JP5099577B2 - Heat resistant resin varnish, heat resistant resin film, and heat resistant resin composite - Google Patents

Description

  The present invention relates to a heat resistant resin varnish that forms a cured product that is inexpensive and excellent in toughness, a heat resistant resin film that is formed using the heat resistant resin varnish, and a heat resistant resin composite.

  Insulation coatings for insulated wires used for high-power motors for automobiles, etc., and various types of electrical equipment and flexible printed wiring boards for which miniaturization and power saving are required have recently been highly heat resistant. Along with the properties, higher elongation and strength, that is, better toughness is required.

  For example, in a high-power motor, to achieve downsizing and high efficiency (high output) with a high space factor, the coil is pressed or the number of insulated wires inserted into the stator core slot of the motor is increased. It is considered to change the cross-sectional shape of the insulated wire forming the coil from a circular shape to a hexagonal shape, a rectangular shape, etc., but in these cases, excellent toughness to prevent cracking of the insulation coating accompanying the processing There is a need for insulating materials having Further, a heat-resistant resin film used for a driving part of a mobile phone or a printer is required to have high heat resistance and mechanical properties such as excellent toughness that can withstand driving such as bending.

  A polyimide resin is known as a heat-resistant resin material having high heat resistance and excellent toughness. However, polyimide resin is expensive. Therefore, there is a demand for a high-toughness heat-resistant resin material that is inexpensive and excellent in workability.

As a heat-resistant resin material that is less expensive than polyimide resin and has excellent processability, a mixture of polyamide-imide resin and polyimide resin has been proposed. For example, JP 2005-78934 A (Patent Document 1) and This is described in Japanese Unexamined Patent Publication No. 2005-302597 (Patent Document 2).
JP 2005-78934 A JP 2005-302597 A

  However, in paragraph 0010 of Patent Document 1, “In general, it is difficult to simply mix the polyamideimide varnish and the polyamic acid (polyimide resin precursor) varnish, but the mixture is heated to 60 to 80 ° C. while mixing. , The mixture is stabilized by cooling to room temperature. ”As described in the article, when the polyamideimide resin and the polyamic acid are normally mixed, there is a problem that the coating becomes difficult due to high viscosity (gelation). Arise. In order to prevent this problem, it is necessary to provide a complicated process such as cooling and stabilizing after heating and mixing, and even if such a process is provided, mixing is often difficult in practice.

  The present invention was made in view of the above problems, and does not increase in viscosity without providing complicated steps such as heating and cooling, and is easy to apply on a substrate such as a conductor wire, It is an object of the present invention to provide a heat-resistant resin varnish that can form a cured product having excellent strength and elongation (toughness) comparable to that when a polyimide resin is used, and that is less expensive than a polyimide resin varnish. The present invention further provides a heat-resistant resin film made of a cured product of the heat-resistant resin varnish and having excellent toughness, and a heat-resistant resin composite comprising the heat-resistant resin film as a constituent element.

  As a result of intensive studies, the present inventors have been able to suppress the increase in viscosity (gelation) associated with mixing by sealing the molecular terminal isocyanate functional group of the polyamideimide resin with a blocking agent and then mixing with polyamic acid. It has been found that a low-viscosity mixture that can be applied can be obtained without heating and cooling. The inventor further found that the cured product obtained by baking the mixture thus obtained has excellent toughness close to or comparable to the polyimide resin, and completed the present invention.

  That is, this invention provides the heat resistant resin varnish characterized by containing the polyamidoimide resin which sealed the molecular terminal isocyanate functional group with the blocking agent, and polyamic acid (Claim 1).

  The polyamideimide resin that can be used here is, for example, a method in which a tricarboxylic acid anhydride and a polyvalent isocyanate having two or more isocyanate groups in one molecule are directly reacted in an organic solvent, or a polar solvent. Among them, a tricarboxylic acid anhydride and a polyvalent amine having two or more amine groups in one molecule are reacted first to introduce an imide bond first, and then two or more isocyanate groups in one molecule. It can be produced by a method such as amidation with polyvalent socyanates.

