JP2004189793A - Preparation method of polyimide resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of preparing a polyimide resin that can industrially advantageously prepare a polyimide resin which has a very high utility value as electric/electronic materials, is excellent in heat resistance and fabricability and has a stable quality without using an organic solvent. <P>SOLUTION: In the preparation method of the polyimide resin, a tetracarboxylic dianhydride and a diamine are kneaded using a kneader without any solvent and reacted through shear heating. Here, the tetracarboxylic dianhydride and the diamine are both in solid states and preferably have average particle sizes of ≤30 μm. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a polyimide resin.
[0002]
[Prior art]
BACKGROUND ART Polyimide resins are widely used in the fields of electric and electronic materials because of their high heat resistance, flame retardancy, and excellent electrical insulation. Specifically, the film may be used as a substrate of a flexible printed wiring board or a heat-resistant adhesive tape, and the resin varnish may be used as a semiconductor insulating film or protective film.
[0003]
Conventionally, as a method for producing a polyimide resin, a tetracarboxylic dianhydride and a diamine are reacted in an organic solvent to produce a polyamic acid solution, which is further heated or chemically closed to obtain a polyimide resin, A solution thermal ring closure method and a chemical ring closure method are generally known (for example, see Patent Document 1). In these methods, a very polar organic solvent must be used to dissolve the generated polyamic acid. Many organic polar solvents are harmful, and easily absorb moisture in the air. Tetracarboxylic dianhydride reacts with moisture to open the ring to form a carboxylic acid, which reduces the reaction activity. Therefore, it was necessary to purchase an expensive and highly pure organic polar solvent to prevent moisture absorption. Furthermore, a two-step process of polyamic acid generation and imidization is required, which is long and industrially very disadvantageous.
[0004]
On the other hand, as a method for producing a polyimide resin without using an organic solvent, tetracarboxylic dianhydride and diamine, after mixing a solid mixture obtained by mixing in a mortar or a mixer on a tray, using a dryer or the like There is a method of performing a heat treatment to obtain a polyimide resin (for example, see Patent Document 2). However, in this method, since the materials are not mixed at the time of the heat treatment, not only is it difficult to synthesize a high molecular weight polyimide resin, but also when a reaction is performed by combining a plurality of raw materials, a good random polymer is obtained. Difficult to form. Further, it is not suitable as an industrial production system.
[0005]
[Patent Document 1]
JP-A-5-33128 [Patent Document 2]
JP 2000-302865 A
[Problems to be solved by the invention]
The present invention has been made in order to solve these conventional problems, the purpose of which is to provide a polyimide resin suitable for the field of electric and electronic materials, which has excellent heat resistance and stable quality. It is an object of the present invention to provide a method for efficiently producing a compound in a short time without using an organic solvent.
[0007]
[Means for Solving the Problems]
That is, the present invention
(1) A method for producing a polyimide resin, comprising kneading a tetracarboxylic dianhydride and a diamine using a kneader without using a solvent, and reacting with shear heat.
(2) The method for producing a polyimide resin according to (1), wherein the tetracarboxylic dianhydride and the diamine are solid, and both have an average particle diameter of 30 μm or less.
(3) The method for producing a polyimide resin according to (1) or (2), wherein the reaction equivalent ratio of the tetracarboxylic dianhydride to the diamine is in the range of 0.8 to 1.2.
(4) The method for producing a polyimide resin according to any one of (1) to (3), wherein the reaction is performed by controlling the heat generated by shearing in the kneader within a temperature range of 80 to 400 ° C.
(5) The method for producing a polyimide resin according to any one of (1) to (4), wherein the kneader is a pressure kneader.
(6) The method for producing a polyimide resin according to any one of (1) to (4), wherein the kneader is a co-rotating twin-screw extruder.
It is.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The tetracarboxylic dianhydride used in the present invention is not particularly limited, and those similar to those used in conventional polyimide synthesis can be used. For example, pyromellitic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetra Aromatic tetracarboxylic dianhydrides such as carboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfonetetracarboxylic dianhydride and 4,4'-(hexafluoroisopropylidene) diphthalic dianhydride And aliphatic tetracarboxylic dianhydrides such as cyclobutanetetracarboxylic dianhydride and cyclopentanetetracarboxylic dianhydride. These can be used alone or in combination of two or more.
