JP2548656B2 - Epoxy resin type 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 specifically, it is a thermosetting dense composition suitable for use in the fields of automobiles, vehicles, home appliances, building materials and the like. The present invention relates to an epoxy resin-based liquid or paste foamable composition capable of easily giving a foam.

[0002]

2. Description of the Related Art In recent years, in automobiles and the like, reducing the weight of the vehicle body to improve the fuel consumption thereof has become an important technical problem in designing. For example, the use of plastic outer panels, lightweight materials such as aluminum members and high-tensile steel plates. It has been used. In addition, particularly recently, in order to bring about weight reduction and high rigidity at the same time, a honeycomb lightweight 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, under the present circumstances, miniaturization of an engine for obtaining the same horsepower / liter, thinning of a vehicle body panel, low air resistance, etc. are approaching their limits. The most practical means for reducing the weight is to reduce the thickness of the vehicle body panel, but it is not preferable because the reduction in thickness reduces the vehicle body rigidity, strength, etc., and also reduces the soundproofing and antivibration performance. Bring a situation. On the other hand, as a lightweight and rigid structure, an elastic core material sandwich structure in which a plastic material having a high expansion ratio and a dense porous structure with a small average cell diameter is used as a core material and a thin material is bonded to a surface material Are well known, and therefore, the plastic foam material having adhesiveness has come to be frequently used as a surface rigidity reinforcing material for a thin steel outer panel of an automobile or the like. By the way, as a method for obtaining a hard foam using a liquid processing material, for example, (1)
A method of obtaining a foam by adding a pyrolysis gas generating type foaming agent, (2) a method of foaming by foaming by mechanical stirring in the presence of a foam stabilizer (US Pat. No. 4,546,118) Soviet Patent No. 992525), and (3) a method of mixing hollow fine particles to obtain a foam (JP-A-60-19).
033, U.S. Pat. No. 4,410,639, 460
5688 specification) and the like are known. Examples of the method (1) include a method in which a composition containing a vinyl chloride resin, an epoxy resin, and a foaming agent is heat-processed (JP-A-63-272515), a heat-shrinkable polymer sheet containing a foaming agent. There has been proposed a method of laminating the resin on a fiber base material and heating it (JP-A-56-159269). However, in the former method, for example,
There is a risk of thermal decomposition of the resin at high temperatures such as the electrodeposition coating process in automobile production lines, and it is difficult to increase the thickness of the foam layer by the latter method, so it is difficult to impart high rigidity There are drawbacks. In addition, (2)
In the method of (1), a foam stabilizer such as a silicone-based foam stabilizer is used, and air or freon gas is entangled in the liquid composition by mechanical shearing with a mixer or a flipper to obtain foam. In such a material, since foam causes a drainage phenomenon and collapses during the curing process, it is generally difficult to obtain a foam having a high expansion ratio and a dense cell diameter. Further, the above method (3) has a major drawback that the coating process is difficult because the viscosity of the entire composition generally increases.

[0003]

Under the circumstances described above, the present invention provides a dense foam which is lightweight and has high rigidity, and is capable of firmly adhering to an oil surface metal. The object of the present invention is to provide a liquid processing material which can be applied and has good heat resistance and which can be applied before the electrodeposition coating step, for example, in the field of automobiles.

[0004]

The inventors of the present invention have conducted extensive 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 and a polyethylene resin have been used. That the purpose can be achieved by an epoxy resin-based foamable composition containing a resin, a latent curing agent for an epoxy resin, a foaming agent having a decomposition gas generation temperature in a specific range, and a surfactant in a predetermined ratio. They have found the present invention and have completed the present invention based on this finding. That is, the present invention relates to (A) 10 to 200 parts by weight of a methacrylic resin having an average particle diameter of 300 μm or less, and (C) per 100 parts by weight of a liquid epoxy resin containing one or more epoxy groups in one molecule. ) 10 to 200 parts by weight of a polyethylene resin having a melt index of 100 or less and an average particle diameter of 300 μm or less, (D) a latent curing agent for an epoxy resin of 0.5 to 20 parts by weight, and (E) a decomposition gas generation temperature The present invention provides an epoxy resin-based foamable composition characterized by comprising 0.5 to 20 parts by weight of a foaming agent at 100 to 220 ° C. and 0.05 to 5 parts by weight of a (F) surfactant. Hereinafter, the present invention will be described in detail.

