JP3354285B2 - Method for producing polycarbodiimide powder or granules - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a powdery or granular polycarbodiimide from a polycarbodiimide solution.

[0002]

2. Description of the Related Art Polycarbodiimides are used as molding materials and hydrolysis stabilizers because of their heat resistance, electrical insulation, mechanical properties and reactivity. Because of its properties, it is expected that if a powder or granules of this polycarbodiimide can be efficiently produced, it will be useful in various fields.

As a conventionally known method for producing a powder or granules from a polymer solution, for example, a method in which a polymer solution is slowly added to an excess poor solvent (reprecipitation method) ) Are known and therefore there is a lot of knowledge about this method, see for example DE Roberts, J. Polym.
Sci., 2, 420 (1947), T. Alfrey, J. Polym. Sci., 3,
899 (1948), JC Berington, J. Polym. Sci., 12,
449 (1954) and the like, and “Experimental Course on Polymer Experiments 12, Purification and Chemical Reaction of Polymer Substances,
99-120, Kyoritsu Shuppan Co., Ltd. ".

Other methods other than the above include, for example, a method of selecting a solvent for synthesizing a polymer and depositing it as a powder during the synthesis, and a method of directly removing the solvent from the polymer solution and drying. It has been known.

[0005]

In the case of obtaining powders or granules from a polycarbodiimide solution, the above method can be adopted in principle. However, in the first method, polycarbodiimide is not used. , It is difficult to obtain a stable polycarbodiimide solution having a relatively high molecular weight (for example, having a degree of polymerization of 20 or more), and there are virtually no reports.

Therefore, in order to produce powder or granules from a polycarbodiimide solution, the powder or granules are produced by the second method utilizing the properties of the above polycarbodiimide. Specifically, TW Campbell, JO Chem., 28, 206
9 (1963); BJ Lyman, Macromol. Chem., 67, 1 (19
It is conceivable to use xylene, benzene, a mixed solvent of benzene / hexane, a mixed solvent of dimethylsulfoxide / chlorobenzene, or the like as a synthetic solvent to precipitate powder during the reaction as disclosed in 63).

However, when these solvents are used, powder is precipitated at an average degree of polymerization of 20 or less, and if the average degree of polymerization is increased to 20 or more, the system gels. It is difficult to obtain the above powders or granules.

Further, in order to prevent gelation of the system and obtain a polycarbodiimide powder having a low melting point which is easy to mold, a method for producing a powder whose molecular weight has been regulated by performing terminal blocking has been disclosed in Japanese Patent Application Laid-Open No. 51-61599. Gazette and J. Org. Chem., 28, 2069 (1
963) and the like.In these methods, the starting solvent is soluble as a synthesis solvent, but the high molecular weight polymer is an inert solvent which precipitates, such as benzene, toluene, xylene, decalin, chloroform, methylene chloride, It is suggested to add o-dichlorobenzene, monochlorobenzene, etc., and hexane, heptane, ligroin, methanol, etc. after powder generation for the separation of the high molecular polymer from the reaction product, or to use it in advance with a mixed solvent. However, these methods are methods of precipitating powder with an average degree of polymerization of 20 or less, and it is very difficult to obtain powders or granules with an average degree of polymerization of 20 or more.

Further, since the polycarbodiimide powder whose end is blocked contains a low molecular weight product obtained by polymerization of monoisocyanates, etc., which are end capping agents, the polycarbodiimide powder is molded or used at a high temperature of 200 ° C. or more. The low molecular weight material may be gasified and impair the intended properties, making it unusable. In actuality, when the powder is filtered from the synthesis solvent, the powder is turned into a cake (lumpy), which is then pulverized again. Without it, the desired product is often not obtained.

In the third method, it is considered that the polycarbodiimide powder can be easily obtained by removing the solvent. However, in practice, the polycarbodiimide formed in the process of removing the solvent aggregates to form a lump. It is difficult to powder.

As a method for improving these points, a method of cooling a polycarbodiimide solution to form a slurry and subjecting the slurry to spray drying has been proposed as described in Japanese Patent Application Laid-Open No. Hei 5-239223. Although this method is excellent as a method for producing fine powder, it has low productivity and is not suitable when processing capacity, that is, productivity is required instead of particle size depending on the method of use.

The present invention is based on the background of the prior art described above.
In particular, the present invention has been made to provide a method for easily producing a powder or granules from a polycarbodiimide solution using a poor solvent.

