JP2000344849A - Aromatic polycarbodiimide and sheet made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polycarbodiimide having a high solubility in an organic solvent and good processability and giving a product excellent in properties such as high heat resistance, low hygroscopicity, and a low permittivity by using a specified diisocyanate as the monomer and polymerizing the monomer. SOLUTION: Isocyanato groups are introduced into a diamine represented by formula III by the action of phosgene, diphenyl carbonate, or carbonyldiimidazole to obtain a diisocyanate monomer represented by formula II. The diisocyanate monomer is polymerized in the presence of a phosphorus catalyst to obtain an aromatic polycarbodiimide having structural units represented by formula I (wherein n is 2-300). Within the scope not detrimental to the properties of the polycarbodiimide, it is possible that a monomer of formula II is copolymerized with another organic diisocyanate such as 4,4'- diphenylmethane diisocyanate or that the polycarbodiimide is used in the form of a mixture after being mixed with a varnish form another polycarbodiimide.

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 can be used as a sheet (film), adhesive, or molded product having various excellent properties such as high heat resistance, low moisture absorption, and low dielectric constant.

[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 conducted various studies in order to eliminate such disadvantages of the conventional polycarbodiimide. As a result, they have found that the above-mentioned problems can be solved by the following polycarbodiimide having a novel skeleton, and have completed the present invention.

That is, the present invention provides the following formula (I):

Embedded image (In the formula, n represents an integer of 2 to 300.) An aromatic polycarbodiimide having a structural unit represented by the formula:

This polymer is a novel polymer compound and has excellent heat resistance and moisture resistance.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The polycarbodiimide of the present invention has the following formula (II):

Embedded image Can be obtained by polymerizing a diisocyanate represented by the following formula in a known manner in the presence of a phosphorus-based catalyst. It should be noted that the monomer formula (II) as a raw material of the polycarbodiimide of the present invention is a novel compound.

The polycarbodiimide of the present invention has the following formula (II)
Diamines represented by I) ( SH Hsiao et. Al. Macromo
l. Chem. Phys. 196 . 3041 (1995) and JP-A-4-178358) as a raw material, isocyanate it by a known method, and then polymerized to produce the compound.

[0009]

Embedded image

(Production of Monomer) As a method for obtaining a diisocyanate represented by the above formula (II) from such a diamine, a method in which phosgene, diphenyl carbonate, or carbonyldiimidazole is allowed to act on the corresponding diamine, or a method in which a dicarboxylic acid is used From Curtius rearrangement.

Further, as another method, a dicarbamate is synthesized by reacting a diamine compound with a halogenated formate such as a halogenated alkyl formate or a halogenated aryl formate, and a halogenated compound such as chlorosilane is used as an activating reagent. Method for diisocyanation by thermal decomposition using a silicon compound (JP-A-10-158394)
No., G. Greber. Et. Al., Angew. Chem. Int. Ed., Vo.
l. 17, No. 12, 941 (1968)) and a method of diisocyanation using catechol borane (VLKValli.et.al., J. Or.
g. Chem., Vol. 60, 257 (1995)), and these methods are more preferable in terms of yield and safety.

(Production of Carbamate) First, in the production of carbamate, the diamine may be reacted directly with a halogenated formate in the presence of a tertiary amine, or the diamine may be activated as a silylated diamine and then halogenated. Formate may be reacted. Below,
The method for obtaining an isocyanate using a silylated diamine as an active intermediate will be described in more detail.

(Synthesis of silylated diamine) As a method for silylating such a diamine compound, a method of reacting an organic silicon halide compound with a corresponding diamine in the presence of a basic compound is used (Oishi, et. Al.). . Ma
cromolecules, 21 , 547 (1988), Oishi, et.al. J. ofP.
olym. Sci., Part A, 25 , 2493 (1987), Oishi, et.
l. Macromol. Chem., Rapid Commun., 12 , 465 (199
1)). That is, it is synthesized by reacting the corresponding diamine compound with an organic silicon halide compound, specifically, trimethylchlorosilane, triethylchlorosilane, chlorosilanes such as trimethoxychlorosilane, etc., but from the viewpoint of ease of handling and economy, Trimethylchlorosilane is most preferred. Further, a method using hexamethyldisilazane can also be adopted. These organic silicon halide compounds may be used alone or in combination of two or more. The amount of the organic silicon halide compound used is preferably 1.5 to 3.4 times the number of moles of the diamine, and more preferably 1.8 to 3.0 times. If the amount is less than this, the reaction does not proceed completely, which is not preferable. On the other hand, if it is more than the above range, it is difficult to remove the unreacted organic silicon halide compound after the completion of the reaction, which is not preferable.