  Examples of the tricarboxylic acid anhydride include trimellitic acid anhydride (TMA), 2- (3,4-dicarboxyphenyl) -2- (3-carboxyphenyl) propane anhydride, and (3,4-dicarboxyphenyl). ) (3-carboxyphenyl) methane anhydride, (3,4-dicarboxyphenyl) (3-carboxyphenyl) ether anhydride, 3,3 ′, 4-tricarboxybenzophenone anhydride, 1,2,4-butane Tricarboxylic acid anhydride, 2,3,5-naphthalene tricarboxylic acid anhydride, 2,3,6-naphthalene tricarboxylic acid anhydride, 1,2,4-naphthalene tricarboxylic acid anhydride, 2,2 ′, 3-biphenyl tricarboxylic acid The at least 1 sort (s) chosen from an acid anhydride etc. can be mentioned. From the viewpoint of heat resistance and cost, it is preferable to use TMA.

  If necessary, a polybasic acid other than the tricarboxylic acid anhydride or a functional derivative thereof can be used in combination. Examples of polybasic acids include tribasic acids such as trimesic acid and tris (2-carboxyethyl) isocyanurate, dibasic acids such as terephthalic acid, isophthalic acid, succinic acid, adipic acid, sebacic acid and dodecanedicarboxylic acid, Aliphatic and alicyclic tetrabasic acids such as 2,3,4-butanetetracarboxylic acid, cyclopentanetetracarboxylic acid, ethylenetetracarboxylic acid, pyromellitic acid, 3,3 ′, 4,4′-benzophenone Tetracarboxylic acid, bis (3,4-dicarboxyphenyl) ether, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 2,2′-bis (3 , 4-Dicarboxyphenyl) propane, 2,2 ′, 3,3′-diphenyltetracarboxylic acid, bis (3,4-dicarboxyphenyl) sulfo It can include at least one selected from bis (3,4-carboxyphenyl) and aromatic 4-basic acid such as methane.

  Examples of the polyvalent isocyanate having two or more isocyanate groups in one molecule include aliphatic, alicyclic, araliphatic, aromatic, and heterocyclic polyisocyanates. As a more specific example, Are ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutene-1,3-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4- Diisocyanate, isophorone diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane-2,4'-diisocyanate, diph Nylmethane-4,4′-diisocyanate (MDI), diphenyl ether-4,4′-diisocyanate, xylylene diisocyanate, naphthalene-1,5-diisocyanate, 1-methoxybenzene-2,4-diisocyanate, 1-methoxybenzene-2 , 4-diisocyanate, diphenylsulfone-4,4′-diisocyanate, at least selected from compounds having three or more isocyanate groups in one molecule obtained by multiplying these diisocyanates, polyphenylmethylene polyisocyanate, and the like. One type can be mentioned.

  When a tricarboxylic acid anhydride or a functional derivative thereof, a polybasic acid used in combination as necessary or a functional derivative thereof and a polyvalent isocyanate having two or more isocyanate groups in one molecule are reacted, an organic solvent The organic solvent is preferably used in the organic solvent, and examples of the organic solvent include N-methyl-2-pyrrolidone (NM2P), N, N′-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide and the like. From the viewpoint of reactivity and the performance of the synthesized resin, it is preferable to use NM2P as a synthesis solvent.

  The polyamideimide resin can be produced, for example, by reacting TMA and MDI in an equimolar amount in an NM2P solvent. The polyamideimide resin preferably has a number average molecular weight (hereinafter, the number average molecular weight is sometimes referred to as molecular weight) of 10,000 or more. When the molecular weight is less than 10,000, the entanglement between the polyamideimide molecular chains or between the polyamideimide molecular chains and the polyimide molecular chains becomes insufficient, resulting in a decrease in toughness of the heat resistant resin film obtained by baking the heat resistant resin varnish. Tend to. Claim 2 corresponds to this preferable mode. As this polyamide-imide resin, a commercially available polyamide-imide resin varnish (for example, trade name: AE2 manufactured by Taoka Chemical Industry Co., Ltd.) can be used. Here, the number average molecular weight is a value measured by GPC in terms of polystyrene. The same applies to the following.

