition is higher than the glass transition temperature (Tg ₁ ) of the first resin composition,
The stretching temperature in the stretching step is higher than the glass transition temperature (Tg ₁ ) of the _first resin composition and lower than the glass transition temperature (Tg ₂ ) of the second resin composition.
A method for producing a stretched film. Wherein at the second difference between the glass transition temperature (Tg ₁₎ of the glass transition temperature of the resin composition (Tg ₂₎ and the first resin composition _(Tg 2 -Tg ₁₎ is 5 ° C. or higher, claim 2. A method for producing a stretched film according to 1.   The absolute value of the difference between the melt flow rate of the first resin composition and the melt flow rate of the second resin composition is 10 g / 10 minutes (240 ° C., 10 kgf) or less. The manufacturing method of the stretched film of description.   The manufacturing method of the stretched film in any one of Claim 1 to 3 with which the said 1st resin composition contains (meth) acrylic-type resin.   The manufacturing method of the stretched film of Claim 4 with which the said 2nd resin composition contains polycarbonate-type resin.   The manufacturing method of the stretched film in any one of Claim 1 to 5 whose width | variety of the edge part of the said film is 100 mm or less.

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