JP2001270006A - Thermoplastic liquid crystalline polymer film and producing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic liquid crystalline polymer film, in which good evenness is equipped without damaging isotropy, and a producing method therefor. SOLUTION: Tension in the MD direction (the direction of the mechanical axis of a film) is applied to a thermoplastic liquid crystalline polymer film A. The thermoplastic liquid crystalline polymer film A is subjected to thermal shrinkage on a heating roll 2 with a recessed part 21, in which depth shown by the maximum roughness (Rmax) conforming to JIS B0601 in the temperature range from the temperature lower than its melting point by 75 deg.C to the temperature lower than the melting point by 15 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film made of a thermoplastic polymer capable of forming an optically anisotropic molten phase (hereinafter, this may be referred to as a thermoplastic liquid crystal polymer). Plastic liquid crystal polymer film) and a method for producing the same.

[0002]

2. Description of the Related Art Thermoplastic liquid crystal polymer films are:
(1) Direct heat bonding with metal foil, (2) Heat resistance, (3) Low moisture absorption, (4) Excellent thermal dimensional stability, (5) Humidity dimensional stability (6) Excellent high frequency characteristics,
(7) It is flame-retardant without containing a flame retardant such as toxic halogen, phosphorus, antimony, etc. (8) It is excellent in radiation resistance, (9) It can control thermal expansion coefficient,
(10) Due to its excellent features such as flexibility even at low temperatures, it has recently attracted attention as one of ideal materials as an electrical insulating layer material and a protective layer material for circuit boards. For this reason, there is a high demand for the realization of a circuit board using a thermoplastic liquid crystal polymer film as an electric insulating layer or a protective layer, and particularly, there is high expectation as a precision circuit board material.

[0003] The above thermoplastic liquid crystal polymer film is
It is obtained by extrusion molding of a thermoplastic liquid crystal polymer. At this time, a T-die method, an inflation method, or the like is used.
In particular, in the inflation method, not only the MD direction of the film (the mechanical axis direction of the film) but also the TD
Since stress is also applied in the direction, a film having excellent isotropy in which mechanical properties and thermal properties are balanced between the MD direction and the TD direction can be obtained.

[0004]

However, when a thermoplastic liquid crystal polymer film is produced by an inflation method, the resulting film becomes wavy and has poor flatness. Thus, conventionally, flatness has been improved by applying MD tension to the film on a heating roll and stretching the film in the MD direction. However, the polymer molecules of the thermoplastic liquid crystal polymer film are
It is a rod-like rigid molecule, and when tension is applied in the MD direction, the direction of the molecule tends to easily align with the MD direction. Therefore, merely stretching the thermoplastic liquid crystal polymer film improves the surface shape, but has the problem of deteriorating the isotropy.

Accordingly, an object of the present invention is to provide a production method capable of obtaining good flatness without impairing the isotropy of a thermoplastic liquid crystal polymer film, and a thermoplastic liquid crystal polymer film obtained by the method. Is to do.

[0006]

In order to achieve the above object, a method for producing a thermoplastic liquid crystal polymer film according to the present invention comprises the steps of:
In the temperature range from 5 ° C. lower to 15 ° C. lower than the melting point, the maximum roughness (Rma) according to JIS B0601
The depth represented by x) is in the range of 5 to 20 μm, and is brought into contact with a heating roll having a concave portion to cause thermal contraction.

The raw material of the thermoplastic liquid crystal polymer film used in the present invention is not particularly limited, but specific examples thereof include compounds classified into (1) to (4) and derivatives thereof as follows. Known thermotropic liquid crystal polyesters and thermotropic liquid crystal polyesteramides. However,
In order to obtain a polymer capable of forming an optically anisotropic molten phase, it goes without saying that there is an appropriate range for each combination of the starting compounds.

(1) Aromatic or aliphatic dihydroxy compounds (see Table 1 for typical examples)

[0009]

[Table 1]

(2) Aromatic or aliphatic dicarboxylic acids (see Table 2 for typical examples)

[0011]

[Table 2]

(3) Aromatic hydroxycarboxylic acids (see Table 3 for typical examples)

[0013]

[Table 3]

(4) Aromatic diamine, aromatic hydroxyamine or aromatic aminocarboxylic acid (see Table 4 for typical examples)

[0015]

[Table 4]

Representative examples of the thermoplastic liquid crystal polymer obtained from these starting compounds include copolymers (a) to (e) having the structural units shown in Table 5.