Another object of the present invention is to provide a method for easily producing a stable polycarbodiimide powder or granule having a relatively high degree of polymerization, based on the above-mentioned prior art. It is a thing.

[0014]

Means for Solving the Problems In order to achieve the above object, the present invention employs a method for producing a polycarbodiimide powder or granules which comprises stirring a polycarbodiimide solution with 100 ml of the polycarbodiimide solution at room temperature. While adding the poor solvent, the precipitation value defined as the addition amount (ml) of the poor solvent when the precipitate once formed does not re-dissolve at that time is 30 to 140. upon the polycarbodiimide powder or granules by adding a poor solvent, at least, in the step of polycarbodiimide powder or granules is deposited, a poor solvent to be added with polycarboxylic
The volume ratio with the diimide solution is approximately (precipitation value) / 100:
Within a range of 1 to (precipitation value) / 50: 1, the rate of addition of the poor solvent is 30% by volume / minute or less based on the total volume of the polycarbodiimide solution.

That is, the inventors of the present invention disclosed in Japanese Unexamined Patent Application Publication No.
As disclosed in Japanese Patent No. 92316, for example, by using an alicyclic ether as a polymerization solvent, a stable polycarbodiimide solution having an average degree of polymerization n of 20 or more can be obtained. As a result of intensive studies to obtain a powdery or granular polycarbodiimide, surprisingly, unlike the method described above,
The inventors have found that a method of adding a poor solvent to a polycarbodiimide solution is an excellent production method, and as a result of further study, the present invention has been completed.

Hereinafter, the present invention will be described in detail.

The polycarbodiimide in the polycarbodiimide solution used in the present invention includes, for example, those prepared from an organic diisocyanate in the presence of a carbodiimidization catalyst using an alicyclic ether as a polymerization solvent. As the diisocyanate, the formula (1)

Embedded image Or equation (2)

Embedded image Or equation (3)

Embedded image Can be exemplified.

In the above formulas, R ₁ , R ₂ and R ₃ are a lower alkyl group or a lower alkoxy group, R ₄ and R ₅ are a hydrogen atom, a lower alkyl group or a lower alkoxy group, and X is an oxygen atom or methylene. Since the organic diisocyanate is represented by the above formula (1), specifically, 2,4-tolylene diisocyanate, 2,6-
Tolylene diisocyanate, tolylene diisocyanate such as a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 1-methoxyphenyl-2,4-diisocyanate, and the like, and organic diisocyanate of the above formula (2) O-tolylene diisocyanate and the like; and organic diisocyanates represented by the above formula (3) as 4,4 '
-Diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, and the like. These diisocyanates may be used alone or as a mixture of two or more. Can be.

The reaction for converting the organic diisocyanate to polycarbodiimide is carried out in the presence of a carbodiimidation catalyst. Examples of the carbodiimidation catalyst include 3-methyl-1-phenyl-2-phospholene-
Examples thereof include phosphorene oxides such as 1-oxide.

The above-mentioned reaction for converting the organic diisocyanate to polycarbodiimide is carried out in an alicyclic ether as a synthesis solvent, and this alicyclic ether is preferably liquid at room temperature, It has two or less bonds. Specific examples include tetrahydrofuran, dioxane, tetrahydropyran, dioxolane, and a mixed solvent thereof. Of these, tetrahydrofuran is preferable.

When an organic diisocyanate of the type described above is used, the reaction is carried out at a monomer concentration of 30% by weight or less, preferably 20% by weight or less. When the monomer concentration is 30% by weight or more, since a large amount of isocyanate groups or low molecular weight substances are present in the resulting powder or granules, foaming occurs, such as during molding, which is not preferable. In terms of heat resistance, which is a characteristic, foaming occurs at 200 ° C. or higher, which greatly impairs desirable properties.

In order to avoid such a problem, the average degree of polymerization n of the polycarbodiimide in the polycarbodiimide solution is preferably set to 20 or more.
Basically, those without terminal sealing are preferred in terms of heat resistance.

In the present invention, for example, while stirring the polycarbodiimide solution produced as described above sufficiently quickly and uniformly, a poor solvent for the polycarbodiimide solution is added to form the polycarbodiimide into powder or granules. At least in a predetermined range of the step of depositing the polycarbodiimide powder or granules, the addition rate of the poor solvent is set to 30 to the total volume of the polycarbodiimide solution.
The term "predetermined range of the step of depositing the polycarbodiimide powder or granules" used herein refers to the type of the poor solvent, and more specifically, the deposition of the poor solvent described below. It is determined by the value.

