JP5728183B2 - Multi-branched polyimide material, heat-resistant film, and method for producing multi-branched polyimide film - Google Patents

Description

  The present invention relates to a multibranched polyimide-based material, a heat-resistant film, and a method for producing a multibranched polyimide-based film, and is particularly used for an interlayer insulating film or a protective film of a semiconductor element, various electronic devices, solar cells, or the like. The present invention relates to a multi-branched polyimide material used for a base film or a coverlay of a flexible printed wiring board.

  In addition to being excellent in heat resistance, polyimide is also excellent in electrical insulation, chemical resistance, radiation resistance, mechanical properties, and the like, and thus has been conventionally used in various applications. In particular, in recent years, it is widely used for various electronic components. Specifically, a film-like polyimide is used as an interlayer insulating film or a protective film in a semiconductor element. In addition, polyimides having various compositions are used as constituent materials for base films or coverlays of flexible printed wiring boards employed in various electronic devices or solar cells.

  When using a polyimide film in a semiconductor element, the dimensional stability in each of the polyimide film and the semiconductor element is about the same, more specifically, the coefficient of linear thermal expansion (CTE) in each of the polyimide film and the semiconductor element. It is said that it is important to make the values comparable. This is because, for example, even when a temperature change occurs in an adherend (semiconductor element) covered with a protective film made of a polyimide film, the interface stress accompanying the temperature change of the adherend (the interface between the polyimide film and the semiconductor element) This is because the generation of stress) can be suppressed as much as possible, and cracking or peeling of the polyimide film can be prevented. For this reason, recently, development of a polyimide having a lower linear thermal expansion coefficient than before has been demanded. For example, in Patent Document 1 (International Publication No. 2005/113647), an extremely rigid molecular chain or a high molecular chain orientation is required. As a precursor capable of giving a polyesterimide having a characteristic, a polyesterimide precursor characterized by containing a repeating unit represented by a predetermined chemical formula has been proposed.

  On the other hand, for resin films including polyimide, in general, by performing stretching treatment, the molecular orientation in the resin film is controlled to control (generally reduce) the coefficient of linear expansion (CTE). Is widely known.

  For example, in Patent Document 2 (Japanese Patent Laid-Open No. 2009-67042), a solvent solution of a polyimide precursor is cast on a support, the solvent in the solvent solution is removed, and the film is peeled from the support as a self-supporting film. A method for producing a polyimide film has been proposed in which a self-supporting film is stretched in the width direction at an initial heating temperature of 80 to 300 ° C. and then heated at a final heating temperature of 350 to 580 ° C. The stretch ratio of the self-supporting film in the production method of Patent Document 2 is preferably 1.01 to 1.12 times. Here, as shown in the specification of the patent document (paragraph [0050]), the draw ratio in Patent Document 2 is A in the width direction after stretching, and the width direction before stretching. When the length is B, it is calculated from the formula: (A−B) / B. However, even in the “drawing ratio” in the following description and claims of the present application, the above It is synonymous with what is calculated from a formula.

  In Patent Document 3 (Japanese Patent Laid-Open No. 8-174659), a TAB comprising a base film layer, an adhesive layer, and a protective layer used in a TAB (Tape Automated Bonding) method which is one of IC mounting techniques. As a base film layer, a tape obtained by stretching a polyimide film at a stretch ratio of 10 to 100% in a uniaxial direction under heating has been proposed.

  In addition, Patent Document 4 (Japanese Patent No. 2999116) proposes a branched polyimide represented by a repeating unit represented by a predetermined chemical formula. In Patent Document 4, the branched polyimide is one in which a slightly multi-branched portion is introduced into a linear polyimide, and is equivalent to that at the time of melt molding such as extrusion molding as compared with a conventional linear polyimide having the same molecular weight. It is described that it exhibits a melt viscosity and an equivalent raw film can be obtained, and that further uniform stretching is possible.

  However, as far as the present inventors have investigated, in various synthetic resins that have been proposed or are currently used, the coefficient of linear thermal expansion (CTE) is in a range lower than 15 ppm / ° C. The composition of the controllable resin is limited, and many of the resins require large stretching, specifically, stretching treatment at a stretching ratio of 1 or more. The reason is that the molecular orientation generated by the stretching process with a large stretching ratio does not disappear even by the heat treatment (annealing process) after the stretching process, and the stretching effect can be maintained.

