JP7528562B2 - Manufacturing method of resin film - Google Patents

Description

The present invention relates to a resin film and a method for producing the same.

It is known that resins containing alicyclic structure-containing polymers are used as resin films for various applications. In particular, films made of materials in which a crystalline resin is used as the resin containing the alicyclic structure-containing polymer and the crystallinity of the resin is increased by a process such as heating have been proposed as films for various optical applications (for example, Patent Document 1).

International Publication No. 2016/067893

When a heating process is performed to increase the crystallinity of a resin containing an alicyclic structure-containing polymer, the thermal shrinkage rate of the resulting resin film may become undesirably high. Such a resin film with a high thermal shrinkage rate may cause undesirable phenomena such as shrinkage over time when used as a component of an optical device such as a display device.

It is generally known that a film is relaxed to reduce the thermal shrinkage. The relaxation process is usually performed by holding the film in a state where a certain degree of shrinkage is permitted, heating the film, and causing the film to shrink in a controlled manner. This process may be difficult to implement depending on the shape of the film and the production method. For example, when a long film is continuously produced, tension must be applied in the longitudinal direction of the film when the film is transported on the production line. It is relatively difficult to release this tension in the longitudinal direction in part of the production line, and it is even more difficult to control the degree of shrinkage of the film due to such release. Therefore, it is particularly difficult to reduce the thermal shrinkage in the longitudinal direction of a long film.

Therefore, the object of the present invention is to provide a long crystalline resin film with a small thermal shrinkage rate in the longitudinal direction, and a method for producing the same.

The present inventors have conducted studies to solve the above problems, and as a result, have found that when specific properties are imparted to a resin film containing an alicyclic structure-containing polymer, the reduction in the heat shrinkage rate can be achieved, and that the properties can be easily imparted to the resin film by carrying out a specific process, thereby completing the present invention.
That is, the present invention provides the following.

[1] A long resin film containing a crystalline alicyclic structure-containing polymer, the resin film having a breaking elongation of 30% or less at a temperature of 150°C and a thermal shrinkage rate in the longitudinal direction of 0.30% or less at 145°C for 1 hour.
[2] The resin film according to [1], having a crystallinity of 20% or more and 50% or less.
[3] A method for producing a resin film according to [1] or [2],
The method includes a preparation step (1) of preparing a crystallized film containing a crystalline alicyclic structure-containing polymer and having a breaking elongation of 30% or less at a temperature of 150° C.; and a heat shrinkage reduction step (2) of treating the crystallized film to reduce its heat shrinkage,
The method for producing a resin film, wherein the heat shrinkage reducing step (2) includes a stretching step (2-1) of stretching the crystallized film.
[4] The heat shrinkage reducing step (2) includes a relaxation step (2-2) of subjecting the crystallized film to a relaxation treatment after the stretching step (2-1),
The method for producing a resin film described in [3], wherein the relaxation step (2-2) includes heating the crystallized film while holding the crystallized film in a manner that allows the crystallized film to shrink in a direction parallel to the stretching direction in the stretching step (2-1).
[5] The method for producing a resin film according to [3] or [4], wherein the preparation step (1) includes a step (1-1) of preparing a raw film, and a crystallization step (1-2) of heating the raw film to thereby increase the crystallinity of the raw film to form the crystallized film.
[6] The method for producing a resin film according to any one of [3] to [5], wherein the crystallization film has a crystallinity of 10% or more.
[7] The method for producing a resin film according to any one of [3] to [6], wherein the stretching direction in the stretching step (2-1) is a width direction of the crystallized film.

The present invention provides a long crystalline resin film with a small thermal shrinkage rate in the longitudinal direction, and a method for producing the same.

The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be modified and implemented as desired without departing from the scope of the claims of the present invention and their equivalents.

In the following description, a "long" film refers to a film that is 5 times or more longer than its width, preferably 10 times or more longer, specifically a film that is long enough to be wound into a roll for storage or transportation. There is no particular upper limit to the length of the film, and it can be, for example, 100,000 times or less than its width.

In the following description, unless otherwise specified, the directions of elements being "parallel" and "orthogonal" may include an error within a range that does not impair the effect of the present invention, for example, within a range of ±3°, ±2°, or ±1°.

In the following description, the width direction is the direction perpendicular to the longitudinal direction of a long film. Usually, the longitudinal direction of a long film coincides with the film transport direction.

[1. Resin film: Overview]
The resin film of the present invention is a long resin film containing a specific polymer and has a specific breaking elongation and a specific heat shrinkage. For convenience of explanation, the resin film of the present invention may be referred to as a "product film" below to distinguish it from general resin films in general.

[1.1. Resin film material]
The product film contains a polymer containing an alicyclic structure having crystallinity. More specifically, the product film is a film formed from a thermoplastic resin containing a polymer containing an alicyclic structure having crystallinity.

