JPS6359409B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an epoxy resin composition that provides a cured product with excellent gasohol resistance. More specifically, an epoxy resin composition containing N,N,N',N'-tetraglycidyl metaxylylene diamine as an epoxy resin component and a product obtained by reacting phenols, formaldehyde, and polyamines as a curing agent. and this composition is
It has a long pot life, can be cured at room temperature, and the cured product exhibits excellent mechanical strength and heat resistance. Traditionally, it is room temperature curable, wet surface adhesive,
Epoxy resin compositions that provide cured products with excellent properties such as surface gloss, chemical resistance, and water resistance are known. Such room temperature curable epoxy resin compositions are used for various purposes such as paints, floor coating materials, and civil engineering adhesives.Epoxy resins include the so-called epi-bis type obtained from bisphenol A and epichlorohydrin. Epoxy resins are used, and so-called Manitzsch type compounds obtained by reacting phenols, formaldehyde, and polyamines are usually used as curing agents. Manizhi type curing agents are suitably used for the above applications because the polyamines are modified, which suppresses whitening due to carbon dioxide absorption, reduces toxicity, and provides good workability. , epi-bis type epoxy resin,
It is generally highly viscous or solid at room temperature, and therefore has poor workability when blending various additives such as extenders, fillers, reinforcing materials, and hardening agents, or requires degassing after blending and mixing. There are many inconveniences, such as the work being extremely difficult. To solve this problem, reactive diluents such as styrene oxide, butyl glycidyl ether, diglycidyl ether, phenyl glycidyl ether, etc. or non-reactive diluents such as dibutyl phthalate, dioctyl phthalate, etc. are used in combination. However, attempts have also been made to lower the viscosity of epoxy resins to make them easier to handle. However, in this case, it is inevitable that the heat resistance, chemical resistance, etc. of the cured product will be significantly impaired. As an epoxy resin other than epi/bis type,
Phenol/novolac type epoxy resins and alicyclic compound type epoxy resins are known, but the former are highly viscous or solid at room temperature, and have the same disadvantages as the epi/bis type epoxy resins mentioned above. In addition, since the pot life after mixing with a curing agent is very short, it cannot be practically used in applications that take advantage of room temperature curability.
On the other hand, although the latter has a low viscosity, when it is cured at room temperature using an amine type curing agent or a Manitzsch type curing agent, the reaction is extremely slow and it cannot be used practically. However, recently, there has been a strong emergence of epoxy resins that can be applied to paints, floor coatings, and adhesives by curing at room temperature, and have a high level of performance that provides cured products with excellent heat or chemical resistance. As one of the reasons behind this, the following demands are becoming apparent. In other words, as is well known, in recent years the use of so-called gasohol, a mixture of gasoline and alcohol, as a fuel for automobiles has been closed due to the oil situation in which oil prices have soared and crude oil production has been curtailed in oil-producing countries. - Plans are being made for its practical use in countries around the world, including West Germany, and there is evidence that mixed fuel containing ethanol is already being used for automobiles in Brazil. It is clear that when gasoline is replaced with gasohol, a new problem will arise in that plastic parts used in fuel tanks, carburetors, fuel pumps, etc. will swell due to contact with gasohol and become unusable. It became. In addition, the gasohol resistance of painted parts or lined floors of refueling equipment at gasoline filling stations is also a serious problem. Overcoming these new problems is becoming an important social requirement. Incidentally, as mentioned above, room temperature curable epoxy resin compositions using bis-epi type epoxy resin are used for various purposes such as paints, floor lining agents, adhesives, etc. However, they have poor tolerance to alcohols such as methanol or ethanol. The inventors of the present invention have carried out intensive studies in view of the above circumstances and requests. As a result, the present inventors have found that the present inventors have developed a material that is room temperature curable, has a low viscosity, has good handling and workability, and has various properties, especially gasohol resistance. An epoxy resin composition has been discovered that provides an excellent cured product. That is, the present invention uses N,N,N',N'-tetraglycidyl metaxylylene diamine as an epoxy resin component, and contains a Mannitz type compound obtained by reacting phenols, formaldehyde, and polyamines as a curing agent. This is an epoxy resin composition. N used in the epoxy resin composition of the present invention,
N,N',N'-tetraglycidylmethaxylylenediamine has the structural formula means a tetrafunctional amine-based epoxy compound represented by The compound is produced from metaxylylene diamine and epihalohydrin (see, for example, Japanese Patent Publication No. 14211/1983), but the product may contain a small amount of dimerization or trimerization of the compound as a by-product. It may happen. N,N,N',N'-tetraglycidyl metaxylylene diamine containing such by-products can also be used without problem for the purpose of the present invention. N, N, N′ used in the present invention,
N′-tetraglycidyl metaxylylene diamine usually has a low viscosity of 15 to 25 poise at 25°C, so it is easy to handle and has good workability, and it can be used in various applications such as extenders, fillers, and reinforcing materials. Additives can be mixed in large quantities. Manitzuch type compounds obtained by reacting phenols, formaldehyde and polyamines used as curing agents are known per se, and can be produced, for example, by the method disclosed in Japanese Patent Publication No. 48-25759. Compound represented by the following general formula () (In the formula, n is 1 to 3, R ¹ is an alkyl group having 1 to 12 carbon atoms, and R ² is a group represented by the following general formula, for example.

