JPH11140212A - Foamable composition based on epoxy resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of providing a foam of uniform and dense foam structure having a high foaming rate by compounding a liquid epoxy resin, an ordinary temperature curing type curing agent, and a water-containing phenolic resin in specific amounts, respectively. SOLUTION: This composition preferably comprises (A) 100 pts.wt. of a liquid epoxy resin, (B) 15-130 pts.wt. of an ordinary temperature curing type curing agent (preferably a water-soluble resol type phenolic resin) and (C) 0.1-60 pts.wt. of a phenolic resin containing water. The composition may further contain (D) a foam stabilizer (preferably a silicone surfactant) and (E) a nucleating agent (preferably calcium carbonate, talc, clay or the like) in amounts of 0.05-5 pts.wt. and 0.1-50 pts.wt., respectively, per 100 pts.wt. of the component A. The content of water contained in the phenolic resin the component C is preferably 1-50 wt.%. Foams produced from the composition can suitably be used e.g. as the interior or exterior materials of automobiles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin foamable composition. More specifically, the present invention relates to an epoxy resin-based foamable composition that can produce an epoxy resin-based foam having a high expansion ratio and a dense cell structure without heating at room temperature.

[0002]

2. Description of the Related Art Epoxy resin has a strong adhesive force, and its cured product has high mechanical strength, chemical resistance, weather resistance,
Because of its excellent electrical insulation properties, it is widely used as a paint, adhesive, electrical insulation material, and the like. More recently, epoxy resins having such favorable properties have been foamed,
BACKGROUND ART In addition to heat insulation, soundproofing, light weight, and the like, they are increasingly used as interior and exterior materials for automobiles, interior materials for vehicles such as aircraft and trains, and materials for civil engineering and construction. In particular, when used as a civil engineering building material, it is desired to produce and apply a foam at room temperature at the work site.

[0003]

Conventionally, as a method for producing an epoxy resin foam, for example, an organic or inorganic pyrolytic foaming agent such as azodicarbonamide or sodium bicarbonate is added to a liquid epoxy resin. A method is known in which foaming and curing are performed in parallel with heating. However,
This method requires heating to decompose the blowing agent,
It cannot be performed at room temperature. Furthermore, in this method, in order to produce a foam having a high expansion ratio and a uniform and dense cell structure, various conditions such as the amount of the foaming agent added, the foaming temperature, and the viscosity of the epoxy resin are optimally adjusted. It has to be in place, but it is very difficult. Accordingly, most of the foams actually obtained have a low expansion ratio and a coarse cell structure.

Further, a method of producing a foam by bubbling an epoxy resin by mechanical stirring has been proposed (US Pat. No. 4,546,118). However, since the bubbles generated by this method are easily broken during the curing process of the epoxy resin, it is difficult to obtain a foam having a high expansion ratio, a dense and uniform cell structure. In addition, in this method, a large amount of an expensive foam stabilizer needs to be added in order to keep generated bubbles in the epoxy resin, so that the cost is increased and industrial implementation is difficult. Furthermore,
U.S. Pat. No. 4,410,639, U.S. Pat.
No. 88, JP-A-60-19033 and the like disclose a method of adding and mixing minute hollow particles to an epoxy resin. However, the addition of the fine hollow particles lowers various physical properties of the epoxy resin, and also lowers the mechanical strength and the like of the obtained foam. In addition, as in the case of foaming by mechanical stirring described above, a large amount of expensive fine hollow particles is added, so that industrial implementation is difficult.

[0005] In addition to the above, for example, an epoxy resin foamable composition containing an epoxy resin, a methacrylic resin, a polyethylene resin, a latent curing agent for epoxy resin, a pyrolytic foaming agent and a surfactant ( JP-A-5-1947
No. 80), an epoxy resin composition containing an epoxy resin, minute hollow particles, a pyrolytic foaming agent and an aromatic diamine (JP-A-4-266939). However, these compositions have the same problems as described above, and do not satisfy the current demand, particularly in that heating for foaming is required. An object of the present invention is to provide an epoxy resin-based foamable composition which does not require heating and can easily produce an epoxy resin-based foam having a uniform and dense cell structure at a high expansion ratio at room temperature.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an epoxy resin containing 100 parts by weight of a liquid epoxy resin, 15 to 130 parts by weight of a room temperature curing type curing agent, and 0.1 to 60 parts by weight of a phenol resin containing water. It relates to a foamable composition.

