JP2005213311A - Method for producing thermosetting resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a thermosetting resin composition, by which the resin composition can be dispersed in a simple apparatus and can be molded into a thick product without limiting the combination of materials and the crystal structures. <P>SOLUTION: This method for producing the thermosetting resin composition comprising inorganic particles having an average particle diameter of 5 to 100 nm and a thermosetting resin is characterized by dispersing a mixture of the inorganic particles with a volatile liquid in a liquid thermosetting resin in a non-cured state and then applying an AC voltage. The frequency of the applied AC voltage is preferably 1 to 10 kHz. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a polymer nanocomposite material for an electric motor that requires heat resistance, light weight and high strength characteristics.

Organic and inorganic nanohybrid materials need to disperse inorganic particles as primary particles in order to develop the nanohybrid effect. Nanoparticles alone aggregate to form secondary particles, and it is difficult to disperse them in a polymer by mechanical treatment such as kneading, and the following method has been adopted.
As a conventional nanoparticle dispersion method, a layered clay compound such as clay is intercalated with a polar organic compound such as amine, separated and dispersed into a nanosize, and the polar organic compound is polymerized to synthesize a polymer. Yes (see, for example, Patent Document 1). In addition, some alkoxides of titanium and silica are synthesized by hydrolyzing by a sol-gel method and incorporated into an epoxy resin skeleton (see, for example, Patent Documents 2 and 3).
The structure of the resin by the former method is shown in FIG. FIG. 6 is a schematic diagram showing the structure of a conventional organic / inorganic nanohybrid material. In FIG. 6, 111 is a layered clay compound such as clay intercalated with a polar organic compound such as amine to make it organic, and separated and dispersed into a nanosize. The polar organic compound is polymerized with the modified polymer 112. Thus, a polymer is synthesized and dispersed in the polymer 113 by a shearing force. As described above, in the conventional nanoparticle dispersion method, the polymer raw material is physically swollen into the fine particle raw material, the nanoparticle is dispersed, and then the polymer is synthesized.
In the latter dispersion method by the sol-gel method, titanium or silica alkoxide is hydrolyzed by the sol-gel method and synthesized by incorporating it into an epoxy resin skeleton. As described above, in the conventional nanoparticle dispersion method, a procedure has been adopted in which a polymer raw material and a fine particle raw material are chemically reacted to precipitate nanoparticles.
Japanese Patent Laid-Open No. 11-092677 JP 2000-319362 A JP 2001-59013 A

However, in the conventional intercalation method, there is a problem that the crystal structure of the inorganic substance and the combination of the inorganic substance and the swelling substance are limited by the combination of the ion exchange property and polarity of both. In addition, in the conventional sol-gel method, an inorganic oxide is produced by hydrolysis. The produced inorganic substance produces a large amount of alcohol as a by-product, and only a thin film is used to remove the alcohol and added water. There is also a problem that it cannot be manufactured.
Therefore, the present invention has been made in view of such problems, and provides a method that can be thickened and can be dispersed with a simple device without any restrictions on the combination of materials and crystal structure. The purpose is to do.

In order to solve the above problem, the present invention is as follows.
Invention of Claim 1 is a manufacturing method of the thermosetting resin composition formed by mixing the inorganic particle with an average particle diameter of 5 nm or more and 100 nm or less, and a thermosetting resin, The said inorganic particle, volatile liquid, After the mixture is dispersed in the liquid thermosetting resin in an uncured state, an alternating voltage is applied.
According to the second aspect of the present invention, the frequency of the AC voltage is 1 kHz or more and 10 kHz or less.
The invention according to claim 3 stirs the liquid thermosetting resin when the voltage is applied.
In a fourth aspect of the present invention, the boiling point of the volatile liquid is set to 200 ° C. or less in the atmosphere in which the voltage is applied.
According to a fifth aspect of the present invention, the atmosphere is reduced to an atmospheric pressure or lower when the voltage is applied.
Invention of Claim 6 is a thermosetting resin composition obtained by the manufacturing method in any one of the said Claim 1 to 5.

