JP7249152B2 - Polycarbonate resin film - Google Patents

Description

The present invention relates to a polycarbonate resin film.

Films made of resins such as cycloolefin polymers are used as substrates for touch panels used in liquid crystal displays and organic EL displays. , properties such as dimensional stability at high temperatures and low birefringence are required for the above substrates.

In addition, when manufacturing liquid crystal displays and organic EL display devices that use such base materials, very strict standards are applied to their appearance, so a film (masking film) to protect the base material are used (see, for example, Patent Documents 1 and 2).

JP-A-2003-170535 Japanese Patent Application Laid-Open No. 2004-059860

Here, for example, in the manufacturing process of a transparent conductive film used for a touch panel, a heat treatment process at a high temperature (for example, 130 to 170 ° C.) is required. , this heat treatment step is performed. As the base material, polyethylene naphthalate resin, polyimide resin, polycarbonate resin, and cycloolefin polymer resin having heat resistance of 150° C. or more can be used. When using a masking film consisting of, there is a problem that the laminate of the substrate and the masking film (hereinafter simply referred to as "laminate") is deformed (large warp) in the heat treatment process.

Therefore, the present invention has been made in view of the above-mentioned problems. An object of the present invention is to provide a polycarbonate resin film that can be suppressed.

In order to achieve the above object, the polycarbonate resin film of the present invention is characterized by having a heat shrinkage rate of 0.10% or less in the longitudinal direction and the width direction after heat treatment at 140° C. for 90 minutes. .

According to the present invention, it is possible to suppress the occurrence of deformation such as warpage in the laminate in the heat treatment process.

1 is a schematic diagram showing an apparatus for manufacturing a polycarbonate resin film according to an embodiment of the invention; FIG. It is a perspective view for explaining a layered product used in curvature evaluation of an example. FIG. 4 is a schematic diagram for explaining a method of measuring a warp value in a laminate used in warp evaluation in Examples. FIG. 4 is a schematic diagram for explaining a method of measuring a warp value in a laminate used in warp evaluation in Examples.

Preferred embodiments of the present invention are described below.

<Polycarbonate resin>
The type of polycarbonate resin constituting the polycarbonate resin film of the present invention is not particularly limited, and examples thereof include thermoplastic resins obtained by reacting a dihydroxy compound with phosgene or diphenyl carbonate.

As the dihydroxy compound, for example, 2,2-bis(4-hydroxyphenyl)propane (“bisphenol A”), hydroquinone, tetramethylbisphenol A, resorcinol, and 4,4-dihydroxydiphenyl can be used. can. In addition, N-phenylphenolphthalein (melting point: 293° C.) represented by the following formula (1), bisphenol TMC (melting point: 208° C.) represented by the following formula (2), and biscresol fluorene (melting point: 208° C.) represented by the following formula (3) melting point 218-219° C.) can be used.

In addition, these can be used individually or in combination of 2 or more types.

Further examples include polycarbonate resins described in JP-A-2005-290378, JP-A-2017-19944, and International Publication No. 2011/7744.

Moreover, the method for producing the polycarbonate resin is not particularly limited, and for example, a phosgene method (interfacial polymerization method), a melt polymerization method (transesterification method), or the like can be used. In addition, a polycarbonate resin that has been subjected to a treatment for adjusting the amount of terminal OH groups may be used with respect to a polycarbonate resin raw material produced by a melt polymerization method.

Moreover, the glass transition temperature (Tg) of the polycarbonate resin is preferably 140° C. or higher and 210° C. or lower. When the Tg is 140°C or higher, the dimensional change of the masking film itself is favorable, and when the Tg of the polycarbonate resin is 210°C or less, the masking film itself is favorable in processing suitability, which is preferable.

The term "glass transition temperature" used herein refers to the midpoint glass transition temperature measured according to JIS-K-7121 (1987).

<Polycarbonate resin film>
As a method for producing the polycarbonate resin film of the present embodiment, a melt extrusion method is used, which includes a heating step of heating the polycarbonate resin that is the film-forming material, and an extrusion step of extruding the heated polycarbonate resin into a film. ing.

