JPH10218959A - Aromatic polycarbodiimide and film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new aromatic polycarbodiimide which has excellent solubility in organic solvents and can give a film having good processability and excellent heat resistance and humidity resistance. SOLUTION: This polycarbodiimide comprises structural units represented by the formula (wherein X<1> to X<4> are each H or a 1-3C alkyl; and n is 2-400). It can be produced by polymerizing the corresponding diisocyanate monomer in the presence of a phosphorous-containing catalyst by a known process. The diisocyanate may be used alone or in combination with other organic diisocyanates in an amount not detrimental to its properties. The reaction temperature is desirably 40-150 deg.C. In the synthesis of the polycarbodiimide, the isocyanate concentration is 5-70wt.%. The organic solvent used in the synthesis e.g. tetrachloroethylene. The phosphorus-containing catalyst used is exemplified by 1-phenyl-2-phospholene 1-oxide. The number-average molecular weight of the polycarbodiimide is 1,000-100,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to novel aromatic polycarbodiimides. The aromatic polycarbodiimide of the present invention is a film or adhesive having various excellent properties such as high heat resistance,
Provide moldings.

[0002] As the aromatic polycarbodiimide, those obtained by polymerizing diphenylmethane diisocyanate (MDI) or tolylene diisocyanate (TDI) as a monomer have been known. Such polycarbodiimides are used as flame-resistant films and heat-resistant adhesives due to their excellent heat resistance.

[0003]

Objects and Summary of the Invention These polycarbodiimide films have heat resistance in that they do not generate volatile gases or decomposed monomers even when exposed to a high temperature of 400 ° C. or higher, but have low moisture resistance or a temperature of 200 ° C. or higher. When heat-treated, there is no self-holding property, the material becomes brittle, and cannot be put to practical use. Further, the solubility in organic solvents is poor and the processability is low.

[0004] The present inventors have repeatedly studied various aromatic polymers in order to solve such disadvantages of the conventional polycarbodiimides, and as a result, have found the novel polymers of the present invention. That is, the present invention provides an aromatic polycarbodiimide having a structural unit represented by the following general formula (I).

[0005]

Embedded image (In the formula, X ^{1 to} X ⁴ each independently represent hydrogen or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 2 to 200.)

[0006] This polymer is a novel polymer compound, has excellent solubility and very high heat resistance, and also has excellent adhesiveness, low-temperature processability and moisture resistance. In addition, US Patent No. 5,109,097 discloses an aromatic diisocyanate represented by the following formula (II). However, there is no description at all here about polymerizing the aromatic diisocyanate compound and obtaining polycarbodiimide therefrom.

Embedded image

[0007]

DETAILED DESCRIPTION OF THE INVENTION The polycarbodiimides of the present invention
It can be obtained by polymerizing a corresponding diisocyanate represented by the following formula (III) as a monomer in the presence of a phosphorus-based catalyst by a method known per se. Among these monomers, X ^{1 is} preferred in view of availability and reactivity.
X ⁴ is preferably hydrogen, a methyl group or an ethyl group, and particularly preferably X ^{1 to} X ⁴ are all hydrogen.

[0008]

Embedded image (In the formula, X ^{1 to} X ⁴ each independently represent hydrogen or an alkyl group having 1 to 3 carbon atoms.)

The diisocyanate monomer may be used alone, and other organic diisocyanates such as 4,4'-diphenylmethane diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, as long as the properties thereof are not impaired. 1-methoxyphenyl-2,4-diisocyanate, 3,3'-dimethoxy-4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, o -It may be copolymerized with tolylene diisocyanate.

The polymerization temperature is preferably from 40 to 150 ° C.
0-140 degreeC is more preferable. When the reaction temperature is lower than 40 ° C., the reaction time becomes too long and is not practical. Also 150
If the reaction temperature exceeds ℃, it is difficult to select a solvent.

The polyisocyanate monomer concentration in the synthesis of polycarbodiimide is 5 to 70% by weight (hereinafter simply referred to as%), preferably 10 to 60%, most preferably 15%.
５０50%. If the concentration is lower than 5%, carbodiimidization may not proceed. If it exceeds 70%, control of the reaction may be difficult.

The organic solvent used in the synthesis of the polycarbodiimide and in the polycarbodiimide solution may be a conventionally known organic solvent. Specifically, halogenated hydrocarbons such as tetrachloroethylene, 1,2-dichloroethane, and chloroform; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cyclic ether solvents such as tetrahydrofuran and dioxane; toluene, xylene, and benzene And other aromatic hydrocarbon solvents. These may be used alone or in combination of two or more.