According to the first aspect of the present invention, an AC voltage is applied to a thermosetting resin in which a mixture of inorganic particles, volatile liquid, and (gas) is dispersed in an uncured state, and therefore, volatilization occurs due to discharge generated in the gas. Since the ionic liquid evaporates and disperses the primary particles by aggregating the inorganic particles, it is not necessary to remove alcohol, moisture, etc., eliminating restrictions on the combination of materials and crystal structure with a simple device, and Can be thickened.
According to the invention described in claim 2, since the frequency of the alternating voltage is set to 1 kHz or more, the discharge energy in the gas is increased and easily dispersed, and the frequency is set to 10 kHz or less. Since it can suppress, the restrictions of a combination of materials and a crystal structure can be eliminated.
According to the invention described in claim 3, since the liquid thermosetting resin composition is agitated when a voltage is applied, the primary particles that have been flocculated by evaporation of the volatile liquid are quickly dispersed in the thermosetting resin. Since it is possible to suppress the thermal deterioration of the organic matter due to the discharge, it is possible to eliminate restrictions on the combination of materials and the crystal structure.
According to the invention described in claim 4, since the boiling point of the volatile liquid is set to 200 ° C. or lower, the primary particles can be quickly dispersed in the thermosetting resin, and the thermal deterioration of the liquid resin during discharge is suppressed. Therefore, restrictions on the combination of materials and the crystal structure can be eliminated.
According to the invention described in claim 5, since the atmosphere is reduced to atmospheric pressure or lower during voltage application, the boiling point of the liquid resin can be lowered, and the primary particles can be quickly dispersed in the thermosetting resin. Since the thermal deterioration of the liquid resin can be suppressed, restrictions on the combination of materials and the crystal structure can be eliminated.
According to the invention described in claim 6, since the thermosetting resin composition obtained by the manufacturing method according to any one of claims 1 to 5 can disperse the inorganic particles and disperse in the primary particles, A resin composition for an electric motor having a large heat resistance and a light weight and high strength can be obtained.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing the configuration of a nanoparticle dispersion apparatus to which the method of the present invention is applied. In the figure, 1 is a secondary particle, 2 is a primary particle, 3 is a volatile liquid, 4 is a bubble, 5 is a liquid thermosetting resin, 6 is a stirring vessel, 7 is an AC power source, 8 is an electrode, and 9 is stirring. It is a feather.
The secondary particles 1 are produced during the manufacturing process, and the details are shown in FIG. FIG. 2 is an enlarged cross-sectional view of secondary particles in which nanoparticles are aggregated.
The secondary particles 1 in which the nanoparticles are aggregated are composed of primary particles 2, a volatile liquid 3, and bubbles 4, and are dispersed in a liquid thermosetting resin 5. The stirring vessel 6 includes an electrode 8 wired from an AC power source 7 so that an AC voltage can be applied to the mixture of the secondary particles 1 and the liquid thermosetting resin 5. Further, by using the stirring blade 9 also as the electrode 8, shearing by stirring is given to the mixture of the secondary particles 1 and the liquid thermosetting resin 5 while applying an AC voltage.
Next, a method for producing the thermosetting resin composition of the present invention will be described with reference to FIG.
FIG. 3 is a flowchart showing a processing procedure for dispersing nanoparticles into primary particles.
(1) First, in Step 1, the volatile liquid 3 is added in an amount equal to or less than the liquid absorption amount of the nanoparticulate powder and kneaded to prepare a paste containing the gas in the atmosphere as bubbles 4.
(2) In Step 2, when the paste prepared in Step 1 and the liquid resin 5 are put into the stirring vessel 6 and the stirring blade 9 is rotated, the paste is finely dispersed in the liquid resin 5 and becomes the secondary particles 1. .
(3) In step 3, an AC voltage is applied between the electrodes 8. The voltage is increased at a rate of 1 kV / min, and the partial discharge current generated in the bubbles 4 in the secondary particles 1 is observed by an ammeter (not shown) provided in the AC power supply 7. When the increase in the partial discharge current is saturated, the voltage is fixed at a predetermined voltage equal to or higher than the voltage at the time of saturation, and when the partial discharge is stopped, the voltage application is stopped. Stirring is continued during voltage application.
(4) Finally, in step 4, a curing agent is added to and mixed with the resin in which the nanoparticles are dispersed, and cured to a predetermined shape.
As described above, the discharge energy generated by the partial discharge generated in the secondary particles 1 evaporates and expands the volatile liquid, so that the nanoparticles can be aggregated and the primary particles can be dispersed in the liquid resin.
Next, as an example of the present invention, a liquid thermosetting resin will be described using an epoxy resin. The materials used for the epoxy resin composition of the present invention are as follows.
A. Nanoparticles: sprayed silica (average particle size 7 nm), titanium oxide (average particle size 30 nm), polishing alumina (average particle size 100 nm), crystalline silica (average particle size 500 nm)
B. Volatile liquid: methanol, acetone C.I. Liquid resin: bisphenol A type epoxy resin (epoxy equivalent 190)
D. Curing agent: Boron trifluoride monoethylamine complex Table 1 shows production conditions obtained by variously combining the epoxy resin composition of the present invention and voltage application conditions. In addition, as a comparative example, a dispersion in which crystalline silica having a large average particle diameter of 500 nm and a conventional one in which no voltage is applied were also added. The curing conditions for these mixtures were all set to 150 ° C. and 5 hours.
About the hardened | cured material produced on the conditions shown in Table 1, the dynamic viscoelasticity (storage elastic modulus) with respect to each temperature was measured. The result is shown in FIG. The evaluation results in Table 1 are shown in Table 1 with the results of simplifying the degree of decrease in storage modulus based on FIG.
From FIG. 4, in the conventional example in which no voltage was applied, the storage elastic modulus decreased by one digit or more at the glass transition temperature (about 150 ° C.) of the epoxy resin, and a clear glass transition phenomenon appeared. On the other hand, in all the examples to which voltage was applied, the decrease in elastic modulus at the glass transition temperature was reduced, and the effect of restraining the molecular motion of the epoxy resin due to the hybrid effect of the nanoparticles was observed. Among them, the decrease width of sprayed silica having a small particle diameter was the smallest, and the decrease width was smaller as the voltage application conditions were higher voltage and higher frequency. In addition, the general tendency seen in the nano-hybrid effect appears that the smaller the particle size, the greater the effect of constraining the epoxy resin molecular chains, and the higher the voltage and the higher the frequency, the volatile liquid evaporates in a shorter period of time. It was easy to disperse completely.
In the comparative example in which a large silica having an average particle size of 500 nm was dispersed, a clear glass transition phenomenon appeared regardless of the presence or absence of voltage application. This is presumably because the particle size is such that the nano-hybrid effect is difficult to be exhibited and the particle size can be easily primary dispersed only by stirring. Therefore, it can be seen that the upper limit of the particle diameter used in the present invention is approximately 100 nm.
Incidentally, when the treatment was performed at a frequency of 10 kHz or more, the entire stirring vessel was overheated due to heat generation that was probably caused by dielectric heat generation of the liquid resin 5. Therefore, the frequency is preferably 10 kHz or less. The lower limit of the frequency may be 50 Hz, which is a commercial frequency, as long as discharge is generated, and is preferably 1 kHz or more in order to increase the efficiency of voltage application.

