JP2001164131A - Flame-retarded resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame-retarded resin composition which is excellent in flame retardance though it does not contain a halogen and a phosphorus compound. SOLUTION: This composition comprises a resin, especially a phenol resin or a modified phenol resin, and a layered double hydroxide dispersed therein in a peeled state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant resin composition containing no halogen and phosphorus compounds and having excellent flame retardancy.

[0002]

2. Description of the Related Art Flame-retardant materials containing no halogen have been actively developed in response to environmental problems. For example, various methods have been proposed, such as highly filling a metal hydroxide as a flame retardant, or using a phosphorus-based flame retardant in combination with a nitrogen-based flame retardant. However, when the metal hydroxide is filled at a high level, the workability decreases, and when a thin molded product is used,
Problems such as not exhibiting sufficient flame retardancy occur. Further, a phosphorus-based flame retardant cannot be said to be a flame retardant that is completely environmentally friendly, for example, due to regulations on drainage, and furthermore, there is a danger of explosion during production.

In order to solve these problems, a method of finely dispersing a filler has been considered. For example, a method of dispersing montmorillonite in a polyamide resin in a peeled state (JP-A-63-230766, JP-A-6-230766)
No. 4-1157) has been proposed, and it is known that these techniques can improve mechanical properties and some flame retardancy. However, since the resin is a polyamide or the filler is a layered silicate that does not itself exhibit flame retardancy, it has not yet achieved a sufficient effect as a flame retardant resin.

It is considered that metal hydroxides are finely dispersed, but it is difficult to make metal hydroxides into fine powder, and the average particle size is limited to the submicron order. Even if fine powder of metal hydroxide is formed, aggregation is likely to occur due to the influence of surface hydroxyl groups, and it has been difficult to disperse the powder with a primary particle size.

Further, a flame retardant (US Pat. No. 4,883,533, U.S. Pat.
Although S5225115) has been proposed, a flame retardant containing halogen or phosphorus should not be used in consideration of environmental impact as described above. From the above, the development of a flame retardant containing no halogen or phosphorus has been desired.

The layered double hydroxide used in the present invention is a compound whose layer is positively charged and which contains a negative ion such as a carbonate ion between the layers. Unlike a compound which is negatively charged and contains a positive ion such as sodium ion between layers, a conventional method (Japanese Patent Laid-Open No.
In JP-A-3-230766 and JP-A-64-11157, it is impossible to enlarge the interlayer.

Further, the layered double hydroxide has an interlayer distance (base distance) of about half that of a layered silicate such as montmorillonite, and has a large number of hydroxyl groups on the surface of the layer. Since they are linked by hydrogen bonds, it is difficult to finely disperse them in a state in which they are separated in a resin, and such a technique has not yet been established.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flame-retardant resin composition containing no halogen and phosphorus compounds and having excellent flame retardancy.

[0009]

Means for Solving the Problems The inventors of the present invention have studied the separation and dispersion of a layered double hydroxide, and as a result, have found that a layered double hydroxide is dispersed in a resin in a state of being separated. By dispersing the layered double hydroxide in a denatured phenol resin in a peeled state, it has been found that the composition exhibits high flame retardancy without containing phosphorus or halogen, and the present invention has been completed. That is, the first invention of the present invention is a flame-retardant resin composition characterized in that a layered double hydroxide is dispersed in a resin in a state of being separated. The second invention is a step of synthesizing a phenolic resin or a modified phenolic resin, mixing a compound having a phenolic hydroxyl group and a layered double hydroxide, and removing the layered double hydroxide in the phenolic resin or the modified phenolic resin. It is a flame-retardant phenol resin composition characterized by being dispersed. Further, in the third invention, a compound having a phenolic hydroxyl group and a layered double hydroxide are mixed in the step of synthesizing the phenolic resin or the modified phenolic resin, and the layered double hydroxide is separated from the phenolic resin or the modified phenolic resin. Disperse in
A flame-retardant epoxy resin composition characterized by further being glycidyl etherified.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The layered double hydroxide used in the present invention refers to a layered structure formed by stacking a number of layers via a positively charged base layer and a negatively charged intermediate layer of a metal hydroxide. And represented by the general formula (1). Here, each symbol in the formula represents the following contents. M ²⁺ : Mg ²⁺ , Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu
^2+, divalent metal M ³⁺ such ^{Zn 2+: Al 3+, Fe 3+} , Cr 3+, Co 3+, 3 -valent metals such as ^{In 3+ A n-: OH -,} F -, Cl _{^{-, NO 3 -, SO 4}} 2-, C
N-valent anions such as O ₃ ²⁻ , CH ₃ COO ⁻ , oxalate ion, maleate ion, adipate ion, phthalate ion, salicylate ion, etc. x: 0.1 ≦ x <0.4 n: A (anion) negative Ionic valence y: Real number greater than 0