  Polyamic acid can be produced, for example, by reacting tetracarboxylic dianhydride and diamine at a low temperature in a polar solvent.

  Examples of tetracarboxylic dianhydrides that can be used here include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), and 3,3 ′, 4,4′-benzophenone tetracarboxylic acid. Acid dianhydride (BTDA), 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride (OPDA), 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA) ), Bicyclo (2,2,2) -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCD), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (H-PMDA), pyromellitic dianhydride (PMDA), 2,2-bis (3,4-dicarbonoxyphenyl) hexafluoropropane dianhydride (6FDA), 5- (2,5-dioxote Rahidorofuriru) methyl-3-cyclohexene-1,2-dicarboxylic anhydride (CP) can include at least one selected from the like.

Examples of diamines that can be used here include p-phenylenediamine, m-phenylenediamine, silicone diamine, bis (3-aminopropyl) etherethane, 3,3′-diamino-4,4′dihydroxydiphenylsulfone (SO ₂ —). HOAB), 4,4′diamino-3,3′dihydroxybiphenyl (HOAB), 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (HOCF ₃ AB), siloxane diamine, bis (3 -Aminopropyl) ether ethane, N, N-bis (3-aminopropyl) ether, 1,4-bis (3-aminopropyl) piperazine, isophoronediamine, 1,3'-bis (aminomethyl) cyclohexane, 3, 3'-dimethyl-4,4'-diaminodicyclohexylmethane, 4,4'-methyl Bis (cyclohexylamine), 4,4′-diaminodiphenyl ether (DDE), 3,4′-diaminodiphenyl ether (m-DDE), 3,3′-diaminodiphenyl ether, 4,4′-diamino-diphenylsulfone (p- DDS), 3,4′-diamino-diphenylsulfone, 3,3′-diamino-diphenylsulfone, 2,4′-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene (m-TPE), 1 , 3-bis (3-aminophenoxy) benzene (APB), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), 2,2-bis [4- (4-aminophenoxy) Phenyl] hexafluoropropane (HF-BAPP), bis [4- (4-aminophenoxy) phenyl] sulfur (P-BAPS), bis [4- (3-aminophenoxy) phenyl] sulfone (m-BAPS), 4,4′bis (4-aminophenoxy) biphenyl (BAPB), 1,4-bis (4- Aminophenoxy) benzene (p-TPE), 4,4′-diaminodiphenyl sulfide (ASD), 3,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfide, 3,3′diamino-4,4 ′ Dihydroxydiphenylsulfone, 2,4-diaminotoluene (DAT), 2,5-diaminotoluene, 3,5-diaminobenzoic acid (DABz), 2,6-diaminopyridine (DAPy), 4,4′diamino-3, 3 'dimethoxy-biphenyl _(CH 3 OAB), 4, 4'diamino-3,3'-dimethyl biphenyl _(CH 3 AB), 9,9'-bis ( - it can include at least one selected from aminophenyl) fluorene (FDA) and the like.

  When reacting tetracarboxylic dianhydride and diamine, it is preferably carried out in an organic solvent. Examples of the organic solvent include NM2P, N, N′-dimethylformamide, N, N-dimethylacetamide, dimethyl Examples thereof include sulfoxide. From the viewpoint of reactivity and the performance of the synthesized resin, it is preferable to use NM2P.

  In general, a polyimide resin produced by an equimolar reaction between PMDA and DDE in NM2P is the cheapest, easy to use and widely used. As the polyamic acid, those having a number average molecular weight of 30000 or more are preferable. As this polyamic acid, it is also possible to use a commercially available polyamic acid varnish (for example, product name: Pyre ML manufactured by IST Co., Ltd.).

  You may add another compounding agent to the heat resistant resin varnish of this invention as needed. Examples include lubricants such as polyethylene, adhesion improvers such as coupling agents, metals, semiconductors and oxides, nitrides, carbides thereof, fillers such as carbon black, and the like.