[0009]
The diamine component used in the present invention is not particularly limited, and the same diamine component as used in conventional polyimide synthesis can be used. For example, 1,3-bis (3-aminophenoxy) benzene, 2,2′-bis (4- (4-aminophenoxy) phenyl) propane, 2,5-dimethyl-p-phenylenediamine, 2,4-dimethyl Aromatic diamines such as m-phenylenediamine, 2,2′-bis (4-aminophenoxy) hexafluoropropane, and diamines having a polysiloxane structure such as α, ω-bis (3-aminopropyl) polydimethylsiloxane Compounds can be mentioned. These diamines can be used alone or in combination of two or more.
[0010]
Further, for the purpose of controlling the molecular weight of the obtained polyimide resin and maintaining processability, it is also possible to add a small amount of an acid anhydride or an aromatic amine as an endcapping agent to carry out the reaction. Examples of the acid anhydride as the end cap agent include phthalic anhydride, maleic anhydride, and nadic anhydride, and examples of the aromatic amine include p-methylaniline, p-methoxyaniline, and p-phenoxyaniline. It is preferable that the amount of the acid anhydride or aromatic amine to be added is 5 mol% or less. If it exceeds 5 mol%, the molecular weight of the obtained polyimide resin is remarkably reduced, which may cause problems in heat resistance and mechanical properties. Furthermore, various additives such as fillers can be added simultaneously as long as the performance is not impaired.
[0011]
The reaction equivalent ratio between the tetracarboxylic dianhydride and the diamine component in the synthesis of polyimide is an important factor that determines the molecular weight of the obtained polyimide resin. In general, it is well known that there is a correlation between the molecular weight of a polymer and mechanical properties, and the higher the molecular weight, the better the mechanical properties. Therefore, in order to obtain a practically excellent strength polyimide resin, it is necessary to have a high molecular weight to some extent. The equivalent ratio of the tetracarboxylic dianhydride to the diamine component is preferably in the range of 0.8 to 1.2, and more preferably 0.9 to 1.1. If it is less than the lower limit, the molecular weight is low and the material is brittle, so that the mechanical strength is weak. On the other hand, if it exceeds the upper limit, unreacted carboxylic acid may be decarbonated during heating to cause gas generation and foaming, which may be undesirable.
[0012]
In the present invention, the tetracarboxylic dianhydride and the diamine are kneaded using a kneader without using an organic solvent, and the reaction is performed by shearing heat generation. Generally, tetracarboxylic dianhydrides and diamines are solids, but the finer the powder particles, the more uniform the reaction can be performed, and the higher the probability of contact between monomers, the faster the reaction proceeds. When a plurality of raw materials are used in combination, a good random polymer can be obtained. However, many commercially available raw materials contain a large amount of coarse particles and have a large average particle size. In such a case, a raw material previously ground by a known pulverizer is used for the reaction. The average particle diameter of both the tetracarboxylic dianhydride and the diamine is preferably 30 μm or less, more preferably 20 μm or less.
[0013]
Regarding the introduction of the above-mentioned raw materials into the kneading machine, a tetracarboxylic dianhydride and a diamine each separately measured may be charged, or a pre-mixed one in a blender or the like may be used. . In addition, as for the liquid diamine component such as the diamine compound having the above-mentioned polysiloxane structure, a predetermined amount may be dropped directly into the kneader, or solidified when mixed with tetracarboxylic dianhydride, The solidified mixture may be charged.
[0014]
In general, it is known that the reaction between tetracarboxylic dianhydride and diamine generates condensed water with the progress of imidization. If this condensed water is not efficiently removed from the reaction system, the acid anhydride will be opened to form a carboxylic acid, and a molecule having low reaction activity will be generated, and the molecular weight of the polyimide resin may not be increased. Therefore, it is preferable that the kneading machine used in the present invention has a mechanism for removing water vapor of condensed water generated by imidization in the initial stage of kneading, or a device capable of discharging water vapor by a simple operation.
[0015]
In the present invention, any of a batch type and a continuous type kneader can be used. Examples of the batch kneader include a pressure kneader, a Banbury mixer, a Brabender and the like. In particular, a pressurized kneader that can easily discharge water vapor generated by imidation by opening and closing the pressurized lid and that can control the shear applied to the material by adjusting the pressing force is preferable.
Regarding the operating conditions of the batch-type kneader, it is preferable that the reaction between the tetracarboxylic dianhydride and the diamine is carried out in a temperature range of 80 to 400 ° C. using the heat generated by shearing. If the reaction temperature is lower than 80 ° C., the reaction rate is rapidly reduced, so that many unreacted substances are not obtained, and a sufficiently high-molecular-weight polyimide resin cannot be obtained.If the temperature exceeds 400 ° C., the polymer may be thermally decomposed. Yes, both are not preferred. Regarding the heating method, forcible heating can also be performed using an electric heater, a heating medium jacket, etc. provided in the kneading machine, but sufficient heating is possible by simply utilizing the shear heat generated by kneading, and external heating can be performed. It is preferable from the viewpoint of energy cost that the apparatus is preliminarily heated before starting kneading.