[0017]

[Table 5]

The thermoplastic liquid crystal polymer used in the present invention may be used in the range of about 200 to about 400 ° C., particularly about 250 to about 350 ° C. for the purpose of obtaining the desired heat resistance and processability of the film. Is preferable, but a thermoplastic liquid crystal polymer film having a relatively low melting point is easier from the viewpoint of film production. Therefore, when a higher heat resistance and a higher melting point are required, it is recommended that the obtained film be subjected to a heat treatment to increase the film to a desired heat resistance and a higher melting point. To explain an example of the condition of the heat treatment, even if the melting point of the obtained film is 283 ° C., the melting point becomes 320 ° C. after heating at 260 ° C. for 5 hours.

The thermoplastic liquid crystal polymer film used in the present invention is obtained by extruding a thermoplastic liquid crystal polymer. Although any extrusion method is used for this purpose, the well-known T-die method, inflation method, etc. are industrially advantageous. In particular, in the inflation method, since a stress is applied not only in the MD direction of the film but also in the TD direction orthogonal thereto, a film film in which the mechanical properties and the thermal properties in the MD direction and the TD direction are balanced can be obtained. Therefore, a thermoplastic liquid crystal polymer film obtained by this inflation method is more preferably used.

Preferably, the thermoplastic liquid crystal polymer film is supplied to the heating roll in a state where tension (tension) is applied in the MD direction, and is heated under the above-mentioned predetermined temperature condition and on the heating roll having a specific concave portion. Heat shrink. At this time, by selecting the concave portion of the roll, the temperature condition, and the tension, the thermoplastic liquid crystal polymer film is given good flatness without impairing the inherent isotropy.

The heating roll used in the present invention must have a large number of recesses formed on the outer peripheral surface. Here, the recess means a substantially continuous flat surface (substant
ially continuous surface plane (hereinafter referred to as a reference plane). When the depth of the recess is represented by the maximum roughness (Rmax) according to JIS B0601, this Rmax is 5
It must be set to be in the range of ２０20 μm.

The concave portion of the heating roll used may have any pattern. The depth of the concave portion provided on the heating roll is preferably as large as possible for the purpose of preventing the thermoplastic liquid crystal polymer film from slipping and improving the flatness. However, when the depth of the concave portion exceeds 20 μm, when the thermoplastic liquid crystal polymer film separates from the heating roll, there is a possibility that a part of the film which has been thermally contracted and entered the concave portion may be caught and broken. Conversely, the recess is 5
If it is smaller than μm, the thermoplastic liquid crystal polymer film and the roll may adhere to each other and may not be peeled off. As for the depth of the concave portion of the roll, Rmax is preferably in the range of 8 to 16 μm. Here, the maximum roughness is an average value obtained by measuring 20 points in the roll circumferential direction with a needle tip radius of curvature of 2 μm and a load of 20 mg using a stylus type surface roughness measuring device manufactured by Rank Taylor Bobson. .

As the heating roll, for example, a nickel-plated or chrome-plated metal roll, or a coated metal roll coated with a thin layer of a resin such as Teflon (registered trademark), silicone or polyamide is used. The surface of the heating roll is roughened by a chemical or physical method to form a number of recesses.

The heating roll is heated by a heating medium circulating therein, and the thermoplastic liquid crystal polymer film is heated by heat transmitted from the roll surface. At this time, if the surface temperature of the roll is increased and the temperature of the thermoplastic liquid crystal polymer film is increased, the flatness is improved in a short time and the productivity is increased, which is industrially convenient.
However, if the roll surface temperature is too high, a slight change in the tension applied to the film will cause breakage of the thermoplastic liquid crystal polymer film. For this reason, the thermoplastic liquid crystal polymer film becomes sufficiently soft to a temperature from 75 ° C. lower than the melting point of the thermoplastic liquid crystal polymer film to 15 ° C. from the melting point.
Temperature ranges up to lower temperatures are employed. At this time, the roll temperature is lower than the melting point of the thermoplastic liquid crystal polymer film.
If the temperature is higher than the lower temperature, the thermoplastic liquid crystal polymer film partially adheres to the surface of the roll, thereby causing deformation and significantly deteriorating the mechanical properties of the thermoplastic liquid crystal polymer film. On the other hand, when the roll temperature is lower than a temperature 75 ° C. lower than the melting point of the thermoplastic liquid crystal polymer film, the thermoplastic liquid crystal polymer film does not become soft, so that a thermoplastic liquid crystal polymer film having excellent flatness cannot be obtained.