More preferably, it is represented by the general formula (2). Here, each symbol in the formula represents the following contents. M ²⁺ : Mg ²⁺ or Zn ²⁺ x: 0.2 ≦ x <0.4 y: real number larger than 0

More preferably, hydrotalcite represented by the general formula (3) is used. x: 0.2 ≦ x <0.4 y: real number greater than 0

(C) represented by the general formulas (2) and (3)
To produce a layered double hydroxide of the O ₃ ) type, for example, M
An aqueous solution of Na ₂ CO ₃ corresponding to half the number of moles of Al was added to a mixture of MgCl ₂ (or ZnCl ₂ ) aqueous solution and AlCl ₃ aqueous solution (Mg (or Zn): Al = 2 to 4: 1, molar ratio). In some cases, the pH of the solution is adjusted to about 9 to 10 with an aqueous HCl solution or an aqueous NaOH solution, kept at about 20 to 90 ° C., reacted and aged, and the precipitated product is separated and washed, and then washed at 40 to 70 ° C. Obtained by drying.

Further, in order to produce the layered double hydroxide represented by the general formula (1), other divalent and trivalent metal salts other than Mg (or Zn) or Al salts are used as raw materials. ,
It is made by a method similar to the above, except that decarbonated water is used to produce LDH that is not in the (CO ₃ ) form, or that the reaction is carried out under a nitrogen atmosphere, so that carbonate ions do not enter during the reaction. is necessary.

The average particle size of the layered double hydroxide is from 1 nm to 20 nm.
μm is preferred, more preferably 1 nm to 1 μm, and most preferably 1 nm to 0.5 μm. If the average particle size exceeds 20 μm, the particles cannot be sufficiently dispersed in the resin, and a sufficient flame retardant effect may not be exhibited. 1 nm
If it is smaller than this, the basicity becomes strong, which may cause deterioration of the resin or inhibition of curing in a thermosetting resin. When the average particle size exceeds 20 μm, there is a problem in workability. However, the average particle size in the above range may be used. These average particle diameters can be measured by static light scattering, dynamic light scattering, observation with an electron microscope, or the like.

These layered double hydroxides may be used without surface treatment or may be used after surface treatment. Also,
An organic compound in which an organic compound is intercalated between layers in advance can be used.

Examples of the organic compound which can be surface-treated or intercalated between layers include aliphatic polyhydric alcohols such as glycerol and glycol, phenol, resorcinol, cresol such as o-cresol, m-cresol, p-cresol, and p-cresol. Bis-phenols such as para-alkylphenols such as -tert-octylphenol, p-nonylphenol and p-tert-butylphenol, cashew oil containing p-phenylphenol, cardol, cardanol and anacardic acid as main components, bisphenol A, bisphenol F and bisphenol AD And organic acids such as methylolphenol, stearic acid, oleic acid, oxalic acid, maleic acid, adipic acid, phthalic acid and lauric acid, acid anhydrides of organic acids, and organic acid salts. It may be used alone or Kutomo. Among them, the number average molecular weight is preferably 300 or less, more preferably 250 or less, and most preferably 15 or less, from the viewpoint of ease of intercalation.
0 or less.

As the method of intercalation, a method in which the layered double hydroxide and the above-mentioned organic compound are melt-mixed while heating, if necessary, an optional method in an organic solvent such as alcohol (methanol, ethanol, etc.) or distilled water. The layered double hydroxide is calcined at about 500 ° C. for about 2 hours and then rehydrated in an aqueous solution containing an organic compound to incorporate the organic compound between the layers. Rehydration method, vacuum heating method in which organic compounds are heated and evaporated under reduced pressure to incorporate organic compounds between layers, crystal method in which organic compounds and layered double hydroxide are crystallized, and organic methods in which organic compounds are incorporated between layers by grinding Supercritical method of intercalating organic matter between layers in the supercritical state of carbon dioxide,
And a combination thereof.

