JPH0588883B2 - - 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, 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 present inventors attempted to acetoacetylate an aromatic secondary amine with a ketene dimer. The model is expressed by the following formula.

[Effect]

The N-acetoacetyl group-containing aromatic acetoacetamide (hereinafter abbreviated as acetoacetamide) of the present invention exhibits an excellent curing accelerating effect as a room temperature curing accelerator for radical curing resins such as polyester resins and vinyl ester resins. Although the reason is not clear, it is presumed that the presence of the N-acetoacetyl group bonded to the nitrogen atom contributes greatly. Acetoacetamide used in the present invention can be easily synthesized by N-acetoacetylation of an aromatic secondary amine with a ketene dimer. There is no need to particularly limit the structure of the aromatic secondary amine used as a raw material, but if the molecular weight is too large, the amount used will inevitably increase, which is not a desirable direction. Examples of aromatic secondary amines suitably used in the present invention include monomethylaniline, monoethylaniline, monobutylaniline, monoethanolaniline, paramethyl N-methylaniline, and benzylaniline. Other aromatic secondary amines such as monomethylnaphthylamines can also be used. In particular, aromatic secondary amines having alcoholic hydroxyl groups can be very useful accelerators since the hydroxyl groups are also acetoacetoxylated. The reaction between an aromatic 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-methylacetoacetanilide 642 g of monomethylaniline was placed in an autoclave.
and nitrogen purge from 3.0Kg/ ^cm2 to 0.2Kg/cm2.
cm ² was repeated three times, the pressure was returned to normal pressure, 529 g of ketene dimer was charged into the dropping funnel, a pressure of approximately 5 kg/cm ² was applied by filling with nitrogen gas, and the pressure was dropped into the autoclave. As the dropwise addition generated heat, the solution was cooled to prevent the temperature from rising above 50°C. After dropping for 2 hours, the mixture was aged for 30 minutes while maintaining the temperature at 45 to 50°C. It was poured into a nitrogen-filled container and solidified. N-methylacetoacetanilide (the following formula), which is a pale yellow needle-like crystal, was obtained in a yield of 99 (%).

[Chemical formula] N-methylacetoacetanilide This will be referred to as accelerator A hereafter. 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] * 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.
After reacting at 130-135℃ for 3 hours with vigorous stirring, the acid value was 9.4, so styrene was initially
g, then pour the contents into 2 beakers and further
250g was added to obtain a vinyl ester resin. It had a Gardner color number of 5 and a viscosity of 5.4 poise. Synthesis of N-acetoacetylxyethyl acetoacetanilide 411g of monoethanolaniline was mixed with 189g of styrene.
(containing 5 ppm of copper naphthenate) and reacted with 570 g of ketene dimer in the same manner as in Example 1 to synthesize N-acetoacetoxyethylacetoacetanilide assumed to have the following formula.

[C] A pale yellow-brown styrene solution, which is used as accelerator B.
And so. To 100 parts of vinyl ester resin, add 1.5 parts of peroxide succinic acid (hardening agent #328 from Kayaku Nouri Co., Ltd.).
%, cobalt naphthenate, and accelerator (B) were respectively added, and the curability was measured 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] * After standing overnight, it remains rubbery and does not cure [Effects of the Invention] The curing acceleration method of the present invention uses an aromatic acetoacetamide containing an N-acetoacetyl group as a curing accelerator, thereby reducing radical Curable 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 aromatic acetoacetamide as a curing accelerating aid in curing the radical curable resin. 2. The method for accelerating curing of a radical curable resin according to claim 1, characterized in that N-methylacetoacetanilide or N-acetoacetoxyethyl acetoacetanilide is used as the aromatic acetoacetamide. 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.