JPS6410535B2 - - Google Patents

Description

[Detailed description of the invention]

[] BACKGROUND TECHNICAL FIELD OF THE INVENTION The present invention relates to a composition comprising a melamine group-containing thermosetting resin that has thermosetting properties due to polymerization of ethylenically unsaturated bonds. Melamine resin has high hardness, high flame retardancy and heat resistance, and also has excellent electrical properties such as arc resistance and tracking resistance, so it has a wide range of uses such as decorative boards, electrical parts, tableware, etc. . Melamine resins, like phenolic resins and urea resins, are produced by a condensation reaction between melamine and formaldehyde. However, this manufacturing method has environmental and energy consumption problems, such as formalin gas odor during reaction, high temperature and pressure required for reaction, and insufficient storage stability before heat curing. There are drawbacks. Prior Art Attempts are known to impart thermosetting properties to resins and to use addition polymerization of ethylenically unsaturated bonds instead of relying on methylolation and methylenation with formaldehyde for thermosetting. For example, an alkyl ether derivative of methylolmelamine is transetherified with a hydroxyalkyl (meth)acrylate to introduce an ethylenically unsaturated bond (U.S. Patent No.
3920255). Although it is not necessarily clear what kind of compound is obtained in this case, it is presumed that hydroxyalkyl (meth)acrylate is bonded to the methylol group of methylolmelamine through an ether bond because of transetherification. be done. There is also a product in which ethylenically unsaturated bonds are introduced by the reaction of methylolmelamine (or its alkyl ether derivative) and hydroxyalkyl (meth)acrylate (British Patent No. 628150).
(see specification). Although it is not necessarily clear what kind of compound is obtained in this case, it appears that hydroxyalkyl (meth)acrylate is bonded to the methylol group of methylolmelamine via an ether bond. However, according to the knowledge of the present inventors, cured products obtained by thermally polymerizing these materials tend to easily swell in hot water and turn white. It also appears to have low heat resistance and rigidity. [] Summary of the Invention The purpose of the present invention is to provide a solution to the above-mentioned problems, and in order to provide thermosetting properties through ethylenically unsaturated bonds, a specific melamine group-containing (meth)acrylate is used as a thermosetting resin. The aim is to achieve this purpose by using Therefore, the thermosetting resin composition according to the present invention is
Containing a melamine group-containing (meth)acrylate represented by the following formula () and a polymerization initiator;
It is characterized by: In the formula, R is a methyl group, a phenyl group,

