JP2011190352A - Method for producing granular resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for collecting a resin dissolved in a good solvent as a granular resin with good handleability, while suppressing adhesion among the resins. <P>SOLUTION: The method for producing the granular resin comprises: a step of depositing the granular resin in a dispersion liquid by dropping the resin solution containing the resin and the good solvent, in which the resin is dissolved, into the dispersion liquid containing a poor solvent of the resin and a filler; and a step of collecting the granular resin from the dispersion liquid. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a granular resin.

  The resin synthesized in a good solvent can be separated and recovered from the good solvent by a reprecipitation technique.

  In the reprecipitation technique, for example, a resin solution in which a resin is dissolved in a good solvent is added to a stirred poor solvent, and the precipitated resin is separated from the solvent and collected. Patent Document 1 discloses a method in which a resin solution in which a resin is dissolved in a good solvent is placed in vigorously stirred water, and the deposited precipitate is filtered and dried to obtain a resin simple substance.

JP 2005-220339 A

  However, in the conventional method as disclosed in Patent Document 1, the deposited resins tend to adhere to each other and form a large lump. A resin that forms a large lump is difficult to separate from a good solvent, or takes a long time to dry.

  Further, in the case of a resin having a low glass transition temperature, even if it can be recovered in a granular state, if it is heated too much during drying, the resin melts to form a large lump, and the subsequent handleability may be impaired. .

  Then, the objective of this invention is providing the method of collect | recovering resin melt | dissolved in the good solvent as granular resin with favorable handleability, suppressing adhesion of resin.

  The present invention includes a step of dropping a resin solution containing a resin and a good solvent in which the resin is dissolved into a dispersion containing a resin poor solvent and a filler to precipitate a granular resin in the dispersion. And a step of recovering the granular resin from the dispersion, and a method for producing the granular resin.

  According to the production method of the present invention, a resin dissolved in a good solvent can be recovered as a granular resin having good handleability while suppressing adhesion between the resins.

  The amount of filler contained in the dispersion is preferably 0.5 to 10% by mass with respect to the poor solvent. The average particle size of the filler is preferably 1 to 100 nm.

  The resin preferably has self-adhesive properties at room temperature. The glass transition temperature of the resin is preferably -80 to 100 ° C. The resin is preferably a polyurethaneimide resin. Since these resins are easy to form large lumps, application of the production method according to the present invention is particularly useful.

  The poor solvent is preferably water.

  The production method according to the present invention preferably further includes a step of washing the recovered granular resin with a washing liquid containing a poor solvent for the resin. The good solvent remaining in the granular resin can be more efficiently removed by washing with a washing solution containing a poor solvent. This cleaning liquid preferably contains a filler.

  According to the production method of the present invention, a resin dissolved in a good solvent can be recovered as a granular resin having good handleability while suppressing adhesion between the resins. Since the granular resins obtained by the production method of the present invention hardly adhere to each other, they can be used while maintaining an appropriate size.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

  In the method for producing a granular resin according to the present embodiment, a resin solution containing a resin and a good solvent in which the resin is dissolved is dropped into a dispersion liquid containing a poor solvent for the resin and a filler to form a granular resin. Is mainly composed of a step of precipitating the liquid in the dispersion and a step of recovering the granular resin from the dispersion.

  The resin is not particularly limited as long as it can be separated from the good solvent by reprecipitation in a poor solvent. A resin having self-adhesive properties at room temperature (for example, 25 ° C.) or a resin having a glass transition temperature of −80 to 100 ° C. is particularly likely to form a large lump during the reprecipitation process, but the method according to this embodiment is applied. By doing so, it can be recovered as a granular resin. The glass transition temperature of the resin is more preferably -60 to 0 ° C. “Having self-adhesion” means that the resins have a property of adhering to each other. Examples of the resin having self-adhesion include polyurethane imide resin. The polyurethaneimide resin is a block copolymer obtained by extending a chain of a urethane oligomer with tetracarboxylic dianhydride.

  A good solvent will not be specifically limited if it is a solvent which melt | dissolves resin. For example, when the resin is a polyurethaneimide resin, the good solvent is preferably N-methyl-2-pyrrolidone.

  The dripping apparatus used for dripping the resin solution is not particularly limited. A resin solution having a low viscosity is dropped by its own weight. The resin solution having a high viscosity is dropped by applying pressure if necessary.

  The filler is not particularly limited as long as it can be dispersed in a poor solvent by stirring. The filler is selected from, for example, silica, talc and organic fine particles. Among these, silica is preferable from the viewpoints of versatility and stability.

  The concentration of the filler in the dispersion is preferably 0.5 to 10% by mass, more preferably 1 to 5% by mass based on the mass of the poor solvent. Increasing the amount of filler can more effectively prevent the particulate resins from adhering in a poor solvent. However, even if the amount of the filler is excessively increased, it is difficult to improve the effect of preventing adhesion between the resins.

  The average particle size of the filler is preferably smaller than the particle size of the granular resin to be obtained. The average particle size of the filler is preferably 1 to 100 nm. The average particle diameter is an average value of the diameters of circumscribed circles when the fillers are observed by TEM, 20 fillers in the TEM image are selected, and the diameters of the circumscribed circles are measured.