The liquid epoxy resin used as the component (A) in the composition of the present invention has one or more epoxy groups in the molecule. Examples of such a liquid epoxy resin include (1) bisphenol A. , Bisphenol F
Or a diglycidyl ether based on resorcin,
(2) Polyglycidyl ether of phenol novolac resin or cresol novolac resin, (3) diglycidyl ether of hydrogenated bisphenol A, (4) glycidyl amine type, (5) linear aliphatic epoxide type, (6)
Examples thereof include diglycidyl ester of phthalic acid, hexahydrophthalic acid or tetrahydrophthalic acid. The epoxy equivalent of these liquid epoxy resins is 100 to 300.
Those of 150 to 250 are particularly preferable.

These liquid epoxy resins may be used alone or in combination of two or more.
Ethylene oxide- or propylene oxide-added bisphenol A for imparting toughness and tackiness to the resulting foam
Type epoxy resin, dimer acid type epoxy resin, modified epoxy resin such as epoxy modified NBR may be used in combination. 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, polymethylmethacrylate or a copolymer resin of methylmethacrylate containing methylmethacrylate as a predominant amount and a copolymerizable monomer such as ethylacrylate or acrylonitrile is used.

The preferred average degree of polymerization of the methacrylic resin is 2 in terms of polymethylmethacrylate.
It is in the range of 000 to 30,000. Average degree of polymerization 2
If it is less than 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 during processing deteriorates and it becomes difficult to obtain a high expansion ratio, and the effect of the present invention decreases, which is not preferable. The methacrylic resin has an average particle size of 300 μm.
m or less, and preferably 1 to 100 μm. If the particle size exceeds 300 μm, the uniform dispersibility with other components will deteriorate. In addition, the amount of the methacrylic resin added is
It is in the range of 10 to 200 parts by weight, preferably 20 to 1 per 100 parts by weight of the liquid epoxy resin as the component (A).
It is 00 parts by weight. If the amount is less than 10 parts by weight, the viscosity at the time of processing becomes too low and the foamed cell may become too low depending on the viscosity of the epoxy resin as the component (A), the properties of the polyethylene resin as the component (C) described later, and the amount added. The cell structure does not become dense due to flow breakage and the like, and if it is added in excess of 200 parts by weight, the meltability during processing deteriorates and a high expansion ratio cannot be obtained.

In the composition of the present invention, a polyethylene resin is used as the component (C). As the polyethylene resin, a copolymer resin with polyethylene or a copolymerizable monomer such as vinyl acetate or propylene containing ethylene as a predominant amount is used. The melt index is 100 or less, preferably 0.5 to 1
00, particularly preferably in the range of 1 to 50. Further, the addition amount is 100 parts of the liquid epoxy resin of the component (A).
10 to 200 parts by weight, preferably 20 to 1 per part by weight
It is in the range of 00 parts by weight. Melt index is 100
If it exceeds, the melt viscosity at the time of processing becomes low, and a dense cell structure is not formed due to flow breakage of the foam cells. In addition,
If the melt index is less than 0.5, the meltability during processing tends to deteriorate and a high expansion ratio tends to be difficult to obtain, which is not preferable. When the amount added is less than 10 parts by weight, the meltability at the time of processing is deteriorated and a high expansion ratio cannot be obtained, depending on the amount added of the component (B) or the degree of polymerization. When it exceeds the weight part, the viscosity at the time of processing becomes too low, and the dense cell structure is not formed due to the flow breakage of the foamed cells and the like, which is beyond the object of the present invention.

The polyethylene resin has an average particle size of 300 μm or less, preferably 1 to 100 μm.
Is. If the average particle size exceeds 300 μm, the dispersibility with other components becomes poor. In the composition of the present invention, (D)
As a component, 0.5 to 20 parts by weight of a latent curing agent for epoxy resin is used. This curing agent preferably has an exothermic peak temperature in the range of 100 to 220 ° C. in combination with an epoxy resin. Examples of such a curing agent include:
Dicyandiamide, 4,4′-diaminodiphenyl sulfone, imidazole derivative such as 2-n-heptadecyl imidazole, isophthalic acid dihydrazide, N, N′-dialkylurea derivative, N, N′-dialkylthiourea derivative, tetrahydroanhydrophthalate Examples thereof include acid anhydrides such as acids, isophoronediamine, m-phenylenediamine, N-aminoethylpiperazine, boron trifluoride complex compounds, and trisdimethylaminomethylphenol.