Cresols such as phenol, resorcin, o-cresol, m-cresol and p-cresol;
When intercalating organic compounds such as oxalic acid, maleic acid, adipic acid, phthalic acid, lauric acid, and organic compounds having relatively low molecular weight such as acid anhydrides and organic acid salts of organic acids, it is relatively simple. It is relatively easy to mix by heating at a desired temperature in an organic solvent such as alcohol (methanol, ethanol, etc.) or distilled water at a desired temperature. Organic compounds can be intercalated.

As the layered double hydroxide, commercially available products (for example, Kyoward 500, Kyoward 1000, D
HT-4A (Kyowa Chemical Industry Co., Ltd.) may be used.

The resin used in the present invention is a thermoplastic resin, a thermosetting resin, or a mixture thereof. The thermoplastic resin is polyethylene, polypropylene, polybutene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butyl acrylate copolymer (EBA), ethylene-
Methyl methacrylate copolymer (EMMA), poly-4
-Methyl-1-pentene, α-olefin copolymer and the like,
And a polyolefin, a polyamide, an acrylic resin, a styrene resin, a polycarbonate resin, a polyphenylene oxide, a polyether sulfone, a polysulfone, a polyphenylene sulfide, a polyarylate resin, and the like, which are composed of a mixture thereof. Considering the flame retardancy, ethylene-vinyl acetate copolymer (EVA), polyphenylene sulfide, and polyarylate resin are preferred.

The thermosetting resin includes an epoxy resin, a phenol resin, a modified phenol resin, a melamine resin and the like. It is preferable to use a thermosetting resin to disperse the layered double hydroxide in a peeled state, more preferably a phenol resin, a modified phenol resin, an epoxy resin, and most preferably a phenol resin having good flame retardancy, Modified phenolic resins or mixtures thereof. The phenol resin may be a novolak type resin or a resol type resin.

Further, the modified phenolic resin refers to a resin having a phenolic hydroxyl group other than the phenolic resin,
For example, resorcinol resin, resorcinol-modified phenolic resin, cresol resin, cresol-modified phenolic resin,
Paraalkylphenol / formaldehyde resin, non-thermally reactive alkylphenol resin, thermally reactive alkylphenol resin, cashew-modified phenolic resin, aromatic hydrocarbon resin-modified phenolic resin, melamine-modified phenolic resin, oil-modified phenolic resin, terpene-modified phenolic resin, furan-modified Phenolic resins, benzoxazine resins, calixarenes, bisphenols such as bisphenol A, bisphenol F, bisphenol AD,
Bisphenol sulfone, cumylphenol, epoxy-modified phenolic resin, aniline-modified phenolic resin, phenoxy resin-modified phenolic resin, urea-modified phenolic resin, lignin-modified phenolic resin, rubber-modified phenolic resin, sulfur-modified phenolic resin, and the like. One or more can be used.

Examples of the epoxy resin include a glycidyl ether-based epoxy resin obtained by glycidyl etherification by the reaction of a phenol resin or a modified phenol resin with epichlorohydrin, and a cycloaliphatic epoxy obtained by oxidizing a double bond of a cyclohexene ring to epoxidize it. Resins, glycidyl ester-based epoxy resins obtained by the reaction of carboxylic acid and epichlorohydrin, glycidylamine-based epoxy resins obtained by glycidylation of amines, crystalline triglycidyl isocyanate having a triazine ring, and hydantoin-type epoxy resins obtained by glycidylation of a hydantoin ring. And at least one of them can be used.

Among them, phenol novolak type epoxy resins and cresol novolak type epoxy resins belonging to glycidyl ester type epoxy resins having excellent heat resistance, chemical resistance and water resistance are preferred for use in semiconductor encapsulants.

The compound having a phenolic hydroxyl group used in the present invention includes phenol, resorcinol, o-
Main ingredients are cresols such as cresol, m-cresol and p-cresol, para-alkylphenols such as p-tert-octylphenol, p-nonylphenol and p-tert-butylphenol, p-phenylphenol, cardol, cardanol and anacardic acid. Examples include cashew oil, bisphenols such as bisphenol A, bisphenol F and bisphenol AD, and methylol phenol. Among them, the number average molecular weight is preferably 300 or less, more preferably 250 or less, and most preferably 150 or less from the viewpoint of easy intercalation.