【formula】

[Formula] −(CH ₂ ) ₂ NH (CH ₂ ) ₂ −, −(CH ₂ ) ₂ NH(CH ₂ ) ₂ NH(CH ₂ ) ₂ −,

[Formula] is also included. In the Manitzhi type compound, the phenols have the general formula () (wherein R ¹ is an alkyl group having 1 to 12 carbon atoms), such as phenol, p-
Tert-butylphenol, nonylphenol, dodecylphenol, cresol, etc. are used.
Polyamines have the general formula () NH ₂ −R ² −NH ₂ () (wherein R ² is, for example, a group represented by the following general formula).

【formula】

[Formula] −(CH ₂ ) ₂ NH (CH ₂ ) ₂ −, −(CH ₂ ) ₂ NH(CH ₂ ) ₂ NH(CH ₂ ) ₂ −,

[Formula] For example, xylylenediamine, bis(aminomethyl)cyclohexane, isophoronediamine,
Diethylenetriamine, triethylenetetramine, 4,4'-diamino-diphenylmethane, etc. are used. Two or more types of phenols and polyamines may be used. As the formaldehyde, an aqueous formaldehyde solution or paraformaldehyde may be used as appropriate. In the epoxy resin composition of the present invention, the Manitzsch type compound as a curing agent contains active hydrogen per equivalent of epoxy group in N,N,N',N'-tetraglycidyl metaxylylene diamine, similar to the formulation in conventional epoxy resins. Generally, it may be used in an amount such that 1 equivalent of is present. However, depending on the pot life and curing time required of the epoxy resin composition, or the performance required of the cured product, the amount of the Manitzsch type compound used may be adjusted as appropriate. As already known, N, N, N′,
N'-tetraglycidyl metaxylylene diamine can be easily mixed with aliphatic and aromatic polyamines or acid anhydrides commonly used as curing agents for epoxy resins, and has a high heat distortion temperature and excellent mechanical properties when heated. (See, for example, Japanese Patent Publication No. 52-18757 and No. 52-18758). These known N,N,N',N'-tetraglycidyl metaxylylene diamine-containing epoxy resin compositions are generally intended to be cured by heating to obtain a cured product with desired high performance. It was hot. On the other hand, as mentioned above, the epoxy resin composition of the present invention has a low viscosity, so it has good workability in that it can be easily mixed and defoamed at room temperature, and in addition, it is resistant to gelation. The time it takes to reach this point, that is, the pot life, is longer than the conventional epi-
It is longer than when using screw-type epoxy resin, and is room temperature curable, for example, 21
When cured at ℃ for 7 days, a cured product with sufficient specified performance is obtained.
Performance can be further improved by post-curing at relatively low temperatures and short periods of time, such as 120° C. for 20 minutes. Thus, the epoxy resin composition of the present invention
By curing it at room temperature, a cured product that exhibits excellent mechanical properties and heat resistance, and has excellent gasohol resistance can be obtained. It is suitably used for various purposes. The epoxy resin composition of the present invention may contain other epi-bis type, novolac type or amine type epoxy resins as desired, as well as reactive or non-reactive diluents, flexible Additives such as imparting agents, extenders, fillers, and reinforcing materials may be appropriately blended. The present invention will be specifically explained below using reference examples, comparative examples, and examples. Reference Example 141 g of phenol, 81 g of 37% formalin and 4 g of metaxylylene diamine were placed in a 500 ml separable flask, and after refluxing for 2 hours, 200 g of metaxylylene diamine was added dropwise.
