JPH06298890A - Polycarbodiimide and production thereof - Google Patents

Abstract

PURPOSE:To obtain a polycarbodiimide composition for molding which is excellent in heat resistance and moldability by producing a polycarbodiimide comprising specific repeating units and having given terminal groups, a given mol.wt., and a given P content. CONSTITUTION:The polycarbodiimide comprises repeating units of the structure represented by the formula and has at each end a group represented by the formula -N=C=N-R1 [wherein R1 is a (lower alkyl)phenyl, a halogenated phenyl substituted with a lower alkyl, a halophenyl, a lower alkoxyphenyl, naphthyl, cyclohexyl, or a lower alkyl]. It has a weight-average mol.wt. of 20,000 or lower and a P content less than 100ppm. It is obtained preferably by polymerizing diphenylmethane 4,4'-diisocyanate with 5-25mol of an organic monoisocyanate represented by the formula R1-N=C=O per 100mol of the diisocyanate in an aromatic hydrocarbon solvent with heating in the presence of a P catalyst for carbodiimide production. The reaction mixture is cooled to precipitate a polymer, which is then slurried with a low-boiling organic solvent. This slurry is dried at a low temp. to regulate the P content of the polymer to less than 100ppm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbodiimide composition having excellent heat resistance and moldability and a method for producing the same.

[0002]

2. Description of the Related Art Generally, a high molecular weight aromatic polycarbodiimide resin is known as a resin having high heat resistance (T.
W.Campbell, KCSmeltz, J.Org.Chem., 28,2069 (196
3). However, it is difficult to dissolve in various solvents and has poor thermal fluidity, which makes practical molding difficult. J.Appl.Polm.Sci., Vol.21, 1999 [1977]
In addition, according to the description in Japanese Examined Patent Publication No. 52-16759, in order to solve the above problems, a specific ratio of diphenylmethane-4,
By reacting 4'-diisocyanate (hereinafter abbreviated as MDI) with an organic monoisocyanate as a molecular weight controlling agent in an inert organic solvent in the presence of a carbodiimide molding catalyst, it can be isolated as a powder and heated. A method for producing a polycarbodiimide that is fluid under pressure has been found.

In the former document, the above reaction is carried out in a xylene solvent, and a solid precipitated during cooling to room temperature after completion of the reaction is isolated by filtration, and one filtrate is poured into excess hexane to further precipitate. The solid is isolated by filtration,
The powder obtained by drying the combined precipitate is called molecular weight-regulated end-capped polycarbodiimide, and the properties of the polymer are described. Similarly, in Example 1 of the latter patent, the above reaction is carried out in a mixed solvent of benzene and hexane, and a solid precipitated while cooling to room temperature after completion of the reaction is isolated by filtration. The powder obtained by charging into hexane, further separating the precipitated solid by filtration, and drying the combined precipitates at 80 ° C. or higher for 4 hours is called a molecular weight-regulated end-capped polycarbodiimide. . The above references and patents make no mention of the phosphorus content in the polymer (from the use of carbodiimidated phosphorus catalysts).

By regulating the molecular weight of the polycarbodiimide obtained by this method, the solubility in a polar solvent and the fluidity under heating and pressurization were significantly improved. However, the obtained polycarbodiimide powder has a carbodiimide bond self-crosslinks and gels with heating and melting, but since this gelling rate is high, thermal fluidity stability during molding, workability is extremely poor, It wasn't practical. Further, in the same document, an attempt to further control the molecular weight to increase the fluidity is also described, but due to the decrease in the molecular weight, polycarbodiimide does not precipitate from the polymerization solvent used, so a poor solvent such as hexane was added. The complicated operation of recovering the powder is required, and the recovered powder is impractical because of impairing heat resistance.

[0005]

The object of the present invention is to improve the above-mentioned drawbacks as a thermosetting resin having a carbodiimide bond, that is, it has excellent heat resistance and can be easily isolated as a powder. It is an object of the present invention to provide a polycarbodiimide resin having excellent fluidity and thermal stability when melted, and a method for producing the same.

[0006]

Based on the above problems and problems, the present inventors have found that the phosphorus content in the polymer in the molecular weight-regulated end-capped polycarbodiimide obtained by the production methods described in the above-mentioned documents and patents ( (Derived from the use of carbodiimidated phosphorus catalyst), the phosphorus catalyst used in the production of polycarbodiimide,
For example, they have found that most of the cyclic phosphorus catalyst is present in the polymer. Furthermore, it was discovered that the higher the amount of phosphorus catalyst contained in this polymer, for example, the cyclic phosphorus catalyst, and the higher the drying temperature, the faster the gelation rate when polycarbodiimide is heated and melted.

