JPH0588882B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is applicable to bathtubs, reinforced plastics (hereinafter abbreviated as FRP) using glass fiber as a reinforcing material.
Housing-related products such as septic tanks, marine-related products such as fishing boats, yachts, and boats, plant-related products such as pipes and tanks, and non-FRP products such as paint, lining, casting,
This invention relates to a method for accelerating the curing of radical curing resins, which has been put to practical use in a wide range of applications such as decorative boards and laminates. [Prior Art] For radical curing resins such as unsaturated polyester resins and vinyl ester resins, a means for curing them using a radical generator and a curing accelerator in combination is well known and widely used. In recent years, there has been an increasing demand for improving the appearance of cured molded products by making the color as light as possible, regardless of whether they are FRP or non-FRP. For example, when manufacturing a marble-like thick-walled cast bathtub, cobalt organic acid salts are used as hardening accelerators to harden at room temperature to low temperatures, but if the amount is large, it may cause problems during boiling tests or during use. There is a tendency for yellowing to occur, which seriously impairs the appearance. On the other hand, if the amount is small, curing will not proceed at room temperature. A similar phenomenon is true for light-colored paints and decorative boards. In other words, when trying to cure a radical-curing resin at room temperature or a temperature close to this temperature, the use of an organic acid salt of cobalt is unavoidable. The only way to do this is to use a reduced amount of cobalt salt, and it is essential that there be no prolongation of the curing time or deterioration of the physical properties of the molded product. However, at present, a satisfactory solution to this requirement has not yet been found. [Problems to be Solved by the Invention] The present invention eliminates the drawbacks of conventional curing agent systems as described above, and solves the problems that occur when radical curing resins are cured at room temperature or a temperature close to it. It prevents discoloration and completely cures in a short time.
Moreover, it is an object of the present invention to provide a method for accelerating the curing of radical-curable resins, which does not cause any deterioration in the physical properties of the cured molded product. [Means for Solving the Problems] In order to solve the above problems, the present inventors attempted several studies, but in the end, the model was expressed by the following equation.

[Effect]

Although it is not clear why the N-acetoacetyl group-containing heterocyclic compound of the present invention exhibits an excellent curing accelerating effect as a room temperature curing accelerator for radical curing resins such as unsaturated polyester resins and vinyl ester resins. , it is presumed that the presence of the N-acetoacetyl group bonded to the nitrogen atom contributes greatly. The N-acetoacetyl group-containing heterocyclic compound used in the present invention can be easily synthesized by N-acetoacetylating a heterocyclic secondary amine with a ketene dimer. Although there is no need to particularly limit the structure of the heterocyclic secondary amine, one with too large a molecular weight will inevitably require a large amount to be used, which is not a desirable direction. Examples of heterocyclic secondary amines suitably used in the present invention include the following types. Morpholine, piperidine, N-methylpiperazine, piperazinepyrrole, ethyleneimine, pyrrolidine, azetidine, 2-pyrroline, pyrazole, pyrazoline, pyrazolidine, anabasine, 4
-Imidazoles including methylimidazole, indoles, carbazoles, and indazoles. In particular, those using morpholine as a raw material are suitable because the cured resin has a good hue. The radical curable resins to which the present invention is applied are unsaturated polyester resins and oligoacrylates typified by vinyl ester resins. Unsaturated polyester resin contains an α-β unsaturated polybasic acid as an essential component, and can be obtained by esterifying it with a polyhydric alcohol, with or without any saturated or unsaturated polybasic acid. It is obtained by dissolving a saturated alkyd in a copolymerizable vinyl monomer, and there is no need to place any particular restrictions on its composition. Oligoacrylates can be divided into the following types: Vinyl ester resin, urethane to acrylate, polyester to acrylate. However, from a practical standpoint, vinyl ester resin is mostly used. Vinyl ester resins are usually obtained by reacting epoxy resins with (meth)acrylic acid, and styrene is used in combination as a monomer in room temperature curing systems used in the corrosion resistance field. Although the type of epoxy resin is not specified, bisphenol type and novolak type account for most in practical use. Urethane to acrylate is obtained by reacting an unsaturated alcohol having a (meth)acryloyl group with a diisocyanate in the presence or absence of any polyhydric alcohol, polyether, or polyester. Polyesters to acrylates are synthesized by direct esterification of (meth)acrylic acid, saturated or unsaturated polybasic acids, or their acid anhydrides, and polyhydric alcohols. The amount of the curing accelerator used per 100 parts by weight (the same applies hereinafter) of these radical curable resins is 0.01 part or more and 10 parts or less, preferably 0.1 part or more and 1 part or less. The organic peroxide used as a curing agent in the present invention is a commonly used one, and 0.5
It is used in the range of 1 part or more and 3 parts or less. In addition, organic acid salts of metals are suitable as curing accelerators, such as salts of cobalt, manganese, vanadine, copper, etc. such as naphthenic acid and octylic acid, which are used in an amount of 0.01 part or more and 2 parts or less. . Other metal organic acid salts may be used freely. The curing acceleration method according to the present invention is useful in the field of room temperature curing of radical curable resins, for example, in the fields of FRP, paints, linings, and casting. Moreover, it goes without saying that reinforcing materials, fillers, colorants, mold release agents, polymers, etc. can be used in combination as necessary. [Example] Next, in order to assist in understanding the present invention, examples are shown below. Example 1 Synthesis of N-acetoacetylmorpholine 609 g of morpholine was placed in an autoclave.
After performing nitrogen substitution (3.0 Kg/cm ² and pressure reduction to 0.2 Kg/cm ² ) three times, 617 g of ketene dimer was charged into a closed dropping funnel, and the internal pressure in the funnel was adjusted to approximately 5 Kg/cm ² using nitrogen gas. The mixture was added dropwise to morpholine in an autoclave over about 2 hours. Since heat generation was observed when the ketene dimer was added dropwise, the reaction was carried out while cooling to a reaction temperature of 60±3°C. After dropping the ketene dimer, the temperature was maintained at 60°C for 30 minutes, and then the temperature was returned to room temperature and the contents were poured into a sealed container and solidified. A pale yellow crystal with a melting point of 35°C was obtained, and as a result of elemental analysis, it was determined to be a compound of the following formula. The yield is
It was 98.7 (%).

