Thermosetting resin composition and method for producing cured resin using same

Abstract

To provide a thermosetting resin composition that achieves both shortening of curing time and sufficient curing.SOLUTION: The thermosetting resin composition according to an embodiment of the present invention contains (A) a thermosetting resin and (B) a microwave sensitive agent, in which (A) the thermosetting resin is in an uncured state and (B) the microwave sensitive agent has an average particle size of 100 μm or less and satisfies a particular formula (1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a thermosetting resin composition and a method for producing a cured resin product using the same. [Background technology]

[0002] Thermosetting resins are widely used, but they take a long time to cure and consume a lot of energy. Therefore, heating by microwave irradiation has been proposed to shorten the curing time.

[0003] For example, Patent Document 1 discloses a thermosetting resin composition for microwave irradiation reaction, which is used to form a line-shaped cured resin product by being irradiated with microwaves after being molded into a line shape, and which has a product of the relative dielectric constant and the dielectric loss tangent after curing of 0.2 or more under conditions of 1 GHz and 25°C. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-291316 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional techniques have room for improvement in terms of achieving both a shortened curing time and sufficient curing.

[0006] An object of one aspect of the present invention is to provide a thermosetting resin composition that achieves both a shortened curing time and sufficient curing. [Means for solving the problem]

[0007] As a result of intensive research to solve the above problems, the present inventors have found that adding a microwave sensitizer that satisfies specific parameters to a thermosetting resin makes it possible to shorten the curing time while achieving sufficient curing, and have thus completed the present invention. The present invention includes the following aspects. <1> A thermosetting resin composition comprising (A) a thermosetting resin and (B) a microwave sensitizer, wherein (A) the thermosetting resin is in an uncured state, and (B) the microwave sensitizer has an average particle size of 100 μm or less, and satisfies the following formula (1): 120≦X×Y≦2200 (1) X: (B) Relative dielectric constant of microwave sensitizer. Y: (B) Content (wt%) of microwave sensitizer in the thermosetting resin composition. <2> (B) the boiling point and / or decomposition temperature of the microwave sensitizer is 150°C or higher; <1> The thermosetting resin composition according to claim 1. <3> (A) the thermosetting resin is at least one selected from the group consisting of an epoxy resin, a phenolic resin, a polyimide, a crosslinkable acrylic resin, a bismaleimide-triazine resin, a crosslinkable silicone resin, a benzoxazine resin, and a vulcanized rubber; <1> or <2> The thermosetting resin composition according to claim 1. <4> (B) the microwave sensitizer is one or more selected from the group consisting of ferrite, barium titanate, potassium sodium tartrate (Rochelle salt), barium oxide, titanium dioxide, ammonium ferrous sulfate, methylammonium aluminum sulfate, SbSI, lead titanate, lead zirconate titanate, copper oxalate, ammonium phosphate, lead nitrate, ethylene glycol, propylene glycol, glycerin, and furfural; <1> ~ <3> 10. The thermosetting resin composition according to claim 9 . <5> <1> ~ <4> 13. A method for producing a cured resin product, comprising: irradiating the thermosetting resin composition according to any one of claims 1 to 12 with microwaves. <6> The microwave irradiation time is 1 to 5 minutes. <5> 2. A method for producing a cured resin product according to claim 1 . Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a thermosetting resin composition that achieves both a shortened curing time and sufficient curing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The embodiments of the present invention will be described in detail below. Unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more (including A and larger than A) and B or less (including B and smaller than B)."

[0010] [1. Thermosetting resin composition] A thermosetting resin composition according to one embodiment of the present invention contains (A) a thermosetting resin and (B) a microwave sensitizer, wherein (A) the thermosetting resin is in an uncured state, and (B) the microwave sensitizer has an average particle size of 100 μm or less and satisfies the following formula (1). 120≦X×Y≦2200 (1) X: (B) Relative dielectric constant of microwave sensitizer. Y: (B) Content (wt%) of microwave sensitizer in the thermosetting resin composition.