These hardeners may be used alone or in combination of two or more, and the addition amount thereof is 0.5 per 100 parts by weight of the liquid epoxy resin as the component (A). It is necessary to select within the range of up to 20 parts by weight. If the amount added is less than 0.5 parts by weight, the curing will be insufficient and the elastic modulus of the foam will be low. If the amount added exceeds 20 parts by weight, the elastic modulus of the foam will not improve for that amount, which is rather economical. Be at a disadvantage. Further, in the present invention, together with the curing agent of the component (D), if necessary, for example, alcohol-based, phenol-based, mercaptan-based, dimethylurea-based, alicyclic-based, further imidazole, monuron, chlorotoluene and the like curing acceleration Agents can be used. In the composition of the present invention, the decomposition gas generation temperature is 10 as the component (E).
A blowing agent of 0 to 220 ° C. is used. As such a high temperature decomposition type foaming agent, an organic foaming agent, an inorganic foaming agent, a high temperature expansion type microcapsule or the like can be used. When the decomposition gas generation temperature is less than 100 ° C., foaming starts before being formed into a sheet, the resin does not melt sufficiently at the time of heating and foaming, the gas escapes and the expansion ratio does not increase, or it is difficult to obtain a homogeneous foam. . On the other hand, when the temperature exceeds 220 ° C., the processing temperature of the composition becomes too high and deterioration occurs, which makes it difficult to obtain a foam having good quality.

Examples of the organic foaming agent include azodicarbonamide, p-toluenesulfonyl hydrazide, dinitrosopentamethylenetetramine, 4,4'-oxybisbenzenesulfonyl hydrazide and the like. The decomposition temperature of these organic foaming agents can be arbitrarily adjusted by adding an appropriate amount of urea, a zinc compound, a lead compound or the like. Examples of the inorganic foaming agent include sodium hydrogen carbonate and sodium borohydride, and examples of the high temperature expansion type microcapsules include those in which a low boiling point hydrocarbon is encapsulated with 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 expansion type microcapsules can be used, but organic foaming agents are preferred from the viewpoints of expansion ratio, economical efficiency and the like. . These foaming agents may be used alone or in combination of two or more, and the addition amount thereof is 0.5 to 20 parts by weight with respect to 100 parts by weight of the liquid epoxy resin as the component (A). Selected in a range of parts. Addition amount is 0.
If it is less than 5 parts by weight, the expansion ratio is insufficient, and if it exceeds 20 parts by weight, the expansion ratio does not improve for the added amount,
It is economically disadvantageous.

Further, in order to obtain a dense foam having a uniform foam cell diameter and a rigid cell membrane, it is advantageous that the foaming agent has a small particle diameter, for example, a cell having a diameter of 0.5 mm or less. In order to obtain the diameter, 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 may be used in combination with the foaming agent, if necessary. Examples of the foaming accelerator 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 sulfate salts such as sodium lauryl sulfate and sodium myristyl sulfate, alkyl allylsulfonate salts such as sodium dodecylbenzenesulfonate and potassium dodecylbenzenesulfonate, sodium dioctylsulfosuccinate, dihexylsulfosuccinate. Anionic surfactants such as sulfosuccinate salts such as sodium acid salt, ammonium laurate, fatty acid salts such as potassium stearate, polyoxyethylene alkyl sulfate ester salts, polyoxyethylene alkylallyl sulfate ester salts, and rosinate are preferable. I can mention,
Furthermore, sorbitan monooleate, sorbitan esters such as polyoxyethylene sorbitan monostearate,
Nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers and polyoxyethylene alkyl esters, and cationic surfactants such as cetylpyridinium chloride and cetyltrimethylammonium bromide may also be used. it can.

These surfactants may be used alone or in combination of two or more, and the addition amount thereof is 0.05 to 100 parts by weight of the liquid epoxy resin as the component (A). 5 parts by weight, preferably 0.2 to 3 parts by weight. If the amount added is less than 0.05 parts by weight, the effect of homogenizing the foamed cells will be poor, and if the amount added exceeds 5 parts by weight, not only the added amount will not result in homogenization of the foamed cells, but also the resin. Is not preferable because it lowers the thermal stability of. Further, in the composition of the present invention, in order to adjust the melt viscosity and the affinity between the 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 di-
Phthalates such as 2-ethylhexyl phthalate and dibutyl phthalate, phosphates such as tricresyl phosphate, fatty acid esters such as dioctyl adipate, adipic acid condensate of ethylene glycol, trimellitic acid triester, glycol Known ones such as acid ester, chlorinated paraffin, alkylbenzene and the like 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 and increasing the amount of fillers added. Examples of the diluent include reactive diluents such as butyl glycidyl ether, allyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, versatic acid glycidyl ether, dibutyl phthalate, tricresyl phosphate, and butyl benzyl phthalate. , Acetyl tributyl citrate, aromatic process oil, pine oil,
Mention may be made of non-reactive diluents such as 2,2,4-trimethyl-1,3-pentadiol isobutyrate. These diluents are usually the liquid epoxy resin 1 of the component (A).
It is usually selected in the range of 5 to 150 parts by weight, preferably 10 to 100 parts by weight, per 00 parts by weight.

To the composition of the present invention, thixotropic agents, fillers, pigments and the like may be added as necessary for adjusting coating properties such as processability and viscosity, and for cost reduction. Examples of the thixotropic agent include silicic acid anhydride such as silicic acid anhydride and hydrous silicic acid, bentonite such as organic bentonite, asbestos such as silodex, and organic 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 as the component (A). Examples of the filler include calcium carbonate, mica,
Examples thereof include talc, kaolin clay, celite, asbestos, perlite, baryta, silica, silica sand, scaly 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 additive components used as necessary in predetermined amounts, for example, a planetary mixer, a kneader, and a roll. , 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 decompose the foaming agent and cure the epoxy resin, and the known sol process, calender process, extrusion process, etc. By heat molding, it is possible to obtain an epoxy resin foamed body having a high expansion ratio and dense toughness and heat resistance in the foamed cells, and if necessary, a decomposition temperature of the foaming agent of 100 to 150 ° C. or lower. After making a semi-cure molded body at a relatively low temperature, the composition is attached to a necessary part and then heated at a temperature in the range of 140 to 220 ° C. to decompose the foaming agent and cure the epoxy resin. it can. When the epoxy resin foamable composition of the present invention is applied to a rigidity-imparting material for an outer panel of an automobile, a heat insulating material, etc., first, the above-mentioned semi-cure sheet is prepared, and then cut into a desired shape, and then the rigidity is increased. Adhesion is applied to the heatable area where the function such as the above should be given at the production site, and at the same time it is heated and foamed, and at the same time, the epoxy resin in the composition is reacted and cured to make it adhere more firmly to the adhered area. The most effective method is to develop rigidity.

Further, when the composition of the present invention is applied to an outer panel of an automobile, it can be applied even in a step before electrodeposition coating in a production line, so that 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, it has a wide processing range for curing the epoxy resin that reacts subsequently, and the apparent viscosity of the entire composition when foamed is increased. Since it is maintained in a high state even under heating, the curing reaction can proceed without flowing down even if it is applied to a vertical surface or a ceiling surface, and since the composition contains a thermoplastic resin, Viscosity and adhesion to oil surface metal are significantly improved. The composition of the present invention can also be directly applied to a desired object or can be directly filled into the voids of an object having voids to be processed.

[0019]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Examples 1 to 7 and Comparative Examples 1 to 4 Components of the types and amounts shown in Table 1 were mixed at room temperature with a planetary mixer to prepare a foamable composition,
An unfoamed semi-cured sheet was prepared by applying this to a release paper having a thickness of 2 mm using an applicator and heating it in a hot air circulation oven at 110 ° C. for 90 seconds. Then
This unfoamed semi-cure sheet was attached to a steel plate having a thickness of 0.8 mm, the release paper was peeled off, and heat foaming was performed at 150 ° C. for 30 minutes. Further, in the test for evaluating the rigidity, an unfoamed semi-cure sheet was attached to the above-mentioned steel plate, and then the release paper was peeled off to have a thickness of 150 μm or 30 μm.
An aluminum plate having a thickness of 0 μm was placed, and heat foaming and bonding between layers were performed under the above conditions. The epoxy equivalent of the bisphenol A epoxy resin used was 185. The average particle diameter of the foaming agent azodicarbonamide used was 9 μm. Furthermore, the melt index of polyethylene resin is ASTM D-1238.
It is the value measured under the condition of. Table 2 shows the evaluation results when the surface material was not used, and Table 3 shows the evaluation results when the surface material was used.