The term "crystalline polymer" refers to a polymer having a melting point Tm. Whether a polymer has a melting point Tm can be confirmed using a differential scanning calorimeter (DSC).
The melting point of the crystalline polymer is not particularly limited, but is preferably 200° C. or higher, more preferably 230° C. or higher, and is preferably 290° C. or lower.
The glass transition temperature of the crystalline polymer is not particularly limited, and is, for example, 70° C. or more, 75° C. or more, or 85° C. or more, and is, for example, 170° C. or less.

An alicyclic structure-containing polymer is a polymer that has an alicyclic structure in the molecule, and refers to a polymer that can be obtained by a polymerization reaction using a cyclic olefin as a monomer, or a hydrogenated product thereof. In addition, the alicyclic structure-containing polymer may be used alone or in combination of two or more types in any ratio.

An example of a crystalline alicyclic structure-containing polymer is a norbornene-based polymer. Examples of the alicyclic structure of the alicyclic structure-containing polymer include a cycloalkane structure and a cycloalkene structure. Among these, a cycloalkane structure is preferred because it is easy to obtain a resin film with excellent properties such as thermal stability. The number of carbon atoms contained in one alicyclic structure is preferably 4 or more, more preferably 5 or more, and preferably 30 or less, more preferably 20 or less, and particularly preferably 15 or less. When the number of carbon atoms contained in one alicyclic structure is within the above range, mechanical strength, heat resistance, and moldability are highly balanced.

In the alicyclic structure-containing polymer, the ratio of the structural units having an alicyclic structure to all structural units is preferably 30% by weight or more, more preferably 50% by weight or more, and particularly preferably 70% by weight or more. By increasing the ratio of the structural units having an alicyclic structure in the alicyclic structure-containing polymer as described above, the heat resistance can be improved.
In the alicyclic structure-containing polymer, the remainder other than the structural unit having an alicyclic structure is not particularly limited and can be appropriately selected depending on the intended use.

Examples of the alicyclic structure-containing polymer include the following polymer (α) to polymer (δ). Among these, the polymer (β) is preferred as the crystalline alicyclic structure-containing polymer because it is easy to obtain a resin film having excellent heat resistance.
Polymer (α): A ring-opening polymer of a cyclic olefin monomer, which has crystallinity.
Polymer (β): A hydrogenated product of polymer (α) and has crystallinity.
Polymer (γ): An addition polymer of a cyclic olefin monomer, which has crystallinity.
Polymer (δ): A hydrogenated product of polymer (γ) or the like, which has crystallinity.

Specifically, the alicyclic structure-containing polymer is preferably a dicyclopentadiene ring-opening polymer having crystallinity, or a dicyclopentadiene ring-opening polymer hydrogenated product having crystallinity, and particularly preferably a dicyclopentadiene ring-opening polymer hydrogenated product having crystallinity. Here, the dicyclopentadiene ring-opening polymer refers to a polymer in which the ratio of dicyclopentadiene-derived structural units to all structural units is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more, and usually 100% by weight or less, and even more preferably the ratio of dicyclopentadiene-derived structural units to all structural units is 100% by weight.

The hydrogenated product of the ring-opening polymer of dicyclopentadiene preferably has a high ratio of racemo dyads. Specifically, the ratio of racemo dyads in the structural unit of the hydrogenated product of the ring-opening polymer of dicyclopentadiene is preferably 51% or more, more preferably 70% or more, and particularly preferably 85% or more. A high ratio of racemo dyads indicates high syndiotactic stereoregularity. Therefore, the higher the ratio of racemo dyads, the higher the melting point of the hydrogenated product of the ring-opening polymer of dicyclopentadiene tends to be.
The ratio of the racemo dyads can be determined based on the ¹³ C-NMR spectrum analysis described in the Examples below.

In the thermoplastic resin forming the product film, the proportion of crystalline polymer is preferably 50% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more. By making the proportion of crystalline polymer equal to or greater than the lower limit of the above range, the heat resistance of the product film can be improved.

The thermoplastic resin that forms the product film may contain optional components in addition to the crystalline polymer.

[1.2. Breaking elongation]
The product film has a breaking elongation of 30% or less at a temperature of 150°C. Specifically, the product film has a breaking elongation of 30% or less in one or more of its in-plane directions at a temperature of 150°C. More specifically, when the product film is produced by a production method including a stretching step described below, it is preferable that the breaking elongation in the direction in which the stretching step is performed is within this range. It is also preferable that the breaking elongation in the width direction of the product film is within this range.

The breaking elongation of the product film at a temperature of 150°C is preferably 25% or less, more preferably 20% or less. In this application, the breaking elongation can be measured in accordance with JIS K7161 (2014). The inventors have found that when a long resin film containing an alicyclic structure-containing polymer has such a low breaking elongation, the thermal shrinkage rate in the longitudinal direction can be easily reduced by further processing the film. A product film having such a low breaking elongation can be easily manufactured by the manufacturing method of the present invention. The manufacturing method will be described in detail later.