  The present invention is characterized by using a polyamide-imide resin whose molecular terminal isocyanate functional group is treated and sealed with a blocking agent. When polyamic acid (polyimide resin varnish, etc.) and polyamideimide resin are simply mixed without sealing, the amount of polyamic acid is 20% by weight or more of the total resin amount (total of polyamic acid and polyamideimide resin) In this case, the mixture becomes remarkably high in viscosity and coating coating becomes difficult. On the other hand, if this sealing process is performed, the reaction between the polyimide resin varnish (polyamic acid) and the polyamideimide resin is suppressed, and the viscosity due to mixing is reduced. Can be prevented.

  Sealing the molecular terminal isocyanate functional group of the polyamide-imide resin with a blocking agent is also proposed in JP-A-6-65540. However, this is a proposal as means for improving the lubricity of the surface of the insulated wire, and is intended for a polymer having a polysiloxane functional group, which is different from the problem solving means in the present invention.

  Examples of the blocking agent include alcohols and phenols. Examples of alcohols include methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, methyl carbitol, benzyl alcohol, and cyclohexanol. Examples of phenols include phenol, cresol, and xylenol. Alcohols are preferred from the viewpoint of the physical properties of the cured product after varnish baking.

  For example, when a predetermined amount of the polyamideimide resin and the blocking agent are stirred and mixed at about 70 ° C. for about 2 hours, a polyamideimide resin in which the terminal isocyanate functional groups are sealed with the blocking agent can be obtained.

  The heat resistant resin varnish of the present invention can be obtained by mixing a polyamido acid and a polyamidoimide resin obtained by sealing the molecular terminal isocyanate functional group obtained as described above with a blocking agent. As described above, an increase in viscosity due to mixing is suppressed. Moreover, the heat resistant resin varnish of the present invention gives a cured product having excellent toughness. When the blending ratio of the polyamic acid is 50 wt% or more, it exhibits the same toughness as the cured product obtained from the expensive polyimide resin varnish. Even when the blending ratio of the polyamic acid is less than 50 wt%, the toughness of the cured product obtained from the polyimide resin varnish and the toughness of the cured product obtained from the varnish of only the polyamideimide resin are apportioned based on the blending ratio. It exhibits good toughness far exceeding the predicted value of toughness.

  The compounding ratio of the polyamidoimide resin in which the molecular terminal isocyanate functional group is sealed with a blocking agent and the polyamic acid is preferably 5 to 50 wt% with respect to the total content of the polyamic acid. Item 3).

  If the blending ratio of the polyamic acid is less than 5 wt%, the toughness of the cured product of the obtained heat-resistant resin varnish tends to be insufficient, and conversely, even if it exceeds 50 wt%, the toughness is further improved. Is rarely seen, and conversely increases the material cost.

  The heat-resistant resin varnish of the present invention containing a polyamideimide resin and a polyamic acid preferably has a viscosity of 200000 mPa · s (30 ° C., B-type viscometer) or less. If it exceeds 200,000 mPa · s, uniform coating on the substrate becomes difficult. Alternatively, solvent dilution is required to achieve uniform coating, which increases costs. Further, since a solvent such as NM2P has high hygroscopicity, the polyimide precursor is easily hydrolyzed, and the stability of the varnish is lowered. In addition, since the solid content of the varnish decreases due to solvent dilution, it is difficult to obtain a thick film, which is not preferable. A more preferable viscosity is in the range of 1000 to 100,000 mPa · s.

  The present invention provides a heat-resistant resin film comprising a cured product obtained by baking the heat-resistant resin varnish in addition to the heat-resistant resin varnish and having a film shape or a tube shape (Claim 5). .

  The heat-resistant resin varnish is baked by, for example, applying a heat-resistant resin varnish on a substrate, forming a coating film on the substrate, and then heating the coating film to cure the heat-resistant resin varnish. Done in A cured product is obtained by this baking treatment. At this time, the polyamic acid undergoes a thermal imidization reaction to form an imide ring. Therefore, the baking temperature is higher than that required for forming an imide ring. Application and baking of the heat-resistant resin varnish on the substrate can be carried out by conventional methods. The application of the heat-resistant resin varnish and the baking process may be repeated twice or more.