[Formula] or an organic group represented by the following formula. Y each represents hydrogen or Z ¹¹ . Z ¹ to Z ¹¹ are each - CH ₂ OCOCR ¹ = CH ₂ or - CH ₂ OR ²
shows. At least one of the existing Z ¹ to Z ¹¹ is -CH ₂ OCOCR ¹ =CH ₂ . R ¹ each represents hydrogen or a methyl group, and R ² has 1 to 4 carbon atoms.
represents an alkyl group. Effect: Because imparting thermosetting properties and heat curing are not dependent on methylolation and methyleneation using formaldehyde, and because they can be carried out to the extent necessary to prevent the polymerization of ethylenically unsaturated bonds introduced for imparting thermosetting properties. , the various problems observed in the conventional melamine resins described above have been solved. When the melamine group-containing thermosetting resin in the composition of the present invention is cured by polymerization of ethylenically unsaturated bonds either by itself or dissolved in an ethylenically unsaturated monomer such as styrene, the melamine group-containing thermosetting resin To provide a resin having the above properties or appropriately combining the properties with the properties specific to unsaturated polyester resins. While conventional melamine resins generally require the presence of fillers during curing, curing of the resins produced by the present invention does not necessarily require the presence of fillers. Furthermore, curing can be performed at room temperature. The thermosetting resin used in the composition of the present invention is understood to correspond to a compound obtained by esterifying the methylol group of a methylolmelamine compound with acrylic acid (or its α-lower alkyl substituted product).
Therefore, this thermosetting resin is different from the above-mentioned two known compounds in which a (meth)acrylic acid moiety is bonded to a methylol group via an ether bond. In addition, while the resin production reaction in the two known examples above consists of transetherification, the reaction in the present invention involves destruction of an ether bond and formation of an ester bond, and the two inventions are different in the content of the reaction. ing. However,
It may be said that it was unexpected that an alkyl ether derivative of a methylolmelamine compound could form such an ester compound by reaction with acrylic acid (or its α-lower alkyl substituted product). Moreover, in the cured thermosetting resin composition of the present invention, the structure of the raw material acrylate having a melamine skeleton is similar to that of the acrylate having a melamine skeleton shown in the above-mentioned known literature. Regardless, it has the advantage of excellent hot water resistance and heat-resistant rigidity. [] Detailed Description of the Invention 1 Thermosetting Resin The thermosetting resin used in the composition of the present invention is a melamine group-containing (meth)acrylate represented by the above formula (). Here, "(meth)acrylate" means acrylate or methacrylate. This resin can be produced by reacting an alkyl etherified melamine compound of the following formula (A) with (meth)acrylic acid. (1) Alkyl etherified melamine compound This compound is represented by the following formula (A). In the formula, R′ ¹ each represents a hydrocarbon group having 1 to 4 carbon atoms, and R represents a methyl group, a phenyl group,
-N(CH ₂ OR′ ¹ ) ₂ (R′ ¹ is a hydrocarbon group having 1 to 4 carbon atoms, which is the same as or different from R′ ¹ above),
Or it represents an organic group represented by the following formula. (Y is -CH ₂ OR' or hydrogen, R' ¹ is the same or different carbon number from 1 to 4 as R' ¹ above, respectively.
hydrocarbon group). The alkyl etherified melamine compound represented by the general formula (A) has already been industrially produced in large quantities and is widely used mainly in the paint field as a crosslinking agent for various alkyds, acrylic polymers, etc. , is easily available. Some specific examples of this alkyl etherified melamine compound are as follows. Hexamethoxymethylmelamine, pentamethoxymethylmelamine, tetramethoxymethylmelamine, trimethoxymethylmelamine, tributoxymethylmelamine, hexaethoxymethylmelamine, pentaethoxymethylmelamine, tetraethoxymethylmelamine, trimethoxymethyl-diethoxymelamine, triethoxy Methyl-dibutoxymethylmelamine, hexapropoxymethylmelamine, tripropoxymethylmelamine, dibutoxymethylmelamine, trimethoxymethylmelamine, dipropoxymelamine, hexaptoxymethylmelamine, monomethoxymethylmelamine, tetrabutoxymethylmelamine, tetramethoxymethyl Melamine, methylguanamine, dimethoxymethylguanamine, dibutoxymethylguanamine, methylguanamine,
Monomethoxymethylguanamine, tripropoxymethylguanamine, methylguanamine,
Tetramethoxymethylguanamine, benzoguanamine, tetrabutoxymethylguanamine, benzoguanamine, tetrabutoxymethylguanamine, methylguanamine, dimethoxymethylguanamine, dibutoxymethyl-benzoguanamine, and mixtures thereof. Particularly suitable for the present invention are formula (A) in which R' ¹ is a methyl group and R is -N
(CH ₂ OCH ₃ ) ₂ or phenyl group. In addition, when R′ of the compound represented by general formula (A) is hydrogen, the self-condensation reaction of the compound represented by general formula (A) takes priority in the presence of an esterification catalyst such as p-toluenesulfonic acid. This is not preferred because the reaction between this compound and the acrylic compound becomes rate-limiting. (2) Acrylic compound The acrylic compound in which the alkoxy group (R′ ¹ O) of the compound of formula (A) should be changed into an alkenylcarbonyloxy group is acrylic acid or methacrylic acid. Mixtures of both can also be used. (3) Reaction The reaction that produces the compound of formula () converts the alkyl ether of the methylol compound of the melamine compound of formula (A) into the acrylic acid (or its α-lower alkyl substituted product) ester of this methylol compound. It is understood that it consists of This reaction should esterify at least one of the etherified methylol groups. The theoretical upper limit for esterification would be equal to the number of methylol groups in compound (A). The reaction can be carried out without using a solvent. Although this is usual, it can also be carried out in the presence of a suitable solvent or dispersion medium if desired. Examples of the solvent or dispersion medium in this case include those inert with respect to the reaction, such as hydrocarbons such as toluene and xylene, and halogenated hydrocarbons such as chlorobenzene. The molar ratio of the acrylic acid compound and the alkyl etherified melamine compound (A) is 1/1 to 6/1.
It is usually about 2/1 to 4/1, preferably about 2/1 to 4/1. The specific molar ratio is the compound
It will be determined by the number of moles of acrylic acid compound bound to (A). The reaction temperature is about 50 to 150℃, preferably 100℃
The temperature is usually around 130°C.
The reaction time varies depending on the distillation rate of the alkanol (R'OH) generated as the reaction progresses, but is about 2 to 20 hours when the alkanol is methanol. This reaction is preferably carried out in the presence of a catalyst. Catalysts that can be used are generally those effective for forming an ester from a carboxylic acid and an alkanol, but particularly preferred are those consisting of an organic acid typified by para-toluenesulfonic acid.
For example, in the case of para-toluenesulfonic acid, the amount of catalyst used is about 100 ppm to 1% by weight based on the total amount of compound (A) and acrylic compound.
Preferably, it is usually about 1000 to 5000 ppm. Since acrylic compounds are present as reactants and in the products in this reaction system, it is generally necessary to prevent their polymerization.
Various compounds are known for preventing the polymerization of ethylenically unsaturated bonds, and any suitable compound can be used in this reaction as well. Specific examples include phenolic compounds, amine compounds, and air. Blowing air into the reaction system is preferable because air can not only inhibit polymerization but also promote the distillation of the alkanol (R'OH) produced. Note that since air alone may not have sufficient polymerization inhibitory effect, it is preferable to use a polymerization inhibitor other than air in combination. This reaction can be carried out according to various convenient operating modes. in particular,
For example, compound (A), an acrylic compound, and a catalyst (and optionally a solvent or dispersion medium) are placed in a reactor equipped with a stirrer, a cooler, and an air blower, and a small amount of air is added to the reaction system (liquid phase). part) while gradually increasing the temperature.
Distillation of alkanol (R'OH) begins when the reaction system temperature reaches around 100°C, and the reaction is completed by raising the temperature to around 125 to 150°C and continuing heating until the distillation of alkanol stops. (4) Product The thermosetting resin of formula () thus produced is generally a pale yellow transparent viscous liquid. Some compounds of formula () can be isolated and purified by conventional methods such as recrystallization. Since this compound has at least one ethylenically unsaturated bond derived from an acrylic compound, it is polymerized and cured by radical polymerization (or ionic polymerization in some cases). When the bound acrylic compound is 1 mole, the cured product obtained by polymerization will usually be soluble, but when the bound acrylic acid is 2 moles or more, the cured product will be soluble. It is usually insoluble and infusible. 2 Thermosetting resin composition The composition according to the present invention is a polymerization initiator capable of radical polymerization (or ionic polymerization) of a melamine group-containing (meth)acrylate represented by the formula () and this (meth)acrylate moiety. This includes the following: In a preferred embodiment of the invention, the composition, in addition to the two essential components mentioned above, also contains an ethylenically unsaturated compound copolymerizable with the (meth)acrylate moiety. In this aspect,
The composition of the present invention is structurally similar to so-called unsaturated polyester resins. Therefore, techniques customary for unsaturated polyester resins can be utilized within reasonable limits. (1) Thermosetting resin component This component is a melamine group-containing (meth)acrylate represented by the formula (). In addition, when referring to "thermosetting resin" in the present invention, as is clear from the fact that unsaturated polyester resin is classified as a thermosetting resin and its curing is not limited to heating, shall mean a resin that can be cured by various curing means. (2) Polymerization initiator component The polymerization initiator used varies depending on the curing mode to be adopted. For example, in the case of ultraviolet curing, examples include benzophenone, benzoin ethers, anthraquinones, etc., and in the case of heat curing, examples include azo compounds, organic peroxides, etc. Some specific examples of these polymerization initiators are as follows. Benzoyl peroxide, methyl ethyl ketone peroxide, acetyl peroxide,
t-butyl hydroperoxide, di-t-
Butyl peroxide, cumene hydroperoxide, dicumyl peroxide, t-butyl perbenzoate, parachlorobenzoyl peroxide, cyclohexanone peroxide, t-butyl acetate, etc. The amount of the polymerization initiator used is usually about 0.01 to 5% by weight based on the (meth)acrylate of formula (). In addition, when an ethylenically unsaturated monomer is used in combination according to a preferred embodiment, it goes without saying that the amount of polymerization initiator for the polymerization should be considered. (3) Ethylenically unsaturated monomer The ethylenically unsaturated monomer used in the preferred embodiment of the composition of the present invention is any monomer that can be copolymerized with the (meth)acrylate moiety of the compound of formula (). It's possible. Particularly preferred monomers are those capable of dissolving the two essential components and optionally used auxiliary components to form a homogeneous solution. Specific examples of such monomers include styrene, vinyltoluene, chlorostyrene,
Vinyl styrene, methyl methacrylate, acrylic acid, 2-hydroxyethyl acrylate, tetrahydrofuryl methacrylate, 2
- ethylhexyl methacrylate, trimethylolpropane triacrylate, diallyl phthalate, and mixtures thereof. The amount of such monomer used is arbitrary, but to give an example, the amount of the compound of formula ()
The amount is about 250% by weight, preferably 60-140% by weight. (4) Other components In addition to the above-mentioned components, the composition of the present invention may contain any appropriate auxiliary components. Specific examples of such auxiliary ingredients include:
Solvents such as acetone, methyl ethyl ketone, dimethylformamide, ethyl acetate, etc., thermal polymerization inhibitors such as hydroquinone, ultraviolet absorbers such as 2,4-dihydroxybenzophenone, 2-hydroxy-4
-Methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, "Tinuvin P" (manufactured by Ciba), other antioxidants,
There may be colorants, fillers or reinforcing agents such as glass fibers or woven fabrics thereof, clays, carbon fibers, and the like. (5) Applications The composition of the present invention can be formed into various molded products by, for example, films, sheets, boards, cast molding, injection molding, transfer molding, etc. The product has high hardness and excellent heat resistance and electrical properties, so it can be used in a wide range of industrial fields. 3 Experimental example Reference example In a 2-liter separable flask equipped with a stirrer, a distillation cooler, and a glass tube for blowing air,
Hexamethoxymethylmelamine (manufactured by Mitsui Toatsu Co., Ltd.)
Product name "Cymel #303") 780 parts, methacrylic acid
516 parts of paratoluenesulfonic acid, 3.5 parts of para-toluene sulfonic acid, and 1.5 parts of hydroquinone methyl ether were charged, and the mixture was gradually heated while blowing air. Methanol began to distill off when the temperature in the reaction system reached around 100°C. Subsequently, the reaction was continued by heating to 120-130℃, and when the distillation of methanol stopped, the temperature of the reaction system was cooled to about 70℃, and the remaining methanol was completely removed under reduced pressure, resulting in a pale yellow viscous A thick product was obtained. Example 1 To 100 parts of the resin obtained in Reference Example, 30 parts and 40 parts of styrene monomer were added, and methyl ethyl ketone peroxide (manufactured by NOF Corporation,
1.0 part of the product (trade name: "Permec") and 0.5 part of cobalt naphthenate were mixed. Pour this mixture into two 300x
The mixture was poured into a mold with a gap of 3 mm and made of 300 mm glass plates, and cured at room temperature for 24 hours, then at 80°C for 2 hours, and at 120°C for 1 hour. The physical properties of the obtained cured product were as follows.

