JP3192460B2 - Epoxy resin foamable composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel epoxy resin-based foamable composition, and more particularly, to a thermosetting dense foam which is suitably used in the fields of automobiles, vehicles, home appliances, building materials and the like. The present invention relates to a liquid or paste-like foamable composition based on an epoxy resin, which can easily give a foam.

[0002]

2. Description of the Related Art In recent years, in automobiles and the like, weight reduction of a vehicle body for improving fuel efficiency has become an important technical problem in design. Its use has been advanced. In recent years, particularly, in order to simultaneously reduce the weight and increase the rigidity, a lightweight honeycomb composite panel having a sandwich structure in which two steel plates are bonded to a paper honeycomb core has begun to be used for a roof or the like. However, the miniaturization of engines to obtain the same horsepower / liter, the thinning of vehicle body panels, the reduction of air resistance, and the like are currently reaching their limits. The most realistic means for reducing the weight is to reduce the thickness of the vehicle body panel.However, thinning the vehicle body reduces the rigidity and strength of the vehicle body and reduces the soundproofing and vibration proof performance. Invite the situation. On the other hand, as a lightweight and rigid structure, an elastic core material sandwich structure in which a thin material is adhered to a surface material using a plastic material having a high expansion ratio and a dense porous structure with a small average cell diameter as a core material Are well known, and therefore, the plastic foam material having adhesiveness is increasingly used as a surface rigidity reinforcing material for a thin steel plate outer plate of an automobile or the like. By the way, as a method of obtaining a rigid foam using a liquid processing material, for example, (1) a method of adding a pyrolysis gas generating type foaming agent to obtain a foam, and (2) a mechanical method in the presence of a foam stabilizer To obtain a foam by foaming by mechanical stirring (US Patent No. 4
546118, US Pat. No. 992525), (3) A method of obtaining a foam by mixing hollow fine particles (JP-A-60-19033, US Pat. No. 4410)
Nos. 639 and 4605688) are known. As the method (1), for example, a method of heating a composition containing a vinyl chloride resin, an epoxy resin and a foaming agent (JP-A-63-272515), a heat-shrinkable polymer sheet containing a foaming agent And laminating it on a fiber base material and subjecting it to heat processing (Japanese Patent Application Laid-Open No. 56-1592).
No. 69) has been proposed. However, in the former method, for example, there is a possibility that thermal decomposition of the resin occurs at a high temperature such as an electrodeposition coating process in an automobile production line, and it is difficult to increase the thickness of the foamed layer in the latter method, There is a disadvantage that it is difficult to provide high rigidity. In the method (2), a foam is obtained by using a silicone or other foam stabilizer to entrain air, freon gas, or the like into the liquid composition by mechanical shearing with a mixer or a filler. However, for materials like this one,
Since the foam undergoes a drainage phenomenon and collapses during the curing process, there is a disadvantage that it is generally difficult to obtain a foam having a high expansion ratio and a dense cell diameter. Furthermore, the above method (3) has a major drawback in that the viscosity of the whole composition generally increases, which makes application processing and the like difficult. In addition to the above foaming performance, when exposed to a high temperature for a long time at a vertical surface or the like in an electrodeposition coating process in an automobile production line, there are many inconvenient phenomena that the foamed structure slips down. In order to prevent such a phenomenon, there have been developed means for improving the tackiness at ordinary temperature or high temperature and preventing it. As such means, it has been proposed to add an appropriate amount of an NBR-modified epoxy resin, a liquid NBR, a urethane-modified epoxy resin, a castor oil-modified epoxy resin, or the like. In the body, because the foam cell membrane is thin,
At present, there is almost no effect.

[0003]

SUMMARY OF THE INVENTION Under such circumstances, the present invention is to provide a light-weight, high-rigidity, dense foam and to firmly adhere to an oil-surface metal. An object of the present invention is to provide a liquid processing material which can be applied, has high adhesive strength at high temperature, has good heat resistance, and can be applied before an electrodeposition coating step in, for example, the automobile field.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop a liquid processing material having the above-mentioned preferable properties, and as a result, based on a liquid epoxy resin, a methacrylic resin, polybutene, A latent curing agent for epoxy resin, a foaming agent having a decomposition gas generation temperature in a specific range, an epoxy resin-based foamable composition containing a surfactant in a predetermined ratio, and found that the object can be achieved, Based on this finding, the present invention has been completed.