The solvent used in these reactions may be any solvent that can dissolve the diamine. For example, ether compounds such as tetrahydrofuran (THF), dioxane and diethyl ether; ketone compounds such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ester compounds such as ethyl acetate; aromatic hydrocarbons such as toluene, xylene and benzene Halogenated hydrocarbons such as chloroform, methylene chloride, and tetrachloroethylene. These solvents may be used alone or as a mixture of two or more.

The diamine concentration in the reaction mixture is 1 to 50.
%, Preferably 5-40%, optimally 10-30%. If the concentration is too low, the reaction requires time, which is not practical. If the concentration is too high, an undesired side reaction may be caused or control of the reaction may be difficult.

The reaction temperature is 0 to 150 ° C., preferably 20
~ 130 ° C. If the reaction temperature is lower than this, the reaction does not easily proceed and is not practical. If the reaction temperature is higher than this, it is difficult to select a solvent, and a side reaction such as condensation may occur.

The basic compound for trapping hydrogen chloride generated by the reaction may be any compound which dissolves in the used solvent and does not inhibit the reaction, and may be either an organic base or an inorganic base. Organic bases are preferred because they are easily soluble in solvents. In particular, triethylamine, pyridine and 1,8-diazabicyclo do not inhibit the reaction.
Tertiary amines such as [5.4.0] -7-undecene, collidine, picoline and lutidine are preferred. The amount of the base used is preferably 1.5 to 3.4 times the number of moles of the diamine used, and is 1.8 to 1.8 times.
3.0 times is more preferable.

(Synthesis of diisocyanate from silylated diamine) Next, the silylated diamine is reacted with a halogenated formate to obtain a carbamate compound. As the halogenated formate, methyl chloroformate, ethyl chloroformate, phenyl chloroformate, p-nitrophenyl chloroformate and the like are used, but in order to obtain a sufficiently activated carbamate for obtaining polycarbodiimide. Is more suitably phenyl chloroformate or p-nitrophenyl chloroformate. These halogenated formates may be used alone or in combination of two or more. Alternatively, by using two or more kinds of halogenated chloroformates, an asymmetric carbamate compound, one of which is inactive to isocyanation, may be formed in advance, and this may be used as a substitute for the terminal blocking agent.

The reaction temperature is from -40 ° C to 100 ° C, preferably from -20 ° C to 80 ° C. In order to prevent side reactions, the reaction may be carried out while cooling appropriately with an ice bath or the like. The amount of the halogenated formate used is 1.5 to 1.5 moles of the diamine.
It is preferably 3.4 times, most preferably 1.8 to 3.0 times. If the amount used is too small, unreacted diamine or silylated diamine remains in the system, which may cause side reactions such as formation of isocyanate and urea, which is not preferable. If the amount is too large, it is difficult to remove from the system after completion of the reaction. As the reaction between the silylated diamine and the halogenated formate proceeds, the organic silicon halide compound is regenerated. The regenerated organic silicon halide compound acts as an activating reagent for the next isocyanation reaction.

As a basic compound which accelerates the reaction when producing an isocyanate from a carbamate compound, a tertiary amine having a relatively basic property such as triethylamine is more preferable. The reaction temperature for isocyanation is 0 ° C to 16 ° C.
0 ° C., preferably 20 ° C. to 140 ° C. At a low temperature of 0 ° C. or lower, the reaction may not proceed, and at a high temperature of 160 ° C. or higher, a side reaction such as decomposition of a reaction product may occur. The amount of the base used is preferably 1.5 to 3.4 times the number of moles of the diamine used, and most preferably 1.8 to 3.0 times. Next, the diisocyanate thus synthesized is isolated and purified, or is polymerized as it is to obtain a polycarbodiimide.

(Production of polycarbodiimide from diisocyanate) In order to produce the polycarbodiimide of the present invention, the diisocyanate monomer represented by the formula (II) may be used alone. Other organic diisocyanates, for example, 4,4'-diphenylmethane diisocyanate, 2,6
-Tolylene diisocyanate, 2,4-tolylene diisocyanate, 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-tolylene diisocyanate, 2,2-bis [4- (4-isocyanatophenoxy) phenyl] hexafluoropropane, 2,2-bis
It may be copolymerized with [4- (4-isocyanatophenoxy) phenyl] propane or the like.

The copolymerization ratio is from 1 to 90 mol%, more preferably from 1 to 70 mol%, most preferably from 1 to 50 mol%, based on the diisocyanate monomer represented by the formula (II).
If the copolymerization ratio exceeds 90 mol%, the properties of the polycarbodiimide of the present invention may be lost. Moreover, 1/100 to 100/1 with respect to the polycarbodiimide of the present invention.
And other polycarbodiimides may be mixed and used in a varnish state at a ratio of.

The polymerization temperature is preferably 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 concentration of diisocyanate monomer in the synthesis of polycarbodiimide is 1 to 70% by weight (hereinafter simply referred to as%
), Preferably 5-60%, most preferably 15%
~ 50%. If the monomer concentration is lower than 1%, carbodiimidization may not proceed. If it exceeds 70%, control of the reaction becomes difficult.

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

As the catalyst used for the carbodiimidization, any known phosphorus-based catalyst is suitably used.
Phenyl-2-phospholene-1-oxide, 3-methyl-2-phospholene-1-oxide, 1-ethyl-2-phospholene-1-oxide, 3-methyl-1-phenyl-
2-phospholene-1-oxide, or 3-
Phosphorene oxides such as phosphorene isomers are included.

It is to be noted that the above diamine is carbamate,
In diisocyanation and carbodiimidization, isolation and purification may be performed in each step, and the steps may be performed in a stepwise manner, or these steps may be continuously performed in a single reaction vessel as a series of reactions.

Further, 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- and m-tolyl isocyanate, p-formylphenyl isocyanate, p-isopropylphenyl isocyanate, 1-naphthyl isocyanate and the like can be used. The polycarbodiimide solution thus obtained is excellent in storage stability of the solution.

After the completion of the reaction, the reaction solution is poured into a poor solvent such as a lower alcohol such as methanol, ethanol or isopropyl alcohol, or a lower hydrocarbon such as hexane, heptane or pentane to precipitate polycarbodiimide as a precipitate. The monomer or catalyst may be removed. 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, by-products and unreacted substances contained in the polymer solution may be adsorbed on an appropriate adsorbent or the like and purified. As the adsorbent, for example, alumina gel, silica gel, activated carbon, zeolite, activated magnesium oxide, activated bauxite, flour earth, activated clay, molecular sieve carbon, or the like can be used alone or in combination.

The degree of polymerization n of the polycarbodiimide of the present invention is from 2 to 300, preferably from 4 to 100. If n is larger than this, it easily gels in several minutes to several hours even when left at room temperature, which is not practically preferable. On the other hand, if the molecular weight is smaller than this, the reliability of the film is lacking, which is not preferable.

(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. This 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 30 ° C. so that the curing reaction is not greatly advanced.
0 ° 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 determined according to the adherend such as a lead frame or a semiconductor chip.

In the production of the adhesive sheet, for example, aluminum, copper, silver, gold, nickel, chromium, and lead are used in order to impart conductivity, improve thermal conductivity, adjust elastic modulus, and particularly increase elastic modulus. , Tin, zinc, palladium, metals such as solder, or alloys, alumina, silica, magnesia,
One or more kinds of various inorganic powders made of ceramics such as silicon nitride and other carbon may be blended as necessary.

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 applied on the support, or a film may be formed in advance, and the film may be laminated by a press or the like.

The support used here is a metal foil,
Insulating films and the like can be mentioned. 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 or chemical resistance, such as polyimide, polyester, and polyethylene terephthalate, can be used.

The metal foil and the insulating film may be used alone, or a two-layer base material in which both layers are laminated, for example, a metal foil / insulating film 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.

(Applications) The polycarbodiimide resin thus produced can be used as an adhesive or coating material for electronic parts by utilizing its heat resistance.

[0041]

Next, the present invention will be described more specifically with reference to examples and comparative examples. All reactions were performed under a nitrogen stream. In addition, the characteristic of the obtained polycarbodiimide was measured as follows.

[0042]IR  It measured using JEOL FT / IR-230.