[0011] The microwave sensitizer efficiently absorbs microwaves and generates heat, thereby accelerating the thermosetting reaction. In addition, by using a microwave sensitizer so as to satisfy formula (1), it is possible to achieve both a shortened curing time and sufficient curing. The shortened curing time leads to a reduction in the required energy, which is also preferable from the viewpoint of energy saving.

[0012] The thermosetting resin composition includes an uncured thermosetting resin. That is, in this specification, the thermosetting resin composition means a resin composition before curing. The thermosetting resin composition is obtained by mixing each component described below.

[0013] <1-1. Thermosetting resin> Examples of thermosetting resins include epoxy resins, phenolic resins, polyimides, crosslinkable acrylic resins, bismaleimide-triazine resins, crosslinkable silicone resins, benzoxazine resins, vulcanized rubber, etc. These may be used alone or in combination of two or more. From the viewpoint of a large effect of shortening the curing time by microwave irradiation, benzoxazine resins, phenolic resins, polyimides, and bismaleimide-triazine resins are preferred.

[0014] A curing agent or curing accelerator may be used to accelerate the curing of the thermosetting resin. Examples of the curing agent include phenolic resins such as phenol novolac resin, cresol novolac resin, and naphthalene-type phenolic resin; amino resins, urea resins, melamine, and dicyandiamide. Examples of the curing accelerator include phosphine-based compounds such as triphenylphosphine; amine-based compounds such as tertiary amines, trimethanolamine, triethanolamine, and tetraethanolamine; borate-based compounds such as 1,8-diaza-bicyclo[5,4,0]-7-undecenium tetraphenylborate; imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 2-isopropylimidazole, 2,4-dimethylimidazole, and 2-phenyl-4-methylimidazole. imidazoles such as 2-methylimidazoline, 2-ethylimidazoline, 2-isopropylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2,4-dimethylimidazoline, 2-phenyl-4-methylimidazoline, and other imidazolines; azine-based imidazoles such as 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, and 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine. These may be used alone or in combination of two or more.

[0015] <1-2. Microwave Sensitizer> In this specification, the microwave sensible agent means a substance that absorbs microwaves and generates heat. The relative dielectric constant of the microwave sensible agent is preferably 20 to 4400, more preferably 30 to 4000, and further preferably 30 to 3000. In each of the numerical ranges of the relative dielectric constant of these microwave sensible agents, the lower limit may be 40, 100, or 200. The relative dielectric constant is the ratio of the dielectric constant of a medium to the dielectric constant of a vacuum, and is a dimensionless quantity. If the relative dielectric constant of the microwave sensible agent is within the above range, it can efficiently absorb microwaves and efficiently generate heat. The relative dielectric constant can be measured by a resonance method, a capacitance method, a frequency change method, or the like.

[0016] The average particle size of the microwave sensitizer is 100 μm or less, preferably 50 μm or less, and more preferably 20 μm or less. A microwave sensitizer having an average particle size of 100 μm or less can increase dispersibility in a resin, so that a small amount is sufficient, and has a large surface area, so that it has high thermal conductivity. Therefore, the thermosetting resin can be cured efficiently. In this specification, the average particle size means a value measured by a dynamic light scattering method, a laser diffraction method, a centrifugal sedimentation method, or the like. In addition, there are also compounds (e.g., liquid compounds) that can be compatible with a thermosetting resin without taking a particle form, such as ethylene glycol, which will be described later. In the case of such compounds, each of the fine molecules that are compatible with and dispersed in a thermosetting resin is regarded as a "microwave sensitizer having an average particle size of 100 μm or less". In other words, in this specification, a microwave sensitizer having an average particle size of 100 μm or less means to include a compound that is compatible with a thermosetting resin without taking a particle form.

[0017] The content of the microwave sensitizer in the thermosetting resin composition is preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, and further preferably 1 to 5% by weight. If the content of the microwave sensitizer is 0.5% by weight or more, the heat generation by microwaves and the curing associated therewith proceed sufficiently. If the content of the microwave sensitizer is 15% by weight or less, the microwaves reach the inside of the resin composition, and the curing of the inside of the resin composition also proceeds sufficiently. If the amount of the microwave sensitizer is too large, a large amount of microwaves are absorbed on the surface of the resin composition, and there is a risk that the microwaves will not reach the inside of the resin composition. Patent Document 1 does not disclose anything about the content of such microwave sensitizer.