That is, according to the present invention, (B) 10 to 200 parts by weight of a methacrylic resin having an average particle diameter of 300 μm or less per 100 parts by weight of a liquid epoxy resin containing one or more epoxy groups in one molecule. (C) 5 to 50 parts by weight of polybutene having a number average molecular weight of 500 to 10000,
(D) 0.5 to 20 parts by weight of a latent curing agent for epoxy resin, (E) 0.5 to 20 parts by weight of a foaming agent having a decomposition gas generation temperature of 100 to 220 ° C, and (F) 0.05 of a surfactant. ~
An epoxy resin foamable composition characterized by comprising 5 parts by weight. Hereinafter, the present invention will be described in detail.

In the composition of the present invention, the liquid epoxy resin used as the component (A) has one or more epoxy groups in the molecule, and examples thereof include (1) bisphenol A , Bisphenol F
Or diglycidyl ether based on resorcinol, (2) polyglycidyl ether of phenol novolak resin or cresol novolak resin, (3) diglycidyl ether of hydrogenated bisphenol A, (4) glycidylamine type, (5) linear fat Group epoxide type,
(6) Diglycidyl esters of phthalic acid, hexahydrophthalic acid or tetrahydrophthalic acid, and the like.
The epoxy equivalent of these liquid epoxy resins is 100 to
300 are preferable, and 150-250 are particularly preferable.

[0007] These liquid epoxy resins may be used alone or in combination of two or more.
Bisphenol A added with ethylene oxide or propylene oxide to impart toughness and tackiness to the resulting foam
It may be used in combination with a modified epoxy resin such as a type epoxy resin, a dimer acid type epoxy resin, and an epoxy-modified NBR. In the composition of the present invention, a methacrylic resin having an average particle diameter of 300 μm or less is used as the component (B). As the methacrylic resin, polymethyl methacrylate or a copolymer resin of methyl methacrylate having a superior amount of methyl methacrylate and a copolymerizable monomer such as ethyl acrylate or acrylonitrile is used. The preferred average degree of polymerization of the methacrylic resin is such that the average degree of polymerization in terms of polymethyl methacrylate is in the range of 2,000 to 30,000. If the average degree of polymerization is less than 2,000, the melt viscosity at the time of processing becomes low, and it becomes difficult to form a dense cell structure due to flow breakage of the foam cells. Further, if the average degree of polymerization exceeds 30,000, the meltability at the time of processing deteriorates and a high expansion ratio cannot be obtained,
It is not preferable because the effect of the present invention is reduced. Further, the present methacrylic resin has an average particle diameter of 300 μm or less, and preferably 1 to 100 μm. Average particle size is 3
If it exceeds 00 μm, uniform dispersibility with other compositions will be poor.

The amount of the methacrylic resin added is
It is in the range of 10 to 200 parts by weight, preferably 20 to 100 parts by weight, per 100 parts by weight of the liquid epoxy resin as the component (A). If the amount is less than 10 parts by weight, the viscosity during processing becomes too low depending on the viscosity of the epoxy resin as the component (A) and the properties and the amount of the polybutene as the component (C) to be described later. For example, if the content exceeds 200 parts by weight, the meltability during processing deteriorates and a high expansion ratio cannot be obtained. In the composition of the present invention, polybutene is used as the component (C). The polybutene refers to a homopolymer of isobutylene and n-butene or a copolymer of the two, and is generally a material having a predominant amount of isobutylene. Its number average molecular weight is 500-10000,
Preferably it is in the range of 1000-3000. When the number average molecular weight is less than 500, the adhesive strength at high temperature is insufficient and
If it exceeds 0000, the material at normal temperature becomes jelly-like, and the processability of mixing and stirring is poor. Although the amount of addition depends on the number average molecular weight, the liquid epoxy resin 10 (A)
It is 5 to 50 parts by weight, preferably 1 to 0 parts by weight.
0 to 40 parts by weight. If the amount is less than 5 parts by weight, the adhesive strength at a high temperature is insufficient. If the amount exceeds 50 parts by weight, bleeding may occur depending on the number average molecular weight.