Examples of the poor solvent for the polycarbodiimide solution include those having a deposition value of 30 to 140, preferably 40 to 100. The deposition value in the present invention is defined as: The poor solvent was added to 100 ml of the polycarbodiimide solution thus produced while stirring at around room temperature, and the amount of the poor solvent (ml ) Is defined.

When the precipitation value of the poor solvent is 30 or less, the precipitation ability becomes high, and the product becomes a lump due to rapid coagulation and precipitation. Benzene, which is usually used as a poor solvent for polycarbodiimide, because it is too poor to require a large excess of poor solvent, and in some cases, separates into two layers and produces a gel. , Chloroform, methylene chloride, xylene and the like cannot be used because the precipitation value exceeds 140.

Examples of the poor solvent include the following. That is, examples of the alicyclic hydrocarbon include cyclohexane, cyclopentane, decalin, and the like. Hexane, pentane, heptane, and the like, which are usually used in this type of reaction, have a precipitation value of 30 or less, and rapidly aggregate. As a result, the resulting product becomes a lump.

The esters include, for example, ethyl acetate, butyl acetate, methyl acetoacetate, ethyl acetoacetate, propylene glycol diacetate, and the ether esters include, for example, ethylene glycol ethyl, ether acetate, propylene glycol. Alkylene glycol ether esters such as methyl ether acetate, and further, ketones include, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, and ethers include diethyl ether. A mixture of two or more solvents having a precipitation value of 30 to 140 may be used.

The poor solvent used must be inert to the isocyanate group and the carbodiimide group. When alcohols such as methanol and ethanol are used,
Even if the deposition value is in the range of 30-140,
The system gels or the properties of the product, especially the heat resistance, are significantly impaired, and the desired product cannot be obtained.

More preferably, the poor solvent used in the present invention does not azeotrope with the synthesis solvent and has a boiling point difference of 10 ° C. or more or a boiling point of 200 ° C. or less in the step of recovering the synthesis agent.
This is advantageous in terms of the step of drying the product.

As described above, conventionally, a method of reprecipitating a polymer from a polymer solution using a poor solvent is as follows.
An excess amount of a poor solvent, particularly preferably using a poor solvent having a high precipitating ability among the poor solvents, slowly adding a polymer solution therein, to precipitate a polymer,
That is, it is added slowly to a poor solvent having an excessively high precipitating ability in order to prevent the formation of lumps due to aggregation of the polymer and to minimize the poor solvent.

Therefore, the use of a poor solvent having a low precipitating ability requires a large excess of the poor solvent and increases the burden on the subsequent steps, so that such a poor solvent was not used. Also, the poor solvent is added to the polymer solution, that is, even in the reverse addition method to the above, dissolution occurs to a certain point, and agglomeration and precipitation occur therefrom to form a lump. It was not usually performed because it was difficult to obtain as a powder.

In the present invention, when the poor solvent is added to the polycarbodiimide solution, at least in a predetermined range of the step of depositing the polycarbodiimide powder or granules, the addition rate of the poor solvent is adjusted to the total volume of the polycarbodiimide solution. However, the "predetermined range" may be determined based on the type of the poor solvent, specifically, the deposition value of the poor solvent, as described above.
For example, the volume ratio of the amount of the poor solvent to the amount of the polymer solution to be used is in the range of [precipitation value of the poor solvent to be used] / 100: 1 to [precipitation value of the poor solvent to be used] / 50: 1. Can be included.

In the above "predetermined range", the volume must be 30% by volume / min or less, preferably 20% by volume / min or less, based on the total volume of the solution. Precipitation of a high-molecular polymer occurs mainly in the inside, and the rate of addition of the poor solvent at this time governs the shape of the product.

Accordingly, if the addition rate is higher than 30% by volume / min, the product becomes a gel or a lump since the precipitation ability cannot keep up with the addition rate, and the addition rate is 30% by volume.
Min or less, but the slower the production time, the more it is usually preferable to set it to 1 vol% / min or more from this viewpoint.

As a method of addition, a normal dropping method or a method of injecting into a polymer solution may be used. The addition may be made at several places or may be added in a spray form. The addition method in which the poor solvent touches the settling vessel and runs down,
It is not preferable because a lump is formed at a portion in contact with the polymer solution.