【table】

[Table] Example 2 A composition having the formulation shown in Table 1 was prepared using the resin obtained in the reference example, and this was pressure molded at 120 to 130°C for 5 minutes. Its physical property values are shown in Table 2.

【table】

[Table] Example 3 In a 2-liter flask equipped with a stirrer, a distillation cooler, and a glass tube for blowing air, tetramethoxymethylbenzoguanamine (manufactured by Mitsui Toatsu Co., Ltd., product name: Cymel #11~ 3) 766 parts, methacrylic acid
689 parts of p-toluenesulfonic acid, and 1.4 parts of hydroquinone methyl ether were added, and the mixture was reacted at 120 to 130°C while blowing air. When there was no more distillate, the reaction system was cooled to about -70°C, and residual methanol was completely removed under reduced pressure to obtain a pale yellow viscous substance. 100 parts of the resin thus obtained were mixed with 30 parts of styrene monomer, 0.5 part of cobalt naphthenate, and 1 part of methyl ethyl ketone peroxide.
Pour between two glass plates and at room temperature for 24 hours at 80°C.
It was cured at 120° C. for 2 hours and then at 120° C. for 1 hour. The physical properties of the obtained cured product were as follows. Bending strength (Kg/mm ² ) 10.2 Bending modulus (Kg/mm ² ) 350 Barcol hardness 60 Heat distortion temperature (℃) 154

Claims (1)

[Scope of Claims] 1. A thermosetting resin composition comprising a melamine group-containing (meth)acrylate represented by the following formula () and a polymerization initiator. In the formula, R is a methyl group, a phenyl group,
[Formula] or an organic group represented by the following formula. Y each represents hydrogen or Z ¹¹ . Z ¹ to Z ¹¹ are each - CH ₂ OCOCR ¹ = CH ₂ or - CH ₂ OR ²
shows. At least one of the existing Z ¹ to Z ¹¹ is -CH ₂ OCOR ¹ =CH ₂ . R ¹ each represents hydrogen or a methyl group, and R ² represents an alkyl group having 1 to 4 carbon atoms.