In the composition of the present invention, 0.5 to 20 parts by weight of a latent curing agent for epoxy resin is used as the component (D). The curing agent preferably has an exothermic peak temperature in the range of 100 to 200 ° C. in combination with an epoxy resin. Examples of such a curing agent include dicyandiamide, 4,4′-diaminodiphenylsulfone, and
imidazole derivatives such as n-heptadecyl imidazole, isophthalic dihydrazide, N, N'-dialkyl urea derivatives, N, N'-dialkyl thiourea derivatives, acid anhydrides such as tetrahydrophthalic anhydride, isophorone diamine, m- Examples include phenylenediamine, N-aminoethylpiperazine, a boron trifluoride complex compound, and trisdimethylaminomethylphenol.

These curing agents may be used alone or in combination of two or more kinds. The amount of the curing agent is 0.5 per 100 parts by weight of the liquid epoxy resin (A). It is necessary to select in the range of ２０20 parts by weight. If the addition amount is less than 0.5 part by weight, the curing is insufficient and the elastic modulus of the foam is low, and if it exceeds 20 parts by weight, the elastic modulus of the foam does not improve depending on the amount, and it is more economical. Be disadvantaged. In the present invention, together with the curing agent of the component (D), if necessary, for example, an alcohol-based compound,
Phenol-based, mercaptan-based, dimethylurea-based, alicyclic-based, and curing accelerators such as imidazole, monuron, and chlorotoluene can be used.

In the composition of the present invention, a foaming agent having a decomposition gas generation temperature of 100 to 220 ° C. is used as the component (E). As such a high-temperature decomposition type foaming agent, an organic foaming agent, an inorganic foaming agent, a high-temperature expansion type microcapsule and the like can be used. If the decomposition gas generation temperature is lower than 100 ° C., foaming starts before forming into a sheet, the resin does not melt sufficiently during heating and foaming, gas is released and the expansion ratio does not increase, or it is difficult to obtain a uniform foam. . On the other hand, when the temperature exceeds 220 ° C., the processing temperature of the composition becomes too high, and deterioration occurs, so that it is difficult to obtain a foam having good quality. Examples of the organic foaming agent include azodicarbonamide, p-toluenesulfonylhydrazide, dinitrosopentamethylenetetramine, 4,4′-oxybisbenzenesulfonylhydrazide and the like. The decomposition temperature of these organic foaming agents can be arbitrarily adjusted by adding an appropriate amount of urea, zinc compound, lead compound and the like. Examples of the inorganic foaming agent include sodium hydrogencarbonate and sodium borohydride, and examples of the high-temperature expandable microcapsules include, for example, those obtained by encapsulating a low-boiling hydrocarbon with a vinylidene chloride resin.

As the component (E) of the present invention, any of the above-mentioned organic foaming agents, inorganic foaming agents, and high-temperature-expandable microcapsules can be used. It is suitable. These foaming agents may be used alone or in a combination of two or more. The amount of the foaming agent is determined by the amount of the liquid epoxy resin 10 as the component (A).
It is selected in the range of 0.5 to 20 parts by weight with respect to 0 parts by weight. If the addition amount is less than 0.5 part by weight, the expansion ratio is insufficient, and if it exceeds 20 parts by weight, the expansion ratio is not improved in proportion to the addition amount, which is economically disadvantageous. In order to obtain a dense foam having a uniform foam cell diameter and a rigid cell membrane, it is advantageous that the particle diameter of the foaming agent is small, for example, a cell diameter of 0.5 mm or less is obtained. It is desirable that the foaming agent has an average particle diameter of 20 μm or less, preferably 10 μm or less, and a uniform particle diameter distribution. In the composition of the present invention, a foaming accelerator can be used in combination with the foaming agent, if necessary. As this foaming accelerator,
Examples include zinc oxide, lead stearate, calcium stearate, zinc stearate, barium stearate, sodium and potassium compounds, urea and the like.