If the amount of the liquid to be added is outside the above range, it may be added at the same rate as in the range, or the whole amount may be added at once to shorten the time.

The use amount of the poor solvent with respect to the polymer solution can be obtained even if the ratio of the polymer solution to the poor solvent exceeds 1: 5, but it is not preferable from the viewpoint of productivity.
For stirring the polycarbodiimide solution, any method used industrially can be used without any problem.

Although the production temperature when carrying out the above production method is carried out at a normal room temperature, it is obvious that the solubility is lower at a temperature lower than room temperature. If the temperature is higher, it is disadvantageous, so the temperature is preferably set to 40 ° C. or lower, more preferably 35 ° C. or lower.

The powdery or granular polycarbodiimide of the present invention thus obtained has an average particle size of about 8
Less than or equal to 00 μm, manufactured quantitatively by a simple method,
In addition, since it does not contain a low molecular compound, it does not behave like foaming in terms of properties, and any of them has a high thermal decomposition initiation temperature of 450 ° C. or more, and is used as a molding material, a modifier, etc. It has been found to be useful in a wide range of fields.

[0040]

The present invention will be described in more detail with reference to the following examples.

Production of Polycarbodiimide Solution Production Example 1 A 5-liter four-necked flask was equipped with a Dimroth condenser, a thermometer, and a mechanical stirrer, and then 4,000 ml of tetrahydrofuran was charged from the raw material introduction port. Next, 650 g of 4,4′-diphenylmethane diisocyanate (hereinafter abbreviated as MDI) as a raw material was added, and 0.2% by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide was further added to the raw material isocyanate. The reaction was carried out for 7 hours under reflux, and the average degree of polymerization was about 40 (GP
A polycarbodiimide solution having a value measured by C [hereinafter, the average polymerization indicates a value measured by this method] is obtained.

Production Example 2 The same apparatus as in Production Example 1 was charged with 4000 m of tetrahydrofuran.
Then, a mixture of 500 g of 2,4-tolylene diisocyanate as a raw material and 100 g of MDI was added, the same amount of the same catalyst as in Production Example 1 was added, the reaction was carried out under reflux for 12 hours, and the average polymerization degree was measured. A polycarbodiimide solution of No. 53 was obtained.

Production Example 3 4000 ml of dioxolan was weighed and placed in the same apparatus as in Production Example 1, then 394 g of MDI as a raw material was added, and the same amount of the same catalyst as in Production Example 1 was added. The mixture was reacted for 17 hours under reflux. Was carried out to obtain a polycarbodiimide solution having an average degree of polymerization of 37.

Production Example 4 Tetrahydrofuran 4000 m
Then, 886 g of the raw material MDI was added, and 0.1% by weight of 3 wt.
-Methyl-1-phenyl-2-phospholene-1-oxide was added, and the reaction was carried out under reflux for 6 hours to obtain a polycarbodiimide solution having an average degree of polymerization of 39.

Production Example 5 Using a 1-liter four-necked flask, assembling the same apparatus as in Production Example 1, weighing 400 ml of tetrahydrofuran and 100 ml of 1,4-dioxane, and then 50 g of o-tolidine isocyanate (TODI) as a raw material In addition, the reaction was carried out at 67 ° C. for 70 hours to obtain a polycarbodiimide solution having an average degree of polymerization of 20.

Example of Measurement of Precipitation Value The polymer solution produced in Production Example 1 was placed in an Erlenmeyer flask for 10 minutes.
0 ml was weighed out, the poor solvent was added by a burette while stirring with a magnetic stirrer, and the added amount (ml) of the poor solvent when the precipitate was not redissolved was measured as a deposition value (measurement temperature 25). ± 2 ° C). The results are shown in Table 1 below.

[Table 1]

Example 1 350 ml of the polycarbodiimide solution produced in Production Example 1
Into a three-necked flask, mechanical stirrer,
A dropping funnel and a thermometer were attached. Using butyl acetate (precipitation value 61) as a poor solvent, 700 ml was weighed into a dropping funnel. Then, 213 ml of butyl acetate was added at once while stirring the polycarbodiimide solution at room temperature (23 ° C.), and 214 ml of butyl acetate was added dropwise at a rate of 1 drop.
0% by volume / min (total volume of polycarbodiimide solution 35
(To 0 ml). Finally, the remaining 273 ml of butyl acetate was added all at once to produce a powder. This powder was filtered and dried to obtain a target powder (average particle size: 200 μm) with a yield of 80%.