[0018] By setting X×Y to 120 or more, the effect of the microwave sensitizer can be fully exhibited. Furthermore, by setting X×Y to 2200 or less, inhibition of curing inside the resin composition due to excessive microwave absorption on the surface of the resin composition can be suppressed. X×Y is preferably 150 or more, more preferably 180 or more, and even more preferably 250 or more. Furthermore, X×Y is preferably 2000 or less, more preferably 1800 or less, and even more preferably 1500 or less.

[0019] The boiling point and / or decomposition temperature of the microwave sensitizer is preferably 150° C. or higher, and more preferably both the boiling point and the decomposition temperature are 150° C. or higher. This makes it possible to prevent the microwave sensitizer from evaporating and / or decomposing even if heat is generated by microwave irradiation, and as a result, the thermosetting resin composition can be stably cured.

[0020] The microwave sensitizer may be an inorganic or organic compound. The microwave sensitizer may be an oxide, a halide, a sulfate, a nitrate, a phosphate, or an oxalate. The microwave sensitizer may also include a metal. Alternatively, the microwave sensitizer may be an alcohol or an aldehyde.

[0021] For example, microwave sensitizers include ferrite, barium titanate, potassium sodium tartrate (Rochelle salt), barium oxide, titanium dioxide, and ammonium ferrous sulfate (NH 4 Fe(SO 4 ) 2 12H 2 O), aluminum methylammonium sulfate (CH 3 NH 3 Al(SO 4 ) 2 12H 2 O(MASD)), SbSI, lead titanate, lead zirconate titanate (Pb(Zr 0.54 Ti 0.46 )O 3 ), copper oxalate (Cu(HCOO) 2 4H 2 O), ammonium phosphate (NH 4 H 2 PO 4 ), lead nitrate, ethylene glycol, propylene glycol, glycerin (glycerol), furfural, KH 2 PO 4 , LiNbO 3 , PbCl 2 , PbO, titanium oxide, Cd 2 Nb 2 O 7 , (NH 4 )HSO 4 , K.I.O. 3 , Bi 4 Ti 3 O 12 , (CH 3 NHCH 2 COOH) 3 CaCl 2 , SC(NH 2 ) 2 , (Na 0.5 Bi 0.5 )TiO 3 , B.A. 2 NaNb 5 O 15 , Sr 2 Nb 2 O 7 , SrBi 2 Ta 2 O 9 , Pb5 Ge 3 O 11 , PbHfO 3 , PbZrO 3 Examples of ferrite include Mn-Zn ferrite. These may be used alone or in combination of two or more. The relative dielectric constants of these substances are shown in Tables 1 and 2 below.

[0022] [Table 1]

[0023] [Table 2]

[0024] As shown in Tables 1 and 2, there are microwave sensitizers whose known relative dielectric constants have a wide range of values. Even in such cases, a person skilled in the art can appropriately measure the relative dielectric constant of the microwave sensitizer to be actually used by a resonance method, a capacitance method, a frequency change method, or the like. Therefore, a person skilled in the art can confirm that the relative dielectric constant of the microwave sensitizer to be actually used is within the above-mentioned preferable range, and then adjust the content of the microwave sensitizer so as to satisfy formula (1).

[0025] Among these, from the viewpoints of cost and availability, the microwave sensitizer is preferably one or more selected from the group consisting of ferrite, barium titanate, potassium sodium tartrate (Rochelle salt), barium oxide, titanium dioxide, ammonium ferrous sulfate, ammonium aluminum sulfate, SbSI, lead titanate, lead zirconate titanate, copper oxalate, ammonium phosphate, lead nitrate, ethylene glycol, propylene glycol, glycerin, and furfural.

[0026] <1-3. Other ingredients> The thermosetting resin composition may contain various additives such as flame retardants, nucleating agents, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, lubricants, flame retardant assistants, antistatic agents, antifogging agents, fillers, softeners, plasticizers, and colorants. These may be used alone or in combination of two or more. The content of the additives in the thermosetting resin composition is not limited and may be, for example, 0 to 20% by weight, 0 to 10% by weight, 0 to 5% by weight, or 0 to 1% by weight.