In the composition of the present invention, a surfactant is used as the component (F). This surfactant plays a role in improving the foam cell structure.
Examples of the surfactant include alkyl sulfates such as sodium lauryl sulfate and sodium myristyl sulfate; alkyl allyl sulfonates such as sodium dodecylbenzenesulfonate and potassium dodecylbenzenesulfonate; sodium dioctyl sulfosuccinate; and dihexyl sulfosuccinate. Anionic surfactants such as sulfosuccinate salts such as sodium silicate, ammonium laurate, fatty acid salts such as potassium stearate, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl allyl sulfate salts, and rosinate salts are preferred. Can be mentioned,
Sorbitan esters such as sorbitan monooleate and polyoxyethylene sorbitan monostearate;
Nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, and polyoxyethylene alkyl esters, and cationic surfactants such as cetyl pyridinium chloride and cetyl trimethyl ammonium bromide can also be used. it can.

These surfactants may be used alone or in combination of two or more. The amount of the surfactant is 0.05 to 5 parts by weight per 100 parts by weight of the liquid epoxy resin (A). 5 parts by weight, preferably 0.2 to 3 parts by weight. If the amount is less than 0.05 part by weight, the effect of homogenizing the foamed cells is poor. If the amount exceeds 5 parts by weight, not only the foamed cells are not homogenized but also the amount of It is not preferable because thermal stability is reduced. Furthermore, in the composition of the present invention, in order to adjust the melt viscosity and the affinity between the liquid epoxy resin of the component (A), the methacrylic resin of the component (B), and the polyethylene resin of the component (C). It is also possible to add a plasticizer if necessary. Examples of the plasticizer include phthalic acid esters such as di-2-ethylhexyl phthalate and dibutyl phthalate, phosphoric acid esters such as tricresyl phosphate, fatty acid esters such as dioctyl adipate, and adipic acid condensation of ethylene glycol. A known substance such as a compound, trimellitic acid triester, glycolic acid ester, chlorinated paraffin, or alkylbenzene can be used.

In the composition of the present invention, an epoxy resin diluent may be added, if necessary, for the purpose of facilitating initial mixing or increasing the amount of fillers and the like. Examples of the diluent include reactive diluents such as butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, glycidyl ether versatate, dibutyl phthalate, tricresyl phosphate, and butyl benzyl diphthalate. , Acetyl tributyl citrate, aromatic process oil, pine oil,
Non-reactive diluents such as 2,2,4-trimethyl-1,3-pentadiol isobutyrate may be mentioned. These diluents are usually used as the liquid epoxy resin 1 (A).
It is usually selected in the range of 5 to 150 parts by weight, preferably 10 to 100 parts by weight, per 100 parts by weight. A thixotropic agent, a filler, a pigment, and the like may be added to the composition of the present invention as necessary for adjusting coating properties such as processability and viscosity, and reducing costs. Examples of the thixotropic agent include silicic acids such as silicic anhydride and hydrous silicic acid, bentonites such as organic bentonite, asbestos such as silodex, and organics such as dibenzylidene sorbitol. These thixotropic agents are usually selected in the range of 1 to 20 parts by weight per 100 parts by weight of the liquid epoxy resin of the component (A).

Examples of the filler include calcium carbonate, mica, talc, kaolin clay, celite, asbestos, perlite, baryta, silica, silica sand, flaky graphite, dolomite limestone, gypsum, and aluminum powder. The epoxy resin-based foamable composition of the present invention uses the above-mentioned essential components (A) to (F) and various additional components used as required in predetermined amounts, for example, a planetary mixer, a kneader, a roll, It can be adjusted with a Henschel mixer or the like. The composition of the present invention is usually heated at a temperature in the range of 140 to 220 ° C. to simultaneously perform the decomposition of the foaming agent and the curing reaction of the epoxy resin, and heat molding such as known sol processing, calendering, and extrusion. By doing so, it is possible to obtain an epoxy resin foam having a high expansion ratio and a dense foam cell having dense toughness and heat resistance.
After forming a semi-cured body at a relatively low temperature below the decomposition temperature of the foaming agent of about 0 ° C. and pasting it to a necessary part, and then heating at a temperature in the range of 140 to 220 ° C. to decompose the foaming agent And a curing reaction of the epoxy resin.