The catalyst used for the carbodiimidization includes:
Any known phosphorus-based catalyst is suitably used.
-Phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-2-
Phosphorene-1-oxide, 3-methyl-1-phenyl-2-phospholene-1-oxide, or 3
-Phosphorene oxides, such as -phosphorene isomers.

The terminal blocking treatment may be carried out by adding a monoisocyanate at any of the last stage, the middle stage, the initial stage or the whole of the polymerization reaction. As such a monoisocyanate, phenyl isocyanate, p-nitrophenyl isocyanate, p- or m-tolyl isocyanate, p-formylphenyl isocyanate and the like can be used. The polycarbodiimide solution thus obtained is excellent in storage stability of the solution.

After completion of the reaction, the reaction solution may be poured into a poor solvent such as methanol, ethanol or hexane to precipitate polycarbodiimide as a precipitate, thereby removing unreacted monomers or catalyst. In order to prepare a polycarbodiimide solution, a polymer precipitated as a precipitate is washed and dried by a predetermined operation, and is dissolved again in an organic solvent.
By performing such an operation, the solution stability of the polycarbodiimide can be improved.

Further, the by-products contained in the polymer solution may be adsorbed on a suitable adsorbent or the like and purified. As an adsorbent, for example, alumina gel, silica gel, activated carbon,
Zeolites, activated magnesium oxide, activated bauxite, flour earth, activated clay, molecular sieve carbon and the like can be used alone or in combination.

The molecular weight of the polycarbodiimide of the present invention is
1,000 to 100,000 in number average molecular weight, preferably 4,000
~ 20,000. That is, in the formula (I), n is 2 to 2
It is an integer of 00, preferably an integer of 8 to 40. If the molecular weight of the polycarbodiimide is too high, gelation easily occurs within several minutes to several hours even at room temperature, which is not preferable for practical use. If the molecular weight is too low,
It is not preferable because the reliability of the film is lacking.

(Production of Film and Adhesive Sheet) The polycarbodiimide film (or sheet) of the present invention is formed from a polycarbodiimide varnish to a suitable thickness by a known method (casting, spin coating, roll coating, etc.). It is obtained by doing. The film is usually dried at a temperature necessary for removing the solvent, and the coating temperature is, for example, 20 to 350 ° C., preferably 50 to 25 ° C., so that the curing reaction is not greatly advanced.
0 ° C, more preferably 70 to 200 ° C. If the drying temperature is lower than 20 ° C., the solvent remains in the film, and the reliability of the film becomes poor, which is not preferable. On the other hand, when the drying temperature is higher than 350 ° C., thermal curing of the film tends to proceed.

The polycarbodiimide resin composition of the present invention may contain a fine inorganic filler as long as the processability and heat resistance are not impaired. Various additives such as a smoothing agent, a leveling agent, and a defoaming agent for improving surface smoothness may be added as necessary.

The molded product obtained by molding the polymer of the present invention into a film can be used as a heat-resistant adhesive sheet. The thickness of the film or sheet that can be formed into an adhesive sheet is generally 1 to 200 μm,
The present invention is not limited to this, and can be appropriately selected according to the purpose. Also, the shape and size of the sheet can be appropriately selected according to the adherend such as a lead frame and a semiconductor chip.

When an adhesive sheet is manufactured, for example, aluminum, copper, silver, gold, nickel, chromium, lead, and the like are used in order to impart conductivity, improve heat conductivity, adjust elastic modulus, and particularly increase elastic modulus. Metals such as tin, zinc, palladium and solder, or alloys, ceramics such as alumina, silica, magnesia and silicon nitride, and various other inorganic powders composed of carbon and the like may be blended, if necessary, in one or more kinds. .

Further, these films may be formed on a support to form an adhesive sheet. In order to manufacture the adhesive sheet having such a configuration, a varnish may be coated on the support, or a film may be formed in advance and the film may be laminated by pressing or the like.

Examples of the support used here include a metal foil and an insulating film. As the metal foil, any of aluminum, copper, silver, gold, nickel, indium, chromium, lead, tin, zinc, palladium and the like may be used, and these may be used alone or as an alloy. As the insulating film, any film having heat resistance and chemical resistance, such as polyimide, polyester, and polyethylene terephthalate, may be used.

Further, the metal foil and the insulating film may be used alone, or a two-layer base material such as a metal foil / insulating film obtained by laminating two or more layers thereof may be used. Examples of such a two-layer substrate include a copper / polyimide two-layer substrate.