Further, the thermoplastic liquid crystal polymer film is brought into contact with the above-mentioned heating roll in a stress-free state and is heated and contracted. This prevents the thermoplastic liquid crystal polymer film from being distorted or deformed during thermal contraction.

The melting point of the thermoplastic liquid crystal polymer film can be obtained by observing the thermal behavior of the film using a differential scanning calorimeter. In other words, the temperature of the test film is raised at a rate of 20 ° C./min to completely melt, then the melt is rapidly cooled to 50 ° C. at a rate of 50 ° C./min, and the temperature is raised again at a rate of 20 ° C./min The position of the endothermic peak that appears when this occurs is recorded as the melting point of the film.

The flatness can be improved by stretching the thermoplastic liquid crystal polymer film on the heating roll by applying a tension in the MD direction. However, specific conditions should be selected as the conditions for applying the tension. Instead, simply stretching in the MD direction causes the thermoplastic liquid crystal polymer film to lose its isotropy. If the tension is applied too much, the thermoplastic liquid crystal polymer film breaks easily, so that it is difficult to perform stable production for a long time. from these things,
In the present invention, the thermoplastic liquid crystal polymer film has 2.0
It is preferable to apply a tension of up to 3.0 kg / mm ² . At this time, if the tension is less than 2.0 kg / mm ² , the effect of improving flatness, which is the object of the present invention, tends to be insufficient. Conversely, if the tension exceeds 3.0 Kg / mm ² , a problem that impairs the isotropy of the thermoplastic liquid crystal polymer film is likely to occur, and further, the thermoplastic liquid crystal polymer film tends to break in an extreme case. It is in.

In the method of the present invention, when the thermoplastic liquid crystal polymer film passes through a heating roll maintained at a predetermined temperature condition as described above, it is necessary to effectively impart flatness to the film. The rotational speed of the roll is preferably 10 m /
Min / min, more preferably 5 m / min or less. Although there is no specific lower limit for the rotation speed, the rotation speed is preferably set to 0.5 m / min or more from the viewpoint of productivity.

Further, the thermoplastic liquid crystal polymer film obtained by the present invention has a molecular orientation degree SOR of 0.8.
It is preferably 0 to 1.30. This thermoplastic liquid crystal polymer film is more practical because it has a good balance of electrical properties, mechanical properties, and thermal properties between the MD direction and the TD direction.

Here, the degree of molecular orientation SOR (Segment Orient
The term “ation ratio” refers to an index that gives the degree of molecular orientation, and is a value that takes into account the thickness of an object, unlike conventional MOR (Molecular Orientation Ratio). This molecular orientation degree SOR is calculated as follows.

First, in a well-known microwave molecular orientation measuring instrument, a liquid crystal polymer film was inserted into a microwave resonant waveguide such that the film surface was perpendicular to the direction of microwave propagation, and was transmitted through the film. The electric field intensity (microwave transmission intensity) of the microwave is measured. Then, based on the measured value, an m value (referred to as a refractive index) is calculated by the following equation. m = (Zo / △ z) × [1-νmax / νo] where Zo is a device constant, Δz is the average thickness of the object, and νmax
Is the frequency that gives the maximum microwave transmission intensity when the frequency of the microwave is changed, and vo is the frequency that gives the maximum microwave transmission intensity when the average thickness is zero (that is, when there is no object). Next, when the rotation angle of the object with respect to the microwave oscillation direction is 0 °, that is, the direction of the microwave oscillation and the direction in which the molecules of the object are most oriented, and the minimum microwave transmission intensity is given. m ₀ to m value when the direction meets the rotation angle of the m value at 90 ° as m _90, orientation ratio SOR is calculated by m ₀ / m _90.

The thermoplastic liquid crystal polymer film obtained according to the present invention naturally has a different degree of molecular orientation SOR depending on the field of application, but when SOR ≧ 1.50, the orientation of the liquid crystal polymer molecules is significantly biased. The film becomes hard and easily tears in the MD direction. Conversely, SOR ≦ 0.
In the case of 70, it is easy to tear in the TD direction. In the case of a printed wiring board or a multilayer printed wiring board that requires dimensional stability such as no warpage during heating, 0.80 ≦ SOR ≦ 1.
Desirably, it is 30. In particular, in the case of a precision printed wiring board, a multilayer printed wiring board, or the like that requires almost no warpage during heating, it is desirable that 0.93 ≦ SOR ≦ 1.07.