Example 2 350 ml of the polycarbodiimide solution produced in Production Example 1
Was weighed into a three-necked flask, and an apparatus similar to that of Production Example 1 was assembled. 700 ml using propylene glycol methyl ether acetate (precipitation value 68) as a poor solvent
Was weighed into a dropping funnel. The polymer solution is then added to 10
The mixture was cooled to 0 ° C., stirring was started, and the dropping rate was adjusted to 1% by volume / min (based on the total volume of the polycarbodiimide solution of 350 ml), and 700 ml of the mixture was dropped. The produced powder is filtered and dried, and the desired powder (average particle size 1
00 μm) was obtained with a yield of 78%.

Example 3 350 ml of the polycarbodiimide solution produced in Production Example 2
Was weighed into a three-necked flask, and an apparatus similar to that of Production Example 1 was assembled. Using butyl acetate (precipitation value 42) as a poor solvent, 1050 ml was weighed into a dropping funnel. Next, the polymer solution was cooled to 5 ° C. and stirring was started.
ml of butyl acetate were added dropwise at once. Further, 378 ml of butyl acetate was added to the total volume of the polycarbodiimide solution (35%).
0 ml) at a rate of 3% by volume / minute, and finally the remaining 425 ml was dropped at once. The produced powder is filtered and dried, and the target powder (average particle size: 105 μm)
Was obtained with a yield of 81%.

Example 4 350 ml of the polycarbodiimide solution produced in Production Example 3
Was weighed into a three-necked flask, and an apparatus similar to that of Production Example 1 was assembled. 1050 ml using ethylene glycol ethyl ether acetate (precipitation value 80) as a poor solvent
Was weighed into a dropping funnel. Then the polymer solution is cooled
Then, stirring was started and 280 ml of ethylene glycol ethyl ether acetate was added dropwise at a time. Further, the remaining 770 ml of ethylene glycol ethyl ether acetate was added to the total volume of the polycarbodiimide solution (3.
50 ml) at a rate of 5% by volume / min.
The produced powder was filtered and dried to obtain a target powder (average particle size: 110 μm) with a yield of 81%.

Example 5 350 ml of the polycarbodiimide solution produced in Production Example 4
Was weighed into a three-necked flask, and an apparatus similar to that of Production Example 1 was assembled. Using butyl acetate (precipitation value 58) as a poor solvent, 700 ml was weighed into a dropping funnel. Next, the polymer solution was cooled to 10 ° C. and stirring was started.
ml was added at once. Wait until the temperature in the system has dropped to 10 ° C., and then add 322 ml of butyl acetate to 1% by volume / volume relative to the total volume of the polycarbodiimide solution (350 ml).
Min. Finally, the remaining 175 ml was dropped at a time, and the resulting powder was filtered and dried to obtain a target powder (average particle size: 200 μm) in a yield of 78%.

Example 6 350 ml of the polycarbodiimide solution produced in Production Example 5
Was weighed into a three-necked flask, and an apparatus similar to that of Production Example 1 was assembled. Ethyl acetate (precipitation value: 48) was used as a poor solvent, 1050 ml was weighed into a dropping funnel, stirring was started, and the temperature in the system was adjusted to 15 ° C.
The solution was dropped at a dropping rate of 20% by volume / minute (based on the total volume of the polycarbodiimide solution of 350 ml). The resulting powder is filtered and dried, and the target powder (average particle size 350 μm)
Was obtained with a yield of 83%.

Comparative Example 1 350 ml of the polycarbodiimide solution produced in Production Example 1
Was weighed into a three-necked flask, and an apparatus similar to that of Production Example 1 was assembled. Using butyl acetate (precipitation value 61) as a poor solvent, 700 ml was weighed into a dropping funnel. Then, 213 ml of butyl acetate was added dropwise at a time while stirring the polycarbodiimide solution at room temperature (23 ° C.). Further 21
4 ml of butyl acetate was added dropwise at an adjustment rate of 40 vol% / min (based on the total volume of the polycarbodiimide solution of 350 ml). Finally, the remaining 213ml
Was added dropwise at a time, and the product was filtered and dried. Most of the product was a lump, and the desired powder was obtained only in a yield of 10%.