As a result of earnest studies to solve the above-mentioned problems, polycarbodiimide obtained as a powder synthesized in an aromatic hydrocarbon solvent while controlling the molecular weight was treated with a low boiling organic solvent such as acetone. A polycarbodiimide having a phosphorus content of less than 100 ppm obtained by reslurrying and collecting by filtration and having a drying temperature of low temperature, for example, 60 ° C. or less, can meet the above purpose, that is, have excellent heat resistance. Then, they have found that they can be easily isolated as powders and have good fluidity and thermal stability when melted, and thus reached the present invention.

That is, the present invention is as follows: 1) The following formula (I)

[Chemical 4] It is composed of repeating units of

[Chemical 5] The present invention provides a polycarbodiimide composition for molding, which has a group represented by and a weight average molecular weight of 20,000 or less and a phosphorus content of less than 100 ppm. The present invention also provides diphenylmethane-4,4 '.
-100 parts by mole of diisocyanate and the following formula (III)

[Chemical 6] In the presence of a carbodiimidated phosphorus catalyst, 5 to 25 parts by mole of the organic monoisocyanate represented by is heated and polymerized in an aromatic hydrocarbon solvent, and then cooled to precipitate a polymer, and the polymer is reslurried in a low boiling point organic solvent. Then, it is dried at a low temperature to provide a method for producing the above-mentioned polycarbodiimide composition for molding, which is characterized in that the phosphorus content is less than 100 ppm.

Since the polycarbodiimide produced by the method of the present invention has an extremely low phosphorus content and a low drying temperature, when the polycarbodiimide obtained by the production method disclosed in Japanese Patent Publication No. 52-16759 of the conventional method is melted. It overcomes the disadvantage of poor flow stability of, and enables industrial implementation in which a large amount of polycarbodiimide can be produced by a simple operation. Further, the method of the present invention includes transfer molding, extrusion molding, injection molding, compression molding, etc.
This makes it possible to carry out various industrial molding methods.

The configuration will be described in detail below. Polycarbodiimide is a polymer compound having a large number of carbodiimide bonds in the molecular chain, and this compound itself is known, and can be produced from an organic polyisocyanate in the presence of a catalyst that promotes carbodiimidization of isocyanate. . For example, diphenylmethane-4,4'-diisocyanate, phenylisocyanate which is an organic monoisocyanate, and an aromatic hydrocarbon solvent are charged into a polymerization vessel. After stirring to form a uniform solution, a carbodiimidated phosphorus catalyst (3--
Methyl-1-phenyl-2-phosphorene-1-oxide etc.) is added.

The polymerization is preferably carried out at a temperature around the boiling point of the aromatic hydrocarbon solvent used, specifically about 80.
Temperatures in the range of ℃ to 150 ℃, especially about 100 ℃ to 15 ℃
It is more preferable to carry out the reaction at a temperature in the range of 0 ° C. from the viewpoint of shortening the reaction time and obtaining a polymer having a narrow molecular weight distribution. The polymerization time is preferably 1 to 6 hours. Examples of the aromatic hydrocarbon solvent for polymerization that can be used in the method of the present invention include aromatic hydrocarbon solvents such as benzene, toluene, ethylbenzene, cumene and xylene.
Considering the boiling point of the solvent and the reaction temperature, it is preferable to use toluene.

The polymer produced by the heat polymerization is cooled, for example, cooled to room temperature to be deposited, and the deposited polycarbodiimide is filtered and collected, for example, and reslurried with a low boiling point organic solvent. As the solvent used for reslurry of the obtained polymer, any solvent can be used as long as it is a solvent capable of dissolving a phosphorus compound which is a carbodiimidization-promoting solvent without dissolving the polymer, for example, a cyclic phosphorus compound. Although low-boiling organic solvents such as acetones, lower alcohols, and ethers, especially acetone, which easily volatilize at low temperature, can be used. Then, after reslurry, it is dried at a low temperature. The drying temperature is preferably 60 ° C or lower.

As the diphenylmethane-4,4'-diisocyanate (MDI) used in the method of the present invention, an industrially easily available product can be used as it is. When the purity is lowered, it is preferable to use it after distillation and purification. Alternatively, carbodiimide-modified liquid MDI may be used. When liquid MDI is used, it can be used in the same manner as MDI by examining the isocyanate content and then correcting the amount used.