[0016]
On the other hand, examples of the continuous kneader include extruders such as a single screw extruder and a twin screw extruder. As the single screw extruder, in addition to an extruder having a general full flight screw, a single screw extruder having a discontinuous flight screw, a pin barrel, a mixing head, and the like can be used. Further, the twin-screw extruder may use any of a meshing co-rotating type, a meshing different direction rotating type, and a non-meshing different direction rotating type. In particular, a co-rotating twin-screw extruder which partially has a kneading disk element and has excellent self-wiping properties is preferably used.
[0017]
The above-mentioned extruders preferably have at least one unit processing zone comprising a kneading section and a vent section. In the kneading section, the mixing function is more important than the material transfer function, and the raw materials are sufficiently mixed by kneading. The reaction is allowed to proceed, and then the water vapor generated by imidization is removed from the vent hole provided in the vent part by vacuum suction with a vacuum pump or removed by atmospheric release.
[0018]
The barrel temperature of the extruder is preferably controlled in the temperature range of 80 to 400 ° C. for the same reason as in the case of the batch kneader described above. Normally, the barrel temperature is controlled by external heating using an electric heater or the like and external cooling using water cooling. However, shear heat generated by kneading the material inside the extruder can be used as a heating source. The temperature profile in each barrel depends on the type of tetracarboxylic dianhydride and diamine used and the average residence time. However, in essence, in the former part of the extruder, the reaction proceeds rapidly, and the temperature is raised while suppressing shear heat generation within a range that does not cause a situation in which the water vapor generated in large amounts by imidization cannot be sufficiently removed. It is preferable that the temperature of each stage is set so that the polymer has a viscosity at which the polymer can be discharged at the subsequent stage. The L / D of the extruder (the ratio of the screw length to the screw diameter) is appropriately selected according to the type of raw material used, the screw configuration, and the like. However, if it is too small, the polymerization reaction may not be performed sufficiently. , L / D = 10 or more.
[0019]
The polyimide resin thus obtained can be pulverized and used as it is as a raw material for molding. A polyimide resin soluble in an organic solvent can be dissolved in an organic solvent and used as a resin varnish in the same manner as a conventional polyimide resin varnish.
[0020]
【Example】
Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. In each example, APB is 1,3-bis (3-aminophenoxy) benzene, BAPP is 2,2′-bis (4- (4-aminophenoxy) phenyl) propane, and 25 DPX is 2,5-bis. Dimethyl-p-phenylenediamine, 24 DPX was 2,4-dimethyl-m-phenylenediamine, APPS was α, ω-bis (3-aminopropyl) polydimethylsiloxane (average molecular weight 862 in terms of amine equivalent), ODPA Is 4,4'-oxydiphthalic dianhydride, BPDA is 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, BTDA is 3,3', 4,4'-biphenyltetracarboxylic acid Dianhydride and PMDA are shorthands for pyromellitic dianhydride. The method for measuring physical properties in each example is as follows.
[0021]
(Weight average molecular weight)
Using a column (TSKgel α-M: 2 columns) manufactured by Tosoh Corporation, flow rate: 1.0 ml / min, eluent: N-methyl-2-pyrrolidone solution containing 0.01 mol / L lithium bromide, column It was measured by gel permeation chromatography (hereinafter abbreviated as GPC) using monodispersed polystyrene as a standard substance using an RI detector under the analysis conditions at a temperature of 40 ° C.
[0022]
(Example 1)
A blend raw material premixed with 209.70 g (0.676 mol) of ODPA having an average particle size of 6 μm, 98.76 g (0.338 mol) of APB having an average particle size of 5 μm, and 291.54 g (0.338 mol) of APPS was previously mixed with 80 The mixture was put into a pressurized kneader (ML-500, manufactured by Moriyama Seisakusho) that had been heated to ℃. Kneading was started under the conditions of a screw rotation speed of 60 rpm and a pressure lid pressure of 0.6 MPa. When the resin temperature reached 105 ° C. due to heat generation, the pressure lid was opened, and kneading was performed for 30 minutes while discharging water vapor generated by imidization. After that, the pressure lid was closed again, and kneading was continued for 55 minutes. The total time required for kneading was 90 minutes, and the resin temperature reached a maximum of 230 ° C. due to shear heat generation. After completion of the kneading, the resin was taken out from the pressure kneader to obtain 582 g of a polyimide resin. The weight average molecular weight of the polyimide resin measured by GPC was 96,500.