The sheet adhesive of the present invention is hardened by heat treatment to exhibit a strong adhesive force, and becomes a cured product having low hygroscopicity. In order to perform the heat treatment, for example, an appropriate method such as a heater, ultrasonic waves, or ultraviolet rays may be used. Therefore, the adhesive sheet of the present invention is preferable for the bonding treatment of various materials, and in particular, is required to have a highly reliable fixing treatment, and is therefore required to have low moisture absorption. It is preferable for fixing parts. The adhesive sheet of the present invention is excellent in that it has low hygroscopicity, is flexible and easy to handle, has good adhesiveness to semiconductor elements, and has good storage stability.

(Use) The polycarbodiimide resin thus produced is used as a heat-resistant coating material for various articles. Such articles are not particularly limited, and include, for example, sheets, plates, and rings made of glass, metal, resin, and ceramic. Specific products include electric wires such as power cables, glass bottles, and electronic components. Further, it can be used as an adhesive for electronic components by utilizing its heat resistance. Further, it can be used as a gas / liquid separation membrane.

(Monomer) The isocyanate compound, 9,9-bis (4-isocyanatophenyl) fluorene (formula (II)), which is a raw material of the polycarbodiimide of the present invention, has a precursor, 9,9-bis (4 -Aminophenyl) fluorene can be produced by isocyanation by various methods known per se.

As a method for isocyanating such a diamine compound, there is a method in which phosgene, diphenyl carbonate or carbonyldiimidazole is allowed to act. Alternatively, urethane may be temporarily formed from a diamine compound by using a halogenated alkylformate, and this may be isocyanated in the presence of a catalyst such as chlorosilane or catecholborane. Further, in another method, a method in which a carboxylic acid such as 9,9-bis (4-carboxyphenyl) fluorene is used as a diisocyanate precursor, and this isocyanated by Curtius decomposition may be used.

Among these production methods, a method in which a diamine compound is once converted into urethane by using an alkyl halide or an aryl halide and then isocyanated by using chlorosilane as a catalyst.
(G.Greber.et.al., Angew.Chem.Int.Ed., Vo.l7, No.12,94
1 (1968)) or a method of isocyanation using catechol borane (VLKValli.et.al., J. Org.Chem.,
Vol. 60, 257 (1995)) is preferred in terms of yield and safety.

(Urethane Synthesis) First, urethane is synthesized by reacting a corresponding diamine compound with methyl chloroformate, ethyl chloroformate, phenyl chloroformate, p-nitrophenyl chloroformate, or the like.

The solvent used in these reactions may be any solvent that can dissolve the diamine. Examples thereof include ether compounds such as THF, dioxane, and diethyl ether; aromatic hydrocarbon compounds such as toluene, xylene and benzene; ketone compounds such as acetone and methyl ethyl ketone; and ester compounds such as ethyl acetate. These solvents may be used alone or as a mixture of two or more.

The reaction temperature is from -40 to 100 ° C, preferably from -20 to 60 ° C, most preferably from -10 to 20 ° C.

The base for trapping the hydrogen chloride generated by the reaction may be any base that dissolves in the solvent used and does not inhibit the reaction. For example, triethylamine, sodium hydroxide, pyridine, diazabicycloundecene (DB)
U) and the like.

In order to purify the obtained urethane, conventionally known methods such as recrystallization and column can be used.
Further, distillation may be performed as necessary.

(A) Isocyanation Using Chlorosilane To isocyanate the urethane with chlorosilane, the molar amount of urethane is 1.5 to 4.6 times, preferably 1.7 to 3.0 times, Most preferably, thermal decomposition is carried out using 1.8 to 2.0 times the amount of chlorosilane as a catalyst.

The solvent to be used may be any one which dissolves or suspends urethane, and includes the above-mentioned ether compounds, aromatic hydrocarbons and halogenated hydrocarbons.

The reaction temperature ranges from 0 ° C. to the boiling point of the solvent used. A base such as triethylamine may be similarly used for trapping hydrogen chloride generated during the reaction.
The amount of the base is 1.5 to 4.6 times, preferably 1.7 to 3.0 times, and more preferably 1.8 to 2.0 times the urethane.
It is twice the mmol.

(B) Isocyanation Using Halogenated Catechol Borane For the isocyanation of urethane, a method using a halogenated catechol borane as a catalyst instead of the chlorosilane may be employed. Examples of the halogenated catechol borane include chlorocatechol borane, bromocatechol borane, and the like. As the solvent used for such a reaction, the same solvent as used in the isocyanation using chlorosilane may be used. The reaction temperature is generally -50 to 80C, preferably 20 to 70C, more preferably 20 to 60C. To trap hydrogen chloride produced during the reaction, a base is used in the same manner as described above. After the reaction, the obtained isocyanate monomer can be purified by removing the solvent and performing flash column or recrystallization or distillation under reduced pressure.