  As a base material used here, metal base materials, such as a metal rod, a metal wire, and a metal plate, a plastic plate, a plastic rod, a glass plate, etc. are mentioned. When the heat resistant resin film of the present invention is formed on a substrate, the heat resistant resin film can be peeled off from the substrate and used. On the other hand, the heat-resistant resin film can be used as it is, that is, in a state where the heat-resistant resin film is bonded and integrated on the base material, or can be used after being peeled and integrated with another base material. In these cases, the heat-resistant resin composite is characterized by having a base material and a heat-resistant resin film. The present invention also provides this heat-resistant resin composite (claim 6).

  The form of the heat resistant resin film of the present invention is not limited to a film shape (flat plate shape), and a tube-shaped (tubular) film is also included in the heat resistant resin film of the present invention. For example, the heat resistant resin film formed by applying the heat resistant resin varnish of the present invention on a metal rod, metal wire, plastic rod or the like has a tube shape.

  Since the cured product of the heat resistant resin varnish has excellent heat resistance and excellent strength and elongation, that is, high toughness, the heat resistant resin film of the present invention comprising the cured product of the heat resistant resin varnish is also heat resistant. In addition to being excellent in properties, it has high strength and elongation, ie, excellent toughness, exhibits excellent mechanical properties by suppressing breakage due to driving, etc., and is suitably used for driving parts and insulating films of various electric devices.

  The heat-resistant resin varnish of the present invention is inexpensive and a cured product obtained by subjecting the varnish to a high temperature imidization reaction has strength and elongation comparable to polyimide resin, that is, excellent toughness. Moreover, since this heat resistant resin varnish does not have a problem of increasing viscosity, it can be easily applied (formation of a heat resistant resin film).

  The heat-resistant resin film of the present invention has excellent strength and elongation, that is, high toughness, so that damage due to driving is suppressed. The heat-resistant resin film alone or the structure of the heat-resistant resin composite of the present invention As an element, it is used suitably for the drive part of various electric equipment, an insulating film, etc.

  Next, the best mode for carrying out the present invention will be described based on examples, but the scope of the present invention is not limited to these examples.

Examples 1-6
(Preparation of heat-resistant resin varnish)
A molecular weight of 16500, a solid content of 27%, and a viscosity of 3600 mPa · s, a polyamideimide resin varnish (trade name: AE2 manufactured by Taoka Chemical Industry Co., Ltd.) (600 g) was added with 3 g of methanol as a blocking agent and reacted at 70 ° C. for 2 hours. As a result, 603 g of a polyamideimide resin having an isocyanate functional group sealed therein was obtained.

  The resin molecular weight of the resin varnish was determined by GPC (HLC-8220 GPC, manufactured by Tosoh Corporation) using a 1 wt% solution obtained by diluting the resin varnish with NMP. As the carrier solvent, a solution obtained by dissolving LiBr in NM2P was used.

  The polyamideimide resin thus obtained (with the terminal isocyanate functional group sealed) and a polyimide resin varnish having a molecular weight of 35000 and a viscosity of 4200 mPa · s (a polyamic acid varnish manufactured by IST Co., Ltd.) The weight ratio of the polyamideimide resin after baking and the polyimide resin (formed by ring closure of the polyamic acid) is the ratio of the numerical values shown in the rows of PAI and PI in Table 1 ( PAI: PI) was mixed at 25 ° C. for 2 hours to obtain 6 types of heat-resistant resin varnishes having different mixing ratios of polyamideimide resin and polyamic acid.

(Measurement of viscosity of heat-resistant resin varnish)
When the blending ratio (weight ratio) of the polyamideimide resin and the polyamic acid is 50:50 (the blending ratio of Example 6), the viscosity of the heat-resistant resin varnish after mixing thus obtained is the B-type viscosity. It was 6210 mPa · s (measurement temperature: 30 ° C.) when measured using a meter (rotor No. 3, rotation speed: 12 rpm), which is below the viscosity at which coating is possible (200000 mPa · s) and can be applied sufficiently. Met.

