JP3335270B2 - Method for producing polycarbodiimide resin powder - 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 polycarbodiimide resin powder, and more particularly to a method for producing a polycarbodiimide resin powder by allowing a polymerization reaction to proceed and then cooling it to form a slurry. And a method for producing a polycarbodiimide resin powder.

[0002]

2. Description of the Related Art A polycarbodiimide resin is a polymer compound having a repeating unit of the formula -N = C = NR-. This polycarbodiimide resin is excellent in heat resistance and the like.
Conventionally, it has been used for various uses such as molding materials, resin modifiers and adhesives.

[0003] However, polycarbodiimide resins, particularly aromatic polycarbodiimide resins, which are particularly advantageous in terms of heat resistance and chemical resistance, are difficult to dissolve in various solvents, and when the molecular weight is increased, the reaction system gels. Difficult to obtain powder. For example, the prior art for producing powders includes TW Campbell et al., J. Org. Chem., 28 , 2069 (19
63) CS Fold et al., Macromol. Syn., 1 , 74 (1963) TW Campbell et al., Macromol. Syn., 3 , 109 (1963)
9) and the like, and these prior arts include producing a polycarbodiimide resin powder using a single or mixed solvent in which the raw material diisocyanate is dissolved and the generated polycarbodiimide resin is not dissolved. .

[0004] However, the polycarbodiimide resin powder obtained by precipitation according to the above-mentioned prior art has a relatively low molecular weight and therefore has a large amount of residual isocyanate groups.
When handled at a temperature of 180 ° C. or higher, it becomes a molten state, the carbodiimidization reaction proceeds again, and foaming and swelling occur due to decarboxylation reaction, which becomes a problem when used as a molding material, a modifier, for example. I have.

[0005] Further, in the above-mentioned prior art, there is also a knowledge of a relatively high molecular weight polycarbodiimide resin, but gelation occurs during the reaction, and this gel is pulverized and desolvated in a poor solvent to obtain a powder. Although it is possible to experimentally produce the method, it is not practical to employ a step of pulverizing and desolvating the gel or to use an excess amount of the poor solvent with respect to the gel because of poor efficiency.

In order to improve these problems, J. Appl.
olym. Sci., 21 , 1999 (1977), JP-B-52-1675
No. 9, JP-A-5-239223, and the like.
A method for isolating a polycarbodiimide resin as a powder by reacting 4'-diphenylmethane diisocyanate with an organic monoisocyanate as a molecular weight regulator in an inert organic solvent in the presence of a carbodiimidization catalyst is disclosed. .

That is, the above reaction is carried out in the above-mentioned J. Appl. Polym. Sci. In a xylene solvent, and after cooling to room temperature after the completion of the reaction, a solid that precipitates is isolated by filtration. Of hexane, and further, the precipitated solid is isolated by filtration, and the powder obtained by drying the combined precipitate is called an end-blocked polycarbodiimide, and its properties are described. .

Further, Japanese Patent Publication No. 52-16759 is the same as described above except that a mixed solvent of benzene / hexane is used as a synthesis solvent as shown in Example 1.

Further, Japanese Patent Application Laid-Open No. Hei 5-239223 discloses that the above-mentioned carbodiimidization reaction is carried out using a halogen-based solvent as a synthesis solvent to form a uniform polycarbodiimide resin solution, which is then cooled to form a slurry. A method for obtaining a powder having a narrow particle size distribution by spray drying is described.

That is, these technologies are characterized in that a gel is prevented by regulating the molecular weight by using a terminal blocking agent, and a solid is precipitated by utilizing the solubility of the polycarbodiimide resin in a solvent to form a powder. To get.

[0011]

However, since the terminal-blocking polycarbodiimide resin powder thus obtained uses an organic monoisocyanate as a terminal-blocking agent, a reaction between the terminal-blocking agents occurs and monocarbodiimide is produced. And low molecular weight carbodiimides are generated, depending on the application, decomposition and gasification of these occur, foaming, swelling,
May cause odor and cause problems.

When used in a medium such as oil,
The medium may be altered due to elution of low molecular weight substances into the medium and the like, and generally used organic monoisocyanates are expensive, and the use thereof increases the cost.

An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a method for easily producing a polycarbodiimide resin powder having a relatively high molecular weight without using a terminal blocking agent. It was made as.