  As described above, in spite of few (limited) synthetic resin materials having excellent dimensional stability, in other words, synthetic resin materials having a low linear thermal expansion coefficient (CTE), they are particularly limited in the field of electronic devices. In the present situation where the use of synthetic resin materials is rapidly expanding, development of new synthetic resin materials having excellent mechanical properties and excellent dimensional stability is eagerly desired.

International Publication No. 2005/113647 JP 2009-67042 A JP-A-8-174659 Japanese Patent No. 2999116

  The present invention has been made in the background of such circumstances, and the problem to be solved is a multi-branched polyimide material exhibiting excellent dimensional stability as well as excellent mechanical properties, heat resistance It is providing the manufacturing method of a film and a multi-branch polyimide film.

In order to solve this problem, the present invention stretches a film composed of a multibranched polyamic acid that is an intermediate reaction product of pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene. The average coefficient of linear thermal expansion at 50 to 250 ° C. obtained by subjecting the stretching treatment to 0.05 to 0.40 times and the imidization treatment is −1.0 to 27.2 ppm / ° C. The gist of the invention is a multi-branched polyimide material made of branched polyimide. In this case, the average linear thermal expansion coefficient is measured in the same direction as the stretching direction.

In the multi-branched polyimide material according to the present invention, preferably, the draw ratio is 0.10 to 0.40 and the average linear thermal expansion coefficient is -1.0 to 10.6 ppm / ° C.

  On the other hand, this invention also makes the summary the heat resistant film which consists of the multibranched polyimide-type material of each aspect mentioned above.

Further, in the present invention, pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene are polymerized to form a film made of multibranched polyamic acid, and a film made of the multibranched polyamic acid, as the draw ratio is 0.40 times 0.05, and stretching method of the hyperbranched polyimide-based film, characterized in that to facilities imidization process also it is intended to its gist. In the method for producing such a multibranched polyimide film, the draw ratio is preferably 0.10 to 0.40.

In the multibranched polyimide material according to the present invention, the average linear thermal expansion at 50 to 250 ° C. obtained by dehydration condensation of pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene. Since it is made of a specific multi-branched polyimide having a low coefficient of -1.0 to 27.2 ppm / ° C, it can exhibit excellent dimensional stability as well as excellent mechanical properties.

Further, in the multi-branched polyimide material according to the present invention, since it is stable even after heat treatment at about 250 ° C., the specific linear thermal expansion coefficient is as low as −1.0 to 27.2 ppm / ° C. Since it consists of a branched polyimide, it can exhibit excellent dimensional stability as well as excellent mechanical properties.

In addition, the above-mentioned multibranched polyimide is particularly suitable for a film composed of a multibranched polyamic acid that is an intermediate reaction product of pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene. Is obtained by imidization by appropriately setting the stretching ratio within the above range when the film is subjected to a stretching treatment of 0.05 to 0.40 times and an imidization treatment. The average linear thermal expansion coefficient at 50 to 250 ° C. can be set to a desired value within a range of −1.0 to 27.2 ppm / ° C., and a desired multi-branched polyimide material is obtained. Can do.

  And in the heat-resistant film which consists of such a multibranched polyimide type material, it is possible to enjoy especially advantageous the mechanical characteristics and dimensional stability which material has.

It is a figure which shows the TMA curve in the thermal analysis measurement about Examples 1-4 and Comparative Example 1 of this invention. It is a graph which shows the relationship between the draw ratio in 50-250 degreeC, and an average linear thermal expansion coefficient about Examples 1-4 of this invention and Comparative Examples 1-4. It is a graph which shows the relationship between a draw ratio and a Young's modulus about Examples 1-4 of this invention, and Comparative Examples 2-4. It is a graph which shows the relationship between a draw ratio and breaking strength about Examples 1-4 of this invention, and Comparative Examples 2-4.

The multi-branched polyimide material according to the present invention is obtained by polymerizing pyromellitic anhydride (hereinafter also referred to as PMDA) and 1,3,5-tris (4-aminophenoxy) benzene (hereinafter also referred to as TAPOB). Among multi-branched polyimides, the average linear thermal expansion coefficient at 50 to 250 ° C. is relatively low at −1.0 to 27.2 ppm / ° C. The multi-branched polyimide means a polyimide having a so-called tree-like structure having many terminals in one molecule.