[0023]
(Example 2)
A blended raw material premixed with 210.10 g (0.715 mol) of BPDA having an average particle diameter of 25 μm, 205.10 g (0.500 mol) of BAPP having an average particle diameter of 9 μm, and 184.80 g (0.214 mol) of APPS was previously mixed with 90 parts. Into a pressurized kneader (Model ML-500, manufactured by Moriyama Seisakusho) heated to 80 ° C, kneading was started under the conditions of a screw rotation speed of 80 rpm and a pressure of a lid of 0.6 MPa. Was reached, the pressure lid was opened, kneading was performed for 30 minutes while discharging water vapor generated by imidization, then the pressure lid was closed again, and kneading was continued for 55 minutes. The total time required for kneading was 90 minutes, and the resin temperature reached a maximum of 245 ° C. due to shear heat generation. After completion of the kneading, the resin was taken out from the pressure kneader to obtain 585 g of a polyimide resin. The weight average molecular weight of the polyimide resin measured by GPC was 84,200.
[0024]
(Example 3)
122.56 g (0.381 mol) of BTDA having an average particle diameter of 24 μm, 82.97 g (0.381 mol) of PMDA having an average particle diameter of 18 μm, 187.26 g (0.457 mol) of BAPP having an average particle diameter of 9 μm, and 6 μm of average particle diameter A blended material obtained by premixing 10.35 g (0.076 mol) of 24 DPX and 196.85 g (0.228 mol) of APPS was put into a pressurized kneader (Model ML-500 manufactured by Moriyama Seisakusho) which had been heated to 80 ° C. in advance. Then, kneading is started under the conditions of a screw rotation speed of 60 rpm and a pressure lid pressure of 0.5 MPa. When the resin temperature reaches 105 ° C. due to heat generation, the pressure lid is opened, and water vapor generated by imidization is discharged. After kneading for 30 minutes, the pressure lid was closed again, and kneading was continued for 55 minutes. The total time required for kneading was 90 minutes, and the resin temperature reached a maximum of 228 ° C. due to shear heat generation. After completion of the kneading, the resin was taken out from the pressure kneader to obtain 579 g of a polyimide resin. The weight average molecular weight of the polyimide resin measured by GPC was 88,200.
[0025]
(Example 4)
18.11 g (0.083 mol) of PMDA having an average particle diameter of 8 μm, 11.23 g (0.042 mol) of APB having an average particle diameter of 5 μm, 1.13 g (0.008 mol) of 25 DPX having an average particle diameter of 8 μm, and 28.64 g of APPS ( 0.033 mol) was put into a Labo Plastomill (30C150, manufactured by Toyo Seiki Seisakusho) preheated to 80 ° C., and kneaded for 90 minutes at a screw rotation speed of 60 rpm. Was done. Since this apparatus does not have a completely closed structure, it was visually confirmed that water vapor generated by imidization was discharged from the apparatus during kneading. The total time required for kneading was 90 minutes, and the resin temperature reached a maximum of 252 ° C. due to shear heat generation. After completion of the kneading, the resin was taken out from the Labo Plastomill to obtain 57 g of a polyimide resin. The weight average molecular weight of the polyimide resin measured by GPC was 98,300.
[0026]
(Example 5)
A co-rotating twin-screw extruder (screw diameter 25 mm) in which five segment-type barrels each having a unit processing zone consisting of a kneading part and a vent part, which is composed of a self-wiping double-screw element and a kneading disk element, are joined. , L / D = 60) at 400 rpm. Next, the same premixed blended raw material as in Example 1 was supplied to an extruder at a rate of 720 g / h, and a reaction was performed with a residence time of 45 minutes. In order to avoid rapid imidization due to heat generated by shearing and generation of a large amount of water vapor at one time, each barrel is composed of a first barrel 110 ° C., a second barrel 120 ° C., a third barrel 140 ° C., and a fourth barrel 180 ° C. The temperature was controlled at 200 ° C. in the fifth barrel, and water vapor was gradually removed from each vent portion by suction under reduced pressure (9 kPa). The strand-like polyimide resin was recovered through a die attached to the extruder tip. The weight average molecular weight of the obtained polyimide resin measured by GPC was 97,100.