The term "dispersed in a peeled state" as used in the present invention means that one layered double hydroxide layer or a layered state of several layers or less within a range that does not reduce the flame retardancy of the material. Are dispersed with a sufficient interlayer distance (in a so-called infinite swelling state). After the layered double hydroxide is dispersed in the resin, powder X-ray diffraction measurement is performed, and the 003 plane spacing in the spectrum is measured. (spacing of 003 surface d ₀₀₃₎ basal plane spacing value obtained from the peak maximum caused by d ₀₀₃ is 2
0 ° or more, preferably 30 ° or more, more preferably 3 °
5 ° or more, most preferably 45 ° or more. Bottom interval value here (surface interval d _{003 of 003} )
Is 45 ° or more in a measurement angle range of 2 ° or more and 003
This indicates a state in which a peak due to the plane spacing _d003 is not clearly present in the powder X-ray diffraction spectrum.

As a method of dispersing the layered double hydroxide in a resin in a peeled state, a method of separating and dispersing the layered double hydroxide in the resin synthesizing step is to intercalate the monomer constituting the resin into the layered double hydroxide and simultaneously form the resin. It is preferable to promote the synthesis of the compound, and to polymerize the intercalated monomer between the layers of the layered double hydroxide to increase the molecular weight, thereby enlarging the layers and separating and dispersing them.

In particular, in the step of synthesizing a phenolic resin or a modified phenolic resin, a layered double hydroxide is introduced, and the layer of the layered double hydroxide is expanded together with the synthesis of the phenolic resin or the modified phenolic resin. Can be dispersed in a phenolic resin or a modified phenolic resin in a peeled state. Further, by glycidyl etherification of the phenol resin composition or modified phenol resin composition dispersed in a state where the layered double hydroxide is peeled off, the layered double hydroxide is peeled into the glycidyl ether-based epoxy resin. A dispersed resin composition can be obtained.

For example, a compound having a phenolic hydroxyl group and a layered double hydroxide are mixed for a predetermined time at a predetermined temperature and, if necessary, while heating, a carbonyl compound such as acetone, formaldehyde, acetaldehyde, paraformaldehyde or the like is added thereto. Add para-xylene dimethyl ether and, if necessary, organic acids or anhydrides such as acetic acid, oxalic acid, and maleic acid; sulfonic acids such as paratoluenesulfonic acid; and inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid. Acidic catalyst, or in the presence of a basic catalyst such as calcium hydroxide, potassium hydroxide, sodium hydroxide, ammonia, etc., by reacting for a predetermined time and dehydrating if necessary, in a state where the layered double hydroxide has been peeled off. A dispersed phenolic resin composition or a modified phenolic resin composition can be obtained.

Further, by adding epichlorohydrin to the mixture and subjecting it to glycidyl etherification in the presence of an alkali catalyst, it is possible to obtain a resin composition in which the layered double hydroxide is dispersed in a glycidyl ether-based epoxy resin in a peeled state. .

In the step of synthesizing the phenolic resin composition or the modified phenolic resin composition, alkylbenzene such as toluene, xylene and mesitylene, drying oil such as melamine, tung oil and linseed oil, terpenes, furfural, furfuryl alcohol, aniline, Modifiers such as urea, lignin, rubber and sulfur may be added.

The content of the layered double hydroxide in the resin is 0.1
To 70% by weight, more preferably 0.5 to 3% by weight.
0% by weight, most preferably 1 to 10% by weight. When the content of the layered double hydroxide in the resin is less than 0.1% by weight, sufficient flame retardancy cannot be exhibited, and when it exceeds 70% by weight, the layered double hydroxide can be sufficiently peeled off. In addition, not only the desired flame retardancy cannot be exhibited, but also the viscosity of the resin composition increases, and molding may not be performed.