The thermoplastic liquid crystal polymer film having excellent flatness obtained by the present invention has not only excellent heat resistance, chemical resistance and electrical properties derived from the thermoplastic liquid crystal polymer, but also a balance of mechanical properties. Because it has excellent bending resistance, and also has an appropriate coefficient of thermal expansion,
It is useful as a material for laminated boards such as insulating tapes, flexible printed wiring boards and multilayer thin film wiring boards. In particular, it is useful as a raw material film used as an electric insulating layer or a protective layer in a printed wiring circuit board.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the manufacturing method according to the present invention will be described below with reference to the drawings. FIG. 1 is a drawing schematically showing an example of an apparatus for producing a thermoplastic liquid crystal polymer film having excellent flatness. In FIG. 1, 1 is an unwinding roll, 2 is a heating roll, 3 is a take-up roll, and 4 is an induction roll disposed between these rolls. A thermoplastic liquid crystal polymer film A (for example, obtained in Reference Example 1 to be described later) unwound from the unwinding roll 1 is wound on a take-up roll 3 while being brought into contact with the outer peripheral surface of a rotating heating roll 2 without stress. At this time, the unwinding amount of the unwinding roll 1 was adjusted while keeping the rotation speed of the heating roll 2 constant, and
Between 2.0 and 2.0 for the thermoplastic liquid crystal polymer film A.
It is preferable to apply a tension of 3.0 kg / mm ² .
As a result, the thermoplastic liquid crystal polymer film A is in a stress-free state on the roll 2 after tension is applied between the rolls 1 and 2. The surface temperature of the heating roll 2 is:
The temperature is maintained in a temperature range from 75 ° C. lower than the melting point of the thermoplastic liquid crystal polymer film A to 15 ° C. lower than the melting point.

FIG. 2 is an enlarged sectional view of the surface of the heating roll 2. A large number of recesses 21 are formed on the surface of the heating roll 2. The recess 21 is located at the position 2 which is the most recessed from its reference plane (substantially continuous flat surface) 22.
D is up to 3 depths. This depth D is JIS B0
When expressed by the maximum roughness (Rmax) according to 601, 5
-20 μm, preferably 8-16 μm. In the concave portion 21, fine irregularities 25 may be formed as shown on the left side of FIG. Also,
As shown on the right side of the figure, a part around the recess 21 may have a protrusion 26 protruding from the reference surface 22.

[0036]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. The thickness, flatness, and appearance inspection of the thermoplastic liquid crystal polymer film described below were measured by the following methods.

(1) Film thickness Using a digital thickness gauge (manufactured by Mitutoyo Corporation), the obtained film was measured at 1 cm intervals in the TD direction, and the average value of 10 points arbitrarily selected from the center and the end was measured. The thickness was determined.

(2) Flatness and appearance inspection Each was visually observed. The flatness is evaluated as good (○) when there is no looseness or wrinkles, and the flatness is evaluated as normal (△) when there are slight wrinkles and the like, which can be commercialized.
Those that were not commercialized because wrinkles and the like remained largely were regarded as poor flatness (x).

REFERENCE EXAMPLE 1 A thermoplastic liquid crystal polymer having a melting point of 280 ° C., which is a copolymer of p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, is melt-extruded at a discharge rate of 20 kg / hour. An inflation film was formed under the conditions of 0.77 times and a longitudinal stretching ratio of 2.09 times. The average film thickness is 50 μm and the film thickness distribution is ±
A film having a molecular orientation degree SOR of 1.00 with a width of 7% and a width of 40 cm was obtained. This thermoplastic liquid crystal polymer film is designated as A.

Example 1 Using the apparatus shown in FIG. 1, the thermoplastic liquid crystal polymer film A obtained in Reference Example 1 was unwound from an unwinding roll 1, and this film A was rolled on the outer peripheral surface of a heating roll 2 for rotation. The film A was contacted in a stress-free state, and the film A was wound up by the winding roll 3 while being heated and contracted by heat under the stress-free state. At this time, the heating roll 2 has a surface with a depth of 12 mm.
A chrome-plated stainless steel plate having a diameter of 600 mm and having a large number of concave portions 21 of μm was used. The heating roll 2 was kept at a rotation speed of 3 m / min, and the surface of the roll 2 was brought into contact with the film A. A heating heater is incorporated inside the heating roll 2 to ripen the heating medium circulating inside the heating roll, and the heat causes the surface temperature of the heating roll 2 to reach 235 ° C.
Was maintained.