[0027]
(Example 6)
A co-rotating twin-screw extruder (screw diameter 25 mm) in which six segment-type barrels each having a unit processing zone composed of a kneading part and a vent part and composed of a self-wiping type double-screw element and a kneading disk element are joined. , L / D = 75) at a screw rotation speed of 300 rpm. Next, the same premixed blended raw material as in Example 2 was supplied to an extruder at a rate of 900 g / h, and a reaction was performed for a residence time of 60 minutes. In order to avoid rapid imidization due to shear heat generation and the generation of a large amount of water vapor at a time, each barrel is composed of a first barrel 110 ° C, a second barrel 120 ° C, a third barrel 140 ° C, and a fourth barrel 160 ° C. The temperature was controlled at a temperature of 180 ° C. in the fifth barrel and 220 ° C. in the sixth barrel, and water vapor was gradually removed from each vent by vacuum suction (9 kPa). The strand-like polyimide resin was recovered through a die attached to the extruder tip. The weight average molecular weight of the obtained polyimide resin measured by GPC was 88,400.
[0028]
(Comparative Example 1)
720 g of dehydrated and purified N-methyl-2-pyrrolidone is placed in a 4-neck 2 L separable flask equipped with a dry nitrogen gas inlet tube, a heat exchanger, a stirrer, and a thermometer, and vigorously stirred for 10 minutes while flowing nitrogen gas. Next, 49.38 g (0.169 mol) of APB and 145.77 g (0.169 mol) of APPS are charged, and the system is heated to 60 ° C. and stirred until uniform. After homogeneous dissolution, the system was cooled to 10 ° C. and 104.85 g (0.338 mol) of ODPA was added over 15 minutes. While maintaining the temperature of the flask at 10 ° C., stirring was continued for 3 hours to obtain a polyamic acid solution. The nitrogen gas inlet tube and the heat exchanger were removed, and a Dean-Stark tube filled with toluene was connected and attached to the flask, and 180 g of toluene was added to the system. The temperature was raised while condensed water generated by imidization was removed outside the system, and the reaction was continued until water generation from the system was no longer observed, thereby obtaining 980 g of a polyimide resin solution. The maximum internal temperature was 182 ° C., and the imidization required a total of 6 hours, and the total time required from the synthesis of the polyamic acid to the imidation required a long time of 10 hours. The weight average molecular weight of the polyimide resin obtained by GPC measurement was 89,800.
[0029]
(Comparative Example 2)
104.85 g (0.338 mol) of ODPA having an average particle diameter of 22 μm, 49.38 g (0.169 mol) of APB having an average particle diameter of 18 μm, and 145.77 g (0.338 mol) of APPS were put into a mortar and mixed for 30 minutes. A solid mixture was obtained. This solid mixture was spread on a tray and subjected to a heat treatment in a dryer at 200 ° C. for 1 hour to obtain 280 g of a polyimide resin powder. The total time required for the process was 90 minutes, and the weight average molecular weight of the polyimide resin obtained by GPC measurement was 26800 because the polymerization reaction did not sufficiently proceed because mixing was not performed during heating.
[0030]
From the above Examples and Comparative Examples, according to the method for producing a polyimide resin of the present invention, without using an organic solvent, by a very simple operation, it is possible to synthesize the polyimide resin in a short time, industrial production method It can be seen that this is suitable.
【The invention's effect】
According to the method of the present invention, a tetracarboxylic acid dianhydride and a diamine are mixed using a kneader without using a harmful and expensive organic solvent, and a very simple process of reacting by shearing heat generation. In addition, a polyimide resin can be obtained, and the time required for the process is shorter than that of a conventional polyimide synthesis method using a polyamic acid using an organic solvent, which is suitable as an industrial method for producing a polyimide resin.

Claims (6)

A method for producing a polyimide resin, comprising kneading a tetracarboxylic dianhydride and a diamine without using a solvent by using a kneader, and reacting with shear heat. The method for producing a polyimide resin according to claim 1, wherein the tetracarboxylic dianhydride and the diamine are solid, and both have an average particle size of 30 µm or less. 3. The method for producing a polyimide resin according to claim 1, wherein the reaction equivalent ratio of the tetracarboxylic dianhydride to the diamine is in the range of 0.8 to 1.2. The method for producing a polyimide resin according to any one of claims 1 to 3, wherein the reaction is performed by controlling the heat generated by shearing in the kneader within a temperature range of 80 to 400C. The method for producing a polyimide resin according to any one of claims 1 to 4, wherein the kneader is a pressurized kneader. The method for producing a polyimide resin according to any one of claims 1 to 4, wherein the kneader is a co-rotating twin-screw extruder.