[0014]

To achieve the above object, the present invention employs a method for producing a polycarbodiimide powder, which comprises producing a polycarbodiimide resin from an organic diisocyanate in a solvent in the presence of a polycarbodiimidization catalyst. And producing the resulting polycarbodiimide resin as a powder, wherein the organic diisocyanate is represented by the formula

Embedded image Or

Embedded image (Wherein, R ₁ represents a lower alkyl group or a lower alkoxy group) or

Embedded image Wherein R ₂ and R ₃ represent a hydrogen atom, a lower alkyl group or a lower alkoxy group, and X represents an oxygen atom or a methylene group, respectively.

Embedded image (Wherein R ₄ and R ₅ represent a hydrogen atom, a lower alkyl group or a lower alkoxy group), a good solvent for the polycarbodiimide resin as the solvent, and a precipitation value of 30 to 80. By using a mixed solvent with a poor solvent, by allowing the polymerization reaction to proceed and then cooling,
The polycarbodiimide resin is slurried to obtain a powder.

Hereinafter, the present invention will be described in detail.

The organic diisocyanate used in the present invention, as represented by the above formula, has crystallinity when polycarbodiimidized. Specifically, such organic diisocyanates include: For example, 4,4′-diphenylmethane diisocyanate,
4'-diphenyl ether diisocyanate, p-phenylene diisocyanate, 3,3'-dimethoxy-4,
4'-biphenyl diisocyanate, o-tolidine diisocyanate and the like can be mentioned.

In the present invention, an organic diisocyanate other than the above may be mixed with the organic diisocyanate. For example, as the organic diisocyanate to be mixed with the above 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate is particularly preferred. Can be exemplified.

As the carbodiimidization catalyst, a conventionally known catalyst may be used. For example, 3-methyl-1-phenyl-2-phospholene-1-oxide,
Phosphorene oxides such as -methyl-1-phenyl-3-phospholene-1-oxide, 3-methyl-1-ethyl-2-phospholene-1-oxide can be used,
Among them, 3-methyl-1-phenyl-2-phospholene-1
-Oxides are preferred in terms of reactivity.

In the present invention, the synthesis of the polycarbodiimide resin in the presence of the carbodiimidization catalyst needs to be performed with a mixed solvent of a good solvent of the polycarbodiimide resin and a poor solvent having a deposition value of 30 to 80. is there.

The good solvent used in the present invention is preferably an alicyclic ether which is liquid at room temperature, and examples thereof include tetrahydrofuran, dioxane, tetrahydropyran, and dioxolan. Is preferably tetrahydrofuran.

Further, as the poor solvent, the precipitation value is 30 to 8
It must be of the order of 0, preferably 40 to 60, and this concept of "precipitation value" used in the present invention is defined as follows. Precipitation value Polycarbodiimide resin solution having a molecular weight of 7000 to 9000 synthesized in tetrahydrofuran solution using 4,4′-diphenylmethane diisocyanate as an organic diisocyanate and a monomer concentration of 15% by weight
The poor solvent was added to 00 ml with stirring at 25 ± 2 ° C., and the amount of the poor solvent added when the precipitate once formed was no longer redissolved (ml).

Examples of the poor solvent having a precipitation value of 30 to 80 include the following. That is, cyclohexane, cyclopentane, decahydronaphthalene and the like as alicyclic hydrocarbons, and methyl acetate, ethyl acetate, ethyl acetoacetate, butyl acetate, methyl lactate, ethyl lactate, isopropyl lactate as esters. Ethylene glycol diacetate, etc., ethers such as diethyl ether, dibutyl ether, isopropyl ether, etc .; ether esters, such as propylene glycol methyl ether acetate; ketones, such as acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, Methyl isobutyl ketone, methyl isopropyl ketone and the like,
These solvents can be used as a mixture of two or more kinds.

Hexane, pentane and the like, which are generally known as poor solvents for polycarbodiimide resins, have a precipitation value of less than 30. If these are used as poor solvents, the reaction system will be separated into two layers during the reaction. Alternatively, precipitation occurs, and the desired product cannot be obtained.

When a solvent having a precipitation value exceeding 80, for example, benzene, toluene, methylene chloride, chloroform, chlorobenzene, dimethylacetamide or the like is used, the reaction system is gelled, and the desired product cannot be obtained.