In the method of the present invention, the organic monoisocyanate used as a molecular weight control agent is represented by the above chemical formula 1.
The compound of formula (III) is used. As the organic monoisocyanate, phenyl isocyanate, (ortho, meta, para) -tolyl isocyanate, dimethylphenyl isocyanate, cyclohexyl isocyanate, methyl isocyanate, butyl isocyanate, chlorophenyl isocyanate, trifluoromethylphenyl isocyanate, naphthyl isocyanate, methoxyphenyl isocyanate, Examples thereof include ethoxyphenyl isocyanate, propoxyphenyl isocyanate, and butoxyphenyl isocyanate.
It can be used in an amount of 5 to 25 parts by mol based on 100 parts by mol of the organic polyisocyanate. If the amount is less than 5 parts by mole, the degree of polymerization is too high to make it difficult to dissolve in a solvent, and the fluidity becomes poor. When it exceeds 25 parts by mole, the degree of polymerization is lowered and only polycarbodiimide having poor heat resistance can be obtained.

Various phosphorus catalysts can be used as the phosphorus catalyst for promoting the carbodiimidization of isocyanate. Preferably, a cyclic phosphorus catalyst such as a phosphorene compound can be used. As the example of the phospholene compound, one having the following formula (IV) can be used.

[Chemical 7] Furthermore, specific examples of the phosphorene compound include 1-phenyl-2-phosphorene-1-oxide and 3-methyl-1-
Phenyl-2-phosphorene-1-oxide, 1-phenyl-2-phosphorene-1-sulfide, 1-ethyl-2
Preference is given to -phospholen-1-oxide, 1-ethyl-3-methyl-2-phospholen-1-oxide, their corresponding isomers, 3-phosphorenes. The catalyst amount is usually 0.01-1% based on the total amount of isocyanate.

According to the method of the present invention, for example, the phosphorus content is less than 100 ppm, the weight average molecular weight is about 3,000 to about 20,000, the melting point is about 130 ° -150 ° C., and 5% of the polymer is used. The thermal decomposition temperature is about 530 ° C. or higher, and polycarbodiimide suitable for carrying out various industrial molding methods such as transfer molding, extrusion molding, injection molding and compression molding can be obtained.

[0017]

EXAMPLES Next, examples of the present invention will be shown and described more specifically. However, the present invention is not limited to these examples. Further, the analysis and physical property values of the polymers obtained in Examples and Comparative Examples were measured by the following methods.

Average molecular weight and molecular weight distribution: The polymer powder was dissolved with N-methylpyrrolidone and using GPC,
The curve of the molecular weight distribution curve was measured, and the polymerization average molecular weight and the molecular weight distribution were obtained using polystyrene and a standard. Phosphorus content: Quantified by micro phosphorus analysis (molybdenum blue method). Melting point: The melting point of the polymer was measured in nitrogen at a temperature rising rate of 16 ° C./min using a main differential scanning calorimeter (DSC). 5% decomposition temperature: A 5% weight loss temperature of the polymer was measured at a temperature rising rate of 10 ° C./min in air using a thermogravimetric analyzer (TGA). Melt viscosity: 100kg after preheating at a temperature of 150 ° C for a predetermined time using a Koka type flow tester (manufactured by Shimadzu Corporation)
It was measured by applying a load of f / cm ² . Gel time: 0.5g polymer on hot plate (150 ℃)
Was melted with a metallic spatula and continuously stirred, and the time when the resin became more viscous and the string was no longer drawn was taken as the gel time. Gel time change rate: After polycarbodiimide was separated by filtration,
The rate of change between the gel time (T0) of a sample air-dried at room temperature (27 ° C.) under a nitrogen stream and the gel time (T1) of a sample dried at a predetermined temperature for a predetermined time was defined as a gel time change rate (Gr). Gr = [(T0-T1) / T0] × 100 The gel time change rate is preferably 30% or less in terms of molding.

Example 1 Diphenylmethane-4,4'-in a 500 ml separable flask equipped with a stirrer, thermometer and cooling condenser.
Diisocyanate (MDI) 60.62 g (0.242
Mol), phenylisocyanate (PhI) 3.17 g
(0.0266 mol, molar ratio MDI / PhI = 9.1
1), charge 128 ml of dry toluene in a nitrogen atmosphere,
It was uniformly dissolved with stirring. Next, 3-methyl-1-
Phenyl-2-phosphorene-1-oxide catalyst 0.02
Toluene solution 0.5 containing 3 g (0.00012 mol)
ml was added, and the internal temperature was raised to 110 ° C. with stirring. The generation of carbon dioxide increased with increasing temperature, and particularly intense generation of carbon dioxide was observed when the internal temperature exceeded 100 ° C. Polymerization was carried out for 6.0 hours after the internal temperature reached 110 ° C. After the polymerization was completed, a white polymer was precipitated from the toluene solution while cooling to room temperature. The precipitate was filtered off, reslurried with 150 ml of acetone for 30 minutes, and filtered again to isolate. The isolated precipitate was dried overnight under a nitrogen stream and then dried at 60 ° C. for 12 hours to obtain a white powdery polycarbodiimide.