[1.3. Heat shrinkage rate]
The product film has a longitudinal heat shrinkage rate of 0.30% or less at 145°C for 1 hour. Such a heat shrinkage rate is preferably 0.25% or less, more preferably 0.20% or less. In general, it is difficult to achieve such a low longitudinal heat shrinkage rate for a long resin film containing a crystalline polymer, but according to the present invention, such a product film can be easily manufactured. The longitudinal heat shrinkage rate can be determined simultaneously with the transverse heat shrinkage rate by the measurement method performed in the examples described below.

[1.4. Other features of the resin film]
The dimensions of the product film can be appropriately adjusted to suit the desired application. The width direction length of the product film can be preferably in the range of 300 mm to 2000 mm. The thickness of the product film can be in the range of 10 μm to 200 μm.

The degree of crystallinity of the resin that constitutes the product film can be in an appropriate range so as to obtain the desired physical properties. Specifically, the degree of crystallinity can be in the range of 10% or more and 50% or less. The degree of crystallinity can be measured by X-ray diffraction.

2. Manufacturing method of resin film
The method for producing the resin film of the present invention is not particularly limited, but the film can be produced by a production method including the steps (1) and (2) described below. This production method will be described below as the production method of the present invention.
Step (1): A preparation step for preparing a specific crystallized film.
Step (2): A heat shrinkage reducing step of treating the crystallized film to reduce its heat shrinkage.

2.1. Step (1): Preparation of crystallized film
In the step (1), a crystallized film containing a crystalline alicyclic structure-containing polymer and having a breaking elongation of 30% or less at a temperature of 150° C. is prepared.
As a material for forming such a crystallized film, a thermoplastic resin containing a crystalline alicyclic structure-containing polymer, which is mentioned as a material for the product film, can be used.

Step (1) can be a step including a step (1-1) of preparing a raw film, and a crystallization step (1-2) of heating the raw film to increase the crystallinity of the raw film and turn it into a crystallized film. It is possible that the raw film preparation step (1-1) and the crystallization step (1-2) can be performed simultaneously (i.e., the resin can be molded into a molded product with a high degree of crystallinity), but a typical film molding process includes a step of heating and melting a thermoplastic resin to mold it, and the film obtained thereby has a low degree of crystallinity, so a manufacturing method in which steps (1-1) and (1-2) are performed in sequence can be easily implemented.

The raw film preparation step (1-1) can be carried out by molding the resin by any molding method. Examples of molding methods include injection molding, extrusion molding, press molding, inflation molding, blow molding, calendar molding, cast molding, and compression molding. Extrusion molding is preferred because it is easy to control the thickness.

The crystallization step (1-2) can be carried out by heating the original film while holding it in a state that does not allow it to shrink. By carrying out such a treatment, the crystallization degree of the original film can be increased to form a crystallized film. In addition, since the breaking elongation of a resin containing a crystalline alicyclic structure-containing polymer decreases when the crystallization degree is increased, a film whose breaking elongation meets the above requirements can be easily obtained by increasing the crystallization degree.

The crystallization step (1-2) can be performed using a stretching device for stretching a long film. Specifically, the stretching device can be a device that can stretch the film by holding both widthwise ends of the film with a number of clips and guiding and running the clips using a pair of rails arranged along the transport path at both widthwise ends of the film. The longitudinal and widthwise dimensions of the film can be changed by adjusting the arrangement of the rails and the manner in which the clips run along the rails. For example, the widthwise dimension of the film on the transport path can be changed by arranging the rails so that the spacing between the pair of rails changes from upstream to downstream. In addition, when the clips transported along the rails have a configuration mounted on a pantograph-shaped base, the longitudinal dimension of the film can also be changed. However, a stretching device that does not have such a configuration, in which clips are mounted on a chain-like base and the clips run on each rail while maintaining the intervals between the clips (i.e., the intervals between a clip and its adjacent clips upstream and between its adjacent clips downstream) without changing along the transport path, has a simple structure and allows for easier manufacturing, although it cannot freely control the change in the longitudinal dimension. In the manufacturing method of the present invention, as in the example described below, the thermal shrinkage rate in the longitudinal direction can be reduced by stretching and relaxing only in the film width direction, so in that respect it can be said to be a manufacturing method that can achieve effects that were previously difficult to achieve through simple manufacturing steps.

In the crystallization step (1-2), the heating of the original film can be achieved by adjusting the temperature around the film during transport. In the manufacturing method of the present invention, the temperature in the crystallization step (1-2) and each of the other steps can be adjusted by transporting the film in an oven. The heating temperature and heating time in the crystallization step (1-2) can be adjusted to an appropriate range that can achieve crystallization. The heating temperature can be set based on the Tg of the resin that constitutes the original film. Specifically, the heating temperature can be adjusted in the range of (Tg+30)°C or more and (Tg+100)°C or less. The heating time can be adjusted in the range of 15 seconds or more and 3 minutes or less.