According to the present invention, in a system using a liquid epoxy resin as a matrix, by using a room temperature curing type curing agent and a phenol resin containing water, curing and foaming occur without heating at room temperature, It has been found that an epoxy resin foam having a uniform and dense cell structure with a high expansion ratio can be easily produced, and the present invention has been completed. The resulting foam retains the properties inherent in the cured epoxy resin, that is, high mechanical strength, excellent heat resistance, weather resistance, electrical insulation, etc., and further excellent heat insulation, sound insulation, etc., and is lightweight. It is. The use of the composition of the present invention makes it possible to produce an epoxy resin foam even at the site of civil engineering work.

[0008] In the composition of the present invention, it is considered that the room temperature curing type curing agent first reacts with the phenol resin and then causes a curing reaction with the epoxy resin. The reaction between the room-temperature curing type curing agent and the phenolic resin increases the viscosity of the composition of the present invention, and provides sufficient conditions for trapping gas generated from moisture contained in the phenolic resin in the matrix epoxy resin. It is considered that a foam having a high foaming ratio and a dense cell structure can be obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the composition of the present invention, a liquid epoxy resin, a room temperature curing type curing agent, and a phenol resin containing water are required as essential components, and it is essential that these essential components are blended in specific amounts. And The liquid epoxy resin is not particularly limited and known ones can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, brominated bisphenol A type epoxy resin,
Room temperature-curable epoxy resins such as hydrogenated bisphenol A type epoxy resin, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin and glycidylamine type epoxy resin can be preferably used. One type of liquid epoxy resin can be used alone, or two or more types can be used in combination.

Known cold-setting curing agents can be used, for example, polymercaptan type, aliphatic amine type, aromatic amine type, alicyclic amine type, modified aliphatic amine type, modified alicyclic amine Mold, polyamide type, ketimine type and the like. Among these, modified aliphatic amine type, modified alicyclic amine type and the like can be preferably used. Specific examples of modified aliphatic amines and modified alicyclic amines include fatty acids such as triethylenetetramine, hexamethylenediamine, tetraethylenepentamine, metaxylenediamine, isophoronediamine, diaminodicyclohexylmethane, and N-aminoethylpiperazine. Modified dimer acids, epoxides and Mannich of aliphatic amines and alicyclic amines can be exemplified.
One of the cold-setting curing agents can be used alone, or two or more can be used in combination. The amount of the room-temperature curing type curing agent is usually 15 to 130 parts by weight, preferably 25 to 65 parts by weight, based on 100 parts by weight of the liquid epoxy resin. If less than 15 parts by weight,
Insufficient curing results in reduced foam strength and reduced foaming ratio. On the other hand, when the amount exceeds 130 parts by weight, the calorific value increases and resin burning occurs, and the balance between curing and foaming is lost, and moldability deteriorates, which is not preferable. Further, it is economically disadvantageous. In addition, tertiary amines, together with a room temperature curing type curing agent,
An appropriate amount of a curing accelerator such as an imidazole derivative or dimethylurea can be used in combination. As the curing accelerator, one type can be used alone, or two or more types can be used in combination.

The phenol resin containing water has a function as a foaming agent as one of its functions in the composition of the present invention. That is, the water contained in the phenol resin is
It is vaporized by the reaction heat during the curing reaction and foams.
However, as described above, without the presence of a room temperature curing type curing agent, since the viscosity of the composition of the present invention is not sufficiently high, outgassing occurs, and only coarse foams can be obtained. It is important to use the drug together.

The water-containing phenol resin is not particularly limited, and any known phenol resin can be used, but a water-soluble resol type phenol resin is preferable. The water-soluble resol-type phenol resin is produced by reacting a phenol compound with an aldehyde compound in the presence of an alkali catalyst. Here, the phenol compound is not particularly limited as long as it is phenol or a homolog thereof, and examples thereof include phenol, cresol, xylenol, p-alkylphenol, p-phenylphenol, and resorcinol. One phenol compound can be used alone, or two or more phenol compounds can be used in combination. The aldehyde compound is not particularly limited as long as it has reactivity with the phenol compound, and examples thereof include formaldehyde, paraformaldehyde, acetaldehyde, furfural, and hexamethylenetetramine. One aldehyde compound can be used alone, or two or more aldehyde compounds can be used in combination. Examples of the alkali catalyst include sodium hydroxide, potassium hydroxide, ammonia, and triethylamine. The amount of water contained in the phenol resin is usually about 1 to 50% by weight, preferably about 5 to 25% by weight.