In this example, the boiling point of the volatile liquid and the effectiveness of reducing the pressure in the stirring vessel atmosphere during voltage application were examined. The materials used for the epoxy resin composition are as follows.
A. Nanoparticle: Sprayed silica (center particle size 7nm)
B. Volatile liquid: diethyl ether (standard boiling point 34.5 ° C), methanol (standard boiling point 64.7 ° C), cresol (standard boiling point 201 ° C)
C. Liquid resin: bisphenol A type epoxy resin (epoxy equivalent 190)
D. Curing agent: Boron trifluoride monoethylamine complex Table 2 shows the material composition of the epoxy resin composition of the present invention and the presence or absence of reduced pressure. The curing conditions for these mixtures were 150 ° C. and 5 hours. The voltage application conditions were 500 V, 1 kHz, and 20 seconds. The pressure was reduced with an oil rotary rotary pump. The pressure is approximately 0.1 torr.
About the hardened | cured material produced on the conditions shown in Table 2, the dynamic viscoelasticity (storage elastic modulus) with respect to each temperature was measured similarly to Example 1. FIG. The result is shown in FIG. The evaluation results of Table 2 are shown in Table 2 with the results of simplifying the degree of decrease in storage modulus based on FIG.
As can be seen from FIG. 5, in Samples 7 to 9 where voltage was applied under atmospheric pressure, the lower the normal boiling point, the smaller the decrease in the elastic modulus at the glass transition temperature, and the effect of the present invention that was quickly vaporized with the discharge energy. Appeared remarkably. Further, in Sample 9 where the boiling point of the volatile liquid exceeded 200 ° C., coloring that was considered to be carbonization of some constituent materials was observed. On the other hand, the samples 10 to 12 subjected to the decompression of the present invention showed a smaller decrease in elastic modulus than the conditions 7 to 9 in which a voltage was applied under atmospheric pressure, and lowered the boiling point of the present invention. The effect was even more pronounced.