After the dropwise addition was completed, the mixture was refluxed for an additional hour, and the temperature was raised to distill water off. The reaction was terminated when the temperature of the contents of the flask reached 170°C. All reactions were conducted in a nitrogen gas stream. The reaction product obtained was a Manizuch type compound having the following characteristic values. Viscosity (25℃) 100 poise, all amines
477, active hydrogen equivalent 70.8, color pale yellow. Example 1 100g of N,N,N',N'-tetraglycidyl metaxylylene diamine and curing agent synthesized in Reference Example
After mixing 71 g and thoroughly stirring with a mixer, the mixture was defoamed under reduced pressure in a filter bell. The obtained resin mixture was placed in a 18 mmφ x 180 mm test tube up to 100 mm from the bottom, and the time until curing heat generation was determined. 0.8 of its value
Table 1 shows the results. Next, the resin mixture was poured between two Teflon plates using a silicone rubber tube as a spacer to form a casting plate. The plate was adjusted to have a thickness of 3 mm. After leaving it in a room at 21°C for 7 days, the cured casting plate was taken out. Cut out 50 mm square test pieces from this casting plate, and cut out 50 mm square test pieces for ethanol, methanol, and gasoline/ethanol (=
85/15 weight ratio) mixture and gasoline/methanol (=85/15 weight ratio) mixture for 4 weeks, and the weight increase before and after immersion was determined. For another test piece, heat distortion temperature, bending strength, bending elastic modulus,
Rockwell hardness was measured. The respective results are also shown in Table 1. Example 2 The same procedure as in Example 1 was carried out using 90 g of N,N,N',N'-tetraglycidyl metaxylylene diamine, 10 g of epi-bis type epoxy resin (epoxy equivalent: 190), and 67 g of the curing agent synthesized in the reference example. The pot life of the resulting resin mixture and the physical properties of the cast plate obtained by casting and curing were measured. The results are also listed in Table 1. Examples 3 and 4 Using the resin mixtures obtained in Examples 1 and 2, casting plates were molded in the same manner as in Example 1. The hardening is
Pretreatment was carried out at 21°C for 4 days, followed by post-curing at 120°C for 20 minutes. The physical properties of the obtained casting plate are also listed in Table 1. Comparative Examples 1 and 2 100 g of the epi-bis type epoxy resin used in Example 2 was mixed with 37 g of the curing agent synthesized in Reference Example. The operation was the same as in Example 1, and the pot life of the resulting resin mixture and various physical properties of the cast plate obtained by casting and curing were measured (Comparative Example 1). The resin mixture was cured under the same conditions as in Example 3, and the physical properties of the resulting casting plate were measured (Comparative Example 2). The respective results are also listed in Table 1.

【table】

Claims (1)

[Scope of Claims] 1 N,N,N',N'-tetraglycidyl metaxylylene diamine as an epoxy resin component, containing a product obtained by reacting phenols, formaldehyde and polyamines as a curing agent. An epoxy resin composition that provides a cured product with excellent gasohol resistance. 2 The product has the general formula () (In the formula, n is 1 to 3, R ¹ is an alkyl group having 1 to 12 carbon atoms, and R ² is, for example, a group represented by the following general formula [Formula] [Formula] -(CH ₂ ) ₂ NH (CH ₂ ) ₂ −, −(CH ₂ ) ₂ NH(CH ₂ ) ₂ NH(CH ₂ ) ₂ −,
The composition according to claim 1, which is represented by the formula: