JPH0588884B2 - - 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 cure at room or low temperatures, but if the amount is too large, it may cause problems during boiling tests or during use. There is a tendency for yellowing to occur, seriously impairing 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]

The N-acetoacetyl group-containing aliphatic acetoacetamide (hereinafter abbreviated as acetoacetamide) of the present invention has an excellent curing accelerating effect as a room temperature curing accelerator for radical curing resins such as unsaturated polyester resins and vinyl ester resins. Although the reason for this is not clear, the N- bonded to the nitrogen atom
It is presumed that the presence of an acetoacetyl group contributes greatly. Acetoacetamide used in the present invention can be easily synthesized by N-acetoacetylation of an aliphatic secondary amine with a ketene dimer. Although it is not necessary to particularly limit the structure of the aliphatic secondary amine, one with an excessively large molecular weight inevitably requires a large amount of use, which is not a desirable direction. Examples of aliphatic secondary amines suitably used in the present invention include dimethylamine, diethylamine, diisopropylamine, dibutylamine, diethanolamine, and N-methylaminoethanol. Particularly, aliphatic secondary amines having a hydroxyl group are suitable because the hydroxyl group is also acetoacetoxylated and thus becomes a very useful accelerator. The reaction between an aliphatic secondary amine and a ketene dimer can be easily carried out. 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 acetoacetamide used per 100 parts by weight of these radical curable resins (the same applies hereinafter) is:
The amount 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 hardening accelerators, such as naphthenic acid, octylic acid, etc.
%Co), manganese, vanadine, copper, and other salts. They are used in amounts of 0.01 to 2 parts. 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-methylamino N-acetoacetoxyethylacetoacetamide N-methylaminoethanol in an autoclave

[Formula] 375g, styrene 375g, and copper naphthenate 1ppm (relative to styrene) were charged, and after nitrogen substitution (applying 3.0Kg/cm and reducing the pressure to 0.2Kg/ ^cm2 ) three times,
1024 g of ketene dimer was charged into a closed dropping funnel, and the internal pressure in the funnel was adjusted to about 5 kg/cm ² with nitrogen gas, and the mixture was added dropwise to N-methylaminoethanol in an autoclave over about 2 hours. At the same time as dropping, heat is generated, so the reaction temperature is 50℃
I kept it below. After dropping the ketene dimer (it takes about 2 hours), maintain the temperature at 50 to 60℃ for 30 minutes, then return to normal pressure.
The contents were placed in a sealed container and cooled. A pale yellowish brown liquid with the following formula:

A styrene solution of the compound N-methyl N-acetoacetoxyethyl acetoacetamide was obtained. The structure of the above formula was deduced from the results of infrared analysis and NMR analysis. The yield was 99 (%) and quantitative. This was designated as the accelerator (A). Synthesis of unsaturated polyester resin [] 161 g of propylene glycol, 196 g of maleic anhydride, and 296 g of phthalic anhydride were placed in a separable flask equipped with a stirrer, a fractionating condenser, a gas inlet tube, and a thermometer, and the mixture was placed in a nitrogen gas stream. 180～
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】

[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 trimethylbenzylammonium chloride, and reacted at 130 to 135°C with vigorous stirring for 3 hours. The acid value was 9.4, so 300 g of styrene was initially added, and then 250 g of the contents were 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. For 100 parts of vinyl ester resin, peroxide succinic acid (#hardening agent 328 from Kayaku Nouri Co., Ltd.)
Add 1.5 parts of cobalt naphthenate and N,N'-dimethylacetoacetamide (the following formula, hereinafter referred to as accelerating aid (B)) as a promoting aid, respectively.

[Formula] Curability was measured. For comparison, acetylacetone was used as a curing accelerator and the same measurement was performed. The results shown in Table 2 were obtained, and an excellent promoting effect was confirmed.

[Table] * No curing in rubber state after standing overnight [Effects of the invention] The curing acceleration method of the present invention uses an N-acetoacetyl group-containing aliphatic acetoacetamide as a curing accelerator. Therefore, radical curing resin can be completely cured in a short time without yellowing at or near room temperature, and there is no deterioration in the physical properties of the cured molded product, so FRP,
It is extremely useful in the field of room temperature curing such as paints, linings, and casting.

Claims (1)

[Scope of Claims] 1. A method for accelerating the curing of a radical curable resin, which comprises using aliphatic acetoacetamide as a curing accelerating aid in curing the radical curable resin. 2 As aliphatic acetoacetamide, N,
Claim 1 characterized in that N'-dimethylacetoacetamide or N-methyl N-acetoacetoxyethyl acetoacetamide is used.
A method for accelerating the curing of a radical curable resin as described in 2. 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.