The heating operation in the crystallization step (1-2) can be performed while the original film is held in a manner that does not allow the original film to shrink. Specifically, in a stretching device, the film is held by clips and conveyed while maintaining the dimensions of the film in the longitudinal and width directions unchanged, or conveyed while slightly expanding and stretching the dimensions in a certain direction. When stretching the film, it is preferable to stretch in the same direction as the stretching direction in the stretching step (2-1) (described later) in the heat shrinkage reduction treatment, and it is also preferable to stretch in the width direction. According to the inventor's findings, by stretching in such a direction, an unexpected effect of reducing the heat shrinkage rate in the longitudinal direction can be obtained. More specifically, the stretching in the crystallization step (1-2) is preferably 1.0 to 1.5 times in the width direction, more preferably 1.0 to 1.3 times in the width direction.

The heating operation in the crystallization step (1-2) may include a process (i) at a relatively low processing temperature, followed by a process (ii) at a relatively high processing temperature. In this case, when stretching the raw film, it is preferable to perform the stretching only in the process (i) stage. By performing such processes (i) and (ii) in combination, the crystallized state in the crystallized film can be better expressed. The temperature difference between the temperature of process (i) and the temperature of process (ii) is preferably 5°C or more and 30°C or less, more preferably 10°C or more and 25°C or less.

The breaking elongation of the crystallized film obtained in step (1) at a temperature of 150°C can be 30% or less. However, since the breaking elongation of the final product film can increase through subsequent steps, it is preferable to adjust the breaking elongation at this point to a lower value. Specifically, the breaking elongation is preferably 25% or less, more preferably 20% or less. Such a low breaking elongation can be easily achieved by increasing the degree of crystallization.

The crystallization degree of the crystallized film obtained in step (1) can be 10% or more, preferably 20% or more. By having such a high crystallinity, other physical properties such as breaking elongation can be set to desired values.

The crystallized film obtained in step (1) may be immediately subjected to step (2), or the crystallized film may be first collected as a film roll, and then unwound from the film roll and subjected to step (2).

[2.2. Step (2): Heat shrinkage reduction treatment]
In step (2), the crystallized film is subjected to a heat shrinkage reducing treatment. The heat shrinkage reducing step (2) includes a stretching step (2-1) of stretching the crystallized film. The heat shrinkage reducing step (2) may further include a relaxation step (2-2) of performing a relaxation treatment on the crystallized film after the stretching step (2-1).

The stretching direction in the stretching step (2-1) may be any direction capable of reducing the thermal shrinkage rate in the longitudinal direction of the product film, but is usually the width direction or a diagonal direction close to the width direction. Specifically, the angle with the width direction of the film is preferably within 10°, more preferably within 5°, and even more preferably within 1°. The stretching in the stretching step (2-1) may be stretching in two or more directions, but is typically uniaxial stretching in the width direction. The inventors have found that by stretching the crystallized film in such a direction, the unexpected effect of reducing the thermal shrinkage rate in the longitudinal direction can be obtained.

The stretching ratio in the stretching step (2-1) is preferably 1.01 times or more, more preferably 1.02 times or more, and is preferably 1.10 times or less, more preferably 1.09 times or less. By performing stretching at such a ratio, it is possible to more effectively reduce the thermal shrinkage rate in the longitudinal direction.

The temperature in the stretching step (2-1) can be adjusted to an appropriate range that can achieve the effects of the present invention. The temperature during stretching can be set based on the Tg of the resin that constitutes the original film. Specifically, the temperature during stretching can be adjusted in the range of (Tg + 60) °C or more and (Tg + 90) °C or less.

The operation in the stretching step (2-1) may include a process (iii) for expanding the dimensions of the film, followed by a process (iv) for holding the film while maintaining the expanded dimensions. By combining the processes (iii) and (iv), the reduction in the thermal shrinkage rate in the longitudinal direction can be more effectively achieved. It is preferable that the temperature difference between the process (iii) and the process (iv) is small, and more specifically, it is preferable to have the same temperature without a temperature difference from the viewpoints of both the effect and ease of processing. The processing times of the processes (iii) and (iv) can be adjusted by appropriately adjusting the arrangement of the rails in the conveying path and other conditions. The processing time of the process (iii) can be adjusted in the range of 1 second to 10 seconds. The processing time of the process (iv) can be adjusted in the range of 5 seconds to 30 seconds.

After the stretching step (2-1) is completed, the film may be used as a product film as is, or may be subjected to a relaxation step (2-2) before being used as a product film. By carrying out the relaxation step (2-2), it is possible to control the thermal shrinkage rate in the width direction as well as the thermal shrinkage rate in the longitudinal direction to a low value of 0.30% or less, which is particularly preferable.