  About the mechanism in which the effect of this invention produces, although it is speculation, it thinks as follows. Multi-branched polyimide has a random three-dimensional structure, and its molecular structure is composed of many benzene rings and has a very rigid skeleton. When the stretching process is not performed, the multi-branched structure is substantially spherical, the degree of freedom of the molecular chain is low, and deformation does not easily occur. Here, when the stretching process is performed, in the linear structure, the polymer chain is stretched and changed into a chain state and oriented, whereas in the multi-branched structure, the substantially spherical molecule changes into an elliptical shape as a whole. , Plane orientation. Therefore, it is considered that the effect of orientation appears strongly even at a slight stretching ratio. Therefore, it is considered that multi-branched polyimide is not easily deformed with respect to the stress in the stretching direction because the orientation of the molecular chain is increased even at a slight stretching ratio, and the linear expansion coefficient is lowered, Young's modulus, and breaking strength are improved. It is done.

Moreover, the heat resistant film according to the present invention is a heat resistant film made of the above multi-branched polyimide material. Furthermore, the method for producing a multi-branched polyimide film according to the present invention comprises polymerizing pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene to form a film composed of a multi-branched polyamic acid. This is a method for producing a multi-branched polyimide film in which a film comprising a branched polyamic acid is stretched so as to have a stretching ratio of 0.05 to 0.40 times and imidized.

  The multi-branched polyimide material (heat-resistant film, ie, multi-branched polyimide film) according to the present invention can be advantageously manufactured according to the method described below.

  First, pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene are reacted to synthesize a multibranched polyamic acid.

  Here, as the pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene used in the synthesis, both commercially available products can be used as well as the multi-branch according to the present invention. It is also possible to use a material synthesized by itself for producing a polyimide material.

  In addition, the synthesis of a multi-branched polyamic acid by polymerizing pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene is relatively low temperature, specifically 100 ° C. or less, preferably 50 ° C. It is preferable to carry out under the following temperature conditions. Here, the lower limit of the temperature condition for the synthesis of the multibranched polyamic acid is preferably equal to or higher than the melting point of the solvent to be used (solvent α described later). This is because if the temperature is lower than this, the solvent freezes and hinders synthesis. For example, when N, N-dimethylacetamide (DMAc) is used as the solvent, the temperature for synthesizing the multibranched polyamic acid is preferably −20 ° C. or higher. The synthesis time (reaction time) was set so that the reaction between pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene proceeded sufficiently and the amount of both compounds used. It is determined appropriately according to

  Furthermore, the reaction between pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene is carried out by using 1,3,5-tris (4-amino) Phenoxy) benzene is preferably blended at a ratio of 0.3 to 1.2 molar equivalents. Furthermore, when 1 mol of pyromellitic anhydride is used, 1,3,5-tris (4-aminophenoxy) benzene is blended at a ratio of 0.4 to 1.1 mol equivalent, More preferably.

  In addition, the synthesis of multi-branched polyamic acid by polymerizing pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene is advantageously carried out in the following prescribed solvent (herein the solvent (with α). Examples of the solvent α used in the synthesis include N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone, dimethylformamide, dimethylsulfoxide, tetramethylsulfone, hexamethylsulfone, hexamethylphosphoamide and the like. Non-protic polar solvents, phenol solvents such as m-cresol, o-cresol, m-chlorophenol, o-chlorophenol, or ether solvents such as dioxane, tetrahydrofuran, diglyme, etc. . These solvents can be used alone or as a mixed solvent composed of two or more kinds. Further, the reaction of pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene using a solvent as described above is preferably performed in an inert gas atmosphere such as nitrogen gas or various rare gases. Implemented.

  The synthesis of hyperbranched polyamic acid by polymerizing pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene is carried out according to the above-mentioned various conditions, for example, according to the following procedure. The That is, by adding the solvent α and pyromellitic anhydride to a predetermined container at room temperature and stirring, first, pyromellitic anhydride is dissolved in the solvent α to obtain a pyromellitic anhydride solution. Next, while stirring the pyromellitic anhydride solution in a nitrogen atmosphere inside the container, 1,3,5-tris (4-aminophenoxy) benzene (TAPOB) is dissolved in a solvent α prepared separately. A multi-branched polyamic acid solution can be obtained by gradually adding the TAPOB solution to the pyromellitic anhydride solution and stirring the solution for a predetermined time.