[Chemical] N-acetoacetylmorpholine (hereinafter abbreviated as accelerator A) Synthesis of unsaturated polyester resin [ ] In a separable flask equipped with a stirrer, fractionation condenser, gas inlet tube, and thermometer, 161 g of propylene glycol, Prepare 196g of maleic anhydride and 296g of phthalic anhydride and heat to 180~ in nitrogen gas stream.
After esterifying at 205℃ to form an unsaturated alkyd with an acid value of 36.1, 0.1 g of hydroquinone and 385 g of styrene were added to create an unsaturated polyester resin.
was manufactured. It had a Hazen color number of 150 and a viscosity of 5.1 poise. 100 parts by weight of this resin (the same applies hereinafter), 1 part of methyl ethyl ketone peroxide, cobalt naphthenate (6% Co), and accelerator A were added and cured at 25°C based on the JIS method. The sex was measured. As shown in Table 1, the accelerator A showed an extremely good curing accelerating effect.

[Table] * Example 2 of curing after standing overnight 2 Synthesis of vinyl ester resin [1] Equipped with a stirrer, reflux condenser, and thermometer
A separable flask was charged with 550 g of Epicote #1001 from Yuka Ciel Co., Ltd. as an epoxy resin, 86 g of methacrylic acid, 0.5 g of hydroquinone, and 2 g of trimethylbendial ammonium chloride, and heated to 130-135°C for 3 hours with vigorous stirring. After the reaction, the acid value was 9.4, so 300 g of styrene was added initially and then an additional 250 g was poured into two beakers to obtain a vinyl ester resin. It had a Gardner color number of 5 and a viscosity of 5.4 poise. N-acetoacetylpiperidine (promoter) obtained by adding 1.5 parts of succinic peroxide (328 from Kayaku Nouri Co., Ltd.) to 100 parts of vinyl ester resin, and 617 parts of diketene to 590 parts of piperidine. Agent B) was added, and the curability was examined in the same manner as in Example 1. For comparison, a similar study was conducted using acetylacetone as a curing accelerator. The results shown in Table 2 were obtained.

[Table] *Example 3 which did not cure in a rubber state after one night 3 N-acetoacetylpyrrolidine obtained by similarly converting pyrrolidine into acetylacetonate with a ketene dimer was added to the unsaturated polyester resin [ ] used in Example 1. This was used as the accelerator (C). 100 parts of resin, 1 part of methyl ethyl ketone peroxide, cobalt naphthenate (6% Co)
When the curing properties were measured by changing the amount of accelerator and accelerator (C),
The results shown in Table 3 were obtained, and it was confirmed that N-acetoacetylpyrrolidine had an excellent hardening accelerating effect.

〔Effect of the invention〕

The curing accelerating method of the present invention uses an N-acetoacetyl group-containing heterocyclic compound as a curing accelerating auxiliary agent, so that the radical curing resin can be cured in a short period of time without yellowing at or near room temperature. Since it can be completely cured at room temperature and there is no deterioration in the physical properties of the cured molded product, it is extremely useful in the field of room temperature curing such as FRP, paints, linings, and casting.

Claims (1)

[Scope of Claims] 1. A radical characterized in that a heterocyclic compound having an N-acetoacetyl group bonded to a nitrogen atom in a heterocycle is used as a curing accelerator when curing a radical-curable resin. Method for accelerating curing of curable resin. 2. The method for accelerating curing of a radical curable resin according to claim 1, characterized in that N-acetoacetylmorpholine, N-acetoacetylpiperidine, or N-acetoacetylpyrrolidine is used as the heterocyclic compound. 3. The radical curing type according to claim 1 or 2, characterized in that a vinyl ester resin obtained by reacting an unsaturated polyester resin or an epoxy resin with (meth)acrylic acid is used as the radical curing resin. Method for accelerating curing of resin.