The relaxation step (2-2) includes heating the film while holding it. The film is held in a manner that allows the film to shrink in a direction parallel to the stretching direction in the stretching step (2-1). For example, when the film is stretched in the width direction in the stretching step (2-1), the film is held in such a manner that the film can shrink in the width direction. Such holding can be performed, for example, by arranging the pair of rails of the stretching device described above so that the distance between them decreases from upstream to downstream. When such holding is performed, the film shrinks, but shrinkage at any shrinkage ratio is not allowed, but shrinkage up to a certain shrinkage ratio is allowed, and shrinkage beyond that ratio is prevented. By performing such relaxation, the film is subjected to a shrinkage treatment in a manner in which the shrinkage ratio is limited. In this case, the shrinkage ratio is preferably 0.90 times or more, more preferably 0.91 times or more, while it is preferably 0.99 times or less, more preferably 0.98 times or less. It is also preferable to adjust the product of the stretching ratio in the stretching step (2-1) and the shrinkage ratio in the relaxation step (2-2) so that these ratios are close to 1. Specifically, it is preferable for the value of this product to be in the range of 0.97 to 1.03.

The temperature in the relaxation step (2-2) can be set based on the Tg of the resin that constitutes the original film. Specifically, the temperature in the relaxation step can be adjusted in the range of (Tg + 60) ° C or more and (Tg + 90) ° C or less. It is also preferable that there is little difference in temperature between the downstream end of the stretching step (2-1) and the temperature in the relaxation step (2-2). More specifically, it is preferable to have the same temperature without any temperature difference, from the viewpoints of both effect expression and ease of processing.

The relaxation step (2-2) may be an operation including a process (v) for shrinking the dimensions of the film, followed by a process (vi) for holding the film while maintaining the shrunken dimensions. By combining the processes (v) and (vi), the reduction in the thermal shrinkage rate in the width direction can be more effectively achieved. It is preferable that the temperature difference between the process (v) and the process (vi) is small, and more specifically, it is preferable to have the same temperature without any temperature difference from the viewpoints of both the effect and ease of processing. The processing times of the processes (v) and (vi) can be adjusted by appropriately adjusting the arrangement of the rails in the conveying path and other conditions. The processing time of the process (v) can be adjusted in the range of 1 second to 10 seconds. The processing time of the process (vi) can be adjusted in the range of 5 seconds to 30 seconds.

The film obtained in step (2) can be wound up as a product film and made into a form suitable for storage and transportation, such as a film roll.

3. Uses
The uses of the resin film of the present invention are not particularly limited, but by taking advantage of the fact that it can be efficiently produced and has a small thermal shrinkage rate, it can be used as a film for a component part in optical devices such as liquid crystal display devices and organic electroluminescence display devices.

The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the examples shown below, and may be modified as desired without departing from the scope of the claims of the present invention and the scope of equivalents thereto.

In the following explanation, the percentages and parts are by weight unless otherwise specified. Furthermore, the operations described below were carried out at room temperature and pressure unless otherwise specified.

〔Evaluation methods〕
(Elongation at break)
The breaking elongation of the film was measured by the following method in accordance with JIS K7161 (2014). A test piece (IA) as specified in JIS K7161 (2014) was cut out from the film to be measured (crystallized film, product film, etc.). When cutting out the test piece, the film was cut so that the width direction of the film coincided with the longitudinal direction of the test piece.
The test piece was stretched at a test temperature of 150°C ± 1°C using a tensile tester (Instron Japan's "tensile tester with thermo-hygrostat") to measure the amount of elongation ΔL at break, and the breaking elongation was calculated from the initial length L0 and ΔL by the equation: breaking elongation (%) = ΔL/L0 × 100. When ΔL = L0, but the test piece did not break, it was considered to be over 100%.

(Thermal shrinkage rate)
The film was cut into a square of 150 mm x 150 mm in a room temperature environment of 23°C to prepare a sample film. Each side of the square was aligned along the longitudinal direction or width direction of the film. The sample film was heated in an oven at 145°C for 1 hour, cooled to 23°C (room temperature), and the lengths of the four sides of the sample film were measured.
The thermal dimensional change rate of the sample film was calculated based on the measured lengths of each of the four sides and the following formula (I): In formula (I), LA represents the length of a side of the sample film after heating.
Heat shrinkage rate (%) = [(150 - LA) / 150] x 100 (I)
Among the calculated values of the thermal dimensional change rates of the two sides along the longitudinal direction of the film, the value with the maximum absolute value was adopted as the thermal dimensional change rate in the longitudinal direction (MD) of the film, and among the calculated values of the thermal dimensional change rates of the two sides along the width direction of the film, the value with the maximum absolute value was adopted as the thermal dimensional change rate in the width direction (TD) of the film.

(Physical Properties of Polymer)
The hydrogenation rate of the polymer was measured by ¹ H-NMR measurement at 145° C. using orthodichlorobenzene- ^d4 as a solvent.
The ratio of the racemo-dyad in the polymer was determined by ¹³ C-NMR measurement. The polymer was subjected to ¹³ C-NMR measurement by applying the inverse-gated decoupling method at 200° C. using orthodichlorobenzene-d ⁴ as a solvent. From the results of this ¹³ C-NMR measurement, a signal at 43.35 ppm derived from the meso-dyad and a signal at 43.43 ppm derived from the racemo-dyad were identified, with the peak at 127.5 ppm of orthodichlorobenzene-d ⁴ being the reference shift. The ratio of the racemo-dyad in the polymer was determined based on the intensity ratio of these signals.