The urethanization, isocyanation and carbodiimidization of the diamine may be carried out in a stepwise manner by isolation and purification, and may be carried out in a stepwise manner. It may be performed as a series of reactions.

[0040]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In addition, the characteristic of the obtained polycarbodiimide was measured as follows.

[0041] was measured by using the IR JEOL FT / IR-230.

Thermal Curing Temperature and Glass Transition Point (Tg) The exothermic peak of trimerization was measured using DSC-200 (manufactured by Seiko Denshi Kogyo Co., Ltd.).

Thermal decomposition onset temperature (Td) Measured using TG / DTA300 (manufactured by Seiko Instruments Inc.), and the 5% weight loss temperature was defined as Td.

HLC8120 (manufactured by Tosoh Corporation) as a number average molecular weight apparatus and GM
H _HR -H + GMH _HR -H + G2000 _HR (manufactured by Tosoh Corporation)
It measured using.

[Example 1] (Polycarbodiimidization of 9,9-bis (4-aminophenyl) fluorene) 300
In a 3-mL three-necked flask, 10.0 g (28.7 mmol) of 9,9-bis (4-aminophenyl) fluorene, 240 mL of dichloromethane and 5.80 g of triethylamine (57.
(4 mmol). Next, 8.98 g (57.4 mmol) of phenyl chloroformate was put into the dropping funnel, and the reaction vessel was cooled to 0 ° C. in an ice bath. Phenyl chloroformate was added in a few seconds and stirred overnight while returning to room temperature.

7.53 g of triethylamine (74.
6 mmol), 8.09 g (74.6 mm) of trimethylchlorosilane.
ol) and refluxed for 2 hours. Next, THF10
0 mL, carbodiimidation catalyst (3-methyl-1-phenyl-2-phospholene-1-oxide) 0.441 g (2.
30 mmol) and 5 ml of dichloromethane are distilled off.
The mixture was stirred at 5 ° C for 2 hours and refluxed for 5 hours. The generated salt was removed by filtration. Furthermore, n-hexane 1.75
L, and dried under reduced pressure at 30 ° C. for 8 hours to obtain 7.00 g of polycarbodiimide as a white powder.
(19.7 mmol, 69%). The number average molecular weight of this polycarbodiimide was 2,800. The carbodiimidization was confirmed by IR (see FIG. 1).

The above white powder was soluble in organic solvents such as THF, cyclohexanone and chloroform. Also, 0.6 g of this white powdery form is 1.8 g of cyclohexanone.
Cast the varnish dissolved in to a glass plate,
The film was dried at 200 ° C. for 20 minutes to obtain a film. Also,
Even after drying at 250 ° C. for 20 minutes and at 300 ° C. for 20 minutes, it was flexible. As a result of measuring the thermosetting temperature, the thermal decomposition onset temperature, and the glass transition temperature of the obtained film, they were 390 ° C, 505 ° C, and 185 ° C, respectively.

[Comparative Example 1] 10 mg (40 mmol) of MDI in 50 mL of THF was added to 60 mg of carbodiimidization catalyst (1-phenyl-3-methylphospholene oxide) (0.3 mg).
(1 mmol) at 60 ° C. for 2 hours. The reaction solution was cast on a glass plate to form a film. The thermosetting temperature of this film is 350 ° C.,
When heat treatment was performed at 250 ° C. for 1 hour, discoloration was observed, resulting in loss of flexibility and loss of self-preservation.

Comparative Example 2 The white powdered polycarbodiimide obtained by reprecipitating the reaction solution of Comparative Example 1 was not redissolved in an organic solvent such as THF, cyclohexanone, toluene and acetone.

[0050]

The polycarbodiimide of the present invention has high solubility in organic solvents, good processability, and excellent heat resistance.
It exhibits moisture resistance and can be used as a heat-resistant coating material and the like in a soldering step in the production of electronic components and as a gas separation membrane.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of a polymer obtained in Example 1.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Shu Mochizuki 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation

Claims (3)

[Claims] 1. An aromatic polycarbodiimide having a structural unit represented by the following general formula (I). Embedded image (In the formula, X ^{1 to} X ⁴ each independently represent hydrogen or an alkyl group having 1 to 3 carbon atoms, and n represents an integer of 2 to 200.) 2. A polycarbodiimide solution obtained by dissolving the aromatic polycarbodiimide according to claim 1 in an organic solvent. 3. A polycarbodiimide film comprising the aromatic polycarbodiimide of claim 1.