While changing the unwinding amount from the unwinding roll 1 to the heating roll 2, the film A
Was adjusted in various ways, and the flatness and the degree of molecular orientation SOR at this time were examined. The tension here is a tension applied to the thermoplastic liquid crystal polymer film A from the unwinding roll 1 to the heating roll 2. Table 6 shows the values of the flatness and the SOR when variously adjusting this tension.
In the table, No. 1 to No. 5 have a surface temperature of the heating roll 2 of 235 ° C., a tension (Kg / mm ² ) of 1.0,
These are the values of flatness and SOR when adjusted to 1.5, 2.0, 2.5, and 3.0.

[0042]

[Table 6]

Example 2 The flatness and the degree of molecular orientation SOR were examined in the same manner as in Example 1 except that the surface temperature of the pressure roll was changed to 240 ° C. The flatness and SOR values at this time are as shown in Table 7. In the table, No. 1 to No. 4 have a surface temperature of the heating roll 2 of 240 ° C. and a tension (Kg / mm ² ) of
These are the values of flatness and SOR when adjusted to 1.0, 1.5, 2.0, and 2.5.

[0044]

[Table 7]

Examples 3 to 5 and Comparative Examples 1 and 2 The appearance of a film obtained in the same manner as in Example 1 was examined using various pressure rolls having different depths of the concave portions. Table 8 shows the results at this time. In the table,
In Examples 3 to 5 and Comparative Examples 1 and 2, the surface temperature of the heating roll was 235 ° C., and the tension (Kg / mm ² ) was 1.0 to
This is an appearance when adjusted to a range of 3.0 Kg / mm ² .

[0046]

[Table 8]

As is clear from Tables 6 and 7 showing the results of Examples 1 and 2 above (when the heating roll temperature is 235 ° C. and 240 ° C.), the tension applied to the thermoplastic liquid crystal polymer film was 2. When it is less than 0 kg / mm ² (No. 1 in Tables 6 and 7), good flatness cannot be obtained. Although not shown in the embodiment, the tension is 3.0.
If it exceeds Kg / mm ² , the isotropic property inherent to the thermoplastic liquid crystal polymer film will be impaired. From this, the tension applied to the thermoplastic liquid crystal polymer film,
The optimal range is 2.0 kg / mm ^{2 to} 3.0 kg / mm ² . Thereby, the flatness can be improved without impairing the isotropy of the thermoplastic liquid crystal polymer film.

As is clear from Table 8 for Examples 3 to 5 and Comparative Examples 1 and 2, the depth of the concave portion was 4 μm and 3 μm.
When it is 5 μm (Examples 3 and 7), good flatness cannot be obtained, and the thermoplastic liquid crystal polymer film may be damaged. For this reason, the depth of the concave portion provided on the heating roll is in the range of 5 to 20 μm.

[0049]

As described above, according to the present invention, the flatness can be improved without impairing the isotropy of the thermoplastic liquid crystal polymer film obtained by the extrusion molding method.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing one embodiment of an apparatus for producing a thermoplastic liquid crystal polymer film having excellent flatness according to the present invention.

FIG. 2 is an enlarged sectional view of the surface of a heating roll used in the present invention.

[Explanation of symbols]

2: Heating roll, 21: recess, A: thermoplastic liquid crystal polymer film.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 7:00 B29L 7:00 C08L 67:04 C08L 67:04 F term (Reference) 4F071 AA43 AF12 AF61 BB07 BC01 4F201 AF01 AG01 AK07 AR06 AR20 BA07 BC01 BC13 BC15 BR02 BR11 4F209 AA24 AC03 AF01 AG01 AG05 AR06 PA03 PB02 PC05 PN03 PN20

Claims (3)

[Claims] 1. A film made of a thermoplastic polymer capable of forming optical anisotropy (hereinafter referred to as a thermoplastic liquid crystal polymer film) from a temperature 75 ° C. lower than its melting point to a temperature 15 ° C. lower than its melting point. In the temperature range of JI
Production of a thermoplastic liquid crystal polymer film characterized in that the film is brought into contact with a heating roll having a concave portion having a depth represented by a maximum roughness (Rmax) according to SB0601 in a range of 5 to 20 μm and thermally contracted. Method. 2. The thermoplastic liquid crystal polymer film according to claim 1, wherein said thermoplastic liquid crystal polymer film is 2.0 to 3.0 kg in the machine axis direction.
A method for producing a thermoplastic liquid crystal polymer film, wherein the thermoplastic liquid crystal polymer film is supplied to the heating roll under a tension of / mm ² . 3. The thermoplastic liquid crystal polymer film obtained according to claim 1, wherein the molecular orientation degree SOR is 0.1.
A thermoplastic liquid crystal polymer film having excellent flatness in the range of 80 to 1.30.