(Crystallization degree of crystallized film and product film)
The crystallinity of the crystallized film and the product film was measured by X-ray diffraction in accordance with JIS K 0131. Specifically, the diffracted X-ray intensity from the crystallized portion was measured using a wide-angle X-ray diffractometer (RINT 2000, manufactured by Rigaku Corporation), and the crystallinity was calculated from the ratio to the total diffracted X-ray intensity according to the following formula (I).
Xc=K・Ic/It (I)
In the above formula (I), Xc represents the crystallinity of the test sample, Ic represents the diffracted X-ray intensity from the crystallized portion, It represents the total diffracted X-ray intensity, and K represents a correction term.

[Production Example 1: Production of resin]
A metallic pressure-resistant reactor was thoroughly dried and then purged with nitrogen, and 154.5 parts of cyclohexane, 42.8 parts of a 70% cyclohexane solution of dicyclopentadiene (endo isomer content of 99% or more) (30 parts as the amount of dicyclopentadiene), and 1.9 parts of 1-hexene were added to the metallic pressure-resistant reactor, and the reactor was heated to 53°C.

0.014 parts of tetrachlorotungsten phenylimide (tetrahydrofuran) complex was dissolved in 0.70 parts of toluene to prepare a solution. 0.061 parts of a 19% diethylaluminum ethoxide/n-hexane solution was added to this solution and stirred for 10 minutes to prepare a catalyst solution. This catalyst solution was added to a pressure-resistant reactor to start the ring-opening polymerization reaction. The reaction was then continued for 4 hours while maintaining the temperature at 53°C to obtain a solution of a ring-opened polymer of dicyclopentadiene. The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the obtained ring-opened polymer of dicyclopentadiene were 8,750 and 28,100, respectively, and the molecular weight distribution (Mw/Mn) calculated from these was 3.21.

0.037 parts of 1,2-ethanediol was added as a terminator to 200 parts of the resulting solution of ring-opened dicyclopentadiene polymer, and the mixture was heated to 60°C and stirred for 1 hour to terminate the polymerization reaction. 1 part of a hydrotalcite-like compound (Kyowa Chemical Industry Co., Ltd.'s "Kyoward (registered trademark) 2000") was added to the solution, which was then heated to 60°C and stirred for 1 hour. 0.4 parts of a filter aid (Showa Chemical Industry Co., Ltd.'s "Radiolite (registered trademark) #1500") was then added, and the adsorbent and solution were filtered using a PP pleated cartridge filter (Advantec Toyo Co., Ltd.'s "TCP-HX").

100 parts of cyclohexane were added to 200 parts of the filtered ring-opening polymer solution (polymer amount 30 parts), and 0.0043 parts of chlorohydridocarbonyltris(triphenylphosphine)ruthenium was added, and a hydrogenation reaction was carried out at 6 MPa hydrogen pressure and 180°C for 4 hours. This produced a reaction liquid containing a hydrogenated product of the ring-opening polymer of dicyclopentadiene. The hydrogenated product precipitated from this reaction liquid, forming a slurry solution.

The hydrogenated product and the solution contained in the reaction liquid were separated using a centrifuge and dried under reduced pressure at 60°C for 24 hours to obtain 28.5 parts of a hydrogenated product of a crystalline ring-opening polymer of dicyclopentadiene. The hydrogenation rate of this hydrogenated product was 99% or more, the glass transition temperature Tg was 93°C, the melting point (Tm) was 262°C, and the racemo-dyad ratio was 89%.

100 parts of the obtained hydrogenated product of the ring-opening polymer of dicyclopentadiene was mixed with 1.1 parts of an antioxidant (tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane;"Irganox (registered trademark) 1010" manufactured by BASF Japan Ltd.), and the mixture was fed into a twin-screw extruder (product name "TEM-37B", manufactured by Toshiba Machine Co., Ltd.) equipped with four die holes having an inner diameter of 3 mmΦ, and molded into a strand-like product by hot melt extrusion molding. The product was then chopped with a strand cutter to obtain a hot melt extrusion molded product in the form of pellets.
The operating conditions of the twin-screw extruder are listed below.
・Barrel set temperature = 270 to 280°C ・Die set temperature = 250°C
Screw rotation speed = 145 rpm

[Production Example 2: Raw Film]
The pellet-shaped molded product obtained in Production Example 1 was molded into a raw film having a width of about 600 mm and a thickness of 40 μm using a hot melt extrusion film molding machine equipped with a T-die, and a masking film was attached to the raw film, which was then wound up into a roll. In this way, a roll of raw film was obtained. The operating conditions of the film molding machine are listed below.
・Barrel temperature setting = 280℃ to 300℃ ・Die temperature = 270℃
Screw rotation speed = 50 rpm
Cast roll temperature = 80°C
The line speed was adjusted so that the thickness of the raw film was 40 μm.

The resulting raw film was unwound from the roll, the central portion in the width direction was cut out, and the breaking elongation was measured, which was over 100%.

Example 1
(1-1. Crystallization)
The original film was pulled out from the roll of the original film obtained in Production Example 2, and the masking film was continuously peeled off, and then the original film was transported in an oven. The film was transported by holding both ends of the film in the width direction with a number of clips, and guiding the clips to run along a pair of rails arranged along the transport path at both ends of the film in the width direction. The oven used was one that was divided into multiple zones and was capable of temperature control in a state where there was a temperature difference between a certain area and another area from the upstream to the downstream of the transport path. The following processes (i) to (ii) were performed by adjusting the transport speed, the temperature of each area in the oven, and the arrangement of the rails. In the following, unless otherwise specified, the interval between the pair of rails was constant, and the film was transported without changing the dimension in the width direction. In the following, the clips on each rail were transported while maintaining the same intervals (i.e., the interval between a certain clip and its adjacent clip upstream and the interval between the clip adjacent to its adjacent clip downstream) on the transport path.

Treatment (i): The raw film was heat treated at 150° C. for 30 seconds.
Treatment (ii): Immediately after treatment (i), the film was heat-treated at 170° C. for 15 seconds to form a crystallized film.
Immediately after the end of the treatment (ii), the crystallized film was taken out of the oven. Both ends of the crystallized film were trimmed, masking films were attached, and the film was wound into a roll. The central portion of the obtained crystallized film in the width direction was cut out, and the crystallinity and the breaking elongation were measured. The crystallinity was 29%, and the breaking elongation was 18%.

(1-2. Heat shrinkage reduction treatment)
The crystallized film was pulled out from the roll obtained in (1-1), and the masking film was continuously peeled off, and then the crystallized film was transported in an oven. The film was transported by holding both ends of the film in the width direction with a number of clips, and guiding the clips with a pair of rails arranged along the transport path at both ends of the film in the width direction. The following processes (iii) to (vi) were performed by adjusting the transport speed, the temperature of each region in the oven, and the arrangement of the rails.

Treatment (iii): Immediately after the crystallized film entered the oven, the film was heat-treated at 170° C. for 5 seconds, and at the same time, the film was stretched by expanding the widthwise dimension between the start and end of treatment (iii). The widthwise dimension was expanded by arranging the rails so that the gap between the rails expanded while the film moved from upstream to downstream. The expansion ratio of the widthwise dimension was 1.05 times.
Treatment (iv): Immediately after treatment (iii), the film was heat treated at 170° C. for 15 seconds.
Treatment (v): Immediately after treatment (iv), the film was heat-treated at 170° C. for 5 seconds, and at the same time, the film was contracted in the width direction between the start and end of treatment (v). The contraction in the width direction was performed by arranging the rails so that the gap between the rails was reduced while the film moved from upstream to downstream. The contraction ratio in the width direction was 0.95 times.
Treatment (vi): Immediately after the treatment (v), the film was heat-treated at 170° C. for 15 seconds to give a product film.
Immediately after the end of the treatment (vi), the product film was removed from the oven. Both ends of the product film were trimmed, a masking film was attached, and the product film was wound into a roll. The central portion in the width direction of the obtained product film was cut out, and the thermal shrinkage ratios in the longitudinal direction and the width direction, and the breaking elongation in the longitudinal direction were measured. The thermal shrinkage ratios in the longitudinal direction and the width direction were 0.18% and -0.04%, respectively, and the breaking elongation was 25%. The crystallinity of the product film was 36%.

Example 2
Except for the following changes, the same procedure as in Example 1 was carried out to obtain and evaluate product films. The results are shown in Tables 1 to 3.
The processes (v) and (vi) were not carried out, and the film after the process (iv) was used as the product film, which was immediately removed from the oven after the process (iv).

Example 3
Except for the following changes, the same procedure as in Example 1 was carried out to obtain and evaluate product films. The results are shown in Tables 1 to 3.
In the process (i), the film was heat-treated at 150° C. for 30 seconds, and at the same time, the film was stretched by expanding the widthwise dimension between the start and end of the process (i). The expansion in the widthwise dimension was performed by arranging the rails so that the gap between the rails expanded as the film moved from upstream to downstream. The expansion ratio in the widthwise dimension was 1.2 times.

Example 4
Except for the following changes, the same procedure as in Example 1 was carried out to obtain and evaluate product films. The results are shown in Tables 1 to 3.
In the process (i), the film was heat-treated at 150° C. for 30 seconds, and at the same time, the film was stretched by expanding the widthwise dimension between the start and end of the process (i). The expansion in the widthwise dimension was performed by arranging the rails so that the gap between the rails expanded as the film moved from upstream to downstream. The expansion ratio in the widthwise dimension was 1.2 times.
The processes (v) and (vi) were not carried out, and the film after the process (iv) was used as the product film, which was immediately removed from the oven after the process (iv).