When the foamable epoxy resin composition of the present invention is applied to a stiffness imparting material, a heat insulating material or the like for an outer plate of an automobile or the like, the above-mentioned semi-cured sheet is first prepared, and then cut into a desired shape. Then, this is applied to a heatable portion to which a function such as rigidity is to be imparted at a production site, and then heated and foamed, and at the same time, the epoxy resin in the composition is cured by reaction, and more firmly attached to the portion to be attached. The method of expressing rigidity by bonding is most effective. Further, when the composition of the present invention is applied to an outer panel of an automobile, the composition can be applied even in a process prior to electrodeposition coating in a production line, and the range of use in the same field can be expanded.

Since the composition of the present invention can maintain the decomposition gas of the foaming agent in a dense foam state, the processing range of the curing of the epoxy resin which subsequently reacts is wide, and the apparent appearance of the entire composition when foamed is obtained. The viscosity is maintained in a high state even under heating, so that the curing reaction can proceed without flowing down even when applied to a vertical surface or ceiling surface, and the composition contains a thermoplastic resin Therefore, the viscosity and adhesion to the metal on the oil surface are remarkably improved. The composition of the present invention can also be applied directly to a desired object, or can be processed by directly filling the voids of an object having voids.

[0019]

Next, the present invention will be described in more detail by way of examples, which should not be construed as limiting the present invention. In addition, each physical property was obtained as follows. (1) Displacement resistance at the time of vertical foaming The composition was molded at a temperature not higher than the decomposition temperature of the foaming agent to prepare an unfoamed semi-cured sheet, which was 70 mm long and horizontal. 110mm, placed on a 0.8mm thick steel plate, if necessary, after creating a structure on which the surface material shown separately is further placed,
When this was fixed vertically and heated and foamed at 150 ° C. for 30 minutes, the degree of deviation generated between the steel sheet and the foam was determined according to the following criteria. Note that the deviation is x. ◎: x ≦ 1 mm ： １: 1 mm <x ≦ 2 mm, with some deviation but no practical problem. Δ: 2 mm <x ≦ 5 mm, and there is a practical problem in some parts. X: 5 mm <x, not practical. XX: Peeling

(2) Foaming Ratio, Foam Cell Shape and Denseness The foaming ratio was determined by dividing the thickness of the entire foam layer by the thickness of the semi-cured sheet, and the foam cell shape and denseness were determined according to the following criteria. A: The cells are uniform and dense, and most are closed cells. :: The cells are relatively uniform and dense, with some open cells. Δ: The cells are relatively uneven and coarse, and there are many open cells. ×: cells are uneven and coarse, mostly open cells,
Or almost no foaming.

(3) Stiffness ratio of the structure The composition is molded at a temperature not higher than the decomposition temperature of the foaming agent to form an unfoamed semi-cured sheet, which is placed on a 0.8 mm thick steel sheet, and if necessary. Further, after forming a structure on which a surface material shown separately was mounted thereon, heating foaming and bonding between the layers were performed at 150 ° C. for 30 minutes. By vibrating the structure obtained in this way, the mechanical impedance is obtained, and the resonance frequency is calculated by the following formula based on the shift amount of the 0.8 mm steel plate from the resonance frequency, and the interpolation is performed. The rigidity ratio at 200 Hz was determined by the method. Note that the measurement frequency is 1 to 1000 Hz and the measurement temperature is 2
0, 40, 60 ° C. Stiffness ratio = (fo / f) ² · {(m ₁ + m ₂ ) / m ₁ } where, fo: resonance frequency of the layered structure (Hz) f: resonance frequency of the steel sheet alone (Hz) m ₂ : test Body surface density (g / m ² ) m ₁ : Surface density (g / m ² ) of a single steel sheet. Also, the dimensions of the test piece are 30 × 300 mm.

Examples 1 to 7 and Comparative Examples 1 to 7 Each component of the kind and amount shown in Table 1 was mixed at room temperature using a planetary mixer to prepare a foamable composition, which was then applied to an applicator. It was applied on a release paper to a thickness of 2 mm, and heated in a hot air circulating furnace at 110 ° C. for 90 seconds to prepare an unfoamed semi-cure sheet. Next, after sticking this unfoamed semi-cured sheet to the above-mentioned steel plate, the release paper was peeled off and foaming was performed under the above-mentioned conditions.
In the test for evaluating the rigidity, an unfoamed semi-cured sheet was attached to the above-mentioned steel sheet, and after releasing the release paper, an aluminum plate having a thickness of 150 μm, a glass cloth of 250 g / m ² or a steel foil having a thickness of 80 μm were placed. Then, under the above conditions, heat foaming and bonding between the layers were performed. The epoxy equivalent of the bisphenol A-based epoxy resin used was 185. The decomposition gas generation temperature of the blowing agent azodicarbonamide used was 150 ° C., and the average particle size was 9 μm. Table 2 shows the results of each evaluation.