Each physical property was determined as follows. (1) Deviation resistance during vertical foaming The composition is molded at a temperature not higher than the decomposition temperature of the foaming agent to form an unfoamed semi-cure sheet, which is placed on a steel plate 70 mm long, 110 mm wide, and 0.8 mm thick. Place it, and after creating a structure with a surface material separately shown on it if necessary,
The degree of deviation generated between the steel plate and the foam when this was fixed vertically and heated and foamed at 150 ° C. for 30 minutes was determined according to the following criteria. The deviation is x. ⊚: x ≦ 1 mm ◯: 1 mm <x ≦ 2 mm, there is some deviation, but there is no practical problem. Δ: 2 mm <x ≦ 5 mm, which is a practical problem depending on the part. X: 5 mm <x, which cannot be put to practical use. XX: Peeling

(2) Rigidity ratio of structure The composition is molded at a temperature not higher than the decomposition temperature of the foaming agent to prepare an unfoamed semi-cure sheet, which is placed on a 0.8 mm thick steel plate and, if necessary, After further forming a structure having a surface material separately shown thereon, heat foaming and adhesion between layers were performed at 150 ° C. for 30 minutes. The mechanical impedance is obtained by vibrating the structure thus obtained, and the resonance frequency is calculated by the mathematical formula shown below according to the amount of movement from the resonance frequency of the 0.8 mm steel plate alone, and the mechanical impedance of 200 Hz is calculated by interpolation. The rigidity ratio was calculated. The measurement frequency is 1 to 1000 Hz, and the measurement temperature is 20, 40, 60 ° C.
Is. Stiffness ratio = (fo / f) ² · {(m ₁ + m ₂ ) / m ₁ } where fo: Resonant frequency of layered structure (Hz) f: Resonant frequency of single steel plate (Hz) m ₂ : Test Area density of body (g / m ² ) m ₁ : Area density of steel sheet alone (g / m ² ). The size of the test body is 30 × 300 mm.

(3) Foaming Ratio, Foamed Cell Shape, and Denseness The foaming ratio was determined by dividing the total thickness of the foamed layer by the thickness of the semi-cure sheet, and the foamed cell shape and denseness were determined according to the following criteria. A: The cells are uniform and dense, and most of them are closed cells. ◯: The cell is relatively uniform and dense, with some open cells. Δ: The cells are relatively nonuniform and coarse, and there are many open cells. ×: cells are non-uniform and rough, mostly open cells,
Or it hardly foams.

[0023]

[Table 1]

[0024]

[Table 2]

The subscripts in Table 1 indicate the following. Note) 1) Polymethylmethacrylate 100% [Average degree of polymerization: 3000, one that has passed through a 250-mesh screen (average particle size: 1 μm)] 2) Polymethylmethacrylate / ethyl acrylate copolymer (composition weight ratio: 90/10, average degree of polymerization: 60
00, that passed through a 250-mesh screen [average particle size: 1 μm)] 3) high-density polyethylene [melt index: 8,
Passed through a 65 mesh screen (average particle size: 1
00 μm)] 4) High-density polyethylene [melt index: 20,
What passed through a 65-mesh screen (average particle size:
100 μm)] 5) Ethylene / vinyl acetate copolymer [composition weight ratio: 94
/ 6, melt index: 7, passed through a 65-mesh screen (average particle size: 100 μm)]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

The epoxy resin-based foamable composition of the present invention can provide a foam having a high expansion ratio and a uniform and dense foam cell diameter, and rigidity and heat resistance. For example, it can be suitably used 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 in the fields of automobiles, home appliances, building materials and the like. In particular, in the field of automobiles, when it is used as a rigidity reinforcing material for a vehicle body outer panel, it is advantageous because it can be applied in a step before the electrodeposition coating step in a production line.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Asako Nouga, 1-2-1, Yokou, Kawasaki-ku, Kawasaki-shi, Kanagawa, Japan Zeon Corporation R & D Center (72) Seiki Yada, Kawasaki-ku, Kawasaki-shi, Kanagawa 1-2-1 Yokou, ZEON Corporation R & D Center, Japan (72) Inventor Toshio Nagase 1-2-1 Yokou, Kawasaki-ku, Kanagawa Prefecture ZEON Corporation R & D Center

Claims (1)

(57) [Claims] 1. A methacrylic resin 10-2 having an average particle diameter of 300 μm or less (B) per 100 parts by weight of a liquid epoxy resin containing one or more epoxy groups in one molecule (A).
00 parts by weight, (C) 10 to 200 parts by weight of a polyethylene-based resin having a melt index of 100 or less and an average particle diameter of 300 μm or less, (D) a latent curing agent for epoxy resin of 0.5 to 20 parts by weight, (E) ) Decomposition gas generation temperature is 10
0.5 to 20 parts by weight of a foaming agent at 0 to 220 ° C. and (F)
An epoxy resin type foamable composition comprising 0.05 to 5 parts by weight of a surfactant.