Comparative Example 1
Except for the following changes, the same procedure as in Example 1 was carried out to obtain and evaluate product films. The results are shown in Tables 1 to 3.
The crystallized film obtained in the treatment (ii) of Example 1 was used as a product film without carrying out the treatments (iii) to (vi), and the thermal shrinkage rate and the degree of crystallinity in the longitudinal and transverse directions were measured.

Comparative Example 2
Except for the following changes, the same procedure as in Example 1 was carried out to obtain and evaluate product films. The results are shown in Tables 1 to 3.
In the process (i), the film was heat-treated at 150° C. for 30 seconds, and at the same time, the film was stretched by expanding the widthwise dimension between the start and end of the process (i). The expansion in the widthwise dimension was performed by arranging the rails so that the gap between the rails expanded as the film moved from upstream to downstream. The expansion ratio in the widthwise dimension was 1.2 times.
The crystallized film obtained in the treatment (ii) of Example 1 was used as a product film without carrying out the treatments (iii) to (vi), and the thermal shrinkage rate and the degree of crystallinity in the longitudinal and transverse directions were measured.

Comparative Example 3
Except for the following changes, the same procedure as in Example 1 was carried out to obtain and evaluate product films. The results are shown in Tables 1 to 3.
The treatments (i) and (ii) were not carried out, and the raw film was pulled out from the roll of raw film obtained in Production Example 2, and this was directly subjected to treatment (iii). In addition, instead of measuring the crystallinity and breaking elongation of the crystallized film, the crystallinity and breaking elongation of the raw film were measured.
The processes (v) and (vi) were not carried out, and the film after the process (iv) was used as the product film, which was immediately removed from the oven after the process (iv).

Comparative Example 4
Except for the following changes, the same procedure as in Example 1 was carried out to obtain and evaluate product films. The results are shown in Tables 1 to 3.
The treatments (i) and (ii) were not carried out, and the raw film was pulled out from the roll of raw film obtained in Production Example 2, and this was directly subjected to treatment (iii). In addition, instead of measuring the crystallinity and breaking elongation of the crystallized film, the crystallinity and breaking elongation of the raw film were measured.

The operation overview and results of the examples and comparative examples are shown in Tables 1 to 3.

In Examples 1, 2, and Comparative Example 1, the same treatment was performed up to treatment (ii), but due to experimental error, there was some variation in the crystallinity and breaking elongation values after treatment (ii). The same was true for Examples 3, 4, and Comparative Example 2.

As is clear from the results of the Examples and Comparative Examples, in the Examples where a specific crystallized film was prepared as specified in the manufacturing method of the present invention (Manufacturing Example 1 - Process (i) - Process (ii)) and a specific stretching process (Process (iii) - (iv)) was carried out, a resin film of the present invention was obtained that had a small breaking elongation and, as a result, a small thermal shrinkage rate in the longitudinal direction. Furthermore, in the Examples where a relaxation process (Process (v) - (vi)) was carried out, a desirable product film was obtained that also had a small thermal shrinkage rate in the transverse direction.

Claims (6)

A method for producing a long resin film containing a crystalline alicyclic structure-containing polymer, the resin film having a breaking elongation of 30% or less at a temperature of 150°C and a thermal shrinkage rate in the longitudinal direction of 0.14% or more and 0.30% or less at 145°C for 1 hour ,
A preparation step (1) of preparing a crystallized film containing a crystalline alicyclic structure-containing polymer and having a breaking elongation of 30% or less at a temperature of 150° C.;
A heat shrinkage reducing step (2) of treating the crystallized film to reduce its heat shrinkage,
The method for producing a resin film, wherein the heat shrinkage reducing step (2) includes a stretching step (2-1) of stretching the crystallized film . The method for producing a resin film according to claim 1 , wherein the degree of crystallinity is from 20% to 50%. the heat shrinkage reducing step (2) includes a relaxation step (2-2) of subjecting the crystallized film to a relaxation treatment after the stretching step (2-1);
The method for producing a resin film according to claim 1 or 2, wherein the relaxation step (2-2) includes heating the crystallized film while holding the crystallized film in a manner that allows the crystallized film to shrink in a direction parallel to the stretching direction in the stretching step (2-1) . The method for producing a resin film according to any one of claims 1 to 3, wherein the preparation step (1) includes a step (1-1) of preparing a raw film, and a crystallization step (1-2) of heating the raw film to thereby increase the crystallization degree of the raw film to form the crystallized film. The method for producing a resin film according to any one of claims 1 to 4 , wherein the crystallization film has a degree of crystallization of 10% or more. The method for producing a resin film according to any one of claims 1 to 5 , wherein the stretching direction in the stretching step (2-1) is a width direction of the crystallized film.