  The polymerization of pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene is carried out so as to obtain a multibranched polyamic acid having a styrene-equivalent number average molecular weight of 5,000 to 100,000. It is more preferable to carry out so as to obtain a multibranched polyamic acid having a styrene-equivalent number average molecular weight of 10,000 to 50,000. If the number average molecular weight of the multibranched polyamic acid is too small, the film-forming property is poor and it is difficult to create a film having sufficient strength, while the number average molecular weight of the multibranched polyamic acid is too large, In the polymerization of pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene in the solvent α, a gel is formed and a homogeneous film is not formed.

Using the multi-branched polyamic acid solution synthesized as described above, the average linear thermal expansion coefficient at 50 to 250 ° C. constituting the multi-branched polyimide material of the present invention is −1.0 to 27.2 ppm / A hyperbranched polyimide at 0 ° C. is obtained. Here, the average linear thermal expansion coefficient at 50 to 250 ° C. is a thermomechanical analysis under the conditions of a tensile load of 50 mN, a temperature increase rate of 5 ° C./min, and a nitrogen atmosphere (nitrogen inflow rate is 100 mL / min). First, the temperature is once raised from room temperature (for example, 25 ° C.) to 350 ° C. at a temperature rising rate of 5 ° C./minute, cooled to room temperature (for example, 25 ° C.), and then heated again at 5 ° C./minute. Next, by subtracting the length of the test piece at 50 ° C. from the length of the test piece at 250 ° C. in the tensile direction (stretching direction) of the test piece (multi-branched polyimide film), the dimensional change is obtained and this dimension is obtained. The change is a value obtained by dividing the change by the temperature difference (200 ° C.) between the length of the test piece before tension at room temperature (for example, 25 ° C.) and the measurement temperature (JIS-K-0129: 2005). JIS-K-7197: 1991).

  In order to obtain a multi-branched polyimide having such a predetermined linear thermal expansion coefficient, the following method is advantageously employed. That is, using a multi-branched polyamic acid solution prepared according to the above-described method, first, a multi-branched polyamic acid molded body having a shape that can be subjected to a stretching treatment (uniaxial stretching treatment) is produced, and then this multi-branched polyamic acid molded body is produced. By subjecting the branched polyamic acid molded body to stretching treatment (uniaxial stretching treatment) and imidization treatment, a multi-branched polyimide constituting the multi-branched polyimide material of the present invention is obtained.

  Here, as a shape that can be subjected to stretching treatment (uniaxial stretching treatment), various shapes such as a film shape, a plate shape, and a rod shape can be adopted depending on the use of the multi-branched polyimide material. The shape is preferred.

  The production of a multi-branched polyamic acid molded article having a shape that can be subjected to a stretching treatment (uniaxial stretching treatment) is a technique according to the shape, and any technique can be used as long as it is conventionally known. It can be adopted. Specifically, as a method for producing a film-like multibranched polyamic acid molded product (multibranched polyamic acid film), a multibranched polyamide acid solution is thinly spread on a predetermined substrate and the solvent is removed to remove the multibranched polyamide. A casting method for obtaining an acid film can be exemplified.

  Next, the thus obtained multi-branched polyamic acid molded article having a form capable of being subjected to a stretching treatment (uniaxial stretching treatment) is subjected to a stretching treatment (uniaxial stretching treatment) and an imidization treatment. The

Here, the draw ratio in the drawing treatment (uniaxial drawing treatment) is preferably 0.05 to 0.40 times, more preferably 0.10 to 0.40 times, and still more preferably 0 . 20 to 0.40 times. The draw ratio of less than 0.05 times, there is a risk which can not be enjoyed effects of stretching a (lower average coefficient of linear thermal expansion) effectively in hyperbranched polyimide finally obtained, while, 0.40 This is because if the stretching treatment exceeds twice, the elongation at break of the multi-branched polyamic acid molded product is exceeded, and the film may be broken. The draw ratio in the present specification and claims means that calculated from the following formula. Since the stretching speed did not affect the stretching ratio, the stretching ratio can be determined from the length in the stretching direction as follows.
[Stretch ratio] = (X′−X) / X
However, X is the film length in the stretching direction before the stretching treatment, and X ′ is the film length in the stretching direction after the stretching treatment.