  The dispersion is preferably stirred so that the concentration of the filler becomes uniform during the dropping of the resin solution. The stirring method is not particularly limited.

  The poor solvent is not particularly limited as long as the resin does not substantially dissolve. The poor solvent is, for example, at least one solvent selected from water, ethanol, and methanol. Water is a poor solvent for polyurethaneimide resin, and the polyurethaneimide resin can be recovered particularly efficiently by using water.

  When the resin solution is dropped, the temperature of the poor solvent is maintained at a temperature at which the resin is not substantially dissolved in the poor solvent and the poor solvent is not frozen or boiled. For example, in the case of a polyurethaneimide resin, the temperature of the poor solvent is preferably 1 to 30 ° C, more preferably 1 to 20 ° C, and still more preferably 1 to 10 ° C.

  The shape and size of the granular resin are not particularly limited. From the viewpoint of handleability, the diameter of the granular resin is preferably 1 to 10 mm, more preferably 1 to 5 mm, and still more preferably 1 to 3 mm.

  After depositing the granular resin, the resin can be further separated from the good solvent by exchanging the dispersion. The granular resin in the dispersion can be recovered, for example, by filtration. The recovered granular resin is preferably washed with a washing liquid containing a poor solvent for the resin and a filler. By this washing, the good solvent remaining in the resin can be efficiently removed.

  The poor solvent adhering to the collected resin is removed by drying. In order to prevent melting of a resin having a low glass transition temperature and to improve the drying speed, drying is preferably performed under reduced pressure.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1
A resin solution having a viscosity of 0.512 Pa · s obtained by dissolving a polyurethane imide resin having a molecular weight of 73500 in N-methyl-2-pyrrolidone at a concentration of 15% by mass with five 15G nozzles (15G needles manufactured by Musashi Engineering Co., Ltd.) 200 g was dropped into the silica filler dispersion. The silica filler dispersion is added to water, which is a poor solvent for polyurethaneimide resin, with a silica filler having an average particle diameter of 40 nm (Aerosil 50, manufactured by Nippon Aerosil Co., Ltd.) at a concentration of 1% by mass based on the mass of water (500 g) It was prepared by stirring water with a paddle blade. The resin solution was added dropwise to the silica filler dispersion at a rate of 200 g per hour. Along with the dropping, a granular resin was produced in the silica filler dispersion. The produced granular resin contained 20% by mass of N-methyl-2-pyrrolidone.

  In order to further remove N-methyl-2-pyrrolidone from the granular resin, 2500 g of the silica filler dispersion was continuously exchanged over 5 hours. Thereafter, the produced granular resin was recovered from the silica filler dispersion. The recovered granular resin contained about 5% by mass of N-methyl-2-pyrrolidone. Next, in order to improve the drying rate, the granular resin was washed for 1 hour in 500 g of a washing liquid in which 1% by mass of silica filler (manufactured by Nippon Aerosil Co., Ltd., R-972) was dispersed in ethanol, and N-methyl A granular resin containing 0.7% by mass of -2-pyrrolidone was obtained. This resin was dried for 9 hours while heating to 40 ° C. using a vibration type vacuum dryer to obtain a granular resin having a nonvolatile content of 97% by mass.

  The granular resin after drying did not adhere to each other, and each particle existed alone and had good handleability. Silica filler was adhered to the surface of the resin. When the mass of the silica filler remaining as ash was measured, the amount was 1.65% by mass based on the total amount of the resin and the silica filler.

Comparative Example 1
Instead of the silica filler dispersion, the polyurethaneimide resin solution was added dropwise to water containing no silica filler. Otherwise, the same operation as in Example 1 was performed. The produced resins adhered to each other in water, and a granular resin could not be obtained.

Comparative Example 2
A resin solution prepared by dissolving a polyurethaneimide resin having a viscosity of 0.512 Pa · s and a molecular weight of 73500 in N-methyl-2-pyrrolidone at a concentration of 30% by mass was stirred vigorously in the same manner as the method disclosed in Patent Document 1. The precipitate deposited by reprecipitation formed a large lump, and the granular resin could not be recovered.

Claims (9)

Dropping a resin solution containing a resin and a good solvent in which the resin is dissolved into a dispersion containing the poor solvent of the resin and a filler to precipitate the granular resin in the dispersion;
Recovering the granular resin from the dispersion;
The manufacturing method of granular resin provided with.   The method according to claim 1, wherein the amount of the filler contained in the dispersion is 0.5 to 10% by mass with respect to the poor solvent.   The method according to claim 1 or 2, wherein the filler has an average particle size of 1 to 100 nm.   The manufacturing method as described in any one of Claims 1-3 with which the said resin has self-adhesive property at normal temperature.   The manufacturing method as described in any one of Claims 1-4 whose glass transition temperature of the said resin is -80-100 degreeC.   The said resin is a polyurethane imide resin, The manufacturing method as described in any one of Claims 1-5.   The said poor solvent is water, The manufacturing method as described in any one of Claims 1-6.   The manufacturing method as described in any one of Claims 1-7 further equipped with the process of wash | cleaning the collect | recovered granular resin with the washing | cleaning liquid containing the poor solvent of the said resin.   The manufacturing method according to claim 8, wherein the cleaning liquid contains a filler.