  Thick parts that require heat resistance and strength because the secondary particles can be dispersed in the liquid resin as primary particles because the procedure is to stir and mix while applying voltage to the secondary particles of nanoparticles and the liquid resin. It can also be applied to such applications

Sectional drawing which shows the structure of the nanoparticle dispersion | distribution apparatus to which the method of this invention is applied. Enlarged sectional view showing the structure of secondary particles in the present invention The flowchart which shows the process sequence of the method of this invention. The graph which shows the dynamic viscoelastic property of the thermosetting resin composition of Example 1 The graph which shows the dynamic viscoelastic property of the thermosetting resin composition of Example 2 Schematic diagram showing the structure of an organic / inorganic nanohybrid material produced by a conventional method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Secondary particle 2 Primary particle 3 Volatile liquid 4 Bubble 5 Liquid thermosetting resin 6 Stirrer container 7 AC power source 8 Electrode 9 Stirrer blade 111 Layered clay compound 112 such as clay 112 Modified polymer 113 Polymer

Claims (6)

In the method for producing a thermosetting resin composition obtained by mixing inorganic particles having an average particle diameter of 5 nm or more and 100 nm or less and a thermosetting resin,
A method for producing a thermosetting resin composition, wherein an alternating voltage is applied after a mixture of the inorganic particles and a volatile liquid is dispersed in the liquid thermosetting resin in an uncured state.   The method for producing a thermosetting resin composition according to claim 1, wherein the frequency of the AC voltage is 1 kHz or more and 10 kHz or less.   The method for producing a thermosetting resin composition according to claim 1 or 2, wherein the liquid thermosetting resin is stirred when the voltage is applied.   The method for producing a thermosetting resin composition according to any one of claims 1 to 3, wherein the volatile liquid has a boiling point of 200 ° C or less in the atmosphere in which the voltage is applied.   The method for producing a thermosetting resin composition according to any one of claims 1 to 4, wherein the atmosphere is reduced to an atmospheric pressure or lower when the voltage is applied.   A thermosetting resin composition obtained by the method for producing a thermosetting resin composition according to claim 1.

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