The amount of the water-containing phenolic resin is usually 0.1% with respect to 100 parts by weight of the liquid epoxy resin.
1 to 60 parts by weight, preferably 5 to 40 parts by weight.
If the amount is less than 0.1 part by weight, the expansion ratio becomes low, and it is difficult to obtain the denseness and uniformity of the cell structure. On the other hand, if the amount exceeds 60 parts by weight, the effect of increasing the expansion ratio is small,
On the contrary, the strength of the foam is reduced, which is economically disadvantageous. In the present invention, a foam stabilizer and a nucleating agent can be further used. As the foam stabilizer, any of those conventionally used in the foaming field can be used, but from the viewpoint of obtaining a foam having a more dense and uniform cell structure,
Silicone surfactants can be preferably used. Examples of the silicone surfactant include L-501 and L-501.
-520, L-530, L-540, L-5320, L
Commercially available under trade names such as -5420 [all manufactured by Nippon Unicar Co., Ltd.], F-114, F-12
1, F-138, F-244, F-305, F-31
7, commercially available under the trade names of F-345 [all manufactured by Shin-Etsu Silicone Co., Ltd.] and the like. One type of foam stabilizer can be used alone, or two or more types can be used in combination. The compounding amount of the foam stabilizer is liquid epoxy resin
The amount is usually 0.05 to 5 parts by weight, preferably 0.1 to 2 parts by weight based on 100 parts by weight. If the amount is less than 0.05 part by weight, the compounding effect is small, and even if the compounding amount exceeds 5 parts by weight,
For that reason, the effect is not improved, and it is uneconomical.

As the nucleating agent, any of those conventionally used in the field of foaming can be used, but from the viewpoint of further improving the uniformity and denseness of the cell structure and further suppressing the shrinkage of the foam. Is, for example, calcium carbonate,
Inorganic fine powders such as talc, clay, mica and silica, and metal salts of fatty acids such as cadmium stearate, zinc stearate, calcium stearate, barium stearate, lead stearate, magnesium stearate and aluminum stearate can be preferably used. . One nucleating agent can be used alone, or two or more nucleating agents can be used in combination. The amount of the nucleating agent is usually 0.1 to 50 parts by weight, preferably 0.5 to 30 parts by weight, based on 100 parts by weight of the liquid epoxy resin. Less than 0.1 part by weight has little effect,
Even if it is added in excess of parts by weight, the effect is little improved, and the viscosity increases, making it difficult to uniformly mix the composition itself.

In order to obtain a foam having a higher expansion ratio in the composition of the present invention, a pyrolytic foaming agent can be used in combination. Examples of the pyrolytic foaming agent include dimethyl azodicarboxylate, diethyl azodicarboxylate,
Azodicarboxylic acid diesters such as diisopropyl azodicarboxylate, inorganic compounds such as sodium bicarbonate and ammonium carbonate, azodicarbonamide, azobisisobutyronitrile, N, N′-dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazide, p, p'-oxybis (benzenesulfonyl hydrazide) and the like can be mentioned. The pyrolytic foaming agents can be used each alone or two or more of them can be used in combination. Among them, azodicarboxylic acid diesters are particularly preferable because they can be easily foamed at room temperature in the presence of water. The azodicarboxylic acid diesters can be produced, for example, by reacting hydrazine hydrate with chlorocarbonate to produce a hydrazodicarboxylic acid ester, which is oxidized with an oxidizing agent such as halogen. Further, when foaming at room temperature using azodicarbonamide, etc., even in the presence of water, zinc oxide, lead oxide, magnesium oxide, zinc carbonate,
It is preferable to use a decomposition accelerator such as barium carbonate in combination. The amount of the thermal decomposition type foaming agent is not particularly limited as long as the room-temperature foamability of the composition of the present invention is not impaired, but is usually up to 5 parts by weight, preferably 0.05, based on 100 parts by weight of the liquid epoxy resin. To 4.5 parts by weight, more preferably 0.1 to 4.5 parts by weight
It is preferably 2.0 parts by weight.

In the composition of the present invention, if necessary,
A reactive diluent for epoxy resin may be added for the purpose of facilitating the mixing of each essential component or optional component or increasing the amount of the nucleating agent. As the reactive diluent for the epoxy resin, any of those conventionally used can be used, and examples thereof include butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, and cresyl glycidyl ether. Can be mentioned. As the reactive diluent for epoxy resins, one type can be used alone, or two or more types can be used in combination. Furthermore, the composition of the present invention may contain additives conventionally used in the field of foaming, for example, plasticizers, stabilizers, cross-linking agents, antioxidants, ultraviolet absorbers, coloring agents, as long as the excellent effects are not impaired. Agents, pigments, flame retardants, reinforcing materials, fillers, optical brighteners, and the like.

