JPH08337683A - Flame-retardant thermosetting resin composition - Google Patents

Abstract

PURPOSE: To obtain a flame-retardant thermosetting resin composition which is excellent in punchability at a low temperature, tracking resistance, heat resistance and insulating properties and gives a laminate excellent in resistance to bleeding of a flame retardant by blending a thermosetting resin with a specified aromatic phosphate. CONSTITUTION: This composition is formed by blending a thermosetting resin (e.g. phenolic resin) with an aromatic phosphate represented by the formula (wherein R<1> and R<2> are each a lower alkyl, preferably the same lower alkyl; R<3> is H or a lower alkyl; R<4> is a 6-20C aromatic hydrocarbon residue; and n is 2 or 3) [e.g. tris(2,6-dimethylphenyl) phosphate], preferably at a weight ratio of 100:(0.1 to 100).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a flame-retardant thermosetting resin composition, and more particularly to a flame-retardant thermosetting resin composition containing an aromatic phosphate.

[0002]

2. Description of the Related Art Thermosetting resins typified by polyurethane and phenolic resins have excellent properties such as relatively low cost and easy molding, so that
It is widely used in electronic parts and automobile parts. However, these resins are flammable and have a property of causing uncontrollable combustion with one ignition, and various efforts have been made in this industry to make them flame-retardant. Further, today, in some of the fields of use of these resins, flame retardation is obligatory.

In order to impart flame retardancy to the thermosetting resin, a method of adding a flame retardant at the time of preparing a resin molded product is adopted. Examples of the flame retardant added include inorganic compounds, organic phosphorus compounds, organic halogen compounds and halogen-containing organic phosphorus compounds. Although the organic halogen compound and the halogen-containing organic phosphorus compound exhibit an excellent flame retardant effect, there is a problem in that hydrogen halide gas is generated by thermal decomposition.

The halogen-free flame retardants include inorganic compounds and organic phosphorus compounds. Inorganic compounds typified by magnesium hydroxide and aluminum hydroxide have a significantly low flame retardant effect and need to be added in large amounts, which impairs the original physical properties of the resin (for example, processability and mechanical properties). There's a problem. Organophosphorus compounds represented by triphenyl phosphate (TPP), tricresyl phosphate (TCP), cresyl diphenyl phosphate (CDP), etc. are widely used because of their relatively good flame retardant effect. The high heat resistance of the resin,
There is a problem that mechanical properties are deteriorated. JP-A 1-2
No. 42633 and No. 2-67310 disclose a phenol resin containing an aromatic phosphate. These are excellent in low temperature punching workability, but the electrical and mechanical properties of the molded product are deteriorated.

The thermosetting resin is widely used as an insulating substrate for electronic circuit wiring in the form of a laminated plate, and is particularly required to have insulating properties and heat resistance. For example, a laminated board using a phenol resin has a solder heat resistance of 15 to 40 seconds and an insulation resistance of 1 × 10 ¹⁰ to 1 × 10 ¹³ . However, when an auxiliary material is added for the purpose of improving physical properties such as flame retardancy, the desired physical properties are improved, but the main physical properties may be deteriorated due to volatilization of the additives. Under such circumstances, in the flame retardant for thermosetting resin, a flame retardant that has low volatility and does not deteriorate the physical properties of the resin has been desired.

[0006]

DISCLOSURE OF THE INVENTION In order to solve the above-mentioned drawbacks of the prior art, the present invention is a flame-retardant thermosetting composition comprising a flame-retardant agent which has low volatility and does not deteriorate the physical properties of the resin. An object is to provide a resin composition. Specifically, it is a flame-retardant heat compounded with an aromatic phosphate that has low volatility and improves the electrical resistance and mechanical properties without lowering the heat distortion temperature and imparts excellent flame retardancy. It is intended to provide a curable resin composition.

[0007]

Means for Solving the Problems In view of the above-mentioned problems, the present inventors have earnestly studied and obtained the following findings. The aromatic phosphate represented by the general formula (I) not only has an excellent effect as a flame retardant, but is also excellent in heat resistance by adding the above compound as a flame retardant to a thermosetting resin, and is excellent in resin. It has been found that the electrical resistance and mechanical properties of can be significantly improved.

It is considered that the above-mentioned characteristic improvement results from the steric hindrance of the aromatic phosphate. That is, the aromatic phosphate represented by the formula (I) is characterized by having a substituent at the 2,6 position of the benzene ring. It is also considered that this steric hindrance improves the hydrolysis resistance over a long period of time. That is, according to the present invention,
(A) Thermosetting resin, (b) General formula (I):

[0009]

Embedded image

(Wherein R ¹ and R ² are the same or different lower alkyl groups, R ³ is a hydrogen atom or a lower alkyl group, R ⁴ is an aromatic hydrocarbon residue having 6 to 20 carbon atoms, and n is 2 or An integer of 3) is provided to provide a flame-retardant thermosetting resin composition, characterized by comprising an aromatic phosphate.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The flame-retardant thermosetting resin composition of the present invention comprises (a) a thermosetting resin and (b) an aromatic phosphate.

The thermosetting resin used as the component (a) of the resin composition of the present invention includes acrylic resin, polyurethane resin, phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin and diallyl phthalate resin. Etc. Two or more kinds of the above resins may be mixed and used. The aromatic phosphate used as the component (b) is represented by the general formula (I).

Examples of the lower alkyl group for R ¹ , R ² and R ³ in the general formula (I) include straight chain or branched alkyl groups having 1 to 4 carbon atoms. Examples thereof include a methyl, ethyl, propyl, isopropyl, butyl or isobutyl group. Examples of the aromatic hydrocarbon residue having 6 to 20 carbon atoms for R ⁴ include a phenyl or naphthyl group substituted with a lower alkyl group having 1 to 4 carbon atoms (for example, a methyl or ethyl group). Examples thereof include phenyl, tolyl, xylyl, mesityl, cumenyl, naphthyl, methylnaphthyl, dimethylnaphthyl, ethylnaphthyl and the like.

Preferred specific examples of the aromatic phosphate represented by the general formula (I) include tris (2,6-dimethylphenyl) phosphate, tris (2,4,6-trimethylphenyl) phosphate and bis (2,6-dimethyl). Phenyl) phenyl phosphate, bis (2,4,6-trimethylphenyl) phenyl phosphate, bis (2,6-)
Dimethylphenyl) cresyl phosphate, bis (2,2
4,6-trimethylphenyl) cresyl phosphate,
Bis (2,6-dimethylphenyl) xylyl phosphate, bis (2,4,6-trimethylphenyl) xylyl phosphate, bis (2,6-dimethylphenyl) naphthyl phosphate, bis (2,4,6-trimethylphenyl) ) Naphthyl phosphate and the like can be mentioned. Of these, tris (2,6-dimethylphenyl) phosphate, tris (2,4,6-dimethylphenyl) phosphate and bis (2,6-dimethylphenyl) cresylphosphate are particularly preferable.

The aromatic phosphate as the component (b) can be produced by a method known per se. For example, there are a method of reacting an aromatic monohydroxy compound with phosphorus oxychloride, and a method of reacting an aromatic monohydroxy compound with phosphorus trichloride and then oxidizing. In these methods, when a compound corresponding to n = 1 in the general formula (I), for example, diphenyl (2,6-dimethylphenyl) phosphate is by-produced, the amount thereof does not affect the physical properties of the resin composition. If so, it can be used as the component (b) without being particularly separated. When the amount of by-products is about 10% or more, hydrolysis resistance and heat resistance are poor, which is not preferable.

The aromatic phosphate as the component (b) exhibits crystallinity or liquid state, and any of them can be used as the composition of the present invention. Further, the component (b) is suitable as a flame retardant by itself, and has a characteristic that it does not substantially reduce the heat distortion temperature and the physical properties of the component (a). The flame-retardant thermosetting resin composition of the present invention may contain various additives such as other flame retardants, fillers, lubricants, colorants and the like, if necessary. The flame retardant of the component (b) of the present invention can be used for the thermoplastic resin as well as the thermosetting resin of the component (a).

The blending ratio of each component in the flame-retardant thermosetting resin composition of the present invention is appropriately determined according to the type of resin used and the required degree of flame retardancy. Generally, (b) component is 0.1 to 100 parts by weight of (a) component.
It is 100 parts by weight, preferably 5 to 50 parts by weight.

The resin composition of the present invention is prepared by a known method, that is, the thermosetting resin as the component (a) and the aromatic phosphate as the component (b) are mixed by a blender or the like, and mixed by heating with a hot roll or a co-kneader. The flame-retardant molded product is obtained by further molding. Also,
The resin composition of the present invention can be made into a varnish using a solvent, and can be applied and impregnated in a predetermined amount on a substrate to impart flame retardancy to a resin product. Here, examples of the solvent include toluene, alcohol, methyl ethyl ketone, acetone, dimethylformamide, styrene, and the like, and examples of the substrate include paper, glass cloth, glass nonwoven fabric, synthetic fiber, and the like.
This flame-retardant base material can be laminated by heating one sheet or two or more sheets, heating and pressing.

The aromatic phosphate as the component (b) used in the present invention has a low volatility, and it is possible to obtain the electric resistance and mechanical properties without lowering the heat distortion temperature of the flame-retardant thermosetting resin composition. It is possible to remarkably reduce the decrease and to impart an excellent flame retardant effect which cannot be obtained by the conventional organic phosphorus flame retardant alone.

[0020]

The present invention will be described in more detail with reference to the following examples, which are not intended to limit the scope of the present invention. In addition, unless otherwise specified, the number of parts to be added is a value based on weight.

(Synthesis Example 1) A condenser equipped with a stirrer, a dropping funnel, a thermometer and a water scrubber was attached 4
In a one-necked flask, 366 g of 2,6-xylenol (3.
0 mol) and 6.1 g of anhydrous aluminum chloride as a catalyst were charged and mixed by heating. When the temperature of the reaction solution reached 100 ° C., 153 g (1.0 mol) of phosphorus oxychloride was added over about 2 hours. The hydrochloric acid gas generated at this time was led to a water scrubber. After the addition of phosphorus oxychloride was completed, the reaction temperature was gradually raised to 230 ° C. over 4 hours, aged at the same temperature for 2 hours, and then aged under a reduced pressure of 300 torr for 8 hours to complete the reaction. After completion of the reaction, acid washing and hot water washing were performed, and then aromatic phosphate was deposited.
The precipitated crystals were separated by filtration, washed with methanol, and dried under reduced pressure to give a white crystalline powder.

The amount of tris (2,6-dimethylphenyl) phosphate obtained was 308 g (yield 75%). The purity of the crystal by gas chromatography is 9
It was 9.8% or more and had a melting point of 137 to 138 ° C.
This is designated as Compound 1.

(Synthesis Example 2) 2,6-xylenol (3.
Synthesis Example 1 except that 409 g (3.0 mol) of 2,4,6-trimethylphenol was used instead of 0 mol).
Similarly to the above, 353 g (yield 78%) of tris (2,4,6-trimethylphenyl) phosphate was obtained.
Purity of crystals by gas chromatography is 99.8%
It was above, and the melting point was 108 to 109 ° C. This is designated as Compound 2.

(Synthesis Example 3) A condenser equipped with a stirrer, a dropping funnel, a thermometer and a water scrubber was attached 4
In a two-necked flask, 244 g of 2,6-xylenol (2.
0 mol) and 1.5 g of anhydrous magnesium chloride as a catalyst were charged and mixed with heating. When the temperature of the reaction solution reached 120 ° C., 153 g (1.0 mol) of phosphorus oxychloride was added over about 2 hours. The hydrochloric acid gas generated at this time was led to a water scrubber. After the addition of phosphorus oxychloride was completed, the reaction temperature was gradually raised to 180 ° C. over 2 hours to complete the reaction. After cooling, 108 g of p-cresol (1.
0 mol) and 1.5 g of anhydrous magnesium chloride were charged and mixed with heating. The temperature of the reaction solution was gradually raised to 180 ° C. over 2 hours to carry out a dehydrochlorination reaction. Next, after aging at the same temperature for 2 hours, aging was further performed for 2 hours under reduced pressure of 200 torr to complete the reaction. After completion of the reaction, acid washing and hot water washing were performed, and then distillation was performed to obtain a white solid.

The amount of the obtained bis (2,6-dimethylphenyl) p-cresyl phosphate was 376 g (yield 95%). The purity of the solid by gas chromatography was 98.5% or higher, and the melting point was 70 to 71 ° C. This is designated as Compound 3.

(Synthesis Example 4) Yellow liquid bis (2,6--) was prepared in the same manner as in Synthesis Example 3 except that 122 g (1.0 mol) of xylenol was used instead of cresol (1.0 mol). The yield of dimethylphenyl) xylyl phosphate was 390 g (yield 95%). The purity of the liquid measured by gas chromatography was 98.0% or higher. This is designated as Compound 4.

(Examples 1 to 4) With respect to the compounds 1 to 4 synthesized in Synthesis Examples 1 to 4, 250 g of each compound was subjected to a pressure cooker test at 120 ° C./100% RH for 96 hours under a saturated vapor pressure of 2 atm. Then, the acid value was measured and the hydrolysis resistance was evaluated. Table 1 shows the results.

Comparative Examples 1 to 3 The following compounds 5 to 7 were used in place of the compounds synthesized in Synthesis Examples 1 to 4 and evaluated in the same manner as in Example 1. Compound 5: triphenyl phosphate (manufactured by Daihachi Chemical Industry Co., Ltd .; trade name TPP) Compound 6: tricresyl phosphate (manufactured by Daihachi Chemical Industry Co., Ltd .; trade name TCP) Compound 7: trixylyl phosphate (manufactured by Daihachi Chemical Industry Co., Ltd.) Trade name TXP) The results are shown in Table 1.

[0029]

[Table 1]

From Table 1, it can be seen that the aromatic phosphate of the present invention has excellent hydrolysis resistance.

(Examples 5 to 8) Component (a): 100 parts of a commercially available phenol resin varnish having a solid content of 60%, component (b): Compounds 1 to 4 synthesized above
15 parts of any one of the above was added and mixed. Next, this was impregnated in linter paper and dried to obtain resin-impregnated paper having a resin content of 45%. Furthermore, 9 sheets of this are laminated to each other at 150 ° C. and 90
Pressure was applied for 50 minutes under the condition of g / cm ² to obtain a laminated plate having a thickness of 2 mm. The same operation was repeated to obtain four laminated plates.

The obtained laminated plate was evaluated based on each test method. The flame retardancy was determined according to the UL-94 standard, and classified into four types of V-0, V-1, V-2 and HB. The solder heat resistance was measured in accordance with JIS C-6481 at a temperature of 260 ° C., and the time (seconds) until swelling and peeling occurred was measured. Furthermore, the punching workability is ASTM
According to the standard D-617, with a load of 18.6 kg / cm ² ,
The insulating property was measured according to JIS standard C-6481, and the tracking resistance was measured according to the electrolytic droplet dropping method. The results are shown in Table 2.

(Comparative Examples 4 to 6) Component (b): Instead of the compounds synthesized in Synthetic Examples 1 to 4,
A laminated board was obtained in the same manner as in Example 5 except that the compounds 5 to 7 were blended. The obtained laminated board was evaluated in the same manner as in Example 5. The results are shown in Table 2.

[0034]

[Table 2]

From Table 2, the flame-retardant thermosetting resin composition containing the aromatic phosphate of the present invention is more difficult than the thermosetting resin composition containing the conventional flame retardant. It is recognized that in addition to being excellent in flame resistance and low-temperature punching workability, it is also excellent in bleeding resistance of the flame retardant from the laminate, and particularly excellent in tracking resistance and insulation due to good hydrolysis resistance.

(Examples 9 to 12) Component (a): 100 parts of a commercially available epoxy resin varnish having a solid content of 50% and 3 parts of dicyanamide, and component (b): compounds 1 to 4 synthesized in Synthesis Examples 1 to 4. 15 parts of any one of the above was added and mixed. Thereafter, four laminated plates were obtained in the same manner as in Example 5. The obtained laminated board was evaluated in the same manner as in Example 5. Table 3 shows the results.

(Comparative Examples 7 to 9) Component (b): Instead of the compounds synthesized in Synthetic Examples 1 to 4,
A laminated board was obtained in the same manner as in Example 5 except that the compounds 5 to 7 were blended. The obtained laminated board was evaluated in the same manner as in Example 5. Table 3 shows the results.

[0038]

[Table 3]

From Table 3, the flame-retardant thermosetting resin composition containing the aromatic phosphate of the present invention has a lower temperature than the thermosetting resin composition containing the conventional flame retardant. It is recognized that in addition to being excellent in punching workability, it is also excellent in bleeding resistance of the flame retardant from the laminate, particularly in tracking resistance, heat resistance and insulation.

[0040]

The flame-retardant thermosetting resin composition containing the flame-retardant aromatic phosphate according to the present invention has the following properties as compared with the thermosetting resin composition containing the conventional flame retardant: In addition to being excellent in low-temperature punching workability, it is also excellent in bleeding resistance of the flame retardant from the laminate, and in particular, remarkable improvement effects are recognized in tracking resistance, heat resistance and insulation.

Claims (3)

[Claims] 1. A thermosetting resin (a), and (b) a general formula (I): (In the formula, R ¹ and R ² are the same or different and each is a lower alkyl group, R ³ is a hydrogen atom or a low alkyl group, and R ⁴ has 6 carbon atoms.
To 20 aromatic hydrocarbon residues, n is an integer of 2 or 3), and a flame-retardant thermosetting resin composition comprising the aromatic phosphate. 2. The amount of (b) relative to 100 parts by weight of (a) component.
The component is blended in a ratio of 0.1 to 100 parts by weight.
The composition as described. 3. The composition according to claim 1, wherein R ¹ and R ^{2 in} the general formula (I) are the same lower alkyl group.