  In addition, as a technique for the stretching treatment, any conventionally known technique can be adopted as long as it is a technique capable of uniaxial stretching, and it can be carried out using various uniaxial stretching apparatuses.

  On the other hand, any imidation treatment can be adopted as long as it is a conventionally known treatment method for imidizing polyamic acid. Among such known processing methods, heat treatment (for example, 250 to 350 ° C. in a reducing atmosphere) is particularly advantageously employed.

  In the present invention, the order of carrying out the stretching treatment and the imidization treatment on the polyamic acid molded product is not particularly limited as long as a desired effect is obtained by each treatment. For example, not only when the imidization treatment is performed after the stretching treatment, but also the stretching treatment and the imidization treatment can proceed simultaneously.

And the target multibranched polyimide of this invention is obtained by performing an extending | stretching process and an imidation process with respect to a multibranched polyamic-acid molded object. The multibranched polyimide thus obtained has a relatively low average linear thermal expansion coefficient (CTE) at -250 to 250 ° C, -1.0 to 27.2 ppm / ° C. In addition to the excellent mechanical properties, excellent dimensional stability is exhibited at 50 to 250 ° C., which is higher than room temperature. The average linear thermal expansion coefficient (CTE) at 50 to 250 ° C. of the multibranched polyimide is particularly preferably −1.0 to 10.6 ppm / ° C. As a result, the multi-branched polyimide material of the present invention comprising such a multi-branched polyimide is an interlayer insulating film or protective film of a semiconductor element, or a base film such as a flexible printed wiring board used for various electronic devices or solar cells, or the like. It can be advantageously used in applications such as coverlays.

  The representative embodiment of the present invention has been described in detail above, but the present invention is not limited to the above-described embodiment. For example, even in the case of a material composed of a mixture of a multi-branched polyimide having an average linear thermal expansion coefficient within a predetermined range as described above and another resin material, the multiple according to the present invention may be used as long as the object of the present invention is not impaired. Included in the category of branched polyimide materials.

  Some examples of the present invention will be shown below to clarify the present invention more specifically. However, the present invention is not limited by the description of such examples. Needless to say. In addition to the following examples, the present invention includes various modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention, in addition to the above-described specific description. It should be understood that modifications, improvements, etc. can be made.

  In addition, about the polyimide film obtained in the following example and the comparative example, according to each following method, average linear thermal expansion coefficient (CTE), Young's modulus, breaking strength, and breaking elongation were measured or calculated, respectively.

-Average linear thermal expansion coefficient (CTE)-
Thermomechanical analysis was performed using a thermomechanical analyzer (thermal / stress / strain measuring apparatus, model name: TMA / SS6100) manufactured by SEIKO instruments. Specifically, the measurement was performed at a measurement temperature of 50 to 250 ° C. under a tensile load of 50 mN, a temperature increase rate of 5 ° C./min, and a nitrogen atmosphere (nitrogen inflow rate was 100 mL / min). First, the temperature is once raised from room temperature (for example, 25 ° C.) to 350 ° C. at a temperature rising rate of 5 ° C./minute, cooled to room temperature (for example, 25 ° C.), and then heated again at 5 ° C./minute. Next, by subtracting the length of the test piece at 50 ° C. from the length of the test piece at 250 ° C. in the tensile direction (stretching direction) of the test piece (multi-branched polyimide film), the dimensional change is obtained and this dimension is obtained. The change was divided by the length of the test piece before tension at room temperature (for example, 25 ° C.) and the temperature difference (200 ° C.) between the measured temperatures to determine the average linear thermal expansion coefficient (CTE). In this test, as a test piece (multi-branched polyimide film or linear polyimide film), a film prepared to a film thickness of 0.03 mm was appropriately stretched and then cut into a size of 30 mm × 3 mm. I did it. Therefore, the thickness of the test piece at the time of measuring the average linear thermal expansion coefficient is not necessarily the same (0.03 mm).