FIG. 1 is a schematic diagram showing an apparatus for producing a polycarbonate resin film according to this embodiment.

As shown in FIG. 1, the polycarbonate resin heated and melted in the extruder 1 is extruded from the extruder 1 in the form of a film, and after being pressed by the touch roll 2 and the cast rolls 3 and 4, a plurality of linearly arranged Slowly cool the film on the transfer roll 9 of Then, by taking off this film with take-off rolls 5, a polycarbonate resin film with little residual stress can be obtained.

For the die of the extruder 1, for example, a T die or a coat hanger die can be used.

As the touch roll 2, cast rolls 3 and 4, and take-up roll 5, metal rolls or rubber rolls can be used.

The melting temperature of the polycarbonate resin in the extruder 1 is preferably (Tg+100)° C. or higher and (Tg+200)° C. or lower in consideration of the glass transition temperature (Tg) described above. If the melting temperature is less than (Tg+100)°C, there may be an inconvenience that unmelted portions may occur. This is because it may occur.

The temperature of the cast rolls 3 and 4 is preferably (Tg-15)°C or higher and (Tg+5)°C or lower. When the temperature of the cast rolls 3 and 4 is less than (Tg-15)°C, the film may be rapidly cooled and residual stress tends to remain. , and the cast rolls 3 and 4 may be detached from the film.

In addition, the time (time until the polycarbonate resin is extruded from the outlet 1a of the extruder 1 and reaches the contact point S between the touch roll 2 and the cast roll 3) T represented by the following formula (1) is 0.26 seconds or more. It is preferably 0.65 seconds or less.

[Number 1]
Time T [seconds] = (distance E [cm] from exit 1a to contact S)/(velocity from exit 1a of polycarbonate resin to contact S [cm/s] (1)

If the time T is less than 0.26 seconds, the productivity may be lowered, and if it is longer than 0.65 seconds, residual stress in the flow direction tends to remain. This is because it may occur.

Moreover, the thickness of the polycarbonate resin film is not particularly limited, but is preferably 100 μm or more and 130 μm or less.

The polycarbonate resin film of the present embodiment is used as a masking film attached to an adherend such as a substrate for a touch panel used in an organic EL display device, or as a film used in a high-temperature treatment process such as a semiconductor molding process. be done.

Here, in the conventional masking film, as described above, when a masking film made of a material different from the material forming the base material is used, the laminate is deformed (large warp) in the heat treatment process. There was a problem.

Moreover, since the masking film is not used in the final product, it is preferable to use an inexpensive masking film.

Further, as described above, a high-temperature (for example, 130 to 170° C.) heat treatment process is required in the manufacturing process of the transparent conductive film used for the touch panel.

Therefore, the present inventors focused on this point and reduced the thermal shrinkage rate of a polycarbonate resin film, which is cheaper than the conventionally used cycloolefin polymer film, to suppress the influence of thermal shrinkage in the heat treatment process. As a result, the inventors have found a condition for suppressing the occurrence of deformation such as warpage in the laminate.

More specifically, in the polycarbonate resin film of the present invention, the thermal shrinkage after heat treatment at 140° C. for 90 minutes is measured in the mechanical axis (longitudinal) direction of the film (hereinafter referred to as “MD direction”) and , and in the (width) direction (hereinafter referred to as “TD direction”) perpendicular to this, it is 0.10% or less.

Then, by setting the heat shrinkage rate to this range, the polycarbonate resin film of the present invention is attached as a masking film to a substrate made of a material different from the polycarbonate resin (for example, cycloolefin polymer). Therefore, even when heat treatment is performed, the heat shrinkage of the polycarbonate resin film can be suppressed. Therefore, in the heat treatment step, it is possible to suppress the occurrence of deformation such as warpage in the substrate (that is, the laminate of the substrate and the polycarbonate resin film).

The term "thermal shrinkage" as used herein is the thermal shrinkage measured by the method described in Examples below.