The composition of the present invention comprises a predetermined amount of the above essential components,
It can be easily produced by mixing optional components according to a known method, if necessary. The mixing method is not particularly limited, and is, for example, a known mixing method such as a high-speed stirrer (dissolver) having rotating blades or a three-component injection foaming machine equipped with a mixing head used for foaming urethane resin, phenol resin and the like. For example, using a machine for use. In foaming and curing the composition of the present invention, there is no particular need to heat, and the foaming is completed by the heat generated during the curing reaction. When foaming and curing the composition of the present invention at the site of civil engineering work, for example, a continuous injection foaming machine having a mixing head may be used. Since the epoxy resin foam obtained by the present invention has the above-mentioned excellent properties, it can be applied to various uses in a wide range of industrial fields, for example, interior and exterior materials of automobiles, vehicles such as electric trains, and aircraft. It can be suitably used as an interior material for ships, civil engineering construction materials, and the like.

[0018]

EXAMPLES The present invention will be specifically described below with reference to Reference Examples, Examples and Comparative Examples. Reference Example 1 80% hydrazine hydrate 12.5 g and water 200 g
37.8 g of methyl chlorocarbonate and 21.2 g of sodium carbonate were added to the mixture, and the mixture was reacted at 25 ° C. for 2 hours. Then, 200 ml of methylene chloride was added, and chlorine was added at 10 ° C. or lower.
14.2 g were introduced. Next, the methylene chloride layer was separated,
After dehydration with anhydrous magnesium sulfate, concentrated under reduced pressure,
26.3 g of oily dimethyl azodicarboxylate (yield 90)
%). It has a purity of 97% or more and can be used as it is as a foaming agent.

Reference Example 2 In place of methyl chlorocarbonate of Reference Example 1, 43.4 g of ethyl chlorocarbonate was used, and the reaction and post-treatment were carried out in the same manner as in Reference Example 1. 32.0 g of oily diethyl azodicarboxylate was obtained.
(92% yield). This can also be used as it is as a foaming agent. Reference Example 3 In place of methyl chlorocarbonate of Reference Example 1 and using 49.0 g of isopropyl chlorocarbonate, the reaction and post-treatment were carried out in the same manner as in Reference Example 1 to obtain 37.6 g of oily diisopropyl azodicarboxylate (yield 93%). ) Got. This can also be used as it is as a foaming agent.

Examples 1 to 3 Epoxy resins (bisphenol A type epoxy resin, epoxy equivalents 181 to 19) in proportions (parts by weight) shown in Table 1
1), modified alicyclic polyamine (amine value 400 to 48)
0), resole type phenol resin (solid content 80% by weight), silicone-based foam stabilizer [trade name: L-4520, manufactured by Nippon Unicar Co., Ltd.], calcium carbonate (average particle size 3)
μm) and diethyl azodicarboxylate (Reference Example 2)
The mixture was placed in a polypropylene container having a capacity of 1 liter, stirred and mixed with a propeller high-speed stirrer for 1 minute, allowed to stand for 5 minutes to allow the decomposition and curing reaction of the foaming agent, and allowed to reach room temperature.
After cooling, the obtained foam was taken out of the polypropylene container, and the appearance, cell and magnification of the foam excluding the skin layer were examined. The results are also shown in Table 1.

Comparative Examples 1-2 Epoxy resins (bisphenol A type epoxy resin, epoxy equivalents 181-19) at the ratios (parts by weight) shown in Table 1
1), modified alicyclic polyamine (amine value 400 to 48)
0), silicone-based foam stabilizer (trade name: L-4520),
A calcium carbonate (average particle diameter of 3 μm), a foaming agent (diethyl azodicarboxylate or azodicarbonamide) and zinc oxide were placed in a 1-liter polypropylene container, and the same operation as in the following examples was performed to produce a foam. The foaming performance was evaluated. The results are also shown in Table 1.

[0022]

[Table 1]

From Table 1, it is clear that the foams of Examples 1 to 3 have high expansion ratio and uniform and fine foam cells (cell structure). On the other hand, the foams of Comparative Examples 1 and 2 are:
The expansion ratio was low, the foam cells were rough and uneven, and many large cavities were observed. Further, the foam of Comparative Example 1 also had a large discoloration due to burning of the resin.

[0024]

According to the present invention, there is provided an epoxy resin foamable composition which does not require heating, and which can easily produce an epoxy resin foam having a uniform and dense cell structure with a high expansion ratio at room temperature at ordinary temperature. Can be provided.

Claims (2)

[Claims] 1. An epoxy resin foamable composition comprising 100 parts by weight of a liquid epoxy resin, 15 to 130 parts by weight of a room temperature curing type curing agent, and 0.1 to 60 parts by weight of a phenol resin containing water. 2. The composition according to claim 1, wherein 0.05 to 5 parts by weight of a foam stabilizer and 0.1 to 50 parts by weight of a nucleating agent are added to 100 parts by weight of the liquid epoxy resin.