The analysis and physical properties of this polymer were as follows. Yield (%) 94 Average molecular weight (Mw) 8400 Molecular weight distribution (Mw / Mn) 2.0 Phosphorus content (ppm) 25 Melting point (° C) 138 5% Decomposition temperature (° C) 543 Melt viscosity (poise) Preheating 3 minutes 750 Gel time at 150 ° C. (sec) 280 Gel time change rate (%) 9.0

Example 2 Diphenylmethane-4,4'-in a 500 ml separable flask equipped with a stirrer, thermometer and cooling condenser.
Diisocyanate (MDI) 46.79 g (0.187
Mol), phenyl isocyanate (PhI) 2.80 g
(0.0235 mol, molar ratio MDI / PhI = 7.9
7), charge 100 ml of dry toluene into a nitrogen atmosphere,
It was uniformly dissolved with stirring. Next, 3-methyl-1-
Phenyl-2-phosphorene-1-oxide catalyst 0.01
0.4 ml of a toluene solution containing 80 g (0.000094 mol) was added, and the internal temperature was raised to 110 ° C while stirring. The generation of carbon dioxide increased with increasing temperature, and particularly intense generation of carbon dioxide was observed when the internal temperature exceeded 100 ° C. After the internal temperature reaches 110 ° C, 6.
It was polymerized for 0 hours. After the polymerization was completed, a white polymer was precipitated from the toluene solution while cooling to room temperature. The precipitate was filtered off, reslurried with 150 ml of acetone for 30 minutes, and filtered again to isolate. The isolated precipitate was dried overnight under a nitrogen stream and then dried at 60 ° C. for 12 hours to obtain a white powdery polycarbodiimide.

The analysis and physical properties of this polymer were as follows. Yield (%) 92 Average molecular weight (Mw) 7300 Molecular weight distribution (Mw / Mn) 1.9 Phosphorus content (ppm) 15 Melting point (° C) 136 5% Decomposition temperature (° C) 539 Melt viscosity (poise) Preheating 3 minutes 457 Gel time at 150 ° C. (second) 322 Gel time change rate (%) 8.5

Comparative Example After completion of the polymerization, instead of reslurrying the precipitated polymer, the polymer separated by filtration and the filtrate are put into excess hexane, and the polymer precipitated and collected by filtration is combined and dried at 80 ° C. for 6 hours. Polymerization was performed by the same method as in Example 1 except for the above, to obtain a white powdery polycarbodiimide.

The analysis and physical properties of this polymer were as follows. Yield (%) 97 Average molecular weight (Mw) 8000 Molecular weight distribution (Mw / Mn) 2.2 Phosphorus content (ppm) 515 Melting point (° C) 135 5% Decomposition temperature (° C) 529 Melt viscosity (poise) Preheating 3 minutes 2750 Gel time at 150 ° C. (sec) 105 Gel time change rate (%) 63

[0025]

The polycarbodiimide produced by the method of the present invention has excellent heat resistance, has an extremely low phosphorus content, and is dried at a low temperature, for example, 60 ° C. or lower. Overcoming the disadvantage that the flow stability of polycarbodiimide when melted is poor, it enabled industrial implementation that polycarbodiimide can be produced in large quantities by a simple operation, low gel time change rate, for example The industrial utility value is extremely high, such as 30% or less.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiro Yamaguchi 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Toatsu Chemical Co., Ltd.

Claims (5)

[Claims] 1. The following formula (I): It is composed of repeating units of and has the following formula (II) at both ends: A polycarbodiimide composition for molding which has a group represented by the formula (1) and has a weight average molecular weight of 20,000 or less and a phosphorus content of less than 100 ppm. 2. 100 parts by mol of diphenylmethane-4,4'-diisocyanate and the following formula (III): In the presence of a carbodiimidated phosphorus catalyst, 5 to 25 parts by mole of the organic monoisocyanate represented by is heat-polymerized in an aromatic hydrocarbon solvent and then cooled to precipitate a polymer, and the polymer is reslurried in a low-boiling organic solvent. After that, it is dried at a low temperature to make the phosphorus content less than 100 ppm, and the method for producing the polycarbodiimide composition for molding according to claim 1. 3. The method according to claim 2, wherein the aromatic hydrocarbon solvent is a member selected from the group consisting of benzene, toluene, ethylbenzene, cumene and xylene. 4. The method according to claim 2, wherein the low boiling point organic solvent is a member selected from the group consisting of acetones, lower alcohols, and ethers. 5. The manufacturing method according to claim 2, wherein the drying temperature is 60 ° C. or lower.