The composition ratio of these good solvent and poor solvent is such that good solvent / poor solvent ≦ 150 / precipitation value, and preferably good solvent / poor solvent amount ≦ 100 / precipitation value.

In the production method of the present invention, the monomer concentration of the above-mentioned organic diisocyanate as a raw material is
An example is a range of 40% by weight or less, preferably 15 to 35% by weight.

The reaction temperature in the production method of the present invention is determined by the type of the mixed solvent. When the mixed solvent azeotropes, the reaction temperature is the azeotropic point, and when the mixed solvent has a boiling point difference, the reaction temperature is between the boiling points of the respective solvents. The reaction time is determined depending on the reaction temperature, but is about several hours to about several tens hours.

For example, at a monomer concentration of 35% by weight, a mixed solvent of tetrahydrofuran / ethyl acetate = 1.2 /
The reaction temperature is 70 ° C., the reaction time is 3 hours when the ratio is 1 (volume ratio), the monomer concentration is 20% by weight, and the mixed solvent is tetrahydrofuran / acetone = 1.5 / 1 (volume ratio). Is 60 ° C. and the reaction time is 5 hours.

In the prior art, when a reaction is carried out in a homogeneous system in order to obtain a high molecular weight polycarbodiimide resin, gelation occurs, or the polycarbodiimide resin precipitates before reaching a target molecular weight, and the polymerization is stopped. However, in the present invention, a high-molecular-weight polycarbodiimide resin can be produced at a high concentration without gelation. The number average molecular weight can be, for example, 7000 or more in terms of styrene measured by GPC (gel permeation chromatography).

In the present invention, as described above, it is not clear that a high-molecular-weight polycarbodiimide resin can be produced at a high concentration without gelation, but it is considered as follows. That is, when the molecular weight reaches a certain level in the polymerization process, the local concentration of the polycarbodiimide resin increases, and as a result, for example, a two-liquid layer system of a layer having a high polymer concentration and a layer having a low polymer concentration is formed. It becomes a microgel or an aggregate similar thereto (this state is referred to as microphase separation in this specification). When the polymerization reaction proceeds further in this state, a high-molecular-weight polycarbodiimide resin can be produced at a high concentration without causing gelation.

When the system is further heated, the state of the microphase separation or the like or the state of the microgel or the like shifts to a macro state, respectively, leading to gelation. However, in the present invention, the system is changed before shifting to the macro state. By cooling, agglomeration and crystallization proceed in a micro state, and slurry is obtained to obtain a powder. The cooling condition at this time is a cooling temperature of room temperature or less, preferably 10 ° C. or less. It is necessary to continue stirring until the reaction is completed. The particle size of the polycarbodiimide resin powder can be controlled to some extent by the cooling rate and stirring conditions at this time.

In the cooling timing, particles or the like having a diameter within a visible range are generated in the initial stage when the state of the micro phase separation or the like or the state of the micro gel or the like shifts to a macro state, and therefore, the reaction system becomes white. This can be confirmed by visual observation, so that cooling can be started at this time, or the reaction system can be periodically sampled, and the molecular weight of this sample can be determined by GPC.
And a desired molecular weight (for example, 3 in number average molecular weight).
The cooling may be started at the point of time when the growth reaches 000 or more, preferably 4500 or more). The number average molecular weight is 3000
If it is smaller, foaming and swelling occur as described above, which is not preferable.

The cooling timing is determined by NCO% or IR
It can also be determined by the transmittance ratio of the isocyanate group and the carbodiimide group in the spectrum, and the former is 3 or less, preferably 2.5 or less, and the latter is 4 or more, preferably 5 or more. The timing of the start is the timing of the start of cooling.

For the production of the polycarbodiimide resin powder from the slurry, a known method can be adopted, for example, a method of performing filtration, drying or spray drying.
It is easily presumed that by applying the production method of the present invention, an end-capped polycarbodiimide resin powder can also be produced.

When a solvent having a boiling point close to that of a good solvent and a poor solvent is selected, a mixed solvent of the good solvent and the poor solvent can be recovered from the polycarbodiimide resin slurry and reused as it is. Examples of suitable solvent combinations include tetrahydrofuran (good solvent) and ethyl acetate (poor solvent).

[0036]

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

Example 1 Synthesis of Slurry A synthetic apparatus equipped with a Dimroth condenser, a thermometer, and a mechanical stirrer was prepared in a three-liter four-necked flask, and 600 ml of tetrahydrofuran and 500 ml of ethyl acetate were charged from the raw material inlet. Then, the raw material 4,4'-diphenylmethane diisocyanate (hereinafter, referred to as
530 g was added, and the mixture was stirred and heated.
When the temperature in the system reached 50 ° C., 0.2% by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide based on the raw material isocyanate was added, and then about 2.5% under reflux. A time reaction was performed. At this time, when the molecular weight of the polycarbodiimide resin was measured by GPC, the number average molecular weight was 5,300. Next, the reaction system was cooled, and the temperature in the system was lowered to 5 ° C. after 1 hour, and the temperature was maintained for 5 hours. White turbidity started around the time when the temperature in the system became 20 ° C., and finally a slurry was formed. The number average molecular weight of the polycarbodiimide resin immediately after forming the slurry is 7
000.

Production of Powder The slurry obtained by the above synthesis was filtered under reduced pressure using a Nutsche to obtain a wet cake. This is gently melted with a mortar, and further dried at 70 ° C. for 5 hours by vacuum drying.
A white powder was obtained.

Example 2 Synthesis of Slurry Using the same synthesis apparatus as in Example 1, 600 ml of tetrahydrofuran and 660 ml of ethyl acetate were charged from the raw material inlet. Next, 610 g of MDI was added, and the mixture was stirred and heated. When the temperature in the system reached 50 ° C., 0.2% by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide with respect to the starting isocyanate was added, and then about 2.8 under reflux. When the reaction was carried out for a period of time, whitening of the system was slightly observed, and thus cooling was performed in the same manner as in Example 1. Although the inside of the system was slightly white, it gradually returned to transparent as it cooled, and began to become cloudy at around 20 ° C. in the same manner as in Example 1, and finally formed a slurry. The number average molecular weight of the polycarbodiimide resin immediately after the formation of the slurry was 9,800.

Production of Powder The slurry obtained by the above synthesis was put into a spray dryer at a drying temperature of 100 ° C. to obtain a white powder.

Example 3 Using the same synthesizing apparatus as in Example 1, 600 ml of tetrahydrofuran and 500 ml of ethyl acetate were charged from the raw material inlet. Next, 170 g of MDI was added, followed by stirring and heating. When the temperature in the system reached 50 ° C., 0.2% by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide based on the raw material isocyanate was added, and then the reaction was performed under reflux for about 6 hours. Was done. At this time, when the molecular weight of the polycarbodiimide resin was measured by GPC, the number average molecular weight was 5,800. Next, cooling was performed in the same manner as in Example 1. The inside of the system was the same as in Example 1, and a slurry was formed. The number average molecular weight of the polycarbodiimide resin immediately after the formation of the slurry was 7,800.
Powdering was performed in the same manner as in Example 1 to obtain a white powder.

Example 4 Using the same synthesis apparatus as in Example 1, 1000 ml of tetrahydrofuran and 400
ml. Then add 510 g of MDI,
Stir and heat. When the temperature in the system reached 50 ° C., 0.2% by weight of 3-methyl-
1-Phenyl-2-phospholene-1-oxide was added, and the reaction was performed under reflux for about 3 hours. At this time, when the molecular weight of the polycarbodiimide resin was measured by GPC, the number average molecular weight was 5,100. Next, cooling was performed in the same manner as in Example 1. The inside of the system was the same as in Example 1, and a slurry was formed. The number average molecular weight of the polycarbodiimide resin immediately after the formation of the slurry was 7,000. Powdering was performed in the same manner as in Example 1 to obtain a white powder.

Example 5 Using the same synthesizing apparatus as in Example 1, 900 ml of tetrahydrofuran and 300 ml of diisopropyl ether were respectively charged from the raw material inlet. Next, 440 g of MDI was added, and the mixture was stirred and heated. When the temperature in the system reached 50 ° C., 0.2% by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide with respect to the raw material isocyanate was added, and then the reaction was performed under reflux for about 3 hours. Was done. At this point, the molecular weight of the polycarbodiimide resin is
When measured by C, the number average molecular weight was 5,200. Next, cooling was performed in the same manner as in Example 1. The inside of the system was the same as in Example 1, and a slurry was formed. The number average molecular weight of the polycarbodiimide resin immediately after forming the slurry is 7
It was 100. Powdering was performed in the same manner as in Example 1 to obtain a white powder.