  On the other hand, using the same polyamideimide resin varnish and polyimide resin varnish as described above, the mixture was similarly mixed at a weight ratio of 50:50 without blocking the terminal isocyanate functional group, and the viscosity was measured. It was 533,000 mPa · s, which greatly exceeded the viscosity (200000 mPa · s) that can be applied. Even if the viscosity of the varnish is 200,000 mPa · s or more, it can be coated by diluting with a solvent, but it is expensive because an expensive solvent is used. In addition, since a diluent solvent such as NM2P has high hygroscopicity, the polyimide precursor is easily hydrolyzed, and the stability of the varnish is lowered. In addition, since the solid content of the varnish is reduced by solvent dilution, it is difficult to obtain a thick film, and the use of the film is limited.

(Preparation of heat-resistant resin film)
The obtained heat-resistant resin varnish was applied to the outer periphery of a metal wire having a diameter of 1.0 mm, baked using a baking furnace, and then removed from the metal wire to form a tubular film having a thickness of 32 to 34 μm (heat-resistant resin film) Got.

(Physical property evaluation of heat-resistant resin film)
Using the obtained tubular film, the items shown in Table 1 were measured and evaluated by the methods shown below. The results are also shown in Table 1.

  1. Breaking strength, breaking elongation: Using a tensile tester (manufactured by Shimadzu Corp., AG-IS), set the tube-shaped film at a distance between chucks of 20 mm, pull at a speed of 10 mm / min, and measure the strength and elongation when broken. did.

  2. Heat resistance: measured using a dynamic viscoelasticity measuring device (Seiko Instruments, DMS6100) in a nitrogen atmosphere at a heating rate of 10 ° C./min, and the softening temperature of the resin (extrapolation that reduces the dynamic storage modulus) Temperature).

Examples 7-12
To 600 g of polyamideimide resin varnish (molecular weight 22000, solid content 23%, viscosity 4300 mPa · s) obtained by reacting TMA and MDI in NM2P, add 3 g of methanol as a blocking agent, and react at 70 ° C. for 2 hours. Thus, 603 g of a polyamideimide resin in which the terminal isocyanate functional group was sealed was obtained. A tubular film (heat-resistant resin film) was produced by the same method as in Examples 1 to 6 except that this polyamide-imide resin with the terminal isocyanate functional group sealed was used, and the same items were measured and evaluated. . The results are shown in Table 2.

Examples 13-18
To the polyamideimide resin varnish (molecular weight 5500, solid content 30%) 600 g obtained by reacting TMA and MDI in NM2P, 3 g of methanol was added as a blocking agent and reacted at 70 ° C. for 2 hours to obtain a terminal isocyanate function. As a result, 603 g of a polyamideimide resin whose group was sealed was obtained. A tubular film (heat-resistant resin film) was produced by the same method as in Examples 1 to 6 except that this polyamide-imide resin with the terminal isocyanate functional group sealed was used, and the same items were measured and evaluated. . The results are shown in Table 3.

Comparative Examples 1 and 2
Using only one of the same polyamideimide resin (Comparative Example 1) or polyimide resin varnish (Comparative Example 2) as used in Examples 1 to 6, a tubular film ( Heat resistant resin film) was prepared, and the same items were measured and evaluated. These are Comparative Examples 1 and 2, and the results are also shown in Table 1.

Comparative Example 3
Using the same polyamide imide resin as used in Examples 7 to 12 and without using a polyimide resin varnish, a tube-like film (heat-resistant resin film) was produced in the same manner as in Examples 1 to 6, and the same items were used. Was measured and evaluated. These are referred to as Comparative Example 3 and the results are also shown in Table 2.

Comparative Example 4
Using the same polyamide imide resin as used in Examples 13 to 18 and without using a polyimide resin varnish, a tube-like film (heat-resistant resin film) was prepared in the same manner as in Examples 1 to 6, and the same items were used. Was measured and evaluated. The results are also shown in Table 3.