In the polycarbonate resin film of the present invention, the absolute value of the difference between the heat shrinkage rate in the MD direction and the heat shrinkage rate in the TD direction is preferably 0.02% or less, and preferably 0.01% or less. more preferred. With such a configuration, the heat shrinkage of the polycarbonate resin becomes isotropic in the heat treatment step, so that the occurrence of deformation such as warpage in the laminate can be effectively suppressed.

Also, from the viewpoint of more effectively suppressing the occurrence of deformation such as warping in the laminate, heat shrinkage of the polycarbonate resin film and the substrate after heat treatment at 140 ° C. for 90 minutes in the MD and TD directions. The absolute value of the ratio difference is preferably 0.03% or less, more preferably 0.02% or less, and particularly preferably 0.01% or less.

More specifically, in the MD direction, when the heat shrinkage rate of the polycarbonate resin film after heat treatment at 140 ° C. for 90 minutes is H ₁ and the heat shrinkage rate of the substrate is h ₁ , the heat shrinkage rate H The absolute value of the difference between ₁ and the heat shrinkage rate h ₁ (that is, H ₁ −h ₁ ) is 0.03% or less, and the polycarbonate resin film after heat treatment at 140 ° C. for 90 minutes in the TD direction. When the heat shrinkage rate is H ₂ and the heat shrinkage rate of the substrate is h ₂ , the absolute value of the difference between the heat shrinkage rate H ₂ and the heat shrinkage rate h ₂ (that is, H ₂ −h ₂ ) is 0. 03% or less.

The present invention will be described below based on examples. In addition, the present invention is not limited to these examples, and these examples can be modified and changed based on the spirit of the present invention, and they are excluded from the scope of the present invention. isn't it.

(Example 1)
<Measurement of glass transition temperature>
The glass transition temperature of a polycarbonate resin (manufactured by Subic, trade name: Lexan HXT3143T) was measured according to JIS K7121. More specifically, a DSC curve was measured from room temperature to 200° C. at a heating rate of 5° C./min using a thermomechanical analyzer (trade name: TMA8310, manufactured by Rigaku Corporation). Then, the midpoint glass transition temperature obtained from the DSC curve measured during the second heating was taken as the glass transition temperature of the polycarbonate resin. Table 1 shows the above results.

<Method for producing polycarbonate resin film>
Next, using the apparatus shown in FIG. 1, a polycarbonate resin film was produced. More specifically, first, the pellet-shaped product of the polycarbonate resin described above is extruded at a discharge rate of 220 kg / hour from the extruder 1 set at 280 ° C., pressed by the touch roll 2 and the cast rolls 3 and 4, and then a plurality of The film was slowly cooled on the transfer roll 9 of . Then, this film was taken off by a take-off roll 5 to obtain a polycarbonate resin film having a thickness of 100 μm.

<Measurement of heat shrinkage>
Next, the heat shrinkage rate in the MD direction and the TD direction of the produced polycarbonate resin film was measured after heat treatment at 140° C. for 90 minutes. More specifically, a polycarbonate resin film sample (length: 100 mm, width: 100 mm, thickness: 100 μm) was prepared, and an automatic dimension measuring device (manufactured by Chuo Denki Keiki Mfg. Co., Ltd., trade name: GS-3025N) was used. was used to measure three distances in each of the MD and TD directions, and the average value was taken as the dimension _S0 before heat treatment in each.

Next, the sample was heated in an oven maintained at 140°C for 90 minutes, then taken out and cooled at room temperature for 30 minutes. , trade name: GS-3025N), the distances in the MD and TD directions were measured at three points each, and the average value was taken as the dimension _S1 after the heat treatment.

Then, the thermal contraction rates in the MD and TD directions were calculated using the following formula (1). Table 1 shows the above results.