Example 6 Using the same synthesizing apparatus as in Example 1, 600 ml of tetrahydrofuran and 500 ml of ethyl acetate were charged from the raw material inlet. Then, 330 g of o-tolidine diisocyanate (TODI) was added, and the mixture was stirred and heated. When the temperature in the system reached 50 ° C., 0.2% by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide with respect to the raw material isocyanate was added, and then the reaction was performed under reflux for about 5 hours. Was done. At this time, when the molecular weight of the polycarbodiimide resin was measured by GPC, the number average molecular weight was 4,500. Next, cooling was performed in the same manner as in Example 1. The inside of the system was the same as in Example 1 to form a slurry. The number average molecular weight of the polycarbodiimide resin immediately after forming the slurry was 6,100.

Comparative Example 1 Using the same synthesis apparatus as in Example 1, 1000 ml of tetrahydrofuran was charged from the raw material inlet. Then MDI4
50 g was added, and the mixture was stirred and heated. When the temperature in the system reaches 50 ° C., 0.2% by weight based on the raw material isocyanate
Of 3-methyl-1-phenyl-2-phospholene-1-oxide was added, and then the reaction was carried out under reflux for about 3 hours, at which point the system gelled, and a slurry could not be obtained. .

The above gel was put into a mixer together with 2 l of hexane and stirred. These were filtered, further washed with hexane, and vacuum dried at 70 ° C. for 5 hours to obtain a fibrous mass.

Comparative Example 2 Using the same synthesis apparatus as in Example 1, 1000 ml of ethyl acetate was charged from the raw material inlet. Next, 480 g of MDI was added, and the mixture was stirred and heated. When the temperature in the system reached 50 ° C., 0.2% by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide with respect to the raw material isocyanate was added, followed by a reaction under reflux for about 30 minutes. At the time of performing, a lump in the system was generated, and a slurry could not be obtained.

The mass was separated by filtration,
It was vacuum-dried for 5 hours and pulverized by a pulverizer to obtain a powder.

Comparative Example 3 Using the same synthesis apparatus as in Example 1, 600 ml of tetrahydrofuran and 500 ml of hexane were charged from the raw material inlet. Next, 460 g of MDI was added, and the mixture was stirred and heated. When the temperature in the system reached 50 ° C., 0.2% by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide based on the raw material isocyanate was added, and then the reaction was performed under reflux for about 50 minutes. Was performed, the mixture was separated into two layers. Thereafter, a lump of polycarbodiimide resin was formed, and a slurry could not be obtained. A powdery substance was obtained from the formed lump by the same operation as in Comparative Example 2.

Comparative Example 4 Using the same synthesis apparatus as in Example 1, 600 ml of tetrahydrofuran and 500 ml of toluene were charged from the raw material inlet. Next, 520 g of MDI was added, and the mixture was stirred and heated. When the temperature in the system reached 50 ° C., 0.2% by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide with respect to the raw material isocyanate was added, and then about 1.5% under reflux. At the point of time when the reaction was carried out, the inside of the system was gelled, and a slurry could not be obtained. The produced gel was obtained in the same manner as in Comparative Example 1 to obtain a powder.

Comparative Example 5 Using the same synthesis apparatus as in Example 1, 1000 ml of benzene and 190 ml of hexane were charged from the raw material inlet. Next, 360 g of MDI and 34.3 g of phenyl isocyanate were added, respectively, and the mixture was stirred and heated.
When the temperature in the system reached 50 ° C., 0.2% by weight of 3-methyl-1-phenyl-2-phospholene-1-oxide with respect to the raw material isocyanate was added, followed by a reaction at 70 ° C. for 3 hours. A theoretical amount of carbon dioxide was captured. In the reaction system, formation of precipitates has begun, and the system was left in this state for another 16 hours. The system in which the precipitate was formed and turned cloudy was cooled to room temperature (about 20 ° C.), the precipitate was filtered, the filtrate was poured into excess hexane, a precipitate was further obtained, and the precipitate was filtered. Both precipitates were combined, dried in air overnight, and then dried in vacuum at 80 ° C. for 4 hours to obtain an end-capped polycarbodiimide resin having an average degree of polymerization of n = 10.

Reference Experiment Thermal evaluation of the powders obtained in Examples 1 to 6 and Comparative Examples 1 to 5 was performed as follows. The results were as shown in Table 1. Weight loss rate by thermal analysis (TG) TG measurement condition: Heating rate 20 ° C / min Final temperature 800 ° C Evaluation method: Weight loss rate at 300 ° C by TG curve Thermal behavior of molded film Molding condition: Sample amount 2g Molding Temperature 160 ° C Molding time 10 minutes Molding total pressure 1000 kg Evaluation method: A film-like material molded under the above conditions was placed on a 260 ° C board for 10 minutes, and the presence or absence of foaming was observed.

[0053]

[Table 1]

[0054]

The method for producing a polycarbodiimide resin powder according to the present invention is a method for producing a polycarbodiimide resin as a powder by generating a polycarbodiimide resin from an organic diisocyanate in a solvent in the presence of a polycarbodiimidization catalyst. As the organic diisocyanate, one having crystallinity when polycarbodiimidized is used, and as the solvent, a mixed solvent of a good solvent for the polycarbodiimide resin and a poor solvent having a deposition value of 30 to 80 is used. The polycarbodiimide resin is slurried by cooling after the polymerization reaction is allowed to proceed, and is obtained as a powder. A polycarbodiimide resin powder having a relatively high molecular weight can be easily produced without using a terminal blocking agent. can do.

The polycarbodiimide resin powder obtained by the production method of the present invention is excellent in that the weight loss at high temperatures is extremely small, and that no foaming occurs when formed into a film.

──────────────────────────────────────────────────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 Nisshinbo Industries, Inc. Tokyo Research Center Examiner Masahiro Shibata (56) References JP-A-7-316248 (JP, A) JP-A-7-330913 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) C08G 18/00-18/02 C08G 18/08-18/09

Claims (8)

(57) [Claims] 1. A method for producing a polycarbodiimide resin from an organic diisocyanate in a solvent in the presence of a polycarbodiimidization catalyst and obtaining the produced polycarbodiimide resin as a powder, wherein the organic diisocyanate has the formula: Or (Wherein, R ₁ represents a lower alkyl group or a lower alkoxy group) or (Wherein R ₂ and R ₃ represent a hydrogen atom, a lower alkyl group or a lower alkoxy group, and X represents an oxygen atom or a methylene group, respectively) or (Wherein R ₄ and R ₅ represent a hydrogen atom, a lower alkyl group or a lower alkoxy group), a good solvent for the polycarbodiimide resin as the solvent, and a precipitation value of 30 to 80. By using a mixed solvent with a poor solvent, by allowing the polymerization reaction to proceed and then cooling,
A method for producing a polycarbodiimide resin powder, which comprises slurrying a polycarbodiimide resin to obtain a powder. 2. The method for producing a polycarbodiimide resin powder according to claim 1, wherein the good solvent of the polycarbodiimide resin is an alicyclic ether. 3. The method for producing a polycarbodiimide resin powder according to claim 2, wherein the good solvent of the polycarbodiimide resin is tetrahydrofuran. 4. The polycarbodiimide according to claim 1, wherein the mixing ratio of the good solvent and the poor solvent in the mixed solvent of the good solvent and the poor solvent with respect to the polycarbodiimide resin is good solvent / poor solvent amount ≦ 150 / precipitation value. Method for producing resin powder. 5. The method for producing a polycarbodiimide resin powder according to claim 1, wherein the reaction is carried out at a monomer concentration of the organic diisocyanate of 40% by weight or less. 6. The polycarbodiimide resin powder according to claim 1, wherein a solvent having a boiling point close to that of the good solvent and the poor solvent is selected, and a mixed solvent of the good solvent and the poor solvent is recovered from the slurry of the polycarbodiimide resin. Production method. 7. The method for producing a polycarbodiimide resin powder according to claim 6, wherein the good solvent is tetrahydrofuran and the poor solvent is ethyl acetate. 8. The method for producing a polycarbodiimide resin powder according to claim 1, wherein cooling is started when the polycarbodiimide resin reaches a desired molecular weight.