[0043]Thermosetting onset temperature (Tc) and glass transition temperature
Degree (Tg)  Measured using DSC-200 (manufactured by Seiko Denshi Kogyo)
The exothermic peak of trimerization was defined as the thermosetting start temperature.

[0044]Number average molecular weight (Mn)  HLC8120 (manufactured by Tosoh Corporation) as the device, GMH in the column
_HR-H+ GMH_HR-H+ G2000H_HR(Made by Tosoh Corporation)
The measurement was performed using hydrofuran as a developing solvent.

Example 1 A four-necked flask equipped with a stirrer, a dropping funnel and a reflux condenser was charged with a diamine of the following formula (IV) (13.22 g, 25.0 mmol) and triethylamine (5.06
g, 50.0 mmol) and trimethylchlorosilane (5.43 g, 5
0.0 mmol) and 72 g of toluene and stirred at 80 ° C. for 3 hours to obtain a silylated diamine.

[0046]

Embedded image

After cooling to room temperature, phenylchloroformate (7.83 g, 50.0 mmol) was put into the dropping funnel, dropped in a water bath over about 10 minutes, and stirred at room temperature overnight. After confirming the formation of carbamate by IR, trimethylchlorosilane (1.09 g, 10 mmol) and triethylamine (6.07 g, 60
mmol) and stirred at 80 ° C. for 3 hours to perform isocyanation. After confirming the formation of isocyanate by IR (FIG. 1), the mixture was cooled to room temperature and cooled to carbodiimidization catalyst (3-methyl-1-phenyl-2-phospholene-1).
-Oxide) (0.24 g, 1.25 mmol) and a terminal blocking agent (p-
Isopropylphenyl isocyanate) (0.93 g, 5.75
mmol) and polymerized at 80 ° C. for 3 hours.

The carbodiimidization was confirmed by IR spectrum (FIG. 2), and the produced triethylamine hydrochloride was removed by filtration to obtain a varnish. The number average molecular weight (Mn) of this polycarbodiimide was 2880 (n = 5). The storage stability of the varnish is 10 days or more, the varnish is cast on a glass plate, 90 ° C. for 30 minutes,
When the film was further dried at 200 ° C. for 60 minutes, a film having flexibility was obtained. The varnish was reprecipitated with isopropyl alcohol, and the precipitated solid was collected and dried. The powder obtained had Tg = 207 ° C. and Tc = 335 ° C.

Comparative Example 1 2,4-Tolylene diisocyanate / 2,6-tolylene diisocyanate mixture (mixing ratio
90:10) 5 g (28.7 mmol) together with 43 mg (0.22 mmol) of carbodiimidation catalyst (3-methyl-1-phenyl-2-phospholene-1-oxide) in 20 g of tetrahydrofuran
The mixture was stirred at ℃ for 15 hours to obtain a polycarbodiimide solution. The number average molecular weight of this polymer was 6,700 (n = 52).
The varnish was cast on a glass plate, dried at 90 ° C. for 30 minutes, and then dried at 250 ° C. for 30 minutes. The resulting film was a black, very brittle film. When the thermal properties of this film were evaluated, Tc = 300 ° C., T
g = 227 ° C.

[0050]

The polycarbodiimide of the present invention has high solubility in organic solvents, good workability, excellent heat resistance and moisture resistance, and is used as a heat-resistant coating material in a soldering step in the production of electronic parts. Can be used.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of the diisocyanate obtained in Example 1.

FIG. 2 is an infrared absorption spectrum of the polycarbodiimide obtained in Example 1.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Takami Hikita, 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Shu Mochizuki, 1-2-1, Shimohozumi, Ibaraki-shi, Osaka No. Nitto Denko F-term (reference) 4F071 AA53 AA81 AA86 AC02 AE19 AF04 AF40 AF45 AH19 BA02 BB02 BC01 4J034 AA01 HA01 HA07 HA11 HC12 HC65 HC70 HC71 KD16 KE02 LB02 LB10 QA05 QA07 QC05 QC08 HA066 4 KA23 LA07 LA08 MA02 NA19

Claims (3)

[Claims] 1. The following formula (I): (In the formula, n represents an integer of 2 to 300.) An aromatic polycarbodiimide having a structural unit represented by the following formula: 2. A polycarbodiimide solution obtained by dissolving the aromatic polycarbodiimide according to claim 1 in an organic solvent. 3. A polycarbodiimide sheet comprising the aromatic polycarbodiimide of claim 1.