[Formula 1]
Thermal shrinkage rate [%] = {(S ₀ −S ₁ )/S ₀ }×100 (1)

In addition, a sample (length: 100 mm, width: 100 mm, thickness: 40 μm) of a cycloolefin polymer film (manufactured by Nippon Zeon, trade name: Zeonor ZF-16), which is an adherend, was prepared. Similarly, the thermal contraction rates in the MD and TD directions were calculated. Table 1 shows the above results.

<Warp evaluation>
Next, the prepared polycarbonate resin film (length: 100 mm, width: 100 mm, thickness: 100 μm) was coated with an acrylic film (manufactured by Nichiei Kako, trade name: H915, length: 100 mm, width: 100 mm, Thickness: 15 μm), which is an adherend (manufactured by Nippon Zeon, trade name: Zeonor ZF-16, length: 100 mm, width: 100 mm, thickness: 40 μm). A laminate 10 in which a polycarbonate resin film 12 and a cycloolefin polymer film 13 are laminated with an adhesive layer 11 interposed therebetween was produced.

Next, this laminate 10 was heated in an oven maintained at 145° C. for 70 minutes, then taken out, placed on a smooth plate, and cooled at room temperature for 30 minutes. 2, the distance X from the surface 15a of the smooth plate 15 to the laminate 10 is measured as shown in FIGS. The maximum value of the distance X in A to D was taken as the warp value (curl value).

In addition, as shown in FIG. 3, in the laminate 10, the distance X when the polycarbonate resin film 12 side is convex toward the plate 15 side is plus (for example, when the distance X in FIG. 3 is 5 mm, +5 mm ), and as shown in FIG. 4, the distance X when the cycloolefin polymer film 13 side is convex toward the plate 15 side is set to be negative (for example, when the distance X is 5 mm in FIG. 4, -5 mm). bottom.

Then, the warpage of the laminate 10 was evaluated according to the following evaluation criteria.
-10 mm ≤ warp value ≤ +10 mm: ○
Warp value <-10 mm or 10 mm < Warp value: ×

(Examples 2-3, Comparative Examples 1-3)
A laminate 10 was produced in the same manner as in Example 1, except that at least one of the thickness of the polycarbonate resin, the heat shrinkage rate in the MD direction, and the heat shrinkage rate in the TD direction was changed to the contents shown in Table 1. and evaluated the warpage. Table 1 shows the above results.

In Examples 2 and 3 and Comparative Examples 1 and 3, the polycarbonate resin (manufactured by Subic, trade name: Lexan HXT3143T) was replaced with another polycarbonate resin (manufactured by Sumika Polycarbonate Co., Ltd., trade name: 301). -15) was used.

As shown in Table 1, in Examples 1 to 3 in which the thermal contraction rate in the MD direction and the TD direction after heat treatment at 140° C. for 90 minutes is 0.10% or less, the warp value of the laminate 10 is small, and warping in the laminate 10 can be suppressed in the heat treatment process.

As explained above, the present invention is particularly useful for polycarbonate resin films attached to adherends such as cycloolefin polymer films.

REFERENCE SIGNS LIST 1 extruder 2 nip roll 3,4 cast roll 5 take-up roll 9 transfer roll 10 laminate 11 adhesive layer 12 polycarbonate resin film 13 cycloolefin polymer film (adherend)
15 boards

Claims (3)

A polycarbonate resin film having a heat shrinkage rate of 0.10% or less in the longitudinal direction and the width direction after heat treatment at 140 ° C. for 90 minutes,
The polycarbonate resin film is attached to an adherend,
The absolute value of the difference in thermal shrinkage between the polycarbonate resin film and the adherend after heat treatment at 140° C. for 90 minutes in the longitudinal direction and the width direction is 0.03% or less. Polycarbonate resin film. 2. The polycarbonate resin film according to claim 1, wherein an absolute value of a difference between the heat shrinkage rate in the longitudinal direction and the heat shrinkage rate in the width direction is 0.02% or less. 3. The polycarbonate resin film according to claim 1, wherein the glass transition temperature of the polycarbonate resin forming the polycarbonate resin film is 140[deg.] C. or higher and 210[deg.] C. or lower.

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