[0023]

[Table 1]

[0024]

[Table 2]

The subscripts in Table 1 indicate those described below. Note) 1) Polymethyl methacrylate [average degree of polymerization: 3000, passed through a 250 mesh sieve (average particle diameter: 1 μm)] 2) Polymethyl methacrylate / ethyl acrylate copolymer [composition weight ratio: 90 / 10, average degree of polymerization: 6000, 2
What passed through a 50 mesh sieve (average particle size: 1
μm)] 3) Polybutene [HV-35 manufactured by Nippon Petrochemical Co., Ltd., number average molecular weight: 75]
0] 4) Polybutene [HV-300 manufactured by Nippon Petrochemical Co., Ltd., number average molecular weight: 1]
350] 5) Polybutene [HV-1900 manufactured by Nippon Petrochemical Co., Ltd., number average molecular weight:
2700] 6) Liquid NBR [Nipol 1312, manufactured by Nippon Zeon Co., Ltd.] 7) NBR modified epoxy resin [R-1309, manufactured by AC R, Inc., epoxy equivalent: 300] 8) Urethane modified epoxy resin [A. R-1541, epoxy equivalent: 270, manufactured by CRL Co., Ltd. 9) Castor oil-modified epoxy resin [R-1353, manufactured by AC R, Inc., epoxy equivalent: 530] 10) Polybutene [Nippon Petrochemical ( LV-5, number average molecular weight 280) 11) Aerosil [silica anhydride, Degussa, Germany, average particle size: 0.1
3 μm]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

[Table 6]

[0030]

EFFECTS OF THE INVENTION The epoxy resin foamable composition of the present invention can provide a foam having a high expansion ratio, a uniform foam cell diameter, a dense foam, and rigidity and heat resistance. For example, as a material such as a reinforcing material, a heat insulating material, a cushioning material, a packaging material, a sealing material, and a sealing material, it is suitably used in the fields of automobiles, home appliances, building materials, and the like. In particular, in the automotive field, when used as a rigid reinforcing material for vehicle body outer panels, it slips off even if applied in the process before the electrodeposition coating process on the production line or exposed to the high temperature atmosphere of the electrodeposition coating process. Therefore, a suitable reinforcing effect can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI B32B 5/24 101 B32B 5/24 101 15/08 15/08 B62D 29/04 B62D 29/04 A B29K 33:04 63:00 105: 04 B29L 31:30 (72) Inventor Noboru 1-2-1, Yakko, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Nippon Zeon Co., Ltd. R & D Center (72) Inventor Asako Shinaga Yakko, Kawasaki-ku, Kawasaki-shi, Kanagawa 1-2-1 Nippon Zeon Co., Ltd. R & D Center (72) Inventor Seiki Yada 1-2-1 Yoko, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Nippon Zeon Co., Ltd. R & D Center (72) Inventor Toshio Nagase 1-2-1, Yoko, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Zeon Corporation R & D Center (56) References JP-A-4-264142 ( JP, A) JP-A-56-90842 (JP, A) JP-A-5-194780 (JP, A) JP-A-63-272515 (JP, A) JP-B-47-51827 (JP, B1) JP-B 1975-31394 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 9/00-9/42 C08L 1/00-101/16

Claims (1)

(57) [Claims] 1. A methacrylic resin having an average particle size of 300 μm or less per 100 parts by weight of a liquid epoxy resin (A) containing one or more epoxy groups in one molecule.
00 parts by weight, (C) 5 to 50 parts by weight of polybutene having a number average molecular weight of 500 to 10000, (D) 0.5 to 20 parts by weight of a latent curing agent for an epoxy resin, and (E) a decomposition gas generation temperature of 100 to 220. An epoxy resin foamable composition comprising 0.5 to 20 parts by weight of a foaming agent at a temperature of 0.05 ° C. and 0.05 to 5 parts by weight of a surfactant (F).