Comparative Example 2 350 ml of the polycarbodiimide solution produced in Production Example 1
Was weighed into a three-necked flask, and an apparatus similar to that of Production Example 1 was assembled. N-Hexane as a poor solvent (precipitation value 21)
, 700 ml was measured into a dropping funnel. Next, the polymer solution was cooled to 10 ° C., and the dropping rate was 5% by volume /
Minutes (based on the total volume of the polycarbodiimide solution of 350 ml) and added dropwise, and the product was filtered and dried. The resulting product was a lump and only 7% of the desired product was obtained.

Comparative Example 3 350 ml of the polycarbodiimide solution produced in Production Example 1
Was weighed into a three-necked flask, and an apparatus similar to that of Production Example 1 was assembled. Using benzene (precipitation value of 150 or more) as a poor solvent, 1050 ml was weighed into a dropping funnel.
Next, the polymer solution was cooled to 10 ° C., and the dropping rate was 1% by volume / minute (total volume of the polycarbodiimide solution was 350 m
(relative to 1), but no product was obtained and the system remained a homogeneous solution.

Comparative Example 4 350 ml of the polycarbodiimide solution produced in Production Example 1
Was weighed into a three-necked flask, and an apparatus similar to that of Production Example 1 was assembled. Using butyl acetate (precipitation value: 61) as a poor solvent, 700 ml was weighed into a dropping funnel. Next, the polymer solution was heated to 50 ° C. using an oil bath, and 213 ml of butyl acetate was added dropwise at a time with stirring. While maintaining the temperature at 50 ° C., 214 ml of butyl acetate
Volume% / min (total volume of polycarbodiimide solution 350
(with respect to ml). Finally the remaining 27
3 ml of butyl acetate were added dropwise at one time. The system was separated from the homogeneous system by two layers, after which a precipitate was formed. The product after filtration and drying was a lump, and the target powder was only a few percent.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideji Tomita 1-1-18-1, Nishiaraimachi, Adachi-ku, Tokyo Nisshinbo Industries, Inc. Tokyo Research Center (72) Inventor Norima Nakamura 1-18, Nishiaraimachi, Adachi-ku, Tokyo -1 Inside Nisshinbo Spinning Co., Ltd. Tokyo Research Center (72) Inventor Yoji Iwasaka 1 Tohocho, Yokkaichi City, Mie Prefecture Mitsubishi Yokkaichi Plant (56) References JP-A-7-316248 (JP, A) ( 58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 3/00-3/28 C08G 18/02

Claims (7)

(57) [Claims] 1. A polycarbodiimide solution and 100 ml of the polycarbodiimide solution are stirred at room temperature.
The poor solvent is added while stirring, and the poor solvent having a precipitation value defined as the addition amount (ml) of the poor solvent when the precipitate once formed does not re-dissolve is 30 to 140. When adding the polycarbodiimide into powder or granules, at least in the step of depositing the polycarbodiimide powder or granules, the poor solvent to be added and the polycarbodiimide are added.
The volume ratio with the bodimide solution is approximately (precipitation value) / 10
Polycarbodiimide powder , wherein the addition rate of the poor solvent is 30 vol% / min or less based on the total volume of the polycarbodiimide solution within a range of 0: 1 to (precipitation value) / 50: 1. Or a method for producing granules. 2. The method for producing a polycarbodiimide powder or granule according to claim 1, wherein the polycarbodiimide is produced from an organic diisocyanate in the presence of a carbodiimidization catalyst using an alicyclic ether as a polymerization solvent. 3. The organic diisocyanate of the formula (1) Or formula (2) Or formula (3): (Wherein R ₁ , R ₂ and R ₃ represent a lower alkyl group or a lower alkoxy group, R ₄ and R ₅ represent a hydrogen atom, a lower alkyl group or a lower alkoxy group, and X represents an oxygen atom or a methylene group, respectively) The method for producing a polycarbodiimide powder or granules according to claim 1 or 2, which is an organic diisocyanate represented by the formula (1) or a mixture thereof. 4. The method for producing a polycarbodiimide powder or granules according to claim 2, wherein the alicyclic ether is tetrahydrofuran, dioxane, tetrahydropyran, dioxolan or a mixed solvent thereof. 5. The method for producing a polycarbodiimide powder or granules according to claim 1, wherein the average degree of polymerization of the polycarbodiimide in the polycarbodiimide solution is 20 or more. 6. The method for producing a polycarbodiimide powder or granules according to claim 1, wherein the ratio of the total amount of the polycarbodiimide solution to the total amount of the poor solvent is 1: 5 or less. 7. The method for producing a polycarbodiimide powder or granules according to claim 1, which is carried out at room temperature or lower.