The flame-retardant resin composition of the present invention may be used as it is as a flame-retardant resin composition, or may be added as a flame retardant to other various resin compositions. As other resin compositions, a resin composition containing a thermosetting resin or a thermoplastic resin as a main component, a metal hydroxide such as magnesium hydroxide or aluminum hydroxide, a metal carbonate such as calcium carbonate,
Metal fillers such as silica, alumina, copper oxide, iron oxide, and zinc oxide, and various fillers such as talc, wollastonite, glass fiber, and carbon black may be contained.
When mixed with another resin composition, mixing roll, Banbury mixer, pressure kneader, twin-screw kneader,
An ordinary kneader such as a KCK kneader can be used.

The flame-retardant resin composition of the present invention, or another resin composition to which it is added as a flame retardant, may have other surface treatments, if necessary, as long as the effects of the present invention are not impaired. Agents, copper damage inhibitors, crosslinking agents, reinforcing agents, coloring agents, antioxidants, ultraviolet absorbers, processing aids, lubricants, stabilizers and other additives.

The mechanism by which the high flame retardancy of the present invention has been developed is not clear. However, since the layered double hydroxide is homogeneously dispersed, strong combustion generated from a large resin mass is eliminated. It is considered that the effect of homogenizing the amount of water generated from the layered double hydroxide, and the shielding effect of the layered double hydroxide, etc., could be combined to achieve high flame retardancy.

[0037]

The present invention will be described in more detail with reference to the following examples. <Example 1> Phenol and DHT- manufactured by Kyowa Chemical Co., Ltd.
4A (average particle size: 0.47 μm) was mixed at a weight ratio of 9: 1, and the mixture was stirred and mixed at 60 ° C. for about 5 hours, sampled, and the powder was subjected to X-ray diffraction measurement. (spacing of 003 surface d ₀₀₃₎ basal plane spacing value obtained from the peak maximum caused by lattice spacing d ₀₀₃ 7.
It was 6Å. Next, paraformaldehyde was mixed with the mixture of phenol and DHT-4A so that the molar ratio of phenol to paraformaldehyde was 1: 0.6, and 1: 1.
The temperature was raised to 30 ° C., and the reaction was allowed to proceed for about 10 hours.
Thereafter, dehydration under normal pressure and vacuum was carried out while the temperature was further increased to obtain a phenol resin composition (a) dispersed in a state where the layered double hydroxide was separated from the phenol resin.

[0038] In the phenol resin composition was sampled from (a), the powder X-ray diffraction measurements were carried out, the peak value from 2 to 40 ° measurement range due to the lattice spacing d ₀₀₃ of 003 faces in the spectrum No observation was made, and it was confirmed that the bottom surface interval value (surface interval d _{003 of the} 003 surface) was 45 ° or more. In addition, it was confirmed that the phenol resin composition (a) had transparency. Further, the content of the layered double hydroxide (peeled off state) in the phenol resin composition (a) was 11.92 wt%. The various materials shown in Table 1 were mixed at about 100 ° C. using a mixing roll, and the flame retardancy of this resin composition was evaluated. Table 1 shows the results of the flame retardancy evaluation.

<Example 2> Epichlorohydrin was added to the phenolic resin composition (a) obtained in Example 1 so that the phenolic hydroxyl group and chlorine equivalent became equal, and the reaction was allowed to proceed under an alkaline catalyst. Thereby, the epoxy resin composition (b) dispersed in a state where the layered double hydroxide is peeled off
I got As a result of sampling from this epoxy resin composition (b) and performing powder X-ray diffraction measurement, the peak value attributable to the _d003 of the 003 face in the spectrum was 2
It was not observed in the measurement range of ゜ 40 °, and the bottom surface interval value (003
It was confirmed that the surface distance d ₀₀₃ ) was 45 ° or more. In addition, it was confirmed that the epoxy resin composition (b) had transparency. Further, the content of the layered double hydroxide (peeled state) in the epoxy resin composition (b) is 1
2.03 wt%. The various materials shown in Table 1 were mixed at about 100 ° C. using a mixing roll, and the flame retardancy of this resin composition was evaluated. Table 1 shows the results of the flame retardancy evaluation.