-Young's modulus, breaking strength and breaking elongation-
Using a tabletop tensile tester (trade name: Little Senster LSC-05 / 30) manufactured by JT Toshi Co., Ltd., test pieces of stretched polyimide film (multi-branched polyimide) in Examples and Comparative Examples (length 5 mm × A tensile test was performed at a tensile speed of 5 mm / min and room temperature (25 ° C.). At this time, the cross-sectional area of the test piece is required for calculating the stress. The thickness of the test piece before the test (before breakage) was measured at six locations, the average value was obtained, and the cross-sectional area of the test piece was calculated. The Young's modulus (GPa) was calculated from the initial gradient of the obtained stress-strain curve, and the breaking strength (MPa) and breaking elongation (%) were determined from the strength and elongation length when the film was broken. The elongation at break (%) can be obtained from the following equation.
Elongation at break (%) = [(length of specimen at break−length of specimen before test) / length of specimen before test] × 100

  The measurement conditions or calculation results of specific sample (polyimide film) production conditions, average linear thermal expansion coefficient, Young's modulus, breaking strength, and breaking elongation are shown below.

-Examples 1-4
To a 100 mL flask equipped with a stirrer, nitrogen introduction tube, calcium chloride tube and thermometer, 40 mL of N, N-dimethylacetamide (DMAc) was added and pyromellitic anhydride (PMDA): 0.65 g (3 mmol) Was dissolved. While stirring this solution under a nitrogen stream, 0.64 g (1.6 mmol) of 1,3,5-tris (4-aminophenoxy) benzene (TAPOB) dissolved in 20 mL of DMAc was gradually added. Thereafter, the mixture was further stirred at 25 ° C. for 3 hours to synthesize an acid anhydride-terminated multibranched polyamic acid. The obtained DMAc solution of acid anhydride-terminated multi-branched polyamic acid was cast on a polyester film and dried at 85 ° C. for 1 hour to obtain a semi-dried multi-branched polyamic acid film. The size of the multi-branched polyamic acid film is 80 mm × 80 mm × 0.03 mm.

  Both ends of the obtained semi-dried multi-branched polyamic acid film were fixed in parallel to a stretching jig, and 0.05 times for Example 1 was carried out based on the dimensions of the original film (length in the stretching direction). The uniaxial stretching process was performed by widening the jig interval at both ends until the stretching ratio was 0.10 times for Example 2, 0.20 times for Example 3, and 0.40 times for Example 4. . Each of the films after the uniaxial stretching treatment was subjected to a heat treatment in a nitrogen atmosphere at 100 ° C. for 1 hour, 200 ° C. for 1 hour, and further at 300 ° C. for 1 hour. ) Table 1 below shows measured values or calculation results of physical property values [average linear thermal expansion coefficient (CTE), Young's modulus, breaking strength, and breaking elongation] of each multi-branched polyimide film.

-Comparative Example 1-
About the multibranched polyamic acid film obtained by the same method as in Examples 1 to 4, heat treatment was performed under the same conditions as in Examples 1 to 4 without performing uniaxial stretching (stretching ratio is 0.00). To give a multi-branched polyimide film. The size of the multi-branched polyimide film is 80 mm × 80 mm × 0.03 mm. Table 1 below shows measured values or calculation results of physical property values [average linear thermal expansion coefficient (CTE), Young's modulus, breaking strength, and breaking elongation] of this multi-branched polyimide film.

-Comparative Examples 2-4-
To a 100 mL flask equipped with a stirrer, nitrogen introduction tube, calcium chloride tube and thermometer, 20 mL of N, N-dimethylacetamide (DMAc) was added and 4,4-oxydianiline (ODA): 0.40 g ( 2 mmol) was dissolved. While stirring this solution under a nitrogen stream, pyromellitic anhydride (PMDA): 0.44 g (2 mmol) was gradually added in a solid state, and further stirred at 25 ° C. for 3 hours to obtain linear polyamic acid. Was synthesized. The obtained DMAc solution of linear polyamic acid was cast on a polyester film and dried at 85 ° C. for 1 hour to obtain a semi-dried linear polyamic acid film. The size of the linear polyamic acid film is 80 mm × 80 mm × 0.03 mm.