  In Tables 1, 2, and 3, PAI indicates a polyamideimide resin, and PI indicates a polyimide resin.

  Tables 1 and 2 show the results (Examples and Comparative Examples) when using a polyamideimide resin having a molecular weight of 10,000 or more. As is clear from Tables 1 and 2, the heat-resistant resin films obtained in the respective examples are more heat-resistant than the heat-resistant resin films obtained by using only the polyamideimide resin (Comparative Example 1 and Comparative Example 3). The property is excellent. Moreover, it is excellent in breaking strength and / or breaking elongation, and is excellent in toughness.

  Table 3 shows the results of Examples (and Comparative Examples) when a polyamideimide resin having a molecular weight of less than 10,000 is used. As is clear from the comparison between this result and the results shown in Tables 1 and 2, when a polyamideimide resin having a molecular weight of less than 10,000 is used, compared to using a polyamideimide resin having a molecular weight of 10,000 or more. The toughness, particularly the elongation at break, is low, and the molecular weight of the polyamideimide resin is preferably 10,000 or more.

  However, even when a polyamideimide resin having a molecular weight of less than 10,000 is used, the heat resistant resin film obtained in each example is the same as the heat resistant resin film obtained by using only the polyamideimide resin (Comparative Example 4). In comparison, it is excellent in breaking strength and / or elongation at break, and therefore has excellent toughness.

  Based on the results shown in Tables 1 and 2, the relationship between the blending ratio of the polyamic acid (polyimide resin varnish), the breaking strength and the breaking elongation is shown in FIGS. The horizontal axis in FIGS. 1 to 4 represents the compounding ratio of polyamic acid (in the drawings, PI (wt%)), and the vertical axis represents breaking strength (unit MPa) or breaking elongation (%).

  As shown in FIGS. 1 to 4, when about 50 wt% of polyamic acid is blended, excellent breaking strength and breaking elongation comparable to the values shown for polyamic acid alone (100 wt%: Comparative Example 1) are obtained. It has been. Furthermore, even at 50 wt% or less, a good value far exceeding the value (indicated by a dotted line in the figure) predicted by apportioning from the blending ratio is shown.

  When the obtained heat-resistant resin film was analyzed with a scanning probe microscope, a sea-island structure was confirmed, and it was speculated that this sea-island separation structure exhibited high toughness according to the present invention. The schematic structure is shown in FIG.

  That is, as shown in FIG. 5, at the time of stretching, the sea phase (polyimide-rich phase) is greatly deformed to improve elongation at break, and the island phase (polyamideimide-rich phase) exhibits a reinforcing effect. It is presumed that the breaking strength is improved.

It is a graph which shows the relationship between the compounding ratio of the polyamic acid in Examples 1-6 and Comparative Examples 1 and 2, and breaking strength. It is a graph which shows the relationship between the compounding ratio of the polyamic acid in Examples 1-6 and Comparative Examples 1 and 2, and breaking elongation. It is a graph which shows the relationship between the compounding ratio of the polyamic acid in Examples 7-12 and Comparative Examples 2 and 3, and breaking strength. It is a graph which shows the relationship between the compounding ratio of the polyamic acid in Examples 7-12 and Comparative Examples 2 and 3, and breaking elongation. It is a schematic diagram explaining the sea island structure in the resin composition obtained by this invention.

Claims (3)

A polyamidoimide resin having a number average molecular weight of 10,000 or more and having a molecular terminal isocyanate functional group sealed with a blocking agent, and polyamic acid , wherein the polyamic acid content is the sum of the polyamidoimide resin and the polyamic acid A heat-resistant resin varnish characterized by having a viscosity of 5 to 50 wt% and a viscosity at 30 ° C. of 200000 mPa · s or less based on the content. A heat-resistant resin film comprising a cured product obtained by baking the heat-resistant resin varnish according to claim 1 and having a film shape or a tube shape. A heat-resistant resin composite comprising a base material and the heat-resistant resin film according to claim 2 .

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