Example 3 Phenol and Kyowa Chemical Co., Ltd.
A mixture obtained by mixing DHT-4A (average particle size: 0.47 μm) at a weight ratio of 7: 3 was stirred and mixed at 60 ° C. for about 5 hours, sampled, and the powder was subjected to X-ray diffraction measurement. Bottom spacing value obtained from the peak maximum value resulting from the ₀₀₃ face spacing d ₀₀₃ (the 003 face spacing d
₀₀₃ ) was 7.6Å. Next, phenol and DH
Paraformaldehyde was mixed with the mixture of T-4A so that the molar ratio of phenol to paraformaldehyde was 1: 0.6, and the temperature was increased to 130 ° C. to allow the reaction to proceed for about 12 hours. Thereafter, the mixture was subjected to normal pressure dehydration and vacuum dehydration while further raising the temperature to obtain a phenol resin composition (c) dispersed in the phenol resin in a state where the layered double hydroxide was peeled off.

[0041] In the phenol resin composition was sampled from (c), powder X-ray diffraction measurements were carried out, the peak value from 2 to 40 ° measurement range due to the lattice spacing d ₀₀₃ of 003 faces in the spectrum No observation was made, and it was confirmed that the bottom surface interval value (surface interval d _{003 of the} 003 surface) was 45 ° or more. In addition, it was confirmed that the phenol resin composition (c) had transparency. Further, the content of the layered double hydroxide (peeled off state) in the phenol resin composition (c) was 35.89% by weight. The various materials shown in Table 1 were mixed at about 100 ° C. using a mixing roll, and the flame retardancy of this resin composition was evaluated. Table 1 shows the results of the flame retardancy evaluation.

<Comparative Examples 1 and 3> In the same manner as in Example 1, phenol resin (d) was prepared without adding DHT-4A. Various materials shown in Table 1 were mixed at about 100 ° C. using a mixing roll, and the flame retardancy of this resin composition was evaluated. Table 1 shows the results of the flame retardancy evaluation. <Comparative Example 2> Phenol resin (d) produced in Comparative Example 1
And the epoxy resin (e) in the same manner as in Example 2.
Was prepared. Various materials shown in Table 1 were mixed at about 100 ° C. using a mixing roll, and the flame retardancy of this resin composition was evaluated. Table 1 shows the results of the flame retardancy evaluation.

<Various Evaluations> (1) Bottom distance (d ₀₀₃ ): Measured using an X-ray diffractometer RASA-5R manufactured by Rigaku Corporation. (2) Average particle size: measured by adding a layered double hydroxide to an alcohol solvent and using a laser diffraction / scattering type particle size distribution analyzer LA-910 of Horiba, Ltd. (3) Flame retardancy: A pressed sheet having a thickness of 1 mm was prepared by pressing at 175 ° C. for 10 minutes, and a vertical flame retardancy test was performed according to UL94.

[0044]

[Table 1]

[0045]

According to the present invention, it is possible to provide a flame-retardant resin composition containing no halogen and phosphorus compounds and having excellent flame retardancy.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) C08L 63/00 C08L 101/00 F term (reference) 4J002 AA001 AA011 AA021 BB001 BB031 BB061 BB071 BB121 BB171 BC021 BG001 CC031 CC041 CC051 CC061 CC071 CC181 CD001 CF161 CG001 CH001 CL001 CN021 CN031 DE046 DE076 DE146 DE186 EJ017 EJ027 EJ037 FD010 FD130 FD136

Claims (6)

[Claims] 1. A flame-retardant resin composition characterized in that a layered double hydroxide is dispersed in a resin in a state of being separated. 2. The flame-retardant resin composition according to claim 1, wherein the resin is at least one member selected from the group consisting of a phenol resin, a modified phenol resin and an epoxy resin. 3. A compound having a phenolic hydroxyl group and a layered double hydroxide are mixed in a step of synthesizing a phenolic resin or a modified phenolic resin, and the layered double hydroxide is separated into the phenolic resin or the modified phenolic resin. A flame-retardant phenolic resin composition characterized by being dispersed. 4. In a step of synthesizing a phenolic resin or a modified phenolic resin, a compound having a phenolic hydroxyl group is mixed with a layered double hydroxide, and the layered double hydroxide is separated into the phenolic resin or the modified phenolic resin. A flame-retardant epoxy resin composition characterized by being dispersed and further glycidyl etherified. 5. The flame-retardant resin composition according to claim 1, wherein the layered double hydroxide is hydrotalcite. 6. The flame-retardant resin composition according to claim 1, wherein the average particle diameter of the layered double hydroxide is 1 μm or less.