[0027] 2. Method for producing cured resin The method for producing a cured resin according to one embodiment of the present invention includes a step of irradiating the above-mentioned thermosetting resin composition with microwaves. This allows a sufficiently cured cured resin to be obtained in a short time. The method may further include a step of mixing the above-mentioned (A) uncured thermosetting resin and (B) microwave sensitizer so as to satisfy the above formula (1) to prepare a thermosetting resin composition.

[0028] The microwave wavelength is preferably 0.3 to 30 GHz, and more preferably 1 to 20 GHz. When the microwave wavelength is in the above range, the thermosetting resin composition can be efficiently heated. The heating temperature is preferably such that the temperature of the uncured resin composition is 150 to 250°C, and more preferably 170 to 200°C.

[0029] The microwave irradiation time is preferably 1 to 10 minutes, more preferably 1 to 5 minutes, and even more preferably 1 to 3 minutes. The above-mentioned thermosetting resin composition efficiently absorbs microwaves, so that it can be cured in such a short time.

[0030] The thickness of the obtained cured resin may be 0.1 to 300 mm, or may be 10 to 100 mm. The thickness of the thermosetting resin composition to which microwaves are irradiated may be set to the above-mentioned thickness. Since the above-mentioned thermosetting resin composition efficiently absorbs microwaves, a cured product having a certain thickness can be efficiently obtained by the above-mentioned production method. Note that the "thickness" referred to here means the maximum thickness of the obtained cured resin or the thermosetting resin composition used as a material.

[0031] 3. Uses of the thermosetting resin composition Applications of the thermosetting resin composition include, for example, films, sheets, containers, housings, building materials, dolls, and structural materials.

[0032] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. EXAMPLES

[0033] Examples and comparative examples are presented below to explain one embodiment of the present invention, but the present invention is not limited thereto.

[0034] [Method of measuring degree of cure] The cured resin obtained in the examples and comparative examples described below was crushed uniformly. 2 to 5 mg of the crushed cured resin was sampled, and the area of ​​the exothermic peak was determined by DSC analysis. In addition, the area of ​​the exothermic peak was determined similarly by DSC analysis using the resin composition before curing in each of the examples and comparative examples. The degree of cure was estimated from the ratio of the area of ​​the exothermic peak of the cured resin to the area of ​​the exothermic peak of the resin composition before curing.

[0035] Example 1 1% by weight of ferrite (relative dielectric constant 240-300) as a microwave sensitizer was added to benzoxazine resin Pd (manufactured by Shikoku Kasei), which is a thermosetting resin, in a mortar and mixed while grinding. The average particle size of the ground ferrite was 12 μm. This resulted in a thermosetting resin composition. The thermosetting resin composition was filled into a mold. Next, the thermosetting resin composition was irradiated with microwaves (2.455 GHz) at 200°C for 1 minute using a microwave synthesis device Monowave 300 manufactured by Anton Paar. This resulted in a resin cured product. The shape of the obtained resin cured product was a cylinder with a diameter of 5 mm and a height of 5 mm.

[0036] [Examples 2 to 4, Comparative Examples 1 to 8] A resin cured product was obtained in the same manner as in Example 1, except that the type and content of the microwave sensitizer, the heating method, and the heating time were changed as shown in Table 3 below. The average particle size of SiC in the thermosetting resin composition was 16 μm, and the average particle size of ferrite was 12 μm. Meanwhile, in the thermosetting resin composition, ethylene glycol and glycerol were compatible with the thermosetting resin (benzoxazine resin Pd). The relative dielectric constant of ethylene glycol is 37 to 38.7, the relative dielectric constant of glycerol is 41 to 47, and the relative dielectric constant of SiC is 9.66 to 10.33.