  The obtained semi-dried linear polyamic acid film was fixed to a stretching jig, and 0.25 times for Comparative Example 3 and Comparative Example 4 based on the original film dimension (length in the stretching direction). A uniaxial stretching process was performed in the same manner as in Examples 1 to 4 at a stretching ratio of 0.50. In Comparative Example 2, the uniaxial stretching process was not performed (the stretching ratio was 0.00). Thereafter, each film was subjected to heat treatment at 100 ° C. for 1 hour, 200 ° C. for 1 hour, and further at 300 ° C. for 1 hour to obtain a linear polyimide film (Comparative Examples 2 to 4). . Table 1 below shows measured values or calculation results of physical property values [average linear thermal expansion coefficient (CTE), Young's modulus, breaking strength, and breaking elongation] of each linear polyimide film.

  FIG. 1 shows a TMA curve [vertical change amount (%), horizontal axis temperature (° C.)] as a result of thermal analysis measurement of each test piece of Examples 1 to 4 and Comparative Example 1. Moreover, the graph of the relationship between the draw ratio (times) in 50-250 degreeC of Examples 1-4 and Comparative Examples 1-4 and average linear thermal expansion coefficient (CTE) (ppm / degreeC) in FIG. 2 is shown.

  As is clear from the graphs of Table 1 and FIG. 2, in the polyimide films (Examples 1 to 4) made of the multi-branched polyimide material of the present invention, the draw ratio is in the draw direction (MD direction). A significant decrease in the average linear thermal expansion coefficient was observed as it increased. In particular, the polyimide film (Examples 3 and 4) having a draw ratio of 0.2 to 0.4 times has a low average linear thermal expansion coefficient, and the average linear thermal expansion coefficient is less than 0 ppm / ° C. in a specific temperature range. The peculiar property of becoming was confirmed. On the other hand, the multi-branched polyimide film having a draw ratio of 0.00 times in Comparative Example 1 has an average linear thermal expansion coefficient of 31.2 ppm / ° C., and is −1.0 to 27. It can be confirmed that it is higher than 3 ppm / ° C. Moreover, although the linear polyimide film of the comparative example 2, the comparative example 3, and the comparative example 4 showed the fall of an average linear thermal expansion coefficient as the draw ratio became large with respect to the extending | stretching direction (MD direction), an Example No significant decrease in average linear thermal expansion coefficient such as 1 to 4 was observed. As a result, it turns out that Comparative Examples 1-4 is inferior to dimensional stability compared with Examples 1-4.

  3 is a graph showing the relationship between the draw ratio (times) and Young's modulus (GPa) of Examples 1 to 4 and Comparative Examples 2 to 4, and FIG. 4 is Examples 1 to 4 and Comparative Examples 2 to 4. The graphs of the relationship between the draw ratio (times) and the breaking strength (MPa) are respectively shown.

From the graphs in Table 1 and FIGS. 3 and 4, the multi-branched polyimide films (Examples 1 to 4) show an increasing tendency with respect to the Young's modulus and the breaking strength in the stretching direction (MD direction) by the stretching treatment. It turns out that a polyimide film (Comparative Examples 1 and 2) is comparable.

Claims (5)

Stretching with a draw ratio of 0.05 to 0.40 times with respect to a film made of multi-branched polyamic acid which is an intermediate reaction product of pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene process, and are obtained by performing imidization, hyperbranched polyimide-based material consisting of hyperbranched polyimide average linear thermal expansion coefficient at 50 to 250 ° C. is a -1.0~ 27.2 ppm / ℃. The multi-branched polyimide material according to claim 1, wherein the draw ratio is 0.10 to 0.40 and the average linear thermal expansion coefficient is -1.0 to 10.6 ppm / ° C.   A heat resistant film made of the multi-branched polyimide-based material according to claim 1. Pyromellitic anhydride and 1,3,5-tris (4-aminophenoxy) benzene are polymerized to form a film made of multi-branched polyamic acid,
The film comprising the multi-branched polyamic acid is stretched so that the stretching ratio is 0.05 to 0.40 times,
Method for producing a hyperbranched polyimide-based film, characterized in that to facilities imidization process. The method for producing a multibranched polyimide film according to claim 4, wherein the draw ratio is 0.10 to 0.40.

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