[0037] [Examples 5 to 9, Comparative Examples 9 to 12] A cured resin was obtained in the same manner as in Example 1, except that the thermosetting resin was changed to JBZ-BA100(Ba) manufactured by JFE Chemical, and the type and content of the microwave sensitizer, the heating method, and the heating time were changed as shown in Table 4 below. The average particle size of the ferrite in the thermosetting resin composition was 12 μm. Meanwhile, in the thermosetting resin composition, ethylene glycol and glycerol were compatible with the thermosetting resin (JBZ-BA100(Ba)).

[0038] [Evaluation results] The evaluation results of Examples 1 to 4 and Comparative Examples 1 to 8 are shown in Table 3 below.

[0039] [Table 3]

[0040] Examples 1 to 4, which contain a microwave sensitizer that satisfies the specific particle size, relative dielectric constant, and content, and satisfies formula (1), achieved a good degree of curing by irradiating microwaves for 1 or 3 minutes. In contrast, Comparative Example 1, which did not use a microwave sensitizer and was irradiated with microwaves for 1 minute, showed a poor degree of curing. Comparative Examples 2 and 3, which contain a microwave sensitizer but do not satisfy formula (1), also showed a poor degree of curing. As can be seen from Comparative Examples 4 to 7, when an oven was used, it took a long time for curing. Comparative Example 8, which uses SiC with a low relative dielectric constant and does not satisfy formula (1), also showed a poor degree of curing.

[0041] The evaluation results of Examples 5 to 9 and Comparative Examples 9 to 12 are shown in Table 4 below.

[0042] [Table 4]

[0043] Examples 5 to 9, which used different types of thermosetting resins from those used in Examples 1 to 4, also showed good degrees of cure. In addition, good degrees of cure were obtained even when the heating temperature was lowered as in Examples 6 and 7. Comparative Example 9, which did not use a microwave sensitizer, showed poor degrees of cure. As can be seen from Comparative Examples 10 to 12, when an oven was used, it took a long time for curing.

[0044] The relationship between X: the relative dielectric constant of the microwave sensitizer, and Y: the content (wt%) of the microwave sensitizer in the thermosetting resin composition in the examples and comparative examples is shown in the following Tables 5 and 6. It can be seen that Examples 1 to 9 satisfy formula (1), but Comparative Examples 1 to 12 do not satisfy formula (1).

[0045] [Table 5]

[0046] [Table 6] [Industrial Applicability]

[0047] The present invention can be used in fields where thermosetting resins are used.

Claims

1. A thermosetting resin composition comprising (A) a thermosetting resin and (B) a microwave sensitizer, (A) the thermosetting resin is in an uncured state; (A) the thermosetting resin comprises a benzoxazine resin; (B) The microwave sensitizer has an average particle size of 100 μm or less and satisfies the following formula (1): (B) the relative dielectric constant of the microwave sensitizer is 20 to 4400; The content of the microwave sensitizer (B) in the thermosetting resin composition is 0.5 to 15% by weight. 120≦X×Y≦2200 (1) X: (B) The relative dielectric constant of the microwave sensitizer. Y: The content (wt %) of the microwave sensitizer (B) in the thermosetting resin composition.

2. The thermosetting resin composition according to claim 1, wherein the boiling point and / or decomposition temperature of the microwave sensitizer (B) is 150°C or higher.

3. 3. The thermosetting resin composition according to claim 1, wherein the thermosetting resin (A) further comprises at least one selected from the group consisting of an epoxy resin, a phenolic resin, a polyimide, a crosslinkable acrylic resin, a bismaleimide-triazine resin, a crosslinkable silicone resin, and a vulcanized rubber.

4. The thermosetting resin composition according to any one of claims 1 to 3, wherein the microwave sensitizer (B) is at least one selected from the group consisting of ferrite, barium titanate, potassium sodium tartrate (Rochelle salt), barium oxide, titanium dioxide, ammonium ferrous sulfate, methylammonium aluminum sulfate, SbSI, lead titanate, lead zirconate titanate, copper oxalate, ammonium phosphate, lead nitrate, ethylene glycol, propylene glycol, glycerin, and furfural.

5. A method for producing a cured resin product, comprising a step of irradiating the thermosetting resin composition according to any one of claims 1 to 4 with microwaves.

6. The method for producing a cured resin product according to claim 5, wherein the microwave irradiation time is from 1 to 5 minutes.

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